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Biomedical subjects

Y Cui

Publications and source records attributed to Y Cui.

At least 235 records · Page 13Linked to original sources
PubMed1997

Actions of cADP-ribose and its antagonists on contraction in guinea pig isolated ventricular myocytes. Influence of temperature.

Although it is becoming widely accepted that cADP-ribose (cADPR) can regulate calcium release from the endoplasmic reticulum in sea urchin eggs and in a variety of mammalian cell types, it remains controversial whether this substance might influence calcium release during excitation-contraction coupling in cardiac muscle. We have investigated possible actions of cADPR in intact cells isolated from guinea pig ventricle, paying particular attention to the possible influence of temperature. At 36 degrees C, myocyte contraction was influenced by cytosolic application of cADPR in a concentration-dependent manner (showing an approximately 30% increase in contraction with 5 mumol/L cADPR applied via a patch pipette in myocytes stimulated to fire action potentials at 1 Hz). Calcium transients measured with fura 2 were also increased by 5 mumol/L cADPR. Antagonists of cADPR reduced contraction at 36 degrees C (by approximately 35% with either 50 mumol/L 8-Br-cADPR or 5 mumol/L 8-amino-cADPR applied via the patch pipette). At room temperature (approximately 20 degrees C to 24 degrees C), no significant effects on contraction were detected with either cADPR or its antagonists. At 36 degrees C, treatment of the cells with a mixture of 2 mumol/L ryanodine and 1 mumol/L thapsigargin to suppress function of the sarcoplasmic reticulum stores of calcium prevented the action of 5 mumol/L cADPR applied via a patch pipette. These observations are consistent with an action of cytosolic cADPR to enhance calcium-induced calcium release from the sarcoplasmic reticulum in guinea pig ventricular myocytes at 36 degrees C. The observed influence of temperature under the conditions of our experiments is one factor that might help to account for failure to detect actions of cADPR and its analogues in some previous studies.

Adenosine Diphosphate Ribose↗
PubMed1997

Ascorbic acid-dependent activation of the osteocalcin promoter in MC3T3-E1 preosteoblasts: requirement for collagen matrix synthesis and the presence of an intact OSE2 sequence.

Osteocalcin is a hormonally regulated calcium-binding protein made almost exclusively by osteoblasts. In normal cells, osteocalcin expression requires ascorbic acid (AA), an essential cofactor for osteoblast differentiation both in vivo and in vitro. To determine the mechanism of this regulation, subclones of MC3T3-E1 preosteoblasts were transiently transfected with 1.3 kb of the mouse osteocalcin gene 2 promoter driving expression of firefly luciferase. AA stimulated luciferase activity 20-fold after 4-5 days. This response was stereospecific to L-ascorbic acid and was only detected in MC3T3-E1 subclones showing strong AA induction of the endogenous osteocalcin gene. Similar results were also obtained in MC3T3-E1 cells stably transfected with the osteocalcin promoter. A specific inhibitor of collagen synthesis, 3,4-dehydroproline, blocked AA-dependent induction of promoter activity, indicating that regulation of the osteocalcin gene requires collagen matrix synthesis. Deletion analysis of the mOG2 promoter identified an essential region for AA responsiveness between -147 and -116 bp. This region contains a single copy of the previously described osteoblast-specific element, OSE2. Deletion and mutation of OSE2 in DNA transfection assays established the requirement for this element in the AA response. Furthermore, DNA-binding assays revealed that MC3T3-E1 cells contain OSF2, the nuclear factor binding to OSE2, and that binding of OSF2 to OSE2 is up-regulated by AA treatment. Taken collectively, our results indicate that an intact OSE2 sequence is required for the induction of osteocalcin expression by AA.

Animals↗
PubMed1997

Computer-assisted, quantitative cytokine enzyme-linked immunospot analysis of human immune effector cell function.

Originally developed for detecting antibody production from B lymphocytes, the enzyme-linked immunospot (ELISPOT) assay was later modified to assess cytokine production from various immune effector cells. Although the ELISPOT assay can detect antibody or cytokine production at the single-cell level, the visual counting of spots in a 96-well plate under a microscope makes this method unsuitable for handling large sample sizes. Here, we introduce a computer-assisted image analysis system to overcome this problem. This system makes the data analysis step of the ELISPOT assay convenient, objective, sensitive and suitable for handling large sample pools. Studies requiring lymphocyte proliferation assay, cytotoxic lymphocyte assay and precursor frequency assay can be conducted through the ELISPOT assay. This is demonstrated here using examples such as mixed lymphocyte allogeneic reactions and human immunodeficiency virus antigen-specific, cell-mediated immune responses.

