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Biomedical subjects

G Yu

Publications and source records attributed to G Yu.

At least 37 records · Page 2Linked to original sources
PubMed2001

Fgl2 prothrombinase expression in mouse trophoblast and decidua triggers abortion but may be countered by OX-2.

Spontaneous abortion of normal karyotype embryos in mice and in humans is associated with an increase in uterine T helper (Th) 1 type proinflammatory cytokines, tumour necrosis factor (TNF)-alpha, interferon-gamma and interleukin (IL)-1, and a deficiency of Th2/3 type cytokines, IL-4, IL-10, and transforming growth factor (TGF)-beta2. In mice, Th1 cytokines up-regulate a novel prothrombinase, fgl2, which via thrombin, leads to activation of polymorphonuclear leukocytes that terminate the pregnancy. Here we show that Th1 cytokines up-regulate fgl2 mRNA in fetal trophoblast and secondary decidua of CBA/JxDBA/2 and CBA/JxBALB/c matings, and promote fibrin deposition. This pattern is accompanied by a high rate of abortion. However, the spontaneous abortion rates in abortion-prone CBAxDBA/2 matings and in low abortion rate CBAxBALB/c matings were significantly lower than that expected from the frequency of implantations with high levels of fibrin and fgl2 mRNA(hi). As the glycoprotein OX-2 occurs in the pregnant rat uterus and can deviate cytokine responses to Th2/3, we investigated OX-2 in pregnant CBA/J mice. We found OX-2 mRNA was present at the same sites as fgl2 mRNA, but was reduced in response to Th1 cytokines. Furthermore, anti-OX-2 raised the abortion rate to predicted levels, while recombinant OX-2 dramatically reduced the abortion rate. Fgl2 prothrombinase may provide a mechanism explaining pregnancy loss, and conversely, successful pregnancy may be due in part to OX-2-dependent activation of maternal tolerance mechanisms at the feto-maternal interface.

Abortion, Spontaneous↗
PubMed2001

Natural history of brainstem cavernous malformations.

OBJECTIVE: To review the natural history and determine the rates of intra- and extralesional hemorrhaging of brainstem cavernous malformations (cavernomas) monitored by one neuro-ophthalmology service. METHODS: A record review of all patients with brainstem cavernomas who were evaluated by a neuroophthalmology service between 1987 and 1999 was performed. We recorded the clinical symptoms and Rankin disability grade at presentation, during the worst clinical episode, and at the last follow-up examination. Magnetic resonance imaging scans were reviewed for evidence of intralesional hemorrhage (a bleeding episode), edema, or venous anomalies, and the cavernoma size was assessed. RESULTS: Thirty-seven patients (age range, 6-73 yr; mean age at presentation, 37.5 yr) underwent a mean of 4.9 years of follow-up monitoring. At presentation, there were 27 bleeding events and 8 nonhemorrhagic events; 2 patients did not exhibit symptoms. Patients who were at least 35 years of age exhibited a lower risk of bleeding episodes (odds ratio, 0.15; 95% confidence interval, 0.1-0.4). Cavernomas of at least 10 mm were associated with a higher risk of bleeding episodes (odds ratio, 3.48; 95% confidence interval, 1.3-9.4). Thirty-nine bleeding episodes occurred in 31 patients, yielding a bleeding rate of 2.46%/yr. There were eight rebleeding episodes, yielding a rebleeding rate of 5.1%/yr. Three patients experienced extralesional bleeding episodes; all of these patients experienced rebleeding. Of the 39 follow-up magnetic resonance imaging scans, the cavernoma size was unchanged in 66.7%, smaller in 18%, and larger in 15%. At the last follow-up examination, the mean Rankin grade was 1.0 for all patients, 0.6 for the 25 nonsurgically treated patients, and 1.4 for the 12 surgically treated patients. CONCLUSION: Rebleeding is not more common among patients who first present with bleeding, and it often has little effect on the neurological status of patients. Significant morbidity attributable to a brainstem cavernoma occurred in 8% of patients during follow-up monitoring of medium duration.

Adolescent↗
PubMed2001

Acute gender-specific hemodynamic and inotropic effects of 17beta-estradiol on rats.

