[Identification model of tooth number abnormalities on pediatric panoramic radiographs based on deep learning]

Objective: To identify tooth number abnormalities on pediatric panoramic radiographs based on deep learning. Methods: Eight hundred panoramic radiographs of children aged 4 to 11 years meeting the inclusion and exclusion criteria were selected and randomly assigned by writing programs in Python (version 3.9) to the training set (480 images), verification set (160 images) and internal test set (160 images), taken in Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology between November 2012 to August 2020. And all panoramic radiographs of children aged 4 to 11 years taken in the First Outpatient Department of Peking University School and Hospital of Stomatology from June 2022 to December 2022 were collected as the external test set (907 images). All of the 1 707 images were obtained by operators to determine the outline and to label the tooth position of each deciduous tooth, permanent tooth, permanent tooth germ and additional tooth. The deep learning model with ResNet-50 as the backbone network was trained on the training set, validated on the verification set, tested on the internal test set and external test set. The images of test sets were divided into two categories according to whether there was abnormality of tooth number, to calculate sensitivity, specificity, positive predictive value and negative predictive value, and then divided into four types of extra teeth and missing permanent teeth both existed, extra teeth existed only, missing permanent teeth existed only, and normal teeth number, to calculate Kappa values. Results: The sensitivity, specificity, positive predictive value and negative predictive value were 98.0%, 98.3%, 99.0% and 96.7% in the internal test set, and 97.1%, 98.4%, 91.9% and 99.5% in the external test set respectively, according to whether there was abnormality of tooth number. While images were divided into four types, the Kappa value obtained in the internal test set was 0.886, and that in the external test set was 0.912. Conclusions: In this study, a deep learning-based model for identifying abnormal tooth number of children was developed, which could identify the position of additional teeth and output the position of missing permanent teeth on the basis of identifying normal deciduous and permanent teeth and permanent tooth germs on panoramic radiographs, so as to assist in diagnosing tooth number abnormalities.

[Whole exome sequencing and analysis of hypohidrotic ectodermal dysplasia patients]

Objective: To detect gene mutation in patients with hypohidrotic ectodermal dysplasia (HED) by using whole exome sequencing, to analyze the pathogenicity of the mutations, and to provide reference for the genetic diagnosis of HED patients. Methods: Peripheral blood genomic DNA was extracted from each of the HED patients and their family members collected in Peking University School and Hospital of Stomatology from August 2016 to August 2021. Whole exome sequencing and sanger sequencing were performed to detect gene mutations. Functions of the rare variants after the database filtering were analyzed by bioinformatics tools. Results: Three reported mutations of ectodysplasin A (EDA) gene (c.2T>C, c.161A>G, c.467G>A) and a mutation of ectodysplasin A receptor (EDAR) gene (c.871G>A) were detected by whole genome sequencing in four HED patients, and were verified by Sanger sequencing in four HED families. The EDAR gene mutation founded in this research was reported in HED patients for the first time. Bioinformatics tools predicted that the mutations of EDA gene detected in this study were highly species conserved and disease-causing. The combined annotation dependent depletion (CADD) scores of EDA gene mutations c.2T>C, c.161A>G and c.467G>A were 22.5, 26.3 and 25.5 respectively, and the genomic evolutionary rate profiling (GERP) scores were 2.16, 2.26 and 2.18 respectively. The EDAR gene mutation c.871G>A detected in this study was species conserved and possibly disease-causing. The CADD and GERP scores of EDAR gene mutation c.871G>A were 22.0 and 1.93 respectively. Conclusions: Three reported mutations of EDA gene and a previously unreported mutation of EDAR gene were detected in four HED families. Different mutations of EDA gene and EDAR gene could make different influence on the protein function and lead to the occurrence of HED.

[Development of a deep learning based prototype artificial intelligence system for the detection of dental caries in children]

Objective: To develop a prototype artificial intelligence image recognition system for detecting dental caries, especially those without cavities, in children. Methods: Seven hundred and twelve intraoral photos, which were taken by dental professionals using a digital camera from October 2013 to June 2020 in the Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, were collected from the children who received dental treatment under general anesthesia. The well-documented post-treatment electronic dental record of each child was identified as label standard to determine whether the teeth were carious and the type of caries types such as caries that had become cavities (caries with cavities), pit and fissure caries that had not become cavities (pit and fissure caries) and proximal caries which the marginal ridge enamel had not been destroyed (proximal caries). The various teeth and caries types were labeled by pediatric dentists using VoTT software (Windows 2.1.0, Microsoft, U S A). There were five labeled groups: pit and fissure caries, approximal caries, non-carious approximal surfaces, caries with cavities and teeth without caries (including intact fillings). Each group was randomly divided into training dataset, validation dataset and test dataset at a ratio of 6.4∶1.6∶2.0 by using random number table. After using the labeled training dataset for deep learning training, a deep learning-based artificial intelligence (AI) image recognition system for detecting dental caries was established, with the caries probability greater than 50.0% as the criterion for determining caries. Sensitivity and accuracy were used as indicators of recognition specificity. Results: Seven hundred and twelve single-jaw intraoral photographs were segmented and annotated into 953 pit and fissure caries, 1 002 approximal caries, 3 008 caries with cavities, 3 189 teeth without caries and 862 non-carious approximal surfaces, totaly 9 014 labels. The sensitivities and specificities of the test set were 96.0% and 97.0% for caries with cavities, 95.8% and 99.0% for pit and fissure caries and 88.1% and 97.1% for approximal caries. Conclusions: The current AI system developed based on deep learning of the intra-oral photos in the present study showed the ability to detect dental caries. Furthermore, the AI system could accurately verify different types of dental caries such as caries with cavities, pit and fissure caries and proximal caries.

[Clinical analysis of 16 cases of pulmonary epithelioid hemangioendothelioma]

Objective: To improve the diagnosis and treatment of pulmonary epithelioid hemangioendothelioma (P-EHE). Methods: Sixteen patients diagnosed with P-EHE in Fuzhou Pulmonary Hospital of Fujian Province from January 2009 to July 2020 were collected. Their gender, age, imaging findings, pathological characteristics, treatment protocols, survival and other clinical data were summarized and analyzed. Results: The ratio of male to female among the 16 patients was 1∶1; and the average age of onset was 47.75 years. Most cases of PEHE (9/16) were found by physical examination, while some cases developed respiratory symptoms such as cough, sputum, shortness of breath, hemoptysis, chest pain, etc. (7/16). In most patients the lesions were localized to the lungs (11/16), while bone metastasis (1/16), lymph node metastasis (1/16), and pleural metastasis (4/16) also occurred. The pathological tissues were obtained mainly through surgical thoracoscopy. Chest CT images showed multiple nodules in both lungs, with most of the nodules less than 2.0 cm in diameter, and calcifications were seen, while solitary nodules and masses were rare, and pleural metastases could be manifested as pleural thickening and pleural effusion. The pathological findings were well-defined eosinophilic nodules with irregularly arranged nest-like structures. Those eosinophilic nodules had few central cells and abundant peripheral cells, which extended into the alveolar cavity like papillae. The tumor cells were epithelioid with small atypia, and vacuoles and red blood cells could be seen in the cytoplasm of individual tumor cells. Immunohistochemically, the tumor cells were positive to CD34, CD31, Factor Ⅷ andvimentin (VIM). Follow-up of 0.5 to 11 years showed that four patients died, two lost to follow-up, and the rest of the patients were in good condition, with a median overall survival (OS) of 4.58 years. Conclusions: PEHE is a rare low-grade lung tumor with no specific clinical manifestations. It can be diagnosed with chest imaging and pathological immunohistochemistry. Moreover, there is currently no standard treatment for PEHE, and most patients have a good prognosis.

Simultaneous multi-slice accelerated diffusion-weighted imaging with higher spatial resolution for patients with liver metastases from neuroendocrine tumours

AIM

To evaluate the imaging characteristics of simultaneous multi-slice (SMS) accelerated diffusion-weighted imaging (DWI) with decreased section thickness, with and without motion correction, in comparison to conventional DWI (cDWI) for the detection of lesions in patients with neuroendocrine tumour (NET) liver metastases.

MATERIALS AND METHODS

Fifteen patients with NET liver metastases underwent cDWI (section thickness [SL]=4 mm) and SMS-DWI (SL=2 mm). Non-linear motion-corrected (Moco)-SMS-DWI was generated in addition to the original series. Qualitative imaging characteristics (five-point Likert scale), the number of high signal lesions, and the detectability and delineation of lesions were evaluated and compared using the Friedman and the Dunn-Bonferroni tests. The test-retest variability (TRV) of the cDWI and SMS-DWI techniques was investigated among 11 healthy volunteers who underwent cDWI (SL=4 mm) and SMS-DWI (SL=4 mm) twice. The Friedman and the Dunn-Bonferroni post-hoc tests were used to compare the mean apparent diffusion coefficient (ADC) and the TRV in different liver regions between the three series.

