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Biomedical subjects

Bin Chen

Publications and source records attributed to Bin Chen.

At least 73 records · Page 4Linked to original sources
PubMed2006

Phase-contrast magnetic resonance angiography for assessment of intracranial venous sinus lesions.

OBJECTIVE: To review the presentations of intracranial venous sinus lesions in phase-contrast (PC) magnetic resonance angiography (MRA) and discuss the diagnostic value of this imaging modality for these lesions. METHODS: This study involved 52 patients with intracranial venous sinus lesions, including 21 with dural venous sinus malformation, 7 dural arteriovenous fistula (6 caroticocaveneous fistula, CCF), 5 venous sinus thrombus and 19 meningioma invading the venous sinuses. All patients underwent PC and time-of-flight (TOF) MRA with a 1.5 Tesla MR scanner, with 28 of them undergoing subsequent digital subtraction angiography (DSA). RESULTS: PC MRA showed extensive hyperintense signals that identified the lesions, feeding arteries, deferent veins and venous sinuses in 21 cases of dural arteriovenous fistula, but the lesion signals appeared homogeneous. In these cases, PC and TOF MRA had equally good performance in displaying the feeding arteries with success in 20 of the 21 cases (95.2%), whereas the former resulted in a greater rate of deferent vein display [90.5% (19/21)] than the latter [76.2% (16/21), P<0.05]. The 6 CCF cases showed ipsilateral cavernous sinus expansion and upper ophthalmic vein dilations. In the 5 cases of venous sinus thrombis, 4 had transverse sinus thrombus and 1 superior sagittal sinus thrombus. All the cases presented signal disappearance in the sinuses in PC MRA and hyperintense signals in MRI, and some cases had also cerebral superficial hemorrhage and edema. The 19 cases of meningioma invading the venous sinus displayed sinus shift, stenosis and occlusion in PC MRA. CONCLUSION: PC MRA has great advantages in displaying the anatomical structure and lesions of the venous sinuses.

Adolescent↗
PubMed2006

[Clinical observation on chronic severe hepatitis B treated by principles of cooling-blood and detoxicating combined with clearing-heat and resolving-damp or combined with strengthening-Pi and warming-yang].

OBJECTIVE: To observe the therapeutic efficacy on chronic severe hepatitis B (CSH) patients of Yanghuang and Yinhuang syndrome type by principles of cooling-blood and detoxicating combined with clearing-heat and resolving dampness (PA) or with strengthening-Pi and warming-yang (PB), respectively. METHODS: Forty-three patients with CSH were randomly divided into two groups, group A (22 cases) treated with PA and group B (21 cases) with PB. The therapeutic efficacy, laying stress on the effect in eliminating jaundice, was observed. RESULTS: The efficacy in group B was effective in 19 cases (90.5%), and ineffective in 2 (9.5%), while in group A, effective in 16 (72.7%) and ineffective in 6 (27.3%). Levels of TBIL and ALT were significantly lower in both groups (P < 0.05 or P < 0.01), and the descending extent was greater, the thrombinogen activity was higher in group B than that in group A after treatment (P < 0.05), no significant difference in ALT was found between the two groups. CONCLUSION: The efficacy of PB is better than that of PA on CSH with Yanghuang and Yinghuang syndrome.

Adult↗
PubMed2006

[Tadalafil and patients preference in the treatment of erectile dysfunction].

ED treatment has changed fundamentally since phosphodiesterase type 5 inhibitor (PDE5-I) came into clinical use. There are three kinds of PDE5-I available at present, Sildenafil, Vardenafil and Tadalafil. Tadalafil distinguishes from the other two by its uniquely long half-life, which lasts 17.5h, which a pharmacodynamic duration of 36h and not influenced by food and alcohol. Thus it may enable ED patients to accomplish a spontaneous intercourse without the need of prior preparation without, which can boost their confidence and self-esteem and, the most important, improve the relationship with their partner. To know patient preference counts quite a lot in optimizing the medication ED treatment.

Carbolines↗
PubMed2006

[Analysis of several methods for wavelet denoising used in near infrared spectrum pretreatment].

