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J Deng

Publications and source records attributed to J Deng.

At least 55 records · Page 3Linked to original sources
PubMed2001

Crystal structures of two forms of a 14-mer RNA/DNA chimer duplex with double UU bulges: a novel intramolecular U*(A x U) base triple.

The RNA/DNA 14-mer, (gguauuucgguaCc)2 with consecutive uridine bulges (underlined) on each strand has been determined in two crystal forms, spermine bound (Sp-form) and spermine free (Sp-free). The former was solved by the MAD method with three-wavelength data collected at Brookhaven National Laboratory (BNL); the later isomorphous structure was solved by the molecular replacement method using data collected on our Raxis IIc imaging plate system. The two crystal forms belong to the space group C2 with one molecule of double-stranded 14 mer in the asymmetric unit. The Sp-form has cell constants, a = 60.06, b = 29.10, c = 52.57 A, beta = 120.79 degrees and was refined to 1.7 A resolution with a final Rwork/Rfree of 19.8%/22.7% using 8,549 independent reflections. The Sp-free structure has cell constants, a = 60.06, b = 29.58, c = 52.50 A, beta = 120.85 degrees and was refined to 1.8 A with a final Rwork/ Rfree of 20.8%/23.2% using 6,285 unique reflections. The two structures are identical, except that the Sp-form has a spermine bound in the major groove, parallel to the RNA helical axis. One of the uridine bulges forms a novel intramolecular U*(A x U) base triple. The helices are in the C3'-endo conformation (A-form), but the bulges adopt the C2'-endo sugar pucker. Furthermore, the bulges induce a kink (30 degrees) in the helix axis and a very large twist (55 degrees) between the base pairs flanking the bulges. The Sp-form has one Mg2+ ion whereas the Sp-free form has two Mg2+ ions.

Chimera↗
PubMed2001

[The paraoxonase Gln-Arg192 polymorphism in patients with coronary heart disease in Chinese population].

OBJECTIVE: To investigate the 192 Gln-Arg polymorphism of paraoxonase (PON) gene and its relationship with serum lipids levels in patients with coronary heart disease in Chinese population. METHODS: The genotype and allele frequency of paraoxonase gene 192 Gln-Arg polymorphism was assayed by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). Serum lipids were measured by enzymatic kits in 118 CHD patients and 128 healthy subjects whose fasting serum TG levels were < 1.82 mmol/L and TC levels < 6.2 mmol/L from a population of Chinese Han nationality in Chengdu area. RESULTS: Both in CHD group and control group, the QR genotype of PON gene was the major one, and its frequencies were 0.578 and 0.525 respectively. No differences were found in PON gene Gln-Arg polymophism in the CHD group when compared with the control group. The frequency of R allele of PON gene in Chinese was significant higher than that in European and American Caucasians (0.51 vs. 0.26-0.31, P < 0.01) and Indian (0.51 vs. 0.17, P < 0.01), and significantly lower than that in Japanese (0.51 vs. 0.65, P < 0.01). CONCLUSION: These results suggested that the Gln-Arg192 polymorphism of the PON1 gene was not associated with coronary heart disease in Chinese population.

Aged↗
PubMed2001

[Correlation of tumor microvessel density with prognosis in laryngopharyngeal malignant melanoma].

OBJECTIVE: To investigate the relationship between microvessel density and clinicopathology, as well as the prognosis in pharyngo-laryngeal malignant melanoma. METHODS: Specific endothelial cell markers with immunohistochemistry and microvessel density with morphometry in 28 cases of laryngopharyngeal malignant melanoma. RESULTS: There was no correlation between the microvessel density (MVD) and the tumor size, Clark grade, as well as Breslow grade; however, significant correlation was found between the MVD and the AJC's grade, as well as the proliferating cell nuclear antigen (PCNA) labelling index. Microvessel counts were associated with overall survival by Kaplan-Meier analysis. An average vessel count of less than 36.5 (x 200) suggested a better survival, but a higher vessel count of more than 36.5 (x 200) showed a trend to worse the overall survival. CONCLUSION: The results suggest a significant relationship between MVD and prognosis; moreover, MVD may be a useful prognostic indicator in laryngopharyngeal malignant melanoma.

Adult↗
PubMed2000

Synthesis and crystal structure of an octamer RNA r(guguuuac)/r(guaggcac) with G.G/U.U tandem wobble base pairs: comparison with other tandem G.U pairs.

