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Biomedical subjects

B Abrams

Publications and source records attributed to B Abrams.

At least 19 recordsLinked to original sources
PubMed2006

Bacterial safety of flash-heated and unheated expressed breastmilk during storage.

Heat-treated breastmilk is one infant-feeding option recommended by the WHO to reduce mother-to-child transmission of HIV in developing countries. Flash-heat, a simple pasteurization method that a mother could perform in her home, has been shown to inactivate cell-free HIV-1. Since heating may affect the naturally occurring antimicrobial properties found in breastmilk, storing heated breastmilk may present a safety issue in resource-poor settings due to lack of refrigeration and potential contamination. To address this, we investigated the ability of flash-heat to eliminate bacteria and to prevent growth over time compared with unheated breastmilk. We collected breastmilk samples from 38 HIV positive mothers in South Africa and aliquoted them to flash-heated and unheated controls. Samples were stored at room temperature for 0, 2, 6 and 8 h and then plated and incubated for 24 h at 37 degrees C in CO(2). We performed total colony counts and identified Escherichia coli, Staphylocuccus aureus and Group A and Group B streptococci. Unheated samples had a significantly higher number of samples positive for bacterial growth at each time point (p < 0.0001), as well as mean colony-forming units (CFU)/ml in those samples that were positive at each time point (p < 0.0001). In addition, unheated samples had a significantly higher rate of bacterial propagation over time than flash-heated samples when comparing log values of CFU/ml across 0-8 h (p < 0.005). No pathogenic growth was observed in the flash-heated samples, while the unheated samples showed growth of E. coli (n = 1) and S. aureus (n = 6). Our data suggest that storage of flash-heated breastmilk is safe at room temperature for up to 8 h.

Colony Count, Microbial↗
PubMed2005

Tolerance of high-dose (3,000 mg/day) coenzyme Q10 in ALS.

An open-label dose-escalation trial was performed to assess the safety and tolerability of high doses of coenzyme Q10 (CoQ10) in ALS. CoQ10, a cofactor in mitochondrial electron transfer, may improve the mitochondrial dysfunction in ALS. In this study, CoQ10 was safe and well tolerated in 31 subjects treated with doses as high as 3,000 mg/day for 8 months.

Amyotrophic Lateral Sclerosis↗
PubMed2003

Preterm birth among African American and white women: a multilevel analysis of socioeconomic characteristics and cigarette smoking.

STUDY OBJECTIVE: Research shows that neighbourhood socioeconomic factors are associated with preterm delivery. This study examined whether cigarette smoking and individual socioeconomic factors modify the effects of neighbourhood factors on preterm delivery. DESIGN: Case-control study. SETTING: Moffit Hospital in San Francisco, California. PARTICIPANTS: 417 African American and 1244 white women, including all preterm and a random selection of term deliveries 1980-1990, excluding non-singleton pregnancies, congenital anomolies, induced deliveries, and women transported for special care. US census data from 1980 and 1990 were used to characterise the women's neighbourhoods, defined as census tracts. RESULTS: Cigarette smoking increased the risk of preterm delivery among both African American (OR=1.77, 95% confidence intervals (CI) (1.12 to 2.79)) and white women (OR=1.25, 95% CI (1.01 to 1.55)). However, cigarette smoking did not attenuate or modify the association of neighbourhood factors with preterm delivery. Among African American women, having public insurance modified the relation between neighbourhood unemployment and preterm delivery; among women without public insurance, the risk of preterm delivery was low in areas with low unemployment and high in areas with high unemployment, while among women with public insurance the risk of preterm delivery was highest at low levels of neighbourhood unemployment. CONCLUSIONS: Cigarette smoking was associated with preterm delivery, especially among African Americans. Adverse neighbourhood conditions had an influence on preterm delivery beyond that of cigarette smoking. The effects of some neighbourhood characteristics were different depending on individual socioeconomic status. Examining socioeconomic and behavioural/biological risk factors together may increase understanding of the complex causes of preterm delivery.

Black or African American↗
PubMed2001

Disparities in reported prenatal care advice from health care providers among women of Mexican origin in California.

