A Barat

Fundación Jiménez Díaz, Madrid, Madrid, Spain

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Publications (86)221.25 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Acute interstitial nephritis is an infrequent cause of early allograft dysfunction. Prophylactic trimethoprim sulfamethoxazole (cotrimoxazole) is frequently prescribed early in the course of kidney transplantation. Herein we have reported a case of delayed graft function associated with eosinophilia in which the renal biopsy showed interstitial mononuclear infiltrates with abundant eosinophils. An initial methylprednisolone course failed to lower the serum creatinine, but renal function and eosinophilia persistently improved following cotrimoxazole withdrawal and a second course of steroids. Cotrimoxazole acute interstitial nephritis is an infrequent but treatable cause of kidney allograft dysfunction, which should be included in the differential diagnosis of delayed renal allograft function.
    Transplantation Proceedings 09/2011; 43(7):2502-4. · 0.95 Impact Factor
  • Medicine - Programa de Formación Médica Continuada Acreditado 06/2011; 10(82):5532–5541.
  • Fuel and Energy Abstracts 01/2011; 10(82):5560-5580.
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    ABSTRACT: Twenty-six cases of high-grade lymphomas with activation markers (CD30) classified and immunophenotyped according to the Kiel classification were studied to determine their fine structural features. Transmission electron microscopy showed in 17 cases anaplastic nuclear and cytoplasmic changes identical to those observed in Hodgkin's disease, it being impossible to determine by the morphology a B, T, or null nature. Four high-grade B-centroblastic and immunoblastic cases and five T-pleomorphic cases showed nuclear changes and cytoplasmic differentiation that suggested a T or B nature. An immunogold-labeling technique showed CD30-positive particles primarily in the Golgi complex and occasionally in the cell membrane.
    Ultrastructural Pathology 07/2009; 14(5):381-97. · 0.98 Impact Factor
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    ABSTRACT: Leishmania infection may be associated with immunecomplex-mediated glomerular injury. Contrary to immune-competent individuals, leishmaniasis in HIV patients is a chronic, relapsing disease. Despite the increasing frequency of the Leishmania/ HIV co-infection, there is a paucity of information on the effects of such co-infection in the kidney. We present a patient with AIDS and refractory, relapsing visceral leishmaniasis who developed nephrotic syndrome associated with renal involvement by Leishmania in the absence of immunecomplex glomerular deposition. For the first time, the relapsing nature of renal injury in this context is documented.
    Clinical nephrology 08/2008; 70(1):65-8. · 1.29 Impact Factor
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    Nefrologia: publicacion oficial de la Sociedad Espanola Nefrologia 02/2008; 28(2):212-5. · 1.27 Impact Factor
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    ABSTRACT: Recurrent acute postinfectious glomerulonephritis is infrequent in childhood and exceptional in adults. The factors that determine recurrence are poorly understood. Selective IgA deficiency is characterized by an increased incidence of gastrointestinal and respiratory infections. The case of a 33-year-old man with a history of repetitive sinopulmonary infections and diagnosed with selective IgA deficiency is described. He suffered 2 episodes of postinfectious glomerulonephritis within a 15-year period. Selective IgA deficiency may have predisposed to the development of recurrent postinfectious glomerulonephritis
    Clinical nephrology 08/2006; 66(1):51-3. · 1.29 Impact Factor
