The tomato cv. Fukuju nº. 2 was used for studying the effect of single and double infections with Potato virus X (PVX) and Tobacco mosaic virus (TMV). Mixed infection resulted in a synergistic increase of disease severity, where more growth reduction was seen with simultaneous inoculations than with sequential inoculations at four-day intervals. At five and 12 days post-inoculation, the increased severity of the disease coincided with enhancement of virus accumulation in the rapidly expanding upper leaves. The PVX concentration in leaves nº 5 to 7 of doubly infected plants was three to six fold that of singly infected ones, as determined by DAS-ELISA. Mixed infection with the L strain led to higher enhancement of PVX than with the TMV-L11A strain. The concentration of TMV-L was lower in double infection and significantly higher than TMV-L11A in both singly and doubly infected plants. Analyses of the PVX ORF2 by Western blot and Northern hybridization revealed the pattern of accumulation of the 25 kDa protein and the RNAs, respectively, following those of the virion and coat protein. The strain TMV-L11A overcame the resistance gene in cv. GCR 237 (Tm-1). In the upper leaf nº. 8, the concentration of PVX was three times higher in plants with mixed infection than with L11A. The concentrations of the L and OM (TMV strains) in both singly and doubly infected plants were at very low levels, and the synergistic effect on PVX concentration and disease severity was not observed.

For avascular necrosis of the femoral head (ANFH), repair and regeneration are difficult because of the edema and high pressure caused by continuous ischemia and hypoxia. Core decompression (CD) is a classic method for treating early ANFH before the collapse of the femoral head; however, its effect is still controversial. To improve the therapeutic effect of CD on ANFH, a novel tissue-engineered bone (TEB) was constructed by combining bone marrow mesenchymal stem cells (BMSCs) with nano-hydroxyapatite/collagen I/poly-L-lactic acid (nHAC/PLA) scaffolds and implanting the TEB into the bone tunnel of CD. Cell attachment was observed by scanning electron microscopy and hematoxylin and eosin staining. The authors' previous studies confirmed that nHAC/PLA is an excellent scaffold material with favorable biocompatibility and no cytotoxicity. A total of 24 New Zealand rabbits with ANFH were randomly divided into three groups, as follows: Group A (n=8), pure CD; group B (n=8), CD+nHAC/PLA; and group C (n=8), CD+BMSCs-nHAC/PLA. The favorable effect of BMSCs-nHAC/PLA on angiogenesis and bone formation in necrotic areas was further evaluated via radiographic and histological analyses. Computerized tomography (CT) scanning and H&E staining showed more capillaries and new osteoid tissue in group C compared with in groups B and A. Micro-CT showed that the new bone coverage rate and implanted material degradation degree were each increased in group C compared with in group B. These results indicate that BMSCs-nHAC/PLA scaffolds may improve the curative effect of CD and provide a strategy for treating ANFH.

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