Search PubMed⌕ Search

Biomedical subjects

W G Johnson

Publications and source records attributed to W G Johnson.

At least 91 records · Page 5Linked to original sources
PubMed1985

Characterization of a new model of GM2-gangliosidosis (Sandhoff's disease) in Korat cats.

We have detected a disorder in Korat cats (initially imported from Thailand) that is analogous to human Sandhoff's disease. Pedigree analysis indicates that this disease in an autosomal recessive disorder in the American Korat. Postmortem studies on one affected cat showed hepatomegaly that was not reported in the only other known feline model of GM2-gangliosidosis type II. Histologic and ultra-structural evaluation revealed typical storage vacuoles. There was a marked deficiency in the activity of hexosaminidase (HEX) A and B in affected brain and liver as compared to controls. Electrophoresis of a liver extract revealed a deficiency of normal HEX A and B in the affected animals. The blocking primary enzyme immunoassay verified the presence of antigenically reactive HEX present in affected cat livers in quantities slightly elevated with respect to the normal HEX concentration in control cats. In leukocytes, obligate heterozygotes had intermediate levels of total HEX activity with a slight increase in the percent activity due to HEX A. Indeed, 4 of 11 phenotypically normal animals in addition to four obligate heterozygotes appear to be carriers using this assay. Affected brain and liver compared with control brain and liver contained a great excess of bound N-acetylneuraminic acid in the Folch upper-phase solids; thin-layer chromatography showed a marked increase in GM2-ganglioside. In summary, we have characterized the pedigree, pathology, and biochemistry of a new feline model of GM2-gangliosidosis which is similar to but different from the only other known feline model.

Animals↗
PubMed1984

Neuronal intranuclear inclusion disease in identical twins.

A pair of female identical twins exhibited slurred speech, nystagmus, and oculogyral spasms starting at age 11. The patients then had episodic rage, extrapyramidal and lower motor neuron abnormalities, and grand mal seizures, but retained largely normal intelligence, until death at age 21. Severe loss of nigral and craniospinal motor neurons was noted postmortem. Round, eosinophilic, autofluorescent inclusion bodies, 3 to 10 microns in diameter, were observed in the nuclei of most nerve cell types of the central and peripheral nervous systems and retina. Ultrastructurally the inclusions appeared as masses of filaments without a limiting membrane, the constituent filaments having a diameter of 8.5 to 9.5 nm. Histochemical results suggested the presence of proteins with a high content of tryptophan. Four similar cases have been reported previously under various designations. We propose the name neuronal intranuclear inclusion disease for the disorder.

Adult↗
PubMed1984

The influence of caloric information on cafeteria food choices.

We evaluated the effect of posting caloric information on food purchases at a cafeteria. Purchases of more than 14,300 entrees, vegetables, and salads by 6,970 customers were unobtrusively monitored via the cash register inventory control system during 15 evening observations. A quasi-multiple-baseline design across food groups was used to test the additive effect of labeling the three lowest caloric choices for vegetables, salads, and entrees. A linear logit analysis confirmed that labeling increased the probability of low calorie selections for vegetables and salads, but not for entrees. Observations of meals purchased by a subsample of 413 customers indicated labeling did not change the total caloric content of meals. The number of customers and total sales per evening were unaffected by the labeling intervention. The results suggest that manipulating environmental cues may be an effective method for changing food purchases in a cafeteria, but labeling individual items may not be the best way to decrease total calories purchased.

Journal Article↗
PubMed1983

Restrained eating: measuring an elusive construct.

As a measure of restrained eating, Herman's Restraint Scale (1978) reliably predicts laboratory food consumption in college students regardless of their weight. However, the generality and psychometric properties of the scale have not been established. In the present study, 136 male and female adults were cross-classified as obese and normal and as dieting or non-dieting. The subjects were administered a single questionnaire containing items of the Lie, Social Desirability, and Restraint scales presented in randomized order. Unlike previous reports by Herman, the three adult groups differed significantly on the Restraint Scale in the following order: Obese dieters greater than Obese non-dieters greater than normals. Also, alpha reliability coefficients varied across groups and corrected item-total correlations also displayed considerable variability with no uniformity apparent for individual item correlations. The factor analysis identified three factors within the ten item scale, and for the obese dieters, the scale was not independent of social desirability. These results indicate that the Restraint Scale has limited usefulness beyond laboratory settings with college students.

Adolescent↗
PubMed1983

Influence of external and covert food stimuli on insulin secretion in obese and normal persons.

