Biomedical subjects

W Liu

Publications and source records attributed to W Liu.

At least 451 records · Page 25Linked to original sources

PubMed1999

c-myc and chromosome 8 centromere studies of ovarian cancer by interphase FISH.

Forty tumor specimens from patients with ovarian cancer were studied for amplification of the c-myc oncogene relative to chromosome 8 centromere number using dual-color FISH. Interphase cytogenetic analysis showed amplification of the c-myc oncogene in 40% (16/40) of tumors using the standard oncogene:centromere ratio method of analysis. Eleven of these showed moderate amplification of c-myc, and 5 samples showed high amplification. Eight of the sixteen (50%) amplified tumors were polysomic centromere 8 as were 14 of the 24 (58%) non-amplified tumors. In previously reported work with these samples, the oncogene HER-2/neu, the chromosome 17 centromere, and the tumor suppressor gene p53 had been studied. When using the standard oncogene:centromere ratio criteria, 5 samples had amplification of both the c-myc and the HER-2/neu oncogenes, 5 samples had HER-2/neu amplification but not c-myc, 11 samples had c-myc amplification but not HER-2/neu, and 19 samples had neither oncogene amplified. The p53 gene was found to be deleted in 22.5% (9/40) of samples. The loss of the p53 gene did not appear to have any clinical correlation. The presence of an extra centromere 8 also did not appear to have any clinical correlation. The Kaplan-Meier survival curve for those patients who have c-myc amplification, while not statistically significant, appears to show a trend toward poorer survival. The survival curve for patients whose tumors have HER-2/neu amplification shows no clinical significance. It is of great interest, however, that the Kaplan-Meier plot of survival for patients whose tumors have amplification of both c-myc and HER-2/neu shows a significant difference (P = 0.047). The median survival times of the doubly amplified patient group and the non-doubly amplified groups were 12 and 43 months, respectively. This is the first study of the oncogene c-myc using FISH. The results suggest that the amplification of c-myc may indicate a poorer patient survival and that the amplification of both c-myc and HER-2/neu in combination may be a better prognostic indicator of poor patient survival.

Adult↗

PubMed1999

High-temperature pulsed-field-gradient multidimensional NMR of polymers.

The application of pulsed-field-gradient (PFG) techniques has been particularly important in providing the ability to detect 2D and 3D NMR cross peaks from minor structural components in synthetic organic polymers. The lack of mobility in a large percentage of polymers leads to rapid T2 relaxation which prevents the use of pulse sequences, such as the HMBC experiment, that operate based on coherence transfer via small, long-range J couplings. High-temperature NMR increases molecular motion with corresponding line narrowing (e.g., polyethylenes are typically analyzed at 120 degrees C). However, until now, the requirement for high temperature has precluded the use of PFG methods. Here we present data from a new probe which is capable of performing high-temperature PFG coherence selection experiments at temperatures typical of those used in many polymer analyses. We illustrate the performance of this probe with PFG-HMBC spectra of a copolymer from ethylene/1-hexene/1-butene at 120 degrees C.

Magnetic Resonance Spectroscopy↗

PubMed1999

Gold-ATP.

The synthesis, purification, and chemical analysis of two covalent conjugates between ATP and undecagold are described, one in which gold is attached to the ribose moiety of ATP and the other in which it is attached to the N-6 position of the adenine base. The former probe was then used to bind to two ATP binding proteins, the helicase DnaB and the chaperone DnaK. After purification from unbound gold by column chromatography, binding was measured by UV-Vis spectroscopy, then the protein and gold were visualized by scanning transmission electron microscopy. Binding was observed with the conjugates, and virtually no binding occurred in the control of undecagold without the ATP attached. This new probe may be useful for studying nucleotide binding sites on proteins or for labeling nucleic acids or oligonucleotides directly.

Adenosine Triphosphate↗

PubMed1999

Ni-NTA-gold clusters target His-tagged proteins.

