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排序方式: 共有228条查询结果,搜索用时 15 毫秒
1.
Circannual variation in lymphocyte subsets, revisited 总被引:2,自引:0,他引:2
BACKGROUND: Circadian and circannual variations in lymphocyte subsets, especially CD8+ T-lymphocytes, have been reported. This study focuses on CD4+ T-lymphocyte seasonal variation over a 6-year 8-month period. STUDY DESIGN AND METHODS: Lymphocyte subsets were quantitated monthly for four healthy individuals from 1986 through 1992 as part of a flow cytometry quality-control program. RESULTS: In general, there were no significant seasonal changes in the total number of white cells or in total lymphocyte counts. The absolute numbers of CD4+ T-lymphocytes were lowest in summer when the CD8+ T-lymphocytes were highest. Mean CD4+ T-lymphocyte counts were 846, 967, 618, and 695 per microL for Subjects 1 through 4, respectively, in winter and 432, 670, 355, and 766 per microL, respectively, in summer. Two healthy subjects had CD4+ T-lymphocyte counts lower than 300 per microL on one or more occasions during the study period. In three of the four subjects, the percentage of B-lymphocytes in winter was almost double that in summer. In one of the four subjects, no circannual rhythm was observed in these lymphocyte subpopulations. CONCLUSION: The seasonal variation in CD4+ T- lymphocyte counts demonstrated in three healthy individuals over almost 7 years is again of interest in light of renewed consideration of using surrogate tests, such as CD4+ T-lymphocyte counts, to screen for AIDS- like diseases that may be in the blood supply. 相似文献
2.
The family history in family practice: a questionnaire study 总被引:9,自引:7,他引:2
OBJECTIVES: Our aims were to investigate family medical history taking in
general practice, and to evaluate the value attached to the family medical
history as an aid to decision making in general practice. METHOD: A postal
questionnaire survey was conducted among all 291 GPs working within the
Calderdale and Kirklees Health Authority area. Each questionnaire was
followed by a reminder. The main outcome measures were answers to questions
on routine and opportunistic family history taking and a question about
transmitting knowledge about genetic risk to other members of the family.
Questions were also posed about the value attached to the family medical
history as an aid to decision making. RESULTS: A total of 193 GPs returned
the questionnaire (response rate 66.3%). On registration, 94.3% of GPs
indicated that enquiries were made about a family history of coronary heart
disease. Breast and colorectal cancer were specifically asked about by
48.4% and 30.7% of GPs, respectively. One-fifth of respondents indicated
that they asked a general question about family medical history. A little
over one-quarter of respondents indicated that they made opportunistic
enquiries about the family history or suggested that the patient should
inform other members of the family about possible risks. In the scenarios
highlighted in this study, the majority of respondents felt that the family
medical history had value as an aid to decision making. This was
particularly the case for checking a patient's cholesterol (92.1%) and for
initiating referrals in younger patients with possible cancer-related
symptoms (three-quarters of respondents). CONCLUSION: GPs value the family
medical history as an aid to decision making. Unfortunately, apart from
enquiries about coronary heart disease, routine or opportunistic family
history taking is not occurring in practice. Mechanisms need to be sought
to extract information from the family medical history so that it can be
more effectively used by GPs.
相似文献
3.
Christian Stock Birgit Gassner Christof R. Hauck Hannelore Arnold Sabine Mally Johannes A. Eble Peter Dieterich Albrecht Schwab 《The Journal of physiology》2005,567(1):225-238
Their glycolytic metabolism imposes an increased acid load upon tumour cells. The surplus protons are extruded by the Na+ /H+ exchanger (NHE) which causes an extracellular acidification. It is not yet known by what mechanism extracellular pH (pHe ) and NHE activity affect tumour cell migration and thus metastasis. We studied the impact of pHe and NHE activity on the motility of human melanoma (MV3) cells. Cells were seeded on/in collagen I matrices. Migration was monitored employing time lapse video microscopy and then quantified as the movement of the cell centre. Intracellular pH (pHi ) was measured fluorometrically. Cell–matrix interactions were tested in cell adhesion assays and by the displacement of microbeads inside a collagen matrix. Migration depended on the integrin α2β1. Cells reached their maximum motility at pHe ∼7.0. They hardly migrated at pHe 6.6 or 7.5, when NHE was inhibited, or when NHE activity was stimulated by loading cells with propionic acid. These procedures also caused characteristic changes in cell morphology and pHi . The changes in pHi , however, did not account for the changes in morphology and migratory behaviour. Migration and morphology more likely correlate with the strength of cell–matrix interactions. Adhesion was the strongest at pHe 6.6. It weakened at basic pHe , upon NHE inhibition, or upon blockage of the integrin α2β1. We propose that pHe and NHE activity affect migration of human melanoma cells by modulating cell–matrix interactions. Migration is hindered when the interaction is too strong (acidic pHe ) or too weak (alkaline pHe or NHE inhibition). 相似文献
4.
