Response of Caligus rogercresseyi (Boxshall & Bravo, 2000) to treatment with Hydrogen Peroxide: Recovery of parasites, fish infestation and egg viability under experimental conditions.

Hydrogen peroxide (HP) is used to remove C. rogercresseyi from fish but little is known about its effect on this species. This study determined EC50 and concentration immobilizing 100% of specimens, capacity of parasites exposed to HP to recover and infest fish, and effect on survival into the copepodid stage. EC50 and concentration immobilizing 100% of specimens were estimated by exposing parasites for 20 min to 11 concentrations and evaluating effect at 1 and 24 h post-exposure. Capacity to recover and infest fish, and survival into copepodid were evaluated by exposing parasites and eggs to HP for 20 min. Recovery and fish infestation were evaluated at 25 and 24 h post-exposure, respectively. Eggs were grown until control reached the copepodid stage and survival calculated. EC50 was 709.8 ppm.100% immobilization was obtained at 825 ppm. Male and female recover 0.5 and 1 h post-exposure, respectively. Percentage of parasites exposed and not exposed to HP that were recovered on fish was not significantly different. Survival to copepodid was lower in those exposed to HP. HP effect is greater on copepodids, but 100% of the mobile stages are immobilized under 825 ppm causing detachment from fish and potentially driven away, reducing infestation risk.

Ectoparasite Caligus rogercresseyi modifies the lactate response in Atlantic salmon (Salmo salar) and Coho salmon (Oncorhynchus kisutch).

Although Caligus rogercresseyi negatively impacts Chilean salmon farming, the metabolic effects of infection by this sea louse have never been completely characterized. Therefore, this study analyzed lactate responses in the plasma, as well as the liver/muscle lactate dehydrogenase (LDH) activity and gene expression, in Salmo salar and Oncorhynchus kisutch infested by C. rogercresseyi. The lactate responses of Atlantic and Coho salmon were modified by the ectoparasite. Both salmon species showed increasing in plasma levels, whereas enzymatic activity increased in the muscle but decreased in the liver. Gene expression was overexpressed in both Coho salmon tissues but only in the liver for Atlantic salmon. These results suggest that salmonids need more energy to adapt to infection, resulting in increased gene expression, plasma levels, and enzyme activity in the muscles. The responses differed between both salmon species and over the course of infection, suggesting potential species-specific responses to sea-lice infection.

Degradation of immobilized azo dyes by Klebsiella sp. UAP-b5 isolated from maize bioadsorbent.

The degradation of two immobilized dyes by Klebsiella sp. UAP-b5 was studied. In batch experiments, the azo dyestuffs Basic Blue 41 and Reactive Black 5 were immobilized onto corn cobs by adsorption, and the adsorption process was characterized by a pseudo-second-order kinetic equation. Klebsiella sp. UAP-b5 was previously isolated from the corn waste and shown to decolorize these dyes in liquid systems. Here, we demonstrate anaerobic decolorization and reductive biodegradation of these dyes by means of spectrophotometry, HPLC, and IR spectroscopy of the solid waste and desorption solutions. We also demonstrate adsorption of compounds that resemble known degradation products.

In situ and ex situ study of the enhanced modification with iron of clinoptilolite-rich zeolitic tuff for arsenic sorption from aqueous solutions.

Adsorption methods have been developed for the removal of arsenic from solution motivated by the adverse health effects of this naturally occurring element. Iron exchanged natural zeolites are promising materials for this application. In this study we introduced iron species into a clinoptilolite-rich zeolitic tuff by the liquid exchange method using different organic and inorganic iron salts after pretreatment with NaCl and quantified the iron content in all trials by XRF spectroscopy. The materials were characterized by XRD, FTIR, FTIR-DR, UV-vis, cyclic voltammetry, ESR and Mössbauer spectroscopies before and after adsorption of arsenite and arsenate. The reached iron load in the sample T+Fe was %Fe(2)O(3)-2.462, n(Fe)/n(Al)=0.19, n(Si)/n(Fe)=30.9 using FeCl(3), whereby the iron leachability was 0.1-0.2%. The introduced iron corresponded to four coordinated species with tetrahedral geometry, primarily low spin ferric iron adsorbing almost 12 mug g(-1) arsenite (99% removal) from a 360 mug(As(III)) L(-1) and 6 mug g(-1) arsenate from a 230 mug(As(V)) L(-1). Adsorption of arsenite and arsenate reached practically a plateau at n(Fe)/n(Si)=0.1 in the series of exchanged tuffs. The oxidation of arsenite to arsenate in the solution in contact with iron modified tuff during adsorption was observed by speciation. The reduction of ferric iron to ferrous iron could be detected in the electrochemical system comprising an iron-clinoptilolite impregnated electrode and was not observed in the dried tuff after adsorption.

Entamoeba histolytica: cyst-like structures in vitro induction.

