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Biomedical subjects

Q Hao

Publications and source records attributed to Q Hao.

At least 19 recordsLinked to original sources
PubMed2006

Variables which might predict the response to salvage radiotherapy in chinese patients with biochemical failure after radical prostatectomy.

BACKGROUND/AIMS: To evaluate the relationship between the variables and the outcomes of salvage radiotherapy (sRT) to find some predictors of sRT. METHODS: The medical records of 56 patients receiving sRT for biochemical failure after radical prostatectomy (RP) were available for retrospective review. sRT was defined as external beam radiotherapy for patients with a continuous increase in the prostate-specific antigen (PSA) level of >or=0.2 ng/ml after RP. Response was defined as achievement of a PSA nadir of 6 months were all responders. The response rate in patients with seminal vesicle invasion was 42.9% (6/14) versus 76.2% (32/42) in patients without seminal vesicle invasion (OR=0.119, p=0.015). CONCLUSION: PSADT and the state of seminal vesicle invasion were good predictors of response to sRT. sRT was especially effective when the PSADT was >6 months and in patients without seminal vesicle invasion.

China↗
PubMed2005

Domain-specific fluorescence resonance energy transfer (FRET) sensors of metallothionein/thionein.

Each of the two domains of mammalian metallothioneins contains a zinc-thiolate cluster. Employing site-directed mutagenesis and chemical modification, fluorescent probes were introduced into human metallothionein (isoform 2) with minimal perturbations of the structures of these clusters. The resulting FRET (fluorescence resonance energy transfer) sensors are specific for each domain. The design and construction of a sensor for the alpha-domain cluster is based on a FRET pair where a C-terminally added tryptophan serves as the donor for a fluorescence acceptor attached to a free cysteine in the linker region between the two domains. Molecular modeling studies and steady-state fluorescence polarization anisotropy measurements suggest unrestricted motion of the tryptophan donor, but limited motion of the AEDANS ([[(amino)ethyl]amino]naphthalene-1-sulfonic acid) acceptor, putting constraints on the use of the alpha-domain sensor with this FRET pair as a spectroscopic ruler. The fluorescent metallothioneins allow distance measurements during binding and removal of metals in the individual domains. The overall dimensions of the apoprotein, thionein, for which no structural information is available, do not seem to be significantly different from those of the holoprotein. The single- and double-labeled fluorescent metallothioneins overcome a longstanding impediment in studies of the function of this protein, namely its lack of intrinsic probe characteristics.

Biosensing Techniques↗
PubMed2004

SAD phasing by combination of direct methods with the SOLVE/RESOLVE procedure.

In the initial stage of SAD phasing, the essential point is to break the intrinsic phase ambiguity. The presence of two kinds of phase information enables the discrimination of phase doublets from SAD data prior to density modification. One is from the heavy atoms (anomalous scatterers), while the other is from the direct-methods phase relationships. The former can be expressed by the Sim distribution, while the latter can be expressed by the Cochran distribution. Typically, only the Sim distribution has been used to yield initial phases for subsequent density modification. However, it has been demonstrated that using direct-methods phases based on the product of the Sim and Cochran distributions can lead to improved initial phases. In this paper, the direct-methods phasing procedure OASIS has been improved and combined with the SOLVE/RESOLVE procedure. Experimental SAD data from three known proteins with expected Bijvoet ratios / in the range 1.4-7.0% were used as test cases. In all cases, the phases obtained using the program RESOLVE beginning with initial phases based on experimental phases plus Sim and direct-methods information were more accurate than those based on experimental plus Sim phase information alone.

Azurin↗
PubMed2004

Synergistic anti-tumor effect of ultrasound and hematoporphyrin on sarcoma180 cells with special reference to the changes of morphology and cytochrome oxidase activity of tumor cells.

