琼脂糖微囊化猪胰岛异种移植治疗糖尿病的实验观察

背景:以往研究表明体外琼脂糖微囊化成猪胰岛具有一定的有效生物活性.但移植到动物体内后的生物活性还有待明确.目的:观察实验性糖尿病大鼠腹腔内移植琼脂糖微囊化成猪胰岛治疗效果.设计,时间及地点:对比观察实验,于2007-12/2008-12在郑州大学中心实验室完成.材料:以琼脂糖作为制备微囊的材料,用相分离方法包被成猪胰岛.方法:①将纯化后未微囊化胰岛及微囊化胰岛分置于RPMI1640培养液培养, 隔日换液.收集培养第1天及第5天培养液上清,检测胰岛素含量.②解剖镜下挑选同一时间微囊的胰岛细胞,分别置于5.6 mmol/L葡萄糖、16.6 mmol/L葡萄糖和10.0 mmol/L茶碱溶液中,做静态孵育下的胰岛素刺激释放试验,放射免疫法测定胰岛素含量.③27只糖尿病大鼠随机分为3组:对照组、未微囊化胰岛移植组、微囊化胰岛移植组,分别注入生理盐水、(0.9～1.6)×103个未微囊化成猪胰岛、(0.8～1.7)×103个微囊化成猪胰岛.主要观察指标:微囊化胰岛培养液中基础胰岛素含量变化,微囊化胰岛对高糖与茶碱刺激的反应性,胰岛移植后糖尿病大鼠的生存期.结果:微囊化胰岛在1个月的培养期间可持续分泌胰岛素.囊内细胞生长良好,微囊没有溶解和破碎.培养2 d的微囊化胰岛对高糖与茶碱刺激有明显反应,胰岛素释放量分别为低糖的1.96倍和2.58倍(P<0.01).移植后7d时,3组血糖分别为(21.61±1.21)mmol/L,(19.11±2.39)mmol/L和(13.67±1.43)mmol/L,微囊化胰岛移植组与前2组相比差异均有显著性意义,且生存期明显长于前2组.结论:琼脂糖微囊化成猪胰岛可存活于糖尿病大鼠体内,并且具有有效生物活性.     

Induction of immune unresponsiveness to concordant islet xenografts by intrahepatic preimmunization and transient immunosuppression.

Streptozotocin-induced, diabetic mice (C57BL/6) were preimmunized by injecting 25 low temperature, cultured Wistar-Furth (WF) rat islets into the portal vein, and the recipients received one injection of mouse and rat antilymphocyte sera. 3 wk later, fresh WF islets were transplanted under the kidney capsule of the preimmunized recipients, and normoglycemia was maintained in all 13 recipients for 60 d. Removal of the grafts at 60 d returned the mice to a diabetic state. Transplants of fresh WF islets under the kidney capsule without pretreatment of the recipients had a mean survival time of 16.5 +/- 2.5 d. These findings demonstrate that immune unresponsiveness can be achieved across a concordant, islet xenograft barrier within 3 wk after intrahepatic preimmunization with a small number of donor rat islets and transient immunosuppression with antilymphocyte sera.     

