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Biomedical subjects

W Feindel

Publications and source records attributed to W Feindel.

At least 73 records · Page 4Linked to original sources
PubMed1984

Evaluation of [18F]-4-fluoroantipyrine as a new blood flow tracer for multiradionuclide autoradiography.

This article reports the evaluation of [18F]-4- fluoroantipyrine (FAP) as a quantitative blood flow tracer by comparing blood flow measured with [18F]FAP to that determined simultaneously with [14C]-4-iodoantipyrine (IAP), a standard blood flow tracer, by means of double-tracer autoradiography. The single-pass extraction value (m), which indicates diffusibility of a tracer, was determined according to the procedure described by Crone . The diffusibility of FAP was essentially the same as that of IAP. The brain-blood partition coefficient for FAP was found to be similar to that for IAP, 0.89 +/- 0.01. Values of local cerebral blood flow obtained with FAP agree with those determined with IAP. From these results, we concluded that FAP is indeed as good a blood flow tracer as IAP. Since 18F is a positron-emitting radionuclide, it might be a useful tracer for blood flow measurement by positron emission tomography.

Animals↗
PubMed1984

An improved approach for measurement of regional cerebral rate constants in the deoxyglucose method with positron emission tomography.

A new experimental approach was designed to measure regional rate constants for [18F]2-fluoro-2-D-deoxyglucose in the three-compartment model. A programmed infusion was used to keep the plasma tracer concentration constant for the first 20 min. Positron emission tomography images of the brain were taken every minute for 20 min in a low-resolution mode, then every 15-20 min for 2-3 h in a medium-resolution mode. Two simplified operational equations for the calculation of the regional rate constants were derived that incorporated the contribution of the vascular compartment to tissue activity. The first equation was applied to data collected during the initial 20 min (when the concentration of plasma tracer was constant) to estimate the values of k1*, k2*, k3*, and the fraction of the vascular compartment. The second equation was applied to data collected during the whole experimental period to find the value of k4* and to provide a better estimate of k3*. The regional rate constants measured experimentally in three dogs and a brain tumor patient agreed well with those in the literature. This method permits estimation of the local CMRglu under pathological conditions using regionally measured rate constants and provides new information on the pathophysiological meaning of the rate constants.

Aged↗
PubMed1984

Pharmacokinetics of positron-labeled 1,3-bis(2-chloroethyl)nitrosourea in human brain tumors using positron emission tomography.

The nitrosoureas are widely used in the chemotherapy of brain tumors, two of the most common being 1,3-bis(2-chloroethyl)nitrosourea and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea. However, we do not understand how these compounds work, nor do we know which part of the molecule has antitumor activity. In six patients with brain tumor, we measured the kinetic behavior of positron-labeled 1,3-bis(2-chloroethyl)nitrosourea in both the tumor and the normal brain with the aid of positron emission tomography; we also analyzed the distribution of radioactivity in plasma. We found the clearance of total radioactivity from the tumor to be significantly slower than from the contralateral brain and plasma, indicating a different rate of 1,3-bis(2-chloroethyl)nitrosourea decomposition in the tumor than in normal brain.

Brain Neoplasms↗
PubMed1983

Epilepsy from cerebral arteriovenous malformations.

Twenty-seven patients with epilepsy as the only manifestation of a cerebral AVM were seen at the MNI/MNH from 1973 to 1981. The nine females and eighteen males between the ages of fourteen and fifty-four years (mean 25.2 years) had epilepsy for an average of 3.5 years prior to the diagnosis of AVM. Seven patients had primarily generalized seizures, ten patients had partial seizures with complex symptoms, fourteen patients had partial seizures with elementary symptoms, and thirteen patients had secondarily generalized seizures. Although there was no history of intracranial hemorrhage, seven patients had negative hemispheric signs (hemiatrophy, hemianopia, dysphasia, hemiparesis), two had impaired mentation, and two were ataxic. The EEG, normal in ten cases,showed non-epileptiform activity in six cases, and focal epileptiform activity in eleven cases. Angiographic and/or histological examination revealed eight small (less than 2 cm in diameter) and nineteen large lesions. Fifteen AVMs involved the frontal lobe, ten the temporal lobe five the parietal lobe, and one the occipital lobe. Angiography failed to demonstrate three frontal and three temporal AVMs. Plain CT scanning demonstrated a high or low density lesion without a mass effect in sixteen cases, enlargement of the ipsilateral ventricle or Sylvian fissure in seven cases, and diffuse ventricular enlargement in three cases. CT scanning was performed after the intravenous injection of contrast material in nineteen cases and demonstrated vascular enhancement in fifteen cases and an abnormal blood vessel in six cases. Two angiographically occult AVMs demonstrated vascular enhancement with infusion CT scanning, thereby demonstrating the vascular nature of the lesion where angiography had failed to do so.

Adolescent↗
PubMed1983

An on-line synthesis of [15O]N2O: new blood-flow tracer for PET imaging.

This paper describes a recently developed on-line synthesis of a new blood-flow tracer, O-15-labeled nitrous oxide. The tracer was produced by catalytic oxidation of anhydrous ammonia in a gas mixture containing O-15-labeled molecular oxygen. (The oxygen-15 was produced by a 14N(d,n)15O reaction.) Anhydrous ammonia was mixed with the gas containing [15O]O2, and after preheating to about 200 degrees C was carried through an oven containing a Pt catalyst kept at about 310 degrees C. Labeled gas was purified in H3PO4 and KOH traps. O-15-labeled nitrous oxide was identified by gas radiochromatography and by various chemical reactions. Radiochemical purity of the O-15-labeled nitrous oxide exceeded 98%, radiochemical yield corrected for radioactioactive decay was 15-20%, and specific activity at the end of synthesis was about 50 mCi/mmole.

