Biomedical subjects

G Wang

Publications and source records attributed to G Wang.

At least 739 records · Page 41Linked to original sources

PubMed1994

Stair-step artifacts in three-dimensional helical CT: an experimental study.

PURPOSE: Stair-step artifacts in helical computed tomography (CT) are associated with inclined surfaces in longitudinal sections. The authors investigated the origin and the characteristics of the artifacts. MATERIALS AND METHODS: A cone phantom and a skull were dry-scanned with a helical CT scanner, and images were reconstructed by using the half-scan interpolation algorithm with combinations of detector collimation (1 and 5 mm), table feed (1, 2, 5, and 10 mm), and reconstruction interval (1, 2, 5, and 10 mm). RESULTS: Stair-step artifacts were perceived in most instances. Stair-step artifacts arose from two sources: large reconstruction intervals and asymmetric helix interpolation, forming isoclosed curves and spirallike patterns in three-dimensional axial views, respectively. CONCLUSION: To eliminate the stair-step artifacts, both the collimation and the table feed should be less than the longitudinal dimension of the important feature on inclined surfaces, and the reconstruction interval should be less than the table feed. Adaptive interpolation may correct the artifacts.

Artifacts↗

PubMed1994

Longitudinal image deblurring in spiral CT.

PURPOSE: To assess the feasibility of digital deconvolution techniques to improve longitudinal resolution of spiral computed tomography (CT) multiplanar reformations and evaluate how technical factors in deconvolution affect longitudinal resolution, noise, and edge ringing. MATERIALS AND METHODS: Longitudinal line spread function (LSF) of the system was estimated from longitudinal reformations of transaxial spiral CT images of a step test phantom. By using the estimated LSF, longitudinal reformations of the phantom and three clinical spiral CT studies were deconvolved by the methods of Wiener filtering and constrained iterative deconvolution. Edge ringing and image noise were quantified for Wiener filtering and constrained iterative deconvolution. RESULTS: Longitudinal reformations were substantially deblurred and resolution improved after deconvolution. Anatomic boundaries in clinical images were more clearly delineated after restoration. The methods of Wiener deconvolution and constrained iterative deconvolution improved the sharpness of the phantom step boundary at the expense of increased edge ringing and image noise. CONCLUSION: In longitudinal spiral CT reformations, blurring along the longitudinal axis can be reduced by Wiener filtering or constrained iterative deconvolution.

Technology, Radiologic↗

PubMed1994

Impaired thermoregulatory cutaneous vasodilation in spontaneously hypertensive rats.

Spontaneously hypertensive rats (SHR) are more suitable to heat stroke than are normotensive controls. To determine whether hypertension impairs thermoregulatory reflex cutaneous vasodilation we observed the tail skin vasodilator responses to body heating in male SHR and normotensive Wistar-Kyoto rats (WKY) anesthetized with chloralose and urethan (80 mg/kg and 500 mg/kg ip, respectively). A pulsed-Doppler flow probe was placed on the caudal artery at its origin to monitor tail blood flow (TBF) velocity (the tail skin is the major thermoregulatory organ of the rat), and a catheter was placed in a femoral artery to monitor arterial pressure and heart rate. Internal temperature was measured via a thermistor placed approximately 10 cm down the esophagus into the gastrointestinal tract. During normothermia, TBF was not different between SHR and WKY (0.10 +/- 0.01 vs. 0.15 +/- 0.02 kHz; P > 0.05), whereas tail vascular conductance (TVC) was significantly lower in SHR vs. WKY (0.73 +/- 0.14 vs. 1.88 +/- 0.31 Hz/mmHg; P < 0.05). In response to body heating (tail remained exposed to room temperature), the increases in TBF and TVC were markedly less SHR than in WKY (0.73 +/- 0.14 kHz and 6.03 +/- 1.11 Hz/mmHg vs. 2.61 +/- 0.35 kHz and 22.48 +/- 2.69 Hz/mmHg, respectively). After lumbar sympathectomy, TBF and TVC were not different from the values observed during hyperthermia in both groups. This indicates that the impaired cutaneous vasodilation observed in SHR was not due to failure to withdraw sympathetic vasoconstrictor tone. We conclude that thermoregulatory reflex vasodilation of the cutaneous vasculature is markedly impaired in SHR.

