Hydrophobic surface protein masking by the opportunistic fungal pathogen Candida albicans.

Ultrastructural and biochemical analyses of hydrophobic and hydrophilic yeast cell surface proteins of Candida albicans were performed. Hydrophobic and hydrophilic yeast cells were obtained by growth at 23 and 37 degrees C, respectively. In addition, hydrophilic yeast cells were converted to surface hydrophobicity by treatment with tunicamycin and dithiothreitol. When freeze-etched cells were examined, the temperature-induced hydrophilic cells had long (0.198 micron), compact, evenly distributed fibrils while temperature-induced hydrophobic cells had short (0.085 micron), blunt fibrils. Hydrophobic microsphere attachment to the hydrophobic cells occurred at the basement of and within the short fibril layer. Dithiothreitol-induced hydrophobic cells had the long fibrils removed; tunicamycin-induced hydrophobic cells retained some of the long fibrils, but the fibrils were less compact and more aggregated than the untreated controls. These results suggest that the long fibrils prevent hydrophobic microsphere attachment to the hydrophobic area of the cell surface. This was confirmed by assessing the hydrophobic avidity of hydrophobic yeast cell populations differing in fibril density and arrangement. 125I-labelled surface proteins from hydrophobic and hydrophilic cells were compared after separation by hydrophobic interaction chromatography-high-performance liquid chromatography and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. The yeast cell populations had hydrophilic proteins of similar molecular masses (greater than 200 kDa), but the hydrophilic cells possessed at least two additional proteins (ca. 63 and 69 to 71 kDa). Hydrophobic surface proteins appeared to be similar. However, the amount of total radiolabelled hydrophobic proteins was approximately 10-fold higher for the hydrophobic cells than for the hydrophilic cells. This result agrees with the ultrastructural observations which showed that yeast cell surface hydrophobic proteins are masked by hydrophilic high-molecular-mass surface fibrils. Taken together, the data indicate that yeast cell hydrophobicity is not determined by differences in surface hydrophobic proteins but by the presence of hydrophilic, surface fibrils.     

Role of yeast cell growth temperature on Candida albicans virulence in mice.

Previous studies have suggested that yeast cell growth temperature may influence the relative virulence of the opportunistic dimorphic fungus Candida albicans. To test this possibility, mice were challenged with C. albicans yeast cells which were grown at either room temperature or 37 degrees C, and their survival was monitored daily. Mice which received room temperature-grown cells died faster. The interaction of glycogen-elicited polymorphonucleated neutrophils (PMNs) with C. albicans yeast cells grown at the two temperatures was examined, because PMNs have been shown to have a critical role in preventing development of candidiasis in normal individuals. In the absence of serum (i.e., nonopsonic conditions), more PMNs conjugated and engulfed C. albicans cells grown at room temperature than those grown at 37 degrees C. However, PMNs were less able to kill cells grown at room temperature than cells grown at 37 degrees C. Cells grown at room temperature also produced abundant germ tubes after engulfment and were thus more likely to escape killing by phagocytes. These results suggest that cells grown at room temperature are more virulent because they are less likely to be killed by phagocytes and are more likely to disseminate. The possibility that expression of cell surface hydrophobicity is involved in these events is discussed.     

Dynamic expression of cell surface hydrophobicity during initial yeast cell growth and before germ tube formation of Candida albicans.

Expression of cell surface hydrophobicity (CSH) during initial growth of Candida albicans was monitored. CSH of hydrophobic and hydrophilic yeast cells changed within 30 min upon subculture into fresh medium. Morphologic evidence of germination was preceded by expression of CSH. These results indicate that CSH expression is important in C. albicans growth.     

Expression of surface hydrophobic proteins by Candida albicans in vivo.

Candida albicans modulates cell surface hydrophobicity during growth and morphogenesis in vitro. To determine if surface hydrophobicity is expressed during pathogenesis, we generated a polyclonal antiserum against yeast hydrophobic proteins. The antiserum was then used for indirect immunofluorescence analysis of tissues from mice colonized and chronically infected with C. albicans. Results demonstrated that yeast hydrophobic proteins are exposed on fungal cells present in host tissues. The polyclonal antiserum distinguished between hydrophobic and hydrophilic cell surfaces in vitro and gave similar staining patterns and intensities for C. albicans cells in vivo. Of the yeast forms present within tissue lesions, approximately half exhibited moderate to intense immunofluorescence with the antiserum. Immunoblot analysis indicated that antigens recognized by the antiserum are predominantly low-molecular-mass hydrophobic proteins that are expressed by different C. albicans isolates and are expressed regardless of growth temperature. Taken together, the immunofluorescence and immunoblot analyses of antigens indicate that C. albicans displays surface hydrophobic proteins during pathogenesis and these proteins are available for hydrophobic interactions with host tissues. The effect of hydrophobic protein exposure on the virulence of C. albicans is discussed.     

Battle fatigue identification and management for military medical students.

