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Biomedical subjects

S C Hamel

Publications and source records attributed to S C Hamel.

9 recordsLinked to original sources
PubMed1999

The estimation of the bioaccessibility of heavy metals in soils using artificial biofluids by two novel methods: mass-balance and soil recapture.

The possible human health effects resulting from the ingestion of soil bound heavy metals can be poorly estimated if concentration of total metals in soil, rather than bioavailable fraction of metals, are incorporated into dose calculations. Information regarding bioavailability often is obtained from animal studies, which are not easily conducted and still may not represent human conditions. A rapid simulation of the bioaccessible fraction of contaminant in a soil, in which that fraction is mass soluble in gastrointestinal tract fluids, has been employed in an in vitro sequential extraction technique. Using a mass-balance analytical approach to measure bioaccessibility in four soils, the results indicated that each metal had a bioaccessible fraction less than its total metal content. Lead (Pb) in Standard Reference Material, Montana SRM 2710, was found to be 62 +/- 1% bioaccessible; Pb in contaminated soil collected from Bunker Hill, ID, USA was 70 +/- 11%. Lead in Jersey City, NJ, USA slag material was only 39 +/- 14% bioaccessible while Pb in a residential soil was 69%. Arsenic (As) and chromium (Cr) data from select soils also have bioaccessibility less than the corresponding total metal in soil, with 41 +/- 2% As in a residential soil, 66 +/- 8% As in SRM 2710, and 34 +/- 14% Cr in Jersey City slag material. Recovering the soil at the end of the in vitro extraction allowed for the determination of the insoluble fraction of total metal in soil. This recaptured soil metal mass was a valuable measurement since it greatly reduced analysis and therefore labor and time, yet also provided a reasonable estimate of bioaccessibility. It also allowed for calculation of a bioaccessibility value in a soil containing very low metal mass, which would otherwise have resulted in a non-detectable concentration at the dilutions required in the synthetic human biofluid system.

Biological Availability↗
PubMed1999

Growth of infants prenatally exposed to cocaine/crack: comparison of a prenatal care and a no prenatal care sample.

OBJECTIVE: It has not been possible to draw firm conclusions about the effects of prenatal cocaine exposure because of methodologic problems involved in the conduct of this research. This study, designed to overcome some of these methodologic problems, is a prospective, longitudinal investigation of the effects of prenatal cocaine/crack exposure on neonatal growth in two samples, one with and one without prenatal care (PC). METHODS: Women in the PC sample (n = 295) were interviewed at the end of each trimester about their use of cocaine, crack, alcohol, tobacco, marijuana, and other drugs. Women in the no prenatal care (NPC) sample (n = 98) were interviewed at delivery about their drug use during each trimester of pregnancy. In both samples, information was also obtained about sociodemographic, lifestyle, psychologic, and social support characteristics. Both samples consisted of women who were predominantly low income, single, and high school educated. Of the women, 48% in the PC sample were black; 81% in the NPC sample were black. Infants were examined during the postpartum hospital stay by project nurses who were blind to maternal substance use status. RESULTS: Women in both samples who used cocaine/crack during pregnancy were older, had lower family incomes, and used more alcohol than did women who did not use cocaine/crack during pregnancy. In addition, women in the NPC sample were more likely to be black, less educated, gained less weight during pregnancy, and used more alcohol than did women in the PC sample, regardless of cocaine use. In both samples, cocaine/crack use during early pregnancy predicted reduced gestational age, birth weight, length, and head circumference, after controlling for the significant covariates of cocaine use. In a comparison of the samples, the offspring of the NPC/cocaine group were significantly smaller than were the offspring of the PC/no cocaine group, whereas the offspring of the PC/cocaine and NPC/cocaine groups did not differ. CONCLUSIONS: These results indicate that exposure to cocaine/crack during early pregnancy decreases the intrauterine growth of exposed offspring in women with and without PC. Each of the growth parameters was affected indicating symmetric growth retardation. The adequacy of PC was not a significant factor in determining the difference between cocaine-exposed and nonexposed infants. These samples are being followed throughout childhood to determine whether there are long-term effects of prenatal cocaine/crack exposure on growth.

Birth Weight↗
PubMed1995

Early interactions between drug-involved mothers and infants. Within-group differences.

