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Biomedical subjects

J A Bell

Publications and source records attributed to J A Bell.

At least 163 records · Page 9Linked to original sources
PubMed1980

Noradrenergic action of amphetamine following degeneration of descending monoaminergic fibers in the spinal cord.

Amphetamine and methoxamine facilitated the flexor reflex in chronic spinal rats whose descending monoaminergic nerve endings were degenerated. Methoxamine, but not amphetamine, facilitated the flexor reflex in the chronic spinal rat 16-20 h after IV 6-hydroxydopamine treatment. These data indicate that amphetamine's spinal cord facilitative effects are mediated through two noradrenergic mechanisms. In the acute spinal rat, its facilitative effects in these experiments seem to be independent of the sympathetic nervous system and are probably dependent on the presence of the terminal axons of the long-descending noradrenergic pathways. In the chronic spinal rat, amphetamine's facilitative actions require the integrity of the sympathetic nervous system.

Amphetamine↗
PubMed1980

Radioimmunoassay of enkephalin: distribution in the cat spinal cord and the effect of superficial peroneal nerve stimulation.

A sensitive radioimmunoassay (RIA) for methionine-enkephalin (met-enk) was developed and used to measure enkephalins in different sagital sections of the L7-S1 spinal segment of the acute decerebrated spinal cat. Dorsal spinal sections were found to contain about three times higher concentrations of enkephalins than the ventral sections. Enkephalins in each section were also compared between cats which received supramaximal electrical stimulation of the superficial peroneal nerve (SP nerve) and those which received no stimulation. The SP nerve stimulation did not alter the enkephalin concentrations in all the sections examined. The results of this study support a hypothesis that enkephalinergic neurons are present in the dorsal horn of the cat spinal cord and provide evidence that enkephalin concentration in the spinal cord is not affected by SP nerve stimulation sufficient to evoke a C-fiber reflex in the acute decerebrated spinal cat.

Animals↗
PubMed1978

Chromosome analysis of bone marrow samples from country patients.

Co-operation by outside centres has made it possible to offer bone marrow chromosome analysis to patients living up to 1800 kilometres from the central cytogenetics laboratory. Diagnostic karyotypes have been obtained in 9 of 10 bone marrow specimens which were partially processed before being transported to the city laboratory for final analysis.

Australia↗
PubMed1978

Microforms: uses and potential.

A general overview of microform usage in libraries is provided, emphasizing the impact of conversion of print materials to microforms on library patrons and library staff members. Diagnostic techniques are analyzed to determine the adaptability of both collections and clientele. Problems concerning the standardization of hardware, selection of the proper microform formats, and the use of silver halide, diazo, or vesicular films are discussed.

Equipment and Supplies↗
PubMed1977

Responses of the flexor reflex to LSD, tryptamine, 5-hydroxytryptophan, methoxamine, and d-amphetamine in acute and chronic spinal rats.

The flexor reflex of acute (40-48 h after mid-thoracic spinal transection) and chronic (at least 2 months after transection) spinal rats was evoked by tetanic electrical stimulation of both hindfeet and recorded on a polygraph using a transducer connected to the left hindfoot. The flexor reflex in the chronic spinal rat was more responsive to electrical stimulation and to the actions of drugs studied than was the flexor reflex in the acute spinal rat. In chronic spinal rats, d-amphetamine, methoxamine, LSD, tryptamine, and 5-hydroxytryptophan (5-HTP) facilitated the flexor reflex and induced spontaneous movements. These facilitative effects were seen in acute spinal rats only when much larger i.p. doses of amphetamine, methoxamine, and LSD were used. Small i.v. doses of tryptamine also produced the facilitation. The facilitation caused by LSD and tryptamine, but not 5-HTP, in chronic spinal rats was antagonized by cyproheptadine. These observations suggest that chronic spinal rats were more sensitive to the drugs than acute spinal rats and support the hypothesis that the mode of action of LSD is similar to that of tryptamine but different from that of 5-HTP since cyproheptadine antagonized the facilitative effects of LSD and tryptamine but not those of 5-HTP.

5-Hydroxytryptophan↗
PubMed1977

The effect of the narcotic antagonists naloxone, naltrexone and nalorphine on spinal cord C-fiber reflexes evoked by electrical stimulation or radiant heat.

