Biomedical subjects

D Han

Publications and source records attributed to D Han.

At least 55 records · Page 3Linked to original sources

PubMed2001

[Hydroxyapatite for experimental laryngotracheal reconstruction].

OBJECTIVE: The porous hydroxyapatite (HA) tubiform prosthesis was employed for reconstruction of large circumferential defect of the larynx and cervical trachea. The biocompatibility, bioactivity and biofunctionality of the HA prosthesis were evaluated, and the feasibility for laryngotracheal reconstruction was discussed. METHODS: Twelve healthy canines were used to establish the experimental models, a large portion of cricoid cartilage and upper ten-ring segment of cervical trachea were resected and substituted with a corresponding 5 cm HA prosthesis by end-to-end anastomosis. Six months later, the eight survival canines were sacrificed and the HA prostheses with surrounding tissues were removed. They were observed in decalcified sections by optical microscopy and scanning electron microscopy. RESULTS: Two canines died in the immediate postoperative period with unknown reason and another two deaths were attributed to obstruction caused by the complete dislocation of the HA prostheses owing to rupture of the sutures within three weeks after operation. Eight canines survived up to six months. The implanted HA prostheses were tolerated in all cases without any rejection and dislocation or shift. An excellent airway was obtained and no signs of dyspnea and suffocation were found though there were hypergranulation and scar formation occurred at the site of anastomosis. Morphologic examination revealed that collagen fibers, new vessels and plenty of cells penetrated deeply into the pores of HA, and occupying the outer two third of HA wall. HA prostheses were surrounded by connective tissues and anchored firmly to the neighboring tissues, including the ends of the cricoid and tracheal cartilage by ingrowths of cartilaginous tissue into the macropores of the HA. However, the luminal surface of HA prosthesis was not covered at all section levels by respiratory mucosa. CONCLUSIONS: The implantation of the porous HA tubiform prosthesis can maintain the normal respiratory function of the experimental canines, but the proliferating granulation and scar formation at the anastomotic site are questions still remained to be solved. To cover the inner surface of HA with the epithelial mucosa and then reduce the morbidity caused by scar and hypergranulation, some forms of allografts such as pedicled flaps and jejunal autografts will be deserved.

Animals↗

PubMed2001

[Determining the site of airway obstruction in obstructive sleep apnea with airway pressure measurements during sleep].

OBJECTIVE: Determine the site(s) of upper airway obstruction and the influence of sleep stage on the pattern of obstruction with upper airway (UA) pressure measurement. Analyses the clinical value of UA pressure measurement and it's influenced factors. METHODS: 30 OSAS patients underwent UA pressure measurement during polysomnography. Multisensory pressure catheters with five solid-state ultraminiature sensors were insert through patients' upper airway to esophagus, The sensors were located at the nasopharynx, oropharynx, tongue base, hypopharynx and esophagus and the lower limit of UA obstruction was determined relying on the observed pressure pattern. RESULTS: (1) During inspiration, obstruction occurred associated with a increased negative inspiratory pressure inferior to the site of obstruction and a disappeared negative inspiratory pressure above the site of obstruction. (2) Three patterns of obstruction were observed. 1. The site of obstruction was located at the level of the palate. 2. The level of the palate and tonguebase obstruction all present. 3. Nasopharyngeal obstruction soft plate obstruction and tongue-pharynx obstruction all present. (3) The factors which affected these measurement are 1. The catheter were placed by observation with a fiberoptic endoscope to keep the sensors located at the correct position. 2. Catheter plugging with secretions need to be prevented. CONCLUSION: UA pressure measurement can objectively identify the level of obstruction during sleep.

Adult↗

PubMed2001

[Evaluation of clinical application of intravascular ultrasound image].

