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Biomedical subjects

T Q Nguyen

Publications and source records attributed to T Q Nguyen.

At least 19 recordsLinked to original sources
PubMed2001

Acute management of dengue shock syndrome: a randomized double-blind comparison of 4 intravenous fluid regimens in the first hour.

Dengue hemorrhagic fever is an important cause of morbidity among Asian children, and the more severe dengue shock syndrome (DSS) causes a significant number of childhood deaths. DSS is characterized by a massive increase in systemic capillary permeability with consequent hypovolemia. Fluid resuscitation is critical, but as yet there have been no large trials to determine the optimal fluid regimen. We undertook a randomized blinded comparison of 4 fluids (dextran, gelatin, lactated Ringer's, and "normal" saline) for initial resuscitation of 230 Vietnamese children with DSS. All the children survived, and there was no clear advantage to using any of the 4 fluids, but the longest recovery times occurred in the lactated Ringer's group. The most significant factor determining clinical response was the pulse pressure at presentation. A comparison of the colloid and crystalloid groups suggested benefits in children presenting with lower pulse pressures who received one of the colloids. Further large-scale studies, stratified for admission pulse pressure, are indicated.

Adolescent↗
PubMed2001

Increased expression of HDJ-2 (hsp40) in carotid artery atherosclerosis: a novel heat shock protein associated with luminal stenosis and plaque ulceration.

PURPOSE: Evidence suggests that both humoral and cellular autoimmune processes directed toward heat shock proteins (hsp) contribute to the pathogenesis of atherosclerosis. We characterized a human hsp distinct from those previously characterized in atherosclerotic lesions, termed HDJ-2. METHODS: To determine the role of HDJ-2 in atherosclerosis, we compared the level of HDJ-2 mRNA expression with the level of hsp60 and hsp70 mRNA expression in 26 carotid endarterectomy specimens and 17 normal arteries. The level of expression of HDJ-2 mRNA was also correlated to the presence of plaque ulceration and the degree of luminal stenosis associated with the lesion. RESULTS: The expression of HDJ-2 and hsp70 was significantly higher in carotid artery plaques as compared with normal arteries: HDJ-2, 6.7 +/- 1.6 vs 0.1 +/- 0.04, (P =.001); hsp70, 9.5 +/- 0.9 vs 3.7 +/- 0.8, (P =.002). There was no significant difference in hsp60 expression between carotid artery plaques and normal arteries (21.0 +/- 0.9 vs 20.6 +/- 0.8, P =.65). Increased HDJ-2 expression in carotid artery plaques was independent of hsp70 (Pearson correlation, r = 0.11; Bartlett chi(2) analysis, P =.71). Within the ulcerated plaque group, there was a correlation between degree of stenosis and high HDJ-2 mRNA expression (r = 0.896, P =.016). However, there was no correlation between degree of stenosis and high HDJ-2 mRNA expression within the nonulcerated plaque group (r = 0.530, P =.076) or within the entire group of patients (r = 0.0085, P =.97). CONCLUSION: These results demonstrate that expression of HDJ-2 is significantly increased in atherosclerotic carotid artery plaques as compared with hsp60 and hsp70 and correlates with luminal stenosis in ulcerated atherosclerotic carotid artery plaques.

Arteriosclerosis↗
PubMed2001

So much for keeping secrets: the importance of considering patients' perspectives on maintaining confidentiality.

Little data are available from patients' perspectives regarding the maintenance of confidentiality by care providers. Such data may be useful in determining the importance of confidentiality to patients and in developing appropriate policies and procedures regarding confidentiality. Three focus groups were conducted with support groups of rural HIV-positive patients. Text was coded inductively and analyzed with software designed for qualitative analysis. Participants perceived breaches of confidentiality in hospitals, clinics and health departments that occurred by word of mouth, computers, facsimile and written materials. Patients included sharing stigmatizing medical information among medical providers without prior consent as a breach. They made decisions about where to seek care based on the degree of professionalism of medical staff (which included respecting confidentiality), clinic location or the level of security of the organization's computer network since they believed that computers increase information access. Finally, participants believed that medical personnel should be taught the importance of maintaining confidentiality and that those who violated confidentiality should be punished. Patients would like confidentiality policies that require providers to: (1) explain procedures for sharing information, (2) request patients' specific consent for access to their medical records, even among other providers, and (3) punish those who breach confidentiality.

