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Biomedical subjects

A Acevedo

Publications and source records attributed to A Acevedo.

At least 55 records · Page 3Linked to original sources
PubMed1993

Variability in the expression of a beta 2-microglobulin epitope on hepatocytes in chronic type C hepatitis on treatment with interferon.

Cytotoxic CD8+ T lymphocytes recognize viral antigens in the context of human leukocyte antigen class I molecule coexpression by target cells. Analysis of beta 2-microglobulin reactivity is useful in evaluating changes in human leukocyte antigen class I antigen distribution. In this study we analyzed liver biopsy specimens obtained from 15 patients with chronic active hepatitis type C who underwent a clinical trial with recombinant interferon-alpha 2b. We comparatively studied by immunohistochemical analysis the expression of human leukocyte antigen class I antigens in frozen liver samples obtained before entry in the protocol and in specimens taken 8 mo after initiation of treatment. Six normal liver samples were used as controls. For immunohistochemical analysis, a panel of several human leukocyte antigen class I monoclonal antibodies, specific for beta 2-microglobulin or different heavy-chain determinants, was used. In addition, we included a novel monoclonal antibody (HP-1H8), characterized in this report, which is specific for a distinct beta 2-microglobulin epitope. On entry, mean serum ALT was 240 +/- 89 IU/L and mean Knodell's index was 9.9 +/- 2.4, whereas at the time of the second biopsy mean values had diminished to 45 +/- 22 IU/L and 4.7 +/- 3.0, respectively. Liver sections from controls and patients expressed human leukocyte antigen class I light- and heavy-chain determinants in hepatocytes, biliary duct epithelium, sinusoidal lining cells and lymphocytes. Remarkably, the beta 2-microglobulin epitope recognized by the HP-1H8 monoclonal antibody was undetectable on hepatocytes from normal livers but clearly evident on hepatocytes from patients with chronic active hepatitis C before interferon treatment. Positive staining was more intense in areas of piecemeal and lobular necrosis. Double immunostaining with a CD2 monoclonal antibody demonstrated that labeling with HP-1H8 was predominantly associated with T-cell infiltration. Interestingly, the reactivity of HP-1H8 with hepatocytes was diminished or disappeared in specimens obtained during interferon treatment; the pattern of reactivity then resembled that of samples from normal controls. Our data indirectly suggest that, in addition to the increased expression of human leukocyte antigen class I molecules on hepatocytes in viral infections, conformational changes may take place in these antigens. These changes can be revealed by immunostaining with the HP-1H8 monoclonal antibody. Interferon therapy could down-regulate this expression through its effect in reducing the histological activity resulting from the lysis of virus-infected hepatocytes by cytotoxic T cells.

Adult↗
PubMed1993

[Composite gastric lymphoma: MALT gastric lymphoma associated with Hodgkin's disease].

We report a case of MALT (Mucosa Associated Lymphocytic Tissue) gastric lymphoma which occurred in a 52-year-old woman, associated with Hodgkin's disease, Lymphocyte Predominant type, in epiploic nodes. Although many cases of composite lymphomas have been reported, we were not able to find cases of gastric MALT lymphoma associated with Hodgkin's disease. This is probably the first case reported in the literature.

Female↗
PubMed1993

Distribution of ICAM-3-bearing cells in normal human tissues. Expression of a novel counter-receptor for LFA-1 in epidermal Langerhans cells.

The LFA-1 integrin mediates its function in leukocyte intercellular interactions by recognition of at least one of its three identified counter-receptors, intercellular adhesion molecules 1 (ICAM-1), 2, and 3. The ICAM-1 molecule is expressed in an inducible-dependent manner by endothelial and epithelial cells, as well as by other cell types, including leukocytes. On the other hand, ICAM-2 is constitutively expressed mainly by endothelial cells. We have studied the tissue distribution of the ICAM-3 molecule by immunohistochemical staining of lymphoid and nonlymphoid organs. Only cells from the leukocyte lineage were found bearing the ICAM-3 antigen, showing a pattern of expression clearly distinct from those of ICAM-1 and ICAM-2. Interestingly, we have found that ICAM-3 is expressed by epidermal dendritic Langerhans cells as assessed by double immunostaining with antibodies specific for CD1. In contrast, staining of skin sections with anti-ICAM-1 and ICAM-2 antibodies showed an undetectable expression of these two molecules on Langerhans cells. However, CD1+ Langerhans cells localized in the paracortical area of dermatopathic lymph nodes expressed both ICAM-1 and ICAM-3 antigens. Our results indicate that ICAM-3 is the main LFA-1 counter-receptor in human resident epidermal Langerhans cells. ICAM-3 may have an important role in T-cell antigen stimulation driven by Langerhans cells during skin immune reactions.

