Characterization of low dose streptozotocin-induced progressive diabetes in mice

Our previous study indicated that a single i.p. injection of 100 mg/kg streptozotocin (STZ) is able to induce slowly progressive diabetes mellitus in adult ICR mice. In the present study, the non-fasting serum insulin levels of the mice administered 100 mg/kg STZ were normal throughout the 24-week-observation after STZ injection. In the STZ-administered mice, the area of islets and the number of insulin-immunoreactive cells (beta-cells) were normal at 1 week and then continued to decrease gradually as the time went on. In contrast, there was a relative increase in the number of glucagon-immunoreactive cells (alpha-cells) in these mice. In addition, in the STZ-administered mice, the degree of glucose tolerance continued to reduce from 2 weeks till 12 weeks when the experiment terminated. The rise in serum insulin levels stimulated by glucose in the STZ-administered mice began to subside from about 2 weeks and had completely ceased by 12 weeks. These results indicate that 100 mg/kg STZ-induced diabetic mouse model is non-insulin-dependent diabetes, which is characterized by impaired insulin response to glucose stimulation.     

Antidiabetic effects of chitosan oligosaccharides in neonatal streptozotocin-induced noninsulin-dependent diabetes mellitus in rats

The antidiabetic effect of chitosan oligosaccharide (COS) was investigated in neonatal streptozotocin (STZ)-induced noninsulin-dependent diabetes mellitus rats. The fasting glucose level was reduced by about 19% in diabetic rats after treatment with 0.3% COS. Glucose tolerance was lower in the diabetic group compared with the normal group. After diabetic rats had been treated with 0.3% COS for 4 weeks, glucose tolerance increased significantly versus the diabetic control group, and glucose-inducible insulin expression increased significantly. In addition, fed-triglyceride (TG) levels in diabetic rats drinking 0.3% COS were reduced by 49% compared with those in diabetic control rats. The cholesterol levels of animals treated with COS were reduced by about 10% in fed or fasting conditions versus the corresponding controls, although the difference was not statistically significant. It was found that COS has a TG-lowering effect in diabetic rats, and that COS reduces signs of diabetic cardiomyopathy such as vacuolation of mitochondria and the separation and degeneration of myofibrils. In conclusion, these results indicate that COS can be used as an antidiabetic agent because it increases glucose tolerance and insulin secretion and decreases TG.     

Low molecular weight chitosan inhibits obesity induced by feeding a high-fat diet long-term in mice

Three low molecular weight chitosans (molecular weight: 21, 46 and 130 kDa) obtained by enzymatic hydrolysis of a high molecular weight chitosan (average molecular weight: 650 kDa) had low viscosity and were water-soluble. The effects of these water-soluble chitosans on pancreatic lipase (in-vitro) and the elevation of plasma triacylglycerol concentration after the oral lipid tolerance test were examined in mice. The water-soluble 46-kDa chitosan was the most effective at inhibiting pancreatic lipase activity (in-vitro) and plasma triacylglycerol elevation after the oral lipid tolerance test. Based on this result, the effects of the 46-kDa chitosan on increases in bodyweight, various white adipose tissue weights, and plasma and liver lipids were examined in mice fed a high-fat diet for 20 weeks. Water-soluble 46-kDa chitosan (300 mg kg(-1), twice daily) prevented increases in bodyweight, various white adipose tissue weights and liver lipids (cholesterol and triacylglycerol) in mice fed a high-fat diet, and further increased the faecal bile acid and fat. The results suggest that the lipid-lowering effects of the 46-kDa chitosan may be mediated by increases in faecal fat and/or bile acid excretion resulting from the binding of bile acids, and by a decrease in the absorption of dietary lipids (triacylglycerol and cholesterol) from the small intestine as a result of the inhibition of pancreatic lipase activity. Water-soluble 46-kDa chitosan (100 and 300 mg kg(-1), twice daily) did not cause liver damage with the elevation of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase, or kidney damage with the elevation of blood nitrogen urea. It was concluded that water-soluble 46-kDa chitosan is a safe functional food.     

A comparative study on hypoglycemic and hypocholesterolemic effects of high and low molecular weight chitosan in streptozotocin-induced diabetic rats.

