Differences in the In Vitro and In Vivo 5-Hydroxytryptamine Extraction Performance Among Three Common Microdialysis Membranes

The present study summarizes the results of an in vitro and in vivo comparison of the apparent 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid, and 3,4-dihydroxyphenylacetic acid dialysis performance of three types of membrane frequently used in intracerebral microdialysis experiments. The dialysis fiber types examined were a regenerated cellulose Cuprophan (GF), a proprietary polycarbonate ether (CMA), and a polyacrylonitrile/sodium methallylsulfonate copolymer (HOSPAL). The experiments unexpectedly revealed that the HOSPAL membrane-equipped probes displayed clearly aberrant 5-HT diffusion dynamics compared with GF and CMA probes, demonstrable not only in vitro, but also in in vivo experiments. In vitro, the GF and CMA membrane-equipped probes exhibited maximum relative recovery for 5-HT already in the first 20-min sample, whereas the 5-HT recovery of HOSPAL probes increased in a very slow and protracted manner over a period of a little less than 2 h. The GF and CMA probes further displayed an immediate washout of 5-HT when the probes were subsequently transferred to artificial CSF only-containing medium (no 5-HT), whereas approximately 2 h was required to yield near-total extinction of dialysate 5-HT with the standard HOSPAL probes. In vivo, the rat ventral hippocampal dialysate 5-HT output responses to K+ (100 mM) infusion, to Ca2+ omission, and to systemic 8-hydroxy-2-(di-n-propylamino)tetralin injection were all markedly retarded and blunted when HOSPAL instead of GF membrane-equipped probes were used. However, the 5-hydroxyindoleacetic acid and 3,4-dihydroxyphenylacetic acid extraction in vitro and in vivo were comparable using either of the membrane types.(ABSTRACT TRUNCATED AT 250 WORDS)     

Detection of a Cytosolic Glutamine Synthetase in Leaves of Nicotiana tabacum L. by Immunocytochemical Methods

Two glutamine synthetase (GS) polypeptides (44 and 39 kD) were immunodetected on western blots of leaf extracts from tobacco (Nicotiana tabacum L.), a plant that has been reported to contain only chloroplast GS in the leaves. By immunocytochemical methods, we confirmed the localization of GS in the cytosol of cells in the vascular tissue and in the chloroplasts of mesophyll cells.     

Immunocytolocalization of glutamine synthetase in mesophyll and phloem of leaves ofSolanum tuberosum L.

Summary Localization of glutamine synthetase inSolanum tuberosum leaves was investigated by techniques of Western tissue printing and immunogold electron microscopy. Anti-GS antibodies used in immunolocalization recognize two peptides (45 kDa and 42 kDa) on Western blots. Antibody stained tissue prints on nitrocellulose membranes allowed low resolution localization of GS. Immunostaining was most evident in the adaxial phloem of the leaf midribs and petiole veins. High-resolution localization of glutamine synthetase by immunogold electron microscopy revealed that this enzyme occurs in both the chloroplasts and the cytosol ofS. tuberosum leaf cells. However, GS was specifically associated with the chloroplasts of mesophyll cells and with the cytoplasm of phloem companion cells. The evidence for cell-specific localization of chloroplast and cytosolic GS presented here agrees with the recently reported cell-specific pattern of expression of GUS reporter gene, directed by promoters for chloroplast and cytosolic GS form in tobacco transgenic plants. These data provide additional clues to the interpretation of the functional role of these different isoenzymes and its relationship with their specific localization.Abbreviations BSA bovine serum albumin - EM electron microscope - GOGAT glutamate synthase - GS glutamine synthetase - GUS -glucuronidase - IgG immunoglobulin - PBS phosphate buffer saline - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis     

Hydrography and characteristics of the phytoplankton in shelf and oceanic waters off southeastern Brazil during winter (July/August 1982) and summer (February/March 1984)

The physical and chemical environment, and the phytoplankton primary production of southeastern Brazil were studied in relation to the general oceanographic structure during two research cruises (winter and summer). In each cruise, a total of 91 stations were occupied. Data were collected on the spatial distribution of nutrients, phytoplankton biomass and photosynthetic capacity over the coastal, shelf and oceanic areas off São Paulo, Paraná and Santa Catarina States.During wintertime, the mixing processes between tropical warm waters of the Brazil Current and subantarctic waters of the Malvinas Current formed strong environmental gradients. The drainings of Rio de La Plata and Lagoa dos Patos are transported northwards by coastal currents, enriching the shelf waters off Santa Catarina State with inorganic nutrients and consequently increasing the chlorophyll a to the highest concentrations (> 3.5 mg m ^–3) measured during the two cruises. In slope waters chlorophyll values were always low (0.05–0.45 mg m ^–3). The chlorophyll within the euphotic layer varied from 8.8–36.7 and 1.2–18.5 mg m^–2 during winter and summer, respectively.The surface photosynthetic rates during winter and summer cruises ranged respectively from 0.21–9.17 and 0.66–19.60 mgC/mgChl.a/h. The mean rates were higher in nearshore waters and decreased seaward.The thermal structure of the water column affected the vertical distribution of chlorophyll a and photosynthesis within the euphotic zone; During unstratified periods (winter) they were uniformly distributed but the occurrence of subsurface peaks of chlorophyll and strong photosynthetic inhibition of low light adapted cells in deeper layers are associated to the seasonal thermocline. Occasionally, upwelling of deep waters from shelf break enriched the deeper euphotic layers in offshore areas. Intensive upwelling was observed off Paranagua Bay (Parana State) and the mechanisms of its formation are discussed.     

