Identification of a voltage-gated potassium channel in gerbil hippocampal mitochondria

Transient cerebral ischemia is known to induce endogenous mechanisms that can prevent or delay neuronal injury, such as the activation of mitochondrial potassium channels. However, the molecular mechanism of this effect remains unclear. In this study, the single-channel activity was measured using the patch-clamp technique of the mitoplasts isolated from gerbil hippocampus. In 70% of all patches, a potassium-selective current with the properties of a voltage-gated Kv-type potassium channel was recorded with mean conductance 109 ± 6 pS in a symmetrical solution. The channel was blocked at negative voltages and irreversibly by margatoxin, a specific Kv1.3 channel inhibitor. The ATP/Mg²⁺ complex and Ca²⁺ ions had no effect on channel activity. Additionally, agitoxin-2, a potent inhibitor of voltage-gated potassium channels, had no effect on mitochondrial channel activity. This observation suggests that in contrast to surface membrane channels, the mitochondrial voltage-gated potassium channel could have a different molecular structure with no affinity to agitoxin-2. Western blots of gerbil hippocampal mitochondria and immunohistochemistry on gerbil brain sections confirmed the expression of the Kv1.3 protein in mitochondria. Our findings indicate that gerbil brain mitochondria contain a voltage-gated potassium channel that can influence the function of mitochondria in physiological and pathological conditions and that has properties similar to the surface membrane Kv1.3 channel.     

Effect of dilute acid pretreatment on the saccharification and fermentation of rye straw

This research shows the effect of dilute acid pretreatment with various sulfuric acid concentrations (0.5–2.0% [wt/vol]) on enzymatic saccharification and fermentation yield of rye straw. After pretreatment, solids of rye straw were suspended in Na citrate buffer or post-pretreatment liquids (prehydrolysates) containing sugars liberated after hemicellulose hydrolysis. Saccharification was conducted using enzymes dosage of 15 or 25 FPU/g cellulose. Cellulose saccharification rate after rye straw pretreatment was enhanced by performing enzymatic hydrolysis in sodium citrate buffer in comparison with hemicellulose prehydrolysate. The maximum cellulose saccharification rate (69%) was reached in sodium citrate buffer (biomass pretreated with 2.0% [wt/vol] H₂SO₄). Lignocellulosic complex of rye straw after pretreatment was subjected to separate hydrolysis and fermentation (SHF) or separate hydrolysis and co-fermentation (SHCF). The SHF processes conducted in the sodium citrate buffer using monoculture of Saccharomyces cerevisiae (Ethanol Red) were more efficient compared to hemicellulose prehydrolysate in respect with ethanol yields. Maximum fermentation efficiency of SHF processes obtained after rye straw pretreatment at 1.5% [wt/vol] H₂SO₄ and saccharification using enzymes dosage of 25 FPU/g in sodium citrate buffer, achieving 40.6% of theoretical yield. However, SHCF process using cocultures of pentose-fermenting yeast, after pretreatment of raw material at 1.5% [wt/vol] H₂SO₄ and hydrolysis using enzymes dosage of 25 FPU/g, resulted in the highest ethanol yield among studied methods, achieving 9.4 g/L of ethanol, corresponding to 55% of theoretical yield.     

Differential effects of morphine and naltrexone on the in vitro LH secretion from male and female carp pituitary gland

The in vitro effects of morphine (10(-10), 10(-8), 10(-6) or 10(-5) M) or/and naltrexone (10(-6) or 10(-8) M) on LH release from male and female carp (Cyprinus carpio L.) dispersed pituitary cells (obtained from fish at the time of late gonad recrudescence) were investigated. Morphine alone at the lowest tested concentration (10(-10) M) increased LH secretion from the cells of males. On the contrary, in female cell incubations the highest concentrations of morphine (10(-6) or 10(-5) M) significantly lowered LH levels. Naltrexone alone (at both tested concentrations) had no influence on LH secretion, neither in males nor in females. However in the incubations of female cells it antagonised the influence of morphine at 10(-10) or 10(-8) M. In male cell incubations naltrexone abolished the stimulatory action of morphine at 10(-10) M. The results suggest that in the in vitro culture of carp pituitary cells LH secretion is modulated by the opioids which affect the release of this gonadotropin through the typical opioid receptors and that the mu type of these receptors is involved in this process. The effects of opioid agonist and antagonist depend on the stage of gonadal maturity and the sex of fish i.e. the actual level of sex steroids.     

Does the inhibition of c-myc expression mediate the anti-tumor activity of PPAR's ligands in prostate cancer cell lines?

Peroxisome proliferator-activated receptor gamma (PPARgamma) ligands seem to induce anticancer effects on prostate cancer cells, but the mechanism is not clear. The effect of PPARgamma ligands omega-6 fatty acids and ciglitazone (2-15 microM)--on proliferation, and apoptosis of LNCaP, PC-3, DU145, CA-K and BPH-K cells was studied. PPARgamma ligands led to: (1) reduction of proliferation (20-50%) of all the studied cell lines, (2) stimulation of differentiation of prostate cancer cells through an increased expression (1.5-3-fold: LNCaP, DU145, BPH-K) or reexpression (PC-3, CA-K) of E-cadherin with parallel inhibition of N-cadherin expression (PC-3, CA-K) and (3) down-regulation (1-2-fold) of beta-catenin and c-myc expression. The selective PPARgamma antagonist GW9662 abolished the effect of those ligands on prostate cancer cells. These results suggest that inhibition of beta-catenin and in effect c-myc expression through activation of PPARgamma may help prostate cancer cells to restore several characteristics of normal prostate cells phenotype.     

