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Biomedical subjects

R Tran

Publications and source records attributed to R Tran.

At least 19 recordsLinked to original sources
PubMed2004

Infectious enteritis after intestinal transplantation: incidence, timing, and outcome.

AIM: To review the incidence, timing, and outcome of infectious enteritis after intestinal transplantation (IT). METHOD: A retrospective review of all patients undergoing IT at a single institution between 1991 and 2003 was analyze with standard statistical tools. RESULTS: Among 33 IT recipients, 13 (39%) developed 20 culture- or biopsy-proven episodes of infectious enteritis. The recipient demographics were 77% men and median age 2.6 years. Infections were diagnosed at a median of 76 days (32 to 1800) after IT. There were 14 viral (CMV one, rotavirus eight, adenovirus four, EBV one, three bacterial (Clostridium difficile), and three other infections (Giardia lamblia one, cryptosporidium two). Complete resolution was achieved in 17 (94%) infectious after appropriate antimicrobial or conservative therapy. Interestingly, there were six rejection episodes following infectious enteritis. Grafts were lost to rejection after rotaviral enteritis (n = 1) and adenoviral enteritis misdiagnosed as rejection (n = 1). Patient and graft survival were not adversely affected by infections. CONCLUSIONS: Infectious enteritis occurs frequently after IT. Viral agents are the cause in two-thirds of cases. With supportive care and appropriate treatment, resolution is possible in the majority of cases. Differentiating rejection and infection by histopathology can be difficult.

Adult↗
PubMed2000

Decreased production of local immunoglobulin A to Pneumocystis carinii in bronchoalveolar lavage fluid from human immunodeficiency virus-positive patients.

An enzyme-linked immunosorbent assay and a Western blot analysis were developed to study the antibody response to Pneumocystis carinii in serum and bronchoalveolar lavage fluid from 27 human immunodeficiency virus 27 (HIV)-infected patients with P. carinii pneumonia (Pcp), 32 patients without Pcp, and 51 HIV-negative controls. Urea was used for the correct dilution of epithelial lining fluid, and albumin was used to evaluate transudation from plasma for the assessment of local production of antibodies to P. carinii. By contrast with those of immunoglobulin G (IgG), IgA responses to P. carinii were increased in serum from HIV-positive patients compared to negative controls. Local production of antibodies to P. carinii, especially IgA, was decreased in patients with Pcp. In a study of 10 patients of each group, IgG and IgA responses to gp116 from P. carinii were lower in patients with Pcp than in other groups. These results suggest that, in addition to alveolar macrophages, local antibodies may play a role in host defense against P. carinii.

Animals↗
PubMed1997

Humoral immune response within the lung in HIV-1 infection.

In order to study the humoral immune defences in the respiratory tract during HIV-1 infection, we measured the levels, local productions and anti-HIV and antibacterial activities of IgG and IgA in the bronchoalveolar lavage fluid (BALF) and serum of 61 adult patients with severe HIV infection and of 56 HIV- controls. Albumin was used as the serum transudation factor. The increase of immunoglobulin levels in the serum of HIV-infected patients was confirmed. The IgG level was also increased in epithelial lining fluid (ELF), whereas the total IgA level was unchanged and secretory IgA (SIgA) level was decreased. The ELF/serum immunoglobulin ratios suggested that the IgG present in ELF resulted mainly from transudation, in contrast to SIgA, which was synthesized locally in controls but greatly diminished in HIV-infected patients. IgG to HIV-1 could be detected in BALF of all the patients, but IgA to HIV-1 only in 30% of patients. BAL IgG reacted more consistently and with a broader array of HIV-1 antigens than did IgA. BAL IgA, when present in samples, reacted primarily with viral envelope antigens. Because IgA specificities to some HIV-1 antigens were detected more intensively by BAL than by serum immunoglobulins, we conclude that the mucosal immune response is distinct from that in serum. IgG antibody activity to Streptococcus pneumoniae was decreased in HIV-infected patients' sera, and IgA antibody activities to S. pneumoniae and to Pseudomonas aeruginosa were decreased in ELF in HIV-infected patients.

