Electrical Properties of the Membranes of the Pleuropneumonia-Like Organism A 5969

The electrical properties of the pleuropneumonia-like organism A 5969 have been determined over the frequency range from 0.5 to 250 Mcps. The frequency dependence of the dielectric constant and conductivity of PPLO suspensions is completely consistent with the existence of a membrane. The PPLO has an internal conductance which in part reflects its ionic equilibrium with normal nutrient and macromolecular constituents. But it is fairly independent from variation in external ionic strength.     

THE DEGENERATIVE CHANGES IN PANCREATIC ACINAR CELLS CAUSED BY DL-ETHIONINE

Degeneration of pancreatic acinar cells in rats injected with ethionine was studied by electron microscopy. The most conspicuous morphologic lesions occurred in the ergastoplasm. There was a widening of the endoplasmic reticulum, a decrease in number of membrane-associated ribosomes, and a development of fine and coarse vacuoles containing agranular disoriented membranes. Cytoplasmic ribosomes unassociated with membranes were less numerous. Nuclear changes consisted of a coarsening and clumping of the nuclear chromatin, chromatin margination, and increased osmiophilia and vacuolation of the nucleolus. Eight to ten days after the beginning of ethionine injections, changes in zymogen granules, mitochondria, and the Golgi apparatus appeared, but only after extensive damage to the acinar cell. The effects were consistent with ethionine's known interference with protein metabolism but also suggest disturbance in ribonucleic acid metabolism. The ergastoplasmic changes after ethionine were similar in some respects to the early lesions produced in liver parenchymal cells by fasting, to the changes occurring in animals on protein-free diets, or to some of the liver changes produced by azo dye carcinogens. The ribosomal and ergastoplasmic changes represent early morphologic expressions of the biochemical effect of ethionine.     

EPITHELIAL CELL PENETRATION AS AN ESSENTIAL STEP IN THE PATHOGENESIS OF BACILLARY DYSENTERY.

LaBrec, Eugene H., Herman Schneider, Thomas J. Magnani, and Samuel B. Formal. Epithelial cell penetration as an essential step in the pathogenesis of bacillary dysentery. J. Bacteriol. 88:1503-1518. 1964.-A parent strain of Shigella flexneri 2a and a colonial mutant derived from it were studied in three animal models. Both strains were equally virulent for mice when living cells suspended in hog gastric mucin were injected by the intraperitoneal route. Feeding the parent strain to starved guinea pigs, followed by the intraperitoneal injection of opium, resulted in the formation of ulcerative lesions in the intestinal tract and in the death of these animals. When the colonial variant was fed to similarly prepared animals, the animals survived and the intestinal tract remained normal. The parent produced diarrheal symptoms and intestinal lesions after its oral administration to rhesus monkeys; the variant caused neither symptoms nor pathology in this species. Studies were carried out to define the characteristics present in the parent strain and absent in the colonial mutant, which would enable the parent to produce ulcerative lesions of the bowel and death in the guinea pig model or intestinal lesions and diarrheal symptoms in the monkey. Neither serological studies nor growth studies conducted both in vitro and in vivo offered a clue to explain this difference. The virulent parent strain was shown to penetrate the bowel epithelium and enter the lamina propria; the avirulent mutant did not do this. Entrance to the lamina propria was by way of the epithelial cell of the mucosa. The avirulent mutant did not possess the capacity to penetrate this cell. This observation was extended to show that the virulent parent possesses the ability to infect and multiply within HeLa cells; furthermore, the organisms are able to penetrate epithelial cells of the guinea pig cornea, causing ulcerative lesions. The avirulent variant possesses neither of these capacities. It is suggested that epithelial cell penetration is a major factor in determining the pathogenicity of dysentery bacilli.     

An Electron Microscope Study of the Salamander Thyroid during Hormonal Stimulation

Cytological changes in thyroid glands following administration of thyroid-stimulating hormone (TSH), were studied in adult salamanders, Ambystoma tigrinum, Triturus torosus, and Triturus viridescens by electron and light microscopy. Thyroids from untreated salamanders contained large follicles, faintly basophilic colloid, low follicle cells with flattened nuclei, and scant, slightly basophilic cytoplasm. After TSH administration the cell height and nuclear volume increased. Cytoplasmic basophilia was markedly increased and follicle lumina were reduced. In electron micrographs, stacks of ergastoplasmic lamellae appeared near the nucleus occasionally in contact with the nuclear membrane. In more advanced stages of stimulation, lamellar arrays were largely replaced by small disoriented vesicles and larger vacuoles containing colloid-like material. Sections of obliquely oriented ergastoplasmic membranes contained rows of extremely fine particles. Microvilli increased in size and number and Golgi structures became more extensive. Homogeneous osmiophilic droplets increased in size and abundance. Some of the smaller droplets were seen associated with the Golgi zone. Droplets similar in size and density frequently contained closely packed, whorled lamellae. Mitochondria showed no structural changes but occurred in aggregates interposed between the nucleus and highly folded portions of the basal cell membrane.     

Ein Beitrag zur Bekämpfung der Fritfliege in der Roggenzüchtung

Ohne ZusammenfassungMit 2 Abbildungen     

IDIOPATHIC PULMONARY HEMOSIDEROSIS

Idiopathic pulmonary hemosiderosis is a rare condition manifested by recurrent pulmonary hemorrhage of unknown cause, diffuse radiologic abnormalities, cough, hemoptysis and moderate to severe hypochromic anemia. Diagnosis can be confirmed by iron stains of the sputum or lung aspiration or by biopsy. Prolonged spontaneous remission may occur without the use of corticosteroid therapy. Studies here reported indicated that the anemia is hypochromic and microcytic anemia of blood loss and iron deficiency, in spite of the presence of large amounts of iron in the pulmonary tissue. Correction of the anemia by intensive iron therapy and transfusion is considered an important part of therapy.