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Biomedical subjects

M Potts

Publications and source records attributed to M Potts.

At least 19 recordsLinked to original sources
PubMed1992

Myoglobin in a cyanobacterium.

Myoglobin was found in the nitrogen-fixing cyanobacterium Nostoc commune. This cyanobacterial myoglobin, referred to as cyanoglobin, was shown to be a soluble hemoprotein of 12.5 kilodaltons with an amino acid sequence that is related to that of myoglobins from two lower eukaryotes, the ciliated protozoa Paramecium caudatum and Tetrahymena pyriformis. Cyanoglobin is encoded by the glbN gene, which is positioned between nifU and nifH-two genes essential for nitrogen fixation-in the genome of Nostoc. Cyanoglobin was detected in Nostoc cells only when they were starved for nitrogen and incubated microaerobically.

Amino Acid Sequence↗
PubMed1992

AIDS in Africa.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Gene cluster rpoBC1C2 in cyanobacteria does not constitute an operon.

The core enzyme of the cyanobacterial DNA-dependent RNA polymerase contains a unique component, gamma, which is absent from the corresponding enzymes of other eubacteria. In the heterocystous cyanobacterium Nostoc commune the gene encoding gamma, rpoC1, is immediately adjacent to, and downstream of, rpoB. The rpoC1 gene, and a 3' adjacent gene, rpoC2, correspond to the single rpoC gene found in Escherichia coli with respect to those domains conserved within their translational products. Northern analysis and primer extension assay show that in N. commune, rpoC1 and rpoC2 are transcribed separately from rpoB. The promoter of rpoC1C2 can direct the expression of a promotorless lacZ gene in E. coli. As a consequence, cyanobacterial rpo gene expression is distinct from the mode of cotranscription described for the equivalent sequences found in other eubacteria, archaebacteria, and plant chloroplasts. Also in this paper, a simple protocol for RNA isolation, which should be applicable for RNA isolation from plant cells, is presented.

Base Sequence↗
PubMed1991

Paraguayan pharmacies and the sale of pseudo-abortifacients.

This study was conducted in 1985 in Asunción, Paraguay, 6 years after the closure of the state supported family planning services. Data from national surveys in 1977 and 1987 permit a comparison of sources of contraceptive supplies before and after the elimination of government support for family planning. The purchase of pseudo-abortifacients from private pharmacies was used as an indication of induced abortion. After the loss of government clinics, it is suggested that some women turned to pharmacists to obtain pseudo-abortifacients when faced with unwanted pregnancy. There is an indication of increased pseudo-abortifacient use, particularly among unmarried women and those from poorer neighbourhoods.

Abortifacient Agents↗
PubMed1990

Do the benefits of breastfeeding outweigh the risk of postnatal transmission of HIV via breastmilk?

Conflicting recommendations have been offered about whether HIV+ mothers should breastfeed. Since there is a strong precedent for US infant feeding practices to be imitated in developing countries, a model was constructed to estimate infant mortality if the CDC admonition for HIV+ mothers not to breastfeed were upheld in less developed settings. Estimates are given for infant mortality in the presence and absence of breastfeeding across several baseline levels of infant mortality and across several theoretical rates of transmission through breastfeeding. The infant mortality associated with HIV infection acquired through breastfeeding is estimated to be lower than the mortality associated with the diseases of infancy that would result if breastmilk were withheld. The difference in these estimates is greater in areas with high baseline levels of infant mortality.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Novel water stress protein from a desiccation-tolerant cyanobacterium. Purification and partial characterization.

A desiccation-tolerant cyanobacterium Nostoc commune accumulates a novel group of acidic proteins when colonies are subjected to repeated cycles of drying and rehydration. The proteins occur in high concentrations; they have isoelectric points between 4.3 and 4.8 and apparent molecular masses between 30 and 39 kDa. The purification of three of these proteins with molecular masses of 33, 37, and 39 kDa is described. The amino-terminal sequence of the 39-kDa protein is Ala-Leu-Tyr-Gly-Tyr-Thr-Ile-Gly-Glu. Peptide mapping of the 39- and the 33-kDa proteins, using different protease, gave similar patterns of digestion fragments. The amino acid compositions of the proteins isolated were similar, and each cross-reacted with a polyclonal antibody raised against the largest (39-kDa) protein. The results indicate that the microheterogeneity observed was generated by in vivo proteolysis of the 39-kDa protein. It is suggested that this protein is a water stress protein with a protective function on a structural level.

Amino Acid Sequence↗
PubMed1989

Performance of the copper T-380A intrauterine device in breastfeeding women.

