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At least 19 recordsLinked to original sources
PubMed1990

Mortality in fishermen: an unusual age distribution.

Age specific standardised mortality ratios (ASMRs) were compared for commercial fishermen under 55 years old and those who were aged 55 and older in the Canadian Atlantic coastal provinces of Nova Scotia, New Brunswick, and Prince Edward Island. The subjects were a cohort of 31,415 fishermen licensed by the Department of Fisheries and Oceans during 1975-83. Mortality was obtained by a computerised linking of the registry of licensed commercial fisheries and the Canadian Mortality Data Base. Fishermen under 55 had ASMRs between 1.4 and 1.7 for death from all causes and around 1.0 for death from non-accidental causes. The older fishermen had ASMRs as low as 0.6 for all causes and non-accidental causes. The same pattern was shown for death from specific causes such as ischaemic heart disease, accidents, and cancer, as well as for different years of entry into the cohort. This pattern differed widely from that of most other occupations. Dividing the cohort into owners and crew members showed that the high mortality ratios at younger ages existed in crew members only. It was concluded that the high death rates for fishermen under 55 had a socioeconomic component.

Accidents, Occupational↗
PubMed1985

Pubic symphysis age distributions.

A further discussion of age assessment and palaeodemography requires detailed reviews of methods, especially pubic symphysis techniques. Before reanalysis of changes in symphyseal form, the initial steps in distributing ages must be examined. Use of the mean values for age scores gives age distributions that are not real, but subject to systematic distortions, and cumulative percentages of skeletal samples can be shown to reflect the mean ages. Distributing skeletal ages using 95% probability distributions provides a more accurate estimation of true ages for palaeodemography and a better basis for discussions of pubic symphysis aging techniques.

Adolescent↗
PubMed1986

Examination of the generalized age distribution.

The formula for the age distribution and other relationships that follow from it for any (non-stable) population presented by Preston and Coale are significant contributions to demography. The formulas summarize the relationships among various demographic measures precisely, and are formally analogous to the relationships that hold for stable populations. The significance of these formulas cannot be overstated; they allow us to understand clearly the relationships among demographic measures in any arbitrary population. However, when it comes to using them for estimating demographic measures when census data are defective, the method of estimation is still affected by defective data. The reason is that the series of age-specific growth rates reflects the observed census age distributions exactly so that any defects in the census data are summarized in the growth rates. This paper begins with the formulation of the discrete version of the "new synthesis" developed by Preston and Coale. With the discrete formulation, the three kinds of errors introduced when the continuous time formulas are applied to real data can be avoided. Then it is pointed out that when two accurate census data are available, the Preston-Coale procedure of "estimating" the age distribution at the second census is equivalent to checking the identity of the age distribution formula. Also "estimating" mortality by the procedure of Preston-Coale is shown to be equivalent to obtaining mortality directly from intercensal survival rates. That the procedure which involves the age-specific growth rates is equivalent to those that involve the intercensal survival rates may have escaped notice because there are no a priori constraints for patterns of age-specific growth rates to follow. The irregularity in growth rates due to defective data are not distinguishable from true irregularity that exists in the population, contrary to the well-known regularity in the pattern of survival rates in human populations.

Actuarial Analysis↗
PubMed1988

Age distribution of progressive multifocal leukoencephalopathy.

The age distribution is given of 79 cases of progressive multifocal leukoencephalopathy confirmed as JC virus infection. The data are compared with a published age distribution of multiple sclerosis onset in Vestfold County, Norway, and with published data from Rochester, Minnesota of the age distribution of viral encephalitis. In contrast to viral encephalitis, 61% of which occurs in children under the age of 10, PML has been identified only once in this age group. PML, like MS, is a disease of adult onset, peaking in the sixth decade of life. The reason for this late onset of a CNS disease caused by a ubiquitous childhood infection is still uncertain, but it may be related to maturation of susceptible cells in the brain, as well as to declining immunity associated with chronic disease and age.

Adolescent↗
PubMed1990

Markov chains as a shortcut method to estimate age distributions in herds of beef cattle under different culling strategies.

