Immobilization of amyloglucosidase onto macroporous cryogels for continuous glucose production from starch

Poly(methyl methacrylate-glycidyl methacrylate) [Poly(MMA-GMA)] cryogels were synthesized using monomers of methylmethacrylic acid and epoxy group bearing GMA via radical cryopolymerization technique. Synthesized cryogels were used for the immobilization of amyloglucosidase to the cryogel surface using epoxy chemistry. Characterizations of the free and immobilized amyloglucosidase were carried out by comparing the optimum and kinetic parameters of enzymes. For this, pH and temperature profiles of free and immobilized preparation were studied and, it was found that, optimum pH of enzyme was not change upon immobilization (pH 5.0), while optimum temperature of the enzyme shifted 10 °C to warmer region after immobilization (optimum temperatures for free and immobilized enzyme were 55 and 65 °C, respectively). Kinetic parameters of free and immobilized enzyme were also investigated and K_m values of free and immobilized amyloglucosidase were found to be 2.743 and 0.865 mg/mL, respectively. V_max of immobilized amyloglucosidase was found to be (0.496 µmol/min) about four times less than that of free enzyme (2.020 µmol/min). Storage and operational stabilities of immobilized amyloglucosidase were also studied and it was showed that immobilized preparation had much more stability than free preparation. In the present work, amyloglucosidase immobilized poly(MMA-GMA) cryogels were used for continuous glucose syrup production from starch for the first time. Efficiency of immobilized enzyme was investigated and released amount of glucose was found to be 2.54 mg/mL at the end of the 5 min of hydrolysis. The results indicate that the epoxy functionalized cryogels offer a good alternative for amyloglucosidase immobilization applications with increased operational and thermal stability, and reusability. Also, these cryogels can be used for immobilization of other industrially valuable enzymes beyond amyloglucosidase.     

Short-term effects of partial meniscectomy on the clinical results of anterior cruciate ligament reconstruction

Purpose

This study aims to analyse the short-term effects of partial meniscectomy on the clinical results of anterior cruciate ligament reconstruction surgery.

Methods

Clinical outcomes of 19 patients who had partial medial meniscectomy and anterior cruciate ligament reconstruction during the same surgery (Group 1) were compared with the outcomes of 25 patients who had also reconstruction but did not have any meniscal lesion (Group 2). Median follow-up time was 29 months (range 12–67 months) in Group 1 and 27 months (range 12–70 months) in Group 2. Feeling of apprehension in sports activities, International Knee Documentation Committee (IKDC) score, KT-2000 Arthrometer^® measurements and post-operative time to return to sports activity were the criteria for data analysis.

Results

Eight patients (42 %) in Group 1 and 5 patients (20 %) in Group 2 stated feeling of apprehension in sports activities. IKDC score improved to A in 11 patients (58 %) from Group 1, and 18 patients (72 %) from Group 2. Mean anterior translation according to KT-2000 arthrometer measurements was 5.2 ± 1.3 mm in Group 1, and 4.6 ± 1.3 mm in Group 2. Post-operative time to return to sports activity was 8.5 ± 3.0 months in Group 1, and 6.5 ± 2.2 months in Group 2.

Conclusion

Partial meniscectomy for irreparable medial meniscal tears, applied during the same surgery with anterior cruciate ligament reconstruction, negatively affects the clinical outcomes in the short-term follow-up. This study may be a reference for long-term clinical trials and also future investigations of new methods in the treatment of similar cases.

Level of evidence

IV.

     

Immediate primary anastomosis for isolated oesophageal atresia: A single-centre experience

Background:

Isolated oesophageal atresia without tracheo-oesophageal fistula represents a major challenge for most paediatric surgeons. Here, we present our experience with six neonates with isolated oesophageal atresia who successfully underwent immediate primary anastomosis using multiple Livaditis circular myotomy.

Materials and Methods:

All six neonates were gross type A isolated oesophageal atresia (6%), from among 102 neonates with oesophageal atresia, treated between January 2009 and December 2013. Five neonates were female; one was male. The mean birth weight was 2300 (range 1700-3100) g.

Results:

All six neonates successfully underwent immediate primary anastomosis using multiple myotomies (mean 3; range 2-4) within 10 (median 3) days after birth. The gap under traction ranged from 6 to 7 cm. One neonate died of a major cardiac anomaly. Another neonate was lost to follow-up after being well for 3 months. Three anastomotic strictures were treated with balloon dilatation, and four anastomotic leaks were treated conservatively. The mean duration of follow-up was 33 months.

