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J Kalef-Ezra

Publications and source records attributed to J Kalef-Ezra.

34 records · Page 2Linked to original sources
PubMed1990

Installation and testing of an optimized epithermal neutron beam at the Brookhaven Medical Research Reactor (BMRR).

NCT is a binary system, in which 10B is physiologically targeted to tumor and then allowed to interact with thermal neutrons generated in the treatment volume by an externally applied neutron beam. Consequently, an unusually large number of parameters are obtained, which bear on the resultant Therapeutic Gain (TG). However, a perusal of these data, as illustrated in Figure 7, indicates that the TG would increase significantly beyond values projected in this paper if the absolute amount of 10B could be increased above 30 ppm. For example, increasing 10B concentration in tumor to 45 ppm would increase TG by approximately 33% (with a T/N of 5). A similar increase in TG would follow an increase in T/N from 5 to 10. Those associated with the development of boron compounds for NCT feel that such developments are within reach.

Boron Compounds↗
PubMed1987

Samarium-145: a new brachytherapy source.

A new radiation source has been produced for brachytherapy, with radiation energies slightly above those of 125I, and a T1/2 of 340 d. This source, 145Sm, is produced by neutron irradiation of 144Sm (96.5% enriched). Decay is by electron capture with 140 K x-rays per 100 disintegrations in the energy region between 38-45 keV, plus 13 gamma-rays at 61 keV. These sources are encapsulated in Ti tubes, approximately 0.8 mm X 4.5 mm, and have been developed for temporary implantation in brain and ocular tumours. The 38-61 keV photons should make such sources easy to shield, while providing a dose distribution from source arrays somewhat more homogeneous than that from 125I. In addition, the 340 d half life of 145Sm permits its use for times significantly longer than that of 60 d 125I. While the 145Sm sources have been designed primarily for implantation in a brain tumour, they should be useful for almost any conventional brachytherapy application.

Brachytherapy↗
PubMedDate not supplied

Effects of delayed (24 h postintervention) beta-irradiation therapy after coronary angioplasty and stenting in de novo native coronary artery lesions; Results of a randomized clinical and intravascular ultrasound study.

BACKGROUND: The effects of brachytherapy performed 24 h postintervention in de novo native coronary artery lesions. METHODS AND RESULTS: Thirty-nine patients with 39 de novo coronary artery lesions were randomised to prompt (immediately after intervention, n=21) or delayed (24 h later, n=18) beta brachytherapy ((90)Sr/(90)Y) after been successfully revascularized with stenting. Clinical follow-up data up to 21 months (median time) were compared. After irradiation and at 6-month follow-up, paired volumetric analysis of the stented segment and the 5-mm proximal and distal reference segments was performed; this included measurements of the external elastic membrane, lumen, plaque, and media (external elastic membrane minus lumen), stent and intima hyperplasia (stent minus lumen). Baseline clinical and angiographic characteristics were similar in the two groups. Postintervention measurements of stent, lumen, and intima hyperplasia volumes as well as postintervention minimum lumen cross-sectional areas were not different. In the stented segments and in the segments 5 mm proximal and distal to the stent, similar changes of all IVUS measurements were measured in the two patient groups, but in the lumen volume at the proximal stent edge of patients irradiated 24 h postinjury. At 21 months median follow-up time, target lesion revascularization (TLR) was performed in 8 patients (38%) in the prompt irradiation group compared with 3 (17%) in the delayed (P=.17). CONCLUSION: Beta irradiation is similarly effective whether performed immediately after percutaneous coronary intervention or 24 h later.

Aged↗
PubMedDate not supplied

External beam irradiation following balloon angioplasty in an atherosclerotic rabbit model.

PURPOSE: To study the effect of external beam irradiation on the morphometry of both angioplasted and nonangioplasted arteries in a hypercholesterolemic rabbit model. METHODS AND MATERIALS: Four groups of rabbit femoral arteries were studied: arteries (a) with no intervention, (b) irradiated with a 12-Gy x-ray dose, (c) treated with balloon angioplasty, and (d) dosed with 12 Gy 30 min after balloon angioplasty. RESULTS: External irradiation did not change vessel morphometry in nonangioplasted arteries. On the contrary, it induced neointimal formation and decreased luminal area, without causing any vessel remodeling in arteries treated with balloon angioplasty. CONCLUSION: External irradiation at 12 Gy given 30 min after angioplasty in the studied model accentuated the neointimal response to vascular injury, without causing any vessel remodeling.