Based on the wavelet analysis, the noise of the near infrared first derivative spectrum of rapeseed oil is eliminated. Several popular wavelet denoising methods are introduced, including wavelet decomposition and reconstruction method, nonlinear wavelet soft-threshold denoising method, and wavelet transform modulus maxima method, The results show that the wavelet transform modulus maxima method is the best, the nonlinear wavelet soft-threshold method is the second, and other are worse. The wavelet transform modulus maxima method can produce more precise model with little deviation.

Fatty Acids, Monounsaturated↗
PubMed2005

Carbohydrate rod conjugates: ternary rod-coil molecules forming complex liquid crystal structures.

T-shaped polyphilic triblock molecules, consisting of a rodlike p-terphenyl unit, a hydrophilic and flexible laterally attached oligo(oxyethylene) chain terminated by an 1-acylamino-1-deoxy-D-sorbitol unit, and two end-attached lipophilic alkyl chains, have been synthesized by palladium-catalyzed cross-coupling reactions as the key steps. The thermotropic liquid crystalline behavior of these compounds was investigated by polarized light microscopy, differential scanning calorimetry (DSC), and X-ray scattering. We investigated the mode of self-organization as a function of the length and position of the lateral polar chain and the length of the terminal alkyl chains. Depending on the size of the polar and lipophilic segments, a series of unusual liquid crystalline phases was detected. In three of these phases, the space is divided into three distinct periodic subspaces. In addition to a hexagonal channeled layer phase (ChL(hex)) consisting of layers that are penetrated by polar columns, there are also two honeycomb-like network structures formed by square (Col(squ)/p4mm) or pentagonal cylinders (Col(squ)/p4gm). The cylinder walls consist of the terphenyl units fused by columns of alkyl chains, and the interior contains the polar side chains. In addition, a hexagonal columnar phase was observed in which the polar columns are organized in a continuum of terphenyls and alkyl chains with an organization of the terphenyl cores tangentially around the columns with the long axis perpendicular to the columns. For one compound, a reversal of birefringence was observed, which is explained by a reorientation of the terphenyl cores. The addition of protic solvents induces lamellar phases.

Carbohydrate Conformation↗
PubMed2005

Separation and quantitative analysis of coumarin compounds from Angelica dahurica (Fisch. ex Hoffm) Benth. et Hook. f by pressurized capillary electrochromatography.

A pressurized capillary electrochromatography (pCEC) method with post-column detection cell has been developed for the therapeutically important coumarins from Angelica dahurica extract. The separation of five major coumarins (xanthotoxol, osthenol, imperatorin, oxypeucedanin hydrate, byakangelicin) was optimized with respect to composition of the mobile phase, ionic strength of buffers, pH, and applied voltage. Baseline separation was achieved for the five coumarins in less than 25 min using a mobile phase of methanol-acetonitrile-phosphate buffer (pH 4.8; 15 mM) (22.5:15:62.5, v/v/v). The method showed satisfactory retention time and peak area repeatability with the first use of post-column detection cell in the pCEC instrument. Comparing to capillary high performance liquid chromatography (capillary HPLC) and conventional high performance liquid chromatography (HPLC), higher column efficiency, and shorter analysis time were achieved in pCEC. The five coumarins in the extract samples representing different stages of traditional extraction of A. dahurica were also quantitatively analyzed by pCEC. The calibration curves were linear in the range 37-129, 36-126, 12-41, 88-306, 20-69 microg/ml of the standard solutions containing the five coumarins with correlation coefficients between 0.9976 and 0.9994.

Calibration↗
PubMed2005

Fezl regulates the differentiation and axon targeting of layer 5 subcortical projection neurons in cerebral cortex.

