The mechanisms of fast renal compensation

Summary The changes in blood concentration which result in the adjustment of excretion when renal functioning mass is acutely reduced have been investigated by means of paired experiments on isolated dog kidneys. One kidney was perfused with undiluted blood; the other kidney was perfused with blood supplemented with an amount of water and solutes corresponding to the amount retained after the suppression of the contralateral kidney in situ; the response was evaluated from the difference in excretion between the two organs. The results may be summarized as follows: a) the adjustment of the excretion of water, sodium, potassium and urea results from small changes in blood concentration (haematocrit, plasma proteins and solutes), in the absence of specific stimuli of extrarenal origin; b) increased urea concentration is not the major determinant of the readjustment of sodium and water excretion; c) the response is potentiated by high arterial blood pressure; d) if the load of water exceeds the load of sodium, this ion is retained by the kidney even in the presence of an osmotic load of urea; e) the changes in the blood concentrations do not provide an adequate adjustment of the excretion of phosphate; f) increased excretion per nephron results from decreased fractional reabsorption without significant change in glomerular filtration rate.     

Intrauterine insemination treatment in subfertility: an analysis of factors affecting outcome

A total of 811 intrauterine insemination (IUI) cycles in which clomiphene citrate/human menopausal gonadotrophin (HMG) was used for ovarian stimulation were analysed retrospectively to identify prognostic factors regarding treatment outcome. The overall pregnancy rate was 12.6% per cycle, the multiple pregnancy rate 13.7%, and the miscarriage rate 23.5%. Logistic regression analysis revealed five predictive variables as regards pregnancy: number of the treatment cycle (P = 0.009), duration of infertility (P = 0.017), age (P = 0.028), number of follicles (P = 0.031) and infertility aetiology (P = 0.045). The odds ratios for age < 40 years, unexplained infertility aetiology (versus endometriosis) and duration of infertility < or = 6 years were 3.24, 2.79 and 2.33, respectively. A multifollicular ovarian response to clomiphene citrate/HMG resulted in better treatment success than a monofollicular response, and 97% of the pregnancies were obtained in the first four treatment cycles. The results indicate that clomiphene citrate/HMG/IUI is a useful and cost-effective treatment option in women < 40 years of age with infertility duration < or = 6 years, who do not suffer from endometriosis.     

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.     

Multiplicity of allergens in peanuts

Crude peanut protein fractions from raw and roasted peanuts were examined in the RAST with 10 sera from patients showing clinical peanut sensitivity. The radioactive uptake results, which were generally high, did not reveal any distinguishable pattern. Two commercially available peanut proteins, peanut lectin and phospholipase D, gave poor RAST responses. Three purified peanut proteins, α-arachin, conarachin I, and concanavalin A-reactive glycoprotein, all gave significant RAST results that were generally lower than those obtained with the crude extracts. The extent of RAST inhibition obtained with these materials was inversely related to their abundance in the total peanut protein. Crossed immunoelectrophoresis with extracts from raw and roasted peanut indicated the presence of 22 and 10 anodically migrating antigens, respectively. Sixteen IgE binding antigens were revealed for raw peanut and seven for roasted peanut after incubation with a mixed serum from the 10 patients in crossed radioimmunoelectrophoresis (CRIE) using ¹²⁵I-labeled anti-IgE. CRIE plates treated with individual serum samples showed that all the patients had specific IgE for the major antigen peak, which has been tentatively identified as α-arachin. This major storage protein of peanut, which is known to be particularly heat resistant, may be of greater clinical significance than its apparently low RAST activity would seem to indicate.     

Are the blood pressure and endocrine responses of healthy subjects exposed to cold stress altered by an acutely increased sodium intake?

