[Evaluation of CT angiography vascular localization combined with refined three-dimensional printing in guiding the resection and reconstruction of complex oral cancer].

Objective: To evaluate the effect of vascular localization using computerized tomography angiography (CTA) combined with refined three dimensional (3D) printing in guiding the resection and reconstruction of complex oral cancer. Methods: From December 2013 to July 2017, the clinical data of 30 patients with complex oral cancer enrolled in the Hunan Cancer Hospital were retrospectively analyzed. 15 patients received CTA+ 3D assisted surgery, while the other 15 patients underwent traditional surgery. In CTA+ 3D assisted surgery group, CT and Magnetic Resonance Imaging (MRI) data were combined with CTA to print refined solid 3D model and surgical guide plate. The preoperative and intraoperative virtual surgical system and the operative experience were combined for preoperative evaluation and surgery. In traditional surgery group, preoperative evaluation and surgery were performed according to imaging data and surgeons' clinical experience. Operative time, intraoperative blood loss, hospital stay and local recurrence rate were compared between the two groups. Results: In CTA+ 3D assisted surgery group, one patient gave up surgical treatment after intuitively watching the lesion through the 3D model, and the remaining 14 patients underwent surgery as planned. All the 15 patients in traditional surgery group received surgery. But the preoperative plans of three patients were temporarily and passively modified due to insufficient preoperative evaluation. The average intraoperative blood loss was(320.1±27.2)ml in CTA+ 3D assisted surgery group and(430.2±30.3)ml in traditional surgery group. Mean operation time was(440.3±19.2)min and(552.2±23.3)min, respectively. Mean hospitalization time was (20.4±3.2)d and (25.1±3.7)d, respectively. The differences were all statistically significant (all P<0.05). 1 year and 3 years local recurrence rates were 9.1% and 28.6% in CTA+ 3D assisted surgery group, as well as 14.3% and 50.4% in traditional surgery group with statistical significance (P<0.05). Conclusion: For complex oral cancer patients with difficulty in opening the mouth or postoperative recurrence, CTA vascular localization combined with fine 3D printing technology has significant advantages in the surgical process, surgical effect and postoperative evaluation index compared with traditional method using imaging data and clinical experience.

Osteoblast differentiation of rabbit adipose-derived stem cells by polyethylenimine-mediated BMP-2 gene transfection in vitro.

The aim of this study was to examine the efficiency of polyethylenimine-mediated transfection of the human bone morphogenetic protein-2 (BMP-2) gene into rabbit adipose-derived stem cells (ADSCs), and its effect on osteoblast differentiation. Adipose tissue was isolated from the necks of adult Japanese white rabbits and cultured in vitro to obtain ADSCs. Gene delivery of BMP-2 was mediated by polyethylenimine and stable transformants were selected by G-418. The expression of BMP-2 mRNA was confirmed by reverse transcription-polymerase chain reaction, and of the BMP-2 protein by ELISA. Osteocalcin and collagen type I were detected by western blot and by an alkaline phosphatase kit. Alizarin red S stain was also utilized to examine osteogenesis. The non-transfected group was considered as a control. In this study, we successfully derived ADSCs from rabbit adipose tissue. Through passages 3-6, the expression of CD29 and CD44 gradually increased, whereas the expression of CD34 and CD45 gradually decreased. Both mRNA and protein expression of BMP-2 were confirmed following polyethylenimine-mediated BMP-2 gene delivery. In addition, the expression of alkaline phosphatase, osteocalcin, and collagen type I was found to be upregulated and alizarin red S staining was positive in transfected ADSCs, indicating BMP-2-induced osteogenesis. Therefore, this study determined that polyethylenimine was able to mediate BMP-2 gene delivery and induce osteogenic differentiation of ADSCs.

[Effects of low-frequency pulsed wave ultrasound on the shear properties of the interface of vancomycin-loaded acrylic bone cement-stem].

