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Biomedical subjects

J Xu

Publications and source records attributed to J Xu.

At least 217 records · Page 12Linked to original sources
PubMed2001

Mobilization of the phrenic nerve in the thoracic cavity by video-assisted thoracic surgery. Techniques and initial experience.

BACKGROUND: The use of video-assisted thoracic surgery (VATS) techniques to mobilize the phrenic nerve in the thoracic cavity for neurotization after brachial plexus injury was studied. METHODS: From August 1999 to January 2000, 10 men and 1 woman with brachial plexus injury (left side in 5 and right side in 6) joined the study group. Their ages ranged from 20 to 38 years (average, 28 years). Supine after general anesthesia, all the patients had double-lumen trachea cannulas to guarantee complete lung collapse on the operative side. Three port incisions were made to allow introduction of the following: a 10-mm Stryker endoscope through the sixth intercostal space 2 cm medial to the anterior axillary line, one instrument for manipulation in the anterior axillary line of the third intercostal space, and another in the second intercostal space about 2 cm lateral to the parasternal line. The nerve was mobilized with two common long Mixter clamps and some endoscopic instruments by blunt and sharp dissection. RESULTS: All patients were managed successfully without severe complications. The mean additional length of phrenic nerves by this technique was 16 cm. CONCLUSIONS: Mobilization of the phrenic nerve by VATS is a safe and minimally invasive method for elongating the nerve for neurotization after brachial plexus injury.

Adult↗
PubMed2001

Metabolism and functions of highly unsaturated fatty acids: an update.

This review briefly examines the recent progress in knowledge about the synthesis and degradation of highly unsaturated fatty acids (HUFA) and their functions. Following the cloning of mammalian Delta6-desaturase (D6D), the D6D mRNA was found in many tissues, including adult brain, maternal organs, and fetal tissue, suggesting an active synthesis of HUFA in these tissues. The cloning also confirmed the long-postulated hypothesis that the same pathway is followed in n-6 and n-3 HUFA synthesis. Dietary n-6 and n-3 HUFA both induce fatty acid oxidation enzymes in peroxisomes when compared to their respective precursor polyunsaturated fatty acids. This suggests that peroxisomes may be the primary site of HUFA degradation when HUFA are supplied in excess from the diet. Peroxisome proliferators strongly induce the enzymes for the HUFA synthesis. The mechanism of this induction is currently unknown. Recent studies revealed new HUFA functions that are not mediated by eicosanoids. These functions include endocytosis/exocytosis, ion-channel modulation, DNA polymerase inhibition, and regulation of gene expression. These new discoveries will enable us to re-examine the underlying mechanisms for the classical symptoms of essential fatty acid deficiency as well as vitamin E deficiency. Progress has also been made in understanding the mechanism by which dietary HUFA reduce body fat deposition. One mechanism is induction of genes for fatty acid oxidation, which is mediated by peroxisome proliferator-activated receptor-alpha. Another likely mechanism is that HUFA suppress genes for fatty acid synthesis by reducing both mRNA and protein maturation of sterol regulatory element binding protein-1.

Animals↗
PubMed2001

The incidence of cytoplasmic fragmentation in mouse embryos in vitro is not affected by inhibition of caspase activity.

OBJECTIVE: To investigate the relationship between cytoplasmic fragmentation and caspase activity in the mouse embryo. DESIGN: Experimental laboratory study. SETTING: University gynacology unit. ANIMAL(S): One-cell zygote of mouse (MF1 x BALB/c). INTERVENTION(S): Mouse embryos were treated with caspase inhibitors: benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone (z-VAD-fmk) and benzyloxycarbonyl-Asp-glu-Val-Asp-fluoromethyl ketone (Z-DEVD-fmk). MAIN OUTCOME MEASURE(S): Morphological development of the embryo, proportion of fragmented embryos, caspase-3-like activity, DNA breakage, and phosphatidylserine exposure in blastomeres. RESULT(S): The proportion of embryo reaching two-cell, three- to four-cell, and morula stage at 48, 72, and 96 hours after hCG administration, respectively, were comparable between the control embryos and those treated with either z-VAD-fmk or z-DEVD-fmk, at three concentrations (10 microM, 50 microM, and 200 microM). Although the inhibitors suppressed the caspase-3-like activity in the embryo fragment before compaction and decreased DNA breakages, there was no statistically significant difference in the percentage of fragmented embryo between the control and those treated with caspase inhibitors. The inhibitors did not affect the incidence of phosphatidylserine exposure in the blastomere of the treated embryos. CONCLUSION(S): Cytoplasmic fragmentation in precompaction mouse embryos is not a consequence of caspase-related apoptosis.

