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Biomedical subjects

E S Johnson

Publications and source records attributed to E S Johnson.

At least 109 records · Page 6Linked to original sources
PubMed1984

Ergotamine toxicity and serum concentrations of ergotamine in migraine patients.

Twenty-five migraine patients (9 males and 16 females) aged 22-71 who had used between 7 and 60 mg ergotamine tartrate per week for 1.5-30 y volunteered to participate in the study. Side-effects attributable to ergotamine were wide ranging and included daily headache and pain in the limbs. Wide variation in sensitivity to the drug was observed and side-effects were not always proportional to the dose of ergotamine. Random serum ergotamine concentrations were estimated in all patients and 10 of them volunteered to take a 2 mg oral challenge of ergotamine tartrate. Ergotamine was not detected in 44% of the random estimations even though all patients exhibited clinical signs of ergotamine tartrate overdose. The remaining 56% estimations all showed low drug concentrations. After the 2 mg oral challenge of ergotamine in the 10 patients, significantly higher concentrations, but still within therapeutic range, were detected in the sera when compared with mean concentrations achieved after the same oral dose of the drug in healthy, non-migrainous subjects.

Adult↗
PubMed1984

Rhabdoneuroglial heterotopias of the pontine leptomeninges in trisomy 13.

An unusual heterotopia of striated skeletal muscle and glial tissue occurred in the pontine meninges of a stillborn male showing feature of trisomy 13 and an Arnold-Chiari malformation. In two other reports of this type of heterotopia, the location and association with trisomy 13 has been the same. An error in tissue differentiation at the pontine flexure is suggested to account for this relationship.

Adult↗
PubMed1982

Neonatal-onset adrenoleukodystrophy in a girl.

A 4-year 11-month-old girl developed cerebral degeneration with onset in the neonatal period. Postmortem examination showed gross, microscopic, ultrastructural, and biochemical changes identical to those associated with adrenoleukodystrophy (ALD), a sex-linked disorder of boys beginning in the first decade of life. Cytoplasmic inclusions ultrastructurally identical to those in brains and adrenal glands of ALD patients were present not only in this girl's adrenal glands and brain but also in reticuloendothelial cells of the liver, lymph node, spleen, thymus, and hepatic lysosomes. Thin-layer and gas-liquid chromatographic analysis of cerebral tissues demonstrated abnormal long-chain fatty acids in the cholesterol ester fraction, identical to those present in affected tissues of males with ALD. The documentation of abnormal long-chain fatty acids in cerebral tissues of a female patient supports the concept that infantile-onset ALD is a clinically and pathologically distinctive entity characterized by prominent visceral storage abnormalities and occurrence in both sexes. These findings also suggest that ALD and related entities are either phenotypic variants of a specific enzyme deficiency or separate disease resulting from different mutations in a common metabolic pathway.

Adrenal Glands↗
PubMed1982

Costs of providing dental services to adult mentally retarded: a preliminary report.

This study reports on the hourly costs of providing comprehensive dental services to mentally retarded adults in a hospital-based group dental practice. The analysis indicated average total hourly costs of $56.11 for dentist-provided services an $22.25 for dental hygienist-provided services. When compared to the revenues available for program maintenance, a net hourly deficit of $18.82 per dentist hour and $9.89 per dental hygienist hour resulted. The implications of this operating loss on the continued care of this patient population are discussed.

Adolescent↗
PubMed1981

Evidence for a "dying-back" gliopathy in demyelinating disease.

Recurrent demyelination was produced in mice by Cuprizone administration. During the second course of Cuprizone, the animals showed greater resistance to the toxin and demyelination occurred slowly and was complete only after prolonged periods. The earliest changes in oligodendrocytes occurred in the most distal processes, the inner cytoplasmic tongues, which showed degenerative changes 3 to 4 weeks before degeneration of the oligodendrocyte cell bodies or demyelination occurred. The results show for the first time that in demyelinating disease, a "dying-back" process similar to that described in axonal disease can affect the oligodendrocyte.

Animals↗
PubMed1981

The demonstration of recurrent demyelination and remyelination of axons in the central nervous system.

