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Biomedical subjects

G Ren

Publications and source records attributed to G Ren.

At least 19 recordsLinked to original sources
PubMed2006

Evaluation of cytotoxic activities of some medicinal polypore fungi from China.

The petrol ether, ethyl acetate and methanol extracts of eight medicinal polypore fungi from China were evaluated for cytotoxic activities using MTT-dye assay. All the petrol ether and ethyl acetate extracts exhibited cytotoxicity against human cervix epitheloid carcinoma cell lines (Hela) and human hepatoma cell lines (SMMC-7721). Cytotoxicity activity was also observed in the methanol extracts of Phellinus conchatus and Pycnoporus sanquineus, but the methanol extracts from Cryptoporus volvatus, Fomitopsis pinicola, Fomes hornodermus, Lenzites betulina, Trametes gibbosa and Trametes orientalis showed weak activity when compared with quercetin.

Antibiotics, Antineoplastic↗
PubMed2006

Extracellular matrix remodeling in canine and mouse myocardial infarcts.

Extracellular matrix proteins not only provide structural support, but also modulate cellular behavior by activating signaling pathways. Healing of myocardial infarcts is associated with dynamic changes in the composition of the extracellular matrix; these changes may play an important role in regulating cellular phenotype and gene expression. We examined the time course of extracellular matrix deposition in a canine and mouse model of reperfused infarction. In both models, myocardial infarction resulted in fragmentation and destruction of the cardiac extracellular matrix, extravasation of plasma proteins, such as fibrinogen and fibronectin, and formation of a fibrin-based provisional matrix providing the scaffold for the infiltration of granulation tissue cells. Lysis of the plasma-derived provisional matrix was followed by the formation of a cell-derived network of provisional matrix composed of cellular fibronectin, laminin, and hyaluronic acid and containing matricellular proteins, such as osteopontin and osteonectin/SPARC. Finally, collagen was deposited in the infarct, and the wound matured into a collagen-based scar with low cellular content. Although the canine and mouse infarcts exhibited a similar pattern of extracellular matrix deposition, deposition of the provisional matrix was more transient in the mouse infarct and was followed by earlier formation of a mature collagen-based scar after 7-14 days of reperfusion; at the same timepoint, the canine infarct was highly cellular and evolving. In addition, mature mouse infarcts showed limited collagen deposition and significant tissue loss leading to the formation of a thin scar. In contrast, dogs exhibited extensive collagen accumulation in the infarcted area. These species-specific differences in infarct wound healing should be taken into account when interpreting experimental infarction studies and when attempting to extrapolate the findings to the human pathological process.

Animals↗
PubMed2003

Proliferating cell populations in experimentally-induced hydrocephalus in developing rats.

To examine the fate of proliferating brain cells in hydrocephalus (Hydro), experimental Hydro was induced in neonatal rats by intracisternal injection of kaolin and, 3 weeks later, the rats were injected with bromodeoxyuridine (BrdU). The BrdU (+) cells were immunohistochemically analyzed by using antibodies against neural (nestin), neuronal (NeuN) and glial (GFAP and MBP) markers in the posterior cerebrum. The percentage of nestin expression for the BrdU (+) cells was 8% in control and increased from 17% in the Hydro to 33% in the Hydro at an earlier stage after the shunt procedure, but was restored to 6% in the Hydro at a later stage after the shunt procedure. The percentages of GFAP expression showed a similar tendency to those of nestin expression. The BrdU (+) cells did not express either NeuN or MBP throughout the experiments.

Animals↗
PubMed2001

Visualization of a water-selective pore by electron crystallography in vitreous ice.

The water-selective pathway through the aquaporin-1 membrane channel has been visualized by fitting an atomic model to a 3.7-A resolution three-dimensional density map. This map was determined by analyzing images and electron diffraction patterns of lipid-reconstituted two-dimensional crystals of aquaporin-1 preserved in vitrified buffer in the absence of any additive. The aqueous pathway is characterized by a size-selective pore that is approximately 4.0 +/- 0.5A in diameter, spans a length of approximately 18A, and bends by approximately 25 degrees as it traverses the bilayer. This narrow pore is connected by wide, funnel-shaped openings at the extracellular and cytoplasmic faces. The size-selective pore is outlined mostly by hydrophobic residues, resulting in a relatively inert pathway conducive to diffusion-limited water flow. The apex of the curved pore is close to the locations of the in-plane pseudo-2-fold symmetry axis that relates the N- and C-terminal halves and the conserved, functionally important N76 and N192 residues.

