A New Mechanism of NK Cell Cytotoxicity Activation: The CD40–CD40 Ligand Interaction

NK recognition is regulated by a delicate balance between positive signals initiating their effector functions, and inhibitory signals preventing them from proceeding to cytolysis. Knowledge of the molecules responsible for positive signaling in NK cells is currently limited. We demonstrate that IL-2–activated human NK cells can express CD40 ligand (CD40L) and that recognition of CD40 on target cells can provide an activation pathway for such human NK cells. CD40-transfected P815 cells were killed by NK cell lines expressing CD40L, clones and PBLderived NK cells cultured for 18 h in the presence of IL-2, but not by CD40L-negative fresh NK cells. Cross-linking of CD40L on IL-2–activated NK cells induced redirected cytolysis of CD40-negative but Fc receptor-expressing P815 cells. The sensitivity of human TAP-deficient T2 cells could be blocked by anti-CD40 antibodies as well as by reconstitution of TAP/MHC class I expression, indicating that the CD40-dependent pathway for NK activation can be downregulated, at least in part, by MHC class I molecules on the target cells. NK cell recognition of CD40 may be important in immunoregulation as well as in immune responses against B cell malignancies.NK cells represent a distinct lineage of lymphocytes that are able to kill a variety of tumor (1), virus-infected (2), bone marrow transplanted (3), and allogeneic target cells (4). NK cells do not express T cell receptors or immunoglobulins and are apparently normal in mice with defects in the recombinase machinery (5, 6).Our knowledge about NK cell specificity has increased considerably in the last years. NK cells can probably interact with target cells by a variety of different cell surface molecules, some involved in cell adhesion, some activating the NK cytolytic program (7, 8), and other ones able to inhibit this activation by negative signaling (as reviewed in reference 9).A common feature of several inhibitory NK receptors is the capability to bind MHC class I molecules (10, 11), as predicted by the effector inhibition model within the missing self hypothesis of recognition by NK cells (12–14). Interestingly, the MHC class I receptors identified so far belong to different gene families in mouse and man; these are the p58/p70/NKAT or killer cell inhibitory receptors (KIR)¹ of the immunoglobulin superfamily in man and the Ly49 receptors of the C-type lectin family in the mouse. There is also evidence that MHC class I molecules can be recognized as triggering signals in NK cells of humans, rats as well as mice (13). The inhibitory receptors allow NK cells to kill tumor or normal cell targets with deficient MHC class I expression (12, 14). This does not exclude that other activating pathways can override inhibition by MHC class I molecules (15) and, even in their absence, there must be some activating target molecules that initiate the cytolytic program. Several surface molecules are able to mediate positive signals in NK cells. Some of these structures, like NKRP1 (16), CD69 (17), and NKG2 (18) map to the NK complex region (NKC) of chromosome 6 in mice and of chromosome 12 in humans (13). CD2 (19) and CD16 (20) molecules can also play a role in the activation pathway.NK cells resemble T cells in many respects, both may arise from an immediate common progenitor (21, 22), and share the expression of several surface molecules (23). NK cells produce cytokines resembling those secreted by some helper T cell subsets (24) and contain CD3 components in the cytoplasm (21). The expression of some surface structures, involved in TCR-dependent T cell costimulation, like CD28 in human (25), has been described on NK cells, but the functional relevance of these molecules for NK activation processes has not been fully established.Another T cell molecule of interest is CD40L, which interacts with CD40, a 50-kD membrane glycoprotein expressed on B cells (26), dendritic cells (27), and monocytes (28). CD40 is a member of the tumor necrosis factor/nerve growth factor receptor family (29) which includes CD27 (30), CD30 (31), and FAS antigen (32). Murine and human forms of CD40L had been cloned and found to be membrane glycoproteins with a molecular mass of ∼39 kD induced on T cells after activation (33). Also mast cells (34), eosinophils (35), and B cells (36) can be induced to express a functional CD40L. The CD40L–CD40 interaction has been demonstrated to be necessary for T cell–dependent B cell activation (33, 37). Mutations in the CD40L molecule cause a hyper-IgM immunodeficiency condition in man (38, 39, 40). On the other hand, CD40–CD40L interactions also orchestrate the response of regulatory T cells during both their development (41, 42) and their encounter with antigen (43, 44).NK cells have also been suggested to play a role in B cell differentiation and immunoglobulin production (45). Therefore, it was of interest to investigate whether NK cells could use a CD40-dependent pathway in their interactions with other cells. Therefore, we have investigated the ability of target cells expressing CD40 to induce activation of NK cytotoxicity.     

TRAF-interacting Protein (TRIP): A Novel Component of the Tumor Necrosis Factor Receptor (TNFR)- and CD30-TRAF Signaling Complexes That Inhibits TRAF2-mediated NF-κB Activation

