The Association Between Sexual Functioning and Suicide Risk in U.S. Military Veteran Couples Seeking Treatment for Post-Traumatic Stress Disorder.

Intimate relationship distress has been identified as one of the most common precipitants of suicidal thoughts for U.S. military populations. Sexual functioning is associated with relationship distress and has recently been identified as a predictor of suicidal ideation with female military personnel; however, no studies have examined this association among a treatment-seeking sample of male and female veterans and their partners. Couples (N = 138) completed baseline assessments of sexual functioning, relationship functioning, suicidal ideation, and mental health prior to evaluation for engagement in a couples-based PTSD treatment study. Analyses revealed that decreased sexual pleasure and decreased frequency of sexual intercourse were associated with more recent suicidal ideation for male veterans, whereas increased sexual frequency was marginally associated with increased suicidal ideation for female veterans, controlling for PTSD and depression symptoms, relationship satisfaction, and medications. These findings stress the importance of assessing sexual functioning as a risk factor for suicide and taking into consideration the possibility that sexual functioning may be protective or predictive of suicidality depending on the person and context.

Examination of the pathogenic potential of Candida albicans filamentous cells in an animal model of haematogenously disseminated candidiasis.

The opportunistic fungal pathogen Candida albicans is an increasingly common threat to human health. Candida albicans grows in several morphologies and mutant strains locked in yeast or filamentous forms have attenuated virulence in the murine model of disseminated candidiasis. Thus, the ability to change shape is important for virulence. The transcriptional repressors Nrg1p and Tup1p are required for normal regulation of C. albicans morphology. Strains lacking either NRG1 or TUP1 are constitutively pseudohyphal under yeast growth conditions, and display attenuated virulence in the disseminated model. To dissect the relative importance of hyphae and pseudohyphae during an infection, we used strains in which the morphological transition could be externally manipulated through controlled expression of NRG1 or TUP1. Remarkably, hyphal form inocula retain the capacity to cause disease. Whilst induction of a pseudohyphal morphology through depletion of TUP1 did result in attenuated virulence, this was not due to a defect in the ability to escape the bloodstream. Instead, we observed that pseudohyphal cells are cleared from tissues much more efficiently than either hyphal (virulent) or yeast form (avirulent) cells, indicating that different C. albicans morphologies have distinct interactions with host cells during an infection.

Evolution of the derivative skewness for nonlinearly propagating waves.

The skewness of the first time derivative of a pressure waveform, or derivative skewness, has been used previously to describe the presence of shock-like content in jet and rocket noise. Despite its use, a quantitative understanding of derivative skewness values has been lacking. In this paper, the derivative skewness for nonlinearly propagating waves is investigated using analytical, numerical, and experimental methods. Analytical expressions for the derivative skewness of an initially sinusoidal plane wave are developed and, along with numerical data, are used to describe its behavior in the preshock, sawtooth, and old-age regions. Analyses of common measurement issues show that the derivative skewness is relatively sensitive to the effects of a smaller sampling rate, but less sensitive to the presence of additive noise. In addition, the derivative skewness of nonlinearly propagating noise is found to reach greater values over a shorter length scale relative to sinusoidal signals. A minimum sampling rate is recommended for sinusoidal signals to accurately estimate derivative skewness values up to five, which serves as an approximate threshold indicating significant shock formation.

Phase and amplitude gradient method for the estimation of acoustic vector quantities.

An alternative pressure-sensor based method for estimating the acoustic intensity, the phase and amplitude gradient estimation (PAGE) method, is presented. This method uses the same hardware as the standard finite-difference method, but does not suffer from the frequency-dependent bias inherent to the finite-difference method. A detailed derivation of the PAGE method and the finite-difference method is presented. Both methods are then compared using simple acoustic fields. The ability to unwrap the phase component of the PAGE method is discussed, which leads to accurate intensity estimates above previous frequency limits. The uncertainties associated with both methods of estimation are presented. It is shown that the PAGE method provides more accurate intensity estimates over a larger frequency bandwidth.

