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Biomedical subjects

T Truong

Publications and source records attributed to T Truong.

33 records · Page 2Linked to original sources
PubMed1996

Immunogenic and protective response in mice immunized with a purified, inactivated, Dengue-2 virus vaccine prototype made in fetal rhesus lung cells.

The feasibility of a purified, inactivated vaccine (PIV) against dengue type 2 (DEN-2) virus was explored. Dengue-2 virus strain 16681 was used for producing a monotypic PIV. Virus adapted to fetal rhesus lung (FRhL-2) cells was harvested from roller bottle culture supernatant fluids, concentrated, and purified on sucrose gradients. Analysis of purified virus preparations by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting showed primarily envelope (E) and premembrane (prM) antigens. These preparations had a purity, estimated from silver-stained gels, of approximately 70%, and a yield, based on recovery of virus and viral antigen, of 10-20%. The purified virus was inactivated with 0.05% formalin at 22 degrees C, or alternatively, with 7 mRads from a 60Co source. Vaccinated mice developed high titers of anti-DEN-2 virus neutralizing antibody and were partially protected from virus challenge. These results warrant further testing and development of PIVs for the other DEN virus serotypes.

Animals↗
PubMed1995

Expression of thrombospondins by endothelial cells. Injury is correlated with TSP-1.

The thrombospondins (TSP-1, -2, and -3) comprise a family of proteins that are homologous at the carboxy terminus but have unique sequences at the amino terminus that might be correlated with the regulation of cell behavior. To investigate the expression of TSP-1, -2, and -3 in endothelial cells, we examined developing murine blood vessels and human atherosclerotic plaques by in situ hybridization. The expression of TSP-1 was also characterized in cultured bovine aortic endothelial cells. Expression of TSP-2 was seen in the dorsal aorta as early as embryonic day 10; TSP-1 was not detected in endothelial cells until later stages, and TSP-3 was not apparent in the vasculature. In atherosclerotic specimens, TSP-1 mRNA was detected in many intraplaque microvessels and in the endothelium lining the atheromatous plaque; TSP-2 was absent from these regions. Cultured bovine aortic endothelial cells did not transcribe TSP-2 mRNA at detectable levels. There were high steady-state levels of TSP-1 mRNA in subconfluent bovine aortic endothelial cells before confluence and at the wound edge after injury of the cell monolayer, with maximal expression of TSP-1 in cultures at a time during which approximately 35% of the cells were in S phase. As the majority of these cells subsequently undergo mitosis, these data are consistent with TSP-1 as an inhibitor of endothelial cell proliferation that functions in G1. These results support the conclusion that, despite sequence homology, the TSPs have distinct functions in vascular biology.

Animals↗
PubMed1994

Photodynamic biologic tissue glue.

We studied both heat- and light-activated tissue glues, and while a heat-activated mixture such as albumin and fluorescein isothiocyanate was effective, we believed that a light-activated substance would have less of an effect on adjacent tissue. Our glue uses a photosensitive singlet oxygen generator to cross-link a protein solder with corneal stromal collagen. The mixture consists of 18% fibrinogen and 2.6 mg/ml of riboflavin-5-phosphate activated with a blue-green (488-514 nm) Argon laser. We tested our glue by soldering 5-mm penetrating central corneal incisions made in human cadaver eyes. The strength of the closure was measured by cannulating the vitreous cavity with an 18-gauge needle connected to a saline reservoir. The pressure in the reservoir was elevated by connecting it to a sphygmomanometer. Immediately following tissue closure, the intraocular pressure was increased until the wound burst. We soldered and measured 10 eyes and found a mean bursting pressure of 154 mm Hg, with a range of 80-260 mm Hg. Our laser-activated tissue glue is an effective adhesive for corneal tissue, and we now plan to carry out toxicity studies in living animals.

Cornea↗
PubMed1994

Recent advances in stannous fluoride technology: antibacterial efficacy and mechanism of action towards hypersensitivity.

