Structural evidence for counter-current flow in proximal tubules versus pertitubular capillaries in the rat kidney. Evaluation of the counter-current mechanism between the proximal convoluted tubules and the peritubular capillaries in the rat nephron

BACKGROUND: In spite of the very high exchange of water and solutes between the proximal tubules and the peritubular capillaries, very little is known about flow directions in these two interrelated structures. We therefore developed a morphological technique suitable for the quantitative evaluation of a counter-current system between the proximal convoluted tubules and the peritubular capillaries in rat renal cortex. METHODS: In male pentothal-anesthetized Wistar rats (body weight 200-250 g), India ink was injected into the aorta above the renal arteries, followed by instant freezing of the right kidney in isopentane at -165 degrees C, and subsequent freeze-substitution in alcohol. In microscopic slides from kidneys in which only 20-55% of the cortical peritubular capillary loops was filled with ink--representing the arterial end of the capillaries--and in which the proximal tubular segmentation could be identified in PAS-stained sections, the segments of the convoluted proximal tubules were quantitatively compared with regard to the presence of ink-stained and unstained peritubular capillaries in nephrons from the whole renal cortex. RESULTS: In the microscopic specimens of the five animals used both the loops from the first segment (P1) of the proximal convoluted tubule and those of the second segment (P2) were systematically packed closely together, the transitional segment (P1-2) being interposed between the groups. Around the loops of P1, 8%+/-2% of the capillaries was stained with India ink. In contrast, surrounding the P2 loops 67%+/-5% of the capillaries contained ink, significantly exceeding that for P1 (p<0.01). CONCLUSION: Throughout the rat renal cortex, the most proximal fraction of the peritubular capillaries surrounds the second segments of the proximal convoluted tubules, while the first tubular segments are surrounded by the more distal fraction of the peritubular capillaries. Consequently, the flows in the peritubular capillaries and in the proximal convoluted tubules in the rat renal cortex are systematically arranged as a counter-current system. This feature was previously identified only in superficial nephrons.     

Die Kultur von Tuberkelbacillen aus Larynxabstrichen

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Kidney function during 12 months of strict metabolic control in insulin-dependent diabetic patients with incipient nephropathy

Thirty-six patients with insulin-dependent diabetes mellitus who had Albustix-negative urine but elevated urinary albumin excretion (30 to 300 mg per 24 hours) were matched in pairs according to their urinary albumin level, blood glycosylated hemoglobin level, and sex and assigned randomly to either unchanged conventional treatment or continuous insulin infusion. During the next 12 months a significant improvement in glycemic control was observed in the insulin-infusion group, with a reduction in the mean glycosylated hemoglobin level from 9.5 to 7.3 percent. There was no change in the control group (9.3 to 9.2 percent). No significant change in albumin excretion was observed in either group. The mean blood pressure increased slightly in both groups (from 98 to 101 mm Hg in the insulin-infusion group and from 98 to 103 mm Hg in the control group). Kidney size was significantly reduced in all patients during insulin infusion, but no consistent change was observed in the control group. No significant change was observed in the glomerular filtration rate. Our data suggest that the pathologic processes causing microalbuminuria in early renal disease are not reversed during 12 months of strict metabolic control.     

Hyperparathyroidism after neck irradiation for Hodgkin's disease

A 38-year old man developed hypercalcaemia 13 years after treatment with mantle field radiation for Hodgkin's disease. A parathyroid tumour was removed surgically. The histological diagnosis was parathyroid adenoma with marked central fibrosis. Hyperparathyroidism as a possible late complication of radiation therapy of malignant diseases has, to our knowledge, not been described before. Key words: Hodgkin's disease, hyperparathyroidism, irradiation, parathyroid adenoma.     

A case of liver cirrhosis with alpha-1-antitrypsin globules and hepatitis B surface antigen seropositivity

PAS staining, immunohistochemical examination and electron microscopy revealed presence of alpha-1-antitrypsin (AAT) globules in the hepatocytes of a HBsAg and anti-HBc seropositive female patient diseased of liver cirrhosis. The possible causes of cirrhosis are briefly analysed and the diagnostic importance of PAS-positive, amylase-resistant hepatocellular inclusions is discussed. Apart from the case reported, only two of 509 cirrhotic livers of adults, examined either by biopsy or post mortem, demonstrated similar characteristic PAS-positive globules. This indicates that in the population group (135,000 persons) referred for health care to the hospital where the examinations were done, AAT deficiency has played a negligible role in the development of liver cirrhosis in adults.     

