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Biomedical subjects

D Tran

Publications and source records attributed to D Tran.

At least 37 records · Page 2Linked to original sources
PubMed2001

Expression of apoptosis-related proteins and structural features of cell death in explanted aortocoronary saphenous vein bypass grafts.

This study aimed to investigate the features of cell death occurring in aortocoronary saphenous vein bypass grafts. Human aortocoronary saphenous vein bypass grafts with angiographic luminal stenosis of > 75% were explanted from 14 patients at redo coronary artery bypass grafting. Proteins associated with apoptotic pathways were identified immunohistochemically using antibodies to Bcl-2, Fas, BAX, p53 and CPP32. Cells undergoing DNA fragmentation were identified by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). DNA synthesis was investigated using the antibody to proliferating cell nuclear antigen (PCNA). Ultrastructural features of cell death were examined by electron microscopy. Anti-apoptotic (Bcl-2) and pro-apoptotic (Bax, p53, CPP32 and Fas) proteins were expressed throughout the graft wall, but marked differences in the characteristics of cell death were noted between atherosclerotic and non-atherosclerotic areas of the intima. In atherosclerotic areas, pro-apoptotic proteins were widely expressed, but ultrastructural analysis failed to identify cells showing typical features of apoptosis. In these areas, necrotic cells were frequently observed, with negative correlation of Bcl-2 expression with TUNEL. Pro-apoptotic proteins showed no correlation with TUNEL. In contrast, in non-atherosclerotic areas of vein grafts, the expression of both anti-apoptotic (Bcl-2) and pro-apoptotic proteins (p53, Bax and CPP32) correlated with TUNEL. In atherosclerotic areas, non-atherosclerotic intimal areas, and in the underlying media, the numbers of TUNEL+ cells correlated with PCNA positivity. Ultrastructurally, apoptotic bodies and features of necrosis were observed in non-atherosclerotic areas of grafts. The present observations indicate that in atherosclerotic areas, cell death occurs mainly by necrosis, while in non-atherosclerotic areas, cell death occurs by both necrosis and apoptosis. An imbalance between DNA fragmentation and DNA synthesis may contribute to graft instability and failure.

Aged↗
PubMed2001

A retrospective review of PUVA therapy at the National Skin Centre of Singapore.

BACKGROUND: Photochemotherapy (PUVA) is beneficial for the treatment of various dermatoses. The introduction of ultraviolet B and narrow-band ultraviolet B phototherapy has had a significant impact on the role of PUVA in dermatology. This study aims to assess the current role of PUVA in treating dermatoses, in a predominantly Asian population, at the National Skin Centre in Singapore. MATERIALS AND METHODS: We reviewed the clinical data of 115 patients who were started on PUVA treatment at the National Skin Centre, Singapore in 1998. We analysed the epidemiology data, the clinical response rate and the adverse effects of PUVA therapy. All of the patients continued to have ongoing maintenance treatment. RESULTS: Most of our patients were Chinese (74.8%) and male (58.3%), ranging from the ages of 4 to 74 years. Vitiligo (60.9%) was the commonest skin disorder treated with PUVA, followed by psoriasis (20.9%), endogenous eczema (11.3%), mycosis fungoides (3.5%), lichen amyloidosis (2.6%) and prurigo nodularis (0.9%). Most of our patients received paint PUVA (50.4%), 33.9% oral PUVA and 15.7% bath PUVA. The best clinical response--those patients achieving a greater that 50% clearance--was observed in patients with endogenous eczema, psoriasis and mycosis fungoides (76.8%, 73.9% and 60%, respectively). Of the vitiliginous patients, 54.3% experienced a poor response to PUVA therapy. The main side effects were mild erythema and pruritus. CONCLUSION: PUVA remains a valuable, well-tolerated therapeutic option for a variety of dermatoses.

Adolescent↗
PubMed2001

Laboratory evaluation of mouthguard material.

