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Biomedical subjects

F D Brown

Publications and source records attributed to F D Brown.

At least 19 recordsLinked to original sources

Epidural lipomatosis in steroid-treated patients.

Epidural lipomatosis is a condition in which excess adipose tissue is deposited circumferentially about the spinal cord in the epidural space. It is most frequently seen in patients on chronic steroid treatment for a variety of medical problems and can present as nonspecific back pain, radiculopathy, or frank spinal cord compression. Diagnosis and treatment have generally relied on multi-level decompressive laminectomy after myelography and computed tomography. The immunocompromised state and the reported postoperative mortality (22%) of these patients, however, suggests that nonoperative therapy may be preferable whenever possible. Five cases of epidural lipomatosis are reported, and previous literature is reviewed for presentation, evaluation, and treatment of this condition.

Adult

Cerebral blood flow during the acute therapy of severe hypertension with oral clonidine.

A major risk associated with the acute treatment of severe hypertension is a reduction in cerebral blood flow (CBF) with ischemic injury to the central nervous system. The authors studied CBF before and after the acute treatment of severe hypertension (diastolic blood pressure greater than 115 mm Hg) with clonidine in 13 patients. One patient did not reach goal blood pressure (diastolic blood pressure 105 mm Hg or a decrease by 30 mm Hg) after clonidine alone. In the remaining 12 patients, oral clonidine reduced supine blood pressure from 201.7 +/- 5.0/126.3 +/- 2.1 mm Hg to 149.4 +/- 5.3/96.8 +/- 1.7 mm Hg over an average time period of 85 +/- 7 minutes. Although mean CBF for the group did not change (72.6 +/- 4.2 v 73.7 +/- 3.5 mL/100 mg/min), a significant (greater than 10%) change occurred in 9 of the 12 patients (5 increases and 4 reductions). The magnitude and direction of the change were dependent upon initial CBF (r = -0.65, P less than .05); patients with low pretreatment CBF experienced an increase, whereas those with high initial flow exhibited a decrease. No significant adverse effects were observed. These data confirm previous reports that clonidine is effective in the acute treatment of severe hypertension and demonstrate that its effects on CBF are determined by the pretreatment levels of flow.

Administration, Oral

Superior sagittal sinus infection with Petriellidium boydii: case report.

A case of infection of the superior sagittal sinus with Petriellidium boydii is reported. This relatively common fungal pathogen rarely invades the central nervous system. Immunological compromise and poor personal hygiene seem to be common attributes shared by this patient and the 4 previous patients reported to have suffered invasion of the central nervous system by this organism. This report is unique in that it is the first demonstrating apparent hematogenous dissemination of this organism to the central nervous system.

Brain Diseases

The effect of fetal hypothalamus grafts on weight gain resulting from lesions of the ventromedial hypothalamus.

Bilateral ventromedial hypothalamic lesions in female adult rats which resulted in hyperphagia and rapid weight gain were followed by placement of fetal brain tissue in the anterior third ventricle. The treatment group received fetal hypothalamus grafts, and fetal cortical tissue of identical age was grafted into the control group. A significant reduction in average daily weight gain was noted from 4 to 12 weeks following transplantation in the treatment group. At 12 weeks posttransplantation, the animals were sacrificed for histological analysis. Examination of the hypothalamus grafts revealed neurons, ependymal clusters, and axonal processes which appeared to infiltrate the surrounding hypothalamic parenchyma.

Animals

Examination of the utility of the rat as an animal model for human anticoagulation.

The feasibility of employing the rat as an experimental model for investigation of full-dose heparin anticoagulation was assessed. Striking similarities were found to exist between rats and humans regarding baseline-activated partial thromboplastin time (APTT) values, and dosage per kilogram of heparin required to produce an APTT value of 1 1/2-3 times normal, the clinical definition of full-dose heparinization. Based upon these similarities, it appears that the rat can effectively serve as an experimental model for investigating the effects of heparin in humans.

Animals

Treatment of mycotic aneurysms.

Mycotic intracranial aneurysms may be treated by antibiotic therapy alone. Careful evaluation of this mode of treatment has been hampered by inadequate angiographic and microbiological documentation. The present case details the successful conservative management of one of these lesions in a patient who had previously undergone craniotomy for a separate mycotic aneurysm.

