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Biomedical subjects

P R Knight

Publications and source records attributed to P R Knight.

At least 91 records · Page 5Linked to original sources
PubMed1981

Inhibiting effects of enflurane and isoflurane anesthesia on measles virus replication: comparison with halothane.

Replication of measles virus in BSC cells was studied in the presence of enflurane (2-chloro-1,1,2-trifluoroethyl difluoromethyl ether), a commonly used volatile anesthetic agent, and its isomer, isoflurane (1-chloro-2,2,2-trifluoroethyl difluoromethyl ether). At clinical concentrations of the anesthetics (up to 4%), cell division was retarded, whereas only minimal toxic cellular effects were observed. The appearance of progeny virus from the cell cultures exposed to these anesthetics was decreased in a dose-related manner. Incorporation of [(3)H]uridine into measles virus nucleocapsids also decreased progressively with increasing anesthetic concentrations. In comparing the inhibition of measles virus replication in the presence of halothane (2-bromo-2-chloro,1,1,1-trifluoroethane), enflurane, or isoflurane, it was found that both inhibition of the appearance of infectious virus at 48 h postinfection and incorporation of [(3)H]uridine into measles virus nucleocapsids were proportional to the anesthetic concentrations. An equivalent degree of effect was produced by anesthetically equivalent concentrations of the three anesthetics (minimal alveolar concentration) but not by absolute concentrations. In addition, recovery of infectious virus synthesis from the inhibition encountered during exposure of infected BSC cells to halothane or isoflurane was also investigated. In cultures exposed to halothane or enflurane, recovery of infectious virus synthesis was rapid and complete. Recovery of virus synthesis was slower after isoflurane removal and did not reach the peak control titers of infected cultures not exposed to the anesthetic. Treatment with halothane resulted in the formation of a preponderance of slowly sedimenting virus nucleocapsid particles which contained less than full-length ribonucleic acids after anesthetic removal. Neither enflurane nor isoflurane treatment of BSC cultures resulted in the formation of significant levels of these slowly sedimenting particles with short genomes after anesthetic removal.

Capsid↗
PubMed1981

Atelectatic tympanic membrane reversal by nitrous oxide supplemented general anesthesia and polyethylene ventilation tube insertion. A preliminary report.

In certain instances an adherent atelectatic tympanic membrane (Sade Stage IV) may be successfully elevated off the promontory and ossicles by the use of nitrous oxide anesthesia and restored to a normal position and configuration by polyethylene ventilation tube insertion. Criteria of reversibility and long term follow-up of the tympanic membranes so restored remain to be elucidated.

Anesthesia, General↗
PubMed1980

Anesthetic action and virus replication: inhibition of measles virus replication in cells exposed to halothane.

Replication of measles virus in BSC cells was studied in the presence of halothane, a commonly used volatile anesthetic. At clinical concentrations of the anesthetic, appearance of progeny virus was decreased in a dose-related manner. This inhibition was reversible as the removal of halothane allowed virus replication to be resumed. Studies attempting to elucidate the mechanism of action of the anesthetic inhibition of virus replication revealed that halothane did not directly inactivate the virus particle or prevent viral adsorption to the cell. Infectious virus and nucleocapsid production were decreased or stopped, depending on the anesthetic dosage used. Direct immunofluorescent staining for measles virus antigen was negative in cells treated at the higher concentrations of halothane. Recovery of nucleocapsid production started within a few hours after removal of halothane. Furthermore, the combined inhibitory effects on viral ribonucleic acid synthesis of 5-azacytidine and halothane were additive. This evidence suggests that inhibition of measles virus replication occurs at or before ribonucleic acid synthesis.

Anesthesia↗
PubMed1973

Activation of a latent measles virus infection in hamster cells.

The characteristics of infectious measles virus released from latently infected hamster embryo fibroblast cells are described. Low levels of virus were released spontaneously when the cultures were incubated at 37 C; this phenomenon was observed 19 passages after the cells had been exposed to the virus and has continued through cell passage 45. The virus yield could be significantly increased by cocultivation of the hamster cells with BSC-1 cells or incubation of the latently infected cells at 33.5 C rather than at 37 C. Measles virus released after cocultivation demonstrated increased cytopathology in cell culture and reduced temperature sensitivity when compared to the virus released at 33.5 C. After cell passage 45, there was an increase in spontaneous release of virus. However, the viruses recovered by cocultivation or temperature release after cell passage 45 were nearly identical. These observations suggest a possible mechanism for measles virus activation in cells latently infected with this virus.

Animals↗