Modeling atomic force microscopy and shell mechanical properties estimation of coated microbubbles

We present an extensive comparison with experimental data of our theoretical/numerical model for the static response of coated microbubbles (MBs) subject to compression from an atomic force microscope (afm). The mechanics of the MB's coating is described in the context of elastic thin shell theory. The encapsulated fluid is treated as compressible/incompressible pertaining to a gas/liquid, while the thinning of the liquid film between the MB and the afm cantilever is modeled via introduction of an interaction potential and the resulting disjoining pressure. As the external force increases, the experimental force-deformation (f-d) curves of MBs covered with polymer have an initial linear response (Reissner regime), followed by a non-linear curved downwards response (Pogorelov regime) where buckling takes place. On the other hand, the f-d curve for MBs covered with lipid monolayers initially follows the Reissner regime, but buckling is bypassed to a curved upwards regime where internal gas pressure dominates. The elastic properties, namely Young's modulus and shell thickness, for MB's covered with polymer can be estimated by combining the buckling point and the slope of the Reissner regime or the slopes of Reissner and Pogorelov regimes. Comparison of the present model with afm f-d curves for polymer shows satisfactory agreement. The area dilatation and bending moduli are shown to be the appropriate independent elastic parameters of MBs covered with phospholipid monolayers and are estimated by combination of the transition from Reissner to pressure dominated regime. Simulations and experiments in this case are in excellent agreement.

Simulated performance of flexible sigmoidoscopy-based screening for advanced neoplasia detection in a Greek population

BACKGROUND

Flexible sigmoidoscopy (FS) is resource-conserving and may increase adherence to colorectal cancer (CRC) screening compared to total colonoscopy. We investigated the diagnostic performance of FS-based screening for advanced colorectal neoplasia (ACN), including advanced adenomatous neoplasms (AANs), advanced serrated lesions (ASLs) and CRCs.

METHODS

Data from 2005 subjects undergoing average-risk screening colonoscopy in a single center in Greece were retrospectively reviewed. Sensitivities of FS-based screening for detecting AANs, ASLs, CRCs or any ACN were simulated on a per-lesion basis, assuming: 1) FS up to the sigmoid-descending junction (FS-1) or splenic flexure (FS-2); 2) colonoscopy referral criteria according to the 4 screening FS trials conducted in UK, Italy, Norway, and USA.

RESULTS

Overall, 114 ACNs (93 AANs, 17 ASLs, 4 CRCs) were detected in 102 (5.1%) subjects. The overall sensitivities of FS-1 and FS-2 alone for the detection of any ACN were 41.2% and 54.4%, respectively. Assuming different colonoscopy referral criteria, the estimated sensitivities for any ACN ranged from 48.2-50.9% for FS-1 and 60.5-64% for FS-2. The overall sensitivities were lower for ASLs (FS-1: 35.3-41.2%, FS-2: 41.2-52.9%) compared to those observed for AANs (FS-1: 48.4-51.6%, FS-2: 62.4-66.7%). The difference was particularly pronounced in women, in whom all 4 criteria led equally to a very low sensitivity for ASLs (30%).

CONCLUSIONS

Implementation of FS-based screening in Greek subjects would have led to the detection of 48-64% of all ACNs. An alarmingly low detection of ASLs among women may call for gender-specific colonoscopy referral strategies.

Management of difficult bile duct stones and indeterminate bile duct structures: Reduced ERCP radiation exposure with adjunct use of digital single-operator cholangioscopy

INTRODUCTION

Endoscopic Retrograde Cholangio-Pancreatography (ERCP) is an well-established endoscopic procedure for the management of biliary diseases. The use of fluoroscopy during ERCP has often raised concerns regarding potential risks from radiation exposure, particularly in complex cases. We investigated whether a new digital single-operator cholangioscopy (D-SOC) system, used adjunctively to ERCP, actually reduces patient radiation exposure.

MATERIALS AND METHODS

We retrospectively analyzed a prospective database (April 2016 to October 2018) including consecutive patients who underwent successful management of difficult-to-treat biliary stones or indeterminate biliary strictures by using either conventional ERCP (ERCP cohort) or ERCP in conjunction with D-SOC (ERCP/D-SOC cohort). The overall patient radiation exposure outcomes were compared in terms of Kerma Area Product (KAP), Fluoroscopy time (T) and the total number of films (F).

