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Biomedical subjects

A Ribas

Publications and source records attributed to A Ribas.

At least 37 records · Page 2Linked to original sources
PubMed2000

Genetic immunotherapy for cancer.

Genetic immunization refers to treatment strategies where gene transfer methods are used to generate immune responses against cancer. Our growing knowledge of the mechanisms regulating the initiation and maintenance of cytotoxic immune responses has provided the rationale for the design of several genetic immunization strategies. Tumor cells have been gene-modified to express immune stimulatory genes and are then administered as tumor vaccines, in an attempt to overcome tumor cell ignorance by the immune system. With the description of well-characterized tumor antigens, multiple strategies have been proposed mainly aimed at optimal tumor antigen presentation by antigen-presenting cells (APC). Among APC, the dendritic cells have been recognized as the most powerful cells in this class, and have become the target for introducing tumor antigen genes to initiate antitumor immune responses. The detailed knowledge of how the immune system can be activated to specifically recognize tumor antigens, and the mechanisms involved in the control of this immune response, provide the basis for modern genetic immunization strategies for cancer treatment.

Antigens, Neoplasm↗
PubMed2000

Comparative study of sequential combinations of paclitaxel and methotrexate on a human bladder cancer cell line.

We investigated the cytotoxic effect of different sequential combinations of paclitaxel (Taxol, TX), an antimicrotuble agent, and methotrexate (MTX), a potent inhibitor of dihydrofolate reductase, on a human bladder cancer cell line (T24). The results obtained with a colony-forming assay 5 days after 24 hr of exposure to TX alone showed a strong decline in colony growth up to a concentration of 6 nM. There was a plateau phase at TX concentrations ranging from 6 to 10 nM. The IC50 values found with the different dosing sequences and 24-hr exposure to the drugs were 0.24 microM for MTX alone, 3.49 nM for TX alone, 3.84 nM for TX followed by MTX, 3.75 nM for TX and MTX simultaneously, and 2.10 nM for MTX followed by TX. The cytotoxic effect due to drug interactions in the different sequential combinations was evaluated by an algebraic method. All the combination sequences were found to be synergistic (combination index [CI] < 1) at low TX concentrations. An antagonistic effect (CI > 1) was obtained at higher TX concentrations. Our data demonstrate that the T24 cell line is sensitive to TX and that the cytotoxic effect is enhanced to different degrees depending on the treatment sequence when TX is combined with MTX. These findings could have implications in the design of appropriate administration schedules of these two drugs for the treatment of bladder cancer.

Antimetabolites, Antineoplastic↗
PubMed2000

The shifting patterns of metastatic melanoma.

Management of cutaneous melanoma becomes more difficult as tumor cells metastasize to sites that are remote from the primary tumor. There is a hierarchy of risk associated with cancer spread by different routes and to different organs. Differences in clinical outcome indicate critical variations in pathobiology at different stages in disease evolution. Prevention of the evolution of melanoma is critical, especially beyond the stage of nodal involvement.

Biopsy, Needle↗
PubMed1999

p53 selective and nonselective replication of an E1B-deleted adenovirus in hepatocellular carcinoma.

An E1B gene-attenuated adenovirus (dl1520) has been proposed to have a selective cytolytic activity in cancer cells with a mutation or deletion in the p53 tumor suppressor gene (p53-null), a defect present in almost half of human hepatocellular carcinomas (HCCs). In this study, the in vitro and in vivo antitumor activity of dl1520 was investigated focusing on two human HCC cell lines, a p53-wild type (p53-wt) cell line and a p53-null cell line. dl1520 was tested for in vitro cytopathic effects and viral replication in the human HCC cell lines Hep3B (p53-null) and HepG2 (p53-wt). The in vivo antitumor effects of dl1520 were investigated in tumors grown s.c. in a severe combined immunodeficient mouse model. In addition, the combination of dl1520 infection with systemic chemotherapy was assessed in these tumor xenografts. At low multiplicities of infection, dl1520 had an apparent p53-dependent in vitro viral growth in HCC cell lines. At higher multiplicities of infection, dl1520 viral replication was independent of the p53 status of the target cells. In vivo, dl1520 significantly retarded the growth of the p53-null Hep3B xenografts, an effect augmented by the addition of cisplatin. However, complete tumor regressions were rare, and most tumors eventually grew progressively. dl1520 had no effect on the in vivo growth of the p53-wt HepG2 cells, with or without cisplatin treatment. The E1B-deleted adenoviral vector dl1520 has an apparent p53-dependent effect in HCC cell lines. However, this effect is lost at higher viral doses and only induces partial tumor regressions without tumor cures in a human HCC xenograft model.

