Senescent changes in a neurobiological model system: Cerebellar Purkinje cell electrophysiology and correlative anatomy

A within-subjects design was used to assess age changes in cerebellar Purkinje neurons. Four groups of naive male Sprague-Dawley rats, aged 3, 10, 20, and 28 months, underwent single cell recording for electrophysiological assessment of Purkinje cell firing patterns, followed by perfusion for glyoxylic acid induced catecholamine fluorescence. Cerebellar sections were photographed first by fluorescence microscope for catecholamines, and 2–3 weeks later for quantification of lipofuscin autofluorescence. Finally, these same tissues were treated with cresyl violet and photographed a third time to permit quantitative estimates of age changes in the number of Nissl staining Purkinje neurons. Electrophysiological studies revealed significant effects of age on a number of Purkinje cell firing parameters: in particular, increasing numbers of aberrant, very slow-firing cells were encountered in older animals. These cells showed normal climbing fiber mediated burst activity, but spontaneous simple spike firing rates 3–5 times less than normal. Rats exhibiting the highest numbers of such abnormal cells also exhibited the poorest Nissl staining. Conversely, good Nissl staining of Purkinje neurons in an old rat was a reliable predictor of relatively normal Purkinje cell firing. Lipofuscin was found to accumulate measurably in Purkinje neurons by 20 months of age, and to increase significantly thereafter. Deposition of the substance occurred almost exclusively at the apical pole of the soma. Our data suggest, however, that accumulation of lipofuscin in Purkinje neurons, as well as its reported accumulation in the inferior olive, is not a primary cause of electrophysiological dysfunction. There was no apparent age change in glyoxylic acid induced catecholamine fluorescence nor, in separate pharmacological studies, could any senescent alteration in cerebellar catecholamine levels be found.     

Feeding suppression induced by intra-ventricle III infusion of 1,5-anhydroglucitol

1,5-Anhydroglucitol (1-DG) has been known as an antimetabolic glucose analogue. Using gas chromatography, 1-DG was found to be physiologically present in rat serum. In order to investigate its direct and long-term effects on feeding, 1-DG was infused during the light period into the rat third ventricle in doses of 3.0, 6.0 and 12.0 mumol/rat. Its effects were then compared to those of similarly applied 2-deoxy-D-glucose (2-DG). Following initial hyperphagia, both of these glucose-analogues produced suppressive effects on feeding during the subsequent day throughout the light and dark periods. On the third day after 2-DG injection reduction of feeding did not recover completely to the pretreatment baseline levels, but it did recover after 1-DG. Both 1-DG and 2-DG caused linear dose-related hypophagia, with the slope for 1-DG being about half of that for 2-DG. It is suggested that the delayed hypophagia which followed the initial hyperphagia produced by deoxyglucose was a result of sustained inactivation of the Na-pump due to intracellular ATP deficiency caused by accumulation of deoxy-glucose-6-phosphate.     

Modulation of hu/mu severe combined immunodeficient (SCID) mouse arthritis by local application of human recombinant IL-1β, IL-2 and IL-6

The contribution of interleukins produced by most inflammatory cells to chronic arthritis is not well understood. Therefore, we investigated the influence of several human recombinant interleukins (IL-1β, IL-2 and IL-6) on joint swelling, on the inflammatory process, and on serological parameters in a novel animal model of arthritis, the human/murine SCID arthritis. In this model an arthritis is induced by implanting human synovial tissue from patients with rheumatoid arthritis (RA) into the knee joint of mice with SCID. These mice tolerate the xenogeneic implant and develop a mixed human/murine pannus tissue. The interleukins were injected daily for 7 or 14 days after implantation. IL-1β led to a significant increase in joint swelling. It intensified the inflammatory process accompanied by enhanced migration of murine inflammatory cells into the knee joint. The production of human IL-6 in the transplanted tissue was stimulated through the application of IL-1β, and the serum level of human IL-6 was thus significantly higher than in controls. We could not observe a significant influence of IL-1β on the production of human IgG or IgM by the implant. The application of human IL-2 had a weak effect similar to that of IL-1β, but without statistical significance. Although IL-6 is a good marker for inflammation in RA, the application of recombined human IL-6 had no influence on the inflammatory process in this model.     

