Monoaminergic modulation of the sensitivity of neurones in the cingulate cortex to iontophoretically applied substance P

The interactions of noradrenaline (NA) and 5-hydroxytryptamine (5-HT) with substance P (SP) were studied on single neurones in the anterior cingulate cortex of the rat. Iontophoretic application of 5-HT potentiated the excitatory responses of some neurones to SP and reduced responses of others. However these effects were usually accompanied by parallel changes in baseline firing rate i.e. increase and decrease respectively. In studies where carbachol (CCh) was used as a control the excitatory responses to this substance were always altered in a similar fashion to those to SP. The effects of NA on SP-responses were more consistent. This amine caused a reduction of response to SP regardless of whether there was an increase, decrease, or no change in baseline firing rate. Responses to SP could be reduced on many cells in the absence of changes in response to CCh and even on some cells where CCh responses were concurrently enhanced. Lesions of the locus coeruleus which resulted in a depletion of NA in the ipsilateral cingulate cortex gave rise to a substantial increase in sensitivity of neurones to SP two weeks later. However, lesions of the median raphe(MR)-nucleus which strongly reduced cortical 5-HT had no detectable effect on SP-responses. The data indicate that both NA and 5-HT can alter cortical neurone-sensitivity to SP but that the former amine may be involved in a more specific and possibly a functional interaction.

Microinjection of vasopressin into the locus coeruleus of conscious rats

To determine whether vasopressin plays a role in central neural control of cardiovascular function by acting on the locus coeruleus we monitored arterial pressure and heart rate responses to graded injections of vasopressin (1-30 ng, 0.1-0.3 microliter) in the locus coeruleus of conscious, restrained rats. Cannulas were stereotaxically implanted in the locus coeruleus 2-5 days prior to experiment. Injections of vasopressin into the locus coeruleus produced dose-related increases in mean arterial pressure (12 +/- 2 to 57 +/- 6 mmHg) and heart rate (27 +/- 6 to 123 +/- 16 beats/min), which lasted over 1 h at the highest dose. Injection of the antipressor vasopressin antagonist d(CH2)5Tyr(Me) arginine vasopressin (10 ng) into the locus coeruleus blocked the cardiovascular responses to vasopressin. Administration of vasopressin into an area lateral to the locus coeruleus had no effect on mean arterial pressure but produced an increase in heart rate. Equivalent doses of saline, angiotensin II, and norepinephrine (NE) had minimal or opposite (NE) effects on arterial pressure and heart rate. Peripheral alpha-adrenergic blockade with phentolamine and beta-adrenergic blockade with propranolol blocked the cardiovascular responses to injection of vasopressin in the locus coeruleus. These results suggest that vasopressin may act in the region of the locus coeruleus to exert a central action on the cardiovascular system that is mediated by a stimulation of sympathetic outflow.

Atracurium in the myasthenic patient

The use of the new competitive muscle relaxant, atracurium, is described in five myasthenic patients presenting for thymectomy. With an initial dose of 0.1 mg/kg, that is approximately one-fifth of that normally used, and incremental doses of 0.02-0.04 mg/kg, satisfactory clinical conditions were achieved. Neuromuscular function was monitored throughout using the train-of-four mechanical twitch response, and residual neuromuscular blockade was reversed satisfactorily at the end of the procedure with neostigmine 5.0 mg. A marked increase in the magnitude of the first twitch of the train-of-four to greater than control levels, accompanied by pronounced fade, was found on reversal. In reduced dosage and with careful neuromuscular monitoring, atracurium is safe to use in the myasthenic patient.

Multiple changes in the sensitivity of cingulate cortical neurones to putative neurotransmitters in ageing rats: substance P, acetylcholine and noradrenaline

The responsiveness of neurones in the anterior cingulate cortex to iontophoretically applied substance P(SP), acetylcholine (ACh), noradrenaline (NA) and GABA was compared in young (3-4 months) and old (24-30 months) rats. Neurones in the old rats were less sensitive to the depressant effects of NA but not GABA. These cells were also less sensitive to the excitatory actions of ACh but markedly more sensitive to those of SP. Such changes in responsiveness could be involved in the deficits in cerebral function which often occur in old age.

