Identification of distinct haemocyte populations from the freshwater bivalves swan mussel (Anodonta cygnea) and duck mussel (Anodonta anatina) using wheat-germ agglutinin

Haemocytes play a major role in molluscs immunity. Functional studies are, however, impaired by limited available experimental tools to identify and sort distinct haemocyte populations. Therefore, using nonlethal methods, we aimed at evaluating whether lectin staining combined with flow cytometry could be used to distinguish circulating haemocyte populations from two freshwater bivalves of the family Unionidae, the duck mussel (Anodonta anatina (L., 1758)) and the swan mussel (Anodonta cygnea (L., 1758)). Based on classical classification, haemocytes were distinguished as granulocytes and hyalinocytes and cytological features were visualized using transmission microscopy and staining techniques. Size, granularity, viability, and surface staining using lectins as specific probes were analysed by flow cytometry and fluorescence microscopy. The microscopic proportions of granulocytes and hyalinocytes significantly differed, being of 70% and 30% for A. cygnea and of 85% and 15% for A. anatina, respectively. Two haemocyte populations were sorted by flow cytometry based on size and granularity and confirmed as granulocytes and hyalinocytes. Interestingly, two different granulocyte populations could be further discriminated in A. cygnea according to their binding affinity to wheat-germ agglutinin (WGA), whereas granulocytes of A. anatina all stained similarly. Our results show that WGA labelling combined with flow cytometry can be used to better discriminate Anodonta haemocyte populations and obtain purified populations for functional studies.

Fibrous Histiocytoma-like Spindle-Cell Proliferation in the Nipple After Body-Piercing

We report the case of a 19-year-old pregnant woman who presented with a nipple tumor. The lesion consisted in a spindle-cell proliferation with histologic features similar to those of fibrous histiocytoma, with a highly vascularized stroma. Although it showed low mitotic activity, scattered marked atypical cells with prominent nucleoli were identified, thus raising concern about the benign nature of the tumor. Immunohistochemical evaluation revealed that the spindle cells were diffusely positive for vimentin, focally positive for CD68, and negative for all the other tested antibodies. The patient had a total excision of the lesion and she is free of disease after 30 months. To our knowledge this is the first reported case of a lesion of this type in the nipple after body-piercing.

Variability in chemical composition of Vitis vinifera cv Mencía from different geographic areas and vintages in Ribeira Sacra (NW Spain)

A chemical study was conducted from 2009 to 2012 to examine spatial and seasonal variability of red Vitis vinifera Mencía located in different geographic areas (Amandi, Chantada, Quiroga-Bibei, Ribeiras do Sil and Ribeiras do Miño) from NW Spain. Mencía samples were analysed for phenolic, (flavan-3-ols, flavonols, anthocyanins, acids and resveratrol), nitrogen (TAC, TAN, YAN and TAS) and volatiles compounds (alcohols, C6 compounds, ethyl esters, terpenes, aldehydes, acids, lactones, volatile phenols and carbonyl compounds) by GC-MS and HPLC. Results showed that the composition of Mencía cultivar was more affected by the vintage than the geographic area. The amino acid composition was less affected by both geographic origin and vintage, showing more varietal stability. Application of Principal Component Analysis (PCA) to experimental data showed a good separation of Mencía grape according to geographical origin and vintages. PCA also showed high correlations between the ripening ratio and C6 compounds, resveratrol and carbonyl compounds.

Mini-review: nucleus-targeted ribonucleases as antitumor drugs

Cancer is the leading cause of death in economically developed countries and the second leading cause of death in developing countries. This global burden of cancer continues to increase largely because of the aging and growth of the world population. Although very much progress has been attained in the development of new therapies, there is a clear need of more efficient and selective antitumor drugs for the effective treatment of many types of cancer. Among the different strategies developed to create new antitumor drugs, pleiotropic non-genotoxic effectors have gained interest since this approach is less susceptible to known resistance mechanisms. The cell nucleus is the subcellular compartment where the genetic information and the transcription machinery reside and accordingly where numerous therapeutic agents efficiently work. Hence, nuclear-targeted drugs are expected to kill cancer cells more directly and efficiently. In this review, we discuss the potential of nuclear-targeted drugs as antineoplastic therapeutics and reason the benefits of the strategy to endow ribonucleases with cytotoxic properties based on its targeting into the nucleus.

Volatile composition and sensory properties of Vitis vinifera red cultivars from north west Spain: correlation between sensory and instrumental analysis

The aroma and volatile composition of wines from five red cultivars from NW Spain (Brancellao, Mencía, Merenzao, Mouratón and Sousón) have been studied by gas chromatography-mass spectrometry (GC-MS) and sensory descriptive analysis (SDA) during three consecutive vintages (2007-2009) in order to characterize these wines. In addition, relationships between the instrumental (volatile) and sensory variables were analyzed through the application of partial least squares regression (PLSR). Results revealed that the effect of "cultivar" was very important as a third of compounds (16 in total) varied significantly (P≤0.05) among varieties. Mencía wines presented the highest concentrations of γ-nonalactone, whereas Sousón wines were the richest in monoterpene compounds. On the contrary, no significant difference was observed with respect to the esters content, probably as a consequence of using the same yeast for all vinifications. Twenty out of 51 quantified volatile compounds were present in some samples at concentrations higher than their corresponding odor thresholds (OAV>1), thus contributing to the final wine aroma. Partial least square (PLS) regression was applied to volatile compounds with OAV>0.2 and aroma descriptors with %GM>10. PLSR yielded a satisfactory model for the prediction of four important aroma descriptors in this set of wines--aroma quality, aroma intensity, herbaceous and red fruit--from instrumental analysis data. This work contributes to gaining knowledge about the sensory profiles and its relation to the volatile composition of minority Galician red grape cultivars.

