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Biomedical subjects

C Borel

Publications and source records attributed to C Borel.

At least 37 records · Page 2Linked to original sources
PubMed1999

Residues critical for duck hepatitis B virus neutralization are involved in host cell interaction.

To date, no detailed analysis of the neutralization properties of duck hepatitis B virus (DHBV) has been reported, and it is not clear whether any of the known neutralization epitopes correspond to the viral receptor binding site or to sequences involved in the cell entry pathway. We demonstrate here that antibodies directed against two overlapping peptides (amino acids 83 to 97 and 93 to 107), covering the sequences of most DHBV pre-S neutralizing epitopes, both inhibit virus binding to primary duck hepatocytes and neutralize virus infectivity. An extensive mutagenesis of the motif 88WTP90, which is the shortest sequence of the epitope recognized by the virus-neutralizing monoclonal antibody (MAb) 900 was performed in order to define the amino acids involved in these interactions. Single point mutations within this epitope affected neither virus replication nor infectivity but abolished virus neutralization by MAb 900 completely. Interestingly, mutants with two and three consecutive residue replacements (SIP and SIH) within this epitope retained replication competence but were no longer infectious. The loss of infectivity of SIH and SIP mutant particles was associated with significantly reduced binding to primary duck hepatocytes and could be rescued by trans complementation with wild-type pre-S protein. Taken together, these results indicate that each amino acid of the DHBV pre-S sequence 88WTP90 is critical for recognition by the neutralizing MAb 900 and that replacement of the first two or all three residues strongly reduces virus interaction with hepatocytes and abrogates infectivity. These data imply that the motif 88WTP90 contains key residues which are critical for interaction with both the neutralizing MAb and the host cell.

Animals↗
PubMed1998

Phosphorylation of DHBV pre-S: identification of the major site of phosphorylation and effects of mutations on the virus life cycle.

Four potential serine/threonine phosphorylation sites [(S/T)-P motif], designated P1-P4, on the pre-S protein of duck hepatitis B virus (DHBV) have been mutated. Mutants include single (P2, P3, P4) and double amino acid substitutions (P1 + P2, P3 + P4) and one with all four sites mutated (4P). Serine at position 118 (P3) was identified as the major site of phosphorylation by Western blotting and radioimmunoprecipitation after in vitro cell labeling with [35S]methionine or [33P]orthophosphate. Mutant virions generated by transfection of LMH cells were infectious both in vitro in duck hepatocyte primary cultures and in vivo in Pekin ducks. Intracellular relaxed circular (RC) and covalently closed circular (ccc) DNA syntheses were not affected by the P3 mutation or even the quadruple mutant. Extracellular virus production was slightly increased when the P3 site was mutated. CsCl gradient centrifugation showed no clear difference between mutant and wild-type virus with respect to the ratios of enveloped virus and nucleocapsid particles in hepatocyte culture supernatants. Trypsin or V8 protease digestion with or without NP-40 indicated that phosphorylation of the pre-S domain is not involved in determining the transmembrane topology of DHBV large protein. This phenotypic analysis indicates that DHBV pre-S phosphorylation has no apparent effect on DHBV replication and formation of mature viral particles in duck hepatocyte primary culture and does not affect infectivity in ducklings.

Amino Acid Sequence↗
PubMed1998

Expression studies of the zeaxanthin epoxidase gene in nicotiana plumbaginifolia

Abscisic acid (ABA) is a plant hormone involved in the control of a wide range of physiological processes, including adaptation to environmental stress and seed development. In higher plants ABA is a breakdown product of xanthophyll carotenoids (C40) via the C15 intermediate xanthoxin. The ABA2 gene of Nicotiana plumbaginifolia encodes zeaxanthin epoxidase, which catalyzes the conversion of zeaxanthin to violaxanthin. In this study we analyzed steady-state levels of ABA2 mRNA in N. plumbaginifolia. The ABA2 mRNA accumulated in all plant organs, but transcript levels were found to be higher in aerial parts (stems and leaves) than in roots and seeds. In leaves ABA2 mRNA accumulation displayed a day/night cycle; however, the ABA2 protein level remained constant. In roots no diurnal fluctuation in mRNA levels was observed. In seeds the ABA2 mRNA level peaked around the middle of development, when ABA content has been shown to increase in many species. In conditions of drought stress, ABA levels increased in both leaves and roots. A concomitant accumulation of ABA2 mRNA was observed in roots but not in leaves. These results are discussed in relation to the role of zeaxanthin epoxidase both in the xanthophyll cycle and in the synthesis of ABA precursors.

