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Biomedical subjects

S L Albrecht

Publications and source records attributed to S L Albrecht.

17 recordsLinked to original sources
PubMed1999

The role of medical problems and behavioral risks in explaining patterns of prenatal care use among high-risk women.

OBJECTIVE: To examine the associations between maternal medical conditions and behavioral risks and the patterns of prenatal care use among high-risk women. DATA SOURCE/STUDY DESIGN: Data on over 25,000 high-risk deliveries to African American and white women using multinomial logistic regression to predict the odds of adequate-plus care relative to three other categories of care. DATA COLLECTION/EXTRACTION METHODS: Data were extracted from records maintained by the University of Florida/Shands Hospital maternity clinic on all deliveries between 1987 and 1994; records for white and for African American women were subset to examine racial differences in medical conditions, health behaviors, and patterns of prenatal care use. PRINCIPAL FINDINGS: Net of sociodemographic and fertility-related characteristics, African American and white women with late antepartum conditions and hypertension problems had significantly higher odds of receiving adequate-plus care, as well as no care or inadequate care, relative to adequate care. White women with gynecological disease and medical/surgical problems were significantly less likely to receive no care or inadequate care, as were African American women with gynecological disease. CONCLUSIONS: Maternal medical conditions explain much but not all of the adequate-plus prenatal care use. More than 13 percent of African American women and 20 percent of white women with no reported medical problems or behavioral risks used adequate-plus care. Additional research is needed to understand this excess use and its possibilities in mediating birth outcomes.

Adolescent↗
PubMed1997

The role of race and residence in determining stage at diagnosis of breast cancer.

Breast cancer kills more than 46,000 women each year. Previous research has found that minorities and those who reside in geographically remote settings are particularly vulnerable. However, virtually no research has been done on the potential "double jeopardy" faced by rural minority women. This research examines (1) the extent to which racial and residential differences contribute to differences in stage at diagnosis; (2) the existence of an interaction between race and residence, which may place black rural women at greater risk; and (3) the influence of both individual and structural characteristics on racial and residential differences. The findings indicate that rural black women are diagnosed with breast cancer much later than are black urban women or whites of either residence. A number of individual and structural variables were influential in predicting stage at diagnosis, yet none of these accounted entirely for racial differences.

Adult↗
PubMed1996

The interactive effects of race and ethnicity and mother's residence on the adequacy of prenatal care.

Adequate prenatal care is known to reduce the risks of low birth weight and neonatal death, yet nearly one quarter of all women giving birth in the United States receive delayed, inadequate or no prenatal care. This suboptimal use of prenatal care has contributed to rates of low birth weight and neonatal mortality higher than those in most other industrialized nations. This paper examines the relationships among race/ethnicity, residence, maternal sociodemographic and medical risk characteristics, and use of prenatal care in the United States. Using data from the National Maternal and Infant Health Survey, this study found important differences in prenatal care use by race/ethnicity and residence, as well as interactive effects of these variables. Single marital status, nonmetropolitan residence, poverty, low level of education, and no insurance were more strongly associated with inadequate prenatal care for whites and Hispanics than for blacks. Nonmetropolitan residents were more likely to receive inadequate care, regardless of race/ethnicity or sociodemographic characteristics. Predicted probabilities of prenatal care use by race/ethnicity and residence showed that, regardless of risk, nonmetropolitan Hispanic women had the highest probability of obtaining inadequate prenatal care. Results highlight the continued importance of race/ethnicity and rural residence in determining prenatal care use and the need to design interventions targeted to these populations.

Black or African American↗
PubMed1996

Photodissimilation of Fructose to H(inf2) and CO(inf2) by a Dinitrogen-Fixing Cyanobacterium, Anabaena variabilis.

