Ontogeny of hepatic enzymes involved in serine- and folate-dependent one-carbon metabolism in rabbits.

Serine occupies a central position in folate-dependent, one-carbon metabolism through 5,10-methylenetetrahydrofolate (MTHF) and 5-formyltetrahydrofolate (FTHF). We characterized the ontogeny of the specific activity of key enzymes involved in serine, 5,10-MTHF, and 5-FTHF metabolism: methenyltetrahydrofolate synthetase (MTHFS), MTHF reductase (MTHFR), the glycine cleavage system (GCS), methionine synthase (MS), and serine hydroxymethyltransferase (SHMT) in rabbit liver, placenta, brain, and kidney. In liver, MTHFS activity is low in the fetus (0.36 +/- 0.07 nmol. min(-1). mg protein(-1)), peaks at 3 wk (1.48 +/- 0.50 nmol. min(-1). mg protein(-1)), and then decreases to adult levels (1.13 +/- 0.32 nmol. min(-1). mg protein(-1)). MTHFR activity is highest early in gestation (24.9 +/- 2.4 nmol. h(-1). mg protein(-1)) and declines rapidly by birth (4.7 +/- 1.3 nmol. h(-1). mg protein(-1)). MS is highest during fetal life and declines after birth. Cytosolic SHMT activity does not vary during development, but mitochondrial SHMT peaks at 23 days. GCS activity is high in the fetus and the neonate, declining after weaning. In placenta and brain, all activities are low throughout gestation. Cytosolic and mitochondrial SHMT activities are low in kidney and rise after weaning, whereas MTHFS is low throughout development. These data suggest that the liver is the primary site of activity for these enzymes. Throughout development, there are multiple potential sources for production of 5,10-MTHF, but early in gestation high MTHFR activity and low MTHFS activity could reduce 5,10-MTHF availability.

(-)-Hydroxycitric acid does not affect energy expenditure and substrate oxidation in adult males in a post-absorptive state.

OBJECTIVE: (-)-Hydroxycitric acid ((-)-HCA) is available as a herbal supplement, and promoted as a weight loss agent. It is hypothesized that (-)-HCA can increase fat oxidation by inhibiting citrate lyase, an enzyme which plays a crucial role in energy metabolism during de novo lipogenesis. The indirect inhibition of the cytosolic pool of citrate by (-)-HCA and the subsequent reduction in acetyl coenzyme A and oxaloacetate alters steps in the citric acid cycle that promote fat oxidation. The objective of this study was to determine the effect of (-)-HCA on marker substrates of altered metabolism, as well as on respiratory quotient (RQ) and energy expenditure (EE) in humans, following an overnight fast and during a bout of exercise. HYPOTHESIS OF STUDY: We hypothesized that supplementation with (-)-HCA would result in an increase in fat oxidation and metabolic rate, reflected by an increase in beta-hydroxybutyrate and EE and/or a decrease in RQ. Furthermore, during moderately intense exercise, we hypothesized that (-)-HCA supplementation would increase the rate of lactate conversion to glucose in the liver, with a subsequent reduction of circulating lactate and an elevation of circulating ketone bodies due to the increased partial oxidation of fatty acids (FA) in mitochondria. Studies have examined the fat regulating action of (-)-HCA on steps of the citric acid cycle in rodents showing reductions in body weight and food intake. No studies have investigated the effects of (-)-HCA supplementation in conjunction with a typical daily dietary composition (that is approx 30-35% fat) on metabolic processes which could influence body weight regulation in humans. DESIGN: This was a double blind, placebo controlled, randomized, crossover study involving three days of (-)-HCA (3.0 g/d) or placebo supplementation. The effects of (-)-HCA supplementation on metabolic parameters with or without moderately intense exercise was studied over four laboratory visits. SUBJECTS: Sedentary adult male subjects (n = 10, age: 22-38 y, body mass index (BMI) 22.4-37.6 kg/m2). MEASUREMENTS: Two of the four visits involved no exercise (Protocol A) with and without (-)-HCA treatment, while the remaining two visits included a moderately intense exercise bout (Protocol B; 30 min at 40% maximal aerobic fitness (VO2max) and 15 min at 60% VO2max) with and without (-)-HCA treatment. EE (by indirect calorimetry) and RQ were measured for 150 min following an overnight fast. Blood samples were collected for the determination of glucose, insulin, glucagon, lactate, and beta-hydroxybutyrate concentrations. RESULTS: In a fasted state and following 3 d of (-)-HCA treatment, RQ was not significantly lowered during rest (Protocol A) nor during exercise (Protocol B) compared with the placebo treatment. Treatment with (-)-HCA did not affect EE, either during rest or during moderately intense exercise. Furthermore, the blood substrates measured were not significantly different between treatment groups under the fasting conditions of this study. CONCLUSION: These results do not support the hypothesis that (-)-HCA alters the short-term rate of fat oxidation in the fasting state during rest or moderate exercise, with doses likely to be achieved in humans while subjects maintain a typical Western diet (approx 30-35% total calories as fat).

Partial splenic embolization in five children with hypersplenism: effects of reduced-volume embolization on efficacy and morbidity.

