Biomedical subjects

Y Tang

Publications and source records attributed to Y Tang.

At least 289 records · Page 16Linked to original sources

PubMed1997

Increase of calcitonin gene-related peptide (CGRP) release and mRNA levels in endotoxic rats.

Previously we showed that calcitonin gene-related peptide (CGRP) is released into the circulation during pathogenesis of septic shock in humans and endotoxicosis in rats and pigs. The present study examines the changes of both CGRP release and synthesis during endotoxicosis in rats. Endotoxin was administered as a bolus (5 mg/kg,i.v.) to rats lightly anesthetized with ether. Blood samples and lumbar dorsal root ganglia (DRG), neuronal cell bodies synthesizing CGRP, were taken from rats at 0, .5, 3, or 8 h after endotoxin administration. CGRP levels in plasma and the steady-state levels of mRNA for CGRP in DRG were determined by methods of radioimmunoassay and semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR), respectively. Endotoxin elevated plasma CGRP by 62%, but not mRNA at .5 h. Endotoxin increased plasma CGRP by 142% and CGRP mRNA in DRG by 36% at 3 h, and further increased plasma CGRP by 216% and CGRP mRNA in DRG by 88% at 8 h. The data suggest that both CGRP expression and release in sensory nerves are increased during development of endotoxicosis in rats. CGRP synaptic transmission may be maintained during the course of endotoxicosis in rats. DRG undergo an elevation of CGRP expression in response to endotoxicosis, presumably as an adaptation of CGRP release during the inflammation. CGRP, because of its extremely high potency in hypotensive, tachycardiac and immunosuppressive effects, may play an important role in the pathogenesis of septic shock.

Animals↗

PubMed1997

Comparison of three methods for age-grading of female neotropical phlebotomine sandflies.

Changes in appearance of the accessory glands (AG), ovaries (OV) and the absence or presence of crease marks at the edges of the genital atrium armature (GA) were compared as methods to age-grade female laboratory-bred (Lutzomyia migonei) and wild-caught (Lu.youngi, Lu.spinicrassa, Lu.ovallesi) Neotropical sandflies. Dissections at different physiological stages revealed that all parous and high proportions of nulliparous (4/38) unmated, 12/12 mated) females showed similar residual AG secretions. Hence AG appearance (nullipars with AG translucent, versus yellowish opaque granulated AG previously regarded as signs of parousness) is unreliable for age-grading. Readily recognizable changes in both GA (98% creased) and the OV (100% yellowish with loose ovarioles) indicated that these organs could be employed to discriminate between nulliparous and parous females. Despite finding one misdiagnosed female (a nullipar having creased GA indicative of parity), the GA method of age-grading is recommended because females may be examined satisfactorily at any stage of the gonotrophic cycle. Moreover, the GA characteristics of pickled or dry preserved sandflies as well as fresh slide-mounted specimens can be determined easily. Among sixty-five wild-caught Lutzomyia females dissected (mostly Lu.spinicrassa and Lu.youngi), the proportions of specimens yielding preparations suitable for examination were 97% for GA, 89% for OV, but only 58% for AG, which reinforces GA as the preferred character for age-grading.

Aging↗

PubMed1997

Control of immunodeficiency and lymphoproliferation in mouse AIDS: studies of mice deficient in CD8+ T cells or perforin.

CD8+ T cells were previously shown to be important in preventing lymphoproliferation and immunodeficiency following infection of murine AIDS (MAIDS)-resistant mice with the LP-BM5 mixture of murine leukemia viruses. To further evaluate the mechanisms contributing to MAIDS resistance, we studied mice lacking CD8+ T cells or deficient in perforin due to knockout of the beta2-microglobulin (beta2M) or perforin gene, respectively. In contrast to wild-type, MAIDS-resistant controls, B10.A mice homozygous for the beta2M mutation and B10.D2 mice homozygous for the perforin mutation were diagnosed as having MAIDS by 5 to 8 weeks after infection by the criteria of lymphoproliferation, impaired proliferative responses to mitogens, and changes in cell populations as judged by histopathology and flow cytometry. Unexpectedly, there was no progression of lymphoproliferation through 24 weeks, even though immune functions were severely compromised. Expression of the defective virus responsible for MAIDS was enhanced in spleens of the knockouts in comparison with wild-type mice. These results demonstrate that perforin-dependent functions of CD8+ T cells contribute to MAIDS resistance but that other, non-CD8-dependent mechanisms are of equal or greater importance.