[Iridoschisis associated to congenital syphilis: serological confirmation at the 80's]

CLINICAL CASE

Female in her eighties is admitted suffering from unilateral ocular pain. On examination we observed, as well as corneal abrasion, a bilateral iridoschisis with a frayed iris, unfolded between its stromal layers.

DISCUSSION

This rare case is related either to senile degenerative change or to angle-closure glaucoma. However, it is also associated with congenital syphilis with or without the presence of interstitial keratitis. Infant conjunctivitis and a "salt and pepper" appearance of the fundus oculi complete the diagnosis. It is confirmed that the patient had suffered from congenital late syphilis, cured by the age of 80: this confirmation is reached by treponemal (RPR-) and non-treponemal (TPHA+) serological tests.

The structural determinants that lead to the formation of particular oligomeric structures in the pancreatic-type ribonuclease family

Pancreatic-type ribonucleases are a family of RNA degrading enzymes that share different degrees of sequence identity but a very similar 3D-structure. The prototype of this family is bovine pancreatic ribonuclease or ribonuclease A. This enzyme has been the object of landmark work on the folding, stability, protein chemistry, catalysis, enzyme-substrate interaction and molecular evolution. In the recent years, the interest in the study of pancreatic-type ribonucleases has increased due to the involvement of some members of this family in special biological functions. In addition, dimeric and also higher oligomeric structures can be attained by the members of this family. The oligomers described structurally to date are mainly formed by 3D-domain swapping, a process which consists of the exchange of identical domains (i.e. identical structural elements, usually the N- and C-termini) between the subunits and is considered to be a mechanism for amyloid-type aggregate formation. This review compares the dimeric and oligomeric structures of different members of the pancreatic-type ribonuclease family which are able to acquire these structures, namely, bovine seminal ribonuclease, ribonuclease A and its human counterpart, human pancreatic ribonuclease. A specific focus is placed on what is known about the structural determinants that lead to the acquisition of a particular oligomeric structure and on the proposed mechanism of 3D-swapping.

Human pancreatic ribonuclease presents higher endonucleolytic activity than ribonuclease A

Analyzing the pattern of oligonucleotide formation induced by HP-RNase cleavage shows that the enzyme does not act randomly and follows a more endonucleolytic pattern when compared to RNase A. The enzyme prefers the binding and cleavage of longer substrate molecules, especially when the phosphodiester bond that is broken is 8-11 nucleotides away from at least one of the ends of the substrate molecule. This more endonucleolytic pattern is more appropriate for an enzyme with a regulatory role. Deleting two positive charges on the N-terminus (Arg4 and Lys6) modifies this pattern of external/internal phosphodiester bond cleavage preference, and produces a more exonucleolytic enzyme. These residues may reinforce the strength of a non-catalytic secondary phosphate binding (p2) or, alternatively, constitute a new non-catalytic phosphate binding subsite (p3).

Assimilable nitrogen utilisation and production of volatile and non-volatile compounds in chemically defined medium by Saccharomyces cerevisiae wine yeasts

Surveys conducted worldwide have shown that a significant proportion of grape musts are suboptimal for yeast nutrients, especially assimilable nitrogen. Nitrogen deficiencies are linked to slow and stuck fermentations and sulphidic off-flavour formation. Nitrogen supplementation of grape musts has become common practice; however, almost no information is available on the effects of nitrogen supplementation on wine flavour. In this study, the effect of ammonium supplementation of a synthetic medium over a wide range of nitrogen values on the production of volatile and non-volatile compounds by two high-nitrogen-demand wine fermentation strains of Saccharomyces cerevisiae was determined. To facilitate this investigation, a simplified chemically defined medium that resembles the nutrient composition of grape juice was used. Analysis of variance revealed that ammonium supplementation had significant effects on the concentration of residual sugar, L-malic acid, acetic acid and glycerol but not the ethanol concentration. While choice of yeast strain significantly affected half of the aroma compounds measured, nitrogen concentrations affected 23 compounds, including medium-chain alcohols and fatty acids and their esters. Principal component analysis showed that branched-chain fatty acids and their esters were associated with low nitrogen concentrations, whereas medium-chain fatty esters and acetic acid were associated with high nitrogen concentrations.

Varietal differences among the flavonoid profiles of white grape cultivars studied by high-performance liquid chromatography

In order to develop a method that allows to distinguish between white grape cultivars, the flavonoid profiles of 10 white accessions from the "Misión Biológica de Galicia" germplasm collection were studied during years 2003, 2004 and 2005 by high-performance liquid chromatography (HPLC). Twenty-four flavonoids (15 flavonols and 9 dihydroflavonols) were totally or partly identified, and significant differences between the studied flavonoid markers were found. With this method all the cultivars examined could be easily distinguished from each other, and we may conclude that this has been proved to be of great value for white grape cultivar recognition.

