Synergistic Effects of Valproic Acid and Mitomycin C in Adenocarcinoma Cell Lines and Fresh Tumor Cells of Patients with Colon Cancer

Valproic acid has been demonstrated to mediate cytotoxic effects against tumor cells by acting as a histone-deacetylase inhibitor. However, to date, there are only limited data on the effects of valproic acid in colon cancer. Moreover, information regarding combinations of the drug with chemotherapeutic agents is very limited. The latter is of interest as there is increasing evidence for synergism between so-called "molecular targeting drugs" and chemotherapy. We first demonstrated that valproic acid dose-dependently reduced the viability of adenocarcimona cell lines. After co-incubation with a variety of chemotherapeutic agents, only valproic acid in combination with mitomycin C consistently induced synergistic growth inhibition in all cell lines. To confirm these results in an ex vivo situation, five samples of fresh colon cancer cells were studied. Again, the effect of valproic acid on the viability of the fresh tumor cells was dose dependent. In four of five samples of freshly isolated colon cancer cells, the synergistic effect of valproic acid and mitomycin C on the inhibition of cell growth was confirmed by calculation of the combination index by multiple drug effect analysis. In conclusion, this is the first demonstration that valproic acid as a model substance for histone-deacetylase inhibitors is effective in tumor cells freshly isolated from patients with colon cancer and that the combination of mitomycin C and valproic acid synergistically decreases viability of colon cancer cells.

Inhibition of osteosarcoma cell proliferation by the Hedgehog-inhibitor cyclopamine

Osteosarcomas (OS) are the most frequent primary malignant bone tumors in humans. Even though OS are chemosensitive, about 30% of patients must be considered poor responders and consequently have a dismal long term prognosis. The Hedgehog (Hh) gene is crucial in the signalling pathways of proliferation and differentiation during embryonic development. There is evidence that uncontrolled activation of this pathway results in specific types of cancer and that inhibition of Hh signalling is able to suppress tumour growth and to induce apoptosis of neoplastic cells. This study investigates the impact of the steroidal alkaloid and Hh-inhibitor cyclopamine on osteosarcoma cells. Thus we demonstrate the drug's impact on cellular proliferation, cell cycle cell death as well as the cells' metabolism. We here demonstrate that cyclopamine exhibits a high efficacy against the osteosarcoma cell lines HOS, SaOS and OS-KA, a self-established primary osteosarcoma cell line. In particular, cyclopamine is able to inhibit proliferation and to promote cell death. Our results provide evidence for the potency of the Hh-inhibitor cyclopamine as a future treatment of osteosarcomas.

Highly active antiretroviral therapy (HAART) improves survival in HIV-associated Hodgkin's disease: results of a multicenter study

BACKGROUND

The purpose of the study was to evaluate the outcome of Hodgkin's disease (HD) in patients infected with the human immunodeficiency virus (HIV) with respect to the use of highly active antiretroviral therapy (HAART).

MATERIALS AND METHODS

This cohort study included patients with HIV-HD diagnosed from June 1984 to February 2004. Patients treated in the pre-HAART era (1984-1996) were compared with those belonging to the HAART era (1997-2004).

RESULTS

Of 66 patients with HIV-HD, 47 (71%) presented with stage III/IV disease and 38 patients (58%) with an AIDS-defining illness. Fifty-nine of 66 patients (89.4%) underwent curative intended chemotherapy. Patients receiving HAART (n = 34) had a significantly better 2-year overall survival (OS) than those not receiving HAART (74% versus 30%, P <0.001). The 2-year OS of HAART-responders was 88% compared with 19% in patients without HAART-response (P = 0.0002). By multivariate analysis patients without HAART had a 5.6-fold higher risk for 3-year mortality [HR 5.6, 95% confidence interval (CI) 2.20-14.26]. Three-year mortality was significantly higher in patients without complete remission (HR 4.40, CI 1.77-10.99), with stage III/IV HD (HR 4.64, CI 1.31-16.49) and with CD4 cells <200/microl (HR 2.69, CI 0.99-7.33).

CONCLUSIONS

Use of HAART significantly improved the overall survival in patients with HIV-HD.

