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Biomedical subjects

W G Johnson

Publications and source records attributed to W G Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1991

Genetic susceptibility to Parkinson's disease.

Genetic factors clearly cause Lewy-body Parkinson's disease (PD) in a subset of autosomal-dominant families. However, most cases of PD are sporadic. The two most likely models of four discussed for sporadic PD are the reduced penetrance model and the multifactorial model. Sporadic PD is likely to be caused by the combined effect of environmental precipitating factors and genetic susceptibility factors. Because the number of major genetic factors is likely to be small, these hypotheses can be tested and genetic factors located using linkage mapping techniques. The affected pair analysis methods are especially suited to PD. Finding the genetic susceptibility factors for PD is important because this may be the fastest way to identify the environmental precipitating factors and because it may lead to prevention of PD. Because of the usefulness of identifying genetic susceptibility factors for PD, we are carrying out linkage studies in a group of 16 large autosomal-dominant families with PD and more than 300 living affected PD pairs.

Diseases in Twins↗
PubMed1991

Genetic susceptibility to Parkinson's disease.

Genetic factors clearly cause Lewy-body Parkinson's disease (PD) in a subset of autosomal-dominant families. However, most cases of PD are sporadic. The two most likely models of four discussed for sporadic PD are the reduced penetrance model and the multifactorial model. Sporadic PD is likely to be caused by the combined effect of environmental precipitating factors and genetic susceptibility factors. Because the number of major genetic factors is likely to be small, these hypotheses can be tested and genetic factors located using linkage mapping techniques. The affected pair analysis methods are especially suited to PD. Finding the genetic susceptibility factors for PD is important because this may be the fastest way to identify the environmental precipitating factors and because it may lead to prevention of PD. Because of the usefulness of identifying genetic susceptibility factors for PD, we are carrying out linkage studies in a group of 16 large autosomal-dominant families with PD and more than 300 living affected PD pairs.

Diseases in Twins↗
PubMed1990

Twin studies and the genetics of Parkinson's disease--a reappraisal.

Parkinson's disease (PD) has long been regarded as having a hereditary component. However, three recent twin studies have been interpreted as excluding any significant genetic component in the etiology of PD. In this article, we reexamine these twin studies and argue that such a conclusion is premature. We review statistical tests of twin concordance rates, including calculation of G, the coefficient of genetic determination. When variation in a trait is due entirely to genetic factors G = 1, and when variation in a trait is due entirely to nongenetic factors G = 0. We conclude that: (a) low monozygotic concordance rates can be compatible with substantial genetic contribution to etiology; (b) the PD twin study data give substantial optimal values of G (up to 0.78) but the very broad 95% confidence limits for G make it impossible for the twin study data to prove or disprove a substantial genetic component to the etiology of PD; and (c) changing clinical concepts of PD have undermined the assumptions underlying the methodology of the PD twin studies. We review three genetic models that are biologically plausible for PD and are compatible with the low twin concordance rates. Finally, we suggest that further family studies, including linkage studies, are needed to resolve this question.

Diseases in Twins↗
PubMed1990

Prevalence of bulimia among patients in a chemical dependency treatment program.

The present study sought to determine the prevalence of bulimia in a chemically dependent population and to examine the patterns of psychopathology and eating attitudes among chemically dependent patients. Seventy-six male and 62 female consecutive admissions to an impatient treatment facility for chemical dependency were administered the BULIT. Restraint Scale, MMPI and the Marlowe-Crowne Social Desirability Scale. There was no evidence for an increased prevalence of bulimia in this sample. Five of the women (8%) achieved a cutoff score on the BULIT indicative of bulimia. The similarity between mean MMPI profiles of female patients in this sample and those previously obtained for bulimic patients was greater than the similarity between MMPI profiles for the male and female chemically dependent patients in this sample. Findings are discussed within the context of previous research.

Adult↗
PubMed1990

Dietary restraint and eating behavior in the natural environment.

