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G Prevot

Publications and source records attributed to G Prevot.

At least 19 recordsLinked to original sources
PubMed1998

Combined use of FLUKA and MCNP-4A for the Monte Carlo simulation of the dosimetry of 10B neutron capture enhancement of fast neutron irradiations.

Boron neutron capture enhancement (BNCE) of the fast neutron irradiations use thermal neutrons produced in depth of the tissues to generate neutron capture reactions on 10B within tumor cells. The dose enhancement is correlated to the 10B concentration and to thermal neutron flux measured in the depth of the tissues, and in this paper we demonstrate the feasibility of Monte Carlo simulation to study the dosimetry of BNCE. The charged particle FLUKA code has been used to calculate the primary neutron yield from the beryllium target, while MCNP-4A has been used for the transport of these neutrons in the geometry of the Biomedical Cyclotron of Nice. The fast neutron spectrum and dose deposition, the thermal flux and thermal neutron spectrum in depth of a Plexiglas phantom has been calculated. The thermal neutron flux has been compared with experimental results determined with calibrated thermoluminescent dosimeters (TLD-600 and TLD-700, respectively, doped with 6Li or 7Li). The theoretical results were in good agreement with the experimental results: the thermal neutron flux was calculated at 10.3 X 10(6) n/cm2 s1 and measured at 9.42 X 10(6) n/cm2 s1 at 4 cm depth of the phantom and with a 10 cm X 10 cm irradiation field. For fast neutron dose deposition the calculated and experimental curves have the same slope but different shape: only the experimental curve shows a maximum at 2.27 cm depth corresponding to the build-up. The difference is due to the Monte Carlo simulation which does not follow the secondary particles. Finally, a dose enhancement of, respectively, 4.6% and 10.4% are found for 10 cm X 10 cm or 20 cm X 20 cm fields, provided that 100 micrograms/g of 10B is loaded in the tissues. It is anticipated that this calculation method may be used to improve BNCE of fast neutron irradiations through collimation modifications.

Biophysical Phenomena↗
PubMed1998

Selective delivery of 10B to soft tissue sarcoma using 10B-L-borophenylalanine for boron neutron capture therapy.

Boron neutron capture therapy (BNCT) may improve the locoregional control of radio/chemoresistant tumours like soft tissues sarcomas (STS). This technique uses the 10B(n,alpha)7Li nuclear reaction to destroy tumour cells, provided that a sufficient amount of 10B may be carried selectively into them. In order to evaluate the targeting potential of 10B-L-borophenylalanine (BPA) a 10B biodistribution study was carried out in 24 Wistar rats bearing Yoshida sarcoma. Six animals received increasing intraperitoneal doses of BPA (300, 600 and 1200 mg kg-1), while the remainder received a BPA dose of 600 mg kg-1 but with a sacrifice at six different time points: 1, 2, 4, 6, 9 and 12 h. The 10B concentrations in the tumours, normal tissues and blood were analysed with neutron capture radiography (NCR). The analysis shows that 36 micrograms g-1 (+/- 4 SD) of 10B may be incorporated into the tumour, with a ratio of 13 (+/- 4 SD) versus the muscle and a ratio of 15 (+/- 3 SD) versus the blood, 6 h after an intraperitoneal injection of 600 mg kg-1 of BPA. The BPA appears to be abundantly incorporated in the tumour, and the kidney proximal tubule area. These data suggest that BNCT using BPA may provide an improved therapeutic ratio for the treatment of STS.

Animals↗
PubMed1993

[Cancer of the breast in men. 106 cases].

In a retrospective and multicentre study 106 cases treated from 1970 to 1985 were analysed. The patients' median age was 64 years. TNM classification showed 20 T1, 48 T2, 2 T3, 32 T4 and 4 Tx. Twenty one patients had clinical gynaecomastia; 99 underwent surgery and 85 radiotherapy; 32 received adjuvant chemotherapy or hormonal therapy. The main histological type was ductal infiltrating carcinoma; 82 axillary dissections were performed, and positive lymph nodes were found in 67 percent of the cases. Hormone receptors were positive in 15 out of 20 measured cases. Five and 10 years overall survival rates (Kaplan-Meier) were 57 and 37 percent, and corrected survival rates 68 and 55 percent respectively. The main prognostic factor remains the clinical size of the tumour (T) and histologically axillary node status (pN). Eleven patients developed a second metachronous cancer. The aetiology of male breast cancer is a poorly known as that of female breast cancer. Nevertheless, imbalance among oestrogens and androgens due to metabolic, infectious or pharmacological causes is probably responsible, at least in part, for this cancer. An on-going multicentre prospective national trial tries to address this question.

