Expression of <Emphasis Type="Italic">Ruminococcus albus</Emphasis> Xylanase Gene (<Emphasis Type="Italic">xyn</Emphasis>A) in <Emphasis Type="Italic">Streptococcus bovis</Emphasis> 12-U-1

The objective of this study was to ligate the xylanase gene A (xynA) isolated from Ruminococcus albus 7 into the promoter and signal-peptide region of the lichenase [β-(1,3-1,4)-glucanase] gene of Streptococcus bovis JB1. This fusion gene was inserted into the pSBE11 vector, and the resulting recombinant, plasmid pXA, was used to transform S. bovis 12-U-1 cells. The transformant, S. bovis 12UXA, secreted the xylanase, which was stable against freeze-thaw treatment and long-time incubation at 37°C. The introduction of pXA and production of xylanase did not affect cell growth, and the xylanase produced degraded xylan from oat-spelt and birchwood. Received: 24 June 2002 / Accepted: 7 October 2002     

Effect of hip joint angle at seat-off on hip joint contact force during sit-to-stand movement: a computer simulation study

Background

Sit-to-stand movements are a necessary part of daily life, and excessive mechanical stress on the articular cartilage has been reported to encourage the progression of osteoarthritis. Although a change in hip joint angle at seat-off may affect hip joint contact force during a sit-to-stand movement, the effect is unclear. This study aimed to examine the effect of the hip joint angle at seat-off on the hip joint contact force during a sit-to-stand movement by using a computer simulation.

Methods

A musculoskeletal model was created for the computer simulation, and eight muscles were attached to each lower limb. Various sit-to-stand movements were generated using parameters (e.g., seat height and time from seat-off to standing posture) reported by previous studies. The hip joint contact force for each sit-to-stand movement was calculated. Furthermore, the effect of the hip joint angle at seat-off on the hip joint contact force during the sit-to-stand movement was examined. In this study, as the changes to the musculoskeletal model parameters affect the hip joint contact force, a sensitivity analysis was conducted.

Results and conclusions

The hip joint contact force during the sit-to-stand movement increased approximately linearly as the hip flexion angle at the seat-off increased. Moreover, the normal sit-to-stand movement and the sit-to-stand movement yielding a minimum hip joint contact force were approximately equivalent. The effect of the changes to the musculoskeletal model parameters on the main findings of this study was minimal. Thus, the main findings are robust and may help prevent the progression of hip osteoarthritis by decreasing mechanical stress, which will be explored in future studies.

     

Uptake of nitrogen and production of kainic acid by laboratory culture of the red alga Digenea simplex

The red alga Digenea simplex was cultured with various culture media to clarify the nutritional conditions to produce kainic acid (KA ). Unlike the domoic acid‐producing red alga Chondria armata , D. simplex was insensitive to excessive manganese, and grew best (mean growth rate approximately 800% for 25 days) in modified PES medium (mPES ; seawater + nitrate, phosphate, iron, trace metals, vitamins, and 2‐[4‐(2‐hydroxyethyl)‐1‐piperazinyl]‐ ethanesulfonic acid) prepared with autoclaved seawater. Liquid chromatography‐mass spectrometry analysis of the algal extracts revealed that the KA content of the explants cultured with mPES or N·P·Fe medium (seawater + nitrate, phosphate, and iron) was somewhat higher than that of wild specimens (1748–2378 μg g^?1 vs 1562 μg g^?1). The ¹H‐nuclear magnetic resonance spectrum of the KA extracted and purified from pooled explants was indistinguishable from the previously reported KA spectrum. When D. simplex was cultured for 6 weeks with medium in which NaNO ₃ of mPES was replaced by Na¹⁵NO ₃, the ratio of ²¹⁴KA to total measured KA (^totalKA = ²¹³KA + ²¹⁴KA ) in the cultured explants (0.1 at the beginning of culture) gradually increased to 2.5, indicating that D. simplex produces KA in proportion to its growth under the condition in which sufficient nitrogen source is available.     

