Testis human

ST6GalNAc II Sia(o2-6)[Gal(P 1 -3)]GalNAc-R chick testis human epithelial cells [611] [612] requires Gal( 31-3)GalNAc as substrate, does not act on GalNAc-R... 

Substrates Rat liver Human liver s Porcine testis Human placenta Rat brain/ Human leucocyte J... 

Testosterone, the principal male sex steroid hormone, is synthesized in five steps from cholesterol, as shown below. In the last step, five isozymes catalyze the 17/3-hydroxysteroid dehydrogenase reactions that interconvert 4-androstenedione and testosterone. Defects in the synthesis or action of testosterone can impair the development of the male phenotype during embryogenesis and cause the disorders of human sexuality termed male pseudohermaphroditism. Specifically, mutations in isozyme 3 of the 17/3-hydroxysteroid dehydrogenase in the fetal testis impair the for-... 

In addition, several other organs, like the heart, ovaty, amnion, chorion, decidua, testis, epididymis and prostate, have been reported to synthesize OT, suggesting a paracrine role for this hormone in these tissues. Ectopic AVP production by lung cancer cells or other neoplasms has been described in humans, leading to the syndrome of inappropriate antidiuretic hormone secretion. 

OTR is also expressed in male reproductive tissues, like testis, epididymis and in the prostate. OT increases the resting tone of prostatic tissue from guinea pig, rat, dog and human. The activation of these receptors could lead to the contraction of the prostate and the resulting expulsion of prostatic secretions during ejaculation. 

Giwercman A, Carlsen E, Keiding N, et al. 1993. Evidence for increasing incidence of abnormalities of the human testis A review. Environ Health Perspect Suppl 101 65-71. 

SHARPE R M, MARTIN B, MORRIS K, GREIG I, MCKINNELL, MCNEILLY A S, WALKER M (2002) Infant feeding with soy formula mflk effects on the testis and on blood testosterone levels in marmoset monkeys during the period of neonatal testicular activity. Human Reproduction. 17 1692-1703. 

A recent series of experiments with cats, chickens, or rats exposed to [uniformly labeled 14C-phenyl]-TOCP shows that a complex array of oxidized and dearylated metabolites are found in excreta and various tissues including the liver, kidney, testis, and brain (Abou-Donia et al. 1990a, 1990b Nomeir and Abou-Donia 1986 Somkuti and Abou-Donia 1990). Cats and chickens, like humans, are sensitive to TOCP-induced delayed neuropathy (Baron 1981). A similar array of oxidized and dearylated derivatives of tri-para-cresyl phosphate (but no cyclic metabolites) were identified by mass spectrometry in the urine and... 

M16. McCarrey, J. R., and Thomas, K., Human testis-specific PGK gene lacks introns and possesses characteristics of a processed gene. Nature 326,501-505 (1987). 

Gerard, CM, Molerau, C, Vassart, G, Parmentier, M. Molecular cloning of a human cannabinoid receptor which is also expressed in testis. Biochem J 1991 279 129-134. 

Following Smith (1984) I have argued that the risk of sperm warfare has helped to shape the evolution of just about every aspect of human sexuality - from testis size to penis shape, and from the wet sheet phenomenon to masturbation and the female orgasm (Baker and Beilis 1995 Baker 1996). 

Hours since last ejaculation (Jouannet et al. 1981) and testis size (Kim and Lee 1982 Harvey and May 1989) both show the expected positive relationships (Table 1). Chronic alcoholism has a major negative influence on semen quality (Gomathi et al. 1993), but small amounts of alcohol are associated with more sperm in masturbatory ejaculates (Gerhard et al. 1992), as in Table 1. Autopsy studies have shown that the number of sperm manufactured per day by human testes declines by about 5 million for every year of a man s life after the age of about 25 y (Neaves et al. 1984). The decline per insemination of about 13 million for each year of age found in the Manchester study matches this autopsy work well, being the decline expected if the interval between ejaculations were 2—3 days. 

In contrast to this ever-nearer dead-end for the direct investigation of ejaculates, the possibilities for investigating the way that testis size and symmetry influence male (and, for symmetry, female) reproductive strategy at different stages of their lives seem to be widening. There is still much more to discover about human copulation, masturbation and infidelity than is discussed in this interim description of the state-of-the-art. 

Diamond, J. M. (1986). Variation in human testis size. Nature. London 320, 488-489. 

Mailer, A. P. (1988a). Ejaculate quality, testis size and sperm competition in primates. Journal of Human Evolution 17,479-488. 

A new proteasome activator called PA200 was recently purified from bovine testis [156]. Human PA200 is a nuclear protein of 1843 amino acids that activates all three catalytic subunits with some preference for the PGPH active site. Homologs... 

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