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Biomedical subjects

M J Jarvis

Publications and source records attributed to M J Jarvis.

At least 19 recordsLinked to original sources
PubMed2000

Children's exposure to passive smoking in England since the 1980s: cotinine evidence from population surveys.

OBJECTIVE: To determine whether children's exposure to passive smoking has changed since the late 1980s. DESIGN: Cross sectional surveys of nationally representative samples of secondary school children carried out between 1988 and 1998 by Office for National Statistics. SETTING: England. SUBJECTS: Secondary school children aged 11-15. MAIN OUTCOME MEASURES: Salivary cotinine concentrations in non-smoking children. RESULTS: Cotinine concentrations in all non-smoking children almost halved between 1988 and 1998, from a geometric mean of 0.96 (95% confidence interval 0.83 to 1.11) ng/ml in 1988 to 0.52 (0.43 to 0.62) ng/ml in 1998. This reduction was largely due to reductions in exposure in children from non-smoking households and to decreases in the percentage of parents who smoked. Children living with mothers or fathers who smoked experienced little reduction in exposure. CONCLUSIONS: Exposure to passive smoking among children in England has approximately halved since the late 1980s. This reduction is partly explained by the fall in the percentage of both mothers and fathers who smoke and is also likely to reflect reductions of smoking in public places. However, there is only limited evidence that children from smoking households have experienced a reduction in exposure through parents' avoidance of smoking in their presence.

Adolescent↗
PubMed2000

Smoke intake among smokers is higher in lower socioeconomic groups.

OBJECTIVE: To analyse socioeconomic differences in serum thiocyanate concentrations among current smokers, and whether such differences persist after adjustment for the number of cigarettes smoked. SETTING: General population of six districts of the Czech Republic in 1992. PARTICIPANTS: 451 male and 282 female current smokers. MAIN OUTCOME MEASURE: Serum concentration of thiocyanate. RESULTS: There was a clear educational gradient in serum thiocyanate among male smokers; car ownership and crowding were not related to thiocyanate. Age adjusted mean concentrations in men with primary, vocational, secondary, and university education were 168.6, 158.2, 148.2, and 141.8 micromol/l, respectively (p for trend 0.032). Adjustment for the average daily number of cigarettes explained a part of this gradient. Socioeconomic differences in serum thiocyanate were not seen in women. CONCLUSION: The strong gradient in men suggests that smokers from lower socioeconomic groups have a preference for higher smoke intake and so may be more nicotine dependent. This finding, if confirmed, would have important implications for anti-smoking programmes.

Administration, Inhalation↗
PubMed1998

Variations in cotinine levels in smokers during and after pregnancy.

OBJECTIVE: To compare the antenatal and postnatal cotinine levels in smoking women after controlling for the differences in smoking practices. STUDY DESIGN: A paired comparison of two measurements of cotinine concentration was conducted in 40 smoking women voluntarily recruited in a prenatal education program held in La Fe Hospital, Valencia, Spain, during 1990 and 1991. Cotinine concentration was assayed by gas chromatography in samples of saliva obtained during and after pregnancy. The Wilcoxon matched-pairs test and multiple linear regression analysis were used. RESULTS: The cotinine per cigarette ratio during pregnancy (median 3.53 ng/ml per cigarette) was significantly lower than the ratio in the postnatal testing (median 9.87 ng/ml per cigarette). This difference persisted after allowing for differences in reported cigarette consumption. CONCLUSION: These findings suggest that the available equivalencies between cotinine level and nicotine intake obtained from adult nonpregnant populations cannot be directly applied during pregnancy.

Adult↗
PubMed1998

Nicotine absorption and dependence in unlicensed lozenges available over the counter.