Antigens, CD↗
PubMed1997

Follow-up study of children with precocious puberty treated with cyproterone acetate. Ad hoc Committee for CPA.

A total of 1840 children and adolescents treated with cyproterone acetate (CPA) to block gonadal function, as a treatment for precocious puberty, short stature and other disorders, were registered to survey for the risk of developing hepatic tumors. Patients responding to follow-up numbered 1552 (85%). The cumulative dose and duration of CPA therapy for boys and girls were 110.4g and 2.6 years, and 122.9 g and 2.8 years, respectively. Among the 1552 patients, five hepatoma cases were found. Four underwent successful surgery and remain alive and well to date. Two of the 5 cases had been given more than 500g, the other 3 more than 1000 g, of CPA. Three had also been given androgens before CPA administration. Although further follow-up is necessary to monitor for the development of adenoma and hepatoma, the risk of developing these tumors among patients to whom limited doses of CPA were administered appears to be negligible.

Adenoma, Liver Cell↗
PubMed1997

[Microwave operation of angiofibroma of nasopharynx under nasal endoscope].

Two patients with angiofibroma of nasopharynx were treated with microwave operation under nasal endoscope in our hospital. This operation could reduce the amount of blood less than operations by palatine apporach and nose apporach apprentently. So the blood transplantation was avoid. Meanwhile, it lessen somatopsychic pain and ecnomical burden. Because of the clean and clear operation field under nasal endoscope, the tumor could be removed completely and correctly. Then, the possibility of relapse was reduced.

Adolescent↗
PubMed1997

[Insulin receptors in diabetes mellitus].

We described the clinical significance of the measurement of insulin receptors and the mechanism of non-insulin dependent diabetes mellitus (NIDDM). Changes in insulin receptor (IR) of red blood cells in 47 patients with NIDDM were compared with those of 28 normal controls. The levels of high and low-affinity IR in the 47 patients with NIDDM were lower than those of normal controls and were prominent in untreated new NIDDM patients. Hyperinsulinemia was not found in these patients, indicating that the low IR is a primary defect not caused by the "down regulation" mechanism. In the IDDM patients the levels of high and low-affinity IR were higher than those of the normal controls, but decreased markedly after insulin therapy, indicating that the "up regulation" is attributable to the high IR levels, other than the primary IR defect.

Adolescent↗
PubMed1997

[A deep regional impedance method measuring the blood distribution in the lung].

A new deep regional impedance method to measure the blood distribution in the lung has been developed. Using a multi-electrode system, the method simultaneously detects impedance information of chest, and back including lung and the thorax, then extracts the impedance information directly from lung with a special data processing approach in order to eliminate thorax effect on the measurement. The salt pool experiment and the preliminary application of measuring the blood distribution in the lung have been made. The results show that the method raises the relative sensitivity and the distinguishability of the blood measurement in the lung, and as a new deep regional impedance measurement method, it has a good prospects of clinical application in the future.

Adult↗
PubMed1997

[VATS in malignant pleural effusions].

Between November 1992 and October 1996, 20 patients with malignant pleural effusions were submitted to VATS under general anesthesia. The overall positive histological diagnoses were obtained through VATS (20/20). The malignant pleural mesothelioma in 8 cases and metastatic cancers in 12 cases were histopathologically confirmed. Talc pleurodesis was performed for all the cases, and 18 patients gained lasting pleurodesis and the other 2 patients did not. The failure of pleurodesis was due to that the lung could not reexpand to come into contact with the chest wall. Postoperative complications included transient fever and slight asthma in 2 cases, and the symptoms were relieved obviously after some simple therapy to symptom. In conclusion, VATS has provided a high positive diagnosis of patients with malignant pleural effusions not diagnosed by conventional methods and good results in pleurodesis, but some operating skills must be emphasized.

Adult↗
PubMed1997

Thymic carcinoma (report of 14 cases).

