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11.
3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (EC 1.1.1.34) is the rate limiting step in the mevalonate pathway that produces isoprenoids and cholesterol. Inhibitors of HMG-CoA reductase are teratogenic in vivo and induce neural tube defects in rat embryo culture, effects which appear unrelated to cholesterol deficiency. This study is the first to localize HMG-CoA reductase mRNA by in situ hybridization (ISH). Expression of reductase mRNA was examined in post-implantation rat embryos, and for control purposes in rat liver and UT-1 cells, using a digoxigenin-11 (dig-11) labelled cRNA probe. Eighteen-day fetal liver showed heavy but patchy hybridization, and adult rat liver showed strong hybridization only on some periportal hepatocytes, which was absent in livers of fasted animals. UT-1 cells stimulated to overexpress HMG-CoA reductase mRNA were strongly positive with the same probe. Control hybridizations with sense strand RNA probe, or with cRNA probe on pre-RNased tissue were negative. Strong hybridization signal for HMG-CoA reductase mRNA was observed in all tissues of the post-implantation rat embryo, from egg cylinder to 30 somite stages (7 to 12 days). Heavy signal was noted in primitive ectoderm and neural tube. The wide embryonic and extraembryonic distribution and abundance of HMG-CoA reductase mRNA may reflect developmental requirements for products of the mevalonate pathway, e.g., isoprenoids for post-translational farnesylation of p21ras.  相似文献   
12.
拓宏伟 《现代电子技术》2010,33(9):132-135,140
针对工业测控的现状和需求,提出一种新型测控方案,并对其关键技术进行了研究。系统采用双DSP工作模式,并在此基础上提出了并行FFT算法,实现了双余度数据采集及处理,提高了数据处理效率;采用RS 485无线通信方式实现数据和控制信号收发;上位机端基于LabVIEW开发平台实现了信号收发,并提供ODBC数据库接口,将虚拟仪器技术和面向Internet的Web技术有机结合起来,很好地满足了监测系统互联和资源共享的需求。  相似文献   
13.
通过结构优化组合,采用铝化成箔(Al/Al2O3)极片为正极,活性炭极片(AC/Al)为负极,研制了电压为16V的多正极混合超级电容器。通过增加正极数量,进一步提高能量密度。多项电化学性能测试显示:多正极混合超级电容器具有快速充放电能力,与1000μF铝电解电容器相比,能量密度提高了约9倍,阻抗曲线接近理想电容器,内阻约为0.05?。  相似文献   
14.
Resistance to nalidixic acid. A misconception due to underdosage   总被引:1,自引:0,他引:1  
The clinical impression of inordinate selection of resistant mutants to nalidixic acid cannot be substantiated on close scrutiny when sensitive infections are treated at a full dosage of 4 gm/day. When 27 consecutive patients were treated with 4 gm of nalidixic acid per day, resistance developed in the bacteriuric population in only 7%. Moreover, resistance in the fecal reservoir was surprisingly minimal and much less than that reported for sulfonamides, tetracyclines, and ampicillin. The observation is important because multiply-resistant Enterobacteriaceae maintain their sensitivity to nalidixic acid since extrachromosomal R-factor resistance to nalidixic acid has never been demonstrated and cannot be transferred from one organism to another. In vitro data on 100 sensitive strains of Enterobacteriaceae show that the developmental of resistance to nalidixic acid is inversely proportional to the concentration of nalidixic acid regardless of whether the inoculum size is 10(5) or 10(8) bacteria per milliliter. Underdosage (less than 4 gm/day) with nalidixic acid is the probable cause of excessive resistance.  相似文献   
15.
16.
The elemental composition of different types of keratohyalin granules from the epidermis of newborn and adult rats was studied by means of an EMMA-4 analytical electron microscope, equipped with an energy-dispersive X-ray spectrometer. An absolute quantitation of the sulphur concentration in keratohyalin granules was performed. The results demonstrate that epidermal keratohyalin granules are chemically heterogeneous. A type of keratohyalin granule present in the nuclei and cytoplasm of epidermal cells from both newborn and adult rats - termed single granules - is rich in sulphur, having a content of 2-5-3-6%. Other types of keratohyalin granules, which differ in newborn and adult rats, contain a sulphur-poor component; they often have a sulphur-rich component as well. The sulphur-poor keratohyalin contains 0-6-0-9% sulphur. It is suggested that the sulphur-rich keratohyalin granules are the source of the peripheral envelope protein of cornified cells.  相似文献   
17.
Thyroid scans were performed at 4 and 24 hr after administration of Na123I solution in 124 examinations. The 4-hr and 24-hr scans were found to be of equal diagnostic value. Thus, in individuals with structural thyroid abnormalities, one can effectively reduce the time required for scan evaluation from the standard 24 hr to 4 hr.  相似文献   
18.
On the basis of own observations of courses the author adopts a definite attitude to the early symptomatology of the rheumatoid arthritis. During the first weeks of the rheumatoid arthritis the following symptoms are found: articular syndromes, more frequently in form of obstinate polyarthralgias, mono-oligoarthritis, accompanied by morning rigidity and accelerated BSR as well as impairment of the general condition. In the majority of the patients only the tentative diagnosis rheumatoid arthritis may be made. After a one to three months' course of the disease the diagnosis becomes more probable. It is above all based on constancy and symmetry, characteristic localisation of the articular process, morning rigidity, radiologically paraarticular loosening of the structure and morphological symptoms of an acute and subacute synovialitis. 6 to 12 months after the beginning of the disease a clinical picture forms which allows to make the diagnosis of a certain or classical rheumatoid arthritis in accordance with the criteria of the ARA. The occurrence of a high activity of multiple affection of the joints (permanent symmetrical polyarthritis including the small joints of the hands and feet), distinctive morning rigidity, high fever and much accelerated BSR, beginning with the first weeks of the disease, speaks for the possibility of the development of an arthrovisceral form of the course of rheumatoid arthritis.  相似文献   
19.
Renovascular hypertension is the most prevalent form of surgically remediable hypertension. With appropriate selection of operative candidates, a high rate of cure or improvement may be anticipated. Favorable results justify revascularization in hypertensive patients with focal arteriosclerotic renal artery disease. The absence of advanced arteriosclerosis provides the most valid basis for predicting long-term survival following revascularization. Patients with clinically demonstrable diffuse arteriosclerotic disease are preferably treated medically; we consider them candidates for surgery only if drug therapy cannot control blood pressure. Renal revascularization does not appear to alter the inexorable progression of concomitant generalized arteriosclerosis. Revascularization rather than nephrectomy is the primary surgical therapy for renal artery stenosis in properly selected patients.  相似文献   
20.
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