人嗜铬细胞微囊化处理对大鼠异种移植的免疫隔离作用

背景:课题组前期在建立海藻酸钠-多聚赖氨酸-海藻酸钠微囊包裹活细胞制备技术的基础上,已证明微囊化嗜铬细胞有良好的镇痛效果,而该微囊包被材料的免疫隔离作用尚需明确.目的:观察海藻酸钠-多聚赖氨酸-海藻酸钠微囊化嗜铬细胞移植到大鼠眼前房和足胝部的免疫排斥反应,评价微囊化技术的免疫隔离作用.设计:随机对照动物实验.单位:华中科技大学同济医学院附属同济医院麻醉学教研室.材料:选用雌性 SD大鼠48只,鼠龄3个月,由华中科技大学同济医学院实验动物部提供.实验过程中对动物处置符合动物伦理学标准.实验所用海藻酸钠、多聚赖氨酸为美国Sigma公司产品,微囊发生器为德国赠送.方法:实验于2002-09/2003-09在华中科技大学同济医学院附属同济医院麻醉学实验室完成.①取6名脑死亡健康成人的肾上腺髓质,经分离、消化、培养后,制备成人嗜铬细胞悬液.供者家属对实验知情同意,实验方案通过医院伦理委员会批准.采用海藻酸钠-聚赖氨酸-海藻酸钠法制作空微囊和微囊化细胞.②48只大鼠被随机分为3组:人嗜铬细胞移植组、空微囊移植组、微囊化人嗜铬细胞移植组,每组分眼前房和足胝部两个部位进行移植,每个部位8只.人嗜铬细胞移植组分别将2×1010 L-1细胞悬液注入大鼠右眼前房和左足胝部.空微囊移植组和微囊化人嗜铬细胞组分别吸取空微囊(100个微囊)或ME-HCC(100个微囊,每个微囊包裹400～500个细胞)注入大鼠右眼前房和左足胝部.主要观察指标:于移植术后第7天采用ELISA法测定血清白细胞介素2水平.采用激光散射比浊仪测定血清IgG和IgM水平.移植术后第28天取大鼠右侧眼球及左侧足组织作常规切片,苏木精-伊红染色,40倍光镜下观察组织形态.结果:大鼠48只均进入结果分析.①血清白细胞介素2,IgG,IgM水平:空微囊移植组和微囊化人嗜铬细胞移植组均低于人嗜铬细胞移植组,差异有显著性意义(t=8.544～21.64,P < 0.01).②大鼠眼前房和足胝部组织形态:人嗜铬细胞移植组大鼠的眼前房内和足胝部可见大量淋巴细胞和中性粒细胞浸润.空微囊移植组和微囊化人嗜铬细胞移植组大鼠眼前房和足胝部仅见少量淋巴细胞和中性粒细胞.结论:海藻酸钠-多聚赖氨酸-海藻酸钠微囊化所产生的良好生物相容性及其机械稳定性,使之有效地发挥了免疫排斥隔离作用.     

Parental diabetes in Taiwanese diabetic women with and without previous gestational diabetes

Background    Gestational diabetes mellitus (GDM) is reported to be associated with maternal but not paternal diabetes. This study examined the relative contribution of maternal and paternal diabetes among type 2 diabetic women with and without a GDM history.
Materials and methods    A total of 48 502 type 2 diabetic women from a national sample were interviewed by telephone. Among them, 510 reported a GDM history. Parental diabetes was compared between patients with and without a GDM history considering the confounding effects of age, body mass index, smoking, hypertension, duration of diabetes and insulin use.
Results    Patients with a GDM history were younger in age, had younger age of onset, longer duration of diabetes, slightly lower body mass index, higher prevalence of insulin use and lower prevalence of hypertension, but smoking rates were similar. The percentages of parental diabetes of nil, mother only, father only and both father and mother for those without a GDM history were 76·2, 15·2, 5·8 and 2·8%, respectively; and were 47·8, 26·8, 17·5 and 7·9%, respectively, for those with a GDM history ( P  < 0·001). The adjusted odds ratios for patients with versus without a GDM history for parental diabetes of nil, mother only, father only, and both father and mother were 1·000, 1·210 (0·948–1·544), 1·783 (1·341–2·371) and 2·094 (1·440–3·045), respectively.
Conclusions    Although maternal diabetes is more commonly seen, the disproportionately higher paternal diabetes in patients with a GDM history suggests an important role for paternal diabetes on the development of GDM into type 2 diabetes mellitus.     

Reversal of beta-cell suppression in vitro in pancreatic islets isolated from nonobese diabetic mice during the phase preceding insulin-dependent diabetes mellitus.

