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Biomedical subjects

G Toffoli

Publications and source records attributed to G Toffoli.

At least 37 records · Page 2Linked to original sources
PubMed1998

Role of folate receptor and reduced folate carrier in the transport of 5-methyltetrahydrofolic acid in human ovarian carcinoma cells.

Folate receptor-alpha (FR-alpha) is generally over-expressed in non-mucinous human ovarian carcinomas. The meaning of FR-alpha over-expression and its role in the 5-methyltetrahydrofolic acid (N5-CH3-H4PteGlu) transport in such tumors is not clear, especially compared with the reduced folate carrier (RFC), the other known folate transporter. In this study, we analyzed molecular FR-alpha and RFC expression in 16 ovarian carcinoma tissues and in 5 ovarian carcinoma cell lines using competitive PCR. Co-expression of the 2 transporters was found both in vivo and in vitro. FR-alpha mRNA expression in the cell lines was in good agreement with the corresponding protein expression evaluated by cellular folic acid binding and immunofluorescence analysis, using a specific monoclonal antibody (MAb) (MOv18). Moreover, RFC mRNA expression levels were consistent with the selective cellular binding of N-hydroxysuccinimide of [3H]-methotrexate (NHS-MTX). The 5 ovarian carcinoma cell lines (IGROV-1, SW-626, SKOV-3, OVCAR-3 and OAW-42), grown at physiological N5-CH3-H4PteGlu concentrations (20 nM) and expressing FR-alpha and RFC levels superimposable to those observed in vivo, were used as in vitro cellular model to evaluate the different contribution of FR-alpha and RFC to the transport of N5-CH3-H4PteGlu. The cytoplasmic N5-CH3-[3H]H4PteGlu accumulation observed in each cell line was approximately linear over 4 hr of incubation, but there was no correlation between the rate of folate internalization and FR-alpha and RFC expression levels. Furthermore, the selective inhibition of FR-alpha and RFC functionality allowed us to distinguish their differential role on the overall N5-CH3-[3H]H4PteGlu intracellular delivery. Treatment with the N-hydroxysuccinimide of folic acid, which blocks FR-alpha activity, showed only a partial inhibition (about 20%) of folate internalization in all the cell lines. In contrast, the inhibition of RFC by NHS-MTX, under conditions that did not affect FR-alpha functionality, generally reduced folate accumulation by more than 70%. Only one cell line (IGROV-1) showed a comparable contribution of the 2 transport systems. Our findings suggest that in ovarian carcinomas, in spite of its over-expression, FR-alpha generally plays a minor role in N5-CH3-H4PteGlu transport compared with RFC.

Biological Transport↗
PubMed1997

Reversal activity of cyclosporin A and its metabolites M1, M17 and M21 in multidrug-resistant cells.

Cyclosporin A (CSA) is an effective inhibitor of the P-glycoprotein (P-gp) activity and has been shown to modulate multidrug resistance (MDR) in in vitro experimental models. During degradation of CSA, the metabolites arising from the parental compound reach high levels in the serum of patients, and it is not clear whether these metabolites maintain the reversal activity of the parental compound, like the metabolites of verapamil. In an in vitro experimental model, we compared the reversal activity of CSA and 3 CSA metabolites (M1, M17, and M21) in the range of concentrations obtained in whole blood during a clinical trial with CSA used as a revertant agent. As experimental model we used LoVo-resistant cells. Our in vitro studies indicated that the metabolic hydroxylation and demethylation of CSA lead to molecules that greatly differ from the parent drug in their reversal activity. In the range of concentration detected in the whole blood of the patients (1-3 microM), CSA had a significant reversal activity. It decreased the IC50 of antineoplastic drugs involved in MDR (vincristine, taxol, doxorubicin and etoposide) but not the IC50 of platinum or methotrexate. CSA increased intracellular doxorubicin content and inhibited P-gp 3[H]azidopine photolabeling. Conversely, CSA metabolite concentrations superimposable to those observed in the patients (0.5-2.2 microM) had no sensitizing effects on the cytotoxicity of MDR-related anti-neoplastic drugs, nor did they affect 3[H]azidopine photolabeling or doxorubicin uptake. This study demonstrates that, during degradation of CSA, metabolite derivatives arise that have a very different reversal activity from that of the parental compound.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Overexpression of folate binding protein in ovarian cancers.

