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Biomedical subjects

J Wilson

Publications and source records attributed to J Wilson.

At least 595 records · Page 33Linked to original sources
PubMed1987

Skin cancer in black Americans: a review of 126 cases.

Primary cancer of the skin is rare in blacks. The records of 126 black patients with skin cancer were reviewed. Histopathologic findings included squamous cell carcinomas (43) basal cell carcinomas (39) malignant melanomas (8) dermatofibrosarcomas (16) Bowen's disease (6) mycosis fungoides (14) and sebaceous cell carcinoma (1).There is a higher percentage of skin cancer involving covered areas in blacks than among whites. Squamous cell carcinoma was the most common skin cancer in blacks. The distribution of basal cell carcinoma in blacks was 30 percent in this series, as compared with 80 percent in whites in the 1977 to 1978 survey. The majority of patients with squamous cell carcinoma had associated predisposing conditions and lesions on non-sun-exposed skin. Sunlight and occupational chemical exposure did not appear to be associated with skin cancer in blacks in this series.

Adult↗
PubMed1987

A maternal death due to thrombotic disease associated with anticardiolipin antibody.

We report a case of fetal death at 30 weeks' gestation followed by the unexpected death of the mother 28 1/2 hours later. At postmortem examination, extensive small-vessel thrombi were found in the maternal organs, including the uterus, kidney, and heart. In retrospect the mother had evidence of chronic pericarditis and myocarditis. Laboratory tests of antemortem serum demonstrated elevated titers of anti-double-stranded DNA and of anticardiolipin antibodies.

Adult↗
PubMed1986

Equilibrium and kinetic measurements of the conformational transition of thioredoxin in urea.

Addition of urea to solutions of Escherichia coli thioredoxin results in a cooperative unfolding of the protein centered at 6.7 M urea at 25 degrees C and 5.1 M urea at 2 degrees C and neutral pH as judged by changes in tryptophan fluorescence emission, far-ultraviolet circular dichroism, and exclusion chromatography. Kinetic profiles of changes in tryptophan fluorescence emission intensity were analyzed following either manual or stopped-flow mixing to initiate unfolding or refolding. Unfolding of the native protein occurs in a single kinetic phase whose time constant is markedly dependent on urea concentration. Refolding of the urea-denatured protein occurs in a multiplicity of kinetic phases whose time constants and fractional amplitudes are also dependent upon urea concentration. Urea gradient gel electrophoretic and exclusion chromatographic measurements suggest the transient accumulation of at least one and likely two compact nativelike intermediate conformations during refolding. Simulations of both electrophoretic and chromatographic results suggest that the intermediate conformations are generated by the concerted action of the middle and fast refolding phases.

Bacterial Proteins↗
PubMed1986

Estimation and analysis of the concentration-response surfaces associated with multiple-agent combinations.

Chinese hamster cells (V79) were treated with ethylnitrosourea (ENU) and cis-diamminedichloroplatinum(II) (DDP) alone and in combination. Sister chromatid exchanges (SCEs) were quantified as measures of genotoxicity of the two agents. The combination experiment employed a factorial design in which cells were treated, in various concentration combinations, with both agents simultaneously. Response surface methodology, using a polynomial model based on a negative binomial distribution of SCE events, was employed for analysis of the interactions of the two genotoxic agents. The negative binomial distribution, a generalization of the Poisson distribution, is required since SCEs are discrete variables which, under the conditions of these experiments, have a distribution which exhibits extra-Poisson variability. The model of the ENU/DDP combinations indicated an increasingly less-than-additive effect resulting from increasing concentrations of each agent in the combination. The analysis of these experiments demonstrates the usefulness of a powerful statistical procedure for evaluating the biological effects resulting from exposure to multiple cytotoxic agents. The methodology can be used with many other types of endpoints and is not limited by the number of treatment agents.

Cells, Cultured↗
PubMed1986

Superactivity of human phosphoribosyl pyrophosphate synthetase due to altered regulation by nucleotide inhibitors and inorganic phosphate.

Phosphoribosyl pyrophosphate (PPRibP) synthetase activity was studied in cultured fibroblasts and lymphoblasts from a male child (patient 2-A) in whom inherited purine nucleotide and uric acid overproduction are accompanied by neurological deficits. Chromatographed or partially purified preparations of the child's enzyme showed 5-6-fold increased inhibitory constants (I0.5) for the noncompetitive inhibitors GDP and 6-methylthioinosine monophosphate but normal responsiveness to the competitive inhibitors ADP and 2,3-diphosphoglycerate. Activation of the PPRibP synthetase of patient 2-A by Pi was also abnormal with 3-4-fold reduced apparent KD values for Pi. Superactivity of the PPRibP synthetase of this child thus appeared to result from a combination of regulatory defects; selective resistance to noncompetitive inhibitors and increased responsiveness to Pi activation. Selective growth of the patient's fibroblasts in medium containing 6-methylthioinosine confirmed the functional significance of the in vitro inhibitor resistance of the aberrant enzyme. Fibroblasts and lymphoblasts derived from patient 2-A showed increased concentrations and rates of generation of PPRibP as well as increased rates of the pathways of purine base salvage and purine nucleotide synthesis de novo. The magnitudes of these increases in the child's cells exceeded those in cells with catalytically superactive PPRibP synthetases. These alterations as well as the in vitro kinetic abnormalities in the patient 2-A enzyme were expressed to a reduced degree in fibroblasts from the child's affected mother, supporting the proposal that this woman is a heterozygous carrier for X-linked enzyme superactivity.

