胰岛素治疗对血浆抵抗素水平的影响

经ELISA方法测得的空腹血浆抵抗素水平，2型糖尿病患者显著高于正常对照组（P〈0．05）；而在有和无糖尿病微血管病患者之间，不存在明显差异（P〉0．05）。经胰岛素治疗，血抵抗素水平明显下降。     

肌少性肥胖与1型糖尿病：现状与展望

肥胖具有高度异质性, 其中肌少性肥胖与代谢紊乱的关系逐渐被关注。肌少症以及肥胖在1型糖尿病中均不少见, 因此1型糖尿病是肌少性肥胖的潜在高危人群。肌少性肥胖与1型糖尿病胰岛素抵抗及心脏代谢紊乱、糖尿病大血管及微血管并发症风险增加显著相关。探讨肌少性肥胖与1型糖尿病间的相互影响及其机制, 对于指导1型糖尿病的精准治疗具有重要意义。     

糖尿病骨骼肌病变

骨骼肌是糖尿病损害的靶组织，肌组织中的氧化型纤维易受糖尿病损害。糖尿病肌病光镜下主要表现为肌纤维的萎缩，呈失神经性、继发性肌病改变。引起肌病的因素包括糖尿病微血管病变、代谢紊乱和糖尿病神经病变，其中神经病变是营养神经的微血管发生炎症的结果，一些针对性措施已初步显示其防治肌病的效果。肌肉病变将使外周胰岛素抵抗加重。     

亚甲基四氢叶酸还原酶基因多态性与糖尿病微血管并发症相关性研究

目的：探讨亚甲基四氢叶酸还原酶(MTHFR)基因多态性与中国人2型糖尿病微血管并发症的关系。方法：运用PCR—RFLP检测263例中国人(206例为2型糖尿病，其中148例合并肾病或视网膜病变，57例为正常对照组)MTHFR基因C677T位碱其突变，比较各组间等位基因频率和基因型频率。结果：(1)同时合并肾病和视网膜病变的2型糖尿病组与无微血管并发症的2型糖尿病组及正常对照组相比，TT基因型频率显著增加，突变等位基因T频率也明显升高。(2)2型糖尿病合并肾病组TT基因型频率及T等位基因频率明显高于不伴有肾病的2型糖尿病组及正常对照组。(3)2型糖尿病合并视网膜病组与无视网膜病的2型糖尿病及正常对照组相比，TT基因型频率及T等位基因频率明显升高。结论：MTHFR基因C677T碱基突变是促进中国人2型糖尿病患者并发微血管并发症的危险因子，突变T等位基因是糖尿病微血管并发症的易感基因。     

1型糖尿病树鼩骨骼肌病变及其发病机制

目的探讨1型糖尿病(T1DM)树鼩骨骼肌病变的发病机制。方法正常对照组(A组,n=8);STZ糖尿病成模组9只(B组),糖尿病未成模组5只(C组)。在光镜和透射电镜下观察股二头肌形态学变化,以免疫组化法检测肌组织中细胞凋亡相关分子Bcl2、Fas、FasL、caspase1和caspase3的表达。结果B组肌纤维普遍萎缩,肌纤维横截面积明显小于A组(2.49±0.47μm2vs3.79±0.40μm2,P<0.05)电镜下B组肌组织呈灶性肌丝溶解,肌质膜呈锯齿状突起,部分线粒体嵴断裂、基质溶解或空泡化。肌膜下线粒体密集成群、排列紊乱和形态异常。肌细胞核异染色质增多并呈块状边集。肌组织微血管内皮伸出许多伪足,内皮增厚、管腔狭窄。微血管基底膜无明显增厚。B组肌组织对Bcl2、Fas/FasL和caspase3均呈阳性表达,A组和C组仅对FasL呈弱阳性表达。结论骨骼肌纤维普遍性萎缩、灶性肌丝溶解、肌质膜异常突起和线粒体损伤是T1DM树鼩骨骼肌病变的主要特征,骨骼肌组织中细胞凋亡通路激活可能是糖尿病肌病的重要原因。     

