Extending the use of Earth's Field NMR using Bayesian methodology: application to particle sizing.

There is currently much interest in extending the use of low-field magnetic resonance measurements and in particular, to obtain spatial information from these data. Here, we demonstrate the application of a Bayesian magnetic resonance approach for the sizing of objects using low magnetic field measurement technology, where there is insufficient signal-to-noise to allow a conventional imaging approach for structural characterisation. The method is illustrated in application to the sizing of spheres, in this case of radius 9.5mm, using an Earth's Field Nuclear Magnetic Resonance (EFNMR) spectrometer with pre-polarisation. Numerical simulations of the measurement at different signal-to-noise ratios and implementation of different k-space sampling schemes are considered to identify the optimal experimental protocol. In this example, the determination of sphere radius is found to be accurate to ±1mm. We confirm that the posterior distribution provides an accurate estimate of the uncertainty in the measurement.

Noninvasive recovery and detection of possum Trichosurus vulpecula DNA from bitten bait interference devices (WaxTags).

The brushtail possum is a major agricultural and ecological pest in New Zealand. A novel noninvasive DNA sampling tool for detecting its presence (WaxTags, or WT) was tested. DNA was recovered from saliva left on WT, and two lengths (407 bp and 648 bp) of the cytochrome c oxidase I (COI) barcoding region were amplified by polymerase chain reaction (PCR). PCR products were considered (+) when a DNA band was clearly visible by electrophoresis. Different factors that might affect PCR (+) were investigated with captive possums: (i) both extraction protocols of the QIAGEN DNeasy Blood and Tissue Kit, (ii) effect of an overnight or longer delay of up to 3 weeks before DNA extraction on both COI amplicons, and (iii) effect of the individual, order and magnitude of the bite. Extraction protocols were not significantly different. The effect of the overnight delay was not significant, and amplification of the short amplicon was significantly higher (100%) than for the long fragment (48%). After a two or 3-week delay, the short amplicon had 94% and 56% PCR (+), success rates, respectively. Individual, order and magnitude of a bite had no significant effect. The delay trial was repeated with WT from the wild, for which PCR (+) rate of the short amplicon was 63%, regardless of freshness. Four microsatellites were amplified from captive WT samples. We conclude that DNA from saliva traces can be recovered from WT, a potential new tool for noninvasive monitoring of possums and other wildlife.

Youth Risk Behavior Surveillance--United States, 1999. State and local YRBSS Coordinators.

Priority health-risk behaviors, which contribute to the leading causes of mortality and morbidity among youth and adults, often are established during youth, extend into adulthood, are interrelated, and are preventable. The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health-risk behaviors among youth and young adults--behaviors that contribute to unintentional and intentional injuries; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs) (including human immunodeficiency virus [HIV] infection); unhealthy dietary behaviors; and physical inactivity. The YRBSS includes a national school-based survey conducted by CDC as well as state, territorial, and local school-based surveys conducted by education and health agencies. This report summarizes results from the national survey, 33 state surveys, and 16 local surveys conducted among high school students during February through May 1999. In the United States, approximately three fourths of all deaths among persons aged 10-24 years result from only four causes: motor-vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1999 national Youth Risk Behavior Survey demonstrate that numerous high school students engage in behaviors that increase their likelihood of death from these four causes--16.4% had rarely or never worn a seat belt; during the 30 days preceding the survey, 33.1% had ridden with a driver who had been drinking alcohol; 17.3% had carried a weapon during the 30 days preceding the survey; 50.0% had drunk alcohol during the 30 days preceding the survey; 26.7% had used marijuana during the 30 days preceding the survey; and 7.8% had attempted suicide during the 12 months preceding the survey. Substantial morbidity and social problems among young persons also result from unintended pregnancies and STDs, including HIV infection. In 1999, nationwide, 49.9% of high school students had ever had sexual intercourse; 42.0% of sexually active students had not used a condom at last sexual intercourse; and 1.8% had ever injected an illegal drug. Two thirds of all deaths among persons aged > or = 25 years result from only two causes--cardiovascular disease and cancer. The majority of risk behaviors associated with these two causes of death are initiated during adolescence. In 1999, 34.8% of high school students had smoked cigarettes during the 30 days preceding the survey; 76.1% had not eaten > or = 5 servings/day of fruits and vegetables during the 7 days preceding the survey; 16.0% were at risk for becoming overweight; and 70.9% did not attend physical education class daily. These YRBSS data are already being used by health and education officials at national, state, and local levels to analyze and improve policies and programs to reduce priority health-risk behaviors among youth. The YRBSS data also are being used to measure progress toward achieving 16 national health objectives for 2010 and 3 of the 10 leading health indicators.

