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A Verbist

Publications and source records attributed to A Verbist.

16 recordsLinked to original sources
PubMed1997

Tumor type and vascularity: important variables in infusional brachytherapy with colloidal 32P.

PURPOSE: This study investigated the role of histologic tumor characteristics, in comparison with a normal tissue, and of tumor vascularization on the uptake and retention of colloidal 32P used in infusional brachytherapy of solid cancers. The cytotoxicity of colloidal 32P was also evaluated for two tumors of different radiosensitivity, a melanoma, and a squamous cell carcinoma. METHODS AND MATERIALS: An in vitro analysis of colloidal 32P uptake was carried out on a human melanoma cell line, HBL, a human squamous cell carcinoma, SCC1, and normal fibroblasts, F-NBB. Tumor retention of colloidal 32P was studied in vivo for the HBL and the SCC1 tumors implanted subcutaneously in nude mice. Tumor vascular density was determined by microscopic study of Masson's trichrome slides of HBL and SCC1 tumors of about 1 cm diameter. RESULTS: In vitro studies showed that the time required for maximal cell uptake of colloidal 32P was only 10-20 min for the SCC1 and HBL tumors, while it took at least 60 min for the fibroblasts. After intratumoral injection of macroaggregated albumin (MAA), followed by 50 microCi of colloidal 32P, Bremsstrahlung imaging performed at 6 and 24 h showed that the activity remained in the HBL tumor while some of the radiocolloids leaked from the SCC1 tumor and was trapped in the reticuloendothelial system of the liver. Organ activity counting confirmed this finding: 32P activity was three to four times higher in the HBL than in the SCC1 tumor, whereas the activity in the liver, insignificant in the HBL mice (less than 0.1 microCi/g), was as high as 24 microCi/g in the SCC1 mice. This phenomenon may be explained by the difference in tumor vascular density, estimated for the HBL to be about four times less than that of the SCC1 tumor (5.7 vs. 21.4 blood vessels per mm2 for the HBL and the SCC1 tumors, respectively). CONCLUSION: Intratumoral infusion of colloidal 32P may be a useful complement of radiation therapy in the treatment of nonresectable but accessible solid tumors. Tumor vascularization must be taken into account for a successful vascular blockade by MAA prior to the infusion of colloidal 32P.

Animals↗
PubMed1986

Which diphosphonate for routine bone scintigraphy (MDP, HDP or DPD)?

Of 790 patients, 772 with proven cancerous disease have been studied without any selection using either MDP (three different kits), HDP (two types) or DPD. The groups were identical in age distribution, male/female ratio, body weight and verified percentage metastatic involvement. Technical conditions (Mo/Tc-generator used, dilution volume, total activity of the final product per vial, preparation/injection and injection/examination delays) were identical. Analogous scintigrams according to qualitative criteria (image quality, bone delineation, soft tissue fixation, metastatic/normal tissue contrast, aspecific uptake by non-target organs) and superior to MDP. Quantitative data were quite similar for all types of diphosphonates spine; metastatic/normal bone fixation ratio, bone/soft tissue ratio) have been evaluated. The results obtained showed that there was no criterion to demonstrate that HDP or DPD would be superior to MDP. Quantitative data were quite similar for all types of diphosphonates studied. Two out of the three MDPs were slightly superior to the other products with regard to detectability of metastatic lesions. Our results show, that in non-selected clinical routine work for bone scintigraphy HDP and DPD do not present any decisive qualitative or quantitative advantage in comparison to MDP.

Adolescent↗
PubMed1983

Dynamic 131I-labelled insulin distribution in rabbits as seen by in-vivo scintigraphic studies.

The kinetics of 131I-labelled insulin distribution in heart, liver, kidneys and urinary bladder of rabbits were studied in vivo by gamma-camera techniques combined with plasma measurements (glucose concentrations and chromatographic separation of insulin and its degradation products). The distribution space of radioiodinated insulin differed from the vascular bed delineated by radioiodinated serum albumin. During a 20-min gamma-camera recording, radioactive degradation products only appeared in the plasma after 10-12 min. Previous administration of a 10 000-fold excess of unlabelled insulin and 5 ml glucose (20%) did not modify the evolution of 131I-labelled insulin cardiac invasion and the subsequent linear decrease of radioactivity. Conversely, wash-out of radioactivity from the liver and kidney was accelerated after preadministration of this excess of unlabelled hormone, binding in these organs accounting for this acceleration. Urinary bladder filling was imaged later than cardiac, hepatic or renal labelling and was only accelerated by polyuria induced by glucose injection, independent of preadministration of unlabelled hormone.

Animals↗
PubMed1980

Influence of 1% enflurane (Ethrane) anesthesia on regional cerebral blood flow repartition under normo-and hyperventilation.