糖尿病骨骼肌病变

骨骼肌是糖尿病损害的靶组织 ,肌组织中的氧化型纤维易受糖尿病损害。糖尿病肌病光镜下主要表现为肌纤维的萎缩 ,呈失神经性、继发性肌病改变。引起肌病的因素包括糖尿病微血管病变、代谢紊乱和糖尿病神经病变 ,其中神经病变是营养神经的微血管发生炎症的结果 ,一些针对性措施已初步显示其防治肌病的效果。肌肉病变将使外周胰岛素抵抗加重     

2型糖尿病微血管病变与血管内皮功能及血压的关系

目的 探讨2型糖尿病患者并发微血管病变与血管内皮功能及血压的相关性。方法 选取2型糖尿病患者92例，根据是否并发微血管病变分为单纯2型糖尿病组（对照组）45例和2型糖尿病合并微血管病变组（观察组）47例。测定两组血管循环内皮细胞（CEC）数量和血清内皮素-1(ET-1)水平、肱动脉血流介导性舒张率（FMD）及平均动脉压（MAP）。观察组给予苯磺酸左旋氨氯地平片治疗24周，比较治疗前后患者CEC、ET-1、MAP及FMD变化。采用Pearson相关分析法分析微血管病变指标与内皮功能及血压的相关性。结果 观察组CEC、ET-1及MAP均高于对照组，FMD低于对照组（P均<0.05）；观察组给予苯磺酸左旋氨氯地平片治疗24周后，患者CEC、ET-1及MAP水平下降，FMD水平上升（P均<0.05）。CEC、ET-1与FMD呈负相关（r分别为-0.413、-0.486,P均<0.05），与MAP呈正相关（r分别为0.507、0.516,P均<0.05）。结论 血管内皮功能受损及血压升高与2型糖尿病并发微血管病变存在明显的相关性，二者共同参与2型糖尿病患者并发微血管病变的...     

微血管并发症与2型糖尿病患者骨质疏松的关系

糖尿病性骨质疏松对患者生活、工作及预后产生重大影响,是2型糖尿病研究的热点,与患者微血管病变如糖尿病视网膜病变、糖尿病肾病、糖尿病周围神经病变有密切的关系。本文就2型糖尿病微血管并发症与患者骨质疏松之间的关系进行综述。     

糖尿病微血管病对骨密度及骨钙素的影响

为探讨糖尿病微血管病对骨密度及骨钙素的影响，选择2型糖尿病患者60例，按其是否合并糖尿病微血管病（眼病、肾病、神经病变）分为两组，合并微血管病（1组）33例，不合并微血管病（2组）27例。用生化法测定两组的空腹血糖（FBG）、果糖胺（GSP）、血清总碱性磷酶（TALP）及血钙（Ca^2 ），RIA法测定骨钙素（BGP），DEXA法测定腰椎和髋部骨密度（BMD）；按其身同、体重计算体重指数（BMI）。结果：两组BMI、GSP、FBG、TALP及Ca^2 均未见明显差异；1组血清BGP水平明显低于2组，有显著性差异；1组第2－4腰椎（L2－4）、股骨颈、Ward′s三角区及股骨大转子的BMD均低于2组，差异有显著性。认为糖尿病微血管变可能降低骨形成，加重骨质疏松，使腰椎和髋部BMD明显降低。     

腺苷对心肌细胞的电生理作用及机制探讨

采用微电极技术及膜片钳全细胞记录方式，研究腺苷对豚鼠心肌细胞的电生理作用及其机制。结果表明：腺苷可明显缩短心房肌及房室结区细胞动作电位时程，降低房室结区细胞动作电位振幅、零相最大去极化速率，膜片钳上证明此为腺苷加强延迟整流性钾通道电流和抑制Ｌ型钙通道电流所致。对心室肌细胞无此明显的作用，但应用异丙肾上腺素后证明腺苷能拮抗β１受体的作用。腺苷的作用能被选择性腺苷Ａ１受体阻断剂８－环戊基－１，３－二丙基黄嘌呤消除，提示腺苷对心肌细胞的作用由Ａ１受体介导。本研究也探讨了腺苷对心房肌和心室肌作用区别的可能原因，以及心房肌和心室肌对异丙肾上腺素合用腺苷时反应不同的可能机制。     

