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Biomedical subjects

E W Naylor

Publications and source records attributed to E W Naylor.

At least 19 recordsLinked to original sources
PubMed1989

Repetitive recycling of guanosine triphosphate cyclohydrolase I for synthesis of dihydroneopterin triphosphate.

A procedure for enzymatic production of dihydroneopterin triphosphate is described that allows GTP cyclohydrolase I to be reused repetitively. The reaction takes place in an ultrafiltration cell, and the product is collected in the filtrate, whereas the enzyme remains in the cell to be reused with additional substrate. This is repeated until the enzyme activity drops below a desirable level. The purity of the dihydroneopterin triphosphate is satisfactory for utilization of this compound for studies on enzymes involved in the synthesis of tetrahydrobiopterin and drosopterin. A procedure for purification of dihydroneopterin triphosphate is described that uses C18-silica and silica cartridges.

Aminohydrolases↗
PubMed1988

Sepiapterin reductase in human amniotic and skin fibroblasts, chorionic villi, and various blood fractions.

Sepiapterin reductase activity has been measured in amniotic fibroblasts by two procedures: one photometric and the other HPLC-fluorimetric. Both can be used for quantitative measurements, but the latter has considerable advantages including smaller standard deviation, much lower detection limit, and less volume of sample required. Sepiapterin reductase activity was also assayed in skin fibroblasts, chorionic villi and various blood fractions including stimulated mononuclear blood cells. Red blood cells have a low specific activity compared to unstimulated mononuclear blood cells, although the latter have a mean value with a high standard deviation. When the mononuclear blood cells were cultured for 5 days, the mean specific activity increased and the range became tighter. Enzyme stability and N-acetylserotonin inhibition were also studied.

Alcohol Oxidoreductases↗
PubMed1987

Sepiapterin reductase in cultured human cells.

Sepiapterin reductase, an enzyme involved in the synthesis of tetrahydrobiopterin (the natural cofactor for phenylalanine, tyrosine and tryptophan hydroxylases), has been assayed in cultured human amniotic fibroblasts and in cultured mononuclear blood cells. In both cases, the Michaelis constants for sepiapterin and NADPH were essentially equal; 20 microM and 6 microM respectively for stimulated mononuclear blood cells and 22 microM and 5 microM respectively for amniotic fibroblasts. The inhibition by N-acetylserotonin was also similar in both cases. The concentration that produced 50% inhibition in stimulated mononuclear blood cells and in amniotic fibroblasts was 2 microM. The results strongly suggest that the same enzyme is acting in both types of cells, at least when grown in culture.

Alcohol Oxidoreductases↗
PubMed1987

Plasma phenylethylamine and phenylalanine in chronic schizophrenic patients.

The hypothesis that phenylethylamine (PEA) is an endogenous psychotogen in schizophrenics, particularly those with the paranoid subtype, has been previously studied by measuring PEA levels in urine and cerebrospinal fluid (CSF) of schizophrenic patients. However, plasma PEA may more accurately reflect simultaneous alterations of PEA in many organ systems, as might occur in a genetic disorder of PEA metabolism. No study to date has examined phenylalanine (Phe), which is thought to be a precursor of PEA, in the same patients who had PEA measured. In this study, we measure both plasma PEA and Phe in 17 drug-free schizophrenic patients and 17 matched controls. Plasma PEA in normal controls was found to be lower by three orders of magnitude compared to normal controls from previous studies--a finding that has not previously been reported. PEA was significantly lower in those schizophrenic patients who had a Research Diagnostic Criteria diagnosis of paranoid schizophrenia. PEA did not differ between patients and controls, and the correlation between plasma Phe and PEA was not significant.

Adult↗
PubMed1987

Guanosine triphosphate cyclohydrolase I deficiency: early diagnosis by routine urine pteridine screening.

A deficiency of hepatic guanosine triphosphate cyclohydrolase I is reported in a 4-month-old infant in whom positive results on a Guthrie phenylketonuria test in the neonatal period were found. Because of the significantly elevated serum phenylalanine levels a diagnosis of classical phenylketonuria was made, and dietary therapy was started. Urinary pteridine screening for cofactor variants, however, revealed extremely low levels of both neopterin and biopterin. This suggested the possibility of guanosine triphosphate cyclohydrolase I deficiency and led to additional confirmatory assays. Repeat urine, serum, and CSF pteridine profiles, combined with tetrahydrobiopterin-loading studies and the assay of guanosine triphosphate cyclohydrolase I activity in a liver biopsy, confirmed the defect. It is significant to note that the diagnosis was made before the onset of major clinical symptoms. This case illustrates the need for routine cofactor variant screening of all infants in whom hyperphenylalaninemia is diagnosed in the neonatal period.

