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L Cai

Publications and source records attributed to L Cai.

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

[Surface EMG signal classification using wavelet transform].

A Surface EMG signal classification method based on wavelet transform is presented in this paper. To utilize the nonstationary character of the EMG signals, dyadic wavelet transform is employed to obtain the signals' time-frequency representation. Singular value decomposition(SVD) is then used to extract feature vector for pattern classification. This motion classifier can successfully identify four types of forearm movement: hand grasp, hand extension, forearm pronation and forearm supination. Experimental result shows that this method has a great potential in the practical application of prothesis control.

Electromyography↗
PubMed2000

[Elevated substance P content in sputum and plasma in patients with COPD and its relationship with FEV1/FVC].

OBJECTIVE: To investigate the role of substance P(SP) of the nonadrenergic system within airways in the pathogenesis of COPD, and analyze the relationship between level of SP and FEV1/FVC in COPD patients. METHOD: SP concentration in sputum and plasma in 20 patients with COPD and 20 normal volunteers was examined and was measured by radioimmunoassay. RESULTS: The sputum SP concentration was significantly higher in patients with COPD (57.3 +/- 14.5) pmol/L than that in normal volunteers(5.9 +/- 2.6) pmol/L, P < 0.01, the plasma SP concentration was significantly higher in COPD patients (8.6 +/- 3.9) pmol/L than that in normal volunteers (3.8 +/- 2.0) pmol/L, P < 0.05. The plasma and sputum SP concentration correlated with FEV1/FVC in COPD patients (r = -0.591, r = -0.642, P < 0.05). CONCLUSION: These data suggest that neurogenic inflammation may be involved in the airway inflammation process and subsequent airway narrowing in COPD.

Aged↗
PubMed2000

Pancreatic insulinomas: experience in 220 patients.

OBJECTIVE: To summarize the experience in the diagnosis and treatment of insulinoma. METHODS: We retrospectively reviewed 220 patients with insulinoma confirmed surgically in the PUMC Hospital from 1953 to 1999. They were 131 men and 89 women, aged on average 39 years. RESULTS: In the 220 patients, the average interval from the onset of symptoms to diagnosis was 35 months. 54% of the patients were misdiagnosed before admission to the hospital. In 214 patients underwent operation, 201 (93.9%) had benign tumor and 12 (5.6%) malignant one. The diameter of 78% tumors was less than 2cm. 90.7% tumors were single and 9.3% were multiple. 37.1% tumors were located in the head and uncinate process of the pancreas, 26.1% in the body, 36.1% in the tail, and 0.7% ectopic. 95.5% patients had Whipple's triad and the ratio of insulin to glucose was greater than 0.3 in 89% patients. The positive rates of B-ultrasound, CT and MRI for localization before operation were low, but those of angiography and PTPC were 62.8% and 88% respectively. Most patients could be cured by simple enucleation of tumor. The main complications were pancreatic fistulae and pancreatitis. CONCLUSION: It is important for surgeons to familiarize with insulinoma, the most common islet cell tumor, for a better treatment.

Adult↗
PubMed2000

[Photodynamic therapy of hematoporphyrin derivative on human pancreatic carcinoma cell lines].

OBJECTIVE: To observe the effect of photodynamic therapy (PDT) on human pancreatic carcinoma cell lines in vitro. METHODS: Two lines of human pancreatic carcinoma cell P3 and SW1990 were studied to investigate the killing role of PDT with hematoporphyrin derivative (HPD) as photosensitizer and sodium lamp as light source. The cultured cells were treated with serial concentrations of HPD followed by irradiation of different dosages of visible light, then MTT colorimetric assay was applied to measure the relative inhibitory rate of PDT for the cells. RESULTS: The relative inhibitory rate of PDT for the cells elevated along with the increase in the concentration of sensitizer and dose of light. Under the low photodynamic dose, it increased rapidly, and gradually slowed down to reach the plateau. Under the same photodynamic dose, significant difference in the inhibitory rate between the two lines was observed (P < 0.01), and the LD90 was also different. CONCLUSIONS: PDT has a significant killing effect on human pancreatic carcinoma cell lines in vitro, and its relative inhibitory rate appears to be correlated with the dose of sensitizer and light irradiation. The sensitivity of the two cell lines to PDT is different.

