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Biomedical subjects

D Nguyen

Publications and source records attributed to D Nguyen.

At least 127 records · Page 7Linked to original sources
PubMed1992

Myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML) with myelofibrosis.

Acute myeloid leukemias (AML) and myelodysplastic syndromes (MDS) enter rarely in the differential diagnosis of myelofibrosis (MF). MF of marked intensity, resulting in either "dry taps" or non-representative smears, is encountered in approximately 10% of cases. MF may be observed in any type of AML, most frequently in acute megakaryoblastic leukemia (M7). Apart from some typical cases of MDS, MF is associated with cases of acute myelodysplasia with myelofibrosis (and a major megakaryocytic component). This syndrome has been described under various headings: acute or malignant myelosclerosis, and acute MF. It should be distinguished from M7 and from myeloproliferative syndromes.

Acute Disease↗
PubMed1992

Ventilatory effects of dexmedetomidine, atipamezole, and isoflurane in dogs.

Dexmedetomidine (DMED) is a novel alpha 2 adrenergic agonist that has been shown to have potent analgesic and anesthetic sparing effects. This study was designed to investigate the effects of DMED, both alone and combined with isoflurane, on resting ventilation, the hypercapnic response, and the hypoxic response in dogs. When given alone, 1 microgram/kg decreased resting ventilation by 22% but at larger doses (10, 20, and 100 micrograms/kg) resting ventilation increased, doubling at 100 micrograms/kg. Doses of 10 micrograms/kg and greater caused a maximum depression of 60% in the slope of the hypercapnic response, but no dose had a significant effect on the hypoxic ventilatory response. A dose of 3 micrograms/kg of DMED reduced isoflurane MAC from 1.3% to 0.37%, and the ventilatory effects of this 1 MAC combination were intermediate between the awake values and those of isoflurane-anesthetized (1.3%) dogs. Atipamezole is a specific centrally acting alpha 2 receptor antagonist and when given with DMED in isoflurane-anesthetized dogs prevented the ventilatory depression. However, atipamezole alone also ventilatory stimulating effects, which may indicate tonic alpha 2 adrenergic activity. The ventilatory depression caused by DMED, either alone or combined with isoflurane, at doses that significantly reduce anesthetic requirements are relatively mild.

Adrenergic alpha-Agonists↗
PubMed1992

Regurgitant volume estimation in patients with mitral regurgitation: initial studies using color Doppler "proximal isovelocity surface area" method.

Doppler color flow mapping of a proximal isovelocity surface area (PISA), calculated from a blue-red aliasing radius, has been shown in vitro to be accurate for estimating volume flow rate across a narrowed orifice. Volume flow rate (in cm 3/sec) can be calculated as PISA (in cm 2) x aliasing velocity (in cm/sec). This method has advantages over other color Doppler approaches in that PISA-derived volume flow rate calculations appear to be independent of machine parameter settings and orifice shape. We evaluated the clinical applicability of the PISA method in 49 patients with native valve mitral regurgitation (MR). Color Doppler flow mapping was performed at color aliasing velocities of 54-72 cm/sec. Twenty-four patients were excluded because a color aliasing radius was not clearly seen: 20 of these 24 patients had mild MR. In the remaining 25 patients, the ratio of maximum regurgitant jet area-to-left atrial area, as well as the regurgitant stroke volume estimated using the time-velocity integral method, were compared to regurgitant stroke volume calculated from the PISA method. Maximum PISA was calculated using a formula derived from previous in vitro studies: PISA = 8.05 x r 2, where r is the maximum color Doppler aliasing radius in the apical four-chamber view.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1991

Phenotypic expression of bronchoalveolar lavage cells in lung rejection and infection.

The differentiation of episodes of lung allograft rejection from infection continues to be a problem. Bronchoalveolar lavage (BAL) has recently gained some success in the diagnosis and management of interstitial lung disease. To assess the usefulness of BAL in differentiating between lung allograft rejection and infection, we examined the differences in cellular subsets of BAL and peripheral blood (PBL) samples in a controlled canine model of rejection or pneumonia. Single-lung allotransplants were allowed to undergo rejection by withdrawing immunosuppressive agents (n = 6). In another group of dogs (n = 5), pneumonia was induced by transbronchial injection of Pseudomonas aeruginosa and melted agar followed by bronchial fulguration. Cells obtained from bronchoscopic BAL and PBL samples were labeled with functionally characterized cross-reactive murine monoclonal antibodies. Transthoracic needle biopsies and transbronchial biopsies were done to assess their adequacy in examining the rejecting or infected lungs and were compared with open lung biopsies. We found the following: (1) the percentage of DT2-labeled cells was significantly higher (p less than 0.05) in BAL samples from rejecting lungs compared with infected lungs; (2) the PBL/BAL ratio of DT2-labeled cell percentages was significantly higher in pneumonia (1.7 +/- 0.3) than rejection (0.5 +/- 0.2) (p less than 0.004); (3) the percentage of E11-labeled cells in PBL samples was significantly higher (p less than 0.02) in rejection than in infection; and (4) the ratio of WIG4 to DT2 cellular subset percentages in BAL samples from rejection (26.8 +/- 9.9) was significantly lower than from infection (61.0 +/- 22.9) (p less than 0.03). Transthoracic and transbronchial biopsies did not always yield representative specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Bronchoalveolar lavage in lung transplantation.

