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PubMed1989

Poisson regression modeling of temporal variation in incidence of childhood insulin-dependent diabetes mellitus in Allegheny County, Pennsylvania, and Wielkopolska, Poland, 1970-1985.

Contradictory observations have accumulated regarding a secular trend and/or an epidemic pattern in the incidence of insulin-dependent diabetes mellitus. In this study, insulin-dependent diabetes mellitus incidence below age 15 years was examined in Allegheny County, Pennsylvania, and in Wielkopolska, Poland, two areas diverse in terms of their geography and average risk for this disease. Numerator data were extracted from individual patient records, and annual denominator data were available for the years 1970-1985. Poisson regression models were used to disentangle the contributions of country, race, sex, age, period, and cohort effects to the observed variation in incidence. Poles and Allegheny County nonwhites were at greatly and moderately reduced risk, respectively, relative to Allegheny County whites. An increase in risk with age was significant and proportional in all three groups. There was significant time variability in Wielkopolska, where an epidemic began in 1982 and continued through 1985. This was a period rather than a cohort phenomenon and was a result of a recent outbreak of the disease rather than a long-term trend. In Allegheny County, changes in risk over the 16-year period were insignificant, although incidence doubled among whites aged 0-9 years during 1982-1983. The Poisson regression modeling provided a quantification and formal comparison of determinants of the incidence of insulin-dependent diabetes mellitus.

Adolescent↗

PubMed1995

The radio-opacity of fishbones: a cadaveric study.

Lateral neck radiographs performed to localize impacted fishbones have a low sensitivity. The differing radio-opacities of the bones of various fish species may be a reason for this. A cadaver head and neck and the rib bones of 10 species of fish were used in this study. A laryngoscope was used to introduce a fishbone into the vallecula and then into the hypopharynx of the cadaver. A lateral radiograph was taken in each case. Ten control films were taken. The radiographs were independently reviewed by a consultant radiologist and otolaryngologist. The presence and position of any bone seen was noted. There was no inter-observer variation. All species of fishbone were visible. One bone was not seen by either observer. Visualization of fishbones is more dependent on position than their degree of radio-opacity. Routine radiography is recommended.

Animals↗

PubMed1975

Sex ratio and the sex composition of the existing sibs.

1. It is well established that p, the probability of a male birth, declines with birth order. It is suggested here that this decline occurs within individual sibships (Poisson variation). 2. Other workers have also offered good evidence that (at least in some samples) p correlates positively between adjacent births within sibships (Markov association). 3. The present paper suggests that in addition, some couples have higher values of p than others. In other words, there is Lexis variation in p between couples. It is estimated that this Lexis variation augments the variance (contingent on the Markov process above) by a value of less than 0-002. 4. Data on sex ratio by the sex composition of the pre-existing children are interpreted to support the author's hypothesis that coital rate of parents is related to the sex ratio of their children. 5. However if the decline in sex ratio with maternal age were entirely due to the concomitant decline in coital rate, the variation in p between couples seems greater than could be accounted for by the observed variation between couples in coital rate. It is concluded that sex ratio depends on other factors besides coital rate. 6. It is noted that (when sibship size and birth rank are controlled) MF birth intervals are particularly long, and FM birth intervals particularly short, MM and FF intervals being of intermediate length.

Age Factors↗

PubMed1989

Reliability of radiological measurements in the assessment of the child's hip.

We investigated the reproducibility of the various radiological methods of assessment of hip dysplasia by making 474 assessments of hips and quantifying the inter-observer and intra-observer variation. There was a wide range of variability between the readings made by different observers and by one observer on two occasions. A measurement of acetabular index has to be given a range of +/- 6 degrees in order to be 95% confident of including the true measurement. We found the most helpful measurements to be the acetabular index, up to the age of eight years; the centre-edge angle, over the age of five years; and Smith's c/b ratio and neck-shaft angle. We feel, however, that the change in value over a series of radiographs in the same child is much more valuable. Single readings of all the radiological measurements investigated in this study were unreliable.

Acetabulum↗

PubMed2000

Race, ethnicity and benign prostatic hyperplasia in the health professionals follow-up study.