Poorer birth outcomes have been documented among U.S.-born women of Mexican descent when compared with Mexican immigrant women. Behavioral changes that are associated with acculturation may contribute to these deteriorating outcomes. Prenatal health promotion advice can alter prenatal risk behaviors. The growing diversity of the U.S. population during the 1990s heightens the importance of examining the cultural relevance of current health promotion practices. This study examines disparities in the reported receipt of health behavior advice during pregnancy among U.S.-born women of Mexican origin and Mexican immigrant women in California. Data for the analysis are from the 1994-95 California Pregnancy Risk Assessment Monitoring System. The study sample includes 1,423 women of Mexican descent. All participants had a live birth in California between January 1994 and December 1995. Women were interviewed about the prenatal counseling they received related to diet, smoking, and alcohol use. Logistic regression was used to analyze the likelihood of reporting advice after controlling for sociodemographic and health system characteristics. Immigrant women were more likely than the U.S.-born to report receipt of prenatal advice on smoking, alcohol, and diet (OR = 1.83, p < .05) despite evidence of the lower prevalence of related health risks among Mexican-born women. Culturally appropriate prenatal counseling would emphasize the maintenance of traditional protective behaviors among less acculturated foreign-born women, and the prevention or cessation of those risk behaviors among the more acculturated women.

Journal Article↗
PubMed2001

Body mass index in mid-life women: relative influence of menopause, hormone use, and ethnicity.

OBJECTIVE: To assess the relative influence of menopausal status and hormone use on body mass index (BMI) among a multiethnic sample of mid-life women. DESIGN: Cross-sectional telephone survey conducted at seven sites where each site targeted an ethnic minority group and Caucasians as part of Study of Women's Health Across the Nation (SWAN). SUBJECTS: A total of 7181 Caucasians, 3949 African-Americans, 1660 Hispanics, 562 Chinese Americans, and 803 Japanese Americans between ages of 40 and 55 y residing in or near Boston, Chicago, Detroit, Los Angeles, Newark, NJ, Oakland, CA, and Pittsburgh, PA. MEASUREMENTS: Self-reported BMI based on weight in kg divided by height in m(2) menopausal status, physical inactivity, postmenopausal hormone use, ethnicity, and age in years. RESULTS: Compared to premenopausal women (covariate adjusted M=27.3), women reporting a surgical menopause (M=28.2) or being in the perimenopausal transition (M=27.7 for early and 27.9 for late perimenopause) had higher BMI. Women reporting a natural menopause (M=27.4) did not have a higher BMI than premenopausal women, after adjusting for chronological age and other covariates. Hormone use was associated with lower BMI (M=26.5 vs 27.3). A comparison of effect sizes showed that menopausal status (F=13.1), followed by chronological age (F=24.0), were the least powerful predictors of BMI, whereas the more powerful predictors were physical activity level (F=1377.1) and ethnicity (F=400.5). CONCLUSIONS: The menopausal transition affects body mass index in mid-life, but the effect is small relative to other influences. Interventions to increase physical activity are highly recommended to prevent increases in adiposity common in mid-life.

Adult↗
PubMed2001

Does the pattern of postpartum weight change differ according to pregravid body size?

OBJECTIVES: To examine differences in the pattern of weight changes during and after pregnancy among four pregravid body mass index (BMI) groups. STUDY DESIGN: Prospective cohort study of women who had two consecutive births at the University of California, San Francisco (UCSF) between 1980 and 1990. MEASUREMENTS: Maternal body weights were available before conception and delivery, and at 6 weeks postpartum for the first (index) pregnancy, and before conception for the second study pregnancy. Height and two pregravid weights were self-reported. Weights at delivery and 6 weeks postpartum were measured. Net delivery weight was defined as delivery weight minus infant birth weight. Three non-overlapping sequential weight changes were constructed: (1) net gestational gain (net delivery weight minus pregravid weight at the index pregnancy); (2) early net postpartum weight change (6-week postpartum weight minus net delivery weight); and (3) late postpartum weight change (pregravid weight at the second pregnancy minus 6-week postpartum weight). SUBJECTS: A total of 985 healthy women (age 18-41 y) from four race/ethnicity groups (Asian, Hispanic, black and white) who had a singleton, full-term, live birth for the index pregnancy followed by a second consecutive birth. RESULTS: Four race/ethnicity groups were combined (no interaction) to contrast average weight changes among pregravid BMI groups. Means adjusted for eight covariates (parity, race/ethnicity, education, mode of delivery, smoking, hypertension of pregnancy, age, height) and time intervals were not altered appreciably. Early net postpartum weight losses were similar for all pregravid BMI groups. Late (median of 2 y) postpartum weight losses were 4 kg higher in the low and average BMI groups compared with the highest BMI group. About half of the net gestational gain was lost by 6 weeks postpartum, and the percentage that was lost decreased over time. CONCLUSIONS: This study suggests that early postpartum weight loss does not vary by maternal pregravid BMI group, but late postpartum weight change does. Serial weight measurements are needed in epidemiologic studies to differentiate retention of gestational gain from weight gain during the late postpartum period.

