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J C Tutor

Publications and source records attributed to J C Tutor.

At least 37 records · Page 2Linked to original sources
PubMed1994

Activation energy of serum 5'-nucleotidase as a marker for enzyme heterogeneity.

Using adenosine 5'-monophosphate (Arkesteijn; J. Clin. Chem. Clin. Biochem. 14 (1976) 155) and inosine 5'-monophosphate (Bertrand & Buret; Clin. Chim. Acta 119 (1982) 275) as substrates for the determination of serum 5'-nucleotidase, linear Arrhenius plots were obtained between 25 degrees C and 37 degrees C. With the latter method, in patients with hepatobiliary disease, activation energy is higher than in healthy subjects (67.8 +/- 0.8 kJ.mol-1 vs. 59.2 +/- 1.6 kJ.mol-1, p < 0.001). Neuraminidase treatment resulted in a significant reduction in the activation energy of serum 5'-nucleotidase from patients (63.6 +/- 0.6 kJ.mol-1, p < 0.001). Although the activation energy seen is also influenced by conditions other than sialic acid content, the results obtained are in accordance with the hypothesis that in liver disease serum 5'-nucleotidase becomes more sialylated.

5'-Nucleotidase↗
PubMed1994

A de-sialylated isoform of serum 5'-nucleotidase: clinical and biological significance in hepatobiliary disease.

Using an electrophoretic technique on cellulose acetate, three multiple forms of the 5'-nucleotidase (5'NU) with mobilities alpha 1, alpha 2, and beta appear in the serum of healthy subjects. The difference between the alpha 1 and alpha 2 isoforms lies in their sialylation degree, the alpha 2-5'NU being a de-sialylated form. In 147 patients with different hepatobiliary diseases the alpha 2 isoform was present in only 19% of cases, and there was no significant difference in the activity of total 5'NU, alpha 1-5'NU and beta-5'NU between patients with or without alpha 2-5'NU, alpha 1-5'NU and beta-5'NU (P < 0.001), as with other biochemical indicators of liver damage. It is suggested that in hepatobiliary diseases an increase of the sialylation of serum 5'NU occurs, which would explain the absence of the desialylated alpha 2 isoform in the majority of cases. However, the decrease of hepatic receptors of asialoglycoproteins would lead to an increase of this de-sialylated isoform in the serum of certain patients.

5'-Nucleotidase↗
PubMed1994

Hematofluorometric determination of erythrocyte zinc protoporphyrin: oxygenation and derivatization of hemoglobin compared.

We compared oxygenation and derivatization of hemoglobin for the hematofluorometric determination of erythrocyte zinc protoporphyrin (ZPP). No statistically significant differences were found when the volume ratio of sample to ProtoFluor reagent (which converts hemoglobin to cyanohemoglobin) was changed from 1:1 to 1:4. With the derivatizing reagent, results were significantly higher than those obtained after thorough aeration of the blood sample (P < 0.001). The differences between the results obtained by the two procedures were greater for ZPP values in the reference range. Although the correlation between methods was high (r = 0.997), interconversion of the results by means of the regression equation was not acceptable because the standard error of the estimate from the regression (Syix = 0.36 micrograms/g hemoglobin) was greater than the error acceptable medically (criterion of Harris: Arch Pathol Lab Med 1988; 112:416-20).

Erythrocytes↗
PubMed1992

Changes in alkaline phosphatase and 5'-nucleotidase multiple forms after surgical management of biliary obstruction.

Serial measurements of alkaline phosphatase and 5'-nucleotidase multiple forms in two patients undergoing surgical procedures to release biliary obstruction suggested an inverse relationship between high-M(r) isoforms and serum bile acids concentrations. Furthermore, the study of several groups of patients with cholestatic disorders confirmed this inverse correlation. Mechanisms responsible for these observations are discussed.

5'-Nucleotidase↗
PubMed1991

Electrophoretic separation of 5'-nucleotidase multiple forms.

A procedure is proposed for the separation of multiple forms of 5'-nucleotidase (EC 3.1.3.5) by cellulose acetate electrophoresis. The effects of various treatments (wheat-germ lectin, neuraminidase, n-butanol, papain, Triton X-100 and precipitation of LDL and VLDL) on the electrophoretic pattern of 5'-nucleotidase and alkaline phosphatase were studied. In healthy controls, the presence of three fractions with alpha 1, alpha 2 and beta mobilities was observed, the latter being the major one. In different hepatobiliary diseases a close relationship between the presence of high molecular weight alkaline phosphatase and the increase in the ratio Total/beta 5'-nucleotidase was observed, showing that the increase in total 5'-nucleotidase in these patients is mainly due to the alpha 1 isoform. The nature of these forms is discussed.

