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Biomedical subjects

Z Yu

Publications and source records attributed to Z Yu.

At least 217 records · Page 12Linked to original sources
PubMed1997

Structural characterization of human hemoglobin crosslinked by bis(3,5-dibromosalicyl) fumarate using mass spectrometric techniques.

Diaspirin crosslinked hemoglobin (DCLHb) was analyzed by mass spectrometric-based techniques to identify the protein modifications effected by the crosslinking reaction with bis(3,5-dibromosalicyl) fumarate. DCLHb consists of two principal components. These components were isolated by size-exclusion chromatography and identified by measurement of their molecular weight using electrospray mass spectrometry and subsequent peptide mass mapping and mass spectrometric sequence analysis of their individual digests. Three major RP-HPLC fractions were observed from the major hemoglobin in DCLHb. Their MWs matched the MW of heme, intact hemoglobin beta-chain, and two hemoglobin alpha-chains crosslinked by a fumarate moiety, respectively. The minor HPLC peaks of DCLHb were also separated, and characterized by mass spectrometric methods. These minor components revealed additional details of the structural nature of covalent modification of DCLHb.

Amino Acid Sequence↗
PubMed1997

The use of transgenic mice to generate high affinity p53 specific cytolytic T cells.

P53 is an attractive target immunotherapy because it is overexpressed in up to one half of all malignancies, and its overexpression often correlates with a worsened prognosis. We wanted to determine the feasibility of targeting wild-type epitopes p53 on human tumor cells. HLA A2.1 transgenic mice were immunized with the immunodominant wild-type p53 peptide epitopes, p53(149-157) and p53(264-272), along with a pan-DR helper epitope peptide in incomplete Freund's adjuvant (IFA). Twelve days later, splenocytes were harvested and stimulated with syngeneic blast cells that had been acid-treated to remove endogenous peptide and p53 peptide-pulsed. The responding cells were subsequently restimulated weekly with acid washed, peptide-pulsed Jurkat cells transfected with HLA A2.1. Peptide specific activity was tested in a chromium release assay. The resulting cytotoxic T cells (CTL) were cloned by limiting dilution. Peptide specific CTL were generated against both p53(149-157) and p53(264-272. Only p53(149-157) specific CTL were able to recognize and lyse cells that overexpressed endogenous p53. CTL clones derived from the p53(149-157) cell line demonstrated high affinity and specificity for p53(149-157) when presented by HLA A2.1+ cells. The p53(149-157) specific CTL were tested for specificity against a variety of cultured human cell lines. The CTL clones only lysed cells that overexpressed p53 in the context of HLA A2.1 and did not lyse cells with normal p53 expression or cells that lacked HLA A2.1 expression. This study demonstrates the possibility of targeting tumors, which overexpress p53, and raises the possibility transferring the high affinity, p53 specific T cell receptors from the murine CTL to human T cells.

Animals↗
PubMed1997

Suppression of pentylenetetrazol-induced seizures by carnitine in mice.

When ddY mice were pretreated with L-carnitine (5, 10 or 20 mmol/kg), clonic as well as tonic seizures induced by pentylenetetrazol (PTZ) were dose-dependently suppressed. A time/response study (PTZ was injected 1, 5, 15 or 30 min after L-carnitine) showed that the anticonvulsive effects were apparent when the interval between L-carnitine and PTZ administration was 15-30 min. Saline containing 43% sucrose prolonged the latency to the first clonic seizure but was less effective than 20 mmol/kg L-carnitine and did not suppress clonic or tonic seizures. Alterations in brain energy metabolites caused by PTZ including increase of lactate and decrease of ATP and phosphocreatine were also suppressed by L-carnitine. L-carnitine was more potent than D-carnitine in prolonging the latency to the first clonic seizure and in decreasing the frequency of clonic as well as tonic seizures. The anticonvulsive effects of L-carnitine in PTZ-induced seizures may be unrelated to the transport of long-chain acyl CoA since they were not interfered with by D-carnitine.

Animals↗
PubMed1997

Relationship between static chemical and cyclic mechanical fatigue in a feldspathic porcelain.

