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Biomedical subjects

J Cheng

Publications and source records attributed to J Cheng.

At least 163 records · Page 9Linked to original sources

Surface-enhanced raman spectra of dyes and organic acids in silver solutions: chloride ion effect.

We have recorded surface-enhanced Raman (SER) spectra of two different classes of compounds, cationic dyes and organic acids, and studied their chloride ion effects on the surface-enhanced Raman scattering (SERS) activities of the silver solution. For the positive charge dyes, rhodamine 6G (R6G) and 1,1'-dimethyl-2,2'-cyanine iodide (DECI), no SERS could be observed without the addition of chloride ions because of lack of the electrostatic interaction between the dye species and the silver particles in the silver solution. The chloride ions served to enlarge silver particles and to contribute the existence of the surface active sites, making the silver solution SERS active to the dye samples. Surface-enhanced resonance Raman scattering (SERRS) intensity of the dye molecules increased with the chloride ion concentration. After reaching a maximum intensity, a Cl- quenching effect on the intensity took place. For the organic acids, benzoic acid and p-aminobenzoic acid (PABA), SERS could be observed without the coexistence of chloride ions. The intensity of the Raman scattering did not vary significantly in the presence of small amount of chloride ion. At high Cl- concentration, quenching SERS intensity began to take effect.

4-Aminobenzoic Acid↗

Investigation of TTV by in situ hybridization in patients with chronic hepatitis.

To clarify whether TT virus (TTV) was present in liver tissues, 12 liver tissue samples from patients with chronic hepatitis positive for TTV in their serum and 11 samples from serum-negative patients were obtained by needle biopsies and investigated using in situ hybridization. Positive staining was observed in nine (75%) of 12 cases positive for TTV (serum-positive group) and three (27.3%) of 11 cases negative for TTV (serum-negative group) (P=0.061). Three kinds of staining patterns were observed: nuclear, cytoplasmic and both. In 58.3% (7/12) of the patients positive for TTV staining, the stained areas were found in both the nucleus and cytoplasm. Only cytoplasmic staining was observed in three cases from the serum-positive group. Only nuclear staining was observed in two cases from the serum-negative group. No significant differences were found in the clinical background between the in situ hybridization-positive and -negative groups, and between the serum-positive and -negative groups. The present study shows that TTV exists in the liver tissue, especially in hepatocytes, of chronic hepatitis patients and that the localization of TTV in the cell is different from case to case, although why this is so remains to be clarified.

Journal Article↗

Enamel proteins and extracellular matrix molecules are co-localized in the pseudocystic stromal space of adenomatoid odontogenic tumor.

In order to examine the functional differentiation of tumor cells of adenomatoid odontogenic tumor (AOT) as ameloblasts and to determine the participation of the extracellular matrix (ECM) in the formation of its characteristic histologic architecture, tissue samples from five cases of adenomatoid odontogenic tumor were examined by immunohistochemical staining for enamel proteins and ECM molecules. Amelogenin, enamelin, laminin, heparan sulfate proteoglycan, fibronectin, collagen type IV and type V were immunolocalized within the luminal space and along the inner rim of duct-like structures. Eosinophilic hyaline droplets within the whorled or rosette masses of tumor cells showed basically the same staining pattern as the luminal contents. High columnar tumor cells that formed duct-like structures were immunopositive for amelogenin, while the staining intensity decreased with flattening of the cells, which was a result of luminal growth. The findings suggest that the constituent cells of duct-like structures are differentiated once to ameloblasts but fail to mature further due instead to increased production of ECM molecules and due to their retention in the lumina. It is possible to regard these special structures in AOT as stromal pseudocysts.

Amelogenin↗

Inhibition of cell proliferation in HCC-9204 hepatoma cells by a c-myc specific ribozyme.

