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Biomedical subjects

L M Sena

Publications and source records attributed to L M Sena.

At least 37 records · Page 2Linked to original sources
PubMed1993

Role of monocytes in cryoglobulinemia-associated nephritis.

Several monocyte-macrophage functions were found to be defective in cryoglobulinemic patients. Nevertheless, monocytes actively phagocytizing cryoglobulins have been frequently found in kidney specimens from these patients. Whether subsequent degradation of the ingested immune material is effective, however, is still unknown. Monocytes from eight cryoglobulinemic patients (4 with active disease and associated nephritis and 4 inactive cases without nephritis) and eight normal controls of same sex and similar age were analyzed. Monocytes from patients with active cryoglobulinemia and associated nephritis were found to be able to ingest, but unable to catabolize, cryoglobulins, as shown by electron microscopy using gold-labeled goat IgG to human IgG and IgM in 18-hour cultured suspensions. Synthesis and maturation of monocyte cathepsin D, one of the most important lysosomal proteases, were analyzed in the same subjects. Purified monocytes were cultured in presence or absence of cryoglobulins for 18 hours at 37 degrees C in RPMI medium and labeled with 35S-methionine. The various forms of cathepsin D were separated by electrophoresis and visualized by fluorography. Results from cultures of monocytes from clinically active cryoglobulinemic patients with nephritis suggest that intracellular transport of newly synthesized cathepsin D was impaired and the release into the medium of precursor polypeptides of the enzyme enhanced in each experimental condition. Since procathepsin D is susceptible to activation in pathologic conditions lowering local pH (such as in inflamed tissues), these data suggest that monocytes from patients with active cryoglobulinemia and associated nephritis have a propensity to exert phlogistic effects via secretion of procathepsin D in tissues.

Adult↗
PubMed1993

Removal systems of immunoglobulin A and immunoglobulin A containing complexes in IgA nephropathy and cirrhosis patients. The role of asialoglycoprotein receptors.

BACKGROUND: Whereas the complex removal routes hypothesized for IgA containing immune complexes (IC) and macromolecules can be adequately analyzed by a recently proposed IgA1-IgG aggregate probe (Lab Invest, 66: 86-95), the relative significance of the asialoglycoprotein receptors in IgAIC clearance is still uncertain. EXPERIMENTAL DESIGN: The removal kinetics of 99mTc diethylenetriamine-pentaacetic acid-conjugated asialo alpha 1 acid glycoprotein (AAGP) and 123I-labeled IgA1-IgG aggregate were analyzed in 11 cirrhosis patients and 13 IgAN patients of comparable age. RESULTS: IgA1-IgG aggregate mean plasma clearance rate was delayed in IgA neuropathy (IgAN) patients (slope 0.038 minutes-1, range 0.027 to 0.053) compared with normals (0.047 minutes-1, range 0.038 to 0.053, p = 0.05). The liver was the main organ involved in the IgA1-IgG removal. When compared with normals, (34.3 minutes, range 29.8 to 42.2), the liver mean transit time (MTT) was significantly (p < 0.02) prolonged in IgAN patients (41.3 minutes, 33.6 to 52.3). Participation of spleen in clearance was observed in some patients and was almost invariably concurrent with normal clearance parameters. Conversely, 9 out of 11 cirrhosis patients had a remarkable splenic uptake, but the blood clearance rate was invariably delayed (0.022 minutes-1, 0.014 to 0.028, p < 0.003) and liver MTT extremely prolonged (122.4 minutes, 52.4 to 400, p < 0.003). In IgAN patients with delayed clearance of the IgA1-IgG aggregate, a distinct trend of progression towards renal failure was noted. AAGP clearance was also delayed in cirrhosis patients: slope = 0.166 minutes-1, 0.108 to 0.247, p = 0.05 as compared with both normals (0.230, 0.173 to 0.289) and IgAN patients (0.250, 0.184 to 0.254). Liver MTT in cirrhosis patients was extremely prolonged: 240.6 minutes, 132.5 to 400 minutes, p < 0.007 compared with both normals (90.0 minutes, 82.7 to 96.6) and IgA patients (92.2 minutes, 70.3 to 107.1). AAGP clearance parameters in normals and IgAN patients were not statistically different. MTT values of AAGP and IgA1-IgG aggregate were strictly related (p = 0.008), suggesting that asialoglycoprotein receptors are partially involved in the clearance of the IgA1-IgG aggregate probe. CONCLUSIONS: Some patients with IgAN have a prolonged circulation of an IgAIC miming probe, probably due to an impaired macrophage function. Other possibilities of prolonged circulation of IgAIC in these patients should imply an abnormal IgA glycosylation pattern that allows IC to escape from an effective asialoglycoprotein receptor system. In cirrhosis patients, all of the removal routes of IgA and IgA containing IC are greatly altered suggesting a causative role in the development of an associated, often clinically inapparent, glomerular disease.

Adult↗
PubMed1989

Clearance of polymeric IgA aggregates in humans.

