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Biomedical subjects

M Bracken

Publications and source records attributed to M Bracken.

14 recordsLinked to original sources
PubMed1992

Risk of congenital malformations associated with proximity to hazardous waste sites.

Concern about environmental pollutants has increased; however, it remains unclear whether chronic exposures to toxic chemicals in the environment occur at doses sufficient to produce adverse health effects in humans. To date, community studies have not adequately addressed this question. In this study, the authors linked two existing data bases of the New York State Department of Health to evaluate the relation between congenital malformations and residential proximity to hazardous waste sites in New York State. A total of 9,313 newborns with congenital malformations and 17,802 healthy controls living in proximity to 590 hazardous waste sites in 1983 and 1984 were evaluated. After the authors controlled for several possible confounding factors, results indicated that maternal proximity to hazardous waste sites may carry a small additional risk of bearing children with congenital malformations (odds ratio (OR) = 1.12, 95% confidence interval (Cl) 1.06-1.18). Higher malformation rates were associated with both a higher exposure risk (no exposure risk: OR = 1.00; low exposure risk: OR = 1.09, 95% Cl 1.04-1.15; high exposure risk: OR = 1.63, 95% Cl 1.34-1.99) and documentation of off-site chemical leaks (not exposed: OR = 1.00; exposed, but no leaks at site: OR = 1.08, 95% Cl 1.02-1.15; exposed, and leaks found at site: OR = 1.17, 95% Cl 1.08-1.27). The increased rates detected may be important in terms of their public health implications. Further research is necessary to strengthen causal inferences regarding the teratogenicity, of waste site exposure.

Adolescent↗
PubMed1992

Congenital defects and electric bed heating in New York State: a register-based case-control study.

Exposure to 60-cycle electromagnetic fields has been hypothesized to be a cause of childhood cancer and congenital defects. Because electric bed heaters are a major source of variation in electromagnetic field exposure in the population, the authors conducted a case-control study in 1988-1989 to examine the relations between congenital defects and the use of electric blankets and heated waterbeds. Cases were identified by the New York State Congenital Malformations Registry as babies with cleft palate (n = 121), cleft lip with or without cleft palate (n = 197), born in 1983-1984, and anencephalus and spina bifida (n = 224), born in 1983-1986, all to upstate New York residents. Controls were selected at random from birth registrations individually matched to cases by maternal race, age, home county, month of last menses, and child's sex. Information on periconceptional electric blanket and heated waterbed use as well as known and suspected risk factors for defects was obtained from questionnaires mailed to the mothers. Matched odds ratio estimates and 95% confidence intervals (CIs) for electric blanket use relative to nonuse were 0.8 (95% CI 0.3-2.1) for cleft palate, 0.7 (95% CI 0.3-1.3) for cleft lip, and 0.9 (95% CI 0.5-1.6) for neural tube defects. The respective odds ratios for heated waterbed use were nearly identical to these. Adjustment for potential confounding factors (maternal education, vitamin use, smoking) and stratification by season of conception and bed heat control setting had no meaningful effect on odds ratios. These results suggest that 60-cycle fields do not cause neural tube and oral cleft defects.

Adult↗
PubMed1992

Respiratory disease in very-low-birthweight infants after prenatal thyrotropin-releasing hormone and glucocorticoid. TRH Study Group.

Although prenatal glucocorticoid treatment reduces neonatal respiratory morbidity, respiratory distress syndrome and chronic lung disease (CLD) develop in many very-low-birthweight infants despite therapy. To investigate the effect of additional prenatal treatment with thyrotropin-releasing hormone (TRH), we did a multicentre, blinded, randomised trial. 404 women with threatened preterm delivery at less than 32 weeks' gestation received betamethasone plus TRH (4 doses of 400 micrograms 8-hourly) or betamethasone plus placebo. 103 infants who were fully treated and of less than 1500 g birthweight were evaluated during the neonatal period. TRH treatment (55 infants) did not affect the total incidence of respiratory distress syndrome (47% vs 58% in controls) or of severe respiratory distress syndrome (13% vs 25% in controls, p = 0.11). CLD (defined as requirement for supplemental oxygen at 28 days after birth) developed in significantly fewer TRH-treated infants (18% vs 44% of controls, p less than 0.01). The unadjusted relative risk of CLD with TRH therapy was 0.40 (95% CI 0.26-0.80, p less than 0.05), and this was not materially changed after adjustment for potentially modifying variables. There were significantly fewer adverse outcomes, defined as death or continuing oxygen requirement, in the TRH group than in the steroid-alone group both at 28 days and when infants reached 36 weeks' postconceptional age. The incidence of other complications of prematurity was similar in the two groups. Prenatal TRH reduces the incidence of chronic lung disease among betamethasone-treated infants.

