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Biomedical subjects

D A Dawson

Publications and source records attributed to D A Dawson.

At least 55 records · Page 3Linked to original sources
PubMed1997

Chicken microsatellite markers isolated from libraries enriched for simple tandem repeats.

The total number of microsatellite loci is considered to be at least 10-fold lower in avian species than in mammalian species. Therefore, efficient large-scale cloning of chicken microsatellites, as required for the construction of a high-resolution linkage map, is facilitated by the construction of libraries using an enrichment strategy. In this study, a plasmid library enriched for tandem repeats was constructed from chicken genomic DNA by hybridization selection. Using this technique the proportion of recombinant clones that cross-hybridized to probes containing simple tandem repeats was raised to 16%, compared with < 0.1% in a non-enriched library. Primers were designed from 121 different sequences. Polymerase chain reaction (PCR) analysis of two chicken reference pedigrees enabled 72 loci to be localized within the collaborative chicken genetic map, and at least 30 of the remaining loci have been shown to be informative in these or other crosses.

Animals↗
PubMed1996

Inhibition of tumor necrosis factor-alpha reduces focal cerebral ischemic injury in the spontaneously hypertensive rat.

Tumor necrosis factor-alpha (TNF-alpha) is acutely expressed following focal cerebral ischemia, but its pathophysiological role remains to be extensively characterized. In this study we determined the effect of inhibiting TNF-alpha on the microvascular perfusion impairment and ischemic injury induced by permanent middle cerebral artery occlusion (MCAO). TNF-alpha activity was inhibited with recombinant type I soluble TNF receptor (TNFbp; 1 mg/kg i.v., 0.5 h pre- or post-MCAO). TNFbp significantly attenuated the microvessel perfusion impairment observed in vehicle treated rats, particularly in perifocal/penumbral regions of cortex, and significantly reduced (by 34-38%) the total volume of ischemic injury. These results demonstrate that TNF-alpha contributes to focal ischemic injury and that inhibition of TNF-alpha can confer dramatic neuroprotection. The association of the neuroprotective effect of TNFbp with improved microvascular perfusion suggests that inflammatory and vascular responses to TNF-alpha contribute to its pathological action.

Animals↗
PubMed1996

The relationship between DSM-IV alcohol use disorders and DSM-IV major depression: examination of the primary-secondary distinction in a general population sample.

This study examined the primary-secondary distinction with respect to DSM-IV alcohol use disorders and major depression in a large representative sample of the USA. Primary, secondary and concurrent depressives (i.e. the comorbid groups), respondents classified with major depression only and respondents classified with alcohol use disorders only were compared on a large number of sociodemographic, alcohol-related, depression-related and drug-related variables. Results were at variance with a majority of findings from the treatment literature with regard to familial aggregation of alcohol use disorders and sociodemographic, alcohol and depression profiles. Implications of the results are discussed in terms of the diagnostic and prognostic significance of the primary-secondary distinction.

Adolescent↗
PubMed1996

Developmental toxicity of carboxylic acids to Xenopus embryos: a quantitative structure-activity relationship and computer-automated structure evaluation.

The developmental toxicity for each of 45 carboxylic acids was determined for Xenopus embryos. Acids tested included 12 unbranched, saturated aliphatics, 12 branched, saturated aliphatics, 12 unsaturated aliphatics, and 9 aromatics. Embryos were collected following hormone-induced breeding and exposed to at least eight concentrations of the acid, along with a control. For each concentration, 25 properly developing embryos were exposed to the acid solution for 96 h. Each acid was tested on at least three separate occasions and the data were pooled to calculate 96-h LC50 (lethality), 96-h EC50 (malformation), and DHI (developmental hazard index = 96-h LC50/96-h EC50) values. The endpoint data were subjected to quantitative structure-activity relationship (QSAR) analyse: and computer-automated structure evaluation (CASE). Variation in acid-induced lethality was effectively explained by partitioning and ionizability of the acids, while partitioning alone was somewhat effective in explaining variation for acid-induced malformation. The results indicated that developmental hazard of the acids to Xenopus embryos is primarily dependent on carbon-chain length, with acids containing five carbon atoms in the chain tending to be the most potent. Unsaturation reduced the hazard in comparison with the corresponding unbranched saturated acid. Developmental hazard was highest for 2-position branched compounds with a 5- or 6-C chain, but was reduced for 2-position branched acids with a 3- or 4-C chain. Hazard of the non-2 position branched acids was variable. Valproic (2-propylpentanoic) acid showed the highest developmental hazard with Xenopus, twice that of any other acid tested.