Amino Acid Sequence↗
PubMed2001

Glomerular complement regulation is overwhelmed in passive Heymann nephritis.

BACKGROUND: An injection of anti-Fx1A antibodies in rats leads to passive Heymann nephritis (PHN), a model of membranous nephropathy. Fx1A is a crude extract of renal cortex that contains megalin as a principal component. However, when rats are given anti-megalin antibodies, abnormal proteinuria does not occur. Because of the established complement dependence of PHN, we hypothesized that antibodies neutralizing complement regulatory proteins in the rat glomerulus also were required to induce PHN. Two likely targets are Crry and CD59, proteins abundant on the rat podocyte and contained within Fx1A that inhibit the C3 convertase and C5b-9 assembly, respectively. METHODS: Rats were injected with anti-megalin monoclonal antibodies, followed by anti-Crry and/or anti-CD59 F(ab')(2) antibodies five days later. In a second group of experiments, rats were injected with anti-Fx1A or anti-Fx1A immunodepleted of reactivity against Crry and/or CD59. RESULTS: In the setting of podocyte-associated anti-megalin monoclonal antibodies, simultaneous neutralization of Crry and CD59 function led to the development of significant proteinuria (11.0 +/- 2.1 mg/day, P < 0.001 vs. all other groups). In contrast, animals that had neither or only one of these complement regulators inhibited had normal urinary protein excretion (< or =6 mg/day). In animals given anti-Fx1A depleted of anti-Crry and/or anti-CD59, all groups developed typical PHN, characterized by heavy proteinuria and extensive glomerular deposition of C3 and C5b-9. CONCLUSION: Crry and CD59 play an important role in restraining complement-mediated injury following subepithelial immune complex deposition; however, in PHN, their regulatory capacity is overwhelmed.

Animals↗
PubMed2001

Pharmacological comparison of native mitochondrial K(ATP) channels with molecularly defined surface K(ATP) channels.

Many mammalian cells have two distinct types of ATP-sensitive potassium (K(ATP)) channels: the classic ones in the surface membrane (sK(ATP)) and others in the mitochondrial inner membrane (mitoK(ATP)). Cardiac mitoK(ATP) channels play a pivotal role in ischemic preconditioning, and thus represent interesting drug targets. Unfortunately, the molecular structure of mitoK(ATP) channels is unknown, in contrast to sK(ATP) channels, which are composed of a pore-forming subunit (Kir6.1 or Kir6.2) and a sulfonylurea receptor (SUR1, SUR2A, or SUR2B). As a means of probing the molecular makeup of mitoK(ATP) channels, we compared the pharmacology of native cardiac mitoK(ATP) channels with that of molecularly defined sK(ATP) channels expressed heterologously in human embryonic kidney 293 cells. Using mitochondrial oxidation to index mitoK(ATP) channel activity in rabbit ventricular myocytes, we found that pinacidil and diazoxide open mitoK(ATP) channels, but P-1075 does not. On the other hand, 5-hydroxydecanoic acid (5HD), but not HMR-1098, blocks mitoK(ATP) channels. Although pinacidil is a nonselective activator of expressed sK(ATP) channels, diazoxide did not open channels formed by Kir6.1/SUR2A, Kir6.2/SUR2A (known components of cardiac sK(ATP) channels) or Kir6.2/SUR2B. P-1075 activated all the K(ATP) channels, except Kir6.1/SUR1 channels. Glybenclamide potently blocked all sK(ATP) channels, but 5HD only blocked channels formed by SUR1/Kir6.1 or Kir6.2 (IC(50)s of 66 and 81 microM, respectively). This potency is similar to that for block of mitoK(ATP) channels (IC(50) = 95 microM). In addition, HMR-1098 potently blocked Kir6.2/SUR2A channels (IC(50) = 1.5 microM), but was 67 times less potent in blocking Kir6.1/SUR1 channels (IC(50) = 100 microM). Our results demonstrate that mitoK(ATP) channels closely resemble Kir6.1/SUR1 sK(ATP) channels in their pharmacological profiles.