This study is aimed at evaluating the inhibitory effects of the association of hematoporphyrin and ultrasound at variable intensities with a fixed frequency of 1.1MHz in tumor nodules. Specifically, the effects were studied both in solid and ascitic S180 tumors transplanted in mice by clinical, cytochemical and ultrastructural evaluation. The results indicated that the use of hematoporphyrin alone had no significant effect on destroying tumor cells. The ultrasound alone had little effect. Interestingly, the inhibition was much more effective when hematoporphyrin was combined with ultrasound. The inhibition was 3 times better than ultrasound alone and 8 times better than hematoporphyrin used alone. Our results also indicated that the changes on cell structure and cytochrome oxidation activity are important factors that could inhibit tumor cell growth and induce cell death. Apoptosis of tumor cells could be induced by hematoporphyrin. Our study investigated the killing mechanism on S180 tumor cells by using hematoporphyrin and low frequency ultrasound at cell, tissue and individual level.

Animals↗
PubMed2003

Crystallization and preliminary crystallographic analysis of a new class of glutathione transferase from nematodes.

Mouse and Heligmosomoides polygyrus constitute a readily manipulated small-animal laboratory model for investigating host-nematode interactions. Two major forms of glutathione transferase (GST) are expressed in H. polygyrus adult worms following primary infection. One of these forms belongs to a new class of GST which has only been found in the nematode phylum and therefore presents a possible target for nematode control. In this study, crystals were obtained of a recombinant representative of this new GST class from H. polygyrus. These crystals belong to the triclinic space group P1, with unit-cell parameters a = 72.7, b = 74.0, c = 88.6 A, alpha = 79.1, beta = 80.1, gamma = 81.5 degrees, and are likely to contain four homodimers in the asymmetric unit. X-ray diffraction data were collected to 1.8 A resolution on station A1 at the Cornell High-Energy Synchrotron Source (CHESS).

Animals↗
PubMed2002

Chlamydia pneumoniae infection associated with enhanced MRI spinal lesions in multiple sclerosis.

Cerebrospinal fluid (CSF) from 66 patients with multiple sclerosis (MS) and 25 patients with other neurological diseases (OND) were examined for the infection of Chlamydia pneumoniae by culture, polymerase chain reaction (PCR) assay, and determination of antibodies to C. pneumoniae. PCR was positive not only in 9 of 28 (32%) patients with MS but also in 2 patents with inflammatory disorders in 15 (13%) OND controls (p = 0.18). Viable C. pneumoniae was isolated from one patient with MS and one with paraneoplastic encephalomyelitis. C. pneumoniae could be detected only in cell-containing CSF. In MS, enhanced spinal magnetic resonance imaging (MRI) lesions were detected in all of four PCR-positive patents but none of five PCR-negative patients, and the difference was significant (p = 0.0079). However, no correlation was found between enhanced brain MRI lesions and CSF C. pneumoniae DNA. Elevated titers of anti-C. pneumoniae IgG were detected in CSF in 13 of 66 (20%) patients with MS and 1 of 25 (4%) OND controls (p = 0.064). CNS C. pneumoniae infection is not uncommon in MS as well as in other inflammatory disorders of the nervous system. The association of active spinal lesions with Chlamydia in CSF collected by lumber puncture suggests the detection of a recent infection. On the other hand, the lack of association of active MS brain lesions with CSF Chlamydia and the presence of PCR-positive patents who are clinically stable and have no enhancing MRI lesions imply the existence of a chronic infectious process.

Adult↗
PubMed2001

Phasing from an envelope.