This paper reports of 14 cases of thymic carcinoma. Most of them with symptoms of chest pain, chest stuffy and discomfort, but without combined with extrathoracic syndromes. The tumors always were large in size and frequently invaded adjacent organs, hence with low resection rate. In this series, complete resection of tumor only 2 cases, partial resection in 7 cases, exploratory thoracotomy in 5 cases. Thymic carcinoma was an extremely malignant tumor with extensive invasion intrathoracally and early metastasis extrathoracally. The common sites of metastasis were bone, liver, lung and extrathoracic lymph nodes. Adjuvant therapy postoperatively was given to all patients. Follow-up of 1-8 years showed 10 cases death, of which 5 cases died within the first year after surgery, 3 cases within the second year. Four patients were still alive so far, in which 3 patients were within 1.5 years postoperatively. Pathological studies revealed 9 cases of squamous epithelial cell thymic carcinoma, 3 of lymphoepithelioma-like thymic carcinoma and 2 of small cell undifferentiate thymic carcinoma.

Adult↗
PubMed1997

[Surface photovoltaic spectroscopic investigation of Bacteriorhodopsin (BR)].

The surface photovoltaic spectra (SPS) of Bacteriorhodopsin-based films were systematically measured. The results show that the BR films are characterized by the specific photovoltaic effect. The SPS response of the BR films depends on the fabrication and humidity of the film. The intermediate M412 and O640 of BR are observed in the SPS of HEPES-containing BR film, indicating that HEPES has very important function to stabilize intermediate M412. The observations are explained in terms of the photocycle of BR and the mechanism of photovoltage generation.

Bacteriorhodopsins↗
PubMed1997

Activation of endothelial cell phospholipase D by migrating neutrophils.

BACKGROUND: Vascular endothelium plays a critical role in regulating the integrity of intercellular adhesive and junctional contacts in response to migrating neutrophils during the inflammatory process. Biochemical responses induced in endothelial cells by adherent, migrating neutrophils are poorly understood. This study was undertaken to explore the possibility that endothelial cell phospholipase D (PLD) is activated when neutrophils migrate through endothelial cell monolayers in response to chemotactic stimuli. METHODS: Bovine pulmonary artery endothelial cells (BPAEC) were cultured on polycarbonate filters at the base of inserts in Transwell chambers (Costar, Cambridge, MA) and subsequently labeled with 3H-myristic acid. Human neutrophil migration through BPAEC monolayers was measured in response to a chemoattractant gradient produced by leukotriene B4 (LTB4). After neutrophils were induced to migrate through endothelial monolayers in the presence of 0.1% ethanol, the filters were excised, and cellular lipids were extracted. Levels of labeled phosphatidylethanol (PEt), an index of activation of endothelial cell PLD, were measured in chromatographs of resolved phospholipids. RESULTS: When neutrophils migrated through endothelial monolayers in response to LTB4, endothelial cells accumulated significant levels of PEt, indicating activation of endothelial cell PLD. Kinetic analysis demonstrated that PEt generation closely paralleled chemotactic migration over a 2-hour time period. Direct contact of neutrophils with the endothelium failed to induce PEt formation in the absence of neutrophil chemotaxis, and LTB4 was an ineffective stimulus of endothelial cell PLD activity in the absence of migrating neutrophils. Neutrophil migration-dependent endothelial PLD activation was observed when chemotaxis was induced by an unrelated chemoattractant, serum activated by exposure to Escherichia coli. However, neutrophil migration alone could not account for activation of endothelial cell PLD, since the peptide chemoattractant f-met-leu-phe (FMLP) induced comparable migration of neutrophils through endothelial monolayers but did not induce PEt generation. CONCLUSIONS: Our study indicates that chemotactic migration of neutrophils through endothelial monolayers results in endothelial cell PLD activation. This process may amplify both target and effector cell reactivity during the inflammatory response.

Animals↗
PubMed1996

Protective immunity to HIV-1 in SCID/beige mice reconstituted with peripheral blood lymphocytes of exposed but uninfected individuals.