Through their interaction with the TNF receptor–associated factor (TRAF) family, members of the tumor necrosis factor receptor (TNFR) superfamily elicit a wide range of biological effects including differentiation, proliferation, activation, or cell death. We have identified and characterized a novel component of the receptor–TRAF signaling complex, designated TRIP (TRAF-interacting protein), which contains a RING finger motif and an extended coiled-coil domain. TRIP associates with the TNFR2 or CD30 signaling complex through its interaction with TRAF proteins. When associated, TRIP inhibits the TRAF2-mediated NF-κB activation that is required for cell activation and also for protection against apoptosis. Thus, TRIP acts as a receptor–proximal regulator that may influence signals responsible for cell activation/proliferation and cell death induced by members of the TNFR superfamily.Members of the TNF receptor (TNFR)¹ superfamily play important roles in the induction of diverse signals leading to cell growth, activation, and apoptosis (1). Whether the signals induced by a given receptor leads to cell activation or death is, however, highly cell-type specific and tightly regulated during differentiation of cells. For example, the TNFRs can exert costimulatory signals for proliferation of naive lymphocytes but also induce death signals required for deletion of activated T lymphocytes (1). The cytoplasmic domains of these receptors lack intrinsic catalytic activity and also exhibit no significant homology to each other or to other known proteins. Exceptions to this include Fas(CD95) and TNFR1 that share a significant homology within an 80–amino acid region of their cytoplasmic tails (called the “death domain”; 2, 3). Therefore, it is suggested that the TNFR family members can initiate different signal transduction pathways by recruiting different types of intracellular signal transducers to the receptor complex (1).Indeed, several types of intracellular signal transducers have been identified that initiate distinct signal transduction pathways when recruited to the members of TNFR superfamily (4–19). Recent biochemical and molecular studies showed that a class of signal-transducing molecules are recruited to Fas(CD95) or TNFR1 via interaction of the death domains (2, 3, 6, 12, 17, 20). For example, Fas(CD95) and TNFR1 recruit FADD(MORT1)/RIP or TRADD/FADD (MORT1)/RIP through the interactions of their respective death domains (2, 3, 6, 12, 17, 20, 21). Clustering of these signal transducers leads to the recruitment of FLICE/ MACH, and subsequently, to cell death (13, 14).The TNFR family members can also recruit a second class of signal transducers called TRAFs (TNFR-associated factor), some of which are responsible for the activation of NF-κB or JNK (9, 20, 22). TRAF proteins were identified by their biochemical ability to interact with TNFR2, CD40, CD30, or LT-βR (4, 5, 10, 11, 15, 23–27). These receptors interact directly with TRAFs via a short stretch of amino acids within their cytoplasmic tails, but do not interact with the death domain containing proteins (4, 5, 15, 24–27). To date, five members of the TRAF family have been identified as signaling components of the TNFR family members. All TRAF members contain a conserved TRAF domain, ∼230 amino acids in length, that is used for either homo- or heterooligomerization among the TRAF family, for interactions with the cytoplasmic regions of the TNFR superfamily, or for interactions with downstream signal transducers (4, 5, 8, 10, 11, 19, 23–25, 28). In addition to the TRAF domain, most of the TRAF family members contain an NH₂-terminal RING finger and several zinc finger structures, which appear to be important for their effector functions (4, 5, 10, 11, 23–25).Several effector functions of TRAFs were revealed by recent experiments based on a transfection system. TRAF2, first identified by its interaction with TNFR2 (4), was subsequently shown to mediate NF-κB activation induced by two TNF receptors, CD40 and CD30 (9, 28–30). TRAF5 was also implicated in NF-κB activation mediated by LTβR (10), whereas TRAF3 (also known as CRAF1, CD40bp, or LAP1; references 5, 11, 24, and 25) was shown to be involved in the regulation of CD40-mediated CD23 upregulation in B cells (5). The role of other TRAF members in the TNFR family–mediated signal transduction is not clear. They may possess some effector functions as yet to be revealed, or work as adapter proteins to recruit different downstream signal transducers to the receptor complex. For example, TRAF1 is required for the recruitment of members of the cellular inhibitor of apoptosis protein (c-IAP) family to the TNFR2-signaling complex (7). In addition to the signal transduction by the TNFR family members, TRAFs may regulate other receptor-mediated signaling pathways. For example, TRAF6 is a component of IL-1 receptor (IL1R)–signaling complex, in which it mediates the activation of NF-κB by IL-1R (31). Since TRAFs form homo- or heterooligomers, it is suggested that the repertoire of TRAF members in a given cell type may differentially affect the intracellular signals triggered by these receptors. This may be accomplished by the selective interaction of TRAFs with a specific set of downstream signal transducers. Although many aspects of TRAF-mediated effector functions leading to cellular activation have been defined, it needs to be determined whether TRAF proteins will also mediate the apoptotic signals induced by the “death-domain-less” members of the TNFR superfamily (1, 27, 32–36).Here we report the isolation and characterization of a novel component of the TNFR superfamily/TRAFs signaling complex, named TRIP (TRAF-interacting protein). TRIP associates with the receptor/TRAF signaling complex, and inhibits the TRAF2-mediated NF-κB activation. Biochemical studies indicate that TRIP associates with the TNFR2 or CD30 receptor complex via its interaction with TRAF proteins, suggesting a model which can explain why the ligation of these receptors can promote different cell fates: proliferation or death.     

Needle EMG Response of Lumbar Multifidus to Manipulation in the Presence of Clinical Instability

