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Biomedical subjects

Q Ye

Publications and source records attributed to Q Ye.

At least 73 records · Page 4Linked to original sources
PubMed2000

[Proportional assist ventilation: methodology therapeutics on COPD patients compared with pressure support ventilation].

OBJECTIVE: To establish the method for clinical use of proportional assist ventilation (PAV) and evaluate the effect on COPD patients. The main similarities and differences of PAV and pressure support ventilation (PSV) were described. METHODS: 10 ventilated patients of COPD were studied. The elastance and resistance were determined before PAV by both inspiratory-hold technique during a brief period of volume control ventilation and "runaway technique". Either different assist levels of PAV (% assist 80%, 60%, 40%, respectively) or PSV was selected randomly. Values of hemodynamics, blood gas and pulmonary mechanics were monitored. Patients' response was described also. RESULTS: Runaway technique was convenient and reliable. Among different assist percentage no significant difference was found on hemodynamics in stabilized COPD patients. PaO2 was in a good level. Either tidal volume or respiratory rate did not change in a consistent way as the level of assist was decreased. But peak inspiratory pressure was increasing significantly r = 0.928 (P < 0.01) and patients' work of breath had the tendency to decrease (P < 0.05). A significant difference of Borg Category Scale was observed between PAV and PSV [0.50(1.50)] vs [0.75(2.00)], (P < 0.05). No significant difference of hemodynamics was found between the two modes. PaCO2 was significantly higher on PAV than on PSV, 54(24) and 48(23) mm Hg, respectively (P < 0.05). Peak inspiratory pressure on PAV (16 +/- 4) cm H2O was significantly lower than on PSV (21 +/- 3) cm H2O (P < 0.05). CONCLUSIONS: PAV is a feasible method of supporting ventilator-dependent patients that is well tolerated. It can improve breathing pattern and reduce inspiratory effort by decreasing work of breath. PAV can be implemented at much lower peak inspiratory pressure than PSV at the same condition of work of breath by patients. It can also apply proportional pressure support according to patients' ventilatory demand. System that operates according to the theory of PAV is not easy to implement. How to measure elastance and resistance is still a question during the development of PAV.

Aged↗
PubMed2000

[A clinicopathological study of hepatic focal nodular hyperplasia].

OBJECTIVE: To study the clinicopathological features of focal nodular hyperplasia (FNH). METHODS: The clinicopathological characteristics of 25 cases of FNH were studied retrospectively. 20 cases followed for 6 to 47 months. All were evaluated by use of paraffin-embedded sections, special and immunohistochemical staining (EnVision method) and electron microscope. RESULTS: 17 female and 8 male FNH patients aged 14 to 58 (median 38) years of age, all alpha-fetoprotein negative, asymptomatic and normal biochemical liver tests in most cases. The macroscopic hallmark is a central stellate fibrotic scar, composed of fibrous connective tissue and tortuous blood vessels, the fibrous tissue radiated peripherally, dividing the mass into multiple, variably sized nodules, simulating the pattern of cirrhosis. Microscopically, multinodular proliferation of benign-appearing hepatocytes separated by bile-duct-containing fibrous septae that radiate from the central scar. Internodular bile duct proliferation is abundant and merge imperceptibly with the hepatocyte elements near the fibrous septa. Immunohistochemically, the keratin expessed by hepatocytes and by the proliferated bile ducts were similar. Electron microscopic examination found that the ultrastructure of tumor cells were similar to normal hepatocytes. 20 cases were followed for 6-47 months, all survived with no recurrence. CONCLUSION: FNH is a benign hepatocytic lesion, i.e. a reactive proliferation of hepatic cells to local blood vessel anomalies.

Adolescent↗
PubMed2000

[ATP synthesis by free yeast catalysis coupling hollow fiber ultrafiltration separation].

