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Biomedical subjects

Q Liu

Publications and source records attributed to Q Liu.

At least 667 records · Page 37Linked to original sources
PubMed1994

Experimental high-frequency ultrasound can detect graft rejection after small bowel transplantation.

Early diagnosis of graft rejection after small bowel transplantation (SBT) can allow prompt institution of vigorous immunosuppressive therapy, with resultant reversal of the rejection process. The current method for graft monitoring is random mucosal biopsy from a stomal site or through an endoscope. However, because early rejection often has a patchy distribution, it could be missed by random biopsy. We hypothesized that the pathological process of rejection would alter acoustic impedance of the tissue and thus change the ultrasonic patterns of the graft intestinal wall. If this hypothesis is correct, then high-frequency endoscopic ultrasound (US) could be used to monitor the entire transplanted bowel and guide the biopsy, with improved yields. This hypothesis was tested in a rat orthotopic SBT model. Sixty-two intestinal specimens (9 isografts, 12 allografts treated with cyclosporine A [CsA], 22 untreated allografts, and 19 intestines from normal rats) were collected for in vitro transluminal US imaging (30 MHz) and histopathologic study. The echo pattern of normal rat intestinal wall consisted of five echo layers that correlated spatially with the histological layers: the innermost hyperechoic layer 1, plus hypoechoic layer 2, corresponded to the mucosa; hyperechoic layer 3, the submucosa; anechoic layer 4, the muscularis propria; and hyperechoic layer 5, the serosa. The isografts and CsA-treated allografts were identical histologically and ultrasonically to normal intestine. However, the echo patterns of the untreated allografts had progressive loss of architectural stratification, with worsening rejection. The change began with patchy indistinctness and disruption of hyperechoic layers 1, 3 and 5, and progressed to total obliteration of the layers, with the intestinal wall becoming a nonstratified hypoechoic structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

An acylated flavone C-glycoside from Glycyrrhiza eurycarpa.

A new acylated flavone C-glycoside, apigenin 6-C-alpha-L-rhamnopyranoside-8-C-[6"-(3-hydroxy-3-methyl-glutaroyl )-beta-D-glucopyranoside], was isolated from rhizomes of Glycyrrhiza eurycarpa and its structure was established on the basis of spectroscopic data.

Apigenin↗
PubMed1994

Flavonol glycosides from Cephalocereus senilis.

A new flavonol tetraglycoside, together with two known flavonol glycosides, kaempferol 7-rhamnoside and kaempferol 3-rhamnosyl(1-->6) galactoside-7-rhamnoside, were isolated from fresh plant material of Cephalocereus senilis. The structure of the new compound was established as kaempferol 3-O-beta-D-glucopyranosyl(1-->2)-O-[alpha-L-rhamnopyranosyl (1-->6)]-beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranoside based on spectroscopic data. The whole plant flavonoid chemistry was strikingly different from that found previously in chitin-treated cell suspension cultures of the same plant.

Carbohydrate Sequence↗
PubMed1994

Analysis of the p16 gene (CDKN2) as a candidate for the chromosome 9p melanoma susceptibility locus.

A locus for familial melanoma, MLM, has been mapped within the same interval on chromosome 9p21 as the gene for a putative cell cycle regulator, p16INK4 (CDKN2) MTS1. This gene is homozygously deleted from many tumour cell lines including melanomas, suggesting that CDKN2 is a good candidate for MLM. We have analysed CDKN2 coding sequences in pedigrees segregating 9p melanoma susceptibility and 38 other melanoma-prone families. In only two families were potential predisposing mutations identified. No evidence was found for heterozygous deletions of CDKN2 in the germline of melanoma-prone individuals. The low frequency of potential predisposing mutations detected suggests that either the majority of mutations fall outside the CDKN2 coding sequence or that CDKN2 is not MLM.

Base Sequence↗
PubMed1994

A P1-based physical map of the region from D17S776 to D17S78 containing the breast cancer susceptibility gene BRCA1.

BRCA1, a breast and ovarian cancer susceptibility locus, has been isolated and maps to 17q21. A physical map of the BRCA1 region which extended from the proximal boundary at D17S776 to the distal boundary at D17S78 was constructed and consists of 51 sequence tagged sites (STSs) from P1 and YAC ends, nine new short-tandem repeat (STR) polymorphic markers, and eight identified genes. The contig, which spans the estimated 2.3 Mb region, contains 29 P1s, 11 YACs, two BACs, and one cosmid. Based on key recombinants in two linked families, BRCA1 was further localized to a region bounded by D17S1321 on the proximal side and D17S1325 on the distal side. Within this estimated 600 kb region, the contig was composed completely of P1s and BACs ordered by STS-content mapping and confirmed by DNA restriction fragment fingerprinting.