OBJECTIVE: To prospectively evaluate the clinical applications of intravascular ultrasound (IVUS). METHODS: Four hundred and thirty seven patients with coronary artery disease (CAD) or suspect CAD were imaged with CAD and IVUS, including (1) assessment IVUS in 135 cases with normal coronary angiography (CAG) (2) comparison IVUS with CAG pre and after angioplasty in 52 patients with CAD (3) assessment of detecting calcification lesions with CAG and IVUS in 150 patients (4) predicting the cardiac events after stent implantation guided by IVUS (n = 47) and CAG (N = 53). RESULTS: IVUS may detect coronary atherosclerosis lesions with normal by CAG. CAG overestimated effect of angioplasty. IVUS was more accurate to determine effect and complications of PTCA compared with CAG. IVUS interpreted the mechanism of vessel dilatation in PTCA. The cardiac events after stent implantation were significantly reduced after IVUS examination as compared with CAG. CONCLUSIONS: IVUS represents a radically different approach to vascular anatomy. Unlike angiography, which displays the coronary artery as a silhouette of the contrast-filled lumen, IVUS generates a cross-sectional tomographic image of the lumen and vessel wall. IVUS plays an important role as a guidance in cardiac intervention.

Adult↗

PubMed2000

Quantitative polymerase chain reaction assessment of chimerism in non-human primates after sex-mismatched islet and bone marrow transplantation.

BACKGROUND: Accurate assessment of chimerism in recipients of islet and bone marrow transplantation (BMT) may allow for a clearer assessment of the role of chimerism in islet engraftment or rejection. A quantitative polymerase chain reaction (PCR) assay was developed for the detection of the sex-determining region of the Y chromosome (SRY) in peripheral blood samples from female non-human primate recipients of allogeneic male islets and vertebral body marrow (VBM) from the same donor. METHODS: The assay incorporates a synthetic internal standard (IS) containing the same primer template sequences as the target to compete for primer annealing and amplification. Each DNA sample was coamplified with a constant amount of IS. The concentration of male DNA in the test samples was calculated from the regression equation of a standard curve that was generated by plotting the logarithm of the ratio of the intensities of SRY to IS PCR products versus the logarithm of known percentages of input male DNA. RESULTS: This method allows for a correction of the variability of efficiency of the PCR technique and also overcomes the drawback of time-consuming competitive PCR. Using this assay, we quantitated the amount of male DNA in samples taken from female baboon recipients of male islets and VBM. There was detectable male donor DNA in the samples taken one day after BMT; pre-BMT samples were negative. This technique works well for samples obtained from rhesus and cynomogus monkeys as well. CONCLUSIONS: It is a practical method for accurately evaluation of chimerism after sex-mismatched allogeneic BMT in non-human primate models.

Animals↗

PubMed2000

Comprehensive analyses of prostate gene expression: convergence of expressed sequence tag databases, transcript profiling and proteomics.

Several methods have been developed for the comprehensive analysis of gene expression in complex biological systems. Generally these procedures assess either a portion of the cellular transcriptome or a portion of the cellular proteome. Each approach has distinct conceptual and methodological advantages and disadvantages. We have investigated the application of both methods to characterize the gene expression pathway mediated by androgens and the androgen receptor in prostate cancer cells. This pathway is of critical importance for the development and progression of prostate cancer. Of clinical importance, modulation of androgens remains the mainstay of treatment for patients with advanced disease. To facilitate global gene expression studies we have first sought to define the prostate transcriptome by assembling and annotating prostate-derived expressed sequence tags (ESTs). A total of 55000 prostate ESTs were assembled into a set of 15953 clusters putatively representing 15953 distinct transcripts. These clusters were used to construct cDNA microarrays suitable for examining the androgen-response pathway at the level of transcription. The expression of 20 genes was found to be induced by androgens. This cohort included known androgen-regulated genes such as prostate-specific antigen (PSA) and several novel complementary DNAs (cDNAs). Protein expression profiles of androgen-stimulated prostate cancer cells were generated by two-dimensional electrophoresis (2-DE). Mass spectrometric analysis of androgen-regulated proteins in these cells identified the metastasis-suppressor gene NDKA/nm23, a finding that may explain a marked reduction in metastatic potential when these cells express a functional androgen receptor pathway.

