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T Nguyen

Publications and source records attributed to T Nguyen.

At least 181 records · Page 10Linked to original sources
PubMed1998

Cloning genes encoding receptors related to chemoattractant receptors.

We report the cloning of a novel human gene (GPR32) encoding a putative G-protein-coupled receptor (GPCR) of 356 amino acids and a related pseudogene psi GPR32. The deduced amino acid sequence of GPR32 shares 35-39% identity with members of the chemoattractant receptor family. psi GPR32 shares 93% nucleotide identity with GPR32. We identified a mouse EST encoding a putative GPCR (GPR33) of 309 amino acids. The deduced amino acid sequence of GPR33 shares 30-35% identity with members of the chemoattractant receptor family and 36% identity with the receptor encoded by GPR32. The human orthologue of GPR33 contains a single basepair substitution with respect to the mouse, resulting in the presence of an in-frame stop codon within the predicted second intracellular loop, demonstrating that it is a pseudogene. Through fluorescence in situ hybridization and physical mapping of YACs, both GPR32 and psi GPR32 were mapped to chromosomal 19, region q13.3, while psi GPR33 was mapped to chromosome 14q12.

Amino Acid Sequence↗
PubMed1998

Axotomy upregulates the anterograde transport and expression of brain-derived neurotrophic factor by sensory neurons.

In addition to the known retrograde transport of neurotrophins, it is now evident that endogenous brain-derived neurotrophic factor (BDNF) is transported in the anterograde direction in peripheral and central neurons. We used a double-ligation procedure that distinguishes between anterograde and retrograde flow to quantify the anterograde transport of endogenous neurotrophins and neuropeptides in the peripheral nervous system before and after axotomy. BDNF accumulation proximal to the ligation (anterograde transport) was twice that distal to the ligation (retrograde direction). Anterograde transport of nerve growth factor and neurotrophin-3 was not evident. Furthermore, BDNF anterograde transport increased 3.5-fold within 24 hr after sciatic nerve injury or dorsal rhizotomy. Anterograde transport of substance P and calcitonin gene-related peptide decreased after peripheral nerve lesion, demonstrating that there was no generalized increase in anterograde transport. To determine the source of the anterogradely transported BDNF, we performed in situ hybridization in a variety of tissues before and after axotomy. Expression of BDNF mRNA in proximal nerve segments did not change with treatment, showing that the increased accumulation of BDNF was not a result of increased local synthesis. BDNF mRNA and protein were expressed by dorsal root ganglion sensory neurons but not by motor neurons. BDNF mRNA expression was increased 1 d after nerve injury, and BDNF protein was also increased twofold to threefold, suggesting that sensory neurons are the major contributing source of the increased BDNF traffic in the sciatic nerve. Our results suggest that increased anterogradely transported BDNF plays a role in the early neuronal response to peripheral nerve injury at sites distal to the cell body.

Animals↗
PubMed1998

[German language version and validation of the Edinburgh postnatal depression scale].

BACKGROUND AND OBJECTIVE: There is no valid method in the German literature for assessing postpartum depressive disorders. This study was undertaken to translate into German, validate and test the reliability of the Edinburgh postnatal depression scale (EPDS). PATIENTS AND METHODS: Randomly selected women after childbirth (n = 110) underwent (on the fourth postpartum day) a semistructured interview after first having answered the translated EPDS questionnaire. The diagnosis of depressive disorder was made according to the the criteria for psychological disorders in the ICD-10. For validation the results of the EPDS were compared with the clinical diagnosis of depression. The calculation of sensitivity, specificity and positive prognostic value was related to the respective EPDS results. In addition the EPDS data were analyses as to their reliability. RESULTS: The average age of the tested women was 28.6 years; 72% were married and 45% were primiparae. For an EPDS total score threshold value of 9.5 the sensitivity was 0.96, the specificity 1.0, and a positive prognostic value of 1.0. In the reliability analysis for EPDS the Guttmann split-half reliability was 0.82 and the alpha-coefficient 0.81. CONCLUSIONS: The German version of the EPDS with ten questions is an "application friendly" as well as proven to be a valid and reliable method for supporting the diagnosis of postpartum depressive disorder. It is suitable for both clinical and research use.

Adult↗
PubMed1998

Prognostic implications of p53 overexpression in cutaneous melanoma from sun-exposed and nonexposed sites.

