Skin incision translation in total knee arthroplasty: the difference between flexion and extension

Scar location and point loading of the scar after total knee arthroplasty are common postoperative concerns for patients and physicians. A frequent problem is discomfort associated with the incision. We evaluated 40 knees to better understand the association of the tibial tubercle with the overlying skin in both flexion and extension. Our results revealed lateral translation of the skin overlying the tibial tubercle in 100% of our volunteers as the knee is flexed and the tibia internally rotates. The average amount of lateral translation measured 9.7 mm. This could have a significant impact on point loading of the scar if an anterior midline incision for total knee arthroplasty is planned in extension.     

Resistance to change of alcohol self-administration: effects of alcohol-delivery rate on disruption by extinction and naltrexone

A common finding in resistance to change research with food-maintained operant behavior is that the persistence of behavior depends on the rate of reinforcement delivered in the context in which the behavior occurs. The present experiment evaluated the effects of rate of response-dependent alcohol delivery on the resistance to change of rats' alcohol self-administration in the face of disruption produced by extinction and a range of doses of naltrexone (1.0, 3.0, 10.0 mg/kg, subcutaneous). Rats responded for a 10% alcohol solution in a multiple schedule of reinforcement arranging a higher rate of alcohol delivery (variable interval 15 s) in the presence of one stimulus and a lower rate of alcohol delivery (variable interval 45 s) in the presence of another stimulus. Baseline response rates and resistance to extinction were higher in the presence of the stimulus associated with higher rates of alcohol delivery. This finding is consistent with studies of the resistance to change of food-maintained behavior. The rate of alcohol delivered in the components, however, did not systematically affect resistance to disruption by naltrexone. One interpretation of this finding from the perspective of behavioral momentum theory is that naltrexone may decrease the impact of alcohol-associated stimuli on the persistence of drinking by reducing sensitivity to the relative reinforcement conditions arranged in the presence of different stimuli.     

From battlefront to homefront: creation of a civilian walking blood bank

Hemorrhagic shock remains the leading cause of preventable death on the battlefield, despite major advances in trauma care. Early initiation of balanced resuscitation has been shown to decrease mortality in the hemorrhaging patient. To address transfusion limitations in austere environments or in the event of multiple casualties, walking blood banks have been used in the combat setting with great success. Leveraging the success of the region-wide whole blood program in San Antonio, Texas, we report a novel plan that represents a model response to mass casualty incidents.     

Identification of CD47/integrin-associated protein and alpha(v)beta3 as two receptors for the alpha3(IV) chain of type IV collagen on tumor cells.

Previous studies from our laboratories demonstrated that a peptide from the noncollagenous domain of the alpha3 chain of basement membrane collagen (COL IV), comprising residues 185-203, inhibits polymorphonuclear leukocyte activation and melanoma cell proliferation independently of its ability to promote cell adhesion; these properties require the presence of the triplet -SNS- at residues 189-191 (J. C. Monboisse et al., J. Biol. Chem., 269: 25475-25482, 1994; J. Han et al., J. Biol. Chem., 272: 20395-20401, 1997). More recently, we demonstrated that native COL IV and -SNS-containing synthetic peptides (10 microg/ml) added to culture medium inhibit the proliferation of not only melanoma cells but also breast, pancreas, and stomach tumor cells up to 82% and prostate tumor cells by 15%. This inhibition was shown to be dependent on a COL IV- or peptide-induced increase in intracellular cAMP (T. A. Shahan et al., Connect. Tissue Res., 40: 221-232, 1999). Attempts to identify the putative receptor(s) on tumor cells led to the isolation of five proteins (Mr 33,000, 52,000, 72,000, 95,000, and 250,000) from melanoma and prostate cells by affinity purification with the alpha3(IV)179-208 peptide. The Mr 52,000, 95,000, and 250,000 proteins were shown to be CD47/integrin-associated protein(IAP), the integrin beta3 subunit, and the alpha(v)beta3 integrin complex, respectively. The Mr 33,000 and 72,000 proteins have not yet been identified. To confirm the specificity of ligand binding to the receptors, cell membranes from either melanoma or prostate tumor cells were pretreated with the unlabeled ligand alpha3(IV)187-191 (-YYSNS-); alternatively, the peptide was pretreated with a peptide-reactive monoclonal antibody (A5D7) before receptor isolation. These treatments inhibited the purification of CD47/IAP, the integrin beta3 subunit, and the alpha(v)beta3 integrin complex from tumor cells. Furthermore, cells treated with CD47/IAP- or the alpha(v)beta3 integrin-reactive antibodies prevented the alpha3(IV)185-203 peptide from inhibiting cell proliferation and the subsequent rise in intracellular cAMP. Pretreating cells with the alpha3(IV)187-191 (-YYSNS-) peptide also inhibited their adhesion to the alpha3(IV)185-203 peptide substrate, whereas the inactive alpha1(IV)185-203 peptide, from the same region of the alpha1 chain as the alpha3(IV)185-203 peptide, had no effect. Incubation of cells with either CD47/IAP and/or alpha(v)beta3 integrin-reactive antibodies inhibited their adhesion to the alpha3(IV)185-203 peptide, whereas antibodies to the beta1 and beta2 integrin subunits were without effect. These data suggest that ALC-COL IV, through its alpha3(IV) chain, inhibits tumor cell proliferation using the receptors CD47/IAP and the alpha(v)beta3 integrin.     