OBJECTIVES: The goal of this study was to determine if static chemical and cyclic mechanical fatigue are independent, or if they interact to produce greater than additive strength loss in a feldspathic porcelain. METHODS: A blunt indentation technique was used to investigate the response of a feldspathic dental porcelain to cyclic mechanical fatigue and static chemical fatigue. All specimens were fabricated in a dry inert environment and then mechanically fatigued by cyclic loading and strength-tested in dry inert nitrogenous, ambient or wet environments. A series of experiments were performed to evaluate the effects of chemical and mechanical fatigue, and their interaction on strength loss; to determine the effects of, and interaction between, the factors of cyclic fatigue environment and strength test environment on strength; to ascertain if the type of environment during strength testing influenced specimen strength; and to distinguish between chemical damage caused by exposure to moisture alone and stress corrosion damage resulting from the strength testing environment, using a pair of two-way analysis of variance, a single one-way analysis of variance and a t-test (p < 0.05). RESULTS: These experiments indicated that both static chemical fatigue and cyclic mechanical fatigue significantly reduced specimen strength, but they did not interact to produce greater than summative effects. It was also learned that chemical fatigue was not detected on initial exposure to moisture and that it occurred to a small extent during mechanical fatigue cycling, and primarily occurred during strength testing through a stress-corrosion phenomenon. Micrographs visually evaluated the effects of mechanical and chemical fatigue on surface contact damage. SIGNIFICANCE: As both static chemical and cyclic mechanical fatigue influenced porcelain strength, they should both be considered in future evaluations. However, because they largely acted independently, they can be studied separately.

Aluminum Silicates↗
PubMed1997

Alkylation of a catalytic aspartate group of the SIV protease by an epoxide inhibitor.

Specific irreversible inhibition of the SIV protease by FMOC-protected piperidine epoxide 1 involves alkylation of the protein. Tryptic digestion of the alkylated protein and mass spectrometric analysis of the peptides identify an active site aspartic acid (Asp-25) as the single residue that is alkylated. Computer modeling of 1 bound in the crystal structure of the SIV protease using DOCK 3.5 indicates that 1 has appropriate access to the active site. It is able to align in an orientation that allows a proton to be transferred to the epoxide from one of the catalytic aspartic acid groups in conjunction with nucleophilic attack on the epoxide of the carboxylate moiety of the second catalytic aspartic acid residue. Hydrophobic interactions are not optimal for this process due, in part, to the rigidity of the inhibitor ring system and the planar conformation of the amide. The combination of modeling with protein alkylation can provide insights into structural modifications of the inhibitor that may lead to improved inhibitory activity.

Alkylation↗
PubMed1997

A low molecular weight substance purified from human placenta inhibits cAMP-dependent protein kinase and activates protein kinase C.

We have purified from human placenta a low molecular mass substance that inhibits cAMP-dependent protein kinase and activates protein kinase C. This protein kinase regulator was purified in three steps: (1) homogenizing placentas in chloroform/methanol and extracting the regulator into water; (2) eluting a strong anion exchange high performance liquid chromatography (HPLC) column with a quaternary gradient; and (3) eluting a reversed-phase HPLC column with a binary gradient. The regulator was found to be highly purified by HPLC, thin-layer chromatography (TLC) and laser desorption ionization mass spectrometry with a molecular mass of 703 Daltons by the latter procedure. The physical and biochemical properties of this protein kinase regulator suggest that it is a phospholipid but it did not co-elute by HPLC or by TLC with any of the known phospholipid activators of protein kinase C.

Biological Factors↗
PubMed1997

Association of influenza virus NP and M1 proteins with cellular cytoskeletal elements in influenza virus-infected cells.

We have investigated the association of the influenza virus matrix (M1) and nucleoprotein (NP) with the host cell cytoskeletal elements in influenza virus-infected MDCK and MDBK cells. At 6.5 h postinfection, the newly synthesized M1 was Triton X-100 (TX-100) extractable but became resistant to TX-100 extraction during the chase with a t1/2 of 20 min. NP, on the other hand, acquired TX-100 resistance immediately after synthesis. Significant fractions of both M1 and NP remained resistant to differential detergent (Triton X-114, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate [CHAPS], octylglucoside) extraction, suggesting that M1 and NP were interacting with the cytoskeletal elements. However, the high-molecular-weight form of the viral transmembrane protein hemagglutinin (HA), which had undergone complex glycosylation, also became resistant to TX-100 extraction but was sensitive to octylglucoside detergent extraction, indicating that HA, unlike M1 or NP, was interacting with TX-100-insoluble lipids and not with cytoskeletal elements. Morphological analysis with cytoskeletal disrupting agents demonstrated that M1 and NP were associated with microfilaments in virus-infected cells. However, M1, expressed alone in MDCK or HeLa cells from cloned cDNA or coexpressed with NP, did not become resistant to TX-100 extraction even after a long chase. NP, on the other hand, became TX-100 insoluble as in the virus-infected cells. M1 also did not acquire TX-100 insolubility in ts 56 (a temperature-sensitive mutant with a defect in NP protein)-infected cells at the nonpermissive temperature. Furthermore, early in the infectious cycle in WSN-infected cells, M1 acquired TX-100 resistance very slowly after a long chase and did not acquire TX-100 resistance at all when chased in the presence of cycloheximide. On the other hand, late in the infectious cycle, M1 acquired TX-100 resistance when chased in either the presence or absence of cycloheximide. Taken together, these results demonstrate that M1 and NP interact with host microfilaments in virus-infected cells and that M1 requires other viral proteins or subviral components (possibly viral ribonucleoprotein) for interaction with host cytoskeletal components. The implication of these results for viral morphogenesis is discussed.