Youth risk behavior surveillance. National Alternative High School Youth Risk Behavior Survey, United States, 1998.

Alternative high schools serve approximately 280,000 students nationwide who are at high risk for failing or dropping out of regular high school or who have been expelled from regular high school because of illegal activity or behavioral problems. Such settings provide important opportunities for delivering health promotion education and services to these youth and young adults. However, before this survey, the prevalence of health-risk behaviors among students attending alternative high schools nationwide was unknown. The Youth Risk Behavior Surveillance System (YRBSS) monitors the following six categories of priority health-risk behaviors among youth and young adults: behaviors that contribute to unintentional and intentional injuries; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs) (including human immunodeficiency virus [HIV] infection); unhealthy dietary behaviors; and physical inactivity. The national Alternative High School Youth Risk Behavior Survey (ALT-YRBS) is one component of the YRBSS; it was conducted in 1998 to measure priority health-risk behaviors among students at alternative high schools. The 1998 ALT-YRBS used a three-stage cluster sample design to produce a nationally representative sample of students in grades 9-12 in the United States who attend alternative high schools. The school response rate was 81.0%, and the student response rate was 81.9%, resulting in an overall response rate of 66.3%. This report summarizes results from the 1998 ALT-YRBS. The reporting period is February-May 1998. In the United States, 73.6% of all deaths among youth and young adults aged 10-24 years results from only four causes--motor vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1998 ALT-YRBS demonstrate that many students at alternative high schools engage in behaviors that increase their likelihood of death from these four causes. During the 30 days preceding the survey, 51.9% had ridden with a driver who had been drinking alcohol, 25.1% had driven a vehicle after drinking alcohol, 32.9% had carried a weapon, 64.5% had drunk alcohol, and 53.0% had used marijuana. During the 12 months preceding the survey, 15.7% had attempted suicide, and 29.0% had rarely or never worn a seat belt. Substantial morbidity among school-aged youth and young adults also results from unintended pregnancies and STDs, including HIV infection. ALT-YRBS results indicate that in 1998, a total of 87.8% of students at alternative high schools had had sexual intercourse, 54.1% of sexually active students had not used a condom at last sexual intercourse, and 5.7% had ever injected an illegal drug. Among adults aged > or = 25 years, 66.5% of all deaths result from two causes--cardiovascular disease and cancer. Most risk behaviors associated with these causes of death are initiated during adolescence. In 1998, a total of 64.1% of students at alternative high schools had smoked cigarettes during the 30 days preceding the survey, 38.3% had smoked a cigar during the 30 days preceding the survey, 71.2% had not eaten > or = 5 servings of fruits and vegetables during the day preceding the survey, and 81.0% had not attended physical education (PE) class daily. Comparing ALT-YRBS results with 1997 national YRBS results demonstrates that the prevalence of most risk behaviors is higher among students attending alternative high schools compared with students at regular high schools. Some risk behaviors are more common among certain sex and racial/ethnic subgroups of students. ALT-YRBS data can be used nationwide by health and education officials to improve policies and programs designed to reduce risk behaviors associated with the leading causes of morbidity and mortality among students attending alternative high schools.

Youth risk behavior surveillance--United States, 1999.