Adenoviridae↗
PubMed1999

Alpha-fetoprotein-specific genetic immunotherapy for hepatocellular carcinoma.

The majority of human hepatocellular carcinomas overexpress alpha-fetoprotein (AFP). Two genetic immunization strategies were used to determine whether AFP could serve as a target for T-cell immune responses. Dendritic cells engineered to express AFP produced potent T-cell responses in mice, as evidenced by the generation of AFP-specific CTLs, cytokine-producing T cells, and protective immunity. AFP plasmid-based immunization generated less potent responses. These novel observations demonstrate that this oncofetal antigen can serve as an effective tumor rejection antigen. This provides a rational, gene therapy-based strategy for this disease, which is responsible for the largest number of cancer-related deaths worldwide.

Animals↗
PubMed1999

Generation of human T-cell responses to an HLA-A2.1-restricted peptide epitope derived from alpha-fetoprotein.

Alpha-fetoprotein (AFP) is often derepressed in human hepatocellular carcinoma. Peptide fragments of AFP presented in the context of major histocompatibility molecules could serve as potential recognition targets by CD8 T cells, provided these lymphocytes were not clonally deleted in ontogeny. We therefore wished to determine whether the human T-cell repertoire could recognize AFP-derived peptide epitopes in the context of a common class I allele, HLA-A2.1. Dendritic cells genetically engineered to express AFP were capable of generating AFP-specific T-cell responses in autologous human lymphocyte cultures and in HLA-A2.1/Kb transgenic mice. These T cells recognize a 9-mer peptide derived from the AFP protein hAFP(542-550) (GVALQTMKQ). Identified as a potential A2.1-restricted peptide epitope from a computer analysis of the AFP sequence, hAFP(542-550) proved to have low binding affinity to A2.1, but slow off-kinetics. AFP-specific CTL- and IFN-gamma-producing cells recognize hAFP(542-550)-pulsed targets. Conversely, hAFP(542-550) peptide-generated T cells from both human lymphocyte cultures and A2.1/Kb transgenic mice recognized AFP-transfected targets in both cytotoxicity assays and cytokine release assays. These lines of evidence clearly demonstrate that AFP-reactive clones have not been deleted from the human T-cell repertoire and identify one immunodominant A2.1-restricted epitope. These findings also clearly establish AFP as a potential target for T-cell-based immunotherapy.

Amino Acid Sequence↗
PubMed1999

[The consumption of drugs and natural remedies in the older population of a rural area].

OBJECTIVES: To evaluate the knowledge about medical treatment on people with more than 70 years old, specifically, the understanding, reason for prescription and dosage. To describe the use of natural remedies in the rural environment. To correlate the medication and the natural remedies consumption with health's self-perception. DESIGN: Cross-sectional study. SETTING: Health Center of Santa Eugènia de Berga. Barcelona. PATIENTS: Covered people aged 70 or more, not in an institution, selected by systematic sampling obtained from an updated age and sex register. MEASUREMENTS: A standard questionnaire was used, gathering aspects about medicine and natural remedies consumption and health's self-perception. RESULTS: The average of medicines was 3.08 (SD 2.5) for person. Therapeutics groups most prevalent were cardiovascular and nervous system drugs. The patients remembered correctly the reason of the prescription of the 77% of the medicines and the dosage of the 85%. The 25% of patients needed assistance of some family for to take the medication. We have found statistical significance between health's self-perception and the number of consumed drugs. The 47% of aged population used natural remedies. CONCLUSIONS: The knowledge of medical treatment of our elderly people is satisfactory. We detect in our study a high rate of polymedication. It is necessary, if possible, to rationalize and to reduce the number of drugs. It is useful to revise and to update periodically the elderly people medication. The natural remedies is included on the people's pharmacology and its use is important.

Aged↗
PubMed1998

Generation of melanoma-specific cytotoxic T lymphocytes by dendritic cells transduced with a MART-1 adenovirus.