RESULTS

Moco-SMS-DWI demonstrated significantly superior overall image quality (p<0.001) with significantly fewer artefacts (p=0.003) than cDWI. The number of lesions detected by cDWI, SMS-DWI, and Moco-SMS-DWI were 348, 504, and 523, respectively. The detectability and delineation of the lesions and the ADC values were significantly higher on the SMS-DWI and Moco-SMS-DWI images than on the cDWI images (all p<0.001). Moco-SMS-DWI showed significantly higher TRV than cDWI in regions near the liver edge (p=0.018).

CONCLUSIONS

SMS-DWI achieves higher spatial resolution than cDWI within the same acquisition time, detects more lesions, and provides better lesion delineation. By applying motion correction, the TRV of DWI could be enhanced in regions near the liver edge.

Erythropoietin attenuates vascular calcification by inhibiting endoplasmic reticulum stress in rats with chronic kidney disease

Previous studies suggested that endoplasmic reticulum (ER) stress induced-apoptosis promoted vascular calcification (VC). Interestingly, erythropoietin (EPO), an endogenous glycoprotein, exerts multiple tissue protective effects by inhibiting ER stress and apoptosis. We investigated the role and potential mechanism of EPO on VC in chronic kidney disease (CKD) rats and cultured vascular smooth muscle cells (VSMCs). The calcification model was established by subtotal nephrectomy in vivo or phosphate overload in vitro. The protein level of EPO receptor (EPOR) was increased in the calcified aortas of CKD rats. EPO prevented the reduction of VSMC phenotypic markers, and reversed the increased calcium content and calcium salt deposition in the aortas of CKD rats and cultured calcified VSMCs. The protein levels of activating transcription factor 4 (ATF4) and glucose-regulated protein 94 (GRP94) were upregulated in aortas and VSMCs under calcifying conditions, indicating ER stress activation. EPO treatment of CKD rats or calcified VSMCs downregulated the protein levels of ATF4 and GRP94. Furthermore, ER stress-mediated apoptosis, determined by the protein levels of CCAAT⁄enhancer-binding protein-homologous protein and cleaved caspase 12, was increased in tunicamycin or calcification media-treated VSMCs, but the increased effect was reversed in EPO-treated groups. The increased apoptotic cells in calcified VSMCs, as indicated by Hoechst staining and flow cytometry, were downregulated by the co-administration of EPO or 4-phenyl butyric acid. In conclusion, EPO might attenuate VC by inhibiting ER stress mediated apoptosis through EPOR signaling.

Lipopolysaccharide inhibits GPR120 expression in macrophages via Toll-like receptor 4 and p38 MAPK activation

Free fatty acid receptor G protein-coupled receptor 120 (GPR120) is highly expressed in macrophages and was reported to inhibit lipopolysaccharide (LPS)-stimulated cytokine expression. Under inflammation, macrophages exhibit striking functional changes, but changes in GPR120 expression and signaling are not known. In this study, the effects of LPS treatment on macrophage GPR120 expression and activation were investigated. The results showed that LPS inhibited GPR120 expression in mouse macrophage cell line Ana-1 cells. Moreover, LPS treatment inhibited GPR120 expression in mouse alveolar macrophages both in vitro and in vivo. The inhibitory effect of LPS on GPR120 expression was blocked by Toll-like receptor 4 (TLR4) inhibitor TAK242 and p38 mitogen-activated protein kinase inhibitor LY222820, but not by ERK1/2 inhibitor U0126 and c-Jun N-terminal kinase inhibitor SP600125. LPS-induced inhibition of GPR120 expression was not attenuated by GPR120 agonists TUG891 and GW9508. TUG891 inhibited the phagocytosis of alveolar macrophages, and LPS treatment counteracted the effects of TUG891 on phagocytosis. These results indicate that pretreatment with LPS inhibits GPR120 expression and activation in macrophages. It is suggested that LPS-induced inhibition of GPR120 expression is a reaction enhancing the LPS-induced pro-inflammatory response of macrophages.

[Clinical analysis of laryngeal non-Hodgkin's lymphoma]

Objective:To analyze the clinical characteristics, pathology and treatment of laryngeal non-Hodgkin's lymphoma.Method:Clinical information of 31 patients with laryngeal non-Hodgkin's lymphoma treated in our hospital was reviewed retrospectively. Result:T cell lymphoma, B cell lymphoma, NK/T cell lymphoma, the mixed pattern and unspecified lymphoma accounted for 16.1%(5/31),32.3%(10/31),35.5%(11/31)and 16.1%(5/31) of the patients, respectively.Twenty-seven cases were located in supraglottic region, 1 case was located in glottic region, and 3 cases were located in glottic and subglottic region. Conclusion:The laryngeal non-Hodgkin's lymphoma was a rare malignant neoplasm and the most localized in the supraglottic region.Its diagnosis depended on comprehensive immunohistochemistry examination.Chemotherapy and radiotherapy were the main therapeutic methods.

[Clinical study on autologus platelet-rich fibrin aided revascularization of immature permanent teeth]

OBJECTIVE

To compare the clinical treatment efficiency of platelet-rich fibrin (PRF) assisted revascularization and traditional revascularization in immature permanent teeth.

METHODS

Eighteen non-vital immature permanent teeth of sixteen patients which were diagnosed as necrotic pulpitis with (or without) periapical inflammations were treated with PRF assisted revascularization. Twenty-two teeth non-vital immature permanent teeth of twenty patients which were diagnosed as necrotic pulpitis with (or without) periapical inflammations were treated with traditional revascularization. All the cases were accorded with inclusive criteria and were treated at Pediatric Dentistry of Peking University School and Hospital of Stomatology. The cases were followed up clinically and radiographically at regular intervals. Clinical examinations and periapical radiographs were recorded and analyzed. Clinical success rate was evaluated based on the clinical and radiographic findings. The changes of root length, dentine wall thickness and apical foramen width of the teeth from the two groups were measured and compared according to the preoperative and by recalling the periapical radiographs.

RESULTS

The cases were followed up for 6-16 months. Clinically, totally 17 out of the 18 teeth in PRF group and 21 out of the 22 teeth in traditional group were asymptomatic with no sensitivity to percussion or palpation. PRF group tended to be more effective than traditional group clinically without significant differences (P=0.446). Radiographically, 15 out of the 18 teeth in PRF group and 15 out of the 22 teeth in traditional group displayed that the roots developed, showing that root length and dentine wall thickness increased and apical foramen closed. There was a marked difference in dentine wall thickening in PRF group in comparison with traditional group (P=0.039). However, the changes of root length increasing (P=0.411) and apical foramen width closure (P=0.737) were comparable in both groups. The result in electric pulp test (P=0.517), root canal calcification (P=0.324) and crown discolor (P=0.386) were also comparable in the two groups.

CONCLUSION

PRF assisted revascularization and traditional revascularization in non-vital immature permanent teeth which were diagnosed as necrotic pulpitis with (or without) periapical inflammations resulted in similar clinical outcomes. Both methods showed good prognosis. PRF revascularization seemed to have better effect on dentine wall thickening than traditional method.

[Capsaicin Alleviate Myocardial Ischemia Reperfusion Injury Through Attenuating Mitochondrial Oxidative Stress]

OBJECTIVE

To investigate the role of capsaicin (CAP) in myocardial ischemia reperfusion injury and its underlying mechanisms.

METHODS

Twentyfour adult male SD rats were randomized into 4 groups,namely the control group,ischemia reperfusion group,ischemia reperfusion with CAP group,and ischemia reperfusion with CAPZ and CAP group. Isolated rat hearts underwent Langendorff perfusion. Left ventricular enddiastolic pressure (LVEDP) andleft ventricular developed pressure (LVDP) was calculated to evaluate myocardial performance at 30 min of reperfusion.Triphenyltetrazolium chloride staining was used to measure the infarct size of myocardium at 120 min reperfusion. The morphological changes in myocardial fiber was analyzed by HE staining at the end of reperfusion. Lactate dehydrogenase (LDH) content in the coronary flow was determined during the first 5 min reperfusion. The myocardial mitochondria was isolated and extracted for measuring a series of indicators of mitochondrial oxidative stress,including superoxide dismutase (SOD),methane dicarboxylic aldehyde (MDA) at the end of reperfusion. Western blot was used to determine the expression of caspase3 and cytochrome c at 10 min reperfusion.

