Search PubMed⌕ Search

Biomedical subjects

M Gobbi

Publications and source records attributed to M Gobbi.

At least 145 records · Page 8Linked to original sources
PubMed1989

Targeting of a plasma cell line with a conjugate containing xanthine oxidase and the monoclonal antibody 62B1.

We report on the preparation of an antibody-conjugated enzyme consisting of xanthine oxidase, a free-radical-producing enzyme, linked to the 62B1 monoclonal antibody, which recognizes the last steps of differentiation of B cell lineage (plasma cell and hairy cells). The conjugate specifically kills target cells, retaining both enzymic and immunological properties, without any damage to normal myeloid clonogenic efficiency. The model is suitable for ex vivo bone marrow purging in multiple myeloma patients.

Animals↗
PubMed1989

Evidence that long-term bone marrow culture of patients with multiple myeloma favors normal hemopoietic proliferation.

Long-term bone marrow cultures (LTBMC) were initiated with marrow aspirate cells from 12 patients with multiple myeloma (MM) using the Dexter system. The myeloid and the neoplastic myeloma cell growths were evaluated for up to 6-9 weeks. Our results demonstrate the development of an adherent layer capable of supporting normal granulopoiesis with a concomitant drop in the growth of myeloma cells. The B lymphocyte monoclonal proliferative compartment was also studied with bromodeoxyuridine (Brdurd), an analog of thymidine incorporated during the S-phase, and the labeling index was calculated. The ability to form myeloma stem cell colonies in a modified plasma clot short-term assay was also evaluated. The results confirmed that the neoplastic B lineage compartment was not able to grow in Dexter's system for more than 4 weeks in 11 of 12 cases studied, with the disappearance of Brdurd-positive cells after two weeks, whereas LTBMC were able to sustain the growth of myeloid progenitors. These data indicate the potential applicability of this culture method in selecting normal hematopoietic progenitors from patients with multiple myeloma. This approach can have significant implications for aggressive treatment of patients with multiple myeloma, especially in trials involving autologous bone marrow transplantation (ABMT).

Adult↗
PubMed1989

S-phase evaluation with bromodeoxyuridine in lymphocytes from cattle infected with bovine leukemia virus (BLV).

Bromodeoxyuridine (BrdUrd), an analogue of thymidine, can be detected by means of monoclonal antibodies and utilized as a marker of the S-phase. In this paper a determination of the S-phase in BLV+ cattle with lymphocytosis has been performed by incorporating bromodeoxyuridine in the DNA. This evaluation was compared to the DNA content, demonstrating that i) bromodeoxyuridine incorporation is a reliable marker of S-phase in BLV+ cattle with lymphocytosis and ii) cytofluorimetry is the method of choice, together with immunocytochemistry, to demonstrate bromodeoxyuridine incorporation.

Animals↗
PubMed1989

Immunotoxins containing saporin 6 and monoclonal antibodies recognizing plasma cell-associated antigens: effects on target cells and on normal myeloid precursors (CFU-GM).

Monoclonal antibodies 8A and 62B1, recognizing plasma cell-associated antigens, were covalently linked to saporin 6, a ribosome-inactivating protein similar to the A-chain of ricin. Both immunotoxins were tested on target human cell lines U266 and Raji, on non-target K562 cell line and on myeloid CFU-GM progenitors. The cloning efficiency and viability of target cells were strongly reduced by 8A-saporin 6 and 62B1-saporin 6 immunotoxins, with an ID50 up to 200,000-fold lower than free saporin 6, whilst the K562 non-target cell line was unaffected. Normal human myeloid precursors (CFU-GM) were inhibited by immunotoxins only to a limited extent. An application of this model for autologous bone marrow transplantation in multiple myeloma patients is proposed. Since no eradication of cloning target cells was achieved by a single immunotoxin, mixtures made with different antibodies could help to reach this goal.

Animals↗
PubMed1989

Histology and immunohistology of bone marrow biopsy in multiple myeloma.

