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Biomedical subjects

Q Liu

Publications and source records attributed to Q Liu.

At least 631 records · Page 35Linked to original sources
PubMed1995

Apoptosis in histiocytic necrotizing lymphadenitis.

Cell death can now be divided into necrosis and apoptosis, which are different in their morphology, biochemistry and biological significance. The present study was designed to investigate cell death in histiocytic necrotizing lymphadenitis (HNL). The features of cell death in 10 cases of HNL were analyzed using histiomorphology, ultrastructure and in situ apoptosis detection (ApopTag) methods. Two patterns of cell death were discerned. One was apoptosis of individual cells and the other was necrosis. The first pattern could be observed in all cases and the morphological features of the dead cells were consistent with those of apoptosis, which included distinctive cell volume shrinking and chromatin condensation. The apoptotic cells and bodies could frequently be found to be phagocytosed by the histiocytes. ApopTag was positively stained in most of the morphologically apoptotic cells. By double staining, most ApopTag positive cells were found to be T lymphocytes. A previous report showed that the majority of the proliferative cells were T lymphocytes. Based on those results, if was speculated that the main pathological characteristics of HNL therefore consisted of apoptosis and the proliferation of T lymphocytes.

Adolescent↗
PubMed1995

Detection of the Epstein-Barr virus in primary gastric lymphoma by in situ hybridization.

The Epstein-Barr virus (EBV) has been shown to be associated with numerous human malignancies including Burkitt's lymphoma and nasopharyngeal lymphoepithelioma. In addition, some typical gastric adenocarcinomas were also recently reported to demonstrate EBV relevance. The present study was designed to detect EBV in primary gastric lymphoma, using the in situ hybridization (ISH) method, in which oligonucleotide probes for the EBER1 RNA and the EBV DNA W region have been used. Of the 49 cases of primary gastric lymphoma studied, which all showed B cell immunophenotype, EBER1 sequences could only be found in four cases, including two low-grade cases and two high-grade cases of histological subtypes while the number of positive cells was less than 50% of the tumor cells. In one case of low-grade mucosa associated lymphoid tissue (MALT) lymphoma, the EBER1-positive neoplastic cells were found in the regional lymph node, but the primary site of the stomach showed no positive signals. The EBV presence was further confirmed by the EBV DNA ISH. Using the ISH method, rare or occasional positive lymphoid cells (probably non-tumorous bystander cells) could be detected in 10 other cases including all histological subtypes. The present study shows that only a small proportion of primary gastric lymphoma is associated with EBV, and such positive cases could be found in both high- and low-grade histological subtypes. It is also suggested that the EBV presence in the neoplastic cells of some cases of primary gastric lymphoma is most likely a secondary phenomenon.

Adult↗
PubMed1995

Genotypic detection of Mycobacterium tuberculosis rifampin resistance: comparison of single-strand conformation polymorphism and dideoxy fingerprinting.

Detection of mutations in the rpoB gene of Mycobacterium tuberculosis can be used as an accurate predictor of rifampin resistance in the majority of strains tested. Simple but highly accurate screening methods must be developed for the detection of these mutations. Either DNA sequence analysis or single-strand conformation polymorphism (SSCP) screening can be used to detect rpoB mutations, but these techniques either are expensive or yield results that may prove difficult to interpret when used in a clinical setting. This report describes the use of dideoxy fingerprinting (ddF) as a postamplification screening method to identify rifampin-resistant genotypes. The ddF protocol was performed on the amplified rpoB fragment with no preparatory steps, thus making ddF practical for laboratories equipped for polyacrylamide gel electrophoresis. When compared with the results of SSCP analysis, ddF results were more easily interpreted and contained more sequence-dependent information that facilitated differentiation of functionally significant and silent mutations. The ddF method was used for genotypic determination of rifampin susceptibility of 20 multidrug-resistant strains of M. tuberculosis. The results of this analysis were concordant with DNA sequence analysis and conventional clinical laboratory methods.

DNA Fingerprinting↗
PubMed1995

In vivo and in vitro arginine methylation of RNA-binding proteins.