Deregulated expression of prostate apoptosis response gene-4 in less differentiated lymphocytes and inverse expressional patterns of par-4 and bcl-2 in acute lymphocytic leukemia

INTRODUCTION

Prostate apoptosis response gene-4, known as par-4, is a new proapoptotic factor functionally required but not sufficient for apoptosis. Since there is evidence from prostate cancer cells that par-4 is involved in regulation of bcl-2 we assessed expression of par-4 and bcl-2 in different populations of normal and neoplastic lymphocytes.

MATERIALS AND METHODS

Expression of par-4 mRNA and protein in different subpopulations of normal and neoplastic lymphocytes was assessed by reverse transcription polymerase chain reaction and Western blot.

RESULTS

Par-4 mRNA was not detectable in lymphocytes of healthy volunteers (n = 10), but was present in the majority of samples of chronic lymphocytic leukemia (n = 30), chronic lymphocytic leukemia/prolymphocytic leukemia (n = 6) and acute lymphocytic leukemia (n = 10). Par-4 protein was expressed unanimously in samples of mononuclear cells from healthy volunteers and patients with CLL, but less frequently in immature lymphocytes, including neoplastic cells of CLL/PLL and ALL. The decreased frequency of par-4 expression in immature subpopulations was confirmed by results on lymphocytic cell lines at various stages of maturation. Comparing the expressional patterns of par-4 and bcl-2 there was an inverse relationship of both proteins in ALL and different lymphocytic cell lines, indicating a functional relationship of par-4 and bcl-2.

CONCLUSIONS

This study establishes par-4 as a factor expressed in the majority of normal and neoplastic lymphocytic cells, demonstrating a decreased frequency of protein expression in less differentiated lymphocytes and an inverse expressional pattern of par-4 and bcl-2 in lymphocytic cell lines and ALL.

Antioxidative treatment prevents activation of death-receptor- and mitochondrion-dependent apoptosis in the hearts of diabetic rats

AIMS/HYPOTHESIS

The mechanisms by which glucose injures cells of the cardiovascular system include generation of reactive oxygen species and induction of cellular apoptosis. To date, little is known about the molecular events of hyperglycaemia-induced apoptosis in the heart in vivo.

METHODS

Male Sprague-Dawley rats were rendered diabetic by a single intraperitoneal injection of 60 mg/kg body weight streptozotocin. Caspase activities in cardiac ventricular tissue were determined using fluorometric and immunoassay caspase-activity assay kits respectively. Expression levels of proteins of the apoptotic cascade were determined with western blot analyses using specific antibodies.

RESULTS

Four weeks of hyperglycaemia induced significant apoptosis in cardiac tissue. Determining the initiators of death-receptor-dependent apoptosis revealed induction of CD95/Fas and caspase-8. Examination of the activities of effector caspases revealed increased activity of caspase-6, but not caspase-3 and -7. On evaluating inhibitors of apoptosis, we found up-regulation of caspase-3 and -7-inhibiting X-linked inhibitors of apoptosis in diabetic rats. Hyperglycaemia also induced significant mitochondrion-dependent apoptosis. Our evaluation of expression levels of Bcl-2 family members showed increased expression of pro-apoptotic Bak and Bax in diabetic rats. Antioxidative treatment with lipoic acid significantly suppressed apoptosis and down-regulated caspase-6, -8 and -9 activity, as well as expression levels of pro-apoptotic Bcl-2 proteins without changing blood glucose levels.

CONCLUSIONS/INTERPRETATION

The present study indicates that reactive oxygen species induced by high glucose are involved in both death-receptor- and mitochondrion-dependent apoptosis in the heart in vivo. It also suggests that antioxidants may be a therapeutic option for preventing cardiovascular damage in diabetes mellitus in humans.

Reduced-dose cladribine (2-CdA) plus mitoxantrone is effective in the treatment of mantle-cell and low-grade non-Hodgkin's lymphoma

