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Biomedical subjects

J A Phillips

Publications and source records attributed to J A Phillips.

At least 199 records · Page 11Linked to original sources
PubMed1985

Evaluation of dietary practices of college women based on expressed concern for one's dietary habits.

On the basis of expressions of concern for their dietary practices, those noting much concern were more likely to practice nutrient supplementation as a margin of safety against possible dietary deficiencies and to rate their diets as good. Although those subjects were more likely to view their body size with satisfaction than subjects in other groups, the majority in each group tended to believe that they were overweight. Diets of those expressing much concern were more likely to meet 100% of the RDAs than diets of other groups.

Adolescent↗
PubMed1984

Effect of cimetidine and ranitidine on carbamazepine and sodium valproate pharmacokinetics.

The pharmacokinetics of a single oral dose (400 mg) of carbamazepine and sodium valproate were compared in peptic ulcer patients before and after four weeks of a therapeutic course of either cimetidine (1 g/day, n = 6 subjects) or ranitidine (300 mg/day, n = 6 subjects). There was a small (up to 20%) but statistically significant decrease in oral clearance of carbamazepine after cimetidine treatment. A similar fall in sodium valproate clearance in five cimetidine-treated patients was accompanied by a significantly prolonged elimination half-life. No such trends were demonstrated during ranitidine treatment. Since both anticonvulsants are partly metabolized by hepatic mixed function oxidases, an inhibition by cimetidine at this level may be responsible for the observed impairment of clearance. Thus a potentially important clinical interaction may occur in patients taking anticonvulsants and cimetidine concurrently.

Carbamazepine↗
PubMed1984

Isolated growth hormone deficiency type 1A in a Japanese family.

A Japanese family is described in which a 7-year-old child had isolated growth hormone deficiency type 1A, as described by Illig et al. He was shown to be homozygous for a deletion of the structural gene for hGH (hGH-N gene). Initially his growth rate responded well to hGH administration, but rapidly he developed high titers of hGH antibodies, and growth ceased. At that time, a somatomedin-C generation test gave negative results, suggesting that the growth arrest was related to the inability of hGH to generate somatomedin. Both parents were heterozygous for the hGH-N gene deletion and had a low hGH response to arginine and L-dopa tolerance tests, but had normal basal somatomedin-C levels and normal somatomedin-C generation tests. This family is the fourth to be reported with IGHD type 1A caused by deletion of the hGH-N gene. This cause of growth hormone deficiency can be distinguished from other severe autosomal recessive types of hGH deficiency by the demonstration of the deletion of hGH-N gene using restriction endonuclease analysis.

Adult↗
PubMed1984

Patterns of polymorphism and linkage disequilibrium suggest independent origins of the human growth hormone gene cluster.

Six restriction fragment length polymorphisms (RFLPs) detected in the human growth hormone-human chorionic somatomammotropin (hGH-hCS) gene cluster were studied in Mediterraneans, Northern Europeans, and American Blacks; the polymorphisms showed that, on the average, one of 500 bases in this cluster is variant. Haplotypes constructed for four of these RFLPs display strong nonrandom associations. However, the strongest associations were between RFLPs that are in homologous DNAs rather than between the physically closest RFLPs. From this and other evidence we argue that duplication of an ancestral hCS gene occurred at least twice, the second event being relatively recent. In other words, duplication of the hCS-L gene to produce the hCS-A gene occurred twice, so that hCS-A genes in humans may have independent origins. Our results imply that chromosomes with absent hCS genes (leading to hCS deficiency) may represent the nonduplicated ancestral unit rather than gene deletions.

Amniotic Fluid↗
PubMed1984

Phenotypic heterogeneity in familial isolated growth hormone deficiency type I-A.

We studied an Argentinian family of Spanish ancestry in which the parents are of normal height and three of their four children have isolated GH deficiency type I-A. Restriction endonuclease analysis of DNA isolated from leukocytes was done using 32P-labeled human GH (hGH) cDNA sequences as a probe. The three siblings were homozygous, while their parents and the remaining sibling were heterozygous for a deletion of about 7.5 kilobases DNA, which included the normal hGH gene. The phenotype of the affected subjects differed in several respects. There was variation between the homozygotes in birth length and height before hGH treatment and growth responses during long term hGH treatment. Furthermore, heterozygotes in this family had normal height despite their diminished hGH responses to provocative tests.