Evolution of the average steepening factor for nonlinearly propagating waves.

Difficulties arise in attempting to discern the effects of nonlinearity in near-field jet-noise measurements due to the complicated source structure of high-velocity jets. This article describes a measure that may be used to help quantify the effects of nonlinearity on waveform propagation. This measure, called the average steepening factor (ASF), is the ratio of the average positive slope in a time waveform to the average negative slope. The ASF is the inverse of the wave steepening factor defined originally by Gallagher [AIAA Paper No. 82-0416 (1982)]. An analytical description of the ASF evolution is given for benchmark cases-initially sinusoidal plane waves propagating through lossless and thermoviscous media. The effects of finite sampling rates and measurement noise on ASF estimation from measured waveforms are discussed. The evolution of initially broadband Gaussian noise and signals propagating in media with realistic absorption are described using numerical and experimental methods. The ASF is found to be relatively sensitive to measurement noise but is a relatively robust measure for limited sampling rates. The ASF is found to increase more slowly for initially Gaussian noise signals than for initially sinusoidal signals of the same level, indicating the average distortion within noise waveforms occur more slowly.

Time-domain effects of rigid sphere scattering on measurement of transient plane waves.

Transient waves, like all other acoustic waves, will diffract around solid objects, such as measurement instrumentation. A derivation of an impulse response function on the surface of a rigid sphere, based on linear, classical scattering theory, is presented. The theoretical impulse response function is validated using an experiment with blast noise. An application of the impulse response function to a rocket noise measurement is discussed. The impulse response function shows that the presence of the rigid sphere significantly affects the measurement and estimation of rocket-noise waveforms, power spectral densities, and statistical measures.

BRG1 and NRG1 form a novel feedback circuit regulating Candida albicans hypha formation and virulence.

In the opportunistic fungal pathogen Candida albicans both cellular morphology and the capacity to cause disease are regulated by the transcriptional repressor Nrg1p. One of the genes repressed by Nrg1p is BRG1, which encodes a putative GATA family transcription factor. Deletion of both copies of this gene prevents hypha formation. We discovered that BRG1 overexpression is sufficient to overcome Nrg1p-mediated repression and drive the morphogenetic shift from yeast to hyphae even in the absence of environmental stimuli. We further observed that expression of BRG1 influences the stability of the NRG1 transcript, thus controlling filamentation through a feedback loop. Analysis of this phenomenon revealed that BRG1 expression is required for the induction of an antisense NRG1 transcript. This is the first demonstration of a role for mRNA stability in regulating the key C. albicans virulence trait: the ability to form hyphae.

Anaerobic conditions are a major influence on Candida albicans chlamydospore formation.

Candidiasis now represents the fourth most frequent nosocomial infection both in the USA and worldwide. Candida albicans is an increasingly common threat to human health as a consequence of AIDS, steroid therapy, organ and tissue transplantation, cancer therapy, broad-spectrum antibiotics, and other immune defects. Unfortunately, these infections carry unacceptably high morbidity, mortality rates and important economic repercussions (estimated total direct cost of approximately 2 billion dollars in 1998 in US hospitals alone). This pathogen can grow both in yeast and filamentous forms and the pathogenic potential of C. albicans is intimately related to certain key processes including filamentation. Chlamydospores are considered to be a dormant form of C. albicans that remain understudied. Chlamydospores have been widely used as a diagnostic tool to separate C. albicans and C. dubliniensis from other Candida species. More recently, media have been developed that use chlamydopsore formation to separate C. albicans and C. dubliniensis from each other. Chlamydospore formation can be stimulated by hypoxic conditions but only on limited specific media types. Here, we show that anaerobic conditions are enough to drive chlamydospore formation in C. albicans on the surface of nutrient-rich agar.

