Biomedical subjects
Publications and source records attributed to R Larsson.
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Suramin has shown promising antitumour activity against several tumour types, both in vitro and in vivo, but the clinical utility of this compound is hampered by its unfavourable toxicity profile. In the present study, the semi-automated fluorometric microculture cytotoxicity assay (FMCA) was employed for evaluation of the cytotoxicity of seven suramin analogues in vitro in a panel of human tumour cell lines and in primary cultures of tumour cells from patients. Like suramin, the analogues showed little sensitivity to resistance mechanisms involving P-glycoprotein, topoisomerase II, multidrug resistance associated protein and glutathione-mediated drug resistance. In the cell line panel, NF067 and FCE 26644 showed activity comparable with suramin. All analogues were less potent than suramin in patient cells except for FCE 26644. Correlation to suramin activity patterns in the cell line panel was highest for NF037 and low to moderate for the remaining analogues. In patient cells, high correlation coefficients were obtained for FCE 26644, NF110, NF031 and NF037. The results indicate that the cytotoxic activity of suramin on patient tumour cells is shared by the analogues with FCE 26644 being the most active. The pharmacophore for cytotoxicity in patient cells may be different from that observed in the cell lines.
The topoisomerase I inhibitors topotecan irinotecan (CPT-11) and its metabolite SN-38 were studied in a panel of cell lines and in primary tumour cells from patients, using a non-clonogenic cytotoxicity assay. All three substances showed similar activity patterns in the panel of cell lines established to classify the drugs mechanistically. In the patient tumour cells the drugs had different effects. In haematological and ovarian cancer samples, SN-38 was much more potent than topotecan, followed by irinotecan, while in colorectal cancer samples only irinotecan showed substantial activity. This in vitro activity pattern seems to agree with clinical experiences to date. The inactivity of SN-38 in colorectal cancer suggests irinotecan may also have some other role in addition to being a prodrug to SN-38. This study raises questions as to the role and relevance of early preclinical model systems in anticancer drug development, and suggests that important information can be obtained from studies using primary cultures of human tumour cells.
BACKGROUND: Chemotherapy using multi-drug regimens is considered more active than single-agent therapy. This may be due to synergistic interactions or, simply, a higher probability of administering an active agent. We investigated in vitro the type of drug interactions in a recognized regimen in relationship to tumour type and drug sensitivity. PATIENTS AND METHODS: The possibility of synergistic and additive interactions between individual cytotoxic drugs was investigated for the component drugs of the established FEC regimen, i.e., 5-fluorouracil, epirubicin and cyclophosphamide, in 243 patient tumour samples representing various drug sensitivity using the non-clonogenic fluorometric microculture cytotoxicity assay. RESULTS: Using a cell survival of < or = 50% as a limit for drug activity and sample sensitivity, the overall response rates to the most active single drug (Dmax) and the combination were 56% and 64%, respectively, with a distribution among diagnoses similar to that in the clinic. For 86% of the samples there was concordance with respect to judgement of activity using either Dmax or the combination. For samples being sensitive to at least one single drug, 95% were also sensitive to the combination whereas for samples with insignificant Dmax effect, only 2% were sensitive to the combination. In samples with modest Dmax effects, i.e., cell survival in the range > 50%- < or = 80%, 45% responded to the combination. The effect of the combination was generally well predicted from the Dmax effect. CONCLUSIONS: The superior antitumour effect of drug combinations compared with single drugs may be due to the higher chance of selecting an active agent. However, for intermediately sensitive tumours, additional interaction effects of a combination may be of clinical significance.