Addition of six histidines to recombinant proteins has proved useful in their purification by nickel-affinity columns. This technology was adapted by synthesizing the chelator for nickel (nitrilotriacetic acid, NTA) onto the surface of gold clusters. These Ni-NTA-gold clusters were shown to specifically target the 6His region of tagged proteins. Results were verified by column chromatography, dot and overlay blots, UV-Vis spectroscopy, and scanning transmission electron microscopy. A 6His-tagged adenovirus "knob" protein was also shown to maintain receptor binding activity after gold labeling. Two types of gold clusters were used: 1.4-nm Nanogold and a new 1.8-nm "PeptideGold" coated with an NTA-dipeptide-thiol. These novel labels should be useful in site-specific high-resolution EM labeling, as well as in metallographic development, detection in the light microscope, or direct visualization.

Adenoviridae↗

PubMed1999

Giant platinum clusters: 2-nm covalent metal cluster labels.

A new class of covalently linkable platinum cluster reagents with core diameters close to 2 nm has been prepared. The new label offers the performance advantages and versatility of the 1.4-nm Nanogold in a larger label which is more clearly visualized against electron-dense regions of a specimen. Large platinum clusters were prepared by the reduction of platinum(II) acetate in the presence of 1,10-phenanthroline ligands which had been synthetically modified to include solubilizing and reactive cross-linkable functional groups. These were then conjugated site-specifically to antibody IgG molecules and to Fab' fragments and visualized by scanning transmission electron microscopy. The resulting conjugates may be autometallographically enhanced and show sensitivity similar to that of Nanogold conjugates in immunoblotting experiments. In preliminary experiments, they have also exhibited labeling of tissue antigens and penetrate to access nuclear targets.

Affinity Labels↗

PubMed1999

Effect of ligustrazine on expression of adherent molecule CD49d and cyclin D2 in hematopoietic cells in acute radiation injured mice.

After irradiation by 8.0 Gy gamma-ray, each mouse was stomach-fed by 4 mg ligustrazine injection twice a day. On the 7th day after irradiation, CD49d expression in ligustrazine-treated group was significantly higher than that in control group (P < 0.01), and showed no difference from that in normal group (P > 0.05). On the 14th day after irradiation. CD49d expression was increased in control group, but decreased significantly in ligustrazine-treated group (P < 0.01). The expression of Cyclin D2 in spleen mononuclear cells (MNC) in ligustrazine-treated group was significantly higher than that in control group, but the ratio of G0 + G1 phase cells was significantly lower in ligustrazine-treated group (P < 0.01). This finding indicated that ligustrazine could increase the expression of adherent molecule on bone marrow hematopoietic cells and Cyclin D2 in spleen MNC, thereby promoting the growth of hematopoietic cells.

Animals↗

PubMed1999

Expression of adherent molecule and cyclin by ligustrazine in bone marrow of mice with immune-induced aplastic anemia.

Mice with immune-induced aplastic anemia (AA) were given 5 mg ligustrazine intraperitoneally twice a day. On the 14th day, the expression of CD49d, CD49c, cyclinD2 in bone marrow mononuclear cells (MNC) was examined by flow cytometry, and VCAM-1 on stromal cells was immunohistochemically measured by Strept Avidin-Biotin Complex (SABC). The expression of CD49d, CD49c, VCAM-1 and cyclinD2 in ligustrazine-treated group was significantly higher than that in AA group (P < 0.01), but the ratio of G0 + G1 phase cells was significantly lower than that in AA group (P < 0.01). The results showed that ligustrazine could improve the expression of adherent molecule and cyclin D2 in the bone marrow of mice with immune-induced aplastic anemia, thereby promoting the growth of hematopoietic cells.

Anemia, Aplastic↗

PubMed1999

Study on IL-4, IL-5 and IL-10 in liver and bone marrow of mice infected with Schistosomiasis Japonica.

To compare Th2 cytokines levels in livers and bone marrow of mice infected with Schistosomiasis Japonica and understand their implication, ABC immunohistochemical staining technique and multimedia pathologic pictures analysis were used to detect the IL-4, IL-5 and IL-10 derived from livers and bone marrow of infected mice. Results showed that in the livers of infected mice, IL-4, IL-5 and IL-10 were obviously increased over time. The level of IL-4 was increased most among the 3 indicators. In bone marrow of infected mice, however, even though IL-4 was slowly increased over time, it was lower than that of livers in 10th and 12th week. The level of IL-5 was higher than that of livers during 12th weeks. Before 10th weeks IL-10 was elevated. After 12th week IL-10 was decreased and obviously lower than that of livers. It is concluded that in mice infected with Schistosomiasis Japonica, the immune response occurred mainly in the liver. Therefore, in bone marrow, IL-5 showed obvious auto-secretion. It might be related to its biological ability to induce B cell division and eosinophil differentiation.

