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Biomedical subjects

L Diaz

Publications and source records attributed to L Diaz.

At least 19 recordsLinked to original sources
PubMed2001

Deciduoid mesothelioma: a rare, distinct entity with unusual features.

An unusual case of deciduoid mesothelioma occurring in the anterior abdominal wall of a 30-year-old woman is reported. The patient had a palpable mass that was resected. The mass appeared largely cystic with solid areas. Histologically, the tumor cells appeared epitheloid with eosinophilic cytoplasm and prominent nucleoli. The tumor was positive for keratins and vimentin and negative for CEA and Ber-EP4. Electron microscopy showed features of mesothelial cells characterized by well-formed desmosomes and long, slender microvilli. In contrast to previously reported cases of deciduoid mesothelioma, this tumor developed in the abdominal wall and appears to have a benign course.

Abdominal Muscles↗
PubMed2000

Mast cells in chronic rejection of human renal allografts.

An increased number of mast cells (MCs) is found in renal specimens of patients with diseases associated with persistent chronic inflammation. MCs proliferation is partly dependent on the presence of T lymphocytes. Both chronic inflammation and T-lymphocytes are essential in the development of chronic rejection (CR), and probably for the infiltration of MCs. MC-derived products such as heparin, histamine, and serine proteases may be responsible for endothelial proliferation and excess collagen production by fibroblasts. In this study, a quantitative evaluation of the MCs infiltration in kidney allografts with CR is performed. The extent of renal fibrosis was analysed in samples stained with Masson's trichrome. To evaluate the potential relationship between MCs and fibrosis in CR we analysed 30 kidneys with CR (25 from nephrectomies and 5 from autopsies). Ten transplanted kidneys obtained from patients died by causes not related with rejection were used as controls. CR was graded according to the Banff schema, which assesses the degree of vasculopathy, tubular atrophy, interstitial fibrosis and transplantation glomerulopathy. Giemsa-stained sections and immunohistochemistry using anti-MC tryptase and c-kit monoclonal antibodies were used to detect MCs. The mean number of MCs per 20 high-power fields (HPF) in the transplanted kidney with CR was 101.8+/-15.3 in the renal cortex and 46.60+/-6.52 in the medulla. MCs were significantly more numerous in CR with respect to normal kidneys, both in the cortex (P<0.01; Mann-Whitney U test) and in the medulla (P<0.01; Mann-Whitney U test). There was a positive correlation between the number of MCs and extent of fibrosis (P<0.01; Kruskal-Wallis one-way anova test) and tubular atrophy (P<0.01). These results suggest that MCs may play a role in the process of development of interstitial fibrosis in CR.

Adolescent↗
PubMed2000

Human immunodeficiency virus reverse transcriptase base misincorporations can promote strand transfer.

A system to determine if HIV-reverse transcriptase (RT) base misincorporations can promote strand transfer was constructed. A donor RNA, on which RT-directed DNA synthesis was initiated, shared homology over a 119 base internal region with an acceptor RNA, to which DNAs initiated on the donor could transfer. Products completed on the donor in the presence or absence of acceptor were isolated and PCR was used to amplify these DNAs. PCR products were ligated into a vector which had this same region (near the N-terminus of the alpha-lac gene) removed. Transformed E. coli were screened in an alpha-complementation assay by blue-white phenotype analysis with white colonies scored as those with errors in plasmid-derived alpha-lac. The frequence of white colonies +/- standard deviations was 0.031 +/- 0.006 and 0.0037 +/- 0.009, for plasmids with inserts derived from donor-directed products synthesized with 100 microM dNTPs in the presence and absence of acceptor template, respectively. Statistical analysis indicated a lower white colony frequency in the presence of acceptor (p = 0.0025). The lower frequency with acceptor implies that a portion of the errors made on the donor are transferred to the acceptor suggesting that base misincorporations can induce strand transfer.

Base Pair Mismatch↗
PubMed2000

Long-term follow-up of residual mediastinal-hilar Ga-67 uptake after treatment for Hodgkin's and non-Hodgkin's lymphomas: what degree of Ga-67 uptake is significant?