PROBLEM/CONDITION: Priority health-risk behaviors, which contribute to the leading causes of mortality and morbidity among youth and adults, often are established during youth, extend into adulthood, are interrelated, and are preventable. REPORTING PERIOD: February-May 1999. DESCRIPTION OF THE SYSTEM: The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health-risk behaviors among youth and young adults --behaviors that contribute to unintentional and intentional injuries; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs) (including human immunodeficiency virus [HIV] infection); unhealthy dietary behaviors; and physical inactivity. The YRBSS includes a national school-based survey conducted by CDC as well as state, territorial, and local school-based surveys conducted by education and health agencies. This report summarizes results from the national survey, 33 state surveys, and 16 local surveys conducted among high school students during February-May 1999. RESULTS AND INTERPRETATION: In the United States, approximately three fourths of all deaths among persons aged 10-24 years result from only four causes: motor-vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1999 national Youth Risk Behavior Survey demonstrate that numerous high school students engage in behaviors that increase their likelihood of death from these four causes--16.4% had rarely or never worn a seat belt; during the 30 days preceding the survey, 33.1% had ridden with a driver who had been drinking alcohol; 17.3% had carried a weapon during the 30 days preceding the survey; 50.0% had drunk alcohol during the 30 days preceding the survey; 26.7% had used marijuana during the 30 days preceding the survey; and 7.8% had attempted suicide during the 12 months preceding the survey. Substantial morbidity and social problems among young persons also result from unintended pregnancies and STDs, including HIV infection. In 1999, nationwide, 49.9% of high school students had ever had sexual intercourse; 42.0% of sexually active students had not used a condom at last sexual intercourse; and 1.8% had ever injected an illegal drug. Two thirds of all deaths among persons aged > or = 25 years result from only two causes--cardiovascular disease and cancer. The majority of risk behaviors associated with these two causes of death are initiated during adolescence. In 1999, 34.8% of high school students had smoked cigarettes during the 30 days preceding the survey; 76.1% had not eaten > or = 5 servings/day of fruits and vegetables during the 7 days preceding the survey; 16.0% were at risk for becoming overweight; and 70.9% did not attend physical education class daily. ACTIONS TAKEN: These YRBSS data are already being used by health and education officials at national, state, and local levelsto analyze and improve policies and programs to reduce priority health-risk behaviors among youth. The YRBSS data also are being used to measure progress toward achieving 16 national health objectives for 2010 and 3 of the 10 leading health indicators.

Youth Risk Behavior Surveillance--National Alternative High School Youth Risk Behavior Survey, United States, 1998.

PROBLEM/CONDITION: Alternative high schools serve approximately 280,000 students nationwide who are at high risk for failing or dropping out of regular high school or who have been expelled from regular high school because of illegal activity or behavioral problems. Such settings provide important opportunities for delivering health promotion education and services to these youth and young adults. However, before this survey, the prevalence of health-risk behaviors among students attending alternative high schools nationwide was unknown. REPORTING PERIOD: February-May 1998. DESCRIPTION OF SYSTEM: The Youth Risk Behavior Surveillance System (YRBSS) monitors the following six categories of priority health-risk behaviors among youth and young adults: behaviors that contribute to unintentional and intentional injuries; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs) (including human immunodeficiency virus [HIV] infection); unhealthy dietary behaviors; and physical inactivity. The national Alternative High School Youth Risk Behavior Survey (ALT-YRBS) is one component of the YRBSS; it was conducted in 1998 to measure priority health-risk behaviors among students at alternative high schools. The 1998 ALT-YRBS used a three-stage cluster sample design to produce a nationally representative sample of students in grades 9-12 in the United States who attend alternative high schools. The school response rate was 81.0%, and the student response rate was 81.9%, resulting in an overall response rate of 66.3%. This report summarizes results from the 1998 ALT-YRBS. RESULTS AND INTERPRETATION: In the United States, 73.6% of all deaths among youth and young adults aged 10-24 years results from only four causes--motor vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1998 ALT-YRBS demonstrate that many students at alternative high schools engage in behaviors that increase their likelihood of death from these four causes. During the 30 days preceding the survey, 51.9% had ridden with a driver who had been drinking alcohol, 25.1% had driven a vehicle after drinking alcohol, 32.9% had carried a weapon, 64.5% had drunk alcohol, and 53.0% had used marijuana. During the 12 months preceding the survey, 15.7% had attempted suicide, and 29.0% had rarely or never worn a seat belt. Substantial morbidity among school-aged youth and young adults also results from unintended pregnancies and STDs, including HIV infection. ALT-YRBS results indicate that in 1998, a total of 87.8% of students at alternative high schools had had sexual intercourse, 54.1% of sexually active students had not used a condom at last sexual intercourse, and 5.7% had ever injected an illegal drug. Among adults aged > or =25 years, 66.5% of all deaths result from two causes--cardiovascular disease and cancer. Most risk behaviors associated with these causes of death are initiated during adolescence. In 1998, a total of 64.1% of students at alternative high schools had smoked cigarettes during the 30 days preceding the survey, 38.3% had smoked a cigar during the 30 days preceding the survey, 71.2% had not eaten > or =5 servings of fruits and vegetables during the day preceding the survey, and 81.0% had not attended physical education (PE) class daily. Comparing ALT-YRBS results with 1997 national YRBS results demonstrates that the prevalence of most risk behaviors is higher among students attending alternative high schools compared with students at regular high schools. Some risk behaviors are more common among certain sex and racial/ethnic subgroups of students. PUBLIC HEALTH ACTION: ALT-YRBS data can be used nationwide by health and education officials to improve policies and programs designed to reduce risk behaviors associated with the leading causes of morbidity and mortality among students attending alternative high schools.

