Content of brain aluminum is not elevated in Alzheimer disease.

Several studies have reported that the bulk aluminum (Al) concentration is increased in the brain in Alzheimer disease (AD), while other studies have failed to demonstrate an increase. Most of these investigations have had one or more methodological deficiencies, including lack of adequate neuropathological assessment; failure to age-match the control samples; small sample sizes, lacking statistical power; and geographical heterogeneity in the AD and control populations. The present population-based study of 92 clinically and histopathologically diagnosed AD patients and normal elderly nursing home residents was designed to avoid these potential biases. When a subsample of AD cases with the most severe brain pathology was compared with controls having no or minimal pathology, no statistically significant differences were found in the bulk aluminum concentration measured by graphite furnace atomic absorption spectrometry in frontal cortex (1.8 +/- 0.7 vs. 1.7 +/- 0.7 micrograms/g dry wt), temporal cortex (1.4 +/- 0.3 vs. 1.5 +/- 0.5 micrograms/g dry wt), liver (2.0 +/- 1.3 vs. 2.0 +/- 1.2 micrograms/g dry wt), or head of femur (2.4 +/- 1.6 vs. 2.2 +/- 1.0 micrograms/g ash wt). Within the whole series of 92 cases, there was no difference in the bulk aluminum concentration of the frontal cortex between individuals diagnosed as definite, probable, and possible cases of AD using the CERAD (Consortium to Establish a Registry for Alzheimer's Disease) criteria. The density of senile plaques and neurofibrillary tangles in frontal and temporal cortex showed no correlation with the bulk aluminum concentration. Logistic regression analyses, which controlled for age and sex, did not influence outcome for any of the comparisons. The data show conclusively that in AD, bulk aluminum concentration is not increased in two cortical brain regions that are selectively vulnerable to the neuropathological changes associated with this disorder.

A method for checking regression models in survival analysis based on the risk score.

We propose to perform model check for the Cox and Aalen regression models using martingale residual processes grouped after the risk score. Asymptotic distributions of the grouped martingale residual processes are deduced, so both formal and graphical model check can be performed. The method is validated by stochastic simulation. A data example with patients with primary biliary cirrhosis of the liver is discussed.

Changes in periodontal treatment needs. A follow-up study of Oslo citizens from the ages of 35 to 50 years.

A random sample of 35-year-old subjects from Oslo took part in a dental survey in 1973 and were re-examined in 1988. Eighty-one subjects (85%) attended the final examination. The need for periodontal treatment was assessed by the Periodontal Treatment Need System (PTNS), and the oral hygiene by the Simplified Oral Hygiene Index (OHI-S). The participants attended a structured interview and answered a questionnaire about general and dental health habits as well as psycho-social factors. Only small changes in the distribution of subjects in the different PTNS categories were found to have taken place during the 15 years. In 1973, 56.8% were in need of scaling (Class B) and 32.1% had one or more deep inflamed pockets (Class C), and in 1988 the scores were 54.3% and 30.1% respectively. A logistic regression model was used to study the associations between risk factors and increased treatment need, as expressed by increase in the number of C-quadrants. Increased number of C-quadrants was positively associated both with short duration of education and with no interdental cleaning. Using a socio-ecological model for periodontal diseases, variables describing the items "behaviour" and "environment" were found to be most closely associated with increased need for periodontal treatment.

A socio-ecologic model for periodontal diseases.

A socio-ecologic conceptual model for periodontal diseases has been proposed. The model, which includes 4 items: health-care organization, human biology, behavioral factors, and environment, has been tested on a random-sample of 50-year-old Oslo citizens. The investigation is based on a clinical examination as well as a questionnaire and structured interview. A logistic regression model was used to study associations between risk factors and the probability of deep periodontal pockets (> 5.5 mm). The risk of periodontal pockets was positively associated with: short duration of education, being of male gender, previous periodontal treatment, poor oral hygiene and infrequent toothbrushing. Variables describing behavioral factors and human biology were the items found to be most closely associated with periodontal pocketing.

Results of an efficacy trial with an outer membrane vesicle vaccine against systemic serogroup B meningococcal disease in Norway.

A placebo controlled, double blind efficacy trial with a new outer membrane vesicle vaccine against systemic meningococcal disease of serogroup B, has been conducted in Norwegian secondary schools. The study was randomized at school level (1335 schools) and 171,800 students volunteered. The study started in October 1988 and the code was opened in June 1991. Out of the thirty-six proven cases of acute, severe, systemic disease caused by serogroup B meningococci among the participants, twelve occurred in eleven schools given vaccine, twenty-four in twenty-four schools given placebo. twenty-four cases were recorded among secondary school students who did not participate in the study. The protection rate was calculated to 57.4% with a p-value of 1.2% and lower limit of confidence (95%) to 27.7%. The results have initiated research towards an improved outer membrane vesicle vaccine against this disease.

Design of clinical trials with an outer membrane vesicle vaccine against systemic serogroup B meningococcal disease in Norway.

