Autotransfusion of shed mediastinal blood in cardiac surgery.
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Aspartate Aminotransferases↗
Biomedical subjects
D Nguyen
Publications and source records attributed to D Nguyen.
A diagnostic workstation for neoplastic bone marrow diseases: evaluation on 526 cases.
The diagnostic accuracy of a workstation for neoplastic bone marrow pathology was evaluated on 526 cases from two institutions. The workstation consists of knowledge-based systems for peripheral blood analysis, flow cytometry immunophenotyping, and bone marrow morphology, linked together by a relational database. The "gold standard" diagnosis was established by complete agreement among three hematopathologists after independent review of the data from each case. The workstation's diagnosis agreed with the "gold standard" in 515 cases (97.9%). In six of the 11 diagnostic errors, the bone marrow module could not reach a final diagnosis. The five misclassifications would not have resulted in a change of therapy for the patient. The institutional diagnosis of record agreed with the gold standard in 462 cases (87.8%). The results indicate that the workstation is capable of high-quality, reproducible, multiparameter interpretive reporting.
Acute Disease↗
Differential induction of nitric oxide synthase in hepatocytes during endotoxemia and the acute-phase response.
OBJECTIVE: Nitric oxide (NO) is a potent biologic mediator produced by hepatocytes following exposure to cytokines and lipopolysaccharide (LPS). These cytokines are also known to regulate induction of the hepatic acute-phase response. The objective of this study was to determine whether inducible nitric oxide synthase (iNOS), the enzyme that produces NO, is expressed as part of the hepatic acute-phase response. DESIGN: The gene expression for inducible NOS (iNOS) as well as alpha 1-acid glycoprotein (AGP), an established acute-phase reactant, was measured by Northern blot analysis in rat hepatocytes in vivo during endotoxemia (LPS injection) and during the acute-phase response produced by hindlimb turpentine injection. Hepatocyte iNOS messenger RNA (mRNA) levels were correlated with iNOS activity and circulating plasma nitrite and nitrate levels. In vitro, iNOS and AGP mRNA levels were determined in cultured hepatocytes stimulated with interleukin 6 (IL-6), interleukin 1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), or dexamethasone. RESULTS: The AGP mRNA levels were increased in vivo following both LPS and turpentine injection, while iNOS expression was induced only by LPS injection. Hepatocyte iNOS activity and plasma nitrite and nitrate levels also increased after LPS treatment. In vitro, the cytokine combination IL-6, IL-1 beta, and TNF-alpha induced hepatocyte iNOS expression but had minimal effects on AGP in the absence of dexamethasone. Addition of dexamethasone alone markedly increased AGP mRNA levels, with further increases seen with TNF-alpha or IL-1 beta addition. In contrast, dexamethasone decreased iNOS expression. CONCLUSION: The results show that hepatocyte iNOS expression is not part of the acute-phase response induced by remote inflammation and indicates that iNOS is differentially regulated from the acute-phase reactant, AGP.
Acute-Phase Reaction↗
Immediate-early gene expression in EGF-stimulated intestinal epithelial cells.
The mammalian small intestinal epithelium is a continuously renewable population of cells which arise from a proliferative zone of undifferentiated stem cells within the crypts. Epidermal growth factor (EGF) is thought to play a role in the maintenance and proliferative response of the intestinal epithelium. In order to investigate the early changes in intestinal gene expression which occur in response to a mitogenic stimulus, we performed studies in two different cell lines (IEC-6 and HT-29), both of which have characteristics of intestinal crypt cells. Cells were grown in DMEM + 10% FCS at 37 degrees C/5% CO2 and treated with either EGF (10 ng/ml) and/or cycloheximide (CHx) (10 micrograms/ml) for various times. Northern blot analyses were performed on total RNA using 32P-labeled cDNA probes corresponding to various protooncogenes. Our results showed that EGF treatment caused rapid increases in c-fos, c-jun, and junB expression (P < 0.001) in both cell lines. c-fos and c-jun followed similar time courses, peaking at 30 min, whereas junB levels plateaued at 1 hr. The magnitude and time course of protooncogene induction by EGF were similar in the two cell lines. A dose-response experiment indicated peak EGF effects at 10 ng/ml. CHx treatment resulted in greater and more prolonged increases in protooncogene expression when compared to EGF alone, indicating that protein synthesis is not required for protooncogene induction.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Occurrence of Shiga-like toxin-producing Escherichia coli in retail fresh seafood, beef, lamb, pork, and poultry from grocery stores in Seattle, Washington.