Altered skeletal muscle fiber composition and size precede whole-body insulin resistance in young men with low birth weight

CONTEXT: Low birth weight (LBW), a surrogate marker of an adverse fetal milieu, is linked to muscle insulin resistance, impaired insulin-stimulated glycolysis, and future risk of type 2 diabetes. Skeletal muscle mass, fiber composition, and capillary density are important determinants of muscle function and metabolism, and alterations have been implicated in the pathogenesis of insulin resistance. OBJECTIVE: The aim of this study was to investigate whether an adverse fetal environment (LBW) induces permanent changes in skeletal muscle morphology, which may contribute to the dysmetabolic phenotype associated with LBW. DESIGN AND SUBJECTS: Vastus lateralis muscle was obtained by percutaneous biopsy from 20 healthy 19-yr-old men with birth weights at 10th percentile or lower for gestational age (LBW) and 20 normal birth weight controls, matched for body fat, physical fitness, and whole-body glucose disposal. Myofibrillar ATPase staining was used to classify muscle fibers as type I, IIa, and IIx (formerly type IIb), and double immunostaining was performed to stain capillaries (LBW, n=8; normal birth weight, n=12). RESULTS: LBW was associated with increased proportion of type IIx fibers (+66%; P=0.03), at the expense of decreased type IIa fibers (-22%; P=0.003). No significant change was observed in proportion of type I fibers (+16%; P=0.11). In addition, mean area of type IIa fibers was increased (+29%; P=0.01) and tended to be increased for type I fibers as well (+17%; P=0.08). Capillary density was not significantly different between groups. CONCLUSION: Alterations in fiber composition and size may contribute to development of type 2 diabetes in individuals with LBW.     

Histochemical characteristics of soleus muscle in angiotensin-converting enzyme gene knockout mice.

We examined the histochemical characteristics of soleus muscle in the angiotensin-converting enzyme (ACE) gene (Ace in mice, ACE in humans) knockout mice. Serial sections of soleus muscle of wild-type (Ace+/+, n=20) and heterozygous mutant (Ace+/-, n=24) mice were stained for myosin adenosine triphosphatase activity to identify different muscle fiber types. Capillaries were visualized by amylase-periodic acid-Schiff staining. ACE activity in the serum and gastrocnemius muscle was higher in male mice than in female mice. Female and male Ace+/- mice had markedly lower ACE activity in the serum and the gastrocnemius muscle than did female and male Ace+/+ mice, respectively. In both male and female mice, the composition of fiber types (type I and IIa) did not differ significantly between Ace+/+ and Ace+/- mice. There was no significant gender difference in capillary density. Ace+/- mice had significantly more capillaries around type IIa fibers (5.44 +/- 0.18 vs. 5.01 +/- 0.13, p<0.05) than Ace+/+ mice. The differences in the number of capillaries around type I fibers and in the number of capillaries around per fiber (capillary:fiber ratio) between Ace+/- and Ace+/+ mice were not significant (p<0.1). There was no significant difference in the mean cross-sectional area occupied by one capillary and the number of capillaries per fiber area between Ace+/+ and Ace+/- mice. In conclusion, knockout of the Ace gene in mice increased capillary density, as expressed by the mean number of capillaries around type IIa fibers. This finding suggests a possible mechanism for the cardioprotective effects of ACE inhibitors.     

