Use of Generic Antiretroviral Drugs and Single-Tablet Regimen De-Simplification for the Treatment of HIV Infection in Spain

The present study sought to describe the use of generic drugs and single-tablet regimen (STR) de-simplification for the treatment of human immunodeficiency virus (HIV) infection among 41 hospitals from the cohort of the Spanish HIV/AIDS Research Network (CoRIS). In June 2018, we collected information on when generic antiretroviral drugs (ARVs) were introduced in the different hospitals, how the decisions to use them were made, and how the information was provided to the patients. Most of the nine available generic ARVs in Spain by June 2018 had been introduced in at least 85% of the participating hospitals, except for zidovudine (AZT)/lamivudine (3TC) and AZT. The time difference between the effective marketing date of each generic ARV and its first dispensing date in the hospitals was much shorter for the more recently approved generic ARV since the year 2017. However, only up to 20% of the hospitals de-simplified efavirenz (EFV)/tenofovir disoproxil (TDF)/emtricitabine (FTC), dolutegravir (DTG)/abacavir (ABC)/3TC, and rilpivirine (RPV)/TDF/FTC (to generic EFV+TDF/FTC, DTG+generic ABC/3TC, and RPV+generic TDF/FTC, respectively), whereas the generic STR EFV/TDF/FTC was introduced in 87.8% of the centers. The median times between the date of effective marketing of generic TDF/FTC and the date of de-simplification of EFV/TDF/FTC and RPV/TDF/FTC were 723 [interquartile range (IQR): 369-1,119] and 234 (IQR: 142-264) days, respectively; this time was 155 (IQR: 28-287) days for de-simplification of DTG/ABC/3TC. In conclusion, despite the widespread use of generic ARVs, STRs de-simplification was only undertaken in <20% of the hospitals. There was wide variability in the timing of the introduction of each generic ARV after they were available in the market.

The anti-CD6 antibody itolizumab provides clinical benefit without lymphopenia in rheumatoid arthritis patients: results from a 6-month, open-label Phase I clinical trial

Itolizumab is a humanized anti-CD6 monoclonal antibody (mAb) that has previously shown encouraging results, in terms of safety and positive clinical effects, in a 6-week monotherapy clinical trial conducted in rheumatoid arthritis (RA) patients. The current Phase I study evaluated the safety and clinical response for a longer treatment of 12 itolizumab intravenous doses in subjects with active RA despite previous disease-modifying anti-rheumatic drug (DMARD) therapy. Twenty-one subjects were enrolled into four dosage groups (0·1, 0·2, 0·4 and 0·8 mg/kg). Efficacy end-points including American College of Rheumatology (ACR)20, ACR50 and ACR70 response rates and disease activity score in 28 joints (DAS28) were monitored at baseline and at specific time-points during a 10-week follow-up period. Itolizumab was well tolerated up to the highest tested dose. No related serious adverse events were reported and most adverse events were mild. Remarkably, itolizumab treatment did not produce lymphopenia and, therefore, was not associated with infections. All patients achieved a clinical response (ACR20) at least once during the study. Eleven subjects (55%) achieved at least a 20% improvement in ACR just 1 week after the first itolizumab administration. The clinical response was observed from the beginning of the treatment and was sustained during 24 weeks. The efficacy profile of this 12-week treatment was similar to that of the previous study (6-week treatment). These results reinforce the safety profile of itolizumab and provide further evidence on the clinical benefit from the use of this anti-CD6 mAb in RA patients.

Evaluation of respiratory- and postural-induced changes on the ballistocardiogram signal by time warping averaging

OBJECTIVE

The aim of this work was to evaluate the potential changes in the ballistocardiogram (BCG) signal induced by different respiratory patterns and posture, by using the dynamic time warping (DTW) technique.

APPROACH

BCG signals were recorded in a group of 20 healthy volunteers, simultaneously with an electrocardiogram (ECG). Two recordings, one in a supine (SUP) and one in a standing (ST) position, including spontaneous breathing, two 1 min apneas (at full and empty-lungs, respectively) and 30 s of Valsalva, were analyzed. A warped averaged waveform was computed for each phase, from which amplitude and temporal parameters were extracted to characterize each condition.

MAIN RESULTS

Variations were found in both amplitude and duration of BCG-derived parameters among manoeuvres, especially when compared to spontaneous breathing, suggesting a complex interaction between intra-thoracic pressure changes acting on venous return, together with the autonomic nervous system modulation on heart rate. The effect of a hydrostatic pressure gradient elicited by postural conditions was also evident.

SIGNIFICANCE

Posture and respiratory manoeuvres affect the BCG signal in different ways, probably as a result of changes induced in preload and afterload. This supports the need to define separate normality ranges for each posture and/or breathing conditions, as well as the importance of applying specific manoeuvres to highlight any pathological response in the computed BCG parameters.

Voriconazole inhibits biofilm formation in different species of the genus Candida

OBJECTIVES

To determine the ability of voriconazole to inhibit the formation of biofilms.

METHODS

A total of 38 blood isolates of Candida spp. (8 Candida albicans, 10 Candida tropicalis, 10 Candida glabrata, 7 Candida parapsilosis sensu stricto and 3 Candida orthopsilosis) and C. albicans ATCC 90028 and ATCC 64548 were assessed. Biofilm formation was quantified using XTT reduction assays. The inhibition of biofilm formation was determined (i) in the presence of 0.06 and 0.25 mg/L voriconazole, and (ii) on surfaces previously coated with 0.06, 0.25, 1, 4 and 16 mg/L voriconazole.

