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Biomedical subjects

E J Murray

Publications and source records attributed to E J Murray.

52 records · Page 3Linked to original sources
PubMed1982

The construction of cosmid libraries which can be used to transform eukaryotic cells.

Cosmid vectors have been developed which carry selective markers for growth in bacteria (beta lactamase gene) and animal cells (the Herpes Simplex virus thymidine kinase gene, the transposon Tn-5 aminoglycosyl 3' phosphotransferase gene and the E. coli guanine phosphoribosyltransferase gene). The design of the cosmids allows the exchange of the eukaryotic markers in recombinant cosmids. Human and mouse cosmid libraries containing DNA inserts of about 40kb have been generated by an improved method. Several clones from the human beta-globin locus were isolated. These cosmids transform mouse L cells at high efficiency in both circular and linear form. The newly introduced genes are expressed accurately in L cells.

Animals↗
PubMed1982

Removal of trace metals from culture media and sera for in vitro deficiency studies.

Culture media and sera contain substantial quantities of trace metals such as zinc and copper, so that they cannot be used for cell culture studies of trace metal deficiencies unless the element in question is first removed. By coupling the chelator iminodiacetate to an insoluble agarose matrix, we have been able to extract zinc selectively from both media and sera, without exposing cells directly to the chelator. The procedure reduced the zinc concentration of media to unmeasurably low levels, and serum zinc concentration by approximately 90%. The development of zinc deficiency in vitro was demonstrated by a reduced lymphocyte blastogenic response, which could be prevented by the addition of zinc to the extracted culture medium. The extraction procedure is potentially applicable to a range of trace elements (e.g., Zn, Cu, Mn, Fe) and to virtually any cell type that can be cultured.

Adult↗
PubMed1982

Mandibular bone turnover during calcium deficiency in the rat.

Bone resorption and deposition during calcium deficiency were compared in the mandible, femur, and vertebrae. While resorption did not differ markedly among the three sites, mineral deposition was lowest in the mandible, leading to a greater net loss of mineral than from femur or vertebrae.

Animals↗
PubMed1981

Turnover of bone zinc during normal and accelerated bone loss in rats.

The ability of the skeleton to serve as a reservoir of available zinc was investigated in weanling and 7-week-old rats. Bone turnover was measured by the loss of previously incorporated 3H-tetracycline (TC), in conditions of normal turnover accompanying growth or accelerated loss produced by calcium deficiency. The 4-week studies involved four experimental groups per age group (all combinations of high and low calcium, high and low zinc). By measuring loss of 3H-TC and whole bone (humerus) contents of Zn and Ca, it was possible to calculate the deposition and resorption of Zn and Ca during the experimental period. Several conclusions emerged from the study: 1) availability of Zn from the skeleton was dependent on the rate of bone resorption, but not on Zn status; 2) redeposition of Zn in the skeleton following resorption was extensive, and independent of the rate of bone mineral deposition; and 3) in Ca deficiency there was an increased deposition of Zn, suggesting a partial substitution of Zn for Ca in bone mineral. The results support the concept that the skeleton does not serve as a reservoir for Zn. Very little Zn is made available by bone resorption, and even then Zn is lost only in a passive manner that is dependent on, but does not influence, bone turnover. The availability of Zn from the skeleton is not mediated by Zn status.

Aging↗