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Biomedical subjects

M D Lozano

Publications and source records attributed to M D Lozano.

At least 19 recordsLinked to original sources
PubMed2003

PTEN protein expression correlates with PTEN gene molecular changes but not with VEGF expression in astrocytomas.

PTEN gene (10q23) is a relevant tumor suppressor gene whose protein is a phosphatase involved in the control of angiogenesis of some tumors including astrocytomas. There are no studies correlating molecular changes of PTEN and the immunohistochemical expression of its protein (pPTEN) with the expression of vascular endothelial growth factor (VEGF) in astrocytomas. Fifty-six surgically resected brain gliomas, 10 grade 2, 16 grade 3, and 30 grade 4, were studied by a combined approach, consisting of (1) PCR analysis using four microsatellite markers against the PTEN gene region (10q23), (2) the FISH technique to test chromosome 10 using a pericentromeric probe, and (3) immunohistochemical evaluation of pPTEN and VEGF. Loss of heterozygosity (LOH) of PTEN was observed in 10% of fibrillary grade 2 astrocytomas and all gemistocytic ones. In high-grade tumors, LOH was more frequent in grade 4 than in grade 3 (> or =2 loci deleted, 83% and 56%, respectively). Monosomy for chromosome 10 was observed especially in high-grade tumors (6% of grade 3 and 50% of grade 4) and in 20% of grade 2 tumors, corresponding to gemistocytic astrocytomas. Results with both antibodies against PTEN were concordant: loss of cytoplasmic immunoreactivity was frequently observed according to homogeneous or heterogeneous patterns in 70% and 50% of grades 4 and 3, respectively, but not in grade 2. Immunonegativity of pPTEN was associated with PTEN gene deletion (> or =2 loci deleted) (P = 0.04) but not with monosomy. Cytoplasmic immunoreactivity against VEGF was observed in high-grade and in gemistocytic astrocytomas, but not in conventional grade 2 tumors. Tumor expression of pPTEN was not associated with immunoreactivity against VEGF when the same areas were considered. In conclusion, loss of PTEN expression is frequent in high-grade astrocytomas, but not in grade 2 tumors, and correlates with PTEN deletion and loss of chromosome 10. PTEN immunoreactivity does not correlate with VEGF expression in astrocytomas when similar areas are considered.

Astrocytoma↗
PubMed2001

Immunocytochemistry in the differential diagnosis of serous effusions: a comparative evaluation of eight monoclonal antibodies in Papanicolaou stained smears.

BACKGROUND: The distinction between pleural mesothelioma (MS), reactive mesothelium (RM), and adenocarcinoma (AC) in serous effusions continues as a diagnostic problem in pathology. Immunohistochemistry can help, especially in surgical samples, but the optimum panel of antibodies has yet to be reported. The application of these antibodies to serous effusions has displayed variable results. The aim of this study was to evaluate the usefulness of eight monoclonal antibodies in the differential diagnosis of MS, RM, and AC in serous effusions. METHODS: A total of 44 cytologic specimens of serous effusions (26 pleural, 15 peritoneal, and 3 pericardial) from 30 ACs, 3 MSs, and 11 RMs, previously stained with Papanicolaou stain, were selected retrospectively from our files and stained with HBME-1, thrombomodulin, calretinin, MOC-31, Ber-EP4, E-cadherin, CEA, and CD-15. The immunoreactions were evaluated independently by two pathologists. A stepwise logistic regression analysis was applied to the data to select an appropriate panel of antibodies. RESULTS: Statistical significance was found with HBME-1, thrombomodulin, MOC-31, Ber-EP4, and CD-15, when comparing both AC versus MS, and AC versus any type of mesothelial proliferation (MS or RM). Using HBME-1, 80% of ACs were negative whereas all three MSs reacted strongly with P = 0.003. A P = 0.02 was reached with thrombomodulin with 76.5% of ACs showing no immunoreactivity. Ber-EP4 and MOC-31 displayed good results with a P < 0.001 and 0.01, respectively. CD-15 reached a P = 0.034. No differences were found using the other antibodies. Ten ACs, all 3 MSs, and 10 RMs were double immunostained with HBME-1 and/or MOC-31 and Ber-EP4 successfully. CONCLUSIONS: Immunohistochemical studies performed on Papanicolaou stained cytologic smears proved to be useful in the differentiation between metastatic AC and mesothelial proliferation. HBME-1, thrombomodulin, MOC-31, Ber-EP4, and CD-15 were the most useful. In selected cases, it appeared that double immunostaining aided the differential diagnosis. Cancer (Cancer Cytopathol)