RESULTS

Voriconazole reduced biofilm formation under both conditions, the extent depending on the species, isolate and drug concentration. In the presence of 0.25 mg/L, the highest reduction was found for C. parapsilosis (79% ± 8.6%), followed by C. albicans (64.5% ± 6.3%), C. tropicalis (53.3% ± 13.1%) and C. glabrata (23.8% ± 11.2%). This reduction was significant (P < 0.05) for all isolates tested. After coating the wells with voriconazole, biofilm formation was reduced in all Candida spp. examined, C. albicans being the species with the highest reduction (68.8% with 16 mg/L) and C. parapsilosis complex and C. glabrata the lowest.

CONCLUSIONS

As voriconazole reduces biofilm formation it may be a good candidate for the prevention of Candida biofilm-related infections although further studies using voriconazole-impregnated catheter tubing or prostheses are required to confirm these results.

Class 1 integrons in environmental and clinical isolates of Pseudomonas aeruginosa

The aims of this study were to ascertain the presence and spread of class 1 integrons amongst environmental and clinical isolates of Pseudomonas aeruginosa and to characterise their variable regions. A total of 76 isolates (56 clinical and 20 environmental) were studied. The presence of plasmids was explored, and polymerase chain reaction (PCR) was used for integron detection. All amplicons were sequenced. PCR detected class 1 integrons in 26 of the 56 clinical isolates; environmental isolates were integron-free. No plasmids were found, thus all the integrons found are possibly on the chromosome. Most isolates presented one amplicon, except PA110514 and PA116136, which showed two PCR products each. Variable regions revealed that 18 strains carried only one gene involved in aminoglycoside resistance, whereas in 3 strains gene cassettes were not found. The most prevalent cassettes amongst isolates were those encoding aminoglycoside adenyltransferase B (aadB). Several of the strains had acquired the same or a highly similar cassette array as those detected in geographically distant P. aeruginosa. This finding suggests that contact with bacterial reservoirs contributes to the evolution of this pathogen towards multiresistance. Empty structures found may represent a reservoir increasing the capacity to adapt to the environment. However, these integrons are not retained when the selective pressure disappears. It is hypothesised that integrons containing gene cassettes are crucial vehicles for the rapid horizontal transfer of resistance. If this is so, reduced use of antibiotics may lead to a significant decrease in the carriage of integrons amongst P. aeruginosa strains.

Detection of equine herpesvirus 1 genome 1B in Argentina

To determine the genomic variation of equine herpesviruses (EHVs) isolated in Argentina between 1979 and the first half of 2004, DNA sequences from all 69 strains isolated were analysed. Sixty strains were recovered from aborted fetuses, one from leucocyte-rich plasma from a horse with respiratory signs and eight from cases of neonatal disease. The DNA was extracted from rabbit kidney epithelial (RK13) cells infected with each strain and digested with three restriction endonucleases (BamHI, Bg/II and KpnI). Two strains could be differentiated using BamHI restriction and were assigned to the EHV-1 1B prototype group. Only one of these two strains was typed EHV-1 1B with Bg/II. DNA digestion with KpnI was ineffective. The results obtained in this study demonstrate that the EHV-1 1B genome has been present in Argentina since at least 1996. The finding of two strains with this electropherotype suggests that there is genomic heterogeneity among Argentinian isolates.

[Secondary osteoporosis]

Secondary osteoporosis is caused by pathologies or medications, differing from the bone loss explainable by the post-menopausal stage or by ageing. The possible pathologies that can condition the loss of bone mass are very varied: endocrinological, digestive, genetic, haematological, rheumatic, post-transplant, pharmacological and a wide miscellaneous group. This article essentially reviews the endocrinological causes, with special emphasis on the more controversial aspects, followed by a clinical approach for the systematic diagnosis of these pathologies, which are frequent in cases initially labelled as primary osteoporosis

Molecular cloning and characterization of the Candida albicans UBI3 gene coding for a ubiquitin-hybrid protein

Using a polyubiquitin cDNA as a probe, we have isolated a clone (pPR3, a pEMBLYe23 derivative plasmid) containing the Candida albicans UBI3 gene coding for a fusion protein. This protein is formed by one ubiquitin subunit fused, at its C-terminus, to an unrelated peptide which is similar to the ribosomal protein encoded by the 3' tail of the Saccharomyces cerevisiae UBI3 gene. Southern blot analysis of chromosomal DNA probed with the 3' non-ubiquitin tail of UBI3 indicated that only one homologous gene is present in the C. albicans genome. Heterelogous expression of pPR3 in a S. cerevisiae ubi3 mutant strain complements the mutant phenotype (slow growth) conferred by the ubi3 defect; this provides direct evidence indicating that the clone contains the C. albicans UBI3 gene Northern blot analysis showed that UBI3 gene is expressed in yeast and germ-tube cells of C. albicans, although the UBI3 mRNA levels in starved yeast cells are below the detection limit; UBI3 mRNA drops to undetectable levels on shifting the temperature of growing yeast cells from 28 degrees C to 42 degrees C. When Northern blot analysis was performed using a specific probe for the polyubiquitin (UBI4) gene, no drop in the mRNA levels was detected following thermal upshift or in starved cells. These results indicate that stress conditions (starvation or thermal upshift) negatively regulate UBI3 expression (transcriptional arrest and/or enhanced mRNA decay), and suggest that UBI4 gene provides ubiquitin during the stress response. In addition, we failed to obtain C. albicans UBI3 null mutant cells by sequential disruption of both alleles using the hisG::URA3::hisG ('ura-blaster') cassette, suggesting that null mutants cells may be unable to grow on selective media after transformation.

Löffler's syndrome: pulmonary vein and transmitral doppler flow analysis by transesophageal echocardiography-report of a case

Löffler's syndrome is defined by prolonged and profound eosinophilia and restrictive cardiomyopathy. Doppler echocardiography is useful in both the diagnosis and management of this entity. On the other hand, diastolic dysfunction is assessed better by transesophageal echocardiography than by transthoracic echocardiography, mainly in the analysis of pulmonary vein Doppler flow. We describe a patient with Löffler's syndrome, whose pulmonary vein flow, obtained by transesophageal echocardiography, was helpful for better management of the disease.

