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Biomedical subjects

B Lathan

Publications and source records attributed to B Lathan.

At least 19 recordsLinked to original sources
PubMed1994

Effect of medium exchange rate on colony growth of the human tumor cell line MDA-231 cloned within the perfused capillary cloning system.

The conventional human tumor stem cell assay is limited by the lack of flexibility for drug scheduling with single agents and its inability to test drug combinations. Recently, we described the cloning of tumor cell lines within porous glass capillary tubes which allow free exchange of substances. The present study describes the influence of various perfusion modalities on the colony growth of the human tumor cell line MDA-231 cloned within the perfused capillary cloning system (PCCS). Colony growth of tumor cells within the PCCS is strongly dependent on perfusion tube volume, flow rate and duration of perfusion with growth medium. Best colony growth was achieved using a perfusion tube volume of 12 ml resulting in a cloning efficiency of 36.3%. Continuous perfusion with fresh medium did not improve the cloning efficiency; in fact, colony growth was hampered compared to colony growth within unperfused porous capillaries. However, cloning efficiency was acceptable when continuous perfusion was started at day 6 (26.4%) instead of day 0 (17.2%), or when a short perfusion with high volume (12 ml/h) was discontinued after 1 h at day 0. In contrast to the conventional capillary cloning system the PCCS has the potential for investigating secretion and kinetics of tumor-specific factors and the effect of growth-stimulating or growth-inhibiting drugs.

Breast Neoplasms↗
PubMed1994

Dexa-BEAM in patients with Hodgkin's disease refractory to multidrug chemotherapy regimens: a trial of the German Hodgkin's Disease Study Group.

PURPOSE: A prospective phase II study was conducted to evaluate the efficacy of dexamethasone, carmustine, etoposide, cytarabine, and melphalan (Dexa-BEAM) as salvage chemotherapy for patients with Hodgkin's disease. PATIENTS AND METHODS: Fifty-five patients progressing on or relapsing after eight- or 10-drug chemotherapy (cyclophosphamide, vincristine, procarbazine, and prednisone plus doxorubicin, bleomycin, vinblastine, and dacarbazine [COPP+ABVD] or COPP+ABV+ifosfamide, methotrexate, etoposide, and prednisone [IMEP]) were treated with Dexa-BEAM. Patients who responded after two cycles of Dexa-BEAM either continued treatment for another two to three cycles or received high-dose chemotherapy/autologous bone marrow transplantation (HDCT/ABMT) with cyclophosphamide, etoposide, and carmustine (BCNU) (CVB) as conditioning regimen. RESULTS: Seventeen patients (31%) achieved a complete remission and 16 (29%) a partial remission, resulting in a response rate of 60% (95% confidence interval, 46% to 73%). Progressive disease developed in 18 patients. Toxicity of Dexa-BEAM was acceptable with pronounced, but temporary World Health Organization (WHO) grade III/IV granulocytopenia and thrombocytopenia occurring in more than 90% of all courses. Two patients died of sepsis during granulocytopenia. Three prognostic subgroups could be distinguished: (1) patients progressing on initial chemotherapy, (2) patients relapsing within 12 months, and (3) patients with late relapses. The response rates for these groups were 52%, 60%, and 83%, and the median survival duration 12, 29, and 40+ months, respectively. In a nonrandomized comparison, the survival of patients who responded to two cycles of Dexa-BEAM and had additional cycles of Dexa-BEAM (n = 14) was not different from those responding patients who underwent HDCT/ABMT (n = 19). However, the power to detect a 20% survival difference was only 33% in this comparison. CONCLUSION: Dexa-BEAM is an effective salvage treatment for patients with Hodgkin's disease who fail to respond to multidrug chemotherapy. Efficacy and toxicity are comparable to HDCT/ABMT and underline the need for prospective randomized trials to define better the role of HDCT with and without ABMT in these patients.

Adult↗
PubMed1993

Immunohistochemical detection of P-glycoprotein in normal and malignant tissues: a comparative study of three monoclonal antibodies, JSB-1, C 219 and 265/F4, against different epitopes using frozen and paraffin tissue sections.

