Biomedical subjects

Y Cheng

Publications and source records attributed to Y Cheng.

At least 199 records · Page 11Linked to original sources

PubMed1997

Alzheimer-type of pathological changes in Chinese.

There has been no previous description of the pathological features of Alzheimer's disease and little description of Alzheimer-type changes in Chinese brains. In this study, we examined the brains of 17 cases of Alzheimer's disease and concurrently 95 consecutive autopsy cases of non-demented patients aged above 60. Six standard regions of the brains were stained for beta-amyloid immunostaining, Bielschowsky and Bodian. Neuritic plaques, neurofibrillary tangles and diffuse plaques were quantified as per mm2. The Alzheimer's disease brains exhibited a marked increase of neurodegenerative changes over the non-demented brains. Plaque counts were similar to those proposed by Khachaturian (1985; Arch. Neurol. 42: 1097-1105) and CERAD, although the distribution of tangles was more variable with some regions of the neocortex containing few or no tangles. For the non-demented brains, overall neuritic plaques were seen in 31% and neurofibrillary tangles were seen in 42% of cases, with the overall plaque score being 1.8 per mm2 and tangle score being 0.7 per mm2. No age-dependent variation of plaque count and tangle count could be demonstrated in this group of elderly brains. Comparison with similar studies of Caucasians suggests that neuritic plaques and neurofibrillary tangles were less frequently encountered in aging Chinese brains than among the western populations.

Aged↗

PubMed1997

Ethanol-induced cell death by lipid peroxidation in PC12 cells.

Free radical generation is hypothesized to be the cause of alcohol-induced tissue injury. Using fluorescent cis-parinaric acid and TBARS, lipid peroxidation was shown to be increased in the presence of trace amounts of free ferrous ion in PC12 cells. This increase in lipid peroxidation was enhanced by ethanol in a dose dependent manner and also correlated with loss of cell viability, as measured by increased release of lactate dehydrogenase (LDH). Resveratrol, a potent antioxidant, had a protective effect against lipid peroxidation and cell death. These findings strongly suggest that ethanol-induced tissue injury and cell death is a free radical mediated process, and may be important in alcohol-related premature aging and other degenerative diseases.

Animals↗

PubMed1997

Clinical findings for patients with Lyme borreliosis caused by Borrelia burgdorferi sensu lato with genotypic and phenotypic similarities to strain 25015.

In the course of performing culture isolation of Borrelia burgdorferi sensu lato for the diagnosis of Lyme borreliosis in Slovenia, we encountered nine patients who were infected with atypical strains. Molecular analyses of these strains suggested that they were more closely related to the North American tick isolate, strain 25015 (which belongs to the DN127 genomic group of B. burgdorferi sensu lato), than they were to the three species (B. burgdorferi sensu stricto, Borrelia garinii, and Borrelia afzelii) hitherto found to be associated with European Lyme borreliosis. Review of the case histories of these patients revealed some atypical clinical features and variability in clinical presentation. In this study, we present the clinical findings for these patients and discuss their significance for the diagnosis of Lyme borreliosis. The DN127 genomic group shares with B. burgdorferi sensu stricto the distinction of being present in both the Old and New Worlds.

Adult↗

PubMed1997

Molecular subtyping of Borrelia burgdorferi sensu lato isolates from five patients with solitary lymphocytoma.

Solitary lymphocytoma is a rare cutaneous manifestation of Lyme borreliosis that has been reported almost exclusively from Europe. This suggests that its etiologic agent may be absent or extremely rare on the North American continent. All three species of B. burgdorferi sensu lato known to be associated with human Lyme borreliosis (B. burgdorferi sensu stricto, B. garinii, and B. afzelii have been isolated in Europe, whereas only B. burgdorferi sensu stricto has been found in North America. This suggests that either B. garinii or B. afzelii might be the etiologic agent of borrelial lymphocytoma. To investigate this hypothesis we characterized five strains of B. burgdorferi sensu lato isolated from lymphocytoma lesions of patients residing in Slovenia. The methods used included: large restriction fragment pattern analysis of restriction enzyme MluI-digested genomic DNA, plasmid profiling, protein profiling, ribotyping using 5S, 16S, and 23S rDNA probes, and polymerase chain reaction amplification of the rrf (5S)-rrl (23S) intergenic spacer region. Molecular subtyping showed that four of the five isolates belonged to the species B. afzelii; however, this species is the predominant patient isolate in Slovenia and, therefore, may not represent a preferential association with lymphocytoma. The fifth isolate appeared to be most closely related to the DN127 genomic group of organisms. Further characterization of the isolate revealed that it possessed a unique molecular "fingerprint." The results not only show that borrelial lymphocytoma can be caused by B. afzelii but also demonstrate an association with another genomic group of B. burgdorferi sensu lato that is present in North America as well.