Insulin-dependent diabetes mellitus (IDDM) is characterized by a progressive autoimmune destruction of the pancreatic beta-cells. One of the best-suited animal models for IDDM is the nonobese diabetic (NOD) mouse. In this investigation pancreatic islets were isolated from female NOD mice aged 5-7, 8-11, and 12-13 wk and examined immediately (day 0) or after 7 d of culture (day 7). The mice showed a progressive disturbance in glucose tolerance with age, and a correspondingly increased frequency of pancreatic insulitis. Islets isolated from the oldest mice often contained inflammatory cells on day 0, which resulted in an elevated islet DNA content. During culture these islets became depleted of infiltrating cells and the DNA content of the islets decreased on day 7. Islets of the eldest mice failed to respond with insulin secretion to high glucose, whereas a response was observed in the other groups. After culture all groups of islets showed a markedly improved insulin secretion. Islets from the 12-13-wk-old mice displayed a lower glucose oxidation rate at 16.7 mM glucose on day 0 compared with day 7. Islet (pro)insulin and total protein biosynthesis was essentially unaffected. In conclusion, islets obtained from 12-13-wk-old NOD mice exhibit an impaired glucose metabolism, which may explain the suppressed insulin secretion observed immediately after isolation. This inhibition of beta-cell function can be reversed in vitro. Thus, there may be a stage during development of IDDM when beta-cell destruction can be counteracted and beta-cell function restored, provided the immune aggression is arrested.     

Normalization of blood glucose in diabetic rats with phlorizin treatment reverses insulin-resistant glucose transport in adipose cells without restoring glucose transporter gene expression.

Insulin secretion and insulin sensitivity were evaluated in eight clinically stable cirrhotic patients and in 12 controls. OGTT was normal in cirrhotics but plasma insulin response was increased approximately twofold compared with controls. Subjects received a three-step (0.1, 0.5, 1.0 mU/kg.min) euglycemic insulin clamp with indirect calorimetry, [6-3H]-glucose, and [1-14C]-palmitate. During the two highest insulin infusion steps glucose uptake was impaired (3.33 +/- 0.31 vs. 5.06 +/- 0.40 mg/kg.min, P less than 0.01, and 6.09 +/- 0.50 vs. 7.95 +/- 0.52 mg/kg.min, P less than 0.01). Stimulation of glucose oxidation by insulin was normal; in contrast, nonoxidative glucose disposal (i.e., glycogen synthesis) was markedly reduced. Fasting (r = -0.553, P less than 0.01) and glucose-stimulated (r = -0.592, P less than 0.01) plasma insulin concentration correlated inversely with the severity of insulin resistance. Basal hepatic glucose production was normal in cirrhotics and suppressed normally with insulin. In postabsorptive state, plasma FFA conc (933 +/- 42 vs. 711 +/- 44 mumol/liter, P less than 0.01) and FFA turnover (9.08 +/- 1.20 vs. 6.03 +/- 0.53 mumol/kg.min, P less than 0.01) were elevated in cirrhotics despite basal hyperinsulinemia; basal FFA oxidation was similar in cirrhotic and control subjects. With low-dose insulin infusion, plasma FFA oxidation and turnover failed to suppress normally in cirrhotics. During the two higher insulin infusion steps, all parameters of FFA metabolism suppressed normally. In summary, stable cirrhotic patients with normal glucose tolerance exhibit marked insulin resistance secondary to the impaired nonoxidative glucose disposal. Our results suggest that chronic hyperinsulinism may be responsible for the insulin resistance observed in cirrhosis.     

Prevention of diabetes in nonobese diabetic mice by dendritic cell transfer.