Cell Line, Tumor↗
PubMed2000

[Simultaneous pallidotomy and thalamotomy for Parkinson's disease with intractable tremor].

OBJECTIVE: To evaluate the clinical necessity, outcomes, safety, and indications of contemporary combined pallidotomy and thalamotomy for Parkinson's disease (PD) with intractable tremor. METHODS: The UPDRS data from 20 patients who received simultaneous pallidotomy and thalamotomy were analyzed retrospectively. During the same period, 326 patients were subjected to unilateral pallidotomy. Improvement and complications between the two groups were compared. RESULTS: Contemporary pallidotomy and thalamotomy effectively improved parkinsonian symptoms as did pallidotomy alone. This procedure completely abolished intractable tremor in all 20 patients. No permanent complications occurred. CONCLUSIONS: Contemporary combination of pallidotomy and thalamotomy is effective and safe in treating regular parkinsonian symptoms and intractable tremor.

Adult↗
PubMed2000

[Morphological changes of cultured rabbit retinal cells after injury].

PURPOSE: To investigate the morphological changes of cultured rabbit retinal cells after injury. METHODS: Mechanical scratch was done in nenatol rabbit retinal cell culture and in Schwann Cell(SC)/retinal cell colculture. The morphological changes of different sorts of cells after the injury were observed under the phase contrast microscope for 24 h. RESULTS: About 30 min after injury, many glial cells moved to the blank region and proliferated to form gliosis. Axons of retinal neurons began to regenerate 6 h post injury. The direction of regrowth was influenced by the environment. In the coculture, regeneration of axons was discerned only 3 h after injury. CONCLUSION: Axons of retinal neurons had strong capability of regeneration; Gliosis was not the absolute obstacle of regeneration; SC played a role in promoting the axon regeneration.

Animals↗
PubMed2000

[Change of 5-fluorouracil penetration in blood-pancreatic barrier of rats after high-dose radiotherapy].

OBJECTIVE: The high-dose intraoperative radiotherapy has become an important therapy to control local recur of pancreatic carcinoma. But the relevant effect of high-dose radiotherapy on chemotherapy is not clear now. METHODS: We studied the effect of high-dose radiotherapy to the penetration of 5-FU (5-Fluorouracil) in blood-pancreatic barrier of rats after the pancreatic region of the rats had treated with 10(Gy) external beam radiotherapy, the penetration ratio (PR) of 5-FU in the pancreatic tissue was investigated with HPLC assay. RESULTS: We found the PR increased with the time processing. And reached the peak on the 6th day, (PR = 0.8300 +/- 0.1662, P < 0.05). Then, the PR began to descend and was 0.7028 on the 10th day. But it was still significantly higher than control group (P < 0.05). CONCLUSION: After the treatment of high-dose radiotherapy, in addition to chemotherapy on the 4th day, and finished the course on the 10th day, the effect of radiotherapy may improve chemotherapy significantly.

Animals↗
PubMed2000

[In situ FTIR spectrocopic studies of CO and CN- adsorbed on electrode of nanometer thin film of palladium in alkaline solutions].

The adsorption and coadsorption of CO and CN- on electrode of nanometer thin film of palladium (nm-Pd/GC) was studied by using in situ FTIR spectroscopy. The results demonstrated that the nm-Pd/GC electrode exhibited abnormal infrared effects (AIREs) in alkaline solutions as in acid solutions. The characters of AIREs, i.e., the inversion of the direction of IR band, the augmentation of FWHM and the significant enhancement of IR absorption by adsorbed species were observed in all cases of adsorption and coadsorption of CO and CN-. It has been illustrated that strong interaction is existed between adsorbed CO and CN- on nm-Pd/GC surface. The study has contributed towards understanding the surface processes of chemisorption as well as to reveal the origin of nanometer size-effects of thin film materials.