The aim of this study was to evaluate, in vitro, the EVA material (polyvinylacetate-polyethylene copolymer) most commonly used in the fabrication of mouthguards and thus to help understand mouthguard performance and to improve mouthguard design. The material was tested for tensile strength, elongation, hardness and water absorption using specimens and tests described by the American Society for Testing and Materials Standards. Standard EVA sheets of 1, 2, 3 and 5 mm thickness were prepared. With increase in the thickness of the material, both the ultimate tensile strength and the elongation were decreased. The hardness and water absorption were unaffected. It was concluded that. overall, the thicker 5 mm EVA material was recommended for mouthguards as it displayed the least deformation to load and performed equally as well in the tests as other thicknesses.

Absorption↗
PubMed2001

The management of cutaneous leishmaniasis from Belize.

We report 20 patients who contracted cutaneous leishmaniasis in Central and South America, 18 of them in Belize. The diagnosis was confirmed by the polymerase chain reaction (PCR) in 79% of those tested; the corresponding figure for histology was 62%, touch smear 46%, and culture 11%. Results of PCR can be falsely positive, so treatment should not be based on PCR alone. Of the 20 cases 18 were healed 6 weeks after intravenous sodium stibogluconate 20 mg/kg per day for 20 days. We present a management protocol.

Adolescent↗
PubMed2001

Racial and ethnic colorectal cancer patterns affect the cost-effectiveness of colorectal cancer screening in the United States.

BACKGROUND & AIMS: Colorectal cancer screening beginning at age 50 is recommended for all Americans considered at "average" risk for the development of colorectal cancer. METHODS: We used 1988-1995 California Cancer Registry data to compare the cost-effectiveness of two 35-year colorectal cancer screening interventions among Asians, blacks, Latinos, and Whites. RESULTS: Average annual age-specific colorectal cancer incidence rates were highest in blacks and lowest in Latinos. Screening beginning at age 50 was most cost-effective in blacks and least cost-effective in Latinos (measured as dollars spent per year of life saved), using annual fecal occult blood testing (FOBT) combined with flexible sigmoidoscopy every 5 years and using colonoscopy every 10 years. A 35-year screening program beginning in blacks at age 42, whites at age 44, or Asians at age 46 was more cost-effective than screening Latinos beginning at age 50. CONCLUSIONS: Colorectal cancer screening programs beginning at age 50, using either FOBT and flexible sigmoidoscopy or colonoscopy in each racial or ethnic group, are within the $40,000-$60,000 per year of life saved upper cost limit considered acceptable for preventive strategies. Screening is most cost-effective in blacks because of high age-specific colorectal cancer incidence rates.

Adult↗
PubMed2001

Short-course versus conventional length antimicrobial therapy for uncomplicated lower urinary tract infections in children: a meta-analysis of 1279 patients.

OBJECTIVE: The objective was to compare the efficacies of single-dose, short-course (4 days or less), and standard course (5 days or greater) antimicrobial therapy for uncomplicated childhood cystitis. METHODS: Prospective, randomized, controlled trials comparing 4 days or less of therapy (short courses) with 5 days or more of therapy (conventional therapy) were included if all of the subjects were <18 years of age, the initial infection was documented by urine culture, at least 1 subsequent culture was obtained between 3 and 30 days of enrollment, and some attempt was made to separate upper tract from lower tract infection. Composite differences among treatment groups were compared with a fixed or random effects model, depending on the test for heterogeneity. RESULTS: Of the 517 citations identified by literature search, 37 were selected for detailed review, and 22 were included in the final meta-analysis. The overall difference in cure rates between short and conventional courses of therapy was significant (6.38%; 95% CI: 1.88% to 10.89%), favoring the conventional course. Similar results were obtained when only studies comparing the same agents in the short and conventional courses were included (7.92%; 95% CI: 2.09% to 13.8%). Short-course amoxicillin was inferior to conventional length course (difference in cure rate, 13%; 95% CI: 4% to 24%); no difference was found between short-course and conventional length courses of trimethoprim-sulfamethoxazole (difference in cure rate, 6.24%; 95% CI = -3.74% to 16.2%). CONCLUSIONS: We conclude that single-dose amoxicillin is inadequate therapy for uncomplicated cystitis of childhood. Three days of trimethoprim-sulfamethoxazole therapy appears to be as effective as conventional length courses of the drug.

