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This study characterised the contribution of a novel ribosomal S12 mutation to aminoglycoside resistance in Escherichia coli via step-wise mutation analysis. Mutants of E. coli NCTC 10418 were selected in four separate progressive series (I-IV) on plates containing increasing aminoglycoside (streptomycin, neomycin, gentamicin, tobramycin, and kanamycin) concentrations. Minimum inhibitory concentrations (MICs) of these aminoglycosides were established for the most resistant mutants in each series. There was no cross-resistance between streptomycin and the other aminoglycosides tested; however there was cross-resistance between the neomycin, tobramycin and kanamycin resistant mutants. DNA sequencing of a 423bp region of the rpsL gene encoding S12 revealed a novel Lys87-->Glu mutation in the streptomycin selected resistant mutants, while there were no S12 mutations in resistant mutants resulting from selection with neomycin, gentamicin, and tobramycin and kanamycin.

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Cuba's primary health care model is presented. Unlike ambulatory care services, which are but one component of primary care, Cuba's model is a comprehensive public health approach that meets the World Health Organization's definition of primary care. The history of the development of Cuba's model is presented, including an update on the innovative neighborhood/home clinics. Achievements in health outcomes as a result of Cuba's model and the consequences for women's health care are discussed. Examples are presented of the effects on health care delivery of the economic hardship that Cuba has experienced since 1991 as a result of the loss of 85% of its trade with the former Soviet Union and the intensified U.S. embargo. A critique of Cuba's model concludes the article.

PIP: Cuba has been able to achieve some things that few Western countries have been able to achieve: equal access to health services for the entire population and equity in health status. After the 1959 revolution, community organizations conducted a census to obtain baseline demographic and epidemiologic data about the population, a literacy campaign, and sanitary and immunization campaigns. Polyclinics provided various social, environmental, and community health services free of charge. They were geographically distributed. Cuba instituted its neighborhood/home clinic model in 1984, a holistic, family, and neighborhood approach to comprehensive health care of the community. The family physician and nurse live in the neighborhood. Health education and health promotion are central to this model. The physicians and nurses are expected to conduct research and to present their findings at congresses or in journals. Cuba's infant mortality rate is not much higher than that of the US (1993, 9.4 vs. 8.3). Major causes of death in Cuba match those in developed countries, mainly heart disease and cancer. More than 95% of pregnant women attend their first prenatal visit during the first trimester. They receive prenatal care monthly unless they have a high-risk pregnancy when they receive prenatal care once a week. Infants receive well-baby care once a month. Sex education is available to everyone. All primary care facilities provide contraception. Nevertheless, the induced abortion rate is high, which concerns the government and health providers. Key effects of the economic hardship Cuba faces caused by the fall of the Soviet Union include food rationing, emigration, increased use of traditional herbs, lack of exchange of professional literature between the US and Cuba, and lack of enough paper to continue publications of medical and nursing journals. Cuba has prioritized health and education over economic development.

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The authors present an overview of Cuba's response to HIV/AIDS including: (a) the development of comprehensive health care in Cuba; (b) the epidemiology of AIDS in Cuba; (c) the sanatoria approach to treatment and recent changes; (d) the idea of comprehensive HIV/AIDS care as a basic human right; (e) the effects of the special period on the HIV/AIDS program and containment of the epidemic; and (f) a critique of Cuba's HIV/AIDS program.

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Electrophoretic variants at 28 genetic loci were analyzed in subspecies of Peromyscus maniculatus endemic to the Channel Islands of the California coast. The genetic variability within insular populations was calculated. These deer mice have relatively high levels of polymorphism for insular populations. The mean heterozygosity per individual varies in the populations, being much higher on one of the islands than the others. Nei's measure of genetic distance between groups compared on the basis of electrophoretic variants was used. His estimate of time of divergence of these groups, based on genetic distance, is applicable particularly to closely related groups. The length of time each island population has been isolated from the others was calculated and found to be consistent with the periods of isolation estimated on the basis of geological data.

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Previously unreported white spotting was found in two subspecies of the California vole, Microtus californicus. The pattern of spots on the ventral coat of the animals differs between the subspecies, and there is variation in the expressivity of the white spots. Expression of white spotting is greatly reduced by the epistatic action of another coat colour gene, the recessive buffy (bf). The incidence of white spotting, its variation in expression, and its inheritance were investigated in this study. The reproductive performance of white spotted voles were also analysed, and effects of fertility and litter size were found associated with the trait.

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