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Biomedical subjects

A Nguyen

Publications and source records attributed to A Nguyen.

105 records · Page 6Linked to original sources
PubMed1987

Leukotriene C4 binding sites in mouse brain: pharmacological characteristics.

The binding sites for [3H]leukotriene C4 were studied in membrane preparations of mouse brain and liver. Isotherm binding analysis revealed one binding site with a Kd of 10.39 +/- 1.97 nM (Scatchard) or 10.15 +/- 1.00 nM (non-linear). The maximal binding capacity (Bmax) was 49.20 +/- 3.80 (Scatchard) or 48.50 +/- 2.63 (non-linear) pmol/mg prot. Specific binding represented more than 90% of the total binding. In displacement reactions on brain membranes, LTC4 was 100 times more active than LTD4, which displayed 10 times the activity of GSH. Glutamic acid, bilirubin and hematin were inactive. The activity of LTC4 was slightly less on liver membranes than on brain membranes. Liver sites had some affinity for GSH but not for LTD4 bilirubin or hematin. The results support the hypothesis that LTC4 and its receptor may have a neuromodulatory function.

Animals↗
PubMed1985

[Peroperative echocardiography in cardiac surgery].

Echocardiography is not only useful for pre-operative evaluation of cardiac lesions and to control the quality of some surgical procedures; used peroperatively, it contributes to our knowledge of cardiac function at different stages of the operation. It has taught us that the ischaemic cardiac arrest observed in cardiopulmonary bypass results in reduction of left ventricular compliance and that this can be prevented by potassium-induced cardioplegia. It has also shown that immediately after cardiac valve replacement, the left ventricular "pump" function is reduced in aortic and mitral regurgitation and increased in stenosis. In addition, it has provided evidence that closure of the pericardium and sternum is accompanied with a fall in left ventricular compliance and with disturbances in haemodynamics. The few post-operative studies reported have shown that end-expiratory positive pressure reduces the size of both right and left ventricular cavities. Per--and post--operative studies of left ventricular regional kinetics have not yet been carried out, but this seems to be a good field of application for trans-oesophageal echocardiography.

Cardiac Surgical Procedures↗
PubMed1985

Characteristics of pertechnetate movement across the canine tracheal epithelium.

Several 99mTechnetium-labeled markers have been used to study the barrier properties of the pulmonary epithelium; among these compounds is sodium pertechnetate (TcO4-). As TcO4- has pseudohalide properties, and as the characteristics of the movement of this ion across the airway epithelium are unknown, we examined its bidirectional permeability coefficients, and compared them with those of radiolabeled Cl- and mannitol in canine tracheal epithelium in vitro. We found that this ion behaves similarly to Cl- in its translocation across the airway epithelium.

Animals↗
PubMed1985

Facial profileplasty by liposuction extraction.

Facial profileplasty can include the removal of abnormal fat deposits in the face and neck as an individual begins to age and, in many cases, the correction of chin projection to achieve a better neck-chin contour line. In this report we retrospectively analyze the complications and results from 142 patients undergoing facial liposuction alone or in combination with chin augmentation or rhytidectomy during a follow-up period of 14 months. The liposuction technique offers very low morbidity and is superior to conventional excisional methods.

Adipose Tissue↗
PubMed1983

Construction and properties of an integrable plasmid for Bacillus subtilis.

A plasmid useful for locating the chromosomal site of cloned DNA fragments that lack intrinsic genetic activity, for insertional mutagenesis, for single-copy complementation, and for dominance studies was constructed. Some plasmids containing Bacillus subtilis DNA were only active in transformation when the tetracycline resistance determinant of the plasmid was inactivated. The results suggest that production of the tetracycline gene product is lethal to B. subtilis.

Bacillus subtilis↗
PubMedDate not supplied

A web-based database for diagnosis of haematologic neoplasms using immunophenotyping by flow cytometry.

The interpretation of immunophenotyping results by flow cytometry involves pattern recognition of different haematologic neoplasms that may have similar immunologic marker patterns. The numerous markers available in the flow cytometry laboratory make these patterns difficult to remember, especially for those of uncommon neoplasms. We describe the design and implementation of a Web-based database for diagnosis of haematologic neoplasms using results of immunophenotyping by flow cytometry. This database aims to assist pathology and haematology residents in interpreting flow cytometry data, and is designed to reach a wide base of users who use a variety of browsers on different computer platforms. Five modules are developed in this comprehensive program: (a) differential diagnosis: to generate a list of differential diagnoses that closely match the marker results in a given case; (b) display of disorders: typical results of markers for each disorder; (c) display of markers: relevant information of each immunologic marker; (d) display of archived cases for a disorder: marker results of cases previously diagnosed for a disorder; and (e) display of summary for archived cases: summary of marker results of all the archived cases for each disorder. Our experience with this Web-based database in teaching pathology residents has been very encouraging. Since the World Wide Web is increasingly more accessible to computer users, it has become an ideal medium for distribution of clinical decision-support software.

Antigens, CD↗
PubMedDate not supplied

Pivot design in bileaflet valves.