The high affinity folate binding protein (FBP) is overexpressed in ovarian cancers. However, its role in the pathogenesis and biological behaviour of these neoplasms is not clearly understood. Using the monoclonal antibody (MAb) MOv 18 and cytofluorimetric analysis, we investigated FBP expression in frozen neoplastic tissues from 136 patients diagnosed with epithelial ovarian cancer. FBP values were compared with clinico-pathological characteristics (age, stage, histologic grade, histologic type, DNA ploidy, percentage of S-phase cells, and previous chemotherapeutic treatment). Some amount of FBP overexpression was observed in 122 of the 136 tumours examined. The overall mean value of FBP fluorescence index (FBP FI) was 5.6 (median 2.7; min 0.8--max, 78.9). By univariate analysis, FBP FI was overexpressed to a higher degree in ovarian neoplasms with high histologic grade, advanced stage, serous histology, aneuploid status, and high percentage of cells in S-phase. Of the total number (136) of cases, 106 had all the parameters assessed and were thus selected for stepwise selection procedure. The only significant independent variable was the percentage of S-phase cells, which accounted for about 31% of variance of FBP FI. Our results indicate that FBP is associated with parameters of biological aggressiveness in ovarian cancers.

Adenocarcinoma, Mucinous↗
PubMed1997

Homocysteine accumulation in human ovarian carcinoma ascitic/cystic fluids possibly caused by metabolic alteration of the methionine cycle in ovarian carcinoma cells.

The major role of the high-affinity folate-binding protein (FBP) is to regulate cellular folate homeostasis by increasing folate uptake in case of extracellular and intracellular folate deficiency. On this basis, we hypothesised that the overexpression of FBP in ovarian carcinoma might be physiologically associated with folate deficiency in the extracellular fluids, where ovarian carcinoma cells develop in vivo, or it might be the result of a reduced intracellular regeneration of the 5-methyltetrahydrofolate (5-CH3H4 folate). To test these hypotheses, we determined the bioavailability of folate in serum and in ascitic/cystic fluids of ovarian carcinoma patients (n = 36). The intracellular shortage of 5-CH3H4 folate was evaluated in the extracellular fluids by measuring the concentration of homocysteine (Hcy), which is a useful marker of intracellular folate deficiency. Patients with ascites from malignant and benign non-ovarian pathologies were used as controls (n = 30). We found no folate shortage in the serum and ascitic/cystic fluids of ovarian carcinoma patients. The folate concentration was within the normal range and superimposable on that observed in serum and ascites of control patients. However, the ascitic/cystic Hcy concentration was significantly higher (P < 0.005) than the corresponding serum concentration in a large fraction of ovarian carcinoma patients (72%, 26/36), whereas it was higher only in a small fraction of patients with non-ovarian malignant ascites (24%, 4/17), and in no patient with benign ascites. Hcy accumulation in ovarian carcinoma patients was not associated with a defect in the catabolic pathway of Hcy to cysteine, but was consistent with an impaired remethylation process of Hcy to methionine caused by an intracellular shortage of 5-CH3H4 folate. This suggests a possible association between FBP overexpression and a biochemical defect of the cellular folate metabolism involved in the methionine cycle.

Adult↗
PubMed1997

Cyclosporin A as a multidrug-resistant modulator in patients with renal cell carcinoma treated with teniposide.