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Inhalation of bacterial endotoxin induces an acute inflammation in the lower respiratory tract. In this study, the anti-inflammatory effects of the anti-oxidant N-acetylcysteine (NAC) and the glucocorticoid dexamethasone were investigated in mice exposed to aerosolized endotoxin (lipopolysaccharide (LPS)). Powerful reduction of neutrophils in bronchoalveolar lavage fluid (BALF) was obtained by a single i.p. injection of dexamethasone (10 mg/kg), whereas treatment with NAC only resulted in reduction of neutrophils when administered at a high dose (500 mg/kg). Measurement of cytokine and chemokine expression in lung tissue revealed a significant decrease of tumour necrosis factor-alpha, IL-1alpha, IL-1beta IL-6, IL- 12p40, and MIP-1alpha mRNA when mice where treated with dexamethasone but not when treated with NAC. Analysis of oxidative burst demonstrated a remarkable reduction of oxygen radicals in BALF neutrophils after treatment with dexamethasone, whereas the effect of NAC was not significantly different from that in untreated animals. In conclusion, dexamethasone exerted both anti-inflammatory and anti-oxidative effects in acute airway inflammation, probably by blocking early events in the inflammatory cascade. In contrast, treatment with NAC resulted in a weak reduction of the inflammatory response but no inhibition of proinflammatory cytokines or reduction of oxidative burst in neutrophils. These results demonstrate dramatic differences in efficiency and also indicate that the two drugs have different actions. Combined treatment with NAC and dexamethasone revealed an additive action but no synergy was observed.
BACKGROUND: Smoking is an important risk factor for cardiovascular and cerebrovascular complications in patients with chronic kidney failure. Very high plasma nicotine concentrations have been reported in patients with severe kidney failure, indicating that the disposition of nicotine in these patients may be different. The purpose of this study was to assess the pharmacokinetics of intravenously administered nicotine in healthy subjects and in patients with kidney failure. METHODS: Nine healthy subjects (glomerular filtration rate [GFR], 84 to 143 mL/min/1.73 m2), four patients with mild kidney failure (GFR, 63 to 73 mL/min/1.73 m2), five patients with moderate kidney failure (GFR, 18 to 36 mL/min/1.73 m2), and six patients with severe kidney failure (GFR, 1 to 10 mL/min/1.73 m2) were recruited. Three patients were treated with continuous ambulatory peritoneal dialysis. An intravenous infusion of nicotine (0.028 mg/kg) was given for 10 minutes. Nicotine and cotinine concentrations were measured in plasma, urine, and peritoneal dialysate from 0 to 24 hours after start of infusion RESULTS: There were significant correlations between GFR and total clearance, nonrenal and renal clearance of nicotine, area under the plasma concentration-time curve extrapolated to infinity, terminal elimination half-life, and mean residence time. Nonrenal clearance was 1303 mL/min and 661 mL/min in healthy subjects and patients with severe kidney failure, respectively. Only 1% to 2% of the nicotine dose was excreted unchanged in a 24-hour collection of peritoneal dialysate. The elimination of cotinine was also decreased in patients with kidney failure. CONCLUSION: Progressive kidney failure is associated with a gradual decrease of renal and nonrenal elimination of nicotine.
BACKGROUND: The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene determines the concentration of ACE in serum and local tissues. The role of this polymorphism in progressive chronic renal disease is still not fully clear. METHODS: We analysed the impact of the D/D polymorphism on the rate of decline in renal function in patients with non-diabetic, chronic progressive renal insufficiency. Seventy non-diabetic patients, aged 21-69 years at baseline, with moderately advanced renal insufficiency due to primary chronic renal disease were followed for an average of 3 years with repeated measurements of their glomerular filtration rate (GFR). Their mean GFR at baseline was 41 ml/min/1.73 m(2) body surface area (BSA). The polymerase chain reaction (PCR) amplification method was used to detect the I/D polymorphism of the ACE gene. GFR was measured as the clearance of (51)Cr-EDTA and the individual rate of progression was calculated using linear regression. RESULTS: The distributions of the genotypes were: D/D 30%, I/D 49%, and I/I 21%. The rates of progression in the three ACE genotype groups were an annual decline in renal function of -4.2 (SD 4.6) ml/minx1.73 m(2) BSA in the D/D group, -2.7 (SD 3. 4) in the I/D group and -1.7 (SD 3.4) in the I/I group (ANOVA P=0. 12). In patients with proteinuria below 3.5 g/24 h, the D/D group had a significantly higher rate of progression than patients with the I allele. The same was found in a separate analysis when only patients with normal apoliprotein B (below 155 mg/dl) levels were analysed. Furthermore, the D/D genotype was a significant predictor of a more rapid decline in renal function in male, but not female, patients. CONCLUSION: The results in this study in non-diabetic patients with chronic renal disease indicate that the presence of the D allele in the ACE genotype may be of particular importance as a predictor of a high rate of progression in male patients who otherwise do not have a major burden of documented and important prognostic factors for progressive renal insufficiency.