Attitude↗
PubMed2001

Characteristics of individuals infected with the human immunodeficiency virus and provider interaction in the predominantly rural Southeast.

BACKGROUND: This detailed study describes the demographic characteristics, behavioral characteristics, care-seeking behavior, and barriers to health care and social services for patients infected with the human immunodeficiency virus (HIV) in the Southeast. METHODS: We conducted a cross-sectional study of Medicaid-eligible HIV-positive individuals (chart abstractions [N = 679], patient surveys [N = 487]) and care providers (N = 101) in North Carolina. Relative risks compare blacks, women, and respondents reporting substance abuse with their reference groups. Results are compared with those of a larger sample including persons from Alabama and South Carolina. RESULTS: Forty-one percent of respondents did not receive care locally, and 69% of female respondents had young children at home. In the 12 months before the survey, 66% reported substance abuse; 49% reported multiple living situations; 11% had entered drug treatment; and 10% had difficulty with the law. The findings in North Carolina did not differ from those in Alabama and South Carolina. Mean indices from care provider surveys revealed low interagency knowledge and referrals. CONCLUSIONS: Patients have complex needs for both social services and health care. However, providers are not working together.

Adult↗
PubMed2000

Dorzolamide and corneal recovery from edema in patients with glaucoma or ocular hypertension.

PURPOSE: To investigate whether dorzolamide alters corneal hydration control in patients with glaucoma or ocular hypertension. METHODS: Pachymetry, tonometry, and endothelial cell density were measured by a masked observer in 19 subjects with bilateral glaucoma or ocular hypertension. They were treated with 2% dorzolamide in one eye, and with saline in the other, before wearing contact lenses under patched eyes. Corneal thickness, measured each 30 minutes up to 4.5 hours after contact lens removal, enabled estimation of percentage recovery per hour and time for 95% of corneal thickness recovery for both eyes. Seven patients repeated this test after 1 year of dorzolamide use, and their results were compared with those of the preceding year. RESULTS: After induction of hypoxic corneal edema, there was no significant difference between paired corneas in swelling levels (60.0+/-11.8 and 59.8+/-12.9 microm) (P = .94), time to 95% recovery (440.6+/-255.8 and 445.4+/-186.7 minutes) (P = .93), and percentage recovery per hour (38.1%+/-10.9% and 36.1%+/-9.6%) (P = .40). Subjects followed up after 1 year of dorzolamide use did not differ significantly in values of endothelial cell density, percentage recovery per hour, or time to 95% recovery from those obtained a year before. One subject developed persistent corneal edema after his stress test in the eye treated with dorzolamide. CONCLUSION: There is no significant difference in the recovery from induced corneal edema after either a short-term or 1-year use of dorzolamide in patients with glaucoma or ocular hypertension with a normal corneal endothelium. One patient had persistent corneal edema after the stress test was performed on the dorzolamide-treated eye.

Aged↗
PubMed2000

The C. elegans septin genes, unc-59 and unc-61, are required for normal postembryonic cytokineses and morphogenesis but have no essential function in embryogenesis.

Septins have been shown to play important roles in cytokinesis in diverse organisms ranging from yeast to mammals. In this study, we show that both the unc-59 and unc-61 loci encode Caenorhabditis elegans septins. Genomic database searches indicate that unc-59 and unc-61 are probably the only septin genes in the C. elegans genome. UNC-59 and UNC-61 localize to the leading edge of cleavage furrows and eventually reside at the midbody. Analysis of unc-59 and unc-61 mutants revealed that each septin requires the presence of the other for localization to the cytokinetic furrow. Surprisingly, unc-59 and unc-61 mutants generally have normal embryonic development; however, defects were observed in post-embryonic development affecting the morphogenesis of the vulva, male tail, gonad, and sensory neurons. These defects can be at least partially attributed to failures in post-embryonic cytokineses although our data also suggest other possible roles for septins. unc-59 and unc-61 double mutants show similar defects to each of the single mutants.

