Determination of carcinogenic tobacco-specific nitrosamines in mainstream smoke from U.S.-brand and non-U.S.-brand cigarettes from 14 countries.

Tobacco-specific nitrosamines (TSNAs) comprise one of the major classes of carcinogenic compounds in mainstream cigarette smoke. As part of collaborative efforts between the World Health Organization and the U.S. Centers for Disease Control and Prevention (CDC) to reduce tobacco use and resulting disease, the CDC examined carcinogenic TSNA levels from cigarettes obtained from selected countries around the world. Using a modern, high-throughput liquid chromatography/mass spectrometry/mass spectrometry method under stringent quality control protocols, we determined the carcinogenic TSNA levels in mainstream smoke from a globally marketed brand, Marlboro, and from local top-selling cigarette brands from 14 countries. The levels of carcinogenic TSNAs in mainstream smoke collected using a 35-ml puff volume, 60-s puff interval, and 2-s puff duration correlated well (R=0.79, p<.0001) with previously reported levels in the corresponding tobacco filler. Marlboro cigarettes purchased in 10 countries had significantly higher carcinogenic TSNA levels in mainstream smoke than did local-brand cigarettes from the same country. In only one country, Brazil, were the carcinogenic TSNA levels in mainstream smoke from Marlboro cigarettes significantly lower than in the locally popular brand. However, carcinogenic TSNA levels in mainstream smoke from Brazilian Marlboro cigarettes were usually lower than those in mainstream smoke from the Marlboros purchased in the other 13 countries, suggesting a reason for the difference. The wide range of mainstream smoke carcinogenic TSNA levels measured in the present study (8.7-312 ng/cigarette) suggest that manufacturers can lower the carcinogenic TSNA levels and that, for similar filter ventilation, carcinogenic TSNA levels in the tobacco filler of a cigarette are a useful indicator of the corresponding levels in mainstream smoke.     

白肋烟烟碱转化及烟草特有亚硝胺形成

从烟草特有亚硝胺形成的化学,烟草特有亚硝胺与前体物的关系,调制过程、贮藏过程中烟草特有亚硝胺的形成,遗传改良降低烟碱转化和烟草特有亚硝胺,生物技术抑制烟碱转化降低烟草特有亚硝胺等方面综述了最新研究进展.     

Confirmatory factor analysis of the Nicotine Dependence Syndrome Scale in an American college sample of light smokers.

The five-factor structure of the Nicotine Dependence Syndrome Scale (NDSS) obtained with samples of mature, heavy smokers has not been replicated in samples of younger, less experienced smokers. Furthermore, the idea that the interrelationships among the NDSS factors are best explained by a single higher-order factor (nicotine dependence) has not been evaluated empirically. This study examined the first- and second-order factor structure of the NDSS in a first-year college sample of light smokers (N = 154). NDSS measures completed at the end of the first semester of college were analyzed using confirmatory factor analysis. The hypothesized five-factor model provided adequate fit to the data. The second-order factor model did not fit the data as well as the correlated first-order factor model, suggesting that an overarching dependence factor may not account for the interrelationships among the five first-order factors. This study provided support for the multidimensional structure of the NDSS among a first-year college sample of light smokers.     

Metabolic changes in blood and liver of dairy cows during either feed restriction or administration of 1,3-butanediol.

Previous research has shown that a combination of feed restriction and dietary 1,3-butanediol starting at 14 d post-partum resulted in fatty liver and ketosis. Sixteen multiparous Holstein cows were used to determine effects of feed restriction or 1,3-butanediol as separate treatments. Treatments during d 14 to 42 postpartum were 1) control (ad libitum intake), 2) 20% feed restriction, or 3) control plus dietary 1,3-butanediol (5.5% of DM). From d 43 to 56, cows assigned to treatments 2 and 3 received a combination of feed restriction and butanediol. One cow on treatment 2 developed ketosis, but not fatty liver, after only 4 d of feed restriction. No other cows developed fatty liver or ketosis. Both treatments decreased milk production compared with controls. Feed restriction increased the extent of negative energy balance and caused transient increases in concentrations of NEFA, acetate, and beta-hydroxybutyrate in plasma. Concentrations of beta-hydroxybutyrate and insulin in plasma were increased by butanediol, which is a potent ketone body precursor. Concentration of glycogen in liver was less in feed-restricted cows, whereas glycogen and total lipid were greater in cows given butanediol separately. Gluconeogenic capacity of liver slices was not different among groups. Addition of 1,3-butanediol to in vitro incubation media decreased oxidation of propionate to CO2. Neither feed restriction nor dietary 1,3-butanediol as separate treatments induced the fatty liver and ketosis observed in earlier experiments in which the two treatments were given together.     