We have determined the crystal structure of the RNA octamer duplex r(guguuuac)/r(guaggcac) with a tandem wobble pair, G.G/U.U (motif III), to compare it with U.G/G.U (motif I) and G.U/U.G (motif II) and to better understand their relative stabilities. The crystal belongs to the rhombohedral space group R3. The hexagonal unit cell dimensions are a = b = 41.92 A, c = 56.41 A, and gamma = 120 degrees, with one duplex in the asymmetric unit. The structure was solved by the molecular replacement method at 1.9 A resolution and refined to a final R: factor of 19.9% and R(free) of 23.3% for 2862 reflections in the resolution range 10.0-1.9 A with F >/= 2sigma(F). The final model contains 335 atoms for the RNA duplex and 30 water molecules. The A-RNA stacks in the familiar head-to-tail fashion forming a pseudo-continuous helix. The uridine bases of the tandem U.G pairs have slipped towards the minor groove relative to the guanine bases and the uridine O2 atoms form bifurcated hydrogen bonds with the N1 and N2 of guanines. The N2 of guanine and O2 of uridine do not bridge the 'locked' water molecule in the minor groove, as in motifs I and II, but are bridged by water molecules in the major groove. A comparison of base stacking stabilities of motif III with motifs I and II confirms the result of thermodynamic studies, motif I > motif III > motif II.

Base Pairing↗
PubMed2000

Allergen-induced airway hyperreactivity is diminished in CD81-deficient mice.

We demonstrated previously that CD81(-/-) mice have an impaired Th2 response. To determine whether this impairment affected allergen-induced airway hyperreactivity (AHR), CD81(-/-) BALB/c mice and CD81(+/+) littermates were sensitized i.p. and challenged intranasally with OVA. Although wild type developed severe AHR, CD81(-/-) mice showed normal airway reactivity and reduced airway inflammation. Nevertheless, OVA-specific T cell proliferation was similar in both groups of mice. Analysis of cytokines secreted by the responding CD81(-/-) T cells, particularly those derived from peribronchial draining lymph nodes, revealed a dramatic reduction in IL-4, IL-5, and IL-13 synthesis. The decrease in cytokine production was not due to an intrinsic T cell deficiency because naive CD81(-/-) T cells responded to polyclonal Th1 and Th2 stimulation with normal proliferation and cytokine production. Moreover, there was an increase in T cells and a decrease in B cells in peribronchial lymph nodes and in spleens of immunized CD81(-/-) mice compared with wild-type animals. Interestingly, OVA-specific Ig levels, including IgE, were similar in CD81(-/-) and CD81(+/+) mice. Thus, CD81 plays a role in the development of AHR not by influencing Ag-specific IgE production but by regulating local cytokine production.

Administration, Intranasal↗
PubMed2000

Distinct distribution of rare us kshv genotypes in south texas. Implications for kshv epidemiology and evolution.

PURPOSE: Kaposi's sarcoma-associated herpesvirus (KSHV, or human herpesvirus 8) is etiologically associated with Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL). Although previous studies have assessed the geographic distribution of KSHV genotypes, the molecular epidemiology of KSHV remains largely unknown. The purpose of the present study was to examine the genotypes of KSHV isolates from KS patients in South Texas.METHODS: Eighteen KSHV isolates from 16 KS and 1 PEL patients in South Texas were collected between 1996 and 1998 and analyzed for KSHV subtypes by PCR sequencing of ORFK1 gene and KS330 fragment, and by PCR of ORFK15 gene. DNA sequences were aligned with known sequences and KSHV subtypes were assigned based on sequence variations.RESULTS: Of 18 KSHV isolates, 13 exhibited C subtype, and 5 exhibited A subtype in ORF K1 gene. ORF K15 genotyping showed that 10 of the isolates exhibited M form, of which 9 had C3 subtype. A unique C subtype isolate was found and classified as C6 clade. All of the M form KSHV isolates were found among KS patients over 50 years of age. Conversely, all KS patients under 40 years of age had only the P form KSHV isolates.CONCLUSIONS: In South Texas there is a distinct distribution of C3/M KSHV isolates, which are rarely found in other US regions (1 of 29). The C3/M KSHV genotype is more prevalent in HIV-negative elderly KS patients while the P-form of KSHV is more common among many young AIDS-KS patients.

Journal Article↗
PubMed2000

Probing trace phenols based on mediator-free alumina sol--gel-derived tyrosinase biosensor.

