Biomedical subjects

M Dubach

Publications and source records attributed to M Dubach.

21 records · Page 2Linked to original sources

PubMed1981

Quantitative analysis of the respiratory system of the house sparrow, budgerigar and violet-eared hummingbird.

In the house sparrow, the budgerigar and the violet-eared hummingbird the volumes of the lungs and air sacs are estimated from silicone casts. The quantitative composition of the lungs and of their compartments are measured on lung slices, the relative volumes of the parabronchi on histological sections, and the volume composition of the blood-air capillary network of the parabronchi on electron micrographs. On electron micrographs the exchange surface and the thickness of the air-blood diffusion barrier are also measured. From these data the morphological membrane diffusion capacity is calculated and related to several organ weights. The volume of the lungs and air sacs makes up 14-22% of the total body volume, the lungs only 2.3-2.9%. The exchange surface varies from 61 cm2/g (budgerigar) over 70 cm2/g (house sparrow) to 99 cm2/g (violet-eared hummingbird). The very thin barrier in these small birds results in a membrane diffusion capacity of 0.122 in budgerigars up to 0.271 ml O2/mm Hg . min . g in violet-eared hummingbirds. The various parameters are compared with those of corresponding mammals, and the quantitative advantages of the avian respiratory system are discussed.

Animals↗

PubMedDate not supplied

Viable adrenal medullary transplants in non-human primates: increasing the number of grafts.

The robust survival of stereotaxic adrenal medullary autografts in monkey brain parenchyma depends heavily on technique. One aspect of technique critical for clinical applications of CNS grafting is the problem of spreading treatment effects throughout large regions in a primate brain. Stereotaxic placement of a large number of grafts, which would address this problem, would require that later grafts retain the capacity for viability over a long period of time during the surgery, while earlier grafts are being made. In the present experiments involving 12 longtailed macaques (Macaca fascicularis), some grafts remained in medium 2.5 h before being transplanted, without apparent loss of viability. A clinically sufficient distribution of graft tissue would also require a large number of separate grafts to be derived from one adrenal medulla. One method for subdividing the gland might be to cut it into numerous very small pieces, but various dicing techniques described in this report have yielded little viable graft tissue. On the other hand, the number of ribbon grafts of the original dimensions available from a single gland is rather small; adrenal ribbons of the original dimensions were therefore further dissected. Half-length and half-width ribbons were successful, but less so than full-size ribbons in terms of proportionate viability. An assay of behavioral effectiveness, applied to all subjects described here, is presented in a separate contribution.

Adrenal Medulla↗

PubMedDate not supplied

Behavioral effects of adrenal medullary transplants in non-human primates.

Small multiple "ribbon" autografts of intact adrenal medulla stereotaxically implanted at several sites throughout the striatum in longtailed macaques (Macaca fascicularis) have been shown to contain large amounts of viable glandular tissue as long as eight weeks after transplantation. Variations of technique clearly influence viability. All monkeys were maintained in specially adapted rotometer cages so that 24-hour measurements of activity and directional bias could be gathered. Lesions induced by intracerebral injection of 6-hydroxydopamine in the substantia nigra produced the expected chronic decrease in percentage of contralateral turning in most of the 24 subjects. Animals that received the longest viable ribbon grafts showed a reversal of this effect back toward base line, whereas monkeys whose grafts left little or no surviving tissue showed no behavioral improvement.

Adrenal Medulla↗