Amino Acid Chloromethyl Ketones↗
PubMed2001

Termination of early pregnancy in the scarred uterus with mifepristone and misoprostol.

OBJECTIVE: To analyze the safety and possibility of terminating early pregnancy up to 49 days gestation after cesarean section with mifepristone and misoprostol. METHODS: One-hundred and ninety-two early pregnant women were recruited, of which, 35 cases with uterine cicatrix and 157 cases were no-uterine cicatrix as control group. All of them took 25 mg of mifepristone, b.i.d. for 3 days and 600 microg of misoprostol on the 4th day. RESULTS: Of the 35 cases with uterine cicatrix, 33 achieved complete abortion after medical abortion. The complete abortion rate was 94.29% (95% CI 81-99%) in the cicatrix group and 89.81% (95% CI 75-91%) in the control group. There were no obvious complications detected in the cicatrix group. CONCLUSION: For the termination of early pregnancy in scarred uterus, administration of mifepristone and misoprostol is safe and effective, and a further large series study needs be done to confirm its acceptability as a routine medication in such situations.

Abortifacient Agents↗
PubMed2001

Concordance of interstitial cystitis in monozygotic and dizygotic twin pairs.

Our objective was to determine whether there is a greater concordance of interstitial cystitis (IC) among monozygotic than dizygotic twins. Members of the Interstitial Cystitis Association (ICA) who responded to a survey about first-degree family members with IC symptoms or confirmed IC were requested to identify themselves if they were 1 of a twin pair. Each twin respondent and co-twin were then evaluated via a questionnaire and acquisition of hydrodistention reports as to their meeting modified National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) criteria for IC. Of the co-twins of 8 monozygotic twin respondents, 2 had probable and 3 had confirmed IC compared with none of the co-twins of the 26 dizygotic twin respondents (including 15 female co-twins). There is a greater concordance of IC among monozygotic than dizygotic twin pairs suggesting a genetic susceptibility to IC.

Cystitis, Interstitial↗
PubMed2001

Suppression of tumorigenicity in human ovarian carcinoma cell line SKOV-3 by microcell-mediated transfer of chromosome 11.

To determine the pathogenic role of chromosomes 11 and 17 in the carcinogenesis of human ovarian cancers, neo(R)-tagged chromosome 11 or 17 was transferred from cell lines A9H11 or A9H17, respectively, into the ovarian carcinoma cell line SKOV-3 using microcell-mediated chromosome transfer. The chromosome transfer was verified by polymerase chain reaction detection of the neo(R) gene, fluorescence in situ hybridization detection of an extra chromosome 11, and microsatellite polymorphism detection of an exogeneous chromosome 11. Five SKOV-3/A9H11 hybrids and five SKOV-3/A9H17 hybrid clones were generated. For the chromosome 11 transfer, complete suppression of tumorigenicity was observed in four clones, (11)9-8 and 11(H)7-2, 11(H)8-3, and 11(H)7-2, 100 days post implantation. For the chromosome 17 transfer, no complete suppression of tumorigenicity was observed. However, an increased latency period ranging from 25 to 49 days in contrast to 7 days for the SKOV-3 parental line, and a significant reduction in tumor size was observed. There was no correlation between the in vitro growth rate and the tumorigenicity or length of latency period. Our results demonstrate functionally that chromosome 11 may carry a tumor suppressor gene(s) while chromosome 17 may carry a tumor growth-inhibitor gene(s) for the ovarian carcinoma cell line, SKOV-3.

Animals↗
PubMed2001

Quantitative measurement of the nitrate reductase activity in the human oral cavity.

