Nucleus-Independent Chemical Shift (NICS) as a Criterion for the Design of New Antifungal Benzofuranones

The assertion made by Wu et al. that aromaticity may have considerable implications for molecular design motivated us to use nucleus-independent chemical shifts (NICS) as an aromaticity criterion to evaluate the antifungal activity of two series of indol-4-ones. A linear regression analysis of NICS and antifungal activity showed that both tested variables were significantly related (p < 0.05); when aromaticity increased, the antifungal activity decreased for series I and increased for series II. To verify the validity of the obtained equations, a new set of 44 benzofuran-4-ones was designed by replacing the nitrogen atom of the five-membered ring with oxygen in indol-4-ones. The NICS(0) and NICS(1) of benzofuran-4-ones were calculated and used to predict their biological activities using the previous equations. A set of 10 benzofuran-4-ones was synthesized and tested in eight human pathogenic fungi, showing the validity of the equations. The minimum inhibitory concentration (MIC) in yeasts was 31.25 µg·mL^–1 for Candida glabrata, Candida krusei and Candida guilliermondii with compounds 15-32, 15-15 and 15-1. The MIC for filamentous fungi was 1.95 µg·mL^–1 for Aspergillus niger for compounds 15-1, 15-33 and 15-34. The results obtained support the use of NICS in the molecular design of compounds with antifungal activity.

Study of Titanium-Silver Monolayer and Multilayer Films for Protective Applications in Biomedical Devices

The search for coatings that extend the useful life of biomedical devices has been of great interest, and titanium has been of great relevance due to its innocuousness and low reactivity. This study contributes to the investigation of Ti/Ag films in different configurations (monolayer and multilayer) deposited by magnetron sputtering. The sessile droplet technique was applied to study wettability; greater film penetrability was obtained when Ag is the external layer, conferring high efficiency in cell adhesion. The morphological properties were characterized by SEM, which showed porous nuclei on the surface in the Ag coating and crystals embedded in the Ti film. The structural properties were studied by XRD, revealing the presence of TiO2 in the anatase crystalline phase in a proportion of 49.9% and the formation of a silver cubic network centered on the faces. Tafel polarization curves demonstrated improvements in the corrosion current densities of Ag/Ti/Ag/Ti/Ag/Ti/Ag/Ti and Ti/Ag compared to the Ag coating, with values of 0.1749, 0.4802, and 2.044 nA.m-2, respectively. Antimicrobial activity was evaluated against the bacteria Pseudomonas aeruginosa and Bacillus subtilis and the yeasts Candida krusei and Candida albicans, revealing that the Ti/Ag and Ag/Ti/Ag/Ti/Ag/Ti/Ag/Ti coatings exhibit promise in biomedical material applications.

An Outbreak ofPichia anomalaFungemia in a Brazilian Pediatric Intensive Care Unit

Objective:

To report an outbreak ofPichia anomalafungemia that occurred in a Brazilian pediatric intensive care unit (ICU) from October 2002 to January 2004.

Design:

Unmatched case-control study.

Methods:

We randomly selected four control-patients for each case-patient from a list of all patients admitted to the ICU for at least 48 hours during the outbreak. A second control group was composed of all consecutive patients with nosocomial candidemia in the ICU during the outbreak. An environmental study was performed, and genetic relatedness among the clinical isolates was characterized by randomly amplified polymorphic DNA assay.

Results:

During the study period, 1,046 children were admitted to the pediatric ICU, 17 of whom developedP. anomalafungemia (attack rate, 1.6%). The median age was 1.1 years, and the main underlying conditions were congenital malformations (35.3%) and neoplastic diseases (11.8%). The overall mortality rate was 41.2%. Two patients received no antifungal treatment; all of the others were treated with amphotericin B. On multivariate analysis, only the presence of a central venous catheter was significantly associated withP. anomalafungemia. The yeast was not found on healthcare workers' hands or in the environment. Molecular studies showed that the outbreak was caused by a single strain. The distribution of risk factors was similar between patients withP. anomalafungemia and control-patients with candidemia.

Conclusions:

This study highlights the importance ofP. anomalaas an emerging nosocomial fungal pathogen. Patients withP. anomalafungemia seem to have risk factors in common with those who have candidemia.

