bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some derivatives of polyvinylpyridine 1‐oxides and their effect on the cytotoxicity of quartz in macrophage cultures
Authors: HOLT P. F. , LINDSAY H. , BECK E. G. 
Published: July 2012

Poly(2‐vinylpyridine 1‐oxide) counteracts the pathogenic effects normally produced when quartz is injected into or inhaled by animals and the cytotoxic effects when quartz is added to macrophage cultures. The protective action of this polymer has been attributed variously to the formation of an adsorbed layer on the quartz particles, complex formation with monosilicic acid produced by the dissolution of quartz, and strengthening of the membranes or microstructures of the cells.
Stereoregular forms of poly(2‐vinylpyridine 1‐oxide), some alkyl derivatives of poly(2‐vinylpyridine 1‐oxide), poly(3‐vinylpyridine 1‐oxide) and poly(4‐vinylpyridine 1‐oxide), a copolymer of 2‐vinylpyridine 1‐oxide and 2‐n‐propenylpyridine 1‐oxide, some poly(1‐methyl‐2‐vinylpyridinium) quaternary salts, and poly(1‐methoxy‐2‐vinylpyridinium iodide), which had previously been synthesized and studied with respect to their viscosities and interaction with silicic acid, were tested for their ability to counteract the cytotoxic effects of quartz in macrophage cultures. The tests were effected both by pretreating the quartz with polymers, and by pretreating the cells.
Every polymer proved active in one or other of these conditions, but several were active in one test but inactive in the other. Some polymer quaternary salts, which do not contain the N‐oxide group, were found to be active. A remarkable difference in activity was found between the two stereoregular forms of poly(2‐vinylpyridine 1‐oxide). Pretreatment of the quartz with some of the polymers increased its cytotoxicity significantly.
Most of the results could be interpreted on the hypothesis that the polymers form an adsorbed layer on the quartz surface, but it is difficult to apply this explanation to two polymers which are inactive when used to pretreat the macrophages but are active when adsorbed on quartz.
Placental transfer of pyridostigmine in the rat
Authors: ROBERTS J. B. , THOMAS B. H. , WILSON ANDREW 
Published: July 2012

Carbon‐14 labelled pyridostigmine in single doses was given by intramuscular injection to pregnant rats, and maternal blood, foetal and placental homogenates were examined for total radioactive content, pyridostigmine and its metabolite, 3‐hydroxy‐N‐methyl pyridinium.
The level of radioactivity in all tissues was highest at 15 min and fell to negligible amounts at 24 hr. The concentrations in placenta were similar to those in maternal blood, but there was some indication of retention of radioactive drug in the placenta. The concentrations in the foetus were substantially lower, but the subsequent slow decline in concentration suggests that cumulation of the drug could occur with repeated doses.
The percentage of metabolite in the foetus was considerably higher than in placenta and blood, and the possible reasons for this are discussed.
Rapid histamine assays: a method and some theoretical considerations
Authors: COLQUHOUN D. , TATTERSALL M. L. 
Published: July 2012

An automatic method for doing assays on superfused isolated tissues has been developed using the Autoanalyser sample turntable.
Responses in the range used for assays are independent of the preceding responses when elicited at 1 min intervals. A longer interval was found to be necessary when using the conventional immersion method.
The index of precision was similar to that reported for other superfusion methods.
The assay method behaved as though it were assaying histamine selectively in two samples of material released by the anaphylactic reaction of passively sensitized guinea‐pig lung. Responses to anaphylactically released material were also independent of the preceding response at 1 min intervals.
Some theoretical considerations are discussed concerning the arrangement of doses, and the interpolation of results, in 2 + 1 dose assays. The object was to maximize speed while still allowing a valid estimate of the potency and its error.
The isolation of human plasma prekallikrein
Authors: McCONNELL D. J. , MASON BRENDA 
Published: July 2012

Summary
. The isolation of human plasma prekallikrein was achieved by fractionating human plasma on diethylaminoethyl cellulose (DEAE) in the presence of heparin.
. Heparin was shown to inhibit the activation of prekallikrein during the isolation procedure.
. The isolated prekallikrein fraction had some kallikrein activity which could be inhibited by diisopropylfluorophosphate (DFP) without affecting the ability of prekallikrein to be activated.
. The prekallikrein obtained was functionally pure in that it had no kallikrein inhibiting or activating activity. It was not physico‐chemically pure, the major contaminant being the immunoglobulin IgG.
The effect of some foreign anions on suxamethonium blockade of the isolated rat diaphragm preparation
Authors: HARRIS J. B. , LEACH G. D. H. 
Published: July 2012

