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Biomedical subjects

F Li

Publications and source records attributed to F Li.

At least 307 records · Page 17Linked to original sources
PubMed1999

[Pollen morphology identification of five species of medicinal sanguisorba with electron microscope].

OBJECTIVE: To approach a new evidence for identifying various species of Rosaceae Sanguisorba, especially for distinguishing S. applanata from S. sitchinese. METHOD: The pollens of five species S. officinalis, S. officinalis var. longifolia, S. applanata, S. applanata var. villosa and S. sitchinese were morphologically identified with electron microscope. RESULTS: The pollens are prolate or perprolate, having six colporates and featuring sculptures of small caverns and small granules combined. The species are closed to each other in pollen morphology, bur display differences in the diameter of pollens, clarity of pore membrane and presence or absence of irregular verrucous sculptures. CONCLUSION: This paper provides a new evidence for identifying the Sanguisorba.

Microscopy, Electron, Scanning↗
PubMed1999

[Malignant external otitis: 4 cases report].

OBJECTIVE: To improve the level of diagnosis and treatment of malignant external otitis (MEO). METHOD: Four cases with MEO were reported. RESULT: Three in four cases were followed up. One patient was cured, and the others died of intracranial infection. CONCLUSION: Early diagnosis of MEO is very important for treatment. The patients of MEO with diabetes often died of intracranial infection.

Aged↗
PubMed1999

[The novel copolymer coated capillary columns of electrophoresis and their applications to separation of proteins].

The copolymer of acrylonitrile, methyl acrylate, hydroxy ethyl acrylate (ZB-004), the copolymer of acrylonitrile, methyl acrylate, hydroxy ethyl acrylate, acrylamide (ZB-014) and the copolymer of acrylonitrile, hydroxy ethyl acrylate (ZB-016) were coated on the inner surface of fused-silica capillaries by just filling the capillary with solutions containing these copolymers followed by flushing the capillary with nitrogen. The physically adsorbed layer can reduce both protein adsorption and electroosmotic flow in the pH range of 3-5. Electroosmotic flow decreased by raising the concentrations of the copolymers. Separation performance of ZB-004 layer is better than those of other two layers due to its low hydrophilicity, but with higher pH values, appreciable peak deformation and increase in electroosmosis were observed. The intra day and inter day migration reproducibility were investigated in terms of relative standard deviation (RSD) with four basic proteins at pH 4.0. The RSDs of the intra day migration times were less than 2%. The RSDs of the inter day migration times were less than 4%. At pH 5.0, the RSDs of the migration times in two ZB-004-coated capillaries made on two different days were less than 1%. Separation efficiencies of four basic proteins in a ZB-004-coated capillary which stored in a buffer (pH 4.0) for fifteen days after being used for 14 days decreased 15%. These coatings were stable and exhibited reproducible separations from intra day, inter day and inter column under acidic conditions.

Acrylamide↗
PubMed1999

Determination of selenium compounds by HPLC with ICP-MS or FAAS as selenium-specific detector.

A speciation method was developed for selenious acid, selenic acid, trimethylselenonium ion (TMSe) and selenomethionine (SeMet). Separation of the four selenium species was achieved by HPLC on an ESA Anion III anion-exchange column using aqueous mobile phase of 5.5 mmol/L ammonium citrate at pH 5.5 with a flow rate of 1.5 mL/min. Under the optimal conditions, the four selenium species were separated within 8 minutes. On-line selenium-specific detection was carried out with an inductively coupled plasma mass spectrometer (ICP-MS) or a flame atomic absorption spectrometer (FAAS). The detection limits of HPLC-FAAS were approximately rho(Se) = 1 mg/L for each compound (100 microL injection). To increase the nebulization efficiency of the ICP-MS, the Meinhard concentric nebulizer was replaced by an ultrasonic nebulizer (USN). The ICP-MS signal intensity was increased by a factor of 7 for selenious acid and 24 to 31 for TMSe, SeMet and selenic acid with the USN compared to that with the Meinhard nebulizer. The detection limits of the HPLC-USN-ICP-MS were rho(Se) = 0.08 microgram/L for TMSe, rho(Se) = 0.34 microgram/L for selenious acid, rho(Se) = 0.18 microgram/L for SeMet and rho(Se) = 0.07 microgram/L for selenic acid.

Chromatography, High Pressure Liquid↗
PubMed1999

[Longitudinal observation on a schistosome-infected snail spot as a source of infection in a mountainous village of Dali city].