Analysis of the immune response to Neospora caninum in a model of intragastric infection in mice

To study experimental Neospora caninum infection initiated at the gastrointestinal tract, Toll-like Receptor 4- and functional IL-12Rbeta2 chain-deficient C57BL/10 ScCr mice were challenged intragastrically with 5 x 10(6) N. caninum tachyzoites. All parasite-inoculated mice eventually died with disseminated infection. In contrast, immunocompetent BALB/c mice challenged with 1 x 10(7) N. caninum tachyzoites by the intragastric (i.g.) or the intraperitoneal (i.p.) route remained alive for at least 6 months. Expansion of splenic B- and T-cells, the latter displaying both activated and regulatory phenotypes, and increased levels of IFN-gamma and IL-10 mRNA were detected in both groups of infected BALB/c mice compared with non-infected controls, whereas in the Peyer's patches only IFN-gamma mRNA levels were found to be increased. Parasite-specific IgG1, IgG2a and IgA antibody levels were elevated in the sera of all infected mice, whereas increased N. caninum-specific IgA levels were detected in intestinal lavage fluids of i.g. challenged mice only. These results show that N. caninum infection can be successfully established in mice by i.g. administration of tachyzoites. They also show that the immune response elicited in i.g. or i.p. infected BALB/c mice, although conferring some degree of protection, was not sufficient for complete parasite clearance.

Neospora caninum: high susceptibility to the parasite in C57BL/10ScCr mice

C57BL/10ScCr mice, lack Toll-like receptor 4 and a functional Interleukin-12 receptor. Taking this into account, susceptibility of these mice to Neospora caninum infection was assessed comparatively to that of immunocompetent C57BL/10ScSn mice. C57BL/10ScCr mice inoculated intraperitoneally with 5x10(5)N. caninum tachyzoites showed a high susceptibility to this parasite. All infected C57BL/10ScCr mice were dead by day 8 post-infection whereas all control C57BL/10ScSn mice survived this parasitic challenge. Immunohistochemical analysis of infected C57BL/10ScCr mice showed N. caninum tachyzoites spread in the pancreas, liver, lung, intestine, heart and brain whereas no parasites were detected in similarly infected C57BL/10ScSn controls. The higher susceptibility of C57BL/10ScCr mice to neosporosis correlates with reduced interferon-gamma mRNA expression and increased IL-4 mRNA expression, comparatively to C57BL/10ScSn controls, detected in the spleen after the parasitic challenge. C57BL/10ScCr mice could thus be used as a new experimental model where to study immunobiological mechanisms associated with host susceptibility to neosporosis.

A Cytotoxic Ribonuclease Variant with a Discontinuous Nuclear Localization Signal Constituted by Basic Residues Scattered Over Three Areas of the Molecule

Nuclear import of proteins is determined by specific signals that allow them to bind to receptors that mediate their energy-dependent transport through the nuclear pore. These signals are termed nuclear localization signals and do not constitute a specific consensus sequence. Among them, the most characterized correspond to monopartite and bipartite nuclear localization signals, which interact with the importin alpha/beta heterodimer. We previously described a cytotoxic variant of human pancreatic-ribonuclease that is actively transported into the nucleus. Here, we show that this protein interacts with importin alpha through different basic residues, including Lys1 and the arginine clusters 31-33 and 89-91. Although these residues are scattered along the sequence, they are close in the three-dimensional structure of the protein and their topological disposition strongly resembles that of a classical bipartite nuclear localization signal.

Pressure-jump-induced kinetics reveals a hydration dependent folding/unfolding mechanism of ribonuclease A

Pressure-jump (p-jump)-induced relaxation kinetics was used to explore the energy landscape of protein folding/unfolding of Y115W, a fluorescent variant of ribonuclease A. Pressure-jumps of 40 MPa amplitude (5 ms dead-time) were conducted both to higher (unfolding) and to lower (folding) pressure, in the range from 100 to 500 MPa, between 30 and 50 degrees C. Significant deviations from the expected symmetrical protein relaxation kinetics were observed. Whereas downward p-jumps resulted always in single exponential kinetics, the kinetics induced by upward p-jumps were biphasic in the low pressure range and monophasic at higher pressures. The relative amplitude of the slow phase decreased as a function of both pressure and temperature. At 50 degrees C, only the fast phase remained. These results can be interpreted within the framework of a two-dimensional energy surface containing a pressure- and temperature-dependent barrier between two unfolded states differing in the isomeric state of the Asn-113-Pro-114 bond. Analysis of the activation volume of the fast kinetic phase revealed a temperature-dependent shift of the unfolding transition state to a larger volume. The observed compensation of this effect by glycerol offers an explanation for its protein stabilizing effect.

Pressure as a tool to study protein-unfolding/refolding processes: The case of ribonuclease A

This paper gives an overview of the application of high-pressure to study the folding/unfolding processes of proteins using Ribonuclease A as a model protein. A particular focus is the study of pressure-equilibrium unfolding and folding kinetics using variants and the information obtained by comparing these with the wild-type enzyme.

Influence of batch or fed-batch growth on Staphylococcus epidermidis biofilm formation

AIMS

To make a quantitative evaluation of the differences in biofilm formation by Staphylococcus epidermidis using batch and fed-batch growth systems and to correlate this with production of the major biofilm polysaccharide, poly-N-acetyl glucosamine (PNAG).

METHODS AND RESULTS

Dry weight measurements of biofilms formed in batch and fed-batch conditions were compared with haemagglutination titres, which measure the amount of PNAG produced. Strains grown in batch systems developed less biofilm than when grown in fed-batch systems. A good correlation was found between the amount of biofilm formed in fed-batch systems and the haemagglutination titres.