Nitrous Oxide↗
PubMed1983

[Effect of dexamethasone on tumorous brain edema--changes in regional cerebral blood flow and glucose utilization].

An experimental brain tumor was produced by implanting a piece of A.A. ascites tumor into the parietal brain of rat. Local cerebral blood flow (LCBF) and glucose utilization (LCGU) were determined in this model with 14C-iodoantipyrine and 14C-deoxyglucose quantitative autoradiographic methods, respectively, to investigate the change of blood flow and glucose metabolism and the effect of dexamethasone in the brain with tumor. LCBF and LCGU in the peritumoral brain tissue were reduced 75% and 60%, respectively, compared with the values of the control. In the ipsilateral frontal and occipital cortical areas far from the tumor, 50% and 45% reduction of LCBF, respectively, was observed. More than 30% reduction of LCGU was seen in the same areas. In the caudate and corpus callosum ipsilateral to the tumor, LCBF was diminished 25% and 40%, respectively. LCGU was not significantly changed in these areas. No significant changes of LCBF and LCGU were observed in the contralateral hemisphere. In the dexamethasone-treated animal, the reduction of LCBF was less in all areas where it was reduced in the untreated animal. In the peritumoral brain tissue, LCBF was significantly higher compared to that of the untreated group, and 80% of the normal level. In the ipsilateral frontal and occipital cortical areas, caudate and corpus callosum, LCBF was about the same as that of the control group. In the animal treated with dexamethasone, quantitative analysis of LCGU could not be made because of high glucose levels in plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

The contributions of Wilder Penfield to the functional anatomy of the human brain.

Wilder Penfield's early studies with Sherrington, Hortega and Foerster led to his life-long studies on the surgical treatment of focal epilepsy. Working with a succession of neurosurgical associates, Penfield contributed a continuing stream of observations on responses of the human cerebral cortex to electrical stimulation. These characterized the detailed topographical distribution of the primary and secondary sensory and motor areas, and the representation of language function in the inferior frontal, superior frontal and temporo-parietal cortex. He defined the role of the hippocampi and the lateral temporal cortex in memory. From these findings, he postulated the centrencephalic integrating system, as a basis for explaining diffuse bilateral seizure activity, and the mechanism of consciousness.

Brain↗
PubMed1980

Impressions of neurology and neurosurgery in the People's Republic of China.

During July, 1979, the authors visited the neurological and neurosurgical services of eight major hospitals and associated medical schools in Peking, Tientsin, and Shanghai, and viewed many of their teaching and research facilities. From these visits and our discussions with the staffs of these units, we came away with the impressions reported here. In the People's Republic of China today there are more than 2,000 neurologists and 1,300 neurosurgeons. At present there are two major clinical centers: the Peking Institute of Neurosurgery, directed by Prof Wang Chung-Cheng and located in the Xuan Wu Hospital affiliated with the Peking First Medical College; and the Shanghai Institute of Neurology, directed by Prof Chang Yuan-Cheng and located in the Hua San Hospital affiliated with the Shanghai First Medical College. In every hospital, patient loads are formidable (e.g., several thousand outpatients weekly), but the variety of clinical problems does not differ from those seen elsewhere in the world. The most common problems are head injuries, brain tumors, cerebrovascular disorders, infections, and epilepsy. Each of the centers is heavily engaged in undergraduate and postgraduate training, and research has been resumed after the major disruptions of the 1966-76 "Cultural Revolution." Research continues on acupuncture, but present emphasis is directed toward pain mechanisms, notably at the Shanghai Institute of Physiology, directed by Prof Feng De-Pei. We were most impressed by this, the principal neurophysiology and neuroscience research center in the country. Clearly, the People's Republic of China has a wealth of clinical material and many competent neurologists and neurosurgeons with stimulating research ideas-characteristics which offer real potentials for collaborative research.

Acupuncture Therapy↗
PubMed1979

Superficial temporal artery to middle cerebral artery anastomosis. Intraoperative evaluation by fluorescein angiography and xenon-133 clearance.

Fluorescein angiography and xenon-133 (133Xe) clearance studies were performed during surgery on 15 patients who were undergoing superficial temporal artery (STA) to middle cerebral artery (MCA) anastomosis. Fourteen patients had occlusive disease of the internal carotid artery (ICA), and one patient had severe stenosis of the MCA. Before anastomosis, fluorescein angiography showed slow filling of the MCA branches through collateral channels. Focal areas of impaired microcirculatory filling and washout were seen in the territory of severely sclerotic cortical arteries. The findings of preanastomotic 133Xe clearance studies were variable and a uniform pattern of regional cerebral blood flow (rCBF) changes was not defined. In 55% of the patients, rCBF was reduced to 25 ml/100 gm/min or less at one or more detector sites. Fluorescein angiography provided an immediate assessment of anastomotic patency and clearly displayed the distribution of blood entering the epicerebral circulation through the STA. In 67% of patients, multiple MCA cortical branches filled with fluorescein, whereas in 33% filling was restricted to the receptor artery territory. An immediate, substantial (greater than or equal to 15 ml/100 gm/min) increase in rCBF was demonstrated in 73% of patients after anastomosis. The rCBF changes were consistently better in patients with donor and receptor arteries greater than 1 mm in diameter. Redistribution of collateral input acted to increase rCBF in areas distant from the anastomotic site. Some improvement in fluorescein circulation and rCBF also was seen in cortex supplied by sclerotic MCA branches.

Adolescent↗