Estrogen has cardioprotective effects. In addition to beneficial effects on lipid metabolism, estrogen affects the vascular tone and may reduce endothelial dysfunction. In the present study, we examined acute gender-specific hemodynamic and inotropic effects of 17beta-estradiol (17beta-E) versus the control situation in open-chest rats. In addition to measurements in the intact circulation, myocardial function was examined on the basis of isovolumic registration independent of peripheral vascular effects. Regarding the dose-dependent and gender-specific effects of 17beta-E, in female rats, 17beta-E (50, 100, or 200 ng/kg) increased cardiac output (CO) (26%, 43%, and 59% versus control animals) as a result of reduction in total peripheral resistance (TPR) (-13%, -18%, and -24%) without any effect on myocardial contractility (isovolumic left ventricular systolic pressure, -1%, 0%, and -6%). These vascular effects are less pronounced in male rats (for 200 ng/kg 17beta-E: CO, 34%; TPR, -14%). We investigated gender-specific effects of 200 ng/kg 17beta-E after pretreatment with the estrogen receptor (ER) antagonist ICI 182,780. ER blockade reduced the effects of estrogen in female rats (CO, 29%; TPR, -17%) and male rats (CO, 19%; TPR, -11%). Regarding the effects of 200 ng/kg 17beta-E after pretreatment with N(G)-nitro-L-arginine methyl ester, NO synthesis inhibition completely prevented the acute vascular effects of estrogen in female rats (CO, -4%; TPR, 1%). In addition, immunohistochemical staining revealed no gender-specific differences of the vascular ER distribution. 17beta-E caused an acute dose-dependent and gender-specific reduction in the afterload. ERs are involved in both genders in this vasodilative effect that is mediated by NO. This NO-mediated effect may explain in part the cardioprotective effect of estrogen.

Animals↗
PubMed2001

Three-dimensional computer modeling of the human upper respiratory tract.

Computer simulations of airflow and particle-transport phenomena within the human respiratory system have important applications to aerosol therapy (e.g., the targeted delivery of inhaled drugs) and inhalation toxicology (e.g., the risk assessment of air pollutants). A detailed description of airway morphology is necessary for these simulations to accurately reflect conditions in vivo. Therefore, a three-dimensional (3D) physiologically realistic computer model of the human upper-respiratory tract (URT) has been developed. The URT morphological model consists of the extrathoracic (ET) region (nasal, oral, pharyngeal, and laryngeal passages) and upper airways (trachea and main bronchi) of the lung. The computer representation evolved from a silicone rubber impression of a medical school teaching model of the human head and throat. A mold of this ET system was sliced into 2-mm serial sections, scanned, and digitized. Numerical grids, for use in future computational fluid dynamics (CFD) simulations, were generated for each slice using commercially available software (CFX-F3D), AEA Technology, Harwell, UK. The meshed sections were subsequently aligned and connected to be consistent with the anatomical model. Finally, a 3D curvilinear grid and a multiblock method were employed to generate the complete computational mesh defined by the cross-sections. The computer reconstruction of the trachea and main bronchi was based on data from the literature (cited herein). The final unified 3D computer model may have significant applications to aerosol medicine and inhalation toxicology, and serve as a cornerstone for computer simulations of air flow and particle-transport processes in the human respiratory system.

Bronchi↗
PubMed2001

Detection of caspase activation in situ by fluorochrome-labeled caspase inhibitors.

Apoptosis is dependent on the activation of a group of proteolytic enzymes called caspases. Caspase activation can be detected by immunoblotting using caspase-specific antibodies or by caspase activity measurement employing pro-fluorescent substrates that become fluorescent upon cleavage by the caspase. Most of these methods require the preparation of cell extracts and, therefore, are not suitable for the detection of active caspases within the living cell. Using FAM-VAD-FMK, we have developed a simple and sensitive assay for the detection of caspase activity in living cells. FAM-VAD-FMK is a carboxyfluorescein (FAM) derivative of benzyloxycarbonyl-valine-alanine-aspartic acid-fluoromethyl ketone (zVAD-FMK), which is a potent broad-spectrum inhibitor of caspases. FAM-VAD-FMK enters the cell and irreversibly binds to activated caspases. Cells containing bound FAM-VAD-FMK can be analyzed by flow cytometry, fluorescence microscopy, or a fluorescence plate reader. Using FAM-VAD-FMK, we have measured caspase activation in live non-adherent and adherent cells. We show that FAM-VAD-FMK labeled Jurkat and HeLa cells that had undergone apoptosis following treatment with camptothecin or staurosporine. Non-stimulated negative control cells were not stained. Pretreatment with the general caspase inhibitor zVAD-FMK blocked caspase-specific staining in induced Jurkat and HeLa cells. Pretreatment of staurosporine-induced Jurkat cells with FAM-VAD-FMK inhibited affinity labeling of caspase-3, -6, and -7, blocked caspase-specific cell staining, and led to the inhibition of apoptosis. In contrast, the fluorescent control inhibitor FAM-FA-FMK had no effect. Measurement of caspase activation in 96-well plates showed a 3- to 5-fold increase in FAM-fluorescence in staurosporine-treated cells compared to control cells. In summary, we show that FAM-VAD-FMK is a versatile and specific tool for detecting activated caspases in living cells.