RESULTS

Compared with the control group,IR group significantly decreased in cardiac function,the level of LVDP and SOD activity and induced an enlarged infarct size ( P<0.01),accompanied by the disordered arrangement of myocardial cells,the content of MDA was increased ( P<0.01),the content of caspase3 and cytochrome c were also upregulated ( P<0.01).10 μmol/L CAP significantly attenuated these effects induced by ischemia reperfusion injury,levels of LVDP and infarct size at the end of reperfusion were significantly improved( P<0.01),nevertheless levels of LVEDP and MDA at the end of reperfusion and LDH were down-regulated markedly ( P<0.01),the content of caspase-3 and cytochrome c were also decreased ( P<0.01).

CONCLUSION

These results demonstrate that CAP can suppresses cell apoptosis and necrosis,and alleviate heart function and cell survival from ischemia reperfusion injury through attenuating mitochondrial oxidative stress.

[Effect of inhibiting perivascular adhesion on intimal hyperplasia of the vein grafts in rabbits]

Objective: To investigate the effect of preventing perivascular adhesion with topical application of sodium hyaluronate on intimal hyperplasia of the vein grafts in rabbits. Methods: Twenty-four male New Zealand white rabbits, aged 5 months, were randomly divided into 2 groups: Group A and B (n=12 rabbits per group). Artery defect model was established by cutting about 1 cm artery from the middle part of the dissociated left common carotid artery. A section about 3 cm was cut from the right external jugular vein, and the harvested vein was inverted and end-to-end anastomosed to the artery defect. After anastomosis, the adventitia and two anastomosis of the grafted veins in group A was applied 0.2 ml sodium hyaluronate locally to, and corresponding site in Group B was served as a control, but with the sterile normal saline. The grafted veins were obtained 1, 2 and 4 weeks after operation, HE staining and Masson staining were preformed for histological changes of grafted vein wall, proliferating cell nuclear antigen (PCNA) and platelet-derived growth factor (PDGF) immunohistochemistry staining were conducted for proliferation and expression and distribution of PDGF of the grafted vein. Results: The macroscopic and histological observation showed that the perivascular adhesions in Group A were looser when compared with those in Group B. The thickness of the intima, the degree of intima hyperplasia of 2 groups at different time points were as follows: at 1 week after operation, group A[(25.5±3.9) μm, (1.2±0.1) ]and group B[(26.2±4.2)μm, (1.2±0.1)]; at 2 weeks after operation, group A[(44.3±2.5)μm, (1.2±0.1)]and group B[(51.0±3.8)μm, (1.4±0.0)]; at 4 weeks after operation, group A[(69.9±6.8)μm, (1.5±0.1)] and group B[(84.4±6.4)μm, (1.7±0.1)]. Group A was inferior to group B in terms of the above three parameters 2 and 4weeks after operation (P<0.05). Cell proliferation index of intima and that of media were as follows: at 1 week after operation, group A (7.4±2.2), (21.5±3.2) and group B (11.5±2.0), (28.6±4.5); at 2 weeks, group A (20.0±3.2), (35.8±3.4) and group B (26.8±4.1), ( 42.6±4.2); at 4 weeks, group A (11.4±2.0), (22.1±2.7) and group B (15.5±2.4, 28.6±3.9). Group A was inferior to group B in terms of cell proliferation index of intima and media 1, 2 and 4 weeks after operation (P<0.05). The percentage of PDGF-positive cells of intima, media and adventitia was as follows: at 1 week after operation, group A (7.7±1.6), (19.6±3.7), (2.5±1.5) and group B (7.6±2.4), (20.6±4.4), (10.3±2.3); at 2 weeks after operation, group A (11.4±2.6), (19.8±3.1), (12.9±3.3) and group B (19.5±3.5), ( 30.6±5.2), (30.5±5.8); at 4 weeks after operation, group A (6.2±1.9), ( 11.1±2.8), (10.2±2.4) and group B (10.5±2.0), (18.6±3.2), (26.5±3.8). Group A was inferior to group B in terms of the percentage of PDGF-positive cells of intima, media and adventitia 2 and 4 weeks after operation (P<0.05) and Group A was inferior to group B that of adventitia 1 week after operation (P<0.05). Conclusion: Preventing perivascular adhesion with topical application of sodium hyaluronate can inhibit intimal hyperplasia.

[Carpal canal ultrasound examination in patients with mild hand-arm vibration disease]

Objective: To investigate the clinical value of ultrasound examination of carpal canal structure in patients with mild hand-arm vibration disease. Methods: A total of 29 patients (58 wrists) with mild hand-arm vibration disease who were treated in Shenzhen Prevention and Treatment Center for Occupational Diseases from May to December, 2015 were enrolled as observation group, and 20 healthy volunteers (40 wrists) were enrolled as the control group. Color Doppler ultrasound was used to observe the morphology and echo of the median nerve in the carpal canal and 9 muscle tendons and transverse carpal ligament. The thickness of transverse carpal ligament and diameter of the median nerve at the level of the hamulus of hamate bone were measured, as well as the cross-sectional area of the median nerve at the level of pisiform bone. Results: In the 29 patients with hand-arm vibration disease patients in the observation group, 8 experienced entrapment of the median nerve in the carpal canal, among whom 5 had entrapment in both wrists; there were 13 wrists (23%) with nerve entrapment and 45 wrists (77%) without nerve entrapment. Compared with the control group, the patients with hand-arm vibration disease and nerve entrapment in the observation group showed significant thickening of the transverse carpal ligament at the level of the hamulus of hamate bone and a significant increase in the cross-sectional area of the median nerve at the level of pisiform bone (P<0.05) , while there were no significant differences in the thickness of transverse carpal ligament at the level of the hamulus of hamate bone and the cross-sectional area of the median nerve at the level of pisiform bone (t=-9.397 and -4.385, both P>0.05) . Conclusion: Ultrasound examination can clearly show the radiological changes of carpal canal contents in patients with mild hand-arm vibration disease and has a certain diagnostic value in nerve damage in patients with hand-arm vibration disease.

[Effect of 2,3-butanedione monoxime on calcium paradox-induced heart injury in rats]

OBJECTIVE

To investigate the Effect of 2,3-butanedione monoxime (BDM) on calcium paradox-induced heart injury and its underlying mechanisms.

METHODS

Thirty-two adult male SD rats were randomized into 4 groups, namely the control group, BDM treatment control group, calcium paradox group, and BDM treatment group. Isolated Sprague Dawley male rat hearts underwent Langendorff perfusion and the left ventricular pressure (LVP) and left ventricular end-diastolic pressure (LVEDP) were monitored. Left ventricular developed pressure (LVDP) was calculated to evaluate the myocardial performance. Lactate dehydrogenase (LDH) content in the coronary flow was determined. Triphenyltetrazolium chloride staining was used to measure the infarct size, and myocardial cell apoptosis was tested with TUNEL method. Western blotting was used to determine the expression of cleaved caspase-3 and cytochrome c.

RESULTS

Compared with the control group, BDM at 20 mmol/L had no effect on cardiac performance, cell death, apoptotic index or the content of LDH, cleaved caspase-3 and cytochrome c at the end of perfusion under control conditions (P>0.05). Calcium paradox treatment significantly decreased the cardiac function and the level of LVDP and induced a larger infarct size (P<0.01), an increased myocardial apoptosis index (P<0.01), and up-regulated expressions of cleaved caspase-3 and cytochrome c (P<0.01). BDM (20 mmol/L) significantly attenuated these effects induced by calcium paradox, and markedly down-regulated the levels of LVEDP and LDH (P<0.01), lowered myocardial apoptosis index, decreased the content of cleaved caspase-3 and cytochrome c (P<0.01), increased LVDP, and reduced the infarct size (P<0.01).

CONCLUSION

BDM suppresses cell apoptosis and contracture and improves heart function and cell survival in rat hearts exposed to calcium paradox, suggesting the value of BDM as an potential drug for myocardial ischemia reperfusion injur.

The MBE growth and optimization of high performance terahertz frequency quantum cascade lasers

The technique of molecular beam epitaxy has recently been used to demonstrate the growth of terahertz frequency GaAs/AlGaAs quantum cascade lasers (QCL) with Watt-level optical output powers. In this paper, we discuss the critical importance of achieving accurate layer thicknesses and alloy compositions during growth, and demonstrate that precise growth control as well as run-to-run growth reproducibility is possible. We also discuss the importance of minimizing background doping level in maximizing QCL performance. By selecting high-performance active region designs, and optimizing the injection doping level and device fabrication, we demonstrate total optical (two-facet) output powers as high as 1.56 W.

