Injectable Colloidal Hydrogels of N-Vinylformamide Microgels Dispersed in Covalently Interlinked pH-Responsive Methacrylic Acid-Based Microgels.

Injectable hydrogels offer great potential to augment damaged or degenerated soft tissues. A key criterion for such gels is that their modulus is as close as possible to that of the target tissue. The majority of synthetic hydrogels have used low molecular weight polymer chains which may cause problems if they diffuse away from the injection site and/or increase the local osmotic pressure. We previously introduced a different approach of injecting preformed ultra-high molecular weight pH-responsive microgels (MGs) that interlink to form hydrogels. MGs are crosslinked polymer colloid particles that swell when the pH approaches the particle pKa. These colloidal hydrogels are termed doubly crosslinked microgels (DX MGs). The gel moduli of previous DX MGs were much greater than that reported for human nucleus pulposus (NP) tissue of the spinal intervertebral disk. Here, we replace some of the pH-responsive poly(ethyl acrylate-co-methacrylic acid) (PEA-MAA) MGs with hydrophilic non-ionic MGs based on poly(N-vinylformamide) (NVF). We investigate the morphology and mechanical properties of these new injectable composite DX MGs and show that the mechanical properties can be tuned by systematically varying the NVF MG content. Using this approach, the gel moduli close to that for NP tissue are achieved. These injectable new pH-responsive gels exhibit low cytotoxicity. Our work provides a potential new system for minimally invasive intervertebral disk augmentation.

Liposomal Enzyme Nanoreactors Based on Nanoconfinement for Efficient Antitumor Therapy.

Enzymatic reactions can consume endogenous nutrients of tumors and produce cytotoxic species and are therefore promising tools for treating malignant tumors. Inspired by nature where enzymes are compartmentalized in membranes to achieve high reaction efficiency and separate biological processes with the environment, we develop liposomal nanoreactors that can perform enzymatic cascade reactions in the aqueous nanoconfinement of liposomes. The nanoreactors effectively inhibited tumor growth in vivo by consuming tumor nutrients (glucose and oxygen) and producing highly cytotoxic hydroxyl radicals (⋅OH). Co-compartmentalization of glucose oxidase (GOx) and horseradish peroxidase (HRP) in liposomes could increase local concentration of the intermediate product hydrogen peroxide (H2 O2 ) as well as the acidity due to the generation of gluconic acid by GOx. Both H2 O2 and acidity accelerate the second-step reaction by HRP, hence improving the overall efficiency of the cascade reaction. The biomimetic compartmentalization of enzymatic tandem reactions in biocompatible liposomes provides a promising direction for developing catalytic nanomedicines in antitumor therapy.

A Near-Infrared Light-Activated Photocage Based on a Ruthenium Complex for Cancer Phototherapy.

Conventional photocages only respond to short wavelength light, which is a significant obstacle to developing efficient phototherapy in vivo. The development of photocages activated by near-infrared (NIR) light at wavelengths from 700 to 950 nm is important for in vivo studies but remains challenging. Herein, we describe the synthesis of a photocage based on a ruthenium (Ru) complex with NIR light-triggered photocleavage reaction. The commercial anticancer drug, tetrahydrocurcumin (THC), was coordinated to the RuII center to create the Ru-based photocage that is readily responsive to NIR light at 760 nm. The photocage inherited the anticancer properties of THC. As a proof-of-concept, we further engineered a self-assembled photocage-based nanoparticle system with amphiphilic block copolymers. Upon exposure to NIR light at 760 nm, the Ru complex-based photocages were released from the polymeric nanoparticles and efficiently inhibited tumor proliferation in vivo.

Biodegradable Ru-Containing Polycarbonate Micelles for Photoinduced Anticancer Multitherapeutic Agent Delivery and Phototherapy Enhancement.

The lack of selectivity between tumor and healthy cells, along with inefficient reactive oxygen species production in solid tumors, are two major impediments to the development of anticancer Ru complexes. The development of photoinduced combination therapy based on biodegradable polymers that can be light activated in the "therapeutic window" would be beneficial for enhancing the therapeutic efficacy of Ru complexes. Herein, a biodegradable Ru-containing polymer (poly(DCARu)) is developed, in which two different therapeutics (the drug and the Ru complex) are rationally integrated and then conjugated to a diblock copolymer (MPEG-b-PMCC) containing hydrophilic poly(ethylene glycol) and cyano-functionalized polycarbonate with good degradability and biocompatibility. The polymer self-assembles into micelles with high drug loading capacity, which can be efficiently internalized into tumor cells. Red light induces the generation of singlet oxygen and the release of anticancer drug-Ru complex conjugates from poly(DCARu) micelles, hence inhibiting tumor cell growth. Furthermore, the phototherapy of polymer micelles demonstrates remarkable inhibition of tumor growth in vivo. Meanwhile, polymer micelles exhibit good biocompatibility with blood and healthy tissues, which opens up opportunities for multitherapeutic agent delivery and enhanced phototherapy.

