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Biomedical subjects

D Hemenway

Publications and source records attributed to D Hemenway.

At least 19 recordsLinked to original sources

Age-within-school-class and adolescent gun-carrying.

BACKGROUND: Intentional injuries (suicide and homicide) are a leading causes of morbidity and mortality in the United States. Firearms cause approximately 70% of these fatal intentional injuries. Risk factors associated with gun-carrying in adolescent populations include male gender, smoking, alcohol use, drug use, and number of sexual partners. Current knowledge of these and other risk factors has provided limited benefit because many are no more obvious to the clinician a priori than is the tendency to carry guns. Increasing relative age of a student within school class is an easily measured parameter that has been associated with behavioral problems, absenteeism, negative self-image, and high dropout rates. OBJECTIVE: To characterize the association between relative student age-within-class and tendency to carry firearms. DESIGN: The Massachusetts Youth Risk Behavior Survey, which collects data on demographic characteristics, risk behaviors, and health outcomes. PARTICIPANTS: A randomly selected group of 3153 Massachusetts students in grades 9 through 11. PRIMARY OUTCOME MEASURE: The odds of firearms-carrying comparing older to average-age and younger students. RESULTS: Using multivariate logistic regression, seven risk factors predicted gun-carrying with statistically significant results: older age-within-class (OR: 2.12; 95% CI: 1.09-4.12), male gender (OR: 4.95; 95% CI: 3.01-8.15), black race (OR: 2.49; 95% CI: 1.20-5.14), gang membership (OR: 7.22; 95% CI: 4.51-11.56), missing school out of concern for safety (OR: 2.50; 95% CI: 1.30-4.80), seeking medical treatment after a fight (OR: 4.47; 95% CI: 2.56-7. 78), and fighting without seeking medical treatment (OR: 5.73; 95% CI: 3.09-10.60). CONCLUSION: Older 9th-, 10th-, and 11th-grade students are more likely than their classmates to carry firearms. This information may prove helpful in identifying high-risk students and targeting prevention strategies.

Adolescent

Using a hypothetical case to measure differences in treatment aggressiveness among physicians in Canada, Germany and the United States.

Variations in physician practice style, within and between countries, account for much of the differences in the utilization of scarce health care resources. Practice style differences are particularly important at the end of life, when a substantial amount of resources are consumed. We use a hypothetical case of a severely ill elderly patient to identify factors associated with aggressive treatment and to test whether physicians in the US practice differently from their counterparts in other countries. Data come from a random sample of practicing physicians in three industrialized countries, the United States, Canada and Germany (N = 1369). Although the case stated that the chance of survival of the patient was low, 73% of all physicians selected the aggressive treatment. Physicians from the United States were the most aggressive (86%), followed by Germany (68%) and Canada (61%). Practicing in the United States was the strongest predictor of aggressiveness in the multiple linear logistic regression; German and Canadian physicians were one fourth as likely to use aggressive treatment. Specialty training, older age and being a resident all increased the likelihood of selecting the more aggressive treatment. The fear of being sued for malpractice and income did not have an effect on treatment decisions.

Adult

Ambient particulate matter causes activation of the c-jun kinase/stress-activated protein kinase cascade and DNA synthesis in lung epithelial cells.

Numerous epidemiological studies have demonstrated a positive association between ambient air pollution and adverse health effects including respiratory morbidity, asthma, and lung cancer. It has been suggested in some experimental studies that airborne particulate matter (PM) can produce inflammatory effects, but nothing is known about the possible proliferative and carcinogenic effects of these particles on cells of the lung. We show here that exposure of pulmonary epithelial cells, a cell type affected in acute lung injury, asthma, and lung carcinomas, to nontoxic concentrations of PM in vitro results in increases in c-jun kinase activity, levels of phosphorylated cJun immunoreactive protein, and transcriptional activation of activator protein-1-dependent gene expression. These changes are accompanied by elevations in numbers of cells incorporating 5'-bromodeoxyuridine, a marker of unscheduled DNA synthesis and/or cell proliferation. Data here are the first to demonstrate that interaction of ambient PM with target cells of the lung initiates a cell signaling cascade related causally to aberrant cell proliferation and carcinogenesis.

Air Pollution

Mechanisms of asbestos-induced nitric oxide production by rat alveolar macrophages in inhalation and in vitro models.

