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Biomedical subjects

F Chen

Publications and source records attributed to F Chen.

At least 181 records · Page 10Linked to original sources
PubMed2000

Sarcoplasmic reticulum Ca(2+)ATPase and cell contraction in developing rabbit heart.

The purpose of the present study was to determine whether age-related changes in the expression and function of the cardiac isoform of the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2a) play a role in SR Ca(2+)release and cell contraction. SERCA2a protein levels and subcellular localization were compared between fetal, neonatal, juvenile and adult New Zealand White rabbits. Studies of SERCA function in isolated myocytes were performed in situ by examining the rate of reloading of the SR Ca(2+)stores following caffeine-induced depletion. We found that significant quantities of SERCA2a were present early in immature heart and that SERCA2a expression reached adult levels within 15-30 days after birth. Furthermore, SERCA2a protein is present as a series of transverse striations within the cell as early as 1 day of age. In contrast to previous studies of SERCA in vitro, the SERCA protein function in situ was found to be comparable between neonatal and adult myocytes in maintaining SR Ca(2+)stores. These results indicate that the paucity of SR Ca(2+)release in immature ventricular cardiac myocytes is not the result of immaturity in SERCA2a expression.

Age Factors↗
PubMed2000

Molecular cloning of junctin from human and developing rabbit heart.

Canine junctin is a 26-kDa transmembrane protein found in the sarcoplasmic reticulum (SR) membrane in cardiac and skeletal muscle. Junctin has recently been shown to bind directly to calsequestrin, the ryanodine receptor, and triadin. Junctin is thought to play a role in facilitating (and perhaps regulating) Ca(2+) release from the SR. Immature heart exhibits decreased utilization of SR Ca(2+) stores for cell contraction. We have cloned human and rabbit cardiac junctin and investigated the expression of junctin in developing rabbit heart. Human junctin was cloned from an adult cardiac cDNA library. Rabbit junctin was cloned by RT-PCR. Northern blot analysis demonstrates a single primary mRNA transcript of approximately 2.8 kb in hearts from both species. Sequence analysis demonstrates greater than 97% homology between the predicted amino acid sequences of human, rabbit, and canine junctin in the putative transmembrane domain and subsequent initial 61 amino acid portion of the putative luminal domain. These domains also exhibit sequence homology with triadin. The C-terminal region shows much lower (72 to 75%) sequence homology among the three species. In addition, Northern blot analysis demonstrates that the expression of junctin increases markedly in postnatal rabbit myocardium. These findings suggest that the putative transmembrane domain and subsequent initial portion of the putative luminal domain of junctin play an important role in the binding of junctin to calsequestrin, the ryanodine receptor, and triadin in the postnatal heart. Furthermore, the previously described increase in SR Ca(2+) release with development is associated with the increased expression of junctin.

Adult↗
PubMed2000

Effects of cigarette smoke extract on E-cadherin expression in cultured airway epithelial cells.

To investigate whether the change of E-cadherin (ECD) expression plays a role in the injury and repair of airway epithelial cells (AEC) caused by smoking, porcine AECs were cultured by using an enzyme-dispersed method. After exposure of the AECs to cigarette smoke extract (CSE), the ECD expression in the cells was detected by using immunocytochemistry and in situ hybridization. The results showed that ECD was distributed on the plasma membrane at the cell junctions of AECs. After exposure to 20% CSE, the membranous ECD expression was decreased, the cytoplasmic ECD expression was increased (P < 0.01) as the exposure time went on. But the content of ECD mRNA in the AECs did not chang. It suggests that the change of ECD expression is regulated at the posttranslational level and plays a role in the injury and repair of AEC caused by smoking.

Animals↗
PubMed2000

Pulmonary mucosa-associated lymphoid tissue lymphoma 8 years after resection of the same type of lymphoma of the liver.