Assessment of intraorbital structure volume using a numerical segmentation image technique (NSI): the fatty tissue and the eyeball

INTRODUCTION: Measurement of the degree of exophthalmos is one of the main methods used in the assessment of pathological processes that occur in the orbital space and is widely used. However, this only provides initial information about the volume relations between the intraorbital structures. The aims of our work were as follows: to draw up a new computer application, namely the numerical segmentation image (NSI) technique, for the automatic calculation of the volume of the intraorbital structures on the basis of magnetic resonance imaging (MRI) images, to determine its usefulness in the segmentation of fatty tissue and the eyeball and to estimate their volume in relation to the degree of exophthalmos. MATERIAL AND METHODS: A total of 45 patients (90 orbits) were included in the study. All the patients underwent MRI examination of the orbits by a 1.5 T scanner using a head coil. The degree of exophthalmos was determined clinically and radiologically in relation to the interzygomatic line. Quantitative assessment of the eyeball and fatty tissue was made using an NSI application. RESULTS: The influence of fatty tissue volume on the degree of exophthalmos was determined as being statistically significant (r = 0.367, p = 0.000374) but was smaller in comparison with the relationship between total eye muscle volume and degree of exophthalmos; eyeball volume was found to have the least influence (r = 0.344, p = 0.000374). Two eyeballs of significantly smaller volume were found in the group of 90 orbits analysed. CONCLUSIONS: The NSI technique is a clinically useful application, providing objective data calculated individually for each orbit. A credible protocol for estimating the degree of exophthalmos on the basis of the NSI technique should include the eye muscle volume, fatty tissue volume and, in cases where eyeball pathologies coexist, the eyeball volume as well.     

Diagnostic difficulties in adrenal incidentaloma--analysis of 125 cases

INTRODUCTION: Therapeutic approach to incidentaloma, in spite of existing algorithms, is not always obvious due to diagnostic difficulties. The aim of the study was to assess the validity of the initial diagnoses of incidentaloma which determined the qualification for the operation. MATERIAL AND METHODS: 125 patients hospitalised in the Endocrinology Dept. of the Medical University of Bialystok in the years 2003-2005 and in the Endocrinology dept. of Voivodeship Hospital of Bialystok. The patients were clinically and hormonally examined (metanephrines in daily urine collection, daily cortisol rhythm, short dexamethasone test, aldosterone, and renin plasma activity, Na, K levels in the serum) as well as computer tomography of the adrenal glands were performed. RESULTS: 42 patients were qualified for adrenalectomy. Adenoma was confirmed in 25 patients (in 7 subclinical Cushing syndrome was diagnosed, in 2 Conn disease, in 16 inactive changes), phaeochromocytoma in 6 patients, cysts in 3, lipoma in 2, carcinoma in one, in 4 patients metastases (in 2 of kidney carcinoma, in 1 of malignant melanoma and in 1 of planocellular carcinoma) and in one oncocytoma. Metanephrines urine measurements showed 33% of false positive results. CONCLUSIONS: Qualification for adrenalectomy requires an assessment of tumor's enlargement, its tissue density, morphology and growth dynamics. To reduce the percentage of false positive results of metanephrine measurement there is to eliminate an influence of some drugs, victuals, beverages and nicotine and eventually to carry out additional tests. The decision as to proceeding with adrenal incidentaloma should be individualized based on clinical symptoms, hormonal tests and tumor morphology.     

Pronuclear scoring as a predictor of embryo quality in in vitro fertilization program

Many strategies have been proposed for the selection of viable embryos for transfer in human assisted reproduction. These have included morphological scoring criteria for 20, 28, 44 and 68 h after insemination. The embryo selection is based on morphology, degree of fragmentation and development to the 8-cell. All have shown some correlation with implantation. However, the overall success of these methods is still limited, with over 50% of all transferred embryos failing to implant. Pronuclear zygote morphology has gained much attention recently due to its positive value in predicting implantation and pregnancy. This prospective study involved 178 conventional IVF patients only. The key aspects of pronuclear scoring and namely the presence of a cytoplasmic halo were related to day 3 of development and morphology in a retrospective study. The Z-score and the presence/absence of a halo had significant effect on the rate of development on day 3 embryo. Low Z-score result in slow development and poor morphology. The absence of a halo also resulted in slow and poor development, low morphology, increased fragmentation.     

Identification and structural characterization of heme binding in a novel dye-decolorizing peroxidase, TyrA

TyrA is a member of the dye-decolorizing peroxidase (DyP) family, a new family of heme-dependent peroxidase recently identified in fungi and bacteria. Here, we report the crystal structure of TyrA in complex with iron protoporphyrin (IX) at 2.3 A. TyrA is a dimer, with each monomer exhibiting a two-domain, alpha/beta ferredoxin-like fold. Both domains contribute to the heme-binding site. Co-crystallization in the presence of an excess of iron protoporphyrin (IX) chloride allowed for the unambiguous location of the active site and the specific residues involved in heme binding. The structure reveals a Fe-His-Asp triad essential for heme positioning, as well as a novel conformation of one of the heme propionate moieties compared to plant peroxidases. Structural comparison to the canonical DyP family member, DyP from Thanatephorus cucumeris (Dec 1), demonstrates conservation of this novel heme conformation, as well as residues important for heme binding. Structural comparisons with representative members from all classes of the plant, bacterial, and fungal peroxidase superfamily demonstrate that TyrA, and by extension the DyP family, adopts a fold different from all other structurally characterized heme peroxidases. We propose that a new superfamily be added to the peroxidase classification scheme to encompass the DyP family of heme peroxidases.