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Biomedical subjects

J H Wood

Publications and source records attributed to J H Wood.

At least 19 recordsLinked to original sources
PubMed1991

Experimental isovolemic haemodilution-induced augmentation of carotid blood flow and oxygen transport through graded carotid stenoses.

The effect of haemodilution without volume expansion (isovolemic haemodilution) was assessed with respect to blood flow and oxygen transport across stenotic lesions of progressive severity in the dog carotid artery. As the mean haematocrit (Hct) was reduced from 40 +/- 1% (+/- SEM) to 32 +/- 0% (p less than 0.001), reductions in vascular resistance were significant across the 90% (p less than 0.001) and 95% (p less than 0.0003) relative carotid stenoses. Isovolemic haemodilution reduced fresh blood viscosity significantly by 27 +/- 3% (p less than 0.001) and 42 +/- 4% (p less than 0.001) at the low shear rates of 10 sec-1 and 1 sec-1 which are typical of low-flow states. Following a 20% reduction in Hct 30 to 35% increase (p less 0.001) in carotid blood flow occurred at non-critical degrees of stenosis while a mean 83% increase (p less than 0.001) occurred at the highly critical 95% relative stenosis. Oxygen transport after a 22% decrease in blood haemoglobin was significantly increased by 28% (p less than 0.01) at the 95% relative stenosis level. These data provide a physiologic rationale for the beneficial effects of haemodilution in acute cerebral ischaemia, cerebral vasospasm and cerebral revascularization or carotid endarterectomy.

Animals↗
PubMed1990

LC determination of the diastereomers of 1-(beta-D-glucopyranosyl)phenobarbital in human urine.

The "product enantioselectivity" associated with the urinary excretion of the phenobarbital N-glucoside conjugates has not been determined previously. A liquid chromatography method using gradient elution was developed for quantifying both phenobarbital N-glucoside conjugates, phenobarbital, and p-hydroxyphenobarbital. Following a single oral dose of phenobarbital to male Caucasian and Oriental subjects, both phenobarbital N-glucoside conjugates were observed in the urine. In seven subjects, 3.3-10.6% of the phenobarbital dose was detected as a single phenobarbital N-glucoside (S configuration at the C-5 position of the barbiturate ring). The other phenobarbital N-glucoside diastereomer accounted for less than 1.5% of the phenobarbital dose. The urinary excretion of the major phenobarbital N-glucoside diastereomer paralleled the urinary excretion of phenobarbital and was comparable in both Caucasian and Oriental subjects. These results indicate a pronounced selectivity for the formation and/or urinary excretion of the phenobarbital N-glucosides.

Asian People↗
PubMed1979

Cerebral abscesses produced by bacterial implantation and septic embolisation in primates.

The degree of brain abscess encapsulation is positively related to surgical mortality and methods to enhance capsule wall formation, therefore, have therapeutic relevance. Two primate models are described which may be useful in the investigation of encapsulation of traumatic and metastatic brain abscesses. Direct intracerebral inoculation induces abscesses displaying more prominent inflammatory responses and encapsulation than does septic embolisation, despite similar abscess age and size. Cerebral ischaemia surrounding metastatic suppurative foci may retard capsule wall formation.

Animals↗
PubMed1979

CSF HVA and 5-HIAA.

Explore the source record for details and available documents.

Homovanillic Acid↗
PubMed1979

Low cerebrospinal fluid gamma-aminobutyric acid content in seizure patients.

Gamma-Aminobutyric acid (GABA) has been implicated in the neurochemistry of epilepsy. Lumbar cerebrospinal fluid (CSF) GABA concentrations determined using an ion-exchange fluorometric assay reflect brain GABA content. The mean lumbar CSF GABA concentration among 21 medicated patients with intractable seizures was significantly lower (p less than 0.001) than that of 20 unmedicated normal volunteers. Patients with generalized tonic-clonic (grand mal) and complex partial (psychomotor) seizures had significantly lower (p less than 0.05) CSF GABA concentrations than those with simple partial (focal sensory/motor) seizures. Although lumbar CSF GABA levels in our seizure patients did not significantly correlate with serum concentrations of phenytoin, phenobarbital, or primidone, additional study of medication-free epileptic patients may be required to evaluate the possibility of anticonvulsant-drug-induced CSF GABA alterations.

Adult↗
PubMed1979

CSF calcium: clinical correlates in affective illness and schizophrenia.

In a study of electrolytes in lumbar cerebrospinal fluid (csf) from psychiatric patients, the authors found a positive correlation between calcium concentration and symptom severity in hospitalized depressed patients. CSF calcium levels tended to decrease as patients improved. In four rapidly cycling patients, CSF calcium was higher during depression than during mania. Mean CSF calcium for the depressed patients as a group was not significantly different from neurological controls or other psychiatric patients. Symptom remission from acute psychosis in schizophrenic patients was accompanied by a significant increase in CSF calcium concentration. These findings are discussed in relationship to calcium-induced alterations in neuronal and physiological excitability.