Acute nicotine fails to alter event-related potential or behavioral performance indices of auditory distraction in cigarette smokers.

Behavioral studies have shown that nicotine enhances performance in sustained attention tasks, but they have not shown convincing support for the effects of nicotine on tasks requiring selective attention or attentional control under conditions of distraction. We investigated distractibility in 14 smokers (7 females) with event-related brain potentials (ERPs) and behavioral performance measures extracted from an auditory discrimination task requiring a choice reaction time response to short- and long-duration tones, both with and without embedded deviants. Nicotine gum (4 mg), administered in a randomized, double-blind, placebo-controlled crossover design, failed to counter deviant-elicited behavioral distraction (i.e., slower reaction times and increased response errors), and it did not influence the distracter-elicited mismatch negativity, the P300a, or the reorienting negativity ERP components reflecting acoustic change detection, involuntary attentional switching, and attentional reorienting, respectively. Results are discussed in relation to a stimulus-filter model of smoking and in relation to future research directions.     

Incomplete compensation does not imply reduced harm: yields of 40 smoke toxicants per milligram nicotine in regular filter versus low-tar cigarettes in the 1999 Massachusetts Benchmark Study.

The yields of 40 toxic smoke constituents per mg nicotine were computed in three matched pairs of higher- and lower-tar cigarettes tested in the 1999 Massachusetts Benchmark Study. In the three pairs, 19, 20 and 17 compounds, respectively, exhibited significantly greater yields per mg nicotine in the lower-tar than the corresponding higher-tar brand. Based on the assumption that toxicant yields per mg nicotine were independent of smoking intensity, the minimum degree of nicotine compensation necessary to obtain equal or greater dosages of these toxic compounds from the lower-tar cigarette ranged from 0% to 73%. A smoker who compensates only incompletely for nicotine may thus obtain a higher dosage of a specific smoke toxicant from a lower-tar cigarette than from a higher-tar cigarette. From the toxicological standpoint, incomplete compensation for nicotine does not necessarily translate into harm reduction.     

Transpiration efficiency and carbon-isotope discrimination of grapevines grown under well-watered conditions in either glasshouse or vineyard

This paper describes variation in transpiration efficiency ‘W’ (where W = dry matter produced/water transpired) among grapevine genotypes grown under well‐watered conditions in either a glasshouse or a vineyard. Nineteen genotypes were grown in a glasshouse where growth and transpiration were measured. W ranged from 2.5 to 3.4 g dm/kg H₂O transpired. Carbon‐isotope discrimination (Δ) of laminae dry matter ranged from 20.8 to 22.7%o and there was a negative relationship (R²= 0.58) between W and Δ. A large proportion of variation in W could be attributed to variation in stomatal conductance. Genotypic variation in photosynthetic capacity was also an important component of variation in W. In a second experiment, lamina Δ was measured for mature field‐grown Shiraz and Chardonnay, grown either on their own roots or grafted to five different rootstocks, and maintained at three sites under well‐watered conditions. At all sites and regardless of rootstock, the laminae of Chardonnay had Δ values 1 to 2%o lower than Shiraz. There was also a 1 to 2%o variation among the sites. Rootstock variety affected Δ values inconsistently and by a maximum of 0.5%o. Leaf gas exchange measurements were performed at a single site on sun‐exposed leaves of Chardonnay and Shiraz on either their own roots or 1103 Paulsen, a moderate to high vigour rootstock. There was no significant effect of rootstock on leaf gas exchange and photosynthetic rates did not differ between scion varieties. However, Chardonnay had a 20% lower stomatal conductance and a 1.4‐fold higher ratio of CO₂assimilation/H₂O transpiration (A/T) indicating a potentially higher W, at a leaf level, for Chardonnay compared with Shiraz. We conclude that photosynthetic capacity was also higher for Chardonnay. Δ values, predicted from the C_i/C_a ratio calculated from leaf gas exchange measurements, did not differ significantly from measured values for laminae Δ. This similarity for Δ, in conjunction with the fact that the lower Δ of Chardonnay was reflected in a higher A/T ratio, suggests that Δ may be a reliable predictor of comparative W under vineyard conditions.     

