[Effects of different disturbance patterns on stand structure of infected pure Pinus massoniana plantation]. / 不同干扰模式对受害马尾松人工纯林林分结构的影响.

To explore the effects of different disturbance patterns on restoring the health of an infected stand, concentrated disturbance of not cutting trees before 10 years after infection, mode-rate disturbance of cutting infected pine trees, and strong distrubance of cutting infected pine trees, the neighboring trees and poorly growing pine trees were compared in a pure Pinus massomiana plantation infected by Bursaphelenchus xylophlius in Anji, Zhejiang, China. After 16 years, the importance values of P. massoniana in the three treatments were: concentrated disturbance > mode-rate disturbance > strong disturbance. However, the importance values of broad-leaved trees showed the opposite trend. Compared with the concentrated disturbance, the average DBH of P. massoniana in the moderate and strong disturbance treatments were 1.2 and 1.7 times higher, respectively, and those of broad-leaved species were 1.3 and 1.9 times higher, respectively. The average height of pine trees in the moderate and strong disturbance treatments increased 1.5 and 2.0 times, respectively, and those of broad-leaved species 1.2 and 1.8 times, respectively. The tree volume per hectare in moderate and strong disturbance treatments were 5.2 and 3.8 times that of concentrated disturbance treatment, respectively. In the moderate and strong disturbance treatments, the number of trees in each diameter class was greater than in the concentrated disturbance treatment. The stand diameter distribution in the multi-storied moderate and strong disturbance treatments followed an inverse J-shaped curve. The species richness and biodiversity were significantly higher in the mode-rate and strong disturbance treatments than in the concentrated disturbance treatment. The individual size inequality and structural complexity indices followed the order of moderate disturbance > strong disturbance > concentrated disturbance. Under moderate and strong disturbance treatments, the single-storied and evenly aged pure P. massoniana plantation became multi-storied and unevenly aged mixed stands. All the three disturbance patterns promoted the succession of broad-leaved trees, with the pace of succession in the order of strong disturbance > moderate disturbance > concentrated disturbance. In conclusion, moderate disturbance achieved better restoration. Thinning pure P. massoniana plantation could accelerate the succession of a mixed stand to enhance resistance against Bursaphelenchus xylophlius invasion.

Rational design of Kluyveromyces marxianus ZJB14056 aldo-keto reductase KmAKR to enhance diastereoselectivity and activity.

t-Butyl 6-cyano-(3R,5R)-dihydroxyhexanoate ((3R,5R)-1b) is a valuable chiral synthon of atorvastatin calcium. A novel NADPH-specific aldo-keto reductase (AKR) was identified from a thermotolerant yeast Kluyveromyces marxianus ZJB14056 by genome database mining, displaying t-butyl 6-cyano-(5R)-hydroxy-3-oxohexanoate ((5R)-1a) reducing activity and moderate diastereoselectivity (dep∼80.5%). Molecular homology modeling and docking studies demonstrated that the side chain of Trp297 blocks binding of (5R)-1a to KmAKR. The mutation of Trp297 to His led to dramatic conformational changes and significant improvement in both diastereoselectivity and activity. In comparison with KmAKR, KmAKR-W297H displayed strict diastereoselectivity, and 2.8-fold, 3.9-fold improvement in kcat and kcat/Km toward (5R)-1a, which were 10.36s-1 and 6.56s-1·mM-1 respectively. Coupling KmAKR-W297H with Exiguobacterium sibiricum glucose dehydrogenase (EsGDH) for coenzyme regeneration, 100mM (5R)-1a was completely reduced to (3R,5R)-1b within 12h, in a dep >99.5%.

An NADPH-dependent Lactobacillus composti short-chain dehydrogenase/reductase: characterization and application to (R)-1-phenylethanol synthesis.

A new anti-Prelog short-chain dehydrogenase/reductase (SDR) encoding gene lcsdr was cloned from Lactobacillus composti DSM 18527, and heterologously expressed in Escherichia coli. LcSDR is nicotinamide adenine dinucleotide phosphate (NADPH)-dependent and has a molecular weight of approximately 30 kDa. The optimal pH and temperature were 6.5 and 30 °C, respectively. The maximal reaction rate Vmax was 133.9 U mg-1; the Michaelis-Menten constant K m of LcSDR were 0.345 mM for acetophenone (1a), and 0.085 mM for NADPH. Through introducing an EsGDH-catalyzed NADPH regeneration system, a biocatalytic process for (R)-1-phenylethanol ((R)-1b) was developed with outstanding time-space yield. Under the optimized conditions, 50 g l-1 1a was converted to (R)-1b in 2 h with a yield of 93.8%, enantiomeric excess of product (e.e.p) above 99% and space-time yield of 562.8 g l-1 d-1.