Acquired Immunodeficiency Syndrome↗
PubMed1994

[MRI of the thorax: current applications and perspectives].

Magnetic resonance imaging is an accurate technique in chest investigation, but is used less frequently than computed tomography. The sequences currently available allow visualisation of the mediastinum and chest wall. The most important clinical applications concern staging of tumours of the lung apex, evaluation of mediastinal tumours occupying the posterior mediastinum and laterocardiac region, noninvasive investigation of acquired and congenital lesions of the aorta. The applications of MRI will probably be modified if investigation of the lung is made possible by the use of new sequences.

Adenocarcinoma↗
PubMed1992

[How can intrathoracic lymphatic involvement be assessed: does tomography have a role? What is the contribution of computed tomography and MRI?].

The authors report their analysis of the literature on the evaluation of intrathoracic extension of non-small-cell bronchial cancers to lymph nodes, using tomography, computed tomography and magnetic resonance imaging. The criteria used to assess the metastatic character of a lymph node, the characteristics of the populations studied and the methods of comparison with the clinicopathological "truth" account for the variations of the results published. Tomographs are useless today. The performances of CT and MRI are equivalent, and it is not necessary to associate both techniques. Although its performances are mediocre, CT allows mapping the mediastinal lymph nodes, which is useful to continue the assessment of extension and to make decisions.

Carcinoma, Non-Small-Cell Lung↗
PubMed1990

Biocompatibility of hemoglobin solutions. II. The inflammatory reaction of human monocytes and mouse peritoneal macrophages.

This study explored the inflammatory mechanism of toxicity of hemoglobin solutions (Hb-S). Human monocytes and mouse activated peritoneal macrophages were incubated with seven different solutions. The first four consisted of non-cross-linked bovine Hb. Of these, Hb-SI was incompletely purified of stromal phospholipids, Hb-SII was contaminated with environmental bacterial endotoxins, Hb-SIII was pure hemoglobin, and Hb-SIV was pure Hb with the addition of superoxide dismutase (SOD), catalase (CAT), and mannitol (M). The other three solutions were made of pure bovine Hb cross-linked with different agents: Hb-SV, reacted with glutaraldehyde; Hb-SVI reacted with bis-3,5-dibromosalicyl fumarate (DBSF); and Hb-SVII reacted with a ring-opened dialdehyde derivative of 5'(pyro)-phosphate of adenosine (ATP) (o-ATP). The reaction of monocytes and macrophages was studied in terms of (a) O2-derived radicals, as determined by the measurement of H2O2 and lipid peroxides; (b) complement factor C3a desArg; (c) 6-keto-prostaglandin F1 alpha (stable metabolite of prostacyclin); and (d) TxB2 (stable metabolite of thromboxane) released into the culture supernatants. The most significant reactions were obtained with the solutions contaminated with stromal phospholipids or bacterial endotoxins. Pure Hb was less reactive. Further reduction in proinflammatory activity was achieved by the addition of oxygen radical-scavengers (SOD, CAT, and M), or by the cross-linking of Hb with DBSF or o-ATP.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

Nephrotoxicity of hemoglobin solutions.

Nephrotoxicity is a problem of hemoglobin solutions (HbS) that still awaits full elucidation and correction. Therefore, a study was conducted using five HbS with different characteristics to replace 1/3 of blood volume in five groups of rabbits. All HbS contained bovine Hb, 6.5 g/dl, dissolved into a balanced electrolyte solution. HbS-I was Hb incompletely purified of stromal phospholipids and environmental bacterial endotoxins, and uncrosslinked; HbS-II was pure Hb non crosslinked; HbS-III was completely purified and crosslinked; HbS-IV was like HbS-III, but with pH 8.4; and HbS-V was like HbS-III, with the addition of mannitol. The effects of blood replacement with these solutions were studied on: (a) PAH clearance (expression of renal plasma flow); (b) endogenous creatinine clearance (expression of glomerular filtration); (c) fractional excretion of sodium and (d) urine/plasma osmolarity (expressions of tubular function). Histological changes were assessed after 24 hours. Significant alterations were observed in decrescent order following the administration of HbS-I, -II and -III, while HbS-IV and -V were well tolerated. These results suggest that the nephrotoxicity of Hb solutions can be prevented by the following steps: (1) complete purification of Hb; (2) complete crosslinking; and (3) protection of the kidney by alkalinization of the urine and/or the addition of mannitol.

