Biomedical subjects

Y X Yu

Publications and source records attributed to Y X Yu.

At least 19 recordsLinked to original sources

PubMed2006

Development of a compound-specific carbon isotope analysis method for atmospheric formaldehyde via NaHSO3 and cysteamine derivatization.

A novel method has been developed for the compound-specific carbon isotope analysis of atmospheric formaldehyde using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). The method allows the determination of the delta13C value for atmospheric formaldehyde at nanogram levels with higher precision and lower detection limit. In the present work, atmospheric formaldehyde was collected using NaHSO3-coated Sep-Pak silica gel cartridges, washed out by water, then derivatized by cysteamine of known delta13C value, and the delta13C value of its derivative (thiazolidine) determined by GC/C/IRMS. Finally, the delta13C value of atmospheric formaldehyde could be calculated by a simple mass balance equation between formaldehyde, cysteamine, and thiazolidine. Using three formaldehydes with different delta13C values, calibration experiments were carried out over large ranges of formaldehyde concentrations. The carbon isotope analysis method achieved excellent reproducibility and high accuracy. There was no carbon isotopic fractionation throughout the derivatization processes. The differences in the carbon isotopic compositions of thiazolidine between the measured and predicted values were always <0.5 per thousand, within the specifications of the GC/C/IRMS system. The present method was also compared with the previous 2,4-dinitrophenylhydrazine derivatization method, and this method could be performed with lower analytical error and detection limit. Using this method, four 6-h ambient atmospheric formaldehyde samples were consecutively collected from 8 to 9 March 2005. The results showed that the delta13C values of atmospheric formaldehyde were different during the daytime and nighttime. This method proved suitable for the routine operation and may provide additional insight on sources and sinks of atmospheric formaldehyde.

Air Pollutants↗

PubMed2001

Expression analysis and chromosome location of a novel gene (H11) associated with the growth of human melanoma cells.

We have previously described the isolation of a new human gene, H11, that codes for a 25 kDa phosphoprotein with autokinase activity the expression of which is required for cell growth. The data described in this report extend these findings. Using FISH and M-FISH we show that H11 which maps at chromosome site 12q24.1-12q24.31 is not involved in chromosomal translocations. The tissue distribution of H11 mRNA is restricted, with expression being most abundant in skeletal muscle, heart, prostate and placenta. The H11 protein is cytoplasmic and it is associated with the plasma membrane. Cell surface localization in particulate aggregate formations suggests that it may be complexed to proteins involved in the transfer of extracellular growth signals.

Blotting, Northern↗

PubMed2000

A novel human gene similar to the protein kinase (PK) coding domain of the large subunit of herpes simplex virus type 2 ribonucleotide reductase (ICP10) codes for a serine-threonine PK and is expressed in melanoma cells.

The large subunit of herpes simplex virus type 2 ribonucleotide reductase (ICP10) is a multifunctional protein that contains a serine-threonine protein kinase (PK) activity (Nelson, J. W., Zhu, J. , Smith, C. C., Kulka, M., and Aurelian, L. (1996) J. Biol. Chem. 271, 17021-17027). Phylogenetic analyses indicated that ICP10 PK belongs to a distinct subfamily of growth factor receptor serine-threonine PKs that are characterized by their ability to function with a limited number of conserved catalytic motifs (Hunter, J. C. R., Smith, C. C., and Aurelian, L. (1995) Int. J. Onc. 7, 515-522). Here, we report the isolation and characterization of a novel gene, designated H11, that contains an open reading frame of 588 nucleotides, which encodes a protein similar to ICP10 PK. The H11 protein has Mn(2+)-dependent serine-threonine-specific PK activity as determined with a GST-H11 fusion protein and by immununocomplex PK/immunoblotting assays of 293 cells transfected with a H11 eukaryotic expression vector. PK activity is ablated by mutation of Lys(113) within the presumtive catalytic motif II (invariant Lys). 293 cells stably transfected with H11 acquire anchorage-independent growth. Endogenous H11 RNA and the H11 phosphoprotein are expressed in melanoma cell lines and primary melanoma tissues at levels higher than in normal melanocytes and in benign nevi. Melanoma cell proliferation is inhibited by treatment with antisense oligonucleotides that inhibit H11 translation, suggesting that H11 expression is associated with cell growth.