Dendritic cells (DC) are potent stimulators of primary T cell responses. In this study, we demonstrate that DC, genetically engineered to express the MART-1/Melan-A (MART-1) tumor-associated Ag, express MART-1 mRNA and protein, correctly process and present the HLA-A2.1-restricted immunodominant MART-1 peptide (MART-1(27-35)), and serve as potent stimulators of MART-1-specific CTL in vitro. A replication-defective E1-deleted adenovirus (AdV) was constructed that expresses MART-1 (AdVMART1). Transduced DC produce full length MART-1 mRNA as well as MART-1 protein. AdVMART1 does not significantly down-regulate cell surface class I expression despite having an intact E3 region. Transduction of an HLA-A2-positive/MART-1-negative cell line with AdVMART1 renders these cells sensitive to lysis by CTL specific for the MART-1(27-35) immunodominant peptide. In addition, DC transduced with AdVMART1 stimulated MART-1(27-35)-specific tumor-infiltrating lymphocytes to synthesize IFN-gamma. Finally, AdVMART1-transduced DC were able to generate MART-1(27-35) peptide-specific, class I-restricted CTL in PBL cultures from normal donors. This study supports the use of tumor Ag-engineered DC in genetic immunotherapy.

Adenoviridae↗
PubMed1998

Cyclophosphamide, methotrexate, and chronic oral tegafur modulated by folinic acid in the treatment of patients with advanced breast carcinoma.

BACKGROUND: Chronic oral tegafur (a 5-fluorouracil prodrug) modulated by folinic acid has antitumor activity in patients with metastatic breast carcinoma resistant to 5-fluorouracil or doxorubicin-based regimens. In this study, bolus 5-fluorouracil was substituted with chronic oral tegafur and folinic acid in a cyclophosphamide, methotrexate, and 5-fluorouracil-based regimen to study the activity of this novel regimen in patients with advanced breast carcinoma. METHODS: This study was comprised of patients with advanced breast carcinoma and measurable or evaluable disease. Patients with prior chemotherapy were eligible. The regimen was comprised of cyclophosphamide, 600 mg/m2, and methotrexate, 40 mg/m2, both given intravenously on Day 1, and tegafur, 750 mg/m2, with folinic acid, 45 mg/day, both given orally in 3 daily fractions on Days 2-14, every 3 weeks. RESULTS: Forty-seven patients were included, 44 of whom were fully assessable. Three patients (7%) achieved a complete remission and 17 (38.6%) achieved a partial remission, for an objective response rate of 45.5% (95% confidence interval, 29-59%). The median duration of response was 11 months. In previously untreated patients the response rate was 54.5%. In patients previously treated with anthracycline or 5-fluorouracil-based regimens the response rates were 41% and 39%, respectively. Sixteen patients (36.4%) had disease stabilization. The median overall time to progression was 10 months. Toxicities usually were mild and were comprised of leukocytopenia, mucositis, emesis, and diarrhea. CONCLUSIONS: Chronic oral tegafur and folinic acid combined with intravenous cyclophosphamide and methotrexate at the dose and schedule used in the current study has significant antitumor activity both as first-line chemotherapy as well as in other patients with advanced breast carcinoma who had prior chemotherapy. This regimen is well tolerated, with gastrointestinal toxicity being the most frequent and dose-limiting toxicity.

Administration, Oral↗
PubMed1997

In vivo therapy of hepatocellular carcinoma with a tumor-specific adenoviral vector expressing interleukin-2.

A recombinant adenovirus (AdVAFP1-IL2) containing the murine alpha-fetoprotein (AFP) promoter was constructed to direct hepatocellular carcinoma (HCC)-specific expression of the human interleukin-2 (IL-2) gene. In vitro testing of AdVAFP1-IL2 showed HCC-specific IL-2 gene expression three to four orders of magnitude higher in AFP-producing HCC lines compared to non-AFP producing non-HCC lines. The in vivo efficacy and tumor specificity of AdVAFP1-IL2 was evaluated compared to AdVCMV-IL2 (in which the IL-2 gene is driven by the strong constitutive cytomegalovirus promoter) in the treatment of established human HCC (Hep 3B/Hep G2) xenografts growing in CB-17/SCID mice. Intratumoral injection of AdV resulted in growth retardation and regression in a majority of established hepatomas, but with a much wider therapeutic index and less systemic toxicity using the AFP vector. This study illustrates the superiority of using transcriptionally targeted recombinant AdV vectors in cytokine-based gene therapy.

Adenoviridae↗
PubMed1997

Carboplatin-based versus cisplatin-based chemotherapy in the treatment of surgically incurable advanced bladder carcinoma.