The compartment model for chronically implanted voltammetric electrodes in the rat brain

Diazepam (0.4-0.8 mg/kg i.p.) reduced the spontaneous activity in the electromyogram (EMG) recorded from the gastrocnemius-soleus muscle of spastic mutant Han--Wistar rats in a dose-dependent manner. The depressant effect of diazepam (0.8 mg/kg) on the EMG activity was antagonized by Ro 15-1788 (5 mg/kg i.p.) and by picrotoxin (2 mg/kg i.p.), but not by bicuculline (2 mg/kg i.p.). These results suggest that diazepam depresses EMG activity of mutant rats by mechanisms related to the interaction of the drug with GABA-independent benzodiazepine receptors.     

Force- and moment-generating capacities of muscles in the distal forelimb of the horse

A detailed musculoskeletal model of the distal equine forelimb was developed to study the influence of musculoskeletal geometry (i.e. muscle paths) and muscle physiology (i.e. force-length properties) on the force- and moment-generating capacities of muscles crossing the carpal and metacarpophalangeal joints. The distal forelimb skeleton was represented as a five degree-of-freedom kinematic linkage comprised of eight bones (humerus, radius and ulna combined, proximal carpus, distal carpus, metacarpus, proximal phalanx, intermediate phalanx and distal phalanx) and seven joints (elbow, radiocarpal, intercarpal, carpometacarpal, metacarpophalangeal (MCP), proximal interphalangeal (pastern) and distal interphalangeal (coffin)). Bone surfaces were reconstructed from computed tomography scans obtained from the left forelimb of a Thoroughbred horse. The model was actuated by nine muscle-tendon units. Each unit was represented as a three-element Hill-type muscle in series with an elastic tendon. Architectural parameters specifying the force-producing properties of each muscle-tendon unit were found by dissecting seven forelimbs from five Thoroughbred horses. Maximum isometric moments were calculated for a wide range of joint angles by fully activating the extensor and flexor muscles crossing the carpus and MCP joint. Peak isometric moments generated by the flexor muscles were an order of magnitude greater than those generated by the extensor muscles at both the carpus and the MCP joint. For each flexor muscle in the model, the shape of the maximum isometric joint moment-angle curve was dominated by the variation in muscle force. By contrast, the moment-angle curves for the muscles that extend the MCP joint were determined mainly by the variation in muscle moment arms. The suspensory and check ligaments contributed more than half of the total support moment developed about the MCP joint in the model. When combined with appropriate in vivo measurements of joint kinematics and ground-reaction forces, the model may be used to determine muscle-tendon and joint-reaction forces generated during gait.     

Role of group A streptococcal IgG-binding proteins in triggering experimental glomerulonephritis in the rabbit

Our previous studies have indicated that the IgG-binding M-family proteins (IgGBP) of group A streptococci may be involved in eliciting experimental acute poststreptococcal glomerulonephritis (APSGN) in the rabbit. These surface proteins were also found to trigger production of anti-IgG, which might conceivably act to enhance renal deposition of immune complexes (IC). In the present study, a clinical isolate of serotype M22 (strain AL168), an isogenic double mutant deficient for both the IgGBPs Mrp and Emm, as well as mutants deficient in only one of the proteins were tested for capacity to induce glomerulonephritis. Streptococci to be used for injecting rabbits were heat-killed. Surface-bound IgG was removed by 1 M KSCN and cells were then repeatedly washed in PBS before use. Rabbits were injected intravenously with 109 cells three times a week for 8 weeks and, following one month of rest, for another 6 weeks. Deposits of IgG and C3 as well as induced chemokines TNF-alpha, IL-1beta and IL-6 were traced in cryostat sections using specific antibodies and appropriate peroxidase-labelled anti-antibodies. In four rabbits immunized with the double mutant strain, no deposits were found, and as examined by TEM, only subtle and transient renal changes were observed. In contrast, the original strain AL168 induced pronounced inflammatory and degenerative glomerular changes in all four rabbits injected, and deposits of TNF-alpha, IL-1beta and IL-6 were found in mesangial and endothelial cells. Similar deposits and glomerular changes were seen in all eight rabbits injected with the mrp-emm+ mutant and in four out of seven animals receiving the mrp+emm- mutant. There was a highly significant correlation between high levels of circulating anti-IgG and development of APSGN. These results confirm an important role of streptococcal IgGBP in triggering experimental APSGN as earlier proposed by our group.     

