Off-Chip-Controlled Droplet-on-Demand Method for Precise Sample Handling.

We present a simple, stable, and highly reproducible off-chip-controlled method for generating droplets-on-demand. To induce the droplet generation, externally pre-programmed positive pressure pulses are applied to the dispersed phase input while the continuous phase channel remains at constant input pressure. By controlling solely one fluid phase, the method allows for connecting multiple independent dispersed-phase channels to a single continuous channel. Experimental results show that the method allows for a droplet generation frequency of 33 Hz and a high reproducibility of droplets with standard deviations less than 5% of the mean value. Moreover, utilization of the off-chip-controlled method results in the simplicity in chip design and allows rapid (∼5 min) and cost-efficient (0.5 USD) prototyping of the device.

Glomerular filtration rate in examined population of Bosnian Posavina - region of Balkan Endemic Nephropathy.

Balkan endemic nephropathy (BEN) is chronic tubulointersticial nephritis of unknown aetiology characterized by an insidious onset and gradual progression to end stage renal disease (ESRD). Endemic regions of Bosnia and Herzegovina are Posavina and Semberija, sited at basin of Sava River. In BEN, just like in other chronic renal diseases (CKD), glomerular filtration rate (GFR), is assumed a marker of overall renal function. The aim of this study was to compare GFR in examinees of endemic and non-endemic region for BEN, and between examinees with and without risk factors for BEN within endemic region. Study included 603 inhabitants of Bosnian Posavina, out of whom 386 (65%) from endemic (Domaljevac) and 217 (36%) from non-endemic (Svilaj) village, and it was performed in two phases. The first phase encompassed obtaining anamnestic data (demographic, personal and family history), measurement of arterial blood pressure, and urine dipstick testing (specific gravity, pH, proteins, leukocytes, glucose, ketones, and microalbuminuria). In the second phase, besides repeated urine dipstick test, laboratory blood testing and abdominal ultrasound, with special attention to urinary tract, was also performed. We have compared GFR between examinees of endemic and non-endemic regions for BEN, and between examinees with and without family burden for BEN within endemic region, using MDRD formula for calculating GFR, with cut-off value (5th percentile) based on result of studies performed in European Caucasians in screening for CKD and for establishing stages of CKD in BEN. Medical was used for statistical testing. Out of total number of examined inhabitants (603), 145 examinees were included in the second phase. After exclusion of 17 diabetic patients, 94 (73%) examinees from endemic and 34 (27%) examinees from non-endemic region remained. In the endemic region there were 46 (49%) examinees with and 48 (51%) without family burden for BEN. Overall GFR in examined groups was within physiologic range. There was not statistically significant difference in calculated GFR between examinees of endemic and non-endemic regions for BEN (Mann-Whitney test p=0.104; Fisher's test p=1), neither between examinees with and without family burden for BEN within endemic region (Mann-Whitney test p=0,7393; Fisher's test p=0,263). Overall GFR in examined groups was within physiologic range. There wasn't statistically significant difference in calculated GFR between examinees of endemic and non-endemic regions for BEN, neither between examinees with and without family burden for BEN within endemic region. GFR, no matter how accurately calculated and estimated, does not represent significant biomarker for diagnosis, especially early diagnosis, of BEN, until maybe its overt advanced form.