ATP-Binding Cassette Transporters↗
PubMed2000

Three-dimensional fold of the human AQP1 water channel determined at 4 A resolution by electron crystallography of two-dimensional crystals embedded in ice.

Here, we present a three-dimensional (3D) density map of deglycosylated, human erythrocyte aquaporin 1 (AQP1) determined at 4 A resolution in plane and approximately 7 A resolution perpendicular to the bilayer. The map was calculated by analyzing images and electron diffraction patterns recorded from tilted (up to 60 degrees ), ice-embedded, frozen-hydrated 2D crystals of AQP1 in lipid bilayer membranes. This map significantly extends the findings related to the folding of the AQP1 polypeptide chain determined by us at a lower, 7 A by approximately 20 A, resolution. The solvent-accessible volume within a monomer has a vestibular architecture, with a narrow, approximately 6.5 A diameter constriction near the center of the bilayer, where the location of the water-selective channel is postulated to exist. The clearly resolved densities for the transmembrane helices display the protrusions expected for bulky side-chains. The density in the interior of the helix barrel (putative NPA box region) is better resolved compared to our previous map, suggesting clearer linkage to some of the helices, and it may harbor short stretches of alpha-helix. At the bilayer extremities, densities for some of the inter-helix hydrophilic loops are visible. Consistent with these observed inter-helix connections, possible models for the threading of the AQP1 polypeptide chain are presented. A preferred model is deduced that agrees with the putative locations of a group of aromatic residues in the amino acid sequence and in the 3D density map.

Aquaporin 1↗
PubMed2000

Polymorphism in the packing of aquaporin-1 tetramers in 2-D crystals.

Hitherto, the packing arrangement of the aquaporin-1 (AQP1) tetramer in 2-dimensional (2-D) crystals (two-sided plane group p42(1)2) was observed to be largely similar (canonical crystal form) despite the difference in the source of the protein, the glycosylation state of the protein, the type of lipids, and the ratio of lipid to protein in the crystallization mixture. We report here our observation that the packing of AQP1 tetramers shows polymorphism in 2-D crystals generated in dioleoyl phosphatidylcholine bilayers. Apart from the canonical form, three additional allomorphs were identified. One was observed when small (0.25) lipid to protein ratio was used in the crystallization mixture while the other two were observed when the divalent cation content in the canonical crystals was modified. The various allomorphs were distinguished by different relative orientations of the AQP1 tetramer viewed in projection. The same, two-sided plane group p42(1)2 and similar unit cell dimensions were maintained in the different allomorphs as established by analysis of images of frozen-hydrated, nominally untilted crystals. Our results indicate that the interaction between the AQP1 monomers at the interface of the tetramers is flexible and is also strongly influenced by Mg(2+) ions with the cation effect materializing because of the intrinsic fluidity of the membrane.

Aquaporin 1↗
PubMed2000

Drying of steamed Asian ginseng (Panax ginseng) roots by microwave-hot air combination.

Steamed Asian ginseng (Panax ginseng) roots were dried by a combined microwave-hot air method in a modified experimental microwave oven. Hot air drying was used as a reference method. The drying time to achieve the desired moisture level (10%) as well as the ginsenoside contents and the color of the final product were determined. The ginsenosides Rb1, Rb2, Rc, Rd, Re, Rf, Rg1 and Ro were analyzed by HPLC. Compared with hot air drying, the combined microwave-hot air drying method resulted in a substantial decrease (approximately 30-40%) in drying time and had little influence on the ginsenoside contents and the color of the final product.

Chromatography, High Pressure Liquid↗
PubMed2000

Predicting color kinetics during red Asian ginseng (Panax ginseng) preparation.

