Renin inhibition reduces hypercholesterolemia-induced atherosclerosis in mice

The role of the renin angiotensin system (RAS) in atherosclerosis is complex because of the involvement of multiple peptides and receptors. Renin is the rate-limiting enzyme in the production of all angiotensin peptides. To determine the effects of renin inhibition on atherosclerosis, we administered the novel renin inhibitor aliskiren over a broad dose range to fat-fed LDL receptor-deficient (Ldlr(-/-)) mice. Renin inhibition resulted in striking reductions of atherosclerotic lesion size in both the aortic arch and the root. Subsequent studies demonstrated that cultured macrophages expressed all components of the RAS. To determine the role of macrophage-derived angiotensin in the development of atherosclerosis, we transplanted renin-deficient bone marrow to irradiated Ldlr(-/-) mice and observed a profound decrease in the size of atherosclerotic lesions. In similar experiments, transplantation of bone marrow deficient for angiotensin II type 1a receptors failed to influence lesion development. We conclude that renin-dependent angiotensin production in macrophages does not act in an autocrine/paracrine manner. Furthermore, in vitro studies demonstrated that coculture with renin-expressing macrophages augmented monocyte adhesion to endothelial cells. Therefore, although previous work suggests that angiotensin peptides have conflicting effects on atherogenesis, we found that renin inhibition profoundly decreased lesion development in mice.     

Transitioning patients from cangrelor to clopidogrel: pharmacodynamic evidence of a competitive effect

BACKGROUND: Cangrelor is a direct, parenteral, and reversible inhibitor of the platelet P2Y12 receptor currently undergoing Phase III testing. As many individuals treated acutely with cangrelor will often be treated long-term with a thienopyridine, it is important to determine the effects of concurrent cangrelor and clopidogrel administration. METHODS AND RESULTS: Ten healthy volunteers received a 600 mg oral loading dose of clopidogrel and then underwent serial platelet function monitoring for 6 h. Two weeks later these same individuals received a 600 mg clopidogrel loading dose simultaneously with a cangrelor IV bolus (30 microg/kg) and a 2-hour infusion (4 microg/kg/min). A separate group of ten volunteers received a 600 mg clopidogrel loading dose after administration of a cangrelor bolus and a 1-hour infusion. The effects on ADP-induced platelet activation and aggregation were evaluated by flow cytometry, whole-blood electrical impedance, and light-transmittance aggregometry. Cangrelor and clopidogrel alone achieved the expected levels of platelet inhibition. However, the sustained platelet inhibition anticipated for clopidogrel treatment did not occur when cangrelor was initiated simultaneously. No such effect was found when clopidogrel was started upon completion of the cangrelor infusion. CONCLUSION: To achieve sustained platelet P2Y12 inhibition in patients treated with cangrelor, clopidogrel administration should be started when the cangrelor infusion is terminated.     

Mutation spectrum and genotype-phenotype analyses in Cowden disease and Bannayan-Zonana syndrome, two hamartoma syndromes with germline PTEN mutation

The tumour suppressor gene PTEN , which maps to 10q23.3 and encodes a 403 amino acid dual specificity phosphatase (protein tyrosine phosphatase; PTPase), was shown recently to play a broad role in human malignancy. Somatic PTEN deletions and mutations were observed in sporadic breast, brain, prostate and kidney cancer cell lines and in several primary tumours such as endometrial carcinomas, malignant melanoma and thyroid tumours. In addition, PTEN was identified as the susceptibility gene for two hamartoma syndromes: Cowden disease (CD; MIM 158350) and Bannayan-Zonana (BZS) or Ruvalcaba-Riley-Smith syndrome (MIM 153480). Constitutive DNA from 37 CD families and seven BZS families was screened for germline PTEN mutations. PTEN mutations were identified in 30 of 37 (81%) CD families, including missense and nonsense point mutations, deletions, insertions, a deletion/insertion and splice site mutations. These mutations were scattered over the entire length of PTEN , with the exception of the first, fourth and last exons. A 'hot spot' for PTEN mutation in CD was identified in exon 5 that contains the PTPase core motif, with 13 of 30 (43%) CD mutations identified in this exon. Seven of 30 (23%) were within the core motif, the majority (five of seven) of which were missense mutations, possibly pointing to the functional significance of this region. Germline PTEN mutations were identified in four of seven (57%) BZS families studied. Interestingly, none of these mutations was observed in the PTPase core motif. It is also worthy of note that a single nonsense point mutation, R233X, was observed in the germline DNA from two unrelated CD families and one BZS family. Genotype-phenotype studies were not performed on this small group of BZS families. However, genotype-phenotype analysis inthe group of CD families revealed two possible associations worthy of follow-up in independent analyses. The first was an association noted in the group of CD families with breast disease. A correlation was observed between the presence/absence of a PTEN mutation and the type of breast involvement (unaffected versus benign versus malignant). Specifically and more directly, an association was also observed between the presence of a PTEN mutation and malignant breast disease. Secondly, there appeared to be an interdependent association between mutations upstream and within the PTPase core motif, the core motif containing the majority of missense mutations, and the involvement of all major organ systems (central nervous system, thyroid, breast, skin and gastrointestinal tract). However, these observations would need to be confirmed by studying a larger number of CD families.      

