Oxygen consumption during septic shock. Effects of inotropic drugs

Septic shock may be defined as a clinical entity wherein a patient has an inadequate peripheral metabolism in the presence of circulating bacteria. The demands for metabolic requirements of the tissues and hence for oxygen transport to these tissues are then markedly high. The average response to increased metabolism in such patients is a percentage increase in cardiac output that is comparable to the percentage increase in oxygen consumption while oxygen extraction rate does not change or even decreases in severe or/and advanced septic shock. This emphasizes the high priority placed by the body on the ability to increase blood flow from the heart in the presence of increased metabolic demands due to sepsis. Concerning the myocardium, oxygen consumption is low in hyper- and hypodynamic states of septic shock, probably and partially due to marked arterial vasodilatation. However, in hypodynamic states, the lower value of perfusion pressure may account for a decrease in myocardial oxygen supply, especially in subendocardial areas and may be responsible for myocardial ischaemia, more especially as myocardial oxygen extraction as well as systemic oxygen extraction is impaired. The goal of therapeutics is to improve oxygen availability through: (1) maintenance of haemoglobin levels and (2) increases in stroke volume using inotropic drugs since these drugs may produce a rise in myocardial oxygen supply higher than their drug-induced increase in oxygen requirements in hypodynamic states of septic shock.     

Iron and iron/manganese ratio in forage from Icelandic sheep farms: relation to scrapie

This study was undertaken in order to examine whether any connection existed between the amounts of iron in forage and the sporadic occurrence of scrapie observed in certain parts of Iceland. As iron and manganese are considered antagonistic in plants, calculation of the Fe/Mn ratios was also included by using results from Mn determination earlier performed in the same samples. Forage samples (n = 170) from the summer harvests of 2001–2003, were collected from 47 farms for iron and manganese analysis. The farms were divided into four categories: 1. Scrapie-free farms in scrapie-free areas (n = 9); 2. Scrapie-free farms in scrapie-afflicted areas (n = 17); 3. Scrapie-prone farms (earlier scrapie-afflicted, restocked farms) (n = 12); 4. Scrapie-afflicted farms (n = 9). Farms in categories 1 and 2 are collectively referred to as scrapie-free farms. The mean iron concentration in forage samples from scrapie-afflicted farms was significantly higher than in forage samples from farms in the other scrapie categories (P = 0.001). The mean Fe/Mn ratio in forage from scrapie-afflicted farms was significantly higher than in forage from scrapie-free and scrapie-prone farms (P < 0.001). The results indicated relative dominance of iron over manganese in forage from scrapie-afflicted farms as compared to farms in the other categories. Thus thorough knowledge of iron, along with manganese, in soil and vegetation on sheep farms could be a pivot in studies on sporadic scrapie.     

Oestrogen and essential fatty acid supplementation corrects bone loss due to ovariectomy in the female Sprague Dawley rat

Essential fatty acid deficient animals develop osteoporosis. Eicosapentaenoic acid and gamma-linoleic acid have been reported to have positive effects on bone metabolism in both the growing male rat and the ovariectomized (OVX) female rat. These effects have been further investigated using a novel gamma-linolenic/eicosapentaenoic acid diester together with an oestrogen implant in the ovariectomized, female Sprague Dawley rat. Rats were sham-operated or ovariectomized at age 11 weeks. Two groups of OVX rats received an oestrogen implant at ovariectomy. Animals received fatty acids, linoleic acid (control) or a diester with gamma-linolenic acid and eicosapentaenoic acid as part of a semi-synthetic diet. Bone calcium content and excretion of deoxypyridinolines as marker of bone degradation were measured at 14 weeks. Oestrogen, as well as diester alone, increased calcium/femur to sham levels. Oestrogen plus diester potentiated the effect of oestrogen on bone calcium (P < 0.05 vs OVX). At the same time, oestrogen alone and the combination of oestrogen plus diester significantly reduced (P < 0.05 vs OVX) urinary deoxypyridinoline and hydroxyproline excretion. Again, the diester potentiated the effect of oestrogen. The effects of the diester alone, together with the potentiated effects of oestrogen by the essential fatty acids on osteoporosis, are novel findings.     

Quinone analogues regulate mitochondrial substrate competitive oxidation

Quinone derivatives are among the rare compounds successfully used as therapeutic reagents to fight mitochondrial diseases. However, their beneficial effect appears to depend on their side chain which presumably governs their interaction with the respiratory chain. The effect of four quinone derivatives was comparatively studied on NADH- and succinate-competitive oxidation by a sub-mitochondrial fraction. Under our experimental conditions, the less hydrophobic derivatives (menadione, duroquinone) poorly affected electron flow from either NADH or succinate to oxygen, yet readily diverting electrons from isolated complex I. This latter effect was abolished by succinate addition. More hydrophobic derivatives (idebenone, decylubiquinone) stimulated oxygen uptake from succinate. But while NADH oxidation was slightly inhibited by idebenone, it was somewhat increased by decylubiquinone. As a result, idebenone strongly favoured succinate over NADH oxidation. This study therefore suggests that any therapeutic use of quinone analogues should take into account their specific effect on each respiratory chain dehydrogenase.     

