Biomedical subjects
Publications and source records attributed to B Steinmann.
On routine smears of blood and bone marrow of four patients with GM1 gangliosidosis type I, eosinophil granulocytes were unusually pale and contained faintly stained, unevenly spaced granules some of which were larger than normal and had abnormal ultrastructural appearance. The anomaly may represent a hitherto overlooked but easily obtainable diagnostic marker.
Fumarylacetoacetase was assayed in cultured amniotic fluid cells from four pregnancies at risk for hereditary tyrosinemia and in 11 controls. The enzyme activity was normal in three of the pregnancies at risk for tyrosinemia and healthy children were born. In the fourth case the enzyme activity was deficient, indicating an affected fetus. As the pregnancy was very advanced it was continued, and the child has tyrosinemia. One parent in one of the four families is a compound heterozygote for the tyrosinemia gene and the recently reported "pseudodeficiency" gene for fumarylacetoacetase. This has important consequences for prenatal diagnosis in this family.
We studied tissue and cultured skin fibroblasts from a newborn with the lethal perinatal form of osteogenesis imperfecta born to a mother with the Marfan syndrome and her unrelated husband. Dermis from the infant was thinner and fibril diameter smaller than control; dermal fibroblastic cells had dilated endoplasmic reticulum. His fibroblasts in culture synthesized two different species of pro alpha 1(I) chains in about equal quantity. One chain was normal, the other contained cysteine within the triple-helical portion of the COOH-terminal cyanogen bromide peptide alpha 1(I)CB6. Molecules which contained two copies of the mutant chain formed alpha 1(I)-dimers linked through interchain disulfide bonds. Molecules which contained either one or two mutant chains were delayed in secretion and underwent excessive lysyl hydroxylation and hydroxylysyl glycosylation of all chains in the molecule, probably as a result of delayed triple-helix formation. Molecules containing either one or two copies of the mutant chain melted at 38 degrees C instead of 41 degrees C. The most likely explanation for these findings is that a cysteine is substituted for a glycine in the triple-helical domain of the products of one of the alpha 1(I) alleles. Such a substitution would interfere with triple-helix formation and stability and thus explain 1) the decreased melting temperature, 2) the increased post-translational modification, 3) the altered rate of secretion and accumulation of intracellular material, 4) the increased intracellular degradation of newly synthesized collagen, and 5) the decreased collagen production. Since neither parental cell strain produced the same mutant chain, the findings are best explained by a new mutation in one of the alpha 1(I) genes. The role of the uncharacterized "Marfan" gene in modifying the phenotype in this patient is unclear.
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Two siblings born to consanguineous parents are reported with typical clinical features of the Ehlers-Danlos syndrome type IV. However, their cultured skin fibroblasts synthesize and secrete procollagen type III in normal amounts and proportions. This is probably a new form of the Ehlers-Danlos syndrome with autosomal recessive inheritance classified as Ehlers-Danlos syndrome type IV D.
In galactosemic subjects, treatment prevents liver and kidney failure, brain damage and cataracts, but total exclusion of galactose from the diet does not ensure the absence of all pathology. Early and well-treated children show satisfactory general health and growth, make reasonable though suboptimal intellectual progress, are prone to speech defects, and commonly experience visual perceptual difficulties and some social maladjustment. Two different metabolites are potentially toxic: galactitol is responsible for the cataracts while galactose-1-phosphate causes the rest of the pathology. As both metabolites are present in the fetus and in postnatal life, pathological changes may develop at any time in life, even when treatment is strict. Owing to UDP-galactose 4'-epimerase, man can generate galactose from glucose from early embryonic life on. Therefore, transferase-deficient individuals can form galactose-1-phosphate in the absence of exogenous galactose, a process for which UDP-glucose pyrophosphorylase is essential. Biosynthesis of galactose from glucose in well-treated galactosemics constitutes a mechanism of self-intoxication, not only in utero but also in adult life. The prognosis for some treated galactosemics may depend on their own ability to limit this process. Galactosemic girls, whether well-treated or not, run a considerable risk of developing ovarian dysfunction. Hypergonadotropinism has been diagnosed from 2 years of age to the third decade. Prenatal ovarian failure is not excluded but the observed facts suggest that ovarian failure is acquired after ovarian differentiation and initiation of folliculogenesis, at an individual rate and possibly through continuous self-intoxication with galactose-1-phosphate. Up to now, mild hypergonadotropinism has been documented in only 2 galactosemic males, but the male cohort of galactosemics studied for gonadal dysfunction is yet small.
We studied neutrophil microbicidal function and oxidative metabolic activity in a patient with glycogenosis Ib. The intracellular killing defect and the respiratory burst abnormality in gycogenosis Ib neutrophils were confirmed. The impaired oxygen-dependent microbicidal activity was shown to result from impaired hexose monophosphate shunt activity (impaired endogenous NADPH synthesis) and could be corrected by homogenization of the cells, followed by the addition of exogenous NADPH. Our data are thus consistent with a possible role for glucose-6-phosphate transport in neutrophil microbicidal function. We recommend a continuous prophylaxis with co-trimoxazole in patients with glycogen storage disease Ib.