Abnormalities, Drug-Induced↗
PubMed1996

Reducing alcohol-use disorders via decreased consumption: a comparison of population and high-risk strategies.

This study compared three alternative scenarios for effecting a 25% reduction in U.S. alcohol consumption in terms of their respective impacts on the prevalence of alcohol abuse and dependence. The three approaches were (1) an overall 25% reduction in the volume of ethanol intake for all current drinkers, (2) an equivalent absolute reduction taken only among drinkers whose current intake ever exceeds moderate drinking guidelines, and (3) an equivalent reduction taken only among drinkers whose current intake usually exceeds moderate drinking guidelines. The per-occasion cutpoint for moderate consumption was set at the intake level demonstrated to produce psychomotor impairment, and was based on each individual's total body water level. The impact of reducing consumption on the prevalence of alcohol use disorders was estimated by means of a logistic regression model that adjusted for sociodemographic characteristics, family history of alcoholism, and age at first drink, and that took into account interactions between the consumption and other variables. Taking an overall 25% reduction in intake resulted in the same decrease in the prevalence of abuse and dependence (21.7%) as was achieved by taking an equal volume of reduction among only those drinkers whose consumption usually exceeded the moderate drinking cutpoint. Restricting the reduction in consumption to those drinkers whose consumption ever exceeded this cutpoint resulted in a slightly greater reduction in alcohol use disorders, 24.6%.

Adolescent↗
PubMed1996

Gender differences in the probability of alcohol treatment.

Interview data from 7,359 adults 18 years of age and over who met the DSM-IV criteria for alcohol abuse or dependence at some point during their lives revealed that 23.0% of the men and 15.1% of the women ever received treatment for alcohol problems. The median interval from onset of disorder to first treatment was between 2 and 3 years longer for men than women. This difference did not result from women being more likely than men to initiate treatment shortly after onset of an alcohol use disorder, but rather from men being more likely than women to initiate treatment in the period well after onset. Excluding treatment initiated prior to the clinical onset of the disorders or after cessation of drinking, men's and women's cumulative conditional probabilities of having initiated treatment by 30 years after onset of alcohol abuse or dependence were .424 and .356, respectively. Within the first 8 years after onset of abuse or dependence, men's and women's probabilities of initiating treatment were about the same, but men were 13% to 20% more likely to initiate treatment in the period from 8 to 25 years after onset. Use of proportional hazards models to adjust for factors including sociodemographic characteristics, prior consumption, severity of disorder, and comorbid drug use and depression revealed that men's and women's likelihoods of ever having received treatment did not differ for the most severely affected, those with 20 or more symptoms of abuse or dependence. Among those less severely affected, the male-to-female ratio in the likelihood of treatment declined with severity from 1.75 (1 symptom) to 1.24 (15 symptoms).

Adolescent↗
PubMed1996

Temporal drinking patterns and variation in social consequences.

