Search PubMed⌕ Search

Biomedical subjects

G A Richardson

Publications and source records attributed to G A Richardson.

At least 19 recordsLinked to original sources
PubMed2001

Suitability of the Cordis Stabilizer marker guide wire for quantitative coronary angiography calibration: an in vitro and in vivo study.

Catheters usually are used for calibration purposes in quantitative coronary angiography (QCA). The systematic and random errors in these calibration factors (CFs) are dependent on the size and quality of the catheters and limited by out-of-plane magnification (OPM). Theoretically, a guide wire with evenly spaced marker bands would solve many of these potential problems. For this reason, we tested the Cordis Stabilizer marker wire, featuring 10 radiopaque platinum marker bands 15 mm apart, in in vitro and in vivo studies. To assess the effect of foreshortening, wires were positioned in a tube phantom; a centimeter grid was used as the gold standard. Radiographic images were acquired at 5-inch and 7-inch image-intensifier sizes, 512(2) and 1,024(2) matrix sizes and angulations from 0 degrees to 70 degrees in steps of 10 degrees. It was concluded that the relative errors in CFs are less than 7% if the foreshortening angles remain less than 20 degrees. In DICOM images of 15 patients, 65 measurements were taken after calibration on an 8F catheter and on a guide wire positioned in the coronary lesion. In all but two cases, the wire CFs were larger than the catheter CFs (relative difference, 24.7 +/- 19.6%). The measurements were divided into four groups: (I) no apparent OPM or foreshortening (n = 7), (II) only OPM (n = 4), (III) only foreshortening (n = 10), and (IV) the combination of both (n = 44). In group I (no OPM or foreshortening) the QCA results were similar using the guide wire or catheter as the calibration device (relative CF difference, 2.9% only). In group III the diameters were overestimated using the guide wire (obstruction diameter difference, 0.22 +/- 0.11 mm; reference diameter difference, 0.35 +/- 0.06 mm). For only OPM (group II) and the combination of OPM and foreshortening (group IV), the lesion length was underestimated on average by 2.4 mm using the catheter instead of the guide wire. In conclusion, if accurate assessment of the lesion length is important, the marker wire should be used for calibration purposes. For vessel diameter measurements, the conventional catheter calibration approach is the method of choice.

Angiography, Digital Subtraction↗
PubMed2000

Effects of prenatal cocaine/crack and other drug exposure on electroencephalographic sleep studies at birth and one year.

OBJECTIVE: Little is known about the neurophysiologic effects of prenatal cocaine/crack use. The aim of this study, designed to overcome methodologic limitations of previous research, was to investigate the effects of prenatal cocaine use on electroencephalographic (EEG) sleep patterns, a marker of central nervous system development. METHODS: In a longitudinal study of prenatal cocaine/crack exposure, women were interviewed at the end of each trimester about cocaine, crack, alcohol, tobacco, marijuana, and other drug use. Two-hour paper- and computer-generated EEG sleep recordings were obtained on a sample of the full-term infants on the second day of life and at 1 year postpartum. Eligible newborns were full-term, had received no general anesthesia, and had a 5-minute Apgar score >5. All infants whose mothers used one or more lines of cocaine during their first trimester or any crack (n = 37) were selected. A comparison group was chosen randomly from the group of women who did not use cocaine or crack during their pregnancy (n = 34). RESULTS: Women who used cocaine/crack during the first trimester were older, less educated, less likely to be working, and used more tobacco, alcohol, marijuana, and other illicit drugs than women who did not use cocaine/crack during the first trimester. There were no differences in infant birth weight, length, head circumference, or gestational age between the two exposure groups. After controlling for the significant covariates, prenatal cocaine exposure was associated with less well developed spectral correlations between homologous brain regions at birth, and with lower spectral EEG power values at 1 year of age. Prenatal alcohol, marijuana, and tobacco use were found to affect state regulation and cortical activities. CONCLUSIONS: These results indicate that the neurotoxic effects of prenatal cocaine/crack use can be detected with quantitative EEG measures.

Adult↗
PubMed2000

Effects of prenatal tobacco exposure on preschoolers' behavior.

