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Biomedical subjects

D L Jackson

Publications and source records attributed to D L Jackson.

At least 55 records · Page 3Linked to original sources
PubMed1984

Effect of thiopental therapy on cerebral blood flow after total cerebral ischemia.

The effect of barbiturate coma upon regional cerebral blood flow (RCBF) and ultimate neurologic outcome was examined after total cerebral ischemia (TCI). TCI was induced in dogs using a relatively noninvasive double-occlusion balloon technique; cardiopulmonary protection was provided during the period of ischemia. RCBF was measured using 15-mu radioactively labeled microspheres. A reproducible pattern of impaired reperfusion of the central nervous system (CNS) was observed in control animals after the restoration of cerebral perfusion pressure after TCI. This pattern was accentuated by the administration of pentothal to induce barbiturate coma. The additional depression in RCBF in those animals receiving pentothal was most prominent in cortical gray matter and brainstem structures at 3 and 6 h after TCI. It was also observed in cortical white matter. No untreated animal surviving TCI achieved a neurologic functional level better than persistent vegetative (decerebrate) survival over 1 wk of observation. Animals receiving 90 mg/kg body weight of pentothal post-TCI demonstrated irreversible cardiogenic shock related to the myocardial depressant effect of the drug. Animals receiving 40 to 60 mg/kg of pentothal post-TCI demonstrated a survival rate similar to that of untreated animals. Although this study did not establish the possible effectiveness of barbiturate coma in improving residual neurologic damage after TCI, the data do demonstrate that any possible effectiveness in this model is not associated with any improvement in the markedly decreased cerebral perfusion after TCI.

Animals↗
PubMed1984

ICU visiting policies.

Head nurses from 78 ICUs in 37 northeast Ohio hospitals were interviewed about visiting policies. There was tremendous variation with regard to frequency and length of visits; 25% of these ICUs allowed only 2 visits/day, and 42% restricted visits to under 20 min. Most units rarely or never allowed children under 12 yr old to visit. Traditional rationales for restricted visiting are not supported by studies in the literature, nor are they consistent with current concepts of patients' rights. In an era where high technology and medicine by-the-numbers threaten to dehumanize patients, open visiting is an important part of the humanization process.

Adult↗
PubMed1984

A computer-assisted monitoring system for arrhythmia detection in a medical intensive care unit.

The arrhythmia detection capability of a computer-assisted monitoring system (CAMS) was studied in a large multidisciplinary ICU during an 18-month period. Four patient categories were evaluated: critically ill patients on mechanical volume respirators (group 1), patients with uncomplicated acute myocardial infarction (group 2), pacemaker-dependent patients (group 3), and patients on telemetry monitoring (group 4). ECG abnormalities were interpreted by the computer algorithm and recorded on paper. The same ECG abnormalities were analyzed independently by at least two critical care physicians unaware of the computer interpretations. The incidence of false-positive diagnoses (computer system errors) ranged from 10 in 1000 beats in groups 1, 2, and 4, to 20 in 1000 beats in group 3. Movement artifact accounted for 55.3% of all false-positive diagnoses. Of the total number of beats interpreted by the computer, 0.8% were false negatives and 3.8% were true positives. The most frequent true positive was pacemaker malfunction, which was diagnosed with 94% accuracy by the arrhythmia detection system. Significantly, rhythm abnormalities occurred as frequently in patients ventilated with mechanical respirators as in patients with acute myocardial infarction.

Arrhythmias, Cardiac↗
PubMed1983

Acute fulminant toxoplasma meningoencephalitis in a homosexual man.

A homosexual man with a history of sexually transmitted infections including recent giardiasis and high cytomegalovirus (CMV) titer was admitted with generalized weakness, headache, and depression. He rapidly became comatose and developed signs of increased intracranial pressure. CT scan revealed a right cerebral lesion. Pathologic examination disclosed an acute necrotizing granulomatous toxoplasmosis involving the cerebrum. This case represents an example of an opportunistic infection in a male homosexual associated with fulminant clinical course, probably on the basis of immune deficiency.