Markov chains were used to estimate the age distribution at equilibrium and average age in herds of beef cattle and the age distribution and average age of culled cows. These estimates are essential in systems simulation and economic analyses of beef production alternatives because the biological input and output from a beef production system depend on the age structure of the cows in the system. Ten sets of data on age-specific probabilities of culling for different reasons were found in the literature and used in simulation of different culling strategies. Three different culling strategies were simulated using these data. In addition to culling on maximum age, culling was either based on health alone, health and reproductive failure in one year (not pregnant) or health and reproductive failure in two consecutive years (not pregnant twice). The average herd age in the data sets reviewed under the actual culling strategies ranged from 4.58 to 6.73 yr and the average age of culled cows ranged from 5.41 to 9.94 yr. Description of the culling process as a Markov chain enables calculations of the age distribution at equilibrium by simple matrix operations, an advantage over the methods presently used. The scarcity of estimated age-specific probabilities of health and reproductive failure points to the need for more population analyses of beef cattle.

Age Factors↗
PubMed1989

Exponential pattern of cell age distribution in dividing cells of plant meristems.

In order to determine the pattern of cell age distribution in proliferating cells of Allium cepa roots we have measured by cytophotometry two cell size parameters, protein content and surface area projection, in cells that correspond to the entire proliferating population or only to the ana-telophase subpopulation. The size values of ana-telophase cells have been employed to construct theoretical size distributions for the entire proliferating cell population of the root meristem by assuming either a uniform or an exponential cell age distribution. Statistical comparison of theoretical distributions with the experimental one rules out a uniform cell age distribution and strongly favours an exponential age distribution similar to that found in bacteria.

Cell Division↗
PubMed1988

Prevalence of dominant mutations in Spain: effect of changes in maternal age distribution.

We studied the birth prevalence of autosomal dominant mutations in Spain and estimated how a decrease in maternal age distribution may lead to reduction in dominant mutations. The data were collected by the Estudio Colaborativo Español de Malformaciones Congénitas from April, 1976, to December, 1985. Among 553,270 liveborn infants monitored during the period, 66 infants with autosomal dominant conditions were identified. These included Apert, Crouzon, Hay-Wells, Treacher-Collins, Robinow, Stickler, Adams-Oliver, and the blepharophimosis syndromes, achondroplasia, cleidocranial dysostosis, and thanatophoric dysplasia. The overall rate of autosomal dominant conditions was 1.2 per 10,000 liveborn infants. Thirteen (20%) had an affected relative, and 52 (79%) had a negative family history. One case was excluded because of insufficient family data. The rate of autosomal dominant mutations was 0.9 per 10,000 liveborn infants, or 47 per 1 million gametes. A reduction in the maternal age distribution of mothers age 35 years and older from the current 10.8% to 4.9%, as in Atlanta, Georgia, would reduce the rate of Down syndrome in Spain by 33% and through a change in parternal age distribution may lead to a reduction in dominant mutations of about 9.6%. This suggests that a public health campaign to reduce older maternal age distribution in Spain may also lead to a reduction in dominant mutations and emphasizes the potential that a direct campaign for fathers to complete their families before age 35 years may have a small, but measurable, effect in the primary prevention of dominant mutations.

Adult↗
PubMed1985

[Principle of plotting the age distribution of persons with hereditary diseases at various ages of onset and differential mortality].

A method for ascertaining the mode of current age distributions is suggested for accurate quantitative assessment of some genetic parameters of hereditary diseases, such as age-specific penetrance, frequency of heterozygotes in the general population, fitness. The method is based on estimating the age-specific proportion of affected among the total number of heterozygotes, which seems more reasonable than the common methodology, considering the age-specific proportion of affected among all cases of the disease indicated.

Age Factors↗
PubMed1987

Age distribution of anginose mononucleosis.

The age distribution of anginose infectious mononucleosis in children was analysed retrospectively for the years 1966-85. During that period the disease became significantly more common in children of a young age and less common in older children. This shift could not be attributed either to socioeconomic conditions or to the diagnostic methods used.

Adolescent↗
PubMed1990

[A mathematical model of age distribution of malignant tumours mortality].