Temporal drinking patterns and their associated social consequences are described for a sample of US adults aged 18 years and over who drank at least 12 drinks in the preceding year and did not restrict their drinking to special occasions (n = 16086). The earliest time of day when these current regular drinkers reported usually drinking was between 6 a.m. and 11 a.m. for 1.2%, between 11 a.m. and 3 p.m. for 7.3%, between 3 p.m. and 6 p.m. for 31.2%, and after 6 p.m. for 60.3%. Less than one-tenth (7.7%) reported any drinking (not necessarily their earliest drinking) between midnight and 6 a. m. Characteristics associated with above-average rates of both early (6 a.m.-3 p.m.) and late-night (midnight-6 a.m.) drinking included male gender, black race, low education and income and heavy quantity of ethanol intake per drinking day. Early drinking was also characteristic of the elderly and daily drinkers. Prior to adjusting for background variables and quantity and frequency of intake, early drinking was associated with a two- to nine-fold increase in the risk of alcohol-related interpersonal problems, hazardous use, job/school problems and legal problems, and late-night drinking was associated with a three- to eight-fold increase in their prevalence. After adjusting for these factors in multiple logistic regression models, early drinking was associated with a 54% increase in the odds of interpersonal problems, a 39% increase in the odds of hazardous use and a 52% increase in the odds of legal problems. The association between early drinking and job/school problems fell just short of statistical significance. After adjusting for other factors, late-night drinking retained a significant association with all of the outcomes except legal problems. The magnitude of its association was greater than that of early drinking but varied substantially (i.e. interacted) with quantity of intake, race, ethnicity and gender.

Adolescent↗
PubMed1996

Acute focal ischemia-induced alterations in MAP2 immunostaining: description of temporal changes and utilization as a marker for volumetric assessment of acute brain injury.

The utility of microtubule-associated protein 2 (MAP2) immunostaining as a marker of acute focal ischemic injury was investigated. Permanent middle cerebral artery occlusion (MCAO) elicited a rapid reduction in MAP2 immunostaining that was visible 1 h post-MCAO and that increased in intensity and area encompassed over time. The ischemic lesion borders were well defined by loss of MAP2 immunostaining, but alterations in staining within the lesion were more heterogeneous. Lesion volume increased significantly from 1 to 4 h post-MCAO (from 63.8 +/- 10.8 to 111.3 +/- 19.0 mm3, mean +/- SD). Thus, MAP2 immunostaining is a sensitive, quantifiable indicator of acute brain injury following focal ischemia.

Analysis of Variance↗
PubMed1996

Medical consequences of alcohol consumption--United States, 1992.

There is plenty of evidence in the alcohol literature that chronic excessive use of alcohol poses a threat to every organ system in the body. At the same time, there is a growing consensus that drinking in moderation protects against cardiovascular disease. This study was based on the most recent national household survey of the United States general population on drinking practices, alcohol use disorders, and their associated disabilities. The prevalence of major alcohol-related diseases were examined across different categories of drinking status. Excess morbidity caused by heavy intake of alcohol was also studied. Results were generally in agreement with the popular belief that light or moderate drinking is beneficial relative to abstention, particularly that moderate alcohol consumption confers a beneficial cardiovascular effect. Our findings also pointed toward the injurious effect of heavy alcohol use. However, results on benefits of drinking must be interpreted with caution.

Adolescent↗
PubMed1996

Correlates of past-year status among treated and untreated persons with former alcohol dependence: United States, 1992.

Past-year status was investigated in a sample of 4,585 adults with prior DSM-IV alcohol dependence. Those who had and had not received treatment for alcohol problems were compared in terms of past-year status and its correlates, to see if the experience of treatment samples would be reflective of the course of alcoholism in the general population. In the past year, 27.8% of the total sample met the criteria for alcohol abuse or dependence, 22.3% were abstinent, and 49.9% were drinkers who did not satisfy the criteria for either abuse or dependence. Persons who had been treated for alcohol problems were about twice as likely to be abstainers as those who had not been treated (38.8% vs. 16.4%), but only about half as likely to fall into the past-year category of drinking without abuse or dependence (28.0% vs. 57.8%). These differentials were of constant magnitude, regardless of the interval since the onset of dependence. For the sample as a whole, persons who had received treatment were slightly more likely than their untreated counterparts to have had alcohol abuse or dependence in the past year (33.2% vs. 25.8%), and this differential increased with the interval since the onset of dependence. The odds of both past-year abstinence and drinking without abuse or dependence were decreased by male gender, Black race, rapidity of the onset of dependence and ethanol intake per drinking day, and were increased by ever having been married and by later ages at onset of dependence. The odds of drinking without abuse or dependence relative to abstinence were increased by college attendance and reduced by the number of dependence symptoms, and having been a daily drinker was associated with increased odds of past-year abstinence. Treatment history modified the associations between past-year status and race, marital and educational status, number of past alcohol problems, and rapidity of onset of dependence and age at onset. These results suggest that treatment studies may not be generalizable to alcoholics who do not seek treatment.