DNA, Complementary↗

PubMed2000

Involvement of nitric oxide in pentylenetetrazole-induced kindling in rats.

We investigated the role of nitric oxide (NO) and brain-derived neurotrophic factor (BDNF) in the pentylenetetrazole (PTZ)-induced kindling in rats. Seizures were induced by single administration of PTZ, which was associated with an increase in levels of NO metabolites (NOx) in the hippocampus. Pretreatment with a neuronal NO synthase inhibitor, 7-nitroindazole (7-NI), diminished the PTZ-induced increase in NOx levels without affecting the seizure intensity. Repeated administration of PTZ produced a gradual increase in the seizure intensity, leading to the development of kindling. In the kindled rats, PTZ at a dose of 40 mg/kg increased NOx levels in the hippocampus, whereas it had no effect in control animals. Cotreatment of 7-NI with PTZ blocked the development of kindling and attenuated the PTZ-induced increase in NOx levels. A significant increase in BDNF levels was observed in the hippocampus of the kindled rats, which returned to the control levels following seizures induced by PTZ. 7-NI reduced the hippocampal BDNF levels in control rats and suppressed the increase of BDNF levels in the kindled rats. Our findings suggest that NO plays a role in the development of PTZ-induced kindling and that BDNF may contribute to the NO-dependent plastic changes in neuronal excitability.

Animals↗

PubMed2000

Antioxidants and herbal extracts protect HT-4 neuronal cells against glutamate-induced cytotoxicity.

Antioxidant therapy has been shown to be beneficial in neurological disorders including Alzheimer's disease and cerebral ischemia. Glutamate-induced cytotoxicity in HT-4 neuronal cells has been previously demonstrated to be due to oxidative stress caused by depletion of cellular glutathione (GSH). The present study demonstrates that a wide variety of antioxidants inhibit glutamate-induced cytotoxicity in HT-4 neuronal cells. Low concentrations of alpha-tocopherol and its analogs were highly effective in protecting neuronal cells against cytotoxicity. Purified flavonoids and herbal extracts of Gingko biloba (EGb 761) and French maritime pine bark (Pycnogenol) were also effective. We have previously shown that pro-glutathione agents can spare GSH and protect cells from glutamate insult in a C6 glial cell model. The protective effects of nonthiol-based antioxidants tested in the HT-4 line were not mediated via GSH level modulation. In contrast, protective effects of thiol-based pro-glutathione agents alpha-lipoic acid (LA) and N-acetyl cysteine (NAC) corresponded with a sparing effect on GSH levels in glutamate-treated HT-4 cells. Glutamate-induced cytotoxicity in HT-4 cells is a useful model system for testing compounds or mixtures for antioxidant activity.

Animals↗

PubMed2000

Interferometers and decoherence matrices

It is shown that the Lorentz group is the natural language for two-beam interferometers if there are no decoherence effects. This aspect of the interferometer can be translated into six-parameter representations of the Lorentz group, as in the case of polarization optics where there are two orthogonal components of one light beam. It is shown that there are groups of transformations which leave the coherency or density matrix invariant, and this symmetry property is formulated within the framework of Wigner's little groups. An additional mathematical apparatus is needed for the transition from a pure state to an impure state. Decoherence matrices are constructed for this process, and their properties are studied in detail. Experimental tests of this symmetry property are possible.

Journal Article↗

PubMed2000

Diffusion-convection equation solved in parallel regions of the lung.

