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At least 487 records · Page 27Linked to original sources
PubMed1992

Radiation-related ophthalmological changes and aging among Hiroshima and Nagasaki A-bomb survivors: a reanalysis.

The relationship of ionizing radiation to the age-related ophthalmological findings of the 1978-1980 ophthalmological examination of A-bomb survivors of Hiroshima and Nagasaki has been reanalyzed using DS86 eye organ dose estimates. The main purpose of this reevaluation was to determine whether age and radiation exposure, as measured using the recently revised dosimetry information (DS86), have an additive, synergistic, or antagonistic effect. The data in this study are limited to axial opacities and posterior subcapsular changes, for which a definite radiation-induced effect has been observed in Hiroshima and Nagasaki A-bomb survivors. The best model fitting for axial opacities gives a significant positive effect for both linear dose and linear age-related regression coefficients and a significant negative effect for an interaction between radiation dose and age. Such a negative interaction implies an antagonistic effect in that the relative risks in relation to radiation exposure doses become smaller with an increase in age. On the other hand, the best-fitting relationship for posterior subcapsular changes suggested a linear-quadratic dose and linear age-related effect. The estimate of the quadratic dose coefficient shows a highly negative correlation with age, but the negative quadratic dose term is extremely small and is of little biological significance.

Adult↗
PubMedDate not supplied

[Reanalysis of mortality in a petrochemical plant producing vinyl chloride and polyvinyl chloride].

OBJECTIVE: To study cancer mortality among main subgroups of workers employed in VC/PVC production potentially exposed to toxics and carcinogens. MATERIALS AND METHODS: We reanalyzed the mortality of 1,658 males (follow up 1972-1995; 35,626 person years; 170 deaths) by Poisson regression, adjusting for age, age at hiring, calendar period, length of exposure and latency. We calculated the relative risks (RR) and the 95% confidence intervals (CI) for PVC baggers (n. = 197), PVC compound (n. = 403) and autoclave (n. = 209) workers. As an internal reference we used two groups of workers: technicians and employees (main reference: n. = 202 subjects), with the group of other blue collar workers (n. = 639) added for statistical purposes only (minor reference: n. = 841 subjects). RESULTS: Pooling the four subgroups of exposed workers, the comparison with the main reference group allowed us to detect increased mortality from all causes of death (RR = 2.09; CI = 1.09-4.00; 160 deaths), all tumours (RR = 1.53; ns; 81 deaths), lung cancer (RR = 2.05; ns; 29 deaths) and cardiovascular diseases (RR = 3.57; ns; 29 deaths). The analysis for each specific subgroup revealed increased mortality from all causes of death among both PVC baggers (RR = 2.66; CI = 1.27-5.59) and PVC compound workers (RR = 2.68; CI = 1.36-5.27). Comparison of the minor reference group with the overall population of exposed workers showed increased RRs for other diseases, namely, liver tumour (RR = 4.08; ns; 9 deaths), lymphomas and leukaemia (RR = 2.97; ns; 7 deaths) and liver cirrhosis (RR = 3.30; ns; 11 deaths). The analysis for each specific subgroup revealed significantly increased RR for all tumours among PVC compound workers (RR = 1.74; CI = 1.06-2.85), for lung cancer among PVC baggers workers (RR = 3.04; CI = 1.15-7.99) and for liver cancer (RR = 9.57; CI = 1.69-54.1) and liver cirrhosis (RR = 6.32; CI = 1.37-29.07) among autoclave workers. In addition, the two deaths from brain tumour were observed among PVC compound workers. CONCLUSIONS: To highlight the risk previously reported in the literature and to reduce the possible dilution effect (due to comparison bias, healthy worker effect), it proved methodologically pivotal to separate exposed and probably unexposed workers (considered as an internal reference group).

Adult↗
PubMed1992

Mode of inheritance of nonsyndromic cleft lip with or without cleft palate: a reanalysis.

Nonsyndromic cleft lip with or without cleft palate (CL +/- P) is traditionally recognized as a multifactorial threshold trait (MFT). Recently, however, evidence for the involvement of a major gene in the etiology of CL +/- P has been reported. To assess the potential for major-gene involvement in the etiology of this trait, familial recurrence patterns from several family studies of CL +/- P were reanalyzed. The recurrence patterns in first-degree relatives of CL +/- P probands were found to be compatible with the expectations for either an MFT or a generalized single-major-locus (gSML) trait. The use of multiple thresholds based on proband sex, defect bilaterality, or palatal involvement did not help to discriminate between these models. However, the pattern of recurrence among MZ twins and more remote relatives of CL +/- P probands is not consistent with gSML inheritance but is compatible with either an MFT model or a model specifying multiple interacting loci. For such a model, no single locus can account for more than a sixfold increase in risk to first-degree relatives. These findings have important implications with regard to the feasibility of detecting linkage to loci conferring susceptibility to CL +/- P.

Cleft Lip↗
PubMedDate not supplied

[Positive and negative schizophrenic symptoms: a reanalysis of the dichotomous model of schizophrenia].

The positive and negative symptoms were analyzed in 115 schizophrenic patients (DSM-III-R criteria) through correlative and factorial analyses, in order to test the positive-negative hypothesis of schizophrenia. The intercorrelative analysis showed high intercorrelations between negative, but low or no correlations between positive symptoms (excepting delusions with hallucinations), which implies that the group of positive symptoms may represent more than one type of symptom complex. This results were confirmed by factorial analysis which identified three distinct clusters of symptoms: the negative syndrome (affective flattening, alogia, abolition-apathy, and anhedonia-asociality), the disorganizative syndrome (positive formal thought disorder, and attentional impairment) and the positive syndrome (delusions and hallucinations). No inverse relations were observed between positive and negative syndromes. This results no support the bipolar-independence hypothesis of the positive-negative distinction in schizophrenia and they need to be confirmed through external validators.