Affinity Labels↗
PubMed2001

[The modified process for preparing natural organic polymer flocculant chitosan].

The modified process for preparing chitosan from crab or lobster shells was developed. In the decalcification stage, 10% HCl was used as soaking solution with addition of a small quantity of A as a promoter, and the mass ratio of reactants was 10% HCl:A:crab or lobster shells = 3.5:0.5:1, continuously stirring the crab or lobster shells at 30 degrees C for 3 h in place of simply soaking the crab or lobster shells at room temperature for 16-24 h in the previous process. In the deacetylation stage, 40% NaOH solution was used with addition of a small quantity of B as a promoter, and the mass ratio of reactants was 40% NaOH:B:chitin = 4:0.2:1, keeping reaction at 105 degrees C for 2 h in place of at 115 degrees C for 6 h in the previous process. By this new process, the cost of the raw materials used for preparing chitosan was cut down 49%, the preparation time was shortened by one half, and the main properties of this chitosan such as viscosity, deacetylation and molecular weight all approached or exceeded those of the Sigma' commercial chitosan (Chitosan C-3646).

Chitin↗
PubMed2001

[The effects of Polyrhachis vicina on immunoregulation in mice].

OBJECTIVE: To study the immuno-regulatory effects of Polyrhachis vicina Roger(PVR) in mice. METHOD: By determining the immune function of normal mice and immune function-depressed or enhanced mice after the administration of PVR. RESULTS: PVR (0.25 g.kg-1.d-1 x 10 d, 0.5 g.kg-1.d-1 x 10 d, 1.5 g.kg-1.d-1 x 10 d, op) had no effects on non-specific immune function (weight of immune organs) and cell immune function (delayed type hypersensitivity, DTH) in normal mice, but could improve the non-specific immune function and fluids immune function (hemolysin assay method) in immune function-depressed mice induced with hydrocortisonun (5 x 10(-2) g.kg-1.d-1 x 5 d). Both depressed DTH and enhanced DTH induced with cyclophosphamide (Cy) at the doses of 80 mg.kg-1.d-1 x 1 d and 250 g.kg-1.d-1 x 10 d ig. respectively were regulated by PVR (1.5 g.kg-1.d-1 x 10 d). CONCLUSION: PVR has immuno-regulatory activities in mice.

Adjuvants, Immunologic↗
PubMed2001

[The tensor fascia lata racket shape myocutaneous island flap].

OBJECTIVE: To provide a racket shape tensor fascia lata myocutaneous island flap according to the anatomical form and blood supply of the tensor fascia lata. METHODS: Four tensor fascia lata racket shape myocutaneous island flaps were used in four patients clinically. All 4 flaps were for repairing abdominal defect. RESULTS: Three of the four flaps survived without complication. In one of the four flaps, skin necrosis at the distal tip was noted and needed additional skin graft. CONCLUSIONS: The tensor fascia lata racket shape myocutaneous island flap is a convenient island flap. The island flap designed like racket shape has two benefits than the conventional rectangular island flap: 1. The narrow proximal part of the flap is like a extended pedicle, which makes the broad distal part of the flap can easily be transposed to the recipient site. 2. The donor defect of the narrow proximal part can be closed directly, which lessens the size of skin graft for the donor defect. The cause of skin necrosis at the distal tip of one flap is mainly due to that the length of the flap exceeds the distal end of the middle one third of the lateral thigh.

