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Biomedical subjects

D K Rassin

Publications and source records attributed to D K Rassin.

At least 91 records · Page 5Linked to original sources
PubMed1980

Maternal homocystinuria: studies of an untreated mother and fetus.

A 20-year-old woman with untreated homocystinuria was examined when she was 18 weeks' pregnant. Amniocentesis was performed and raised levels of homocystine and methionine were present in the amniotic fluid. Assay of cystathionine synthetase activity in cultured amniotic fluid cells showed the carrier state for homocystinuria. An abortion was performed because of the possible adverse effects of continuing the pregnancy both for the mother and the fetus. No pathological abnormality was found in the aborted fetus. Further data are needed to assess the possible teratogenic effects of maternal homocystinuria and the adverse consequences of pregnancy in the affected mother.

Abortion, Induced↗
PubMed1980

Carnosinase deficiency: a new variant with high residual activity.

Plasma carnosinase deficiency was discovered in a 12-yr-old male with profound mental retardation, severe athetoid spastic quadriparesis, optic atrophy, sensory peripheral neuropathy, and suprabulbar signs. Amino acid analysis revealed persistent carnosinuria but no detectable carnosinemia. After ingestion of L-carnosine (100 mg/kg), the patient had carnosine in his plasma and excreted 28% of the administered load as carnosine (an agematched control excreted 1.3% as carnosine). Urinary 1-methylhistidine was measurable in the patient and increased greatly during a high anserine diet. Plasma carnosinase activity in the patient was 0.28 mumoles per ml plasma per hr (control mean, 2.00; range, 1.10--2.85), his parents had activity of 1.36 and 1.30, and 2 sibs had activities of 1.10 and 1.86. Carnosinase activity in liver from the patient was 43% of control liver. We have demonstrated that carnosinase activity is present in human nerve and that sural nerve from the patient had activity that was 46% of control nerve. Histopathologic examination of the patient's nerve showed axonal degeneration. Histidine levels in the patient's liver and nerve were normal, and neither beta-alanine nor carnosine was detectable. The unusually high residual carnosinase activity in plasma and tissues from this patient may explain his apparent ability to metabolize anserine and would suggest that this represents a new variant form of carnosinase deficiency. Speculation. Carnosinuria due to plasma carnosinase deficiency may be merely associated with the strinking neurologic findings that have been reported rather than causally related.

Amino Acid Metabolism, Inborn Errors↗
PubMed1979

Fetal tissue amino acid concentrations in argininosuccinic aciduria and in "maternal homocystinuria".

Free amino acid concentrations have been measured in the tissues of a fetus at risk for argininosuccinic aciduria and of an obligate heterozygous fetus in a mother homozygous for homocystinuria. Argininosuccinic acid was detected in all tissues studied of the homozygous affected fetus from the heterozygous mother. Abnormal concentrations of methionine and cystathionine were observed in the tissues of the fetus who was an obligate heterozygote for homocystinuria. These abnormal free amino acid concentrations occur early in fetal development and may be related to later brain dysfunction.

Amino Acid Metabolism, Inborn Errors↗
PubMed1979

Taurine in development and nutrition.

Taurine is an amino acid that is widely distributed in the fluids and tissues of man. In mammals, taurine is a major end-product of methionine metabolism. Taurine is found in most mammalian tissues but is only present in trace amounts in many plants. During fetal development of the brain in man and other mammals taurine is present in high concentrations and declines to lower, adult concentrations during neonatal life. However, during this time there is a net accumulation of taurine when the amount per brain rather than per gram of tissue is calculated. In man, taurine is apparently an essential nutrient, unlike in other animals which have a much greater capacity to synthesize this compound. The human infant, is particular, needs a dietary supply of taurine to synthesize the bile salt taurocholate. Thus, taurine appears to be an important component of the developing brain and must be supplied to man in the diet.

Animals↗
PubMed1979

Argininosuccinic aciduria: prenatal studies in a family at risk.