A novel process for the ATP production employing free yeast catalysis and coupling a hollow fiber module ultrafiltration separation was studied. The experimental results of biocatalyst half-life and operating stability for ultrafiltration showed that the enzymes released from free yeast cell could be cut-off efficiently from the product output stream by hollow fiber membrane. The intercepted percentage of ADH and HK reached more than 95% during the steady running. The efficiency of enzymes utilized was 2.0-2.5 fold as much as that of batch reaction. And the time of yeast cells used repeatedly for ATP synthesis reached 2.5-3.0 batches. Under 0.1 MPa, the ultrafiltrating speed of hollow fiber membrane could keep on a stabilizing value for 11 batches continuously. The continuous operation mode of ATP synthesis simultaneous product ultrafiltration separation could be maintained in higher conversion rate for 5.0 h when the whole system fell in a pseudo-stat where the dilution rate was equal to 0.25 h-1.

Adenosine Triphosphate↗
PubMed2000

[Pharyngeal plexus neurectomy for voice restoration of alaryngeal].

OBJECTIVE: To release the spasm of pharyngeal constrictor and raise the successful rate of voice rehabilitation in total laryngectomized patients wearing Blom-Singer prosthesis. METHODS: The main branch of the pharyngeal plexus nerves within the inferior contractor can be found at the posterior side of hyoid greater cornu, which is about 6.5 mm from the back of constrictor. The spasm of the inferior constrictor can be resolved by cut off the nerve. RESULTS: Voice restoration was achieved in 15 cases after pharyngeal plexus neurectomy, the successful rate was 93.75%. CONCLUSION: It is feasible to replace pharyngeal myotomy by nerve plexus neurectomy and raise the voice rehabilitation rate.

Aged↗
PubMed2000

[Effects on the adjacent segment after spinal fusion and instrumentation].

This paper reviewed the literatures about the pathology at the segments adjacent to the fusion segments. The hypertrophic degenerative arthritis of the facet joints and spinal stenosis were the most common pathologic conditions. The pathology usually occurred at the upper segment in the patients of spinal fusion; and the lower segment would also show degeneration in those of instrumentation. The reason lied mainly in the increased stress at the adjacent segment after surgery and the change of segmental motion pattern. Symptoms usually developed within the first 5 years after fusion. Diagnosis depends on the clinical manifest and X-ray examination. Surgical intervention should be indicated if the conservative therapy failed, and decompression and fusion were most commonly applied.

Humans↗
PubMed2000

[Follow-up study of total condylar knee arthroplasty with three types of Chinese knee prosthetics].

OBJECTIVE: To clinical evaluate the results of total condylar knee arthroplasty using three types of Chinese knee prosthesis. METHODS: Hundred and two knees (in 92 patients) arthroplasty were performed in our department during the 14 years (April 1981-November 1995) were analyzed. The follow-up period averaged 64.4 months. Eight cases had died and 14 cases were lost of follow-up, leaving 80 knees in 70 patients for clinical evaluation. The clinical results were evaluated according to Hospital for Special Surgery Rating System. RESULTS: The average preoperative score was 47.65 and the postoperative score was 90.23. Almost all patients achieved significant pain relief after operation. Sixty-one of the 70 patients (87%) reported that they satisfied or very satisfied with the results of surgery. There were 6 failures. One was due to deep infection, one with loose patellar component, and four directly related to either improper selection or technical reasons. CONCLUSIONS: Total condylar knee arthroplasty with Chinese knee prosthetics gives a satisfactory grade of pain relief and movement of the operated knee. Chinese knee prosthetics is safety and durable.

Adult↗
PubMed1999

Recent experience with the arterial switch operation in transposition of the great arteries.