Stannous fluoride (SnF2) is highly susceptible to oxidation and hydrolysis but both anhydrous and aqueous preparations can be well established by proper formulation. When stability in aqueous preparations is achieved by the use of certain strong complexing agents, reduced antibacterial activity is observed which may be attributed to reduced bioavailability of the stannous ion. In contrast, an anhydrous SnF2 preparation maintains stannous ion in a stable but, uncomplexed form. This preparation displays antibacterial activity in saliva and delivers stannous ion which is absorbed onto surfaces making them less susceptible to plaque formation for an extended period of time (hours). When this anhydrous preparation is brushed onto dentine in vitro or in situ, one observes a nearly complete coverage of the dentine surface and occlusion of tubules by a tin-rich surface deposit. This finding indicates that the observed clinical efficacy of this preparation at relieving hypersensitivity is due to occlusion of tubules by a mixture of low solubility complexes of tin. A water-based SnF2 preparation containing strongly complexed stannous ions does not form a surface coating on dentine in vitro suggesting that this preparation may not be optimal for treating hypersensitivity. Overall, the findings indicate that the stannous ions in a SnF2 preparation must be maintained in a stable, bioavailable form for optimal efficacy against plaque and hypersensitivity to be obtained. The results suggest that these properties are provided by stable anhydrous preparations but are difficult to achieve simultaneously in aqueous preparations. When properly formulated, stannous fluoride preparations can provide multiple oral therapeutic benefits.

Bacteria↗
PubMed1994

Evaluation of a new dentifrice for the treatment of sensitive teeth.

A dentifrice containing 5% potassium nitrate, 1.3% soluble pyrophosphate, 1.5% polyvinylmethyl ether and maleic acid (PVM/MA) copolymer and 0.243% sodium fluoride in a silica base (Sensitive/Tartar Control) has been developed to concomitantly control tartar, caries and dentinal hypersensitivity. In vitro and animal studies show that the fluoride in this product effectively inhibits formation of enamel and dentine caries. In vitro studies also demonstrate that this dentifrice effectively reduces hydraulic conductance by occluding dentine tubules with a mixed surface deposit of copolymer and silica. Using an in vitro model that simulates in vivo conditions, this dentifrice also allows a rapid penetration of potassium nitrate through the dentine matrix. These findings demonstrate a correlation under in vivo conditions between the occlusion of dentine and the ability to deliver topically applied agents to target sites within or below dentine. The results indicate that this new dentifrice should provide multiple clinical therapeutic benefits including controlling tooth decay and tartar formation, and reducing and preventing dentinal hypersensitivity.

Animals↗
PubMed1994

Thermodontic stimulator--a new technology for assessment of thermal dentinal hypersensitivity.

A clinical investigation of the reproducibility of threshold and pain temperature scores obtained from use of the Thermodontic Stimulator (TDS) is reported. The TDS is designed for accurate clinical testing of thermal dentinal hypersensitivity. This instrument employs a variable stimulus/fixed response approach to clinical testing of thermal dentinal hypersensitivity. The TDS consists of a probe in a handpiece, a patient signaling device (joystick), a computer, and interface electronics. The TDS provides a precise means of assessing and recording the temperature which elicits a response to thermal stimulation from the subject being evaluated. Two temperatures are recorded. The threshold temperature is recorded when the patient is first able to sense that a cold stimulus has been applied to the tooth. The second score, pain temperature, is recorded when the subject first notices discomfort. Twenty-two subjects participated in this study. Results obtained from the 21 subjects who completed this study (one subject dropped out for non-compliance) demonstrated a reproducibility standard deviation of 1.1 degrees C for the threshold temperature, and 2.8 degrees C for the pain temperature for the duration of the study. There was a good degree of correlation between the measurements of any two test days (Pearson's correlation coefficient). There was no significant difference between the mean pain temperature scores of any two testing days.

Cold Temperature↗
PubMed1993

Reading ability in patients in substance misuse treatment centers.

Adult inpatients in state-supported (public) and private substance misuse treatment settings were tested for reading ability. Patient education materials and consent forms were assessed for readability levels. Public patients' mean reading levels were significantly lower than those of private patients, and were 4 to 5 years below the level needed to read and understand standard treatment materials. More than half of the public and almost one-third of the private patients tested were reading below a 9th grade level. Standard treatment materials were written on 11th to 12th grade reading levels; admission and consent forms were written on 12th to 18th grade levels. Patients in substance misuse settings should be tested for literacy levels upon admission and provided with materials commensurate with their reading ability.