RESULTS

Overall, 47 patients (mean 71.8 years, 59.6% males) were included (ERCP cohort = 29, ERCP/D-SOC cohort = 18), referred either for difficult bile duct stones (n = 36) or indeterminate biliary strictures (n = 11). The median KAP, T and F in the ERCP/D-SOC cohort were 12.3 Gycm², 3.7 min and 4 films respectively, compared with 52.1 Gycm², 8.4 min, and 5 films respectively in the ERCP cohort. Statistically significant differences (P = 0.0001) were found for KAP and T.

CONCLUSIONS

Adjunct use of a digital cholangioscopy platform appears to significantly reduce radiation exposure in patients undergoing ERCP for the management of difficult bile stones or indeterminate biliary strictures.

Cold versus hot endoscopic mucosal resection for nonpedunculated colorectal polyps sized 6-10 mm: a randomized trial

BACKGROUND AND STUDY AIMS

Cold snare polypectomy is an established method for the resection of small colorectal polyps; however, significant incomplete resection rates still leave room for improvement. We aimed to assess the efficacy of cold snare endoscopic mucosal resection (CS-EMR), compared with hot snare endoscopic mucosal resection (HS-EMR), for nonpedunculated polyps sized 6 - 10 mm.

PATIENTS AND METHODS

This study was a dual-center, randomized, noninferiority trial. Consecutive adult patients with at least one nonpedunculated polyp sized 6 - 10 mm were enrolled. Eligible polyps were randomized (1:1) to be treated with either CS-EMR or HS-EMR. Both methods involved submucosal injection of a methylene blue-tinted normal saline solution. The primary noninferiority end point was histological eradication evaluated by postpolypectomy biopsies (noninferiority margin - 10 %). Secondary outcomes included occurrence of intraprocedural bleeding, clinically significant postprocedural bleeding, and perforation.

RESULTS

Among 689 patients screened, 155 patients with 164 eligible polyps were included (CS-EMR n = 83, HS-EMR n = 81). The overall rate of histological complete resection was 92.8 % in the CS-EMR group and 96.3 % in the HS-EMR group (difference 3.5 %; 95 % confidence interval [CI] - 4.15 to 11.56), showing noninferiority of CS-EMR compared with HS-EMR. CS-EMR was shown to be noninferior both for polyps measuring 6 - 7 mm (CS-EMR 93.3 %; HS-EMR 100 %; 95 %CI - 7.95 to 21.3) and those of 8 - 10 mm (92.5 % vs. 94.7 %, respectively; 95 %CI - 7.91 to 13.16). Rates of intraprocedural bleeding were similar between the two groups (CS-EMR 3.6 %, HS-EMR 1.2 %; P  = 0.30). No clinically significant postprocedural bleeding or perforation occurred in either group.

CONCLUSIONS

CS-EMR appears to be a valuable modification of the standard cold snare technique, obviating the need to use diathermy for nonpedunculated colorectal polyps sized 6 - 10 mm.

Seven-day genotypic resistance-guided triple Helicobacter pylori eradication therapy can be highly effective

BACKGROUND

The efficacy and applicability of molecular testing to guide the selection of antibiotics in triple Helicobacter pylori (H. pylori) eradication regimens have not been reported. We tested a 7-day, genotypic resistance-guided triple H. pylori eradication therapy in a high-resistance setting.

METHODS

Consecutive dyspeptic patients with H. pylori infection were prospectively enrolled. Genotypic resistances to clarithromycin (23SrRNA mutations) and fluoroquinolones (gyrA mutations) were determined from gastric biopsy specimens using a commercially available molecular assay (GenoTypeâ HelicoDR). A tailored genotypic resistance-guided 7-day triple therapy comprised esomeprazole, amoxicillin, and either clarithromycin (wild-type 23SrRNA), levofloxacin (23SrRNA mutated/wild-type gyrA) or rifabutin (both 23SrRNA/gyrA mutated). H. pylori eradication was confirmed by 13C-urea breath test.

