Biomedical subjects

Lei Chen

Publications and source records attributed to Lei Chen.

At least 73 records · Page 4Linked to original sources

PubMed2006

[Observation on clinical therapeutic effect of transcutaneous point electric stimulation on periarthritis of shoulder at different stages].

OBJECTIVE: To observe the therapeutic effect of transcutaneous point electric stimulation on periarthritis of shoulder at different stages and compare with electroacupuncture. METHODS: Three hundred and sixty cases of periarthritis of shoulder at different stages were divided into a treatment group (n=186) treated with transcutaneous point electric stimulation, and a control group (n=174) treated with electroacupuncture. Same acupoints were selected in the two groups. RESULTS: The total effective rate of transcutaneous point electric stimulation was 96.6% at the adhesion prophase and 96.9% at the adhesive stage, but electroacupuncture stimulation was 93.5% and 97.9%, respectively, with no significant differences between the two groups; transcutaneous point electric stimulation not only could relieve pain, but also significantly improve dysfunction of shoulder joints at the adhesive stage. CONCLUSION: Transcutaneous point electric stimulation is an effective and convenient therapy for periarthritis of shoulder.

Acupuncture Points↗

PubMed2006

[Antibacterial effect of Jinzhi Hanshuye on infected root canals].

PURPOSE: To evaluate antibacterial effects of Jinzhi Hanshuye on infected root canals. METHODS: 30 infected single-root-canals were collected from 27 clinical patients, and randomly divided into two groups. In the experimental group, Jinzhi Hanshuye was used as irrigating solution and intracanal medicament, while in the control group tosylchloramide sodium irrigating and calcium hydroxide disinfecting root canals were adopted. Microbiological sampling was performed before treatment, after instrumentation, and after intracanal medication. The frequency of positive culture and CFU of each culture were evaluated by ANOVA. RESULTS: The frequency of positive culture was dropped from 73.3% to 46.7% after instrumentation and to 13.3% after medication in the experimental group, while in the control group the frequency was dropped from 73.3% to 20.0% and 26.7% after medication (P=0.9721). CFU was dropped from 1462.9 to 27.9 after instrumentation and 15.7 after medication, while in the control group CFU was dropped from 1402.8 to 14.0 and 45.1 after medication (P=0.688). CONCLUSIONS: Jinzhi Hanshuye had good antibacterial effects on anaerobics of infected root canals.

Anti-Bacterial Agents↗

PubMed2006

[Semantic extension to DICOM standard].

The Digital Imaging and Communications in Medicine (DICOM) Standard was developed by National Electrical Manufacturers Association (NEMA) and the American College of Radiology (ACR) for medical image archiving and communication. The Standard is widely used in medicine now. But it does not define image semantic content sufficiently, so there is a difficulty in the implementation based on semantic content. In this article are discussed the semantic hierarchy structure in medical image and the method to describe the image content used in the DICOM Standard. We point out the limitations of DICOM in image semantic content description, and then set forth a way to extend the semantic content description by using DICOM private attributes.

Computer Communication Networks↗

PubMed2006

[Study on different onset patterns and perinatal outcomes in severe preeclampsia].

OBJECTIVE: To explore the different clinical onset patterns in severe preeclampsia. METHODS: A prospective observational study was conducted in 173 cases of severe preeclampsia. They were divided into two groups according to the onset of gestational age of severe preeclampsia, early onset of severe preeclampsia (S-PE) (onset < or = 34 weeks) and late onset of S-PE (onset > 34 weeks). Then according to the onset pattern they were subdivided into 4 subgroups: early abrupt onset (10) and early onset with gradual progress of severe preeclampsia (87), late abrupt onset (18) and late onset with gradual progress of severe preeclampsia (58). Clinical characteristics in each subgroup were evaluated. RESULTS: Cases with abrupt onset accounted for 16.2% out of 173 cases of severe preeclampsia (28/173). The incidence of abrupt onset or onset with gradual progress between early and late onset groups was not significantly different (P > 0.05). Whether in early onset group or late onset group, the incidence of serious maternal complications was much higher in abrupt onset subgroups than that in gradual progress subgroups [100.0% (10/10) vs 34.5% (30/87) and 100.0% (18/18) vs 29.3% (17/58); P < 0.001]. The incidence of serious maternal complications was not significantly different between early onset and late onset groups (P > 0.05). The perinatal mortality rate was higher in abrupt onset subgroups compared to gradual progress subgroups both in early onset groups and in late onset ones (72.7% vs 24.3%, P < 0.01; 22.2% vs 4.9%, P < 0.05). The perinatal mortality rate was higher in each subgroups in early onset groups than that in late onset ones respectively (P < 0.01, P < 0.05). The gestational age at delivery was closely associated with perinatal outcomes. When a delimitation of early onset of severe preeclampsia was set at 32-week gestation, perinatal outcome was associated with both gestational age at birth and the onset time of severe preeclampsia. If the cut-off point was set at 34-week gestation, perinatal outcome was associated only with gestational age at birth. CONCLUSIONS: Approximately 16% pregnant women with severe preeclampsia were attacked abruptly and complicated by serious complications. The clinical delimitation of early onset of severe preeclampsia set at 32-week gestation is significantly associated with poor maternal and perinatal outcomes.

