A cytoplasmic component of pyridine nucleotide fluorescence in rat diaphragm: evidence from comparisons with flavoprotein fluorescence

Pyridine nucleotide (PN) and flavoprotein (Fp) fluorescence were monitored in the isolated intact rat diaphragm. A substantial increase in PN fluorescence occurred when N₂ replaced O₂ in glucose medium. This response was much reduced in pyruvate medium and/or by pretreatment with iodoacetic acid (IAA). The anaerobic levels of Fp fluorescence were less affected by substrate and IAA. Substitution of glucose by pyruvate did not alter the PN fluorescence of the resting aerobic tissue, but increased Fp fluorescence. After a tetanus with glucose present the PN of the anaerobic muscle, but not the Fp underwent a substantial transient oxidation. This oxidation was absent in pyruvate medium. It is concluded that a cytoplasmic component of the PN fluorescence is present in skeletal muscle. The levels of Fp fluorescence in the resting and contracting aerobic tissue supplied with pyruvate suggest that the resting tissue respiration was ADP limited. On this basis the level of PN fluorescence in the aerobic resting state was less than expected; the source of the PN fluorescence was both mitochondrial and cytoplasmic.     

Mutations in activation-induced cytidine deaminase in patients with hyper IgM syndrome

Recent studies have shown that mutations in a newly described RNA editing enzyme, activation-induced cytidine deaminase (AID), can cause an autosomal recessive form of hyper IgM syndrome. To determine the relative frequency of mutations in AID, we evaluated a group of 27 patients with hyper IgM syndrome who did not have defects in CD40 ligand and 23 patients with common variable immunodeficiency. Three different mutations in AID were identified in 18 patients with hyper IgM syndrome, including 14 French Canadians, 2 Lumbee Indians, and a brother and sister from Okinawa. No mutations were found in the remaining 32 patients. In the group of patients with hyper IgM syndrome, the patients with mutations in AID were older at the age of diagnosis, were more likely to have positive isohemagglutinins, and were less likely to have anemia, neutropenia, or thrombocytopenia. Lymphoid hyperplasia was seen in patients with hyper IgM syndrome and normal AID as well as the patients with hyper IgM syndrome and defects in AID.     

血管紧张素Ⅱ受体1和受体2在小鼠肾脏发育中的表达

目的观察小鼠肾脏发育中血管紧张素Ⅱ受体1(AngiotensinⅡreceptor type1,AT_1)和受体2 (AT_2)的表达特征,探讨小鼠肾脏发育过程中AT_1和AT_2的作用及相互关系。方法应用免疫组织化学技术、免疫印迹法(Western blot)并结合体视学方法检测胚龄12、14、15、16、18d及生后日龄1、3d小鼠肾脏发育中AT_1和AT_2的表达。结果AT_1和AT_2均首先出现在输尿管芽,然后出现在肾小管,生后表达逐渐减弱。早期肾小体内AT_2丰富表达,随着肾小体的成熟表达量逐渐降低。结论在小鼠肾脏发育中,AT_1可能与输尿管芽分支不断延长以及肾小管的增殖密切相关,AT_2可能与输尿管芽和肾小体的相互诱导相关。     