Solution of the phase problem is central to crystallographic structure determination. Conventional molecular-replacement methods are ineffective in the absence of knowledge of the structure of a homologous protein. A recent method utilizing the low-resolution molecular shape determined from solution X-ray scattering data has been shown to be successful in locating the molecular shape within the crystallographic unit cell for the cases of the trimeric nitrite reductase (AxNiR, 105 kDa) and the dimeric superoxide dismutase (SOD, 32 kDa). This was achieved by performing a direct real-space search for orientation and translation using the orientation of the non-crystallographic axis obtained by performing a self-rotation on the crystallographic data. This effectively reduces the potential six-dimensional search to a four-dimensional one (Eulerian angle gamma and three translational parameters). The program FSEARCH incorporating this method has been generalized to handle molecules from all space groups. The program can also be used in general six-dimensional cases for a molecular-replacement solution given a predetermined envelope from any source, such as electron-microscopic images or solution scattering, provided that the envelope can be converted to the standard CCP4 map format or expressed in terms of spherical harmonics. It is hoped that this method will greatly facilitate the ab initio structure determination of proteins and provide a good foundation for further structure refinement.

Crystallography, X-Ray↗
PubMed2001

Type-1 ribosome-inactivating protein from iris (Iris hollandica var. Professor Blaauw) binds specific genomic DNA fragments.

The capacity of IRIP, a type-1 ribosome-inactivating protein (RIP) isolated from the bulbs of Iris hollandica, to bind specific DNA sequences from a mixture of approx. 200 bp (average length) fragments of total genomic DNA from Iris genome was studied. Fragments that were preferentially bound by IRIP were enriched by several cycles of affinity binding and PCR, and were cloned and sequenced. The selected DNA fragments do not share conserved sequences, indicating that IRIP does not bind DNA fragments in a strictly sequence-specific manner. According to sequence analysis, most IRIP-bound fragments contain one or more possible free energy-stable hairpin structure(s) in their secondary structure, which may be the basis for recognition between IRIP and these DNA fragments. Some, but not all, DNA fragments moderately lower the RNA N-glycosidase activity of IRIP towards rabbit reticulocyte lysate ribosomes. IRIP does not remove adenines from the binding fragments, which implies that it does not act as a polynucleotide:adenosine glycosidase towards these DNA fragments. The selective binding of IRIP to conspecific DNA fragments is also discussed in view of the novel concept that RIPs may act as DNA-binding proteins with a regulatory activity on gene expression.

Blotting, Southern↗
PubMed2001

Bis(O,O'-di-p-tolyldithiophosphato-S,S')(1,10-phenanthroline-N,N')nickel(II).

The title coordination complex, [Ni(C14H14O2PS2)2(C12H8N2)] or [Ni(pMePh-dtp)2(phen)] (phen is 1,10-phenanthroline; dtp is diaryldithiophosphate), has a non-crystallographic twofold axis of symmetry through the Ni atom and the phen moiety. Two O,O-di-p-tolyldithiophosphate (dtp) ions act as bidentate ligands. The central metal atom is coordinated by four S atoms from two dtp groups and two N atoms from the phen ligand. The title compound displays distorted octahedral geometry around the central Ni atom.

Antioxidants↗
PubMed2001

Yersinia enterocolitica O9 as a possible barrier against Y. pestis in natural plague foci in Ningxia, China.

A survey of Yersinia spp, as related to plague control, was made in Haiyuan of Ganning loess plateau plague focus, Yanchi of Inner Mongolia plateau plague focus, and Yinchuan city, as a control area, in Ningxia, China. In Haiyuan, where the main plague reservoir was Mongolian ground squirrel (Citellus alaschanicus) living in the prairie, Y. enterocolitica O9 was frequently isolated from pigs, dogs, rodents living in and around houses, but only rarely from hare and Mongolian ground squirrel. In Yanchi, where the main plague reservoir was Mongolian gerbil (Meriones unguiculatus) living in the prairie and Y. pestis, which was isolated from rodents up to 1991, Y. enterocolitica O9 was sometimes isolated from pigs and rodents. In all areas, some strains of Y. enterocolitica O3 and Y. pseudotuberculosis serotypes 3 and 4b were also isolated from pigs, dogs, and from rodents. We propose that an epidemiological link exists between the prevalence of Y. pestis and Y. enterocolitica O9 in domestic and rodents living in these areas in China. The residential area in Haiyuan may be protected against Y. pestis by the domestic animals and rodents which acquired cross-protection against Y. pestis by infection with Y. enterocolitica O9, but this is not the case in the Yanchi district.