One of the dilemmas in the management of lung allotransplant recipients is our inability to precisely determine the cause of graft dysfunction. Differentiating between lung allograft infection, rejection, atelectasis, or ischemic injury remains a difficult task. Tests directed at identifying systemic abnormalities such as peripheral blood analysis so far have been nonspecific and unlikely to accurately and promptly represent changes occurring within the lungs. Transbronchial biopsy and bronchoalveolar lavage have emerged as two methods with the most potential for aiding in the establishment of diagnosis. This review attempts to provide the readers with a current knowledge of the cellular events in lung allograft and the status of bronchoalveolar lavage in experimental and clinical lung transplantation.

Bronchoalveolar Lavage Fluid↗
PubMed1991

Reusable gels for germanium-68 sources.

Two water-soluble gels, gelatin and Carbowax, were mixed with radioactive 68Ge solutions and evaluated for their use as long-lived (half-life, 280 days) radioactive sources. These gels melt at 40-50 degrees C and solidify at room temperature. The amount of 68Ge mixed with them can be increased or decreased as needed, eliminating waste of 68Ge. These gel sources also may replace short-lived 68Ga (half-life 68 min) as attenuation correction sources in positron emission tomography (PET) and reduce frequency of source preparation, thus reducing exposure of PET operators to radiation.

Gelatin↗
PubMed1991

Successful treatment of steroid-resistant double-lung allograft rejection with Orthoclone OKT3.

An 18-yr-old woman with cystic fibrosis who received a double-lung transplant developed a severe episode of acute lung rejection. Bronchoalveolar lavage and transbronchial biopsy were used to establish the diagnosis. The rejection was refractory to administration of high-dose pulse steroids. OKT3 therapy was successfully used to reverse this episode. This is the first case report of a steroid-resistant double-lung allograft rejection successfully treated with OKT3.

Adolescent↗
PubMed1991

[Characteristics of human growth hormone produced by genetically engineered mammalian cells].

Saizen is human growth hormone produced by mammalian cells by genetic engineering. It is identical with hypophyseal GH as regards various physical and chemical parameters. A number of tests did not reveal an alien protein at the 1 ppm level, nor the presence of viruses, and the DNA level is below the detection range. According to these results Saizen is a highly purified growth hormone.

Growth Hormone↗
PubMed1991

Warm ischemia induces alteration in lung immune cell functions.

Warm ischemia is an important factor in early allograft dysfunction. To elucidate cellular events involved in such lung injury, we examined the effects of warm ischemia on the cytotoxic function of lymphocytes retrieved by bronchoalveolar lavage as compared with peripheral blood lymphocytes. Warm ischemia of the lung was induced in eight dogs by crossclamping left hilar structures for 1 hour. Bronchoalveolar cells from ischemia left and unaffected right lungs, as well as blood lymphocytes, were isolated before operation and 2 hours, 72 hours, and 7 days after operation. Lung and blood lymphocytes were assayed for natural killer and lectin-dependent cell-mediated cytotoxicity. Warm ischemia resulted in a significant impairment of natural killer activity within 2 hours of reperfusion (49% of preoperative control cytolysis, p less than 0.01). There was a significant increase in natural killer activity in bronchoalveolar lavage mononuclear cells 72 hours after reperfusion injury (178.4% of preoperative value, p less than 0.01). Interestingly, these functional alterations were not paralleled with changes seen in the peripheral blood lymphocytes or the opposite nonaffected lungs, where the natural killer activity appeared significantly depressed at 72 hours. Similarly, lectin-dependent cell-mediated cytotoxicity was noted to be increased in the bronchoalveolar lavage from the ischemic lung (179.5%, p less than 0.01) but decreased in the bronchoalveolar lavage from the nonaffected lung and peripheral blood lymphocytes at 72 hours after injury. We conclude that warm ischemia is associated with a functional alteration of the local lung immune cells. Such alteration is not observed in cells from the opposite lung or peripheral blood. The observed increase in nonspecific cytotoxicity of bronchoalveolar lymphocytes can be causative in the early damage seen in poorly preserved lung allografts.