Adolescent↗
PubMed2001

The effects of candesartan on vascular responses to angiotensin II and norepinephrine in normal volunteers.

The effects of chronic administration of candesartan, 16 mg once-daily, to normal volunteers on cardiovascular responses to angiotensin II (Ang II) and norepinephrine (NE) were examined. Fifteen healthy, non-smoking volunteers participated in a randomised, double-blind crossover study of two weeks of candesartan therapy, compared with two weeks of placebo. Blood pressure (BP) responses were measured to increasing infusion rates of intravenous Ang II and NE, along with forearm blood flow (FBF) responses into intra-brachial arterial Ang II, 2 and 24 hours after the last dose of candesartan or placebo. FBF responses to intra-brachial arterial NE were recorded approximately 2 hours following the final dose. Systolic and diastolic BP responses to intravenous infusions of Ang II during candesartan treatment were completely suppressed and significantly lower than during placebo treatment, 2 hours (candesartan 96+/-10/55+/-8 mmHg; placebo 105+/-5/64+/-8 mmHg) and 24 hours (candesartan 94+/-8/54+/-8 mmHg; placebo 103+/-7/64+/-7 mmHg) following the last dose. In contrast, FBF responses to intra-brachial arterial Ang II were significantly suppressed by candesartan compared with placebo in a subgroup of subjects 2 hours following the last dose (n=9), but not 24 hours after the last dose (n=8). FBF responses to NE were also suppressed by candesartan treatment 2 hours following the last dose, while BP responses to intravenous NE were unaltered. Chronic candesartan therapy, 16 mg once-daily effectively suppresses pressor responses to Ang II over the duration of the dosing interval.

Adult↗
PubMed2001

How water oxygenation level influences cadmium accumulation pattern in the Asiatic clam Corbicula fluminea: a laboratory and field study.

The level of O2 in water is highly variable in the aquatic environment and is a major ventilatory drive in all animals breathing water. Low O2 partial pressure (PO2) strongly stimulates ventilatory activity compared to air-equilibrated or O2-enriched water. We studied the influence of ventilatory activity on the bioaccumulation rate of Cd in the freshwater Asiatic clam Corbicula fluminea for PO2 ranging from 4 to 40 kPa (2-20 mg/L at 15 degrees C) during steady-state exposure to controlled concentrations of Cd of approximately 2 or 0.5 microg/L under both laboratory and field conditions. The concentration of Cd in the expired water and its apparent extraction coefficient (EwCd) from the ventilated water were calculated. Results show that a low PO2 strongly enhanced Cd bioaccumulation rate in the whole soft body and modified the distribution pattern and the relative burden in the organs. Whatever the water PO2, values for the concentration of Cd in the expired water remained close to the Cd concentration in the inspired water and EwCd varied from 2 to 12%. Because the field results conformed to the laboratory analysis, the suggestion is made that the influence of O2 on bioaccumulation patterns of metals in water-breathers should be classified as of primary importance.

Animals↗
PubMed2001

Suggestions for HER-2/neu testing in breast carcinoma, based on a comparison of immunohistochemistry and fluorescence in situ hybridisation.

The arrival of Herceptin (Trastuzumab), an antibody against the HER-2 oncogene found in a proportion of breast carcinomas and other carcinomas, has emphasised the need for a standardised technique for demonstrating overexpression of HER-2. We compared the Dako A485 antibody and Dako HercepTest kit (HT) on a series of 122 breast carcinomas. Fluorescence in situ hybridisation (FISH) (Vysis) was performed on all cases with positive or equivocal immunohistochemical results. The Dako A485 showed HER-2 overexpression in 53% of carcinomas, while the HT showed 21% positive (HT 2+ 8%, HT 3+ 13%) and 79% negative (HT 0 67%, HT 1+ 12%). FISH for HER-2 gene amplification on all the HT 1+ and HT 2+ cases was negative, whereas FISH analysis of all HT 3+ cases was positive, with the exception of one case which could not be analysed for technical reasons. When histological subtype was analysed, only grade 3 infiltrating duct carcinomas were FISH-positive, suggesting that histological grading and subtyping may be able to triage carcinomas suitable for HER-2 testing. We suggest that the HT or a similar standardised immunohistochemical study for HER-2 can be used to screen breast carcinomas. We then recommend FISH where the carcinoma is HT 2+. FISH may also be appropriate in high grade, HT 1+ carcinomas where there are doubts regarding optimal tissue fixation or block storage conditions.