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We describe a study of a boy with neonatal severe primary hyperparathyroidism (NSPHP) and alkaptonuria born to related parents of Turkish origin. The clinical and chemical courses (e.g. of mineral metabolism, of urinary excretion of amino acids and collagen metabolites) in response to various therapeutic approaches including total parathyroidectomy (PTX) are reported. Urinary excretion of calcium was unusually low before and immediately after PTX, and later during an inadvertent vitamin D intoxication. It corresponded to values typical for patients with familial hypocalciuric hypercalcemia (FHH), an autosomal dominant disorder. Both parents and one sibling had episodes of hypercalcemia with inappropriately high parathormone levels; in the father there was also relative hypocalciuria consistent with FHH. On the basis of the genetic and pathophysiologic data reported here, we speculate that homozygosity for the 'FHH-gene' is the cause of the life-threatening manifestation of NSPHP, whereas heterozygosity for the same gene leads to FHH, by comparison a mild disorder. The association of the two very rare recessively transmitted disorders, alkaptonuria and NSPHP, is unique; close linkage of the two genes, one coding for homogentisic acid oxidase, the other for the unknown gene product defective in NSPHP, can be suspected.
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In the kidneys of two infants who died from glycogenosis type II (deficiency of lysosomal acid alpha-glucosidase) the activity of alpha-glucosidase at acid pH was absent only from the medulla but not the cortex. This prompted an investigation of acid and neutral alpha-glucosidases of the two zones of normal human kidney and of liver. In the kidney medulla, a single, fast migrating electrophoretic band was active at neutral but not at acid pH. In the cortex, three additional bands were detected at neutral pH and two in the liver. One slowly migrating band was unique to the cortex and active over a broad pH range. It had comparatively high sensitivity to the inhibitor turanose and high heat stability. Its properties suggested a close relationship or identity to glucoamylase of the intestinal brush border membrane and to alpha-glucosidase in leukocytes and amniotic fluid and cells.
Collagen production by cultured human lung fibroblasts was examined when the cells were made deficient in ascorbate. Cells grown in the absence of ascorbate produced 30% less collagen during a 6-h labeling period than cells incubated with as little as 1 microgram/ml ascorbate during the labeling period. Cells grown without ascorbate produced under-hydroxylated collagen which was subject to increased intracellular degradation from a basal level of 16% to an enhanced level of 49% of all newly synthesized collagen. The likely mechanism for increased intracellular degradation is the inability of under-hydroxylated collagen to assume a triple-helical conformation causing it to be susceptible to intracellular degradation. Measurement of collagen production by enzyme linked immunoassay (ELISA) using antibodies directed against triple-helical determinants of collagen showed that both types I and III collagens were affected. In contrast, another connective tissue component, fibronectin, was not affected. Analysis by ELISA showed a greater decrease in collagen production than did analysis by the collagenase method, suggesting that some non-helical collagen chains (detected by collagenase but not by ELISA) were secreted in the absence of ascorbate. These results provide a mechanism to account, in part, for the deficiency of collagen in connective tissues which occurs in a state of ascorbate deficiency.
Appendectomy was performed in a 14 1/2-year-old boy with undiagnosed hereditary fructose intolerance because of chronic recurrent abdominal pain. During and after operation fructose containing solutions were infused. The patient received a total of 250 g fructose intravenously over 30 hours. Hours after onset of infusion he became soporous, hypoglycaemic and acidotic and was anuric after one day. Although the diagnosis was suspected by the end of the first postoperative day and fructose had been cancelled and haemodialysis been started, the boy died after a further 3 days with signs of acute kidney and liver failure. The diagnosis of hereditary fructose intolerance was biochemically established in post mortem liver tissue. This case recalls the fact that fructose, sorbitol or invert sugars should not be added to infusion solutions as they may be toxic for healthy persons and imply a lethal risk for patients with undiagnosed hereditary fructose intolerance, even well beyond the baby and infant period.
1. The metabolic fate of orally given deuterated L-tyrosine, 50 mg/kg body weight, was investigated in seven patients with tyrosinemia type I in order to obtain evidence that the primary defect is at the level of fumarylacetoacetase. 2. The absence of fumarylacetoacetase could be proved in liver biopsy specimens obtained from four patients. 3. All patients excreted deuterated succinylacetoacetate and deuterated succinylacetone was detected in six out of seven. The total amount of these compounds was rather low; maximal 8.3% of the dose. The peak of the excretion occurred 3-6 h after loading, indicating an endogenous formation of the metabolites. 4. All patients excreted deuterated 4-hydroxyphenyl acids, probably reflecting secondary 4-hydroxyphenylpyruvate dioxygenase deficiency connected with liver damage. 5. No evidence for other secondary routes of tyrosine metabolism was found.
Cultured skin fibroblasts from two siblings with hepatic glycogen synthetase deficiency and from their parents contained glycogen synthetase activity which was within the range of the controls. The mutation was thus not expressed in fibroblasts, a finding further documenting the presumed existence of genetically different forms of glycogen synthetase.
In rats with adjuvant-induced arthritis, the effect of (+)-catechin (CA) and 0-(beta-hydroxyethyl) rutosides (HR) on the crosslinking of collagen was studied. Compared with controls the arthritic group showed an increase in the reversibility of neutral salt-soluble collagen gel, solubility of acid-insoluble collagen to denaturing agents and the ratio of alpha/beta subunits of neutral salt-soluble collagen. These results suggest an impaired maturation of collagen in arthritic animals. Administration of CA or HR to the arthritic animals caused a decrease in the reversibility of collagen gel and in the solubility of acid-insoluble collagen to denaturing agents and to pronase. In addition, the electrophoretic patterns of neutral salt-soluble collagen on SDS polyacrylamide gels also showed a decrease in the alpha/beta ratio. All these results may collectively indicate that both flavonoids promote the crosslinking of collagen in arthritic animals.