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排序方式: 共有591条查询结果,搜索用时 15 毫秒
1.
W D Lovan R A Weaver R J Lentz J K Goodrum B F Withers 《Aviation, space, and environmental medicine》1986,57(4):370-375
The Naval Special Board of Flight Surgeons was established in 1956 for the evaluation of Navy, Marine Corps, and Coast Guard problem aeromedical cases. This paper examines a sample 248 of these cases for the period of 1974-83 with respect to the characteristics of those referred, their referral diagnostic category, and the recommendation of the Special Board regarding return to a flying status. Those cases with a referral diagnostic category of ENT and Ophthalmology were less likely to be returned to flight status. Older, more senior pilots, and pilots with more total flight time were less likely to be returned to unrestricted flying than were their younger, more junior, and less experienced counterparts. Otherwise, no significant difference in outcome based on age, rank, marital status, branch of service, specialty, or flight hours was detected. Overall, 61% of those evaluated by the SBFS were returned to flight status. 相似文献
2.
Alteration in myelin-associated proteins following spinal cord irradiation in guinea pigs. 总被引:3,自引:0,他引:3
C S Chiang K A Mason H R Withers W H McBride 《International journal of radiation oncology, biology, physics》1992,24(5):929-937
The aim of this study was to investigate the pathological and cellular basis for radiation-induced myelopathy in guinea pigs by monitoring biochemical alterations in levels of myelin basic protein and 2',3'-cyclic nucleotide phosphohydrolase. Guinea pigs were irradiated to the lumbar region with various doses of neutrons or cobalt gamma irradiation. The ED50s for paralysis were 17.2 Gy and 67.5 Gy for neutron and cobalt irradiation, respectively, and was histologically associated with demyelination. In spinal cords taken from animals at the onset of paralysis myelin basic protein levels were decreased in direct relationship to the radiation dose. The lowest doses to cause paralysis led to a 25% decrease in MBP levels. In a separate experiment, alterations in MBP were measured in the spinal cords over the time period leading up to paralysis. Surprisingly, decreases in MBP were found immediately after the end of the 4 week irradiation period. These early changes in MBP were not markedly dose dependent and occurred with nonparalyzing doses. Dose-dependent decreases were found only just before the onset of paralysis. CNPase activity measured in the same specimens showed changes that were essentially similar to those for MBP. In the CSF, MBP levels were essentially constant until onset of paralysis. This study showed that demyelination, as assessed by the levels of the myelin-associated proteins MBP and CNPase, can occur soon after spinal cord irradiation but that profound dose-dependent changes are seen only immediately preceding the onset of paralysis. Although increases in MBP in the CSF were associated with the onset of radiation-induced myelopathy, its assay is unlikely to predict this complication of irradiation. 相似文献
3.
A new commercial kit, MEASLESTAT M (Whittaker Bioproducts, Inc.), was compared with the sucrose density gradient centrifugation-hemagglutination inhibition method for the detection of measles virus-specific immunoglobulin M. Overall agreement between the two procedures was 97.1% for 104 single and paired serum samples tested. The sensitivity and specificity of MEASLESTAT M were 98.4 and 95.2%, respectively. 相似文献
4.
R. T. Withers N. O. Whittingham K. I. Norton J. La Forgia M. W. Ellis A. Crockett 《European journal of applied physiology》1987,56(2):169-180
Summary Ninety-one percent (n=182) of the female members of South Australian representative squads in 14 sports volunteered to act as subjects. Twenty-seven percent of them had represented Australia. The underwater weighing method together with the measurement of residual volume (RV) by helium dilution were used to determine body density (BD); the percent body fat (% BF) was then computed according to Siri.A stepwise multiple regression analysis yielded a correlation coefficient (R) of 0.863 between the criterion (BD) and the best weighted sum of predictors (anthropometric variables): BD (g·cm–3)=1.14075–0.04959 (log10 triceps, subscapular, supraspinale and calf skinfolds in mm)+0.00044 (age in decimal years)–0.000612 (waist girth in cm)+0.000284 (height in cm)–0.000505 (gluteal girth in cm)+0.000331 (breast girth in cm).Only those predictors which resulted in a statistically significant increase inR (p0.05) were included. The standard error of estimate of 0.00597 g · cm–3 was equivalent to 2.7% BF at the mean. This equation was shown to be largely population specific. There was a range of 7.6–35.8% of BF and the overall mean of 18.5% was significantly lower (p<0.001) than that of 23.4% obtained on a moderately active reference sample of similar age (n=135). If group sizes of only one or two are regarded as too small for meaningful comparison, then the lowest mean of 13.5% was achieved by the long-distance runners (n=14). The highest averages were registered by the heavyweight rowers (24.2%;n=7) and soccer players (22.0%;n=11). The overall average for games players (n=107) was 19.4%.This study was supported by a grant from the National Health and Medical Research Council of Australia 相似文献
5.
