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Biomedical subjects

H Yuan

Publications and source records attributed to H Yuan.

At least 127 records · Page 7Linked to original sources
PubMed1998

[The animal experiments and clinical trial of impeller pump used as left ventricular or biventricular assist device].

The authors' impeller pump as a left ventricular or biventricular assist device was evaluated in animal experiments and clinical trial. Three calves survived over 6 weeks in left ventricular assist experiments and neither blood damage nor organ dysfunction of the animals was detected. In clinical trial, the pump supported both the greater and lesser circulation of a 6-year-old child with trilogy of Fallot and low output syndrome after open heart surgery. In 43 hours the pump worked properly. The pump weighing 240 g can perform either in pulsatile or in nonpulsatile mode. In pulsatile pumping, the impeller changes its rotating speed periodically by introducing a square wave form voltage into the motor coil.

Animals↗
PubMed1997

Genetic characterization of vif, vpr, and vpu sequences from long-term survivors of human immunodeficiency virus type 1 infection.

The identification of HIV-1-infected individuals who remain asymptomatic despite prolonged infection presents a unique opportunity to understand virologic and host factors involved in the pathogenesis of AIDS. We have previously identified 10 long-term survivors (LTS) who are clinically healthy and immunologically normal despite 13 to 15 years of HIV-1 infection. In this study, we examined three accessory genes of HIV-1, vif, vpr, and vpu, in these LTS. A total of 52 vif, 54 vpr, and 55 vpu nucleotide sequences were obtained from the peripheral blood mononuclear cells of these patients. Analysis of these sequences revealed no gross deletions or insertions. Most of the clones were full-length with an intact open reading frame. Phylogenetic analyses of the vif, vpr, and vpu sequences from the LTS suggested that the HIV-1 strains found in the study subjects are not significantly different from those found in patients with AIDS and that the viruses in the LTS are unlikely to share a common genetic origin. Furthermore, a similar degree of overall genetic diversity between viruses from the LTS and AIDS patients suggests that there is unlikely a significant correlation between the degree of genetic diversity and the rate of disease development. Factors other than genetic divergence, such as viral load and phenotype, are likely to impact more on disease status.

Adult↗
PubMed1997

Osteogenic responses to extraskeletally implanted synthetic porous calcium phosphate ceramics: an early stage histomorphological study in dogs.

In this experiment, synthetic porous calcium phosphate ceramics (hydroxyapatite-tricalcium phosphate) were prepared and implanted in dorsal muscles of dogs. The purpose was to study the biological processes prior to and during the morphogenesis of bone in extraskeletally implanted porous calcium phosphate ceramics. Specimens were harvested after implantation for 7, 15, 30, 45, 60, 90 and 120 days. Decalcified and undecalcified sections were prepared for alkaline phosphatase (ALP) histochemical localization and comparative histological analysis. The results show that bone morphogenesis in the pore regions of the extraskeletally implanted ceramics follows a complex process involving clot formation, vascular invasion, granulation-like tissue formation, polymorphic cell aggregation, osteoblast differentiation and bone formation. The characteristic feature preceding bone formation was polymorphic cell aggregation on the pore inner surface and near the invading capillaries or small venules. These cells were of various sizes and shapes, and some of them were positive for ALP activity. ALP-positive cell aggregates were more numerous where capillaries or venules were close to the pore inner surface. Osteoblast differentiation occurred within the cell clusters aggregated on the pore inner surface and bone matrix was secreted in direct contact with the ceramics. During bone formation, capillaries or small venules were always found close to the developing fronts of the osseous nidi. It is suggested that those cells which first appeared near the invading vasculature, the cells which aggregated on the pore inner surface and those cells which finally differentiated into osteoblasts may be interrelated in some way.

Journal Article↗
PubMed1997

Primary structure and functional expression of heavy- and light-chain variable region genes of a monoclonal antibody specific for human fibrin.

The immunoglobulin heavy- and light-chain variable region (VH and VK) genes were isolated from 8E5 hybridoma cells, which secreted monoclonal antibody against human fibrin by RT-PCR. An expression vector pOPE51-8E5 was constructed for the recombinant VH-VK scFv expression. The primary sequence of the variable regions was determined. Expression product was found in the periplasmic space and inclusion bodies by SDS-PAGE and immunoblotting. It was a 30 KDa single chain fragment (scFv) with the antigen-binding specificity of the parental monoclonal antibody. A light chain shuffling with an unspecific VL did not result in a loss of fibrin binding specificity.

Amino Acid Sequence↗
PubMed1997

Identification of a replication-competent pathogenic human immunodeficiency virus type 1 with a duplication in the TCF-1alpha region but lacking NF-kappaB binding sites.