Objective: To investigate the effects of low-frequency pulsed wave ultrasound on the shear properties of interface of the vancomycin -loaded acrylic bone cement-stem. Methods: The interfaces of 1% vancomycin-loaded acrylic bone cement-stem specimences were successfully manufactured and randomly divided into three groups: the control group, 450 mW/cm(2) ultrasound group and 1 200 mW/cm(2) ultrasound group, each group consisted of eight samples.Two ultrasound groups were exposed to a local ultrasonic field for 7 d, then immersed in PBS for 23 d, and the control groups were immersed in PBS for 30 d. After curing in air for 24 h, the shear strength of the stem-cement interface was determined by push-out test.The specimens were then photographed using SEM and analysed using Image-Pro Plus 6.0 to determine the porosity at the stem-cement interface. Results: The mean shear strength of stem-cement interface additionally decreased by 9% (P>0.05) and 17% (P<0.05) in 450 mW/cm(2) ultrasound group and 1 200 mW/cm(2) group respectively comparing with the control group, but no significant difference was found between the two ultrasound groups.The porosity at the stem-cement interface additionally increased by 44% (P>0.05) and 110% (P<0.05) in 450 mW/cm(2) ultrasound group and 1 200 mW/cm(2) group respectively comparing with the control group, furthermore.The porosity in 1 200 mW/cm(2) ultrasound group increased by 46% (P<0.05) comparing with the 450 mW/cm(2) group. There are much more fluid penetration along the stem-cement interface in ultrasound group . Conclusion: Low-frequency pulsed wave ultrasound signifiantly enhanced porosity and fluid penetration interface, and reduced the interface shear strength and initial stability.

Atomized paclitaxel liposome inhalation treatment of bleomycin-induced pulmonary fibrosis in rats.

We sought to determine the efficacy of atomized paclitaxel liposome inhalation treatment of pulmonary fibrosis in a bleomycin-induced rat model. Forty male Sprague-Dawley rats were randomly divided into four groups: healthy control, pulmonary fibrosis without treatment, paclitaxel liposome inhalation-treated, and intravenous paclitaxel liposome-treated. Fibrosis was induced by bleomycin injection. A total of 20 mg/kg paclitaxel liposome was administered by inhalation every other day for a total of 10 doses. The intravenous group received 5 mg/kg paclitaxel liposome on days 1, 7, 14, and 21. We observed the general condition, weight change, survival index, and pathological changes in the lung tissue of the rats. Quantitative analysis of collagen types I and III and transforming growth factor (TGF)-ß1 expression in the lungs was also performed. The paclitaxel liposome inhalation and intravenous delivery methods improved survival index and pulmonary fibrosis Ashcroft score, and decreased the thickness of the alveolar interval. No obvious difference was found between the two groups. Compared with the untreated group, paclitaxel liposome inhalation and intravenous injection significantly reduced the levels of collagen types I and III and TGF-ß1 expression equally. In conclusion, atomized paclitaxel liposome inhalation protects against severe pulmonary fibrosis in a bleomycin-induced rat model. This delivery method has less systemic side effects and increased safety over intravenous injection.

[A two-dimensional photographic and three-dimensional digital dental model comparative analysis in maxillary anterior teeth].

Objective: To assess the accuracy of two-dimensional (2D) photographs in measuring esthetic parameters of the maxillary anterior teeth by comparing them with measurements obtained from three-dimensional (3D) dental models. Methods: A total of one hundred volunteers (49 males, 51 females, aged 18-23 years) were recruited from School and Hospital of Stomatology, Wuhan University from January to February 2024. 3D digital models of their dentitions were obtained using an intraoral scanner, and standardized frontal 2D intraoral photographs were captured with a digital camera. The lengths, widths and width/length ratio of the bilateral incisors, lateral incisors and canines were measured on both the 3D digital models and the 2D intraoral photographs. The width ratios of adjacent maxillary anterior were also calculated on the 2D intraoral photographs and the frontal view of 3D digital models. Results: The widths of lateral incisors [(5.85±0.60) mm] and canines [(4.73±0.71) mm] and the lengths of canines [(8.72±0.96) mm] in the 2D intraoral photographs were significantly lower than those in 3D digital models [(6.65±0.59), (7.76±0.60), (8.90±0.86) mm] (t=-18.24, P<0.001; t=-54.43, P<0.001; t=-4.40, P<0.001), while there were no significant differences in the lengths and widths of the other teeth (P>0.05). The width/length ratios measured from the 2D intraoral photographs for the lateral incisors and canines (0.74±0.08, 0.55±0.08) were significantly lower than those measured in the 3D digital models (0.84±0.09, 0.88±0.09) (t=-19.68, P<0.001; t=-50.21, P<0.001), and the width/length ratio of the central incisors showed no significant difference between the two groups (P>0.05). The width ratios of canines/lateral incisors and lateral incisors/central incisors measured on the 2D intraoral photographs (0.72±0.06, 0.85±0.11) were significantly smaller than those measured in the frontal view of 3D digital models (0.75±0.06, 0.89±0.11) (t=-9.31, P<0.001; t=-6.58, P<0.001). Conclusions: There is a difference between 2D and 3D measurement results of teeth in the esthetic area and the magnitude of the difference varies with their position in the dental arch. When analyzing the measurement of the anterior teeth, it is necessary to choose the appropriate method according to the target tooth position.

