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T Tosteson

Publications and source records attributed to T Tosteson.

14 recordsLinked to original sources
PubMed2001

Expiratory and inspiratory forced vital capacity and one-second forced volume in asymptomatic never-smokers in Norway.

The objectives of this study were to examine within and between individual variation detected during forced expiratory (FE) and forced inspiratory (FI) manoeuvers in a general population and to investigate the dependence of these variables on age, body size, and gender. A random sample of asymptomatic never smokers who had never been exposed occupationally to quartz or asbestos and who were living on the south-western coast of Norway were examined by spirometry; 81% of the individuals invited to attend did so. Of the 488 subjects between 18 and 73 years of age, 98% contributed three acceptable recordings for forced expiratory vital capacity (FVC) and one-second forced expiratory volume (FEV1), 94% contributed three acceptable recordings for forced inspiratory vital capacity (FIVC) and 85% contributed three acceptable recordings for one-second forced inspiratory volume (FIV(1)). The within-subject variation increased with body height and was considerably larger for FIV(1) than for FVC, FEV(1) or FIVC. A four-parameter model of pulmonary function measurement divided by height squared, including a gender term and a linear and quadratic term of age, fit the median of the observed values well. The residuals had a close-to-normal distribution, and the fifth-percentile values were estimated as the lower limit of normal. The peak value of dynamic lung volumes was observed into the middle of the fourth decade of life, and the decline thereafter did not differ greatly between the genders or among the different indices. The forced inspiratory volumes are the first reported in any reference population.

Adolescent↗
PubMed1999

Heavy metals, lipid peroxidation, and ciguatera toxicity in the liver of the Caribbean barracuda (Sphyraena barracuda).

Human consumption of over 400 species of tropical fish containing polyether toxins (e.g. ciguatoxins, maitotoxins) causes ciguatera fish poisoning. The Caribbean barracuda (Sphyraena barracuda) is one of the most potent ciguatoxic fish. The objective of this study was to determine whether toxicity of 14 barracuda livers was correlated with lipid peroxidation. A significant correlation (p = 0.015, Pearson's correlation) between lipid peroxidation and toxicity of barracuda liver was found. Because iron and copper are well-known catalysts of hydroxyl radical production and lipid peroxidation in biological systems, the correlation between the concentrations of these metals in barracuda liver and lipid peroxidation and toxicity was also investigated. Cadmium was significantly correlated (p = 0.014) with the toxicity of barracuda livers. This study provides the first data concerning the concentration of iron, copper, and cadmium in the liver of the Caribbean barracuda. Of the three metals studied in barracuda liver, iron was the most abundant, followed by copper and cadmium. Lipid peroxidation was highly variable and detected in five (36%) of the liver samples. Lipid peroxidation was not statistically significantly correlated (p > 0.05) with concentrations of iron, copper, and cadmium in barracuda liver. Collectively, these findings provide additional evidence that lipid peroxidation can be a mechanistic component of ciguatera toxicity in the Caribbean barracuda.

Animals↗
PubMed1995

Dacarbazine, cisplatin and carmustine, with or without tamoxifen, for metastatic melanoma: 5-year follow-up.

Metastatic melanoma has a grim prognosis. Response rates and survival of patients treated with combination chemotherapy are not superior to single-agent chemotherapy. This study seeks to evaluate the objective response rate and survival of patients with metastatic melanoma treated with multiagent chemotherapy, with or without tamoxifen. Forty-two patients with metastatic melanoma were treated from March 1982 to February 1988 with dacarbazine, cisplatin and carmustine, with or without tamoxifen. An overall objective response rate of 43% was seen (complete response rate 17%; partial response rate, 26%). The response rate was 54% for patients treated with tamoxifen and 25% for patients treated without tamoxifen, but the results did not achieve statistical significance. Median overall survival was 412 days, and was significantly longer in the tamoxifen-treated group. Combination chemotherapy as described in this study is well-tolerated. The observation that tamoxifen appears to impact on survival should be interpreted with great caution due to the deficiencies in the design of the trial and small patient numbers. A randomized trial of this regimen vs single-agent chemotherapy is indicated and is currently being conducted.