Aminohydrolases↗
PubMed1985

Dihydropteridine reductase in schizophrenic patients.

The activity of the enzyme dihydropteridine reductase (DHPR) has been recently found to be one of the factors controlling the rate of synthesis of dopamine, norepinephrine, and serotonin, thought to be involved in the etiology of schizophrenia. Several lines of evidence suggest that peripheral and brain DHPR enzymes may be identical. In addition, peripheral DHPR activity has been hypothesized to be important in determining the level of phenylethylamine, a putative psychotogen that is produced peripherally and crosses the blood-brain barrier. Since DHPR activity has never been investigated in schizophrenic patients, we measured the whole blood activity in 20 schizophrenic patients and 20 matched controls. There was no difference between the groups in DHPR activity.

Adult↗
PubMed1985

Simplified procedure for producing Bacillus subtilis spores for the Guthrie phenylketonuria and other microbiological screening tests.

Bacillus subtilis ATCC 6051 and ATCC 6633 spores used in bacterial inhibition screening assays for genetic metabolism defects in newborn infants were produced by using liquid synthetic replacement sporulation media. These media allowed a high degree of sporulation, as judged by direct cell counts. Sporulation took place within 23 to 27 h with these media. Also, a more rational procedure for selecting the most sensitive clones of these organisms to the various inhibitors used in the microbiological screening assays is presented.

Bacillus subtilis↗
PubMed1984

A rapid screening test for Duchenne muscular dystrophy using dried blood specimens.

A very simple fluorescent spot screening test for the detection of elevated creatine kinase activity in dried blood specimens is described. The assay uses reagents commercially available in kit form and modifies the procedure for use with whole blood spotted on filter paper. Additional amounts of diadenosine pentaphosphate had to be added to the reaction mixture to inhibit the excess adenylate kinase present in erythrocytes. The sensitivity and reliability of the test is demonstrated. This qualitative assay has the potential for use as a mass neonatal screening test for Duchenne muscular dystrophy.

Clinical Enzyme Tests↗
PubMed1982

Neonatal urine screening for metabolic disease with auxotrophic strains of Bacillus subtilis.

A simplified method for neonatal urine screening for metabolic diseases is described. This procedure involves the use of two bacterial inhibition assays which can detect uracil, lysine, and homocystine, in combination with two other assays utilizing spores of amino acid auxotrophic mutants of Bacillus subtilis which can detect several amino acids and purines. These four tests have the capability to detect several treatable inherited metabolic diseases, including three disorders of the urea cycle, using a urine specimen on filter paper. This method results in savings of cost and time over chromatographic screening procedures, since only four agar trays (56 specimens per tray) are used, which can be processed with one cycle through a semi-automated punch index machine.

Bacillus subtilis↗
PubMed1981

Urinary pyrimidine excretion in arginase deficiency.

A high-performance liquid-chromatographic method was used to separate and identify uracil, uridine, pseudouridine and orotic acid after preliminary extraction in two patients (McKusick 20780). Urinary uracil excretion was 10-35 times normal in both patients with arginase deficiency. Uridine and orotic acid, not normally detected, were excreted in large amounts and were directly influenced by protein intake. Their excretions were correlated with urinary arginine excretion. Urinary uracil levels remained consistently high and showed minimal variations with increased protein intake or urinary arginine levels. The measurement of urinary pyrimidines appears to be useful for the detection, differential diagnosis and dietary monitoring of patients with urea cycle disorders. The data presented extends this observation to include patients with arginase deficiency.

Adolescent↗
PubMed1980

Enzymatic studies of urinary isomeric chondroitin sulfates from patients with mucopolysaccharidoses. The application of high performance liquid chromatography.