Animals↗

PubMed1999

Markedly elevated levels of vascular endothelial growth factor in malignant ascites.

BACKGROUND: Vascular endothelial growth factor (VEGF) is a potent angiogenic factor that also has the ability to increase vascular permeability. Malignant ascites has significant morbidity, but the mechanism of its development is unknown. Because of the permeability-inducing properties of VEGF, we hypothesized that malignant ascites formation is associated with high levels of VEGF. The purpose of our study was to determine the role of VEGF in malignant ascites formation. METHODS: Ascites from 25 patients with gastric (n = 6), colon (n = 7), or ovarian (n = 12) cancers was collected by paracentesis or surgery. VEGF protein levels were determined by enzyme-linked immunosorbent assay. The effect of ascites on endothelial cell permeability was assessed by evaluating propidium iodide uptake by human umbilical vein endothelial cells (HUVECs) exposed to ascites. Neutralizing antibodies to VEGF added to ascites were used to determine the causal effect of VEGF in permeability induction. RESULTS: VEGF protein levels were markedly increased in malignant ascites compared with levels in nonmalignant cirrhotic ascites (controls). VEGF protein levels in ovarian, gastric, and colon cancer ascites were found to be increased 45, 23, and 12 times, respectively, compared with levels in cirrhotic ascites. Malignant ascites from patients with colon and gastric cancer caused an increase in permeability in HUVECs in all cases. Neutralizing VEGF activity in colon cancer ascites decreased in-vitro HUVEC permeability in three of four cases. CONCLUSIONS: VEGF protein levels are markedly elevated in malignant ascites. VEGF may play a role in malignant ascites formation by increasing endothelial cell permeability.

Angiogenesis Inducing Agents↗

PubMed1999

Evidence that the trans-10,cis-12 isomer of conjugated linoleic acid induces body composition changes in mice.

We investigated the effects of conjugated linoleic acid (CLA) preparations, which were enriched for the cis-9,trans-11 CLA isomer or the trans-10,cis-12 CLA isomer, on body composition in mice. Body composition changes (reduced body fat, enhanced body water, enhanced body protein, and enhanced body ash) were associated with feeding the trans-10,cis-12 CLA isomer. In cultured 3T3-L1 adipocytes, the trans-10,cis-12 isomer reduced lipoprotein lipase activity, intracellular triacylglycerol and glycerol, and enhanced glycerol release into the medium. By contrast, the cis-9,trans-11 and trans-9,trans-11 CLA isomers did not affect these biochemical activities. We conclude that CLA-associated body composition change results from feeding the trans-10,cis-12 isomer.

3T3 Cells↗

PubMed1999

Changes in body composition in mice during feeding and withdrawal of conjugated linoleic acid.

Two experiments were conducted. In Experiment 1, 8-wk-old mice were fed control diet or diet supplemented with 0.5% conjugated linoleic acid (CLA) to study the effect of CLA on body composition (CLA: 40.8-41.1% c-9,t-11 isomer, 43.5-44.9% t-10,c-12 isomer). The data for CLA-fed mice vs. controls described parallel but significantly distinct responses for both absolute and relative changes in body fat mass (reduced in CLA-fed mice) and for relative changes in whole body protein and whole body water (both of which were increased in CLA-fed mice). In the CLA-fed mice, the effect on whole body protein appeared to precede the reduction in body fat mass. In Experiment 2, weanling mice were fed control diet or diet supplemented with 0.5% CLA for 4 wk (test group), at which time all mice were fed control diet devoid of added CLA. The test group exhibited significantly reduced body fat and significantly enhanced whole body water relative to controls at the time of diet change. Time trends for changes in relative body composition were described by parallel lines where the test group exhibited significantly less body fat but significantly more whole body protein, whole body water, and whole body ash than controls. Tissue CLA levels declined following the withdrawal of CLA from the diet. In skeletal muscle of mice fed CLA-supplemented diet, the t-10,c-12 isomer was cleared significantly faster than the c-9,t-11 CLA isomer.