To evaluate the contribution of reactive nitrogen species to inflammation by asbestos, Fischer 344 rats were exposed to crocidolite or chrysotile asbestos by inhalation to determine whether increases occurred in nitric oxide (NO.) metabolites from alveolar macrophages (AMs). AMs from animals inhaling asbestos showed significant elevations (p < .05) in nitrite/nitrate levels which were ameliorated by NG-monomethyl-L-arginine (NMMA), an inhibitor of inducible nitric oxide synthase (iNOS) activity. Temporal patterns of NO. generation from AMs correlated with neutrophil influx in bronchoalveolar lavage samples after asbestos inhalation or bleomycin instillation, another model of pulmonary fibrosis. To determine the molecular mechanisms and specificity of iNOS promoter activation by asbestos, RAW 264.7 cells, a murine macrophage-like line, and AMs isolated from control rats were exposed to crocidolite asbestos in vitro. These cells showed increases in steady-state levels of iNOS mRNA in response to asbestos and more dramatic increases in both iNOS mRNA and immunoreactive protein after addition of lipopolysaccharide (LPS). After transfection of an iNOS promoter/luciferase reporter construct, RAW 264.7 cells exposed to LPS, crocidolite asbestos and its nonfibrous analog, riebeckite, revealed increases in luciferase activity whereas cristobalite silica had no effects. Studies suggest that NO. generation may be important in cell injury and inflammation by asbestos.

Administration, Inhalation

Did changes in minimum age drinking laws affect adolescent drowning (1970-90)?

OBJECTIVE: To test the hypothesis that changes in the minimum legal drinking age (MLDA) laws would affect drowning among adolescents, the effects of changes in state MLDA laws on drowning were examined for the targeted (18-20 years) and two adjacent (15-17 years and 21-23 years) age groups, over a period of 21 years (1970-90). METHODS: Poisson maximum likelihood regression was used to estimate the effects of both lowering and increasing the MLDA. The dependent variable in these analyses was the number of drownings per state per year for the age groups observed. At first only state and year effects were controlled for and then any other variable potentially associated with the incidence of drowning was included. The other control variables included proportion of population living near border states with lower MLDA laws, urbanicity, unemployment, divorce, education, poverty, beer tax, and proxy measures for MLDA law enforcement. RESULTS: No significant association between drowning and MLDA was found for any of the age groups studied. CONCLUSION: It is concluded that MLDA laws are not an important public policy strategy for affecting drowning rates among adolescents and young adults.

Adolescent

Characteristics of automatic or semiautomatic firearm ownership in the United States.

OBJECTIVES: This study examined ownership patterns of automatic/ semiautomatic firearms in the United States. METHODS: Data were derived from a national random-digit-dialing telephone survey of 800 gun owners. RESULTS: Sixty percent of gun owners reported owning an automatic or semiautomatic firearm. In comparison with other gun owners, owners of automatics or semiautomatics were more likely to be male, live in the South, own a gun for protection, and have a gun for work. They were also more likely to report binge drinking. CONCLUSIONS: Owners of automatic or semiautomatic firearms differ from other gun owners in several respects, including frequency of binge drinking.

Adult

Comparative proliferative and histopathologic changes in rat lungs after inhalation of chrysotile or crocidolite asbestos.

Patterns of cell proliferation in lung and pleura and development of histopathologic lesions were studied in lungs from Fischer 344 rats after inhalation exposure to chrysotile or crocidolite asbestos at average airborne concentrations of approximately 8 mg/m3 air for 5 and 20 days and after 20 days of exposure followed by an additional 20 days in room air (20 + 20 days). To assess cell proliferation rats were injected with 5-bromo-2'-deoxyuridine (BrdU) at various time points after initiation of exposure to asbestos. Image analysis was used to quantitate the effects of chrysotile and crocidolite on BrdU labeling indices in the following lung compartments: (1) interstitium, (2) alveolar duct region, (3) bronchial epithelium, and (4) visceral mesothelium. With the exception of mesothelium, which exhibited significant increases in BrdU incorporation in rats exposed to crocidolite at 20 + 20 days, asbestos-induced elevations in BrdU uptake in other compartments were transient with labeling comparable to sham controls at later time points. Histopathology of rat lungs revealed fibrotic lesions of a greater extent and severity at 20 days in rats exposed to crocidolite, but fibrosis occurred in both asbestos-exposed groups after an additional 20 days in clean air (20 + 20). Quantification of fiber burden in rat lung after inhalation of comparable airborne concentrations of either fiber type demonstrated that inhalation of crocidolite asbestos led to a higher fiber retention when compared to chrysotile asbestos. Our results indicate that chrysotile and crocidolite asbestos induce different patterns of cell proliferation in lung and pleural cells. The protracted increases in BrdU labeling of mesothelial cells by crocidolite may reflect increased retention of fibers and/or inherent differences between types of asbestos.

Administration, Inhalation

Seat belt use, insurance status, and hospital bad debt.

