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M Demedts

Publications and source records attributed to M Demedts.

At least 73 records · Page 4Linked to original sources
PubMed1997

Increase in gamma-glutamyltransferase by glutathione depletion in rat type II pneumocytes.

The purpose of our study was to investigate the effect of oxidative stress or intracellular glutathione (GSH) depletion on gamma-glutamyltransferase (gamma-GT) activity in cultured type II pneumocytes. Twenty-four hours after isolation, primary cultures of rat type II pneumocytes were preincubated with one of four compounds: 15, 30, 60, 125, 250 microM L-buthionine-[SR]-sulfoximine (BSO) for 3 h; 100, 200, 400, 800 microM tertiary-butylhydroperoxide (t-BOOH) for 45 min; 10, 25, 50, 100 microM menadione for 15 min; 100, 1000 microM paraquat for 1 h. GSH levels, H2O2 and O2.- generation were measured immediately after the incubation, gamma-GT activity and GSH levels also up to 24 h or 48 h later. Exposure to BSO led to a persistent GSH depletion without increase in H2O2 or O2.- production, together with a dose and time-dependent increase (doubling) of gamma-GT activity with a nonsignificant increase in gamma-GT mRNA expression 24 h after exposure to BSO. Exposure to 100 microM menadione, which increased H2O2 production, decreased gamma-GT activity. t-BOOH or paraquat did not give rise to a measurable increase in H2O2 or O2.-. Paraquat did not affect initial GSH levels, but increased GSH and decreased gamma-GT activity 24 h later. t-BOOH (400 and 800 microM) initially decreased GSH, and tended to increase GSH 24 h later, 100 and 200 microM increased gamma-GT activity 24 h later, but 800 microM decreased it. Restoration of intracellular GSH levels by addition of GSH to the culture medium completely prevented the increase in gamma-GT activity by BSO, while the addition of catalase or DMTU had no effect. We conclude that at least two effects are operating upon gamma-GT activity: GSH depletion seems to increase gamma-GT activity, while exposure to compounds generating oxidative stress correlates with a decrease in gamma-GT activity.

Animals↗
PubMed1997

Putrescine uptake in rat type II pneumocytes correlates with gamma-glutamyltransferase activity.

gamma-Glutamyltransferase (gamma GT) is a key enzyme in glutathione metabolism and it is thought also to play a role in the uptake of polyamines such as putrescine. The aim of our study was to investigate if changes in gamma GT activity would alter total putrescine uptake [P(up)(tot)], as well as more specific uptake via the gamma GT pathway [P(up)(gamma GT)]. Forty-eight hours after their isolation, rat type II cells were exposed to 30, 60 or 125 microM L-buthionine-[SR]-sulfoximine (BSO) for 3 hr; 200 or 800 microM tertiary-butylhydroperoxide (t-BOOH) for 40 min; 10, 100 or 1000 microM paraquat (PQ) for 1 hr; and 60 or 85% O2 for 48 hr. The gamma GT activity, P(up)(tot) and P(up)(gamma GT) (assessed by inhibiting gamma GT) were measured immediately after the exposure to hyperoxia, or 24 hr after treatment with BSO, t-BOOH or PQ. From previous studies, it is known that these experimental conditions increased (BSO, 200 microM t-BOOH) or decreased (800 microM t-BOOH, PQ, hyperoxia) gamma GT activity. There was a strong correlation between the changes in gamma GT activity and the changes in P(up)(gamma GT) (r = 0.81, p < 0.001). These findings support the hypothesis that gamma GT partly regulates the uptake of putrescine, one of the polyamines required for cell growth and differentiation.

Animals↗
PubMed1997

In vitro modulation of the P450 activities of hamster and human lung slices.

The respiratory tract is a portal of entry for many environmental chemicals. The respiratory tract plays an important role in the detoxification or metabolic activation of these chemicals, e.g., via cytochrome P450 enzymes. Alterations in the capabilities of these enzymes to metabolize inhaled compounds can, therefore, affect the toxicity of the chemicals. The pulmonary cytochrome P450 activity has been studied in many species, but relatively little is known about this activity in the human lung tissue. In this limited study, we have investigated the possibility of modulating in vitro the P450 activity in lung slices from hamsters and humans. The alkoxyresorufin-O-dealkylase activity was measured in the S9 fraction of lung slices incubated for 24 h with 10(6) mol/L 20-methylcholanthrene (3MC) or beta-naphthoflavone (beta N). The ethoxyresorufin-O-deethylase (EROD) activity was increased by 3MC and beta N in lung slices of both species. The benzyloxyresorufin-O-deethylase (BROD) activity was decreased after incubation with 3MC but increased with beta N. These data show that in vitro modulation in lung slices is feasible, although technical improvement is still needed, particularly in relation to the viability of the slices.

