Optimization of polyvinylidene fluoride (PVDF) membrane fabrication for protein binding using statistical experimental design.

Statistical experimental design was employed to optimize the preparation conditions of polyvinylidenefluoride (PVDF) membranes. Three variables considered were polymer concentration, dissolving temperature, and casting thickness, whereby the response variable was membrane-protein binding. The optimum preparation for the PVDF membrane was a polymer concentration of 16.55 wt%, a dissolving temperature of 27.5°C, and a casting thickness of 450 µm. The statistical model exhibits a deviation between the predicted and actual responses of less than 5%. Further characterization of the formed PVDF membrane showed that the morphology of the membrane was in line with the membrane-protein binding performance.

Eosinophilic gastroenteritis: Clinical profiles and treatment outcomes, a retrospective study of 18 adult patients in a Singapore Tertiary Hospital.

BACKGROUND: Eosinophilic gastroenteritis (EG) can mimic symptoms of common gastrointestinal (GI) disorders but responds well to appropriate treatment. Accurate diagnosis is central to effective management. Data on EG in Southeast Asia is lacking. We aim to describe the clinical profiles and treatment outcomes of adult patients with EG in a Singapore Tertiary Hospital. MATERIALS AND METHODS: This retrospective study involved archival search of patients with GI biopsies that showed eosinophilic infiltration from January 2004 to December 2012. Patients' clinical data from computerised hospital records and clinical notes was reviewed. Diagnostic criteria for EG included presence of GI symptoms with more than 30 eosinophils/high power field on GI biopsies. Patients with secondary causes for eosinophilia were excluded. RESULTS: Eighteen patients with EG were identified (mean age 52 years; male/female: 11/7). Fifteen patients (83%) had peripheral blood eosinophilia. Seven patients (39%) had atopic conditions. Most common symptoms were diarrhoea and abdominal pain. Small intestine was the most common site involved. Endoscopic finding was non-specific. Ten patients were treated with corticosteroids (nine prednisolone, one budesonide): eight patients (89%) responded clinically to prednisolone but four patients (50%) relapsed following tapering-off of prednisolone and required maintenance dose. One patient each responded to diet elimination and montelukast respectively. Half of the remaining six patients who were treated with proton-pump inhibitors, antispasmodic or antidiarrheal agents still remained symptomatic. CONCLUSION: Prednisolone is an effective treatment though relapses are common. Small intestine is most commonly involved. EG should be considered in the evaluation of unexplained chronic recurrent GI symptoms.

Electrophoretic interactions between nitrocellulose membranes and proteins: Biointerface analysis and protein adhesion properties.

Protein adsorption onto membrane surfaces is important in fields related to separation science and biomedical research. This study explored the molecular interactions between protein, bovine serum albumin (BSA), and nitrocellulose films (NC) using electrokinetic phenomena and the effects of these interactions on the streaming potential measurements for different membrane pore morphologies and pH conditions. The data were used to calculate the streaming ratios of membranes-to-proteins and to compare these values to the electrostatic or hydrophobic attachment of the protein molecules onto the NC membranes. The results showed that different pH and membrane pore morphologies contributes to different protein adsorption mechanisms. The protein adsorption was significantly reduced under conditions where the membrane and protein have like-charges due to electrostatic repulsion. At the isoelectric point (IEP) of the protein, the repulsion between the BSA and the NC membrane was at the lowest; thus, the BSA could be easily attached onto the membrane/solution interface. In this case, the protein was considered to be in a compact layer without intermolecular protein repulsions.

Biochemical and functional characterization of a recombinant monomeric factor VIII-Fc fusion protein.

BACKGROUND: Hemophilia A results from a deficiency in factor VIII activity. Current treatment regimens require frequent dosing, owing to the short half-life of FVIII. A recombinant FVIII-Fc fusion protein (rFVIIIFc) was molecularly engineered to increase the half-life of FVIII, by 1.5-2-fold, in several preclinical animal models and humans. OBJECTIVE: To perform a biochemical and functional in vitro characterization of rFVIIIFc, with existing FVIII products as comparators. METHODS: rFVIIIFc was examined by utilizing a series of structural and analytic assays, including mass spectrometry following lysyl endopeptidase or thrombin digestion. rFVIIIFc activity was determined in both one-stage clotting (activated partial thromboplastin time) and chromogenic activity assays, in the context of the FXase complex with purified components, and in both in vitro and ex vivo rotational thromboelastometry (ROTEM) assays performed in whole blood. RESULTS: rFVIIIFc contained the predicted primary structure and post-translational modifications, with an FVIII moiety that was similar to other recombinant FVIII products. The von Willebrand factor-binding and specific activity of rFVIIIFc were also found to be similar to those of other recombinant FVIII molecules. Both chromogenic and one-stage assays of rFVIIIFc gave similar results. Ex vivo ROTEM studies demonstrated that circulating rFVIIIFc activity was prolonged in mice with hemophilia A in comparison with B-domain-deleted or full-length FVIII. Clot parameters at early time points were similar to those for FVIII, whereas rFVIIIFc showed prolonged improvement of clot formation. CONCLUSIONS: rFVIIIFc maintains normal FVIII interactions with other proteins necessary for its activity, with prolonged in vivo activity, owing to fusion with the Fc region of IgG(1) .