Arteriolization of capillaries and FGF-2 upregulation in skeletal muscles of patients with chronic peripheral arterial disease

OBJECTIVE: Microvascular changes in ischemic skeletal muscle are described derived from patients with long-lasting peripheral arterial disease (PAD). METHODS: Skeletal muscles from the lower limb of 17 patients (obtained after amputation) with chronic PAD and 4 asymptomatic controls (obtained from biopsies after bypass surgery) were evaluated by electron microscopy and immunohistochemistry. RESULTS: The capillaries in skeletal muscles of PAD patients were surrounded by a more than 1 microm-thick coat, which was positively stained for basement membrane pericapillary coat collagen type IV. Thickness of the coat correlated with presence of PAD (p < .0001), and less strongly with diabetes mellitus (p = .023) and age of patients (p = .019). The majority of the capillaries in skeletal muscles of PAD patients (71.1 +/- 15.3%) were covered with cells positive for smooth muscle cell actin (sma) as compared to samples from asymptomatic controls (22.8% +/- 9.6%; p < .0001) suggesting advanced arteriolization. Semiquantitative analysis revealed that patients with PAD demonstrate a higher expression of FGF-2 in capillary endothelial cells (67.8 +/- 17.5%) as compared to controls (10.2 +/- 8.4%; p < .0001), whereas VEGF immunoreactivity was only occasionally present in extravascular cells. CONCLUSION: Thickened collagen type IV-positive basement membranes in combination with a significant increase in sma-coverage indicate arteriolization of capillaries characteristic for chronic PAD, what may be related to high FGF-2 expression in capillary endothelial cells.     

Ceramide content is higher in type I compared to type II fibers in obesity and type 2 diabetes mellitus

This study investigated fiber-type-specific muscle ceramide content in obese subjects and type 2 diabetes patients. Two substudies, one which compared type 2 diabetes patients to both lean- and obese BMI-matched subjects and the other study which compared lean body–matched post-obese, obese, and control subjects, were performed. A fasting blood sample was obtained and plasma insulin and glucose determined. A muscle biopsy was obtained from deltoideus and vastus lateralis, and fiber-type ceramide content was determined by fluorescence immunohistochemistry. Insulin sensitivity estimated by Quicki index was higher in lean compared to type 2 diabetes patients and obese controls. Also in control and post-obese subjects, a higher insulin sensitivity was observed compared to obese subjects. Ceramide content was consistently higher in type I than in type II muscle fibers and higher in deltoideus than vastus lateralis across all groups. No significant differences between groups were observed in ceramide content in either of the two substudies. In human skeletal muscle, ceramide content was higher in type I than in type II fibers in patients with type 2 diabetes and in obese subjects, but overall ceramide muscle fiber content was not different compared to controls.     

Growth of arterioles precedes that of capillaries in stretch-induced angiogenesis in skeletal muscle.

Arteriolar growth accompanying capillary angiogenesis has been linked with hemodynamic factors resulting from increased blood flow. Here we describe the growth of arterioles occurring in rat skeletal muscles stretched by an overload due to the removal of agonist muscles, where blood flow was not increased, and we provide morphological evidence for the type of cells involved in this growth. Rat extensor digitorum longus (EDL) and extensor hallucis proprius (EHP) were overloaded by unilateral extirpation of their agonist, tibialis anterior. EDL muscles were taken for immunohistochemistry in cryostat sections to mark endothelial cells (Griffonia simplicifolia I, GSI lectin), smooth muscle cells and pericytes (alpha smooth muscle actin, alphaSMA), and "mature" arterioles (smooth muscle myosin heavy chains). EHP muscles were used for corresponding evaluation by confocal and electron microscopy. The number of capillaries surrounding muscle fibers was not significantly different after 1 week of stretch but was higher after 2 weeks (5.15 +/- 0.2 vs 4.3 +/- 0.2 in controls, P < 0.05). Similarly, capillary density (CD) and capillary/fiber ratio (C/F) gradually increased (CD 778 +/- 86 at 2 weeks vs 593 +/- 35 mm(-2) in controls, C/F 2.07 +/- 0.13 vs 1.38 +/- 0.06, respectively). In contrast, the number of alphaSMA-positive vessels around fibers increased after 1 week (2.16 +/- 0.09 vs 0.25 +/- 0.02 in controls) and was lower after 2 weeks (1.42 +/- 0.24, P < 0.05, vs 1 week). Arteriolar density was higher at 1 (110.9 +/- 7.5 mm(-2)) and 2 weeks (70.7 +/- 12.1) with respect to controls (31.0 +/- 1.6 mm(-2)). The increased density was greater in alphaSMA-positive vessels <10 microm in diameter (controls 18.0 +/- 1.04, 1 week 77.2 +/- 4.5, 2 wk 42.2 +/- 9.0 mm(-2)) than in vessels >10 microm (13.0 +/- 0.8, 33.7 +/- 4.0, 29.5 +/- 4.7 mm(-2)). Electron microscopy showed "activated" (TEM fine structure) and proliferating (immunogold labeling for BrdU) fibroblasts in the vicinity of capillaries, some of which were embedded in the capillary basement membrane, consistent with a transformation into pericytes and possibly later smooth muscle cells. Confocal microscopy indicated that some mesenchymal cells became GSI positive and formed extended processes which contacted capillaries via tapered endings. Growth of arterioles in stretched muscles appears to involve proliferation of fibroblasts, which may migrate toward capillaries and precedes any apparent increase in capillarization.     

