Passive exposure to tobacco smoke: saliva cotinine concentrations in a representative population sample of non-smoking schoolchildren.

Saliva cotinine concentrations in 569 non-smoking schoolchildren were strongly related to the smoking habits of their parents. When neither parent smoked the mean concentration was 0.44 ng/ml, rising to 3.38 ng/ml when both parents were cigarette smokers. Mothers'' smoking had a stronger influence than did fathers'' (p less than 0.01). In addition, there was a small independent effect of number of siblings who smoked (p less than 0.01). The dose of nicotine received from fathers'' smoking was estimated as equivalent to the active smoking of 30 cigarettes a year, that from mothers'' smoking as equivalent to smoking 50 cigarettes a year, and that from both parents smoking as equivalent to smoking 80 cigarettes a year. This unsolicited burden may be prolonged throughout childhood and poses a definite risk to health.     

Amplification of sodium- and potassium-activated adenosinetriphosphatase in HeLa cells by ouabain step selection

A multistep selection for ouabain resistance was used to isolate a clone of HeLa S3 cells that overproduces the plasma membrane sodium, potassium activated adenosinetriphosphatase (Na+,K+-ATPase). Measurements of specific [3H]ouabain-binding to the resistant clone, C+, and parental HeLa cells indicated that C+ cells contain 8-10 X 10(6) ouabain binding sites per cell compared with 8 X 10(5) per HeLa cell. Plasma membranes isolated from C+ cells by a vesiculation procedure and analyzed for ouabain-dependent incorporation of [32P]phosphate into a 100,000-mol-wt peptide demonstrated a ten- to twelvefold increase in Na+,K+-ATPase catalytic subunit. The affinity of the enzyme for ouabain on the C+ cells was reduced and the time for half maximal ouabain binding was increased compared with the values for the parental cells. The population doubling time for cultures of C+ cells grown in dishes was increased and C+ cells were unable to grow in suspension. Growth of C+ cells in ouabain-free medium resulted in revertant cells, C-, with biochemical and growth properties identical with HeLa. Karyotype analysis revealed that the ouabain-resistant phenotype of the C+ cells was associated with the presence of minute chromosomes which are absent in HeLa and C- cells. This suggests that a gene amplification event is responsible for the Na+,K+-ATPase increase in C+ cells.     

Epitopes on foot-and-mouth disease virus outer capsid protein VP1 involved in neutralization and cell attachment.

Foot-and-mouth disease virus structural protein VP1 elicits neutralizing and protective antibody and is probably the viral attachment protein which interacts with cellular receptor sites on cultured cells. To study the relationships between epitopes on the molecule related to neutralization and cell attachment, we tested monoclonal antibodies prepared against type A12 virus, isolated A12 VP1, and a CNBr-generated A12 VP1 fragment for neutralization and effect on viral absorption. The antibodies selected for analysis neutralized viral infectivity with varying efficiencies. One group of antibodies caused a high degree of viral aggregation and inhibited the adsorption of virus to cells by 50 to 70%. A second group of antibodies caused little or no viral aggregation but inhibited the adsorption of virus to cells by 80 to 90%. One antibody, which is specific for the intact virion, caused little viral aggregation and had no effect on the binding of virus to specific cellular receptor sites. Thus, at least three antigenic areas on the surface of foot-and-mouth disease virus which were involved in neutralization were demonstrated. One of the antigenic sites appears to have been responsible for interaction with the cellular receptor sites on the surface of susceptible cells.     

Identification of the DNA sequences encoding the large subunit of the mRNA-capping enzyme of vaccinia virus.

The DNA sequences encoding the large subunit of the mRNA-capping enzyme of vaccinia virus were located on the viral genome. The formation of an enzyme-guanylate covalent intermediate labeled with [alpha-32P]GTP allowed the identification of the large subunit of the capping enzyme and was used to monitor the appearance of the enzyme during the infectious cycle. This assay confirmed that after vaccinia infection, a novel 84,000-molecular-weight polypeptide corresponding to the large subunit was rapidly synthesized before viral DNA replication. Hybrid-selected cell-free translation of early viral mRNA established that vaccinia virus encoded a polypeptide identical in molecular weight with the 32P-labeled 84,000-molecular-weight polypeptide found in vaccinia virions. Like the authentic capping enzyme, this virus-encoded cell-free translation product bound specifically to DNA-cellulose. A comparison of the partial proteolytic digestion fragments generated by V8 protease, chymotrypsin, and trypsin demonstrated that the 32P-labeled large subunit and the [35S]methionine-labeled cell-free translation product were identical. The mRNA encoding the large subunit of the capping enzyme was located 3.1 kilobase pairs to the left of the HindIII D restriction fragment of the vaccinia genome. Furthermore, the mRNA was determined to be 3.0 kilobases in size, and its 5' and 3' termini were precisely located by S1 nuclease analysis.     