A red Asian ginseng preparation was prepared as follows: fresh Asian ginseng (Panax ginseng) roots were first steamed for half an hour to several hours, and then the steamed roots were dried into died roots (red Asian ginseng, 10% moisture content, on a dry basis). During steaming, the color of ginseng (white) turned yellow and brown during subsequent steaming. Color is an important index for grading red Asian ginseng. In this study, the effects of drying time and temperature on the surface color formation (L, a/b) of the Asian ginseng, and the color formation (L, a/b) of the red Asian ginseng powder were investigated. The value of L decreased, while the value of a/b increased as drying proceeded; the value of L was slightly influenced by the drying temperature, but the value of a/b was markedly influenced. With respect to the color of the final product (red ginseng), the value of L was slightly influenced by steaming time and temperature, while the value of a/b was increased as steaming time and drying temperature increased. Based on the nth-order rate equation and Arrhenius equation, a kinetic model for describing these effects was established, and the results were satisfactorily fitting.

Algorithms↗
PubMed2000

[Studies on fermentation of decane 1,10-dicarboxylic acid(DC12)].

Candida tropicalis strain UH-2-48 can increase the production of decane 1,10-dicarboxylic acid(DC12) yield by 30% (from 81.7 g/L to 108.2 g/L) after regulating the fermentation condition. The purity of the DC12 is above 97%, which can meet the criteria of the succeeding synthesized industrial productions. Emulsifier can not only destroy the structure of the cell membrane in some degree, but also can enhance the permeability of the cell membrane. Furthermore, the structure of the emulsifier itself can also effect its function. Tween 60(0.10%) can enhance the production of DC12 tremendously. Urea, as the nitrogen resource, can affect the activity of cytochrome P450 enzyme. Some biochemistry and biophysics factors, such as penicillin, vitamin B2 and alanine, can increase the yield of DC12 during the process of fermentation. Ferment in 20 m3 fermentator, under the optimal condition, the average yield of DC12 using the strain HP-12 which derived from UH-2-48, is 202.1 g/L.

Candida↗
PubMed2000

[Inhibition of monocytes adhesion to the intima of arterial wall by local expression of antisense monocyte chemotactic protein-1].

OBJECTIVE: To study the mechanism of monocyte recruitment in atherogenesis and to clarify the effect of monocyte chemotactic protein-1 (MCP-1) in this process. METHODS: Femoral arteries isolated from the rabbits which had been fed with a high cholesterol diet and locally perfused with MM-LDL within the artery beforehand, were used as the models. Antisense MCP-1cDNA was transferred into the arterial wall by injecting recombinant LNCX-anti-MCP-1/liposomal complex in the femoral sheath and the periarterial tissue. RESULTS: Expression of antisense MCP-1 mediated by recombinant LNCX plasmid/lipsomal complex gene transfer enabled to inhibit MCP-1 gene expression and adhesion of monocyte to the intima. CONCLUSION: MCP-1 plays an important role on the recruitment of monocytes in the arterial wall, which provides a potential clue in developing a gene therapy project for the prevention and treatment of atherogenesis.

Animals↗
PubMed2000

[Effect of sugars and pH on the fermentation of decane 1,10-dicarboxylic acid].

Some sugars, such as lactose, maltose, raffinose, glucose etc. can increase the purity of DC12 compared with sucrose. The value of pH can affect the process of producing DC12. Controlling the pH value between 7.5-8.0 can highly improve the production of DC12. Candida tropicalis can symport the DC12 with H+ to the outside of the cell.

Candida tropicalis↗
PubMed2000

[Surgery for tumors of the root of neck].

