Effect of electrode temperature on orthostatic changes in forefoot transcutaneous oxygen tension (tc-PO2)

The influence of increasing the temperature of the transcutaneous oxygen tension (tc-PO2) electrode from 37 to 45 degrees C on the orthostatic changes in tc-PO2 was studied in six normal subjects. The tc-PO2 electrode was mounted on the forefoot. The blood pressure of the forefoot was changed by elevating and lowering the forefoot in relation to heart level. At all electrode temperatures tc-PO2 decreased about 35% when the forefoot was elevated. At electrode temperatures between 41 and 45 degrees C tc-PO2 increased about 20% when the electrode was lowered below heart level. This indicates a passive vascular bed in the heated tissue under the electrode. However, at 37 degrees C tc-PO2 decreased about 40% when the forefoot was lowered. This indicates that the local vasoconstrictor response to increased venous transmural pressure is preserved when the tissue under the electrode is heated to 37 degrees C only. The study suggest that tc-PO2 monitoring at 37 degrees C may be used for continuous, non-invasive monitoring of the local vasoconstrictor response, and thus of arteriolar contractility and intact sympathetic innervation.     

低温透析对透析中低血压患者左心室功能的影响

目的探讨低温透析对维持性血液透析患者左心室功能（left ventricular function,LVF）的影响。方法选取在解放军117医院肾脏病中心充分透析6月以上,近1月有反复透析中低血压发作史的患者20例,随机分为A组与B组,透析温度分别设定为37℃和35℃。所有患者每次透析前、透析结束时和透析结束后30min接受超声心动图检查,连续监测血压等血流动力学指标,并以量表记录患者与低温相关的主观感受。每两周一次监测患者透析前后生化指标和血常规。每两周两组患者交换治疗模式一次,共观察8周。结果①37℃或是35℃透析对维持性血液透析患者的血红蛋白、电解质、血浆白蛋白、C-反应蛋白、肌钙蛋白-T、甲状旁腺素、Kt/Vurea无明显影响;②低温透析阶段比常温透析阶段平均动脉压显著升高（P〈0.001）,心率显著降低（P〈0.001）;③低温透析阶段症状性透析中低血压（intradialytic hypotension,IDH）（P〈0.001）和无症状性IDH（P〈0.001）发生率显著都降低;④低温透析后左室短轴缩短分数（SF）（P〈0.001）和射血分数（EF）（P〈0.001）均显著高于常温透析后;⑤低温透析时节段性室壁运动异常（regional wall motion abnormality,RWMA）发生明显少于常温透析时（P〈0.001）,透析后RWMA恢复比例亦高于常温透析时（P〈0.001）;⑥低温透析使患者寒冷感受与常温透析时相比无统计学意义（P〉0.05）。结论低温透析可明显改善透析中低血压患者左心室功能,减少透析中RWMA和透析中低血压的发生,患者寒冷不适无明显增加。     

Effect of temperature on protein binding of cortisol

OBJECTIVES: Biological effects of cortisol are substantially determined by protein binding of the hormone. The aim of our study was to characterize temperature effects on cortisol protein binding by use of an equilibrium dialysis method. DESIGN AND METHODS: Serum samples obtained from ten healthy volunteers were submitted to equilibrium dialysis. Each sample from the individuals was incubated for 16 h at 37 degrees C, 38 degrees C, 39 degrees C, 40 degrees C and 41 degrees C, respectively. In the dialysate samples obtained, cortisol concentrations were measured by immunoassay. RESULTS: For samples incubated at 37 degrees C, a mean dialysate cortisol concentration of 0.41 microg/dL (SD=0.14) was found. Gradual increase of dialysate cortisol concentration was observed with increasing incubation temperatures. For samples incubated at 41 degrees C, a mean dialysate cortisol of 0.75 microg/dL (SD=0.24) was found. Thus, the mean percentage of free-to-total cortisol increased by about 80% from 3.7% (SD=1.1) at 37 degrees C to 6.7% (SD=1.8) at 41 degrees C. CONCLUSIONS: The results of our in vitro experiments suggest that during fever the free-to-total ratio of cortisol is increased substantially compared to normal conditions, and that administration of antipyretic drugs might potentially be associated with substantial changes in the bioavailability of cortisol.     