English Abstract↗
PubMed1999

Characteristics of hospitalizations of HIV-infected patients: an analysis of data from the 1994 healthcare cost and utilization project.

Hospitals are significant resources for care of HIV/AIDS patients. Previous studies that have attempted to identify and track the characteristics of these patients and their hospitalizations have been limited in their ability to produce national estimates of patient use of such resources. This study, using data from the Healthcare Cost and Utilization Project (HCUP-3) attempted to characterize and estimate the cost of hospital usage by HIV/AIDS patients. We estimate that in 1994 approximately 188,506 admissions of HIV/AIDS patients occurred with an average charge of $19,244 U.S. per admission, for an estimated total cost of $3.63 billion. Compared with non-HIV-infected patients, HIV/AIDS patients tended to be male (75.83% versus 41.49%), a member of a minority group (53.51% versus 20.77%), hospitalized in a private, nonprofit, urban teaching hospital with a longer average length of stay (10.27 versus 5.52 days), and to have a higher in-hospital mortality (11.45% versus 2.58%). Approximately half of the hospital charges (47%) for these admissions were absorbed by Medicaid, and 25% by private insurance. The remainder of the charges were borne by the patients themselves. The results presented here for 1994 predate the widespread use of protease inhibitor/ highly active antiretroviral therapy (HAART), thus making this study an important benchmark for the delineation of the effects of HAART and any other future developments in HIV therapy on the characteristics of HIV/AIDS patient resource use on a national level. This study further demonstrates that HCUP is a powerful tool for the estimation and costing of hospital resource use.

Adult↗
PubMed1999

Relatively low-dose cyclophosphamide is likely to induce apoptotic cell death in rat thymus through Fas/Fas ligand pathway.

Cyclophosphamide (CPA) is widely used as an efficiently antineoplastic drug, but also causes immunosuppression as its adverse-side effect. To understand the effect of low- or relative low-dose CPA on the immune system, apoptotic cell death in rat thymus, either exposed to different doses of CPA (0, 2, 7, 20 and 70 mg/kg) for 12 h or exposed to 70 mg/kg for different times (4-48 h), was investigated by DNA fragmentation (DNA ladder) detection and in situ morphological examination using hematoxylin and eosin (H and E) staining. Immunohistochemical staining for Fas protein expression in the thymus of rats exposed to CPA was performed. Results showed that exposure of rats to CPA 0-70 mg/kg for 12 h did not cause significant decrease in the ratio of thymus weight to body weight. However, the ratio of thymus weight to body weight was decreased significantly at 48 h after exposure to 70 mg/kg CPA. Exposure to 20 and 70 mg/kg CPA for 12 h caused a visible DNA ladder in gel electrophoresis. DNA ladder formation was increased progressively in the groups from 8 h to optimal magnitude at 12-24 h and then disappeared at 48 h after 70 mg/kg CPA. This pattern was confirmed by a quantitative evaluation of the apoptotic cells using H and E staining. Expression of Fas protein was enhanced in the thymus of rats exposed to 70 mg/kg CPA for 4-8 h as compared to control rats. These results are different from previous studies on high dose CPA and the induction of the apoptotic cell death in thymus by low or relative low doses of CPA might be a result of Fas/Fas-ligand interactions.

Animals↗
PubMed1999

Increased radiation-induced apoptosis in mouse thymus in the absence of metallothionein.

Metallothionein (MT) has been shown to protect cells from free radical induced DNA damage after exposure to copper, hydrogen peroxide and also radiation. In order to study the role of MT in radiation induced apoptosis, age-matched male control mice (C57BL/6J), MT-I overexpressing (MT-I*) and MT-null transgenic mice were exposed to whole body cobalt 60 gamma-irradiation at 0, 5, or 10 Gy, and their thymus were removed 24 h later. The basal levels of MT and zinc concentrations in the thymus were measured by 109Cadmium-heme assay and atomic absorption spectrophotometry, respectively. The MT expression after radiation was determined by immunohistochemical staining using a polyclonal antibody to MT. The extent of apoptosis in thymocytes was determined by histology (H&E stain). DNA was isolated from the thymus, and DNA fragmentation was determined by agarose gel electrophoresis. The results showed that the basal level of MT protein in MT-I* thymus was 2.4-fold higher than control mice, and that MT was inducible in both MT-I* and control C57BL6 thymus after radiation exposure. Minimal MT protein was detected in MT-null mice thymus before or after radiation, while, a significantly higher number of apoptotic cells and DNA fragmentation were found in MT-null thymus after whole body irradiation. These data demonstrated a protective role for MT in radiation-induced apoptosis in mouse thymus.

