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Biomedical subjects

R H Gray

Publications and source records attributed to R H Gray.

At least 109 records · Page 6Linked to original sources
PubMed1992

Visual recovery using small dilating eye drops.

It is well established that reduced size dilating eye drops of 1% tropicamide and 10% phenylephrine (micro drops) are effective for clinical purposes. Excellent pupil dilatation (mydriasis) is achieved and pupil constriction does not occur in response to light. In this study, the effect of micro drops of 1% tropicamide on distance and near visual recovery was compared with standard drops in a group of 20 healthy volunteers. For each person studied, one eye was selected at random to be tested first with the standard drop size, and then after a minimum of one week, the same eye was again tested using a drop of the same drug one fifth standard size. An iris photograph, Snellen visual acuity at 6 m, and reading visual acuity was obtained for each test procedure: before drop instillation and at 30 min, 1, 2 and 4 h after drug instillation. Use of the micro drops caused a small but statistically significant improvement in the rate of recovery of distance and near visual acuity. These findings, allied to the known beneficial effects of reduced systemic absorption using micro drops, lend further weight to the argument that mydriasis may be achieved more safely, with fewer side effects, and with earlier return of normal vision when reduced size drops are used. It is hoped that practical micro drop dispensers will be developed.

Adult↗
PubMed1991

In utero exposure to steroid contraceptives and outcome of pregnancy.

A cohort study of women who used steroid contraceptives during pregnancy was conducted in Chiang Mai, northern Thailand, between 1984 and 1987. There were 1,573 pregnancies in which the fetus was exposed to the injectable contraceptive Depo-Provera (The Upjohn Company, Kalamazoo, Michigan) (830 accidental pregnancies and 743 infants conceived before the mother started use of Depo-Provera), 601 accidental pregnancies in women who were using oral contraceptives, and 2,578 planned pregnancies with no steroid exposures (controls). Subjects were followed up for interview, and medical records were traced for birth weight. Women using Depo-Provera had more risk factors for adverse pregnancy outcomes than did the other groups. The adjusted odds ratios for low birth weight were increased for accidental pregnancies with fetal exposure to Depo-Provera (odds ratio (OR) = 1.5, 95% confidence interval (Cl) 1.2-1.9) or oral contraceptives (OR = 1.5, 95% Cl 1.2-2.0). The higher risk of low birth weight among infants exposed in utero to Depo-Provera or oral contraceptives is due in part to self-selection for adverse outcomes among women with unplanned pregnancies. However, among accidental pregnancies with Depo-Provera, the risk of low birth weight was significantly increased when conception was estimated to have occurred within 4 weeks of injection. The odds ratios were 1.9 (95% Cl 1.4-3.2) for injection-to-conception intervals of less than or equal to 4 weeks, 1.5 (95% Cl 0.9-2.3) for intervals of 5-8 weeks, and 1.2 (95% Cl 0.7-1.9) for intervals of greater than or equal to 9 weeks. This trend was highly significant. Thus, the authors conclude that early, high-dose in utero exposures to Depo-Provera may affect fetal growth.

Adult↗
PubMed1991

In utero exposure to steroid contraceptives and survival during infancy.

A cohort study was conducted in Chiang Mai, northern Thailand, in 1,431 children of women who had used the injectable contraceptive Depo-Provera (The Upjohn Company, Kalamazoo, Michigan), 565 children of women who had used oral contraceptives during pregnancy, and a group of 2,307 control infants with no hormonal contraceptive exposures. In follow-up interviews, information was obtained on stillbirths and deaths. Cause of death was ascertained by interview, death certificate, or medical record, and underlying causes of death were ascribed by a panel. The children exposed in utero to Depo-Provera had higher neonatal and infant mortality rates (44.3 and 62.9 per 1,000 live births, respectively) than did the controls (19.8 and 29.1 per 1,000 live births). Mortality in infants exposed in utero to oral contraceptives was intermediate between that in the other two groups. Adjustment by logistic regression showed no significantly increased risk of mortality among infants exposed to oral contraceptives, but the odds ratio for death was significantly increased with Depo-Provera exposures due to accidental pregnancy (odds ratio (OR) = 1.8 (95% confidence interval (Cl) 1.1-3.0) for neonatal deaths; OR = 2.0 (95% Cl 1.3-3.2) for infant deaths). Adjustment for low birth weight reduced the risks, suggesting that low birth weight may act as an intermediate determinant of Depo-Provera-associated mortality. Among the accidental pregnancies with Depo-Provera, there was a relation between shorter injection-to-conception intervals, when maternal blood levels of the drug are high, and an increased risk of mortality. The odds ratios for neonatal mortality were 2.5 (95% Cl 1.1-5.7), 2.1 (95% Cl 1.0-4.6), and 0.9 (95% Cl 0.4-2.4) for injection-to-conception intervals of less than or equal to 4, 5-8, and greater than 9 weeks, respectively. Adjustment for low birth weight reduced these risks. Chi-square tests for trend were highly significant. Similar associations were also observed between Depo-Provera accidental pregnancies and risks of low birth weight. Thus, infants from accidental pregnancies that occur 1-2 months after a 150-mg Depo-Provera injection may be at increased risk for low birth weight and death. However, the attributable risk is low, because such pregnancies are uncommon.

