Search PubMed⌕ Search

Biomedical subjects

J A Phillips

Publications and source records attributed to J A Phillips.

At least 181 records · Page 10Linked to original sources
PubMed1986

Pedigree analysis of the 5' flanking region of the insulin gene in familial diabetes mellitus.

Non-insulin-dependent diabetes mellitus (NIDDM) has been reported to be associated with an insertion polymorphism in the 5' flanking region of the human insulin gene. We have attempted to examine linkage of this polymorphism to the phenotype of NIDDM by studying multiple pedigrees. We evaluated 142 individuals (120 white, 22 black), 80 of whom were from 7 pedigrees (5 white, 2 black) ranging in size from 4 to 37 members. Of these, 52 subjects had NIDDM, 10 had insulin-dependent diabetes mellitus (IDDM), and 80 were nondiabetics (ND). DNA was extracted from leukocytes and after digestion with Sst 1, and electrophoresis, the DNA was blotted to nitrocellulose filters and hybridized to a alpha 32P-labeled insulin gene probe. Two alleles of 6.0 and 7.6 kb in size were detected, the latter corresponding to the common previously described insertion polymorphism. In these families, the 7.6 kb allele occurred in 32 of 57 ND, 3 of 5 IDDM, and 10 of 18 NIDDM (P = 0.98). When sibships were analyzed the 7.6 kb allele occurred in 6 of 13 ND, 3 of 5 IDDM, and 8 of 12 NIDDM (P = 0.58). In examining 72 unrelated subjects, including 12 spouses from the pedigrees, the 7.6 kb allele was documented in 16 of 36 ND, 1 of 5 IDDM, and 16 of 31 NIDDM (P = 0.59). In these individuals and in the multiple families studied the insertion polymorphism flanking the insulin gene showed Mendelian inheritance and assorted independently of the phenotype of diabetes mellitus.

Adolescent↗
PubMed1986

Epithalamus of the nine-banded armadillo, Dasypus novemcinctus.

The epithalamus of embryonic, neonatal and adult nine-banded armadillo (Dasypus novemcinctus) was examined for evidence of pineal-like tissue. The evagination of the diencephalic roof (the anlage of the epiphysis) was not found in any embryonic specimens. In the adult brain, the epithalamus is dominated by the sub-commissural organ (SCO) which is surrounded entirely by the posterior commissure. At the most caudal aspect of the SCO, previous investigators have observed pineal-like tissue. Using pineal-specific staining techniques however, we found no evidence of this tissue. Because the armadillo produces melatonin in a rhythmic manner, exhibits exacting circadian rhythms, and shows altered rhythms when exposed to exogenous melatonin, we believe other organs, perhaps the retina or Harderian gland, must be involved in maintaining the coordinated melatonin titer.

Animals↗
PubMed1986

Kinin-induced prostaglandin release in rat colon does not display serosal/mucosal 'sidedness' after epithelial removal.

Release of prostaglandin E2 (PGE2) from rat colon in response to 1 microM lysylbradykinin (LBk) displayed 'sidedness' in preparations with an intact epithelial cell layer (PGE2 release, sensitivity to LBk and inhibition by indomethacin all occurred on the serosal side only). Preparations with histologically-verified removal of the epithelial layer and which were impermeable to prostaglandins (i.e. intact) continued to demonstrate LBk-induced PGE2 generation, but this and indomethacin inhibition did not display sidedness. The results show that kinin-induced PGE2 derives principally from cells in the lamina propria and not from the epithelial cells as previously supposed, and that the apparent sidedness of LBk responsiveness, PGE2 generation and its inhibition by indomethacin results from the barrier property of the epithelial cells and is not indicative of an asymmetric response.

Animals↗
PubMed1986

Tissue and gene specific hypomethylation of the human parathyroid hormone gene: association with parathyroid hormone gene expression in parathyroid glands.

An association between decreased cytosine methylation at specific sites adjacent to or within eukaryotic genes and increased gene expression has been described. To determine if tissues secreting PTH show hypomethylation within the vicinity of the PTH gene, we compared the degree of cytosine methylation in DNA from parathyroid glands and control tissues (leukocytes, anterior pituitary, posterior pituitary, and placenta). We digested DNA with HpaII (which cleaves only unmethylated CCGG sequences) and MspI [which cleaves CCGG and C 5-methyl cytosine GG], hybridized the DNA fragments to a PTH complementary DNA probe, and scanned autoradiograms of Southern blots. After MspI digestion all tissues yielded equivalent amounts of a single hybridizing fragment of 6.7 kilobases. The degree of hypomethylation at sites within and flanking the PTH gene was determined as the ratio of the amount of hybridizing fragments obtained by methylation-sensitive digestion (HpaII) relative to methylation-insensitive digestion (MspI). DNA from all parathyroid glands showed significantly greater hypomethylation of the PTH gene than did DNA from control tissues that did not express the PTH gene. Despite variability in the levels of secretory activity of the different parathyroid glands, we found no significant differences in the degree of hypomethylation of the PTH gene. In contrast to the PTH gene studies, hypomethylation was not seen using GH probe on the same blots. Our findings thus suggest that tissue and gene specific hypomethylation of the PTH gene is associated with expression of the gene.