Animals↗
PubMed1997

In vitro toxicity of cobalt and hard metal dust in rat and human type II pneumocytes.

It has been demonstrated that hard metal dust, which consists of a mixture of cobalt and tungsten carbide, is more toxic toward mouse peritoneal and rat alveolar macrophages than pure cobalt (Co) or tungsten carbide (WC). The aim of this study was to investigate the toxic effects of Co and hard metal dust on alveolar epithelial type II cells (AT-II), and to compare these with alveolar macrophages. Freshly isolated rat and human AT-II and rat alveolar macrophages were exposed for 18 hr to particles of Co, WC or Co/WC. As an index for cell toxicity, release of lactate dehydrogenase was measured. For rat AT-II, TD50 values per 10(5) cells were 672 micrograms (95% C.I. = 264-1706 micrograms) for pure Co and 101 micrograms (95% C.I. = 59-172 micrograms) for Co in Co/WC mixture. For rat alveolar macrophages, TD50 values per 10(5) cells were 18 micrograms (95% C.I. = 15-24 micrograms) for pure Co and 5 micrograms (95% C.I. = 5-6 micrograms) for Co in Co/WC mixture. WC only caused an increase in lactate dehydrogenase at high concentrations. No toxicity was found in human AT-II for either Co, WC or Co/WC. These results indicate that 1) rat AT-II are less sensitive to Co than rat alveolar macrophages, 2) human AT are less sensitive to Co than rat AT-II, 3) the toxicity of Co is increased by the presence of WC.

Animals↗
PubMed1997

Pulmonary toxicity of components of textile paint linked to the Ardystil syndrome: intratracheal administration in hamsters.

OBJECTIVES: It was hypothesised from an epidemiological investigation that a formula change from Acramin FWR (a polyurea) to Acramin FWN (a polyamide-amine) had led to severe pulmonary disease in textile printing sprayers in SPAIN AND ALGERIA. To verify this, the pulmonary toxicity of the components of the paint systems involved was assessed in experimental animals. METHODS: Individual components and relevant mixtures, diluted in phosphate buttered saline, were given by intratracheal instillation of 2 ml/kg to hamsters. Pulmonary toxicity was assessed on days 3, 7, 14, 28, and 92 after a single intratracheal instillation, by histology and by measuring wet and dry lung weight, protein concentration, the activities of lactate dehydrogenase, alkaline phosphatase, beta-N-acetyl-glucosaminidase, and gamma-glutamyltransferase, inflammatory cell number and distribution in bronchoalveolar lavage fluid (BALF), and hydroxyproline content in dried lung tissue. RESULTS: Based on the doses that killed 50% of the animals (LD50s), the various components were found to be 10 to 1250 times more toxic when given intratracheally than when given orally (according to reported oral LD50s in rats). Acramin FWN, Acramin FWR, Acrafix FHN, or their mixtures caused lung damage. Protein concentration, enzyme activities, total cell number, and percentage of polymorphonuclear neutrophils were increased in BALF during the first week after intratracheal instillation. Lung weights remained high for at least a month. Histology showed inflammatory cell infiltration and subsequent fibrosis with collagen deposition. This finding was confirmed by an increased hydroxyproline content in dried lung tissue. Acramoll W did not show toxic effects. CONCLUSIONS: The study suggests that there is no major difference, in hamsters, between the acute intratracheal toxicity of Acramin FWR and that of Acramin FWN. Consequently, there is no simple toxicological explanation for the epidemiological hypothesis. However, the pulmonary toxicity of these non-irritant polymeric compounds is surprisingly high. The Ardystil disaster and these results should serve as a strong warning that conventional toxicity testing of chemicals does not necessarily protect workers against respiratory toxicity.

Acetylglucosaminidase↗
PubMed1997

Involvement of an NAD(P)H oxidase-like enzyme in superoxide anion and hydrogen peroxide generation by rat type II cells.