Bradykinin-associated reactions in white cell-reduction filter

PURPOSE: The purpose of this study was to examine the effect of temperature on bradykinin generation during blood transfusion using positively charged (positive filter), negatively charged (negative filter), and neutral (neutral filter) filters. MATERIALS AND METHODS: Whole blood collected from six volunteers at 4 degrees C or 37 degrees C was passed through the positive or negative filter. In six surgical patients during surgery, autologous blood transfusion at 37 degrees C was initiated through the positive filter, and the same transfusion was reintroduced through the negative filter. Whole blood from another six volunteers at 4 degrees or 37 degrees C was passed through the neutral filter. RESULTS: The positive filter did not generate bradykinin at any temperature, whereas the negative filter generated bradykinin by approximately 4,000-fold when warm blood was used but did not at cool blood. Blood pressure decreased and heart rate increased during warm blood transfusion using the negative filter but did not change using the positive filter. Plasma bradykinin levels increased in patients with use of the negative filter. The neutral filter generated bradykinin when warm blood was used but at levels lower than for the negative filter. CONCLUSIONS: Use of negative filter results in the temperature-dependent generation of bradykinin, which becomes a potential anaphylatoxin when warm blood is used.     

苯磺酸氨氯地平联合贝那普利对腹膜透析患者血压及血压变异性的影响

目的 观察苯磺酸氨氯地平联合贝那普利对腹膜透析患者血压及血压变异性的影响.方法 将165例高血压肾病或肾性高血压腹膜透析患者经过 2 周安慰剂导入期筛选出145例随机分为2组,治疗组80例:给予苯磺酸氨氯地平和贝那普利口服;对照组65例,对照组给予硝苯地平缓释片和贝那普利口服,治疗1月后随访血压24月,每1月随访1次,观察2组治疗前后血压、血压变异性的差异及心血管事件发生情况,包括心力衰竭(根据临床表现判断级NYHAⅡ 以上),急性冠脉综合征(不稳定性心绞痛、急性心肌梗死、心源性猝死).结果 2组治疗前后血压及血压变异性比治疗前明显下降(P ＜0.01),治疗组血压变异性降低幅度比对照组降低幅度大( P＜0.01),两组间血压降低幅度没有显著性差异(P ＞0.05),治疗后治疗组心血管事件发生率低于对照组( P＜0.01),心血管事件死亡率亦低于对照组(P ＜0.01).结论 治疗组和对照组都能有效的控制腹膜透析患者的血压,但治疗组能有效的降低腹膜透析患者的血压变异性,从而降低腹膜透析患者心血管事件发生率及心血管事件死亡率.     

An acute hemolytic transfusion reaction caused by an anti-P1 that reacted at 37 degrees C

BACKGROUND: Hemolytic transfusion reactions (HTRs) due to anti-P1 have rarely been reported. There is only one report (from 1945) of an acute HTR due to anti-P1. CASE REPORT: A 74-year-old woman with anti-P1 was given blood that had been found to be compatible by the use of prewarmed serum and saline-suspended red cells (RBCs) and of an antiglobulin test with anti-IgG. The test mixtures were not centrifuged or inspected for agglutination after the 37 degrees C incubation phase. After transfusion of 50 mL of P1 + blood, the patient had an acute HTR (hemoglobinemia, hemoglobinuria, and increased blood pressure, temperature, and respiration). RESULTS: When studied by a reference laboratory, the anti-P1 was shown to be easily detectable (3+ agglutination) by a prewarming technique (saline or low-ionic-strength saline [LISS]), which included centrifugation at 37 degrees C, but only weak reactions were observed when centrifugation after 37 degrees C incubation was omitted. The indirect antiglobulin test was weakly positive (1+) with anti-IgG, but polyspecific anti-human globulin reacted 2+. The anti-P1 agglutinin was IgM, and its titer was 16 at 37 degrees C (prewarmed) and 256 at 23 degrees C; it caused hemolysis of RBCs at 37 degrees C under conditions known to enhance hemolysis. An indirect monocyte monolayer assay gave results of 11.2 and 22 percent in testing of P1 + RBCs incubated with the patient's serum alone and with patient's serum plus fresh normal serum (as a source of complement), respectively (normal < or = 3%). CONCLUSION: An acute HTR was caused by a hemolytic anti-P1 that reacted at 37 degrees C. This antibody was not detected by the hospital in a prewarmed crossmatch that omitted 1) the addition of LISS, 2) the reading for agglutination after the 37 degrees C incubation, and 3) the use of antiglobulin sera containing anti-complement.     