Adult↗

PubMed2006

[Surgical approach and materials in reparation of cerebrospinal rhinorrhea (54 cases reports)].

OBJECTIVE: To find out the best surgical approach and repair material in repairing cerebrospinal rhinorrhea by comparing their characteristics. METHOD: The clinical data of 54 cases from March 1983 to June 2001 with continuous cerebrospinal rhinorrhea treated by different approaches and repair materials were retrospective analyzed. RESULT: The highest recurrent rate was by anterior cranial fossa approach, while the lowest was by nasal endoscope. The bleeding volume in nasal endoscope approach was less than other surgical approaches with the significant differences (P <0.01). Galea frontalis myofascial flap and fascia lata were often used to repair fistula in operation. CONCLUSION: Nasal endoscope is the best approach. Cranionasal combination approach can be used in cases with larger defect in basis crania by galea frontalis myofascial flap reparation. The proper approach and repair materials should be selected according to the practical situation.

Adolescent↗

PubMed2006

[Effect of porcelain firing cycle on microstructure and corrosion resistance of 4 metal ceramic alloys].

OBJECTIVE: To determine the effect of porcelain firing cycle on microstructure of 4 metal ceramic alloys, and to analyze the changes of their corrosion resistance in the artificial saliva. METHODS: We simulated the process of firing and repolishing when fabricating porcelain-fused-to-metal restoration in clinic,and then observed the microstructures of Ni-Cr, Ni-Cr-Ti, Co-Cr alloys and high gold alloy by field emission scanning electron microscopy and energy dispersive spectroscopy. The electrochemical corrosion behavior of alloys in artificial saliva was analyzed by polarization curves and corrview 2 corrosion analysis software. The data of self-corrosion potential and transpassive potential were obtained and analyzed. RESULTS: After the porcelain firing cycle, the surface composition changed slightly, and the morphological in the 3 predominate base metal alloys also changed. The self-corrosion potential turned to more negative, and the transpassive potential declined. CONCLUSION: The procedure of porcelain firing cycle can affect the surface microstructure and increase the corrosion of 4 metal-ceramic alloys.

Corrosion↗

PubMed2006

[Application of pedicled anterolateral thigh flap transferring for coverage of oversized skin defect of hand].

OBJECTIVE: To introduce the application of the pedicled anterolateral thigh flap transferring for coverage of the oversized skin defect of the hand. METHODS: The pedicled anterolateral thigh flap was transferred to cover the large skin defects of the hands or the skin defects of the abdomen after the abdominal flap transferred to the hand in 5 male patients aged 16-44 years from April 2002 to August 2005. The injured sites were as follows:4 right hands and 1 left hand, including 2 hands injured by a machine and 3 hands injured by burning. The mechanically injured patients underwent an operation within 6 hours after the injury. The burned patients were reconstructed by the flap transferring 4-7 days after the burn when the decayed tissues could be clearly indentified. The areas of the hand defects were 12-19 cm x 18-22 cm. The areas of the pedicled anterolateral thigh flaps were 7-12 cm x 16-24 cm. The areas of the abdominal flaps were 13-20 cm x 19-23 cm. The pedicles were separated 3 weeks after the repairing operation. RESULTS: All the flaps survived well and there was no vascular crisis, with the wound healing of the first intention. The skin defects of the hand were covered completely. Five patients were followed up for 6-12 months. The texture of the flaps was soft and the flaps had a good blood circulation. Of the patients, 3 underwent the finger exclusion and degreasing operation 4-7 months after operation. All the flaps of the hands had protective sensation, which could meet the requirement of the daily life. CONCLUSION: The pedicled anterolateral thigh flap can provide the large coverage for the skin defects of the hands. The risk of the operation can be greatly decreased by obviation of the vessel anastomosis. It can be an optimal choice for the management of the oversized skin defects of the hands.