Animals↗

PubMed1997

Kinase-deficient Pak1 mutants inhibit Ras transformation of Rat-1 fibroblasts.

Among the mechanisms by which the Ras oncogene induces cellular transformation, Ras activates the mitogen-activated protein kinase (MAPK or ERK) cascade and a related cascade leading to activation of Jun kinase (JNK or SAPK). JNK is additionally regulated by the Ras-related G proteins Rac and Cdc42. Ras also regulates the actin cytoskeleton through an incompletely elucidated Rac-dependent mechanism. A candidate for the physiological effector for both JNK and actin regulation by Rac and Cdc42 is the serine/threonine kinase Pak (p65pak). We show here that expression of a catalytically inactive mutant Pak, Pak1(R299), inhibits Ras transformation of Rat-1 fibroblasts but not of NIH 3T3 cells. Typically, 90 to 95% fewer transformed colonies were observed in cotransfection assays with Rat-1 cells. Pak1(R299) did not inhibit transformation by the Raf oncogene, indicating that inhibition was specific for Ras. Furthermore, Rat-1 cell lines expressing Pak1(R299) were highly resistant to Ras transformation, while cells expressing wild-type Pak1 were efficiently transformed by Ras. Pak1(L83,L86,R299), a mutant that fails to bind either Rac or Cdc42, also inhibited Ras transformation. Rac and Ras activation of JNK was inhibited by Pak1(R299) but not by Pak1(L83,L86,R299). Ras activation of ERK was inhibited by both Pak1(R299) and Pak1(L83,L86,R299), while neither mutant inhibited Raf activation of ERK. These results suggest that Pak1 interacts with components essential for Ras transformation and that inhibition can be uncoupled from JNK but not ERK signaling.

Animals↗

PubMed1997

Liver T2-weighted MR imaging: comparison of fast and conventional half-Fourier single-shot turbo spin-echo, breath-hold turbo spin-echo, and respiratory-triggered turbo spin-echo sequences.

PURPOSE: T2-weighted spin-echo (SE) magnetic resonance imaging in the liver was compared with four sequences: fast and conventional half-Fourier single-shot turbo SE (HASTE) and breath-hold and respiratory-triggered turbo SE. MATERIALS AND METHODS: In 58 patients with focal liver lesions, imaging was performed with a 1.5-T magnet and a phased-array coil. Images obtained with fast HASTE conventional HASTE, breath-hold turbo SE, and respiratory-triggered turbo SE were compared. Results of quantitative, qualitative, and receiver operating characteristic analyses were compared. RESULTS: Lesion-to-liver contrast for solid tumors was significantly higher with the fast HASTE and respiratory-triggered turbo SE sequences than with the conventional HASTE and breath-hold turbo SE sequences (P < .01) and for cystic lesions was significantly higher with the conventional and fast HASTE sequences than with the breath-hold or respiratory-triggered turbo SE sequences (P < .01). Artifacts were negligible on all fast and conventional HASTE images. In receiver operating characteristic analyses, diagnostic performance was significantly higher with the fast HASTE and respiratory-triggered turbo SE sequences than with the conventional HASTE and breath-hold turbo SE sequences (P < .01). CONCLUSION: Images obtained with the fast HASTE sequence were free from motion artifacts, and observer diagnostic performance was similar to that with the respiratory-triggered turbo SE sequence.