Amino Acid Sequence↗
PubMed1999

Structural requirements for polymeric immunoglobulin assembly and association with J chain.

Both IgM and IgA exist as polymeric immunoglobulins. IgM is assembled into pentamers with J chain and hexamers lacking J chain. In contrast, polymeric IgA exists mostly as dimers with J chain. Both IgM and IgA possess an 18-amino acid extension of the C terminus (the tail-piece (tp)) that participates in polymerization through a penultimate cysteine residue. The IgM (mutp) and IgA (alphatp) tail-pieces differ at seven amino acid positions. However, the tail-pieces by themselves do not determine the extent of polymerization. We now show that the restriction of polymerization to dimers requires both C(alpha)3 and alphatp and that more efficient dimer assembly occurs when C(alpha)2 is also present; the dimers contain J chain. Formation of pentamers containing J chain requires C(mu)3, C(mu)4, and the mutp. IgM-alphatp is present mainly as hexamers lacking J chain, and mumugammamu-utp forms tetramers and hexamers lacking J chain, whereas IgA-mutp is present as high order polymers containing J chain. In addition, there is heterogeneous processing of the N-linked carbohydrate on IgA-mutp, with some remaining in the high mannose state. These data suggest that in addition to the tail-piece, structural motifs in the constant region domains are critical for polymer assembly and J chain incorporation.

Amino Acid Sequence↗
PubMed1999

[Hepatectomy in intrahepatic lithiasis].

STUDY AIM: The aim of this study was to report the immediate results of a series of 65 hepatic resections for hepatolithiasis performed in Vietnam. PATIENTS AND METHOD: From 1986 to 1998, 44 men and 21 women (mean age: 40 years) underwent hepatic resection for hepatolithiasis. Fourty patients had previously undergone one or several operations for hepatolithiasis. The procedure was performed on emergency in 25 patients. Indications for hepatic resection were: angiocholitis and liver abscess in 22 cases, stones closely inserted in the biliary duct in 20 cases, hemobilia in 12 cases, stones located above a biliary stricture in 8 cases and stones associated with a postoperative biliary fistula in 3 cases. Liver resections (minor in 61 patients, including 55 left lobectomies, and major in 4 patients) were performed through transhepatic approach according to the Ton That Tung technique and followed by an external biliary drainage with a Kehr tube. RESULTS: There were 6 postoperative deaths (9%), 3 due to septic shock, 2 to cachexia, and 1 to liver failure. The 15 patients with complications recovered with conservative therapy. Bile infection was present in 93%, mostly with Escherichia coli and Enterobacter. Pigmented stones were usually found. CONCLUSION: Vietnam is a country with high incidence of hepatolithlasis. Hepatic resection is an adequate treatment for localized intrahepatic bile duct stones when the involved segment including biliary strictures and calculi can be completely removed. The procedure may be performed on emergency for liver abscess, or hemobilia.

Adult↗
PubMed1999

ECG beat detection using filter banks.

We have designed a multirate digital signal processing algorithm to detect heart beats in the electrocardiogram (ECG). The algorithm incorporates a filter bank (FB) which decomposes the ECG into subbands with uniform frequency bandwidths. The FB-based algorithm enables independent time and frequency analysis to be performed on a signal. Features computed from a set of the subbands and a heuristic detection strategy are used to fuse decisions from multiple one-channel beat detection algorithms. The overall beat detection algorithm has a sensitivity of 99.59% and a positive predictivity of 99.56% against the MIT/BIH database. Furthermore this is a real-time algorithm since its beat detection latency is minimal. The FB-based beat detection algorithm also inherently lends itself to a computationally efficient structure since the detection logic operates at the subband rate. The FB-based structure is potentially useful for performing multiple ECG processing tasks using one set of preprocessing filters.

Algorithms↗
PubMed1998

The relationship between parasite counts, lesions, antibody titres and daily weight gains in Psoroptes ovis infested cattle.

