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Biomedical subjects

H Christensen

Publications and source records attributed to H Christensen.

At least 289 records · Page 16Linked to original sources
PubMed1972

A mathematical method for analysing questionnaires.

Investigators using questionnaires are usually confronted with an enormous number of different responses whose significance with respect to a particular characteristic is not immediately clear. This paper presents a simple computational technique for determining the relative merits of each question and a score for each respondent. The rationalization for and the formalization of the method are discussed and some practical examples illustrate how it can be used. The strengths and weaknesses of the method are discussed in relation to those of other methods.

Mathematics↗
PubMed1971

The serological assessment of a tetanus toxoid field trial.

To determine the effectiveness of a method for controlling tetanus neonatorum, a double-blind controlled trial involving 1 618 women was conducted between 1961 and 1966. Women in the study were given 1-3 injections (1 ml) of aluminium-phosphate-adsorbed tetanus toxoid or a placebo (influenza vaccine). At the conclusion of the trial, 5-ml samples of blood were obtained from 299 women. Sera were titrated for anti-tetanus antibodies by two methods.A comparison of the clinical and laboratory results showed a close relationship. It is suggested that the level of protection may be lower than is at present accepted. Antitoxin levels were inversely related to age and directly to the interval between injections. Two widely spaced injections (8 months or more) may be about as effective as 3 injections. One injection of specially prepared toxoid with a high immunizing potency might give significant protection.

Adult↗
PubMed1966

Effect of simultaneous BCG and smallpox vaccination in schoolchildren. Report of a WHO-sponsored preliminary study.

The effect of simultaneous BCG and smallpox vaccination and the possible interaction of primary BCG vaccination and smallpox revaccination were studied in 1099 Burmese children arbitrarily allocated to four groups. All were tuberculin-tested and all had received primary smallpox vaccination but had not been vaccinated with BCG. In the first group, no vaccination was performed; in the second, negative reactors received BCG vaccine; the third received smallpox vaccine; and the fourth also received smallpox vaccine, negative reactors also receiving BCG vaccine.Comparison of the "take" of smallpox revaccinations in the third and fourth groups and the post-vaccination tuberculin allergy in the second and fourth groups gave no suggestion of interaction.There was no difference in the take of smallpox revaccination between tuberculin-negative and tuberculin-positive children, nor did smallpox vaccination influence naturally acquired tuberculin allergy.Smallpox revaccination had no apparent effect on the frequency distribution of BCG vaccination lesions, and further smallpox revaccination after one year showed that BCG vaccination had not influenced smallpox immunity.

Adolescent↗
PubMedDate not supplied

Sequence variation of the 16S to 23S rRNA spacer region in Salmonella enterica.

The possibility for identification of Salmonella enterica serotypes by sequence analysis of the 16S to 23S rRNA internal transcribed spacer was investigated by direct sequencing of polymerase chain reaction-amplified DNA from all operons simultaneously in a collection of 25 strains of 18 different serotypes of S. enterica, and by sequencing individual cloned operons from a single strain. It was only possible to determine the first 117 bases upstream from the 23S rRNA gene by direct sequencing because of variation between the rrn operons. Comparison of sequences from this region allowed separation of only 15 out of the 18 serotypes investigated and was not specific even at the subspecies level of S. enterica. To determine the differences between internal transcribed spacers in more detail, the individual rrn operons of strain JEO 197, serotype IV 43:z4,z23:-, were cloned and sequenced. The strain contained four short internal transcribed spacer fragments of 382-384 bases in length, which were 98.4-99.7% similar to each other and three long fragments of 505 bases with 98.0-99.8% similarity. The study demonstrated a higher degree of interbacterial variation than intrabacterial variation between operons for serotypes of S. enterica.

Base Sequence↗
PubMedDate not supplied

Education, activity, health, blood pressure and apolipoprotein E as predictors of cognitive change in old age: a review.

BACKGROUND: Cross-sectional studies have identified a number of health and lifestyle factors that correlate with cognitive function in old age. It is important to know whether these factors also predict change in cognitive function over time. OBJECTIVE: To evaluate published findings on genetic, health and lifestyle predictors of cognitive change in late adulthood. METHODS: Studies reporting data on education, health, blood pressure, activity and apolipoprotein E (APOE) as predictors of cognitive change were reviewed. A total of 34 studies were identified that reported data on these predictors. The average follow-up period of studies reviewed was 7.68 years. RESULTS: Results showed that education, hypertension, objective indices of health and cardiovascular disease, and APOE were associated with cognitive change. Results regarding the effect of physical activity on cognitive change were inconclusive. CONCLUSION: Despite the lack of data on some predictors, the longitudinal trends are generally consistent with cross-sectional findings on predictors of cognitive performance in old age. More research is required to compare the influence of predictors on different types of cognitive abilities.

Aged↗
PubMedDate not supplied

Are changes in sensory disability, reaction time, and grip strength associated with changes in memory and crystallized Intelligence? A longitudinal analysis in an elderly community sample.

BACKGROUND: Little is known about predictors of cognitive changes in the elderly. Sensory disability, grip strength, and speed of processing have been established as associates of cognitive performance in cross-sectional studies. However, it is not known whether changes in these predictor variables are associated with changes in cognitive functioning. OBJECTIVES: (1) to examine the relationship between initial level of three predictor variables - speed of processing, sensory disability, and grip strength - and changes in memory and crystallized intelligence (CIQ); (2) to examine the relationships between change in grip strength, cognitive speed, and sensory disability and changes in memory and CIQ, and (3) to investigate these relationships with the effects of age and sex statistically removed. METHODS: Cognitive ability was assessed in two domains: CIQ (3 tests) and memory (3 tests) measured on two occasions approximately three and a half years apart in a large community sample (n = 425; mean age = 75.8, range 70-93 years). Repeated-measures Anova was used to analyze descriptive data. Latent-change models were used to examine structural relationships between constructs. RESULTS: Initial levels of reaction time or grip strength did not predict rate of change on memory tasks. Changes in grip strength, speed, and memory correlated moderately, suggesting that these variables have some tendency to move together over time. Sensory disability correlated with age but not with change in speed, grip, memory, or CIQ. These relationships held across the age range studied after adjustment for age and sex. CONCLUSIONS: The findings are consistent with the action of a common causal mechanism underlying changes in speed, grip, and memory. A number of methodological caveats arise from our analysis. Cross-sectional and longitudinal data sets yield different interpretations about the basic component associates of cognitive performance.

Aged↗
PubMedDate not supplied

Cohort difference in sexual orientation: results from a large age-stratified population sample.

BACKGROUND: There is some community survey evidence for a cohort difference in female sexual orientation. OBJECTIVE: To determine whether there is a cohort difference in sexual orientation in Australia. METHODS: A community survey was carried out with a sample of 7,447 adults from the age groups 20-24, 40-44 and 60-64 years. As part of this survey respondents were asked a question on sexual orientation which was answered privately. RESULTS: A strong age cohort difference was found for women, with younger women more frequently reporting a homosexual or bisexual orientation. By contrast, no age cohort difference was found for men. CONCLUSION: These findings suggest that a heterosexual orientation may have become less common in younger cohorts of Australian women. This finding is consistent with data from other recent studies.

Adult↗