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Biomedical subjects

P Sharp

Publications and source records attributed to P Sharp.

At least 73 records · Page 4Linked to original sources
PubMed1989

The effect of a preterm birth prevention program in 17 rural and three urban counties in northwest North Carolina.

The results of a program of low birthweight prevention in 17 rural (20,727 births) and three urban counties (15,561 births) for calendar years 1985 and 1986 are described. Records for women in the program were matched with birth certificate data by computer. Rural and urban women in and out of the program were compared by race on the following risk factors: age less than 18 years, unmarried, education less than 12 years, Medicaid recipient, not WIC recipient, inadequate prenatal care, and previous fetal or live born death. Adjusting for these risk factors, logistic regression was used to estimate program effects on low birthweight (LBW), very low birthweight (VLBW), and preterm low birthweight (PLBW) among rural women. There was a statistically significant difference (p less than or equal to 0.01) favoring women in the program for very low birthweight and preterm low birthweight in white women, and low birthweight and preterm low birthweight in nonwhite women. The differences in rural areas exceed those in urban areas for all but one mean, very low birthweight births among white women.

Adolescent↗
PubMed1989

Plasma polyenoic very-long-chain fatty acids in peroxisomal disease: biochemical discrimination of Zellweger's syndrome from other phenotypes.

The plasma of patients with inherited defects in peroxisomal biogenesis (ie, Zellweger's syndrome, infantile Refsum's disease, and neonatal adrenoleukodystrophy) shows evidence of a disturbance in the metabolism of saturated and monoenoic fatty acids with carbon chain lengths greater than 22 (VLCFA). Zellweger's syndrome plasma alone contains, in addition, increased amounts of a number of n-6 polyenoic VLCFA including 24:5, 26:5, 28:5, 30:5, and 30:6 fatty acids. These fatty acids facilitate the biochemical discrimination of Zellweger's syndrome from other related phenotypes.

Adrenoleukodystrophy↗
PubMed1988

The occurrence of polyenoic very long chain fatty acids with greater than 32 carbon atoms in molecular species of phosphatidylcholine in normal and peroxisome-deficient (Zellweger's syndrome) brain.

The n-6 tetra- and pentaenoic fatty acids with carbon chain lengths greater than 32 found in normal brain are located predominantly in a separable species of phosphatidylcholine. A similar phospholipid is found in increased amounts in the brain of peroxisome-deficient (Zellweger's syndrome) patients, but the fatty acid composition differs in that penta- and hexaenoic derivatives predominate. Our data strongly suggest that the polyenoic very long chain fatty acids are confined to the sn-1 position of the glycerol moiety, while the sn-2 position is enriched in saturated, monounsaturated and polyunsaturated fatty acids with less than 24 carbon atoms. It is postulated that these unusual molecular species of phosphatidylcholine may play some, as yet undefined, role in brain physiology.

Brain Chemistry↗
PubMed1988

Treatment of infantile phytanic acid storage disease: clinical, biochemical and ultrastructural findings in two children treated for 2 years.

Two patients with infantile phytanic acid storage disease (infantile Refsum disease), one of whom showed the presence of morphologically normal peroxisomes in a liver biopsy, were treated with a low phytanic acid diet for more than 2 years and the effects of treatment on certain clinical, biochemical and ultrastructural parameters were examined. Both patients showed evidence of either an improvement or stabilisation in their clinical condition. Plasma phytanic acid levels decreased to near normal values in approximately 6 weeks after the introduction of the diet; plasma pipecolic acid also declined markedly but the decrease was not so rapid and its level remained abnormal. C26:C22 fatty acid ratios decreased very slowly and even after 2 years the values remained grossly abnormal. Despite the marked reduction of phytanic acid in the liver, there was an increase in the C26:C22 fatty acid ratios and this appeared to be paralleled by an increase in inclusion bodies. Our data suggest that some patients with the infantile form of Refsum disease may show some clinical benefit from dietary management and this is reflected biochemically by decreases in the plasma levels of phytanic acid and pipecolic acid.

Eicosanoic Acids↗
PubMed1988

Accumulation of pristanic acid (2, 6, 10, 14 tetramethylpentadecanoic acid) in the plasma of patients with generalised peroxisomal dysfunction.