Bipolar Disorder↗
PubMed1978

Tetracycline. Another example of generic bioinequivalence.

Because of the Food and Drug Administration batch certification assurances, state government systems generally purchase antibiotics from the lowest bidder. A tetracycline hydrochloride tablet purchased in this manner is shown to be inferior to the innovator capsule product.

Biological Availability↗
PubMed1978

Probenecid-induced norepinephrine elevations in plasma and CSF.

Probenecid administered in divided oral doses totaling 100 mg/kg increased levels of norepinephrine (NE) in plasma and cerebrospinal fluid (CSF). This technique is commonly used to measure the rate of accumulation of acidic metabolites of certain brain neurotransmitter biogenic amines in CSF after blockade of their transport into blood. Since levels of 3-methoxy-4-hydroxy-phenylethyleneglycol, a neutral metabolite of NE, are also elevated after high oral doses of probenecid, the increases of CSF and plasma NE levels may be directly related to probenecid-induced release of this amine from noradrenergic neurons. In patients who experienced nausea or vomiting there were lower levels of probenecid in CSF, probably secondary to diminished absorption of the medication. These patients also had lower levels of NE in plasma than did patients who remained asymptomatic.

Adolescent↗
PubMed1978

Cerebrospinal fluid norepinephrine in affective illness.

The authors measured cerebrospinal fluid norepinephrine concentrations in manic, depressive, and neurological control patients with and without probenecid administration. Baseline and probenecid norepinephrine values were significantly higher in manic than in depressed patients, who did not differ significantly from the neurological patients. Depressed patients with high levels of anxiety had higher levels of norepinephrine than those with low anxiety. These data suggest that alterations in mood or motor activity may be associated with changes in central norepinephrine metabolism in man.

Anxiety↗
PubMed1978

Role of vascular proliferation on angiographic appearance and encapsulation of experimental traumatic and metastatic brain abscesses.

Experimental traumatic abscesses were produced in rhesus monkeys by intracerebral injection of nutrient agar contaminated with Staphylococcus epidermidis, and metastatic abscesses were induced by intracarotid embolization of silicone cylinders contaminated with Staphylococcus epidermidis. All monkeys underwent preoperative and serial postoperative carotid angiography. Traumatic abscesses produced early capsular blushes and progressive anterior cerebral artery displacements. Metastatic abscesses induced transient midline shifts but no capsular stains. Postmortem studies on the monkeys showed that mean capsular thickness and segmental wall vascularity of the traumatic and metastatic abscesses were significantly different (p less than 0.001), despite equal abscess ages and similar abscess volumes. In comparison to traumatic abscesses, metastatic abscesses demonstrated reduced inflammatory cell infiltration and retarded collagen formation around proliferating capsular vessels. Brain surrounding the metastatic abscesses demonstrated ischemic changes. The results suggest that 1) capsular blushes during cerebral angiography are secondary to vascular proliferation within the capsule and not to compression of surrounding brain, 2) vascular staining reflects capsular thickness, 3) capsular vascularity contributes to collagen formation, 4) encapsulation is dependent upon the integrity of surrounding brain, and 5) adjacent cerebral ischemia may impede inflammatory responses involved in capsule formation.

Animals↗
PubMed1978

Outcome following severe head injuries in children.

The outcome in 53 children following severe head injury is presented. All children were graded using the Glasgow Coma Scale; 90% made a good recovery or were moderately disabled, and 8% died or were left vegetative. All patients were treated with controlled ventilation and steroids; mannitol, and, if necessary, Nembutal (pentobarbital) were used to maintain the intracranial pressure below 20 torr. With this regimen, only one death occurred due to uncontrollable intracranial hypertension. All patients with a coma scale of 5 or greater recovered well. The worst prognostic sign was the presence of flaccidity: 33% of these patients died or were vegetative. Five of seven patients who were decerebrate or flaccid with bilateral fixed pupils and absent caloric responses made a good recovery or were moderately disabled. The relatively low incidence of mass lesions (23%) and high incidence of diffuse cerebral swelling (34%) suggest a different pathophysiological response of the child's brain to injury, which may play a role in the improved survival of children following severe head injury when compared to adults.

Adolescent↗
PubMed1977

Primate model for long-term study of intraventricularly or intrathecally administered drugs and intracranial pressure.

Meaningful pharmacokinetic investigations require animal systems which approximate the human situation. This report describes a primate model in which silicone catheters are placed into the fourth ventricle and the spinal subarachnoid space and connected to subcutaneous cerebrospinal fluid without tissue damage, prod, enables spinoventricular perfusion, and permits ventricular cerebrospinal fluid sampling over extended periods in unanethetized rhesus monkeys. This animal system may provide intraventricular pressure recordings and pharmacokinetic data similar to that obtained in man.

Animals↗