An outer membrane vesicle vaccine against acute, systemic disease caused by meningococci of serogroup B has been developed. The vaccine has been tested consecutively in phase I and phase II clinical trials including more than 5000 volunteers. These trials provided data on safety, immunogenicity and reactogenicity and possible effect on carriage of meningococci in the throat, and consequently formed the basis for two major protection trials; one in secondary school students and one among military recruits. The aims, design and major results of phase I and phase II studies are described as well as the design and organization of the protection trials.

Effect of outer membrane vesicle vaccine against group B meningococcal disease in Norway.

For more than 15 years, Norway has had the highest incidence of meningococcal disease in northern Europe, with 80% of cases being due to serogroup B meningococci. The case-fatality has remained high, at about 10%. In this study, an outer membrane vaccine, which had previously been shown to induce an increase in bactericidal antibodies to the parent strain, was assessed in a large-scale, randomised, double-blind trial. From October, 1988, 171,800 students in secondary schools volunteered to take part in a double-blind, placebo-controlled, efficacy trial with school as the randomisation unit. Hospitals and clinics that routinely receive patients with infectious disease were asked to report urgently all cases of suspected meningitis and/or septicaemia in 13-21-year-old students in Norway. These cases were registered and further investigated according to a detailed protocol. 89 out of the 221 cases investigated by June 3, 1991, were shown to be severe systemic disease due to group B meningococci. 36 cases in 35 schools took part in the trial (11 schools with vaccinated students and 24 with students given placebo). The calculated rate of protection was thus 57.2% (p = 0.012, one-sided test). The findings suggest that, although the vaccine conferred protection against group B meningococcal disease, the effect was insufficient to justify a public vaccination programme.

The potential for spread of HIV in the heterosexual population in Norway: a model study.

A simulation model is used to investigate the potential for indigenous spread of human immunodeficiency virus (HIV) in the heterosexual population in Norway. The heterosexual population is grouped according to age, sex and whether paired or single. Estimates of various parameters of sexual behaviour are taken from a population-based questionnaire study. The questionnaire was sent to a random sample of 10,000 individuals, with a response rate of 63 per cent. The main simulation result is that with no inflow of infection from other risk groups, the heterosexual epidemic will decline if the average transmission probability per intercourse is 1 per cent or less. This result is insensitive to changes in the initial conditions. It is sensitive to changes in sexual behaviour, and to the shape of the transmission probability distribution. A review of empirical partner study data indicates an average transmission probability about 0.1 per cent per intercourse when no transmission modulating cofactors are present. It is concluded that with present sexual behaviour, the indigenous spread of HIV is not likely to sustain an epidemic in the Norwegian heterosexual population.

[Prediction of the extent of heterosexual HIV infections in Norway in the 1990s]. / Spådommer for omfanget av heteroseksuelt betinget HIV-infeksjon i Norge i 1990-årene.

Using a mathematical model, the extent of heterosexual HIV-infection in the years 1987-2000 is assessed on the basis of population-based data on sexual behaviour and data from the surveillance system for HIV-infections. The most probable prognosis give about 200 new cases of heterosexual HIV-infection per year at the end of the period, with a prevalence of HIV-infection of about 1,000 persons in the year 2000. According to the prognosis about 50 new cases of heterosexually acquired AIDS will occur per year in the late 1990s. The discrepancy between a high prognosis and a low prognosis is several hundred cases of HIV-infection per year. More precise prognoses will depend on routine collection of population-based data on risk behaviour and spread of infection.

Respiratory symptoms and lung function of aluminum potroom workers.

The association of occupational exposure with respiratory disease and lung function was examined in a cross-sectional study of 1805 aluminum potroom workers. Work-related asthmatic symptoms occurred in 15% of the workers with an exposure of 10 years or more and in 8% of the workers who had been employed less than five years. In a multiple logistic regression analysis an odds ratio (OR) of 3.4 [95% confidence interval (95% CI) 2.1-5.8] for work-related asthmatic symptoms was estimated for long versus short duration of employment. Airflow limitation was also significantly related to years of exposure (OR 2.6, 95% CI 1.7-3.9). Current occupational exposure and the occurrence of respiratory symptoms were not significantly associated. The results suggest that exposure to air pollutants in the primary aluminum industry may lead to the development of asthmatic symptoms, as well as to reduced respiratory function.

Prediction of sexual behaviour in a group of young Norwegian adults.

The purpose of the present study was to identify predictors of sexual promiscuity and use of condoms. The empirical data stem from a postal survey of a representative sample of persons aged 19-24 in a medium-sized Norwegian town (n = 565). Four selected predictors explained 28.1% and 17.8% of the variance in promiscuity among men and women, respectively. The strongest predictors of sexual promiscuity of men were "la dolce vita" (i.e. alcohol consumption and visits to discoteque/cinema) and marital status. For women the strongest predictors of sexual promiscuity were marital status and age at first intercourse. Knowledge of HIV/AIDS had no significant effect upon either female nor male promiscuity. Six predictors, including promiscuity and knowledge of HIV/AIDS, did not explain a substantial proportion of the variance of condom use neither among men nor women. Age at first intercourse was the only significant predictor upon use of condoms for both men and women.