CONCLUSIONS

Differences in biofilm formation and PNAG production by S. epidermidis are dependent on the availability of nutrients, with higher availability correlating with more biofilm and PNAG production. SIGNIFICANCE OF AND IMPACT OF THE STUDY: Comparisons of the formation of biofilms by S. epidermidis are dependent on choosing an appropriate biofilm growth system. Comparability or disparity of conclusions among different investigations will be strongly influenced by which mode S. epidermidis biofilms are formed.

Heterologous expression of the Saccharomyces cerevisiae PGU1 gene in Schizosaccharomyces pombe yields an enzyme with more desirable properties for the food industry

The Saccharomyces cerevisiae PGU1 gene was successfully expressed in Schizosaccharomyces pombe. The optimum pH and temperature for the recombinant enzyme were 5 and 40 degrees C, respectively, these being around 0.5 U higher and 5 degrees C lower than those shown by the native enzyme. The K(m) value was about fourfold higher than that of the S. cerevisiae enzyme. The recombinant endopolygalacturonase was more efficient in reducing the viscosity of polygalacturonic acid and was also more stable at different pHs and temperatures than the native enzyme.

Stabilization of human pancreatic ribonuclease through mutation at its N-terminal edge

Enzyme stability can be an important parameter in the design of recombinant toxins because unstable proteins are often degraded before they can reach their cellular target. There is great interest in the design of human pancreatic ribonuclease variants that could be cytotoxic against tumoral cells. To this end, some residues in the protein need to be substituted, but this may result in a loss of stability. Previous papers have reported the production of N- and C-terminal human pancreatic ribonuclease variants with increased thermal stability. Here, we investigated the contribution of the different amino acid changes at the N-terminus of the protein to its thermostability increase. We show that this increase correlates with the helical propensity of the first alpha-helix of the protein. On the other hand, deletion of the four last residues of the protein does not affect its thermal stability. These results set the basis for the design of a human pancreatic ribonuclease template on which amino acid substitutions can be made that could render the enzyme cytotoxic, without an important loss in its stability.

Cytometric, morphologic and enzymatic characterisation of haemocytes in Anodonta cygnea

The haemocytes in bivalve mussels are involved in many processes such as lesion repair, shell repair, elimination of small particles and toxic substances. In Anodonta cygnea there are two categories of haemolymph cells, the granulocytes and hyalinocytes. Two groups of cells were identified by flow cytometry and morphological studies: one with larger size and granularity representing 75%, and another group of cells (25%) which were approximately half the size. The cytochemical reactions showed peroxidase activity in the larger cells and a weak prophenoloxidase activity in the smaller cells. These characteristics suggest that the most common haemocytes are granulocytes and hyalinocytes are less common. Enzymatic studies showed clear activities of few enzymes in different compartments of the mantle. Both haemocytes presented significant variations for alpha-manosidase and beta-glucurosidase activities depending on the acid or alkaline pH. Almost all were sensitive to the pH changes, mainly the beta-galactosidase in the haemolymph plasma. On the contrary, the same enzymatic analysis in the extrapallial elements showed more stabilised activities. The simulation of acidic and alkaline condition with the observation of significant morphological and enzymatic activity changes, allow us to speculate some functional role, mainly in the haemolymph elements. The granulocytes may be speculated to have intense involvement in the digestion of small residues with the formation of calcareous stores while the hyalinocytes are more responsible for the elimination of soluble cytotoxic compounds.

Monitoring of the gasoline oxygenate MTBE and BTEX compounds in groundwater in Catalonia (northeast Spain)

Headspace (HS) gas chromatography with flame ionisation detection (HS-GC-FID) and purge and trap (P) gas chromatography-mass spectrometry (P) were used for the determination of methyl-tert-butyl ether (MTBE) and benzene, toluene, and xylenes (BTEX) in groundwater. In this work, we present the first data on the levels of MTBE and BTEX in different groundwater wells in the area of Catalonia (northeast Spain). This monitoring campaign corresponded to 28 groundwater wells that were located near petrol service stations, oil refinery storage tanks, and/or chemical industry at different locations of Catalonia during the period of 1998/1999. The levels of MTBE detected varied between 4-300 microg/l, but two sites had MTBE levels up to 3 and 13 mg/l. In many cases, the BTEX levels were below 1 microg/l, whereas 7 sites had levels varying from 19 microg/l up to 3 mg/l. Most of them were related to leakage from underground tanks in petrol service stations, while the remaining three corresponded respectively to chemical industrial pollution of undetermined origin and to a leak from high-ground petrol tanks in petrochemical refinery factories. The aquifers involved were constituted by detritus coarse materials, sands, and conglomerates. Piezometric levels were roughly comprised between 3 and 40 m, and permeability (K) and transmissivity (T) values were estimated from field measurements. The MTBE/BTEX ratio was also calculated and reached values up to 250. These values were expected, since if we consider that spilled oxygenated gasoline is the source of well contamination and based on solubility considerations alone, the MTBE source concentrations would be about 200 times higher than any BTEX compounds.

Fate of MTBE and DCPD compounds relative to BTEX in gasoline-contaminated aquifers

The aim of this communication is to provide preliminary results on MTBE monitoring, and at the same time to propose some new tracers of gasoline pollution in groundwater. An overview is presented on benzene-toluene-ethylbenzene-xylene (BTEX), methyl tertiary-butyl ether (MTBE), and dicyclopentadienes (DCPD) contents in gasoline formulations. Their specific fate in gasoline-contaminated aquifers are consistent with their physical-chemical properties.

