Biomedical subjects

Yan Jin

Publications and source records attributed to Yan Jin.

At least 55 records · Page 3Linked to original sources

PubMed2006

[Effects of ectomesenchymal stem cells on hematopoiesis after total body irradiation].

OBJECTIVE: To investigate the effects of ectomesenchymal stem cells on hematopoiesis after total body irradiation in rats. METHODS: The primary ectomesenchymal stem cells were isolated from E11.5 SD fetal mandibular processes by 2.5 g/L trypsin and cultured with DMEM/F12. The morphology and growth rate were observed by inverted microscope. Eighty SD male rats randomly divided into ectomesenchymal stem cells group (n = 20), fibroblast group (n = 20), saline group (n = 20) and control group (n = 20), the first three groups were irradiated with 60Co gamma rays at 6. 0 Gy. The number of their bone marrow nucleated cells was counted after 4 weeks; the forming ability of colony-forming unit-granulocyte macrophage (CFU-GM) and histopathology of bone marrow were also observed. RESULTS: The cultured cells displayed monolayer growth and fibroblast-like with 2-4 processes. The ectomesenchymal stem cells could increase the number of bone marrow nucleated cells and peripheral blood white cell count, and improve the forming ability of CFU-GM. After 4 weeks of transplantation, the number of the peripheral blood white cells in group A was more than that in groups B and C (P < 0.05), the contents of Hb in groups A and D was significantly higher than those in groups B and C (P < 0.05). After 4 weeks, the bone marrow nucleated cells in group A were significant more than those in groups B and C (P < 0.01); CFU-GM in groups A and D was higher than that in groups B and C (P < 0.01). CONCLUSION: Ectomesenchymal stem cells have characteristics of stem cells. It may improve hematopoiesis recovery of irradiated rats.

Animals↗

PubMed2006

[Effects of ADAM28 AS-ODN on proliferation and AKPase of HDFCs].

PURPOSE: To study the effects of ADAM28 antisense oligodeoxynucleotide (AS-ODN) on proliferation of human dental follicle cells (HDFCs) and activity of alkaline phosphatase (AKPase). METHODS: Cell culture, gene transfection, MTT chromatometry and enzyme kinetics methods were used to detect the possible mechanisms of ADAM28 AS-ODN on proliferation, differentiation of HDFCs and effect of the activity of AKPase. Statistical significance was assessed by multiple comparison (q test, SNK) in one-way analysis of variance (ANOVA). RESULTS: ADAM28 AS-ODN was transfected into HDFCs successfully. MTT and AKPase activity assays indicated that cell proliferation and AKPase activity of ADAM28 AS-ODN group were significantly lower than those of S-ODN and vacuity control group (P<0.01). MTT assay revealed P value between AS-ODN and S-ODN, blank control group was 0.0002, 0.0001 respectively, P<0.01; AKPase assay showed P value between AS-ODN and S-ODN, vacuity control group was 0.0007, 0.0003 respectively, P<0.01. ADAM28 AS-ODN could inhibit the proliferation and AKPase activity of HDFCs significantly. CONCLUSIONS: ADAM28 may promote proliferation and differentiation of HDFCs by participating in Notch signal pathway.

ADAM Proteins↗

PubMed2006

[Aqueous oxidation of SO2 with microbial method].

The desulfurizations in dilute sulfuric acid solution, acidic ferric solution, acidic ferrous solution, microbial solution (Thiobacillus ferrooridans) and microbial culture medium solution were conducted to discuss biodesulfurization mechanism. The effect of Fe3+ concentration, Fe2+ concentration, SO2 concentration and temperature on biodesulfurization was examined on SO4(2-) concentration in the solution. Biodesulfurization has two ways: direct oxidation and indirect oxidation. In direct oxidation, Thiobacillus ferrooxridans oxidize S(IV) to S(VI). In indirect oxidation, Thiobacillus ferrooxidans can fast transform Fe2+ to Fe3+ in acidic conditions and then increase aqueous catalytic oxidation capacity of Fe3+ on SO2. It shows that indirect oxidation is the dominant way in biodesulfurization process. The desulfurization efficiency increase with concentration of Fe3+ or Fe2+ in the range of 0-1.2 g/L. Thiobacillus ferrooxidans enforce oxidation of SO2 in Fe3+ /Fe2+ system. The removal of SO2 decrease as concentration of SO2 increase, however, concentrations of SO4(2-) in the solution do not vary much in different inlet concentrations of SO2. Temperature has important effect on biodesulfurization. The optimal operative temperature range is 30-40 degrees C.