Exposure to food produces an increase in insulin secretion that is more pronounced in obese than in normal persons. We sought to replicate this finding as well as to determine whether insulin secretion could be influenced by thoughts about food and eating. Normal and obese subjects were presented in counterbalanced order with an external food stimulus or instructions to think about food and eating. Levels of insulin, salivary output, and hunger ratings were obtained prior to and immediately following stimulus presentation. All subjects displayed higher insulin levels following stimulus presentation, with the values for the obese higher than for normals. Although the insulin secretion of the obese was greater in response to the covert as opposed to the external stimulus, the difference was not significant. Salivary output following stimulus presentation was higher for the obese than normals, with hunger ratings increasing in both groups. These data support an expanded role of insulin as an appetite-inducing mechanism.

Adult↗
PubMed1983

Prenatal diagnosis of GM1 gangliosidosis by detection of galactosyl-oligosaccharides in amniotic fluid with high-performance liquid chromatography.

Prenatal diagnosis of infantile GM1 gangliosidosis was accomplished by analyzing the galactosyl-oligosaccharides accumulating in amniotic fluid with high-performance liquid chromatography (HPLC) at 14 weeks gestation. The pattern of amniotic oligosaccharides was nearly identical with that in neonatal urine in GM1 gangliosidosis but the concentrations were about one-fiftieth of that in urine, necessitating a highly sensitive assay.

Amniotic Fluid↗
PubMed1982

Juvenile spinal muscular atrophy: a new hexosaminidase deficiency phenotype.

A 24-year-old Ashkenazi Jewish man was evaluated for a nine-year history of progressive leg weakness with fasciculations. Electromyography, nerve conduction velocities, muscle biopsy, and serum creatine kinase were consistent with anterior horn cell disease. On rectal biopsy, ganglion cells were filled with membranous cytoplasmic bodies and an unusual submucosal layer of periodic acid-Schiff positive histiocytes filled with granules was seen. Hexosaminidase A in serum and leukocytes was severely decreased in the patient and partially decreased in parents and a brother. A paternal relative had classic infantile Tay-Sachs disease. Juvenile spinal muscular atrophy in this patient, closely resembling the Kugelberg-Welander phenotype, resulted from an alpha-locus hexosaminidase deficiency disorder, possibly a genetic compound of HEX alpha 2 and a milder hexosaminidase alpha-locus allele. Other cases of hexosaminidase deficiency have included anterior horn cell disease as part of a more complex disorder, but this is the first case, to our knowledge, of a hexosaminidase deficiency disorder presenting as spinal muscular atrophy.

Adult↗
PubMed1981

The clinical spectrum of hexosaminidase deficiency diseases.

Hexosaminidase deficiency diseases or GM2-gangliosidoses were originally described as infantile encephalopathies. Recently, hexosaminidase deficiencies have been found with different phenotypes, including juvenile and adult encephalopathies, cerebellar ataxias, and motor neuron diseases. Individual cases have resembled Ramsey-Hunt syndrome, olivopontocerebellar ataxia, Friedreich ataxia, amyotrophic lateral sclerosis, Kugelberg-Welander disease, Fazio-Londe disease, and Charcot-Marie-Tooth disease. Tremor, dystonia, spastic paresis, and psychosis have been seen. Since few diagnosable causes for these system atrophies are known, these patients should be tested for hexosaminidase deficiency. These recessive disorders fit a multiple loci/multiple alleles genetic scheme, and a clinical genetic classification is presented.

Adult↗
PubMed1980

Diagnosis of adult Gaucher disease: use of a new chromogenic substrate, 2-hexadecanoylamino-4-nitrophenyl-beta-D-glucopyranoside, in cultured skin fibroblasts.

Gaucher disease is a group of lipid storage diseases in which the glycosphingolipid glucocerebroside accumulates in tissues because of deficiency of the enzyme glucocerebrosidase. Radioactively labelled glucocerebroside and the artificial fluorogenic substrate 4-methylumbelliferyl-beta-D-glucopyranoside are commonly used for its diagnosis. We studied the use of a new chromogenic substrate, 2-hexadecanoylamino-4-nitrophenyl-beta-D-glucopyranoside in cultured skin fibroblasts. The amount of reaction product, 2-hexadecanoylamino-4-nitrophenol, increased linearly with incubation time for at least 4 h and was proportional to the amount of fibroblast protein added up to 150 micrograms per incubation. The pH optimum was 4.8. The Km was 0.19 mmol/l. The mean activity of control cultured skin fibroblasts was 22.9 +/- 5.4 nmol of product formed per mg fibroblast protein per hour under standard conditions. Cultured skin fibroblasts from patients with adult non-neuropathic Gaucher disease had reduced activity, 6.4 +/- 2.4 nmol/mg/h or 28% of control activity. This compared well with mean enzyme activity in the same patients determined using the natural substrate, [14C]glucocerebroside: 28% of control activity. Heterozygotes had reduced activity with the new substrate.

Adult↗