Abdomen↗
PubMed2001

[Aging changes of alpha-amylase and lysozyme in normal parotid gland].

OBJECTIVE: To investigate the aging changes, the distribution and the content of alpha-amylase, lysozyme in the normal parotid glands. METHODS: Fifty-one specimens of parotid glands with 4 different age groups were studied by immunohistochemical method. The intensity of staining of alpha-amylase, lysozyme was recorded in different age groups. RESULTS: The staining positivity rate of alpha-amylase, lysozyme had striking differences in 4 different age groups and it gradually decreased along with the age increasing. CONCLUSIONS: There are differences among seous acinus which had similar shape and staining in HE slice. The characters of aging changes of alpha-amylase, lysozyme secreted by acinar and intercalated duct cells are conformity with the results of quantitative studies in histology.

Adolescent↗
PubMed2001

[A successive study of histopathological changes in unilateral facial muscle denervation].

OBJECTIVE: To observe the histopathological changes in unilateral facial muscle denervation. METHODS: Gomori trichrome stain, acridine orange (AO) fluorescence, enzyme-histochemistry and immunohistochemistry techniques were used for studying mitochondria, nuclei acid concentration, enzymatic activity and contraction protein expression of facial muscle in different denervation period. RESULTS: Mitochondrian function, enzymatic activity and contraction protein expression of facial muscle denervation increased in the first two weeks, then declined till 6 months. Myofiber's histotype began to transform in 1 month after denervation. Type-grouping was obvious in 6 month. Regeneration myofibers were also seen at this time. CONCLUSIONS: Unilateral facial muscles become atrophy after denervation. They have proliferating tendency from 2 month to 6 month. Therefore, within 1 month after denervation measures to benefit atrophy will be more effective.

Animals↗
PubMed2001

[Applied study on computerized quantitative facial nerve functional estimating system].

OBJECTIVE: To prove the clinical applied value of quantitative facial nerve functional estimating system (QFES) by comparing the estimating results of the computerized QFES with manual QFES. METHODS: 50 volunteers with normal facial nerve function were used. Every volunteer was taken 7 photos with digital camera, which including static, and forehead wrinkle, eyebrows knit tight, eyes closed tight, nose wrinkle, smile, pout and mouth open to maximal seven expressions. The facial nerve function was estimated by computerized QFES, and the estimating results were compared with manual estimations by QFES in our study during 1991-1994. RESULTS: All estimating indices in this study were in the range of 0.70-0.90 as well as the manual estimating results. However, the stand deviation in this study showed significantly smaller than the previous study. CONCLUSIONS: QFES is an ideal quantitative facial nerve functional estimating system, after computerization the efficiency is increased and the systemic error is decreased. It will benefit to apply computerized QFES in the facial nerve function estimating fields.

Diagnosis, Computer-Assisted↗
PubMed2001

[Antimetastatic effects of arginine-aspartate on salivary adenoid cystic carcinoma in vitro].

OBJECTIVE: To test the effects of arginine-aspartate (RD) on metastasis of salivary cystic carcinoma (SACC). METHODS: Highly metastatic SACC cell line SACC-LM was used in the study. The effect of RD on tumor cell-ECM adhesion was assayed by MTT technique. The effect of RD on invasion and migration of SACC-LM were evaluated using modified boyden chamber. RESULTS: RD inhibited tumor cell fibronectin adhesion at 5 mg/L concentration, but no effects on tumor cell laminin and tumor cell type IV collagen adhesion. RD inhibited the invasion at 1, 5, 25 mg/L, and inhibited the migration only at 25 mg/L. CONCLUSIONS: The result shows that the RD has an antimetastatic effect on SACC-LM cells in vitro.

Antineoplastic Agents↗
PubMed2001

[The effect of radix pseudostellariae from 8 habitats on spleen-deficiency and immunologic function].

75% ethanol extracts of Radix Pseudostellariae could improve spleen-deficiency and immunologic function from Yixing(Jiangsu), Tuorong (Fujian), Guangde(Anhui), Zhonggou(Shandong), Linmu(Shandong), Shanghai, Langxi(Anhui) and Xuanzhou (Anhui). They could decrease spleen-deficienly ratio, increase body weight, anus temperature, thymus and spleen indexes, and prolong swimming time in 15 degrees C water and survival time under anoxic circumstances on resperpine-induced mice. They could also inhibit delayed hypersensitivity induced by prednisolone on mice. Radix Pseudostellariae from Xuanzhou was most effective on spleen-deficiency mice.

