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Biomedical subjects

S K Wolfson

Publications and source records attributed to S K Wolfson.

16 recordsLinked to original sources
PubMed1979

Comparative cranial CT enhancement in a primate model of cerebral infarction.

The value of various enhancement techniques as opposed to nonenhanced CT scanning was compared in 15 baboons with cerebral infarction secondary to embolization of the left middle cerebral artery. The most prominent CT findings in infarction included an area of low absorption in the opercula--basal ganglia--centrum semiovale region and generalized lateral ventricular enlargement. Intravenous enhancement of the low-density region occurred in 25% of the animals and often obscured the preenhancement abnormality. However, a rapid bolus injection of contrast material followed by immediate consecutive CT scans (computed angiotomography) permitted prominent visualization of early-shunting veins. Delayed scanning following intrathecal enhancement better defined small infarctions that did not exhibit the usual cerebral blush. The CT imaging of inhaled xenon provides a new technique for evaluating subtle abnormalities in cerebral perfusion, even when the routine CT scan shows no abnormality.

Animals↗
PubMed1979

Immobilized enzyme electrodes for the potentiometric measurement of glucose concentration: immobilization techniques and materials.

Glucose oxidase, catalase, and bovine serum albumin were co-immobilized with glutaraldehyde around a platinum screen or around a single platinum-iridium wire. The potential difference between this dual enzyme electrode and a Ag/AgCL reference electrode was proportional to the logarithm of the glucose concentration over the range from 10 to about 150 mg glucose per 100 ml in buffered solution at pH 7.4 and 37 degrees C. The enzyme electrode responded in serum only if coated with a semipermeable film, such as cellulose acetate, to exclude serum macromolecules. The potentiometric results were similar to those obtained with the two enzymes co-immobilized in polyacrylamide gel around a platinum screen or with only one of the enzymes, glucose oxidase, covalently coupled to a platinum screen. The results so far suggest that glucose for development of a continuous in vivo glucose sensor.

Catalase↗
PubMed1979

Patterns of brain perfusion: dynamic computed tomography using intravenous contrast enhancement.

A representation of cerebral perfusion is obtained using cranial computed tomography following the rapid bolus injection of iodinated intravenous contrast medium. This technique permits the definition of four gross patterns of perfusion (normal, circulatory arrest, hypoperfusion, and hyperperfusion). This classification is affirmed in an experimental model of cerebral infarction in the baboon. The limitations of dynamic imaging using computed tomography are reviewed.

Animals↗
PubMed1979

Dynamic computed tomography of the lung: regional ventilation measurements.

The spatial resolution provided by computed tomography (CT) yields excellent anatomic specificity, and fast scanners are capable of the serial imaging necessary to monitor rapid changes in tracer concentration over time. In this study, sequential CT imaging defined the temporal changes of xenon concentration in peripheral lung tissue of a nonhuman primate and three sheep, both during and after xenon inhalation. Ventilation rate constants (K) in lung tissue with normal and impaired function in the evaluation of regional ventilation using xenon enhanced CT are discussed.

Animals↗
PubMed1978

Physiologic changes in regional cerebral blood flow defined by xenon-enhanced CT scanning.

With adequate concentrations of commercially available nonradioactive xenon an enhancement of brain substance was readily demonstrated by computed tomography (CT). By performing successive CT scans at a fixed brain level following xenon inhalation, the partition coefficient and clearance of xenon as well as the regional cerebral blood flow (rCBF) could be calculated. The expected physiologic alterations in rCBF with acute cerebral infarction and changes in arterial CO2 were accurately defined by xenon-enhanced CT scanning affirming the potential future applications of this technique.

Animals↗
PubMed1977

Ophthalmologic applications of computed tomography in nonhuman primates.

The orbital contents of 28 baboons are defined by computed tomography (CT), which provides a simple, reliable, reproducible, and accurate technique for the experimental investigation of the orbit of the nonhuman primate. This method is applied to the diagnosis of exophthalmos. The suprasellar and other basal subarachnoid cisterns are precisely delineated using intrathecal enhancement prior to CT imaging (metrizamide CT cisternography).

Animals↗
PubMed1977

The capacity for computed tomography diagnosis of cerebral infarction. An experimental study in the nonhuman primate.

The characteristic serial CT scan appearance of cerebral infarction created by embolization of the middle cerebral artery in the nonhuman primate (10 baboons) is defined. The earliest CT changes are noted by 12 to 24 hours and include generalized ventricular enlargement and a focal region of decreased absorption in the opercula-basal ganglia region. The area of diminished brain absorption is better circumscribed and of lower attenuation coefficient with increasing chronicity. Distinct hydrocephalus, unilateral exophthalmos and ventricular displacement occurred with increased intracranial pressure. Little additional diagnostic information was obtained via intravenous enhancement and care should be taken as mild enhancement may obscure an area of abnormality.