Antibodies, Monoclonal↗
PubMed2000

From Bittner to Barr: a viral, diet and hormone breast cancer aetiology hypothesis.

It is hypothesized that the human homologue of the mouse mammary tumour virus (HHMMTV) and other viruses, such as human papillomavirus (HPV) and Epstein-Barr virus (EBV), act as cofactors with diet, oestrogens and other hormones in the initiation and promotion of some types of breast cancer in genetically susceptible women. It is further hypothesized that diet influences the risk of breast cancer, through its influence on oestrogen metabolism and that of other hormones, in combination with genetic and infectious agents.

Breast Neoplasms↗
PubMed2000

Mechanism of extracellular calcium regulation of intestinal epithelial tight junction permeability: role of cytoskeletal involvement.

Recent studies suggest that an abnormal increase in intestinal tight junction (TJ) permeability may be an important etiologic factor in number of diseases including Crohn's disease, NSAID-associated enteritis, and various infectious diarrheal syndromes. The intracellular processes involved in regulation of intestinal epithelial TJ permeability, however, remain poorly understood. In this study, we used cultured Caco-2 intestinal epithelial cells to examine the intracellular processes involved in extracellular Ca(++) modulation of intestinal epithelial monolayer TJ barrier. Incubation of the filter-grown Caco-2 intestinal monolayers in Ca(++)-free solution (CFS), consisting of modified Krebs-buffer solution containing 0 mM Ca(++) and 1 mM EGTA, resulted in a rapid drop in Caco-2 epithelial resistance and increase in epithelial permeability to paracellular markers mannitol and inulin, indicating an increase in TJ permeability. The increase in Caco-2 TJ permeability was rapidly reversed by the re-introduction of Ca(++) (1.8 mM) into the incubation medium. The CFS-induced increase in Caco-2 TJ permeability was associated with separation of the cytoplasmic and transmembrane TJ proteins, ZO-1 and occludin, and formation of large intercellular openings between the adjoining cells. The CFS-induced modulation of TJ barrier was associated with activation of myosin light chain kinase (MLCK) activity and centripetal retraction of peri-junctional actin and myosin filaments. The inhibition of CFS-induced activation of Caco-2 MLCK with MLCK inhibitor (ML-7) prevented the CFS-induced retraction of actin and myosin filaments and the subsequent alteration of TJ barrier function and structure. Our results suggested that the CFS-induced alteration of TJ proteins and functional increase in TJ permeability was mediated by Caco-2 MLCK activation and the resultant contraction of the peri-junctionally located actin-myosin filaments. Consistent with the role of MLCK in this process, selected inhibitors of Mg(++)-myosin ATPase and metabolic energy, but not protein synthesis inhibitors, also prevented the CFS-induced retraction of actin and myosin filaments and the subsequent increase in TJ permeability. In conclusion, our results indicate that extracellular Ca(++) is crucial for the maintenance of intestinal epithelial TJ barrier function. The removal of extracellular Ca(++) from the incubation medium causes activation of Caco-2 MLCK, which in turn leads to an increase in intestinal monolayer TJ permeability.

Actins↗
PubMed2000

Electronic versus paper instruments for daily data collection.

