PubMed Health⌕ Search

Biomedical subjects

Q Teng

Publications and source records attributed to Q Teng.

At least 19 recordsLinked to original sources
PubMed2006

Anatomically discrete functional effects of adenoviral clostridial light chain gene-based synaptic inhibition in the midbrain.

The gene for the Light Chain fragment of Tetanus Toxin (LC) induces synaptic inhibition by preventing the release of synaptic vesicles. The present experiment applied this approach within the rat midbrain in order to demonstrate that LC gene expression can achieve functionally and anatomically discrete effects within a sensitive brain structure. The deep layers of the superior colliculus/deep mesencephalic nucleus (dSC/DpMe) that are located in the rostral midbrain has been implicated in fear-induced increase of the acoustic startle reflex (fear potentiated startle) but exists in close proximity to neural structures important for a variety of critical functions. The dSC/DpMe of adult rats was injected bilaterally with adenoviral vectors for LC, green fluorescent protein, or vehicle. Synaptobrevin was depleted in brain regions of adenoviral LC expression. LC gene expression in the dSC/DpMe inhibited the increase in startle amplitude seen with the control viral infection, and blocked context-dependent potentiation of startle induced by fear conditioning. Although LC gene expression reduced the absolute amount of cue-specific fear potentiated startle, it did not decrease percent potentiated startle to a cue, nor did it reduce fear-induced contextual freezing, nonspecific locomotor activity, or general health, indicating that its effects were functionally and anatomically specific. Thus, vector-driven LC expression inhibits the function of deep brain nuclei without altering the function of surrounding structures supporting its application to therapeutic neuromodulation.

Adenoviridae↗
PubMed2005

Adenoviral clostridial light chain gene-based synaptic inhibition through neuronal synaptobrevin elimination.

Clostridial neurotoxins have assumed increasing importance in clinical application. The toxin's light chain component (LC) inhibits synaptic transmission by digesting vesicle-docking proteins without directly altering neuronal health. To study the properties of LC gene expression in the nervous system, an adenoviral vector containing the LC of tetanus toxin (AdLC) was constructed. LC expressed in differentiated neuronal PC12 cells was shown to induce time- and concentration-dependent digestion of mouse brain synaptobrevin in vitro as compared to control transgene products. LC gene expression in the rat lumbar spinal cord disrupted hindlimb sensorimotor function in comparison to control vectors as measured by the Basso-Beattie-Bresnahan (BBB) scale (P<0.001) and rotarod assay (P<0.003). Evoked electromyography (EMG) showed increased stimulus threshold and decreased response current amplitude in LC gene-transferred rats. At the peak of functional impairment, neither neuronal TUNEL staining nor reduced motor neuron density could be detected. Spontaneous functional recovery was observed to parallel the cessation of LC gene expression. These results suggest that light chain gene delivery within the nervous system may provide a nondestructive means for focused neural inhibition to treat a variety of disorders related to excessive synaptic activity, and prove useful for the study of neural circuitry.

Adenoviridae↗
PubMed2001

A new complex variant t(4;15;17) in acute promyelocytic leukemia: fluorescence in situ hybridization confirmation and literature review.

We report a 37-year-old male with acute promyelocytic leukemia (APL) harboring a complex translocation (4;15;17). Karyotypic analysis with R-banding of bone marrow cells revealed 46,XY,t(4;15;17)(q21;q22;q21). Fluorescence in situ hybridization analysis using painting probes for chromosomes 4, 15 and 17 and reverse transcriptase polymerase chain reaction analysis revealed three derivative chromosomes: der(4)t(4;15)(q21;q22), der(15)t(4;15;17)(q21;q22;q21), and del(17)(q21q22). This is the third report of such a translocation and the first confirmed by molecular methods. Considering reported similar cases, it is possible that 4q21 is a nonrandom breakpoint in APL with complex translocations and the gene involved in 4q21 should be investigated.

Chromosomes, Human, Pair 15↗
PubMed2001

Determination of perchlorate in tobacco plants and tobacco products.

Previous field and laboratory studies with vascular plants have shown that perchlorate is transported from perchlorate fortified soils and is accumulated in the plant tissues and organs. This paper contains results of preliminary investigations on the occurrence of perchlorate in tobacco plants grown in soils amended with a fertilizer whose nitrogen content is derived from naturally occurring sodium nitrate (Chile saltpeter). Ion chromatography (IC) and capillary electrophoresis (CE) were used for quantitative analysis, while nuclear magnetic resonance (NMR) spectroscopy was used for qualitative analysis of perchlorate. Results show that perchlorate is accumulated by tobacco plants into the leaves from soils amended with fertilizers that contain perchlorate. Also, perchlorate can persist over an extended period of time and under a variety of industrial processes as shown by its presence in off-the-shelf tobacco products including cigarettes, cigars, and pouch and plug chewing tobaccos in concentrations ranging from nd to 60.4 +/- 0.8 mg/kg on a wet weight basis.