Cells, Cultured↗
PubMed1986

Effects of guanidine hydrochloride on the refolding kinetics of denatured thioredoxin.

The effect of guanidine hydrochloride concentration on the kinetics of the conformational change of Escherichia coli thioredoxin was examined by using fluorescence, absorbance, circular dichroic, and viscosity measurements. Native thioredoxin unfolds in a single kinetic phase whose time constant decreases markedly with increasing denaturant concentration in the denaturation base-line zone. This dependency merges with the time constant of the slowest refolding kinetic phase at the midpoint of the equilibrium transition in 2.5 M denaturant. The time constant of the slowest refolding phase becomes denaturant independent below 1 M denaturant in the native base-line region. The denaturant-independent slowest refolding phase has an activation energy of 16 kcal/mol and is generated in the denatured base-line zone in a denaturant-independent reaction having a time constant of 19 s at 25 degrees C. The fractional amplitude of the slowest refolding phase diminishes in the native base-line zone to a minimum value of 0.25. This decrease is accompanied by an increase in the fractional amplitudes of two faster refolding kinetic phases, an increase describing a sigmoidal transition centered at about 1.6 M denaturant. Manual multimixing measurements indicate that only the slowest refolding kinetic phase generates a product having the stability of the native protein. We suggest that the two faster refolding phases reflect the transient accumulation of folding intermediates which can contain a nonnative isomer of proline peptide 76.

Bacterial Proteins↗
PubMed1986

Facial bone augmentation using Bioglass in dogs.

In the quest for a material other than autograft and homograft bone for use in facial augmentation and replacement, materials scientists have developed numerous inert materials, some of which have a porous structure allowing scar tissue ingrowth to aid in stabilization of the implant. This study investigates a bioactive, nonporous, transparent glass (Bioglass) in a dog model for use in facial bone augmentation. In 18 dogs studied in three groups at 1, 3, and 6 months, Bioglass implants developed a bond to bone or soft tissue in 54 of 72 instances (75% of the time). Poor bonding of mobile chin implants and the loss of three implants due to infection accounted for all but three of the 18 failures. Histologic evaluation revealed no untoward tissue response. Because of the tissue bonding ability and amenability to contouring with a diamond bur at the time of surgery, Bioglass is promising as a graft material for facial bone augmentation.

Alveolar Ridge Augmentation↗
PubMed1986

Biocompatibility of silicates for medical use.

Implantation of commercial silicate glasses in soft or hard tissue will produce a thick non-adherent capsule consisting of scar tissue. However, special compositions of bioactive silicate glasses and crystallized glass-ceramics bond to bone and soft tissue without such a capsule. Bonding is via ion exchange and formation of active surface layers which incorporate collagen and bone mineral. These bioactive silicates have been studied in vivo and in vitro and the cellular response appears to depend on total cell surface nectin concentrations as well as on specific nectins and cellular proteins which may be silicon-sensitive. Simple amino acids polymerize and adhere strongly and randomly to binding sites on the bioactive surfaces, in contrast to their epitaxial behaviour on crystalline quartz. Toxicity tests in vivo and in vitro on powders and on solid forms show no adverse effects associated with bioactive silicates, in contrast with the marked toxicity of crystalline quartz. The bioactivity of the bioactive silicates may be destroyed by addition of small quantities of multivalent ions. The bioactive materials are currently in clinical use and being tested preclinically for a variety of surgical and dental applications.

Animals↗
PubMed1986

Social support, dementia and depression among the elderly living in the Hobart community.

In a community sample of the elderly (N = 274) in Hobart, Tasmania, cases of dementia and depression were ascertained by the Canberra Geriatric Mental State and the Mini Mental State Examination. Social relationships and support were examined by means of the Interview Schedule for Social Interaction. The elderly had fewer social relationships than younger adults, but were more content with what they did have. Elderly women had more affectional ties than elderly men. The presence of offspring in the same town increased the number of close ties and of social relationships, but was more important for men than for women. Persons with cognitive impairment or an established dementia reported that they had less social interaction than they would like. Depressed subjects reported having markedly less social interaction than the mentally healthy elderly, but did not complain that it was too little. This study provides a systematic description of the social environment of the elderly, both in mental health and in states of depression or impaired cognition.

Aged↗