Paradoxical effects of bleomycin and heavy water (D₂O) in mice

Abstract

Bleomycin (BLM) lacks many side effects of other cytostatic drugs. Pulmonary toxicity is the major dose-limiting effect of BLM. This is based in part on generation of free radicals. It is conceivable that deuterium in body fluids lessens the production of free radicals, thus preventing or diminishing the morphologic expression of pulmonary BLM toxicity. We therefore studied the effect of moderate deuteration of body fluids on BLM-induced lung damage in BALB/c-mice. In addition to conventional histopathological methods, we used a vertical sectioning design for stereological estimation of pulmonary volumes and surface areas. BLM (low/medium/high dose: 25/50/75 IU/kg body weight) was injected i.p. once a week for 6 weeks. Half the mice drank deuterated water before, during and after BLM treatment. Three weeks after the last injection, the lungs were fixed by airway instillation. Deuterated animals treated with BLM lacked signs of irreversible BLM-induced pulmonary damage. Conversely, focal sub-pleural fibrosis and fibrosing alveolitis were present in BLM-treated mice drinking tap water. Deuterated mice had stereological values for almost all lung parameters that were lower than in non-deuterated mice. The organ-specific advantage of deuteration was offset by marked enhancement of systemic toxicity of BLM. We conclude that (1) moderate concentrations of deuterium may prevent the development of fibrosing alveolitis in BLM-treated mice, possibly by reducing proliferation of alveolar fibroblasts, and, less probably, by impairing generation or enhancing capture of free radicals; (2) the toxicity of BLM was enhanced by ingestion of deuterium, resulting in morphological liver alterations and increased mortality.

DOES LACK OF Cftr GENE LEAD TO DEVELOPMENTAL ABNORMALITIES IN THE LUNG?

“…As found in another study in mice [ 17] , a signi cant tissue shrinkage may take place under plastic embedding. Thus, the Cavalieri method may be unreliable to estimate the total volume of small organs ( e.g., mice lungs) , when the latter are submitted to ethanol dehydration and methylmethacrylate embedding.…”

“…For unbiased stereological analysis of surface areas in lungs, a vertical sectioning design [ 16] , adapted to mouse lungs [ 17] , was used ( Figure 1) . Each lung was dissected into left lung, right lung, and accessory lobe by cutting off the extrapulmonary airways at the hilum.…”

“…The slices were then placed on a transparent acetate foil, xeroxed on paper with a calibration scale, and re-embedded in agar to maintain their orientation. Every second slice ( with random start) was dehydrated in a graded series of ethanol and embedded in methylmethacrylate ( 4 parts methylmethacrylate et al [ 13] , Gaeng et al [ 17] :…”

Deuterium Oxide (D2O) Induces Early Stress Response Gene Expression and Impairs Growth and Metastasis of Experimental Malignant Melanoma

“…Since its initial discovery as a natural heavy isotope variant of dihydrogen oxide ( 1 H 2 O), extensive research has focused on the toxicological, biochemical, and pharmacological effects of deuterated water ( 2 H 2 O (D 2 O, also referred to as 'heavy water')) [1]. The pharmacokinetics of tissue deuteration through systemic administration of D 2 O have been studied in much detail in mammalian systems, including mice, and feasibility and toxicological consequences of long-term systemic administration of D 2 O through drinking water supplementation (20% and above) have been investigated [2][3][4][5][6][7][8][9][10]. Administration of D 2 O reaching up to 23% has been documented in investigational human studies for numerous purposes including determination of body water composition and use of D 2 O as a potential modulator for neutron capture therapy (in the context of nuclear medicine) [8,[10][11][12].…”

“…Importantly, shortly after its initial discovery by Urey in 1932, cancer-directed effects of D 2 O (administered systemically) have been examined in vivo, and inhibitory effects on murine tumor growth were described as early as 1938, documenting growth inhibition of implanted mammary carcinoma and lymphosarcoma using D 2 O drinking water supplementation (20-40% (v/v), over a period of nineteen days) [1,2]. Cumulative evidence now confirms tumor-directed activity of D 2 O supplementation in murine cancer models including pancreatic, colorectal, and squamous cell carcinoma [2,3,[5][6][7]9]. However, the specific mechanisms underlying D 2 O-associated chemotherapeutic effects targeting cancer cells remain largely unexplored.…”