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排序方式: 共有1693条查询结果,搜索用时 15 毫秒
91.
Williams HA Robinson S Julyan P Zweit J Hastings D 《European journal of nuclear medicine and molecular imaging》2005,32(12):1473-1480
Purpose PET radiotracers which incorporate longer-lived radionuclides enable biological processes to be studied over many hours, at centres remote from a cyclotron. This paper examines the radioisotope characteristics, imaging performance, radiation dosimetry and production modes of the four copper radioisotopes, 60Cu, 61Cu, 62Cu and 64Cu, to assess their merits for different PET imaging applications. Methods Spatial resolution, sensitivity, scatter fraction and noise-equivalent count rate (NEC) are predicted for 60Cu, 61Cu, 62Cu and 64Cu using a model incorporating radionuclide decay properties and scanner parameters for the GE Advance scanner. Dosimetry for 60Cu, 61Cu and 64Cu is performed using the MIRD model and published biodistribution data for copper(II) pyruvaldehyde bis(N4-methyl)thiosemicarbazone (Cu-PTSM). Results 60Cu and 62Cu are characterised by shorter half-lives and higher sensitivity and NEC, making them more suitable for studying the faster kinetics of small molecules, such as Cu-PTSM. 61Cu and 64Cu have longer half-lives, enabling studies of the slower kinetics of cells and peptides and prolonged imaging to compensate for lower sensitivity, together with better spatial resolution, which partially compensates for loss of image contrast. 61Cu-PTSM and 64Cu-PTSM are associated with radiation doses similar to [18F]-fluorodeoxyglucose, whilst the doses for 60Cu-PTSM and 62Cu-PTSM are lower and more comparable with H215O. Conclusion The physical and radiochemical characteristics of the four copper isotopes make each more suited to some imaging tasks than others. The results presented here assist in selecting the preferred radioisotope for a given imaging application, and illustrate a strategy which can be extended to the majority of novel PET tracers. 相似文献
92.
Low-income families face an enormous burden to achieve economic security since the deterioration of a guaranteed safety net. Health insurance coverage is uneven, affordable childcare falls short of demand, and wage earnings insufficiently support family needs. This analysis focuses on recent trends in family formation, the impact of policy changes on families of color and of immigrant status, and explores the daily challenges and coping strategies low-income families use to survive despite insufficient resources. Four key findings emerge from this body of knowledge: (1) Low-income families experience severe hardships when relying on cash assistance, work, or a combination of both; (2) Low-income families are resilient and resourceful; (3) Low-income families face significant barriers to using public and private services along with increasing earnings from work; and (4) The quality of life for families of color and immigrant families is directly affected by employment and service sector practices. Future research needs to focus on identifying the critical unmet needs of low-income families. 相似文献
93.
BACKGROUND AND PURPOSE: Diabetes mellitus (DM)-related neuropathic arthropathy of the foot is a destructive bone and joint process. The effect of cast immobilization and non-weight bearing on bone loss has not been well studied. The purpose of this case report is to describe the changes in bone mineral density (BMD) of the calcaneus in the feet of a patient with acute neuropathic arthropathy during total contact cast immobilization. CASE DESCRIPTION: The patient was a 34-year-old woman with type 1 DM, renal failure requiring dialysis, and a 7-week duration of neuropathic arthropathy of the midfoot. Intervention included total contact casting and minimal to no weight bearing for 10 weeks, with transition to therapeutic footwear. Ultrasound-derived estimates of BMD were taken of both involved and uninvolved calcanei. OUTCOME: Bone mineral density decreased for the involved foot (from 0.25 g/cm(2) to 0.20 g/cm(2)) and increased for the uninvolved foot (from 0.27 g/cm(2) to 0.31 g/cm(2)) during casting. DISCUSSION: The low initial BMD and further loss during casting suggest the need for transitional bracing and a well-monitored return to full activity to minimize the risk of recurrence and progression of foot deformity. 相似文献
94.
Russell A. Barkley James E. Hastings Robert E. Tousel Susan E. Tousel 《Journal of behavior therapy and experimental psychiatry》1976,7(3):227-230
The influence of a token economy in a residential treatment facility for delinquents was evaluated in three areas of behavior: (a) in-house chore performance, (b) littering in the facility, and (c) school performance as reflected in daily evaluations by teachers. Chore performance and littering were influenced favorably by the token system. School performance, however, appeared to be unaffected by the reversal of the token program. Reasons for this finding are discussed and the need underscored that existing token systems evaluate the effectiveness of their program contingencies on a regular basis. 相似文献
95.
96.
