Mechanism of regulation of 8-hydroxyguanine endonuclease by oxidative stress: roles of FNR, ArcA, and Fur

We found previously that 8-hydroxyguanine (oh8Gua) endonuclease in E. coli is induced in response to oxidative stress in a fashion similar to the oxidative response of the Mn-superoxide dismutase (MnSOD). In this study, attempts were made to identify the genes involved in the co-regulation of E. coli endonuclease and MnSOD (sodA). oh8Gua nuclease is induced by molecular oxygen and a superoxide radical generator (paraquat) but not by H2O2, suggesting that the regulation of this endonuclease is dependent on SoxRS but independent of OxyR. This enzyme was induced by paraquat in all of the soxRS mutant strains used (soxR-, soxS- and soxRc), whereas glucose-6-phosphate dehydrogenase (a member of the soxRS regulon) showed the expected responses; therefore, this possibility was excluded. The presence of metal chelators in the growth medium caused the induction of this enzyme, and this induction was suppressed by the addition of Fe++. Consistent with this finding, this enzyme was expressed under anaerobiosis in all of the mutant strains of fnr in particular, as well as fur, arcA, and combinations thereof. These findings suggest that the oxidative regulation of oh8Gua endonuclease is under control of fnr, fur, and arcA, where fnr plays a predominant role. The multiple involvement of regulatory genes as well as co-regulation with antioxidant enzyme will enhance the efficiency of cellular growth and survival in the aerobic environment.     

Detection of Salmonella in dry foods using refrigerated pre-enrichment and enrichment broth cultures: summary of collaborative study

A collaborative study was conducted to compare the productivity of refrigerated pre-enrichment and enrichment broth cultures with the U.S. Food and Drug Administration culture methods for detection of Salmonella. The refrigerated pre-enrichment and selective enrichment broth culture methods for detection of Salmonella in dry foods have been adopted first action by AOAC INTERNATIONAL.     

Allogeneic bone marrow transplantation for high-risk acute lymphoblastic leukemia in first remission: long-term results for 42 patients conditioned with an intensified regimen (TBI, high-dose Ara-C and melphalan)

Attempts to improve the efficacy of pretransplant conditioning regimens have been published, the potential of a better antileukemic effect being impaired by more frequent and severe toxicities. The efficacy of an intensified regimen, TAM (TBI, high-dose cytosine arabinoside and melphalan), is evaluated by analyzing long-term follow-up of a homogenous group of 42 high-risk ALL patients allografted in first CR. Age at time of BMT was 25.9 +/- 10.4 years (3-41). Twenty-two patients had more than three adverse prognostic factors. Ten patients had a Ph chromosome. Probability of overall survival was 45 +/- 9%, and for all surviving patients median follow-up time was 66 months. Event-free survival was 40 +/- 8% at 7 years after transplantation and the expected relapse rate reached 31%. Twenty-two deaths occurred, six after a relapse but 16 appeared to be directly due to the BMT procedure. None of the pretransplant characteristics significantly affected outcome after BMT. TAM appeared to be an efficient antileukemic therapy for conditioning high-risk ALL patients before allogeneic transplantation, but was still very toxic. The use of TAM in adult ALL patients in first CR is not recommended and the real role of intensified conditioning regimens remains to be demonstrated.     

