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Bleomycin-induced pulmonary function abnormalities.

The usefulness of serial PFTs in identifying patients who are developing BIP was assessed in 59 men with non-seminomatous testicular carcinoma. The mean age was 27.7 years and all the patients received a standard three-course chemotherapy regimen consisting of vinblastine, bleomycin, and cis-diamminedichloroplatinum. The average dose of bleomycin was 555.5 units. Serial PFTs, chest roentgenograms, and medical assessments were done prior to each course of bleomycin. Nine (15.3 percent) patients developed pulmonary symptoms due to bleomycin and 23 (39 percent) had significant changes on chest x-ray films. The Dsb dropped significantly with bleomycin treatment; therefore, it is the most sensitive indicator of pulmonary response to bleomycin. However, the Dsb failed to differentiate patients with BIP from those without. The TLC was found to be a much more specific indicator of BIP because reduction in TLC correlated with the development of pulmonary symptoms and roentgenologic changes.

Adolescent↗

Effectiveness of bleomycin in comparison to tetracycline as pleural sclerosing agent in rabbits.

The two agents most commonly used for producing a pleurodesis are tetracycline and bleomycin. Tetracycline is no longer available due to more stringent requirements on the manufacturing process. The objective of this project was to determine whether bleomycin is an effective sclerosant in an experimental model in rabbits. The following medications were instilled intrapleurally in anesthetized male rabbits: tetracycline, 35 mg/kg, or bleomycin, 1.5 or 3.0 IU/kg diluted to a total volume of 1 ml with bacteriostatic saline solution. Twenty-eight days after the instillation, the animals were killed, and the pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The intrapleural injection of bleomycin was ineffective in creating pleural fibrosis, either grossly or microscopically. The mean degree of gross pleurodesis in the six rabbits who received tetracycline was 2.7 +/- 1.5 (scale 0 to 4), while that in the rabbits who received the highest dose of bleomycin was 0.0 +/- 0.0. Based on this study, we recommend that bleomycin not be used as a pleural sclerosant in patients with nonneoplastic pleural disease, eg, those with pneumothorax, congestive heart failure or cirrhosis, and pleural effusion.

Analysis of Variance↗

Prospective randomized trial of talc slurry vs bleomycin in pleurodesis for symptomatic malignant pleural effusions.

OBJECTIVE: Symptomatic malignant pleural effusions are common sequelae in patients with certain malignancies. Pleurodesis via bedside thoracostomy is the current treatment option most commonly used. To our knowledge, this is the first prospective randomized trial to examine which agent, bleomycin or talc slurry, is superior in terms of effectiveness, safety, and cost. PATIENTS AND METHODS: Between July 1992 and March 1995, 35 patients presenting to our medical center with symptomatic malignant pleural effusions were prospectively randomized to undergo chemical pleurodesis with either bleomycin or talc slurry via bedside thoracostomy. The conditions of patients were assessed and graded before and after treatment concerning pain, dyspnea, and chest radiographs. RESULTS: Twenty-nine patients who underwent 33 treatments (14 with bleomycin and 19 with talc) were available for follow-up. Follow-up ranged from 2 weeks to 8 months (mean, 1.7 months). Both groups demonstrated notable improvement in both pain and dyspnea following treatment, but there were no statistically significant differences between groups in the amount of improvement (two-tailed Student's t test). Permanent control of effusions, defined objectively on chest radiograph, was achieved with 11 bleomycin treatments (79%) and 17 talc treatments (90%) (p=0.388). The procedures were well tolerated and no significant adverse effects were observed. Talc is a much less costly agent than bleomycin ($12.36 cost to our medical center per treatment for talc vs $955.83 for bleomycin). CONCLUSION: Given the similar efficacy and significant cost advantage, we conclude that talc is the agent of choice when utilizing pleurodesis for control of symptomatic malignant pleural effusions.

Aged↗

Visualization of focal nuclear sites of DNA repair synthesis induced by bleomycin in human cells.

