Trends and subgroup differences in transportation-related injury risk and safety behaviors among high school students, 1991-1997.

PURPOSE: To examine national trends in transportation-related injury risk and safety behaviors among U.S. high school students. METHODS: To examine secular trends in riding with a driver who had been drinking, driving after drinking, and using seat belts, bicycle helmets, and motorcycle helmets, we used logistic regression to analyze data from national Youth Risk Behavior Surveys (YRBS) conducted in 1991, 1993, 1995, and 1997. The YRBS is a self-administered, anonymous survey that uses a national probability sample of U.S. students in public and private schools from grades 9-12 (N = 55,734 for all years combined). RESULTS: The percentages of students who rode with a driver who had been drinking (36.6% in 1997), drove after drinking alcohol (16.9% in 1997), always wore seat belts (33.2% in 1997), and always wore a motorcycle helmet when riding a motorcycle (45.0% in 1997) remained stable between 1991 and 1997. From 1991 to 1997, the percentage of bicycle riders who always wore a helmet when bicycling showed a small but statistically significant increase (1.1% in 1991 to 3.8% in 1997), but helmet use remained low. CONCLUSION: Many young people place themselves at unnecessary risk for motor vehicle- and bicycle-related crash injuries and fatalities. Improved motor vehicle- and bicycle-related injury prevention strategies are needed that specifically target adolescents.

Relationship between cigarette, smokeless tobacco, and cigar use, and other health risk behaviors among U.S. high school students.

This study examined relationships between tobacco use and use of other substances, intentional injury risk behaviors, and sexual risk behaviors among US high school students. Data about tobacco use and other health risk behaviors were analyzed from the 1997 national Youth Risk Behavior Survey implemented by the Centers for Disease Control and Prevention. One-fourth of students (24%) reported current use of a single tobacco product (i.e., cigarettes, smokeless tobacco, or cigars during the 30 days preceding the survey), and 19.5% reported currently using more than one tobacco product. Generally, students who reported current tobacco use also reported engaging in other substance use, intentional injury risk behaviors, and sexual risk behaviors. For many risk behaviors, these results were especially pronounced among students who reported using two or all three tobacco products. Programs designed to prevent tobacco use should consider that such use often occurs concomitantly with other health risk behaviors.

Use of birth control pills, condoms, and withdrawal among U.S. high school students.

PURPOSE: To examine the use of contraception at last sexual intercourse among currently sexually active adolescents. METHODS: We analyzed data from national school-based Youth Risk Behavior Surveys (YRBS) conducted in 1991, 1993, 1995, and 1997. The YRBS is a self-administered, anonymous survey which uses a national probability sample of U.S. students in public and private schools from grades 9 through 12. RESULTS: From 1991 to 1997, condom use significantly increased (from 46% to 57%), birth control pill use decreased (from 21% to 17%), and use of withdrawal significantly decreased (from 18% to 13%). In 1997, although more students were using condoms, 13% reported using withdrawal and 15% reported using no method to prevent pregnancy at last sexual intercourse. In 1997, condom use among females was significantly lower in the 9th grade than in the 12th grade (p <.001), whereas birth control pill use was higher (p <.001) and use of withdrawal remained stable. Among males, condom use and withdrawal use remained stable from 9th to 12th grade, whereas birth control pill use by their partner increased (p <.001). CONCLUSIONS: Inadequate contraceptive use among sexually active adolescents continues to be a major public health problem in the United States. For young people who will not remain sexually abstinent, families, health care providers, schools, and other influential societal institutions should promote the correct and continued use of condoms as essential protection against sexually transmitted diseases and human immunodeficiency virus infection.

Suicide ideation among US college students. Associations with other injury risk behaviors.

Suicide, the endpoint of a continuum that begins with suicide ideation, is the third leading cause of death among the US college-aged population. The first and second leading causes of death among this age group, unintentional injury and homicide, may also be linked to suicide ideation. We used data from the National College Health Risk Behavior Survey to examine the association between suicide ideation and injury-related behaviors among 18- to 24-year-old college students. Students who reported suicide ideation were significantly more likely than students who did not report considering suicide to carry a weapon, engage in a physical fight, boat or swim after drinking alcohol, ride with a driver who had been drinking alcohol, drive after drinking alcohol, and rarely or never used seat belts. Given this clustering of injury-related risk behaviors, college prevention programs should aim to reduce risks for injuries comprehensively, rather than addressing each risk behavior separately.

Initiation of cigarette smoking and subsequent smoking behavior among U.S. high school students.

