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Biomedical subjects

W G Johnson

Publications and source records attributed to W G Johnson.

At least 109 records · Page 6Linked to original sources
PubMed1980

Metabolic interference and the + - heterozygote. a hypothetical form of simple inheritance which is neither dominant nor recessive.

Another form of simple inheritance is possible which is neither dominant nor recessive and in which the heterozygote alone is affected. In this system, homozygosity for the normal allele AA, and the mutant allele A'A', give a normal phenotype. Only the heterozygous condition AA' (+ - heterozygote) produces an abnormal phenotype because the two alleles, when present together, interact to produce a harmful effect. This metabolic interference may occur because the two allelic genes code for different subunits of a multisubunit enzyme or structural protein. The two genes may interact in other ways and need not be allelic. The various matings result in pedigrees, which in some cases resemble those of dominant or recessive inheritance, and in other cases are unique. Certain unusual pedigrees in the literature are compatible with the predictions of metabolic interference and are difficult to explain by other means. Metabolic interference is most likely to be recognized as: (1) a disorder limited to females, apparently dominant or recessive, especially a disorder passed to affected females through unaffected males; (2) a disorder occurring in all members of a large sibship with normal parents; (3) a disorder occurring in all members of a large sibship with one parent similarly affected; (4) an apparently dominant disorder with females more severely affected than males; (5) an apparently X-linked dominant disorder in which males are not more severely affected; or (6) any autosomal dominant disorder. Examples of possible metabolic interference exist among disorders of animals, and the mechanism could be a factor in speciation. Tissue culture methods could be used to demonstrate metabolic interference.

Alleles↗
PubMed1980

Alpha-locus hexosaminidase genetic compound with juvenile gangliosidosis phenotype: clinical, genetic, and biochemical studies.

A 3-year-old boy developed progressive neurological deterioration in his third year, characterized by dementia, ataxia, myoclonic jerks, and bilateral macular cherry-red spots. Hexosaminidase A (HEX A) was partially decreased in the patient's serum, leukocytes, and cultured skin fibroblasts. Hexosaminidase was studied in serum and leukocytes from family members. Four members of the paternal branch appeared to be carriers of classical infantile Tay-Sachs allele, HEX alpha 2, probably receiving the gene from one great-grandparent of Ashkenazi origin. In the maternal branch, no one was a carrier of classical infantile Tay-Sachs disease, but five individuals were carriers of a milder alpha-locus defect. The patient, therefore, was a genetic compound of two different alpha-locus hexosaminidase mutations. At least 21 families with late-infantile or juvenile GM2 gangliosidosis have been reported, 18 of them with alpha-locus mutations, and three with beta-locus mutations. Genetic compounds of hexosaminidase have been reported in at least seven families, five with alpha-locus mutations and two with beta-locus mutations. The compound had the phenotype of infantile Tay-Sachs disease in one family, infantile Sandhoff disease in another, and the normal phenotype in the rest.

Child, Preschool↗
PubMed1979

The development and evaluation of a behavioral weight-reduction program.

The development of a comprehensive weight-reduction program and its implementation in the clinic are described. The program consisted of explicit instructions on food monitoring, stimulus control, chaining, exercise, and self-reinforcement. The results of pilot research indicated that the program produced reliable weight loss and that its implementation in a group format was more positive. A formal experiment evaluated the effectiveness of program components in a 2 x 2 factorial design after ten weeks of treatment and at three-month and one-year follow-ups. There was significant weight loss with no main or interaction effects. At follow-up, those exposed to exercise and/or contingency management better maintained their weight loss or continued to lose. Data on the implementation of the program in a clinical setting are presented and these results compare favorably with reports from other clinics using behavior modification. It is suggested that our more positive results may be related to an emphasis on activity and life-style change in addition to changing eating behavior.

Adolescent↗
PubMed1978

Inheritance of the enzyme defect in a new hexosaminidase deficiency disease.