The ability of cyanobacteria to serve as biocatalysts in the production of H(inf2) as a fuel and chemical feedstock was investigated with Anabaena variabilis. The results show that A. variabilis, when incubated under argon, dissimilated fructose to H(inf2) and CO(inf2) in a light-dependent reaction. The H(inf2) production had an obligate requirement for fructose and was heterocyst dependent, since NH(inf4)(sup+)-grown cultures lacking heterocysts failed to produce H(inf2). Differential inhibition studies with CO showed that nitrogenase is the main enzyme catalyzing the H(inf2) production. Net H(inf2) yield increased with increasing concentrations of fructose up to 10 mM in the medium. The average apparent conversion efficiency of fructose to H(inf2) (net H(inf2) produced/fructose removed from the medium) was about 10, although higher conversion efficiencies of 15 to 17 could be obtained during shorter periods and at optimum fructose concentrations. Under the same conditions, the ratio of CO(inf2) released to fructose removed from the medium was about 3.5, suggesting that only a fraction of the fructose carbon was completely oxidized to CO(inf2). Under conditions of carbon excess, which prevents H(inf2) uptake, the maximum ratio of H(inf2) to CO(inf2) was found to be 3.0. This is higher than the expected value of 2.0, indicating that water was also a source of reductant in this fructose-mediated H(inf2) production. Inhibition of H(inf2) evolution by 3-(3,4-dichlorophenyl)-1,1-dimethylurea confirmed a role for photosystem II in this process. The rate of H(inf2) production by A. variabilis SA1 was 46 ml h(sup-1) g (dry weight)(sup-1). This high rate was maintained for over 15 days. About 30% of this H(inf2) was derived from water (10 ml of H(inf2) h(sup-1) g [dry weight](sup-1)). These results show that filamentous, heterocystous cyanobacteria can serve as biocatalysts in the high-efficiency conversion of biomass-derived sugars to H(inf2) as a fuel source while simultaneously dissimilating water to H(inf2).

Journal Article↗
PubMed1996

Racial differences in adolescent drug use: the impact of religion.

Contrary to popular stereotypes, current studies of adolescent populations suggest that Black teens are less likely to use illicit drugs than are White teens. This study investigates the extent to which differences in religiosity are responsible for racial differences in drug use. Using data from a national survey of United States high school seniors, our results indicate that religion does provide some protection from drug use by adolescents. However, religiosity has less of an impact on the drug use of Black adolescents, perhaps as a result of the diverse roles of the Black church.

Adolescent↗
PubMed1989

Educational and career aspirations of secondary school students in Grenada following the American intervention.

This paper reports a study of educational and occupational aspirations of secondary school students in Grenada following the 1983 American intervention. Questionnaire data were obtained from 729 students attending 7 of the island's 18 secondary schools. A status attainment model containing parental and family characteristics was tested. It was discovered that Grenadian students have exceptionally and unrealistically high aspirations. Although the opportunity structure in Grenada is very limited compared to that in the United States, the island's students have higher levels of aspirations. The status attainment model was not very useful in explaining either educational or occupational aspirations, as the levels of explained variance were less than 5%. The implications of high aspirations and low opportunities for the future of Grenada are discussed.

Achievement↗
PubMed1980

Oxyleghemoglobin-mediated Hydrogen Oxidation by Rhizobium japonicum USDA 122 DES Bacteroids.

Oxyleghemoglobin was used to supply low concentrations of O(2) to H(2)-oxidizing bacteroids from Rhizobium japonicum USDA 122 DES. The H(2) oxidation system of these bacteroids was capable of effectively utilizing O(2) at the low concentrations of O(2) expected to be found in soybean nodules. Apparent K(m) values of approximately 10 nanomolar O(2) have been calculated for the oxyhydrogen reaction. These values include the K(m) values for both H(2) oxidation and endogenous substrate oxidation. Even in the presence of oxyleghemoglobin, H(2) additions stimulated C(2)H(2) reduction, reduced the rate of endogenous respiration and maintained the ATP contents of bacteroids. In our reconstituted oxyleghemoglobin and bacteriod system, we estimate that the H(2) oxidation system is capable of recycling all of the H(2) evolved during the N(2) fixation process.