Animals↗
PubMed2000

Heparinase I acts on a synthetic heparin pentasaccharide corresponding to the antithrombin III binding site.

A synthetic pentasaccharide, containing an intact antithrombin III (ATIII) binding site that is in clinical studies a specific antifactor Xa agent, serves as a substrate for a heparin lyase (heparinase I, EC 4.2.2.7) from Flavobacterium heparinum. Heparinase I, currently being assessed as a heparin reversal agent, also reverses the antifactor Xa activity of this synthetic pentasaccharide by breaking it down to inactive disaccharide and trisaccharide products.

Antithrombin III↗
PubMed2000

Arabidopsis transcription factors: genome-wide comparative analysis among eukaryotes.

The completion of the Arabidopsis thaliana genome sequence allows a comparative analysis of transcriptional regulators across the three eukaryotic kingdoms. Arabidopsis dedicates over 5% of its genome to code for more than 1500 transcription factors, about 45% of which are from families specific to plants. Arabidopsis transcription factors that belong to families common to all eukaryotes do not share significant similarity with those of the other kingdoms beyond the conserved DNA binding domains, many of which have been arranged in combinations specific to each lineage. The genome-wide comparison reveals the evolutionary generation of diversity in the regulation of transcription.

Amino Acid Motifs↗
PubMed2000

Sequence and analysis of chromosome 1 of the plant Arabidopsis thaliana.

The genome of the flowering plant Arabidopsis thaliana has five chromosomes. Here we report the sequence of the largest, chromosome 1, in two contigs of around 14.2 and 14.6 megabases. The contigs extend from the telomeres to the centromeric borders, regions rich in transposons, retrotransposons and repetitive elements such as the 180-base-pair repeat. The chromosome represents 25% of the genome and contains about 6,850 open reading frames, 236 transfer RNAs (tRNAs) and 12 small nuclear RNAs. There are two clusters of tRNA genes at different places on the chromosome. One consists of 27 tRNA(Pro) genes and the other contains 27 tandem repeats of tRNA(Tyr)-tRNA(Tyr)-tRNA(Ser) genes. Chromosome 1 contains about 300 gene families with clustered duplications. There are also many repeat elements, representing 8% of the sequence.

Arabidopsis↗
PubMed2000

Carboxyl-terminal fragments of Alzheimer beta-amyloid precursor protein accumulate in restricted and unpredicted intracellular compartments in presenilin 1-deficient cells.

Absence of functional presenilin 1 (PS1) protein leads to loss of gamma-secretase cleavage of the amyloid precursor protein (betaAPP), resulting in a dramatic reduction in amyloid beta peptide (Abeta) production and accumulation of alpha- or beta-secretase-cleaved COOH-terminal fragments of betaAPP (alpha- or beta-CTFs). The major COOH-terminal fragment (CTF) in brain was identified as betaAPP-CTF-(11-98), which is consistent with the observation that cultured neurons generate primarily Abeta-(11-40). In PS1(-/-) murine neurons and fibroblasts expressing the loss-of-function PS1(D385A) mutant, CTFs accumulated in the endoplasmic reticulum, Golgi, and lysosomes, but not late endosomes. There were some subtle differences in the subcellular distribution of CTFs in PS1(-/-) neurons as compared with PS1(D385A) mutant fibroblasts. However, there was no obvious redistribution of full-length betaAPP or of markers of other organelles in either mutant. Blockade of endoplasmic reticulum-to-Golgi trafficking indicated that in PS1(-/-) neurons (as in normal cells) trafficking of betaAPP to the Golgi compartment is necessary before alpha- and beta-secretase cleavages occur. Thus, although we cannot exclude a specific role for PS1 in trafficking of CTFs, these data argue against a major role in general protein trafficking. These results are more compatible with a role for PS1 either as the actual gamma-secretase catalytic activity or in other functions indirectly related to gamma-secretase catalysis (e.g. an activator of gamma-secretase, a substrate adaptor for gamma-secretase, or delivery of gamma-secretase to betaAPP-containing compartments).

Alzheimer Disease↗