Liposomal delivery of a phosphodiesterase 3 inhibitor rescues low oxygen-induced ATP release from erythrocytes of humans with type 2 diabetes

ATP release from erythrocytes in response to low oxygen tension requires an increase in cAMP, the level of which is regulated by phosphodiesterase 3 (PDE3). Such release is defective in erythrocytes of humans with type 2 diabetes (DM2). This study tested a hypothesis that direct delivery of the clinically useful PDE3 inhibitor, cilostazol, to erythrocytes of humans with type 2 diabetes using liposomes would restore low-oxygen tension-induced ATP release. Cilostazol was incorporated into liposomes prepared from dimyristoylphosphatidylcholine (DMPC). Liposome-delivery of cilostazol restored ATP release from DM2 erythrocytes to levels which were not different from that released from non-cilostazol treated healthy erythrocytes under the same conditions. There were no observed adverse effects of the liposomes on either healthy or DM2 erythrocytes. The directed liposomal delivery of PDE inhibitors to erythrocytes may help prevent or slow the development of peripheral vascular disease in individuals with DM2 by restoring an important physiological controller of microvascular perfusion while minimizing side effects associated with systemic delivery of some of these inhibitors.     

Streptococcus pneumoniae type 3 encodes a protein highly similar to the human glutamate decarboxylase (GAD65)

Abstract A 2.5-kb Sca I fragment of the type 3 pneumococcal strain 406 DNA containing a 1425-nucleotide open reading frame ( gadA ) and encoding a 475-amino acid protein ( M _rmr 54427) was characterised. The gene gadA was expressed in Salmonella typhimurium . Pulsed-field gel electrophoresis and Southern blotting analysis of DNAs prepared from several pneumococcal serotypes showed that only those clinical isolates belonging to serotype 3 harbour the gadA gene. Sequence comparison of GadA with proteins included in the data banks revealed the highest similarity with human glutamate decarboxylase (GAD₆₅) (59% similarity, 28% identity). Auto-antibodies to GAD₆₅ have been associated with the onset of insulin-dependent diabetes mellitus. Interestingly, several epitopes of GAD₆₅ that have been identified as immunodominant are particularly well conserved in the pneumococcal GadA.     

Recruitment of Nox4 to a Plasma Membrane Scaffold Is Required for Localized Reactive Oxygen Species Generation and Sustained Src Activation in Response to Insulin-like Growth Factor-I

Nox4-derived ROS is increased in response to hyperglycemia and is required for IGF-I-stimulated Src activation. This study was undertaken to determine the mechanism by which Nox4 mediates sustained Src activation. IGF-I stimulated sustained Src activation, which occurred primarily on the SHPS-1 scaffold protein. In vitro oxidation experiments indicated that Nox4-derived ROS was able to oxidize Src when they are in close proximity, and Src oxidation leads to its activation. Therefore we hypothesized that Nox4 recruitment to the plasma membrane scaffold SHPS-1 allowed localized ROS generation to mediate sustained Src oxidation and activation. To determine the mechanism of Nox4 recruitment, we analyzed the role of Grb2, a component of the SHPS-1 signaling complex. We determined that Nox4 Tyr-491 was phosphorylated after IGF-I stimulation and was responsible for Nox4 binding to the SH2 domain of Grb2. Overexpression of a Nox4 mutant, Y491F, prevented Nox4/Grb2 association. Importantly, it also prevented Nox4 recruitment to SHPS-1. The role of Grb2 was confirmed using a Pyk2 Y881F mutant, which blocked Grb2 recruitment to SHPS-1. Cells expressing this mutant had impaired Nox4 recruitment to SHPS-1. IGF-I-stimulated downstream signaling and biological actions were also significantly impaired in Nox4 Y491F-overexpressing cells. Disruption of Nox4 recruitment to SHPS-1 in aorta from diabetic mice inhibited IGF-I-stimulated Src oxidation and activation as well as cell proliferation. These findings provide insight into the mechanism by which localized Nox4-derived ROS regulates the sustained activity of a tyrosine kinase that is critical for mediating signal transduction and biological actions.     

