Staphylococcus aureus Formyl-Methionyl Transferase Mutants Demonstrate Reduced Virulence Factor Production and Pathogenicity

Inhibitors of peptide deformylase (PDF) represent a new class of antibacterial agents with a novel mechanism of action. Mutations that inactivate formyl methionyl transferase (FMT), the enzyme that formylates initiator methionyl-tRNA, lead to an alternative initiation of protein synthesis that does not require deformylation and are the predominant cause of resistance to PDF inhibitors in Staphylococcus aureus. Here, we report that loss-of-function mutations in FMT impart pleiotropic effects that include a reduced growth rate, a nonhemolytic phenotype, and a drastic reduction in production of multiple extracellular proteins, including key virulence factors, such as α-hemolysin and Panton-Valentine leukocidin (PVL), that have been associated with S. aureus pathogenicity. Consequently, S. aureus FMT mutants are greatly attenuated in neutropenic and nonneutropenic murine pyelonephritis infection models and show very high survival rates compared with wild-type S. aureus. These newly discovered effects on extracellular virulence factor production demonstrate that FMT-null mutants have a more severe fitness cost than previously anticipated, leading to a substantial loss of pathogenicity and a restricted ability to produce an invasive infection.     

TRPM8 is the principal mediator of menthol-induced analgesia of acute and inflammatory pain

Menthol, the cooling natural product of peppermint, is widely used in medicinal preparations for the relief of acute and inflammatory pain in sports injuries, arthritis, and other painful conditions. Menthol induces the sensation of cooling by activating TRPM8, an ion channel in cold-sensitive peripheral sensory neurons. Recent studies identified additional targets of menthol, including the irritant receptor, TRPA1, voltage-gated ion channels and neurotransmitter receptors. It remains unclear which of these targets contribute to menthol-induced analgesia, or to the irritating side effects associated with menthol therapy. Here, we use genetic and pharmacological approaches in mice to probe the role of TRPM8 in analgesia induced by L-menthol, the predominant analgesic menthol isomer in medicinal preparations. L-menthol effectively diminished pain behavior elicited by chemical stimuli (capsaicin, acrolein, acetic acid), noxious heat, and inflammation (complete Freund’s adjuvant). Genetic deletion of TRPM8 completely abolished analgesia by L-menthol in all these models, although other analgesics (acetaminophen) remained effective. Loss of L-menthol–induced analgesia was recapitulated in mice treated with a selective TRPM8 inhibitor, AMG2850. Selective activation of TRPM8 with WS-12, a menthol derivative that we characterized as a specific TRPM8 agonist in cultured sensory neurons and in vivo, also induced TRPM8-dependent analgesia of acute and inflammatory pain. L-menthol– and WS-12–induced analgesia was blocked by naloxone, suggesting activation of endogenous opioid-dependent analgesic pathways. Our data show that TRPM8 is the principal mediator of menthol-induced analgesia of acute and inflammatory pain. In contrast to menthol, selective TRPM8 agonists may produce analgesia more effectively, with diminished side effects.     

槌果藤软膏治疗银屑病的实验研究

目的:观察槌果藤软膏对银屑病动物模型的疗效及其抗炎、止痒等作用。方法:观察计数小鼠尾部给药后鳞片表皮颗粒层形成情况;计数处于有丝分裂中期的阴道基底细胞有丝分裂数,并换算成有丝分裂指数;观察记录右旋糖苷致小鼠瘙痒次数及瘙痒持续时间;测定二甲苯致小鼠耳廓肿胀程度;测定小鼠腹腔毛细血管炎性渗出。结果:槌果藤软膏对小鼠尾部鳞片表皮颗粒层的形成具有显著的促进作用;可明显抑制小鼠阴道上皮细胞有丝分裂;能明显缓解右旋糖苷引起的小鼠瘙痒;减轻二甲苯致小鼠耳肿胀程度并抑制小鼠腹腔毛细血管通透性增高。结论:槌果藤软膏对小鼠银屑病模型有显著的治疗作用,并具有抗炎、止痒等作用。     

中药荆芥的单萜类化合物

目的：对传统中药荆芥Schizonepeta tenuifolia(Benth.)Briq。中的单萜类化学成分进行研究。方法：溶剂提取、柱层析分离纯化、光谱测定化学结构。结果：从中药荆芥的全草中分离得到2个新的和3个已知的单萜类化合物。结论：根据理化性质和光谱数据，新化合物的结构鉴定为3－羟基－4（8）－烯－对－薄荷烷－3（9）－内酯；1，2－二羟基－8（9）－烯－对－薄荷烷。     

