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Biomedical subjects

T Reich

Publications and source records attributed to T Reich.

At least 109 records · Page 6Linked to original sources
PubMed1990

[An in vitro test procedure for evaluating dental restoration systems. 1. A computer-controlled mastication simulator].

This article describes the development and testing of a computer-controlled chewing simulator which is able to simulate the wear mechanisms and temperature changes that can occur in the mouth. It was further evaluated if the opposing cusps used in this chewing simulator should be metallic or if natural enamel was preferential. The results indicated that the machine fulfilled the parameters concerning chewing motion and thermal changes reported in the literature. Furthermore it was shown that natural enamel cusps must be used as the opposing dentition. The chewing simulator will form a part of an in-vitro test, which will allow the evaluation of dental restorative systems under clinically relevant conditions.

Computer Simulation↗
PubMed1989

NIMH Collaborative Program on the Psychobiology of Depression: clinical.

As part of the National Institute of Mental Health Collaborative Program of Depression study, data were collected on 2,225 first-degree relatives of 612 probands. A subset consisting of 187 families of bipolar patients was made available to participants of Genetic Analysis Workshop 5 (GAW5). A description of these data, including sample sizes, diagnoses, and a summary of published analyses, is given.

Adult↗
PubMed1989

Segregation and linkage analyses of bipolar and major depressive illnesses in multigenerational pedigrees.

Data were collected on six large multigenerational pedigrees, four ascertained through a proband with major depression and two ascertained through a proband with a bipolar form of illness. Diagnoses were made using the SADS-L structured interview and Research Diagnostic Criteria (RDC). Complex segregation analyses were conducted on the bipolar and the major depression pedigree sets using a model allowing for both major locus and polygenic inheritance; in these analyses a variety of diagnostic schemes and assumptions concerning the lifetime population prevalence were examined. Linkage analyses on standard markers were conducted using parameters for transmission of susceptibility to illness derived from the segregation analyses. Results of the segregation analyses were quite sensitive to the diagnostic and prevalence assumptions. In the pedigrees ascertained through probands with a bipolar form of illness, we were unable to discriminate between major gene and polygenic inheritance. The data were compatible with Mendelian major gene transmission of susceptibility to illness when bipolar and schizoaffective manic diagnoses were considered as affected and the lifetime population prevalence was between 0.04 and 0.06. Outside this narrow prevalence range, or when additional diagnoses, such as major depression or hypomania, were included as expressions of liability to disease, major gene transmission of susceptibility to disease could be rejected. Similarly, in the pedigrees ascertained through probands with major depression, it was not generally possible to discriminate between major gene and polygenic transmission of susceptibility to illness. For a diagnostic scheme including only major depression as a manifestation of susceptibility to illness, there was a narrow range of lifetime population prevalence values (female prevalence ranging from 0.20 to 0.25, male prevalence set to 1/2 female prevalence) which yielded results compatible with major gene transmission. Linkage analyses for all markers yielded negative or inconclusive results. In one bipolar pedigree a lod score of 1.65 was found with a marker in chromosome 1 recommending further studies of this chromosome.

Adult↗
PubMed1989

Schizophrenia and the question of genetic heterogeneity.

Despite major advances in psychiatric diagnosis during the past 20 years, boundaries of the schizophrenic syndrome remain elusive. Moreover, in pedigrees containing cases of schizophrenia there are marked between-pedigree differences with respect to prognosis, familial patterns of psychiatric illness, drug response, and especially association of affected status with a specific chromosomal locus. Such between-pedigree differences suggest the syndrome may be made up of several different diseases. Linkage of affected status to specific loci may aid in resolving genetic heterogeneity. Large multigenerational informative pedigrees may permit the separation into those that do and do not link to a genomic locus of interest. Admixture analysis of smaller informative pedigrees may permit separation of linked and unlinked pedigrees on the basis of differences in the recombination fraction. Finally, biological "markers" can be used before the genetic analysis to separate putative linked and unlinked pedigrees. The combined study of genetic linkage and clinical heterogeneity will aid in the resolution of etiological heterogeneity of schizophrenia and the delineation of meaningful diagnostic boundaries.

Genetic Linkage↗
PubMed1989

Cerebral cortical and white matter reactivity to carbon dioxide.