In this study, the reactivity of three different monoclonal antibodies (MAbs) against the multiple-drug resistance (MDR)-related P-glycoprotein (P-170) were compared with each other using a collection of frozen and paraffin-embedded tumors, normal tissues and metastatic cells of malignant pleural and peritoneal effusions. The MAbs JSB-1, C 219 and 265/F4 were used in an indirect immunoperoxidase technique on frozen material. In addition, MAb C 219 was used on formalin-fixed, paraffin-embedded material from the same tumors, of which frozen sections were studied, and in a retrospective study C 219 was tested on paraffin blocks of the primary tumors that were responsible for the malignant effusions. The results show different staining patterns for all three MAbs to some extent. Results in frozen and paraffin sections obtained with MAb C 219 were comparable. MAb C 219 performs well both in frozen and formalin-fixed, paraffin-embedded material, making it a useful candidate for application in routine laboratory analysis. The retrospective analysis did not show consistency of P-170 expression in the same patients. This leads to the hypothesis that the actual status of P-170 expression in recurrent disease should be obtained before continuing or modifying chemotherapy. Clinical studies aimed at the correlation of immunohistochemistry with therapy response have to evaluate the relevance of P-170 expression in drug resistance of primary and metastatic tumors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

High-dose versus intermediate dose cytosine arabinoside combined with mitoxantrone for the treatment of relapsed and refractory acute myeloid leukemia: results of an age adjusted randomized comparison.

193 patients with relapsed or refractory acute myeloid leukemia (AML) were entered into a prospective randomized comparison of high-dose versus intermediate dose cytosine arabinoside (AraC) both combined with mitoxantrone (mitox) according to the previously established sequential HD-AraC/mitox regimen (S-HAM). AraC was administered by 3 hr inf. q 12 hrs on days 1, 2, and 8, 9 at randomly assigned doses of either 3.0 versus 1.0 g/m2 in pts. < 60 years of age or 1.0 versus 0.5 g/m2 in older pts. Mitox was given to all cases at a dose of 10 mg/m2/d on days 3, 4, and 10, 11. Randomization was stratified for primary refractoriness against induction therapy and the length of first remission in relapsed cases (< 6 mths., 6-18 mths., > 18 mths.). From 151 presently evaluable cases 72 pts (48%) achieved a complete remission (CR), 38 cases (25%) were non-responders (NR) and 41 pts. (27%) died within the first 6 weeks after the start of treatment (early death = ED). No significant differences were found in CR rates being 52% and 44% for the 3.0 versus 1.0 g/m2 AraC regimens in pts. < 60 years and 48% and 45% after 1.0 versus 0.5 g/m2 AraC in older pts. No differences between the respective regimens emerged either for the time to CR (median 46 days) nor remission duration (median 4.5 mths). Analysis of treatment failures, however, demonstrated a significantly higher rate of NR after the lower dose regimens in both age groups of 41% and 32% versus 11% and 14% in pts. receiving AraC at higher doses (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Cloning of human tumor cell lines in porous glass capillary tubes: a further development of the human tumor stem cell assay.

The conventional human tumor stem cell assay for cloning tumor cells for drug sensitivity testing is limited by its inability to test drug combinations. In an attempt to overcome this limitation, we cloned tumor cell lines within porous glass capillary tubes. In contrast to plastic porous tubes, the porous glass membranes were transparent, and colony formation could be judged on an inverted microscope. Human as well as animal cell lines showed sufficient colony growth. Colonies formed within these porous tubes were homogeneously distributed, and their morphology was similar to those formed in the common stem cell assay. Cloning efficiency and colony size depended on the mean pore diameter of the glass membrane, with best colony growth within tubes with a pore diameter ranging from 8.5 nm to 14 nm. A linear relationship between number of cells seeded and number of grown colonies could be demonstrated for the cell lines MDA-231 and Colo 201. Colony growth achieved within porous glass capillary tubes is comparable to that achieved in Petri dishes and in nonporous tubes. We conclude that the porous capillary cloning system meets the basic suppositions for a quantitative cloning assay. Moreover, the porosity of the glass membrane offers the possibility of variable perfusion of medium and drugs. Further investigations will focus on various perfusion modalities and chemosensitivity testing.