This study is based on the same group of neurosurgical patients as our previous publication. All, except one, had suffered from head injury. We made a first measurement of rCBF under N2O anesthesia, a second under N2O + 1% enflurane anesthesia, both at a PaCO2 of 40 Torr. A third measurement was performed under N2O + 1% enflurane but at a PaCO2 of 30 Torr. The method we used consists of the intracarotid injection of 133Xe and recording of the radioactivity by a gammacamera. Mean arterial pressure was maintained constant by an intravenous phenylephrine drip. For each measurement of each patient, a map was drawn, representing the distribution of the regional cerebral blood flows (rCBF), compared to the mean value of the hemisphere. We have studied rCBF in one case of normal hemisphere, and in cases of traumtic lesions in acute and chronic states, taking into account that the normal brain exhibits areas with higher flow in the frontoparietal and insular regions. In the normal brain, introduction of 1% enflurane decreases uniformally mean CBF, rCBF repartition not being changed. Hyperventilation to 30 Torr shows that regions with previously higher flow react more to hypocapnia by a slightly more decreased flow. In severe brain trauma, mean CBF is generally low, and it is difficult to visualize the lesions under N2O and N2O + 1% enflurane anesthesia. Neither mean CBF, nor rCBF repartition are significantly modified. On the other hand, in the acute phase, hypocapnia causes a more decreased flow in the previously well irrigated areas, and shows a lack of vascular reactivity in the damaged region. Passing to the chronic state, the patient clinically recovering, the rCBF repartition is normalized and the contused area becomes agains vasoactive. Severe losses of neuronal tissue are characterized by definitive low flows without reactivity by hyperventilation.

Adolescent↗
PubMed1980

Effect of 1% enflurane (Ethrane) anesthesia on cerebral blood flow and metabolism in neurosurgical patients during normo- and hyperventilation.

We have measured the CBF in ten neurosurgical patients. A first measurment was made during anesthesia with nitrous oxide 70% and a second with nitrous oxide 70% + 1% enflurane, both at a PaCO2 of 40 Torr. A third measurement was performed also with nitrous oxide + 1% enflurane, but at a PaCO2 of 30 Torr. We used the method of intracarotid 133Xe injection, with a gammacamera recording. In order to avoid any decrease of cerebral perfusion pressure, which might influence the CBF, an infusion of phenylephrine was used, if needed. At a constant PaCO2 of 40 Torr, there was no statistically significant difference in CBF with nitrous oxide + 1% enflurane compared to nitrous oxide alone. No change in cerebral vascular resistance was observed. When PaCO2 was lowered to 30 Torr, under 70% nitrous oxide + 1% enflurane, there was a 43% decrease in CBF (from a mean of 42 ml/100 G/min. to a mean of 24 ml/100 g/min.). Cerebral vascular resistance had an increase of 79%. In some instances, the decrease in CBF reached values around 20 ml/100 g/min. and in one case, even less. That level is generally considered to be the lowest acceptable limit in the conscious man, though not necessarily in the anesthetised one. Under hypocapnia, the cerebral arterio-venous oxygen difference increased, but the CMRO2 did not change. There were little differences in lactate and pyruvate cerebral metabolic rates, all values remaining within normal ranges. In conclusion, we believe that enflurane is a favorable anesthetic agent for neurosurgical operations at the concentration of 1%, CMRO2 is reduced, there is no significant effect on cerebral blood vessels, CBF and CVR do not change. However, a complementary use of hypocapnia may reduce CBF to dangerously low levels, if at the start, it shows already a pathological decrease and if hyperventilation is applied at a marked degree.

Adolescent↗
PubMed1976

Changes in regional cerebral blood flows produced by dexamethasone in patients with brain metastases.

Four patients suffering from brain metastases were studied by brain scintigraphy carotid angiography and rCBF measurement, before and after one week of treatment with dexamethasone. It was noted that the neurological signs and the blood perfusion around the tumor were improved but that the volume of the lesion, as judged from the angiogram was unmodified. It is suggested that the corticosteroids reduce tissue pressure before actually diminishing the volume of the brain oedema.

Adult↗
PubMed1976

Cerebral blood flow under enflurane anesthesia.

Cerebral blood flow was measured, under controlled conditions of stable ventilation and PaCO2, in 11 patients suffering from cerebro-vascular lesions. Comparing the results under N2O-enflurane 1% anesthesia with those under N2O-fentanyl anesthesia shows an average 8.4% decrease of blood flow. In 5 cases, a third measurement was performed under N2O-enflurane 2% anesthesia. This caused an average 8.5% complementary decrease. Whereas most inhalational anesthetic agents produce an increase of cerebral blood flow, this is not observed with enflurane, the tendency rather being towards a decrease.

Adult↗
PubMed1975

A rapid method for evaluation of regional cerebral blood flow after intra-arterial injection of 133Xe.

A technique based on the stochastic method is described for the computation of regional blood flow (RBF) after intra-arterial infection of 133Xe. Results are presented on scintigrams, defined by 600-800 channels in a 64 times 64 matrix. The content of each channel is equal to the computed RBF value. The standard deviation is also computed for each channel. The total computation cycle is achieved within 10 min. The method has been used to investigate the influence of anesthesia or drugs on regional blood flow. For this purpose, a differential printout program was written in which variations of RBF values between the two measurements are expressed in units of a fixed percentage; provision is made for calculation of RBF variations in units of differential standard deviations. Data are in good accordance with other clinical findings. This method is suitable for clinical use when blood flow values in gray and white substances are not requested.

Adolescent↗
PubMedDate not supplied

Action of vasodilators on regional cerebral blood flow in subacute or chronic cerebral ischemia.

Regional cerebral blood flow (bicompartmental and stochastic method) was measured in a series of 20 patients with unilateral brain softening. Measurements were repeated during the administration of a vasodilator. A deterimental effect on the perfusion of the disease area was observed in the majority of cases. It has been shown that the chances for a vasodilator to decrease the perfusion in the diseased area were greater when the angiogram showed obstruction of an intracranial artery.

Adolescent↗