Preconditioning as a Possible Protective Mechanism in the Spinal Cord Ischemia

The present study deals with the problem of spinal cord protection. The aim of this study was to simulate conditions during surgery on aortic aneurysm and to consider their possible utilisation in clinical practice. Wistar albino rats of both sexes were used in the experiment. Surgery was performed on the thoracic part of aorta. The closure of aorta in duration of 12 min caused a neurological deficit in 81% of rats, 14 min of ischemia paralysed 90% of animals. Preconditioning with 3-min ischemia following 30 min recirculation improved the neurological score in the group with 12 min of ischemia after 48 h, in which only 27% of rats were paralysed. The same preconditioning was performed in the group of animals with 14 min of ischemia, and as a consequence, 33% of rats were paralysed in that group. Protection of the spinal cord during ischemia can be achieved by preconditioning. Thus the method of preconditioning appears to be a prospective technique for the improvement of the devastating neurological deficit after surgery on the aorta and has provided optimism that additional therapies will be possible in the future

Bioaccumulation and toxicity of selenium compounds in the green alga Scenedesmus quadricauda

<p>Abstract</p> <p>Background</p> <p>Selenium is a trace element performing important biological functions in many organisms including humans. It usually affects organisms in a strictly dosage-dependent manner being essential at low and toxic at higher concentrations. The impact of selenium on mammalian and land plant cells has been quite extensively studied. Information about algal cells is rare despite of the fact that they could produce selenium enriched biomass for biotechnology purposes.</p> <p>Results</p> <p>We studied the impact of selenium compounds on the green chlorococcal alga <it>Scenedesmus quadricauda</it>. Both the dose and chemical forms of Se were critical factors in the cellular response. Se toxicity increased in cultures grown under sulfur deficient conditions. We selected three strains of <it>Scenedesmus quadricauda </it>specifically resistant to high concentrations of inorganic selenium added as selenite (Na₂SeO₃) – strain SeIV, selenate (Na₂SeO₄) – strain SeVI or both – strain SeIV+VI. The total amount of Se and selenomethionine in biomass increased with increasing concentration of Se in the culturing media. The selenomethionine made up 30–40% of the total Se in biomass. In both the wild type and Se-resistant strains, the activity of thioredoxin reductase, increased rapidly in the presence of the form of selenium for which the given algal strain was not resistant.</p> <p>Conclusion</p> <p>The selenium effect on the green alga <it>Scenedesmus quadricauda </it>was not only dose dependent, but the chemical form of the element was also crucial. With sulfur deficiency, the selenium toxicity increases, indicating interference of Se with sulfur metabolism. The amount of selenium and SeMet in algal biomass was dependent on both the type of compound and its dose. The activity of thioredoxin reductase was affected by selenium treatment in dose-dependent and toxic-dependent manner. The findings implied that the increase in TR activity in algal cells was a stress response to selenium cytotoxicity. Our study provides a new insight into the impact of selenium on green algae, especially with regard to its toxicity and bioaccumulation.</p

Densitometric patterns of NADPH diaphorase staining in the spinal cord of dog

Mar ala, M., Densitometric patterns of NADPH diaphorase staining in the spinal cord of dog. Biologia, Bratislava, 56: 685-693, 2001; ISSN 0006-3088 (Biologia). ISSN 1335-6399 (Biologia. Section Cellular and Molecular Biology). Segmental and laminar distribution of NADPHd activity was studied in the normal spinal cord of the dog and basic densitometric patterns of somatic, fiber-like and punctuate, non-somatic NADPHd staining were described in the gray and white matter. Prominent NADPHd activity was noted in the superficial and deep dorsal horn, pericentral region, intermediolateral cell column, Lissauer&apos;s tract and in the vertical and horizontal limbs of the medial longitudinal bundle of the ventral column in the cervical and upper thoracic segments. Key words: densitometry, NADPH diaphorase, spinal cord, dog. Introduction The use of nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry alone or combined with the nitric oxide synthase immunoreactivity (NOS-IR) allowed for a morphologically distinct and topographically precise localization of small neuronal pools synthesizing, releasing and transporting NOS, an enzyme responsible for nitric oxide (NO) synthesis. The discrete loci, nuclei or solitary NOS-IR neurons have been identified not only in the cortex, brain stem and spinal cord, but also in the peripheral nervous system (Vincent &amp; Johanson, 1983; Immunocytochemistry of the neuronal nitric oxide synthase (nNOS) showed that the occurrence of this enzyme is almost completely homotopic with the localization of neurons stained for NADPHd In the present study an attempt was made to specify the differences of somatic, fiber-like, and punctuate NADPHd staining in the gray and white matter of the spinal cord in the normal dog, including different segments and layers using the densitometric analysis. Densitometric patterns of NADPHd positivity in the undamaged spinal cord may be helpful in experimental studies aimed at a causal interpretation of changes affecting the NOS-containing neuronal pools in various experimental and pathologic conditions. Material and methods Tissue sampling, sectioning, examination of sections and the performance of the densitometric analysis Adult dogs (n = 6) of both sexes weighing 12-18 kg were used in this study. The animals were deeply anesthetized with pentobarbital (50 mg/kg, i.v.) and perfused transcardially with saline followed by freshly prepared 4% paraformaldehyde +0.1% glutaraldehyde buffered with 1M sodium phosphate, pH = 7.4. Following perfusion fixation, the spinal cords were carefully dissected out and stored in toto in the same fixative for 3-4 hours. After postfixation, the spinal cord was divided into cervical, thoracic, lumbar, sacral and coccygeal segments, and each segment was then secondarily divided into three small blocks comprising the upper, middle, and lower segmental levels, respectively. Specimens were then cryoprotected in an ascending concentration of sucrose (15-30%) with the same phosphate buffer and stored overnight at 4 • C. Frozen transverse sections (50 µm thick) were cut from all segments studied and processed for NADPH-d activity by using a modified histochemical procedure The densitometric analysis was performed using transverse sections stained for NADPHd histochemistry. Precise loci identified in the gray and white matter on transverse sections were used for the assessment of the densitometric patterns in both compartments of the spinal cor