There was a tendency that the mortality of malignant tumours increased with age. In order to explore the law of this tendency, the data of malignant tumours mortality from disease monitoring points in Shandong Province were mathematically analogized, and the mathematical model of age distribution of malignant tumours mortality was established by using the exponential curve, y = 10a + bx. The model was also tested and verified by using national data, to observe the universal significance of the model. The model gave a theoretical account of the law of age distribution of malignant tumours mortality from a population, and provided an initial method to predict malignant tumours mortality. The increment quantity of malignant tumours mortality in various age groups when age increased one year could be calculated by using the differential equation from the exponential curve equation, y = 10a + bx. Further, "an increment multiple constant" of the increment quantity of malignant tumours mortality could be calculated. The constant could be used as an Index for comparison in risk degree and age distribution law of malignant tumours mortality among various age groups and the same age group in different periods, and provided leads for further research of the causes of malignant tumours.

Age Factors↗
PubMed1990

Changing paternal age distribution and the human mutation rate in Europe.

All available evidence indicates that the human mutation rate increases with paternal age. In developed countries, a reduction in the proportion of older parents is a common feature of the marked changes in parental age distribution that occur as a result of family planning. We have related the current paternal age distribution in the European countries for which data is readily available, to a derived curve for paternal age-specific relative mutation rate. The results indicate that, to the extent that it is dependent on paternal age, the mutation rate has decreased considerably in developed countries during the past 50 years. The human mutation rate is a dynamic entity, continuously changing in response to social conditions.

Adult↗
PubMed1991

The prevalence and age distribution of peripheral pulmonary hamartomas in adult males. An autopsy-based study.

This autopsy-based study defined the prevalence and age distribution of peripheral pulmonary hamartomas in 47,635 southern African miners examined between 1975 and 1988. The prevalence rate for white miners was 7.5/1,000 and for black miners 1.1/1,000. When directly standardised to the white men in the general population, the rates for white and black miners were 7.2 and 5.5/1,000, respectively. The prevalence of peripheral pulmonary hamartomas in both groups increased with age, from 0.8/1,000 in the third decade to 12.0/1,000 in the eighth decade. The study showed a much higher prevalence of peripheral pulmonary hamartomas for whites than previously reported. Furthermore, it documented the occurrence of these benign lung tumours in blacks, a fact that has previously been questioned. There appeared to be no significant difference in prevalence and age distribution between white and black miners, although the database for the black group was deficient for the later decades of life.

Adult↗
PubMed1989

Effect of maternal age distribution and prenatal diagnosis on the population rates of Down syndrome--a comparative study of nineteen populations.

We analyzed published data from 1980-85 on maternal age specific rates of Down syndrome in nineteen malformation monitoring systems. In the comparisons, we used maternal age specific Down syndrome baseline rates collected in Sweden using multiple sources and from a period before intense prenatal diagnosis. We supposed that no real maternal age specific risk difference exists between different populations, and that ascertainment of cases is independent of maternal age. With these suppositions, most programs had an ascertainment level of 70-90%, and some had about the same but none had a higher ascertainment level than that in the Swedish baseline. Marked differences in maternal age distribution in the populations studied resulted in a 12.3% standard deviation of the average population Down syndrome rate. The highest theoretical rate (estimated from actual maternal age distribution and Swedish baselines) was found in Spain (20% above average), the lowest in Czechoslovakia (24% below average). The estimated average effect of prenatal diagnosis was a decrease of only 6%, but in Denmark it was 25% and in Sweden and France:Paris 13%.

Adult↗
PubMed1992

[The relationship of clinical manifestations and age distribution in enterovirus infections--viral isolation and seroepidemiology in Aichi Prefecture].

