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Biomedical subjects

W Levy

Publications and source records attributed to W Levy.

18 recordsLinked to original sources
PubMed1990

The radiotherapeutic management of chordoid sarcoma.

Chordoid sarcoma is a rare neoplasm, with only 13 cases reported. In the past, the treatment of choice was excision or amputation, with radiation therapy reserved for metastases. This case report demonstrates the persistent nature and indolent course the tumor may have and its good response to high-dose irradiation. External beam irradiation, both photons and electrons, intraoperative radiation therapy, and 192-iridium implantation have all been successfully utilized for treatment of multiple recurrences in this patient. Doses of 6,000 cGy or greater were necessary to control the tumor in our patient, and this dose is recommended as adjuvant treatment following conservative (gross) tumor removal.

Brachytherapy↗
PubMed1990

Reperfusion hyperoxia in brain after circulatory arrest in humans.

Changes in the electroencephalogram (EEG), mean arterial blood pressure (MABP), and hemoglobin saturation in brain vasculature of lightly anesthetized normothermic humans undergoing induced circulatory arrest for implantation of an automatic internal cardioverting defibrillator were studied. EEG was measured using a four-channel bipolar montage and hemoglobin saturation was measured transcranially using reflectance spectroscopy at 760 nm with an isosbestic reference at 800 nm. Hemoglobin saturation of blood in the quadriceps muscle was also measured. Thirty-two episodes of hypotension due to ventricular fibrillation were studied along with 31 episodes of hypotension related to ventricular tachycardia and rapid ventricular pacing. In a typical fibrillatory event there was a decrease in MABP followed almost immediately by changes in hemoglobin saturation of blood in the brain vasculature. The first changes in EEG were detected an average of 6.5 s (P less than 0.001, paired t test) after the beginning of change of brain vascular hemoglobin. In some cases changes in hemoglobin saturation could be detected without changes in EEG. Desaturation curves from muscle and brain were significantly different, suggesting that the brain probe was measuring hemoglobin change in a rapidly metabolizing volume of tissue that was dissimilar to the skin, muscle, and bone monitored by the probe over the quadriceps muscle. Examination of the 32 episodes of circulatory arrest revealed a marked response that began immediately with recirculation characterized by an increase of the hemoglobin saturation signal from brain vasculature to above baseline as the duration of circulatory arrest exceeded 37 s, this response is termed reperfusion hyperoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Comparison of time-resolved and -unresolved measurements of deoxyhemoglobin in brain.

Continuous (CW) and pulsed light were used for the noninvasive measurement of hemoglobin oxygenation in tissues. A dual wavelength method of continuous illumination spectroscopy used 760 nm (deoxyhemoglobin peak) and 800 nm (an oxyhemoglobin-deoxyhemoglobin isosbestic point) to measure the kinetics and extent of oxyhemoglobin deoxygenation in brains during mild ischemia/hypoxia. Absorption and scattering were modeled in an artificial milk/yeast blood system, which gave an exponential relationship between absorption and optical path length to a depth of 7 cm. Time-resolved spectroscopy (10-ps resolution) afforded a display of the times and distances of arrival of photons emitted by the cat brain in response to a 10-ps input pulse. The emitted photons rose to a peak in a fraction of a nanosecond and declined exponentially over a few nanoseconds. The half-time of exponential decay corresponds to photon migration over a distance of 4 cm. Exponential light emission continued for several more nanoseconds when the brain was encased by the skull, which plays a key role in prolonging light emission. The exponential decline of light intensity has a value [exp(-microL)], where L is the path length determined from the time/distance scale and mu is the characteristic of the migration of light in the brain. The factor mu is increased by increasing absorption, and mu' = epsilon C where epsilon and C are the Beer-Lambert parameters of extinction coefficient (epsilon) and concentration (C). Thus, deoxyhemoglobin can be quantified in brain tissues.