Adolescent↗

PubMed2005

Combined DFT theoretical calculation and solid-state NMR studies of Al substitution and acid sites in zeolite MCM-22.

The distributions of Brönsted acidic protons and their acid strengths in zeolite H-MCM-22 have been characterized by density functional theory (DFT) calculations as well as magic angle spinning (MAS) NMR experiments. The embedded scheme (ONIOM) that combines the quantum mechanical (QM) description of active sites and semiempirical AM1 treatment of the neighboring environment was applied to predict the aluminum substitution mechanism and proton affinity (PA), as well as adsorption behaviors of acetone and trimethylphosphine oxide (TMPO) onto the zeolite. Our theoretical results indicate that the Al substitution takes place in the order of Al1-OH-Si2 > Al8-OH-Si8 > Al5-OH-Si7. The DFT theoretical and NMR experimental results suggest that the acid strength of the three Brönsted acid sites in H-MCM-22 zeolite is slightly lower than that of H-ZSM-5 zeolite and the accessible Brönsted acidic protons most likely reside in both the supercages (at the Al8-OH-Si8 and Al1-OH-Si2 sites) and external surface pocket (at the Al8-OH-Si8 site) rather than in the sinusoidal channels (Al5-OH-Si7), with the Al1-OH-Si2 site having the strongest acid strength (as probed by TMPO). This may partially explain the special selectivity of acid-catalyzed reactions occurring inside the channels of H-MCM-22 zeolite.

Journal Article↗

PubMed2005

Angiosarcoma of the breast.

BACKGROUND: Angiosarcoma of the breast is a rare entity. The objectives of this study were to evaluate prognostic factors and determine outcomes in a large contemporary series of patients. METHODS: Clinical and pathologic factors were analyzed in all patients with angiosarcoma of the breast treated between 1990 and 2003. Overall survival (OS) and disease-free survival (DFS) were estimated using the methods of Kaplan and Meier. Multivariate analyses were performed to evaluate prognostic factors. RESULTS: Fifty-five women with angiosarcoma of the breast were identified. The median age was 49.1 years, and the median follow-up time was 3.7 years. The median OS and DFS were 2.96 years and 2.26 years, respectively. For the 32 patients with primary angiosarcoma of the breast 5-year OS was 59%. Twenty-three (42%) patients had received prior radiation therapy for the treatment of breast cancer. These patients with radiation therapy-associated angiosarcoma were on average 30 years older and less likely to present with distant metastatic disease than patients presenting with radiation-naive angiosarcoma of the breast. Although radiation-naive patients appeared to have had better early DFS and OS, the Kaplan-Meier curves were not statistically different between patients with radiation therapy-associated disease and radiation therapy-naive patients. On multivariate analysis, tumor recurrence (P = 0.006) was the only significant adverse prognostic factor noted for OS. CONCLUSIONS: In this series of 55 patients with angiosarcoma of the breast, radiation therapy-naive angiosarcomas occurred in younger patients, but they behaved similarly to radiation therapy-associated angiosarcomas.

Adult↗

PubMed2005

Cardiac myocyte apoptosis is associated with increased DNA damage and decreased survival in murine models of obesity.

Disruption of leptin signaling is associated with obesity, heart failure, and cardiac hypertrophy, but the role of leptin in cardiac myocyte apoptosis is unknown. We tested the hypothesis that apoptosis increases in leptin-deficient ob/ob and leptin-resistant db/db mice and is associated with aging and left ventricular hypertrophy, increased DNA damage, and decreased survival. We studied young (2- to 3-month-old) and old (12- to 14-month-old) ob/ob and db/db mice and wild-type (WT) controls (n=2 to 4 per group). As expected, ventricular wall thickness and heart weights were similar among young ob/ob, db/db, and WT mice, but higher in old ob/ob and db/db versus old WT. Young ob/ob and db/db showed markedly elevated apoptosis by TUNEL staining and caspase 3 levels compared with WT. Differences in apoptosis were further accentuated with age. Leptin treatment significantly reduced apoptosis in ob/ob mice both in intact hearts and isolated myocytes. Tissue triglycerides were increased in ob/ob hearts, returning to WT levels after leptin repletion. Furthermore, the DNA damage marker, 8oxoG (8-oxo-7,8-dihydroguanidine), was increased, whereas the DNA repair marker, MYH glycosylase, was decreased in old ob/ob and db/db compared with old WT mice. Both ob/ob and db/db mice had decreased survival compared with WT mice. We conclude that leptin-deficient and leptin-resistant mice demonstrate increased apoptosis, DNA damage, and mortality compared with WT mice, suggesting that normal leptin signaling is necessary to prevent excess age-associated DNA damage and premature mortality. These data offer novel insights into potential mechanisms of myocardial dysfunction and early mortality in obesity.