Animals↗
PubMed2001

Ribosome-inactivating proteins from plants: more than RNA N-glycosidases?

Many plants contain proteins that are capable of inactivating ribosomes and accordingly are called ribosome-inactivating proteins or RIPs. These typical plant proteins receive a lot of attention in biological and biomedical research because of their unique biological activities toward animal and human cells. In addition, evidence is accumulating that some RIPs play a role in plant defense and hence can be exploited in plant protection. To understand the mode of action of RIPs and to optimize their medical and therapeutical applications and their use as antiviral compounds in plant protection, intensive efforts have been made to unravel the enzymatic activities of RIPs and provide a structural basis for these activities. Though marked progress has been made during the last decade, the enzymatic activity of RIPs has become a controversial issue because of the concept that RIPs possess, in addition to their classical RNA N-glycosidase and polynucleotide:adenosine glycosidase activity, other unrelated enzymatic activities. Moreover, the presumed novel enzymatic activities, especially those related to diverse nuclease activities, are believed to play an important role in various biological activities of RIPs. However, both the novel enzymatic activities and their presumed involvement in the biological activities of RIPs have been questioned because there is evidence that the activities observed are due to contaminating enzymes. We offer a critical review of the pros and cons of the putative novel enzymatic activities of RIPs. Based on the available data, it is suggested that there is little conclusive evidence in support of the presumed activities and that in the past too little attention has been given to the purity of the RIP preparation. The antiviral activity and mode of action of RIPs in plants are discussed in view of their classical and presumed novel enzymatic activities.

Antiviral Agents↗
PubMed2001

Iris bulbs express type 1 and type 2 ribosome-inactivating proteins with unusual properties.

Two closely related lectins from bulbs of the Dutch iris (Iris hollandica var. Professor Blaauw) have been isolated and cloned. Both lectins, called Iris agglutinin b and Iris agglutinin r, possess N-glycosidase activity and share a high sequence similarity with previously described type 2 ribosome-inactivating proteins (RIP). However, these lectins show only 57% to 59% sequence identity to a previously characterized type 1 RIP from iris, called IRIP. The identification of the iris lectins as type 2 RIP provides unequivocal evidence for the simultaneous occurrence of type 1 and type 2 RIP in iris bulbs and allowed a detailed comparison of type 1 and type 2 RIP from a single plant, which provides further insight into the molecular evolution of RIP. Binding studies and docking experiments revealed that the lectins exhibit binding activity not only toward Gal/N-acetylgalactosamine, but also toward mannose, demonstrating for the first time that RIP-binding sites can accommodate mannose.

Amino Acid Sequence↗
PubMed2001

Bis(O,O'-diisopropyl dithiophosphato-S,S')(1,10-phenanthroline-N,N')metal(II) complexes with cadmium(II) and iron(II).

The two title compounds, [M(C6H14O2PS2)2(C12H8N2)], where M = CdII and FeII, are isomorphous. Each compound has a crystallographic twofold axis of symmetry through the metal atom and the 1,10-phenanthroline molecule. The central metal atom is coordinated to four S atoms from the two dithiophosphate groups and two N atoms from the 1,10-phenanthroline ligand. The environment of the metal atom is a distorted octahedron.

Journal Article↗
PubMed2001

Direct-method-aided phasing of MAD data.

The direct methods of breaking the phase ambiguity intrinsic in one-wavelength anomalous scattering (OAS) data and MAD phasing are powerful methods in their own rights. In a different context, in addition to their success in phasing OAS data, direct methods can also be useful in the treatment of MAD data. The idea has been tested with the MAD data at 2.5 A resolution from the protein human adenosine kinase [Mathews et al. (1998), Biochemistry, 37, 15607--15620]. The results showed that the incorporation of direct methods in MAD phasing led to a significant improvement of phases over those obtained from the conventional MAD phasing method alone, as indicated by improved map correlation coefficients (with the existing model), reduced phase errors by 4.5 degrees and improved map connectivity.

