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Biomedical subjects

D M Jackson

Publications and source records attributed to D M Jackson.

At least 181 records · Page 10Linked to original sources
PubMed1977

The effect of delta 9-tetrahydrocannabinol, cannabidiol, and cannabinol on the anaesthesia induced by various anaesthetic agents in mice.

delta 9-Tetrahydrocannabinol (2.5-80.0 mg/kg) significantly prolonged the anaesthesia induced by ketamine, pentobarbitone, thiopentone, propanidid, and Alfathesin in a dose-dependent manner. Cannabinol and cannabidiol (both 5.0-80.0 mg/kg) were essentially inactive, except that cannabidiol prolonged pentobarbitone-induced anaesthesia. The interaction of delta 9-tetrahydrocannabinol with the anaesthetic agents was postulated to be due to a centrally mediated action, whereas the effect of cannabidiol on pentobarbitone-induced anaesthesia probably depended on a metabolic interaction. The interaction between the cannabinoids in influencing anaesthesia induced by the above agents was examined, and the interactions were found to be complex.

Alfaxalone Alfadolone Mixture↗
PubMed1977

Burn excision by a caron-dioxide laser.

When the 'Sharplan' 50 W carbon-dioxide laser was used for burn excision, blood-loss was reduced compared with that experienced during scalpel excision. This advantage was more than offset, however, by the increased operating-time and increased physical effort required to maintain a firm, prolonged pull on the burned tissue during excision. A more powerful laser might overcome these disadvantages.

Adolescent↗
PubMed1977

Ethanol and delta9-tetrahydrocannabinol interactive effects on human perceptual, cognitive and motor functions. II.

Fifteen paid student volunteers (10 male, five female) were used in a double-blind crossover experiment to further investigated the effects of delta9-tetrahydrocannabinol (THC), alone and in combination with ethanol, on perceptual, cognitive and motor functions. Both ethanol (0-54 g/kg) and THC (15 MG/70 KG) WERE GIVEN ORALLY. Ethanol was not very effective in in+uencing performance but this dose of THC produced marked decrements, predominantly in the latter part of the experiment. When they were given together, an early additive effect was apparent, but later, there was a suggestion of antagonism in that subjects who received the drug combination performed better than those who were given THC along. The interaction between THC and ethanol was considered to be complex.

Adolescent↗
PubMed1977

Antagonism by locally applied dopamine into the nucleus accumbens or the corpus striatum of alpha-methyltyrosine-induced disruption of conditioned avoidance behaviour.

Male Sprague-Dawley rats were trained to avoid an electric shock in a two-way shuttle-box. The local application of dopamine into the nucleus accumbens or the corpus striatum was found to antagonize the suppression of conditioned avoidance behaviour induced by systemically administered alpha-methyltyrosine, emphasizing the importance of these dopamine-rich brain structures in mediating conditioned avoidance behaviour.

Animals↗
PubMed1977

The demonstration of a change in responsiveness of mice to physostigmine and atropine after withdrawal from long-term haloperidol pretreatment.

Mice, administered haloperidol 3 mg/kg/day, in their drinking water for 21 days, were tested for their responsiveness to cholinergic and anticholinergic drugs 4 days after withdrawal from haloperidol (or vehicle). Haloperidol-treated animals administered methylhyoscine (1 mg/kg i.p.) and various doses of physostigmine (5 to 1215 microgram/kg) displayed significantly less depression of locomotor activity than vehicle-treated animals. Atropine, 5 mg/kg, whilst ineffective in producing locomotor stimulation in vehicle-treated animals, produced marked stimulation in haloperidol-treated animals. Methylatropine (5 mg/kg) did not produce significant stimulation in either group. Dopamine receptor supersensitivity was present in these animals as haloperidol-treated mice, pretreated with alpha-methyltyrosine and reserpine, displayed a significantly greater locomotor response to apomorphine than did vehicle-treated animals. The data support the hypothesis that long-term administration of haloperidol produces an apparent hyposensitivity of central muscarinic receptors.

Animals↗
PubMed1977

New orally effective chromosome derivatives for the treatment of asthma.

Two new chromone derivatives have been identified which possess oral anti-allergic activity in the rat PCA model of immediate hypersensitivity. They may have a wider spectrum of anti-allergic activity than disodium cromoglycate (SCG) since they are effective in in vitro tests involving sensitized basophils, in which SCG is inactive. Both compounds, when given orally, provide relief from experimental and clinical asthma in man.

Animals↗
PubMed1977

5-hydroxytryptamine depletion with para-chlorophenylalanine: effects on eating, drinking, irritability, muricide, and copulation.