A model for studying recurrent demyelination and remyelination in the central nervous system was developed by means of repeated administration of Cuprizone to mice. In contrast to the demyelination seen during the first course of Cuprizone, the recurrent demyelination was markedly protracted, displayed features of a "dying-back" gliopathy, and resulted in a greatly reduced inflammatory and glial reaction. The repeat remyelination also occurred at a slower tempo, varied markedly in completeness, and was associated with a diminished regeneration of oligodendrocytes. These results demonstrated that axons of the central nervous system in this model can be recurrently remyelinated if oligodendrocytes are available, that regeneration of oligodendrocytes is dependent upon the tissue reaction to demyelination, and that remyelinated axons are not more susceptible to demyelination than normal ones.

Animals↗
PubMed1981

Epidural block for treatment of renal colic during pregnancy.

This report documents for the first time the application of continuous segmental epidural block (T11 to L2) to treat renal colic complicating pregnancy. The block was maintained for 16 hours and the pain did not recur. Advantages for the mother, and possibly for the foetus, are considered. The published experience of others using this technique in nonpregnant patients is reviewed.

Adult↗
PubMed1980

Inhibition of electrically induced twitch responses of the guinea-pig ileum by histamine.

Inhibition of twitch responses of the guinea-pig isolated ileum to low frequency electric stimulation (0.2 Hz) followed the interpolation of a dose of histamine left in contact for 30 sec. This post-histamine inhibition, which was dose related, was not affected by mepyramine or cimetidine and thus was not brought about by an action on known histamine receptors. Histamine also reduced the height of contractions caused by exogenous acetylcholine (ACh) and this inhibition was quantitatively similar to the degree of post-histamine inhibition of twitch recorded at corresponding times following the removal of histamine by overflow. It therefore seems likely that histamine-induced inhibition of twitch is caused by desensitisation of the postsynaptic membrane to endogenous ACh released during transmural stimulation.

Acetylcholine↗
PubMed1980

Modulatory action on the twitch responses of the guinea-pig ileum of endogenous substances released by high frequency electrical stimulation.

Inhibition of twitch responses of the guinea-pig isolated ileum to low frequency electrical stimulation (0.2 Hz) followed the interpolation of a 30 sec period of high frequency electrical stimulation (HFS; 7.5 and 10 Hz). Indomethacin (1-2.5 microM) potentiated this inhibition of twitch following HFS at 10 Hz but not 7.5 Hz. The addition of naloxone (1 microM) markedly antagonised the post-HFS inhibition caused by both frequencies of stimulation. Metoclopramide (10 microM), which was shown to have selective antagonist properties on prejunctional ACh receptors (pA2 = 5.1), reduced the post-HFS inhibition of twitch when added with the other antagonists and shortened the time course of recovery. The inhibition of twitch responses following the interpolation of ACh (680 nM) for 30 sec was unaffected by indomethacin and naloxone but was markedly antagonised by metoclopramide. Thus, HFS release in addition to ACh, prostaglandins which potentiate the twitch response and an opiate receptor ligand which inhibits transmitter release. The use of guanethidine (10 microM) in the present experiments precluded the involvement of noradrenaline.

Acetylcholine↗
PubMed1980

The effects of some dopamine antagonists on cholinergic mechanisms in the guinea-pig ileum.

1. Activation of prejunctional muscarinic and opiate receptors on cholinergic neurones of the guinea-pig ileum by acetylcholine (ACh) or morphine was seen as an inhibition of twitch responses to transmural electrical stimulation. These inhibitory responses were antagonised by metoclopramide and DL308-IT but no other antagonist used blocked the morphine responses apart from sulpiride in very high concentrations (100 muM and above). 2 Prejunctional and postjunctional responses to ACh on the guinea-pig ileum were measured in the presence of increasing concentrations of some muscarinic and dopamine antagonists. Atropine, hyoscine, chlorpromazine, cis-flupenthixol and thioridazine showed no selectivity in their antagonism of either response to ACh. Benzhexol selectivity antagonised the postjunctional response whereas metoclopramide and DL308-IT showed greater selectivity for the prejunctional effect which they antagonised competitively. Sulpiride, a compound chemically related to metoclopramide, blocked neither the prejunctional nor postjunctional ACh responses. Clozapine antagonised the postjunctional ACh responses whilst apparently potentiating the prejunctional inhibition by ACh. 3 It was concluded that pharmacological differences may exist between prejunctional and postjunctional muscarinic receptors for ACh and that the antipsychotic actions of dopamine antagonists are unlikely to involve blockade of prejunctional ACh or opiate receptors.

Acetylcholine↗