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Anderson RA; Wallace AM; Kicman AT; Wu FC 《Human reproduction (Oxford, England)》1997,12(8):1657-1662
Administration of supraphysiological doses of testosterone to normal men
causes inhibition of spermatogenesis, but while most become azoospermic,
30-55% maintain a low rate of spermatogenesis. We have investigated whether
there are differences in endogenous androgen production, of testicular and
adrenal origin, which may be related to the degree of suppression of
spermatogenesis. Thirty-three healthy Caucasian men were given weekly i.m.
injections of 200 mg testosterone oenanthate (TE), 18 became azoospermic,
while 15 remained oligozoospermic. Urinary excretion of epitestosterone, a
specific testicular product, was reduced to <10% of pretreatment values,
with no differences between the groups. Similar results were obtained for
other markers of testicular steroidogenesis. Urinary and plasma adrenal
androgens were also reduced during TE treatment: a statistically
significant decrease in both (P < 0.001 and P < 0.05 respectively)
was seen in the azoospermic but not oligozoospermic responders. These
results suggest that testicular steroidogenesis is decreased to <10% by
the administration of supraphysiological doses of exogenous testosterone.
Differences in the degree of ongoing steroidogenesis in the testis do not
appear to account for incomplete suppression of spermatogenesis, thus
differences in androgen metabolism may underlie this heterogeneous
response. A small but significant reduction in secretion of adrenal
androgens was also detectable, the relevance of which is unclear.
相似文献
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Applications of recombinant DNA to pathologic diagnosis 总被引:1,自引:0,他引:1
Recombinant DNA techniques are contributing to the understanding of the pathogeneses of genetic, neoplastic, and viral diseases, and are used in the diagnosis of certain genetic and viral diseases. Such techniques will have wider application in the future and will play an increasing role in the clinical laboratory. The technology of this field rests upon the cleavage of DNA by certain enzymes, restriction endonucleases, and upon the ability to locate specific sequences of nucleotides in a cleaved DNA sample by using known fragments of DNA ("probes") labeled with radioisotopes or biotin. To produce useful probes, one "clones" multiple copies of the same DNA fragment in bacteria. The use of DNA probes in the clinical laboratory is valuable in antenatal diagnosis, genetic counseling, and post-natal diagnosis of genetic diseases, especially hematologic diseases and inborn errors of metabolism. DNA probes can also be used to detect viral genetic material in clinical specimens. 相似文献
6.
Since exogenous hemin has been shown to exert a variety of stimulatory effects on erythroid cells, including the augmentation of hemoglobin synthesis, we determined its effect on early stages of erythroid development by employing clonal cells assays. The addition of hemin at a concentration of 2 X 10(-4) M to cultures of normal murine marrow substantially increased the observed number of primitive BFU-E, which was in contrast to its lack of an effect on more mature erythroid colony-forming cells. This cell-specific enhancement of primitive BFU-E resulted in marrow frequencies equivalent to or exceeding those reported in the presence of "burst-promoting activity." In the presence of hemin, the number of BFU-E was also observed to be linearly related to the number of cells plated at very low plating densities, and the cell titration curve was observed to extrapolate to the origin. The evidence suggests that hemin may be a primary growth regulator of early developmental stages of erythroid progenitor cells. 相似文献
7.
Sauls FC Stephens DB Caveny R 《Journal of the Mississippi State Medical Association》2000,41(8):684-688
Off-Pump Coronary Artery Bypass (OPCAB) allows myocardial revascularization without use of cardiopulmonary bypass and may be associated with fewer postoperative complications. A retrospective review was undertaken to assess the value of this new strategy in our surgical practice. The records of all our patients (n = 259) undergoing isolated coronary artery bypass (CAB) operations from January 1 through December 31, 1999, were reviewed (Table 1). Patient characteristics and comorbidities were similar in both groups with the exception of age and diabetes (Table 2). Mean operating room time, blood products transfused, morbidity, mortality, and length of stay (LOS) were all significantly less in the OPCAB group. We conclude that OPCAB techniques may offer significant benefits to our population of patients undergoing myocardial revascularization. 相似文献
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Katelynn Toomer Kimberly Sauls Diana Fulmer Lilong Guo Kelsey Moore Janiece Glover Rebecca Stairley Joyce Bischoff Robert A. Levine Russell A. Norris 《Anatomical record (Hoboken, N.J. : 2007)》2019,302(1):117-124
Mitral valve prolapse (MVP) affects 2.4% of the population and has poorly understood etiology. Recent genetic studies have begun to unravel the complexities of MVP and through these efforts, mutations in the FLNA (Filamin-A) gene were identified as disease causing. Our in vivo and in vitro studies have validated these genetic findings and have revealed FLNA as a central regulator of valve morphogenesis. The mechanisms by which FLNA mutations result in myxomatous mitral valve disease are currently unknown, but may involve proteins previously associated with mutated regions of the FLNA protein, such as the small GTPase signaling protein, R-Ras. Herein, we report that Filamin-A is required for R-Ras expression and activation of the Ras–Mek–Erk pathway. Loss of the Ras/Erk pathway correlated with hyperactivation of pSmad2/3, increased extracellular matrix (ECM) production and enlarged mitral valves. Analyses of integrin receptors in the mitral valve revealed that Filamin-A was required for β1-integrin expression and provided a potential mechanism for impaired ECM compaction and valve enlargement. Our data support Filamin-A as a protein that regulates the balance between Erk and Smad activation and an inability of Filamin-A deficient valve interstitial cells to effectively remodel the increased ECM production through a β1-integrin mechanism. As a consequence, loss of Filamin-A function results in increased ECM production and generation of a myxomatous phenotype characterized by improperly compacted mitral valve tissue. Anat Rec, 302:117–124, 2019. © 2018 Wiley Periodicals, Inc. 相似文献
10.
Chiang Jannifer O. Azevedo Rafael S. Justino Maria C. A. Matos Haroldo J. Cabeça Hideraldo L. S. Silva Sandro P. Henriques Daniele F. Silva Eliana V. P. Andrade Gabriela S. S. Vasconcelos Pedro FC. Martins Lívia C. Azevedo Raimunda S. S. 《Journal of neurovirology》2021,27(4):626-630
Journal of NeuroVirology - We describe two neurological cases of Oropouche virus infection in northern Brazil, where the virus is endemic but neglected as a pathogen. This study reiterates the... 相似文献