Adolescent↗
PubMed2001

The relationship of neighborhood socioeconomic characteristics to birthweight among 5 ethnic groups in California.

OBJECTIVES: This study sought to examine relationships between neighborhood socioeconomic characteristics and birthweight, accounting for individual socioeconomic characteristics, among 5 ethnic groups. METHODS: Birth records were linked to census block-group data for 22 304 women delivering infants at 18 California hospitals during 1994-1995. Information on income and additional factors was obtained from a surveyed subset of 8457 women. Neighborhood levels of poverty, unemployment, and education were examined. RESULTS: After adjustment for mothers' individual socioeconomic characteristics and other risk factors, less-favorable neighborhood socioeconomic characteristics were associated with lower birthweight among Blacks and Asians. No consistent relationship between neighborhood socioeconomic characteristics and birthweight was found among Whites, US-born Latinas, or foreign-born Latinas overall, but birthweight increased with less-favorable neighborhood socioeconomic characteristics among foreign-born Latinas in high-poverty or high-unemployment neighborhoods. These findings were not explained by measured behavioral or cultural factors. CONCLUSIONS: In addition to individual socioeconomic characteristics, living in neighborhoods that are less socioeconomically advantaged may differentially influence birthweight, depending on women's ethnicity and nativity.

Adolescent↗
PubMed2000

The relative importance of gestational gain and maternal characteristics associated with the risk of becoming overweight after pregnancy.

OBJECTIVES: To assess the relationships between gestational gain, race/ethnicity, reproductive history, age, education and the risk of becoming overweight after pregnancy. STUDY DESIGN: Prospective cohort study of adult women from four race/ethnicity groups who had two consecutive births between 1980 and 1990 at the University of California, San Francisco (UCSF). MEASUREMENTS: Height and pregravid weights for each pregnancy were self-reported. Women were classified as overweight or not overweight according to the Institute of Medicine (IOM) criteria for pregnancy. Gestational gain was defined as the difference between the pregravid weight and the last weight before delivery of the first study pregnancy. SUBJECTS: 1300 healthy women aged 18-41 y who had a singleton, full-term, live birth (index or first study pregnancy) followed by a second birth. Self-reported pregravid weights and heights were used to calculate body mass index (BMI). Women with a pregravid BMI below 26.0 kg/m2 before the index pregnancy were classified as not overweight (n = 1128). Overweight status following the index pregnancy was based on pregravid BMI for the second pregnancy. RESULTS: Seventy-two women (6.4%) became overweight following the index pregnancy. Statistically significant independent predictors of the risk of becoming overweight included: maternal age 24-30 vs above 30 y, high gestational gain, short interval from menarche to first ever birth ( < 8 y), and young age at menarche ( < 12 y). The risk of becoming overweight was increased 2.5-3 times for each of these risk factors. Whites were 4.5 times more likely to become overweight than Asians, but blacks and Hispanics did not appear to differ from whites. Parity, time interval, smoking habit, education, marital status and other factors were not associated with the risk of becoming overweight. CONCLUSIONS: These findings suggest that young age at menarche, maternal age and short time from menarche to first ever birth may be as important as high gestational weight gain in determining the risk of becoming overweight after pregnancy.

Adolescent↗
PubMed2000

Defining preterm delivery--the epidemiology of clinical presentation.