Chromatography, Ion Exchange↗
PubMed2001

[A contour map segmentation for laser scanning confocal microscopic biomedical images].

We propose a contour map segmentation method for laser scanning confocal microscopic (LSCM) biomedical images. In this method, an image is first segmented into sub-regions by contour map. Then the sub-regions are merged from top to bottom or from bottom to top, according to a segmentation criterion of intensity homogeneity. The merging procedures continue until no region needs to be merged. The advantage of this method is that the objects with wide intensity ranges and different intensity homogeneity can be segmented properly. In this paper, the region segmentation by contour map is first addressed. Next a region merging according to a segmentation criterion of intensity homogeneity is presented, and then the design of a linear intensity homogeneity segmentation criterion is introduced. Two examples of image segmentation by this method are given at the end of this paper.

Algorithms↗
PubMed2000

Ornithine decarboxylase activity and its gene expression are increased in benign hyperplastic prostate.

BACKGROUND: Ornithine decarboxylase (ODC) is the first key enzyme in the polyamine biosynthesis pathway. Polyamine is believed to participate in cellular proliferation and differentiation. To study the relationship between ODC and the pathogenesis of benign prostatic hyperplasia (BPH), the polyamine levels, ODC activities, and expression of ODC mRNA in benign hyperplastic and normal human prostates were assayed. METHODS: Polyamine contents and ODC activities in tissue extracts were determined by reverse-phase high-performance liquid chromatography and spectrophotometric procedures, respectively. The ODC mRNA levels were assayed by Northern blot analysis. RESULTS: The contents of putrescine, spermidine, and spermine in BPH tissues were 2.2, 3.4, and 6.0 times higher than those in normal tissues, respectively; the ODC activity of BPH tissue was about 3.2 times higher than in normal tissue; the expression level of ODC mRNA in the BPH tissues was greater than that of normal tissues. CONCLUSIONS: The findings imply that 1) the increased ODC activity and polyamine content in prostatic tissue may correlate with the pathogenesis of BPH, and 2) the high level of ODC activity is induced by the overexpression of ODC mRNA.

Adult↗
PubMed2000

Diterpenoid alkaloids from the aerial parts of Aconitum anthora L.

Isolation and identification of six diterpenoid alkaloids, from Aconitum anthora L. are described. All proton detected 2D NMR techniques have been used for unambiguous 1H and 13C chemical shift assignments of guan-fu-base-Y (6). This is the first investigation of the diterpenoid alkaloids of this plant species.

Alkaloids↗
PubMed1999

Secondary structure extensions in Pyrococcus furiosus ferredoxin destabilize the disulfide bond relative to that in other hyperthermostable ferredoxins. Global consequences for the disulfide orientational heterogeneity.

The single cubane cluster ferredoxin (Fd) from the hyperthermophilic archaeon Pyrococcus furiosus (Pf) possesses several unique properties when compared even to Fds from other hyperthermophilic archaea or bacteria. These include an equilibrium molecular heterogeneity, a six- to seven-residue increase in size, an Asp rather than the Cys as one cluster ligand, and a readily reducible disulfide bond. NMR assignments and determination of both secondary structure and tertiary contacts remote from the paramagnetic oxidized cluster of Pf 3Fe Fd with an intact disulfide bond reported previously (Teng Q., Zhou, Z. H., Smith, E. T., Busse, S. C., Howard, J. B. Adams, M. W. W., and La Mar, G. (1994) Biochemistry 33, 6316-6328) are extended here to the 4Fe oxidized cluster WT (1H and 15N) and D14C (1H only) Fds with an intact disulfide bond and to the 4Fe oxidized WT Fd (1H and 15N) with a cleaved disulfide bond. All forms are shown to possess a long (13-member) alpha-helix, two beta-sheets (one double-, one triple-stranded), and three turns outside the cluster vicinity, each with tertiary contacts among themselves as found in other Fds. While the same secondary structural elements, with similar tertiary contacts, are found in other hyperthermostable Fds, Pf Fd has two elements, the long helix and the triple-stranded beta-sheet, that exhibit extensions and form multiple tertiary contacts. All Pf Fd forms with an intact disulfide bond exhibit a dynamic equilibrium heterogeneity which is shown to modulate a hydrogen-bonding network in the hydrophobic core that radiates from the Cys21-Cys48 disulfide bond and encompasses residues Lys36, Val24, Cys21, and Cys17 and the majority of the long helix. The heterogeneity is attributed to population of the alternate S and R chiralities of the disulfide bond, each destabilized by steric interactions with the extended alpha-helix. Comparison of the chemical shifts and their temperature gradients reveals that the molecular structure of the protein with the less stable R disulfide resembles that of the Fd with a cleaved disulfide bond. Both cluster architecture (3Fe vs 4Fe) and ligand mutation (Cys for Asp14) leave the disulfide orientational heterogeneity largely unperturbed. It is concluded that the six- to seven-residue extension that results in a longer helix and larger beta-sheet in Pf Fd, relative to other hyperthermostable Fds, more likely serves to destabilize the disulfide bond, and hence make it more readily reducible, than to significantly increase protein thermostability.

