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Biomedical subjects

J G Houle

Publications and source records attributed to J G Houle.

6 recordsLinked to original sources
PubMed1985

Orchiopexy with a thimble.

The use of a thimble to facilitate scrotal fixation of the testis is described. We performed 52 orchiopexies in 48 children with cryptorchidism using this simple technique with excellent results.

Child, Preschool↗
PubMed1984

The regulation of ribosomal protein S-6 phosphorylation in Xenopus oocytes: a potential role for intracellular pH.

The intracellular pH of full-grown Xenopus oocytes increases from 7.2 to 7.6 in response to progesterone stimulation. Phosphorylation of the 40 S ribosomal protein S-6 increases six- to eightfold in these stimulated cells and this phosphorylation coincides with the intracellular alkalization. This is followed by a two- to threefold increase in the protein synthetic rate. Progesterone-treated cells cultured in choline chloride substituted Na-free medium fail to alkalize and S-6 is not phosphorylated. Weak bases, such as trimethylamine, methylamine, and procaine, artificially alkalize the cell cytoplasm and stimulate S-6 phosphorylation in medium containing or lacking sodium. The methylxanthine theophylline, suppresses S-6 phosphorylation and inhibits protein synthesis. This inhibition does not appear to involve cAMP. Rather, theophylline acidifies the oocyte cytoplasm. Thus, S-6 phosphorylation appears to be regulated by the intracellular pH of the cell. In addition, the level of protein synthesis in the oocyte seems to be correlated with the level of S-6 phosphorylation.

Animals↗
PubMed1984

The maturation response of stage IV, V, and VI Xenopus oocytes to progesterone stimulation in vitro.

Full-grown Xenopus oocytes, Stage VI (1200-1300 microns), undergo meiotic maturation when exposed to progesterone. Smaller stage IV (800 microns) and stage V (1000 microns) oocytes remain in prophase arrest when exposed to this steroid. The larger stage VI oocytes undergo an intracellular alkalization from 7.2 to 7.6, a six- to eightfold increase in the phosphorylation of the 40 S ribosomal protein S-6, and a two- to threefold increase in total protein synthesis when exposed to progesterone. It was found that 800- to 1000-microns oocytes do not undergo these physiological changes when exposed to progesterone. This lack of response could explain the failure of small oocytes to undergo germinal vesicle breakdown (GVBD). However, when stage IV and V oocytes were artificially alkalized to a pHi of 7.6 by the weak bases, trimethylamine, procaine, or methylamine, S-6 phosphorylation was stimulated four- to sixfold and protein synthesis was stimulated two- to threefold, but they still did not undergo GVBD. Stage IV and V oocytes are able to amplify MPF injected into their cytoplasm and undergo GVBD. Thus, 800- to 1000-microns oocytes appear to contain a store of inactive MPF in their cytoplasm. It seems that an additional physiological parameter(s), that is unique to steroid-treated stage VI oocytes, is responsible for activating this MPF which induces GVBD.

Animals↗
PubMed1983

Intracellular pH plays a role in regulating protein synthesis in Xenopus oocytes.

Full-grown Xenopus oocytes undergo meiotic maturation in response to progesterone stimulation. Using [14C]dimethyloxazolidine dione (DMO), we have measured a cytoplasmic alkalization in these oocytes starting at pH 7.14 +/- 0.17 during the germinal vesicle (GV) stage, and increasing to 7.56 +/- 0.14 at the time of germinal vesicle breakdown (GVBD). During this period, the rate of protein synthesis increases 2-fold from 18.9 +/- 3.1 to 37.7 +/- 8.8 ng/hr/oocyte. Artificial alkalization of GV stage oocytes to pHi 7.68 +/- 0.16, by exposure to the weak bases trimethylamine, methylamine, procaine, or imidazole, led to a 1.8-fold increase in the synthetic rate. Intracellular acidification from 7.5 back to 7.0 had no apparent effect on the elevated rate of protein synthesis following GVBD. Therefore, a cytoplasmic alkalization in the range of 7.5 to 7.6 seems to be one of the events that is necessary for initiating the increase in protein synthesis in maturing Xenopus oocytes; however, it does not appear that an elevated pHi is necessary to maintain the increased synthetic rate following GVBD.

Acetates↗