Functional stages in the interrenal cells of Rana perezi (Anura: Ranidae).

The electron density of the lipid droplets and mitochondrial matrix of the interrenal cells of Rana perezi differs during the year. This makes it possible to characterize the different stages of interrenal cell activity. A droplet/mitochondria index, based on their relative size, may provide an indicator of cellular activity.     

Screening for thermostability and electrophoretic red blood cell sorbitol dehydrogenase (E.C.1.1.1.14) variants

A screening for both thermostability and electrophoretic red blood cell sorbitol dehydrogenase (RBC-SORD) variants in blood donors was performed. SORD activity in standard conditions (unheated samples) in 274 individuals was 198 +/- 38.6 mIU/g Hb. The ratio of enzymatic activity after heating (H) to the activity in controls (C) before heating (H/C ratio) was 0.39 +/- 0.10. H/C ratios minor than 0.1 in 3 out of 274 blood donors and higher than 0.9 in 1 were observed. In 208 individuals, four electrophoretic phenotypes were observed: I) Three bands, named a, b and c, with cathodic mobility in 163 individuals (78.36%); II) Two bands a and c in 25 individuals (12.02%); III) Two bands b and c in 14 (6.73%); and IV) One band, c in 6 (2.88%). Studies carried out to characterize the three bands suggest that they are isozymes of the same locus with the observation of an interchange of the bands as a normal phenomena.     

Effect of growth temperature on complement-mediated killing of mesophilic Aeromonas spp. serotype O:34

Abstract Mesophilic Aeromonas spp. strains (serotype O:34) showed sensitivity to complement-mediated killing when they were cultivated at 37°C (serum-sensitive) but not when they were cultivated at 20°C (serum-resistant). These strains produced smooth lipopolysaccharide when they were grown at 20°C and rough lipolysaccharide when cultivated at 37°C. The reason for the resistance to complement-mediated killing could be that C3b is rapidly degraded (possibly because it is bound far from the cell membrane), consequently the lytic complex (C5b-9) is not formed.     

Respiratory loading intensity and diaphragm oxidative stress: N-acetyl-cysteine effects.

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.