The purpose of this study was to determine the effect of dendritic cell (DC) transfers on the incidence of diabetes in female nonobese diabetic (NOD) mice. Groups of 4-wk-old NOD female mice were given a single foot pad of DCs (70-90% purity) isolated from the draining lymph nodes (LN) of the pancreas (PLN), the cervical LNs, or the axillary/inguinal LNs. In addition, other groups of NOD mice received purified spleen DCs, purified PLN T cells (the major contaminating population in DC preparations), or the injection vehicle PBS. All groups were monitored for diabetes for one year. Significant protection from diabetes was observed in NOD mice receiving greater than 1 x 10(4) PLN DCs in comparison to mice receiving other DCs populations, PLN T cells, or PBS (P less than 0.05). The pancreata of NOD mice that received PLN DCs demonstrated significantly lower levels of lymphocytic infiltration in the islets that age-sex matched nondiabetic female NOD control mice (P less than 0.05). LN cells from nondiabetic NOD mice that received PLN DC protected irradiated female recipients from the adoptive transfer of diabetes to a greater degree than LN cells from age and sex matched nondiabetic female NOD mice that did not receive PLN DC transfers at 36 d (P = 0.014) and at 1 yr (P = 0.0015) after transfer. These data suggest that the PLN DC transfers are able to modulate autoimmunity and limit diabetes expression in the NOD mouse. PLN DCs transfers may regulate autoimmunity by the induction of regulatory cells.     

Normalization of high interictal cerebrovascular reactivity in migraine without aura by treatment with flunarizine

BACKGROUND: Modification of migraine-associated cerebrovascular reactivity may provide insight into the mechanism of action of a given therapeutic intervention. METHODS: With transcranial Doppler and a breath-holding index, cerebrovascular reactivity to hypercapnia was evaluated in 20 patients with migraine without aura interictally and in 11 healthy controls. Patients were started on prophylactic treatment with flunarizine 10 mg per day, and measurements were repeated at the end of every month for 3 months. Headache status was evaluated clinically via a headache index. Headache index; breath-holding index; systolic, diastolic, and mean blood flow velocities; and pulsatility index measurements were recorded at every session. RESULTS: The baseline breath-holding index was significantly higher in the migraine group compared to the control group (P =.002). No difference in other parameters was found between the groups. The change in the headache index was significant (P<.001), indicating a beneficial effect from flunarizine. The breath-holding index improved significantly after treatment (P<.001), and the baseline difference in the breath-holding index between the pretreatment migraine group and the control group was no longer evident at 3 months. There was no significant change with treatment in the other transcranial Doppler parameters. CONCLUSIONS: Our finding of unchanged blood flow velocities but normalized cerebrovascular reactivity after treatment suggests that the mechanism of action of flunarizine in migraine does not involve a vasodilatory effect on cerebral vessels. It may be instead that flunarizine modifies cerebrovascular reactivity through its action on centrally located structures that subserve autonomic vascular control.     

Morphine dependence and diabetes. I. The development of morphine dependence in streptozotocin-diabetic rats and spontaneously diabetic C57BL/KsJ mice

Spontaneously diabetic (db/db) and nondiabetic (db/m+, m+/m+) C57BL/KsJ mice were made dependent by a 9-day exposure to increasing doses of morphine-admixed food. Radioimmunoassay for morphine demonstrated that diabetic mice had significantly greater brain accumulations of morphine than nondiabetic littermates after morphine-admixed food. Despite their greater brain levels of morphine, diabetic mice showed significantly fewer behavioral signs of withdrawal after naloxone, and lost significantly less weight at 60 min after naloxone than their nondiabetic littermates. Streptozotocin-diabetic and nondiabetic rats rendered dependent by a 6-day i.p. infusion of morphine had equal brain levels of morphine, but the diabetic rats showed significantly fewer behavioral signs of withdrawal than nondiabetic rats at 24 and 48 hr after the end of the infusion. These results indicate that spontaneously diabetic mice and streptozotocin-diabetic rats were both significantly less physically dependent upon morphine than their respective nondiabetic controls and support our conclusion that the development of physical dependence upon morphine is reduced in experimental models of diabetes.     

