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Biomedical subjects

M A Sheppard

Publications and source records attributed to M A Sheppard.

At least 19 recordsLinked to original sources
PubMed1998

Fatal firearm-related injury surveillance in Maryland.

CONTEXT: Maryland began a statewide firearm-related injury surveillance system in 1995. The system now focuses on firearm-related deaths; a system to monitor nonfatal injuries is being developed. The system is passive; it accesses, integrates, and analyzes data collected by Maryland's Office of the Chief Medical Examiner, Maryland State Police, and Division of Health Statistics. OBJECTIVE: To evaluate the surveillance system's ability to ascertain cases in the absence of a standard for the true number of cases. DESIGN: Link records of the same firearm-related death captured by the surveillance system's multiple data sources, comparing the rate of false positives and false negatives, and assessing errors in linkage variables. SETTING: Maryland, 1991-1994. PARTICIPANTS: All deaths occurring in the state of Maryland as a result of a firearm-related injury. MAIN OUTCOME MEASURES: Sensitivity and positive predictive value. RESULTS: The system is extremely sensitive, detecting 99.61% of cases, and it has a very high positive predictive value, with 99.87% of the cases identified from medical examiner's office data being confirmed as actual cases. CONCLUSIONS: Maryland's database of information from the medical examiner's office is highly accurate for ascertaining firearm-related deaths that occur in the state. A unique identifier common across data sources would ease record linkage efforts, and improve the system's ability to monitor firearm-related deaths.

Adolescent↗
PubMed1991

A CCl4/CHCl3 interaction study in isolated hepatocytes: non-induced and phenobarbital-pretreated cells.

The purpose of this study was to evaluate an isolated hepatocyte model for predicting the in vivo hepatotoxicity of carbon tetrachloride (CCl4) and chloroform (CHCl3), alone and in combination. Response surface methodology (RSM) was used to analyze and describe the data. The interaction was evaluated for % initial K+ (cell injury) and % LDH leakage (cell death) in non-induced (untreated) and phenobarbital-pretreated suspended hepatocytes. CCl4 and CHCl3 were delivered alone and in combination in dimethyl sulfoxide (DMSO) to suspended hepatocytes. The maximum observed no-effect level (MONEL) for CCl4 in non-induced cells was 1.0 mM (LDH and K+). In induced cells, the MONEL was 0.25 mM (K+) and 0.5 mM (LDH). The MONEL for CHCl3 in non-induced cells was 5.0 mM (LDH and K+) and in induced cells was 0.5 mM (K+) and 1.0 mM (LDH). Phenobarbital pretreatment enhanced the toxicity of both CCl4 and CHCl3, alone and in combination. RSM analysis of the % initial K+ and % LDH for CCl4 and CHCl3 in combination in noninduced and induced cells showed a greater than additive interaction. The isolated hepatocyte model appears to be a promising system for evaluating the toxicity of chemical mixtures and predicting their in vivo effects.

Animals↗
PubMed1990

Interactions of water contaminants. I. Plasma enzyme activity and response surface methodology following gavage administration of CCl4 and CHCl3 or TCE singly and in combination in the rat.

The joint hepatotoxicity of CCl4 and CHCl3 or TCE in male CD rats following simultaneous oral administration has been investigated. Rats with chronic indwelling arterial cannulas were administered a single oral dose of CCl4 and CHCl3 or CCl4 and TCE in 5% Emulphor at doses of 0 to 700 mg/kg. Hepatotoxicity was evaluated by measuring the activity of AST, ALT, and SDH in plasma at 0, 3, 6, 12, 24, 36, 48, and 72 hr postgavage. Response data were analyzed for interaction using response surface methodology. CCl4 alone displayed dose-dependent toxicity. TCE demonstrated little evidence of hepatotoxicity. In combination, both CCl4/CHCl3 and CCl4/TCE displayed a synergistic (supraadditive) response for peak plasma enzyme activity.

Alanine Transaminase↗
PubMed1989

Adolescents' perceptions of cannabis use by their peers: does it have anything to do with behavior?

Young people perceive there are many more people using cannabis than any surveys can document. As part of an education program, students were exposed to survey data to influence their perceptions and in turn to affect their use and intentions to use cannabis in the future. This large study showed that perception has no relationship to use or intentions to use, and that changing perceptions of use is very difficult.

Adolescent↗
PubMed1989

A CCl4/CHCl3 interaction study in isolated hepatocytes: selection of a vehicle.

