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P Richaud

Publications and source records attributed to P Richaud.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Conservative treatment of infiltrating cancer of the bladder: neoadjuvant chemotherapy and radiotherapy].

PURPOSE: Retrospective evaluation of tolerance and efficacity of a combination of chemotherapy and radiotherapy in non metastatic invasive cancer of the bladder. MATERIALS AND METHODS: From 1984 to 1995, 36 patients presenting with invasive urothelial carcinoma of the bladder were treated conservatively with primary chemotherapy: cisplatin-methotrexate-vinblastine (24 patients), methotrexate-vinblastine-doxorubicin-cisplatin (11 patients) or carboplatin (one patient). Fourty-six Gy were then delivered by external radiation therapy to the pelvis, with a complement of 10 to 20 Gy to the bladder. Seventeen patients received a concomitant chemotherapy with cisplatin. RESULTS: The intolerance to chemotherapy was hematologic and digestive. One patient died from bone marrow depletion. External irradiation was well tolerated, except for one patient whose treatment was stopped at 48 Gy. Fifteen tumours (44%) were in complete remission (CR) after chemotherapy and 23 (64%) at the end of treatment. With a median follow up of 64.6 months, 13 out of 23 patients in CR had a relapse (ten local relapses, three metastatic); five salvage cystectomies were done. The median survival and 26 months and the probability of survival at 5 years was 43%. All but two patients surviving 5 years had a functional bladder. CONCLUSION: Neoadjuvant chemotherapy leads to CR in 44% of patients and CR is observed in 64% of the patients after radiation therapy. However, the survival rate at 5 years is insufficient, even if the rate of bladder conservation is high.

Aged↗
PubMed1997

A randomized double blind placebo controlled multicenter study of mesalazine for the prevention of acute radiation enteritis.

BACKGROUND AND PURPOSE: Symptoms of acute radiation enteritis (ARE), dominated by diarrhea, occur in more than 70% of patients receiving pelvic irradiation. Eicosanoids and free radicals release have been implicated in the pathogenesis. Mesalazine (5-ASA) is a potent inhibitor of their synthesis in the mucosa and could therefore be of some interest in preventing ARE. PATIENTS AND METHODS: The study was performed in six radiotherapy units in France who agreed on standardized irradiation procedures. One hundred and fifty-three patients planned for external beam radiotherapy to the pelvis > or = 45 Gy for prostate (n = 97) or uterus (n = 54) cancer were randomized on a double blind basis to receive prophylactic 5-ASA (4 g/day Pentasa) or placebo. Patients with concomitant chemotherapy were excluded. Prostate and uterus cancers were chosen since these centropelvic tumors require a similar radiotherapy protocol during the first step of treatment and involve a comparable volume of small intestine. The symptoms of ARE and their severity were assessed every week during irradiation, and 1 and 3 months after its end. All patients followed a low fiber and low lactose diet. End points were diarrhea, use of antidiarrheal agents, abdominal pain, and body weight. Effficacy was evaluated using intention to treat. RESULTS: (means +/- SD) Groups did not differ for age (mean 64 +/- 9 years), sex, tumor site, or irradiation procedure. During irradiation, diarrhea occurred in 69% and 66% of the 5-ASA and placebo groups, respectively (chi2, P = 0.22). Curves of survival without diarrhea did not differ between groups (logrank P = 0.09). Severity of diarrhea did not differ between groups except at d15 where it was significantly more severe in the 5-ASA group (ANOVA P = 0.006). Duration of diarrhea did not differ (22 +/- 15 days in both groups, P = 0.88). Abdominal pain was less frequently reported in the 5-ASA group at d28 (34% vs. 51%, P = 0.048). Use of antidiarrheal agents and body weight did not differ between groups. CONCLUSION: Mesalazine 4 g/day did not decrease the symptoms of ARE.

Acute Disease↗
PubMed1997

[Splenic irradiation in myeloid hemopathies: evaluation and toxicity].

