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Biomedical subjects

D A Rottenberg

Publications and source records attributed to D A Rottenberg.

At least 91 records · Page 5Linked to original sources
PubMed1977

Cerebral necrosis following radiotherapy of extracranial neoplasms.

We have examined 6 patients with delayed cerebral necrosis following irradiation of extracranial neoplasms. Four of the 6 patients received 1,760 rets (or less) tumor dose. The initial symptoms attributable to radiation necrosis appeared 4 to 31 months after irradiation and were those of a focal supratentorial mass. Cerebral angiography delineated an avascular frontal or temporal lesion in all 6 patients; in 1 case a magnification study revealed narrowing, irregularity, and occlusion of small cortical vessels. Four of our 6 patients underwent craniotomy with partial or complete surgical extirpation of necrotic brain tissue. Two operated patients are alive and without disabling neurological symptoms 30 and 25 months, respectively, after the operation. The characteristic neuropathological features of delayed radiation necrosis of brain suggest that vascular injury rather than neuronal or glial damage is of primary pathogenetic significance.

Adult↗
PubMed1977

The rate of CSF formation in man: preliminary observations on metrizamide washout as a measure of CSF bulk flow.

Metrizamide, a nonionic, water-soluble contrast agent, was injected into the ventricular system of 3 patients with indwelling ventricular catheters and subcutaneous cerebrospinal fluid reservoirs. A first-order rate constant, k, for metrizamide washout from the right lateral ventricle was determined with reference to mean ventricular metrizamide concentration on serial CAT scans; right ventricular volume, V, was estimated after metrizamide injection by multiplying the appropriate ventricular area on consecutive CAT slices by the nominal slice thickness. The rate of right lateral ventricular CSF formation, If, in our 3 patients was calculated as k X V and ranged from 0.083 to 0.103 ml per minute.

Adult↗
PubMed1977

Painful tic convulsif.

Painful tic convulsif is a syndrome restricted to paroxysmal dysfunction of the fifth and seventh cranial nerves. It occurs primarily in women over the age of 50 years and is usually associated with an ectatic vertebrobasilar artery--less frequently an arteriovenous malformation or cholesteatoma--which compresses the trigeminal and facial nerve roots in the posterior fossa. In rare instances this syndrome may be caused by disseminated sclerosis. Because of the high incidence of posterior fossa lesions in painful tic convulsif, a complete neurological evaluation including computerised transaxial tomography and vertebrobasilar angiography should be performed in every case.

Aged↗
PubMed1977

The effect of oral glycerol on intraventricular pressure in man.

Oral glycerol was administered to eight patients with meningeal carcinomatosis or acute leukemia in whom ventricular catheters and Ommaya reservoirs had been implanted for the purpose of intrathecal chemotherapy or chemoprophylaxis. Intraventricular pressure was monitored continuously via the Ommaya reservoirs before and after single doses of 0.5, 1.0 or l.5 gm per kilogram of body weight. The interrelationship between initial pressure, change in pressure, serum osmolarity, and duration of action was investigated, and the ratio of CSF-to-plasma osmolarity was determined 4 to 5 hours after glycerol administration. The effects of chronic 6-hourly and 4-hourly 1 gm per kilogram glycerol doses were studied in a patient with meningeal carcinomatosis and increased intracranial pressure. Our data suggest that as a cerebral dehydrating agent oral glycerol is most effective in patients with markedly increased intracranial pressure. A single 1 gm per kilogram dose is adequate to lower raised intraventricular pressure acutely, but its effect is short-lived. Continuous oral administration must be carefully monitored to avoid the establishment or a reverse osmotic gradient, secondarily increased intracranial pressure, and clinical deterioration.

Administration, Oral↗
PubMed1975

The partial purification and properties of pig brain glycogen synthase.

Both the I (independent of glucose 6-phosphate) and D (dependent on glucose 6-phosphate) forms of glycogen synthase (UDP-glucose:glycogen alpha-4-glucosyltransferase EG 2.4.1.11) have been partially purified from pig brain and the kinetic constants of the enzymes have been examined. The Km for UDP-glucose for the I form increased from 0.11 to 0.5 mM when the temperature was raised from 25 to 37 degrees. When glucose 6-phosphate was present, the Km for UDP-glucose was decreased to 0.03 and 0.08 mM at 25 and 37 degrees, respectively. The amount of glucose 6-phosphate required to produce half-maximal stimulation decreased with increasing UDP-glucose concentration at both temperatures but increased with increasing temperature. The Km for glucose 6-phosphate at 0.03 and 0.20 mM UDP-glucose was 0.13 and 0.10 mM, respectively, at 25 degrees. At 37 degrees and 0.125 and 4.0 mM UDP-glucose the Km for glucose 6-phosphate was 0.32 and 0.04 mM, respectively. The Km for UDP-glucose for the D form at 0.75, 2.0, and 10 mM glucose 6-phosphate was 0.71, 0.50, and 0.42 mM at 25 degrees. At higher temperatures the apparent affinity for the substrate was decreased; at 37 degrees, the Km for UDP-glucose at 0.75 and 2.0 nM glucose 6-phosphate was 5.75 and 1.42 mM, respectively. The requirement for glucose 6-phosphate was decreased when UDP-glucose concentrations were increased; at 0.5 and 5.0 mM UDP-glucose concentrations, the Km for glucose 6-phosphate was 22.7 and 1.82 mM at 25 degrees. As was the case with the I form, the apparent Km for glucose 6-phosphate increased at higher temperatures. At 37 degrees, the Km for glucose 6-phosphate at 0.5 and 5.0 mM UDP-glucose was 43.5 and 6.15 mM. The temperature coefficient for the maximum velocity was 10.1% per degree for synthase I and 8.5% per degree for synthase D between 25 and 37 degrees. The D form of synthase was calculated to be virtually inactive under normal physiological conditions with the substrate concentrations found in the brain. The enzymatic activity calculated for synthase I correlates well with the observed rate of incorporation of UDP-[U-14C]glucose into brain glycogen.

