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Biomedical subjects

R Mandell

Publications and source records attributed to R Mandell.

33 records · Page 2Linked to original sources
PubMed1980

Tear pumping and edema with soft contact lenses.

The effect of the contact lens--cornea bearing relationship on tear pumping and corneal swelling (edema) which accompanies hydrogel lens wear was determined by monitoring corneal thickness and tear replenishment rates when the base curve (back surface curvature) was varied from 7.8 to 9.0 mm. The lens movement is dependent on the bearing relationship; however, the degree of corneal swelling and the replenishment rate of tears under the lens are independent of the bearing relationship. These results indicate that the corneal edema which accompanies gel lens wear cannot be reduced by altering the lens-cornea bearing relationship.

Adult↗
PubMed1979

Medium for selective isolation of Fusobacterium nucleatum from human periodontal pockets.

A selective medium, CVE agar, was developed for the isolation of Fusobacterium nucleatum from subgingival plaque of periodontally diseased patients. The medium contained 1.0% Trypticase (BBL Microbiology Systems), 0.5% yeast extract, 0.5% NaCl, 0.2% glucose, 0.02% L-tryptophan, 1.5% agar, and 5% defibrinated whole sheep blood. Erythromycin and crystal violet were added as the selective inhibitory agents at concentrations of 4 and 5 micrograms/ml, respectively. The medium permitted almost total recovery of F. nucleatum when compared with a nonselective medium and suppressed the recovery of most remaining species by nonselective medium and suppressed the recovery of most remaining species by 6 to 8 orders of magnitude. Microorganisms suppressed to a lesser degree included Selenomonas sputigena, Actinobacillus actinomycetemcomitans, Eikenella corrodens, and some strains of Peptostreptococcus. The distinct colonial morphology of F. nucleatum on CVE agar made differentiation relatively easy when contaminants were present. With this medium, F. nucleatum was enumerated from 278 subgingival plaque samples and accounted for less than 1.0 to greater than 25% of the cultivatable microbiota.

Adolescent↗
PubMed1979

Oxygen-transmitting hard contact lenses.

Nine PMMA contact lens wearers with persistent corneal edema were refitted with CAB contact lenses. All of the patients showed less corneal swelling with CAB lenses than with PMMA lenses.

Acetates↗
PubMed1978

Ornithine ketoacid transaminase deficiency in gyrate atrophy of the choroid and retina.

Gyrate atrophy of the choroid and retina is a chorioretinal degeneration associated with hyperornithinemia with an autosomal recessive mode of inheritance. Cultured skin fibroblasts from five affected patients showed a virtual absence of ornithine ketoacid transaminase (OKT) (L-ornithine:2-oxoacid aminotransferase E.C.2.6.1.13) activity. Fibroblasts from four carrier parents showed a 42%-65% reduction in OKT activity. Increasing the concentration of pyridoxal phosphate (vitamin B6 in the assay media resulted in partial restoration of OKT activity in fibroblasts from one out of five patients studied. We conclude that OKT deficiency is closely associated with the genetic defect in gyrate atrophy of the choroid and retina and that genetic heterogeneity exists in this disease.

Adolescent↗
PubMed1977

Sulfite oxidase deficiency. Biochemical and clinical investigations of a hereditary metabolic disorder in sulfur metabolism.

Study of a 4 1/2-year-old boy with the unusual combination of acute infantile hemiplegia, ectopia lentis and the absence of homocystinuria showed large amounts of abnormal sulfur-containing metabolites (sulfite, thiosulfate and S-sulfocysteine) in the urine. Sulfite and S-sulfocysteine were also present in the plasma. His inorganic sulfate excretion was only 50 per cent of total sulfur, as compared with 75 to 95 per cent by controls. Loading with L-cysteine hydrochloride and L-methionine further increased the excretion of sulfite and thiosulfate, but not inorganic sulfate excretion. Sulfite oxidase activity in skin fibroblasts average 1.07 nmol of cytochrome d reduced per milligram of protein per minute in control lines; it was not detectable (less than 5 per cent) in the patient. Activity was reduced in both parents (0.50 in the father and 0.32 in the mother)--compatible with autosomal recessive inheritance. Good biochemical responses to a low sulfur amino acid diet suggest that early treatment may benefit the patient.

Amino Acids, Sulfur↗
PubMed1976

Metabolism of [1-(14)C] and [2-(14)C] leucine in cultured skin fibroblasts from patients with isovaleric acidemia. Characterization of metabolic defects.

