Enhanced polypeptide synthesis programmed by linear DNA fragments in cell-free extracts lacking exonuclease V

Preparation of an in vitro coupled transcription-translation system from E. coli strains lacking exonuclease V has greatly improved the system for use with added linear DNA fragments. In fact, in extracts of these mutants linear fragments are stable for several hours. However the cell extracts show a high level of endogenous background. To avoid this complication extracts were prepared at 30 degrees C from a mutant carrying a temperature-sensitive exonuclease V. Polypeptides coded by a specific DNA region, e.g., delineated by restriction endonuclease sites, can now be easily identified.

Social support networks of the elderly: racial differences and health care implications

Interest in social support networks has increased in recent years. A configuration of family, friendships, neighbors, neighborhood groups, comprise the social support network of individuals and families. Other entities referred to in social network of individuals and families. Other entities referred to in social support literature include self-help and mutual help organizations. Interest in descriptive studies of social support networks includes both structural and interactional factors. In analyses of structural factors in social support networks, the focus is most frequently on size (number of persons), density (proportion of linkages) and centrality (extent of accessibility).

Binding of 1-nitro[14C]pyrene to DNA and protein in cultured lung macrophages and respiratory tissues

Binding of 1-nitro[14C]pyrene (1-NP) or its metabolites to cellular DNA and protein in cultures of rabbit alveolar macrophages and lung and tracheal tissues was examined. DNA binding was highest in tracheal tissue (136.9 +/- 18.3 pmol 1-NP/mg DNA). DNA binding in macrophages and lung tissue was one-fifth of the level observed in tracheal tissue. Also, 1-NP was bound to cellular protein in tracheal and lung tissues, and at a lower level in macrophages. Co-cultivation of the macrophages with lung and tracheal tissues decreased the DNA binding in tracheal tissue and increased the protein binding in macrophages. This study shows that lung cells and tissue are capable of binding 1-NP or its metabolites to DNA and protein.

A product report: Osto-Zyme as an odor eliminator

A product, Osto-Zyme, was clinically tested at our Institute for the elimination of odor. Thirteen clients were chosen by enterostomal therapists to be tested. The product was sprayed directly into pouch, peristomal skin, and into night drainage units. This product proved very effective in the elimination of odor. The manufacturer of Osto-Zyme is the Richard C. Shelton Co., Wright Brothers Branch, Dayton, Ohio.

Insertion of a MalE beta-galactosidase fusion protein into the envelope of Escherichia coli disrupts biogenesis of outer membrane proteins and processing of inner membrane proteins

The synthesis of a membrane-bound MalE beta-galactosidase hybrid protein, when induced by growth of Escherichia coli on maltose, leads to inhibition of cell division and eventually a reduced rate of mass increase. In addition, the relative rate of synthesis of outer membrane proteins, but not that of inner membrane proteins, was reduced by about 50%. Kinetic experiments demonstrated that this reduction coincided with the period of maximum synthesis of the hybrid protein (and another maltose-inducible protein, LamB). The accumulation of this abnormal protein in the envelope therefore appeared specifically to inhibit the synthesis, the assembly of outer membrane proteins, or both, indicating that the hybrid protein blocks some export site or causes the sequestration of some limiting factor(s) involved in the export process. Since the MalE protein is normally located in the periplasm, the results also suggest that the synthesis of periplasmic and outer membrane proteins may involve some steps in common. The reduced rate of synthesis of outer membrane proteins was also accompanied by the accumulation in the envelope of at least one outer membrane protein and at least two inner membrane proteins as higher-molecular-weight forms, indicating that processing (removal of the N-terminal signal sequence) was also disrupted by the presence of the hybrid protein. These results may indicate that the assembly of these membrane proteins is blocked at a relatively late step rather than at the level of primary recognition of some site by the signal sequence. In addition, the results suggest that some step common to the biogenesis of quite different kinds of envelope protein is blocked by the presence of the hybrid protein.

Response of unmarried adolescents to contraceptive advice and service in Nigeria

The responses of a group of all unmarried, sexually active teenagers in a developing country to offers of contraceptive service were assessed in a prospective, 30-month study at a teaching hospital family planning center. Teenagers of this group constituted 7.2% of the clinic population. The default rate was very high (43.0%) and was most noticeable among users of oral contraceptives. The intrauterine device seemed more acceptable, as were injections of norethisterone enanthate. Possible reasons for this pattern of response are given, and the authors suggest giving new consideration to making the intrauterine device more suitable for and acceptable to teenagers of developing countries. The place of norethisterone enanthate in teenage contraception is also discussed.

Epithienamycins-novel beta-lactams related to thienamycin. I. Production and antibacterial activity

The epithienamycins are cell wall active antibiotics structurally related to N-acetylthienamycin. We have found forty-three isolated of Streptomyces flavogriseus which are capable of producing members of the epithienamycin family. Six major epithienamycin components, and xanthomycin, have been isolated from fermentation broth. Fermentation conditions can be varied to enrich for certain members of the epithienamycin family. All six components show activity in vitro versus a broad spectrum of bacterial species. The weight potencies vary 27 fold from the most active to least active.

Cost effectiveness analysis: some problems of implementation

Cost benefit analyses in the health sector frequently deal with situations in which the money value of the benefits is either difficult or impossible to measure. This paper asserts that the use of cost effectiveness analysis as a means of escaping the need to place a dollar value on benefits does not escape the need for appropriately discounting these benefits when they accrue in different periods over time. The choice of an appropriate discount rate is discussed, and the benefits of elective hysterectomy are used to demonstrate that a serious bias can result from ignoring the need for discounting.