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Biomedical subjects

H L Sharp

Publications and source records attributed to H L Sharp.

At least 73 records · Page 4Linked to original sources
PubMed1976

Immunodeficiency, xanthomas and obstructive liver disease.

Chronic obstructive liver disease and secondary hyperlipidemia developed in an immunodeficient boy. Sequential addition of cholestyramine and phenobarbital to his medical regimen, following an initial response to bile drainage, resulted in the disappearance of xanthomas and pruritus, and the restoration of normal serum concentrations of lipids and bile acids. This improvement may result from shifting the bile acid pool from the peripheral blood compartment to the enterohepatic circulation.

Bile Acids and Salts↗
PubMed1976

Aspartylglucosaminuria: unique biochemical and ultrastructural characteristics.

The observation of vacuolated lymphocytes in a coarsely featured two year old female with hepatosplenomegaly, mitral insufficiency, and mild psychomotor retardation led to the first diagnosed case of aspartylglucosaminuria in the United States. Although physical characteristics and bone roentgenograms were consistent with a mucopolysaccharide disorder, analysis of the urine showed no mucopolysaccharide elevation. The chromatographic, enzymatic, and ultrastructural studies confirming the diagnosis are presented.

Amidohydrolases↗
PubMed1976

Cardiac valvular anomalies in Fabry disease. Clinical, morphologic, and biochemical studies.

The cardiovascular abnormalities were investigated in two unrelated hemizygous males with Fabry disease who had clinical mitral insufficiency. Postmortem examination of their hearts revelaed anatomic, ultrastructural and biochemical abnormalities resulting from defective activity of the lysosomal enzyme, alpha-galactosidase A. The ultrastructural and biochemical studies demonstrated the marked accumulation of the major glycosphingolipd substrate, trihexosyl ceramide, in the lyosomes of all the cardiac tissues examined; the greatest concentrations were found in the mitral valve and elft ventricular myocardium. Intriguingly, digalactosyl ceramide, a glycosphingolipid substrate not detectable in normal lung, vessel or cardiac tissues, was found increased only in the lung and right heart tissues. Morphologic and chemical examination of cardiac and systemic vessels demonstrated accumulation of trihexosyl ceramide in lysosomes of the vascular endothelium. These studies demonstrate that the progressive accumulation of trihexosyl ceramide in the lysosomes of the cardiac structures and vascular system leads to the multiple cardiovascular manfiestation of Fabry disease.

Ceramides↗
PubMed1976

The glycoprotein-degrading potential of peripheral leukocytes in cystic fibrosis.

In this study, the potential problems and discrepancies in cill culture techniques were avoided by isolating leukocytes from the peripheral blood of patients with cystic fibrosis and healthy human volunteers and preparing homogenates to determine the specific activities of 5 lysosomal enzymes involved in the degradation of glycoproteins. Four lysosomal hydrolases involved in the breakdown of the carbohydrate side chain were assayed using artificial substrates. The fifth enzyme, aspartylglucosamine amido hydrolase, which cleaves the linkage between this side chain and the peptide backbone, was assayed with natural substrate. No differences in enzyme activities between the 2 leukocyte sources were observed. Because no enzyme activities were deficient and no compensatory increases were noted, we concluded that the thick, glycoprotein-rich, exocrine secretions in cystic fibrosis cannot be attributed to a defect in their catabolism.

Acetylglucosaminidase↗
PubMed1976

Mannosidosis: clinical, morphologic, immunologic, and biochemical studies.

The primary metabolic defect in mannosidosis is the deficiency of the acidic alpha-mannosidase A and B activites which results in the lysosomal accumulation of mannose-rich substrates. Out studies demonstrate that the enzymatic diagnosis of suspect homozygotes can be made reliably using plasma, isolated leukocytes, or cultured skin fibroblasts assayed carefully at the appropriate acidic pH. Immunologic studies of a mannosidosis homozygote revealed significant abnormalities of neutrophil function; these included a depressed chemotactic responsiveness and impaired phagocytosis of bacteria. Lymphocyte transformation studies showed a 20% of normal response to purified phytohemagglutinin and a 25% of normal response to concanavalin A. Three major components of alpha-mannosidase activity in normal human liver were resolved by ion exchange chromatography on DEAE-cellulose and electrophoresis on cellulose acetate gels. Electrophoresis of the liver extract from homozygote I with mannosidosis revealed only one band of activity which coelectrophoresed with the alpha-mannosidase C isozyme partially purified from normal liver. However, ion exchange chromatography revealed the presence of residual hepatic acidic activities; the residual A isozyme was eluted in a position corresponding to that of normal alpha-mannosidase A whereas the residual B activity was eluted at a slightly more electronegative position than that of normal B isozyme. The apparent Km values for alpha-mannosidase activity as determined from Linweaver-burk plots were 1.1 mM for normal liver and 0.9 mM for normal leukocytes. In contrast, the residual activity in these sources from homozygote 1 could not be saturated within the solubility range of the substrate; the apparent Km value was estimated at 15.4 mM in liver extracts. Zinc significantly lowered the apparent Km value of the acidic activity in normal liver (from 1.2 to 0.24 mM), whereas this metallic ion had little effect on the values for mannosidosis hepatic activity (from 15.4 to 12.3 mM). Unlike zinc, cobalt had its major effect on the acidic activity in the mannosidosis liver extract, lowering the apparent Km from 15.4 to 3.9 mM, whereas the apparent Km for the normal activity was increased from 1.2 to 1.9 mM. The residual acidic activities were markedly stimulated by zinc in both leukocytes (approximately 300%) and plasma ( approximately 400%) from the homozygotes and to a lesser extent in those sources from normal individuals. In contrast, cobalt enhanced the residual acidic activities in leukocytes (approximately 500%) and plasma (approximately 200%) from the homozygotes while inhibiting these acidic activities (78.9% and 47.7%, respectively) in normal individuals.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1976

Clinical observations on the biliary system in cystic fibrosis.