Adolescent↗
PubMed1992

Dictyostelium myosin II heavy-chain kinase A is activated by heparin, DNA and acidic phospholipids and inhibited by polylysine, polyarginine and histones.

Dictyostelium myosin II heavy-chain kinase A (MHCK A) is activated by autophosphorylation. Heparin and DNA, as well as vesicles composed of phosphatidylserine or phosphatidylinositol, were found to increase the initial rate of MHCK A autophosphorylation 5-10-fold in a Ca(2+)-independent manner. The negatively charged molecules also increased the activity of the autophosphorylated MHCK A by about 2-fold. In contrast, positively charged polypeptides such as poly(D-lysine), poly(L-lysine), poly(L-arginine) and histones strongly inhibited (IC50 of 0.5 micrograms/ml) the activity of the active, autophosphorylated MHCK A. Similar levels of inhibition, on a weight basis, were observed for poly(L-lysine) fractions with molecular weights from 3800 to 150,000-300,000. The inhibition was competitive with respect to peptide substrate and mixed with respect to ATP. At much higher concentrations poly(L-lysine) also inhibited the ability of MHCK A to autophosphorylate. It is proposed that negatively charged compounds and autophosphorylation increase the activity of MHCK A by weakening the interaction between the catalytic domain and a positively charged autoinhibitory domain.

Animals↗
PubMed1992

Actin-activated Mg-ATPase activity of Dictyostelium myosin II. Effects of filament formation and heavy chain phosphorylation.

The actin-activated Mg-ATPase activities of unphosphorylated and heavy chain phosphorylated Dictyostelium myosin II and of a Dictyostelium myosin II heavy meromyosin (HMM) fragment were examined at different Mg2+ and KCl concentrations. The Mg-ATPase activity of HMM displayed a maximum rate, Vmax, of about 4.0/s and a Kapp (actin concentration required to achieve 1/2 Vmax) that increased from 8 to 300 microM as the KCl concentration increased from 0 to 120 mM. When assayed with greater than 5 mM Mg2+ and 0 mM KCl the unphosphorylated Dictyostelium myosin II yielded a Kapp of 0.25 microM and a Vmax of 2.8/s. At lower Mg2+ concentrations or with 50 mM KCl the data were not fit well by a single hyperbolic curve and Kapp increased to 25-100 microM. The increase in Kapp did not correlate with the loss of sedimentable filaments. At KCl concentrations above 100 mM Vmax increased to greater than 4/s. Heavy chain phosphorylated myosin (3.5 mol of phosphate/mol myosin) displayed a Vmax of about 5/s and a Kapp of 50 microM under all conditions tested. Thus, heavy chain phosphorylation inhibited the actin-activated Mg-ATPase activity of Dictyostelium myosin II in 5-10 mM Mg2+ and low ionic strength through an increase in Kapp.

Actins↗
PubMed1992

Detection and partial characterization of proopiomelanocortin-related end-products from the pars intermedia of the toad, Bombina orientalis.

Steady-state analyses were performed on the proopiomelanocortin (POMC)-related end-products present in acid extracts of the pars intermedia of the anuran amphibian, Bombina orientalis. Sephadex G-75 gel filtration chromatography indicated that immunoreactive alpha-MSH-sized material and N-acetylated beta-endorphin-related material are the major POMC-related products present in this tissue. The alpha-MSH-sized immunoreactivity was further fractionated by reversed phase HPLC. The major peak of immunoreactivity isolated by this procedure eluted with the same retention time as synthetic ACTH(1-13)amide. Cation exchange chromatography supported the conclusion that the major storage form of alpha-MSH in the pars intermedia of Bombina is ACTH(1-13)amide. Analysis of Bombina pars intermedia in culture indicated that mono-acetylated and di-acetylated alpha-MSH were the major forms of alpha-MSH secreted into the medium. The major peak of N-acetylated beta-endorphin-related material was further analyzed by cation exchange chromatography and Sephadex G-25 gel filtration column chromatography. The major storage form of beta-endorphin in this tissue is N-acetylated, has a net positive charge at pH 2.75 of +1, and has an apparent molecular weight of 1.2K. The beta-endorphin present in the pars intermedia of this tissue does not undergo further N-acetylation at the time of secretion. These results indicate that in the pars intermedia of the archaeobatrachian, Bombina orientalis, the N-acetylation of alpha-MSH is a cosecretory processing event, whereas N-acetylation of beta-endorphin is a post-translational processing event. These results are compared to other archaeobatrachian and neobatrachian pituitary POMC systems that have been analyzed.