A search for differences in size perception of near objects in young myopes corrected by either spectacles or contact lenses.

Accommodation and convergence demands are lower for a spectacle-corrected myope than for the same individual when corrected with contact lenses. Thus the impact of accommodative/convergence micropsia ought to be lower with the spectacle correction. A size-matching experiment which required myopic subjects (corrections up to -12.25 D) to match the sizes of each of four standard targets with a variable comparison target was therefore conducted. The standard targets were placed at four viewing distances: 3 m, I m, 0.5 m and 0.25 m. All standard targets subtended 2 degrees at the eye. The variable comparison target was situated at a fixed distance of 2 m and was generated on a visual display unit. Each of the eight subjects was shown one standard target at a time under binocular viewing conditions and was told to adjust the size of the comparison target until he/she felt that both targets were equal in linear size. Two sets of readings were taken: one when the subject's myopia was corrected with spectacles and one when corrected with contact lenses. No systematic difference in size perception was found between the spectacle and contact lens corrected cases, implying that the relatively small differences in accommodation and convergence demand did not significantly influence the size judgements.     

Comparison of semen quality in young and mature Holstein bulls measured by light microscopy and flow cytometry

Random samples of cryopreserved, milk-extended semen, collected from 20 Holstein bulls at about 14 mo of age (young) and again at about 4 yr of age (mature), were evaluated at thawing and during 3-h incubation to compare semen quality of young versus mature bulls. Evaluation by differential interference contrast microscopy showed greater proportions of cytoplasmic droplets in semen from young versus mature bulls. Mature bulls exhibited greater proportions of intact acrosomes in freshly thawed semen than did young bulls. Evaluation of sperm chromatin structure by flow cytometry after staining with acridine orange showed lower values for mature versus young bulls, indicating resistance of DNA in nuclear chromatin to acid denaturation increased with age. Correlations between ages for most sperm morphology, acrosome integrity, and flow cytometry variables were high and positive. Nonreturn rate for young bulls was positively related to morphologically normal sperm and acrosomal integrity and negatively related to flow cytometry traits. Results suggest semen quality of young bulls was related to subsequent quality as mature bulls. With flow cytometry, differences were detected between semen samples that were not evident with light microscopy.     

Long-term changes in sleep and depressive symptoms of smokers in abstinence.

Few studies have evaluated the impact of smoking cessation on objective measures of sleep. The present study assessed the long-term effects of tobacco smoking abstinence on sleep and depression. A total of 15 chronic smokers with Hamilton Rating Scale for Depression (HAM-D) scores of less than 9 were evaluated. Subjects were screened for baseline data when they were smoking chronically. They underwent a 5-week psychological treatment for tobacco smoking, after which their depressive symptoms and sleep architecture were evaluated at 1, 2, 4, 6, 9, and 12 months of abstinence. We report the results of the seven patients who completed 1 year of evaluations and of those patients who achieved only partial abstinence. Polysomnographic recordings were taken, level of depression was measured with the HAM-D, and urinary cotinine levels also were evaluated. HAM-D scores were analyzed with and without sleep items. Nicotine abstinence reduced latency to rapid eye movement (REM) sleep and increased HAM-D scores, suggesting that chronic smokers have depressive symptoms that may be controlled by nicotine administration.     