An enhanced cAMP pathway is responsible for the colonic hyper-secretory response to 5-HT in acute stress rats

5-hydroxytryptamine (5-HT) is involved in the stress-induced alteration of colonic functions, specifically motility and secretion, but its precise mechanisms of regulation remain unclear. In the present study, we have investigated the effects of 5-HT on rat colonic mucosal secretion after acute water immersion restraint stress, as well as the underlying mechanism of this phenomenon, using short circuit current recording (I(SC)), real-time polymerase chain reaction, Western blot analysis, and enzyme-linked immunosorbance assays. After 2 h of water immersion restraint stress, the baseline I(SC) and 5-HT-induced I(SC) responses of the colonic mucosa were significantly increased. Pretreatment with selective 5-HT(4) receptor antagonist, SB204070, inhibited the 5-HT-induced colonic I(SC) response by 96 % in normal rats and 91.2 % in acute-stress rats. However, pretreatment with the selective antagonist of 5-HT(3) receptor, MDL72222 or Y-25130, had no obvious effect on 5-HT-induced I(SC) responses under either set of conditions. Total protein expression of both the mucosal 5-HT(3) receptors and the 5-HT(4) receptors underwent no significant changes following acute stress. Both colonic basal cAMP levels and foskolin-induced I(SC) responses were significantly enhanced in acute stress rats. 5-HT significantly enhanced the intracellular cAMP level via 5-HT(4) receptors in the colonic mucosa from both control and stressed animals, and 5-HT-induced cAMP increase in stressed rats was not more than that in control rats. Taken together, the present results indicate that acute water immersion restraint stress enhances colonic secretory responses to 5-HT in rats, a process in which increased cellular cAMP accumulation is involved.

[The role of NMDA and NK1 receptors in cardiac nociceptive information transmissions in the spinal cords of rats]

OBJECTIVE

To determine the effects of NMDA and NK1 receptor agonist and antagonist on the EMG and the synaptic mechanism of nociceptive information transmissions in the spinal cords.

METHODS

Male SD rats were randomly divided into seven groups, with intrathecal injection of the following chemicals respectively: control group (10 microL saline), NMDA group (0.147 microg/10 pL NMDA), MK801 group (6.8 microg/10 microL MK801), MK801+NMDA group (6.8 microg/10 pL MK801+0. 147 microg/10 pL NMDA), Sar-SP group (1.4 pg/10 microL Sar-SP), CP-96345 group (5 microg/10 pL CP-96345), and CP-96345+Sar-SP group (1.4 micro/10 microL Sar-SP+5 microg/10 microL CP-96345). A cardiac pain model in rats through intrapericardial injection of capsaicin was established. Intrapericardial injection of capsaicin was given to the rats 10 min after intrathecal injection of the tested chemicals. The spinotrapezius electromyography (EMG) activities as an index of cardiac-somatic motor reflex were recorded simultaneously.

RESULTS

Compared with the pre-test controls (100%), saline did not make a significant change to the capsaicin-evoked EMG response (96. 9% +/- 12. 5%, P>0. 05); NMDA agonist increased the capsaicin-evoked EMG response (185. 2% +/- 24. 4%) significantly (P<0. 05); neither MK801 nor a combined administration of MK801 and NMDA made a significant change to the capsaicin-evoked EMG response (106. 6% +/- 10. 2%, P> 0.05); Sar-SP increased the capsaicin-evoked EMG response (145. 6% 10. 1%) significantly (P<0. 05); whereas neither CP-96345 nor a combined administration of CP-96345 and Sar-SP made a significant change to the capsaicin-evoked EMG response (102. 2% +/- 8. 4%, P>0.05).

CONCLUSION

NMDA and NK1 receptors may have participated in the transmissions of cardiac nociception information in the spinal cords of rats.

The role of α₂ adrenoceptor in mediating noradrenaline action in the ventrolateral orbital cortex on allodynia following spared nerve injury

The present study examined the role of α₂ adrenoceptor in mediating noradrenaline action in the ventrolateral orbital cortex (VLO) on allodynia induced by spared nerve injury (SNI) in the rat. The mechanical paw withdrawal threshold (PWT) was measured using von-Frey filaments. Microinjection of noradrenaline (1, 2, 4 μg in 0.5 μl) into the VLO, contralateral to the site of nerve injury, reduced allodynia; PWT increased in a dose-dependent manner. Similar to noradrenaline, microinjection of selective α₂ adrenoceptor agonist clonidine into the same VLO site also reduced allodynia, and was blocked by selective α₂ adrenoceptor antagonist yohimbine. Furthermore, administration of γ-aminobutyric acid A (GABAA) receptor antagonist bicuculline or picrotoxin to the VLO significantly enhanced clonidine-induced inhibition of allodynia, while GABAA receptor agonist muscimol or THIP (2,5,6,7-retrahydroisoxazolo(5,4-c)pyridine-3-ol hydrochloride) attenuated clonidine-induced inhibition. These results suggest that noradrenaline acting in the VLO can potentially reduce allodynia induced by SNI, and this effect is mediated by α₂ adrenoceptor. Moreover, GABAergic disinhibition may participate in α₂ receptor mediating effects in neuropathic pain in the central nervous system.

Peroxide induced tin oxide coating of graphene oxide at room temperature and its application for lithium ion batteries

We describe a new, simple and low-temperature method for ultra-thin coating of graphene oxide (GO) by peroxostannate, tin oxide or a mixture of tin and tin oxide crystallites by different treatments. The technique is environmentally friendly and does not require complicated infrastructure, an autoclave or a microwave. The supported peroxostannate phase is partially converted after drying to crystalline tin oxide with average, 2.5 nm cassiterite crystals. Mild heat treatment yielded full coverage of the reduced graphene oxide by crystalline tin oxide. Extensive heat treatment in vacuum at >500 °C yielded a mixture of elemental tin and cassiterite tin oxide nanoparticles supported on reduced graphene oxide (rGO). The usefulness of the new approach was demonstrated by the preparation of two types of lithium ion anodes: tin oxide-rGO and a mixture of tin oxide and tin coated rGO composites (SnO(2)-Sn-rGO). The electrodes exhibited stable charge/discharge cyclability and high charging capacity due to the intimate contact between the conductive graphene and the very small tin oxide crystallites. The charging/discharging capacity of the anodes exceeded the theoretical capacity predicted based on tin lithiation. The tin oxide coated rGO exhibited higher charging capacity but somewhat lower stability upon extended charge/discharge cycling compared to SnO(2)-Sn-rGO.

Metabotropic glutamate subtype 7 and 8 receptors oppositely modulate cardiac nociception in the rat nucleus tractus solitarius

Recent study from our laboratory has indicated that microinjection of glutamate into the nucleus tractus solitarius (NTS) facilitates the cardiac-somatic reflex induced by pericardial capsaicin. Further, N-methyl-d-aspartate (NMDA) receptors and metabotropic glutamate receptors (mGluRs) mediate this function. However, the roles of the individual receptor subtypes or subunits in modulating cardiac nociception are unknown. Among the three groups of mGluRs, group III mGluRs are the primary mGluR subtype expressed in visceral afferent neurons in the NTS. The present study examined the roles of group III mGluRs and their subtype 7 and 8 receptors (mGluR7 and mGluR8) in modulating the cardiac-somatic reflex induced by pericardial capsaicin, which was monitored by recording electromyogram (EMG) activity from the spinotrapezius muscle in anesthetized rats. Intra-NTS microinjection of a group III mGluR agonist, l-(+)-2-Amino-4-phosphonobutyric acid (l-AP4, at 1, 10, and 20 nmol) or a selective mGluR7 agonist, N,N'-diphenylmethyl-1,2-ethanediamine dihydrochloride (AMN082, at 1, 2, and 4 nmol) both decreased the EMG response in a dose-dependent manner. This decrease was inhibited by the group III mGluR antagonist (RS)-α-Methylserine-O-phosphate (MSOP, at 20 nmol). In contrast, intra-NTS microinjection of a selective mGluR8 agonist, (S)-3, 4-dicarboxyphenylglycine (DCPG, at 6 and 8 nmol), significantly increased the EMG response above control levels. This effect was eliminated by intra-NTS MSOP and by vagal deafferentation. These data suggest that group III mGluRs and mGluR7 in the NTS display an inhibitory effect, while mGluR8 displays a facilitatory effect in modulating cardiac nociception, and this facilitatory effect is dependent on vagal afferents.

