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Biomedical subjects

K M Welch

Publications and source records attributed to K M Welch.

At least 163 records · Page 9Linked to original sources
PubMed1989

Preliminary observations on brain energy metabolism in migraine studied by in vivo phosphorus 31 NMR spectroscopy.

We measured brain energy phosphate metabolism and intracellular pH (pHi) in a cross-sectional study of migraine patients by in vivo phosphorus 31 NMR spectroscopy. During a migraine attack the ratio ATP/total phosphate signal (mole % ATP) was preserved, but there was a decrease in mole % phosphocreatine (PCr) and an increase in mole % inorganic phosphate (Pi) resulting in a decrease of the PCr/Pi ratio, an index of brain phosphorylation potential. This was found in classic but not common migraine. Mole % Pi was also increased in combined brain regions between attacks. There was no alteration in brain pHi during or between attacks. Energy phosphate metabolism but not pHi appears disordered during a migraine attack.

Adenosine Triphosphate↗
PubMed1989

The effects of aging on cerebral blood flow in migraine.

We studied cerebral blood flow (CBF) with the 133xenon inhalation technique in 92 migraine patients (49 classic/complicated, 43 common), aged 19 to 85 years, in the headache-free period. We compared results to 49 control subjects, aged 22 to 80 years. CBF declined with age in both groups, but at a slower rate in migraine patients, a difference most pronounced in classic migraine. CBF was lower in migraine patients than in controls under 48 years of age. In addition, regional asymmetry of blood flow was found more frequently in young migraine patients than in controls. These results suggest that differences exist in cerebrovascular resistance tone in migraine patients, which may contribute to the threshold for a migraine attack and result in differing age-related changes in blood flow.

Adult↗
PubMed1988

Prolonged deterioration of ischemic brain energy metabolism and acidosis associated with hyperglycemia: human cerebral infarction studied by serial 31P NMR spectroscopy.

We report on a patient with a large ischemic hemispherical stroke studied serially by 31P nuclear magnetic resonance spectroscopy. Persistent hyperglycemia was associated with prolonged acidosis in ischemic brain and failure of high-energy phosphate metabolism to recover. These in vivo human data support the concept that hyperglycemia adversely affects ischemic brain metabolism, pH, and clinical outcome.

Acidosis↗
PubMed1988

Visual symptoms associated with the presence of a lupus anticoagulant.

The lupus anticoagulant is an acquired serum immunoglobulin that prolongs several coagulation parameters, most notably the partial thromboplastin time (PTT). Most commonly, this condition is found in association with systemic lupus erythematosus (SLE) but may be seen with other collagen-vascular diseases and in otherwise healthy individuals. Despite the laboratory tests suggesting impaired coagulation, clinically the lupus anticoagulant has been associated with thrombosis. The authors present five patients with the lupus anticoagulant who came to medical attention because of branch retinal artery occlusion, ischemic optic neuropathy, transient visual loss, transient diplopia, or vertebrobasilar insufficiency. Eleven previously reported patients with the lupus anticoagulant and disturbed vision are also reviewed with additional findings of retinal venous occlusive disease and homonymous visual field loss. The relationship of these findings to retinopathy in SLE is discussed. Patients with the lupus anticoagulant (with or without SLE) may develop disturbances in vision due to thrombosis from a hypercoagulable state. We recommended obtaining a PTT, VDRL, and the more sensitive anticardiolipin antibody in patients with unexplained visual symptoms.

Adult↗
PubMed1988

Brain pH in migraine: an in vivo phosphorus-31 magnetic resonance spectroscopy study.

The intracellular pH (pHi) of cerebral cortex was measured in migraine patients by use of in vivo phosphorus-31 NMR spectroscopy. No changes in pHi were measured during a migraine attack. The long-standing concept that the headache of migraine is due to cerebral vasodilation induced by prodromal vasospasm-induced ischemic acidosis is not substantiated.

Adult↗
PubMed1988

Baseline and activated platelet cytoplasmic ionized calcium in acute ischemic stroke. Effect of aspirin.

We measured cytoplasmic ionized calcium concentrations [( Cai2+]) in aequorin-loaded gel-filtered platelets from 38 patients with acute occlusive stroke (12 treated with aspirin, 26 untreated) and 25 healthy controls. Compared with controls, baseline [Cai2+] was higher in untreated patients (p less than 0.002), maximal 36-72 hours after the onset of neurologic dysfunction (p less than 0.0001), in those patients with as well as those without major stroke risk factors. The increase in [Cai2+] after stimulation with 0.5 and 1.0 unit/ml thrombin (p less than 0.05), 2 and 4 micrograms/ml collagen (p less than 0.02), and 0.5 and 1.0 mM platelet activating factor (p less than 0.05) were also greater in untreated patients, but the profiles of these changes were parallel to those in controls. Even though the platelets of stroke patients are more sensitive to activation, they are functionally similar to those of controls. Aspirin treatment reduced baseline [Cai2+] as well as thrombin- and collagen-induced [Cai2+] changes. Platelet activating factor-induced increase in [Cai2+] was not altered by aspirin treatment. Our results suggest that the usefulness of aspirin in stroke is limited because aspirin does not suppress platelet responsiveness to all in vivo thrombogenic stimuli. Specific platelet activating factor antagonists may prove to be useful therapeutic agents in stroke.

