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Biomedical subjects

J Houston

Publications and source records attributed to J Houston.

At least 37 records · Page 2Linked to original sources
PubMed1989

Effects of a new neuromuscular blocking agent (Org 9426) in anaesthetized cats and pigs and in isolated nerve-muscle preparations.

The effects of Org 9426 (the 2-morpholino, 3-hydroxy, 16N-allyl pyrrolidino analogue of vecuronium) were studied in anaesthetized cats and pigs and in isolated nerve--muscle preparations using tension and intracellular recording techniques. In isolated preparations, the effects of Org 9426 were antagonized by neostigmine. No contracture of the chick muscle preparation occurred. Org 9426 reduced the amplitude of endplate currents (EPC) in rat and snake muscle, but had no major effects on EPC decay characteristics, indicating a lack of endplate channel blocking action. In anaesthetized animals, no fasciculations were observed and the neuromuscular block was associated with tetanic and train-of-four fade and was antagonized by neostigmine. In anaesthetized cats and pigs, Org 9426 was approximately 20% as potent as vecuronium, its onset of action was twice as rapid as that of vecuronium in the cat and its duration of action was similar to that of vecuronium in both cats and pigs. It blocked the bradycardia produced by vagal stimulation only in doses greater than those necessary to produce neuromuscular block (ratios 7.2 in the cat and 4.4 in the pig--10-14% of the corresponding ratios for vecuronium). Ganglion block was seen only at doses several times those producing vagal block. In general the effects of Org 9426 on the cardiovascular system were slight, a small depressor effect occurring at high doses in the cat. The 17-hydroxy analogue, the potential metabolite of Org 9426, was approximately 20 times less potent than Org 9426 and is thus unlikely to contribute to the neuromuscular block produced by the parent compound.

Action Potentials↗
PubMed1989

A comparison of the neuromuscular blocking and autonomic effects of two new short-acting muscle relaxants with those of succinylcholine in the anesthetized cat and pig.

The actions of two new steroidal nondepolarizing neuromuscular blocking agents, structurally related to vecuronium, have been compared with those of succinylcholine in anesthetized cats and pigs. Both new compounds (Org 7617 and Org 9616) exhibited properties typical of nondepolarizing relaxants in each species. Org 9616 was one-fifth (ED50 cat tibialis 154 micrograms.kg-1) and Org 7617 was one-tenth (ED50 cat tibialis 287 micrograms.kg-1) as potent as vecuronium as a neuromuscular blocking drug. Both compounds produced rapidly developing muscle relaxation in cats that, like that of succinylcholine, was transient in time course (onset/duration of action--tibialis anterior muscle: Org 7617 1.6/3.9 min; Org 9616 1.5/4.3 min; succinylcholine 1.7/5.7 min). In pigs that were used as a predictor of duration of action in humans, both Org 7617 and Org 9616 also produced short-lived neuromuscular blockade. The neuromuscular blocks produced by Org 7617 and Org 9616 were readily reversed by neostigmine. Both compounds blocked the heart rate responses to vagal stimulation at doses higher than those required to produce neuromuscular block. The vagal:neuromuscular blocking ratio for Org 7617 was 10, and for Org 9616 was 17. These compare to approximate published values for vecuronium, atracurium, and pancuronium of 60, 25, and 3, respectively. Ganglion block was only seen at 30-60 times the neuromuscular blocking doses. Both compounds produced a decrease in arterial blood pressure. This was more pronounced with Org 7617. In addition, Org 9616 produced a slight increase in heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1988

Structure:action relationships among some desacetoxy analogues of pancuronium and vecuronium in the anesthetized cat.

The hypothesis that the neuromuscular blocking potency of pancuronium and vecuronium depends on the two acetylcholine moieties present at positions 3 and 17 was tested in cats by examining the neuromuscular profile of several desacetoxy analogues. Blockade of sciatic nerve-induced contraction of the tibialis and soleus muscles, as well as the effects on vagal-induced bradycardia and on sympathetically induced contractions of the nictitating membrane, were studied. The bis-desacetoxy analogue of pancuronium (ORG 7931) was one-fifth as potent as the parent compound as a neuromuscular blocking drug and as a vagolytic agent, but the neuromuscular block was faster in onset and shorter in duration than that produced by pancuronium. The desacetoxy analogues of vecuronium (ORG 8730 and ORG 8764) also were less potent neuromuscular blocking drugs, and, in addition, produced more vagal block than did vecuronium itself. The neuromuscular block produced by these desacetoxy analogues was of more rapid onset and shorter duration than that produced by vecuronium. The results thus showed that the greater neuromuscular blocking potency of pancuronium and vecuronium is lost after removal of one or both of the acetylcholine moieties. An analysis of the relationship between neuromuscular blocking dose and duration of action revealed that it was reciprocal, and it is suggested that a nondepolarizing equivalent of suxamethonium, when discovered, may necessarily be a drug of relatively low potency.

Animals↗
PubMed1987

Acute megakaryocytic leukemia. Flow cytometric analysis of DNA content at diagnosis and during the course of therapy.

Flow cytometry (FCM) for the determination of DNA content and cell cycle analysis was performed on multiple bone marrows from a case of acute megakaryocytic leukemia in a 71-year-old woman. Two aneuploid (multiploid) peaks were present at diagnosis. This multiploidy was a stable characteristic when studied temporally. The disappearance of the peaks in the bone marrow specimens directly correlated with complete remission morphologically. These findings further support the concept of FCM as an adjunct to morphologic study in identifying residual tumor burden.

Aged↗
PubMed1987

Tobacco and alcohol use among Australian secondary schoolchildren.

A national survey of 23,359 Australian schoolchildren who were predominantly in the age range of 12-17 years was undertaken in 1984 to determine their levels of use of tobacco and alcohol. The prevalence of current smoking behaviour (that is, at least one cigarette in the past week) rose with age to 34% among girls and 29% among boys at 15 years of age. The prevalence of current drinking behaviour (that is, at least one drink in the past week) rose with age to 49% among girls and 56% among boys at 17 years of age. Very few pupils reported daily drinking but from 15 years of age between 12% and 14% of the sampled students reported smoking every day. Boys who currently smoked and drank reported higher consumptions of tobacco and alcohol than did girls who currently smoked and drank. Most smoking and drinking took place at weekends. Normal responses for intention to smoke in the future, and for drinkers and smokers "self-referent labels" are also reported, and it is suggested that health education programmes for schoolchildren usefully could be focused on these psychological factors.

Adolescent↗
PubMed1984

Mental distress in mothers of young children in Harrogate.

Two hundred and forty women with young children who were patients in a Harrogate general practice were studied. About a third of them were found to be suffering from 'mental distress'. Younger mothers were more affected. The number of spacing of their children were not related to symptoms of depression and anxiety, but poor personal relationships and difficulties getting out and about were so related, despite relatively affluent circumstances. Children of distressed mothers were more inclined to be disturbed. A controlled trial using amitriptyline involving 25 of the women suggested that this drug can improve depressive symptoms under these circumstances and that the improvement is likely to be maintained over the course of a year.

Adult↗