Summary. The pharmacology of suxamethonium blockade of the rat phrenic nerve‐diaphragm preparation has been studied in the presence of some foreign anions.. Blockade proceeded in two distinct phases in both normal and modified Krebs solution.. In normal Krebs solution the characteristics bore no close resemblance to either depolarizing or competitive type blockade.. In the presence of foreign anions the characteristics of the blockade more closely resembled those of depolarization.. There was an increase in the sensitivity of the motor end‐plate region of the muscle to the depolarizing action of acetylcholine, carbachol and suxamethonium in the presence of the anions.. Although the anions enhanced the depolarizing activity of suxamethonium, the blocking potency of the drug was unaltered.. It is suggested that end‐plate depolarization plays little part in suxamethonium blockade of the isolated rat diaphragm and that desensitization is the primary cause of the blockade.
β‐Adrenoceptive responses in the unanaesthetized ovine foetus
Authors: PETTEN G. R. Van , WILLES R. F. 
Published: July 2012

Summary
. Isoprenaline injection into either the unanaesthetized ovine foetus or the pregnant ewe produced a transient tachycardia and hypotension in either the ewe or the foetus. No evidence was obtained for placental transfer, in either direction, of pharmacologically active isoprenaline.
. Propranolol, when given to the ewe intravenously, produced bradycardia and increased pulse pressure and inhibited the response of both the ewe and her foetus to isoprenaline. Propranolol, when given to the foetus intravenously, produced bradycardia and increased pulse pressure in both the foetus and the ewe, but only the foetal response to isoprenaline was inhibited. These data demonstrated that propranolol crossed the ovine placenta in both directions in a pharmacologically active form.
. Dose‐heart rate curves of the foetus and pregnant ewe to isoprenaline and the shift to the right of the isoprenaline dose‐response curves by propranolol were similar in both the ewe and the foetus.
. Notwithstanding the similarities between the ewe and foetus in their responses to isoprenaline or propranolol and in the antagonism of isoprenaline by propranolol, the duration of blockade following propranolol administration to the ewe was 2 to 3 times longer in the foetus compared with the ewe.
. Measurement of blood levels of propranolol showed that the maximum concentration of propranolol in foetal plasma was only 5% of that in the pregnant ewe when propranolol was infused into the ewe; the rate of clearance of propranolol was similar from the foetal and maternal plasma.
. From these data the long duration of β‐adrenoceptor blockade in the ovine foetus by propranolol cannot be fully explained. However, these data serve as examples of the dangers involved when extrapolating pharmacological actions of drugs on the foetus purely from data on foetal plasma levels of the drug.
. The data suggest that multiple doses of propranolol, given to maintain a β‐adrenoceptor blockade in the mother, could result in serious cumulative effects in the foetus.
The effect of oral contraceptive steroids on bile secretion and bilirubin Tm in rats
Authors: HEIKEL T. A. J. , LATHE G. H. 
Published: July 2012

Summary
. The effect of oestrogens and progestogens and their 17α‐ethinyl derivatives on bile flow, maximum rate of bilirubin secretion, serum and liver bilirubin has been studied.
. Both 17α‐ethinyl substituted oestrogens and progestogens greatly reduced the basal bile flow. The parent compounds, oestradiol‐17β and 19‐nortestosterone had little or no effect.
. A much larger dose of progestogens (40 mg/kg) than oestrogens (5 mg/kg) was needed.
. Between 12 and 48 h were required for 17α‐ethinyloestradiol to produce the effect.
. Bilirubin maximum secretion rate (Tm) was little affected, the only significant reduction being produced by the 3‐methyl ether of 17α‐ethinyloestradiol (mestranol).
. Rises in serum conjugated bilirubin following infusion of bilirubin were produced by 17α‐ethinyloestradiol and mestranol but not by the progestogens.
The effects of some drugs which induce agranulocytosis on the metabolism of separated human polymorphonuclear leucocytes and lymphocytes
Authors: McCURRACH P. H. , PARK JUDITH K. , PERRY W. L. M. 
Published: July 2012