Adenocarcinoma↗
PubMed2000

Microvascular coronary arterial vasculopathy--predictive value of endomyocardial biopsy.

Graft arteriosclerosis (GA) is characterized as a diffuse, usually concentric, proliferative lesion of uncertain pathogenesis that occurs in the coronary arteries of cardiac allografts involving both the microvasculature and epicardial vessels, and represents the major limitation to long-term recipient survival. The whole length of the vessel is affected, including small distal intramyocardial branches, which precludes optimal treatment with routine revascularization procedures. The prevalence of GA at 5 years after transplantation is high. Early diagnosis of GA is limited by the lack of clinical symptoms for ischemia in the denervated allogaft, by the insensitivity of coronary angiography, which frequently underestimates the extent and severity of the disease, and by the exclusive or predominant involvement of small intramyocardial vessels in some cases. The introduction of intracoronary ultrasound imaging supports earlier pathological data indicating that coronary angiography underestimates the severity of the disease. The use of intracoronary ultrasound has improved the early diagnosis of large vessel disease, but it lacks accessibility to distal lesions; thus, the extent of intramyocardial small artery disease remains relatively unexplored. Although it has been proposed that EMB could provide useful information on the diagnosis and development of allograft vasculopathy, less attention has been focused on the small intramyocardial vessels, as they appear in the endomyocardial biopsy (EMB), nor on the significance of the myocardial pathology resulting from the perfusion defects caused by GA. The aim of this paper is to briefly review some of the pathogenic mechanisms responsible for the development of GA, and the pathological findings observed in the microvasculature of the myocardium with special attention to the lesions that can be noticed in EMBs.

Biopsy↗
PubMed1999

Utility of immunophenotypic and immunogenotypic analysis in the study of necrotic lymph nodes.

We report a case of complete lymph node necrosis. No specific aetiology could be determined by morphology, but a B lymphoid population and clonal rearrangement of the immunoglobulin heavy chain gene were demonstrated in immunophenotypic and immunogenotypic studies performed using DNA extracted from paraffin embedded necrotic tissue. In the setting of lymph node necrosis, we suggest that immunohistochemical and gene rearrangement studies may provide additional diagnostic information.

Female↗
PubMed1999

Decrease of apoptosis rate in patients with renal transplantation treated with mycophenolate mofetil.