PURPOSE: Splenomegaly occurs frequently in patients with myelofibrosis (MF) or chronic myelogenous leukemia (CML), indicating significant splenic metaplasia. Symptomatic radiation therapy can be delivered, but the best irradiation scheme is still unknown. Results of splenic irradiation in patients with myelofibrosis or chronic leukemia were retrospectively analyzed. PATIENTS AND METHODS: There were 24 patients: 15 presented with MF and 9 with CML. Median irradiation doses were 9.8 and 7.7 Gy, respectively. The hematologic toxicity was moderate (except for platelets in the acute phase of the disease). RESULTS: No toxicity was observed. Various factors predictive of the response to radiation therapy are described. While high (around 14 Gy) radiation therapy dose appears necessary for MF and should be started before the increase in transfusion need, huge splenomegalies should be excluded in regard to CML. As for other cases, the optimal dose is still unclear, but should probably be high enough, ie, around 10 Gy. CONCLUSION: To further study and better understand biological mechanisms underlying response to radiotherapy in patients with MF, prospective radio-chemotherapy phase II trials should be conducted in both CML and MF patients.

Aged↗
PubMed1997

[Mediastinal large B-cell lymphoma. A retrospective anatomic-clinical study of 26 cases].

Mediastinal B-cell lymphomas (with or without sclerosis) have been recently recognized as an entity with particular clinical features. We report 26 patients with a mediastinal large B-cell lymphoma. They represent 5% of the patients with aggressive non-Hodgkin's lymphoma and 2% of all non-Hodgkin's lymphoma seen in our centre between 1962 and 1990. They include 19 females (73%) and 7 males (27%). The sex ratio was 2.7 and the median age was 44 years (range: 17-84 years). Compressive symptoms in relation with a bulky mediastinum were present in 21 cases (80%) and with B symptoms in 5 cases. All these patients received 2 to 4 cycles of chemotherapy with a CHOP-like protocol (epirubicin or doxorubicin, cyclophosphamide, vincristine and prednisone) followed in 24 cases by mediastinum irradiation (40 Gy). Two patients progressed during chemotherapy and did not receive radiotherapy. Nineteen patients had a consolidation chemotherapy according to the same protocol. Twenty-one patients achieved a complete remission after chemotherapy or radiotherapy and 5 failed. Two patients relapsed at 10 months and 9 years. Seventeen patients are alive and in first complete remission with a median follow-up of 102 months (range: 60-260 months). Using the Kaplan-Meier method, the overall survival at 5 and 10 years was respectively 77 and 61% and the relapse-free survival was respectively 68 and 57%. These results confirm the previous findings concerning this distinct entity which is characterized by a predilection for young women, compressive symptoms, a slow response to treatment and a rather good prognosis.

Adolescent↗
PubMed1996

Evidence for a proximal histidine interaction in the structure of cytochromes c in solution: a resonance Raman study.

Soret-excited resonance Raman (RR) spectra of oxidized and reduced cytochromes ć from Rhodospirillum molischianum and Rhodobacter sphaeroides, in solution, are reported. The spectra of the type I ferricytochromes ć in both species contain different extents of two forms. One of these is readily assignable to a "normal" five-coordinated high-spin heme. The second species with v3 and v10 modes at 1502 and 1635 cm-1, respectively, is attributed to a five-coordinated intermediate-spin heme. The RR data show that the equilibrium between these two forms is species-dependent at neutral pH and 20 degrees C. The v(Fe-His) mode of the a form of reduced cytochromes ć is assigned to a band at 228-231 cm-1, indicating that the proximal His has a strong electronegative character. X-ray crystallographic data on R. molischianum ferricyt ć show that the proximal His has no interaction with either the protein or water molecules [Finzel, B.C., Weber, P.C., Hardman, K.D., & Salemme, F.R.(1985) J. Mol. Biol. 186, 627-643]. Considering that the absence of H bonding at the coordinated histidine corresponds to a low frequency for the v(Fe-His) mode (195-205 cm-1), the structure and/or environment of the proximal histidine appears different for cyt ć (III) in the crystal and cyt ć (II) in aqueous solution. To account for the elevated frequency of the v(Fe-His) mode of cyt ć (II), several possibilities have been examined. Among these, we propose that a conserved Lys residue, located in the protein sequence three residues before the His ligand, can form an electrostatic interaction with the (His)N1 atom, directly or through a water molecule. It is further suggested that this electrostatic interaction could also play a role in the high-spin <--> intermediate-spin equilibrium of oxidized cytochromes ć.