Journal Article↗
PubMed1998

Inhibitory effect of 2'-fluoro-5-methyl-beta-L-arabinofuranosyl-uracil on duck hepatitis B virus replication.

The antiviral activity of 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil (L-FMAU), a novel L-nucleoside analog of thymidine known to be an inhibitor of hepatitis B virus (HBV) replication in hepatoma cells (2.2.1.5 cell line), was evaluated in the duck HBV (DHBV) model. Short-term oral administration (5 days) of L-FMAU (40 mg/kg of body weight/day) to experimentally infected ducklings induced a significant decrease in the level of viremia. This antiviral effect was sustained in animals when therapy was prolonged for 8 days. The histological study showed no evidence of liver toxicity in the L-FMAU-treated group. By contrast, microvesicular steatosis was found in the livers of dideoxycytidine-treated animals. L-FMAU administration in primary duck hepatocyte cultures infected with DHBV induced a dose-dependent inhibition of both virion release in culture supernatants and intracellular viral DNA synthesis, without clearance of viral covalently closed circular DNA. By using a cell-free system for the expression of an enzymatically active DHBV reverse transcriptase, it was shown that L-FMAU triphosphate exhibits an inhibitory effect on the incorporation of dAMP in the viral DNA primer. Thus, our data demonstrate that L-FMAU inhibits DHBV replication in vitro and in vivo. Long-term administration of L-FMAU for the eradication of viral infection in animal models of HBV infection should be evaluated.

Administration, Oral↗
PubMed1998

Phase II trial of oxaliplatin as first-line chemotherapy in metastatic colorectal cancer patients. Digestive Group of French Federation of Cancer Centers.

PURPOSE: To evaluate the objective tumor response rate and safety profile of oxaliplatin when administered to patients with previously untreated metastatic colorectal adenocarcinoma. PATIENTS AND METHODS: A total of 39 patients were entered onto this phase II trial. One patient was excluded for having had a second cancer, so the study was based on 38 patients. Patients were treated with oxaliplatin 130 mg/m2 as a 2-hour infusion on day 1, every 21 days. Patients were assessed for response every three courses. All clinical and radiologic data were reviewed by an external panel of experts, with their assessment being considered definitive. RESULTS: Nine partial responses (PRs) were observed (response rate, 24.3%; 95% confidence interval, 11.8% to 41.2%). The median duration of response was 216+ days. Fifteen patients (40.5%) had stable disease and 13 (35.2%) had progressive disease. The median progression-free survival time for all patients was 126+ days (range, 21 to 447+). The main toxicity was peripheral sensory neuropathy. Grade 3 neurotoxicity (National Cancer Institute common toxicity criteria [NCI-CTC]) was reported in 13%. Hematologic and gastrointestinal toxicities were mild. The incidence of grade 3 neutropenia was 5.2%, while that of grade 3 or 4 thrombopenia was 7.9%. Vomiting (grade 3 or 4) occurred in 7.9% of patients and grade 3 diarrhea in 2.6%. CONCLUSION: This phase II study provides clear evidence of the safety and efficacy of oxaliplatin monotherapy at this dose and schedule in patients with previously untreated metastatic colorectal carcinoma.

Adenocarcinoma↗
PubMed1998

Design, synthesis and structure relationships of new N,N',N",N"'-tetrakis (omega-amino alkyl) tetraazamacrocycles.