Angioplasty, Balloon↗
PubMedDate not supplied

External beam irradiation in angioplasted arteries of hypercholesterolemic rabbits. The dose and time effect.

PURPOSE: To study the dose and time effect of external beam irradiation on the morphometry of both angioplasted and nonangioplasted arteries in a hypercholesterolemic rabbit model. METHODS AND MATERIALS: Eight groups of rabbit femoral arteries were studied: arteries (a) with no intervention, (b) irradiated with a 12-Gy 6 MV X-ray dose, (c) with a 18-Gy, (d) treated with balloon angioplasty, (e) dosed with 12-Gy half an hour post-angioplasty, (f) dosed with 18-Gy half an hour post-angioplasty, (g) dosed with 12-Gy 48 h post angioplasty, (g) dosed with 18-Gy 48 h post angioplasty. RESULTS: External irradiation at either 12 or 18 Gy was not found to change vessel morphometry in noninjured arteries. The 12-Gy dose given soon after angioplasty further increased percentage stenosis (63% on the average), despite the preservation of the lumen cross-sectional area. Positive remodeling was not observed in arteries given 18-Gy half an hour post angioplasty to counterbalance the increased neointimal formation. Therefore, this treatment resulted in a drastic reduction in lumen area and in enhancement of percentage stenosis (84% on the average). On the contrary, the delayed irradiation of the angioplasted arteries at either 12 or 18 Gy was not found to influence any of the studied morphometric parameters 5 weeks after angioplasty. CONCLUSIONS: Uniform external beam irradiation up to 18 Gy was well tolerated by intact femoral arteries. Prompt 12- or 18-Gy irradiations accentuated percentage stenosis. However the lumen cross-sectional area was preserved only at the lower dose point. Delayed irradiation at any dose did not influence the restenosis process.

Angioplasty, Balloon↗
PubMedDate not supplied

Could X-ray microbeams inhibit angioplasty-induced restenosis in the rat carotid artery?

BACKGROUND: Parallel, thin (<100 microm) planes of synchrotron-generated X rays, have been shown to spare normal tissues and preferentially damage tumors in animal models. The aim of the present study was to assess the effect of such microbeams directed unidirectionally on angioplasted rat carotid arteries. METHODS AND MATERIALS: Three groups of Sprague-Dawley rats were studied: (a) rats with normal, untreated arteries, (b) rats treated by balloon angioplasty, but not irradiated, and (c) rats treated with balloon angioplasty and exposed to single fraction, unidirectional, parallel, microbeams an hour after angioplasty. The microbeam array, 15 mm widex7.6 mm high, consisting of 27-microm-wide beam slices, spaced 200 microm center-to-center laterally traversed the damaged artery. The in-depth in-beam dose was 150 Gy, the "valley" dose (dose midway between microbeams resulting mainly from X-ray scattering) was 4.5 Gy on average, and the "integrated" (averaged) dose was 26 Gy. RESULTS: Microbeam irradiation, as given in the present study, was tolerated, but was insufficient to significantly suppress the neointimal hyperplasia. DISCUSSION: The microbeam dose used is considered low. Dose escalation would be necessary to reach conclusive results regarding the X-ray microbeam efficacy to control restenosis.

Angioplasty, Balloon↗
PubMedDate not supplied

Comparison of measured parameters from a 24-keV and a broad spectrum epithermal neutron beam for neutron capture therapy: an identification of consequential parameters.

Epithermal neutron beams are under development in a number of locations in the U.S. and abroad. The increased penetration in tissue provided by these neurons should circumvent problems associated with the rapid attenuation of thermal neutron beams encountered in previous clinical trials of neutron capture therapy (NCT). Physical and radiobiological experiments with two "intermediate energy" or "epithermal" beams have been reported. A comparison is made here between the 24-keV iron-filtered beam at Harwell, England, and the broad-spectrum Al2 O3 moderated beam at the Brookhaven Medical Research Reactor (BMRR). In addition, parameters which are relevant for NCT, and which are best suited for evaluation and comparison of beams, are discussed. Particular attention is paid to the mean neutron energy which can be tolerated without significant reduction of therapeutic gain (TG), where TG is the ratio of tumor dose to maximum normal tissue dose. It is suggested that the simplest and most meaningful parameters for comparison of beam intensity and purity are the epithermal neutron fluence rate, and the fast neutron dose per epithermal neutron (4.2 X 10(-11) rad/neutron for the broad-spectrum beam and 29 X 10(-11) rad/neutron for the 24-keV beam). While the Al2O3 beam is close to optimal, the 24-keV beam produces a significant fast neutron dose which results in a lower TG.(ABSTRACT TRUNCATED AT 250 WORDS)