Journal Article↗
PubMed1977

Growth of Spirillum lipoferum at constant partial pressures of oxygen, and the properties of its nitrogenase in cell-free extracts.

Spirillum lipoferum, an N2-fixing organism, was grown at constant concentrations of dissolved O2. When supplied with NH4+ aerobically, its doubling time was 1 h; when it fixed N2 microaerophilically, its doubling time was 5-5 to 7 h and the optimal PO2 for growth was 0-005 to 0-007 atm. At its optimal PO2 for growth on N2, S. lipoferum assimilated 8 to 10 mg nitrogen/g carbon substrate used; its efficiency was less at higher PO2 levels. Nitrogenase in cell-free extracts required Mg2+ and Mn2+, and the Fe-protein was activated by Rhodospirillum rubrum activating factor. The nitrogenase had an optimal pH of 7-1 to 7-4 and an apparent Km for acetylene of 0-0036 atm. Extracts of S. lipoferum lost their nitrogenase activity on storage at -18 degrees C, and activity was restored by adding purified Fe-protein from other N2-fixing bacteria.

Acetylene↗
PubMed1977

Effects of Light and Temperature on the Association between Zea mays and Spirillum lipoferum.

Zea mays was grown on a low N nutrient solution under 16 conditions of light and temperature in a crossed-gradient room in an attempt to determine whether or not variation in climatic conditions influences N(2) fixation by the association between maize and Spirillum lipoferum. Temperatures were 28, 32, 36, and 40 C and 10 C lower at night; light intensities were 500, 1,250, 2,400, and 3,000 ft-c. Plants harvested after 94 days showed no significant benefit from association with S. lipoferum either in dry weight production or in total N content; variations in temperature and light had only a small influence on N(2) fixation under the conditions tested. Measurements of total N, together with designated assumptions, indicated that less than the equivalent of 0.5 kilogram of N was fixed/hectare during the entire growing period by the maize-S. lipoferum association. Rates of C(2)H(2) reduction by replicate root samples generally were low and variable and did not correlate with the measurements of total N.

Journal Article↗
PubMed1977

Methods for Growing Spirillum lipoferum and for Counting It in Pure Culture and in Association with Plants.

Methods are described for growing Spirillum lipoferum in quantities sufficient to serve as inoculant in field trials of its associative N(2)-fixing ability with higher plants and as a source of cells for the preparation of nitrogenase, cytochromes, respiratory enzymes, etc. A heavy inoculum of S. lipoferum grown on NH(4) was transferred to a medium of minimal nitrogen content, and initial rapid growth at the expense of residual combined nitrogen was replaced later by slower growth on N(2). Conversion to N(2) fixation was prompt upon exhaustion of fixed nitrogen; growth on N(2) was most rapid at a pO(2) of 0.005 to 0.007 atm. Numbers of S. lipoferum can be estimated by diluting soil, crushed roots, or other material, and inoculating diluted samples into a stagnant semisolid medium. Development of a characteristic subsurface layer of organisms and demonstration the these organisms can reduce C(2)H(2) are presumptive evidence that they are S. lipoferum. With most-probable-number tables the observations can be converted to numbers of S. lipoferum in the samples. The most-probable-number method indicated that numbers of S. lipoferum may increase 100-fold or more in roots of maize removed from the plant and incubated for 24 h at 30 degrees C at a pO(2) initially adjusted to 0.01 atm.

Journal Article↗
PubMed1976

Factors affecting growth and nitrogen fixation of Spirillum lipoferum.