Spatial-temporal heterogeneity of hand, foot and mouth disease and impact of meteorological factors in arid/ semi-arid regions: a case study in Ningxia, China.

BACKGROUND: The incidence of hand, foot and mouth disease (HFMD) varies over space and time and this variability is related to climate and social-economic factors. Majority of studies on HFMD were carried out in humid regions while few have focused on the disease in arid/semi-arid regions, more research in such climates would potentially make the mechanism of HFMD transmission clearer under different climate conditions. METHODS: In this paper, we explore spatial-temporal distribution of HFMD in Ningxia province, which has an arid/semi-arid climate in northwest China. We first employed a Bayesian space-time hierarchy model (BSTHM) to assess the spatial-temporal heterogeneity of the HFMD cases and its relationship with meteorological factors in Ningxia from 2009 to 2013, then used a novel spatial statistical software package GeoDetector to test the spatial-temporal heterogeneity of HFMD risk. RESULTS: The results showed that the spatial relative risks in northern part of Ningxia were higher than those in the south. The highest temporal risk of HFMD incidence was in fall season, with a secondary peak in spring. Meteorological factors, such as average temperature, relative humidity, and wind speed played significant roles in the spatial-temporal distribution of HFMD risk. CONCLUSIONS: The study provide valuable information on HFMD distribution in arid/semi-arid areas in northwest China and facilitate understanding of the concentration of HFMD.

Assessment of condylar morphology and position using MSCT in an Asian population.

OBJECTIVES: The purpose of the present study was to investigate the volume, surface, morphometric index (MI), and position of the condyle in a normal population by applying Mimics 17.0 software. Then, the difference between left and right sides, sex, and age can be explored, which will contribute to establish the reference value of condylar morphology and position in normal individuals, and help us to study characteristics of condylar morphology and position in abnormal individuals. MATERIALS AND METHODS: Three-hundred subjects were enrolled in our study from the radiology department of Shanghai Jiao Tong University Affiliated Sixth People's Hospital. They were divided into three groups according to the age: group 1 (18-24 years old), group 2 (25-34 years old), and group 3 (35-44 years old). Each group included 100 subjects (with 50 males and 50 females). They were examined using multislice computed tomography (MSCT) after that. All images of condyle were reconstructed by Mimics 17.0 software, so as to measure the volume, surface, and MI of condyle, and to analyze the position of condyle in the articular fossa by means of joint spaces. RESULTS: The differences of condylar volume, surface, and MI between left and right sides were not obvious (P > 0.05). The condylar volume and surface were greater in males than females (P < 0.05), while their condylar MI existed no difference (P > 0.05). No statistical differences were found in volume and surface among three age groups. However, the MI of group 1 was statistically lower than that of group 3 (P < 0.05). On the other hand, no significant differences were found between left and right condylar position (P > 0.05). Nevertheless, there were significant differences of condylar position regarding the gender and age (P < 0.05). CONCLUSIONS: This study showed no significant differences in condylar morphology and position between left and right sides, but factors of gender and age were proven to have a certain influence on the morphology and position of the condyle. This information can be clinically useful in establishing the diagnostic criteria for condylar morphology and position in the normal Asian population. CLINICAL RELEVANCE: Examination of condylar morphology and position is important for evaluating the abnormalities and bony changes that affect the temporomandibular joint (TMJ). So, this will be conducive to the diagnosis and the evaluation of therapeutic effect of temporomandibular joint diseases. Also, it is important to evaluate these indexes prior to commencing orthodontic treatment, because TMJ abnormalities play a critical role in orthodontic treatment planning.

IGF-1 C Domain-Modified Hydrogel Enhances Cell Therapy for AKI.