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    ABSTRACT: The role of infiltrating cells (I.C.), commonly observed in the adenoma interstitial tissue, is unknown. We tested the hypothesis that I.C. are related with BPH progression by: phenotypically characterising these cells; quantifying the expression of lymphokines and growth factors; investigating the response to Permixon (P) in a clinical study. Permixon is a lipido sterolic extract of Serenoa repens possessing pharmacological activities and widely used in the treatment of men with BPH. A multicenter open pilot study of two parallel groups on BPH patients was carried out. They were randomized to receive either oral Permixon (P) 160 mg bid for three months or to be followed for 3 weeks without any treatment before surgery (control group C). Strict inclusion and exclusion criteria were applied to conform homogeneous groups, avoiding interferences of inflammatory drugs or others. Baseline clinical profile was almost identical in both groups in terms of age (65.7+/-5.1 vs. 67.1+/-5.8 years), IPSS (19.8+/-6.1 vs. 19.0+/-5.8), prostate volume (64.8+/-18.9 vs. 71.5+/-29.3cc), Q(max) (9.6+/-3.2 vs. 10.6+/-2.6 ml/s), and Q(L) (4.0+/-1.1 vs. 3.5+/-0.7). Surgery was ultimately performed on 29 patients (17C, 12P) by TURP or retropubic adenomectomy. Adenoma samples were routinely stained with HE and later prepared for immunohistochemical studies using CD3, CD20 and CD68 antibodies. Counting of positives cells, lymphoid aggregates and foci were done using EnVision technique and the Tech Mate processor. Cytokines, growth factors and eicosanoids were determined by Elisa kits following the manufactured recommendation. HISTOLOGICAL: A difference was observed in the number of lymphocytes B between C (91.4+/-44.1) and P treated (58.2+/-53.7) groups (p=0.097). BIOLOGICAL MARKERS: TNFalpha and IL-1beta were dramatically lower in the Permixon treated group. Other parameters did not show significant changes. CLINICAL: IPSS in the Permixon treated group was significantly reduced (p<0.006) from 20.0+5.9 to 14.9+3.8 after three months of treatment. The BPH inflammatory hypothesis was tested in humans. Our pilot study shows a significant reduction of some inflammatory parameters in prostatic tissues of patients treated with Permixon. These biological findings justify a pharmacological effect of this drug on the inflammatory status of the adenoma. A correlation with clinical improvement was observed.
    European Urology 11/2003; 44(5):549-55. · 10.48 Impact Factor
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    ABSTRACT: To electrophysiologically characterize alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)/kainate receptors in chick retinal membrane fragments, incorporated into Xenopus oocytes by direct microinjection. A 6-day retinal membrane suspension was injected into Xenopus oocytes by use of an electronic nanoliter injector. Fifteen to 40 hours after injection, the oocytes were assayed for kainate-elicited inward currents, under voltage-clamp conditions (membrane potential held at -70 mV). The structural incorporation of the retinal membrane fragments into the oocyte membrane was verified by specific immunofluorescent staining. Chick retinal membrane fragments were efficiently grafted onto Xenopus oocytes after microinjection, with 22.9% +/- 7.6% of the oocyte membrane being stained with anti-chick retina antibody. Part of the retinal material was seen as patches of relatively uniform size (292.1 +/- 72.3 microm(2)). Bath-applied kainate induced dose-dependent (EC(50): 64 +/- 7 microM), nondesensitizing inward currents (15-90 nA) in the chimeric Xenopus oocytes. Sham-injected oocytes did not respond to kainate. Kainate-driven currents were blocked by 6,7-dinitroquinoxaline-2,3-dione (DNQX) and 1-(4-aminopropyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine hydrochloride (GYKI 52466), but not by gamma-D-glutamylaminomethyl sulfonic acid (GAMS) or aminophosphonoheptanoate (AP7), suggesting the involvement of AMPA receptors in the observed responses. Guanine nucleotides (GNs) also blocked kainate currents in a concentration-dependent manner. An alternative oocyte microinjection technique to analyze the electrophysiological properties of glutamate receptors in chick retinal membranes is described. The results show the functional activity of putative AMPA-preferring receptors from chick retina and confirm, in the chick retinal model, the antagonistic behavior of guanine nucleotides toward glutamate receptors and their potential role as neuroprotective agents under excitotoxic conditions.