Identification of Candida albicans clinical isolates by PCR amplification of an EFB1 gene fragment containing an intron-interrupted open reading frame

The use of a single pair of primers, deduced from the intron and exon nucleotide sequences of the Candida albicans EFB1 gene, in polymerase chain reaction (PCR) assays performed with whole cells of both laboratory strains and clinical isolates of Candida species, resulted in the species-specific amplification of a 785 bp DNA fragment in C. albicans strains. Clinical C. albicans isolates were tested, and 85 out of 86 generated the expected PCR-amplified product; other Candida species, both laboratory strains and clinical isolates, as well as laboratory strains belonging to other fungal genera, including medically relevant taxa, failed to amplify any DNA fragment. In addition, unusual C. albicans isolates (glucosamine- and N-acetylglucosamine-negative) from Africa also yielded the expected PCR-generated DNA fragment. These results indicate that genes containing intron sequences may be useful to design species-specific primers for the identification of fungal strains by PCR.

Purification of a biologically active recombinant glyceraldehyde 3-phosphate dehydrogenase from Candida albicans

We report here the purification of a functionally active recombinant glyceraldehyde 3-phosphate dehydrogenase (GAPDH) from Candida albicans. The GAPDH protein encoded by the TDH1 gene was obtained as a glutathione S-transferase fusion protein by expression in the vector pGEX-4T-3, and purified by affinity chromatography and thrombin digestion. The purified protein displays GAPDH enzymatic activity (42 micromol NADH min(-1) mg(-1)) as well as the laminin and fibronectin binding activities previously described. In addition, the recombinant GAPDH is covalently modified by NAD linkage; this modification is stimulated by nitric oxide and probably involves a sulfhydryl group (cysteine) residue since it is inhibited by Hg(2+) and cysteine.

Mechanisms of action of quinolones against staphylococci and relationship with their in vitro bactericidal activity

Ciprofloxacin and norfloxacin exhibited mechanism A (requires cell division as well as bacterial protein and RNA synthesis to kill bacteria) and C (active against nondividing bacteria but requires protein and RNA synthesis) against the reference strain Staphylococcus aureus ATCC 25923, yet only mechanism A was exhibited by these fluoroquinolones when tested against three clinical isolates: S. aureus Sa-215, Staphylococcus epidermidis Se-81 and Staphylococcus haemolyticus Sx-1. On the contrary, fleroxacin exerted mechanism A and C against the three clinical isolates but only mechanism A against the reference strain. Ofloxacin displayed mechanism A against S. epidermidis Se-81, mechanism A and C against S. haemolyticus and mechanism A and B (active against nondividing bacteria and does not require protein and RNA synthesis) against the two S. aureus tested. Sparfloxacin showed mechanism A and C against the four Staphylococcus species studied, and temafloxacin was the only fluoroquinolone tested that exhibited mechanism A and B against the four bacterial strains assayed. No correlation was found between the in vitro bactericidal activity (expressed as minimum inhibitory concentration and optimal bactericidal concentration) and the mechanisms of action exhibited by these fluoroquinolones.

Clinical strains of Candida albicans express the surface antigen glyceraldehyde 3-phosphate dehydrogenase in vitro and in infected tissues

We have previously described the presence of an enzymatically active form of glyceraldehyde 3-phosphate-dehydrogenase (GAPDH) in the cell surface of Candida albicans ATCC 26555 which is also a fibronectin and laminin binding protein. Immunohistochemical analysis of tissue sections from patients with disseminated candidiasis with a polyclonal antiserum to GAPDH from C. albicans (PAb anti-CA-GAPDH) revealed that the enzyme is expressed at the surface of fungal cells in infected tissues. The same PAb detected the presence of GAPDH species, with a molecular mass of approximately 33 kDa, in cell wall extracts obtained from clinical isolates of the fungus. These cell surface-bound GAPDH moieties exhibited a dose-dependent dehydrogenase activity. These results indicate that this cell surface-bound GAPDH plays a role during infection probably contributing to the attachment of fungal cells to host tissues.

Evidence for the presence of complex carbohydrates in Candida albicans cell wall glycoproteins

In order to test the hypothesis that cell wall glycoproteins of Candida albicans contained non-mannan oligosaccharides, the sugar composition of cell wall extracts and fractions of cell wall extracts was examined by means of fluorophore-assisted carbohydrate electrophoresis (FACE). In addition to the expected mannose, glucose, and N-acetyl-glucosamine, this analysis showed the presence of galactose, N-acetyl-galactosamine, fucose, and sialic acid and two unknown sugars. These sugars are also associated with complex oligosaccharides of mammalian glycoproteins. Presence of fucosylated cell wall components was further demonstrated by lectin-blotting analysis of cell wall extracts. Besides their structural role, complex carbohydrate structures on the surface of C. albicans may represent additional motifs through which interactions of this fungus with host cells and tissues could be established.