Leucine metabolism in cultured skin fibroblasts from patients with isovaleric acidemia was compared with that in normal fibroblasts and in cells from patients with maple syrup urine disease using [1-(14)C] and [2-(14)C] leucine as substrates. Inhibitory effects of methylenecyclopropylacetic acid on leucine metabolism in normal cells were also investigated. Production of 14CO2 from [2-(14)C] leucine was very reduced (96-99%) in both types of mutant cells. Radioactive isovaleric acid accumulated in assay media with isovaleric acidemia cells but not in those with maple syrup urine disease cells. Unexpectedly, 14CO2 production from [1-(14)C] leucine was partially depressed (80%) in isovaleric acidemia cells whereas in maple syrup urine disease cells it was strongly depressed (99%) as expected. These two mutant cells were clearly distinguished by detection of 14C-isovaleric acid accumulation after incubation with [2-(14)C] leucine. A pattern of inhibition of leucine oxidation similar to that seen in isovaleric acidemia cells was induced in normal cells by the addition of 0.7 mM methylenecyclopropylacetic acid to the assay medium. The partial inhibition of [1-(14)C] leucine oxidation seen in isovaleric acidemia cells and also in normal cells in the presence of the inhibitor appears to be, at least in part, due to an accumulation of isovalerate in the cells. Isovaleric acid (5-10) mM) inhibited [1-(14)C] leucine oxidation 32-68% when added to the assay medium with normal cells. Addition of flavin adenine dinucleoside to culture medium or assay medium or both did not restore oxidation of either leucine substrate in isovaleric acidemia cells.

2-Methyl-4-chlorophenoxyacetic Acid↗
PubMed1975

Comparison of galactose-1-phosphate uridyl transferase in fetal and adult tissues.

Galactose-1-phosphate uridyl transferase, the enzyme deficient in galactosemia, is demonstrated to be present in erythrocytes from fetuses of 12--30 weeks gestation. The specific activity and starch gel electrophoretic pattern of this enzyme in fetal erythrocytes is virtually identical to that found in erythrocytes postnatally. This enzyme was also studied in cultured fibroblasts from skin and amniotic cells and found to have similar specific activity and identical electrophoretic mobility in tissues from both sources. There does not appear to be a fetal isozyme for galactose-1-phosphate uridyl transferase in either erythrocytes or cultured fibroblasts. Thus, with fetal erythrocytes obtained by fetoscopy, it is likely that prenatal diagnosis of galactosemia can be rapidly and reliably accomplished.

Adult↗
PubMed1975

Galactose-1-phosphate uridyl transferase in fibroblasts: isozymes in normal and variant states.

Electorphoretic properties of galactose-1-phosphate uridyl transferase in cultured skin fibroblasts of normal humans and individuals with different enzyme variants have been studied. Normal fibroblast lysates showed four activity bands, each slower moving than the erythrocyte enzyme. The transferase variants revealed different mobilities analogous to those found in erythrocytes. These findings suggest that subunits of human transferase associate variously with one another in a manner specific for each tissue and that in transferase variant states, an altered subunit results in a characteristic alteration in electrophoretic mobility which is analogous for each tissue.

Electrophoresis, Starch Gel↗
PubMedDate not supplied

Free amino acids in extracts of cultured skin fibroblasts from patients with various amino acid metabolic disorders.

In the search for a simple screening test for prenatal diagnosis of amino acid metabolic disorders, we compared the free amino acid contents in the extract of cultured skin fibroblasts from normal individuals with that from patients with 10 metabolic disorders: maple-syrup urine disease; homocystinuria due to cystathionine synthase deficiency; homocystinuria due to N5, 10-methylene-tetrahydrofolate reductase deficiency; citrullinemia; argininosuccinic acidemia: propionic acidemia; hyperprolinemia Type II; non-ketotic hyperglycinemia; hydroxyprolinemia; and hyperonithinemia. An accumulation of abnormal metabolites was not found in any of the disorders except argininosuccinic aciduria. Argininosuccinic acid anhydrides were detected in cell extracts from all four patients only after the extract was boiled at acid pH for 2 1/2 h. Thus, it is concluded that the measurement of free amino acids in extracts from cultured fibroblasts is not a useful screening technique in the diagnosis of inborn errors of amino acid metabolism.

Amino Acid Metabolism, Inborn Errors↗