Informed consent in school health research: why, how, and making it easy.

The obligation to obtain informed consent for student participation in health-related research creates a complex set of legal, ethical, and administrative responsibilities because the interests of research integrity are delicately balanced against protection of human subjects. Even the term itself sparks a range of responses depending on one's perspective and stake in the process. This paper traces the historical impetus behind obtaining informed consent, identifies key elements comprising informed consent, and reviews types of consent procedures used in schools. The authors suggest 20 ways to boost response rates while providing a realistic level of informed consent for school-based studies.

Youth Risk Behavior Surveillance--United States, 1997. State and Local YRBSS Coordinators.

Priority health-risk behaviors, which contribute to the leading causes of mortality and morbidity among youth and adults, often are established during youth, extend into adulthood, and are interrelated. The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health-risk behaviors among youth and young adults--behaviors that contribute to unintentional and intentional injuries; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs) (including human immunodeficiency virus [HIV] infection); unhealthy dietary behaviors; and physical inactivity. The YRBSS includes a national school-based survey conducted by the Centers for Disease Control and Prevention as well as state, territorial, and local school-based surveys conducted by education and health agencies. This report summarizes results from the national survey, 33 state surveys, 3 territorial surveys, and 17 local surveys conducted among high school students from February through May 1997. In the United States, 73% of all deaths among youth and young adults 10-24 years of age result from only four causes: motor vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the national 1997 YRBSS demonstrate that many high school students engage in behaviors that increase their likelihood of death from these four causes--19.3% had rarely or never worn a seat belt; during the 30 days preceding the survey, 36.6% had ridden with a driver who had been drinking alcohol; 18.3% had carried a weapon during the 30 days preceding the survey; 50.8% had drunk alcohol during the 30 days preceding the survey; 26.2% had used marijuana during the 30 days preceding the survey; and 7.7% had attempted suicide during the 12 months preceding the survey. Substantial morbidity among school-age youth, young adults, and their children also result from unintended pregnancies and STDs, including HIV infection. YRBSS results indicate that in 1997, 48.4% of high school students had ever had sexual intercourse; 43.2% of sexually active students had not used a condom at last sexual intercourse; and 2.1% had ever injected an illegal drug. Of all deaths and substantial morbidity among adults greater than or equal to 25 years of age, 67% result from two causes--cardiovascular disease and cancer. Most of the risk behaviors associated with these causes of death are initiated during adolescence. In 1997, 36.4% of high school students had smoked cigarettes during the 30 days preceding the survey; 70.7% had not eaten five or more servings of fruits and vegetables during the day preceding the survey; and 72.6% had not attended physical education class daily. These YRBSS data are already being used by health and education officials to improve national, state, and local policies and programs to reduce risks associated with the leading causes of morbidity and mortality. YRBSS data also are being used to measure progress toward achieving 21 national health objectives and one of the eight National Education Goals.

Mutation in region III of the DNA polymerase gene conferring foscarnet resistance in cytomegalovirus isolates from 3 subjects receiving prolonged antiviral therapy.

Three human immunodeficiency virus-infected subjects with progressive cytomegalovirus (CMV) retinitis despite prolonged antiviral therapy had buffy coat CMV isolates that were resistant to both ganciclovir and foscarnet. Genetic analysis of the resistant isolates showed that each contained a well-known ganciclovir resistance mutation in the viral UL97 phosphotransferase sequence, as well as a mutation (Ala to Val at codon 809, V809) in conserved region III of the DNA polymerase (Pol) sequence. A segment of the Pol sequence from one of the clinical isolates was transferred to CMV laboratory strain AD169 by homologous recombination. The recombinant virus containing V809 showed 6.3-fold increased foscarnet resistance and 2.6-fold increased ganciclovir resistance. Occurrence of the V809 mutation in 3 unrelated cases suggests that it is a clinically significant viral genetic marker for foscarnet resistance and decreased susceptibility to ganciclovir.