The plasma of some patients with biochemical evidence of a generalised peroxisomal dysfunction (GPD) show greatly increased levels of phytanic acid as well as its alpha-oxidation product, pristanic acid (2, 6, 10, 14-tetramethylpentadecanoic acid). Increased amounts of 14- and 16- carbon branched chain fatty acids are also found in some of these patients. As pristanic acid is present in normal or near-normal amounts in classical Refsum disease and rhizomelic chondrodysplasia, two disorders characterised by deficiencies in phytanic acid oxidation, we speculate that its accumulation is not secondary to a defect in the alpha-oxidation of phytanic acid, but is indicative of a block in the peroxisomal beta-oxidation of pristanic acid. The finding of phytanic acid, as well as a number of its metabolites in patients with inherited defects in peroxisomal biogenesis indicates that a number of the steps in phytanic acid degradation may be confined to peroxisomes.

Adrenoleukodystrophy↗
PubMed1988

Identification of women at high risk for preterm-low-birthweight births.

Preterm-low-birthweight births comprise a subset of extremely high-risk low-birthweight infants. While numerous studies have evaluated risk factors to predict an individual's chance of a high-risk pregnancy, few have identified risk factors specifically related to preterm-low-birthweight births. Risk factors for preterm-low-birthweight births were analyzed in a sample of 11,623 women from northwest North Carolina enrolled in a low-birth-weight prevention program. Significant risk factors for preterm-low-birthweight births in this population were identified, and weights were assigned to each factor. Application of the weighting system to each patient's specific risk factors identifies women at high risk for a preterm-low-birthweight birth and assists in the determination of appropriate intervention. These data make use of all current information in the low-birthweight births prevention project. Prospective assessment of the scoring system as the project continues should improve the ability to identify and intervene with women at highest risk for a preterm-low-birthweight birth.

Adult↗
PubMed1988

Rhizomelic chondrodysplasia punctata: clinical, pathologic, and biochemical findings in two patients.

The clinical, pathologic, and biochemical features of rhizomelic chondrodysplasia punctata are described in two patients. Although both patients had clinical and radiologic similarities, one patient survived for only 13 days and the other is still alive at 8 years. The most prominent pathologic feature was the marked degenerative change in the chondrocytes from resting cartilage. Fibroblast alkyldihydroxyacetone phosphate synthase activity was markedly reduced in both patients (approximately 10% of control mean); in contrast, dihydroxyacetone phosphate acyltransferase activity was only moderately reduced (50% of control mean). Alkyl and alk-l-enyl ether (plasmalogens) levels were very low in brain and liver. The accumulation of phytanic acid observed in plasma or liver was paralleled by a reduced ability of the patients' fibroblasts to oxidize phytanic acid. Our data indicate that the genetic defect in rhizomelic chondrodysplasia punctata results in abnormalities in two apparently unrelated pathways (i.e., phytanic acid oxidation and ether lipid biosynthesis.

Brain↗
PubMed1988

A comparison of women in and out of a prematurity prevention project in a North Carolina perinatal care region.

We assessed a prematurity prevention project in a North Carolina region with 21,000 annual births in terms of its impact on low birthweight. Project records were matched to birth certificates in order to compare characteristics of women in and out of the program who received prenatal care from private providers. A logistic regression analysis, in which the effects of race, marital status, age, and other risk factors for low birthweight were statistically controlled, showed that women not in the project were 1.32 times (95% Confidence Interval 1.14, 1.54) as likely as project participants to have a birth under 2500 grams. The relative risk for non-participants for a birth under 1500 grams was 1.87 (95% CI 1.25, 2.80). Strengths and limitations of the study are discussed. The results are consistent with previous work examining the etiologies of low birthweight in private versus public patients.

Adolescent↗
PubMed1987

Structure and lipid distribution of polyenoic very-long-chain fatty acids in the brain of peroxisome-deficient patients (Zellweger syndrome).