Betamethasone↗
PubMed1992

Plasma thyroid hormones and prolactin in premature infants and their mothers after prenatal treatment with thyrotropin-releasing hormone.

We assayed TSH, triiodothyronine, free thyroxine, and prolactin (PRL) in plasma of women and infants participating in a trial of prenatal thyrotropin-releasing hormone (TRH) treatment for prevention of newborn lung disease. Women in labor at 26-34 wk of gestation received 400 micrograms of TRH i.v. every 8 h (one to four doses) plus 12 mg betamethasone (one or two doses); controls received saline plus betamethasone. Mean cord concentrations in control infants were TSH 9.7 mU/L, triiodothyronine 0.6 nmol/L (40.2 ng/dL), free thyroxine 14.4 pmol/L (1.13 ng/dL), and PRL 67.6 micrograms/L. TRH increased maternal plasma TSH by 100% at 2-4 h after treatment and decreased levels by 28-34% at 5-36 h. In cord blood of treated infants delivered at 2-6 h, TSH, triiodothyronine, and PRL were all increased about 2-fold versus control, and free thyroxine was increased 19%; the response was similar after one, two, three, or four doses of TRH. In treated infants delivered at 13-36 h, cord TSH and triiodothyronine levels were decreased 62 and 54%, respectively, and all thyroid hormones were lower after birth at 2 h of age versus control. We conclude that prenatal TRH administration increases thyroid hormones and PRL in preterm fetuses to levels similar to those normally occurring at term. Pituitary-thyroid function is transiently suppressed after treatment to a greater extent in fetus than mother, and infants born during the early phase of suppression do not have the normal postnatal surge in thyroid hormones.

Betamethasone↗
PubMed1991

[Premature rupture of membranes at preterm. Meta-analysis of the effect of steroids on the prevention of respiratory distress syndrome].

The use of steroids in premature rupture of the membranes is controversial. We used meta-analysis of published results to evaluate the effect of steroid treatment to prevent fetal respiratory distress syndrome associated to premature rupture of the membranes and found that a 30% reduction in the rate of this complication was observed in patients receiving steroids. The 95% confidence interval for relative risk was 0.610 to 0.815. However, infectious complication of the mother increased (mean relative risk 1.68, 95% Cl 1.16-2.44) but not those of the neonate. These results support the use of steroids in order to prevent fetal respiratory distress syndrome in pregnant women with premature rupture of membranes.

Analysis of Variance↗
PubMed1990

19F-n.m.r. studies of ligand binding to 5-fluorotryptophan- and 3-fluorotyrosine-containing cyclic AMP receptor protein from Escherichia coli.