Animals↗
PubMed1968

Amino acid uptake in the developing chick embryo heart. The effect of insulin on glycine and leucine accumulation.

1. The accumulation of [1-(14)C]glycine and the uptake, accumulation, incorporation (into protein, lipid, glycogen) and oxidation of l-[1-(14)C]leucine in 5-day-old chick embryo hearts were investigated in vitro, and the effects of insulin, puromycin and 4-methyl-2-oxopentanoic acid on these processes were studied. 2. With glycine, the ratio of concentration of the labelled amino acid in the cell water to that in medium markedly exceeded unity. Insulin significantly increased this ratio. Puromycin did not prevent the insulin effect. 3. With leucine, the concentration ratio of the labelled amino acid between intracellular and extracellular water approached unity in the absence of puromycin and was doubled by its presence. In neither case did insulin substantially alter this ratio. The addition of 4-methyl-2-oxopentanoic acid had no effect in the absence of insulin, but produced a significant increase of the concentration ratio in the presence of the hormone. 4. Leucine uptake was increased slightly by insulin in all experimental conditions except in the presence of puromycin, where a more pronounced stimulation was observed. The hormone had no effect on the incorporation of the labelled amino acid into protein, but accelerated its oxidation to carbon dioxide; the latter effect was particularly evident in the presence of puromycin and disappeared after the addition of 4-methyl-2-oxopentanoic acid.

Animals↗
PubMedDate not supplied

Graphical analysis of MR feature space for measurement of CSF, gray-matter, and white-matter volumes.

The problem of volume averaging in quantitating CSF, gray-matter, and white-matter fractions in the brain is solved using a three-compartment model and a simple graphical analysis of a multispectral MR feature space. Compartmentalization is achieved without the ambiguities of thresholding techniques or the need to assume that the underlying pixel probability distributions have a particular form. A 2D feature space is formed by double SE (proton density- and T2-weighted) MR data with image nonuniformity removed by a novel technique in which the brain itself serves as a uniformity reference. Compartments other than the basic three were rejected by the tailoring of limits in feature space. Phantom scans substantiate this approach, and the importance of the careful selection and standardization of pure tissue reference signals is demonstrated. Compartmental profiles from standardized subvolumes of three normal brains, based on a 3D (Talairach) coordinate system, demonstrate slice-by-slice detail; longitudinal studies confirm reproducibility. Compartmentalization may be described graphically and algebraically, complementing data displays in feature space and images of compartmentalized brain scans. These studies anticipate the application of our compartmentalization technique to patients with neurological disorders.

Adult↗
PubMedDate not supplied

Quantitative comparisons of image registration techniques based on high-resolution MRI of the brain.

OBJECTIVE: A variety of methods for matching intrasubject MRI-MRI, PET-PET, or MRI-PET image pairs have been proposed. Based on the rigid body transformations needed to align pairs of high-resolution MRI scans and/or simulated PET scans (derived from these MRI scans), we obtained general comparisons of four intrasubject image registration techniques: Talairach coordinates, head and hat, equivalent internal points, and ratio image uniformity. In addition, we obtained a comparison of stereotaxic Z frames with a customized head mold for MRI-MRI image pairs. MATERIALS AND METHODS AND RESULTS: Each technique was quantitatively evaluated using the mean and maximum voxel registration errors for matched voxel pairs within the brain volumes being registered. CONCLUSION: We conclude that fiducial markers such as stereotaxic Z frames that are not rigidly fixed to a patient's skull are inaccurate compared with other registration techniques, Talairach coordinate transformations provide surprisingly good registration, and minimizing the variance of MRI-MRI, PET-PET, or MRI-PET ratio images provides significantly better registration than all other techniques tested. Registration optimization based on measurement of the similarity of spatial distributions of voxel values is superior to techniques that do not use such information.

Algorithms↗
PubMedDate not supplied

The effects of CT drift on xenon/CT measurement of regional cerebral blood flow.

A systematic increase in computed tomography (CT) number of approximately 0.13 Hounsfield unit per scan (HU/scan) was observed when serial DeltaScan 2020 CT scans of a uniform water phantom were equally spaced at 0.5, 1.0, or 2.0 min and a shaped aluminum beam-hardening filter was employed. Much smaller drifts (less than 0.06 HU/scan) were observed with flat aluminum or shaped beryllium oxide filters. This machine drift, which was not associated with a rise in water phantom temperature and did not consistently correlate with estimated x-ray tube heat, could result in a significant overestimation of regional cerebral blood flow (rCBF) for a xenon/CT rCBF protocol involving 5-7 sequential scans obtained at 1-min interscan intervals.

Brain↗