Cause of Death↗
PubMed1991

A case-control study of stillbirths in northeast Brazil.

An institution based case-control study to determine risk factors for stillbirths was conducted in the city of Natal, NE Brazil, where 90% of deliveries take place in health facilities. Two hundred thirty-four singleton stillborn cases were compared to 2555 liveborn singleton control infants of normal birth-weight and gestational age. Information was obtained by postnatal interview and anthropometry, and review of medical records. Univariate analyses revealed a large number of potential risk factors, but after adjustment by logistic regression only six factors remained significantly associated with stillbirth. These were low maternal weight, less than or equal to 50 kg and a history of pregnancy loss, both with odds ratios (OR) of 1.8, inadequate prenatal care defined as less than five visits (OR = 1.9), gestational complications (OR = 14.2), intrapartum complications (OR = 2.0), and congenital malformations (OR = 8.7). There was also an increased risk of stillbirth among older mothers who smoked (OR = 1.4), and evidence of an interaction between smoking and complications of pregnancy. From the public health perspective, the most important factors amenable to intervention were inadequate prenatal care and antenatal or intrapartum complications which were associated with substantial attributable risks (23.8%, 35.2%, and 10.2%, respectively). Thus, in this population, future reductions of the high stillbirth rate (27.2 per 1000 births) will largely depend on the coverage, utilization, and quality of antenatal and intrapartum care.

Adult↗
PubMed1991

Fetal outcome among pregnancies in natural family planning acceptors: an international cohort study.

This international, multicenter, prospective cohort study examines the outcome of pregnancies associated with aging gametes. Comparing pregnancies conceived at or near the peak mucus phase with those occurring before or after the peak provides a means of evaluating the effect of aging gametes. The outcome criteria are (1) rates of spontaneous abortion, (2) low birth weight, and (3) congenital malformations. Preliminary analysis shows a trend toward increased spontaneous abortion with aging gametes in certain subsets (women with prior pregnancy losses) but no effect on birth weight. Too few method failures have yet been studied to make a definitive statement on congenital malformations.

Family Planning Services↗
PubMed1991

Natural family planning and sex selection: fact or fiction?

Determining sex of offspring by timing of intercourse has been a subject of intense interest for the lay public and professional community. This metaaanalysis of couples practicing natural family planning provides an opportunity to evaluate sex ratios in relation to the timing of conception with several parameters, including basal body temperature shift and peak mucus as markers of ovulation. Data from six studies show a statistically significant lower proportion of male births among conceptions that occur during the most fertile time of the cycle.

Body Temperature↗
PubMed1991

Factors related to autonomy and discontinuation of use of natural family planning for women in Liberia and Zambia.

From 1983 to 1988, natural family planning programs were conducted in Liberia and Zambia. In Liberia 1055 and in Zambia 2709 women used natural family planning to avoid pregnancy. These users could become pregnant, discontinue use of the method, or become autonomous users. Women who changed intention did not stop use of natural family planning and were not treated as discontinuations. In a multivariate analysis, client's age, breastfeeding status, employment, urban/rural residence, time of registration in the program, and visit intensity were significantly associated with the outcomes. The most consistent association was that women who entered the programs in the later time periods were more likely to become autonomous users and less likely to discontinue use of the method or to experience an accidental pregnancy.

Adolescent↗
PubMed1991

The influence of drop size on pupil dilatation.

The clinical efficacy of reduced size dilating drops (micro drops), was assessed in 60 patients. For each patient, one eye received the standard 'minim' drop size (26 microliters) while the fellow eye received a micro drop of five microliters. In 20 patients tropicamide 1% was followed after two minutes by phenylephrine 10%, another 20 patients were given tropicamide 1% alone, and for the last 20 patients, 0.5% tropicamide was used. Satisfactory mydriasis was achieved for all pupils except those receiving micro drops of tropicamide 0.5% (25 micrograms tropicamide). Tropicamide 1% in micro drop formulation (50 micrograms tropicamide) gave almost identical mydriasis to that from standard drops (containing 250 micrograms tropicamide). Tropicamide 1% in combination with phenylephrine 10% was superior to tropicamide 1% alone, after standard or micro drop administration. The micro drops used in this study were effective, easy to administer, and caused less patient discomfort.