Therapy of experimental type 1 diabetes by isolated Sertoli cell xenografts alone

Type I diabetes mellitus is caused by autoimmune destruction of pancreatic β cells, and effective treatment of the disease might require rescuing β cell function in a context of reinstalled immune tolerance. Sertoli cells (SCs) are found in the testes, where their main task is to provide local immunological protection and nourishment to developing germ cells. SCs engraft, self-protect, and coprotect allogeneic and xenogeneic grafts from immune destruction in different experimental settings. SCs have also been successfully implanted into the central nervous system to create a regulatory environment to the surrounding tissue which is trophic and counter-inflammatory. We report that isolated neonatal porcine SC, administered alone in highly biocompatible microcapsules, led to diabetes prevention and reversion in the respective 88 and 81% of overtly diabetic (nonobese diabetic [NOD]) mice, with no need for additional β cell or insulin therapy. The effect was associated with restoration of systemic immune tolerance and detection of functional pancreatic islets that consisted of glucose-responsive and insulin-secreting cells. Curative effects by SC were strictly dependent on efficient tryptophan metabolism in the xenografts, leading to TGF-β–dependent emergence of autoantigen-specific regulatory T cells and recovery of β cell function in the diabetic recipients.A cure for type 1 diabetes in humans will probably require the provision or elicitation of new pancreatic islet β cells in conjunction with reestablishment of immunological tolerance. Sertoli cells (SCs) are normally found in the testes, where they couple trophic effects with prevention of immune damage to developing germ cells. SCs engraft and self-protect when transplanted into allogeneic and xenogeneic environments (Emerich et al., 2003). In different settings, SCs manifest an ability to provide local immunoprotection to cografted tissues, including those from xenogeneic donors (Shamekh et al., 2006). In murine type 1 diabetes, SCs protect cografted allogeneic and xenogeneic islets from immune destruction (Suarez-Pinzon et al., 2000; Yang et al., 2002). Thus, SC might confer immunoprotection for transplanted islets in humans, representing a possible means of overcoming the major obstacle associated with cell therapy. In addition, porcine SC culture supernatants mediate the homologous transdifferentiation in vitro of neonatal pancreatic duct cells into endocrine cells (Basta et al., 2004).SCs can be implanted into the central nervous system to locally deliver molecules with trophic and antiinflammatory effects on the surrounding tissue (Sanberg et al., 1996). When SCs are grafted into an experimental model of Huntington''s disease, the beneficial effects are quite similar to those obtained by systemic treatment with nonsteroidal antiinflammatory drugs (Emerich, 2004). SCs also provide protection in experimental models of Parkinson''s disease and amyotrophic lateral sclerosis (Sanberg et al., 1997; Luca et al., 2007). Although these data do not clarify the underlying mechanisms, they do suggest that the graft of SCs alone may exert beneficial effects on specific tissues through their ability to provide trophic effects and/or modulation of pathogenic inflammation.The nonobese diabetic (NOD) strain of mice has become a prototypic model of autoimmune disease (Delovitch and Singh, 1997; Atkinson and Leiter, 1999). A large proportion of female mice generally dies of type 1 diabetes, reflecting the onset of severe insulitis at ∼4 wk of age and the T cell–mediated destruction of pancreatic β cells. The predisposition of NOD mice to develop autoimmunity is the result of defects in both peripheral and central tolerance mechanisms (Kishimoto and Sprent, 2001). Several abnormalities have been described in those mice, including aberrant APC function (Serreze et al., 1993) and impaired activity of the immunosuppressive enzyme indoleamine 2,3-dioxygenase (IDO; Grohmann et al., 2003a; Fallarino et al., 2004), whose effects are typically linked to the generation and function of regulatory T (T reg) cells in the periphery (Puccetti and Grohmann, 2007).In different experimental settings, immunological reversal of autoimmune diabetes does not require externally provided β cell precursors, suggesting that control of the autoimmune disease at a crucial time in diabetogenesis can result in recovery of β cell function (reversion rates of 30–41%; Chong et al., 2006; Suri et al., 2006). In one such study, the recovered islets from long-term survivors were, indeed, all of host origin, indicating that the diabetic NOD mice actually retain substantial β cell mass, which can be reconditioned to reverse disease upon adjuvant-dependent dampening of autoimmunity (Kodama et al., 2003; Nishio et al., 2006).In the present study, we aimed at revitalizing pancreatic islet β cells in NOD mice by means of the trophic and immunoregulatory effects of neonatal porcine SC administered alone in highly biocompatible alginate microcapsules. In these conditions, the grafted SCs remain viable and functional for remarkably long periods of times (Luca et al., 2007). We obtained evidence that IDO-expressing xenogeneic SC could represent a novel form of cell therapy in NOD mice, combining control of autoimmunity and emergence of T reg cell responses with pancreas regeneration from adult multipotent progenitor cells.     