The polyenoic fatty acids with carbon chain lengths from 26 to 38 (very-long-chain fatty acids, VLCFA) previously detected in abnormal amounts in Zellweger syndrome brain have been shown to be n-6 derivatives and therefore probably derived by chain elongation of shorter-chain n-6 fatty acids such as linoleic acid and arachidonic acid. Polyenoic VLCFA are also present in Zellweger syndrome liver, but this tissue differs significantly from brain in that the saturated and mono-unsaturated derivatives are the major VLCFA. Zellweger syndrome brain polyenoic VLCFA are present in the neutral lipids predominantly in cholesterol esters, with smaller amounts in the non-esterified fatty acid and triacylglycerol fractions. These fatty acids are barely detectable in any of the major phospholipids, but are present in significant amounts in an unidentified minor phospholipid. The polyenoic VLCFA composition of this lipid differs markedly from that observed for all other lipids, as it contains high proportions of pentaenoic and hexaenoic fatty acids with 34, 36 and 38 carbon atoms. A polar lipid with the chromatographic properties in normal brain contains similar fatty acids. It is postulated that the polyenoic VLCFA may play an important role in normal brain and accumulate in Zellweger syndrome brain because of a deficiency in the peroxisomal beta-oxidation pathway, although a possible peroxisomal role in the control of carbon-chain elongation cannot be discounted.

Brain Chemistry↗
PubMed1986

The occurrence of polyenoic fatty acids with greater than 22 carbon atoms in mammalian spermatozoa.

Fatty acids with carbon chain lengths greater than 22 (VLCFA) have been detected in boar, ram, bull and human spermatozoa. Saturated and mono-unsaturated fatty acids were present in all spermatozoa but, except for human spermatozoa, polyenoic fatty acids were quantitatively the most important components. Marked differences in polyenoic fatty acid composition were observed. Whereas human spermatozoa contain predominantly di-, tri- and tetraenoic fatty acids with up to 32 carbon atoms, boar, ram and bull spermatozoa also contain pentaenoic and/or hexaenoic acids with up to 34 carbon atoms. Human and boar spermatozoa differ markedly from those of the ram and bull in that only n-6 series acids are present.

Animals↗
PubMed1986

Detection of a homologous series of C26-C38 polyenoic fatty acids in the brain of patients without peroxisomes (Zellweger's syndrome).

The brains of patients with inherited abnormalities in peroxisomal structure and function contain greatly increased proportions of a homologous series of unique polyenoic fatty acids with carbon chain lengths ranging from 26 to 38. Based on evidence by chemical ionization and electron impact mass spectrometry before and after catalytic hydrogenation, and argentation t.l.c., these lipids have been tentatively identified as 26:5, 28:5, 30:5, 30:6, 30:7, 32:5, 32:6, 32:7, 34:5 and 34:6 fatty acids. A further two fatty acids eluting at very high temperatures from gas chromatography columns have been tentatively identified on the basis of their chemical ionization mass spectra as 36:6 and 38:6 fatty acids.

Brain↗
PubMed1986

Prenatal diagnosis of Zellweger syndrome and related disorders: impaired degradation of phytanic acid.

Normal amniocytes and chorionic villous cells in culture are able to produce 14CO2 from exogenous [1-14C] phytanic acid. In contrast, cells from four fetuses at risk for the cerebro-hepato-renal (Zellweger) syndrome and related disorders showed a greatly reduced activity, indicating a block in oxidation of the fatty acid. Our data confirm that phytanic acid oxidase activity measurement can be used for the prenatal assessment of this group of disorders.

Adult↗
PubMed1986

Variable decelerations during nonstress tests are not a sign of fetal compromise.

An examination of 908 fetal heart rate tests of 418 consecutive patients revealed brief variable decelerations in more than 50.7% of the patients. Although an association existed with nuchal cord location found at delivery, no association existed between these variable decelerations and fetal heart rate decelerations during labor, low Apgar scores at birth, or birth weight. We find no evidence to suggest that these brief variable decelerations are a sign of fetal compromise or an indication for obstetric intervention.

Apgar Score↗
PubMed1986

Regional cerebral glucose transport in insulin-dependent diabetic patients studied using [11C]3-O-methyl-D-glucose and positron emission tomography.