To quantitatively characterise the nitrate reductase activity in the human oral cavity, a new assay based on holding 20 ml of 10 mg nitrate-N/L solution in the mouth was developed. The mouth assay appeared to relate primarily to the oral cavity surface rather than to the saliva. Nitrite formation in the assay was 50-100 times higher compared to in vitro incubation. In the proposed assay, the nitrite formation linearly increased over a period of 3 min. The average nitrate reductase activity in the oral cavity of 20 subjects was 2.39+/-1.52 microg nitrite-N formed/person x min. The nitrate reductase activity measured for two subjects at different hours varied about 15% for the same subject. The average nitrate reductase activity measured in June for 10 subjects (3.43+/-1.75 microg-N/person x min) was significantly higher than that measured in November for 10 other subjects (1.54+/-0.46 microg-N/person x min). Therefore, the nitrate reductase activity in the oral cavity appears to be influenced by the seasonal conditions. Although the amounts of nitrite formed in the mouth assay increased with increasing levels of nitrate, the rate of nitrate to nitrite reduction decreased with increasing levels of nitrate. The nitrite formation was also affected by the pH, with an optimal pH about 8. The nitrite formation was not influenced by uptake in the mouth of glucose, L-ascorbic acid and L-arginine.

Adult↗
PubMed2001

A kainate receptor increases the efficacy of GABAergic synapses.

Brain functions are based on the dynamic interaction of excitatory and inhibitory inputs. Spillover of glutamate from excitatory synapses may diffuse to and modulate nearby inhibitory synapses. By recording unitary inhibitory postsynaptic currents (uIPSCs) from cell pairs in CA1 of the hippocampus, we demonstrated that low concentrations of Kainate receptor (KAR) agonists increased the success rate (P(s)) of uIPSCs, whereas high concentrations of KAR agonists depressed GABAergic synapses. Ambient glutamate released by basal activities or stimulation of the stratum radiatum increases the efficacy of GABAergic synapses by activating presynaptic KARs, which facilitate Ca(2+)-dependent GABA release. The results suggest that glutamate released from excitatory synapses may also function as an intermediary between excitatory and inhibitory synapses to protect overexcitation of local circuits.

2-Amino-5-phosphonovalerate↗
PubMed2001

Development of dual receptor biosensors: an analysis of FRET pairs.

The development of a dual receptor detection method for enhanced biosensor monitoring was investigated by analyzing potential fluorescent resonance energy transfer (FRET) pairs. The dual receptor scheme requires the integration of a chemical transducer system with two unique protein receptors that bind to a single biological agent. The two receptors are tagged with special molecular groups (donors and acceptors fluorophores) while the chemical transduction system relies on the well-known mechanisms of FRET. During the binding event, the two FRET labeled receptors dock at the binding sites on the surface of the biological agent. The resulting close proximity of the two fluorophores upon binding will initiate the energy transfer resulting in fluorescence. The paper focuses on the analysis and optimization of the chemical transduction system. A variety of FRET fluorophore pairs were tested in a spectrofluorimeter and promising FRET pairs were then tagged to the protein, avidin and its ligand, biotin. Due to their affinities, the FRET-tagged biomolecules combine in solution, resulting in a stable, fluorescent signal from the acceptor FRET dye with a simultaneous decrease in fluorescent signal from the donor FRET dye. The results indicate that the selected FRET pairs can be utilized in the development of dual receptor sensors.

Biosensing Techniques↗
PubMed2001

Deoxycholate induces DNA damage and apoptosis in human colon epithelial cells expressing either mutant or wild-type p53.

Diets rich in fat result in higher concentrations of secondary bile acids or their salts in the colon, which may adversely affect cells of the colonic epithelium. Because secondary bile acids are thought to be genotoxic, exposing colon epithelial cells to secondary bile acids may induce DNA damage that might lead to apoptosis. The requirement for the p53 tumor suppressor gene in such events is unknown. In particular, the effects of secondary bile acids on colon epithelial cells having different p53 tumor suppressor gene status have not been examined. Therefore, HCT-116 and HCT-15 human colon adenocarcinoma cells, which express the wild-type and mutant p53 genes, respectively, were exposed to physiological concentrations of deoxycholate. The cells were then analyzed for evidence of DNA damage and apoptosis. After 2 h of incubation with 300 microM deoxycholate, both cell lines had greater levels of single-strand breaks in DNA as assessed by the comet assay. After 6 h of exposure to deoxycholate, HCT-116 and HCT-15 cells showed morphological signs of apoptosis, i.e., membrane blebbing and the presence of apoptotic bodies. Chromatin condensation and fragmentation were also seen after staining DNA with 4',6-diamidino-2-phenylindole. Other apoptotic assays revealed greater binding of annexin V-fluorescein isothiocyanate, as well as greater post-enzymatic labeling with dUTP-fluorescein isothiocyanate, by both cell lines exposed to deoxycholate. These data suggest that deoxycholate caused DNA damage in colon epithelial cells that was sufficient to trigger apoptosis in a p53-independent manner.