Adolescent↗
PubMed1996

Alcohol and drug use, abuse, and dependence among welfare recipients.

OBJECTIVES: This paper presents national estimates of heavy drinking, drug use, and alcohol and drug abuse and/or dependence among recipients of selected welfare programs. METHODS: Data from the 1992 National Longitudinal Alcohol Epidemiologic Survey were analyzed. RESULTS: The percentages of welfare recipients using, abusing, or dependent on alcohol or drugs were relatively small and consistent with the general US population and those not receiving welfare benefits. CONCLUSIONS: Although a minority of welfare recipients have alcohol or drug problems, substance abuse prevention and treatment services are needed among high-risk subgroups.

Adult↗
PubMed1996

Polymorphonuclear leukocytes and microcirculatory perfusion in acute stroke in the SHR.

In order to determine the effect of depleting circulating polymorphonuclear neutrophils (PMN's) on brain microcirculation and lesion size in an acute stroke model, Spontaneously Hypertensive Rats (SHR) were injected intraperitoneally with either 2 ml RP-3 antineutrophil antibody followed in 4 hours by MCAO (n = 5), 2 ml saline followed in 4 hours by middle cerebral artery occlusion (MCAO) (n = 6), or 2 ml saline followed in 4 hours by sham operation (n = 3). After 4 hours of ischemia or a 4 hour interval (sham-operated animals), microvascular perfusion was assessed by means of an intravascular fluorescent tracer technique: FITC-dextran and Evans blue were injected intravenously 10 seconds and 5 seconds, respectively, before decapitation. Lesion volume was calculated by interpolation from histologic sections cut from 8 predefined stereotactic levels. MCAO with the normal complement of neutrophils led to significant impairment of perfusion in nutrient vessels and a maximal ischemic lesion volume. Depletion of circulating leukocytes by RP-3 significantly attenuated the microvessel perfusion impairment and reduced the volume of ischemic brain injury.

Animals↗
PubMed1995

The neuroprotective efficacy of ebselen (a glutathione peroxidase mimic) on brain damage induced by transient focal cerebral ischaemia in the rat.

The neuroprotective efficacy of the hydroperoxide scavenger ebselen was assessed in a model of transient focal ischaemia that utilises the potent vasoconstrictor peptide endothelin-1 to induce temporary occlusion of the middle cerebral artery (MCA). Pretreatment with ebselen (10 or 30 mg/kg p.o., 40 min pre-MCA occlusion) dose dependently reduced the volume of ischaemic damage assessed 4 h post-endothelin-1 application in the anesthetised rat. The lower dose of ebselen (10 mg/kg) resulted in a non-significant 35% reduction in the total volume of ischaemic damage compared with the vehicle control. In contrast the higher dose of ebselen (30 mg/kg) significantly reduced the volume of ischaemic damage in the cerebral hemisphere and cerebral cortex by 48% and 53%, respectively. The marked reduction in brain damage achieved with ebselen cannot be attributed to drug-induced alterations in blood pressure, body temperature or arterial blood gases since these physiological variables were closely monitored and were not significantly altered by ebselen treatment. Thus ebselen is an effective neuroprotective agent against acute focal ischaemic-reperfusion injury.

Animals↗
PubMed1995

The Alcohol Use Disorder and Associated Disabilities Interview schedule (AUDADIS): reliability of alcohol and drug modules in a general population sample.

