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Biomedical subjects

D A Davis

Publications and source records attributed to D A Davis.

At least 109 records · Page 6Linked to original sources
PubMed1978

The EEMG--a practical index of cortical activity and muscular relaxation.

In a continuing study of the EEG as a monitor of cortical activity during anesthesia using a time-domain wave analyzer, the contamination of the EEG by scalp muscle activity was observed. A measure of this EMG activity was extracted from the combined EEG/EMG wave obtained from two electrodes placed over the left frontalis muscle and right mastoid process. Clinical work with this variable showed that the EMG can serve both as a reliable guide to patient muscular relaxation and an indicator of unacceptable muscle contamination of the EEG. This extracted variable in conjunction with the analyzed EEG has served as a valid indicator in the assessment of the anesthetic state. The system has been successfully employed in the management of nearly 1000 surgical patients.

Anesthesia, General↗
PubMed1977

Prediction of help-seeking with the MMPI: the problem of base rates.

The usefulness of combined elevation of the Depression and Psychasthenia scales of the MMPI as a predictor of psychological help-seeking was investigated for two classes at a small liberal arts college for men. Counseling service use rates during the 4 years of college for all students who scored at or above T = 60 on both MMPI scales (N = 83) were compared with rates for all other students (N = 269). Students in the high Depression-Psychasthenia group were significantly more likely to seek counseling during their freshman years than were other students (p less than .05). Among counselees the high MMPI group also made significantly more visits to the service (p less than .05). Application of a Bayesian rule disclosed that the MMPI measure would have improved decision accuracy only with respect to the prediction that a student would come in for counseling at some time during college. In this population, the MMPI measure is both a valid and a useful predictor.

Counseling↗
PubMed1977

Continuing education in the community hospital: an interprofessional approach.

The need for continuing medical education has been growing over the past decade but is largely unmet by, and within, most community hospitals. In this paper the author outlines the development of a systematic, interprofessional, self-directed approach to postgraduate education with a local community hospital. Also described is the format followed in assessing educational needs, evaluating resources, and initiating appropriate and necessary programs. Although care must be taken to avoid too much interdisciplinary involvement solely for the sake of the concept itself, the interprofessional model would appear to meet most educational needs, both individually and collectively, at the community hospital level.

Education, Medical, Continuing↗
PubMed1976

Normal rate of cerebrospinal fluid formation five years after bilateral choroid plexectomy. Case report.

A ventricular perfusion technique was used to determine the rate of cerebrospinal fluid (CSF) formation in a 5-year-old child who had undergone bilateral choroid plexectomy for communicating hydrocephalus during infancy. At the time of the study, the patient had a failed ventriculoperitoneal shunt and was suffering from progressive ventriculomegaly. The calculated rate of CSF formation, 0.35 ml/min +/- 0.02 standard deviation, was within normal limits.

Cerebral Ventriculography↗
PubMed1976

Choroid plexus papilloma. I. Proof of cerebrospinal fluid overproduction.

Utilizing a ventricular perfusion technique, the rate of CSF formation was determined in a 2-year-old child before and after removal of a 74 g choroid plexus papilloma from the left lateral ventricle. Preoperatively, the CSF formation rate was 1.05 +/- SD 0.01 ml/min (1,656 ml/day). Postoperatively, the CSF formation rate was reduced fivefold to 0.20 +/- SD 0.01 ml/min (288 ml/day). Whereas these data are regarded as conclusive evidence of CSF overproduction by a choroid plexus papilloma, the pathogenesis of generalized ventricular enlargement in this case was due to part to obstruction of the subarachnoid pathways.

Cerebral Ventricle Neoplasms↗
PubMed1976

A 4-channel telemetry system for hospital patient monitoring.

A 4-channel radio telemetry system has been designed and implemented for use in the operating room on patients undergoing surgery. 30 such systems are in daily use throughout the Duke University Medical Cener. Relative simplicity, long battery life and a DC-response capability are the important features of these systems. The four physiological channels used are; electroencephalogram, electrocardiogram, peripheral pulse, and arterial blood pressure.

Blood Pressure Determination↗
PubMed1976

Choroid plexus papilloma. II. Ultrastructure and ultracytochemical localization of Na-K-ATPase.

An electron-microscopic study of a choroid plexus papilloma from the lateral ventricle of a child revealed fine structural features typical of normal choroid plexus tissue. Utilizing the Ernst technique for demonstrating ouabain-sensitive, potassium-dependent phosphatase activity, Na-K-ATPase was localized along the basal and lateral plasmalemmas of the tumor epithelium but not along the ventricular surface (apical plasmalemma). This localization is similar to that found in normal choroid plexus epithelium of all species studied to date.

Adenosine Triphosphatases↗
PubMed1975

Globid leukodystrophy. II. Ultrastructure and chemical pathology.

A chemical-pathoologic study of globoid leukodystrophy (GLD) was made that compared myelin isolated from maximally involved central white matter with myelin from noninvolved U fiber areas. The results were compared to analyses of myelin from normal, age-matched control human brains. Myelin from U fiber areas contained relatively greater amounts of a lighter myelin fraction and this lighter myelin differed in protein and lipid composition from the heavier myelin fraction. The data have been interpreted to suggest that the metabolic error in GLD results in the formation of an unstable compact or heavier myelin and that a subsequent process of disintegration selectively affects this component.

Brain↗
PubMed1975

The blood-brain barrier of the rat choroid plexus.

Following intravenous injection, cytochrome c traverses the capillary endothelium of the rat choroid plexus and permeates the perivascular space and the extracellular space between epithelial cells. The tracer is incorporated into pinocytotic vesicles adjacent to the lateral and basal plasmalemmas. Thereafter, cytochrome c is incorporated into multivesicular and dense bodies. Tracerladen vesicles were not found to fuse with the apical plasmalemma and cytochrome c was not discharged into the cerebral ventricles. Acid phosphatase activity of the choroidal epithelium after the administration of cytochrome c was greatly increased and localized in the same intracellular sites shown for cytochrome c. These data suggest that cytochrome c and possibly other proteins that penetrate the choroidal stroma are taken up by the choroidal epithelium and subsequently degraded in lysosomal vesicles. This heterolytic mechanism may be an important means for preventing the entry of certain substances such as proteins into CSF and subsequently into nervous tissue.

Acid Phosphatase↗
PubMed1975

Clinical aspects of bilateral renal dysplasia in children.

Despite recent attempts to improve classification and to provide data on pathogenic mechanisms, there is a paucity of information concerning the clinical aspects of bilateral renal dysplasia. Therefore, the clinical features and long-term prognosis of eight patients with bilateral renal dysplasia have been evaluated. Three important observations were made, namely (1) a large proportion of patients had an impairment of urinary concentration and acidification, (2) the clinical course was characterized by progressive renal deterioration in patients with bilateral involvement, and (3) four children with renal dysplasia had the clinical features of Laurence-Moon-Biedl syndrome.

Adolescent↗
PubMed1975

Experimental intracerebral movement of electron microscopic tracers of various molecular sizes.

The authors demonstrate that, while the intracerebral movement of proteins and other relatively large molecules is restricted by tight junctions of endothelia and epithelia of the brain, calcium ion penetrates these barriers and moves between the blood and CSF cavities by extracellular pathways. Mechanisms underlying CSF formation are considered on the basis of this anatomical continuity of the vascular, extracellular, and CSF compartments of the brain for very small molecules.

Acid Phosphatase↗