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Biomedical subjects

M A Russell

Publications and source records attributed to M A Russell.

At least 91 records · Page 5Linked to original sources
PubMed1988

Elimination of cotinine from body fluids: implications for noninvasive measurement of tobacco smoke exposure.

Cotinine elimination from plasma, saliva, and urine was studied over 11 days in five subjects (three nonsmokers and two occasional smokers). Half-lives for cotinine averaged 16-19 hours in the different body fluids (range 10 to 27 hours between subjects). There was no tendency for the half-life in saliva to be longer than in plasma or urine. We conclude that choice of body fluid for cotinine assay in smoking studies should depend on practical rather than pharmacokinetic considerations.

Adult↗
PubMed1987

District programme to reduce smoking: effect of clinic supported brief intervention by general practitioners.

By encouraging and supporting general practitioners to undertake brief intervention on a routine basis smokers' clinics could reach many more smokers than are willing to attend for intensive treatment. In a study with 101 general practitioners from 27 practices 4445 cigarette smokers received brief intervention with the support of a smokers' clinic, brief intervention without such support, or the general practitioners' usual care. At one year follow up the numbers of smokers who reported that they were no longer smoking cigarettes were 51 (13%), 63 (9%), and 263 (8%), respectively (p less than 0.005). After an adjustment was made for those cases not validated by urine cotinine concentrations the respective success rates were 8%, 5%, and 5%. Use of nicotine chewing gum was associated with higher self reported success rates. General practitioners providing supported brief intervention encouraged not only more smokers to use the gum but also more effective use; gum users in this group reported a success rate of 27% at one year. Compliance by the general practitioners in recording smoking state averaged 45%, and significantly higher success rates were reported by patients whose smoking state had been recorded. Brief intervention by general practitioners with the support of a smokers' clinic thus significantly enhanced success rates based on self reports. Better results might be obtained if general practitioners' compliance with the procedure could be improved and if they encouraged more of their patients to try nicotine gum. Collaboration of this kind between a smokers' clinic and local general practitioners could deliver effective help to many more smokers than are likely to be affected if the two continue to work separately.

Adult↗
PubMed1987

Nicotine replacement in smoking cessation. Absorption of nicotine vapor from smoke-free cigarettes.

Nicotine replacement is a promising new approach to aid smoking cessation, and various methods of delivery are being developed. One new device is a smoke-free cigarette (Favor) that has been test-marketed in several US states. Without lighting up, it delivers nicotine vapor and is free of other harmful products of tobacco smoke. To examine its therapeutic potential, we measured plasma nicotine concentrations before, during, and after its use in eight male subjects. Very little nicotine was absorbed when it was puffed like a conventional cigarette. However, with an intensive schedule of puffing at four further smoke-free cigarettes over a 20-minute period, plasma nicotine concentrations were increased by an average of 17.3 ng/mL (107.3 nmol/L) (range, 10.9 to 30.4 ng/mL [67.6 to 188.5 nmol/L]). Heart rate and blood pressure also increased significantly. The rate of nicotine absorption was slow and resembled that obtained from nicotine chewing gum, suggesting that most of the nicotine was deposited in the mouth, throat, and large airways and did not reach the lung alveoli. Despite the slow absorption, the plasma nicotine levels produced could be of therapeutic value as an aid to smoking cessation.

Absorption↗
PubMed1987

Cardiovascular and subjective effects of smoking before and after 24 h of abstinence from cigarettes.

Cigarette-induced changes in heart rate, skin temperature and subjective state were measured during the course of a normal smoking day and on smoking after 24 h abstinence in 21 smokers. Heart rate was not affected by smoking a test cigarette during the normal day's smoking, but after 24 h abstinence smoking a cigarette caused an average increase of 14 beats per min. Skin temperature, on the other hand, was reduced by smoking a cigarette under both conditions. Subjective effects of smoking were experienced only after the period of abstinence. The most common was dizziness, but nausea and other effects were also reported. Cigarette-induced changes in heart rate and skin temperature were positively correlated with each other, and the rise in heart rate after abstinence correlated positively with the strength of the subjective response. The results are discussed in terms of similarities and differences between different physiological systems in tolerance to the effects of nicotine.

Adult↗
PubMed1987

Estimation of smoke dosage and mortality of non-smokers from environmental tobacco smoke.

This paper shows how biochemical markers can be used to estimate smoke intake from passive smoking to complement epidemiological studies on the health risks and mortality to non-smokers. Using data from slow nicotine infusions given over 1 h, we estimated that the nicotine intake from passive smoking averages about 0.014 mg/h among urban non-smokers leading their usual daily lives. This compares with 0.23 mg/h in a smoke-filled public house, 0.36 mg/h during maximum exposure in an unventilated room, and 1.0 to 1.4 mg nicotine per cigarette taken in by active smokers. Data from several studies on urinary nicotine concentrations and those of cotinine in blood, urine and saliva were collated. The results show that the concentrations in non-smokers averaged about 0.7% (for nicotine) and 0.6% (for cotinine) of the levels found in smokers. From this we estimate that the mortality from passive smoking is about 1000 non-smokers per year in Britain and about 4000 per year in the United States, assuming that the relation of dose to risk is linear.

Carbon Monoxide↗
PubMed1987

Quantitative estimation of liver attenuation and echogenicity: normal state versus diffuse liver disease.

