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At least 865 records · Page 48Linked to original sources

PubMed1989

Mathematics achievement of hearing impaired adolescents in different placements.

This study, involving 215 students and 63 teachers, addressed three concerns related to mainstreaming for hearing imparied students: the selection process, the difference between a mainstream placement with an interpreter and a self-contained placement, and the quality of the educational experience. Almost half of the variance in achievement between the two settings is described. Three conclusions can be drawn. First, student background factors are a primary determinant of achievement. Second, mainstreaming with an interpreter has no specific effect on achievement for hearing impaired students. Third, the quality of instruction is the prime determinant of achievement, regardless of placement.

Achievement↗

PubMed1977

Potential exposure from smoking parathion-contaminated cigarettes.

Pesticide workers usually contaminate their cigarettes with less than 100 microgram per cigarette by handling them, but in some instances such contamination has been found to be over 200 microgram. To obtain values for potential exposure resulting from smoking contaminated filter tip and nonfilter cigarettes, from 10 to 200 microgram of parathion was applied to the cigarette surface area found to be most often contaminated by hands. This was followed in two separate experiments by simulated smoking using a special apparatus to determine (1) passage of toxic material through cigarettes in mainstream smoke, (2) amount found in sidestream smoke, (3) amount trapped in the filter or equivalent butt end, and (4) amount recovered in ashes. The amount of parathion passing through cigarettes as a potential for inhalation exposure ranged up to 28% of dosing levels. No paraoxon or S-ethyl parathion was detected. Although there was an indication that slightly more pesticide was recovered from filters than from equivalent butt ends, the amount recovered in mainstream smoke of filter type cigarettes was not significantly lower than for nonfilter cigarettes. Location of contamination on a cigarette had minimal effect on the amount found in mainstream smoke.

Chromatography, Gas↗

PubMed1991

A quantitative approach to assessing intercellular communication: studies on cigarette smoke condensates.

Analyses of intercellular communication is useful for assessing the effects of chemical treatment on the function of mammalian cell membranes in vitro. The objective of this study was to quantify and compare the activity of mainstream cigarette smoke condensate (CSC) from tobacco-heating and tobacco-burning cigarettes on both the rate and total amount of intercellular communication in vitro. Lucifer yellow uptake and lactate dehydrogenase release assays were used to evaluate plasma membrane toxicity. Gap junction intercellular communication (GJIC) was determined by quantifying fluorescence redistribution after photobleaching (FRAP) following a 1-hr exposure to concentrations of CSCs which were not toxic to the plasma membrane. GJIC was quantified in rat hepatic epithelial cells (WB cells) and human skin fibroblasts (MSU-2 cells) synchronized in the G1 phase of the cell cycle. In each of the cell types tested, CSC from tobacco-heating cigarettes did not inhibit GJIC at concentrations, where CSC from tobacco-burning cigarettes significantly inhibited both the total amount and the rate of GJIC. These results indicate that mainstream smoke condensate of cigarettes which heat tobacco is less biologically active than mainstream smoke condensate of cigarettes that burn tobacco as determined by in vitro gap junction intercellular communication.

Animals↗

PubMed1984

Flow through a venous valve and its implication for thrombus formation.

To elucidate the possible connection between the flow patterns in the pockets of venous valves and thrombus formation, detailed studies of the behavior of model particles and red cells flowing through a venous valve have been carried out using isolated transparent dog saphenous veins containing two-leaflet valves, and cinemicrographic techniques. It was found that large paired vortices, located symmetrically on both sides of the bisector plane of the valve leaflets, were present in each valve pocket under physiological flow conditions. Particles continually entered the valve pockets from the mainstream, spending long periods of time describing a series of spiral orbits of decreasing diameter, while moving away from the bisector plane, and eventually left the vortex, rejoining the mainstream. With concentrated suspensions of red cells, it was found that another smaller counter-rotating secondary vortex, driven by the large primary vortex existed deep in each valve pocket. The concentration of red cells in this secondary vortex remained appreciably lower than that in the mainstream. In such regions, fluid circulated with extremely low velocities, thus creating a very low shear field which allowed red cells to form aggregates. The results suggest that in some pathological states, the valve-pocket vortices could act as automatic traps and generators of thrombi in a fashion similar to that previously demonstrated in an annular vortex formed downstream from a sudden tubular expansion.

Animals↗

PubMed1983

Cadmium concentrations in tobacco and tobacco smoke.