The high-performance liquid chromatographic (HPLC) method for the determination of unsaturated sulfated disaccharides is a comprehensive and reliable method which expedites ensymatic studies of isomeric chondroitin sulfates. Responses for these unsaturated disaccharides derived from urinary chondroitin sulfates were linear from 100 ng to 10 micrograms injected and good quantitation was obtained for 25 microliters or less of samples placed on the column. This method which is more sensitive and accurate than methods now being used has considerable potential for the chemical diagnosis of patients with mucopolysaccharidoses and for the clarification of glycosaminoglycan structure. The isomeric chondroitin sulfates in urines from patients with mucopolysaccharidoses were studied by enzyme digestion with chondroitinases followed by HPLC determination of the sulfated unsaturated disaccharides produced. Evaluation by HPLC of the unsaturated 4-sulfated disaccharide produced by digestion of the urinary GAG with chondroitinases ABC and AC revealed rapidly and quantitatively the large amounts of dermatan sulfate present in Hurler, Hunter, and Maroteaux-Lamy urines. Chondroitin 4-sulfate predominated in Sanfilippo urinary isomeric chondroitin sulfates whereas chondroitin 6-sulfate and chondroitin 4-sulfate were shown to be present in nearly equal amounts in Morquio urine. An oversulfated chondroitin sulfate was detected in small amounts in some of these urines. This was demonstrated by the detection of an unsaturated disulfated disaccharide after digestion with chondroitinase ABC but not with chondroitinase AC.

Chondroitin↗
PubMed1979

Measurement of urinary pyrimidine bases and nucleosides by high-performance liquid chromatography.

A rapid procedure for the isolation, separation, identification and measurement of urinary pyrimidine bases and nucleosides by high-performance liquid chromatography (HPLC) is presented. The initial isolation of these compounds from urine was accomplished with small disposable ion-exchange columns. HPLC was performed on a silica gel column with a mobile phase composed of methylene chloride, methanol and 1 M aqueous ammonium formate buffer. Peaks were recorded at both 254 nm and 280 nm and the response ratio was used in combination with the elution volume for compound identification. The minimum detectable amount (signal-to-noise ratio = 2) ranged from 0.2 ng for uracil to 2.2 ng for cytidine. Linearity and recovery for thymine, uracil, uridine, pseudouridine, orotic acid and orotidine added to urine was demonstrated over almost a 10(3) concentration range. The potential application of this method for the study of inborn errors in the urea cycle is discussed.

Chromatography, High Pressure Liquid↗
PubMed1979

Desmoid tumors and mesenteric fibromatosis in Gardner's syndrome: report of kindred 109.

Kindred 109, from which Gardner's syndrome was first described, now has 224 members, 28 of whom have inherited the syndrome. Among the group of 28, desmoid tumors or mesenteric fibromatosis or both have developed in eight (29%). In four patients, the fibrous dysplasia appeared to originate in postsurgical abdominal incisional scars; in two of these cases, the mesenteric involvement resulted in death. In one patient, the process was present in the mesentery at the original operation. In three patients, the fibrous dysplastic lesions were extraincisional, with no known trauma associated with their occurrence.

Abdominal Muscles↗
PubMed1979

Early detection of adenomatous polyposis coli in Gardner's syndrome.

Gardner's syndrome, an autosomal dominant disorder, consists of multiple polyposis of the colon associated with various soft- and hard-tissue tumors. The appearance of adenomatous hyperplasia and polyposis in at-risk patients before adolescence has not been full appreciated. Four preadolescent children from a kindred with Gardner's syndrome were examined by use of colonoscopy and mucosal biopsy. In three children (18 months, 6 years, and 9 years old) adenomatous hyperplasia or polyposis was found. The colon of the fourth child (3 years old) was normal. The three affected children were asymptomatic. The youngest had a barium enema and results were normal. The oldest child had polyps. Biopsies revealed focal atypical hyperplasia of the glands with pseudostratification of the epithelial cells, frequent mitotic figures, and the absence of goblet cells. More severe manifestations were noted in the splenic flexure than in the sigmoid flexure or rectum. The youngest patient showed early adenomatous hyperplasia characterized by a marked reduction of the goblet cells, especially in the surface epithelium. Colonoscopy and mucosal biopsies are mandatory in at-risk children. By deferring colonic examination until adolescence, a patient is placed at risk for malignant degeneration of the adenomatous tumor.

Adenoma↗