During the development of the cerebral cortex, progenitor cells produce neurons that migrate to laminar positions appropriate for their birth dates, adopt specific neuronal identities, and form appropriate local and long-distance axonal connections. Here, we report that forebrain embryonic zinc-finger-like protein (Fezl), a putative zinc-finger transcriptional repressor, is required for the differentiation of projection neurons in cortical layer 5. In Fezl-deficient mice, these neurons display molecular, morphological, and axonal targeting defects. The corticospinal tract was absent in Fezl(-/-) mice, corticotectal and pontine projections were severely reduced, and Fezl-expressing neurons formed aberrant axonal projections. The expression of many molecular markers for deep-layer neurons was reduced or absent in the Fezl(-/-) cerebral cortex. Most strikingly, Ctip2, a transcription factor required for the formation of the corticospinal tract, was not expressed in the Fezl-deficient cortex. These results suggest that Fezl regulates the differentiation of layer 5 subcortical projection neurons.

Animals↗
PubMed2005

Natural abundance of Sb and Sc in pristine groundwaters, Springwater Township, Ontario, Canada, and implications for tracing contamination from landfill leachates.

Using ICP-SMS and the clean lab methods and procedures developed for determining trace element concentrations in polar snow and ice, a lower limit of detection (LOD) of 30 pg l(-1) for Sb and 5 pg l(-1) for Sc was achieved, allowing the natural abundances of Sb and Sc to be measured in pristine groundwaters. Water samples were collected from natural flows and wells between Elmvale and Wyevale in Springwater Township, Ontario, Canada. The water in this region is derived from chemical reactions between meteoric fluids and the Quaternary sediments which cover the bedrock (dolomitic limestone) to depths of more than 100 m. The chemical composition of these waters (pH 8) is primarily a reflection of reactions between the percolating fluids with calcite and dolomite. The maximum concentration of Sb was 5.0 ng l(-1), and the average of all samples collected was 2.2 +/- 1.2 ng l(-1) (n = 34). The average concentration of Sc was 8.6 +/- 4.7 ng l(-1) (n = 28). The paucity of published Sb concentration data available for comparison is probably because most of the analytical methods commonly used to date, including GFAAS, HG-AAS, HG-AFS, INAA, and ICP-QMS, have lower limits of detection which are inadequate for reliably determining the natural abundance of Sb in many uncontaminated groundwaters. Also, the measurement of extremely low concentrations of Sb requires extra care to avoid possible contamination. Given the extensive use of Sb in plastics, we show that some of the containers used to collect and store samples, and for handling and preparing samples for chemical analyses, may be important sources of contamination in the laboratory. The Sb and Sc concentrations reported here should serve as reference values for this region, against which contamination by various human impacts in future could be compared.

Antimony↗
PubMed2005

Thoron levels in traditional Chinese residential dwellings.

A survey on radon (222Rn), thoron (220Rn) and its decay products (220RnD) was conducted in Chinese traditional residential dwellings constructed with loam bricks or soil wall. The activity concentrations in 164 dwellings under investigation were 72.4+/-59.2 (arithmetic mean, AM) and 57.5+/-2.0 Bq m-3 (geometric mean, GM) for 222Rn, and 318+/-368 and 162+/-3.7 Bq m-3 for 220Rn, respectively. For 220RnD, 67 dwellings were studied. The AM of the 220RnD equilibrium equivalent concentration was 3.8+/-3.3 Bq m-3 with a maximum value of 15.8 Bq m-3. On the basis of these results, the average annual effective doses to the local residents due to radon and thoron exposure were 1.44-4.62 mSv. Thoron contributes 12.9-56.6% to the total doses. Preliminary results show that there is a relation between 220RnD in air and 232Th in soil. The correlation factors of outdoor and indoor were 0.88 and 0.40. The 232Th activity content of Chinese soil is estimated to be about two times the world average. The traditional residential dwellings with soil construction are still common in China. Further investigations on the 220Rn level in these dwelling with the aim of dose reduction are proposed.

Air Pollution, Indoor↗
PubMed2005

Lithogenic, oceanic and anthropogenic sources of atmospheric Sb to a maritime blanket bog, Myrarnar, Faroe Islands.