Heterogenous nuclear ribonucleoproteins (hnRNPs) bind pre-mRNAs and facilitate their processing into mRNAs. Many of the hnRNPs undergo extensive posttranslational modifications including methylation on arginine residues. hnRNPs contain about 65% of the total NG,NG-dimethylarginine found in the cell nucleus. The role of this modification is not known. Here we identify the hnRNPs that are methylated in HeLa cells and demonstrate that most of the pre-mRNA-binding proteins receive this modification. Using recombinant human hnRNP A1 as a substrate, we have partially purified and characterized a protein-arginine N-methyltransferase specific for hnRNPs from HeLa cells. This methyltransferase can methylate the same subset of hnRNPs in vitro as are methylated in vivo. Furthermore, it can also methylate other RNA-binding proteins that contain the RGG motif RNA-binding domain. This activity is evolutionarily conserved from lower eukaryotes to mammals, suggesting that methylation has a significant role in the function of RNA-binding proteins.

Amino Acid Sequence↗
PubMed1995

A review of dietary vitamin E supplementation for improvement of beef quality.

Color is a primary factor used by consumers to judge beef quality, especially freshness. Recent studies indicate that dietary supplementation of vitamin E to beef cattle increases the alpha-tocopherol concentration in muscle and its membranous subcellular fractions. The increased tissue alpha-tocopherol concentration protects not only membranal lipids but also myoglobin from oxidation. This results in delayed onset of discoloration in fresh, ground, and frozen beef and in suppression of lipid rancidity, especially in fresh, ground, and frozen beef and less so in cooked beef. Extension of beef color display life depends on dose level and duration of dietary vitamin E, muscle, and aging period. Cumulative results of experiments conducted to date indicate that beef from animals that receive 500 IU/steer daily of vitamin E for 126 d could assuredly benefit the domestic retail market by extending color display life. Implementation of this technology by the beef industry requires development of a method for rapid determination of alpha-tocopherol concentration in muscle samples collected on the day of harvest.

Animals↗
PubMed1995

Variability in human cytochrome P450 paclitaxel metabolism.

Formation of 6 alpha-hydroxypaclitaxel has been described as the primary biotransformation pathway for paclitaxel in vitro and in vivo, with additional formation of two other "minor" metabolites. Using a large group (n = 49) of human liver microsomes, and P450s heterologously expressed in cell lines, our aims were to elucidate the P450s responsible for and investigate variability in paclitaxel metabolite formation. Four metabolites of paclitaxel (6 alpha-hydroxypaclitaxel, metabolites B, C and A) were formed in vitro, via CYP2C8, 3A4, 3A4 and both 2C8 and 3A4, respectively. Although 6 alpha-hydroxypaclitaxel was predominant in the majority of livers, metabolites B and C (formed by CYP3A4) were predominant in 11/49 and 2/49 livers, respectively. Predominance of metabolite B over 6 alpha-hydroxypaclitaxel was more likely in liver microsomes from donors known to be exposed to phenobarbital (P = .009), and tended to be more likely in diseased vs. normal livers (P = .047). Formation rates for 6 alpha-hydroxypaclitaxel, A, B, and C were lower in diseased liver vs. normal liver (P < .001). Rates of formation of metabolites B and C were highly correlated with each other (r2 = .91; P < .001) and with midazolam 4-hydroxylation (r2 = .87 & 0.86, respectively; P < .001). Inhibitor experiments suggest that typical CYP3A substrates/inhibitors (e.g., cyclosporin, epipodophyllotoxins) may significantly interact with paclitaxel in vivo. In a single patient in whom plasma samples were measured on two occasions, metabolite A (the dihydroxylate) was predominant, and systemic clearance of paclitaxel was lower in a course administered 1 day vs. 6 wk after a course of fluconazole therapy. We report that 6 alpha-hydroxypaclitaxel, formed via CYP2C8, is not the predominant paclitaxel metabolite in all individuals, and that CYP3A4 catalytic activity is important to overall paclitaxel metabolism in humans.

Adult↗
PubMed1995

Genetic evidence in melanoma and bladder cancers that p16 and p53 function in separate pathways of tumor suppression.

The 9p21 region of human chromosome 9 is a hot spot for chromosomal aberrations in both cultured cell lines and primary tumors. This region contains a gene, P16 (also called MTS1, CDKN2 and p16INK4), that encodes a presumptive negative cell cycle regulator called p16. P16 is deleted or mutated at high frequency in a variety of tumor cell lines including melanoma and bladder carcinoma lines. As such, it is likely to be a tumor suppressor gene. Here we show that P16 is mutated in primary bladder carcinomas (3 of 33) and melanomas (5 of 34). These findings support studies that show P16 mutations are not solely a product of growth in tissue culture but rather are involved in formation of tumors in viva. Some bladder primary tumors and some bladder and melanoma tumor cell lines contain mutations in both P16 and P53 at frequencies that suggest that p53 and p16 function in different pathways, each of which is important in suppressing malignant transformation.