PURPOSE: We examined whether the prevalence of benign prostatic hyperplasia (BPH) varies by racial or ethnic origin in a large cohort of American male health professionals. MATERIALS AND METHODS: Included in our study were 1,508 men who underwent surgery for BPH between 1986 and 1994, and 1,837 with high moderate to severe lower urinary tract symptoms assessed by the American Urological Association symptom index in 1992 or 1994. "Noncases" comprised 23,246 asymptomatic participants. Self-reported major ancestry was black in 201 men, Asian in 413, other origin in 604 and white in 25,373. White heritage was further classified as southern European in 6,408 men, Scandinavian in 2,951 and other white in 16,014. The relative risk of BPH and 95% confidence intervals (CI) adjusted for age, body mass index, alcohol consumption, smoking and physical activity were calculated by logistic regression. RESULTS: Black men were not at increased risk for BPH (relative risk 0.85, 95% CI 0.55 to 1.31) compared with white men. Asian men were less likely to have undergone BPH surgery (relative risk 0.41, 95% CI 0.21 to 0.82), although the relative risk for symptoms was similar to that of white men. White men whose major ancestry was southern European were at modestly higher risk for BPH surgery (relative risk 1.28, 95% CI 1.12 to 1.46) and symptoms (relative risk 1.34, 95% CI 1.20 to 1.50), whereas men of Scandinavian heritage were at slightly decreased risk for symptoms than those of other white heritages. CONCLUSIONS: Racial and ethnic variation is evident in the incidence of BPH surgery and symptom severity. Whether this observed variation reflects underlying biological phenomena rather than differences in symptom tolerance requires further exploration.

Adult↗

PubMed2005

Portal hypertensive gastropathy.

Portal hypertensive gastropathy (PHG) is the term used to describe the endoscopic appearance of gastric mucosa seen in patients with cirrhotic or non-cirrhotic portal hypertension with a characteristic mosaic-like pattern with or without red spots. The prevalence of PHG varies from 50% to 98%, this variation of the prevalence being perhaps related to patient selection, inter- and intra-observer variation and absence of uniform criteria and classification. About 8% of the upper digestive hemorrhages in the cirrhotic patients are secondary to PHG. There is no general consensus on the endoscopic classification of PHG (the most New Italian Endoscopy Club). The exact pathogenesis of PHG is not completely understood, but the portal hypertension is the main factor involved in its development and not the severity of the hepatic disease. Gastric Antral Vascular Ectasia (GAVE) is a term used for the typical endoscopic findings of red stripes, separated by normal mucosa, most frequently seen in the gastric antrum or proximal stomach. Current therapy of PHG includes beta blockers, somatostatin and derivates, endoscopic and surgical methods including hepatic transplantation.

Gastric Antral Vascular Ectasia↗

PubMed1990

Oxidative stress, DNA repair, and cancer susceptibility.

For several years, our laboratory has been interested in evaluating if DNA repair capacity in peripheral human mononuclear leukocytes (HML) might be utilized as a marker of susceptibility to cancer. We have tested our hypothesis by using two different estimates of DNA repair, namely, unscheduled DNA synthesis (UDS) and ADP-ribosyl transferase (ADPRT) activity. Both UDS and ADPRT are sensitive to regulation by oxidative stress, and these parameters are suppressed in patients with cancer of the breast, colon, or lung, or with the genetic predisposition to develop it. Here we have considered interindividual variation in prooxidant-induced DNA repair in HML by analyzing ADPRT responses in regard to (1) constitutive ADPRT levels, (2) the levels of DNA damage induced by different prooxidant generating systems, (3) the type of oxygen radical generated, and (4) the role of antioxidant defenses. Only the constitutive level of ADPRT responses could explain the variation observed on 50 subjects. These data support a regulatory role for endogenous host factor variation in ADPRT and the likelihood of involvement of genetic factors.

Adult↗

PubMed1990

Method for establishing serum ferritin reference values depending on sex and age.

