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PubMed1998

Modelling the prevalence of Echinococcus and Taenia species in small ruminants of different ages in northern Jordan.

A base-line survey of Echinococcus granulosus, Taenia hydatigena and T ovis were undertaken in order to investigate the transmission dynamics of these parasites in northern Jordan. Intensity of E. granulosus infection, in sheep, increased with age in a linear fashion whilst the asymptotic prevalence was one. This implied that E. granulosus is in an endemic steady state with no evidence of protective immunity in the intermediate host. The mean number of cysts increased by 1.66 per year with approximately 0.320 infections per year, each infection consisting of 598 eggs to produce 5.2 cysts. The basic reproduction ratio (R0) was estimated to be 1.5-1.8. A similar pattern was suggested with E. granulosus in goats but the infection pressure appeared to be lower with only 0.128 cysts per year. Although infection in goats appeared to be endemic there was some evidence of departure from the model which might indicate that the model needs adjusting for this species. In the case of T. hydatigena the host age-intensity helminth distribution indicated that this parasite was hyperendemic in both sheep and goats, implying regulation by intermediate host immunity. Consequently, R0 was determined from asymptotic prevalence curves for T hydatigena and was calculated to be 4.0 and 3.1 in sheep and goats, respectively. The lower R0 in goats, together with the higher asymptotic age-intensity and age-prevalences, indicates that goats acquire immunity more slowly to T hydatigena in comparison to sheep. Taenia ovis was not detected in any animals.

Animals↗
PubMed2002

Incidence of breast cancer on Crete, 1994-1995.

The aim of this study was to present epidemiological results relating to malignant neoplasms of breast using primary data from the island of Crete, Greece, 1994-1995. The patients were all female residents of Crete with breast cancer first diagnosed during 1994 and 1995, 208 and 207 new incident cases, respectively. The data were collected and analysed by the Cancer Registry of Crete (CRC). Direct age-standardised rates (ASR) for incidence and cumulative risk (to age 75 years) were calculated for Crete as a whole. Standardised incidence ratios (SIR) were calculated for the 20 provinces (administrative regions); these were also smoothed using Bayesian methods. The ASR for incidence per 100000 person-years was 70.6. The truncated rate (age 40 years and above) was 153.7. The SIR for the 20 provinces showed no marked variations, with three exceptions, two of which had ratios higher than 1 and one lower. Bayesian smoothing of provincial incidence rates showed that throughout Crete, the risk of breast cancer shows considerable uniformity. The incidence rate of breast cancer on Crete is higher than that of Greece overall, and is comparable with other southern European countries. A possible explanation is that the published incidence for Greece may be an underestimation of the true rate. The small variability in breast cancer incidence within Crete probably reflects the homogeneity of the population and environmental and social conditions.

Adult↗
PubMed2001

Likelihood maximization for list-mode emission tomographic image reconstruction.

The maximum a posteriori (MAP) Bayesian iterative algorithm using priors that are gamma distributed, due to Lange, Bahn and Little, is extended to include parameter choices that fall outside the gamma distribution model. Special cases of the resulting iterative method include the expectation maximization maximum likelihood (EMML) method based on the Poisson model in emission tomography, as well as algorithms obtained by Parra and Barrett and by Huesman et al. that converge to maximum likelihood and maximum conditional likelihood estimates of radionuclide intensities for list-mode emission tomography. The approach taken here is optimization-theoretic and does not rely on the usual expectation maximization (EM) formalism. Block-iterative variants of the algorithms are presented. A self-contained, elementary proof of convergence of the algorithm is included.

Algorithms↗
PubMed2001

The defibrillation system of basic emergency medical technicians in Japan: a comparison with other systems from a 14-year review of out-of-hospital cardiac arrest reports.

Although seven years have passed after basic emergency medical technician (EMT) defibrillation system was introduced in Japan, the overall survival for out-of-hospital cardiac arrest (OHCA) remains poor. We investigated factors leading to such an unanticipated result in Japan by comparing the data of OHCA in Japan with those in other countries. We obtained population-based OHCA data from three communities in Japan. We also performed a comprehensive literature and manual search to identify reports that included rates for incidence and survival or provided sufficient data for the calculation of these rates of OHCA. Statistical analysis was performed to compare survival and incidence rates between the communities. We identified 36 articles from 16 countries by a comprehensive literature search. There was no significant difference in incidence and survival rates among communities in Japan. Although the incidence rate of collapse-witnessed OHCA with ventricular fibrillation (VF) was much lower in Japan than western countries, the proportions of survival from it were comparable to those. Basic-EMT defibrillation system in Japan has yielded excellent result in terms of the survival of VF cases. However, much lower proportion of VF to all cases is responsible for lower overall rates of survival from OHCA in Japan.

