Influence of nanostructural environment and fluid flow on osteoblast-like cell behavior: a model for cell-mechanics studies.

Introducing nanoroughness on various biomaterials has been shown to profoundly effect cell-material interactions. Similarly, physical forces act on a diverse array of cells and tissues. Particularly in bone, the tissue experiences compressive or tensile forces resulting in fluid shear stress. The current study aimed to develop an experimental setup for bone cell behavior, combining a nanometrically grooved substrate (200 nm wide, 50 nm deep) mimicking the collagen fibrils of the extracellular matrix, with mechanical stimulation by pulsatile fluid flow (PFF). MC3T3-E1 osteoblast-like cells were assessed for morphology, expression of genes involved in cell attachment and osteoblastogenesis and nitric oxide (NO) release. The results showed that both nanotexture and PFF did affect cellular morphology. Cells aligned on nanotexture substrate in a direction parallel to the groove orientation. PFF at a magnitude of 0.7 Pa was sufficient to induce alignment of cells on a smooth surface in a direction perpendicular to the applied flow. When environmental cues texture and flow were interacting, PFF of 1.4 Pa applied parallel to the nanogrooves initiated significant cellular realignment. PFF increased NO synthesis 15-fold in cells attached to both smooth and nanotextured substrates. Increased collagen and alkaline phosphatase mRNA expression was observed on the nanotextured substrate, but not on the smooth substrate. Furthermore, vinculin and bone sialoprotein were up-regulated after 1 h of PFF stimulation. In conclusion, the data show that interstitial fluid forces and structural cues mimicking extracellular matrix contribute to the final bone cell morphology and behavior, which might have potential application in tissue engineering.

[Recurrent ulcers in the Zollinger-Ellison syndrome]. / Recidivantni ulkusi na bazi Zollinger-Ellisonovog sindroma.

Authors present a case of recurrent duodenal ulcer on the basis of Zollinger-Ellison syndrome. After two operations: vagotomy and gastric resection, it appear a gastrojejunocolic fistula produced by marginal ulceration following gastroenterostomy. Zollinger-Ellison syndrome is proved with echotomography of pancreas, examinations of gastrin, whose levels was high, as well as with examination of gastric secretion and biopsy of gastric mucosa. A total gastrectomy is performed as the safest surgical procedure, because all other operative treatments as vagotomy and resection's methods are of no help. Patient has recovered quickly after the operation with substitutional therapy. There was no more oedema, diarrhea, and he has recovered his working quality.

[Cysts of the choledochus. Report of a case]. / Ciste duktusa choledochusa. Povodom jednog naseg slucaja

Cysts of the common bile duct, (also known as common bile coeles, or as common bile cysts) are quite rare. Those of the ampulla of Vater are a curious phenomena. Cysts of the extrahepatic part of the common bile duct can be quite large, excentrically located, and produce a triad of symptoms: pain, tumor and jaundice. These symptoms are intermittent, however, due to the periodic emptying of the cysts' contents into the duodenum. Cysts of the ampulla of Vater are those which occur in the intraduodenal part of the bile duct, and almost always found projecting into the lumen of the duodenum--imitating a tumor as it was in our case. Preoperative diagnosis of these cysts is extremely difficult, especially if the cyst is situated on the ampullar part of the common bile duct, and they are usually discovered during the operation. Possible compression of the ampulla of Vater, and the pancreatic duct can result in recidivating pancreatitis. The operative approach is dependent on the size of the cyst, and its location. The best is the complete removal of the cyst, and a correction of bile flow.