Patients with refractory metastatic renal cell carcinoma (RCC) were enrolled in a phase II study with teniposide (VM26) and cyclosporin A (CSA) to investigate (1) the effect of CSA on the response rate to VM26; and (2) the effect of CSA on the pharmacokinetics and pharmacodynamics of VM26. Sixteen patients initially received VM26 alone (200 mg m(-2) day(-1) i.v.). No objective responses were observed and all patients crossed over to receive at least an additional two courses (range 2-5) of VM26 plus CSA (5 mg kg(-1) 2h(-1) followed by 30 mg kg(-1) 48h(-1) i.v.). At the end of the 2-h loading dose of CSA, whole-blood CSA levels ranged from 2250 to 3830 ng ml(-1), whereas at the end of the 48-h CSA infusion, CSA ranged from 1830 to 4501 ng ml(-1). CSA significantly (P<0.01) increased the area under the curve (AUC) of VM26. The variation in the paired AUC of VM26 was 50%. Terminal half-life of VM26 was significantly (P<0.01) increased (1.72-fold) after CSA administration, whereas the systemic clearance of VM26 was decreased by 1.4-fold (P<0.01). The nadir neutrophil count after VM26 plus CSA (median 700 microl(-1), range <100 to 2860 microl(-1)) was lower than after VM26 alone (median 1900 microl(-1), range 200 to 6000 microl(-1)). Increased haematological toxicity after CSA could be explained by the increase in the VM26 AUC and by inhibition of P-glycoprotein (P-gp) activity in haematopoietic precursor cells. Bilirubin concentrations in the serum were increased after VM26 plus CSA compared with VM26 alone (P<0.01). Among the 15 patients evaluable for response, one had a minor response, eight had stable disease, and six had progressive disease. In conclusion, the dose of CSA we used achieved plasma concentrations within the effective range for P-gp inhibition. CSA affected both the pharmacokinetics and pharmacodynamics of VM26 in the patients, principally by increasing the plasma concentrations of the antineoplastic drug and VM26 haemopoietic toxicity.

Adult↗
PubMed1997

Non-linear pharmacokinetics of high-dose intravenous verapamil.

AIMS: In an attempt to reverse multidrug resistance, in a recent trial of verapamil in association with doxorubicin, we used escalating doses of continuous intravenous (i.v.) verapamil under close haemodynamic monitoring. We report the pharmacokinetics of escalating doses of verapamil. METHODS: We studied nine patients [seven males, two females; median age 46 years (range, 31-57)] with advanced adenocarcinoma of the colon and normal renal, hepatic, and cardiac functions. After a loading dose (0.15 mg kg-1 followed by 12 h continuous i.v. infusion at 0.20 mg kg-1 h-1), the infusion rate (ko) of verapamil was increased every 24 h (0.25, 0.30, 0.35, and 0.40 mg kg-1 h-1). The highest rate was maintained for 48 h. Doxorubicin was given as a continuous i.v. infusion from 12 to 108 h (n = 4) or 60 to 108 h (n = 5). Blood samples and urine collections were taken every 12 h. Verapamil and nor-verapamil were assayed by high performance liquid chromatography. We calculated systemic clearance of verapamil (CL = ko/Css) and renal clearance (CLr) of verapamil and nor-verapamil. The Css vs rate relationship was fitted to a Michaelis-Menten equation: Css = ko. (K(m)+Css)/(V.Vm). RESULTS: CL was dose-dependent and in all nine patients a significant reduction in CL was observed over the dose range (mean CL +/- s.d. were 0.51 +/- 0.31, 0.38 +/- 0.16, 0.32 +/- 0.18, and 0.27 +/- 0.11 l h-1 kg-1, respectively, at 0.25, 0.30, 0.35, and 0.40 mg kg-1 h-1; P = 0.0001). Css increased more than proportionally to the dose rate and the Css vs rate relationship was best defined by a Michaelis-Menten equation (K(m) = 730 micrograms l-1; V.Vm = 0.55 mg kg-1 h-1), (r = 0.994; P = 0.006). CLr of verapamil and nor-verapamil was not saturable but the contribution to the elimination was only 2 to 4% of the dose. CONCLUSIONS: These findings suggest a non-linear, capacity-limited metabolic clearance of high-dose verapamil. Using escalating infusion rates, high verapamil concentrations (1500-2500 ng ml-1) were achieved without major toxicity. Saturable clearance may cause higher bioavailability and slower elimination of verapamil after acute oral overdoses.

Adenocarcinoma↗
PubMed1997

Pulsatile ocular blood flow variations with axial length and refractive error.