The hypoglycemic and hypocholesterolemic effects of high and low molecular weight chitosan were evaluated in streptozotocin (STZ)-induced diabetic rats. Rats were divided into three groups of normal rats (Experiment I) and three groups of diabetic rats (Experiment II). The first group received a cellulose (control) diet, the second group received a low MW (1.4 x 10(4)Da) chitosan diet and the third group received a high MW (1.0 x 10(6)Da) chitosan diet. All three diets were containing 0.5% cholesterol. Experiment I: rats fed with high MW or low MW chitosan diet had increased high density lipoprotein (HDL) cholesterol. However, chitosan did not affect plasma glucose in normal rats. Experiment II: significantly decreased plasma glucose and total cholesterol and increased HDL cholesterol and fecal cholesterol excretion were observed in diabetic rats fed with high MW chitosan diet than animals fed with cellulose diet. However, no statistical significant difference in plasma glucose and total cholesterol was observed in diabetic rats fed with low MW chitosan. The total content of SCFAs in cecum was significantly increased and the ratio of acetate to propionate was slight but significantly decreased in diabetic rats after consuming high MW chitosan diet. The activities of hepatic hexokinase were significantly increased and the intestinal disaccharidases including sucrase and maltase were significantly decreased in normal and diabetic rats fed with high MW chitosan diet. Results obtained from the present study demonstrated the potential of high MW chitosan in reducing hyperglycemia and hypercholesterolemia in STZ-induced diabetic rats.     

Interaction of indomethacin with low molecular weight chitosan,and improvements of some pharmaceutical properties of indomethacin by low molecular weight chitosans

The interaction of four kinds of low molecular weight chitosans, which were different in molecular weight and degree of deacetylation, were studied in solution and the solid state using an anti-inflammatory drug, indomethacin (IM), as an acidic model molecule. The solubility of IM enhanced with increasing concentration of low molecular weight chitosan, especially C-I which had the lowest molecular weight and least degree of deacetylation. The C-I crystal complex was obtained in a molar ratio of 16:1 (IM: C-I) from aqueous solution. The data suggested that the acetyl group and amino group of chitosan played an important role in the complexation. The IM dissolution rates from kneaded mixtures with low molecular weight chitosans were enhanced in the order of C-I >C-II >C-III >C-IV (molecular weight: C-IV >C-III >C-II >C-I). The oral absorption rate of IM from C-I kneaded mixture was improved compared with IM alone.     

New model of progressive non-insulin-dependent diabetes mellitus in mice induced by streptozotocin.

This study was designed to clarify the relationship between streptozotocin (STZ) dosage (100, 150 and 200 mg/kg i.p.) and the resulting diabetogenic response in mice (8-week-old male ICR). In this experiment, we found that a single i.p. injection of 100 mg/kg STZ is able to induce progressive diabetes mellitus, in which non-fasting serum glucose levels begin to rise from 3 weeks and continue to rise throughout the experimental period until 9 weeks. The non-fasting serum insulin levels of 100 mg/kg STZ-treated mice were normal during the experimental period. In addition, the population of insulin-immunoreactive cells (beta cells) in the islets of pancreata was slightly less than in normal mice at 9 weeks. In 200 mg/kg STZ-treated mice, on the other hand, the insulin levels were below measurable values and insulin-immunoreactive cells were not observed. It is concluded from these results that the progressive diabetic mouse model induced by a single i.p. injection of 100 mg/kg STZ, unlike 200 mg/kg STZ-induced diabetes which is insulin-dependent, is non-insulin-dependent.     

Adrenergic receptors and the onset of streptozotocin-induced diabetes in mice

Treatment with yohimbine, an alpha 2-adrenergic blocker, prior to the injection of a subdiabetogenic dose of streptozotocin (STZ) produced hyperglycemia and hypoinsulinemia in mice 7 days later. Prazosin, an alpha 1-adrenergic blocker, was ineffective. The capacity of phentolamine and phenoxybenzamine to potentiate the diabetogenic effect of STZ was intermediate between that of yohimbine and prazosin. Propranolol and hexamethonium inhibited the potentiating action of yohimbine. Yohimbine enhanced the potentiating effect of isoproterenol on the STZ-induced diabetes. Acute changes in phase glucose and insulin levels induced by STZ were potentiated by yohimbine but not by prazosin. The insulin releasing ability of the pancreatic islets 7 days after STZ was all but lost in mice pretreated with yohimbine but not with prazosin. These results suggest that the beta- and alpha 2-, not alpha 1-adrenergic system which modulates insulin release from pancreatic islets influences the response to the diabetogenic action of STZ in mice.     