Base Sequence↗
PubMed1994

Parameters affecting the sensitivities of dideoxy fingerprinting and SSCP.

The goals of the present experiments are (1) to improve dideoxy fingerprinting (ddF) and (2) to utilize ddF as a tool to evaluate the relative merits of different conditions for single-strand conformation polymorphism (SSCP). ddF is performed by electrophoresing one dideoxy termination reaction through a nondenaturing gel. The ddF pattern can be divided into a "dideoxy component" and an "SSCP component". If dideoxy CTP (ddCTP) is utilized for the termination reaction of ddF, the dideoxy component is abnormal when an extra segment is produced by a sequence change that creates an extra C or when a segment is eliminated by a change of C to another base. All subsequent segments produced by the termination reaction constitute the SSCP component that contains the mutation in a nested series of ddCTP termination products. The SSCP component is informative if abnormal mobility is detected in one or more of the segments. Herein, we utilize 84 different single-base changes in the human factor IX gene to examine the effects of gel matrix, temperature, and different primers on the sensitivity of ddF. The effects of glycerol and cross-linker ratio were examined on fewer mutations. The following conclusions emerge: 1. The sensitivity of the dideoxy component is invariant, but the sensitivity of the SSCP component can vary greatly with gel matrix, temperature, segment size, and sequence context. 2. For a given segment containing a mutation, it is likely that a mobility shift will be seen under some conditions but not under other conditions. By examining the mobility of the SSCP component in > 2200 segments, it was found that some conditions are statistically more likely to result in altered mobility, thereby increasing the average sensitivity of mutation detection by ddF or conventional SSCP. 3. GeneAmp and MDE gels are superior to polyacrylamide gels and electrophoresis at 8 degrees C is superior to electrophoresis at 23 degrees C. GeneAmp at 8 degrees C provided the highest SSCP component efficiency of all conditions tested; all 84 hemizygotes and 40 heterozygotes were detected readily by ddF under these conditions. 4. The segments that terminate near the mutation site are likely to show an abnormal mobility on polyacrylamide gels at 23 degrees C. 5. The likelihood of mobility shifts decreases with segment size, but sequence context can have a major effect on SSCP component efficiency.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Sequence↗
PubMed1994

UTP: alpha-D-glucose-1-phosphate uridylyltransferase of Escherichia coli: isolation and DNA sequence of the galU gene and purification of the enzyme.

The galU gene of Escherichia coli, thought to encode the enzyme UTP:alpha-D-glucose-1-phosphate uridylyltransferase, had previously been mapped to the 27-min region of the chromosome (J. A. Shapiro, J. Bacteriol. 92:518-520, 1966). By complementation of the membrane-derived oligosaccharide biosynthetic defect of strains with a galU mutation, we have now identified a plasmid containing the galU gene and have determined the nucleotide sequence of this gene. The galU gene is located immediately downstream of the hns gene, and its open reading frame would be transcribed in the direction opposite that of the hns gene (i.e., clockwise on the E. coli chromosome). The nucleotide sequences of five galU mutations were also determined. The enzyme UTP:alpha-D-glucose-1-phosphate uridylyltransferase was purified from a strain containing the galU gene on a multicopy plasmid. The amino-terminal amino acid sequence (10 residues) of the purified enzyme was identical to the predicted amino acid sequence (after the initiating methionine) of the galU-encoded open reading frame. The functional enzyme appears to be a tetramer of the galU gene product.

Amino Acid Sequence↗
PubMed1994

Competitive reverse transcriptase-polymerase chain reaction using a synthetic internal RNA standard to quantitate transcripts for leukocyte-derived hormones.

Leukocytes synthesize a variety of hormones that were once thought to be unique products of endocrine tissues. Understanding the regulation of leukocyte-derived hormone synthesis requires an accurate means for measuring steady-state expression of specific mRNA transcripts. Here we describe a competitive reverse transcriptase-polymerase chain reaction (RT-PCR) technique to accurately quantitate macrophage-derived insulin-like growth factor-I (IGF-I) mRNA, and demonstrate the utility of this approach for measuring expression of leukocyte-derived hormone transcripts. A riboprobe was constructed to generate approximately 1 kb of synthetic competitor IGF-I RNA (exons 1 and 3-6) that differed from cellular IGF-I RNA by insertion of 122 bp of beta-actin RNA. One set of oligonucleotide primers could thus be used to simultaneously reverse transcribe and amplify both 144 bp of cellular (exons 3 and 4) and 266 bp of competitor IGF-I RNA. Densitometric scanning of the PAGE-separated PCR products revealed that the ratio of competitor to cellular amplified DNA bore a linear relationship (r2 > or = 0.98) to the amount of competitor RNA for both rat liver and splenocytes. However, rat liver contained 104 x 10(6) IGF-I molecules per microgram of total cellular RNA compared to only 2 x 10(6) IGF-I molecules for splenocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[The primary observation of effect on immune function of human body by YAG laser tonsillocoagulation].