Ocular pulse amplitude (PA) and pulsatile ocular blood flow (POBF) were studied in 80 eyes from 80 subjects with a refractive error between +3.00 and -28.00 dpt using the Langham Ocular Blood Flow System. PA and POBF were correlated with axial length and refractive error using linear regression analysis. A significant correlation (p < 0.001) was found between PA and axial length (r = -0.787), PA and refractive error (r = 0.775), POBF and axial length (r = -0.655) and POBF and refractive error (r = 0.650). Myopic eyes were further divided into subgroups according to axial length, refractive error and fundus oculi characteristics. Each subgroup exhibited a significant reduction in PA (p < 0.001) compared to the control group. POBF reduction was significant in every subgroup except the subgroup with a refractive error lower than 6 dpt and the subgroup with an axial length shorter than 26 mm.

Adult↗
PubMed1996

Determination of unbound etoposide concentration in ultrafiltered plasma by high-performance liquid chromatography with fluorimetric detection.

Etoposide is a highly protein bound drug, and monitoring the concentration of free drug could help individualize dosage in oncological patients. The cost and difficulty of the standard techniques (equilibration dialysis) has hampered the monitoring of free drugs. We describe a simple HPLC method for the measurement of free etoposide concentration in plasma. Sample preparation involves the ultrafiltration of plasma by a Centrifree device for 30 min at 2000 g and extraction with chloroform. The isocratic separation is performed with a mu Bondapak phenyl analytical column. Fluorimetric detection is used (288-328 nm excitation and emission wavelengths). Linearity of the calibration curve is excellent between 0.05 and 1 microgram/ml. Accuracy and precision are reported at the concentrations 0.06 and 0.4 microgram/ml: within-run accuracy is 10% and 6.2%, respectively; between-run accuracy is < or = 1%; within-run coefficients of variation (C.V.) are 10.6 and 5.0%; between-run C.V. are 11.6 and 6.8% respectively. The range of the assay is 0.05 to 1 microgram/ml. The feasibility of the technique has been tested in 7 patients treated with oral etoposide for hepatocarcinoma (mean protein binding 91%). We found no interference from endogenous substances, co-administered drugs (alizapride, furosemide, ranitidine) and other antineoplastic agents (doxorubicine, idarubicine, vinblastine, vinorelbine).

Aged↗
PubMed1996

Cellular pharmacology of idarubicinol in multidrug-resistant LoVo cell lines.

Idarubicin (IDA) is a daunorubicin (DAU) analog that is being used to treat a variety of human malignancies. The major circulating metabolite of IDA is idarubicinol (IDOL). After administration of IDA to patients, the systemic exposure to IDOL is greater than IDA. We investigated the cytotoxic effect of IDOL in the LoVo human colon-carcinoma cell line and its derivative multidrug-resistant (MDR) sub-lines. In LoVo-sensitive cells, the extracellular IDOL concentration inhibiting cell growth by 50% (IC50) was about 2-fold higher than IDA IC50 but lower than DAU IC50. After continuous exposure of the LoVo parental cells to 20 nM IDOL, 5 drug-resistant clones were obtained. All these clones exhibited an MDR phenotype, indicating that IDOL is involved in multidrug resistance. The resistance index (RI) to IDOL was investigated in LoVo MDR sub-lines obtained by IDOL (LoVo-IDOL-1), IDA (LoVo-IDA-1) and DOX (LoVo-DOX-1) selection. In spite of the drug used for their selection, all the MDR sub-lines exhibited an RI to IDOL lower than DAU and only 2-fold higher than IDA. In LoVo-IDOL-1 cells the RI was 5, 11 and 32 for IDA, IDOL and DAU respectively. Differences in the RI were explained by the greater intracellular tolerance exhibited by MDR cells to DAU than to IDOL and IDA. In the LoVo-IDOL-1 sub-line, the intracellular drug concentration inhibiting cell growth by 50% (IC50int) was higher than in the sensitive cells by 11.4-, 4.7- and 2.8-fold for DAU, IDOL, and IDA respectively. Differences in the intracellular tolerance were explained by the different intracellular distribution of DAU compared with IDOL and IDA. While DAU had a higher nuclear location in LoVo-sensitive cells than in resistant cells, IDOL and IDA maintained the same distribution both in sensitive and in resistant cells. In conclusion, contrary to what has been observed for other derivative metabolites of anthracyclines, the metabolism of IDA to IDOL must not be considered an inactivation pathway. IDOL is a potent inhibitor of cell growth and retains good activity in MDR cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Inhibition of Pgp activity and cell cycle-dependent chemosensitivity to doxorubicin in the multidrug-resistant LoVo human colon cancer cell line.