The amount of cadmium in tobacco depends on the variety and origin of the plant as well as on the analytical method used to determine cadmium. In the literature, cadmium concentrations in tobacco of between 0.5 and 5 ppm are reported. Modern German cigarette tobacco contains about 0.5-1.5 micrograms cadmium/cigarette. Of importance for the smoker is the amount of the metal in the mainstream smoke. The cadmium level in the mainstream smoke of modern cigarettes is reduced by means of filters and other construction features. The average Cd value of German filter cigarettes is less than 0.1 microgram/cigarette in mainstream smoke. An average daily intake of about 1 microgram cadmium by smoking 20 cigarettes can be calculated on the basis of an experimentally proved pulmonary retention rate of 50%. Pulmonary resorption rates relevant to uptake rates of cadmium by smoking are discussed. It can be assumed that cadmium uptake by smoking modern cigarettes has been reduced because of modifications in tobacco processing and cigarette construction in the last few decades.

Cadmium↗

PubMed1985

Human alpha-1-proteinase inhibitor is inactivated by exposure to sidestream cigarette smoke.

Direct exposure of human alpha-1-proteinase inhibitor (alpha 1PI) to sidestream cigarette smoke causes an initial, rapid loss of elastase inhibitory capacity followed by a slow, gradual loss of activity as the protein is incubated in the smoke-exposed aqueous buffer solution. The exposure used here gives a total of 40% inactivation using one cigarette. This biphasic pattern of inactivation is similar to the inactivation seen following the direct exposure of alpha 1PI to mainstream smoke. We suggest that although exposures to sidestream smoke by nonsmokers are generally lower than the exposures to mainstream smoke experienced by smokers, sidestream smoke has the potential to produce similar types of damage as mainstream smoke, including emphysema-like damage, and should not be regarded as innocuous.

Blood Proteins↗

PubMedDate not supplied

Sidestream end-tidal carbon dioxide monitoring during helicopter transport.

INTRODUCTION: End-tidal carbon dioxide (EtCO(2)) monitoring is standard of care for intubated patients. Sidestream technology also allows EtCO(2) monitoring in non-intubated patients. This is the first study to evaluate the feasibility of monitoring sidestream EtCO(2) on intubated and non-intubated patients during helicopter transport. SETTING: An air medical transport program serving two level 1 trauma centers. METHODS: In this prospective observational study, sidestream EtCO2 was monitored in 100 consecutive patients transported by helicopter. Flight nurses rated the difficulty posed by various factors of sidestream monitoring. An experienced flight nurse and a clinical engineer evaluated waveforms and EtCO(2) values. RESULTS: Only 1 of the 100 transported patients required a change from sidestream to mainstream EtCO(2) monitoring. Moisture was noted in the tubing of two patients, and one was changed to mainstream. Eleven patients had occluded nares but were not changed to mainstream monitoring. On a 5-point Likert scale, responses to statements regarding difficulty with length of tubing, patient tolerance, and interference with patient care produced mean scores of 0.5 (range, 0-3). Responses regarding difficulty securing the cannula yielded a mean score of 0.7 (range, 0-3). Of 1,685 (99%) recorded EtCO(2) values, 1,668 met pre-established criteria for "consistent." Alveolar plateaus were identified in 81 of 94 (86%) patient waveforms by the flight nurse and 73 of 94 (78%) patient waveforms by the clinical engineer. CONCLUSION: Sidestream EtCO(2) monitoring is feasible during air medical transport of both intubated and non-intubated patients. The mechanism was easy to use, and consistent numeric values and waveforms with alveolar plateaus were obtained in a large majority of readings.

Adolescent↗

PubMed2005

Analysis of complex mixtures--cigarette smoke.

Mainstream cigarette smoke is a complex mixture that is inhaled into the respiratory system. The physical characteristics and chemical composition of mainstream smoke are reviewed and briefly compared with that of sidestream smoke. Special attention is paid to ageing effects and artifact formation during the sampling and testing of cigarette smoke, with specific examples of artifact formation during sampling discussed (nitrogen dioxide, methyl nitrite, etc.). Historically, the generation of cigarette smoke for chemical and biological testing has been based on standard smoke generation procedures that are intended for product comparisons. More recently, emerging global regulations have called for alternative smoke generation methods, with emphasis on results relevant to conditions of product use, e.g., estimates of maximum smoke emissions. Strategies for establishing such alternative smoke generation methods are discussed and the potential effects of alternative smoking conditions on analytical accuracy and precision are addressed. Current regulatory requirements that include Hoffmann analyte analysis (i.e., constituents reported to be associated with the risks of cigarette smoking) are also summarized and the potential effect of alternative smoke generation methods on individual constituent yields considered. Finally, a limited critique of emerging regulation that relates to mainstream cigarette smoke measurements, including a discussion of recent WHO recommendations, is offered.