A ribozyme (RZ) gene targeting c-myc mRNA was synthesized and cloned. Cleavage reaction showed that cleavage of the RZ was efficient and specific. The RZ gene-containing retrovirus vector pDOR-RZ was transfected into HCC-9204 hepatoma cells, which constitutively express high levels of c-myc using Lipofectamine. Positively transfected cells were selected using G418. In situ hybridization showed that both pDOR-RZ and pDOR vectors had been integrated into the chromosome of HCC-9204 cells. Dot blot hybridization indicated that expression of the RZ was only evident in pDOR-RZ-transfected HCC-9204 cells. Avidin-biotin complex enzyme-linked immunosorbent assay showed that c-myc expression was down-regulated. Chromatin aggregation into compact masses, cytoplasmic vacuole degeneration, and blurring of cytoplasm structure were observed by transmission electron microscopy in HCC-9204-RZ cells. These results suggest that the use of a c-myc mRNA cleaving enzyme could be most effective in tumor cells that are highly proliferative and constitutively express high levels of c-myc.

Carcinoma, Hepatocellular↗

Optimization of TEOAE recording protocols: a linear protocol derived from parameters of a time-frequency analysis: a pilot study on neonatal subjects.

Linear and non-linear TEOAE protocols were compared in terms of nine parameters in order to define the protocol producing recordings with the highest signal quality (lowest noise and highest signal-to-noise ratio). The pilot project acquired data using ILO-92 apparatus from 220 neonates (397 ears) at the second/third day after birth in three European laboratories. A Gabor spectrogram time-frequency representation of the recordings showed considerable frequency dispersion in TEOAE latencies >4.0 ms. The data, analysed with a Wilcoxon test, indicated that a linear TEOAE protocol: (i) generates recordings of a lower noise and a higher signal-to-noise (S/N) ratio in the 2.0, 3.0, 4.0 kHz TEOAE bands; (ii) the increase in the S/N ratio can result in a decrement of the required number of TEOAE sweeps; (iii) the higher values of S/N can be used in the estimation of more robust pass-fail criteria, minimizing the percentage of false positives and negatives.

Acoustic Stimulation↗

Naltrexone: effects on motor function, speech, and activities of daily living in a patient with traumatic brain injury.

Evidence from many studies has suggested that endogenous opioid peptides participate in a number of pathophysiological responses to brain injury. This provides the rationale for the use of opioid antagonists for the enhancement of neural recovery after brain injury. A case is presented of an 18-year-old male who had loss of consciousness for 1 month after a severe brain injury. Three months of intensive rehabilitative therapies did not change his functional status. A trial of naltrexone was given while his performance in mobility, speech and overall Functional Independence Measure (FIM) scores were monitored. Results indicate an accelerated improvement in functional status and statistically improved FIM score.

Activities of Daily Living↗

Prediction of the effect of enzymes on chick performance when added to cereal-based diets: use of a modified log-linear model.

A previous study demonstrated that a log equation could be used to predict the relationship between the amount of a crude enzyme added to a diet and chick performance. The objective of the current study was to determine if a modification of the original equation, in conjunction with a computer program, would overcome some of its limitations. The modified equation was Y = A + B log (CX + 1), where Y is the estimated performance value; A is the intercept that represents the performance without enzyme supplementation; B, the slope of the equation (performance change per log unit of an enzyme in the diet), is a measure of an enzyme efficacy; C is an amplified factor; and X is the amount of enzyme in the diet. The results demonstrated that the new model more accurately predicted chick performance than that of the original equation with correlations (r) between chick performance and amount of different enzymes added to the diet ranging from r = 0.80 to 0.99 (P < 0.05). In addition, the same trends were found when the model was used to assess the efficacy of a given enzyme added to corn-, wheat-, barley-, and rye-based diets or for combinations of two dietary components (rye and wheat). The model proposed in this study provides a new means of assessing the overall efficacy of an enzyme preparation. This model could be routinely used by enzyme and livestock producers to establish the best combination of different cereals and enzymes so as to maximize net returns.

6-Phytase↗

Synergistic interaction of MEK kinase 2, c-Jun N-terminal kinase (JNK) kinase 2, and JNK1 results in efficient and specific JNK1 activation.