Drug Administration Schedule↗
PubMed1991

Validation of the diagnosis of childhood morbidity using maternal health interviews.

The diagnosis of childhood illness by maternal health interview surveys is widely used to estimate the prevalence of childhood morbidity in developing countries. To determine the validity of interview-based diagnoses, and to define simple, sensitive and specific diagnostic algorithms, we compared symptoms and signs reported by mothers during structured interviews with physicians' diagnoses for 271 children on the Philippine island of Cebu. The 271 children had 318 physician diagnosed illnesses: 105 acute lower respiratory infections (ALRI), 121 diarrhoeas, 36 measles, 50 upper respiratory infections (URTI), 5 roseola infantums and one milaria rubria. An algorithm for measles (age greater than or equal to 120 days, rash and fever greater than or equal to 3 days and fading of rash) had a sensitivity and specificity of 94%. For ALRI an algorithm of cough, dysponea and fever had a sensitivity of 82%, but specificity was lower in comparison with URTI (58%) than with children who had no respiratory illness (79%). Inclusion of signs of respiratory distress (flaring of nostrils, intercostal retraction) raised the specificity to 83-84%, but reduced sensitivity to 68%. Diagnosis of diarrhoea based on frequent loose or liquid stools had a sensitivity of 95-97% and specificity of 80% in children with or without concomitant non-diarrhoeal illnesses. Addition of questions on numbers of stools (greater than or equal to 6 per day), and no signs of dehydration increased specificity to 95% but reduced the sensitivity to 84-86%. However, specific signs of dehydration were not well reported by the mothers.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1991

Levels and determinants of early neonatal mortality in Natal, northeastern Brazil: results of a surveillance and case-control study.

An institution-based surveillance and nested case-control study was conducted in Natal, Northeastern Brazil to estimate the level and determinants of early neonatal mortality. The early neonatal mortality rate was 25.5 per 1000 live-birth, 75% of early neonatal deaths were premature low birthweight infants, and the mortality rates were 591 and 318 per 1000 respectively, for preterm small for gestational age (PT-SGA) and preterm appropriate for gestational age (PT-AGA) infants. Mortality was 50 per 1000 for term low birthweight, and 8.6 for term normal birthweight AGA infants. In addition to prematurity and low birthweight, the main risk factors associated with early neonatal death were maternal smoking, complications during pregnancy or intrapartum, and inadequate antenatal care. The associations were weaker for prepregnancy factors such as single marital status or low maternal body weight, and no significant associations were observed with socioeconomic status. These findings suggest that in this population, efforts to reduce early neonatal death should focus on improved maternal care and the prevention of prematurity.

Brazil↗
PubMed1991

Peroxisome induction potential and lipid-regulating activity in rats. Quantitative microscopy and chemical structure-activity relationships.

Structurally diverse lipid-regulating agents induce hepatomegaly, hepatic peroxisome proliferation, and hepatocarcinoma in rats by mechanisms not fully understood. Nevertheless the initial hepatic response is a prompt, florid proliferation of peroxisomes. In investigations reported here, changes in the rat hepatic peroxisome compartment were measured by quantitative microscopy to determine chemical structure requirements that relate to peroxisome proliferation and lipid regulation. Aryloxyalkanoic acids plus amide analogs, and thio, benzimidazole, phenylpiperazine, and oxazole derivatives induced peroxisome proliferation and generally decreased plasma triglyceride and total cholesterol levels. These compounds contain an acidic function or are readily metabolized to a chemical with an acidic function. Substitution of the acidic function with an adamantyloxy eliminated peroxisome proliferation and induced contrasting effects on lipid profile, increasing triglycerides and decreasing total cholesterol. A previously unreported, direct correlation emerged between peroxisome proliferation and plasma high-density lipoprotein-cholesterol levels. These effects could not be elicited separately, negating identification of functional groups that could be associated with either activity. Chemical structure and resulting peroxisome proliferation with changes in plasma lipoproteins are therefore closely interrelated in rats.

Amides↗
PubMed1991

Epidemiology of infertility.

Recent infertility literature has focused on the epidemiologic evaluation of diagnostic and therapeutic measures. The predictive value of the postcoital test and the sperm penetration assays has been called into question, particularly for female factor infertility. Several studies have sought better prognostic guidelines for assisted reproductive technologies such as artificial insemination by donor and in vitro fertilization and embryo transfer, as well as more cost-effective screening measures for evaluating infertile couples. Recent epidemiologic investigations have found no adverse effects of infertility therapy on the health of mothers or their babies.

Female↗
PubMed1991

Levels and risk factors for perinatal mortality in Ahmedabad, India.