Fresh meat, poultry, and seafood purchased from Seattle area grocery stores were investigated for the presence of Shiga-like toxin-producing Escherichia coli by using DNA probes for Shiga-like toxin (SLT) genes I and II. Of the 294 food samples tested, 17% had colonies with sequence homology to SLT I and/or SLT II genes.
Animals↗
Mass casualties on the modern battlefield: a view from the 1st Armored Division (US).
Operations Desert Shield/Desert Storm will go down in history as a resounding success. However, future successes will depend on how much we take away from this experience in the form of lessons learned. This article is a warning message on the need for medical preparedness. The medical personnel shortage remains a problem for both commanders of field units and medical staff. The Professional Filler System, which provides clinicians to deploying combat medical and line units, is not aggressively administered and maintained. Medical Tactical Standard Operating Procedures are not fully integrated, nor are they used in Mission Essential Task List training. LOGOVERWATCH has potential but needs refinement. Finally, important medical and communication equipment needs upgrading to current state-of-the-art standards. On the plus side, the Combat LifeSaver program works well for intensive training on chemical casualties care. Combined with the high state of training and motivation of soldiers and medical professionals, many of the current shortcomings have been masked. This situation cannot go on indefinitely without a degradation of mission capability.
Humans↗
Successful management of postoperative chylothorax with fibrin glue in a premature neonate.
Chylothorax is a potentially serious condition that may complicate a variety of thoracic operations, particularly cardiothoracic procedures for congenital heart disease. Conservative therapy with chest tube drainage of the chyle fluid and dietary manipulations is frequently effective. When conservative treatment fails, surgery may be necessary. In this report, the authors discuss their recent experience with fibrin glue in the management of a 600-g premature neonate who had a postoperative chylothorax. Recent trends in the management of this difficult problem are also discussed.
Chest Tubes↗
Frameshift fidelity during replication of double-stranded DNA in HeLa cell extracts.
The processes by which minus-one frameshifts arise during replication of double-stranded DNA by a human replication apparatus were examined. Using M13mp2 DNA containing the simian virus 40 (SV40) origin of replication and a plus-one frameshift mutation in the lacZ alpha reporter gene, we performed replication reactions using a HeLa cell extract and the SV40 large T antigen. Frameshifts that restore the reading frame to give a blue-plaque phenotype include the loss of one of five consecutive A.T base pairs or any one of 36 non-reiterated base pairs. Although both types of deletions were generated at rates substantially above the background mutant frequency of unreplicated DNA, the rate was highest at the A.T run, suggesting the involvement of a misaligned replication intermediate at this homopolymeric sequence. The error rate for both types of deletions increased as the concentration of dNTPs was increased. A small increase in error rate at the run of A.T base pairs was also observed when a dNMP was added to the replication reaction. These results are consistent with the correction of frameshift intermediates during replication by exonucleolytic proofreading. To examine frameshift error rates on the leading and lagging strands, we compared reversion frequencies for two vectors containing the origin of replication close to, but on opposite sides of, the mutational target. To generate strand-specific errors, nucleotide substrate imbalances were used in replication reactions with these vectors. The results suggest that there is less than a 2-fold difference in the fidelity of leading- and lagging-strand synthesis for deletions at the run of A.T base pairs.(ABSTRACT TRUNCATED AT 250 WORDS)
Adenine↗
An in vitro study of two adhesive systems: third and fourth generations.
The aim of this in vitro study was to compare the adhesive properties of a manufacturer's third and fourth generation dentin adhesive. Vestibular sections of recently extracted third molars were embedded in chemical-cured acrylic resin and ground with 600-grit silicon carbide sandpaper. Fifteen samples were prepared with the adhesive products and the dentin surfaces were analysed by SEM. Twenty-four samples were divided into two groups and prepared with third and fourth generation systems, respectively. Composite filled tubes were then positioned on the prepared dentin surfaces and photopolymerized. The treated samples were kept in distilled water at 37 degrees C for 24 h. Four samples were used to analyze the resin-dentin surface. A tension test was performed on the remaining twenty samples at a crosshead speed of 0.5 mm/min. The results were analyzed using the Fisher and Student t-tests. The fractured surfaces were examined by SEM. The resistance to tensile forces of specimens prepared with the fourth generation system was significantly higher than that obtained after using the third generation system. Thus, as expected from the in vitro tests, the fourth generation system provided better adhesion to dentin than the third generation material.
Adhesiveness↗
Calculation of volume flow rate by the proximal isovelocity surface area method: simplified approach using color Doppler zero baseline shift.