RESULTS

Of 148 subjects screened, 51 patients were enrolled (male/female: 27/24, mean age: 50.7±11.4 years, treatment-naïve/-experienced: 32/19). The molecular kit was easily implemented, allowing for rapid (within 24 h) and relatively inexpensive determination of H. pylori resistance (clarithromycin: 47.1%, fluoroquinolones: 15.7%, dual clarithromycin/fluoroquinolones: 7.8%). For patients who received clarithromycin-, levofloxacin- and rifabutin-containing triple therapy, the respective eradication rates were 24/27, 20/20, and 2/4 by intention-to-treat (ITT); and 24/24, 19/19 and 2/3 by per-protocol (PP) analysis. Overall eradication rates were 90.2% (95% confidence interval [CI] 77.8-96.3%) by ITT and 97.8% (95%CI 87-99.8%) by PP analysis, showing no significant difference between treatment-naïve and -experienced patients (ITT: 87.5% vs. 94.7%, P=0.64; PP: 96.4% vs. 100%, respectively, P=1.00).

CONCLUSIONS

Regardless of prior treatment history, a genotypic resistance-guided 7-day triple therapy, based on a simple molecular assay, achieved a high H. pylori eradication rate.

When perforation is not the culprit : case report and systematic review of mechanical small-bowel obstruction complicating colonoscopy

Colonoscopy is generally safe, although expansion of colorectal cancer prevention programs is likely to increase the number of post-colonoscopy complications. We report the case of a 42-year old woman with a prior history of 2 cesarean section deliveries who developed abdominal pain after an otherwise uneventful screening colonoscopy. Urgent exploration revealed closed-loop obstruction involving the terminal ileum, caused by an adhesive band close to the site of her previous Pfannenstiel incision. A systematic review of the literature revealed 11 reports (1985-2008) describing a total of 13 cases of mechanical small bowel obstruction (MSBO) after colonoscopy, 9 of which were confirmed by laparotomy. Colonoscopy-induced MSBO is practically impossible to anticipate, and only a prior history of abdominal/pelvic surgery may be deemed as a predisposing factor. However, it is related to significant morbidity, as it often leads to an ischemic bowel with need for surgical resection. Thus, endoscopists should be aware and maintain a low operative threshold to this rare, but hazardous, complication of colonoscopy.

Experiences from the 2014 outbreak of bluetongue in Greece

Objective of this paper was to review relevant work and to present a general account of the bluetongue outbreak, which occurred in Greece in 2014. In total, 2895 outbreaks of the disease have been reported by the veterinary authorities of Greece; sheep, goats and cattle were affected with officially reported morbidity rates of 11.0%, 2.0% and 3.5%, respectively. No vaccinations were allowed and conservative measures were implemented to attempt to limit the disease, which at the end had expanded throughout the country. In field investigations, a significantly higher bluetongue morbidity rate (27.5%) in sheep has been reported. During that work, clinical anaemia was encountered, which was characterised as macrocytic, hypochromic, regenerative and non-haemolytic. Other investigations, which are reviewed in this paper, have described an outbreak of Citrobacter freundii-associated enteritis in newborn kids, offspring of goats subclinically infected with Bluetongue virus, increased rate of early embryonic deaths, reduced conception rates, increased incidence risk of mastitis and reduced milk yield in herds of subclinically-infected cattle and detection of the virus from hunter-harvested tissue samples of roe-deer. In 2015, vaccines against the disease have been licenced; vaccinations started in May 2015. Then, in 2015, only one outbreak of the disease was confirmed, which could have been the result of a combination of reasons acting concurrently to prevent further cases.

A delayed onset of bowel activity after the start of conventional polyethylene glycol predicts inadequate colon cleansing before colonoscopy: A prospective observational study

BACKGROUND

Evaluation of factors correlating with the quality of bowel preparation (QBP) is critical to ensure high-quality colonoscopy.

OBJECTIVES

We sought to determine whether the time interval between the start of conventional polyethylene glycol (PEG) ingestion and the onset of bowel activity is predictive of QBP.

METHODS

Consecutive adult outpatients attending colonoscopy were prospectively assessed. Data including demographics, medical history, time of starting/completion of PEG and time when bowel activity started were recorded. The QBP was assessed according to the Ottawa bowel preparation score (OBPS); inadequate QBP was OBPS ≥7.