Using a representative sample of the general population, the test-retest reliability of the alcohol and drug modules of the Alcohol Use Disorder and Associated Disabilities Interview Schedule (AUDADIS) was examined. The AUDADIS showed good to excellent reliability for measures of alcohol consumption and use of sedatives, tranquilizers, amphetamines, opioids (other than heroin), cannabis and cocaine. Equally good reliability was demonstrated for diagnoses of alcohol, cannabis, cocaine and heroin abuse or harmful use and dependence defined in terms of the International Classification of Diseases-Tenth Revision (ICD-10) and the Diagnostic and Statistical Manual of Mental Disorders-Third Edition-Revised (DSM-III-R) and Fourth Edition (DSM-IV). Results are discussed in terms of the need for future research on the psychometric properties of the AUDADIS in clinical and general population samples.

Adolescent↗
PubMed1995

Subgroup variation in U.S. drinking patterns: results of the 1992 national longitudinal alcohol epidemiologic study.

Data from the 1992 National Longitudinal Alcohol Epidemiologic Study (NLAES) revealed that 44% of U.S. adults 18 years of age and older were current drinkers who had consumed at least 12 drinks in the year preceding the interview. Twenty-two percent were former drinkers, and 34% were lifetime abstainers. These figures represent an 8% decrease in the prevalence of current drinking relative to 1988. The proportion of current drinkers decreased with age, was higher for men than women, increased with education and income, was lower than average among Black and Hispanic adults, was highest among never-married adults and lowest among those who were widowed, was lower in the South than in other regions, and was lower in rural than urban areas. The probabilities of ever having consumed five or more (5+) drinks or having been intoxicated in the past year revealed similar patterns to those already noted, but the probabilities of heavy drinking or intoxication on a weekly or more frequent basis showed no variation by race or ethnicity. Average daily consumption of more than 1 ounce of ethanol differed from the preceding measure of heavy drinking in its variation across population subgroups, declining less sharply with age and exhibiting a U-shaped pattern with respect to income. Examination of the prevalence of heavy drinking among current drinkers rather than within the total population revealed several differences, the most striking reversal being that the probability of heavy drinking decreased with education and income. Multiple logistic regression models predicting the various drinking outcomes indicated that most of the differentials held true after adjusting for intercorrelation among the sociodemographic variables.

Adolescent↗
PubMed1995

What if Americans drank less? The potential effect on the prevalence of alcohol abuse and dependence.

OBJECTIVES: Several advisory committees have recently recommended that alcohol consumption be limited to moderate levels. Moderate drinking has been defined generally as not more than two drinks per day for healthy men and not more than one drink per day for healthy, nonpregnant women. The impact of reducing alcohol consumption to within the recommended guidelines on the prevalence of two serious alcohol-related problems was examined by modeling the relationship between average daily ethanol intake and alcohol abuse and dependence. METHODS: The recommended drinking guidelines, both in their existing form and modified by a measure of impairment, were applied to the observed distribution of consumption derived from a large representative survey of the US general population. RESULTS: The results demonstrated that restricting drinking to the maximum allowable levels under the existing and the modified guidelines would reduce the prevalence of alcohol abuse and dependence by 14.2% and 47.1%, respectively, in the adult US general population. CONCLUSIONS: Implications of these findings are discussed in terms of the validity of the assumptions underlying the models and the nature and direction of future research that would form the basis of newly developed guidelines for safe drinking limits.

Alcohol Drinking↗
PubMed1995

Variation in the association of alcohol consumption with five DSM-IV alcohol problem domains.

Data from a nationally representative sample of the U.S. adult population were used to investigate the association between alcohol consumption and five discrete problem domains included in the DSM-IV formulations for alcohol abuse and dependence. Two dimensions of consumption were considered in the analysis: average daily ethanol intake and the relative frequency of drinking five or more drinks. The sample consisted of 22,102 adults defined as current drinkers. After controlling for various sociodemographic characteristics, family history of alcoholism, and age at onset of drinking, both consumption measures retained significant levels of association within all five problem domains. The magnitudes of the odds ratios at selected levels of consumption were approximately 50% greater for the domains of impaired control, continued drinking despite problems and hazardous drinking than for the domains of tolerance and withdrawal. Moreover, the factors that modified the effect of the consumption measures varied markedly across domains, with age, college education, and race the most consistent modifiers of the effect of alcohol consumption.

Adolescent↗