This is a longitudinal study of the relationship between prenatal tobacco exposure and the development of behavior problems in 672 children at the age of 3 years. Women from a prenatal clinic were interviewed about substance use at the end of each trimester of their pregnancy and at 3 years postpartum. Children were assessed at the age of 3 years with maternal ratings of behavior problems, activity, and attention. The prevalence of tobacco use was high in this cohort; 54.3% and 52.3% of the women smoked tobacco in the first and third trimesters of pregnancy, respectively. At 3 years postpartum, 61.6% of the women were smokers. There were significant effects of prenatal tobacco exposure on the children's behavior at age 3 years. Increases in scores on the Oppositional Behavior, Immaturity, Emotional Instability, Physical Aggression, and Activity scales and in the total score on the Toddler Behavior Checklist (TBC) were significantly associated with prenatal tobacco exposure. Smoking one pack of tobacco cigarettes per day during the third trimester of pregnancy was associated with an increase of 6 points in the total problem behavior score. Among the subscales of the TBC, tobacco exposure had the largest effect on oppositional behavior. Impulsivity and peer problems were associated with both prenatal and current tobacco exposure. Only current tobacco exposure predicted attention problems. Prenatal tobacco exposure had a significant negative effect on the development of behavior problems among preschoolers.

Adolescent↗
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↗
PubMed1999

Prenatal alcohol use and offspring size at 10 years of age.

The Maternal Health Practices and Child Development Project is a longitudinal study of the effects of prenatal exposure to alcohol and other substances. Women were selected from a prenatal clinic and interviewed at the 4th and 7th months of pregnancy. Their offspring were examined at delivery, at 8 and 18 months, and at 3, 6, and 10 years. This report examined 610 offspring, at age 10, who were exposed prenatally to alcohol. Most alcohol use in this low-income cohort was light to moderate, although the entire spectrum of alcohol use is represented. The weight, length, head circumference, and skinfold thickness of the offspring were measured. At each assessment phase, we found a significant association between size and prenatal exposure to alcohol. At age 10, the children who were prenatally exposed to alcohol continued to be significantly smaller in weight, height, head circumference, and skinfold thickness. These results indicate that prenatal alcohol exposure has a long-term impact on offspring growth.

Alcohol Drinking↗
PubMed1998

Prenatal cocaine exposure. A longitudinal study of development.

The current study examines the effect of prenatal cocaine use on physical, cognitive, and behavioral development at birth, 1, 3, and 7 years, controlling for other factors that affect child development. Women who used cocaine during pregnancy were more likely to be single and to use alcohol, marijuana, and tobacco than were women who did not use cocaine. Prenatal cocaine use was associated with reduced gestational age, but not with birth weight, length, or head circumference. Neonatal neurobehavioral assessments were affected by prenatal cocaine exposure. Growth at 1 year was not affected by prenatal cocaine use. At 3 years, prenatal cocaine use was a significant predictor of head circumference and of the composite score on the Stanford-Binet Intelligence Scale (4th edition). Prenatal cocaine use was also associated with temperamental differences at 1 and 3 years and with behavior problems at 3 years. These findings represent a pattern of central nervous system effects, related to prenatal cocaine exposure, which is predicted by the teratologic model.

Adult↗
PubMed1998

Effects of prenatal substance exposure: altered maturation of visual evoked potentials.

We investigated the effects of prenatal substance use on visual evoked potentials (VEPs). Seventy-four children were tested at birth and 1 month of age with binocular flash VEPs and at 4, 8, and 18 months of age with binocular pattern VEPs. Regressions were run by trimester to assess the independent effects of substance exposure. Variables included in the regression model were alcohol, marijuana, tobacco, other drug use for each trimester, maternal age, education, income, race, marital status, infant sex, birthweight, and Dubowitz score. Changes in specific components of the binocular VEP were both substance- and trimester-specific. First trimester alcohol use was associated with prolonged P1 wave latencies at 1 month of age. Prolonged P1 wave latencies at birth and 18 months were associated with tobacco use during each of the three trimesters, at 1 and 18 months with third trimester marijuana use, and at 1 and 18 months with first trimester other illicit drug use. Although these women were moderate substance users during pregnancy, their offspring exhibited maturational changes in components of the VEP in the absence of neonatal behavioral disturbances.

Aging↗
PubMed1996

Prenatal exposure to alcohol and marijuana: effects on motor development of preschool children.

