A novel two-step method for the formation of tissue-engineered cartilage by mature bovine chondrocytes: the alginate-recovered-chondrocyte (ARC) method.

Most attempts to tissue-engineer cartilage have involved seeding of cultured cells into a biological or synthetic scaffold. We have developed a novel two-step culture approach that makes possible the in vitro formation of cartilaginous-like tissue by mature adult bovine chondrocytes without the aid of a synthetic matrix. The first step consists of culturing chondrocytes under conditions that maintain their rounded shape and their molecular phenotype as assessed by type II collagen and aggrecan production. This step was accomplished by culturing the isolated chondrocytes in alginate beads until the cells have reestablished a proteoglycan-rich cell-associated matrix (CM). The second step consists of culturing the cells with their CM, after recovery from the beads, on a tissue culture insert with a porous membrane. In this study, young adult bovine articular chondrocytes were cultured in alginate beads in the presence of 10% or 20% fetal bovine serum (FBS). After 7 days of culture, the alginate beads were dissolved by incubating the beads for 20 min in sodium citrate buffer, a calcium chelator. Following a brief centrifugation, the cells with their CM were recovered, resuspended in medium containing 10% or 20% FBS and seeded onto a tissue culture insert. After 1 week of culture on the insert, the individual cells with their CM progressively became incorporated into a mass of cartilaginous tissue. Culture with 20% FBS resulted in the best formation of tissues. These tissues, easily recovered from the insert, were then subjected to biochemical and histological analyses. The biochemical results showed that the chondrocytes remain phenotypically stable in the tissues. The de novo tissue has a relatively high ratio of PG/collagen. Histological examination of the tissue revealed it contained a cartilage-like matrix strongly stained with toluidine blue. This scaffold-free system appears ideal to study, in vitro, the development of transplantable cartilaginous tissue.     

The effect of teacher reaction on student's interactive journal entries

The present study provides an analysis of the effects of particular patterns of teacher respose to students' entries in dialogue journals. It extended on previous research related to teacher-student instructional discourse by concentrating on written, teacher-student interactions. Second grade children who were participating in a daily dialogue journal activity were randomly subjected to two types of response patterns by their teacher. The results show that a teacher's elaborative responses to student journal entries directly lead to increase written output by students coupled with a distinct process #ophigher order#cp orientation of student entries.     

Cytologic findings in stage I adenocarcinoma of the lung: Implications for the detection of early lung cancer

Preoperative cytologic examinations were performed on bronchial material from 92 patients with postsurgical (pathologic) stage I (American Joint Committee) adenocarcinoma of the lung. All patients were followed up for at least 5 years or until death; thus, cases of adenocarcinoma metastatic to the lungs were virtually excluded. Only 22 patients (24%) had abnormal preoperative cytologic findings. This low cytologic sensitivity is ascribed to the small size and peripheral location of the tumors. Large lesions of high histologic grades were more likely to have positive preoperative cytologic findings than small, well-differentiated ones.     

Kidney retrieval conditions influence damage to renal medulla: evaluation by proton nuclear magnetic resonance (NMR) pectroscopy.

In the present investigation, the influence of retrieval condition on medullary damage in kidneys was assessed. The isolated perfused pig kidney was used to assess initial renal function from multiorgan donors or single organ donors after cold flush and 24 h cold storage preservation with two preservation solutions: Euro-Collins and University of Wisconsin solutions. Kidneys flushed with cold heparinized saline and immediately perfused were used as a control group. Kidneys were perfused for 90 min at 37.5 degrees C and renal perfusion flow rate, glomerular filtration rate, tubular reabsorption of Na+ and lactate dehydrogenase and N-acetyl-beta-D-glucosaminidase excretion were determined. Ischaemia reperfusion impairment was also determined by 1H NMR (proton nuclear magnetic resonance) spectroscopy. Renal function was significantly decreased in experimental groups when compared to the control group, but there was no significant difference between experimental groups after 24 h cold storage. The release of lactate dehydrogenase in the effluent and the urinary excretion of N-acetyl-beta-D-glucosaminidase were not significantly different after 24 h cold storage. The most relevant resonances determined by 1H NMR spectroscopy were citrate, trimethylamine-N-oxide, lactate, acetate and amino acids. Excretion of these markers was significantly different when compared to biochemical markers. A resonance P (Peak) detected particularly in Euro-Collins solution multiorgan donors after 24 h cold storage was identified and well correlated to renal dysfunction. N-acetyl-beta-D-glucosaminidase spectroscopy, which is a non-invasive and non-destructive technique, is more efficient to assess renal damage than conventional histology and biochemical analysis.