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Biomedical subjects

J O Mason

Publications and source records attributed to J O Mason.

At least 55 records · Page 3Linked to original sources
PubMed1988

The half-life of immunoglobulin mRNA increases during B-cell differentiation: a possible role for targeting to membrane-bound polysomes.

The increase in abundance of immunoglobulin heavy-chain (IgH) mRNA that accompanies development of a B cell into a plasma cell is mainly due to post-transcriptional events. By constructing mu genes, whose expression is under inducible control, we determined the half-life of pulsed mu transcripts to be approximately 20 hr in plasmacytoma hosts and approximately 3 hr in B-cell lymphomas. Interestingly, a mu gene with a mutated signal sequence that is found on free (rather than membrane-bound) polysomes decays in the plasmacytoma host with a shortened half-life of 3 hr. Thus, a change in the turnover rate of IgH mRNA plays an important role in the cell-type specificity of immunoglobulin gene expression; this change may be a consequence of the fact that IgH mRNA is located in the membrane-bound polysome fraction.

Animals↗
PubMed1987

Barbiturates inhibit stress-induced analgesia.

The effect of pentobarbitone and thiopentone on stress-induced analgesia was studied in 40 male Sprague-Dawley rats. Antinociception was determined by measuring motor reaction threshold to the noxious pressure on the tail with the use of an "Analgesymeter." Stress was induced by placement of a clamp on the hind paw. The stress procedure was found to cause an increase in reaction threshold, which was partially suppressed by naloxone 0.5 mg X kg-1. Pentobarbitone in a subanaesthetic dose of 25 mg X kg-1, SC, almost completely abolished the stress-induced increase in the reaction threshold (an increase in reaction threshold from 329 +/- 33 g to 486 +/- 62 g in control group, and from 250 +/- 26 g to 273 +/- 35 g in pentobarbitone group, p less than 0.02 for the difference in the threshold changes). Thiopentone used in a dose of 25 mg X kg-1, IV, caused a loss of the righting reflex for 37 +/- 10 minutes; stress procedure applied ten minutes after regaining the righting reflex did not cause any increase in the reaction threshold (with an increase in the reaction threshold in control group from 355 +/- 50 g to 540 +/- 26 g, p less than 0.001 for the difference between the groups). The results suggest that the barbiturates in subanaesthetic doses inhibit stress-induced analgesia. Thiopentone used in an anaesthetic dose has the potential for inhibition of stress-induced analgesia in the period of recovery from anaesthesia.

Animals↗
PubMed1987

Pentobarbital and thiopental anesthetic interactions with midazolam.

The effects of midazolam-pentobarbital and midazolam-thiopental combinations on the righting reflex were studied in rats. Doses that block the righting reflex for the agents given alone and for their combinations were determined with a probit procedure and compared with an isobolographic analysis. Interactions between pentobarbital or thiopental and midazolam were found to be synergistic (supra-additive). The degree of synergism was almost identical with both combinations. The ability of barbiturates to increase the affinity of benzodiazepine receptors to midazolam may be the underlying mechanism for the observed synergism.

Anesthesia, General↗
PubMed1987

Morphine and fentanyl hypnotic interactions with thiopental.

The effects of morphine-thiopental and fentanyl-thiopental combinations on the righting reflex were studied in rats. Doses that block the righting reflex for the agents given alone and for their combinations were determined with a probit procedure and compared with an isobolographic analysis. Interaction between morphine or fentanyl and thiopental on blockade of the righting reflex were both found to be synergistic. The degree of synergism was relatively small for the fentanyl-thiopental combination; the maximal deviation from additive interaction (expected/observed ratio) for ED50 dose level was 1.15 (P less than 0.01). The degree of synergism was greater for the morphine-thiopental combination; the maximal deviation from additive interaction was 2.27 (P less than 0.001). Comparison of the results with the outcomes of opioid-barbiturate interactions in relation to blockade of purposeful movement response to tail clamping, which was antagonistic, shows that the combination of a barbiturate with an opioid gives different outcomes for different end-points of anesthesia. This suggests that the anesthetic effect of an agent is composed of several components, each with a different mechanism of action.

Animals↗
PubMed1986

Morphine and fentanyl interactions with thiopental in relation to movement response to noxious stimulation.

The effects of morphine-thiopental and fentanyl-thiopental combinations on the movement response caused by tail clamping were studied in rats. Doses that prevented movement response when the agents were given singly and when the agents were given in combination were determined by a probit procedure and compared with isobolographic analysis. With doses of the above agents sufficient to block the movement response to tail clamping (ED50 values: 4.7 (3.3-6.6) mg/kg intravenously for morphine; 8.3 (5.8-11.3) micrograms/kg intravenously for fentanyl; and 18.8 (17.9-19.7) mg/kg intravenously for thiopental) both fentanyl and, to a lesser extent, morphine have a less than additive or an antagonistic interaction with thiopental. This antagonism is a relative one that does not increase the requirement for one agent upon the addition of another agent.

Animals↗
PubMed1985

Transcription cell type specificity is conferred by an immunoglobulin VH gene promoter that includes a functional consensus sequence.

Immunoglobulin heavy chain gene transcription was studied using DNA transfection. The enhancer element identified in the mouse heavy chain locus was active in pre-B and plasmacytoma cell lines, but no activity was detected in two T cell lymphomas. However, even in the absence of the enhancer, cell type specificity of immunoglobulin gene transcription was still retained. We have used gene fusions to show that transcription cell type specificity is conferred by a VH gene promoter. Deletion analysis of this VH promoter indicates that a conserved octamer found 5' of the TATA box in immunoglobulin V genes is a functional part of the tissue-specific promoter upstream element.

Animals↗
PubMed1985

The USA Centers for Disease Control: current priorities.

Since it was first established (during World War II) the US Centers for Disease Control (CDC) has modified and extended its responsibilities as a major public health agency. Its current activities include the provision of professional training/development and the provision of epidemiologic aid and consultation. AIDS, Legionnaires' disease and toxic-shock syndrome are a few examples of the challenges faced by today's CDC.

Centers for Disease Control and Prevention, U.S.↗