Association of stress proteins with autoantigens: a possible mechanism for triggering autoimmunity?

Patterns of autoantibody production are diagnostic of many autoimmune disorders; the recent observation of additional autospecificities towards stress-induced proteins may also provide insight into the mechanisms by which such responses arise. Grp78 (also known as BiP) is a target of autoaggressive B and T cell responses in our murine model of anti-Ro (SS-A) autoimmunity and also in rheumatoid arthritis. In this report we demonstrate reciprocal intermolecular spreading occurs between Ro52 and Grp78 in immunized mice, reflecting physiological association of these molecules in vivo. Moreover, we provide direct biochemical evidence that Grp78 associates with the clinically relevant autoantigen, Ro52 (SS-A). Due to the discrete compartmentalization of Ro52 (nucleocytoplasmic) and Grp78 (endoplasmic reticulum; ER) we propose that association of these molecules occurs either in apoptotic cells, where they have been demonstrated indirectly to co-localize in discrete apoptotic bodies, or in B cells themselves where both Ro52 and Grp78 are known to bind to immunoglobulin heavy chains. Tagging of molecules by association with Grp78 may facilitate receptor mediated phagocytotsis of the complex; we show evidence that exogenous Grp78 can associate with cell surface receptors on a subpopulation of murine splenocytes. Given the likelihood that Grp78 will associate with viral glycoproteins in the ER it is possible that it may become a bystander target of the spreading antiviral immune response. Thus, we propose a model whereby immunity elicited towards Grp78 leads to the selection of responses towards the Ro polypeptides and the subsequent cascade of responses observed in human disease.     

Audit of an inpatient neurology consultation service in a tertiary referral centre: value of the consulting neurologist

The Mater Misericordiae Hospital is a 575-bed tertiary referral centre with busy medical and surgical subspecialty services (including the national cardiac, cardiothoracic, spinal cord injury and pulmonary hypertension units). An audit of in-patient referrals to a neurology service was carried out over the twelve-month period of January to December 2002 inclusively. Five hundred and seventy seven inpatients were evaluated and managed in conjunction with the referring services. Consultation by the neurological service led to a significant contribution in the management of clinical cases in one of three ways: establishing a de novo diagnosis in patients admitted with active neurological symptoms where no working diagnosis exists (40.7% of referrals), significant alteration in diagnosis where the referring service have already established a specific working diagnosis (11.1% of referrals), or offering advice in the ongoing management of active neurological symptoms when the diagnosis is historically established and secure (48.2% of referrals). In order of frequency the most common reason for referral was stroke (131 cases (22.7%)), seizures unrelated to alcohol (59 cases (10.2%)), alcohol-related neurological problems (55 cases (9.5%)), movement disorders (41 cases (7.1%)), neuromuscular (40 cases (6.9%)), coma (35 cases (6%)), disorders of cognition (31 cases (5.3%)), acute headache (28 case (4.8%)) and functional neurological syndromes (26 cases (4.5%)). This audit highlights the value of a consulting neurology service in a multidisciplinary tertiary referral setting.     

Repeat consultations after antibiotic prescribing for respiratory infection: a study in one general practice.

