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Biomedical subjects

F Steele

Publications and source records attributed to F Steele.

13 recordsLinked to original sources
PubMed2001

Savings/credit group formation and change in contraception.

We examine the characteristics of women who chose to join a women's savings or credit group organized by Save the Children USA in a rural area of Bangladesh, and the impact of participation on contraceptive use. The data are taken from a panel survey conducted in 1993, shortly before the groups were formed, and in 1995 after interventions began. Our findings show that although demographic and socioeconomic characteristics have only a weak relationship to the decision to join a program, the treatment that a woman receives from her husband is associated with participation. We also find evidence that the credit program tends to attract women who are already using contraception. The analysis of program impact on the use of modern contraceptives reveals a positive effect of the credit program, after we adjust for this selectivity; we see no evidence of an effect of participation in a savings group.

Adult↗
PubMed2000

Painful lessons.

Explore the source record for details and available documents.

Clinical Trials as Topic↗
PubMed2000

Pulmonary availability of isotretinoin in rats after inhalation of a powder aerosol.

Repeated oral administration of chemopreventive retinoids such as isotretinoin over extended periods of time is associated with intolerable systemic toxicity. Here isotretinoin was formulated as a powder aerosol, and its delivery to the lungs of rats was studied with the aim to explore the possibility of minimizing adverse effects associated with its oral administration. Rats received isotretinoin orally (0.5, 1 or 10 mg kg(-1)) or by inhalation (theoretical dose approximately 1 or approximately 10 mg kg(-1)) in a nose-only inhalation chamber. Isotretinoin was quantitated by high-pressure liquid chromatography in plasma and lung tissue. The ratios of mean area of concentration-vs-time curve (AUC) values in the lungs over mean AUCs in the plasma for isotretinoin following single or repeated aerosol exposure surpassed those determined for the oral route by factors of between two (single low-dose) and five (single high-dose). Similarly, the equivalent ratios for the maximal peak concentrations in lungs and plasma obtained after aerosol exposure consistently exceeded those seen after oral administration, suggesting that lungs were exposed to higher isotretinoin concentrations after aerosol inhalation than after oral administration of similar doses. Repeated high doses of isotretinoin by inhalation resulted in moderate loss of body weight, but microscopic investigation of ten tissues including lung and oesophagus did not detect any significant aerosol-induced damage. The results suggest that administration of isotretinoin via powder aerosol inhalation is probably superior to its application via the oral route in terms of achieving efficacious drug concentrations in the lungs.

Administration, Inhalation↗
PubMed1999

The impact of family planning service provision on contraceptive-use dynamics in Morocco.

This article uses linked data from the 1995 Morocco DHS calendar and the 1992 Morocco DHS service-availability module to study the effect of service environment on contraceptive discontinuation, switching, and adoption of a modern method following a birth. The 1995 Morocco DHS also collected information on the source of supply for each episode of use of a modern method recorded in the calendar, allowing study of the association between the source of supply and discontinuation and switching rates. Multilevel event-history models are used to evaluate the impact of individual-level sociodemographic characteristics and community-level indicators of family planning service provision. The findings show that the presence of a nearby public health center is associated with higher modern-method adoption after a birth and lower method-failure rates; the presence of a pharmacy is associated with lower discontinuation due to side effects or health concerns. The degree of method-choice potential has a positive impact on both the rate of switching from the pill to another modern method and on modern-method adoption after a birth.

Adolescent↗
PubMed1999

Contraceptive switching in Bangladesh.

Bangladesh has experienced a substantial decline in fertility that has been achieved by means of a large increase in the use of modern methods of contraception. As contraceptive prevalence increases, aspects of contraceptive-use dynamics, including reasons for discontinuation and behavior after discontinuation, become important influences on fertility. This report uses calendar data from the 1993-94 Bangladesh Demographic and Health Survey to examine contraceptive behavior following discontinuation of modern-method use. The individual-level characteristics found to influence switching behavior include the method used, method-related difficulties with previous contraceptive use, and education. A large amount of unexplained variation in switching rates remains, however, largely at the individual level, but also at the community level for certain types of transition.