We have monitored two successive pregnancies in a family which we found to be at risk for argininosuccinic aciduria. We measured argininosuccinic acid (ASA) concentrations in amniotic fluid and utilized an indirect assay of ASA lyase activity in cultured amniotic fluid cells. The assay procedure is based on the uptake of 14C from [14C]citrulline and of [3H]leucine into protein. ASA was easily measured in amniotic fluid from the first fetus at risk, whereas none was detectable in control fluids. Amniotic fluid cells cultured from this fetus had only 5.5% of control ASA lyase activity. The pregnancy was terminated, and hepatic ASA lyase activity in the fetus was shown to be about 1.3% of control values. In addition, eight fetal tissues were analyzed for ASA, and all had significant accumulation. ASA was not detected in amniotic fluid from the second fetus at risk, and ASA lyase activity in cultured cells was 80% of control activity. Enzymatic analysis of erythrocyte lysate confirmed the diagnosis of an unaffected child (ASA lyase = 46% of control) and indicated heterozygosity. Thus, we provide further evidence that argininosuccinic aciduria can be diagnosed successfully in utero by indirect assay of ASA lyase activity in cultured amniotic fluid cells. In addition, high amniotic fluid ASA concentrations provide strong adjunctive evidence for such a prenatal determination, and may prove to be sufficient for diagnosis.

Adult↗
PubMed1978

Taurine deficiency in the kitten subcellular distribution of taurine and [35S]taurine in brain.

Taurine concentration decreases rapidly in the tissues and physiological fluids of kittens fed a diet of partially purified casein which lacks taurine. We have studied the subcellular distribution in cerebrum of taurine and [35S]taurine administered intravenously to these animals. The taurine concentration of all the fractions isolated from the cerebrum of taurine-deficient kittens was approximately sevenfold less than that observed in the fractions of cerebrum isolated from control kittens. The [35S]taurine was approximately twofold greater in all the brain fractions isolated from the taurine-deficient kittens compared with those isolated from the control kittens. The percent distributions of taurine and [35S]taurine in the fractions isolated from the cerebrum of control and deficient kittens were identical. Thus, in the face of a severe diet-induced deficiency of taurine in kitten brain, there appears to be no conservation of taurine by any particular subcellular pool of taurine. These studies provide no evidence for differences in compartmentation of taurine in cerebrum of taurine-deficient kittens compared with control kittens.

Animals↗
PubMed1978

Taurine and other free amino acids in milk of man and other mammals.

Taurine and other free amino acids have been determined in human milk of a number of other species. Taurine is the most abundant free amino acid in the milk of the gerbil, mouse, cat, dog and rhesus monkey. Taurine is the second most abundant amino acid in the milk of the rat, baboon, chimpanzee, sheep, Java monkey and man. Taurine is not a major constituent in the milk of the guinea pig, rabbit, cow and horse. The milk of each species has a characteristic free amino acid pattern which may be an indication of the relative nutritional importance of these compounds during early postnatal development.

Alanine↗
PubMed1978

Taurine deficiency in the kitten: exchange and turnover of [35S] taurine in brain, retina, and other tissues.

Kittens fed a purified diet containing partially-purified casein as the source of protein become taurine-deficient and develop retinal degeneration. The present studies report the exchange and turnover of taurine in different areas of brain, retina and other tissues and fluids of control and taurine-deficient kittens. The various tissues and fluids have different rates of exchange and different half-lives of taurine; taurine deficiency causes a range of changes in these parameters. Generally, tissues and fluids from taurine-deficient kittens accumulated more [35S] taurine and had a longer half-life of taurine than tissues and fluids from control kittens. Nine areas of brain were studied and, of these areas, olfactory bulb had the greatest concentration of taurine. Olfactory bulb resisted taurine depletion to a greater extent than other areas; and, in contrast to other areas of brain, in taurine-deficient kittens, it accumulated [35S] taurine for most of the experiment. Retina resisted taurine depletion and, in taurine-deficient kittens but not in control kittens, it accumulated [35S] taurine throughout the experiment. The amount of taurine conjugated to bile acids was unchanged by the taurine depletion, but the kinetic behavior was altered and was similar to that of retina. The results provide support for the suggestion that, in the kitten at least, taurine is most important for the functions of bile and retina and that taurine depletion affects retina before bile. Taurine may have special importance in olfactory bulb but not necessarily in other regions of brain.