It is possible that preterm delivery is not a single entity but a cluster of conditions with different aetiologies that ultimately result in the delivery of an infant before 37 completed weeks of gestation. Whereas some researchers have reported aetiological heterogeneity, others have found no differences between subtypes or have disputed the desirability and utility of classifying preterm birth into subtypes. This study explores the relationship of maternal risk factors to type of preterm delivery in a cohort of over 7000 black and white women delivering singleton infants at the University of California, San Francisco's Moffitt Hospital between 1980 and 1990. Although the magnitude of the effect of individual risk factors differed between preterm delivery subtypes, the set of risk factors significantly associated with both categories of spontaneous preterm delivery was identical, while that associated with medically indicated preterm births was different. This study indicates that whereas the distinction between spontaneous preterm deliveries and those that are medically indicated seems valid, distinguishing between types of spontaneous preterm births may not lead to useful aetiological inferences.

Adolescent↗
PubMed2000

Pregnancy weight gain: still controversial.

During the 20th century, recommendations for maternal weight gain in pregnancy were controversial, ranging from rigid restriction to encouragement of ample gain. In 1990, the Institute of Medicine (IOM) recommended weight-gain ranges with the primary goal of improving infant birth weight. These guidelines were widely adopted but not universally accepted. Critics have argued that the IOM's recommendations are unlikely to improve perinatal outcomes and may actually increase the risk of negative consequences to both infants and mothers. We systematically reviewed studies that examined fetal and maternal outcomes according to the IOM's weight-gain recommendations in women with a normal prepregnancy weight. These studies showed that pregnancy weight gain within the IOM's recommended ranges is associated with the best outcome for both mothers and infants. However, weight gain in most pregnant women is not within the IOM's ranges. All of the studies reviewed were observational and there is a compelling need to conduct experimental studies to examine interventional strategies to improve maternal weight gain with the objective of optimizing health outcomes.

Birth Weight↗
PubMed1998

Determination of CD4 antigen density on cells: role of antibody valency, avidity, clones, and conjugation.

The number of R-phycoerythrin (R-PE)-conjugated antibodies bound to a cell can be quantitated on a flow cytometer by using beads with known numbers of attached R-PE molecules (QuantiBRITE PE). Using these reference beads, we have observed that a number of factors affect the accuracy of the quantitation and conclusions about epitope density. These factors include valence of antibody binding, the use of antibody fragments (Fab's) versus intact monoclonal antibodies (mAb's), fixation, the purity of the conjugate (i.e., percentage of 1:1 ratios), dissociation rate, the use of washed versus unwashed preparations, and the location of epitope on target antigen. We used CD4 on T cells as a model to explore these challenges in detail. We conclude that CD4+ T cells bind approximately 49,000 CD4 (Leu 3a) antibody molecules, that this binding is bivalent, and therefore that there are approximately 98,000 CD4 antigen molecules on the surface of these cells.

Antibodies, Monoclonal↗
PubMed1998

Staining of cell surface human CD4 with 2'-F-pyrimidine-containing RNA aptamers for flow cytometry.

We have used recombinant human CD4 presented on beads as an affinity matrix to screen a 2'-F-pyrimidine-containing RNA library with a complexity of approximately 10(14) molecules. Affinity-selected aptamers bind recombinant CD4 with low nanomolar equilibrium dissociation constants. These high-affinity aptamers conjugated to different fluorophores such as fluorescein and phycoerythrin were used to stain cells, expressing human CD4 on cell surface, for analysis by flow cytometry. Aptamers, conjugated to fluorophores, stained mouse T cells that express human CD4 on the surface, but not the control mouse T cells lacking human CD4. The control cells, however, do express mouse CD4 whose extracellular domain has 55% sequence identity to the human form. These human CD4-specific aptamers selectively stained CD4(+) T cells in a preparation of human peripheral blood mononuclear cells. These results and others suggest that aptamers are emerging as a versatile class of molecules that can be used for various diagnostic applications performed under different formats or platforms.

Amino Acid Sequence↗
PubMed1998

Conversion of psoriasis patients from the conventional formulation of cyclosporin A to a new microemulsion formulation: a randomized, open, multicentre assessment of safety and tolerability.