We measured cerebrovascular reactivity to carbon dioxide in the cerebral cortex and the subcortical white matter of 12 healthy adult volunteers (four young subjects aged 21-24, four middle-aged subjects aged 34-40, and four elderly subjects aged 62-85 years). Blood flow was computed from the concentration history of xenon-133 in the volume of interest measured with an ultrapure germanium detector array. End-tidal PaCO2 ranged from 35.4 to 42.6 mm Hg. The mean +/- SD baseline blood flows in the cerebral cortex were 60 +/- 7, 51 +/- 9, and 33 +/- 4 ml/100 cm3/min in the young, the middle-aged, and the elderly subjects, respectively; the corresponding subcortical white matter baseline blood flows were 21 +/- 1, 22 +/- 3, and 16 +/- 5 ml/100 cm3/min. Mean +/- SD cerebrovascular reactivities to carbon dioxide in the cerebral cortex were 2.03 +/- 0.58, 1.36 +/- 0.41, and 0.72 +/- 0.19 ml/100 cm3/min/mm Hg PaCO2 for the young, the middle-aged, and the elderly subjects, respectively; the corresponding reactivities in the subcortical white matter were 0.69 +/- 0.11, 0.59 +/- 0.17, and 0.36 +/- 0.41 ml/100 cm3/min/mm Hg PaCO2. Blood flow and cerebrovascular reactivity in the cerebral cortex of the young subjects were significantly higher than those for white matter and significantly higher than those in the elderly subjects (p less than 0.001). Age vs. blood flow (for the cortex) and age vs. cerebrovascular reactivity (for both cortical gray and subcortical white matter) also showed significant linear correlation (p less than 0.05). However, the age-related changes in white matter blood flow and cerebrovascular reactivity were slow, and the differences among the age groups were not statistically significant.

Adult↗
PubMed1989

The cognitive triad and suicide intent in depressed in-patients.

Daily ratings of self-esteem, hopelessness and suicide intent were made by senior psychiatric residents on 60 patients hospitalized for depression. Both hopelessness and low self-esteem correlated highly with suicide intent and both contributed independently to suicide intent. This suggested that self-esteem may be important in the development of suicide intent as well as hopelessness.

Attitude↗
PubMed1989

Quantitative margin analysis in the scanning electron microscope.

Interface between restorative materials and tooth hard substances must be morphologically as perfect as possible to avoid plaque accumulation and subsequent secondary caries or pulpal diseases. Therefore the marginal behavior of restorations is an important parameter to predict their longevity. Morphologically, the quality of margins is characterized by different well defined criteria. Using a replica technique it is possible to assess the complete marginal circumference of restorations in the SEM. Margins of restorations show a large variety of their morphology. This publication describes a method to quantify the quality of dental restorations. The restoration margins are traced on the SEM screen with a digitizer and an interface to measure the margin's length. Simultaneously the margin quality is assessed and assigned to the corresponding lengths. The % distribution of the quality criteria for each restoration is then calculated. Using a comparative light microscope, the replicas are aligned and mounted identically in the SEM for longitudinal studies. The results presented are limited to tests for the accuracy of the method. Using 5 criteria to characterize the margin quality, it was found that the difference between two measurements by the same operator, 4 weeks apart was 3% +/- 2.6%. The largest difference for one group was 9%. In another accuracy test where 4 criteria for margin characterization were used, the difference between two measurements was 1.9% +/- 0.9%. The largest difference between two groups found was 3.4%. This method can be used for longitudinal studies in vivo, but also for in vitro screening tests with new materials.

Dental Restoration, Permanent↗
PubMed1988

Familial resemblance in energy intake: contribution of genetic and environmental factors.

Total energy intake and intakes of carbohydrate, fat, and protein as well as the percentage of energy derived from these nutrients were calculated from a 3-d dietary record in 1597 subjects living in 375 families of French descent. Familial correlations were computed in pairs of biological relatives and relatives by adoption and used in the path-analysis BETA model to determine the contribution of genetic and nongenetic factors in the familial resemblance observed in energy intake. No significant genetic effect was found for intake of any nutrient tested (h2 less than or equal to 11%) and cultural inheritance was found to be more important than genetic inheritance. Nontransmitted environmental factors, including home environmental effects, were found to account for more than 50% of the variation observed in the energy-intake components. These results suggest that the average genetic influence on nutrient intake is negligible and that nongenetic effects associated mainly with home environmental effects are the major affecters of energy intake.

Adolescent↗
PubMed1988

Secular trends in the familial transmission of alcoholism.