The influence of caloric labeling on meal selection with subjects differing in dietary restraint was investigated in a cafeteria restaurant. The three lowest calorie food selections within three food categories (i.e., salads, vegetables, entrees) were identified by labels. Within a multiple-baseline design, each food category was labeled for three evenings in a randomly determined order. Three hundred thirty-six male and female customers completed the Restraint Scale and were categorized as overweight or normal weight. Females and customers with high restraint scores chose and estimated that they chose lower calorie foods with neither effect for labeling nor a labeling-by-restraint interaction evident. Customers high in restraint also underestimated the caloric values of their selections.

Adult↗
PubMed1988

Kearns-Sayre syndrome in twins: lethal dominant mutation or acquired disease?

We studied twin brothers who met all diagnostic criteria for the Kearns-Sayre syndrome (KSS). The twins reinforce the view that KSS is a specific syndrome. They raise the possibility that the condition is inherited as a lethal dominant trait, a mode of inheritance that explains the observed paucity of familial cases. However, these cases do not exclude the possibility of an acquired cause, such as persistent viral infection of the brain.

Adult↗
PubMed1987

Familial achalasia associated with adrenocortical insufficiency, alacrima, and neurological abnormalities.

We report on two brothers with achalasia, adrenocortical insufficiency, alacrima, short stature, microcephaly, ataxia, optic atrophy, and developmental delay. The parents and three sibs are unaffected. Achalasia, adrenocortical insufficiency, and alacrima comprise a recently characterized familial multisystem disorder of unknown cause. Achalasia has also been described in association with microcephaly and mental retardation in one family and ataxia, optic atrophy, and mental retardation in another. The above reports and these sibs may represent variants of a single pleiotropic recessive gene. We suggest that abnormalities of the central nervous system are a manifestation of the achalasia, adrenocortical insufficiency, alacrima syndrome.

Abnormalities, Multiple↗
PubMed1987

Behavioral assessment and treatment of postprandial regurgitation.

The behavioral assessment and treatment of five patients with postprandial symptoms of regurgitation and "rumination" illustrate the contribution of behavior therapy to alleviating postprandial distress. They also suggest that psychological/behavioral factors may influence the development and course of some gastrointestinal disorders.

Adolescent↗
PubMed1986

N-acetyl-beta-hexosaminidase beta locus defect and juvenile motor neuron disease: a case study.

A patient with partial deficiency of N-acetyl-beta-hexosaminidase (Hex) developed a progressive motor neuron syndrome beginning at age 7, characterized by dysarthria, muscle wasting, fasciculations, and pyramidal tract dysfunction. Minor clinical features have included tremor and late distal sensory abnormalities. Rectal biopsy at age 24 demonstrated membranous cytoplasmic bodies in submucosal ganglion cells. Biochemical evaluation revealed nearly absent Hex B activity in serum, leukocytes, and fibroblasts, with partial Hex A activity in serum and leukocytes, and low normal Hex A activity in fibroblasts. Motor neuron disease can be a presentation of a Hex beta locus defect, in addition to the previously recognized Hex alpha locus defects.

Adult↗
PubMed1986

Variation in alpha-L-fucosidase properties among 28 inbred mouse strains: six strains have high enzyme activity and heat-stabile enzyme with a variant pH-activity curve; twenty-two strains have low activity and heat-labile enzyme.

Alpha-L-fucosidase in tissues of 28 inbred mouse strains varied with respect to three properties: high or low heat stability, a pH-activity curve with high or low relative activity at pH 2.8, and high or low activity. Alpha-L-fucosidase from six strains (A/J, BDP/J, LP/J, P/J, SEA/GNJ, and 129/J) had high heat stability, high pH 2.8 relative activity, and high activity, whereas the other 22 strains all had low heat stability, low pH 2.8 relative activity, and low activity. The heat-stability difference was seen in all organs tested (brain, liver, kidney, spleen, heart, skeletal muscle, lung, and testis) for two heat-stabile strains (P/J and 129/J) and four heat-labile strains (C57BL/6J, C3H/HeJ, DBA/2J, and BALB/cJ) studied in detail. The findings suggested that two structural variants of alpha-L-fucosidase, probably genetically determined, exist in these 28 inbred mouse strains, although the presence of linkage disequilibrium between alleles of tightly linked structural and regulatory genes could not be excluded.