The single path model of airway gas transport was incorporated into each of Cruz (Cruz, J. C. Respir. Physiol. 86:1-14, 1991). Thus, the effect of time on the predicted gas fractions in and out of the lung could be evaluated. Two experimental maneuvers were simulated: (1) fast inhalation of an argon-oxygen mixture from a functional residual capacity and fast exhalation to residual volume, including inspiratory breath holdings of 5-20 s, and (2) the standard single-breath nitrogen washout test. Expired argon and nitrogen are predicted within a +3% error of the experimental data with no breath holding. Breath holding predictions were at variance with experimental results because the solution of the diffusion-convection equation produced even mixing in the alveoli at the end of inspiration. The minimum square of the difference between the experimental data (standard single-breath nitrogen washout test) and those provided by the model was 0.0016. This model is capable of generating a nitrogen expirogram with four phases when a vital capacity of oxygen is inhaled. However, the model failed to produce a sharp distinction between phase 3 and phase 4. Thus, we conclude that uneven emptying of parallel regions generates any expirogram (a fast or slow expiratory maneuver). The alveolar gas stratification that is created during inspiration disappears at the end of the inspiratory maneuver. As a result, breath holding maneuvers cannot be predicted in the anatomical model used.

Biomedical Engineering↗

PubMed2000

Dominant-negative inhibition of prion formation diminished by deletion mutagenesis of the prion protein.

Polymorphic basic residues near the C terminus of the prion protein (PrP) in humans and sheep appear to protect against prion disease. In heterozygotes, inhibition of prion formation appears to be dominant negative and has been simulated in cultured cells persistently infected with scrapie prions. The results of nuclear magnetic resonance and mutagenesis studies indicate that specific substitutions at the C-terminal residues 167, 171, 214, and 218 of PrP(C) act as dominant-negative, inhibitors of PrP(Sc) formation (K. Kaneko et al., Proc. Natl. Acad. Sci. USA 94:10069-10074, 1997). Trafficking of substituted PrP(C) to caveaola-like domains or rafts by the glycolipid anchor was required for the dominant-negative phenotype; interestingly, amino acid replacements at multiple sites were less effective than single-residue substitutions. To elucidate which domains of PrP(C) are responsible for dominant-negative inhibition of PrP(Sc) formation, we analyzed whether N-terminally truncated PrP(Q218K) molecules exhibited dominant-negative effects in the conversion of full-length PrP(C) to PrP(Sc). We found that the C-terminal domain of PrP is not sufficient to impede the conversion of the full-length PrP(C) molecule and that N-terminally truncated molecules (with residues 23 to 88 and 23 to 120 deleted) have reduced dominant-negative activity. Whether the N-terminal region of PrP acts by stabilizing the C-terminal domain of the molecule or by modulating the binding of PrP(C) to an auxiliary molecule that participates in PrP(Sc) formation remains to be established.

Animals↗

PubMed2000

A case of primary intestinal T-cell lymphoma involving entire gastrointestinal tract: esophagus to rectum.

Primary intestinal T-cell lymphoma is a rare disease entity, which is approximately 10% to 25% of intestinal lymphomas, and most of the lymphomas occur in the small intestine. We report here a case of a 56-year-old woman who has been suffering from chronic diarrhea and weight loss for 6 months. Abdominal CT scan and small bowel series showed diffuse wall thickening of the small bowel. Gastroscopic examination showed diffuse erythematous lesions on the esophagus and small gastric ulcerations on the antrum of the stomach, and colonoscopic examination also showed multiple punched-out ulcerations and erosions on the entire colon, including the sigmoid colon to the terminal ileum. Diffuse infiltration of CD 3 positive lymphoma cells was found on biopsy. The patient was diagnosed as primary intestinal T-cell lymphoma with diffuse involvement of the entire gastrointestinal tracts from the esophagus to the rectum. Although the patient received systemic combination chemotherapy and achieved partial response initially, the lymphoma relapsed repeatedly.

Esophageal Neoplasms↗

PubMed2000

Effects of intestinal endotoxemia on pathogenesis of liver injury induced by thioacetamide.

