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R L Carter

Publications and source records attributed to R L Carter.

At least 37 records · Page 2Linked to original sources
PubMed1995

Height reduction among prenatally exposed atomic-bomb survivors: a longitudinal study of growth.

Using a random coefficient regression model, sex-specific longitudinal analyses of height were made on 801 (392 male and 409 female) atomic-bomb survivors exposed in utero to detect dose effects on standing height. The data set resulted from repeated measurements of standing height of adolescents (age 10-18 y). The dose effect, if any, was assumed to be linear. Gestational ages at the time of radiation exposure were divided into trimesters. Since an earlier longitudinal data analysis has demonstrated radiation effects on height, the emphasis in this paper is on the interaction between dose and gestational age at exposure and radiation effects on the age of occurrence of the adolescent growth spurt. For males, a cubic polynomial growth-curve model applied to the data was affected significantly by radiation. The dose by trimester interaction effect was not significant. The onset of adolescent growth spurt was estimated at about 13 y at 0 Gy. There was no effect of radiation on the adolescent growth spurt. For females, a quadratic polynomial growth-curve model was fitted to the data. The dose effect was significant, while the dose by trimester interaction was again not significant.

Adolescent↗
PubMed1995

Anti-Human T-lymphotropic virus type-I antibodies in atomic-bomb survivors.

Adult T-cell leukemia (ATL), induced by human T- lymphotropic virus type-I (HTLV-I), is endemic in Nagasaki, Japan. To investigate the effects of atomic-bomb radiation on development of this specific type of leukemia, 6182 individuals in the Radiation Effects Research Foundation (RERF) Adult Health Study sample in Hiroshima and Nagasaki were examined for positive rate of HTLV-I antibody. Several lymphocyte parameters were also studied for 70 antibody- positive subjects in Nagasaki. The HTLV-I antibody-positive rate was higher in Nagasaki (6.36%) than in Hiroshima (0.79%) and significantly increased with increasing age, but no association was observed with radiation dose. Whether relationship existed between antibody titer levels and radiation dose among antibody-positive subjects was not The frequency of abnormal lymphocytes tended to be higher in antibody-positive subjects than in antibody-negative subjects, and higher in females than in males regardless of radiation dose. The lymphocyte count was lower in antibody-positive subjects than in antibody-negative subjects and lower in female than in male subjects. No evidence was found to suggest that atomic-bomb radiation plays an important role in HTLV-I infection.

Adult↗
PubMed1994

Autoantibodies and immunoglobulins among atomic bomb survivors.

The purpose of this study was to determine if exposure to atomic bomb radiation affects immune responsiveness, such as the occurrence of autoantibodies and levels of immunoglobulins. Rheumatoid factor, antinuclear antibody, antithyroglobulin antibody, anti-thyroid-microsomal antibody and immunoglobulin levels (IgG, IgM, IgA and IgE) were measured among 2,061 individuals exposed to atomic bomb radiation in Hiroshima and Nagasaki whose estimated doses ranged from 0 to 5.6 Gy. The prevalence and titers of rheumatoid factor were found to be increased in the individuals exposed to higher radiation doses. The IgA level in females and the IgM level in both sexes increased as radiation dose increased, although the effects of radiation exposure were not large. No effect of radiation was found on the prevalence of antinuclear antibody, antithyroglobulin antibody and anti-thyroid-microsomal antibody or on the levels of IgG and IgE.

Adult↗
PubMed1993

Different dimerization activities of alpha and beta thyroid hormone receptor isoforms.

Thyroid hormone receptors (TR) are ligand-dependent transcription factors that are encoded as multiple isoforms on two genes. To date, no functional differences have been shown between the TR isoforms; however, the maintenance of alpha and beta genes during vertebrate evolution argues that functional differences do exist. We have localized a TR-binding site in the rabbit beta-myosin heavy chain gene. This site and TR-binding sites in the chicken lysozyme and rat alpha-glycoprotein hormone genes were used to compare the DNA-binding activities of TR alpha and TR beta and the influence of auxiliary proteins (TRAP). TR alpha formed alpha/alpha homodimers poorly, whereas TR beta formed beta/beta homodimers preferentially. This difference was not due to either a lower amount of TR alpha synthesized in the reticulocyte lysate or to an inability of the expressed TR alpha to form dimers, since both TR alpha and TR beta readily formed heterodimers with TRAP on these TR-binding sites. Additionally, a TR alpha fragment containing the dimerization domains (TR alpha C291) blocks TR beta/TRAP complexes but not TR alpha/TRAP complexes. This indicates that TR beta/TR alpha dimers form more readily than TR alpha/TR alpha dimers. We conclude that on the binding sites examined, TR beta has a greater tendency to form homodimers than TR alpha, whereas both isoforms form heterodimers similarly. The different homodimerization potentials of TR alpha and TR beta may underlie functional differences that affect thyroid hormone responses.