Adult↗
PubMed1988

Combination of recombinant interferon alpha-2a and vinblastine in advanced renal cell cancer.

Among 40 evaluable patients with metastatic renal cell cancer treated by high-dose interferon alpha-2a in combination with vinblastine, the authors have observed a 42.5% response rate. The 8 months' median duration of remissions is relatively short but some patients experience very long remissions, lasting many months after discontinuation of therapy. The survival of responding patients is significantly longer than the survival of nonresponders. The diverging results of other studies of the same combination are discussed; its efficacy is certainly dependent on the type of interferon, on the dose actually administered, and on the compliance to this often poorly tolerated treatment.

Adult↗
PubMed1987

[Treatment of metastatic renal adenocarcinomas with combined recombinant alpha-2a interferon and vinblastine].

The results of treatment of metastatic renal cell carcinoma have so far been very poor. Many phase II studies have shown that interferon alpha therapy is active in a significant proportion of patients (approximately 10 to 15% complete and partial remission). In the hope of improving these results we have conducted a phase I-II study of the combination of interferon alpha-2a and vinblastine in 21 patients with metastatic renal cell cancer. Side-effects were pronounced and the mean tolerated doses were 12.5 x 10(6) U/m2 interferon alpha three times per week and 0.10 mg/kg vinblastine once every three weeks. We observed a 43% response rate, with 1 complete remission, 8 partial remissions, 4 stabilizations and 8 progressions. These very encouraging results need to be confirmed by large scale studies.

Adenocarcinoma↗
PubMed1987

[Negative contrast in x-ray computed tomography. Preliminary study].

For the abdominal and pelvic CT Scan, the authors propose the filling of the bladder, the duodenal loop, the stomach and the rectum with a lipidic emulsion. The negative density of this emulsion allows a better visualization of the pancreas, the gastric wall and the bladder wall as well as the extension of pelvic and bowel tumors.

Contrast Media↗
PubMed1985

Mitoxantrone combined to vincristine, cyclophosphamide and fluorouracil in advanced breast cancer.

In our wide experience of treating advanced breast carcinoma with chemotherapy, the combination of doxorubicin (DOX), vincristine (VCR), cyclophosphamide (CPM) and fluorouracil (FU) gave a complete plus partial response rate of over 60%, with 100% alopecia and frequent cardiac toxicity depending on total dose. After the EORTC Clinical Screening Group phase II trial we have conducted an "expected difference method" comparative phase II trial using the combination DOX, VCR, CPM, FU and the combination of MTX (10mg/m2), VCR, CPM and FU on a population of 50 breast carcinoma patients similar to those taking part in the first study. The reasons for similarity of action will be presented and discussed.

Adult↗
PubMedDate not supplied

[Concurrent split-course chemotherapy and radiotherapy for unresectable stage III non-small cell lung cancer: preliminary results of a Phase II study].

PURPOSE: We initiated at Hospital de Mulhouse a prospective phase II study to assess a split-course concurrent radiochemotherapy in locally advanced non-small cell lung cancer. MATERIALS AND METHODS: From March 1996 to December 1997, 28 patients were included in our study. All patients had a stage III cancer. The chemotherapy scheduled included vinorelbine (20 mg/m2/d, d1 and d5), cisplatin (20 mg/m2/d, from d1 to d5), and 5-Fluorouracil (350 mg/m2/d, from d1 to d5 by continuous infusion). The planned irradiation dose was 12.5 Gy per week with one daily fraction of 2.5 Gy from d1 to d5. Cycles were repeated every four weeks, for four cycles (50 Gy). Patients with a partial or complete response were proposed a fifth cycle. RESULTS: Of the 28 patients of the study, only 27 were analysed; one patient had a metastatic disease at diagnosis. Major hematologic toxicity occurred in 26% of the patients. One to five cycles of chemoradiotherapy were administrated per patient (median: four). Four patients had received fewer than three cycles and their responses were not assessable. Of the 23 patients assessed, 12 responses (52%) were observed, three CR (13%) and nine PR (39%). Median follow-up was 14 months, and median survival 13.5 months. One- and two-year survival rates were respectively 63% and 14%. Local control rates was 11%, and 44% of the patients had a metastatic evolution. CONCLUSION: Very preliminary results of this phase II study are disappointing, and quite inferior to the published results using chemoradiotherapy with conventional or hyperfractionated radiotherapy. Hematologic toxicity is restrictive. This type of chemoradiotherapy cannot be recommended.