Adult↗

PubMed1997

High-resolution fluorescent imaging does not reveal a distinct atrioventricular nodal anterior input channel (fast pathway) in the rabbit heart during sinus rhythm.

INTRODUCTION: We sought to determine the precise pathways of engagement of the AV node during sinus rhythm. METHODS AND RESULTS: Langendorff-perfused rabbit hearts were stained with 20 microM of the voltage-sensitive dye di-4-ANEPPS. Preparations containing the right atrium, sinoatrial (SA) and AV nodes, and interatrial septum were subsequently dissected and mapped in vitro using a 16 X 16 photodiode array with an adjustable resolution of 150 to 750 microns per diode. Motion artifacts were eliminated by using 15 mM 2,3-butanedione monoxime (BDM). Activation time-points were defined as (-dF/dt)max' where F = fluorescence. Isochronal maps of activation were plotted using the triangulation method. In all preparations, spontaneous activation began at the SA node, rapidly spread along the crista terminalis (CrT), entered the AV nodal region via the posterior "slow" pathway, and retrogradely spread to the septal region with a smaller conduction velocity compared to that along the CrT. Collision of anterograde and retrograde wavefronts was frequently observed in the mid-septum. Notably, there was no evidence for the presence of a distinct anterior entrance into the AV node. CONCLUSIONS: Fast pathway conduction during sinus rhythm results from a broad posterior wavefront that envelops the AV node with subsequent retrograde atrial septal activation.

Action Potentials↗

PubMed1997

Effects of 2,3-butanedione monoxime on atrial-atrioventricular nodal conduction in isolated rabbit heart.

INTRODUCTION: 2,3-Butanedione monoxime (BDM) has been found to reversibly block cardiac contraction, without blocking electrical conduction. This study characterizes the dose-dependent effects of BDM on the conduction through the atrioventricular node (AVN) of rabbit heart. METHODS AND RESULTS: Thirteen isolated atrial-AVN preparations were used in control, during and after exposure to 5, 10, and 20 mM BDM. Anterograde and retrograde pacing protocols were used to obtain the Wenckebach cycle length, effective and functional refractory periods of the AVN, index of AVN conduction delay (the area under the AVN conduction curve), as well as index of intra-atrial conduction delay between the AVN inputs. Compared to control, 5 and 10 mM BDM produced either shortening or no effect on all of the above parameters except a slight (6% and 14%, respectively) increase in the intra-atrial delay. At 20 mM, BDM produced a further increase in the intra-atrial delay (up to 50%) as well as in the retrograde AVN conduction delay (up to 16%), while the characteristics of the anterograde conduction were still improved. The effects of perfusion with BDM on these parameters were reversible after washout. CONCLUSIONS: Aside from its known effect as an electromechanical uncoupler, BDM reversibly altered some of the electrical responses of the AVN. Most of these alterations, however, did not impede but rather improved AVN conduction. Since a dose of 10 mM is sufficient to fully eliminate undesirable motion, BDM should be considered a safe and valuable tool in AVN studies in vitro requiring a mechanically quiescent preparation.

Action Potentials↗

PubMed1997

Puumala hantavirus genome in patients with nephropathia epidemica: correlation of PCR positivity with HLA haplotype and link to viral sequences in local rodents.