Adult↗
PubMed1993

[Controlled circulatory blockade. Historical principles and future perspectives].

Von Esmarch described the method known as "Blutleere". A tourniquet is applied to the thigh of the extremity whose blood has been previously withdrawn. We demonstrate that patients with chronic arterial obstructive disease (CAOD) tolerate without damage an one hour circulatory transient blockade (CTB). This CTB is followed by a conspicuous and significant improvement of the pain free walking distance and of the ankle-arm quotient in patients with CAOD. Bier (8), who was a pupil of von Esmarch, developed the regional i.v. anesthesia of the limbs, which he obtained by injecting procain in a superficial vein of the limb excluded from circulation. We have proved that it is possible to reach the capillaries with such a regional i.v. injection. We administered reserpin and guanetidin obtaining a long lasting sympathetic blockade which we used with good results in the treatment of patients with distal types of arterial occlusion. The use of antibiotics, which we injected in this regional i.v. way in diabetic patients with foot phlegmone, brought a considerable improvement of the prognosis. Indications and contraindications of this procedure are discussed.

Anesthesia, Conduction↗
PubMed1993

[Effect of transient therapeutic occlusion on some hemodynamic parameters and walking distance].

The effect of a one hour lasting occlusion was studied by recording the ankle/arm pressure ratios at rest and during post-occlusive reactive hyperemia 30 min, 1 day, 3 days and 7 days after the procedure. Both parameters improved, reaching a maximum on the 7th day at which time the changes became statistically significant. Finally, a standardized walking distance test yielded a highly significant improvement when determined on the 7th day (mean increase in walking distance: 69%). Although the underlying mechanism is yet unclear, the positive therapeutic results and absence of side effects warrant further investigations to be focused on the mechanism as well as on practical implications related to the procedure itself to optimize the results.

Arterial Occlusive Diseases↗
PubMed1993

[Regional drug-induced sympathicolysis in patients with arterial occlusive disease].

Regional drug-induced sympathectomy is a modification of Bier's block technique. By applying this method skin perfusion in patients with occlusions of lower leg arteries or functional disturbance of peripheral circulation can be improved. Under optimal technical conditions effects of regional and surgical sympathectomy are comparable. Fluorescence angiography can be applied to assess the effectiveness of drug-induced as well as surgical sympathectomy.

Arterial Occlusive Diseases↗
PubMed1993

[Malum perforans diabeticorum: treatment with controlled circulatory blockade and regional intravenous administration of antibiotics].

Orthopedic deformations of the feet play an important role in the etiology of the foot ulcers of diabetic patients, together with neuropathy and vascular impairment. The employment of new techniques in the treatment of diabetic foot has considerably improved its prognosis. These are the transient circulatory blockade (TCB) and the regional intravenous antibiotic administration (RAA). This paper reports on the usage of these techniques in the treatment of 24 diabetic patients, 8 women with ages between 41 and 75 (mean 54.7) years, and 16 men with ages between 41 and 75 (mean 59.3) years who were operated on 29 opportunities because of foot ulcer. Most of the patients had different grades of foot infection. Neuropathy was present in all cases and a distal type of arterial occlusion was diagnosed in 8 cases. Foot surgery was performed under regional i.v. anesthesia associated with regional i.v. injection of 1 g Cefotaxine (Calaforan) in 250 ml saline solution which was administered through the same butterfly needle used for the regional anesthesia. The drainage of the foot infection was performed simultaneously with the orthopedic correction of the foot deformities. All patients healed without complications attributable to the bone surgery. Patients operated upon while complicated with foot phlegmons remained longer (31 days) in the hospital than those without infection (18 days). After a follow-up period of 4.7 (1 to 8) years there were 2 recurrencies and 3 patients developed new foot ulcers. All patients were using a normal, soft shoe. We conclude that the TCB and the RAA facilitate orthopedic surgery in diabetic patients with foot ulcers improving their life quality and prognosis.