BACKGROUND/AIMS: Mycophenolate mofetil (MMF) is a powerful immunosuppressant that inhibits the proliferation of lymphocytes by blocking the enzyme inosine monophosphate dehydrogenase. MMF prevents acute graft rejection in organ transplants. The aim of this investigation is to study whether MMF has any influence on apoptosis and proliferation rates of cells other than lymphocytes. METHODS: We conducted a retrospective study of renal allograft biopsies taken during the 1st week after transplantation in 25 patients receiving triple therapy with prednisone, ciclosporin and azathioprine 75 mg/day and in 25 patients treated with MMF at a dose of 2 g/day instead of azathioprine, in order to investigate the differences in the proliferation and apoptosis rates of the glomerular, tubular, interstitial and endothelial cells of the kidney. Twelve normal kidneys were used as controls. Conventional histopathological techniques were applied as usual for pathological diagnosis. Proliferative activity was assessed by use of MIB-1 antibody. Sections of formalin-fixed, paraffin-embedded tissue blocks were stained for the presence of apoptotic cells by TUNEL assay. Evaluation of proliferative or apoptotic rates was made by counting the number of positive cells in 10 glomeruli and in 10 transversely cut tubuli in each biopsy. The positive cells in the interstitium were counted in ten high-power fields. Positive cells in the endothelium were scored semiquantitatively from 0 to 3: 0 = none, 1 = isolated cells, 2 = small groups of cells, 3 = most endothelial cells. Mann-Whitney U and chi-square tests were used for intergroup comparisons. RESULTS: All biopsies were normal or had borderline (Banff classification) acute rejection. MIB-1 rates were similar in both groups, without statistical differences (p > 0.05) between them. Significantly lower apoptotic rates were found in the group treated with MMF in tubular epithelium (23.41 +/- 8.86 vs. 57.4 +/- 13.42; p = 0.021), in glomerular (1.25 +/- 0.78 vs. 5.3 +/- 1.66; p = 0.027), and interstitial cells (1.58 +/- 0.6 vs. 5.8 +/- 1.54; p = 0.043). Apoptosis in endothelial cells (p > 0.05) was similar in both groups. CONCLUSION: We conclude that treatment with MMF of kidney transplant patients does not affect the proliferative rate of cells of the allograft, but decreases the number of apoptotic cells in tubular epithelium.

Adult↗
PubMed1998

Molecular features in a biphenotypic small cell sarcoma with neuroectodermal and muscle differentiation.

We report a case of a 13-year-old girl with soft tissue sarcoma of the hand, which showed muscle and neuroectodermal immunophenotypes. Molecular studies were performed on RNA collected from fine-needle aspiration (FNA) cytology and peripheral blood samples by nested reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blot analysis. This biphenotypic tumor showed simultaneous expression of EWS-FLI1 and PAX3-FKHR transcripts, specific of Ewing family tumors and alveolar rhabdomyosarcoma, respectively. Although childhood sarcomas with simultaneous muscle and neural differentiation have been described to have EWS-FLI1 transcripts, there are no reports of tumors with both transcripts. Cytological specimens are a good source of RNA for molecular studies.

Adolescent↗
PubMed1998

Ewing family tumors: potential prognostic value of reverse-transcriptase polymerase chain reaction detection of minimal residual disease in peripheral blood samples.

In more than 95% of patients, the Ewing family of tumors (ET) has chimeric transcripts caused by fusion of the EWS gene to either FLI1 or ERG. The presence of specific EWS-FLI1 or EWS-ERG transcripts in peripheral blood (PB) samples of patients being treated for ET was prospectively evaluated, and these data were correlated to their clinical status. The authors studied 113 PB samples from 28 patients with ET. Treatment included chemotherapy, radiotherapy, and surgical excision of tumor after induction therapy. PB samples were taken prospectively at least 2 weeks after resection of tumor. Nested reverse-transcriptase polymerase chain reaction (RT-PCR) followed by Southern blot was performed in all samples. Resected tumors were reviewed for the degree of response to chemotherapy and volume. Seventy-seven PB samples from 28 patients had EWS-FLI1/ERG transcripts. In 11 patients, PB samples became negative with treatment, and, in 5 of them, the samples remained negative throughout the study. Samples taken during progression were always positive and, in 4 patients, became positive before progression was clinically evident. All patients with transcripts other than EWS-FLI1 type 1 (n = 3) died from tumor progression. This is a sensitive assay to monitor circulating tumor cells in Ewing tumors. The preliminary data suggest that progression is preceded by positive samples and may be related to specific transcript types.

Adolescent↗
PubMed1997

Human leukocyte antigen class II associations in patients with idiopathic dilated cardiomyopathy. Myocarditis Treatment Trial Investigators.

