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R Gur

Publications and source records attributed to R Gur.

13 recordsLinked to original sources
PubMed1998

Effect of very high single dose of cisplatinum and of radiation on the brain of the rabbit.

The importance of chemotherapy and radiotherapy for treating brain tumors, is well established. In a previous study, a rabbit's brain was treated with doses of up to 12 mg kg-1 of cisplatinum and 4000 cGy, without any morphological or pathological changes. The purpose of this study is to establish the effect of very high single doses of cisplatinum and radiation on the rabbit's brain, applied in 12, 16 and 18 mg kg-1, and 5000, 7500 and 8000 cGy, respectively. The general clinical and neurological condition of the rabbits was unaffected, but areas of alopecia and scalp ulcers appeared. Although these are very high doses of chemotherapy and radiotherapy, the histopathological and morphological examination of the rabbit's brain remained normal.

Animals↗
PubMed1997

Symptomatic patients after craniectomy.

Various surgical procedures in neurosurgery end with cranial vault defects. It is generally believed that the reason for repair of the skull defect is cosmetic or protective. There is evidence, however, that in selected cases neurologic deterioration can be reversed by cranioplasty. In the sinking scalp flap syndrome the deterioration has been thought to be related to the concavity of the skin flap and underlying brain tissue secondary to atmospheric pressure and also to the in-and-out displacement of the brain through the skull defect. Five cases of symptomatic patients after craniectomy are reported, of which all had a neurologic deterioration that was improved by cranioplasty.

Adult↗
PubMed1997

Effect of high simple dose of cisplatinum and of radiation on the brain of rabbit.

In former studies of intracarotid and intravenous administration of cisplatinum, separate and combined with brain irradiation, we found no cerebral damage. In this study, gradually increasing high doses (above the therapeutic ones) of cisplatinum were administered intravenously to one series of rabbits and increasing high amounts of irradiation (above the therapeutic amounts) were given to another series. Although the rabbits that received highest doses of irradiation developed areas of alopecia and skin ulcers on the head, the general clinical and histopathologic examination of the rabbits' brains in both series was normal. The purpose of this study was to establish the effects of high doses of intravenous cisplatinum and irradiation on the rabbits brains.

Alopecia↗
PubMed1996

Age associated decrements in dopamine D2 receptors in thalamus and in temporal insula of human subjects.

This study evaluates the effects of age on DA D2 receptors in extrastriatal regions. DA D2 receptor availability was evaluated in 42 healthy male subjects (mean age 41 +/- 16, range 21 - 86 year old) with positron emission tomography (PET) and [11C]raclopride. Estimates of Bmax/Kd were obtained using the ratio of the distribution volume in the region of interest (caudate, putamen, thalamus, frontal, occipital cortices, temporal insula, cingulate and orbitofrontal gyri) to that in cerebellum. Correlations between age and D2 receptors were significant in putamen (r = -0.58, p < or = 0.0001), caudate (r = -0.54, p < or = 0.0002), thalamus (r = -0.33, p < or = 0.03) and temporal insula (r = -0.39, p < or = 0.01) but not in any of the frontal regions. The decrease in DA D2 receptor availability was 6.6% per decade in caudate, 8.2% in putamen, 7.6% in thalamus and 13% in temporal insula. This study indicates that D2 losses with age are not limited to striatum and involve also thalamic as well as temporal cortical regions.

Adult↗
PubMed1996

Effect of the combination of cisplatinum and radiation in the rabbit's brain.

The effect of cisplatinum as a potential radiosensitizer in brain tumors is controversial. We examined the effect of the combination of cisplatinum with radiation compared to radiation alone in rabbits' brain. All rabbits were irradiated and cisplatinum was injected intravenously into part of them. Therapeutic doses of cisplatinum and irradiation were given. The rabbits were euthanised at different intervals according to protocol. The general clinical and neurological condition of the rabbits was unaffected, and histopathological examination of the rabbit's brain was normal. The purpose of this study was to establish the effect of cisplatinum followed by cranial irradiation in therapeutic doses to the normal rabbit's brain.

Animals↗
PubMed1996

Dopamine transporters decrease with age.

UNLABELLED: Postmortem studies have documented degeneration of dopamine cells with age, but the changes that occur in healthy aging individuals is less clear. The purpose of this study was to evaluate the extent to which age-induced changes in dopamine transporters occur in subjects with no evidence of motor impairment. METHODS: We evaluated 23 right-handed healthy volunteers (age range 20-74 yr) using PET and [11C]d-threo-methylphenidate. The ratio of the distribution volume for [11C]d-threo-methylphenidate in striatum to that in cerebellum was used as model parameter for dopamine transporter availability (Bmax/Kd + 1). RESULTS: Dopamine transporter availability was significantly lower in subjects > 40 yr of age than in those < 40 yr. Estimates of dopamine transporter availability showed a significant negative correlation with age both for the putamen (r = -0.72, p < 0.0001) and the caudate (r = -0.74, p < 0.0001). Dopamine transporter availability was higher in the left than in the right putamen but did not differ between the left and right caudate. CONCLUSION: This study documents a 6.6% decrease per decade of life in striatal dopamine transporters of healthy volunteers.