Antimony concentrations were measured in a core collected from Myrarnar, a blanket bog on the Faroe Islands which has been accumulating peat for more than six thousand years. The vertical distribution of Sb indicates that it has been supplied to the peat exclusively from the atmosphere. Despite the proximity to the ocean, the contribution of Sb to the peat from marine aerosols amounts to less than ca. 10% of the natural inputs. Although the peat core contains four notable layers of volcanic ash originating from Iceland, these have not contributed significantly to the Sb inventory. However, the distribution of Sb closely resembles that of Pb, with most of the Sb found in peats dating from the industrial period. Peat samples dating from the Roman Period are not only contaminated with Pb, but also with Sb. Lead is known to be immobile in peat bogs, and in Europe has been derived predominantly from industrial sources for thousands of years. The correlation between Sb and Pb in the peat core from the Faroe Islands supports the hypothesis that Sb is also effectively immobile in peat, and that ombrotrophic bogs are faithful archives of atmospheric Sb deposition. The data presented here also reinforces the view that natural Sb inputs during the past two centuries are dwarfed by industrial inputs, and that human activities have affected the atmospheric Sb cycle to a comparable extent to that of Pb. The natural rate of atmospheric Sb deposition recorded by the peat core (0.33 microg m(-2) year(-1)) is remarkably similar to the value obtained from a Swiss peat bog (Etang de la Gruère) in the samples dating from ca. 6000 to 9000 years ago (0.35 microg m(-2) year(-1)) which suggests that the background rates obtained from the peat cores have broader validity. Consistent with previous work, the data from the Faroe Islands suggests that the natural flux of Sb to the global atmosphere may have been overestimated by a factor of ten, and that the influence of human activities has been underestimated to the same extent.

Antimony↗
PubMed2005

The HSP90 family of genes in the human genome: insights into their divergence and evolution.

HSP90 proteins are important molecular chaperones. Transcriptome and genome analyses revealed that the human HSP90 family includes 17 genes that fall into four classes. A standardized nomenclature for each of these genes is presented here. Classes HSP90AA, HSP90AB, HSP90B, and TRAP contain 7, 6, 3, and 1 genes, respectively. HSP90AA genes mapped onto chromosomes 1, 3, 4, and 11; HSP90AB genes mapped onto 3, 4, 6, 13 and 15; HSP90B genes mapped onto 1, 12, and 15; and the TRAP1 gene mapped onto 16. Six genes, HSP90AA1, HSP90AA2, HSP90N, HSP90AB1, HSP90B1 and TRAP1, were recognized as functional, and the remaining 11 genes were considered putative pseudogenes. Amino acid polymorphic variants were detected for genes HSP90AA1, HSP90AA2, HSP90AB1, HSP90B1, and TRAP1. The structures of these genes and the functional motifs and polymorphic variants of their proteins were documented and the features and functions of their proteins were discussed. Phylogenetic analyses based on both nucleotide and protein data demonstrated that HSP90(AA+AB+B) formed a monophyletic clade, whereas TRAP is a relatively distant paralogue of this clade.

Amino Acid Sequence↗
PubMed2005

Correction for direction-dependent distortions in diffusion tensor imaging using matched magnetic field maps.

Diffusion tensor imaging (DTI) has seen increased usage in clinical and basic science research in the past decade. By assessing the water diffusion anisotropy within biological tissues, e.g. brain, researchers can infer different fiber structures important for neural pathways. A typical DTI data set contains at least one base image and six diffusion-weighted images along non-collinear encoding directions. The resultant images can then be combined to derive the three principal axes of the diffusion tensor and their respective cross terms, which can in turn be used to compute fractional anisotropy (FA) maps, apparent diffusion coefficient (ADC) maps, and to construct axonal fibers. The above operations all assume that DTI images along different diffusion-weighting directions for the same brain register to each other without spatial distortions. This assumption is generally false, as the large diffusion-weighting gradients would usually induce eddy currents to generate diffusion-weighting direction-dependent field gradients, leading to mis-registration within the DTI data set. Traditional methods for correcting magnetic field-induced distortions do not usually take into account these direction-dependent eddy currents unique for DTI, and they are usually time-consuming because multiple phase images need to be acquired. In this report, we describe our theory and implementation of an efficient and effective method to correct for the main field and eddy current-induced direction-dependent distortions for DTI images under a unified framework to facilitate the daily practice of DTI acquisitions.

