Biomedical subjects
Publications and source records attributed to J Amir.
The occurrence of Down's syndrome in both dizygotic twins appears to be very rare. A case of twins of unlike sex is reported, in which chromosomal analysis showed trisomy 21 in both of them, while the parental karyotypes were normal. This is the third reported case of such a constellation, and the second one in which infant and parental chromosomal analysis was done.
The spinach (Spinacia oleracea) leaf sucrose-phosphate synthase was partially purified via DEAE-cellulose chromatography, and its kinetic properties were studied. Fructose-6-phosphate saturation curves were sigmoidal, while UDPglucose saturation curves were hyperbolic. At subsaturating concentrations of fructose-6-phosphate, 1,5 anhydroglucitol-6-phosphate had a stimulatory effect on enzyme activity, suggesting multiple and interacting fructose-6-phosphate sites on sucrose-phosphate synthase. The concentrations required for 50% of maximal activity were 3.0 millimolar and 1.3 millimolar, respectively, for fructose-6-phosphate and UDPglucose. The enzyme was not stimulated by divalent cations. Inorganic phosphate proved to be a potent inhibitor, particularly at low concentrations of substrate. Phosphate inhibition was competitive with UDPglucose, and its K(i) was determined to be 1.75 millimolar. Sucrose phosphate, the product of the reaction, was also shown to be a competitive inhibitor towards UDPglucose concentration and had K(i) of 0.4 millimolar. The kinetic results suggest that spinach leaf sucrose-phospahte synthase is a regulatory enzyme and that its activity is modulated by the concentrations of phosphate, fructose-6-phosphate, and UDPglucose occurring in the cytoplasm of the leaf cell.
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A giant pigmented nevus (GPN) was present in only one of identical twins. Proof of the identical twinship was based on blood group and HLA system findings. The time of appearance of GPN malformation is assumed to be during early embryologic life. Despite previous opinions to the contrary, we suggest that there is no genetic transmission in GPN.
Aspartic acid concentration in CSF was markedly elevated in a newborn infant with severe, intractable seizures. The levels of all other amino acids in blood, urine, and CSF were within the normal range. Two of the six other siblings in this consanguineous family died in early infancy of a similar condition. Since aspartic acid is a putative excitatory neurotransmitter, a possible causal relationship is suggested between its increased CSF concentration and the occurrence of neonatal convulsions in this family.
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This report makes use of a recent developed method with stable isotope and gas chromatography-mass spectrometry to determine the disappearance of labeled amino acids from plasma samples after iv administration of a single dose (93.3-mumoles/kg body weight) of [15N]glycine (92% N) in neonates. [15N]Glycine measurements were studied three times in each of six preterm infants at different gestational age and twice in two full-term infants. The first study was carried out in all infants 5 to 32 hr after delivery, the second study was performed on the third day of life, and the third study, included only the preterm infants, was at the age of 25 to 29 days. The isotope disappearance curves were linear within the first hr after [15N]glycine administration and represent mainly the hepatic uptake of glycine from the extracellular pool. The volume of glycine pool varied from the day of birth to 4 wk of life. Turnover rate constants of glycine ranging from 1.35 to 2.19 hr-1 were observed in preterm and term infants during the first 32 hr. Significant increases in turnover rate constants were noted on the third day of life in most infants. At 3 to 4 wk of life, statistically significant differences in pool size and turnover rate constants were obtained. An increase of 2- to 3-fold in turnover rate constants was observed as compared to day of birth. Pool sizes declined by 50%, but the resulted fluxes remained almost unchanged during the neonatal period. At the age of 3 to 4 wk, all these infants showed similar kinetic data as in adults.
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This is a report of a patient with chronic monocytic leukaemia with a survival of more than ten years. He was not prone to bacterial infections and his cellular and humoral immunological systems were found to be intact. Ultrastructural study confirmed the monocytic cell type in the bone marrow and peripheral smear.
A case of multiple myeloma with no monoclonal protein synthesis is reported. The patient had hypogammaglobulinemia, bone marrow invasion, osteolytic lesions, and plasma cell tumors. The absence of protein synthesis has been demonstrated in bone marrow culture with tritiated leucine. No evidence of immunoglobulin production was found. Bone marrow or plasma cell tumor biopsy may be the only method of diagnosis in such cases.
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