Quantitative and metabolic changes of hepatic collagens in rats after carbon tetrachloride poisoning

1. The collagen hydroxyproline in rat liver was composed of 3.5% neutral-soluble collagen, 4.9% acid-soluble collagen and 91.6% insoluble collagen. In labelling studies with [(14)C]proline in vitro, the specific radioactivities of neutral-soluble, acid-soluble and insoluble collagens in rat liver were found to be 233000, 69000 and 830d.p.m./mumol of hydroxyproline respectively after 1h. 2. During subacute carbon tetrachloride poisoning the hepatic content of insoluble collagen markedly increased, whereas those of soluble collagens did not change. During recovery from subacute poisoning hepatic contents of soluble collagens were markedly decreased. 3. After 8 weeks of carbon tetrachloride poisoning the specific radioactivities of hepatic soluble collagens increased, while that of insoluble collagen decreased. During recovery from subacute poisoning, the specific radioactivities of soluble collagens decreased to the normal range and that of insoluble collagen further decreased. 4. Hepatic collagenolytic activity solubilizing insoluble collagen, which differs from mammalian collagenase, decreased under the conditions of the subacute poisoning and also during recovery from subacute poisoning.     

Primary pulmonary malignant peripheral nerve sheath tumor: a case report

BACKGROUND: Although the histologic features of malignant peripheral nerve sheath tumor (MPNST) have been described, the cytologic features of primary pulmonary MPNST have not been reported in the literature. CASE: We report a case of primary pulmonary MPNST in a 78-year-old man. Follow-up computed tomography of colon cancer, renal cancer, penile cancer and gingival cancer revealed a nodular lesion, 12 mm in diameter, in the right upper lobe of the lung. In frozen section, a diagnosis of malignant neoplasm, not otherwise specified, was rendered for the imprinting specimen and histologic specimen. Imprinting specimens were composed of small cellular aggregates and discohesive neoplastic cells with obvious malignant features. Histologically, spindle cells with pleomorphic nuclei arranged infascicular patterns and multinucleated tumor giant cells were also observed. More than 25 mitotic figures were observed per 10 high-power fields. Tumor cells were positive only for vimentin and S-100, and the Ki-67 labeling index was 10%. Clinical and imaging investigation failed to identify an alternative primary site. We histologically diagnosed this case as primary pulmonary MPNST. CONCLUSION: MPNST has a varied cytomorphology with frank nuclear atypia showing no definite differentiation. Multinucleated neoplastic giant cells with immunopositivity for S-100 may permit more accurate diagnosis of MPNST.     

VEGF contributes to postnatal neovascularization by mobilizing bone marrow-derived endothelial progenitor cells.

Vascular endothelial growth factor (VEGF) has been shown to promote neovascularization in animal models and, more recently, in human subjects. This feature has been assumed to result exclusively from its direct effects on fully differentiated endothelial cells, i.e. angiogenesis. Given its regulatory role in both angiogenesis and vasculogenesis during fetal development, we investigated the hypothesis that VEGF may modulate endothelial progenitor cell (EPC) kinetics for postnatal neovascularization. Indeed, we observed an increase in circulating EPCs following VEGF administration in vivo. VEGF-induced mobilization of bone marrow-derived EPCs resulted in increased differentiated EPCs in vitro and augmented corneal neovascularization in vivo. These findings thus establish a novel role for VEGF in postnatal neovascularization which complements its known impact on angiogenesis.     

Freeze-fracture electron microscopic study of tight junction strands in HEK293 cells and MDCK II cells expressing claudin-1 mutants in the second extracellular loop

Claudins constitute tight junction (TJ) strands. In order to examine the function of the second extracellular loop (ECL2), we constructed 1CLΔFY and 1CLΔPL in which highly conserved amino acids, FY or PL, in the ECL2 of mouse claudin-1 were deleted. They were then tagged with either EGFP at the NH₂-terminus (EGFP1CLΔFY and EGFP1CLΔPL) or the myc-epitope at the COOH-terminus (1CLΔFYmyc and 1CLΔPLmyc). The expression of EGFP1CLΔFY and EGFP1CLΔPL in TJ-free HEK293 cells formed TJ strands resembling those formed by wild-type claudin-1. The expression of 1CLΔPLmyc in TJ-bearing MDCK II cells induced aberrant TJ strands in the lateral plasma membranes whose intramembranous particles were almost equally distributed in the P- and E-face. In contrast, 1CLΔFYmyc formed aggregates of short continuous strands which were frequently associated with vesicle-like structures. Coculture experiments with MDCK II cells showed that 1CLΔPLmyc was localized at heterotypic cell–cell junctions but 1CLΔFYmyc was not. These results suggest that changes in the TJ morphology due to the expression of either 1CLΔFYmyc or 1CLΔPLmyc may be caused by some factors specific to epithelial MDCK II cells including endogenous claudins. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.