Reverse transcription-PCR was used to analyze specimens from 20 Finnish nephropathia epidemica (NE) patients hospitalized during the period from October 1994 to January 1995. Blood and/or urine sediment specimens from seven patients were found to be positive for the genome sequences of Puumala hantavirus (PUU). PCR positivity of the specimens from the patients correlated well with the HLA-DRB1*0301 and HLA B8 alleles, which previously were shown to associate with severe courses of NE. Genetic analysis of the partial M-and/or S-segment sequences obtained from three severely ill NE patients revealed three PUU strains related to but distinct from previously reported strains from Finland. The M-segment sequence of PUU from bank voles trapped near the probable site of infection for one of the patients showed 98.2% identity to that of the PUU strain obtained from the patient, suggesting a link between wild-type PUU from the natural focus and the NE case. The S-segment sequences from the patient and the bank voles, however, showed substantially lower identity (95.8%). As this difference in diversity for M and S genes (1.8 and 4.2%) is atypical for PUU genetic drift, one possibility is that the strain acquired at the putative place of infection is a reassortant one.

Adult↗

PubMed1997

Cell culture adaptation of Puumala hantavirus changes the infectivity for its natural reservoir, Clethrionomys glareolus, and leads to accumulation of mutants with altered genomic RNA S segment.

This paper reports the establishment of a model for hantavirus host adaptation. Wild-type (wt) (bank vole-passaged) and Vero E6 cell-cultured variants of Puumala virus strain Kazan were analyzed for their virologic and genetic properties. The wt variant was well adapted for reproduction in bank voles but not in cell culture, while the Vero E6 strains replicated to much higher efficiency in cell culture but did not reproducibly infect bank voles. Comparison of the consensus sequences of the respective viral genomes revealed no differences in the coding region of the S gene. However, the noncoding regions of the S gene were found to be different at positions 26 and 1577. In one additional and independent adaptation experiment, all analyzed cDNA clones from the Vero E6-adapted variant were found to carry substitutions at position 1580 of the S segment, just 3 nucleotides downstream of the mutation observed in the first adaptation. No differences were found in the consensus sequences of the entire M segments from the wt and the Vero E6-adapted variants. The results indicated different impacts of the S and the M genomic segments for the adaptation process and selective advantages for the variants that carried altered noncoding sequences of the S segment. We conclude that the isolation in cell culture resulted in a phenotypically and genotypically altered hantavirus.

Adaptation, Physiological↗

PubMed1997

A two year prospective study to compare culture and polymerase chain reaction amplification for the detection and diagnosis of Lyme borreliosis.

AIM: To compare polymerase chain reaction (PCR) amplification of borrelial DNA and culture isolation of spirochaetes for the diagnosis of Lyme borreliosis by direct detection of Borrelia burgdorferi sensu lato in patients with erythema migrans and acrodermatitis chronica atrophicans lesions. METHODS: Skin biopsy specimens from erythema migrans and acrodermatitis chronica atrophicans lesions were subdivided and tested by PCR amplification assay and culture using two artificial growth media, Barbour-Stoenner-Kelly II (BSK II) and modified Kelly-Pettenkofer (MKP). Five classes of lesions were studied: typical erythema migrans, spontaneously resolved erythema migrans, atypical/partially treated erythema migrans, typical acrodermatitis chronica atrophicans, and atypical/partially treated acrodermatitis chronica atrophicans. RESULTS: For both erythema migrans and acrodermatitis chronica atrophicans lesions, the most sensitive detection method was MKP culture. PCR was less sensitive than MKP culture, but more sensitive than BSK II culture. Results for 758 typical erythema migrans specimens showed positivity rates of 36% for MKP, 25% for PCR, and 24% for BSK II. Differences were statistically significant. The overall positivity rate for all three methods combined was 54%, but few specimens (6%) were positive by all three methods. Examination of multiple erythema migrans lesions from the same patient increased the diagnostic yield. These findings, and similar results for acrodermatitis chronica atrophicans lesions, suggest that the distribution of spirochaetes in skin biopsies is not homogeneous. CONCLUSIONS: Although possessing the potential to provide a rapid diagnosis, PCR is not more sensitive than culture for the direct detection of borrelia. Spirochaetes appear to be unevenly distributed throughout biopsy specimens, suggesting that diagnosis of Lyme borreliosis by direct detection of the causative agent in skin lesions in vulnerable to sample bias.

Acrodermatitis↗

PubMed1997

Mechanism of atrioventricular nodal facilitation in the rabbit heart: role of the distal AV node.