菊藤胶囊对应激大鼠血压、血浆血管紧张素Ⅱ和血液流变学的影响

目的观察中药复方菊藤胶囊对慢性应激性高血压大鼠血压、血浆血管紧张素Ⅱ（AngⅡ）及血液流变学的影响。方法大鼠随机分为6组（每组7只）：应激＋蒸馏水组（model），应激＋菊藤胶囊高剂量组（JT—H），应激＋菊藤胶囊中剂量组（JT—M），应激＋菊藤胶囊低剂量组（JT—L），应激＋卡托普利组（captopril），正常对照组（control）；除正常对照组外，其余5组均采用低频低压交流电间断电击法。电击大鼠足底28d，制作应激性高血压模型，同时各组均加入不同的干预。后应用经尾动脉测量血压和心率，酶联免疫吸附法（ELISA）检测大鼠血浆血管紧张素Ⅱ，血液流变学和细胞流变学的各项指标。观察比较菊藤胶囊不同剂量组、卡托普利组对应激致大鼠血压及相关指标的影响。结果与正常对照组相比，模型组大鼠血压和血浆血管紧张素Ⅱ含量明显升高（P〈0．01）。全血黏度、血浆黏度、纤维蛋白原及红细胞聚集指数均明显升高（P〈0．05），红细胞变形指数无变化。与模型组相比，菊藤胶囊高、中组均能抑制应激大鼠的血压及血浆血管紧张素Ⅱ含量的升高（P〈0．01），菊藤胶囊高剂量能明显改善应激大鼠的血液流变性（P〈0．05），低剂量组应激大鼠的血液流变学无明显改变（P〉0．05）。结论菊藤胶囊能够降低应激性高血压大鼠的血压，其机理可能是通过降低血浆中血管紧张素Ⅱ的含量和改善血液流变和细胞流变性实现的。     

<Emphasis Type="Italic">Helicobacter pylori</Emphasis> and <Emphasis Type="Italic">cagA</Emphasis> and <Emphasis Type="Italic">vacA</Emphasis> gene status in children from Brazil with chronic gastritis

Helicobacter pylori has been shown to be strongly associated with chronic gastritis, gastric and duodenal ulceration, and is a risk factor for gastric carcinoma. Histology, urease, culture, and polymerase chain reaction have been employed as for H. pylori diagnostic methods, pre and post treatment or during follow-up of dyspeptic adult individuals referred for endoscopy. In order to obtain a more-sensitive and specific method for H. pylori detection, we evaluated gastric body and antrum biopsies of 134 consecutive Brazilian consecutive dyspeptic children aged 1-16 years by rapid urease test, histology and polymerase chain reaction using two pairs of oligonucleotides. Our results indicated that polymerase chain reaction with Southern blotting and hybridization with specific chemiluminescent probes increased the number of positive H. pylori patients by 35%. The genotyping of H. pylori strains directly from gastric biopsy using the same nucleic acid methodology revealed that there is no association of chronic gastritis in our infant patients with vacA s1 and the presence of the cagA gene. These data suggest an initial infection of children with normal mucosa and probably others factors than vacA s1 genotype or the presence of the cagA gene are associated with the onset of gastric disease. Altogether, our results reinforce the need for using more sensitive diagnostic methods in order to understand the role of H. pylori in the genesis of gastric disease in children and its progression in adults.     

心肌肥厚大鼠心肌组织中5-羟色胺及血管紧张素-Ⅱ含量的变化

目的：观察大鼠发生心肌肥厚时心肌组织中5-羟色胺（5-HT）及血管紧张素-Ⅱ（Ang-Ⅱ）含量的变化，探讨5-HT、Ang-Ⅱ与心肌肥厚发生的关系。方法：采用腹主动脉缩窄法建立压力超负荷心肌肥厚模型；腹腔注射甲状腺素法建立体液性心肌肥厚模型；荧光分光光度法和放射免疫分析法测定5-HT及Ang-Ⅱ含量。结果：大鼠腹主动脉缩窄后8周，心肌肥厚明显，分别于主动脉缩窄后4-8周内处死动物，发现心肌肥厚程度逐渐加重；心肌组中5-HT及Ang-Ⅱ含量也逐渐增加，并与肥厚程度呈正相关。腹腔注射甲状腺素2周后出现心肌肥厚，4周时症状加剧；于2、3、4周时处死动物，发现肥厚心肌组织中5-HT和Ang-Ⅱ含量均显著增加。结论：提示5-HT与心肌肥厚的形成有关，二者之间的相互关系尚待进一步研究。     

Activation of murine dendritic cells and macrophages induced by Salmonella enterica serovar Typhimurium