5'-Nucleotidase↗
PubMed1990

Evaluation of determination of lactate dehydrogenase isoenzyme 1 by chemical inhibition with perchlorate or with 1,6-hexanediol.

We have evaluated the determination of lactate dehydrogenase (EC 1.1.1.27) isoenzyme 1 activity by chemical inhibition of the other isoenzymes with perchlorate and with 1,6-hexanediol. In the hexanediol method, we studied the effect of the duration of incubation with the inhibitor; a 5-min incubation yielded results closest to those of an immunochemical technique (Isomune-LD). The perchlorate method was the most precise, and the hexanediol method the least, although for none of the techniques did the coefficient of variation exceed the medically acceptable limit prescribed by the College of American Pathologists. Pairwise correlation among the immunoprecipitation, electrophoretic, and chemical inhibition methods was good (r greater than 0.991), although the differences between means were statistically significant (except for the comparison of the two chemical inhibition methods). Because of its ease, low cost, and precision, we recommend the perchlorate method for routine use.

Adult↗
PubMed1990

[Comparison of different procedures for the hemato-fluorometric measurement of erythrocyte zinc-protoporphyrin].

A comparison between procedures for the determination of erythrocyte zinc-protoporphyrin (ZPP) in an AVIV Mod. 206 Haematofluorometer was performed. Initial readings decrease with time, reaching a stability at 6-8 min. This fact cannot be accounted by ZPP photodegradation. High correlation coefficients (r greater than or equal to 0.994) were obtained when values from initial readings were compared with values obtained from readings after ten minutes and with values obtained using saline washed erythrocytes, although in all cases the difference of means were statistically and clinically significant. The use of "ProtoFluor Reagent", which converts haemoglobin to cyanohaemoglobin, led to significantly higher results than those obtained after aeration of the sample, although the correlation between both series of values was also excellent (r = 0.997). No statistically significant differences were found when the ratio sample: ProtoFluor Reagent was changed. These results demonstrate the need for a careful standardization of the operation procedure in the use of the haematofluorometer.

Cyanates↗
PubMed1989

Carnitine deficiency associated with anticonvulsant therapy.

Valproic acid therapy is known to be associated with carnitine deficiency in adult as well as young epileptic patients. In a study of the possible existence of such side-effects with other anticonvulsants, 76.5% of adult patients treated with valproate were deficient in serum free carnitine, with acylcarnitine levels significantly higher than in controls (p less than 0.01), while the carnitine deficiency rate in a group of patients treated with anticonvulsants other than valproate was 21.5%. Since in clinical practice only about one fifth of patients are treated with valproate, this means that about 15% of epileptics are carnitine deficient because of valproate treatment and 17% because of other anticonvulsants. The mechanisms and clinical and biological consequences of the carnitine deficiency associated with antiepileptic drugs other than valproate are not known.

Adolescent↗
PubMed1989

Serum and plasma ceruloplasmin in humans.

In a group of 76 clinically healthy human volunteers, we found a high correlation (r = 0.997, p less than 0.001) between the ceruloplasmin oxidase activities in serum (mean 127.2 U/l) and plasma (mean 124.0 U/l). Similarly high correlation was observed for immunoreactive ceruloplasmin, which was assayed in 65 samples (r = 0.993, p less than 0.001), with means of 306.1 mg/l in serum and 296.4 mg/l in plasma. Although the difference between the means measured in serum and plasma is in both cases statistically significant, it is clinically irrelevant according to the criteria of the College of American Pathologists. Finally, a high correlation between serum and plasma concentrations (r = 0.970, p less than 0.001, N = 32) was also found for acid alpha 1-glycoprotein, whose sialic acid content is greater than that of ceruloplasmin; in this case there was no statistically significant difference between the means. These results suggest that in humans, ceruloplasmin does not bind to erythrocyte and/or platelet membranes via sialyl groups during clotting, which disagrees with the hypothesis of Paynter (Aust. J. Biol. Sci. (1982) 35, 353--361) in cows and sheep.

Adult↗
PubMed1988

Urinary D-glucaric acid and serum hepatic enzyme levels in chronic alcoholics.