Animals↗
PubMed1999

Preparation and Characterization of Nanoscopic Organic Semiconductor of Oxovanadium Phthalocyanine.

Nanoscopic particles of oxovanadium phthalocyanine (VOPc, phase-II) with different particle sizes are prepared by aggregation of VOPc molecules in the presence of surfactants for the first time. A size effect in the region of nanoscale was observed in the UV-visible spectra. The photoconductivity of the nanoscopic VOPc is much higher than that of bulk VOPc. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Identification of a novel cardiac lineage-associated protein(cCLP-1): A candidate regulator of cardiogenesis.

We describe the isolation and characterization of a cDNA clone, called cCLP-1, that is a candidate for the previously described early cardiac-specific transcription factor BBF-1. BBF-1 binds the MEF2 (or element B) binding site within the cardiac myosin light chain 2 (MLC2) gene promoter. We used the element B sequence as a probe to screen an expression library constructed from mRNA obtained from the presumptive heart-forming regions of stage 6 chicken embryos. This yielded the cCLP-1 cDNA clone. Gel-shift analysis of stage 6 embryonic chicken protein extracts suggests that a protein that is recognized by the anti-cCLP-1 antibody binds to the same element B binding site to which BBF-1 binds. cCLP-1 mRNA was detected early in chicken development, prior to cardiac fate assignment at stage 4. The expression pattern of cCLP-1, based on whole mount in situ hybridization, coincides remarkably well with the established morphogenetic field of early heart formation. The nuclear localization of cCLP-1 is phosphorylation-dependent, suggesting that cCLP-1 may be a member of that class of transcription factors whose activity is regulated by cytoplasm to nucleus transport. Taken together, these data suggest that cCLP-1 may encode a novel transcription factor whose expression pattern is in agreement with that of the cardiogenic precursor cells of the early chicken embryo.

Amino Acid Sequence↗
PubMed1999

Low-dose whole-body irradiation induces alteration of protein expression in mouse splenocytes.

In previous studies, the stimulatory effect on immunological function and adaptive response in splenocytes were found after exposure of mice to low-dose whole-body irradiation (LD-WBI). Protein synthesis was found to be required for these responses. The present study, therefore, attempts to investigate the protein changes in mouse splenocytes after exposure to LD-WBI. Two-dimensional gel electrophoresis was used to show the alterations of proteins in nuclei, cytoplasm and extracellular fluid of the splenocytes at 4 h after mice exposed to 75 mGy X-rays. As compared to control, changed expressions of 20, 15 and 6 proteins, in sizes ranging from 10 to 69 kDa with pI of 5.0-8.2, were found in the nuclei, cytoplasm and extracellular fluid of splenocytes, respectively. One protein, shown in the cytoplasm of splenocytes of control mice, appeared in extracellular fluid of splenocytes after LD-WBI. Two proteins, shown in cytoplasm, and one protein, shown in extracellular fluid of splenocytes in control mice, appeared in the nuclei after LD-WBI. Time-course of protein synthesis varied in different proteins after LD-WBI. These results suggest that alterations of protein expressions and redistribution of proteins between intracellular and extracellular compartments occurred in the splenocytes after LD-WBI. Protein extract from LD-WBI splenocytes was fractionated by Sephadex G-100. Fractions 61-80 contained proteins able to protect lymphocytes in vitro from radiation-induced chromosome aberrations. These findings are of importance in elucidating mechanisms of immuno-enhancement and adaptive response induced by low-dose radiation. although the features and the functions of these proteins remain to be elucidated in future studies.