[Incidence and prognosis of olfactory and gustatory dysfunctions related to infection of SARS-CoV-2 Omicron strain: a national multi-center survey of 35 566 population].

Objective: This cross-sectional investigation aimed to determine the incidence, clinical characteristics, prognosis, and related risk factors of olfactory and gustatory dysfunctions related to infection with the SARS-CoV-2 Omicron strain in mainland China. Methods: Data of patients with SARS-CoV-2 from December 28, 2022, to February 21, 2023, were collected through online and offline questionnaires from 45 tertiary hospitals and one center for disease control and prevention in mainland China. The questionnaire included demographic information, previous health history, smoking and alcohol drinking, SARS-CoV-2 vaccination, olfactory and gustatory function before and after infection, other symptoms after infection, as well as the duration and improvement of olfactory and gustatory dysfunction. The self-reported olfactory and gustatory functions of patients were evaluated using the Olfactory VAS scale and Gustatory VAS scale. Results: A total of 35 566 valid questionnaires were obtained, revealing a high incidence of olfactory and taste dysfunctions related to infection with the SARS-CoV-2 Omicron strain (67.75%). Females(χ2=367.013, P<0.001) and young people(χ2=120.210, P<0.001) were more likely to develop these dysfunctions. Gender(OR=1.564, 95%CI: 1.487-1.645), SARS-CoV-2 vaccination status (OR=1.334, 95%CI: 1.164-1.530), oral health status (OR=0.881, 95%CI: 0.839-0.926), smoking history (OR=1.152, 95%CI=1.080-1.229), and drinking history (OR=0.854, 95%CI: 0.785-0.928) were correlated with the occurrence of olfactory and taste dysfunctions related to SARS-CoV-2(above P<0.001). 44.62% (4 391/9 840) of the patients who had not recovered their sense of smell and taste also suffered from nasal congestion, runny nose, and 32.62% (3 210/9 840) suffered from dry mouth and sore throat. The improvement of olfactory and taste functions was correlated with the persistence of accompanying symptoms(χ2=10.873, P=0.001). The average score of olfactory and taste VAS scale was 8.41 and 8.51 respectively before SARS-CoV-2 infection, but decreased to3.69 and 4.29 respectively after SARS-CoV-2 infection, and recovered to 5.83and 6.55 respectively at the time of the survey. The median duration of olfactory and gustatory dysfunctions was 15 days and 12 days, respectively, with 0.5% (121/24 096) of patients experiencing these dysfunctions for more than 28 days. The overall self-reported improvement rate of smell and taste dysfunctions was 59.16% (14 256/24 096). Gender(OR=0.893, 95%CI: 0.839-0.951), SARS-CoV-2 vaccination status (OR=1.334, 95%CI: 1.164-1.530), history of head and facial trauma(OR=1.180, 95%CI: 1.036-1.344, P=0.013), nose (OR=1.104, 95%CI: 1.042-1.171, P=0.001) and oral (OR=1.162, 95%CI: 1.096-1.233) health status, smoking history(OR=0.765, 95%CI: 0.709-0.825), and the persistence of accompanying symptoms (OR=0.359, 95%CI: 0.332-0.388) were correlated with the recovery of olfactory and taste dysfunctions related to SARS-CoV-2 (above P<0.001 except for the indicated values). Conclusion: The incidence of olfactory and taste dysfunctions related to infection with the SARS-CoV-2 Omicron strain is high in mainland China, with females and young people more likely to develop these dysfunctions. Active and effective intervention measures may be required for cases that persist for a long time. The recovery of olfactory and taste functions is influenced by several factors, including gender, SARS-CoV-2 vaccination status, history of head and facial trauma, nasal and oral health status, smoking history, and persistence of accompanying symptoms.

