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Biomedical subjects

D Taylor

Publications and source records attributed to D Taylor.

At least 523 records · Page 29Linked to original sources
PubMed1978

Electrophysiological analysis reinnervation of transplants in the anterior chamber of the eye by the autonomic ground plexus of the iris.

Fetal rat hippocampus, cerebellum, and heart were homologously transplanted to the anterior chamber of the eye of adult female recipients. After the grafts were allowed to mature in oculo, ingrowing adrenergic and cholinergic fibers from the iris were activated by changing the illumination of the retina. Electrophysiological recordings from all three types of transplants showed changes similar to those reported for effects of adrenergic and and cholinergic inputs in situ. Pharmacological studies with the transplants indicated that these electrophysiological changes were caused by activation of local muscarinic cholinergic and beta-adrenergic synapses. These data suggest that the intraocular graft is able to induce functional adrenergic and cholinergic inputs from the ground plexus of the iris and support the hypothesis that target organ influences play an important role in synaptogenesis.

Action Potentials↗
PubMed1978

The uptake of 6-methoxy-1,2,3,4-tetrahydro-beta-carboline and its effect on 5-hydroxytryptamine uptake and release in blood platelets.

The uptake of 6-methoxy-1,2,3,4-tetrahydro-beta-carboline (6-MeOTHBC, 5-methoxytryptoline) by rabbit blood platelets was studied by using 3H-labelled compound. A high rate active uptake (Km 6.6 micron), which was inhibited by 5-hydroxytryptamine (5-HT) and cinnanserine, and a slow rate uptake, not inhibited by 5-HT were observed. The intracellular distribution of 3H-6-MeOTHBC in platelets clearly differed from that of 14C-5-HT. 6-MeOTHBC also competitively inhibited the high-rate active (but not the slow passive) uptake of 14C-5-HT, being more active than 5-HT itself. The spontaneous release of the newly taken-up 14C-5-HT from platelets was increased only with high concentrations of 6-MeOTHBC.

Animals↗
PubMed1978

Chairside language.

Explore the source record for details and available documents.

Anesthesia, Local↗
PubMed1978

Major pharmacological effects of 6-methoxytetrahydro-beta-carboline, a drug elevating the tissue 5-hydroxytryptamine level.

Major pharmacological effects of 6-methoxy-1,2,3,4-tetrahydro-beta-carboline (6-methoxytryptoline, 6-MeOTHBC) are described. It seemed to have a weak effect of its own on 5-HT-receptors. It is concluded that most of the effects, like the increase of rectal temperature after peripheral administration and decrease and then increase after intrahypothalamic application as well as the antagonism of the group toxicity of amphetamine without effect on norepinephrine toxicity or barbiturate sleeping time, can result from the increase of tissue 5-HT-concentration and/or inhibition of 5-HT-uptake.

Acute Disease↗
PubMed1978

Lead blockade of norepinephrine-induced inhibition of cerebellar Purkinje neurons.

Biochemical studies showing that lead (Pb++) inhibits cerebellar adenylate cyclase (IC50 = 2 micrometer) prompted us to test the effects of this cation on the depression of spontaneous discharge of Purkinje (P) cells produced by iontophoresis of norepinephrine (NE). Previous studies have suggested that the effects of NE on P cell discharge may be mediated by activation of a NE-sensitive adenylate cyclase. Iontophoresis of Pb++ in situ, and in cerebellar transplants in oculo, reliably antagonized NE responses in over 80% of the P cells studied in both preparations. Blockade was readily seen at iontophoretic currents of 5 to 10 nA. Superfusion of PB++ (5--10 micrometer) into the anterior eye chamber also antagonized NE responses in P neurons of the transplant. Spontaneous discharge rate was either unaffected or slightly elevated at Pb++ levels that almost completely blocked NE. Barium, a heavy metal which does not inhibit adenylate cyclase in vitro, did not block NE effects. Stimulation of parallel fibers or iontophoresis of acetylcholine excited P cells. No antagonism was seen, however, between Pb++ and these acetylcholine or parallel fiber excitations. These results raise the possibility that blockade of brain catecholamine receptors may partially underlie the central nervous system toxicity seen with lead administration.

Animals↗
PubMed1978

Comparison of inhibition of monoamine uptake by cocaine, methylphenidate and amphetamine.