Adolescent↗

PubMed1997

Focal liver masses: characterization with diffusion-weighted echo-planar MR imaging.

PURPOSE: To evaluate diffusion-weighted echo-planar magnetic resonance (MR) imaging for improving the specificity of characterization of liver tumors. MATERIALS AND METHODS: Diffusion-weighted echo-planar imaging was performed with a 1.5-T whole-body imager with use of a body phased-array coil in 51 patients with 59 hepatic masses (41 malignant tumors, nine hemangiomas, and nine cysts). Apparent diffusion coefficient (ADC) values were obtained with two motion-probing gradients (b = 30 and 1,200 sec/mm2) during each of the breath-hold periods, and an ADC map was constructed. The T2 was derived from spin-echo echo-planar images with echo times of 47 and 99 msec. RESULTS: The ADC value of malignant masses (1.04 x 10(-3) mm2/sec) was significantly lower (P < .01) than that of benign masses (hemangiomas [1.95 x 10(-3) mm2/sec] and cysts [3.05 x 10(-3) mm2/sec]), although the T2s showed considerable overlap. A small amount of overlap in ADC values occurred among malignant tumors, hemangiomas, and cysts. ADC values of two cystic masses from ovarian carcinomas were within the range of those of hemangiomas. CONCLUSION: These preliminary results indicate that diffusion-weighted MR imaging can be useful in characterizing focal liver masses. With the exception of cystic metastatic tumors, the technique may be especially useful in tumors that appear markedly hyperintense on T2-weighted images due to a long T2.

Adult↗

PubMed1997

Antiinflammatory effect of Forsythia suspensa Vahl and its active fraction.

This study was carried out to elucidate the antiinflammatory effect of 70% methanol extract obtained from the dried fruit of Forsythia suspensa Vahl and its active principles. F. suspensa was extracted with 70% methanol and freeze-dried to give a powdered extract. The methanol extract was then dissolved in water and extracted with n-hexane, and the n-hexane fraction was evaporated to dryness under vacuum; the water fraction was freeze-dried to give a powdered extract. The antiinflammatory activity of the extract and fractions was investigated on acetic acid-induced vascular permeability and writhing symptoms in mice, as well as on carrageenin-induced edema and cotton pellet-induced granuloma formation in rats. The methanol extract and the n-hexane fraction (p.o.) showed the antiinflammatory effect and analgesic effect, but the water fraction did not. These results suggested that the antiinflammatory and analgesic activity induced by the methanol extract shifted to the n-hexane fraction and the active principles may be lipophilic compounds.

Acetic Acid↗

PubMed1997

In vitro and clinical studies of image acquisition in breath-hold MR cholangiopancreatography: single-shot projection technique versus multislice technique.

OBJECTIVE: This study was undertaken to compare the in vitro and clinical value of two-dimensional multislice breath-hold MR cholangiopancreatography (MRCP) with a single-shot projection technique using a half-Fourier acquisition single-shot turbo spin-echo sequence. SUBJECTS AND METHODS: We examined 108 patients with pancreaticobiliary diseases, using breath-hold MRCP and a half-Fourier acquisition single-shot turbo spin-echo sequence on a 1.5-T MR unit with a body phased-array coil. Two data acquisition techniques were employed: multislice acquisition postprocessed by maximum intensity projection (MIP) (multislice technique) and single-shot projection with a thick slice (projection technique). In the multislice technique, nine contiguous slices were obtained with a thickness of 5 mm (acquisition time. 18 sec). In the projection technique, a single slice was obtained with a thickness of 30, 50, or 70 mm (acquisition time. 2 sec). Contrast-to-noise ratio (CNR) between the common bile duct and the liver as well as detectability of normal structures and diseases were compared for these two acquisition techniques. In the multislice technique, source images were also evaluated. ERCP or percutaneous transhepatic cholangiography images were used as the gold standard. RESULTS: Most of the pancreatic duct and common bile duct was revealed on 54% and 100% of the projection images, respectively, and on 35% and 98% of the MIP images, respectively, CNR was significantly higher with the multislice technique than with the projection technique (p < .01). With the projection technique, CNR decreased as slice thickness increased. Dilatation and occlusion of the pancreaticobiliary tree were equally well revealed by the two imaging techniques. However, abnormalities in the periampullary region and anomalies in the pancreaticobiliary tree were more clearly seen on projection images than on MIP images (p < .05). Stones in the common bile duct, gallbladder, or intrahepatic bile duct were best seen on source images acquired by the multislice technique (83% sensitivity). CONCLUSION: Because of the absence of misregistration and the speed of image acquisition, breath-hold single-shot MRCP using the projection technique with a slice thickness of 30 or 50 mm consistently revealed the pancreaticobiliary tree and periampullary region with an acceptable CNR. Stones in the bile duct were best seen on the source images acquired by the MIP technique.