[Research progress in titanium mesh application for bone augmentation in oral implantology].

Guided bone regeneration technique is a conventional method to repair various bone defects among series of techniques for bone augmentation around implant. Due to the excellent mechanical properties and biological compatibility, titanium mesh has unique advantages in the application of guided bone regeneration technology, such as broad clinical indications, high stability in osteogenesis. Though there are still some complications during the application of titanium mesh, a number of studies have tried to prevent the complications, so as to increase the success rate of bone augmentation surgery. This review elaborates the characteristics of titanium mesh, conventional clinical applications, common complications in application, and the research progress of its application and improvement, in order to provide reference for the improvement of titanium mesh in clinical and research applications.

The temporal expression and localization of extracellular matrix metalloproteinase inducer (EMMPRIN) during the development of periodontitis in an animal model.

BACKGROUND AND OBJECTIVE: We previously demonstrated extracellular matrix metalloproteinase inducer (EMMPRIN) was associated with the matrix metalloproteinases production of human periodontitis. The aim of this study was to investigate the temporal expression and localization of EMMPRIN during ligature-induced periodontitis in rats. MATERIAL AND METHODS: Periodontitis was induced in rats by placing a thread around the cervix of the first mandibular molar. Animals were killed 3, 7, 11, 15 or 21 d after ligation. Mandibles were processed for paraffin sections and stained with hematoxylin and eosin or picrosirius red. The distance from the amelocemental junction to the alveolar crest (ACJ-AC) and the area fraction (Area%) of collagen fibers were measured. EMMPRIN was examined by immunohistochemistry and quantified by positive cell counting. Correlation analyses were then performed. RESULTS: Histologically, alveolar bone was gradually destroyed from day 3 to 11 and then stabilized. Collagen fibers were slightly dissociated on day 3 and extensively broken on day 7. They were reconstructed from day 11 to 21. EMMPRIN was localized predominantly in infiltrating cells and adjacent fibroblasts in interdental gingiva. The number of EMMPRIN-positive cells increased on day 3, peaked on day 7 and then gradually subsided from day 11 to 21. Statistically, there was a moderate positive correlation regarding the ACJ-AC distance (r = 0.552, p < 0.01) and a strong negative correlation with the Area% of collagen fibers (r = -0.808, p < 0.01). In gingival epithelium, the immunoreactivity was extremely strong in basal layer cells and sulcular epithelial cells in health. It was greatly enhanced in the inflamed conditions on days 3 and 7. In the interradicular bone, EMMPRIN was localized in the osteoclasts on days 3 and 7, as well as in the osteoblasts from day 11 onwards. CONCLUSION: The expression and localization of EMMPRIN are temporally varied during the development of periodontitis. In addition, the inflammation-dependent expression of EMMPRIN might be involved in alveolar bone resorption and collagen breakdown.

Bactericidal and biocompatible properties of TiN/Ag multilayered films by ion beam assisted deposition.

Nanoscale TiN/Ag multilayered films of thickness 500 nm were synthesized on AISI317 stainless steel by ion beam assisted deposition (IBAD) with the modulation period of 4, 5, 6, 7.5, and 12 nm. The bactericidal and biocompatible properties of TiN/Ag multilayered films were investigated through Gram negative E. coli bacteria and L929 cells (mice fibroblast) as well as human umbilical vein endothelial cells (HUVEC). The results show that the TiN/Ag multilayered films with the modulation period of 7.5 nm possess the strongest bactericidal property. The cytotoxicity grade of TiN/Ag multilayered coating with the modulation periods of 7.5 nm, 12 nm is in 0-1 scope, which indicates this film has no cytotoxicity to L929. HUVEC on TiN/Ag multilayered film grows well and shows good cellularity. Auger electronic spectroscopy reveals the relationship between the structure of TiN/Ag multilayered film and the biomedical properties.

