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101.
Shirmohammadi D. Rajagopalan C. Alward E.R. Thomas C.L. 《Power Systems, IEEE Transactions on》1991,6(3):1006-1016
Major technical issues are discussed related to the cost of transmission transactions provided by a vertically integrated electric utility company. The authors identify the components of the cost of a transmission transaction and present methodologies for evaluating them using simple examples. The major cost components of a transmission transaction are: operating cost; opportunity cost; reinforcement cost; and existing system cost. The evaluation of these components requires the development of new analytical and knowledge-based techniques 相似文献
102.
Mesangial cells of the renal glomerulus are thought to have contractile properties, resembling those of smooth muscle cells. Since actin synthesis in mesangial cells is increased in selected animal models of glomerulonephritis, we evaluated the expression of alpha-smooth muscle actin (ASMA), the principal actin isoform found in smooth muscle cells, in biopsy specimens from patients with primary glomerular disorders and in control tissues. Normal glomeruli and glomeruli in acute tubulointerstitial disorders showed few or no ASMA-positive cells in the glomeruli. In contrast, ASMA expression in mesangial cells was increased in minimal change disease, focal segmental glomerulosclerosis, mesangial proliferative glomerulonephritis, membranous glomerulonephritis, and immunoglobulin A nephropathy. In membranoproliferative glomerulonephritis and cryoglobulinemic glomerulonephritis both mesangial and capillary loop ASMA-positive cells were observed with a segmental distribution. In addition, ASMA-positive interstitial cells were seen in many biopsy specimens and often were increased in number in biopsy specimens showing early interstitial fibrosis and tubular atrophy. We conclude that ASMA synthesis in mesangial cells is upregulated in a variety of glomerular disorders, frequently associated with increased cell proliferation and mesangial matrix production. This phenotypic change may be an indicator of mesangial cell activation after injury and may have important pathophysiologic consequences. 相似文献
103.
This prospective study was conducted over a period of 18 months (February 1989 to July 1990) in the State of Kuwait. It covered a population of 1,024,211 and eight multidisciplinary hospitals with an in-patient admission of 118,079 per year. Two hundred and twenty-six adult patients with acute renal failure (ARF) were seen and followed up by nephrologists. This made the calculated annual incidence of ARF 14.7 per 100,000 population, nearly five times that reported by the EDTA registry (Biesenbach et al. 1991). Drugs, sepsis and volume depletion were the most frequent causes, with sepsis resulting in 36% cause specific mortality compared to zero mortality with the other two. The overall mortality rate was only 14% which clearly indicated a markedly improved prognosis in cases of ARF. The prognosis in ARF depended on two major factors, viz. the type of aetiological insult and the presence of predisposing associated medical illnesses. Multiple insults, though common, do not affect the mortality rate. Secondary sepsis or gastrointestinal bleeding as a cause of death in ARF was rarely seen in our study. Those who required dialytic support for renal failure had a 45% patient mortality rate in general. Over 40% of our patients were 60 years or older compared with only 3.5% in the local population. This indicated old age as a major risk factor in the development of ARF. The overall mortality in the elderly did not differ from that in the young, but sepsis in the elderly carried a mortality rate of 60% compared to only 14.8% in the younger age group. 相似文献
104.
KV Fernandes PA Sabelli DH Barratt M Richardson J Xavier-Filho PR Shewry 《Canadian Metallurgical Quarterly》1993,23(1):215-219
A cDNA encoding a cysteine proteinase inhibitor was isolated from a cDNA library prepared from developing seeds of an insect-resistant line of cowpea. The sequence of the encoded protein was homologous with those of other plant cysteine endoproteinase inhibitors, and with Type 2 cystatins from animals. Southern blot analyses indicated that small gene families were present in both resistant and susceptible lines of cowpea, while northern blot analyses showed similar levels of expression. It is concluded that the levels of expression of the inhibitor do not account for the differences in insect resistance of the two lines. 相似文献
105.