We studied the epidemiology of enterovirus infection in Aichi Prefecture from 1985 to 1989. We examined the age distribution of aseptic meningitis patients (AM) and exanthematous disease patients (Ex) and a seroepidemiological study of echovirus type 7 (E7), E9, E18 and group A coxsackievirus type 9 (CA9), was performed. The results is as follows: 1) E7, E9, E18 and CA9 were isolated from AM and Ex but E6, E11 and group B Coxsackie viruses (CB) were isolated in fewer cases from Ex. 2) The AM was consistently increased from June to August. Whereas the Ex was seen in all seasons but a slight increase was noted between June to July, and enteroviruses (EV) isolation was increased in this season. 3) The AM occurred in 0 year olds and 4 year olds whereas the Ex was seen in 0 to 1 years. EV was mainly isolated from 0-1 year olds. 4) The relationship of clinical manifestations and age was very clear in E9 and E18, a higher proportion of children at 1 years or under were those of the Ex and most children of the latter part of 4 years were those of the AM. The Ex had the same results with E7 and CA9 but AM was increased in 0 years and 4 year olds. 5) We studied the age distributions of neutralizing antibodies against E7, E9, E18 and CA9. The positive rate of neutralizing antibody after prevalence rose between 2-5 years of age. There were few patients among the 2 to 3 year olds but the neutralizing antibody was raised in this age. I considered that reason the enteroviruses infected mainly the 2 to 6 year olds showing no clinical symptoms where as some of the 3 year olds had aseptic meningitis and some under 1 year had symptoms of exanthematous diseases.

Age Factors↗
PubMed1992

Supraventricular tachycardia mechanisms and their age distribution in pediatric patients.

To better define the natural history of supraventricular tachycardia (SVT) in young patients, age distribution of SVT mechanisms was examined in 137 infants, children and adolescents. Patients with a history of cardiac surgery or neuromuscular diseases were excluded. An electrophysiologic study was performed in each patient: transesophageal (110 patients) or transvenous (14 patients) or both (13 patients). Mechanisms were classified as SVT using accessory atrioventricular (AV) connection (SVT using accessory connection, including orthodromic and antidromic reciprocating tachycardia), primary atrial tachycardia (including chaotic, automatic and reentrant atrial tachycardia), and tachycardia due to reentry within the AV node. SVT using accessory connection occurred in 100 of 137 patients (73%) and was the most prevalent mechanism. Primary atrial tachycardia and reentry within the AV node were present in 19 of 137 (14%) and 18 of 137 (13%) patients, respectively. Using a multinomial logit model, relative probabilities for tachycardia mechanisms for 5 age groups--prenatal, less than 1, 1 to 5, 6 to 10 and greater than 10 years--were determined. Primary atrial tachycardia (11 to 16%) and SVT using accessory connection (58 to 84%) appeared throughout infancy, childhood and adolescence. On the other hand, tachycardia due to reentry within the AV node (0 to 31%) rarely appeared before age 2 years. Mechanisms of SVT appear to have age-dependent distributions. SVT using accessory connection is the most common mechanism in young patients. We speculate that the propensity to tachycardia due to reentry within the AV node occurs during postnatal development.

Adolescent↗
PubMed1977

The application of age distribution theory in the analysis of cytofluorimetric DNA histogram data.

Age distribution theory has been employed in a model to analyse a variety of histograms of the DNA content of single cells in samples from experimental tumours growing in tissue culture. The method has produced satisfactory correspondence with the experimental data in which there was a wide variation in the proportions of cells in the intermitotic phases, and generally good agreement between the 3H-thymidine labelling index and the computed proportion in S phase. The model has the capacity to analyse data from populations which contain a proportion of non-cycling cells. However, it is concluded that reliable results for the growth fraction and also for the relative durations of the intermitotic phase times cannot be obtained for the data reported here from the DNA histograms alone. To obtain reliable estimates of the growth fraction the relative durations of the phase time must be known, and conversely, reliable estimates of the relative phase durations can only be obtained if the growth fraction is known.

Cell Division↗
PubMed1990

The effect of nutritional status on the age distribution of dental caries in the primary teeth.

A cross-sectional study of dental caries in the primary teeth as a function of nutritional status was conducted on 1481 children one to 13 years old in Lima, Perú. Forty-one percent of the children were found to be chronically malnourished (stunted), 3% were acutely malnourished (wasted), and 5% were both stunted and wasted. A plot of decayed, extracted, and filled teeth (deft) vs. age resulted in a bell-shaped curve that was shifted to the right by 2.5 years for malnourished groups, compared with normal children (p less than 0.01). The shift to the right of the age distribution of caries was associated with a delay in both the eruption and exfoliation of the primary teeth in malnourished children. Peak caries activity was significantly higher in wasted and in stunted and wasted children, when compared with normal controls. It is concluded that malnutrition delayed tooth development, affected the age distribution of dental caries, and resulted in increased caries experience in the primary teeth.

Acute Disease↗