BACKGROUND: Although alveolar macrophages are considered to be the primary cellular mediators of host defence in the lung, there is increasing evidence that type II cells may also play an active role in host defence. A study was undertaken to investigate whether type II cells generate O2-. and H2O2 via an NADPH oxidase-like system and whether exposure of the type II cells to soluble or particulate stimuli known to activate NADPH oxidase in macrophages also leads to increased production of H2O2. METHODS: Rat type II cells and alveolar macrophages were exposed to 10, 100, or 1000 nM phorbol-12-myristate-13-acetate (PMA) and the production of O2-. and H2O2 was determined by chemiluminescence. Thirty minutes before stimulation with 1 microM PMA type II cells were also exposed to the same concentrations of a protein kinase C (PKC) antagonist GF109203x, the non-selective protein kinase inhibitor staurosporine (1, 10, or 100 nM), or the NADPH oxidase inhibitor diphenyliodonium chloride (DPI) (1, 10, 100, or 1000 microM). The effects of arachidonic acid, zymosan and Staphylococcus aureus on H2O2 production were determined. Cell membrane fractions from type II cells and macrophages were assayed for NADPH oxidase activity. RESULTS: After exposure to 1 microM PMA, O2-. and H2O2 generation increased 6.3-fold and 9.0-fold, respectively, in type II cells and 2.4-fold and 5.2-fold, respectively, in macrophages. In contrast to the macrophages, the increase in O2-. and H2O2 generation by type II cells was completely prevented by 1 mM KCN. Preexposure to GF109203x, staurosporine, or DPI completely prevented the rise in O2-. and H2O2 generation. Mean (SD) NADPH oxidase activity of 138 (38) nmol O2-./min/mg protein was found in membrane fraction I of the type II cells, and 102 (31) nmol O2-./min/mg protein in fraction II. Macrophages showed higher NADPH oxidase activity in membrane fraction II. In type II cells exposure to arachidonic acid led to a significant 5.3-fold increase in H2O2 generation, exposure to zymosan increased H2O2 generation 46-fold, and exposure to S aureus 25-fold with a maximum 30-50 minutes after addition of the bacteria. CONCLUSIONS: Type II cells generate O2-. and H2O2 via a PKC-mediated activation of an NAD(P)H oxidase-like membrane bound enzyme. Arachidonic acid, zymosan, and bacteria also give rise to increased H2O2 production. Type II cells might thus play an active role in host defence.

Animals↗
PubMed1997

Changes in gamma-glutamyltransferase activity in rat lung tissue, BAL, and type II cells after hyperoxia.

The effect of hyperoxia on gamma-glutamyltransferase (gamma-GT), an important enzyme for the uptake of precursor molecules for intracellular synthesis of glutathione (GSH), has not been established. Our aim was to investigate the effects of prolonged subtoxic levels of hyperoxia on gamma-GT activity and GSH levels in lung tissue, epithelial lining fluid (ELF), and isolated rat type II cells immediately after their isolation and 48 h later when kept in culture in normoxia. Seventeen male Wistar rats were divided in three groups (n = 5-7) and were exposed to air or to 60 or 85% O2 for 7 days. Pulmonary gamma-GT activity increased in the 60 and 85% O2-exposed animals (1.6- and 3.2-fold, respectively), and tissue GSH levels increased only in the 60% O2 group (1.3-fold). In isolated type II cells from 60 and 85% O2-exposed animals, gamma-GT activity decreased by -70 and -88%, respectively, which was supported by cytochemical staining. Type II cell gamma-GT mRNA expression tended only to decrease after 85% O2. Type II cell gamma-GT activity strongly correlated with ELF gamma-GT (r = 0.60, P < 0.001), and ELF gamma-GT strongly correlated with ELF GSH (r = 0.75, P < 0.0001). When in culture, type II cell gamma-GT activity and GSH levels remained, respectively, 2.5- and 1.9-fold lower in the 60% O2-exposed group, but, in the 85% O2-exposed group, gamma-GT activity increased 2.1-fold, and GSH levels dropped to the levels of the control cells. Hyperoxia led to a concentration-dependent decrease in gamma-GT activity in rat type II cells, possibly by direct inactivation, but led to an increase in whole lung tissue gamma-GT. There seemed to be a negative feedback between intracellular GSH levels and type II cell gamma-GT activity. gamma-GT levels in the ELF were correlated with type II cell gamma-GT activity, but ELF gamma-GT did not seem to play an active role in the regulation of the ELF GSH pool. Hyperoxia decreased ELF GSH levels, possibly by increased degradation of GSH in the parenchymal lung tissue as a result of the increased gamma-GT activity.