We investigated whether atrioventricular (AV) nodal facilitation is the result of distal AV nodal action potential shortening. Atrial and bundle of His (H) electrograms and microelectrode recordings from proximal and distal AV nodal cells were analyzed in eight superfused rabbit AV node preparations in response to two pacing protocols. In the facilitation protocol, an atrial extrastimulus (A3) was preceded by an atrial impulse (A2) introduced 300, 200, 150, or 125 ms after 30 basic beats (A1). The preexcitation protocol differed from the facilitation protocol by the addition of a premature His depolarization (h2) such that the H1-h2 interval was shorter than the H1-H2 interval. Conduction curves (A3-H3 vs. H2-A3, h2-A3, and A2-A3 intervals) were constructed. Facilitation was demonstrated in all preparations when H2-A3 was used (P = 0.02) but not in the A2-A3 format. Compared with facilitation at the same A1-A2 intervals, preexcitation, despite shortening the distal cellular action potential duration, resulted in longer A3-H3 delays (P = 0.002), shorter A2-A3 intervals, and depression of the proximal nodal cellular response. Thus facilitation does not result from altered distal AV nodal characteristics and instead is a manifestation of an uncontrolled pacing protocol-dependent modulation of proximal AV nodal function.

Action Potentials↗

PubMed1997

Mechanism of atrioventricular nodal facilitation in rabbit heart: role of proximal AV node.

The phenomenon of atrioventricular (AV) nodal "facilitation," described in traditional "black box"-functional studies, implies enhanced AV nodal dromotropic function. We investigated the role of atrial prematurities in the modulation of the nodal cellular responses in the mechanism of AV nodal facilitation. Atrial and His (H) bundle electrograms and microelectrode recordings from proximal AV nodal cells were analyzed in 15 superfused rabbit AV node preparations. The pacing protocol consisted of 30 basic beats (S1; coupling interval S1-S1 = 300 ms) followed by a facilitating prematurity (S2; coupling intervals S1-S2 of 300, 200, 150, and 130 ms) followed by the test beat (S3; coupling interval S2-S3 scanned in 5-ms steps). Conduction curves (S2-H2 vs. S1-S2, S3-H3 vs. S2-S3, and S3-H3 vs. H2-S3) were constructed. Facilitation (i.e., shortening of S3-H3 when S1-S2 was shortened) was demonstrated in all preparations using the H2-S3 (P < 0.001) but not the S2-S3 format. Microelectrode recordings revealed a causal relationship between the improved proximal AV nodal cellular responses in facilitation and the prolonged S2-S3 interval. There was no evidence for enhanced nodal dromotropic function directly resulting from the introduction of the facilitating beats. Thus facilitation is based on inherent cycle-length-dependent properties of the AV node during application of a complex pacing protocol and primarily reflects the uncontrolled modulation of the proximal cellular response.

Animals↗

PubMed1997

[Analysis of 58 cases of the usage of B'-scan in clinical forensic medical examination].

This article analysis the usage of B'-Scan in some special cases in clinical forensic medicine, such as the injuries of eyeball, urinosexual organs (include kidney, ureter, urinary bladder, urethra penis, scrotum, testis, uterus et al) liver-gallbladder-spleen, thyreoid and parathyreoid, and the position and course of the scars in the deep of the body. The result indicates that the B'-Scan can be used to display not only the morphological changes, such as the positions, characteristics and degrees of the injuries, but also the function when to be used combining with the Doppler.

Adolescent↗

PubMed1997

Production and purification of Bordetella pertussis toxin.

Pertussis toxin (PT) is the major protective antigen of acellular pertussis vaccine (aP). We have established an optimal culture condition for the growth of B. pertussis and the production of PT in a laboratory scale fermentor. It was found that when the dissolved oxygen in medium was supplied with pure oxygen instead of air, the yield of PT was dramatically increased (i.e. from 2-3 mg/l using air to 8-10 mg/l using pure oxygen). PT was purified by affinity chromatography using hydroxyapatite and fetuin-sepharose columns. SDS-PAGE analysis and CHO cell clustering test showed that the purified PT was comparable to the reference PT in purity and biological activity. The purified PT could be detoxified by formaldehyde (d-PT). The results of CHO cell clustering neutralization assay and ELISA showed that the antibody induced by d-PT in mice was comparable to that induced by PT contained in a commercial DTaP. These results indicated that the immunogenicity of our d-PT was retained after the purification and detoxification procedures.