Anisotropy↗
PubMed2005

Gene targeting using a promoterless gene trap vector ("targeted trapping") is an efficient method to mutate a large fraction of genes.

A powerful tool for postgenomic analysis of mammalian gene function is gene targeting in mouse ES cells. We report that homologous recombination using a promoterless gene trap vector ("targeting trapping") yields targeting frequencies averaging above 50%, a significant increase compared with current approaches. These high frequencies appear to be due to the stringency of selection with promoterless constructs, because most random insertions are silent and eliminated by drug selection. The promoterless design requires that the targeted gene be expressed in ES cells at levels exceeding a certain threshold (which we estimate to be approximately 1% of the transferrin receptor gene expression level, for the secretory trap vector used here). Analysis of 127 genes that had been trapped by random (nontargeted) gene trapping with the same vector shows that virtually all are expressed in ES cells above this threshold, suggesting that targeted and random trapping share similar requirements for expression levels. In a random sampling of 130 genes encoding secretory proteins, about half were expressed above threshold, suggesting that about half of all secretory genes are accessible by either targeted or random gene trapping. The simplicity and high efficiency of the method facilitate systematic targeting of a large fraction of the genome by individual investigators and large-scale consortia alike.

Animals↗
PubMed2005

[Application of keyhole approach in operation of intracranial aneurysms].

OBJECTIVE: To explore the operative technique and evaluate the effect of intracranial aneurysms via keyhole approach. METHODS: Fifty-six intracranial aneurysm patients, 23 with anterior communicating artery (AcomA) aneurysm, 29 with posterior communicating artery (PcomA) aneurysm, and 4 with internal carotid artery-posterior communicating artery aneurysm, totally with 58 lesions, were treated by microsurgery, via supraorbital keyhole approach in 22 cases, pterional approach in 18, and transorbital approach in 16. Adjuvant endoscopy was used in 33 patients. RESULTS: Fifty-eight lesions of aneurysm were clipped in all the patients and no one died. No approach-related severe complication occurred. Bilateral PcomA aneurysms in 2 cases were clipped via unilateral keyhole approach. CONCLUSION: It is workable to treat intracranial aneurysms via keyhole approach. Keyhole approach not only reduces the operation-related trauma and shorten the operation time, but also obtains ideal results.

Adult↗
PubMed2005

Characterization of retinal damage in the episcleral vein cauterization rat glaucoma model.

Episcleral vein cauterization (EVC) is used in rats to generate a glaucoma model with high intraocular pressure (IOP). The long-term retinal damage in this glaucoma model, however, has not been accurately quantified. We report the location and amount of retinal ganglion cell (RGC) damage caused by (EVC) induced IOP elevation in two rat strains. IOP was raised in one eye of Wistar (N = 5) and Brown-Norway(B-N)(N = 7) rats by EVC and monitored monthly until IOP in contralateral eyes equalized at 5 months post-surgery. Animals were maintained for 3.5-4.5 additional months. B-N rats (N = 7) that had no EVC served as controls for this strain. Scotopic flash ERGs were recorded at baseline and just prior to euthanasia. Automated counts of all retrogradely labeled RGCs in retinal flat-mounts were determined and compared between contralateral eyes. RGC density maps were constructed and RGC size distribution was determined. Oscillatory potentials in the group of eyes which had elevated IOP were decreased at the time of euthanasia, when IOP had returned to normal. The group of normal B-N rats had similar RGC counts between contralateral eyes. In the experimental group the mean number of RGCs was not significantly different between control and experimental eyes, but 1 of 5 Wistar and 2 of 7 B-N experimental eyes had at least 30% fewer RGCs than contralateral control eyes. Total retinal area in B-N experimental eyes was higher compared to contralateral eyes. Cumulative IOP exposure of the experimental eyes was modestly correlated with RGC loss while oscillatory potentials appeared to be inversely related to RGC loss. In retinas with extensive (> 30% RGC loss) but not complete damage, smaller cells were preserved better than larger ones. The above results indicate that RGC loss in both Wistar and B-N strains is variable after a prolonged elevation of IOP via EVC. Such variability despite equivalent IOP levels and ERG abnormalities, suggests unknown factors that can protect IOP-stressed RGCs. Identification and enhancement of such factors could prove useful for glaucoma therapy.