BACKGROUND: There is increasing evidence that mutations in the p53 tumor suppressor gene are among the most common genetic alterations in human malignancies. Because ultraviolet light can induce specific p53 mutations and is linked to the development of skin cancers, this study was done to determine the significance of p53 protein (p53p) overexpression in melanomas originating at different cutaneous sites varying in frequency of sunlight exposure. METHODS: Sixty-three paraffin embedded primary and metastatic melanoma biopsy specimens from 61 patients were deparaffinized and stained with the mouse monoclonal antibody DO-1 to wild-type and mutant p53p. Twenty-eight specimens were from primary tumors and 35 specimens were from lymph node, subcutaneous, or visceral metastases. The chi-square test was used to assess the significance of p53p overexpression, and the Cox proportional hazards model was used to estimate the impact of p53p overexpression on survival. RESULTS: Of the 61 patients studied, 37 had primary cutaneous melanomas arising on chronically sun-exposed head and neck sites, 12 patients on intermittently exposed extremity sites, and 12 patients on rarely exposed trunk sites. Thirteen of the 63 primary or metastatic specimens (21%) overexpressed p53p. Overexpression of p53p was not related to patient gender or age, anatomic site of the primary tumor, Clark level, or Breslow thickness. However, those patients with p53p positive primary tumors or metastases had significantly better survival than those determined to be negative for p53p overexpression (P = 0.045). The median survival was 152.4 months for p53p positive patients versus 55.7 months for p53p negative patients. The risk ratio of dying from melanoma was 0.32 for patients with tumor specimens overexpressing p53p. CONCLUSIONS: In this study, p53p overexpression was infrequent in paraffin embedded melanoma specimens and independent of the primary melanoma's anatomic site. Although p53p overexpression was not related to other prognostic features of primary or metastatic lesions, it was associated with a significantly improved survival in this group of melanoma patients.

Adult↗
PubMed1998

Discovery of three novel G-protein-coupled receptor genes.

We report here the molecular cloning, tissue distribution, and chromosomal localization of novel genes encoding G-protein-coupled receptors (GPCRs). A search of a mouse database of expressed sequence tags revealed an EST partially encoding a GPCR, which was used to screen a mouse genomic library to obtain the translational open reading frame (ORF). The resultant clone, GPR27, contained an intronless ORF, encoding a receptor of 379 amino acids. In an alternate strategy, human genomic DNA was subjected to polymerase chain reaction (PCR) amplification, using degenerate oligonucleotides based on GPR1. Two PCR products partially encoding GPCRs were isolated and used to screen a genomic library to obtain the translational ORF. One of the resultant clones, GPR30, contained an intronless ORF encoding a receptor of 375 amino acids. The other clone, GPR35, also contained an intronless ORF encoding a receptor of 309 amino acids. Transcripts corresponding to GPR27 and GPR30 were detected in several areas of human and rat CNS, While GPR35 expression was detected only in the rat intestine. Through fluorescence in situ hybridization analysis the gene encoding GPR30 was localized to chromosome 7p22 and GPR35 to chromosome 2q37.3.

Amino Acid Sequence↗
PubMed1998

Physiological characterization of Taxol-induced large-fiber sensory neuropathy in the rat.

The cancer chemotherapeutic agent Taxol (paclitaxel) causes a dose-related peripheral neuropathy in humans. We produced a dose-dependent large-fiber sensory neuropathy, without detrimental effects on general health, in mature rats by using two intravenous injections 3 days apart. Tests of other dosing schedules demonstrated the dependence of the severity of the neuropathy and of animal health on both the dose and the frequency of dosing. Pathologically, severe axonal degeneration and hypomyelination were observed in sections of dorsal roots, whereas ventral roots remained intact. Electrophysiologically, H-wave amplitudes in the hindlimb and amplitudes of predominantly sensory compound nerve action potentials in the tail were reduced. These effects persisted for at least 4 months after treatment. Motor amplitudes were not affected, but both motor and sensory conduction velocities decreased. The ability of rats to remain balanced on a narrow beam was impaired, indicating proprioceptive deficits. Muscle strength, measured by hindlimb and forelimb grip strength, and heat nociception, measured by tail-flick and hindlimb withdrawal tests, were not affected by Taxol. This model of Taxol-induced neuropathy in mature rats, with minimal effects on general health, parallels closely the clinical syndrome observed after Taxol treatment in humans.