Mitogen-activated protein kinases (MAPKs) are activated through cascades or modules consisting of a MAPK, a MAPK kinase (MAPKK), and a MAPKK kinase (MAPKKK). Investigating the molecular basis of activation of the c-Jun N-terminal kinase (JNK) subgroup of MAPK by the MAPKKK MEKK2, we found that strong and specific JNK1 activation by MEKK2 was mediated by the MAPKK JNK kinase 2 (JNKK2) rather than by JNKK1 through formation of a tripartite complex consisting of MEKK2, JNKK2, and JNK1. No scaffold protein was required for the MEKK2-JNKK2-JNK1 tripartite-complex formation. Expression of JNK1, JNKK2, and MEKK2 significantly augmented the coprecipitation of, respectively, MEKK2-JNKK2, MEKK2-JNK1, and JNKK2-JNK1, indicating that the interaction of MEKK2, JNKK2, and JNK1 is synergistic. Finally, the JNK1 was activated more efficiently in the MEKK2-JNKK2-JNK1 complex than was the JNK1 excluded from the complex. Thus, formation of a signaling complex through synergistic interaction of a MAPKKK, a MAPKK, and a MAPK molecule like MEKK2-JNKK2-JNK1 is likely to be responsible for the efficient, specific flow of information via MAPK cascades.

Animals↗

Causation of Crohn's disease by Mycobacterium avium subspecies paratuberculosis.

Mycobacterium avium subspecies paratuberculosis (MAP) is a member of the M avium complex (MAC). It differs genetically from other MAC in having 14 to 18 copies of IS900 and a single cassette of DNA involved in the biosynthesis of surface carbohydrate. Unlike other MAC, MAP is a specific cause of chronic inflammation of the intestine in many animal species, including primates. The disease ranges from pluribacillary to paucimicrobial, with chronic granulomatous inflammation like leprosy in humans. MAP infection can persist for years without causing clinical disease. The herd prevalence of MAP infection in Western Europe and North America is reported in the range 21% to 54%. These subclinically infected animals shed MAP in their milk and onto pastures. MAP is more robust than tuberculosis, and the risk that is conveyed to human populations in retail milk and in domestic water supplies is high. MAP is harboured in the ileocolonic mucosa of a proportion of normal people and can be detected in a high proportion of full thickness samples of inflamed Crohn's disease gut by improved culture systems and IS900 polymerase chain reaction if the correct methods are used. MAP in Crohn's disease is present in a protease-resistant nonbacillary form, can evade immune recognition and probably causes an immune dysregulation. As with other MAC, MAP is resistant to most standard antituberculous drugs. Treatment of Crohn's disease with combinations of drugs more active against MAC such as rifabutin and clarithromycin can bring about a profound improvement and, in a few cases, apparent disease eradication. New drugs as well as effective MAP vaccines for animals and humans are needed. The problems caused by MAP constitute a public health issue of tragic proportions for which a range of remedial measures are urgently needed.

Animals↗

[Cloning and sequence analysis of human genomic DNA of augmenter of liver regeneration hepatitis].

OBJECTIVE: To clone the human genomic DNA of augmenter of liver regeneration (ALR) and specify the intron-exon structure. METHODS: Using human ALR cDNA sequence as a reference and BLAST path as a nucleotide homology search tool, GenBank has been searched for ALR homologous genomic DNA sequence. The intron-exon sequences were defined by the Breathnath-Chambon rule. RESULTS: The coding sequence of human ALR consists of 3 exons, and is similar to murine ALR genomic DNA structure. The human ALR genomic DNA is 1813 nt long and codes a protein of 125 amino acid residues. CONCLUSION: Human genomic DNA of ALR consists of 3 exons and 2 introns.

Base Sequence↗

Expression of human single-chain variable fragment antibody against non-structural protein 3 of hepatitis C virus antigen in e.coli.