In this study, we examined DNA repair synthesis in human cells treated with the radiomimetic drug bleomycin, which efficiently induces double-strand breaks (DSBs). Using tyramide-biotin to amplify fluorescent signals, discrete nuclear foci from the incorporation of 5-iododeoxyuridine (IdU) were detected in proliferating human cells treated with bleomycin. We believe this comes from the repair of DSBs. An increase in the number of foci (>5 per nucleus) was detected in a major fraction (75%) of non-S-phase cells labeled for 30 min with IdU 1 h after the end of bleomycin treatment. The fraction of cells with multiple IdU-containing foci was found to decrease 18 h after treatment. The average number of foci per nucleus detected 1 h after bleomycin treatment was found to decrease twofold between 1 and 3.5 h, indicating that the foci may be associated with the slow component of DSB repair. The presence of DSBs in bleomycin-treated cells was confirmed using antibodies against phosphorylated histone H2AX (gamma-H2AX), which is strictly associated with this type of DNA damage. After treatment with bleomycin, non-S-phase cells also displayed heterogeneous nuclear foci containing tightly bound proliferating cell nuclear antigen (PCNA), suggesting an ongoing process of unscheduled DNA synthesis. PCNA is known to be involved in base excision repair, but a fraction of the PCNA foci may also be associated with DNA synthesis occurring during the repair of DSBs.

Antibiotics, Antineoplastic↗

Base substitutions, targeted single-base deletions, and chromosomal translocations induced by bleomycin in plateau-phase mammary epithelial cells.

Previous work showed that treatment of plateau-phase Chinese hamster ovary cells with the radiomimetic double-strand cleaving agent bleomycin induced very small deletions as well as interchromosomal reciprocal translocations, both of which could be ascribed to errors in end joining of DNA double-strand breaks. In an attempt to assess the possible role of TP53 in suppressing such repair errors, bleomycin-induced mutagenesis at the HPRT locus was examined in immortalized 184B5 human mammary epithelial cells (TP53(+)), and in a TP53-defective derivative, 184B5-E6tfxc6. For both cell lines, the most frequent bleomycin-induced mutations were base substitutions, with no apparent targeting to major bleomycin lesions. However, both lines also sustained single-base deletions that were targeted to expected sites of double-strand breaks, suggesting that they arose by end-joining repair of the breaks. Surprisingly, only a few large deletions or rearrangements, and no interchromosomal events involving the HPRT locus were detected among the mutants. The results suggest that in both cell lines, errors in double-strand break repair resulting in heritable large deletions and rearrangements are rare. Spectral karyotyping of bleomycin-treated 184B5 cells showed that a significant number of translocations were present shortly after bleomycin exposure, but their frequency decreased upon continued culture of the cells. Thus, for these cells, the lack of induced interchromosomal rearrangements can be explained in part by selection against such events as the cells proliferate.

Base Sequence↗

Mice lacking neutrophil elastase are resistant to bleomycin-induced pulmonary fibrosis.

Neutrophil elastase is a serine protease stored in the azurophilic granules of leukocytes. It has been implicated in the pathology of several lung diseases and is generally presumed to contribute to the tissue destruction and extracellular matrix damage associated with these conditions. To delineate the role of neutrophil elastase in pulmonary inflammation and fibrosis, neutrophil elastase-null mice were intratracheally instilled with bleomycin. In neutrophil elastase-null mice, biochemical and morphological characteristics of pulmonary fibrosis were attenuated for at least 60 days after bleomycin administration despite a typical response to bleomycin as evidenced by assessment of indices of DNA and cell damage. Neutrophil burden of bleomycin-treated wild-type and neutrophil elastase-null mice was comparable, and marked neutrophilic alveolitis was manifest in bleomycin-treated neutrophil elastase-null mice. An absence of immunostaining for active transforming growth factor (TGF)-beta in lung tissue from bleomycin-treated neutrophil elastase-null mice suggested a defect in TGF-beta activation, which was confirmed by biochemical assessment of TGF-beta levels in bronchoalveolar lavage fluid and lung tissue. These data point to novel and unexpected fibrogenic consequences of neutrophil elastase activity in the inflamed lung.