Animals↗

PubMed2005

Effects of LPS stimulation on the expression of prostaglandin carriers in the cells of the blood-brain and blood-cerebrospinal fluid barriers.

Prostaglandins produced in cerebral endothelial cells (CECs) are the final signal transduction mediators from the periphery to the brain during fever response. However, prostaglandins are organic anions at physiological pH, and they enter cells poorly using simple diffusion. Several transporters have been described that specifically transport prostaglandins across cell membranes. We examined the expression of the two principal prostaglandin carriers, prostaglandin transporter (PGT), and multidrug resistance-associated protein 4 (MRP4) in cells of the blood-brain barrier and in choroid epithelial cells in vitro as well as in vivo in rat brain in control conditions and after lipopolysaccharide (LPS) challenge. We detected PGT in primary cultures of rat CECs, astrocytes, pericytes, and choroid epithelial cells. LPS stimulation had no effect on the expression level of PGT in these cells; however, after LPS stimulation the polarized, dominantly luminal, expression pattern of PGT significantly changed. MRP4 is also expressed in CECs, and its level was not influenced by LPS treatment. In rat brain, PGT was highly expressed in the supraoptic and paraventricular nuclei of the hypothalamus, in the ependymal cell layer of the third ventricle, and in the choroid plexus. LPS treatment increased the expression of PGT in the supraoptic and paraventricular nuclei. Our results suggest that PGT and MRP4 likely play a role in transporting prostaglandins through the blood-brain and blood-cerebrospinal fluid barriers and may be involved in the maintenance of prostaglandin homeostasis in the brain and in the initiation of fever response.

Animals↗

PubMed2005

New aliphatic nitro-compounds from Indigofera carlesii.

An investigation of aliphatic nitro-compounds in Indigofera carlesii resulted in the identification of two blended novel compounds: 2-O-acryl-3,6-di-O-(3-nitropropanoyl)-alpha-d-glucopyranose and 6-O-acryl-2,3-di-O-(3-nitropropanoyl)-alpha-d-glucopyranose. The structures of the new compounds were elucidated on basis of spectral analysis.

Indigofera↗

PubMed2005

Achromatic wave plates for optical pickup units fabricated by use of imprint lithography.

We report achromatic form-birefringence wave plates for optical pickup units. Material dispersion and structure dispersion are balanced in a rigorous multilayer design. A trilayer grating using SiN(x)/SiO(y)N(z)/SiO2 provides easily accessible process control points and relaxed fabrication tolerance. We demonstrate precise patterning by using nanoimprint lithography on UV-curable polymers, alleviating a major fabrication challenge. The achromatic wave plates exhibit 90+/-3 degrees retardance and >95% transmittance as measured by a Mueller matrix method at wavelengths of 640-800 nm.

Journal Article↗

PubMed2005

Isolation and expression pattern of RGS21 gene, a novel RGS member.

Regulators of G-protein signaling (RGS) proteins are known for the RGS domain that is composed of a conserved stretch of 120 amino acids, which binds directly to activated G-protein alpha subunits and acts as a GTPase-activating protein (GAP), leading to their deactivation and termination of downstream signals. In this study, a novel human RGS cDNA (RGS21), 1795 bp long and encoding a 152-amino acid polypeptide, was isolated by large-scale sequencing analysis of a human fetal brain cDNA library. Unlike other RGS family members, RGS21 gene has no additional domain/motif and may represent the smallest known member of RGS family. It may belong to the B/R4 subfamily, which suggests that it may serve exclusively as a negative regulator of alphai/o family members and/or alphaq/11. PCR analysis showed that RGS21 mRNA was expressed ubiquitously in the 16 tissues examined, implying general physiological roles.