    Investigative Ophthalmology &amp Visual Science 08/2003; 44(7):3124-9. · 3.44 Impact Factor
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    ABSTRACT: The presence of mononuclear cells infiltrating the prostate adenoma is a morphological observation well established in the literature. However, its biological meaning is a subject of controversy. It has been postulated that it may represent a local immunological reaction contributing to the pathogenesis of prostatic adenoma. Several studies have been performed to test this hypothesis, both in humans and animals. The purpose of this review is to update available information, including our own ongoing studies. Morphological research has shown that cells infiltrating the adenoma are lymphocyte T, lymphocyte B and macrophages with a high proportion of lymphocyte T. Many of the inflammatory markers, such as lymphoquines (IL1, IL2, IL4, IL6, IL13), are elevated in the adenoma tissue as are some growth factors (EGF, TGF alpha, IFN gamma, TGF beta). The general impression is that an inflammatory process is activated in the adenoma during growth and maturing. It has also been proved that this inflammatory process could be modified with treatment and, in our case, with the lipido-sterolic extract of Serenoa Repens.
    Actas urologicas españolas 04/2002; 26(3):163-73. · 1.14 Impact Factor
  • J S Burgos, A Barat, G Ramirez
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    ABSTRACT: The aim of this study was to show that Cl(-)-dependent excitotoxicity, with its characteristic cell swelling, involves actual water influx into the intracellular compartment. Taking advantage of the Ca2+ omission paradigm of Cl(-)-dependent excitotoxicity, in the chick embryonic neural retina ex vivo, which is associated with toxicity levels (lactate dehydrogenase (LDH) release) considerably higher than those seen after simple exposure of the retinas to glutamate agonists, we have demonstrated that an intracellular water intake of 4.2 microl into retinal cells is associated with 13.3% total retinal LDH release. The fact that mannitol blocks both water inflow and LDH release appears to link both events from a pathogenic point of view.
    Neuroreport 12/2000; 11(17):3779-82. · 1.40 Impact Factor
  • J S Burgos, A Barat, G Ramirez
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    ABSTRACT: The chick embryonic neural retina ex vivo has been singled out as a unique example of Cl(-)-dependent/Ca2+-independent excitotoxicity. However, after continuous incubation with 100 microM kainate, we have demonstrated the susceptibility of the chick retina to Ca2+-mediated damage, which becomes apparent after 12 h of exposure to the agonist in the absence of Cl-. Of the 20.8% lactate dehydrogenase released after 24 h incubation with kainate, some 11% is Cl(-)-dependent and the rest (9.8%) is presumably Ca2+-dependent. Upon omission of both Cl- and Ca2+, a 5% residual toxicity can still be detected after 24 h. This can be overcome by inclusion of EGTA in the incubation medium to neutralize Ca2+ released during incubation. A Ca2+-dependent toxicity mechanism is then operative in the embryonic chick retina ex vivo.
    Neuroreport 12/2000; 11(17):3855-8. · 1.40 Impact Factor
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    ABSTRACT: AMPA (EC50 = 1.0 x 10(-6) M) and NMDA (EC50 = 1.3 x 10(-4) M) trigger 45Ca2+ influx in 13-day chick embryonic retinal explants. This agonist-driven cationic flux is specifically inhibited by typical competitive antagonists, such as 6,7-dinitroquinoxaline-2,3-dione (DNQX) and 2-amino-7-phosphonoheptanoate (AP7), respectively. Guanine nucleotides, with different degrees of phosphorylation, namely 5'-GMP, guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS), guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) and 5'-guanylyl-imidodiphosphate (GppNHp), are also efficient blockers of 45Ca2+ influx. These results confirm the antagonistic behavior of guanine nucleotides towards ionotropic glutamate receptors and suggest a convenient experimental approach for screening of novel agonists and antagonists.
