Putative role of a 70 kDa outer-surface protein in promoting cell-surface hydrophobicity of Serratia marcescens RZ

Serratia marcescens RZ has been previously shown to possess pronounced cell-surface hydrophobicity, as evidenced by its affinity for hydrocarbons and polystyrene. The present report suggests the involvement of a 70 kDa protein, serraphobin, in this phenomenon. The 70 kDa protein was recovered from both the cell surface and culture supernatant of hydrophobic wild-type cells, but was either totally absent or present in minor quantities in hydrophobicity-deficient mutants. Similarly, loss of hydrophobicity of RZ cells following growth at 39 degrees C was accompanied by loss of the protein. Serraphobin was capable of binding to hexadecane droplets following a brief mixing procedure, and could be desorbed by solidifying and melting the hexadecane phase.     

Age at first coitus and choice of contraceptive method: preliminary report on a study of factors related to cervical neoplasia.

The incidence of cancer of the uterine cervix appears to be species-specific, thus confounding extrapolation of results from studies with experimental animals. In humans, the incidence varies more by social groups than does any other primary cancer. In a recent study, Puerto Ricans were found to have a 25 times higher risk of cervical cancer than Jews. Blacks had 4 times the risk of non-Jewish Caucasians. Age at 1st coitus (AFC) and number of coital partners have been related to increased risks. Upper socioeconomic level women have had contraceptive pills prescribed more often than others. Initial interviews and recordings of gynecologic results have been completed by the Institute for Survey Research for 25,000 American women attending large clinics and group health centers in 9 continental cities and 3 cities in Puerto Rico. Data concerning contraceptive, sexual, and reproductive history have been completed for almost 12,000. Years of education and current age have had a significant effect (p less than .001) on AFC. Gravida was also significantly related to AFC (p less than .001). The AFC of North American blacks was lower than others. Women who chose to use the pill were found to have a higher prevalence of cytologic dysplasia at the time of choice than other women. Data provide no evidence to suggest that the widespread use of oral contraceptives since the mid-1960s has been followed by increasing rates of carcinoma in situ. Other epidemiological research has failed to reveal retrospective associations between oral contraceptive use and abnormal cervical cytology. Present results are consistent with this pattern.     

The Ca2+-Na+ antiporter of heart mitochondria operates electroneutrally

The transmembrane potential of heart mitochondria during Na⁺-induced Ca²⁺ release has been monitored continuously with a Tetraphenylphosphonium-sensitive electrode. The data obtained indicate that the exchange process does not generate an electrical current, and provides direct support for the concept of a 2 Na⁺ per 1 Ca²⁺ exchange.     

Effect of the Thiol-Oxidizing Agent Diamide on the Growth of Escherichia coli

Oxidation of glutathione within Escherichia coli cells by diamide, (CH(3))(2)NCON=NCON(CH(3))(2), stops growth but does not cause cell death. Normal growth rates are resumed after periods which vary in length according to the diamide concentration. Consumption of excess reagent with added glutathione quickly reverses the inhibition. Another thiol-oxidizing agent, azoester, C(6)H(5)N=NCOOCH(3), causes lysis.