To determine whether the cell cycle affects multidrug resistance (MDR) and its reversal, doxorubicin (DOX) cytotoxicity and the effect of inhibition of P-glycoprotein (Pgp) activity by verapamil (VER) were investigated in MDR LoVo cell lines (LoVo-R) in different phases of the cell cycle. Synchronised cells were obtained by exposing cells for 24 h to non-toxic concentrations (40 nmol/l) of methotrexate (MTX), which induced a reversible blockade in the S phase. DOX cytotoxicity was higher if cells were exposed to DOX shortly after the pretreatment with MTX, when most cells were in the S phase of the cell cycle. At that time, the DOX concentration inhibiting cell growth by 50% (IC10) was decreased by approximately 4-fold compared to non-synchronised cycling cells. DOX cytotoxicity remained high during the transition from the S to the G2M phase, but was reduced when the cells had shifted to the G2M phase. Inhibition of Pgp activity by VER (6 mumol/l) enhanced DOX uptake and resulted in an intracellular nuclear compartmentalisation of DOX in LoVo-R cells. These effects were not significantly different (P = NS) in the different phases of the cell cycle. However, similar increases in intracellular DOX uptake due to the inhibitory effect of VER on Pgp greatly potentiated DOX cytotoxicity in LoVo-R cells synchronised in the S or G2M phase compared with non-synchronised cycling cells. The ratio between DOX IC50 in the absence and presence of VER in LoVo-R cells synchronised in the S phase and in cycling cells was 11.1 and 4.1, respectively (P < 0.01). This greater potentiation could be explained by the increased chemosensitivity of the S- and G2M-phase cells to intracellular DOX concentration compared with the non-synchronised cells. Finally, the combination of synchronisation by MTX and of inhibition of Pgp activity by VER produced a considerable reduction in DOX IC50 (approximately 50-fold) in LoVo-R cells compared with the cells not treated with MTX and VER. In conclusion, this study demonstrates that, in LoVo-R cells, the effect of Pgp inhibition on DOX cytotoxicity is dependent on cell cycle phase. DOX cytotoxicity is maximal when inhibition of Pgp activity occurs during the S/G2M phases.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Age-related ocular blood flow changes.

PURPOSE: Pulsatile ocular blood flow (POBF is influenced by well-known parameters, such as intraocular pressure (IOP), heart rate, scleral rigidity, blood pressure, and posture. Age is also likely to influence POBF strongly. The purpose of this study was to evaluate POBF in relation to age in normal subjects. METHODS: Relevant data were collected from a sample of 105 normal subjects, ranging in age from 10 to 80 years. To measure the effect of age on POBF, the subjects were divided into seven groups of 15 subjects each; the age range of each group spanned one decade, beginning with age 10. POBF and pulse amplitude (PA) were measured in sitting and supine positions and after suction cup application. RESULTS: Using linear regression analysis, there was a significant correlation between PA and age in the supine position (P = 0.012) and after suction cup application (P = 0.002); in the sitting position, there was a borderline level of statistical significance (P = 0.053). In the sitting position, POBF was 819 +/- 212 microliters/minute in the second decade and 630 +/- 194 microliters/minute in the eighth decade. In the sitting position and after suction cup application, but not in the supine position, a statistically significant correlation between POBF decrease and age was found with linear regression analysis (P < 0.001 and P = 0.004, respectively). Using multiple regression analysis, POBF values revealed a significant correlation with age (P < 0.001), but not with systolic and diastolic brachial pressure. Considering all the subjects, analysis of variance for repeated measures highlighted a significant decrease of POBF from the sitting to the supine position and associated with an IOP increase (P < 0.001) without significant changes of PA. After suction cup application, there was a significant reduction of both PA and POBF (P < 0.001). CONCLUSIONS: The data revealed that as age increased, PA decreased in all three series of measurements. POBF decreased with age, and in subjects older than 50 years, the decrease was more evident. These findings are especially noticeable after IOP increase with suction cup. It must be considered that the age-related value of POBF is a fundamental parameter to evaluate correctly the hemodynamic aspects of the pathologies affecting the eye.