Activation of submucosal 5-HT(3) receptors elicits a somatostatin-dependent inhibition of ion secretion in rat colon

BACKGROUND AND PURPOSE

5-Hydroxytryptamine (5-HT) is a key regulator of the gastrointestinal system and we have shown that submucosal neuronal 5-HT(3) receptors exerted a novel inhibitory effect on colonic ion transport. The aim of the present study was to investigate the precise mechanism(s) underlying this inhibitory effect.

EXPERIMENTAL APPROACH

Mucosa/submucosa or mucosa-only preparations from rat distal colon were mounted in Ussing chambers for measurement of short-circuit current (I(sc)) as an indicator of ion secretion. Somatostatin release was determined with radioimmunoassay. Intracellular cAMP content was measured with enzyme-linked immunoadsorbent assay (elisa). Immunohistochemical techniques were used to study the expression of 5-HT(3) receptors, somatostatin and somatostatin receptors in colonic tissue.

KEY RESULTS

In rat distal colonic mucosa/submucosa preparations, pretreatment with 5-HT(3) receptor antagonists enhanced 5-HT-induced increases in I(sc). However, in mucosa-only preparations without retained neural elements, pretreatment with 5-HT(3) receptor antagonists inhibited 5-HT-induced DeltaI(sc). Pretreatment with a somatostatin-2 (sst(2)) receptor antagonist in mucosa/submucosa preparations augmented 5-HT-induced DeltaI(sc). Combination of sst(2) and 5-HT(3) receptor antagonists did not cause further enhancement of 5-HT-induced DeltaI(sc). Moreover, both sst(2) and 5-HT(3) receptor antagonists enhanced 5-HT-induced increase in intracellular cAMP concentration in the mucosa/submucosa preparations. 5-HT released somatostatin from rat colonic mucosa/submucosa preparations, an effect prevented by pretreatment with 5-HT(3) receptor antagonists. Immunohistochemical staining demonstrated the presence of 5-HT(3) receptors on submucosal somatostatin neurons and of sst(2) receptors on colonic mucosa.

CONCLUSION AND IMPLICATIONS

Activation of neuronal 5-HT(3) receptors in the submucosal plexus of rat colon suppressed 5-HT-induced ion secretion by releasing somatostatin from submucosal neurons.

Expression of NKCC2 in the rat gastrointestinal tract

NKCC2, an isoform of Na+-K+-2Cl(-) cotransporter, is principally present in the kidney and plays a critical role in salt reabsorption. Expression of NKCC2 has been found in the apical membrane of intestinal epithelial cells in a number of marine fish, however, details for expression in the mammalian gastrointestinal tract are lacking. RT-PCR, Western blotting and immunohistochemistry were used to study the expression and localization of NKCC2 in the rat gastrointestinal tract. We found that mRNA transcripts, protein and immunoreactivity (IR) for NKCC2 were expressed in the stomach, small and large intestine of adult rats. NKCC2 IR was localized to the base of the gastric glands, intestinal epithelia, myenteric and submucosal plexuses. NKCC2 IR was expressed strongly in the apical membranes and weakly in the basolateral membranes of intestinal epithelial cells. In the enteric nervous system, NKCC2 IR was widely distributed and localized to enteric neurons with cholinergic, calretinin and nitrergic neuronal immunochemical codes in the myenteric plexus. It was localized to non-cholinergic secretomotor neurons in the submucosal plexus. In conclusion, this study for the first time clearly detected the expression of NKCC2 in the gastrointestinal tract of a mammalian species. Expression of NKCC2 in gastrointestinal epithelial cells suggested that this cation chloride cotransporter might be involved in gastrointestinal ion transport. Expression of NKCC2 in enteric neurons might contribute to the accumulation of Cl(-) and a more depolarized E(Cl)(-) in enteric neurons.

Cooperative effects of adenoviral vector-mediated interleukin 12 gene therapy with radiotherapy in a preclinical model of metastatic prostate cancer

We investigated the potential benefits of combining adenoviral vector mediated in situ interleukin-12 (AdmIL-12) gene therapy with radiation therapy (XRT) to enhance therapeutic efficacy. In a metastatic mouse prostate cancer cell line, 178-2 BMA, AdmIL-12+XRT demonstrated enhanced therapeutic activities in vitro as determined by clonogenic survival, apoptosis, and mIL-12 levels. At the molecular level, increased expression of tumor necrosis factor-alpha mRNA was specific for the combined therapy. In a subcutaneous 178-2 BMA in vivo model, the combination of AdmIL-12+XRT produced statistically significant tumor growth suppression compared to control vector Adbetagal, Adbetagal XRT, or AdmIL-12 as monotherapy. In addition, significant prolongation of survival was demonstrated for the combination of AdmIL-12+XRT. The combination of AdmIL-12+XRT significantly suppressed both spontaneous and pre-established lung metastases, and led to a prolonged elevation of serum IL-12 and significantly increased natural killer (NK) activities. Importantly, in vivo depletion of NK cells resulted in significant attenuation of the antimetastatic activities of AdmIL-12 alone or AdmIL-12+XRT. These combined effects suggest that AdIL-12 gene therapy together with radiotherapy may achieve maximal tumor control (both local and systemic) in selected prostate cancer patients via radio-gene therapy induced local cytotoxicity and local and systemic antitumor immunity.

Effects of cassia oil on serum and hepatic uric acid levels in oxonate-induced mice and xanthine dehydrogenase and xanthine oxidase activities in mouse liver

We investigated the hypouricemic effects of cassia oil extracted from Cinnamomum cassia using hyperuricemic mice induced by potassium oxonate, and its inhibitory actions against liver xanthine dehydrogenase (XDH) and xanthine oxidase (XOD) activities. Oral administration of cassia oil significantly reduced serum and hepatic urate levels in hyperuricemic mice in a time- and dose-dependent manner. At doses of 450 mg/kg of cassia oil or above, serum urate levels of the oxonate-pretreated mice were not different from the normal control mice. Cassia oil at 600 mg/kg was found to be as potent as allopurinol, which reduced hepatic urate levels to lower than normal. In normal mice, urate levels in liver, but not in serum, were altered with dose-dependent decrease after cassia oil treatment. Furthermore, the ratio, liver uric acid/serum uric acid, was determined after cassia oil administration with time- and dose-dependent decreases in hyperuricemic mice. The positive dose-dependent decrease ratio was also observed after cassia oil treatment in the normal animals. The decreased extent of ratio elicited by cassia oil in normal mice appeared to be greater than that in the hyperuricemic animal. In addition, cassia oil significantly exhibited marked reductions in liver XDH/XOD activities, with an apparent dose-dependence in the normal and hyperuricemic mice. The onset of inhibition in enzyme activities elicited by allopurinol was much higher than that elicited by cassia oil. These results suggested that hypouricemic effects of cassia oil could be explained, at least partly, by inhibiting liver in vivo activities of XDH/XOD.

GABAergic modulation mediates antinociception produced by serotonin applied into thalamic nucleus submedius of the rat

Our previous studies have indicated that the thalamic nucleus submedius (Sm) is involved in modulation of nociception as part of an ascending component of an endogenous analgesic system consisting of spinal cord-Sm-ventrolateral orbital cortex (VLO)-periaqueductal gray (PAG)-spinal cord loop and that microinjection of 5-hydroxytryptamine (5-HT) into Sm produces antinociception. The aim of the present study was to examine whether the gamma-aminobutyric acid (GABA)ergic modulation is involved in the Sm 5-HT-evoked antinociception. Experiments were carried out on lightly anesthetized rats with an implanted cannula targeting the Sm nucleus. The microinjection of GABA(A) receptor antagonist bicuculline dose-dependently depressed the tail flick (TF) reflex. A smaller dose (100 ng) of bicuculline enhanced the inhibition of TF reflex produced by 5-HT application into Sm, whereas application of GABA (2.5 microg) did not influence the TF reflex but significantly attenuated the 5-HT-evoked inhibition. These results indicate that GABA(A) receptor may be involved in mediating the 5-HT-induced antinociception in Sm possibly through a disinhibition mechanism.