Regional cerebral [11C]3-O-methyl-D-glucose ([11C]MeG) uptake kinetics have been measured in five insulin-dependent diabetic patients and four normal controls using positron emission tomography (PET). Concomitant measurement of regional cerebral blood volume and CBF enabled corrections for the presence of intravascular [11C]MeG signal in cerebral regions of interest to be carried out, and regional cerebral [11C]MeG unidirectional extraction fractions to be computed. Four of the five diabetic subjects were studied with their fasting plasma glucose level clamped at a normoglycaemic level (4 mM), and four were studied at hyperglycaemic plasma glucose levels (mean 13 mM). The four diabetic subjects whose fasting plasma glucose levels were clamped at a normoglycaemic level of 4 mM had mean fasting whole-brain, cortical, and white matter [11C]MeG extraction fractions of 15, 15, and 16%, respectively, values similar to those found for the four normal controls (whole brain, 14%; cortex, 13%; white matter, 17%). Mean regional cerebral [11C]MeG extraction fractions were significantly reduced in diabetic subjects during hyperglycaemia whether their plasma insulin levels were undetectable or whether they were raised by continuous intravenous insulin infusion. Such a reduction in [11C]MeG extraction under hyperglycaemic conditions can be explained entirely in terms of increased competition between [11C]MeG and D-glucose for the passive facilitated transport carrier system for hexoses across the blood-brain barrier (BBB). It is concluded that the number and affinity of D-glucose carriers present in the BBB are within normal limits in treated insulin-dependent diabetic subjects. In addition, insulin appears to have no effect on the transport of D-glucose across the BBB.

3-O-Methylglucose↗
PubMed1986

Accumulation and defective beta-oxidation of very long chain fatty acids in Zellweger's syndrome, adrenoleukodystrophy and Refsum's disease variants.

The accumulation of very long chain fatty acids in plasma and skin fibroblasts was measured in at least four separate inherited disease states. Both the magnitude and the nature of the fatty acid changes reflected the clinical status of individual patients. In Zellweger's syndrome, and to a lesser extent in infantile Refsum's disease, there was an increase in 24:0, 26:0, 26:1, and a number of even longer chain fatty acids, while in the X-linked form of adrenoleukodystrophy these changes were less pronounced. Zellweger fibroblasts in culture took up lignoceric, phytanic and stearic acids and incorporated them into a variety of lipids in a manner comparable to control fibroblasts. However, these cells were unable to convert phytanic or lignoceric acid to CO2. Infantile Refsum's and X-linked adrenoleukodystrophy fibroblasts showed normal conversion of these acids to CO2. Normal fibroblast homogenates produced radioactive acetate from [1-14C] stearic and [1-14C] lignoceric acids indicating that both substrates were beta-oxidised under these conditions. Homogenates of fibroblasts from all patients patients with biochemical evidence of accumulation of very long chain fatty acids showed normal or near-normal stearic acid beta-oxidation, but were deficient in lignoceric acid beta-oxidation. Residual lignoceric acid beta-oxidation activity varied from approximately 15% in Zellweger syndrome up to 50% in X-linked adrenoleukodystrophy. It is postulated that the accumulation of very long chain fatty acids results from defects in peroxisomal beta-oxidation. In Zellweger's syndrome, and possibly in infantile Refsum's disease, it is probable that this defect is secondary to a primary abnormality affecting the structure and/or function of peroxisomes, while the primary defect in X-linked adrenoleukodystrophy may be confined to a pathway specific for the oxidation of very long chain fatty acids.

Adrenoleukodystrophy↗
PubMed1986

Modulation of carcinogenesis by dietary factors.

The purpose of this report is to present recent data on two modulating factors of carcinogenesis that are found in Western-type diets: a beef-derived mutagenesis modulator that has been shown to inhibit the initiation of epidermal carcinogenesis in mice, and the possible role of net energy rather than dietary fat per se in the enhancement of rat mammary carcinogenesis.

Animals↗
PubMed1986

Application of iodine-123-labeled isopropylamphetamine imaging to the study of dementia.

Forty-seven patients diagnosed as clinically demented were imaged with 123I isopropylamphetamine (IMP). All of these patients also had a nuclear magnetic resonance (NMR) study. In those patients diagnosed as having senile dementia of the Alzheimer type a bilateral reduction in IMP uptake in the temporo-parieto-occipital region was always seen. The NMR appearances were normal in 64% of these sites. The IMP images of patients with multi-infarct dementia varied from normal to marked focal deficits. There was, however, a much closer agreement between the abnormalities seen on the IMP and NMR images. In alcoholic dementia no focal areas of reduced IMP uptake were seen, although the uptake was generally irregular. In both Korsakoff's psychosis and Huntington's chorea the IMP uptake pattern and the NMR study were normal.

Aged↗