Animals↗
PubMed1998

Juvenile open angle glaucoma: fine mapping of the TIGR gene to 1q24.3-q25.2 and mutation analysis.

Autosomal dominant juvenile open angle glaucoma (JOAG) is an early-onset form of primary open angle glaucoma (POAG), which has been linked to chromosome 1q21-q31. Recently, mutations in the trabecular meshwork inducible glucocorticoid response gene (TIGR), one of the candidate genes mapped in this region, were identified in glaucoma patients of several families. We screened for mutations of the TIGR gene in two German families with JOAG and in 100 unselected sporadic cases of POAG. In the first family we identified a Pro370Leu mutation and in the second family a Gly367Arg mutation cosegregating with the glaucoma phenotype. No pathogenic mutation was found in 100 sporadic cases but a Tyr347Tyr polymorphism was found in two patients. Furthermore, fluorescence in situ hybridization (FISH) analysis was used to map a TIGR-specific yeast artificial chromosome to 1q24.3-q25.2.

Adolescent↗
PubMed1998

Correlates of in-hospital cost among patients undergoing abdominal aortic aneurysm repair.

BACKGROUND: Surgical repair of abdominal aortic aneurysms (AAA) is increasingly being performed, but little is known about the correlates of in-hospital cost associated with this procedure. METHODS AND RESULTS: Baseline clinical characteristics, in-hospital outcomes, and total in-hospital costs were examined among a retrospective cohort of 71 patients who underwent AAA repair. Median age was 68 years, and 75% of the patients were men. High-risk characteristics for perioperative complications were common and included hypertension (73%), documented coronary artery disease (66%), smoking (60%), previous myocardial infarction (47%), history of congestive heart failure (12%), urgent or emergent AAA repair (16%), and diabetes mellitus (11%). Perioperative complications included congestive heart failure (13%), myocardial infarction (11 %), and death (1 %). Median length of stay in the surgical intensive care unit (SICU) was 2 days (range 0 to 28), and median in-hospital stay was 9 days (range 5 to 39). In-hospital cost for the 71 patients ranged from $13,766 to $82,435 (mean $25,931, median $21,633). Univariate and multiple linear regression analyses demonstrated that among the potential correlates investigated, number of SICU days (P= .007) and total length of stay (P< .0001) were the most closely associated with in-hospital cost. CONCLUSIONS: Among patients undergoing AAA repair, the major correlates of in-hospital cost are the number of days spent in the SICU and the total number of days spent in the hospital. These results suggest that any intervention that reduces length of stay may significantly reduce the total in-hospital cost associated with AAA repair.

Aged↗
PubMed1998

Tensile bond strengths of dual-cured cements between a glass-ceramic and enamel.

STATEMENT OF THE PROBLEM: Dual-cured cements have been used with castable ceramic restorations, but the tensile bond strengths of these materials have not been thoroughly researched. PURPOSE OF THE STUDY: This study compared the tensile bond strengths between Dicor castable ceramics and enamel of four dual-cure cements: Twinlook, Optec Dual-Cure Luting Cement, Clearfil CR Inlay, and Dual Cement. MATERIAL AND METHODS: Truncated cones made of Dicor castable ceramics were cemented to enamel of freshly extracted anterior teeth with these four cements. Before testing, all specimens were immersed in water at 37 degrees C for 24 hours, and thermocycled 1000 times in 5 degrees C and 55 degrees C water, with a dwell time of 30 seconds each. Tensile force was used to separate each specimen with the Instron universal testing machine. RESULTS: Clearfil CR Inlay cement exhibited the highest mean tensile bond strength (18.4 MPa), followed by Dual (18.3 MPa), Twinlook (15.2 MPa), and Optec Dual-Cure luting (14.9 MPa) cements. One-way analysis of variance did not reveal any significant differences (p = 0.05) among groups. A majority of the fracture was adhesive at the ceramic and cement interface. CONCLUSION: All four dual-cured cements formed strong bonds between enamel and Dicor cement, ranging from 14.90 MPa to 18.35 MPa, and there was no statistically significant difference.

Analysis of Variance↗
PubMed1998

The Jarisch-Herxheimer reaction and fetal monitoring changes in pregnant women treated for syphilis.