OBJECTIVE: Review of our experience with the technically demanding arterial switch operation in transposition of the great arteries in children. METHODS: Twenty-seven children who underwent an arterial switch operation in our clinic were retrospectively reviewed. Except for one child (operated on at eight months), the operation was performed during the neonatal period. The underlying pathology was d-transposition of the great arteries in 25 children and a double outlet right ventricle of transposition type in 2. Five children had an associated ventricular septum defect and 1 aortic isthmus coarctation. The pattern of the coronary arteries was favourable in 18 children, difficult in 7 and dangerous in 3. The operation was performed in cardiopulmonary bypass for repair of the transposition and in a period of deep hypothermic circulatory arrest for repair of the intracardiac defects. RESULTS: One child died perioperatively and 1 postoperatively (operative mortality 7%) from myocardial ischaemia following unsuccessful transfer of a dangerous pattern of coronary arteries. Another child, a low-birth weight baby, died 80 days after the operation from respiratory failure. Postoperative morbidity occurred in 10 patients and medium-term morbidity in 6 patients who presented various degrees of stenosis of a pulmonary artery. During a median follow-up of 18 months no patient required reoperation. The children are asymptomatic and thriving satisfactorily. CONCLUSION: Because it restores the heart physiology, the arterial switch operation is considered the procedure of choice for correction of transposition of the great arteries. The operation involves acceptable mortality and morbidity. Transfer of difficult coronary artery patterns and development of stenosis on the pulmonary arteries remain problematic.

Cardiopulmonary Bypass↗
PubMed1999

Operative results of "repair" of ventricular septal rupture after acute myocardial infraction.

Fifty-four consecutive patients with postinfarction ventricular septal defect were reviewed. The rupture was closed with a patch and the left ventricle remodeled in all patients. Coronary artery bypass surgery was performed in 28 patients (52%). Fourteen patients (26%) died after operation and 19 during follow-up (mean 42 months). Cumulative survival (including operative deaths) was 78%, 65%, and 40% at 1, 5, and 10 years, respectively. A short interval between septal rupture and operation was a risk factor for early mortality (p = 0.03). Treated associated coronary artery disease had no effect. A residual septal shunt, detected in 10 patients (18%), warranted reoperation in 7 and contributed to 2 early and 1 late death. The location and morphology of the septal rupture were not associated with increased risk of residual shunt. Thus, patch closure of the ventricular septal rupture, remodeling of the left ventricle to improve stroke volume and reduce wall stress, and selective myocardial revascularization provided acceptable results.

Aged↗
PubMed1999

Thickness of fibrous capsule after implantation of hydroxyapatite in subcutaneous tissue in rats.

The present study evaluates in rats the histomorphometrical thickness of fibrous capsules that surround hydroxyapatite (HA) disks after implantation. HA disks were implanted into the subcutaneous tissue of 79 rats for 1 day to 20 months. Decalcified histological sections stained with hematoxylin and eosin were examined. Fibrous capsule thickness (FCT) was measured using an objective micrometer. On the fourteenth day, primary fibrous capsules formed around implants. From that time point FCT increased with time of implantation. Within a given sample, FCT differed from one portion of the fibrous capsule to another, depending on which site faced the disks. FCT was thickest at the upper and lower portions of the disks, thinner at the lateral portions, and thinnest at the upper and lower ring-shaped portions. Two possible explanations for the above findings are discussed in this paper: (1) The area of contact between disk and tissue differs. (2) Chemical stimulation of implanted material caused by demineralization and remineralization may result from the varying thicknesses of fibrous capsules. FCT from upper and lower portions of HA disks increased by over 200% in the first 10 months and steadily increased about 20% over the next 10 months. Many studies have concluded that HA is useful for reconstructive surgery, so the long-term effects of FCT need further study.

Animals↗
PubMed1999

Crystallization and preliminary X-ray crystallographic analysis of spruce budworm antifreeze protein.

Antifreeze proteins have the ability to bind to ice with high affinity and inhibit further crystal growth. The insect antifreeze protein from spruce budworm exhibits very high thermal hysteresis activity and is implicated in the protection of overwintering larvae from freezing. This protein has been crystallized in 20-25% polyethylene glycol (Mr 6000), 0.4 M NaCl, 0.1 M Tris-HCl, pH 8.5, by vapor diffusion using the hanging drop method. The resulting crystals are very thin (typically <0.01 mm in the shortest dimension), and only after repeated seeding could crystals be grown large enough for data collection using synchrotron radiation. The crystals belong to the monoclinic space group C2, with cell dimensions a = 82.28 A, b = 62.29 A, c = 63.63 A, and beta = 113.7 degrees. Molecules in the asymmetric unit are related by a twofold axis of symmetry with two molecules present. Native data to a resolution of 2.6 A have been collected with 90.3% completeness and a Rsym of 6.9%.

