Misc

As oral or intestinal bacteria have been found in pancreatic cystic fluid and tumors, understanding bacterial migration from the duodenum into the pancreas via hepato-pancreatic duct is critical. Mathematical models of migration of aerobic bacteria from the duodenum to the pancreas with tumors were developed. Additionally, the bacterial distributions under the pH gradient and those under flow were measured in double-layer flow based microfluidic device and T-shaped cylinders. Migration of aerobic bacteria from the duodenum into pancreas is counteracted by bile and pancreatic juice flow but facilitated by pH-taxis from acidic duodenum fluid toward more favorable slightly alkaline pH in pancreatic juice. Additionally, the reduced flow velocity in cancer patients, due to compressed pancreatic duct by solid tumor, facilitates migration. Moreover, measured distribution of GFP E. coli under the pH gradient in a microfluidic device validated pH-tactic behaviors. Furthermore, Pseudomonas fluorescens in hydrochloride solution, but not in bicarbonate solution, migrated upstream against bicarbonate flow of > 20 μm/s, with an advancement at approximately 50 μm/s.

Mechanical properties of erythrocytes under diabetic and some other physico-chemical conditions were measured by using transparent micro-channel flow system for the analysis of erythrocyte deformability and also by using atomic force microscope (AFM) for the analysis of microscopic elasticity of the erythrocyte cell membrane respectively. Deformability of diabetic erythrocytes was significantly lower than that of healthy controls, especially at higher shear rate. The spring constant and the Young's modulus of diabetic erythrocytes were much higher than those of healthy controls. These erythrocytes were obviously stiffened to be hard to deform themselves in the capillary flow passage that may follow to the growth of microangiopathy.