AIM: To observe longitudinally the changes in survival and infection rate of Oncomelania snails in a positive snail spot in Yunnan. METHODS: A positive snail spot in a ditch in Shalimuzhuang Village, Dali City, was continually observed on the changes in the density of snail population and natural infection rate of the snails by random environmental sampling for 8 times in 4 successive years. RESULTS: During the 8 times of snail survey, living snails were found relatively stable in the ditch, in which positive snails were obtained in 6 occasions, the average infection rate being 3.99%. CONCLUSION: The density and the positive rate of snails in the mountain region remains relatively stable as a source of human infection. Elimination of the positive snail spots is necessary for controlling schistosomiasis.

Animals↗
PubMed1999

[A mutation specific polymerase chain reaction for detecting hepatitis B virus genome with A-to-C mutation at nt585].

OBJECTIVE: To investigate the prevalence of hepatitis B virus (HBV) nt585 A-to-C mutants in China. METHODS: A mutation specific polymerase chain reaction (msPCR) was established for amplifying HBV DNAs with A-to-C mutation at nt585. Two sets of primer pairs with same sequences except for one base at 3' terminus were designed and synthesized according to 48 of the known HBV genome sequences and the popular HBV subtypes, adr and adw, in China. RESULTS: 57 of HBV S gene fragments amplified by a nested PCR from different and child adult hepatitis B patients were characterized by using the msPCR. It was shown that HBV mutants with A-to-C mutation at nt585 could be confirmed. CONCLUSION: The msPCR is a specific and sensitive method for detecting the HBV nt585 A-to-C mutants.

Adult↗
PubMed1999

[Olfactory evoked potentials produced by electrical stimulation of the olfactory mucosa].

OBJECTIVE: To develop an objective olfactometric method. METHODS: Electrically evoked olfactory potentials were recorded in 20 rabbits with 0.2-4.0 mA electrical stimulations. The stimulating electrodes were placed on the olfactory and respiratory regions of the nasal mucosa. Recording electrode was placed on the scalp near the olfactory bulb. RESULTS: Electrically evoked olfactory potentials composed of triphasic negative-positive-negative peaks, named N1, P1, N2 respectively, were detected on the olfactory region. The latencies of N1, P1, N2 were 16.27 ms, 25.36 ms, 49.75 ms respectively in cribriform plate. No electrically evoked potentials were detected on the respiratory mucosa, nor did on the olfactory mucosa after olfactory neurectomy. CONCLUSION: Steady and clear electrically evoked olfactory potentials which originated from olfactory neurosystem were detected on olfactory mucosa in rabbits.

Animals↗
PubMed1999

[Measurement of surfactant in-irrigating fluid from the nasopharynx of patients with secretory otitis media].

OBJECTIVE: Dysfunction of the eustachian tube is believed to play a role in the pathogenesis of secretory otitis media (SOM). In the animal model, previous investigators have found that surfactant in the eustachian tube could decrease the eustachian tube opening pressure and improve eustachian tube functions. Because the nasopharynx is anatomically adjacent to the eustachian tube and the membrane of the nasopharynx continues to the middle ear via the eustachian tube, we hypothesized that the surfactant could also present in the nasopharynx and then designed the following experiment to confirm this hypothesis. METHODS: The concentrations of surfactants in the nasopharyngeal irrigating fluid were measured in normal control and SOM patients. RESULTS: (1) The surfactant from the SOM patients were significantly lower than that from the normal control (8.637 +/- 2.730) mg/L vs. (39.212 +/- 2.437) mg/L. (2) The concentration of surfactant from child SOM was also significantly lower than that of the normal control (8.062 +/- 2.925) mg/L vs. (39.787 +/- 2.557) mg/L. (3) The concentration of surfactant of SOM was not associated with the course of SOM. CONCLUSION: Surfactant reduction in the nasopharynx could indirectly reflect the level of the surfactant in the eustachian tube and the middle ear and influence the eustachian tube function. So surfactant reduction is one of the causative factors in SOM. The strategy of increasing surfactant in the nasopharynx and eustachian tube should be beneficial to reducing persistent secretory otitis media.

Adolescent↗
PubMed1999

[Simultaneous determination of molybdenum and chromium by artificial neural networks spectrophotometry].

In this paper, a three-layer artificial neural networks were applied to simultaneous determination of molybdenum and chromium by spectrophotometry. The apparent molar absorptivities of the complex of molybdenum and chromium are 1.4 x 10(5) L x mol(-1) x cm(-1) and 3.7 x 10(4) L x mol(-1) x cm(-1), respectively. A method has been developed for simultaneous determination of molybdenum and chromium in steel with satisfactory results. The paralysis in the procedure of training about ANN has been avoided with the improved back propagation algorithms. The simple transformation method for target vectors and criterion function convenient for selection of the parameters about the networks has been put foward.