A 64-year-old woman presented with hepatic and pulmonary tumors of mucosa-associated lymphoid tissue lymphoma occurring 8 years apart. The present case carries the possibility of pulmonary metastasis of hepatic lymphoma or double primary lymphoma. Mucosa-associated lymphoid tissue lymphomas tend to develop in the extranodal primary organ, rarely developing systemically among extranodal organs as in our case. Our experience is useful in understanding the progress and outcome of mucosa-associated lymphoid tissue lymphoma.

Female↗
PubMed2000

Fluorimetric determination of methylmercury as an ion-association complex with rhodamine B in the presence of iodide.

A fluorimetric method for the determination of methylmercury was established. The method was based on the formation of an ionic pair between iodide-methylmercury-rhodamine B in hydrochloric acid, which can be extracted with benzene. The fluorescence emission was measured at lambda(ex)/lambda(em) 575/590 nm, and the experimental variables and possible interference were studied. The linear calibration range was 4 x 10(-8) mol/L to approximately 5 x 10(-7) mol/L with a correlation coefficient of 0.9992. The detection limit was 1 x 10(-8) mol/L. The method was used to determine methylmercury in human hair. The recovery was in the range of 91% to 105% and the relative standard deviation was 2.8%. The results agreed with those obtained by gas chromatography with electron capture detection.

Calibration↗
PubMed2000

A highly sensitive fluorimetric method for the determination of fluoride in biological material with Al3+-calcein complex.

A highly sensitive fluorimetric method for the determination of fluoride was established. The method was based on quenching of the fluorescence of the Al3+-calcein complex in CCl3COOH-CH3COOK buffer solution by fluoride. The fluorescence emission was measured at lambdaex/lambdaem 480/503 nm, and the experimental variables and interference in this determination were studied. The linear calibration range was 0.8 ng/mL to 150 ng/mL and the detection limit was 0.2 ng/mL. The method was applied to determine fluoride in biological materials. The recovery was in the range of 96.3% to 104.7% and the relative standard deviation was 4.6%. The results obtained from the certified reference material by the present method agreed with the certified values.

Aluminum↗
PubMed2000

Determination of vitamin B12 in pharmaceutical preparations by a highly sensitive fluorimetric method.

A fluorimetric method for the determination of vitamin B12 has been developed. The fluorescence emission was measured at lambda(ex)/lambda(em)275/305 nm in phosphate buffer solution (pH 7.0), and the experimental variables and possible interference were studied. The linear calibration range was 1.000 ng/mL to 100.0 ng/mL with a correlation coefficient of 0.9994 and a detection limit of 0.1 ng/mL. The method is rapid, simple and highly sensitive. It was used to determine vitamin B12 in pharmaceutical preparations. The recovery was 96%-98% and the relative standard deviation was in the range of 1.8%-2.7%. The results agreed with those obtained by spectrophotometry.

Culture Media↗
PubMed2000

Experimental and clinical experience using tissue regeneration for urethral reconstruction.

Various urethral conditions often require additional tissue for reconstruction. Although several innovative tissues have been proposed for possible use as free grafts for urethral repair, all have specific advantages and disadvantages. The use of these tissues may be associated with additional procedures for graft retrieval, prolonged hospitalization, and donor-site morbidity. For these reasons, alternate materials have been sought for urethral repair. Our laboratory has developed an acellular collagen matrix that has shown adequate urothelial-cell epithelialization and urethral-tissue regeneration both experimentally and clinically. After a 3-year follow-up period, all patients who have had their urethras reconstructed with the acellular matrix are doing well, showing no clinical change from their immediate postoperative results. Other acellular materials may soon be tried clinically. Long-term studies need to be conducted before any of these materials can be accepted for routine use in urethral reconstructive procedures.

Animals↗
PubMed2000

Dynamic process of information transmission complexity in human brains.

Based on a complexity analysis of mutual information transmission of EEG developed by us [Xu J, Liu Z, Liu R, Yang Q (1997) Physica D 106: 363-374], dynamic processes of the complexity of mutual information transmission in human brains were studied. To diminish possible problems due to coarse graining preprocessing, some new measures of complexity were used. The results show that, just before and after generalized seizures, the complexities of almost all information transmission between different brain areas drop significantly; there is also a temporary decrease of complexity when subjects shift their attention. The above facts suggest that there is a transient decrease of information transmission complexity when brain state changes occur suddenly. Mental arithmetic tasks activate the left temporal lobe to exchange more information with other brain areas. The results hint that the methods used here might be an approach to observe quick processes in the living brain.