5-hydroxytryptamine 1A (5-HT1A) but not 5-HT3 receptor is involved in mediating the nucleus submedius 5-HT-evoked antinociception in the rat

Our previous studies have indicated that the thalamic nucleus submedius (Sm) is involved in modulation of nociception as part of an ascending component of an endogenous analgesic system consisting of spinal cord-Sm-ventrolateral orbital cortex (VLO)-periaqueductal gray (PAG)-spinal cord loop. Microinjection of 5-hydroxytryptamine (5-HT) into Sm produces antinociception and this effect is blocked by 5-HT(2) receptor antagonist. The aim of the present study was to examine whether the 5-HT(1) and 5-HT(3) receptors were also involved in the Sm 5-HT-evoked antinociception. Nociception was assessed in lightly anesthetized rats with radiant-heat-evoked tail flick (TF). 5-HT(1A) and 5-HT(3) receptor antagonists were microinjected into the Sm alone or in combination with a microinjection of 5-HT into the same Sm site. 5-HT(1A) receptor antagonist p-MPPI (0.87 nmol) facilitated the TF reflex; a lower dose (0.43 nmol) of p-MPPI significantly attenuated the Sm 5-HT-evoked inhibition of TF reflex. Microinjection of the 5-HT(3) receptor antagonist LY-278,584 (12 nmol) had no effect either on the TF reflex or on the Sm 5-HT-evoked inhibition. These results suggest that 5-HT(1A) receptor but not 5-HT(3) receptor is involved in mediating the 5-HT-evoked antinociception. Possible mechanisms of Sm 5-HT-induced descending antinociception are discussed.

Neurochemical phenotype of vagal afferent neurons activated to express C-FOS in response to luminal stimulation in the rat

The vagus nerve conveys meal-induced primary afferent responses to the brainstem. Electrophysiological studies indicate that luminal stimuli such as osmolarity and the digestion products of carbohydrates elicit powerful vagal nodose neuronal responses by activating serotonin 3 (5-hydroxytryptamine-3, 5-HT3) receptors on intestinal mucosal afferent fibers. To characterize the neurochemical phenotype of neurotransmitters in vagal nodose neurons that are activated by luminal stimulation, we examined c-fos protein (c-Fos) expression in response to luminal stimulation in conscious rats. A double-labeling technique using antisera to glutamate (Glu), substance P (SP), calcitonin gene-related peptide (CGRP), and somatostatin (SS) was used to determine the neurochemical profile of c-Fos-positive neurons. c-Fos immunoreactivity was insignificant in vehicle-treated rats. Luminal perfusions of NaCl (500 mOsm), tap water (5 mOsm), maltose (300 mmol/l), and 5-HT (10(-5) mol/l) each elicited a significant increase in the number of cells expressing c-Fos. Chronic vagotomy eliminated an increase in nodose neuronal c-Fos expression, and the 5-HT3 receptor antagonist granisetron significantly reduced it. Glu-, SP-, and CGRP-containing neurons represented 28%, 53%, and 19%, respectively, of the total population of nodose neurons. Few neurons contained SS. Double-labeling studies revealed that of the c-Fos-positive neurons responsive to hypertonic NaCl, 52%, 41%, and 3% exhibited immunoreactivity for Glu, SP, and CGRP, respectively. Of those responsive to tap water, 47%, 50%, and 4% exhibited immunoreactivity for Glu-, SP- and CGRP, respectively. In addition, 44%, 38%, and 8% of 5-HT-stimulated and 30%, 32%, and 5% of maltose-stimulated c-Fos-positive neurons exhibited, respectively, Glu, SP, and CGRP immunoreactivity. The few neurons that contained SS did not express c-Fos.

CONCLUSIONS

Vagal primary afferent neurons that respond to 5-HT-dependent luminal stimuli, such as hyperosmolarity and maltose, contain mainly Glu and SP. These neurons appear to play an important role in the mediation of the vago-vagal reflex elicited by luminal stimuli.

Differential effects of opioid receptors in nucleus submedius and anterior pretectal nucleus in mediating electroacupuncture analgesia in the rat

Previous studies have indicated that the thalamic nucleus submedius (Sm) and the anterior pretectal nucleus (APtN) are involved in the descending modulation of nociception. The aim of the present study was to examine whether the opioid receptors in the Sm and APtN mediated the electroacupuncture (EA)-produced analgesia. The latency of tail flick (TF) reflex induced by radiant heat was used as an index of nociceptive response. The effects of microinjection of opioid receptor antagonist naloxone (1.0 microg, 0.5 ml) into Sm or APtN on the inhibition of the TF reflex induced by EA of "Zusanli" point (St. 36) with high- (5.0 mA) and low- (0.5 mA) intensity were examined in the lightly anesthetized rats. Sm microinjection of naloxone blocked the high- but not low-intensity EA-induced inhibition of the TF reflex. In contrast, naloxone applied to APtN blocked the low- but not high-intensity EA-induced inhibition. When naloxone applied to other brain regions adjacent to Sm or APtN, the EA-induced inhibition was not influenced under either high- or low-intensity condition. These results suggest that opioid receptors in Sm are involved in mediating the analgesia by high-intensity EA for exciting small (A-delta and C group) afferent fibers, while opioid receptors in APtN are involved in mediating the analgesia induced by low-intensity EA for only exciting large (A-beta) afferent fibers.

An experimental study on biomass air-steam gasification in a fluidized bed

The characteristics of biomass air-steam gasification in a fluidized bed are studied in this paper. A series of experiments have been performed to investigate the effects of reactor temperature, steam to biomass ratio (S/B), equivalence ratio (ER) and biomass particle size on gas composition, gas yield, steam decomposition, low heating value (LHV) and carbon conversion efficiency. Over the ranges of the experimental conditions used, the fuel gas yield varied between 1.43 and 2.57 Nm3/kg biomass and the LHV of the fuel gas was between 6741 and 9143 kJ/Nm3. The results showed that higher temperature contributed to more hydrogen production, but too high a temperature lowered gas heating value. The LHV of fuel gas decreased with ER. Compared with biomass air gasification, the introduction of steam improved gas quality. However, excessive steam would lower gasification temperature and so degrade fuel gas quality. It was also shown that a smaller particle was more favorable for higher gas LHV and yield.

Cellular signaling mechanisms underlying pharmacological action of Bak Foong Pills on gastrointestinal secretion

Bak Foong Pills (BFP, also known as Bai Feng Wan) is an over-the-counter traditional Chinese medicine that has long been used for treating gynecological disorders and improving overall body functions, including gastrointestinal (GI) function. However, the cellular signaling mechanism underlying BFP action, especially on the GI tract, has not been elucidated. In the present study, the human colonic epithelia cell line T(84) was used as a model to investigate the effect of BFP ethanol extract on ion transport in conjunction with the short-circuit current (I(SC)) technique. The results showed that the apical addition of BFP extract produced a concentration-dependent (10-1,000 microg/ml, EC(50) = 120 microg/ml) increase in I(SC). The maximal response was observed at 500 microg/ml with an increase in I(SC) of 24.4 +/- 2.3 microA/cm(2) and apical conductance. The BFP-induced I(SC) was not observed when extracellular Cl(-) was replaced or when treated with Bumetanide (100 microM), an inhibitor of the Na(+)-K(+)-2Cl(-) cotransporter. The BFP-induced I(SC) was insensitive to the Na(+) channel blocker, amiloride, but partially inhibited by the Cl(-) channel blocker, DIDS (100 microM), and completely blocked by DPC (2 mM) or glibenclamide (1 mM) with a significant reduction in the apical conductance. The BFP-induced I(SC) could be mimicked by forskolin (10 microM), but inhibited by a pretreatment of the cells with adenylate cyclase inhibitor, MDL-12330A (10 microM). Pretreatment with EGTA (5 mM) and thapsigargin (10 microM) decreased the BFP-induced I(SC) by 10%. These results demonstrated that BFP ethanol extract exerted a stimulatory effect on gastrointestinal Cl(-) secretion by predominantly activating adenylate cyclase and apical cAMP-dependent Cl(-) channels, with minor contributions from calcium-dependent Cl(-) channels. The effect of BFP may be explored to treat GI disorders such as constipation.

Quasiparticle states around a nonmagnetic impurity in a d-density-wave state of high-T(c) cuprates

The electronic structure around a single nonmagnetic impurity in the d-density-wave (DDW) ordering is studied. It is found that a single subgap resonance peak appears in the local density of states around the impurity. In the unitary limit, the position of this resonance peak shifts away from the Fermi energy in accord with the chemical potential. This result is dramatically different from the case of the pure superconducting state for which the impurity resonant energy is approximately pinned at the Fermi level. This can be used to probe the existence of the DDW ordering in cuprates.

