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J C Hafkenscheid

Publications and source records attributed to J C Hafkenscheid.

72 records · Page 4Linked to original sources
PubMed1977

Influence of bile acids on the (Na+-K+)-activated- and Mg2+-activated ATPase of rat colon.

The influence of various bile acids on the (Na+-K+)-ATPase and Mg2+-ATPase activity of rat colon is described. At a concentration of 0.6 mmol/l C and TC did not inhibit the (Na+-K+)-ATPase activity in contrast to GC. The taurine derivates TC, TCDC and TDC did not influence or even enhanced the (Na+-K+)-ATPase activity. All bile acids except C, TC and CDC depressed the Mg2+-ATPase activity. At higher concentrations only C and TC did not influence the (Na+-K+)-ATPase activity. C, GC and TC at 2.5 mmol/l decreased the (Na+-K+)-activated phosphatase with ATP as substrate. All other substrates tested did not influence the enzymic activity significantly. The results indicate that bile acids can inhibit the Na+-absorbing system in rat colon. Hence this inhibition can cause diarrhea.

Adenosine Triphosphatases↗
PubMed1977

Serum versus heparinized plasma for alanine aminotransferase and aspartate aminotransferase of normal individuals.

The influence of heparin on the estimation of aminotransferases was investigated in a reaction medium containing phosphate or Tris buffer. Heparin scarcely affects the ASAT determination, but the ALAT activity in plasma is about 70% of the activity in serum, when the enzyme determination is carried out in Tris buffer. There exists a lag phase due to which the decrease in absorbance with the incubation time is nonlinear. When the Tris buffer is omitted, the same lag phase is observed in the ALAT determination. This lag phase is not caused by the indicator enzyme LDH. Addition of phosphate to the incubation medium without any buffer abolishes this lag phase. The possibility exists that heparin influences the structure of the proteins present in plasma and that these proteins, in their turn, decrease the enzymatic activity of ALAT.

Alanine Transaminase↗
PubMed1977

Determination of the activity of aminotransferases: comparison of two buffer systems with and without supplementary pyridoxal-5'-phosphate.

A comparison was made between the aminotransferase activities of a number of plasma or serum samples in 4 reaction media: phosphate buffer, phosphate buffer + pyridoxal-5'-phosphate, tris buffer and tris buffer + pyridoxal-5'-phosphate. The reactions were carried out in the various buffer systems on the same day at 35 degrees C on an automatic kinetic enzyme system (AKES, Vitatron, Dieren, the Netherlands). The highest enzymic activity of both aminotransferases is observed in tris buffer + pyridoxal-5'-phosphate. The activity is about 10--15% higher than in phosphate buffer + pyridoxal-5'-phosphate. Without supplementary pyridoxal-5'-phosphate the differences between both buffer systems are lower or absent. It appears necessary, therefore, to determine the activity of both aminotransferases in a buffer system with tris and to add pyridoxal-5'-phosphate, since assays should be carried out in the presence of optimal concentrations of any of the necessary factors.

Alanine Transaminase↗
PubMed1977

Serum albumin levels in patients with the Zollinger-Ellison syndrome.

Serum albumin concentrations in 20 patients with proved or presumed Zollinger-Ellison (ZE) syndrome (4.1 +/- 0.8 g per 100 ml; mean +/- SD) were significantly (P less than 0.01) lower than the levels observed in 40 normal controls (5.1 +/- 0.3 g per 100 ml), 40 duodenal ulcer patients (5.1 +/- 0.4 g per 100 ml), and 20 stomal ulcer patients (5.1 +/- 0.3 g per 100 ml). Six ZE patients with metastatic gastrinoma had slightly lower (P less than 0.10) serum albumin concentrations (3.5 +/- 0.9 g per 100 ml) than did 14 ZE patients without evidence of metastatic lesions (4.3 +/- 0.7 g per 100 ml). In a small group of patients studied more extensively, the mechanism of hypoalbuminemia was found to be complex. In addition to metastatic tumor growth, both gastrointestinal protein loss and impaired albumin synthesis may be factors in the pathogenesis of hypoalbuminemia. Inadequate nutrition was only evident in 1 patient with esophageal stricture and in 2 patients with extensive tumor growth after total gastrectomy. Total gastrectomy induced a rise in serum albumin in all 8 patients studied (P = 0.01). It is concluded that low serum albumin concentrations in peptic ulcer patients may be a clue to the diagnosis of ZE syndrome.

