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Biomedical subjects

Gang Shen

Publications and source records attributed to Gang Shen.

At least 19 recordsLinked to original sources
PubMed2026

Mechanisms of high-humidity hot air impingement blanching (HHAIB) on microbial counts, functional properties, phenolic profile transformation, and volatile compounds in celery stalks (Apium graveolens L.).

In this study, celery stalks were pretreated with different durations (0-150 s) of high-humidity hot air impingement blanching (HHAIB), followed by far-infrared radiation assisted pulsed vacuum freeze-drying (FIR-PVFD) at 60, 65, and 70 °C. The effects of HHAIB on the physicochemical properties, composition and transformation of phenolic compounds, volatile components, and antioxidant capacity of FIR-PVFD-dried celery stalks were systematically investigated. The results showed that HHAIB not only effectively reduced the counts of total mesophilic aerobic bacteria (TMAB) and total yeast and mold (TYM), but also decreased the relative activities of polyphenol oxidase (PPO) and lipoxygenase (LOX) by more than 91% after 90 s of treatment. HHAIB altered the cellular structure of celery stalks, shortened the drying time by 29.33-41.43%, and improved their hydration properties. HHAIB pretreatment promoted the conversion of bound phenolics to free phenolics in celery stalks, with significant increases in the contents of p-coumaric acid, apigenin, graveobioside A, and other components. The total free phenolic content increased by 56.99%, thus HHAIB enhanced the antioxidant activity. An electronic nose and sensory evaluation revealed that HHAIB-pretreated celery stalks better retained the characteristic herbal and pungent notes. GC-MS results indicated that HHAIB treatment optimized the aroma profile by regulating the contents and composition of terpenes, aldehydes, ketones, alcohols, and aromatic compounds.

Apium↗
PubMed2026

Causal Relationships Between Modifiable Risk Factors and Gastroesophageal Reflux Disease: A Two-Sample Mendelian Randomization Study.

INTRODUCTION: Gastroesophageal reflux disease (GERD) is a prevalent digestive disorder, yet the causal roles of modifiable risk factors remain unclear. This study aims to investigate the causal relationships between 28 modifiable risk factors (including obesity traits, mental health disorders, sleep traits, metabolic comorbidities, and serum parameters) and GERD using two-sample Mendelian randomization (MR). Gastroesophageal reflux disease (GERD). Our findings aim to inform targeted prevention and treatment strategies for GERD. METHODS: This study obtained data from extensive genome-wide association studies (GWAS). Pooled data associated with gastroesophageal reflux associations were obtained from the 23andMe Research team's research, which included a total of 129,080 cases of gastroesophageal reflux and 473,524 controls of European ancestry. We conducted a univariable Mendelian randomization (MR) analysis to ascertain whether genetic evidence of exposure demonstrated a statistically significant association with the risk of GERD. Subsequently, a multivariable MR analysis was carried out to estimate the independent effects of the exposures on GERD. RESULTS: Univariable MR analysis utilizing extensive GWAS data suggested that genetic factors such as BMI, Waist circumference, Arm fat mass (left and right), Leg fat mass (left and right), Attention Deficit and Hyperactivity Disorder (ADHD), Major Depressive Disorder (MDD), Schizophrenia, Negative emotions (including nervousness, anxiety, tension, or depression), Insomnia, Sleep apnea syndrome, Sleep duration, and Snoring, as well as Total cholesterol levels and Apolipoprotein B levels, are associated with the development of GERD. Multivariate Mendelian randomization of BMI and Negative emotion as correction factors showed that Waist circumference, Arm fat mass (left and right), Leg fat mass (left and right), ADHD, Insomnia, Sleep apnea syndrome, and Snoring were associated with an increased risk of GERD (p< 0.05). Conversely, longer sleep duration was associated with a reduced risk of GERD (p< 0.05). DISCUSSION: This MR study reveals novel causal mechanisms in GERD pathogenesis: (1) Peripheral adiposity (arm/leg fat mass) exerts independent effects beyond central obesity, indicating site-specific fat distribution significance; (2) ADHD emerges as a distinct psychiatric risk factor independent of mental disorders; (3) Sleep apnea operates through BMI-independent pathways. Collectively, these findings redefine GERD pathophysiology, highlighting fat depot specificity and brain-gut interactions as critical mechanistic drivers. CONCLUSION: Overall, our findings suggest that multiple risk factors are associated with the risk of GERD. These results provide a theoretical basis for controlling body weight and plasticity, improving sleep habits, and preventing and timely seeking medical attention to reduce the occurrence of psychiatric disorders, which will be important strategies to prevent and alleviate GERD.

