Search PubMed⌕ Search

Biomedical subjects

M L Allen

Publications and source records attributed to M L Allen.

At least 73 records · Page 4Linked to original sources
PubMed1986

Oral acyclovir for episodic treatment of recurrent genital herpes. Efficacy and safety.

This multicenter double-blind study of 157 patients was designed to evaluate the safety and efficacy of a new dosage regimen of oral acyclovir (800 mg twice a day for 5 days) for the treatment of recurrent genital herpes. The new regimen was compared with the standard dosage of 200 mg given five times a day to patients treated for three consecutive episodes (one episode with physician-initiated therapy and two with patient-initiated therapy) and followed up for three untreated episodes. The new regimen was well tolerated and effective. In male patients it may be more effective than the standard regimen of 200 mg given five times a day to treat vesicles that are already present.

Acyclovir↗
PubMed1986

Immunodissection and culture of rabbit cortical collecting tubule cells.

A mouse monoclonal antibody designated IgG3(rct-30) has been prepared that reacts specifically with an antigen on the surface of all cells comprising the cortical and medullary rabbit renal collecting tubule including the arcades. Plastic culture dishes coated with IgG3(rct-30) were used to isolate collecting tubule cells from collagenase dispersions of rabbit renal cortical cells by immunoadsorption. Typically, 10(6) rabbit cortical collecting tubule (RCCT) cells were obtained from 5 g of renal cortex (2 kidneys). Initial purity was greater than 96% based on immunocytofluorescent staining with three different anti-collecting tubule antibodies. Between 20 and 30% of the RCCT cells were reactive with peanut lectin suggesting that RCCT cells are a mixture of principal and intercalated cells. Approximately 10(7) RCCT cells were obtained after 4 to 5 days in primary culture. Moreover, RCCT cells continued to proliferate after passaging with a doubling time of approximately 32 h. RCCT cells passaged once and then cultured 4-5 days were found 1) to synthesize cAMP in response to arginine vasopressin (AVP), prostaglandin E2 (PGE2), isoproterenol, and parathyroid hormone, but not calcitonin, prostaglandin D2, or prostaglandin I, and 2) to release PGE2 in response to bradykinin but not arginine vasopressin or isoproterenol. Our results indicate that cultured RCCT cells retain many of the hormonal, histochemical, and morphological properties expected for a mixture of principal and intercalated rabbit cortical collecting tubule epithelia. RCCT cells should prove useful both for studying hormonal interactions in the cortical collecting tubule and as a starting population for isolating intercalated collecting tubule epithelia.

Animals↗
PubMed1986

Dynamics of digestion in cattle, sheep, goats and deer.

Four experiments were conducted to study factors affecting digestibility of forages in cattle, sheep, goats and white-tailed deer. In a series of digestion trials (Exp. 1), the dry matter digestibility of a moderately high fiber diet was greater in cattle than in deer. Digestibilities of the diet in sheep and goats were intermediate and not different from either extreme. In a second series of trials (Exp. 2), relative organic matter digestibilities were for goats more than sheep more than deer. However, in Exp. 2, intake in goats was very low and digestibility appeared to be positively related to retention time and inversely related to turnover rate. Results of three trials (Exp. 3) suggested that rate of digestion was related more to diet than to the animal species consuming the diet. In grazing animals (Exp. 4), goats digested a smaller percentage of consumed material than either cows or sheep during three of four seasons even though diets were of similar in vitro digestibility. This difference was related to a faster turnover and shorter retention time in goats. These data support the concept that there are species differences in gastrointestinal dynamics which may be which may be important determinants of adaptability to grazing conditions.

Animal Feed↗
PubMed1985

Automated analysis and survival selection of anchorage-dependent cells under normal growth conditions.

An instrument is described that can automatically analyze and select for a subpopulation of anchorage-dependent cells in tissue culture. Cells that label with fluorescently tagged antibodies or demonstrate structural variations are saved from exposure to a destructive high-intensity argon laser beam. The surviving population may then be cloned. The cell selection may occur in a tissue culture plate or in a microflow incubator which is designed to maintain a constant flow of media at 37 degrees C across cells growing on a glass coverslip. This incubator sits on an inverted microscope which focuses the laser beam to a diameter as small as 1 micron. A high-speed computer-controlled two-dimensional stage moves the cells past the beam for analysis, the results of which determine the fate of each cell: whether it is to be destroyed by radiant energy or selected for survival and subsequent proliferation. Another selection strategy performed by the instrument involves growing the cells on a thin, blackened polyester film which can be cut by the argon laser beam. Cells selected for cloning are then circumscribed. The heat of cutting welds the circumscribed film to a plastic coverslip surface or tissue culture chamber bottom. Nonselected cells may be removed by pulling the unattached polyester sheet from the attachment surface. The selected cells remain on polyester film disks welded to the plastic. Selections may be done automatically under computer control or manually by operator direction of stage movements. This instrument extends the art of automated cell selection and analysis to normal cell lines that must maintain cell-substratum contact (anchorage dependence) for differentiated cell function, e.g., neurons, fibroblasts, or kidney cells.