Recruitment of neutrophils to lung tissue and airspaces is a hallmark of inflammatory events following inhalation of endotoxins. We studied the role of different lymphocyte subsets in this inflammation, which is assumed to primarily involve the innate immune system. Inhalation of aerosolized Escherichia coli lipopolysaccharide (LPS) in mice induced a dose-dependent increase in neutrophils in bronchoalveolar lavage fluid, reaching a maximum after 12 h at a low dose and after 24 h at a high dose. Profiles of gene expression in lung tissue indicated an early (2 h) and transient onset of proinflammatory cytokines and chemokines by a low dose of LPS, while a high dose caused more delayed and sustained (6 to 12 h) activation. Gamma interferon, interleukin-2 (IL-2), RANTES, and the alpha chain of the IL-2 receptor were not expressed at a low dose, whereas a high dose of LPS induced a strong expression of these genes, indicating a dose-dependent activation of T cells. A similar pattern was observed for IL-17, supporting a contribution of T cells to the neutrophilic inflammation only at high-dose exposure to LPS. The involvement of lymphocytes in the inflammatory response was further studied using mice with functional deficiencies in defined lymphocyte subsets. Both gammadelta T-cell- and B-cell-deficient mice displayed a response similar to that of the corresponding wild-type strains. Selective depletion of NK cells by in vivo administration of the pk136 antibody did not significantly affect the recruitment of neutrophils into airspaces. Thus, neither NK cells, B cells, nor gammadelta T cells appeared to participate in the host response, suggesting that among the lymphocyte subsets, alphabeta T cells are exclusively involved in endotoxin-induced airway inflammation.
Islet transplantation offers a logical means to treat insulin-dependent diabetes. However, for reasons poorly understood, the clinical results with islet transplantation have been vastly inferior to those obtained with whole organ pancreas transplantation. The conventional technique for transplanting isolated islets is by intraportal injection, with the islets being trapped in the liver. Human islets exposed to human blood trigged an "instant blood mediated inflammatory reaction", IBMIR, characterised by platelet consumption, and activation of the coagulation and complement systems. The islets became surrounded by clots and infiltrated with leukocytes, and there was evidence of islet damage as reflected in insulin dumping. When heparin and a complement inhibitor (SCRI), was added to the system, IBMIR was suppressed and islet damage reduced. After intraportal pig-to-pig islet intraportal allotransplantation similar morphological changes was found, corroborating the in vitro findings. Thus, IBMIR inflicts a significant damage to human islets exposed to human blood and IBMIR will also, most likely, enhance the subsequent specific, cell mediated, rejection. Platelet and complement activation seem to be the most important factors in the pathogenesis of IBMIR. The results presented strongly suggest that IBMIR observed both in vitro and in vivo when isolated islets come in contact with blood could provide an explanation for the unsatisfactory results seen in clinical islet allotransplantation.
A new class of recently discovered antineoplastic agents, the pyridyl cyanoguanidines, exert a potent antitumor activity in rodents after oral administration. Optimization in vitro and in vivo has resulted in the selection of the lead candidate CHS 828 (N-(6-chlorophenoxyhexyl)-N'cyano-N"-4-pyridylguanidine). CHS 828 was found to exert potent cytotoxic effects in human breast and lung cancer cell lines, with lesser effects on normal fibroblasts and endothelial cells. In a study using a panel of cell lines with different resistance patterns, the effects of CHS 828 showed a low correlation with the activity patterns of known anticancer agents, and no sensitivity to known mechanisms of multidrug resistance was observed. In nude mice bearing human tumor xenografts, CHS 828, at doses from 20 to 50 mg/kg/day p.o., inhibited the growth of MCF-7 breast cancer tumors and caused regression of NYH small cell lung cancer tumors. Oral administration of CHS 828 once weekly improved efficacy without increasing toxicity. CHS 828 was found to compare favorably with established chemotherapeutic agents such as cyclophosphamide, etoposide, methotrexate, and paclitaxel. In mice with NYH tumors, long-term survival (>6 months) was observed after treatment with CHS 828 was stopped. In conclusion, CHS 828 is an effective new antitumor agent, with a potentially new mechanism of action. CHS 828 is presently being tested in Phase I clinical trials in collaboration with the European Organization for Research and Treatment of Cancer.