Structural and functional retinal changes in patients with type 2 diabetes without diabetic retinopathy

ObjectiveThe characteristics of the early changes in preclinical diabetic retinopathy (DR) are poorly known. This study aimed to analyse the changes in the structure and function of the fundus in diabetic patients without diabetic retinopathy (NDR).MethodsThis prospective study enrolled patients with type 2 diabetes and healthy controls from April to December 2020. Retinal sensitivity was measured by microperimetry. The peripapillary retinal nerve fibre layer (p-RNFL) thickness, macular retinal thickness, and retinal volume were measured by optical coherence tomography (OCT). The vessel density (VD) and perfusion density (PD) of the peripapillary area, as well as the foveal avascular zone (FAZ) area, FAZ perimeter, and FAZ circularity, were measured by optical coherence tomographic angiography (OCTA).ResultsA total of 71 cases (100 eyes) were enrolled in the study, including 34 cases (51 eyes) in the NDR group and 37 cases (49 eyes) in the control group. The mean retinal sensitivity was lower in the NDR group than in the control group for all sectors (all p < .001). Compared with controls, the NDR group showed thinner p-RNFL in the T sector (76.24 ± 14.29 vs. 85.47 ± 19.66 µm, p = .035). The NDR group had a thinner retina in the N2 sector (304.55 ± 16.07 vs. 312.02 ± 12.30 µm, p = .010). The PD of DCP was lower in the N2 sector in the NDR group (44.92 ± 11.77 vs. 50.27 ± 6.37%, p = .044). The VD was higher in the NDR group in RPCP-S/N/I, and the PD was higher in the RPCP-S/N (all p < .05). The frequencies of perifoveal capillary drop-out, notched or punched out borders of the superficial FAZ, and loss of smooth contour were all higher in the NDR group (all p < .05).ConclusionThe structure (p-RNFL thickness, VD, and PD) and function (retinal sensitivity) display some changes in diabetic patients even if they had not been found to have DR.

Key messages

1. Decreased retinal sensitivity was observed in diabetic patients before the onset of diabetic retinopathy.
2. Compared with the control group, we found the changes in vessel density or perfusion density in a certain area, whether in SCP, DCP, or RPCP in the NDR group.
3. Before the onset of diabetic retinopathy, the structure and function of the retina in diabetic patients had changed.

     

Choroidal and macular thickness changes in type 1 diabetes mellitus patients without diabetic retinopathy

Objectives: To explore choroidal thickness (ChT) and retinal thickness (RT) changes in patients with type 1 diabetes mellitus (DM).

Methods: Sixty patients with Type 1 DM and 60 age- and sex-matched healthy controls were included in this prospective case–control clinical study. All patients underwent a complete ophthalmological examination. ChT of each participant was measured at the fovea and horizontal nasal and temporal quadrants at 500-µm intervals to 1500 µm from the foveola using spectral-domain optical coherence tomography (SD-OCT). Age, gender, disease duration, serum glycosylated hemoglobin (HbA1c), fasting glucose level, axial length (AL) and refractive error were noted and analyzed.

