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Biomedical subjects

H Hall

Publications and source records attributed to H Hall.

At least 199 records · Page 11Linked to original sources
PubMed1981

Vocational disability and rehabilitation in multiple sclerosis.

Multiple sclerosis represents a significant cause of vocational disability among young and middle age adults. As a group, M.S. patients are frequently well educated, highly trained and possess intact families but have had to leave their former occupations. While many unemployed M.S. patients are willing and able to work, they are not now receiving the vocational rehabilitation services they need to reenter the work force. Physicians frequently see M.S. patients, but they do not often refer those patients for vocational rehabilitation services. Unemployment associated with multiple sclerosis is a significant social complication of the disease. While the physician cannot cure or halt the progress of the disease, he or she can assist the M.S. patient in obtaining the specialized help necessary to re-enter the job market.

Adolescent↗
PubMed1981

The pharmacology of zimelidine: a 5-HT selective reuptake inhibitor.

Zimelidine (ZIM) and its main active metabolite norzimelidine (NZIM) have been shown to preferentially inhibit 5-hydroxytryptamine (5-HT) neuronal uptake both in vitro and in vivo while having much less effect on noradrenaline (NA) uptake. ZIM in vivo blocked the 5-HT uptake mechanism in the cerebral cortex, hippocampus, striatum, hypothalamus and spinal cord, thus indicating effects on both the ascending and descending 5-HT pathways. ZIM is devoid of a 5-HT releasing action, MAO-inhibitory properties and effects on dopamine (DA) uptake. ZIM failed to reduce NA turnover even in high doses, but markedly reduced 5-HT turnover in very low doses in the rat. ZIM also enhanced 5-HT mediated behaviours in mice in doses related to the inhibition of 5-HT uptake. In contrast to amitriptyline (AMI) and mianserin (MIAN), ZIM only in extremely high doses displayed a 5-HT receptor blocking action in vitro and failed to block 5-HT mediated behaviour. ZIM was practically devoid of action on histamine H1 and H2 receptors, and had also a neglible action on noradrenergic alpha 1- and alpha 2-receptors, and on beta-receptors. Unlike the tricyclic antidepressants (TAD's) ZIM had a negligible action on muscarinic receptors and failed to affect cholinergic induced activity. Long-term treatment with ZIM did not result in any attenuation of the 5-HT uptake blocking potency or the reduction of 5-HT turnover. This long-term treatment slightly reduced the number of beta-receptors in the brain. However, repeated ZIM-treatment induced a new 5-HT receptor binding site characterized by a low affinity and with a high number of binding sites and decreased the number of high affinity 5-HT receptor binding sites. Unlike the TAD's zimelidine failed to block the action of reserpine. Metabolic and behavioural interactions studies in mice showed that ZIM was devoid of any significant interactions with ethanol, barbiturates and benzodiazepines. It is concluded that ZIM markedly differs from both the TAD's and new antidepressants such as mianserin and nomifensine. ZIM seems preferentially to effect the presynaptic 5-HT reuptake mechanism while having a negligible action on noradrenergic, 5-HT, acetylcholine and histamine receptors in the brain.

Animals↗
PubMed1981

Sedative/anxiolytic effects of antidepressants in animals.

The sedative effects of several different structural types of antidepressants were investigated in mice. Six different models of sedation were used and the results were averaged. The rank order of sedative potency was: amitriptyline greater than mianserin greater than maprotiline greater than imipramine greater than desipramine greater than clomipramine greater than alaproclate greater than zimelidine greater than norzimelidine. Sedative potency of the antidepressants was found to be significantly correlated with their affinity for four different brain amine receptors. The rank order of correlation of sedation with receptor affinity was: histamine (H1) greater than serotonergic greater than muscarinic greater than alpha 1-adrenergic. These findings appear to be associated with clinical side effects observed during treatment with antidepressants. While scant literature is available concerning specific anxiolytic effects of antidepressants, pharmacological evidence for the role of central 5-HT systems in the anxiolytic effect is plentiful. Our preliminary findings show a marked antagonism of isolation-induced aggression by low doses of the specific 5-HT uptake inhibitor, zimelidine, and the 5-HT releasing agent, p-chloramphetamine, thus supporting the hypothetical importance of 5-HT in the pharmacology of anxiolytic agents.

Aggression↗
PubMed1980

Central monoamine synapses as sites of action for ergot drugs.

The acute and subacute effects of ergot drugs on central monoaminergic mechanisms were studied in the rat. The most significant findings are: 1. After acute treatment, lergotrile and bromocriptine were found to block apomorphine-induced locomotion and rearing, suggesting that these two ergot drugs can block postsynaptic DA receptors within the nucleus accumbens. 2. Several ergot drugs were shown to have high affinity for some 3H-ADTN binding sites. Earlier studies indicate that 3H-ADTN appears to label postsynaptic dopamine receptors located on nerve cells in the striatum. These ergot-sensitive 3H-ADTN binding sites appear not to be linked to the adenylate cyclase system. In addition, bromocriptine, unlike CM 29-712, was found to have a high affinity for 3H-spiperone binding sites in the striatum. 3. Bromocriptine and CM 29-712 increased norepinephrine turnover in periventricular and paraventricular hypothalamic areas, suggesting a blockade of norepinephrine receptors. CM 29-712 also increased DA turnover in the medial palisade zone of the median eminence. 4. Some ergot drugs also had affinity for 5-HT receptor binding sites, possibly reflecting a 5-HT agonistic action in some areas, as shown in behavioral studies. 5. Apomorphine and bromocriptine displaced in vivo 3H-spiperone binding in the hypothalamus, septal area, and substantia nigra, but not in the striatum. 6. Subacute treatment with bromocriptin and CM 29-712 were found to produce two types of changes in behavior: The apomorphine-induced locomotion was enhanced while the chewing and licking activity (stereotypies) was reduced. These behavioral changes may be associated with an increased affinity in the 3H-ADTN binding sites in the striatum. This treatment also produced persistent increases of DA turnover in the tuberculum olfactorium but not in striatum.