Animals↗
PubMed1999

Donor hematopoietic progenitor cells in nonmyeloablated rat recipients of allogeneic bone marrow and liver grafts.

BACKGROUND: Although the persistence of multilineage microchimerism in recipients of long-surviving organ transplants implies engraftment of migratory pluripotent donor stem cells, the ultimate localization in the recipient of these cells has not been determined in any species. METHODS: Progenitor cells were demonstrated in the bone marrow and nonparenchymal liver cells of naive rats and in Brown Norway (BN) recipients of Lewis (LEW) allografts by semiquantitative colony-forming unit in culture (CFU-C) assays. The LEW allografts of bone marrow cells (BMC) (2.5x10(8)), orthotopic livers, or heterotopic hearts (abdominal site) were transplanted under a 2-week course of daily tacrolimus, with additional single doses on days 20 and 27. Donor CFU-C colonies were distinguished from recipient colonies in the allografts and recipient bone marrow with a donor-specific MHC class II monoclonal antibody. The proportions of donor and recipient colonies were estimated from a standard curve created by LEW and BN bone marrow mixtures of known concentrations. RESULTS: After the BMC infusions, 5-10% of the CFU-C in the bone marrow of BN recipients were of the LEW phenotype at 14, 30, and 60 days after transplantation. At 100 days, however, donor CFU-C could no longer be found at this site. The pattern of LEW CFU-C in the bone marrow of BN liver recipients up to 60 days was similar to that in recipients of 2.5x10(8) BMC, although the donor colonies were only 1/20 to 1/200 as numerous. This was expected, because the progenitor cells in the passenger leukocytes of a single liver are equivalent to those in 1-5x10(6) BMC. Using a liquid CFU-C assay, donor progenitor cells were demonstrated among the nonparenchymal cells of liver allografts up to 100 days. In contrast, after heart transplantation, donor CFU-C could not be identified in the recipient bone marrow, even at 14 days. CONCLUSION: effective immunosuppression, allogeneic hematopoietic progenitors compete effectively with host cells for initial engraftment in the bone marrow of noncytoablated recipients, but disappear from this location between 60 and 100 days after transplantation, coincident with the shift of donor leukocyte chimerism from the lymphoid to the nonlymphoid compartment that we previously have observed in this model. It is possible that the syngeneic parenchymal environment of the liver allografts constitutes a privileged site for persistent progenitor donor cells.

Adoptive Transfer↗
PubMed1999

Evidence for heat shock protein immunity in a rat cardiac allograft model of chronic rejection.