Amino Acid Sequence↗
PubMed1997

Ribose biosynthesis and evidence for an alternative first step in the common aromatic amino acid pathway in Methanococcus maripaludis.

An acetate-requiring mutant of Methanococcus maripaludis allowed efficient labeling of riboses following growth in minimal medium supplemented with [2-(13)C]acetate. Nuclear magnetic resonance and mass spectroscopic analysis of purified cytidine and uridine demonstrated that the C-1' of the ribose was about 67% enriched for 13C. This value was inconsistent with the formation of erythrose 4-phosphate (E4P) exclusively by the carboxylation of a triose. Instead, these results suggest that either (i) E4P is formed by both the nonoxidative pentose phosphate and triose carboxylation pathways or (ii) E4P is formed exclusively by the nonoxidative pentose phosphate pathway and is not a precursor of aromatic amino acids.

Acetates↗
PubMed1997

Characterization of UDP amino sugars as major phosphocompounds in the hyperthermophilic archaeon Pyrococcus furiosus.

The archaeon Pyrococcus furiosus is a strictly anaerobic heterotroph that grows optimally at 100 degrees C by the fermentation of carbohydrates. It is known to contain high concentrations of novel intracellular solutes such as beta-mannosylglycerate and di-myo-inositol 1,1'-phosphate (DIP) (L. O. Martins and H. Santos, Appl. Environ. Microbiol. 61:3299-3303, 1995). Here, 31P nuclear magnetic resonance (NMR) spectroscopy was used to show that this organism also accumulates another type of phospho compound, as revealed by a major multiplet signal in the pyrophosphate region. The compounds were purified from cell extracts of P. furiosus by anion-exchange and gel filtration chromatographic procedures and were structurally analyzed by 1H, 13C, and 31P NMR spectroscopy. They were identified as two uridylated amino sugars, UDP N-acetylglucosamine and UDP N-acetylgalactosamine. Unambiguous characterizations and complete assignments of 1H and 13C resonances from such sugars have not been previously reported. In vitro 31P NMR spectroscopic analyses showed that, in contrast to DIP, which is maintained at a constant intracellular concentration (approximately 32 mM) throughout the growth phase of P. furiosus, the UDP amino sugars accumulated (to approximately 14 mM) only during the late log phase. The possible biochemical roles of these compounds in P. furiosus are discussed.

Archaea↗
PubMed1996

2D 1H and 3D 1H-15N NMR of zinc-rubredoxins: contributions of the beta-sheet to thermostability.

Based on 2D 1H-1H and 2D and 3D 1H-15N NMR spectroscopies, complete 1H NMR assignments are reported for zinc-containing Clostridium pasteurianum rubredoxin (Cp ZnRd). Complete 1H NMR assignments are also reported for a mutated Cp ZnRd, in which residues near the N-terminus, namely, Met 1, Lys 2, and Pro 15, have been changed to their counterparts, (-), Ala and Glu, respectively, in rubredoxin from the hyperthermophilic archaeon, Pyrococcus furiosus (Pf Rd). The secondary structure of both wild-type and mutated Cp ZnRds, as determined by NMR methods, is essentially the same. However, the NMR data indicate an extension of the three-stranded beta-sheet in the mutated Cp ZnRd to include the N-terminal Ala residue and Glu 15, as occurs in Pf Rd. The mutated Cp Rd also shows more intense NOE cross peaks, indicating stronger interactions between the strands of the beta-sheet and, in fact, throughout the mutated Rd. However, these stronger interactions do not lead to any significant increase in thermostability, and both the mutated and wild-type Cp Rds are much less thermostable than Pf Rd. These correlations strongly suggest that, contrary to a previous proposal [Blake PR et al., 1992, Protein Sci 1:1508-1521], the thermostabilization mechanism of Pf Rd is not dominated by a unique set of hydrogen bonds or electrostatic interactions involving the N-terminal strand of the beta-sheet. The NMR results also suggest that an overall tighter protein structure does not necessarily lead to increased thermostability.