PURPOSE: Ga-67 planar and SPECT images of 85 patients after treatment for mediastinal-hilar (M-H) lymphoma were reviewed retrospectively. Forty-seven patients had Hodgkin's disease and 38 patients had non-Hodgkin's lymphoma. The entire period was 7 years after diagnosis. The main goal was visual assessment of the significance of mild (grades 1 or 2) Ga-67 uptake in the M-H area as compared with Ga-67 uptake in bone marrow. METHODS: Residual Ga-67 mediastinal uptake after a complete course of chemotherapy or other treatments was defined as normal (no residual) M-H uptake, borderline (M-H residual uptake with intensity less than that or equal to the sternum, spine, or both), and abnormal (M-H residual uptake with intensity greater than that of the sternum or spine). RESULTS: Among the 38 patients (45%) with no residual M-H uptake, four (one Hodgkin's disease and three non-Hodgkin's lymphoma) experienced recurrence: two in the mediastinum and two in the abdomen. Among the 45 patients (53%) with borderline M-H uptake, five experienced recurrence: two in the mediastinum and three in other sites. The two patients (2%) with abnormal (M-H) uptake never responded to treatment. No significant statistical difference in tumor recurrence was found between no residual and borderline uptake (P = 0.21). CONCLUSIONS: Visual assessment of M-H Ga-67 uptake (without quantification) could be useful to differentiate active residual tumor from nonactive residual uptake.

Female↗
PubMed1997

Results of a BFM-based protocol for the treatment of childhood B-non-Hodgkin's lymphoma and B-acute lymphoblastic leukemia in Argentina.

PURPOSE: To report the feasibility and results of a study based on the BFM-ALL. NHL/86 protocol for B-non-Hodgin's Lymphoma (NHL) and B-Acute Lymphoblastic Leukemia (B-ALL) in Argentina. Design. Prospective, single arm, non-randomized trial. PATIENTS AND METHODS: From August 1988 to December 1993, 87 consecutive patients with B-NHL/B-ALL were admitted and 82 were eligible. The therapy was stratified according to stage. All patients received a cytoreductive prephase with cyclophosphamide and prednisone. Those with stage I-II were treated with three 5-day blocks of combined intense chemotherapy including dexamethasone, cyclophosphamidie, ifosfamide, cytarabine, teniposide, doxorabicin, and 500 mg/m2 of methotrexate as a 24 hour continuous infusion. Stage III received 6 blocks and those with stage IV/B-ALL received 6 intensified blocks in which 2 g/m2 of 24 hour continuous infusion methotrexate and vincristine were added. Triple intrathecal therapy was given for CNS prevention. After the first two blocks the response was assessed and those with a partial response were offered optionallya second look surgery or local radiotherapy. RESULTS: With a median follow-up of 38 (range 16-71) months, the event-free survival (pEFS) for the whole group was 0.69 (Stage I-II n = 16 pEFS = 0.94, stage III n = 50 pEFS = 0.66, Stage IV n = 7 pEFS = 0.43, B-ALL n = 9 pEFS = 0.66). Patients with stage III abdominal tumors who achieved a partial response by imaging studies after induction had a significantly higher risk of relapse than those with a complete response (p = 0.02). Relapse was the most frequent event Toxicity was mainly hematological. CONCLUSIONS: The application of this protocol was feasible in our setting and its results comparable to the German study. Patients with stage I-II had an excellent outcome. Those with stage III and B-ALL achieved an encouraging event-free survival, however those with abdominal tumors and partial response to induction chemotherapy fared less favourably. This strategy was less effective for patients with initial CNS disease.

Adolescent↗
PubMed1997

Depression in Latina mothers of children with mental retardation: a neglected concern.

Depression among 148 Latina women who have children with mental retardation was examined. Results showed that their depressive symptomatology was elevated, with almost half reporting negative experiences in excess of a commonly used cut-off for the Center for Epidemiologic Studies Scale (CES-D). Depression scores related to variables pertaining to the child, mother's health and level of acculturation, and aspects of stress and coping. When mothers were categorized in three groups by CES-D scores, discriminant analysis correctly classified 84% of the low and high group mothers. High CES-D membership was predicted by mothers' reporting more family problems, worse health, fewer interactions with English-speaking persons in their daily lives, and more negative feelings about parenting their child with mental retardation.

Adaptation, Psychological↗
PubMed1996

Strand transfer is enhanced by mismatched nucleotides at the 3' primer terminus: a possible link between HIV reverse transcriptase fidelity and recombination.