Ferric Compounds↗

PubMed2006

Utilization rates for surgical procedures in rural and urban Canada.

OBJECTIVE: To investigate whether utilization rates of common surgical procedures are different between urban and rural Canadians in 2 provinces and to examine whether these rates are influenced by the presence and scope of local surgical programs and by the availability of different physician providers. METHODS: Utilization rates for 8 common surgical procedures (appendectomy, carpal tunnel release, closed hip fracture repair, rectal cancer surgery, joint replacement, thyroidectomy, unilateral or bilateral inguinal herniorrhaphy, and cholecystectomy) were identified in rural Alberta and rural Northern Ontario from hospital discharge records. Rural populations were characterized by 3 types of communities, based on availability of local physician and diagnostic resources. Travel time for consultations and surgery were estimated. Age-sex-adjusted rates, their standard errors, and 95% confidence intervals (CIs) were calculated for the purpose of comparisons among residents' locations using the method of direct standardization. To test a possible association between travel times and utilization rates, hierarchical linear and nonlinear modelling was used to analyze a 2-level model, with patients nested within rural hospital catchment areas in the province of Alberta. RESULTS: Utilization rates for appendectomy, cholecystectomy and carpal tunnel release are significantly greater for rural populations compared with urban in both Alberta and Northern Ontario. Rural Northern Ontario had higher rates of utilization than rural Alberta for carpal tunnel release and cholecystectomy (p < 0.01) and closed hip fracture repair (p < 0.05). No statistical differences between the provinces were noted for the remaining procedures. No difference in utilization rates was found between the 3 types of rural centres. The modelling found a significant association between travel time and use for only one procedure--carpal tunnel release. Patients who had to travel < or =1 hour had a 13% higher surgery rate. CONCLUSION: Rates of utilization were higher in rural areas for procedures where greater surgical variability is known to exist. These higher rural rates were not influenced by either the presence or scope of local surgical programs nor by the differences in providers. There was no difference in rates for procedures where previous research has shown little variability.

Alberta↗

PubMed2006

[Expression map of immune-related genes on PBMCs in familial clustering patients with chronic virus hepatitis B].

AIM: To investigate peripheral blood mononuclear cells (PBMCs) immune-related gene expression profile in patients with chronic virus hepatitis B(CHB) by oligonucleotide gene array technique. METHODS: PBMCs were collected from the members of a family of clustering hepatitis B virus (HBV) infection including 5 CHB patients and 4 healthy spouses and RNA prepared from PBMCs was hybridized to high-density oligonucleotide arrays(HG-U133A 2.0 Human Gene Chips, Affymetrix), covering the expression of 22 000 human ESTs. Primary scanned image was analyzed with DNT software package. RESULTS: Out of the 22 000 ESTs, 24 different immune-related genes were identified. Among the 24 genes, 7 genes showed increased expression and 17 genes showed decreased expression in CHB compared with those in healthy spouses. The up-regulated genes were mainly associated with adaptive immunity, while the down-regulated genes were associated with innate immunity. CONCLUSION: Our findings suggest that HBV infection alters a broad range of immunity genes expression and innate immunity-associated genes are important in the defense against HBV chronic infection.

Down-Regulation↗

PubMed2006

[The reconstruction of bioengineer active corneal stroma and its biocompatibility study].

