Synthesis and maturation of cross-reactive glycoprotein in fibroblasts deficient in arylsulfatase a activity

The biosynthesis of arylsulfatase A was studied in cultured fibroblasts by pulse-chase labeling with [2-³H]mannose; the enzyme was isolated by immunoprecipitation and denaturing polyacrylamide gel electrophoresis. In normal fibroblasts, and in fibroblasts from a patient with multiple sulfatase deficiency, the enzyme was synthesized as a glycoprotein of apparent molecular weight of 59,000; half of it was processed over a period of 4 days to M_r= 57,000. The precursor chain of M_r= 59,000 was secreted in the presence of 10 mM NH₄Cl. An immunoprecipitable glycoprotein of normal size was synthesized by fibroblasts from two unrelated patients with metachromatic leukodystrophy, but this material disappeared within twenty hours. In fibroblasts from an individual with pseudodeficiency of arylsulfatase A, the immunoprecipitable precursor glycoprotein was smaller (M_r= 56,000). The synthesis of cross-reactive proteins with altered properties supports the concept of allelic mutations as the genetic basis of metachromatic leukodystrophy and of arylsulfatase A pseudodeficiency.     

Effect of a potassium-deficient diet on arterial blood pressure, plasma and tissue cations, and tissue norepinephrine in the hypertensive dog

Chronic potassium deficiency in one-kidney one-clip hypertensive dogs significantly reduces blood pressure and plasma potassium, with a simultaneous increase in plasma renin activity. Tissue potassium concentration was decreased and tissue sodium concentration was increased in striated muscle and adrenal glands, which may suggest that the sodium-potassium pump was inhibited. In myocardium the sodium concentration was higher but the potassium concentration was not significantly lower than in control hypertensive dogs on normal diets. Arterial cation concentrations in the potassium-deficient group were not significantly different from those in the control group. Tissue norepinephrine concentration was higher in arteries from potassium-deficient animals, significantly so in the mesenteric and femoral arteries. The conclusion is that potassium deficiency may decrease blood pressure in the one-kidney one-clip hypertensive dogs by impairing the release of norepinephrine.     

Processing of the Encephalomyocarditis Virus Capsid Precursor Protein Studies in Rabbit Reticulocyte Lysates Incubated with N-Formyl-[35S]Methionine-tRNAfMet

Translation of encephalomyocarditis virus RNA in rabbit reticulocyte lysates in the presence of N-formyl-[(35)S]methionine-tRNA(f) (Met) revealed that a small polypeptide is cleaved from the N-terminus of the capsid protein precursor, preA, by virus-coded protease activity. Therefore, this N-terminal segment comprising the translation initiation site is not conserved in any of the mature capsid proteins.     

The biochemical and ultrastructural effects of tunicamycin and D-glucosamine in L1210 leukemic cells

Tunicamycin was found to specifically inhibit the incorporation of a number of sugars into L1210 leukemia cell glycoproteins. This inhibition of glyco-protein biosynthesis led to a cessation of cell growth which was reversible in a dose-dependent and time-dependent manner. After removal of the antibiotic from L1210 cell cultures resumption of sugar incorporation preceded that of thymidine incorporation and the recovery of cell growth. The treatment of cells with tunicamycin resulted in a significant increase in the intracellular pool of UDP-N-acetylglucosamine which occurred concurrently with alterations in cell ultrastructure including distentions of the endoplasmic reticulum and nuclear membranes. Similar ultrastructural changes and increases in the intracellular pools of UDP-sugars were observed in L1210 cells exposed to 5 mM D-glucosamine, which suggested that the antiproliferative effects of tunicamycin may be related to the accumulation in the endoplasmic reticulum of one or more nucleotide sugar precursors of asparagine-linked glycoprotein biosynthesis. However, the biological effects of tunicamycin could be distinguished from those caused by D-glucosamine. Exposure of L1210 cells to tunicamycin resulted in specific alterations in the biochemical composition of the plasma membrane and in the inhibition of cellular agglutination by wheat germ agglutinin which were not apparent following exposure to equitoxic concentrations of the aminosugar. These studies, together with those which demonstrated that recovery of the cellular capacity to synthesize glycoproteins was obligatory for the recovery of cellular proliferation in tunicamycin-treated cells, suggested that inhibition of the synthesis of glycoproteins was the major factor limiting L1210 leukemic cell proliferation.     

