Nephrotoxic effect of the specific brain serotonin depletor para-chlorophenylalanine

Brain serotonin depletion induced by peripheral parachlorophenylalanine (pCPA) is frequently used to evaluate the role of the central serotoninergic system in the regulation of a number of physiological functions, including the secretion of renin by the kidney. We found that due to the treatments applied in the protocol used for the investigation of pCPA effect on renin and vasopressin secretion in rats (300 mg/kg i.p. 64 and 40 h before sacrifice) renal injury was induced as well. Typical changes indicating acute renal failure were observed--an initial polyuria, natriuresis and body mass loss, succeeded by oliguria, decreased glomerular filtration rate, and salt and creatinine retention. Morphological changes in the glomeruli included a thickening of the basal membranes, a confluence and a reduced number of podocyte pedicles. A slight to moderate granular degeneration was observed in epithelial cells of the proximal convoluted tubule, combined with mitochondrial changes--an increase in number, matrix disorganization, and myelin degeneration. In conclusion, the renal function changes after i.p. pCPA may be due not to brain serotonin depletion-alone, but also to nephrotoxic effect.     

Taxonomic spectrum of pathogens of mixed infections in oncology patients and principles of their antibacterial therapy

Mixed infections were observed in oncological patients irrespective of the tumor or infectious process localization. 25-30 per cent of the pathological materials from such patients were contaminated with bacterial associations. The number of the associates ranged from 2 to 5 depending on the pathological material tested. Therapy of infectious complications due to pathogen associations should stem from analysis of many factors, i.e. properties of the isolated or likely pathogens, individual characteristics of the patients, compatibility of the drugs used and their pharmacokinetic features.     

Establishment of polarized endocytosis in differentiable intestinal HT29-18 subclones

Subclones of the HT29-18 clone, derived from a human adenocarcinoma, are able to acquire an enterocyte-like phenotype depending on the culture conditions. To investigate fluid-phase and receptor-mediated endocytosis in the polarized subclone HT29-18-C1, we established culture conditions that allowed cell growth on permeable supports. HT29-18-C1 monolayers had an electrical resistance of 43 ohms.cm2 and developed a transepithelial potential of about 2 mV. Transferrin receptors were uniformly distributed on the entire cell surface of undifferentiated HT29-18 cells but were located on the basolateral membrane of differentiated cells. Transferrin had a high affinity (Kd = 2.5 x 10(-9) M) for its receptor independent of the state of differentiation. The number of transferrin receptors and the mRNA amounts encoding them were comparable in the undifferentiated and differentiated HT29-18 cells. Transferrin was quickly internalized and recycled back to the cell surface of undifferentiated HT29-18 cells. The same phenomenon also occurred in differentiated HT29-18 cells, but the receptors were limited to the basolateral membrane. In the presence of ammonium chloride, the process was slower but remained polarized. Fluid-phase uptake was also investigated with horseradish peroxidase (HRP) in differentiated HT29-18 C1 cells. HRP that was internalized in 1 hour from a given membrane domain preferentially recycled back to the same membrane domain. No significant accumulation of the enzyme in the late endosomes and lysosomes of the differentiated HT29-18-C1 cells was observed.     

Rapid colorimetric detection of in vitro amplified DNA sequences

A colorimetric assay to detect immobilized amplified nucleic acids has been designed. This approach provides a rapid assay, suitable for clinical diagnosis, to analyze DNA sequences amplified by the polymerase chain reaction. The specific DNA sequences are captured on a solid support by the use of a recombinant fusion protein consisting of the Escherichia coli lac repressor and staphylococcal protein A. The biotin streptavidin system is used to detect the immobilized material. Positive samples can be analyzed by direct solid-phase sequencing. Here, we show that this nonradioactive concept can be used for analysis of Staphylococci and Streptococci and for specific detection of the protozoa Plasmodium falciparum in clinical samples.     