Determination of drugs in surface water and wastewater samples by liquid chromatography-mass spectrometry: methods and preliminary results including toxicity studies with Vibrio fischeri

In the present work a combined analytical method involving toxicity and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) was developed for the determination of pharmaceutical compounds in water samples. The drugs investigated were the analgesics: ibuprofen, ketoprofen, naproxen, and diclofenac, the decomposition product of the acetyl salicylic acid: salicylic acid and one lipid lowering agent, gemfibrozil. The selected compounds are acidic substances, very polar and all of them are analgesic compounds that can be purchased without medical prescription. The developed protocol consisted, first of all, on the use Microtox and ToxAlert 100 toxicity tests with Vibriofischeri for the different pharmaceutical drugs. The 50% effective concentration (EC50) values and the toxicity units (TU) were determined for every compound using both systems. Sample enrichment of water samples was achieved by solid-phase extraction procedure (SPE), using the Merck LiChrolut EN cartridges followed by LC-ESI-MS. Average recoveries loading 11 of samples with pH=2 varied from 69 to 91% and the detection limits in the range of 15-56 ng/l. The developed method was applied to real samples from wastewater and surface-river waters of Catalonia (north-east of Spain). One batch of samples was analyzed in parallel also by High Resolution Gas Chromatography coupled with Mass Spectrometry (HRGC-MS) and the results have been compared with the LC-ESI-MS method developed in this work.

The structure of an engineered domain-swapped ribonuclease dimer and its implications for the evolution of proteins toward oligomerization

BACKGROUND

Domain swapping has been proposed as a mechanism that explains the evolution from monomeric to oligomeric proteins. Bovine and human pancreatic ribonucleases are monomers with no biological properties other than their RNA cleavage ability. In contrast, the closely related bovine seminal ribonuclease is a natural domain-swapped dimer that has special biological properties, such as cytotoxicity to tumour cells. Several recombinant ribonuclease variants are domain-swapped dimers, but a structure of this kind has not yet been reported for the human enzyme.

RESULTS

The crystal structure at 2 A resolution of an engineered ribonuclease variant called PM8 reveals a new kind of domain-swapped dimer, based on the change of N-terminal domains between the two subunits. The swapping is fastened at both hinge peptides by the newly introduced Gln101, involved in two intermolecular hydrogen bonds and in a stacking interaction between residues of different chains. Two antiparallel salt bridges and water-mediated hydrogen bonds complete a new interface between subunits, while the hinge loop becomes organized in a 3(10) helix structure.

CONCLUSIONS

Proteins capable of domain swapping may quickly evolve toward an oligomeric form. As shown in the present structure, a single residue substitution reinforces the quaternary structure by forming an open interface. An evolutionary advantage derived from the new oligomeric state will fix the mutation and favour others, leading to a more extended complementary dimerization surface, until domain swapping is no longer necessary for dimer formation. The newly engineered swapped dimer reported here follows this hypothetical pathway for the rapid evolution of proteins.

A randomised phase II study of oxaliplatin alone versus oxaliplatin combined with 5-fluorouracil and folinic acid (Mayo Clinic regimen) in previously untreated metastatic colorectal cancer patients

The aim of this study was to examine the efficacy and safety of both oxaliplatin as a single agent and oxaliplatin in combination with dailyx5 bolus 5-fluorouracil and folinic acid (5-FU/FA, Mayo clinic regimen) in the first-line treatment of metastatic colorectal cancer (CRC) patients. 73 advanced CRC patients were randomised to receive either oxaliplatin 85 mg/m(2) every 2 weeks (35 patients), or the same treatment combined with 5-FU 425 mg/m(2)/day and FA 20 mg/m(2)/dayx5 days every 4 weeks (38 patients). Treatment was continued until disease progression or unacceptable toxicity. All patients had documented inoperable disease and no previous chemotherapy for advanced disease. Based on the investigators' assessment of best response, objective response rate was 9% (95% confidence interval (CI) 2-24%) in the oxaliplatin arm, and 45% (95% CI 27-64%) in the oxaliplatin+5-FU/FA arm. Median progression-free survival (PFS) was 2 months (95% CI 1.7-2.4 months) in the oxaliplatin arm and 3.9 months (95% CI 2.9-5 months) in the oxaliplatin+5-FU/FA arm. Severe neutropenia was seen in 23% of patients in the oxaliplatin+5-FU/FA arm, and none in the oxaliplatin arm. There were two treatment-related deaths, both in the oxaliplatin+5-FU/FA arm. In the oxaliplatin+5-FU/FA arm, severe diarrhoea, vomiting and stomatitis were seen in 34, 14 and 14% of the patients, respectively. In conclusion, oxaliplatin at a dose of 85 mg/m(2) given every 2 weeks was well tolerated and has limited activity in metastatic CRC, while the combination of this treatment with the full-dose Mayo clinic regimen (5-FU bolus 425 mg/m(2)/day+FA 20 mg/m(2)/dayx5 days every 4 weeks), although active, was unfeasible due to a high level of myelosuppression and gastrointestinal toxicity. Alternative lower dosing or other regimens are to be explored to ascertain the value of bolus 5-FU/FA combined with oxaliplatin.