English Abstract↗
PubMed1998

Control of apoptosis and mitotic spindle checkpoint by survivin.

Progression of the cell cycle and control of apoptosis (programmed cell death) are thought to be intimately linked processes, acting to preserve homeostasis and developmental morphogenesis. Although proteins that regulate apoptosis have been implicated in restraining cell-cycle entry and controlling ploidy (chromosome number), the effector molecules at the interface between cell proliferation and cell survival have remained elusive. Here we show that a new inhibitor of apoptosis (IAP) protein, survivin, is expressed in the G2/M phase of the cell cycle in a cycle-regulated manner. At the beginning of mitosis, survivin associates with microtubules of the mitotic spindle in a specific and saturable reaction that is regulated by microtubule dynamics. Disruption of survivin-microtubule interactions results in loss of survivin's anti-apoptosis function and increased caspase-3 activity, a mechanism involved in cell death, during mitosis. These results indicate that survivin may counteract a default induction of apoptosis in G2/M phase. The overexpression of survivin in cancer may overcome this apoptotic checkpoint and favour aberrant progression of transformed cells through mitosis.

3T3 Cells↗
PubMed1998

Differential regulation of protease activated receptor-1 and tissue plasminogen activator expression by shear stress in vascular smooth muscle cells.

Recent studies have demonstrated that vascular smooth muscle cells are responsive to changes in their local hemodynamic environment. The effects of shear stress on the expression of human protease activated receptor-1 (PAR-1) and tissue plasminogen activator (tPA) mRNA and protein were investigated in human aortic smooth muscle cells (HASMCs). Under conditions of low shear stress (5 dyn/cm2), PAR-1 mRNA expression was increased transiently at 2 hours compared with stationary control values, whereas at high shear stress (25 dyn/cm2), mRNA expression was decreased (to 29% of stationary control; P<0.05) at all examined time points (2 to 24 hours). mRNA half-life studies showed that this response was not due to increased mRNA instability. tPA mRNA expression was decreased (to 10% of stationary control; P<0.05) by low shear stress after 12 hours of exposure and was increased (to 250% of stationary control; P<0.05) after 24 hours at high shear stress. The same trends in PAR-1 mRNA levels were observed in rat smooth muscle cells, indicating that the effects of shear stress on human PAR-1 were not species-specific. Flow cytometry and ELISA techniques using rat smooth muscle cells and HASMCs, respectively, provided evidence that shear stress exerted similar effects on cell surface-associated PAR-1 and tPA protein released into the conditioned media. The decrease in PAR-1 mRNA and protein had functional consequences for HASMCs, such as inhibition of [Ca2+] mobilization in response to thrombin stimulation. These data indicate that human PAR-1 and tPA gene expression are regulated differentially by shear stress, in a pattern consistent with their putative roles in several arterial vascular pathologies.

Aorta, Abdominal↗
PubMed1998

Ubiquitin-immunohistochemical investigation of atypical Pick's disease without Pick bodies.

Six cases of atypical Pick's disease (PD) without Pick bodies (PB) were examined immunohistochemically. These cases showed severe neuronal loss with gliosis predominantly in the temporal cortices. Ubiquitin immunohistochemistry revealed ubiquitin-positive intraneuronal inclusions in the dentate gyrus and ubiquitin-positive neurites in the cerebral cortex. In the dentate gyrus, the dendrites in the stratum moleculare as well as the intraneuronal inclusions in the granular cells were positively stained. Both structures were composed of ubiquitin-positive ribosome-like granular components and a few filamentous components immunoelectron-microscopically. In the cerebral cortex, ubiquitin-positive neurites were distributed in layers II-IIIab and layers V-VI, and were considered to be the distal dendrites from the small neurons. The dendrites and perikarya of these neurons contained ubiquitin-positive components similar to those in the dentate gyrus. Some ubiquitin-positive neurites were also found in the hippocampal subiculum, amygdala and striatum. The results of this study suggest that the granular cells in the dentate gyrus and the small neurons in the cerebral cortex share common ubiquitin-related and ribosome-associated abnormalities in both the perikarya and dendrites, that the degeneration of the perforant pathway caused by the parahippocampal lesion participates in the ubiquitin related abnormalities in the granular cells, and that PD cases with and without PB have common affected neurons, as shown immunohistochemically.

Aged↗
PubMed1998

The hereditary renal cell carcinoma 3;8 translocation fuses FHIT to a patched-related gene, TRC8.