A double WAP domain-containing protein from Chinese mitten crab Eriocheir sinensis with antimicrobial activities against Gram-negative bacteria and yeast

The whey acidic protein (WAP) domain is characterized by a 'four-disulfide-core' (4-DSC) motif comprising of approximately 50 amino acids with eight highly conserved cysteine residues. Previous research indicated that WAP domain-containing proteins played an important role in the innate immunity of crustaceans. In the present study, a novel double WAP domain (DWD)-containing protein gene was identified from Chinese mitten crab Eriocheir sinensis (designated EsDWD) by expressed sequence tag (EST) analysis and PCR techniques. The full-length cDNA of EsDWD was of 593 bp, consisting of a 5'-terminal untranslated region (UTR) of 71 bp, a 3' UTR of 120 bp with a polyadenylation signal sequence AATAAA and a polyA tail, and an open reading frame (ORF) of 402 bp. The ORF encoded a polypeptide of 133 amino acids with the predicted molecular weight of 14.4 kDa and the theoretical isoelectric point of 8.14, including a signal peptide of 22 amino acids and two WAP domains. The EsDWD mRNA transcripts were ubiquitously expressed in all the tested tissues, and its expression level in gill was significantly higher than that in other tissues. The mRNA expression of EsDWD in haemocytes was up-regulated after challenge of Vibrio anguillarum and Pichia pastoris GS115, as well as injury treatment. The cDNA encoding the mature EsDWD protein was cloned and expressed in Escherichia coli BL21 (DE3) pLysS, and the purified recombinant EsDWD (rEsDWD) protein exhibited antimicrobial activities against Gram-negative bacteria V. anguillarum, yeast P. pastoris GS115 and Candida parapsilosis. The results collectively suggested that EsDWD was a novel member of double WAP domain (DWD)-containing proteins, and involved in the immune defense against microorganism and wound healing in E. sinensis.

The second anti-lipopolysaccharide factor (EsALF-2) with antimicrobial activity from Eriocheir sinensis

The anti-lipopolysaccharide factor (ALF) is a small basic protein that can bind and neutralize lipopolysaccharide (LPS), mediating degranulation and activation of an intracellular coagulation cascade. In the present study, cDNA of the second Eriocheir sinensis ALF (designated as EsALF-2) was cloned and the full-length cDNA of EsALF-2 was of 724bp, consisting of an open reading frame (ORF) of 363bp encoding a polypeptide of 120 amino acids. The deduced amino acid of EsALF-2 shared 82% similarity with EsALF-1 from E. sinensis and about 53-65% similarity with ALFs from other crustaceans. The potential tertiary structures of EsALF-1 and EsALF-2 contained two highly conserved-cysteine residues to define the LPS binding site, but the N-terminal of EsALF-1 formed a single additional alpha-helix compared to EsALF-2, implying that EsALF-1 and EsALF-2 might represent different biological functions in E. sinensis. The mRNA transcript of EsALF-2 was detected in all examined tissues of healthy crabs, including haemocytes, hepatopancreas, gill, muscle, heart and gonad, which suggested that EsALF-2 could be a multifunctional molecule for the host immune defense responses and thereby provided systemic protection against pathogens. The mRNA expression of EsALF-2 was up-regulated after Listonella anguillarum and Pichia pastoris challenge and the recombinant protein of EsALF-2 showed antimicrobial activity against L. anguillarum and P. pastoris, indicating that EsALF-2 was involved in the immune defense responses in Chinese mitten crab against L. anguillarum and P. pastoris. These results together indicated that there were abundant and diverse ALFs in E. sinensis with various biological functions and these ALFs would provide candidate promising therapeutic or prophylactic agents in health management and diseases control of crab aquaculture.