Tonsillocoagulation was performed on 50 patients with chronic tonsillitis by virtue of YAG Laser. The patients' serum IgG, IgA, IgM, C3level and some acute phase reactant proteins (APRPs) including alpha 1-AGP, alpha 1-AT, Tf were measured pre- and postoperatively. In addition, tonsillar morphology was observed with light and electron microscope before and after tonsillocoagulation. Following up the patients for six to twelve months, we discovered that their immune function remained normal and that their symptoms of chronic tonsillitis had been controlled, it suggests that YAG Laser tonsillocoagulation can be a practical therapy for chronic tonsillitis.

Acute-Phase Proteins↗
PubMed1994

[Mapping of face and extremity skin cleavage lines in Chinese adult cadavers].

On fresh Chinese adult cadavers, which were obtained within 6 hours of sudden death, multiple skin holes of 1 cm apart were made with a conical steel punch of a diameter of 5 mm. Chinese ink was dipped into the wounds, which presently appeared to be rhomboid slits. Mapping of the directions of these rhomboid slits gave rise to cleavage lines of that area. This paper presents the skin cleavage lines of the face and extremities in Chinese adult cadavers.

Adult↗
PubMed1994

[A study on pulmonary artery compliance and hemodynamics in patients with lung-distention].

A simultaneously comparative study on pulmonary artery compliance (Cpa) and pulmonary artery mean pressure (PAMP) in 89 patients with Lung-Distention in TCM by impedance pulmonary rheogram, tricuspid valve echocardiogram and right heart catheterization. Then according to Syndrome Differentiation of TCM, Lung-Distention was sub-divided into four groups. The results showed that PAMP were gradually increased and Cpa decreased in these groups. It revealed that the pulmonary circulation of Lung-Distention patients has disturbed.

Adult↗
PubMed1994

[Point mutation of K-ras gene in pancreatic carcinoma].

Direct sequencing using Taq enzyme was established for determination of point mutation of K-ras gene at codon 12 in 9 wax samples of pancreatic carcinoma (PC) and 1 of islet cell tumor. Point mutation occurred in 5 of 9 samples of PC and manifested two types of mutation, CCA-->CGA in 4 and CCA-->CAA in 1. The changes of amino acid included changes of glycine to alanine and glycine to valine. The causes of mutation frequency and the content differed from that of foreign reports were analysed in addition to the significance of determining point mutation of K-ras gene at codon 12.

Adenocarcinoma↗
PubMed1994

[Experiences in thumb and finger reconstruction].

24 cases (25 thumbs) of thumb reconstruction and 14 cases (10 fingers) of finger reconstruction by second toe transplantation, 11 cases of thumb reconstruction by the big toe-nail flap, and 1 case of "hand" reconstruction by both second toes are presented. 48 cases (52 fingers and thumbs) are successful. Functions and aesthetic results are satisfactory.

Adolescent↗
PubMed1994

Does the [3H]mepyramine binding site represent the histamine H1 receptor? Re-examination of the histamine H1 receptor with quinine.

Mepyramine is a potent H1 receptor antagonist, and [3H]mepyramine generally is used to label histamine H1 receptors. However, we found that [3H]mepyramine labeled not only the H1 receptor but also a [3H]mepyramine binding protein (MBP) in the liver, which protein appears to be related to the subfamily of debrisoquine 4-hydroxylase (cytochrome P450IID) isozymes. The binding of [3H]mepyramine to the cloned H1 receptor was not affected by 1 microM quinine, an inhibitor of debrisoquine 4-hydroxylase. On the other hand, the binding to MBP in the liver membranes was completely inhibited by 1 microM quinine. These data indicate that the labeling by [3H]mepyramine of H1 receptors and MBP can be completely separated with 1 microM quinine. The majority of [3H] mepyramine binding sites in the cerebral cortex, thalamus and hypothalamus, hippocampus, heart, aorta, lung and spleen were H1 receptors. On the other hand, almost all [3H]mepyramine binding sites in the liver and kidney were MBP. Both H1 receptors and MBP were expressed in the stomach, ileum, cerebellum and adrenal gland. Kd values of [3H]mepyramine for membranes from the cerebellum and stomach in the presence of quinine, which tissues contain both H1 receptors and MBP, approached that value of the cloned H1 receptor. The improved [3H]mepyramine binding assay using quinine is a precise method to characterize H1 receptors by the separate determination of H1 receptors and MBP.

Animals↗