Amino Acid Sequence↗

PubMed2005

Effects of cholecystokinin (CCK)-8 on hypothalamic oxytocin-secreting neurons in rats lacking CCK-A receptor.

Peripheral administration of cholecystokinin (CCK)-8 selectively activates oxytocin (OXT)-secreting neurons in the supraoptic (SON) and the paraventricular nuclei (PVN) with the elevation of plasma OXT level in rats. We examined the effects of intravenous (iv) administration of CCK-8 on the neuronal activity of hypothalamic OXT-secreting neurons and plasma OXT level in Otsuka Long-Evans Tokushima Fatty (OLETF) rats that have a congenital defect in the expression of the CCK-A receptor gene. In situ hybridization histochemistry (ISH) for c-fos mRNA revealed that the expression of the c-fos gene was not induced in the SON, the PVN, the nucleus of the tractus solitarius (NTS) and the area postrema (AP) 30 min after iv administration of CCK-8 (20 and 40 microg/kg) in OLETF rats. In Long-Evans Tokushima Otsuka (LETO) rats (controls), c-fos mRNA was detected abundantly in those nuclei 30 min after iv administration of CCK-8 (20 microg/kg). Immunohistochemistry for c-fos protein (Fos) showed that the distributions of Fos-like immunoreactivity (LI) were identical to the results obtained from ISH. Dual immunostaining for OXT and Fos revealed that Fos-LI was mainly observed in OXT-secreting neurons in the SON and the PVN of LETO rats 90 min after iv administration of CCK-8 (20 microg/kg). Radioimmunoassay for OXT and arginine vasopressin (AVP) showed that iv administration of CCK-8 did not cause significant change in the plasma OXT and AVP levels in OLETF rats, while iv administration of CCK-8 caused a significant elevation of plasma OXT level without changing the plasma AVP level in LETO rats. These results suggest that peripheral administration of CCK-8 may selectively activate the hypothalamic OXT-secreting neurons and brainstem neurons through CCK-A receptor in rats.

Animals↗

PubMed2005

Autocrine peptide mediators of cerebral endothelial cells and their role in the regulation of blood-brain barrier.

A unique feature of cerebral endothelial cells (CECs) is the formation of the blood-brain barrier (BBB), which contributes to the stability of the brain microenvironment. CECs are capable of producing several substances mediating endothelium-dependent vasorelaxation or vasoconstriction, regulating BBB permeability, and participating in the regulation of cell-cell interactions during inflammatory and immunological processes. The chemical nature of these mediators produced by CECs ranges from gaseous anorganic molecules (e.g. nitric oxide) through lipid mediators (e.g. prostaglandins) to peptides. Peptide mediators are a large and diverse family of bioactive molecules which can elicit multiple effects on cerebral endothelial functions. In this review, we summarize current knowledge of peptide mediators produced by CECs, such as adrenomedullin, angiotensin, endothelin and several others and their role in the regulation of BBB functions.

Animals↗

PubMed2005

Adrenomedullin protects rat cerebral endothelial cells from oxidant damage in vitro.

Increased permeability and reduced cerebral endothelial cell (CEC) viability induced by oxidative stress are the hallmarks of the blood-brain barrier disruption. In our experiments hydrogen peroxide (H2O2, 0.5 mM) induced a continuous decrease of the transendothelial electrical resistance (TEER) and resulted in intercellular gap formations in cultured rat CECs. Adrenomedullin (AM) increased TEER, enhanced peripheral localization of F-actin bands and attenuated the increased permeability induced by H2O2. Furthermore, AM treatment preserved mitochondrial membrane potential, attenuated cytochrome c release, and consequently improved CEC viability in H2O2 treated cultures. These results suggest that AM treatment protects CECs against oxidative injury.

Actins↗

PubMed2005

High-performance optical retarders based on all-dielectric immersion nanogratings.

High-performance true zero-order optical retarders were realized based on all-dielectric immersion nanogratings. All-dielectric nanolaminate materials, deposited by atomic layer deposition, were utilized to fill the trenches of the nanogratings to form immersion nanogratings. The refractive index of the nanolaminate material can be dialed and controlled precisely by controlling the ratio of the two compositions forming the nanolaminate material. This significantly improves the design and process windows for realizing precise optical retarders, particularly very-low-phase retarders. Three 100-mm-diameter very-low-phase retarders with highly precise and uniform phase retardance and very high transmittance were realized by use of the all-dielectric immersion grating design and an atomic layer deposition technique.

Journal Article↗