Spirillum lipoferum grows vigorously on malate, succinate, lactate, or pyruvate, moderately on galactose or acetate, and poorly on glucose or citrate. It reduces 15N2. Acetylene reduction rates decrease rapidly when the pH of the culture rises above 7.8. The organism is highly aerobic and had doubling times as low as 2 h when grown on NH4+. However, S. lipoferum reduces N2 well only under microaerophilic conditions. The optimal pO2 for acetylene reduction by stagnant cultures was 0.006 to 0.02 atm depending upon the cell density; aerated cultures grew well at dissolved O2 concentration corresponding to a pO2 of about 0.008 atm. Shaking S. lipoferum with air temporarily inactivates its nitrogenase; reactivation is inhibited by chloramphenicol. The organism assimilated 20 to 24 mg of N/g of organic acid oxidized during growth. The strains studied can be placed in two groups based upon their morphology and physiological characteristics.

Acetylene↗
PubMed1976

Carbon and ammonia metabolism of Spirillum lipoferum.

Intact cells and extracts from Spirillum lipoferum rapidly oxidized malate, succinate, lactate, and pyruvate. Glucose, galactose, fructose, acetate, and citrate did not increase the rate of O2 uptake by cells above the endogenous rate. Cells grown on NH+/4 oxidized the various substrates at about the same rate as did cells grown on N2. Added oxidized nicotinamide adenine dinucleotide generally enhanced O2 uptake by extracts supplied organic acids, whereas oxidized nicotinamide adenine dinucleotide phosphate had little effect. Nitrogenase synthesis repressed by growth of cells in the presence of NH+/4 was derepressed by methionine sulfoximine or methionine sulfone. The total glutamine synthetase activity from N2-grown cells was about eight times that from NH+/4-grown S. lipoferum; the response of glutamate dehydrogenase was the opposite. The total glutamate synthetase activity from N2-grown S. lipoferum was 1.4 to 2.6 times that from NH+/4-grown cells. The levels of poly-beta-hydroxybutyrate and beta-hydroxybutyrate dehydrogenase were elevated in cells grown on N2 as compared with those grown on NH+/4. Cell-free extracts capable of reducing C2H2 have been prepared; both Mg2+ and Mn2+ are required for good activity.

Ammonia↗
PubMedDate not supplied

Hispanic subgroup differences in prenatal care.

Within SES categories in the United States, racial and ethnic minorities generally fare less well on a variety of health-related indicators than do majority groups. Important differences exist within subgroups, however, and at present, these differences are poorly understood. In this paper we address Hispanic subgroup (Cuban American, Mexican American. Puerto Rican, and Central/South American) differences in utilization of prenatal care. Data from the 1986 and 1987 national Linked Birth/Infant Death files are used to assess patterns of prenatal care utilization across subgroups. Using Kotelchuck's Adequacy of Prenatal Care Utilization Index, we find that when controlling for other factors, Cuban American and Puerto Rican women are more likely to obtain adequate care than are Hispanic women of Mexican or Central/South American origin. Other factors important in understanding utilization patterns include marital status, education level, birthplace, and region of the country. We conclude with a discussion of the relatively weak link between prenatal care and birth outcomes and identify important cultural factors that may be important in understanding why this relationship is not stronger.

Adolescent↗
PubMedDate not supplied

The changing pattern of interracial marriage.

Recent studies have demonstrated an increased occurrence of interracial marriages in the United States, indicating important shifts in intergroup relations. The effectiveness of traditional theoretical approaches in explaining who marries whom, however, remains problematic. Recently, exchange explanations (which have typically assumed that the black partner in the union exchanges educational and economic accomplishments for the higher "status" of the white spouse) have been replaced by progressive theories emphasizing a trend away from ascriptive and toward achievement norms. We extend this approach by predicting an economic and educational gap between spouses in interracial marriages when compared with racially homogamous marriages. Using the 1980 and 1990 Public Use Microdata Sample, we find continuing evidence that racial barriers in mate selection are weakening. Further, people who intermarry, regardless of race or gender, tend to have higher educational and economic status than those in homogamous marriages. There is still limited support for the kinds of social exchanges between spouses that were implied in earlier sociological theories. We conclude that (1) socioeconomic differentials are not always consistent with the exchange perspective and (2) that recent trends are not systematically eroding these socioeconomic differentials in mate selection.

Adolescent↗