Low cell retention and engraftment after transplantation limit the successful application of stem cell therapy for AKI. Engineered microenvironments consisting of a hydrogel matrix and growth factors have been increasingly successful in controlling stem cell fate by mimicking native stem cell niche components. Here, we synthesized a bioactive hydrogel by immobilizing the C domain peptide of IGF-1 (IGF-1C) on chitosan, and we hypothesized that this hydrogel could provide a favorable niche for adipose-derived mesenchymal stem cells (ADSCs) and thereby enhance cell survival in an AKI model. In vitro studies demonstrated that compared with no hydrogel or chitosan hydrogel only, the chitosan-IGF-1C hydrogel increased cell viability through paracrine effects. In vivo, cotransplantation of the chitosan-IGF-1C hydrogel and ADSCs in ischemic kidneys ameliorated renal function, likely by the observed promotion of stem cell survival and angiogenesis, as visualized by bioluminescence imaging and attenuation of fibrosis. In conclusion, IGF-1C immobilized on a chitosan hydrogel provides an artificial microenvironment for ADSCs and may be a promising therapeutic approach for AKI.

Microplastics exposure causes the senescence of human lung epithelial cells and mouse lungs by inducing ROS signaling.

Microplastics (MPs) are environmental pollutants and can be inhaled by humans to threaten health. The lung tissue, responsible for the gas exchange between the body and the environment, is vulnerable to MPs exposure. However, from the perspective of cellular senescence, the effect of MPs on lung cells and tissues has not yet been deeply dissected. In this study, we reported that all the four typical MPs exhibited the significant biological effects in term of inducing senescence of human lung derived cells A549 and BEAS-2B in vitro. We further found that polyvinyl chloride (PVC) increased the reactive oxygen species (ROS) level in A549 cells and that PVC-induced senescent characteristics could be largely reversed by antioxidant treatment. Importantly, intratracheal instillation of PVC MPs in mice could effectively impair their physical function, induce the increased systemic inflammation level, cause the accumulation of senescent cells. Our study demonstrates that MPs induce senescence in human lung epithelial cells and mouse lungs by activating ROS signaling, and provides new insight into the potential pathogenesis of MPs on lung diseases.

Large Angiomatous Nasal Polyp Presents With Epistaxis Imitating Juvenile Nasopharyngeal Angiofibroma.

An angiomatous nasal polyp is a rare subtype of sinonasal polyp that is commonly found in the middle meatus and characterized by the presence of blood vessels within polyp tissue. It is a benign lesion but is prone to misdiagnosis as a malignant tumor because it typically grows larger and is more vascular than other types of polyps. In this report, a 16-year-old male with no significant past medical history presents with a six-month history of epistaxis and progressive nasal obstruction. Examination of the oral cavity showed a centrally located soft palate mass. CT maxillofacial with contrast showed a hypervascular 3.4 x 4.7 x 6.1 cm mass in the nasal cavity extending through the nasal choanae and down to the level of the tongue. MRI showed a heterogenous polypoid mass originating from the left middle meatus vs. nasal cavity, with characteristics favoring an aggressive tumor. The patient was taken for interventional radiology (IR) embolization and nasal endoscopy. Biopsy showed the left nasal mass contained granulation tissue and the palatal mass consisted of necrotic tissue. He was taken for second-stage endoscopic sinus surgery with plans for extensive reconstruction if necessary. Extensive polyposis was found without gross evidence of an aggressive tumor. The anterior polyposis was debulked and the polyp was cut at its root to allow for removal of the nasopharyngeal/oropharyngeal portion through the mouth. He was able to be discharged on the same day and his postoperative recovery was uncomplicated. Angiomatous nasal polyps are uncommon, share features of aggressive tumors on imaging, and require angiography and biopsy to safely rule out malignancy. Endoscopic surgical resection typically results in good outcomes and low recurrence rates.

Efficacy and safety of tolvaptan in cirrhotic patients: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND AND AIMS: Tolvaptan has been approved for the management of cirrhosis-related complications according to the Japanese and Chinese practice guidelines, but not the European or American practice guidelines in view of FDA warning about its hepatotoxicity. This study aimed to systematically evaluate its efficacy and safety in cirrhosis. METHODS: The PubMed, EMBASE, and Cochrane library databases were searched to identify randomized controlled trials (RCTs) evaluating the efficacy and/or safety of tolvaptan in cirrhosis. Risk ratios (RRs) and weight mean differences (WMDs) were calculated. The incidence of common adverse events (AEs) was pooled. RESULTS: Eight RCTs were included. Tolvaptan was significantly associated with higher rates of improvement of ascites (RR = 1.49, P < 0.001) and hyponatremia (RR = 1.80, P = 0.005) and incidence of any AEs (RR = 1.18, P = 0.003), but not serious AEs (RR = 0.86, P = 0.410). Tolvaptan was significantly associated with reductions in body weight (WMD = -1.30 kg, P < 0.001) and abdominal circumference (WMD = -1.71 cm, P < 0.001), and increases in daily urine volume (WMD = 1299.84 mL, P < 0.001) and serum sodium concentration (WMD = 2.57 mmol/L, P < 0.001). The pooled incidences of dry mouth, thirst, constipation, and pollakiuria were 16%, 24%, 6%, and 17%, respectively. CONCLUSION: Short-term use of tolvaptan may be considered in cirrhotic patients with ascites who have inadequate response to conventional diuretics and those with hyponatremia.