Amino Acid Sequence↗
PubMed1995

Restriction endonuclease fingerprinting (REF): a sensitive method for screening mutations in long, contiguous segments of DNA.

Restriction endonuclease fingerprinting (REF) is a modification of single-strand confirmation polymorphism (SSCP) that was developed to detect the presence of essentially all mutations in a 1-kb segment. To test REF, a 1-kb segment of the human factor IX gene was amplified with PCR and digested with each of five groups of restriction endonucleases. The endonucleases in each group were chosen so that the average size of the fragments was about 150 bp. After separate digestions, the products were mixed, 5' end-labeled with T4 polynucleotide kinase, denatured and electrophoresed under nondenaturing conditions. Each lane screened 1 kb and typically contained 68 segments (6.8 fragments per average digestion x 5 digestions x 2 strands). REF was performed with 5.6% polyacrylamide and 7.5% GeneAmp at temperatures of either 23 degrees or 8 degrees C. Point mutations resulted in the gain or loss of a restriction site in 21% of 24 test mutations (informative restriction component). In cases in which the restriction component was not informative, mutations were detected if any of the five mutation-containing restriction fragments (producing 10 single-stranded segments) displayed abnormal mobility (SSCP component). The average efficiency per single-stranded segment of the SSCP component for the 24 point mutations ranged from 49% for polyacrylamide at 23 degrees C to 68% with GeneAmp at 8 degrees C. REF detected 96% of the mutations with polyacrylamide at 23 degrees C and 100% with GeneAmp at 23 degrees or 8 degrees C. GeneAmp at 23 degrees and 8 degrees C also detected 100% of a subsequent blinded sample that contained normal controls and 27 different point mutations.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Simultaneous fine-needle aspiration and core-needle biopsy of thyroid nodules.

To evaluate the efficacy of simultaneous fine-needle aspiration (FNA) and core-needle (CN) biopsies of thyroid nodules, the clinical course and operative findings in 100 patients having both tests were reviewed. Each patient had a diagnosis made with this approach. Both specimens were adequate for diagnosis in 95 patients. In the remaining 5 patients, a diagnosis was provided by FNA in four and CN biopsy in one. FNA and CN biopsies gave the same diagnosis of either a benign nodule in 53 patients or neoplasia in 30 patients. When both FNA and CN biopsies showed a benign nodule, a nonoperative approach was taken in 43 of the 53 patients. Forty-two patients were operated on either because of biopsy findings (32) or clinical indications (10). The surgical specimens were used to determine the false positive and false negative rates, the sensitivity, specificity, and accuracy for the diagnosis of neoplasia. The false (+) and false (-) rates in diagnosing neoplasia were 33 per cent and 7 per cent for FNA, 20 per cent and 4 per cent for CN biopsy, and 20 per cent and 0 per cent for both. The sensitivity, specificity, and accuracy for FNA were 93 per cent, 67 per cent, and 83 per cent, for CN biopsy 96 per cent, 80 per cent, and 90 per cent, and 100 per cent, 80 per cent, and 93 per cent for both FNA and CN. All neoplasms were detected, and no thyroid carcinomas were missed by this combination. There was only one complication: bleeding after a CN biopsy. Combined FNA and CN biopsies allow most patients with thyroid nodules to avoid an unnecessary operation and accurately diagnose those with thyroid carcinoma. These two procedures are safe and complementary.

Adenocarcinoma, Follicular↗
PubMed1995

[A study on duration of using VCu200 intrauterine device].

OBJECTIVE: To make certain of the duration of using V-copper 200mm2 intrauterine device (VCu200 IUD). METHODS: Six hundreds and sixty six pieces of VCu200 IUD used for different time period and removed for various reasons were analyzed. The life span of VCu200 IUD depended on corrosion, fragmentation and damage of copper wire and these parameters were measured on VCu200 IUD removed. RESULTS: There were significant difference in copper wire fragmentation rate between tenth year-group and fifteenth year group which were 12.36%, 25.53% respectively (P < 0.001), and so were the expulsion rate of copper wire 2.54%, 9.57% respectively (P < 0.05). The copper loss and copper releasing rate in tenth year-group were 39.73%, 22.95%micrograms/day respectively. Copper corrosion resulted in fragmentation of copper wire which occurred the earliest in three years of use and expulsion of copper wire segment occurred after five years of use. CONCLUSION: Comparing the above results with other copper intrauterine devices, it was suggested that the suitable duration of VCu200 IUD use was ten years.