Alkaline Phosphatase↗
PubMed1997

N-acetylcysteine does not protect against type II cell injury after prolonged exposure to hyperoxia in rats.

Although the antioxidant properties of N-acetylcysteine (NAC) in vitro are widely accepted, the efficacy of NAC in the prevention of O2 toxicity in vivo is poorly documented. The aim of our study was to investigate the presumed protective effect of NAC on hyperoxic lung injury, focusing on gamma-glutamyltransferase (gamma-GT) activity and glutathione (GSH) levels in lung tissue, epithelial lining fluid (ELF), and isolated rat type II cells immediately after their isolation and 48 h later when kept in culture in normoxia. Thirty-four male Wistar rats were divided in three groups (n = 10-14) and were exposed to air or to 60 or 85% O2 for 7 days. One-half of the rats in each group received 200 mg/kg NAC intraperitoneally one time per day from 3 days before exposure until the end of the experiment, and the other one-half received the vehicle. In the 85% O2-exposed animals, NAC led to more respiratory distress and weight loss. NAC did not prevent the rise in bronchoalveolar lavage lactate dehydrogenase and alkaline phosphatase, but it did prevent the rise in calculated ELF volume. NAC decreased GSH levels (1.4-fold) and gamma-GT activity (1.8-fold) in the air-exposed type II cells. In the 60% O2-exposed group, no effects of NAC were seen (except for a decrease in gamma-GT mRNA expression), but, in the 85% O2-exposed group, NAC gave rise to higher GSH (2.6-fold) and higher gamma-GT activity (2.9-fold) in the ELF and lower GSH (6.9-fold) and higher gamma-GT activity (3.6-fold) in the type II cells. Even in culture, GSH levels remained 1.5-fold lower than in the cells from the air-exposed animals and 2-fold lower than in the cells from the 85% O2-exposed animals. There was increased DNA damage (as assessed by thymidine incorporation) and apoptosis after hyperoxia, especially after 60% O2, and this effect was amplified after NAC treatment. Although protective at the endothelial side, NAC treatment led to adverse effects at the epithelial side, despite, or probably because of, restoration of the ELF GSH levels in the presence of high O2 levels. Because NAC is rapidly metabolized to cysteine, it is plausible that the effects of NAC are manifested through the toxic effects of cysteine.

Acetylcysteine↗
PubMed1997

Effects of oxygen pressure and medium volume on the toxicity of paraquat in rat and human type II pneumocytes.

The herbicide, paraquat is highly toxic for mammals, with the lungs being the main target organ, because of the active accumulation of the compound in this organ. The cellular toxicity of paraquat has been shown to be an O2-driven process and hyperoxia is known to increase the lethality of paraquat. In this study we have examined the effect of various O2 concentrations on the toxicity of paraquat in rat and human type II pneumocytes in culture, and we have tested whether the thickness of the liquid layer above the cells would influence the toxicity of paraquat. Type II pneumocytes were isolated from rat or human lung tissue using trypsin digestion, percoll density gradient centrifugation and differential attachment. Adherent cells (day 2) were incubated for 20 h in different volumes of culture medium (thickness of liquid layer), whether or not in the presence of paraquat, in the presence of different O2 tensions. The viability of the cells was assessed by the release of LDH in the culture medium. In both rat and human type II pneumocytes the toxicity of paraquat was independent of the thickness of the liquid layer (2.5 to 10 mm height). The toxicity of paraquat in rat type II pneumocytes decreased from a TC50 value of 28 microM paraquat at 21% O2 to 107 microM at 10% O2 and increased to 12 microM and 8 microM at 60% and 85% O2, respectively. For human type II pneumocytes the TC50 values were 7 microM; 25 microM and > 1000 microM paraquat at 60%, 21% and 10% O2, respectively. In this study we have shown that the diffusion of O2 through a liquid layer does not limit the toxicity of paraquat and that, as in vivo, increasing O2 partial pressure enhances the toxicity of paraquat.

Animals↗
PubMed1997

Respiratory dysfunction in multiple sclerosis: a prospective analysis of 60 patients.