Forty-four male rats were tested for eating, drinking, irritability, and copulation before and after intraperitonial para-chlorophenylalanine (PCPA) or control injections. Eleven of these rats were tested for muricide before and after PCPA injections (Group 1), while 18 others were tested only after PCPA injections (Groups 2). Group 1 rats received four 350 mg/kg PCPA injections spaced 6 days apart and showed hyperdipsia, weight loss, and a 24% increase in muricide. Group 2 rats received five daily 100 mg/kg PCPA injections repeated 11 days later and showed hyperdipsia and weight loss; in addition, 78% of them killed mice. Neither group showed significant changes in copulation. At the end of the experiment, t6 rats from Group 2 that were irritable and killed mice were injected intraperitonially with 5-hydroxytryptophan (80 mg/kg). Five of these rats lost their irritability and four stopped killing. The various behavioral changes were not corrleated significantly either with each other or with the degree of 5-hydroxytryptamine depletion. This tentatively suggests that PCPA may produce its effects on behavior by other means in addition to 5-hydroxytryptamine depletion.

Aggression↗
PubMed1977

The effects of pentobarbitone and chloralose anaesthesia on the vagal component of bronchoconstriction produced by histamine aerosol in the anaesthetized dog.

1 Total lung resistance (R(L)) and dynamic lung compliance (C(dyn)) were measured in dogs anaesthetized with pentobarbitone or chloralose and subjected to aerosols of histamine during 4 successive inspirations.2 Histamine caused concentration-dependent increases in R(L) and decreases in C(dyn). A significant vagal component was involved, but only when chloralose was employed and then only in the R(L) response.3 The resting values of R(L) and C(dyn) were similar regardless of which anaesthetic was used and remained essentially the same if the vagi were cooled.4 Electrical stimulation of the efferent vagi caused large increases in R(L) of dogs given chloralose and these effects were attenuated by the administration of pentobarbitone. Such stimulation was relatively ineffective in dogs given pentobarbitone alone.5In vitro, electrical field stimulation caused contractions of dog trachealis muscle. The responses were reduced by pentobarbitone in concentrations approximating to plasma levels in the anaesthetized dogs (1 to 5 x 10(-4) M), but the effects of exogenous acetylcholine were unaltered. The inhibition was dose-dependent, reversed by washing and unaltered by hexamethonium.6 The results suggest that pentobarbitone inhibits the vagal component of histamine-induced bronchoconstriction in the dog by an action on the efferent pathway. Furthermore, pentobarbitone acts either by blocking transmission along postganglionic parasympathetic nerves or by preventing the release of acetylcholine from the nerve endings in the lung.

Aerosols↗
PubMed1977

The effects of sodium cromoglycate on histamine aerosol-induced reflex bronchoconstriction in the anaesthetized dog.

1 The effects have been studied of sodium cromoglycate (SCG), given by aerosol or intravenously, on reflex bronchoconstriction induced by histamine aerosol in the anaesthetized dog. 2 Four breaths of an aerosol generated from a 2% solution of SCG significantly inhibited the vagally mediated increase in total lung resistance (RL) produced by histamine. 3 SCG given intravenously as bolus injections (5-500 microgram/kg) produced a dose-dependent reversal of a sustained reflex bronchoconstriction induced by histamine aerosol. Propranolol (500 microgram/kg) did not prevent this reversal. 4 SCG did not inhibit the increase in RL produced by supramaximal electrical stimulation of a vagus nerve. 5 The possibility is discussed that SCG may reduce the activity of lung irritant receptors in the anaesthetized dog.

Aerosols↗
PubMed1976

The interaction of ethanol and delta9-tetrahydrocannabinol in man: effects on perceptual, cognitive and motor functions.

Twelve paid student volunteers (8 male, 4 female) were used in a double-blind crossover experiment to investigate the effects of delta9-tetrahydrocannabinol (THC) alone, and in combination with ethanol, on human perceptual, cognitive and motor functions. Both THC (10 mg/70 kg) and ethanol (0-5 g/kg) had little effect when administered alone. The combination of drugs, however, induced a significnat decrement in performance in some of the tests and this interaction was considered to be at least additive. The peak blood ethanol concentration was higher (P = 0-05) when subjects received both ethanol and THC than when they received ethanol alone.

Adolescent↗
PubMed1976

The demonstration of a change in adrenergic receptor sensitivity in the central nervous system of mice after withdrawal from long-term treatment with haloperidol.

