Active and inactive renin after exercise

Summary The effects of graded exercise on plasma concentrations of active and inactive renin were studied in seven healthy men. Exercise was performed on a cycle ergometer at four different exercise intensities (corresponding to 30%, 50%, 80% and 87% of ) for 10 min each. Concentrations of active renin and total renin after activation by trypsin were measured by direct immunoradiometric assay. Non-trypsin-activated renin concentration (inactive) was obtained by subtraction. Active renin concentrations at 30%, 50%, 80% and 87% of were 1.2, 1.9, 3.1 and 4.6 times higher than the control concentration, respectively. Similar increases in plasma renin concentration, determined by conventional enzymatic assay, were observed at every stage. In contrast, changes in inactive renin concentration were not significant at any stage. Significant increases in noradrenaline concentration were found at every exercise stage, but adrenaline, aldosterone and lactate concentrations were significantly elevated only after exercise at 50%, 80% and 87% of . The similarity between the changes in concentration of active renin and noradrenaline would suggest that sympathetic nerve activity may have been responsible either for the release of active renin or for the conversion of inactive renin to its active form in the kidney.     

Effects of endurance training on myosin heavy-chain isoforms and enzyme activity in the rat diaphragm

We investigated the effects of endurance training (20 m/min, 60 min/day, 5 days/week) on myosin heavy-chain (MHC) isoforms and succinic dehydrogenase (SDH) activity in rat crural and costal diaphragms, and plantaris muscles. Although the 4-week endurance training produced significant (P<0.05) increases, both in SDH activity and the percentage of isoform HCIIa in the plantaris of the trained rat compared with the sedentary control rat, these alterations did not occur in either the crural or costal diaphragms. After 10 weeks of endurance training, trained animals had significantly (P<0.05) higher SDH activity in the costal diaphragm and the plantaris. Moreover, a significant (P<0.05) decrease occurred in the percentage of HCIIb in the costal diaphragm, and a significant (P<0.01) decrease in the percentage of HCIIb concomitant with a significant (P<0.05) increase of HCIIa resulted in the plantaris. However, the crural diaphragm did not show any significant changes after 10 weeks of endurance training. These results indicate that endurance training induces an alteration in the expression of an MHC phenotype, in addition to causing an increase in oxidative enzyme activity. However, the alterations in response to endurance training are apparently not uniform, varying between regions and/or kinds of muscles.     

The effects of buffer ingestion on metabolic factors related to distance running performance

We examined the effects of sodium bicarbonate (BIC) and sodium citrate (CIT) ingestion on distance running performance. Seven male runners [mean = 61.7 (SEM 1.7) ml · kg^–1 · min^–1] performed three 30-min treadmill runs at the lactate threshold (LT) each followed by a run to exhaustion at 110% of LT. The runs were double-blind and randomly assigned from BIC (0.3 g · kg body mass^–1), CIT (0.5 g · kg body mass^–1) and placebo (PLC, wheat flour, 0.5 g · kg body mass^–1). Venous blood samples were collected at 5, 15 and 25 min during the run and immediately post-exhaustion (POST-EX) and analysed for pH, and the concentrations of lactate ([1a^–]_b) and bicarbonate ([HCO₃ ^– ]). Performance was measured as running time to exhaustion at 110% of LT (TIME-EX). The pH was significantly higher (P 0.05) for the BIC and CIT trials during exercise, but not POST-EX compared to PLC. The [1a^–]_b was significantly higher (P 0.05) for the CIT trial compared to PLC during exercise, and for both CIT and BIC compared to PLC at POST-EX. Blood [HCO₃ ^–] was significantly higher (P 0.05) during exercise for BIC compared to PLC. TIME-EX was not significantly different among treatments: BIC 287 (SEM 47.4) s; CIT 172.8 (SEM 29.7) s; and PLC 222.3 (SEM 39.7) s. Despite the fact that buffer ingestion produced favourable metabolic conditions during 30 min of high intensity steady-state exercise, a significant improvement in the subsequent maximal exercise run to exhaustion did not occur.     

Localization,structure and polymorphism of two paralogous <Emphasis Type="Italic">Xenopus laevis</Emphasis> mitochondrial malate dehydrogenase genes

Two paralogous mitochondrial malate dehydrogenase 2 (Mdh2) genes of Xenopus laevis have been cloned and sequenced, revealing 95% identity. Fluorescence in-situ hybridization (FISH) combined with tyramide amplification discriminates both genes; Mdh2a was localized into chromosome q3 and Mdh2b into chromosome q8. One kb cDNA probes detect both genes with 85% accuracy. The remaining signals were on the paralogous counterpart. Introns interrupt coding sequences at the same nucleotide as defined for mouse. Restriction polymorphism has been detected in the first intron of Mdh2a, while the individual variability in intron 6 of Mdh2b gene is represented by an insertion of incomplete retrotransposon L1Xl. Rates of nucleotide substitutions indicate that both genes are under similar evolutionary constraints. X. laevis Mdh2 genes can be used as markers for physical mapping and linkage analysis.     