Molecular cloning and characterization of a Candida albicans gene coding for cytochrome c haem lyase and a cell wall-related protein

Immunoscreening of a Candida albicans cDNA library with a monoclonal antibody (mAb 4C12) recognizing an epitope present in high-molecular-weight mannoprotein (HMWM) components specific for the mycelial cell walls (a 180 kDa component and a poly-dispersed 260 kDa species) resulted in the isolation of the gene CaCYC3 encoding for cytochrome c haem lyase (CCHL). The CaCYC3 gene was transcribed preferentially in mycelial cells in which two mRNA transcripts of 0.8 and 1 kb were found. The nucleotide and the deduced amino acid sequences of this gene displayed 45% homology and 46% identity, respectively, to the Saccharomyces cerevisiae CYC3 gene and shared common features with other reported genes encoding for CCHL. The CaCYC3 gene restored the respiratory activity when transformed in a S. cerevisiae cyc3- mutant strain. A C. albicans CYC3 null mutant was constructed after sequential disruption using the hisG::URA3::hisG ('ura-blaster') cassette. Null mutant cells were unable to use lactate as a sole carbon source and had a reduced ability to form germ tubes. Western immunoblotting analysis of subcellular fractions from wild-type and null mutant strains demonstrated the presence of two gene products, a 33kDa mitochondrial protein and a 40 kDa cell wall-associated moiety reacting with antibodies against CCHL, in both yeast cells and germ tubes. mAb 4C12 still reacted with the CaCYC3 null mutant (by immunofluorescence and immunoblotting) but showed an altered pattern of immunoreactivity against cell wall HMWM species, indicating a relationship between these moieties and the CaCYC3 gene products. The results suggest that the CaCYC3 gene encodes two proteins, one targeted to the mitochondria and the other to the cell wall.

Candida albicans fibrinogen binding mannoprotein: expression in clinical strains and immunogenicity in patients with candidiasis

A 58 kDa cell wall-associated fibrinogen binding mannoprotein (mp58), previously characterized by our group in a Candida albicans laboratory strain (ATCC 26555), was found to be also present in the cell wall of clinical isolates of this fungus. Most strains examined appear to have functional mp58 species, as detected by their ability to bind fibrinogen. Western immunoblot analysis, with a monovalent polyclonal antibody generated against the mp58 species from strain ATCC 26555, revealed differences in recognition patterns depending on the strain tested and the culture conditions used. Serum samples from normal and Candida infected individuals were examined for the presence of antibodies against mp58 by Western immunoblotting. None of the sera from control individuals and patients suffering from superficial candidiasis contained antibodies against mp58. However, positive reactivity with this antigen and other cell wall constituents was detected for all sera from patients with confirmed systemic candidiasis. Together, these results suggest that mp58 could play an active role during infection and may be useful as a specific antigenic marker for candidiasis.

The cell wall-associated glyceraldehyde-3-phosphate dehydrogenase of Candida albicans is also a fibronectin and laminin binding protein

By immunoelectron microscopy with a polyclonal antibody against the cytosolic glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from Candida albicans (anti-GAPDH PAb), the protein was clearly detected at the outer surface of the cell wall, particularly on blastoconidia, as well as in the cytoplasm. Intact blastoconidia were able to adhere to fibronectin and laminin immobilized on microtiter plates, and this adhesion was markedly reduced by both the anti-GAPDH PAb and soluble GAPDH from Saccharomyces cerevisiae. In addition, semiquantitative flow cytometry analysis with the anti-GAPDH PAb showed a decrease in antibody binding to cells in the presence of soluble fibronectin and laminin. Purified cytosolic C. albicans GAPDH was found to bind to fibronectin and laminin in a ligand Western blot assay. These observations suggest that the cell wall-associated form of the GAPDH in C. albicans could be involved in mediating adhesion of fungal cells to fibronectin and laminin, thus contributing to the attachment of the microorganism to host tissues and to the dissemination of Candida infection.

Cell wall and secreted proteins of Candida albicans: identification, function, and expression

The cell wall is essential to nearly every aspect of the biology and pathogenicity of Candida albicans. Although it was initially considered an almost inert cellular structure that protected the protoplast against osmotic offense, more recent studies have demonstrated that it is a dynamic organelle. The major components of the cell wall are glucan and chitin, which are associated with structural rigidity, and mannoproteins. The protein component, including both mannoprotein and nonmannoproteins, comprises some 40 or more moieties. Wall proteins may differ in their expression, secretion, or topological location within the wall structure. Proteins may be modified by glycosylation (primarily addition of mannose residues), phosphorylation, and ubiquitination. Among the secreted enzymes are those that are postulated to have substrates within the cell wall and those that find substrates in the extracellular environment. Cell wall proteins have been implicated in adhesion to host tissues and ligands. Fibrinogen, complement fragments, and several extracellular matrix components are among the host proteins bound by cell wall proteins. Proteins related to the hsp70 and hsp90 families of conserved stress proteins and some glycolytic enzyme proteins are also found in the cell wall, apparently as bona fide components. In addition, the expression of some proteins is associated with the morphological growth form of the fungus and may play a role in morphogenesis. Finally, surface mannoproteins are strong immunogens that trigger and modulate the host immune response during candidiasis.

Serologic response to cell wall mannoproteins and proteins of Candida albicans

The cell wall of Candida albicans not only is the structure in which many biological functions essential for the fungal cells reside but also is a significant source of candidal antigens. The major cell wall components that elicit a response from the host immune system are proteins and glycoproteins, the latter being predominantly mannoproteins. Both the carbohydrate and protein moieties are able to trigger immune responses. Although cell-mediated immunity is often considered to be the most important line of defense against candidiasis, cell wall protein and glycoprotein components also elicit a potent humoral response from the host that may include some protective antibodies. Proteins and glycoproteins exposed at the most external layers of the wall structure are involved in several types of interactions of fungal cells with the exocellular environment. Thus, coating of fungal cells with host antibodies has the potential to influence profoundly the host-parasite interaction by affecting antibody-mediated functions such as opsonin-enhanced phagocytosis and blocking the binding activity of fungal adhesins for host ligands. In this review, the various members of the protein and glycoprotein fraction of the C. albicans cell wall that elicit an antibody response in vivo are examined. Although a number of proteins have been shown to stimulate an antibody response, for some of these species the response is not universal. On the other hand, some of the studies demonstrate that certain cell wall antigens and anti-cell wall antibodies may be the basis for developing specific and sensitive serologic tests for the diagnosis of candidasis, particularly the disseminated form. In addition, recent studies have focused on the potential for antibodies to cell wall protein determinants to protect the host against infection. Hence, a better understanding of the humoral response to cell wall antigens of C. albicans may provide the basis for the development of (i) effective procedures for the serodiagnosis of disseminated candidiasis and (ii) novel prophylactic (vaccination) and therapeutic strategies for the management of this type of infection.