A novel tyrosinase biosensor has been developed for the subnanomolar detection of phenols, based on the immobilization of tyrosinase in a positively charged Al2O3 sol-gel membrane on a glassy carbon electrode. It has been found that Al2O3 sol-gel is perfectly beneficial to the immobilization of tyrosinase, because it not only possesses the general advantages of sol-gel but it also is an effective promoter of the biosensor. The large microscopic surface area, porous morphology, and hydrophilic property of the sol-gel matrix result in high enzyme loading, and the enzyme entrapped in this matrix retains its activity to a large extent. The Al2O3 sol-gel-containing surface also displays an intrinsic electrocatalytic o-quinone response and, hence, offers a high-sensitivity (127 microA mM(-1)) monitoring of phenols. The detection limit is 0.2 nM at a signal-to-noise ratio of 3, the response time is less than 4 s reaching 95% of the steady-state value, and 70% of the activity is retained after 3 months.

Biosensing Techniques↗
PubMed2000

Polymorphic CAG and GGN repeat lengths in the androgen receptor gene and prostate cancer risk: a population-based case-control study in China.

The length of the polymorphic CAG trinucleotide repeat in the polyglutamine region of the androgen receptor (AR) gene is inversely correlated with the transactivation function of the AR. Because increased androgenic activity has been linked to prostate cancer and because an ethnic variation exists in the CAG repeat length, this polymorphism has been suggested to explain part of the substantial racial difference in prostate cancer risk. We conducted a population-based case-control study in China to investigate whether CAG and other polymorphisms of the AR gene are associated with clinically significant prostate cancer in this low-risk population. Genomic DNA from 190 prostate cancer patients and 304 healthy controls was used for direct sequencing to evaluate the relationship of CAG and GGN (polyglycine) repeat length in the AR gene. Relative to western men, our study subjects had a longer CAG repeat length, with a median of 23 and only 10% of the subjects having a CAG repeat length shorter than 20. Men with a CAG repeat length shorter than 23 (median length) had a 65% increased risk of prostate cancer (odds ratio, 1.65; 95% confidence interval, 1.14-2.39), compared with men with a CAG repeat length of 23 or longer. For the GGN tract (GGT3GGG1GGT2GGCn), based on the sequencing results from 481 samples, we are the first to show that although GGC regions in the polyglycine tract are highly variable, there are no mutations or polymorphisms in the GGT and GGG regions. More than 72% of the subjects had a GGN repeat length of 23, and those with a GGN repeat length shorter than 23 had a 12% increased risk of prostate cancer (95% confidence interval, 0.71-1.78), compared with those with > or = 23 GGN repeats. Our study not only confirms that Chinese men do have a longer CAG repeat length than western men but also represents the first population-based study to show that even in a very low-risk population, a shorter CAG repeat length confers a higher risk of clinically significant prostate cancer. These results imply that CAG repeat length can potentially serve as a useful marker to identify a subset of individuals at higher risk of developing clinically significant prostate cancer. Larger studies are needed to evaluate the combined effect of CAG and GGN repeats. Because of the significance of AR in prostate cancer, investigation of factors that interact with the polyglutamine region of the AR gene to alter AR function and modulate prostate cancer risk is an important area for future research.

Aged↗
PubMed2000

Novel technique for three-dimensional visualisation and quantification of deformable, moving soft-tissue body parts.

BACKGROUND: Three-dimensional (3D) imaging of delicate, moving soft-tissue body parts is very difficult. Our understanding of the muscles that control lip movements is based largely on histological and cadaveric studies, which provide scant information about dynamic morphology. Our aim was to develop an innovative scanning technique for the imaging and reconstruction of dynamic orofacial morphology by use of 3D and four-dimensional (4D, ie, 3D plus time) ultrasonography. METHODS: Four volunteers (including one patient) underwent ultrasonography with 3D/4D imaging systems. To avoid deformation of the delicate orofacial structures, a water bath with an acoustic window was devised. The orofacial part was immersed in the bath throughout scanning, and a timer was used to synchronize lip movements with the 4D scan. FINDINGS: 4D views showed the functional differences in superficial and deep muscle groups of the lips, and clearly showed the changes occurring with movement of the lips and mouth. In the patient, a pathological layer and its extension corresponding to surface malformation were clearly identified. INTERPRETATION: We have developed a prototype device that has made possible 3D and 4D examination of orofacial anatomy and function. With further refinement of the device and improvement in 4D acquisition timing, this technique may offer a new way of dynamically imaging and quantifying many soft-tissue parts in 3D without deforming structure or disturbing function.

Adult↗
PubMed2000

Distinct roles for amino- and carboxyl-terminal sequences of SPRR1 protein in the formation of cross-linked envelopes of conducting airway epithelial cells.