Adrenal Glands↗
PubMed1977

Homocysteine and cysteine loads in patients with homocystinuria due to cystathionine synthase deficiency: effects of vitamin B-6.

The metabolic response of patients with homocystinuria due to cystabhionine synthase deficiency to oral loads of homocysteine indicates: that even severely affected patients with homocystinuria have pools of cystine in their tissues; that control of sulfur amino acid metabolism favors increased concentrations of methionine rather than homocystine in the plasma; and that even patients who apparently are not B-6-responsive respond differently to the loads of homocysteine when challenged during B-6-treatment compared with their response before B-6 treatment. Loading tests with homocysteine indicate that B-6 treatment be of some benefit even in individuals who do not have an obvious biochemical response to such therapy.

Cystathionine beta-Synthase↗
PubMed1977

Free amino acids in liver of patients with homocystinuria due to cystathionine synthase deficiency: effects of vitamin B6.

Patients with homocystinuria due to cystathionine synthase deficiency do not have free homocystine in the liver when it is present in high concentrations in the plasma and the urine. The liver of these patients is capable of maintaining normal concentrations of cystine at a time when the plasma cystine concentration is severely reduced. There is an increase in the methionine concentration of the liver which is reduced to normal concentrations during pyridoxine therapy.

Amino Acids, Sulfur↗
PubMed1977

Milk protein quantity and quality in low-birth-weight infants. III. Effects on sulfur amino acids in plasma and urine.

Well, appropriate-for-gestational age, low-birth-weight infants weighing 2,100 gm or less were divided into three gestational age groups and assigned randomly within each age group to one of five feeding regimens: pooled human milk; formula 1 (F1) = 1.5gm/dl protein, 60 parts bovine whey proteins: 40 parts bovine caseins; F2 = 3.0 gm/dl, 60:40; F3 = 1.5 gm/dl, 18:82; F4=3.0 gm/dl, 18:82. Plasma and urine concentrations of methionine and of cystathionine were higher in the infants fed F1 to F4 than in the infants fed BM. The plasma cystine concentrations of infants fed F2 (which had a cystine content at least twice that of any of the other formulas) were significantly higher than those of infants fed BM. Plasma taurine concentrations of infants fed F1 or F4, which were virtually devoid of taurine, decreased steadily during the course of study becoming lower than those of infants fed BM. Urine taurine concentrations of infants fed F1, F3, or F4 (but not F2 which had more taurine than F1, F3, or F4) were lower than those of infants fed BM. These results provide further evidence for the limited capacity of the preterm human infant to convert methionine to cystine, owing to delayed maturation of cytathionase, and suggest a limited capacity to convert cystine to taurine. The latter suggestion is consistent with low human hepatic cysteinesulfinic acid decarboxylase activity 0.26 (fetal) and 0.32 (adult) nmoles/mg protein/hour vs 468 in rat liver.

Amino Acids, Sulfur↗
PubMed1977

Milk protein quantity and quality in low-birth-weight infants. IV. Effects on tyrosine and phenylalanine in plasma and urine.

Well, appropriate-for-gestational age, low-birth-weight infants were divided into three gestational age groups and assigned randomly within each age group to one of five feeding regimens: pooled human milk (BM); formula 1 (F1) = 1.5 gm/dl protein, 60 parts bovine whey proteins: 40 parts bovine caseins; F2 = 3.0 gm/dl, 60:40; F3 = 1.5 gm/dl, 18:82; F4 = 3.0 gm/dl, 18:82. Plasma and urine concentrations of tyrosine and phenylalanine were far higher in the infants fed F1 to F4, especially F2 and F4, than in the infants fed BM. These findings offer further evidence for the limited capacity of the low-birth-weight infant to catabolize tyrosine. Infants fed F3 had significantly higher plasma tyrosine concentrations than infants fed F1, and those fed F4 had higher concentrations than those fed F2. Thus, increased plasma tyrosine concentrations in low-birth-weight infants are related directly both to the quantity and to the quality of the protein in their diets.

Animals↗