Adhesion of Candida albicans to Endothelial Cells under Physiological Conditions of Flow

Candida albicans is a commensal organism that under certain circumstances can become pathogenic. During systemic infection C. albicans is disseminated via the circulation to distant organs, where it causes multiple organ failure. Despite the severity of systemic C. albicans infection, little is known about the mechanisms involved in the adhesion of this organism to the endothelium lining blood vessels. Previous studies have used static assays to examine adhesion. However, these do not realistically model blood vessels, where circulating C. albicans cells must adhere to the endothelium under conditions of flow and shear stress. Furthermore, there is conflicting evidence concerning the role played by yeast, pseudohyphal, and hyphal forms of C. albicans in adhesion to endothelium. To test the hypothesis that there may be differences in the abilities of these three morphogenic forms of C. albicans to adhere to endothelium under conditions of flow, we developed an in vitro flow adhesion assay. We found that all three forms of C. albicans rapidly bound to confluent endothelial cells under conditions of flow. Maximum adhesion was found at low shear stress levels similar to that found in postcapillary venules. Moreover, yeast forms bound in significantly greater numbers than did pseudohyphal and hyphal forms, respectively, contrasting with previous findings from static assays. These findings are consistent with recent in vivo data suggesting that yeast forms may be capable of adhering to the endothelium and migrating into the tissues before undergoing morphogenic change to cause tissue damage.Candida albicans is a normal commensal organism of the oral cavity, gastrointestinal tract, and vagina. Usually the organism colonizes these mucosal surfaces without causing infection. However, under certain circumstances it is capable of becoming pathogenic. Systemic candidiasis is a serious infection with a high mortality rate and morbidity in those who survive (26). After infections caused by methicillin (meticillin)-resistant Staphylococcus aureus, it is probably the second most common cause of death from hospital-acquired infections and involves the hematogenous spread of C. albicans to multiple organs (11, 27). Mucocutaneous candidal infections seldom lead to systemic candidiasis. Even fungal colonization of the lungs and gastrointestinal tract does not always lead to systemic infection but may occur when surface integrity and host defenses are impaired. Systemic candidiasis appears to occur most often when direct access of fungi is facilitated by major gastrointestinal or cardiac surgery, organ transplantation, or the use of indwelling intravascular catheters and devices (13).During systemic dissemination, circulating C. albicans must first adhere to the endothelial cells lining blood vessels before transmigrating across the vessel wall and entering the tissues. Despite the morbidity caused by systemic candidiasis, little is known about the mechanisms involved in the adhesion of C. albicans to endothelial cells or their subsequent transmigration. Currently, there are two different theories as to how C. albicans adheres to the endothelium and enters the tissues (reviewed in reference 10). The first theory proposes that C. albicans must undergo morphogenic conversion from yeast to hyphal forms within the circulation to be able to invade the tissues (6, 19, 21). However, more-recent data indicate that morphogenic change may not be necessary, suggesting that yeast cells may be able to adhere to the endothelium and transmigrate into the tissues before undergoing morphogenic change (3, 4, 23, 24).Studies investigating candidal adhesion to the endothelium have mainly used static in vitro assays where C. albicans is left in prolonged contact with cultured monolayers of endothelial cells. This is very different from the fleeting interactions that C. albicans has with endothelial cells under conditions of shear stress and flow that occur in blood vessels in vivo. Numerous studies with leukocytes, tumor cells, and microorganisms have shown that static assays do not replicate the dynamic interactions that occur with endothelium under conditions of flow and are poor at elucidating the contribution of specific adhesion molecules (8, 14). However, to date no studies have investigated the adhesion of the three different morphogenic forms of C. albicans to endothelium under conditions of flow.To test the hypothesis that there may be differences in the abilities of yeast, pseudohyphal, and hyphal forms of C. albicans to adhere to the endothelium under conditions of flow, we developed an in vitro flow adhesion assay that mimics the conditions found within blood vessels. Here we show for the first time that adhesion of all three forms of C. albicans to the endothelium under conditions of flow is rapid. In addition, yeast forms adhere with greater numbers than do pseudohyphal or hyphal forms, suggesting that yeast forms may be the most predominant form adhering to endothelial cells during systemic infection.     