Battle fatigue, a temporary response to the stress of combat capable of reducing the fighting force by 10% to 50%, is an inevitable consequence of military conflict. Effective application of established preventive and management techniques by line and medical corps personnel can turn this "force reducer" into a "force multiplier," returning 80% or more of these seasoned troops to their original units within 72 hours. The proper management of battle fatigue is an essential readiness element in the medical support mission. The "Battle Fatigue Identification and Management" course prepares future military medical officers for this important contingency role.     

Pathways to earned-security: The role of alternative support figures

This study explored the kinds of relationship experiences associated with earned-security, i.e., the extent to which mothers who report early negative relationship histories with their parents are later able to form a secure working model of attachment (indicated by the ability to speak clearly and coherently about these histories). Mothers from a low-risk sample (N = 121) expecting their first child completed the Adult Attachment Interview (AAI), which was used to assess earned-security retrospectively using the stringent definition recommended by Main and Hesse (Hesse, 2008 Hesse, E. 2008. “The Adult Attachment Interview: Protocol, method of analysis, and empirical studies”. In The handbook of attachment: Theory, research and clinical applications, Edited by: Cassidy, J. and Shaver, P. R. 552–598. New York, NY: The Guilford Press.  [Google Scholar]; Main, Goldwyn, & Hesse, 2002 Main, M., Goldwyn, R. and Hesse, E. 2002/2008. Adult attachment scoring and classification system, Unpublished scoring manual, University of California at Berkeley.  [Google Scholar]), as well as to identify alternative support figures. Participants also completed self-report measures of depressive symptomatology, questionnaires concerning their experiences in therapy, and later, when their babies were 12 to 15 months old, the Strange Situation procedure. Sixteen mothers were classified as earned-secure (25% of those classified as secure-autonomous and 13% of the whole sample). Women who were earned-secure (vs. insecure and continuous-secure) reported significantly higher levels of emotional support, but not instrumental support, from alternative support figures. They also spent more time in therapy than did insecure and continuous-secure women and were more likely to form secure attachments with their infants than insecure women. These findings were obtained even after controlling for depressive symptoms.     

Mutations of the hemophagocytic lymphohistiocytosis-associated gene UNC13D in a patient with systemic juvenile idiopathic arthritis

The clinical syndromes of hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are both characterized by dysregulated inflammation with prolonged fever, hepatosplenomegaly, coagulopathy, hematologic cytopenias, and evidence of hemophagocytosis in the bone marrow or liver. While HLH is either inherited or acquired, children with severe rheumatic diseases, most notably systemic juvenile idiopathic arthritis, are at risk for MAS. The phenotypic similarity between HLH and MAS raises the possibility that they share common pathogenetic mechanisms. Familial forms of HLH have been attributed to mutations in the genes encoding perforin (PRF1) and Munc13-4 (UNC13D), among others, and are characterized by defective cytotoxic lymphocyte function. While some patients with systemic JIA have decreased levels of perforin protein expression and natural killer (NK) cell function, mutations of HLH-associated genes in patients with systemic JIA have not been reported. We report the case of an 8-year-old girl with systemic JIA without MAS who was found to have compound heterozygous mutations of UNC13D and reduced NK cell cytotoxic function. This case broadens the range of clinical phenotypes attributable to UNC13D mutations and offers new insights into the etiology and pathogenesis of systemic JIA.     

Plasma Ceruloplasmin,a Regulator of Nitric Oxide Activity,and Incident Cardiovascular Risk in Patients with CKD

Background and objectives

Increased serum levels of the acute-phase reactant ceruloplasmin predict adverse clinical outcomes in the setting of acute coronary syndromes and heart failure, but their role in patients with CKD is unclear. This study investigated the relationship of ceruloplasmin with clinical outcomes in CKD, especially with regard to traditional cardiac biomarkers.

Design, setting, participants, & measurements

Serum ceruloplasmin levels in consecutive study participants with CKD (n=654; estimated GFR<60 ml/min per 1.73 m²) as well as a control group of non-CKD participants matched for age and sex (n=250) were measured. Study participants were enrolled during 2001–2006 from a population of patients presenting for elective diagnostic coronary angiography and prospectively followed for 3 years (median follow-up=1095 days) to determine incident major adverse cardiac events (defined as a composite of death, nonfatal myocardial infarction, and stroke).

Results

Serum ceruloplasmin levels in CKD patients were elevated versus controls (median [interquartile range]; 25.5 [21.8–29.6] versus 22.7 [19.7–26.5] mg/dl; P<0.001) and associated with increased risk of future major adverse cardiac events (hazard ratio, 1.35; 95% confidence interval, 1.0 to 1.82; P=0.04). After adjusting for traditional risk factors, higher serum ceruloplasmin was still associated with higher risk of major adverse cardiac events at 3 years (hazard ratio, 1.61; 95% confidence interval, 1.15 to 2.25; P=0.01).

Conclusion

In CKD patients, increased serum ceruloplasmin, a regulator of nitric oxide activity, is associated with increased risk of long-term adverse cardiovascular events, even after multivariable model adjustment for traditional clinical and biologic risk factors.