We used flow cytometry to assess the cell cycle kinetics of cultured Maden Darby canine kidney cells after exposure to paraquat. Fluorescein diacetate fluorescence was used as a marker of cell viability, while bromodeoxyuridine incorporation was detected with a monoclonal antibody and propidium iodide staining to assess DNA synthesis. Flow cytometry was performed immediately, 48 h and 96 h after exposure to paraquat for 24 h. Lactate dehydrogenase release was also measured to determine the extent of cytolysis. Flow cytometry of paraquat-treated cells showed a marked increase of the S phase population immediately after exposure, at a time when there was no increase of lactate dehydrogenase release. In contrast, the cell cycle profile returned towards normal at 48 and 96 h after paraquat exposure, but lactate dehydrogenase release increased. These findings indicate that paraquat arrested cells in the S phase and that inhibition of DNA synthesis by this agent appeared to influence cell viability because S phase block occurred before cytolysis. In addition, this method proved useful for assessing the effects of paraquat on DNA synthesis by cultured cells.

Animals↗

PubMedDate not supplied

Muscarinic receptor concentrations and dopamine release in aged rat striata.

The extent to which age-related decreases in muscarinic enhancement of K(+)-evoked dopamine release (K(+)-ERDA) from perifused striatal slices is dependent upon the loss of striatal muscarinic receptors (mAChR) was determined. Both K(+)-ERDA and mAChR (M1, M2) concentrations were assessed from the same animals (3, 5-7 and 24-27 months). Results indicated associated decreases of 70% in oxotremorine-enhanced K(+)-ERDA and 36% in Bmax (3H-QNB) (3 and 24-27 months groups). Decrease of mAChR Bmax was not the result of membrane sequestration. Although both the concentrations of M1 and M2 muscarinic receptor subtypes decline with age, only the M2 receptor decline was correlated with the age-related decreases in muscarinic enhancement of K(+)-ERDA (r = .71, p less than 0.001). Results suggest that age-related decreases in mAChR concentrations as being partially responsible for deficits in muscarinic enhancement of K(+)-evoked release of DA.

Aging↗

PubMedDate not supplied

The augmentative effect of repeated heat shock preconditioning on the production of heat shock protein 72 and on ischemic tolerance in rat liver tissue.

OBJECTIVE: Heat shock pretreatment induces heat shock protein (HSP)72 strongly in rat livers and provides the tolerance against subsequent ischemia-reperfusion injury. In this study, the effects of repeated heat shock pretreatment on the production of HSP72 in rat livers and on subsequent ischemic tolerance were investigated. METHODS: Rats pretreated with repeated heat shock were compared with those that received a single heat shock pretreatment. The production of HSP72 was analysed using Western-blotting and densitometer. At 48 h after heat shock pretreatment, all rats were subjected to warm liver ischemia for 30 or 45 min and then reperfused. Survival rate of the animals and liver functions during reperfusion were analysed. RESULTS: The production of HSP72 increased in the repeated heat shock group more than in the single heat shock group. Although there were no significant differences in animal survival or in liver functions after a 30-min ischemia between the single heat shock group and the repeated heat shock group, animal survival and liver functions after a 45-min ischemia were significantly better in the repeated heat shock group. CONCLUSION: In rats, repetition of heat shock pretreatment augmented the production of HSP72 in liver tissue and protected the liver from ischemia-reperfusion injury.

Animals↗

PubMedDate not supplied

[Proceedings: 22. On the relationship between the cell membrane and DNP-amino acid (author's transl)].

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Amino Acids↗

PubMedDate not supplied

Restriction fragment length polymorphism (RFLP) analysis in the TNF genes of patients with systemic lupus erythematosus (SLE).

Although systemic lupus erythematosus (SLE) is known to be positively associated with certain major histocompatibility complex (MHC) class I and/or class II antigens, it is not clear whether the MHC genes are the predisposing genes of the disease rather than markers for other closely linked gene(s). Because of the involvement of tumor necrosis factor (TNF) in the inflammation process and localization of the TNF genes in the proximity of the HLA-B locus, we studied the restriction fragment length polymorphism (RFLP) of the TNF-alpha and -beta genes in 20 SLE patients and 23 normal individuals using restriction endonuclease NcoI. The frequency of a 5.5 kb NcoI fragment from SLE patients was significantly higher than that from normal controls. This result suggests that the polymorphic TNF genes may be involved in the pathogenesis of SLE.

Alleles↗