A number of N,N',N",N"'-tetrakis (omega-aminoalkyl) tetraazamacrocycles and related compounds were synthesized and evaluated for their inhibitory effects on human immunodeficiency virus type 1 (HIV-1) and duck hepatitis B virus (DHBV) replication. The activity of these compounds was found to be highly dependent upon structural features: (i) the length of the alkyl linker connecting the nitrogen atoms of the macrocyclic ring to the exocyclic nitrogen atoms of the terminal amino groups (five methylenes favoured antiviral activity); (ii) substitution of the terminal amino groups of the linker reduced antiviral activity; and (iii) the size of the tetraazamacrocyclic ring (14 or 15 atoms) did not markedly affect the antiviral activity. Some analogues were potent inhibitors of HIV-1 replication, with anti-HIV activity similar to that of biscyclam (JM 2763). In contrast, other analogues were found to be highly toxic in duck hepatocyte primary culture, the 2.2.15 cell line and to a lesser extent in MT-4 cells. Structural parameters, macrocyclic ring size and metal-chelating ability have been used to develop a structure-activity relationship model in order to aid the design of antiviral molecules derived from N,N',N",N"'-tetrakis (omega-aminoalkyl) tetraazamacrocycles.

Animals↗
PubMed1997

Breast cancer in patients treated for Hodgkin's disease: clinical and pathological analysis of 76 cases in 63 patients.

In a retrospective multicentric analysis, 63 women treated between 1941 to 1988 for Hodgkin's disease (HD) subsequently developed 76 breast cancers (BC). The median age at diagnosis of HD was 26 years (range 7-67), and 22 women (35%) were 20 years old or less. Exclusive radiotherapy (RT) was used in 36 women (57%) and combined modalities with chemotherapy (CT) in 25 (39%). Breast cancer occurred after a median interval of 16 years (range 2-40) and the median age at diagnosis of the first BC was 42 years (range 25-73). TNM classification (UICC, 1978) showed 10 T0 (non-palpable lesions) (13%), 20 T1 (26%), 22 T2 (29%), 8 T3 (11%), 7 T4 (9%) and 9 Tx (12%), giving altogether a total of 76 tumours, including, respectively, 5 and 8 bilateral synchronous and metachronous lesions. Among the 68 tumours initially discovered, 53 ductal infiltrating, one lobular infiltrating and two medullary carcinomas were found. Moreover, two fibrosarcomas and 10 ductal carcinoma in situ (DCIS) were also found. Among 50 axillary dissections for invasive carcinomas, histological involvement was found in 31 cases (62%). 45 tumours were treated by mastectomy, without (n = 35) or with (n = 10) RT. 27 tumours had lumpectomy, without (n = 7) or with RT (n = 20). 2 others received RT only, and one only CT. 7 patients (11%) developed isolated local recurrence. 20 patients (32%) developed metastases and all died; 38 are in complete remission, whereas 5 died of intercurrent disease. The 5-year disease-specific survival rate by the Kaplan-Meier method was 61%. The 5-year disease-specific survival rate for pN0, pN1-3 and pN > or = 3 groups were 91%, 66% and 0%, respectively (P < 0.0001) and 100%, 88%, 64% and 23% for the T0, T1, T2 and T3T4 groups, respectively. These secondary BCs seem to be of two types: a large number of aggressive tumours with a very unfavourable prognosis (especially in the case of pN > 3 and/or T3T4); and many tumours with a 'slow development' such as DCIS and microinvasive lesions, especially in patients treated exclusively by RT. Moreover, a very unusual rate of bilateral tumours (21%) was observed. These secondary BC could be 'in field', in 'border of field' or 'out of field'. However, a complete analysis of doses delivered by supradiaphragmatic irradiation was often very difficult, due to large variations in several parameters. We conclude that young women and girls treated for HD should be carefully monitored by clinical examination, mammography and ultrasonography.

Adult↗
PubMed1997

Higher doses of alpha-interferon do not increase the activity of the weekly cisplatin-interferon combination in advanced malignant mesothelioma.