Amino Acid Sequence↗

PubMed2000

Recovery of NV knockout infectious hematopoietic necrosis virus expressing foreign genes.

Infectious hematopoietic necrosis virus (IHNV) is a Novirhabdovirus and is the causative agent of a devastating acute, lethal disease in wild and farmed rainbow trout. The virus is enzootic throughout western North America and has spread to Asia and Europe. A full-length cDNA of the IHNV antigenome (pIHNV-Pst) was assembled from subgenomic overlapping cDNA fragments and cloned in a transcription plasmid between the T7 RNA polymerase promoter and the autocatalytic hepatitis delta virus ribozyme. Recombinant IHNV (rIHNV) was recovered from fish cells at 14 degrees C, following infection with a recombinant vaccinia virus expressing the T7 RNA polymerase (vTF7-3) and cotransfection of pIHNV-Pst together with plasmids encoding the nucleoprotein N (pT7-N), the phosphoprotein P (pT7-P), the RNA polymerase L (pT7-L), and the nonvirion protein NV (pT7-NV). When pT7-N and pT7-NV were omitted, rIHNV was also recovered, although less efficiently. Incidental mutations introduced in pIHNV-Pst were all present in the rIHNV genome; however, a targeted mutation located in the L gene was eliminated from the recombinant genome by homologous recombination with the added pT7-L expression plasmid. To investigate the role of NV protein in virus replication, the pIHNV-Pst construct was engineered such that the entire NV open reading frame was deleted and replaced by the genes encoding green fluorescent protein or chloramphenicol acetyltransferase. The successful recovery of recombinant virus expressing foreign genes instead of the NV gene demonstrated that the NV protein was not absolutely required for viral replication in cell cultures, although its presence greatly improves virus growth. The ability to generate rIHNV from cDNA provides the basis to manipulate the genome in order to engineer new live viral vaccine strains.

Animals↗

PubMed1999

Partial mapping and sequencing of a fish iridovirus genome reveals genes homologous to the frog virus 3 p31, p40 and human eIF2alpha.

Iridovirus-like pathogens have been recognized as a cause of serious systemic diseases among feral, cultured and ornamental fish in the recent years. Mortalities of fish due to systemic iridovirus infection reaching 30-100% were observed in Europe, Australia, Japan and Thailand. Up to now, the molecular biology of these important pathogens has been poorly documented. To get better insights on the genomic organization of these piscine iridoviruses, we have constructed a cosmid viral DNA library from the epizootic hematopoietic necrosis virus (EHNV). Two recombinant cosmids (Cos7 and Cos12) have been selected for systematic sequencing. Cos7 and 12 are localized side by side along the genome and cover the 2/3 part of the total EHNV genome which has been estimated to be approximately 101.47 kb in length. Thirty five kilobase pairs (kbps) from Cos7 and 10 kbps from Cos12 have been determined. Sequence analysis revealed open reading frames (ORF) sharing homologies with sequences from the Frog virus 3 such as the p31 and p40 proteins. Among the others identified ORFs, some of them presented homologies with known protein sequences, such as the human eIF2alpha protein, and some did not show any significant homologies with sequences available in the databases. But, none were related to Lymphocystis virus, a member of the Iridoviridae family, for which the full genome nucleotide sequence has been determined.

Amino Acid Sequence↗

PubMed1998

OFQ reverses the kappa-opioid receptor-mediated depression of calcium current in rat dorsal root ganglion neurons.

Since the characterization of orphanin FQ (OFQ), the endogenous ligand of ORL1 receptor, much work has focused on its physiological functions. OFQ was reported to antagonize the effect of opioid-induced antinociception, although its mechanism remains obscure. In the present study, whole-cell patch clamp recording technique was used to observe if OFQ can reverse the inhibition of calcium current produced by the kappa-opioid agonist U50,488H (U50) in acutely dissociated rat DRG neurons. The concentrations of OFQ and U50 were 50 nM and 10 microM, respectively. Among 49 cells recorded, the calcium channel currents of 37 (75.5%) cells were inhibited by U50, of which 30 (81.1%) cells could be reversed by OFQ. It was interesting to note the similarity between OFQ and the well characterized anti-opioid peptide CCK-8 in that it reversed kappa-opioid receptor agonist induced suppression on calcium channel current, while by itself showed a calcium channel suppressive effect. Thus OFQ may be regarded as another anti-opioid peptide.