Animals↗
PubMed1992

Cellular kinetics of prednimustine versus chlorambucil plus prednisolone in vitro.

Intracellular concentrations of prednimustine (PM), chlorambucil (CLB), phenylacetic acid mustard (PAAM) and prednisolone (P) were measured in different experimental tumor cell lines that had been incubated with either PM or CLB + P. For intracellular analytical determination, we modified a high-pressure liquid chromatographic method for the detection of these substances in plasma. Intact PM could be detected in the intracellular compartment of the incubated tumor cells. PM-incubated cells from PM-injected rats exhibited a higher intracellular concentration-time integral (PAAM) and longer concentration-time profiles for drugs with alkylating capacity than did cells exposed to the CLB + P mixture or to CLB. PAAM was not detectable after incubation of cells with PM, whereas in CLB-incubated cells the AUC of PAAM exceeded that of the parent drug CLB. Our in vitro results therefore favour the concept of a facilitated intracellular uptake and an increased antiproliferative effect for PM versus CLB and CLB + P.

Animals↗
PubMed1992

The clinical relevance of IgG subclasses in acute leukemias: low serum IgG as a risk factor for early death due to infection in acute myelogenous leukemia.

In order to investigate the clinical significance of IgG subclass levels in adult patients treated for acute lymphocytic (ALL) or myelogenous leukemias (AML), patients were tested before and in regular intervals during and after chemotherapy. Ten patients treated for acute lymphocytic leukemia had normal total IgG and IgG subclass levels that decreased under chemotherapy. This decrease was not associated with septic complications. In contrast, total IgG and subclass levels increased in most patients with acute myelogenous leukemia during chemotherapy and bone marrow aplasia. Those patients with newly diagnosed AML and low total serum IgG before treatment with intensive remission induction chemotherapy had, however, an increased risk of early death due to septic complications.

Adult↗
PubMed1992

The Second International Symposium on Hodgkin's Disease. Workshop III: Recommendations for future clinical trials.

In the opinion of the participants of the workshop, the following problems should be addressed with high priority: 1st, a clear definition of the 10%-15% of patients who should receive radiotherapy only; 2nd, reduction of toxicity of combined modality approaches for patients in localized stages with risk factors; and 3rd, definition of a poor-prognosis subgroup of patients in stages IIIB/IV for whom more efficient treatment programs must be developed. Dose intensification in the form of ABMT as the prominent example of high dose intensity should be tested in these patients. If this approach proves its efficacy, the concept of dose intensification could be extended to other patients with advanced disease. Results of recent trials in Hodgkin's disease suggest that the cure rates which increased considerably between 1960 and 1980 have reached a plateau. Further improvements that can be realistically expected will be small and studies to prove such progress need large numbers of patients ('megatrials') to avoid 'false negative' results. Such megatrials could be performed as large international or even intercontinental trials. To some extent, overviews could substitute for megatrials, if sufficient high-quality randomized studies addressing a specific question are available for a meta-analysis. The installation of an international steering committee was recommended, which should stimulate and coordinate world-wide efforts for the solution of the remaining problems in the treatment of Hodgkin's disease.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Combined effect of very early intensification and prolonged post-remission chemotherapy in patients with AML.

The study combines the effects of prolonged postremission chemotherapy with that of very early intensification. 900 adult patients at all ages with newly diagnosed AML uniformly received TAD for induction and consolidation followed by monthly myelosuppressive maintenance for 3 years. In patients of 60+ years with persistent bone marrow blasts a second TAD course was given. In all patients of less than 60 years a second induction course started on day 21 even in aplasia with no blasts. Second induction was randomly either TAD or HAM. In the younger age group 69% attained CR and similar in the two arms the CR rate after 5 years is 35%. Including the 50% patients attaining CR in the higher age group the CR rate after 5 years is 32%. In 40 patients receiving allogeneic BMT and 21 patients receiving autologous BMT in first CR relapse free survival is similar to that from chemotherapy alone in a matched pair analysis. We conclude that age adapted very early intensification followed by prolonged postremission chemotherapy represents a therapeutic progress.

Adolescent↗