The biliary tree of 66 patients with cystic fibrosis was examined by conventional roentgenographic methods. Forty-five per cent of the oral cholecystograms were judged abnormal by our criteria. A study was considered abnormal if there was no visualization or if there was visualization of a microgallbladder or structural abnormality including marginal irregularities, septate gallbladder or cholelithiasis. Intravenous cholangiography was used to further study the 22 patients who did not visualize on the oral study. Again, anatomic abnormalities were prevalent but six patients in this group had normal appearing gallbladders. Abdominal pain, a frequent symptom in cystic fibrosis, was not associated with roentgenographic abnormality. No correlation was seen between the external biliary tree abnormalities and multifocal biliary cirrhosis which was present in 40% of these patients. Further, no correlation was seen between serum gamma glutamyl transpeptidase levels and either of these lesions.

Adolescent↗
PubMed1976

The metabolism of 3alpha, 7alpha, 12alpha-trihydroxy-5beta-cholestan-26-oic acid into cholic: an enzyme assay using homogenates of human liver.

An enzyme assay was developed to measure the conversion of the bile acid precursor, 3alpha, 7alpha, 12alpha-trihydroxy-5beta-cholestan-26-oic acid (THCA), into cholic acid using homogenates of human liver biopsies. The average rate of metabolism of THCA into cholic acid was found to be 3.9 +/- 0.5 (+/- 1 SD) pmoles of cholic acid formed/mg liver/minute in twelve normal liver biopsies. This assay system can be used to determine if the syndrome of neonatal cholestasis associated with a metabolic block in the conversion of THCA into cholic acid is transmitted as a genetic trait.

Adolescent↗
PubMed1976

The current status of alpha-1-antityrpsin, a protease inhibitor, in gastrointestinal disease.

Extremely deficient levels of alpha-1-antitrypsin (ALPHA1AT) predispose such deficient individuals to the development of emphysema and cirrhosis. Protease inhibitor (Pi) typing has clarified that the inherited deficiency is codominant. A glycoprotein with antigenic characteristics of alpha1AT is found in the endoplasmic reticulum of the hepatocytes of individuals with PiZ phenotype. No therapy is available except liver transplantation. Although biochemical advances in defining the nature of alpha1AT deficiency are progressing, the pathogenesis of the liver disease remains an enigma.

Adult↗
PubMed1975

Aspartylglucosaminuria: psychomotor retardation masquerading as a mucopolysaccharidosis.

A 5-year-old girl with coarse facies, visceromegaly, and vacuolated lymphocytes is presented as the first case of aspartylglucosaminuria diagnosed in this country. This metabolic defect in glycoprotein catabolism can be clinically confused with other storage diseases such as the mucopolysaccharidoses and mucolipidoses. It is not diagnosed by routine laboratory screening methods. Special studies are required to confirm the diagnosis, but a thin-layer chromatography method for screening urine is presented for use when the diagnosis is suspected. The developmental potential in this inborn error of metabolism is documented.

Amidohydrolases↗
PubMed1975

Genetic analysis of patients with chronic active hepatitis.

21 patients with chronic active hapatitis (CAH) and their families were HL-A typed. HL-A8 was significantly increased in frequency. An apparent increased frequency of HL-A1 was shown to be secondary to the increased HL-A8 due to linkage disequilibrium. Genotype analysis revealed a striking increased frequency of homozygosity for HL-A8, 6 of 21 patients (28.5%) vs. 2.8% of controls. Two patients and one normal who were homozygous for both HL-A1 and HL-A8 were found to be homozygous for a mixed lymphocyte culture (MLC) determinant 8a. Homozygous 8a cells were used as test-stimulating cells in one-way MLC reactions to determine the frequency of the expression of the 8a determinant in 17 patients and 49 controls selected for HL-A type. 8a was found to be associated with 50% of HL-A8 haplotypes and was frequent in the patient and control populations of the same HL-A types. These data suggest that susceptibility to CAH is determined by homozygosity for a gene that is in linkage disequilibrium with HL-A8 and more closely associated with the HL-A second locus then with the locus for the major MLC determinant.

Adolescent↗
PubMed1975

The metabolism of 3alpha, 7alpha, 12alpha-trihydorxy-5beta-cholestan-26-oic acid in two siblings with cholestasis due to intrahepatic bile duct anomalies. An apparent inborn error of cholic acid synthesis.

Studies were carried out in a family in which two children with cholestasis due to intrahepatic bile duct anomalies were shown to have increased amounts of the cholic acid precursor, 3alpha, 7alpha, 12alpha-trihydorxy-5beta-cholestan-26-oic acid (THCA). The metabolism of THCA was studied in one of these patients after an intravenous injection of (3H)THCA, and the cause of the increased amounts of THCA in this condition was found to be due to a metabolic defect in the conversion of this compound into cholic acid. A small amount of (3H)cholic acid was also identified after (3H)THCA administration, confirming that this metabolic defect was incomplete. Varanic acid (3alpha, 7alpha, 12alpha, 24xi-tetrahydorxy-5beta-cholestan-26-oic acid), a metabolite of THCA, could not be identified in either of these patients. By assuming that this compound would be conjugated and excreted if the metabolic block occurred after the formation of varanic acid, the defect in these patients appears to be due to a deficiency of a 24-hydroxylating enzyme system required to convert THCA into varanic acid. This condition appears to be transmitted in an autosomal recessive fashion, because the two affected patients were of opposite sex, and neither a normal sibling nor the two parents have increased amount of THCA in their bile.

Adult↗