Intestinal serotonin acts as paracrine substance to mediate pancreatic secretion stimulated by luminal factors

We recently demonstrated that luminal factors such as osmolality, disaccharides, and mechanical stimulation evoke pancreatic secretion by activating 5-hydroxytryptamine subtype 3 (serotonin-3, 5-HT3) receptors on mucosal vagal afferent fibers in the intestine. We hypothesized that 5-HT released by luminal stimuli acts as a paracrine substance, activating the mucosal vagal afferent fibers to stimulate pancreatic secretion. In the in vivo rat model, luminal perfusion of maltose or hypertonic NaCl increased 5-HT level threefold in intestinal effluent perfusates. Similar levels were observed after intraluminal 10(-5) M 5-HT perfusion. These treatments did not affect 5-HT blood levels. In a separate study, intraduodenal, but not intraileal, 5-HT application induced a dose-dependent increase in pancreatic protein secretion, which was not blocked by the CCK-A antagonist CR-1409. Acute vagotomy, methscopolamine, or perivagal or intestinal mucosal application of capsaicin abolished 5-HT-induced pancreatic secretion. In conscious rats, luminal 10(-5) M 5-HT administration produced a 90% increase in pancreatic protein output, which was markedly inhibited by the 5-HT3 antagonist ondansetron. In conclusion, luminal stimuli induce 5-HT release, which in turn activates 5-HT3 receptors on mucosal vagal afferent terminals. In this manner, 5-HT acts as a paracrine substance to stimulate pancreatic secretion via a vagal cholinergic pathway.

Quasiparticle states at a d-wave vortex core in high- T(c) superconductors: induction of local spin density wave order

The local density of states (LDOS) at the vortex lattice cores in a high- T(c) superconductor is studied by using a self-consistent mean-field theory including interactions for both antiferromagnetism (AF) and d-wave superconductivity (DSC). In a zero-field optimally doped sample the AF order is completely suppressed while DSC prevails. In the mixed state, we show that the local AF-like spin density wave order appears near the vortex core and acts as an effective local magnetic field on electrons via Zeeman coupling. As a result, the LDOS at the core exhibits a double-peak structure near the Fermi level that is in good agreement with recent scanning tunneling microscopy observations.

Temporal and spatial gene expression of major bone extracellular matrix molecules during embryonic mandibular osteogenesis in rats

It is not known how gene expression of bone extracellular matrix molecules is controlled temporally and spatially, or how it is related with morphological differentiation of osteoblasts during embryonic osteogenesis in vivo. The present study was designed to examine gene expressions of type I collagen, osteonectin, bone sialoprotein, osteopontin, and osteocalcin during mandibular osteogenesis using in situ hybridization. Wistar rat embryos 13-20 days post coitum were used. The condensation of mesenchymal cells was formed in 14-day rat embryonic mandibles and expressed genes of pro-alpha 1 (I) collagen, osteonectin, bone sialoprotein and osteopontin. Cuboidal osteoblasts surrounding the uncalcified bone matrix were seen as early as in 15-day embryonic mandibles, while flat osteoblasts lining the surface of the calcified bone were seen from 16-day embryonic mandibles. Cuboidal osteoblasts expressed pro-alpha 1(I) collagen, osteonectin and bone sialoprotein intensely but osteopontin very weakly. In contrast, flat osteoblasts expressed osteopontin very strongly. Osteocytes expressed the extracellular matrix molecules actively, in particular, osteopontin. The present study demonstrated the distinct gene expression pattern of type I collagen, osteonectin, bone sialoprotein, osteopontin and osteocalcin during embryonic mandibular osteogenesis in vivo.

Gene and protein expressions of type I collagen are regulated tissue-specifically in rat hyaline cartilages in vivo

The present study was designed to investigate how rat hyaline cartilages at various sites in vivo express the gene and protein of type I collagen using in situ hybridization and immunohistochemistry. The gene of pro alpha 1(I) collagen was expressed by chondrocytes in articular cartilage, and the protein of type I collagen was identified in the cartilage matrix. In contrast, growth plate cartilage expressed the gene of pro alpha 1(I) collagen, but no protein of type I collagen. Neither gene nor protein of type I collagen was expressed in cartilages of trachea and nasal septum. The present study suggested that expression of type I collagen in hyaline cartilages may be regulated tissue-specifically at gene and/or protein levels.

Distinctive expression of extracellular matrix molecules at mRNA and protein levels during formation of cellular and acellular cementum in the rat

Little is known about differential expression of extracellular matrices secreted by cementoblasts between cellular and acellular cementum. We hypothesize that cementoblasts lining acellular cementum express extracellular matrix genes differently from those lining cellular cementum, thereby forming two distinct types of extracellular matrices. To test this hypothesis, we investigated spatial and temporal gene expression of selected extracellular matrix molecules, that is type I collagen, bone sialoprotein, osteocalcin and osteopontin, during formation of both cellular and acellular cementum using in situ hybridization. In addition, their extracellularly deposited and accumulated proteins were examined immunohistochemically. The mRNA transcripts of pro-alpha1 (I) collagen were primarily localized in cementoblasts of cellular cementum and cementocytes, while those of bone sialoprotein were predominantly seen in cementoblasts lining acellular cementum. In contrast, osteocalcin was expressed by both types of cementoblasts and cementocytes and so was osteopontin but only transiently. Our immunohistochemical examination revealed that translated proteins were localized extracellularly where the genes had been expressed intracellularly. The present study demonstrated the distinctive expression of genes and proteins of the extracellular matrix molecules between cellular and acellular cementum.

Intestinal serotonin acts as a paracrine substance to mediate vagal signal transmission evoked by luminal factors in the rat

The vagus nerve conveys primary afferent information produced by a meal to the brainstem. Serotonin (5-HT), which abounds in intestinal enterochromaffin cells, is released in response to various stimuli. We have recently demonstrated that 5-HT released from intestinal enterochromaffin cells activates 5-HT3 receptors on vagal afferent fibres to mediate luminal non-cholecystokinin-stimulated pancreatic secretion. The present study was designed to evaluate the responses of vagal sensory neurons to intraluminal osmotic stimulation and luminal infusion of maltose, glucose or 5-HT. We investigated the role of endogenous 5-HT in signal transmission evoked by luminal stimuli to activate vagal sensory neurons. The discharges of vagal primary afferent neurons innervating the intestine were recorded from rat nodose ganglia. Luminal factors such as intestinal osmotic stimuli and perfusion of carbohydrates elicited powerful vagal nodose responses. Electrical subdiaphragmatic vagal stimulation activated 364 single units; 40 of these responded to intestinal mucosal stimuli. Of these 40, 30 responded to intraduodenal perfusion of hyperosmolar NaCl (500 mosmol l(-1)), 27 responded to tap water (5 mosmol l(-1)) and 20 and 19 responded to maltose (300 mM) and glucose (277.5 mM), respectively. The 5-HT3/4 antagonist tropisetron (ICS 205-930) or 5-HT3 antagonist granisetron abolished luminal stimuli-evoked nodose neuronal responses. Intraluminal infusion of 10(-5) and 10(-4) M 5-HT elicited increases in vagal afferent discharge in 25 and 31 units, respectively, by activating the 5-HT3 receptors. Acute subdiaphragmatic vagotomy, intestinal mucosal application of the local anaesthetic lidocaine (lignocaine) or administration of 5-HT3 antagonist each abolished the luminal 5-HT-induced nodose neuronal responses. In contrast, distension-sensitive neurons did not respond to duodenal infusion of 5-HT. Pharmacological depletion of 5-HT stores using p-chlorophenylalanine (PCPA), a 5-HT-synthesis inhibitor, abolished luminal factor-stimulated nodose neuronal responses. In contrast, pretreatment with 5,7-dihydroxytryptamine (5,7-DHT), a specific 5-HT neurotoxin that destroys 5-HT-containing neurons without affecting 5-HT-containing mucosal cells, had no effect on these responses. These results suggested that the nodose neuronal responses to luminal osmolarity and to the digestion products of carbohydrates are dependent on the release of endogenous 5-HT from the mucosal enterochromaffin cells, which acts on the 5-HT3 receptors on vagal afferent fibres to stimulate vagal sensory neurons.

Annonaceous acetogenins of the seeds from Annona muricata

Muricatenol (1) is a new C37 non-THF ring acetogenin with four hydroxyls and one isolated double bond in the long aliphatic chain. 2,4-cis-Gigantetrocinone (2) and 2,4-trans-gigantetrocinone (3) have been isolated as their acetates by preparative TLC. 2,4-trans-Isoannonacin-10-one (4) and 2,4-trans-isoannonacin (5) have been isolated as only 2,4-trans-form for the first time (no cis-form). Also four known acetogenins, gigantetrocin-A (6), gigantetrocin-B (7), annomontacin (8), gigantetronenin (9) and a mixture of N-fatty acyl tryptamines have been isolated (10). Their structures have been established on the basis of spectral analyses. The CHCl3 fraction of the seeds showed strong antitumor activities.