A method based on broad-band amplitude for obtaining attenuation and echogenicity estimates from homogeneous phantoms and tissues is described. Although a number of assumptions about the beam and scattering properties must be made, the attenuation results are as accurate as those obtained by the spectral-difference method and show less variability. The method was applied to the livers of 18 healthy volunteers and 76 patients with liver disease, including 29 patients with chronic hepatitis and 30 patients with Gaucher disease. Patients with chronic hepatitis formed a bimodal distribution, with one group having lower than normal attenuation and echogenicity values and another having elevated values. Six patients with type I glycogen storage disease and fatty infiltration of the liver had highly attenuating, echogenic livers as did patients with fatty livers from other causes. This finding confirms the subjective impressions already reported in the literature. In contrast to previous literature reports, patients with cirrhosis had normal attenuation and echogenicity values. Reasons for this discrepancy are discussed.

Gaucher Disease↗
PubMed1986

Do older children take in more smoke from their cigarettes? Evidence from carbon monoxide levels.

Expired-air carbon monoxide (CO) concentrations were measured in 125 pupils aged 11-17 years attending a girls' comprehensive school in the South of England who had smoked at least one cigarette on the day of testing. Both number of cigarettes smoked on the day of testing and time since the last cigarette were independently related to CO concentrations. Although there was a positive correlation between age and CO, this disappeared when number of cigarettes smoked on the day of testing and time since the last cigarette were taken into account. Previous reports of increasing CO concentrations with age taking account of cigarette consumption may be due to the use of usual daily cigarette consumption rather than number on the day of testing, which is more relevant given the short half-life of CO in the blood. In this sample, no evidence was found for an increase in smoke inhalation with increasing age.

Adolescent↗
PubMed1986

Predictors of outcome in a general practitioner intervention against smoking.

Analysis of baseline population characteristics in a large-scale (N = 1,328), controlled trial of general practitioner intervention against smoking (including advice and advice plus nicotine gum groups) revealed significant associations between the probability of abstinence at 4 months and sex, longest previous abstinence, dependence, motivation to quit smoking, and cigarette consumption. Women did less well overall, and dependence had a greater negative relationship to outcome among women than among men. The positive association of motivation was greater for higher levels of cigarette consumption. In the nicotine gum group, the negative dependence relationship was smaller than that in the other two groups (advice and control). Longest previous abstinence had a curvilinear relationship to outcome, the positive association diminishing as length of abstinence increased. Notwithstanding the above interactions, the gum offer was universally beneficial, except at the lowest levels of dependence, where it had little effect.

Adolescent↗
PubMed1986

Determination of cotinine in biological fluids of non-smokers by packed column gas-liquid chromatography.

A method is described for the analysis of cotinine in plasma, saliva and urine using packed-column gas-liquid chromatography, which is sufficiently sensitive and reproducible for quantitative study of the low levels resulting from exposure of non-smokers to other people's smoke. The lower limit of detection of cotinine in these fluids was 100 pg ml-1. The coefficient of variation over the range 0.25 to 2.0 ng ml-1 averaged 7.7%. In a sample of 85 non-smokers the concentrations of cotinine in plasma correlated 0.82 with those in urine and saliva, while the correlation between the saliva and urine concentrations was 0.91. Saliva cotinine concentrations were quantitatively related to passive exposure to parental smoking in a population study of 569 non-smoking schoolchildren.

Chromatography, Gas↗
PubMed1986

Reduction of tar, nicotine and carbon monoxide intake in low tar smokers.

Blood nicotine, cotinine, and carboxyhaemoglobin (COHb) concentrations were measured in 392 smokers (255 women and 137 men) of "middle tar" (17-22 mg), "low to middle" (11-16 mg), and "low tar" (less than 11 mg) cigarettes. Since tar intake cannot yet be measured directly, we devised an index to estimate it based on the use of measured levels of an intake marker (eg, blood nicotine) and the ratio of the tar to marker yields of the cigarettes. This approach was validated by its ability to enhance the prediction of levels of one marker by use of another. In a practical test, using COHb and the CO/nicotine yield ratio of the cigarettes, the mean blood nicotine concentration of the low tar smokers was predicted to be 31.9 ng/ml compared with the measured mean of 31.8 ng/ml. Our main findings were that despite substantial compensatory increases in inhalation, the low tar smokers took in about 25% less tar, about 15% less nicotine, and about 10% less carbon monoxide than smokers of middle and low to middle tar cigarettes. These results indicate that low tar cigarettes of the type available in Britain since the late 1970s are likely to prove less harmful than other brands. Monitoring of smoke intakes could supplement epidemiological approaches and provide earlier evidence of whether changing cigarette designs lead to any significant dosage reduction that could affect the risk of disease.

Carbon Monoxide↗
PubMed1986

Effect of meal schedules and fasting on selected plasma free amino acids in horses.

The effects of meal frequency and fasting on selected plasma free amino acids (PFAA) was studied in horses. Six 22-mo-old Quarter Horses were used in a replicated 3 X 3 Latin-square design in which each horse received one meal per day (1M), two meals per day (2M) or six meals per day (6M) for 2 wk. A complete pelleted ration was fed at a rate of 1.75% of body weight daily. The consumption of a meal by the horses fed 1M and 2M daily was followed by an increase (P less than .05) in plasma methionine. The highest levels were observed at 5 h and 3 h in the 1M and 2M treatments, respectively. The horses receiving the larger meal (1M) also had higher methionine levels. There were no significant changes in plasma methionine levels in the 6M group. Feed was withheld from the 1M group for 48 h and blood samples were obtained for alanine, glutamine, glutamate, lysine and leucine levels. These amino acids also peaked at 5 h, then declined through 19 to 25 h. During the last 24 h PFAA levels increased (P less than .05). Although glutamine and lysine appeared to level off at 49 h after the meal, alanine, glutamate and leucine were still increasing.

Amino Acids↗