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Biomedical subjects

X Dai

Publications and source records attributed to X Dai.

At least 91 records · Page 5Linked to original sources
PubMed1998

Left-ventricle boundary detection from nuclear medicine images.

We present here a new algorithm for segmentation of nuclear medicine images to detect the left-ventricle (LV) boundary. In this article, other image segmentation techniques, such as edge detection and region growing, are also compared and evaluated. In the edge detection approach, we explored the relationship between the LV boundary characteristics in nuclear medicine images and their radial orientations: we observed that no single brightness function (eg, maximum of first or second derivative) is sufficient to identify the boundary in every direction. In the region growing approach, several criteria, including intensity change, gradient magnitude change, gradient direction change, and running mean differences, were tested. We found that none of these criteria alone was sufficient to successfully detect the LV boundary. Then we proposed a simple but successful region growing method--Contour-Modified Region Growing (CMRG). CMRG is an easy-to-use, robust, and rapid image segmentation procedure. Based on our experiments, this method seems to perform quite well in comparison to other automated methods that we have tested because of its ability to handle the problems of both low signal-to-noise ratios (SNR) as well as low image contrast without any assumptions about the shape of the left ventricle.

Heart Ventricles↗
PubMed1998

Pathogen transmission in child care settings studied by using a cauliflower virus DNA as a surrogate marker.

Two regions of cauliflower mosaic virus DNA were designed as markers to study pathogen transmission in a child care home (CCH) and child care center (CCC) and in homes of CCC children. The DNA markers were stable for 1 month in the environment. The DNA markers were introduced into the environment through sensitized objects, and spread in the environment was traced by detection of the markers with polymerase chain reaction. The DNA markers spread rapidly in both the CCH and CCC after introduction and spread more rapidly in the toddler room than in the infant room of the CCC. Hand touching of contaminated areas was the major factor leading to spread of the markers. Hand washing and surface wiping decreased spread of the markers. The markers spread minimally from room to room in the CCC but were detected in the children's homes after introduction of markers in the CCC.

Adult↗
PubMed1998

[Molecular marker as an indicator in presaging prognosis of human lung adenocarcinoma].

The paper discusses 93 cases of human lung adenocarcinoma in terms of molecular-epidemiology. The relationship between p21 protein and p53 protein and proliferating cell nuclear antigen (PCNA) was analysed by immunohischemical methods. Prognosis by Cox model was used for prosnosis prediction of adenocarcinoma in human lung. Results showed that the prognosis of adenocarcinoma was poor when of p21 protein expression was positive and the relative ratio was 2.08. However, p53 protein expression was not related to the prognosis of adenocarcinoma. The higher the positive rate of PCNA was, the poorer the prognosis of adenocarcinoma oppeared, with a ratio of 3.27.

Adenocarcinoma↗
PubMed1998

[Determination of triptolide in extract from leigongteng (Tripterygium Wilfordii Hook. F.) by RP-HPLC].

A reversed-phase liquid chromatographic method has been developed and validated for the analysis of triptolide in extract from Leigongteng (Tripterygium Wilfordii Hook. F.). The drugs were eluted with petroleum-ethyl acetate on a neutral alumina cartridge and then measured by HPLC using a Hypersil C18 column and acetonitrile-water (40:60, V/V) mobile phase. Triptolide was quantified by ultraviolet absorbance at 210 nm. The method proved to be linear in the range of 0.25-4.00 mg/L with a regression coefficient of 0.9997. The lower limit of detection of triptolide was 0.1 mg/L. Intra-day and inter-day coefficients of variation of assay for triptolide were 1.9%-6.5% (n = 5) and 2.7%-7.8% (n = 5), respectively. The recoveries of the method were 89.8%-92.0%.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1998

[Yishen huanshuai recipe retard progression of chronic renal failure].

OBJECTIVE: To investigate the effect of Yishen Huanshuai recipe (YSHSR) on the progression of chronic renal failure (CRF). METHODS: Forty-six patients with CRF were divided into two groups: group A (self-controlled group, n = 18), whose treatment was subdivided into two stages. During the first stage, the patients treated with low protein diet and controlling blood pressure, while in the second stage, YSHSR was given. Group B(n = 28), whose treatment plan was similar with that of group A in second stage. The rate of progression of CRF was estimated by slope of the creatinine reciporcal (dl/mg) with time (month). RESULTS: Mean slope of the creatinine reciprocal with time from the group A during the first stage was -0.0104 +/- 0.0021, while during the second stage, it was -0.0034 +/- 0.0018. There was significant difference between them (P < 0.05). Mean slope from the group B was -0.0047 +/- 0.0020. There was also significant difference between that from the group B and that from the group A during the first stage (P < 0.05). CONCLUSIONS: Low protein and controlling blood pressure plus YSHSR therapy could markedly retard the rate of progression of CRF.