Animals↗
PubMed2005

Strategies for managing the insufficiency of the proximal landing zone during endovascular thoracic aortic repair.

BACKGROUND: The insufficiency of the proximal landing zone (PLZ) is a frequent factor challenging the applicability and efficacy of endovascular repair (EVR) for thoracic aortic disorders. This study discusses two strategies for conquering this challenge. METHODS: Ten patients underwent EVR for thoracic aortic diseases during a one-year period ending June 30, 2004. Nine patients had DeBakey type III dissecting aortic aneurysm (DAA), and one had descending thoracic aortic aneurysm (DTAA). The PLZ, defined as the distance from the origin of the left subclavian artery (LSA) to the primary entry tear of the dissection or to the proximal aspect of DTAA, was less than 15 mm in all instances. EVR with intentional coverage of the LSA without any supportive bypass was employed in 6 patients with DAA, and the preliminary right-left carotid and left carotid-subclavian bypass combined with EVR in the DTAA and other 3 DAA cases. RESULTS: Technical success was achieved in all the patients. The patient with DTAA died from hemispheric cerebral infarction and subsequent multiple system organ failure following an uneventful recovery from the cervical reconstruction performed 1 week previously. In cases receiving the EVR with intentional coverage of the LSA, in two patients dizziness occurred, which noticeably resolved after intravenous administration of mannitol for 4 to 5 days, and a drop in blood pressure of the left arm was noted in all the cases, but remained clinically silent. No neurological deficits or limb ischaemia developed perioperatively or during the followup, ranging from 3 to 12 months, and complete thrombosis of the thoracic aortic false lumen was revealed on CT at 3 months in the 9 patients with DAA. CONCLUSIONS: Both the intentional bypass absent coverage of the LSA and the adjunctive surgical bypass appear to be feasible and effective in managing the insufficiency of the PLZ during the endovascular thoracic aortic repair.

Adult↗
PubMed2005

[Strategies for handling the insufficiency of the proximal landing zone during endovascular thoracic aortic repair].

OBJECTIVE: To discuss two strategies for handling the insufficiency of the proximal landing zone (PLZ) during endovascular thoracic aortic repair. METHODS: Ten patients underwent endovascular repair (EVR) in the thoracic aorta in one year. Nine patients had DeBakey type III aortic dissection aneurysm (ADA), and one had descending thoracic aortic aneurysm (DTAA). The PLZ, defined as the distance from the origin of the left subclavian artery (LSA) to the primary entry tear of the dissection or the proximal aspect of DTAA, was measured less than 15 mm in all instances by contrast-enhanced CT scan and digital subtraction angiography. The preliminary carotid-carotid and left carotid-subclavian bypass combined with EVR was employed in the DTAA and 3 ADA cases, and the EVR with the intentional coverage of the LSA without the preliminary bypass in the rest 6 ADA patients. RESULTS: The technical success was achieved in all instances. The case of DTAA died of the hemispheric cerebral infarction and subsequent multiple system organ failure, albeit the uneventful recovery from the prior cervical reconstruction. Dizziness occurred in 2 patients (ADA) after the EVR with the intentional bypass-absent coverage of the LSA, but noticeably resolved after the intravenous administration of mannitol for 4 to 5 days. No neurological deficits or limb ischemia developed perioperatively or during the follow-up range from 3 to 12 months. And complete thrombosis of the thoracic aortic false lumen and enlargement of the true lumen were revealed on CT at 3 months in all 9 patients with ADA. CONCLUSIONS: Both the adjunctive surgical bypass and the intentional bypass-absent coverage of the left subclavian artery appear feasible in handling the insufficiency of the proximal landing zone during the endovascular thoracic aortic repair. It can expand the EVR applicability in management of DeBakey type III ADAs and DTAAs.

Adult↗