Polymorphism of the thiopurine S-methyltransferase gene in African- Americans

The molecular basis for the genetic polymorphism of thiopurine S - methyltransferase (TPMT) has been estab-lished for Caucasians, but it remains to be elucidated in African populations. In the current study, we determined TPMT genotypes in a population of 248 African-Americans and compared it with allele frequencies in 282 Caucasian Americans. TPMT genotype was determined in all individuals with TPMT activity indicative of a heterozygous genotype (</=10.1 U/ml pRBC, n = 23African- Americans, n = 21 Caucasians) and a control group with TPMT activity indicative of a homozygous wild-type genotype (>10.2 U/ml pRBC, n = 23 African-Americans, n = 21 Caucasians). No mutant alleles were found in the high activity control groups. The overall mutant allele frequencies were similar in African-Americans and Caucasians (4.6 and 3.7% of alleles, respectively). However, while TPMT*3C was the most prevalent mutant allele in African-Americans (52.2% of mutant alleles), it represented only 4.8% of mutant alleles in Caucasians ( P < 0.001). In contrast, TPMT*3A and TPMT*2 were less common in African-Americans (17.4 and 8.7% of mutant alleles), whereas TPMT*3A was the most prevalent mutant allele in Caucasians (85.7% of mutant alleles). A novel allele ( TPMT*8 ), containing a single nucleotide transition (G644A), leading to an amino acid change at codon 215 (Arg-->His), was found in one African-American with intermediate activity. These data indicate that the same TPMT mutant alleles are found in American black and white populations, but that the predominant mutant alleles differ in these two ethnic groups.      

Interleukin-1 stimulates human uterine prostaglandin production through induction of cyclooxygenase-2 expression

PROBLEM: Uterine infection occurs in as much as 20% of preterm labor and results in increased decidual cytokines. The objective of this study was to examine the effect of interleukin-1 (IL-1) and the cyclooxygenase-2 (COX-2) inhibitor, NS-398, on myometrial prostaglandin (PG) production and COX-2 expression. METHOD OF STUDY: Human uterine myocytes were stimulated with IL-1 (0-50 ng/mL) over 24 hr. PGE2, PGF2alpha, and 6-keto F1alpha were measured by enzyme-linked immunosorbent assay. Both COX-1 and COX-2 proteins and mRNA were measured by western and northern blot, respectively. RESULTS: IL-1 increased PG production beginning at 6 hr, COX-2 protein increased beginning at 4 hr and continued to increase at 24 hr. COX-2 mRNA increased at 2 hr and peaked at 4 hr. NS-398 blocked PG production but had no effect on COX-2 protein or mRNA. CONCLUSIONS: IL-1 increases PG production by myometrium by increased COX-2 expression. NS-398 completely blocks IL-1-induced PG production. With intrauterine infection, IL-1 may induce labor through the autocrine production of uterotonic PGs.     

骨骼肌缺血再灌注损伤及发病机制初探

目的：探讨骨骼肌缺血再灌注损伤过程的微循环变化。组织学改变以及多肽含量变化和意义。方法：42只雄性大鼠随机分为留伴行神经组和去伴行神经组,建立标准骨骼肌缺血再灌注模型,采用激光多谱勒及显微放大分析系统,组织学方法以及凝胶电泳方法等观察缺血再灌注损伤变化。结果：缺血再灌注损伤后的骨骼肌微血管管径在20分钟时恢复率基本达到高峰约60％,此后为平台期：90分钟最高峰,为75％,主干血管流速率亦在20分钟基本达到上限,病理检查显示：缺血的骨骼肌纤维呈空泡状,核形态增大,染色加深,红细胞严重聚集,凝胶蛋白电泳提示：缺血骨骼肌中分子量20KD左右的多肽显著增加。结论：骨骼肌缺血再灌注损伤发生后,骨骼肌的微循环发生不同程度的破坏,及因之导致骨骼结构损伤和异常的20KD多肽含量明显增加,以及红细胞凝聚,白细胞的改变,这些共同构成了缺血再灌注损伤机制。     

