Renal tubular epithelial cells express osteonectin in vivo and in vitro.

Osteonectin (SPARC, culture shock protein, BM-40) is a widely distributed glycoprotein which binds calcium and several extracellular matrix proteins, including interstitial collagens and thrombospondin, but whose physiologic role remains undefined. In the present studies, we have demonstrated that immunoreactive osteonectin is present in the distal cortical tubule and medullary tubules of murine kidney. We surveyed the renal epithelial cell lines LLC-PK1, MDCK, and OK for the expression of mRNA encoding osteonectin. We found that osteonectin mRNA is expressed by LLC-PK1 and OK cells but not by MDCK cells, as well as by adult kidney from several species. Calcitonin and vasopressin, agents which increase cAMP in these cells, were found to decrease steady-state osteonectin mRNA concentrations. We found that LLC-PK1 cells produced osteonectin protein, that the protein was localized to intracellular granules, and that the protein bound hydroxyapatite in vitro. Pulse-chase analysis revealed that osteonectin was secreted from the cell layer to the medium after a lag time of four to six hours and was secreted preferentially from the basolateral domain of the cell. The preferential secretion of the calcium-binding protein osteonectin from the renal epithelial cell is consistent with several possible functions, including a structural extracellular matrix protein, a participant in transepithelial ion transport, and an inhibitor of extracellular calcification.     

Laparoscopic nephrectomy in a porcine model.

Laparoscopic nephrectomy was performed in 15 male pigs, the procedure was successful in 14. Extraction of the intact kidney through a 5-cm lower abdomen incision was done in 7 animals; complete destruction and evacuation of the kidney was accomplished by a round-knife suction device through a 1-cm port in another 7 pigs. Grossly, the specimen consisted of sausage-like tubular renal tissue and a small amount of tissue debris. Pathology revealed that the glomerular and tubular structures were well preserved, no interstitial hematoma could be found. Four ports were usually used, one 1-cm umbilical camera port, one 0.5-cm port for ureter traction, and two 1-cm working ports along the midclavicular line. All the pigs recovered uneventfully. The average operation time was 3 h 20 min. The application of endo-GIA (United States Surgical Corporation) for renal hilum reduced the operative time to 2 h 20 min. Complications included renal vein tear during endoclip application and cutting in the first case, mild subcutaneous emphysema in 2 cases. This first pig received exploratory laparotomy for the repair and ligation of the renal vein. No more major complications occurred with increasing experience. From this porcine experiment, we conclude that the combination of laparoscopy, a tissue destroyer and an endobag for the entrapment of kidney seem to be a promising technique for clinical nephrectomy.     

Percutaneous bone marrow grafting of fractures and bony defects. An experimental study in rabbits

Since bone marrow has been shown to contain osteoprogenitor cells, an experiment was devised to test its effects when injected percutaneously into osteotomies and 2-cm bony defects produced in rabbit radii. The parameters tested included callus volume, breaking load, tensile strength, and cross-sectional area of callus at the fracture or bony defect site. At two weeks postgrafting callus volume was significantly higher (p less than 0.01) in the grafted radii than in the contralateral saline controls. By four weeks all four parameters were significantly greater in the bone marrow grafted radii than in the contralateral saline controls. Serial radiographs and histology confirm this advanced fracture healing in the grafted bones. The earlier and more abundant callus, at the bone marrow grafted sites, was felt to provide earlier and greater stability, resulting in decreased early healing time when contrasted with the saline controls. Similarly, the bony defects that were grafted with bone marrow united by a bony bridge, whereas the saline controls did not. Percutaneous bone marrow grafting is a simple semi-invasive technique that may have potential clinical applications.     

Case-control study of colon cancer and drinking water trihalomethanes in Wisconsin

A case-control study was conducted to test the hypothesis that chronic ingestion of trihalomethanes (THMs), occurring as chlorination byproducts in drinking water, carries a risk of colon cancer. Lifetime residential and water source histories and information on water-drinking habits, diet, sociodemographics, medical and occupation histories, lifestyle and other factors were obtained by questionnaire from a statewide sample of newly-diagnosed colon cancer cases (N = 347), controls with cancer of other sites (N = 639) and general population controls (N = 611). Since no data on past THM levels exists, it was necessary to devise a scheme to generate THM estimates for all Wisconsin water sources. For this, a statistical model based on quantitative THM measures and routinely-recorded data taken at 81 municipal water facilities was used in conjunction with individual residential histories to estimate lifetime and period-specific THM exposure for each case and control. Logistic regression was used to estimate odds ratios adjusted for age, sex and urban living, for colon cancer and THM exposure. The study results indicate that THM in Wisconsin drinking water does not pose a significant colon cancer risk. Odds ratios for exposure to the middle and highest category of lifetime cumulative THM were 1.05 (95% Cl = 0.66-1.68) and 0.93(95%Cl = 0.55-1.57) respectively, relative to the cancer control group, and 1.10 (95%Cl = 0.68-1.78) and 0.73 (95% Cl = 0.44-1.21) respectively, relative to the general population controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Experimental transmission of Plasmodium mexicanum by bites of infected Lutzomyia vexator (Diptera: Psychodidae)

Lutzomyia vexator is an efficient experimental vector of Plasmodium mexicanum, infecting 69.2% (9/13) of the Sceloporus undulatus lizards with as few as one bite. Sporozoites were present in the salivary glands by day 6.5 postfeed and infective by day 8 postfeed at 27 degrees C. The prepatent period was relatively long, ranging from 23 to 40 days for bite-induced infections and appears to be related to the number of sporozoites injected. The acute phase of the infection is initially exponential and rapid. All lizards (6) that were not sacrificed, died of fulminating infections from 13 to 56 days after parasites were seen in the blood films. Gametocytes from 2 experimentally infected lizards were infective to L. vexator during the course of the acute infection. The majority of P. mexicanum parasites were in erythrocytes of Sc. undulatus. Exoerythrocytic forms were observed in circulating lymphocytes and thrombocytes, lymphocytes of spleen and bone marrow, and endothelial cells of brain capillaries.