Adolescent↗
PubMed1983

Prenatal diagnosis using DNA polymorphisms. Report on 95 pregnancies at risk for sickle-cell disease or beta-thalassemia.

DNA polymorphisms are normal inherited variations in DNA that can often be used to document the inheritance of genes that produce disease. In this report we summarize our experience with prenatal diagnosis in 95 pregnancies in which the fetus was at risk for a hemoglobinopathy; the diagnosis was performed with use of DNA polymorphisms located so near the beta-globin gene that they are inherited along with that gene. Of the 95 pregnancies, 57 involved fetuses at risk for sickle-cell anemia, 32 fetuses at risk for beta-thalassemia, and 6 fetuses at risk for other beta-chain hemoglobinopathies. Diagnosis was achieved solely by analysis of DNA polymorphisms in cells recovered by amniocentesis in 82 cases (86 per cent) and was completed by fetoscopy and fetal-blood study in an additional 6 cases (6 per cent). Prenatal diagnosis was proved correct in all 78 cases that have been available for confirmation to date. Our experience demonstrates that DNA polymorphisms can be useful for the prenatal diagnosis of genetic diseases in which the basic defect cannot be directly detected.

Amniocentesis↗
PubMed1983

Respiratory complications of achondroplasia.

Nine patients with achondroplasia who were seen over a three-year period developed significant respiratory complications. Eight had sleep-disordered breathing, including obstructive sleep apnea in five, for which two required tracheostomy. Of the seven patients with significant hypoxemia, five had clinical evidence of cor pulmonale and recurrent pulmonary infiltrates. Two patients died, one with autopsy findings of compression of the medulla at the level of the foramen magnum and one with respiratory and cardiac failure. Appropriate therapy for our patients depended on recognition of the mechanisms that led to the respiratory complications, including (1) chest deformity, (2) upper airway obstruction and sleep-disordered breathing, (3) neurologic complications, and (4) coincidental chronic pulmonary conditions such as asthma.

Achondroplasia↗
PubMed1983

Beta-globin locus is linked to the parathyroid hormone (PTH) locus and lies between the insulin and PTH loci in man.

Using a parathyroid hormone (PTH) cDNA probe we found a common Pst I polymorphic restriction site 3' to the PTH gene in all ethnic groups examined. Because the PTH, insulin, and beta-globin loci have been localized to the short arm of chromosome 11 (11p) we used DNA polymorphisms adjacent to each of these three loci to determine whether they are genetically linked and to determine their order. We found that the PTH and beta-globin loci are closely linked (estimated recombination fraction, 0.07; 95% confidence limits, 0.05-0.10; lod score, 4.63; odds favoring linkage, 42,000:1). Furthermore, our findings strongly indicate that the beta-globin gene cluster lies between the PTH and insulin loci. Therefore, the gene order on 11p is centromere-PTH-beta-globin-insulin.

Chromosomes, Human, 6-12 and X↗
PubMed1983

Etiology of growth hormone deficiency in little, Ames, and Snell dwarf mice.

There are three recessive genes (little, Snell, and Ames) which cause dwarfism and GH deficiency in mice. These genes are nonallelic, and in the case of little mice, GH deficiency is isolated, while Snell and Ames dwarfs have deficiencies of GH as well as other anterior pituitary hormones. Previous reports in which restriction endonuclease analyses were used suggested that the GH genes are grossly intact in each of these types of dwarfs. In this report, ultrastructural studies of the anterior pituitary glands of little mice showed a deficiency or absence of secretory granules within somatotropes, while Snell and Ames dwarf pituitaries lacked identifiable somatotropes. Furthermore, there were deficiencies of GH precursor RNA and mRNA in total RNA from little pituitaries, while GH transcripts appeared to be absent in total RNA from Snell or Ames dwarf pituitaries. Thus, the primary defect in little mice may be in the production of GH transcripts, while GH deficiency in Snell and Ames dwarfs is probably due to defects other than alterations of the GH genes.

Animals↗
PubMed1983

Clinical applications of restriction endonuclease analysis.