Animals↗
PubMed1993

The pathologist's appraisal of neck dissections.

A critical assessment is presented on the description and interpretation of histopathological findings in neck dissections undertaken in patients with squamous carcinomas originating in the head and neck. The topics covered include the localization and measurement of nodal metastases, variant histopathological appearances, micrometastases and extranodal spread.

Carcinoma, Squamous Cell↗
PubMed1993

Pathology of squamous carcinomas of the head and neck.

Recent publications dealing with the pathology of squamous carcinomas of the head and neck have been critically reviewed with particular reference to potential prognostic factors and improved methods for identifying nodal metastases. The topics covered include cytophotometry and proliferative patterns, molecular biology (EGFR and p53 genes), cell adhesion molecules (E cadherin), and combined radiologic and pathologic approaches to detect small volume metastases in cervical lymph nodes.

Carcinoma, Squamous Cell↗
PubMed1993

Histological re-evaluation of 101 intraoral salivary gland tumors by an EORTC-study group.

Tumors of the salivary glands constitute a heterogeneous group of lesions of great morphologic variation and for this reason present many difficulties in histologic classification. The histologic slides of 101 consecutive intraoral salivary gland tumors of the Department of Oral Pathology of the Free University in Amsterdam were reviewed, retrospectively, by an EORTC-study group on salivary gland tumors. Complete concurrence of diagnosis was reached in 54 cases. In 33 cases there were minor disagreements, mostly related to subclassification. Major disagreements, relating to benign versus malignant, occurred in eight cases (7.9 per cent).

Female↗
PubMed1993

Application of generalized estimating equations to a study of in vitro radiation sensitivity.

We describe an application of the generalized estimating equation (GEE) method (Liang and Zeger, 1986, Biometrika 73, 13-22) for regression analysis of correlated Poisson data from a split-plot design with a small number of experimental units. As an alternative to the use of an arbitrarily chosen working correlation matrix, we demonstrate the use of GEE with a reasonable model for the true covariance structure among repeated observations within individuals. We show that, under such a split-plot design with large clusters, the asymptotic relative efficiency of GEE with simple (independence or exchangeable) working correlation matrices is rather low. We conclude by summarizing issues and needs for further work concerning efficiency of the GEE parameter estimates in practice.

Biometry↗
PubMed1993

Monoclonal gammopathy in atomic bomb survivors.

An analysis of monoclonal gammopathy in relation to radiation exposure was conducted on atomic bomb survivors examined between October 1979 and September 1981 and between June 1985 and May 1987. There was no overall increase in the relative risk of monoclonal gammopathy and only a suggestive increase in benign monoclonal gammopathy in the second survey which did not achieve statistical significance (P = 0.17). Thirty-one cases were detected among 8796 individuals studied in the first survey, whereas 68 cases were found among 7350 people in the second survey. Among the 31 cases found in the first survey, 9 individuals (29%) died before the second survey: 4 of cancer, 4 of vascular disease, and 1 of infection. Among the 8 individuals with benign monoclonal gammopathy examined in both surveys, 4 developed suppression of residual immunoglobulin(s), suggesting the progression of monoclonal gammopathy. The overall relative risks of monoclonal gammopathy in atomic bomb survivors in the two surveys were not significantly increased with increasing radiation dose. Only benign monoclonal gammopathy in 1985-1987 showed a suggestive increase with radiation exposure. The relative risk of benign monoclonal gammopathy in 1985-1987 was 2.64 in the group exposed to 0.01-0.49 Gy and 2.14 in the > or = 0.50-Gy group (95% confidence intervals = 0.90-8.82 and 0.69-7.31, respectively).

Female↗
PubMed1992

Triiodothyronine (T3) decreases binding to DNA by T3-receptor homodimers but not receptor-auxiliary protein heterodimers.

Thyroid hormone receptors (TRs) are ligand-dependent transcription factors that bind to thyroid hormone response elements (TREs) to mediate positive and negative regulation of transcription of thyroid hormone-responsive genes. TR binding to TREs can be enhanced by interaction with a nuclear protein, triiodothyronine (T3) receptor auxiliary protein (TRAP). There are two major isoforms of thyroid hormone receptors, TR alpha-1 and TR beta-1, which are encoded on two separate genes. We studied the binding of TR alpha-1 and TR beta-1 to several TREs: the chick lysozyme TRE (F2), which is positively regulated by T3; rabbit beta-myosin heavy chain TRE, which is negatively regulated by T3; and an idealized inverted palindrome, TRElap. We demonstrate the formation of homodimers, TR alpha/TR beta dimers, and TR/TRAP heterodimers when receptor is bound to these DNA sequences. Surprisingly, we found that T3 decreased TR alpha-1 and TR beta-1 homodimer binding in a dose-dependent manner to these TREs as well as TR alpha/TR beta dimer binding to F2. In contrast, T3 did not affect TR/TRAP heterodimer binding to TREs suggesting that this heterodimer may be the stable complex occupying TREs in the presence of ligand.