Chi-Square Distribution↗
PubMed1990

[Distribution pattern of Dirofilaria immitis microfilariae in peripheral blood of a dog and their intake by mosquitoes].

Experiments were made in which Aedes aegypti mosquitoes fed on a dog infected with Dirofilaria immitis, in order to determine the distribution pattern of microfilariae (Mf) in the dog's periphery blood and the number of Mf taken by the mosquitoes. Mosquitoes fed on an anesthetized dog at some 50 shaved skin spots and they were weighed immediately before and after feeding. This enabled us to examine not only the Mf number taken by each mosquito but also the Mf intake density in terms of Mf number per mg of blood. The Mf intake density showed a wide variation at the different parts of the dog's body, and the frequencies of Mf showed uneven distributions which were fitted best by the negative binomial. Significant differences were detected in the Mf intake density at different parts of the skin, but these differences were concluded as a non-consistent result because a similar result was not reproduced in the next experiment. It was presumed that not only the Mf number per mosquito but also the Mf intake density increased as the blood intake by the mosquitoes increased. This increase of both the Mf number per mosquito and the Mf intake density was also supported by another experiment in which mosquitoes were fed at the same skin spots consecutively one after another.

Aedes↗
PubMedDate not supplied

[Identification of radiation, chemical and combined effects on natural populations of aquatic organisms].

Approaches to the identification of radiation, chemical and combined effects on natural populations of aquatic organisms are proposed. These approaches are based on generalization of our previous experimental data concerning separate and combined effects of ionizing radiation and chemical mutagens (heavy metals and chlororganic compounds) on crustaceans and fishes embryos, as well as on results of field studies carried out before and after the Chernobyl NPP accident. For the identification of damaged factors it is proposed to use the following criteria: a comparison of cytogenetic effects in mutagen equivalent doses, a distribution of chromosome aberrations in cells and a number of aberrations per an aberrant cell.

Animals↗
PubMedDate not supplied

[The manifestations of a scarlatina epidemic process in a large city and their interpretation].

The average morbidity level in scarlet fever for the period of 1972-1990 in Moscow was 230.9 cases per 100,000 of the population and the annual economic damage was 2-2.5 million rubles. The highest morbidity rate values were registered among children attending children's institutions, and in this group among children aged 3-6 years. Cohort and disperse analysis revealed that age-dependent fluctuations of morbidity rate had a regular character and significantly differed. An increase in scarlet fever morbidity was registered simultaneously with elevated levels of morbidity in tonsillitis and acute respiratory diseases and occurred several weeks after a rise in tonsillitis morbidity. Contamination with group A streptococci was higher among "organized" children of preschool age than among other groups of the population. T serovars 4/28, 8/29/Imp.19, 3/13/B3254 and 1, constituting 44% of all isolated Streptococcus pyogenes strains, and OF type 2 (44%) and 22 (20%) occurred most frequently. Among the strains isolated from patients T-4 and OF-2 types prevailed.

Adolescent↗
PubMed1996

Nonfatal and fatal firearm injuries in a rural county.

OBJECTIVE: To measure the incidence of fatal and nonfatal firearm injuries in a rural setting. DESIGN: A prospective, population-based surveillance system using information from medical and legal records, newspapers, and members of the community. SETTING: A rural county in North Carolina. MAIN OUTCOME MEASURES: Incidence rates and case-fatality ratios (fatal:non-fatal). RESULTS: Of the 114 firearm injuries detected by the surveillance system from January 1, 1990, through December 31, 1991, nearly two thirds were nonfatal. The overall age-adjusted annual incidence of firearm injuries was 66.4 per 100 000 population, and the incidence of nonfatal firearm injuries was 41.2 per 100 000 population. Subgroup annual incidence rates were greatest for African Americans. The overall case-fatality ratio was 1:1.8 (fatal:nonfatal). CONCLUSIONS: Incidence rates and case-fatality ratios for firearm injury in this rural setting were greater than expected, based on national estimates, perhaps because of greater proportions of rifle injuries and self-inflicted injuries.

Accidents↗
PubMed1995

Homicide and other injuries as causes of maternal death in New York City, 1987 through 1991.