PURPOSE: To evaluate the effects of reducing the volume of spleen infarcted during partial splenic embolization (PSE) for treatment of hypersplenism in children. MATERIALS AND METHODS: Five children with hypersplenism underwent embolization of 30%-40% of the splenic volume. The results were compared with those of a previous study of 70%-80% PSE performed in 17 children. RESULTS: The hospital stay after the procedure was reduced from 16.0 days +/- 8.0 to 6.6 days +/- 5.6. The febrile period decreased from 15.0 days +/- 8.1 to 5.0 days +/- 6.6. The peak white blood cell count was 8,300/mm3 +/- 4,600 (8.3 x 10(9)/L +/- 4.6) versus 19,400/mm3 +/- 7,800 (19.4 x 10(9)/L +/- 7.8) in the earlier study. The peak platelet count was 153,000/mm3 +/- 65,000 (153 x 10(9)/L +/- 65) versus 636,000/mm3 +/- 406,000 (636 x 10(9)/L +/- 406). The platelet count after a mean follow-up of 14 months was 70,000/mm3 +/- 7,000 (70 x 10(9)/L +/- 7) versus 230,000/mm3 +/- 62,000 (230 x 10(9)/L +/- 62) after a mean follow-up of 45 months. The frequency of variceal hemorrhage decreased from 3.5 to 0.5 episodes per year. The frequency of epistaxis decreased from 30 to 15 episodes per month. CONCLUSION: Reduced-volume embolization decreased morbidity. All patients maintained a platelet count above baseline, and no patient required repeat embolization.

Identification of a new inborn error in bile acid synthesis: mutation of the oxysterol 7alpha-hydroxylase gene causes severe neonatal liver disease.

We describe a metabolic defect in bile acid synthesis involving a deficiency in 7alpha-hydroxylation due to a mutation in the gene for the microsomal oxysterol 7alpha-hydroxylase enzyme, active in the acidic pathway for bile acid synthesis. The defect, identified in a 10-wk-old boy presenting with severe cholestasis, cirrhosis, and liver synthetic failure, was established by fast atom bombardment ionization-mass spectrometry, which revealed elevated urinary bile acid excretion, a mass spectrum with intense ions at m/z 453 and m/z 510 corresponding to sulfate and glycosulfate conjugates of unsaturated monohydroxy-cholenoic acids, and an absence of primary bile acids. Gas chromatography-mass spectrometric analysis confirmed the major products of hepatic synthesis to be 3beta-hydroxy-5-cholenoic and 3beta-hydroxy-5-cholestenoic acids, which accounted for 96% of the total serum bile acids. Levels of 27-hydroxycholesterol were > 4,500 times normal. The biochemical findings were consistent with a deficiency in 7alpha-hydroxylation, leading to the accumulation of hepatotoxic unsaturated monohydroxy bile acids. Hepatic microsomal oxysterol 7alpha-hydroxylase activity was undetectable in the patient. Gene analysis revealed a cytosine to thymidine transition mutation in exon 5 that converts an arginine codon at position 388 to a stop codon. The truncated protein was inactive when expressed in 293 cells. These findings indicate the quantitative importance of the acidic pathway in early life in humans and define a further inborn error in bile acid synthesis as a metabolic cause of severe cholestatic liver disease.

Autoradiographic measurement of tyrosine hydroxylase immunoreactivity in rat brain using enhanced chemiluminescence: a general method for combined quantitative and cytochemical detection.

Autoradiographic measurements of peroxidase labelled tyrosine hydroxylase immunoreactivity in brain sections from rats with unilateral 6-hydroxydopamine lesions were obtained using enhanced chemiluminescence. The autoradiograms required only 5-60 s exposure and displayed a good signal-to-noise ratio. The autoradiograms were quantitated using densitometry and by comparison with a standard curve. Following acquisition of the autoradiograms the sections were stained with the chromogen diaminobenzidine (DAB). Distribution of the DAB closely followed the grain densities observed in the autoradiograms on both the lesioned and unlesioned side of the brain. This method represents a simple, rapid and inexpensive technique for performing both quantitative autoradiography and cytochemical studies in individual tissue sections of any peroxidase labelled immunoreactivity.

The results of surgical treatment of cancer of the rectum by radical resection and extended abdomino-iliac lymphadenectomy.

At St Mark's Hospital survival after radical surgery for cancer of the rectum has not changed significantly over the past 30 years. The technique of extended abdomino-iliac lymphadenectomy was developed in an attempt to improve prognosis in patients considered to have particularly unfavourable tumours. Between 1960 and 1981 the technique was used in 75 patients with a single adenocarcinoma of the rectum. Two patients died postoperatively and 52 patients developed complications; a mortality and morbidity similar to those seen after conventional surgery at this hospital. Five-year survival rate showed no improvement over that achieved by conventional techniques; disappointingly this was also the case for patients with Dukes' C1 tumours. The results of this study suggest that an improvement in survival in patients with cancer of the rectum is unlikely to be achieved by any extension of conventional radical surgery.

Gardner's syndrome and steatocystoma multiplex. Two unusual genetically determined conditions occurring in same patient.

A 43-year-old man is described who had Gardner's syndrome and steatocystoma multiplex. These two unusual genetically determined conditions were associated because he had inherited the Gardner's syndrome from his father and the steatocystoma multiplex from his mother.