Animals↗
PubMed1997

[Effects of hypoxia and taurine on vasoconstriction peptides from cultured bovine pulmonary arterial endothelial cells].

OBJECTIVE: To study roles of endothein-1 (ET-1), angiotensin-II (AT-II) and endogenous digitalis-like factor (EDF) from cultured bovine pulmonary arterial endothelial cells (PAEC) in the pathogenesis of hypoxic pulmonary hypertension, and to evaluate whether Taurine is capable of protecting tissue cells from injury. METHODS: Culture of bovine pulmonary arterial endothelial cells and dot blot hybridization. RESULTS: PAEC cultured under hypoxia resulted in an increase in ET-1 mRNA expression. PAEC cultured under hypoxia induced increase in ET-1, AT-II and EDF release. By adding taurine to the culture medium, ET-1 mRNA express was inhibited. ET-1, AT-II and EDF release were inhibited. CONCLUSIONS: Expression of ET-1 mRNA and release of ET-1, AT-II and EDF from PAEC increased under hypoxia. Taurine can inhibit the hypoxia-induced expression of ET-1 mRNA of PAEC and reduce the release of ET-1, AT-II and EDF from PAEC.

Angiotensin II↗
PubMed1997

[Meningo-cerebral arteriovenous malformations].

22 patients with meningo-cerebral arteriovenous malformations, we treated in our hospital between 1990 and 1995. Clinical manifestations included headache, nausea, seizure, intracranial hemorrhage, and progressive hemispheric neurologic deficits. The niduses were extensive and had dual feeding from internal and external carotid arteries. All patients underwent endovascular treatment and 4 surgical operations. The curative effect was satisfactory. The clinical and angiographic characteristics were discussed.

Adolescent↗
PubMed1997

[Hodgkin's disease with concurrent infection of toxoplasmosis].

Hodgkin's disease (HD) is a specific type of malignant lymphoma characteristic of local and general lymphadenectasis. Aquired toxoplasmosis (AT) is one kind of lymphoadenopathy without fever and fatigue. When the two diseases coexist, clinical and pathological misdiagnosis may be made. This is the first male case of toxoplasmosis and Hodgkin's disease in China, diagnosed by surgical removal of the major part of the cervical and supraclavicular masses, detection of blood anti-toxoplasma gondii antibody, PCR analysis of toxoplasma gondii DNA, and pathological, ultrastructural and immunohistochemical studies of the tumour tissues. The patient treated by radiation and chemotherapy was abated.

Adult↗
PubMed1997

[Thin split thickness skin grafting double taken from avulsed skin in treatment for skin avulsion in children].

In order to utilize avulsed skin to cover skin defects, a new skin grafting technique, thin split thickness skin grafting double taken from avulsed skin, was used in 23 cases of severe skin avulsion. The skin grafts in profound layer were observed histologically. The results showed no difference between skin grafts in superficial layer and ones in profound layer, but the latter needed longer time to heal. Using this technique, we can obtain skin graft in double amount from avulsed skin.

Adolescent↗
PubMed1997

Effects of superoxide anion, B(alpha)P and TPA on the membrane fluidity of NIH3T3 cells.

The membrane fluidity of NIH3T3 cells treated with low and high concentration of cell stimulatives (extracellular generated superoxide anion(O2-.),12-O-tetra-decanoyl-phorbol-13-acetate(TPA), and benzo(alpha)-pyrene[B(alpha)P]) was investigated by means of fluorescence labels 1,6-diphenyl-1,3,5 hexatriene (DPH) and N-(3-pyrene) maleimide (N(3p)M). The high concentration of O2-., TPA, B(alpha)P greatly increased the fluidity of cell membrane lipid domain. No changes of the florescence polarization of DPH was found in membrane lipid domain treated with low concentration of O2-., TPA, and B(alpha)P. However, decrease in the fluoresence polarization of N(3p)M on the cell membrane protein domain damaged by low concentration of cell stimulatives was observed, showing that these treatment could influence the conformation of membrane protein. The possible relationship between the changes of the conformation of membrane protein and the cell transformation and its carcinogenic machenisms were discussed.