Results: Mean disease duration, mean HbA1c and mean fasting blood glucose in diabetic patients were 6.1±2.8 years, (8.9±0.9)% and 287.5±69.1 mg/dl, respectively. Age, gender, AL, spherical equivalent differences between the patients and subjects were insignificant (p>0.05). Subfoveal ChT, nasal quadrant ChT measurements, temporal 1500 µm and mean nasal ChT were significantly lower in diabetic patients (p<0.05 for all). Temporal 500 µm and 1000 µm ChT measurements, mean temporal ChT, average ChT, central macular thickness and average macular thickness did not differ significantly between the groups (p>0.05 for all).

Conclusion: This study showed that there is choroidal thinning in young Type 1 diabetic patients with early period of disease duration without diabetic retinopathy nor any other systemic diseases. Choroidal changes in type 1 DM seem to begin at nasal and distal temporal retina. These results need to be verified by larger and longitudinal studies.     

Normalization of insulin sensitivity in type I diabetic subjects by physical training during insulin pump therapy

Seven type I (insulin-dependent) diabetic patients previously treated with continuous subcutaneous insulin infusion therapy participated in a 6-wk training program consisting of cycle ergometer exercise 1 h/day 4 times a week. Six nontraining pump-treated type I diabetic patients and 19 healthy subjects were studied as controls. The training improved maximal aerobic power (VO2 max) by 8% (P less than 0.05). Hemoglobin A1 was in the high normal range before training (8.6 +/- 0.4%) and remained unchanged. The ratio of HDL cholesterol to total cholesterol rose by 16% in the training group (P less than 0.01) but remained unchanged in the sedentary diabetic patients. Mean daily insulin requirements fell by 6% in the training group (P less than 0.01). This reduction occurred in the lunch and dinner boluses whereas the basal infusion rate remained unchanged. Insulin sensitivity as determined by the euglycemic clamp technique was 25-40% lower in the training group (5.24 +/- 0.48 mg/kg/min) and sedentary diabetic group (6.55 +/- 0.82 mg/kg/min) as compared with controls (8.69 +/- 0.77 mg/kg/min, P less than 0.025). After the training, the rate of glucose uptake rose by 60% (P less than 0.001) to 8.48 +/- 0.77 mg/kg/min, which was comparable to that in the controls, but remained unaltered in the sedentary diabetic group. Insulin binding to erythrocytes was comparable in the diabetic and healthy subjects, and remained unchanged. Basal hepatic glucose production was elevated in both groups of diabetic patients (P less than 0.05), whereas the suppression by insulin was normal, and both of these were unaltered by training.(ABSTRACT TRUNCATED AT 250 WORDS)     

Partial regeneration/proliferation of the beta-cells in the islets of Langerhans by Nigella sativa L. in streptozotocin-induced diabetic rats

This experiment was carried out to investigate the effect of N. sativa L. on histopathology of pancreatic beta-cells, and blood insulin and glucose concentrations in streptozotocin-induced diabetic rats. Fifty male Wistar rats (200-250 g) were divided into two experimental groups (diabetics with no treatment and diabetics with N. sativa L. treatment), each containing twenty-five rats. Diabetes was induced in both groups by a single intraperitoneal injection of streptozotocin (STZ) (50 mg/kg). The experimental animals in both groups became diabetic within 24 hours after the administration of STZ. The rats in N. sativa L.-treated group were given the daily intraperitoneal injection of 0.20 ml/kg of N. sativa L. volatile oil for 30 days starting the day after STZ injection. Control rats received only the same amount of normal saline solution. The rats in both groups received the last injection 24 hours before the sacrification and 5 randomly-selected rats in each group were sacrificed before, and the 1, 10, 20 and 30 days after the STZ injection to collect blood and pancreatic tissue samples. The N. sativa L. treatment caused a decrease in the elevated serum glucose, an increase in the lowered serum insulin concentrations and partial regeneration/ proliferation of pancreatic beta-cells in STZ-induced diabetic rats with the elapse of the experiment. It is concluded that the hypoglycaemic action of N. sativa L. could be partly due to amelioration in the beta-cells of pancreatic islets causing an increase in insulin secretion. More studies are needed to demonstrate the exact mechanism of action of N. sativa L. on ameliorated blood glucose concentration in STZ-induced diabetes.     