Cognitive and behavioural correlates of non‐adherence to HIV anti‐retroviral therapy: Theoretical and practical insight for clinical psychology and health psychology

This cross‐sectional study identified variables associated with protease inhibitor (PI) non‐adherence in 179 patients taking anti‐retroviral therapy. Univariate analyses identified 11 variables associated with PI non‐adherence. Multiple logistic regression modelling identified three predictors of PI non‐adherence: low adherence self‐efficacy and seriousness of non‐adherence and HIV (p < .001), perceived absence of HIV associated illness (p < .01), and use of more than one type of recreational drug (p = .001). The model correctly classified 83.9% of the sample, offers psychologists insight into psychological barriers to treatment adherence to guide interventions for improving adherence, and supports a modified version of the reformulated health belief model.     

Combined total deficiency of C7 and C4B with systemic lupus erythematosus (SLE).

The first inherited combined total deficiency of C7 and C4B complement components associated with SLE is described in a young female. Functional C7 assays showed a homozygous C7 deficiency in the propositus and her sister, and an heterozygous one in their parents. C4 molecular analyses showed that both the propositus and her mother had two HLA haplotypes carrying only C4A-specific DNA sequences and a normal C4 gene number. Thus, only C4A proteins could be expressed, with resultant normal C4 serum levels. The coexistence of a combined complete C7 and C4B deficiency may therefore abrogate essential functions of the complement cascade presumably related to immune complex handling and solubilization despite an excess of circulating C4A. These findings challenge the putative pathophysiological roles of C4A and C4B and stress the need to perform both functional assays and C4 allotyping in patients with autoimmune pathology and low haemolytic activity without low serum levels of a classical pathway complement component.     

An immunochemical procedure to evaluate the degree of desialylation of alpha 1-acid glycoprotein in rat serum

When radial immunodiffusion (RID) and electroimmunodiffusion (EID) were used for the determination of rat alpha 1-acid glycoprotein (alpha 1-AGP) a significant discrepancy in the results was encountered depending on the degree of sialylation. When alpha 1-AGP was desialylated, the amounts estimated by EID were much lower than those actually present as assayed by the RID method. The relationship between the percentage of desialylation of alpha 1-AGP and the percentage of its underestimation by EID relative to RID was determined and a calibration curve was plotted to evaluate the degree of desialylation of rat alpha 1-AGP. When compared to other procedures (rat membrane inhibition assay and isoelectrofocusing), the proposed method was easier to perform and allowed the specific evaluation of the degree of undersialylation of the glycoprotein.     

Cortisol,acth, and biosynthesis of apolipoproteins in rat hepatocytes

The effect of cortisol (5 mg/kg, 5 and 10 days) on biosynthesis of apoproteins of very low density lipoproteins in the liver and on synthesis of apoproteins of very low, low, and high density lipoproteins in blood serum of intact animals was investigatedin vivo. Cortisol, within the periods specified, inhibits biosynthesis of apoproteins of very low density lipoproteins (apo-VLDL) in liver. After adrenalectomy apo-VLDL synthesis is intensified and this effect is abolished during replacement administration, of cortisol. Apoprotein synthesis is activated 5 h after a single injection of cortisol and ACTH; a single dose and prolonged administration of cortisol give opposite results. Investigation of the specific radioactivity of apolipoproteins in the blood serum indicates a change in lipoprotein metabolism: disturbance of conversion of very low density into low density lipoproteins. An important role in the pathogenesis of the hyperlipidemia induced by cortisol within the specified period is played not by increased lipoprotein synthesis in the liver, but by a disturbance of their metabolism in the blood.All-Union Cardiological Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Prosented by Academician of the Academy of Medical Sciences of the USSR E. I. Chazov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 11, pp. 538–540, November, 1978.