In the study reported here, we examined blood pressure and endocrine responses in cold conditions during salt load in young healthy subjects who had previously shown increased resting blood pressure during acutely increased sodium intake. Subjects (n=53) added 121 mmol sodium into their normal diet for 1 week. If their mean arterial pressure had increased by a minimum of 5 mmHg compared to the previous measure they were selected for subsequent experiments. The subjects (n=8) were given 121 mmol supplemental sodium · day⁻¹ for 14 days. They were then put into a wind tunnel for 15 min (temperature −15 °C, wind speed 3.5 · ms⁻¹). Their blood pressure increased (P < 0.05) during the cold exposure, independent of the sodium intake. Their mean (SEM) plasma noradrenaline increased from 3.58 (0.62) nmol · l⁻¹ to 5.61 (0.79) nmol · l⁻¹ (P < 0.05) when the subjects were given a normal diet, and from 2.45 (0.57) nmol · l⁻¹ to 5.06 (0.56) nmol · l⁻¹ (P < 0.05) when the subjects were given an elevated sodium diet. The starting concentrations and the endpoint concentrations were statistically similar. The plasma levels of the N-terminal fragment of pro-atrial natriuretic peptide decreased during the whole-body cold exposure: with the sodium load the change was from 256.6 (25.5) nmol · l⁻¹ to 208.0 (25.3) nmol · l⁻¹, and with the normal diet, from 205.8 (16.4) nmol · l⁻¹ to 175.1 (16.1) nmol · l⁻¹. The haematocrit and red blood cell count increased (P < 0.05) with normal and elevated sodium diet in cold conditions, but haemoglobin increased (P < 0.05) only with high salt in cold conditions. To conclude, acutely increased sodium intake does not change the blood pressure response or hormonal responses to exposure to acute cold stress in healthy subjects. Accepted: 28 September 2000     

Venodilator effects of adenosine triphosphate and sodium nitroprusside; Comparisons during controlled hypotension

Adenosine triphosphate as well as sodium nitroprusside has been used for hypotensive anesthesia. The purpose of this study was to examine the possibility that two hypotensive drugs may exert different effects on venous capacitance during controlled hypotension. In rats anesthetized with ketamine, mean arterial pressure was lowered to 50mmHg by intravenous infusion of adenosine triphosphate or sodium nitroprusside. Venous capacitance was assessed before and during induced hypotension by measuring the mean circulatory filling pressure (MCFP). MCFP was measured after briefly arresting the circulation by inflating an indwelling balloon in the right atrium. MCFP was lower during adenosine triphosphate-induced as well as sodium nitroprusside-induced hypotension as compared with the respective value at control (P < 0.01 for adenosine triphosphate and sodium nitroprusside). However, the decrease in MCFP by adenosine triphosphate (0.8 ± 0.1mmHg) was less (P < 0.01) than that by sodium nitroprusside (2.3 ± 0.3mmHg). These results suggest that at a comparable level of arterial hypotension venodilator effect of adenosine triphosphate was less than that of sodium nitroprusside. Less venodilatation during adenosine triphosphate-induced hypotension may contribute to the maintenance of cardiac output during hypotensive anesthesia.(Hoka S, Takeshita A, Aishima K et al.: Venodilator effects of adenosine triphosphate and sodium nitroprusside; comparisons during controlled hypotension. J Anesth 1: 144–147, 1987)     

Sodium regulation of agonist and antagonist binding to β-adrenoceptors in intact and Ns-deficient membranes

Summary Agonist binding to various hormone receptors mediating adenylate cyclase inhibition is decreased by sodium ions. We studied the influence of Na⁺ on agonist and antagonist binding to -adrenoceptors in membrane preparations of guinea pig lung, S49 lymphoma wild-type cells (WT) and their N_s-deficient cyc^– variants by measuring binding of the antagonist, [¹²⁵I]iodocyanopindolol ([¹²⁵I]CYP). At 37° C, sodium decreased the receptor affinity for the agonist, isoproterenol, in all three membrane preparations. In lung and WT membranes, Na⁺ steepened the shallow agonist competition curves in a manner similar to and synergistic with guanine nucleotides. When binding was performend at 4° C, sodium regulation but not guanine nucleotide regulation of agonist binding was preserved. At the low temperature, [¹²⁵I]CYP affinity was reduced, and sodium increased [¹²⁵I]CYP binding in both N_s-containing and N_s-deficient membranes by increasing the antagonist affinity without significant change in total receptor number. Compared to Na⁺, Li⁺ and K⁺ were much less potent and efficient in decreasing agonist and increasing antagonist binding. Na⁺ and Mg²⁺ had opposite effects on agonist binding in the N_s-containing lung and WT membranes but not in the N_s-deficient cyc^– membranes. The data indicate that sodium not only regulates binding of inhibitory hormone receptors but also agonist and antagonist binding to the adenylate cyclase stimulatory -adrenoceptor. The finding that sodium regulation of -adrenoceptor binding is also observed in the N_{s 2} cyc^– membranes, furthermore, indicates that the target of sodium is not the -subunit of N_s but possibly a component common to both types of receptor systems regulating adenylate cyclase activity.     