Amino Acid Sequence↗
PubMed1996

Characterisation of the mcpA and mcpB genes capable of encoding methyl-accepting type chemoreceptors in Rhodobacter capsulatus.

Two contiguous mcp genes, mcpA and mcpB, transcribed from the same DNA strand and capable of encoding methyl-accepting chemotaxis proteins (Mcp) have been isolated from Rhodobacter capsulatus (Rc), sequences and overexpressed in Escherichia coli (Ec). The deduced proteins (McpA, 69 171 Da; McpB, 81 629 Da) show a structure similar to that of Ec Mcp. The products of mcpA and mcpB, overproduced in Ec, were recognized by anti-Ec Mcp (Trg) antibodies.

Amino Acid Sequence↗
PubMed1996

Recurrences of rectal cancers: results of a multimodal approach with intraoperative radiation therapy. French Group of IORT. Intraoperative Radiation Therapy.

PURPOSE: Prognosis of recurrent rectal cancer remains poor, mainly because of the difficulties of achieving a satisfactory local control. Intraoperative radiation therapy (IORT) allows for the delivery of a complementary single dose to the tumor residues or to the tumor bed and could be useful jn a multimodal treatment. In an attempt to evaluate this interest, a retrospective analysis of patients treated with IORT in six French hospitals has been performed. METHODS AND MATERIALS: Data have been collected in 73 patients (41 men), with a mean age of 62 years, treated with IORT. Initial rectal tumors were large (mean diameter: 45 mm), partially or totally fixed to the contiguous structures in 39%, and with nodal involvement in 50% of the cases. Initial surgery had been a sphincter-sparing surgery in 67%; external radiation therapy had been delivered in 52%, and a chemotherapy had been given in 10% of the patients. Recurrences were isolated (without metastases) in 86%, and were posterior or posterolateral in 55% of the cases. Surgery allowed for a complete macroscopical resection in 57%, a partial resection with gross residual disease in 29%, and no resection in 14% of the recurrences. Intraoperative radiation therapy was delivered in a dose of 10 to 25 Gy (mean 18.5) through localizators of a mean diameter of 75 mm (60 to 110). External radiation therapy, either preoperative or postoperatively was given to 30 patients without prior radiation therapy. Ten patients received additional chemotherapy with 5-fluorouracil. RESULTS: Four postoperative deaths occurred. Postoperative morbidity occurred in 16 patients and some complications were probably related to the IORT procedure. Four long-term complications were observed. Overall actuarial survival occurred in 72.4% of the patients at 1 year, in 44.6% at 2 years, and in 30.6% at 3 years. Twenty-one local failures have been observed. Actuarial local control occurred in 71.3% of the patients at 1 year, 47.7% at 2 years, and 31.3% at 3 years. CONCLUSION: Intraoperative radiation therapy is a complementary treatment for recurrences of rectal cancer. It provides encouraging results, particularly in some selected situations, when patients have not previously been treated with external radiation therapy. Further studies of multimodal treatments are necessary.

Adult↗
PubMed1996

Intraoperative radiation therapy in recurrent carcinoma of the uterine cervix: report of the French intraoperative group on 70 patients.