Macrophages and dendritic cells (DCs) are antigen-presenting cells (APCs), and the direct involvement of both cell types in the immune response to Salmonella has been identified. In this study we analysed the phenotypic and functional changes that take place in murine macrophages and DCs in response to live and heat-killed Salmonella enterica serovar Typhimurium. Both types of cell secreted proinflammatory cytokines and nitric oxide (NO) in response to live and heat-killed salmonellae. Bacterial stimulation also resulted in up-regulation of costimulatory molecules on macrophages and DCs. The expression of major histocompatibility complex (MHC) class II molecules by macrophages and DCs was differentially regulated by interferon (IFN)-gamma and salmonellae. Live and heat-killed salmonellae as well as lipopolysaccharide (LPS) inhibited the up-regulation of MHC class II expression induced by IFN-gamma on macrophages but not on DCs. Macrophages as well as DCs presented Salmonella-derived antigen to CD4 T cells, although DCs were much more efficient than macrophages at stimulating CD4 T-cell cytokine release. Macrophages are effective in the uptake and killing of bacteria whilst DCs specialize in antigen presentation. This study showed that the viability of salmonellae was not essential for activation of APCs but, unlike live bacteria, prolonged contact with heat-killed bacteria was necessary to obtain maximal expression of the activation markers studied.     

骨骼肌介电行为的理论模型仿真

在 10 0 Hz～ 10 0 MHz范围内 ,应用椭圆壳介电理论模型 ,经过模拟仿真蛙骨骼肌细胞的介电行为 ,确定了蛙骨骼肌细胞的椭圆壳模型各相参数。为将来对骨骼肌疲劳、肌营养不良和肌肉萎缩等病症的模型分析奠定理论基础。     

Force deficits after stretches of activated rat muscle-tendon complex with reduced collagen cross-linking

The forces produced during stretches of passive and activated muscles, and isometric force deficits after stretching of activated muscles were examined in rat plantor flexor muscle-tendon complexes with reduced collagen cross-links (pyridinoline). Female Sprague-Dawley rats (n=6, age 87 days) were injected twice daily for 43 days with β-aminopropionitrile (BAPN, 333 mg/kg/day i.p.), an inhibitor of lysyl oxidase, which is responsible for the production of collagen cross-links. The relative weights of the plantar flexor muscles were similar for BAPN and saline-injected (control, C) rats (n=6). Pyridinoline was lower in the tendon (22.9%), and in the plantaris (17.1%), and soleus (7.4%) muscles (P<0.05), with no changes observed in collagen content (hydroxyproline), as determined by high-pressure liquid chromatography. At an ankle position of 90°, groups had similar forces at 5, 10, 20, 40, 60 and 80 Hz before stretching. Forces at 40° with stretches of the passive muscles (five times from 90° to 40°) were lower for all stretches in BAPN-injected rats (P<0.05). Isometric force deficits resulting from stretches of activated muscles (80 Hz, 20 times from 90° to 40°, rest intervals 3 min) followed similar courses for BAPN-injected and C rats, and were 51.1 (2.4)% (C) and 54.7 (4.6)% (BAPN) before the last stretch. After 1 h of rest, isometric force deficits were 26% and 29% larger at 10 Hz and 5 Hz, respectively, in BAPN-treated rats (P<0.05). The reduction in BAPN-injected collagen cross-linking of the skeletal muscle-tendon complex reduced the forces produced during stretches without muscle stimulation (i.e. passive stretch), and stretching of activated muscles produced larger isometric force deficits only at low stimulation frequencies. Electronic Publication     

The rational design of TAP inhibitors using peptide substrate modifications and peptidomimetics

The major histocompatibility complex (MHC)-encoded transporter associated with antigen processing (TAP) translocates peptides from the cytosol into the lumen of the endoplasmic reticulum. This step precedes the binding of peptides to MHC class I molecules and is essential for cell surface expression of the MHC class I/peptide complex. TAP has a broad sequence specificity and a preference for peptides of around 9 amino acids. To synthesize inhibitors for TAP, we studied various alterations of the peptide substrate. The results indicate that TAP is stereospecific and that peptide bonds engineered into isosteric structures can improve translocation of the peptide. Furthermore, TAP is able to translocate peptides with large side chains that correspond to a peptide of ～ 21 amino acids in extended conformation. Peptides with longer side chains compete for the peptide binding site of TAP but fail to be translocated. Therefore, they represent the first rationally designed inhibitors of TAP.