Equipment Failure↗
PubMed1995

Epidemiological survey of primary angle-closure glaucoma in Doumen.

PURPOSE: To determine the prevalence of primary angle-closure glaucoma (PACG) in Doumen Countty, Guangdong province. METHODS: Four villages from eight districts in doumen were selected by stratified, cluster and random sampling. Of a total of 1055 people aged 45 years or over, 932 (88.62%) were examined. The examination and diagnostic criterion were similar to those of shunyi survey. RESULTS: The prevalence of PACG in subjects over 45 year of eye is 0.64%, in those over 50 years of age is 0.85% in Doumen, which is significantly lower than the corresponding figure of 1.99% in shunyi (P < 0.05). CONCLUSION: This study identifies the prevalence of PACG in Doumen is lower than in Shunyi.

Aged↗
PubMed1995

[Determination of panaxadiol and panaxatriol in shihu yeguang pills].

The contents of panaxadiol and panaxatriol in Shihu Yeguang Pills manufactured by pharmaceutical works in Beijing, Jinan, Guangzhou and other places were determined by TLC-densitometry. A quantitative method has been developed to serve as a reference to quality control of these pills.

Chromatography, Thin Layer↗
PubMed1995

[A role of oblique flashlight test in screening for primary angle closure glaucoma].

PURPOSE: To study the effect of oblique flashlight test in screening for primary angle closure glaucoma. METHOD: Two hundred adults over 50 years old were sampled randomly at Doumen county of Guangdong province in 1995. 390 eyes were measured by oblique flashlight test according to grading standard photos of oblique flashlight test. Other ocular examinations consisted of intraocular-pressure measurement with Schiotz tonometer, gonioscopy, and optic disc appearance. RESULTS: The result showed 25.2% of the examined eyes had the oblique flashlight grade < or = 2, and tended to be increasing with age (x2 = 8.597, P < 0.05) and in females (x2 = 14.89, P < 0.01). Based on temporal anterior chamber angle < or = 2 (Shaffer's grade), the obligue flashlight grade < or = 2 found that occludable angle sensitivity was 91.7%, specificity was 91.5%, and 8.16% of the eyes had primary closure angle glaucoma. No patient was found in oblique flashlight grades > or = 3. CONCLUSION: This study shows that oblique flashlight test conforms to screening test needs, and plays an important role in screening for primary closure angle glaucoma. We suggest that oblique flashlight grades < or = 2 as cutoff point of screening for occludable angle.

Aged↗
PubMed1994

Activity and in vitro reassembly of the coated vesicle (H+)-ATPase requires the 50-kDa subunit of the clathrin assembly complex AP-2.

We have previously shown that the 50-kDa subunit of the clathrin assembly complex AP-2 (AP50) stoichiometrically binds to and is immunoprecipitated with the vacuolar (H+)-ATPase (V-ATPase) from clathrin-coated vesicles (Myers, M., and Forgac, M. (1993) J. Biol. Chem. 268, 9184-9186). We now report that treatment of stripped coated vesicles with cystine results in a purified V-ATPase complex lacking the AP50 polypeptide. Removal of AP50 can be reversed upon treatment of the vesicles with dithiothreitol. Removal of AP50 reduces the ATPase activity of the purified V-ATPase by 90% relative to the enzyme containing AP50. This inhibition is not reversed upon treatment of the AP50-depleted enzyme with dithiothreitol in the absence of AP50. The reconstituted V-ATPase depleted of AP50 is devoid of ATP-dependent proton transport activity. We observe further that the peripheral V1 subunits are unable to reassemble onto the integral V0 domain in the absence of AP50. The addition of purified AP-2 containing the AP50 polypeptide restores the ability of the V1 subunits to assemble with the V0 sector to give a V-ATPase complex that is functional in ATP-dependent proton transport. These results indicate that the AP50 polypeptide is necessary for both activity and in vitro reassembly of the V-ATPase complex.

Adaptor Protein Complex 2↗