OBJECTIVE: To explore differences in maternal characteristics, mother-infant interaction, and infant development within a group of women who used cocaine, alcohol, and tobacco during pregnancy and their infants. DESIGN: Prospective survey. SETTING: Countywide, voluntary, home-based clinical intervention program. PARTICIPANTS: Thirty-two mother-infant pairs identified through a risk-assessment screen who participated in the program for 1 year. VARIABLES: Maternal characteristics, neonatal characteristics, interactional measures (Nursing Child Assessment Feeding Scale and Home Observation for Measurement of the Environment scale), and developmental assessment (Bayley Scales of Infant Development at 1 year). RESULTS: The majority of women were black, single, and unemployed. Fifteen (47%) of the infants were born prematurely; four (13%) were small for gestational age. Mean Bayley Scales of Infant Development scores were as follows: the mental development index was 99.8, and the psychomotor development index was 102.4. Older mothers (r = .41, P = .04), mothers of higher parity (r = .42, P = .02), and mothers who were more actively involved in the program (r = .41, P = .04) had higher scores on the Nursing Child Assessment Satellite Training Feeding Scale. Mothers who were better educated (r = .49, P = .009) and mothers who were more active in the program (r = .44, P = .02) had higher scores on the Home Observation for Measurement of the Environment scale. Several of the subscales of the Home Observation for Measurement of the Environment scale were significantly associated with scores on the Bayley Scales of Infant Development. CONCLUSIONS: For this group of substance-exposed infants whose mothers were receiving support services, developmental skills at 1 year were age appropriate. Despite drug abuse and poverty, there was some variability in the ability of mothers to provide a developmentally supportive environment for their infants. Those who were better organized to support infant development had infants who performed better on global developmental assessments.

Child Development↗
PubMed1992

Cocaine use and post partum psychiatric symptoms.

The association of mental health symptoms with cocaine use was studied among post partum women. Gestational cocaine use was determined by confidential interview or urine assay. A structured Psychiatric Symptom Index was used to measure mental health symptoms. Among 155 women, 24 (15%) used cocaine. Cocaine-using women had less education, higher parity, less weight gain during pregnancy, and used more cigarettes, marijuana, and opiates in pregnancy than nonusers. High frequency of symptoms (standardized Psychiatric Symptom Index score greater than or equal to 20) was found in 71% of women for the Total Index score, 81% on depression, 61% on anxiety, 36% on cognitive disturbance, and 75% on anger. No differences in Psychiatric Symptom Index Total or factor scores were associated with cocaine use.

Adult↗
PubMed1991

Cocaine and infant behavior.

Prenatal and early postnatal cocaine exposure may have lasting effects on brain development. Whereas adverse behavioral outcomes in exposed infants are plausible, they have not yet been well defined, due to methodological limitations of published studies. Improved research and clinical programs are needed to serve drug-exposed infants and their families.

Animals↗
PubMedDate not supplied

Maternal cocaine use and infant behavior.

We hypothesized that prenatal cocaine exposure results in less optimal infant behavior and more impaired maternal-infant interaction in healthy term infants. Infants were evaluated with the Neonatal Behavioral Assessment Scale (NBAS) at days 1-3 and 11-30 of age, and mother-infant pairs with the Nursing Child Assessment of Feeding Scale (NCAFS) at 7-16 weeks of age. Drug use was determined from confidential interviews, urine assays and medical records. Cocaine-exposed infants (N = 51) were no different than unexposed comparison infants (N = 60) on the first NBAS exam. On the second NBAS exam, 20 cocaine-exposed infants had slightly lower motor cluster scores compared with those of 32 unexposed infants (p = 0.01), but this difference was reduced after control for several confounding variables. The NCAFS detected no differences between groups in maternal or infant behavior. Infants in this population showed no clinically meaningful effects of cocaine exposure on behavior or maternal-infant interaction.

Behavior↗
PubMedDate not supplied

The effects of prenatal cocaine use on neonatal neurobehavioral status.

The effect of prenatal cocaine use on neonatal behavior was examined, using the Brazelton Neonatal Behavioral Assessment Scale (BNBAS), in a prospective study of women attending a prenatal clinic. Women were interviewed at the end of each trimester. Term infants were assessed with the BNBAS at day 2 (N = 165) (mean = 35.6 h) and at day 3 (N = 108) (mean = 60.1 h). Women averaged 25 years of age with 12 years of education; 48% were African-American and 20% were married. Women who used cocaine were more likely to use tobacco, alcohol, and marijuana. Regression analyses, with the Lester et al. (22) clusters as outcomes, were used to control for covariates of cocaine use such as other substance use and sociodemographic characteristics. On day 2, first, second, and third trimester cocaine/crack use were significantly related to poorer autonomic stability, second and third trimester use were related to poorer motor maturity and tone, and first and second trimester use were associated with an increased number of abnormal reflexes. These relationships were not present on day 3. These results may be transient expressions of the effect of prenatal cocaine exposure on central nervous system maturation.

Adult↗