Cloning of a cDNA fragment encoding part of the protein moiety of the 58-kDa fibrinogen-binding mannoprotein of Candida albicans

Immunoscreening of a Candida albicans expression library with antibodies against the 58 kDa fibrinogen-binding mannoprotein (mp58) of the fungus resulted in the isolation of clones encoding the protein moiety of this molecule. Sequence of the 0.9 kb cDNA of one of the clones selected for further analysis, revealed an open reading frame coding for 292 amino acids, which displays sequence similarity to proteins belonging to a family of immunodominant antigens of Aspergillus spp. The gene corresponding to this cDNA was named FBP1 (fibrinogen-binding protein). These results represent the first report on the identification of C. albicans genes encoding surface receptors for host proteins.

Hemin induces germ tube formation in Candida albicans

Hemin induced germination of Candida albicans blastoconidia when cells grown up to the early exponential phase were shifted from 28 to 37 degrees C (70 to 75% of cells exhibited germ tubes). N-Acetyl-D-glucosamine (GlcNAc), another inducer of myceliation in this fungus, caused a similar effect. The combination of hemin and GlcNAc resulted in a higher percentage (95%) of blastoconidial germination. These results suggest that in addition to temperature, hemin levels and carbon source may coordinately regulate the expression of subsets of genes involved in the yeast-to-mycelium transition in C. albicans.

The glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase of Candida albicans is a surface antigen

A lambda gt11 cDNA library from Candida albicans ATCC 26555 was screened by using pooled sera from two patients with systemic candidiasis and five neutropenic patients with high levels of anti-C. albicans immunoglobulin M antibodies. Seven clones were isolated from 60,000 recombinant phages. The most reactive one contained a 0.9-kb cDNA encoding a polypeptide immunoreactive only with sera from patients with systemic candidiasis. The whole gene was isolated from a genomic library by using the cDNA as a probe. The nucleotide sequence of the coding region showed homology (78 to 79%) to the Saccharomyces cerevisiae TDH1 to TDH3 genes coding for glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and their amino acid sequences showed 76% identity; thus, this gene has been named C. albicans TDH1. A rabbit polyclonal antiserum against the purified cytosolic C. albicans GAPDH (polyclonal antibody [PAb] anti-CA-GAPDH) was used to identify the GAPDH in the beta-mercaptoethanol extracts containing cell wall moieties. Indirect immunofluorescence demonstrated the presence of GAPDH at the C. albicans cell surface, particularly on the blastoconidia. Semiquantitative flow cytometry analysis showed the sensitivity of this GAPDH form to trypsin and its resistance to be removed with 2 M NaCl or 2% sodium dodecyl sulfate. The decrease in fluorescence in the presence of soluble GAPDH indicates the specificity of the labelling. In addition, a dose-dependent GAPDH enzymatic activity was detected in intact blastoconidia and germ tube cells. This activity was reduced by pretreatment of the cells with trypsin, formaldehyde, and PAb anti-CA-GAPDH. These observations indicate that an immunogenic, enzymatically active cell wall-associated form of the glycolytic enzyme GAPDH is found at the cell surface of C. albicans cells.

Molecular cloning and characterization of a Candida albicans gene (EFB1) coding for the elongation factor EF-1 beta

A Candida albicans gene homologous to Saccharomyces cerevisiae elongation factor 1 beta was isolated by screening a genomic DNA library using a C. albicans cDNA as a probe. This cDNA was previously obtained by immunoscreening of an expression library with polyclonal antibodies raised against candidal cell wall components. Sequence analysis of the cDNA and the whole C. albicans gene (EMBL accession number X96517) revealed an intron-interrupted open reading frame of 639 base pairs that encodes a 213 amino acid protein. Exon sequences are highly homologous (74%) to S. cerevisiae EFB1, whereas intron sequence is less conserved (34% identity), and the predicted amino acid sequence shares about 73% identity.

Expression of the fibrinogen binding mannoprotein and the laminin receptor of Candida albicans in vitro and in infected tissues

We have previously reported a 37 kDa laminin-binding protein (p37) and a 58 kDa fibrinogen-binding mannoprotein (mp58) on the surface of Candida albicans. A few yeast cells expressed both functional receptors at the surface while germ tubes expressed a functional mp58 fibrinogen but not a functional p37 laminin receptor. These receptors were heterogeneously dispersed at the surface as shown by binding of rabbit antiserum to mp58 (PAb anti-mp58) and antiserum to the human high affinity laminin receptor. In this report we have used a dual fluorescence technique to determine if the two receptors colocalize, perhaps as part of a receptor complex. Fibrinogen was used as a probe for mp58 and polyclonal antiserum generated to the p37 (PAb anti-p37) was used as a probe for the 37 kDa laminin-binding protein. Both receptors were heterogeneously distributed, but the receptors were not colocalized as the areas of concentration of each receptor were different. Immunohistochemical analysis of tissue sections from patients with disseminated and superficial candidiasis with PAb anti-p37 and PAb anti-mp58 revealed that both receptors were also expressed in infected tissues. The patterns of morphological expression were similar to the in vitro patterns detected by immunofluorescence.