Adipose Tissue↗

PubMed1999

Widespread alterations of alpha-synuclein in multiple system atrophy.

Glial cytoplasmic inclusions (GCI) are the hallmark of multiple system atrophy (MSA), a rare movement disorder frequently associated with autonomic dysfunction. In this study of 21 cases of MSA, GCI were consistently immunoreactive for alpha-synuclein and double-immunostained for ubiquitin and oligodendroglial markers, but not glial fibrillary acidic protein. No statistically significant difference was found in the density of GCI in various brain regions in the two forms of MSA, striatonigral degeneration (SND) and olivopontocerebellar atrophy (OPCA). Postmortem brain samples from 9 cases of MSA were fractionated according to solubility in buffer, Triton-X 100, sodium dodecyl sulfate (SDS), and formic acid, and alpha-synuclein immunoreactivity was measured in Western blots. Total alpha-synuclein immunoreactivity was increased in MSA compared to controls, with no statistically significant difference between SND and OPCA. Most of the increase was due to alpha-synuclein in SDS fractions. In controls this fraction had little or no immunoreactivity. In 7 cases and 4 controls correlations were investigated between quantitative neuropathology and biochemical properties of alpha-synuclein. Surprisingly, the amount of SDS-soluble alpha-synuclein correlated poorly with the number of GCI in adjacent sections. Furthermore, areas with few or no GCI unexpectedly had abundant SDS-soluble alpha-synuclein. These findings provide evidence that modifications of alpha-synuclein in MSA may be more widespread than obvious histopathology. Moreover, these alterations may constitute a biochemical signature for the synucleinopathies.

Aged↗

PubMed1999

Heterogeneous distribution of the two components of delayed rectifier K+ current: a potential mechanism of the proarrhythmic effects of methanesulfonanilideclass III agents.

OBJECTIVE: To elucidate the regional difference of the K+ current blocking effects of methanesulfonanilide class III agents. METHODS: Regional differences in action potential duration (APD) and E-4031-sensitive component (IKr) as well as -insensitive component (IKs) of the delayed rectifier K+ current (IK) were investigated in enzymatically isolated myocytes from apical and basal regions of the rabbit left ventricle using the whole-cell clamp technique. RESULTS: At 1 Hz stimulation, APD was significantly longer in the apex than in the base (223.1 +/- 10.6 vs. 182.7 +/- 14.5 ms, p < 0.05); application of 1 microM E-4031 caused more significant APD prolongation in the apex than in the base (32.5 +/- 6.4% vs. 21.0 +/- 8.8%, p < 0.05), resulting in an augmentation of regional dispersion of APD. In response to a 3-s depolarization pulse to +40 mV from a holding potential of -50 mV, both IK tail and IKs tail densities were significantly smaller in apical than in basal myocytes (IK: 1.56 +/- 0.13 vs. 2.09 +/- 0.21 pA/pF, p < 0.05; IKs: 0.40 +/- 0.15 vs. 1.43 +/- 0.23, p < 0.01), whereas IKr tail density was significantly greater in the apex than in the base (1.15 +/- 0.13 vs. 0.66 +/- 0.11 pA/pF, p < 0.01). The ratio of IKs/IKr for the tail current in the apex was significantly smaller than that in the base (0.51 +/- 0.21 vs. 3.09 +/- 0.89; p < 0.05). No statistical difference was observed in the voltage dependence as well as activation and deactivation kinetics of IKr and IKs between the apex and base. Isoproterenol (1 microM) increased the time-dependent outward current of IKs by 111 +/- 8% during the 3-s depolarizing step at +40 mV and its tail current by 120 +/- 9% on repolarization to the holding potential of -50 mV, whereas it did not affect IKr. CONCLUSIONS: The regional differences in IK, in particular differences in its two components may underlie the regional disparity in APD, and that methanesulfonanilide class III antiarrhythmic agents such as E-4031 may cause a greater spatial inhomogeneity of ventricular repolarization, leading to re-entrant arrhythmias.

Action Potentials↗

PubMed1999

The effect of muscle stiffness and damping on simulated impact force peaks during running.