B5-fixed/paraffin-embedded Jamshidi needle biopsies from 125 multiple myeloma patients were reviewed according to both morphological and immunohistological criteria. At microscopic examination, the following parameters were evaluated: i) grade of malignancy (low = 56; intermediate = 50; high = 19); ii) growth pattern (interstitial +/- sheets/nodules = 90; nodular = 13; packed marrow = 18; sarcomatous = 4); III) histological stage (I = 64; II = 35; III = 26). Comparison of the findings in trephine biopsies and aspirates showed that in 30% of the cases the latter led to an underestimation of the tumor burden. Immunohistochemical determination of Ig easily allowed: i) differential diagnosis from exuberant reactive plasmacytosis; ii) recognition and counting of neoplastic plasma cells; iii) detection of minimal residual disease after treatment. Immunohistochemistry also confirmed phenotypic aberration of neoplastic plasma cells, showing positivity for CD45, EMA, and cytokeratins in 14%, 59%, and 25% of the cases, respectively. Furthermore, it displayed expression of the P-glycoprotein in 4/8 resistant cases. These findings underline that routinely processed Jamshidi needle biopsies can be of great value in the study of patients with multiple myeloma.

Acute Disease↗
PubMed1989

Improvement of Durie & Salmon staging for multiple myeloma by adding platelet count as a stratifying variable: a multivariate regression analysis of 163 untreated patients.

The presenting clinical features of 163 previously untreated patients with multiple myeloma were correlated with survival duration using univariate and multivariate regression analyses. The univariate proportional hazard analysis ranked the parameters in the following order of importance: platelet count, haemoglobin level (Hb), tumour cell mass stage, lytic bone lesions, creatinine and age. When the individual contribution of each variable was assessed by multivariate regression analysis, platelet count was confirmed to be the dominant feature for prognosis, while clinical stage provided additional information. The introduction of platelet count could then be used to improve the discriminating power of Durie & Salmon staging, by allowing separation of the high-risk group (stages II and III) into a smaller subgroup (22%) of thrombocytopenic patients (less than 150 x 10(9) platelets/l) whose risk of death was actually very high (median survival: 9 months) and a larger subgroup (46%) of patients with normal platelet count and intermediate or standard risk (median survival: 48 months).

Humans↗
PubMed1989

Autologous bone marrow transplantation with immunotoxin-purged marrow for advanced multiple myeloma.

A system to purge the bone marrow of myeloma cells has been developed in our laboratories with the aim of treating with myeloablative radiochemotherapy patients suffering from advanced multiple myeloma. This system is based on the ex vivo incubation of the marrow with an immunotoxin composed of the 8A monoclonal antibody--that recognizes plasma cells and B-cell precursors--and the ribosome-inactivating protein momordin. 8 patients have so far been treated. 4 are surviving from 4 to 18 months after ABMT, whereas 4 died after 1 to 6 months, 2 from infections, 1 from relapsing disease and 1 from veno-occlusive disease. A marked tumour reduction was observed in all evaluable patients; however, none has achieved complete disappearance of the disease. The haemopoietic reconstitution was significantly delayed in 3 patients. These preliminary results show the feasibility of this approach in advanced MM patients with heavily infiltrated marrow. The place of ABMT in the treatment of MM remains to be determined; the selection of patients with still responding and less advanced disease would probably produce better results.

Adult↗
PubMed1989

High-dose chemoradiotherapy and allogenic bone marrow transplantation in multiple myeloma.

17 patients with multiple myeloma (MM) received marrow transplants from their HLA-matched, MLC-negative sibling donors. 9 patients had progressive disease not responding to conventional treatments, while the other 8 patients were rated as responders. The most frequently used conditioning regimen consisted of total body irradiation and high-dose, multi-agent chemotherapy with cyclophosphamide plus either oral melphalan (5 cases) or BCNU (1 case) on both these drugs (7 cases). 12 patients were evaluable for response to BTM: 7 of them (6 responders and 1 with advanced refractory MM) entered complete remission, while 5 had a sustained decrease in tumor mass that ranged between 72% and 93%. 11 patients died of transplant-related causes, 1 of them with signs of progressive disease. The remaining 6 patients are alive and 5 of them maintain a complete remission status 4 to 67 (median 36) months after BMT. It is concluded that therapeutic benefits of transplantation in MM are still offset by the high mortality related to the procedure. A more accurate selection of patients who would most benefit from BMT and performing transplant at an earlier phase of the disease are warranted before major advances can be made in the cure of these patients.