5-Hydroxytryptophan↗
PubMed1980

Effects of chronic treatment with l-sulpiride and haloperidol on central monoaminergic mechanisms.

Chronic treatment with l-sulpiride (20 mg/kg, twice daily) and haloperidol (0.2 mg/kg, twice daily) for 2 weeks produced behavioral signs of DA receptor supersensitivity in both the striatum and the nucleus accumbens-tuberculum olfactorium region. Thus, 48 hr after treatment apomorphine-induced locomotion, total activity, and rearing activity was significantly enhanced. These behavioral results were correlated with 10% increases in the number of binding sites for the DA agonist 3H-ADTN and the DA antagonist 3H-spiperone in striatum, but the latter sites appeared to be markedly increased in number in the subcortical limbic region. A marked loss of stereoselectivity was demonstrated in the 3H-ADTN binding site, a change that could also in part be involved in producing the signs of enhancement of DA effector mechanisms observed. A corresponding loss of stereoselectivity was not observed in the 3H-spiperone binding site to which, instead, the (+)-butaclamol had an increased affinity. Haloperidol, but not l-sulpiride, in the doses used produced a further enhancement of degeneration-induced supersensitivity at DA receptor sites.

5-Hydroxytryptophan↗
PubMed1979

Failed lumbar disc surgery and repeat surgery following industrial injuries.

One hundred and seventy-nine of the compensation patients in this study who had one low-back operation had to have repeat back surgery. One hundred and three Workmen's Compensation Board patients who were reoperated on by a number of surgeons in the Toronto area were independently reviewed with one to two years of follow-up. Many had residual back pain, limited lumbar movement, presisting nerve-root deficits, and psychological disturbances. Forty per cent of the second operations were successful. Subsequent operations yielded progressively poorer results and made more patients worse than better. Operations were frequently undertaken without clear indications or evidence of correctable organic lesions. The results of repeat operations were better when the preceding operation had given more than six months' relief, when sciatica overshadowed back pain, and when a definite recurrent disc herniation was found. Scarring and neurolysis, previous infection, repair of a pseudarthrosis, and adverse psychological factors precluded a good result. Careful patient selection based on total evaluation of the disability including psychological assessment, accurate localization of the lesion by detailed investigation, and, most important, a logical sequence of decisions based on clear, objective criteria are prerequisites for this complex and demanding surgery. Caution and restraint are required when contemplating repeat back surgery.

Accidents, Occupational↗
PubMed1977

Immunochemical comparisons between a low molecular weight adenohypophyseal constituent and the gonadotrophins.

A biologically active peptide (called sperm-releasing substance, abbreviated SRS) with a molecular weight of about 5000, prepared from bovine adenohypophyses, has been compared with the known adenohypophyseal glycoprotein hormones using immunological methods. By means of immunofluorescence it can be seen that antisera against SRS have an affinity for the gonadotrophic cells in the anterior pituitary. Using complement fixation assay and immunodiffusion, no similarity between SRS and FSH can be found, while there are great resemblances between the reactions of LH and those of SRS. From the radioimmunoassay studies, it can be seen that the alpha-subunit of LH reacts in the same way as SRS in the different systems. However, using immunofluorescence, the antiserum against SRS has an affinity for the gonadotrophic cells only, like anti-LHbeta, and not for the thyrotrophic cells, as has anti-LHalpha. The reasons for these different results are discussed.

Animals↗
PubMed1977

A new textbook.

Explore the source record for details and available documents.

Books↗
PubMed1975

Textbooks -- a new approach.

A new approach to medical textbooks has been applied by a team comprising a publisher, educationalist, and subject specialist. The binding of the book can be opened so that additional material can be added and the pages rearranged. Illustrations are printed on separate sheets so as to be available for study at any point in the text. An interdisciplinary approach has been adopted throughout and each section of the book examines the subject from a different viewpoint, for example, a disease, a clinical presentation, or an approach to therapy. An important feature is the separation of core material from additional material. Layout and design have been used to facilitate learning and to make possible the use of the book for reference and revision.

Bookbinding↗
PubMed1975

Distribution of an adenohypophysial constituent in the body. I. Wholebody autoradiographical studies in the mouse.

A peptide with a molecular weight of about 5 000 has previously been shown to affect the output of semen in frogs and probably also in mammals. This sperm-releasing substance is not part of any known gonadotropic hormone. The distribution of this substance has been investigated using whole-body autoradiography. Radioactive material is incorporated into the epididymis, the adenohypophysis and probably also into the ovary.

Animals↗