Adult↗
PubMed1993

[Antibiotic concentrations after intravenous and retrograde intravenous injections].

In patients with peripheral arterial occlusive disease, it is difficult to attain an adequate antibiotic concentration in poorly perfused infected lesions. The antibiotic concentrations prevailing in the ulcer secretion with the different routes of administration were investigated in 7 patients. The patients received 1 g of cefotaxim on consecutive days: intravenously on the first day, intraarterially on the second day and by retrograde venous injection on the third day. Significantly higher concentrations in the secretion were found after retrograde venous antibiotic administration than after intravenous or intraarterial injection. Clinical experience up to now indicates that far better results of treatment can be attained if the antibiotic is administered by retrograde venous injection (in addition to the surgical measures required).

Biological Availability↗
PubMed1992

Enhancement of human neutrophil functions by a monoclonal antibody directed against a 19-kDa antigen.

A mouse IgG mAb termed P1C3 was raised against A23187-treated human peripheral blood neutrophils and has been shown to recognize an Ag with an apparent molecular mass of 19 kDa, herein named p19. This p19 Ag was weakly expressed at the cell surface of resting human peripheral blood neutrophils and monocytes, but its cell surface expression was dramatically increased upon activation of these cell types with different secretagogues, including FMLP, PMA, and the calcium ionophores A23187 and ionomycin. A large latent pool of p19 molecules became accessible by immunofluorescence flow cytometry after cell permeabilization of resting neutrophils. A practically total translocation of the intracellular pool of this p19 molecule to the plasma membrane was achieved under appropriate cell stimulation, which induced an almost total degranulation of neutrophil secretory granules. The p19 Ag was absent from platelets, PBL, as well as from the human promyelocytic cell line HL-60, the human promonocytic cell line U937, and the human lymphoid cell lines Daudi and Jurkat. The p19 Ag was also expressed by circulating and/or interstitial neutrophils and monocytes in distinct tissues examined. The mAb P1C3 was found to enhance several neutrophil responses, such as chemotaxis, cell adhesion, phagocytosis, and respiratory burst. These data indicate that the mAb P1C3 recognizes an intracellular Ag in human resting mature neutrophils and monocytes, which upon cell activation is translocated to the cell surface and is able to affect cell functionality.

Antibodies, Monoclonal↗
PubMed1992

Regulated expression on human macrophages of endoglin, an Arg-Gly-Asp-containing surface antigen.

Endoglin is an endothelial homodimeric membrane antigen containing the tripeptide arginine-glycine-aspartic acid (RGD), which is a recognition motif for adhesion receptors of the integrin family. We have investigated the expression of endoglin by monocyte/macrophage cells from different tissue compartments and at different stages of cell differentiation. Although endoglin is absent from peripheral blood monocytes, it is expressed by in vitro differentiated monocytes as determined by flow cytometry using the endoglin-specific monoclonal antibody 44G4 and 8E11. Furthermore, Northern blot analyses revealed a correlation between the presence of endoglin mRNA and the surface expression of the antigen by in vitro differentiated monocytes. Immunostaining of frozen tissue sections with the 8E11 monoclonal antibody demonstrated the presence of endoglin not only in the endothelium of all the tissues studied, but also on the interstitial macrophages present in the red pulp of the spleen. Using as a model of macrophage differentiation monocytic cell lines treated with phorbol esters, we found that the reactivity of the 8E11 monoclonal antibody is greatly increased on U-937 and HL-60 cells during their PMA-induced differentiation. These findings clearly demonstrate for the first time the regulated expression of the putative adhesion molecule endoglin by macrophages.

Antibodies, Monoclonal↗
PubMed1991

Differential expression of VLA-4 integrin by resident and peripheral blood B lymphocytes. Acquisition of functionally active alpha 4 beta 1-fibronectin receptors upon B cell activation.