This paper aims to explore the biocompatibility of bioengineer active corneal stroma (BACS), as the biological carrier for cornea reconstruction, to provide the basis for future study on clinic application. The cells and immunogenic components of cornea stroma were removed through different extract methods. A complex of functional corneal stroma cells and acellular corneal stroma was used to reconstruct BACS. Their morphological characteristics and ultrastructures were observed with transmission electron microscope. The complex was grafted into interlamellar stromal pockets. Cells were labeled by BrdU to examine the survival and conversion after grafting. The cells could survive and proliferate in acellular corneal stroma. All the nuclei of the corneal stromal cells showed positive labeling with BrdU in the BACS. After 4 weeks, BACS became transparent; after 8 weeks, the bioengineer active cornea stroma was fully reconstructed.

Animals↗

PubMed2005

A MAPK gene from Dead Sea fungus confers stress tolerance to lithium salt and freezing-thawing: Prospects for saline agriculture.

The Dead Sea is one of the most saline lakes on earth ( approximately 340 g/liter salinity) and is approximately 10 times saltier than the oceans. Eurotium herbariorum, a common fungal species, was isolated from its water. EhHOG gene, encoding a mitogen-activated protein kinase (MAPK) that plays an essential role in the osmoregulatory pathway in yeast and many other eukaryotes, was isolated from E. herbariorum. The deduced amino acid sequences of EhHOG indicated high similarity with homologous genes from Aspergillus nidulans, Saccharomyces cerevisiae, and Schizosaccharomyces pombe and contained a TGY motif for phosphorylation by MAPK kinase. When EhHOG was expressed in S. cerevisiae hog1Delta mutant, the growth and aberrant morphology of hog1Delta mutant was restored under high osmotic stress condition. Moreover, intracellular glycerol content in the transformant increased to a much higher level than that in the mutant during salt-stress situations. hog1Delta mutant complemented by EhHOG outperformed the wild type or had higher genetic fitness under high Li(+) and freezing-thawing conditions. The present study revealed the putative presence of a high-osmolarity glycerol response (HOG) pathway in E. herbariorum and the significance of EhHOG in osmotic regulation, heat stress, freeze stress, and oxidative stress. The Dead Sea is becoming increasingly more saline while the fungi living in it evolutionarily adapt to its high-saline environment, particularly with the extraordinarily high Li(+) concentration. The Dead Sea is potentially an excellent model for studies of evolution under extreme environments and is an important gene pool for future agricultural genetic engineering prospects.

Agriculture↗

PubMed2005

Removal and inactivation of waterborne viruses using zerovalent iron.

A daunting challenge facing the water industry and regulators is how to simultaneously control microbial pathogens, residual disinfectant, and disinfection byproducts in drinking water, and to do so at an acceptable cost. Of the different pathogens, viruses are especially problematic due to their small size, high mobility, and resistance to chlorination and filtration. In the past decade, zerovalent iron has been used to treat a wide variety of organic and inorganic contaminants from groundwater. However, iron has not been tested against biological agents. This study examined the effectiveness of commercial zerovalent iron to remove two viruses, phiX174 and MS-2, from water. Removal of these viruses by iron granules in batch reactors was first-order, and the rate was likely controlled by external mass transfer. Most of the viruses removed from solution were either inactivated or irreversibly adsorbed to iron. In a flow-through column containing zerovalent iron (with 20 min of iron contact time), the removal efficiency for both viruses was 4-log in an initial pulse test, and over 5-log in the second pulse test after passage of 320 pore volumes of artificial groundwater. We assume that the improved efficiency was due to continuous formation of new iron (oxyhydr)oxides which served as virus adsorption sites. To our knowledge, this is the first demonstration of biological agent removal from water by zerovalent iron. Results of this study suggest zerovalent iron may be potentially useful for disinfecting drinking water and wastewater, thereby reducing our dependence on chlorine and reducing the formation of disinfection byproducts.

Ions↗

PubMed2005

Release of bioactive BMP from dextran-derived microspheres: a novel delivery concept.