The 3;8 chromosomal translocation, t(3;8)(p14.2;q24.1), was described in a family with classical features of hereditary renal cell carcinoma. Previous studies demonstrated that the 3p14.2 breakpoint interrupts the fragile histidine triad gene (FHIT) in its 5' noncoding region. However, evidence that FHIT is causally related to renal or other malignancies is controversial. We now show that the 8q24.1 breakpoint region encodes a 664-aa multiple membrane spanning protein, TRC8, with similarity to the hereditary basal cell carcinoma/segment polarity gene, patched. This similarity involves two regions of patched, the putative sterol-sensing domain and the second extracellular loop that participates in the binding of sonic hedgehog. In the 3;8 translocation, TRC8 is fused to FHIT and is disrupted within the sterol-sensing domain. In contrast, the FHIT coding region is maintained and expressed. In a series of sporadic renal carcinomas, an acquired TRC8 mutation was identified. By analogy to patched, TRC8 might function as a signaling receptor and other pathway members, to be defined, are mutation candidates in malignant diseases involving the kidney and thyroid.

Acid Anhydride Hydrolases↗
PubMed1998

Entry and trafficking of granzyme B in target cells during granzyme B-perforin-mediated apoptosis.

In the widely accepted model of granule-mediated killing by cytotoxic lymphocytes, granzyme B entry into the target cell is facilitated by the pore forming molecule, perforin. Using indirect immunofluorescence and also direct visualization of fluorescein isothiocyanate (FITC)-conjugated granzyme B, we demonstrate internalization in the absence of perforin. Induction of the lytic pathway, however, required a second signal that was provided by perforin or adenovirus (Ad2). The combination of agents also resulted in a dramatic relocalization of the granzyme. Microinjection of granzyme B directly into the cytoplasm of target cells resulted in apoptosis without the necessity of a second stimulus. This suggested that the key event is the presence of granzyme B in the cytoplasm, and that when the enzyme is internalized by a target cell, it trafficks to an intracellular compartment and accumulates until release is stimulated by the addition of perforin. We found that the proteinase passed through rab5-positive vesicles and then accumulated within a novel compartment. On the basis of these results, we propose a new model for granzyme-perforin-induced target cell lysis in which granzyme B is subjected to trafficking events in the target cell that control and contribute to cell death.

Adenoviridae↗
PubMed1998

Regional quantitative analysis of tau-positive neurons in progressive supranuclear palsy: comparison with Alzheimer's disease.

In patients with progressive supranuclear palsy (PSP), various tau-positive abnormal structures are found in the cerebral cortex as well as in the subcortical nuclei. Similar tau-positive abnormalities are also identified in cortico-basal degeneration (CBD). It is therefore questionable as to whether PSP can be neuropathologically differentiated from CBD. It also remains nuclear whether neurofibrillary tangles (NFT) in the cerebral cortex of PSP patients consist of PSP-NFT or concomitant Alzheimer's disease (AD)-NFT, although there have been some reports suggesting that PSP- and AD-NFT are different with respect to distribution pattern and biochemical character. In this study, a regional quantitative analysis of the distribution and antigenicity of tau-positive neurons (TPN) was performed in PSP cases and compared with that in AD cases. TPN consisted of NFT with tangle-formation and pretangle neurons (PN) without tangle-formation. In addition, NFT were subdivided into mature and immature NFT according to the difference of staining properties with anti-tau-related antibodies. The comparison of the TPN of the PSP cases with those of the AD cases revealed that the degree of tangle-formation in the TPN of AD was similar in all of the examined regions, while that in the TPN of PSP varied according to the region and case. Moreover, the NFT in the PSP and AD cases had different distributions according to the cortical layer and subnucleus, even in the common predilection sites of PSP and AD, suggesting that NFT in these regions of the PSP cases consist mainly of PSP-NFT. In addition, the PSP cases could be divided into two groups according to the difference of the tangle-formation of TPN; group I with typical PSP pathology and group II with atypical PSP pathology similar to CBD. This suggests that there is a continuity between PSP and CBD with respect to the distribution and antigenicity of TPN.

Aged↗
PubMed1998

A reduction-pyrolysis-catalysis synthesis of diamond

Diamond powder was synthesized through a metallic reduction-pyrolysis-catalysis route with the reaction of carbon tetrachloride and sodium at 700 degreesC, in which the sodium was used as reductant and flux. This temperature is much lower than that of traditional methods. The x-ray powder diffraction patterns showed three strong peaks of diamond. The Raman spectrum showed a sharp peak at 1332 inverse centimeters, which is characteristic of diamond. Although the yield was only 2 percent, this method is a simple means of forming diamond.

Journal Article↗