Urinary D-glucaric acid (DGA) and the activities of gamma-glutamyl transferase (GGT) and other hepatic enzymes in serum were determined in 33 noncirrhotic male alcoholics who had continued to consume alcohol until at least 24 h prior to the taking of samples. DGA excretion was significantly greater in them than in a group of 30 healthy controls (p less than 0.001), exceeding the upper reference level in 38% of the alcoholic cases (as compared with 88% for GGT). In the alcoholic patients, there was highly significant correlation between urinary DGA and serum GGT (r = 0.613, p less than 0.001), suggesting that in both cases the increased levels are due to enzyme induction. None of the biochemical variables studied were significantly correlated with estimated daily alcohol consumption. Urinary DGA levels fell off rapidly with abstinence, and in 31 alcoholic patients who had consumed no alcohol for 5 days, there was no statistically significant correlation between DGA excretion and serum GGT (r = 0.158, p congruent to 0.4).

Adult↗
PubMed1987

Cord serum gamma glutamyltransferase in newborns.

This article reports correlations among gamma-glutamyltransferase (GGT), fetal haemoglobin (fH), alpha-fetoprotein, 5'-nucleotidase, ceruloplasmin, and direct, indirect, and total bilirubin in the serum of blood taken from the umbilical cords of 128 newborns delivered after 37-42 weeks of gestation. GGT was significantly correlated with alpha-fetoprotein, but not with direct bilirubin, indirect bilirubin, total bilirubin, fH, or %fH. Neither fH nor %fH were correlated with alpha-fetoprotein, but there was highly significant negative correlation between both fH and %fH on the one hand, and gestational age and weight at birth on the other. The %fH was also correlated negatively with ceruloplasmin, which in turn exhibited negative correlation with alpha-fetoprotein. The predominant forms of GGT in umbilical cord and adult sera were, respectively, those with alpha 1 and alpha 2 mobility. In cord sera, delipidation with n-butanol brought about loss of GGT activity and a shift from an alpha 1 to an alpha 2 position, whereas no significant effect of this kind was observed in adult sera. Affinity chromatography through Concanavalin A-Sepharose showed cord sera to contain a proportion of bound-GGT (68.5 +/- 5.5%) that was significantly greater (p less than 0.001) than that found in adult sera (59.8 +/- 10.2%). It is concluded that the high GGT activity of cord sera is probably due to hepatic immaturity rather than maternal sources, enzymatic induction or microsomal lesions; that the predominant form of GGT in cord serum may be a complex with HDL and less sialized than the adult enzyme; and that, of the factors examined, the best indicator of neonatal maturity is fetal haemoglobin.

5'-Nucleotidase↗
PubMed1987

Urinary excretion of D-glucaric acid in porphyria cutanea tarda.

Twenty patients with porphyria cutanea tarda who had ingested no alcohol for at least 10 days before sampling were found to possess urinary D-glucaric acid levels similar to those of 30 clinically healthy controls. Correlation between urinary excretion of D-glucaric acid on the one hand and plasma or urinary porphyrin concentrations on the other was not statistically significant. These results suggest that the high urinary concentrations of D-glucaric acid found in porphyria cutanea tarda patients by Budillon et al. (Acta Hepato-Gastroenterol. 25 (1978) 267) may have been due to recent consumption of alcohol rather than to the porphyrin pathology.

Alcohol Drinking↗
PubMed1982

Serum copper concentration and hepatic enzyme induction during long-term therapy with anticonvulsants.

We evaluated hepatic enzyme induction by measuring urinary D-glucaric acid and serum gamma-glutamyltransferase in a group of 40 adult epileptics of both sexes who were receiving long-term treatment with phenobarbital and (or) phenytoin. Total concentrations of copper and ceruloplasmin in their serum and the oxidase activity of ceruloplasmin were significantly greater than in the control group. However, non-ceruloplasmin copper and specific oxidase activity of the ceruloplasmin (activity per gram) were unchanged. A highly significant relationship was found between gamma-glutamyltransferase and (a) copper (r = 0.682, p less than 0.001), (b) ceruloplasmin (r = 0.523, p congruent to 0.001), and (c) the oxidase activity of the ceruloplasmin (r = 0.598, p less than 0.001). There is also a significant correlation of hemopexin with ceruloplasmin (r = 0.531, p congruent to 0.001) and the oxidase activity of the ceruloplasmin (r = 0.598, p less than 0.001). These results suggest that hypercupremia in patients undergoing long-term anticonvulsant therapy is a direct result of hepatic enzyme induction caused by the drugs that induce synthesis of ceruloplasmin.

Adult↗