RESULTS

A total of 171 patients (92 males, mean age: 60.5 years) complying with preparation instructions were included. The median OBPS was 5 (range: 1-13) and 57 (33.3%) had inadequate QBP. The median interval between the initiation of PEG and the onset of bowel activity was 60 min (range: 9-300 min). Patients (n = 52, 30.4%) with a delayed (>90 min) onset of bowel activity had poorer QBP (p = 0.0001). In multivariate analysis, male gender (OR: 2.38, p = 0.03), the interval between the end of preparation and the start of colonoscopy (OR: 1.94, p = 0.02) and time to onset of bowel activity >90 min (OR: 3.38, p = 0.004) were predictive of inadequate QBP.

CONCLUSION

The time interval between the initiation of PEG ingestion and the onset of bowel activity is predictive of the QBP. Our data support "on demand" intensification of bowel preparation in patients with a delayed onset of purgative response to PEG.

First evidence of Leishmania infection in European brown hare (Lepus europaeus) in Greece: GIS analysis and phylogenetic position within the Leishmania spp

Although the existence of a sylvatic transmission cycle of Leishmania spp., independent from the domestic cycle, has been proposed, data are scarce on Leishmania infection in wild mammals in Greece. In this study, we aimed to investigate the presence of Leishmania infection in the European brown hare in Greece, to infer the phylogenetic position of the Leishmania parasites detected in hares in Greece, and to identify any possible correlation between Leishmania infection in hares with environmental parameters, using the geographical information system (GIS). Spleen samples from 166 hares were tested by internal transcribed spacer-1 (ITS-1)-nested PCR for the detection of Leishmania DNA. Phylogenetic analysis was performed on Leishmania sequences from hares in Greece in conjunction with Leishmania sequences from dogs in Greece and 46 Leishmania sequences retrieved from GenBank. The Leishmania DNA prevalence in hares was found to be 23.49 % (95 % confidence interval (CI) 17.27-30.69). The phylogenetic analysis confirmed that the Leishmania sequences from hares in Greece belong in the Leishmania donovani complex. The widespread Leishmania infection in hares should be taken into consideration because under specific circumstances, this species can act as a reservoir host. This study suggests that the role of wild animals, including hares, in the epidemiology of Leishmania spp. in Greece deserves further elucidation.

A serosurvey for selected pathogens in Greek European wild boar

OBJECTIVES

Serum samples, collected from 94 European wild boar (Sus scrofa) during the hunting seasons 2006 -2010 from different regions of Greece, were examined in order to estimate the role of these wildlife species as reservoir of pathogens important for livestock and/or public health.

MATERIALS AND METHODS

The assays used for this purpose were commercial indirect ELISA for the detection of antibodies against porcine circovirus type 2 (PCV-2), porcine reproductive and respiratory syndrome (virus) (PRRSV), Aujeszky's disease virus (ADV), influenza A (IA) virus, Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae, Salmonella species, Trichinella species and indirect immunofluorescence antibody test for the detection of antibodies against Toxoplasma gondii and Neospora caninum.

RESULTS

Antibodies against PCV-2, PRRSV, ADV, IA virus,A. pleuropneumoniae, M. hyopneumoniae, Salmonella species, Trichinella species, T. gondii and N. caninum were detected in 19.1 per cent, 12.8 per cent, 35.1 per cent, 1.1 per cent, 57.4 per cent, 0 per cent, 4.3 per cent, 6.4 per cent, 5.2 per cent and 1.1 per cent of the samples, respectively. Cluster analysis revealed a hot spot of seropositivity near Bulgarian border; seropositivity to ADV was more common among female animals.

CONCLUSIONS

These results indicate exposure of wild boar to most of the above-mentioned pathogens, raising concern about the possibility that these species may pose a significant health risk for livestock and/or humans.

Bilateral spinal decompression of lumbar central stenosis with the full-endoscopic interlaminar versus microsurgical laminotomy technique: a prospective, randomized, controlled study

BACKGROUND

Extensive decompression with laminectomy, where appropriate, is often still described as the method of choice when operating on degenerative lumbar spinal stenosis. Nonetheless, tissue-sparing procedures are becoming more common. Endoscopic techniques have become the standard in many areas because of the surgical advantages they offer and the benefits for rehabilitation. One key issue when operating on the spine was the development of instruments to provide sufficient bone resection under continuous visual control. This was achieved by using endoscopes for operations carried out in cases of spinal canal stenosis.