Pressure versus temperature unfolding of ribonuclease A: an FTIR spectroscopic characterization of 10 variants at the carboxy-terminal site

FTIR spectroscopy was used to characterize and compare the temperature- and pressure-induced unfolding of ribonuclease A and a set of its variants engineered in a hydrophobic region of the C-terminal part of the molecule postulated as a CFIS. The results show for all the ribonucleases investigated, a cooperative, two-state, reversible unfolding transition using both pressure and temperature. The relative stabilities, among the different sites and different variants at the same site, monitored either through the changes in the position of the maximum of the amide I' band and the tyrosine band, or the maximum of the band assigned to the beta-sheet structure, corroborate the results of a previous study using fourth-derivative UV absorbance spectroscopy. In addition, variants at position 108 are the most critical for ribonuclease structure and stability. The V108G variant seems to present a greater conformational flexibility than the other variants. The pressure- and temperature-denaturated states of all the ribonucleases characterized retained some secondary structure. However, their spectral maxima were centered at different wavenumbers, which suggests that pressure- and temperature-denaturated states do not have the same structural characteristics. Nevertheless, there was close correlation between the pressure and temperature midpoint transition values for the whole series of protein variants, which indicated a common tendency of stability toward pressure and heat.

Use of a PGU1 recombinant Saccharomyces cerevisiae strain in oenological fermentations

AIM

The aim of this work was the construction of an oenological Saccharomyces cerevisiae strain able to overexpress the PGU1 gene in order to be used in trial fermentations.

METHODS AND RESULTS

The recombinant strain is able to secrete an active endopolygalacturonase into the medium leaving its fermentation ability essentially unchanged. Wines obtained with the recombinant strain and the untransformed counterpart did not differ in their physicochemical parameters or major sensory characteristics. The time needed for wine filtration was dramatically reduced in wines elaborated with the PGU1 recombinant strain, and was comparable to the filtration time shown by wines elaborated from must supplemented with fungal pectolytic enzymes.

CONCLUSIONS

The oenological strain constructed in this work secretes an endopolygalacturonase into the wine in an efficient manner, resulting in an improvement in wine filtration but preserving wine typicality and keeping the methanol levels unchanged.

SIGNIFICANCE AND IMPACT OF THE STUDY

The PGU1 recombinant strains could be used in oenological fermentations as an alternative to commercial pectolytic enzymes of fungal origin.

Three-dimensional structure of a human pancreatic ribonuclease variant, a step forward in the design of cytotoxic ribonucleases

We have determined the crystal structure of a human pancreatic ribonuclease or RNase 1 variant at 1.65 A resolution. Five residues in the N-terminal region were substituted by the corresponding amino acids of the bovine seminal RNase. In addition, a Pro to Ser mutation was present at position 50. The substitution of part of the N terminus has been critical both in improving the expression of this enzyme as a recombinant protein and in achieving its crystallisation. The determination of the crystal structure revealed the characteristic RNase fold including a V-shaped beta-sheet and three alpha-helices. It differs from its bovine RNase orthologue mainly in the loop regions. The active-site cleft shows a similar architecture to that of its bovine counterpart, with the essential residues occupying equivalent positions. In the present structure, however, His119 is displaced as it is in the structure of RNase A at high pH. An interaction model of human ribonuclease with the ribonuclease inhibitor, together with inhibition assays, indicate that, in contrast to RNase A, the modification of the loop beta4beta5 is not enough to avoid inhibition. This study represents the first crystallographic approach to the human enzyme, and should constitute an invaluable tool for the design of ribonuclease variants with acquired cytotoxic properties.

Pressure versus heat-induced unfolding of ribonuclease A: the case of hydrophobic interactions within a chain-folding initiation site

To investigate the characteristics of the postulated carboxy terminal chain-folding initiation site in bovine pancreatic ribonuclease A (RNase A) (residues 106-118), important in the early stages of the folding pathway, we have engineered by site-directed mutagenesis a set of 14 predominantly conservative hydrophobic variants of the protein. The stability of each variant has been compared by pressure and temperature-induced unfolding, monitored by fourth derivative UV absorbance spectroscopy. Apparently simple two-state, reversible unfolding transitions are observed, suggesting that the disruption of tertiary structure of each protein at high pressure or temperature is strongly cooperative. Within the limits of the technique, we are unable to detect significant differences between the two processes of denaturation. Both steady-state kinetic parameters for the enzyme reaction and UV CD spectra of each RNase A variant indicate that truncation of hydrophobic side chains in this region has, in general, little or no effect on the native structure and function of the enzyme. Furthermore, the decreases in free energy of unfolding upon pressure and thermal denaturation of all the variants, particularly those modified at residues 106 and 108, suggest that the hydrophobic residues and side chain packing interactions of this region play an important role in maintaining the conformational stability of RNase A. We also demonstrate the potential of Tyr115 replacement by Trp as a non-destabilizing fluorescence probe of conformational changes local to the region.

Valine 108, a chain-folding initiation site-belonging residue, crucial for the ribonuclease A stability

Thermal denaturation of bovine pancreatic ribonuclease A and a set of its single variants, carrying replacements of hydrophobic residues in the postulated 106-118 chain folding initiation site, has been studied by differential scanning calorimetry. Ribonuclease A variants undergo a two-state thermal transition denaturation except for those with replacement of valine 108. Most mutations cause a significant destabilization of the protein compared to the wild-type, thus demonstrating the importance of hydrophobic residues at the 106-118 region in maintaining the stability of the molecule. Among them, those of valine 108 promote the greatest (14-27 degrees C) destabilization of the molecule. Therefore, valine 108 plays a crucial role for ribonuclease A stability.