OBJECTIVES: Previous studies have shown that not wearing a seat belt is associated with both increased injury severity and higher hospital charges. In this article, we examine whether unrestrained motorists are also more likely (a) to be medically uninsured, and (b) to leave their hospital bills unpaid. METHODS: We reviewed the hospital clinical and billing records for all occupants in motor vehicle collisions admitted to the Massachusetts General Hospital Emergency Department during a 2-month period (n = 265). Using data on seat belt use, insurance status, bad debt, admission to the hospital, driver or passenger status, age and sex, we performed simple correlation and multiple regression analyses to determine the association between (a) seat belt use and insurance status and (b) seat belt use and hospital bad debt. RESULTS: Unrestrained patients were more likely both to be uninsured and, holding insurance status and other factors constant, to generate bad debt for the hospital. CONCLUSIONS: Our findings are similar to previous studies that show that the public pays a significant share of the medical care charges associated with risk-taking behavior. Propitious selection, an economic theory, may explain such findings. It asserts that risk-taking individuals are least likely to buy insurance voluntarily and will also be the ones most likely to deliberately place themselves in dangerous situations. Our findings show that people who do not use seat belts are more likely to have outstanding hospital bills; the public effectively pays for these bills in higher taxes or insurance premiums.

Accidents, Traffic

Guns in young hands: a survey of urban teenagers' attitudes and behaviors related to handgun violence.

OBJECTIVE: To determine the nature and causes of gun violence among urban young people. METHODS: We conducted a confidential survey of 1,219 7th and 10th graders in Boston and Milwaukee, regarding their attitudes and behaviors toward violence and handguns. RESULTS: Twenty-nine percent have had a member of their immediate family shot, 42% could get a gun if they wanted, 28% have handled a gun without adult knowledge or supervision, 17% have carried a concealed gun, and 3% reported bringing a gun to school in the past 30 days. Nine percent admitted smoking cigarettes in the past week, 11% admitted smoking marijuana. Twenty-five percent were attacked or threatened within the past year. Reasons for gun carrying were mostly related to perceived safety/threats/revenge (73%), followed by casual handling (17%), hunting (4%), being cool (3%), target practice (2%), and gangs (1%). The following factors were significantly correlated with gun handling by chi 2 analysis, at p < 0.001 (percentage of respondents admitting unsupervised gun handling shown in parentheses): male (39%) versus female (19%); 10th graders (35%) versus 7th graders (24%) seat-belt nonusers (35%) versus users (20%); students who state they have poor grades (39%) versus good grades (26%); cigarette smokers (61%) versus nonsmokers (25%); have a gun in the home (46%) versus no gun in the home (23%). Also strongly correlated in multivariate analysis were violence exposure, having been arrested, and beliefs that "gun carrying is a good idea," or that "only cowards back down from a fight." CONCLUSIONS: Handgun availability and use are high among urban youth; gun carrying is mostly related to safety concerns and easy access, rather than to hunting or sport. This may be a cause of high handgun injury rates in this group. Gun injury prevention programs must address youth safety concerns along with handgun availability.

Adolescent

Firearm training and storage.

OBJECTIVE: To determine the extent of firearm training among gun owners, how gun owners currently store their weapons, and the relationship between gun training and gun storage. DESIGN AND SETTING: A national random telephone survey of gun owners conducted from May through June 1994. PARTICIPANTS: A total of 800 adult gun owners residing in the United States. MAIN OUTCOME MEASURES: Number of gun owners who received firearm training and number who store a firearm loaded and unlocked. Logistic regression analyses were conducted to examine factors associated with firearm training and gun storage practices. RESULTS: A total of 451 (56%) of gun owners have received firearm training. A total of 170 (21%) of gun owners keep a firearm both loaded and unlocked in the home. Factors associated with an increased likelihood of storing guns loaded and unlocked included owning a gun for protection (odds ratio [OR], 2.40; 95% confidence interval [CI], 1.62 to 3.54), owning a handgun (OR, 3.31; 95% CI, 1.85 to 5.95), and having received firearm training (OR, 1.71; 95% CI, 1.10 to 2.67). Length of firearm training and how recently training was received have little effect on storage practices. CONCLUSION: It has been suggested that many homicide, suicide, and accidental firearm injuries might be prevented if ready access to lethal weapons was reduced, in part through appropriate storage of guns. Although increased training has been advocated as the prime method to improve gun storage practices, our results cast doubt on whether firearm training, at least as currently provided, will substantially reduce the inappropriate storage of firearms.

Adult

The hit-and-run in fatal pedestrian accidents: victims, circumstances and drivers.