BACKGROUND: Idiopathic dilated cardiomyopathy (IDC) is a disease of unknown etiology for which immune abnormalities, possibly related to viral infections, are suspected but unproven. Previous serologic studies have reported associations between human leukocyte antigen DR4 and IDC. A molecular study of human leukocyte antigen associations was undertaken in patients with IDC to further explore the possibility of susceptibility markers of genetically determined disease. METHODS AND RESULTS: In this study, 36 patients from the Myocarditis Treatment Trial (32 IDC and 4 myocarditis patients) were examined using restriction fragment length polymorphism analysis and polymerase chain reaction amplification with sequence-specific primers to perform class II typing. All 4 myocarditis patients were DQ5 positive and 3 possessed the allele DQB1*0501. In the IDC group, the frequency of human leukocyte antigen DR4 was similar to that reported in the normal population. In addition, there was no excess prevalence of any molecularly defined DR4 alleles (0401-0419). There was an increase in the frequency of DR12 in IDC patients. The frequencies of the alleles DQB1 *0503 and DQB1*0301 and/or *0304 were also increased in IDC patients versus the normal population. CONCLUSION: The molecular studies point to a relationship between the DQ locus and IDC.

Adult↗
PubMed1997

Role of endomyocardial biopsy in the diagnosis of chronic rejection in human heart transplantation.

To assess the pathologic findings observed in the setting of post-transplant graft atherosclerosis, we have studied 18 endomyocardial biopsies (EMB) from 18 heart-transplanted patients collected at the same time that a coronary angiography (CA) showed changes consistent with graft atherosclerosis. Twenty-two EMB from patients with heart transplant with normal CA were used as controls. In spite of the small size of the sample, the number of acute rejection (AR) episodes correlated with the appearance of graft atherosclerosis (p < 0.001). Heart biopsies in graft atherosclerosis showed myointimal proliferation, thickening and folding of the wall of precapillary arteries, myocyte hypertrophy, and interstitial and perivascular fibrosis. Type III and type IV collagen, laminin, and fibronectin were increased in areas of interstitial and perivascular fibrosis, as well as in the vessel's wall. Fibronectin accumulation was more evident in the subendothelium and inner media of affected vessels. These changes were never found all together in control biopsies. Even though the inespecificity of some of those findings, we conclude that chronic graft atherosclerosis in a heart transplant may be suspected by endomyocardial biopsy when most of these alterations are seen together, especially if small precapillary arteries are present in the specimen.

Acute Disease↗
PubMed1996

Clonality analysis of B-lymphoid proliferations using the polymerase chain reaction.

BACKGROUND: Polymerase chain reaction (PCR) based assays are becoming more reliable, simpler, and faster alternatives to traditional Southern blot hybridization (SBH) analysis for the detection of clonal immunoglobulin heavy chain (IgH) gene rearrangements. However, a variety of technical approaches have been reported with markedly different results. METHODS: We analyzed the frozen tissue of 147 neoplastic and hyperplastic lesions on which SBH had previously been performed. Semi-nested and single-step PCR methods were compared. Consensus primers to the joining segments and the framework region (FR) III of the variable segments of the IgH gene were used. All PCR products were analyzed by polyacrylamide gel electrophoresis (PAGE). Thirteen samples were re-analyzed using a denaturing gradient gel electrophoresis (DGGE) system. RESULTS: The overall concordance between SBH and semi-nested PCR assays was 80.2%. In the non-Hodgkin's lymphoma (NHL) group, 75% of the cases with IgH rearrangements by SBH were found to be monoclonal by PCR. Regardless of type of lesion, 71.7% of the cases with IgH rearrangements by SBH were found to be clonal by PCR. The concordance between the semi-nested and single-step procedures was 87.1%. DGGE was helpful in clarifying the results for cases in which the PAGE analysis was difficult to interpret. CONCLUSIONS: PCR analysis of IgH gene rearrangements was found to be an efficient technique for the initial determination of clonality in lymphoid proliferations. The single-step method had an advantage over the semi-nested method because of its simplicity and speed. The DGGE system was useful for the assessment of clonality in cases with equivocal results after PAGE. However, a combination of these techniques in specific cases may achieve higher specificity and sensitivity.