Animals↗
PubMed1992

A random coefficient growth curve analysis of mental development in low-birth-weight infants.

In many medical studies, longitudinal data are collected on each of a sample of patients. The objectives of such studies often are: to estimate and test bivariate or multivariate relationships within each of several groups of patients from these repeated measures data; to compare these relationships among groups; and to test for the effects of baseline covariates on the relationships. This paper illustrates the use of statistical methods for growth curve analysis recently proposed by Vonesh and Carter for achieving these goals by relating a measure of preschool cognitive development to age in four race by sex groups of low-birth-weight infants. Significant declines in Bayley's Mental Development Index (MDI) with increasing age were found in all groups. Birth-weight did not significantly influence the rate of decline but did influence the overall level of performance. Even so, in the group most comparable to Bayley's normative population, predicted MDI was near the norm even for extremely low-birth-weight infants (that is, 1000 grams). Although there is some risk of mental deficit associated with prematurity, eventual developmental delays in low-birth-weight infants frequently are acquired with age. The rate of decline in MDI was significantly associated with race and mother's education. Assumptions required for the valid application of these methods are discussed and tested in the setting of this applied problem. The assumptions appeared valid in this application. We conclude with a brief discussion of available alternatives when the assumptions are violated and point to areas for future research.

Age Factors↗
PubMed1992

Peripheral nerve sheath differentiation in malignant soft tissue tumours: an ultrastructural and immunohistochemical study.

Thirteen soft tissue sarcomas with ultrastructural evidence of nerve sheath differentiation were investigated by immunohistochemistry. Three arose in a major nerve or nerve trunk and four patients had von Recklinghausen's neurofibromatosis. Ultrastructurally, 10 cases showed variable differentiation towards Schwann cells, two resembled perineurial cells and one tumour had features suggestive of both cell types. Immunostaining for S-100 protein was positive in eight Schwann cell tumours, negative in the other two Schwann cell tumours and negative in those with perineurial-like cells. No cases demonstrated epithelial membrane antigen, so that the existence of perineurial cells in malignant nerve sheath tumours remains immunohistochemically unsubstantiated; it may be that the perineurial-like cells are merely incompletely differentiated Schwann cells, with nerve sheath differentiation manifesting a continuous spectrum. Leu 7 was detected in four Schwann cell tumours, three of which were ultrastructurally well differentiated. Cytokeratin and desmin were demonstrated only in an undifferentiated pleomorphic area of one Schwann cell tumour. Electronmicroscopy can aid diagnosis by revealing nerve sheath differentiation in malignant soft tissue tumours without demonstrable S-100 protein.

Adolescent↗
PubMed1992

Measurement, analysis, and modelling of the caloric response. 1. A descriptive mathematical model of the caloric response over time.

A mathematical model for describing the caloric response over time offers many important advantages over the commercially-available qualitatively-fitted curves that are now used by the clinician for evaluating caloric results. In this report advances in the development of a nonlinear least-squares mathematical model are discussed and the roles and derivations of fitting parameters and curve-derived indices are outlined. This model provides a rigorous and objective description of the caloric response in its entirety with four continuous parameters. These fitting parameters make it possible to 1) describe individual caloric responses precisely and uniquely, 2) compare pairs of individual caloric responses or groups of caloric responses statistically, 3) extract information not previously available, 4) quantify variability within the caloric response, and 5) model physical properties of the caloric stimulus and physiological variables affecting the caloric response. Results from this model are compared with the results from our earlier models and with traditional multiparameter caloric results.

Caloric Tests↗
PubMed1992

Mixed-effects nonlinear regression for unbalanced repeated measures.

Repeated measures data, such as clinical pharmacokinetic data, growth data, and dose-response data, are often inherently nonlinear with respect to a given response function and are frequently incomplete and/or unbalanced. Nonlinear random-effects models together with a variety of estimation procedures have been proposed for the analysis of such data. This paper is concerned with a straightforward procedure for estimating and comparing the parameters of a generalized mixed-effects nonlinear regression model. The asymptotic properties of the proposed estimators are given and large-sample tests of hypothesis provided. The results are applied to in vitro data on the water transport kinetics of hemodialyzers used in the treatment of patients with chronic renal failure.

Biological Transport, Active↗