AIM: To demonstrate the nicotine absorption and dependence potential from unlicensed nicotine containing lozenges. DESIGN: A single case report of dependence on nicotine lozenges, plus measurements of nicotine levels before and after consumption of eight nicotine lozenges over 2 hours in volunteers. SETTING: Hospital Smokers' Clinic. PARTICIPANTS: One male patient suffering from schizophrenia who had consumed 150 "Stoppers" lozenges per day for the previous 5 years, plus seven non-smoker volunteers. MEASUREMENTS: Blood nicotine concentration. FINDINGS: The patient's low expired carbon monoxide level (5 p.p.m.) and high plasma nicotine (32 ng/ml) and cotinine levels (947 ng/ml) were consistent with very heavy lozenge consumption. The non-smoker volunteers obtained nicotine concentrations of around 11 ng/ml by consuming eight Stoppers lozenges over 2 hours. Other brands of nicotine lozenges produced lower initial levels, but also produced delayed intestinal absorption and vomiting after food consumption. CONCLUSION: Nicotine lozenges are a potential aid to smoking cessation but their safety, efficacy and abuse potential remain to be properly evaluated.

Humans↗
PubMed1998

Maternal cotinine level during pregnancy and birthweight for gestational age.

BACKGROUND: Recent studies have found that cotinine is a better predictor of birthweight than the number of cigarettes smoked in pregnancy. In this paper we test this hypothesis and use cotinine to explore the effect of environmental tobacco smoke (ETS) on birthweight. METHODS: In all, 1254 white women were interviewed at booking, 28 and 36 weeks about the number and brand of cigarette smoked. Cotinine was assayed from blood samples taken on the day of interview. The outcome was birthweight for gestational age. RESULTS: There was good agreement between self-reported smoker/non-smoker status and maternal cotinine with 1.3% women mis-reported as non-smokers at booking, 0.6% and 1.8% mis-reported at 28 and 36 weeks respectively. Among smokers, cotinine was more closely related to birthweight than the number of cigarettes smoked at all three time points (r = -0.25 versus r = -0.16 at booking). A reduction in cotinine between booking and 28 weeks was associated with increased birthweight but the effect was not statistically significant. Among non-smokers the association between birthweight and cotinine was not statistically significant after adjusting for maternal height, parity, sex and gestational age. Difference in mean birthweight between non-smokers in the lower and upper quintiles of cotinine was 0.2% (95% CI: -2.4, 2.8). Pooling the results of 10 studies plus our own gave an estimated difference in mean birthweight between women unexposed and exposed to passive smoke of 31 g (95% CI: 19, 44). CONCLUSIONS: Cotinine is a better predictor of birthweight than the reported number of cigarettes smoked. If biochemical analysis is impossible, then self-reported smoking habit should be obtained prospectively using a structured approach. Any effect on birthweight of maternal passive smoking during pregnancy is small compared with the effects of maternal active smoking.

Adult↗
PubMed1998

Filter ventilation and nicotine content of tobacco in cigarettes from Canada, the United Kingdom, and the United States.

OBJECTIVES: The purpose was to determine filter ventilation and the nicotine content of tobacco and their contribution to machine-smoked yields of cigarettes from the United States, Canada, and the United Kingdom. METHODS: Ninety-two brands of cigarettes (32 American, 23 Canadian, and 37 British brands) were purchased at retail outlets in State College, Pennsylvania, United States, Toronto, Canada, and London, United Kingdom. A FIDUS FDT filter ventilation tester measured the percentage air-dilution from filter vents. High-pressure, liquid chromatography was used to measure the nicotine content of tobacco. Regression techniques were used to examine the contributions of tobacco nicotine content and filter ventilation to machine-smoked yields of tar, nicotine, and carbon monoxide (CO). RESULTS: Ninety-four per cent of the American brands, 91% of the Canadian brands, and 79% of British brands were ventilated. The total nicotine content of tobacco and percent nicotine (by weight of tobacco) averaged 10.2 mg (standard error of the mean (SEM) 0.25, range: 7.2 to 13.4) and 1.5% (SEM 0.03, range 1.2 to 2) in the United States, 13.5 mg (SEM 0.49, range: 8.0 to 18.3) and 1.8% (SEM 0.06, range: 1.0 to 2.4) in Canada, 12.5 mg (SEM 0.33, range: 9 to 17.5) and 1.7% (SEM 0.04, range: 1.3 to 2.4) in the United Kingdom. Multiple regression analyses showed that ventilation was by far the largest factor influencing machine-smoked yields of tar, nicotine, and CO. CONCLUSION: Filter ventilation appears to be the predominant method for reducing machine-smoked yields of tar, nicotine, and CO in three countries. However, some brands contain about twice as much nicotine (total content or percent nicotine) as do others, indicating that tobacco types or blends and tobacco castings can be used to manipulate nicotine content and nicotine delivery of cigarettes.