Carotid plaque: comparison between visual and grey-scale median analysis

Plaque morphology plays an important prognostic role in the occurrence of cerebrovascular events. Echolucent and heterogeneous plaques, in particular, carry an increased risk of subsequent stroke. Most of the trials emphasizing the relationship between plaque echo structure and stroke risk are based on high-resolution ultrasound (US) using a visual method of classification. More recently, several studies have suggested that the computerized measurement of the grey-scale median (GSM) may evaluate carotid plaque echogenicity more objectively and accurately. We sought to compare these two types of evaluations. We studied 68 consecutive patients, with 86 carotid bifurcation plaques causing 30% to 99% stenosis on duplex scanning. We assessed the GSM of these plaques and compared it to the visually evaluated echogenicity using the five-type classification system with vessel lumen and adventitia as reference structures. Plaque heterogeneity was also studied in a subgroup of 47 patients with 60 carotid stenoses by comparing visual analysis with the GSM method. The mean GSM value of the plaques increased with the plaque type. The difference of echogenicity between the five types of plaques was statistically significant (p < 0.02). We found a good concordance between visual analysis and the GSM method regarding plaque heterogeneity. Our results suggest that the visual evaluation of plaque echogenicity and heterogeneity based on the five-type classification correlates well with the computerized measurement of the GSM. The visual evaluation of carotid plaque remains, therefore, a valuable method in daily clinical practice.     

Nicotine gum as a substitute for cigarettes: a behavioral economic analysis

The present experiment attempted to identify a substitute for cigarette smoking in a laboratory analog of the behavioral economics of drug dependence. The interaction between cigarette consumption and nicotine gum consumption was examined with eight human smokers by increasing the price of cigarettes (i.e. the number of responses required to obtain puffs) across sessions, while the price of concurrently available nicotine gum remained constant. In another phase, the price of nicotine gum was increased while the price of concurrently available cigarettes remained constant. To determine whether the presence of concurrently available nicotine gum influenced cigarette consumption, we also examined the effect of increasing the price of cigarettes on cigarette consumption without available nicotine gum. When cigarettes and nicotine gum were concurrently available, increases in the price of cigarettes increased consumption of nicotine gum. When the price of nicotine gum increased while the price of cigarettes remained constant, smokers nearly exclusively consumed cigarettes. The presence or absence of nicotine gum did not affect the relation between cigarette consumption and cigarette price. The results suggest that nicotine gum can maintain operant behavior of smokers in the laboratory and can function, in a behavioral economic sense, as a weak substitute for cigarette puffs. As a result, nicotine gum may be useful in human laboratory studies of the behavioral economics of reinforcer interactions and their role in drug dependence.     

Autoantibodies in chronic idiopathic urticaria and nonurticarial systemic autoimmune disorders

BackgroundChronic idiopathic urticaria (CU) has been associated with other autoimmune diseases and basophil-activating autoantibodies to FcεRI or IgE. It is unknown whether patients with systemicautoimmune diseases have a similar prevalence of these autoantibodies.ObjectiveTo compare the prevalences of basophil-activating autoantibodies (elevated CU Index) in patients with CU, rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE). Clinical characteristics and laboratory studies were examined for an association with the CU Index.MethodsAdult patients, 27 with CU, 27 with RA, and 26 with SLE, and 20 healthy controls were compared on the basis of the CU Index panel, anti-IgE, and antithyroid antibodies.ResultsThe CU Index values were significantly higher in the CU group when compared with the RA group but not when compared with the SLE group. 33% of CU, 23% of SLE, 3.7% of RA, and 15% of controls had apositive CU Index. Elevated antithyroid antibody levels did not correlate with a positive CU Index in any of the groups. An elevated CU Index in the SLE group was not associated with age, sex, ethnicity, disease severity, or history of atopy.ConclusionThe CU Index values were elevated in patients with CU and SLE. The presence of these autoantibodies did not correlate with disease activity or presence of thyroid antibodies. Functional autoantibodies may not be specific for chronic idiopathic urticaria, and their role in nonurticarial systemic autoimmune diseases requires further investigation.     

Changes in cerebral blood flow during cerebrospinal fluid pressure manipulation in patients with normal pressure hydrocephalus: a methodological study.

The combination of cerebral blood flow measurement using (15)O-water positron emission tomography with magnetic resonance coregistration and CSF infusion studies was used to study the global and regional changes in CBF with changes in CSF pressure in 15 patients with normal pressure hydrocephalus. With increases in CSF pressure, there was a variable increase in arterial blood pressure between individuals and global CBF was reduced, including in the cerebellum. Regionally, mean CBF decreased in the thalamus and basal ganglia, as well as in white matter regions. These reductions in CBF were significantly correlated with changes in the CSF pressure and with proximity to the ventricles. A three-dimensional finite-element analysis was used to analyze the effects on ventricular size and the distribution of stress during infusion. To study regional cerebral autoregulation in patients with possible normal pressure hydrocephalus, a sensitive CBF technique is required that provides absolute, not relative normalized, values for regional CBF and an adequate change in cerebral perfusion pressure must be provoked.