A proposed mechanism for the persistence of low back pain due to clinical instability is a decrease in control of local spinal musculature, more specifically decreased recruitment of multifidus. Altered segmental mechanoreceptor input has been proposed as a contributing factor responsible for a decrease in local muscle recruitment. In this case report, immediate changes in the recruitment of the deep multifidus following manipulation were examined using needle EMG and isometric testing of trunk rotational force. Trunk rotational force appeared to improve while the multifidus demonstrated a decrease in activity as measured by needle EMG. No specific conclusions can be drawn from this report; however, the results do suggest that immediate multifidus function may be influenced with manipulation, resulting in improved muscular control of the trunk.KEYWORDS: Instability, Manipulation, Multifidus, Needle EMGNumerous definitions of clinical instability exist; as defined by Bogduk, instability occurs when at any time during movement, there is a change in the ratio of translation to rotation at a segment¹. Panjabi described instability as the inability of the spine to maintain its pattern of displacement under physiologic loads². Actual determination of the presence of clinical instability remains controversial^3,4. Subjective reports from patients with clinical instability may include reports of long-term intermittent pain, increased pain with transitional movements, feelings of giving way or locking, pain with sustained positions, and a condition that is progressively worsening^5–9. Signs of clinical instability include mild to moderate loss of trunk motion, Gower''s sign, lateral shift, absence of neurological signs, and hypermobility with segmental stress testing^6,7,9–11.It has been proposed that this clinical problem may prove difficult to rehabilitate because of a decrease in the recruitment and cross-sectional area of the multifidus¹² and an alteration in normal segmental articular mechanoreceptor input^10,13–18. Several studies have suggested that activity of the trunk muscles is altered in the presence of lower back pain^{15,17,19–22}.Recruitment of the multifidus has been reported as an essential component during rehabilitation of patients with lower back pain^20–22. However, it has also been proposed that restoration of normal articular motion precedes attempts at strengthening^7,23, that segmental control is necessary for spinal stability^{7,8,21,22,24–26}, and that multifidus activity is not directly related to direction of forces placed on the spinal column^{20,21,27–29}. Other reports have suggested that reflexive muscular activity of the multifidus is diminished with laxity in the viscoelastic structures of the feline spine¹⁹, with prolonged positioning or loading^19,30, and that multifidus recovery is not automatic following an episode of low back pain³¹.Recent reports have suggested that multifidus function may be affected with spinal manipulation¹³ and that mechanical forces may alter EMG activity of the multifidus¹⁶. Additional studies have documented changes in strength^32–34, muscular activity^35–37, neuromuscular reflex³⁸, and pain sensitivity³⁹ following manipulation. It has not been reported that treatment focused at restoring normal articular motion or stimulating local mechanoreceptors will affect multifidus function when measured using needle EMG.This case report attempts to identify the immediate changes in multifidus activity measured with needle EMG following manipulation of the lumbar spine that is targeted at a level identified as having decreased muscle bulk of the multifidus, abnormal findings in the biomechanical examination, and a decrease in trunk rotational control and strength. Findings may provide clinicians/researchers with ideas for further investigation into treatment of clinical instability.     

Mouse Ly-49A Interrupts Early Signaling Events in Natural Killer Cell Cytotoxicity and Functionally Associates with the SHP-1 Tyrosine Phosphatase

The lytic activity of natural killer (NK) cells is inhibited by the expression of class I major histocompatibility complex (MHC) antigens on target cells. In murine NK cells, Ly-49A mediates inhibition of cytotoxicity in response to the class I MHC antigen H-2D^d. In this report, we studied the function of mouse Ly-49A in both the rat NK cell tumor line, RNK-16, transfected with Ly-49A cDNA, and in primary NK cells. We show that ligation of Ly-49A by H-2D^d inhibits early signaling events during target cell stimulation, including polyphosphoinositide turnover and tyrosine phosphorylation. We also show that Ly-49A directly associates with the cytoplasmic tyrosine phosphatase SHP-1, and that Ly-49A function is impaired in NK cells from SHP-1 mutant viable motheaten mice and from SHP-1–deficient motheaten mice. Finally, we demonstrate that mutational substitution of the tyrosine within the proposed SHP-1 binding motif in Ly-49A completely abrogates inhibition of NK cell cytotoxicity through this receptor. These results demonstrate that Ly-49A interrupts early activating signals in NK cells, and that SHP-1 is an important mediator of Ly-49A function.NK cells and some T cells express a variety of type II transmembrane receptors characterized by extracellular C-type lectin domains (1). In mice, these proteins include the members of the Ly-49 family (2–8), which recognize MHC class I molecules on target cells (6–10), and the NKR-P1 family, whose physiologic ligands have yet to be determined (11–13). While the NKR-P1 molecules activate NK cell cytotoxicity (14–16), at least three members of the Ly-49 family inhibit NK cell function (6–8).Susceptible targets stimulate phosphoinositide turnover, calcium mobilization, and the induction of protein tyrosine phosphorylation in NK cells. These signals have been associated with activation of NK cell cytotoxic responses (17–20). The NKR-P1 lectin-like receptor also transduces these activating signals in NK cells (14–16). In contrast, mouse Ly49A inhibits NK cell cytotoxicity upon ligation by the target cell MHC class I molecules H-2D^d or H-2D^k (6, 9, 10). The mechanisms by which Ly-49A interrupts NK cell activation are poorly understood, but important clues can be derived from structural motifs within the Ly-49A molecule.The Ly-49A cytoplasmic domain contains the amino acid sequence VxYxxV, which constitutes a proposed binding motif for the cytoplasmic tyrosine phosphatase, SHP-1 (21, 22). SHP-1 is an SH2 domain containing tyrosine phosphatase, expressed in hematopoietic cells that can inhibit specific cellular functions. SHP-1 negatively modulates signaling through the erythropoietin receptor (23, 24), and it inhibits activation of B cells through its association with FcγRIIB1 (25–28). In human NK cells, SHP-1 has been implicated in inhibition of cytotoxicity through its association with the killer inhibitory receptors (KIRs)¹, members of the Ig family that bind to human MHC class I molecules (21, 29, 30). The presence of a proposed SHP-1 binding motif in the cytoplasmic domain of Ly-49A suggests that this murine receptor may also functionally associate with SHP-1. A tyrosine-phosphorylated synthetic tridecapeptide derived from the cytoplasmic domain of Ly-49A has recently been shown to bind to SHP-1 and to the related phosphatase SHP-2, but the functional relevance of these findings to intact Ly-49A has not yet been examined (22). In this report, we demonstrate that ligation of Ly-49A interrupts early signals for NK cell activation, inhibiting tyrosine phosphorylation and polyphosphoinositide turnover. We also demonstrate that intact Ly-49A directly associates with SHP-1. Moreover, we show that the full inhibitory effect of Ly-49A in NK cells requires intact SHP-1 function as well as the tyrosine residue within the proposed SHP-1 binding site of Ly-49A.     