Decreased skeletal muscle capillary density is related to higher serum levels of low-density lipoprotein cholesterol and apolipoprotein B in men.

The relationships between skeletal muscle morphology, particularly muscle fiber capillary density, and serum lipid profiles were evaluated in 25 non-obese men aged 18 to 36 years (body mass index [BMI], 22.7 +/- 2.5 kg/m2; body fat, 13.6% +/- 4.0%, maximal oxygen uptake [VO2max], 46.2 < or = 6.3 mL/kg/min). Skeletal muscle samples were taken from the vastus lateralis using the needle-biopsy method. The fiber types (I, IIa, and IIx) and their percent distribution, the indices of capillary density, and the diffusion index expressed as the cross-sectional area occupied by one capillary were determined. Blood samples were drawn from the antecubital vein after a 12-hour fast. Based on Pearson's correlation analysis, the number of capillaries around type IIx fiber correlated inversely with the serum level of low-density lipoprotein cholesterol ([LDL-C] r = -.50, P < .05). The number of capillaries per fiber (cap/fiber ratio), number of capillaries per area (cap/mm2), and capillaries around each fiber type correlated inversely with the serum level of apolipoprotein B ([apo B] r = -.40 to -.54, P < .05 to .01). Further, the diffusion index for each fiber type correlated positively with LDL-C and apo B (r = .42 to .50, P < .05 to .01). Among 14 subjects in whom high-density lipoprotein cholesterol (HDL-C) subfractions were analyzed, a positive correlation was found between cap/mm2 and HDL2-C (r = .64, P < .05). Partial correlation analysis showed that these correlations either remain or improve after adjusting for age, VO2max, and body fatness. These results indicate that skeletal muscle capillary density and diffusion capacity are related to lipid and apolipoprotein concentrations for both type I and type II fibers.     

Absence of mast cells in diabetic retinopathy

The vascular beds of femoral biceps, soleus, and medial gastrocnemius of the rat were perfused with India ink to outline the capillary network. Histologic cross sections were stained with picric acid and basic fuchsin. By this method, the muscle fiber nuclei appeared red and could be clearly distinguished from the darker-stained capillary profiles. A specific anatomic relationship between capillaries and muscle fiber nuclei was tested against a random orientation by an analysis of independence. Systematic sampling was performed by positioning the center of an eyepiece reference circle on the uppermost point of each fiber profile. The frequencies of the four combinations (fiber nuclei and/or capillaries or neither) found within each test circle were recorded and stored in 2 × 2 contingency tables. The Z test of independence revealed a highly significant relationship between capillaries and fiber nuclei in all muscles examined. The nonrandom nucleus-related location of capillaries around muscle fibers was even more evident after pooling the individual muscle data in a single table (P ? 0.00001). These findings suggested a chemotactic attraction of capillaries by the muscle fiber nuclei. This observation is supported by the high concentration of cytoplasmic organelles present in nuclear regions of skeletal muscle fibers, that is well documented in the literature. These organelles may be responsible for the production and local secretion of chemotactic factors “to attract” capillaries, and hence provide for their characteristic orientation and distribution in muscle.     