BACKGROUND. Several new antibacterial drugs have been introduced in the last 10 years with the aim of improved treatment of respiratory tract infection. AIM. The study set out to use repeat consultations as a measure of the outcome of antibiotic treatment for respiratory tract infection, and to develop a simple model for discussion of the cost effectiveness of alternative antibiotic treatments. METHOD. All consultations to one practice during a single winter were reviewed by one general practitioner. RESULTS. A total of 1140 patients had acute symptoms suggestive of respiratory infection. Of these, 899 patients (79%) were prescribed antibiotics at the first consultation and 160 of the 899 patients (18%) returned for one or more repeat consultations; only nine repeat consultations were due to adverse effects of the antibiotics prescribed. Only two patients were admitted to hospital for respiratory symptoms following initial antibiotic therapy and both patients had additional reasons for their admission. Using the highest estimates, the cost of a repeat consultation was found to be 28.54 pounds. These data were used to calculate how much more might be spent on more effective antibiotics at the first consultation. It would be difficult to justify increasing the cost of antibiotic treatment by more than 5 pounds per patient, even if the new treatment were 100% effective and all repeat consultations were due to treatment failure (5 pounds is equal to 28.54 pounds x 0.18, which is the maximum cost of a repeat consultation multiplied by the proportion of patients prescribed antibiotics who make repeat consultations). CONCLUSION. From these results and a review of the literature it can be concluded that new antibacterial drugs will have to be carefully targeted if they are to prove cost effective in practice. Other methods for reducing repeat consultation merit investigation.     

Hydrogen peroxide Modulates Ca2+-Activation of Single permeabilized Fibres from Fast- and Slow-twitch Skeletal Muscles of Rats

We examined the effects of redox modulation on single membrane-permeabilized fibre segments from the fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus muscles of adult rats to determine whether the contractile apparatus was the redox target responsible for the increased contractility of muscles exposed to low concentrations of H₂O₂. The effects of H₂O₂ on maximum Ca²⁺-activated force were dose-dependent with 30 min exposure to 5 mM H₂O₂ causing a progressive decrease by 22 ± 3 and 13 ± 2% in soleus and EDL permeabilized muscle fibres, respectively. Lower concentrations of exogenous H₂O₂ (100 M and 1 mM) had no effect on maximum Ca²⁺-activated force. Subsequent exposure to the reductant dithiothreitol (DTT, 10 mM, 10 min) fully reversed the H₂O₂-induced depression of force in EDL, but not in soleus muscle fibres. Incubation with DTT alone for 10 min did not alter Ca²⁺-activated force in either soleus or EDL muscle fibres. The sensitivity of the contractile filaments to Ca²⁺ (pCa₅₀) was not altered by exposure to any concentration of exogenous H₂O₂. However, all concentrations of H₂O₂ diminished the Hill coefficient in permeabilized fibres from the EDL muscle, indicating that the cooperativity of Ca²⁺ binding to troponin is altered. H₂O₂ (5 mM) did not affect rigor force, which indicates that the number of crossbridges participating in contraction was not reduced. In conclusion, H₂O₂ may reduce the maximum Ca²⁺ activated force production in skinned muscle fibres by decreasing the force per crossbridge.     

Molecular heterogeneity and fine specificity of BALB/c antibodies elicited by isologous myeloma protein.

BALB/c mice immunized with the isologous myeloma protein MOPC-315 (M315; α, λ₂) develop antibodies most of which are directed to idiotypic antigens (Id315) located in or near the CNP binding sites of M315, In order to more precisely establish the fine specificity of anti-Id315 antibodies, and to obtain an estimate of the size of the BALB/c anti-Id315 repertoire, we examined anti-Id315 antibodies from individual mice by analytical isoelectric focusing followed by autoradiography. ¹²⁵I-labeled probes were prepared from purified mildly reduced and alkylated M315 protein (RA315) (7 S monomer), Fab'315, Fv315, L315, H315, DNP affinity-labeled RA315, mildly reduced and alkylated MOPC-460 (RA460; 7 S; α, k, Fab'460, H460, and DNP affinity-labeled RA460. We observed that (a) the majority of BALB/c antibodies elicited by immunization with RA315 are specific for idiotypic antigens in the variable region which are rendered inaccessible in the presence of DNP-hapten; (b) distinctly separate antibodies are specific for idiotypic antigens also located in the variable regions but which are not influenced by DNP hapten; (c) about 30 % of BALB/c mice develop antibodies which appear to be specific for a determinant located in the second or third, homology regions of the constant region of the α chain which is not influenced by DNP hapten, and which is also present in the same region of H460; (d) none of the antibodies elicited by M315 recognize free L315; (e) the total antibody response is quite restricted; (f) shared spectrotypes are common between individual mice; and (g) unique or infrequently shared spectrotypes do occur. These studies demonstrate, by a direct technique, the fine specificity and the clonal and molecular heterogeneity of the B cell response induced by immunization with RA315.     