Multimodal Management of Mechanical Neck Pain Using a Treatment Based Classification System

The purpose of this case study was twofold: 1) to illustrate the use of a treatment-based classification (TBC) system to direct the early intervention of a patient with mechanical neck pain, and 2) to show the progression of this patient with multimodal-modal intervention. The patient exhibited axial neck pain with referral into her upper extremity. Her pain peripheralized with cervical range of motion and centralized with joint mobilization placing her primarily in the centralization category. Her poor posture and associated muscle weakness along with the chronicity of symptoms placed her secondarily into the exercise and conditioning group resulting in a multi-modal treatment as the patient progressed. Although the design of this case report prevents wide applicability, this study does illustrate the effective use of the TBC system for the cervical spine as captured by accepted outcomes measures.KEYWORDS: Multi-Modal Intervention, Neck Pain, Treatment-Based ClassificationMechanical neck pain commonly arises insidiously¹ and is generally multifactorial in origin, including one or more of the following: poor posture, anxiety, depression, neck strain, and sporting or occupational activities^2,3. In an estimated 50–80% of cases involving back or neck pain, an underlying pathology cannot be definitively determined⁴. Regardless of the primary source of pain, the prognosis for individuals experiencing chronic neck pain is poor, as many patients continue to suffer from persistent pain and disability following conservative physical therapy intervention^5,6. Chronic neck pain appears to be more persistent than low back pain⁷, and it is second only to lumbar pain as the causal factor for time missed from work.Despite the prevalence, less-than optimal prognosis, associated risk of disability, and economic consequences of individuals suffering from mechanical neck pain, there remains a significant gap in the literature, which fails to provide sufficient, high-quality evidence to effectively guide the conservative treatment of this patient population⁸. This lack of quality evidence largely stems from the poorly understood clinical course of neck pain in conjunction with the inconclusive results related to the efficacy of commonly used interventions^2,9,10. Left with poorer quality trials as a guide, Physical Therapists approach the management of this pathology with a plethora of interventions such as manual therapy (MT), therapeutic exercises, manual/mechanical traction, modalities, massage, and functional training^5,10–12.One reason the outcomes in the PT literature may be less than impressive is that many of the studies looking at conservative treatments for the management of neck pain use a heterogeneous subject population¹³. Many studies also combine some or all of the following clinical manifestations into the same case mix during clinical trials: acute whiplash, subacute and chronic mechanical disorders, and chronic cervical headache. The identification of a homogeneous patient population would likely enhance the potential to initiate targeted interventions and to specifically assess treatment responses¹⁴. One solution to acquiring more homogeneous patient populations is the use of treatment-based classification (TBC) systems.Classification systems are developed with the intent of both directing treatment and improving clinical outcomes by identifying detailed combinations of treatments that specifically benefit a subgroup of patients presenting with certain characteristics^5,15. The principle supporting classification systems centers around the following notion: a decrease in uncertainty concerning appropriate, effective treatments could be observed via the linkage of an impairment diagnosis to a treatment choice¹⁶. Classification systems can also serve to improve clinical research by identifying evidence-based practice patterns for specified subgroups of patients⁵. The goal of this model is to heighten decision-making abilities of clinicians in relation to intervention strategy and prognosis¹⁶.While the classification-based strategy has been shown to yield optimal outcomes for the lumbar spine^17–20, comparatively nominal research has been performed to investigate patient outcomes using a similar classification-based approach for the cervical spine^5,16. Despite this preliminary work, research has not served to confirm the validity of such a system⁵. One recent study reported a 98% between-raters percentage agreement with the use of a proposed treatment-based classification (TBC) system (Figure ​(Figure11)⁵. This indicates that the algorithm could be applied consistently by different examiners who are considering the same patient data. With intent to assist in the validation of the outcomes using the aforementioned strategy, the purpose of this case study is to describe the use of a TBC system approach in the management of a single patient with mechanical neck pain and referred pain into the arm.Open in a separate windowFIGURE 1Proposed classification decision-making algorithm.⁵ MVA= motor vehicle accident, NDI = Neck Disability Index. Used with permission.     

Comparison of Manual Therapy Techniques with Therapeutic Exercise in the Treatment of Shoulder Impingement: A Randomized Controlled Pilot Clinical Trial