Adult↗
PubMed2000

Conversion of guaiacyl to syringyl moieties on the cinnamyl alcohol pathway during the biosynthesis of lignin in angiosperms.

Aglycons derived from 4-O-beta-D-glucosides of both caffeyl and 5-hydroxyconiferyl alcohols were incorporated into guaiacyl (G) and syringyl (S) units in the lignin of newly formed xylem of several angiosperms. It is likely that these aglycons enter the cinnamyl alcohol pathway as intermediates in the introduction of methoxyl groups onto aromatic rings, and serve as precursors for the biosynthesis of lignin. The S/G ratio in this pathway was coincident with the ratio in the cell wall lignin of each tree. Our results indicate that the cinnamyl alcohol pathway involves the same mechanisms as the cinnamic acid and cinnamyl CoA pathways and they suggest that this novel pathway might be part of a metabolic grid in the biosynthesis of lignin.

Cinnamates↗
PubMed2000

Cloning and expression analysis of murine lupin, a member of a novel gene family that is conserved through evolution and associated with Lupus inclusions.

We describe here the first full-length sequence of a member of a novel gene family encoding a protein in the mouse that we call Lupin. Lupin is homologous to a human protein previously called p36, which was purified from alpha-interferon-treated cells that formed lupus inclusions. Lupus inclusions are dense intracellular deposits found in endothelial cells and lymphocytes of patients with systemic lupus erythematosis and AIDS. Proteins closely related to Lupin exist in evolutionarily divergent species including Caenorhabditis elegans, Drosophila and zebrafish. At least one other lupin-related gene is expressed in the mouse and in man. Lupin is expressed in mouse embryos and adults, notably in liver, spleen, central nervous system, multiple epithelia and all types of muscle. In skeletal muscle, expression analysis suggests that Lupin associates with the contractile apparatus.

5'-Nucleotidase↗
PubMed2000

Photocatalytic degradation of AZO dyes by supported TiO2 + UV in aqueous solution.

The photocatalytic degradation performance of photocatalysts TiO2 supported on 13-X, Na-Y, 4A zeolites with different loading content was evaluated using the photocatalytic oxidation of dyes direct fast scarlet 4BS and acid red 3B in aqueous medium. The results showed that the best reaction dosage of TiO2-zeolite catalysts is about 2 g/l and the photocatalytic kinetics follows first order for all supported catalysts. The photocatalytic activity order of the three series catalysts is 13X type >Y type >4A type. The physical state of titanium dioxide on the supports is evaluated by X-ray photoelectron spectra (XPS), powder X-ray diffraction (XRD), BET, and FTIR.

Azo Compounds↗
PubMed2000

Identification of the subcellular localization of daunorubicin in multidrug-resistant K562 cell line.

We examined the subcellular distribution of daunorubicin (DNR) in resistant K562 cell line which overexpress the P-glycoprotein by confocal laser scanning microscopy. Three fluorescent probes - Rhodamine123, neutral red, NBD-ceramide, which stain the mitochondria, lysosomes, Golgi apparatus respectively, were used to identify the nature of the subcellular compartment sequestering daunorubicin. In sensitive k562 cell line, nuclear and cytoplasmic DNR fluorescence was intense and diffuse. In contrast, resistant K562 cell line showed a different DNR distribution. A bright fluorescence signal was located in the perinuclear region and peripheral plasma, the nucleus and other cytoplasmic region appear as empty, as suggested by the distribution of fluorescent probe Rhodamine123 specifically for mitochondria. Verapamil, an effective resistance modulator in P-glycoprotein MDR cells, restored the DNR distribution closer to that in the parent cells. Golgic inhibitor brefeldin A and lysosomotropic agent chloroquine had little effect on drug sequestration. Our studies demonstrate that daunorubicin may be sequestered in mitochondrial compartment in the resistant cells and P-glycoprotein plays an important role on mediating DNR transport.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Orientation relationships of martensite variants determined by electron backscatter diffraction