Cloning and expression of the fusion protein of interleukin-2 and ESAT6 in Mycobacterium bovis Bacillus Calmette Guérin strain

Tuberculosis(TB)isthemostcommoncauseofdeathininfectiousdiseases; itisestimatedthatapproximately2millionpeopleperyeardieofTB ThepresentavailableTBvaccineisaliveattenuatedstrain,MycobacteriumbovisBacillusCalmetteGuérin (BCG) However, ithasbeenshownthatBCGhasvariableprotectiveefficacy, rangingfrom 0 to85% indifferentclinicalexperiments 1 Therefore, anewTBvaccineisurgentlyneeded Manytrialshavebeendonetodevelopthesecond generationTBvaccinesinrecentyears; candidatesincludeavirulent, auxotro…     

Mutation and protein expression of p53 in acquired immunodeficiency syndrome-related lymphomas

p53 mutations are found in a variety of neoplasia. B-immunoblastic lymphoma (BIBL) is a rapidly progressive, aggressive lymphoma. As patients with acquired immunodeficiency syndrome (AIDS) live longer, BIBL is becoming an increasing problem. We asked three questions in our study. What is the frequency of p53 mutations in BIBL? Is it more frequent in patients with AIDS? Can immunohistochemical staining of lymph nodes for expression of p53 substitute for mutational analysis of p53 to detect lymphomas with mutated p53? Exons 5, 6, 7, 8 of the p53 gene (hot-spots for mutations) were amplified and examined for mutations by single-strand conformation polymorphism (SSCP) analysis. Altered migration was observed in 7 of 52 BIBL samples. Of these, 4 of 25 were from individuals infected with human immunodeficiency virus (HIV) and 3 of 27 were not infected with HIV. Direct sequencing of amplified material confirmed the presence of mutations in exons 5, 7, 8 of p53. A total of 26 BIBL as well as other lymphoma/leukemia samples, stained strongly by immunohistochemistry with three antibodies directed against human p53. Five of 6 BIBL samples with p53 mutations stained strongly for p53, but 20 lymphoma samples with no detectable p53 mutations also stained strongly for p53. Of note, however, 10 hyperplastic, nonmalignant lymph nodes from individuals either infected or not infected with HIV had negligible staining for p53 protein. In conclusion, p53 mutations occur in about 14% BIBL samples; the frequency of p53 mutations in BIBL in individuals with and without AIDS was similar. Positive p53 immunohistochemistry did not correlate with detectable p53 mutations in the same tissue, but positive immunohistochemical staining for p53 was only found in neoplastic lymph nodes. This latter finding provides a strong warning that p53 immunochemistry with available reagents cannot be used to determine which tumors have mutations of p53.     

Impact of 1, 25-(OH)2D3 on Left Ventricular Hypertrophy in Type 2 Diabetic Rats

Objective To investigate the impact of 1, 25-(OH)2D3 on left ventricular hypertrophy (LVH) in type 2 diabetic rats.
Methods Type 2 diabetic mellitus (DM) model rats were established by intraperitoneally injecting with 30 mg/kg streptozotocin. After 8 weeks, 19 male rats were identified as diabetic with left ventricular hypertrophy (LVH) by ultrasound examination, and randomly assigned into three groups:untreated (DM-LVH, n=7), treated with insulin (DM-LVH+INS, n=6), and treated with 1, 25-(OH)2D3 (DM-LVH+VD, n=6). Healthy male rats were used as the controls group (n=6). The fasting blood glucose and the insulin level were determined weekly. The left ventricular mass index, myocardial collagen content, collagen volume fraction, and 1, 25-(OH)2D3-receptor level were determined by 4 weeks later.
Results In the DM-LVH model group, the insulin level was significantly decreased compared with the non-diabetic control group (P<0.05), whereas the blood glucose, left ventricular mass index, myocardial collagen content, collagen volume fraction, and 1, 25-(OH)2D3-receptor expression were significantly increased (all P<0.05). In the DM-LVH+INS and DM-LVH+VD groups, the insulin levels were significantly increased compared with the DM-LVH model group (P<0.05), whereas the other parameters were significantly decreased (all P<0.05).
Conclusion 1, 25-(OH)2D3 could reverse LVH in diabetic rats and that the mechanism may involve stimulating insulin secretion and reducing blood glucose via direct up-regulation of 1, 25-(OH)2D3-receptor expression.