Animals↗

Response of rat incisor mesenchymal cells to doxorubicin after bleomycin pretreatment.

Bleomycin is a possible synchronizing agent of dividing cell populations in vivo. Utilizing this property, we studied doxorubicin-induced alterations in incisor mesenchymal cells by light microscopy in rats pretreated with bleomycin. Two experimental groups were given 25 mg/kg and 75 mg/kg bleomycin, respectively, followed by a dose of 5 mg/kg doxorubicin after 32 h. At that time, the synchronized cells were theoretically entering the synthesis phase of the cell cycle, in which they are most vulnerable to doxorubicin. Animals given 75 mg/kg bleomycin had indications of cell synchronization, resulting in increased destruction of the basal pulp 1 day after doxorubicin administration. Two odontoblast/dentinal lesions were seen on the 5th day of observation, each induced by injury to cells that were late preodontoblasts at the time of bleomycin and doxorubicin injection. The histomorphological alteration seen after the lowest bleomycin dose in combination with doxorubicin included necrosis of basal pulp cells after 1 day and dentinal dearrangements after 5 days, corresponding to what has previously been found in animals given doxorubicin only.

Animals↗

Failure of systemic N-acetyl cysteine to protect the rat lung against bleomycin toxicity.

In order to see whether systemically administered N-acetyl cysteine (NAC) could protect the lung from bleomycin lung injury, 24 rats were given a constant subcutaneous infusion of NAC (mean 195 mg.kg-1.day-1) for 7 days while 23 rats were given a similar volume of saline. Two days after the start of infusion, half of each group received an endotracheal injection of bleomycin and the other half received a similar volume of saline. All animals were killed 7 days after intratracheal injection and their lungs were prepared for wet-weight to dry-weight ratio (W:D) and morphometric assessment of histological changes. In animals given intratracheal saline, NAC infusion had no effect on weight gain, W:D or morphometry compared to those animals given saline infusions. However, all bleomycin-treated animals had obvious evidence of lung damage. Compared to either group of animals treated with intratracheal saline, the bleomycin-treated groups gained less weight (p less than 0.001), had a higher W:D (p less than 0.001) and an increase in the volume densities of alveolar and duct walls (p less than 0.001), intra-alveolar cells (p less than 0.05) and consolidation (p less than 0.001). There were no significant differences between the two bleomycin-treated groups in any parameter measured. It is concluded that administration of NAC by a constant subcutaneous infusion was not protective against bleomycin lung injury.

Acetylcysteine↗

Bombesin down modulates pulmonary fibrosis elicited in mice by bleomycin.

The role of bombesin was investigated in the course of the pulmonary inflammation and fibrosis (PF) elicited by the intratracheal (IT) or intravenous (i.v.) administration of bleomycin in mice. Bleomycin-induced alveolitis was associated with an accumulation of cells, presumably macrophages, containing bombesin, as evidenced by immunohistochemistry. Administration of bombesin by an osmotic minipump implanted IP, at a rate of 6 micrograms/h, decreased the lung hydroxyproline evident 15 days after IV or IT administration of bleomycin. In contrast, antibombesin monoclonal antibody 2A11 (mAb) increased the lung hydroxyproline content after IT administration of bleomycin. In addition, the mortality of bleomycin-injected mice was increased by the anti-bombesin mAb. Bombesin administration induced an increase, and anti-bombesin mAb induced a decrease, in the number of macrophages recovered from the bronchoalveolar lavage. Administration of bombesin did not change the mRNA levels of TNF-alpha, TGF-beta, and PDGF, as seen on Northern blots made with the lung RNA. Pulmonary platelet trapping, which was increased by a bleomycin injection, was decreased by an infusion of bombesin as demonstrated by the distribution of 111In-labeled platelets. This study indicates that bombesin act as an inhibitor of the development of pulmonary fibrosis, possibly by decreasing pulmonary platelet trapping.

