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Biomedical subjects

G Mason

Publications and source records attributed to G Mason.

103 records · Page 6Linked to original sources
PubMed1981

Role of perfusion and diffusion in 14CO2 exchange in the rabbit lung.

The rate of transfer of H14CO-3 and 14CO2 from the alveoli to the capillaries was studied in rabbit lungs perfused without erythrocytes. Aliquots of 0.5 ml of buffered solutions containing these 14C indicators and 3H2) were injected into the distal airways, and the recoveries of 14C and 3H were compared in the left atrial outflow. It was assumed that 3H2O had equilibrated between the alveoli and fluid leaving the pulmonary capillaries, and a decline in the initial 14C recovery relative to that of 3H was attributed to incomplete equilibration of 14C between these compartments. No disequilibrium of 14C could be detected at pH 7.4 when excess carbonic anhydrase was present. When the pH was increased to 8.4, 14C equilibration was only 69% complete at 36 ml/min and 41% complete at 160 ml/min. Confirmatory evidence was obtained that carbonic anhydrase is associated with the endothelial side of the alveolar-capillary barrier but is absent on the epithelial surface. The data suggest that the barrier is at least 600 times more permeable to 14CO2 than to H14CO-3, and diffusion of 14CO2 would not limit exchange at normal pH unless pulmonary flow reached extremely high values.

Acetazolamide↗
PubMed1980

Iris neovascular tufts.

Iris neovascular tufts are biomicroscopic capillary outgrowths from the pupillary margins. Iris tufts have been reported to occur in the elderly, in diabetes patients, and in myotonic dystrophy patients. Three cases have also been described in association with retinal vein occlusion. This paper describes a patient with unilateral acute retinal branch vein occlusion who had bilateral iris neovascular tufts. The bilaterality of this elderly patient's tufts suggested an underlying acquired systemic disorder. The patient denied medical illness, except for hypertension. Medical evaluation disclosed an insulin tolerance test diagnostic of diabetes, although a glucose tolerance test was not markedly abnormal. Iris tufts appeared to be associated with abnormal insulin secretion. Their occurrence with branch vein occlusion may be coincidental.

Aged↗
PubMed1979

Massive retinal gliosis simulating choroidal melanoma.

A pigmented fundus lesion in a 47-year-old woman gave a positive 32P test result and angiography showed a separate tumor circulation suggesting a diagnosis of choroidal melanoma. Examination after local resection of the tumor revealed massive retinal gliosis, a rare condition not normally considered in the differential diagnosis of choroidal melanoma. We review the clincial and histologic features that differentiate massive retinal gliosis from choroidal melanoma and astrocytic hamartoma.

Choroid Neoplasms↗
PubMed1977

Seed germination in response to diurnal fluctuations of temperature.

Diurnal fluctuations in temperature may initiate or accelerate germination in certain flowering plants, and the effectiveness of the stimulus varies according to the amplitude of fluctuation and the presence or absence of light. Attempts to assess the adaptive significance of the phenomenon, however, have been limited by the scarcity of data for species of contrasted ecology. We report here an investigation of germination responses to fluctuating temperatures, conducted on seeds of herbaceous species collected from native populations near Sheffield. The results suggest that requirements for diurnal fluctuations in temperature are characteristic of the germination of species from particular types of habitat and provide mechanisms which cause seeds to germinate at times and in places favourable for seedling establishment.

Circadian Rhythm↗
PubMed1967

Further chromatographic studies of the systematic relationship within the Anopheles gambiae complex; studies of laboratory strains.

As serious consideration is given to initiating malaria eradication programmes in tropical Africa, it becomes essential to be able to distinguish between the various species comprising the Anopheles gambiae complex. At the present time, A and B species cannot be separated by conventional taxonomic methods.The chromatographic method used in the thorough statistical study reported is capable of differentiating between species of the A. gambiae complex. Whereas 9 of the 10 strains studied could be distinguished from one another, 8 of the strains fell into three species-groups. The results indicate that by this technique it may be possible to discern subtle species relationships not yet established by conventional taxonomy.

Anopheles↗
PubMed1966

A chromatographic study of the systematic relationship within the Anopheles gambiae complex.

In the planning of malaria eradication programmes for Africa, it is necessary to be able to characterize and distinguish between various species of the Anopheles gambiae complex in order to proceed on a sound and economic basis. However, at present there are no reliable taxonomic methods for separating the sibling species which comprise Groups A and B.The study reported was undertaken to investigate the possibility of differentiating morphologically indistinguishable members of this complex on the basis of chromatographic patterns of fluorescing components obtained from extracts of adult mosquitos. The results indicate that this biochemical taxonomic method can be used to characterize and differentiate A. gambiae species that are indistinguishable by conventional taxonomy.

Animals↗
PubMedDate not supplied

A combination chemotherapy protocol (VELCAP-L) for dogs with lymphoma.

Ninety-eight dogs with lymphoma treated with a 5-drug combination chemotherapy regimen (vincristine, L-asparaginase, cyclophosphamide, doxorubicin, prednisone [VELCAP-L]) were evaluated for pretreatment characteristics predictive for response and remission duration. The complete remission rate was 69%, with a median remission duration of 55 weeks. Dogs with advanced stage of disease, constitutional signs, dogs that were older, and dogs that were dyspneic were less likely to achieve remission. Once in remission, small dogs and dogs without pretreatment thrombocytopenia were likely to have longer remission duration. Toxicoses were frequent, but rarely fatal, and no predictitive factors were found for a dog developing toxicoses. VELCAP-L is an effective treatment for dogs in stage I-III lymphoma, particularly in young, small animals.

Age Factors↗
PubMedDate not supplied

Examining the role of the practitioner-teacher in nursing.

This article examines the difficulties faced by specialist nurses when they attempt to combine practice and teaching roles. It gives a detailed analysis of the emergence of full-time practitioner-teachers in nursing, including the role of joint appointees. It is recommended that the practitioner-teacher role should be promoted, and this will necessitate research into the feasibility of such roles.

Consultants↗
PubMedDate not supplied

Non-melanotic skin cancer and solar keratoses in Victoria.

The light-exposed areas of the head and neck, forearms, and dorsum of each hand were examined in 2113 adults during a one-week study. The study was conducted in the isolated Victorian rural city of Maryborough which is situated in the northern part of the Central Highlands district. Of 2113 subjects, 49 (2.32%) had at least one skin cancer and 1202 (56.9%) had at least one solar keratosis. Histological confirmation of all skin cancers and doubtful solar keratoses was obtained. Age, skin type, and sunlight exposure were the major factors influencing the prevalence of solar keratoses and skin cancers.

Adult↗