Summary
. Lymphocytes and polymorphonuclear leucocytes were separated from normal human blood by the method of Rabinowitz (1964).
. The oxygen uptake, lactic acid production and glucose uptake of suspensions of these cells in vitro were measured. The values obtained agree with published data using comparable techniques.
. Amidopyrine, chloramphenicol, chlorpromazine, phenylbutazone and thiouracil, in high concentrations, depressed the oxygen uptake of polymorphs, but not that of lymphocytes. With amidopyrine, chlorpromazine and thiouracil significant inhibition was produced by concentrations equal to therapeutic plasma levels. High concentrations of the drugs, except chlorpromazine, stimulated the glucose uptake of lymphocytes but not that of polymorphs. Tetracycline and sulphisoxazole were without effect on either parameter of leucocyte metabolism.
. Because of erythrocyte contamination the lactic acid production of lymphocytes could not be determined. Lactate production by polymorphs was not affected by any of the drugs studied.
. The significance of these results is discussed. It is suggested that there is a relationship between ability to induce agranulocytosis and effect on leucocyte metabolism in vitro.
The effect of acetyl strophanthidin on the hearts of normal dogs
Authors: HAYES A. H. , McSHANE W. P. , SIDELL F. R. 
Published: July 2012

Summary
. The ED50 of acetyl strophanthidin for producing ventricular arrhythmias in normal dogs was 54·5 μg/kg intravenously.
. Doses up to and including those which caused ventricular tachycardia did not produce either atrial arrhythmias or significant aberration of A—V conduction.
. Although the classic digitalis‐induced rate and e.c.g. waveform changes may appear after administration of acetyl strophanthidin, their presence or absence have no value in predicting the subsequent development of ventricular arrhythmias.
Microinjections of tubocurarine, leptazol, strychnine and picrotoxin into the cerebral cortex of anaesthetized cats
Authors: BANERJEE U. , FELDBERG W. , GEORGIEV V. P. 
Published: July 2012

Summary
. In cats anaesthetized with intravenous chloralose, microinjections of tubocurarine, leptazol, strychnine or picrotoxin, in a volume of 1 μl, were made into the grey matter of the cerebral cortex and the electrical activity was recorded from the site of injection with the microinjection cannula which, insulated except at its tip, served as recording electrode.
. Routinely the injections were made into the gyrus splenialis or into the underlying gyrus cinguli close to the mid‐line, because the injections would then most likely be in grey and not in white matter. Injected in this way all four drugs set up foci of excitation which gave rise to synchronous firing of a large number of neurones with the result that high voltage negative spikes were recorded from the microinjection cannula.
. On injection into the gyrus splenialis the threshold dose was about 004 μg for picrotoxin, about 0·2 μg for tubocurarine, about 5 μg for strychnine and 25 to 50 μg for leptazol. Following the injection of larger doses the spike discharge continued for a few hours after picrotoxin and tubocurarine, for over an hour after strychnine, but for a few minutes only after leptazol. On injection into the gyrus cinguli the threshold doses were slightly greater and with larger doses the spikes occurred at greater frequency but were of lower voltage than in the gyrus splenialis.
. With large doses of picrotoxin injected into the gyrus splenialis the spikes developed an after‐positivity and an after‐discharge which sometimes passed into a short period of fast activity.
. The foci of excitation set up by the drugs were restricted to the site of injection because on raising or lowering the microinjection cannula the spikes recorded from it quickly decreased in voltage and then disappeared. When the injections were made close to a sulcus and the microinjection cannula, on being lowered, traversed the sulcus, the spikes changed their polarity.
. The spike discharge appears to be a consistent response to the injections of the drugs into grey matter of any part of the cerebral cortex since it was also obtained on their injection into the pyriform cortex, amygdala and area retrolimbica anterior, but not on their injection into white matter or caudate nucleus, thalamus or hypothalamus.
Central effects of picrotoxin when acting from the liquor spaces in anaesthetized cats
Authors: FELDBERG W. , GEORGIEV V. P. 
Published: July 2012