Comparison of vecuronium, atracurium and tubocurarine in normal patients and in patients with no renal function

Vecuronium (initial dose 0.1 mg kg-1; incremental doses 0.04 mg kg-1) was given to 21 normal and 21 anephric patients. There were no gross differences between the two groups in the effect or in the duration of action of either initial or incremental doses, except in two anephric patients who were resistant to the agent. Reversal with neostigmine was satisfactory. In normal patients the initial dose of vecuronium was slower in onset of action than was atracurium 0.5 mg kg-1 (26 patients): the first two incremental doses of vecuronium were administered significantly earlier than the corresponding increments of atracurium (0.2 mg kg-1), but the duration of action of increments over-all was not greatly different. However, in anephric patients, except in the resistant patients, the behaviour of vecuronium was similar to that of atracurium (26 patients). A comparison with an initial dose of tubocurarine 0.5 mg kg-1 given to 20 anephric patients and tubocurarine 0.6 mg kg-1 given to 21 normal and 20 anephric patients showed tubocurarine to be longer acting and considerably less predictable. This was particularly so in the anephric group, in which its action sometimes persisted after neostigmine had been given.

On the role of the baseline firing rate in determining the responsiveness of cingulate cortical neurons to iontophoretically applied substance P and acetylcholine

The relationship between baseline firing rate and the magnitude of excitatory responses to iontophoretically applied substance P (SP) and acetylcholine (ACh) was determined for neurons in the anterior cingulate cortex of the rat. Whereas the size of responses to ACh was positively correlated with the level of ongoing neuronal activity, no correlation, either positive or negative, could be demonstrated for responses to SP. It seems unlikely that the excitatory effects of SP in this brain area result from release of endogenous ACh.

The sensitivity of hippocampal pyramidal neurons to serotonin in vitro: effect of prolonged treatment with clorgyline or clomipramine

The sensitivity of hippocampal pyramidal neurons to the depressant action of serotonin was studied in hippocampal slices obtained from rats treated repetitively with clomipramine (10 mg/kg i.p.; 10 days or 4 weeks), with clorgyline 0.3 mg/kg s.c.; 10 days) or with the vehicle. Whereas clorgyline produced a very pronounced subsensitivity to serotonin, a moderate, non-significant reduction in sensitivity was observed with clomipramine. These electrophysiological findings are consistent with previous biochemical studies.

The hepatic extraction of gastric inhibitory polypeptide and insulin

The hepatic extractions of gastric inhibitory polypeptide (GIP) and insulin were determined using in vitro and in vivo methods to assess the role of the liver in GIP metabolism and the possible effect of GIP on the hepatic extraction of insulin. During in vitro studies using the isolated perfused rat liver, infusion of GIP (2000 pg/ml) alone and in combination with porcine insulin (200 microU/ml) resulted in negligible hepatic extraction of immunoreactive GIP (IR-GIP) in both fed and fasted animals during either physiologically euglycemic or hyperglycemic perfusions. Hepatic extraction of insulin, however, ranged from 26-36% in fasted animals and from 7-25% in fed animals. Hepatic extraction of insulin and net hepatic glucose appearance were minimally affected by GIP. In vivo studies in awake dogs were then performed, in which simultaneous portal and peripheral venous levels of IR-GIP, immunoreactive insulin (IRI), and glucose were assessed after intraduodenal glucose administration. The portal to peripheral (PORT/PERI) venous ratio of endogenous IRI and IR-GIP reflected the findings of the in vitro studies; the PORT/PERI ratio of IRI levels rose from a basal value of 1.9 +/- 0.3 to a peak of 3.7 +/- 0.9, while the PORT/PERI ratio of IR-GIP levels rose from a basal value of 1.0 +/- 0.1 to a peak of 1.4 +/- 0.2, then rapidly returned to 1.0. The in vivo data are consistent with a continuous hepatic extraction of 40-50% of the insulin entering the liver and a negligible hepatic extraction of IR-GIP. We conclude that hepatic extraction of GIP in vitro or in vivo is minimal. In addition, while the fed state of the animal before infusion can result in changes in the in vitro hepatic extraction of insulin, GIP does not mediate these changes.