A new form of hexosaminidase deficiency disease is characterized clinically by mild, juvenile-onset, very slowly progressive cerebellar ataxia with macular cherry-red spots and absence of other findings. Biochemically there is striking hexosaminidase deficiency in serum, leukocytes, and fibroblasts. Hexosaminidase B appears absent, but hexosaminidase A-like and S-like activity is present on starch-gel electrophoresis. We studied hexosaminidase in leukocytes and serum from members of an affected patient's family and traced the enzyme defect through four generations. Leukocyte heat-stabile hexosaminidase in obligate and presumptive carriers was depressed both in specific activity (nanomoles per milligram of protein per hour) and as a percentage of total hexosaminidase. The carrier state was expressed in serum, but overlap with controls made this test unreliable. The similarity of these carriers to carriers of Sandhoff disease suggests that the disorders may be closely related, perhaps as allelic mutations of the hexosaminidase beta subunit. Those involve with screening for Tay-Sachs disease should be aware that persons with an increased percentage of hexosaminidase A--that is, a decreased heat-stabile fraction--may be carriers of hexosaminidase deficiency diseases.

Chemical Phenomena↗
PubMed1977

A new juvenile hexosaminidase deficiency disease presenting as cerebellar ataxia. Clinical and biochemical studies.

A boy with mild hand tremor since age 2 1/2 was found at 4 to have cherry-red spots and mild trucal ataxia without seizures or dementia. Biochemically, he had striking hexosaminidase deficiency (serum: 4.6 percent of normal, 88.9 percent heat-labile; leukocyte: 2.2 percent of normal, 84.6 percent heat-labile; fibroblast 12.8 percent normal, 93.1 percent heat-labile). The residual hexosaminidase activity migrated electrophoretically in two bands. The major band comigrated with hexosaminidase A, the minor with hexosaminidase S. Hexosaminidase B was totally absent. The parents had partially reduced hexosaminidase with a decreased heat-stabile fraction. This disorder may result from a new mutation closely related to that causing Sandhoff-Jatzkewitz disease.

Cerebellar Ataxia↗
PubMed1977

Treatment of vascular hemiballism and hemichorea.

Hemichorea and hemiballism have been considered debilitating and irreversible disorders. Eight patients with vascular hemichorea were treated with perphenazine. All were elderly and hypertensive. Three had primarily choreic movements while five had, in addition, proximal flailing movements of hemiballism. In seven, dramatic response to perphenazine therapy was seen, with virtual cessation of movements. In one case, only partial response was obtained with a high dose of perphenazine, and this dose had to be reduced because of drowsiness and hepatotoxicity. In four patients, movement did not recur after the drug was stopped. This study indicates that perphenazine can be a highly effective agent for the treatment of hemichorea and hemiballism and that improvement can be maintained in some patients even after therapy is discontinued.

Cerebrovascular Disorders↗
PubMed1976

Biofeedback therapy for migraine headaches.

We studied the biofeedback treatment of migraine headaches, attempting to control for some of the methodological limitations of previous work. Seven individuals suffering from migraine headache were trained in the usual finger warming procedure with the omission of autogenic phrases. Additionally, to control for placebo-expectance effects, three of these subjects received training in finger cooling prior to warming. With training in finger warming, headache activity was substantially reduced. In contrast, headache activity either remained at base line levels or increased during training in cooling despite positive therapeutic expectations. The results of this study indicate that finger temperature warming, without autogenic training, is effective in reducing migraine activity, independent of suggestion effects.

Adult↗
PubMed1975

Thorium induced hepatic hemangioendothelioma. Roentgen-angiographic findings in two additional cases with clinical "inform and consent" problems.

1. Two additional cases of presumed, thorium-induced hemangioendothelioma of the liver are reported. 2. The angiographic pattern of large venous lakes conforms closely to the pathologic descriitions of this malignancy. 3. To our knowledge, angiography of the thorotrast (and vinyl chloride) liver, before the clinical evolution of malignancy, has not been recorded and may provide information of prognostic and therapeutic value. 4. Incidental identification of thorium deposits in the tissues of clinically healthy patients creates perplexing "inform and consent" problems. Presumably, these must be solved on an individual basis. 5. Because the use of thorotrast has been discontinued since the early 1950s, all physicians reviewing chest and abdominal roentgenograms should be aware of the characteristic appearance of human thorotrast deposits, especially in the liver, spleen and celiac lymph nodes. 6. The number of living thorotrast "carriers" and previous deaths from thorotrast related malignancy seems highly uncertain at this time.

Autopsy↗