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Biomedical subjects

J W Lance

Publications and source records attributed to J W Lance.

At least 55 records · Page 3Linked to original sources
PubMed1991

5-Hydroxytryptamine and its role in migraine.

Platelet 5-hydroxytryptamine (5-HT) is diminished during migraine headache and the injection of reserpine, which releases 5-HT from body stores, induces a typical headache in migrainous subjects. The intravenous injection of 5-HT relieves established migraine headache, but causes side-effects of nausea, faintness, paraesthesia and dyspnoea. The 5-HT1-like agonist sumatriptan exerts the beneficial effects of 5-HT with minimal side-effects. Receptors for 5-HT are present in cranial arteries and are also widely distributed in the central nervous system, where they play a role in the neural control of the cranial circulation and endogenous pain control system. The pathophysiology of migraine involves interaction between these central pathways and cranial blood vessels. It is probable that many prophylactic agents exert their action by central 5-HT2 antagonism, whereas termination of an established attack of migraine depends upon constriction of cranial vessels mediated by 5-HT1 receptors.

Humans↗
PubMed1990

[Physiopathology of migraine].

In those subjects genetically susceptible to migraine, biological rhythms or excessive afferent stimulation trigger an episodic neurovascular reaction with focal neurological symptoms, headache and nausea as its most common manifestations. Mood changes and a craving for sweet foods point to a preliminary hypothalamic disturbance. The referral of ice-cream headache and ice-pick pains to the habitual site of migraine headache (even in the intervals between attacks) indicate defective control of trigeminal pathways. Laboratory experiments have demonstrated that projections from the brainstem, releasing monoamines and peptides as transmitter agents, can mimic the vascular changes of migraine. Serotonin released from platelets may sensitize vessels to respond to distension by generating pain-producing afferent discharges. Central depletion of monoamines can accentuate the perception of pain by reducing the efficacy of the endogenous pain control system. The intravenous injection of serotonin relieves migraine headache but produces side-effects. A new drug, sumatriptan, acting on a subtype of serotonin receptors, the 5HT1-like receptor, is undergoing clinical trial for the relief of acute attacks of migraine. Antagonist of the 5HT2 receptor are beneficial in interval therapy for the prevention of migraine. Increased knowledge of physiological mechanisms and neurotransmitters that can mediate the various components of the migraine attack opens the way for improvements in pharmacotherapy.

Humans↗
PubMed1990

Temporal arteritis. A preventable cause of blindness.

Temporal arteritis is an uncommon condition but must be recognised early if complications such as blindness are to be avoided. The onset of daily headache or systemic disturbance with muscle and joint pains in patients over the age of 50 years should arouse suspicion. The ESR is usually greater than 40 mm an hour, but it is advisable to proceed to temporal artery biopsy if the story is typical even though initially the ESR may be normal. Histological confirmation is desirable because steroid therapy may have to continue for several years.

Adult↗
PubMed1989

Partial seizures with visual disturbance treated by radiotherapy of cavernous hemangioma.

A man aged 26 years had been subject to frequent transient episodes of left homonymous hemianopia, initially accompanied by visual hallucinations and left miosis, since the age of 8 years. These partial seizures recurred 3 to 30 times each month in spite of treatment with anticonvulsant medication. The causative lesion, which had escaped detection by cerebral angiography and repeated computed tomographic scanning, was shown by magnetic resonance imaging to be a small cavernous hemangioma in the right occipital lobe. This was treated by a course of fine-beam radiotherapy directed to the lesion. After treatment the partial attacks ceased, although one nocturnal clonic seizure occurred 12 months after radiotherapy and 6 weeks after stopping all anticonvulsant medication.

Adult↗
PubMed1989

Stimulation of brainstem nuclei in the cat: effect on neuronal activity in the primary visual cortex of relevance to cerebral blood flow and migraine.

The electrical activity of single neurons was recorded in the primary visual cortex of anesthetized cats in order to test the hypothesis that changes in their activity might be the cause of the changes in blood flow seen after stimulation of the brainstem and in migraine. Discharge evoked by optic radiation stimulation was facilitated by conditioning stimulation (6 pulses over 24 msec) of the locus coeruleus (LC), whereas no consistent effect was exerted on resting discharge. No clear difference could be demonstrated between the effect on resting discharge of short-duration stimulation of the LC, midbrain reticular formation and dorsal raphe nucleus (DRN). Stimulation of these structures at 5/sec for 10 sec was also studied to ascertain whether long-term changes in neuronal activity could be produced, and to indicate whether changes in cerebral blood flow previously described with these parameters of stimulation were secondary to alterations in metabolic demand due to increased or decreased bulk neuronal activity. The vast majority of single neurons were unaltered by these parameters of stimulation, suggesting that cortical blood flow changes following LC and DRN stimulation are due to a direct action on the cortical microcirculation.