This study aimed to determine the relationship between pulmonary function, respiratory muscle function and neurological function in multiple sclerosis (MS). Sixty patients (27 males and 33 females) aged 27-75 yrs (mean +/- SD 48 +/- 12 yrs) were prospectively studied. The Kurtzke Expanded Disability Status Scale (EDSS; range 0-10) score was 6.5 +/- 1.5; and the different Functional Systems Scores (FSS; ranges 0-5 and 0-6) were: pyramidal 3.4 +/- 1.1; brain stem 1.9 +/- 1.2; mental 1.3 +/- 0.9; cerebellar 2.2 +/- 1.0; sphincter 1.8 +/- 1.5; visual 1.4 +/- 1.4; and sensory 2.0 +/- 1.5. Results of lung function tests were: vital capacity (VC) 80 +/- 23% of predicted; single-breath transfer factor of the lung for carbon monoxide (TL, CO, sb) 83 +/- 17% pred; maximal static expiratory mouth pressure (MEP) 30 +/- 16% pred; and maximal static inspiratory mouth pressure (MIP) 47 +/- 23% pred, indicating a marked respiratory muscle dysfunction, with a minor restrictive defect. In 70% of the patients, a transcutaneous oxygen saturation (Stc, O2) of less than 92% at night was found. Comparison of lung function and disability scores showed that the abnormalities in both tended to be correlated to each other, and that this was significant for EDSS versus lung volumes, for most FSS with VC, and also for some FSS with MEP and/or MIP. Duration of disease was significantly correlated with the EDSS, but not with the different FSS scores (with the exception of mental status) and not with lung function. Multiple sclerosis leads to lung function abnormalities attributable to respiratory pump dysfunction.

Adult↗
PubMed1997

Cellular glutathione turnover in vitro, with emphasis on type II pneumocytes.

The most important extracellular antioxidant in the lung is glutathione (GSH). The epithelial lining fluid of normal lungs contains very high concentrations of this tripeptide, about 100 times higher than that found in the extracellular fluid of many other tissues. How these high extracellular GSH levels are established and the mechanisms for increases (e.g. smokers) or decreases (e.g. lung fibrosis) are still unknown, but more insight into the regulation of GSH turnover in type II pneumocytes has recently become available. The purpose of this review is to give an overview of the literature concerning cellular GSH turnover for different cell types in vitro, with an emphasis on alveolar type II epithelial cells. The main messages of this review are that: 1) GSH is, in fact, an important vehicle for stabilizing, detoxifying and transferring cysteine; 2) cysteine is the rate-limiting substrate for GSH synthesis, especially under conditions of oxidative stress; 3) various transport systems exist for the uptake of the constituents of GSH, of which gamma-glutamyltransferase appears to be important; 4) intracellular GSH levels of the type II cells are governed by different factors, including, probably, the extracellular redox state; and 5) a more reduced extracellular redox state appears to favour GSH efflux, whilst an oxidized state leads to retention of GSH inside the cell. These concepts should lead to reconsideration of some of the conventional approaches to increasing intracellular glutathione levels.

Animals↗
PubMed1997

Relief of sleep apnoea after treatment of acromegaly: report of three cases and review of the literature.

Sleep apnoea syndrome (SAS) is common in acromegalic patients. Occasionally, the relief of apnoeas after treatment of the acromegaly has been documented. We report the cases of three patients with acromegaly and severe obstructive sleep apnoea, who demonstrated a manifest improvement (respiratory disturbance index (RDI) <20) after treatment with octreotide, indicating that this drug may be effective in this disturbance. In one case, SAS disappeared although the growth hormone level was not fully normalized. This raises the intriguing hypothesis that octreotide has an effect on respiratory control or on the upper airway, that is not directly related to its action on production of growth hormone.

Acromegaly↗
PubMed1997

Tuberculosis in asylum seekers in Belgium. VRGT (Flemish Lung and Tuberculosis Association).

Countries with a low incidence of tuberculosis have recently been faced with the problem of tuberculosis (TB) in asylum seekers from countries with a high TB prevalence. We report on the tuberculosis case notification rate (TBCNR) in Belgium in 1993, and on the results of active screening in a group of asylum seekers. The TBCNR in Belgium in 1993 increased slightly to 14.9 per 100,000, mainly due to the nonindigenous population. The highest TBCNR (312 per 100,000) was reported among the 26,882 asylum seekers staying in Belgium in 1993. Of all new asylum seekers admitted in 1993, 4,794 agreed to undergo radiographic screening for TB at entry, of whom 123 had a chest radiograph which was suspect. Among the 123, 67 could be further investigated, and, of these, 19 cases (28%) of active TB were detected; this represents a TBCNR of 396 per 100,000 when referred to the 4,794 asylum seekers screened. In addition, 56 asylum seekers with suspect chest radiograph were lost to further investigation. From the present results it appears that: 1) in Belgium, asylum seekers constitute an important risk group for TB, with a TBCNR after screening which is approximately 30 times that in the indigenous population; and 2) there is a deficient follow-up after first screening, generating the risk of transmission of TB within the community. Our recommendations are, therefore, that in all asylum seekers screening for tuberculosis should be mandatory and follow-up of active tuberculosis should be regulated.