Gross motor development of preschool children prenatally exposed to alcohol and marijuana was assessed as part of a longitudinal study. Most mothers in the study were light to moderate users and discontinued or decreased use of alcohol and marijuana after the first trimester of pregnancy. The women were of lower socioeconomic status, half of the sample was African-American, and most were single. Gross motor development was evaluated with balance and ball-handling items at 3 years. Balance items included walking on a line, walking on a balance beam, standing on one foot, standing on tiptoes, and stair climbing and descent. Ball-handling items included catching, throwing, and kicking a ball. Refusal to perform items was also recorded. Prenatal alcohol and marijuana exposure did not negatively affect gross motor development. The composite score on the Stanford-Binet Intelligence Scale, age at assessment, gender, and examiner were significant predictors of gross motor performance and of refusal to participate in the balance items. The ponderal index, number of siblings, current income, examiner, current maternal use of tranquilizers, and first trimester exposure to amphetamines were also significant predictors of balance skills. Gender and number of hospitalizations predicted refusal to participate in balance items, whereas hearing and vision problems predicted refusal on ball-handling items. The components of timing, speed, and fine motor control have not been addressed in this study, and therefore it is premature to conclude that there is no impact of prenatal substance use on motor development.

Child, Preschool↗
PubMed1996

Prenatal alcohol exposure and academic achievement at age six: a nonlinear fit.

This is a report on the effects of prenatal alcohol exposure on the academic achievement of children at 6 years of age. In this longitudinal study, women were interviewed at the end of each trimester of pregnancy, at delivery, and at 8, 18, 36, and 72 months postpartum. The women were of lower socioeconomic status, high school-educated, and moderate users of alcohol. The offspring received age-appropriate physical and developmental assessments at each follow-up. Linear regression and nonlinear curve fitting were used to investigate the nature and shape of the relationship between prenatal alcohol exposure and achievement. In addition, the role of child IQ in this relationship was explored. Alcohol exposure during the second trimester predicted deficits in each of the three subtests of the Wide Range Achievement Test-Revised (WRAT-R): reading, spelling, and arithmetic. The relationship was partially reduced by the addition of IQ to the model, but prenatal alcohol exposure still predicted significant deficits in achievement, even after controlling for IQ. Tests for the shape of the relationship demonstrated that the effect of prenatal exposure on the arithmetic subtest of the WRAT-R was a linear or dose-response relationship. By contrast, the relationships between prenatal alcohol exposure and performance on the spelling and reading subtests of the WRAT-R were better modeled as threshold effects. The thresholds for both were approximately 1 drink/day in the second trimester.

Achievement↗
PubMed1995

Cost effectiveness of antenatal screening for cystic fibrosis.

OBJECTIVE: To estimate the cost effectiveness of different antenatal screening programmes for cystic fibrosis. SETTING: Antenatal clinics and general practices in the United Kingdom. DESIGN: Four components of the screening process were identified: information giving, DNA testing, genetic counselling, and prenatal diagnosis. The component costs were derived from the literature and from a pilot screening study in Yorkshire. The cost of a given screening programme was then obtained by summing the components according to the specific screening strategy adopted (sequential and couple), the proportion of carriers detected by the DNA test, and the uptake of screening. Baseline assumptions were made about the proportion with missing information on carrier status from previous pregnancies (20%), the proportion changing partners between pregnancies (20%), and the uptake of prenatal diagnosis (100%). Sensitivity analysis was performed by varying these assumptions. MAIN OUTCOME MEASURE: Cost per affected pregnancy detected. RESULTS: Under the baseline assumptions sequential screening costs between pounds 40,000 and pounds 90,000 per affected pregnancy detected, depending on the carrier detection rate and uptake. Couple screening was more expensive, ranging from pounds 46,000 to pounds 104,000. From the sensitivity analysis a 10% change in the assumed proportion with missing information from a previous pregnancy alters the cost by pounds 4000; a 10% change in the proportion with new partners has a similar effect but only for couple screening; and cost will change directly in proportion to the uptake of prenatal diagnosis. CONCLUSIONS: While economic analysis cannot determine screening policy, the paper provides the NHS with the information on cost effectiveness needed to inform decisions on the introduction of a screening service for cystic fibrosis.