Molecular and microbiological analysis of caecal microbiota in rats fed with diets supplemented either with prebiotics or probiotics

The potential health-improving effects of both a prebiotic and a probiotic infant formula have been evaluated in a rat model. Two groups of 10 rats were fed with either prebiotics containing fructo-oligosaccharides or probiotics containing viable Bifidobacterium lactis and Streptococcus thermophilus. The composition of their caecal microbiota was analyzed both by classical plate count of the main bacterial groups and by PCR amplification of a V3 fragment of 16S rRNA genes and denaturing gradient gel electrophoresis (DGGE). Both diets induced a significant reduction of clostridia and Bacteroides spp. compared to a control diet, whereas prebiotics were also able to reduce the number of coliforms and to increase the presence of bifidobacteria. DGGE analysis showed a significant increase of 16S rRNA gene fragments in rats fed with either probotics or prebiotics. Nineteen bands were sequenced and most of them showed similarity to cultured bacteria. Detection of Bifidobacterium spp. by this technique using genus-specific primers only permitted these bacteria to be detected in prebiotics-fed rats, whereas the use of Lactobacillus group-specific primers gave similar results in rats fed with any diet, in agreement with the plate count results.     

Carbon and nitrogen partitioning in either fruiting or non-fruiting grapevines: effects of nitrogen limitation before and after veraison

Fruit effects on carbon (C) balance between reproductive and vegetative growth, and between shoots and roots, were studied under low versus high nitrogen (N) availability before and after veraison. Fruiting vines were compared with non-fruiting vines, and N was supplied at either a low or high rate, and either continuously or as a split application before and after veraison. In non-fruiting grapevines, leaf growth was greatly affected by N supply, but root growth was little affected. Low N supply before veraison favoured berry development, whereas after veraison enlarging fruits were disadvantaged by low N supply. Fruit growth was highly competitive with root growth, particularly before veraison, when N supply was low. Whole plant C and N accumulation rates were lower in fruiting plants. Berry amino acid content was influenced by all combinations of N treatments. Overall, fruit development was favoured by ensuring a low N supply rate before veraison, but this occurred at the expense of root growth as well as C and N uptake by the grapevines. After veraison, fruit can express a high sink strength if N is made available, probably because photosynthetic activity increases. These results provide new insights into how N may be managed in order to control grapevine C partitioning, to encourage berry development, and to sustain overall C and N uptake by grapevines.     

Relationships between dietary fatty acid composition and either melting point or fatty acid profile of adipose tissue in broilers

Data on the fatty acid composition of the diet and that of the adipose tissue in broilers were collected from the literature. The linear regression between the dietary and the adipose tissue unsaturated to saturated fatty acids ratio (U/S ratio) was calculated because the U/S ratio of adipose tissue fat determines its melting point, which is an indicator of the consistency of poultry fat. For 54 data points from three different experiments, the linear correlation coefficient of the relationship between dietary and adipose tissue U/S ratio was 0.77. The regression equation for linoleic acid in adipose tissue as a function of dietary linoleic acid was calculated. The linoleic acid content of adipose tissue was expressed as weight percentage of total fatty acids. Intake was expressed as either weight percentage of total fatty acids or as energy percentage of total dietary metabolizable energy. The linear correlation coefficients were 0.68 and 0.78 as based on 116 or 91 data points from 15 or 12 different experiments. Significant correlations were also found for α-linolenic acid. The linoleic acid content of adipose tissue was found to be correlated (r=0.87) for 25 data points with that in consumable broiler meat, which may affect serum cholesterol concentrations in humans. With the help of the regression formulas presented it may be possible to formulate broiler diets in relation to consumer health and product quality.     