It has been frequently reported that vertical impact force peaks during running change only minimally when changing the midsole hardness of running shoes. However, the underlying mechanism for these experimental observations is not well understood. An athlete has various possibilities to influence external and internal forces during ground contact (e.g. landing velocity, geometrical alignment, muscle tuning, etc.). The purpose of this study was to discuss one possible strategy to influence external impact forces acting on the athlete's body during running, the strategy to change muscle activity (muscle tuning). The human body was modeled as a simplified mass-spring-damper system. The model included masses of the upper and the lower bodies with each part of the body represented by a rigid and a non-rigid wobbling mass. The influence of mechanical properties of the human body on the vertical impact force peak was examined by varying the spring constants and damping coefficients of the spring-damper units that connected the various masses. Two types of shoe soles were modeled using a non-linear force deformation model with two sets of parameters based on the force-deformation curves of pendulum impact experiments. The simulated results showed that the regulation of the mechanical coupling of rigid and wobbling masses of the human body had an influence on the magnitude of the vertical impact force, but not on its loading rate. It was possible to produce the same impact force peaks altering specific mechanical properties of the system for a soft and a hard shoe sole. This regulation can be achieved through changes of joint angles, changes in joint angular velocities and/or changes in muscle activation levels in the lower extremity. Therefore, it has been concluded that changes in muscle activity (muscle tuning) can be used as a possible strategy to affect vertical impact force peaks during running.

Elasticity↗

PubMed1999

Antithrombin prevents stress-induced gastric mucosal injury by increasing the gastric prostacyclin level in rats.

The interaction of antithrombin (AT) with cell surface glycosaminoglycans has been shown to promote the endothelial release of prostacyclin (PGI2). Because PGI2 plays an important role in gastric cytoprotection, we examined whether AT prevents water-immersion restraint stress (WIR)-induced gastric mucosal injury in rats by promoting the endothelial release of PGI2. Intravenous administration of AT (250 U/kg) prevented WIR-induced gastric mucosal injury in rats. Gastric levels of 6-keto-prostaglandin F1alpha, a stable metabolite of PGI2, were significantly increased 0.5 and 1 hour after WIR in animals administered AT compared with control animals. The effects induced by AT in animals subjected to WIR were not observed in animals that were administered DEGR-Xa, a selective inhibitor of thrombin generation, or Trp49-modified AT, which lacks affinity for heparin. In animals subjected to WIR gastric mucosal blood flow was significantly reduced with a simultaneous increase in gastric mucosal microvascular permeability. Activated neutrophils have been implicated in the WIR-induced reduction of gastric mucosal blood flow by increasing microvascular permeability. Although AT prevented the reduction of gastric mucosal blood flow and the increase in gastric mucosal microvascular permeability in animals subjected to WIR, neither DEGR-Xa nor Trp49-modified AT had any effect. Pretreatment of animals with indomethacin completely inhibited the protective effects of AT against WIR-induced gastric mucosal injury and the AT-induced increase in post-WIR gastric 6-keto-prostaglandin F1alpha levels. These results strongly suggest that AT prevents stress-induced gastric mucosal injury by increasing the gastric levels of PGI2 through the interaction of AT with cell-surface glycosaminoglycans, thus increasing gastric mucosal blood flow both by vasodilation and by inhibiting neutrophil activation.

6-Ketoprostaglandin F1 alpha↗

PubMed1999

Understanding bladder regeneration: smooth muscle ontogeny.

PURPOSE: We determined the origin of smooth muscle cells in acellular bladder matrix grafts. MATERIALS AND METHODS: A total of 15 female Sprague-Dawley rats underwent partial cystectomy and grafting with an acellular matrix derived from rat bladder. The grafts were examined 1, 2, 3 and 4 weeks after grafting by immunohistochemical studies for smooth muscle markers and by transmission electron microscopy for smooth muscle morphology. Bladder matrix and bladder epithelium recombinants were created and grafted subcutaneously and under the renal capsule in nude mice. Recombinants were examined 1, 2, 3 and 4 weeks postoperatively by immunohistochemical studies for bladder epithelium and bladder smooth muscle. RESULTS: Smooth muscle ingrowth into acellular matrix was initially seen at 2 weeks. The immunohistochemical and electron microscopic characteristics of the cells were similar to those of fetal smooth muscle 2 weeks and newborn smooth muscle 4 weeks after grafting. Matrix epithelium recombinants displayed mature bladder epithelium with 3 to 7 layers but they did not support the ingrowth of smooth muscle cells. CONCLUSIONS: Mature bladder smooth muscle cells undergo dedifferentiation, migration and redifferentiation to repopulate an acellular matrix graft. It is unlikely that adult fibroblasts from the surrounding tissue are induced by epithelium and matrix to form smooth muscle. The contractile behavior of bladder substitute materials likely reflects the properties of the host bladder.