Multiple human immunodeficiency virus type 1 (HIV-1) sequences with deletions of NF-kappaB binding sites at both the 5' and 3' long terminal repeats (LTRs) were identified in serial samples collected from an infected individual. The effect of this deletion on the level of transcription was studied by transient transfection of an LTR-driven luciferase reporter gene and by infection with a full-length recombinant HIV-1 containing a luciferase reporter (HIVHXBluc). Detectable levels of gene expression were found in both systems, in the presence or absence of the viral transactivator Tat. Interestingly, a duplication of a putative TCF-1alpha motif was found in place of the NF-kappaB elements in these viruses. Higher transcriptional activity was observed with HXBLTR (NF-kappaB intact) than with the patient's LTR (NF-kappaB deleted), suggesting that the NF-kappaB binding sites may promote optimal levels of viral gene transcription. The ability of these viruses with NF-kappaB deleted to replicate and cause substantial decline in CD4 cell counts demonstrates that the NF-kappaB binding sites are not absolutely required for viral replication or pathogenicity in vivo. These results are consistent with the notion that the HIV-1 LTR possesses functional redundancy which allows it to interact with multiple transcription factors, thereby ensuring viral replication in a variety of cell types.

Base Sequence↗
PubMed1997

Genotypic and phenotypic characterization of long terminal repeat sequences from long-term survivors of human immunodeficiency virus type 1 infection.

Human immunodeficiency virus type 1 (HIV-1)-infected individuals who remain asymptomatic despite prolonged infection present a unique opportunity to understand virologic and immunologic factors involved in the pathogenesis of AIDS. We have previously identified a group of long-term survivors (LTS) who are clinically healthy and immunologically normal despite 13 to 15 years of HIV-1 infection. In this study, we examined the 5' long terminal repeat (5' LTR) sequences in eight of these LTS. A total of 29 nucleotide sequences were obtained from their peripheral blood mononuclear cells (PBMC). Analysis of these sequences revealed no gross deletions within the 5' LTR. Seven of the eight subjects shared nearly identical consensus sequences in the binding sites for NF-kappaB, Sp1, and the viral trans-activator Tat. In multiple samples from one individual (Pt 5), however, G-to-A hypermutations were found throughout the entire region, suggesting a genetically defective 5' LTR. The effects of the observed genetic variations on LTR transcription were studied by transient transfection of an LTR-driven luciferase reporter gene and by infection with a full-length recombinant HIV-1 containing a luciferase reporter (HIVHXBLTRluc). A wide range of basal and Tat-induced transcriptional activities was found among the 5' LTR from seven of the eight LTS in both transfected 293 cells and donor PBMC, suggesting a functionally intact 5' LTR in these individuals. It is therefore unlikely that defects in the 5' LTR are the underlying explanation for the benign clinical course associated with these seven individuals. However, functional abnormalities were found in the LTR from Pt 5 in directing both heterologous and viral gene expression, providing a possible genetic explanation for the low viral load and prolonged asymptomatic state of this individual. Last, a similar overall degree of genetic diversity was found among viruses from the LTS compared to those from patients with AIDS, reinforcing the notion that a strong correlation between the degree of genetic diversity and the rate of disease progression is unlikely.

Base Sequence↗
PubMed1997

Partitioning of lung tissue response and inhomogeneous airway constriction at the airway opening.

During a bronchial challenge, much of the observed response of lung tissues is an artifactual consequence of inhomogeneous airway constriction. Inhomogeneities, in the sense of time constant inequalities, are an inherently linear phenomenon. Conversely, if lung tissues respond to a bronchoagonist, they become more nonlinear. On the basis of these distinct responses, we present an approach to separate real tissue changes from airway inhomogeneities. We developed a lung model that includes airway inhomogeneities in the form of a continuous distribution of airway resistances and nonlinear viscoelastic tissues. Because time domain data are dominated by nonlinearities, whereas frequency domain data are most sensitive to inhomogeneities, we apply a combined time-frequency domain identification scheme. This model was tested with simulated data from a morphometrically based airway model mimicking gross peripheral airway inhomogeneities and shown capable of recovering all tissue parameters to within 15% error. Application to our previously measured data suggests that in dogs during histamine infusion 1) the distribution of airway resistances increases widely and 2) lung tissues do respond but less so than previously reported. This approach, then, is unique in its ability to differentiate between airway and tissue responses to an agonist from a single broadband measurement made at the airway opening.

Airway Resistance↗
PubMed1997

Dynamic properties of lung parenchyma: mechanical contributions of fiber network and interstitial cells.

We investigated the contributions of the connective tissue fiber network and interstitial cells to parenchymal mechanics in a surfactant-free system. In eight strips of uniform dimension from guinea pig lung, we assessed the storage (G') and loss (G") moduli by using pseudo-random length oscillations containing a specially designed set of seven frequencies from 0.07 to 2.4 Hz at baseline, during methacholine (MCh) challenge, and after death of the interstitial cells. Measurements were made at mean forces of 0.5 and 1 g and strain amplitudes of 5, 10, and 15% and were repeated 12 h later in the same, but nonviable samples. The results were interpreted using a linear viscoelastic model incorporating both tissue damping (G) and stiffness (H). The G' and G" increased linearly with the logarithm of frequency, and both G and H showed negative strain amplitude and positive mean force dependence. After MCh challenge, the G' and G" spectra were elevated uniformly, and G and H increased by < 15%. Tissue stiffness, strain amplitude, and mean force dependence were virtually identical in the viable and nonviable samples. The G and hence energy dissipation were approximately 10% smaller in the nonviable samples due to absence of actin-myosin cross-bridge cycling. We conclude that the connective tissue network may also dominate parenchymal mechanics in the intact lung, which can be influenced by the tone or contraction of interstitial cells.