OBJECTIVES: The goal of this study was to develop an accurate, simplified proximal isovelocity surface area (PISA) method for calculating volume flow rate using lower blue-red interface velocity produced by a color Doppler zero baseline shift technique. BACKGROUND: The Doppler color proximal isovelocity surface area method has been shown to be accurate for calculating the volume flow rate (Q) across a narrowed orifice by the formula Q = PISA x Blue-red interface velocity. A hemispheric model is generally used to calculate proximal isovelocity surface area (PISA = 2 pi a2, where a = the radius corresponding to the blue-red interface velocity). Although a hemispheric model is simple, requiring measurement of one radius, it may underestimate the actual volume flow rate because, in the general case, the shape of a proximal isovelocity surface area is hemielliptic. Although a hemielliptic model is generally more accurate for calculating proximal isovelocity surface area, it is more complex, requiring measurement of two orthogonal radii. METHODS: Sixteen in vitro constant flow model studies were performed using planar circular orifices (diameter range 6 to 16 mm). The blue-red interface velocity was changed from 3 to 54 cm/s using color Doppler zero baseline shift. RESULTS: 1) With decreasing blue-red interface velocity, the size of the proximal isovelocity surface area was increased, and its shape changed from hemielliptic to hemispheric. 2) With the blue-red interface velocity in the range 11 to 15 cm/s, the proximal isovelocity surface area became nearly hemispheric; however, it was difficult to determine the blue-red interface radius at a blue-red interface velocity < 10 cm/s because of interface fluctuations. 3) Calculated volume flow rate using the hemispheric proximal isovelocity surface area model with a single radius was relatively accurate at a blue-red interface velocity of 11 to 15 cm/s (mean percent difference from actual volume flow rate was -3.6%). CONCLUSIONS: Because the shape of the proximal isovelocity surface area is nearly hemispheric at a blue-red interface velocity of 11 to 15 cm/s, volume flow rate can be accurately calculated in this proximal isovelocity surface area interface velocity range (produced by zero baseline shift) by measuring a single-interface radius. This approach should be clinically useful for calculating the volume flow rate across stenotic and regurgitant valves and across shunt defects.
Blood Flow Velocity↗
Cytokine induction of interferon regulatory factor-1 in hepatocytes.
BACKGROUND: Interferon regulatory factor-1 (IRF-1) is a transcriptional factor originally cloned from fibroblasts that activates interferons and certain interferon-responsive genes. Because IRF-1 is an "early-immediate" nuclear protein, it can function acutely after trauma or septic stimuli. We have identified IRF-1 expression in hepatocytes in vivo in sepsis. The purpose of this study was to characterize the cytokine signals that up-regulate IRF-1 messenger RNA (mRNA) in cultured hepatocytes. METHODS: Rat hepatocytes were isolated by in situ collagenase perfusion and stimulated in vitro with cytokines. IRF-1 mRNA levels were determined by Northern blot hybridization with a DNA probe for hepatocyte IRF-1 generated with reverse transcription polymerase chain reaction with custom-designed oligonucleotide primers based on the known sequence for T-cell IRF-1. RESULTS: Northern blot of hepatocyte RNA showed a single IRF-1 mRNA band at approximately 2.4 Kb. The mRNA levels were markedly up-regulated (vs control hepatocytes) 2 hours after in vitro stimulation with the cytokines interferon-gamma (17-fold), tumor necrosis factor-alpha (3-fold), and interleukin-1 beta (2-fold). Lipopolysaccharide had no direct effect. CONCLUSIONS: The results showed that IRF-1 is up-regulated in hepatocytes primarily in response to interferon-gamma and to a lesser extent after tumor necrosis factor-alpha or interleukin-1 beta stimulation. This suggests that IRF-1 plays a role in regulating liver gene expression in sepsis; however, the specific genes controlled by IRF-1 remain to be determined.
Animals↗
Adult T-cell leukemia-lymphoma: a clinico-pathologic study of twenty-six patients from Martinique.
Twenty-six cases of adult T-cell leukemia/lymphoma (ATLL) were identified between 1983 and 1991 in Martinique (French West Indies). There were 14 men and 12 women, all of mixed racial descent and born in Martinique. Their ages ranged from 23 to 95 years. The main clinical and laboratory features at initial presentation were peripheral lymphadenopathy (22 cases), hepatomegaly (11 cases), splenomegaly (10 cases), cutaneous lesions (12 cases), hypercalcemia (16 cases), refractory infection by Strongyloides stercoralis (12 cases), and pre-existing autoimmune disorders (4 cases). All patients had absolute lymphocytosis with circulating pleomorphic abnormal lymphocytes. The prognosis was poor, with most patients (20 cases) surviving for less than 6 months. Although the overall clinicopathologic features of ATLL in this series are similar to those described in previous reports, we observed three additional points of interest: a high association with Strongyloides infection, an increased incidence of tropical spastic paresis/HTLV-1 associated myelopathy (TSP/HAM) among the relatives of the patients (5 cases), and the presence of prior collagen vascular diseases.