Strand transfer catalyzed by HIV reverse transcriptase (RT) was examined. The system consisted of a 142 nt RNA (donor) to which a 50 nt DNA primer was hybridized. The primer bound such that its 3' terminal nucleotide hybridized to the 12th nt from the 5' end of the donor. The 3' terminal nucleotide on the primer was either a G, A or T residue. Since the corresponding nucleotide of the donor was a C, the G formed a matched terminus and the A or T a mismatched terminus. The efficiency with which DNA bound to the donor transferred to a second RNA, termed acceptor, was monitored. The acceptor was homologous to the donor for all but the last 9 nt at the 5' end of the donor. Therefore, homologous strand transfer could occur at any point prior to the DNA being extended into the nonhomologous region on the donor. Strand transfer occurred approximately twice as efficiently with the mismatched versus matched substrates. The mismatched nucleotide was fixed into transfer products indicating that excision of the mismatch was not required for RT extension or transfer. Results suggest that base misincorporations by RT may promote recombination by enhancing strand transfer.

Base Sequence↗
PubMed1996

Disseminated microsporidiosis especially infecting the brain, heart, and kidneys. Report of a newly recognized pansporoblastic species in two symptomatic AIDS patients.

Microsporidia have emerged as important opportunistic AIDS pathogens of the alimentary, respiratory, and urinary tracts. Although nonhuman mammalian microsporidia infections typically include encephalitis, CNS microsporidiosis has not been reported in patients with AIDS. A 33-year-old white male and an 8-year-old black girl presented with seizures and declining mental status. Central nervous system (CNS) imaging studies revealed small peripherally and diffusely enhancing lesions present for at least 2 and 4 months before death, respectively. Both patients expired despite empirical anti-toxoplasma therapy. Their brains contained innumerable soft gray matter lesions that consisted of central areas of necrosis, filled with free spores and spore-laden macrophages, surrounded by microsporidia-infected astrocytes. The complete autopsy of the child also revealed necrotizing and sclerosing cardiac and renal microsporidiosis and infection of the pancreas, thyroid, parathyroids, liver, spleen, lymph nodes, and bone marrow. Infected cells included astrocytes, cardiac myocytes, epithelium, endothelium, vascular smooth muscle cells, hepatocytes, adipocytes, Schwann cells, and macrophages. Light and electron microscopic studies revealed pansporoblastic development within thick-walled sporophorous vacuoles of parasite origin. Although most similar to Pleistophora sp and Thelohania sp, this microsporidian is different from any known species. Microsporidiosis should be considered as the possible cause of a wide range of diseases in AIDS patients, including CNS, cardiac, and renal.

AIDS-Related Opportunistic Infections↗
PubMed1996

[Reproducibility of nuclear grade in breast neoplasm. A multicenter experience].

Nuclear grade is considered a valuable prognostic factor in mammary carcinomas. Since the histological diagnosis of most of these tumors is made by "non expert" pathologists, it was considered interesting to find out the reproducibility of general pathologists to define the nuclear grade. In order to do this, a series of 15 mammary carcinomas, 10 of them randomly selected and 5 because they were considered difficult to classify for nuclear grade, were examined separately by 10 general pathologists. In a first round of observation, each one of them graded the cases according to their own criteria as used routinely, and for a second round they followed a written guide. An analysis of variance was applied to the data and no significant differences were found between observers, neither in the randomly selected cases nor in the total series. The written guide, surprisingly, instead of lowering the differences, increased them. Analysis of the individual performance of observers showed two of them having a great variation between both rounds of observation, and this was considered to influence the results of the whole group. Interobserver performance to discriminate high grade tumors (G3) from the rest, showed a good correlation in all the participants. These results allow us to conclude that in this series, examined by general pathologists, an acceptable reproducibility was observed, specially when high risk tumors were being identified.

Analysis of Variance↗
PubMed1994

Interleukin-10 inhibits apoptotic cell death in infectious mononucleosis T cells.

T lymphocytes from patients with acute EBV-induced infectious mononucleosis rapidly die by apoptosis in vitro. Because human and viral IL-10 are likely to be induced during acute EBV infection and display a variety of functions on human T cells, we examined IL-10 effects on infectious mononucleosis T cell death. After 12 h of incubation in medium alone, only 35.6 (+/- 8.2%) of the originally seeded infectious mononucleosis T cells were viable. Addition of human IL-10 (100 U/ml) to T cell cultures significantly improved recovery of viable cells (71.3 +/- 6.2%, P = 0.0156). Viral IL-10 had comparable effects to human IL-10 in this system. Protection from death by human and viral IL-10 (100 U/ml) was dose dependent and continued over a 6-d culture period. The human IL-10 effect was neutralized by the anti-human IL-10 mAb 19F1. Morphology and analysis of DNA after separation on agarose gels showed that IL-10 inhibits loss of cell volume, chromatin condensation, and DNA fragmentation, characteristics of death by apoptosis. As assessed by [3H]thymidine incorporation, the T cells were not induced to proliferate by IL-10 above the level exhibited when first removed from blood. T cells protected from death by IL-10 proliferated to IL-2 and spontaneously killed sensitive targets as effectively as medium-precultured T cells. Thus, IL-10 promotes the survival of infectious mononucleosis T cells otherwise destined to die by apoptosis and may be critical for the establishment of immunologic memory after resolution of the illness.

