A rapid screening method to select microdialysis carriers for hydrophobic compounds

Microdialysis is a minimally invasive sampling technique which is widely applied in many fields including clinical studies. This technique usually has limitation on sampling hydrophobic compounds as aqueous solutions are commonly used as the perfusates. The relative recovery of hydrophobic compounds is often low and irreproducible because of the non-specific binding to microdialysis membranes or catheter tubing. Carriers such as cyclodextrins have been used to improve the recovery and consistency, however the identification of an optimal carrier can only be achieved after time-consuming and costly microdialysis experiments. We therefore developed a rapid, convenient, and low-cost method to identify the optimal carriers for sampling hydrophobic compounds with the use of centrifugal ultrafiltration. Doxorubicin was used as the model compound and its relative recoveries obtained from centrifugal ultrafiltration and from microdialysis were compared. The results show that the relative recoveries are highly correlated (correlation coefficient ≥ 0.9) between centrifugal ultrafiltration and microdialysis when different types or different concentrations of cyclodextrins were used as the carriers. In addition to doxorubicin, this method was further confirmed on three other drugs with different hydrophobicity. This method may facilitate and broaden the use of microdialysis perfusion on sampling or delivering hydrophobic substances in various applications.

Simultaneous injection‐aspiration technique of air/fluid exchange for in‐office treatment of post‐operative vitreous cavity hemorrhage

Background Post-operative vitreous cavity hemorrhage following pars plana vitrectomy is common. In-office drainage of the hemorrhage may be an option for some patients. Technique A new method for office-based air fluid exchange is described. A 30-gauge needle with a 10-mm syringe filled with sterile air is inserted 3.5-mm posterior to the limbus in the superotemporal quadrant. A second 30-gauge needle is inserted 3.5 mm from the limbus at 6 o’clock and connected to an empty 10-mm syringe with intravenous catheter tubing. The plunger of the air-filled syringe is pushed while the plunger of the empty syringe is pulled, so that the rate of fluid aspiration matches the rate of air injection. Discussion The method approximates conditions in pars plana vitrectomy, with balanced infusion and aspiration. Displaced vitreous cavity contents are collected in the aspiration syringe. The procedure is also cost effective. Conclusion The simultaneous syringe method is an easy, safe, and effective way of clearing post-operative vitreous cavity hemorrhage.

Lactobacillus acidophilus Derived Biosurfactant as a Biofilm Inhibitor: A Promising Investigation Using Microfluidic Approach

Background: Biomedical devices and implants are adversely affected by biofilm-associated infections that pose serious public health issues. Biosurfactants (BSs) can combat pathogenic biofilms through their antimicrobial, antibiofilm and antiadhesive capabilities. The objective of our research was to produce biosurfactant (BS) from Lactobacillus acidophilus NCIM 2903 and investigate its antibiofilm, antiadhesive potential using microfluidics strategies by mimicking the micro-environment of biofilm. Methods: Antibiofilm and antiadhesive potential was effectively evaluated using different methods like microfluidics assay, catheter assay, polydimethlysiloxane (PDMS) disc assay. Along with this chemical and physical characteristics of BS were also evaluated. Results: Cell free biosurfactant (CFBS) obtained was found to be effective against biofilm which was validated through the microfluidic (MF) or Lab on Chip (LOC) approach. The potency of CFBS was also evaluated on catheter tubing and PDMS surfaces (representative bioimplants). The efficacy of CFBS was also demonstrated through the reduction in surface tension, interfacial tension, contact angle and low critical micelle concentration. Conclusion: CFBS was found to be a potent antimicrobial and antibiofilm agent. We believe that perhaps this is the first report on demonstrating the inhibiting effect of Lactobacillus spp. derived CFBS against selected bacteria via LOC approach. These findings can be explored to design various BSs based formulations exhibiting antimicrobial, antibiofilm and antiadhesive potential for biomedical applications.

A novel solution to reduce the complications of distal shunt catheter displacement associated with obesity

Despite the varied sources of hydrocephalus, all shunt-treated conditions involve redirection of CSF to the body, commonly the peritoneum. Migration of the distal catheter tip out of the peritoneal space can occur, leading to the need for reoperation. Although uncommon, the authors have recently had 3 such cases in obese patients involving distal tubing retropulsion in otherwise uncomplicated surgeries. In addressing this issue, the authors performed anchoring of the distal catheter tubing through a small abdominal mesh, which is commonly used for hernia repair to increase catheter tube friction without compromising CSF flow. The results suggest this method may mitigate the chance of peritoneal catheter displacement in patients with higher than normal intraabdominal pressure.