Canada↗
PubMed1997

Mood and physiological effects of subcutaneous nicotine in smokers and never-smokers.

This study compared the effect of subcutaneous nicotine injections (2 x 0.3 mg and 2 x 0.6 mg) with saline on subjective and physiological measures in 18 never-smokers and 18 smokers (24-h nicotine deprived), under conditions of rest and cognitive testing. Prior to the injections the mood of the smokers had deteriorated to a level significantly below that of the never-smokers as a result of tobacco withdrawal. Cognitive tests caused reductions in calmness and increased alertness but there was no evidence of nicotine improving mood in either group under either condition. The 0.6 mg dose worsened mood in never-smokers and caused unpleasant symptoms (e.g. dizziness and arm pain) in both groups. Compared with smokers, never-smokers experienced stronger symptoms of nicotine toxicity and a greater reduction in alertness in response to the 0.6 mg dose, suggesting chronic tolerance to some nicotine effects in smokers. Nicotine produced similar increases in heart rate and decreases in finger pulse volume in both groups. Our results imply that if nicotine has a mood enhancing effect it occurs only after tolerance has been acquired to its primary adverse effects, and that its ability to reverse the mood deterioration caused by tobacco withdrawal is susceptible to situational factors such as our experimental conditions.

Adult↗
PubMed1997

Smoking, alcohol consumption, and leukocyte counts.

Blood was collected from 684 healthy volunteers and examined for total and differential white blood cell (WBC) counts. A subgroup also was tested for numbers of T cells, B cells, and CD4 and CD8 subsets. Smoking status and alcohol consumption were determined by means of questionnaire, and smoking status was verified with serum cotinine concentration. High smoking rate was associated with increases in all counts. Former smokers abstinent less than 5 years still demonstrated elevated counts, whereas those abstinent more than 5 years had WBC counts comparable to those in persons who were never smokers. Compared with levels in those who had never smoked, total WBC counts were 27% higher in current smokers and 14% higher in former smokers who were abstinent for less than 5 years. Lymphocyte counts were 9% higher in those consuming more than one alcoholic drink per day than in those consuming less alcohol, but drinking was not associated with other cell populations.

Adult↗
PubMed1996

Relation of caffeine intake and blood caffeine concentrations during pregnancy to fetal growth: prospective population based study.

OBJECTIVES: To examine the association of plasma caffeine concentrations during pregnancy with fetal growth and to compare this with relations with reported caffeine intake. DESIGN: Prospective population based study. SETTING: District general hospital, inner London. SUBJECTS: Women booking for delivery between 1982 and 1984. Stored plasma was available for 1,500 women who had provided a blood sample on at least one occasion and for 640 women who had provided a sample on all three occasions (at booking, 28 weeks, and 36 weeks). MAIN OUTCOME MEASURE: Birth weight adjusted for gestational age, maternal height, parity, and sex of infant. The exposures of interest were reported caffeine consumption and blood caffeine concentration. Cigarette smoking was assessed by blood cotinine concentration. RESULTS: Caffeine intake showed no changes during pregnancy, but blood caffeine concentrations rose by 75%. Although caffeine intake increased steadily with increasing cotinine concentration above 15 ng/ml, blood caffeine concentrations fell. Caffeine consumption was inversely related to adjusted birth weight, the estimated effect being a 1.3% fall in birth weight for a 1,000 mg per week increase in intake (95% confidence interval 0.5% to 2.1%). The apparent caffeine effect was confined to cigarette smokers, among whom the estimated effect was-1.6%/1000 mg a week (-2.9% to -0.2%) after adjustment for cotinine and -1.3% (-2.7% to 0.1%) after further adjustment for social class and alcohol intake. Adjusted birth weight was unrelated to blood caffeine concentrations overall (P = 0.09, but a positive coefficient), after adjustment for cotinine (P = 0.73), or among current smokers (P = 0.45). CONCLUSIONS: Smokers consume more caffeine than non-smokers. Blood caffeine concentrations during pregnancy are not related to fetal growth, but caffeine intake is negatively associated with birth weight, with this effect being apparent only in smokers. The effect remains of borderline significance after adjustment for other factors. Prudent advice for pregnant women would be to reduce caffeine intake in conjunction with stopping smoking.