Animals↗

Iron complexes and their reactivity in the bleomycin assay for radical-promoting loosely-bound iron.

The sensitivity of the bleomycin assay for loosely-bound iron depends on the concentration of bleomycin and ascorbic acid and the pH of the reaction. The non-haem-iron proteins transferrin, conalbumin and ferritin release iron at an acid pH value, whereas the haem-iron proteins release iron more readily at an alkaline pH. In addition, haem proteins are liable to release iron when peroxides are present. Organic peroxides and hydrogen peroxide can be produced during the bleomycin reaction leading to iron release from haem proteins. However, this can be prevented from reacting with bleomycin by adding zinc ions to the reaction following addition of the sample. Iron already bound to bleomycin is not displaced by zinc whereas zinc bound to bleomycin is not displaced by iron allowing 'free' and 'released' iron to be discriminated.

Ascorbic Acid↗

The role of reactive oxygen species in the antitumor activity of bleomycin.

Calf thymus DNA was incubated with bleomycin and FeCl3 in the presence of isolated rat liver microsomal NADH-cytochrome b5 reductase, cytochrome b5 and NADH which catalyze redox cycling of the bleomycin-Fe-complex. Furthermore, isolated rat liver nuclei were incubated with bleomycin, FeCl3 and NADH, a system in which redox cycling of bleomycin-Fe leads to DNA damage. In both systems free bases from DNA were released. Furthermore, 8-hydroxy-guanine was also found in the supernatant. On the other hand, 8-hydroxy-deoxyguanosine was detected in DNA of cell nuclei indicating that hydroxylation of the guanine molecule occurred in intact DNA. The release of bases correlated with the release of malondialydehyde as well as with NADH and oxygen consumption. These results indicate that NADH-cytochrome b5 reductase catalyzes redox cycling of the bleomycin-Fe-complex which results in the formation of reactive oxygen species which oxidize deoxyribose as well as bases of DNA. Both mechanisms may contribute to the cytotoxic and cytostatic effects of bleomycin observed in intact cells.

8-Hydroxy-2'-Deoxyguanosine↗

GM-CSF regulates bleomycin-induced pulmonary fibrosis via a prostaglandin-dependent mechanism.

To characterize the role of GM-CSF in pulmonary fibrosis, we have studied bleomycin-induced fibrosis in wild-type mice vs mice with a targeted deletion of the GM-CSF gene (GM-CSF-/- mice). Without GM-CSF, pulmonary fibrosis was worse both histologically and quantitatively. These changes were not related to enhanced recruitment of inflammatory cells because wild-type and GM-CSF-/- mice recruited equivalent numbers of cells to the lung following bleomycin. Interestingly, recruitment of eosinophils was absent in GM-CSF-/- mice. We investigated whether the enhanced fibrotic response in GM-CSF-/- animals was due to a deficiency in an endogenous down-regulator of fibrogenesis. Analysis of whole lung homogenates from saline- or bleomycin-treated mice revealed that GM-CSF-/- animals had reduced levels of PGE2. Additionally, alveolar macrophages were harvested from wild-type and GM-CSF-/- mice that had been exposed to bleomycin. Although bleomycin treatment impaired the ability of alveolar macrophages from wild-type mice to synthesize PGE2, alveolar macrophages from GM-CSF-/- mice exhibited a significantly greater defect in PGE2 synthesis than did wild-type cells. Exogenous addition of GM-CSF to alveolar macrophages reversed the PGE2 synthesis defect in vitro. Administration of the PG synthesis inhibitor, indomethacin, to wild-type mice during the fibrogenic phase postbleomycin worsened the severity of fibrosis, implying a causal role for PGE2 deficiency in the evolution of the fibrotic lesion. These data demonstrate that GM-CSF deficiency results in enhanced fibrogenesis in bleomycin-induced pulmonary fibrosis and indicate that one mechanism for this effect is impaired production of the potent antifibrotic eicosanoid, PGE2.