Complex Mixtures↗

PubMed2006

Cadmium, lead, and thallium in smoke particulate from counterfeit cigarettes compared to authentic US brands.

Smoking remains the leading cause of preventable disease in the United States. Exposure to tobacco smoke leads to cancer, heart and lung disease, and addiction. The origin of the tobacco and cigarette manufacturing practices of counterfeit cigarettes are unknown. Because toxic metals are incorporated into the tobacco lamina during cultivation, the ambient metal content of the soil could produce significant differences in metal levels in both the tobacco and smoke of counterfeit cigarettes. We compared mainstream smoke cadmium, thallium, and lead deliveries from counterfeit and authentic brands. Mainstream smoke levels of all three metals were far greater for counterfeit than the authentic brands, in some cases by an order of magnitude. Significant differences still existed even after normalizing mainstream smoke metal levels with nicotine delivery; the counterfeits typically delivered much higher levels of all three analytes. Our findings, based on 21 different counterfeit samples, suggest that counterfeit cigarettes potentially result in a markedly greater exposure to toxic heavy metals than authentic brands, even after correcting for differences in nicotine intake. In view of the unknown health risks associated with inhaling higher levels of toxic metals, it is prudent to minimize exposure to toxic substances whenever possible.

Cadmium↗

PubMed2003

The deaf child--challenges in management: a parent's perspective.

Diana Glover lives in Buckinghamshire, UK with her husband, Ray, and their three sons, William (21), Robin (19) and Benjamin (10). Robin and Benjamin are profoundly deaf. Ray also has a hearing loss, which is unconnected with the children's deafness. Diana is a trustee of the National Deaf Children's Society. Diana will compare Robin's experiences with those of Benjamin. She will show how difficult it was to obtain a diagnosis of Robin's deafness, in spite of her early anxieties about his hearing, and that this had a marked impact on Robin's speech and language acquisition. She will speak about the struggle she and Ray had to convince their Local Education Authority that Robin should move from mainstream schooling to a boarding school for the deaf at the age of 9. She will also express her current anxieties as Robin, who has only deaf friends, moves from Mary Hare Grammar School for the Deaf to mainstream Higher Education. Robin's experiences will be contrasted with Benjamin's diagnosis at 7 weeks and progress in mainstream education. Diana will also highlight some of the issues that she and Ray had to consider when they agreed that Benjamin should have a cochlear implant at the age of 2. It will be demonstrated that having one hearing and two deaf sons has a profound effect on relationships within the family and with professionals. Diana will show how she and Ray have learned that one can easily overlook the needs of a hearing sibling, and that it is equally important for deaf children to come to terms with their disability. She will summarise the difficult choices they have had to make over implantation, communication methods and schooling and demonstrate that, even within one family, the needs of deaf children are never the same.

Attitude to Health↗

PubMedDate not supplied

Characteristics of people living with HIV who use community-based services in Ontario, Canada: implications for service providers.

Community-based AIDS service organizations (CBAOs) direct services to multiple-needs people living with HIV/AIDS who are less likely to use mainstream health promotion services. As people live longer with HIV, the potential to enhance quality of life increases, yet little is known about who uses CBAOs or how this use affects other health and social services. This study of people living with AIDS in Ontario, Canada (n = 297) examined the demographic and health-related characteristics of people with AIDS who do and do not use CBAOs and their patterns of mainstream service utilization. It found that users of CBAOs were significantly less healthy, less able to sustain normal activities, and more often depressed. They reported physical disabilities significantly more often. Their quality of life was also lower along certain dimensions. They were significantly poorer and more reliant on government income supports. They consumed significantly more nonhospital health and social services and had significantly higher out-of-pocket costs. These results suggest CBAOs are being accessed appropriately by those most vulnerable. In an effort to strengthen CBAO capacity to recognize and address depression and physical health problems prevalent among their clients, links to other mainstream health promotion and social services is recommended.

Adaptation, Psychological↗

PubMed1984

Lung dynamics and uptake of smoke constituents by nonsmokers--a survey.

Models of smoke kinetics and lung dynamics of inhaled particles are discussed and compared with the available literature on mainstream and sidestream smoke particles. The literature search reveals a dearth of reliable information on the deposition of inhaled particulate tobacco smoke components in the human lung. Scanty results on mainstream smoke range from unexpectedly high deposits to values in line with predictions of conventional mathematical deposition models confirmed in tests with stable aerosols. For sidestream smoke, only one well-described experimental result is available. It is in agreement with established deposition probabilities. Experimental and theoretical estimates of relative particle deposition in the human lung range from some 10% for sidestream smoke particles to more than 80% for mainstream aerosol. This indicates a need for more, and better, experimental data.