Effects of sodium and GTP on the binding kinetics of [3H]diprenorphine in NG 108-15 cell membranes

Summary Equilibrium binding isotherms of [³H]diprenorphine in membranes from NG 108-15 cells are consistent with a homogenous population of binding sites. Upon addition of Na⁺, Mg²⁺ and GTP, only a 2-fold reduction in affinity with a minor decrease in the number of sites is observed. Dissociation curves of [³H]diprenorphine, however, are clearly biphasic: in the absence of Na⁺, Mg²⁺ and GTP, 80% of the bound ligand dissociates slowly with at _1/2 of 100 min, and only 20% rapidly (t _1/2 4.5 min). In the presence of Mg²⁺, nearly all the binding is found in the slowly dissociating form. Upon the addition of either Na⁺ or GTP, 20–30% of the binding dissociates more rapidly. The rate constant of the rapidly dissociating form generated by Na⁺, however, is 2.5 times greater than that induced by the presence of GTP. Thus, the addition of both, Na⁺ and GTP, converts about 80% of the receptor into a very fast dissociating form (t _1/2 1.7 min).Exposure of intact cells to pertussis toxin (10 ng/ml) or treatment of membranes with N-ethyl maleimide (500 M), strongly reduces the proportion of the slowly dissociating component. Following these treatments, the effect of GTP is reduced or abolished, but that of Na⁺ remains unaffected.We conclude from these data that the effects of Na⁺ and GTP are not only distinct in site but also in mechanism of action and that there are three forms of opioid receptors that can be differentiated by their kinetic properties. The slowly dissociating receptor form requires a functional N unit.     

急诊经皮冠状动脉介入手术冠脉内应用硝普钠与替罗非班治疗老年急性心肌梗死效果及影响因素分析

目的探讨急诊经皮冠状动脉介入手术(Percutaneous Coronary Intervention,PCI)冠脉内应用硝普钠与替罗非班治疗老年急性心肌梗死效果及影响因素分析。方法收集153例急性心肌梗死老年患者,进行急诊PCI冠脉内应用硝普钠与替罗非班治疗(实验组)76例和急诊PCI冠脉内应用硝酸甘油与替罗非班治疗组(对照组)77例。追踪测评患者血清肌钙蛋白Ⅰ(Cardiac TroponinⅠ,cTnⅠ)、谷胱甘肽过氧化物酶(Glutathione,GSH)、超氧化物歧化酶(Superoxide Dismutase,SOD)、N末端B型钠尿肽前体(N-terminalpro-B-typenatriureticpeptide,NT-proBNP)、白介素-6(Interleukin-6,IL-6)、肿瘤坏死因子-α(Tumor Necrosis Factor-α,TNF-α)、内皮素(Endothelin,ET)、一氧化氮(NO)、血栓素B_2(Thromboxane B_2,TXB_2)、6酮-前列腺素F1α(6-keto-prostaglandin F1 alpha,6-keto-PGF1α)以及左心室射血分数(Left Ventricular Ejection Fraction,LVEF)、心肌梗死溶栓试验血流分级(Thrombolysis In Myocardial Infarction,TIMI分级)、心功能改善效果。结果实验组c TnⅠ、GSH、SOD、NT-pro BNP、IL-6、TNF-α、ET、NO、TXB_2、6-keto-PGF1α、LVEF、心功能改善效果、TIMI的追踪组间得分及复测组间得分差异有统计学意义(F=23.129、24.742、25.510、26.048、26.444、25.371、28.320、22.322、25.317、26.372、24.314、24.512、22.147,均P<0.05)。结论急诊PCI冠脉内应用硝普钠与替罗非班治疗老年急性心肌梗死患者对于心功能改善效果显著提高,并其受年龄、身体质量指数(Body Mass Index,BMI)、并发症、病变血管数量以及干预前心功能等级的影响。     

透明质酸钠关节内注射治疗膝骨性关节炎

目的　观察透明质酸钠注射液对膝骨关节炎的疗效。方法　关节内注射透明质酸钠 2ml,每周一次 ,5周一疗程 ,疗程结束后连续随诊一年半以上。结果　疗程结束时总有效率为 92 7% ,随访过程 82 %患者无疼痛、肿胀、渗出等症状复发。结论　透明质酸钠可有效地抑制膝骨关节炎患者的肿胀、渗出、疼痛等症状