Adenocarcinoma↗
PubMed2001

Cloning and characterization of a novel human TEKTIN1 gene.

Tektins comprise a family of filament-forming proteins that are known to be coassembled with tubulins to form ciliary and flagellar microtubules. A new member of the tektin gene family was cloned from the human fetal brain cDNA library. We hence named it the human TEKTIN1 gene. TEKTIN1 cDNA consists of 1375 bp and has a putative open reading frame encoding 418 amino acids. The predicted protein is 48.3 kDa in size, and its amino acid sequence is 82% identical to that of the mouse, rat, and dog. One conserved peptide RPNVELCRD was observed at position number 323-331 of the amino acid sequence, which is a prominent feature of tektins and is likely to represent a functionally important protein domain. TEKTIN1 gene was mapped to the human chromosome 17 by BLAST search, and at least eight exons were found. Northern blot analysis indicated that TEKTIN1 was predominantly expressed in testis. By in-situ hybridization analysis, TEKTIN1 mRNA was localized to spermatocytes and round spermatids in the seminiferous tubules of the mouse testis, indicating that it may play a role in spermatogenesis.

Amino Acid Sequence↗
PubMed2001

Cell axiality and polarity in plants--adding pieces to the puzzle.

Plant cell polarity is important for cellular function and multicellular development. Classical physiological and cell biological analyses identified cues that orient cell polarity and suggested molecules that translate a cue into intracellular asymmetry. A range of proteins that either mark or are involved in the establishment of a (polar) axis are now available, as are many relevant mutants. These tools are likely to facilitate a dissection of the molecular mechanisms behind cell and organ polarity in the near future.

Cell Differentiation↗
PubMed2001

Novel ceramides from the fungus Lactarium volemus.

Two novel ceramides, lactariamides A (N-2'-hydroxytetracosanoyl-2-amino-3,4-epoxyoctadecan-1-ol (1)) and B ((4E,8E)-N-2'-hydroxyoctadecanoyl-2-amino-9-methyl-4,8-octadecadine-1,3-diol (2)), were isolated from the fungus Lactarium volemus, together with a known compound, cerebroside D (3). Their structures were determined on the basis of chemical evidence and spectral methods.

Agaricales↗
PubMed2001

Molecular cloning and characterization of a novel Dehydrogenase/reductase (SDR family) member 1 genea from human fetal brain.

Short-chain dehydrogenases/reductases (SDR) constitute a large protein family of NAD(P)(H)-dependent oxidoreductase. They are defined by distinct, common sequence motifs and show a wide range of substrate specialisms. By large-scale sequencing analysis of a human fetal brain cDNA library, we isolated a novel human SDR-type dehydrogenase/reductase gene named Dehydrogenase/reductase (SDR family) member 1 (DHRS1). The DHRS1 cDNA is 1411 base pair in length, encoding a 314-amino-acid polypeptide which has a SDR motif. Northern blot reveals two bands, of about 0.9 and 1.4 kb in size. These two forms are expressed in many tissues. The DHRS1 gene is localized on chromosome 14q21.3. It has 9 exons and spans 9.2 kb of the genomic DNA.

Amino Acid Sequence↗
PubMed2001

Weighing the care: physicians' reactions to the size of a patient.

OBJECTIVE: To examine how the weight of a patient affects both the attitudes that physicians hold as well as the treatments that they intend to prescribe. DESIGN: In a six-cell randomized design, physicians evaluated a medical chart of a male or female patient, depicted as either average weight, overweight or obese, who presented with a migraine headache. SUBJECTS: A total of 122 physicians affiliated with one of three hospitals located in the Texas Medical Center of Houston completed the experiment. MEASUREMENTS: Using a standard medical procedure form, physicians indicated how long they would spend with the patient and which of 41 medical tests and procedures they would conduct. They also indicated their affective and behavioral reactions to the patient. RESULTS: The weight of a patient significantly affected how physicians viewed and treated them. Although physicians prescribed more tests for heavier patients, F(2, 107)=3.65, P<0.03, they simultaneously indicated that they would spend less time with them, F(2, 107)=8.38, P<0.001, and viewed them significantly more negatively on 12 of the 13 indices. CONCLUSION: This study reveals that physicians continue to play an influential role in lowering the quality of healthcare that overweight and obese patients receive. As the girth of America continues to increase, continued research and improvements in the quality of such healthcare deserve attention.

Adult↗