Failure of adefovir 20 mg to improve suboptimal response in lamivudine-resistant hepatitis B patients treated with adefovir 10 mg and lamivudine.

Nine patients with lamivudine-resistant chronic hepatitis B infection who had been treated with adefovir 10 mg/day and had had a suboptimal response but did not have genotypic resistance to adefovir were treated with high-dose adefovir (20 mg/day). The response to the increased dose of adefovir was compared with the response in 15 patients with a suboptimal response who did not receive an increase in the dose of adefovir. The increase in the dose of adefovir did not lead to a significant reduction in hepatitis B DNA when compared with patients maintained on the standard dose. These data suggest that increasing the dose of adefovir in patients with a suboptimal response does not lead to an improved response.

Mesenchymal stem cells cultured on a collagen scaffold: In vitro osteogenic differentiation.

OBJECTIVE: Management of periodontal defects has always been a challenge in clinical periodontics. Recently mesenchymal stem cells (MSC) have been proposed for tissue regeneration in periodontal disease and repair of large bone defects. Bone regeneration has to be supported by a scaffold which has to be biocompatible, biodegradable, and able to support cell growth and differentiation. The aim of this study was to evaluate osteogenic differentiation of MSC seeded on a collagen scaffold. DESIGN: MSC were obtained from adult rat bone marrow, expanded and cultured in plastic dishes or seeded in a collagen scaffold (Gingistat). MSC were induced towards osteogenic differentiation using osteogenic supplements. Cell differentiation and calcium deposits were evaluated by immunoblotting, immunohistochemistry, histochemical techniques, enzymatic activity assay, and SEM-EDX analysis. Biomaterial in vitro degradation was evaluated by measuring mass reduction after incubation in culture medium. RESULTS: Rat MSC osteogenic differentiation was demonstrated by osteopontin and osteocalcin expression and an increase in alkaline phosphatase activity. MSC were distributed homogeneously in the collagen scaffold. Nodular aggregates and alizarin red stained calcium deposits were observed in MSC induced towards osteogenic differentiation cultured in dishes or seeded in the collagen scaffold. SEM-EDX analysis demonstrated that calcium co-localized with phosphorous. The biomaterial in vitro degraded in 4-5 weeks. CONCLUSIONS: MSC from bone marrow differentiate towards osteogenic lineage, representing a suitable cell source for bone formation in periodontal regeneration. Gingistat collagen scaffold supports MSC distribution and differentiation, but its short degradation time may be a limitation for a future application in bone tissue regeneration.

Effectiveness of leukocyte filters in reducing tumor cell contamination after intraoperative blood salvage in lung cancer patients.

OBJECTIVES: In an effort to reduce allogeneic blood transfusions in patients undergoing elective surgery for lung cancer, we investigated the effectiveness of a method of processing shed blood with an automated device for intra operative blood salvage (IOBS) and filtration with a 3rd-generation polyester filter to remove tumor cells. METHODS: Sixteen patients were operated on for different types of lung cancer. We searched for malignant cells in pre- and postprocessed shed blood employing density gradient centrifugation, staining of cytospins with hematoxylin-eosin, and antibodies to human cytokeratins. RESULTS: In 9 out of 16 cases (56%), neoplastic cells were detected in prefiltration samples, but none were found in postfiltration cytospins. CONCLUSION: IOBS combined with appropriate filtration could be a very useful and safe tool in reducing allogeneic blood transfusion in cancer patients.

Hemodialysis using a constant potassium gradient: rationale of a multicenter study.

The aim of this study is to evaluate the relationship between two different procedures for potassium removal during hemodialysis (HD) and cardiac arrhythmias. Cell excitability and the transmission of impulses may be influenced by variations of resting membrane potential (RMP). The rapid decrease of plasma potassium during the first two hours of standard HD causes a membrane hyperpolarization. A different K+ kinetic, with a gradual and constant elimination of K+ during HD, may reduce this further unphysiological aspect and its clinical consequences. This can be obtained keeping blood-dialysate K+ gradient as constant as possible with the use of a dialysate K+ concentration (Kd) decreasing during HD. Our experimental studies on various K+ intradialytic gradients seem to indicate as optimal to this purpose K+ gradients of 1.5 mEq/l at the beginning of dialysis, esponentially decreasing during treatment to Kd values of 2.5 mEq/l at the end of dialysis (variable Kd). Patients included in the trial will be submitted to two different methods of treatment with Kd 2 mEq/l and variable Kd, and to a 24 hours ECG the day of dialysis. We will compare the number of intra and interdialytic premature ventricular complexes to evaluate the impact of two different models of potassium removal on arrhythmias.