Phosphorylation of the multicatalytic proteinase complex from bovine pituitaries by a copurifying cAMP-dependent protein kinase

The multicatalytic proteinase complex (MPC) constitutes a major nonlysosomal proteolytic system that may play an important role in the processing of biologically active peptides and enzymes, as well as in intracellular metabolism. We report that at least two of its subunits of MW 28,800 (S2) and 27,000 (S3) are phosphorylated by a cAMP-dependent protein kinase (PK-A) that copurifies with the complex isolated from bovine pituitaries. The cAMP-induced phosphorylation was time dependent and inhibited by a PK-A inhibitor. Although not an integral part of the complex, PK-A activity was still present even in 1700-fold-purified and apparently homogeneous preparations by criteria of nondissociating polyacrylamide gel electrophoresis. Furthermore, we present evidence that the copurification of the two enzymes is not species or tissue specific, or dependent on a single method of purification. The copurifying kinase was stimulated 10-fold by cAMP (10 microM) and 2- to 3-fold by a peptide substrate of the MPC, but was unaffected by protein kinase C activators (calcium and a phospholipid mixture). These findings suggest that protein phosphorylation may represent a mechanism for regulating the activity of the multicatalytic proteinase complex.     

Lack of relationship between activity of intestinal alkaline phosphatase and calcium or phosphate absorption

The effects of vitamin D3 and the aqueous extract of Solanum malacoxylon on intestinal alkaline phosphatase and tissue phosphate content were studied on rachitic chicks treated with large doses of ethane-1-hydroxy-1,1 diphosphonate (EHDP). The EHDP treatment blocks the increase of intestinal calcium or phosphate absorption induced by the vitamin D3, while it has no effects on the rise of intestinal alkaline phosphatase activity or the increment in tissue phosphate content. The lack of correlation between the increment of alkaline phosphatase and that of Ca or phosphate absorption in vitamin D3 plus EHDP treated chicks excludes a participation of the alkaline phosphatase in the mechanism of Ca or P intestinal absorption. The Ca or phosphorus absorption are elicited specifically by 1,25-(OH)2-D3, while alkaline phosphatase activity and phosphate tissue concentration respond to a broader spectrum of stimuli.     

A brief comparative study of four disposable bubble oxygenators

Four widely used bubble oxygenators-the Optiflo I, the Bentley Q 200 A, the Harvey 200, and the Shiley 100 A-were tested and compared in 182 patients undergoing cardiac valve surgery. Fifty-six cases were performed with normothermia and 126 cases incorporated mild hypothermia (28-30 degrees C). There was no significant difference in the average age of the patients (51 yrs) or the perfusion time (60 min). All components of the extracorporeal circuit were identical, and anesthetic regimens and surgical techniques were also similar. In this study, the Shiley 100 A oxygenator was found to be the most suitable for cases requiring mild hypothermia and was generally considered to be the oxygenator of choice.     

Inhibition of peroxidase by algal humic and fulvic acids

In contrast to their soil counterparts, algal fulvic acids were more inhibitory than the corresponding humic acids. Fulvic and humic acids fromFucus vesiculosus were more efficient than the correspondingLaminaria digitata acids in inactivating the enzyme.Laminaria humic acids, which have no phenolic hydroxyls, showed a concentration dependent inhibition hardly in accordance with the presumed role played by these groups in the activity of oxidases.     

Genetic variants of serum alpha1-antitrypsin (Pi types) in Portuguese.

The results of Pi typing on 330 Portuguese from the area of Lisbon are reported. We found six phenotypes and four alleles out of the 24 described in the literature. The allele PiM is the most frequent as in other populations, PiS shows a high frequency (0.1152), and PiF is absent, which agrees satisfactorily with former studies carried out in Spain. These results are compared with others and the entity of the Iberian population is evoked.     

Using Species Distribution Models to Predict Potential Landscape Restoration Effects on Puma Conservation

A mosaic of intact native and human-modified vegetation use can provide important habitat for top predators such as the puma (Puma concolor), avoiding negative effects on other species and ecological processes due to cascade trophic interactions. This study investigates the effects of restoration scenarios on the puma’s habitat suitability in the most developed Brazilian region (São Paulo State). Species Distribution Models incorporating restoration scenarios were developed using the species’ occurrence information to (1) map habitat suitability of pumas in São Paulo State, Southeast, Brazil; (2) test the relative contribution of environmental variables ecologically relevant to the species habitat suitability and (3) project the predicted habitat suitability to future native vegetation restoration scenarios. The Maximum Entropy algorithm was used (Test AUC of 0.84 ± 0.0228) based on seven environmental non-correlated variables and non-autocorrelated presence-only records (n = 342). The percentage of native vegetation (positive influence), elevation (positive influence) and density of roads (negative influence) were considered the most important environmental variables to the model. Model projections to restoration scenarios reflected the high positive relationship between pumas and native vegetation. These projections identified new high suitability areas for pumas (probability of presence >0.5) in highly deforested regions. High suitability areas were increased from 5.3% to 8.5% of the total State extension when the landscapes were restored for ≥ the minimum native vegetation cover rule (20%) established by the Brazilian Forest Code in private lands. This study highlights the importance of a landscape planning approach to improve the conservation outlook for pumas and other species, including not only the establishment and management of protected areas, but also the habitat restoration on private lands. Importantly, the results may inform environmental policies and land use planning in São Paulo State, Brazil.