    Neuroreport 08/2000; 11(10):2303-5. · 1.40 Impact Factor
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    ABSTRACT: Hepatitis C virus (HCV) infection has been associated with several renal pathologies, including membranoproliferative and membranous glomerulonephritis. Although the presence of HCV proteins has been reported, there are no data concerning detection of the viral RNA in renal cells from HCV-infected patients with kidney disease. In this report we analysed, by in situ hybridization, the presence of HCV RNA in renal biopsies from 10 patients who were positive for antibodies to HCV (anti-HCV) and serum HCV RNA positive, and from four patients without HCV infection, with different renal disease. HCV RNA was detected in the renal biopsies from all of the 10 HCV-infected patients. Hybridization signals were detected in the tubular and capillary endothelial cells. No hybridization signals were found in the renal biopsies of the four anti-HCV-negative patients. In conclusion, our results demonstrate that HCV RNA is common in kidney cells of patients with renal diseases who are infected with HCV. The presence of HCV RNA is not necessarily associated with a pathogenetic consequence.
    Journal of Viral Hepatitis 02/2000; 7(1):23-9. · 3.08 Impact Factor
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    ABSTRACT: Chick kainate binding protein was solubilized from cerebellar membranes and purified (x19) by use of two chromatographic steps. Measurements of [3H]kainate binding and GTPase activity in the different fractions reveal a consistent decrease of GTPase activity as the purification proceeds so that no GTPase is detectable after the final purification step. This fact, in the context of the differential involvement in nucleotide recognition of some critical amino acid residues in the p-loop motif of GTPases and in the guanine nucleotide-binding sequence of ionotropic glutamate receptors, together with significant discrepancies concerning the activity of individual nucleotides, suggests that both guanine nucleotide-recognizing sequences are unlikely to be alternative expressions of the same functional domain.
    Neuroreport 07/1999; 10(9):1981-3. · 1.40 Impact Factor
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    ABSTRACT: Injection of chick cerebellar membranes, rich in kainate binding sites, into Xenopus oocytes resulted in the structural integration of chick membrane patches into the oocyte plasma membrane that could be easily identified by specific immunofluorescent staining. Application of kainate to the oocyte perfusion medium, under voltage-clamp conditions, induced dose-dependent (EC50 = 87+/-14 microM) inward currents, confirming the functional incorporation to the oocyte of kainate-driven channels. Responses to kainate were consistently nondesensitizing and strongly potentiated by cyclothiazide, suggesting the selective involvement of alpha-amino-3-hydroxy-5-methyl-4isoxazolepropionate (AMPA)-preferring receptors. Binding experiments with (S)-[3H]AMPA confirmed the presence in the chick membrane preparation of low-affinity AMPA receptors (K(D) = 278 nM) amounting to <2% of the total population of kainate binding sites. A tenfold concentration of guanine nucleotides, with different degrees of phosphorylation, blocked the responses to 100 microM kainate by approximately 90%. In the case of GMP, additional concentration-inhibition studies yielded an IC50 of 180+/-11 microM. Our results illustrate the apparent failure of kainate-binding proteins to form functional channels, even when maintaining their own native membrane environment, and confirm the antagonistic behavior of guanine nucleotides, including GMP, toward glutamate receptors, in agreement with previous results of ligand-binding experiments and, more interestingly, with the marked neuroprotective effects of some guanine nucleotides in different excitotoxicity experimental paradigms.
    Journal of Neurochemistry 05/1999; 72(5):2170-6. · 3.97 Impact Factor
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    ABSTRACT: Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic growth factor (HGF) with many applications in cancer therapy. The most important applications are reduction in the incidence of febrile neutropenia, acceleration of neutrophil recovery after chemotherapy or bone marrow transplantation, and mobilization of progenitor cells. Many cutaneous adverse reactions associated with HGF have been reported in recent years, including injection site reactions, pyoderma gangrenosum, Sweet's syndrome, cutaneous leucocytoclastic vasculitis, and widespread folliculitis. The presence of large histiocytes on the dermis between collagen bundles has been proposed as a characteristic histopathologic finding in cutaneous eruptions secondary to granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor. We report on a patient with a high-risk ductal infiltrating carcinoma of the breast who received high-dose chemotherapy (HDC) with peripheral blood progenitor cell (PBPC) rescue. The patient received G-CSF after PBPC for a faster granulocyte recovery. She developed a cutaneous eruption located on back, buttocks, axillae, groin and sites where electrocardiography electrodes had been placed. From the histopathological point of view, the eruption was characterized by the presence of numerous large, atypical histiocytes in the dermis with several mitotic figures, mimicking involvement of the dermis by a malignant process.