OBJECTIVE: To study the effect of intestinal endotoxemia on pathogenesis of liver injury induced by thioacetamide (TAA). METHODS: Twenty-six male Wistar rats were divided into 4 groups, namely: normally control group (N), colectomy control group (C), colectomy+TAA group (C+T), TAA group (T). The changes in plasma biochemistry were measured. RESULTS: Plasma endotoxin levels were significantly higher in TAA group than normally control group. Plasma endotoxin levels in colectomy+TAA group were close to that of normally control group. Plasma ALT activity in colectomy+TAA group increased significantly compared with that of normal control group, but markedly lower than that in TAA group. Plasma endotoxin levels were positively correlated to ALT activity in T and C+T groups (r=0. 985, P<0.01). CONCLUSION: TAA itself has a deleterious effect to hepatic cells. It can also induce intestinal endotoxemia in which the liver injury is more inclined to occur and severe.

Alanine Transaminase↗

PubMed2000

[Studies on behavioral and electrographic seizures and structural abnormalities using magnetic resonance image in chronic epilepsy model in rats--hippocampal-entorhinal-tempral neocortex neural pathway].

AIM AND METHODS: Repeated tetanus (60 Hz, 0.4-0.6 mA, 2 s) were delivered into the right and the left dorsal hippocampus (HPC), or into the right and the left medial temporal neocortex (MTNC) respectively to establish chronic temporal lobe epilepsy model in rats. The possible role of the HPC-Entorhinal cortex (EC)-MTNC-Neocortex neural pathway in epileptogenesis was discussed based on observing the abnormalities in behavior and in EEG or depth electrographes and in T2-weighted magnetic resonance images (T2-MRI). RESULTS: 1. Occurrence of primary, secondary WEDS and kindling effects were higher in the right dorsal HPC experimental group than those in other three experimental groups (P < 0.005, P < 0.001). T2-MRI signal hyperintensity was remarkable in lateral ventricles close to the HPC (P < 0.05), but not in the EC or in the MTNC. 2. These T2-MRI intensity increases were related to behavioral abnormalities in some MTNC-stimulated rats. 3. Asymmetric behavioral abnormalities and T2-MRI changes were observed in the left and the right DHPC-stimulated groups. CONCLUSION: HPC may be an "origin" for epileptogenesis and EC may play a "gating" role in it.

Animals↗

PubMed2000

[Ecological planning and designing in agricultural landscapes].

Based on the theories of landscape ecology, this paper discussed the principles and methods of ecological planning and designing in agricultural landscapes. It is suggested that the ecological planning and designing in agricultural landscapes became an important applied field of landscape ecology, due to the characteristics of microspatiality, and correlation and integration involved problems. The Zhuolu basin, located in the semiarid region of northwest Hebei Province was chosen as a case study.

Agriculture↗

PubMed2000

[Effects of intranasal budesonide on the infiltration and activation of eosinophils in nasal polyps].

OBJECTIVE: To assess the effects of topical nasal steroid application on the infiltration and activation of eosinophils in nasal polyps. METHODS: Nasal polyps from intranasal budesonide treated patients (n = 16) and untreated patients (n = 16) were investigated. The samples were stained with histochemical and ABC immunohistochemical methods. RESULTS: The majority of eosinophils in nasal polyps were activated eosinophils. Compared with untreated polyps, the proportion of activated eosinophils (EG2+/eosinophil ratio) was significantly less in steroid-treated polyps. Although the numbers of total eosinophils and actived eosinophils were lower in steroid-treated polyps, both of the differences were not statistically significant. CONCLUSIONS: It emphasized that the actived eosinophils play a key role in the pathogenesis of nasal polyps. The effects of intranasal steroid treatment on the number of eosinophils (total and activated) was more profound then on the proportion of activated eosinophils.

Administration, Topical↗

PubMed2000

[Giant cell reparative granuloma of the skull].