Investigating membrane morphology and quantity of immobilized protein for the development of lateral flow immunoassay.

This study was aimed at gaining a quantitative understanding of the effect of protein quantity and membrane pore structure on protein immobilization. The concentration of immobilized protein was measured by staining with Ponceau S and measuring its color intensity. In this study, both membrane morphology and the quantity of deposited protein significantly influenced the quantity of protein immobilization on the membrane surface. The sharpness and intensity of the red protein spots varied depending on the membrane pore structure, indicating a dependence of protein immobilization on this factor. Membranes with smaller pores resulted in a higher color density, corresponding to enhanced protein immobilization and an increased assay sensitivity level. An increased of immobilized volume has a significant jagged outline on the protein spot but, conversely, no difference in binding capacity.

Tuberculous biliary stricture.

Tuberculosis (TB) of the hepatobiliary system is not uncommon, but as a cause of biliary strictures, it is very rare. It poses difficulty in diagnosis and often requires surgical intervention to exclude underlying malignancy. To our knowledge, there are fewer than 20 reported cases in the English literature. We report a 35-year-old Filipino woman who presented with a 3-day history of obstructive jaundice, associated with significant weight loss and anorexia. Computed tomography (CT) revealed dilated intrahepatic biliary system secondary to distal stricture at the confluence of the left and right bile ducts. Magnetic resonance cholangiopancreatography characterised the lesion as an irregular stricturing at several sites in the common bile duct. Incidentally, the scans also showed indeterminate pulmonary nodules in the right lower lobes. CT thorax confirmed bilateral involvement of the lungs. She required percutaneous transhepatic drainage for biliary decompression. Tests on tissue from the lung lesions, the blood, and the bile all confirmed the presence of TB. She was treated with anti-TB medication. This report emphasizes the importance of considering TB as a possibile cause of biliary stricture, especially in South-East Asia.

Interaction of isothermal phase inversion and membrane formulation for pathogens detection in water.

The aim of this study was to explore the utilization of polymeric membrane for bio-sensing application in most efficient and rapid way. Customization of membrane formulation via phase separation study to modify its morphologies and properties enable the detection of different pathogens in a specific manner. Experimental findings (FESEM, through-pore distribution, porosity, capillary flow test and protein binding test) verified the predictions of faster capillary flow time and higher membrane's protein binding by the addition of cellulose acetate and nitrocellulose to the membrane casting dope, respectively. Throughout the phase separation study, the potential phase behavior was investigated, which was correlating various membrane structures to its performances for potential pathogens detection in water.

Natural orifice transgastric endoscopic wedge hepatic resection in an experimental model using an intuitively controlled master and slave transluminal endoscopic robot (MASTER).

BACKGROUND: The lack of triangulation of standard endoscopic devices limits the degree of freedom for surgical maneuvers during natural orifice transluminal endoscopic surgery (NOTES). This study explored the feasibility of adapting an intuitively controlled master and slave transluminal endoscopic robot (MASTER) the authors developed to facilitate wedge hepatic resection in NOTES. METHODS: The MASTER consists of a master controller, a telesurgical workstation, and a slave manipulator that holds two end-effectors: a grasper, and a monopolar electrocautery hook. The master controller is attached to the wrist and fingers of the operator and connected to the manipulator by electrical and wire cables. Movements of the operator are detected and converted into control signals driving the slave manipulator via a tendon-sheath power transmission mechanism allowing nine degrees of freedom. Using this system, wedge hepatic resection was performed through the transgastric route on two female pigs under general anesthesia. Entry into the peritoneal cavity was via a 10-mm incision made on the anterior wall of the stomach by the electrocautery hook. Wedge hepatic resection was performed using the robotic grasper and hook. Hemostasis was achieved with the electrocautery hook. After the procedure, the resected liver tissue was retrieved through the mouth using the grasper. RESULTS: Using the MASTER, transgastric wedge hepatic resection was successfully performed on two pigs with no laparoscopic assistance. The entire procedure took 9.4 min (range, 8.5-10.2 min), with 7.1 min (range, 6-8.2 min) spent on excision of the liver tissue. The robotics-controlled device was able to grasp, retract, and excise the liver specimen successfully in the desired plane. CONCLUSION: This study demonstrated for the first time that the MASTER could effectively mitigate the technical constraints normally encountered in NOTES procedures. With it, the triangulation of surgical tools and the manipulation of tissue became easy, and wedge hepatic resection could be accomplished successfully without the need for assistance using laparoscopic instruments.