OBJECTIVE: To estimate the incidence of the Jarisch-Herxheimer reaction in pregnant women undergoing treatment of syphilis and the incidence of changes in uterine activity or fetal heart rate (FHR). METHODS: Pregnant women of at least 24 weeks' gestation diagnosed as needing treatment of syphilis were reviewed retrospectively. Patients were admitted for their first dose of benzathine penicillin, and the FHR was recorded continuously before and for 24 hours after injection. The occurrence of the Jarisch-Herxheimer reaction was noted, and all available FHR records for this admission were reviewed. Evaluations for changes in the FHR pattern and uterine activity were made. Statistical comparisons used Student t, Fischer exact, and chi2 tests, when applicable (significance P < .05). RESULTS: We reviewed 50 charts and 31 available FHR records. The average gestational age was 30.8 weeks. We found 20 cases of probable Jarisch-Herxheimer reaction (40%). Thirteen of 31 patients (41.9%) developed regular uterine contractions, median onset, 10 hours. All resolved within 24 hours of treatment. Patients with uterine contractions had a greater mean increase in temperature (1.15F versus 0.68F, P < .008). Twelve of 31 women (38.7%) developed recurrent variable decelerations, median onset, 8 hours. All patients but one had their contractions resolve within 24 hours of treatment. Lower gestational age was associated with the occurrence of recurrent variable decelerations (29.6 weeks versus 32.3 weeks, P < .05). No patients required delivery at the time of treatment. CONCLUSION: The incidence of Jarisch-Herxheimer reaction in treated syphilitic pregnancies is about 40%; similar proportions of patients develop regular uterine contractions and recurrent variable decelerations.

Adult↗
PubMed1998

Aortoiliac reconstructive surgery based upon the results of duplex scanning.

OBJECTIVE: To evaluate whether duplex scanning can replace angiography in patients operated for aortoiliac obstructive disease. DESIGN: Retrospective. MATERIALS AND METHODS: Between January 1995 and October 1996, 44 patients underwent vascular surgery of the aortoiliac tract. The study population was divided into two groups; patients operated upon the results of duplex scanning only and patients who also underwent angiography prior to surgery. The additional value of angiography and the differences between both groups concerning unexpected peroperative findings, early postoperative failures and the need for additional radiological or surgical interventions in the first three postoperative months were studied. RESULTS: Duplex scan group: 22 patients were operated upon the results of duplex scanning only. In two patients surgical strategy had to be changed. Early postoperative graft occlusion occurred in one case. A haemodynamically significant graft stenosis within 3 months of surgery occurred in one patient. Duplex/angiography group: 22 patients underwent both duplex scanning and angiography. Six patients underwent diagnostic angiography after failed duplex scanning. In 10 patients angiography was part of percutaneous transluminal angioplasty prior to surgery. In six patients angiograms were performed after successful duplex scanning. Angiography failed in two patients and added information in four of 16 patients. Unexpected findings at operation occurred in four patients. Graft stenosis within 3 months was detected in three patients. CONCLUSION: After successful duplex scanning information obtained by angiography has only a limited impact on therapeutic decision-making. In the majority of patients vascular reconstructive surgery of aortoiliac arteries can be planned based on duplex scanning only.

Adult↗
PubMed1998

Aggregation of recombinant human interferon gamma: kinetics and structural transitions.

Protein aggregation is a complex phenomenon that can occur in vitro and in vivo, usually resulting in the loss of the protein's biological activity. While many aggregation studies focus on a mechanism due to a specific stress, this study focuses on the general nature of aggregation. Recombinant human interferon-gamma (rhIFN-gamma) provides an ideal model for studying protein aggregation, as it has a tendency to aggregate under mild denaturing stresses (low denaturant concentration, temperature below the Tm, and below pH 5). All of the aggregates induced by these stresses have a similar structure (high in intermolecular beta-sheet content and a large loss of alpha-helix) as determined by infrared and circular dichroism spectroscopy. Thermally induced and denaturant-induced aggregation processes follow first-order kinetics under the conditions of this study. Spectroscopic and kinetic data suggest that rhIFN-gamma aggregates through an intermediate form possessing a large amount of residual secondary structure. In contrast to the aggregates formed under denaturing stresses, the salted-out protein has a remarkably nativelike secondary structure.

Humans↗
PubMed1998

Increased spontaneous apoptosis in T lymphocytes in DiGeorge anomaly.