B-Lymphocytes↗
PubMed1996

High-resolution analysis of immunoglobulin heavy-chain gene rearrangements using denaturing gradient gel electrophoresis.

The detection of clonality in B-cell lymphomas has been facilitated by polymerase chain reaction (PCR) analysis of the immunoglobulin heavy-chain gene (IgH) complementarity determining region 3 (CDR3) and size fractionation by polyacrylamide gel electrophoresis (PAGE). However, the detection of minor clonal populations and biallelic rearrangements and the isolation of monoclonal products from gels are sometimes problematic. This study evaluated whether denaturing gradient gel electrophoresis (DGGE), a technique that separates DNA based on nucleotide sequence rather than length, could alleviate these problems. A total of 32 selected cases was studied with a diagnosis of monoclonal (n = 10), polyclonal (n = 9), and indeterminate (n = 13) IgH gene rearrangements, which were determined by analysis of seminested IgH CDR3 PCR products in 8% PAGE. These cases were evaluated using DGGE of seminested IgH CDR3 PCR products that included a 40-bp GC clamp on the Jh primer. DGGE allowed the discrimination of monoclonal populations in 9 of 13 cases where 8% PAGE results were indeterminate. In addition, DGGE demonstrated biallelic IgH rearrangements in three cases where 8% PAGE revealed only one predominant product. DGGE facilitated the purification and isolation of clonal IgH CDR3 products for sequencing without prior cloning. As an adaptation of current IgH PCR protocols, DGGE can enhance the construction of tumor-specific CDR3 primers/probes for investigations of minimal residual disease.

Antibodies, Monoclonal↗
PubMed1995

Transcripts of the npm-alk fusion gene in anaplastic large cell lymphoma, Hodgkin's disease, and reactive lymphoid lesions.

Anaplastic large cell lymphoma (ALCL) and Hodgkin's disease (HD) have some pathologic and immunohistochemical similarities, and a histogenetic relationship between them has been suggested by some investigators. By cytogenetic study, the t(2;5)(p23;q35) translocation appears to be unique for ALCL. The breakpoints of the t(2;5)(p23;q35) have recently been cloned and are reported to involve a novel tyrosine kinase gene, anaplastic lymphoma kinase (alk), on chromosome 2 and the nucleophosmin gene (npm) on chromosome 5. Therefore, we studied the frequency of npm-alk translocation in ALCL using a reverse transcriptase-polymerase chain reaction (RT-PCR) assay. We also studied HD and a variety of reactive lymphoid lesions since there is contradictory information in the literature on the occurrence of the npm-alk rearrangement in HD. We detected npm-alk hybrid mRNA in 8 of 22 cases of ALCL (36%), but none of the 21 cases of HD or the 11 cases with reactive lesions contained amplifiable template. All positive ALCL had the T or indeterminate phenotype and occurred in young adults or children. There was very good correlation between a cytogenetically detectable t(2;5) and a positive signal by RT-PCR. Our results indicate a selective but relatively infrequent association between the t(2;5) and ALCL of T or indeterminate phenotype, not shared with HD or reactive hyperplasia.

Adolescent↗
PubMed1993

Local secretory IgA in dogs with low systemic IgA levels.

Low plasma IgA concentrations are commonly found in clinically normal dogs. In order to ascertain the relative importance of local and systemic IgA concentrations as factors determining the absence of clinical signs, IgA concentrations in plasma and tears were assayed in clinically normal dogs with a deficiency of IgA (10.33 +/- 0.63 mg/dl). The IgA levels in tears (25.28 +/- 1.91 mg/dl) did not differ significantly from those of control dogs or from previously published data for dogs. Thus, low systemic levels did not imply a significant reduction in local IgA levels. The absence of clinical signs in dogs with low plasma IgA concentrations may therefore be explained by the presence of normal secretory levels and an effective immune response against local pathogens.

Age Factors↗