Impairment of glucose-induced insulin secretion in human pancreatic islets transplanted to diabetic nude mice.

Hyperglycemia-induced beta-cell dysfunction may be an important component in the pathogenesis of non-insulin-dependent diabetes mellitus. However, most available data in this field were obtained from rodent islets. To investigate the relevance of this hypothesis for human beta-cells in vivo, human pancreatic islets were transplanted under the renal capsule of nude mice. Experimental groups were chosen so that grafted islets were exposed to either hyper- or normoglycemia or combinations of these for 4 or 6 wk. Grafts of normoglycemic recipients responded with an increased insulin release to a glucose stimulus during perfusion, whereas grafts of hyperglycemic recipients failed to respond to glucose. The insulin content of the grafts in the latter groups was only 10% of those observed in controls. Recipients initially hyperglycemic (4 wk), followed by 2 wk of normoglycemia regained a normal graft insulin content, but a decreased insulin response to glucose remained. No ultrastructural signs of beta-cell damage were observed, with the exception of increased glycogen deposits in animals hyperglycemic at the time of killing. It is concluded that prolonged exposure to a diabetic environment induces a long-term secretory defect in human beta-cells, which is not dependent on the size of the islet insulin stores.     

血浆总同型半胱氨酸水平与2型糖尿病和糖尿病肾病

目的探讨2型糖尿病(T2DM)和糖尿病肾病(DN)患者血浆总同型半胱氨酸(tHcy)水平、影响因素及与DN之间的关系。方法对诊断T2DM有大量蛋白尿的34例患者(组1),T2DM有微量白蛋白尿的60例患者(组2),T2DM微量白蛋白尿正常的148例患者(组3),尿微量白蛋白正常的非糖尿病对照的140例者(组4)的血浆tHcy及临床基本资料、血、尿相关指标进行调查和检测,并计算内生肌酐清除率(Ccr)和胰岛素抵抗指数(HOMA)。结果各组之间的血浆tHcy水平有显著性差异(P<0.001),组1 tHcy(16.9±5.0μmol/L),组2(13.4±3.7μmol/L),组3(11.8±4.2μmol/L)皆明显高于组4(11.0±6.0μmol/L)。组3、组2、组1的高同型半胱氨酸血症(HHe)发生率依次增高(15.5%,36.4%,58.8%),各组之间呈显著性差异(P<0.001),皆明显高于组4(7.9%)。组4至组1患者血清叶酸、VitB12呈明显下降趋势(P<0.001)。以糖尿病患者组(组1、组2、组3,n=242)lg tHcy为因变量,多元线性回归分析显示年龄、Scr、叶酸、VitB12是血浆lg tHcy的独立影响因素(R=0.613,R2=0.376)。在2型糖尿病患者(组1、组2、组3,n=242)中,以DN为因变量,经二项分类Logistic回归分析显示,血浆tHcy每升高5μmol/L,DN发病的危险率增加2.041倍(OR=2.041,95%CI 1.377~3.024)。结论尿微量白蛋白正常的T2DM患者血浆tHcy水平及HHe发生率明显升高,随DN的发展,血浆tHcy水平及HHe发生率呈梯度升高,各组之间有显著性差异。通过Logistic回归分析显示血浆tHcy水平升高是T2DM肾病的危险因素。提示临床需要关注和干预T2DM患者的高同型半胱氨酸血症。