Adult↗
PubMed1990

The importance of renal ammonia metabolism to whole body acid-base balance: a reanalysis of the pathophysiology of renal tubular acidosis.

Traditionally, the renal collecting duct has been assigned the dual role of (1) secreting protons derived from dietary metabolism to form luminal NH4+ and titratable acid and (2) generating new HCO3-. This view has recently been challenged. According to current concepts, whole body proton balance is maintained predominantly by the lungs which excrete protons derived from dietary metabolism as the acid anhydride CO2. In the process of excreting CO2, HCO3- is also lost from the body. It is the function of the kidney to generate new HCO3- to replenish this loss. The major site of new HCO3- generation is the proximal tubule rather than the collecting duct. New HCO3- is generated predominantly via the metabolism of organic anions, i.e. alpha-ketoglutarate, citrate, lactate, fatty acids. In the process of generating alpha-ketoglutarate from glutamine, NH4+ is formed. Under normal acid-base conditions, 50% of the NH4+ produced is excreted in the urine, and the remaining 50% is delivered to the renal veins. NH4+ delivered to the renal veins consumes HCO3- during ureagenesis. In the discussion which follows, these new concepts are reviewed and applied to an analysis of the pathophysiology of renal tubular acidosis.

Acid-Base Equilibrium↗
PubMed1990

Congenital malformations, stillbirths, and early mortality among the children of atomic bomb survivors: a reanalysis.

Of all the data sets pertinent to the estimation of the genetic risks to humans following exposure to ionizing radiation, potentially the most informative is that composed of the cohort of children born to atomic bomb survivors. We present here an analysis of the relationship between parental exposure history and untoward pregnancy outcomes within this cohort, using to the fullest extent possible the recently revised estimates of the doses received by their parents, the so-called DS86 doses. Available for study are 70,073 terminations, but DS86 doses have not been or presently cannot be computed on the parents of 14,770. The frequency of untoward pregnancy outcomes, defined as a pregnancy terminating in a child with a major congenital malformation, and/or stillborn, and/or dying in the first 14 days of life, increases with combined (summed) parental dose, albeit not significantly so. Under a standard linear model, when the sample of observations is restricted to those children whose parents have been assigned the newly established DS86 doses (n = 55,303), ignoring concomitant sources of variation and assuming a neutron RBE of 20, the estimated increase per sievert in the predicted frequency of untoward outcomes is 0.00354 (+/- 0.00343). After adjustment for concomitant sources of variation, the estimated increase per sievert in the proportion of such births is 0.00422 (+/- 0.00342) if the neutron RBE is assumed to be 20. A "one-hit" model with appropriate adjustments for extraneous sources of variation results in an almost identical value, namely, 0.00412 (+/- 0.00364). When the sample is extended to include parents lacking the full array of dose parameters necessary to calculate the DS86 dose, but sufficient for an empirical conversion of the previously employed T65DR dose system to its DS86 equivalent, we find under the linear model that the estimated increase per sievert in untoward pregnancy outcomes is some 31% higher than that published previously, 0.00264 (+/- 0.00277), assuming an RBE of 20, after adjustment for extraneous sources of variation. (Since a dose could not be calculated in 367 of the 70,073 outcomes, the n = 69,706). The corresponding value with the one-hit model is 0.00262 (+/- 0.00294).

Cohort Studies↗
PubMed1989

Reserve capacity of the elderly in aging sensitive tests of fluid intelligence: a reanalysis via a structural equation modelling approach.

In the last decade there has been a growing interest among developmental psychologists to investigate whether the cognitive performance of older adults can be improved by means of training programs. A number of cognitive training studies involving aging sensitive abilities of fluid intelligence have been performed with healthy older adults (Willis et al. 1981; Baltes et al., 1984/1986). In this paper we reanalyse data from Baltes et al. (1986) concerning the ADEPT Induction, ADEPT Figural Relations, Induction Standard and the Raven's Advanced Progressive Matrices Tests. In contrast to the above study, where the data analysis was based on a MANOVA approach, usually carried out when experimental data were gathered, this discussion implements an approach to change measurement for which the structural equation of different aspects of change in means as manifested in the moment matrices. The results here confirm these by Baltes et al. (1986), and suggest conclusions concerning change in means over time in the experimental and control groups, which are not implied by their study.

Aged↗
PubMed1989

A blind reanalysis of a random subset of NCI bioassay studies: agreement between rats and mice.

There are many problems in the statistical analysis of long-term rodent studies. This paper discusses the alternative approaches to these problems suggested by the previous three papers and compares the results of the different analyses on 25 rat and mouse studies. It is concluded that many problems remain unresolved and that alternative, seemingly reasonable decision rules can give rise to dramatically different results.

Animals↗
PubMed1987

Incidence of breast cancer in women: a reanalysis.

The assumption was made that the incidence of carcinoma of the breast in women was a power function of the age of the population. This produced equations that provided excellent descriptions of the 2 lines obtained (correlation coefficients of 0.98 and 0.99). The "common point" of the 2 equations of incidence versus age was 42 years of age, suggesting that events just prior to menopause may be related to the lower rate of increase of carcinoma of the breast. The dual line description also appears, based on reported mortality data, to be relevant to cancer of the ovary, cervix and corpus uteri in women.

Adult↗