Acute Disease↗
PubMed1988

Global cerebral ischemia and intracellular pH during hyperglycemia and hypoglycemia in cats.

In 27 cats treated to vary arterial serum glucose concentrations, we measured cerebral high-energy phosphate metabolite concentration and intracellular pH using in vivo phosphorus-31 nuclear magnetic resonance spectroscopy during transient global cerebral ischemia and reperfusion. Hypoglycemia was induced with 4 units/kg i.v. insulin in six cats before ischemia; hyperglycemia was induced with 1.5 g/kg i.v. glucose in six cats before and in six cats during ischemia. Nine untreated cats subjected to ischemia without manipulation of blood glucose concentration served as controls. During ischemia, intracellular pH fell to similar levels in the control and both hyperglycemic groups. During reperfusion, the hyperglycemic before ischemia group initially exhibited a severe further decline in intracellular pH (p less than 0.003); this further decline was not observed in the control or the hyperglycemic during ischemia groups. Intracellular acidosis was attenuated both during ischemia and early after reperfusion in the hypoglycemic before ischemia group. In all groups, cerebral high-energy phosphate metabolite concentrations were depleted during ischemia and then recovered to the same degree during reperfusion. Our data suggest that brain glucose stores before ischemia determine the severity and time course of intracellular acidosis during ischemia and reperfusion.

Animals↗
PubMed1988

Superior cerebellar artery infarction and vertebral artery dissection.

Isolated superior cerebellar artery infarction is rare, and the mechanism is often not readily apparent. We describe a patient with an isolated superior cerebellar artery infarction resulting from an ipsilateral vertebral artery dissection. Angiography demonstrated intraluminal clot in the superior cerebellar artery, suggesting artery-to-artery embolus as a mechanism of this uncommon stroke syndrome.

Adult↗
PubMed1988

Effect of mild hyperthermia on recovery of metabolic function after global cerebral ischemia in cats.

We investigated the effect of mild whole-body hyperthermia before and after 16 minutes of global cerebral ischemia on metabolic recovery during recirculation in cats using in vivo phosphorus-31 nuclear magnetic resonance spectroscopy. Hyperthermia (temperature 40.6 +/- 0.2 degrees C) was induced greater than or equal to 1 hour before ischemia and was maintained during 1.5-2 hours of recirculation in nine cats; four cats were subjected to hyperthermia without cerebral ischemia, six to hyperthermia during recirculation (after return of intracellular pH to preischemic values), and 14 to normothermic ischemia and recirculation. Our data indicate that preischemic hyperthermia results in an intracellular cerebral pH during recirculation significantly lower than that in normothermic cats. In hyperthermic cats beta-ATP and phosphocreatine (PCr) concentrations and the ratio of PCr to inorganic phosphate failed to return to preischemic levels during recirculation in contrast to normothermic cats. Hyperthermia without ischemia and hyperthermia during recirculation had no significant effect on intracellular pH. Thus, preischemic hyperthermia has a detrimental effect on metabolic recovery after transient global cerebral ischemia.

Acidosis↗
PubMed1988

Bilateral posterior cerebral artery strokes in a young migraine sufferer.

We report a young migraine sufferer who developed bilateral posterior cerebral artery territory infarcts during the course of his classic migraines, the second of which was associated with intraluminal clot in the posterior cerebral artery. To our knowledge, bilateral posterior cerebral artery stroke from spontaneous migraine has not been reported. Head computed tomographic, magnetic resonance imaging, and angiographic correlation is presented. The mechanism of migrainous infarction may be in part explained by caliber changes in arterioles and capillaries leading to flow reduction in the more proximal conduit arteries combined with the associated coagulopathy that has been previously documented during migraine attacks.

Adult↗
PubMed1988

Cerebral blood flow asymmetry in the detection of extracranial cerebrovascular disease.

Regional cerebral blood flow was measured by the 133Xe inhalation technique in patients with unilateral carotid occlusion, unilateral carotid occlusion and contralateral carotid stenosis, bilateral carotid occlusion, or normal arteriograms. After adjusting for age, sex, and history of stroke, hemispheric blood flow asymmetry was shown to be a predictor of unilateral carotid occlusion with a sensitivity of 80.6% and a specificity of 80.5%. Asymmetry of regional cerebral blood flow is useful in the assessment of patients with extracranial cerebrovascular disease.

Adult↗
PubMed1988

Sneddon's syndrome: an antiphospholipid antibody syndrome?

A 44-year-old woman with livedo reticularis, multiple ischemic strokes, and transient ischemic attacks (Sneddon's syndrome) had antiphospholipid antibodies--the lupus anticoagulant and anticardiolipin antibodies. This patient provides support for the hypothesis that these antibodies are involved in the pathogenesis of this rare but now potentially treatable disorder.

Antibodies↗