Australia Antigen and Liver Function Tests Following Infectious Hepatitis—A Study of 111 Patients in Quest of Aids in Blood Donor Screening

An epidemic of infectious hepatitis involving 99 patients and employees of a state mental hospital revealed Australia antigen Au(1) to be absent from the blood of all but one of the subjects when tested at six weeks, three months, nine months and 12 to 18 months after onset of jaundice. The single patient with Au(1) at 12 months had no enzyme abnormality to indicate residual liver disease.If Au(1) is the virus of hepatitis these data would support the concept that persistent or long standing viremia is not a feature of epidemic hepatitis. Moreover, results of this study suggest that the Au(1) test should not be used to establish the absence of a past history of hepatitis in blood donors. These data do not establish the value of the Au(1) test in blood donors with active viremia, but do suggest that of 111 patients with recent hepatitis 1 percent had persistent antigenemia and 4 percent probably had circulating antigen antibody complexes and constituted a potential risk to recipients of their blood. The degree of risk to recipients from transfused blood of post-hepatitis patients without demonstrable Au(1) cannot be assessed.     

Inhibition of Transformation of Bacillus subtilis by Heavy Metals

Mercuric ions, as well as organomercuric ions and cadmium ions, can inhibit deoxyribonucleic acid-mediated transformation in Bacillus subtilis 168 without decreasing the viability of the total population. Differences in the inhibition of transformation by mercuric ions are identifiable on a temporal and concentration dependence basis. Sensitivity to low concentrations (9.2 x 10(-8) M) appears early in the uptake of deoxyribonucleic acid before the transformed markers have become insensitive to deoxyribonuclease. Resistance to "low concentrations" of Hg(2+) is kinetically indistinguishable from the requirement for magnesium in the transformation process. This inactivation is not reversed by the mercury-binding compound glutathione. Sensitivity to mercuric ions at a higher concentration (5.52 x 10(-7) M) occurs after the donor deoxyribonucleic acid has become insensitive to deoxyribonuclease. These complex interactions between mercuric ions and the process of transformation are discussed.     

Biogenesis of mitochondria. Phospholipid synthesis in vitro by yeast mitochondrial and microsomal fractions

The ability in vitro of yeast mitochondrial and microsomal fractions to synthesize lipid de novo was measured. The major phospholipids synthesized from sn-[2-(3)H]glycerol 3-phosphate by the two microsomal fractions were phosphatidylserine, phosphatidylinositol and phosphatidic acid. The mitochondrial fraction, which had a higher specific activity for total glycerolipid synthesis, synthesized phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine and phosphatidic acid, together with smaller amounts of neutral lipids and diphosphatidylglycerol. Phosphatidylcholine synthesis from both S-adenosyl[Me-(14)C]methionine and CDP-[Me-(14)C]choline appeared to be localized in the microsomal fraction.     

A dihedral angle-vicinal proton coupling constant correlation for the α–β bond of amino acid residues

A coupling constant-dihedral angle correlation for the H? Cα? Cβ? H system of amino acid residues in peptides has been derived from a set of model compounds covering the full range of dihedral angles. The expression obtained, J = 11.0 cos₂ θ ?1.4 cos θ + 1.6 sin₂θ, is close to those already used in pmr studies of peptide conformation, and provides a firmer foundation for them. A factor limiting the precision of this and other “Karplus relations” is illustrated.     

An Improved Diluent for Rubella Hemagglutination and Hemagglutination-Inhibition Tests

Rubella hemagglutinating (HA) antigen was prepared in BHK-21 tissue as 5% cell suspensions and from unconcentrated and 20× concentrated infected supernatant fluids. In some instances, unconcentrated fluids were treated with Tween 80 and ether; cell suspensions were treated with ether alone. Preparations were tested for HA activity in dextrose-gelatin-Veronal (DGV) buffer solutions; 0.85% NaCl; Sorenson's phosphate-buffered saline, pH 7.2; and a diluent of 0.9% NaCl, 0.1% CaCl₂ (anhydrous), and 0.1% MgSO₄·7H₂O. HA titers were consistently two- to fourfold higher in the saline with added Ca⁺⁺ and Mg⁺⁺ than in DGV. Hemagglutination-inhibition titers of paired human sera were the same in either diluent. It is suggested that the interaction between rubella HA antigen and the red cells of young (less than 1-day-old) chicks may be at least partially ion dependent and that titers are enhanced by increased quantities of divalent cations.     