Adult↗
PubMed1994

Racial differences in fracture risk.

Blacks appear to have a lower risk of fractures than whites, but there has been little research regarding racial differences in the risk of fractures at sites other than the hip. We used Medicare claims to investigate the risks of fractures of the hip, distal forearm, proximal humerus, and ankle among American whites and blacks over 65 years old. Each of these fractures occurred more frequently in women than in men and (except for ankle fracture) displayed an increase in risk with age. Blacks had a lower risk than whites, although these differences were smaller for fractures of the ankle and were less pronounced among men. The most likely explanation for this is a constitutional or metabolic factor prevalent in blacks that particularly influences the risk of osteoporotic fractures in women.

Aged↗
PubMed1993

Association of immune activation with intravenous heroin use and methadone treatment in HIV-1 seropositive and seronegative subjects.

This study evaluated the effect of continued heroin use during methadone treatment on serum neopterin levels in 40 human immunodeficiency virus (HIV) type 1 seropositive (HIV+) and 70 seronegative (HIV-) intravenous drug users (IVDUs). Persistent drug use, determined by urinary evidence of opiates, was more common in HIV+ than in HIV- IVDUs (p = 0.01). Serum neopterin concentration, an indicator of increased probability of progression to AIDS, was elevated in HIV+ IVDUs, p < 0.0001 (mean 16.0 nmol/L) compared to that of HIV- IVDUs (mean 10.0 nmol/L) and in persistent IV drug users compared with abstainers, p < 0.0001. The effect of drug use and HIV status on serum neopterin was not explained by differences in methadone treatment, age, sex, or total years of i.v. drug use. Neopterin decreased in 25 IVDUs, regardless of HIV serostatus, treated with methadone for an average of 1.5 years.

Adult↗
PubMed1992

Single breath transfer factor for carbon monoxide in an asymptomatic population of never smokers.

BACKGROUND: Data on reference values of transfer factor variables in general populations of asymptomatic never smokers are limited. The aim of this study was to examine the relation between test variables and age, height, haemoglobin concentration and carboxyhaemoglobin concentration. METHODS: Measurements of single breath transfer factor for carbon monoxide (TLCO) were obtained for a randomly selected sample of never smokers in north western Europe who were 18-73 years old and had no respiratory symptoms or disorders. Two recordings of TLCO with a ratio of inspiratory vital capacity to forced vital capacity of greater than 0.09 were obtained by standardised techniques for 304 subjects. RESULTS: The measurement errors expressed as a percentage of the common mean value of TLCO, volume adjusted TLCO (KCO), and alveolar volume (VA) were 4.5%, 4.2%, and 2.4% respectively. Multiple linear regressions showed sex specific effects of height and age on TLCO, and, in addition, of haemoglobin and carboxyhaemoglobin concentrations on KCO. VA was associated with height but not with age. The 5th and 95th centiles for TLCO and KCO in men and women were between 78% and 82% and between 120% and 127%, respectively, of predicted values when age and height were taken into account. CONCLUSION: Reference equations and normal values for transfer test variables in a large healthy population of never smokers are described in relation to age, height, and haemoglobin concentrations. To our knowledge, this is the first report of an association between carboxyhaemoglobin concentrations and KCO in a population of never smoking men and women.

Adolescent↗
PubMed1992

Effects of ambient ozone on respiratory function and symptoms in Mexico City schoolchildren.

