Activation of EphA2-EGFR signaling in oral epithelial cells by Candida albicans virulence factors

During oropharyngeal candidiasis (OPC), Candida albicans invades and damages oral epithelial cells, which respond by producing proinflammatory mediators that recruit phagocytes to foci of infection. The ephrin type-A receptor 2 (EphA2) detects β-glucan and plays a central role in stimulating epithelial cells to release proinflammatory mediators during OPC. The epidermal growth factor receptor (EGFR) also interacts with C. albicans and is known to be activated by the Als3 adhesin/invasin and the candidalysin pore-forming toxin. Here, we investigated the interactions among EphA2, EGFR, Als3 and candidalysin during OPC. We found that EGFR and EphA2 constitutively associate with each other as part of a heteromeric physical complex and are mutually dependent for C. albicans-induced activation. Als3-mediated endocytosis of a C. albicans hypha leads to the formation of an endocytic vacuole where candidalysin accumulates at high concentration. Thus, Als3 potentiates targeting of candidalysin, and both Als3 and candidalysin are required for C. albicans to cause maximal damage to oral epithelial cells, sustain activation of EphA2 and EGFR, and stimulate pro-inflammatory cytokine and chemokine secretion. In the mouse model of OPC, C. albicans-induced production of CXCL1/KC and CCL20 is dependent on the presence of candidalysin and EGFR, but independent of Als3. The production of IL-1α and IL-17A also requires candidalysin but is independent of Als3 and EGFR. The production of TNFα requires Als1, Als3, and candidalysin. Collectively, these results delineate the complex interplay among host cell receptors EphA2 and EGFR and C. albicans virulence factors Als1, Als3 and candidalysin during the induction of OPC and the resulting oral inflammatory response.

Oropharyngeal candidiasis occurs when the fungus Candida albicans proliferates in the mouth to a point at which tissue damage occurs. The disease is characterized by fungal invasion of the superficial epithelium and a localized inflammatory response. Two C. albicans virulence factors contribute to the pathogenesis of OPC, Als3 which enables the organism to adhere to and invade host cells, and candidalysin which is a pore-forming toxin that damages host cells. Two epithelial cell receptors, ephrin type-A receptor 2 (EphA2) and the epidermal growth factor receptor (EGFR) are activated by C. albicans. Here, we show that EphA2 and EGFR form part of complex wherein these co-receptors are required to activate each other. Als3 enhances the host cell targeting of candidalysin by stimulating epithelial cell endocytosis of C. albicans, leading to the formation of an endocytic vacuole in which candidalysin accumulates. Thus, Als3 and candidalysin synergize to damage epithelial cells, activate EphA2 and EGFR, and stimulate the production of inflammatory mediators. In the mouse model of OPC, candidalysin elicits of a subset of the oral inflammatory response molecular repertoire. Of the cytokines and chemokines induced by this toxin, some require the activation of EGFR while others are induced independently of EGFR. Collectively, this work provides a deeper understanding of the interactions among C. albicans virulence factors, host cell receptors and immune responses during OPC.

Complications of open anterior stabilization of the shoulder

Complications of surgery for glenohumeral instability are relatively uncommon. When they occur, salvaging failures and obtaining a stable joint can be awesome challenges. Accurate recognition of the cause of the instability and application of the appropriate surgical technique are critical. Deficiencies of the glenoid concavity, the anterior capsule, or the subscapularis may be present and require correction. Overtightening a shoulder and eliminating its normal laxity should be avoided. Loose or malpositioned hardware about the glenohumeral joint must be recognized as soon as possible and removed. The goal of treatment is to correct the deficient stabilizing mechanisms without altering normal glenohumeral function.