Adult↗
PubMed1998

[Determination of felodipine concentration in human plasma by GC-ECD and study of its pharmacokinetics].

A rapid, accurate and sensitive gas chromatographic method using electron-capture detector (GC-ECD) was developed for the determination of felodipine concentration in human plasma. Nimodipine was used as internal standard. The plasma samples were extracted using a mixture of ethyl ether and n-hexane (2:1) to give mean recoveries of 97.3% of felodipine. The extracts were separated by a 5% SE-30 glass packed column (2 m x 3 mm). The detection limits for felodipine was 0.25 ng.ml-1. The precisions (RSD%, n = 5) of within-day and day-to-day were less than 5.09% and 8.62%, respectively. The pharmacokinetic parameters of felodipine in ten men were investigated by this method. The concentration-time curve was fitted to a two-compartment model. Its main pharmacokinetic parameters were: T1/2 alpha = 0.76 h, T1/2 beta = 16.09 h, Cmax = 4.78 ng.ml-1, Tmax = 2.01 h, AUC = 45.2 h.ng.ml-1.

Adult↗
PubMed1998

[Isolation and identification of Agrobacterium spp. from cherry crown galls and their sensitivities to agrocin 84].

Crown galls were sampled from cherry yards of Shandong, Hebei, and Liaoning provinces. 46 pathogenic strains were isolated. Physiological and biochemical tests revealed that 4 strains were Agrobacterium tumefaciens(bio. 1) and that the other 42 strains were A. rhizogenes (bio. 2), according to the classifications and nomenclatures of the genus Agrobacterium and the species revised by Sawada et al and Bouzar. The Ti plasmids of all strains were nopaline type. All strains were sensitive to agrocin 84, which suggested that crown gall disease of cherry could be controlled by K84 strain.

Adenine Nucleotides↗
PubMed1997

Supercoil-induced extrusion of a regulatory DNA hairpin.

Bacteriophage N4 virion RNA polymerase (N4 vRNAP) promoters contain inverted repeats, which form a 5- to 7-base-pair stem, 3-base loop hairpin that is required for vRNAP recognition. We show that, contrary to certain theoretical predictions, hairpin extrusion can occur at physiological superhelical densities in a Mg2+-dependent manner. Specific sequences on the template strand are required for hairpin extrusion. These sequences define stable DNA hairpins that are relatively unreactive to single strand-specific probes. In addition, a specific stable hairpin-inducing sequence can regulate transcription in vivo. Thus, a DNA structure, in its natural environment, is involved in transcriptional regulation.

Base Composition↗
PubMed1997

Sapporo-like human caliciviruses are genetically and antigenically diverse.

The Sapporo-like human caliciviruses (HuCVs) comprise one of three genogroups of HuCVs associated with acute gastroenteritis. Phylogenetic analysis has shown that Sapporo-like HuCVs are related more closely to animal caliciviruses than to other known HuCVs. We produced 3.2 kb cDNA fragments from the 3' end to three Sapporo-like HuCVs that were associated with acute gastroenteritis in children (Houston/86, Houston/90, and London/92). Sequence analysis of the 3.2 kb cDNAs showed that two of the three viruses had a genomic organization similar to that of other Sapporo-like strains and the third strain (London/92) lacked an open reading frame overlapping the 5' end of the capsid gene. Alignment of the capsid sequences of these three strains showed 44-78% amino acid identity among the three strains. Phylogenetic analysis of the aligned sequences indicated the three strains are related but each belongs to a distinct genetic cluster. The genetic differences are associated with antigenic differences in that an enzyme immune assay (EIA) specific for the prototype Sapporo/82 strain detected the Houston/86 strain, but not the Houston/90 and London/92 strains. In vitro transcription and translation of viral cDNA containing the predicted capsid gene of Houston/90 resulted in a protein of 63 K, which is immunoprecipitated by sera from children infected with the strain. Genetically and antigenically distinct strains in the Sapporo-like HuCVs have not been described previously and the occurrence of such diverse strains in the same community likely increases the importance of these strains as a cause of illness in children.

Amino Acid Sequence↗
PubMed1997

Alveolar bone loss one year following ovariectomy in sheep.