Adult↗
[Duration of absorption in alcohol intake of 0.3, 0.5 and 0.8 g of alcohol per kg of body weight in 30 minutes].
In expert opinion the time of absorption after ethanol consumption often must be estimated, because back calculation is not permitted during this period of possible ethanol absorption. HEIFER called this time "waiting times" in back calculation. He undertook an investigation of these "waiting times" in drinking experiments with different dosages and a drinking period of 60 minutes. The presented investigation dealt with the maximum "waiting times" after a shorter time of drinking. Within 30 minutes three groups, each amounting to 10 persons, were given 0,8, 0,5 and 0,3 g of ethanol per kg body weight. The results of these experiments showed that the maximum "waiting times" in back calculation after a drinking period of 30 minutes sometimes are longer than the "waiting times", calculated by HEIFER after a drinking period of 60 minutes.
Adult↗
Age, circadian rhythms, and sleep loss in flight crews.
Age-related changes in trip-induced sleep loss, personality (n = 205), and the pre-duty temperature rhythm (n = 91) were analyzed in crews from various flight operations. Eveningness decreased with age (subjects aged 20-30 were more evening-type than subjects over 40). The minimum of the baseline temperature rhythm occurred earlier with age (earlier in subjects aged 30-50 than in subjects aged 20-30). The amplitude of the baseline temperature rhythm declined with age (greater in subjects aged 20-30 than in subjects over 40). Average daily percentage sleep loss during trips increased with age. Among crewmembers flying longhaul flight operations, subjects aged 50-60 averaged 3.5 times more sleep loss per day than subjects aged 20-30. These studies support previous findings that evening types and subjects with later peaking temperature rhythms adapt better to shift work and time zone changes. Age and circadian type may be important considerations for duty schedules and fatigue countermeasures.
Adaptation, Physiological↗
Design and synthesis of novel 6,7-imidazotetrahydroquinoline inhibitors of thymidylate synthase using iterative protein crystal structure analysis.
Antifolate inhibitors of thymidylate synthase (TS) have primarily been based on the structure of folic acid. This paper describes the identification and development of novel 6,7-imidazotetrahydroquinoline TS inhibitors by iterative ligand design, synthesis, and crystallographic analysis of protein-inhibitor complexes. Beginning with a high-resolution crystal structure of E. coli TS (TS, EC 2.1.1.45), an imidazotetrahydroquinoline inhibitor was designed de novo to occupy the folate binding pocket. Structural modifications of the initial compound 1h (Ki approximately 5 microM human/E. coli TS) were then made on the basis of feedback from additional cocrystal structures and activity data. An amino group in the 2-position of the imidazole was found to increase the potency of the series by 1-2 orders of magnitude. Other substitutions on the imidazole ring (1-CH3, 2-CH3, 2-NHCH3, 2-SCH3) generally led to weaker inhibition. Additional improvements in activity were obtained by modification of the substituents on the tetrahydroquinoline nitrogen, bringing the Ki of three of the compounds below 15 nM against the human TS enzyme. The compounds were tested for cytotoxicity and were shown to inhibit the growth of three tumor cell lines in vitro.
Adenocarcinoma↗
Successful treatment of human acute T-cell leukemia in SCID mice using the anti-CD7-deglycosylated ricin A-chain immunotoxin DA7.
