The effect of acid proteinase inhibitors on chicken pepsin.

1. The activity of chicken pepsin was partially inhibited by dimethyl-(2-hydroxy-5-nitrobenzyl)sulphonium bromide, but was unaffected by p-bromophenacyl bromide. 2. In the presence of Cu2+, diazoacetylnorleucine methyl ester completely inactivated chicken pepsin with the incorporation of 1 mol/mol. The mechanism of the reaction was similar to that with pig pepsin. 3. Chicken pepsin was completely inactivated by 2-diazo-4-bromoacetophenone in the presence of Cu2+. 4. Chicken pepsin was almost completely inactivated by 1,2-epoxy-3-(p-nitrophenoxy)propane at 25 degrees C, 3-4mol of inhibitor/mol being incorporated. The reaction at 10 degrees C was investigated briefly. 5. Calf chymosin was inactivated by 1,2-epoxy-3-(p-nitrophenoxy)propane at 10 degrees C, the incorporation of 1 mol/mol being required for complete inhibition. 6. The characteristics of the reactions of chicken pepsin with the above compounds were compared with those of other acid proteinases.     

Observations on neurons and neuroglia from the area of the reticular formation in tissue culture

Summary The area of the reticular formation of the brain stem of several newborn and young manmals was cultivated in vitro. Neurons were observed for a period up to 54 days. At the end of this period in many preparations they still exhibited signs of chromatolysis as judged by the eccentric position of the nuclei and the peripheral location of the Nissl material. It has been impossible thus far to identify particular neurons as belonging to a particular nucleus of the reticular formation, probably due to slight morphological and structural changes of these cells in vitro. Although the oldest neurons observed were kept only 54 days in vitro it seems likely that they could have been maintained for a longer time since their appearance indicated more regenerative rather than degenerative features.Observations on the morphology and kinetics of glial and mesenchymal cells corroborated the findings of Pomerat and Costero (1956) and of Hild (1954, 1957a).This investigation was supported by a research grant (PHS B-364 [C4]) from the National Institute of Neurological Diseases and Blindness, of the National Institutes of Health, Public Health Service, administered by C. M. Pomerat.Fulbright and Smith-Mundt fellow.     

The effect of inhibitors on the formation of phosphoenolpyruvate by rat liver mitochondria

1. Rat liver mitochondria oxidizing malate produce PEP (phosphoenolpyruvate) without the addition of ATP or other nucleotides. 2. The addition of oligomycin in the presence of 2,4-dinitrophenol did not abolish PEP formation and in some instances stimulated its formation. 3. Formation of PEP was inhibited by arsenate. 4. Arsenite decreased PEP formation and caused accumulation of pyruvate. 5. Added GTP and ITP had no effect on PEP formation. 6. PEP formed from malate in the presence of GTP and labelled P(i) had a specific radioactivity approximately the same as the P(i) with no contribution from the phosphate of the added GTP. 7. There was no parallelism between the effects of inhibitors on PEP formation from malate and their effects on the assayed activity of PEP carboxykinase. 8. In a direct comparison it was shown that the PEP carboxykinase content of mitochondria was insufficient to account for the PEP formation from malate. 9. Consideration of the kinetic characteristics of PEP carboxykinase and mitochondrial content of oxaloacetate and GTP show that this enzyme cannot account for the PEP formed from malate by mitochondria.     

The effect of a bacterial extract on synovial cells in tissue culture.

The studies reported here were undertaken to determine if Erysipelothrix crude extract (CE) could elicit consistent, detectable alterations in synovial cells in vitro. Synovial cells of rabbits were cultured in vitro and data about normal synovial cells in vitro were presented. Such cells were consistently and characteristically affected by exposure to small amounts of CE; an effect that was neutralized in the presence of specific and anti-CE anti-serum.With an increase in the amount of CE added to the cells in culture, a decreasing number of cells was formed but protein content remained relatively constant.     

Studies on the recognition of xenogeneic cells by nonimmune macrophages. I. Destruction of chicken fibroblasts in vitro by murine macrophages.

Human cord blood lymphocytes were compared with adult lymphocytes with regard to proportions of cells with surface markers for surface immunoglobulin (Ig), receptors for C′3 and the Fc-portion of IgG, as well as two types of erythrocyte rosettes (rapid and late E-rosettes). A significant decrease (P < 0.02 ? 0.05) in both early and late E-rosettes was noted when cord cells were compared to adult lymphocytes. After 20 hr of incubation at 37 °C, proportions of cells bearing Fc receptors in cord blood samples showed striking increments (P < 0.001) when compared with adult lymphocytes. T cell enrichment studies and sequential depletion of cells bearing Fc receptors as well as E-rosette forming cells indicated that the precursors of cells generating Fc receptors in vitro did not arise from cells with Fc receptors or T cell markers.