Scanning electron microscopy and gramicidin patch clamp recordings of microvillous receptor neurons dissociated from the rat vomeronasal organ

Vomeronasal organs from female rats were dissociated and isolated microvillous receptor neurons were studied. The isolated receptor neurons kept the typical bipolar shape which they have in situ as observed by scanning electron microscopy. We applied the perforated patch-clamp technique using the cation-selective ionophore gramicidin on freshly isolated and well differentiated receptor neurons. The mean resting potential was -58+/-14 mV (n=39). The contribution of the sodium pump current to the resting potential was demonstrated by lowering the K+ concentration in the bath or by application of 100 microM dihydro-ouabain. The input resistance was in the range of 1-6 GOmega and depolarizing current pulses of a few pA were sufficient to trigger overshooting action potentials. In voltage clamp conditions a fast transient sodium inward current and a sustained outward potassium current were activated by membrane depolarization. These observations indicate that freshly isolated vomeronasal receptor neurons of rats can be recorded, using gramicidin, with little modification of the intracellular content. Their electrophysiological properties are very similar to those observed in situ. Four out of eight female vomeronasal receptor cells were depolarized by diluted rat male urine.      

Degradation of different polystyrene/thermoplastic starch blends buried in soil

Blends of PS and TPS were prepared using two different plasticizers: glycerol or buriti oil by solvent casting technique. PS/TPS blends were submitted to degradation by soil burial tests in perforated boxes for 6 months and later analyzed by TG and CPMAS ¹³C NMR. After degradation, blends with glycerol presented less stages of thermal degradation and NMR signals of minor intensity compared to the original blends. The presence of TPS at contents of 50% or greater improved the degradation of the blends. After 6 months, PS/TPS blends with buriti oil presented only one thermal degradation stage with a significant increase in mass loss. Moreover, all absorptions related to starch disappeared in NMR spectra after soil buried test, probably due to the consumption of starch by microorganisms. These results revealed that PS’s degradability can be improved when TPS plasticized with buriti oil is added to it.     

Quantification of Tumor Vessels in Glioblastoma Patients Using Time-of-Flight Angiography at 7 Tesla: A Feasibility Study

Purpose

To analyze if tumor vessels can be visualized, segmented and quantified in glioblastoma patients with time of flight (ToF) angiography at 7 Tesla and multiscale vessel enhancement filtering.

Materials and Methods

Twelve patients with newly diagnosed glioblastoma were examined with ToF angiography (TR = 15 ms, TE = 4.8 ms, flip angle = 15°, FOV = 160×210 mm², voxel size: 0.31×0.31×0.40 mm³) on a whole-body 7 T MR system. A volume of interest (VOI) was placed within the border of the contrast enhancing part on T1-weighted images of the glioblastoma and a reference VOI was placed in the non-affected contralateral white matter. Automated segmentation and quantification of vessels within the two VOIs was achieved using multiscale vessel enhancement filtering in ImageJ.

Results

Tumor vessels were clearly visible in all patients. When comparing tumor and the reference VOI, total vessel surface (45.3±13.9 mm² vs. 29.0±21.0 mm² (p<0.035)) and number of branches (3.5±1.8 vs. 1.0±0.6 (p<0.001) per cubic centimeter were significantly higher, while mean vessel branch length was significantly lower (3.8±1.5 mm vs 7.2±2.8 mm (p<0.001)) in the tumor.

Discussion

ToF angiography at 7-Tesla MRI enables characterization and quantification of the internal vascular morphology of glioblastoma and may be used for the evaluation of therapy response within future studies.     

The presence of macrophytes changes the beta diversity of Ephemeroptera,Plecoptera, and Trichoptera (EPT) assemblages in Cerrado streams in Northeastern Brazil

Limnology - In-stream conditions can affect the distribution of the Ephemeroptera, Plecoptera, and Trichoptera orders (EPT) because they require specific food resources and good quality water....     

Purification and characterization of a pectin lyase produced by Pseudomonas fluorescens W51.

A pectin lyase (PNL; EC 4.2.2.10) was isolated from culture filtrates of Pseudomonas fluorescens W51 and purified to apparent homogeneity. The enzyme catalyzed a random eliminative cleavage of pectin but not sodium polypectate, and it macerated plant tissue. The Mr of the PNL on sodium dodecyl sulfate-polyacrylamide gels was 32,000 +/- 1,000, and the isoelectric point was 9.4 as determined by isoelectric focusing. The enzyme was constitutively produced, since the highest yields were obtained when glycerol was used as a sole carbon source, and addition of pectin to the medium did not increase its production. Antibodies against purified PNL reacted in Western blots (immunoblots) with a pectate lyase (PLb) produced by Erwinia chrysanthemi EC16. The PNL appeared to be the only factor secreted into the culture medium by P. fluorescens W51 which macerated plant tissue and is probably involved in the soft rot disease caused by the bacterium.     

Litter decomposition of exotic and native plant species of agricultural importance in Amazonian streams

Limnology - The conversion of riparian vegetation into monocultures alters the input of allochthonous energy and the heterotrophy of streams. Here, we aimed to assess the implication of leaf litter...