Effect of early intra-articular injection of alendronate in reducing subchondral bone loss in rat mandibular condyle after ovariectomy / 口腔疾病防治

Objective @#To investigate the effects of intra-articular injection of alendronate on the mandibular condyle in ovariectomized rats.@*Methods @#Sixty female rats were randomly divided into five groups: ovariectomy with vehicle treatment alone, early alendronate treatment at ovariectomy, late alendronate treatment at 4 weeks after ovariectomy, shamoperation with vehicle treatment, and the normal control rats. The changes in subchondral bone were evaluated by micro-computed tomography (Micro-CT), tartrate-resistant acid phosphatase (TRAP) staining and real-time quantitative polymerase chain reaction (RT-PCR). @*Results @# Compared with late alendronate treatment, early alendronate treatment improved microstructural properties of the subchondral bone, with higher bone volume ratio (46.4 + 2.5 vs 37.5 + 2.1; P= 0.038), increased trabecular thickness (47.3 + 1.7 vs 34.6 + 1.4; P = 0.029), elevated trabecular number (8.5 + 0.6 vs 6.2 + 0.3; P = 0.041) and lower trabecular separation (30.2 + 1.6 vs 37.7 + 2.6; P = 0.034). Fewer TRAP-positive cells (4.2 + 0.2 vs 6.8 + 0.4; P = 0.019) and a higher OPG/RANKL ratio (0.38 + 0.01 vs 0.25 + 0.03; P = 0.043) in the subchondral bone were observed in the animals with early treatment group compared to late treatment or ovariectomy/vehicle treatment group. @*Conclusion @#Our results suggest the therapeutic potential of intra-articular alendronate injection in the treatment of osteoporosis-associated temporomandibular disorders.

Growth of the mandible after condylar reconstruction using transport distraction osteogenesis: an experimental investigation in goats.

BACKGROUND: Mandibular condyle damage during childhood disturbs mandibular growth and facial skeletal development. Transport distraction osteogenesis provides a new treatment for condyle reconstruction, but there are no data available on mandibular growth in growing individuals following surgery. The authors investigated the effect of condylar reconstruction by transport distraction osteogenesis on mandibular growth in goats. METHODS: A condylar defect was created unilaterally in 44 growing goats. The animals were divided randomly into group A (n = 22) and group B (n = 22). Transport distraction was used to reconstruct the condyles in group A, whereas group B served as sham controls. Three-dimensional computed tomographic imaging was performed at different intervals. Ten animals from each group were used for mandibular growth measurements at 48 weeks after the end of distraction. Four animals from each group were euthanized at 12, 24, and 48 weeks after surgery. Their transport disks were harvested and processed for histologic evaluation. RESULTS: In group A, the hemimandible of the distracted side exhibited similarities to the contralateral side except for the larger neocondyles. In group B, ramus height and width were significantly shorter on the undistracted side than on the contralateral side; concomitantly, there was mandibular deviation to the operated side. Well-organized fibrocartilage was seen at the neocondylar surface over time in group A but not in group B. CONCLUSIONS: This study suggests that a neocondyle reconstructed by means of transport distraction has the potential to grow under functional stimuli of the temporomandibular joint. Therefore, this technique may serve as an alternative method for condylar reconstruction in growing individuals.

[Study of reconstruction of mandibular condyle by transport distraction osteogenesis in monkeys].

OBJECTIVE: To evaluate the applicability and effectiveness of reconstruction of mandibular condyle by transport distraction osteogenesis in an animal model of rhesus monkeys. METHODS: Six adult rhesus monkeys were used in this study. Bilateral condyles and articular discs were extirpated, and the technique of transport distraction osteogenesis was performed to reconstruct the condyle. X-ray and CT scanning films were taken at various intervals. Two monkeys selected at random were sacrificed respectively at 4, 12 and 24 weeks after completion of distraction, and the newly formed condyles resulted from bony transport disc were harvested and processed for histologic examination. The removed condyles at surgery were used as normal control and prepared in the same manner. RESULTS: Open bite was seen in all animals postoperatively, and disappeared at the end of distraction. The shape and appearance of the bony transport disc was similar to original condyles at sacrifice. The articular cavity was filled with fibrous connective tissue and considerable cartilage cells were observed in the surface of the condyle stump. Bone regeneration was perfect in the distraction gap. CONCLUSION: A neocondyle with functional shape can be created by transport distraction osteogenesis, which suggested that this technique might be an alternative method in reconstruction of the condyle.

[Quantitative histomorphometric observation of distraction osteogenesis during mandibular lengthening].

PURPOSE: To evaluate the regenerating bone during mandibular distraction osteogenesis by bone histomorphometry combining tetracycline bone labeling fluorescence microscopy. METHODS: Osteotomy was performed on bilateral mandibles in ten goats. A custom-made distractor was applied to lengthen the mandible at a rate of 1 mm/d (0.5 mm/12 hrs) for ten days. Every two animals were sacrificed at 10 d, 15 d, 25 d, 35 d and 45 d postoperatively. Two additional goats were used as normal control. The bony specimens were collected and prepared for bone histomorphometry and tetracycline bone labeling fluorescence microscopy with analysis of variance. RESULTS: From 10 days subgroup to 45 days subgroup, bone volume fraction,trabecular thickness,trabecular number and volume density were gradually increased (P<0.05), while trabecular separation distance and surface density were gradually decreased (P<0.05). Between 15 days subgroup and 45 days subgroup,the index of osteoblast was significantly higher than normal control (P<0.05) and index of osteoclast was increased gradually (P<0.05). Compared with normal control, bone formation rate was accelerated by thousand times between 15 days subgroup and 45 days subgroup (P<0.05). CONCLUSIONS: During the process of mandibular distraction osteogenesis, the bone formation is active, the newly formed bone trabecula gradually become mature, and the remodeling activities of regenerated bone are enhanced gradually. The rate of bone formation within distraction period is faster than consolidation period.