尿中睾酮与表睾酮的三甲基硅烷化及其比值的GC—MS测定

对睾酮及表睾酮的三甲基硅烷化进行了详细考察,找到了较好的抗氧剂巯基乙醇,确定了较好的衍生化条件,衍生化产物单一。并采用GC—MS法测定了尿中睾酮与表睾酮的比值。实验条件为:以氦为载气,SE—54熔融石英柔性毛细管柱、程序升温进行样品分离,多离子检测(MID),监测m/z432的离子。该法专属、灵敏、快速。睾酮与表睾酮比值在1:1～10:1(睾酮为20ng/μl)与相应峰面积比呈线性关系(r=0.998),最低检测限为1ng,最低检测尿药浓度为8ng/ml。     

Heterogeneity of B cell involvement in acute nonlymphocytic leukemia

In order to study the pattern of B cell involvement in acute nonlymphocytic leukemia (ANLL), multiple B lymphoid cell lines were established by Epstein-Barr virus transformation of peripheral blood mononuclear cells from two patients with the disease who were heterozygous for the X chromosome-linked glucose-6-phosphate dehydrogenase (G6PD). In one patient, the progenitor cells involved by the leukemia exhibited multipotent differentiative expression, whereas in the other patient the cells showed differentiative expression restricted to the granulocytic pathway. In the patient whose abnormal clone showed multipotent expression, the ratio of B-A G6PD in B lymphoid cell lines was skewed in the direction of type B (the enzyme characteristic of the leukemia clone) and significantly different from the 1:1 ratio expected. It is, therefore, likely that the neoplastic event occurred in a stem cell common to the lymphoid series as well as to the myeloid series. In contrast, evidence for B cell involvement was not detected in the patient whose ANLL progenitor cells exhibited restricted differentiative expression. These findings underscore the heterogeneity of ANLL. Clinically and morphologically similar malignancies in these two patients originated in progenitors with different patterns of stem cell differentiative expression. This difference may reflect differences in cause and pathogenesis.     

Modulation of implantation-associated integrin expression but not uteroglobin by steroid hormones in an endometrial cell line

In order to test the hypothesis that integrin and uteroglobin (UG) expression in cultured endometrial cells are affected by hormone treatment, Ishikawa-CH endometrial cancer cells were cultured and exposed to oestradiol or oestradiol and progesterone regimens and assayed using immunohistochemistry. We evaluated the intensity of immunohistochemical staining for the integrin monomers alpha(v) and beta1, the dimers alpha(v)beta3 and alpha(v)beta6, and for the secretory protein uteroglobin under various experimental conditions. Cells grown in control media stained positively for the integrin monomers alpha(v) and beta1, the dimer alpha(v)beta3, and for UG. Oestradiol and sequential oestradiol/progesterone reversibly suppressed staining for the dimer alpha(v)beta3. Hormone treatment had no effect on the staining of the beta1 and alpha(v) monomers or UG. The alpha(v)beta6 dimer antibody did not stain under any experimental treatment conditions. These data indicate that expression of the integrin complex alpha(v)beta3 is reversibly suppressed by oestradiol in Ishikawa cells and that these cells may be a good model for studying hormone-driven molecular changes in endometrium.      

Reaction or infection: topical chloramphenicol treatment

Chloramphenicol is a topical treatment that is used widely, especially in wounds around the eyes. In our practice there have been a number of cases of delayed hypersensitivity to chloramphenicol that has been mismanaged initially as an infective cellulitis. We hope to share some of our experience of this uncommon reaction to highlight the delayed reaction that can occur with topical application of this drug.