3T3 Cells↗
PubMed1997

[Study on the relationship between intratumor microvessel density and neck metastasis of laryngeal and hypopharyngeal squamous cell carcinomas].

Sixty-one laryngeal and hypopharyngeal squamous cell, carcinoma (LC, HPC) tissue slides were immunochemically stained using LSAB method to study epithelium cells. The results demonstrated that (1) intratumor microvessel density (ITMD) in LC and HPC group was higher than that of the benign group (P < 0.05). ITMD was higher in the subgroup of LC and HPC with positive lymph node positive than that with negative lymph nodes. This result suggest that ITMD is relevant not only to the nature of the tumor, but also to lymph node metastasis. The level of ITMD is an important predictive sign of metastasis. (2) The relationship between ITMD and the clinical staging had no statistic significance (P > 0.05). (3) The analysis on the relationship between ITMD and pathologic differentiation indicated that the level of ITMD raised gradually with the lowering of the pathologic differentiation.

Carcinoma, Squamous Cell↗
PubMed1997

[Effects of yizhi pills on memory, superoxide dismutase and malondialdehyde of brain and immunity in mice].

Passive avoidance tests have shown that Yizhi Pills (YZ) markedly improve the memory of normal mice at a dose of 100 mg/kg after oral administration for fifteen days, and significantly reverse the scopolamine, NaNO2 and EtOH-induced disruptions of memory retention in mice at doses of 100, 200, 500 mg/kg after oral administration for five days. In aged mice induced by D-galactose, YZ also significantly improve the impaired memory, increase the activity of SOD and decrease the content of MDA in brain. All these effects were observed at doses of 200, 500 mg/kg after oral administration for forty-one days. YZ significantly promote blood carbon particle clearance, enhance hemolysin antibody in immunodepressed mice induced by cyclophosphamide, and increase earswelling in immunodepressed mice induced by prednisolonum.

Animals↗
PubMed1997

[Pharmacological study on the compatibility of cortex Cinnamomi with Halloysitum Rubrum].

The decoction of Cortex Cinnamomi (CC, 1 g/kg p.o.) and Halloysitum Rubrum (HR, 3 g/kg p.o.) or the combination of the two drugs (4 g/kg p.o., CC 1 g/kg, HR 3 g/kg) could antagonize the diarrhea caused by p.o. water ex tract of Radix et Rhizoma Rhei in mice; and inhibit the platelet aggregation induced by ADP in vitro. Meanwhile, the effect of the combination of the two drugs was not different from that of each single one. In addition, CC was able to inhibit the spontaneous movement of intestine in situ and showed an analgesic effect (hot-plate method) in mice; HR was ineffective in these aspects and did not reduce the effect of CC. CC(20 g/kg p.o., i.p. or i.v.) exhibited very strong toxicity in mice, while HR(60 g/kg p.o., i.p. or i.v.) was nontoxic. When the two drugs were used together, the toxicity was markedly reduced.

Aluminum Silicates↗
PubMed1997

[Adaptation of myocardial function to simulated weightlessness].

To observe the changes in myocardial function and calcium ion release of sarcoplasmic reticulum in rats under simulated weightlessness, 24 Sprague-Dawley male rats were divided into control (CON), 8 week tail-suspension (SUS) and recovery for 2 weeks (RE) groups. The results showed that there was no change in resting tension of myocardial twitch in SUS. While the developed tension (DT) of myocardial twitch significantly decreased in SUS as compared with CON. The time to peak tension (TPT) and time to half relaxation (T1/2R) of myocardial twitch were prolonged in SUS. DT, TPT and T1/2R recovered to their corresponding control values after 2 w of recovery from tail-suspension. The early recovery curve of force-interval relation in SUS was in a higher position over that of CON, but the rest potentiation and rest depression curve was positioned under that of CON. These results suggested that there might be an adaptative change in myocardial function in medium- or long-term tail-suspended rats while 8 w tail-suspension reduces calcium ion release from cardiac sarcoplasmic reticulum in rats.

Adaptation, Physiological↗
PubMed1997

[Textual research on Wei Yuhuang's life].

Wei was not only a noted doctor, but also a poet, who made friends with contemporary famous scholars. Based on these scholar's writings, this author maintains that Wei's sobriquet was not "Yuhuang", but rather "Yuheng"; and his date of birth was 1719, not in 1722; He had lived a life of 54 years old, not 50. Wei was born in Guangdong, later came to Hangzhou at 12 years old. His life was full of frustrations. The article makes a textural research into his tracks, means of making a living, to his places of activities especially in Hangzhou.

China↗