In vitro and in vivo toxicity of rinsed and aged nanocellulose-polypyrrole composites

Novel composites of nanocellulose and the conducting polymer polypyrrole (PPy) are herein suggested as potential candidates for active ion-extraction membranes in electrochemically controlled hemodialysis. This study has defined processing parameters to obtain a biocompatible nanocellulose-PPy composite, and for the first time, the effect of the composite aging on cell viability has been studied. The influence of rinsing and extraction process steps, as well as aging under different conditions (i.e. in air, at -20°C and in argon), on the electroactivity and cytotoxicity of a PPy-nanocellulose composite has been investigated. The biocompatibility evaluation was based on indirect toxicity assays with fibroblasts and monocyte cell lines and an acute toxicity test in mice, while the electroactivity was evaluated by cyclic voltammetry experiments. The as-prepared composite did not induce any cytotoxic response in vitro or in vivo. Extensive rinsing and 48 h incubation in biological buffer previous to the preparation of the culture medium extracts were, however, necessary to obtain a noncytotoxic composite. The as-prepared composite was also found to exhibit acceptable electrochemical performance, which was retained upon 4 weeks storage in argon atmosphere. It was shown that aging of the composite had a negative effect on biocompatibility, regardless of the storage condition. Thus, to allow for longtime storage of electroactive nanocellulose-PPy hemodialysis membranes, the degradation of PPy upon storage must be controlled. The present results show that the biocompatibility of PPy composites depends on the rinsing and pretreatment of the composite material as well as the aging of the material.     

Visuospatial ability correlates with performance in simulated gynecological laparoscopy

Objective

To analyze the relationship between visuospatial ability and simulated laparoscopy performed by consultants in obstetrics and gynecology (OBGYN).

Study design

This was a prospective cohort study carried out at two community hospitals in Sweden. Thirteen consultants in obstetrics and gynecology were included. They had previously independently performed 10-100 advanced laparoscopies. Participants were tested for visuospatial ability by the Mental Rotations Test version A (MRT-A). After a familiarization session and standardized instruction, all participants subsequently conducted three consecutive virtual tubal occlusions followed by three virtual salpingectomies. Performance in the simulator was measured by Total Time, Score and Ovarian Diathermy Damage. Linear regression was used to analyze the relationship between visuospatial ability and simulated laparoscopic performance. The learning curves in the simulator were assessed in order to interpret the relationship with the visuospatial ability.

Results

Visuospatial ability correlated with Total Time (r = −0.62; p = 0.03) and Score (r = 0.57; p = 0.05) in the medium level of the virtual tubal occlusion. In the technically more advanced virtual salpingectomy the visuospatial ability correlated with Total Time (r = −0.64; p = 0.02), Ovarian Diathermy Damage (r = −0.65; p = 0.02) and with overall Score (r = 0.64; p = 0.02).

Conclusions

Visuospatial ability appears to be related to the performance of gynecological laparoscopic procedures in a simulator. Testing visuospatial ability might be helpful when designing individual training programs.     

Randomized controlled trial of internet-based cognitive behavior therapy for distress associated with tinnitus

OBJECTIVE: The aim of this study was to investigate if cognitive behavior therapy (CBT) provided via the Internet results in significant decreases of distress in individuals with tinnitus. METHODS: Participants were recruited through Web pages and newspaper articles and thereafter randomly allocated to a CBT self-help manual in six modules or to a waiting-list control group (WLC). All treatment and contact with participants were conducted via the Internet with Web pages and E-mail correspondence. Participants were 117 individuals with tinnitus of duration of more than 6 months. In the first randomized controlled phase of the study, 26 completed all stages of treatment (51% dropout), and 64 of the WLC group completed measures. At 1-year follow-up, all participants had been offered the program and 96 provided outcome measures (18% dropout rate from baseline). Tinnitus-related problems were assessed before and after treatment and at the 1-year follow-up. Daily diary ratings were included for 1 week before and 1 week following the treatment period. RESULTS: Tinnitus-related distress, depression, and diary ratings of annoyance decreased significantly. Immediately following the randomized controlled phase (with a WLC), significantly more participants in the treatment group showed an improvement of at least 50% on the Tinnitus Reaction Questionnaire. At the uncontrolled follow-up, 27 (31%) of all participants had achieved a clinically significant improvement. CONCLUSIONS: CBT via the Internet can help individuals decrease annoyance associated with tinnitus. High dropout rates or delay in completing treatment can be a characteristic of treatment studies using the Internet but should be contrasted with the cost effectiveness and accessibility of the Internet.     