Adenosine Kinase↗
PubMed2001

L-NAME enhances responses to atrial natriuretic peptide in the pulmonary vascular bed of the cat.

This study investigated the hypothesis that atrial natriuretic peptide (ANP) responses are mediated by particulate guanylate cyclase in the pulmonary vascular bed of the cat. When tone in the pulmonary vascular bed was raised to a high steady level with the thromboxane mimic U-46619, injections of ANP caused dose-related decreases in lobar arterial pressure. After administration of HS-142-1, an ANP-A- and ANP-B-receptor antagonist, vasodilator responses to ANP were reduced. The nitric oxide (NO) synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) enhanced ANP vasodilator responses, suggesting that inhibition of NO modulates ANP responses. L-NAME administration with constant 8-bromo-cGMP infusion attenuated the increased vasodilator response to ANP, suggesting that supersensitivity to ANP occurs upstream to activation of a cGMP-dependent protein kinase. In pulmonary arterial rings, ANP produced concentration-related vasorelaxant responses with and without endothelium. Methylene blue, L-NAME, or N(omega)-monomethyl-L-arginine did not alter ANP vasorelaxant responses. These data show that ANP supersensitivity observed in the intact pulmonary vascular bed is not seen in isolated pulmonary arterial segments, suggesting that it may only occur in resistance vessel elements. These results suggest that ANP responses occur through activation of ANP-A and/or -B receptors in an endothelium-independent manner and are modulated by NO in resistance vessel elements in the pulmonary vascular bed of the cat.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2001

[A experimental study on arthroscopic subchondral drilling for repair of osteochondral defect of temporomandibular joint (TMJ)].

OBJECTIVE: To investigate the resurfacing ability of TMJ cartilage of rhesus monkeys with osteochondral defect. METHODS: 3-millimeter-diameter, 5-millimeter-depth, cylindrical full-thickness drilled osteochondral defect of articular cartilage on the functional slope of TMJ were made on 12 rhesus monkeys(24 joints) by arthroscope. Every 3 monkeys were sacrificed at 4, 8, 12 and 24 weeks postoperatively and the repaired tissue were studied by gross observation, histology and immunohistochemical staining (IHC). RESULTS: The repaired tissues after subchondral drilling were dominated with fibrous tissues and IHC showed that Type II collagen stain was negative and Type I collagen stain was positive. CONCLUSION: The osteochondral defect in TMJ can be repaired by arthroscopic subchondral drilling. The nature of repaired tissue is fibrous connective tissue, something different from normal cartilage. Subchondral drilling can be regarded as one of the treatments for articular cartilage defect.

English Abstract↗
PubMed2000

Microenvironment of cysteine 242 in type-1 ribosome-inactivating protein from iris.

IRIP is a type-1 ribosome-inactivating protein isolated from the bulbs of Iris hollandica. It is one of the few type-1 RIPs that contain Cys residue(s) in their primary sequence. IRIP contains a single Cys residue at position 242. Although IRIP is thought to be a monomeric protein, SDS-PAGE indicates that part of the IRIP molecules can exist as disulphide bridge-linked dimers. Probing of the reactivity of the unique Cys residue by 5, 5'-dithiobis(2-nitrobenzoic acid) indicates that Cys(242) in IRIP is free but is only partially accessible to modifiers. Molecular modelling of IRIP is in agreement with this conclusion. Binding of the ligands adenine and poly(A) results in little or no effect on the conformation of Cys(242) in IRIP. Chemical modification of IRIP by a specific thiol modifier does not abolish the RNA N-glycosidase activity of IRIP, suggesting that Cys(242) is not critical for the enzymatic activity of IRIP. These results suggest that IRIP has the potential to be developed as a novel immunotoxin.

Amino Acid Sequence↗