AiC1qDC-1, a novel gC1q-domain-containing protein from bay scallop Argopecten irradians with fungi agglutinating activity

The globular C1q-domain-containing (C1qDC) proteins are a family of versatile pattern recognition receptors via their globular C1q (gC1q) domain to bind various ligands including several PAMPs on pathogens. In this study, a new gC1q-domain-containing protein (AiC1qDC-1) gene was cloned from Argopecten irradians by rapid amplification of cDNA ends (RACE) approaches and expressed sequence tag (EST) analysis. The full-length cDNA of AiC1qDC-1 was composed of 733bp, encoding a signal peptide of 19 residues and a typical gC1q domain of 137 residues containing all eight invariant amino acids in human C1qDC proteins and seven aromatic residues essential for effective packing of the hydrophobic core of AiC1qDC-1. The gC1q domain of AiC1qDC-1, which possessed the typical 10-stranded beta-sandwich fold with a jelly-roll topology common to all C1q family members, showed high homology not only to those of C1qDC proteins in mollusk but also to those of C1qDC proteins in human. The AiC1qDC-1 transcripts were mainly detected in the tissue of hepatopancreas and also marginally detectable in adductor, heart, mantle, gill and hemocytes by fluorescent quantitative real-time PCR. In the microbial challenge experiment, there was a significant up-regulation in the relative expression level of AiC1qDC-1 in hepatopancreas and hemocytes of the scallops challenged by fungi Pichia pastoris GS115, Gram-positive bacteria Micrococcus luteus and Gram-negative bacteria Listonella anguillarum. The recombinant AiC1qDC-1 (rAiC1qDC-1) protein displayed no obvious agglutination against M. luteus and L. anguillarum, but it aggregated P. pastoris remarkably. This agglutination could be inhibited by d-mannose and PGN but not by LPS, glucan or d-galactose. These results indicated that AiC1qDC-1 functioned as a pattern recognition receptor in the immune defense of scallops against pathogens and provided clues for illuminating the evolution of the complement classical pathway.

The strange case of a biofilm-forming strain ofPichia fermentans, which controlsMoniliniabrown rot on apple but is pathogenic on peach fruit

A biofilm-forming strain of Pichia fermentans proved to be most effective in controlling brown rot on apple fruit when coinoculated into artificial wounds with a phytopathogenic isolate of Monilinia fructicola. Culture filtrates and autoclaved cells had no significant influence on the disease. When sprayed onto the apple fruit surface, this yeast formed a thin biofilm but failed to colonize the underlying tissues. When inoculated into wounds artificially inflicted to peach fruit or when sprayed onto the surface of peach fruit, the same strain showed an unexpected pathogenic behaviour, causing rapid decay of fruit tissues even in the absence of M. fructicola. Both optical and scanning electron microscopy were used to evaluate the pattern of fruit tissue colonization by P. fermentans. While on apple surface and within the apple wound the antagonist retained its yeast-like shape, colonization of peach fruit tissue was always characterized by a transition from budding growth to pseudohyphal growth. These results suggest that pseudohyphal growth plays a major role in governing the potential pathogenicity of P. fermentans, further emphasizing the importance of a thorough risk assessment for the safe use of any novel biocontrol agent.

Structural and functional analysis of the killer element pPin1-3 from Pichia inositovora

Strains of the yeast Pichia inositovora that carry the linear plasmids pPin1-1 (18 kb) and pPin1-3 (10 kb) display a killer activity towards Saccharomyces cerevisiae. Cloning and sequencing of the smaller plasmid, pPin1-3, revealed that it is 9683 bp long and has 154-bp terminal inverted repeats. Comparison of pPin1-3 with the only other completely sequenced killer plasmid, pGKL1 of Kluyveromyces lactis, revealed differences in genome organization. The Pichia element has four ORFs that account for 95% of the sequence. ORF1 is homologous to the putative immunity gene of the K. lactis system. A viral B-type DNA polymerase is encoded by ORF2. The predicted product of ORF3 displays similarities to the alpha- and beta-subunits of the heterotrimeric K. lactis killer toxin, also known as zymocin. A cysteine-rich chitin-binding site and a chitinase signature, characteristic for the alpha-subunit of zymocin were identified in Orf3p. Chitin affinity chromatography and Western analysis confirmed the plasmid specific expression and secretion of a protein that cross-reacts with an antibody raised against the alpha-subunit of K. lactis zymocin. Disruption of the major chitin synthase-gene ( CHS3) renders S. cerevisiae resistant to the toxin, providing further evidence that chitin is the cellular receptor for the P. inositovora toxin. Orf4p of pPin1-3 displays only weak similarities to the gamma-subunit of zymocin, which causes a G1 cell-cycle arrest in S. cerevisiae. However, disruption of the S. cerevisiae gene ELP3/TOT3, which encodes a histone-acetyltransferase that is essential for zymocin action, resulted in reduced sensitivity to the P. inositovora toxin also. Thus, despite obvious differences in genome organization and protein architecture, both killer systems very probably have similar modes of action.