Youth risk behavior surveillance--United States, 1997.

PROBLEM/CONDITION: Priority health-risk behaviors, which contribute to the leading causes of mortality and morbidity among youth and adults, often are established during youth, extend into adulthood, and are interrelated. REPORTING PERIOD: February-May 1997. DESCRIPTION OF THE SYSTEM: The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health-risk behaviors among youth and young adults--behaviors that contribute to unintentional and intentional injuries; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs) (including human immunodeficiency virus [HIV] infection); unhealthy dietary behaviors; and physical inactivity. The YRBSS includes a national school-based survey conducted by CDC as well as state, territorial, and local school-based surveys conducted by education and health agencies. This report summarizes results from the national survey, 33 state surveys, 3 territorial surveys, and 17 local surveys conducted among high school students from February through May 1997. RESULTS AND INTERPRETATION: In the United States, 73% of all deaths among youth and young adults 10-24 years of age result from only four causes: motor vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the national 1997 YRBSS demonstrate that many high school students engage in behaviors that increase their likelihood of death from these four causes--19.3% had rarely or never worn a seat belt; during the 30 days preceding the survey, 36.6% had ridden with a driver who had been drinking alcohol; 18.3% had carried a weapon during the 30 days preceding the survey; 50.8% had drunk alcohol during the 30 days preceding the survey; 26.2% had used marijuana during the 30 days preceding the survey; and 7.7% had attempted suicide during the 12 months preceding the survey. Substantial morbidity among school-age youth, young adults, and their children also result from unintended pregnancies and STDs, including HIV infection. YRBSS results indicate that in 1997, 48.4% of high school students had ever had sexual intercourse; 43.2% of sexually active students had not used a condom at last sexual intercourse; and 2.1% had ever injected an illegal drug. Of all deaths and substantial morbidity among adults > or = 25 years of age, 67% result from two causes--cardiovascular disease and cancer. Most of the risk behaviors associated with these causes of death are initiated during adolescence. In 1997, 36.4% of high school students had smoked cigarettes during the 30 days preceding the survey; 70.7% had not eaten five or more servings of fruits and vegetables during the day preceding the survey; and 72.6% had not attended physical education class daily. ACTIONS TAKEN: These YRBSS data are already being used by health and education officials to improve national, state, and local policies and programs to reduce risks associated with the leading causes of morbidity and mortality. YRBSS data also are being used to measure progress toward achieving 21 national health objectives and 1 of the 8 National Education Goals.

Results from the 1995 National College Health Risk Behavior Survey.

Results from the 1995 National College Health Risk Behavior Survey, which monitored health risk behaviors among US college and university undergraduates, suggest that many students' behaviors increase their likelihood of adverse health outcomes. During the 30 days preceding the survey, 34% of the participants had consumed five or more alcoholic drinks on at least one occasion, and 27% had drunk alcohol and driven a car. Thirty-one percent had smoked cigarettes regularly during their lifetimes, 49% had ever used marijuana, 30% had used a condom during their last sexual intercourse, 21% were overweight, and 38% had participated in vigorous physical activity on 3 or more of the 7 days preceding the survey. These data were analyzed by gender, age group, race and ethnicity, and institution type. They can be used by those responsible for the health and education of college students to reduce risks associated with the leading causes of mortality and morbidity.

Youth risk behavior surveillance--United States, 1995.

