[Significance of playroom area for morbidity in day care centers in Copenhagen]. / Pladsforholdenes betydning for sygeligheden i københavnske vuggestuer.

Absence due to illness among children in 24 daycare centres in Copenhagen was registered during two periods of one year each with a five year interval. The results from the first period have been reported earlier. In each period, the physical, environmental, hygienic and social conditions of the institutions were assessed, and the playroom area per child was registered. The total number of children increased from 855 in the first period to 921 in the second because 13 of the 24 institutions had increased their capacity in the intervening period. On average, the playroom area per child decreased with 0.27 square metre per child in the 13 institutions with an increased number of children. All children were less than three years of age. Absence due to sickness constituted 7.6% of the days during which the institutions were open. For the second period, where the childrens age had been exactly registered, the effect of age on absence due to sickness was found to be statistically significant. The direction of the effect was a decrease in illness with increasing age. However, due to a high correlation between age and time attending the institution, the effect of age could not be separated from the similar effect of length of time that the child had attended the institution. It was found that sickness will decrease with 7.8% per month that the age of the child and time attending the institution is increased. A statistically significant connection was found between the playroom area per child and absence due to sickness after correction for the influence of age in a multivariate analysis. In conclusion, the sickness will decrease with 10.8% per square metre the playroom area per child is increased.

Respiratory illnesses in children and air pollution in Copenhagen.

The relationship between air pollution and the daily number of contacts (i.e., telephone calls and home visits) with or at Copenhagen Emergency Medical Service for children with and without respiratory illnesses was studied during a 91-d period (i.e., January 14, 1991, to April 14, 1991). A total of 12,132 contacts occurred. Diagnoses, which were recorded on the invoices for 5,307 contacts, revealed that 3,974 contacts were the result of respiratory illnesses. Regression analysis was used to investigate the short-term relationship between pollutants (i.e., carbon monoxide, nitric oxide, nitrogen dioxide, NOx, sulfur dioxide, ozone, and black smoke), measured at monitoring stations, and both the number of all contacts for children and the number of contacts for children with respiratory illnesses. Temperature and systematic effects that were the result of holidays and weekends were controlled for, after which only nitric oxide and NOx were associated significantly with the number of contacts for children who had respiratory illnesses. Nitric oxide and NOx, as indicators of traffic pollution, appeared, at low levels, to slightly exacerbate respiratory illnesses among children.

[Morbidity of children attending day care centers in Copenhagen illustrated by social, physical, environmental and hygienic factors]. / Sygeligheden i københavnske vuggestuer belyst ud fra sociale, fysiske, miljømaessige og hygiejniske faktorer.

Sick leave among the children in 24 day nurseries in Copenhagen was registered during a period of one year. The physical, environmental and hygienic conditions of the institutions were assessed by means of interviews and inspection, supplemented by information from the local authorities. Sick leave constitutes 7.5% of the days during which the institutions were open and the average number of sick days per child varied from 14.6 to 24.4. Comparisons with similar investigations are inclusive on account of variations in the methods of registration and age distributions. It was characteristic of the institutions investigated that these included a number of old institutions in flats, many in streets with considerable traffic and where the conditions of ventilation and space do not conform with present-day standards. In some of the institutions, the hygiene is unsatisfactory, particularly where ventilation, outdoor activities and hand-washing are concerned. A statistically significant connection was found between amount of traffic at the institution, the hygiene and playroom area per child, on one hand, and absence due to sickness, on the other, as assessed by a statistical model for sick leave for child in a given institution. In order to prevent sickness, it is concluded that efforts to improve hygiene and space are desirable and, similarly, further research concerning the effects of atmospheric pollution is relevant.

Analysis of the incubation period for measles in the epidemic in Greenland in 1951 using a variance components model.

This paper presents a model for analysing the incubation period of highly infectious diseases in populations where almost all susceptibles become infected during an epidemic. The model leads to a simple method for estimating the variance of the duration of the incubation period without any distributional assumptions. Further, the influence of covariates on the duration of the incubation period can be analysed. Data from the epidemic of measles in Greenland in 1951 are analysed and it is found that intersymptom times are correlated within households, suggesting that secondary cases are infected almost simultaneously. This result is inconsistent with a variation in the times of infection of secondary cases within a household which is often assumed when analysing data on measles. Prophylactic treatment did not prevent infection in the epidemic in Greenland, but it is found that the incubation period tended to be shorter for persons not receiving prophylactic treatment.