Animals↗
PubMed1986

Variation in ten lysosomal hydrolase enzyme activities in inbred mouse strains.

Activities of 10 lysosomal hydrolase enzymes (beta-hexosaminidase, beta-galactosidase, alpha-galactosidase, alpha-mannosidase, beta-mannosidase, alpha-L-fucosidase, beta-glucuronidase, alpha-glucosidase, alpha-N-acetylgalactosaminidase, and acid phosphatase) were determined in eight organs (brain, liver, kidney, spleen, heart, skeletal muscle, lung, and testis) in males and females of six inbred mouse strains (C57BL/6J, C3H/HeJ, DBA/2J, BALB/cJ, P/J, and 129/J). Examples of enzyme-specific variation, organ-specific variation, and enzyme- and organ-specific variation were found. New enzyme-specific variants with the features of systemic regulators for alpha-L-fucosidase and beta-mannosidase were found. Known variants were detected. Organ-specific variants had some of the properties expected for a new class of genes affecting multiple enzymes: organ-specific regulators.

Acid Phosphatase↗
PubMed1986

Restraint among bulimic women.

In the present investigation, the scores of bulimic women on the Restraint, Social Desirability, and Lie scales were compared with the scores of obese dieters, obese nondieters, and nondieters whose weights were within normal limits. Bulimics attained significantly higher restraint scores than obese nondieters and normals. These results are discussed within the context of models of bulimia nervosa.

Adolescent↗
PubMed1985

Eating disorders: assessment and treatment.

Anorexia and bulimia are eating disorders affecting a significant number of adolescent and young adult women. The core symptoms of both disorders are similar and include a fear of obesity, body image disturbance, erratic eating patterns, and purging. These symptoms produce significant physical and psychologic complications. Both anorexia and bulimia appear to have a common origin in a fear of obesity and dieting. Anorectics, being "successful" dieters, lose a significant amount of weight; whereas bulimics alternate between binges and purges. Treatment for the eating disorders is gradually evolving as clinical research experience accumulates. For anorexia, hospitalization is indicated when weight falls below 15% of ideal, and most investigators agree that therapy for the core symptoms cannot be undertaken until weight is restored. During the impatient stay, a behavior modification program can effectively organize medical, nutritional, and psychologic support, and offers the quickest and most direct route to weight restoration. The nasogastric tube and total parenteral nutrition are used primarily for those who are severely emaciated or who actively resist standard modes of therapy. Inpatient treatment is most effectively and efficiently rendered in a specialized eating disorder unit. Once weight restoration is progressing, behavior therapy for core symptoms is commenced and continued on an outpatient basis. A variety of behavioral techniques are employed, and they are designed primarily to influence anorectic assumptions and beliefs. Although there may be a brief inpatient stay for initiation of treatment, the bulk of therapy for bulimia occurs on an outpatient basis. The available literature indicates that behavioral techniques and antidepressant medication are effective for the symptoms of bulimia. Early identification of core symptoms of both disorders can lead to an initiation of treatment before the core symptoms become ingrained. A potentially more effective intervention lies in efforts to influence the media. As noted, standards for feminine beauty as portrayed in the media have changed significantly over the past 20 years. An attempt at the primary prevention of eating disorders would include efforts to convince the media to change their standards of femininity from cosmetic slimness to a focus on health and physical fitness. These efforts could stem from professional and lay organizations who have the interest and capability to influence policy.

Adolescent↗