Management of advanced malignant mesothelioma (MM) still requires innovative systemic therapy as its prognosis is poorly affected by currently available chemotherapy. The combination cisplatin and alpha-interferon (alpha-INF) has synergistic antitumoral activity in preclinical models and interesting activity in phase I-II clinical trials. Weekly CDDP (60 mg/m2) and alpha-IFN (3 MUI/d: d1-d4) in combination was tested in a previous phase I-II study in 23 MM patients, with a 36% objective response rate (ORR). A trial with higher doses of alpha-IFN in the same combination schedule was conducted to explore an incrementalist hypothesis. Thirty patients with MM received the same CDDP dose (60 mg/m2/w) and doubled doses of alpha-IFN (6 MUI/d: d1-d4). The treatment protocol consisted of two cycles of 4 weeks on/4 weeks off followed by two shorter cycles of 3 weeks on/3 weeks off, in the absence of life-threatening toxicity or progressive disease. All patients were evaluable for toxicity. The main treatment-limiting side-effects were digestive intolerance (nausea, vomiting) and severe asthenia. Antitumoral efficacy was not increased (ORR = 27%). Haematological and neurological toxicities were moderate and manageable. The antitumoral activity of the CDDP-alpha-IFN combination with higher doses of the latter is similar to our previous experience, but tolerance issues make it a poorer choice for eventual comparative trials, or as a standard therapeutic indication.

Adult↗
PubMed1997

[Bilateral breast cancer after Hodgkin disease. Clinical and pathological characteristics and therapeutic possibilities: an analysis of 13 cases].

PURPOSE: Though Hodgkin's disease (HD) is one of the malignancies in which considerable progress has been made, long-term side effects have been observed, second primary cancer being the most significant. Several recent reports have indicated an increased risk of breast cancer (BC) in girls and young women among HD patients. MATERIALS AND METHODS: In a retrospective multicenter analysis, 63 women treated for HD subsequently developed BC. Results that were obtained in 13 women (21%) who developed either synchronous (five cases) or metachronous (eight cases) BC were analyzed. The median age at diagnosis of HD was 19 years. Seven patients underwent exclusive radiotherapy (RT) (including "mantle" supradiaphragmatic irradiation) and six received concomittant radiation therapy and chemotherapy. RESULTS: The first breast tumor occurred after a median delay of 16 years. According to the TNM classification, we showed nine stage T0 (non palpable lesions), four stage T1, five stage T2, one stage T3, two stage T4 and five stage Tx BC. Seventeen infiltrating carcinomas, two fibrosarcomas and seven ductal carcinomas in situ were observed. Among 15 axillary dissections performed for invasive carcinomas, histological involvement was found in 10 cases. Seventeen tumors were treated by mastectomy and nine patients underwent conservative surgical treatment. With a 70-month median follow-up (range: 15-125), three patients developed locoregional recurrence and four other metastases. At present, eight are alive with no evidence of disease and one died of intercurrent disease. CONCLUSION: According to previous works, BC represents 6.3 to 9% of all second cancers occurring after HD treatment. The risk is higher in young women treated before 20 years of age, especially before 15 years of age. Factors that favour the development of secondary BC are: supradiaphragmatic irradiation, very young age at treatment, chemotherapy with alkylating agents, and probably genetic factors. We conclude that young women and girls treated for HD should be carefully monitored at least 10 years after the end of the treatment for HD, using clinical examination, mammography and ultrasonography. The optimal rythm of this follow-up is not yet clearly defined. Moreover, after multidisciplinary concertation, we suggest that secondary BC be sometimes treated by conservative radiosurgical approach.

Adolescent↗
PubMed1997

A phase II study of cisplatin, 5-fluorouracil, leucovorin, and etoposide in advanced non-small-cell lung cancer.