Summary
. Picrotoxin was perfused through different parts of the cerebral ventricles in cats anaesthetized with chloralose, and applied topically to the upper cervical cord in cats anaesthetized with intraperitoneal pentobarbitone sodium. With both methods, picrotoxin produced effects similar to those produced by tubocurarine; but it was active in weaker concentrations.
. Perfused through the third ventricle, picrotoxin caused shivering resulting in a rise of rectal temperature, increased motor excitability, muscle jerks, tachypnoea, mydriasis, and withdrawal of the nictitating membranes. The effects were due to an action on structures in the walls of the ventral half of the ventricle, because they occurred only on perfusion of tubocurarine through this half and not on its perfusion through the dorsal half of the third ventricle. Noradrenaline perfused through the third ventricle abolished the shivering and the rise in temperature, but did not affect the motor hyperexcitability or the muscle jerks, whereas pentobarbitone sodium similarly perfused abolished these effects as well.
. Perfused through the inferior horn of a lateral ventricle, picrotoxin caused excitation of the hippocampus. This resulted in a rhythmic discharge of high voltage negative spikes in the electrocorticogram taken from the occipital cortices. The spikes developed after‐positivity with after‐discharges and were interrupted from time to time by bursts of fast activity termed episodes. This abnormal discharge was recorded also from the perfusion cannula which was inserted into the inferior horn and acted as a lead from the surface of the hippocampus.
. Perfused through the anterior horn of a lateral ventricle picrotoxin caused a rhythmic discharge of negative spikes which was recorded from the anterior horn cannula and resulted from excitation of the grey matter in the anterior limbic area which forms part of the medial wall of the horn.
. Applied to the surface of the upper cervical cord, picrotoxin produced scratching movements.
An analysis of the coronary vascular responses to catecholamines, using a modified Langendorff heart preparation
Authors: BROADLEY K. J. 
Published: July 2012

Summary
. A modified Langendorff heart preparation from the guinea‐pig was used to analyse catecholamine responses. Contractile force, heart rate and coronary perfusion pressure were recorded.
. Four components of the vascular response could be identified.

The initial phase was a vasoconstriction mediated by α‐adrenoceptors which preceded any effects on heart rate and force.
A secondary constriction followed, which was due to the increased myocardial compression during positive inotropic and chronotropic responses.
The third, more predominant, effect was a prolonged dilatation probably associated with the increased metabolic activity of the heart.
A fourth component was a direct vasodilatation mediated by β‐adrenoceptors which was evident when small doses of catecholamines were used but was usually masked by the more pronounced metabolically linked dilatation.

. The actions of salbutamol were examined and since it caused direct vasodilatation by stimulation of β‐adrenoceptors without other myocardial effects, these adrenoceptors were classified as the β2‐type.
. I.C.I. 50,172 was employed to block selectively the myocardial effects due to stimulation of β1‐adrenoceptors and leave the vasodilator β2‐adrenoceptors unaffected.
. Adrenaline, noradrenaline and isoprenaline were compared at two dose levels, in the presence or absence of effects on heart rate and force.
. Constrictor or dilator effects were found in the absence of other effects and were shown to depend to some extent on the rate of coronary perfusion.
Effects of catecholamines infused into the brain of young chickens
Authors: MARLEY E. , STEPHENSON J. D. 
Published: July 2012

Summary
. (–)‐Noradrenaline, (–)‐α‐methylnoradrenaline and (–)‐isoprenaline were infused into various brain regions of 12–21 day chicks. When infused into the hypothalamic area, but not the cerebral hemisphere or posterior mesencephalon, these amines produced behavioural sleep, lowered temperature and blood pressure and reduced oxygen consumption; electrocortical sleep activity usually ensued but this was not marked and frequently dissociation between electrocortical activity and behaviour occurred. After monoamine oxidase inhibition, which prolonged the action of noradrenaline, dopamine had similar effects.
. The effects of the catecholamines were prevented or substantially reduced by pretreatment with phenoxybenzamine given intravenously or into the hypothalamus but not by intravenous injection of propranolol. However, intrahypothalamic infusion of propranolol prevented the temperature, but not the behavioural effects of noradrenaline. The implications of this are discussed.
. That the effects were similar but more intense, apart from electrocortical changes, and of longer duration than those seen after intravenous injection of catecholamines suggests that in young chicks these amines penetrate from the blood into the brain and elicit their effects through a localized region, presumably the hypothalamus.
An investigation of α‐methyl amino‐acids and their derivatives on isolated tissue preparations
Authors: GULATI O. D. , PARIKH H. M. , RINGE S. Y. , SHERLEKAR M. L. 
Published: July 2012

