Bacterial superantigen enhances cytokine production by T-helper lymphocyte subset-2 cells and modifies glomerular lesions in experimental immunoglobulin a nephropathy

Background The purpose of this study was to examine the effects of bacterial suporantigens, which can derange the immune response and contribute to the renal lesions of immunoglobulin A (lgA) nephropathy. Methods Twenty-five micrograms of a bacterial superantigen, staphylococcal enterotoxin B (SEB), was injected into IgA nephropathy-prone ddY mice intrathymically when they reached 6 weeks of age. Evaluation included measurement of albumin excretion in urine, immunoglobulin concentration, and lymphokine production in vitro, as well as analysis of T-cell receptor expression in splenic T-cell subsets and examination of renal histology by light and fluorescence microscopy. Results At 40 weeks of age, the serum level of IgA in these mice was substantially increased and the number of Vβ8⁺ CD4⁺splenic T-cells was significantly decreased compared with measurements in untreated controls. Both control and SEB-treated mice excreted less than 30 μg/mL of urinary albumin. In mice given SEB, the amount of interleukin 2 (IL-2) and tumor necrosis factor-α (T helper 1 [Th1]-type cytokines) produced by the in vitro-stimulated lymphocytes significantly decreased. whereas that of interleukin 4 (IL-4) and interleukin 6 (IL-6) (Th2-type cytokines) markedly increased compared with measurements in control mice. At 40 weeks of age, mice given SEB showed marked glomerular hypercellularity and enhanced glomerular C3 deposition by renal histology, compared with control mice. Conclusion These results suggest that bacterial superantigen SEB may modify glomerular lesions through activating Th2 cells, while inducing deletion of Th1 cells in this experimental model.     

Cuboidal epithelium lining of the parietal layer of Bowman's capsule in Afghan pikas (Ochotona rufescens rufescens)

Kidneys of 64 Afghan pikas (Ochotona rufescens rufescens) were examined histologically. Seven of 21 males and two of 21 females over 6 months of age had a cuboidal epithelium lining of the parietal layer of Bowman's capsule.     

Ross procedure in an infant weighing 4.5 kg

A 6 month-old male infant (weight: 4.5 kg) with congenital aortic stenosis underwent aortic valve replacement with a pulmonary autograft (Ross procedure). The right ventricular outflow tract (RVOT) was reconstructed with a polytetrafluoroethylene (PTFE)-valved equine pericardial conduit. At the age of 5, re-RVOT reconstruction with an equine pericardial patch bearing a PTFE monocusp was required because of severe pulmonary stenosis resistant to 2 attempts of percutaneous transluminal pulmonary valvotomy. Currently, at the age of 8, the degree of aortic regurgitation is trivial and the pulmonary autograft is free of functional deterioration despite somatic growth.     

AUGMENTED ENDOGENOUS NITRIC OXIDE PRODUCTION IN PARTIAL PORTAL VEIN-LIGATED RATS

1. Endothelium-derived nitric oxide (NO) is a potent vasodilator. Because the body oxidizes it to nitrate ions, NO₃-, measurement of the serum concentration and the urinary excretion of NO₃- may be an index for endogenous NO. We investigated the role of NO on hyperdynamic circulation in cirrhotic and partial portal vein-ligated rats by measuring NO₃. 2. Liver cirrhosis was induced by administration of thioacetamide. Systemic and splanchnic haemodynamics and splenic-systemic shunting were determined by tracer microspheres. The concentration of NO₃- was measured by using high-performance liquid chromatography with an anion-column. 3. We found that systemic and splanchnic hyperdynamic circulation existed to almost the same extent in cirrhotic and in portal vein-ligated rats as compared to the controls and sham-operated rats, respectively. Splenic-systemic shunting was markedly greater in portal vein-ligated rats than in cirrhotic rats. 4. Serum NO₃- levels and urinary excretion of NO₃- in cirrhotic rats tended to increase as compared to the controls. On the other hand, the levels in portal vein-ligated rats were significantly increased as compared to those of the sham-operated rats, and were significantly and negatively correlated to the splanchnic arterial resistance and total vascular resistance. The amount of urinary excretion of NO₃- significantly correlated to splenic-systemic shunting (r = 0.61, P<0.05) only in portal vein-ligated rats. 5. We suggest that these high levels of NO₃- in portal vein-ligated rats relate to the extensive formation of porto-collateral vasculature or acute changes in systemic and splanchnic haemodynamics due to portal vein-ligation.     

Effects of sodium nitroprusside (MR7S1) and nitroglycerin on the systemic,renal, cerebral,and coronary circulation of dogs anesthetized with enflurane

Summary In beagle dogs anesthetized with enfluranenitrous oxide, effects of sodium nitroprusside (SNP; MR7S1) and nitroglycerin (NTG) on hemodynamics and main organ circulation were studied to evaluate their effectiveness and safety as hypotensive agents during anesthesia. SNP (MR7S1) infusion (1–10 g/kg/min) decreased arterial blood pressure in a dose-dependent manner. The hypotension was stable during the infusion. After discontinuation of infusion, the blood pressure rapidly returned to the initial level. The hypotension was associated with decreases in cardiac output and total peripheral resistance. NTG infusion (3–10 g/kg/min) decreased arterial blood pressure, too, but the hypotension was less marked and not dose dependent, and the recovery was slower. Neither drug changed the heart rate. Infusion of SNP (MR7S1) and NTG did not change the hypotension induced by the injection of adenosine, SNP, and NTG. Furthermore, cerebral blood flow, cerebral oxygen consumption, and renal blood flow were unchanged during the hypotension produced by either drug. Coronary blood flow was decreased, but this was due to decreases in cardiac oxygen consumption. In conclusion, SNP (MR7S1) is superior to NTG as a hypotensive agent during anesthesia in efficacy, clear dose dependency, and rapid recovery. The hypotension induced by NTG as well as SNP (MR7S1) seems to have no undesirable effects on the circulation of important organs.     

Simulation studies of data classification by artificial neural networks: Potential applications in medical imaging and decision making

Artificial neural networks are being investigated in the field of medical imaging as a means to facilitate pattern recognition and patient classification. In the work reported here, the effects of internal structure and the nature of input data on the performance of neural networks were investigated systematically using computer-simulated data. Network performance was evaluated quantitatively by means of receiver operating characteristic analysis and compared with the performance of an ideal statistical decision maker. We found that the relatively simple neural networks investigated in this study can perform at the level of an ideal decision maker. These simple networks were also found to learn accurately even when the training data are extremely unbalanced with respect to the prevalence of actually positive cases and to differentiate input data patterns by recognizing their unique characteristics.     

Bcl11b is required for differentiation and survival of alphabeta T lymphocytes

The gene Bcl11b, which encodes zinc finger proteins, and its paralog, Bcl11a, are associated with immune-system malignancies. We have generated Bcl11b-deficient mice that show a block at the CD4-CD8- double-negative stage of thymocyte development without any impairment in cells of B- or gammadelta T cell lineages. The Bcl11b-/- thymocytes showed unsuccessful recombination of V(beta) to D(beta) and lacked the pre-T cell receptor (TCR) complex on the cell surface, owing to the absence of Tcrb mRNA expression. In addition, we saw profound apoptosis in the thymus of neonatal Bcl11b-/- mice. These results suggest that Bcl11b is a key regulator of both differentiation and survival during thymocyte development.