Psoroptes ovis counts, extent of lesions (clinical index: ClinI), daily weight gains (DWGs) and anti-P. cuniculi antibody titres in ELISA were recorded during seven therapeutic field trials. Relationship between these different data were studied. The differences between the mean DWG of treated and untreated control animals of the different trials ranged from 39 to 1206 g/day. Data were pooled for statistical analysis and the influence of trial conditions (management of the herd, farm, treatment) was extracted from each individual data by subtracting, from the DWG of each animal, the mean DWG of its trial. Such data were called daily weight gain over the trial mean (DWG/TM). Multiple regression of DWG/TM, calculated over the period between the clinical examinations in control animals (n = 40), on clinical indices and sex demonstrated a significant DWG/TM reduction per percentage of affected body surface according to the following equation: DWG/TM (in g/day)= 135-22 ClinI(0)-13 ClinI(28/35)-70 (if male) (R2 adjusted = 0.39), where ClinI(0) and ClinI(28/35) are the clinical indices recorded respectively at the beginning (day 0) and at the end (day 28 or 35) of the experimental period during which the animals were left untreated. A nonsignificant relationship (R2 adjusted = 0.07) was found between the antibody titres on day 28 or 35 and the individual DWG/TM This would suggest that serology could be used to estimate the prevalence of the disease on a local or national basis but not to calculate its economic impact.

Animals↗
PubMed1998

4-Aminoquinoline antimalarials enhance UV-B induced c-jun transcriptional activation.

Previous work has documented that the earliest observable response in mammalian cells following ultraviolet (UV) irradiation is the activation of plasma membrane-associated Src tyrosine kinases. These molecules then trigger a signalling cascade that results in activation of the transcription factor AP-1 which subsequently transactivates the early immediate genes including c-jun. This pathway has been postulated to play a protective role against UV damage. As aminoquinoline antimalarials such as chloroquine are known to downregulate several photoinduced cutaneous disorders including LE-specific skin disease, we asked whether chloroquine might be capable of modulating this early limb of the UV light response. A431 cells (a human epidermal keratinocyte cell line) that had been transfected with a c-jun luciferase reporter gene construct were then treated with physiologically relevant concentrations of chloroquine followed by exposure to 0-125 J/m2 of UV-B from a bank of unfiltered FS20 lamps. Chloroquine pretreatment resulted in a dose-dependent increase in luciferase activity in permanently transfected A431 cells (luciferase activity was increased by 45% at 2.5 x 10(-5) M chloroquine and 125 J/m2 of UV-B). Hydroxychloroquine pretreatment also resulted in an increase in luciferase activity. Primaquine, an 8-aminoquinoline, did not influence the UV-B induced c-jun activity. Furthermore, chloroquine did not have a similar impact on HSP-70 gene activity during heat shock. These studies suggest that the beneficial effect of the 4-aminoquinoline antimalarials in various photodermatoses including cutaneous LE might result in part from the capacity of these drugs to enhance the protective early limb of the UV response.

Aminoquinolines↗
PubMed1998

Humoral and cell-mediated immune responses of beef and dairy cattle experimentally infested with Psoroptes ovis.

OBJECTIVE: To compare cellular and humoral immune responses of beef (Belgian White and Blue [BWB]) and dairy (Friesian-Holstein [FH]) cattle to Psoroptes ovis infestation and to determine whether P ovis infestation impaired immune responses to infectious bovine rhinotracheitis virus (IBR) vaccine or an immunogenic protein (keyhole-limpet hemocyanin [KLH]). ANIMALS: 19 BWB and 6 FH 1-year-old calves. PROCEDURE: 2 trials were performed. In each trial, 7 (trial 1) or 6 (trial 2) BWB calves and 3 FH calves were experimentally infested with P ovis and 3 BWB calves were maintained as uninfested controls. Animals were inoculated with KLH and IBR virus vaccine twice; 3 BWB calves in each trial were treated with ivermectin. Serum antibody responses to KLH, IBR virus, and P ovis were measured by use of ELISA. A lymphocyte transformation assay was used to determine nonspecific responses to 3 mitogens and specific lymphocyte reactivity to P ovis antigen. RESULTS: In each trial, 3 BWB and 3 FH calves developed clinical signs of psoroptic mange and mites could be recovered. Infested and control animals developed similar antibody titers to KLH and IBR virus. Antibodies to P ovis were detected early in some infested calves, and this was correlated with a marked cell-mediated immune response. Lymphocyte responsiveness to the 3 mitogens was not significantly different among groups. CONCLUSIONS: In these calves, infestation with P ovis induced a marked humoral and cell-mediated immune response. Immunosuppression was not evident.