BACKGROUND: The stress response to injury concept has been proposed as a mechanism of chronic rejection. This hypothesis has been tested with a rat cardiac allograft model in recipients pretreated with donor bone marrow (BM) cells. Chronic rejection is manifested in this BM group by obliterative arteriopathy and the epicardium and endocardium contains lymphocytic infiltrates resembling Quilty lesions. Pretreatment with a liver allograft (the orthotopic liver transplant [OLTx] group) is associated with an absence of chronic rejection in the transplanted heart. METHODS AND RESULTS: . Stress responses in the allograft were assessed by determining heat shock protein (hsp) expression by immunohistology of graft tissues and immunoblot analysis of stromal tissue lysates with monoclonal antibodies (mAb) to mammalian hsp60, the inducible hsp72, the constitutively expressed hsc73, and the grp78 C-terminal sequence KSEKDEL (grp78seq). Immunostaining showed clusters of grp78seq-positive cells in the inflammatory infiltrates of obliterated blood vessels and Quilty lesions in the BM group of cardiac allografts. Such grp78seq-positive cells were not seen in the OLTx group of heart allografts nor in syngrafts. Neither group showed significantly different graft myocyte staining of grp78 or hsp72, whereas hsp60 and hsc73 showed higher expression in the BM group and, to a lesser extent, the OLTx group. The increased expression of hsc73 was seen especially in the obliterated arteries and in myocytes nearby cellular infiltrates. Immunoblot analysis of graft stromal tissue lysates showed additional bands with mAb to hsp60 and hsc73 for the OLTx and especially the BM group. No significant bands were seen for hsp72 and grp78. Lymphocytes isolated from chronically rejecting allografts reacted with irradiated autologous spleen cells in the presence of mycobacterial hsp65 and interleukin-2. Culturing of graft-infiltrating cells with mycobacterial hsp71 and interleukin-2 yielded lymphocyte clones without alloreactivity, but with strong proliferative responsiveness to self-antigen-presenting cells and, only in the presence of mycobacterial hsp71 or murine grp78. This T-cell reactivity seemed to require intact hsp molecules because treatment of hsp71 with proteolytic enzymes, polymyxin, or ATP abrogated this induction of the stimulatory effect of self-antigen-presenting cells. These T cells are similar to the hsp-dependent, autoreactive lymphocytes cloned from acutely rejecting rat allografts. CONCLUSIONS: These findings support the concept that the pathogenesis of chronic rejection involves a stress response and the participation of graft-infiltrating autoreactive T cells that operate under hsp-dependent mechanisms.

Animals↗
PubMed1999

Dendritic cells/chimerism/alleviation of chronic allograft rejection.

Chronic rejection (CR) is the major obstacle of long-term successful organ transplantation. Using a recently developed rat model of CR, we found that heart allografts susceptible to development of CR showed an early (< 10 days) dramatic disappearance of donor MHC class II+ cells, including ED2+ tissue macrophages, and an influx of recipient ED1+ macrophages intermixed with small numbers of recipient ED2+ and OX62+ cells. In contrast, donor MHC class II+ cells persisted in allografts resistant to CR with a small influx of recipient macrophages. MHC class II+ cells function as potent modulators of the immune system and may mediate both stimulatory and tolerogenic immune reactions after transplantation. Persistence of donor MHC class II+ antigen-presenting cells (APC) in CR-free graft acceptance suggests that transplantation tolerance is an active immune response requiring antigen presentation to the recipient immune system in the proper context by dendritic cells and other APC.

Animals↗
PubMed1999

Surgical repair of postinfarction structural failure of the posterobasal part of the heart.

BACKGROUND: This study is an analysis of our results with endoventricular repair of postinfarction structural defects of the posterobasal part of the heart. METHODS: Thirty-four patients who underwent endoventricular repair of a postinfarction structural defect of the posterobasal heart were reviewed. Patients with rupture of the ventricular septum (18 patients) or free wall (1 patient) were operated on acutely and patients with ventricular aneurysm (15 patients) electively. Restitution of the ventricular geometry was achieved by evertion (11 patients), resection (4 patients), or augmentation of the ventriculotomy (4 patients) in patients with ventricular rupture, and by resection of the aneurysm in the others. Coronary artery bypass was performed in 24 patients. RESULTS: Six patients died postoperatively (five due to rupture and one from aneurysm) and nine patients (six due to rupture and three from aneurysm) during follow-up. Survival rate at 5 years (including operative mortality) was 43% for patients with rupture and 61% for patients with aneurysm. The majority of the survivors were in New York Heart Association functional class I or II after a median follow-up of 5 years. CONCLUSIONS: Endocardial repair, ventricular remodeling, and selective myocardial revascularization provided overall good results in the treatment of this difficult cardiac area.

Aged↗
PubMed1999

Tissue engineering in cardiovascular surgery: MTT, a rapid and reliable quantitative method to assess the optimal human cell seeding on polymeric meshes.