The small proline-rich protein, SPRR1, is a marker gene whose expression in conducting airway epithelium is elevated under a variety of conditions that enhance squamous differentiation. The purpose of this study is to elucidate the nature of the SPRR1 sequence involved in cross-linked envelope formation in a tissue/cell type, such as conducting airway epithelium, that normally does not express squamous function except after injury or maintenance in culture. For this, a Flag-SPRR1 fusion protein expression system has been developed. Using the liposome-mediated gene transfer technique on passage 1 culture of human tracheobronchial epithelial (TBE) cells, the Flag-SPRR1 fusion protein can be expressed and detected immunologically by both anti-Flag and anti-SPRR1 antibodies. The incorporation of Flag-SPRR1 fusion protein into cross-linked envelopes can be demonstrated when transfected human passage 1 TBE cultures are treated with phorbol 12-myristate 13-acetate and high calcium (1.5 mM). By deletion and site-directed mutagenesis, two distinct roles of the amino- and carboxyl-terminal sequences of SPRR1 have been demonstrated. First, we demonstrated that the amino-terminal sequence of SPRR1 protein is required for the incorporation of the fusion protein into cross-linked envelopes, whereas a deletion on the carboxyl-terminal region or on the middle repetitive unit has no effect. Interestingly, insertion of a 24-amino acid peptide of monkey MUC2 repetitive sequence in the amino-terminus of SPRR1 protein had a stimulatory effect. Site-directed mutagenesis on the following amino acid residues, Lys(7), Gln(88), and Lys(89), which were found previously to participate in the cross-linked envelope formation of keratinocytes, had no detrimental effect on the incorporation. However, mutations on Gln clusters, such as Gln(4)-Gln(6) and Gln(22)-Gln(25), had detrimental effects on the incorporation. These results suggest an amino-terminal sequence-dependent and multiple cross-linked sites for the incorporation of Flag-SPRR1 fusion protein into cross-linked envelopes of cultured human TBE cells. Second, we demonstrated that the carboxyl terminus of SPRR1 protein is required for a high level of Flag-fusion protein expression. A deletion in the carboxyl region or a mutation on the last lysine residue of the carboxyl end had a detrimental effect on the level of Flag-SPRR1 fusion protein expressed in transfected cells. In contrast, there was only a slight decrease in the level of expression if the amino-terminus was deleted. Interestingly, the efficiency for fusion protein to incorporate into cross-linked envelopes was elevated by the mutation at the carboxyl end. These results suggest distinct roles, perhaps coordinately, for both amino- and carboxyl-terminal sequences in the regulation of the life cycle of SPRR1 protein in cultured TBE cells.

Amino Acid Sequence↗
PubMed2000

Dominant sensitization variants of human O(6)-methylguanine-DNA-methyltransferase obtained by a mutational screen of surface residues.

A scanning mutagenesis experiment was performed on human O(6)-methylguanine methyltransferase (hMGMT), directed largely at non-conserved surface residues that have not previously been studied. Variants typically contained two or more substitutions. Two of the 16 variants characterized in detail are inactive for methyltransfer, but increase the cytotoxicity and mutagenic effects of methylating agents. This phenotype is reminiscent of a variant (C145A) that has a mutation in the methyl-accepting cysteine. C145A is inactive, but reportedly binds methylated DNA and confers sensitivity to methylating agents. The sensitization phenotype of the two new variants is more striking in strains that are wild-type for DNA repair than in strains that are deficient for repair, suggesting that these proteins inhibit functional DNA repair proteins by competitively binding to methylated DNA. Both variants have multiple substitutions in the last helix of the protein. These results suggest that the C-terminal helix is necessary for methyltransfer activity, but not for methylguanine-specific binding.

Amino Acid Sequence↗
PubMed2000

Interleukin-4 mediates STAT6 activation in 3T3-L1 preadipocytes but not adipocytes.

STAT6 is abundantly expressed in 3T3-L1 preadipocytes and adipocytes but activating ligands are not well defined. In this report, we provide evidence that interleukin 4 (IL-4) induced JAK2-mediated STAT6 tyrosine phosphorylation and DNA binding in 3T3-L1 preadipocytes but not in 3T3-L1 adipocytes. Loss of IL-4-mediated STAT6 tyrosine phosphorylation occurred 2 days after preadipocytes were induced to differentiate into adipocytes but when cells remained phenotypically preadipocytes. 3T3-L1 adipocytes were still responsive to IL-4 through tyrosine phosphorylation of other cellular proteins. We conclude that IL-4 signals through STAT6 in 3T3-L1 preadipocytes but not in 3T3-L1 adipocytes. This differentiation-dependent loss of STAT6 activation may be critical for distinct biological effects of IL-4 in 3T3-L1 preadipocytes and adipocytes.