Recent developments of biotechnology have produced a great variety of protein and bioactive drugs. For these drugs to be used therapeutically, suitable drug delivery systems have become increasingly essential. Dextran-derived biomaterials have been considered to be compatible matrices for protein and bioactive drugs because of their hydrophilic properties and ability to control drug dissolution and permeability. A novel class of dextran-glycidylmethacrylate (Dex-GMA)/poly(ethylene glycol) (PEG) microspheres were designed and synthesized by polymerization of Dex-GMA emulsified in an aqueous PEG solution. Dex-GMA was prepared by substituting the hydroxyl groups in Dex by GMA. The drug loading and in vitro drug release was evaluated by routine procedure and the biological activity of BMP-loaded microspheres was studied by experimental cytology methods. Recombinant human bone morphogenetic protein-2 (rhBMP-2) were entrapped in dextran-derived microspheres quantitatively and with full preservation of their biological activity. In vitro release kinetics indicated that dextran-derived microspheres could retain rhBMP-2 in a variable manner depending on the preparation and degradation of the microspheres. The release profiles of rhBMP-2 from microspheres as a function of time showed that rhBMP-2 releasing kinetics in vitro fitted to first-order and Higuchi equations. The release profile in vitro was in accord with two phases kinetics law and more than 60% drug were released during 20 days. Cytology studies showed rhBMP-2 microspheres have good biological effects on cultured periodontal ligament cells, and could achieve a longer action time than concentration of rhBMP-2 solution. These properties make those microspheres interesting osteo-conductive BMP carriers, allowing to decrease the amount of implanted factor required for tissue regeneration.

Alkaline Phosphatase↗

PubMed2005

Hepatocyte nuclear factor-3alpha binding at P sequences of the human growth hormone locus is associated with pituitary repressor function.

The human GH family consists of five genes, including the placental chorionic somatomammotropins (CS), within a single locus on chromosome 17. Based on nuclease sensitivity, the entire GH/CS locus is accessible in pituitary chromatin, yet only GH-N is expressed. Previously, we reported a P sequence element (263P) capable of repressing placental CS-A promoter activity in transfected pituitary (GC) cells, and our data indicated a possible role for nuclear factor-1 (NF-1) and regulatory factor X1 in this repression. In this study we show the formation of two independent pituitary complexes in vitro: a repressor complex containing NF-1 and a nonfunctional complex containing regulatory factor X1. In vitro repressor function is stabilized by the presence of P sequence element C (PSE-C), downstream of the previously characterized PSE-A and PSE-B. Repressor function is also dependent on an intact Pit-1 binding site in the CS-A promoter. EMSAs with PSE-C reveal binding of the hepatocyte nuclear factor-3/forkhead (HNF-3/fkh) family of transcription factors in rat pituitary GC cells. This observation is extended to human pituitary tissue, where HNF-3alpha's association with P sequences is confirmed by chromatin immunoprecipitation. Furthermore, protein-protein interactions between HNF-3alpha and NF-1 family members are demonstrated. These results identify HNF-3alpha as an additional member of the pituitary P sequence regulatory complex, implicating it in tissue-specific expression of the human GH/CS family.

Animals↗

PubMed2005

Retention and transport of amphiphilic colloids under unsaturated flow conditions: effect of particle size and surface property.

The purpose of this study was to examine the mechanisms responsible for deposition and transport of amphiphilic colloids with a wide range of particle sizes (20-420 nm) through porous media. A series of saturated and unsaturated column experiments were conducted using amphiphilic latex microspheres and a hydrophilic silica colloid. We found that the amphiphilic latex particles were retained to a greater extentthan the hydrophilic silica colloid in unsaturated media. This was attributed to colloidal attachment atthe air-water interface due mainly to hydrophobic interactions. We also found that dependence of colloid retention on particle size was nonlinear. There existed a fraction of colloids with greater mobility than other fractions, which we referred to as the most mobile colloids. As particle size increased from 20 to 420 nm, colloid deposition rate first decreased to reach a minimum value at --100 nm then increased, indicating that different retention mechanisms were involved. We showed that conducting saturated transport experiments and analysis using filtration theory may be an effective approach for determining the most mobile colloid size(s) in porous media, perhaps even for unsaturated flow conditions. This study highlights the importance of including size effect and surface properties when predicting concentrations and fluxes of amphiphilic colloids or colloid-bound amphiphilic and hydrophobic contaminants in the subsurface environment.