OBJECTIVE: Currently used valve substitutes for valve replacement have certain disadvantages that limit their long-term benefits such as poor durability, risks of infection, thromboembolism or rejection. A tissue engineered autologous valve composed of living tissue is expected to overcome these shortcomings with natural existing biological mechanisms for growth, repair, remodeling and development. The aim of the study was to improve cell seeding methods for developing tissue-engineered valve tissue. METHODS: Human aortic myofibroblasts were seeded on polyglycolic acid (PGA) meshes. Cell attachment and growth of myofibroblasts on the PGA scaffolds with different seeding intervals were compared to determine an optimal seeding interval. In addition, scanning electron microscopy study of the seeded meshes was also performed to document tissue development. RESULTS: There was a direct correlation between cell numbers assessed by direct counting and MTT(3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltertra-zoliu m bromide) assay. Both attach rate and cell growth seeded on meshes with long intervals (24 and 36 h) were significantly higher than those seeded with short intervals (2 and 12 h) (P<0.01), there was no significant difference between 24- and 36-h seeding interval. Scanning electron microscopy also documented more cell attachment with long seeding intervals resulting in a more solid tissue like structure. CONCLUSION: It is feasible to use human aortic myofibroblasts to develop a new functional tissue in vitro. Twenty-four hours is an optimal seeding interval for seeding human aortic myofibroblasts on PGA scaffolds and MTT test is a rapid and reliable quantitative method to assess the optimal human cell seeding on polymeric meshes.

Biomedical Engineering↗
PubMed1999

Subunit mutations affect ethanol actions on GABA(A) receptors expressed in Xenopus oocytes.

1. Mutations of specific amino acids were introduced in transmembrane domains (TM) of GABA(A) receptor alpha2, beta1 and gamma2L subunits. The effects of these mutations on the action of ethanol were studied using the Xenopus oocyte expression system and two-electrode voltage-clamp recording techniques. 2. Mutant alpha2 subunits containing S270I (TM2) or A291W (TM3) made the receptor more sensitive to GABA, as compared to wild-type alpha2beta1gamma2L receptor. The mutation S265I (TM2) of beta1 and S280I (TM2) or S30IW (TM3) in gamma2L subunits did not alter apparent affinity of the receptor for GABA. M286W (TM3) in the beta1 subunit resulted in a receptor that was tonically open. 3. Using an EC5 concentration of GABA, the function of the wild-type receptor with alpha2beta1gamma2L subunits was potentiated by ethanol (50-200 mM). The mutations in TM2 or TM3 of the alpha2 subunit diminished the potentiation by ethanol. The action of ethanol was also eliminated with a mutation in the TM2 site of the beta1 subunit. Ethanol produced significant inhibition of GABA responses in receptors containing the combination of alpha2 and beta1 TM2 mutants with a wild-type gamma2L subunit. A small but significant reduction in the potentiation by ethanol was observed with gamma2L TM2 and/or TM3 mutants. 4. From these results, we suggest that in heteromeric GABA(A) receptors composed of the alpha, beta and gamma subunits, ethanol may bind in a cavity formed by TM2 and TM3, and that binding to the alpha or beta subunit may be more critical than the gamma subunit.

Amino Acid Sequence↗
PubMed1999

Subcutaneous inflammatory reaction to a synthetic auditory ossicle (Bioceram) in rats.

Cellular response and inflammatory reaction to synthetic auditory ossicle (Bioceram) made from aluminium oxide are investigated. Local inflammatory effects are important in wound healing and in determining biocompatibility of an implant, necessitating the study of biologic effects of implants, especially inflammation and fibrous capsule formation. Bioceram discs were implanted subcutaneously in the interscapular region of rats for various periods of time, ranging from 1 day to 300 days. Histological sections 6 microns thick were stained with haematoxylin and eosin. Cell types around the implants were examined quantitatively by light microscopy. Inflammatory cell reaction to Bioceram decreased rapidly within 14 days, similar to the reaction in control groups. From 30 days to 300 days after implantation, there was continuous reduction to very low levels for macrophages and lymphocytes, but fibrous connective tissue capsule around implants matured. Preliminary results suggest that Bioceram is a satisfactory biocompatible material for reconstructive surgery from the viewpoint of cellular response. We also briefly discuss the different tissue responses in light of our previous study on hydroxyapatite (Apaceram).

Aluminum Oxide↗