Useful boundaries of the subacromial bursa

The anatomic boundaries the subacromial bursa may serve as a useful guide for surgical orientation and safety. The goals of this study were to measure the minimum distance between the subdeltoid reflection of the subacromial bursa and the circumflex branch of the axillary nerve and to identify relationships between the margins of the subacromial bursa and the acromion, rotator cuff, and acromioclavicular joint. Seventeen fresh-frozen cadavers (mean age, 69 years), were included. Eleven cadavera were dissected only after the subacromial bursa was injected with a latex solution to define the peripheral boundaries of the bursa. The bursal margins were always 2 cm or more from the anterolateral corner of the bursal acromial surface and the bursa lined the anterior half of the anteroposterior distance of the acromion. The mean distances from all points of the acromion to the axillary nerve averaged approximately 5 cm. The mean minimum distance from the subdeltoid bursal reflection to the axillary nerve was 0.8 +/- 0.5 cm with a range of 0.0 to 1.4 cm. In the unelevated extremity, the inferior bursal reflection was always cephalad to the axillary nerve even when the two structures were apposed. Surgeons should exercise caution when approaching the inferior boundary of the subdeltoid bursal reflection because of the proximity to the axillary nerve. We recommend coupling previously reported "safe deltoid-split" distances to this useful anatomic landmark to prevent nerve injury. Furthermore, the central location of the anterolateral corner of the acromion within the bursal space can be applied to needle placement for injection, arthroscopic diagnosis or treatment and mini-open rotator cuff repairs.

Elbow valgus stress radiography in an uninjured population

Valgus instability of the elbow joint is a clinical diagnosis. However, many authors describe valgus stress radiographs as an aid in making this diagnosis. We studied valgus stress radiographs of 20 men (40 elbows) and 20 women (40 elbows), none with a history of elbow trauma or instability. The medial ulnohumeral distance was measured with no stress, valgus stress by gravity, and an applied valgus stress of 25 N (approximately 5 pounds). Measurements were made with the elbow positioned in extension and in 30 degrees of flexion. The increase in medial ulnohumeral gapping with either gravity or 5 pounds of stress was statistically significant at both extension and 30 degrees of flexion compared with the unstressed condition. The difference in ulnohumeral gapping between gravity stress and 5 pounds of valgus stress in extension and in 30 degrees of flexion was also significant. We found no differences with regard to hand dominance or sex. We conclude that uninjured elbows have significant medial ulnohumeral gapping on valgus stress radiography. Although this is an important tool in diagnosing valgus instability of the elbow, it may yield a false-positive assessment of valgus instability. Valgus stress radiographs comparing contralateral elbows may reduce the false-positive rate since there appears to be no significant difference in medial ulnohumeral gapping between the two elbows.

Practical guidelines to safe surgery about the subscapularis

Surgical mobilization of an adherent or retracted subscapularis tendon is often necessary whenever an attempt is made to restore function to the glenohumeral joint subsequent to failed anterior reconstructive surgery. Surgical guidelines drawn from this study emphasize how a surgeon might accomplish this task effectively and avoid denervating the subscapularis, a muscle that is essential to anterior glenohumeral stability and strength. In this study we examined subscapularis innervation in 11 fresh-frozen cadaveric shoulders. The position of the subscapular nerve insertion points were recorded relative to easily identified surgical landmarks such as the axillary nerve, the conjoined tendon, and the anterior glenoid rim. The palpable anterior border of the glenoid rim deep to the subscapularis along with the medical border of the conjoined tendon can serve as guides to the subscapularis nerve insertion points, because all the nerves are no closer than 1.5 cm medial to these landmarks for all positions of humeral rotation in the unelevated arm. The lower subscapular nerve was found immediately posterior or just lateral to the axillary nerve. During a standard deltopectoral approach potential injury to the subscapularis innervation can be minimized by locating and protecting the axillary nerve, because it serves as a guide to the insertion point of the lower subscapularis nerve, the nerve closet to the surgical field.

Effect of a chondral-labral defect on glenoid concavity and glenohumeral stability. A cadaveric model

One of the primary stabilizing mechanisms of the glenohumeral joint is concavity-compression, the maintenance of the humeral head in the concave glenoid fossa by the compressive force generated by the surrounding muscles. This mechanism is active in all glenohumeral positions but it is particularly important in the functional mid-range, in which the capsule and ligaments are slack. The effectiveness of concavity-compression in the stabilization of a joint can be characterized in terms of the ratio between the maximum dislocating force that can be stabilized in a given direction and the load compressing the head into the glenoid (the stability ratio). Glenoid concavity can be described by the lateral humeral displacement during translation across the glenoid. The purpose of the present investigation was to characterize the concavity and stability ratios of normal cadaveric glenoids, to measure the effect of an anteroinferior chondral-labral defect on these parameters, and to measure the effectiveness of a simulated operative reconstruction on the restoration of glenoid concavity and the stability ratio. The chondral-labral defect created in this study reduced the height of the glenoid by approximately 80 per cent and the stability ratio by approximately 65 per cent for translation in the direction of the defect. Reconstruction of the anteroinferior aspect of the glenoid concavity with use of an autogenous biceps-tendon graft restored normal values for these variables.