Immunodeficiency typically appears many years after initial HIV infection. This long, essentially asymptomatic period contributes to the transmission of HIV in human populations. In rare instances, clearance of HIV-1 infection has been observed, particularly in infants. There are also reports of individuals who have been frequently exposed to HIV-1 but remain seronegative for the virus, and it has been hypothesized that these individuals are resistant to infection by HIV-1. However, little is known about the mechanism of immune clearance or protection against HIV-1 in these high-risk individuals because it is difficult to directly demonstrate in vivo protective immunity. Although most of these high-risk individuals show an HIV-1-specific cell-mediated immune response using in vitro assays, their peripheral blood lymphocytes (PBLs) are still susceptible to HIV infection in tissue culture. To study this further in vivo, we have established a humanized SCID mouse infection model whereby T-, B-, and natural killer-cell defective SCID/beige mice that have been reconstituted with normal human PBLs can be infected with HIV-1. When the SCID/beige mice were reconstituted with PBLs from two different multiply exposed HIV-1 seronegative individuals, the mice showed resistance to infection by two strains of HIV-1 (macrophage tropic and T cell tropic), although the same PBLs were easily infected in vitro. Mice reconstituted with PBLs from non-HIV-exposed controls were readily infected. When the same reconstituted mice were depleted of human CD8 T cells, however, they became susceptible to HIV-1 infection, indicating that the in vivo protection required CD8 T cells. This provides clear experimental evidence that some multiply exposed, HIV-1-negative individuals have in vivo protective immunity that is CD8 T cell-dependent. Understanding the mechanism of such protective immunity is critical to the design and testing of effective prophylactic vaccines and immunotherapeutic regimens.

Adoptive Transfer↗
PubMed1996

Synergistic effects of Vg1 and Wnt signals in the specification of dorsal mesoderm and endoderm.

In amphibians, dorsoventral asymmetry is established by cortical rotation, a cytoplasmic rearrangement in the egg which activates a dorsal determinant on one side of the zygote. This determinant has been proposed to be either Vgl, an endodermally derived molecule that can directly induce ectoderm to form dorsal mesoderm, or a member of the Wnt family, which patterns the ectoderm such that it forms dorsal mesoderm in response to ventral inductive signals. In this study, we have investigated whether the endogenous dorsal determinant(s) functions as a direct inducer of dorsal mesoderm (Vg1-like) or whether it acts to pattern the response of ectoderm to inductive signals (Wnt-like). We report here that cortical rotation enhances both the dorsal-inductive activity of endodermal cells and the response of ectodermal cells to endogenous inductive signals and that both of these activities are required for notochord induction in ectoderm/endoderm recombinants. While ectopically expressed Xwnt-8b can substitute for the dorsalizing signals activated in either ectoderm or endoderm, and can allow notochord formation in recombinants, Vg1 alone is not sufficient to induce notochord in ectodermal explants in the absence of signals activated by cortical rotation. Coexpression of Xwnt-8b along with Vg1 restores ectodermal competence to form notochord. Finally, in endodermal explants, ectopically expressed Xwnt-8b, but not Vg1, can divert the fate of ventral endodermal cells along a dorsal pathway. Thus, while Vg1 is most likely required for induction of mesoderm in vivo, our data suggest that a maternal Wnt-like signal acts synergistically with Vg1 to specify a dorsal fate not only in the mesoderm, but also in the endoderm.

Animals↗
PubMed1996

Mof4-1 is an allele of the UPF1/IFS2 gene which affects both mRNA turnover and -1 ribosomal frameshifting efficiency.

The mof4-1 (maintenance of frame) allele in the yeast Saccharomyces cerevisiae was isolated as a chromosomal mutation that increased the efficiency of -1 ribosomal frameshifting at the L-A virus frameshift site and caused loss of M1, the satellite virus of L-A. Here, we demonstrate that strains harboring the mof4-1 allele inactivated the nonsense-mediated mRNA decay pathway. The MOF4 gene was shown to be allelic to UPF1, a gene whose product is involved in the nonsense-mediated mRNA decay pathway. Although cells harboring the mof4-1 allele of the UPF1 gene lose the M1 virus, mutations in other UPF genes involved in nonsense-mediated mRNA decay maintain the M1 virus. The mof4-1 strain is more sensitive to the aminoglycoside antibiotic paromomycin than a upf1 delta strain, and frameshifting efficiency increases in a mof4-1 strain grown in the presence of this drug. Further, the ifs1 and ifs2 alleles previously identified as mutations that enhance frameshifting were shown to be allelic to the UPF2 and UPF1 genes, respectively, and both ifs strains maintained M1. These results indicate that mof4-1 is a unique allele of the UPF1 gene and that the gene product of the mof4-1 allele affects both -1 ribosomal frameshifting and mRNA turnover.

Alleles↗
PubMed1996

PTH/PTHrP receptor is temporally regulated during osteoblast differentiation and is associated with collagen synthesis.