This is a study of the familial transmission of alcoholism in the families of 60 female and 240 male alcoholics ascertained in four psychiatric hospital units and in a local parole office. Eight hundred and thirty-one interviewed first-degree relatives and 125 spouses are included. The lifetime population prevalences of alcoholism in white males and females based on the Epidemiological Catchment Area Study in St. Louis were compared with the family rates. A semistructured comprehensive interview schedule (Home Environment and Lifetime Psychiatric Evaluation Record) was used and diagnoses made according to Feighner criteria for alcoholism. The methods of Survival Analysis established the presence of strong secular trends in the age-of-onset and lifetime prevalence of alcoholism in these families and in the general population. Accordingly, new methods for the analysis of family data that incorporate secular variation were developed. The Multifactorial Model of Disease Transmission was used to estimate familial correlations and these were parameterized by the "Tau" model of Familial Transmission. The model does not assume that all familial resemblance is due to genetic factors, but also includes the possibility of nongenetic transmission. Our analyses confirmed that more recently born cohorts of individuals had increased expected lifetime prevalences of alcoholism and decreased ages of onset, when compared with older cohorts. Separate age-of-onset distributions were required for males and females and the secular trends in age-of-onset were greatest in females. The differences between males and females were least in more recently born cohorts suggesting that sex-specific differences in the family and population distribution of alcoholism are decreasing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Alcohol-related symptoms in heterogeneous families of hospitalized alcoholics.

Heterogeneity in the clinical symptoms of alcohol abuse was examined in 243 men and 305 women from families of hospitalized alcoholics, who had demonstrated different patterns of inheritance of susceptibility to alcoholism. Discriminant analysis was utilized to identify nine alcoholic symptoms that distinguished male relatives of alcoholic men from those of alcoholic women. Inability to abstain from alcohol, fighting and reckless driving while intoxicated, and alcohol treatment other than Alcoholics Anonymous were more prevalent in families of male probands. Male relatives of female probands experienced later onset of loss of control over drinking associated with benders, and cirrhosis and feelings of guilt. Female relatives of alcoholic men and women showed a marked predominance of the latter (Type 1) features, whereas male relatives had different clinical features, depending on the associated mode of inheritance.

Adult↗
PubMed1988

Genetic heterogeneity and the classification of alcoholism.

Recent progress toward a systematic pathophysiological model of alcoholism has led to identification of two distinct subtypes of alcoholism. These subtypes may be distinguished in terms of distinct alcohol-related symptoms, personality traits, ages of onset, and patterns of inheritance. Type 1 alcoholism is characterized by anxious (passive-dependent) personality traits and rapid development of tolerance and dependence on the anti-anxiety effects of alcohol. This leads to loss of control, difficulty terminating binges once they start, guilt feelings, and liver complications following socially encouraged exposure to alcohol intake. In contrast, type 2 alcoholism is characterized by antisocial personality traits and persistent seeking of alcohol for its euphoriant effects. This leads to early onset of inability to abstain entirely, as well as fighting and arrests when drinking. Empirical findings about sex differences, ages of onset, associated personality traits, and longitudinal course are described in a series of adoption and family studies in Sweden and the United States. Implications for future research and clinical practice are discussed.

Adoption↗
PubMed1987

The familial transmission of bipolar illness.

As part of the National Institute of Mental Health Collaborative Program on the Psychobiology of Depression study, data were collected on 2225 first-degree relatives of 612 probands. We analyzed 187 families of bipolar patients (149 probands with a diagnosis of bipolar I disorder and 38 with a diagnosis of schizoaffective, manic subtype). Using traditional genetic methods, the morbid risk of bipolar illness in relatives was found to be 5.7% in the relatives of bipolar probands as contrasted with 1.1% in the relatives of probands with major depression. These values compared closely with those obtained using survival analysis. Relatives of probands with early onset were found to have a greater risk than relatives of probands with late onset. The sex of the relative, the sex of the proband, or the subtype of the proband (bipolar I or schizoaffective bipolar) did not influence the risk in the relative. The age at onset was found to be accelerated with birth cohort, with individuals born in more recent cohorts having an earlier onset. Multifactorial analysis found significant heterogeneity for sex-specific sibling correlations (with the brother-sister correlation smaller than the same-sexed correlations), and path analysis estimated transmissibility of liability to be 71%. The mixed model, which allows for a single major locus with a multifactorial background, gave evidence for the presence of a major locus when controlling for the effects of birth cohort and age at onset. However, this evidence is tempered when comparing the mixed model with a more general transmission model.

Adolescent↗
PubMed1987

Familial rates of affective disorder. A report from the National Institute of Mental Health Collaborative Study.

