Investigation of insulin resistance during diabetic ketoacidosis: role of counterregulatory substances and effect of insulin therapy.

It has been generally accepted that insulin resistance (IR) exists in diabetic subjects during episodes of ketoacidosis (DKA). However, little experimental data exist regarding this question. We have studied IR in nine untreated diabetic subjects (mean age 20 yr) both during their initial episode of DKA and after 2–7 wk of insulin therapy. The experimental protocol consisted of a 150-min intravenous infusion of glucose (6 mg/kg/min) and insulin (80 mU/min). Under these conditions steady-state plasma glucose (SSPG) and insulin (SSPI) levels were reached by 90 min and maintained for the duration of the study. Since all subjects achieved similar SSPI and all received the same glucose load, the SSPG could be used as a measure of an individual's IR. In addition, steady-state plasma levels of glucagon, cortisol, growth hormone, and free fatty acids were measured in an attempt to gain insight into their roles in the maintenance of IR during DKA. Although mean (± SE) SSPI levels were the same during both study periods (93 ± 4 versus 92 ± 4 μU/ml), there was a marked difference between the initial and posttherapy SSPG levels for the nine subjects 342 ± 32 versus 104 ± 16 mg/100 ml,p < .001). Mean steady-state plasma levels of growth hormone, corticol, and free fatty acids were significantly higher during the initial studies, but only cortisol and free fatty acid levels correlated significantly with their corresponding SSPG levels. Steady-state plasma glucagon levels were the same during both study periods, and individual levels did not correlate with associated SSPG levels. These studies demonstrate that significant IR was present in these subjects during DKA as compared to the posttherapy period. Furthermore, the results suggest that while increased plasma concentrations of cortisol and free fatty acids may be involved in the maintenance of IR during DKA, elevated levels of plasma growth hormone and glucagon are not necessary for this phenomenon.     

Protective effect and mechanism of stronger neo-minophagen C against fulminant hepatic failure

AIM： To investigate the protective effect of stronger neo-minophafen C （SNMC） on fulminant hepatic failure （FHF） and its underlying mechanism.
METHODS： A mouse model of FHF was established by intraperitoneal injection of galactosamine （D-Gal N） and lipopolysaccharide （LPS）. The survival rate, liver function, inflammatory factor and liver pathological change were obtained with and without SNMC treatment. Hepatoo/te survival was estimated by observing the stained mitochondria structure with terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate fluorescence nick end labeling （TUNEL） method and antibodies against cytochrome C （Cyt-C） and caspase-3.
RESULTS： The levels of plasma tumor necrosis factor alpha （TNF-α）, nitric oxide （NO）, ET-1, interleukin-6 （IL-6）, and the degree of hepatic tissue injury were decreased in the SNMC-treated groups compared with those in the model group （P 〈 0.01）. However, there were no differences after different dosages administered at different time points. There was a significant difference in survival rates between the SNMC-treated groups and the model group （P 〈 0.01）. The apoptosis index was 32.3% at 6 h after a low dose of SNMC, which was considerably decreased from 32.3% ± 4.7% vs 5% ± 2.83% （P 〈 0.05） to 5% on d 7. The expression of Cyt-C and caspase-3 decreased with the prolongation of therapeutic time. Typical hepatocyte apoptosis was obviously ameliorated under electron microscope with the prolongation of therapeutic time. CONCLUSION： SNMC can effectively protect liver against FHF induced by LPS/D-Gal N. SNMC can prevent hepatocyte apoptosis by inhibiting inflammatory reaction and stabilizing mitochondria membrane to suppress the release of Cyt-C and sequent activation of caspase-3.     

阿司匹林对游离脂肪酸引起的大鼠肝细胞胰岛素抵抗的保护作用

探讨游离脂肪酸和阿司匹林对大鼠肝细胞胰岛素受体底物2(IRS -2)的蛋白质含量及其酪氨酸残基磷酸化水平的影响,结果提示游离脂肪酸可能通过抑制IRS- 2酪氨酸残基磷酸化和降低IRS -2蛋白质含量引起肝细胞胰岛素抵抗,阿司匹林能防治游离脂肪酸引起的肝细胞胰岛素抵抗。     

Protective effect of thiopental against cerebral ischemia during circulatory arrest.