[Figure: see text].

Multistage O2-producing liposome for MRI-guided synergistic chemodynamic/chemotherapy to reverse cancer multidrug resistance.

Reduced drug uptake and elevated drug efflux are two major mechanisms in cancer multidrug resistance (MDR). In the present study, a new multistage O2-producing liposome with NAG/R8-dual-ligand and stimuli-responsive dePEGylation was developed to address the abovementioned issues simultaneously. The designed C-NAG-R8-PTXL/MnO2-lip could also achieve magnetic resonance imaging (MRI)-guided synergistic chemodynamic/chemotherapy (CDT/CT). In vitro and in vivo studies showed that C-NAG-R8-PTXL/MnO2-lip enhanced circulation time by PEG and targeted the tumor site. After tumor accumulation, endogenous l-cysteine was administered, and the PEG-attached disulfide bond was broken, resulting in the dissociation of PEG shells. The previously hidden positively charged R8 by different lengths of PEG chains was exposed and mediated efficient internalization. In addition, the oxygen (O2) generated by C-NAG-R8-PTXL/MnO2-lip relieved the hypoxic environment within the tumor, thus reducing the efflux of chemotherapeutic drug. O2 was able to burst liposomes and triggered the release of PTXL. The toxic hydroxyl radical (·OH), which was produced by H2O2 and Mn2+, strengthened CDT/CT. C-NAG-R8-PTXL/MnO2-lip was also used as MRI contrast agent, which blazed the trail to rationally design theranostic agents for tumor imaging.

Dynamically evolving piezoelectric nanocomposites for antibacterial and repair-promoting applications in infected wound healing.

Wound healing from bacterial infections is one of the major challenges in the biomedical field. The traditional single administration methods are usually accompanied with side effects or unsatisfactory efficacy. Herein, we design dynamically evolving antibacterial and repair-promoting nanocomposites (NCs) by in situ self-assembling of zeolitic imidazolate framework-8 (ZIF-8) on the surface of barium titanate (BTO), and further loading with a small amount of ciprofloxacin (CIP). The new strategy of combining pH-stimulated drug delivery and ultrasound-controlled sonodyamics has the potential to dynamically evolve in infected wound sites, offering a multifunctional therapy. In vitro study demonstrates that the enhancement generation of reactive oxygen species through the sonodynamic process due to the heterostructures and a small amount of CIP released in an acidic environment are synergistically antibacterial, and the inhibition rate was >99.9%. In addition, reduced sonodynamic effect and Zn2+ generated along with the gradual degradation of ZIF-8 simultanously promote cell migration and tissue regeneration. The in vivo study of full-thickness skin wounds in mouse models demonstrate a healing rate of 99.3% could be achieved under the treatment of BTO@ZIF-8/CIP NCs. This work provides a useful improvement in rational design of multi-stimulus-responsive nanomaterials for wound healing. STATEMENT OF SIGNIFICANCE: A novel piezoelectric nanocomposite was proposed to realize sonodynamic therapy and pH-stimulated drug releasing simultaneously in wound healing treatment. The dynamically evolving structure of the piezoelectric nanocomposite in acidic microenvironment has been theoretically and experimentally verified to contribute to a continuous variation of sonodymanic strength, which accompanied with the gradual releasing of drug and biocompatible Zn2+effectively balanced antibacterial and repair-promoting effects. Both of the in vitro and in vivo study demonstrated that the strategy could significantly accelerate wound healing, inspiring researchers to optimize the design of multi-stimulus-responsive nanomaterials for various applications in biomedical and biomaterial fields.

Tooth Wear and Tribological Investigations in Dentistry.