Humans↗
PubMed2006

Epithelial cells in PDL are critical in resuming the integral relation between tooth root and supporting bone after trauma--a transplantation experiment.

OBJECTIVE: The aim of this study was to determine the response of the residual epithelial network following traumatic breakdown of the periodontal ligament (PDL). METHODS: Mandibular incisor sections with PDL (experimental) and sections denuded of PDL (control) from 4- to 6-week-old Wistar-Furth rats were transplanted into the defects created in the frontal bone of the recipient syngeneic rats. At intervals, the defects with implanted teeth roots were collected and processed for histological and biochemical examination. Immunolocalization of epithelial cells was performed to monitor their phenotypic changes during transplantation healing period. RESULTS: (1) Histological observation of the experimental sample revealed the sequence of cellular response characterized by an initial degeneration of PDL followed by a proliferation of granulation tissue. There was also a marked odontoblastic reaction with extensive deposition of regular dentine within the pulp chambers. In the control group, initial signs of bony fusion with dentine led to an extensive ankylosis and bone replacement between roots and defects. (2) Immunostaining indicated that, in experimental groups, the pattern of regularly spaced epithelial cells lying in close approximation to the root surface was distinct 10 days post-transplantation but became diminished afterwards. The immunoreaction against epithelial cells was negative in the control. CONCLUSION: Residual PDL is essential to prevent ankylosis after trauma and epithelial cells may facilitate the re-establishment of root-PDL-bone complex by transforming into mesenchymal cells.

Animals↗
PubMed2006

Design, synthesis, and structure--activity relationships for chimeric inhibitors of Hsp90.

Inhibition of the 90 kDa heat shock protein (Hsp90) family of molecular chaperones represents a promising new chemotherapeutic approach toward the treatment of several cancers. Previous studies have demonstrated that the natural products, radicicol and geldanamycin, are potent inhibitors of the Hsp90 N-terminal ATP binding site. The cocrystal structures of these molecules bound to Hsp90 have been determined, and through molecular modeling and superimposition of these ligands, hybrids of radicicol and geldanamycin have been designed. A series of macrocylic chimeras of radicicol and geldanamycin and the corresponding seco-agents have been prepared and evaluated for both antiproliferative activity and their ability to induce Hsp90-dependent client protein degradation.

Antineoplastic Agents↗
PubMed2006

Charging behavior of single-stranded DNA polyelectrolyte brushes.

DNA monolayers are widely used in fundamental and applied genomics and are versatile experimental models for elucidating the behavior of charged polymers at interfaces. The physical behavior of these systems is to a large extent governed by their internal ionic microenvironment, which is investigated here for layers of end-tethered, single-stranded DNA oligonucleotides (DNA brushes). Retention of counterions by the DNA brush manifests as lowered susceptibility of the interfacial capacitance to external salt conditions. A physical model based on concepts adapted from polymer science was used to further elucidate the connection between monolayer organization and its charging behavior. The data indicate a reorganization of the monolayer with changes in ionic strength and strand coverage that is consistent with that expected for a polyelectrolyte brush. A method for electrochemical quantification of strand coverage, based on shift of reduction potential for redox counterions associated with the DNA monolayer, is also described. These results provide guidance for development of label-free electrochemical diagnostics employing DNA monolayers and formulate a description of monolayer behavior within a polymer science framework.

DNA, Single-Stranded↗
PubMed2006

Design and synthesis of substrate and intermediate analogue inhibitors of S-ribosylhomocysteinase.