BACKGROUND: One of the most important disadvantages of the hypothermic circulatory arrest technique is the limited time allowable for circulatory arrest. Thiopental is usually used to protect the brain against ischemic injuries. However, it remains uncertain how well thiopental reduces cerebral metabolism. We investigated its effectiveness by comparing outcomes after different doses. METHODS: Fifty patients who underwent aortic arch repair with hypothermic circulatory arrest had their records reviewed. Electroencephalograms (EEG) and partial pressures of oxygen in the internal jugular vein (PjO2) were monitored. Following confirmation of total disappearance of EEG activity, 15 or 30 mg/kg thiopental was administered before circulatory arrest Th duration of circulatory arrest ranged from 16 to 77 min. RESULTS: Hospital mortality rate was 10% and 4 (8%) patients developed neu-rologic complications, but 3 of them were transient. After thiopental infusion, PjO2 increased significantly from 430 to 499mmHg (p <0.01), indicating that thiopental reduces cerebral oxygen consumption. The rate of the decrease in PjO2 during circulatory arrest was slower with the higher thiopental dose, suggesting that thiopental lowered the cerebral metabolic rate of oxygen during circulatory arrest. CONCLUSION: It appears that thiopental has protective effects against cerebral ischemia under profound hypothermia.     

Suppression of counterregulatory hormone response to hypoglycemia by insulin per se

Although assessment of counterregulatory hormone responses to hypoglycemia relies upon insulin to lower the glucose level, it is not known if the exogenous insulin does used itself influences the magnitude of the hormone response. To assess this, 12 normal subjects randomly received 2 hypoglycemic clamp studies in which the only variable was the insulin dose (0.6 or 5.0 mU/kg-min). Despite 10-fold differences in circulating insulin (265 +/- 29 vs 2576 +/- 222 pmol/L respectively), the hypoglycemic stimulus did not vary. Glucose levels fell over one hour, and then were maintained for two hours at the same hypoglycemic plateau (approximately 3.1 mmol/L for each study) by a variable glucose infusion. Although basal counterregulatory hormone levels in low and high dose studies were indistinguishable, during hypoglycemia the response of epinephrine, growth hormone, and glucagon was significantly suppressed when the degree of hyperinsulinemia was increased. We conclude that raising the magnitude of hyperinsulinemia suppresses the magnitude of the counterregulatory hormone response to hypoglycemia in normal subjects. This modulating effect of insulin per se is yet another variable in the interpretation of hypoglycemic counterregulation.     

Protective effect of idebenone against hypoxia in mice

The effects of idebenone on survival time of mice subjected to hypoxia induced by N2 and CO2 inhalation and KCN injection were studied. Idebenone (10, 20, 50 and 100 mg/kg, i.p.) prolonged the survival time of mice exposed to a hypoxic condition (98% N2, 2% O2) in a dose-dependent manner: significant prolongations were observed at doses higher than 20 mg/kg. The drug also exerted a similar elongation effect at the same doses under conditions of 100% CO2 gas inhalation and KCN injection (3 mg/kg, i.v.). The results suggest that idebenone protects against hypoxia by improving cerebral energy metabolism.     

Protective effect of taurine against isoprenaline-induced myocardial damage

Summary The effect of the sulfur amino acid, taurine, was examined on histological and biochemical changes induced by a toxic dose of isoprenaline in chick hearts. Isoprenaline treatment (80 or 240 mg/kg id twice daily for 4 days) caused a dose-dependent increase in heart weight and decrease in myocardial ATP. Isoprenaline administration (240 mg/kg id twice daily) produced necrotic changes in hearts, such as eosinophilic degeneration, myolysis, interstitial oedema, fibrosis, and inflammatory cell infiltration. Substantial accumulation of calcium was also observed. Taurine content of the heart was not significantly decreased. Parenteral administration of taurine (200 mg/day for 7 days) partially protected against these necrotic changes induced by isoprenaline. It is suggested that the protective effect of taurine against isoprenaline-induced myocardial injury might be due in part to the prevention of the massive overloading with calcium which is thought to cause myocardial cell necrosis.     

