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We hypothesized that resistive breathing of moderate to high intensity might increase diaphragm oxidative stress, which could be partially attenuated by antioxidants. Our objective was to assess the levels of oxidative stress in the dog diaphragm after respiratory muscle training of a wide range of intensities and whether N-acetyl-cysteine (NAC) might act as an antioxidant. Twelve Beagle dogs were anesthetized with 1% propophol, tracheostomized, and subjected to continuous inspiratory resistive breathing (IRB) (2 h/day for 2 wk). They were further divided into two groups (n = 6): NAC group (oral NAC administration/24 h for 14 days) and control group (placebo). Diaphragm biopsies were obtained before (baseline biopsy) and after (contralateral hemidiaphragm) IRB and NAC vs. placebo treatment. Oxidative stress was evaluated in all diaphragm biopsies through determination of 3-nitrotyrosine immunoreactivity, protein carbonylation, hydroxynoneal protein adducts, Mn-SOD, and catalase, using immunoblotting and immunohistochemistry. Both protein tyrosine nitration and protein carbonylation were directly related to the amount of the respiratory loads, and NAC treatment abrogated this proportional rise in these two indexes of oxidative stress in response to increasing inspiratory loads. A post hoc analysis revealed that only the diaphragms of dogs subjected to high-intensity loads showed a significant increase in both protein tyrosine nitration and carbonylation, which were also significantly reduced by NAC treatment. These results suggest that high-intensity respiratory loading-induced oxidative stress may be neutralized by NAC treatment during IRB in the canine diaphragm.

Background: Tumor necrosis factor alpha (TNF-alpha) has been implicated in loss of muscle mass in chronic obstructive pulmonary disease and other consumptive processes. TNF-alpha production would be related to inflammation arising from pulmonary disease itself or, alternatively, from smoking, and would be carried to the muscle through the blood stream. However, it has also been suggested that TNF-alpha may be expressed directly in muscle tissue. Regardless the site of production of TNF-alpha, its relation to subsequent muscle damage is unclear., Objective: We studied the expression of TNF-alpha and an interleukin inhibitor of its production (IL-10) in the main respiratory muscles and a peripheral muscle in the dog., Method: Nine young, male Beagle dogs were included. From all animals we obtained a biopsy of the diaphragm (Dph) and external intercostal (ExtI) muscles and a leg muscle (internal vastus of the quadriceps, IntV). TNF-alpha and IL-10 gene expressions were measured through the analysis of messenger RNA levels, using reverse transcription and polymerase chain reaction. We also assessed sarcolemmal damage using intracellular fibronectin detection (immunohistochemistry)., Results: The expression of both cytokines showed wide interindividual variability. On the one hand, TNF-alpha (was very low in Dph and ExtI (0.02 0.03 and 0.05 0.06 a.u., respectively), but relatively high in the IntV (0.14 0.08 a.u.). IL-10 expression, on the other hand was low in the Dph (0.06 0.05 a.u.) and slightly higher in the ExtI (2.7 1.9 a.u., p < 0.01) and IntV (1.6 1.7 a.u.). Sarcolemmal damage was minimal in all three muscles and was related to TNF-alpha expression in the peripheral muscle (r = 0.682, p < 0.05)., Conclusions: 1) TNF-alpha and IL-10 appear to be constitutively expressed within the skeletal muscle in dogs. 2) Basal TNF-alpha expression is lower in respiratory muscles than in peripheral muscles. 3) The expression in the latter is related to membrane damage.

Background: The dog is one of the most widely used animals in studies of respiratory physiopathology, mainly because of its physiological characteristics. However, ethical and legal constraints are placed on the use of some species in our context., Objective: We studied the underlying structural features of respiratory and peripheral muscles in the beagle dog in order to suggest reference values for future studies., Method: Fourteen young beagles were selected. Samples were taken from the costal diaphragm (DFG), external intercostal (EI) and vastus medialis (VM) muscles. We analyzed fiber percentages and sizes (immunohistochemistry, using myosin heavy chain [MyHC (monoclonal antibodies), percentages and absolute number of MyHC isoforms (electrophoresis and ELISA), and level of membrane damage (immunohistochemistry, using anti-fibronectin monoclonal antibodies)., Results: In the EI muscle, type I fibers were larger (by 20%) than type II fibers. Fibers resistant to fatigue (type I) predominated greatly over fast contraction fibers (type II) in all three muscles analyzed (DFG 57% 11% vs. 45% 12%; EI 58% 5% vs. 43% 5%; and VM 70% 8% vs. 34% 7 %). Few hybrid fibers (co-expression of fast and slow MyHC) were found and their percentages were similar in all three muscles. The absolute expression of MyHC was greater in the VM than in the respiratory muscles, with a relative predominance of the MyHC I isoform in the DFG and VM muscles and a similar tendency in the EI muscle. Membrane damage was very slight in all three muscles., Conclusions: The phenotype characteristics of respiratory and peripheral muscles in the beagle correspond to what we would expect functionally for a breed initially selected for hunting, with minimal lesions under normal circumstances, a predominance of fibers and proteins that are resistant to fatigue, and larger fibers in the EI, a muscle that plays a role in respiration in dogs.