The temporal sequence of PTH/PTHrP receptor mRNA, binding, biologic activity, and its dependence on matrix synthesis was determined using MC3T3-E1 preosteoblast-like cells and primary rat calvarial cells in vitro. Osteoblastic cells were induced to differentiate and form mineralized nodules with the addition of ascorbic acid and beta-glycerophosphate, and samples were collected from 0-26 days of culture. DNA levels as determined by fluorometric analysis increased 12- and 17-fold during the collection period for both MC3T3-E1 and primary calvarial cells respectively. Steady state mRNA levels for the PTH/PTHrP receptor as determined by northern blot analysis, were initially low for both cell types, peaked at day 4 and 5 for MC3T3-E1 and primary calvarial cells respectively, and declined thereafter. Competition binding curves were performed during differentiation using 125I-PTHrP. The numbers of receptors per microgram DNA were greatest at days 3 and 5 for MC3T3-E1 and primary calvarial cells respectively. The biologic activity of the receptor was evaluated by stimulating the cells with 10 nM PTHrP and determining cAMP levels via a binding protein assay. The PTHrP-stimulated cAMP levels increased 5-fold to peak values at day 5 for MC3T3-E1! cells and 6-fold to peak values at day 4 for the primary calvarial cells. Ascorbic acid was required for maximal development of a PTH-dependent cAMP response since ascorbic acid-treated MC3T3-E1 cells had twice the PTH-stimulated cAMP levels as non-treated cells. When the collagen synthesis inhibitor 3,4-dehydroproline was administered to MC3T3-E1 cultures prior to differentiation, there was a subsequent diminution of the PTH/PTHrP receptor mRNA gene expression and numbers of receptors per cell; however, if administered after the initiation of matrix synthesis there was no reduction in PTH/PTHrP receptor mRNA. These findings indicate that the PTH/PTHrP receptor is associated temporally at the level of mRNA, protein, and biologic activity, with a differentiating, matrix-producing osteoblastic cell in vitro.

3T3 Cells↗
PubMed1996

Messenger functions of phosphatidic acid.

Under physiological conditions, phosphatidic acid (PA) is an anionic phospholipid with moderate biological reactivity. Some of its biological effects can be attributed to lyso-PA and diacylglycerol generated by the action of cellular hydrolases. However, it is clear that the parent compound exhibits biological activities of its own. Early studies implicated PA in the transport of Ca++ across plasma membranes as well as in the mobilization of intracellular stored calcium. Both responses may be induced as a consequence of other cellular processes activated by PA, as opposed to being directly mediated by the lipid. PA may be involved in the activation of certain functions confined to specialized groupings of cells, such as the neutrophil superoxide-generating enzyme or actin polymerization. Recent studies implicate PA as an activator of intracellular protein kinases, and a PA-dependent superfamily of kinases involved in cellular signalling has been hypothesized. Deployed on the outer surface of the plasma membrane, PA potentially provides a method of communication between cells in direct contact. This review will explore the known functions of PA as an intracellular mediator and extracellular messenger of biological activities and address ways in which these functions are potentially regulated by cellular enzymes which hydrolyse the phospholipid.

Animals↗
PubMed1996

The leucine-responsive regulatory protein (Lrp) from Escherichia coli. Stoichiometry and minimal requirements for binding to DNA.

Lrp (Leucine-responsive regulatory protein) regulates the expression of a number of operons in Escherichia coli. A recent study of DNA sequences recognized by Lrp established the consensus as a 15-bp sequence, YAGHAWATTWTDCTR (Y = C/T, H = "not G," W = A/T, D ="not C," R = A/G) (Cui, Y., Wang, Q., Stormo, G. D., and Calvo, J. M. (1995) J. Bacteriol. 177, 4872-4880). Here we report the stoichiometry of Lrp binding (an Lrp dimer binds to a single binding site) and studies that define the minimal length of DNA required for binding. A double-stranded 15 mer having a sequence that closely matches the consensus does not show measurable binding to Lrp. One or two base pairs of DNA flanking each end are not sufficient for binding, but constructs having 3-5 additional base pairs (21 mer) show relatively strong binding. Single-stranded flanking DNA also contributes to strong binding. The extent of the contribution to binding is dependent upon whether the single strand is on the left or right of the double-stranded region and whether the polarity of the single-stranded DNA is 5' to 3' or 3' to 5'.

Amino Acid Sequence↗