Cetra D. Hastings Inger Brekke A. Attramadal Vidar Hansson 《International journal of andrology》1980,3(1-6):72-81
The present paper describes some physicochemical properties of the soluble 3α-oxidoreductases in the rat testis and prostate, and comparison with rat epididymal 3α-oxidoreductase, published previously (Hastings & Hansson 1979). The testicular enzyme shows properties very similar to that in the epididymis (size, stability, pH optium) except for minor differences in charge (iso-electric point). The prostatic enzyme revealed a slightly higher molecular weight, and was more sensitive to heating than those in the testis and epididymis, whereas the iso-electric point was the same as that in the testis (pI-5.25). The enzymes in all tissues exhibit very similar shapes (f/fo 1.14-1.17).
The similar properties of the testicular and prostate 3α-oxidoreductases to those previously reported for that in the epididymis may indicate that these enzymes represent identical peptide chains. The small differences observed in size, temperature stability and change may be due to their presence in different environments. 相似文献
The similar properties of the testicular and prostate 3α-oxidoreductases to those previously reported for that in the epididymis may indicate that these enzymes represent identical peptide chains. The small differences observed in size, temperature stability and change may be due to their presence in different environments. 相似文献
97.
The morphology and development of junctional complexes between blastomeres of the preimplantation rabbit embryo were investigated using several approaches. Electron microscopic examination of embryos stained en bloc with uranyl acetate, and the study of junction permeability using horseradish peroxidase and lanthanum nitrate provided information on structure, intermembrane spacing and permeability of the junctional complexes. In addition, the freeze fracture technique was used with day 5 and day 6 blastocysts, since the large size of these embryos facilitated use of this method. These experiments showed that although rudimentary junctions were present between blastomeres of the early cleavage stages, effective tight junctions were not present until the blastocyst stage. Electron microscopic examination of thin sections revealed apical foci of membrane approximation or "fusion" between trophoblast cells by day 4. Freeze fracturing revealed a lattice of interconnecting ridges (on the A face) and grooves (on the B face) in the apical region between trophoblast cells of the day 5 blastocyst. This lattice formed a continuous band along the apical margin of each cell, and therefore constituted a zonula occludens. The zonula occludens of the day 5 blastocyst averages 2-3 ridges per lattice, while day 6 blastocysts had lattices that averaged 5-6 ridges. Also seen in the freeze fracture replicas from the day 5 and day 6 blastocysts were local accumulations of intramembranous particles on the A face. These particles were often observed in aggregates similar to those of previously described gap junctions. It could not be determined whether these small regions of particles were true gap junctions or a possible primitive form of gap junction because the complementary pitted surfaces (B face pits) were not demonstrated. 相似文献
98.
Cullen M Steven N Billingham L Gaunt C Hastings M Simmonds P Stuart N Rea D Bower M Fernando I Huddart R Gollins S Stanley A;Simple Investigation in Neutropenic Individuals of the Frequency of Infection after Chemotherapy +/- Antibiotic in a Number of Tumours 《The New England journal of medicine》2005,353(10):988-998
99.
100.
Boeree MJ Sauvageot D Banda HT Harries AD Zijlstra EE 《Tropical medicine & international health : TM & IH》2005,10(8):723-733
OBJECTIVE: To assess the efficacy and safety of two different dosages of cotrimoxazole (CTX) in prophylaxis in HIV-positive new smear-positive pulmonary tuberculosis (TB) patients in Blantyre, Malawi. METHOD: Randomized, double-blind trial using 480 and 960 mg of CTX given to new TB patients, who were followed up until the end of the tuberculosis treatment. The primary outcome was survival. The outcome in the two groups was also compared with an unselected cohort of similar patients registered in Zomba, Malawi in 1995 and new smear-positive patients registered in the National Tuberculosis Programme in 1999. The secondary outcome was the occurrence of (opportunistic) events, especially bacterial pneumonia. RESULTS: There were no statistically significant differences in mortality and bacterial pneumonia between the groups receiving the two different dosages. The case fatality rate at the end of the tuberculosis treatment was 15.4% in the 480 mg group and 14.0% in the 960 mg group. This was lower than the case fatality rate in the Zomba cohort (19.2%, P = 0.10) and lower than the case fatality rate in the national programme (21.0%, P < 0.001). CTX was well tolerated. Compliance was fair. CONCLUSIONS: CTX prophylaxis may have a beneficial effect on mortality and morbidity in HIV-infected smear-positive tuberculosis patients in Malawi. The efficacy of both dosages is not significantly different. The intervention is cheap and easy to implement. These results would support implementation of CTX in this patient group until better strategies are available or evidence is convincingly presented to suggest that its benefit is marginal. 相似文献