    Journal of Cutaneous Pathology 12/1998; 25(10):559-62. · 1.77 Impact Factor
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    ABSTRACT: Cutaneous infections by nontuberculous mycobacteria (NTM) are not usual but their relative importance has changed during the last few years and still further changes are expected. This study comprised 13 patients from whom NTM were recovered from skin biopsy specimens, sinus exudates or cutaneous abscesses. All samples were processed according to standard methods, and the isolates were identified by biochemical testing. Skin biopsy specimens, when available, were processed for histopathological study. The clinical records of the patients were reviewed, and the relevant clinical, microbiological and epidemiological data collected. The clinical manifestations were noted to be relatively nonspecific and consisted of draining sinuses, abscesses, ulcers and nodules with multicentric or sporotrichoid patterns. Tissue culture isolated Mycobacterium fortuitum complex in nine patients, M. avium in three, and M. marinum in one. In the nine patients studied by histopathology, various patterns were observed. These included dermo-hypodermal abscesses, suppurative granulomas, tuberculoid granulomas and granulomas with a perifollicular distribution. Cutaneous lesions can thus be the first and the only sign of NTM disease, and culture still remains the definitive diagnostic procedure.
    Clinical and Experimental Dermatology 10/1998; 23(5):214-21. · 1.33 Impact Factor
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    ABSTRACT: Ex vivo preparations of chick neural retina have been successfully used in the assessment of excitotoxicity and in the evaluation of the protective effects of glutamate antagonists. Using a variation of this approach, and measuring the acute and delayed toxic effects of kainate (KA) in terms of lactate dehydrogenase release, we have shown that guanine nucleotides behave as effective neuroprotecting agents. The anti-excitotoxic potency of guanine nucleotides (in the case of GMP and GDPbetaS it is about 100 times lower than that of DNQX, a powerful kainate antagonist) correlates well with their ability to displace KA from retinal KA receptors.
    FEBS Letters 08/1998; 430(3):176-80. · 3.58 Impact Factor
  • L Requena, C Fariña, A Barat
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    ABSTRACT: Malignant atrophic papulosis is a rare disorder characterized by pathognomonic cutaneous lesions that consist of infarctive thrombosis. Visceral involvement often occurs; the gastrointestinal tract and the central nervous system are most frequently involved. Malignant atrophic papulosis has not been previously described in an AIDS patient. We describe a 58-year-old homosexual man with AIDS who developed typical cutaneous lesions of malignant atrophic papulosis. No visceral involvement has been detected in 2 years.
    Journal of the American Academy of Dermatology 06/1998; 38(5 Pt 2):852-6. · 4.91 Impact Factor

Publication Stats

577 Citations
221.25 Total Impact Points

Institutions

  • 1996–2011
    • Fundación Jiménez Díaz
      • Servicio de Nefrología e Hipertensión
      Madrid, Madrid, Spain
  • 1987–2011
    • Universidad Autónoma de Madrid
      • Department of Pathology
      Madrid, Madrid, Spain
  • 1999
    • Federal University of Santa Catarina
      • Departamento de Bioquímica
      Florianópolis, Estado de Santa Catarina, Brazil
  • 1991
    • Clínica Nuestra Señora de la Paz
      Madrid, Madrid, Spain