PURPOSE: Collecting daily information on a series of similar, recurring events such as menstrual bleeding, headaches, or insulin levels using paper instruments is subject to problems such as missing or incorrectly recorded data, and retrospective data entry. The authors are developing and evaluating electronic data collection using hand-held personal computers (H/PC) for a variety of health-related applications, including tracking premenstrual syndrome (PMS), fertility awareness, and headaches, to improve accuracy and timeliness of data collection.METHODS: ProCycle is a prototype electronic diary for collection of daily data on menstrual bleeding, medications, and health symptoms. In a 3-month pilot test in 25 regularly cycling women, we compared its performance with a paper calendar regarding missing and incorrect data, data entry lag, data cleaning time, and users' preferences with respect to factors such as remembering to enter data, convenience, and overall preference. Additional programs for PMS, fertility, and headaches are being field tested on subjects from the Boston and New York areas, comparing performance with paper versions.RESULTS: In the pilot test, missing data occurred less frequently with ProCycle than with paper, particularly for any days with missing symptoms (4% vs. 35%, p < 0.05). ProCycle did not permit any data recording mistakes such as circling contradictory responses (e.g., bleeding and no bleeding), compared with incorrect data on 13% of paper calendars. Data entry/cleaning time was 81% lower for ProCycle. 70% of users preferred ProCycle overall, compared with 9% preferring paper (p < 0.01).CONCLUSIONS: Although the initial cost of the H/PC is significantly higher than paper, there are no recurring charges for printing or data entry, and data cleaning is minimal. Electronic instruments on an H/PC provide an efficient, accurate method of data collection, applicable to a number of areas of health-related research involving daily data collection.

Journal Article↗
PubMed2000

Formation and characterization of a single Trp-Trp cross-link in indolicidin that confers protease stability without altering antimicrobial activity.

Indolicidin is a 13-residue cationic, antimicrobial peptide-amide isolated from the cytoplasmic granules of bovine neutrophils. The unique composition of indolicidin distinguishes it from alpha-helical and beta-structured cationic peptides, because five of indolicidin's 13 residues are tryptophans: H-Ile-Leu-Pro-Trp-Lys-Trp-Pro-Trp-Trp-Pro-Trp-Arg-Arg-NH(2). Solid phase synthesis of indolicidin gave rise to a minor byproduct that possessed unusual fluorescence and UV absorbance properties compared with authentic indolicidin. The byproduct was purified by combined ion exchange and reversed phase high pressure liquid chromatography steps and was shown be identical to authentic indolicidin in its microbicidal activity against Staphylococcus aureus, Escherichia coli, Candida albicans, and Cryptococcus neoformans. Mass analysis of the byproduct revealed a 2-atomic mass unit reduction compared with indolicidin, suggesting the deprotonation of two indole side chains to form an intrachain delta(1),delta(1)'-ditryptophan derivative. We confirmed the nature of the cross-linked byproduct, termed X-indolicidin, by absorbance and fluorescence spectroscopy, peptide mapping, and sequence analysis. Edman degradation revealed that Trp-6 and Trp-9 were covalently cross-linked. Compared with indolicidin, X-indolicidin was partially resistant to digestion with trypsin and chymotrypsin, suggesting that the ditryptophan stabilizes a subset of molecular conformations that are protease resistant but that are absent in the native structure.

Amino Acid Sequence↗
PubMed2000

Use of a supermarket shelf-labeling program to educate a predominately minority community about foods that promote heart health.

OBJECTIVE: The purpose of this study was to evaluate the awareness and use of a supermarket-shelf labeling program designed to encourage shoppers to make food choices that promote heart health. DESIGN: A shelf-labeling program was implemented in 18 supermarkets serving minority communities in Detroit, Mich. Customers were given an exit survey to determine awareness and use of the program. SUBJECTS/SETTING: Three hundred sixty-one subjects were sampled. Sixty-six percent of the sample was female, 67% African-American, and the sample population had a mean age of 51.6 years +/- 18.5 SD. RESULTS: Overall awareness of the program was 28.8%. Awareness among minorities was significantly higher when compared with whites (35.3% vs 20.8%; P = .02). Gender, age, and education level were not predictive of program awareness but people screened for cardiovascular disease risk factors (elevated low-density lipoprotein or total cholesterol levels and/or elevated blood pressure) in the previous year had greater awareness than those not screened (32.6% vs 13.6%, P = .06). Use of the program was 56% among subjects aware of the program. This did not differ significantly by gender, age, or ethnicity. STATISTICAL ANALYSIS: Awareness and use were evaluated with respect to ethnicity, gender, education, race, age, and previous screening history. For purposes of analysis, African-American, Hispanic, and Asian-American respondents were combined into one group called "all minorities." The other group of respondents was called "whites." Between-group differences in categorical variables were analyzed using a chi 2 statistic. CONCLUSIONS: Awareness of the shelf-labeling program was modest, but highest among African-Americans. Subjects recently screened for cardiovascular disease risk had greater program awareness. This difference was not statistically significant. Use was relatively high among those aware of the program, suggesting that shelf labels have the potential to increase the selection of foods that promote heart health in predominately low-income, minority populations.