Conclusions:

To treat isolated oesophageal atresia, an immediate primary anastomosis can be achieved using multiple myotomies. Although, this approach is associated with high complication rates, as are other similar approaches, these complications can be overcome.Key words: Anastomotic leak, anastomotic stricture, isolated oesophageal atresia, long-gap oesophageal atresia, myotomy     

Levosimendan has an inhibitory effect on platelet function

Levosimendan enhances cardiac contractility by increasing myocyte sensitivity to calcium, and induces vasodilatation. Although studies have evaluated the efficacy of levosimendan in heart failure, it is not clear whether it might produce functional influence on platelet response. In this study, the effect of levosimendan on platelet aggregation was investigated. Platelet function tests were performed in 12 healthy male volunteers. Three concentrations of levosimendan solution were prepared that would result in 10, 25, and 45 ng/ml levosimendan concentrations in the blood similar to that observed after clinical therapeutic intravenous application of 0.05-0.1 microg/kg/min. Each concentration of levosimendan solution and a control diluent without levosimendan were incubated with whole blood at 37 degrees C. After incubation for 15 min, aggregation responses were evaluated with adenosine diphosphate (ADP) (5 and 10 microM) and collagen (2 and 5 microg/ml) in platelet-rich plasma. Preincubation with all dilutions of levosimendan inhibited aggregation of platelets induced by ADP and collagen significantly. Levosimendan also inhibited significantly the secondary wave of platelet aggregation induced by ADP. The results showed that there was a relationship between levosimendan concentration and inhibition of platelet aggregation. In conclusion, this study with an in vitro model showed that levosimendan had a significant inhibitory effect on platelets in clinically relevant doses.     

Is there a role for surgery in the management of isolated secundum atrial septal defect in adults?

Isolated atrial septal defect (ASD) is the most common form of congenital heart abnormalities in adults and approximately 80% are located in the region of the fossa ovalis (ostium secundum ASD).1 Indications for closure are in cases where the ratio of pulmonary-to-systemic flow (Qp/Qs) is higher than 1.5, without significant elevation of pulmonary vascular resistance.Surgical closure of ASDs has been performed for over 60 years and techniques have steadily improved, using smaller incisions and minimally invasive techniques. On the other hand, in the last 20 years, various transcatheter ASD closure techniques and devices have been developed, among which, percutaneous treatment with a septal occluder device is the most popular.2,3Despite increasing use of occluder devices and the fact that studies have been published internationally pointing out some of the advantages and disadvantages compared with surgery in adults, no formal comparison of efficacy, morbidity and complications has been published.2-4 We present a retrospective comparison of short-term (three months) results for transcatheter and surgical closure of 163 ostium secundum ASD patients in a university hospital.     

Fluoroscopic balloon dilatation for caustic esophageal stricture in children: An 8-year experience

Purpose

Esophageal balloon dilatation (EBD), when performed early and correctly, can efficiently treat caustic esophageal stricture (ES). Herein, we present 8 years of experience treating caustic ES, and discuss the technique as well as the complications.

Methods

We retrospectively reviewed the medical records of 38 children in whom we performed fluoroscopic EBD under general anesthesia for caustic ES between November 2004 and November 2012 in our hospitals. The patients were grouped into the early dilatation group, who began EBD earlier (mean, 15 days) after caustic ingestion, and the late dilatation group who was referred later (mean, 34 days) for EBD by other centers. The ESs were classified into short and long strictures. Balloon size was increased gradually to a sufficient diameter over consecutive sessions. Characteristics of patients and ES, details of the EBD, and treatment results were analyzed.

Results

A total of 369 EBD sessions were successfully performed in 38 children (aged 14 months to 14 years, median 3.5 years). In six patients, EBD treatments are continuing, one patient was lost to follow up, one patient who received a stent was excluded, and three returned to their previous centers. The remaining 27 patients were treated successfully by repeated EBD treatments. Nevertheless, in the early dilatation group (n = 16), EBD treatment was significantly faster and shorter than that in the late dilatation group (n = 11). In addition, the short stricture treatment was also of significantly shorter duration than the long stricture treatment. Six (1.6%) esophageal perforations occurred in five patients (13.2%); all were treated conservatively. There was no mortality.

Conclusions

For treatment of caustic ES, fluoroscopically guided EBD is safe and has a low rate of complications as well as a 100% success rate. However, it should be begun earlier, and in children, should be performed gently with balloons of gradually increasing appropriate diameters over consecutive sessions.