PURPOSE: To evaluate the feasibility and oncologic results of intraoperative radiation therapy (IORT) for recurrent uterine cervical carcinoma in a cohort of patients treated in seven French institutions. METHODS AND MATERIALS: From 1985 to 1993, 70 patients with pelvic recurrences underwent IORT with/ without external radiation therapy (ERT) and chemotherapy (CT). Treatment modalities for recurrence were IORT alone (40 out of 70), IORT + ERT (30 out of 70), additional chemotherapy (20 out of 70). Gross complete resection (CR) was performed in 30 out of 70 cases, partial resection (PR) in 37 out of 70, and unspecified surgery in 3 out of 70. Sixty-five patients had electron beam IORT and 5, 100 KV photon IORT. Mean IORT cone size, electron beam energy, and dose (calculated at the 90% isodose line) were, respectively, 75 mm (40 to 90), 12 MeV (6 to 20), and 18 Gy (10 to 25) after CR and 80 mm (45 to 100), 15 MeV (7 to 24), and 19 Gy (10 to 30) after PR. RESULTS: Mean follow-up after IORT was 15 months (2 to 69). One, 2- and 3-year overall survival rates were 47, 17, and 8%, respectively; median survival was 11 months and local control, 21%. Median survival and local control rates increased after CR (13 months, 27%) vs. PR (10 months, 17%) and when initial treatment consisted of surgery (S) alone (15 months, 25%) vs. radiation therapy (RT +/- S) (10 months, 16%). However, these differences were not statistically significant. No death-related toxicity was observed. Grade 2 or 3 toxicity was observed in 19 out of 70 patients (27%), including 9 not directly IORT-related complications (13%) (three digestive tract fistulas, one rectal stricture, three urinary fistulas, two infections) and 10 directly IORT-related complications (14%) (five neuropathies, four ureteral obstructions, and one rectal stricture). CONCLUSION: This retrospective study demonstrates the feasibility of IORT. The usefulness of IORT still needs to be evaluated in primary treatment of advanced stages of cervical carcinoma.

Adult↗
PubMed1996

Is there any place for a wait-and-see policy in stage I0 follicular lymphoma? A study of 43 consecutive patients in a single center.

BACKGROUND: A wait-and-see policy (WS) does not appear to modify the long-term prognosis of advanced-stage follicular lymphomas (FL), while irradiation of limited stages sometimes causes complications and does not avert distant relapses. Consequently, we decided to test WS in a selected subset of the localized FL, i.e., patients in complete remission (CR) after the initial lymph node biopsy (stage I0). PATIENTS AND METHODS: Forty-three previously untreated patients were diagnosed with stage I0 FL and 26 of them were included in the WS. Their median age was 60.3 years; 19 were male and 24 female. All histological slides were reviewed and confirmed the diagnosis of FL. Median follow-up was 6.3 years (y). RESULTS: Thirteen of the 26 untreated patients are still relapse-free, while six relapsed locally only (median: 4.2 years after diagnosis), and reattained CR with radiotherapy. Seven patients relapsed at distant sites (median: 1 year after diagnosis). No localized relapses were observed in the treated group, but there were 7 distant relapses. CONCLUSIONS: The use of WS in stage I0 FL did not appear to modify the prognosis of these patients. Furthermore, we observed two distinct patterns of relapse (local and distant) that are difficult to differentiate at onset.

Adult↗
PubMed1996

Sequential 1H and 15N NMR resonance assignment and secondary structure of ferrocytochrome c2 from Rhodobacter sphaeroides.