Two fluorine-containing analogues of the cyclic AMP receptor protein (CRP) from Escherichia coli were prepared by biosynthetic incorporation of 5-fluorotryptophan (5-F-Trp) and 3-fluorotyrosine (3-F-Tyr). The 19F-n.m.r. spectrum of the [5-F-Trp]CRP showed two signals corresponding to the two tryptophan residues, and that of the [3-F-Tyr]CRP showed six signals (two overlapping) corresponding to the six tyrosine residues: these results are as expected for a symmetrical dimer. A comparison of the 19F-n.m.r. spectra of the CRP analogues in the presence and in the absence of cyclic AMP reveals that the chemical shifts of both tryptophan residues and of two of the six tyrosine residues show differences. Since none of these residues is in direct contact with the bound nucleotide (although Trp-85 is fairly close), these shift changes must arise from induced conformational effects. The 19F-n.m.r. spectra of complexes with cyclic GMP showed chemical-shift perturbations different from those caused by cyclic AMP, indicating that different conformational changes are induced by the binding of cyclic GMP. The 19F-n.m.r. spectrum of the complex of [3-F-Tyr]CRP with tubercidin 3',5'-(cyclic)monophosphate (which can activate transcription) showed essentially the same chemical-shift changes as seen for the cyclic AMP complex, indicating that similar conformational changes have been induced by the nucleotide binding. [3-F-Tyr]CRP in the presence of an equimolar amount of the 20 bp self-complementary DNA oligomer 5'-AATGTGAGTTAACTCACATT-3' and excess cyclic AMP gave an 19F-n.m.r. spectrum that was almost identical with that for the [3-F-Tyr]CRP-cyclic AMP complex, indicating that the binding of DNA does not induce significant conformational changes involving the tyrosine residues. Proteolysis of [3-F-Tyr]CRP with chymotrypsin produced a 31 kDa fragment that is a dimer containing the cyclic AMP-binding domain. This fragment contains five of the six tyrosine residues, and its 19F-n.m.r. chemical shifts were essentially the same as those of the intact protein except for one missing signal (signal F): this signal could be assigned to Tyr-206 and shown to be unperturbed by the binding of cyclic nucleotide to the intact [3-F-Tyr]CRP. The similarity of the 19F-n.m.r. chemical shifts in the alpha-fragment and the intact CRP indicates that the alpha-fragment retains the same structure as found in the intact protein.(ABSTRACT TRUNCATED AT 400 WORDS)

Cyclic AMP↗
PubMed1989

Meta-analysis of the relationship between asymptomatic bacteriuria and preterm delivery/low birth weight.

The relationship between asymptomatic bacteriuria and prematurity/low birth weight (LBW) is still a controversial issue, despite many studies. Meta-analysis, a research tool designed to analyze and combine the results of previous studies, may resolve this discrepancy among contradictory results of clinical trials. The purpose of this study was to examine the relationship between asymptomatic bacteriuria and preterm delivery/LBW using meta-analysis. Reports from the literature were classified according to study design into cohort or randomized-treatment control trials. Meta-analysis of cohort studies showed that untreated asymptomatic bacteriuria during pregnancy significantly increased rates of LBW and preterm delivery. Nonbacteriuric patients had only about two-thirds the risk (typical relative risk = 0.65; 95% confidence interval 0.57, 0.74) of LBW and half the risk (typical relative risk = 0.50; 95% confidence interval 0.36, 0.70) of preterm delivery of those with untreated asymptomatic bacteriuria. These reduced risks correspond to a 3.4 (confidence interval 1.8, 5.0) percentage-point difference in LBW and a 3.8 (1.1, 6.4) percentage-point difference in preterm delivery. The analysis of randomized clinical trials showed that antibiotic treatment significantly reduced the risk of LBW (typical relative risk = 0.56; 95% confidence interval 0.43, 0.73), with a substantial reduction of 6.4 (confidence interval 3.3, 9.5) percentage points in the rate of LBW. We conclude that clinical and epidemiologic evidence indicates a strong association between untreated asymptomatic bacteriuria and LBW/preterm delivery and that antibiotic treatment is effective in reducing the occurrence of LBW.

Anti-Bacterial Agents↗
PubMed1985

Ultrasound assessment of the postmature pregnancy.

The use of ultrasound to identify the fetus at risk for postmaturity among postterm pregnancies was evaluated. The ultrasound findings in 85 postterm pregnancies were reviewed. No grade 0 or grade 1 placentas were observed and grade 2 and 3 placentas were found with similar frequency. The incidence of advanced postmaturity was 12.9%. Advanced postmaturity was found with grade 2 and 3 placentas. Oligohydramnios was very common (81.8%) among pregnancies resulting in postmaturity. The neonatal ponderal index was higher with grade 2 placentas than with grade 3 placentas. The presence of immature placentas (grade 0 or 1) is rare after 42 weeks of gestation. Placental grading cannot be used to predict postmaturity.

Adolescent↗
PubMed1985

Sonographically monitored amniocentesis to decrease intraoperative complications.