BACKGROUND: The carboplatin-based chemotherapeutic regimen M-CAVI (methotrexate, carboplatin, and vinblastine) is active against bladder carcinoma and can be administered to patients who are ineligible to receive cisplatin or doxorubicin. The authors designed a randomized study to evaluate whether M-CAVI offers a therapeutic advantage over the cisplatin-based regimen M-VAC (methotrexate, vinblastine, doxorubicin, and cisplatin) in the treatment of patients with surgically incurable advanced bladder carcinoma. METHODS: Patients with surgically incurable advanced bladder carcinoma were enrolled on a randomized trial comparing M-CAVI, which consists of carboplatin (300 mg/m2 on Day 2, adjusted using Calvert's formula for an area under the curve of 5), methotrexate (30 mg/m2 on Days 1, 15, and 22), and vinblastine (3 mg/m2 on Days 2, 15, and 22) administered every 28 days, versus standard M-VAC. The eligibility criteria included histologically proven bladder carcinoma, surgically incurable disease, and no prior chemotherapy. Patients were treated until disease progression or unacceptable toxicity occurred. RESULTS: From January 1989 to January 1994, 47 assessable patients were included. Seventeen patients had lymph node disease and 30 had distant metastatic disease. Twenty-three patients were randomized to receive M-CAVI and 24 to receive M-VAC. Patient characteristics in the two groups were similar. Overall response rates were 39% (95% confidence interval [CI], 20-62%) for M-CAVI and 52% (95% CI, 30-73%) for M-VAC (P = 0.3), with 3 complete responses observed among patients treated with M-VAC and none among those in the M-CAVI group. M-VAC was associated with more gastrointestinal toxicity, stomatitis, alopecia, and Grade 4 neutropenia than M-CAVI. One toxicity-related death occurred in the M-VAC group. There was a statistically significant difference in median disease-related survival time favoring M-VAC (16 months; range, 6 to 22+) versus M-CAVI (9 months; range, 6 to 14+) (P = 0.03). CONCLUSIONS: M-CAVI is less toxic but less active than M-VAC in the treatment of patients with advanced bladder carcinoma. Carboplatin-based regimens in which carboplatin is administered at the dose range used in the current study should be reserved for patients who cannot tolerate cisplatin treatment. Further research is required to assess the impact of high dose carboplatin in the treatment of this disease.

Adult↗
PubMed1997

Genetic immunization for the melanoma antigen MART-1/Melan-A using recombinant adenovirus-transduced murine dendritic cells.

Dendritic cells (DCs) are professional antigen-presenting cells that process and present antigenic peptides and are capable of generating potent T-cell immunity. A murine tumor model was developed to evaluate methods of genetic immunization to the human MART-1/Melan-A (MART-1) melanoma antigen. A poorly immunogenic murine fibrosarcoma line (NFSA) was stably transfected with the MART-1 gene. This transfected tumor [NFSA(MART1)] grows progressively in C3Hf/Kam/Sed (H-2k) mice. Partial protection against a challenge with NFSA(MART1) could be achieved with i.m. injections of a MART-1 expression plasmid or with systemic administration of an adenovirus vector expressing MART-1. However, superior protection was achieved when granulocyte macrophage colony-stimulating factor/interleukin-4-differentiated murine DCs transduced with an adenovirus vector expressing MART-1 were used for immunization. Both partial and complete protection could be achieved with i.v. administration of MART-1-engineered DCs. Splenocytes from immunized mice contained MHC class 1-restricted CTLs specific for MART-1. This preclinical model of genetic immunization supports a therapeutic strategy for human melanoma.

Adenoviridae↗
PubMed1997

[Dementias in the primary care setting].

OBJECTIVE: To study the epidemiological, demographic, social and family, and clinical variables of the population suffering dementia in our health district. DESIGN: A retrospective evaluation of medical records. SETTING: A rural health district. PATIENTS: All those patients with a diagnosis of dementia in 1995. MEASUREMENTS AND RESULTS: The evaluation was based on primary care medical records. The prevalence of dementia in the over-65s ranged, according to the population group, between 1.29 and 5.19 per 100 inhabitants. 90.2% of patients with dementia remained living at home. Their average age was 79.8 (SD, 7.4). 57% had Alzheimer's disease. 40% were in advanced stages of the disease (stage III and IV). Only 26% of the patients were referred to Neurology in 1995. 35% of the patients took no medication for their dementia. 45.6% were included in a home care programme. The main carer was the son or daughter in 47.8% of cases. Expectation of life from when dementia was diagnosed was 5.53 (SD 4.64) years. Patients with dementia died in their own homes in 47% of cases, the main cause of death being infection. CONCLUSIONS: In our rural environment most patients with dementia remained with their families. In most cases the aetiological diagnosis of dementia could be made from primary care.