Sequence-specific 1H and 15N assignments have been made for the amino acids of the ferrocytochrome c2 from Rhodobacter sphaeroides. Initial assignments were made by analysis of a series of homonuclear 2D COSY, TOCSY, and NOESY spectra obtained with the unlabeled protein. 2D and 3D 1H-15N correlated spectra obtained for a uniformly 15N-labeled ferrocytochrome c2 were used to confirm and extend the assignments. Partial 13C assignments have also been made by means of HSQC experiments on 13C at natural abundance, in particular for about two-thirds of the 13C alpha. Medium-range NOE connectivities, together with 3J(HC alpha NH) coupling constants, indicated the presence of five helices at positions 6-16, 60-68, 74-82, 84-91, and 109-120. No other regular secondary structure was observed. This folding is similar to that previously observed for the ferrocytochrome c2 of Rhodobacter capsulatus in solution, which exhibits approximately 50% sequence identity. Moreover, the rotation rates of the aromatic rings of phenylalanine or tyrosine, when conserved, were similar to those observed for R. capsulatus. Furthermore, C alpha H chemical shifts, which are sensitive to the secondary structure and ring current effects of the heme, appear to be very similar for the two proteins. Consequently, the solution structure of R. sphaeroides ferrocytochrome c2 appears to be very similar to that of R. capsulatus ferrocytochrome c2. These results are compared with the X-ray crystal structure of the R. sphaeroides ferrocytochrome c2.

Amino Acid Sequence↗
PubMed1995

In vivo participation of a high potential iron-sulfur protein as electron donor to the photochemical reaction center of Rubrivivax gelatinosus.

We have found that the only high redox potential electron transfer component in the soluble fraction of Rubrivivax gelatinosus TG-9 is a high-potential iron-sulfur protein (HiPIP). We demonstrated the participation of this HiPIP in the photoinduced electron transfer both in vivo and in vitro. First, the addition of HiPIP to purified membranes enhanced the rate of re-reduction of the photooxidized reaction center. Second, the photooxidation of HiPIP was observed in intact cells of Ru. gelatinosus TG-9 under anaerobic conditions by EPR and absorption spectroscopies. Analysis of flash-induced absorption changes showed that the equilibration of positive equivalents between the reaction center and HiPIP occurs in less than 1 ms after flash excitation. The complete re-reduction of the photooxidized reaction center is achieved in tens of milliseconds. The turnover of a cyt bc1 is also involved in this reaction, as shown by a slow electrogenic phase of the membrane potential linked to this process.

Electron Spin Resonance Spectroscopy↗
PubMed1995

Radiotherapy and chemotherapy for invasive thymomas: a multicentric retrospective review of 90 cases. The FNCLCC trialists. Fédération Nationale des Centres de Lutte Contre le Cancer.

PURPOSE: Thymoma is a rare disease. The treatment of patients with invasive thymoma remains controversial. The prognosis of such patients is poor, even with the use of postoperative radiation therapy and chemotherapy. We retrospectively reviewed the outcome and prognostic factors in a series of 90 patients presenting with an invasive thymoma treated by partial resection or biopsy and radiation therapy. METHODS AND MATERIALS: From 1979-1990, 163 patients with the diagnosis of lymphoepithelial thymoma were treated in 10 French cancer centers. Patients were staged using the postoperative "GETT" classification derived from that of Masaoka. Ninety patients who presented with an invasive thymoma, 58 Stage III (21 IIIA: partial resection and 37 IIIB: biopsy) and 32 Stage IVA (intrathoracic thymoma spread), are the subject of this report. Treatment combined surgery and radiation therapy (+/- chemotherapy), with curative intent. Surgery consisted of partial resection in 31 patients (21 Stage III), and biopsy in 55 patients (37 Stage III). The median radiation dose to the tumor was 50 Gy (30-70 Gy). Supraclavicular radiation was performed in 59 patients (median dose 40 Gy). Chemotherapy, combined with radiation in 59 patients, consisted of multidrug regimens, mainly platinum based. RESULTS: The median follow-up is 105 months (20-165 months). The 5- and 10-year overall survival rates are 51 and 39%, respectively. There is a great impact of the extent of surgery on survival: the 5- and 10-year survival rates were 64% and 43%, respectively, after partial resection, compared to 39% and 31% after biopsy (p < 0.02). Local control at 8.5 years was obtained in 59 of 90 patients (66%): 40 Stage III, 19 Stage IVA. There is a significant relationship between the extent of surgery and the local control (16% of relapse after partial resection vs. 45% after biopsy, p < 0.05). Seven patients developed significant (grades 3-4 WHO grading system) treatment-induced side effects. Stage, histologic type, and chemotherapy were not prognostic factors. CONCLUSION: In this large multicentric retrospective study of invasive thymomas (Stage III-IVA) treated by surgery and radiation, results show the importance of loco-regional treatments, such as surgery and radiation therapy. There is also a great impact of radiation on local control. However, the rate of local recurrence (34%) justifies recommending a higher dose of radiation (> 50 Gy) than doses used in this study, for incompletely resected patients. The role of chemotherapy needs to be further assessed.

