Biomedical subjects

T Q Pham

Publications and source records attributed to T Q Pham.

8 recordsLinked to original sources

PubMed2001

Detection of novel gene expression in paraffin-embedded tissues by isotopic in situ hybridization in tissue microarrays.

Correlating altered gene expression patterns with particular disease states is a critical step in understanding disease processes and developing treatment strategies. Many thousands of novel gene sequences have recently been annotated in public and private databases and are now available for analysis. Tissue-specific expression patterns of these sequences can be evaluated physically on DNA arrays and other high throughput assays, or virtually by bioinformatics mining of expressed sequence tag (EST) databases. As a secondary screening tool, in situ hybridisation (ISH) not only confirms tissue specificity, but also reveals what is often valuable information about cell-type expression patterns of nov16l sequences. Due to their availability and long-term stability at room temperature, formalin-fixed paraffin-embedded clinical specimens provide an invaluable resource for evaluating expression patterns of novel human genes. We describe a high-throughput approach for identifying and quantifying the expression of novel genes in paraffin-embedded human tissues using isotopic in situ hybridisation and tissue microarrays (TMA).

Blotting, Northern↗

PubMed2000

Antioxidant properties of crocin from Gardenia jasminoides Ellis and study of the reactions of crocin with linoleic acid and crocin with oxygen.

Crocin-a water soluble carotenoid-is found in the fruits of gardenia (Gardenia jasminoides Ellis) and in the stigmas of saffron (Crocus sativus Linne). For crocin purification, gardenia fruits are extracted with 50% acetone, followed by ether washing, ion exchange, and separation by preparative HPLC. Purified crocin with purity of >99.6% has an antioxidative activity at concentrations up to 40 ppm. At 20 ppm the antioxidative activity of crocin is comparable to that of BHA. The antioxidant property of crocin as evaluated by the thiocyanate method was better than with the thiobarbituric acid method. The adduct between the linoleic acid radical and crocin was detected by LC-MS. When crocin reacted with oxygen in the presence of FeSO(4), intermediates such as monohydroperoxides and dihydroperoxides of crocin were formed and detected by LC-MS.

Antioxidants↗

PubMed1997

Molecular cloning and characterization of Dr-II, a nonfimbrial adhesin-I-like adhesin isolated from gestational pyelonephritis-associated Escherichia coli that binds to decay-accelerating factor.

Bacterial adhesins play an important role in the colonization of the human urogenital tract. Escherichia coli Dr family adhesins have been found to be frequently expressed in strains associated with pyelonephritis in pregnant females. The tissue receptor for known Dr adhesins has been localized to the short consensus repeat-3 (SCR-3) domain of decay accelerating factor (DAF), a complement regulatory protein. In this report, we identified and cloned draE2, a gene encoding a novel 17-kDa DAF-binding adhesin, Dr-II, from a strain of E. coli associated with acute gestational pyelonephritis. Despite the significant sequence diversity between Dr-II and Dr family adhesins, the receptor of Dr-II was found to be the SCR-3 domain of DAF. Sequence analysis of the 186-amino-acid Dr-II open reading frame revealed significant diversity from other members of the Dr adhesin family, including Dr, AFA-I, AFA-III, and F1845, but only an 8-amino-acid difference in sequence from that of the 17-kDa nonfimbrial adhesin NFA-I of unknown receptor specificity. N-terminal peptide sequencing of the purified adhesin confirmed the identity of the open reading frame and indicated cleavage of a 28-amino-acid signal peptide. Antibodies raised against purified Dr-II adhesin exhibited little or no cross-reactivity to Dr adhesin. Characterization of the biological properties demonstrated that like the Dr adhesins, Dr-II was associated with the ability of E. coli to bind to tubular basement membranes and Bowman's capsule and to be internalized into HeLa cells.

Adhesins, Escherichia coli↗

PubMed1997

Routine transition zone and seminal vesicle biopsies in all patients undergoing transrectal ultrasound guided prostate biopsies are not indicated.

PURPOSE: Transrectal ultrasound guided biopsies of the transition zone and seminal vesicles have been useful in select patients. More widespread use of these additional biopsies has been proposed. The efficacy of routine transition zone and seminal vesicle biopsies was examined. MATERIALS AND METHODS: From January 1988 to October 1994, 736 transrectal ultrasound guided systematic sextant biopsies were performed. From October 1994 to July 1995, 161 consecutive patients underwent transrectal ultrasound with systematic sextant, transition zone and seminal vesicle biopsies. RESULTS: Of the 736 patients undergoing only sextant biopsies 309 (42.0%) had cancer and 24 (3.3%) required repeat biopsy, compared to 55 (34.2%) and 4 (2.5%) of 161 undergoing combined sextant, transition zone and seminal vesicle biopsies. Prostate cancer was found only in the systematic sextant biopsies in 43 of the former 55 patients (78.2%), and in the transition zone and systematic sextant biopsies in 11 (20.0%). One patient (1.8% of patients with cancer or 0.6% of all 161 patients) had cancer in only the anterior biopsies and 6 (10.9 and 3.7%, respectively) had cancer involving the seminal vesicles. CONCLUSIONS: Routine transition zone and seminal vesicle biopsies in all patients undergoing transrectal ultrasound guided systematic sextant biopsies are not warranted.

