ABSTRACT
Skin wound healing exhibits type III collagen synthesis occurring transiently as early as 10 h after injury, with subsequent synthesis of type I to form a scar. We hypothesized that similar collagen type switching also occurred in the bleomycin model of lung fibrosis in the rat. We could measure elevated lung collagen synthesis rates as early as 4 days after administration of bleomycin. Collagen type I:III ratios in whole lung remained constant for the first 7 days at the control level of 2:1, then increased to as high as 5:1 at day 21. Procollagen mRNA content, expressed as a ratio of type I:III mRNAs, was consistent with the protein synthesis data and the observed ratio of collagen types being made by the lungs at the various time points evaluated. We conclude that a transient increase in type III relative to type I collagen does not occur in the bleomycin rat lung model. Therefore, the sequence of type-specific collagen expression and deposition in the skin wound healing model is not entirely analogous to this widely used animal model of pulmonary fibrosis.
Subject(s)
Antibiotics, Antineoplastic/toxicity , Bleomycin/toxicity , Collagen/biosynthesis , Lung/drug effects , Lung/metabolism , Animals , Blotting, Northern , Kinetics , Male , Procollagen/biosynthesis , Pulmonary Fibrosis/metabolism , RNA, Messenger/biosynthesis , Rats , Rats, Sprague-Dawley , Silicon Dioxide/toxicityABSTRACT
During the past 10 years, the use of methamphetamine has increased rapidly in the West and throughout the United States. Because of this increase, our attention has focused on methamphetamine's toxicity. Methamphetamine and related compounds generate many of the same toxic effects as cocaine. Because of methamphetamine's widespread use, clinicians should be familiar with its medical effects and toxicity and with treatment options for acute and long-term effects of methamphetamine abuse.
Subject(s)
Amphetamine-Related Disorders , Central Nervous System Stimulants/chemistry , Methamphetamine/chemistry , Cardiovascular System/drug effects , Central Nervous System/drug effects , Central Nervous System Stimulants/adverse effects , Central Nervous System Stimulants/toxicity , Humans , Methamphetamine/adverse effects , Methamphetamine/toxicityABSTRACT
Daily marijuana smoking has been clearly shown to have adverse effects on pulmonary function and produce respiratory symptomatology (cough, wheeze, and sputum production) similar to that of tobacco smokers. Based on the tobacco experience, decrements in pulmonary function may be predictive of the future development of chronic obstructive pulmonary disease (COPD). However, in the absence of alpha-1-antitrypsin deficiency, the habitual marijuana-only smoker would likely have to smoke 4-5 joints per day for a span of at least 30 yr in order to develop overt manifestations of COPD. The mutagenic/carcinogenic properties of marijuana smoke are also well-established. The potential for induction of laryngeal, oropharyngeal, and possibly bronchogenic carcinoma from marijuana has been documented by several case reports and observational series. Despite this, a relative risk ratio for the development of these tumors has not yet been quantified. Based on a higher frequency of case reports for upper airway cancer compared to bronchogenic carcinoma, marijuana smoking may have a more deleterious effect on the upper respiratory tract. However, this hypothesis remains speculative at best, pending confirmation by longitudinal studies.