HPLC study on Fenton-reaction initiated oxidation of salicylic acid. Biological relevance of the reaction in intestinal biotransformation of salicylic acid

Abstract

Fenton-reaction initiated in vitro oxidation and in vivo oxidative biotransformation of salicylic acid was investigated by HPLC-UV-Vis method. By means of the developed high performance liquid chromatography (HPLC) method salicylic acid, catechol, and all the possible monohydroxylated derivatives of salicylic acid can be separated. Fenton oxidations were performed in acidic medium (pH 3.0) with two reagent molar ratios: (1) salicylic acid: iron: hydrogen peroxide 1:3:1 and (2) 1:0.3:1. The incubation samples were analysed at different time points of the reactions. The biological effect of elevated reactive oxygen species concentration on the intestinal metabolism of salicylic acid was investigated by an experimental diabetic rat model. HPLC-MS analysis of the in vitro samples revealed presence of 2,3- and 2,5-dihydroxybenzoic acids. The results give evidence for nonenzyme catalysed intestinal hydroxylation of xenobiotics.     

Circadian Rhythm of Blood Pressure Challenges Office Values as the “Gold Standard” in the Diagnosis of Gestational Hypertension

Despite poor sensitivity and specificity, office blood pressure (BP) determinations are still the “gold standard” for diagnosing gestational hypertension. This prospective blind study evaluates the prognostic value of office values as compared with ambulatory monitoring in pregnancy. We analyzed 2175 BP series systematically sampled from 355 non-preeclamptic pregnant women for 48 h every 4 wks from the first hospital visit until delivery. Women were divided for comparative purposes into three groups: “detected” gestational hypertension, defined on the basis of casual clinical BP>140/90 mm Hg after 20 wks of gestation and hyperbaric index (area of BP excess above the upper limit of a time-specified tolerance interval adjusted for the circadian pattern of the reference population) consistently above the threshold for diagnosing hypertension in pregnancy; “undetected” gestational hypertension, women with office BP<140/90 mm Hg but hyperbaric index consistently above the threshold for diagnosis; and normotension, women with both office values and hyperbaric index below the respective thresholds for diagnosis. Small and insignificant differences in the 24 h mean BP between “detected” and “undetected” gestational hypertension is observed in all trimesters, in contrast with highly significant differences between these two groups and normotensive pregnancies. Normotensive women are characterized by highly significant lesser incidence by 60% in preterm delivery, 70% in intrauterine growth retardation, and 50% in delivery by cesarean section (P<0.001) compared with women with “detected” and “undetected” gestational hypertension (P>0.715). In pregnancy, the hyperbaric index is markedly superior to office BP measurements for diagnosis of what should be truly considered gestational hypertension, and for prediction of the outcome of pregnancy.     

Views and opinion on BDNF as a target for diabetic cognitive dysfunction

Type 2 diabetes mellitus (T2DM) is a known cause of cognitive dysfunction and involves increased risk of dementia. Brain-derived neurotrophic factor (BDNF) is a member of neurotrophic family of nerve growth factors, a key protein in promoting memory, growth and survival of neurons. BDNF is recognized as a metabotrophic factor, a molecule that is involved in Alzheimer’s disease (AD) as well as in other neurological disorders. It provides cellular and local regulatory mechanisms for mediating synaptic plasticity. Impaired BDNF signaling can compromise many aspects of brain functions. Studies investigating the relationship between diabetes and BDNF in adults demonstrate that BDNF levels are decreased in T2DM and are regulated in response to plasma levels of glucose. BDNF could serve as biomarker in predicting the development of obesity and T2DM. Thirty-two cavities were predicted to locate the active sites of BDNF for the ligands to bind. The shape of the site was identified by extracting the cavity volume surfaces enclosing regions with highest probability. Different ligands can be chosen for interaction of active sites of BDNF and can be targeted for drug discovery. This review focuses on computational exploitation selectively to deliver BDNF as a drug to appropriate hypothalamic neurons, which can serve as a novel approach in diabetic encephalopathy treatment.     