C-fiber reflexes were recorded from an S1 ventral root in the acute decerebrate low spinal cat following stimulation of the ipsilateral superficial peroneal nerve or application of radiant heat to the metacarpel footpad. Naloxone when administered i.v. increased the electrically evoked C-fiber reflex to 158% (+/- 23.8% S.E.M.) of control 10 min after administration; whereas, naltrexone, 0.0025 mg/kg, increased the C-fiber reflex to 206 +/- 26.1% (S.E.M.) of control. Naloxone in a dose of 0.050 mg/kg increased the radiant heat evoked ventral root reflext to 161 +/- 19.5% of control. Nalorphine, 1 mg/kg, facilitated the electrically evoked C-fiber reflex to 282 +/- 75% of control. These findings that naloxone and naltrexone facilitated these reflexes in doses too small to have non-specific excitatory effects and that nalorphine facilitated the C-fiber reflex at a dose level that is depressant to the flexor reflex in the chronic spinal dog are consistent with a hypothesis that these effects are due to antagonism of a naturally occurring opiate-like inhibitory substance.

Action Potentials↗
PubMed1976

Logical approach to lignocaine therapy.

Plasma lignocaine concentrations were measured during and after lignocaine infusions administered for suppressing ventricular dysrhythmias. Twenty-four patients with a primary diagnosis of acute myocardial infarction without gross circulatory disturbance received, after a bolus of lignocaine, either 4 mg/min for 30 minutes, 2 mg/min for two hours, then 1 mg/min thereafter or 1 mg/min throughout. The higher dose regimen produced continous therapeutic levels of lignocaine, which were achieved only after four hours by the lower dose. On the other hand, in patients who had undergone cardiac surgery and who had circulatory and heptic dysfunction the lower dose regimen achieved therapeutic levels early. The plasma half life was longer in the surgical group (P less than 0.02). The higher initial infusion rate is recommended for patients with acute myocardial infarction without gross circulatory impairment.

Adult↗
PubMed1976

Clinical, haemodynamic, and angiographic findings in Löffler's eosinophilic endocarditis.

Detailed haemodynamic and angiographic findings in Löffler's endocarditis are presented for the first time in a report of 3 cases of this rare disease. In 2 of the cases the right ventricular cavity was obliterated; in one of them this was shown by biopsy to be caused by organized thrombus. In the third case, there was progressive mitral regurgitation.

Blood Pressure↗
PubMed1976

The effect of L-tryptophan on spinal cord C-fiber reflexes.

C-fiber reflex were recorded from an ipsilateral S1 ventral root in the acute decerebrate spinal (T10) cat after stimulation of the superficial peroneal nerve. L-Tryptophan, infused in a dose of 150 mg/kg, increased the C-fiber reflex to 210% (S.E.M. +/- 30.1%) of control. This effect was antagonized by cyproheptadine, 0.5 mg/kg. L-Tryptophan increased the C-fiber reflex to 176% (S.E.M. +/- 13.0%) of control after p-chlorophenylalanine pretreatment. Pretreatment of the cats with the decarboxylase inhibitor alpha-methyldopa, 100 mg/kg, 30 minutes before infusion, antagonized the facilitatory effects of L-Tryptophan. L-Tryptophan, 150 mg/kg, had no effect on the monosynaptic or short latency polysynaptic reflexes. 5-Hydroxytryptophan, 20 mg/kg, had erratic effects on the C-fiber reflex producing both facilitation and depression which were not statistically significant. The recovery of tryptamine from brain perfusates, after perfusion of the anterior cerebellum and pons, with a modified Gaddum push-pull cannula, decreased across time. L-Tryptophan caused a slight increase in tryptamine release which was not statistically significant, whereas in cats pretreated with p-chlorophenyl alanine, a significant increase in tryptamine release was seen.

5-Hydroxytryptophan↗
PubMed1975

Human placental transfer of AH8165.

The human placental transfer of AH8165 (0times50times9 mg/kg) was studied in ten patients undergoing elective Caesarean section. There was no adverse effect on foetal movement attributable to placental transfer of the neuromuscular blocking drug. Bioassay of umbilical vein blood indicated that little AH8165 crossed the placenta. Studies using 3HAH8165 in two patients undergoing termination hysterectomy demonstrated transfer of only minute amounts of radioactivity to the foetus.

Apgar Score↗