Summary
. The ability of α‐methyl amino‐acids and their corresponding amines to restore the sympathomimetic actions of tyramine, and the uptake of the amino‐acids and the amines, were studied in isolated tissue preparations obtained from reserpine pretreated animals.
. Tyramine relaxed isolated rat ileum preparations from non‐reserpinized rats but not from reserpine treated animals. α‐Methyldopa, α‐methylnoradrenaline and lower concentrations of metaraminol restored the responses of reserpinized preparations. α‐Methyldopamine, α‐methyl‐m‐tyrosine, α‐methyl‐p‐tyrosine and higher concentrations of metaraminol did not do so. The restoring effect of α‐methyldopa was blocked by disulphiram. α‐Methyl‐p‐tyrosine or α‐methyl‐m‐tyrosine blocked the restoring action of α‐methyldopa but not of α‐methylnoradrenaline. Cocaine blocked the restoration of responses to tyramine by α‐methylnoradrenaline but not by α‐methyldopa. α‐Methyldopa and α‐methylnoradrenaline failed to restore responses to tyramine in the presence of sodium‐free Tyrode solution.
. Tyramine increased the perfusion pressure in isolated rabbit ear preparations obtained from non‐reserpinized animals but was very much less active in preparations obtained from reserpine treated animals. α‐Methyldopa, α‐methyl‐m‐tyrosine, α‐methylnoradrenaline, α‐methyl‐p‐tyrosine and metaraminol restored the effects of tyramine. α‐Methyldopamine did not do so. The restoring effect of α‐methyldopa and α‐methyl‐m‐tyrosine was blocked by disulfiram. α‐Methyl‐p‐tyrosine blocked the restoring effect of α‐methyl‐m‐tyrosine.
. Tyramine produced positive inotropic effects in isolated rabbit heart preparations. This was either reduced or absent in preparations obtained from reserpine pretreated animals. α‐Methyldopa, α‐methylnoradrenaline, α‐methyl‐m‐tyrosine and metaraminol restored the responses to tyramine. α‐Methyldopamine and α‐methyl‐p‐tyrosine did not do so.
Effect of caerulein on protein synthesis and secretion in the guinea‐pig pancreas
Authors: MELDOLESI J. 
Published: July 2012

Summary
. Caerulein produced a striking increase in the rate of secretion of the guinea‐pig pancreas. When tested in vivo with pancreatic slices its optimal concentration was found to be 2.5 ng/ml. In vivo the intravenous injection of 400 ng/kg and the subcutaneous injection of 4 μg/kg of the drug produced marked secretory responses.
. Neither incubation of pancreatic slices in vitro for various lengths of time in the presence of caerulein nor the intravenous injection of the drug brought about any detectable changes in the rate of 14C‐l‐leucine incorporation into protein of pancreatic slices incubated in vitro. By contrast, a two‐fold increase in the incorporation of leucine was found in fasting animals injected subcutaneously with caerulein twice a day for 4 days. The same treatment in fed animals, or one single dose of caerulein injected subcutaneously 4 h before killing in guinea‐pigs starved for 4 days did not affect the rate of incorporation. Moreover the long term treatment with the cholinergic segretagogue bethanechol in fasted guinea‐pigs was also ineffective.
. It is concluded (a) that in the guinea‐pig pancreas, stimulation of enzyme secretion does not affect per se the rate of synthesis of digestive enzymes; and (b) that the increase of protein synthesis elicited by caerulein is critically dependent both on the nature of the segretagogue (that is, it is elicited by the polypeptide but not by a cholinergic drug) and on the experimental conditions (it is evident only in fasted animals after prolonged treatment).
Recovery of hypothalamo‐pituitary‐adrenal function in the rat after prolonged treatment with betamethasone
Authors: HODGES J. R. , MITCHLEY SUSAN 
Published: July 2012

Summary
. Betamethasone caused growth retardation, adrenal atrophy and impaired hypothalamo‐pituitary‐adrenal (HPA) activity in the rat.
. In spite of the profound impairment, recovery of normal HPA function was rapid, but the growth retardation persisted.
. The ability of the pituitary gland to secrete basal corticotrophin (ACTH), recovered more rapidly and the adrenocorticotrophic response to stress less rapidly than the ability of the adrenal cortex to respond to ACTH.
. The degree of HPA suppression was not determined by the total dose of steroid.
. The possible significance of the results is discussed.