Humans↗

PubMed1997

13-week inhalation toxicity study of menthol cigarette smoke.

Menthol is a common pharmaceutical, food and tobacco flavouring ingredient used for its minty characteristics and cooling effects. A 13-wk comparative nose-only smoke inhalation toxicity study was conducted using an American-style, cellulose acetate-filtered, non-menthol reference cigarette and a similarly blended test cigarette containing 5000 ppm synthetic l-menthol tobacco. Male and female Fischer 344 rats were exposed for 1 hr/day, 5 days/wk for 13 wk at target mainstream smoke particulate concentrations of 200, 600 or 1200 mg/m3, while control rats were exposed to filtered air. Internal dose biomarkers (blood carboxyhaemoglobin, serum nicotine and serum continine) indicated equivalent exposures were obtained for the two cigarettes. Effects typically noted in rats exposed to high levels of mainstream tobacco smoke were similar for both cigarette types and included reduced body weights (males slightly more affected than females), increased heart-to-body weight ratios and lung weights, and histopathological changes in the respiratory tract. Rats exposed to reference cigarette smoke displayed a dose-related increase in nasal discharge that was not observed in menthol smoke-exposed rats. All smoke-related effects diminished significantly during a 6-wk non-exposure recovery period. The results of this 13-wk smoke inhalation study indicated that the addition of 5000 ppm menthol to tobacco had no substantial effect on the character or extent of the biological responses normally associated with inhalation of mainstream cigarette smoke in rats.

Administration, Inhalation↗

PubMed2004

Providing Complementary and Alternative Medicine in primary care: the primary care workers' perspective.

BACKGROUND: The use of Complementary and Alternative Medicine (CAM) in primary care is growing, but still not widespread. Little is known about how CAM can/should be integrated into mainstream care. OBJECTIVES: To assess primary care health professionals' perceptions of need and of some ways to integrate CAM in primary care. METHOD: Questionnaire survey of primary health care workers in Northwest London. General Practitioners (GPs) were targeted in a postal survey, other members of the primary care team, such as district and practice nurses, were targeted via colleagues. The questionnaire assessed health care professionals' perspective on complementary medicine, referrals, ways to integrate complementary medicine into primary care and interest in research on CAM. RESULTS: Responses were obtained from 149 GPs (40% response rate after one reminder) and 24 nurses and 32 other primary care team members. One hundred and seventy-one (83%) respondents had previously referred (or influenced referral) for CAM treatments, the main reasons cited were: patients request (68%), conventional treatments failed (58%) and evidence (36%) (more than one reason could be given). Acupuncture and homoeopathy were the therapies for which patients were most frequently referred, followed by manual therapies. There was a significant interest in more training/information on CAM (66%). Only 12 respondents (6%) were against any integration of CAM in mainstream primary care. Most respondents felt that CAM therapies should be provided by doctors (66%) or other health professionals trained in CAM (82%). Twenty-six percent of respondents agreed with provision of CAM by non-state-registered practitioners. It was felt that the integration of CAM could lead to cost savings (70%), particularly in conditions involving pain, but also cost increases (55%) particularly in 'poorly defined conditions'. Fifty-six percent of respondents would consider participating in studies investigating CAM. The greatest interest was in acupuncture (41% of those who expressed an interest in research), homoeopathy (30%) and therapeutic massage/aromatherapy (26%). CONCLUSIONS: There is considerable interest in CAM among primary care professionals, and many are already referring or suggesting referral. Such referrals are driven mainly by patient demand and by dissatisfaction with the results of conventional medicine. Most of our respondents were in favour of integrating at least some types of CAM in mainstream primary care. There is an urgent need to further educate/inform primary care health professionals about CAM.

Adult↗

PubMed2001

Unconventional therapies for cancer and cancer-related symptoms.

A significant proportion of cancer patients try unconventional therapies and many use 'complementary' therapies, as adjuncts to mainstream care, for management of symptoms and to improve quality of life. A smaller proportion use 'alternative' therapies, which are typically invasive, biologically active, and commonly promoted as replacements for, rather than adjuncts to, mainstream therapy. Many alternative therapies, including high-dose vitamin C, the Di Bella regimen, and laetrile have been shown not to be effective. For others, such as metabolic therapy, evidence is extremely limited. Conversely, most complementary therapies are well studied and of proven benefit. There is evidence from randomised trials supporting the value of hypnosis for cancer pain and nausea; relaxation therapy, music therapy, and massage for anxiety; and acupuncture for nausea. Such complementary therapies are increasingly provided at mainstream cancer centres.