There is little information concerning the incidence of alveolar bone loss in estrogen-deficient women. Ovariectomized sheep are valid models for study of the effects of estrogen deficiency on bone metabolism. The objective of this study was to compare alveolar bone loss in control (C) and ovariectomized sheep (OVX) at 3 and 12 months following surgery. OVX animals had decreased serum levels of 17-beta-estradiol and increased serum levels of osteocalcin, IL-6, and urinary levels of deoxypyridinoline which, taken together, suggest development of osteoporosis. The mean probing depths and percentage of sites with pocket depths 4 to 6 mm and > 6 mm were significantly greater in OVX than C at each time period and in OVX were significantly greater at 12 months that at 3 months. Gingival tissue interleukin-6 (IL-6) levels (but not the number of IL-6(+) cells) were elevated adjacent to deep periodontal pockets; however, there was no significant elevation of levels of the proinflammatory cytokines IL-1 beta and IL-8 within gingiva. Taken together, the data suggest a systemic contribution for progression of periodontal disease associated with estrogen deficiency. This may involve upregulation of systemic IL-6 synthesis and transfer to gingiva in serum, resulting in enhanced IL-6 accumulation within the gingival tissues or reduced bone density allowing for a greater amount of alveolar bone loss.

Alveolar Bone Loss↗
PubMed1997

Expression of the spinach betaine aldehyde dehydrogenase (BADH) gene in transgenic tobacco plants.

Plasmid pLS9 contains a 1.5-kb of spinach cDNA including its complete open reading frame. The 1.5-kb BADH cDNA was cut from pLS9 using restriction enzyme and was inserted into the expression cassette of plasmid pYH between the CaMV 35S promoter and polyA signal sequence. The 35S-BADH cDNA-polyA fragment of pYH was cloned into a polylinker cloning site of the binary vector pBin19. The resulting plasmid pBinBADH-S was transferred to Agrobacterium tumefacies LBA4404. The tobacco plants were transformed with strain LBA4404 containing pBinBADH-S, and more than ninety kanamycin-resistant transformants were selected. Polymerase chain reaction (PCR) detection showed that more than 60% of the transformed tobacco plants contained the foreign BADH gene. The Western blot analysis, BADH enzymatic assay, specific stain for BADH activity, and the test for salt tolerance showed that BADH gene was normally expressed in the transgenic tobacco plants. The BADH enzymes also presented in chloroplasts and cytosol of the transgenic plants. The transgenic tobacco plants having strong expression of BADH gene had strong ability to tolerate high salt stress.

Aldehyde Dehydrogenase↗
PubMed1997

Manifestation of Behcet's disease in the digestive tract.

OBJECTIVE: To study the manifestations of Behcet's disease (BD) in the digestive tract and its differential diagnosis from common inflammatory bowel diseases. METHODS: The symptoms and endoscopic, X-ray's or surgical characteristics of 24 cases of Behcet's disease with digestive tract manifestations were analysed. RESULTS: The lesions mainly occurred in tileocecum, and frequently led to hemorrhage that required surgery. The recurrent rate was as high as 77.7%. CONCLUSION: Importance should be attached to early diagnosis of BD of the digestive tract to prevent serious complications.

Abdominal Pain↗
PubMed1997

Clinical significance of serum 7S collagen and type VI collagen levels for the diagnosis of hepatic fibrosis.

OBJECTIVE: To measure serum 7S collagen (7S-C) and type VI collagen (VI-C) levels by radioimmunoassay (RIA) in Chinese patients with various liver disorders and in CCl4-treated SD rats, and to investigate the significance of the elevated levels of serum 7S-C and VI-C. METHODS: Serum 7S-C and VI-C levels were measured in 40 healthy control subjects, 168 patients with various liver disorders and non-hepatic diseases, and 52 CCl4-treated SD rats by using RIA which was developed in our hospital. RESULTS: Serum 7S-C and VI-C were significantly elevated in patients with chronic active hepatitis (CAH), liver cirrhosis (LC), hepatic cellular carcinoma (HCC) (P < 0.01 respectively), chronic persistent hepatitis (CPH), and some with non-hepatic diseases (P < 0.05). Serum 7S-C, serum laminin and hyaluronic acid were well correlated. Serum 7S-C and VI-C were not closely correlated. Both collagens were correlated with serum albumin/globulin ratio, aminotransferase and total bilirubin, not with alkaline phosphatase. In CCl4-treated SD rats, serum 7S collagen and type VI collagen levels were correlated with the degree of hepatic fibrosis. CONCLUSIONS: Serum 7S collagen and type VI collagen are useful markers for diagnosing liver fibrosis. And the combined measurement of IV-C, VI-C and other markers of connective tissue metabolism or biochemical data seems to provide additional information to predict progressive hepatic fibrosis.

Animals↗