Cell wall protein and glycoprotein constituents of Aspergillus fumigatus that bind to polystyrene may be responsible for the cell surface hydrophobicity of the mycelium

Cell surface hydrophobicity (CSH) of Aspergillus fumigatus grown both in complex medium (yeast extract/peptone/dextrose; YPD) and minimal (Vogel's N) medium was monitored by assessing attachment of polystyrene microspheres to the cell surface. It was found that mature mycelium was hydrophobic. Treatment of intact mycelium with beta-mercaptoethanol (beta ME) abolished binding of the microspheres to hyphal elements, and coating of the microspheres with beta ME extracts from mycelium inhibited their attachment to intact mycelial cells. A. fumigatus mycelium was tagged in vivo with biotin and treated with beta ME. The beta ME extracts were analysed by SDS-PAGE and Western blotting with both peroxidase-conjugated-ExtrAvidin and concanavalin A (ConA). This procedure allowed identification of cell wall surface proteins and glycoproteins. Rabbit polyclonal antisera were raised against beta ME extracts obtained from cells grown in YPD and Vogel's N media. These antisera defined some major cell-wall-bound antigens. SDS-PAGE and Western blotting analysis of the cell wall material released by beta ME and adsorbed on polystyrene microspheres revealed about 19 protein species with apparent molecular masses ranging from 20 to 70 kDa, and two high-molecular-mass glycoproteins of 115 and 210 kDa. Treatment of cells grown in YPD, but not those grown in Vogel's N medium, with beta ME released a 55 kDa polypeptide able to adsorb to polystyrene microspheres that was detectable with the antisera. The ability to bind to polystyrene particles exhibited by several protein and glycoprotein species released by beta ME treatment suggested that these cell wall moieties possess exposed hydrophobic domains that could be responsible for the CSH of mycelium.

Preliminary characterization of the material released to the culture medium by Candida albicans yeast and mycelial cells

Culture filtrate concentrates were obtained from Candida albicans yeast and mycelial cells grown in the presence of 14C-protein hydrolysate for radioactive labeling of cellular polypeptides. Both growth forms released to the medium minor but significant amounts of proteinaceous materials. The analysis of culture filtrate concentrates by means of SDS-polyacrylamide gel electrophoresis and fluorography revealed a similar and complex electrophoretic pattern, though some qualitative and quantitative differences between samples obtained from yeast and mycelial cells were observed. Materials released, mostly composed of mannoproteins as shown by their affinity towards concanavalin A, presented (i) cross-reactivity (by Western immunoblotting and ELISA) against polyclonal antisera to genuine cell wall components (among them the 58-kilodalton fibrinogen-binding mannoprotein) and (ii) high affinity for polystyrene-latex microbeads. Results presented suggest a possible common identity for the molecules shed to the medium and the cell wall protein and mannoprotein constituents.

Evidence for the presence of collagenous domains in Candida albicans cell surface proteins

Rabbit polyclonal antibodies (PAbs) directed towards the amino-terminal cysteine-rich 7S domain (PAb anti-7S), the major internal collagenous domain (PAb anti-type IV), and the C-terminal noncollagenous region (PAb anti-NC1) of the type IV collagen molecule were probed by indirect immunofluorescence against Candida albicans blastoconidia and germinated blastoconidia. Most nongerminating cells and mother blastoconidia from which germ tubes originated showed strong fluorescence when PAb anti-7S was used, whereas with PAb anti-type IV, fluorescence was found almost exclusively on the surface of filamentous forms. A patched fluorescent pattern rather than a homogenous confluent fluorescence was observed in all cases. No fluorescent cells were observed with PAb anti-NC1. By Western immunoblotting, PAb anti-type IV cross-reacted primarily with a polypeptide of 37 kDa present in wall extracts obtained from intact cells of both growth forms by treatment with beta-mercaptoethanol, whereas PAb anti-7S recognized a major 58-kDa antigen also present in both extracts, along with some other high-molecular-mass (> 106-kDa) polydisperse species present only in the material released from blastoconidia with beta-mercaptoethanol. No reactive bands were observed when PAb anti-NC1 was used as a probe in Western immunoblotting experiments. The sensitivities or resistances to collagenase digestion of the different polypeptides that cross-reacted with PAbs anti-type IV and anti-7S suggest the existence of cell wall components in C. albicans that contain epitopes that mimic the collagenous domains of the type IV collagen molecule.

Comparative study of the C3d receptor and 58-kilodalton fibrinogen-binding mannoproteins of Candida albicans

Using polyclonal antibodies (PAbs) raised against the Candida albicans C3d receptor (CR2; PAb anti-CR2) and the 58-kDa fibrinogen-binding mannoprotein (mp58; PAb anti-mp58) as well as ligand interactions, we have studied the relationship between these two receptors. In an indirect immunofluorescence assay with germ tubes, greater intensity was observed on the mother blastoconidium when PAb anti-CR2 was used, whereas greater intensity was localized to the hyphal extension when PAb anti-mp58 or binding of soluble fibrinogen was used. No competition or change in the fluorescence pattern was observed in dual-labeling experiments with PAb anti-CR2 and either fibrinogen or PAb anti-mp58. Binding competition also was not observed in an enzyme-linked immunosorbent assay using the components present in a beta-mercaptoethanol extract from the cell wall of germ tubes. In immunoblots, PAb anti-CR2 recognized three different discrete bands with apparent molecular masses of 21, 40, and 66 kDa in the beta-mercaptoethanol extracts from the cell wall, whereas a different, single, broader band with an apparent molecular mass of 58 kDa was detected with PAb anti-mp58. However, when nondenaturing conditions were used to separate the materials present in the cell wall extracts, no reactivity could be detected on Western blots (immunoblots) with PAb anti-mp58. When PAb anti-CR2 was used for analysis, a single band migrating in the area corresponding to approximately 40 kDa was detected. These observations suggest a higher molecular weight for mp58 and one or more of the components detected with PAb anti-CR2 in their native state.