Animals↗

PubMed1994

Antitumor polysaccharides from a Chinese mushroom, "yuhuangmo," the fruiting body of Pleurotus citrinopileatus.

A water-soluble polysaccharide, FI, and water-insoluble polysaccharides, FII and FIII were extracted from Pleurotus citrinopileatus mushrooms. After fractionation, the antitumor activity of the fractions against Sarcoma 180 implanted in mice were examined, and the following active polysaccharides were obtained: Water-soluble polysaccharides FIo: A heteropolysaccharide containing 9.8% protein, and composed of glucose, mannose, arabinose, and galactose. FA-2-b-beta: A glycoprotein consisting of glycan:protein = 40:60 w/w, with the glyco-chain composed of glucose, xylose, mannose, galactose, and fucose. FA-3: A glycoprotein consisting of glycan:protein = 50:50 w/w, and glycan moiety consisting of glucose, galactose, xylose, mannose, and fucose. Water-insoluble polysaccharides. FIII-1: Protein-containing beta-D-glucans, FIII-1-a, and -b were obtained from FIII-1 by gel filtration, composed of glucan:protein = 80:20, and 68:32 w/w, respectively. The glucan moieties of both were almost all (1-->3)-beta-D-glucan, and their molecular weights were 68 x 10(4) and 40 x 10(4). FIII-2: Protein-containing beta-D-glucans, FIII-2-a, and -b, were obtained from FIII-2 by gel filtration, with molecular weights 190 x 10(4) and 120 x 10(4), respectively. Both were almost all composed of glucan:protein = 87:13 w/w. Both glucan moieties were mainly (1-->3)-beta-D-glucan.

Amino Acids↗

PubMed1994

Antitumor active protein-containing glycans from the Chinese mushroom songshan lingzhi, Ganoderma tsugae mycelium.

A water-soluble polysaccharide, FI, extracted from the mycelium of Granoderma tsugae, was fractionated and purified by ion-exchange chromatography, gel filtration, and affinity chromatography. Sixteen polysaccharides obtained were examined for antitumor effects on Sarcoma 180 in mice. The three active polysaccharides obtained were as follows: FIo-a: A glycan-protein complex containing 9.3% protein, and having a hetero-glyco-chain of mannose and xylose. FIo-b-alpha: Molecular weight 10,000, glucan-protein complex containing 25.8% protein. The inhibition ratio was 61.8% against the solid cancer Sarcoma 180/mice; the survival ratio was more than 194% of the control group (100). FA-1-b-alpha: Molecular weight 16,000, a complex of glycan:protein = 42:58 w/w, consisting of glucose as a main component, and associated with arabinose, mannose, xylose, and galactose. This had a tumor inhibition ratio of 56% and a survival ratio of more than 182%. Comparison of active glycan with the fruiting body and mycelium: Among water-soluble polysaccharides of fruiting body, FIo-a and FA-1, with antitumor activity, were both glucogalactan-protein complexes of molecular weight 10,000, but that of mycelium was a homoglucan protein complex in FIo-b-alpha and heteroglucan protein in both FA-1-a and FA-1-b-alpha. The heteroglucan had a low tumor inhibition ratio, but caused a high survival ratio in mice.

Amino Acids↗

PubMed1994

Adolescent substance use and codependence.

This research evaluated the extent to which parental codependence was associated with adolescent substance use and other adolescent problem behaviors. The sample was comprised of 293 adolescents and their parents who were interviewed by trained intake workers. Using LISREL modeling, we found that the number of adolescent problem behaviors was associated with parental persecuting, suffering, and rescuing behaviors. Net of problem behaviors, adolescent substance use was associated with parental suffering but not with parental persecution or rescuing. As expected, there was a strong association between adolescent problem behaviors and substance use. The associations of substance use and problem behaviors with codependence were not moderated by religious preference or by being a member of a religion that teaches abstinence.

Acting Out↗

PubMed1994

Ethanol directly modulates gating of a dihydropyridine-sensitive Ca2+ channel in neurohypophysial terminals.