OBJECTIVE: To assess the safety, tolerability and efficacy of a new cyclosporin A (CyA) microemulsion formulation, Sandimmun Neoral (Neoral), in patients with severe psoriasis that was stable on CyA administered as Sandimmun (SIM). METHODS: In this 24-week, open, randomized, prospective, multicentre trial, 28 patients continued on the same dosage of SIM, while 30 converted to Neoral at 2.5 mg/kg/day or a dosage equivalent to their pre-conversion SIM dosage. During the study, dosages could be adjusted to maintain efficacy, because of adverse events or after disease stabilization. The maximum permitted dosage for either formulation was 5.0 mg/kg/day. Primary efficacy criteria were change in Psoriasis Area and Severity Index (PASI) from baseline and time to relapse. RESULTS: The dosage was increased to maintain efficacy in 22 patients (Neoral 13; SIM 9) and 20 dose reductions for safety were required (Neoral 14, SIM 6). In both groups, PASI scores remained stable throughout and relapses were primarily a result of dosage reduction after disease stabilization. No significant difference was found between groups in the proportion of patients remaining relapse-free. Adverse events were recorded in 20 patients receiving Neoral and 14 receiving SIM. Most drug-related events were of mild or moderate severity and reflected the known CyA side-effect profile. Dose titration guidelines ensured that mean blood pressure and serum creatinine concentrations remained stable in both groups. CONCLUSIONS: If the guidelines for CyA use are followed and the Neoral dosage does not exceed 5 mg/kg/day, conversion of stable patients with severe psoriasis from SIM to Neoral should present no clinically relevant safety or tolerability problems and efficacy of treatment is maintained.

Adolescent↗
PubMed1997

A critical review of the relationship between gestational weight gain and preterm delivery.

OBJECTIVE: To review the relationship between gestational weight gain and preterm delivery. DATA SOURCES: We identified published studies through Medline searches (for the period 1980-1996), and we reviewed bibliographies from published articles. METHODS OF STUDY SELECTION: We excluded non-English-language articles and articles that used total weight gain, unadjusted for gestational age. Thirteen articles were identified for review. TABULATION, INTEGRATION AND RESULTS: Eleven of the 13 studies reported a significant association between maternal weight gain and risk of preterm delivery, and most reported that inadequate rate of maternal weight gain was associated with an increased risk (approximately 50-100%) of preterm delivery. Studies examining pattern of gain noted that a low rate of gain during the latter part of pregnancy (but not early pregnancy) was associated with an increased risk of preterm delivery (also approximately 50-100%). The studies' findings were relatively consistent, despite the use of diverse samples, study designs, and analytic strategies. CONCLUSION: The evidence suggests that a lower rate of weight gain during pregnancy is associated with an increased risk of preterm delivery, and that a slow rate of gain during the latter part of pregnancy may be particularly important. To improve our understanding of the mechanisms of these relationships, future studies should examine pattern of gain; they should stratify analyses on the different subtypes of preterm delivery and provide more detailed descriptions of methods for assessing gestational duration.

Delivery, Obstetric↗
PubMed1997

The association of pattern of maternal weight gain with length of gestation and risk of spontaneous preterm delivery.

Monitoring weight gain during pregnancy may be useful in detecting pregnancies that are at increased risk of early delivery. This study examines 7259 deliveries that occurred at the University of California, San Francisco's Moffitt Hospital from 1980 to 1990. Obese women, women with diabetes or hypertension during pregnancy, deliveries with congenital malformations and non-spontaneous preterm deliveries were excluded. Pattern of gain was assessed by fitting a quadratic curve to each woman's series of weight and date measurements, using simple regression techniques. The parameters from this curve were used to develop a variable for pattern of gain that reflects how much an individual's pattern of gain differs from a linear pattern of gain. Multivariable linear and logistic regression analyses indicate that patterns of gain that deviate greatly from the average pattern of gain (i.e. patterns that show a marked speeding up or slowing down of gain towards the end of pregnancy) are associated with significantly shorter gestational age and confer a significantly increased risk of spontaneous preterm delivery. The results suggest that monitoring weight gain during pregnancy is important, although more specific studies are needed to understand the mechanisms by which weight gain pattern relates to preterm delivery before appropriate interventions can be developed.

Adult↗