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Biomedical subjects

K Wang

Publications and source records attributed to K Wang.

At least 523 records · Page 29Linked to original sources
PubMed1991

Free radicals-induced abnormal chondrocytes, matrix and mineralization.A new concept of Kaschin-Beck's disease.

Free radical generating substances, including fulvic acids, mycotoxins, Fe(II), etc attack chondrocytes, causing dedifferentiation. The dedifferentiated cells synthesize and secrete abnormal collagens rich in type I instead of the normal type II. These substances also directly attack collagens in the extracellular matrix. The abnormal collagens make the matrix change from hydroxyapatite crystallization inhibiting to promoting, and give crystals of low crystallinity, high aggregation and small size. This study leads to a new concept of the development of Kaschin-Beck's Disease (KBD).

Animals↗
PubMed1990

Preliminary evaluation of color Doppler imaging for investigation of intrascrotal pathology.

Color Doppler ultrasound facilitates investigation of blood flow in addition to imaging parenchymal abnormalities. To assess the clinical use of this technique we evaluated 25 consecutive patients with indications for intrascrotal imaging. Color flow imaging added useful information in all 11 patients evaluated for chronic scrotal pain and in 6 of 7 evaluated for acute scrotal pain. In contrast, color flow ultrasound provided little additional information in 7 patients with intrascrotal masses. Color flow ultrasound imaging is a promising method that may prove to be useful for assessment of selected patients with intrascrotal pathological conditions.

Adult↗
PubMed1990

A bacterial peptide acting as a plant nuclear targeting signal: the amino-terminal portion of Agrobacterium VirD2 protein directs a beta-galactosidase fusion protein into tobacco nuclei.

Agrobacterium tumefaciens is a soil bacterium capable of transferring DNA to the genome of higher plants. Of the virulence region-encoded proteins of the tumor-inducing (Ti) plasmid of A. tumefaciens, the VirD1 and VirD2 proteins are essential for T-DNA transfer to plant cells. These two proteins have been shown to be directly responsible for the formation of T-strands. VirD2 was also shown to be firmly attached to the 5' termini of T-strands; these facts have led to its postulation as a pilot protein in the T-DNA transfer process and as a nucleus-targeting signal in plants. We have constructed a chimeric gene by fusing the virD2 gene and the Escherichia coli lacZ gene. Cell fractionation and electron microscopy studies with transgenic tobacco plants containing the VirD2-LacZ fusion protein indicate that the first 292 amino acids of VirD2 are able to direct the cytoplasmic protein beta-galactosidase to the plant nucleus. This provides an example of cross-kingdom nuclear localization between two free-living organisms: a bacterial peptide is capable of acting as a eukaryotic (plant) nuclear targeting signal.

Bacterial Proteins↗
PubMed1990

Cell-mediated immune responses to poliovirus II. Survey of delayed hypersensitivity and T-cell proliferative responses in inbred mouse strains.

Some epidemiological reports suggest a human genetic predisposition for susceptibility to the development of paralytic poliomyelitis. In a previous study of cell-mediated immune responses by mice to poliovirus (PV), we showed differences in the responses by BALB/c and C57BL/6 (B6) mice. The present study is a further analysis of the delayed hypersensitivity (DTH) and T cell proliferative (Tprlf) responses to PV in 17 different inbred strains of mice, to determine if these responses were under major histocompatibility complex (MHC) or other genetic control. Both DTH and Tprlf to PV did not correlate with MHC for responses to any of the three PV serotypes. Further, we found a lack of concordance of DTH and Tprlf responses to a given PV serotype. The cell-mediated immune responses by any one mouse strain to one PV serotype is not predictive of that mouse strain's response to another PV serotype.

Animals↗
PubMed1990

Overexpression of virD1 and virD2 genes in Agrobacterium tumefaciens enhances T-complex formation and plant transformation.