Effect of prior administration of a non-depolarising muscle relaxant on the action of suxamethonium in the dog

The non-depolarising muscle relaxants alcuronium (0.1 mg kg-1), gallamine (1 mg kg-1) and pancuronium (0.06 mg kg-1) were administered to six dogs. At 50 per cent return of neuromuscular activity, as measured by the train-of-four technique, the depolarising muscle relaxant suxamethonium (0.3 mg kg-1) was injected intravenously. At 50 per cent return of neuromuscular activity, atropine and neostigmine were administered to reverse the neuromuscular block. The duration of action of suxamethonium was reduced by each of the non-depolarising muscle relaxants.

An increase in sensitivity of rat cingulate cortical neurones to substance P occurs following withdrawal of chronic administration of antidepressant drugs

The sensitivity of neurones in the cingulate cortex of the rat to iontophoretically applied substance P (SP) was tested one hour after a single dose of various antidepressant drugs and also 1 day following the termination of a chronic dosing schedule (14 once daily injections) of the same agents. One hour after a single injection of desipramine (DMI), chlorimipramine (CMI), trimipramine (TMI) or zimelidine ( ZIM ) (all at 10 mg kg-1 i.p.) there was no change in the mean size of excitatory responses to SP compared to those before the injection. There was a tendency towards a decrease in the TMI group. One day following the last of 14 consecutive daily injections (10 mg kg-1 i.p.) of the above agents there was a significant increase in the size of excitatory responses to SP compared to those in rats receiving daily saline injections. However, 14 days of treatment with DMI did not alter the responses to L-glutamate. Similar chronic dosing schedules with either diazepam (5 mg kg-1) or fluphenazine (5 mg kg-1) did not affect the responses to SP. Thus chronic but not acute administration of antidepressant drugs results in an increase in the sensitivity of neurones, in the cingulate cortex of the rat, to SP.

Treatment with rifampicin for Pneumocystis carinii pneumonia

The role of rifampicin in the treatment of serologically proved Pneumocystis carinii pneumonitis was reported recently from Poland (1). Serum antibody or antigen levels alone provide uncertain evidence as by four years of age two-thirds of normal children may have significant titres (2). We present the first case treated with rifampicin, and proven by open lung biopsy.

Histological evaluation of quantitative scintigraphy of the salivary glands in a primate model

To assess the accuracy with which quantitative scintigraphy reflects the true extent of parenchymal losses in diseased salivary glands, the parotid glands of vervet monkeys were unilaterally subjected to experimental injury and studied by scintigraphy and histomorphometry. The glandular 99Tcm pertechnetate uptake, relative to a standard dose, was expressed as the ratio of operated to unoperated sides. This was compared with the equivalent ratios of the weights of various salivary component tissues, morphometrically determined at necropsy. Our results suggest that uptake levels of 99Tcm pertechnetate are influenced predominantly by the mass of acinar rather than ductal tissue present. Furthermore, in comparisons between scans, because of the inherent variability in the results, quantitative scintigraphy is sensitive only to differences exceeding 25% of the gland mass.

Hepatic resection for metastatic cancer

One-year survival is infrequent in patients with metastatic cancer to the liver. This report includes 21 patients who underwent hepatic resection between 1974 and 1981. Operative procedures included one trisegmentectomy, 12 right hepatic lobectomies, two left hepatic lobectomies, two left lateral segmentectomies, and four wedge resections. Operative morbidity and mortality rates were 43% and 5%, respectively. Life-table analysis revealed an overall 7-year survival rate of 34%. The subset of patients (16) with colorectal adenocarcinoma had a 7-year survival rate of 29% after hepatic resection. In three patients with colorectal adenocarcinoma, frequent CEA determinations were made after surgery in order to calculate the serum half-life of CEA. The data fitted a biexponential function yielding two half-lives for CEA disappearance, 0.8 +/- 0.5 days and 25.9 +/- 10.3 days. We conclude that hepatic resection for isolated hepatic metastases can be performed with acceptable morbidity, low mortality, and prolongation of patient survival.