Master and slave transluminal endoscopic robot (MASTER) for natural orifice transluminal endoscopic surgery (NOTES).

Although the flexible endoscopy has been widely used in the medical field for many years, there is still great potential in improving the endoscopist's capability to perform therapeutic tasks. Tentatively, tools for the flexible endoscope have poor maneuverability and limited Degree Of Freedom (DOF). In this paper, we propose a surgical robotic system MASTER (Master And Slave Transluminal Endoscopic Robot). MASTER is a dexterous and flexible master-slave device which can be used in tandem with a conventional flexible endoscope. Using this robotic system, ESD (Endoscopic Submucosal Dissection) and NOTES (Natural Orifice Transluminal Endoscopic Surgery) have been conducted on in vivo and ex vivo animal trials with promising results.

Imaging features of hepatic angiomyolipomas.

We review the imaging appearances of hepatic angiomyolipomas in patients with and without tuberous sclerosis. Sporadic hepatic angiomyolipomas have a varied appearance because of the inconstant proportion of fat, making confident imaging diagnosis difficult and necessitating biopsy in many cases. In patients with tuberous sclerosis, hepatic angiomyolipomas have a more consistent imaging appearance and, together with other features of the syndrome, can be more easily diagnosed. Preoperative diagnosis helps obviate unnecessary surgery.

Robotic system for no-scar gastrointestinal surgery.

INTRODUCTION: Flexible endoscopy allows diagnostic and therapeutic interventions on the gastrointestinal (GI) tract. Simple procedures can be performed endoscopically using currently available tools. More advanced endoscopic surgical interventions are much desired and anticipated, yet they await improvements in instrumentation. METHODS: Presented here is a master-slave robotic system designed for use with flexible endoscopy. The slave is a cable-driven flexible robotic manipulator that can be attached to an endoscope, allowing two-handed endoscopic manipulation with 9-12 degrees of freedom (DOF). RESULTS: Feasibility has been demonstrated in a porcine intragastric model. CONCLUSIONS: Further studies should determine whether this novel device can overcome some of the instrumentation-related challenges that have heretofore limited the development of natural orifice transluminal endoscopic surgery.

Possible role of gadolinium in nephrogenic systemic fibrosis: report of two cases and review of the literature.

Nephrogenic systemic fibrosis/nephrogenic fibrosing dermopathy (NSF/NFD) is a rare fibrosing disorder that occurs in patients with renal failure. It is associated with significant mortality and morbidity. Patients typically present with painful or pruritic indurated plaques involving the limbs and trunk, with sparing of the face. Severity and rapidity of cutaneous progression correlate with poorer prognosis. To date, the management of NSF/NFD remains anecdotal. The aetiological link in NSF/NFD is also yet to be confirmed, but renal dysfunction seems a common feature. Following recent reports of a possible causative role of gadolinium, we present two patients with histologically confirmed NSF/NFD, who had exposure to gadolinium-containing contrast agents 1-2 months before onset of disease. Severity of renal impairment, lack of immediate dialysis after exposure and cumulative dose of gadolinium are possible factors influencing the development of NSF/NFD. The process of transmetallation of gadolinium chelates may occur in patients with renal impairment, leading to precipitation of free gadolinium in the dermis or other organs, causing tissue injury that ultimately leads to the clinical manifestations of NSF/NFD. Although the causative role is not proven, gadolinium-containing contrast agents should be used only if clearly necessary in patients with renal failure.

Master-slave robotic system for therapeutic gastrointestinal endoscopic procedures.

Flexible endoscopy is used to inspect and treat disorders of the gastrointestinal (GI) tract without the need for creating an artificial opening on the patient's body. Simple surgical procedures (like polypectomy and biopsy) can be performed by introducing a flexible tool via a working channel to reach the site of interest at the distal end. More technically demanding surgical procedures like hemostasis for arterial bleeding, or suturing to mend a perforation cannot be effectively achieved with flexible endoscopy. The proposed robotic system enables the endoscopist to perform technically demanding therapeutic procedures (currently possible only with open surgery) in conjunction with conventional flexible endoscopes. The robotic system consists of a master console and a slave. The latter is a cable driven flexible robotic manipulator that can be inserted into tool channel of existing endoscopes or attached in tandem to the endoscopes. Together with the real time endoscopic view, the endoscopist would be capable of performing more intricate and difficult surgical procedures.