Adenoma↗
PubMed1986

Growth hormone deficiency due to GH-N gene deletion in an Austrian family.

An 11 year old Austrian boy with isolated growth hormone deficiency type I A is described. On institution of GH therapy at the age of 2 2/12 years there was only a short growth response and anti-GH-antibodies with high binding capacity were detected, and growth was inhibited. Examination of the nuclear DNA by restriction endonuclease analysis demonstrated a defect of the GH-N gene in the patient. The results suggest the deletion in this Austrian family is different from that seen in other patients. The parents were heterozygous for the deletion and had a subnormal GH response to stimulation with arginine, but their somatomedin-C concentrations and their heights were normal. The patients' sister was of normal height, hormone analyses were normal, and the GH-N gene was not affected.

Antibodies↗
PubMed1985

Huntington's disease: two families with differing clinical features show linkage to the G8 probe.

To test the hypothesis that interfamily variability in Huntington's Disease (HD) is due to mutation at different loci, linkage analysis was undertaken in two large HD kindreds that differed in ethnicity, age-at-onset, and neurologic and psychiatric features. Both families showed linkage of the HD locus to the G8 probe. Several recombinants were documented in each family, and the best estimate of the recombination fraction for the two families was 6 percent with a 95 percent confidence interval of 0 to 12 percent. Although the data support the existence of a single HD locus, use of the G8 probe for presymptomatic testing in these kindreds would have resulted in a 12 percent error rate in genotype assignment at the HD locus.

Chromosomes, Human, 4-5↗
PubMed1985

The natural history of familial hypopituitarism.

Familial hypopituitarism in the Hutterite Brethren is an autosomal recessive disorder involving sequential loss of anterior pituitary tropic hormones. Five individuals from two closely related families have been followed for 19 years. Both families are well integrated into the Hutterite community. Three sibs elected not to be treated with growth hormone and sex steroids. These sibs developed growth hormone and gonadotropin deficiency in the first decade of life, with subsequent loss of TSH function and finally ACTH deficiency in the third decade. The pattern of hormone loss differed in the second family, in that deficiency of growth hormone, gonadotropins, and TSH was evident in the first decade. A third family has been reported to have the same disorder and is from a different endogamous subdivision from that of the two families described here. Genealogical analysis of the three families shows that there are four ancestral couples common to the six parents. Thus all affected individuals are likely to be identical by descent for the same ancestral allele. The gene for hypopituitarism is not closely linked to the gene for growth hormone nor to the HLA region.

Chromosomes, Human, 16-18↗
PubMed1985

A linkage map of three anonymous human DNA fragments and SOD-1 on chromosome 21.

Using DNA polymorphisms adjacent to single-copy genomic fragments derived from human chromosome 21, we initiated the construction of a linkage map of human chromosome 21. The probes were genomic EcoRI fragments pW228C, pW236B, pW231C and a portion of the superoxide dismutase gene (SOD-1). DNA polymorphisms adjacent to each of the probes were used as markers in informative families to perform classical linkage analysis. No crossing-over was observed between the polymorphic sites adjacent to genomic fragments pW228C and pW236B in 31 chances for recombination. Therefore, these fragments are closely linked to one another (theta = 0.00, lod score = 6.91, 95% confidence limits = 0-10 cM) and can be treated as one 'locus' with four high-frequency markers. There is a high degree of non-random association of markers adjacent to each of these two probes which suggests that they are physically very close to one another in the genome. The pW228C - pW236B 'locus' was also linked to the SOD-1 gene (theta = 0.07, lod score = 4.33, 95% confidence limits = 1-20 cM). On the other hand, no evidence for linkage was found between the pW228C-pW236B 'locus' and the genomic fragment pW231C (theta = 0.5, lod score = 0.00). Based on the fact that pW231C maps to 21q22.3 and SOD-1 to 21q22.1, we suggest that the pW228C-pW236B 'locus' lies in the proximal long arm of chromosome 21. These data provide the outline of a linkage map for the long arm of chromosome 21, and indicate that the pW228C-pW236B 'locus' is a useful marker system to differentiate various chromosome 21s in a population.

Alleles↗
PubMed1985

Genetic analysis of carbamyl phosphate synthetase I deficiency.

