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Biomedical subjects

J E Fox

Publications and source records attributed to J E Fox.

252 records · Page 14Linked to original sources
PubMed1971

The metabolism and biological activity of a 9-substituted cytokinin.

In order to test the metabolic stability of 9-substituted cytokinins, 6-benzylamino-9-methyl purine has been synthesized and labeled with (14)C in the 9-methyl carbon or doubly labeled with (14)C in the 9-methyl carbon and (3)H in the methylene moiety of the side chain. Although the 6-benzylamino-9-methylpurine is chemically stable, cytokinin-requiring tissues begin removing the 9-substituent in as little as 10 minutes. Among the various metabolic products is free benzylaminopurine. Thus, the biological activity of 9-substituted cytokinins could be accounted for by their conversion to the free base.

Journal Article↗
PubMed1966

Incorporation of a kinin, N, 6-benzyladenine into soluble RNA.

Kinin requiring tobacco and soybean tissues incubated on a medium containing N,6-benzyladenine-8-C(14) incorporated C(14) into several RNA components including adenylic and guanylic acids. About 15% of the label taken up by the tissues appeared in RNA while the remainder was distributed among several metabolites in the soluble, nonpolynucleotide fraction. Tissue grown on a kinin labeled in the side chain (N,6-benzyladenine-benzyl-C(14)) also incorporated a small, but nevertheless repeatable, amount of radioactivity into minor RNA components.Ultracentrifugation studies and methylated albumin chromatography indicated that the bulk of the label from benzyladenine-benzyl-C(14) is in soluble RNA. Approximately 50% of the C(14) in soluble RNA is in a component which has chromatographic properties like that of benzyladenine.It is suggested that the biological action of the kinins may hinge on their providing substituted bases in RNA in tissues which through differentiation no longer synthesize RNA-methylating enzymes. As an alternative it was hypothesized that a small amount of benzyladenine was incorporated into a m-RNA, acting there as a derepressing agent, perhaps by preventing its normal repressing function.

Journal Article↗
PubMedDate not supplied

Cytogenetic analysis of tissues from patients with familial paragangliomas of the head and neck.

BACKGROUND: Paragangliomas of the head and neck are slow-growing tumors that originate from neural crest cells. Between 7% and 9% of these tumors have a familial occurrence. The suspected gene for familial paragangliomas (FP) is transmitted with an autosomal dominant mode of inheritance with incomplete penetrance, and appears to exhibit genomic imprinting. It has been demonstrated by family studies that individuals who inherit the gene(s) from their father will develop the disease. Through linkage analysis, the gene(s) for FP has been postulated to be located on the long arm of chromosome 11. The discovery of many different genes has been elucidated through the cytogenetic analysis of affected individuals who carry specific chromosome aberrations. This project was designed to look for chromosome abnormalities in several second-generation family members to further assist in the localization of the gene(s) for FP. METHODS: This study involved the cytogenetic evaluation of lymphocytes, fibroblasts, and tumor cells of several second-generation family members from a three-generation family with FP of the head and neck to look for chromosome abnormalities generally, and for abnormalities of chromosome 11 specifically. Standard cytogenetic techniques were used for lymphocyte and fibroblast cultures. Tumor cells were cultured in a collagen matrix with F12 medium supplemented with 3% L-glutamine and 10% fetal calf serum. RESULTS: There were no detectable abnormalities of chromosome 11 in any of the cells. However, nonrandom abnormalities of chromosomes 5 and 7 were seen in some of the tumor cells of one FP patient. To our knowledge, this is the first article which demonstrated the ability to successfully culture FP of the head and neck.

Adult↗
PubMedDate not supplied

Characterization of neurotensin binding to rat gastric smooth muscle receptor sites.

The binding of monoiodo 125I-Trp11-neurotensin to purified rat gastric fundus smooth muscle plasma membranes was characterized. Specific binding of ligand in subcellular fractions from rat fundus smooth muscle showed a distribution that paralleled that of several plasma membrane marker enzymes. 125I-Trp11-neurotensin binding to smooth muscle plasma membranes at 25 degrees C was maximal at 30 min, reversible and saturable. Scatchard analysis of equilibrium data indicated the existence of two classes of binding sites with dissociation constants (Kd) of 56 pmol and 1.92 nM, and corresponding binding capacities (Bmax) of 6.6 fmol/mg and 11.4 fmol/mg of membrane protein. Analogues and fragments of neurotensin competed for 125I-Trp11-neurotensin binding with a rank order of potency similar to that previously reported for their contracting effect in rat fundus strips. Na+ decreased in a concentration dependent manner the binding of labelled ligand to the high affinity site. At 100 mM, Na+ induced a 6-fold increase in the IC50 of neurotensin for inhibition of 125I-Trp11-neurotensin binding. At this concentration of Na+, the IC50 for neurotensin was 1 nM, a value close to the Kd of the low affinity site.

Amino Acid Sequence↗
PubMedDate not supplied

Actions of galanin fragments on rat, guinea-pig, and canine intestinal motility.

The 1-20 fragment of synthetic porcine galanin, prepared by tryptic digestion of the intact molecule, was equipotent to synthetic porcine galanin 1-29 in the smooth muscle actions of exciting the rat jejunal longitudinal muscle in vitro and inhibiting circular muscle contractions of the canine small intestine in vitro and in vivo, but was less potent in inhibiting nerve-stimulated contractions of the guinea-pig taenia coli. Fragment 21-29 was effective at high doses only in the canine ileum. Activity of galanin 1-11 was greatly reduced in the dog in vivo. These results may reflect species or cell type differences.

Animals↗
PubMedDate not supplied

The actions of neurokinins and substance P in canine pylorus, antrum and duodenum.

Analogues highly selective for receptors for substance P [beta-Ala4,Sar9,Met(02)11]-SP(4-11), for neurokinin A, [Nle10]-NKA(4-10), and for neurokinin B, [beta-Asp4,MePhe7]-NKB(4-10), were administered intraarterially before and after atropine or tetrodotoxin, to characterize the locations on nerve and muscle of the different receptor subtypes in the canine antrum, pylorus and duodenum. Circular muscle strips from each region were also studied in vitro. The NK-2 receptors in the antrum and the pylorus were located postsynaptically on smooth muscle. The NK-3 receptors, on the other hand, were located on neuronal sites in the antrum and duodenum. NK-1 receptors were located on neuronal and nonneuronal sites in the antrum, pylorus and duodenum. Only nonneural receptors could be activated in vitro.

Animals↗
PubMedDate not supplied

Maternal practice and attitudes toward breastfeeding.

An age-graded sample of 411 New York City mothers is assessed to evaluate the direction and amount of change in incidence of breastfeeding. Social and demographic factors are considered and are found to have little trend effect. This limited sample fails to indicate any increase in breastfeeding in the 1970s, as compared to earlier decades. However, maternal attitudes are more positive toward breastfeeding than toward bottlefeeding; and some ethnic, economic, and sociocultural factors do affect decision to breastfeed.

Adolescent↗