Mice, administered haloperidol (3 mg/kg/d) in their drinking water for 21 days, displayed, 4 days after cessation of the haloperidol-treatment, marked locomotor stimulation to clonidine (100 or 500 mug/kg) which lasted for about 6 h. 25 mug clonidine/kg was inactive. Premedication with FLA-63 (25 mg/kg) blocked the difference in stimulation after clonidine between the haloperidol- and vehicle-treated animals, but locomotor activity was still present in both groups. Haloperidol-treated animals displayed a supersensitive response to dexamphetamine. The difference in stimulation produced by dexamphetamine in the two groups was completely blocked by phenoxybenzamine (2.5 mg/kg), phentolamine (10 mg/kg), which drugs did not, however, block the locomotor stimulation produced by dexamphetamine in vehicle-treated animals. Pimozide (3 mg/kg) blocked all locomotor stimulation produced by dexamphetamine in both vehicle- and haloperidol-treated groups, while 1 mg/kg completely blocked the dexamphetamine response in vehicle-treated animals but not in haloperidol-treated animals. FLA-63 (25 mg/kg) blocked the difference in response between the haloperidol- and vehicle-treated groups to dexamphetamine, but did not antagonise the stimulation in the vehicle-treated animals. The data suggest that long-term haloperidol treatment leads to the development of "supersensitive" adrenergic receptors in the central nervous system, which, appropriately stimulated, effect an increase in locomotor activity. Moreover, the results indicate that a large component of the supersensitive response to dexamphetamine observed after long-term haloperidol-treatment is due to adrenergic receptor supersensitivity. However, the dopamine receptor (which was shown to be supersensitive to apomorphine) is of fundamental importance because phenoxybenzamine and phentolamine, while blocking the supersensitive response to dexamphetamine, failed to block the response to dexamphetamine in vehicle-treated animals, which was, however, blocked by pimozide.

Adrenergic alpha-Antagonists↗
PubMed1976

The interaction between prostaglandin E1 and delta 9-tetrahydrocannabinol on intestinal motility and on the abdominal constriction response in the mouse.

The interaction between delta9-tetrahydrocannabinol (THC) and PGE1 was studied using two pharmacological parameters-the rate of passage of a charcoal meal through mouse small intestine and the abdominal constriction response in the mouse. PGE1 administered intraperitoneally produced a dose-dependent decrease in intestinal motility, and this effect was antagonized by low (0.25 mg/kg) doses of THC and potentiated by higher doses of THC (1 mg/kg). Kinetic analysis suggested that the interaction was of a mixed but predominantly competitive type. PGF2alpha produced an increase in intestinal motility but this was not dose-dependent. THC antagonized the effect of PGF2alpha in a dose-dependent manner suggestive of a physiological antagonism. THC (0.25-2 mg/kg) antagonized the dose-dependent PGE1 abdominal constriction response in a fashion which suggested a mixed (though mainly competitive) antagonism. It would ssem, therefore, that on the two pharmacological parameters studied THC appears to be interacting with PGE1 at the same receptor site. Although the doses of THC used are within the range of those used in man, it is not implied that these results are necessarily implicated in the psychoactivity of the drug.

Analgesia↗
PubMed1976

Topical chemoprophylaxis with silver sulphadiazine and silver nitrate chlorhexidine creams: emergence of sulphonamide-resistant Gram-negative bacilli.

Controlled trials of 0.5% silver nitrate compresses (SN), 1% silver sulphadiazine cream (SSD), and a cream containing 0.5% silver nitrate and 0.2% chlorhexidine digluconate (SNC) showed that all were comparably effective in protecting burns from infection. SN compresses were much less active against miscellaneous Gram-negative bacilli than the other preparations, and the mean morning and evening temperatures and respiration rates in the patients treated with SN compresses were higher then those of patients treated with SSD. Pseudomonas aeruginosa and Proteus spp, though rare in all groups, were less often found in the patients treated with SN compresses. Sulphonamide-resistant Gram-negative bacilli became predominant during the trial of SSD cream on extensive burns and the prophylactic effectiveness of that preparation was thus reduced in the later stages of the trial.

Administration, Topical↗
PubMed1976

Effect of cannabinoids on the abdominal constriction response in mice: within cannabinoid interactions.

After oral administration to mice, delta9-tetrahydrocannabinol (THC) and cannabinol (CBN) caused a dose-dependent suppression of the abdominal constriction response to formic acid. Cannabinol was 50 times less active than THC and cannabidiol (CBD) was without effect. The effects of THC and CBN were additive. CBD antagonised the antinociceptive effects of both THC and CBN in a dose-dependent manner.

Abdomen↗