Adult

Severe thrombocytopenia associated with phenytoin and cimetidine therapy.

A 67-year-old man developed a sudden onset of severe isolated thrombocytopenia (platelet count, 1000/mm3) after 10 days of phenytoin administration as a prophylactic measure prior to craniotomy. The patient had also been taking cimetidine for 2 months prior to admission. No other hematological complications were noted, and an extensive hematologic investigation was otherwise unremarkable. Rapid resolution of the thrombocytopenia upon discontinuation of phenytoin and cimetidine strongly suggests a drug-induced adverse reaction.

Aged

Evaluation of the risks of anticoagulation therapy following experimental craniotomy in the rat.

The risk of hemorrhagic complications with anticoagulation therapy in patients following intracranial surgery has prevented investigation of the potential use of heparin in the early postoperative period. The authors have evaluated the safety of anticoagulation therapy following experimental craniotomy in male Holtzman rats. The dose and schedule of heparin administration, which elevated and maintained the activated partial thromboplastin time (APTT) within the therapeutic range of 1 1/2 to 3 X control APTT, was alternating doses of 400 and 500 IU/kg injected subcutaneously every 6 hours. This schedule was initiated 2, 4, 7, 10, and 14 days after craniotomy and was continued for 72 hours thereafter. The results demonstrated that the incidence of intracerebral hemorrhage declined as the postoperative interval prior to initiation of anticoagulation increased. If anticoagulation therapy was initiated during the first 7 postoperative days, the risk of intracerebral hemorrhage was high (mean 14.7%): however, if an additional 3 to 7 days elapsed prior to initiation of anticoagulation, the incidence of intracerebral hemorrhage dropped significantly (mean 0%) (p less than 0.05). These results suggest that anticoagulation therapy can be safely initiated 10 to 14 days after craniotomy.

Animals

Detailed monitoring of the effects of mannitol following experimental head injury.

The experimental model of a cerebral missile injury developed by Crockard was used in three groups of Rhesus monkeys treated with mannitol. One group received mannitol 15 minutes after being injured with a BB pellet at 90 m/sec impact. Another group was wounded identically, but mannitol treatment was delayed until 1 hour after injury. The last group was wounded with the missile traveling at 180 m/sec, and mannitol was started 15 minutes after trauma. The data were contrasted with the results from the original model. After receiving mannitol, all groups showed marked improvement in mean blood pressure, cerebral perfusion pressure, cerebral blood flow, and cerebral metabolic rate of oxygen consumption out of proportion to the degree of reduction in intracranial pressure (ICP). The authors conclude that the therapeutic value of mannitol may, in some injuries, be directly related to its effects on blood flow and metabolism, as well as to its better known effects upon ICP.

Animals

Hyperemic and ischemic problems of surgical treatment of arteriovenous malformations.

Three patients with arteriovenous malformations are described who showed signs of massive hyperemia in the vascular territory of the normal brain proximal to arterial ligation. One additional patient had evidence of ischemia of the brain in the territory distal to ligation (steal), and in another both mechanisms were considered as operative hazards.

Adolescent

Treatment of aneurysmal hemiplegia with dopamine and mannitol.

Three patients with severe postoperative hemiplegia and one with hemiplegia following a subarachnoid hemorrhage are presented. None had hematomas. All were treated with dopamine-induced hypertension, mannitol, and large quantities of intravascular fluids. All showed a remarkable degree of clinical improvement, presumably secondary to an increase in cerebral blood flow.

Adult

An experimental cerebral missile injury model in primates.

An experimental model of cerebal missile injury in rhesus monkey is described. The main objective was to create a "clean" wound devoid of bleeding from major vessels and complications due to bone fragments. There was a correlation between the wounding energy and the physiological signs, although we underestimated the actual energy level. After the right parietooccipital to right frontal injury, there was bradycardia, changes in blood pressure, and, in high-energy wounds, a marked alternation in resperation. This suggests that the missile's energy produces direct brain-stem damage, the extent of which can be related to the wounding energy.

Animals