Acute Disease↗
PubMed1983

A national survey of hospital ethics committees.

A telephone survey of 602 randomly selected hospitals was conducted to identify existing ethics committees, i.e., those with the potential to become involved in the decision-making process in specific cases. Using the number of acute care beds as the criterion, hospitals were divided into 2 groups: (1) over 200 beds; n = 400; (2) 200 or fewer beds; n = 202. Chairpersons of identified committees completed detailed questionnaires. Seventeen committees were found--approximately 1% of all U.S. hospitals. A typical committee included physicians, clergymen, and other professionals. Almost all committees were advisory, not decision-making bodies, and considered very effective by their chairpersons. Ethics committees have not, however, solved current medical ethical problems; nor have they allayed the concerns of patients' rights advocates about patient representation and control. Further study is warranted.

Ethical Review↗
PubMed1983

Translocation and Metabolism of Endosperm-Applied [2-C] Indoleacetic Acid in Etiolated Avena sativa L. Seedlings.

The role of free indole-3-acetic acid (IAA) in the endosperm of Avena sativa L. seedlings was investigated to determine its contribution to free IAA in the shoot. [2-(14)C]IAA was injected into the endosperm of darkgrown seedlings and the transport and metabolism of the [(14)C]-labeled compounds determined. It was concluded that translocation of free IAA directly from the endosperm is probably not a significant source of free IAA in the shoot, mainly because even small amounts of [(14)C]IAA introduced into the endosperm were rapidly metabolized. This suggested that, in Avena, free IAA does not normally exist in the liquid endosperm.

Journal Article↗
PubMed1982

Relative error and variability in blood flow measurements with radiolabeled microspheres.

The validity of blood flow measurements made using radiolabeled microspheres (reference sample technique) has been well established in a variety of experimental models. Previous studies of the variability of the method emphasize tissue sphere number as the principle source of random variation. However, blood flow measurements depend on sphere distribution to both tissue and reference samples as well as on quantitation of different isotopes in a single tissue sample. In this study we examined the major determinants of relative error and variability in flow rate measurements inherent in the reference sample technique. Error magnitude was predicted from a statistical model, simulated with numerical analogs, and measured in anesthetized dogs with 15-micrometers microspheres. Theoretically, with 2,000 spheres in the reference sample and greater than or equal to 475 spheres in a tissue sample, blood flow can be measured with 10% accuracy at the 95% confidence level and with duplicate variability of 14%. Random errors in isotope quantitation were influenced by the specific activity of the isotope and the fractional distribution of a given isotope over the various energy windows. Suspension of tissue and reference sample spheres at different heights (0.2 cm) resulted in systematic flow errors of up to 13%. When errors due to separation of isotopes and differences in sample height were minimized, the major determinant of variability in flow measurements during simultaneous injection of differently labeled microspheres was the number of spheres in both tissue and reference samples.

Animals↗
PubMed1979

Staff attitudes towards the care of the critically ill in the medical intensive care unit.

In an attempt to study the basis for conflict and tension surrounding decision making in ICU settings, a questionnaire was used to examine staff attitudes in a newly opened medical ICU in four major areas: (1) ethical issues; (2) decision-making process; (3) communications; and (4) emotional reactions of staff. All of the 36 house officers and 32 of 34 nurses (all RNs) completed the questionnaire. Results showed there was no monolithic nursing as opposed to physician position on any issue. Futhermore, professional role exerted a more profound influence on attitudes than gender or religious background. There was remarkable agreement between physician and nurse groups on ethical issues. However, nurses were less satisfied with the decision-making process and communication in the medical ICU and were more aware than physicians of their own and other's emotional reactions. The results suggested four ways to reduce tension in the medical ICU: (1) frankly recognize the inevitability of conflict and tension in a system where physicians have ultimate authority; (2) avoid perpetuating stereotypes; (3) maximize the continuity of physician care; and (4) maximize communication between and within professional groups.

