The pathogenic yeast Cryptococcus neoformans produces a laccase enzyme (CNLAC1), which catalyzes the synthesis of melanin in the presence of phenolic compounds. A number of genes have been implicated in the regulation of laccase and melanization, including IPC1, GPA1, MET3, and STE12. Albino mutants derived from random mutagenesis techniques may contain mutations in genes that regulate multiple virulence factors, including CNLAC1. The goal of our study is to investigate the role of CNLAC1 in virulence and evasion of pulmonary host defenses after infection via the respiratory tract. Using a set of congenic laccase-positive (2E-TUC-4) and laccase-deficient (2E-TU-4) strains, we found that both strains are avirulent at a lower dose (10 4 CFU/mouse) in mice. After the infectious dose was increased to 10 6 CFU/mouse, 70% mortality was observed in mice infected with 2E-TUC-4 compared to no mortality in mice infected with 2E-TU-4 at day 30 postinfection. This observation confirms the requirement for CNLAC1 in virulence. Interestingly, we observed no differences between the two strains in pulmonary growth or in elicitation of cellular immune responses in the lung. The only measurable defect of 2E-TU-4 was in dissemination to extrapulmonary sites. To examine the role of CNLAC1 in dissemination, mice were infected intravenously. By week 3 postinfection, equal numbers of strains 2E-TUC-4 and 2E-TU-4 were recovered from the brain and spleen. This observation indicates that CNLAC1 facilitates escape from the lung, but not growth in the lungs or brain, and suggests a novel role for CNLAC1 in virulence during an infection aquired via the respiratory tract.Cryptococcus neoformans is an opportunistic pathogenic yeast acquired via the respiratory tract. Clearance of a pulmonary infection requires the development of adaptive immunity. In immunocompromised hosts, C. neoformans can disseminate to extra-pulmonary sites, particularly the central nervous system (CNS), where infection can lead to fatal meningitis. C. neoformans produces a number of factors that are required for virulence, including growth at 37°C (13), the presence of polysaccharide capsule (5), urease (9), phospholipase B (7), and laccase (31,33,39).C. neoformans produces a phenoloxidase, or laccase (encoded by the CNLAC1 gene), that catalyzes melanin production from an exogenous diphenolic or indolic substrate (catecholamine, epinephrine, L-dopa, dopamine, and caffeic acid) (26). The resulting heterogeneous pigment is covalently linked to the cell wall (42). In addition to melanin, a variety of potentially toxic by-products are produced by laccase. Both melanin and laccase by-products have been detected in vivo (19,23). Therefore, multiple products of the laccase pathway likely play a role in virulence.In vitro studies have identified a number of possible molecular mechanisms for the role of laccase during pathogenesis. Melanin provides increased resistance to antifungal drugs (37), antibody-mediated phagocytosis (36), and defensins (10), and it is an antioxidant both...

Utilizing an optimized, noncontrast 1.5-T MRI protocol, we report the previously undescribed prevalence of acetabular labral pathological abnormalities and paralabral cysts in a young, asymptomatic population. This emphasizes the importance of correlating patient symptoms with history and physical examination when evaluating patients with hip pain and radiographic abnormalities as defined by MRI criteria. These data demonstrate that labral tears can occur without symptoms.

The objective of this study was to induce anterior cruciate ligament (ACL) and meniscal damage, via a single tibiofemoral compressive impact, in order to document articular cartilage and meniscal changes post impact. Tibiofemoral joints of Flemish Giant rabbits were subjected to a single blunt impact that ruptured the ACL and produced acute meniscal damage. Animals were allowed unrestricted cage activity for 12 weeks before euthanasia. India ink analysis of the articular cartilage revealed higher degrees of surface damage on the impacted tibias (p=0.018) and femurs (p<0.0001) compared to controls. Chronic meniscal damage was most prevalent in the medial central and medial posterior regions. Mechanical tests revealed an overall 19.4% increase in tibial plateau cartilage thickness (p=0.026), 34.8% increase in tibial plateau permeability (p=0.054), 40.8% increase in femoral condyle permeability (p=0.029), and 20.1% decrease in femoral condyle matrix modulus (p=0.012) in impacted joints compared to controls. Both the instantaneous and equilibrium moduli of the lateral and medial menisci were decreased compared to control (p<0.02). Histological analyses revealed significantly increased presence of fissures in the medial femur (p = 0.036). In both the meniscus and cartilage there was a significant decrease in GAG coverage for the impacted limbs. Based on these results it is clear that an unattended combined meniscal and ACL injury results in significant changes to the soft tissues in this experimental joint 12 weeks post injury. Such changes are consistent with a clinical description of mid to late stage PTOA of the knee.

Subchondral bone is thought to play a significant role in the initiation and progression of the post-traumatic osteoarthritis. The goal of this study was to document changes in tibial and femoral subchondral bone that occur as a result of two lapine models of anterior cruciate ligament injury, a modified ACL transection model and a closed-joint traumatic compressive impact model. Twelve weeks post-injury bones were scanned via micro-computed tomography. The subchondral bone of injured limbs from both models showed decreases in bone volume and bone mineral density. Surgical transection animals showed significant bone changes primarily in the medial hemijoint of femurs and tibias, while significant changes were noted in both the medial and lateral hemijoints of both bones for traumatic impact animals. It is believed that subchondral bone changes in the medial hemijoint were likely caused by compromised soft tissue structures seen in both models. Subchondral bone changes in the lateral hemijoint of traumatic impact animals are thought to be due to transmission of the compressive impact force through the joint. The joint-wide bone changes shown in the traumatic impact model were similar to clinical findings from studies investigating the progression of osteoarthritis in humans.

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