Effects of glucose in protected ischemic kidneys

Summary Energy reserves (TAN) and anaerobic substrates (glucose, glycogen) are lower in renal than in myocardial tissue. Euro-Collins-solution contains nearly 200 mmol/l glucose, while the HTK-solution of Bretschneider contains none. Therefore the influence of glucose on kidney lactate production, on energy reserves (TAN), intrarenal pH and on morphology during the protection of ischemic kidneys was analysed using either Euro-Collins-solution, or modified Euro-Collins-solution, containing mannitol instead of glucose, or HTK-solution with and without the addition of 5, 10 and 20 mmol/l glucose. Glucose content changed during kidney perfusion with Euro-Collins-solution from about 60 to 800 mol/g_dw. While intrarenal pH decreased from 7.1 to 5.1 in Euro-Collins-kidneys during 420 min of ischemia at 25°C, pH decreased to 6.7 with the modified, mannitol containing Euro-Collins-solution. In HTK-protected kidneys intrarenal pH decreased with increasing glucose addition to the solution. Although Total Adenine Nucleotides are highest at the end of ischemia with Euro-Collins-solution, structural protection after the same ischemic stress was best in HTK-protected kidneys without glucose addition. We conclude that glucose stimulated lactate production, reduced interstitial pH in the kidney even in combination with a highly buffered solution and that it might cause greater membrane permeability leading to a structural detoriation. Mannitol seemed more appropriate than glucose in this respect, although other substances, which provide energy substrate and prevent structural damage, may exist.Supported by the Deutsche Forschungsgemeinschaft, SFB 89 —Kardiologie Göttingen     

Effect of vibration on red cell metabolism

Summary In investigating the influence of vibrational energy on the metabolism of the erythrocyte, it was hypothesized that under conditions of normal PaO₂ and SaO₂ in arterial blood, vibration induced vasoconstriction would decrease local blood flow and induce hypokinetic hypoxia. This decreased blood flow and therefore decreased delivery of oxygen to the tissue would markedly lower tissue PO₂ (hypokinetic hypoxia), which would influence the energetics and metabolism of the erythrocyte. The metabolism of the red blood cell (RBC) was evaluated by measuring the enzymatic activities of PFK (2.7.1.11), PGI (5.3.1.9), PK (2.7.1.40), and aldolase (4.1.3.13) from the anaerobic glycolytic cycle and D-G-6-P (1.1.1.49) from the pentose cycle. Also measured were the levels of ATP and 2,3 DPG and the in-vitro production of lactic acid. In the group of workers showing early changes (vibration angioneurosis) associated with the vibration syndrome, changes in RBC metabolism were demonstrated. Statistically significant were increases of PFK, PK and the production of lactic acid, indicating the activation of anaerobic glycolysis. Furthermore statistically significant were the increased 2,3 DPG and decreased ATP levels.     

改良琼脂糖凝胶电泳法测定血清LDH同工酶的应用

目的 寻求更加准确、简便、快速、实用的乳酸脱氢酶同工酶（LDH）测定方法。方法 据LDH同工酶等电点不同,选择琼脂糖胶作支持物,对以往LDH同工酶测定方法进行改进,将五型LDH同工酶进行分离并定量测定。结果 改进后的LDH同工酶测定方法稳定,区带清晰,重复性好,结果可靠,试剂可长期保存。结论 改良琼脂糖凝胶电泳法测定血清LDH同工酶应用前景良好。     

G3PD的修饰蛋白对急性肾功能衰竭大鼠丙二醛和超氧化物岐化酶的影响

目的：研究3－磷酸甘油醛脱氢酶的修饰蛋白（modifier protein,MP）对急性肾功能衰竭（acute renal failure,ARF）大鼠丙二醛（malondialdehyde,MDA）和超氧化物岐化酶（superxide dismutase,SOD）的影响。方法：利用庆大霉素致ARF的动物模型,将大鼠随机分成4组：正常对照组、阴性对照组、阳性对照组和实验组,采用硫代巴比妥酸法和羟胺法分别测定血清及肾皮质匀浆MDA和SOD,光镜、电镜观察肾组织学改变,同时测定血肌酐（Scr）。结果：实验组、阳性对照组血清及肾皮质匀浆MDA明显下降,SOD明显上升,P＜0．01。同时Sct下降。光镜、电镜示实验组、阳性对照组肾脏病理仅呈灶状改变。比阴性对照组减轻。结论：MP可以缓解氧自由基损伤,减轻ARF时的肾脏病理改变,改善肾功能。     

Towards a new WHO classification of renal cell tumor: what the clinician needs to know—a narrative review

In 1952, renal cell carcinomas had been divided into 2 categories—clear cell or granular cell—depending upon their cytoplasmic staining characteristics. In the following years, the inventory of renal epithelial tumors has expanded by the addition of tumors named by their architectural pattern (i.e., papillary RCC, tubulocystic RCC), anatomic location (i.e., collecting duct carcinoma, renal medullary carcinoma), associated diseases (i.e., acquired cystic disease-associated RCCs). With the extensive application of molecular diagnostic techniques, it becomes possible to detect genetic distinctions between various types of renal neoplasm and discover new entities, otherwise misdiagnosed or diagnosed as unclassified RCC. Some tumors such as ALK rearrangement-associated RCC, MiT family translocation renal carcinomas, SDH-deficient renal cancer or FH-deficient RCC, are defined by their molecular characteristics. The most recent World Health Organization (WHO) classification of renal neoplasms account for more than 50 entities and provisional entities. New entities might be included in the upcoming WHO classification. The aim of this review is to summarise and discuss the newly acquired data and evidence on the clinical, pathological, molecular features and on the prognosis of new RCC entities, which will hopefully increase the awareness and the acceptance of these entities among clinicians and improve prognostication for individual patients.