Requirement of the hinge domain for dimerization of Ca2+-ATPase large cytoplasmic portion expressed in bacteria.

The large cytoplasmic domain of rabbit sarcoplasmic reticulum Ca2+-ATPase was overexpressed in Escherichia coli as a 48 kDa fusion protein, designated p48, containing an N-terminal hexa-His tag. Purification conditions were optimized, thus conferring long-term stability to p48. Circular dichroism spectroscopy and the pattern of limited trypsinolysis confirmed the proper folding of the domain. p48 retained 0.5 +/- 0.1 mol of high affinity 2',3'-O-(2,4,6-trinitrophenyl)adenosine-5'-triphosphate (TNP-ATP) binding sites per mol of polypeptide chain with an apparent dissociation constant of about 8 microM. Size-exclusion FPLC using protein concentrations in the range 0.03 5 mg/ml showed that p48 was essentially monodisperse with apparent molecular mass and Stokes radius (Rs) values compatible with a dimer (100 kDa and 40 A, respectively). Analysis of p48 by small-angle X-ray scattering provided an independent second proof for a dimeric p48 particle with a radius of gyration (Rg) of 39 A, suggesting that the dimer was not spherical (Rs/Rg = 1.026). When digested by proteinase K, p48 was converted to a 30 kDa fragment, designated p30, which was very resistant to further proteolysis. p30 retained high affinity TNP-ATP binding (Kd = 8 microM) and eluted as a monomer (35 kDa) in size-exclusion FPLC. As opposed to p48, the p30 fragment did not react with monoclonal antibody A52 [Clarke et al., J. Biol. Chem. 264 (1989) 11246-11251] which recognizes region E657-R672 located upstream of the hinge domain of the Ca2+-ATPase. These results indicate a requirement of the hinge domain (670-728) region for self-association of the p48 large hydrophilic domain as a dimer. We propose that this behavior points to a possible role of the hinge domain in dimerization of sarcoplasmic reticulum Ca2+-ATPase in the native membrane.

[The determination of the normal values of blood flow velocities in the superior mesenteric artery of premature and term newborns with duplex sonography]. / Normalwerterstellung von Blutströmungsgeschwindigkeiten an der Arteria mesenterica superior bei Früh- und Reifgeborenen mit der Duplexsonographie.

In a prospective study blood flow velocity measurements were performed in 110 "healthy" newborn with duplex Doppler sonography in the superior mesenteric artery to obtain standard values. In 49 of these neonates 15, 30, and 45 minutes following feeding examinations were performed. Peak systolic flow velocity, end systolic flow velocity, time average flow velocity and time average maximum flow velocity were determined, the resistance and Pourcelot index as well as the volume blood flow were calculated. The children's gestational age was 27-42 weeks, the postnatal age was 2-68 days and the body weight was 920-4190 g. All measured blood flow velocities showed a synchronous relation to feeding with an increase of blood flow velocity between 15 and 30 minutes and a decrease of blood flow velocity after feeding. The ascertained fasting measurements from 91 newborn (last feeding > 3 h < 12 h) differed significantly from the ascertained basic fasting measurements (last feeding > 12 h) from 15 infants.

Placebo-controlled efficacy study of hepatitis A vaccine in Valdivia, Chile.

A placebo-controlled, double-blind study on the efficacy of a hepatitis A vaccine (SmithKline Beecham Biologicals) was started in a region of Chile in September 1990, using hepatitis B vaccine as control. A total of 260 healthy children, 6-15 years of age, negative for antibody to hepatitis A virus (anti-HAV), antibody to HAV immunoglobulin M (IgM), hepatitis B surface antigen, and antibody to hepatitis B surface and core antigens by ELISA tests within 7 days before vaccination, were randomly assigned to two study groups: 128 children received the vaccine with a yellow label (group 1), and 132 children the vaccine with an orange label (group 2) at months 0, 1 and 6. Blood for serology and transaminase determination was drawn at months 1, 2, 6, 7 and 12. Both vaccines were tolerated equally well and no serious side effects were seen. In group 1 (presumed hepatitis A vaccine group), anti-HAV was detected (20% inhibition was used as the cut-off level) in 122 of 128 children (95.5%) tested at month 1, in 126 of 127 (99.2%) at month 2, in 126 of 127 (99.2%) at month 6 and in 126 of 126 (100%) at month 7. One anti-HAV seroconversion seen at month 1 was associated with presence of anti-HAV IgM and therefore probably represents HAV infection. Geometric mean anti-HAV concentration of the other children was 128, 342, 214 and 2301 mIU/ml at months 1, 2, 6 and 7, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

[Different composition of the cell wall polysaccharides in Saccharomyces cerevisiae S288 and in an osmosis sensitive mutant]. / Unterschiedliche Zusammensetzung der Zellwand-Polysaccharide beiSaccharomyces cerevisiae S288 und einer osmolabilen Mutante.

Determination of the polysaccharide contents and structural studies on the mannan by acetolysis and permethylation analysis shows an altered polysaccharide biosynthesis of the osmotic-sensitive mutant VY 1160 of Saccharomyces cerevisiae S 288. The mutant contains more glucan, less mannan, and less alkali-soluble glycogen. Its mannan is characterized by more short side chains and less long side chains. Its main chain is 1 leads to 6-linked, but its side chains consist of more 1 leads to 3- than 1 leads to 2-linked mannose units.