The design criteria leading to the development of a new bileaflet valve (Sorin Bicarbon) were derived from the analysis of functional requirements, the performance of existing prostheses, and the availability of an advanced carbon coating technology (Carbofilm). The hinge is the critical element affecting fluid dynamics, durability, and thrombus formation in bileaflet valves. A comparative study of three existing models led to a new hinge design that was based on coupling two spheric surfaces with different radii of curvature (leaflet pivot and hinge recess) and obtained by electroerosion into a Carbofilm-coated metallic housing. In this valve, the point of contact moves continuously by rolling, not sliding. This minimizes friction and wear and allows uninterrupted washing of the blood exposed surfaces even during diastole (a finding established in patients using transesophageal echocardiography). Tricuspid implantation without anticoagulation in 33 sheep did not lead to thrombotic events (follow-up, 40-400 days). In the first 36 clinical implants observed for 15 months (mitral position, size 29; two unrelated deaths), the mean diastolic gradient by echo Doppler was 4 +/- 1.25 mmHg; the functional area was 3.2 +/- 0.6 cm2. No leaflet fracture and no thrombotic or embolic complications were observed clinically using a standard anticoagulant regimen.

Adult↗
PubMedDate not supplied

Can statins reduce the inflammatory response to cardiopulmonary bypass? A clinical study.

OBJECTIVE: In addition to lowering lipid levels, statins might reduce leukocyte-endothelial cell interactions. Therefore, we assessed whether this effect could limit the inflammatory response to cardiopulmonary bypass (CPB) in cardiac surgical patients. METHODS: Twenty patients undergoing valve or coronary operations with tepid (34 degrees C) CPB were randomized to receive an oral dose of atorvastatin (40 mg the evening before and 40 mg the morning of surgery) or to serve as controls. Pre- and post-CPB blood samples were assayed for neutrophil CD11b surface adhesion molecule and oxidative burst. Plasma levels of interleukins 6 and 8, P-selectin, soluble intercellular adhesion molecule-1, and lactoferrin were measured by enzyme-linked immunosorbent assay (ELISA). In addition, right atrial biopsies were taken before and at the end of CPB, and processed for the expression of the transcription nuclear factor-kappa B (NF-kappaB). RESULTS: The two groups did not differ with regard to pre- and intraoperative data. Except for P-selectin, postbypass values of all markers significantly increased over baseline values, but atorvastatin therapy failed to attenuate the magnitude of this increase. In the two groups, the expression of NF-kappaB significantly (p = 0.004) increased over baseline without group effect. Postoperative clinical outcomes did not differ either between the two groups. CONCLUSION: These data show that acute preoperative statin therapy fails to limit the inflammatory response to CPB; however, the data also document a major upregulation of NF-kappaB during cardiac operations, thereby providing a sound rationale for interventions targeted at inactivating this key component of the inflammatory cascade.

Aged↗
PubMedDate not supplied

The effects of KN62, a Ca2+/calmodulin-dependent protein kinase II inhibitor, on adrenocortical cell aldosterone production.

The effects of KN62 on aldosterone secretion have been studied using an angiotensin II (AII)- and K(+)-responsive human adrenocortical tumor cell line (H295R). Basal aldosterone secretion (measured by RIA) was 0.57 +/- 0.22 pmol/mg protein.h. The physiologicial agonists AII (10 nM) and K+ (14 mM) increased aldosterone secretion by 6.9- and 5.0-fold, respectively. Aldosterone secretion was also stimulated by dibutyryl cyclic AMP (dbcAMP, 1 mM, 10.3-fold over basal). Nifedipine dose-dependently inhibited K(+)- and AII-stimulated aldosterone secretion. In contrast, dbcAMP-stimulated secretion was relatively insensitive to this agent (26.8% inhibition at 1 microM nifedipine). K(+)- and AII-stimulated aldosterone production was also dose-dependently inhibited by KN62, which produced 93.9% and 82.3% inhibition at 10 microM KN62 (both p < 0.01). In order to test the specificity of KN62 in H295R cells, its effects on various other steroidogenic agonists were assessed. KN62 dose-dependently inhibited aldosterone secretion stimulated by dbcAMP, 22-hydroxycholesterol and pregnenolone. In addition, KNO4, a derivative of KN62 which is not a potent inhibitor of CaM Kinase II, exhibited a similar pattern of inhibition. These data confirm the requirement for extracellular Ca2+ in the stimulation of human adrenocortical cell aldosterone secretion by AII and K+. However, the non-specific inhibitory effects of KN62 in H295R cells limit the usefulness of this agent as a tool for investigations of the involvement of CaM kinase II in adrenocortical steroidogenesis.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMedDate not supplied

Occupations and well-being: a study of personal projects.

OBJECTIVE: The purpose of this study was to explore the relationship between occupation and subjective well-being (SWB). METHOD: A convenience sample of 120 adults completed a personal projects analysis, a method of rating their current goal-directed pursuits. They also completed measures of SWB (Affect Balance Scale, Life Satisfaction Index Form A) and personality traits (Myers-Briggs Personality Inventory). Characteristics of personal projects were correlated with SWB scores. Multiple regression analysis was used to investigate possible predictors of well-being from among the characteristics of personal projects, personality traits, and demographic variables. RESULTS: The stress associated with personal projects was significantly and inversely correlated with well-being, as was project difficulty. Perceived progress in completing projects was significantly positively correlated with well-being. The strongest predictors for well-being were the composite project factors of stress and efficacy. Two personality traits, sensing and extraversion, interacted with the project dimension of stress to emerge as significant predictors of well-being. Together, these four variables explained 42% of the variance in well-being scores. CONCLUSION: These findings are consistent with assumptions that attributes of meaningful occupations are significantly related to people's perceived well-being.

Adult↗