透析用水的细菌培养方法比较

目的比较几种透析用水细菌培养方法的敏感性,寻找其中方便、快速、敏感性高的方法。方法在北京市某三甲医院血透中心随机采样透析用水共85份,分别用4种方法进行细菌培养:①哥伦比亚血琼脂平板培养基37癈培养48h、②TSA培养基37癈培养48h、③R2A培养基37癈培养48h或④20癈培养7d,同时设立阳性及阴性对照组。结果 1.R2A培养基20癈培养7d细菌检出率最高;37癈培养48h细菌检出率降低,但均高于TSA培养基和血琼脂平板培养基。2.EBPG标准方法与选用R2A培养基37癈培养48h的方法具有较好的一致性,可以互相替代。结论我们建议采用EBPG建议的透析用水细菌培养方法,或者通过适当提高温度、缩短时间来改进EBPG建议的方法从而更方便临床使用。     

Cardioplegia flow dynamics in an in vitro model.

The flow of fluids in extracorporeal circuits does not conform to conventional Poiseuille mechanics which confounds calculating cardioplegia (CP) flow distribution. The purpose of this study was to quantify CP flow dynamics in a model simulating coronary atherosclerosis across varying sized restrictions. An in vitro preparation was designed to assess hydraulic fluid movement across paired restrictions of 51, 81 and 98% lumen reductions. Volume data were obtained at variable flow, temperature, viscosity and pressure conditions. CP delivered through 14- and 18-gauge (GA) conduits at 8 degrees C and 100 mmHg infusion pressure revealed that both four to one and crystalloid CP solutions had significantly less total percentage flow through the 14-GA conduit, p < 0.0001 and p < 0.001, respectively. Overall, 4:1 CP exhibited the most favorable fluid dynamics at 8 degrees C in that it delivered the highest percentages of total CP flow through the smaller lumen conduit. At both 8 degrees C and 37 degrees C delivery, blood CP resulted in the least homogeneous fluid distribution at all delivery parameters. The results in relation to blood viscosity indicate that, although the 8 degrees C blood CP had a significantly greater viscosity than 37 degrees C blood CP, it did not produce an effect in fluid distribution. These data show that increasing the cardioplegic solution hematocrit causes an inhomogeneous fluid distribution regardless of delivery temperature or infusion pressure.     

低温透析对维持性血液透析患者生活质量的影响

目的 探讨低温透析对维持性血液透析患者生活质量的影响。方法 选择2008年1月至2010年6月在血液透析（HD）中心透析中经常出现低血压的患者20例为研究对象,采用自身前后对照的方法,分别接受3种不同的透析温度（37?C、35.5?C、35?C）各2个月,同时每月进行健康状况调查问卷SF-36量表评估。并观察其透析过程低血压发生的频率,以及治疗前后血压、血清白蛋白和透析充分性的变化。结果 患者给予低温透析后,SF-36量表评分明显增加,包括生理功能、躯体疼痛、总体健康、活力、社会功能;低血压发生率减低（P<0.01）,血红蛋白水平升高（P<0.01）。结论 低温透析有利于预防血液透析患者低血压的发生,能改善患者生活质量。     