Priority health-risk behaviors that contribute to the leading causes of mortality, morbidity, and social problems among youth and adults often are established during youth, extend into adulthood, and are interrelated. The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health-risk behaviors among youth and young adults: behaviors that contribute to unintentional and intentional injuries, tobacco use, alcohol and other drug use, sexual behaviors, unhealthy dietary behaviors, and physical inactivity. The YRBSS includes both a national school-based survey conducted by CDC and state and local school-based surveys conducted by state and local education agencies. This report summarizes results from the national survey, 35 state surveys, and 16 local surveys conducted among high school students from February through May 1995. In the United States, 72% of all deaths among school-age youth and young adults result from four causes: motor vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1995 YRBSS suggest that many high school students practice behaviors that may increase their likelihood of death from these four causes: 21.7% had rarely or never used a safety belt, 38.8% had ridden with a driver who had been drinking alcohol during the 30 days preceding the survey, 20.0% had carried a weapon during the 30 days preceding the survey, 51.6% had drunk alcohol during the 30 days preceding the survey, 25.3% had used marijuana during the 30 days preceding the survey, and 8.7% had attempted suicide during the 12 months preceding the survey. Substantial morbidity and social problems among school-age youth and young adults also result from unintended pregnancies and sexually transmitted diseases, including HIV infection. YRBSS results indicate that in 1995, 53.1% of high school students had experienced sexual intercourse, 45.6% of sexually active students had not used a condom at last sexual intercourse, and 2.0% had ever injected an illegal drug. Among adults, 65% of all deaths result from three causes: heart disease, cancer, and stroke. Most of the risk behaviors associated with these causes of death are initiated during adolescence. In 1995, 34.8% of high school students had smoked cigarettes during the 30 days preceding the survey, 39.5% had eaten more than two servings of foods typically high in fat content during the day preceding the survey, and only 25.4% had attended physical education class daily. YRBSS data are being used nationwide by health and education officials to improve national, state, and local policies and programs designed to reduce risks associated with the leading causes of mortality and morbidity. YRBSS data also are being used to measure progress toward achieving 21 national health objectives and one of eight National Education Goals.

Youth Risk Behavior Surveillance--United States, 1995.

PROBLEM/CONDITION: Priority health-risk behaviors that contribute to the leading causes of mortality, morbidity, and social problems among youth and adults often are established during youth, extend into adulthood, and are interrelated. REPORTING PERIOD: February through May 1995. DESCRIPTION OF THE SYSTEM: The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health-risk behaviors among youth and young adults: behaviors that contribute to unintentional and intentional injuries, tobacco use, alcohol and other drug use, sexual behaviors, unhealthy dietary behaviors, and physical inactivity. The YRBSS includes both a national school-based survey conducted by CDC and state and local school-based surveys conducted by state and local education agencies. This report summarizes results from the national survey, 35 state surveys, and 16 local surveys conducted among high school students from February through May 1995. RESULTS AND INTERPRETATION: In the United States, 72% of all deaths among school-age youth and young adults result from four causes: motor vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1995 YRBSS suggest that many high school students practice behaviors that may increase their likelihood of death from these four causes: 21.7% had rarely or never used a safety belt, 38.8% had ridden with a driver who had been drinking alcohol during the 30 days preceding the survey, 20.0% had carried a weapon during the 30 days preceding the survey, 51.6% had drunk alcohol during the 30 days preceding the survey, 25.3% had used marijuana during the 30 days preceding the survey, and 8.7% had attempted suicide during the 12 months preceding the survey. Substantial morbidity and social problems among school-age youth and young adults also result from unintended pregnancies and sexually transmitted diseases, including human immunodeficiency virus infection. YRBSS results indicate that in 1995, 53.1% of high school students had had sexual intercourse, 45.6% of sexually active students had not used a condom at last sexual intercourse, and 2.0% had ever injected an illegal drug. Among adults, 65% of all deaths result from three causes: heart disease, cancer and stroke. Most of the risk behaviors associated with these causes of death are initiated during adolescence. In 1995, 34.8% of high school students had smoked cigarettes during the 30 days preceding the survey, 39.5% had eaten more than two servings of foods typically high in fat content during the day preceding the survey, and only 25.4% had attended physical education class daily. ACTIONS TAKEN: YRBSS data are being used nationwide by health and education officials to improve national, state, and local policies and programs designed to reduce risks associated with the leading causes of mortality and morbidity. YRBSS data also are being used to measure progress toward achieving 21 national health objectives and one of eight National Education Goals.

Youth risk behavior surveillance--United States, 1993.

Priority health risk behaviors that contribute to the leading causes of mortality, morbidity, and social problems among youth and adults often are established during youth, extend into adulthood, and are interrelated. The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health risk behaviors among youth and youth adults: behaviors that contribute to unintentional and intentional injuries, tobacco use, alcohol and other drug use, sexual behaviors, dietary behaviors, and physical activity. The YRBSS includes a national, school-based survey conducted by CDC and state and local school-based surveys conducted by state and local education agencies. This report summarizes results from the national survey, 24 state surveys, and nine local surveys conducted among high school students during February through May 1993. In the United States, 72% of all deaths among school-age youth and young adults are from four causes: motor vehicle crashes, other intentional injuries, homicide, and suicide. Results from the 1993 YRBSS suggest many high school students practice behaviors that may increase their likelihood of death from these four causes: 19.1% rarely or never use a safety belt, 35.3% had ridden during the 30 days preceding the survey with a driver who had been drinking alcohol, 22.1% had carried a weapon during the 30 days preceding the survey, 80.9% ever drank alcohol, 32.8% ever used marijuana, and 8.6% had attempted suicide during the 12 months preceding the survey. Substantial morbidity and social problems among adolescents also result from unintended pregnancies and sexually transmitted diseases including HIV infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Youth risk behavior surveillance--United States, 1993.