OBJECTIVE: To investigate the clinical course, histologic feature, diagnosis, differential diagnosis and treatment of giant cell reparative granuloma (GCRG). METHODS: Three cases of GCRG, which arose in the skull, were collected from 1987 to 1999 and analyzed clinicopathologically. RESULTS: Two patients had the lesion in the temporal bone and one in the orbit. One patient with GCRG had a recurrence after incomplete surgical resection. Histologically, all of three cases were characterized by fibroblastic proliferation with osteoclast-like giant cell rich areas, hemorrage, and newly formed bone or osteoid trabeculae. GCRG appeared as a typical bony lytic lesion on computed tomography (CT) and as low signal intensity on both T1 and T2 weighted images on magnetic resonance imaging (MRI). CONCLUSION: GCRG is an uncommon nonneoplastic lesion that typically arises in mandible and maxilla and its involvement in skull is rare. Although behaves benignly, GCRG may be locally aggresive. It is usually misdiagnosed for a giant cell tumor (GCT). Diagnosis of GCRG is based on typical histologic features as well as clinical information. Complete surgical resection is believed to be the most suitable treatment for GCRG and long-term follow-up by CT scanning is essential.

Adult↗

PubMed2000

[The application of epiglottis in laryngeal function reconstruction after partial laryngectomy].

OBJECTIVE: To observe the appliance value of epiglottis in laryngeal function reconstruction after partial laryngectomy. METHODS: Thirty-two cases of glottic and superglottic carcinomas of larynx had conducted partial laryngectomy and the laryngeal function was reconstructed using epiglottis from December. 1992 to January 1996. RESULTS: Nineteen of the twenty-one glottic carcinomas and five of eleven supraglottic carcinomas were decannulated and recovered with laryngeal functions. All the patients rehabilitated deglutition in 14-18 days after surgery. None presented complication of aspiration. CONCLUSIONS: Epiglottis has many advantages in partial laryngectomy and the laryngeal reconstruction. It is easy to approach, apply and heal in short period. It also prevents aspiration and improves the decannulation rate as well as the quality of life in partial laryngectomy patients.

Adult↗

PubMed2000

[Sodium salicylate induced intracellular Ca2+ concentration change in guinea pig outer hair cells].

OBJECTIVE: In order to explore the mechanism of sodium salicylate ototoxicity the effect of sodium salicylate on intracellular Ca2+ ([Ca2+]i) of the outer hair cells (OHCs) and the effects of calcium channel antagonist on sodium salicylate-induced [Ca2+]i changes of the OHCs were examined. METHODS: The OHCs of guinea pig cochlear were isolated using an enzyme-machine methods and loaded with 10 mumol/L Fluo-3/AM for 30 min at 37 degrees C. Individual Fluo-3 loaded OHC was examined with a confocal microscope (ACAS Ultima, USA) using a 20 x objective lens and linear scan mean. The fluorescent images, collected each 5-sec for 300 sec, were stored in a computer. The fluorescent intensity of the OHCs were analyzed by the software cooperated with the confocal microscope, and a curve of fluorescent intensity changes trend against time was obtained. RESULTS: The [Ca2+]i of OHCs were steady under normal extracellular liquid perfusion. Salicylate increased [Ca2+]i in OHCs in calcium-free medium(10/10) and standard medium (8/10). 3 mmol/L lidocaine inhibited [Ca2+]i increase in OHCs induced by salicylate(0/10). The [Ca2+]i increase in OHCs induced by salicylate could be blocked by flunarizine(3/12). Nimodipin failed to block the [Ca2+]i increase of OHCs induced by salicylate (7/7). CONCLUSION: Sodium salicylate can result in [Ca2+]i increase in OHC markedly, which may be due to the Ca2+ release from intracellular calcium stores. The effects of salicylate on [Ca2+]i in OHCs might be one of the mechanisms of salicylate ototoxicity.

Animals↗