Glycosyl acceptors in intact and permeabilized normal and cystic fibrosis fibroblasts

Using cell permeabilization, a technique which allows addition of exogenously supplied radiolabeled sugar nucleotides to serve as direct glycosyl donors, oligosaccharide biosynthesis was examined in fibroblasts obtained from normal and cystic fibrosis (CF) subjects. Incubation of logarithmically growing cells with either radiolabeled leucine or xylose has indicated that there was a difference in the synthetic rate between the cell types. Protein synthesis in normal cells made permeable with 50 m?g/ml lysolecithin (LL) was demonstrated to be absent, and could not be induced to take place by adding exogenous components, including energy sources and amino acids, normally required for protein synthesis. Thus radiolabeled sugars were being added to peptide acceptors which were already present at the time of LL addition. Both permeable and intact fibroblasts were exposed to labeled UDP-xylose, UDP-galactose, and UDP-glucuronic acid, all donors of mucopolysaccharide precursors. The uptake of xylose into protein was the same for both normal and CF cells, but permeable CF fibroblasts incorporated statistically greater amounts of sugar from UDP-galactose and UDP-glucuronic acid. Intact CF cells were also labeled using these two sugar nucleotides. Trypan blue exclusion indicated CF and normal fibroblasts were equally intact. This and the fact that preincubation of CF cells with the appropriate cold sugar nucleotide eliminated the differences in incorporation between the normal and CF cells suggested that CF fibroblasts had more cell surface acceptor than the normal cells.     

Some factors affecting spore replication of Nosema algerae (Microspora,Nosematidae) in Pieris brassicae (Lepidoptera)

The production of Nosema algerae spores was examined in Pieris brassicae. Spore replication in the insect host followed a logistic pattern of development. The factors studied which affected spore production and replication were dose level (5 × 10², 5 × 10³, and 5 × 10⁴ spores per insect), larval instar (fourth and fifth), and cool pretreatment of the insects at 20°C prior to inoculation compared with a constant temperature of 26°C. A three-way analysis showed the interactions between these factors. The logistic pattern of spore replication was used to explain the results.     

Cultural Aspects of Health and Illness Behavior in Hospitals

Health care attitudes reflect the basic world view and values of a culture, such as how we relate to nature, other people, time, being, society versus community, children versus elders and independence versus dependence. Illness behavior determines who is vulnerable to illness and who agrees to become a patient—since only about one third of the ill will see a physician. Cultural values determine how one will behave as a patient and what it means to be ill and especially to be a hospital patient. They affect decisions about a patient''s treatment and who makes the decisions. Cultural differences create problems in communication, rapport, physical examination and treatment compliance and follow through. The special meaning of medicines and diet requires particular attention. The perception of physical pain and psychologic distress varies from culture to culture and affects the attitudes and effectiveness of care-givers as much as of patients. Religious beliefs and attitudes about death, which have many cultural variations, are especially relevant to hospital-based treatment. Linguistic and cultural interpreters can be essential; they are more available than realized, though there are pitfalls in their use. Finally, one must recognize that individual characteristics may outweigh the ethnic and that a good caring relationship can compensate for many cultural missteps.     

Reinvestigation of the shape and state of hydration of the skeletal myosin subfragment 1 monomer in solution

Hydrodynamic calculations lead to the conclusion that chymotryptic (or ethylenediaminetetraacetic acid) myosin S1 in solution (hydrated), at 1-5 degrees C, can be modeled as a prolate ellipsoid, with an axial ratio lying between p = 1.0 and 2.5 (major axis between 100.5 A, for p = 1.0, and 162.5 A, for p = 2.5). The degree of hydration is considerable (1.24 g/g for p = 2.5 and 2.02 g/g for p = 1.0). The dehydrated myosin head is pear-shaped under the electron microscope, and its narrowest part is located near the junction with the tail [Elliott, A., & Offer, G. (1978) J. Mol. Biol. 123, 505-519]. Mendelson & Kretzschmar [Mendelson, R. A., & Kretzschmar, K.M. (1980) Biochemistry 19, 4103-4108] have shown that the pear-shaped molecule does not predict the experimental X-ray scattering curve. Nor is this model able to predict the hydrodynamic values. The three-dimensional model for S1 used by Mendelson and Kretzschmar gives a rather good fit to the experimental X-ray scattering curve, but it does not predict the hydrodynamic values. In order to try to reconcile the three models and to fit the X-ray scattering curve and the hydrodynamic data, we suggest that, in solution, the S1 monomer has the shape of a prolate ellipsoid and that an inclusion of bound water exists at one extremity of the protein. The rest of bound water surrounds the protein. As first approximation, the dry protein and the hole are assumed to have the same shape as the hydrated molecule (prolate ellipsoid; p).(ABSTRACT TRUNCATED AT 250 WORDS)