Animals↗
PubMed1989

Massive benign thymoma presenting as ocular myasthenia.

A case of ocular myasthenia was found to be associated with a massive benign thymoma and responded to its removal. This is an exception to the generalisation that larger tumours of the thymus gland are more likely to be malignant and that thymectomy is not the treatment of choice for ocular myasthenia.

Adult↗
PubMed1989

5-Hydroxytryptamine and its putative aetiological involvement in migraine.

5-Hydroxytryptamine (5-HT, serotonin) is thought to play a part in the pathophysiology of migraine because platelet content of 5-HT in cubital and external jugular veins is reduced during migraine headache. Moreover migraine headache is precipitated by intramuscular injection of reserpine, which releases 5-HT from body stores, is relieved by the intravenous infusion of serotonin, and is prevented by the regular administration of medications that act on 5-HT receptors. Whether the peripheral action of 5-HT on cerebral and extracranial vessels or its central action as a neurotransmitter involved in bulbocortical and pain control pathways is of greater importance in the mechanism of migraine remains an open question. Increasing knowledge of the varieties of 5-HT receptor and the development of pharmacological agents that act specifically on certain receptors should give greater insight into the cause of migraine and increase the efficacy of treatment.

Brain↗
PubMed1989

Clinicopathological correlation in a case of painful ophthalmoplegia: Tolosa-Hunt syndrome.

A case of painful ophthalmoplegia due to idiopathic granulomatous involvement of the superior orbital fissure (Tolosa-Hunt syndrome) is described. The clinical features of recurrent pain, ocular motor nerve palsies and proptosis correlated well with the eventual demonstration of an enhancing mass in the region of the cavernous sinus. Removal of the lesion led to a resolution of the clinical picture and demonstration of a non-caseating granuloma with no other detectable cause. The original observation of Tolosa was thus re-affirmed.

Cavernous Sinus↗
PubMed1989

Plasma serotonin in patients with chronic tension headaches.

Previous reports have suggested that platelet level of serotonin in chronic tension headache (CTH) is lower than in normal control subjects, and that there is continuous activation of platelets both in migraine and in CTH. In this study we compared platelet serotonin concentration in 95 patients with CTH, 166 patients with migraine and 35 normal control subjects. Mean platelet serotonin (ng/10(9) platelets) was 310 for the CTH group, 384 during migraine headache, 474 for normal control subjects and 514 in headache-free migrainous patients. There was significant statistical difference of values between CTH patients and those of normal control subjects as well as headache-free migrainous patients, but not of those of migrainous patients during headache. It is suggested that CTH is a low serotonin syndrome, representing one end of the spectrum of idiopathic headache, the other end being represented by migraine.

Adult↗
PubMed1989

Headache: classification, mechanism and principles of therapy, with particular reference to migraine.

The sensation of pain derived from intracranial and extracranial blood vessels is conveyed to the central nervous system chiefly by the trigeminal nerve, with first order neurones terminating in the nucleus caudalis of the spinal trigeminal tract and an area lateral to the dorsal horn of the spinal cord at the second cervical segment. The evoked discharge of second order neurons can be suppressed by activation of the endogenous pain control system or, in about one third of cases, by the local application of ergot derivatives or the serotonin (5HT1) agonist sumatriptan (GR43175). Stimulation of brainstem structures such as locus ceruleus, raphe nuclei and the trigeminal system induce changes in the cerebral and extracranial circulations of the experimental animal that mimic those of migraine with aura (classical migraine). Clinical and laboratory observations have led to a neural hypothesis for migraine in which changes in hypothalamic function (an 'internal clock') and reactions to stress or excessive afferent stimuli are thought to initiate brainstem activity, causing secondary vascular changes and release of inhibition of the trigeminal pain pathways to cause headache. Painful distension of cranial blood vessels may contribute the throbbing component to migraine headache. Migraine is associated with a lowered level of platelet serotonin that is thought to reflect monoamine depletion in brainstem nuclei. Migraine headache can be precipitated by reserpine, which releases serotonin from body stores, and relieved by the intravenous infusion of serotonin. The new 5HT1 agonist sumatriptan promises to have the beneficial effects of serotonin without the side-effects that limited its clinical use.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1989

Neurological disorders in AIDS: a study of 18 cases.

Neurological disorders were studied in 18 patients diagnosed to have AIDS and their findings are analysed. Amongst the problems seen were toxoplasmosis (9), cryptococcal meningitis (5), tuberculous meningitis (1), AIDS dementia complex (3), peripheral neuropathy (2), vertebrobasilar stroke, and a possible AIDS myelopathy in one case each. Their findings are discussed, and literature on the neurological disorders in AIDS reviewed.

Acquired Immunodeficiency Syndrome↗