Animals↗
PubMed1992

The Harvard Trauma Questionnaire. Validating a cross-cultural instrument for measuring torture, trauma, and posttraumatic stress disorder in Indochinese refugees.

There are no valid and reliable cross-cultural instruments capable of measuring torture, trauma, and trauma-related symptoms associated with the DSM-III-R diagnosis of posttraumatic stress disorder (PTSD). Generating such standardized instruments for patients from non-Western cultures involves particular methodological challenges. This study describes the development and validation of three Indochinese versions of the Harvard Trauma Questionnaire (HTQ), a simple and reliable screening instrument that is well received by refugee patients and bicultural staff. It identifies for the first time trauma symptoms related to the Indochinese refugee experience that are associated with PTSD criteria. The HTQ's cultural sensitivity may make it useful for assessing other highly traumatized non-Western populations.

China↗
PubMed1990

Assessing symptom change in Southeast Asian refugee survivors of mass violence and torture.

The authors evaluated changes in symptoms and levels of perceived distress of 21 Cambodian, 13 Hmong/Laotian, and 18 Vietnamese patients before and after a 6-month treatment period. Most of the patients improved significantly. Cambodians had the greatest and Hmong/Laotians had the least reductions in depressive symptoms. Although psychological symptoms improved, many somatic symptoms worsened. The authors conclude that refugee survivors of multiple traumata and torture can be aided by psychiatric care. They recommend investigations with larger samples and suitable control groups to further clarify the relative contributions of trauma, diagnosis, and acculturation stress to treatment outcome.

Acculturation↗
PubMed1987

Cysteamine induces cataracts in newborn rats.

Daily subcutaneous injections of cysteamine (CSH) administered to neonatal rats for 6 to 11 days cause dense bilateral cataracts that are evident at eye opening and that are permanent. CSH has been previously shown to induce protein cross-linking by the formation of abnormal disulfide bonds. It is hypothesized that the same mechanism underlies its cataractogenic effect; as such, CSH may be a useful agent in the study of models of senile cataract formation in humans.

Animals↗
PubMed1985

Creatine phosphokinase isoenzymes in human prostatic tissues: a comparison between benign hyperplasia and adenocarcinoma.

The objective of this study was to determine the distribution of creatine phosphokinase (CPK) into its three isoenzymes, MM, MB, and BB, in human prostatic tissue, in patients with benign hyperplasia (BPH) and adenocarcinoma. Specimens were obtained from 23 patients with adenocarcinoma of the prostate and 25 patients with benign hyperplasia. We also had the opportunity to analyze the CPK content in two normal prostates, the first from a 16 1/2-year-old boy and the second from a 9 1/2-year-old child. Our results showed prostate tissue to contain almost exclusively the BB isoenzyme with traces of the MB and MM dimers in both cancer and BPH as well as the specimen of normal prostate from the 16 1/2-year-old boy. As for the 9 1/2-year-old child, we found the following distribution: 39% MM, 21% MB, and 40% BB dimer. A comparison of the CPK-BB content in benign hyperplasia and adenocarcinoma revealed no significant difference between the two groups. Furthermore, we tried to correlate prostatic tissue CPK-BB levels with another possible tumor marker of the prostate, prostatic acid phosphatase (PAP) measured in the cytosol. No correlation was found between these two markers. We also studied the relationship of CPK-BB and PAP content in prostatic tissue to nuclear and cytosolic androgen receptor content in human prostatic tissue. We found some correlation between CPK-BB and androgen cytosolic receptors as well as between PAP content and androgen cytosolic receptors in patients with benign hyperplasia. No such correlation was found in the group with adenocarcinoma. In conclusion, this study does not show that the measurement of CPK-BB in the prostatic tissue could be used as an index of tissue malignancy.

Acid Phosphatase↗