Biliary Tract Diseases↗

PubMed1997

Binding conformers searching method for ligands according to the structures of their receptors and its application to thrombin inhibitors.

AIM: To develop a method of finding binding conformers for ligands according to the three-dimensional structures of their receptors. METHODS: Combining the systematic search method of ligand with the molecular docking approach of ligand fitting into its receptor, we developed a binding conformer searching method for ligands. RESULTS: The binding conformers of phosphonopeptidyl thrombin inhibitors were recognized. The binding (interaction) energies between these inhibitors and thrombin were calculated with molecular mechanical method. CONCLUSION: Both of the total binding energies and steric binding energies have good correlations with the inhibitory activities of these thrombin inhibitors, demonstrating that our approach is reasonable. It can also be used to explain the inhibition mechanism of thrombin interacting with these inhibitors.

Binding Sites↗

PubMed1997

Isolation and characterization of a new chromosome 8q24.1 band-specific microsatellite polymorphism.

A clone, containing a 24-dinucleotide (CA)-repeat sequence, was isolated from chromosome 8q24.1 band-specific pUC19 library. It was localized to target chromosome using human-rodent hybrid cell panel. Eleven alleles were estimated from 56 unrelated individuals and the heterozygosity reaches 0.835. Linkage analysis of 11 Chinese pedigrees showed significant evidence for linkage of this new marker to three dinucleotide repeat markers at 8q23-24.1 region, with the most likely position of the marker between D8S85 and D8S199.

Alleles↗

PubMed1997

[Rapid bioluminescence method for pathogen detection of nephropyelitis patient].

ATP is a kind of necessary metabolites in the living cells. We detected ATP contents in 222 bacteriuria or the urine germ by bioluminescence method. The results showed that the patient had been infected when the mean value was > 130.9 +/- 11.38 and had not when the mean value was < 32.9 +/- 2.26. The results were the same with the Gram Stain, L-form bacteriuria culture and the common bacteriuria culture. The mean values of positive specimens are higher than that of the negative specimens by the bioluminescence. Thus, it is indicated that the bioluminescence method has high sensitivity. This method can be used to detect L-form bacteriuria in the urine germ quickly and is important for early diagnosis by the doctors.

Adenosine Triphosphate↗

PubMed1997

[Synovial sarcoma in the head and neck with 3 case reports].

Synovial sarcoma in the head and neck with 3 cases are reported. Some clinical features and experiences of surgical excision are analysed according to our materials and review of the literature. We believe that the key to prevent synovial sarcoma from recurrence and matastasis is to avoid local excision, and pay more attention to this disease before operation. It is not sensitive to radiation therapy.

Adult↗

PubMed1997

[A 20-year experience in surgical management of acute necrotizing pancreatitis].