Adolescent↗
PubMed1995

Phase I-II study of the somatostatin analogue lanreotide in hormone-refractory prostate cancer.

Lanreotide (BIM 32014), a somatulin analogue, was found to be as effective as castration in a rat prostate tumor model. Therapeutic benefit was also demonstrated in the hormone-resistant phase of this tumor model. The activity of lanreotide may be due to a reduction in the levels of growth factors such as insulin growth factor 1 (IGF1). A total of 30 patients with hormone-refractory prostate cancer were treated with a slow-release formulation of lanreotide. The mean age was 71 years. Patients were treated with one intramuscular injection of 30 mg BIM 23014 once a week and were followed for prostate-specific antigen (PSA) level evolution until disease progression or WHO grade 3 or 4 toxicity and for survival. The patients were treated for a mean duration of 12 weeks (range, 2-60 weeks). The performance status and bone pain were improved in 40% and 35% of patients respectively. In all, 20% of the patients had a decrease of > or = 50% in PSA levels and 16% showed a stabilization. The biological response was correlated with clinical improvement. The 1-year global survival rate was 72%, with the rate being 89% in the group of patients who were responders on PSA plasma level and 64% in patients with progressive disease. The response duration ranged from 16 to 60 weeks. Toxicity was minor, with transient grade I digestive side effects being noted in a few patients. Lanreotide given at 30 mg once a week to patients with metastatic hormone-refractory prostate cancer was well tolerated. The response rate was higher than that reported in recent published series. Higher doses of lanreotide should be evaluated.

Aged↗
PubMed1995

Thymoma: results of a multicentric retrospective series of 149 non-metastatic irradiated patients and review of the literature. FNCLCC trialists. Fédération Nationale des Centres de Lutte Contre le Cancer.

Between 1979 and 1990, 149 patients with non-metastatic thymomas were treated in ten French cancer centers. Patients were staged according to the 'GETT' classification, derived from that of Masaoka. There were 13 stage I patients, 46 stage II, 58 stage III and 32 stage IVA. Gross total resections were performed in 63 cases, subtotal resections in 31 cases and in 55 cases a biopsy alone was performed. All patients received radiotherapy and 74 were given post-operative chemotherapy. Median follow-up was 7.7 years. Local control was achieved in 117 cases (78.5%) and was influenced by the stage of the disease (p < 0.01) and the extent of surgery (p < 0.01). Twenty-six patients developed metastatis after a median period of 9 months. Five- and ten-year disease-free survival rates were 59.5% (51-67%) and 49.5% (39-60%), respectively, and were influenced by the stage of the disease (p < 0.01), the extent of surgery (p < 0.001) and a mediastinal compression on presentation (p = 5 x 10(-6)). Four factors could predict a worse overall survival in the multivariate analysis: mediastinal compression on presentation (p < 0.001), absence of chemotherapy (p < 0.001), biopsy alone (p = 0.003), and young age (p = 0.013). A worse DFS was predicted by mediastinal compression on presentation (p < 0.001), absence of chemotherapy (p < 0.001), young age (p = 0.006), and stages III-IVA (p = 0.04). Future therapeutic strategies are discussed and the literature is reviewed.

