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Biomedical subjects

A A Mitchell

Publications and source records attributed to A A Mitchell.

At least 37 records · Page 2Linked to original sources
PubMed1997

Multivitamin supplementation and multiple births.

It is well established that maternal multivitamin supplementation reduces the risk of neural tube defects and evidence suggests that it may be associated with other reproductive outcomes. The present study was prompted by a report from a randomized trial in Hungary which showed a 40% increase in multiple births among periconceptional vitamin users. Retrospectively collected data on multivitamin supplementation were obtained on multiple and singleton births from three separate studies: Atlanta Birth Defects Case-Control Study (ABDCCS) malformed and nonmalformed infants born 1968-1980, California Birth Defects Monitoring Program (CBDMP) malformed and nonmalformed infants born 1987-1989, and Boston University Slone Epidemiology Unit Birth Defects Study (SEU-BDS) malformed infants born 1987-1994. Supplementation was divided into three mutually exclusive categories based on timing: "periconceptional" use--before through at least the third month after conception; "early" use--beginning in the first month and continuing through at least the third month after conception; and "later" use--beginning in the second or third month after conception. For periconceptional use, four of five datasets showed a 30 to 60% greater prevalence of supplementation among mothers of multiple births. In contrast, this pattern was not evident for "early" and "later" use. Overall, the study findings are tentative, due to a lack of consistency across all five datasets and they should not alter recent recommendations related to folate supplementation for the prevention of neural tube defects.

Congenital Abnormalities↗
PubMed1997

Renal function after short-term ibuprofen use in infants and children.

OBJECTIVE: To test the hypothesis that short-term use of ibuprofen increases the risk of impaired renal function in children. STUDY DESIGN: Randomized, double-blind acetaminophen-controlled clinical trial. Children with a febrile illness were enrolled from outpatient pediatric and family medicine practices and randomly assigned to receive either acetaminophen suspension or one of two dosages of ibuprofen suspension (5 mg/kg or 10 mg/kg) for fever control. RESULTS: Mean blood urea nitrogen levels on admission among children admitted to hospital and assigned ibuprofen 5 mg/kg (n = 96), ibuprofen 10 mg/kg (n = 102), and acetaminophen 12 mg/kg (n = 87) were 4.1, 3.8, and 3.9 mmol/L, respectively. The corresponding creatinine levels were 43, 41, and 43 micromol/L, respectively. The prevalence of a creatinine level >62 micromol/L was 9.5% overall and did not vary by antipyretic assignment. Among 83 children hospitalized with dehydration, the mean creatinine level was 44 micromol/L, and the prevalence of an elevated creatinine was 14%; neither measure varied by antipyretic assignment. CONCLUSION: Although renal failure in children has been reported after ibuprofen use, these data suggest that for short-term use the risk of less severe renal impairment, as reflected by blood urea nitrogen and creatinine levels, is small and not significantly greater than that after acetaminophen use.

Acetaminophen↗
PubMed1996

Case-control study of periconceptional folic acid supplementation and oral clefts.

There is consistent evidence that the risk of neural tube defects is decreased by periconceptional supplementation with folic acid. A similar protective effect has been postulated for oral clefts. A case-control study was conducted in greater metropolitan Boston; Massachusetts; Philadelphia, Pennsylvania; and southeastern Ontario, Canada, from 1988 through 1991 to test the hypothesis that folic acid supplementation during the periconceptional period reduces the risk of oral clefts. Crude and multivariate-adjusted relative risks were calculated for all oral clefts (n = 303), cleft palate (n = 108), and cleft lip with or without cleft palate (n = 195). Controls (n = 1,167) were liveborn or stillborn infants less than age 6 months who had various congenital anomalies other than oral clefts, neural tube defects, or other "midline defects." Adjusted relative risks and 95 percent confidence intervals for daily folic acid supplementation during the periconceptional period were: oral clefts, 1.1 (95% confidence interval (CI) 0.8-1.7), cleft palate, 0.9 (95% CI 0.5-1.6), and cleft lip with or without cleft palate, 1.3 (95% CI 0.8-2.1). These findings do not support a protective association between the periconceptional use of folic acid supplements and the risk of oral clefts.

Case-Control Studies↗
PubMed1996

Prepregnant weight in relation to risk of neural tube defects.

OBJECTIVE: To examine the relation between prepregnant weight and the risk of neural tube defects (NTDs). DESIGN: Data were collected from 1988 to 1994 in a case-control surveillance program of birth defects. SETTING: Study subjects were ascertained at tertiary care centers and birth hospitals in the greater metropolitan areas of Boston, Mass, and Philadelphia, Pa, and in southeastern Ontario. PARTICIPANTS: Cases were 604 fetuses or infants with an NTD identified within 6 months of delivery. Controls were 1658 fetuses or infants with other major malformations identified within 6 months of delivery. For 1992 to 1994, there were 93 control infants without major malformations. MAIN OUTCOME MEASURE: Relative risk of NTDs in infants or fetuses for different maternal weights. RESULTS: Relative to women who weighed 50 to 59 kg, risk of NTDs increased from 1.9 (95% confidence interval [CI], 1.2 to 2.9) for women weighing 80 to 89 kg to 4.0 (95% CI, 1.6 to 9.9) for women weighing 110 kg or more. When women were classified according to daily intake above or below the recommended level of 400 micrograms of folate, approximate threefold increases in risk were estimated for the heaviest weights in both groups. Intakes of 400 micrograms of folate or more reduced risk of NTDs by 40% among women weighing less than 70 kg, but no risk reduction was observed among heavier women. CONCLUSION: The risk of NTDs increased with increasing prepregnant weight, independent of the effects of folate intake.