OBJECTIVE: To express human single-chain variable fragment (ScFv) antibody against non-structural protein 3 (NS(3)) of hepatitis C virus in E.coli. METHODS: The recombinant phages were panned by NS(3) antigen which was coated in a microtiter plate. After five rounds of biopanning, 66 clones were identified specific to NS(3) antigen. E.coli host XL(1)-Blue was transformed and induced by IPTG. The specificity of ScFv was evaluated by ELISA and dot blot hybridization. RESULTS: ScFv-NS(3) DNA digestion and sequencing data showed that the ScFv gene was composed of 750bp. ELISA and dot blot hybridization demonstrated that the soluble human single-chain Fv antibody to hepatitis C virus NS(3) antigen could combine different origins of NS(3) antigen. CONCLUSION: NS(3)-ScFv antibody expressed by E.coli host XL(1)-Blue has the activity and specificity to combine different origins of HCV NS(3) antigen.

Escherichia coli↗

[Analysis of impulse response of rectangular ultrasound transducer].

A new expression for calculating the impulse response of rectangular pistonlike transducers, proper to any points of acoustic field, is presented. The radiated field of ultrasound transducer can be analyzed using impulse response method, avoiding paraxial and farfield approximation. The velocity potential at an observation point is expressed as the convolution of the excitation velocity and the impulse response. A time-amplitude shift method for the far field impulse response of small aperture transducers is presented. The radiated field of rectangular transducers is calculated through the new method and the previous method and excellent agreement is observed.

Algorithms↗

Two cases of combined liver-kidney transplantation.

OBJECTIVES: To report the clinical experiences of simultaneous hepatorenal transplantation. METHODS: We performed simultaneous hepatorenal transplantation in one patient with liver cirrhosis of hepatitis B and uremia of chronic nephritis on February 1, 1999 and one patient with liver cirrhosis of hepatitis B complicated by hepatorenal syndrome on March 12, 1999. The donors were heart arrest cases. Rapid multiple organ harvesting techniques and UW solution infusion in situ were used. Liver and kidney transplantation were orthotopic and ordinary methods, respectively. Immunosuppressive drugs consisted of cyclosporine, Cellcept, ALG and cortstco steroids. Lamividine was used on day 50 and day 40 postoperation, respectively. RESULTS: Both transplanted organs rapidly achieved normal function postoperation and the patients recovered well but suffered mild kidney rejection day 110 postoperation in No 1 patient. In No 2 patient, acute renal function failure, mental symptoms, muscle spasm, cerebral artery thrombosis, inhalation pneumonia and chronic liver graft rejection ensured sequentially but were controlled. The patients have survived for more than nine and eight months, respectively, with normal life quality. CONCLUSIONS: Combined hepatorenal transplant is a radical treatment method for liver and kidney function failure and requires more comprehensive techniques than isolated single organ transplantation. Preventing the recurrence of hepatitis B by oral lamividine may be a key to long-term survival.

Adult↗

[Persistence of hepatitis C virus type II in patient's peripheral blood B lymphocytes transformed by Epstein-Barr virus].

OBJECTIVE: To study the persistence and replication of hepatitis C virus (HCV)-RNA in human peripheral blood B cells transformed by Epstein-Barr virus (EBV) and cultured in vitro. METHODS: EBV was used for infecting B lymphocytes from one hepatitis C patient with HCV positive in the peripheral blood mononuclear cells (PBMC) and transforming them into lymphoblasts capable of being propagated indefinitely. Then, HCV RNA of the cultured cells and supernatants was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) every one month. HCV gene was typed by enzyme separating method. Electron microscopy and immunoelectron microscopy were employed to locate HCV in the cells and observe the character of its configuration. RESULTS: HCV positive-strand RNA was detected in the cultured cells for 1 year. Interestingly, the HCV positive-strand RNA was identified in supernatants and the negative-strand RNA was also observed in the cultured cells intermittently. HCV gene was type II. Electron microscopy observed HCV spherical virus-like particles with a diameter of approximately 45 nm to 70 nm, individual particles 110 nm, in the LCL cytoplasmic vesicles. CONCLUSION: HCV may exist in the cultured cell line for a longer period and reproduce in and secrete out of them. HCV locates mainly in the cytoplasm. The cell line might be useful in analyzing the mechanisms of HCV persistence in PBMC.