Cost-Benefit Analysis↗
PubMed1994

Detrimental effects of prenatal cocaine exposure: illusion or reality?

OBJECTIVE: The primary purpose of this study is to investigate the impact of prenatal cocaine exposure, while controlling for other factors that influence infant outcome. METHOD: These preliminary data are from an ongoing prospective study of prenatal cocaine and/or crack exposure. Detailed information is collected about the use of cocaine, crack, alcohol, tobacco, marijuana, and other drugs during each trimester of pregnancy. RESULTS: Women who use cocaine and/or crack during pregnancy differ from those who do not. The women who use cocaine are older, more likely to be black, and less likely to be married. They also use more tobacco, alcohol, and marijuana during pregnancy than do nonusers of cocaine. When these differences between the exposure groups are controlled, preliminary analyses indicate there is no significant effect of prenatal cocaine use on infant growth and morphology. CONCLUSIONS: Future research needs to address the effects of prenatal cocaine and/or crack exposure on central nervous system development and on the long-term development of exposed offspring.

Adolescent↗
PubMed1994

Alcohol, marijuana, and tobacco: effects of prenatal exposure on offspring growth and morphology at age six.

Little is known about the long-term effects of prenatal exposure to alcohol. There are even fewer reports on the longitudinal effects of exposure to either marijuana or tobacco during pregnancy. This study is on the 6-year follow-up of 668 children enrolled in the Maternal Health Practices and Child Development Project. Mothers were interviewed at the 4th and 7th months of pregnancy, and mothers and children were evaluated at delivery, 8, and 18 months, and 3 and 6 years postpartum. At 6 years of age, children who were exposed to alcohol prenatally were significantly smaller in weight, height, head circumference, and palpebral fissure width. These effects on size were mediated by the effect of prenatal alcohol exposure on the offspring at 8 months. Prenatal alcohol exposure was also significantly associated with maternal reports of the child's appetite at 6 years. There were no effects of prenatal marijuana or tobacco exposure on growth when the children were age 6. There were also no significant relationships between prenatal exposure to alcohol, marijuana, or tobacco and the rate of morphologic anomalies, including the features of the fetal alcohol syndrome.

Alcohol Drinking↗
PubMed1994

A comparison of prenatal drinking in two recent samples of adolescents and adults.

The drinking patterns of 124 pregnant teenagers are described and compared with those of 267 pregnant adults attending the same prenatal clinic in Pittsburgh. Adults had a significantly higher average daily volume of alcohol prior to pregnancy than adolescents, but that higher level was no longer significant during pregnancy. However, the rate of binge drinking during the first trimester was higher in the teenage sample than in the adult sample. Rates of binge drinking and heavy drinking were highest among the white teenage group. Use of marijuana and cocaine/crack decreased precipitously during pregnancy for both teenagers and adults. Tobacco use also decreased among the adults, but increased from 56% to 71% during pregnancy in the teenage sample. Based on our findings, patterns of drinking among adult pregnant women do not generalize to pregnant adolescents. Offspring of white adolescents, in particular, may be at higher risk for intermittent high peak alcohol exposure farther into the pregnancy than are offspring of older women.

Adolescent↗
PubMed1993

The epidemiology of alcohol, marijuana, and cocaine use among women of childbearing age and pregnant women.

Although most women report alcohol use, women generally are light drinkers. Those who drink and drink heavily are more likely to be young, white, single, to have a higher education and income, and to be employed outside the home. However, women who drink during pregnancy, and particularly, those who continue to drink through the third trimester are different. They are older, more likely to be black, and they have higher rates of illicit drug use, less education, and lower social status. Marijuana and cocaine are used less frequently. However, women of childbearing age have the highest rates of use for both these drugs. Women who use marijuana during pregnancy are more often black, unmarried, and of lower social class. Cocaine users tend to be black, older, unmarried, and also of lower socioeconomic status. Both groups more frequently use other illicit drugs and, in general, receive less prenatal care. Therefore, for alcohol, marijuana, and cocaine, the highest rates of use are found among women of childbearing age. The women most likely to use substances during pregnancy are women who also have other characteristics that are, in themselves, significant risk factors for poor pregnancy outcome. These covariates must be considered in the evaluation of the effects of prenatal substance use.