Colloids↗

PubMed2005

Preparation and biological characteristics of recombinant human bone morphogenetic protein-2-loaded dextran-co-gelatin hydrogel microspheres, in vitro and in vivo studies.

Hydrogels are based on hydrophilic polymers which are cross-linked to prevent dissolution in water. Because hydrogels can contain large amounts of water, they are interesting devices for the delivery of protein drugs. In this contribution, biodegradable dextran-co-gelatin hydrogel microspheres (DG-MPs) are described which are based on physical interactions and are particularly suitable for the controlled delivery of pharmaceutically active proteins. The unique feature of this preparation system is that the hydrogel microsphere formation takes place in an all-aqueous solution, by which the use of organic solvents is avoided. We investigated the preparation and biological activities of recombinant human bone morphogenetic protein-2 (rhBMP2)-loaded dextran-co-gelatin hydrogel microspheres (rhBMP2-DG-MPs), which aimed to keep rhBMP2's biological activity and to achieve a long-term sustained release of rhBMP2. The microspheres' average diameter was about 20-40 microm and rhBMP2 release in vitro could be maintained for >10 days. Cytology studies showed that using rhBMP2-DG-MPs could promote the proliferation and osteoblastic differentiation of periodontal ligament cells better than using rhBMP2 aqueous solution. By a freeze-drying method, rhBMP2-DG-MPs could be adhered in chitosan membranes for guided tissue regeneration use, namely functionalized membranes. To evaluate bone regeneration induced by rhBMP2-DG-MPs, an animal experiment with canine class III furcation defects was adopted and the results indicated that using rhBMP2-DG-MPs incorporating scaffolds and functionalized membranes could gain more periodontal tissue regeneration than using scaffolds and general membranes soaked with concentrated rhBMP2 aqueous solution. Therefore, those studies demonstrate the potential of DG-MPs in the sustained delivery of low dosages of rhBMP2 to periodontal defects.

Animals↗

PubMed2005

Crystal structure of a bacterial homologue of Na+/Cl--dependent neurotransmitter transporters.

Na+/Cl--dependent transporters terminate synaptic transmission by using electrochemical gradients to drive the uptake of neurotransmitters, including the biogenic amines, from the synapse to the cytoplasm of neurons and glia. These transporters are the targets of therapeutic and illicit compounds, and their dysfunction has been implicated in multiple diseases of the nervous system. Here we present the crystal structure of a bacterial homologue of these transporters from Aquifex aeolicus, in complex with its substrate, leucine, and two sodium ions. The protein core consists of the first ten of twelve transmembrane segments, with segments 1-5 related to 6-10 by a pseudo-two-fold axis in the membrane plane. Leucine and the sodium ions are bound within the protein core, halfway across the membrane bilayer, in an occluded site devoid of water. The leucine and ion binding sites are defined by partially unwound transmembrane helices, with main-chain atoms and helix dipoles having key roles in substrate and ion binding. The structure reveals the architecture of this important class of transporter, illuminates the determinants of substrate binding and ion selectivity, and defines the external and internal gates.

Amino Acid Sequence↗

PubMed2005

DNA cleavage by copper-ATCUN complexes. Factors influencing cleavage mechanism and linearization of dsDNA.

The reactivity of two [peptide-Cu] complexes ([GGH-Cu](-) and [KGHK-Cu](+)) toward DNA cleavage has been quantitatively investigated. Neither complex promoted hydrolytic cleavage, but efficient oxidative cleavage was observed in the presence of a mild reducing agent (ascorbate) and dioxygen. Studies with scavengers of ROS confirmed hydrogen peroxide to be an obligatory diffusible intermediate. While oxidative cleavage of DNA was observed for Cu(2+)(aq) under the conditions used, the kinetics of cleavage and reaction products/pathway were distinct from those displayed by [peptide-Cu] complexes. DNA cleavage chemistry is mediated by the H(2)O-dependent pathway following C-4'H abstraction from the minor groove. Such a cleavage path also provides a ready explanation for the linearization reaction promoted by [KGHK-Cu](+). Kinetic activities and reaction pathways are compared to published results on other chemical nucleases. Both [peptide-Cu] complexes were found to display second-order kinetics, with rate constants k(2) approximately 39 and 93 M(-1) s(-1) for [GGH-Cu](-) and [KGHK-Cu](+), respectively. Neither complex displayed enzyme-like saturation behavior, consistent with the relatively low binding affinity and residence time expected for association with dsDNA, and the absence of a prereaction complex. However, the intrinsic activity of each is superior to other catalyst systems, as determined from relative k(2) or k(cat)/K(m) values. Linearization of DNA was observed for [KGHK-Cu](+) relative to [GGH-Cu](-), consistent with the increased positive charge and longer residency time on dsDNA.