A method is described for the establishment of reference values for serum ferritin depending on sex and age. The results obtained in a stratified random sample of 353 healthy individuals from the Portuguese population revealed that 23% of the variation observed on serum ferritin values was related to sex differences and 6% of the variation was explained by age differences. Furthermore, the effect of age was different in both sexes: serum ferritin values increase with age in females over 40 years and in males under 40. The minimum and maximum reference values were established for the different subgroups of subjects as follows: for females under 40 years and males over 40, reference values were considered as the 2.5 and 97.5 percentiles from the adjusted lognormal distribution; for females over 40 years and males under 40, reference values were considered as the exponential transformation of the upper and lower limits of the 95% prediction intervals for the log of serum ferritin for each particular age point.

Adolescent↗

PubMed1982

Variation in assessing sella turcica tomograms for pituitary microadenomas. The Pituitary Adenoma Study Group.

A multicenter study evaluated the extent of observer variation in interpretation of hypocycloidal polytomograms of the sella turcica in women with amenorrhea and/or galactorrhea, some of whom had surgically verified pituitary adenomas. Three physicians--2 neuroradiologists and 1 neurosurgeon--independently and without additional clinical information about the patients reviewed 45 sets of tomograms, 16 of which had originally been classified as abnormal, 23 as normal, and 6 as equivocal. Two or more of these physicians agreed with the original reading in 58% of all cases: in 81% of those originally read as abnormal, 56% of those originally read as normal, but in none of those originally read as equivocal. In 8 women with surgically confirmed pituitary abnormalities, readers' accuracy ranged from 50 to 88%. The physicians varied considerably in the proportion of tomograms read as normal (16 to 45%) or abnormal (38 to 71%), but overall, for only 11% of the tomograms was there no agreement among any of the 3 reviewers. The findings indicate that even among highly experienced physicians, there is considerable variation in the interpretation of polytomograms of the sella for women with amenorrhea and/or galactorrhea.

Adenoma↗

PubMedDate not supplied

Age trends of sibling resemblance for height, weight and BMI during growth in a mixed longitudinal sample from Sarsuna-Barisha, India.

BACKGROUND: Even though some studies have considered that sibling resemblance remains constant throughout the life cycle, several investigations emphasize the importance of age and its interactions with genetic and environmental factors in determining sibling similarity in several bodily traits. In fact, the study of age changes in familial resemblance is of great importance for the analysis of certain sources of variation observed in growth processes. AIM: The study examined sibling resemblance for height, weight and body mass index (BMI) in a mixed longitudinal sample from West Bengal, ages 2-19 years, in order to analyse the variations with age of the sibling resemblance for these phenotypes during growth. SAMPLE AND METHODS: Two hundred and forty-five brothers and 213 sisters from 138 middle-class nuclear families living in a semi-urban area of South Kolkata, India were analysed. The analysis of sibling resemblance was performed through correlations estimated by the maximum-likelihood method. The patterns of different trends of sibling resemblance with age were examined by fitting a cubic non-linear regression to the observed correlations. RESULTS: The results show clear variations with age in the sibling resemblance for the traits height and weight, though to a lesser extent for BMI. In general, we found the highest correlation values during the period of infancy, a remarkable decrease during puberty, and a trend of increase towards the end of the growth cycle. CONCLUSION: The study confirms the effect of age on the degree of similarity among siblings for height, weight and BMI in the sample. The sharp decline of correlation at adolescence can be interpreted in terms of the individual variation in age of reaching the adolescent growth spurt.

Adolescent↗

PubMed2004

Phenological synchrony affects interaction strength of an exotic weevil with Platte thistle, a native host plant.

Phenological synchrony of a consumer population with its resource populations is expected to affect interaction intensity. We quantified phenological variation and synchrony of populations of an invasive Eurasian flower head weevil, Rhinocyllus conicus, that consumes florets, ovules, and seeds of developing flower heads of a native North American thistle, Cirsium canescens, in Sand Hills prairie in Nebraska, USA. Variation in timing of adult activity among weevil populations was larger than variation in timing of flower head development among C. canescens populations, and it drove the observed variation in the phenological synchrony between weevil and host plant populations. Furthermore, the degree of phenological synchrony between populations was significant in explaining variation in weevil egg load on the newly acquired host plant. Because population growth of C. canescens is limited by predispersal seed losses to floral herbivores, variation in the synchrony of herbivore and plant flowering will affect the density of the plant population. These results provide strong quantitative support for the hypothesis that the synchrony of insect activity with plant resources can determine the magnitude of impact of floral herbivores on their host plant populations.