Animals↗

PubMed1998

Immunogenicity of live attenuated SA14-14-2 Japanese encephalitis vaccine--a comparison of 1- and 3-month immunization schedules.

Live attenuated SA14-14-2 Japanese encephalitis (JE) vaccine has been safe and effective in >100 million immunized children, but its current administration schedule of two doses given a year apart does not lend itself to inclusion in established Expanded Program of Immunization (EPI) schedules of childhood immunization. Immune responses to immunization at shorter intervals were compared in middle-school-aged children immunized with two doses separated by 1 month (n = 116) or 2.5 months (n = 115). Two vaccine lots were compared. Seroconversion to the vaccine was observed in 100% of vaccinees immunized in the 1-month schedule and in 94% (lot 2) and 100% (lot 1) of vaccinees immunized in the 2.5-month schedule. Geometric mean titers were almost 2-fold higher with the longer schedule. The routine administration of JE SA14-14-2 vaccine to infants in an EPI schedule should be possible using either interval.

Adolescent↗

PubMed1996

Demonstration of a fibre afferents with overlapping receptive fields in humans.

According to previous data peripheral nerves may lack a detailed microanatomical organization. Nevertheless, stimuli within restricted skin areas might excite more than one afferent of the same modality. Since, as recently demonstrated, peripheral myelinated afferents are at least partially organized by both modality and somatotopy it might be possible to demonstrate such a phenomenon electrophysiologically provided that adequate procedures are used. To address this issue we recorded activity in single myelinated afferents supplying the hand with concentric needle electrodes. A combination of electrical and/or natural stimuli applied to the area where rapidly adapting (RA) or slowly adapting type I (SAI) fibres ended demonstrated that fibres of the same functional class may exhibit overlapping receptive fields in the skin.

Action Potentials↗

PubMed1996

Cholecystokinin octapeptide reverses the kappa-opioid-receptor-mediated depression of calcium current in rat dorsal root ganglion neurons.

Although the cholecystokinin octapeptide (CCK-8) is reported to antagonize the kappa-opioid-receptor-mediated analgesic effect in spinal cord, its mechanism and sites of action remain obscure. In the present study, the whole-cell patch-clamp recording technique was employed to examine the effect of kappa-opioid agonist U50488H on voltage-gated calcium channels and the interaction between the CCK-8 and U50488H in acutely isolated rat dorsal root ganglion neurons. The results indicate that the calcium currents elicited in dorsal root ganglion neurons can be depressed by U50488H, an effect readily reversed by the kappa-opioid receptor antagonist Nor-BNI or by the antiopioid peptide CCK-8. The effect of the CCK-8 can be abolished by the CCK-B receptor antagonist, L365,260. While CCK-8 showed a potent opioid-reversal effect, it by itself exerted a slight inhibitory effect on calcium current. This novel observation in the dorsal root ganglion neurons indicates that CCK-8 can antagonize the kappa-opioid-receptor-mediated depressant effect on voltage-gated calcium current, and this antagonizing effect appears to be mediated via CCK-B receptor.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed1996

Cholecystokinin octapeptide reverses the inhibitory effect induced by electroacupuncture on C-fiber evoked discharges.

Extracellular single unit recordings were made from spinal dorsal horn wide dynamic range neurons in spinal transected, urethane-anesthetized rats. The unit discharges elicited by noxious electrical stimulation of the hind paw were suppressed by electroacupuncture (15 Hz, 0.3 ms, 3 mA, 30 min) placed at the hind leg points (S-36 and SP-6). Local spinal superfusion with naloxone (20 micrograms/15 microliters) or CCK-8 (10 ng/15 microliters) attenuated, whereas CCK-B receptor antagonist L365,260 (2.5 micrograms/15 microliters) enhanced the electroacupuncture effect. These findings provide further evidence for the notion that CCK-8, in the spinal cord, functions as an antiopioid substrate that antagonizes opioid- or electroacupuncture-induced analgesia.