Chitin synthetases in Candida albicans: a review on their subcellular distribution and biological function

In the light of recent genetic advances, some results regarding chitin biosynthetic activities are reviewed in this paper. Genes coding for distinct enzymes displaying chitin synthetase activities have been characterized in Saccharomyces cerevisiae as well as in other fungal species including Candida albicans. Several activities seem to exist in the cells: (i) one zymogenic, located in cytoplasmic vesicles called chitosomes, although the presence of other types of vesicles with zymogenic activity cannot be completely discarded, and (ii) plasma membrane associated activities (the active enzyme and probably two distinct pools of zymogenic activity). Possible relationships between these activities, if any, remain to be determined. These multiplicity of enzymes is not surprising taking into account that chitin biosynthesis is required during very well defined temporal and spatial events of the cell cycle. A general repair function for one of the chitin biosynthetic activities is proposed as a possible salvage mechanism to warrant cell survival after wall damage has been caused, since chitin appears to be the most suitable polymer to carry out this function due to its particular physico-chemical properties.

Changes in the cell wall glycoprotein composition of Candida albicans associated to the inhibition of germ tube formation by EDTA

Hyphal development in Candida albicans was blocked by EDTA. This effect was not due to a general growth inhibition since the chelator did not affect protein and DNA synthesis. Recovery of mycelial growth was observed when EDTA-grown cells were incubated at 37 degrees C in EDTA-free medium. High-molecular-weight mannoproteins (HMWM) that are mycelium-specific wall components, and particularly a 260-kDa species (HMWM-260), were absent in the wall of cells grown under germination conditions in the presence of EDTA. Synthesis of the HMWM-260 species was not inhibited but its incorporation (secretion) into the wall structure seemed to be blocked in EDTA-treated cells.

Heterogeneous surface distribution of the fibrinogen-binding protein on Candida albicans

As detected by indirect immunofluorescence and confocal microscopy, fibrinogen binding was heterogeneously distributed on the surface of Candida albicans. A low level of binding was generally observed homogeneously distributed on some yeast and most hyphal extensions of germ tubes. However, on most hyphal extensions, there were randomly distributed areas of increased expression, as revealed by patches of greater fluorescence intensity.

Evidence for the presence of a high-affinity laminin receptor-like molecule on the surface of Candida albicans yeast cells

Two polypeptides of 37 and 67 kDa that bind laminin were detected in cell wall extracts of Candida albicans blastoconidia. The 37-kDa species, found only in yeast cell wall extracts, cross-reacted with a rabbit polyclonal antibody (PAb 4160) directed towards the carboxyl-terminal laminin-binding domain present in the human 67-kDa high-affinity laminin receptor (67LR) and its 37-kDa precursor (37LRP), whereas another antibody (PAb 4056), directed against internal domains of 67LR and 37LRP, recognized a 37-kDa species in wall extracts from both blastoconidia and germinated blastoconidia. Indirect immunofluorescence with PAb 4160 showed a patchy binding pattern only on yeast cells that represented about 10% of the entire blastoconidia population.

Diagnosis of systemic candidiasis by enzyme immunoassay detection of specific antibodies to mycelial phase cell wall and cytoplasmic candidal antigens

Diagnosis of systemic Candida infections was attempted by the use of an enzyme-linked immunosorbent assay (EIA) to detect IgG antibodies towards cell wall-bound and cytoplasmic candidal antigens. Cell wall antigens were sequentially solubilized by treatment of germinated blastoconidia of Candida albicans (ATCC 26555 strain) with beta-mercaptoethanol (beta ME extract) and digestion with Zymolyase 20T, a beta-glucanase preparation (Zymolyase extract). Protoplasts obtained after treatment with Zymolyase were osmotically lysed (cytoplasmic antigens). Sera were obtained from patients with systemic (n = 28) and superficial (n = 46) candidiasis. Control sera were obtained from normal healthy individuals (n = 31) and from hospitalized patients at low (n = 36) and at high (n = 13) risk of developing systemic candidiasis yet showing no symptoms of candidal infection. Detection of antibodies in crude sera samples by EIA using all of these antigenic extracts was highly specific (98-100%), but sensitivity of the method was low (3.5-17.8%). However, adsorption of sera with latex microspheres coated with purified Candida mannan in order to selectively remove anti-mannan antibodies prior to EIA improved the diagnostic efficiency of this test. Improvement was particularly noticeable when the beta ME extract was used as antigenic preparation, yielding a sensitivity of 89.2% and a specificity of 98.6%.

Are there salvage routes within the general secretory pathway in yeast?

It is generally accepted that both extracellular protein secretion and plasma membrane expansion in yeast occur basically as in higher eukaryotic cells. In addition to the constitutive (default) secretory pathway, some specialized mammalian cells possess a regulated route which at present has not been detected in yeast. However, there is a body of experimental results suggesting that under certain circumstances export of integral plasma membrane and exocellular proteins may take place through alternative (salvage) pathways. The existence of these latter routes would enable the yeast cell to adapt more efficiently to distinct or adverse conditions requiring the secretion of discrete amounts of specific sets of proteins.

Stability of chitin synthetase in cell-free preparations of a wild-type strain and a 'slime' variant of Neurospora crassa

Chitin synthetase activity in cell-free preparations from a wild-type strain and a 'slime' variant of Neurospora crassa was monitored over many days in samples stored at 0 degrees C. Total activity in whole-cell-free extracts and low-speed supernatants from both organisms was very unstable, losing more than 90% of the initial activity on storage at 0 degrees C for 96 h. Chitin synthetase detection was not masked by chitinase activity present in the preparations. Gel-filtration chromatography of these preparations increased the stability of the activity from the 'slime' variant, whereas removal of particulate structures by high-speed centrifugation stabilized the chitin synthetase activity in the supernatant, particularly in the wild type. These results suggest that factor(s) involved in the regulation of chitin synthetase may be differentially located or altered in 'slime' cells.