Dental or tooth wear is a physiological process in the life cycle of teeth. Loss of the occlusal surface may cause excessive tooth wear. Several factors may contribute to tooth wear with different intensities and duration in the oral cavity. The oral cavity is generally compared to a tribological system to determine the various types of wear between teeth and restorative materials and assess the amount of dental wear. However, it is challenging to investigate in vitro and in vivo wear owing to the complexity of tooth wear; thus, a clear correlation between in vitro and in vivo data could not be established. This review is aimed at providing an insight into the etiology of tooth wear and tribological investigations in dentistry.

Self-Propelled Nanomotors with an Alloyed Engine for Emergency Rescue of Traumatic Brain Injury.

In severe traumatic brain injury (sTBI), acute oxidative stress and inflammatory cascades rapidly spread to cause irreversible brain damage and low survival rate within minutes. Therefore, developing a feasible solution for the quick-treatment of life-threatening emergency is urgently demanded to earn time for hospital treatment. Herein, Janus catalysis-driven nanomotors (JCNs) are carefully constructed via plasma-induced alloying technology and sputtering-caused half-coating strategy. The theoretical calculation and experiment results indicate that the heteroatom-doping alloyed engine endows JCNs with much higher catalytic activity for removing reactive oxygen species and reactive nitrogen species than common Pt-based engines. When JCNs are dropped to the surface of the ruptured skull, they can effectively catalyze endogenous hydrogen peroxide, which induces movement as fuels to promote JCNs to deep brain lesions for further nanocatalyst-mediated cascade-blocking therapy. The results demonstrate that the JCNs successfully block the inflammatory cascades, thereby reversing multiple behavioral defects and dramatically declining the mortality of sTBI mice. This work provides a revolutionary nanomotor-based strategy to sense brain injury and scavenge oxidative stress. Meanwhile, the JCNs provide a feasible strategy to adapt various first-aid scenarios due to their self-propelled movement combined with highly multienzyme-like catalytic activity, exhibiting tremendous therapeutic potential to help people for emergency pretreatment.

Novel nanofibrous scaffolds for water filtration with bacteria and virus removal capability.

We demonstrate a new class of composite fibrous membranes, consisting of an ultra-fine cellulose nanofibrous network infused into an electrospun polyacrylonitrile (PAN) nanofibrous scaffold on a melt-blown polyethylene terephthalate (PET) non-woven substrate for water purification. Depending on the infusion process and the ultra-fine cellulose nanofibers (UFCNs) used [e.g. modified ultra-fine cellulose nanofibers (m-UFCNs) or microcrystalline cellulose nanofibers (MCCNs)], different nanostructured scaffolds were formed as seen by electron microscopy. Membranes with UFCNs consist of an interwoven two-dimensional ultra-fine nanofibrous network that is deeply entangled with the electrospun scaffold and organized in a quasi-three-dimensional fashion, while those with MCCNs tend to locally wrap around the electrospun scaffolding nanofibers without forming a major network. Filtration tests illustrated that both membranes, while maintaining high permeation flux, exhibited excellent retention capabilities for simultaneous sieving for bacteria and adsorption for viruses.

Synthesis of bio-based methylcyclopentadiene via direct hydrodeoxygenation of 3-methylcyclopent-2-enone derived from cellulose.

The exploration of highly efficient processes to convert renewable biomass to fuels and value-added chemicals is stimulated by the energy and environment problems. Herein, we describe an innovative route for the production of methylcyclopentadiene (MCPD) with cellulose, involving the transformation of cellulose into 3-methylcyclopent-2-enone (MCP) and subsequent selective hydrodeoxygenation to MCPD over a zinc-molybdenum oxide catalyst. The excellent performance of the zinc-molybdenum oxide catalyst is attributed to the formation of ZnMoO3 species during the reduction of ZnMoO4. Experiments reveal that preferential interaction of ZnMoO3 sites with the C=O bond instead of C=C bond in vapor-phase hydrodeoxygenation of MCP leads to highly selective formations of MCPD (with a carbon yield of 70%).

Research advances in preparation and application of chitosan nanofluorescent probes.

Nanofluorescent material is developing rapidly as a new type of material. Nanofluorescent probes have broad application prospects in biological analysis, drug metabolism, and semiconductor optical materials. Chitosan is non-toxic and rich in nature which has good biocompatibility, and it can be combined with fluorescent probes. Therefore, the preparation and application of Nanofluorescent probes using chitosan as a carrier is summarized in this article. Fluorescent probes can be combined with other different materials through different reaction mechanisms, and the prepared composite materials can be widely used in biomaterials, sewage treatment, medicine and other fields.