Adaptation, Physiological↗

PubMed1992

A novel hypothesis of lipofuscinogenesis and cellular aging based on interactions between oxidative stress and autophagocytosis.

Based on a series of experiments, using cultured postmitotic neonatal rat cardiac myocytes as a model system, we present a novel hypothesis of lipofuscin formation. This hypothesis proposes that lipofuscin is formed within secondary lysosomes due to an interplay of two processes, the production of partially reduced oxygen species by mitochondria and the autophagocytotic degradation within secondary lysosomes. Specifically, it is proposed that H2O2 generated by mitochondria and other organelles permeates into the lumen of secondary lysosomes, which contain iron derived from cellular structures undergoing intralysosomal degradation. The interaction between reactive ferrous iron and H2O2 results, via Fenton-type mechanisms, in the generation of hydroxyl free radicals (OH), inducing lipid peroxidation and eventually leading to intermolecular cross-linking and lipofuscin formation. Additionally, mitochondria undergoing intralysosomal decomposition might continue for a certain period to produce superoxide anion radicals (O2-) and thus also H2O2. This model of lipofuscinogenesis could satisfactorily explain the variations observed in the rates of lipofuscinogenesis among different postmitotic cell types in various species. Such variations might arise from a variety of factors including differences in the efficiency of the 'anti-oxidative shield', rate of H2O2 generation, amount of chain-breaking antioxidants, mode of intralysosomal iron chelation, rate of autophagocytosis as well as degree of efficiency of the intralysosomal hydrolytic enzymes.

Animals↗

PubMed1988

Persistent free radicals in the smoke of common household materials: biological and clinical implications.

We have detected free radicals in the gas-phase smoke resulting from the combustion of several household materials. Materials were pyrolyzed by rapid heating in a quartz ignition tube in a flowing air stream. The filtered smoke was bubbled into a dodecane solution of alpha-phenyl-N-t-butylnitrone (PBN), and the resulting nitroxide radicals were detected by electron spin resonance. Cellulosic materials (birch plywood, cellulose, 1R1 research cigarette tobacco, and yellow pine) and dried exterior paint produce about the same yield of trapped radicals. The smoke from polyethylene and rubber produce approximately 2-fold more radicals than the smoke from the cellulosic materials. Nylon smoke yields about 10-fold less radicals than the cellulosic materials. The smokes from polyvinyl chloride and polytetraflouroethylene do not produce detectable spin adducts of PBN by this method. Where radicals were trapped, oxygen-centered spin adducts predominated; lesser amounts of carbon-centered spin adducts and an oxidation product of PBN were observed. Different oxygen-centered radicals were detected from different materials, as judged from the variation observed in the hyperfine splitting constants of the principal spin adducts. When cellulose smoke is dissolved in solution, radicals continue to be produced for at least 20 min, suggesting the production of a metastable species in the gas phase that decomposes to form radicals in solution.

Cellulose↗

PubMed1998

Improving survival of melanoma patients in Europe since 1978. EUROCARE Working Group.

Within the EUROCARE study 45 cancer registries have contributed survival data on 3.5 million cancer sufferers within 17 countries in Europe. This paper reports on survival in 16,113 cutaneous malignant melanoma cases diagnosed between 1985 and 1989. Relative survival rates were calculated according to the Hakulinen computer program with data stratified according to country, age group and period of diagnosis. Relative 5-year survival was higher in women (81%) than in men (69%) but there was wide variation in relative survival across Europe at both 1 and 5 years, ranging at 5 years between 54 and 89%. At both 1 and 5 years, survival was lowest in the Eastern countries. Between 1978 and 1989 there was an improvement in survival rates probably attributable to the detection of increasing proportions of better prognosis, thinner tumours. In the younger age groups, this may be related to public awareness campaigns. The discrepancy in survival between men and women also narrowed. The single most important prognostic factor is the depth of invasion at diagnosis and there is some evidence that underlying variation in stage at presentation as well as histological type accounts for much of the observed variation in survival.

Adolescent↗

PubMed2001

Diffuse damage accumulation in the fracture process zone of human cortical bone specimens and its influence on fracture toughness.