Cladribine (2-chlorodeoxyadenosine) (2-CdA) has been shown to be effective in mantle-cell (MCL) and low-grade lymphomas (lgNHL). The aim of this multicentre study was to evaluate the rate and duration of remissions and to examine the toxicity of the combination of reduced-dose 2-CdA and mitoxantrone (CdM) in MCL and lgNHL as first-line therapy or for patients in their relapse. A total of 285 courses, median of five courses per patient, were administered to 62 evaluable patients (42 previously untreated, 20 relapsed) with 5 mg/m(2) 2-CdA per day given as an intermittent 2-h infusion over 3 consecutive days combined with 8 mg/m(2) mitoxantrone on days 1 and 2 for the untreated patients or 12 mg/m(2) mitoxantrone on day 1 for patients in their first relapse for a maximum of six cycles every four weeks. 32 follicular, 18 MCL, 9 lymphoplasmacytoid, 2 marginal zone and 1 unclassified low-grade B-cell lymphoma were involved in the study. 56 of the 62 patients responded to CdM resulting in an overall response rate of 90% (95% confidence interval (CI), 80-96%) with a complete remission (CR) rate of 44% (95% CI, 31-57%) and a median duration of remission of 25 months (range 6-42+). The overall survival rate at 48 months was 80%. For 42 previously untreated patients, the overall response rate was 88% (95% CI, 74-96%) with a CR rate of 38% (95% CI, 24-54%), whereas the response rate for the group of 20 previously treated patients was similar with a 95% overall response (95% CI, 75-100%) and a CR rate of 55% (95% CI, 32-77%). In MCL, CdM showed a high activity, achieving a response rate of 100% (95% CI, 81-100%) with a CR rate of 44% and a median duration of remission of 24 months (range 6-35+). Myelosuppression was the major toxicity with 23% grade 3 granulocytopenia and 50% grade 4. Thrombocytopenia was less commonly observed, with only 8% grades 3 and 4. These results demonstrate that the combination of reduced-dose 2-CdA and mitoxantrone is a highly active regimen in the treatment of low-grade lymphomas, and in particular of MCL.

In vitro induction of apoptosis of neoplastic cells in low-grade non-Hodgkin's lymphomas using combinations of established cytotoxic drugs with bendamustine

BACKGROUND AND OBJECTIVES

Regulation of apoptotic cell death is being increasingly recognized as a mechanisms by which cytostatic agents mediate tumor cell death. Preliminary clinical studies with bendamustine, an alkylating agent with a purine nucleus, provide strong evidence that this drug is a highly effective cytostatic in low grade lymphomas. Therefore, we investigated the in vitro activity of bendamustine in combination with other established cytotoxic drugs.

DESIGN AND METHODS

2 lines (DOHH-2, WSU-NHL) and mononuclear cells (MNC) from patients with leukemic low-grade B-non-Hodgkin's lymphoma (NHL) (n=10), T-NHL (n=7) and chronic lymphocytic leukemia (CLL) (n=12). Apoptosis (7-AAD), depolarization of mitochondrial membrane potential (MMP, JC-1), caspase-3-activity (FIENA) and cell proliferation (XTT/WST-1) were determined. Several incubation times and drug dosages (for IC(30/50/75/90)) were studied. Synergistic, additive or antagonistic effects were calculated by a median plot effect and the combination index (CI) method.

RESULTS

In general, combinations of bendamustine with mitoxantrone or doxorubicin resulted in antagonistic effects in the tested cell lines and the MNC from the patients. CI-calculation failed in these cases since there was not a sufficient dose response. On the other hand, the combination of bendamustine with 2-CdA showed synergistic in vitro activity on the tested cell lines, neoplastic lymphocytes from patients with peripheral T-cell lymphomas and partially on MNC from patients with CLL and B-NHL. The antagonism of the combination of bendamustine and anthracyclines appeared to be due to inhibition of depolarization of mitochondrial-membrane potential and caspase-3-activity during apoptosis of the studied cell lines.

INTERPRETATION AND CONCLUSIONS

In conclusion, our results suggest that schedules using combinations of bendamustine and anthracyclines should not be recommended for the treatment of low-grade NHL, whereas bendamustine combined with 2-CdA could be considered for the development of future treatment strategies.

Treatment of aggressive, or progressing indolent peripheral T- and NK-cell neoplasias by combination of fludarabine, cyclophosphamide and doxorubicine

BACKGROUND

Regarding standardization of treatment, classification, and pathophysiology of peripheral T- and NK-cell neoplasias the current knowledge is markedly behind that of B-cell lymphomas, which are approximately 10 times more frequent. In May 2000, the study group 'Peripheral T- and NK-cell Neoplasias' was founded in Frankfurt/M. This group decided on a clinical protocol and a scientific program for research on the pathophysiology of these entities. Rationales for the therapeutic regimen are the efficacy of cyclophosphamide and doxorubicine as shown in protocols for treatment of high grade lymphoma, the synergism of cyclophosphamide and fludarabine, and reports demonstrating the efficacy of fludarabine in T-cell neoplasias.