Animals↗
PubMed1997

[Survey of smoking and human health in Guangdong province].

As part of the national plan in China, 28,979 residents or farmers were surveyed in 1991 in Guangdong province to investigate the relation between smoking and human health. The results showed that the total smoking rate was 40.2%, 58.8% was for male and 1.2% was for female. 56.4% was in city and 38.7% was in rural area. The beginning smoking age was 15-16 years old (5.5%). 8.5% smokers started smoking after 25 years old. Smoking can increase risk of diseases. The incidence of chronic bronchitis, hypertension, gastric ulcer and pulmonary TB in smoking group were significantly higher than that in non-smoking group. No difference was found in the symptoms of panting, cough and phlegm between the two groups. To control smoking is one of the important measures for human health.

Adolescent↗
PubMed1997

Observation on electromyogram changes in 93 cases of peripheral facial paralysis treated by point-through-point acupuncture.

Bioelectricity of the affected muscles at acute stage, recovery stage and sequel state in 93 cases of peripheral facial paralysis was observed with EMG. Pathological potential or motor potential was found to be reduced to varying degrees in all the affected muscles. After treatment by point-through-point acupuncture, myodynamia recovered fairly rapidly, EMG showed obvious changes, pathological potential decreased, and the normal motor unit potential increased remarkably. Comparative analysis of EMG before and after acupuncture indicated that point-through-point acupuncture had an obvious therapeutic effect on the disease. It was also very significant that EMG was used in diagnosing various stages of peripheral facial paralysis, evaluation of prognosis and guidance in clinical treatment.

Acupuncture Points↗
PubMed1997

116 cases of coronary angina pectoris treated with powder composed of radix ginseng, radix notoginseng and succinum.

116 cases of coronary angina pectoris were treated with a powder composed of Radix Ginseng, Radix Notoginseng and Succinum, which was an empirical prescription of Dr. Yue Meizhong ([symbol: see text]), and compared with patients treated Fufang Danshen Tablet (a compound prescription of Radix Salviae Miltiorrhizae) as the control group. Results indicated that the curative effects and ECG in the treated group were better than that in the control group (P < 0.01), so were improvement of general symptoms, physical strength as well as changes of lipid metabolism and microcirculation of nail fold.

Adult↗
PubMed1997

[Supra-aortic arch esophageal mucosa-gastric wall anastomosis with oblique stomach invagination through esophageal bed for patients with esophageal carcinoma undergone esophagectomy].

OBJECTIVE: To reduce impairement of pulmonary function by thoracic stomach and other postoperative complications. METHODS: One hundred eighteen patients with esophageal carcinoma were treated with supra-aortic arch esophageal mucosa-gastric wall anastomosis with oblique stomach invagination through esophageal bed. RESULTS: No anastomotic leakage or gastroesophageal reflux occurred. The incidence of anastomotic stricture was 2.5%, that of operative mortality was 0.9%. Cardiopulmonary complications occurred in 11.0%. CONCLUSION: The procedure may keep the normal anatomical and physiological functions of the thoracic organs and help prevent other complications.

Adult↗
PubMed1997

[Cloning and expression of heavy- and light-chain variable region genes of monoclonal antibody specific for human fibrin].

OBJECTIVE: To obtain the minimum molecule having activity to bind human fibrin. METHODS: The immunoglobulin heavy- and light-chain variable region (VH and Vkappa) genes were isolated from 8E5 hybridoma cells, which secreted a monoclonal antibody against human fibrin, by RT-PCR. An expression vector pOPE51-8E5 was constructed for the recombinant VH-Vkappa expression. The transformed E. coli JM 109 cells were propagated and induced by IPTG. RESULTS AND CONCLUSION: Expression product was found in the periplasmic space and inclusion bodies by SDS-PAGE and immunobloting. It was a 30000 single chain fragment (scFv) with antigen-binding specificity. The yield of the scFv was 28.9% of the total bacterial proteins.

Animals↗
PubMed1997

Aircraft type and diagnosed back disorders in U.S. Navy pilots and aircrew.

BACKGROUND: Back disorders have long been recognized as a serious problem within the military aviation community and a possible threat to mission accomplishment. The purpose of the present study was to determine the extent to which the type of aircraft flown is associated with diagnosed back problems, and to examine differences in the prevalence of back disorders between pilots and aircrew. METHODS: A case-control study was conducted in which U.S. Navy pilots and aircrew members with a diagnosed back disorder on their most recent physical exam between 1991 and 1993 were compared with pilots and aircrew without such diagnoses. Data were obtained from the automated physical examination records maintained by the Naval Operational Medicine Institute for all Naval aviation personnel. RESULTS: Results showed that aircrew members have a higher risk of diagnosed back problems than pilots for both helicopters and fixed-wing aircraft. The study revealed that flight engineers have a higher risk of diagnosed back problems than other aircrew members. Among pilots, no association was found between type of aircraft and diagnosed back problems.

Adult↗