Copper↗

PubMed2005

[Biocompatibility study on tendon mixed extraction of bovine collagen for periodontal tissue engineering].

OBJECTIVE: To study the biocompatibility of tendon mixed extraction of bovine collagen (tMEBC) and to explore the feasibility of using the three-dimensional framework as periodontal tissue engineering scaffold. METHODS: After being prepared, the tMEBC were cultured with the P4-P6 of human periodontal ligament fibroblasts (HPDLFs) in vitro. Three-dimensional framework was prepared from bovine tendon. The P4-P6 of HPDLFs (with an initial density of 5 x 10(6) cells/ml) were cultured in vitro. Cell attachment and proliferation were measured by cell counting 1 day, 3, 5, and 10 days after cell seeding. Histological examination was performed with light microscope and scanning electron microscope 5 and 10 days after cell seeding. RESULTS: Porous structure, which supported the proliferation and attachment of HPDLFs, was found in tMEBC. The density of cell increased from 0.556 x 10(4) cells/ml 24 hours after cell seeding to 3.944 X 10(4) cells/mI 10 days after seeding. Light and scanning electron microscope examination indicated that HPDLFs were attached and extended on the three-dimensional scaffolds and were well embedded in the newly formed tissue matrix. CONCLUSION: tMEBC has good biocompatibility with the HPDLFs, and can be used as scaffold for cell transplantation in periodontal tissue engineering.

Animals↗

PubMed2005

CYP2D6 genotype, antidepressant use, and tamoxifen metabolism during adjuvant breast cancer treatment.

BACKGROUND: The efficacy of tamoxifen therapy for the treatment of breast cancer varies widely among individuals. Plasma concentrations of the active tamoxifen metabolite endoxifen are associated with the cytochrome P450 (CYP) 2D6 genotype. We examined the effects of concomitant use of selective serotonin reuptake inhibitor antidepressants, which are CYP2D6 enzyme inhibitors commonly prescribed to treat hot flashes in women who take tamoxifen, and genotypes for genes that encode tamoxifen-metabolizing enzymes on plasma concentrations of tamoxifen and its metabolites. METHODS: Eighty patients with newly diagnosed with breast cancer who were beginning tamoxifen therapy (20 mg/day orally), 24 of whom were taking CYP2D6 inhibitors, were genotyped for common alleles of the CYP2D6, CYP2C9, CYP3A5, and sulfotransferase (SULT) 1A1 genes. Plasma concentrations of tamoxifen and its metabolites were measured after 1 and 4 months of tamoxifen therapy. Differences in plasma concentrations of tamoxifen and its metabolites between genotype groups were analyzed by the Wilcoxon rank sum test. All statistical tests were two-sided. RESULTS: Among all women, plasma endoxifen concentrations after 4 months of tamoxifen therapy were statistically significantly lower in subjects with a CYP2D6 homozygous variant genotype (20.0 nM, 95% confidence interval [CI] = 11.1 to 28.9 nM) or a heterozygous genotype (43.1 nM, 95% CI = 33.3 to 52.9 nM) than in those with a homozygous wild-type genotype (78.0 nM, 95%CI = 65.9 to 90.1 nM) (both P = .003). Among subjects who carried a homozygous wild-type genotype, the mean plasma endoxifen concentration for those who were using CYP2D6 inhibitors was 58% lower than that for those who were not (38.6 nM versus 91.4 nM, difference = -52.8 nM, 95% CI = -86.1 to -19.5 nM, P = .0025). The plasma endoxifen concentration was slightly reduced in women taking venlafaxine, a weak inhibitor of CYP2D6, whereas the plasma endoxifen concentration was reduced substantially in subjects who took paroxetine (a potent inhibitor of CYP2D6). Genetic variations of CYP2C9, CYP3A5, or SULT1A1 had no statistically significant associations with plasma concentrations of tamoxifen or its metabolites. CONCLUSION: Interactions between CYP2D6 polymorphisms and coadministered antidepressants and other drugs that are CYP2D6 inhibitors may be associated with altered tamoxifen activity.