The purpose of this double-blind, randomized controlled pilot study was to compare the effectiveness of four physical therapy interventions in the treatment of primary shoulder impingement syndrome: 1) supervised exercise only, 2) supervised exercise with glenohumeral mobilizations, 3) supervised exercise with a mobilization-with-movement (MWM) technique, or 4) a control group receiving only physician advice. Thirty-three subjects diagnosed with primary shoulder impingement were randomly assigned to one of these four groups. Main outcome measures included 24-hour pain (VAS), pain with the Neer and Hawkins-Kennedy tests, shoulder active range of motion (AROM), and shoulder function (SPADI). Repeated-measures analyses indicated significant decreases in pain, improved function, and increases in AROM. Univariate analyses on the percentage of change from pre- to post-treatment for each dependent variable found no statistically significant differences (P<0.05) between the four groups. Although not significant, the MWM and mobilization groups had a higher percentage of change from pre- to post-treatment on all three pain measures (VAS, Neer, Hawkins-Kennedy). The three intervention groups had a higher percentage of change on the SPADI. The MWM group had the highest percentage of change in AROM, and the mobilization group had the lowest. This pilot study suggests that performing glenohumeral mobilizations and MWM in combination with a supervised exercise program may result in a greater decrease in pain and improved function although studies with larger samples and discriminant sampling methods are needed.KEYWORDS: Exercise, Glenohumeral Mobilization, Mobilization with Movement, Shoulder Impingement SyndromeShoulder impingement syndrome, the most common diagnosis of shoulder dysfunction¹, is often described as shoulder pain exacerbated by overhead activities^2,3. Primary shoulder impingement occurs when the rotator cuff tendons, long head of the biceps tendon, glenohumeral joint capsule, and/or subacromial bursa become impinged between the humeral head and anterior acromion⁴. Primary impingement may be due to intrinsic factors: rotator cuff weakness^5,6, chronic inflammation of the rotator cuff tendons and/or subacromial bursa^7–9, rotator cuff degenerative tendinopathy^7,10, and posterior capsular tightness leading to abnormal anterior/superior translation of the humeral head^11,12. It may also be due to extrinsic factors: possession of a curved or hooked acromion^13–15, acromial spurs¹⁶, or postural dysfunction^17,18. Secondary shoulder impingement is defined as a relative decrease in the subacromial space due to glenohumeral joint instability or abnormal scapulothoracic kinematics^6,19–22. Commonly seen in athletes engaging in overhead throwing activities^23,24, secondary impingement occurs when the rotator cuff becomes impinged on the posterior-superior edge of the glenoid rim when the arm is placed in end-range abduction and external rotation⁷. This positioning becomes pathologic during excessive external rotation, anterior capsular instability, scapular muscle imbalances^21,25, and/or upon repetitive overload of the rotator cuff musculature^23,26.Physical therapy has been found to be effective in reducing pain and disability in patients with shoulder impingement. Effective interventions include therapeutic exercises focusing on strengthening the rotator cuff and scapular stabilizing musculature^27–34, stretching to decrease capsular tightness³⁵, scapular taping techniques³⁶, and patient education of proper posture³⁷. Studies suggest the incorporation of joint mobilizations to treat shoulder impingement results in superior outcomes compared with therapeutic exercise alone^28,29,38. Some researchers propose that a mobilization force can be selectively directed to a specific area of the capsule to restore capsular extensibility^29,39. Studies have found that individuals with shoulder impingement often have a tight posterior capsule resulting in altered glenohumeral arthrokinematics^11,40 and a decrease in glenohumeral internal rotation range of motion (ROM)^6,12,40. Thus, performing grade III or IV mobilizations aimed at restoring posterior capsule mobility in subjects with shoulder impingement may result in increased active ROM and decreased impingement symptoms, whereas all grades of mobilizations (I-IV) may result in pain reduction³².A manual therapy approach to treating shoulder dysfunction is the Mulligan concept of mobilization with movement (MWM)^41,42. The goal of performing MWM is immediate and sustained improvement in joint pain and mobility. Mulligan''s techniques entail having the physical therapist apply an accessory mobilization to a peripheral joint while the patient simultaneously generates active movement. During the technique, the therapist must continually monitor the patient to ensure that no pain is recreated. If pain commences, the therapist must investigate different treatment planes and/or grades of accessory motion to ensure pain-free movement. Mulligan believes that failure to improve pain-free ROM indicates that the therapist has not found the correct treatment plane or grade of mobilization, or simply that the technique is not indicated. Mulligan''s theory is that joint injury or dysfunction results in a positional fault or chronic state of mal-alignment within the joint, and the techniques may assist in properly aligning the joint or restoring the joint''s tracking mechanism^41,42. Only two studies have been published supporting the benefits of performing a shoulder MWM technique in treating shoulder dysfunction^43,44. One case study using MWM to treat a patient with shoulder impingement reported a decrease in pain, improvement in function, and improvement in shoulder abduction AROM⁴³.Although therapeutic exercise has been shown to be effective in treating shoulder impingement symptoms^27–34, very few studies have evaluated the effectiveness of incorporating glenohumeral joint mobilizations^28,29,39,45, and no randomized controlled trials have used a MWM technique to treat shoulder impingement. The purpose of this double-blind, randomized controlled pilot study was to compare the effectiveness of four physical therapy interventions in the treatment of primary shoulder impingement syndrome: supervised exercise only, supervised exercise with glenohumeral mobilizations, supervised exercise with a MWM technique, or a control group receiving only physician advice. A secondary purpose was to examine the appropriateness of the sampling and data collection procedures for a future study with more power.     

Homocysteine-mediated thrombosis and angiostasis in vascular pathobiology

The mechanisms by which homocysteine contributes to atherothrombosis are complex and their in vivo relevance uncertain. In this issue of the JCI, Jacovina and colleagues report a unique in vivo mechanism by which homocysteine may contribute to vascular disease (see the related article beginning on page 3384). This group had previously reported that homocysteine impairs endothelial cell surface plasminogen activation by posttranslationally modifying annexin A2, the coreceptor for plasminogen and tissue plasminogen activator. They now show that an annexin A2–deficient mouse rendered hyperhomocysteinemic by dietary means has impaired fibrinolysis, perivascular fibrin persistence, and attenuated angiogenesis (angiostasis). Potential mechanisms by which homocysteine-dependent changes in endothelial phenotype link thrombosis to angiostasis are reviewed and their relationship to homocysteine-dependent vascular disease considered. Over the past 30 years, evidence from many in vitro and in vivo studies supports an association between mild to moderate hyperhomocysteinemia and vascular dysfunction and disease (1). A key mechanism that predisposes to vascular disease in hyperhomocysteinemia is endothelial dysfunction (2). Homocysteine induces endothelial dysfunction in part by promoting oxidant stress, as illustrated in cellular studies (3, 4) and in genetic animal models (2, 5, 6). The mechanisms for homocysteine-induced oxidant stress are complex and include inhibiting the translation of glutathione peroxidase-1 (7), a major antioxidant enzyme in vascular cells that regulates mitochondrial reactive oxygen species flux (8) and whose overexpression rescues the normal vascular phenotype of hyperhomocysteinemic mice (9); upregulation of NADPH oxidase expression (10); enhanced expression of inducible nitric oxide synthase (10) and uncoupling of nitric oxide synthases (11); and decreased glutathione levels owing to decreased cysteine synthesis (12), thereby shifting the redox balance of endothelial cells toward oxidant stress. Among the specific phenotypic properties of the endothelial cell that go awry in hyperhomocysteinemia are its antithrombotic properties. Hyperhomocysteinemia produces a prothrombotic state (13), some mechanisms for which include enhanced platelet activation, enhanced coagulation (likely as a consequence of increased tissue factor expression; ref. 14), and attenuated fibrinolysis. Two recognized mechanisms for reduced fibrinolysis include posttranslational modification of fibrinogen by homocysteinylation, rendering the fibrin derived from fibrinogen relatively resistant to plasmin (15), and increased activity of thrombin-activatable fibrinolysis inhibitor (TAFI) (16). In this issue of the JCI, Jacovina and colleagues (17) report the existence of another antifibrinolytic mechanism caused by homocysteine. In the group’s earlier work (18, 19), they demonstrated that the calcium-regulated, phospholipid-binding protein annexin A2 is an endothelial coreceptor for TPA and plasminogen that facilitates plasminogen activation by enhancing the catalytic efficiency of TPA. They next demonstrated that homocysteine forms a mixed disulfide bond with the Cys9 residue of annexin A2, which decreases the binding affinity of the receptor for TPA. As a result of this posttranslational modification, endothelial cell surface plasminogen activation is markedly attenuated (18). These observations were next confirmed in vivo using Anxa2^–/– mice, which showed increased perivascular fibrin deposition and impaired fibrin clearance. Fibrin formation and plasmin-dependent remodeling are not only important in the hemostatic response to vascular injury, but also for luminal recanalization and angiogenesis during the healing phase. Consistent with this role for fibrin and plasmin, the Anxa2^–/– mice showed significantly impaired angiogenesis in a range of vascular injury models (neoangiogenesis) (19). In their latest study, reported in this issue of the JCI (17), the investigators found that moderate hyperhomocysteinemia induced by feeding mice methionine also leads to impaired fibrinolysis with perivascular fibrin persistence as well as attenuated angiogenesis (angiostasis). In this animal model, they observed significantly reduced TPA–annexin A2 binding and plasminogen activation consistent with the importance of endothelial cell surface plasmin activity for normal fibrin clearance and angiogenesis. The pathophenotype was readily reversed by infusion of wild-type recombinant annexin A2 into the hyperhomocysteinemic mice (17).     