Production of engineered human pancreatic ribonucleases, solving expression and purification problems, and enhancing thermostability

Human pancreatic ribonuclease, the homolog of bovine pancreatic ribonuclease, has a significant therapeutic potential. Its study has been hindered by the difficulty of obtaining the enzyme in a pure and homogeneous form, either from human source or using heterologous expression. Engineering of different variants of human pancreatic ribonuclease has allowed us to study and overcome some problems encountered during its heterologous production in an Escherichia coli system and its purification from inclusion bodies. The 5'-end region of the mRNA that encodes the enzyme is critical for obtaining high expression levels. The results also suggest the importance of the proline 50 residue in the recovery yields of human pancreatic ribonuclease. All the variants produced are pure and homogeneous. Their homogeneity has been demonstrated by cation-exchange and reversed-phase chromatography and by mass spectrometry analysis. Moreover, enhancement of human pancreatic ribonuclease thermal stability is observed when residues R4, K6, Q9, D16, and S17 are changed to the corresponding residues of bovine seminal ribonuclease.

The biological effects induced in mice by p36, a proteinaceous factor of virulence produced by African swine fever virus, are mediated by interleukin-4 and also to a lesser extent by interleukin-10

We have previously presented indirect evidence that both specific immunosuppression and lymphocyte mitogenicity induced in mice by p36, a proteinaceous factor of virulence produced by porcine monocytes infected by African swine fever virus, were consistent with a Th2-driven response. Here we show: (1) Interleukin-4 (IL-4) and interleukin-10 (IL-10) mRNA expression in the spleen and thymus of C57BL/6 mice were displayed early after p36 inoculation. The expression of thymic IL-10 mRNA occurred, however, later than that of IL-4 mRNA. (2) Increased serum levels of these two cytokines were also soon detected after the protein inoculation. (3) Both immunosuppressive and mitogenic effects of p36 were absent in IL-4 gene-targeted mice and partially abrogated in mice depleted of IL-4 by neutralizing monoclonal antibodies. (4) IL-10 depletion abrogated the immunosuppressive but not the p36 lymphocyte mitogenic biological effects. (5) The increase in the serum concentrations of both IL-4 and IL-10 were lower in thymectomized than in non-thymectomized mice. (6) The expression of interferon-gamma (IFN-gamma) mRNA was weakly or not at all induced in p36-treated mice. Taken together, these results are in agreement with the promotion of a Th2 immune response induced by p36.

The contribution of noncatalytic phosphate-binding subsites to the mechanism of bovine pancreatic ribonuclease A

The enzymatic catalysis of polymeric substrates such as proteins, polysaccharides or nucleic acids requires precise alignment between the enzyme and the substrate regions flanking the region occupying the active site. In the case of ribonucleases, enzyme-substrate binding may be directed by electrostatic interactions between the phosphate groups of the RNA molecule and basic amino acid residues on the enzyme. Specific interactions between the nitrogenated bases and particular amino acids in the active site or adjacent positions may also take place. The substrate-binding subsites of ribonuclease A have been characterized by structural and kinetic studies. In addition to the active site (p1), the role of other noncatalytic phosphate-binding subsites in the correct alignment of the polymeric substrate has been proposed. p2 and p0 have been described as phosphate-binding subsites that bind the phosphate group adjacent to the 3' side and 5' side, respectively, of the phosphate in the active site. In both cases, basic amino acids (Lys-7 and Arg-10 in p2, and Lys-66 in p0) are involved in binding. However, these binding sites play different roles in the catalytic process of ribonuclease A. The electrostatic interactions in p2 are important both in catalysis and in the endonuclease activity of the enzyme, whilst the p0 electrostatic interaction contributes only to binding of the RNA.

Purification, and biochemical and biological characterization of an immunosuppressive and lymphocyte mitogenic protein secreted by Streptococcus sobrinus

An immunosuppressive/mitogenic (ISM) protein was purified from the supernatants of cultures of Streptococcus sobrinus with an isoelectric point of 4.75 and a relative molecular mass of 38 kDa (p38). Treatment of C57BL/6 mice with p38 induced an increase in the numbers of non-specific splenic Ig-secreting plaque-forming cells (PFC) with peak responses on day 3 for IgM-secreting PFC and on day 5 for IgG-secreting PFC, with an isotype pattern consisting predominantly of IgG2a and IgG2b. This increase was accompanied by a lymphocyte blastogenic response of both T and B lymphocytes. The in vitro effects of p38 on pure B, T and total splenic lymphocytes indicated that this ISM protein was primarily a B cell mitogen, being T cells activated subsequently by the generation of B blasts. Suppression of the murine primary immune response against sheep red blood cells was observed in C57BL/6 mice treated 4 days before with p38. The amino acid sequence of the N-terminus of p38 has a significant similarity with several enolases, particularly with rabbit enolase. However, the biological effects ascribed to p38 have not been detected after in vivo treatment with that enolase. The immunosuppressive effect of p38 was abrogated by depletion of IL-10 but not of IL-4. In agreement with this observation IL-10 was the only cytokine detected in serum of C57BL/6 mice after p38 treatment and the peak of serum levels was observed as soon as 2 h after treatment.

