Characterization of insulin resistance in type I diabetes

Summary Insulin sensitivity was assessed using the euglycaemic clamp technique in eight type I diabetic patients (after overnight blood glucose normalization with an artificial pancreas) and in six healthy subjects. Basal insulin concentrations were higher in diabetic patients (25±4 µU/ml) than in control subjects (17±1 µU/ml;P<0.05). Insulin infusion of 0.5, 1.0, 2.0 and 5.0 mU/kg per min during subsequent 2-h periods resulted in similar mean steady-state insulin concentrations in both groups. The mean dextrose requirements during the last 40 min of each period were nevertheless decreased in diabetic patients (1.6±0.5, 3.5±0.8, 6.5±0.7, 10.2±0.7 mg/kg per min) as compared with control subjects (4.7±0.3, 8.2±0.9, 10.2±0.9, 12.4±0.9 mg/kg per min). At low insulin concentrations dextrose requirements were diminished in all diabetic subjects. At the highest insulin levels, individual dose-response curves from only four patients were within the normal range. Under basal conditions, the monocyte receptor number was significantly reduced in diabetic patients (17,500±2,800 sites/cell) as compared with control subjects (26,700±2,500 sites/cell;P<0.05), whereas there were no differences regarding empty site affinities. Receptor data did not differ in patients with normal and decreased maximal dextrose requirements.Insulin resistance is apparently a common feature of type I diabetes at serum insulin concentrations of approximately 100 µU/ml. Normalization of the insulin effect by higher insulin concentrations is not possible in all patients. Insulin antibodies at concentrations observed in this study (<0.16 mU/ml) do not contribute significantly to insulin resistance; receptor and postreceptor defects are possibly more important.Abbreviations GCIIS Glucose-controlled insulin infusion system - SSGIR Steady-state glucose infusion rate I.N. and P.A. were fellows of the Deutscher Akademischer Austauschdienst 1981/82 and 1983/84     

Complementary DNA sequence of the HLA‐B*3924 allele1

We have isolated the complete coding region of HLA‐B*39 from a Spanish Caucasoid, using a new PCR primer for its 5′ untranslated region. The cDNA matched partial genomic sequences of B*3924, an allele whose distribution appears to be restricted to Mediterranean and Arabian Caucasoids. A single amino acid change exclusive to B*3924 (threonine‐98) distinguishes it from B*3903.     

Relationship between ischaemic time and ischaemia/reperfusion injury in isolated Langendorff‐perfused mouse hearts

Myocardial functional recovery and creatine kinase (CK) release following various periods of ischaemia were investigated in isolated mouse hearts. The hearts were perfused in the Langendorff mode with pyruvate‐containing Krebs–Hensleit (KH) buffer under a constant perfusion pressure of 80 mmHg, and were subjected to either continuous perfusion or to 5, 15, 20, 25, 30, 45 or 60 min of global ischaemia followed by 45 min of reperfusion. In hearts subjected to ischaemic periods of 5, 15 or 20 min, there was a transient reduction in the left ventricular (LV) dP/dt max during the early phase of reperfusion, while the recovery at the end of reperfusion reached a level similar to that in hearts subjected to continuous perfusion. In hearts subjected to longer ischaemic periods, i.e. 25, 30, 45 or 60 min, the decrease in the cardiac performance was more pronounced and persistent, with significantly lower recovery in LV dP/dt max and higher LV end diastolic pressure (LVEDP) at the end of reperfusion than in the non‐ischaemic hearts. There were no significant differences in the recoveries in coronary flow or in heart rate (HR) between groups. Similarly to the functional recovery, the release of CK showed a clear ischaemic length‐related increase. In conclusion, the Langendorff‐perfused isolated mouse heart could be a valuable model for studies of myocardial ischaemia/reperfusion injury. Future studies using gene‐targeted mice would add valuable knowledge to the understanding of myocardial ischaemia/reperfusion injury.     

糖皮质激素代谢酶11β-羟基类固醇脱氢酶Ⅰ型在新生大鼠脑内的分布与表达

目的　观察新生大鼠脑发育成熟过程中糖皮质激素代谢酶 11β 羟基类固醇脱氢酶Ⅰ型 (11β HSD1)的变化。　方法　免疫组织化学和Western印迹杂交的方法。　结果　免疫组织化学染色表明 ,11β HSD1分布于新生大鼠大脑皮层的各个层次 ,但以Ⅱ层 (外颗粒层 )含量为最高、Ⅲ (锥体细胞层 )、Ⅳ (内颗粒层 )层 11β HSD1的含量次之。海马的各个区域和齿状回也均有 11β HSD1的分布。Western印迹杂交分析表明 ,新生鼠顶叶皮层、海马和下丘脑 11β HSD1的表达在出生后 2周内表达一直比较高 ,第 15d时其表达开始下降。　结论　提示新生鼠大脑 11β HSD1的表达可能与糖皮质激素促进脑组织的发育和成熟有关。     

Trabecular Shear Stresses Predict <Emphasis Type="Italic">In Vivo</Emphasis> Linear Microcrack Density but not Diffuse Damage in Human Vertebral Cancellous Bone