Animals↗

Characterization of bleomycin action on DNA.

Cleavage of SV40 DNA by bleomycin was assayed quantitatively in vitro in the presence of various ppolynucleotides. SV40 DNA was protected from bleomycin- duced cleavage by native or denatured DNA of other origins, oly dG-C.poly dG-C, poly dA-T.poly dA-T and poly dA-T (denatured) but not by tRNA of E. coli, apurinic acid, poly dA, poly dT and various deoxyribooligonucleotides. Various bleomycins and their derivatives and various fragments of bleomycin were tested for possible activity in cleaving SV40 DNA and from the results some structure-activity relationships for the action of bleomycin to act on DNA were outlined. Actinomycin D stimulated bleomycin action while ethidium bromide inhibited it.

Animals↗

Stimulation of prolyl hydroxylase activity by bleomycin.

The activity of purified prolyl hydroxylase (proline, 2-oxoglutarate dioxygenase, EC 1. 14. 11. 2) was enhanced 3 approximately 8-fold at a low concentration of ferrous ion (1 X 10(-5 M) by addition of bleomycin, a glycopeptide antibiotic with antineoplastic activity and a side effect of producing pulmonary fibrosis. The maximum stimulation was attained at a concentration of 15 microgram/ml bleomycin (about 1 X 10(-5) M), which was approximately equimolar with the ferrous ion, one of the cofactors of this enzyme. Addition of bleomycin to the assay mixture resulted in a change of the optimal concentration of ferrous ion from 2 X 10(-3) M to 1 X 10(-5) M. Changing the order of addition of ferrous ion, enzyme and bleomycin in assay medium before incubation at 37 degrees C, the stimulatory activity was varied. Blemycin A2Cu++(Cu++-chelated bleomycin), which scarcely complexed with Fe++, had no enhancing effects on the enzymatic activity. We discuss the possible reasons as to why the activity of prolyl hydroxylase was enhanced by addition of bleomycin in the assay mixture.

Animals↗

Demethylation and auto-oxidation of different cobalt-=bleomycin complexes.

Demethylation of Co-bleomycin A2 by heating yields three different complexes: form I and form II and "orange" Co-bleomycin-demethyl A2. These complexes can be separated by HPLC and show different 1H NMR spectra. Preparation of Co-bleomycin-demethyl A2 by chelation of bleomycin-demethyl A2 with cobalt yields a Co-bleomycin-demethyl A2, which is auto-oxidized into Co-bleomycin A1.

Bleomycin↗

Amplification of the antibiotic effects of the bleomycins, phleomycins and tallysomycins: its dependence on the nature of the variable basic groups.

The bleomycins, phleomycins and tallysomycins are structurally similar glycopeptide antibiotics. Within each class, individual members differ only in the structure of a basic group. The antibiotic effect of phleomycin (Bristol batch A9331-648) against Escherichia coli is amplified substantially by a number of simple heterocyclic and aromatic compounds. In this paper a sample of 26 such compounds were tested for this property with 25 different phleomycins, bleomycins and tallysomycins. The nature of the variable basic group of the phleomycins, bleomycins and tallysomycins determined the response obtained with all amplifiers, although variation of response was much less marked with caffeine which potentiated the cytotoxic effects of all the phleomycins, bleomycins and tallysomycins tested. Phleomycins and bleomycins having two or three guanidino groups in the variable basic group, or phleomycins having a secondary amino group within a methylene chain and a terminal 2-phenylethyl substituent, were amplified by most compounds, whereas the cytotoxicity of others was enhanced little or not at all. Similar phleomycins, having a secondary amino and a terminal guanidino group and no 2-phenylethyl substituent showed little enhancement, and in these cases the inclusion of a 2-phenylethyl substituent had a major influence in determining amplifiability. Bleomycins and phleomycins having identical basic groups were amplified to similar extents by the sample of 26 amplifying agents used.