Animals↗
PubMed1997

Efficacy of pour-on and injectable formulations of moxidectin and ivermectin in cattle naturally infected with Psoroptes ovis: parasitological, clinical and serological data.

On the basis of Psoroptes ovis counts performed on day -7, 32 animals were randomly allocated to a control group of five animals or to four groups comprising six or seven animals which were treated, respectively, with pour-on ivermectin (IPO), injectable ivermectin (II), pour-on moxidectin (MPO) and injectable moxidectin (IM). Living mites were counted in skin scrapings on days 0, 7, 14, 28, 42 and 56 post-treatment (PT). Lesions were recorded on a standardized map on days 0 and 56 PT. Antibody kinetics were studied using ELISA on serially diluted sera. The antibody titres were expressed as the dilution giving the positive/negative cut-off. Until their treatment on day 28, the control animals remained parasitologically positive and their antibody titres increased. In treated groups, all living mite counts were negative on days 28 and 42 PT but some animals were still infected on days 7 and 14 PT. On day 56, living P. ovis were found in one animal of the IPO group. An equation of regression describing the antibody decrease was calculated with each individual data set. In most of the treated animals, the coefficient of determination R2, which describes the closeness of fit to the linear model, was above 0.9. The linear model could not be applied (low R2) to the antibody kinetics of four animals: the day 56 positive animal and its two neighbours in the IPO group and one animal from the MPO group. In the treated groups, the differences between the numbers of infected animals, the mean daily weight gains or the mean antibody titres were not statistically significant. Mean daily weight gains of the treated groups were higher than in control animals.

Animals↗
PubMed1997

Validation of French-language versions of the Visual Functioning Index (VF-14) and the Cataract Symptom Score.

OBJECTIVE: To produce and validate French-language versions of the Visual Functioning Index (VF-14), the Cataract Symptom Score (CSS) and two global measures of trouble and satisfaction with vision. DESIGN: Survey by means of telephone interviews conducted 2 weeks apart. SETTING: Ophthalmology clinic of a teaching hospital in Montreal. SUBJECTS: Subjects were recruited among patients with ocular media opacities, such as cataracts and corneal opacities. Of the 71 subjects recruited, 66 (41 French-speaking and 25 French- and English-speaking) completed the study. OUTCOME MEASURES: Visual acuity, scores on vision-related questionnaires and on the 36-Item Short-Form Health Survey (SF-36), a measure of perceived health status. RESULTS: The integral consistency of the French-language versions of the VF-14 and the CSS was high, with Cronbach alpha values of 0.96 and 0.82 respectively. The fidelity with regard to the English-language version, the test-retest reproducibility and the interrater agreement were high (intraclass correlation coefficients > or = 0.80). The correlation between the visual acuity of the better eye and the mean score on all four vision-related measures was statistically significant (p < or = 0.05). The VF-14 scores were also correlated with the score on five of the eight SF-36 subscales (p < or = 0.05). CONCLUSIONS: Our results show that French-language versions of the VF-14, CSS and global measures of trouble and satisfaction with vision are reliable and valid.

Adult↗
PubMed1996

A sandwich enzyme-linked immunosorbent assay to study the antibody response against Psoroptes ovis in cattle.