Drug resistance in cancer poses a major problem to the success of chemotherapy. Increased resistance to the DNA-damaging chemotherapeutic drug cisplatin may be associated with a variety of factors including decreased drug accumulation, increased intracellular levels of thiols, and increased DNA repair. We have found that mutants of the Chinese hamster ovary (CHO) and the mouse adrenocortical carcinoma Y1 cells harboring a defective regulatory subunit (RI) of the cAMP-dependent protein kinase (PKA) exhibited increased resistance to cisplatin. These mutants are cross-resistant to other DNA-damaging chemotherapeutic agents, including bleomycin and melphalan. In addition, wild-type CHO cells transfected with and overexpressing the yeast phosphodiesterase gene or a dominant mutant Rl alpha subunit gene also displayed similar increased resistance to cisplatin. However, mutants with altered catalytic (C) subunits showed a sensitivity to cisplatin similar to the wild-type cells. Further analysis by gel shift assay using cisplatin-damaged DNA as probes and nuclear extracts derived from the Rl subunit mutants showed increased binding of nuclear factor(s) to the damaged DNA. In addition, a host cell reactivation assay of DNA repair, using a cisplatin-damaged reporter plasmid, detected enhanced capacity for repair of DNA lesions in the PKA mutants. These results suggest that DNA repair may be increased in the PKA mutants. We speculate that functional inactivation of PKA may result in increased DNA repair and the acquisition of resistance to DNA-damaging anticancer drugs in cancer. 相似文献
106.
The type II antifreeze proteins (AFPs) of smelt and Atlantic herring are homologous to the carbohydrate-recognition domains (CRDs) of Ca2+-dependent (C-type) animal lectins and, like these lectins, acquire a stable and active structure upon binding Ca2+ ions. In the C-type lectin CRD, the carbohydrate-binding site is located at a Ca2+-binding site. Site-directed mutagenesis was used to test the hypothesis that the ice-binding site of the type II AFP corresponds to the carbohydrate-binding site of the lectins. To disrupt this site in the herring AFP without perturbing the Ca2+-dependent protein fold, a double mutant was constructed that changed the Ca2+- and carbohydrate-binding motif from the galactose-type of wild-type AFP containing the sequence Gln-Pro-Asp to a mannose-type that has the sequence Glu-Pro-Asn and is also known to bind Ca2+. The mutant AFP exhibited proper Ca2+ binding, folding, and stability as demonstrated by ruthenium red staining, proteolysis protection assays, and CD spectroscopy. However, it showed no antifreeze activity (thermal hysteresis) and did not alter ice crystal morphology to form bipyramidal crystals as does the active wild-type AFP. These results demonstrate that the ice-binding site of the herring type II AFP corresponds to the carbohydrate-binding site of the C-type lectin CRDs and further suggest that this ice-binding function evolved from the carbohydrate-binding site of a preexisting C-type lectin. 相似文献
107.
The incidence of both hip fracture and stroke increases with age. With the increasing age of the United States population, it is expected that the orthopaedic nurse will be challenged to care for clients with the dual disabilities of hip fracture and stroke. This article discusses incidence of these disabilities, describes the pathophysiology of stroke, and uses a case study to outline specific nursing interventions for the patient with hip fracture and stroke. 相似文献
108.
An 18 month Thoroughbred gelding was diagnosed on cardiac catheterization as having an interventricular septal defect. Right side cardiac blood pressures were within the normal range and confirmation of the diagnosis came from changes in the blood pO2 and pCO2 between the right atrium and right ventricle. The significance of these values is discussed. 相似文献
109.
Dasgupta PK Martinelango PK Jackson WA Anderson TA Tian K Tock RW Rajagopalan S 《Environmental science & technology》2005,39(6):1569-1575
Perchlorate, an iodide uptake inhibitor, is increasingly being detected in new places and new matrices. Perchlorate contamination has been attributed largelyto the manufacture and use of ammonium perchlorate (the oxidizer in solid fuel rockets) and/or the earlier use of Chilean nitrate as fertilizer (approximately 0.1% perchlorate). However, there are regions such as the southern high plains (Texas Panhandle) where there is no clear historical or current evidence of the extensive presence of rocket fuel or Chilean fertilizer sources. The occurrence of easily measurable concentrations of perchlorate in such places is difficult to understand. In the southern high plains groundwater, perchlorate is better correlated with iodate, known to be of atmospheric origin, compared to any other species. We show that perchlorate is readily formed by a variety of simulated atmospheric processes. For example, it is formed from chloride aerosol by electrical discharge and by exposing aqueous chloride to high concentrations of ozone. We report that perchlorate is present in many rain and snow samples. This strongly suggests that some perchlorate is formed in the atmosphere and a natural perchlorate background of atmospheric origin should exist. 相似文献
110.