Adolescent↗
PubMed1975

An enzymic method for the determination of the glycine/taurine ratio of conjugated bile acids in bile.

A method is described in which the ratio of the glycine- to taurine-conjugated bile acids (G/T ratio) in bile is determined. After pretreatment of the bile for removal of the lipids, the bile acids are deconjugated enzymically with choloylglycine hydrolase (EC 3.5.1.24). The amino acids taurine and glycine are liberated in this way, after appropriate isolation, taurine and/or glycine are then determined with ninhydrin, enabling the establishment of the G/T ratio. A nearly complete hydrolysis was obtained for 6 conjugated bile acids, while the recovery of these acids when added to hog or ox bile was quantitative. The mean G/T ratio for hog bile, ox bile and human B-bile was 6.3, 2.5 and 2.0, respectively. The amount of total, free and conjugated bile acids can be determined by this method, combined with the 3alpha-hydroxysteroid dehydrogenase technique for bile acid determination described by Iwata and Yamasaki [1]. A high G/T ratio was observed in 3 cases of Crohn's disease in the small bowel, but the extent of deconjugation in B-bile was lower than in duodenal fluid. The determination of the G/T ratio can be complementary to our knowledge of the metabolism of bile salts in certain gastro-intestinal disorders.

Amidohydrolases↗
PubMed1975

Standardization of the alkaline phosphatase determination with human placental phosphatase.

The influence of changes in temperature and salt concentrations on the enzymic activity of 3 different alkaline phosphatase preparations has been examined. Beef liver phosphatase is labile; the activity is already lost by lyophilization. Hog intestinal and especially human placental phosphatase are more stable. In contrast to reconstituted sera no preincubation is necessary to restore the enzymic activity. A lyophilized human placental phosphatase, kept at room temperature, showed no change in activity in a period of about one year. A mean value of enzymic activity of 133 U/l was observed with a coefficient of variation of 2.4% for 12 determinations. It is suggested to assign a value to such a preparation and to use it as a primary standard in the determination of the alkaline phosphatase.

Alkaline Phosphatase↗
PubMed1975

Important role of tryptophan on albumin synthesis in patients suffering from anorexia nervosa and hypoalbuminemia.

The rate of albumin synthesis and the serum levels of amino acids were measured in three patients suffering from anorexia nervosa. In comparison to the control group the rate of albumin synthesis was lower for the two patients with hypoalbuminemia and the serum levels of valine, isoleucine and tryptophan also were decreased. Intravenous administration of tryptophan alone failed to increase the serum albumin level in one patient. In another patient, a 3-week period of infusion of amino acids without tryptophan failed to correct the rate of albumin synthesis or the serum albumin level. The serum albumin level rose from 37.1 g/liter to 46.8 g/liter after the infusion of amino acids plus tryptophan. The reduced supply of amino acids as the most important factor in the decrease in albumin synthesis and the important role of tryptophan in the regulation of albumin synthesis are discussed.

Adult↗
PubMed1975

Estimation of radiation dosage and transmutation effect of 14-C involved in measuring rate of albumin synthesis with 14-C-carbonate.

For direct measurement of the rate of albumin synthesis Na2 14CO3 was used intravenously. The assessment of the radiation hazard involved in the study was based on the knowledge of the minimum dose of Na214CO3 necessary for a sufficient incorporation of 14C in the guanidine-C of arginine in albumin to obtain measurable radioactivity. By measurement of expired 14CO2 and excreted 14C-urea in the urine during a 5-hr period following intravenous administration of Na214CO3 in five subjects, some quantitative data on 14C retention and radiation dosage were obtained. In comparison with animal studies, the rate of expiration of 14CO2 in man is slower. About 50% of the total radioactivity injected was lost through the respiratory route in the first hour. The total amount of expired 14C during the 5 hr of investigation was about 75% of the injected dose for the five subjects. The amount of 14C excreted as urinary 14C-urea during the 5 hr of investigation is very small in comparison with the expired 14C; it was only about 0.5% of the dose injected. The total absorbed radiation dose after complete elimination of 14C from the body was calculated with various assumptions. The extra risk of genetic damage due to disintegration of retained 14C in comparison with that of natural 14C in the body during 30 living years is about 50%.

Albumins↗