Animals↗
PubMed1988

Ovarian function following marrow transplantation for aplastic anemia or leukemia.

One hundred eighty-seven women between 13 and 49 years of age had ovarian function evaluated from 1 to 15 years (median, 4) after marrow transplant for aplastic anemia or leukemia. Among 43 women transplanted for aplastic anemia following 200 mg/kg cyclophosphamide (CY), all 27 less than 26 years of age, but only five of 16 greater than 26 years of age recovered normal ovarian function. Nine of the 43 have had 12 pregnancies, resulting in eight live births, and two elective and two spontaneous abortions. All eight children are normal. Nine of 144 women transplanted for leukemia following 120 mg/kg CY and 9.20 to 15.75 Gy total body irradiation (TBI) recovered ovarian function. Two of these nine have had three pregnancies, resulting in two spontaneous and one elective abortion. The probability of having ovarian failure was 0.35 by 7 years for patients receiving CY alone and was 1.00 at 1 year for patients receiving CY plus TBI (P less than .0001). By 7 years after transplant the probabilities of having normal ovarian function were 0.92 after CY alone and 0.24 after CY plus TBI (P less than .0001). Multivariate analysis showed that TBI was the only factor significantly influencing ovarian failure and that both TBI and greater patient age at transplant were significantly associated with a decreased probability of recovering normal ovarian function. These data demonstrate that after high-dose CY, recovery of ovarian function occurs in younger women and in a minority of older women, but after CY and TBI, recovery occurs in only a few younger women and none of the older women.

Adolescent↗
PubMed1988

Long term administration of prostaglandin inhibitors in vivo fail to influence cartilage and bone mineral metabolism in the rat.

Non-steroidal anti-inflammatory drugs are potent inhibitors of prostaglandin synthesis. Prostaglandins have been reported to stimulate bone resorption and to enhance 1,25(OH)2D3 production in vitro. In patients with osteoarthritis of the hip, non-steroidal anti-inflammatory drugs are associated with localized accelerated bone destruction. The mechanisms for some of the in vivo effects are unknown. The effects of prostaglandin inhibitors on normal bone and mineral homeostasis has not been established. Therefore 15 male Sprague-Dawley rats were given daily injections of indomethacin, 2 mg/kg s.c., for either 4 or 8 weeks (a dose known to inhibit fracture healing) and compared to 13 control rats given vehicle alone. Serum Ca, BGP and 1,25(OH)2D were measured serially until day 56 in nine of those administered indomethacin and in seven of the control animals. Bone histomorphometry with double tetracycline labelling and cartilage histology were performed after sacrifice on days 28 and 56. Compared to control animals serum ionized calcium, BGP and 1,25(OH)2D levels were not altered by indomethacin administration. Quantitative histomorphometric indices of bone formation and resorption as well as cartilage histology were not significantly different between the two groups. With time, however, serum bone Gla protein fell in the control and indomethacin-treated groups, while calcium and 1,25-dihydroxyvitamin D remained stable. The age related decline in this serum marker of bone turnover was accompanied by a parallel reduction in the level of bone remodelling activity. These reductions in bone formation and bone resorption were not retarded or enhanced by indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Experience with marrow harvesting from donors less than two years of age.

Experience in harvesting marrow for allogeneic marrow transplantation from 23 infant donors is presented. Ten donors were less than one year of age and 13 were between one and two years of age at the time of initial donation. None of these donors experienced major difficulties following the aspiration procedure. Three donors had significant medical problems diagnosed during the pre-donation evaluation. All aspirations were performed from iliac crests and all donors were given general anesthesia. Irradiated blood bank transfusions were given to 85% of the donors during the procedure. The volume of marrow obtained ranged from 11.5 to 19.3 ml/kg donor weight and contained from 2.5 to 10.4 x 10(8) nucleated cells/kg donor weight. Thus, very young children may safely donate marrow for allogeneic transplantation and the nucleated cell count obtained is substantial.