Animals↗
PubMed1989

Modulation of carcinoembryonic antigen messenger RNA levels in human colon carcinoma cells by recombinant human gamma-interferon.

Recombinant human interferons have recently been shown to enhance tumor antigen expression, including carcinoembryonic antigen (CEA), on the surface of human carcinoma cells, which results in an increase in the targeting of antitumor monoclonal antibodies (MAb) in vivo. We report here the effect of recombinant human gamma-interferon (HuIFN-gamma) on the expression of human CEA and its related transcripts in several human colon carcinoma and normal human fibroblast cell lines. The colon tumor cell lines HT-29, WiDr, and LS-174T were each shown to express different constitutive levels of CEA glycopeptide, as measured by the binding of the CEA-specific MAb COL-4. Treatment with HuIFN-gamma enhanced the level of binding of COL-4 in total cell extracts of HT-29 and WiDr cells 2.5- and 6.5-fold, respectively. Using a CEA complementary DNA probe, this increase in MAb binding was shown to be accompanied by a 6- to 11-fold increase in the steady state levels of three CEA transcripts with sizes of 4.2, 3.5, and 2.8 kilobases. On the other hand, HuIFN-gamma treatment had no effect on the level of COL-4 binding or expression of CEA transcripts in LS-174T colon carcinoma cells, which are high constitutive expressors of CEA glycoprotein. Normal human fibroblast cell lines MRC-5 and WI38 had no detectable cytoplasmic CEA glycopeptide levels nor did they contain detectable levels of CEA mRNA, either before or after treatment with HuIFN-gamma. In contrast, HuIFN-gamma induced the de novo expression of the normal major histocompatibility complex class II antigen, HLA-DR, on HT-29 and WiDr colon cancer cells as well as the two fibroblast cell lines. Treatment of the LS-174T cell line with HuIFN-gamma did not result in the induction of class II HLA-DR antigen. These observations suggest that some common factors may be involved in the regulation of the CEA and class II histocompatibility genes. In addition, the demonstration that HuIFN-gamma enhances CEA expression in some carcinoma cell lines but fails to induce de novo expression of CEA transcripts in fibroblasts supports the potential application of HuIFN-gamma in enhancement of tumor targeting of antitumor MAbs and adds to our understanding of the mechanism of gamma-interferon-mediated up-regulation of some tumor antigens.

Carcinoembryonic Antigen↗
PubMed1989

Toxic factors in the red blood cell membrane.

The toxic effects of hemolysed RBCs have been studied for more than 100 years, but the specific factors involved have not been identified. This study focused on phosphatidylethanolamine (PE) and phosphatidylserine (PS), two aminophospholipids that normally reside on the cytoplasmic side of the red cell membrane. An in vitro experiment with murine peritoneal exudate macrophages showed that PE and PS: a) stimulated the production of H2O2, complement factor C3a, prostacyclin, and thromboxane at a dose of 5 micrograms/ml; b) produced cell injury, evidenced by release of lipid peroxides, LDH, and by morphologic changes on phase-contrast and electron microscopy at a dose of 50 micrograms/ml; and c) caused cell death in 50-66% of cells at a dose of 100 micrograms/ml. An in vivo experiment showed that PE and PS injected intravenously into various groups of rabbits: a) caused only transient hypotension at a dose of 0.05 mg/kg body weight; b) caused significant hypotension, cardiac arrhythmias, bronchospasm, activation of intravascular coagulation, complement, platelets, and leukocytes with release of histamine, serotonin, and thromboxane at a dose of 0.10 mg/kg; and c) caused cardiac arrest and death at a dose of 0.30 mg/kg. In contrast, the phospholipids of the outer cell membrane (phosphatidylcholine and phosphatidylinositol) caused minimal toxicity in vitro and none in vivo.