Carbamyl phosphate synthetase I deficiency (CPSD) is an autosomal recessive disorder of ureagenesis characterized by hyperammonemic coma in the neonatal period. To study the genetic basis of CPSD we have performed a molecular analysis of the CPS I genes in CPSD patients from six unrelated families. Using a cDNA probe for the human CPS I gene and restriction endonuclease mapping techniques, we observed no abnormality in the number of size of the hybridizing DNA fragments from the seven affected individuals examined. These findings suggest that no gross alteration affected the CPS I genes. We did detect a frequent restriction fragment length polymorphism (RFLP) at the CPS I locus which we employed as a linkage marker. Our results suggest the polymorphic CPS I restriction fragments cosegregate with the CPSD phenotype, and that linkage disequilibrium exists between the CPSI RFLPs studied and the affected alleles. The RFLPs described may enable prenatal detection of CPSD in families where the coupling phases between CPSD alleles and RFLPs can be determined.

Alleles↗
PubMed1985

A study of restriction fragment length polymorphisms at the human alpha-1-antitrypsin locus.

A cloned cDNA for alpha-1-antitrypsin (alpha-1-AT) was selected from a human liver cDNA library. The identity of the clone was established by hybrid-selected translation and partial DNA sequencing. The cDNA was used as a probe to search for restriction site polymorphisms (RSPs) near the alpha-1-AT gene. Only two RSPs were found using 29 different restriction enzymes. Each of these polymorphisms resulted from the loss of a restriction site, one for EcoRI and the other for Taq I. The frequency of polymorphic restriction was calculated to be 1.1% to 2.6% of all sites tested, a figure lower than the 9.3% value observed for 12 RSPs in the human beta-globin gene cluster. Since the corresponding figure for detectable polymorphisms at the alpha-1-AT locus at the protein level is 12%, restriction enzymes are comparatively inefficient in detecting genetic variability. The basis of this inefficiency was studied by computing the nucleotide diversity from the RSP data. On the average, one in 500 to 1000 bases is polymorphic around the alpha-1-At locus. This value is comparable to that which we have calculated for the human beta-globin gene cluster and the human growth hormone gene cluster (both one in 500). These data demonstrate the limited usefulness of linked RSPs for genetic linkage studies at the alpha-1-AT locus.

Base Sequence↗
PubMed1985

Chromosomal assignment of human sequences encoding arginine vasopressin-neurophysin II and growth hormone releasing factor.

Complementary DNA clones encoding bovine vasopressin and human pancreas growth hormone releasing factor have been used to map homologous sequences in the human genome. Assignment of both cloned sequences to human chromosome 20 was accomplished by hybridization of insert DNAs to a panel of human-rodent somatic cell hybrids. Both these probes have been used to examine the structure of their respective genes in DNA from various individuals. No restriction fragment variants for growth hormone releasing factor have yet been found. Analysis of populations for restriction fragment length polymorphisms associated with disease states involving arginine vasopressin is underway.

Animals↗
PubMed1985

Diagnosis of human endocrine disorders using recombinant DNA techniques.

In this chapter we have reviewed several present and potential examples of DNA studies of hereditary endocrine disorders of humans. For the former, recombinant DNA studies have provided insights into the location and types of molecular derangements underlying these diseases. The gene alterations detected have in turn explained the aetiology of quantitative or qualitative alterations in the hormone product. The same methods used in these studies should be applicable to determining the aetiology of many other genetic disorders that affect these, as well as other, hormones for which specific DNA probes are or will become available.

Arginine Vasopressin↗
PubMed1985

Highly potent inhibition of prostaglandin 15-hydroxydehydrogenase in-vitro and of prostaglandin inactivation in perfused lung by the new azobenzene analogue, Ph CL 28A.

The new azobenzene analogue Ph CL 28A (2-hydroxy-5-(3,5-dimethoxycarbonyl-benzoyl)-benzene acetic acid) potently inhibited prostaglandin 15-hydroxydehydrogenase (PGDH) in the nanomolar range in-vitro and inhibited prostaglandin inactivation in rat perfused lung at similar concentrations, and is the most potent PGDH inhibitor yet available. It was synthesized because electronegative substituents in the B ring of homosalazine enhance PGDH inhibitory potency. Ph CL 28A inhibited human placental PGDH non-competitively with regard both to substrate PGF2 alpha (Ki = 18.7 +/- 0.9 nM) and the NAD+ cofactor (Ki = 57.6 +/- 2.9 nM); inhibition was greatly reduced at pH greater than or equal to 8.0. Ph CL 28A hydrolyses spontaneously in alkali (t1/2 at pH 9.0 = 45 h) to the less active dicarboxylic acid (IC50 human placental PGDH 1.6 microM versus 0.028 microM for Ph CL 28A). The new analogue is 1000 X more active than the parent compound sulphasalazine from which it derives. The IC50 values for five azobenzene analogues in rat perfused lung (Ph CL 28A = 72 nM) correlated strongly with those obtained using purified PGDH (r = 0.99), suggesting that they inhibit pulmonary prostaglandin degradation at the enzyme step rather than at the hypothetical carrier. The new compound will be a useful probe for PGDH structure and function.

Animals↗