Zimian Wang Moonseong Heo Robert C. Lee Donald P. Kotler Robert T. Withers Steven B. Heymsfield 《American journal of human biology》2001,13(5):612-619
Muscularity, or the proportion of adipose tissue‐free body mass (ATFM) as skeletal muscle (SM), provides valuable body composition information, especially for age‐related SM loss (i.e., sarcopenia). Limited data from elderly cadavers suggest a relatively constant SM/ATFM ratio, 0.540 ± 0.046 for men (mean ± SD, n = 6) and 0.489 ± 0.049 for women (n = 7). The aim of the present study was to examine the magnitude and constancy of the SM/ATFM ratio in healthy adults. Whole‐body SM and ATFM were measured using multi‐scan magnetic resonance imaging. The SM/ATFM ratio was 0.528 ± 0.036 for men (n = 139) and 0.473 ± 0.037 for women (n = 165). Multiple regression analysis indicated that the SM/ATFM ratio was significantly influenced by sex, age, body weight, and race. The four factors explained 50% of the observed between individual variation in the SM/ATFM ratio. After adjusting for age, body weight, and race, men had a larger SM/ATFM ratio than women. Both older men and women had a lower SM/ATFM ratio than younger subjects, although the relative reduction was greater in men. After adjustment for sex, age, and body weight, there were no significant differences in the SM/ATFM ratios between Asian, Caucasian, and Hispanic subjects. In contrast, African‐American subjects had a significantly greater SM/ATFM ratio than subjects in the other three groups. In addition, the SM/ATFM ratio was significantly lower in AIDS patients than corresponding values in healthy subjects. Am. J. Hum. Biol. 13:612–619, 2001. © 2001 Wiley‐Liss, Inc. 相似文献
6.
7.
R M Robins-Browne S Tzipori G Gonis J Hayes M Withers J K Prpic 《Journal of medical microbiology》1985,19(3):297-308
Yersinia enterocolitica is an important cause of enteritis and mesenteric adenitis in many countries. However the pathogenesis of the disease caused by this organism has not been fully elucidated. Most isolates from clinical material possess two independent properties associated with virulence whose relative contribution to the development of disease is not known. These are the ability to penetrate the intestinal wall, which is thought to be controlled by a plasmid gene, and the production of heat-stable enterotoxin, which is controlled by a chromosomal gene. In this study, we infected neonatal gnotobiotic piglets with strains of Y. enterocolitica expressing these two properties in various combinations. The suitability of the piglet model was shown in experiments in which piglets fed virulent Y. enterocolitica serogroup O3 developed a clinical illness related to the size of the inoculum, which was accompanied by intestinal lesions similar to those reported in naturally and experimentally infected people and animals. The results confirmed the key role of a 47 X 10(6)-mol. wt plasmid in the pathogenicity of Y. enterocolitica, but suggested that penetration of the intestinal wall may be governed by chromosomal rather than plasmid-borne genes. No role for enterotoxin in the pathogenesis of yersiniosis was shown, although there was evidence that enterotoxin may promote intra-intestinal proliferation of Y. enterocolitica, thus favouring increased shedding of bacteria and encouraging their spread between hosts. 相似文献
8.
In mice, activation induced deaminase, AID, is expressed only in germinal center B cells. It is required for the initiation of somatic hypermutation and class switch recombination. In chickens and most mammals immunoglobulin gene rearrangement generates limited diversity and the primary immunoglobulin repertoire depends on subsequent somatic hypermutation or gene conversion. Immunoglobulin gene conversion in chickens starts in the embryonic bursa, before antigen exposure. The demonstrated requirement for AID for gene conversion in the bursal lymphoma cell line, DT40, implies developmental regulation of AID expression. To test this prediction, we examined the timing and location of AID mRNA expression. An abrupt increase in AID mRNA coincided with the onset of extensive Ig gene conversion in the bursa. Expression was also detected at earlier stages, implying either that expression of AID is not the only controlling factor for gene conversion, or that gene conversion can precede the formation of bursal follicles. 相似文献
9.
Cloning of rabies virus matrix protein mRNA and determination of its amino acid sequence 总被引:2,自引:1,他引:2
A cDNA clone of mRNA for rabies virus matrix (M) protein has been identified. The clone hybridizes to an mRNA species from rabies virus-infected cells, whose size correlates to the size of the M protein in rabies virions, and selects an mRNA that translates into a polypeptide corresponding in size to M protein. The nucleotide sequence of the cloned cDNA was determined and from this a complete amino acid sequence for M protein was deduced. The deduced sequence of 202 amino acids bears no detectable sequence homology with vesicular stomatitis virus M protein although these proteins may share functional homology. 相似文献
10.
An assay for the survival of renal tubule cells was developed using mice. It is analogous to other in-situ clonogenic cell survival assays. One kidney was irradiated using a 137Cs irradiator and removed 60-68 weeks later for histological examination. In unirradiated animals there were about 370 tubules in contact with the capsule in a coronal cross section at the middle of the kidney. After irradiation, extensive tubular damage was the dominant lesion. The number of epithelialized tubules in contact with the capsule showed a dose-dependent logarithmic decline. The dose-survival relationship for the clonogenic cells responsible for the regeneration of tubule epithelium was described by a D0 value of 1.5 Gy over the dose range 11-16 Gy. This radiosensitivity resembles that of stem cells in acutely responding tissues. The lack of histological evidence of damage to the arterial vasculature at the time the tubules are initially denuded of epithelium, and the similarity of renal tubule cell radiosensitivity to that of other mammalian cells, support the hypothesis that "late" radiation injury results primarily from depletion of parenchymal cells, not indirectly from injury to blood vessels, as has been the prevailing belief. 相似文献