Animals↗

PubMed1996

[Current status of the application of patch-clamp technique and its combinations with other techniques].

The Patch-clamp technique, as an advanced electrophysiological technique, has been widely used for research in the life science research field. A recent trend is to combine this technique with other techniques, such as the Fura-2 microfluorimetry for measuring the concentration of Ca2+, electrochemical detection with carbon-fiber electrode (i.e. amperometric detection or amperometry), and single-cell reverse transcription of RNA followed by the polymerase chain reaction (RT-PCR). This article is to summarize the current status of the use of patch-clamp technique and its combinations with other techniques in solving problems related with transmembrane signal transduction in neurobiology.

Animals↗

PubMed1995

Comparative study of the analgesic and paralytic effects induced by intrathecal dynorphin a in rats.

Intrathecal injection of dynorphin A produced dual effects on sensory and motor functions in the spinal cord of the rat. At a dose of 5 nmol, dynorphin A produced an increase in tail flick latency (TFL) as well as a reversible motor paralysis as assessed by change in the angle of inclined plane. At a dose of 10 or 20 nmol, dynorphin produced a motor paralysis lasting for up to 24 hours. The effect of dynorphin A on the sensory function of the spinal cord was shown by an increase in the vocalization threshold induced by electrical stimulation of the tail, at dose range of 1.25-10 nmol, with a quick onset (5 min) and relatively short duration (within 60 min). Unlike tail flick reaction which involves spinal motor function, tail stimulation-induced vocalization threshold is a relatively pure index for spinal nociceptive activities. The differential effect of dynorphin on sensory and motor function was supported by the evidence that (1) dynorphin-induced analgesic effect (increase in vocalization threshold) was naloxone reversible, whereas dynorphin-induced motor paralysis was naloxone resistant. (2) Nor-BNI, a specific antagonist for kappa opioid receptor, blocked the sensory effect of dynorphin, but had no influence on motor effect of dynorphin. It is thus concluded that dynorphin has both analgesic and paralytic effects in spinal cord. The analgesia shown by an increase of vocalization threshold is an opioid effect, most probably mediated by kappa opioid receptor; the paralytic effect, however, is a non-opioid effect. The increase of TFL induced by dynorphin involves both sensory (analgesia) and motor (paralysis) effects.

Analgesics↗

PubMed1995

Changes in the content of immunoreactive dynorphin in dorsal and ventral spinal cord of the rat in three different conditions.

Previous study in our group demonstrated that dynorphin exerted a significant analgesic effect in spinal cord, and electroacupuncture (EA) of high frequency (100 Hz) produced analgesia which was mediated by dynorphin released in spinal cord. However, no data are up to nowadays available for demonstrating either from anterior horn or from dorsal horn the dynorphin comes. Using radioimmunoassay, we found in the present study that ir-dynorphin content in dorsal horn was 10 times more than in anterior horn, which were 11.24 +/- 0.91 pmol/10 mg protein and 1.08 +/- 0.20 pmol/10 mg protein, respectively. Stimulation of 100 Hz EA for 30 min produced a significant increase of ir-dynorphin content in dorsal horn, in contrast, no change of ir-dynorphin content was found in anterior horn. For the meanwhile, a significant elevation of ir-dynorphin was induced by 100 Hz EA in cerebrospinal fluid. It is concluded according to these data that EA, as a stimulation in physiological condition, elevates the content of ir-dynorphin only in dorsal horn, and induces release of dynorphin in loci. The released dynorphin acts on dorsal horn to mediate the analgesia of EA.

Animals↗

PubMed1995

Cholecystokinin octapeptide reverses mu-opioid-receptor-mediated inhibition of calcium current in rat dorsal root ganglion neurons.

