Cigarette use in adolescents: the Cardiovascular Health in Children and Youth Study.

Tobacco is the leading cause of preventable death in the United States, and its use is increasing in adolescents. To determine the interventions needed to prevent the initiation of smoking, it is important to know the factors related to tobacco use by adolescents. In this study the following factors related to cigarette use were examined: age, gender, ethnicity, self-esteem, physical activity, parental smoking, and socioeconomic status. Participants were 1,207 youth completing a written survey for the Cardiovascular Health in Children and Youth Study (CHIC II). Participants ranged in age from 10 to 15 years, with a mean age of 12.2 years; 64.2% were White, 24.0% Black, 5.8% Hispanic, and 6.0% other races. White and Hispanic youth and youth of other races had significantly higher rates of smoking than did Black youth. Significant risk factors for smoking were: higher grade in school, White race, and for girls only, lower self-esteem. In White youth those in the lowest socioeconomic status were most likely to be current and experimental smokers. Smoking was as common in girls as in boys at these ages. Multivariate analysis showed that neither physical activity nor parental smoking were significant predictors of smoking behaviors. These results suggest that smoking prevention programs for adolescents should specifically target White and Hispanic youth and those from families with low socioeconomic status. In addition, these interventions should include ways to increase self-esteem in girls.

Smokeless tobacco use in adolescents: the Cardiovascular Health in Children (CHIC II) Study.

Smokeless tobacco has seen a resurgence of popularity among adolescents despite its association with oral cancer and altered cardiovascular function. This study examined age, gender, ethnicity, self-esteem, physical activity, parental smoking, and socioeconomic status as predictors of smokeless tobacco use among middle school children. Subjects included 1,211 youth (White (64%), Black (24%), Hispanic (6%), and Other (6%); age 12.2) participating in the Cardiovascular Health in Children and Youth (CHIC II) study. All data were collected by questionnaire. Factors related to ever using smokeless tobacco included older age (p < .001), being male (p < .001), lower self-esteem (p < .001), and having parents who currently (p = .02) or formerly (p = .05) smoked. Hispanics reported a higher current usage rate than other ethnic groups (p < .001). White youth in the lowest socioeconomic status were most likely to be experimental users (p = .007), while those in the high socioeconomic status were more likely to be current users (p = .006). Physical activity was not associated with smokeless tobacco use.

A community survey of alcohol consumption.

A survey by 150 trained medical students was carried out in 1986 on a random sample of adults from the electoral register of Cardiff. The survey explored attitudes, knowledge and behaviour over a wide range of health related topics. 4266 self-completed questionnaires were returned for analysis and this paper reports the answers to the question 'how much did you drink last week'. The total units of alcohol were calculated and the drinking characteristics of the respondents are presented by age, sex, marital status, social class, accommodation and occupation. The contribution that such community surveys play in the development of local alcohol policy is discussed.

Measurement of hemoglobin chains bound to the erythrocyte membrane. Development of a method and studies of incubated normal cells.

A method utilizing sodium dodecyl sulfate--polyacrylamide gel electrophoresis for the sepration of the alpha and beta chains of hemoglobin has been adapted to quantify hemoglobin chains by simultaneous electrophoresis of globin standards with unknowns, staining with Coomassie blue, densitomeric scanning, and planimetry. This method has been used to quantify the globin chains bound to the human red cell membrane during sterile incubation and ATP depletion in vitro. In thoroughly washed (6-step) ghosts of incubated cells; (1) more beta than alpha chains were bound (beta/alpha ratio 1.28); (2) only about one third of the bound chains contained heme; and (3) globin accounted for less than 20% of the "excess" protein present in the incubated cells compared to fresh cells. Four-step ghosts contained more hemoglobin, a smaller proportion of heme-free alpha and beta chains, and approximately equal numbers of alpha and beta chains (beta/alpha ratio 1.09).

Studies on platelet plasma membranes. III. Membrane glycoprotein loss from circulating platelets in rabbits: inhibition by aspirin-dipyridamole and acceleration by thrombin.

DD125ISA, which binds to platelet surface glycoproteins, is lost more rapidly from double-labeled circulating rabbit platelets than is 51Cr, a label of platelet cytoplasm. Treatment of rabbits with aspirin and dipyridamole to diminish platelet function did not affect 51Cr survival but inhibited DD125ISA loss so that it disappeared from the circulation at the same rate as 51Cr . Intravenous thrombin infusion increased DD125ISA loss relative to 51Cr loss. Therefore surface glycoprotein loss was prevented by agents which inhibit platelet function and was accelerated by intravascular coagulation. These observations support the hypothesis that platelet surface glycoprotein loss is a continuous process in the normal circulation which may occur during reversible contact interactions in the process of hemostasis and thrombosis.