Age Factors↗
PubMed1986

Motor evoked potential in cats with acute spinal cord injury.

We have previously reported that a motor evoked potential (MEP) can be produced by transcranial stimulation of the motor cortex in cats and humans. This signal travels in both dorsolateral and ventral spinal cord. We report here the evaluation of this evoked potential in comparison to the somatosensory evoked potential (SEP) in an acute spinal cord weight drop model. In all animals, the peripheral nerve signal was the component of the MEP most sensitive to injury. Often, it was significantly reduced in amplitude by incidental manipulation of the spinal cord during a careful laminectomy and then returned. It was lost first in animals with weight drop spinal cord injury and was abolished with as little as 50 to 75 g/cm of force. The spinal cord signal of the MEP was consistently more sensitive to injury than the SEP and was abolished at about 100 to 150 g/cm of impact. The cortical SEP was abolished at about 200 to 250 g/cm, and the spinal cord SEP was abolished at similar levels. The SEP returned earlier after injury than the MEP. Anesthetic agents had an effect on the MEP in the spinal cord and substantially changed the peripheral nerve signal, in both wave form shape and optimal stimulation frequency. Marginal cord injury and abnormal metabolic conditions caused the peripheral nerve signal to decrement in amplitude with increasing trial numbers during a run and become unstable. These latter effects need further characterization and are critical guides to investigative and clinical use of this test. This study indicates that the MEP is more sensitive than the SEP in detecting spinal cord injury.

Animals↗
PubMed1985

Hypothalamic dysfunction in overtrained athletes.

Some athletes who undertake strenuous training programs for a prolonged period of time develop the overtraining syndrome. The pathophysiology of the condition is unknown. Hypothalamic-pituitary function was studied by determining the hormonal responses to insulin-induced hypoglycemia in five asymptomatic male marathon runners during a 4-month period in which they ran 42-, 56-, and 92-km races and in four overtrained male athletes. The response of the asymptomatic runners was not different when tested 1 month before and within 48 h after the 42- and 92-km races. All four overtrained athletes presented with impaired training and racing times, apathy, and a heavy-legged feeling and were tested when overtrained and again after 4 weeks of rest. The plasma cortisol, ACTH, GH, and PRL responses to insulin-induced hypoglycemia in the four overtrained athletes were lower than their responses after the rest and lower than the responses of the asymptomatic runners. In both groups, the LH, TSH, and PRL responses to LHRH and TRH were normal. The impaired hormonal responses to insulin-induced hypoglycemia, with recovery after 4 weeks of rest, indicate hypothalamic dysfunction and may be a diagnostic marker of the overtraining syndrome.

Adrenocorticotropic Hormone↗
PubMed1976

The short- and long-term prognosis of patients with transmural and nontransmural myocardial infarction.

To compare the long-term prognosis in patients surviving transmural with patients surviving nontransmural myocardial infarctions, the records of 188 consecutive patients with clinical histories and enzyme elevations consistent with acute infarction were reviewed. According to standard electrocardiographic criteria the patients were divided into two groups: 148 with transmural myocardial infarction (group 1) and 40 with nontransmural myocardial infarction (group 2). Of the patients who survived hospitalization, follow-up data were obtained on 119 of 124 patients in group 1 and 36 of 37 patients in group 2 at a mean follow-up period of 36 months. In group 2, the patients had a high incidence of sudden death after discharge (33 per cent in group 2 versus 15 per cent in group 1, p less than 0.02) as well as a significantly higher incidence of death from all cardiac causes (41.6 per cent in group 2 versus 24.3 per cent in group 1, p less than 0.05). Furthermore, the patients in group 2 still alive at the end of the follow-up period had an increased incidence of angina pectoris and of recurrent infarction. The data suggest that patients with nontransmural myocardial infarction carry a particularly guarded prognosis.

Connecticut↗