Animals↗

PubMed1999

Management of nonfunctioning pituitary adenomas with suprasellar extensions by transsphenoidal microsurgery.

BACKGROUND: We evaluated the feasibility and therapeutic effectiveness of transsphenoidal microsurgical removal of nonfunctioning pituitary adenomas with suprasellar extensions. The diagnostic modes, surgical technique, and outcome were reviewed in 208 patients with pituitary adenomas extending beyond the sella turcica who were treated by transsphenoidal microsurgery. All patients except three presented with significantly diminished visual acuity and visual field defects. METHODS: Diagnosis was confirmed by skull X-ray plain films, CT, or MRI scanning. Operations were performed via a transsphenoidal approach under microscope. A subarachnoid catheter was preoperatively inserted in the lumbar cistern, through which saline was slowly injected during operation to increase the intracranial pressure so as to move the suprasellar tumor into the operative field to aid the removal. RESULTS: In this series, gross total removal of an adenoma in 146 cases (70.2%) and subtotal removal in 50 cases (24.0%) was achieved; partial removal was carried out in the remaining 12 cases (5.8%) of fibrous or dumbbell-shaped adenomas. There were no deaths in this group. Follow-up review (median 3.8 years) in 187 patients revealed that 97.8% of those with preoperative diminished visual acuity had postoperative improvement; 2.2% had no change, and none deteriorated significantly. Among 181 patients with preoperative visual field defects, postoperative improvement was good in 169 (93.4%), and poor in 12 (6.6%). The major complications were diabetes insipidus and cerebrospinal fluid rhinorrhea, which occurred in 13.5% and 4.8% of patients, respectively. The tumors recurred in 12 patients (6.4%) who were considered to have a macroscopically complete removal at surgery. Continuing growth of residual tumors was found in 31 (16.6%) based on visual acuity decrease, visual field defects, and CT or MRI examination. Of the recurrent and residual tumors, 4, 9, 17, and 13 cases belonged to Grades A, B, C, and D, respectively. CONCLUSIONS: Comparison with transfrontal surgery suggests that these results are as good as those of transfrontal procedures and that the incidence of serious side effects is considerably lower. We consider that the microsurgical removal of pituitary tumors by the transsphenoidal approach is safe and effective even in very large or giant adenomas, since it allows rapid and adequate decompression of the optic nerves and chiasm.

Adenoma↗

PubMed1999

Gastric prostacyclin (PGI2) prevents stress-induced gastric mucosal injury in rats primarily by inhibiting leukocyte activation.

We investigated whether, in rats, gastric prostacyclin (PGI2) prevented gastric mucosal injury that was induced by water-immersion restraint stress by inhibiting leukocyte activation. Gastric levels of 6-keto-PGF1alpha, a stable metabolite of PGI2, increased transiently 30 min after stress, followed by a decrease to below the baseline 6-8 h after stress. Gastric mucosal blood flow decreased to approximately 40% of the baseline level 8 h after stress. Myeloperoxidase activity was significantly increased 8 h after stress. Treatment with indomethacin before stress inhibited the increase in 6-keto-PGF1alpha levels and markedly reduced mucosal blood flow. It also markedly increased leukocyte accumulation and mucosal lesion formation. Iloprost, a stable PGI2 analog, inhibited the indomethacin-induced decrease in mucosal blood flow, mucosal lesion exacerbation, and increase in leukocyte accumulation. Nitrogen mustard-induced leukocytopenia inhibited the indomethacin-associated lesion exacerbation and the increase in leukocyte accumulation, but not the decreases in mucosal blood flow. These observations indicate that gastric PGI2 decreases gastric mucosal lesion formation primarily by inhibiting leukocyte accumulation.

6-Ketoprostaglandin F1 alpha↗