A tobacco S-like RNase inhibits hyphal elongation of plant pathogens

Ribonuclease (RNase) NE gene expression is induced in tobacco leaves in response to Phytophthora parasitica. Using antibodies directed against RNase NE, we demonstrate that RNase NE is extracellular at the early steps of the interaction, while the fungal tip growth is initiated in the apoplastic compartment. After production in Pichia pastoris and biochemical purification, we show that the S-like RNase NE inhibits hyphal growth from P. parasitica zoospores and from Fusarium oxysporum conidia in vitro. Conversion into an enzymatically inactive form after mutagenesis of the active site-histidine 97 residue to phenylalanine leads to the suppression of this activity, suggesting that RNase NE inhibits the elongation of germ tubes by degradation of microbial RNAs. Exogenous application of RNase NE in the extracellular space of leaves inhibits the development of P. parasitica. Based on its induction by inoculation, its localization, and its activity against two plant pathogens, we propose that RNase NE participates in tobacco defense mechanisms by a direct action on hyphal development in the extracellular space. The RNase activity-dependent antimicrobial activity of the S-like RNase NE shares similarities with the only other biological activity demonstrated for plant RNases, the inhibition of elongation of pollen tubes by the S-RNase in gametophytic self-incompatibility, suggesting a functional link between self and nonself interactions in plants.

Search for a novel killer toxin in yeast Pichia pastoris

Certain yeast strains secrete a protein toxin, which inhibits the growth of sensitive pathogens and yeasts. Studies have shown that production of the toxin is dependent on presence of linear, double-stranded DNA plasmids in the killer yeasts. In the yeast Pichia pastoris, two linear double-stranded DNA plasmids have been identified. In the present study, the search for toxin-producing capability in P. pastoris has been conducted. No killer activity could be detected when 14 different indicator strains were tested.

Pathogenicity of Hansenula anomala in model of immunocompromised mice

Systemic infections caused by opportunistic fungi have shown an increased frequency in the past 10 years, particularly in immunocompromised patients. Hansenula anomala is an ascosporogenous yeast of the Ascomycetes class found in the skin, throat, and digestive tract transient normal flora. This study was conducted to compare the pathogenicity of H. anomala and Candida albicans in a model of immunocompromised mice. Thirty-eight Swiss mice were divided into two groups as follows: 30 animals received an intraperitoneal (i.p.) injection of cyclophosphamide (200 mg/kg) four days before the induction of infection with H. anomala (1 x 10(6) yeasts/mL), and 8 animals received 100 mg/kg of cyclophosphamide at 3-day intervals during 3 weeks before inoculation of 1 x 10(7) yeasts/mL. All animals were treated with amoxicillin/clavulanic acid (40 mg/kg) four days before induction of infection. A group of mice inoculated with C. albicans (ATCC 64548) served as control. Tissue samples from the lung, spleen, liver, and kidney for histological and mycologic studies were obtained at necropsy. In each animal, the number of viable yeasts per gram of kidney was determined. The organs most frequently infected by H. anomala were the kidneys and the liver (20%), and the lung (10%). However, in conditions of sustained immunosuppression, H. anomala was found in 65.5% of the organs examined. It is concluded that in an experimental model of immunocompromised mice, the pathogenicity of H. anomala was low.

False-positive serologic test resulting from a probable yeast infection in a chimpanzee

Sera used to identify putative hepatitis E viral proteins expressed in Pischia pastoris produced a false-positive reaction because of antibodies to a yeast protein. This report illustrates a potential problem when serological reagents are used in combination with recombinant proteins expressed in yeast.