OBJECTIVE: To investigate the clinical value of the surgery for tumors located in the root of the neck. METHODS: A retrospective study was made on 15 cases with tumors in the root of the neck. Seven patients had benign and 8 had malignant tumors. In the malignant group, 4 staged III and 4 staged IV. Patients with benign disease were followed up for more than 3 years, and patients with malignant tumors were followed up from 1 to 5 years (median 2 years). RESULTS: Resection via "L" incision in the root of the neck was employed in 13 cases (7 benign and 6 malignant, clavicle splitting in 1 case) and sternotomy in 2 cases. Only one case in the benign group had complication (chylous leakage). In contrast, 7 complications (2 subclavian vein tearing, 2 brachial plexus injury, 2 chylous leakage and 1 pneumothorax) occurred in 6 patients in the malignant group. The incidence of complication was significantly different between the two groups (P < 0.05). We observed no recurrence in both groups during the period of follow-up. CONCLUSIONS: This study showed that surgery of tumors located in the root of the neck is effective, although the incidence of surgical complication is high for the malignant ones.

Adolescent↗
PubMed1999

Degradation of ginsenosides in American ginseng (Panax quinquefolium) extracts during microwave and conventional heating.

The degradation of ginsenosides in American ginseng (Panax quinquefolium) extracts during microwave and water (oil) bath heating (conventional heating) was investigated. Both the 50% ethanol-water extracts and the aqueous extracts were boiled in a modified laboratory microwave oven and in a water (or oil) bath, respectively. The neutral ginsenosides (Rb(1), Rc, Rd, and Re) and malonyl ginsenosides (m-Rb(1), m-Rc, and m-Rd) were determined by reverse-phase high-performance liquid chromatography. The results showed that the degradation of ginsenosides in 50% ethanol-water extracts was a first-order reaction. The malonyl ginsenosides were much less stable than the corresponding neutral ginsenosides, with the rate constant value of the malonyl ginsenosides being 3-60 times that of the neutral ginsenosides. At the same temperature, the effect of microwave heating on the degradation of ginsenosides was the same as that of conventional heating.

Cooking↗
PubMed1999

Simultaneous quantification of ginsenosides in American ginseng (Panax quinquefolium) root powder by visible/near-infrared reflectance spectroscopy.

Near-infrared reflectance spectroscopy (NIRS) was examined as a possible alternative to high-performance liquid chromatography (HPLC) for the analysis of ginsenosides from American ginseng (Panax quinquefolium) root powder (n = 26). NIR spectra were collected over 400-2500 nm. For each sample and individual ginsenoside quantified by HPLC, spectral data were regressed against the chemical data to develop prediction equations. The spectral prediction equations produced high correlation coefficient (1-VR) values and low standard errors of cross validation (SECV) values for the determination of individual and total ginsenosides. The contents of individual ginsenosides, Rb(1), Rb(2), Rc, Rd, Re, Rg(1), Ro, m-Rb(1), m-Rb(2), m-Rc, m-Rd, and total ginsenosides (X +/- SECV) were (1.29+/-0.18)%, (0.273+/-0.096)%, (0.298+/-0.052)%, (0.091+/-0.027)%, (1. 015+/-0.114)%, (0.116+/-0.018)%, (0.25+/-0.040)%, (0.776+/-0.116)%, (0.197+/-0.074)%, (0.239+/-0.083)%, (0.143+/-0.042)%, and (4.393+/-0.283)%, respectively. The (1-VR) values of cross validation were 0.877, 0.872, 0.955, 0.834, 0.899, 0.919, 0.325, 0.849, 0.902, 0.877, 0.871, and 0.963, respectively. Results indicated that the NIRS method could be used for the analysis of the major ginsenosides, Rb(1), Re, and m-Rb(1), as well as the total ginsenosides in American ginseng.

Calibration↗
PubMed1998

[Thiamine status of university teacher families in Changsha].

To evaluate the thiamine status of the population consuming the refined cereals and its products, we studied thiamine concentration in 23 food samples and human urine, and three-day dietary survey was conducted. The results showed that the thiamine content in the staple food was much lower than that in the raw material. The thiamine intake from diet was below to 80% RDA in 42.8% investigated families and the thiamine energy ratio was lower than 0.5 mg/4186.8 kJ in 71.5% of them. For the ratio of urinary tiamine (mg)/urinary inosine (g), 51.3% subjects exhibited decreased excretion, especially in the school-age children. We conclude that those people who take the refined cereals and its products as a staple food, is in the risk of thiamine deficiency.

Adolescent↗