Prevention of experimental amnesia by peripherally administered cholecystokinin octapeptide in the rat

The effect of subcutaneously injected cholecystokinin octapeptide (CCK-8) on amnesia induced by electroconvulsive shock (ECS), CO₂ inhalation, or cycloheximide injection was investigated in rats. In normal rats, single administration of CCK-8 had no significant effect on the passive avoidance response. Treatment with ECS, CO₂, or cycloheximide markedly decreased the latency of the passive avoidance response, but CCK-8 in doses from 0.1 to 10 μg/kg could prevent the induced amnesia when injected 30 min before the training trials, immediately after foot shock or amnesic treatments, and 30 min before the first retention test. The results indicate that peripheral administration of CCK-8 is effective in preventing amnesia in the rat.     

Ethanol and cycloheximide alter protein and RNA synthesis of Cox astrocytoma cells in culture

Chronic ethanol ingestion or cycloheximide treatment results in alterations in the properties and synthesis of protein and RNA of polyribosomes in the whole brain. To analyze the effects on a homogeneous neural cell population, Cox astrocytoma (glioma) cells were grown in tissue culture media with 100 mM ethanol or 0.017 mg/ml of cycloheximide. When ethanol had been present for ten days, the cell densities remained unchanged but had markedly reduced RNA and protein contents. Furthermore, the ethanol treatment reduced the whole-cell pulse-labeling of RNA with (5–³H) orotic acid and protein with (¹⁴C) leucine in the postmitochondrial supernatant. These results suggest that chronic ethanol treatment reduced the whole cell synthesis of RNA and protein or increased their degradation. Analysis of the polyribosomes on sucrose density gradients showed that dense polyribosomal chains were decreased after the ethanol treatment, supporting the concept that the polyribosomes were degraded with an alteration in the metabolism of mRNA. The cell-free incorporation of (¹⁴C) leucine into hot TCA precipitable protein by the purified polyribosomes in the presence of ATP, GTP, a heterologous source of soluble factors, and endogenous mRNA was also reduced following the ethanol treatment, further indicating that the previous chronic exposure to ethanol had inhibited the translation of mRNA. When the control cells were grown in the presence of cycloheximide for one hour prior to harvesting, the cell densities remained unchanged, but again, as with the ethanol treatment, the polyribosomal protein and RNA yields decreased. In contrast to ethanol, however, cycloheximide treatment caused increases both in the whole-cell incorporation of labeled RNA and protein precursors into the supernatant fraction and in the cell-free incorporation of (¹⁴C) leucine into protein. These results suggest that, like the ethanol effects, cycloheximide reduces the total polyribosomes, but unlike the ethanol effects, the remaining polyribosomes have stable mRNA and rapidly incorporate radioactive amino acids, even more than untreated controls. The one-hour cycloheximide treatment also caused an increase in the ratio of dense polyribosomes to monosomes plus 40s and 60s ribosomal subunits of control cells. In addition, it increased the incorporation of the labeled precursor into protein in the polyribosomal region of the sucrose gradients of both control and ethanol treated cells, suggesting that cycloheximide inhibited the termination step of protein synthesis. When cycloheximide was present for 24 hours prior to harvesting, the ethanol treated cells, in contrast to the controls, still had increased cell-free incorporation of amino acid into protein, indicating that the stimulatory effects of cycloheximide are prolonged to 24 hours when ethanol is present. Thus, while the ethanol treatment in general inhibits polyribosomal biogenesis in the cells, it alters the complex of stimulating and then inhibiting effects of cycloheximide by preserving cycloheximide's stimulating effects on the amino acid incorporation activities of the polyribosomes.     

Gymnoascaceae and Onygenaceae as Contaminants of Skin, Hair and Nails: Gymnoascaceae und Onygenaceae als Kontaminanten von Haut, Haaren und Nägeln

Summary: Skin scrapings, hairs, and nail fragments from 58,000 dermatological patients were studied for non-pathogenic species of Gymnoascaceae and Onygenaceae by culture on Sabouraud's chloramphenicol cycloheximide agar.
Eleven species from 95 isolates were demonstrated, and five of these fungi were new to Denmark. The keratinophilic species occurred as contaminants in 0.1 % of the patients.
Zusammenfassung: Hautschuppen, Haare und Nagelspäne von 58 000 dermatologischen Patienten wurden mit Hinblick auf nichtpathogene Arten von Gymnoascaceae und Onygenaceae auf Sabourauds Chloramphenicol Cycloheximid Agar inkubiert.
In 95 Kulturen wurden 11 verschiedene Arten dieser Familien isoliert, 5 davon zum ersten Mai in Dänemark. Die keratinophilen Arten, 80 der obengenannten Kulturen, repräsentierten 0,1% der untersuchten Patienten.     

Effects of nefiracetam,DM-9384 on amnesia and decrease in cholineacetyltransferase activity induced by cycloheximide

Summary The effects of nefiracetam, [N-(2,6-dimethyl-phenyl)-2-(2-oxo-pyrrolidinyl)acetamide, DM-9384], a cyclic derivative of GABA, were investigated in the cycloheximide (CXM)-induced amnesia animal model using the passive avoidance task. Pre-training administration of DM-9384 attenuated the CXM-induced amnesia as indicated by prolongation of step-down latency. It protected against CXM-induced inhibition of choline acetyltransferase activity in the cerebral cortex. These results suggest that DM-9384 attenuates CXM-induced amnesia by interacting with AChergic neuronal system and enhancing protein synthesis in the brain.     