Adult↗
PubMed1989

In-vivo (+)-[3H]fenfluramine binding to rat brain: biochemical and autoradiographic studies.

The in-vivo binding of (+)-[3H]fenfluramine to rat brain regions is saturable, as shown by the inhibition curves obtained by co-injecting increasing concentrations of unlabelled (+)-fenfluramine: at 2.5 mg kg-1 the inhibition of total bound radioactivity was maximal in all regions. The regional distribution of (+)-[3H]fenfluramine specific binding sites (hypothalamus greater than striatum = cortex greater than brainstem greater than hippocampus greater than cerebellum) closely parallels the regional distribution of 5-hydroxytryptamine uptake. Computer-assisted quantitative autoradiography confirms these findings. The IC50 of (+)-fenfluramine for inhibition of its binding in-vivo is below 0.25 mg kg-1, compatible with the presence of high affinity sites. While the physiological role of (+)-[3H]fenfluramine binding sites in the brain, particularly in hypothalamic nuclei, is being investigated, it has been found that in-vivo labelling could also be obtained in the periphery, in lung and renal cortex. The possibility that this peripheral binding is due to the presence of blood platelets cannot be ruled out.

Animals↗
PubMed1989

Normal myeloid progenitors (CFU-GM) in multiple myeloma: a preliminary study in view of autologous BMT.

Normal granulocyte-macrophage precursors (CFU-GM) were studied in 65 multiple myeloma patients by means of culture assays. The patients were divided into separate groups on the basis of previous therapy (i.e. analysis performed at diagnosis or after chemotherapy), time elapsed from the last therapy (i.e. more or less than 1 month) and clinical features of the disease (i.e. tumor stage, immunoglobulin type, bone marrow plasma cell infiltration). The results were evaluated by Wilcoxon rank sum test and linear regression analysis. There was no statistical difference in CFU-GM cloning efficiency or in the number of CFU-GM/ml of bone marrow, even though a larger CFU-GM recovery was found in patients evaluated at diagnosis or at least 1 month or more from previous chemotherapy. In addition, no correlation was demonstrated between bone marrow plasma cell percentage and CFU-GM cloning efficiency. This finding was confirmed by the number of myeloid bone marrow cells in S-phase, assessed by the bromodeoxyuridine labeling index, which showed similar results in patients with different degrees of plasma cell infiltration. In conclusion our data indicate that the granular-monocytic lineage keeps its cell-line potentiality regardless of the degree of marrow plasma cell infiltration and the type of therapeutic approach. These data suggest that autologous bone marrow transplantation might be feasible even in patients with a large neoplastic infiltration.

Adult↗
PubMed1989

Allogeneic bone marrow transplantation for multiple myeloma.

Seventeen patients received marrow transplants from their HLA-matched, MLC-negative, sibling donors. Nine patients had progressive disease not responding to conventional treatments, while the other 8 patients were rated as responders. The most frequently used conditioning regimen consisted of total body irradiation and high-dose multi-agent chemotherapy with cyclophosphamide plus either oral melphalan (5 cases) or BCNU (1 case) on both these drugs (7 cases). Twelve patients were valuable for response to BTM: 7 of them (6 responders and 1 with advanced refractory MM) entered complete remission, while 5 had sustained decrease in tumor mass that ranged between 72% and 93%. Eleven patients died of transplant-related causes, 1 of them with signs of progressive disease. The remaining 6 patients are alive and 5 of them maintain a complete remission status 4 to 67 (median 36) months after BMT.

Adult↗
PubMed1989

Prognostic variables and clinical staging in multiple myeloma.