From 1974 to 1994, 243 patients with acute necrotizing pancreatitis (ANP) proved by operation or CT scanning system were treated. The overall survival rate was 70.4%. In 1974-1987, the resection of necrosis was radical and as early as possible, and the main type of operation was subtotal pancreatectomy. The survival rate in this period was 61.3% (49/80). In 1988-1991, the treatment was changed into "individualization" i.e. for sterile pancreatic necrosis, conservative treatment was setected while infected pancreatic necrosis, necrosectomy was performed early. In this period, the survival rate of conservative treatment was 85.7% (6/7) and that of operative treatment 67.1%. The overall survival rate in was 68.5% (63/92). In 1991-1994, we insisted on late operation for the patients with necrosis and comprehensive management for all the patients with ANP. The survival rate of conservative treatment in this period was 100% (11/11) and that of operative treatment 80% (48/60). The overall survival rate was 83.1% (59/71). We conclude that comprehensive management combined with late operation for the patients with necrosis infected is a better strategy for the treatment of ANP.

Adolescent↗

PubMed1997

[Clinical analysis of 153 pancreaticoduodenectomies].

153 pancreaticoduodenectomies performed from 1976 to 1995 were analyzed. The morbidity was 41.2% and the mortality 5.2%. Delayed gastric emptying (DGE) was the most common complication, and severe complications included introabdominal abscess, upper GI bleeding, and pancreatic fistula. The mortality decreased significantly from 15.6% before 1990 to 0.9% after 1990 and the morbidity decreased from 44.4% to 31.9%, and delayed gastric emptying was the major cause of mobidity after 1990 in pylorus preserving procedures.

Adolescent↗

PubMed1997

[Plasma levels of calcitonin gene-related peptide before and after percutaneous balloon mitral valvuloplasty].

The level of plasma calcitonin gene-related peptide (CGRP) in 30 patients with mitral stenosis (MS) was measured before and after percutaneous balloon mitral valvuloplasty (PBMV). The results showed that CGRP level in MS patients was significantly lower than that in controls (P < 0.001) and increased after PBMV (P < 0.001); There was significant positive or negative correlation between CGRP level and cardiac index (P < 0.01) or ET level, mean pulmonary artery pressure, mean right and left atrial pressure (P < 0.001 respectively). It is suggested that CGRP may play an important role in the pathophysiological process of MS, and the level of CGRP before and after PBMV may be a good parameter for evaluating the severity of MS and effect of PBMV.

Adult↗

PubMed1997

[The primarily study on the correlation between the cephalometric characteristics and the results of ploysomnography].

A study on correlation between temporomandibular joint ankylosis and Obstructive Sleep Apnea Syndrome (OSAS) was conducted. The statistic results demonstrate that there is significant correlation between (TA + SPA)/OPA and AI, and there is negative correlation between PAS and AI, (TA + SPA)/OPA and SaO2min by correlation and step regression between the cephalometric analysis and polysomnogram of fourteen cases of OSAS patients.

Adolescent↗

PubMed1997

[Discussion on application of traditional Chinese analgesic medicine].

When using traditional chinese analgesic medicines for aching-syndromes, it is advisable to choose herbal analgesics on the basis of diseases degree of seriousness of the root causes and symptoms, by the principle of treating both the root causes and symptoms, or treating symptoms under urgency. It is also advisable to put emphasis on mediating qi (vital energy) and blood, select herbal drugs according to different positions of pain and make use of compatibility to enlarge the working scope of traditional chinese analgesic medicines.

Analgesics, Non-Narcotic↗

PubMed1997

[Vertical transmission of hepatitis C virus].

To study the transmission of hepatitis C virus (HCV) from infected mother to their infants, out of 1047 mothers studied, 8 were anti-HCV antibody and 6 were HCV RNA positive as well as 2 mothers who were anti-HCV antibody and HCV RNA positive. 12 mothers and their 12 babies were followed up for 12 months. Only one of 12 infants showed persistently positive for anti-HCV antibody and HCV RNA at 1, 6 and 12 months of age. His HCV type was identical to his mother. These results suggest that vertical transmission is present but not an important route for HCV infection.

Adult↗