Anxiety↗

PubMed2004

Development of a method to assess cigarette smoke intake.

Tar and nicotine deliveries of cigarettes measured using current standardized smoking machine protocols provide poor estimates of smoke exposure. The characteristics of human smoking behavior vary considerably and differ from the rigid parameters used with current standardized smoking machine protocols. Current alternatives, including measurement of biomarkers, are invasive, time-dependent, and can be too expensive to be used as mechanisms for carrying out large-scale investigations required to help determine the influence of cigarette design on smoking behaviors. To obtain more reasonable estimates of mainstream smoke exposure, we developed a method to quantitatively measure solanesol, a naturally occurring component in tobacco that is deposited during smoking in the cigarette filter butt. Quantification of solanesol extracted from the filters using liquid chromatography and tandem mass spectrometry is efficient, rapid, and extremely reliable. We found that the amount of solanesol deposited in a cigarette filter is related to the mainstream smoke deliveries of tar and nicotine under a variety of smoking conditions. In addition, the amount of solanesol trapped in the filter remains stable at least 4 weeks after smoking. Measuring solanesol in cigarette filters as an exposure marker provides a noninvasive means to obtain reasonable estimates of mainstream tar and nicotine smoke deliveries under a wide variety of smoking conditions.

Automation↗

PubMed2003

Percent free base nicotine in the tobacco smoke particulate matter of selected commercial and reference cigarettes.

The available evidence suggests that most of the nicotine in mainstream tobacco smoke is in the smoke particle matter (PM) phase. Nicotine can exist in protonated and free base forms in the smoke PM, and alpha(fb) is the fraction of the PM nicotine that is in the free base form. Because only the free base form can volatilize from the smoke PM phase to the gas phase of an inhaled aerosol and because gaseous nicotine deposits rapidly in the respiratory tract (RT), the magnitude and rate of nicotine deposition in the RT will depend on alpha(fb). The types of values that alpha(fb) can assume in the PM of cigarette smoke aerosols have not been well-known. The conventional view has been that mainstream cigarette smoke PM contains relatively little free base nicotine so that the cigarette smoker must absorb nicotine mostly from deposited particles. A prior study concluded that because cigarette smoke is at "pH 5.3", there is very little free base nicotine in such smoke. A 1994 internal tobacco company document discusses the view that "smoke pH" values for cigarette smoke are "approximately 6.0". This work uses volatility-based measurements to provide determinations of equilibrium nicotine alpha(fb) values for mainstream smoke PM from selected cigarettes. The effective pH (i.e., pH(eff)) of the smoke PM from selected brands of commercial cigarettes was found to span a range of 6.0-7.8 (nicotine alpha(fb) = 0.01-0.36), with all pH(eff) values much larger than 5.3 and most larger than 6.0.

Nicotine↗

PubMedDate not supplied

Characteristics of and human influences on nitrogen contamination in Yellow River system, China.

Nitrogen (N) contamination in the Yellow River mainstream and its tributaries was studied using data from 1960 to 2000 from 312 monitoring sites in the Yellow River system. Data showed that N concentrations in the Yellow River have increased since 1960, especially after 1990. N concentrations in the Yellow River mainstream increased from the upper reaches (less than 1.0 mg L(-1) for TN and less than 0.10 mg L(-1) for NH4(+)-N) to lower reaches (higher than 4-5 mg L(-1) for TN and higher than 1.0 mg L(-1) for NH4(+)-N). However, the highest N contaminations (50-250 mg L(-1) for TN and 10-20 mg L(-1) for NH4(+)-N) was found in some tributaries, which was attributed as an effect of industrial wastewater and municipal sewage. Nitrogen concentrations from several monitoring sites were positively correlated with several regional socio-economic indices, such as population density, fertilization rates, livestock, industrial input and GDP. Depending on location, seasonal N concentrations contrasted among watersheds. Monitoring stations located in rural and agricultural areas showed higher N concentrations during the flood season while those located in areas with urban and industrial centers showed higher N concentration during the dry season. Mainstream flow and N concentrations showed a strong inverse relationship; with higher N concentrations as the river flow declined. Intensive water extraction for agricultural irrigation and increasing N input to the river from fertilized agricultural fields could explain the increasing N concentrations during extensive droughts.

Agriculture↗