Isolation and partial characterization of two porcine spleen ferritin fractions with different electrophoretic mobility.

Ferritin isolated from porcine spleen could routinely be separated in two fractions on nondenaturating gradient gels. Both fractions could be isolated with a purity of 96% when applied to two serially linked columns, each 200 cm in length, packed respectively with Sepharose 4B and Sepharose 6B. Both fractions were similar as judged by electron microscopy.

Effect of sarcomere length and filament lattice spacing on force development in skinned cardiac and skeletal muscle preparations from the rabbit.

Skinned cardiac and skeletal muscle freeze-dried preparations were activated in solutions strongly buffered for Ca2+. The response of single skeletal muscle fibres or thin strips of papillary muscle was investigated in relation to changes in Ca content of the perfusate. Sarcomere length was set and controlled during the experiments.

Caffeine suppresses length dependency of Ca2+ sensitivity of skinned striated muscle.

Freeze-dried skinned cardiac and skeletal muscle preparations of the rabbit were immersed in Ca2+-containing solutions with different concentrations of caffeine. The relation between the negative logarithm of the Ca2+ concentration (pCa) and normalized developed force was studied. The exact position of these Ca2+-sensitivity functions proved to be dependent on both the sarcomere length (monitored by means of laser diffraction) and caffeine concentration.

The relevance of IgA deposits in vessel walls of clinically normal skin. A prospective study.

Granular deposits of IgA are known to occur in the walls of superficial vessels in apparently healthy skin of patients with primary IgA nephropathy, Henoch-Schönlein purpura, or alcoholic liver disease, but the specificity of the finding is still a matter of debate. We investigated the disease specificity of these deposits in the skin of patients with kidney and liver diseases. The sensitivity of the finding for the diagnosis of primary IgA was 75%, the specificity was 88%.

Undergraduate medical education for primary care: a case study in New Mexico.

To address the dual problems of maldistribution of physicians and an increasing need for physicians who are lifelong learners, an experimental curricular track was developed at the University of New Mexico School of Medicine. Increased student responsibility for learning is encouraged by student-centered, small-group, problem-based tutorial learning, and early, primary care role modeling is offered during an early, lengthy, rural preceptorship. Preliminary outcomes reveal there is reinforcement of career interest in rural primary care with important linkages forged between the university and communities as a program by-product.

Electron-microscopic autoradiography of tritiated testosterone in rat testis.

The feasibility of a technique for autoradiography of diffusible substances has been further tested by analysing the localization of steroids in rat testes with the light-and electron-microscope. Testes of rats were perfused with tritiated testosterone (3 min) followed by 15-min perfusion with buffer containing a 100-fold of unlabelled testosterone. Tissue samples were frozen, freeze dried, fixed in osmium vapour and embedded in Epon.

Autoradiographic detection of mucopolysaccharide accumulation in single fibroblasts.

A method is described for localizing acid mucopolysaccharides autoradiographically in cultured cells. Normal fibroblasts and fibroblasts, from patients suffering from Mucopolysaccharidosis II disease (MPS II), were cultured for six days in the presence of 35SO4 and one day in unlabelled medium. The cultured cells were transferred to plastic film dish and, after settling, they were rapidly quenched, freeze-dried, fixed in osmium tetroxide vapour and embedded in Epon.

Dynamics of steroid uptake in rat testis studied by quantitative autoradiography.

Localization of radioactive steroids in rat testis was studied by autoradiography of tissue section. For autoradiography small tissue samples were frozen, freeze-dried under vacuum, fixed with osmium vapor and embedded in epon. The transfer of radioactive steroids was studied after in vitro perfusion of radioactive steroids in the testes isolated from hypophysectomized animals, thereby excluding the interference of endogenous steroids.

The possibility of electron microscopic autoradiography of steroids after freeze drying of unfixed testes.

A technique has been developed for the autoradiographic localization of steroids in testes at the light and possibly electron microscope level. During processing of the tissue there is no contact of tissue with water up to the moment of photographic development of the autoradiographs. Tritium labelled steroids have been introduced into the testis through perfusion of the isolated organ.