Human Immune Proteome in Experimental Colonization with Staphylococcus aureus

More than 20% of adults are persistently colonized with Staphylococcus aureus. When hospitalized, these carriers have increased risks of infection with their own strains. However, a recent study demonstrated a lower incidence of bacteremia-related death among carriers than among noncarriers, raising the question whether the adaptive immune system plays a protective role. In fact, S. aureus carriers mount a highly specific neutralizing antibody response against superantigens of their colonizing strains. We now used 2-dimensional immunoblotting to investigate the profiles of antibodies from healthy individuals against S. aureus extracellular proteins. Moreover, we tested whether symptom-free experimental colonization of these individuals with an S. aureus strain of low virulence, 8325-4, is sufficient to induce an antibody response. Sera obtained before and 4 weeks after colonization were screened for immunoglobulin G (IgG) antibody binding to extracellular staphylococcal proteins. At baseline, most volunteers harbored IgG directed against conserved virulence factors, including alpha-hemolysin (Hla), beta-hemolysin (Hlb), phospholipase C (Plc), staphylococcal serine protease (SspA), and cysteine protease (SspB). However, the variability of spot patterns and intensities was striking and could be important in case of infection. Experimental nasal colonization with S. aureus 8325-4 did not elicit new antibodies or boost the humoral response. Thus, the high antibody prevalence in humans is likely not induced by short-term nasal colonization, and presumably minor infections are required to trigger anti-S. aureus antibody responses.Staphylococcus aureus is one of the most common causes of nosocomial infection, and the species is becoming increasingly resistant to antibiotics (2). Apart from being a major human pathogen, S. aureus is also a frequent colonizer of human skin and mucosa (34). The bacteria find their primary ecological niche in the human nose but are also able to colonize the throat, the intestines, and the perineal region, sometimes exclusively (1, 17). Approximately 20% of the adult population carry S. aureus in the nose persistently, and another 30% carry it intermittently, frequently only for a few days, whereas 50% are noncarriers (NC) (29, 30, 34). Nasal carriers stand an increased risk of developing severe S. aureus infections caused by their autologous strains, especially upon hospitalization or immune suppression (32, 35). This underlines the fact that host and environmental factors play a decisive role in determining the outcome of S. aureus host interactions.In a recent large prospective study, carriers acquired S. aureus bacteremia more frequently than NC but, surprisingly, had a better survival rate than NC (35). This observation raises the question whether the adaptive immune system establishes immunity to the colonizing S. aureus strain, which could be of advantage in autologous infections. In support of this hypothesis, our group recently showed that S. aureus carriers raise a strong and strain-specific antibody response against the superantigen cocktail produced by their colonizing strain (12). However, S. aureus produces a broad repertoire of virulence factors, and the antibody response against superantigens is likely only the tip of an iceberg (8). In fact, anti-S. aureus antibodies against staphylococcal toxins, immune evasion molecules, and adhesins have been detected in healthy individuals as well as in patients (6, 7, 11, 31).Virulence factor expression is strictly regulated in S. aureus. While adhesins are expressed by bacterial cells in logarithmic growth, the majority of known virulence factors, including most superantigens but also cytolytic toxins, proteases, lipases, and several immune evasion molecules, are secreted in the post-exponential-growth phase (23, 38). In contrast to intracellular and cell wall-associated proteins, secreted virulence factors can act systemically while bacteria remain localized. Consequently, these factors are the most likely stimuli of the adaptive immune system during epithelial colonization with S. aureus (28).To date, a comprehensive investigation of anti-S. aureus antibody profiles from healthy individuals and their variability is still lacking. Moreover, it remains unknown which conditions (e.g., nasal colonization, minor or major infections) are required to trigger an antibody response against S. aureus. Therefore, we experimentally colonized the nares of 16 healthy human volunteers with S. aureus (36) and compared the anti-S. aureus antibody profiles before and 28 days after colonization. Our aims were to analyze the variability of the anti-S. aureus antibody profiles and to test whether experimental nasal colonization elicits or boosts an antibody response.     

Evolution of Helicobacter pylori susceptibility to antibiotics during a 10‐year period in Lithuania

The study evaluated the changes in the prevalence of Helicobacter pylori strains with primary resistance to antibiotics during the last 10 years in Lithuania. H. pylori susceptibilities to antibiotics were tested in 89 patients in 1998, in 81 patients in 2001 and in 90 patients in 2007/2008. Susceptibility to metronidazole, clarithromycin, amoxicillin and tetracycline was tested using E‐test or agar dilution method. Susceptibility to ciprofloxacin was only tested in 2007/2008. Data about utilization of all authorized and available on market macrolides and clindamycin in Lithuania during 2003–2007 were evaluated using WHO ATC/DDD methodology. A total of 260 H. pylori strains cultured from untreated adult patients were investigated. Primary resistance rates (1998, 2001 and 2007/2008) for metronidazole were 24.7%, 33.3%, and 35.6%, for clarithromycin 1.1%, 3.7%, and 3.3% and for tetracycline 0%, 2.5% and 0% respectively. No cases of amoxicillin resistance have been detected. The resistance rate for ciprofloxacin was 5.6% in 2007/2008. Data of total macrolides and clarithromycin utilization in Lithuania revealed that despite an increase of consumption of these drugs in Lithuania during 2003–2007 in 1.5 times, the total macrolide consumption remains one of the lowest in Europe. We have not observed any significant changes in the susceptibility of H. pylori to the most widely used antibiotics during the recent 10‐year period. The low resistance rate to clarithromycin might be related to the policy to avoid use of macrolides as first‐line treatment for pulmonary and other infections.