Detection of thyroid malignancy in a hot nodule by fluorine-18-fluorodeoxyglucose positron emission tomography.

Carcinoma of the thyroid arising in an autonomously functioning or "hot" nodule is uncommon. The majority of thyroid carcinomas present as a "cold" nodule on radionuclide scintigraphy. We report a poorly-differentiated thyroid carcinoma developing in a long-standing "hot" nodule in a 51-year-old Chinese woman. Fluorine-18-fluorodeoxyglucose positron emission tomography (FDG PET) showed focal FDG uptake in the thyroid nodule, as well as in the cervical and pulmonary hilar lymph nodes. This case illustrates that the incidence of thyroid carcinoma in a "hot" nodule is not negligible. The role of FDG PET in the differentiation of benign from malignant thyroid nodules is still unclear. In contrast, FDG PET has been shown to have a role in the follow-up of thyroid cancer patients after thyroidectomy and subsequent radioactive iodine-131 (I-131) ablation. It may be useful in the identification and localisation of recurrent cancer foci in patients with elevated thyroglobulin levels but a negative I-131 whole body scan.

Oral and pulmonary delivery of FSH-Fc fusion proteins via neonatal Fc receptor-mediated transcytosis.

BACKGROUND: The alpha and beta subunits of FSH were fused to the Fc domain of IgG1 either in a single chain or a heterodimer format. These molecules were absorbed through the epithelium in lung and intestine by neonatal Fc receptor (FcRn)-mediated transcytosis. METHODS AND RESULTS: Single chain and heterodimer FSH-Fc were made recombinantly in Chinese hamster ovary cells. Treatment of rats with a single s.c. dose of single chain or heterodimer FSH-Fc resulted in greater stimulation of ovarian weight (20.8+/-3.9 and 26.9+/-6.1 mg respectively) compared to those receiving vehicle (12.1+/-1.0 mg) or an equimolar dose of recombinant human FSH (14.3+/-1.7 mg). Both FSH-Fc fusion proteins were absorbed after oral dosing of newborn rats with long terminal half-lives of approximately 60 h, and pulmonary delivery in four cynomolgus monkeys produced maximum serum concentrations between 69 and 131 ng/ml with long terminal half-lives between 55 and 210 h. Serum inhibin levels increased after pulmonary dosing with single chain FSH-Fc (1.3- and 1.4-fold) and heterodimer FSH-Fc (5.9- and 7.1-fold) and remained elevated for >12 days after treatment with heterodimer FSH-Fc. CONCLUSIONS: We have shown that FSH-Fc fusion proteins have increased stability in blood and improved bioactivity in vivo, and that heterodimer FSH-Fc is more active in rats and monkeys than single chain FSH-Fc. These data suggest that Fc fusion proteins offer the potential for oral and pulmonary delivery of FSH.

Paratubal cyst complicated by tubo-ovarian torsion: computed tomography features.

Paratubal cysts complicated by tubo-ovarian torsion are an uncommon cause of acute right iliac fossa pain in children and very rarely diagnosed accurately preoperatively. We report a constellation of diagnostic CT features in a 12-year-old pubertal girl.

A case of cystic leiomyoma mimicking an ovarian malignancy.

INTRODUCTION: We report an unusual case of a large cystic, pedunculated uterine leiomyoma mimicking a primary malignant ovarian tumour on sonography and computed tomography (CT). CLINICAL PICTURE: A 56-year-old post-menopausal woman presented with a right pelviabdominal mass. Sonography and CT examination showed a large extrauterine mass arising from the right adnexa and extending into the abdomen. The mass was predominantly cystic with a solid component at the periphery. A preoperative diagnosis of a primary malignant ovarian tumour was made. TREATMENT: The patient underwent laparotomy. The large mass was found to arise from the uterine fundus; the ovary was not involved. The mass was resected, followed by total hysterectomy and bilateral salpingo-oophorectomy. Histology was that of a leiomyoma with extensive cystic degeneration. OUTCOME: The patient made an uneventful recovery. CONCLUSION: A pedunculated, subserosal uterine leiomyoma with extensive cystic degeneration can mimic an ovarian tumour on imaging and should be considered in the differential diagnosis of an adnexal mass.