The study of new therapeutic approaches for refractory human leukemia has been hampered by the lack of relevant in vivo models with disseminated disease, particularly T acute lymphoblastic leukemia (T-ALL). In the present study we evaluated methods for establishing and therapy of a human T-ALL cell line (MT-ALL) in 73 SCID mice. MT-ALL is a T-cell receptor alpha/beta +, CD3+, and CD7+ leukemia cell line, derived from a patient with refractory disease and early death. Injection of 5 x 10(7) MT-ALL cells i.v. caused disseminated human leukemia in hematopoietic and nonhematopoietic organs in 100% of SCID mice (n = 9) leading to death or terminal disease at 65 to 70 days after a uniform clinical course. To study possible therapeutic approaches for disseminated leukemia we utilized an immunotoxin, DA7, constructed by chemically linking the mouse IgG2b anti-CD7(3A1E) monoclonal antibody which recognizes a pan-T-cell marker expressed on almost all T-cell leukemias to deglycosylated ricin A-chain, a catalytic plant toxin and inhibitor of protein synthesis. Administration of DA7 led to greater than 5 log kill of clonogenic MT-ALL cells in vitro and selectively inhibited protein synthesis. DA7 was administered to mice at a dose of 10 micrograms/mouse/day for 5 consecutive days starting 8 days after i.v. inoculation of leukemia. The immunotoxin therapy resulted in significant long term survival over 348 days compared to untreated or control mice treated with anti-CD7 antibody and deglycosylated ricin A-chain which were all dead by day 70 (P less than 0.001). Even after more than 11 months there was no evidence of disease in 82% of the DA7 treated animals. SCID mice given i.p. injections (n = 9) developed an i.p. tumor mass but demonstrated metastasis outside the peritoneum with disseminated leukemia in hematopoietic and nonhematopoietic organs, a finding different from most conventional nude mouse models. The leukemia was fatal in 100% and killed the animals at 68-95 days. SCID mice given i.p. injections of MT-ALL completely responded to therapy with DA7, resulting in survival of 100% of the animals (n = 10) at 216 days (P less than 0.001 compared to untreated animals). Anti-CD7 antibody, deglycosylated ricin A-chain, and a control anti-melanoma immunotoxin (IND1-RTA) showed no therapeutic effect. We conclude that DA7 is an effective in vivo therapeutic agent against human MT-ALL in the SCID mouse system, suggesting potential usefulness for therapy of humans with poor prognosis T-cell leukemia.
Animals↗
Triple-helix formation is compatible with an adjacent DNA-protein complex.
The effect of oligonucleotide-directed triple-helix formation on the binding of a protein to an immediately adjacent sequence has been examined. A double-stranded oligonucleotide was designed with a target site for the binding of a pyrimidine oligonucleotide located immediately adjacent to the recognition sequence for the herpes simplex virus type 1 (HSV-1) origin of replication binding protein, which is encoded by the UL9 gene of HSV-1. Since the optimal conditions for the binding of the UL9 protein and the pyrimidine oligonucleotide to the duplex DNA are markedly different, a pyrimidine oligonucleotide was designed to optimize binding affinity and specificity for the target duplex oligonucleotide. Consideration was given to length and sequence composition in an effort to maximize triple-strand formation under conditions amenable to the formation of the UL9-DNA complex. Using gel mobility shift assays, a trimolecular complex composed of duplex DNA bound to both a third oligonucleotide strand and the UL9 protein was detected, indicating that the UL9-DNA complex is compatible with the presence of a triple helix in the immediately adjacent sequences.
Animals↗
Molecular cloning and sequencing of the Mexico isolate of hepatitis E virus (HEV).
Hepatitis E virus (HEV) is the major causative agent of hepatitis E or what was formerly known as enterically transmitted non-A, non-B hepatitis. The disease has a worldwide distribution but occurs principally in developing countries in any of three forms: large epidemics, smaller outbreaks, or sporadic infections. Genetic variation of different HEV strains was previously noted and it will be important to determine the extent to which this variation may pose problems in the diagnosis and treatment of HEV infection. To analyze differences at the genetic level between HEV(Mexico; M) and the previously characterized HEV(Burma; B) and HEV(Pakistan; P) isolates, overlapping cDNAs were cloned from samples obtained from an infected human and an experimentally inoculated cynomolgus macaque. These cDNA clones, representing the nearly complete (7185-bp) genome of HEV(M), confirmed an expression strategy for the virus that involves the use of 3 forward open reading frames (ORFs). The HEV(M) strain has an overall 76 and 77% nucleic acid identity with the HEV(B) strain and HEV(P) strain, respectively; however, the degree of sequence variation was not uniform throughout the viral genome. A hypervariable region was identified in ORF1 that exhibited a 58 and 54% nucleic acid sequence and 13% amino acid similarity with the Burma strain and the Pakistan strain, respectively. A large number of the nucleotide differences occurred at the third codon position, with the deduced amino acid sequences similarity of 83, 93, and 87% between HEV(M) and HEV(B) isolates in ORF1, ORF2, and ORF3, respectively, and with 84, 93, and 87% amino acid identities between HEV(M) and HEV(P) isolates in ORF1, ORF2, and ORF3, respectively. The nucleotide sequences derived from the highly conserved regions of HEV genome will be useful in developing polymerase chain reaction-based tests to confirm the viral infection. Knowledge of the extent of the sequence variation encountered with HEV will not only aid in the future development of diagnostic and vaccine reagents but also further our understanding of how HEV strain variation might impact the pathological outcome of infection.
Amino Acid Sequence↗