The effects of ambient ozone (O3) on respiratory function and acute respiratory symptoms were evaluated in 143 7- to 9-yr-old schoolchildren followed longitudinally at 1- to 2-wk intervals over a period of 6 months at three schools in Pedregal, Mexico City. The maximum O3 level exceeded the World Health Organization guideline of 80 ppb and the U.S. standard of 120 ppb in every week. For an increase from lowest to highest in the mean O3 level during the 48 hr before spirometry (53 ppb), logistic regression estimated relative odds of 1.7 for a child reporting cough/phlegm on the day of spirometry. For the full population, the mean O3 level during the hour before spirometry, not adjusted for temperature and humidity, predicted a significant decrement in FVC but not in FEV1 or FEF25-75. In contrast, the mean O3 level during the previous 24-, 48-, and 168-h periods predicted significant decrements in FEV1 and FEF25-75 but not in FVC. Ozone was consistently associated with a greater decrement in lung function for the 15 children with chronic phlegm as compared with the children without chronic cough, chronic phlegm, or wheeze. Ozone in the previous 24-, 48-, and 168-h periods predicted decrements in FEV1 for children of mothers who were current or former smokers, but not for children of mothers who were never smokers. Many of these effects were reduced in multiple regression analyses including temperature and humidity, as temperature and O3 were highly correlated.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants↗
PubMed1992

Studies in the genetics of obstructive sleep apnea. Familial aggregation of symptoms associated with sleep-related breathing disturbances.

Previous studies of single families have suggested that familial factors may be important in the pathogenesis of obstructive sleep apnea. In this report, the role of inheritance in obstructive sleep apnea was assessed by quantitating the degree of familial clustering of symptoms associated with sleep-related breathing disorders. In total, 272 subjects from 29 families identified through an index case with obstructive sleep apnea and 21 control families with no relative known to have sleep apnea were studied with questionnaires that ascertained health status and symptoms. The unadjusted odds ratios of habitual or disruptive snoring, breathing pauses, and excessive day-time sleepiness in subjects with a single relative with the same symptom were 1.40 to 1.53 (p less than 0.05). Odds ratios increased progressively for subjects with increasing numbers of symptomatic relatives). Adjustment for body mass index, age, and gender modestly reduced these odds ratios to 1.33 to 1.42. These data suggest a significant familial aggregation of symptoms associated with sleep-disordered breathing that appears independent of familial similarities in weight.

Adult↗
PubMed1991

Protection against endocarditis due to Staphylococcus epidermidis by immunization with capsular polysaccharide/adhesin.

BACKGROUND: Staphylococcus epidermidis is the principal pathogen in prosthetic valve endocarditis. The capsular polysaccharide adhesin (PS/A) has been shown to mediate attachment of bacteria to medical devices. In this study, we investigated the efficacy of active and passive immunization against PS/A in preventing S. epidermidis endocarditis in a rabbit model. METHODS AND RESULTS: Aortic valve vegetations were produced by inserting a Teflon catheter into the left ventricle through the right carotid artery. Bacteremia and endocarditis were then established by implanting in the left jugular vein a catheter that was attached to an osmotic pump and contaminated with S. epidermidis strain RP62A. During a 3-week study period, of 64 blood cultures taken every second or third day from six nonimmune rabbits, 54 (84%) yielded strain RP62A. In rabbits actively immunized with PS/A, eight of 60 blood cultures (13%) were positive (odds ratio 5.0, 95% CI, 2.0-12.3, p = 0.005). At death, all six nonimmune rabbits had infected vegetations that yielded 10(6)-10(11) colony-forming units (cfu)/g of vegetation, whereas only one PS/A-immunized rabbit had an infected vegetation. Immunization protocols designed to elicit antibody to teichoic acid but not to PS/A afforded no protection against bacteremia or endocarditis. Infusion of monoclonal antibody to PS/A through a catheter in the right jugular vein provided a level of protection against both bacteremia and endocarditis comparable to that produced by active immunization. In vitro, antibody against PS/A was opsonic for S. epidermidis. CONCLUSIONS: Immunoprophylaxis targeted at staphylococcal PS/A is a promising new approach to the prevention of prosthetic valve endocarditis.