Animals↗
PubMed1999

Metallothionein in radiation exposure: its induction and protective role.

Since its discovery about 40 years ago, there has been a wide interdisciplinary research interest in metallothionein (MT) on its physiological and toxicological aspects. Functionally, MT is involved not only in metal detoxification and homeostasis, but also in scavenging free radicals during oxidative damage. Among over 4500 publications which can be retrieved by Medline search, only about 50 reports have been published on the relationship of MT with ionizing and UV radiation. In this review, we have evaluated critically the published data on the induced synthesis of MT by radiation, and the potential functions of MT in radiation induced cell damage. MT mRNA expression or MT synthesis was found to be induced by exposure of cells in vitro or tissues in vivo to ionizing or UV radiation. In most of the studies in animals and tissue cultures, high doses of ionizing radiation were used to induce MT, and, therefore, it is difficult to extrapolate these results to low level of repeated exposures to radiation in humans. Induced synthesis of MT is considered as one of the mechanisms involved in the adaptive response to low dose radiation exposure. The presence of MT in normal cells may provide protective effects from radiation-induced genotoxicity and cytotoxicity. However, in tumor cells, the presence of MT can result in drug and radiation resistance as well. These effects are modulated by other cellular factors, besides MT, such as antioxidants, and by the cell cycle stages in cell proliferation and differentiation.

Adaptation, Physiological↗
PubMed1999

Ventricular excitation maps using tissue Doppler acceleration imaging: potential clinical application.

OBJECTIVES: The purpose of this study is to validate the use of tissue Doppler acceleration imaging (TDAI) for evaluation of the onset of ventricular contraction in humans. BACKGROUND: Tissue Doppler acceleration imaging can display the distribution, direction and value of ventricular acceleration responses to myocardial contraction and electrical excitation. METHODS: Twenty normal volunteers underwent TDAI testing to determine the normal onset of ventricular acceleration. Two patients with paroxysmal supraventricular tachycardia and 30 patients with permanent pacemakers underwent introduction of esophageal and right ventricular pacing electrodes, respectively, and were studied to visualize the onset of pacer-induced ventricular acceleration. Eight patients with dual atrioventricular (AV) node and 20 patients with Wolff-Parkinson-White (WPW) syndrome underwent TDAI testing to localize the abnormal onset of ventricular acceleration, and the results were compared with those of intracardiac electrophysiology (ICEP) tests. RESULTS: The normal onset and the onset of dual AV node were localized at the upper interventricular septum (IVS) under the right coronary cusp within 25 ms before the beginning of the R wave in the electrocardiogram (ECG). In all patients in the pacing group, the location and timing of the onset conformed to the positions and timing of electrodes (100%). In patients with WPW syndrome, abnormal onset was localized to portions of the ventricular wall other than the upper IVS at the delta wave or within 25 ms after the delta wave in the ECG. The agreement was 90% (18 of 20) between the abnormal onset and the position of the accessory pathways determined by ICEP testing. CONCLUSIONS: These results suggest that TDAI is a useful noninvasive method that frequently is successful in visualizing the intramural site of origin of ventricular mechanical contraction.

Adolescent↗
PubMed1999

Computer simulation of random packing of unequal particles.

A Monte Carlo simulation model for the random packing of unequal spherical particles is presented in this paper. With this model, the particle radii obeying a given distribution are generated and randomly placed within a cubic packing domain with high packing density and many overlaps. Then a relaxation iteration is applied to reduce or eliminate the overlaps, while the packing space is gradually expanded. The simulation is completed once the mean overlap value falls below a preset value. To simulate the random close packing, a "vibration" process is applied after the relaxation iteration. For log-normal distributed particles, the effect of particle size standard deviation, and for bidisperse particles, the effects of particle size ratio and the volume fraction of large particles on packing density and on coordination number are investigated. Simulation results show good agreement with that obtained by experiments and by other simulations. The randomness, homogeneity, and isotropy, which have not been evaluated before for packing of distributed particles, are also examined using statistical measures.

Journal Article↗