Adult↗
PubMed1996

Black soil blindness: a new mycotoxicosis of cattle grazing Corallocytostroma-infected Mitchell grass (Astrebla spp).

A new, fatal mycotoxicosis of cattle has been recognised in north-western Australia. A feeding trial confirmed the toxicity of a previously unknown species of Corallocytostroma that grows on Mitchell grass (Astrebla spp). The disease has been colloquially named 'black soil blindness' because its most prominent features are its confinement to pastures on black soil, and blindness and death of affected animals. Over 500 cattle have died and considerable subclinical disease in present. Above average wet season rainfall and extended growing seasons may explain the emergence of the fungus. The disease is important because cattle production in large areas of Australia utilise Mitchell grass pastures.

Animals↗
PubMed1996

Ethnically sensitive messengers: an exploration of racial attitudes of health-care workers and organ procurement officers.

This study examined attitudes of organ procurement employees toward black and Hispanic clients. Participants completed the Situational Attitude Scale (SAS). Findings showed that participants favored the person of color over the neutral, race-unspecified person when the person of color was in a subservient role. While the SAS items were not specific to organ donation scenarios, some inferences may be can be made. White organ procurement employees, dealing with white people significant to the donor, may experience little anxiety when placed in the role of service provider. However, when dealing with donors of color, white procurement employees may experience some cognitive dissonance. White employees may be comfortable being served by people of color, but uncomfortable serving people of color. This feeling, coupled with a lack of cross-cultural understanding, may create a communication barrier between procurement and donor communities.

Black or African American↗
PubMed1995

A pregnancy-prevention program in women of childbearing age receiving isotretinoin.

BACKGROUND: Isotretinoin is effective in treating severe acne, but it is also teratogenic. To minimize pregnancies among exposed women, the manufacturer, together with the U.S. Food and Drug Administration, implemented a multicomponent Pregnancy Prevention Program in 1988. We report the results of an ongoing survey designed to assess compliance with this program. METHODS: Treated women enrolled in the survey through their physician, by filling out a form in the medication package, or by calling a toll-free telephone number. They were randomly assigned to be followed by telephone or by mail. Telephone interviews were conducted at the start of therapy, in the middle of it, and 6 months after it ended; mailed questionnaires were completed 6 months after therapy ended (median duration of therapy, 20 weeks). RESULTS: Between 1989 and 1993, 177,216 eligible women enrolled in the survey. Interviews with 24,503 women within one month of enrollment revealed that 99 percent had been told to avoid pregnancy. At that time, approximately 54 percent were not sexually active (of whom 37 percent used contraception) and 42 percent were sexually active (of whom 99 percent used contraception); 4 percent were infertile. Among 124,216 women with completed telephone or mail follow-up results, there were 402 pregnancies during therapy (3.4 per 1000 courses of isotretinoin); 72 percent of the pregnant women had elective abortions, 16 percent spontaneous abortions, 3 percent ectopic pregnancies, and 8 percent live births. CONCLUSIONS: The pregnancy rate among women receiving isotretinoin therapy was substantially lower than that in the general population and was compatible with the characteristics and behavior of the enrolled women.

Abnormalities, Drug-Induced↗
PubMed1995

When a randomised controlled trial is needed to assess drug safety. The case of paediatric ibuprofen.

Drugs are frequently made available for use before risks of rare but serious reactions have been identified and quantified. While this situation may be acceptable for drugs used to treat serious conditions, greater information on safety is needed for drugs used to treat less serious conditions, and particularly those medications available without prescription. Spontaneous reports and observational studies can provide useful data in most instances, but nonrandomised studies are inadequate in the presence of confounding by indication (i.e. when patients treated with a drug differ in their underlying risk of adverse outcome from patients given alternate treatments, independent of the effect of the drug). Such is the case in the US with regard to the use of paediatric ibuprofen as an antipyretic. In this setting, a rigorous and large randomised controlled trial is needed to provide valid and statistically stable risk estimates. A trial of this kind is a feasible way to develop clinically meaningful data on safety with respect to rare but serious adverse reactions.

Drug-Related Side Effects and Adverse Reactions↗
PubMed1994

Ovulation induction and risk of neural tube defects.

The relation between use of ovulation-inducing drugs and risk of neural tube defects (NTDs) was studied in a case-control surveillance programme. The frequency of any use of such drugs during the 6 months before the last menstrual period or during pregnancy was 3.0% for 1034 mothers of infants and fetuses with NTDs (cases) and 2.8% for 4081 mothers of those with other major congenital malformations (controls) (relative risk 1.1, 95% CI 0.8-1.7). Relative risks for clomiphene and for hormones were 0.8 (0.5-1.3) and 1.5 (0.7-3.4), respectively. These data suggest that use of ovulation-inducing drugs before conception does not increase the risk of NTDs.

Case-Control Studies↗
PubMed1994

A severe outbreak of E. coli O157 in two psychogeriatric wards.

In October 1990 there was a severe outbreak of Escherichia coli O157 in two psychogeriatric wards of a large psychiatric hospital in Lanarkshire. There were 11 cases (eight patients and three staff), of whom four died (all patients). Two cases, one staff and one patient (the likely index case) were identified serologically after the outbreak was over. E. coli O157 was not cultured from any food, water or milk samples, and the evidence suggests that the index case had eaten food brought into the hospital. The results also suggest that the incubation period of the organism may be longer than is currently recognized, particularly for person-to-person spread. A Fatal Accident Inquiry was held into the deaths, and the Sheriff's Determination is discussed together with the implications of the results for infection control procedures.

Adolescent↗