Animals↗
PubMed1991

Measurement of sleep-related breathing disturbances in epidemiologic studies. Assessment of the validity and reproducibility of a portable monitoring device.

The feasibility and reliability of measuring sleep-related breathing disorders with a portable monitor (PM) were assessed in a heterogeneous population, consisting of 31 patients recruited from a sleep laboratory and pulmonary disease clinic, 16 participants in a genetic-epidemiologic study of sleep apnea, and four volunteers with no specific sleep complaints. The validity of measurements made by the PM was assessed with comparisons of respiratory parameters made with the PM to those determined with in-hospital polysomnography (PSG) (25 studies). Reproducibility was assessed in 29 subjects who underwent in-home monitoring on two occasions. There was a high level of agreement between the number of respiratory events (apneas or hypopneas) per hour of estimated sleep (respiratory disturbance index, RDI) recorded with the PM and PSG and log-transformed (r = 0.96). Using a RDI of greater than or equal to 10 to define "abnormality," 20 of the 21 subjects who would have been classified as abnormal with PSG were classified similarly with use of the PM. A similar high level of agreement was demonstrated for the log-transformed RDI determined with replicate in-home studies (r = 0.94). No evidence of a "first-night effect" for the RDI was suggested in studies performed with the PM; ie, RDI was 18.4 +/- 27.7 and 17.4 +/- 25.7 (mean +/- SD) for first and second night studies, respectively (p = 0.21). A second compared with an initial study with the PM would have resulted in reclassification of abnormality based on an RDI of greater than or equal to 10 in one subject. These findings suggest that measurement of the RDI with in-home monitoring provides a valid and highly reproducible index for assessment of sleep-related respiratory disturbances for use in epidemiologic studies of general populations.

Adult↗
PubMed1990

Screening for subclinical sleep-disordered breathing.

We evaluated self-administered questionnaires and short sleep studies in screening for sleep-disordered breathing (SDB) in 40 hypertensive men ages 36-66 unselected for symptoms. Each subject completed a questionnaire including questions on sleep-related symptoms and underwent overnight polysomnography in which we evaluated the apnea-hypopnea index (AHI) and the percentage of time during which arterial O2 saturation was less than 90% (T90). The first 90 min of overnight study was evaluated separately, and 10 subjects with an AHI greater than or equal to 10 also underwent late afternoon nap study. By overnight polysomnography, 48% of the cohort had an AHI greater than or equal to 10, and 35% had a T90 greater than or equal to 10%. Using linear regression, we found no features of the symptom questionnaire that strongly predicted AHI. Only self-reported snoring and baseline arterial Po2 significantly predicted T90. The AHI and T90 were not significantly correlated. Considering an AHI greater than or equal to 10 in the overnight study as "abnormal" and an AHI greater than or equal to 10 on the short study as a "positive" test, the specificity of the AHI in the first 90 min was 100% (21/21), and the sensitivity was 42% (8/19). The sensitivity of the nap study was 60% (6/10). We conclude that in a cohort unselected for symptoms, the ability of self-administered questionnaires to predict SDB was low; short studies were only moderately sensitive for detecting an AHI greater than or equal to 10, and the AHI was not a major determinant of nocturnal desaturation.

Adult↗
PubMedDate not supplied

Familial aggregation studies with matched proband sampling.

A method is proposed for the analysis of clustered, continuous data arising from matched familial aggregation studies. The problem is suggested by a study designed to estimate the familial aggregation of obstructive sleep apnea (OSA). The study design uses 'proband' sampling, in which individuals identified at sleep clinics as having a high degree of OSA ('cases') are matched to neighborhood 'controls', individuals with normal levels of OSA. The resulting data are used to develop estimates of familial correlations for indices of hypopnea/apnea derived from the sleep monitoring of individual family members. The properties of conditional multivariate normal distributions and random-effects models are used to accommodate proband sampling and matching effects. Examples and simulations are used to demonstrate the importance of applying the proposed procedures.

Adolescent↗