PROBLEM/CONDITION: Priority health risk behaviors that contribute to the leading causes of mortality, morbidity, and social problems among youth and adults often are established during youth, extend into adulthood, and are interrelated. REPORTING PERIOD: February through May 1993. DESCRIPTION OF SYSTEM: The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health risk behaviors among youth and young adults: behaviors that contribute to unintentional and intentional injuries, tobacco use, alcohol and other drug use, sexual behaviors, dietary behaviors, and physical activity. The YRBSS includes a national, school-based survey conducted by CDC and state and local school-based surveys conducted by state and local education agencies. This report summarizes results from the national survey, 24 state surveys, and nine local surveys conducted among high school students during February through May 1993. RESULTS AND INTERPRETATION: In the United States, 72% of all deaths among school-age youth and young adults are from four causes: motor vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1993 YRBSS suggest that many high school students practice behaviors that may increase their likelihood of death from these four causes: 19.1% rarely or never used a safety belt, 35.3% had ridden with a driver who had been drinking alcohol during the 30 days preceding the survey, 22.1% had carried a weapon during the 30 days preceding the survey, 80.9% ever drank alcohol, 32.8% ever used marijuana, and 8.6% had attempted suicide during the 12 months preceding the survey. Substantial morbidity and social problems among adolescents also result from unintended pregnancies and sexually transmitted diseases, including human immunodeficiency virus (HIV) infection. YRBSS results indicate that in 1993, 53.0% of high school students had had sexual intercourse, 52.8% of sexually active students had used a condom during last sexual intercourse, and 1.4% ever injected an illegal drug. Among adults, 67% of all deaths are from three causes: heart disease, cancer, and stroke. In 1993, many high school students practiced behaviors that may increase the risk for these health problems: 30.5% of high school students had smoked cigarettes during the 30 days preceding the survey, only 15.4% had eaten five or more servings of fruits and vegetables during the day preceding the survey, and only 34.3% had attended physical education class daily. ACTIONS TAKEN: YRBSS data are being used nationwide by health and education officials to improve school health policies and programs designed to reduce risks associated with the leading causes of mortality and morbidity. At the national level, YRBSS data are being used to measure progress toward achieving 26 national health objectives and one of eight National Education Goals.

Dietary electrolyte balance effects on performance and metabolic characteristics in growing steers.

The effects of dietary electrolyte balance (DEB; mEq of Na + K - Cl/100 g of DM) on performance and acid-base status of growing cattle consuming a corn silage-based diet were established using 120 Angus (n = 60) and Angus crossbred (n = 60) steers (247 +/- 2.4 kg). Treatments consisting of 0, 15, 30, or 45 mEq of DEB/100 g of DM were obtained by varying NH4Cl and NaHCO3. Average daily gain showed a linear increase (P < .05) with increased DEB for the first 28 d and a quadratic response (P < .05) for the remainder of the 84-d study. Average daily feed intake was not affected by DEB the first 28 d. However, feed intake over the entire feeding period showed a linear increase with increasing DEB (P < .01). On d 28, plasma Na, K, and Mg were not affected by DEB, whereas Ca followed a quadratic pattern (P < .10). On d 84, plasma Na and Mg decreased linearly with increasing DEB. Plasma Cl concentrations decreased linearly (P < .01) with increased DEB on d 28 and 84. On d 28 arterial blood pH and HCO3 increased linearly (P < .05) with increased DEB, whereas ionized Ca, pCO2, and pO2 were unchanged. On d 84, arterial blood pH (P < .10), HCO3 (P < .05), and ionized Ca (P < .10) increased quadratically, whereas pO2 and pCO2 were not affected by treatment. Ruminal pH increased linearly (P < .05) with increased DEB on d 28 but showed no differences on d 84. These data indicate that DEB affects performance and systemic values in growing feedlot cattle. A DEB in the range of 15 to 30 mEq seemed to provide normal homeostasis of growing steers fed a corn silage-based diet.