Beverages↗
PubMed1996

Effect of smoking cessation on cervical lesion size.

BACKGROUND: Cigarette smoking has been postulated as a cofactor in the aetiology of cervical cancer, but a causal role is difficult to establish because of potential confounding by sexual behaviour. We have investigated the effect of cessation or reduction of cigarette smoking on the course of minor-grade cervical lesions. METHODS: In this intervention study 82 women volunteers with minor-grade lesions on colposcopy (cervical intraepithelial neoplasia grade 1 or less) attempted to give up smoking for 6 months. Smoking histories were taken at 3-monthly clinic visits and verified by measurement of salivary cotinine concentrations. At each clinic visit, a photograph of the cervix was taken; the image was digitised and computer-aided image analysis was used to assess lesion size, by investigators unaware of smoking status. FINDINGS: Of the 82 women, 17 stopped smoking completely for at least 6 months and 11 others reduced their smoking consumption by more than 75%. Of these 28 women, 23 (82%) showed a reduction in lesion size of at least 20% or 4 mm2 compared with 13 (28%) of the 47 non-quitters (odds ratio 12.0 [95% Cl 3.9-32.7]). The remaining seven women had unconfirmed smoking histories. There was a significant correlation between the extent of smoking reduction and the change in lesion size (chi2 for trend=31.55, p<0.0001). Adjustment for social class, method of contraception, and stage of menstrual cycle did not affect the results. INTERPRETATION: Our findings support a link between smoking and cervical disease and suggest that smoking cessation could have a beneficial effect on early cervical abnormalities.

Adult↗
PubMed1996

The association between having children, family size and smoking cessation in adults.

This study aimed to examine the relationship between rates of smoking cessation in adults and whether or not they have dependent children at home. Previous work has suggested that among women, particularly poor women, caring for young children might work against giving up smoking, while the relationship between having children and giving up smoking in men is largely unexplored. The analysis employed data from 3 years (1988, 1990 and 1992) of the General Household Survey, and assessed rates of self-reported smoking cessation among adult ever-smokers of cigarettes aged 16-49 years. After adjustment for a wide range of potential confounding variables, adults with dependent children were more likely to have given up smoking than those without. Among women there was a linear increase in the odds of cessation with each additional child. Using the combined data from the 3 years, and by comparison with those with no children, the adjusted odds of cessation were 1.42 (95% CI 1.21-1.67) in women with one dependent child, 1.77 (1.50-2.09) in those with two and 2.19 (1.74-2.74) in those with three or more. The effect was marginally present in men, with an increase in the odds of cessation of about 25% in those with two or more dependent children. (Estimated odds from the combined data 1.30 (1.09-1.50) for men with two dependent children and 1.23 (0.97-1.51) for those with three or more.) The association of increased rates of smoking cessation with number of dependent children did not vary with level of deprivation. It is concluded that having children is associated with smoking cessation in parents, whether poor or affluent. Health education campaigns targeted at families with children could aim to amplify this effect.

Adolescent↗
PubMed1995

The scientific case that nicotine is addictive.

Despite the wide-ranging and authoritative 1988 review by the US Surgeon General, views questioning the addictiveness of nicotine contine to be expressed in some quarters. This lack of complete consensus is not unexpected, since no universally agreed scientific definition of addiction exists. In this paper we briefly consider a number of lines of evidence from both the human and animal literature bearing on the addictiveness of nicotine. Patterns of use by smokers and the remarkable intractability of the smoking habit point to compulsive use as the norm. Studies in both animal and human subjects have shown that nicotine can function as reinforcer, albeit under a more limited range of conditions than with some other drugs of abuse. In drug discrimination paradigms there is some cross-generalisation between nicotine on the one hand, and amphetamine and cocaine on the other. A well-defined nicotine withdrawal syndrome has been delineated which is alleviated by nicotine replacement. Nicotine replacement also enhances outcomes in smoking cessation, roughly doubling success rates. In total, the evidence clearly identifies nicotine as a powerful drug of addiction, comparable to heroin, cocaine and alcohol.

Animals↗