3T3 Cells↗
PubMed2000

Tumor suppression and sensitization to tumor necrosis factor alpha-induced apoptosis by an interferon-inducible protein, p202, in breast cancer cells.

p202, an IFN-inducible protein, interacts with several important regulatory proteins, leading to growth arrest or differentiation. In this report, we demonstrate that, in addition to inhibiting in vitro cell growth, p202 can also suppress the tumorigenicity of breast cancer cells in vivo. Furthermore, we found that p202 expression could sensitize breast cancer cells to apoptosis induced by tumor necrosis factor alpha treatment. One possible mechanism contributing to this sensitization is the inactivation of nuclear factor-kappaB by its interaction with p202. These results provide a scientific basis for a novel therapeutic strategy that combines p202 and tumor necrosis factor alpha treatment against breast cancer.

Apoptosis↗
PubMed2000

An amperometric biosensor based on the coimmobilization of horseradish peroxidase and methylene blue on a beta-type zeolite modified electrode.

A new biosensor for the amperometric detection of hydrogen peroxide was developed based on the coimmobilization of horseradish peroxidase (HRP) and methylene blue on a beta-type zeolite modified glassy carbon electrode without the commonly used bovine serum albumin-glutaraldehyde. The intermolecular interaction between enzyme and zeolite matrix was investigated using FT-IR. The cyclic voltammetry and amperometric measurement demonstrated that methylene blue co-immobilized with HRP in this way displayed good stability and could efficiently transfer electrons between immobilized HRP and the electrode. The sensor responded rapidly to H2O2 in the linear range from 2.5 x 10(-6) to 4.0 x 10(-3) M with a detection limit of 0.3 microM. The sensor was stable in continuous operation.

Biosensing Techniques↗
PubMed2000

Spectroelectrochemical investigation of direct electron transfer between resting horseradish peroxidase and its oxidation states promoted by DNA.

Direct electron transfer between resting horseradish peroxidase (HRP) and its oxidation states was observed at a gold mesh electrode in a spectroelectrochemical cell in the presence of DNA. The conversion between HRP and the oxidized species induced electrochemically was found to be reversible and parallel to that initiated chemically. DNA played an important role as electron carrier and promoted the electron transfer between HRP and the electrodes. Voltammetric results and CD spectra indicated an interaction between HRP and DNA. Moreover, the secondary structure of HRP was slightly disturbed upon mixing with DNA. The direct spectroelectrochemistry of HRP at a gold mesh electrode presented new information on its bioelectrochemical characteristics.

Circular Dichroism↗
PubMed2000

Simultaneous use of two ultrasound scanners for motion-gated three-dimensional fetal echocardiography.

The aim of this study was to determine whether or not simultaneous use of an additional Doppler transducer could provide sufficient cardiovascular motion information without significantly interfering with three-dimensional (3-D) cardiac structural data acquisition by a primary two-dimensional (2-D) transducer. To determine sources of interference, paired transducers were activated alternatively and simultaneously in and out of a water bath, with and without electrical insulating and electromagnetic shielding. To determine factors affecting interference, pairs were tested on a phantom with different separating distances and angles between paired ultrasound (US) beams and under different 2-D depths and Doppler scales. Results show that the dominant source of interference is acoustic cross talk. The severity was mainly affected by transducer pairing and by separating distances and angles, and the pattern by display settings. With optimised settings, sufficient structural and motion data were obtained simultaneously in 9 of 12 fetal hearts, and detailed 3-D views could be reconstructed free of motion artefacts, confirming the feasibility of using the method for motion-gated 3-D fetal cardiac imaging. New scanner design strategy was then proposed.

Artifacts↗
PubMed2000

Structural analysis of transition metal beta-X substituent interactions. Toward the use of soft computing methods for catalyst modeling

Fuzzy logic and neural network techniques are used to classify intramolecular interactions between transition metals (M) and beta-X substituents in the following structural motif (LnMC(alpha)(A1)(A2)-C(beta)(B1)(B2)X). These interactions are relevant to the direct polymerization of functionalized olefins by Ziegler-Natta (ZN) catalysis. The efficiency and effectiveness of different soft computing techniques are compared. These methods give not only encouraging results with respect to general data mining issues but also insight into the factors that effect interactions between transition metals and beta-X substituents.

Journal Article↗