Aged↗

PubMed1996

Determination of the number and location of the manganese binding sites of DNA quadruplexes in solution by EPR and NMR in the presence and absence of thrombin.

The interaction of a DNA quadruplex with thrombin has been studied by first determining the sites of manganese binding to the quadruplex in the absence of thrombin. This has been followed by determining if the interactions with thrombin displace the bound manganese. A different DNA quadruplex has also been studied as a control. The refined solution structures of two DNA quadruplexes have been used to predict the electrostatic potentials of these DNAs. The calculated electrostatic potentials have been used to predict the locations of the binding sites of the paramagnetic ion manganese to these DNAs. The enhanced relaxation of DNA protons due to the binding of the paramagnetic metal ion Mn2+ has been used to experimentally determine the locations of the binding sites. The NMR results and the predictions based on the electrostatic potentials both place the binding sites of the manganese in the narrow grooves of these quadruplex DNAs. The predicted locations are spatially close to those experimentally observed, and the predicted and experimental locations also have similar electrostatic potential energy. These results have allowed a validation of the predictions of electrostatic potentials from structure. The 15mer quadruplex has two strong Mn2+ binding sites with one in each narrow groove. Both Mn2+ are released when the 15mer is complexed with thrombin, indicating that both narrow grooves are involved in the 15mer-thrombin interactions. The dimer quadruplex has a different structural motif than the 15mer and the presence of thrombin does not appreciably affect its interactions with Mn2+.

Base Sequence↗

PubMed1994

Decay-accelerating factor is expressed in the human endometrium and may serve as the attachment ligand for Dr pili of Escherichia coli.

PROBLEM: We evaluated the hypothesis that different tissue substructures in uteri may express decay accelerating factor (DAF), a complement regulatory protein that also may serve as ligand for bacterial attachment. METHOD: Purified Dr pili, anti-Dr pili IgG, anti-DAF (SCR-3) IgG, and fluorescein-isothiocyanate-conjugated secondary IgG were used for binding and inhibition experiments. RESULT: We observed staining of endometrial glands, spiral arterioles, and myometrial arteries with Dr adhesin (pili) and anti-DAF (SCR-3) IgG, and found variation in distribution and amount of Dr ligands in different individuals. Anti-DAF (SCR-3) IgG blocked the binding of Dr pili to the endometrium. CONCLUSION: Presence of DAF in endometrium may protect tissues from complement-induced damage. Differences between individuals in DAF density in the endometrium may affect sensitivity to attachment of Dr-bearing E. coli and/or complement activation.

Adhesins, Bacterial↗

PubMed1994

Implementing a Physician's Workstation using client/server technology and the distributed computing environment.

PWS is a physician's workstation research prototype developed to explore the use of information management tools by physicians in the context of patient care. The original prototype was implemented in a client/server architecture using a broadcast message server. As we expanded the scope of the prototyping activities, we identified the limitations of the broadcast message server in the areas of scalability, security, and interoperability. To address these issues, we reimplemented PWS using the Open Software Foundation's Distributed Computing Environment (DCE). We describe the rationale for using DCE, the migration process, and the benefits achieved. Future work and recommendations are discussed.

Ambulatory Care Information Systems↗

PubMed1990

Identification of a cell-surface DNA receptor and its association with systemic lupus erythematosus.

We have previously reported the existence of a cell-membrane-associated molecule on human PBMC, which binds DNA and has the characteristics of a receptor. Monoclonal antibodies have been made to this receptor and have been used successfully for the purification of this cell-surface molecule. Preliminary studies have indicated a receptor for DNA on murine kidney and spleen cells which is similar in molecular weight to the human DNA receptor (30 kD). The occurrence of autoantibodies to cell-surface receptors has been described in several autoimmune diseases and we have noted that the serum of patients with lupus and similar disorders inhibit the binding of labeled DNA to human leukocytes. Using a "dot-blot" assay with affinity-purified human DNA receptor, sera from patients with various CTD and from healthy volunteers were screened for anti-receptor antibodies; anti-receptor antibodies were found in many patients with CTD and some of their first-degree relatives. The prevalence of anti-receptor antibodies in normal blood donors was less than 2%. It is hypothesized that anti-receptor antibodies represent an early immune response in lupus and kindred disorders and that anti-DNA antibodies may arise from the corresponding anti-idiotypic response.

Antibodies↗