The diaphragm is the main inspiratory muscle. It is composed of two parts, the costal and crural, with both anatomical and functional differences. The general morphometric characteristics of the diaphragm have been described in various species but homogeneity throughout the muscle has not been adequately studied. The aim of this study was to evaluate the fiber phenotype of various parts of the diaphragm. The entire diaphragm muscles of five New Zealand rabbits were removed and each was divided into quarters. The specimens were processed for morphometry (hematoxyllineosin stains, NADH-TR and ATPase at pH levels of 4.2, 4.6 and 9.4). For each portion we measured percent and size of fibers, expressing the latter as minimum diameter (Dm), measured area (Ar) and calculated area (Ac). Left and right diaphragm hemispheres (20 portions examined) were similar for fiber percentages and sizes. For left and right halves, respectively 50 +/- 2 and 51 +/- 4% of fibers were type I; type I Dm measurements were 38 +/- 5 and 41 +/- 4 microns; type I Ar values were 1798 +/- 481 and 2030 +/- 390 micron 2; type I Ac values were 1181 +/- 360 and 1321 +/- 382 micron 2; type II Dm values were 46 +/- 4 and 46 +/- 5 microns; type II Ar values were 2466 +/- 388 micron 2 and 2539 +/- 456 micron 2; type II Ac data were 1642 +/- 255 and 1655 +/- 382 micron 2. We likewise found no differences between costal and crural portions of the muscle (n = 20). For costal and crural portions, respectively, 50 +/- 3 and 50 +/- 2% of fibers were type I; type I Dm sizes were 39 +/- 5 and 40 +/- 4 microns; type I Ar measurements were 1859 +/- 521 and 1964 +/- 365 micron 2; type I Ac figures were 1231 +/- 317 and 1266 +/- 288 micron 2; type II Dm were 47 +/- 4 and 44 +/- 3 microns; type II Ar were 2563 +/- 481 and 2430 +/- 331 micron 2; type II Ac were 1729 +/- 373 and 1557 +/- 212 micron 2. Type II fibers, however, were somewhat larger than type I fibers in all portions (p = 0.001). New Zealand rabbit diaphragm muscle has similar percentages of slow and rapid contraction fibers. The size is not different from that observed in other species of mammals of similar size. Fiber type proportions are similar throughout the muscle, with more type II fibers present in all areas. The morphometric characters, therefore, suggest an homogeneous throughout the diaphragm, suggesting homogeneous response of the muscle to usual loads, and also suggesting the possibility of proposing longitudinal morphometric studies using this species as a model.

We report our 3-years experience with video-thoracoscopy for pneumothorax. Forty-six endoscopies (34 men, 12 women; mean age 27 +/- 9 years) were performed. Patients were under general anesthesia and intubation was selective. The conventional approach was used, with 3 incisions through which the camera and endoscopic instruments were inserted. Results were good in 39 (84.7%) patients. Pneumothorax recurred in 4 (8.7%) patients during the 3 years of follow-up. Thoracotomy was performed in 3 patients, because of lack of lung expansion in 1, persistent leak in another and encapsulated empyema in the third. Mean hospital stay after surgery was 7.3 days. Video-thoracoscopy can be considered a good therapeutic alternative to thoracotomy in the surgical treatment of patients with pneumothorax.

We describe a 39-year-old woman who suffered rupture of the left auricula as a result of a non-penetrating chest wound received in a traffic accident. Rupture of the heart chambers after trauma is not infrequent, but survival is extremely rare. The patient was released from care and has suffered no subsequent complications.