PATIENTS AND METHODS

Patients will be treated with a combination of fludarabine (30 mg/m(2) days 1-3), cyclophosphamide (1000 mg/m(2) day 1) doxorubicine (25 mg/m(2) day 2+3) (FCD). For patients > or =65 years a dose-reduced FCD regimen will be administered. In patients included in the treatment study and additionally in patients with indolent disease not requiring therapy, scientific projects on the biology of peripheral T- and NK-cell neoplasias will be performed.

CONCLUSIONS

Expected conclusions of the projected study are the establishment of treatment and diagnostic standards, and improvement of classification of these entities by clinical, morphologic and biologic parameters.

Changing incidence and survival in patients with aids-related non-Hodgkin's lymphomas in the era of highly active antiretroviral therapy (HAART)

To determine role of highly active antiretroviral therapy (HAART) and additional factors in incidence and outcome of patients with AIDS-related non-Hodgkin's lymphomas (NHL) we retrospectively analyzed 257 cases of AIDS-related NHL (24 low-grade, 168 high-grade B-cell, 6 high-grade T-cell, and 59 primary CNS lymphomas (PCNSL) among 2004 patients with HIV-infection treated at the University Hospital of Frankfurt, Germany from January 1983 to May 1999. Data were evaluated by univariate and multivariate analyses, using overall survival as end point. Patients received CHOP-like therapy as standard treatment. Until May 1999 incidence of all diagnosed cases of NHL was decreasing (1991-94: 14.2% versus 1995-5/99: 12.8%). Mainly, the incidence of low-grade NHL and PCNSL clearly decreased whereas the incidence of high-grade B-cell NHL increased compared to all diagnosed cases of NHL (1983-86: 53.3% versus 1995-5/99: 78.6%). One-year survival probability of all screened patients with AIDS related NHL was 54%, while 5-year survival rate remained 5%. We found age <25 years, development of NHL in the years before 1990, IVDU, CD4 counts <150/microl, PCNSL as well as NHL as the AIDS index disease, to be highly significant independent predictors of poor survival, including increased hazard ratios. In the era of HAART incidence of NHL is decreasing, mainly the incidence of low-grade NHL and PCNSL. Overall survival of patients has been prolonged with HAART. This development is mainly due to improvement of antiretroviral therapy, rather than to any fundamental changes in the chemotherapeutic treatment of NHL. Therefore, new treatment approaches for AIDS-related NHL should focus on more efficient antiretroviral therapy in association with combination chemotherapy.

T-large granular lymphocyte leukaemia with natural killer cell-like cytotoxicity and expression of two different alpha- and beta-T-cell receptor chains

We describe a case of cytotoxic T-large granular lymphocyte leukaemia showing typical morphological features, expressing antigens characteristic for cytotoxic T cells and exhibiting marked natural killer-like cytotoxicity towards different target cells. Moreover, characterization of the T-cell receptors revealed simultaneous expression of two different types of beta-chains as well as alpha-chains by the malignant cell clone. The patient had an 8 year history of indolent disease, before progressing to an aggressive clinical course hardly responsive to chemotherapeutic treatment. This is the first description of a peripheral T-cell neoplasm expressing four distinct types of T-cell receptor molecules.

Induction of apoptosis using 2',2' difluorodeoxycytidine (gemcitabine) in combination with antimetabolites or anthracyclines on malignant lymphatic and myeloid cells. Antagonism or synergism depends on incubation schedule and origin of neoplastic cells