Manual Correction of an Acute Lumbar Lateral Shift: Maintenance of Correction and Rehabilitation: A Case Report with Video

The acute onset lumbar lateral shift, otherwise known as a list or acute scoliosis, is a common clinical observation associated with low back pain. In general orthopaedics, the presence of a lateral shift is associated with a poor prognosis; however, a manual correction method devised by McKenzie is claimed to produce rapid reversal of the deformity and reduction in pain. This single-case report presents the details of the McKenzie Mechanical Diagnosis and Treatment (MDT) management of a major right-sided lateral shift, which includes the manual correction technique, self-correction and management, prophylaxis, pain ablation, and rehabilitation to a high level of athletic function, with long-term follow-up at 9 months. The lateral shift is widely accepted as being associated with disc pathology, but the exact mechanism of shift production remains speculative. hypotheses include muscle spasm, avoidance of irritation of a spinal nerve, and space-occupying or space-deficient disc mechanics. The hypotheses used to explain the lateral shift phenomena are discussed. (Case report is supplemented by video stream, available at jmmtonline.com/).KEYWORDS: Lateral Shift, McKenzie, Mechanical Diagnosis and Treatment (MDT), ScoliosisThe presentation of a lateral shift or trunk list associated with development of acute low back pain is a common clinical event¹. In the opinion of Porter and Miller, it is undoubtedly associated with a disc protrusion and associated with a poor prognosis for conservative management². This acute onset deformity is variously called a sciatic scoliosis or lateral shift³, trunk list², acute lumbar/sciatic scoliosis⁴, wind-swept spine⁵, or lateral deviation⁶.Prevalence of the acute lateral shift associated with back pain varies according to the clinical setting and circumstances. About a quarter of patients presenting on referral with low back pain to a physiotherapy clinic in New Zealand had a lateral shift³. Of 88 (12.5%) consecutive acute and chronic patients referred to physical therapy in the US, 11 were classified as having a relevant lateral shift⁷. Of 1776 patients presenting at a back pain clinic in England, 100 (5.6%) had a gravity-induced list². In a Finnish chronic back population, 22 of 39 patients (56%) randomly recruited into a reliability study had a relevant lateral shift⁸, and in a study of consecutive chronic back pain patients in the US, 36% had a relevant lateral shift⁹.The lateral shift can be either to the left or the right side^8,10–12 and may be towards the dominant side of pain (ipsilateral) or away from the side of the pain (contralateral). The majority of affected patients have a contralateral shift^3,11,13. Occasionally, the shift may change from side to side, and this has been termed an alternating scoliosis¹⁴. The lateral shift may be explained either as avoidance of compression or irritation of a spinal nerve either actively or reflexively through muscle spasm^4,15–17, or as aberrant disk mechanics where a protrusion or herniation acts as a space-occupying phenomenon pushing the trunk away from the painful mass^2,3,10,18 in a contralateral shift presentation or collapse of the upper vertebral body into a large annular fissure producing an ipsilateral shift presentation^3,18. Although the exact cause of the problem is usually unknown in any given patient, it is frequently and strongly associated with intervertebral disc pathology^2,3,10,13,19.While it has been stated that the presence of a lateral shift carries a poor prognosis with conservative care², McKenzie has claimed that about 90% respond rapidly to manual correction³, especially if the shift is contralateral. It has been reported that a lateral shift associated with a positive cross-leg straight leg raise test carries a poor prognosis with conservative care or following discectomy^20–22. The McKenzie method of mechanical diagnosis and therapy (MDT) is one of the most common systems used in the management of spinal pain conditions^23,24. In patients with a list, the method of manual correction has been shown to result in superior outcomes compared to a control treatment of nonspecific massage and general back care advice¹.This case study (with a supported video clip available at jmmtonline.com/) describes the examination and manual correction, using the method first described by McKenzie³, in a patient with a large right-side contralateral shift. Progressive treatment is outlined including return to full high-level athletic function. The supplemental video allows visualization of the detailed instruction in maintenance and prophylaxis, and the interaction with the patient.     