Adolescent↗
PubMed1995

Structure-activity relationship of verapamil analogs and reversal of multidrug resistance.

We studied the relationship between the chemical structure and multidrug resistance (MDR) reversal activity of racemic verapamil (VER) and 14 VER analogs (VAs). The LoVo-R human colon carcinoma cell line was used as an experimental model. This cell line exhibited a typical MDR phenotype and overexpressed the MDR1 gene products. Key structural features were identified as being related to MDR reversal and cytotoxic activity. In particular, we demonstrated that the methoxy groups in the VER molecule structure [1.7-Bis-(3.4-dimethoxyphenyl)-3-methylaza-7-cyan-8-methyl-n onane] prevented cytotoxicity when the VAs were used alone, whereas the 7-cyan-8-methyl groups were important for MDR reversal activity and interaction with P-glycoprotein (P-gp). Among the VAs tested, the most active compounds were gallopamil, R-isomer of VER (R-VER), and nor-VER, which potentiated doxorubicin (DOX) cytotoxicity by 52.3 +/- 7.2 (n = 3 +/- SD), 38.9 +/- 6.4 (n = 4 +/- SD), and 35.4 +/- 4.3 (n = 3 +/- SD) times, respectively. The reversal activity of these compounds was similar to that of VER, which enhanced DOX cytotoxicity by 41.3 +/- 5.0 (n = 3 +/- SD) times. The potentiation of DOX cytotoxicity was associated with an increase in DOX uptake in LoVo-R cells and with an increased [3H]azidopine P-gp photolabeling inhibition. Some compounds that had a high reversal potency (i.e. R-VER and nor-VER) showed a lower calcium antagonist activity than VER, and seem useful candidates for the treatment of MDR in cancer patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Pharmacokinetics of doxorubicin co-administered with high-dose verapamil.

The potential for the modification of the pharmacokinetics of doxorubicin (DOX) concurrently administered with high-dose verapamil (VER) has been investigated in 17 patients with advanced neoplasms refractory to drugs belonging to the multidrug resistance spectrum. Steady-state concentration of DOX, systemic clearance and urinary excretion were analysed. No significant difference was found between the kinetic parameters estimated for DOX at different levels of VER and those reported for doxorubicin as single agent. It can be concluded that VER does not appear to modify DOX kinetics.

Adult↗
PubMed1995

Effect of cyclosporine on teniposide pharmacokinetics and pharmacodynamics in patients with renal cell cancer.

Five patients with metastatic renal cell cancer (RCC) entered this study. The patients received two courses of teniposide (VM26) (200 mg/m2/24 h i.v.) after which no objective response was observed: three patients had stable disease (SD) and two had progressive disease. Cyclosporine (CsA) (5 mg/kg/2 h followed by 30 mg/kg/48 h i.v.) was then added (VM26/CsA) and at least another two courses were administered. Pharmacokinetic and pharmacodynamic parameters were analyzed. CsA increased the area under curve (AUC) of VM26 in four out of five patients; on average, the variation in the paired AUC of VM26 was 41%. Nadir granulocyte count was lower (average 650/mm3, ranging from < 100 to 1800/mm3) after VM26/CsA than after VM26 (average 1260/mm3, ranging from 200 to 2100/mm3) (p < 0.01). Bilirubin concentration in the serum was increased after VM26/CsA compared with VM26 (p < 0.05). Finally, after two courses of VM26/CsA, four patients had stable disease and one patient had a minor response. In conclusion, the ongoing pilot study indicates that CsA affects both the pharmacokinetics and the pharmacodynamics of VM26.

Aged↗
PubMed1995

DNA flow cytometric evaluation of cell cycle distribution in ulcerative colitis: a proposed method for assessing severity of disease.

The assessment of disease severity in ulcerative colitis depends mainly on subjective variables, and an objective method of assessing mucosal inflammation is needed. Determination of the synthetic phase of the cell cycle is an accurate expression of inflammatory activity in the colonic mucosa. The aim of the study was to find out if the proliferative index or the synthetic phase (S phase) of the colonic mucosa of patients with ulcerative colitis, as evaluated by DNA flow cytometry, is a reliable and reproducible marker of disease activity. Sixty consecutive patients with ulcerative colitis of different degrees of activity were entered into the study and submitted to colonoscopy plus multiple rectal biopsies. Disease severity was defined for each patient by means of a clinical, endoscopic, and histological score. Flow cytometry was used to calculate the proliferative index and the S phase of the cell cycle. A statistically significant correlation (p < 0.001) was found between all indices of severity. It is suggested that flow cytometric evaluation of the cell cycle in the rectal mucosa may be an efficient method of assessing severity of disease and efficacy of medical treatment in ulcerative colitis.