Animals↗

PubMed1997

[A primary study on antagonizing effects of anti-snake venom Chinese herbs on endothelin-1 and sarafotoxin 6b].

Some anti-snake venom Chinese herbs were used to test the antagonizing effect on ET-1 and S6b. Oral administration has shown that both the water and alcohol extracts from Cissus assamica and Aristolochia fordiana, and the water extracts from Desmodium microphyllum, Cynanthum paniculatum and Polygonum cillinerve are very helpful in reducing the acute death caused by ET-1 and S6b(i.v.), while the extracts from Cissus assamica, Aristolochia fordiana and Cynanthum paniculatum can dilate the vasoconstriction by ET-1 in a dose dependent manner. Pharmacodynamic parameters have shown that the potencies of alcohol extracts from Cissus assamica and Aristolochia fordiana are greater than that of Cynanthum paniculatum. These data suggest that traditional anti-snake venom herbs have antagonizing effects on ET-1.

Animals↗

PubMed1997

[Separation of soybean agglutinin by hydrophobic-interaction chromatography].

The soybean agglutinin (SBA) was separated with hydrophobic-interaction chromatography (HIC) in this work. HIC of the crude lectin extract of SBA was performed on Phenyl-Sepharose CL-4B column, 10 cm x 2.5 cm i.d., at a flow-rate of 1.0 mL/min. A 20 mL sample of the crude extract was applied to the column previously equilibrated with the buffer, 0.01 mol/L PBS containing ammonium sulfate (60% of saturation concentration). The column was eluted with the starting buffer, then with the buffer containing 30% saturation of ammonium sulfate, and finally with 0.01 mol/L PBS. Fractions were detected by UV absorbance at 280 nm and assayed for hemagglutinating activity. The results show that the purification-fold was as high as 35 and the recovery of activity was 100%.

Chromatography↗

PubMed1997

[Study on cross-linked capillary columns coated with polyphenylenesiloxane].

A new type of cross-linked capillary column coated with polyphenylenesiloxane which possesses phenylene in the siloxane main chain has been described in this paper. The cross-linking of polyphenylenesiloxane was performed in situ by the induction of DCUP. The structure of polyphenylenesiloxane is as followed: [structure: see text] The repeatabilities and solvent inextractabilities of the column preparations were investigated. For decane and 1-octanol, the values of n/L and k' at 120 degrees C were 2800-3100 and 1.0-1.3, 2400-2800 and 5.0-6.0, respectively. The k' values of the columns scarcely changed after eluting with methylene chloride and pentane. The base-acid property was studied by analyzing 2,6-dimethylphenol and 2,6-dimethylaniline. Besides, in comparision with OV-17 and OV-25, the McReynolds' constants of the cross-linked column were also determined. The advantages of this kind of column are summarized as (1) easy preparation; (2) heat stability improved; and (3) good selectivity for the organic compounds which contain halogen, nitro group or phenol.

English Abstract↗

PubMed1997

[Study of the effects of pulse magnetic fields on hemorrheology of human body].

The results show that middle shear specific viscosity and reductive viscosity (P<0.05), low shear specific viscosity and reductive viscosity of whole blood (P<0.01) decreased significantly in experimental group after 9-day of pulse magnetic fields, comparing with control group, high shear specific viscosity, low shear reductive viscosity (P<0.05) and middle and low shear specific viscosity (P<0.01) of whole blood in experimental group were lower after exposed than before exposed to pulse magnetic fields. The results suggest that the pulse magnetic fields may reduce specific and reductive viscosity of whole blood in human body.

Blood Viscosity↗

PubMed1997

[Investigation on absorption edge and Ep, Eg of tetragonal crystal system SBN].

In this paper, the station of the absorption edge of Sr0.63 Ba0.37 Nb2O6 single Crystal is measured with experimental studies. The absorption coefficient is calculated with transimitting curve. The absorption edge below 3.5eV is attributable to indirect transition by studing the alpha1/2-hv curve. The phonon energy Ep and the energy gap Eg are ascertained.

English Abstract↗