Amphetamine and methylphenidate both inhibited the uptake of 3H-norepinephrine (NE) and 3H-dopamine (DA) although the activity (as measured by I50 and Ki values) of d-amphetamine was lower with respect to uptake of the two catecholamines in synaptosomes from thalamus-hypothalamus and and striatum. Cocaine was a much stonger inhibitor of 3H-5-hydroxytryptamine (5-HT) uptake in septum-caudate synaptosomes than amphetamine or methylphenidate. The I50 values were 70, 118 and 570 micron for cocaine, methylphenidate and d-amphetamine, respectively. The results of the present study suggested that a serotonergic system may be involved in the stimulant properties of cocaine. It may also explain certain differences in pharmacological activities between cocaine and the other two stimulants as described in the literature.

Animals↗
PubMed1977

Survival after cardiac arrest in hospital.

A 10-year experience of cardiac arrests in a district general hospital is reviewed. 1063 arrests in the general areas of the hospital were studied, excluding the coronary and intensive care units. In 718 (67-5%) initial resuscitation was unsuccessful; in 252 (23-7%) the patient died later in hospital, 93 patients (8-7%) were discharged alive. After discharge from hospital there was a progressive annual mortality of about 7% for the first five years, but thereafter no patient died. Significant incapacity after discharge was also unusual. The probability of successful resuscitation was greater in patients with primary cardiac disease (11-8% survival), drug overdose (22-2% survival), or undergoing anaesthesia (20-0% survival). The success-rate was significantly greater in the accident and emergency department (7-9%) than on the wards (2-1%), but this difference was due entirely to the more successful resuscitation of patients with myocardial infarction in the accident and emergency department. Within each diagnostic category the survival-rate was independent of the age of the patient. Prolonged survival after resuscitation but ending in death before discharge was unusual.

Adult↗
PubMed1977

Neurochemical effects of cocaine following acute and repeated injection.

Following repeated injection in the rat, cocaine decreased the concentration of serotonin in the septum-caudate and increased the metabolism of hypothalamic norepinephrine and also striatal dopamine to a lesser extent. Furthermore, cocaine significantly decreased the activity of the rate-limiting enzyme, tryptophan hydroxylase. In a comparative study d-amphetamine and methylphenidate were found to exert an effect opposite to cocaine in the activation of tryptophan hydroxylase. These findings indicate that cocaine may lower central serotonin function by decreasing its availability for neural transmission. This could account for the stimulation of locomotor activity observed after cocaine administration.

Animals↗
PubMed1977

Asylums revisited.

The authors revisited Erving Goffman's Asylum (Saint Elizabeths Hospital) and found both the "institutionalization" and "secondary adjustment" phenomena he described 20 years ago. However, they question whether secondary adjustments necessarily follows institutionalization. They also express doubt that institutionalization should be condemned automatically and suggest that it may in fact be the approach of choice for some patients.

Activities of Daily Living↗
PubMed1977

Experimental infection of cats with the liver fluke Platynosomum concinnum,.

The severity of Platynosomum concinnum infection in cats experimentally infected with 125 flukes (small dose) and 1,000 flukes (large dose) was determined by monitoring clinical signs and hematologic, serum biochemical, and pathologic changes during the infection. All cats (8/8) with a small fluke burden and 3 of 8 cats with a large burden remained clinically asymptomatic, whereas 60% of the cats given large doses had mild signs of inappetence and lethargy. Eosinophilia, peaking 4 to 5 months after infection, was present in all parasitized cats. During the early stages of platynosomiasis, a transient but substantial increase in aspartate aminotransferase and alanine aminotransferase activities was observed in cats given small and large doses. These observations agreed with gross and histopathologic observations, which included enlargement of the gallbladder and biliary ducts, with leukocyte infiltration, adenomatous hyperplasia, and fibrosis of the ductal areas.

Alanine Transaminase↗
PubMed1976

Modification of diamine oxidase activity in vitro by metabolites of asparagine and differences in asparagine decarboxylation in normal and virus-transformed baby hamster kidney cells.

1. The oxidation of putrescine in vitro by pig kidney diamine oxidase (EC 1.4.3.6) was increased in the presence of 2-oxosuccinamic acid and malonamic acid. 2. It was inhibited by 3-aminopropionamide, oxaloacetate and pyruvate. 3. 2-Oxosuccinamate was derived from asparagine in virus-transformed baby hamster kidney (BHK) cells growing in tissue culture. 4. Asparagine was decarboxylated more efficiently by transformed than by normal BHK cells. 5. In BHK cells transformed by polyoma virus (Py BHK), 2-oxosuccinamate is the most likely immediate precursor of the 14CO2 arising from [U-14C]asparagine, and there was some evidence for its formation in an asparagine-dependent clone of BHK cells before and after their transformation by hamster sarcoma virus (respectively Asn- and HSV Asn-). 6. The relationship between 2-oxosuccinamate and pyruvate and the possible roles of these two substances in controlling cellular diamine oxidase activity are discussed.

Alanine↗