Adolescent↗
PubMed1993

The impact of prenatal marijuana and cocaine use on the infant and child.

The prevalence of cocaine use by pregnant women has been estimated by various researchers to range from 8-17%. Women who use cocaine during pregnancy are usually older and black and use more of other drugs. The effects of prenatal cocaine use on a variety of outcomes have not been substantiated. For each outcome discussed, there are as many reports of no effects as there are reports of detrimental effects. The studies that indicate that there are no effects of exposure are generally more sound methodologically. It is also possible that there are additional investigations of prenatal cocaine use that have not been published because of the hesitancy to publish reports in which no effects have been found. The findings regarding obstetric complications are equivocal. Although some investigators have demonstrated significant effects of cocaine use during pregnancy, particularly on abruptio placentae, many of these relationships disappear when factors such as prenatal care and polydrug use are assessed. The same pattern can be noted for the effects of prenatal cocaine exposure on gestational age, growth, and morphology. Significant effects of prenatal cocaine use on these outcomes have been reported by some investigators. However, these results are found generally in studies where poly-drug-cocaine users are compared with non-drug-using women. Such comparisons do not control adequately for other factors in the lifestyles of the cocaine-using woman. There are few significant differences when the offspring of cocaine-using women are compared with those of women who use other drugs. It is difficult to evaluate the effects of prenatal cocaine use on either neonatal neurobehavioral outcomes or on long-term growth and development because of the insufficient number of studies and the equivocal findings. Longitudinal studies are needed to disentangle the effects of cocaine use from the effects of the lack of prenatal care, polydrug use, and the increased risks associated with a drug-using life style.

Child↗
PubMed1993

Drinking patterns and correlates of drinking among pregnant teenagers.

Many adolescents drink, and the rate of teenage pregnancy is increasing, yet the effect of drinking among pregnant teenagers has received little attention. We present a description of the drinking patterns of 124 pregnant teenagers attending a prenatal clinic in Pittsburgh. Sixty-nine percent of the women were African-American, and the average age was 16 years (range 13-18 years). Eighty-two percent drank the year before pregnancy, while 54%, 19%, and 15% drank during the first, second, and third trimesters, respectively. All substance use decreased between the first and third trimesters, with the exception of tobacco, which rose significantly. Binge drinking (5+ drinks/occasion) occurred in 31% of the sample before pregnancy, rose to 35% in the first trimester, and then fell precipitously. Binge drinkers during pregnancy were more likely to be white and heavier users of tobacco, marijuana, and cocaine. Binge drinkers experienced alcohol and tobacco use and sexual intercourse earlier than nonbinge drinkers. Binge drinking in the first trimester may be considered a risk factor for infants of adolescents.

Adolescent↗
PubMed1992

Sleep architecture and continuity measures of neonates with chronic lung disease.

Electroencephalographic (EEG) sleep studies of 25 preterm neonates with chronic lung disease (CLD) corrected to a fullterm postconceptional age were compared with recordings from two groups of neonates without CLD: a fullterm appropriate for gestational age group (9 patients) and a preterm group studied at a corrected term postconceptional age (15 patients). Electrographic/polygraphic studies were obtained using 21-channel EEG recordings. Scores were tabulated based on minute-by-minute visual analyses of sleep state, number and duration of arousals, body movements and rapid eye movements (REM). A significant reduction in the percentage of active sleep was noted in the CLD group compared to both control groups (31.15% vs. 47.01% and 52.9%, respectively). The mean percentage of indeterminate sleep was significantly increased in the study group as compared to both control groups (31.23% vs. 15.18% and 11.5%). In addition, significant differences were noted between the CLD group and the healthy preterm control group with respect to the number (0.29/minute vs. 0.13/minute) and duration (4.8 seconds vs. 2.94 seconds) of arousals as well as the total number of body movements (1.57/minute vs. 0.74/minute). These data suggest that neurophysiological organization of the immature brain, as reflected in neonatal sleep architecture and continuity measures, is adversely affected in neonates with CLD. EEG sleep architecture and continuity measures may be helpful in predicting the longitudinal outcome of infants with CLD as this group is at risk for adverse neurodevelopmental outcome.

Cerebral Cortex↗