[The application of three-dimensional printing technique combined with three-dimensional reconstruction in mandibular fracture].

Objective:To explore the value and significance of the combination of 3D printing and spiral CT three-dimensional reconstruction in the diagnosis and treatment of common mandibular fractures. Method:Forty patients with mandibular fracture were collected. They were randomly divided into traditional operation group and 3D printing combined with three-dimensional reconstruction operation group. The differences between the two groups were compared according to the operation time and the recovery of fracture. Result:The operation time and trauma of 3D printing combined with three-dimensional reconstruction group were significantly better than those of traditional operation group, and the former was better than the latter （P<0.05）. Conclusion: 3D printing combined with three-dimensional reconstruction operation method realized the concept of individualized, precise and minimally invasive comprehensive treatment, which is worthy of clinical promotion.

Chitosan-Based Extrafibrillar Demineralization for Dentin Bonding.

Instability of resin-dentin bonds is the Achilles' heel of adhesive dentistry. To address this problem, a chelate-and-rinse extrafibrillar dentin demineralization strategy has been developed that keeps intrafibrillar minerals within collagen fibrils intact to prevent activation of endogenous proteases that are responsible for collagen degradation within hybrid layers. The objective of the present study was to evaluate the potential of using chitosan >40 kDa as an antimicrobial extrafibrillar dentin-chelating agent to enhance bond durability. Transmission electron microscopy provided evidence for retention of intrafibrillar minerals and smear plugs in dentin conditioned with 1 wt% chitosan. Analyzed by Kruskal-Wallis analysis of variance, Dunn's statistic, and separate Mann-Whitney tests, tensile bond strengths to wet- and dry-bonded dentin indicated that chelating dentin with chitosan for 60 s prior to bonding did not result in a significant decline in resin-dentin bond strength when compared with that of phosphoric acid etching ( P > 0.05). Gelatinolytic activity within the hybrid layers was examined via in situ zymography after 24-h storage or after thermomechanical cycling and analyzed with 3-factor analysis of variance. After 24 h, enzymatic activity was detected only within completely demineralized phosphoric acid-etched dentin, with values derived from dry bonding significantly higher than those derived from wet bonding ( P < 0.05). Negligible fluorescence was detected within hybrid layers when dentin was conditioned with chitosan, even after thermomechanical cycling, as compared with the controls. Reduction in water permeability in chitosan-conditioned dentin, attributed to smear plug retention, also fostered long-term bond stability. Antibacterial testing performed with live/dead staining indicated that the acetic acid-solubilized chitosan possessed antibacterial activities against 3 single-species biofilms: Streptococcus mutans, Actinomyces naeslundii, and Enterococcus faecalis. Taken together, the new chitosan-based extrafibrillar demineralization strategy retains intrafibrillar minerals, reduces endogenous protease-initiated collagen degradation, prevents water permeation within hybrid layers, and kills bacteria on dentin surfaces, which are crucial factors for enhancing resin-dentin bond durability.

Protective effects of baicalin on ligature-induced periodontitis in rats.

BACKGROUND AND OBJECTIVE: Baicalin is a flavonoid compound purified from the medicinal plant, Scutellaria baicalensis Georgi, and has been reported to possess anti-inflammatory and antioxidant activities. The purpose of this study was to test the ability of baicalin to influence the progression of experimental periodontitis in rats, as well as the expression of cyclooxygenase-2 and inducible nitric oxide synthase. MATERIAL AND METHODS: Adult male Sprague-Dawley rats were subjected to placement of a nylon thread around the bilateral lower first molars and killed after 7 d. Baicalin (50, 100 or 200 mg/kg) was supplied to the animals by oral gavage, starting 1 d before the induction of periodontitis. The ligature group consisted of rats subjected to periodontitis and receiving vehicle (0.5% carboxymethylcellulose) alone. The alveolar bone loss and the area fraction occupied by collagen fibers were assessed. The expression of cyclooxygenase-2 and inducible nitric oxide synthase protein in the gingiva were detected by immunohistochemistry and western blotting. RESULTS: Baicalin-treated groups presented with lower alveolar bone loss than that of the ligature group, reaching statistical significance at the dose of 200 mg/kg (p = 0.009). The area fraction of collagen fibers was significantly higher in the baicalin (200 mg/kg)-treated group than in the ligature group (p = 0.047). Baicalin treatment significantly down-regulated the protein expression for cyclooxygenase-2 (p = 0.000) and inducible nitric oxide synthase (p = 0.003), compared with the ligature group. CONCLUSION: Baicalin protects against tissue damage in ligature-induced periodontitis in rats, which might be mediated, in part, by its inhibitory effect on the expression of cyclooxygenase-2 and inducible nitric oxide synthase. These activities could support the continued investigation of baicalin as a potential therapeutic agent in periodontal disease.