Killer factor interference in mixed opportunistic yeast cultures

The interaction of the killer yeast Pichia anomala UP 25F with the killer toxin-sensitive clinical isolate Candida albicans UCSC 10S and its natural toxin-resistant mutant derivative C. albicans UCSC 10R were studied under various conditions. A differential inhibition was shown to occur in vitro at pH and temperature values, which are not encountered in vivo, only by using preformed killer toxin, since antagonism due to yeast growth proved to be predominant on the killer effect. Under adverse growth conditions, the P. anomala killer yeast proved to be able to produce an anatoxin antigenically related to the active or heat inactivated killer toxin. These findings suggest that killer toxins may not function as potential virulence factors in the competition between the opportunistic killer yeast P. anomala and sensitive microorganisms for colonization in the course of natural human infections.

Hansenula anomala infection after bone marrow transplantation

Hansenula anomala is a yeast which has seldom been reported as a human pathogen. A case of fungaemia with this organism is described in a 22-year-old patient with chronic myeloid leukaemia undergoing a second HLA-matched sibling transplant. A Hickman catheter was in situ and hyperalimentation commenced on day -1. Fever developed on day +10 and H. anomala was isolated from blood cultures. The patient was receiving cyclosporin and methotrexate as prophylaxis against graft-versus-host disease and was severely neutropenic. Treatment with amphotericin B was commenced and the patient's Hickman catheter was removed. Fever resolved and subsequent blood cultures were negative. Amphotericin was continued to a cumulative dose of 680 mg and oral fluconazole 400 mg/day was given for a further week. H. anomala infection has been reported in premature babies and in immunosuppressed individuals but has not been previously observed in patients undergoing bone marrow transplantation. Clinical features of previously reported cases of infection with H. anomala are reviewed.

Fungemia caused by Hansenula anomala: successful treatment with fluconazole

Fungemia, due to Hansenula anomala, developed in an adult patient with small cell lung cancer who received anti-cancer chemotherapy and plasmapheresis for a sensori-motor neuropathy complication. Treatment with intravenous infusion of fluconazole in addition to the removal of the central venous catheter was successful in treating the fungemia. Pathogenic Hansenula anomala infections are rare, but reports of this infection have been increasing. The use of fluconazole treatment for this infection has not been reported in the literature, and this is the first case of an adult infection of Hansenula anomala in Japan.

[The effect of Pichia guilliermondii yeasts on the body of laboratory animals]

Conditionally pathogenic species Pichia guilliermondii which, being parenterally introduced to white mice, induced pathological changes in viscera and rarely death, has been revealed among species of genus Pichia previously considered as a nonpathogenic genus. The strains differ considerably between themselves in virulence. The latter does not depend on the yeast sex and the source of strain isolation.

Biotyping of micelial fungus cultures by the killer system

Based on the occurrence of the yeast killer phenomenon in hyphomycetes, the toxic effect of 37 selected killer yeasts was studied on eleven strains of Pseudallescheria boydii, six strains of Aspergillus niger, 18 strains of Penicillium camemberti and nine strains of Sporothrix schenckii. The demonstration of different biotypes within the species of P. boydii and P. camemberti proves that the killer system also is a practical and effective method for epidemiological studies among hyphomycetes. Based on the system used, it was not possible to observe markedly different biotypes among the A. niger and S. schenckii strains studied. The first evidence that an isolated, concentrated (50X) and partially purified yeast killer toxin may display a lethal activity against mycelial fungus cultures is also given in this paper.

In vitro phagocytosis of several Candida berkhout species by murine leukocytes

In vitro phagocytosis of thirteen Candida berkhout species by rat leukocytes was studied to assess a possible correlation between pathogenicity and phagocytosis Yeast-leukocyte suspensions were mixed up for 3 h and phagocytic index, germ-tube formation and leukocyte candidacidal activity were evaluated. Highest values for phagocytosis were reached in all cases at the end of the first hour. Leukocyte candidacidal activity was absent. Only C. albicans produced germ-tubes. The various phagocytosis indices were determined depending on the Candida species assayed. Under these conditions, the more pathogenic species presented the lower indices of phagocytosis. It is determined that the in vitro phagocytic index may bear a close relationship with the pathogenicity of the Candida berkhout.