Controlled proteolysis of the multifunctional protein that initiates pyrimidine biosynthesis in mammalian cells: evidence for discrete structural domains. 总被引:1,自引:4,他引:1 下载免费PDF全文
M I Mally D R Grayson D R Evans 《Proceedings of the National Academy of Sciences of the United States of America》1981,78(11):6647-6651
The multifunctional protein that initiates de novo pyrimidine biosynthesis in mammalian cells carries carbamoylphosphate synthetase, aspartate transcarbamylase (aspartate carbamoyltransferase), and dihydro-orotase activities on a single 215,000-dalton polypeptide chain. Kinetic studies of the controlled proteolysis of the molecule by elastase showed that the protein was not attacked at random by the protease but rather was successively cleaved into at least six well-defined proteolytic fragments. The initial cleavage converted the intact molecule into a 190,000-dalton species which appeared to retain all of the catalytic and regulatory functions of the native protein. This species was subsequently cleaved into two fragments, 150,000 and 40,000 daltons. The 40,000-dalton species, which carried the aspartate transcarbamylase activity, was resistant to further proteolysis; the 150,000-dalton polypeptide, which carried carbamoyl-phosphate synthetase and dihydro-orotase activities, underwent further digestion to 140,000 daltons. Continued proteolysis produced two species, 79,000 and 45,000 daltons; like the 40,000-dalton species, these were stable against further elastase digestion. The aspartate transcarbamylase and dihydro-orotase activities and the regulatory functions were preserved throughout the course of digestion; the carbamoylphosphate synthetase activity was more labile. By using sucrose gradient centrifugation and ion exchange chromatography, the 40,000- and 45,000-dalton species have been isolated. The 40,000-dalton fragment was found to have only aspartate transcarbamylase activity; the 45,000-dalton fragment has only dihydro-orotase activity. These experiments showed that this multifunctional protein is organized as discrete structural domains in which regions of the polypeptide chain are autonomously folded into separate functional units. 相似文献
5.
Staedt Henning Mally Eva Scheller Herbert Wentaschek Stefan Kämmerer Peer Wolfgang Kasaj Adrian Devigus Alessandro Lehmann Karl Martin 《Clinical oral investigations》2021,25(1):145-150
Clinical Oral Investigations - This study evaluated the reproducibility of electronic color determination system evaluations of the marginal gingiva, which could be important for adhesive cervical... 相似文献
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Alexander L Lundberg Ramon Lorenzo-Redondo Egon A Ozer Claudia A Hawkins Judd F Hultquist Sarah B Welch PV Vara Prasad James F Oehmke Chad J Achenbach Robert L Murphy Janine I White Robert J Havey Lori Ann Post 《JMIR Public Health and Surveillance》2022,8(1)
BackgroundVariants of the SARS-CoV-2 virus carry differential risks to public health. The Omicron (B.1.1.529) variant, first identified in Botswana on November 11, 2021, has spread globally faster than any previous variant of concern. Understanding the transmissibility of Omicron is vital in the development of public health policy.ObjectiveThe aim of this study is to compare SARS-CoV-2 outbreaks driven by Omicron to those driven by prior variants of concern in terms of both the speed and magnitude of an outbreak.MethodsWe analyzed trends in outbreaks by variant of concern with validated surveillance metrics in several southern African countries. The region offers an ideal setting for a natural experiment given that most outbreaks thus far have been driven primarily by a single variant at a time. With a daily longitudinal data set of new infections, total vaccinations, and cumulative infections in countries in sub-Saharan Africa, we estimated how the emergence of Omicron has altered the trajectory of SARS-CoV-2 outbreaks. We used the Arellano-Bond method to estimate regression coefficients from a dynamic panel model, in which new infections are a function of infections yesterday and last week. We controlled for vaccinations and prior infections in the population. To test whether Omicron has changed the average trajectory of a SARS-CoV-2 outbreak, we included an interaction between an indicator variable for the emergence of Omicron and lagged infections.ResultsThe observed Omicron outbreaks in this study reach the outbreak threshold within 5-10 days after first detection, whereas other variants of concern have taken at least 14 days and up to as many as 35 days. The Omicron outbreaks also reach peak rates of new cases that are roughly 1.5-2 times those of prior variants of concern. Dynamic panel regression estimates confirm Omicron has created a statistically significant shift in viral spread.ConclusionsThe transmissibility of Omicron is markedly higher than prior variants of concern. At the population level, the Omicron outbreaks occurred more quickly and with larger magnitude, despite substantial increases in vaccinations and prior infections, which should have otherwise reduced susceptibility to new infections. Unless public health policies are substantially altered, Omicron outbreaks in other countries are likely to occur with little warning. 相似文献