Emulphor, ethanol, and dimethyl sulfoxide (DMSO) were evaluated as vehicles in studying the toxicity of CCl4 and CHCl3 in isolated hepatocytes. The appropriateness of the vehicle was determined by evaluating the following parameters: solubility of CCl4 and CHCl3 in the vehicle, cell injury (intracellular K+), cell death (LDH leakage), and lack of interaction (protection or enhanced toxicity) with CCl4 and CHCl3. The relative toxicity of the vehicles according to maximum no effect levels (v/v) was: emulphor (0.125%) greater than ethanol (1.0%) greater than DMSO (5.0%). Emulphor at toxic levels was inadequate to dissolve enough CCl4 to evaluate in this system. Ethanol (5.0, 2.5, 1.0, 0.5%) was more toxic than DMSO and interacted with both CCl4 and CHCl3 to enhance toxicity. DMSO (15.0, 5.0, 2.5%) did not significantly alter the toxicity of CCl4 and CHCl3; no interaction. These data suggest that DMSO should be the vehicle for evaluating the toxicity of CCl4 and CHCl3 and their mechanisms of action in the isolated hepatocyte.

Animals↗
PubMed1988

Television as a patient education tool: a review of its effectiveness.

Thirty-three studies of the use of television as a patient-education process are reviewed. While there are many different conditions addressed by the studies and many studies have methodological problems there are consistencies in the results that suggest how this medium has a role to play. Eleven studies randomized subjects and had a control group. All but one reported achieving their objective of knowledge gain, skill training, or behavior change. Video presentation alone was as effective as any other presentation method and was more effective than only written information. Recommendations for the use of television for patient education are included.

Behavior Therapy↗
PubMed1986

Factors associated with cannabis nonuse and cessation of use: between and within survey replications of findings.

Multivariate analyses (Multiple Classification Analyses) of data obtained from repeated surveys (1981 and 1983) of students (grades 7-13) supported the separate consideration of three aspects of cannabis use and nonuse: not trying cannabis; trying and quitting cannabis use; and trying and continuing cannabis use. Marked consistency was found in results obtained from between and within-survey replications. Many variables which exhibited bivariate relationships with cannabis use were not significant when considered multivariately. Few variables were related to both trying vs. continuing cannabis use. Variables which were expected to be related to cannabis use failed to show a significant relationship, most notably those measuring perceived threat of legal consequences, problems at home, problems outside the home, and threats to health. Methodological and substantive, especially educational/prevention, implications are highlighted.

Adolescent↗
PubMed1986

Through the art of children: perceptions of alcohol use and abuse.

Through analysis of children's art, submitted as alcohol education posters, insight was gained as to what children believe to be the effects of alcohol use. More than 5,000 posters were submitted by children in grades one-13 in two poster contests sponsored by the Addiction Research Foundation of Ontario in 1982 and 1984. Most posters were submitted by students in grades four-eight. The most common messages were "Don't Drink" and slogans about drinking and driving. Other messages included use within the family, use with friends, use and sports, use leading to death, physical effects, and solutions to drinking. The message never to drink was prominent, but few posters advocated drinking in moderation.

Adolescent↗
PubMed1985

Peer pressure and drug use--exploding the myth.

"Peer pressure" and "everyone is doing it" have been used as excuses for some drug-taking behavior for too long. We must look harder into reasons for drug use and neither accept these concepts nor teach our young people that this is what is really happening.

Adolescent↗
PubMed1984

Non-use and cessation of cannabis use: neglected foci of drug education.

Analysis of responses from a large sample of students (grades 7-13) indicated that a large proportion of students reported never having tried cannabis, and the majority of those who had tried the drug reported no longer using it. Multivariate analyses, employing Multiple Classification Analysis procedures, identified those variables most strongly associated with initially trying cannabis and with discontinuing its use. These results indicated that some variables had a similar relationship to these two aspects of cannabis use, but other variables were related exclusively either to trying cannabis or to continuing its use. Implications for education and other preventive interventions are highlighted.

Adolescent↗
PubMed1983

Three approaches to alcohol education.

An experimental examination of three approaches to alcohol education compared a cognitive program, a decision-making program and a values-clarification program. The cognitive program was most positively received and was superior in raising levels of knowledge; the values-clarification program was least effective, especially as measured by the program's impact on current and expected alcohol use.

Adolescent↗
PubMed1982

Developmental and generational trends in alcohol, cannabis and tobacco use--a ten year cohort analysis.

Six surveys of drug use (including alcohol) among Ontario (Canada) students (grades 7-13) were conducted between 1968-1979. Cohort analyses identified significant increases in the prevalence and incidence of alcohol and cannabis use for all cohorts with, however, some moderation of cannabis use in recent years within the oldest cohort. Recent tobacco use has shown a reduction in the earlier strong trends towards increased use. Developmental influences on drug use were stronger than generational influences. Implications for preventive intervention are discussed.

Adolescent↗