Ingestion of ethanol results in a decreased level of plasma vasopressin, which appears to be caused by inhibition of arginine vasopressin (AVP) release from the neurohypophysis. Activation of membrane voltage-gated Ca2+ channels plays an important role in triggering this neurohormone release. In this article, single-channel recordings are used to demonstrate that ethanol, at concentrations constituting legal intoxication, inhibits dihydropyridine-sensitive "L-type" Ca2+ channels in isolated nerve terminals of the rat neurohypophysis. Ethanol reduced the channel open probability in a concentration-dependent manner. To allow finer resolution of channel openings and to better characterize the mechanisms of ethanol action, Bay K 8644 was used to prolong the openings of L-type Ca2+ channels. In the presence of this dihydropyridine (DHP), the reduction of the channel open probability by concentrations of ethanol of 25 mM or higher could be determined to be due primarily, although not completely, to a shortening of the open duration of this L-channel. Channel conductance was unaffected by ethanol, even at high concentrations. These results are consistent with previous macroscopic data indicating that calcium channels in these peptidergic terminals are targets for ethanol action, and indicate that ethanol acts directly on the gating characteristics of the L-type channel. Furthermore, examination of open and closed state transitions, as well as Hill plot analysis, suggests that ethanol's effects on gating are consistent with the interaction of a single drug molecule with a single target site, possibly the L-channel itself.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1994

[Leishmaniasis in Karamay. XIV. Identification of promastigote isolates from naturally infected Phlebotomus major wui].

Phlebotomus major wui, an anthropophilic species, was predominant among sandflies in Karamay, Xinjiang of China. The females of this species collected in the wild and houses were detected to be infected with promastigotes. Three isolates of promastigotes obtained from P. major wui were inoculated intraperitoneally and subcutaneously into normal hamsters or BALB/c mice which developed visceral leishmaniasis later. The mean size of amastigotes in hamster viscera (smear observation) artificially inoculated with the cultured parasite originated from sandfly was significantly smaller than those in control hamster inoculated with the cultured Leishmania turanica from great gerbils in situ. The promastigotes from P. major wui hardly grew in NNN medium. In addition, 32P labeled gene gp63 was used as probe to hybridize DNA prepared from L. infantum, L. turanica and Leishmania from this sandfly showed that marked homogeneity existed between the isolates from P. major wui and L. infantum. At the present time, visceral leishmaniasis did not occur in Karamay but cutaneous leishmaniasis (CL) has been evidenced. Thus, what is the source of natural infection of P. major wui? Whether L. turanica or L. infantum is the pathogen of human CL in this area? These are interesting aspects to deal with in the further study.

Animals↗

PubMed1994

[Determination of total arsenic in food by borohydride reduction colorimetric method].

A method for determination of total arsenic in food by borohydride reduction colorimetry is presented. After samples' digestion, the arsenic is converted into trivalent arsenic by KI-thiourea under heating when the solution's acidity is more than 1.0mol/L. Trivalent arsenic is then reduced by sodium borohydride to arsine gas which can react with AgNO3 in absorbing solution to form a yellow substance whose maximum absorption wavelength is 400nm. The method was applied to the determination of total arsenic in grape wine, carp, dried shrimp, rice powder and lettuce, and the variation coefficients were 13.3%, 12.8%, 8.2%, 12.2% and 7.2%, respectively. The recoveries from dried shrimp, carp and rice powder were 98.0%-112.0%, 82.0%-98.8%, and 84.2%-115.0%, respectively. The method was also applied to the determination of arsenic in reference material rice powder NBS 1568 and the result, 0.37-0.43mg/kg, coincided with the given value 0.41 +/- 0.05mg/kg.

Animals↗

PubMed1994

[Potentiation of electroacupuncture analgesia on visceral pain by metoclopramide and its mechanism].

The present study was to investigate the effect of metoclopramide (MCP) on electroacupuncture analgesia (EAA) and its mechanism on a rabbit visceral pain model. The results showed that MCP 8mg/kg i.v. could potentiate EAA and prolong the analgesic duration. The potentiation effect could be attenuated by icv apomorphine (APO) (a mixed D1/D2 agonist). The analgesic duration was shortened by icv SKF38393 (a selective D1 agonist) or LY171555 (a selective D2 agonist). Using HPLC-ECD, we also found that the HVA content in CSF significantly increased at 20 min. after electroacupuncture (EA) or MCP 8mg/kg i.v. (P < 0.05), but the change of HVA content was not significant when EA and MCP 8mg/kg i.v. were used together. All these observations indicate that MCP have effects of potentiating EAA and prolonging analgesic duration. These effects are related to the blockade of the central DA receptor. The activations of D1 or D2 receptor is unfavourable to the expression of EA after effect.