The aim of this study was to define the efficacy of a combination of cisplatin, 5-fluorouracil (5-FU), leucovorin, and etoposide (VP-16) in locally advanced or metastatic non-small-cell lung cancer (NSCLC). From September 1991 to November 1994, 28 patients were treated with cisplatin, 100 mg/m2 i.v. on day 1; 5-FU and leucovorin, 500 mg/m2 on days 1, 2, 3, and 4 by i.v. continuous infusion; and VP-16, 70 mg/m2 i.v. on days 1, 2, 3, and 4 (combination, PFL-VP-16). Cycles were repeated every 3 weeks. There were 22 men and six women. The median age was 58 (range, 41-76). All had measurable diseases (one was stage IIIA, six were IIIB, and 21 were IV). None had previously received chemotherapy for metastatic disease. There was one complete response and six partial responses, for an overall response rate of 25% (95% confidence interval 9-41%). The median response duration and the overall survival were 8 and 9 months, respectively. Limiting toxicity was myelosuppression and oral mucositis. Grade 3 or 4 leucopenia was observed in 20% of all of the 95 cycles administered, and oral mucositis in 13%. No grade 3 or 4 renal toxicity occurred, and neurologic toxicities were limited (3% of the 28 patients experienced grade 3). PFL-VP-16 is active and can easily be administered to patients with advanced NSCLC. However, according to the results obtained with this schedule, VP-16 does not increase either response rate or survival compared with the regimen previously described by Vokes et al. (PFL).

Adult↗
PubMed1997

Selective inhibition of the duck hepatitis B virus by a new class of tetraazamacrocycles.

The antiviral activity of a new class of N,N,N',N",NA'''-pentakis (omega-aminoalkyl) tetraazamacrocycles was evaluated in primary duck hepatocyte cultures infected with the duck hepatitis B virus (DHBV). Three of the four tested compounds were able to selectively inhibit DHBV replication by acting at an early step of the hepadnavirus infection but were associated with significant toxicity.

Antiviral Agents↗
PubMed1996

Complete remission seven years after treatment for metastatic malignant melanoma.

BACKGROUND: In this study, the authors identified seven-year survivors after completion of the French multicenter Phase II trial of fotemustine for the treatment of metastatic malignant melanoma. METHODS: One hundred sixty-nine patients with metastatic malignant melanoma were included in this Phase II study. One hundred fifty-three patient records were evaluable with an overall response rate of 24.2%. RESULTS: Five of these patients are alive and in complete remission. One patient had a complete response after fotemustine administration and then relapsed. One patient had a partial response. Three patients had stable disease. These five patients underwent surgery for relapse or residual disease and subsequently achieved durable complete remission. CONCLUSIONS: Long term survival may be the outcome after surgical resection of residual metastatic melanoma after chemotherapy.

Antineoplastic Agents↗
PubMed1996

2',3'-dideoxy-beta-L-5-fluorocytidine inhibits duck hepatitis B virus reverse transcription and suppresses viral DNA synthesis in hepatocytes, both in vitro and in vivo.

beta-L-Nucleoside analogs represent a new class of potent antiviral agents with low cytotoxicity which provide new hope in the therapy of chronic hepatitis B virus (HBV) infections. We evaluated the anti-HBV activity of 2',3'-dideoxy-beta-L-5-fluorocytidine (beta-L-F-ddC), a beta-L-nucleoside analog derived from 2',3'-dideoxycytidine (ddC), in the duck HBV (DHBV) model. This compound was previously shown to inhibit HBV DNA synthesis in a stably transfected hepatoma cell line (F2215). Using a cell-free system for the expression of an enzymatically active DHBV polymerase, we could demonstrate that the triphosphate form of beta-L-F-ddC does inhibit hepadnavirus reverse transcription. In primary duck hepatocyte culture, beta-L-F-ddC showed a potent inhibitory effect on DHBV DNA synthesis which was concentration dependent. Although beta-L-F-ddC was shown to be less active than ddC against the DHBV reverse transcriptase in vitro, beta-L-F-ddC was a stronger inhibitor in hepatocytes. The oral administration of beta-L-F-ddC in experimentally infected ducklings showed that beta-L-F-ddC is a potent inhibitor of viral replication in vivo. Short-term therapy could not prevent a rebound of viral replication after the drug was withdrawn. Preventive therapy with beta-L-F-ddC could delay the onset of viremia by only 1 day compared with the time to the onset of viremia in the control group. The in vivo inhibitory effect of beta-L-F-ddC was much stronger than that of ddC and was not associated with signs of toxicity. Our data show that beta-L-F-ddC inhibits hepadnavirus reverse transcription and is a strong inhibitor of viral replication both in vitro and in vivo.