Examining the effects of BRG1 over-expression on Candida albicans strains growing as pseudohyphae.

The pathogen Candida albicans is pleiomorphic and grows in yeast and filamentous forms but the relationship between the regulation of different filamentous forms is unclear. BRG1 encodes a DNA binding protein which is an important regulator of morphology. Mutants lacking BRG1 grow as yeast under all conditions tested and over-expressing BRG1 drives hyphal growth even in the absence of inducing signals. A number of genetic mutants in repressors of filamentation form pseudohyphae under yeast conditions and some of these mutants can form hyphae under hypha-inducing conditions. This study examines the position of BRG1 in the regulatory networks that govern filamentation by examining the effect of over-expressing BRG1 in pseudohyphal mutants.

Constitutive ALS3 expression in Candida albicans enhances adhesion and biofilm formation of efg1, but not cph1 mutant strains.

Adhesion to living and non-living surfaces is an important virulence trait of the fungal pathogen Candida albicans. Biofilm formation in this organism depends on the expression of a number of cell surface proteins including the hypha-specific protein Als3p. Loss of ALS3 impairs biofilm formation and decreases cell-cell adhesion. We wanted to test whether constitutively expressing ALS3 could compensate for defects in adhesion and biofilm formation observed in mutant strains that lack key transcriptional regulators of biofilm formation Efg1p and Cph1p. We found that ALS3 improved adhesion and biofilm formation in the efg1Δ and efg1Δ cph1Δ mutant strains, but had less effect on the cph1Δ strain.

Candida albicans adhesin Als3p is dispensable for virulence in the mouse model of disseminated candidiasis.

The presence of specific proteins, including Ece1p, Hwp1p and Als3p, distinguishes the Candida albicans hyphal cell wall from that of yeast-form cells. These proteins are thought to be important for the ability of C. albicans cells to adhere to living and non-living surfaces and for the cell-to-cell adhesion necessary for biofilm formation, and also to be pivotal in mediating C. albicans interactions with endothelial cells. Using an in vitro flow adhesion assay, we previously observed that yeast cells bind in greater numbers to human microvascular endothelial cells than do hyphal or pseudohyphal cells. This is consistent with previous observations that, in a murine model of disseminated candidiasis, cells locked in the yeast form can efficiently escape the bloodstream and invade host tissues. To more precisely explore the role of Als3p in adhesion and virulence, we deleted both copies of ALS3 in a wild-type C. albicans strain. In agreement with previous studies, our als3Δ null strain formed hyphae normally but was defective in biofilm formation. Whilst ALS3 was not expressed in our null strain, hypha-specific genes such as ECE1 and HWP1 were still induced appropriately. Both the yeast form and the hyphal form of the als3Δ strain adhered to microvascular endothelial cells to the same extent as a wild-type strain under conditions of flow, indicating that Als3p is not a significant mediator of the initial interaction between fungal cells and the endothelium. Finally, in a murine model of haematogenously disseminated candidiasis the mutant als3Δ remained as virulent as the wild-type parent strain.

The transcriptional regulator Nrg1p controls Candida albicans biofilm formation and dispersion.

The ability of Candida albicans to reversibly switch morphologies is important for biofilm formation and dispersion. In this pathogen, Nrg1p functions as a key negative regulator of the yeast-to-hypha morphogenetic transition. We have previously described a genetically engineered C. albicans tet-NRG1 strain in which NRG1 expression levels can be manipulated by the presence or absence of doxycycline (DOX). Here, we have used this strain to ascertain the role of Nrg1p in regulating the different stages of the C. albicans biofilm developmental cycle. In an in vitro model of biofilm formation, the C. albicans tet-NRG1 strain was able to form mature biofilms only when DOX was present in the medium, but not in the absence of DOX, when high levels of NRG1 expression blocked the yeast-to-hypha transition. However, in a biofilm cell retention assay in which biofilms were developed with mixtures of C. albicans tet-NRG1 and SC5314 strains, tet-NRG1 yeast cells were still incorporated into the mixed biofilms, in which an intricate network of hyphae of the wild-type strain provided for biofilm structural integrity and adhesive interactions. Also, utilizing an in vitro biofilm model under conditions of flow, we demonstrated that C. albicans Nrg1p exerts an exquisite control of the dispersal process, as overexpression of NRG1 leads to increases in dispersion of yeast cells from the biofilms. Our results demonstrate that manipulation of NRG1 gene expression has a profound influence on biofilm formation and biofilm dispersal, thus identifying Nrg1p as a key regulator of the C. albicans biofilm life cycle.