OBJECTIVES: We attempted to document the role of homicide and other injuries as causes of maternal death and to compare the risk of fatal injury among pregnant women with that in the general population. STUDY DESIGN: We reviewed New York City medical examiner records of 2331 women aged 15 to 44 years who died of injury in 1987 through 1991. Pregnancies were identified from autopsy information. RESULTS: A total of 115 (39%) of 293 deaths in currently or recently pregnant women were attributable to injury. These 115 deaths included homicide (63%), suicide (13%), motor vehicle crashes (12%), and drug overdoses (7%). Minority women were overrepresented among the injury deaths (black 53%, Hispanic 24%, white 19%). Recent substance use was documented in 48% of the injury deaths. Pregnancy was documented on only 35% of the 115 death certificates. The risk of fatal injury is similar for currently pregnant women and for women in the general population, except for an increased risk of homicide among pregnant black women. CONCLUSIONS: Homicide and other injuries are major contributors to maternal mortality and should be (but rarely are) included routinely in maternal mortality surveillance systems. Prenatal and postpartum clinic visits represent an ideal time to implement interventions to prevent injuries among pregnant women.

Accidents, Traffic↗
PubMed2001

Study of 2708 heroin-related deaths in north-eastern Italy 1985-98 to establish the main causes of death.

AIMS: To ascertain the causes of deaths among a very large cohort of heroin injecting drug users (IDUs) who, from 1985 to 1998, attended 36 Public Health Authority Centres for Drug Users (PCDUs) in north-eastern Italy. DESIGN: Retrospective analysis of data, obtained from the Annual Register of each Centre and the Municipal Registry Office of each local health district. SETTING: Thirty-six PCDUs in north-eastern Italy and Medical Service for Addictive Disorders of the University of Verona. PARTICIPANTS: All IDUs who had sought medical care at least once in the PCDUs during the study period. FINDINGS: Of 2708 deaths, overdose was found to be the major cause (37%), followed by AIDS (32.5%) and road accidents (9.4%). The percentage of deaths due to AIDS increased steadily from 2.7% in 1985 to 42.2% in 1996, and then decreased to 16.9% in 1998. Deaths due to overdose remained almost constant. The average age of death per year rose from 26 in the mid eighties to 34 in 1998. The mortality rate among IDUs proved much higher compared to the general population of the same age (13-fold, 95% CI, 11.3-14.6). The proportion of all deaths attributable to regular use of illegal opiates in the 15-34 age group in the general population in 1991 was 16%. HIV prevalence was not a significant factor in suicides and deaths by overdose. CONCLUSIONS: The mortality rate was 13 times greater than in the general population. To be female and to have dropped out of any kind of treatment proved an important risk factor for overdose. The fall in deaths from AIDS enhances the problem to prevent and treat HCV infection. Decisions in drug projects, in research and in training should be influenced by the strikingly high percentage of deaths due to drug use.

Accidents, Traffic↗
PubMed2001

Age period cohort analysis of time trends in regional mortality rates in England, Wales and Scotland.

Previous studies have demonstrated regional variation in mortality rates, this reducing for younger but not older individuals. However, it has not been clear from such studies whether or not the overall findings can or cannot be attributed to particular regions that may have abnormal patterns of change over time. We analyse mortality rates by region using data from the census years from 1931 until 1991 for adults. Age period cohort models, based on the local 'curvatures', are used to describe the changes in the rates. We also use estimable contrasts to compare the later periods with the earlier periods and to compare pre- and post-war cohorts. There is strong evidence that the changes in the mortality rates are associated with non-linear period and cohort effects. There is no evidence that these curvatures vary over regions. There is evidence that the curvatures are not the same among men and women. Among women there is evidence that there is a change in trend in the periods from 1961 to 1991 compared with the trend in the earlier periods from 1931 to 1951, such that the reduction in the mortality rates with time are slowing down for women. Among men who had higher mortality rates, there is not so much evidence of a slowing down of the reduction. Post-war cohorts of women from 1941 onwards are enjoying a reduction in mortality compared with the cohorts from 1901 to 31, while among men there is no evidence of a change in mortality trends among younger cohorts. Changes in the mortality rates over regions have come about from different long-term temporal trends in the regions rather than abrupt changes taking place at different times in different regions. The general convergence of mortality rates over regions over time with a consequent reduction in regional variance is masked by two regions, Scotland and East Anglia. These regions appear to differ from the regions as a whole in the relationship of mortality to age at a given period and in the reduction of mortality over time (drift), Scotland having a higher mortality, especially at younger ages, and lower downward trend, and East Anglia vice versa.

Adolescent↗
PubMed1997

Cancer incidence and age at northern migration of African Americans in Illinois, 1986-1991.