S-Ribosylhomocysteinase (LuxS) catalyzes the cleavage of the thioether linkage in S-ribosylhomocysteine (SRH) to produce homocysteine and 4,5-dihydroxy-2,3-pentanedione, the precursor of autoinducer 2. Inhibitors of LuxS should interfere with bacterial interspecies communication and potentially provide a novel class of antibacterial agents. LuxS utilizes a divalent metal ion as a Lewis acid during catalysis. In this work, a series of structural analogues of the substrate SRH and a 2-ketone intermediate were designed and synthesized. Kinetic studies indicate that the compounds act as reversible, competitive inhibitors against LuxS, with the most potent inhibitors having K(I) values in the submicromolar range. These represent the most potent LuxS inhibitors that have been reported to date. Cocrystal structures of LuxS bound with two of the inhibitors largely confirmed the design principles, i.e., the importance of both the homocysteine and ribose moieties in high-affinity binding to the LuxS active site.

Amides↗
PubMed2006

Expression of type X collagen and capillary endothelium in condylar cartilage during osteogenic transition--a comparison between adaptive remodelling and natural growth.

Adaptive remodelling of the condylar cartilage in response to mandibular protrusion constitutes the rationale for bite-jumping appliances to solicit growth modification. By investigating the expression of type X collagen and capillary endothelium, this study was designed to evaluate the osteogenic transition of chondrogenesis during adaptive remodelling of condylar cartilage and compare it with that under natural condylar growth. One hundred female Sprague-Dawley rats, 35 days of age, were divided into five experimental groups (n = 15, fitted with bite-jumping appliances) where condylar adaptation was created by forward repositioning of the mandible, and five control groups (n = 5) where the condyles underwent natural growth. The animals were sacrificed at 3, 7, 14, 21 and 30 days and 7 mum serial sections of the condyles were processed for in situ hybridization and immunohistochemical analyses. The expression of type X collagen in the hypertrophic zone and capillary endothelium in the erosive zone of condylar cartilage were examined to evaluate osteogenic transition, a critical programme leading to endochondral ossification. The results showed that (1) The temporal pattern of the expression of type X collagen and capillary endothelium during condylar adaptation coincided with that during natural condylar growth. (2) The amount of the expression of these two factors during condylar adaptation was significantly higher than that during natural growth (P < 0.001). It is suggested that condylar adaptation in growing rats triggered by mandibular forward positioning enhances osteogenic transition which eventually results in increased bone formation.

Animals↗
PubMed2006

Radanamycin, a macrocyclic chimera of radicicol and geldanamycin.

Radicicol and geldanamycin are potent inhibitors of the Hsp90 protein folding machinery, which is an emerging target for the development of cancer chemotherapeutics. However, radicicol is inactive in vivo and geldanamycin suffers from its redox-active behavior that produces toxicity unrelated to Hsp90 inhibition. It was proposed that a chimeric molecule containing the resorcinol ring of radicicol and the quinone of geldanamycin could provide an opportunity to elucidate structure-activity relationships for both natural products and serve as a starting point for the development of more potent inhibitors. Synthesis of the macrocyclic chimera named radanamycin is reported along with the biological activity exhibited by this compound in MCF-7 breast cancer cells.

Benzoquinones↗
PubMed2006

[The level of Bcl-2 and Fas expression in thymoma tissue from patients with myasthenia gravis].