Age Distribution↗
PubMed1997

Feasibility trial of high-dose 7-day continuous-infusion ifosfamide given on an outpatient basis.

High-dose ifosfamide (HD-IFX) has shown significant antitumor activity in advanced sarcoma and breast carcinoma. The use of uroprotective agents and the availability of ambulatory continuous-infusion pumps has allowed dose escalation in the administration of ifosfamide (IFX) on an outpatient schedule. We report the results of a phase II trial of IFX given at high doses to heavily pretreated patients. IFX was infused at 2 g/m2 per day for a total of 7 days through a central venous access, with cycles being repeated every 21 days. Mesna was given concomitantly at equimolar doses. No hematopoietic support was used. A total of 27 heavily pretreated patients whose disease had progressed during conventional-dose chemotherapy were included (14 sarcomas, 10 breast carcinomas, and 3 bladder carcinomas). Reversible neutropenia and gastrointestinal toxicity were the most frequently encountered toxicities. Only two patients developed transient renal failure, and two others developed central nervous system toxicity. No treatment-related death was observed. Of 22 patients who were evaluable for response, 6 (27%) showed an objective response (OR), all ORs being partial responses (PRs) with a median duration of 6 months, and 12 patients had stable disease (SD; 55%) with a median duration of 3.5 months. The median overall survival (OS) was 6 months. Three patients underwent high-dose chemotherapy after showing a response to our IFX schedule. We conclude that continuous-infusion IFX given in an outpatient setting is a feasible and active regimen that produces, a manageable toxicity profile in heavily pretreated breast cancer and sarcoma patients. Early institution of this schedule in less advanced stages could improve the results obtained.

Antineoplastic Agents, Alkylating↗
PubMed1997

Hyperphosphatasemia: CT assessment.

Hyperphosphatasemia is a rare disorder of uncertain cause. A 39-year-old male exhibiting striking skeletal deformities consisting of enlargement of the skull, enlargement and bowing of the long bones, neurosensorial symptoms and elevated alkaline phosphatase is the subject of this report. In the past, the radiological workup has been limited to plain films. We advocate CT in the assessment of neurological signs and symptoms which may complicate this disease.

Adult↗
PubMed1997

How important is hepatitis C virus (HCV)-infection in persons with acute leukemia?

Hepatitis C virus (HCV)-infection is common in persons with leukemia. Blood transfusions are the typical source and HCV-related chronic hepatitis a common outcome. Development of HCV-infection and -related hepatitis raises important questions about subsequent leukemia treatment including the natural history of the infection and need for treatment modification. Although the natural history of HCV-infection and -related hepatitis in this setting is unknown, data from normal persons with HCV-infection suggest that short-term survival is not likely to be decreased in persons with leukemia and these complications. In contrast, long-term survival may decrease because of a high rate of chronic hepatitis, cirrhosis, and possibly hepatocellular carcinoma. There are no convincing data that HCV-infection or -related hepatitis or alterations in anti-leukemia drug dose or schedule prompted by abnormal liver function tests, alter leukemia outcome. Consequently, it is uncertain whether drug doses and/or schedule should be modified in persons with leukemia and HCV-infection or -related hepatitis. Short-term outcome of blood cell and bone marrow transplants is also unaffected by HCV-infection or -related hepatitis.

Acute Disease↗
PubMed1997

Life-threatening toxicity of oral tegafur-uracil (UFT) plus leucovorin.

UFT. a a combination of tegafur and uracil, is increasingly used in the treatment of gastrointestinal malignancies. We report on a life-threatening toxicity observed in a 74-year-old female while undergoing adjuvant treatment with oral UFT plus leucovorm for adenocarcinoma of the rectum. The patient developed grade 4 thrombocytopenia, grade 4 neutropenia, grade 3 infection, grade 3 neurotoxicity and grade 2 cutaneous toxicity. This oral double-agent regimen should be used with caution in the adjuvant treatment of elderly patients with gastro-intestinal malignancies.

Administration, Oral↗