Role of monocytes in the up-regulation of the early activation marker CD69 on B and T murine lymphocytes induced by microbial mitogens

CD69 is an early marker of lymphoid cell activation. The authors report on an up-regulation of CD69 in splenic B and T cells of C57Bl/6 mice after administration of lipopolysaccharide (LPS) or microbial immunosuppressive/mitogenic (ISM) proteins produced by C. albicans (p43) and African Swine Fever Virus (p36). This up-regulation of CD69 was observed 6 and 24 h after mitogenic treatments. The same pattern of increased CD69 expression was observed in the lymph nodes of mice treated with p43 or LPS, whereas p36 treatment failed to induce increased CD69 expression in this organ. Intracellular calcium mobilization was induced in splenic B and T lymphocytes after incubation of total spleen cells with LPS, p43 or p36. This increase was higher in B than in T cells. Increased calcium mobilization was also seen in lymph node B cells after incubation with p43 or p36 and in lymph node T cells after p43 stimulation. Up-regulation of CD69 expression on B and T cells was also observed after in vitro stimulation of spleen cells with the three mitogens used. Similar results were obtained with culture supernatants of macrophage/monocyte (M phi) cells activated with LPS (LPS/M phi CS). Stimulation of M phi cells with LPS or with the ISM proteins is demonstrated by the increased production of nitrites by these cells. The increased in vitro expression of CD69 was, however, not abolished by monoclonal antibodies to M phi cytokines such as IL-6, IL-10 or TNF alpha. No increased expression of CD69 was found in vitro on purified B or T cells, even when mixed upon stimulation with p43, p36, LPS or with LPS/M phi CS. However, an increase in the expression of CD69 was observed on B cells co-cultured with M phi cells after treatment with LPS or p36. All three mitogens failed to induce increased CD69 expression on cultured T cells mixed with M phi cells.

Flow Cytometric Analysis of Molt-Related Changes in Hemocyte Type in Male and Female Penaeus japonicus

Hemocyte cell suspensions obtained from male and female Penaeus japonicus were individually analyzed by flow cytometry through forward and side light-scatter parameters. The hemocyte cell suspensions were further characterized after cell sorting. This type of cell analysis has several advantages over microscopy techniques. After staining with phenoloxidase and peroxidase, the hemocytes were classified into the three classic categories of hyaline, semigranular, and granular cells. Significant cyclic differences were detected among the molting stages in both sexes. The hyaline cell population was predominant before and soon after the molt, decreasing over the intermolt. This decrease was, however, more prolonged in females. Thus, the hyaline cell population was dominant in stages B, D0, and D1 in males and only in stages B and D1 in females. Semigranular cells became predominant in females during the D0 stage.

Bovine pancreatic ribonuclease A as a model of an enzyme with multiple substrate binding sites

Bovine pancreatic ribonuclease A is an enzyme that catalyses the depolymerization of RNA. This process involves the interaction of the enzyme with the polymeric substrate in the active site and its correct alignment on the surface of the enzyme through multiple binding subsites that essentially recognize the negatively charged phosphate groups of the substrate. The enzyme shows a strong specificity for pyrimidine bases at the 3'-position of the phosphodiester bond that is cleaved and a preference for purine bases at the 5'-position and, probably, for guanine at the next position. On the other hand, the enzyme shows a clear preference for polynucleotide substrates over oligonucleotides. In this review the contributions to the catalytic mechanism of some amino-acid residues that are located at non catalytic binding subsites are analysed.

Immunoprotection against systemic candidiasis in mice

We have previously described an immunosuppressive B cell mitogenic (ISM) protein, p43, produced by Candida albicans, which plays an important role in the survival of the microorganism in the host. The N-terminal amino acid sequence of p43 was found to be different from all amino acid sequences registered in updated protein databanks. Immunization of BALB/c mice with p43 partially neutralized the biological effects of this protein, namely depletion of bone marrow pre-B and B cells, the increased numbers of total and large B and CD4+ lymphocytes, and the non-specific polyclonal response of splenic IgG2a-, IgG2b- and IgM-secreting plaque forming cells. Immunization of BALB/c mice with p43 fully protected the mice against the fungal infection. In contrast, immunization with C. albicans sonicates (Cs) was not protective. Our data indicated that specific antibodies against p43 protected, whereas those against Cs facilitated C. albicans infection. Thus, the ratio between anti-p43 and anti-Cs antibody titres was much lower in the non-protected mice (Cs-immunized and control non-immunized) than in p43-immunized mice. Moreover, passive administration of specific anti-p43 antibodies significantly protected against fungal infection, whereas passive administration of specific anti-Cs antibodies markedly increased the susceptibility to C. albicans infection. These observations are discussed on the basis of alternative approaches of immunointervention.

Immunostimulatory effect of thalidomide in normal C57BL/6 mice is compatible with stimulation of a highly connected central immune system

Although thalidomide has been used with success in the treatment of increasing numbers of autoimmune diseases, the therapeutic effects have not been satisfactorily explained so far. We describe here some findings that may contribute to a better understanding of the immunomodulatory effects of this drug. Several immunological changes were observed after treating C57BL/6 mice with 3 mg of thalidomide. The numbers of natural IgM PFC against sheep red blood cells were increased in the spleen, and occasionally a dramatic oscillatory increase in the numbers of non-specific splenic IgM and IgG PFC was observed in these mice. However, these oscillatory increases were progressively lower, after two and three treatments with thalidomide at 20-day intervals. Furthermore, the absolute numbers of splenic CD5+ B and CD5- B lymphocytes were increased whereas depletion of CD4+ CD8+ cells in the thymus and of lymphoid cells in the bone marrow was seen after a single treatment with 3 mg of thalidomide. Taken together, these results suggest that thalidomide stimulates both peripheral and central immune systems and consequently enhances the connectivity of the central immune system.