The VirD1 and VirD2 proteins encoded by an inducible locus of the virulence (vir) region of the Agrobacterium tumefaciens Ti plasmid are required for site-specific nicking at T-DNA border sites. We have determined the nucleotide sequence of a 3.6-kilobase-pair fragment carrying the virD locus from nopaline Ti plasmid pTiC58. In contrast to the previous report (Hagiya et al., Proc. Natl. Acad. Sci. USA 82:2669-2673, 1985), we found that the first three open reading frames were capable of encoding polypeptides of 16.1, 49.7, and 21.4 kilodaltons. Deletion analysis demonstrated that the N-terminal conserved domain of VirD2 was absolutely essential for its endonuclease activity. When extra copies of the virD1 and virD2 genes were present in an A. tumefaciens strain carrying a Ti plasmid, increased amounts of T-strand and nicked molecules could be detected at early stages of vir induction. Such strains possessed the ability to transform plants with higher efficiency.

Amino Acid Sequence↗
PubMed1990

The Pyridium pad test for diagnosing urinary incontinence. A comparative study of asymptomatic and incontinent women.

Eighteen women with urodynamically proven genuine stress incontinence awaiting surgery and 23 normal, asymptomatic, continent female volunteers took part in a study to compare the accuracy of a qualitative pad test with a quantitative pad-weighing test in detecting urine loss. Each woman took 600 mg of phenazopyridine hydrochloride (Pyridium, Parke-Davis) in three equally divided doses over 18-24 hours and then underwent a standardized, one-hour pad test as described by the International Continence Society. The Pyridium pad test was regarded as positive if there was any orange staining on the pad. The quantitative pad-weighing test was considered positive if there was a weight gain of 1.0 g or more at the end of the one-hour test period. All 18 patients with genuine stress incontinence had positive Pyridium pad tests, and all had pad weight gains of greater than or equal to 1.0 g (mean, 16.5). The maximum pad weight gain in the asymptomatic, continent volunteers was 0.7 g (mean, 0.1), and none was aware of any urinary leakage during the test; however, 12 (52%) had positive Pyridium pad tests. The Pyridium pad test appears 100% sensitive in detecting urine loss in symptomatic women with genuine stress incontinence, but it has a high false-positive rate in healthy, asymptomatic, continent women. If pad-weighing tests are done, the addition of Pyridium generally will not be useful, and if Pyridium is used by itself, the results may be misleading.

Aminopyridines↗
PubMed1990

[Determination of the main alkaloids in wu tou (aconite) by TLC-densitometry].

A method of TLC densitometry was established in order to determine the main alkaloids: mesaconitine, aconitine and hypaconitine in Aconite root. The powdered sample was alkalinized by ammonia and macerated with ether for 24 h. The mixture was then centrifuged, the residue was washed three times each with 2 ml of fresh ether, the combined ether extract was evaporated to dryness and then dissolved in 1 ml of dichloromethane. Standard solution and sample solution were spotted on a sillca gel GF254 plate, and developed with cyclohexane-ethyl acetate-diethylamine (8:1:1), the chromatogram was observed under UV light as dark spots. A Shimazu TLC model 910 was used for scanning at lambda s 236 nm and lambda R 350 nm by reflection mode. Linear calibration curves were obtained for the 3 constituents in the range of 2-6 micrograms. The average recoveries of masaconitine, aconitine and hypaconitine were 97.3, 96.4, 99.1% and the variation coefficients were 1.81, 1.72, 1.18%, respectively. The spots were stable for more than 24 h. Samples from various sources were analyzed.

Aconitine↗
PubMed1990

[Determination of the active ingredients in Chinese drug wuweizi (Schisandra chinensis) by TLC-densitometry].

A method of TLC densitometry was developed to determine the active ingredients (Wuweizisu A, B, C; Wuweizichun A, B; Wuweizi ester and schisanhenol) in Schisandra kernels. The samples were extracted with hexane (3 X 5 ml) for 8, 4 and 4 h respectively. The hexane extract was evaporated to dryness and then dissolved in 1 ml of methanol. Standard solutions and sample solutions were spotted on a silica gel GF254 plate, and developed with toluene-ethyl acetate (9:1) for 18 cm (for Wuweizisu A, B, C) and with toluene-ethyl acetate (4:6) for 18 cm (for Wuweizichun A, B, Wuweizi ester and schisanhenol). On examining the chromatogram under UV light the ingredients appeared as dark spots. A Shimadzu TLC model 910 was used for scanning at lambda s 260 nm and lambda R 350 nm by reflection mode. Linear calibration curves were obtained for the 7 constituents in the range of 1-5 micrograms. The average recoveries of the 7 constituents were 92.4-101.6%; the variation coefficients were 1.62-5.28%. The spots were stable for more than 24 h. This method is sufficiently simple, rapid and accurate for routine analysis.

