Search PubMed⌕ Search

Biomedical subjects

D Thomas

Publications and source records attributed to D Thomas.

At least 991 records · Page 55Linked to original sources
PubMed1977

Experimental evidence for a kinetic and electrochemical memory in enzyme membranes.

The existence of hysteresis phenomena in artificial enzyme membranes due to the coupling of simple kinetic enzyme properties with diffusion transport processes is reported. The intramembrane pH of a urease coating on the surface of a glass pH electrode exhibits a hysteresis loop when the pH of the bulk solution varies cyclically. The steady-state potential of a urease membrane, as a function of the substrate concentration in the bulk solution, also exhibits a memory effect. The influence of the membrane's history on its overall behavior is visualized by electron microscopy. We interpret the results in terms of a coupling between the enzyme reactions and diffusion processes, without taking into account molecular effects.

Diffusion↗
PubMed1977

The Starr-Edwards model 6000 valve. A fifteen-year follow-up of the first successful mitral prosthesis.

The Starr-Edwards model 6000 mitral valve was the first successful mitral prosthesis. A fifteen year follow-up of 110 patients undergoing isolated mitral valve replacement with this prosthesis from 1960 to 1966 is presented. There were 22 (20%) operative and 37 (42%) late deaths at a mean of 8.6 years postoperatively. Preoperative variables leading to late death and thromboembolism are analyzed. Seventeen of 25 operative survivors had improvement in their NYHA Functional Class status and eight other remained unchanged an average of 13.1 years after surgery. There are 5000 patients world-wide currently relying on this prosthesis. Despite a high rate of thromboembolism in the past, elective replacement is not recommended except in selected patients.

Aged↗
PubMed1977

Experimental pancreatic carcinogenesis. I. Morphogenesis of pancreatic adenocarcinoma in the Syrian golden hamster induced by N-nitroso-bis(2-hydroxypropyl)amine.

In serial sacrifice experiment, outbred male Syrian golden hamsters were treated once weekly for life with subcutaneous injections of N-nitroso-bis(2-hydroxypropyl) amine (DIPN). The pancreas was examined by high resolution light (1-micro sections) and transmission electron microscopy. Early nonspecific changes in all pancreatic epithelial cellular elements were followed by a progressive proliferation of intra- and interlobular duct cells, with the development of multicentric foci of cystic and papillary cystic adenomas, intraductal carcinomas, and invasive ductal neoplasms. These observations were consistent with multistage morphogenesis of pancreatic adenocarcinoma of ductal origin.

Adenocarcinoma↗
PubMed1977

[Arteriography in a case of single coronary artery with myocardial ischaemia (author's transl)].

Coronary arteriography is the only examination by which the diagnosis of single coronary artery may be made in vivo by demonstrating the presence of an entire coronary system arising from a common trunk. The discovery may be made under two distinct sets of circumstances: 1 degree Coronary ischaemia in a young subject. Arteriography confirms the diagnosis and the customary 2 degrees Coronary ischaemia in an older individual. Arteriography shows atherosclerotic lesions in a single coronary artery. The severity of the condition is related to the proximal character of the stenoses. The most logical therapeutic approach is aorto-coronary bypass if the quality of the distal network as seen at arteriography makes it possible.

Aged↗
PubMed1976

The Dirofilaria parasite in the orbit.

A 51-year-old white man had proptosis, pain, and inflammation of the left orbit and later developed diplopia. Treatment with antibiotics relieved most of the symptoms but a localized painful mass persisted in the left orbit. On biopsy a Dirofilaria worm was found. The patient was treated with corticosteroids and the residual nodule subsided. The patient was seen regularly for five months after surgery and the lesion has not recurred.

Conjunctivitis↗
PubMed1976

The preparation and testing of antihuman lymphoblast globulin for clinical use.

Antibodies to cultured human lymphoblasts were raised in horses using a schedule employing both subcutaneous and intravenous routes of injection. Plasma from groups of horses was pooled and the IgG prepared from each pool was tested extensively for safety and immunosuppressive efficacy in vitro and in vivo. On the basis of the results of skin grafting in monkeys, only globulins derived from the first main bleeds were blended to produce a bulk for clinical use. One early pool of globulin was discarded because when undiluted, it was lethal in monkeys by the intravenous route, and another pool was discarded because it contained antibodies which bound to the glomerular basement membrane of rats. No signs of toxicity as judged by haematology, blood biochemistry, and histology were detected in monkeys receiving the clinical blend of globulin either subcutaneously or intravenously.

Animals↗
PubMed1976

Observation on intranuclear crystal and nucleolar size at different stages of cell differentiation in the midgut epithelium of several insects.

Based on an inverse size relationship between nuclear crystal and nucleolus in different cells it has been postulated by several authors that the crystal develops from nucleolar materials. The purpose of the present paper is to investigate the validity of this argument. Intranuclear proteinaceous crystals appear in differentiating midgut cells of Gyrinus marinus and Tenebrio molitor. In an autoradiographic study we have previously demonstrated in these two species that the crystals do not develop from nucleolar materials. However, an inverse relationship with regard to size is observed between these 2 structures during the cell differentiation: the cross-sectional area of the nucleolus decreases when the cross-sectional area of the crystal increases. But a decrease in size of the nucleolus is also observed during the differentiation of the midgut cells of Gyrinus natator where the crystals are not present. Consequently an inverse size relationship cannot be a sufficient argument to postulate that intranuclear crystals and nucleoli are interconvertible structures; decrease in size of the nucleolus is not related to development of the intranuclear crystal.

Animals↗
PubMed1976

[Cataract due to galactokinase deficiency in a premature infant].

Report of a case of galactosemia due to galactokinase deficiency. The author recalls the clinical (opacity of the lens) and biological features (important galactosuria, gallactiloluria, normal aminoaciduria, minimal hyperglycemia following galactose load). Since symptoms of increased intracranial pressure were present in this case, as in another one previously described, the commonly accepted statement that cataract is the only lesion in galactokinase deficiency must be reconsidered.

Cataract↗
PubMed1976

Study of cytosine arabinoside (NSC-63878) synchronization plus vincristine (NSC-67574), prednisone (NSC-10023), and L-asparaginase (NSC-109229) for remission induction in advanced acute leukemia in children.

Cytosine arabinoside (CA) was utilized in efforts to synchronize leukemic cells in DNA synthesis for treatment with vincristine, prednisone, and L-asparaginase in children with acute leukemia in relapse. The results did not indicate any therapeutic advantage for patients treated with this combination compared to those treated without any attempt at CA synchronization.

Acute Disease↗