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Biomedical subjects

A Heyl

Publications and source records attributed to A Heyl.

7 recordsLinked to original sources
PubMed2001

A transcript encoding a nucleic acid-binding protein specifically expressed in maize seeds.

A cDNA clone has been obtained for a low-abundance, seed-specific mRNA that encodes a polypeptide which defines a novel family of plant proteins with some similarities to the DnaJ class of molecular chaperones. The MEM1 (Maize Endosperm Motif binding protein) protein is capable of binding to the endosperm motif and activating transcription in the yeast one-hybrid system. Recombinant MEM1 was shown to bind in vitro to nucleic acids, with a preference for RNA over DNA. MEM1 is capable of forming homodimers, a property that is dependent on a domain close to the C-terminus of the protein. The protein is expressed in mid- to late-term endosperm cells. Subcellular fractionation and size fractionation under non-denaturing conditions indicate that the protein is present in the cytosol of endosperm cells. Possible roles of MEM1 in endosperm and protein body development are discussed.

Amino Acid Sequence↗
PubMed1989

Iatrogenic chylous ascites: operative or conservative approach.

Postoperative chylous ascites is a rare complication of aortic surgery. Two patients are presented with postoperative chylous ascites after abdominal aortic surgery. The value of either conservative management or an operative approach or peritoneo-venous shunting is discussed.

Aorta, Abdominal↗
PubMed1987

An evaluation of the anti-androgen effects associated with H2 antagonist therapy.

The effect of two different H2-receptor antagonists, nizatidine and cimetidine, on sperm counts and hypothalamic-pituitary-gonadal function as determined by responses to provocative gonadotropin releasing factor, GnRH, thyrotropin releasing factor, TRH, and clomiphene were compared to those of men receiving placebo medication. All subjects studied gave informed written consent and were greater than 18 but less than 55 years of age. Sperm concentrations in collected semen specimens, and GnRH and TRH responses before and after 6 weeks of drug exposure were assessed as were the gonadotropin responses to clomiphene while on the drug for an additional 3 weeks. All had normal sperm concentrations and hormone levels before drug exposure and normal responses to both GnRH and TRH. Following drug exposure, the LH response to GnRH and the growth hormone, prolactin, TSH and T4 responses to TRH were similar to those obtained prior to drug use. Sperm concentrations were unchanged in both placebo and nizatidine exposed men, but were significantly reduced (p less than 0.05) in the cimetidine exposed men. Based on these data, nizatidine does not appear to influence hormone function or fertility.

Adolescent↗
PubMedDate not supplied

Flamelet modeling of NO formation in laminar and turbulent diffusion flames.

The applicability of the laminar flamelet concept for the formation and destruction of nitric oxides in laminar and turbulent diffusion flames has been studied. In a first step, temperatures and species concentrations in an axisymmetric laminar diffusion flame have been calculated (i) by solving the detailed conservation equations and (ii) by applying the laminar flamelet concept. The main purpose of this step was the identification of differences between results from both approaches. It turned out that for highly temperature sensitive or relatively slow chemical processes, the inclusion of the full range of the prevailing scalar dissipation rates plays a major role for the calculated species concentrations. This behavior is obvious from the concept of the laminar flamelet model, where the scalar dissipation rate can be discussed in terms of the reciprocal of a residence time for attaining chemical equilibrium. In a second step, flamelet modeling of NOx formation was extended to a turbulent hydrogen diffusion flame. In both the steps, the flow fields of the flames were calculated by solving the Navier-Stokes equations in axisymmetric formulation using the SIMPLER algorithm. For the turbulent flow, Favre-averaged equations have been used and turbulence was modeled with the standard k-epsilon model including a correction term for axisymmetric systems. The averaging of the species concentrations was accomplished with presumed shape probability density functions (pdfs). The pdf of the mixture fraction was described with a beta-function whereas that of the scalar dissipation rate was assumed to be log-normal. Buoyancy effects have been taken into account. The calculated temperatures and concentrations were compared with data from different experiments.

Journal Article↗