Bleomycin↗

Fibroblast proliferation by bleomycin stimulated peripheral blood mononuclear cell factors.

OBJECTIVE: To evaluate the role of bleomycin for cutaneous fibrosis, we investigated the effects of bleomycin stimulated peripheral blood mononuclear cell (PBMC) factors on in vitro proliferation of mouse 3T3 fibroblasts. METHODS: PBMC were incubated with 10(-4) to 10 microg/ml of bleomycin, and the supernatants (conditioned media) were collected after 48 h. 3H-TdR incorporation was assayed to examine the effects of conditioned medium on 3T3 fibroblast proliferation, which was also compared between 8 patients with systemic sclerosis (SSc) and 8 control subjects. RESULTS: Conditioned medium stimulated 3T3 fibroblasts to proliferate in a dose dependent manner, while culture supernatant without stimulation of bleomycin showed no growth stimulatory activity. Conditioned medium derived from PBMC of patients with SSc exhibited a significantly higher growth activity than that from controls (p < 0.05). Among PBMC subpopulations, macrophages showed the most increased growth effect on 3T3 fibroblasts, although T lymphocyte populations also showed growth activity. The growth activity was inhibited up to 35% by anti-platelet derived growth factor (PDGF) antibody. In addition, growth activity was also partially blocked by antibodies against basic fibroblast growth factor (bFGF) (20%), interleukin 1beta (IL-1beta) (15%), tumor necrosis factor-alpha(TNF-alpha) (7.9%), and transforming growth factor-beta (TGF-beta)(9.5%). The cellular release of IL-1beta, TNF-alpha, and IL-6 was elevated in response to bleomycin exposure in both controls and patients with SSc. Reverse transcriptase-polymerase chain reaction revealed that conditioned medium derived from both patients with SSc and controls induced mRNA expression of several fibrogenic cytokines such as IL-6, TNF-alpha, TGF-beta, and PDGF. IL-1alpha was induced only by conditioned medium derived from patients with SSc. CONCLUSION: These results suggest that bleomycin induced cutaneous fibrosis as well as pulmonary fibrosis may be induced by inflammatory cells through several fibrogenic cytokines.

3T3 Cells↗

Neutralization of the CXC chemokine, macrophage inflammatory protein-2, attenuates bleomycin-induced pulmonary fibrosis.

Few studies have addressed the importance of vascular remodeling in the lung during the development of bleomycin-induced pulmonary fibrosis. For fibroplasia and deposition of extracellular matrix to occur, there must be a geometric increase in neovascularization. We hypothesized that net angiogenesis during the pathogenesis of fibroplasia and deposition of extracellular matrix during bleomycin-induced pulmonary fibrosis are dependent in part upon an overexpression of the angiogenic CXC chemokine, macrophage inflammatory protein-2 (MIP-2). To test this hypothesis, we measured MIP-2 by specific ELISA in whole lung homogenates in either bleomycin-treated or control CBA/J mice and correlated these levels with lung hydroxyproline. We found that lung tissue from mice treated with bleomycin, compared with that from saline-treated controls, demonstrated a significant increase in the presence of MIP-2 that was correlated to a greater angiogenic response and total lung hydroxyproline content. Neutralizing anti-MIP-2 Abs inhibited the angiogenic activity of day 16 bleomycin-treated lung specimens using an in vivo angiogenesis bioassay. Furthermore, when MIP-2 was depleted in vivo by passive immunization, bleomycin-induced pulmonary fibrosis was significantly reduced without a change in the presence of pulmonary neutrophils, fibroblast proliferation, or collagen gene expression. This was also paralleled by a reduction in angiogenesis. These results demonstrate that the angiogenic CXC chemokine, MIP-2, is an important factor that regulates angiogenesis/fibrosis in pulmonary fibrosis.

Animals↗