Intracellular Ca and cell injury: A paradoxical role of Ca in complement membrane attack

Disturbances in intracellular Ca2+ are known to be important in cell injury caused by a wide range of toxic factors. The complement system is a major effector of immune damage in vivo, and is known to be involved in the pathogenesis of many immune diseases. We present here evidence that the potentially lethal membrane attack complex of complement causes a rapid increase in intracellular free Ca2+ concentration before any other detectable biochemical changes in the cell. In nucleated cells the increased intracellular free Ca2+ concentration initially stimulates recovery processes, allowing the cell to escape mild complement attack and also activates the production of inflammatory mediators, which may amplify an ongoing inflammatory response. More severe complement membrane attack causes a more rapid rise in intracellular free Ca2+ concentration allowing a threshold to be breached above which recovery processes are overwhelmed, and cell death occurs. The importance of non-lytic effects and recovery processes mediated by Ca2+, and the molecular basis of these effects are discussed, and the hypothesis proposed that the cell-injuring effects of other "pore-forming" toxins are also caused by increases in intracellular free Ca2+.     

Analysis of fluorescence transients of DCMU-treated leaves of Triticum species to provide estimates of the densities of photosystem II reaction centres

The fluorescence of the chlorophyll associated with photosystem II was studied in seedling and flag leaves of Triticum species. Seedling leaves of the diploid species T. urartu had higher values of t (the normalised area over the fluorescence induction curve of DCMU treated leaves) than those of the other species studied which included hexaploid T. aestivum. However this difference was not evident when leaves were grown in a low light intensity (40 µmol quanta of photosynthetically active radiation m^–2 s^–1). The smaller total number of chlorophyll molecules per photosystem II reaction centre (chl/RCII) in T. urartu (177) as compared with the other species (mean 234) was deduced from the observed differences in t. As a consequence of its lower chl/RCII, despite slightly lower chlorophyll content (mg m^–2), T. urartu had a greater density of reaction centres than the other species (2880 cf 2230 nmol m^–2 of leaf). Consistent with the lower chl/RCII of T. urartu, it had a higher chlorophyll a/b ratio than the other genotypes. Seedling leaves of T. urartu had higher light saturated rates of photosynthesis than those of the other species, when grown at high light, a difference associated with reaction centre density.In flag leaves, when the complications due to variable development and senescence patterns were eliminated, t of the diploid species including T. urartu was lower than that of T. aestivum. The lower apparent chl/RCII of T. urartu arose partly because the molar extinction coefficient of the chlorophyll in the leaves of T. urartu was greater than in T. aestivum. However, the density of PS II reaction centres was slightly lower for the diploid species studied because their chlorophyll contents were lower than the hexaploids.The validity of the method for estimating chl/RCII from fluorescence transients is discussed. The possibility is considered that the difference in apparent chl/RCII of flag and seedling leaves of R. urartu as compared to the other five genotypes is a consequence of its different adaptive response to the spectral quality of the light.     

Chromatographic resolution of chicken phosvitin. Multiple macromolecular species in a classic vitellogenin-derived phosphoprotein.

The 622-residue amino acid sequence of the hydrophilic domain in the porcine NADPH-cytochrome P-450 reductase (EC 1.6.2.4) is reported. The structural data required to complete the sequences published previously [Vogel, Kaiser, Witt & Lumper (1985) Biol. Chem. Hoppe-Seyler 366, 577-587] and to establish the primary structure of the porcine hydrophilic domain have been obtained by sequencing proteolytic subfragments derived from CNBr fragments and by characterizing the overlapping S-[14C]methylmethionine-containing peptides isolated from tryptic digests of the [14C]methyl-labelled hydrophilic domain. The hydrophilic domain displays 91.8% positional identity with that of the corresponding domain in the rat NADPH-cytochrome P-450 reductase. The region Val528-Ser678 in the NADPH-cytochrome P-450 reductase shows a significant homology to the sequence Ile165-Tyr314 in the spinach ferredoxin-NADP+ oxidoreductase. A model for the secondary structure of the hydrophilic domain has been derived by computer-assisted analysis of the amino acid sequence. Cys472 and Cys566 are protected against chemical modification in the NADP+ complex of the NADPH-cytochrome P-450 reductase.     

Spectinomycin resistance due to a mutation in an rRNA operon of Escherichia coli

A spectinomycin resistance mutation was isolated in an Escherichia coli rRNA operon (rrnH) located on a multicopy plasmid. Cell-free protein-synthesizing extracts made from cells containing the plasmid were partially resistant to spectinomycin. Although spectinomycin is an aminoglycoside antibiotic, the mutation did not confer resistance to any other aminoglycoside antibiotic tested.