Using nestling feathers to assess spatial and temporal concentrations of mercury in bald eagles at Voyageurs National Park, Minnesota, USA

Bald eagles (Haliaeetus leucocephalus) have been utilized as a biosentinel of aquatic ecosystem health in the Great Lakes Region since the early 1960s. Bald eagle populations have been monitored at Voyageurs National Park (VNP), Minnesota, since 1973. For the past 20 years, researchers have collected feathers from nestling bald eagles to assess their dietary exposure to mercury (Hg) on Rainy, Kabetogama, and Namakan lakes in VNP. Mercury is an environmental pollutant with both natural and anthropogenic sources, and negatively affects many species of wildlife. In a previous study, geometric mean concentrations of Hg in feathers of nestling bald eagles were greater at VNP (20 mg/kg Dry Weight (DW)) than in nestling feathers from other Great Lakes subpopulations (~7 mg/kg DW), for the period 1985–1989. Current geometric mean concentrations have declined by 77.4% since 1989 at VNP. While all samples from 1985 to 1989 had detectable concentrations of Hg, 10% of current samples had concentrations below the reportable detection limit (0.001 mg/kg DW, n = 180). The major lakes at VNP are impounded, and Hg concentrations also declined greatly after the lake level stabilization order by the International Joint Commission was implemented in 1999. Mercury concentrations in feathers of nestling bald eagles from 1989 to 2010 ranged from ND (<0.001) to 34.97 mg/kg DW. The highest single concentration in a nestling was from Namakan Lake in 2010. The five-year geometric means for Rainy, Kabetogama, and Namakan lakes for 2006–2010 were 6.08, 1.07, and 5.56 mg/kg DW (n = 28, n = 32, n = 27) respectively. Although Hg concentrations in feathers of nestlings greatly declined after the change in water level management in 1999 and are lower than 1989 concentrations, recent samples suggest a gradual increase. Continued monitoring of nestling feather concentrations will be essential to assess this increase, to determine the source of Hg, to determine if there are changes to methylation potential, and to evaluate and optimize water level management.     

Ovarian activity and safety of a novel levonorgestrel/ethinyl estradiol continuous oral contraceptive regimen

Background

A continuous regimen of oral levonorgestrel (LNG) 90 mcg/ethinyl estradiol (EE) 20 mcg was evaluated for inhibition of ovulation, time to return to ovulation after stopping treatment and safety.

Study Design

This open-label study was conducted in healthy women aged 18-35 years. Ovulation was documented before treatment, and then participants received oral tablets containing LNG 90 mcg/EE 20 mcg to be taken continuously for three 28-day intervals. Ovarian activity was assessed three times per week during the treatment period with transvaginal ultrasound scans and measurements of serum 17β-estradiol, progesterone, follicle-stimulating hormone and luteinizing hormone concentrations. Safety assessments included physical examinations, laboratory evaluations and adverse event records.

Results

Thirty-seven of the 58 subjects who received treatment met predefined criteria for efficacy analysis. No on-treatment ovulations occurred in the efficacy or intent-to-treat population. There was evidence of ovulation within 37 days of stopping treatment for 46 (98%) of 47 subjects evaluated posttreatment. The final subject with a history of polycystic ovarian syndrome ovulated by Day 66. The safety profile observed during this 84-day continuous regimen was similar to that seen with other low-dose oral contraceptives administered in a cyclic regimen.

Conclusions

The continuous LNG/EE regimen completely inhibited ovulation, with little evidence of follicular development and with rapid return of ovulatory capacity after stopping treatment.     

New-onset orthostatic intolerance following bariatric surgery

Background: As bariatric surgery has become an increasingly popular treatment for obesity, we have seen an increasing number of patients present after bariatric surgery with new-onset syncope, near-syncope, and lightheadedness.
Methods: We retrospectively reviewed patients who had had bariatric surgery referred to our institution for evaluation of orthostatic intolerance. We reviewed history, physical examination, type of bariatric surgery procedure, and tilt table test results in these patients. There were 14 women and one man with mean age 42 ± 6 years, preoperative body mass index was 49.3 ± 6.0 kg/m², and mean postoperative weight loss was 55.9 kg. Mean onset of symptoms was 5.2 ± 3.9 months after surgery. Presenting symptoms were lightheadedness in 15 (100%), near-syncope in 11 (73%), and syncope in nine (60%). All but one patient had a positive tilt table test with eight (53%) having a neurocardiogenic response, three (20%) having a dysautonomic response, and (20%) having a postural tachycardia response. The likely mechanism of orthostatic intolerance is autonomic insufficiency in combination with reverse course of obesity-related hypertension. The majority of the patients (12 out of 15) responded to standard therapy for autonomic insufficiency.
Conclusion: Some patients may develop significant orthostatic intolerance due to autonomic insufficiency following bariatric surgery, and awareness of the potential association between bariatric surgery and new orthostatic intolerance is important for providing timely care.     