We compared the proportional cancer incidence of Illinois-born African Americans with those who migrated to Illinois from southern US states as children and adults, and with African American residents of the south. Adult Illinois residents, born between 1913 and 1966, who were diagnosed with cancer from 1986 through 1991 were classified by both birthplace and the state and year their social security number was assigned to determine their migration status: native, early (as child) migrant or late (as adult) migrant. African Americans of Atlanta were used to represent southern homeland ratios. Only lung cancer in African American females showed a statistically significant trend among the four groups, with Illinois native having the highest ratio. Although no trend was identified, Illinois natives had statistically significantly different ratios than both migrant groups and the southern homeland for cancers of the oral cavity (males), colon (females) and leukemias (females). The data also suggested that US regional differences in cancer ratios among African Americans exist (cancers of the prostate and testis, and in females, cancers of the oral cavity, esophagus and kidney), and among those African Americans that migrate to the north from the south, some cancer ratios also change (in males, cancers of the stomach colon, bladder and myeloma and in females, rectal cancer). Further, evidence was found in some cancer sites for the effect of the timing of northern migration on cancer risk (cancer of the rectum (males), liver (both sexes), and in females, cancer of the breast, stomach and nervous system).

Adult↗
PubMed2003

Are changes in mortality from stroke caused by changes in stroke event rates or case fatality? Results from the WHO MONICA Project.

BACKGROUND AND PURPOSE: Mortality from stroke has been declining over recent decades in most countries, except in Eastern Europe. In this analysis, based on the World Health Organization Monitoring Trends and Determinants in Cardiovascular Disease (WHO MONICA) Project, we explored to what extent these trends are due to changes in stroke event rate and to changes in case fatality. METHODS: The WHO MONICA Project collected standardized data from 14 populations in 9 countries. All acute strokes occurring in men and women 35 to 64 years of age were included. Registration was carried out between 1982 and 1995, resulting in time spans from 7 to 13 years. Trends in event rates and case fatality were calculated as average annual percentage change. RESULTS: Up to 6-fold differences were observed in stroke mortality. Mortality declined in 8 of 14 populations in men and in 10 of 14 populations in women. An increase in mortality was observed in Eastern Europe. In the populations with a declining trend, about two thirds of the change could be attributed to a decline in case fatality. In populations with increasing mortality, the rise was explained by an increase in case fatality. CONCLUSIONS: In most populations, changes in stroke mortality, whether declining or increasing, were principally attributable to changes in case fatality rather than changes in event rates. Whether this was due to changes in the management of stroke or changes in disease severity cannot be established on the basis of these results.

Adult↗
PubMed1998

Mortality in persons with developmental disabilities after transfer into community care.

More than 2,000 persons with developmental disabilities have been transferred from California state institutions into community care in recent years. We investigated whether this has been accompanied by a change in mortality rates, using data on 1,878 clients moved since April 1993. Mortality rates were compared to those expected for comparable persons in institutions. Risk-adjusted mortality rates for movers exceeded institutional rates by 51%, p < .05. After removal of cancer deaths in both groups, this increased to 67%. The effect was largest shortly after the move and in the subjects who had moved most recently. The deinstitutionalization process in California appears to have resulted in a substantial increase in mortality, indicating the need to ensure continuous, consistent, and competent medical care and supervision in the community.

Activities of Daily Living↗
PubMed2004

A scale invariant clustering of genes on human chromosome 7.

BACKGROUND: Vertebrate genes often appear to cluster within the background of nontranscribed genomic DNA. Here an analysis of the physical distribution of gene structures on human chromosome 7 was performed to confirm the presence of clustering, and to elucidate possible underlying statistical and biological mechanisms. RESULTS: Clustering of genes was confirmed by virtue of a variance of the number of genes per unit physical length that exceeded the respective mean. Further evidence for clustering came from a power function relationship between the variance and mean that possessed an exponent of 1.51. This power function implied that the spatial distribution of genes on chromosome 7 was scale invariant, and that the underlying statistical distribution had a Poisson-gamma (PG) form. A PG distribution for the spatial scattering of genes was validated by stringent comparisons of both the predicted variance to mean power function and its cumulative distribution function to data derived from chromosome 7. CONCLUSION: The PG distribution was consistent with at least two different biological models: In the microrearrangement model, the number of genes per unit length of chromosome represented the contribution of a random number of smaller chromosomal segments that had originated by random breakage and reconstruction of more primitive chromosomes. Each of these smaller segments would have necessarily contained (on average) a gamma distributed number of genes. In the gene cluster model, genes would be scattered randomly to begin with. Over evolutionary timescales, tandem duplication, mutation, insertion, deletion and rearrangement could act at these gene sites through a stochastic birth death and immigration process to yield a PG distribution. On the basis of the gene position data alone it was not possible to identify the biological model which best explained the observed clustering. However, the underlying PG statistical model implicated neutral evolutionary mechanisms as the basis for this clustering.