The cellular pharmacology of calcein acetoxymethyl ester (calcein/AM)-induced cytotoxicity was investigated in human tumor cell lines in order to identify tentative mechanisms of action. The activity profile in 10 cell lines with known mechanisms of resistance was compared with the activity profiles of standard drugs and experimental substances. The activity of calcein correlated with that of different topo II inhibitor/intercalating compounds and mitochondrial accumulating compounds, such as Rhodamine 123, Mito Fluor Green and Acridine Orange-10. Using U-937 GTB as a model cell line, calcein was found to distribute throughout the whole cell, nuclei and mitochondria included. In addition, studies of mitochondrial dehydrogenase activity and extracellular acidification rate showed an almost complete lack of dehydrogenase activity and extracellular acidification at 12 and 24 h, respectively. The results indicate that calcein/AM may induce cytotoxicity through interference with both mitochondrial and nuclear DNA.
Our aim is to study whether or not in vitro sensitivity of leukemic cells correlates with clinical effect; if so, in vitro testing might used for stratification of treatment. During 1995-1997 bone marrow samples from 145 Swedish children with newly diagnosed acute lymphoblastic leukemia were analysed by the automated fluorometric microculture cytotoxicity assay. Therapeutic effect was evaluated by bone marrow morphology day 15 and 29. Preliminary results indicate that marrow samples from patients with poor response to induction therapy show a higher degree of in vitro resistance to several cytotoxic drugs at diagnosis than good responders.
Since May 1996 all Nordic countries have been participating in a study of childhood acute myeloid leukemia (AML). The aim is to correlate the in vitro sensitivity of leukemic cells and individual plasma concentrations of cytotoxic drugs with clinical effect. Blast cells from bone marrow and/or peripheral blood are tested against a panel of cytotoxic agents using the fluorometric microculture cytotoxicity assay (FMCA). Plasma concentrations of cytotoxic drugs are analysed during induction therapy. Bone marrow samples from the participating centres generally reached the analysing laboratory within 24 hours. 61 out of 71 (86%) samples were successfully analysed, 47 de novo AML and 14 relapses. Relapsing patients tended to have a more resistant test profile than newly diagnosed patients. Steady state plasma levels of doxorubicin, etoposide and 6-thioguanine nucleotide varied about 10-fold between patients. The intra-individual variation was much less, suggesting that dose adjustment based on pharmacokinetic data might be useful in the future.
In order to further elucidate the roles of DNA topoisomerase II (topo II) subtypes, alpha and beta, as drug targets in chemotherapy, we have determined the enzyme levels in K562 cells selected for resistance to mitoxantrone (K562/Mxn), daunorubicin (K562/Dnr) and idarubicin (K562/Ida 20 and K562/Ida 60), as well as topo II-DNA complex formation, DNA damage and cytotoxicity, induced by topo II interactive agents, for example etoposide, teniposide, mitoxantrone and amsacrine. As compared to the parental cells, topo IIalpha/beta protein levels in K562/Mxn, K562/Dnr, K562/Ida 20 and 60 lines, measured with Western blot, were 17/67%, 85/88, 24/31% and 10/7% respectively. DNA damage, determined by DNA unwinding technique, induced by teniposide and amsacrine correlated with both topo IIalpha/beta protein levels (r2 = 0.8/0.9, P = 0.03/0.01 and r2 = 0.8/0.9, P = 0.04/0.01, respectively). Topo II-DNA complex formation induced by all studied drugs correlated with topo IIbeta protein levels (r2-range 0.8-0.9, P-range 0.01-0.04), while the correlation with topo IIalpha was weaker. Topo IIalpha/beta protein levels tended to show an inverse correlation with the cytotoxicity of etoposide (r2 = -0.9/-0.7, P = 0.01/0.06). The overall topo II-DNA complex formation correlated with drug-induced DNA damage (r2 = 0.9, P = 0.0001), whilst not with the cytotoxicity. Our findings indicate that both topo II isozymes are the targets of the antitumor agents studied, and of potential clinical relevance for prediction of treatment efficacy. They could play a role in tailored chemotherapy.