We examined familial rates of affective disorder and related illness in a cohort of 955 probands studied at five centers in the National Institute of Mental Health Collaborative Study of the Psychobiology of Depression: Boston, Chicago, Iowa City, New York, and St. Louis. Six hundred sixteen of these probands were entered into a family study, and 3423 of their first-degree relatives were evaluated. The probands were divided into five diagnostic groups: schizoaffective-bipolar (n = 37), schizoaffective-depressed (n = 18), bipolar I (n = 151), bipolar II (n = 76), and unipolar (n = 330). The relatives of bipolar I probands had a higher rate of bipolar I illness than the relatives of unipolar probands, but the relatives of unipolar probands did not have a higher rate of unipolar illness than the relatives of bipolar I probands. The relatives of probands with schizoaffective disorder, depressed subtype, had a higher rate of schizophrenia than the relatives of schizoaffective-bipolar probands, suggesting that bipolar schizoaffective disorder may be closer to pure affective disorder while schizoaffective depression may be closer to schizophrenia. An increase in bipolar II illness was also observed in the relatives of bipolar II probands. Overall, these data support the widely accepted distinction between bipolar and unipolar affective disorders.

Adult↗
PubMed1987

Etiologic heterogeneity in alcoholism.

Etiologic heterogeneity in alcohol abuse was evaluated in 195 extended pedigrees, comprising 288 nuclear families of 140 male and 55 female Caucasian American hospitalized alcoholics. Previous adoption studies in Sweden demonstrated differential heritability of two patterns of alcohol abuse in men: type-2 alcoholism exhibited early onset of abuse associated with criminal behavior, while type-1 abuse began at a later age, uncomplicated by antisocial traits. Alcohol abuse in female Swedish adoptees was relatively homogeneous and similar to the late-onset, type-1 abuse. The notion of etiologic heterogeneity, as suggested by the Stockholm Adoption Studies, was examined in the American pedigrees by contrasting the models of familial transmission of susceptibility to alcoholism obtained via segregation analyses of families of male versus female probands. Families of male probands demonstrated significant familial resemblance, accounted for by a multifactorial-polygenic background in addition to a major (gene) effect. In contrast, familial resemblance in the pedigrees of female probands was attributed solely to a multifactorial-polygenic effect. We considered whether some families of male alcoholics were similar to families of female probands, who expressed type-1 abuse predominantly. Pedigrees of male probands were separated in two groups: (1) "female-like" families had a better likelihood for the model obtained for families of female probands than the one for families of all male probands, (2) "male-like" families had a better likelihood for the model of familial transmission describing families of all male probands. A statistically significant difference in the pattern of familial transmission was observed between the "male-like" and "female-like" groups. Discriminant function analysis of alcohol-related symptoms showed that the familial subtypes differed in clinical features as well. Alcohol abuse by male relatives in "male-like" families was characterized by the early onset of inability to abstain entirely from alcohol or lack of desire to stop drinking; in contrast, abuse in "female-like" families was characterized by late onset of guilt feelings and loss of control over binge drinking.

Adolescent↗
PubMed1987

Another look at the pentoxifylline efficacy data for intermittent claudication.

Porter et al have reported that pentoxifylline shows statistically significant superiority over placebo in a seven-center, double-blind, parallel group, randomized trial of outpatients with intermittent claudication secondary to chronic occlusive arterial disease. The objective of this report is convey results of the intention-to-treat population, paying careful attention to relevant methodologic issues relating to the analysis of clinical trials. At the same time, a new measure of clinical efficacy, minimum distance walked, is proposed. The rationale for this measure is discussed and results are compared with those for walking distances at each visit. The reanalysis of the Porter et al data by "intention to treat" and by use of the minimum-distance-walked measure confirms the published findings of efficacy of pentoxifylline for treatment of intermittent claudication.

Aged↗
PubMed1987

Age-period-cohort analysis of secular trends in onset of major depression: findings in siblings of patients with major affective disorder.

Analyses of data from the NIMH-CRB Collaborative Depression Study on age at onset of Major Depressive Disorder (MDD) in 1144 directly interviewed siblings of patients with major affective disorder show a strong secular trend toward increased lifetime risk and earlier onset in successive cohorts of birth since 1930. The proportionate increases in the instantaneous probabilities (hazard) of onset of MDD for each one year difference in year of birth were 5% for brothers and 7% for sisters. Age-period-cohort analysis suggests a powerful period effect may be responsible for this secular trend in rates of MDD, with rates of onset for siblings between 15 and 50 years of age doubling between the 1960s and 1970s. Possible artifacts are investigated.

Adolescent↗