The rates of intraoperative complications (dry and bloody taps) of two amniocentesis techniques were compared in 1300 patients undergoing second trimester procedures for genetic indications. The sonographically guided technique consisted of the selection of a site for needle insertion with ultrasound, removal of the transducer, and immediate amniocentesis. The sonographically monitored technique consisted of the continuous visualization of the needle during the entire procedure. Six hundred twelve amniocenteses were performed with the sonographically guided technique and 688 with the sonographically monitored technique. There was a statistically significant decrease in the incidence of bloody and dry taps of the first needle insertion (relative risk = 38%, P less than .0001) and also in the number of patients that required multiple needle insertions (relative risk = 42%, P less than .0001) with the sonographically monitored technique.

Amniocentesis↗
PubMed1978

Abortion, adoption, or motherhood: an empirical study of decision-making during pregnancy.

Using matched samples (n = 249) of single, generally young black women, two thirds on welfare and previously pregnant, the study examined why some women decide to deliver while others, with almost identical sociodemographic and prior pregnancy experiences, decide to abort. Women delivering were in significantly longer relationships with partners who had also been less cooperative about contraception. Discussion with significant others occurred more often in decisions to deliver and greater support was received for that option. For many women the abortion decision and, to a lesser extent the decision to deliver, was conflictful, options evenly balanced, and considerable indecision reported. Attitudes about ethical aspects of abortion and knowledge of role models for single parenthood and seeking abortion among friends and relatives also discriminated the two samples. Women who delivered all previous pregnancies found the decision to abort particularly difficult. In this young population 29.2 per cent of women currently delivering had previously aborted; 55.8 per cent of women currently aborting had delivered. During their reproductive life, therefore, almost all women in this population will face the decision whether to abort and many will choose that option. Whether abortion or delivery is chosen will depend upon circumstances surrounding specific pregnancies rather than characteristics of the mother. Adoption is not an option in the pregnancy decision of women in this population.

Abortion, Legal↗
PubMed1977

Patient education by videotape after myocardial infarction: an empirical evaluation.

Patients recovering from myocardial infarction (MI) or other heart diseases at St. Francis Hospital, Hartford, Ct, were educated by videotape or by staff lectures on alternating weeks. Both programs included the following: risk factors for MI, medications, diet, MI symptoms and life style changes. Patients were interviewed before and after the educational program. The MI patients under the age of 60 scored equally well on an informational test irrespective of the type of education program experienced. Older MI patients were significantly more likely to complete the educational program when it was given by videotape; those discontinuing attendance at lectures were less psychologically motivated to participate but were not necessarily more ill. Overall, higher education was the single most significant predictor of superior scores following patient education. Implications for the coronary care ward of the success of videotape in educating MI patients are discussed.

Adult↗
PubMedDate not supplied

Detection of acquired immunodeficiency syndrome (AIDS) retrovirus antibody by lymphadenopathy-associated virus (LAV) enzyme immunoassay in low- and high-risk populations.

Antibody to the acquired immunodeficiency syndrome (AIDS) retrovirus was evaluated by an lymphadenopathy-associated (LAV) enzyme immunosorbent assay (EIA) and compared with the standard human T-cell lymphotropic virus, Type III (HTLV-III) screening test in two groups of people. The first group consisted of those at low risk for AIDS, including 1352 random volunteer donors, 1140 of whom were prospective donors and 212 of whom were retrospective donors, repeatedly reactive by HTLV-III EIA. The second group was composed of those at high risk for AIDS, including 54 hemophiliacs, one of whom had AIDS, seven AIDS-related complex (ARC), and one immune thrombocytopenia (ITP). Of the 1140 prospective donors, one was repeatedly reactive by LAV EIA and four by HTLV-III EIA; none was positive by Western blot. Of the 212 retrospective donors, six were repeatedly reactive by LAV EIA and 212 by HTLV-III EIA; only six (the six LAV EIA positive) were positive by Western blot. Of the 54 hemophiliacs, 46 were repeatedly reactive by both LAV EIA and HTLV-III EIA, and all 46 were positive by Western blot. Both LAV EIA and HTLV-III EIA were positive in all hemophiliacs with AIDS, ARC, and ITP. The marked reduction in HTLV-III EIA repeatedly reactive, Western blot nonreactive samples by the LAV EIA system suggests that this assay may be as sensitive but more specific than the standard HTLV-III EIA in low-risk populations. The strong correlation between the LAV EIA and the Western blot assay further suggests that this assay may provide an efficient screening test for AIDS antibody in the donor population.

Acquired Immunodeficiency Syndrome↗