Orientation relationships between the parent phase and 2H type martensite, and between different variants in a plate group of martensite in the CuAlNi shape memory alloy were determined by electron backscatter diffraction. The result reveals clearly that the basal planes of different correspondence variants of the 2H martensite originate from different 110P planes of the parent phase, and the [010]2H axis of each correspondence variant originates from one of the <001>P axes of the parent phase. Our result reveals also the typical relationships of four habit-variants A, B, C and D in a martensite plate group, and that the habit-variants A and C (and equivalenty B and D) are twin-related by an 1212H mirror plane, and the habit-variants A and D (and B and C) are twin-related by an 1012H mirror plane. Usually, variants A and C (and B and D) form spear morphology and variants A and D (and B and C) form fork morphology.

Journal Article↗
PubMed2000

Mutation of conserved aspartates affect maturation of presenilin 1 and presenilin 2 complexes.

Presenilin (PS1 and PS2) holoproteins are transiently incorporated into low molecular weight (MW) complexes. During subsequent incorporation into a higher MW complex, they undergo endoproteolysis to generate stable N- and C-terminal fragments (NTF/CTF). Mutation of either of two conserved aspartate residues in transmembrane domains inhibits both presenilin-endoproteolysis and the proteolytic processing of APP and Notch. We show that aspartate-mutant holoprotein presenilins are not incorporated into the high molecular weight, NTF/CTF-containing complexes. Aspartate-mutant presenilin holoproteins also preclude entry of endogenous wild-type PS1/PS2 into the high molecular weight complexes, but do not affect the incorporation of wild-type holoproteins into lower molecular weight holoprotein complexes. These data suggest that the loss-of-function aspartate-mutants cause altered PS complex maturation, and argue that the functional presenilin moieties are contained in the high molecular weight presenilin NTF/CTF-containing complexes.

Alzheimer Disease↗
PubMed2000

Effects of androgen and ageing on gene expression of vasoactive intestinal polypeptide in rat corpus cavernosum.

OBJECTIVE: To clarify the effects of androgens (testosterone and dihydrotestosterone, DHT) and ageing on gene expression of vasoactive intestinal polypeptide (VIP), assessed as the expression of VIP mRNA, in rat corpus cavernosum. Materials and methods The study comprised 160 male Sprague Dawley rats divided into group A (56 rats, 5 weeks old), group B (50 rats, 10 weeks old) and group C (54 rats, 58 weeks old). Groups A-C were subdivided, respectively, into subgroups 1 (intact controls), 2 (castrated), 3 (castrated but given testosterone undecanoate 25 mg/kg per month by intramuscular injection), 4 (castrated with testosterone undecanoate 50 mg/kg per month) and 5 (treated with finasteride 4.5 mg/kg per day, orally). At 4 and 10 weeks after these treatments half the rats were killed. Serum samples were taken for the measurement of total and free testosterone and DHT, using a radioimmunoassay. Penile samples (corpus cavernosum) were frozen in liquid nitrogen and stored at -80 degrees C. VIP mRNA was estimated using a semi-quantitative reverse-transcription polymerase chain reaction. RESULTS: There was no significant difference in VIP mRNA in rat corpus cavernosum between intact control and castrated subgroups, or subgroups treated with finasteride, in groups A-C, including both the 4- and 10-week old animals (P > 0.05). Penile VIP mRNA was unchanged at any dose of testosterone in the castrated subgroups in all groups (P > 0.05). There was no significant relationship between penile VIP mRNA and ageing (P > 0.05). CONCLUSIONS: The gene expression of VIP in rat corpus cavernosum is independent of androgens (testosterone and DHT) and ageing. Androgens probably induce penile erection by pathways other than VIP; ageing may have little effect on penile VIP mRNA.

Aging↗