A Study of the Efficacy and Safety of Moexipril in Mild to Moderate Hypertension

This placebo-controlled, double-blind, multicenter study examined the efficacy, safety, and tolerability of the angiotensin-converting enzyme inhibitor, moexipril, in lowering blood pressure in mildly to moderately hypertensive patients. Patients were initially randomized into four groups, two of which received moexipril 7.5 mg per day and two received moexipril 15 mg per day, for first 12 weeks of treatment. Patients then entered a withdrawal phase with one of the groups in each dose category continuing that dose of moexipril and one receiving placebo for 12 more weeks. From 223 patients randomized initially, 190 completed the 12-week withdrawal phase. In the two dosage groups from baseline to 12 weeks, sitting diastolic blood pressure decreased from 101.1 to 92.8 mm Hg for the 7.5-mg group and from 100.7 to 91.3 mm Hg for the 15-mg group (p < 0.05 baseline to week 12 in both groups) with a significant difference between those groups attained at week 12 only (p = 0.03). By the end of the withdrawal phase (24-week evaluation), the group that continued to receive 7.5 mg moexipril decreased diastolic blood pressure by 8.2 mm Hg, whereas the corresponding placebo group decreased diastolic blood pressure by 3.7 mm Hg. Although the difference between these two groups was not significant at the 24-week end point, all other time points differed significantly between groups at p less-than-or-equal 0.017. Similarly, whereas the corresponding placebo group had a mean reduction in diastolic blood pressure of 4.6 mm Hg, the group that continued 15 mg of moexipril showed a mean diastolic blood pressure reduction of 10.6 mm Hg (p < 0.001 between groups). No comparison between the two moexipril dosage groups was significant, however, during the withdrawal phase. These results during medication withdrawal indicate that moexipril is effective in significantly lowering diastolic blood pressure.     

B型全血加入不同剂量O型全血后游离血红蛋白变化

为了解B型全血加入不同剂量O型全血后在37℃与室温条件下游离血红蛋白的变化,随机抽取4℃保存24小时B型全血两人份,分别分装为60 ml,按不同比例加入O型全血9、12、15、18 ml置入100ml塑料血袋内混匀后,分别放置在37℃孵箱和室温条件下,间隔15分钟摇动1次.分别在1、2、4、8和12小时留取标本做游离血红蛋白检查.结果表明B型全血加入不同剂量O型全血,在12小时内游离血红蛋白量的变化无显著性差异.随着保存时间的延长不管是室温还是37℃条件下,1 小时以后均有显著性差异,一袋B型全血在室温与37℃条件下放置1-8小时无明显差别(P＞0.05),到12小时P＜0.001.另一袋在室温与37℃条件下放置1小时P＞0.05,2-8小时P＜0.001,有明显差别.结论在B型全血中加入O型全血,放置12小时不会引起游离血红蛋白升高.在室温与37℃存放8小时后接近和超过存放2天的水平170.4 mg/L,这提示血液采集后应尽快置入2-4℃冷藏,减少红细胞的分解代谢、衰老裂解而释放更多的FHb及其它代谢物质对机体的损害.     

Haemodynamic response to moderate thermal stress in pregnancy

The effect of a moderate heat stress on cardiovascular responses was studied: group I consisted of 15 healthy non-pregnant women, group II of 23 women 13-14 weeks pregnant and group III of 23 women 36-37 weeks pregnant. Heart rate, stroke volume, cardiac output, arterial blood pressure and peripheral vascular resistance were recorded every 5-10 minutes during a resting period (20 min, 21-23 degrees C) followed by heat stress (20 min, 70 degrees C, 15% relative humidity) and a recovery period (45 min, 21--23 degrees C). The rectal temperature increased 0.3-0.4 degrees C in each group during thermal stress. The heart rate before stress was highest in the advanced pregnancy group but increased almost identically in each group by 36--37 beats per minute during stress and approached starting values during recovery. There were no major changes in stroke volume during the experiment in any group nor were there any differences between the three groups. Arterial blood pressure did not change significantly in any group during the experiment; the differences between the groups were minimal. Peripheral vascular resistance began to fall at the start of the thermal stress and returned to prestress levels at the end of the recovery period. There were no differences between the groups in proportional changes of peripheral resistance. We conclude that pregnancy does not alter the cardiovascular responses to moderate thermal stress.     