Amino Acid Sequence↗
PubMed1996

[Study on the level of soluble interleukin-2 receptor, expression of membrane interleukin-2 receptor and T lymphocyte subpopulations in pulmonary tuberculosis].

OBJECTIVE: To evaluate the significance of soluble interleukin-2 receptor (sIL-2R), membrane interleukin-2 receptor (mIL-2R) and T lymphocyte subpopulations in development of pulmonary tuberculosis. METHODS: The level of sIL-2R, expression of mIL-2R and the profile of T lymphocyte subpopulations in patients with pulmonary tuberculosis were tested by sandwiched ELISA and alkaline phosphatase-antialkaline phosphate (APAAP) methods. RESULTS: The levels of sIL-2R, CD8 were higher, and expression of mIL-2R, CD4, CD4/CD8 ratio were lower in pulmonary tuberculosis than those in normal controls (P < 0.001). And the changes of all indicators in patients with cavitation were more obvious than those in patients without (P < 0.001), the changes in progressive stage were more obvious than those in stable and improving stages (P < 0.001). CONCLUSION: The results indicated that the patients, condition and prognosis of pulmonary tuberculosis were related to the changes of sIL-2R level, mIL-2R expression and T lymphocyte subpopulations.

Adult↗
PubMed1995

1H NMR investigation of the electronic and molecular structure of the four-iron cluster ferredoxin from the hyperthermophile Pyrococcus furiosus. Identification of Asp 14 as a cluster ligand in each of the four redox states.

The molecular and electronic structure of the four-iron cluster of the ferredoxin (Fd) from the hyperthermophilic archaeon, Pyrococcus furiosus, Pf (which has only three Cys in the cluster binding consensus sequence), has been investigated by 1H NMR in order to determine the identity of the noncysteinyl cluster ligand in each of the four redox states [Gorst, C. M., Zhou, Z. H., Ma, K., Teng, Q., Howard, J. B., Adams, M. W., & La Mar, G. N. (1995) Biochemistry 34, 8788-8795], and to characterize the electron spin ground state for the reduced cluster which at 10 K exhibits an unusual predominant S = 3/2 ground state [Conover, R. C., Kowal, A. T., Fu, W., Park, J. -B., Aono, S., Adams, M. W. W., & Johnson, M. K. (1990) J. Biol. Chem. 265, 8533-8541]. It is demonstrated that a combination of 1D and 2D NMR tailored to relaxed resonances allows the location of four hyperfine shifted and paramagnetically relaxed spin systems which dictates that all four cluster ligands are amino acid side chains, rather than a solvent water/hydroxide at the unique non-Cys ligation site. Three of the ligands could be sequence-specifically assigned to the three Cys residues (positions 11, 17, and 56) in the consensus sequence for cluster binding, hence identifying the fourth ligand as Asp 14. It is concluded that the identification of Asp ligation to a 4Fe cluster is readily achieved in the reduced, but not in the oxidized cluster of Fd. Analysis of the relaxation properties and pattern of the hyperfine shifts in Pf Fd reveals very strong similarities to other Fds with S = 1/2 ground states, leading to the conclusion that the S = 3/2 ground state is not detected in solution at ambient temperatures, and this in independent of the redox state of the two remaining Cys residues in the protein (positions 21 and 48). However, the electron self-exchange rate for 4Fe Pf Fd is significantly slower than for other 4Fe Fd with complete Cys ligation. Changes in the pattern of hyperfine shifts between oxidized and reduced clusters for the four ligands in Pf Fd reveal that the most significant variation occurs for the Asp 14 orientation, suggesting that the altered Asp orientation may "gate" the electron transfer.

Archaea↗
PubMed1995

Participation of the disulfide bridge in the redox cycle of the ferredoxin from the hyperthermophile Pyrococcus furiosus: 1H nuclear magnetic resonance time resolution of the four redox states at ambient temperature.