Adolescent↗
PubMed1995

[Radiotherapy of thymoma. Study of the literature apropos of a retrospective and multicenter series of 149 cases].

Thymomas is a rare disease. Staging systems and surgical adjuvant treatments remain controversial. We retrospectively reviewed the outcome and the prognostic factors in a series of 149 patients with non metastatic thymomas treated in ten French cancer centers between 1979 and 1990. Patients were staged according to the "GETT" classification derived from that of Masaoka. There were 13 stage I patients, 46 stage II, 58 stage III and 32 stage IV. Surgery consisted of complete resection in 63 patients, partial resection in 31 patients and biopsy alone in 55 patients. All patients received postoperative radiation therapy and 74 were given postoperative chemotherapy. Median follow-up was 7.7 years. Local control was obtained in 117 patients (78.5%) and was influenced by the extent of surgery (p < 0.0001). Metastases occurred in 26 patients. Seven patients developed grade 3-4 pulmonary and heart complications. One patient developed a malignant lymphoma after 24 cycles of chemotherapy. Disease-free survival (DFS) rates were of five years 92%, 75%, 60%, 39% and 48% in stage I, II, IIIA, IIIB and IVA patients, respectively. After complete resection, partial resection and biopsy alone, these rates were 74%, 60% and 38%, respectively. With a multivariate analysis, DFS rates were influenced by the extent of surgery (p < 0.001) and by chemotherapy (p < 0.001). Three other factors could predict a worse DFS: young age (p < 0.006), stages III-IV (p < 0.04) and mediastinal symptoms (p < 0.001), "GETT" staging correlated well with local control and survival. After complete resection, a 50 Gy postoperative radiation therapy can be recommended in patients with invasive thymomas. Despite a 65% local control rate after partial resection or biopsy alone in this series, a higher dose of radiation (> 60 Gy) must be evaluated. Despite the benefit of the chemotherapy in this retrospective and multicentric study, the role of this treatment remains to be assessed.

Adolescent↗
PubMed1994

Radiobiological features of acute myeloblastic leukemia: comparison of self-renewal versus terminally differentiated populations.

PURPOSE: To evaluate the radiosensitivity of self-renewing progenitor cells in acute myeloblastic leukemia (AML), we have compared the radiosensitivity of the cells grown either in methylcellulose alone for 7 days, or first in suspension culture for 7 days before being plated in methylcellulose. Methylcellulose selects for terminal-dividing cells and suspension cultures have been developed because they allow self-renewal to occur: The exponential growth of the progenitors of AML cultured in suspension is due to self-renewal. METHODS AND MATERIALS: Cells were harvested from previously untreated leukemic human bone marrows. The myeloblastic lineage of the colonies was assessed by morphological, cytochemical, and immunophenotypic analysis, and by the use of growth factors that did not stimulate the growth of T-lymphocytes. The cell-cycle distribution of the blasts was analyzed by flow cytometry and was comparable for all samples. The irradiation was performed with gamma-photons at a dose-rate of 0.05 Gy/min, similar to the clinical conditions used in our institution for total body irradiation (TBI). RESULTS: The culture methods selected aggressive leukemias. There were large variations of the individual radiosensitivity whatever culture method was used. The progenitor cells capable of self-renewal were more radiosensitive than terminal dividing cells. In two cases, a shoulder was found in the initial part of the cell-survival curves of cells capable of self-renewal. In these two cases, the best fit for the data was the linear quadratic model (survival = e-alpha D-beta D2) with alpha/beta values of 1.49 Gy and 3.12 Gy, respectively. CONCLUSION: The very low values of alpha/beta suggest a reduced antileukemic effect in case of fractionated TBI, and may lead to more reliable screening methods to determine the most appropriate technique for radiation ablation of bone marrow prior to bone marrow transplantation (BMT).

Adolescent↗