Evaluating the dynamic performance of a fibre optic pressure microsensor

The dynamic performance of a new fibre optic sensor intended for measuring physiological fluid pressures is assessed in water. The sensor's sensitivity is evaluated at 23 degrees, 35 degrees and 37 degrees C against a Millar pressure catheter for sinusoidal pressure inputs with frequency ranging from 0.5 to 10 Hz. We found that sensitivity versus frequency is flat to 6 Hz and decreases slightly between 6 and 10 Hz. The sensitivity is slightly lower at 23 degrees C than at 37 degrees C. The reproducibility of measurements is excellent (two separate calibration tests in two consecutive days). The output of the fibre optic system used shows a constant time delay (0.13 s) for all frequencies tested. Experiments suggest that, with current sensor design, its immersion in degassed water prior to use ensures a reliable performance.     

Gene expression control by temperature with thermo-responsive polymeric gene carriers.

A thermo-responsive copolymer, poly(N-isopropylacrylamide (IPAAm)-co-2-(dimethylamino)ethyl methacrylate (DMAEMA)-co-butylmethacrylate (BMA)), was synthesized and its in vitro gene transfection efficiency at different incubation temperatures was evaluated. A copolymer containing 8 mol% DMAEMA and 11 mol% BMA (P(IP-8DA-11BM)) had a lower critical solution temperature (LCST) at 21 degrees C, therefore the copolymer was insoluble above 21 degrees C and soluble below 21 degrees C. The LCST of P(IP-8DA-11BM) solution was not affected by the presence of salmon DNA. This copolymer was complexed with plasmid DNA, and the stability of the complex was analyzed by gel electrophoresis. DNA was completely retained in the complex, which was observed in the gel loading slot at 37 degrees C. At 20 degrees C, DNA was found to be partially dissociated from the complex by the appearance of the same band as DNA in the control experiment. These results clearly show that complex formation/dissociation was modulated by temperature alteration. The transfection efficiency of polymer-plasmid complexes was evaluated in COS-1 cells using pCMV-lacZ plasmid, encoding for beta-galactosidase as a reporter gene. The transfection efficiency of PDMAEMA homopolymer incubated at 37 degrees C for 48 h was greater than that incubated at 20 degrees C for 3 h and 37 degrees C for 45 h. In contrast, the transfection efficiency of P(IP-8DA-11BM) incubated at 20 degrees C for 3 h and 37 degrees C for 45 h was much higher than that incubated at 37 degrees C for 48 h. Such an increased transfection efficiency on lowering the temperature is considered to be due to appropriate formation/dissociation control of P(IP-8DA-11BM)-DNA complexes.     

Stability of cefepime in peritoneal dialysis solution.

OBJECTIVE: To determine the stability of cefepime in peritoneal dialysis solution. DESIGN: Cefepime HCl was added to premade bags of Delflex peritoneal dialysis solution with 1.5% dextrose to produce a cefepime concentration of approximately 100 microg/mL. Peritoneal dialysis solution bags were stored at 4, 25, and 37 degrees C to simulate refrigeration, room temperature, and body temperature, respectively. Samples were drawn at scheduled times up to 336, 168, and 48 hours, respectively, after the addition of cefepime HCl. Cefepime concentrations were measured by HPLC. SETTING: This study was performed at a university-affiliated tertiary care hospital. OUTCOME MEASURE: If the mean concentration of the samples at a given time and condition was >90% of the initial concentration, cefepime was considered stable at that time and condition. RESULTS: The mean HPLC results for samples drawn at each time and condition were all >90%. CONCLUSIONS: Cefepime is stable in peritoneal dialysis solution with dextrose 1.5% for 14 days refrigerated, seven days at room temperature, and 48 hours at 37 degrees C.     

Sympathetic nervous system "switch off" with severe hypothermia

Hypothermia occurs frequently in the critically ill patient, yet little is known about the endogenous catecholamine response to this stress. To study this problem, we measured heart rate (HR), mean arterial blood pressure (MAP), and plasma levels of norepinephrine (NE) and epinephrine (Epi) in subhuman primates (baboons) during progressive hypothermia from 37 degrees to 29 degrees C and then during rewarming to 37 degrees C. As the core temperature decreased from 37 degrees to 33 degrees C, HR and MAP increased significantly (p less than 0.05), but as core temperature further decreased from 33 degrees to 29 degrees C, the HR and MAP fell to prehypothermic levels. Plasma concentrations of NE and Epi increased significantly (p less than 0.01) as core temperature fell from 37 degrees to 31 degrees C, but as core temperature dropped from 31 degrees to 29 degrees C, plasma NE and Epi levels decreased towards prehypothermic concentrations. These findings indicate that the sympathetic nervous system (SNS) responds quickly to hypothermia but may be "switched off" at a threshold temperature of about 29 degrees C. We speculate that hypotensive patients with temperatures less than or equal to 29 degrees C may benefit from infusions of exogenous catecholamines, especially if there have been only minimal benefits achieved with conventional therapy such as fluids, and an increase in ambient temperature.     