Monoclonal antibody-based enzyme immunoassay for detection of ricin

A sensitive and specific enzyme-linked immunoadsorbent assay (ELISA) was developed to detect ricin in biological fluids. The assay is based on the sandwich format using monoclonal antibodies (MAbs) of two distinct specificities. An affinity-purified anti-ricin B chain MAb (1G7) is utilized to adsorb ricin from solution and the second anti-ricin A chain MAb (5E11) conjugated with peroxidase is then used to form a sandwich, and peroxidase allows color development and measurement of optical density at 450 nm. Standard curves were linear over the range of 2.5-100 ng/mL ricin. The limit of detection was below 5 ng/mL in assay buffer as well as in a 1:10 dilution of urine or 1:50 dilution of human serum spiked with ricin.     

Diosgenin induces hypoxia-inducible factor-1 activation and angiogenesis through estrogen receptor-related phosphatidylinositol 3-kinase/Akt and p38 mitogen-activated protein kinase pathways in osteoblasts

Diosgenin, extracted from the root of wild yam (Dioscorea villosa), has been reported to demonstrate an opportunity for medical application. Vascular endothelial growth factor-A (VEGF-A) plays an important role in bone-related angiogenesis, a critical process occurring during bone formation and fracture healing. In this study, we examine whether diosgenin is able to induce VEGF-A expression and to promote angiogenesis in osteoblasts. For murine MC3T3-E1 preosteoblast-like cells, VEGF-A mRNA and protein expression seemed to be significantly elevated in response to diosgenin in a concentration-dependent fashion. Conditioned media prepared from cells treated with diosgenin induced strong angiogenic activity in either in vitro or ex vivo angiogenesis assay. Furthermore, diosgenin treatment increased the stability and activity of HIF-1alpha protein. Inhibition of HIF-1alpha activity by transfection with DN-HIF-1alpha significantly diminished diosgenin-mediated VEGF-A up-regulation. The use of pharmacological inhibitors or genetic inhibition revealed that both the phosphatidylinositol 3-kinase (PI3K)/Akt and p38 signaling pathways were potentially required for diosgenin-induced HIF-1 activation and subsequent VEGF-A up-regulation. It is noteworthy that an estrogen receptor binding assay revealed that diosgenin has the strong ability to replace [(3)H]estradiol bound to estrogen receptor (IC(50), 10 nM). In addition, the specific estrogen receptor antagonists ICI 182,780 (faslodex) and tamoxifen were noted to be able to strongly inhibit diosgenin-induced, src kinase-dependent Akt and p38 MAPK activation. Taken together, such results provide evidence that diosgenin up-regulates VEGF-A and promotes angiogenesis in preosteoblast-like cells by a hypoxia-inducible factor-1alpha-dependent mechanism involving the activation of src kinase, p38 MAPK, and Akt signaling pathways via estrogen receptor.     

ALCOHOL AND ENDOCRINE SYSTEMS INTERACTION—PART II Biochemical Mechanisms That Contribute to Alcohol-Induced Hypogonadism in the Male

The above review has presented most if not all of the available evidence supporting a role for alcohol and acetaldehyde as putative environmental Leydig cell toxins for man and animals. Despite a considerable data base and much progress, particularly in the last decade, much yet remains to be learned concerning this phenomenon. It is hoped that this review, and this symposium, will contribute to future progress in this area by providing a basis for new and provocative observations and hypotheses to be tested by a new generation of clinical investigators.     

The effect of clonidine on gastrointestinal side effects associated with ultra-rapid opioid detoxification

IMPLICATIONS: Clonidine, an alpha(2)-adrenergic agonist, is used to minimize withdrawal symptoms related to ultra-rapid opioid detoxification procedures. These preliminary data suggest that clonidine possesses dose-related antidiarrheal activity.