PURPOSE: In vitro tumor models could support the process of development of new cytotoxic drugs and selection of suitable drugs for the individual patient. We investigated whether the testing of tumor cells from patients with kidney or urinary bladder carcinoma by fluorometric microculture cytotoxicity assay (FMCA) could provide clinically relevant data for these tumor types. MATERIALS AND METHODS: A total of 45 tumor samples from patients with kidney or urinary bladder carcinoma were compared with 247 samples of other tumor types with respect to sensitivity to 8 standard and 6 investigational cytotoxic drugs in the FMCA, a 72 hour assay based on the concept of total cell kill. In bladder carcinomas, sensitivity to standard drugs was correlated to various tumor characteristics. RESULTS: The technical success rate for kidney and bladder carcinomas was high; approximately 90% of the samples could be analyzed successfully. Kidney carcinomas were highly resistant to standard drugs and bladder carcinomas essentially as sensitive as carcinomas of the breast and ovary but with a steeper dose-response relationship. In bladder carcinoma there was no clear relationship between tumor stage, grade, ploidy, mitoses or p53 expression and drug sensitivity. Except for suramin, kidney carcinomas were poorly sensitive to the investigational drugs CdA, gemcitabine, paclitaxel, vinorelbine and topotecan. In bladder carcinomas paclitaxel, gemcitabine and suramin showed promising activity. CONCLUSIONS: The FMCA seems suitable for cytotoxic drug sensitivity testing of urinary tract carcinomas. This technique may have a role in new drug development in these tumor types.
We have developed a versatile in vitro chamber model with a double purpose: first, to be able to study mechanisms of bio-incompatibility, and, second, to test biomaterials at all levels of interactions, in whole blood. The use of biomaterials in the form of microscope slides as walls in the chamber makes it possible to analyse both the biomaterial surface with regard to protein and cell binding, as well as the molecular events taking place in the fluid. Incubation of blood in the chamber, for 60 min at 37 degrees C resulted in the rapid binding of complement and coagulation proteins and of leukocytes and platelets to polyvinylchloride (PVC) slides. The cells formed a layer which more or less covered the underlying surface. Unlike complement activation, as reflected by soluble C3a and C5b-9, the thrombin-antithrombin formation was completely nullified in cell-depleted plasma. Despite the fact that thrombin-antithrombin generation was also negligible in platelet-rich plasma, inhibition of platelet aggregation on the material surface with aspirin resulted in suppressed generation of thrombin antithrombin complexes. Taken together, the coagulation activation in the chamber was dependent on the presence of blood cells which suggests that bound/aggregated platelets initiate a sequence of events involving leukocytes that results in coagulation activation.
The development of resistance to cytostatic agents is a serious obstacle to the success of cancer therapy and has been the focus of many research efforts. Traditionally, cell lines are selectively cultured in the presence of cytostatic agents and the biochemical and cytogenetic properties of the cell lines are then analyzed. In order to better understand the mechanisms by which drug resistance is mediated, we have analyzed three cell lines, each derived from the parent line K562, which are resistant to vincristine, mitoxantrone, or idarubicin, using comparative genomic hybridization (CGH). In each case, CGH successfully identified amplifications and/or deletions unique to the drug-resistant selected cell lines. Further characterization of the genetic regions identified in the CGH analysis could greatly contribute to our understanding of acquired drug resistance, and could potentially impact the clinical management of cancer.