Quasiparticle localization in disordered d-wave superconductors

An extensive numerical study is reported on the disorder effect in two-dimensional d-wave superconductors with random impurities in the unitary limit. It is found that a sharp resonant peak shows up in the density of states at zero energy and correspondingly the finite-size spin conductance is strongly enhanced which results in a nonuniversal feature in one-parameter scaling. However, all quasiparticle states remain localized, indicating that the resonant density peak alone is not sufficient to induce delocalization. In the weak disorder limit, the localization length is so long that the spin conductance at small sample size is close to the universal value predicted by Lee [Phys. Rev. Lett. 71, 1887 (1993)].

Immunohistochemical localization of type I collagen, fibronectin and tenascin C during embryonic osteogenesis in the dentary of mandibles and tibias in rats

Type I collagen, fibronectin and tenascin C play an important role in regulating early osteoblast differentiation, but the temporal and spatial relationship of their localization during embryonic osteogenesis in vivo is notknown. The present study was designed to localize these three molecules in the dentary of mandibles and tibias in rat embryos using immunohistochemistry. Serial paraffin sections were cut and adjacent sections were processed for von Kossa staining or immunohistochemistry for type I collagen, fibronectin and tenascin C. In the dentary, tenascin C was localized within and around the mesenchymal cell condensation in embryos at 14 days in utero. The bone matrix at 15 days showed immunoreactivity for both type I collagen and fibronectin. The immunoreactivity of type I collagen was persistent, whereas that of fibronectin decreased with age of embryos. In tibias, tenascin C was localized in the perichondral mesenchymal tissue at 17 days. Immunoreactivity for type I collagen was persistent in the bone matrix, whereas the tibial bone showed little immunoreactivity for fibronectin at any embryonic age examined. The present study demonstrated characteristic localization of type I collagen, fibronectin and tenascin C during embryonic osteogenesis in the dentary of mandibles and tibias.

Expression of major bone extracellular matrix proteins during embryonic osteogenesis in rat mandibles

It is not known how bone proteins appear in the matrix before and after calcification during embryonic osteogenesis. The present study was designed to investigate expressions of the five major bone extracellular matrix proteins--i.e. type I collagen, osteonectin, osteopontin, bone sialoprotein and osteocalcin--during osteogenesis in rat embryonic mandibles immunohistochemically, and their involvement in calcification demonstrated by von Kossa staining. Wistar rat embryos 14 to 18 days post coitum were used. Osteogenesis was not seen in 14-day rat embryonic mandibles. Type I collagen was localized in the uncalcifed bone matrix in 15-day mandibles, where no other bone proteins showed immunoreactivity. Osteonectin, osteopontin, bone sialoprotein and osteocalcin appeared almost simultaneously in the calcified bone matrix of 16-day mandibles and accumulated continuously in 18-day mandibles. The present study suggested that type I collagen constitutes the basic framework of the bone matrix upon which the noncollagenous proteins are oriented to lead to calcification, whereas the noncollagenous proteins are deposited simultaneously by osteoblasts and are involved in calcification cooperatively.

A new kinetic model of protein adsorption on suspended anion-exchange resin particles

The kinetics of adsorption of bovine serum albumin on an anion-exchange resin were measured in a batch system using a flow cell and ultraviolet absorbance, as a function of initial liquid-phase protein concentration and solid-to-liquid phase ratio. A new mathematical model for adsorption kinetics is presented that fits the experimental data to give a highly linear relationship with time, following a short transient period. Numerical integration of the differential form of the new composite nonlinear (CNL) kinetic model, containing three independent parameters, is shown to describe the dynamics of batch adsorption much better than alternative lumped parameter models. Although the new model is phenomenological rather than mechanistic, its principal parameter is shown to be a direct linear function of a physically measurable quantity. This study demonstrates that the model can accurately simulate protein concentration-time profiles using parameter estimates derived from correlations over a wide range of initial protein concentrations and phase ratios. The new CNL model is shown to be considerably superior to the Langmuir and solid-film linear kinetic models in this regard, having the additional advantage that an equilibrium isotherm for the system is not required.

Tumor radiosensitization by sustained intratumoral release of bromodeoxyuridine

We have previously reported that the use of the polymer bis(p-carboxyphenoxy)propane-sebacic acid (20:80) for intratumoral delivery of cis-platinum in a mouse tumor model (RIF-1) potentiated the effects of acute and fractionated radiation. This mode of drug delivery seems particularly applicable to the administration of radiosensitizing drugs because an optimum concentration of radiosensitizer can be maintained in the tumor over the prolonged period required for fractionated radiation treatment. We have now investigated, in the same tumor model, radiosensitization by the thymidine analogue bromodeoxyuridine (BrdUrd). BrdUrd (20%, w/w) was incorporated into bis(p-carboxyphenoxy)propane-sebacic acid (20:80) and polymer rods containing the drug implanted in the RIF-1 tumor. Preliminary in vitro studies of the rate of release of BrdUrd from the polymer showed an initial rapid loss over 24 h, followed by a slower release extending over the next 5 days. In experiments in which tumor cells, which had incorporated BrdUrd in vivo from implanted polymer, were excised and a single cell suspension irradiated in vitro radiosensitization indicative of BrdUrd incorporation was associated mainly with an increase in the alpha constant for the linear quadratic model of cell survival. Radiosensitization was seen for tumor cells harvested between 5 and 10 days after polymer implant, a finding that is consistent with results of experiments in which the percentage of cells that had incorporated BrdUrd were measured by flow cytometry at various times after polymer/BrdUrd implant. The proportion of tumor cells positive for BrdUrd was 40-50% between 3 and 8 days after polymer implant. When tumors were irradiated in situ and response measured in terms of tumor growth delay (TGD), radiosensitization was not seen for an acute dose of 16.5 Gy. In contrast, significant radiosensitization was seen for fractionated treatments when polymer/BrdUrd was implanted 3 days before the first radiation dose. For a dose of 5 x 6 Gy, TGD was increased from 22 days for radiation alone to 27 days for radiation plus polymer implant. For 10 x 6 Gy fractions, TGD increased from 45-77 days for those mice in whom the tumor eventually regrew, whereas for 25% of the mice in this group the tumor volume was reduced to a point where it was no longer detectable and there was no recurrence for at least 120 days after treatment.

Development of interglobular dentine in rat molars and its relation to maturation of enamel

The development of interglobular dentine in the first upper and lower molars of Wistar rats aged 3, 7, 14, 21, 42 days was examined histochemically using a lectin, succinyl wheat germ agglutinin (sWGA), which is specific for N-acetyl-D-glucosamine. sWGA stained the interglobular dentine, predentin and Golgi area of odontoblasts. Interglobular dentine was not formed in the first molars of 3-day rats, but appeared in those of 7-day rats near the enamel-free area. In 14-day rats, interglobular dentine was present in most areas of the coronal dentine except the cervical area. At the interface between dentine and predentin, numerous sWGA-negative calcospherites were seen, suggesting that the interglobular dentine is formed actively there. In 21-day rats, the interlobular dentine was more numerous than in 14-day rats. Interglobular dentine was present in the cervical root dentine as well as in the coronal dentine, including the cervical area. The distribution of interglobular dentine in 42-day rats was similar to that in 21-day rats, but fluorescence of sWGA binding was less intense in the former. Because the development of interglobular dentine appeared to be time and position specific its relation to the stages of ameloblasts was analysed. Thin enamel matrix was formed at cusps in molars of 3-day rats and thickness of enamel matrix increased in 7-day rats. In these teeth, the ameloblasts were at the differentiating or secretory stage. The Golgi area and Tomes' processes of the secretory ameloblasts, the cells of intermediate layer and the enamel matrix were weakly positive with sWGA. The epithelial cells at the enamel-free area were also stained with sWGA. In 14-day rats, most of the ameloblasts in the first maxillary molars were at the maturative stage except in the cervical area, where the ameloblasts were at the transitional stage. sWGA stained the distal border and the Golgi area of the maturative ameloblasts as well as the cells of the papillary layer. The distal border of the maturative ameloblasts appeared either thick or thin, suggesting a ruffle-end and smooth-end of the cells. Ameloblasts were absent in the first molars of 21-day rats and the cervical part of the enamel was covered with the stratified epithelium like that of 42-day rats. The present study has demonstrated that interglobular dentine contains sWGA-binding glycoconjugates and the formation of the interglobular dentine is largely associated with the enamel maturation. These results suggest that matrix-to-cell interaction is important for the development of interglobular dentine.