Hereditary leiomyomatosis and renal cell cancer: a syndrome associated with an aggressive form of inherited renal cancer

PURPOSE: Hereditary leiomyomatosis and renal cell cancer is a recently described hereditary cancer syndrome in which affected individuals are at risk for cutaneous and uterine leiomyomas, and kidney cancer. Our initial experience revealed the aggressive behavior of these renal tumors, often with early metastasis, despite small primary tumor size. We report the clinical characteristics and urological treatment of patients with hereditary leiomyomatosis and renal cell cancer associated renal tumors. MATERIALS AND METHODS: A total of 19 patients with hereditary leiomyomatosis and renal cell cancer associated renal tumors were evaluated. The 11 women and 8 men had a median age at diagnosis of 39 years (range 22 to 67), and a median clinical and radiological followup of 34 months (range 6 to 141). Hereditary leiomyomatosis and renal cell cancer manifestations in patients with renal tumors included cutaneous leiomyomas in 11 of 17 evaluable patients (65%) and uterine leiomyomas in 7 of 7 evaluable females (100%). RESULTS: Median pathological tumor size was 7.8 cm (range 1.5 to 20). Histological subtypes were consistent with hereditary leiomyomatosis and renal cell cancer renal carcinoma. Four of 7 patients with 2.0 to 6.7 cm T1 tumors had spread to regional lymph nodes or metastases at nephrectomy. Overall 9 of 19 patients (47%) presented with nodal or distant metastases. CONCLUSIONS: Renal tumors in patients with hereditary leiomyomatosis and renal cell cancer syndrome are significantly more aggressive than those in patients with other hereditary renal tumor syndromes. In contrast to other familial renal cancer syndromes, the observation of 3 cm or less renal tumors associated with hereditary leiomyomatosis and renal cell cancer is not recommended. Careful followup of affected and at risk individuals in families is necessary.     

A novel magnetic approach to enhance the efficacy of cell-based gene therapies

Attempts have been made to use various forms of cellular vectors to deliver therapeutic genes to diseased tissues like malignant tumours. However, this approach has proved problematic due to the poor uptake of these vectors by the target tissue. We have devised a novel way of using magnetic nanoparticles (MNPs) to enhance the uptake of such 'therapeutically armed' cells by tumours. Monocytes naturally migrate from the bloodstream into tumours, so attempts have been made to use them to deliver therapeutic genes to these sites. However, transfected monocytes injected systemically fail to infiltrate tumours in large numbers. Using a new in vitro assay for assessing monocyte extravasation, we show that the ability of transfected human monocytes to migrate across a human endothelial cell layer into a 3D tumour spheroid is markedly increased when cells are pre-loaded with MNPs and a magnetic force is applied close to the spheroid. Furthermore, systemic administration of such 'magnetic' monocytes to mice bearing solid tumours led to a marked increase in their extravasation into the tumour in the presence of an external magnet. This new magnetic targeting approach could be used to increase the targeting, and thus the efficacy, of many cell-based gene therapies in vivo.     

What do psychiatric emergency patients really want and how do they feel about what they get?

Psychiatric emergency patients range along a continuum from persons who present to the service with specific requests for help, to individuals who are brought to the service in handcuffs against their will for reasons they do not understand. In addition, studies suggest that psychiatric emergency patients' wishes and expectations often fall outside the traditional framework of psychiatric assessment (1), are not straightforward or concrete (2) or are not accurately perceived by the clinicians who see them (3). How these factors impact on patient satisfaction with the treatment they have received is not well-understood, because the manner in which specific patient variables and treatments might relate to patient satisfaction among the psychiatric emergency service population has not been systematically studied (4) (5) (6). In contrast, psychiatric inpatients and outpatients (7) (8) (9) usually express positive attitudes about their mental health care, although this finding may be skewed by a lack of real anonymity (10). Chronic patients tend to express less satisfaction with their treatment programs than do others, and patient satisfaction in some studies has been related to patient demographics, diagnoses, treatment histories (11) and patients' global rating of treatment outcome (12).