Animals↗
PubMed1977

Cranial computed tomography in the baboon: normal anatomy.

A simple, reliable, reproducible technique for performing CT scans on baboons is described. The normal morphologic appearance in 12 nonhuman primate (Papio cynocephalusl anubis) brains as defined by CT is correlated with the normal gross pathologic findings on postmortem examination. The orbital contents are also displayed with clarity equivalent to that obtained in man.

Animals↗
PubMed1976

Materials for selective tissue heating in a radiofrequency electromagnetic field for the combined chemothermal treatment of brain tumors.

A technique of creating localized heating by implanting metallic materials in the brain and inserting the head into a radiofrequency electromagnetic field is described. The heating properties of various materials for implantation were studied, and the two best materials were carbon steel rods and Hysterloy (1000 and 655 cal/g-min, respectively). Heating of these materials was done primarily by eddy current since their heating rates were significantly affected by their shapes and orientation in the field, rods oriented parallel to the field producing the most heat. There is evidence that warmer cells have a greater uptake of chemotherapeutic agents. This suggests a combined therapeutic approach employing localized brain heating in conjunction with systemic or intrathecal chemotherapy. In this way, large doses of chemotherapeutic drugs might be concentrated in a warmed brain tumor while toxicity is prevented by keeping the rest of the brain and body hypothermic.

Alloys↗
PubMed1976

Spontaneously occurring agglutinins in primate sera.

Tests for spontaneously occurring agglutinins in the sera of nonhuman primates showed that such antibodies are not infrequent. Some act as heteroagglutinins, others as autoagglutinins, while of most interest are the isoagglutinins, especially those found in female animals apparently resulting from isoimmunization in pregnancy.

Agglutinins↗
PubMed1976

Preferential cerebral hypothermia with elective cardiac arrest: resection of "giant" aneurysm.

The technique of preferential cerebral hypothermia is reported in its application to a patient with a "giant" anterior communicating artery aneurysm. The method utilizes elective ventricular fibrillation and differential or "preferential" hypothermia induced by a combination of external skin cooling and perfusion of core organs with 0 degree buffered electrolyte solution. The value of the technique lies in its provision of a period of safe circulatory arrest approaching one hour without the need for anticoagulation, heart-lung bypass, open chest resuscitation or major vessel clamping. Because of the absence of blood flow and because of the clear fluid washout of the cerebral vessels, it was possible to open the aneurysm, evacuate its contents and resect it in several sections. It was not necessary to clip the feeding arteries until all dissection and total removal of the aneurysm were completed. The application of the technique to neurosurgery and cardiovascular surgery is discussed.

Heart Arrest, Induced↗
PubMed1975

Biochemical values in the normal and hypothermic baboom Papio cynocephalus/anubis.

Seventeen biochemical parameters were measured in the venous and arterial blood of normal adolescent baboons (P. cynocephalus/anubis) under normothermic sedation and normothermic and hypothermic anesthesia. Statistical comparisons of the results were made between sexes and between the two temperatures under anesthesia. Six parameters differed significantly between males and females and five varied significantly between normothermia and hypothermia. Comparisons to the existing literature and the differences under hypothermia are briefly discussed.

Anesthesia, Inhalation↗
PubMedDate not supplied

Comparative cranial CT enhancement in the normal primate.

The application of intravenous, intrathecal, and inhalation enhancement techniques to the CT evaluation of the nonhuman primate (Papio cynocephalus/anubis) is described. The falx cerebri cortical vasculature, vein of Galen, straight sinus and tentorium cerebelli were defined with intravenous enhancement. Intrathecal CT enhancement with air was limited by distortion in cerebrospinal fluid spaces. Intrathecal CT enhancement using a low dose of metrizamide accurately delineated the subarachnoid spaces and the brain substance they surrounded with minimal morbidity. Symmetrical brain enhancement (perfusion) was prominent following inhalation CT enhancement; the degree of enhancement correlated with the estimated xenon concentration in the bloodstream. In addition, by performing repeated CT scans during the clearance of xenon from the brain, an approximate analysis of regional cerebral blood flow was obtained.

Animals↗
PubMedDate not supplied

Xenon enhanced CT for analysis of cerebral integrity, perfusion, and blood flow.

Enhancement of the brain substance for CT evaluation using inhaled Xenon is confirmed. This technique was applied to the study of the normal and the embolized adolescent baboon. Healthy cerebral tissue enhances symmetrically, while abnormal areas show significantly diminished enhancement. At maximal enhancement, an indication of gross comparative cerebral perfusion to obtained. By obtaining serial CT scans over a 10 minute time interval, the clearance rate of Xenon (cerebral blood flow) may be evaluated. Xenon-enhanced CT enables a visual and numerical analysis of both brain morphology and physiology.

Animals↗