Long-Term Cardiovascular Risk in Type 2 Diabetic Compared With Nondiabetic First Acute Myocardial Infarction Patients: A population-based cohort study in southern Europe

OBJECTIVE

The aim of this study was to determine whether long-term cardiovascular risk differs in type 2 diabetic patients compared with first acute myocardial infarction patients in a Mediterranean region, considering therapy, diabetes duration, and glycemic control.

RESEARCH DESIGN AND METHODS

A prospective population-based cohort study with 10-year follow-up was performed in 4,410 patients aged 30–74 years: 2,260 with type 2 diabetes without coronary heart disease recruited in 53 primary health care centers and 2,150 with first acute myocardial infarction without diabetes recruited in 10 hospitals. We compared coronary heart disease incidence and cardiovascular mortality rates in myocardial infarction patients and diabetic patients, including subgroups by diabetes treatment, duration, and A1C.

RESULTS

The adjusted hazard ratios (HRs) for 10-year coronary heart disease incidence and for cardiovascular mortality were significantly lower in men and women with diabetes than in myocardial infarction patients: HR 0.54 (95% CI 0.45–0.66) and 0.28 (0.21–0.37) and 0.26 (0.19–0.36) and 0.16 (0.10–0.26), respectively. All diabetic patient subgroups had significantly fewer events than myocardial infarction patients: the HR of cardiovascular mortality ranged from 0.15 (0.09–0.26) to 0.36 (0.24–0.54) and that of coronary heart disease incidence ranged from 0.34 (0.26–0.46) to 0.56 (0.43–0.72).

CONCLUSIONS

Lower long-term cardiovascular risk was found in type 2 diabetic and all subgroups analyzed compared with myocardial infarction patients. These results do not support equivalence in coronary disease risk for diabetic and myocardial infarction patients.The prevalence of diabetes is reaching epidemic proportions in developed countries (1). For example, the U.S. has 18 million diabetic patients, Spain has >2 million diabetic patients, and management of the disease costs >$132 and >$3.3 billion per year, respectively (2).Some studies (3–5), several of them with great influence on important guidelines for cardiovascular prevention (3), suggest that the cardiovascular risk of diabetic patients is similar to that of coronary heart disease secondary prevention patients. Other reports, however, do not confirm these observations (6–10).Part of the discrepancy may stem from differences in the duration of diabetes, type of treatment, and baseline glucose control of diabetic patients included in the studies (3–5). These limit comparability, given the fact that time of evolution and treatment required to attain appropriate glycemic control are key determinants of prognosis (10–16).Among population-based cohort studies that compared the prognosis of diabetic patients with that of myocardial infarction patients without diabetes (3–10), only two analyzed the role of diabetes duration (11,12). Even these studies did not include unstable angina among the end points and risk was not stratified by type of treatment. To our knowledge, the effect of type 2 diabetes on coronary heart disease incidence has barely been studied in southern Europe, a region known for low cardiovascular mortality (17). The aim of this study was to determine whether long-term cardiovascular risk differed between type 2 diabetic patients and first acute myocardial infarction patients and to assess the influence of diabetes duration, type of treatment, and glycemic control at baseline.     

��-Cell�CMediated Signaling Predominates Over Direct ��-Cell Signaling in the Regulation of Glucagon Secretion in Humans

OBJECTIVE

Given evidence of both indirect and direct signaling, we tested the hypothesis that increased β-cell–mediated signaling of α-cells negates direct α-cell signaling in the regulation of glucagon secretion in humans.

RESEARCH DESIGN AND METHODS

We measured plasma glucagon concentrations before and after ingestion of a formula mixed meal and, on a separate occasion, ingestion of the sulfonylurea glimepiride in 24 basal insulin-infused, demonstrably β-cell–deficient patients with type 1 diabetes and 20 nondiabetic, demonstrably β-cell–sufficient individuals; the latter were infused with glucose to prevent hypoglycemia after glimepiride.

RESULTS

After the mixed meal, plasma glucagon concentrations increased from 22 ± 1 pmol/l (78 ± 4 pg/ml) to 30 ± 2 pmol/l (103 ± 7 pg/ml) in the patients with type 1 diabetes but were unchanged from 27 ± 1 pmol/l (93 ± 3 pg/ml) to 26 ± 1 pmol/l (89 ± 3 pg/ml) in the nondiabetic individuals (P < 0.0001). After glimepiride, plasma glucagon concentrations increased from 24 ± 1 pmol/l (83 ± 4 pg/ml) to 26 ± 1 pmol/l (91 ± 4 pg/ml) in the patients with type 1 diabetes and decreased from 28 ± 1 pmol/l (97 ± 5 pg/ml) to 24 ± 1 pmol/l (82 ± 4 pg/ml) in the nondiabetic individuals (P < 0.0001). Thus, in the presence of both β-cell and α-cell secretory stimuli (increased amino acid and glucose levels, a sulfonylurea) glucagon secretion was prevented when β-cell secretion was sufficient but not when β-cell secretion was deficient.