OBJECTIVE: To evaluate the clinical significance of expression levels of apoptosis-associated genes, bcl-2 and Fas in thymoma tissue from patients with myasthenia gravis. METHODS: The study included 25 patients who underwent maximal thymectomy because of concurrent thymoma and myasthenia gravis. Clinical staging (Osserman classification) showed stage I in 6, IIA in 3, IIB in 13 and III in 3 cases. According to the WHO classification of thymomas (1999), 5, 3, 7, 7, and 3 patients had type A, AB, B1, B2, and B3, respectively, and no patient had type C. As a control group, the normal thymic tissue from 25 patients with congenital heart diseases was studied. The expression level of Bcl-2 and Fas in the tissue of thymoma and normal thymus was detected by immunohistochemistry. RESULTS: Bcl-2 and Fas expressions were significantly higher in thymomas compared with normal thymus by Radit analyses (U = 2.645, P < 0.05 and U = 3.200, P < 0.05, respectively). The expression level of Bcl-2 and Fas showed no relation to the course of the disease, age, Osserman classification and sex. CONCLUSION: The result suggests that the two apoptosis-associated factors, Bcl-2 and Fas, may play important roles in the pathogenesis of thymoma concurrent with myasthenia gravis.

Adult↗
PubMed2006

[The preliminary study of the treatment timing for rapid maxillary expansion].

PURPOSE: The aim of this study was to find the treatment timing of rapid maxillary expansion by investigating the relationship among the chronologic age, dental age, skeletal age and treatment effect of rapid maxillary expansion. METHODS: A sample of thirty patients who required rapid maxillary expansion was selected. The patients ranged in age from 11 to 14 years, with the mean age being 12.30 years. Assessment of the skeletal age was made with a hand radiograph before treatment. The posteroanterior cephalograms, occlusal radiograph of the maxilla were taken at the time of pretreatment and post-treatment. Paired t test and multiple regression analysis were used for statistical analysis. RESULTS: The results showed that the effects of rapid maxillary expansion were different even though the chronologic ages were similar. A negative correlation was found between the skeletal age and the expansive effect. Regressive coefficient was -6.440, P value was 0.045. There was a significant negative correlation between the dental age and the expansive effect. The regressive coefficient was -1.289, P value was 0.000. The expansive effect was on the decrease while the second maxillary molars erupted continuously. CONCLUSION: It is proposed that rapid maxillary expansion could be used successfully before the second maxillary molars erupt. The optimal orthopedic effect could be attained.

Adolescent↗
PubMed2005

Mechanism of triptolide-induced apoptosis: Effect on caspase activation and Bid cleavage and essentiality of the hydroxyl group of triptolide.

Triptolide is a compound extracted from the Chinese herb Tripterygium wilfordii Hook. f. Triptolide has potent anticancer activity. However, the mechanisms by which triptolide exerts its anticancer activities remain unclear. To explore the molecular mechanisms involved in the anticancer activity of triptolide, we have examined the effect of triptolide on the growth of pancreatic carcinoma PANC-1 and cervical adenocarcinoma HeLa cells. We found that treatment of both HeLa and PANC-1 cells with triptolide potently suppressed cell growth and induced apoptosis, indicated by nuclear fragmentation and blebbing. In both HeLa and PANC-1 cells, apoptosis induced by triptolide was associated with activation of both caspase-3 and caspase-8, and cleavage of poly(ADP-ribose) polymerase and Bid. Moreover, in HeLa cells, caspase-9 is also significantly activated in response to triptolide. Overexpression of Bcl-2 in HeLa cells substantially attenuated triptolide-induced apoptosis. Interestingly, substitution of the 14-OH of triptolide with an acetyl group abrogated both its anticancer and its antiinflammatory activities. Our studies suggest that triptolide may exert its anticancer effects by initiating apoptosis through both death-receptor- and mitochondria-mediated pathways. Our results indicate that both the apoptosis-promoting and the antiinflammatory activities of triptolide depend on the 14-OH group.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Forward deviation of the mandibular condyle enhances endochondral ossification of condylar cartilage indicated by increased expression of type X collagen.