These are exciting times in human genetics. Recombinant DNA technology has enabled investigators to sequence human genes so that the structure and organization of some genes is now known. These observations led to studies of "natural mutations," such as the hemoglobinopathies and thalassemias. This information in turn provided insight so that many mutations affecting the alpha- or beta-globin genes can now be detected prenatally. It seems probable that these techniques will be applicable to many other human genetic diseases. In the future, however, the greatest impact of these advances may be through their applications to produce proteins, such as hormones and vaccines, which can be used to treat deficient patients.

Anemia, Sickle Cell↗
PubMed1982

Relative levels of methylation in human growth hormone and chorionic somatomammotropin genes in expressing and non-expressing tissues.

It has been shown that the extent of methylation of cytosine in vertebrate DNA is inversely correlated with gene expression. We studied cytosine methylation in and around the homologous human growth hormone (GH) and chorionic somatomammotropin (CS) genes to determine if these genes are undermethylated in DNA from tissues in which they are expressed (pituitary and placenta, respectively) compared to other tissues. Hpa II and Hha I (which cleave only unmethylated 5' CCGG 3' and 5' GCGC 3' respectively) and Msp I (which cleaves CCGG and CmeCGG) were used to digest DNA samples followed by gel electrophoresis, Southern transfer and hybridization with a GH cDNA probe. The extent of methylation of Hpa II and Hha I sites in the GH and CS genes was leukocyte much greater than pituitary greater than placenta = hydatidiform mole. Taken as a whole, our data support the hypothesis that undermethylation is a necessary but not sufficient condition for gene expression since placental and pituitary DNAs are less methylated than leukocyte DNA in this region. However, the correlation between gene expression and undermethylation is imperfect since (1) hydatiform mole DNA has a very similar methylation pattern compared to placental DNA even though moles make little or no CS and (2) the level of methylation of the GH gene compared to the CS gene does not vary in a tissue-specific manner.

5-Methylcytosine↗
PubMed1982

Hemoglobin H disease and multiple congenital anomalies in a child of northern European origin.

Hemoglobin H (HbH) disease was recently described in three unrelated northern European boys with mental retardation. We have studied a somewhat similar patient, in whom HbH disease was associated with multiple congenital anomalies. Restriction endonuclease analysis of DNA from this proband yielded a pattern consistent with the alpha-/-- genotype commonly associated with the HbH phenotype in Asians. His parents both carry alpha thalassemia, in contrast to the previously described families in which only one of the two parents was a carrier.

Abnormalities, Multiple↗
PubMed1982

Circadian rhythms and the effects of exogenous melatonin in the nine-banded armadillo, Dasypus novemcinctus: a mammal lacking a distinct pineal gland.

Circadian rhythms of body temperature, activity and oxygen consumption were recorded in the nine-banded armadillo, Dasypus novemcinctus, a mammal lacking a distinct pineal gland. The rhythms were entrained by light-dark cycles and appeared to be phase-coupled. Under constant illumination, the animals displayed free-running circadian rhythms with period lengths of slightly less than 24 hr. Melatonin implants caused a lengthening of the free-running period of activity and body temperature. The occurrence of a "normal" circadian rhythmicity in the armadillo indicates that the pineal organ is not necessary for the circadian organization of this animal whereas melatonin of non-pineal origin may have a role.

Animals↗
PubMed1982

Pinealectomy in ground squirrels: effect on behavioral and physiological responses to heat stress.

Richardson's ground squirrels, 1 year after pinealectomy, showed altered behavioral and physiological responses to heat stress when compared to an intact group. Pinealectomized squirrels bar-pressed more often for a cool temperature reward in a hot environment. when deprived of behavioral control of the hot environment, pinealectomized squirrels increased their oxygen consumption, had a higher body temperature, and displayed signs of greater thermal stress, including death, as compared to intact animals. When the intact group was pinealectomized and the experiments were repeated, the difference in behavioral and physiological responses to heat stress were not as great as with the 1 year pinealectomized group. A speculative explanation of the pineal gland's influence on central and peripheral control of evaporative water loss and peripheral blood circulation are offered. The pineal gland may exert a subtle influence on heat transfer mechanisms and adaptations to thermal stress.

Animals↗