Biophysical Phenomena↗
PubMedDate not supplied

Serum tumor markers in non-Hodgkin's lymphomas and chronic lymphocytic leukemia.

The levels of soluble interleukin-2 receptors (sIL-2R), beta-2 microglobulin (beta-2M), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were measured in the serum of 50 previously untreated patients with non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukemia (CLL) as well as in 25 age and sex-matched normal controls. Compared to normal controls, mean serum levels of sIL-2R and beta-2M were significantly increased in both NHL and CLL (p < 0.001) while the increase in ESR and CRP was less marked (p < 0.01 and p < 0.05, respectively). Comparison of these tumor markers with histologic grading showed statistically significant differences only for CRP between low, intermediate and high-grade lymphomas (p < 0.001 and p < 0.05). More advanced stages exhibited higher mean values of all serum markers than early stages (p < 0.001 for sIL-2R, beta-2M and ESR and p < 0.05 for CRP). An association with the presence of b-symptoms was observed only for sIL-2R (p < 0.05). In addition, sIL-2R as well as beta-2M were able to predict time to progression in patients with diffuse large-cell lymphomas. We conclude that of the four tumor markers tested sIL-2R and beta-2M more frequently showed increased serum levels and were associated with clinical stage and/or presence of b-symptoms. Both sIL-2R and beta-2M were also found to have prognostic significance for survival.

Adolescent↗
PubMedDate not supplied

Serum soluble interleukin-2 receptors in epithelial ovarian cancer patients.

The levels of soluble interleukin-2 receptors (sIL-R2) were measured in the serum of 52 patients with epithelial ovarian carcinoma as well as in 25 age and sex-matched normal controls. The mean serum level of sIL-R2 was increased in 37 patients (71.2%). Comparison of these levels to those of normal controls showed a highly statistically significant difference (p < 0.001). Serum sIL-R2 levels were not related to histology, clinical stage or the presence of ascites (p = 0.58, p = 0.32 and p = 0.67, respectively), nor did they follow disease activity or response to chemotherapy. However, patients with higher pretreatment sIL-2R levels (more than 1200 U/ml) were found to have a longer survival (p < 0.02), possibly explained by the presence of activated lymphocytes and a better immune surveillance. We conclude that the serum level of sIL-R2: a) is elevated in ovarian cancer patients, b) has no relationship with histological subtypes, tumor burden or the presence of ascites, c) cannot serve as a valuable tumor marker for the monitoring of patient treatment, and d) has a prognostic value for survival.

Adult↗
PubMedDate not supplied

Soluble interleukin-2 receptors in patients with advanced colorectal carcinoma.

The levels of soluble interleukin-2 receptors (sIL-2R) were measured in the serum of 52 patients with advanced colorectal carcinoma and compared to CEA and CA 19-9 levels. Twenty-five normal, age and sex-matched individuals served as controls. Seventy-five per cent of the patients had increased mean serum levels of sIL-2R (1539 +/- 155 U/ml), while normal controls had mean levels of 555 +/- 31 U/ml (p < 0.001). The relationship with hepatic or lymph nodal metastases showed no statistically significant difference (p = 0.34 and p = 0.47, respectively). Serum sIL-2R levels showed a linear correlation with CEA (p < 0.05). Patients with lower pretreatment sIL-2R levels (less than 1.200 U/ml) had a longer survival than patients with higher initial levels (more than 1.200 U/ml) (p = 0.0049). In conclusion, the present work shows that the serum levels of sIL-2R: a) are elevated in patients with advanced colorectal cancer, b) have no relationship with the type of metastases, c) correlate with serum CEA and d) have a prognostic value for survival.

Adult↗