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Biomedical subjects

K Hardy

Publications and source records attributed to K Hardy.

118 records · Page 7Linked to original sources
PubMed1978

Immunological properties of fractionated avian erythroid nuclei.

Chicken reticulocyte (polychromatic primitive erythrocyte) and erythrocyte chromatin was fractionated by ultrasound shearing and salt precipitation into three fractions differing in their activities to support the in vitro RNA synthesis. The transcriptionally active fraction of chicken reticulocyte chromatin which represented only about 0.5% of the total nuclear DNA contained essentially all the chromatin-associated endogenous RNA. Approximately 2% of this endogenous reticulocyte RNA hybridized to globin cDNA probe and could be translated in vitro into polypeptides which coelectrophoresed with the in vitro translation product of isolated chicken globin mRNA or chicken globin marker. Each of the three fractions had a characteristic distribution of chromosomal proteins and endogenous RNA. Polyacrylamide gel electrophoresis of the chromosomal proteins showed differences in their distribution among individual fractions of the same cell type and among corresponding fractions of reticulocyte or erythrocyte chromatin. Antisera produced against dehistonized reticulocyte chromatin were specific for reticulocyte but not erythrocyte chromatin. When reacted with each of the differentially templating chromatin fractions, it was found that reticulocyte-specific antibodies were highly reactive with the template-active fraction of reticulocytes, but essentially nonreactive with any other reticulocyte fraction. This same antiserum was not significantly reactive toward any erythrocyte fraction. The antigenicity of the template-active fraction of reticulocytes was abolished after pronase or DNase II digestion, but only partially diminished after DNase I digestion.

Animals↗
PubMed1977

Studies of the metabolic fate of p-hydroxybenzoic acid in male and female cats.

Metabolic studies conducted on p-hydroxybenzoic acid orally administered at dose levels of 13 and 26 mg/kg to male and female cats have shown that the compound is rapidly excreted in the urine exclusively in the form of the glycine conjugate p-hydroxyhippuric acid. Similar results were obtained following either single administration or 7-day treatment. The metabolite in the urine was characterised by thin-layer chromatography, amino acid analysis and mass spectrometry.

Amino Acids↗
PubMedDate not supplied

HPRT-deficient (Lesch-Nyhan) mouse embryos derived from germline colonization by cultured cells.

Embryonal stem (ES) cell lines, established in culture from peri-implantation mouse blastocysts, can colonize both the somatic and germ-cell lineages of chimaeric mice following injection into host blastocysts. Recently, ES cells with multiple integrations of retroviral sequences have been used to introduce these sequences into the germ-line of chimaeric mice, demonstrating an alternative to the microinjection of fertilized eggs for the production of transgenic mice. However, the properties of ES cells raise a unique possibility: that of using the techniques of somatic cell genetics to select cells with genetic modifications such as recessive mutations, and of introducing these mutations into the mouse germ line. Here we report the realization of this possibility by the selection in vitro of variant ES cells deficient in hypoxanthine guanine phosphoribosyl transferase (HPRT; EC 2.4.2.8), their use to produce germline chimaeras resulting in female offspring heterozygous for HPRT-deficiency, and the generation of HPRT-deficient preimplantation embryos from these females. In human males, HPRT deficiency causes Lesch-Nyhan syndrome, which is characterized by mental retardation and self-mutilation.

Adenine Phosphoribosyltransferase↗
PubMedDate not supplied

Foetal metabolism, placental transfer and origin of gastrin releasing peptide in the sheep.

1. Plasma gastrin releasing peptide (GRP) is elevated in the foetal and maternal circulations of pregnant sheep. To determine the mechanisms for this increase the synthesis, secretion rate, metabolism and placental transfer of GRP were measured. 2. Foetal metabolic clearance rate of GRP was significantly increased (P < 0.05) compared to the non-pregnant ewe (19.9 +/- 2.6 (s.e.m.) and 11.8 +/- 2.0 mL/min per kg, respectively). Production rate of GRP in the foetus was four-fold higher than in the non-pregnant ewe reflecting the combination of the increased basal concentration and metabolic clearance rate in the foetus. 3. Infused GRP did not cross the placenta. However, endogenous GRP was higher in the umbilical vein than in the umbilical artery, suggesting a uteroplacental origin for some of the GRP in the foetal circulation. 4. Gastrin releasing peptide mRNA was synthesized in the pregnant endometrium with lower amounts found in the pregnant myometrium. No GRP mRNA was detected in the amnion or chorioallantois. 5. The results show that the previously reported increase in foetal concentration of GRP is from foetal and uteroplacental sources and is not a result of immaturity of clearance mechanisms but rather from an increased production of GRP. With the demonstration that the uteroplacental unit synthesizes and stores GRP, additional studies on the regulation of GRP production from these sources were warranted.

Animals↗