To evaluate the most important factors in the prognosis and staging of multiple myeloma (MM), the presenting clinical features of 163 previously untreated patients with MM were correlated with survival duration using univariate and multivariate regression analyses. The univariate proportional hazard analysis ranked the parameters in the following order of importance: platelet count, hemoglobin level (Hb), tumor cell mass stage, lytic bone lesions, creatinine, and age. When the individual contribution of each variable was assessed by multivariate regression analysis, platelet count was confirmed to be the dominant feature for prognosis and clinical stage provided additional information. The introduction of platelet count could then be used to improve the reliability of the Durie and Salmon staging, by allowing to separate the high-risk group (stages II and III) into a smaller subgroup (22%) of thrombocytopenic patients (less than 150 x 10(9) platelets/L) whose risk of death was actually very high (median survival, 9 months) and a larger subgroup (46%) of patients with normal platelet count and intermediate or standard risk (median survival, 48 months). This simple change in the prognostic system gave rise to markedly different survival curves also after the exclusion of patients with renal failure and applied successfully to both old and young patients (greater than and less than 50 years, respectively). Finally, platelet count, Hb, and lytic bone lesions could be combined simply to stratify patients with normal renal function into three risk groups: (1) low (39% of cases; median survival, 79 months), (2) intermediate (53% of cases; median survival, 48 months), and (3) high (8% of cases; median survival, 19 months).

Bone Marrow↗
PubMed1988

A sensitive test for the detection of NK activity. Plasma clot clonogenic assay.

Natural killer (NK) activity, which has been implicated in the immune response against viral infections and neoplasias, is currently evaluated by means of a chromium (51Cr) release assay. However, criticisms have been raised with regard to the reliability and reproducibility of the test. We have developed a different in vitro method for measuring NK activity, based on the inhibition of the target clone growth in plasma clot semisolid medium. This method overcomes the limitations inherent to the 51Cr release test and more closely mimics the in vivo situation. The inhibitory activity revealed by the cloning assay was always greater than the lytic activity in the 51Cr release assay. Moreover, effector/target ratios of 3:1 and 1.5:1 still produced clonal inhibition. B-CLL cells, used as effectors, showed no inhibitory activity and the Raji cell line employed as target was resistant in both techniques. Thus, the clonogenic assay appears to be more sensitive for the evaluation of low levels of NK activity, for basic studies on the effector/target interactions, for the evaluation of LAK cell activity, and in diseases in which an involvement of the NK compartment has been hypothesized.

Blood Coagulation↗
PubMed1988

In situ staining of bromodeoxyuridine positive cells in normal and neoplastic colony-forming units grown on plasma clots.

Bromodeoxyuridine, an analogue of thymidine, can be detected by means of monoclonal antibodies and utilized as a marker of the S-phase of the cell cycle. In this paper a method for the detection of the labeling index of normal and neoplastic colony-forming units (CFU) growing in plasma clot semisolid medium is described and preliminary results on the cell cycle of 7th and 14th CFU granulocyte-macrophage are discussed.

Blood Coagulation↗
PubMed1988

Improvement of human myeloma stem cell growth in a liquid culture system supplemented with phytohemagglutinin.

A highly efficient cloning system for in vitro myeloma colony growth could be valuable for screening antineoplastic agents in resistant patients and for testing the effects of purging methods in the context of autologous bone marrow transplantation. In this paper we report the results of experiments intended to improve the myeloma cloning system in plasma clot originally described by Ludwig et al. We tested the effects of the addition of phytohemagglutinin (PHA), coupled with a transformation of the original plasma clot method into a liquid culture system. A statistically higher number of myeloma colonies was observed in the liquid system in the presence of PHA (20 cases, median 84.5 vs. 9.5; p = 0.005), whereas a single variant (either PHA alone or liquid system alone) did not determine any significant growth variation. The increase in the cloning efficiency was evident even in the cases characterized by low bone marrow plasma cell infiltration, suggesting that this method is suitable for the described purposes.

Bone Marrow Cells↗