Cholecystokinin octapeptide (CCK-8) is reported to antagonize the analgesic effect produced by mu- and kappa- but not delta-opioid agonist in spinal cord. However, the mechanisms of interaction remain obscure. In the present study, whole-cell patch-clamp recording was performed on acutely isolated rat dorsal root ganglion (DRG) neurons to evaluate the effects of the highly specific mu-opioid agonist ohmefentanyl and the delta-opioid agonist DPDPE on voltage-gated calcium channels and the possible interaction between CCK-8 receptor and mu- or delta-opioid receptor. The results indicated that ohmefentanyl, but not DPDPE, can suppress the voltage-gated calcium currents elicited in DRG neurons, an effect readily reversed by naloxone or by the antiopioid peptide CCK-8. The effect of CCK-8 can in turn be abolished by the CCK-B receptor antagonist L365,260. CCK-8 used by itself has no enhancing effect, but rather a depressant effect, on calcium currents. However, used simultaneously with ohmefentanyl, CCK-8 shows a clear-cut reversal of depression of the mu-opioid. We conclude that the depressant effect produced by mu-opioid on voltage-gated calcium current in DRG neurons can be antagonized by CCK-8 through CCK-B receptor located in the same neuron. The delta-opioid DPDPE has no direct effect on the voltage-gated calcium current in DRG neurons.

Animals↗

PubMed1994

[Evaluation of multiple prognostic factors in colorectal cancer].

A multivariate stepwise discriminant analysis was performed to evaluate the prognostic value of DI, PI, AgNOR, p21D, CEAD and several clinicopathological features (age, sex, tumor location, histological grading, typing and staging) in 83 patients with colorectal cancer who underwent radical surgery. A fisher's discriminant function was established by using 6 selected items (staging, grading, DI, PI, AgNOR and p21D). It's efficiency, sensitivity and specificity were 91.28%, 87.18%, and 95.45% respectively. Correlative studies on DI, PI, AgNOR and p21D indicated that they are independent factors influencing prognosis. Therefore, in addition to Dukes's classification and histopathological grading of the tumor, these molecular biological factors can be considered as a new clue to evaluation of patients prognosis.

Adult↗

PubMed1994

[p21ras expression, DNA ploidy and prognosis in colorectal cancer].

83 colorectal cancer patients who underwent radical surgery were studied. Serial sections were carried out for detection of p21ras expression level by means of immunohistochemical assay combined with image analysis technique, measurement of DNA ploidy by flow cytometry and re-confirmation of diagnosis. We found that the high level of p21ras expression indicated a group of tumors with more aggressive behavior and worse prognosis. The five-year survival rate was only 26.83% in patients with p21D > or = 0.24 tumor, compared with 78.57% in those with p21D < 0.24 tumor. Five-year survivors tended to display diploid and had lower p21D. Detection of p21ras expression level (p21D) and DNA index in tumors may be helpful in predicting the outcome of colorectal cancer patients.

Adult↗

PubMed1994

Investigation on inactivated epidemic hemorrhagic fever tissue culture vaccine in humans.

From 1988 to 1992, 2479 volunteers were immunized by inactivated Meriones unguiculatus kidney cell (MUKC) vaccine. Their seroconversion rates of neutralizing antibody were about 90% after 3 doses of the vaccine. No side effects were found. The vaccine stored for 14 months at 4 degrees C still had good immunogenicity. It was shown that the vaccine was safe, effective and stable. Detailed observation was made in 75 volunteers. The results showed that the seroconversion rate by plaque reduction neutralization test in 3 doses group was higher than that in 2 doses group; but the results by reversed passive hemagglutination (RPHI), immunofluorescence assay (IFA) and ELISA were similar. Different immunization procedures (3 x 1 ml during 28 days or 3 x 1 ml during 60 days), injection routes (im or sc) and vaccine forms (containing adjuvants or not) showed no significant difference. If secondary immunization (one dose) was given one year after primary immunization, geometric mean titre of the neutralizing antibody was two fold higher than that after primary immunization.

Animals↗

PubMed1993

[Fourteen cases of Riedel's struma: review of the literature].

Riedel's struma, a disorder of unknown aetiology, shows that aggressive fibrosis replaces the normal structure of the thyroid. The fibrosis characteristically spreads beyond the capsule with involvement of the adjacent structures. Fourteen patients were encountered from 4501 thyroidectomies at this hospital in a period of 33 years. The aetiology, pathology, clinical features and methods of treatment were discussed.

Adult↗