Effect of streptozotocin-induced diabetes mellitus on the pharmacokinetics of nelfinavir in rats

The HIV protease inhibitor, nelfinavir (NFV), has been used widely for HIV infection. The drug exhibits high binding characteristics to serum protein (unbound fraction: 0.01). The effect of experimentally induced diabetes mellitus on the pharmacokinetics of NFV was investigated, focusing on the change of protein-binding due to the glycosylation of albumin in streptozotocin-induced diabetes mellitus rats (diabetic rats). The unbound fraction of NFV in diabetic rats (0.04) was greater than that in the control (0.015). In diabetic rats, although the AUC of NFV was decreased after both intravenous (control: 1.75±0.08, diabetic: 1.36±0.17 µg h/ml) and intraduodenal (control: 1.69±0.25, diabetic: 1.19±0.39 µg h/ml) administrations, the unbound AUC was increased significantly (intravenous, control: 0.026±0.001, diabetic: 0.054±0.007 µg h/ml, intraduodenal, control: 0.025±0.004, diabetic: 0.048±0.016 µg h/ml). The unbound total clearance (control: 131.3±6.0, diabetic: 64.3±8.0 l/h/kg) and the unbound steady state distribution volume (control: 274.0±18.0, diabetic: 123.0±14.0 l/kg) were decreased significantly; therefore, greater pharmacological effects can be expected in diabetes mellitus. The contribution of increasing the unbound fraction to these results was significantly higher. In addition, there were no significant differences in the systemic and hepatic availability, peak time and mean absorption time between the diabetic and control rats, suggesting that diabetes mellitus did not affect the absorption of NFV. Copyright © 2008 John Wiley & Sons, Ltd.     

奥扎格雷钠和低分子肝素钙治疗进展性脑梗死疗效观察

目的 探讨奥扎格雷钠联合低分子肝素钙治疗进展性脑梗死的临床效果.方法 将在本院治疗的进展性脑梗死患者90例随机分为观察组和对照组.对照组给予常规治疗措施,观察组在对照组治疗的基础上给予奥扎格雷钠联合低分子肝素钙治疗.结果 治疗后观察组患者NDS、NIHSS及ADL评分明显优于对照组(P<0.05).治疗后两组患者INR...     

A method for direct preparation of chitosan with low molecular weight from fungi.

By modifying the common method for the preparation of chitosan from fungi, low molecular weight chitosan with an average MW of 4.5 x 10(4) g/mol and a numerical MW of 1.7 x 10(4) g/mol can be directly extracted from the raw material without the need of thermal or chemical depolymerization. Based on the solubility of low molecular chitosan up to alkaline pH ranges, reprecipitation and washing with ethanol is required to keep the low molecular fraction within the preparation. The use of water for washing between the preparation steps would cause solving and discarding of the low molecular chitosan. The chitosan was analyzed by laser light scattering and 1H-NMR spectroscopy.     

Epigallocatechin gallate prevents autoimmune diabetes induced by multiple low doses of streptozotocin in mice

Cytokines produced by immune cells infiltrating pancreatic islets have been incriminated as important mediators of beta-cell destruction in insulin-dependent diabetes mellitus. In non insulin-dependent diabetes, cytokines are also associated with impaired beta-cell function in high glucose condition. By the screening of various natural products blocking beta-cell destruction, we have recently found that epigallocatechin gallate (EGCG) can prevent the in vitro destruction of RINm5F cell, an insulinoma cell line, that is induced by cytokines. In that study we suggested that EGCG could prevent cytokine-induced beta-cell destruction by down-regulation of nitric oxide synthase (NOS) through inhibition of NF-kappaB activation. Here, to verify the in vivo antidiabetogenic effect of EGCG, we examined the possibility that EGCG could also prevent the experimental autoimmune diabetes induced by the treatment of multiple low doses of streptozotocin (MLD-STZ), which is recognized as an inducer of type I autoimmune diabetes. Administration of EGCG (100 mg/day/kg for 10 days) during the MLD-STZ induction of diabetes reduced the increase of blood glucose levels caused by MLD-STZ. Ex vivo analysis of beta-islets showed that EGCG downregulates the MLD-STZ-induced expression of inducible NOS (iNOS). In addition, morphological examination showed that EGCG treatment ameliorated the decrease of islet mass induced by MLD-STZ. In combination these results suggest that EGCG could prevent the onset of MLD-STZ-induced diabetes by protecting pancreatic islets. Our results therefore revealed the possible therapeutic value of EGCG for the prevention of diabetes mellitus progression.     