Pseudohyphal regulation by the transcription factor Rfg1p in Candida albicans.

The opportunistic human fungal pathogen Candida albicans is a major cause of nosocomial infections. One of the fundamental features of C. albicans pathogenesis is the yeast-to-hypha transition. Hypha formation is controlled positively by transcription factors such as Efg1p and Cph1p, which are required for hyphal growth, and negatively by Tup1p, Rfg1p, and Nrg1p. Previous work by our group has shown that modulating NRG1 gene expression, hence altering morphology, is intimately linked to the capacity of C. albicans to cause disease. To further dissect these virulence mechanisms, we employed the same strategy to analyze the role of Rfg1p in filamentation and virulence. Studies using a tet-RFG1 strain revealed that RFG1 overexpression does not inhibit hypha formation in vitro or in the mouse model of hematogenously disseminated candidiasis. Interestingly, RFG1 overexpression drives formation of pseudohyphae under yeast growth conditions-a phenotype similar to that of C. albicans strains with mutations in one of several mitotic regulatory genes. Complementation assays and real-time PCR analysis indicate that, although the morphology of the tet-RFG1 strain resembles that of the mitotic regulator mutants, Rfg1p overexpression does not impact expression of these genes.

The sigmaR regulon of Streptomyces coelicolor A32 reveals a key role in protein quality control during disulphide stress.

Diamide is an artificial disulphide-generating electrophile that mimics an oxidative shift in the cellular thiol-disulphide redox state (disulphide stress). The Gram-positive bacterium Streptomyces coelicolor senses and responds to disulphide stress through the sigma(R)-RsrA system, which comprises an extracytoplasmic function (ECF) sigma factor and a redox-active anti-sigma factor. Known targets that aid in the protection and recovery from disulphide stress include the thioredoxin system and genes involved in producing the major thiol buffer mycothiol. Here we determine the global response to diamide in wild-type and sigR mutant backgrounds to understand the role of sigma(R) in this response and to reveal additional regulatory pathways that allow cells to cope with disulphide stress. In addition to thiol oxidation, diamide was found to cause protein misfolding and aggregation, which elicited the induction of the HspR heat-shock regulon. Although this response is sigma(R)-independent, sigma(R) does directly control Clp and Lon ATP-dependent AAA(+) proteases, which may partly explain the reduced ability of a sigR mutant to resolubilize protein aggregates. sigma(R) also controls msrA and msrB methionine sulphoxide reductase genes, implying that sigma(R)-RsrA is responsible for the maintenance of both cysteine and methionine residues during oxidative stress. This work shows that the sigma(R)-RsrA system plays a more significant role in protein quality control than previously realized, and emphasizes the importance of controlling the cellular thiol-disulphide redox balance.

Presence of extracellular DNA in the Candida albicans biofilm matrix and its contribution to biofilms.