5' Untranslated Regions↗

[Construction of a hepatoma-targeting vector of adeno-associated virus containing human alpha-fetoprotein promoter and wild p53 gene in gene therapy of liver cancer].

OBJECTIVE: To construct plasmids that express target genes in hepatoma cell line using adeno-associated virus (AAV) vectors containing human AFP promoter. METHODS: Primers containing specific enzyme-cutting sites were designed to amplify the alpha-fetoprotein promoter (AFP promoter) from human genome. The promoter was cloned into pTR-UF5, a plasmid containing GFP reporter gene, resulting in the recombinant AAV plasmid containing the reporter gene (rAAV-AFP-GFP). Blunted ligation was used to construct the recombinant AAV vector plasmid containing human wild p53 gene (rAAV-AFP-53). The plasmid rAAV-AFP-GFP was used to transfect the AFP-expressing Hep G(2) and non-AFP-expressing 293 cell lines, respectively, to measure the function of the cloned AFP promoter. Flow cytometry was used to measure the effect of rAAV-AFP-53 on hepatoma cell line HLE. RESULTS: rAAV-AFP-53 and rAAV-AFP-GFP were verified by DNA sequencing and enzyme digestion to carry human AFP promoter. Cell transfection of rAAV-AFP-GFP showed selective expression in AFP-positive hepatoma cell lines with a transfection rate of 36.5%; rAAV-AFP-53 induced apoptosis rate was 73.88%. CONCLUSION: Two adeno-associated virus plasmids are successfully constructed that carry p53 gene and reporter gene, respectively, guided by AFP promoter. The former one shows a hepatoma-specific apoptosis-inducing effect.

Apoptosis↗

[Melanoma antigen-3 expression in human hepatocellular carcinoma].

OBJECTIVE: To investigate the expression of melanoma antigen-3 (MAGE-3) mRNA in human hepatocellular carcinoma (HCC) and probe into the theoretical feasibility that MAGE-3 antigens can be developed as a new peptide vaccine for immunotherapy in HCC patients. METHODS: The expression of MAGE-3 mRNA in HCC tissues and the adjacent non-HCC liver tissues was studied using RT-PCR in 45 HCC patients. The results were compared with those of 16 cirrhotic patients and 12 patients whose liver tissues were pathologically normal. MAGE-3 mRNA positive PCR products were DNA sequenced in 3 HCC patients. The sequenced fragments of MAGE-3 cDNA were used as template by which a [alpha(32)P] labeled probe was synthesized and employed for Southern blot analysis. HLA class I-A and -B typing of 43 HCC patients were assayed by ELISA. RESULTS: Of the 45 HCC samples, 35 (78%) expressed MAGE-3 mRNA and six HCC adjacent tissues were also positive in MAGE-3 expression. Pathological examination showed cellular heteromorphism in these adjacent tissues. The non-HCC liver tissues from cirrhosis and normal liver samples were not MAGE-3 mRNA detectable. The DNA sequence confirmed that the target gene fragment in all of the 3 samples of PCR products was MAGE-3 cDNA. Southern blotting result confirmed that of RT-PCR assay. In HCC patients, the predominant types of HLA were A(2) (53.5%), A(11) (25.6%), A(24) (20.9%), A(33) (20.9%), B(13) (28.3%), and B(35) (23.2%). MAGE-3 mRNA expression in HCC showed no correlation with the level of serum AFP and the size of the tumor. CONCLUSIONS: MAGE-3 mRNA is expressed at a high percentage of HCC samples. This tumor rejection antigen may be used as peptide vaccine for immunotherapy of HCC patients. The phenomena that some non-HCC adjacent tissues with heteromorphism can express MAGE-3 like their paired HCC tissues indicate that the expression of MAGE-3 may be an indicator in the early stage of carcinogenesis of liver tissues.

Aged↗