BACKGROUND: Most adult smokers report trying their first cigarette before age 18 years. Understanding the impact of smoking initiation at young ages may help public health policy makers and practitioners improve strategies to prevent or delay adolescent cigarette smoking. METHODS: This paper examined age of initiation of cigarette smoking and subsequent patterns of smoking among U.S. high school students 16 years of age and older (N = 13,858). We used data from the 1991-1997 national Youth Risk Behavior Surveys, conducted by the Centers for Disease Control and Prevention. RESULTS: The majority of students 16 years of age and older (60.4%) reported ever having smoked a whole cigarette, and 11.1% initiated smoking at age 10 years or younger. Age of smoking initiation was significantly related to current frequent smoking, daily smoking, and whether students had ever smoked daily. A younger age of smoking initiation was associated with smoking more cigarettes per day than was initiating at an older age. CONCLUSIONS: Delaying the onset of smoking may affect the likelihood of becoming addicted to nicotine and smoking heavily. For students who are already addicted to nicotine, smoking cessation programs are needed.

Bioreductive activation of a series of indolequinones by human DT-diaphorase: structure-activity relationships.

A series of indolequinones including derivatives of EO9 bearing various functional groups and related indole-2-carboxamides have been studied with a view to identifying molecular features which confer substrate specificity for purified human NAD(P)H:quinone oxidoreductase (DT-diaphorase), bioreductive activation to DNA-damaging species, and selectivity for DT-diaphorase-rich cells in vitro. A broad spectrum of substrate specificity exists, but minor changes to the indolequinone nucleus have a significant effect upon substrate specificity. Modifications at the 2-position are favorable in terms of substrate specificity as these positions are located at the binding site entrance as determined by molecular modeling studies. In contrast, substitutions at the (indol-3-yl)methyl position with bulky leaving groups or a group containing a chlorine atom result in compounds which are poor substrates, some of which inactivate DT-diaphorase. Modeling studies demonstrate that these groups sit close to the mechanistically important amino acids Tyr 156 and His 162 possibly resulting in either alkylation within the active site or disruption of charge-relay mechanisms. An aziridinyl group at the 5-position is essential for potency and selectivity to DT-diaphorase-rich cells under aerobic conditions. The most efficient substrates induced qualitatively greater single-strand DNA breaks in cell-free assays via a redox mechanism involving the production of hydrogen peroxide (catalase inhibitable). This damage is unlikely to form a major part of their mechanism of action in cells since potency does not correlate with extent of DNA damage. In terms of hypoxia selectivity, modifications at the 3-position generate compounds which are poor substrates for DT-diaphorase but have high hypoxic cytotoxicity ratios.

Smoking initiation and smoking patterns among US college students.

The ages at which 18- to 24-year-old college students started smoking and its relationship to subsequent smoking were explored, using data from the 1995 National College Health Risk Behavior Survey. Most students (70%) had tried smoking; among those who had tried, 42% were current smokers, 19% were current frequent smokers, and 13% were current daily smokers. The majority (81%) who had ever smoked daily began doing so at age 18 years or younger, and 19% began smoking daily at age 19 years or older. Women were as likely as men to report ever having smoked a whole cigarette or ever having smoked daily. Most students (82%) who had ever smoked daily had tried to quit, but 3 in 4 were still smokers. Policies and programs designed to prevent the initiation of smoking and to help smokers quit are needed at both the high school and the college levels to reduce the proportion of young adults who smoke cigarettes.

Unsafe motor vehicle practices among substance-using college students.

This study examines the relationship between substance use and behaviors that increase the risk for motor vehicle crashes and crash-related injuries. The investigation uses National College Health Risk Behavior Survey data collected in 1995 by the Centers for Disease Control and Prevention. These data are representative of 2- and 4-year undergraduate college students in private and public colleges and universities in the United States. Smokers, episodic heavy drinkers, marijuana users and users of illegal drugs in combination with alcohol were significantly more likely to drive after drinking alcohol and ride with a driver who had been drinking alcohol and significantly less likely to wear safety belts while driving or while riding in a car as a passenger. This study indicates that college students who are substance users are more likely to behave in a manner which increases their risk for motor vehicle crashes and motor vehicle crash injuries.

Bioreductively-activated prodrugs for targeting hypoxic tissues: elimination of aspirin from 2-nitroimidazole derivatives.

2-Nitroimidazoles were synthesised substituted with aspirin or salicylic acid, as leaving groups linked through the (imidazol-5-yl)methyl position. Activation of aqueous solutions by CO2*- (a model one-electron reductant) resulted in release of aspirin or salicylate, probably via the 2-hydroxyaminoimidazole. The analogous 2-nitroimidazole with bromide as leaving group eliminated bromide in < 1 ms via the radical-anion.

Prodrugs for targeting hypoxic tissues: regiospecific elimination of aspirin from reduced indolequinones.

A series of regioisomeric derivatives of a 1-methylindole-4,7-dione were synthesised, substituted with a 2-acetoxybenzoate leaving group linked through the (indol-2-yl)methyl or (indol-3-yl)methyl (or propenyl) positions. Reductive elimination of the leaving group occurred from the (indol-3-yl)methyl derivatives but not the 2-substituted regioisomers, indicating that only the C-3 position may be utilised in bioreductively-activated drug delivery, which was demonstrated with an aspirin prodrug.