Adult↗
PubMed1985

Superficial temporal-middle cerebral artery anastomosis: effects on vascular, neurologic, and neuropsychological functions.

In 44 patients, we studied the effects of superficial temporal-middle cerebral artery anastomosis on cerebral blood flow (CBF), neurologic examination, and cognitive functions. At 3 months, there was significant improvement in all variables. At 9 months, CBF was no longer significantly greater, but neurologic examination and cognitive functions had further improved. Patients with TIA had significant postoperative decreases in TIA frequency and did not progress to stroke, but had no significant changes in any variable. In stroke patients, we could not separate the effects of surgery from the natural evolution of changes in CBF and examination after stroke. None of the preoperative measurements predicted postoperative clinical improvement.

Adult↗
PubMed1983

Positron emission tomographic studies of sensory stimuli, cognitive processes and anxiety.

Research in detecting regional changes in brain metabolism related to functional activity is reviewed and supplemented by original results from positron emission tomography (PET) and the 18F-fluorodeoxyglucose method (FDG). A formula for calculating the value of local cerebral glucose metabolism (LCMRGlc) is discussed. Results concerning auditory stimulation suggest that metabolic responses are determined by the stimulus content and analysis strategy used by the subject rather than the side of stimulation. Tactile stimulation of the hand and fingers caused asymmetrical increases in LCMRGlc confirming topographic maps of the postcentral gyrus and other functional studies. Data from visually stimulated normal subjects show how the visual hemifields project to the opposite calcarine cortex. Studies of patients with hemianopsia or various field defects demonstrated that metabolic scanning can reveal alterations of cortical function not detectable by CT scan. Data obtained reveal the ability of metabolic mapping to subdivide the occipital cortex into distinct regions. Such measurements may also anticipate the course of visual recovery. Findings of increased overall right-hemispheric metabolism during the performance of verbal and spatial cognitive tasks are consistent with earlier results from right-handed males. Results for the frontal eye fields provide the first experimental evidence that lateralized metabolic activity, produced by cognitive tasks, causes similarly lateralized activity within a motor region. It is further demonstrated that FDG is able to provide information on such states as vigilance and anxiety.

Anxiety↗
PubMedDate not supplied

Clinical determinants of long-term survival in patients with glioblastoma multiforme.

Repeated reports of more than ten years postoperative survival in patients with glioblastoma multiforme (GM) have appeared in the literature over the last decades. Authors have tried to identify the clinical, therapeutic and histological features determining long-term survival. We present two patients in whom, after radical removal of the tumor followed by conventional radiation, there has been no recurrence for at least ten years. The young age of the patients and the radical surgical approach were in accordance with previous reports of long-term survival. Nevertheless, one tumor originated from the thalamus, a location considered to be of unfavorable prognosis. We therefore further discuss the value of clinical signs as determinants in the prognosis of GM.

Adolescent↗
PubMedDate not supplied

Meningiomas after radiotherapy for tinea capitis--still no history.

AIMS AND BACKGROUND: To review the clinical, radiological and histological findings of 19 patients with radiation-induced intracranial meningiomas treated at our neurosurgical department between 1981 and 1996. METHOD: The records of 18 patients with intracranial meningiomas who underwent low-dose radiation for tinea capitis in childhood, and of one patient irradiated for pituitary adenoma, were analyzed in respect of the previously reported features of postradiation meningiomas. RESULTS: The mean age of the patients with low-dose radiation-induced meningiomas was 58 years and the mean shortest onset latency was 48 years. The male to female ratio was 1.1:1. Forty-seven percent of patients presented with mental changes and/or focal neurological signs, 21% with signs of increased intracranial pressure and 26% with seizures. Calvarial location of the meningiomas was found in 54% of patients and in one patient the tumor arose from the skull base. Multiple tumors were present in 15% of patients and 29% of the meningiomas displayed malignant features on histological examination. A significantly lower meningioma recurrence rate was found in our series compared to the recurrence rate in the reported series of postradiation meningiomas. Five patients had a history of a second neoplasm other than meningioma. CONCLUSION: Our series of low-dose radiation-induced meningiomas represents one of the largest of its kind in the English literature. The patients did not differ substantially in sex ratio, tumor localization, multiplicity and histological features from the previously reported postradiation meningioma patients, except for the significantly lower tumor recurrence rate. It would seem that over the next years we will be further witnessing the deleterious effects of low-dose radiation administered in childhood.

Adult↗