Acupuncture Analgesia↗

PubMed1994

Clinical assessment of biplanar transesophageal echocardiography--a report of 125 cases.

One hundred and twenty-five patients with cardiovascular disease were examined by biplanar transesophageal echocardiography (BTEE), including 67 with rheumatic heart disease (7 monitored during operation), 22 with aortic diseases, 20 with congenital heart diseases, and 16 with other kinds of heart disease. The results showed that BTEE was not influenced by corpulent and pulmonary emphysema and was better than transthoracic echocardiography at imaging the interatrial septum, left atrium and left atrial appendage, thoracic aorta, and mitral artificial valve and at intraoperative monitoring. BTEE was also better than single-plane transesophageal echocardiography, because BTEE could be used to observe the heart and thoracic aorta in transverse and longitudinal planes, thus enlarging the transmission "window" as well as allowing the entire lesion to be imaged. This study suggests that BTEE will have good prospects in clinical application.

Adolescent↗

PubMed1994

The application of traditional Chinese medicine to the management of hepatic cancerous pain.

The authors summarized the application of traditional Chinese medicine to the management of hepatic cancerous pain in Beijing and Shanghai, and in Jiangsu and Zhejiang Provinces. The therapeutic principle was to invigorate blood circulation and reduce stasis and to soothe the liver and regulate qi, so as to dredge the channels and collaterals. The results were satisfactory.

Amphibian Venoms↗

PubMed1994

Transformation of Solanum dulcamara protoplasts and regeneration of transgenic plants.

We have achieved successful transformation of Solanum dulcamara protoplasts by direct DNA uptake and regeneration of transgenic plants. The plasmids pDW2 carrying CAT gene and pCaMVNEO carrying NPTII gene were used. The electroporation voltage was 1500 V, which gave a field strength of 1500 V/cm with a time decay constant of 59.4 sec. The concentration of plasmid was 20 micrograms/2 x 10(6) protoplasts. Under these conditions, a very high transformation efficiency was obtained, with relative transformation frequency being up to 12.4% and absolute transformation frequency 2.4 x 10(-4). The activity of NPTII was detected in 75% of the kanamycin resistant calli and all of the plants regenerated from resistant calli. Southern blot analysis showed that the DNA sequence of NPTII gene derived from pCaMVNEO plasmid existed in the transformed plants of S. dulcamara.

Blotting, Southern↗

PubMed1994

[The protective effects of metallothionein on membrane proteins against endothelin--electron paramagnetic resonance spin labelling study].

Using EPR spin labelling 5 NS, 16 NS (for fatty acids) and MSL (for proteins), the changes in lipid fluidity and protein conformation in the ghost erythrocyte membrane of rat treated by endothelin have been studied. The results showed that the lipid fluidity in both of the polar region and the hydrophobic core in the membranes was not altered by endothelin at the concentration of 1 x 10(-9), 1 x 10(-8) and 1 x 10(-7) mol/L, but the ratio of S/W of membrane proteins was significantly changed by endothelin at 5 x 10(-9) and 1 x 10(-7) mol/L. This means that endothelin at the dosages used did not affect the membrane lipids but did alter protein conformation. Metallothionein (1 x 10(-5) mol/L) could attenuate this change and protect membrane proteins from endothelin. However, there is no effect of metallothionein on membrane proteins.

Animals↗

PubMed1994

[Study on clinical application of expanded skin tubes].

Skin transplantation is an operative method generally used in reparative and reconstructive surgery. How to minimize the cicatrices of the donor site, how to repair larger recipient site, and how to reconstruct organs with restoration of their functions and shapes are important problems in plastic surgery. Since September 1990, we have designed a technique of expanding skin tubes for the repair of wounds and for the reconstruction of organs when larger area of skin is required while the skin of the donor site is deficient, or when the cicatrices of the donor site are to be minimized. This technique had been applied clinically in 10 cases. Clinical practice has proved that this new operative method is superior to skin grafts, transplantation of skin flaps, and the conventional technique of expanding skin and soft tissue. This paper describes the five characteristics and the theoretical basis of the technique of expansion of skin tubes.

Adolescent↗

PubMed1994

Estrogen induced peroxidase secretion from the endometrial epithelium: a possible function for the luminal enzyme.