The cyst of Entamoeba histolytica is responsible for amebiasis infection. However, no axenic in vitro system exists that promotes mass encystation for studying this process of this human-infecting parasite. Cyst-like structures of E. histolytica obtained in this work were induced using TYI-S-33 media in combination with enterobacterias Escherichia coli and Enterococcus faecalis conditioned media, high CO2 tension and histamine. Cyst-like structures showed the same characteristics of a typical E. histolytica cyst: aggregation, resistance to 0.15% sarcosyl for 10 min, high signal of fluorescence under UV light when stained with 10% calcofluor M2r and the surface topology showed a wrinkled wall. In addition these structures are multinucleated with condensed chromatin attached to nuclear membrane, contain big vacuoles and ribonucleoproteic helices in the cytoplasm and also present a thin cell wall. Last all characteristics are all the same as a typical of E. histolytica cyst.

Screening of commercial sorbents for removal of fluoride in synthetic and groundwater.

Numerous methods have been described employing various materials for fluoride removal due to the risk of high fluoride dosing for human health. There is a broad collection of commercial products for adsorption applications. The materials most recommended are activated alumina and bone char. Nineteen commercial sorbents were screened for fluoride removal in static experiments, with synthetic water and groundwater from the city of Aguascalientes (México), where some wells contain up to 15 mg l(-1) of fluoride. Removal efficiency of aluminas and activated carbons with a uniform particle diameter of 0.63 mm was compared. Four materials leading to a final concentration of 1 mg F- l(-1) were selected, pretreated, and characterized (X-ray diffractometry, infrared spectroscopy, titration, methylene blue and nitrogen adsorption) for further investigation. Adsorption rate constant was determined and obeyed a pseudo-first order equation. Fluoride removal was clearly improved after the conditioning procedure and was higher for aluminas than for bone carbons. The pretreated sample A5 adsorbed 5 mg g(-1) at 25 degrees C and pH 6 from a 20 mg F- l(-1) synthetic water solution after 7 hours by using a sorbent dose of 4 mg ml(-1). The specific saturation capacity with fluoride was aluminas - carbons for determined samples (10 mg g(-1), but the superficial capability was higher for the pretreated bone carbon sample CH5 (50 microg m(-2)) because of its higher acidity. At wells 4 and 5 (7.1 mg F- l(-1)) the reached efficiency was 91% for aluminas and 70% with bone carbon.

Interaction between organic vapors and clinoptilolite-mordenite rich tuffs in parent, decationized, and lead exchanged forms.

Scientific interest in adsorption phenomena of organic vapors has concentrated on synthetic zeolites. Solid-vapor systems containing natural zeolites deserve special attention due to their abundance and environmental applications. Adsorption thermodynamic characteristics for benzene, toluene, n-hexane, and CCl(4) were measured on clinoptilolite-rich zeolitic tuffs from Mexico (ZE) and Hungary (ZH) on parent, decationized, dealuminated, and lead-exchanged samples. The clinoptilolite structure released Na(+) and Ca(2+) by acid treatment and this was accompanied by dealumination to a greater extent on ZE than on ZH. The exchange isotherm of Pb(2+) on ZE exhibited a concave type "a" form and accomplished 95% exchange and the tuff was selective at X(i(s))<0.25. The pattern of adsorption isotherms was the same on all tuffs: benzene>toluene>n-hexane>carbon tetrachloride. The -DeltaH values were higher for toluene than for the other adsorbates. Curves of q(isost) vs coverage decreased with the increment of the adsorbed amount in practically all studied systems. The contributions to the solid-vapor interaction potential were examined using inverse gas chromatography. The specific interaction energy G(sp) was primarily due to adsorbate-framework and adsorbate-cation interactions at low adsorbate pressures producing low surface coverage.

Chromatographic and electrochemical determination of quercetin and kaempferol in phytopharmaceuticals.

An NP-HPLC method both with diode-array (DAD) and electrochemical detection (ED) was developed and validated for the determination of quercetin and kaempferol, the principal active constituents in phytopharmaceuticals of Ginkgo Biloba. Calculated retention of the two flavonoids was contrasted with experimental values in five different reversed phase columns for methanol-water, acetonitrile-water, THF-water and dioxane-hexane binary mixtures as mobile phases. The capacity factor k, selectivity alpha and asymmetry factor F were evaluated and compared in DAD-RP-HPLC, DAD-NP-HPLC, ED-RP-HPLC and ED-NP-HPLC. The methods were used for the quantitative analysis of acid hydrolyzed extracts of tablet phytopharmaceuticals. Calibration curves were linear within the range 10 and 40 microg ml(-1) for the DAD and 10-270 microg ml(-1) for the ED, whereby limits of detection ranged from 0.5 microg ml(-1) (quercetin) to 0.1 microg ml(-1) (kaempferol). The electrochemical method based on differential pulse voltammetry (DPV) with a C-PVC electrode resolved the quercetin and kaempferol peaks and exhibited a two orders higher sensitivity in comparison with a carbon fiber electrode. DPV calibration curves were linear within the range 96-300 microg ml(-1) for quercetin and 68-960 microg ml(-1) for kaempferol. The respective oxidation peaks appeared at 462 and 518+/-2 mV and were used in the direct determination of quercetin in extracts of commercial phytopharmaceuticals.