Adult↗
PubMedDate not supplied

[The life cycle of Maritrema misenensis (A. Palombi, 1940), n. comb. (Trematoda: Microphallidae, Travassos, 1920) from French Mediterranean coast (author's transl)].

The life cycle of Maritrema misenensis (A. Palombi, 1940) n. comb. is described with illustrations. The sporocysts parasite the digestive gland of the Prosobranch snail Cerithium mediterraneum. The cercariae are the same as Cercaria misenensis, A. Palombi, 1940 described from Italian coast. The adults have been obtained by artificial infestations of Larus argentatus michaellis. Their morphological features are same as those of the caribbean species Maritrema patulus W.H. Coil, 1955. When the life cycle of the American species is pointed out, it will be possible to know whether there are two or only one species.

Animals↗
PubMedDate not supplied

[Life-cycle of Renicola lari J. Timon-David, 1933 (Trematoda, Renicolidae) (author's transl)].

This paper deals with life-cycle of Renicola lari J. Timon-David, 1933. Description and illustration are given. Sporocyst development occurs inside the visceral mass of Cerithium mediterraneum and C. Rupestre (Mollusca Prosobranchia). Cercariae are planktonic; they are swallowed up by the second intermediate host, Atherina hepsetus and A. boyeri (Teleostean fishes). Cercariae perforate intestine wall. Metacercariae are encysted in liver. Adult flukes have been recovered in kidneys of uninfected Larus argentatus and L. ridibundus after exerimental contamination with naturally infected fishes. Cercariae of Renicola lari differ from Plagiorchid type cercariae by the following characters : stylet lacking ; very large excretory bladder ; they develop into metacercariae in fishes. Cercariae of R. lari seem to Rhodometope type cercariae ; they have the same excretory bladder. Cercariae of R. lari differ from Rhodometope cercariae in lacking fins on their tail.

Animals↗
PubMedDate not supplied

[Demonstration of the existence of a marine cycle in the strigeides: Cardiocephalus longicollis Szidat, 1928 (Trematoda: Strigeidae)].

During their investigations on parasitism of fishes and birds in the lagoon of Brusc (Var), the authors have discovered the life cycle of Cardiocephalus longicollis. Cercariae of pharyngeate furcocercous type develop in sporocysts in the digestive gland of the marine prosobranch Nassa corniculum. The cercaria is identified as Cercaria nassae (Dolgikh, 1965) from Nassa reticulata in Black sea; it closely resembles Cercaria nassa (Martin, 1945) from Ilyanassa obsolseta (syn. Nassa obsoleta) at Woods Hole (U.S.A.). Several intermediate hosts have been related; they are the marine fishes Diplodus annularis, D. vulgaris, Boops salpa, Pagellus mormyrus (Sparidae) and Belone belone (Scombresocidae). Metacercariae of tetracotyle type were found in the cavity of optical lobes of the brain. Experimental contamination of fishes: Potamoschistus microps, Blennius sp., Mugil cephalus and Syngnathus abaster has been negative; that of Diplodus annularis and D. sargus, positive. It allowed to follow the development from cercaria to tetracotyle. In Provence natural definitive hosts are Larus argentatus and L. ribidundus; contaminations of these birds with metacercariae experimentally raised in Diplodus annularis and D. vulgaris were successfull. Some observations are pointed out especially the development of the parasite in the definitive host, the organisation of tribocytic organ and the geographical distribution of the parasite.

Animals↗