Insulin's effect on bile flow and lipid excretion during euglycemia and hypoglycemia

Mongrel dogs were prepared by cholecystectomy, ligation of the lesser pancreatic duct, and insertion of modified Thomas cannulas into the stomach and duodenum. When the dogs had recovered from surgery, studies were performed on them, conscious and unanesthetized after an overnight fast. The common bile duct was catheterized through the opened duodenal cannula for collection of hepatic bile. Bile flow was stabilized by the intravenous infusion of sodium taurocholate. After 2 hr of taurocholate infusion, insulin was added to the infusion and continued for the duration of the experiment. Glucose was administered intravenously during the first 120 min of insulin administration to maintain euglycemia; then the glucose was discontinued. The intravenous infusion of insulin during euglycemia maintained by glucose infusion caused a significant increase in bile flow and a decrease in bile salt concentration, but no change in bile salt output. There was a decrease in cholesterol concentration and output and in phospholipid concentration, but no significant change in phospholipid output. When glucose infusion was discontinued and hypoglycemia occurred, there was a further significant increase in bile flow, but no other change. These studies demonstrate that the choleretic action of insulin is not dependent upon hypoglycemia and that intravenously administered insulin may cause increased bile secretion without increase in serum glucagon concentration. These experiments also confirm that insulin choleresis may be associated with a decline in cholesterol output.

Effects of dibutyryl cyclic AMP and theophylline on biliary cholesterol secretion

Glucagon increases hepatocellular cAMP and decreases biliary cholesterol output. In these experiments, we examined the relation between cAMP and biliary cholesterol secretion. Bile flow and composition were measured in conscious dogs previously prepared by cholecystectomy, ligation of the lesser pancreatic duct, and placement of duodenal and gastric cannulae. Sodium taurocholate (500 mg/hr) was given intravenously to stabilize bile flow. After 2 hr of taurocholate infusion, dibutyryl cyclic AMP (160 mg kg-1 hr-1) or theophylline (20 mg kg-1 hr-1) was administered intravenously. Dibutyryl cAMP caused a decrease in both cholesterol concentration (242 +/- 25 micrograms/ml to 81 +/- 11 micrograms/ml) and cholesterol output (692 +/- 102 micrograms/15 min to 382 +/- 47 micrograms/15 min). Theophylline decreased cholesterol concentration (282 +/- 39 micrograms/ml to 221 +/- 21 micrograms/ml), but there was no significant change in cholesterol output. Bile flow increased significantly with both dibutyryl cAMP (2.8 +/- 0.2 ml/15 min to 4.9 +/- 0.2 ml/15 min) and theophylline (2.6 +/- 0.4 ml/15 min to 4.2 +/- 0.4 ml/15 min). In additional experiments, aminophylline (85% theophylline, 15% ethylenediamine) was administered intravenously (24.7 mg kg-1 hr-1). Aminophylline reduced cholesterol concentration (59 +/- 6 micrograms/ml to 36 +/- 5 micrograms/ml), but cholesterol output was stable. Bile flow increased significantly (3.7 +/- 0.2 ml/15 min to 6.5 +/- 0.4 ml/15 min). The mechanisms of these changes remain unknown. The effect of dibutyryl cAMP on biliary cholesterol secretion supports but does not prove the hypothesis that glucagon decreases biliary cholesterol output via the second messenger, cAMP.

Effect of prior administration of suxamethonium on non-depolarising muscle relaxants in the dog

The depolarising muscle relaxant suxamethonium (0.3 mg kg-1) was administered to six dogs. At 50 per cent return of the neuromuscular activity, as measured by the train-of-four technique, a non-depolarising muscle relaxant was administered. Three drugs, alcuronium (0.1 mg kg-1), gallamine (1.0 mg kg-1) and pancuronium (0.06 mg kg-1) were injected intravenously. At the 50 per cent return of neuromuscular activity, atropine and neostigmine were administered to reverse the neuromuscular block. The duration of action of the three non-depolarising relaxants was reduced by the prior administration of suxamethonium.