Entamoeba invadens: in vitro axenic encystation with a serum substitute.

The current media for axenic cultivation of Entamoeba histolytica and Entamoeba invadens are supplemented with bovine or equine serum, which provides several essential nutrients to amoebas. Serum has also been considered an essential component in encystation media for E. invadens. A substitute of serum, PACSR has been described as an alternative for growth of E. histolytica and also maintains growth of E. invadens. When PACSR was used instead of serum for encystation of E. invadens the efficiency was the same as for serum. Our present data show that PACSR can support the growth and induction of encystation of E. invadens strain IP-1.

Degradation of the textile dyes Basic yellow 28 and Reactive black 5 using diamond and metal alloys electrodes.

Basic yellow 28 (SLY) and Reactive black 5 (CBWB), which are respectively methine and sulfoazo textile dyes were individually exposed to electrochemical treatment using diamond-, aluminium-, copper- and iron-zinc alloy electrodes. The generated current was registered with time during electrolysis of the dye solutions and the color variation and the formation of degradation products were followed using HPLC with diode array detection. Four different electrodic materials were tested by applying different potentials in the range -1.0 to -2.5 V and presented 95% color removal and COD removal of up to 65-67% in the case of CBWB dye solution treated with the copper and iron electrodes. Efficiency was enhanced with stirring and flow in relation to the stationary regime. The kinetic parameter reaction rate was used to establish the effect of flow, potential, electrode nature and pH. The formation and characterization of the precipitate formed under certain conditions is reported and discussed.

Removal of metal ions from aqueous solution by adsorption on the natural adsorbent CACMM2.

The adsorption of Cd2+, Cr3+, Cu2+, Fe3+, Ni2+, Pb2+ and Zn2+ from aqueous solution was used to study the sorption properties of the adsorbent CACMM2 extracted from a cactus. Quantitation of the cation concentrations was performed by HPLC with diode array detection using on-column complex formation with 8-hydroxyquinoline. Removal degree from 100 mg M(n+) l(-1) solutions followed the series: Cu>Cd>Fe>Ni>Cr>Zn. Henry and Freundlich constants were determined since adsorption did not reach saturation plateaux in the studied concentration interval. Sorption of chromium by CACMM2 was stronger than the sorption onto lignin, calcium oxalate and cellulose up to 1,000 mg Cr3+ l(-1). Copper and iron were desorbed to a greater extent, while lead adsorption was practically irreversible. CACMM2 was able to remove more than 83% of chromate in a freshly prepared and exhausted chromate commercial solution.

Electrochemical treatment of textile dyes and their analysis by high-performance liquid chromatography with diode array detection.

Several textile dyes were individually exposed to electrochemical treatment. Chromaticity variation and the formation of degradation products were followed using a UV spectrophotometer and HPLC with diode array detection. Dyes studied belong to the azo (color index, C.I. 15,510), methine (C.I. 48,013), indigo (C.I. 73,040), natural (C.I. 75,760) and arylmethane (C.I. 42,000) classes. Aliquots of the solutions treated at constant potential were analyzed and compared with control dye solutions. The final electrolysis solutions obtained by using different electrode materials: Pt, Ti and diamond presented different chromatograms. It was found that the novel (in this application) diamond electrode is efficient in studying the degradation of various dyes. Possible fragmentation and molecule moiety rearrangement are proposed as a result of the electrochemical treatment.

Stability and determination of aflatoxins by high-performance liquid chromatography with amperometric detection.

A method based on reversed-phase high-performance liquid chromatography (RP-HPLC) with amperometric detection with a glassy carbon electrode at a constant potential of 1.4 V is reported for the separation and identification of aflatoxins B1, B2, G1 and G2 in a model mixture. The chromatography was performed on a PAH-Baker column with a ternary mobile phase containing methanol, acetonitrile and aqueous LiClO4 electrolyte. Aflatoxin G1 showed the highest electroactivity in the compound series studied. Calibration curves of aflatoxins G1 and B2 were linear up to 0.2 and 0.3 mmol/l, respectively. Sensitivity varied between 7 and 10 ng for the different aflatoxins. The combination of different HPLC detectors in the analysis of these compounds was applied to investigate the stability of aflatoxins G1 and B2.

Prevalencia del cáncer de vesícula biliar en colecistectomías / Biliary gallblader cancer prevalence in cholecystectomy

De 2.090 colecistectomías efectuadas en el Servicio de Cirugía del Hospital Valparaíso entre 1988 y 1990, el 2,9% presentó cáncer vesicular. El promedio de edad de los pacientes con cáncer fue de sólo 49 años, siendo la distribución por sexo similar. El cáncer estuvo asociado siempre a colecistitis crónica litiásica; se presentó avanzado (tipo III y IV de Nevin) y correspondió casi siempre a adenocarcinomas indiferenciados. La cirugía practicada fue la simple colecistectomía. La sobrevida de los 61 pacientes operados con cáncer de vesícula fue de 10,5% al año