DNA has been described as a structural component of the extracellular matrix (ECM) in bacterial biofilms. In Candida albicans, there is a scarce knowledge concerning the contribution of extracellular DNA (eDNA) to biofilm matrix and overall structure. This work examined the presence and quantified the amount of eDNA in C. albicans biofilm ECM and the effect of DNase treatment and the addition of exogenous DNA on C. albicans biofilm development as indicators of a role for eDNA in biofilm development. We were able to detect the accumulation of eDNA in biofilm ECM extracted from C. albicans biofilms formed under conditions of flow, although the quantity of eDNA detected differed according to growth conditions, in particular with regards to the medium used to grow the biofilms. Experiments with C. albicans biofilms formed statically using a microtiter plate model indicated that the addition of exogenous DNA (>160 ng/ml) increases biofilm biomass and, conversely, DNase treatment (>0.03 mg/ml) decreases biofilm biomass at later time points of biofilm development. We present evidence for the role of eDNA in C. albicans biofilm structure and formation, consistent with eDNA being a key element of the ECM in mature C. albicans biofilms and playing a predominant role in biofilm structural integrity and maintenance.

A proteomic-based approach for the identification of immunodominant Cryptococcus neoformans proteins.

Cryptococcus neoformans is an opportunistic fungal pathogen that can cause life-threatening meningoencephalitis in immune compromised patients. Previous, studies in our laboratory have shown that prior exposure to an IFN-gamma-producing C. neoformans strain (H99gamma) elicits protective immunity against a second pulmonary C. neoformans challenge. Here, we characterized the antibody response produced in mice protected against experimental pulmonary C. neoformans infection compared to nonprotected mice. Moreover, we evaluated the efficacy of using serum antibody from protected mice to detect immunodominant C. neoformans proteins. Protected mice were shown to produce significantly more C. neoformans-specific antibodies following a second experimental pulmonary cryptococcal challenge compared to nonprotected mice. Immunoblot analysis of C. neoformans proteins resolved by 2-DE using serum from nonprotected mice failed to show any reactivity. In contrast, serum from protected mice was reactive with several cryptococcal protein spots. Analysis of these spots by capillary HPLC-ESI-MS/MS identified several cryptococcal proteins shown to be associated with the pathogenesis of cryptococcosis. Our studies demonstrate that mice immunized with C. neoformans strain H99gamma produce antibodies that are immune reactive against specific cryptococcal proteins that may provide a basis for the development of immune based therapies that induce protective anticryptococcal immune responses.

Characteristics of Candida albicans biofilms grown in a synthetic urine medium.

Urinary tract infections (UTIs) are the most common type of nosocomial infection, and Candida albicans is the most frequent organism causing fungal UTIs. Presence of an indwelling urinary catheter represents a significant risk factor for UTIs. Furthermore, these infections are frequently associated with the formation of biofilms on the surface of these catheters. Here, we describe the characterization of C. albicans biofilms formed in vitro using synthetic urine (SU) medium and the frequently used RPMI medium and compare the results. Biofilms of C. albicans strain SC5314 were formed in 96-well microtiter plates and on silicon elastomer pieces using both SU and RPMI media. Biofilm formation was monitored by microscopy and a colorimetric XTT [2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction assay. As in biofilms grown in RPMI medium, time course studies revealed that biofilm formation using SU medium occurred after an initial adherence phase, followed by growth, proliferation, and maturation. However, microscopy techniques revealed that the architectural complexity of biofilms formed in SU medium was lower than that observed for those formed using RPMI medium. In particular, the level of filamentation of cells within the biofilms formed in SU medium was diminished compared to those in the biofilms grown in RPMI medium. This observation was also corroborated by expression profiling of five filamentation-associated genes using quantitative real-time reverse transcriptase PCR. Sessile C. albicans cells were resistant to fluconazole and amphotericin B, irrespective of the medium used to form the biofilms. However, caspofungin exhibited potent in vitro activity at therapeutic levels against C. albicans biofilms grown in both SU and RPMI media.

Effect of tunicamycin on Candida albicans biofilm formation and maintenance.

