Isolated myofibers from rat skeletal muscle in suspension: cellular morphology and calcium homeostasis.

Myofiber suspensions with 80% viability (morphological intactness) were prepared from rat m. flexor digitorum brevis by a 6-hour collagenase treatment. The viable fibers had intact sarcolemmas and generally showed continuous basal laminae.

Differentiation of keratinocytes in vitro: a new culture vessel mimicking the in vivo situation.

A culture vessel consisting of two independent chambers separated only by the growth substrate is described. Cells may be cultured on both sides of the growth substrate. Culture medium and gas exposure can independently be controlled in both compartments.

The different intracellular action potentials of fast and slow muscle fibres.

The time course of the intracellular action potential was studied quantitatively, because it is an important factor in the generation of electromyographic signals. In in vivo preparations of the m. EDL and m.

Postnatal growth and differentiation in three hindlimb muscles of the rat. Characterization with biochemical and enzyme-histochemical methods.

The postnatal development, between 0 and 90 days, of three hindlimb muscles and diaphragm of the rat was investigated with respect to fiber types and diameter (histochemistry) and substrate oxidation rates and enzyme activities (biochemistry). The process of muscle fiber differentiation into mature patterns was evaluated by visual classification into 3 or 4 groups having different staining intensities for 3 enzyme-histochemical reactions, enabling 26 fiber types to be distinguished. These exhibited specific sizes and growth rates that varied among the muscles.

The use of liposomes in the topical application of steroids.

The effect of topical application of the androgen 5 alpha-dihydrotestosterone (DHT), both encapsulated in liposomes and solved in acetone, has been evaluated using the female hamster flank organ as a model system. Systemic absorption of DHT was significant from the acetone solution, but negligible from the liposome system. The topical biological effect is, however, proportionally diminished when the liposome system is used.

Differentiation of human scalp hair follicle keratinocytes in culture.

The morphology of human scalp hair follicle keratinocytes, cultured on the bovine eye lens capsule, is studied by light and electron microscopy. The hair follicle keratinocytes in the stratified cultures are characterized by the presence of numerous tonofilaments, desmosomes and lysosomes and by the presence of glycogen accumulations. The cells in the upper layers develop a cornified envelope.

Skeletal muscle fibers in suspension: a new approach to the study of oxidative and glycolytic metabolism in differentiated muscle.

A preparation of suspended fibers from m. flexor digitorum brevis of the rat was characterized with respect to morphological features, and its relevance for the study of muscular metabolism investigated. The activities of oxidative (palmitate and pyruvate oxidation) and glycolytic (lactate formation) pathways were enhanced in myofiber suspensions when compared to intact whole muscle.

Histochemical observations on the exoerythrocytic malaria parasite Plasmodium berghei in rat liver.

Enzyme histochemical methods were performed on sporozoite infected liver tissue of rats in order to gain insight into the nutrition and metabolism of exoerythrocytic forms of Plasmodium berghei. The following enzymes were demonstrated in the hepatocytic stages of the parasites, obtained 41 and 48 h after inoculation of sporozoites: acid phosphatase, cytochrome oxidase, NADH-tetrazolium reductase, succinate dehydrogenase, NAD+ and NADP+ dependent isocitrate dehydrogenase, NADP+-dependent malate dehydrogenase, lactate dehydrogenases, 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenases and alpha-glycerol-phosphate dehydrogenase. The results suggest that a conventional Embden-Meyerhoff pathway, pentose phosphate pathway and Krebs' citric acid cycle may in part be present in these exoerythrocytic parasites.

Postnatal growth and differentiation of muscle fibres in the mouse. II. A histochemical and morphometrical investigation of dystrophic muscle.

Postnatal development of three hind legs muscles, the soleus, plantaris, and gastrocnemius, of dystrophic mice (ReJ 129) was investigated with histochemical and morphometric methods. The results were compared with normal postnatal development. Especially during the second week postnatally, there was severe fibre necrosis with no apparent preference for any particular fibre type.

Postnatal growth and differentiation of muscle fibres in the mouse. I. A histochemical and morphometrical investigation of normal muscle.

A histochemical classification of muscle fibres based on three enzymes (ATPase, pre-inc. pH 4:35; succinic dehydrogenase and alpha-glycerol-phosphate-dehydrogenase) was used to describe postnatal growth and differentiation of muscle fibres. The m.

Inhibition of the expression of pathology in dystrophic mouse leg muscles by immobilization.

Normal and dystrophic calf muscles of young mice of the Bar Harbor strain Re 129 were immobilized with the foot in an extended position. Two weeks after treatment the muscles were examined morphologically. Immobilization resulted in the inhibition of fibre necrosis and, consequently, of regeneration.

An improved technique for the demonstration of glycogen depleted skeletal muscle fibres.

Glycogen depleted skeletal muscle fibres can be distinguished from non-depleted fibres with the periodic acid Schiff (PAS) reaction. In this paper the method of Meijer (1968) for the histochemical demonstration of phosphorylase activity is described as an efficient technique to increase the contrast between both groups of fibres.

Effects of irradiation on regeneration in dystrophic mouse leg muscles.

Irradiation of dystrophic mouse (strain Re 129) leg muscles with a single dose of 20 Gy 10 days after birth resulted in subtotal suppression of regeneration. One week after the treatment regenerating muscle cells were scarce, while in the contralateral untreated leg the process of regeneration was unhampered. Here, numerous young muscle cells were a striking feature.

An improved method for evaluating antiandrogens.

In recent years, the hamster flank organ test has been frequently used to screen compounds for antiandrogenic activity. When used routinely, the diameter of the pigmented spot is used to evaluate the androgenic or antiandrogenic effect of the drug tested. In this article, it is shown that the pigmented spot and the sebaceous glands may respond to a quite different degree to hormonal stimuli, indicating that visual observation alone is insufficient for screening purposes.

Observations on induced carcinosis peritonei of the Guinea pig.

A diethylnitrosamine-induced hepatocellular carcinoma cell suspension (line-10), injected intraperitoneally in Sewall Wright strain-2 guinea pigs, causes ascites with implantation of malignant cells on the peritoneal surface. At these sites, swelling of the mesothelial cells and simultaneous proliferation of underlying fibroblasts and capillaries are seen. When there are about four layers of malignant cells and the mesothelial lining is disrupted, papillary projections of fibroblasts with capillaries, covered by malignant cells develop.

Splayleg: a spontaneous limb defect in rabbits. Genetics, gross anatomy, and microscopy.

A limb defect in rabbits known as splayleg arose in a closed breeding colony of Dutch rabbits. Since the causes of this postural deformity are not fully understood, an effort was made to clarify the mode of inheritance and the etiology of the disease. Pedigree analysis and genetic mating tests showed that, in contrast to published reports, the disease is not determined by a single recessive gene with complete expressivity.

Glucose-6-phosphate dehydrogenase deficiency: biochemical and histochemical studies on hair roots for carrier detection.

Kinetic properties of human hair root glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were studied in order to optimize the assay of these enzymes in lysates from single hair roots. In contrast to previously reported methods, an excess of purified 6-phosphogluconate dehydrogenase was added to the glucose-6-phosphate dehydrogenase reaction mixtures, thus allowing a more exact quantification of glucose-6-phosphate dehydrogenase activity. Although enzyme histochemical techniques suggest a similar distribution of hair root glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, enzyme assays on hair root segments after microdissection nevertheless indicate differences in the distribution of these enzymes.