The effect of focal cerebral cooling on perinatal hypoxic-ischemic brain damage

We describe a method of focal cooling of the head and its effects on hypoxic-ischemic cerebral damage in neonatal rat. Focal cooling of the head was obtained by positioning a catheter under the scalp ipsilateral to the ligated common carotid artery and by running cold water through the catheter during 2 h of systemic hypoxia. Hypoxia was produced in neonatal rats by breathing 8% oxygen for 2 h in a 37 degrees C chamber. Animals underwent focal cooling with ipsilateral scalp temperatures ranging from 22 degrees C to 35 degrees C. Temperature recordings from the ipsilateral scalp, cerebral hemisphere (dorsal hippocampus) and core (rectal) were obtained. The results suggest that the method is effective in cooling of brain and also to a lesser extent in lowering of the core temperature. At a mean scalp temperature of 28 degrees C, mean hippocampal temperature in hypoxic rat was 29.5 degrees C and mean core temperature in hypoxic rat was 32.8 degrees C. At a lower scalp temperature of 22 degrees C, mean hippocampal temperature in hypoxic rat was 24.7 degrees C and mean core temperature was 31.3 degrees C. Neuropathologic examination 3-4 days following hypoxia-ischemia showed that focal cooling with a scalp temperature of lower than 28 degrees C completely protected from brain damage, and that there was a trend towards greater damage with higher scalp temperatures.     

Effect of castration and steroid treatments on the activity of some hydrolytic enzymes in dog prostate

Adult mongrel dogs were castrated and treated by intramuscular injections of 5 alpha-androstane-3 alpha,17 beta-diol (androstanediol) alone or in combination with estradiol in order to find convenient enzymatic markers of hormone action in prostate. The activities of 15 hydrolytic enzymes were determined. Arginine esterase, acid sulfatase, and acid phosphatase were found to be the most sensitive markers of testicular hormones since they were decreased 18-, 5- and 5-fold respectively after 1 month of castration. The enzyme activities returned to precastration levels after 2 weeks of injection of androstanediol to castrated animals. The effect of androstanediol on the majority of the remaining enzymes was small. In general, the activities obtained after androstanediol treatment in combination with estradiol were similar to those obtained with androstanediol alone. Finally, beta-glucuronidase and neutral sulfatase were increased after castration, a finding that suggests that these enzymes are constituents of stromal cells. These studies will provide a basis for future studies of hormone action in the dog prostate.     

综观PC产业三大变化方向

80年代开始,PC就一直影响人们的生活,从最初的8086/8088架构,到现在GHz的Pentium时代,PC创造了半导体、PC外围、零部件与光电产业的庞大商机.时光进入2004年,随着数字家庭或者说是多媒体中心风潮的到来,使得大家的焦点不再只是单纯放在微处理器的时脉速度,取而代之的是无线局域网的能力、与视觉享受有关的绘图处理器与监视器、高品质的音效及内存容量与传输速度.     

Intraoperative radiotherapy in 1997

Codon usage bias of 1,117 Drosophila melanogaster genes, as well as fewer D. pseudoobscura and D. virilis genes, was examined from the perspective of relative abundance of isoaccepting tRNAs and their changes during development. We found that each amino acid contributes about equally and highly significantly to overall codon usage bias, with the exception of Asp which had very low contribution to overall bias. Asp was also the only amino acid that did not show a clear preference for one of its synonymous codons. Synonymous codon usage in Drosophila was consistent with "optimal" codons deduced from the isoaccepting tRNA availability. Interestingly, amino acids whose major isoaccepting tRNAs change during development did not show as strong bias as those with developmentally unchanged tRNA pools. Asp is the only amino acid for which the major isoaccepting tRNAs change between larval and adult stages. We conclude that synonymous codon usage in Drosophila is well explained by tRNA availability and is probably influenced by developmental changes in relative abundance.     

A closed culture system for the ex vivo transduction and expansion of human T lymphocytes

The purpose of this qualitative study was to explore traditional beliefs and practices related to pregnancy and childbirth among Native American women and examine the relationship of these beliefs and practices to current use of prenatal care. Focus groups of elders and young women were held and the data analyzed with the Ethnograph software. The central theme was the breakdown in transmission of cultural wisdom among Native American women. The major causes described by women were federal assimilation policies and deaths of elders. Major factors influencing young women's nonutilization of prenatal care were this breakdown, the "Western model" of prenatal care, substance abuse, and domestic violence. Recommendations for improving the use of prenatal care are grounded in the reality that Native American women live in two different worlds. Prenatal care should be reconceptualized as traditional cultural wisdom, with the majority of care provided by natural helpers in the Native American community, including tribal elders, grandmothers, and aunts in collaboration with licensed providers.