Prepro-vasoactive intestinal polypeptide-derived peptide sequences in cerebral blood vessels of rats: on the functional anatomy of metabolic autoregulation.

This study describes the distribution of peptide sequences derived from the prepro-vasoactive intestinal polypeptide (preproVIP) molecule in perivascular nerves of rat brain arteries and arterioles. The peptides were identified by immunohistochemistry using highly specific antibodies. Five peptide sequences (preproVIP 60-76, peptide histidine isoleucine (PHI), preproVIP 111-122, VIP, and preproVIP 156-170) were identified in the perivascular nerves throughout the arterial cerebral circulation. The density of the immunoreactive fibers was highest in the nerves of the larger extracerebral arteries, declining in smaller branching arteries. All peptide sequences were identified in the nerves of small pial arterioles overlying the cortical convexity, whereas capillaries and veins contained no immunoreactive material. Dendritic processes of neocortical neurons immunoreactive for VIP and PHI could be followed towards the brain surface where the processes penetrated into the pial layer, often close to the pial vasculature. Some of the processes were also observed to enter the Virchow-Robin space, close to the arterioles. It is possible that cortical nerve cells containing VIP and PHI release the peptides in the perivascular space during periods of activity and thereby contribute to local vasodilatation associated with changes of neuronal function.

Delayed excess mortality after exposure to measles during the first six months of life.

In an urban area of Guinea-Bissau, 71 children exposed to measles before age 6 months had a mortality risk of 34% (95% confidence interval (Cl) 24-47) between 6 and 60 months of age. The mortality risk for the 205 other children of the same birth cohort who had not been exposed to or developed measles was 11% (95% Cl 9-15), a significant difference compared with exposed children. With a version of the Cox regression model, maternal education was found to be the only background factor with a significant effect on mortality. When background factors were controlled for, the mortality of children exposed to measles was significantly higher than that of controls in each of the age intervals 6-11, 12-23, and 24-35 months. For the large subgroup of children of mothers without any formal education, exposed children had 5.7 times (95% Cl 2.7-12.0) higher mortality than did the control children in the age interval 6-35 months. Diarrhea deaths were particularly common among exposed children. Of 22 children who had been exposed before age 6 months during a subsequent epidemic and had a blood test taken, there was a significantly higher mortality risk (27%) between 6 months and 5 years than in the 26 controls who had a blood test (0%). Children who had elevated antibody titers to measles after exposure had a particularly high mortality compared with controls. These results suggest that later childhood mortality may be related to infectious experiences during the first months of life. The possible long-term health consequences of exposure to measles virus should be considered when assessing the value of measles control programs.

Piecewise comparison of survival functions in stratified proportional hazards models.

A numerical test of identity of hazards in Cox's regression model in the case when the observations have been stratified according to some covariate (possibly time-dependent) and the regression coefficient is common to all strata is proposed. The test is applied to analysis of the effect of early exposure to measles.

Histomorphometrical analysis of the influence of soft diet on masticatory muscle development in the muscular dystrophic mouse.

The known difference in the severity of dystrophy between the masseter and the digastric muscle of the mouse (dy/dy C57BL/J6) may be attributed to the differences in muscle work load. This possibility was tested by subjecting 3-week-old mice (normal and dystrophic) to a soft diet for 4 weeks. Microscopic examination of haematoxylin-eosin stained sections of these muscles showed that the fibre size dispersion (a measure of disease severity) decreased slightly but significantly in the masseters of mice on a soft diet. It was thus possible to improve the condition of dystrophic masticatory muscles by changing their function. Body weight curves measured during the experimental period suggest that the dystrophic mice may have been under weight because of malnutrition due to lack of sufficient masticatory power.

Cortical spreading depression is associated with arachidonic acid accumulation and preservation of energy charge.