Adult↗
PubMed1995

Brief report: prognostic importance of cellular DNA content in T1-2 N0 laryngeal squamous cell carcinomas treated with radiotherapy.

One hundred fifty-two unselected, consecutive patients with T1-2N0 laryngeal squamous cell carcinoma received radical radiation therapy at the Division of Radiotherapy, Centro di Riferimento Oncologico, Aviano, Italy. Thirty-one (20.4%) of the patients showed disease recurrence or persistence (R/P) after radiotherapy. Flow-cytometric DNA ploidy measurements were performed in 72 cases; 20 had tumor R/P and 52 did not. Tumor R/P occurred more frequently (in 17 [85%] of 20 cases) in patients with diploid tumors. The hazard ratio of recurrence in diploid tumors as compared with aneuploid tumors, after inclusion of all the other significant prognostic factors in a Cox proportional hazards model, was 8.9 (P < .01). Therefore DNA ploidy seems to be an important marker of tumor R/P in patients with T1-2N0 laryngeal carcinoma after radiotherapy.

Carcinoma, Squamous Cell↗
PubMed1994

Comparison of mechanisms responsible for resistance to idarubicin and daunorubicin in multidrug resistant LoVo cell lines.

Two human colon carcinoma drug resistant clones (LoVo-IDA-1 and LoVo-IDA-2) were selected by continuous pressure of LoVo parent cell lines to idarubicin (IDA). Both cell sublines exhibited a typical multidrug resistance (MDR) phenotype but, despite IDA selection, the resistance index (RIext) was higher for daunorubicin (DAU) (RIext = 101-112) than for IDA (RIext = 20-23). A similar pattern of cross-resistance was also observed in two (DOX) doxorubicin-selected LoVo cell lines (LoVo-DOX-1 and LoVo-DOX-2). All the MDR cell lines exhibited decreased drug accumulation and increased intracellular drug tolerance as evidenced by the greater intracellular amount of drug required to cause a 50% growth inhibition (IC50int) compared to their parent cell line. The differences between DAU and IDA RIext exhibited by MDR cells were a function of intracellular resistance. DAU IC50int was 13.9 and 14.9 times higher in LoVo-IDA-1,2 and 6.4 and 6.2 in LoVo-DOX-1,2 cell lines, respectively, than in LoVo-sensitive cells, whereas IDA IC50int was only 3.6 and 3.2 times higher in LoVo-IDA-1,2 and 2.2 and 2.3 in LoVo-DOX-1,2 cell lines, respectively. Conversely, variations in IDA accumulation between resistant and sensitive cells were similar to those observed for DAU [the ratios between DAU uptake in sensitive and resistant cells were almost identical (P = NS) to those observed for IDA]. Differences between IDA and DAU intracellular distribution accounted for the relatively higher DAU intracellular resistance. In fact nuclear/cytoplasmic (N/C) DAU fluorescence ratio was higher (P < 0.01) in sensitive (N/C = 3.4 +/- 2.7) than in MDR cells (N/C ranging from 0.31 +/- 0.2 to 0.41 +/- 0.1). In contrast, no significant (P = NS) differences were observed in IDA N/C ratios between sensitive and MDR cells (N/C ranging from 0.16 +/- 0.1 to 0.20 +/- 0.1). In MDR cells, 1-hr VER (10 microM) treatment partially reverted both DAU N/C ratios and intracellular DAU resistance but neither changes in IDA N/C ratios nor variation in intracellular IDA resistance were observed following VER exposure. In conclusion, the greater intracellular drug tolerance that MDR cells show for DAU compared to IDA makes IDA more effective than DAU in MDR cells overexpressing P-glycoprotein (P-gp).

ATP Binding Cassette Transporter, Subfamily B, Mem↗