Adult↗

PubMed2005

Narrow QRS tachycardia with ventriculoatrial dissociation mediated by a left fasciculoventricular fiber.

A 30-year-old man presented with narrow QRS tachycardia. The intracardiac electrocardiogram showed an atrial-HIS (AH) interval of 75 msec and a HIS-ventricular (HV) interval of 44 msec during baseline. Atrial incremental pacing revealed HV shortening, with apparent incomplete right bundle branch block (RBBB) morphology without QRS complex axis deviation. The induced tachycardia exhibited several QRS morphologies: a narrow QRS, complete RBBB and complete left bundle branch block (LBBB) morphology. Spontaneous conversion of the QRS pattern from wide to narrow was observed. The cycle length of the tachycardia was significantly shortened (from 316 to 272 ms) from LBBB morphology to narrow QRS complex. The atrial activation was dissociated from the ventricular activation during all tachycardias. Each QRS complex during tachycardia was preceded by a HIS deflection and HV interval was 35 ms, which was shorter than that of sinus rhythm. HIS deflection was earlier than right bundle potential during all kinds of tachycardia. This tachycardia is most likely mediated by a left fasciculoventricular fiber which connects the HIS bundle below the atrioventricular node to the myocardial tissue of the left ventricle. The HIS-Purkinje system is used as an antegrade conduction limb and the fasciculoventricular fiber as a retrograde limb in the tachycardia circuit.

Adult↗

PubMed2005

Association between physician specialty and volumes of treated patients and mortality among patients hospitalized for newly diagnosed heart failure.

PURPOSE: To assess the effects of hospital care by a specialist or nonspecialist physician, and by volume of treated patients, on mortality among hospitalized patients with newly diagnosed heart failure. METHODS: Data describing heart failure patients in Alberta, Canada, from April 1, 1994, to March 31, 2000, were extracted from hospital abstracts and analyzed using hierarchical regression, with adjustment for patient demographic characteristics, comorbid conditions, physician volume, physician specialty, and hospital volume. RESULTS: There were 16,162 hospital discharges for heart failure. Nonspecialist physicians were predominantly in the two lowest-volume quartiles (93%) and specialists were predominantly in the two highest-volume quartiles (68%). Considering the effects of volume alone and after adjustment for comorbidity, for each 10 additional hospital patients treated by a physician, the odds ratio for in-hospital mortality was 0.97 (95% confidence interval [CI]: 0.95 to 0.98), and the odds ratio for 1-year mortality was 0.99 (95% CI: 0.98 to 0.999). In analyses that considered both volume and specialty, the odds of in-hospital mortality decreased by 4% for each 10 additional in-hospital patients treated by a physician (odds ratio [OR] = 0.96; 95% CI: 0.95 to 0.98). In these same analyses, the odds ratio for in-hospital mortality was 1.32 (95% CI: 1.13 to 1.53) for general practitioners with specialist consultation and 1.32 (95% CI: 1.08 to 1.61) for specialists compared with general practitioners without specialist consultations. At 1 year, mortality was not associated significantly with the volume of in-hospital patients treated, or with the specialty of the treating physician. CONCLUSION: Treatment by high-volume physicians during hospitalization for newly diagnosed heart failure was associated with a decrease in mortality, but these benefits did not persist at 1 year. The increased mortality noted in patients treated by specialists may be due to residual confounding or unmeasured comorbidity.

Adult↗