Studies on rat complement. I. Immune adherence and immune hemolysis activities of rat serum.

The measurement of immune adherence reactivity of rat complement is possible at 20 degrees C but not at 37 degrees C. At 37 degrees C, EA rat C1423b site was destroyed by C3b inactivator present in rat serum. The optimal temperature for immune hemolysis reactivity of rat serum is either at 20 degrees C or 21 degrees C and dose response curve showed Von Krough equation with 1/n = 0.25 +/- 0.02. Al lower temperature, rat complement showed much more effective formation of C3 site to reacti with human erythrocyte in immune adherence as compared with guinea pig complement. The measurement of immune adherence reactivity of rat complement was not possible due to C3b inactivator at 37 degrees C but possible at 20 degrees C. It is possible due to lowering the reactivity of C3b inactivator and keeping the reactivity to form active C3b site in immune adherence reaction. Rat complement is more effective to make C3 site as compared with guinea pig complement. This explains the reason why EDTA rat serum has known to be most effective source of late acting complement for measurement of C1 and C2.     

Stability of moxifloxacin injection in peritoneal dialysis solution bags (Dianeal PD1 1.36% and Dianeal PD1 3.86%)

BACKGROUND AND OBJECTIVE: Moxifloxacin is a new fluorquinolone with broad-spectrum activity. It is suitable for treating peritonitis in peritoneal dialysis (PD) patients. The objective of this study was to test stability of moxifloxacin in PD solutions stored at different temperatures. METHODS: Dialysis solution bags were used at two glucose concentrations; Dianeal PD1 1.36% and Dianeal PD1 3.86%. Moxifloxacin solution (2%) was injected into nine 2-L bags of Dianeal PD1 1.36% and nine bags of Dianeal PD1 3.86% under aseptic conditions to achieve a nominal concentration of 25 mg/L. Three bags of Dianeal PD1 1.36% and three bags of Dianeal PD1 3.86% were stored at each of three temperatures (4, 25 and 37 degrees C) and the same way for. Duplicate samples (2 mL) were taken at different times and precipitation, cloudiness, colour and pH was analysed. Moxifloxacin concentrations were measured using a modified HPLC method. RESULTS: The mean moxifloxacin concentration in the Dianeal PD1 1.36% solution remained > or =90% of the initial concentration for 14 days at 4 degrees C, 7 days at 25 degrees C and 3 days at 37 degrees C. For Dianeal PD1 3.86% moxifloxacin concentrations remained > or =90% for 14 days at 4 degrees C, 3 days at 25 degrees C and 12 h at 37 degrees C. CONCLUSIONS: Moxifloxacin shows sufficient stability in both PD bags for use in PD patients.     

Transcutaneous measurement of the oxygen partial pressure using argon to correct for the oxygen consumption of the probe

The oxygen consumption of a transcutaneous probe creates an oxygen diffusion gradient between the skin capillaries and the probe, and this gradient causes the ratio between the oxygen partial pressure at the surface of the transcutaneous probe and the mean capillary pO2 to be less than 1. The ratio is usually increased towards unity by heating the skin to 43-45 degrees C, but this method introduces both practical and theoretical complications: the risk of skin burns and the increase in pO2 over the value in the blood at 37 degrees C. We present a new method to evaluate the ratio between the oxygen partial pressure at the surface of the transcutaneous probe and the mean capillary pO2. The method was used in measurements of the mean capillary pO2 in the skin of eight volunteers with a low-temperature probe (40 degrees C). The mean value of the ratio was 0.56 with a considerable variation from one person to another and from one skin location to another.