Hit-and-run pedestrian fatalities are classified as to victim characteristics, accident circumstances and driver characteristics. Over 18,000 pedestrian fatalities are reported in the Fatal Accident Recording System for 1989-1991. Twenty percent of the drivers involved left the accident scene. Children and senior citizens are the least likely to be left. Drivers more commonly run in urban areas, outside the South, on weekends and at night. Comparing motorists who left the scene but were later identified with the drivers who remained, drivers aged 66 and older are half as likely as younger drivers to leave the accident scene and male drivers are 60% more likely than female drivers to run. Drivers with previous driving while intoxicated arrests are twice as likely to run as those with no such arrests. Forty-nine percent of hit-and-run motorists involved in pedestrian fatalities are ultimately identified by the police. Other factors constant, drivers are more likely to be identified if the victim was female or a child. Drivers are identified 2.5 times as often when the incident occurred in daylight. Drivers appear to run more often when they are at fault and will be severely punished (e.g. when they are intoxicated) and when it is likely that they can escape detection (e.g. at night).

Accidents, Traffic

Body height and hip fracture: a cohort study of 90,000 women.

BACKGROUND: Hip fractures are a major public health problem. Recent studies have noted a connection between body height and hip fracture. METHODS: We investigated the relationship between body height and hip fracture using a prospective cohort of over 92,000 American, predominantly white, female nurses who were followed for 10 years, from June 1980 to June 1990. The women, participants in the Nurses Health Study, were aged 35-59 in 1980. RESULTS: Women 5'8" or taller were more than twice as likely as women under 5'2" to sustain a hip fracture, after accounting for age, body mass index, cigarette smoking and alcohol consumption (multivariate relative risk 2.40, 95% confidence interval: 1.43-4.02; P for trend < 0.0001). CONCLUSION: Height appears to be an important independent risk factor for hip fracture among American women. Height should be included as a confounder in studies of hip fracture, and taller, elderly women should be advised to consider preventive measures.

Adult

Patterns of inflammation, cell proliferation, and related gene expression in lung after inhalation of chrysotile asbestos.

Biochemical and molecular markers of inflammation, cell proliferation, and pulmonary fibrosis were studied in lungs and bronchoalveolar lavage preparations from Fischer 344 rats at time periods from 3 to 20 days after inhalation of two airborne concentrations (0.18 and 8.2 mg/m3 air) of chrysotile asbestos. Additional groups of animals were examined for lung histopathology and cell proliferation with an antibody to 5-bromo-2'-deoxyuridine after exposure to asbestos for 5 and 20 days and after 20 days of exposure followed by an additional 20 days in room air. Exposure to chrysotile at the higher concentration caused protracted increases in steady-state mRNA levels of manganese-containing superoxide dismutase and elevation in glyceraldehyde-3-phosphate dehydrogenase mRNA at 3 days, but levels of mRNAs encoding copper-zinc-containing superoxide dismutase, ornithine decarboxylase, and the proto-oncogene, c-jun were not statistically elevated from levels occurring in lung homogenates from sham control rats. Differential cell counts in bronchoalveolar lavage revealed an early infiltration of neutrophils that correlated with focal areas of increased cellularity and fibrosis in rat lungs at the higher concentrations of asbestos. However, elevations in lung hydroxyproline were not observed. Significant increases in epithelial cells of the bronchi, the interstitial compartment of the lung, and mesothelial cells incorporating 5-bromo-2'-deoxyuridine, an indication of DNA synthesis, were noted in the higher chrysotile group at 5 days, but labeling in all cell compartments was comparable with that occurring in sham controls at later time points. Indicators of inflammation, increased cell proliferation, and pulmonary fibrosis were not observed in the lungs of rats exposed to the lower concentration of chrysotile. Thus, results indicate that cellular and molecular markers of inflammation and proliferation in lung are dose-related and indicative of the histopathological development of asbestosis.

Administration, Inhalation

Risk factors for wrist fracture: effect of age, cigarettes, alcohol, body height, relative weight, and handedness on the risk for distal forearm fractures in men.

Fractures of the distal forearm (wrist) are among the most common of all fractures. While evidence exists concerning risk factors for wrist fracture among women, little is known about risk factors among men. This study examines the relation of lifestyle characteristics (cigarette smoking, alcohol consumption, relative weight) as well as body height and handedness to the risk for fracture in a male population that has been followed up for 6 years. The 51,529 men, who were between the ages of 40 and 75 years in 1986, were participants in the Health Professionals Follow-up Study, a national prospective cohort study. In 271,552 person-years of follow-up, 271 respondents reported a wrist fracture. The risk for wrist fracture in this population did not vary with age. Cigarette smoking, alcohol consumption, body height, and relative weight also were not related to risk for wrist fracture. Handedness, which was divided into four mutually exclusive categories (right-handed, left-handed, forced to change, and ambidextrous), was significantly associated with wrist fracture. Left-handers had a multivariate relative risk for wrist fracture 1.56 times that of right-handers (95% confidence interval 1.02-2.37), and men who reported they had been forced to change from left-handed to right-handed had a multivariate relative risk 2.47 times greater than right-handers (95 percent confidence interval 1.21-5.04).

Adult