Application of Deuterated A-Tocopherols to the Biokinetics and Bioavailability of Vitamin E

-Tocopherol, a superior chain-breaking, peroxyl radical-trapping antioxidant and the most active component of vitamin E, is elevated in liver tumor cells, contributing to their greater resistance towards lipid peroxidation compared to cells from normal tissues. Also, in regenerating rat liver the level of vitamin E has been found to fluctuate in phase with the rate of cell division. In order to study the biokinetcis and mechanisms of the distribution of vitamin E in organs and within tissues of animals, deuterated forms of -tocopherol have been synthesized and their uptake into blood and tissues has been measured by gas chromatography-mass spectrometry. Measurement of the competitive uptake from a mixture of the RRR-and SRR--tocopherol stereoisomers labelled with different amounts of deuterium shows that the liver exerts a strong preference for secretion of the natural (RRR) stereoisomer into the plasma. It is suggested that a tocopherol-binding protein plays a key role in this process.     

Ventilatory control during exercise in calves with artificial hearts

To determine the role of cardiac reflexes in mediating exercise hyperpnea, we investigated ventilatory responses to treadmill exercise in seven calves with artificial hearts and seven controls. In both groups, the ventilatory responses were adequate for the metabolic demands of the exercise; this resulted in regulation of arterial PCO2 and pH despite the absence of cardiac output increase in the implanted group. In this group, there was a small but significant reduction of arterial PO2 by 4 +/- 3 Torr and a rise of blood lactate by 1.1 +/- 1 mmol/l. When cardiac output was experimentally increased in the implanted calves to a level commensurate with that spontaneously occurring in the control calves, ventilation was not affected. However, experimental reductions of cardiac output led to an immediate augmentation of exercise hyperpnea by 4.56 +/- 4.3 l/min and a further significant lactate increase of 1.2 +/- 1.22 mmol/l that was associated with a significant decrease in the exercise O2 consumption (0.32 +/- 0.13 l/min). These observations indicate that neither cardiac nor hemodynamic effects of increased cardiac output constitute an obligatory cause of exercise hyperpnea in the calf.     

Identification and Determination of 3,4-Dihydroxyphenylacetaldehyde, the Dopamine Metabolite, in In Vivo Dialysate from Rat Striatum

Abstract: 3,4-Dihydroxyphenylacetic acid (DOPAC) is commonly considered to be the main dopamine (DA) metabolite produced by monoamine oxidase (MAO); however, the initial product of DA oxidation is 3,4-dihydroxyphenylacetaldehyde (DOPALD). Owing to technical difficulties in detecting DOPALD from a biological matrix, no studies have so far been performed to measure brain levels of this aldehyde in vivo. In this work, using transstriatal microdialysis in freely moving rats, we identified DOPALD by HPLC coupled to a coulometric detector. In chromatograms obtained from microdialysis samples, DOPALD appeared as a peak with a retention time coincident with that of the standards obtained via enzymatic and chemical synthesis. On the other hand, DOPALD was undetectable ex vivo from rat striatal homogenates. This discrepancy is probably due to the preferential extraneuronal localization together with the high reactivity of the aldehyde, which is rapidly removed by the dialysis probe, whereas the ex vivo procedure allows its condensation and enzymatic conversion. Measurement of DOPALD levels as a routine procedure might represent a reliable tool to evaluate DA oxidative metabolism directly, in vivo. Moreover, parallel detection of DOPALD and DOPAC levels in brain dialysate may make it possible to distinguish between the activity of MAO and aldehyde dehydrogenase. DOPALD, like many endogenous aldehydes, has been shown to be toxic to the cell in which it is formed. Therefore, in vivo measurement of DOPALD levels could highlight new aspects in the molecular mechanisms underlying both acute neurological insults and neurodegenerative diseases.     

Molecular evidence of a lignin peroxidase H8 homologue inFusarium oxysporum

We describe an evidence for the existence of a ligninase isoenzyme H8 in the deuteromyceteFusarium oxysporum on the genomic as well as on the RNA level.     

Growth interactions betweenPleurotus tuber-regium andSclerotium rolfsii

Sclerotium rolfsii, a destructive soil pathogen common in tropical soils, was found to cause stipe rot of the fruit bodies ofPleurotus tuber-regium. The rot occurs only when the pathogen is inoculated into the soil before seeding and before primordial emergence. It caused 100% inhibition of primordia and sporophore formation when the soil was inoculated before seeding and highly reduced yield when the soil was inoculated with the pathogen just before primordial emergence. However, no fruit body rot occurred on the mushroom when the soil was inoculated with the pathogen after primordial emergence from the soil.