A sandwich enzyme-linked immunosorbent assay (ELISA) was developed using polyclonal antibodies from Psoroptes cuniculi infested rabbit and a crude P. cuniculi antigen. Sera from 133 Psoroptes ovis infested and 137 uninfested cattle were serially diluted from 1:100 to 1:102,400 and analyzed. Curves obtained by plotting log dilution versus optical densities (OD) were used and a working dilution of 1:400 was selected. Positive/negative cut-off values were calculated using the mean OD percentage (6%) of all negative sera plus 3 standard deviations. Sensitivity and specificity according to the resulting cut-off (25%) were 98.5% and 97.8% respectively. Expressed as the dilution giving the cut-off value, results in ELISA revealed a wide range of antibody titres (from 1:19 up to 1:2,240,000) with a geometric mean value of 1:35,480, and this is probably related to the well-described hyperglobulinemia in P. ovis infestations. In two trials performed at a 1 year interval, 19 Belgian White and Blue and six Fresian-Holstein calves were experimentally infested, and sensitivity and specificity were calculated throughout the experimental period. Sensitivity reached 78% on day 70 in trial 1 and 100% on day 49 in trial 2 (sensitivity was calculated using data from three control animals, three infected Fresian-Holstein animals and seven (trial 1) or six (trial 2) infected Belgian White and Blue animals). Specificity on day 0 was 100% in trial 1 and 92% in trial 2. At the end of both trials, specificity decreased in 80%. The development of the serum antibody activity to Psoroptes antigens was correlated with the development of lesions: in trial 1, the coefficient of correlation between the percentage of body surface with lesions and antibody titre was 0.82 (probability of no relationship P < 0.005) on day 56 post-infection (PI) and in trial 2, 0.83 (P < 0.025) and 0.87 (P < 0.025) on days 35 and 63 PI respectively.

Animals↗
PubMed1996

Calreticulin binds hYRNA and the 52-kDa polypeptide component of the Ro/SS-A ribonucleoprotein autoantigen.

Calreticulin (CR) is a multifunctional, calcium-binding protein that has recently been shown to bind to and promote the replication of the rubella virus genome in mammalian cells. While CR is now widely recognized as a new human autoantigen, the relationship between CR and the Ro/SS-A ribonucleo-protein (RNP) autoantigen has been somewhat controversial. In this work, we demonstrate that unphosphorylated human rCR binds specifically and distinctly to in vitro transcribed forms of hYRNA, the RNA backbone of the Ro/SS-A RNP particle. This interaction appears to be mediated by binding through the N- and C-terminal domains of CR, but not by the central proline-rich domain. Furthermore, our studies indicate that CR can facilitate the binding of the 60-kDa polypeptide component of the Ro/SS-A RNP (Ro60) to hYRNA. In addition, CR and the 52-kDa Ro/SS-A polypeptide (Ro52) appear to be capable of interacting through direct protein-protein binding. These studies confirm that CR is an hYRNA-binding protein, and provide for the first time a molecular mechanism by which Ro52 can be linked physically to hYRNA. Through these molecular interactions and its known functional role as a chaperone, it is suggested that CR plays a supportive role in the formation of the Ro/SS-A RNP complex. The capacity of CR to interact with RNA viruses such as rubella provides an additional argument for an infectious trigger for autoantibody production against self RNP particles such as Ro/SS-A.

Autoantigens↗
PubMed1995

The safety of orotracheal intubation in patients with unstable cervical spine fracture or high spinal cord injury.

BACKGROUND: The potential merits and dangers of orotracheal and nasotracheal intubation in patients with injury to the cervical spine or spinal cord continue to be debated. To address this issue, a prospective study was conducted at a level 1 trauma center in patients with respiratory embarrassment and either or both of these injuries. MATERIALS AND METHODS: Over a 7-year period, all such patients underwent neurologic examination by a trauma surgeon on arrival at the trauma center, immediately after endotracheal intubation, and at frequent intervals throughout hospitalization. Cervical immobilization was maintained manually during endotracheal intubation. When necessary, patients were sedated or paralyzed with short-acting pharmacologic agents. RESULTS: During the study period, there were 81 patients with 98 cervical vertebral body fractures, but without evidence of spinal cord injury on initial examination. Sixty-seven patients (83%) were legally intoxicated, and 12 patients had closed head injury. Endotracheal intubation was performed in 26 patients with unstable fractures, and 22 patients were intubated via the oral route. No patient manifested a subsequent neurologic deficit. Sixty-nine additional patients presented with high spinal cord injury; 16 had no cervical spine fracture, and 53 patients had 61 fractures of the cervical vertebrae. Sixty patients (87%) were intoxicated, and 8 patients had closed head injury. Endotracheal intubation was performed in 29 of these patients, and 26 patients were intubated via the oral route. No patient experienced further neurologic deficit following endotracheal intubation. CONCLUSION: In trauma victims with or at high risk of cervical spinal cord injury, orotracheal intubation is a rapid, safe means of achieving airway control.

Adult↗