Induction of apoptosis in vitro using gemcitabine (dFdC) in combination with cladribine (2-CdA) and other cytotoxic drugs on malignant mononuclear cells (MNCs) of patients with acute myeloid leukemia (AML, n=20) and chronic lymphocytic leukemia (CLL, n =20) in myeloid (HL60, HEL) and lymphatic cell lines (HUT78, JURKAT) was investigated using different incubation conditions (simultaneous and consecutive). Furthermore, the influence of dFdC on the level of intracellular metabolites of 2-CdA was studied using high-performance liquid chromatography (HPLC). Apoptosis was evaluated using flow cytometry with 7-aminoactinomycin D. In MNCs of patients with CLL, dFdC + 2-CdA showed an antagonistic effect when applied simultaneously. This antagonism was reduced by consecutive application. The combination of dFdC with doxorubicin was synergistic, independent of incubation schedule. In blasts from newly diagnosed patients with de novo AML, all drug combinations (dFdC+2-CdA, doxorubicin, or cytosine arabinoside) were antagonistic by simultaneous incubation. Reduced antagonism or even synergism was shown (P<0.001) by consecutive incubation. The simultaneous combination of dFdC with 2-CdA in all tested cell lines resulted in a competitive inhibition on the rate of apoptosis. By changing the incubation period to a consecutive schedule, the antagonism was diminished or synergism of apoptosis was measured (P< 0.001). Using similar incubation conditions, these experiments were supported by HPLC measurement of intracellular metabolites of 2-CdA influenced by dFdC application. In conclusion, we demonstrated that the efficacy of dFdC in vitro in combination with other cytotoxic drugs depends on the incubation condition and on the origin of neoplastic cells (lymphatic vs myeloid). The data suggest that simultaneous combination therapy with purine and pyrimidine analogues may not improve the clinical efficacy of one or the other drug administered alone.

Induction of apoptosis by 2-chloro-2'deoxyadenosine (2-CdA) alone and in combination with other cytotoxic drugs: synergistic effects on normal and neoplastic lymphocytes by addition of doxorubicin and mitoxantrone

2-CdA is active as a single agent in the treatment of low-grade lymphomas. We analyzed the induction of apoptosis by 2-CdA alone (n=5) and in combination with other drugs in peripheral lymphocytes from 25 patients with leukemic low-grade lymphomas and from 25 healthy volunteers. 2-CdA was tested in 4 escalating concentrations (0.05 microg/ml to 0.4 microg/ml). Linear regressions showed a dose dependent apoptosis rate of 0.29 x microg 2-CdA/ml + 0.11 (r2=0.88, p=0.006) in normal cells and 0.41 x microg 2-CdA/ml + 0.15 (r2=0.88, p=0.005) in leukemic cells. Intracellular metabolization of 2-CdA into 2-CdA-5'mono-, -di- and the active metabolite -triphosphate was analyzed by HPLC and paralleled the dose dependent increase of apoptosis. The combination of 2-CdA with doxorubicin or mitoxantrone had a synergistic effect on the induction of apoptosis (p<0.001) in both normal and neoplastic lymphocytes, whereas 2-CdA plus etoposide or cytosine arabinoside were only additive. Due to the flat slope of the dose response of 2-CdA concentration on apoptosis we assume that higher in vivo dosages of 2-CdA in the treatment of low-grade lymphomas may not result in a higher clinical efficacy. The synergistic lymphocytotoxic effect of 2-CdA combined with doxorubicin or mitoxantrone may be relevant for new treatment approaches.

Intermittent 2-hour-infusion of cladribine as first-line therapy or in first relapse of progressive advanced low-grade and mantle cell lymphomas

Aim of this multicenter-study was to evaluate rate and duration of remissions and to examine toxicity of cladribine in low-grade lymphomas as first-line therapy or in first relapse using intermittent 2-hour-infusion of cladribine. A total of 294 courses, median of 5 courses per patient, were administered to 66 evaluable patients (53 previously untreated, 13 relapsed) with 5 mg/m2 cladribine given as intermittent 2-hour-infusion over 5 consecutive days for a maximum of 6 cycles every four weeks. Entities: 26 follicle center, 20 lymphoplasmacytoid, 12 mantle cell, 6 T-cell, 2 marginal zone lymphomas. Fifty of 66 patients responded to cladribine corresponding to an overall response rate of 76% (95% confidence interval (95% CI): 64%-85%) with 38% CR (95% CI: 26%-51%) and a median time of remission duration of 23 months (range 6-45+). The overall survival rate at 48 months was 72%. For 49 previously untreated patients with B-cell lymphomas the overall response rate was 86% (95% CI: 73%-94%) with a high CR rate of 43% (95% CI: 29%-58%). Response rate for the group of 23 previously untreated patients with follicle center lymphomas was high with 96% overall response (95% CI: 78%-100%) and 57% CR rate (95% CI: 34%-77%). Cladribine also showed activity in patients with mantle cell lymphomas achieving a response rate of 58% (95% CI: 28%-85%). Myelosuppression was the major toxicity with 17% neutropenia grade 3 and 4. Thrombocytopenia was rare with only 2% grade 3 and 4. A prolonged CD4-lymphocytopenia was observed in all patients. Life threatening complications were not observed. These results confirm the major single-agent activity of cladribine in a large cohort of patients with untreated low-grade lymphomas using the intermittent 2-hour-infusion dosage-regimen. To improve treatment results furthermore, cladribine should be combined with other agents active in low-grade lymphomas.