Interleukin-1alpha expression in capillaries and major histocompatibility complex class I expression in type II muscle fibers from polymyositis and dermatomyositis patients: important pathogenic features independent of inflammatory cell clusters in muscle tissue

OBJECTIVE: To address the hypothesis that endothelial cells and/or muscle fibers are primary targets in the disease process by analysis of muscle tissue from patients with polymyositis (PM) and dermatomyositis (DM). METHODS: We included patients with laboratory signs and clinical symptoms typical of myositis, but without detectable infiltration of clusters of inflammatory cells in their muscle biopsy samples. An immunohistochemical technique was applied to identify CD3, CD68, lymphocyte function-associated antigen 1alpha, CD11b, very late activation antigen 4, endothelium 4, interleukin-1alpha (IL-1alpha), intercellular adhesion molecule 1, vascular cell adhesion molecule 1, IgG, IgM, IgA, and HLA-A/B/C in muscle tissue. Fiber type was defined by ATPase staining. RESULTS: IL-1alpha expression was detected in endothelial cells of capillaries to a greater extent in patients than in controls, and class I major histocompatibility complex (MHC) expression was significantly increased in muscle fibers. We also observed that class I MHC expression was mainly confined to type II muscle fibers. CONCLUSION: Our findings imply that defined molecular changes of blood vessels and muscle fibers are both independent of adjacent inflammatory infiltrates and could thus be primary events in the development of myositis. Moreover, both IL-1alpha and class I MHC molecules might be important for the development of clinical symptoms in PM and DM patients.     

Hypoxia-induced acute changes in capillary and fiber density and capillary red cell distribution in the rat heart

The influence of acute hypoxia (respiration gas 12%, 10%, and 8% O2 and asphyxia, respectively) on 1) the density of perfused capillaries and muscle fibers, and 2) the capillary red cell distribution was investigated in the left heart of anesthetized rats. To observe capillaries and fibers, fluorescein isothiocyanate-labeled (FITC)-gamma-globulin and lissamine-rhodamine-B200-labeled (RB200) myoglobin were injected intravenously as labels of the perfused intravasal and the extracellular space, respectively. The hypoxic conditions were induced subsequently and maintained for 3 minutes. After this period the heart was rapidly frozen for histological demonstration of the dyes. Ventilation with 12% or 10% O2 did not induce any changes in the density of perfused capillaries; however, 8% O2 in respiration gas did lead to a significant increase (capillaries/mm2: subepicardium, 4,180, controls, 3,620; subendocardium, 3,930, controls, 3,240). A similar increase was found in the asphyxia group (capillaries/mm2: subepicardium, 4,170; subendocardium, 3,700). The increases in the density of perfused capillaries were paralleled by rises in fiber density. This leads to the conclusion that the changes in capillary counts were caused by fiber elongation with a resultant decrease in intercapillary distances. This assumption was supported by observations that there were no signs of changes in ventricular segment length during respiration of 12% or 10% O2 but that an increase did occur with 8% oxygen and with asphyxia. Densities of perfused capillaries exactly coincided with anatomical densities (demonstrated by additional labeling of capillary basement membranes with isolectin B4) in normoxic and asphyctic hearts. The distribution of red cells in the capillaries, determined in histological sections, did not differ appreciably under hypoxia due to reduced O2 in respiration air (12%) or asphyxia. The results obtained indicate that 1) extreme hypoxic states cause the capillaries to move closer to each other due to elongation of myocardial fibers and 2) red cell distribution is not altered during these conditions.     

Stereomorphological arrangement of capillaries in skeletal muscle in normal and stenosed young and adult rats

The stereomorphological arrangement of skeletal muscle capillaries depends on many factors. Genetic biochemical composition of muscle fibers, age, and training can interfere with the growth of the capillary network. This study is focused on the age effect of chronic reduction of blood flow, as in arterial stenosis, in skeletal muscle network of young rats when compared with adult rats. It has been observed that there is a statistically significant decrease of the length of short capillaries which cross the muscle fibers. In adult rats the opposite occurs.