Very-late antigen (VLA)-4(CD49d/CD29) constitutes the only member of the beta 1 integrin family that plays a role in the interaction of lymphoid cells with both extracellular matrix and endothelial cells through two identified ligands: fibronectin (FN) and VCAM-1, respectively. The expression and functional activity of VLA-4 has been studied in different maturation and activation stages of B cells from several cellular compartments. Resident B lymphocytes of different lymphoid organs were almost negative for VLA-4 as detected by both immunoperoxidase staining and flow cytometry analysis. However, a high expression of both chains of this heterodimer was observed when tonsillar B cells were activated in vitro with different stimuli, such as phorbol esters or Staphylococcus aureus Cowan I (SAC). Both nonactivated and in vitro activated B cells from peripheral blood constitutively expressed high levels of this surface antigen. The induced expression of VLA-4 after activation of tonsillar B lymphocytes was accompanied by the acquisition of the capacity to bind to a 38-kDa proteolytic fragment, containing the connecting segment I domain, of FN. Interestingly, nonactivated peripheral blood B cells were unable to attach to this FN fragment, in spite of their constitutive expression of VLA-4, and only acquired this functional capacity after cell activation with phorbol esters and SAC. This FN-binding acquisition was not affected by preincubation with inhibitors of protein and RNA synthesis. These results underline that the FN-binding activity of VLA-4 is dependent on processes affecting cellular activation as described for other members of the integrin family. By contrast, VLA-4-mediated homotypic aggregation of peripheral blood B cells could be triggered by anti-alpha 4 monoclonal antibodies independently of the cell activation state.

B-Lymphocytes↗
PubMed1991

Photoregulation of the Cat2 and Cat3 catalase genes in pigmented and pigment-deficient maize: the circadian regulation of Cat3 is superimposed on its quasi-constitutive expression in maize leaves.

We have investigated the accumulation of Cat2 and Cat3 catalase transcripts in 6-7-day postimbibition leaves of normally pigmented and pigment-deficient maize seedlings under different light regimes. In seedlings of normal inbred maize lines Cat2 mRNA accumulates to significantly higher levels in either continuous light or a diurnal light/dark cycle than in continuous dark. In contrast to the high levels of the Cat2 message observed in their wild-type siblings, carotenoid-deficient mutants accumulate Cat2 mRNA at barely detectable levels. Mutants deficient in chlorophylls, but having normal carotenoid levels, accumulate normal levels of Cat2 mRNA. This suggests that both light and carotenoids are required for the normal accumulation of the Cat2 message. The steady-state level of Cat3 RNA exhibits a dramatic diurnal variation when seedlings are grown under a 24-hr light/dark cycle. We have previously shown that this variation is at the level of Cat3 gene transcription and is under the control of a novel circadian rhythm. In this study we show that both pigment-deficient mutants and their wild-type siblings exhibit the normal diurnal pattern of Cat3 RNA accumulation. This indicates that photosynthetic pigments, allelic variation, and genetic background do not directly affect the temporal pattern of Cat3 accumulation in leaves. We observed, however, that when normal plants are grown in either continuous light or continuous dark, the Cat3 transcript in leaves is present at uniformly high levels throughout the 24-hr sampling period.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Northern↗
PubMed1991

Identification of natural killer (NK) cells in lesions of human cutaneous graft-versus-host disease: expression of a novel NK-associated surface antigen (Kp43) in mononuclear infiltrates.

We performed an immunohistochemical analysis of skin biopsies from 13 allogeneic bone marrow transplant (BMT) recipients, undergoing either acute graft-versus-host-disease (aGVHD, n = 8) or chronic GVHD (cGVHD, n = 5). A panel of different monoclonal antibodies (MoAb) was employed including anti-CD2, -CD3, -CD4, -CD8, -CD11b, -CD16, -CD56, and -CD57, as well as a recently described reagent (HP-3B1) specific for a novel natural killer (NK)-associated cell-surface antigen (Kp43). Our data indicate that in aGVHD lesions the proportions of CD2+ cells often exceeded those detected with anti-CD3 MoAb. Double labeling confirmed the presence of CD2+ CD3- lymphocytes and suggested the coexpression in some cells of CD2 and CD11b. When MoAb specific for non-lineage-restricted NK-associated markers were employed, anti-CD56 and -CD57 occasionally stained variable numbers of lymphocytes (means = 14.6% of mononuclear cells in 0.05 mm2, range less than 1-48% and means = 10.3%, range 2-25%, respectively), whereas no CD16+ lymphocytes were observed. In contrast, most samples consistently displayed substantial proportions of Kp43+ cells (means = 32.8%, range 12-63%), which appeared CD3- and were mainly located at the dermoepidermal junction. On the other hand, sections from most (four of five) cGVHD lichenoid lesions analyzed displayed lower proportions of Kp43+ and CD56+ cells. Our data point out the interest of the anti-Kp43 MoAb to identify NK cells in aGVHD lesions, suggesting their pathogenetic participation.