Development of the pulmonary vasculature in newborn lambs: structure-function relationships

Our objectives were 1) to describe the quantitative light microscopy and ultrastructure of newborn lamb lungs and 2) to correlate hemodynamic changes during normoxia and hypoxia with the morphology. By light microscopy, we measured the percent muscle thickness (%MT) and peripheral muscularization of pulmonary arteries and veins from 25 lambs aged less than 24 h, 2-4 days, 2 wk, and 1 mo. At the same ages, lungs were isolated and perfused in situ and, after cyclooxygenase blockade with indomethacin, total, arterial (delta Pa), middle (delta Pm), and venous pressure gradients at inspired O2 fractions of 0.28 (mild hyperoxia) and 0.04 (hypoxia) were determined with inflow-outflow occlusion. During mild hyperoxia, delta Pa and delta Pm fell significantly between 2-4 days and 2 wk, whereas during hypoxia, only delta Pm fell. The %MT of all arteries (less than 50 to greater than 1,000 microns diam) decreased, and peripheral muscularization of less than 100-microns-diam arteries fell between less than 4 days and greater than 2 wk. Our data suggest that 1) the %MT of arteries determines normoxic pulmonary vascular resistance, because only arterial and middle segment resistance fell, 2) peripheral muscularization is a major determinant of hypoxic pulmonary vasoconstriction, because we observed a fall with age in peripheral muscularization of less than 100-micron-diam arteries and in delta Pm with hypoxia, and 3) the arterial limit of the middle segment defined by inflow-outflow occlusion lies in 100- to 1,000-microns-diam arteries.     

Pyrimidine biosynthetic pathway of Pseudomonas fluorescens

Pyrimidine biosynthesis in Pseudomonas fluorescens strain A126 was investigated. In this study, de novo pyrimidine biosynthetic pathway mutant strains were isolated using both conventional mutagenesis and transposon mutagenesis. The resulting mutant strains were deficient for either aspartate transcarbamoylase, dihydroorotase or orotate phosphoribosyltransferase activity. Uracil, uridine or cytosine could support the growth of every mutant strain selected. In addition, the aspartate transcarbamoylase mutant strains could utilize orotic acid to sustain their growth while the orotidine-5'-monophosphate decarboxylase mutant strains grew slowly upon uridine 5'-monophosphate. The wild-type strain and the mutant strains were used to study possible regulation of de novo pyrimidine biosynthesis in P. fluorescens. Dihydroorotase specific activity more than doubled after the wild-type cells were grown in orotic acid relative to unsupplemented minimal-medium-grown cells. Starving the mutant strains of pyrimidines also influenced the levels of several de novo pyrimidine biosynthetic pathway enzyme activities.     

Characterization of a Nerve Growth Factor-Stimulated Protein Kinase in PC12 Cells Which Phosphorylates Microtubule-Associated Protein 2 and pp250

Treatment of PC12 cells with nerve growth factor (NGF) resulted in the rapid, but transient, activation of a protein kinase which specifically phosphorylated an endogenous 250-kDa cytoskeletal protein (pp250). We report that the microtubule-associated protein, MAP2, is an alternative substrate for the NGF-activated kinase. NGF treatment maximally activated the kinase within 5 min; however, the activity declined with longer exposure to NGF. The enzyme was localized predominantly in microsomal and soluble fractions and phosphorylated MAP2 on serine and threonine residues. The soluble enzyme was fractionated by DEAE chromatography and gel filtration and had an apparent Mr of 45,000. The enzyme was purified to near homogeneity by chromatofocussing and had a pI of 4.9. Kinetic analysis revealed that NGF treatment caused a sevenfold increase in Vmax for MAP2. The Km with respect to the MAP2 substrate was approximately 50 nM and was not altered by NGF treatment. A novel feature of the NGF-stimulated enzyme was its sharp dependence on Mn2+ concentration. The active enzyme is likely to be phosphorylated, because inclusion of phosphatase inhibitors was required for recovery of optimal activity and the activity was lost on treatment of the enzyme with alkaline phosphatase. Histones, tubulin, casein, bovine serum albumin, and the ribosomal subunit protein S-6 were not phosphorylated by this enzyme. The NGF-stimulated kinase was distinct from A kinase, C kinase, or other NGF-stimulated kinases. The rapid and transient activation of the protein kinase upon NGF treatment suggests that the enzyme may play a role in signal transduction in PC12 cells.