Prevalence of modifiable risk factors for sudden infant death syndrome in British Forces Germany

A questionnaire survey was conducted amongst parents in the military community in British Forces Germany to investigate the prevalence of known and suspected risk factors for Sudden Infant Death Syndrome. Over a thousand questionnaires were returned (response rate 58%) and these showed that the prevalence of babies being placed in the prone position to sleep is now extremely low and the use of room thermometers to help control ambient temperature is widespread. However 29% of the mothers had smoked in pregnancy and 44% of households with a new-born baby had at least one parent who smoked. Additional health promotion activity aimed at reducing the prevalence of smoking in pregnancy and amongst the parents of new-born babies is recommended.

The interaction of a Huntington disease factor with receptors for the neurotoxin kainic acid

A factor from mammalian and human brain, which inhibits the rate of migration of leukocytes obtained from sufferers from Huntington disease (Walls and Ruwoldt, 1984), inhibited the specific binding of the neurotoxin [3H]kainic acid to rat brain synaptic membranes. The factor was present in sucrose-particulate but not in soluble fractions from rat sub-cortical tissue, and was destroyed by tryptic digestion. Whereas an ammonium sulfate fraction of direct saline extracts of brain (Walls and Ruwoldt, 1984) gave poor chromatography on HPLC, prior separation of a sucrose-particulate fraction resulted in much improved chromatography. There was a good concordance between leukocyte migration inhibitory activity and [3H]kainic acid binding inhibitory activity. The factor may be an endogenous modulator of the kainic acid subset of receptors for the excitatory neurotransmitter glutamic acid.

Uptake of gamma-aminobutyric acid and L-glutamic acid by synaptosomes from postmortem human cerebral cortex: multiple sites, sodium dependence and effect of tissue preparation

The uptake of gamma-aminobutyric acid (GABA) and L-glutamic acid by synaptosomes prepared from frozen postmortem human brain was shown to be effected via distinct high and low affinity sites. At approximately 17 h postmortem delay, the kinetic parameters for GABA uptake were: high affinity site, Km 7.1 +/- 2.5 microM, Vmax 18.7 +/- 4.8 nmol.min-1 per 100 mg protein; low affinity site, Km 2 +/- 1 mM, Vmax 425 +/- 250 nmol.min-1 per 100 mg protein (means +/- S.E.M., n = 13). Kinetic parameters for L-glutamate uptake were: high affinity site, Km 7.5 +/- 1.0 microM, Vmax 85 +/- 8 nmol.min-1 per 100 mg protein; low affinity site, Km 1.8 +/- 1.2 mM. Vmax 780 +/- 175 nmol.min-1 per 100 mg protein (n = 11). A detailed kinetic analysis of high affinity GABA uptake was performed over a range of sodium ion concentrations. The results were consistent with a coupling ratio of one Na+ ion to one GABA molecule; a similar result was found with rat brain synaptosomes. However, rat and human synaptosomes differed in the degree to which the substrate affinity of the high affinity GABA uptake site varied with decreasing Na+ ion concentration. High affinity GABA uptake was markedly affected by the method used to freeze and divide the tissue, but did not vary greatly in different cortical regions. There was some decline of high affinity GABA uptake activity with postmortem delay, apparently due to a loss of sites rather than a change in site affinity.

The apical and basal plasma membranes of the human placental syncytiotrophoblast contain different erythrocyte membrane protein isoforms. Evidence for placental forms of band 3 and spectrin

Using immunochemical techniques, we identified forms of erythrocyte membrane proteins in apical and basal plasma membranes of human placental trophoblast. A wheat germ agglutinin-binding intrinsic protein was present in the microvillous (maternal facing) but not the basal (fetal facing) membrane of the syncytiotrophoblast epithelium. Conversely, erythrocyte-related proteins of the basal membrane included two intrinsic membrane proteins, a 95,000 Mr band 3 isoform and a form of spectrin. These four proteins were all absent from the microvillous membrane. The basal membrane spectrin isoform was also present in basal membrane skeletons. A 70,000 Mr polypeptide which reacted with antibodies to band 3 was present in both microvillous and basal plasma membranes. Therefore, certain isoforms of red cell membrane proteins are polarized between the two surfaces of the human placental syncytiotrophoblast. We propose that the localization of spectrin to the basal membrane is related to the less bundled organization of microfilaments at this membrane compared with that of the microvillous membrane. The band 3 isoforms are candidates for participation in maternofetal anion transport.

Substituent effects on the redox reactions of tetraphenylporphyrins

The effect of substituents on pi radical reactions of para-substituted tetraphenylporphyrins was investigated by cyclic voltammetry in methylene chloride. In all cases electron donating substituents produced a more difficult reduction and an easier oxidation. Plots of E1/2 vs. a yielded Hammett linear free energy relationships for cation radical and dication formation and anion radical and dianion formation. An average reaction constant of p=0.07+/-0.01 V was obtained. This was true for tetraphenylporphyrins containing the central metals VO, Mn, Fe, Co, Ni, Cu, and Zn, as well as the free base H2 (p-X)TPP. The value of p appears not to be directly affected by the central metal oxidation state or the overall charge on the complex.

Characterization of the binding of 125-I-labeled epidermal growth factor to human fibroblasts

Epidermal growth factor (EGF) was labeled with 125-I by a lactoperoxidase technique. The unlabeled, monoiodinated and diiodinated species were separated by DEAE-cellulose chromatography and found to possess equivalent biological activities. The binding of monoiodinated epidermal growth factor to human fibroblasts was specific in that unrelated polypeptides did not affect the binding reaction. The binding reaction was a saturable process and was time- and temperature-dependent. A Scatchard analysis of the binding data indicated that each cell was capable of binding approximately 100, 000 molecules of 125-I-EGF. The apparent dissociation constant for the binding reaction was calculated to be 2.7 to 4.3 times 10-minus 10 M. Subsequent to the binding of 125-I-EGF to the fibroblasts, the growth factor was degraded by a cell-mediated proteolysis and [125-I]monoiodotyrosine appeared in the medium. The extent of degradation was reduced by the protease inhibitors, tosyl-L-lysine chloromethyl ketone and the benzyl ester of guanidobenzoic acid. Active binding sites of 125-I-egf appeared to be present in some but not all cell types. These results demonstrated that cells derived from a number of species (human, mouse, rat, and chick) possessed receptors that interacted with this mouse-derived growth factor.