BACKGROUND: Candida albicans is a common opportunistic pathogen of the human body and is the frequent causative agent of candidiasis. Typically, these infections are associated with the formation of biofilms on both host tissues and implanted biomaterials. As a result of the intrinsic resistance of C. albicans biofilms to most antifungal agents, new strategies are needed to combat these infections. METHODS: Here we have used a 96-well microtitre plate model of C. albicans biofilm formation to study the inhibitory effect of tunicamycin, a nucleoside antibiotic that inhibits N-linked glycosylation affecting cell wall and secreted proteins, on C. albicans biofilm formation. A proteomic approach was used to study the effect of tunicamycin on levels of glycosylation of key secreted mannoproteins in the biofilm matrix. RESULTS: Our results revealed that physiological concentrations of tunicamycin displayed significant inhibitory effects on biofilm development and maintenance, while not affecting overall cell growth or morphology. However, tunicamycin exerted a minimal effect on fully mature, pre-formed C. albicans biofilms. CONCLUSIONS: The effect of tunicamycin on the C. albicans biofilm mode of growth demonstrates the importance of N-linked glycosylation in the developmental stages of biofilm formation. In addition, our results indicate that N-linked glycosylation represents an attractive target for the development of alternative strategies for the prevention of biofilm formation by this important pathogenic fungus.

Prognostic Effect of Carcinoma In Situ in Muscle-invasive Urothelial Carcinoma Patients Receiving Neoadjuvant Chemotherapy.

BACKGROUND: Carcinoma in situ (CIS) is a poor prognostic finding in urothelial carcinoma. However, its significance in muscle-invasive urothelial carcinoma (MIUC) treated with neoadjuvant chemotherapy (NAC) is uncertain. We assessed the effect of CIS found in pretreatment transurethral resection of bladder tumor (TURBT) biopsies on the pathologic and clinical outcomes. MATERIALS AND METHODS: Subjects with MIUC treated with NAC before cystectomy were identified. The pathologic complete response (pCR) rates stratified by TURBT CIS status were compared. The secondary analyses included tumor response, progression-free survival (PFS), overall survival (OS), and an exploratory post hoc analysis of patients with pathologic CIS only (pTisN0) at cystectomy. RESULTS: A total of 137 patients with MIUC were identified. TURBT CIS was noted in 30.7% of the patients. The absence of TURBT CIS was associated with a significantly increased pCR rate (23.2% vs. 9.5%; odds ratio, 4.08; 95% confidence interval, 1.19-13.98; P = .025). Stage pTisN0 disease was observed in 19.0% of the TURBT CIS patients. TURBT CIS status did not significantly affect the PFS or OS outcomes. Post hoc analysis of the pTisN0 patients revealed prolonged median PFS (104.5 vs. 139.9 months; P = .055) and OS (104.5 vs. 152.3 months; P = .091) outcomes similar to those for the pCR patients. CONCLUSION: The absence of CIS on pretreatment TURBT in patients with MIUC undergoing NAC was associated with increased pCR rates, with no observed differences in PFS or OS. Isolated CIS at cystectomy was frequently observed, with lengthy PFS and OS durations similar to those for pCR patients. Further studies aimed at understanding the biology and clinical effect of CIS in MIUC are warranted.

A role for Efg1p in Candida albicans interactions with extracellular matrices.

Candida albicans interactions with extracellular matrices extracellular matrices represent hallmarks of invasive candidiasis. We have assessed the role of Efg1p, a key transcriptional regulator, in the interactions between C. albicans and extracellular matrices. Wild-type C. albicans cells were able to bind and subsequently penetrate the extracellular matrices layer, whereas the Deltaefg1/Deltaefg1 mutant strain showed a drastically reduced ability to interact with extracellular matrices. Results indicate that, besides its control of morphogenesis, Efg1p also regulates C. albicans interactions with extracellular matrices. Proteomic analyses indicated that expression of 30 surface-associated proteins is affected in the Deltaefg1/Deltaefg1 mutant, some of which may be involved in adherence to extracellular matrices.