Biomedical subjects
Publications and source records attributed to S R Donaldson.
Three patients with major depression superimposed on chronic dysthymia were treated with phenelzine. After an initial excellent response, each patient relapsed and developed a severe chronic depression that was refractory to other treatments. The implications for the long-term effects of phenelzine treatment are considered.
Vagal baroreflexes were studied by measuring the atropine-sensitive cardioinhibition produced by raising arterial pressure with phenylephrine in anesthetized rats pretreated with the beta-adrenergic receptor antagonist nadolol. Sympathetic baroreflexes were determined in halothane-anesthetized rats by measuring the inhibition of lumbar sympathetic discharge produced by elevating arterial pressure with gradual aortic constriction. Both reflexes were drastically reduced by bilateral injections of 2.2 nmol of the glutamate receptor antagonist kynurenic acid (KYN) into either the nucleus of the solitary tract (NTS) or the ventrolateral medulla between 0 and 1 mm posterior to the level of the obex. Injections of KYN elsewhere in the medulla were generally ineffective and injections of 8-OH kynurenate (an inactive analog) into the ventrolateral medulla or NTS were also without effect. KYN injections (2.2 nmol) into the intermediate portion of the NTS produced small increases in mean arterial pressure (0-15 mm Hg) and no change in heart rate while injections of similar amounts into the ventrolateral medulla at obex level were followed by large (35-116 mm Hg) increases in pressure and bradycardia. Both types of injections produced a similar degree of blockade of vagal and sympathetic baroreflexes. These results support previous evidence that baroreceptor primary afferents may release a glutamate-like transmitter in the NTS and indicate that a similar type of excitatory transmitter is involved at the level of the ventrolateral medulla in mediating or modulating both vagal and sympathetic baroreflexes. Finally the bradycardia and hypertension produced by blocking amino acid receptors in the ventrolateral medulla appear largely unrelated to the disruption of peripheral baroreceptor inputs.
Pharmacologic agents currently used or being studied for the treatment of schizophrenia are reviewed. Neuroleptic medications are still the mainstay of treatment, but recent studies suggest new approaches to dosage and to the treatment of acute psychosis. Lithium is beneficial in psychotic illnesses with acute onset and a remitting course, regardless of the acute psychotic symptoms. Antidepressant agents may ameliorate depression in psychotic patients, but do not improve psychotic symptoms or social withdrawal. Propranolol's reported antipsychotic action has not been confirmed by controlled studies, but the drug may have a role in treating organic psychoses. The benzodiazepines, clonidine, and carbamazepine all merit more investigation as possible treatments for psychosis. The implications of differential treatment response among schizophrenic patients are discussed.
An analytical system for measuring size, motion, and light absorption of objects in the field of a microscope is described. The design criteria have been chosen to produce a system that permits acquisition of densitometric information at a number of points within the field and permits computation of important variables from the densitometric data. Relatively simple fiber-optics systems for sampling light intensity at selected locations in the microscope field are described. Computer programs are outlined that permit computation of microvessel diameter, red cell velocity, and hemoglobin oxygen saturation. The sampling systems and programs are quite general in nature and should be applicable to other types of related measurements and computing devices.
A 37-year-old male patient developed sialorrhea while being treated with lithium carbonate. The sialorrhea was associated with salivary gland enlargement and was reversed by discontinuation of lithium. Concomitant treatment with propantheline bromide provided symptomatic relief.