Protective effect of chitosan treatment against acetaminophen-induced hepatotoxicity

Acetaminophen (APAP) is the most commonly reported toxic ingestion in the world. Severe liver injury resulting from overdose or chronic use of APAP remains a significant clinical problem. In recent years, the mechanisms underlying liver injury caused by APAP have become much better understood. We have studied the protective effect of chitosan supplementation against APAP-induced hepatotoxicity with respect to changes in the levels of total and lipid-bound sialic acid in the serum and in the liver tissue and changes in the activity of diagnostic marker enzymes, lipid peroxidation, and ceruloplasmin oxidase enzyme in normal and experimental groups of rats. During the experimental period, chitosan (200 mg/kg body weight per day) was administered to APAP + chitosan-treated rats by oral gavage. Results showed that treatment with APAP induced a significant increase in the serum alanine aminotransferase and alkaline phosphatase activities, in total and lipid-bound sialic acids levels, and in the liver lipid peroxide content. The administration of chitosan significantly prevented APAP-induced alterations in the levels of diagnostic marker enzymes, total sialic acid, lipid-bound sialic acid, and malondialdehyde in the experimental groups of rats. Furthermore, chitosan administration increased the activity of ceruloplasmin oxidase. In conclusion, our results suggest that chitosan has a protective effect on APAP-induced hepatic injury in rats. The study sheds light on the therapeutic potential of chitosan in an APAP-induced hepatotoxicity model.     

Protective effect of Rosa laevigata against amyloid beta peptide-induced oxidative stress.

The amyloid beta (Abeta) peptide is known to increase free radical production in nerve cells, leading to cell death. To investigate the effect of Rosa laevigata against Abeta-induced oxidative damage, in vitro assays and in vivo behavioral tests were performed. R. laevigata showed cell protective effects against oxidative stress-induced cytotoxicity. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) reduction assay exhibited significant increase in cell viability when rat pheochromocytoma (PC 12) cells were treated with R. laevigata extracts. Administration of R. laevigata extracts to mice significantly reversed the Abeta-induced learning and memory impairment in in vivo behavioral tests. These results suggest that R. laevigata extracts can reduce the cytotoxicity of Abeta in PC 12 cells, possibly by the reduction of oxidative stress, and these extracts may be useful in the prevention of Alzheimer's disease.     

The Protective effect ofd-sotalol against hypoxia-induced myocardial uncoupling

Summary The effects ofd-sotalol on intercellular electrical coupling and ultrastructure under hypoxic conditions were investigated in myocardial samples from eight young (1–2 months) and four older (10–12 months) guinea pigs. A right ventricular muscle strip was kept simultaneously in two divided chambers and superfused with normoxic and/or hypoxic (97% N₂+ 3% C_O2) Krebs solution. Hypoxia caused shortening of action potential duration (APD) and electrical cellto-cell uncoupling. If the uncoupling appeared after short-term hypoxia (less than 30 min), administration of 3.10^–7M ofd-sotalol to the hypoxic perfusate led to a recovery of electrical coupling. Transmission electron microscopy revealed moderate reversible ultrastructural alterations of the cardiomyocytes. No apparent changes in intercellular junctions were observed. The recoupling effect of sotalol decreased with the time of hypoxia as the ultrastructural damage progressed. After prolonged hypoxia (more than 30min), cardiomyocytes were markedly injured, intercellular junctions were severely affected, and gap junctions occurred less frequently. In these cases, administration ofd-sotalol caused only transient recoupling. After 1h of hypoxia, no recoupling was observed. Pretreatment withd-sotalol prevented hypoxia-induced electrical uncoupling and markedly attenuated ultrastructural damage, although shortening of APD still persisted. Our results indicate that the cardioprotective effect ofd-sotalol on electrical intercellular coupling is closely associated with sotalol-induced prevention of the ultrastructural damage. Considering previous results, we suggest that this protective effect ofd-sotalol may be related to its ability to increase intracellular cyclic adenosine monophosphate and, thereby, to decrease cytosolic free Ca. These effects can explain the antiarrhythmic and defibrillating properties ofd-sotalol.     

Protective effect of androgens against inflammation induced cartilage degradation in male rodents.