Attitude of Health Personnel↗
PubMed1979

Isaacs syndrome with laryngeal involvement: an unusual presentation of myokymia.

A woman with widespread myokymia presented initially at age 19 with hoarseness and mild dyspnea on exertion. The diagnosis of Isaacs syndrome was suggested by the clinical findings of widespread continuous muscle activity and depressed tendon reflexes, although she lacked the usually prominent increased muscle tone. The diagnosis was confirmed by the electromyographic demonstration of continuous spontaneous muscle action potentials that were abolished by neuromuscular blockade but not by local nerve blockade. Pulmonary function tests were consistent with fixed extrathoracic obstruction. The vocal cords were closely approximated. Electromyographic studies of the laryngeal muscles under general anesthesia revealed continuous muscle activity, which accounted for the hoarseness and much of the exertional dyspnea. The patient responded well to treatment with phenytoin and carbamazepine. This unusual syndrome should be considered in the differential diagnosis of patients with respiratory complaints and muscle fasciculations, even though they have normal muscle tone.

Action Potentials↗
PubMed1978

Decreased pulmonary vascular responses in dogs with increased pulmonary blood flow.

We wished to determine whether high pulmonary blood flow alters the pulmonary vascular responses to the vasoconstrictors, hypoxia and prostaglandin F2alpha (PGF2alpha). Acute or chronic left pulmonary artery (PA) occlusion was performed in dogs in order to create high pulmonary blood flow conditions. Right lung pulmonary vascular resistance (PVR) during normoxia was reduced by both acute and chronic left PA occlusion, suggesting passive vasodilatation. Increases in right lung PVR induced by hypoxia (10--15% O2) and PGF2alpha (0.8-4 microgram kg-1 min-1) were attenuated both in acute and chronic left PA occluded dogs. Since the reductions in responsiveness were similar with acute and chronic increases in blood flow, the attenuating effect of high blood flow was not dependent upon morphologic changes in the vasculature. Pulmonary vascular responsiveness was probably reduced in these animals due to their dilated pulmonary vascular beds, consequent to the increased blood flow, thereby decreasing the effectiveness of smooth muscle contraction.

Animals↗
PubMed1977

Pellagra: an analysis of 18 patients and a review of the literature.

The clinical and laboratory features of 18 adult pellagrins are reviewed. Only four patients (22%) had the full trial of dermatitis, diarrhea and dementia. Dermatitis alone occurred in six(33%), dementia in five(28%) and dermatitis and diarrhea in three(17%). In one patient, dermentia was the initial sign of a relapse. Steatorrhea was found in six patients and was usually associated with marked alopecia. Edema without evidence of cardiac failure was present in seven patients. A diffuse increase in slow wave activity on the electroencephalogram was characteristic in patients with dementia. Fever occurred in 14 patients, and an infection was documented in 10 of these. Common laboratory abnormalities included a normochromic, normocytic anemia, lymphopenia, eosinopenia hyperuricemia, and low serum levels of albumin, urea, cholesterol, carotene, potassium, calcium, and magnesium. Adrenal and thyroid function were normal, but a low serum T4, high serum free T4, and an elevated T3 resin uptake were frequently observed. These abnormalities were corrected with treatment of the underlying nutritional disorder. In two patients initially treated with thiamine alone, and in one who received inadequate amounts of niacin and protein, there was marked deterioration of mental function, which responded to administration of niacin and proper diet.

Adult↗
PubMedDate not supplied

Total cerebral ischemia: a new model system for the study of post-cardiac arrest brain damage.

The pathophysiology of post-cardiac arrest brain damage is not well understood. Many of the model systems presently used to study global ischemia have serious limitations. A new model system for total cerebral ischemia (TCI), using aortic and inferior vena caval occlusion balloons, is described. This model system produces verifiable TCI and avoids surgical invasion of the thorax or the use of vasoactive drugs. It does not impede cerebral venous return and protects the cardiopulmonary system from damage. This model system can be used to study the efficacy of various therapeutic interventions following a standardized CNS global ischemic insult.

Animals↗