Algorithms↗
PubMed1999

Long-term potentiation and depression induced by a stochastic conditioning of a model synapse.

Protracted presynaptic activity can induce long-term potentiation (LTP) or long-term depression (LTD) of the synaptic strength. However, virtually all the experiments testing how LTP and LTD depend on the conditioning input are carried out with trains of stimuli at constant frequencies, whereas neurons in vivo most likely experience a stochastic variation of interstimulus intervals. We used a computational model of synaptic transmission to test if and to what extent the stochastic fluctuations of an input signal could alter the probability to change the state of a synapse. We found that, even if the mean stimulation frequency was maintained constant, the probability to induce LTD and LTP could be a function of the temporal variation of the input activity. This mechanism, which depends only on the statistical properties of the input and not on the onset of additional biochemical mechanisms, is not usually considered in the experiments, but it could have an important role to determine the amount of LTP/LTD induction in vivo. In response to a change in the distribution of the interstimulus intervals, as measured by the coefficient of variation, a synapse could be easily adapted to inputs that might require immediate attention, with a shift of the input thresholds required to elicit LTD or LTP, which are restored to their initial conditions as soon as the input pattern returns to the original temporal distribution.

Long-Term Potentiation↗
PubMedDate not supplied

[Probabilistic models to analyze psychiatric contacts].

OBJECTIVE: To present three probabilistic models (Poisson, negative binomial, Waring) to analyze the distribution of the number of contacts of patients followed using a psychiatric case register. DESIGN: Longitudinal to obtain the distribution of the number of contacts (during 91 days following that of the first contact) observed on patients followed using the South-Verona Psychiatric Case Register during the period 1/1/79-31/12/91. RESULTS: There were a total number of 6913 contacts on 3454 subjects. The chi-square test for the goodness of fit yields a significant result both for the Poisson distribution (3580 with 6 degrees of freedom, p < 0.001) and for the negative binomial distribution (65.47 with 18 degrees of freedom, p < 0.001); on the other hand a non significant result was obtained for the Waring distribution (25.31 with 19 degrees of freedom, p = 0.151). CONCLUSIONS: The Poisson distribution gave a very poor fit for the distribution of contacts. The negative binomial distribution could be employed to analyze the pattern of contacts when the right tail of the distribution is not important. The Waring distribution is the best of the three presented. Moreover, the variance of the Waring distribution can be decomposed in three components: a random component, a component which accounts for endogenous factors and another component which accounts for esogenous factors. Therefore the Waring distribution is useful when one wants to make comparisons between psychiatric case registers of the same country or of different countries.

Humans↗
PubMed1999

Effect of newborn screening for congenital adrenal hyperplasia.

OBJECTIVE: To compare the incidence of diagnosis and morbidity in newborns who were screened with newborns who were not screened for congenital adrenal hyperplasia (CAH). DESIGN: A retrospective cohort study. SETTING: Arkansas, Oklahoma, and Texas. PATIENTS: An unscreened population in Arkansas and Oklahoma (n = 400118) was compared with a screened population in Texas (n = 1613378) during a 5-year period. Simultaneous data were collected on the incidence of diagnosis and associated morbidity in patients with CAH. MAIN OUTCOME MEASURES: Diagnosis of CAH, age (in days) at diagnosis, and frequency and length of initial hospitalization. RESULTS: The incidence of diagnosis of classic CAH per 100000 newborns in the unscreened cohort (5.75) and in the screened cohort (6.26) was similar (relative risk, 0.92; 95% confidence interval, 0.58-1.44). The unscreened group had 0.73 fewer male newborns with salt-wasting CAH diagnosed per 100000 newborns (relative risk, 0.73; 95% confidence interval, 0.35-1.56). The median age at diagnosis was 26 days for male newborns with salt-wasting CAH in the unscreened cohort vs 12 days in the screened cohort (z = 2.49; P = .01). Male newborns with simple-virilizing CAH and newborns with nonclassic CAH were detected only in the screened cohort. CONCLUSIONS: There was not a statistically significant (P = .73) increase in the diagnosis of salt-wasting CAH in the screened cohort. Male newborns benefited as a result of significantly (P = .01) earlier diagnosis, reduced morbidity, and shorter lengths of hospitalization. Large collaborative studies or meta-analyses are needed to determine the life-saving benefits of screening.

17-alpha-Hydroxyprogesterone↗