Electrophysiological effects of dridocainide on isolated canine,guinea-pig and human cardiac tissues

The cellular electrophysiological effects of dridocainide (EGIS-3966), a novel class I antiarrhythmic agent, was studied using conventional microelectrode techniques in canine cardiac Purkinje fibres and papillary muscle preparations obtained from humans and guinea-pigs. In each preparation, dridocainide (0.6–2 mol/l) decreased the maximum velocity of action potential upstroke (V_max) in a frequency-dependent manner, although marked differences were observed in its effects in Purkinje fibre and ventricular muscle preparations. In canine Purkinje fibres, action potential duration measured at 50% and 90% of repolarization was decreased, while action potential duration measured at 10% of repolarization was increased by dridocainide. In addition, the plateau of the action potential was depressed by the drug. These changes in action potential configuration were not observed in guinea pig or human papillary muscles. The offset kinetics of the dridocainide-induced V _max block were different in Purkinje fibres and in ventricular muscle: the slow time constant of recovery of V _max was estimated to be 2.5 s in dog Purkinje fibre and 5–6 s in human and guinea-pig papillary muscle. In guinea-pig papillary muscle, the rate of onset of the V _max block was 0.15 and 0.2 per action potential in the presence of 0.6 and 2 mol/l dridocainide, respectively. Dridocainide also decreased the force of contraction in this preparation. On the basis of the present results, dridocainide appears to posess mixed class LC and LA properties, with LC predominance in human and guinea-pig ventricular muscle. Present results also indicate that results of conventional classification of class I drugs may depend on the parameters chosen, as well as on the preparation selected.     

Percutaneous drainage in the treatment of accidentally discovered hydatid cyst in patients with polycystic liver]

This article report on a not very well-known therapeutical procedure used among only fairly diagnosed cases based on international and Hungarian experiences. In Hungary echinococcus cyst of the liver is mostly treated surgically (the average mortality rate of liver resection is 0-6.3%). In many places the percutan puncture and drainage are contraindicated in case of echinococcus cysts. The authors assert that the percutaneous treatment of echinococcus cysts in proper technical and methodic circumstances in safe regarding the previous studies and their own data obtained of a few cases, and describe the technique and raise some question in them. Drainage treatment is very well tolerated by the patients it reduces the duration (of time) and the cost of the hospitalization.     

Contribution of kinases and the CD45 phosphatase to the generation of tyrosine phosphorylation patterns in the T-cell receptor complex zeta chain

The zeta subunit of the T-cell receptor complex plays a crucial role in coupling the antigen binding alphabeta and gammadelta heterodimers to the downstream activation pathways. Three tandem amino acid sequence motifs containing pairs of exactly spaced Tyr-X-X-Leu/Ile sequences, designated as Immunoreceptor Tyrosine-based Activation Motifs (ITAMs), control this function. The phosphorylated forms of ITAMs serve as docking sites for several src homology 2 (SH2) domain containing signaling proteins. The composition of the assembled signaling complex and the outcome of cell activation depends on the tyrosine phosphorylation pattern of the zeta polypeptide. The mechanism that conducts the generation of various phosphorylated forms has not yet been well established. In this study we have analyzed the ability of src family tyrosine kinases and the CD45 tyrosine phosphatase in determining the phosphorylation state of the different ITAMs and the individual tyrosine residues of the TCR zeta chain. The intracellular part of the zeta chain was phosphorylated by src family tyrosine kinases, p56lck and p59fyn in vitro. Synthetic oligopeptides representing full-length or half-sized ITAMs with a single tyrosine residue were also phosphorylated by both p56lck and p59fyn. In contrast, an additional membrane proximal tyrosine residue in the human zeta chain, located outside of the ITAMs, was not phosphorylated. We also examined the activity of the CD45 phosphatase, using a panel of ITAM derivatives, in which one or both tyrosines were phosphorylated. The efficiency of ITAM dephosphorylation by CD45 was dependent on the primary sequence of the oligopeptides and the position of the phosphotyrosine residues. The in vitro data suggest that the CD45 phosphatase rather than the tyrosine kinase(s) may control the generation of specific phosphorylation patterns of the zeta chain during cell activation.     

Single layer continuous absorbable sutures for gastrointestinal anastomosis

Authors evaluated the safety of single layer continuous sutured anastomosis technique with two different types of absorbable sutures in 252 anastomoses performed on 178 patients. In the prospective, randomized study 5 oesophagus, 26 stomach, 117 small intestine, 32 colonic, 29 pancreatic and 43 biliary anastomoses were performed. In 136 cases poliglecaprone 25 (Monocryl), in 116 cases glycomer 631 (Biosyn) were used. All procedures were carried out by the same surgeon. Anastomosis related complication was detected in 7 cases (2.8%), some kind of anastomosis insufficiency--including minor leakage--in 5 cases (2.0%), but reoperation only in one case (0.4%) was required. There was no anastomosis related death. Authors overview the advantages of the technique, which is safe, cheap, easy to carry out, physiological and least harmful to the blood supply, so they recommend its use in the gastrointestinal surgery as a standard procedure.