OBJECTIVE: Using type X collagen as a marker, this research was designed to examine the alteration of condylar growth in response to mandibular condylar forward positioning. METHODS: One hundred female Sprague-Dawley rats with 5 weeks of age were randomly divided into five experimental and five control groups. In the experimental groups, bite jumping appliances created forward positioning of the condyle. The experimental rats, together with the age-matched controls, were sacrificed on days 3, 7, 14, 21 and 30, respectively. Tissue sections were cut in the sagittal plane through the mandibular condyle and were processed for in situ hybridization and immunostaining of type X collagen and then for quantitative imaging analyses. RESULTS: (1) Both type X collagen mRNA in situ hybridization signals and type X collagen immunostaining were localized within the hypertrophic zone of the condylar cartilage. (2) With condylar forward positioning, the level of type X collagen mRNA signals (8,541 +/- 74 microm(2) at peak) was 300% higher than that in the controls (2,117 +/- 78 microm(2) at peak); type X collagen immunostaining in condylar advancing groups (54,864 +/- 134 microm(2) at peak) was 254% more than that in the controls (15,470 +/- 121 microm(2) at peak). (3) The amount of type X collagen mRNA signals and immunostaining in experimental and control groups reached the highest levels at day 14 and day 21, respectively, indicating that an increase in endochondral ossification occurred 21 days after condylar forward deviation. CONCLUSION: Condylar forward repositioning provokes an enhanced maturation of condylar chondrocytes resulting in increased synthesis of type X collagen, a extracellular protein that attributes to endochondral ossification.

Animals↗
PubMed2005

Hsp90 inhibitors identified from a library of novobiocin analogues.

Novobiocin is a C-terminal inhibitor of the Hsp90 protein folding machinery, which is responsible for the conformational maturation of numerous proteins involved in cancer growth and survival. Due to novobiocin's poor inhibitory activity ( approximately 700 muM), very little attention has been paid toward the development of novobiocin analogues for Hsp90 inhibition. In this study, a parallel library of 20 novobiocin derivatives was prepared and the biological activity of each evaluated by Western blot analysis of Hsp90 client proteins. A4 was found to be a potent inhibitor of Hsp90 as determined by its ability to cause the degradation of several Hsp90 client proteins in both breast and prostate cancer cell lines. In the presence of 1 muM A4, several Hsp90 client proteins were degraded, including AKT, Her2, Hif-1alpha, and the androgen receptor.

Cell Line, Tumor↗
PubMed2005

Sensitive, label-free DNA diagnostics based on near-field microwave imaging.

Biological assays often rely on "reporter labels" to enhance measurement sensitivity, for example, by incorporation of a fluorescent dye or a nanoparticle into a nucleic acid or a protein. Use of labels, however, complicates sample preparation, increases assay costs, and can cause experimental artifacts by interfering with assay thermodynamics or limiting label stability. We evaluate near-field microwave imaging (NFMI) as an alternative, label-free technique for molecular diagnostics. Using DNA monolayers as an experimental model, NFMI is demonstrated to achieve sensitivities comparable to conventional fluorescence bioassays. Moreover, NFMI is shown to be compatible with imaging at resolutions required by microarray applications, as demonstrated by monitoring DNA hybridization in an array format.

DNA↗
PubMed2005

Radester, a novel inhibitor of the Hsp90 protein folding machinery.

[reaction: see text]. The antitumor antibiotics radicicol and geldanamycin are potent inhibitors of the Hsp90 protein folding machinery. Radester is a hybrid composed of radicicol's resorcinol ring and geldanamycin's quinone through an isopropyl ester. Radester was prepared, and the cytotoxicity of it and the corresponding hydroquinone were determined in MCF-7 breast cancer cells to be 13.9 and 7.1 microM, respectively. Protein degradation assays were performed on Hsp90-dependent client proteins, Her-2 and Raf, to correlate Hsp90 inhibition to cytotoxicity.

Antineoplastic Agents↗
PubMed2005

[Timing of treatment with bite-jumping appliance in orthodontics].

Bite-jumping appliance is a rational appliance for patients with severe overjet and retrusive mandible. In the pubertal growth spurt of patient, the appliance has good effect on skeletal or dental Angle class II malocclusions. After functional treatment, the probability of orthodontic treatment and orthopedic surgery in adult can be reduced. However, the most suitable time to use the bite-jumping appliance has been discussed continuously in various studies. According to many studies related, this paper summarized the treatment time of the fixed and the removable bite-jumping appliances, and compared the advantages and disadvantages between them.

Adult↗