Electrophysiological evidence for the autoregulation of β-cell secretion by insulin

Electrophysiological studies of cultured rat pancreatic β-cells using intracellular microelectrodes show that exogenous insulin over the range of 0.1–10.0 μg/ml inhibits the electrical activity due to 27.8 mM glucose in a dose-related manner. This inhibitory effect is manifested by a mean increase of the membrane potential from about ?20 to ?30 mV and inhibition of the manner of cells impaled showing spike activity from 60 to less than 10%. The inhibitory influence of insulin is rapid occuring within 5 min for the highest level used. The results provide evidence for a negative feedback role of insulin in regulating its own release.     

高脂喂养联合链脲佐菌素注射的糖尿病大鼠模型特征

目的观察高脂喂养联合低剂量STZ注射的SpragueDawley(SD)大鼠2型糖尿病模型的代谢特征、病理学以及胰岛分子生物学变化。方法4周龄雄性SD大鼠36只随机分为三组(1)正常对照组(Control)9只,普通饲料喂养。(2)高脂组(HighFatchow,HE)9只,高脂饲料喂养,为普通饲料中添加20%脂肪(猪油和蛋黄粉各50%)和20%蔗糖。(3)糖尿病组(DM)18只。喂养4周后腹腔注射STZ(40mg/kg)。所有大鼠做灌胃葡萄糖耐量(OGTT)试验。放免法测定血清胰岛素,免疫组化染色观察胰岛β细胞的形态学特点,彩色图像分析系统测定胰岛素表达量,RT-PCR测定胰腺β细胞胰岛素mRNA表达水平。结果糖尿病大鼠空腹血糖(FBG)、胰岛素水平(FINS)显著高于Control组和HE组大鼠(P<0.01),空腹血清甘油三酯(TG)和游离脂肪酸(FFA)水平显著高于Control组(P<0.05);胰岛β细胞吸光度(A)显著低于高脂组大鼠(P<0.05),降低11.6%。胰岛素免疫反应阳性区占胰岛百分比显著低于Control组和HE组,分别下降31.9%(P<0.05)和43.1%(P<0.01)。胰岛素mRNA表达水平显著低于HE组(P<0.05)。STZ注射后48h(基线值)大鼠FBG水平的分布情况为A组(FBG<10.0mmol/L)占7/18;B组(FBG10~19.9mmol/L)占5/18;C组(FBG≥20mmol/L)占6/18。STZ注射后9d的OGTT结果与基线值相比,B组OGTT值总体变化最小,A组FBG的变异最大,达到25%。结论高脂喂养联合低剂量STZ注射的糖尿病大鼠模型模拟2型糖尿病发生的主要病理生理过程,具有高血糖、高胰岛素血症以及血脂异常等基本特征。     

实验恒河猴糖尿病动物模型建立及视网膜并发症的研究

[目的]糖尿病是由于多种因素和遗传因素导致体内胰岛素相对或绝对分泌不足,而引起的代谢性内分泌疾病,它以血糖、尿糖升高为特点,起病隐蔽,通过并发症使人致残致死,是继心血管、癌症之后的第三大致死性疾病,很可能成为21世纪人类的“第一杀手”(1,2)。本文采用人工诱导的方法,建立恒河猴糖尿病动物模型,研究糖尿病疾病的发展和及其并发症的发生、发展规律和防治措施,同时对于治疗糖尿病新药的安全性评价和药物疗效的观察具有广阔的运用前景。[方法]选用成熟的、健康的、雄性恒河猴9只,随机分成三个组,其中高剂量组(60mg/kg)1只,中剂量组(45m…     

母牛分支杆菌菌苗治疗糖尿病合并初治肺结核的临床分析

目的 探讨母牛分支杆菌菌苗（简称微卡）治疗糖尿病合并肺结核的疗效。方法 同期选取40例糖尿病合并肺结核初治患者,随机分为A、B组。A组以常规抗痨治疗（2HRZE／4HR）,B组在常规抗痨治疗的基础上加用微卡治疗2月。结果 B组结核病灶消散吸收、空洞完全或部分闭合、痰结核菌阴转速度均明显快于A组（P〈0．05）,且不良反应少见。结论 微卡可用作糖尿病合并肺结核的免疫治疗。