OBJECTIVES--Rheumatoid arthritis (RA) is a disease which predominantly affects women. Interestingly, low serum androgen levels and clinical improvement with androgen replacement have been reported in male patients. The aetiopathogenic role of sex hormones in arthritis and their potential long term effects on joint destruction and disability remains unclear, however. This study was designed to investigate the potential influence of sex hormones on inflammation induced cartilage degradation in male rodents. METHODS--An in vivo model of cotton wrapped cartilage implants was used to assess the effects of androgen, oestradiol, and progesterone on inflammation induced cartilage degradation, and in vitro techniques were used to investigate the direct actions on cartilage metabolism and cytokine production in male animals. RESULTS--Orchidectomy resulted in accelerated cartilage damage which was reversed by replacement of physiological levels of androgens. Granulomatous tissue from castrated male rodents produced higher amounts of interleukin 1. Sex hormones reduced spontaneous proteoglycan loss in vitro but did not interfere with the effects of interleukin 1 on cultured cartilage. CONCLUSIONS--Androgens appear to protect cartilage from inflammation induced breakdown in male animals. These results support a pathogenic role for hypoandrogenism in rheumatoid arthritis and suggest that long term androgen replacement may help prevent joint damage and disability.     

Protective effect of pneumococcal vaccine against death by pneumonia in elderly subjects.

The present study assessed the effectiveness of the 23-valent pneumococcal polysaccharide vaccine to prevent pneumonia and death in older adults in a first-time report between January and December 2002. A prospective cohort study was conducted including all individuals>or=65 yrs of age assigned to one of eight primary care centres in Tarragona, Spain (n=11,241). The primary outcomes were community-acquired pneumonia (hospitalised or outpatient) and death from pneumonia. All pneumonias were validated by checking clinical records. The association between the pneumococcal vaccination and the risk of each outcome was evaluated by means of multivariate Cox proportional-hazard models, adjusted by age, sex, influenza vaccination status, comorbidity and immunological status. Pneumococcal vaccination did not alter the risk of hospitalisation from pneumonia (hazard ratio (HR): 0.80; 95% confidence interval (CI): 0.50-1.28) or overall pneumonia (HR: 0.86; 95% CI: 0.56-1.31), but the vaccine was associated with considerable reductions of death risk from pneumonia (HR: 0.28; 95% CI: 0.09-0.83). In conclusion, these results suggest that pneumococcal polysaccharide vaccine may not be effective in reducing the incidence of pneumonia, but may be able to diminish the severity of the infection. These findings support the effectiveness of the pneumococcal polysaccharide vaccine to prevent mortality caused by pneumonia in older adults, providing a new argument to recommend systematic vaccination in the elderly.     

Protective effect of diltiazem against acetaminophen hepatotoxicity in mice

There is evidence that an increase in cytosolic Ca++ concentration is a terminal event in the progression to cell death in toxic liver injury. We have compared the hepatoprotective effects of N-acetylcysteine (1 g/kg) and the calcium channel blocking agent, diltiazem (24 mg/kg), when given at 30 min, 3 h and 6 h after single intraperitoneal overdoses of acetaminophen (500 mg/kg) in mice. Overall beneficial effects on mortality, liver necrosis score, and plasma alanine aminotransferase (ALT) activity were found in diltiazem-treated mice 24 h after acetaminophen overdose. However, the most marked effects were obtained when diltiazem was given 6 h after acetaminophen. N-acetylcysteine was more effective than diltiazem at 30 min and 3 h, although it was less effective at 6 h. Mean plasma concentrations of the mercapturate metabolite (hepatic oxidative metabolism) were not significantly different among animals receiving acetaminophen alone or in combination with diltiazem, which suggests that the hepatoprotective effects of diltiazem are not exerted by inhibition of drug metabolic enzymes.     

复方甘草酸苷对小鼠暴发性肝功能衰竭保护作用及机制研究

目的　探讨复方甘草酸苷(SNMC)对小鼠暴发性肝功能衰竭(FLF)的保护作用及可能机制。方法　用D- 氨基半乳糖和脂多糖腹腔注射构建肝功能衰竭的小鼠模型,同时用SNMC对治疗组小鼠进行保护,观察各组小鼠存活率、肝功能、各种炎症因子及肝脏病理变化;电镜下观察线粒体结构的改变;应用末端转移酶标记技术(TUNEL)检测肝细胞原位凋亡的情况;应用免疫组化法分别检测肝组织中细胞色素C和天冬氨酸半胱氨酸蛋白酶3(caspase 3)的表达。结果　D 氨基半乳糖和脂多糖可以构建FLF模型,SNMC不同剂量组及不同给药时间组在降低酶学指标及血浆肿瘤坏死因子(TNF)- α、NO、内皮素(ET) -1、白细胞介素(IL) 6 水平,改善肝组织的损伤程度方面与模型组比较(多组间方差分析)差异均有统计学意义(P<0.01)。不同剂量和不同给药时间之间差异无统计学意义(P>0.05)。模型组和保护组之间的存活率差异有统计学意义(P<0.01)。同时给药小剂量组随着SNMC治疗时间的延长,凋亡指数逐渐降低,由6- h的32.3%降至7 d的5%(P<0.05);细胞色素C和caspase 3随治疗时间延长表达逐渐减少;电镜可见典型的肝细胞凋亡随治疗时间的延长明显改善。结论　SNMC对小鼠FLF有明显的保护作用,其机制可能是抑制各种因素所介导的炎症反应及通过稳定线粒体膜抑制细胞色素     