The mutagenic and cell transforming properties of shikimic acid and some of its bacterial and mammalian metabolites

Known and proposed metabolites of shikimic acid were synthesised, characterised and tested for genotoxic activity using the Salmonella/mammalian microsome mutagenicity test, the bacterial fluctuation mutagenicity test and the BHK 21 cell transformation test. Under the conditions used, none of these compounds showed any activity. However, shikimic acid itself was active in the BHK 21 cell transformation assay. It therefore seems unlikely that shikimic acid is a carcinogenic initiating agent, but it may act as a carcinogen-promoting agent in the bracken fern (Pteridium aquilinum).

Costodesis and contralateral rib release in the management of progressive scoliosis

This paper reports on 41 immature patients whose scoliosis was treated by fixation of ribs on the convexity. All had progressive scoliosis, the curve deteriorating at more than 10 degrees p.a., or the rib-vertebra angle difference being greater than 20 degrees. Of the 24 with infantile idiopathic scoliosis examined 5 years after operation, 10 maintained the improvement obtained at operation and in a further 19 the rate of deterioration had been slowed. Factors leading to a favourable outcome included: 1) An initial rib-vertebra angle difference of less than 30 degrees. 2) Success in achieving convex rib fusion. 3) The use of the operation in patients with infantile idiopathic scoliosis. There was a less favourable outcome in congenital and adolescent scoliosis. Spirometric volumes were diminished immediately after operation. Costodesis is therefore contraindicated in patients with precarious respiratory function.

Neural control of gastrointestinal motility: evidence for noncholinergic regulatory influences

Although it is well known that neural control of gastric motility occurs via sympathetic, parasympathetic, noncholinergic, and nonadrenergic fibers contained in the vagus nerve, the central sites of origin of these influences are largely unknown. Recent experiments in our laboratory indicate that noncholinergic neural pathways originating in the posterior hypothalamus can markedly influence gastric motility. At least 2 weeks prior to the experiment, mongrel dogs were surgically prepared with bipolar recording electrodes fixed to the serosal surface of the stomach. This prevented violation of the abdominal cavity on the day of testing. Experiments were performed with the animals under alpha-chloralose anesthesia (100 mg kg-1) in temperature-controlled settings. Under stereotactic guidance, bipolar stimulation of the posterior periventricular hypothalamus produced profound reproducible excitatory or inhibitory effects on gastric myoelectric and motor activity. Changes in the frequency and amplitude of pacesetter potentials (PPs) and in the incidence of action potentials associated with them were observed. Stimulation of various loci in 14 dogs resulted in a 71 +/- 7.5% increase in the incidence of action potentials associated with gastric PPs in "excitatory" areas (n = 7) and a 69.1 +/- 4% decrease in this ratio in "inhibitory" areas (n = 19). In general, more lateral stimulation produced greater inhibitory effects. Responses were frequency dependent, with a threshold greater than 25 Hz in most cases. Excitatory gastric responses to hypothalamic stimulation occurred despite full systemic atropinization (0.1 mg kg-1). The physiologic significance of these noncholinergic excitatory pathways influencing distal gastric motility and the neurotransmitters they employ are as yet unknown.

The action of anticonvulsant drugs on the firing of locus coeruleus neurons: selective, activating effect of carbamazepine

The action of various doses of intraperitoneally administered carbamazepine, ethosuximide, Na-valproate, phenobarbital and diphenylhydantoin on the neuronal firing rate of presumed noradrenergic neurons of the locus coeruleus was investigated in the anaesthetized rat. Carbamazepine was the only compound which produced a statistically significant, dose-dependent activation of these neurons. The other anticonvulsant drugs caused a small but non significant reduction in locus coeruleus cell firing. It is concluded that this brain nucleus is not a main target of anticonvulsant drugs.