Adolescent↗
PubMed1996

Variations in familial neonatal mortality risks in four countries.

This paper investigates variations in the strength and structure of familial association in neonatal mortality risks in four populations; Bolivia, Kenya, Peru, and Tanzania. Exploratory analyses of the structure of the familial association are presented for each population. Random effects logistic models are then used to estimate the strength of familial association in neonatal mortality risks using a standard set of control variables. The results suggest that the strength of familial association in neonatal mortality risks is quite similar in these four populations which would be consistent with a biological explanation for the association. However, some differences were found, particularly in the form of the association in Peru, which may suggest at least a small role of other factors.

Africa, Eastern↗
PubMed1996

The determinants of the duration of contraceptive use in China: a multilevel multinomial discrete-hazards modeling approach.

Often in demography, individuals may change state over time for a variety of reasons. Competing-risks hazards models have been developed to model such situations. This paper describes the extension of the discrete-time competing-risks hazards model to a multilevel framework that allows for data at different levels of aggregation. The model is illustrated with data from the 1988 Chinese National Survey of Fertility and Contraceptive Prevalence, which collected complete contraceptive histories. Women may stop using a method of contraception for a number of reasons; this paper describes how one can control for correlations between the outcomes of repeated spells of contraceptive use.

Adolescent↗
PubMed1993

Overexpression of fetal human pigment epithelium-derived factor in Escherichia coli. A functionally active neurotrophic factor.

Pigment epithelium-derived factor (PEDF) is a neurotrophic protein present in low amounts in conditioned medium of cultured fetal human retinal pigment epithelial cells. Recently, the PEDF cDNA has been cloned from a fetal human cDNA library, and its derived amino acid sequence identified it as a member of the serine protease inhibitor (serpin) supergene family (Steele, F. R., Chader, G. J., Johnson, L. V., and Tombran-Tink, J. (1993) Proc. Natl. Acad. Sci. U. S. A. 90, 1526-1530). We have prepared recombinant expression constructs from the fetal human PEDF cDNA and obtained milligram amounts of biologically active PEDF from Escherichia coli. The full-length open reading frame (Met1-Pro418) and a truncated form (Asp44-Pro418) were used in our constructs. Induction from a vector containing the truncated PEDF version, named pEV-BH, produced a protein (BH) of expected size (M(r) 42,800) associated with inclusion bodies, which contained 25-40% of expressed protein. After solubilization, BH was highly purified by gel filtration and cation exchange chromatography. The NH2-terminal sequence of the purified protein matched that of the pEV-BH construct. We have conducted neurite outgrowth assays in a human retinoblastoma Y-79 cell culture system. Recombinant PEDF (BH) demonstrated neurotrophic activity, as reported for the native PEDF. Thus, unfolded and refolded in vitro BH retained a potent biological activity. In parallel experiments, protease inhibition assays were performed. Recombinant PEDF did not have an effect on trypsin, chymotrypsin, elastase, cathepsin G, endoproteinase Lys-C, endoproteinase Glu-C, or subtilisin activity, suggesting that inhibition of known serine proteases is not the biochemical pathway for the PEDF neutrophic activity.

Amino Acid Sequence↗
PubMed1990

Rhodopsin activation causes retinal degeneration in Drosophila rdgC mutant.

Drosophila rdgC (retinal degeneration-C) mutants show normal retinal morphology and photoreceptor physiology at young ages. Dark-reared rdgC flies retain this wild-type phenotype, but light-reared mutants undergo retinal degeneration. rdgC photoreceptors with low levels of rhodopsin as a result of vitamin A deprivation or a mutant rhodopsin (ninaE) gene fail to show rdgC-induced degeneration even after prolonged light treatment, demonstrating that degeneration occurs as a result of light stimulation of rhodopsin. Analysis of norpA; rdgC flies shows that the norpA-encoded phospholipase C, the target enzyme of the G protein activated by rhodopsin, is not required for rdgC-induced degeneration. Thus the rdgC+ gene product is required to prevent retinal degeneration that results from a previously unrecognized consequence of rhodopsin stimulation.

Aging↗