Animals↗
PubMed1990

New stoma stent applicable in long-term tracheostomy.

As long-term tracheostomy becomes a more common procedure, the need has arisen for a means of maintaining stoma patency. This article presents a new self-retained physiologic prosthesis intended for use as a stoma stent in long-term tracheostomy. It may also be applied in a wide range of short-term conditions. The concepts and techniques of long-term tracheostomy are highlighted. Experience in applying this stent in 75 patients with a followup of more than 28 months is presented.

Adolescent↗
PubMed1990

[Abdominal echography in colonic diseases].

In the past few years, several studies have assessed the visualization of digestive diseases by ultrasound, but its clinical accuracy has been rarely defined. Thus we evaluated the contribution of sonographic examination as an initial diagnostic mean in the detection of colonic lesion. During a period of thirty six months (June 85-June 88) when we performed a standard sonographic abdominal examination, we utilized ultrasound to look for thickening or other modifications of the large bowel wall, if the clinical findings suggested a colonic disease. In these conditions we performed 453 US examinations. In our study, 363 cases were considered to be negative and the controls demonstrated colonic wall lesions in 24 cases. Thus the sensitivity was one of 77%. The sonographic examination was positive in 90 cases with 6 false positives. Thus our specificity reached 98.2% and the accuracy achieved was 93.3%. Thus sonographic examination appears to be a rapid, non invasive, mobile, mean of examining the abdominal cavity and also the large bowel in all patients. If this examination is negative, a colonic disease is possible since sensitivity is 77%. On the other hand, if the examination is positive, a colonic disease is very probable, since specificity reached 98.2%. The accuracy of US Colonic examination is 93.3% and with using abdominal plain film, theses percentages may be improved.

Adult↗
PubMed1989

Biological monitoring of fire fighters: sister chromatid exchange and polycyclic aromatic hydrocarbon-DNA adducts in peripheral blood cells.

Fire fighters are exposed to potentially carcinogenic combustion and pyrolysis products during the course of their work. The present study was designed to test 43 fire fighters and matched controls for DNA damage which might be related to occupational carcinogen exposures. Using peripheral blood lymphocytes, we examined (a) baseline sister chromatid exchange (SCE) frequency and (b) SCE induction by in vitro mutagenic challenge with mitomycin C. Using nucleated peripheral blood cells, we examined (c) polycyclic aromatic hydrocarbon-DNA adduct levels by assessing benzo(a)pyrene diol epoxide (BPDE)-DNA antigenicity. Exposures were determined from histories of fire-fighting activity. The presence of confounding factors (e.g., tobacco smoking, charcoal-broiled food consumption, etc.) was determined by questionnaire. Plasma cotinine levels were measured to assess recent exposures to tobacco smoke. White fire fighters exhibited a significantly higher risk for the presence of detectable BPDE-DNA antigenicity than white controls (odds ratio, 3.4; 95% confidence interval, 1.08-10.5 after adjustment). Consumption of charcoal-broiled food less than 3 times a month was associated with a smaller proportion of individuals exhibiting measurable (positive) BPDE-DNA antigenicity, while consumption of broiled food greater than 3 times a month did not affect the proportion of positive individuals. Daily alcohol consumption was associated with a larger proportion of individuals exhibiting positive BPDE-DNA antigenicity, (P = 0.07). Tobacco smoking and charcoal-broiled food consumption, but not fire fighting, were associated with increased levels of baseline SCE. Sensitivity to SCE induced by mitomycin C in cultured peripheral lymphocytes was similar in fire fighter and control groups. However, sensitivity of individual fire fighters to mitomycin C-induced SCE was correlated with number of fires fought in the previous 24 h.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1989

Primary meningeal small lymphocytic lymphoma.

We report an unusual case of primary meningeal small lymphocytic lymphoma presenting as a solitary large extraaxial mass lesion. Histology revealed a prominent pseudofollicular pattern. There was no evidence of extracranial lymphoma by noninvasive staging procedures. Bone marrow and peripheral blood were also negative.

Aged↗
PubMed1989

Acute myeloid leukemia, FAB M-1 microgranular variant: a multiparameter study.