Adolescent↗
PubMed1991

[Severe ischemia of the hand. Treatment with regional intravenous sympathicolysis with reserpine].

Treatment of severe hand ischemia a associated to progressive systemic sclerosis and other disorders is controversial. We studied prospectively 45 patients, 41 female and 4 males, over an 11 year period. Age ranged from 16 to 73 years, mean 46. Underlying disease was systemic sclerosis in 30, CREST in 8, overlapping syndrome in 4, systemic lupus in 1 and non rheumatic vasculitis in 2 patients. Treatment consisted of intravenous injection of reserpine, 1 mg, at a superficial arm vein after controlled local circulatory block for 15 min. Regional anesthesia was required in 38 patients. Adequate follow up was obtained in 32 females and 2 males, receiving a mean of 3.1 therapy sessions (range 1 to 13). Morphologic improvement from 3.09 +/- 0.16 to 1.57 +/- 0.13 and functional improvement from 3.6 +/- 0.12 to 1.75 +/- 0.14 (5 grade scoring system), was observed (p < 0.001). These results correlate with adequate rehabilitation confirmed clinically.

Adolescent↗
PubMed1990

A novel functional cell surface dimer (Kp43) expressed by natural killer cells and T cell receptor-gamma/delta+ T lymphocytes. I. Inhibition of the IL-2-dependent proliferation by anti-Kp43 monoclonal antibody.

In the present study we describe a novel functional cell surface molecule, designated as Kp43, which is expressed among leukocytes by NK cells, TCR-gamma/delta + T lymphocytes, and some CD8+ CD56+TCR-alpha/beta + T cell clones. The Kp43 Ag is a 70-kDa disulfide-linked dimer, which migrates in SDS-PAGE under reducing conditions as a single 43-kDa band. Two-color immunofluorescence staining of fresh PBL revealed that only a fraction of CD16+, and of TCR-gamma/delta + T lymphocytes expressed the Ag. The analysis of TCR-alpha/beta + T cell clones showed that a small proportion (2 out of 20) weakly expressed Kp43 together with the CD8 and CD56 molecules. By immunoperoxidase staining of different tissues the anti-Kp43, reactivity was detected exclusively in lymphoid organs, where a minority of scattered cells was stained, and in some liver sinusoidal cells. Essentially all NK cells acquired Kp43 when stimulated with a B lymphoblastoid cell line. By contrast, the pattern of distribution of Kp43 remained stable upon in vitro culture of T-gamma/delta lymphocytes, thus delineating two subsets according to its expression. In lymphokine-activated killer populations, obtained by culturing either PBL or NK cells with high concentration of IL-2, most CD16+ and CD56+ cells became Kp43+. The Kp43-specific mAb inhibited the IL-2-dependent proliferative response of cultured NK and TCR-gamma/delta + T cells without affecting their non-MHC-restricted cytotoxicity. The partial inhibitory effect, which was mediated as well by pepsin digested F(ab')2 fragments, was lost upon reduction to Fab. The anti-Kp43 mAb did not interfere with the specific binding of IL-2 to its surface receptors. Altogether the data point out that the Kp43 dimer is involved in the regulation of the IL-2-dependent proliferative response of NK cells and a subset of TCR-gamma/delta + T lymphocytes.

Antibodies, Monoclonal↗
PubMed1990

[Concentration of cefotaxime in the exudate from ischemic ulcer after systemic and regional administration].

We evaluated the concentration of cefotaxime in the exudate from ischemic leg ulcers in 9 subjects with severe obstructive arterial disease. The administration of the drug was either systemic (1 g in 250 ml of saline given in 30 min) or regional at a vein of the foot while a tourniquet was applied at the level of the thigh during 30 min. Hygroscopic discs were used to collect samples of ulcer exudate at hourly intervals for 4 hr. Cefotaxime concentration was determined by HPL chromatography. A significantly greater concentration of antibiotic was obtained with regional as compared to systemic administration (46 +/- 16 vs 25 +/- 14, p less than 0.01) and a greater percentage of patients attained MIC 90. A stable concentration of the drug was observed during the 4 hr period indicating a decreased rate of elimination of the antibiotic from the ulcer tissue. Thus, regional administration of antibiotics affords greater concentration than systemic administration, for treatment of ischemic leg ulcers.

Adult↗