Vascularization in Craniofacial Bone Tissue Engineering.

Craniofacial bones, separate from the appendicular skeleton, bear a significant amount of strain and stress generated from mastication-related muscles. Current research on the regeneration of craniofacial bone focuses on the reestablishment of an elaborate vascular network. In this review, current challenges and efforts particularly in advances of scaffold properties and techniques for vascularization remodeling in craniofacial bone tissue engineering will be discussed. A microenvironment of ischemia and hypoxia in the biomaterial core drives propagation and reorganization of endothelial progenitor cells (EPCs) to assemble into a primitive microvascular framework. Co-culture strategies and delivery of vasculogenic molecules enhance EPCs' differentiation and stimulate the host regenerative response to promote vessel sprouting and strength. To optimize structural and vascular integration, well-designed microstructures of scaffolds are biologically considered. Proper porous structures, matrix stiffness, and surface morphology of scaffolds have a profound influence on cell behaviors and thus affect revascularization. In addition, advanced techniques facilitating angiogenesis and vaculogenesis have also been discussed. Oxygen delivery biomaterials, scaffold-free cell sheet techniques, and arteriovenous loop-induced axial vascularization strategies bring us new understanding and powerful strategies to manage revascularization of large craniofacial bone defects. Although promising histological results have been achieved, the efficient perfusion and functionalization of newly formed vessels are still challenging.

Cervical infection with descending mediastinitis: a review of six cases.

The aim of this study was to retrospectively review cases of cervical infection with descending mediastinitis, and to analyse the clinical character, diagnosis and treatment of this infection. Six patients were identified from December 1998 to June 2005. Their aetiology, associated systemic diseases, bacteriology, radiology, treatments and outcomes were reviewed. Four cases resulted from odontogenic infection, one from upper airway infection, and one had an unknown cause. Diffuse swelling in face and neck, chest distress, tachypnea, and fever were the main symptoms. Chest radiography showed a widening of the upper mediastinal shadow in four patients. Four patients underwent computed tomographic scanning that confirmed the diagnosis of descending mediastinitis, which suggests that routine use of this scan be highly recommended for early detection. Six different pathogens were identified through pus and blood culture. All patients underwent surgical drainage. Three patients received a tracheotomy. Of the six patients, four achieved good results, and there were two deaths. Early surgical drainage remains the main treatment for cervical infection with descending mediastinitis. Delayed diagnosis, inadequate drainage and multidrug-resistant bacterial infection were responsible for the deaths.

Investigating the ability of nanoparticle-loaded hydroxypropyl methylcellulose and xanthan gum gels to enhance drug penetration into the skin.

Nanoparticle-loaded topical formulations can disrupt drug aggregation through controlled drug-nanoparticle interactions to enhance topical drug delivery. However, the complex relationship between the drug, nanoparticle and formulation vehicle requires further understanding. The aim of this study was to use nanoparticle-loaded hydroxypropyl methylcellulose (HPMC) and xanthan gum gels to probe how the drug, nanoparticle and formulation vehicle interactions influenced the delivery of an aggregated drug into the skin. Tetracaine was chosen as a model drug. It was loaded into HPMC and xanthan gum gels, and it was presented to porcine skin using infinite and finite dosing protocols. Gel infinite doses showed no important differences in tetracaine skin permeation rate, but HPMC gel finite doses delivered the drug more efficiently (46.99±7.96µg/cm2/h) compared to the xanthan gum (1.16±0.14µg/cm2/h). Finite doses of the nanoparticle-loaded HPMC gel generated a 10-fold increase in drug flux (109.95±28.63µg/cm2/h) compared to the equivalent xanthan gum system (14.19±2.27µg/cm2/h). Rheology measurements suggested that the differences in the gels ability to administer the drug into the skin were not a consequence of gel-nanoparticle interactions rather, they were a consequence of the dehydration mediated diffusional restriction imparted on the drug by xanthan gum compared to the viscosity independent interactions of HPMC with the drug.