OBJECTIVE

This study of patients with degenerative lumbar central spinal stenosis compares the results of spinal decompression using the full-endoscopic interlaminar technique (FI) with a conventional microsurgical laminotomy technique (MI).

STUDY DESIGN

Prospective, randomized, controlled study.

SETTINGS

135 patients with microsurgical or full-endoscopic decompression were followed up for 2 years. Alongside general and specific parameters, the following measuring instruments were also used for the investigation: Visual Analog Scale (VAS), German version of the North American Spine Society Instrument (NASS), Oswestry Low-Back-Pain-Disability Questionnaire (ODI).

RESULTS

Postoperatively 72 % of the patients no longer had leg pain or the pain was almost completely reduced and 21.2 % experienced occasional pain. The clinical results were the same in both groups. The rate of complications and revisions was significantly reduced in the FI Group. The full-endoscopic techniques brought advantages in the following areas: operation, complications, traumatization, rehabilitation.

LIMITATIONS

Lack of placebo control group.

CONCLUSIONS

The recorded results demonstrate that the full-endoscopic interlaminar bilateral decompression adopting a unilateral approach provides an adequate and safe supplement and alternative to the conventional microsurgical bilateral laminotomy technique when the indication criteria are fulfilled. At the same time, it offers the advantages of a minimally invasive intervention.

Poor endoscopic findings in children with non variceal upper gastrointestinal bleeding: is biopsy necessary?

BACKGROUND

Gastrointestinal bleeding in infants and children is a potentially serious condition in the practice of general pediatrics that requires investigation. The objective of this study is to describe the endoscopic and histopathological findings in children with upper gastrointestinal (UGI) bleeding of non variceal origin.

PATIENTS AND METHODS

We performed a retrospective study of the medical records of 181 children, aged 1 month to 15.2 years, with non variceal UGI bleeding, who were admitted in our department over the period 1988-2008 and underwent upper GI endoscopy accompanied by histology. Patients were divided in 4 groups according to their age (=0-1 years, = 1-6 years, C=6-12 years, D= 12-16 years).

RESULTS

An endoscopically evident bleeding source was detected in only 5% of all patients. Histological examination revealed increased incidence of eosinophilic infiltration in infants, in contrast to all other age groups, where non-specific or H. pylori related inflammation predominated. Peptic ulcer was found in 4.4% of all patients.

CONCLUSION

Although an evident bleeding source was detected in only a small percentage of patients, the accompanying histological examination provided additional information regarding possible underlying diseases and contributed to the subsequent therapeutic management.

Combined HLA-DR and -DQ disparity is associated with a stable course of ulcerative colitis after liver transplantation for primary sclerosing cholangitis

Combined disparity of human leukocyte antigen (HLA)-DR and -DQ between mother and fetus is associated with less severe ulcerative colitis (UC) during pregnancy. We evaluated whether donor-recipient HLA disparity after liver transplantation (LT) affects UC in patients with primary sclerosing cholangitis (PSC). Sixty-nine consecutive patients with PSC underwent LT; all underwent colonoscopy before LT; 48 had UC before and 3 had de novo UC after LT. Clinical and laboratory data, activity and treatment of UC, post-LT cytomegalovirus infection, and disparity of HLA-A, -B, -DR, and -DQ for each donor-recipient pair were evaluated. Pre-LT quiescent UC was present in 26 patients. Post-LT UC activity was evaluated in 36 of 51 patients with UC who had not undergone pre-LT colectomy and who had >12 months' post-LT survival. Of these, 16 were stable, 17 had worsened, and 3 had de novo UC. Seven required colectomy (4 for dysplasia or cancer) after LT. Post-LT cytomegalovirus viremia was neither associated with worse UC activity (P = 0.58) nor de novo UC. Disparity with respect to HLA-A, -B, -DR, and -DQ was found in 58%, 27%, 44%, and 39% donor-recipient pairs, respectively. Post-LT UC course was similar with respect to single HLA disparity. However, disparity in none or only one HLA-DR or -DQ was significantly associated with worse activity compared with patients with disparity at both (65% vs. 0%, P = 0.009). Logistic regression found that the disparity for both -DR and -DQ was the only factor statistically significantly associated with post-LT UC activity. We conclude that disparity in both HLA-DR and -DQ between donor and recipient is associated with stable UC activity after LT.