Effects of protein synthesis inhibition on kindling in the mouse

Mice treated with anisomycin during amygdaloid kindling failed to develop generalized seizures. Anisomycin failed to suppress fully developed seizures in kindled mice, indicating that its prophylactic effects are not secondary to a general anticonvulsant action. These results are consistent with the hypothesis that the central neuroplastic changes underlying kindling require the ongoing synthesis of proteins.     

Monosaccharide digitoxin derivative sensitize human non-small cell lung cancer cells to anoikis through Mcl-1 proteasomal degradation

Advanced stage cancers acquire anoikis resistance which provides metastatic potential to invade and form tumors at distant sites. Suppression of anoikis resistance by novel molecular therapies would greatly benefit treatment strategies for metastatic cancers. Recently, digitoxin and several of its novel synthetic derivatives, such as α-l-rhamnose monosaccharide derivative (D6-MA), have been synthesized and studied for their profound anticancer activity in various cancer cell lines. In this study, we investigated the anoikis sensitizing effect of D6-MA compared with digitoxin to identify their anti-metastatic mechanism of action. D6-MA sensitized NSCLC H460 cells to detachment-induced apoptosis with significantly greater cytotoxicity (IC50 = 11.9 nM) than digitoxin (IC50 = 90.7 nM) by activating caspase-9. Screening of the Bcl-2 protein family revealed that degradation of anti-apoptotic Mcl-1 protein is a favorable target. Mcl-1 over-expression and knockdown studies in D6-MA and digitoxin exposed cells resulted in rescue and enhancement, respectively, indicating a facilitative role for decreased Mcl-1 expression in NSCLC anoikis. Transfection with mutant Mcl-1S159 attenuated detachment-induced cell death and correlated with a remaining of Mcl-1 level. Furthermore, D6-MA suppressed Mcl-1 expression via ubiquitin proteasomal degradation that is dependent on activation of glycogen synthase kinase (GSK)-3β signaling. In addition, D6-MA also targeted Mcl-1 degradation causing an increased anoikis in A549 lung cancer cells. Anoikis sensitizing effect on normal small airway epithelial cells was not observed indicating the specificity of D6-MA and digitoxin for NSCLC. These results identify a novel cardiac glycoside (CG) sensitizing anoikis mechanism and provide a promising anti-metastatic target for lung cancer therapy.     

Sensitization of human colon cancer cells to trail-mediated apoptosis

TNF-related apoptosis-inducing ligand (TRAIL), a novel member of the tumor necrosis factor (TMF) family, is thought to induce apoptosis preferentially in cancer cells; however, increasing evidence suggests that a number of cancers are resistant to TRAIL treatment. FLICE-like inhibitory protein (FLIP), which structurally resembles caspase-8, can act as an inhibitor of apoptosis when expressed at high levels in certain cancer cells. The purpose of our present study was to determine whether human colon cancer cells are sensitive to TRAIL treatment and, if not, to identify potential mechanisms of resistance. Colon cancer cells of different metastatic potential (KMlZC, KML4A, and KM20) were found to be resistant to the effects of TRAIL when used as a single agent. FLIP expression levels were increased in all three KM cell lines. Treatment with either actinomycin D (Act D;10 μ/ml) or cycloheximide (CHX; 10 μg/ml) decreased FLIP expression levels in all three cell lines. The decrease in cellular levels of FLIP was associated with sensitization to TRAIL-mediated apoptosis, as demonstrated by enhanced cell death and caspase-3 activity compared with either Act D or CHX alone. Our findings suggest that reduction of FLIP levels by Act D or CHX renders TRAIL-resistant human colon cancer cells sensitive to TRAIL-mediated apoptosis. The combination of TRAIL along with agents such as Act D or CHX, which target proteins that prevent cell death, may provide a more effective and less toxic regimen for treatment of resistant colon cancers. Presented at the Forty-First Annual Meeting of The Society for Surgery of the Alimentary Tract, San Diego, Calif., May 2l–24, 2000, and published as an abstract in Gastroentmolog 118:A1025, 2000. Supported by grants R01 AG10885, R01 DK48498, PO1 DK35608, and T32 DK07639 from the National Institutes of Health, Bethesda, Md.     

Fast Neutron r.b.e. for Lethality and Genotoxicity in a Wild-type and a Repair-deficient Strain of Yeast

Summary

Protein synthesis is normally required for G₂-cell progression and for recovery from radiation-induced G₂-arrest. In the presence of 5mm caffeine this requirement is alleviated, indicating that the mechanism responsible for G₂ cell progression acutally remains intact in irradiated or protein synthesis inhibitor-treated cells. It is suggested that both radiation and cycloheximide-induced G₂-arrest are not, therefore, passive consequences of cellular defects, but are rather, active cellular responses to the state of cellular integrity, implying the existence of G₂ cell progression controls.