Investigating the influence of drug aggregation on the percutaneous penetration rate of tetracaine when applying low doses of the agent topically to the skin.

Understanding the molecular aggregation of therapeutic agents is particularly important when applying low doses of a drug to the surface of the skin. The aim of this study was to understand how the concentration of a drug influenced its molecular aggregation and its subsequent percutaneous penetration after topical application. A model drug tetracaine was shown to form a series of different aggregates across the µM (fluorescence spectroscopy) to mM (light scattering analysis) concentration range. The aggregate formation process was sensitive to the pH of the vehicle in which the drug was dissolved (pH 4, critical aggregation concentration (CAC) - 11 µM; pH 8, CAC - 7 µM) and it appeared to have an impact upon the drug's percutaneous penetration. At pH 4, increasing the concentration of the drug in the donor solution decreased the skin permeability coefficient (Kp) of tetracaine (13.7 ± 4.3 × 10(-3)cm/h to 0.06 ± 0.02 × 10(-3)cm/h), whilst at pH 8, it increased the Kp (29.9 ± 9.9 × 10(-3)cm/h to 75.1 ± 41.7 × 10(-3)cm/h). These data trends were reproduced in a silicone membrane and this supported the notion that the more polar aggregates formed at pH 4 acted to decrease the proportion of species available to pass through the skin, whilst the more hydrophobic aggregates formed in pH 8 increased the membrane diffusing species.

Size effect of polydiacetylene vesicles functionalized with glycolipids on their colorimetric detection ability.

In this paper, the size effect of the polydiacetylene vesicles functionalized with glycolipids on their colorimetric detection ability has been studied. Polydiacetylene vesicles in which were incorporated glycolipids acted as a model system for the affinochromatic property. Visible color changes from blue to red could be observed to the naked eye owing to Con A binding to the sugar moiety and be detected quantitatively by the visible absorption spectrum. In the experiment, small and uniform vesicles were obtained after extrusion through membranes with different pore sizes. The morphology and mean size distribution of the extruded vesicles were studied by transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. Our work shows that the smaller the vesicles are, the stronger is the effect, making the detection of Con A easier. The results may apply to the sensitivity enhancement of polydiacetylene biosensors for the recognition of other biomolecules.

Study of differential properties of fibrochondrocytes and hyaline chondrocytes in growing rabbits.

We aimed to build a culture model of chondrocytes in vitro, and to study the differential properties between fibrochondrocytes and hyaline chondrocytes. Histological sections were stained with haematoxylin and eosin so that we could analyse the histological structure of the fibrocartilage and hyaline cartilage. Condylar fibrochondrocytes and femoral hyaline chondrocytes were cultured from four, 4-week-old, New Zealand white rabbits. The production of COL2A1, COL1OA1, SOX9 and aggrecan was detected by real time-q polymerase chain reaction (RT-qPCR) and immunoblotting and the differences between them were compared statistically. Histological structures obviously differed between fibrocartilage and hyaline cartilage. COL2A1 and SOX9 were highly expressed within cell passage 2 (P2) of both fibrochondrocytes and hyaline chondrocytes, and reduced significantly after cell passage 4 (P4). The mRNA expressions of COL2A1 (p=0.05), COL10A1 (p=0.04), SOX9 (p=0.03), and aggrecan (p=0.04) were significantly higher in hyaline chondrocytes than in fibrochondrocytes, whereas the expression of COL1A1 (p=0.02) was the opposite. Immunoblotting showed similar results. We have built a simple and effective culture model of chondrocytes in vitro, and the P2 of chondrocytes is recommended for further studies. Condylar fibrocartilage and femoral hyaline cartilage have unique biological properties, and the regulatory mechanisms of endochondral ossification for the condyle should be studied independently in the future.