This study was concerned with the mechanics and micromechanisms of diffuse (ultrastructural) damage occurrence in human tibial cortical bone specimens subjected to tension-tension fatigue. A nondestructive technique was developed for damage assessment on the surfaces of intact compact tension specimens using laser scanning confocal microscopy. Results indicated that diffuse damage initiates as a result of fractures in the inter-canalicular regions. Subsequent growth of those microscopic flaws demonstrated multiple deflections from their paths due to 3D spatial distribution of microscopic porosities (lacunae-canalicular porosities) and the stress-concentrating effects of lacunae. Damage dominating effects in the early stages of fatigue had been verified by the observed variations of the fracture toughness due to artificially induced amounts of damage. Toughening behavior was observed as a function of diffuse damage.

Journal Article↗

PubMed1975

Language boundaries and biological differentiation of Bougainville: multivariate analysis of variance.

Blood genetic and antropometric data on Melanesians from Bougainville, Papus New Guinea, are analyzed by random-effects analysis of variance to partition the observed variation into components for the individuals, village, and language group level. Both clinial and unpatterned group differences exist. The differences between language groups appear to be substantial, even when the results are corrected for clinal effects. The amounts of variation of each level correspond roughly to a similar analysis of heterozygosity in blood polymorphisms. Observed current migration figures suggest that language and village constitute a 2-fold hierarchical subdivision of the breeding system, and this analysis shows probable random drift effects between groups at both the village and language level. Both language and genetic constitution of these villages are the result of differentiation in place.

Analysis of Variance↗

PubMed1999

Perturbation of radiotherapy beams by radiographic film: measurements and Monte Carlo simulations.

Radiographic film is an established practical tool used in the measurement of the dose distribution for radiotherapy purposes. The accuracy and reproducibility of film optical density as an indicator of dose has been associated with several factors including photon energy, processing conditions and film plane orientation. Few studies have investigated the factors causing variability in film dosimetry, due to the difficulty of separating the individual contributions. The effect that a sheet of radiographic film in a water phantom has on its response to a 6 MV photon and a cobalt-60 teletherapy beam, when orientated perpendicular and parallel to the beam central axis, is reported. Monte Carlo generated spectra were used to calculate collision kerma (Kcoll) for water and film elements. Measured and calculated results indicate a potential over-response at 25 cm depth of the order of 14 +/- 2.4% and 18 +/- 6.0% respectively for 6 MV photons and 15 +/- 3.4% and 32 +/- 4.5% respectively for a cobalt beam. For film exposed parallel as compared to perpendicular to the central axis of the beam, the calculated results suggest an explanation in terms of the predominantly forward directed secondary electrons for the measured difference in film response at depth. It is proposed that the difference in response of the parallel as compared to perpendicular exposed film be due to the predominantly 'upstream' photon interactions giving rise to energy deposition in film. The simulations indicate that the variation with depth of relative energy imparted in film and water elements correlates with the observed variation in film response with depth.

Energy Transfer↗

PubMed1990

Evidence of extensive genetic exchange in the rp49 region among polymorphic chromosome inversions in Drosophila subobscura.

Restriction map variation in 107 lines extracted from two natural populations of Drosophila subobscura was investigated with seven four-nucleotide-recognizing enzymes in a 1.6-kb region including the rp49 gene, that is located very close to the proximal breakpoint of inversion O3. Fourteen restriction site and 8 length polymorphisms, resulting in 73 haplotypes, have been identified. Estimated heterozygosity per nucleotide, pi = 0.0045, is comparable to the average nucleotide variation observed in Drosophila melanogaster. Because of the location of the rp49 region in D. subobscura, variation in three different gene arrangements-Ost, O3 + 4 and O3 + 4 + 8-has been compared. Out of 14 restriction site polymorphisms, 3 are shared by Ost, O3 + 4 and O3 + 4 + 8, and 3 additional ones are shared by Ost and O3 + 4, evidencing extensive genetic exchange among these polymorphic inversions. In agreement with previous data, the higher level of variation of O3 + 4 (as measured by haplotype diversity and nucleotide variation) suggests that O3 + 4 may be ancestral in relationship to extant gene arrangements.

Animals↗