Acute leukemia was diagnosed in 62 adults and children over a recent 13-month period. Using light microscopy, cytochemical profiles, surface markers, and cytogenetics, 25 cases were classified as acute myeloid leukemia (AML) and 32 as acute lymphoblastic leukemia (ALL). The remaining 5 cases of de novo acute leukemia were unclassifiable. The routine cytochemical battery used on these 62 cases included: myeloperoxidase, sudan black B, nonspecific esterase, and periodic acid-Schiff (PAS). Flow markers utilized were: T3, T4, T5, T8, T10, T11, B1, B4, kappa, lambda, Ia, CALLA, Mo1, Mo2, My4, My7, My8, and My9. TdT was performed by immunoperoxidase and ELISA methods. The five unclassified cases were cytochemically negative and expressed no B- or T-cell-specific antigens, or TdT positivity. The morphologic differential diagnosis was between FAB L-2 and M-1. Karyotypic abnormalities involving chromosomes 3 and 7 were suggestive of myeloid origin in 2 of 4 patients studied. Flow cytometry demonstrated My7 on greater than 50% of blasts from two cases. Myeloperoxidase ultracytochemistry showed reaction product in small primary granules of blasts from all 5 cases. Positive cells contained only 1-2 granules/cell profile. The number of positive cells per case was in the range 10-20%. We conclude from this study that ultracytochemistry is very useful in providing definitive diagnosis and accurate subclassification of some AML FAB M-1 cases, particularly when light microscopic cytochemistry, cytogenetics, and flow cytometric markers are noncontributory. We propose to designate these acute "unclassified" leukemias as AML FAB M-1 "microgranular" type.

Acute Disease↗
PubMed1989

In vivo dynamics of murine tumor necrosis factor-alpha gene expression. Kinetics of dexamethasone-induced suppression.

Tumor necrosis factor-alpha (TNF) has been implicated as an important, proximal mediator of many of the pathophysiologic effects observed during septic shock. In vitro studies have demonstrated that the glucocorticoid dexamethasone (Dex) will suppress the production of TNF; yet, clinical studies have shown that glucocorticoids are not protective in septic shock. In this paper we described the in vivo effects of lipopolysaccharide (LPS) on the kinetics of local and systemic TNF production, the time dependent expression of TNF mRNA, and the suppression of both TNF mRNA and bioactive protein using a defined treatment protocol of Dex. Peritoneal macrophages were elicited by CBA/J mice in the injection of complete Freunds adjuvant and the mice challenged with an intraperitoneal injection of LPS 2 weeks later. Kinetic studies showed that the peak of TNF production occurred 1 hour post LPS injection and reached a maximum of 775 units/ml within the ascites and 26 units/ml within the plasma. Northern blot analysis of mRNA extracted from peritoneal cells showed a peak of mRNA 30 minutes post LPS challenge. Dose-response studies disclosed that 10 micrograms of LPS/mouse produced maximal TNF within the ascites fluid, and half-maximal stimulation occurred at 70 ng LPS/mouse. Mice treated with Dex in vivo before LPS challenge showed a dramatic reduction in TNF production within both the ascites and plasma, and Northern blot analysis showed a corresponding reduction in the TNF specific mRNA. Further studies revealed that mice treated with 4 mg/kg of Dex intraperitoneally 4 hours before, or at the time of LPS challenge, had dramatic reductions in TNF levels within both the ascites and plasma. However, delaying the treatment only 20 minutes after LPS injection failed to significantly reduce TNF in either compartment. These data may provide a rationale why glucocorticoids are not clinically efficacious in the treatment of septic shock, since there is rapid upregulation of LPS-induced TNF gene expression. By the time patients develop clinical signs and symptoms of septic shock there are already preformed, circulating levels of TNF.

Animals↗
PubMed1989

Differential diagnosis between T-cell lymphoma and Hodgkin's disease: the value of mitotic counts and pericapsular infiltration.

The distinction between peripheral T-cell lymphoma (PTCL) and Hodgkin's disease (HD), particularly HD of the mixed cellularity subtype (HDMC), can be difficult at times using current morphologic criteria. This study assessed the value of using mitotic activity and pericapsular invasion in discriminating between the two diseases. Mitotic activity was evaluated in 64 cases of HDNS (nodular sclerosis), 51 of HDMC, 14 of HDLP (lymphocyte predominant), 7 of HDLD (lymphocyte depleted), and 28 cases of PTCL. The number of mitoses in random high-power fields (hpf) was counted independently by two observers. Interobserver agreement on mitotic counts was achieved with a 0.97 coefficient of correlation. Statistical analyses demonstrated significant differences in mitotic counts between HD and PTCL (p less than 0.01), but not within the subtypes of HD. A value of greater than 20 mitoses/20 hpf was obtained in only 10% of HD, in contrast to 70% of PTCL. The mitotic rate was greater than 40/20 hpf in 43% of PTCL, but in no case of HD. In addition, perinodal extension of disease was a significant differentiating feature between PTCL and HD, especially HDMC (p less than 0.001). There was also a significant difference in the age distribution between patients in the two disease groups, with PTCL being seen more frequently in the older age group. The results of this study confirm that counting of mitoses is reproducible, and that mitotic activity and the presence of pericapsular disease are two additional morphologic criteria that are helpful in making the distinction between HD and PTCL.

Adolescent↗