Estrogen induced peroxidase (EIP) activity revealed as a diaminobenzidine-H2O2 product in electron micrographs is apparent within cisternae of the RER and in large dilated apical vesicles, of which only a few have been seen to open into the uterine lumen. EIP activity is infrequently present in the trans cisternae of the rather diminutive Golgi complex in uterine epithelial cells from 12-72 h after treatment with estrogen. EIP activity is, however, prominent on the surface of microvilli of epithelial cells and as deposits in the lumen. Desalted uterine fluid (72 h) isolated by rotofor (Biorad) and analysed on isoelectric focusing gels that were stained with the diaminobenzidine-H2O2 reaction, reveal the existence of at least 6 peroxidase isoelectric variants with isoelectric points between pI 3.5 and pI 5.0. In similar preparations doubly-stained by diaminobenzidine-H2O2 and silver, peroxidase positive bands are enhanced, along with other isoelectric variants in the acidic pI range. In SDS-PAGE preparations, five prominent proteins ranging from 29-115 kD are present in 72 h uterine fluid. Luminal EIP coats the surface microvilli of the reproductive tract cells, and of viable spermatozoa incubated in uterine fluid. Peroxidase coated bacteria appear to be in the process of decay, and enzyme activity is present on the surface of most spermatozoa. It is not yet determined if EIP has bactericidal, spermicidal or capacitation functions.

Animals↗

PubMed1994

Circulating killer cells in women undergoing needle-directed excisional breast biopsy.

Needle-directed excisional breast biopsy (NDBB) is performed on many women having suspicious mammograms. Only a small subset of these women (approximately 20%) will be found to have breast cancer. The goal of this study was to test the hypothesis that presence (or absence) of circulating lymphocytes able to kill cultured breast cancer-derived cell lines would discriminate the subset of women with early forms of breast cancer from those with benign breast disease. The immune status of over 200 women undergoing NDBB was ascertained at the time of biopsy from a peripheral blood sample. Use of a standard surface immunophenotyping panel able to discriminate a variety of both natural killer cells and cytotoxic T lymphocytes revealed no significant differences when compared to a group of healthy volunteers or to the normal ranges established for our laboratory. Functional assays (cytotoxicity studies) were performed in a blinded fashion on peripheral blood lymphocytes from a subset (N = 31) of these women using a panel of target cell lines. Target cells included the NK sensitive K562; the NK resistant Daudi; and two breast cancer-derived cell lines, the hormone sensitive MCF7 and MDA-MB-435 which has been shown to metastasize in immunocompromised mice. No differences were apparent among the groups with respect to ability to kill either K562 or Daudi. All individuals undergoing NDBB had an enhanced ability to kill the breast cancer-derived cell lines compared to healthy donors. Individuals with breast cancer killed, on average, twice as many MCF7 cells as than did individuals with benign breast disease whereas both groups killed approximately three times as many MDA-MB-435 cells as did healthy donors. Further, a higher proportion of the women undergoing NDBB (2-3x) had relatively high cytotoxic ability directed against the breast cancer-derived lines than was found among healthy donors. These data expand earlier observations (Hamilton et al., 1988) that women with stage I breast cancer had elevated ability to kill MCF7 to include a substantial subset of all women with suspicious mammograms.

Animals↗

PubMed1993

RAPD (arbitrary primer) PCR is more sensitive than multilocus enzyme electrophoresis for distinguishing related bacterial strains.

The RAPD (random amplified polymorphic DNA) fingerprinting method, which utilizes low stringency PCR amplification with single primers of arbitrary sequence to generate strain-specific arrays of anonymous DNA fragments, was calibrated relative to the widely used, protein-based multilocus enzyme electrophoretic (MLEE) typing method. RAPD fingerprinting was carried out on five isolates from each of 15 major groups of Escherichia coli strains that cause diarrheal disease worldwide (75 isolates in all). Each group consisted of isolates that were not distinguishable from one another by MLEE typing using 20 diagnostic enzyme markers. In our RAPD tests, three or more distinct subgroups in each MLEE group were distinguished with each of five primers, and 74 of the 75 isolates were distinguished when data obtained with five primers were combined. Thus, RAPD typing is far more sensitive than MLEE typing for discriminating among related strains of a species. Despite their different sensitivities, the same general relationships among strains were inferred from MLEE and RAPD data. Thus, our results recommend use of the RAPD method for studies of bacterial population genetic structure and evolution, as well as for epidemiology.

Bacteria↗