Exertional oxygen of limited benefit in patients with chronic obstructive pulmonary disease and mild hypoxemia

It is unclear whether short-term benefits from supplemental oxygen translate into improved quality of life in patients with severe COPD. In a 12 wk double-blind randomized crossover study, we assessed the effects of supplemental air and oxygen on exercise performance (step tests and 6 min walking distance [6MWD]) initially and after two 6 wk periods at home using exertional cylinder air or oxygen. We measured quality of life at baseline and after the two 6 wk domiciliary periods. The 26 patients (24 males) had a mean age of 73 +/- 6 yr; mean FEV1, 0.9 +/- 0.4 L; mean DLCO, 10.6 +/- 2.4 ml/min/mm Hg; mean resting PO2, 69 +/- 8.5 (range 58 to 82) mm Hg; mean PCO2, 41 +/- 3.3 mm Hg; and mean resting SaO2, 94 +/- 2.1 (mean +/- SD). Laboratory tests were performed breathing intranasal air or oxygen at 4 L/min, and measurements were made of SaO2 and Borg dysnea scores. Supplemental oxygen increased 6MWD and steps by small, statistically significant increments acutely at baseline and after 6 and 12 wk, without corresponding falls in Borg score. Degree of desaturation at baseline did not correlate with increase in 6MWD or steps achieved at baseline or at 6 or 12 wk, nor with the domiciliary gas used. There was no difference in 6MWD or steps achieved while breathing supplemental oxygen after 6 wk of domiciliary oxygen compared with domiciliary air. Small improvements in quality of life indices were found after domiciliary oxygen, and mastery also improved after domiciliary air. There were no differences in quality of life, however, when domiciliary oxygen was compared with domiciliary air. Although oxygen supplementation induced small acute increments in laboratory exercise performance, such improvements had little impact on the patients' daily lives.

Comparison of the inflammatory response to particulate polymethylmethacrylate debris with and without barium sulfate

Particulate polymethylmethacrylate debris has been implicated in the inflammatory response observed surrounding loosened cemented implants. The rat subcutaneous pouch model and the Howie implant model (used to study bone resorption) were used to quantify the response to mechanically produced endotoxin-free polymethylmethacrylate debris with and without 10% (wt/vol) BaSO4. In the rat subcutaneous pouch model, the inflammatory response to polymethylmethacrylate particles containing BaSO4 was greater than the response to plain polymethylmethacrylate particles of similar size. Increased inflammation was measured by leukocyte counts and levels of prostaglandin E2, tumor necrosis factor, and neutral metalloprotease. In addition, particulate polymethylmethacrylate with BaSO4 caused significantly greater bone resorption in the Howie model than did particulate plain polymethylmethacrylate. In in vitro studies, particulate polymethylmethacrylate with BaSO4 stimulated more prostaglandin E2, neutral metalloprotease, and tumor necrosis factor from human monocytes in culture and stimulated greater proliferation of synovial cells than did particulate plain polymethylmethacrylate. The presence of BaSO4 appears to significantly intensify the inflammatory response to polymethylmethacrylate debris.

Comparison of open and arthroscopic subacromial decompression

We retrospectively reviewed 68 patients (70 shoulders) who underwent either open or arthroscopic acromioplasty performed by a single surgeon (JPI) for chronic impingement syndrome in the presence of an intact rotator cuff. Group 1 consisted of 24 shoulders that had open acromioplasty and group 2 consisted of 46 shoulders that had arthroscopic acromioplasty. The minimum follow-up was 12 months for both groups. There was no statistical difference in mean postoperative shoulder scores between the operative groups. However, there were more excellent results in the open group as compared with the arthroscopic group (54.2% vs 41.9%, respectively). In addition, there was a higher percentage of poor results in group 2 as compared with group 1 (27.9% vs 16.6%, respectively). Arthroscopic acromioplasty was associated with shorter hospital stays and faster achievement of maximal pain relief as compared with open acromioplasty. Examination of postoperative radiographs often revealed subacromial calcifications. These calcifications were more frequent after arthroscopic acromioplasty and were associated with a worse result.