Animals↗
PubMed1996

n-Butyrate, a cell cycle blocker, inhibits early amplification of duck hepatitis B virus covalently closed circular DNA after in vitro infection of duck hepatocytes.

During chronic hepadnavirus infection, virus persistence depends on the regulation of the pool of covalently closed circular DNA (cccDNA), which is the template for transcription of viral RNA species. The development of in vitro infection of duck hepatocyte primary cultures by duck hepatitis B virus (DHBV) provides a unique opportunity to study the regulation of cccDNA synthesis. After DHBV in vitro infection, cccDNA is detected 1 day later and is amplified to a high copy number after 1 week in culture. We studied whether this amplification occurs during cell cycle progression of duckling hepatocytes. By using [3H]thymidine incorporation, we found that hepatocytes obtained from 3-week-old ducklings spontaneously entered the S phase of the cell cycle when cultured in serum-free medium without added growth factors. Bromodeoxyuridine labeling confirmed that cellular DNA synthesis took place in more than 50% of parenchymal cells. Cytofluorometry analysis revealed the presence of asynchronous populations and polyploidization processes. The addition of a cell cycle blocker, n-butyrate, completely inhibited [3H]thymidine incorporation and blocked duckling hepatocytes in the G1 phase of the cell cycle. Simultaneously, butyrate inhibited cccDNA amplification and allowed the establishment of DHBV infection, as demonstrated by the detection of a basal level of cccDNA in treated hepatocytes. Both effects were reversible since active cell DNA synthesis was restored and cccDNA accumulated after drug withdrawal.

Animals↗
PubMed1996

Intensive concomitant chemoradiotherapy in locally advanced unresectable squamous cell carcinoma of the head and neck: a phase II study of radiotherapy with cisplatin and 7-week continuous infusional fluorouracil.

PURPOSE: To evaluate an intensive concomitant chemoradiotherapy protocol of conventional radiotherapy with intermittent cisplatin (CDDP) and continuous-infusion fluorouracil (5-FU) in unresectable, locally advanced squamous cell carcinoma of the head and neck (SCCHN). PATIENTS AND METHODS: Fifty-seven patients with unresectable stage IV MO disease (International Union Against Cancer [UICC]/American Joint Committee on Cancer [AJCC], 1987) received radiotherapy 70 Gy followed by CDDP 80 mg/m2 and 5-FU 300 mg/m2/d. Response was assessed 2 months after treatment completion. RESULTS: Thirty patients (52%) received the full treatment schedule; 53 (93%) received full-dose radiotherapy, while 48 (84%) were given at least 75% of the planned chemotherapy doses. Severe mucositis (World Health Organization [WHO]) grade 3 to 4 was the limiting toxicity and was seen in 79% of patients. The median time for mucositis resolution was 8 weeks. Other toxicities were generally manageable, but there were four treatment related deaths (7%). Fifty patients were assessable for activity, with an overall response rate of 70% (95% confidence interval [CI], 58% to 82%). Complete response (CR) and partial response (PR) rates were 42% and 28%, respectively. CONCLUSION: This simultaneous combined-modality regimen was feasible at the cost of severe mucosal toxicity, which required hospitalization with nutritional, parenteral, and hydroelectrolytic support. The high response rate achieved (70%) did not translate into improved survival, probably due to patient eligibility. The likelihood of cure of this high-tumoral-volume patient population remains low (approximately 10%), despite the association of two therapeutic modalities at full standard therapeutic intensity.

Adult↗