Linear microcracks and diffuse damage (staining over a broad region) are two types of microscopic damage known to occur in vivo in human vertebral trabecular bone. These damage types might be associated with vertebral failure. Using microcomputed tomography and finite element analysis for specimens of cancellous bone, we estimated the stresses in the trabeculae of human vertebral tissue for inferosuperior loading. Microdamage was quantified histologically. The density of in vivo linear microcracks was, but the diffuse damage area was not, related to the estimates of von Mises stress distribution in the tissue. In vivo linear microcrack density increased with increasing coefficient of variation of the trabecular von Mises stress and with increasing average trabecular von Mises stress generated per superoinferior apparent axial stress. Nonlinear increase in linear crack density, similar to the increase of the coefficient of variation of trabecular shear stresses, with decreasing bone stiffness and bone volume fraction suggests that damage may accumulate rather rapidly in diseases associated with low bone density due to the dramatic increase of shear stresses in the tissue. © 2003 Biomedical Engineering Society. PAC2003: 8719Rr, 8719Xx, 8759Ls, 8759Fm, 8710+e     

Na+ channel expression and neuronal function in the Na+/H+ exchanger 1 null mutant mouse

Mice lacking Na(+)/H(+) exchanger 1 (NHE1) suffer from recurrent seizures and die early postnatally. Although the mechanisms for seizures are not well established, our previous electrophysiological work has shown that neuronal excitability and Na(+) current density are increased in hippocampal CA1 neurons of these mutant mice. However, it is unknown whether this increased density is related to altered expression or functional regulation of Na(+) channels. In this work, we asked three questions: is the increased excitability limited to CA1 neurons, is the increased Na(+) current density related to an increased Na(+) channel expression, and, if so, which Na(+) channel subtype(s) is upregulated? Using neurophysiological, autoradiographic, and immunoblotting techniques, we showed that both CA1 and cortical neurons have an increase in membrane excitability and Na(+) current density; Na(+) channel density is selectively upregulated in the hippocampus and cortex (P < 0.05); and Na(+) channel subtype I is significantly increased in the hippocampus and Na(+) channel subtype II is increased in the cortex. Our results demonstrate that mice lacking NHE1 upregulate their Na(+) channel expression in the hippocampal and cortical regions selectively; this leads to an increase in Na(+) current density and membrane excitability. We speculate that neuronal overexcitability due to Na(+) channel upregulation in the hippocampus and cortex forms the basis of epileptic seizures in NHE1 mutant mice.     

Coagulopathy of massive transfusion: pathophysiology and monitoring

Coagulopathy associated with massive transfusion (MT) remains an important clinical problem. The author attempted to identify the causes of coagulopathy in massively transfused, adult and previously haemostatically competent patients and to differentiate between the elective surgical and the emergency settings. A MEDLINE search was conducted for articles published on ‘massive transfusion’, ‘transfusion’, ‘trauma’, ‘surgery’, ‘coagulopathy’ and ‘haemostatic defects’. A narrative format was adopted. Coagulopathy associated with MT is an intricate, multifactorial and multicellular event. In patients undergoing elective surgery, a decrease in fibrinogen concentration is observed initially while thrombocytopenia is a late occurrence. Critically low levels of coagulation factors were seldom reported when whole blood was in common use. With the use of packed red blood cells (PRBC), dilution or consumption of coagulation factors has become a significant issue requiring specific treatment with, primarily, fresh frozen plasma (FFP). In the emergency setting (e.g., trauma, ruptured abdominal aortic aneurysm), tissue trauma, shock, tissue anoxia and hypothermia contribute to the development of disseminated intravascular coagulation and microvascular bleeding. It has been shown that the proactive administration of platelets and FFP improves coagulation, decreases haemorrhage and improves survival in these massively bleeding patients. We can only speculate that in this specific context, the benefits of early and aggressive platelet and coagulation factor replacement are related to the ongoing consumption coagulopathy at the time of surgery.     

Growth hormone deficiency,aortic dilation,and neurocognitive issues in Feingold syndrome 2

We report three patients with Feingold 2 syndrome with the novel features of growth hormone deficiency associated with adenohypophyseal compression, aortic dilation, phalangeal joint contractures, memory, and sleep problems in addition to the typical features of microcephaly, brachymesophalangy, toe syndactyly, short stature, and cardiac anomalies. Microdeletions of chromosome 13q that include the MIR17HG gene were found in all three. One of the patients was treated successfully with growth hormone. In addition to expanding the phenotype of Feingold 2 syndrome, we suggest management of patients with Feingold 2 syndrome include echocardiography at the time of diagnosis in all patients and consideration of evaluation for growth hormone deficiency in patients with short stature.     

戊型肝炎病毒Ⅰ、Ⅱ与Ⅲ、Ⅳ基因型B细胞抗原表位的异同

目的：制备戊型肝炎病毒(HEV)缅甸株和墨西哥株ORF2重组蛋白(p166Bur和p166Mex)的单克隆抗体(McAbs)，用于分析HEV不同基因型B细胞抗原表位的特点。方法：将免疫BALB/C小鼠脾细胞与SP2/0骨髓瘤细胞融合，获得分泌抗-p166Bur和抗-p166Mex McAbs的杂交瘤细胞株，然后采用ELISA和免疫印迹法测定McAbs与不同基因型HEV ORF2编码蛋白p166的免疫反应性。结果：获得4株杂交瘤细胞株，即分泌抗-p166Bur McAbs的2G2、2B1以及分泌抗-p166Mex McAbs的D8G10和E5E12，其中2B1分泌的McAb仅能与第Ⅰ、Ⅱ基因型编码的重组蛋白结合，而其余3株分泌的McAbs既能与Ⅰ、Ⅱ基因型HEV的p166重组蛋白发生反应，也能与Ⅲ、Ⅳ基因型的p166蛋白反应。结论：HEV第Ⅰ、Ⅱ基因型与Ⅲ、Ⅳ基因型ORF2编码蛋白既有共同又有不同的B细胞抗原表位。