小剂量肝素治疗婴幼儿重症肺炎的临床观察

目的分析研究小剂量肝素在治疗婴幼儿重症肺炎中的作用。方法回顾性分析2009年4月至2010年4月期间在我院住院治疗的42例重症肺炎患儿的临床资料。42例婴幼儿重症肺炎用随机数字表法分成为治疗组21例和对照组21例,两组均给予常规抗感染及对症支持治疗,治疗组在此基础上辅以小剂量常肝素25U/kg。次脐周皮下注射,1次/d,7d为l个疗程。结果治疗组有效率95.24%,对照组有效率76.19%,两组比较差异有统计学意义(P<0.05)。结论脐周皮下注射肝素治疗婴幼儿重症肺炎疗效显著,且无明显副作用。     

Liposome coated with low molecular weight chitosan and its potential use in ocular drug delivery

In this study liposome coated with low molecular weight chitosan (LCH) was proposed and investigated its in vitro and in vivo properties, and its potential use in ocular drug delivery was evaluated. LCH with a molecular weight of 8 kDa was prepared and coated on liposome loaded with diclofenac sodium. The LCH coating changed the liposome surface charge and slightly increased its particle size, while the drug encapsulation was not affected. After coating, the liposome displayed a prolonged in vitro drug release profile. LCH coated liposome also demonstrated an improved physicochemical stability at 25 °C in a 30-day storage period. The ocular bioadhesion property was evaluated by rabbit in vivo precorneal retention, and LCH coated liposome achieved a significantly prolonged retention compared with non-coated liposome or drug solution. The LCH coating also displayed a potential penetration enhancing effect for transcorneal delivery of the drug. In the ocular tolerance study, no irritation or toxicity was caused by continual administration of LCH coated liposome in a total period of 7 days. In conclusion, the LCH coating significantly modified the properties of liposome and brought a series of notable advantages for ocular drug delivery.     

Low molecular weight quaternised chitosan (11): in vitro assessment of absorption enhancing properties

N-Trimethyl chitosan chloride (TMC; high molecular weight) and N-trimethyl chitosan oligosaccharide (TMO; low molecular weight) with different degrees of quaternisation were synthesised and evaluated for their absorption enhancing properties across mucosal epithelia. These quaternised chitosan derivatives (0.0625% w/v-0.5% w/v) showed a significant decrease in the transepithelial electrical resistance (TEER) of cultured rabbit tracheal epithelial cell monolayers as compared to the control. The degree of quaternisation and concentration of the compounds influenced the extent of the reduction in TEER. Higher degrees of quaternisation and an increase in the concentration of the compound were associated with a more pronounced reduction in the TEER. The TMO derivatives seemed to be more effective in lowering the TEER of tracheal cell monolayers as compared to the TMC polymers. Ciliary beat frequency (CBF) is the main defence mechanism of the respiratory tract and is therefore a useful parameter in evaluating the toxicity of nasally administered drugs and additives. The effect of the synthesised chitosan derivatives on the CBF of human nasal epithelial cells at pH 7.4 was determined by a method based on an analogue contrast enhancement technique. The TMO oligomers exhibited lower inhibition of the CBF of human nasal epithelial cells compared to that of the TMC polymers. It was proposed that this reduced effect on the CBF is due to the lower viscosity and molecular weight of TMO. However, no acute toxicity was found with any of the synthesised chitosan derivatives by means of the CBF tests conducted in this study.     

依达拉奉联合低分子肝素治疗急性进展性脑梗死的临床研究

目的探讨依达拉奉联合低分子肝素治疗急性进展性脑梗死的临床疗效。方法选取本院2009年11月～2011年12月收治的急性进展性脑梗死患者76例,将其随机分为两组,38例患者使用低分子肝素作为对照组,38例患者采用依达拉奉联合低分子肝素作为观察组,分析两组患者的临床指标,并进行神经功能缺损程度评分。结果观察组患者的活化部分凝血活酶时间为（32.5±7.1）s,长于对照组的（31.0±6.2）s,两组差异无统计学意义（P〉0.05）。观察组患者的血小板计数为（184.2±29.6）×109/L、总有效率为76.3%,均明显高于对照组的（146.7±31.4）×109/L、52.6%,观察组纤维蛋白原水平为（2.9±0.7）g/L、神经元特异性烯醇化酶水平为（10.7±2.9）μg/L、神经功能缺损程度评分为（10.7±2.8）分,均明显低于对照组的（3.3±1.4）g/L、（21.6±4.1）μg/L、（18.2±4.6）分,两组差异均有统计学意义（P〈0.05）。结论依达拉奉联合低分子肝素治疗急性进展性脑梗死可显著改善患者的神经功能,且安全有效。     