Cell Adhesion↗
PubMed1985

The effects of swallowing frequency and transdermal scopolamine on esophageal acid clearance.

Fourteen volunteers were studied on two occasions to assess the effect of swallowing frequency on acid clearance time. The experimental protocol consisted of two trials of infusion of 15 ml of 0.1 N HCl into the distal esophagus. One trial required swallowing every 30 s for 10 min. The other trial involved an initial rapid swallowing rate (seven swallows in the 1st min) with a gradual predetermined decline in rate. This procedure was repeated 12 h after application of a transdermal scopolamine patch. Baseline clearance times for rapid and slow swallowing were not significantly different. The anticholinergic drug significantly prolonged the clearance times for both rapid and slow swallowing. Under baseline conditions, sequential swallows (after the first three to four swallows) produced a significant rise in pH until the clearance criterion of pH 4.0 was reached. This effect was abolished with the anticholinergic drug. These results support a two-stage model of acid clearance with initial volume clearance and subsequent salivary buffering of residual intraesophageal acid.

Administration, Topical↗
PubMed1983

Bimodal distribution of the prostaglandin I2 synthase antigen in smooth muscle cells.

Vascular and nonvascular smooth muscles in 12 different organs from the gastrointestinal, respiratory, and urogenital tracts of the rabbit, cow, dog, sheep, pig, and rat were examined for prostaglandin I2 (PGI2) synthase immunoreactivity by indirect immunocytofluorescence using monoclonal antibodies against the enzyme. Each of 35 different smooth muscle layers tested stained for the PGI2 synthase antigen except the circular smooth muscle of the rabbit large intestine. Interestingly, PGI2 synthase-positive fluorescent staining of smooth muscle was always observed to be associated with both the nuclear and plasma membranes. Our results indicate that most smooth muscle, both vascular and nonvascular, has the capacity to synthesize PGI2. Moreover, the fact that the PGI2 synthase antigen is associated with at least two different organelles in each cell suggests that there are two independent PGI2-synthesizing systems in smooth muscle; one on the nuclear membrane, and one on the plasma membrane. PGI2 formed at these different sites may subserve different functions within the same cell.

Animals↗
PubMed1982

Interrelationships among prostaglandins, vasopressin and cAMP in renal papillary collecting tubule cells in culture.

To determine the influence of prostaglandins on cAMP metabolism in renal papillary collecting tubule (RPCT) cells, intracellular cAMP levels were measured after incubating cells with prostaglandins (PGs) alone or in combination with arginine vasopressin (AVP). PGE1, PGE2 and PGI2, but not PGD2 or PGF2 alpha, increased intracellular cAMP concentrations. At maximal concentrations (10(-5) M) the effects of PGE2 plus PGI2 (or PGE1), but not of PGI2 plus PGE1, were additive suggesting that at least two different PG receptors may be present in RPCT cell populations. Bradykinin treatment of RPCT cells caused an accumulation of intracellular cAMP which was blocked by aspirin and was quantitatively similar to that observed with 10(-5) M PGE2. PGs, when tested at concentrations (e.g. 10(-9) M) which had no independent effect on intracellular cAMP levels, did not inhibit the AVP-induced accumulation of intracellular cAMP in RPCT cells. These results indicate that PGs do not block AVP-induced accumulation of intracellular cAMP in RPCT cells at concentrations of PGs which have been shown to inhibit the hydroosmotic effect of AVP on perfused collecting tubule segments. However, at higher concentrations of PGs (e.g. 10(-5) M), the effects of AVP plus PGE1, PGE2, PGI2 or bradykinin on intracellular cAMP levels were not additive. Thus, under certain conditions, there is an interaction between PGs and AVP at the level of cAMP metabolism in RPCT cells.

1-Methyl-3-isobutylxanthine↗
PubMed1978

Continual sexual receptivity in the female chimpanzee (Pan troglodytes).

Daily observations during a 5-year period showed that the mean frequencies of copulation per day during various sexual states of the female chimpanzee were almost identical, except for during maximum tumescence and lactation. The mean frequency of observed copulation peaked during maximum tumescence and was lowest during lactation.

Animals↗