The effect of breastfeeding on performance of the TCu-380A IUD was evaluated using data derived from multicenter clinical trials. Insertion events for breastfeeding women (N = 559) and non-breastfeeding women (N = 590) were compared as well as discontinuations of IUD use through six months following insertion. Results indicate that breastfeeding women inserted with a TCu-380A are more likely than non-breastfeeding women to have a smooth, pain-free insertion, few postinsertion bleeding and pain problems, and a high rate of continuation of IUD use. There were no uterine perforations reported from either group of women.

Adult↗
PubMed1989

The effects of a progestin-only oral contraceptive (levonorgestrel 0.03 mg) on breast-feeding.

This study was a non-randomized clinical trial which compared the breast-feeding experience of 250 Argentine women taking levonorgestrel 0.03 mg daily (begun one week after delivery) with that of 250 women using non-hormonal contraceptives. Weight gain of unsupplemented infants, the most important of the several criteria used to assess breast-feeding performance, was similar for the two contraceptive groups. Levonorgestrel users began supplementary feeding of their infants significantly later than did non-hormonal users; levonorgestrel users were also somewhat less likely to discontinue breast-feeding during the study period. The two contraceptive groups were similar with regard to several other measures of breast-feeding performance: growth of all infants (regardless of supplementation), patterns of contraceptive discontinuation, mothers' subjective impressions of breast-milk sufficiency, and comparison of supplementation initiation with previous experience.

Adult↗
PubMed1989

LHRH agonists and the prevention of breast and ovarian cancer.

Early age at natural menopause or bilateral ovariectomy substantially reduce a woman's lifetime risk of breast cancer. Reversible 'bilateral ovariectomy' can now in effect be achieved by 'high-dose' luteinising hormone releasing hormone (LHRH) agonists (LHRHAs). The harmful effects of such medical reversible bilateral ovariectomy, in particular the increased risks of coronary heart disease and osteoporosis, can in all likelihood be obviated by 'low-dose' oestrogen replacement therapy (ERT), specifically 0.625 mg of conjugated equine oestrogens (CEE) for 21 days in each 28-day treatment cycle, and such ERT use will only negate to a relatively small extent the beneficial effect of such bilateral ovariectomy on breast cancer risk. We calculate that such an LHRHA plus low-dose ERT regimen given to a premenopausal woman for 10 years will, in addition to being a most effective contraceptive, decrease her lifetime risk of breast cancer by more than 50%. We calculate that such a 10-year regimen will also decrease her risk of ovarian cancer by two-thirds. This regimen should leave endometrial cancer risk and bone metabolism unaltered, and may reduce the risk of heart disease. The addition of a 'low-dose' progestogen to the regimen for 12 days in each 28-day treatment cycle would be beneficial to the endometrium, but it will adversely affect risk factors for heart disease and it may significantly reduce the benefit of the regimen as regards breast cancer. A satisfactory compromise may be to add a low-dose progestogen for 12 days at less frequent intervals. Another possibility may be to deliver a progestogen solely to the endometrium with an intra-uterine device; the benefits of such a regimen would be a significant reduction in the incidence of breast, ovarian and endometrial cancer.

Breast Neoplasms↗
PubMed1989

Nostoc commune UTEX 584 gene expressing indole phosphate hydrolase activity in Escherichia coli.

A gene encoding an enzyme capable of hydrolyzing indole phosphate was isolated from a recombinant gene library of Nostoc commune UTEX 584 DNA in lambda gt10. The gene (designated iph) is located on a 2.9-kilobase EcoRI restriction fragment and is present in a single copy in the genome of N. commune UTEX 584. The iph gene was expressed when the purified 2.9-kilobase DNA fragment, free of any vector sequences, was added to a cell-free coupled transcription-translation system. A polypeptide with an Mr of 74,000 was synthesized when the iph gene or different iph-vector DNA templates were expressed in vitro. When carried by different multicopy plasmids and phagemids (pMP005, pBH6, pB8) the cyanobacterial iph gene conferred an Iph+ phenotype upon various strains of Escherichia coli, including a phoA mutant. Hydrolysis of 5-bromo-4-chloro-3-indolyl phosphate was detected in recombinant E. coli strains grown in phosphate-rich medium, and the activity persisted in assay buffers that contained phosphate. In contrast, indole phosphate hydrolase activity only developed in cells of N. commune UTEX 584, when they were partially depleted of phosphorus, and the activity associated with these cells was suppressed partially by the addition of phosphate to assay buffers. Indole phosphate hydrolase activity was detected in periplasmic extracts from E. coli (Iph+) transformants.

Cyanobacteria↗