Prenatal and developmental effect of high molecular weight chitosan (HMWCS) to mice

High molecular weight chitosan (HMWCS) is effective at hemostasis and wound healing, and will be potentially used on injured internal organs. To study its prenatal and developmental effect in vivo, forty-four ICR pregnant mice per group were singly injected intraperitoneally at 0, 125, 500 or 2000 mg/kg body weight, respectively, on gestation day 6 (GD6). Clinical signs, reproductive capacity, fetus and infant developments, and histopathological changes were then observed. The results showed that the treatment of HMWCS could decrease body weights and food consumptions, and induce diarrhea, vaginal bleeding, and some other adverse effects in F0 mice. For the emaciation and threatened abortion of pregnant mice, the numbers of live fetuses and early resorption were reduced significantly in HMWCS groups. However, the developments of F1 and F2 mice were not affected, except for lower weights of the body and some organs. In addition, the NOAEL of HMWCS in maternal toxicity was considered to be less than 125 mg/kg, and the NOAEL in developmental toxicity was 125 mg/kg.     

低分子肝素钙在进展型脑血栓治疗中的临床价值观察

目的研究低分子肝素钙在进展型脑血栓治疗中的临床价值。方法选取的研究对象为2015年12月~2016年12月收治的进展型脑血栓患者,将66例患者计算机随机分为两组,各33例。一组患者实施常规治疗(对照组),另一组在此基础上采用低分子肝素钙治疗(观察组)。对比两组患者的神经功能缺损评分、临床总有效率、临床用药总时间、神经功能恢复正常时间、血液学指标以及日常生活活动能力评分。结果观察组进展型脑血栓患者治疗中和治疗后的神经功能缺损评分和日常生活活动能力评分均比对照组患者低(P<0.05),临床总有效率同对照组相比更高(P<0.05),临床用药总时间以及神经功能恢复正常时间少于对照组(P<0.05),血液学指标中除红细胞压积组间对比无明显差别外(P>0.05),观察组患者的其他指标均优于对照组(P<0.05)。结论在进展型脑血栓患者的治疗中采用低分子肝素钙的效果优越,具有较高的临床推广价值。     

低分子肝素明胶复合物及其制剂性质考察

制备了低分子肝素明胶口服制剂 ,考察了复合物及制剂的各种性质 ,由差热分析和红外分析可表明复合物与混合物不同。并进行了初步药效学实验 ,实验表明低分子肝素明胶复合物及制剂经口给药 ,均能明显延长小鼠凝血时间     

低分子壳聚糖季铵盐对小鼠实体瘤及其免疫系统的影响

目的研究低分子壳聚糖季铵盐对小鼠S180 和机体免疫功能的影响。方法采用抑瘤实验、碳粒廓清实验、MTT法观察低分子壳聚糖季铵盐对小鼠实体瘤和免疫系统的影响。结果低分子壳聚糖季铵盐可使荷瘤小鼠的碳粒廓清指数、胸腺指数、脾脏指数升高,并对由ConA、脂多糖诱导体外小鼠T ,B淋巴细胞增殖有明显的兴奋作用;能够抑制小鼠实体瘤的生长。结论低分子壳聚糖季铵盐能够增强机体的免疫功能,并具有抑瘤作用     

小剂量尿激酶与低分子肝素钙治疗不稳定性心绞痛

目的观察小剂量尿激酶+低分子肝素钙治疗不稳定性心绞痛(UAP)的临床疗效。方法将80例UAP患者随机分为尿激酶、低分子肝素钙组(A组)43例,尿激酶10万U溶于100ml生理盐水静脉滴注,连续12d,低分子肝素钙5000U皮下注射,1次/d,共12d;常规治疗组(B组)37例,硝酸甘油10mg溶于5%葡萄糖500ml静脉滴注,共12d,复方丹参20ml溶于5%葡萄糖200ml静脉滴注,共12d。观察两组治疗UAP总有效率及出血等不良反应的发生率,治疗前后测定血小板计数(BPC)、激活全血凝固时间(ACT)、纤维蛋白原定量(FB)。结果两组UAP治疗总有效率分别为88.4%和62.2%(P<0.05),轻微出血发生率两组间及治疗前后BPC、ACT、FB均无显著性差异(P>0.05)。结论小剂量尿激酶+低分子肝素钙治疗UAP疗效显著,且用药安全。