The oxidized and reduced forms of the [4Fe-4S]-containing ferredoxin from the hyperthermophilic archaeon Pyrococcus furiosus, Pf, have been investigated by 1H nuclear magnetic resonance spectroscopy, electron paramagnetic resonance spectroscopy and thiol titrations. We have identified and isolated at Ambient temperature four distinct redox states for the [4Fe-4S] form of the ferredoxin. These states differ in the redox state of the cluster, which is coordinated by Cys 11, Asp 14, Cys 17, and Cys 56, and of a disulfide bridge between Cys 21 and Cys 48. The protein, as isolated under anaerobic conditions, designated 4Fe FdBred, contains the reduced cluster and two free thiols. The cluster, but not the thiols, is readily oxidized by brief exposure to O2 to yield 4Fe FdBOX. Prolonged O2 treatment (> 24 h at 30 degrees C) is required to generate the protein with a disulfide (4Fe FdAOX) while this fully oxidized form is readily converted by brief reduction with sodium dithionite to the protein with a reduced cluster and a disulfide (4Fe FdAred). Analyses of the magnitude and the number of hyperfine-shifted resonances in each of the four redox states are discussed.

Archaea↗
PubMed1995

1H NMR investigation of the paramagnetic cluster environment in Pyrococcus furiosus three-iron ferredoxin: sequence-specific assignment of ligated cysteines independent of tertiary structure.

One- and two-dimensional 1H NMR data tailored to detect paramagnetically relaxed protons near the S = 1/2, three-iron-sulfur cluster of the ferredoxin from the hyperthermophile Pyrococcus furiosus are analyzed to sequence specifically assign the hyperfine shifted ligated cysteine signals, to determine the nature of the secondary structural elements on which these cysteines reside, and to define the tertiary contacts of the cluster with the remainder of the previously characterized secondary structure remote from the cluster [Teng, Q., Zhou, Z.-H., Busse, S.C., Howard, J.B., Adams, M. W. W., & La Mar, G. N. (1994) Biochemistry 33, 6316-6326]. Inspection of the geometry of the cluster ligating cysteines in the six structurally characterized cubane ferredoxin (Fd) clusters reveals a pattern of distances from the cluster iron(s) that indicate that each Cys will exhibit one backbone proton that will allow the detection of dipolar connectivities to the backbone of adjacent residues. It is expected that the first and last of the Cys in the cluster consensus binding sequence will exhibit weakly relaxed peptide NH and strongly relaxed C alpha H signals, while the two central Cys in that sequence will exhibit strongly relaxed peptide NH but weakly relaxed C alpha H peaks. These dipolar contacts are clearly observed for the three ligated Cys in 3Fe P. furiosus Fd, providing the first sequence specific assignment of ligated cysteines which do not explicitly require knowledge of the tertiary structure of the protein. This approach is proposed to have very general application to cubane ferredoxins. A combination of steady-state NOEs and short mixing time NOESY experiments demonstrate that Cys17 is on a short helix through Leu20 and that Cys56 likely initiates a type I turn, as observed in the crystal structure of the 3Fe Fd for Desulfovibrio gigas [Kissinger, C. R., Sieker, L. C., Adman, E. T., & Jensen, L. H. (1991) J. Mol. Biol. 219, 693-715]. The observed relaxation rates of resolved or partially resolved signals are shown to correlate with their proximity to the various iron in the cluster, as determined for the homologous residues in D. gigas Fd, providing additional qualitative information on tertiary contacts of the cluster.

Amino Acid Sequence↗
PubMed1995

Experimental study of fat embolism syndrome.

To find the diagnostic methods for subclinical stage fat embolism syndrome (FES), we established an experimental animal model, using fat intravenous injection. The fat was obtained from the long bone marrow cavity of homologous dogs. Fourteen healthy mongrel dogs received 0.7 ml/kg fluid marrow fat injection and all of them developed FES within 48 hours. The blood samples collected from the pulmonary vessels by floating catheter and peripheral vein at different time intervals were subjected to blood gas analysis and were frozen sectioned rapidly. The sections were stained with oil red 'O'. Positive result was seen 2 hours after fat injection in both pulmonary and peripheral blood. Computer image analysis showed that the number and diameter of fat droplets in pulmonary vascular blood were obviously higher and larger than those in peripheral vein blood. These findings were correlated well with blood gas changes and clinical features. The demonstration of fat droplets from pulmonary or peripheral blood by oil red 'O' staining combined with blood gas changes (PaO2 < 7.99 kPa, P(A-a)O2 > 6.09 kPa) may be rapid and specific for early diagnosis of FES. In the treatment of FES, dexamethason can stabilize the cellular membranes and inhibit the neutrophil response to fatty acid and the release of phospholipase A2, arachidonic acid and platelet aggregation.

Animals↗