复方甘草酸苷对小鼠暴发性肝功能衰竭的保护作用

目的 探讨复方甘草酸苷(SNMC)对小鼠暴发性肝功能衰竭(FLF)的保护作用。 方法 用D-氨基半乳糖和脂多糖腹腔注射构建FLF小鼠模型。观察SNMC对实验性FLF小鼠血清丙氨酸氨基转移酶(ALT)、白蛋白(Alb)、总胆红素(TBil)、肿瘤坏死因子α(TNFα)、一氧化氮(NO)、内皮素-1(ET-1)、白细胞介素-6(IL-6)和肝脏病理情况及存活率的影响。 结果 D-氨基半乳糖和脂多糖可以构建FLF小鼠模型,SNMC大、中、小剂量组及不同给药时间组在降低酶学指标及血清TNF α(F=52.84,P<0.01)、NO(F=15.81,P<0.01)、ET-1(F=15.68,P<0.01)、IL-6(F=15.32,P<0.01)水平,以及改善肝组织的衰竭程度方面(F=4.51,P<0.01)与模型组比较,差异均有统计学意义。SNMC大、中、小剂量以小剂量较好,不同给药时间以同时给药较好,但不同剂量和不同给药时间之间差异无统计学意义。模型组和保护组之间存活率的差异有统计学意义(P<0.01)。 结论 结果表明SNMC对FLF小鼠有明显保护作用,可改善D-氨基半乳糖和脂多糖所致的肝细胞病理性凋亡及坏死程度,并抑制各种因子所介导的炎症反应,从而降低FLF的病死率。     

Protective effect of dehydroepiandrosterone against lipid peroxidation in a human liver cell line.

OBJECTIVE: Dehydroepiandrosterone (DHEA) is a widely studied steroid hormone with multi-functional properties. Reports suggest that some of the many activities of DHEA are due to its protective effect against lipid peroxidation. Nevertheless, the antioxidant properties of DHEA are still the subject of debate. The aim was to evaluate whether its two opposed effects on lipid peroxidation reported in the literature may be dependent on schedule and doses used. METHODS: Chang liver cells, a line derived from normal human liver, were grown in media containing either no steroids (control) or DHEA at concentrations ranging from 0.1 micromol/l to 50 micromol/l. At specific times, cultures were halted and cells received a pro-oxidant stimulus (cumene (CuOOH) 0.5 mmol/l), at which time cell viability (by trypan blue staining and lactate dehydrogenase (LDH) release) and thiobarbituric acid reactive substances (TBARS) concentration (spectrophotometrical assay) were evaluated. RESULTS: At concentrations ranging from 0.1 micromol/l to 1 micromol/l, DHEA protects Chang liver cells against lipid peroxidation and/or death induced by cumene. This effect disappears if the concentration is increased to 10 micromol/l; at higher concentrations (50 micromol/l) a pro-oxidant/cytotoxic effect of DHEA appears. CONCLUSIONS: DHEA exhibits two opposed effects on lipid peroxidation; depending on its concentration it acts either to limit or to induce oxidative stress. The threshold concentration at which the pro-oxidant activity of DHEA prevails is not far in excess of that having an antioxidant effect. Either effect of DHEA on lipid peroxidation is only evident after a 'lag-phase'.     

人胰岛素在磺脲类药物继发失效中的疗效观察

磺脲类药物的继发失效(SFS)每年以5%～10%的发生率递增,我们对30例SFS患者改用人胰岛素(诺和灵)治疗,对其疗效进行了观察.现报道如下.