Adolescent↗
PubMed1996

Verapamil as prophylactic treatment for atrial fibrillation after lung operations.

BACKGROUND: Atrial fibrillation is a frequently occurring arrhythmia after thoracic operations. Preventive strategies for this complication have been extensively evaluated after cardiac operations. METHODS: We performed a prospective, open randomized study, comparing intravenous verapamil and placebo in 199 patients after pneumonectomy or lobectomy at the University Hospital of Leuven. Verapamil was administered as a bolus of 10 mg over 2 minutes followed by a 30-minute infusion of 0.375 mg/min and then 0.125 mg/min for 3 days. The patients were continuously monitored in the postoperative intensive care unit. RESULTS: Atrial fibrillation occurred in 15% of the patients receiving placebo and in 8% of the patients receiving verapamil (difference not significant). The verapamil infusion was interrupted in 9% of the patients because of bradycardia and in 14% because of hypotension. CONCLUSIONS: If tolerated, continuous intravenous verapamil infusion showed only a modest prophylactic efficacy for the occurrence of atrial fibrillation after lung operations. In the dose employed the verapamil infusion was accompanied with a high incidence of side effects necessitating interruption of the therapy.

Amiodarone↗
PubMed1996

Assessment of the ear swelling test and the local lymph node assay in hamsters.

In a hamster model, we compared contact sensitivity to the metal salt, potassium dichromate, to that of oxazolone, a well-known strong sensitizing agent. Using the ear swelling test, originally developed in mice, no significant differences could be observed between animals treated with potassium dichromate and controls, although oxazolone-treated animals showed a significant increase in ear thickness compared to controls. These observations were confirmed using the local lymph node assay (LLNA) where oxazolone proved to be a strong sensitizing agent, and potassium dichromate only resulted in a weak response. When the draining auricular lymph nodes were compared with the inguinal lymph nodes in the LLNA, more pronounced effects were obtained with the auricular lymph nodes. This study indicates that, also in hamsters, the LLNA is a feasible sensitization test system.

Animals↗
PubMed1996

Bronchogenic cysts: a review of 20 cases.

OBJECTIVE: All cases of bronchogenic cysts treated in our center are analysed in order to define its clinical and pathological features. These data are used to determine whether surgical treatment in all cases is justified or whether there is a place for conservative treatment. METHODS: We retrospectively studied the medical records and pathology reports of all patients with bronchogenic cysts (n = 20) referred to our clinic between 1975 and 1993. RESULTS: Fourteen patients (70%) were asymptomatic. Six patients had symptoms because of cyst-related complications (infection or compression). In only 15 patients the diagnosis was established preoperatively. In the other five cases a solid tumour was suspected. All patients were treated by either thoracotomy (n = 19) or thoracoscopy (n = 1). The diagnosis was confirmed by histological examination. One cyst turned out to be degenerated into a squamous cell carcinoma. CONCLUSIONS: We conclude that both the risk of developing cyst-related complications and the even smaller risk of malignant degeneration justify surgical treatment in all cases.

Adult↗
PubMed1996

Putrescine accumulation in human pulmonary tumours.

Type II pneumocytes and Clara cells, both epithelial cells that possess an active uptake system for polyamines, have been identified as possible precursor cells of at least some types of lung tumours. In this study we have investigated whether human pulmonary tumours exhibit putrescine uptake. Lung slices from both tumoral tissue and non-tumoral tissue, obtained from patients undergoing surgery for lung cancer, were incubated with radiolabelled putrescine at both 37 degrees C and 4 degrees C. The accumulation of putrescine was evaluated by its apparent kinetic parameters, in the presence or absence of cystamine, and by autoradiography. The investigated tumoral tissue (six squamous carcinomas and five adenocarcinomas) did not show accumulation of putrescine above that attributable to simple diffusion, except for one adenocarcinoma. In this specimen autoradiography showed that the accumulation was not specifically associated with any particular cell type, but that practically every cell accumulated putrescine. We conclude that human pulmonary tumours do not accumulate polyamines in a manner similar to normal pulmonary epithelial cells.

Adenocarcinoma↗