Bacterial populations on teat ends of dairy cows housed in free stalls and bedded with either sand or sawdust

The main objectives of the experiment were: 1) to compare bacterial populations of mastitis-causing organisms on the teats of lactating dairy cattle housed on sand and sawdust bedding and, 2) to examine the relationship between bacterial counts present in the 2 bedding types with those on teat ends. Sixteen lactating Holstein cows were housed on either sand or sawdust-bedded free stalls using a crossover design with 3 wk per bedding type. Bedding samples were collected on d 0 (prior to animals lying on the bedding), 1, 2, and 6. Teat ends were sampled prior to the morning milking on d 1, 2, and 6. All samples were analyzed to determine coliform, Klebsiella spp., and Streptococcus spp. populations. There were 2 times more coliforms and 6 times more Klebsiella bacteria on teat ends of cows housed on sawdust compared with those housed on sand. In contrast, there were 10 times more Streptococcus spp. bacteria on teat ends of cows when housed on sand compared with sawdust. In both sawdust and sand bedding, coliforms, Klebsiella and Streptococcus counts increased over each experimental week, although patterns varied with bedding and bacteria type. Bacterial counts on teat ends were correlated with bacterial counts in sawdust (r = 0.47, 0.69, and 0.60 for coliforms, Klebsiella spp., and streptococci, respectively) and in sand (r = 0.35 for coliforms and r = 0.40 for Klebsiella spp.). In conclusion, coliforms and Klebsiella spp. on teat ends were more numerous when cows were housed on sawdust bedding, but Streptococcus spp. were more numerous on teat ends of cows housed on sand.     

Short communication: Glucose and fructose concentrations and expression of glucose transporters in 4- to 6-week pregnancies collected from Holstein cows that were either lactating or not lactating

Glucose is an essential nutrient for the conceptus. The objective was to determine if lactation affected the amount of glucose crossing the placenta by measuring glucose and fructose in placental fluids in lactating and nonlactating cows. Holstein cows were assigned to one of 2 treatments immediately after parturition [lactating (n=23) or nonlactating (dried off immediately after calving; n=20)]. Pregnant cows were slaughtered at one of 3d of pregnancy (d 28, 35, or 42) and tissues were collected. Plasma glucose and insulin were less in lactating cows. Pregnancies collected from lactating cows had less glucose and fructose in placental fluids compared with those from nonlactating cows. Relative to endometrium, the placenta expressed greater amounts of the glucose transporters SLC2A1 (Glut1), SLC2A3 (Glut3) and SLC2A4 (Glut4) mRNA. The mRNA for SLC2A1 decreased whereas the mRNA for SLC2A4 increased from d 28 to d 42 of pregnancy. Stepwise regression analyses for fetal and placental weight (dependent variable) retained day of pregnancy and maternal plasma insulin concentrations in the final model. The conclusion is that lower blood glucose and insulin in lactating cows may lead to less glucose crossing the placenta and slower fetal development during lactation. The slower fetal development may predispose lactating cows to fetal loss if developmental milestones are not reached.     

Effect on weaner pig performance and diet microbiology of feeding a liquid diet acidified to pH 4 with either lactic acid or through fermentation with Pediococcus acidilactici

The effect of feeding newly weaned pigs acidified liquid diets was investigated. The control diet was acidified to about pH 4 with lactic acid (LA). A second diet of the same formulation was acidified to about pH 4 by fermentation with Pediococcus acidilactici (PA). Forty‐eight weaner pigs (weight 7 kg±1 kg, age 24±4 days) were allocated to the two dietary treatments according to a randomised block design and fed ad libitum for 28 days. Food intake, daily gain and water intake were recorded, and a microbial assessment of the liquid diet was conducted. Reducing pH<4.0 in either of the liquid diets was effective in eliminating coliform bacteria. There were no significant differences in any of the performance parameters measured. The average daily liveweight gain overall was 474 and 496±17.8 g d⁻¹ for PA and LA, respectively, with a feed conversion ratio overall of 1.15 and 1.11±0.025 for PA and LA, respectively. Fermentation of liquid diets for newly weaned piglets could provide a more cost effective means of acidifying diets than the use of organic acids. Reducing the pH of the liquid diet to 4.00 by fermentation with Pediococcus acidilactici was a cost effective method of eliminating enteropathogens and spoilage organisms from the diet. © 1999 Society of Chemical Industry