Reproduction and thermoregulation in Peromyscus: Effects of chronic short days

Seven groups of laboratory reared Connecticut P. leucopus were exposed to a 9L:15D photoperiod for either 6, 9, 12, 20, 25, 32, or 36 weeks. An eighth group was maintained on 16L:8D. During the final 6 weeks all mice were cold exposed (13°C). Substantial reproductive regression occurred in females following 6 weeks exposure to 9L:15D relative to 16L:8D animals. In males, a slight decrease in testicular weight occurred following 6 weeks on 9L:15D; this effect was pronounced by 9 weeks, along with a decrease in seminal vesicle weight. Reproductive recrudescence occurred in females by week 32 and in males by week 36. Between 10 and 12 weeks on 9L:15D mice exhibited increases in nesting, incidence of daily torpor, and presence of the winter molt. These increases persisted through 36 weeks on 9L:15D. An increase in the interscapular brown fat pad occurred between 12 and 25 weeks. Reproductive and thermoregulatory characters respond differently to prolonged exposure to a short day photoperiod in this species.     

Autoradiographic localization of kappa opiate receptors in CNS taste and feeding areas

Recent evidence suggests that kappa opiate receptors may play a key role in the regulation of appetite. Such evidence implies that kappa receptors might be localized within specific brain areas known to regulate ingestive behaviors. On the basis of this implication we employed an in vitro film autoradiographic technique using 3H-ethylketocyclazozine as ligand to identify putative kappa receptors within CNS "taste" nuclei and surrounding areas. Coronal cryostat sections of rat brain were incubated with ligand in the presence of D-Ala2, D-Leu5-enkephalin (DADLE) and morphine, apposed to LKB Ultrofilm for 60 days, processed and kappa receptor densities evaluated with the aid of a hand held photometer and video image analyzer. Highest kappa receptor densities were found within various gustatory and feeding sites including the rostral pole of the nucleus of the solitary tract, parabrachial nuclei, ventral posterior and medial portions of the thalamus, medial hypothalamus, medial nuclei of the amygdala and bed nucleus of the stria terminalis. Various other midline and medial limbic areas also showed significant kappa densities.     

Comparison of efficacy and safety of daily oral L-arginine and PDE5Is alone or combination in treating erectile dysfunction: A systematic review and meta-analysis of randomised controlled trials

The meta-analysis was performed to assess the efficacy and safety of daily oral L-arginine and phosphodiesterase type 5 inhibitors (PDE5Is) alone or combination in treating patients with erectile dysfunction (ED). We performed a search of randomised controlled trials in the following databases: PubMed, EMBASE and Cochrane Library databases. Four articles including 373 patients were studied. Erectile functions were significantly improved in three therapy groups compared with baseline. Patients who received the combination of L-arginine and PDE5Is showed significant improvement compared to those treated with L-arginine and PDE5Is alone, as assessed by sexual function index (p <0.00001 and p =0.005, respectively) and total testosterone (p <0.00001 and p =0.0007, respectively). Furthermore, patients who treated with PDE5Is alone exhibited the better efficacy than those treated with L-arginine alone in respects of sexual function index (p <0.00001) and total testosterone (p =0.0001). However, the combination of L-arginine and PDE5Is had no obvious difference relative to PDE5Is alone in terms of various adverse events (AEs). Conclusively, compared with monotherapy, the combination of L-arginine and PDE5Is showed a greater improvement of sexual function and total testosterone, and did not significantly increase the AEs. Besides, PDE5Is alone revealed a better effect than those treated with L-arginine alone for patients with ED.