Adult↗
PubMed2000

Permanent alopecia following chemotherapy and bone marrow transplantation.

Alopecia can be a psychologically daunting prospect for people requiring cancer chemotherapy. Fortunately, most patients experience only temporary hair loss. We report the case of a 23-year-old woman with chronic myeloid leukaemia who developed permanent, near-total alopecia of her scalp, eyebrows, eyelashes, axillary and public hair following busulphan and cyclophosphamide chemotherapy which was used as conditioning prior to allogeneic bone marrow transplantation. The histology from a scalp biopsy revealed hair follicle destruction. Topical minoxidil failed to induce significant re-growth.

Adult↗
PubMed2000

Prevalence of Helicobacter pylori infection in 160 patients with Barrett's oesophagus or Barrett's adenocarcinoma.

BACKGROUND: The role of Helicobacter pylori infection in the development of Barrett's oesophagus and its complications is uncertain. The aim of the present study was to determine the importance of H. pylori infection in this disease by comparing the frequency of oesophageal and gastric H. pylori infection in a group of patients with Barrett's oesophagus or adenocarcinoma, with the frequency of infection in a control group without Barrett's disease. METHODS: The study group included 160 patients (123 male, 37 female; mean age: 61.2 years) who were classified (according to the highest grade pathological lesion in the oesophagus) as having Barrett's intestinal metaplasia (IM; 88 patients), Barrett's oesophagus with low-grade dysplasia (LGD; 28 patients), high-grade dysplasia (HGD; five patients), Barrett's indefinite for dysplasia (n = 4), and Barrett's adenocarcinoma (33 patients). A total of 91 of these patients had gastric antral specimens available for study. The control group consisted of 214 consecutive, prospectively enrolled symptomatic patients (122 male, 92 female; mean age: 57.2 years) who underwent upper gastrointestinal endoscopy and in whom Barrett's oesophagus or Barrett's adenocarcinoma was not found. A modified Warthin-Starry method was used to detect H. pylori infection. RESULTS: Oesophageal H. pylori infection was found in eight of 160 (5%) patients with Barrett's oesophagus or Barrett's adenocarcinoma. Holicobacter pylori organisms in the oesophagus were found only on non-intestinalized cardiac or oxyntocardiac mucosa. All patients with oesophageal H. pylori infection and an antral biopsy available for study had antral H. pylori infection. Gastric antral H. pylori infection was significantly less prevalent in patients in the Barrett's study group (15/91, 16.5%) than in the non-Barrett's control group (67/214, 31.3%; Fisher's exact test, P = 0.01). Patients from the control group with an endoscopic diagnosis of duodenal ulcer, gastric ulcer, gastritis, or duodenitis had a significantly higher prevalence of infection compared with the Barrett's group, but there was no difference in the infection prevalence in patients in the Barrett's group and patients with reflux oesophagitis, hiatal hernia, no endoscopic abnormality, or any other diagnosis. CONCLUSIONS: Oesophageal H. pylori infection is uncommon in patients with Barrett's IM, dysplasia, or adenocarcinoma, and may be restricted to non-intestinalized columnar epithelium. Gastric H. pylori infection may have a protective effect for the development of Barrett's oesophagus.

Adenocarcinoma↗
PubMed2000

Hematoxylin and safranin O staining of frozen sections.

Currently the hematoxylin and eosin staining procedure is the most popular among Mohs surgeons for histology. However, safranin O, a cheaper and relatively safer stain which is predominantly used for plant histology, should be considered as it offers similar or improved accuracy in the diagnosis of frozen sections of basal and squamous cell carcinomas.

Basal Cell Carcinoma↗