Antigenic cell wall mannoproteins in Candida albicans isolates and in other Candida species

Polyclonal antibodies (pAbs) and monoclonal antibodies (mAbs), raised against mannoprotein components from Candida albicans ATCC 26555 (serotype A) blastoconidia and mycelial cell walls, were used to investigate antigenic similarities among wall mannoproteins from other C. albicans serotype A and B strains, and from C. tropicalis and C. guilliermondii. Radioactively labelled walls isolated from cells grown at either 28 degrees C or 37 degrees C were digested with a beta-glucanase complex (Zymolyase 20T) to release cell-wall-bound mannoproteins. Numerous molecular species with different electrophoretic mobilities were released from the various isolates. Differences appeared to be related to both the organism and the growth temperature. Among the major protein components solubilized were mannoproteins larger than 100 kDa (high molecular mass mannoproteins), heterogeneous in size in most cases. Antigenic homology was detected among the cell wall high molecular mass mannoproteins of the two C. albicans serotype A isolates, whereas significant qualitative and quantitative differences were detected between serotype A and serotype B cell-wall-bound antigenic profiles. Moreover, C. tropicalis and C. guilliermondii wall antigenic determinants were not recognized by the preparations of pAbs and mAbs raised against C. albicans walls. A mannoprotein with a molecular mass of 33-34 kDa was present in the enzymic wall digests of all the organisms studied. When probed with pAbs raised against the protein moiety of the 33 kDa cell wall mannoprotein of Saccharomyces cerevisiae, antigenic cross-reactivity was observed in all cases except C. tropicalis. There appear to be significant antigenic differences between the mannoproteins of different isolates of C. albicans, and between those of C. albicans and other Candida species.

Fab fragments from a monoclonal antibody against a germ tube mannoprotein block the yeast-to-mycelium transition in Candida albicans

Fab fragments prepared from the immunoglobulin G monoclonal antibody (MAb) 4C12, which reacts with a determinant expressed on the hyphal extension of germ tubes of Candida albicans, inhibited germ tube formation, but intact MAb 4C12 did not. Indirect immunofluorescence showed a punctate binding pattern on cells incubated with Fab fragments but a confluent binding on cells incubated with intact MAb 4C12.

Sedimentation properties of chitosomal chitin synthetase from the wild-type strain and the 'slime' variant of Neurospora crassa

Marked differences in the pattern of sedimentation of cellular structures were observed after isopycnic centrifugation of crude cell-free preparations from the Neurospora crassa wall-less 'slime' variant and mycelial wild-type strain. Kinetic studies of particle sedimentation showed that the various types of subcellular components, as revealed by turbidity, UV absorption, polypeptide patterns, and chitin synthetase activity determinations, sediment independently of one another. An important feature was the finding that chitin synthetase from 'slime' peaked at a median specific gravity of 1.1201 +/- 0.0036, whereas that from wild-type strain sedimented at a higher buoyant density (specific gravity 1.1349 +/- 0.0024). Different cultivation conditions or cell breakage procedures (osmotic lysis or ballistic disruption) did not seem to affect this sedimentation behavior. Electron microscopy revealed the presence of chitosomes (microvesicles containing chitin synthetase) in the chitin synthetase activity peaks obtained after isopycnic centrifugation of cell-free extracts from 'slime' and wild-type strains. The discrepancy in buoyant density of chitin synthetases from both N. crassa strains might point to inherent differences in chemical composition of the chitosomal microvesicles. In any case, the lower buoyant density of 'slime' chitosomes appears to be one of several major alterations in sedimentation behavior of subcellular structures. These alterations might be related to the inability of 'slime' to make a cell wall.

Subcellular fractionation of actively growing protoplasts of Saccharomyces cerevisiae

Cell homogenates obtained from partially regenerated Saccharomyces cerevisiae protoplasts were fractionated by a procedure using a combination of continuous and discontinuous sucrose gradients, under experimental conditions that minimize possible artifacts due to centrifugation and resuspension. At least five different membranous organelle fractions (plasma membrane, mitochondria, rough endoplasmic reticulum, smooth endoplasmic reticulum-like structures and small-sized particulated structures) were isolated. Subcellular fractions were characterized by assaying established marker enzymes. Radioactive labelled [(U-3H]uracil) ribosomes were also used as a further characterization criterion of the rough endoplasmic reticulum. Comparative SDS-polyacrylamide gel electrophoresis of the protein constituents of the isolated membrane-bound organelles suggest that the polypeptide pattern could also be used as an additional marker for some of these structures. Finally, subcellular distribution of chitin synthase was determined using this fractionation procedure, and two partially zymogenic enzyme pools (one inside the cell associated to particles which sediments at high speed, and the second one associated to the plasma membrane) were found.

Abnormal septal motion in cardiac tamponande with pulse paradoxus. Echocardiographic and hemodynamic observations

In a patient with cardiac tamponade and pulses paradoxus the echocardiogram showed markedly abnormal septal motion, consisting of posterior displacement during inspiration. This displacement resulted from an increase in right ventricular size and a decrease in left ventricular volume, not attributable to a change in position of the heart. The correlation of this finding with hemodynamic events showed that the inspiratory drop in arterial pressure followed septal displacement. These observations support the hypothesis that pulsus paradoxus may be caused by competition of the ventricles for filling within a relatively rigid pericardial space. Displacement of the interventricular septum could be the mechanism by which this completition takes place.