Animals↗
PubMed1989

Biocompatibility of hemoglobin solutions. I. Reactions of vascular endothelial cells to pure and impure hemoglobins.

Hemoglobin (Hb) solutions can cause vasoconstriction and activation of intravascular coagulation. Because the endothelium plays a major role in the regulation of vascular tone and hemostasis, a study was conducted of human umbilical vein endothelial cells (EC) incubated with various Hbs. Cell injury was evaluated by electron microscopy and the release of lactic dehydrogenase, H2O2, and procoagulant "tissue factor." Cell reaction was assessed by the measurement of 6-keto-prostaglandin F (PGF)1 alpha (metabolite of prostacyclin) and thromboxane B2 (metabolite of thromboxane A2). Incubation with unmodified bovine hemoglobin for 24 h caused no cell injury and a reaction characterized by 48.4 +/- 8.2% increase in 6-keto-PGF1 alpha production, accompanied by 40.2 +/- 9.4% reduction in thromboxane (Tx)B2 (compared with a control group of EC incubated with saline solution). Incubation with a nonpure Hb solution (Hb plus red blood cell membrane aminophospholipids; a-PLs) caused cell injury with significant release of tissue factor, plus a reaction characterized by 97.5 +/- 12.5% increase in TxB2 production accompanied by 25.3 +/- 3% reduction in 6-keto-PGF1 alpha. A second nonpure Hb [Hb plus bacterial environmental endotoxin (E)] caused cell injury, the release of tissue factor, and increased production of both prostaglandins, with greater release of TxB2 (197 +/- 17%) than of 6-keto-PGF1 alpha (112 +/- 8.3%). These data indicate that the endothelium reacts differently to pure and nonpure hemoglobins. The biocompatibility of Hb solutions, with regard to vasoconstriction and activation of intravascular coagulation, depends on the absence of stromal a-PLs and bacterial E.

Animals↗
PubMed1989

Fatal hepatic necrosis caused by disseminated type 5 adenovirus infection in a renal transplant recipient.

This is an unusual case of fatal hepatic necrosis caused by disseminated type 5 adenovirus in a renal transplant recipient. This adult patient may have been colonized at the time of transplantation with a kidney from a pediatric donor. The adenovirus became invasive when the host's cellular immune system was suppressed by high doses of corticosteroids given to reverse acute allograft rejection.

Adenoviridae Infections↗
PubMed1988

Correlation of DNA hypomethylation with expression of carcinoembryonic antigen in human colon carcinoma cells.

Using an assay based on the binding of a carcinoembryonic antigen (CEA)-specific monoclonal antibody, we have examined the expression of carcinoembryonic antigen genes in human colon tumor and normal fibroblast cell lines. CEA expression was not detectable in the normal fibroblast cell lines, whereas varying levels of high CEA expression were found in the colon tumor cell lines LS-174T, GEO, and WIDR. We have used a 550-base pair CEA probe derived from cloned complementary DNA to carry out Southern analysis of the DNA isolated from the normal and colon tumor cell lines. At high stringency, the CEA probe detected seven BamHI fragments in all DNAs analyzed. At low stringency, however, 14 BamHI fragments ranging from 1.5 to 23 kilobases were detected. Results of the Southern analysis demonstrate no amplification or rearrangement of the CEA genes in tumor cells. We used methylation-sensitive restriction endonucleases, HpaII and HhaI, to compare the degree of methylation of CEA family of genes in normal and colon tumor cell lines. Our results demonstrate that the CEA family of genes exists in a state of hypermethylation in the normal cell lines. In contrast, the CEA gene(s) are relatively hypomethylated in the tumor cell lines, suggesting a correlation between the state of methylation and degree of expression of the CEA gene(s). A comparison of the state of methylation of the CEA gene(s) in cells before and after treatment with the gamma-interferon (which up-regulates CEA steady-state mRNA levels) showed no detectable difference in the degree of DNA methylation. The segments of CEA genes that are hypermethylated in normal cells, but are hypomethylated in tumor cells, were also identified. Thus, these studies may help identify the sites of methylation that are crucial for the control of CEA gene regulation.