CONCLUSIONS

These data indicate that, among the array of signals, indirect reciprocal β-cell–mediated signaling predominates over direct α-cell signaling in the regulation of glucagon secretion in humans.The regulation of pancreatic islet α-cell glucagon secretion is complex (1–10). It involves direct signaling of α-cells (1) and indirect signaling of α-cells by β-cell (2–6) and δ-cell (7) secretory products, the autonomic nervous system (8,9), and gut incretins (10).Appropriate glucagon secretory responses occur from the perfused pancreas (3,5) and perifused islets (2). Low plasma glucose concentrations stimulate glucagon secretion from the transplanted (i.e., denervated) human pancreas (11) and the denervated dog pancreas (12). Therefore, we have focused on the intraislet regulation of glucagon secretion. Furthermore, because selective destruction of β-cells results in loss of the glucagon response to hypoglycemia in type 1 diabetes (13), and partial reduction of the β-cell mass in minipigs results in impaired postprandial suppression of glucagon secretion (14), we have focused on the role of β-cell–mediated signaling in the regulation of glucagon secretion.Findings from studies of the perfused rat (3,4) and human (5) pancreas, rats in vivo (6), rat islets (2), isolated rat α-cells (2), and humans (15–18) have been interpreted to indicate that a β-cell secretory product or products tonically restrains basal α-cell glucagon secretion during euglycemia and that a decrease in β-cell secretion, coupled with low glucose concentrations at the α-cells, signals an increase in glucagon secretion in response to hypoglycemia. Parenthetically, the relative roles of the candidate β-cell secretory products (insulin, zinc, γ-aminobutyric acid, and amylin, among others) (2) that normally restrain α-cell glucagon secretion remain to be determined. However, that interpretation rests, in part, on results of studies in isolated rat α-cells (2), which are debated (1), and on the evidence that the islet microcirculation flows from β-cells to α-cells to δ-cells (4), which is also debated (19). Furthermore, it does not address the plausible possibility that a decrease in intraislet δ-cell somatostatin secretion might also signal an increase in α-cell glucagon secretion during hypoglycemia (7).Given that interpretation, it follows that an increase in β-cell secretion would signal a decrease in glucagon secretion in the postprandial state (14). The concept is an interplay of indirect reciprocal β-cell–mediated signaling of α-cells and of direct α-cell signaling in the regulation of glucagon secretion.There is, in our view, compelling evidence that, among other mechanisms, both indirect reciprocal β-cell–mediated signaling of α-cells (2–6) and direct α-cell signaling (1) are involved in the regulation of glucagon secretion by nutrients, hormones, neurotransmitters, and drugs. Given that premise, we posed the question: Which of these predominates in humans? Accordingly, we tested the hypothesis that increased β-cell–mediated signaling of α-cells negates direct α-cell signaling in the regulation of glucagon secretion in humans. To do so, we measured plasma glucagon responses to ingestion of a mixed meal and, on a separate occasion, to ingestion of the sulfonylurea glimepiride in patients with type 1 diabetes and in nondiabetic individuals. We conceptualized patients with type 1 diabetes as a model of α-cells isolated from β-cells because their β-cells had been destroyed but they have functioning α-cells. (Their α-cells are not, of course, isolated from other islet cells, including δ-cells.) Increased plasma amino acid and glucose levels after a mixed meal and sulfonylureas normally stimulate β-cell secretion; increased plasma amino acid and perhaps glucose (2) levels after a mixed meal and sulfonylureas (1) stimulate α-cell secretion. Our hypothesis predicts that such factors that normally stimulate both β-cells and α-cells would stimulate glucagon secretion in patients with type 1 diabetes but not in nondiabetic individuals, i.e., in the virtual absence and the presence of β-cell function, respectively. Indeed, a mixed meal (20,21) and the secretagogues tolbutamide (22), glyburide (23), and repaglinide (23) have been reported to raise plasma glucagon concentrations in patients with type 1 diabetes, but all of those studies lacked nondiabetic control subjects.     

Effect of Pharmacological Treatment of Depression on A1C and Quality of Life in Low-Income Hispanics and African Americans With Diabetes: A randomized, double-blind, placebo-controlled trial

OBJECTIVE

To determine whether pharmacological treatment of depression in low-income minorities with diabetes improves A1C and quality of life (QOL).

RESEARCH DESIGN AND METHODS

This was a 6-month, randomized, double-blind, placebo-controlled trial. Patients were screened for depression using Whooley''s two-question tool at a county diabetes clinic. Depression was confirmed (or not) with the Computerized Diagnostic Interview Survey (CDIS) software program, and the severity of depression was assessed monthly by the Hamilton Depression Scale (HAM-D). Depressed subjects with A1C levels ≥8.0% were randomly assigned to receive either sertraline or placebo. Diabetes care was provided by nurses following detailed treatment algorithms who were unaware of therapy for depression.

RESULTS

A total of 150 subjects answered positively to at least one question on Whooley''s questionnaire. The positive predictive value for depression diagnosed by CDIS was 69, 67, and 84% for positive answers to question 1 only, question 2 only, or both, respectively. Of the 89 subjects who entered the study, 75 completed. An intention-to-treat analysis revealed significant differences between baseline and 6 months in HAM-D and pain scores, QOL, and A1C and systolic blood pressure levels in both groups, with no differences between groups for the first three but a significantly greater decrease with sertraline in A1C and systolic blood pressure levels. Changes in HAM-D scores and A1C levels were significantly correlated in all subjects (P = 0.45 [P < 10⁻⁶]).

CONCLUSIONS

In this low-income minority population, pharmacological treatment of depression significantly improved A1C and systolic blood pressure levels compared with placebo.The prevalence of depression among people with diabetes is more than twice that of the general population (1). Coexistence of depression in persons with diabetes is associated with worse glycemic control (2), which may be due to less adherence to self-care behaviors and medications (3). Eventually, there is increased morbidity (4) and mortality (5) and higher medical costs (6).The prevalence of untreated depression in people with diabetes is higher in minorities (1). Yet, screening for and treating depression are less common in this population (7). Very little research has been published on diabetes and depression with a focus on minority populations, who have significant disparities in outcomes (8), such as higher A1C levels (9), increased rates of complications (10), and more severe depression (8).Depression is associated with worse glycemic control (2). Some studies have evaluated whether treatment of depression will improve A1C levels (11–20). However, these drug studies were open label, were of short duration, and/or were conducted in highly educated (more than high school education) Caucasian populations. Most showed that although depression was improved, A1C levels were not. We sought to determine whether use of antidepressants in a minority population with uncontrolled diabetes improved their A1C levels, quality of life (QOL), and depression compared with placebo.