To estimate levels and determinants of perinatal mortality, we conducted a hospital-based surveillance and case-control study, linked with a population survey, in Ahmedabad, India. The perinatal mortality rate was 79.0 per 1000, and was highest for preterm low-birth-weight babies. The case-control study of 451 stillbirths, 160 early neonatal deaths and 1465 controls showed that poor maternal nutritional status, absence of antenatal care, and complications during labour were independently associated with substantially increased risks of perinatal death. Multivariate analyses indicate that socioeconomic factors largely operate through these proximate factors and do not have an independent effect. Estimates of attributable risk derived from the prevalence of exposures in the population survey suggest that improvements in maternal nutrition and antenatal and intrapartum care could result in marked reductions of perinatal mortality.

Adult↗
PubMed1990

Risk of ovulation during lactation.

60 breastfeeding mothers in Baltimore and 41 in Manila recorded their infant feeding patterns daily, and gave additional information at weekly interviews. Ovarian activity was monitored by assays for hormone metabolites in daily urine samples. On average, women in Baltimore breastfed less often but for longer at each feed than women in Manila, and the mean times until ovulation were 27 and 38 weeks post partum. 41% of first ovulations had luteal phase defects. Anovular first menses were common (45.1%) during the first 6 months post partum but the rate fell greatly thereafter. The risk of ovulation was reduced by a higher frequency of breastfeeds, longer duration of each feed, and less supplementary feeding. During the first 6 months post partum, amenorrhoeic women had low risks of ovulation (below 10%) with partial breastfeeding, and exclusive breastfeeding reduced the risk to 1-5% with either frequent short feeds or infrequent longer feeds. However, if the woman started menstruating before 6 months post partum, or if she continued breastfeeding beyond 6 months, the risk of ovulation rose, and contraception would be needed.

Amenorrhea↗
PubMed1990

Determinants of preterm delivery and intrauterine growth retardation in north-east Brazil.

A case-control study was conducted in Natal, north-east Brazil to determine the risk factors for low birthweight (LBW). Cases were 429 preterm and 422 intrauterine growth retarded (IUGR) singleton infants. Controls were 2555 infants of normal birthweight and gestational age. The prevalence of LBW was 10% (5.1% preterm and 4.9% IUGR). Logistic regression was used to estimate the adjusted odds ratios of LBW, and attributable risk per cent (AR%) was used to estimate the proportion of LBW that might be prevented. The preventable determinants of preterm delivery were births to women less than 20, (AR = 7.1%), low maternal weight less than 50 kg (AR = 20.5%), smoking during pregnancy (AR = 14.6%) and infrequent antenatal visits (AR = 28.1%). Other important determinants of preterm delivery were prior LBW births, gestational illness and vaginal bleeding. The main preventable causes of IUGR were low maternal weight (AR = 17.8%), low maternal education (AR = 11.6%), smoking (AR = 14.8%), and inadequate antenatal care (AR = 11.6%). Other risk factors for IUGR include primiparity, prior LBW births, and illness during gestation. In this population, the focus of short-term preventive programme should be improvement in maternal nutrition, cessation of smoking, reduction of births to women under 20, and improved antenatal care.

Body Weight↗
PubMed1990

Validation of postmortem interviews to ascertain selected causes of death in children.

In developing countries, diagnoses of diseases associated with deaths in children are frequently derived from retrospective maternal interviews. To determine the validity of this methodology, and to define sensitive and specific diagnostic algorithms, we compared symptoms and signs reported by mothers using structured questionnaires, with selected physician diagnoses for 164 deaths among hospitalized children on the Philippine island of Cebu. The 164 decreased children had 256 physician diagnoses of acute lower respiratory infections (ALRI) (100), diarrhoeas (92), measles (48), and neonatal tetanus cases (16). Forty-three per cent of children had multiple illnesses. An algorithm for tetanus (age at death less than or equal to 30 days with convulsion or spasm) was 100% sensitive, but specificity could not be estimated due to the small number of comparison neonatal deaths. An algorithm for measles (age greater than or equal to 120 days, with rash and fever for at least three days) had 98% sensitivity and 90% specificity. Diagnosis of ALRI was more difficult, cough and dyspnoea alone yielding 86% sensitivity but low specificity, whereas prolonged cough and dyspnoea provided 93% specificity but low sensitivity (41%). Diarrhoea diagnoses based on frequent loose or liquid stools had high sensitivity (78-84%) and specificity (79%), irrespective of whether the child died with diarrhoea alone or in combination with other illnesses. However, maternal reports of moderate/severe dehydration had low specificity. We conclude that, in this setting, verbal autopsies can diagnose major illnesses contributing to death in children with acceptable sensitivity and specificity.

Algorithms↗