The aim of this study was to determine whether increased apoptosis in peripheral blood lymphocytes plays a role in T cell deficiency associated with DiGeorge anomaly. T cell subsets from a patient with DiGeorge anomaly were examined for the expression of Fas, FasL, Bcl-2 and Bcl-XL at the protein level with monoclonal antibodies, using dual-colour flow cytometry, and at the mRNA level in mononuclear cells by quantitative reverse transcriptase-polymerase chain reaction. In vitro spontaneous apoptosis was examined by propidium iodide staining and DNA fragmentation, using flow cytometry and gel electrophoresis, respectively. Fas and FasL expression, both at the level of protein and of mRNA, was increased, whereas Bcl-2 expression was decreased both at the level of protein and of mRNA. However, no difference in Bcl-XL expression was observed between the patient and an age-matched control. A significant proportion of both CD4+ and CD8+ T cells from the patients underwent spontaneous apoptosis, whereas almost no spontaneous apoptosis was observed in the age-matched control. These data suggest that spontaneous apoptosis in T lymphocytes, at least in part, may be responsible for T cell deficiency in DiGeorge anomaly.

Adolescent↗
PubMed1998

Molecular characterization and expression of cloned human galanin receptors GALR2 and GALR3.

Galanin is a 29- or 30-amino acid peptide with wide-ranging effects on hormone release, feeding behavior, smooth muscle contractility, and somatosensory neuronal function. Three distinct galanin receptor (GALR) subtypes, designated GALR1, 2, and 3, have been cloned from the rat. We report here the cloning of the human GALR2 and GALR3 genes, an initial characterization of their pharmacology with respect to radioligand binding and signal transduction pathways, and a profile of their expression in brain and peripheral tissues. Human GALR2 and GALR3 show, respectively, 92 and 89% amino acid sequence identity with their rat homologues. Radioligand binding studies with 125I-galanin show that recombinant human GALR2 binds with high affinity to human galanin (K(D) = 0.3 nM). Human GALR3 binds galanin with less affinity (IC50 of 12 nM for porcine galanin and 75 nM for human galanin). Human GALR2 was shown to couple to phospholipase C and elevation of intracellular calcium levels as assessed by aequorin luminescence in HEK-293 cells and by Xenopus melanophore pigment aggregation and dispersion assays, in contrast to human GALR1 and human GALR3, which signal predominantly through inhibition of adenylate cyclase. GALR2 mRNA shows a wide distribution in the brain (mammillary nuclei, dentate gyrus, cingulate gyrus, and posterior hypothalamic, supraoptic, and arcuate nuclei), and restricted peripheral tissue distribution with highest mRNA levels detected in human small intestine. In comparison, whereas GALR3 mRNA was expressed in many areas of the rat brain, there was abundant expression in the primary olfactory cortex, olfactory tubercle, the islands of Calleja, the hippocampal CA regions of Ammon's horn, and the dentate gyrus. GALR3 mRNA was highly expressed in human testis and was detectable in adrenal gland and pancreas. The genes for human GALR2 and 3 were localized to chromosomes 17q25 and 22q12.2-13.1, respectively.

Amino Acid Sequence↗
PubMed1998

SPECT electronic collimation resolution enhancement using chi-square minimization.

An electronic collimation technique is developed which utilizes the chi-square goodness-of-fit measure to filter scattered gammas incident upon a medical imaging detector. In this data mining technique, Compton kinematic expressions are used as the chi-square fitting templates for measured energy-deposition data involving multiple-interaction scatter sequences. Fit optimization is conducted using the Davidon variable metric minimization algorithm to simultaneously determine the best-fit gamma scatter angles and their associated uncertainties, with the uncertainty associated with the first scatter angle corresponding to the angular resolution precision for the source. The methodology requires no knowledge of materials and geometry. This pattern recognition application enhances the ability to select those gammas that will provide the best resolution for input to reconstruction software. Illustrative computational results are presented for a conceptual truncated-ellipsoid polystyrene position-sensitive fibre head-detector Monte Carlo model using a triple Compton scatter gamma sequence assessment for a 99mTc point source. A filtration rate of 94.3% is obtained, resulting in an estimated sensitivity approximately three orders of magnitude greater than a high-resolution mechanically collimated device. The technique improves the nominal single-scatter angular resolution by up to approximately 24 per cent as compared with the conventional analytic electronic collimation measure.

Algorithms↗