Adolescent↗
PubMed1993

Natural history of coronary atherosclerosis using quantitative angiography in men, and implications for clinical trials of coronary regression. The Harvard Atherosclerosis Reversibility Project Study Group.

Previous studies of the natural history of coronary disease generally relied on estimates of percent stenosis derived from visual assessment of the coronary angiogram. In a study of 26 patients, serial quantitative angiography was performed 3 years apart to determine changes in both absolute measurements of the luminal diameter and relative percent stenosis. Initially, the mean minimal diameter of 74 coronary obstructions was 1.94 +/- 0.09 mm, the mean "normal" reference diameter was 3.06 +/- 0.11 mm, and the mean percent stenosis was 37%. At follow-up, there was a mild reduction of 0.12 +/- 0.04 mm (6%) in the minimal diameter (p < 0.005), and an increase in percent stenosis to 39% (p = 0.03). The average diameter of 85 arterial segments without a focal obstruction either initially or at follow-up showed mild but significant progression (-0.11 +/- 0.04 mm; p = 0.02). Using a minimal change of 0.27 mm in arterial diameter as a categoric variable, progression occurred in 26% of 74 arterial segments, no significant change in 65%, and regression in 9%. The only significant determinant of disease progression was the initial severity of disease. Obstructed arteries with a larger initial minimal diameter and presumably milder disease progressed more rapidly than did those with a smaller diameter (r = -0.42; p = 0.0002). There was no effect of age on the rate of progression (r = 0.02; p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1993

Relation of vessel wall shear stress to atherosclerosis progression in human coronary arteries.

The purpose of this study was to determine the relation between vessel wall shear stress and the rate of atherosclerosis progression. Quantitative angiography was used to calculate the change in coronary arterial diameter over 3.0 years in patients enrolled in the Harvard Atherosclerosis Reversibility Project pilot study (n = 20 arterial segments). Vessel wall shear stress was calculated by means of a validated finite-difference model of the Navier-Stokes' equation that assumes a coronary flow rate of 8 ml/sec. The correlation between vessel wall shear stress and the change in arterial diameter at multiple points (mean, 70) along the length of the artery was then calculated for each of the 20 segments with a focal stenosis. In 15 of the 20 arterial segments there was a significant correlation (p < 0.05) between low shear stress and an increased rate of atherosclerosis progression. A Fisher's z transformation was then used to combine the correlation coefficients from all 20 segments. Low shear stress was significantly correlated (z = 0.37 +/- 0.00074, p < 0.0001) with an increased rate of atherosclerosis progression. This serial quantitative evaluation of human coronary arteries is consistent with previous data that have suggested that low shear stress promotes atherosclerosis progression. Variations in local vessel wall shear stress may explain the previously reported near-independent rate of atherosclerosis progression in multiple lesions within the same patient despite exposure to the same circulating lipoprotein values and systemic hemodynamics.

Computer Simulation↗
PubMed1985

Brazilian pemphigus foliaceus autoantibodies are pathogenic to BALB/c mice by passive transfer.

Brazilian pemphigus foliaceus (fogo selvagem) is a cutaneous blistering disease endemic to certain areas of South America that has distinctive epidemiologic features suggestive of an infectious disease transmitted by an insect vector. Patients with the disease have antiepithelial autoantibodies, both circulating in the serum and bound to lesional epidermis. In order to examine the possible pathogenic role of these autoantibodies, IgG from the sera of these patients was purified and injected into the peritoneum of neonatal BALB/c mice. Thirty-four of 46 mice (74%) receiving parenteral IgG fractions from these patients developed cutaneous lesions that were identical to the human disease by clinical, histologic, immunologic, and ultrastructural criteria. High-titer Brazilian pemphigus foliaceus sera produced lesions more consistently and rapidly than low-titer sera. When injections were discontinued, new lesions ceased to appear and old lesions resolved. The extent of disease correlated with the titer of human antiepithelial antibodies detected in the mouse serum (z less than 0.01). Similar concentrations of IgG fractions obtained from sera of unaffected Brazilians living in endemic areas and from American donors did not induce disease when injected into littermates. These results establish that the antiepithelial autoantibodies play an important role in the pathogenesis of the cutaneous lesions in Brazilian pemphigus foliaceus.

Animals↗