Studies on platelet plasma membranes. I. Characterization of surface proteins of human platelets labeled with diazotized (125i)-diiodosulfanilic acid.

A polar, nonpenetrating compound of high specific activity, diazotized (125I)-diiodosulfanilic acid (DD125ISA), has been developed as a label for exposed proteins of the human platelet plasma membrane, and platelet proteins and the pattern of labeling have been studied with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). That DD125ISA binds specifically to membrane proteins was demonstrated by: (1) the specific activity of isolated membrane protein was five to seven times that of whole platelet protein and (2) no proteins of intact platelets were labeled which were not represented in the isolated plasma membrane. That the DD125ISA-labeled membrane proteins were exposed on the cell surface was demonstrated by: (1) DD125ISA-labeled proteins were altered by trypsin treatment of intact, labeled platelets and (2) the pattern of labeling produced by reaction of isolated membranes with DD125ISA was quite different from that produced by the labeling of intact platelets. Analysis of platelet membrane proteins by SDS-PAGE demonstrated the glycoproteins previously described at 150,000 daltons (termed glycoprotein I) and 92,000 daltons (glycoprotein III) but we could discriminate two apparently distinct glycoproteins in the intermediate region (IIa: 125,000 daltons, and II: 118,000 daltons). Glycoproteins I and III were constant whereas IIa was clearly visible only in unreduced samples and II was predominant in reduced samples. Reaction of DD125ISA with intact platelets resulted in equal labeling of three of these four membrane glycoproteins (IIa, II, and III). The pattern of exposed proteins on the platelet surface labeled by DD125ISA was different from lactoperoxidase-131I, which labeled predominantly the 92,000 dalton glycoprotein, as demonstrated by simultaneous SDS-PAGE analysis. Therefore three glycoproteins of the human platelet plasma membrane are exposed to a radioisotope probe on the platelet surface and are accessible for contact interactions.

Studies on platelet plasma membranes. II. Characterization of surface proteins of rabbit platelets in vitro and during circulation in vivo using diazotized (125i)-diiodosulfanilic acid as a label.

Diazotized (125I)-diiodosulfanilic acid (DD125ISA) binds specifically to the exposed proteins on the surface of the rabbit platelet plasma membrane. This was demonstrated by the following observations with the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of whole platelets and the isolated plasma membrane fraction: (1) the specific activity of isolated membrane protein was sevenfold that of whole platelet protein, (2) no proteins of intact platelets were labeled which were not represented in the isolated plasma membrane, (3) DD125ISA-labeled proteins were altered by trypsin treatment of intact, labeled platelets, and (4) the pattern of labeling produced by reaction of isolated membranes with DD125ISA differed from that produced by the labeling of intact platelets. Reaction of DD125ISA with intact platelets produced labeling of only the three membrane glycoproteins (molecular weights: 180,000, 125,000, and 92,000 daltons) with greatest labeling of the largest glycoprotein and least labeling of the smallest glycoprotein. When rabbit platelets were labeled simultaneously with DD125ISA and 51Cr, the two isotopes were similarly distributed in various density populations of platelets. Some DD125ISA was solubilized from labeled and washed platelets by sonication, but all platelet DD125ISA was recovered in the plasma membrane fraction after 30 minutes' circulation in vivo. In vivo 51Cr recovery and survival were not altered by simultaneous labeling of platelets with DD125ISA. The disappearance of DD125ISA from circulating platelets (T 1/2 = 17 hours) was more rapid than 51Cr (T 1/2 = 30 hours) and appeared exponential in contrast to the linear 51Cr disappearance. On the other hand, DD125ISA did not disappear from platelets faster than 51Cr when doubly labeled platelets were harvested after 3 hours' circulation and incubated in autologous plasma (T 1/2 of DD125ISA elution = 43 hours, 51Cr = 33 hours). SDS-PAGE analysis of DD125ISA-labeled platelets after 14 to 20 hours' circulation in vivo demonstrated the same pattern of DD125ISA distribution on membrane glycoproteins as on the platelets prior to infusion. We interpret this symmetrical loss of the membrane label to indicate symmetrical loss of membrane proteins, suggesting that the platelet may lose pieces of membrane and not specific surface proteins during circulation. This could occur during reversible adhesion encounters during the process of hemostasis and cause the smaller size and decreased effectiveness of older platelets.