The present study aimed to study the relation between the release of arachidonic acid (AA) and the energy state in cerebral cortices of rats during single episodes of cortical spreading depression (CSD). The changes in concentrations of AA, labile phosphate compounds [ATP, ADP, AMP, and phosphocreatine (PCr)], and glycolytic metabolites (lactate, pyruvate, glucose, and glycogen) were studied during and following the large change of the local direct current (DC) potential. Free AA increased markedly during the DC shift, continued to increase during the subsequent 3 min, and returned to control levels at 4-5 min after CSD. PCr decreased by 38% in the first minutes following the DC shift, while ADP increased by 38%. Both returned to normal within a few minutes. ATP, AMP, and energy charge remained constant throughout the experimental period. Glucose decreased by 47% and glycogen by 34% for a few minutes following CSD, while lactate increased by 105% at 2-3 min and by 77% at 4-5 min after CSD. The metabolites returned to control levels at 10 min after CSD. Considering the constant energy charge at all time points during CSD, it is suggested that the AA rise reflects augmented phospholipase activity due to either increased intracellular [Ca2+] or receptor stimulation or both. The possibility that N-methyl-D-aspartate receptors play a role in the release of AA, and that free AA in turn could be part of the mechanism of CSD, is discussed.

Chemotaxis in tetrahymena.

Chemotaxis - that is oriented locomotion of single cells - was shown by motion analysis of Tetrahymena thermophila. An electronic registration of swimming tracks was carried out in gradients of chemoattractant established in a modified Zigmond chamber. The attractants used were proteose peptone, platelet extract and fibroblast growth factor. From 5 to 55 minutes after addition of the chemoattractant, 65% of the cells are oriented within the 180° angle segment towards the attractant compared to 51% in the control, containing no attractant. The figures are based on the measurement of 1567 and 499 tracks, respectively. Under the conditions used, cell migration towards the attractant is caused, solely, by an oriented movement (Chemotaxis) since the swimming speed was unaffected by the presence of the attractant. Similar results were obtained using T. pyriformis cells.

Shifts between use and non-use of dental services among young Danish adults over a 3-year period.

Utilization of dental services among three groups of young adults was studied longitudinally. Each year from age 16 to age 19, participants were defined as users or non-users of alternative dental programs. Dental programs were taking place with public dental health service clinics (n = 386), with private dental practitioners, free of charge (n = 161), and with private dental practitioners, partially reimbursed by health insurance (n = 261). The paper analyzes whether the pattern of utilization of the last two groups might be described by a Markovian model defining use or non-use of dental care each of 3 years as two mutually exclusive Markovian states. Contingency table analysis of the relationships of the utilization status and sex, social group, and delivery program showed that the utilization pattern could not be described by a Markovian model. Conversely, strong relationships between 1-yr user status and 3-yr user status was found. Implications in relation to the prevailing dental health care policy emphasizing regular dental care and continuity between child dental health care and young adult dental programs are discussed.

Utilization of alternative delivery programs in youth dental care in Denmark.

Three groups of young adults were offered three different dental programs from ages 16 to 19: one group of 386 persons continued preventive and curative dental care in the Public Child Dental Health Service (Public group), one group of 161 persons was offered dental care with private dental practitioners of own choice with care paid by the municipality and the health insurance (Mixed group), and one group of 261 persons entered the general young adult dental program under the National Health Insurance with free choice of private dental practitioner with reimbursement of about 75% from the insurance (Private group). Almost 100% of the Public group used the dental services continuously. Less than half of the Mixed group and about two thirds of the Private group went regularly to a dentist, women more than men. Discrepancies were found between the expected utilization and actual utilization, and a tendency was noted to overrate self-reported utilization in relation to actual utilization. It is concluded that continuity of dental care and unambiguous organizational affiliation is a prerequisite for a high utilization rate, but it also seems that the outreaching work done by the child dental health service is effective with regard to utilization.

The distribution of stature among Danish conscripts in 1852-56.

Stature measurements on large samples of unselected 22-year-old Danish males from the period 1852-56 are analysed. Data are given for 18 rural counties and the City of Copenhagen. The distribution of stature deviates significantly and systematically from Normality in all counties. A mixture of two Normal distributions with equal variances describes the empirical distribution of stature in the 18 rural counties and explains important aspects of the distribution of stature in the City of Copenhagen. This mixed structure of the population is accomplished by a factor reducing the mean stature of a fraction of the population by nearly 20 cm. The factor generating this mixed population is probably genetic and inbreeding may play a major part in raising the frequency of affected persons to the observed values, 0.2-2%. The mean stature of the majority of the population and the mixing proportion show significant geographical variation. The frequency of the small subpopulation is generally highest in the least-developed main province, Jutland, and lower on the islands, particularly in and around the City of Copenhagen. On the Zealand group of islands the mean stature of the majority of the population is highest in the most developed area, whereas the reverse occurs in Jutland.