Positron emission tomography (PET) for staging and evaluation of response to treatment in patients with Hodgkin's disease

Forty two examinations utilizing F-18 FDG-PET were performed in 23 patients with Hodgkin's disease to study for involved lymphoma regions and compared to conventional staging procedures. Twenty stagings were performed at diagnosis of untreated Hodgkin's disease or at first relapse, and 22 restagings during and after chemoradiotherapy. At diagnosis in 5 of 20 patients PET and other procedures revealed different extranodal manifestations and in 3 patients established different clinical staging. PET seemed to be accurate in the assessment of lymphoma involvement in nodal sites. During follow up, in 10 out of 22 investigations different results and discrepancy were recorded, mostly due to the different extent of F-18-FDG metabolism in residual masses in lymphatic tissues compared to CT, X-ray or ultrasonography. The results indicate that PET may have advantages in the assessment of remissions in nodal sites. Less conclusive results were observed with regard to extranodal involvement or inflammatory disease. In conclusion PET may be sufficient for the staging of the majority of patients with Hodgkin's disease and particularly for assessing remission status in nodal sites, but PET may have disadvantages in the evaluation of extranodal lymphoma and inflammatory disease.

Treatment of mantle-cell lymphomas with intermittent two-hour infusion of cladribine as first-line therapy or in first relapse

PURPOSE

Cladribine (2-chlorodeoxyadenosine, 2-CdA) has been reported to be effective in the treatment of low-grade lymphomas. The objective of this multicenter study was to evaluate the activity of cladribine in mantle-cell lymphomas as first-line therapy or in first relapse using an intermittent two-hour infusion of cladribine.

PATIENTS AND METHODS

A total of 47 courses, or an average of four courses per patient, were administered to 12 patients (seven untreated, five relapsed) with 5 mg/m2 cladribine given as an intermittent two-hour infusion over five consecutive days for a maximum of six cycles every four weeks.

RESULTS

Cladribine showed activity in patients with mantle-cell lymphomas, achieving a response rate of 58% (95% confidence interval (95% CI): 28%-85%). Myelosuppression was the major toxicity with 17% of grade 3 and 4 neutropenia. Thrombocytopenia was rare with only 2% of grade 3 and 4.

CONCLUSION

These results demonstrate single-agent activity of cladribine in mantle-cell lymphomas using the intermittent two-hour infusion dosage regimen. To further improve treatment results, cladribine should be combined with other agents active in mantle-cell lymphomas.

Spirometric gated quantitative computed tomography of the lung in healthy smokers and nonsmokers

RATIONALE AND OBJECTIVES

The authors investigated the influence of cigarette smoking on healthy, asymptomatic smokers and nonsmokers with the help of spirometric triggered quantitative computed tomography. In our prospective study, the authors compared conventional lung function parameters with the computed tomography values (lung attenuation, lung area).

METHODS

The study group comprised 40 healthy volunteers consisting of 20 smokers and nonsmokers (20 females and 20 males). The corresponding groups have been matched concerning their age, height, body mass, (cigarette) pack years. Computer tomography scans were triggered at 35%, 50%, 70% and 95% of vital capacity at a defined apical and a basal level.

RESULTS

Functional residual capacity (FRC), total lung capacity and airway resistance showed close correlations to lung parenchymal attenuation values especially at full inspiration and expiration. For example, the authors found a correlation coefficient of r = -0.845 (P < or = 0.001) concerning the FRC and lung attenuation values in the apical lung at 35% of vital capacity in male smokers. Male smokers proved to have a significantly higher pulmonary lung density at all inspiratory states than the other groups (P < or = 0.05; Student's t test). Although male smokers had a higher vital capacity they showed a smaller cross-sectional area increase of the lung during inspiration than nonsmokers. This phenomenon is a result of the decreasing compliance of the smoker's lung, due to small airways disease and hypoxic vasoconstriction.

CONCLUSIONS

Spirometric-triggered quantitative computed tomography has proved to be a sensitive diagnostic device for the investigation of early pathomorphologic changes in healthy, asymptomatic cigarette smokers.