Chromatography, Thin Layer↗
PubMed1989

Kinetic studies of mobilization of copper(II) from human serum albumin with chelating agents.

The kinetics of the mobilizing reactions of five chelating agents for human serum albumin (HSA)-bound copper(II) [Cu(II)] have been studied spectrophotometrically. The decreasing sequence of reaction rate has been determined to be EDTA greater than DTPA greater than EGTA greater than NTA greater than IDA. A group of mathematical models were established to define the mechanisms of the competitive reactions between low-molecular-weight ligand and macromolecular ligand. All reactions of the five chelating agents follow a process involving the intermediate ternary complexes: (formula; see text) The reactions of DTPA and EDTA were found to be different from those of EGTA, NTA, and IDA. In the former cases, the reactions are likely following an overlapping mechanism in which the rate constant k1 was closed to k2. The reactions involving the other three chelators are different in k1 much greater than k2.

Chelating Agents↗
PubMed1989

Needling sensation receptor of an acupoint supplied by the median nerve--studies of their electro-physiological characteristics.

We classified 50 receptor units from 10 acupoints supplied by the medium nerve. It was found that the needling stimulation mostly excited slowly adapting receptors and that the classification of acupoint receptors related closely to their location. For example, the Shanyang, Zhongchong, Shaoshang acupoints in the skin needling sensation receptors are touch or pressure receptor units; the receptors of Neiguan, Yuji, etc.; the acupoints located in deep tissue with abundant muscles, are mostly muscle spindles; the Daling acupoint might be a colgi tendon and/or pressure receptor unit. Besides a significant receptor, an acupoint contains one or more needling sensation receptor. The receptors and the afferent fibers of acupoints take part in forming and maintaining the needling sensations.

Acupuncture Points↗
PubMed1989

Correlation of intraoperative ultrasound tumor volumes and margins with preoperative computerized tomography scans. An intraoperative method to enhance tumor resection.

Twenty-two patients with primary or metastatic brain tumors were evaluated with computerized tomography (CT) and intraoperative ultrasound. Tumor volume was estimated using a geometric formula based on CT and intraoperative ultrasound measurements. In most cases, tumor margins were marked with indigo carmine injected by ventricular cannula or with Silastic ventricular catheters placed under ultrasonographic control. Nine tumors had previously been operated on and irradiated (Group A). In this group, intraoperative ultrasound tended to overestimate the tumor volume compared to CT (intraoperative ultrasound findings 141.39% +/- 37.73% of CT findings (mean +/- standard deviation]. Sixteen patients were operated on for the first time (Group B), and in this group the volume estimates were comparable (intraoperative ultrasound findings 101.69% +/- 24.65% of CT findings). The difference between the means was statistically significant (p less than 0.01). Ultrasonography improved intraoperative delineation of tumor margins, as depicted by CT, thus maximizing the extent of resection; however, with recurrent tumors, intraoperative ultrasound tended to overestimate the tumor volume. Gliosis may account for this difference.

Adolescent↗
PubMed1988

VirD proteins of Agrobacterium tumefaciens are required for the formation of a covalent DNA--protein complex at the 5' terminus of T-strand molecules.

The T-DNA transfer process of Agrobacterium tumefaciens is activated by the induction of the Ti plasmid virulence (vir) loci by plant signal molecules such as acetosyringone. Upon initiation of the T-DNA transfer process, site-specific nicks occur at the 25-bp border sequences. This cleavage leads to the generation of a free, linear ssT-DNA molecule which is bound by sequence non-specific VirE proteins. Here we present evidence for the involvement of other acetosyringone-induced proteins in the formation of a covalent complex between the T-strand and protein, designated the T-complex. Alkaline gel-electrophoretic analysis showed that proteins specifically bind to the 5' termini of nicked T-DNA molecules. The T-complex can be formed in Escherichia coli when the VirD1 and VirD2 proteins are expressed.

Amino Acid Sequence↗