Antibodies, Monoclonal↗
PubMed1988

Common acute lymphocytic leukemia antigen is identical to neutral endopeptidase.

We purified CALLA from human kidney and isolated a cDNA clone reactive with two oligonucleotide probes corresponding to two distinct peptides. The amino acid sequence translated from the CALLA cDNA revealed 100% identity with that of human neutral endopeptidase (NEP, enkephalinase). The distribution of CALLA antigen and NEP in normal tissues are similar.

Amino Acid Sequence↗
PubMed1988

Enhancement of surface antigen expression on human breast carcinoma cells by recombinant human interferons.

Eight different human breast carcinoma cell lines, as well as clonally derived cell lines, were used to study the expression of four different monoclonal antibody (MAb)-defined tumor-associated antigens (TAAs) and the ability of recombinant human (rHu)-interferon (IFN)-alpha A and rHu-IFN-gamma to increase tumor-associated and/or normal cell-surface antigen expression. The different breast tumor cell lines expressed a wide range of antigenic phenotypes with respect to four different cell-surface TAAs. The cell lines could be divided into high and low antigen-expressing groups based on their constitutive levels of the four TAAs. In general, those breast tumor cell lines that expressed high levels of carcinoembryonic antigen, the MAb DF-3-defined 290-kD antigen, and the 90-kD antigen reactive with MAb B6.2 were poor candidates for antigen augmentation by rHu-IFN-alpha A or rHu-IFN-gamma. In contrast, breast cell lines that constitutively express low levels of these TAAs were found to be highly responsive to the ability of either of the rHu-IFNs to enhance MAb binding to the cell surface. Treatment with either of the rHu-IFNs increased the level of surface binding of MAbs as much as fourfold. The relative abilities of the IFNs to increase MAb binding to the surface of human breast tumor cells thus appeared to depend on the degree of constitutive surface antigen expression of the breast tumor cells. The high-molecular-weight TAA, TAG-72, is known not to be expressed on most cell lines but is expressed on the majority of human carcinoma biopsies. Most breast tumor cell lines employed in this study did not express the TAG-72 high-molecular-weight TAA. However, rHu-IFN-alpha A did substantially increase the level of expression of TAG-72 on the surface of breast tumor cells that were isolated from a pleural effusion. These studies may thus provide an important insight into the criteria used in the selection of carcinoma patients for IFN-mediated antigen augmentation when employing MAb-guided radioimmunolocalization or MAb-guided therapy.

Antibodies, Monoclonal↗
PubMed1988

Toxicity of polymerized hemoglobin solutions.

Four solutions of bovine polymerized hemoglobin (BPHS) and rabbit plasma were used to replace one-third of the blood volume in five groups of rabbits. The first three solutions were "impure" because of the presence of stromal phosphatidyl-ethanolamine and phosphatidyl-serine in BPHS-1, environmental endotoxins in BPHS-2, and a large amount of higher molecular weight hemoglobin-glutaraldehyde polymers in BPHS-3. These solutions caused a 33 per cent mortality rate and significant morbidity which was characterized by hemodynamic instability, respiratory and renal insufficiency, elevation of hepatic enzyme levels, thrombocytopenia, leukopenia, disseminated intravascular coagulation (DIC) and activation of the alternate pathway of complement. Histopathologic changes found in the heart, lungs, liver, spleen and kidney were characterized by a combination of ischemic and inflammatory lesions. Fibrin thrombi were visible by immunofluorescence in the microcirculation. In contrast, the fourth solution (BPHS-4) was free of the aforementioned impurities; caused no deaths and minimal morbidity, which was limited to elevated levels of serum glutamic pyruvic transaminase and reduction of creatinine clearance; no DIC or complement activation, and mild histopathologic changes which were exclusively ischemic in nature. The results of this study indicated that the toxicity of polymerized hemoglobin solutions is due principally to the presence of impurities. Pure hemoglobin does exhibit mild toxicity when compared with a control solution which is most likely due to a vasoconstrictor effect of oxyhemoglobin.

Animals↗