Icariin promotes the proliferation and differentiation of osteoblasts from the rat mandible by the Wnt/ß­catenin signalling pathway.

Icariin (ICA) has been suggested to restore osteogenic function. Many bone defect diseases involve the mandible, which performs distinct functions and responds differently to stimuli from other bones. However, there are few reports describing the effect and mechanism of ICA on mandibular cells. Therefore, the aim of the present study was to determine the effect of ICA on the proliferation and differentiation of osteoblastic cells isolated from the rat mandible and to determine whether the Wnt/ß­catenin signalling pathway participates in this effect. The present study established an osteoblastic cell line from the rat mandible. ICA at concentrations between 0.15 and 15 µM promoted the proliferation and differentiation of osteoblastic cells following a 72 h incubation. Furthermore, ICA elevated the mRNA expression levels of ß­catenin, runt­related transcription factor 2, cyclin D1 and alkaline phosphatase in osteoblastic cells, and these effects were inhibited by the Wnt/ß­catenin pathway inhibitor Dickkopf­1; thus, the Wnt/ß­catenin signalling pathway may be involved with the ICA­induced proliferation and differentiation of osteoblasts from the rat mandible. In conclusion, these results support the osteogenic effects of ICA (0.15 to 15 µM) on osteoblastic cells from the rat mandible and the participation of the Wnt/ß­catenin signalling pathway.

Amine-functionalized, multi-arm star polymers: A novel platform for removing glyphosate from aqueous media.

We describe a novel method for efficiently removing glyphosate from aqueous media via adsorption onto highly functionalized star-shaped polymeric particles. These particles have a polystyrene core with more than 35 attached methacrylate polymer arms, each containing a plurality of pendant amines (poly(dimethylamino ethyl methacrylate): PDMAEMA) that are partially protonated in water. Kinetic studies demonstrate that these star-polymers successfully remove up to 93% of glyphosate present in aqueous solution (feed concentration: 5 ppm), within 10 min contact time, outperforming activated carbon, which removed 33% after 20 min. On these star-polymers, glyphosate adsorption closely follows the Langmuir model indicating monolayer coverage at most. Ionic interaction between the protonated amines and glyphosate's dissociated carboxylic and phosphoric acid groups lead to effective glyphosate capture even at feed concentrations below 1 ppm. Surface charge of these star polymers and dissociation of glyphosate are both influenced by pH, thus glyphosate removal efficiency increases from 63% to 93% when pH increases from 4.2 to 7.7. NMR studies conducted with butylamine as a proxy for these polymeric particles confirm that the amine group binds with both glyphosate's carboxylic and phosphoric acid groups when its concentrations are in a 2:1 or higher molar ratio with glyphosate.

Heterogenous expression of Pyrus pyrifolia PpCAD2 and PpEXP2 in tobacco impacts lignin accumulation in transgenic plants.

Lignin, a natural macromolecular compound, plays an important role in the texture and taste of fruit. Hard end is a physiological disorder of pear fruit, in which the level of lignification in fruit tissues is dramatically elevated. Cinnamyl alcohol dehydrogenase and expansin genes (PpCAD2 and PpEXP2, respectively) exhibit higher levels of expression in 'Whangkeumbae' (Pyrus pyrifolia) pear fruit exhibiting this physiological disorder, relative to control fruit without symptoms. These genes were isolated from pear fruit and subsequently expressed in tobacco (Nicotiana tabacum) to investigate their function. Histochemical staining for lignin revealed that the degree of lignification in leaf veins and stem tissues increased in plants transformed with sense constructs and decreased in plants transformed with antisense constructs of PpCAD2. The expression of native NtCADs was also inhibited in the antisense PpCAD2 transgenic tobacco. Sense and antisense PpCAD2 transgenic tobacco exhibited an 86.7% increase and a 60% decrease in CAD activity, respectively, accompanied by a complementary response in lignin content in root tissues. The basal portion of the stem in PpEXP2 transgenic tobacco was bent and highly lignified. Additionally, the level of cellulose also increased in the stem of PpEXP2 transgenic tobacco. Collectively, these results suggested that PpCAD2 and PpEXP2 genes play a significant role in lignin accumulation in transgenic tobacco plants, and it is inferred that these two genes may also participate in the increased lignification observed in hard end pear fruit.