Clearance of aggregated human secretory immunoglobulin A (AHS-IgA) was studied in nine patients affected by primary IgA nephropathy (IgAGN) and six normal volunteers from the medical staff. Samples of whole blood, erythrocytes, and serum were taken from 3 to 120 minutes after injection of 0.5 mg of 131iodine-labeled AHS-IgA. No significant radioactivity was recorded on erythrocytes. The clearance curve of AHS-IgA from the circulation, calculated by measuring trichloroacetic acid precipitable radioactivity in serum, was found to be biexponential with an initial fast component significantly prolonged in patients (mean half-time, 19.4 minutes, range, 14 to 26 minutes) compared with controls (mean, 12.2 minutes, range, 7.6 to 16.8 minutes; P less than 0.01). These data indicate that clearance of aggregated polymeric IgA does not involve the erythrocyte transport system and seems to be defective in IgAGN patients.

Adult↗
PubMed1989

Gluten-induced experimental IgA glomerulopathy.

The effect of alimentary gluten and of its lectin-like fraction gliadin in inducing IgA mesangial deposits in BALB/c mice was investigated. In the pilot study G1 (4 mice), G2 (4 mice) and G3 (6 mice) received ovalbumin, human gamma-globulins, and crude gluten, respectively. The antigens, 1 mg/ml, were given in drinking water for 14 weeks. G4 (20 mice) were fed with standard mouse fodder. Gluten, as well as other alimentary antigens, induced IgA mesangial deposits with intense IgA staining in each animal, however a positive IgA staining was also observed in 10 of 20 adult controls. Antigliadin IgA antibodies were detected in renal tissue eluates from gluten-immunized mice but were found in eluates from control animals too. IgA deposits and antigliadin IgA in renal tissue were also observed in 3 of 7 adult mice (G7) fed for 30 weeks with standard fodder, then for 1 month with a protein-free diet supplemented with 20% amino acids. Conversely, there were no IgA mesangial deposits or IgA anti-gliadin antibodies in renal eluates of 1- or 2-week-old mice (G5 and G6). For the definitive protocol, 4-week-old BALB/c mice were selected and fed with basal glutenfree diet. G8 (14 mice) did not receive any alimentary immunogen in the drinking water, whereas G9 (15 mice) and G10 (15 mice) received ovalbumin and gliadin, respectively. G11 (15 mice) had standard gluten-containing diet. IgA deposits semiquantified by immunofluorescence scores were found to be significantly greater in G9 and G10 than in G8 (Student' t-test p1 less than 0.003, Mann-Whitney test p2 less than 0.001 and p1 less than 0.01, p2 less than 0.007, respectively), and in G11 than in G8 (p1 and p2 less than 0.05). The presence of positive IgA staining (greater than or equal to 2/6 scores) was significantly less frequent in G8 in comparison to G9 (chi-square test p3 less than 0.002), G10 (p3 less than 0.02) and G11 (p3 less than 0.04). Total serum IgA were significantly higher in orally immunized G9 and G10 than in G8 control mice (p1 less than 0.005, p2 less than 0.002). Anti-gliadin IgA in circulation as well as in renal deposit eluates were significantly increased in gluten-eating mice (G10 and G11) as compared with the gluten-free control group G8. These observations indicate that gliadin does induce IgA immune deposits in BALB/c mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Coupling of the alpha 1-adrenergic receptor to a guanine nucleotide-binding regulatory protein by a discrete domain distinct from its ligand recognition site.

At rat hepatic membrane alpha 1-adrenergic receptors, the nonhydrolyzable GTP analogue p[NH]ppG causes a rightward shift of agonist competition curves and a loss of high-affinity binding. This p[NH]ppG effect is consistent with the involvement of a guanine nucleotide-binding regulatory protein (G-protein) in alpha 1-adrenergic receptor signalling. Although readily apparent in membranes prepared to avoid retention of endogenous nucleotides and activation of Ca2+-sensitive proteinases (+pi), this p[NH]ppG effect is not observed in membranes prepared without proteinase inhibitors (-pi), or in -pi membranes treated with Ca2+ (-pi, +Ca2+). In these various membrane preparations, different Mr forms of the receptor are also identified by photoaffinity labeling with [125I]CP65526, an aryl azide analog of the alpha 1-selective antagonist, prazosin, followed by SDS-polyacrylamide gel electrophoresis and autoradiography. Whereas a predominant Mr = 80,000 subunit is identified in +pi membranes, in -pi membranes a proteolytic Mr = 59,000 fragment is also observed. In -pi, +Ca2+ membranes, only this latter peptide is detected. To evaluate the ability of each of these forms of the receptor to couple with a G-protein, the effect of p[NH]ppG on the agonist-inhibition of [125I]CP65526 labelling was determined by laser densitometry scanning and computer analysis. At the Mr = 80,000 subunit, p[NH]ppG causes a rightward shift of agonist competition curves and a loss of high-affinity binding, even in -pi membranes. By contrast, agonist-binding at the Mr = 59,000 subunit is of low-affinity and was not affected by p[NH]ppG. These data indicate that the cleaved Mr = 59,000 fragment, while retaining hormone binding activity is unable to undergo G-protein coupling. Thus, the alpha 1-adrenergic receptor appears to contain a discrete domain necessary for G-protein coupling that is distinct from its ligand recognition site.

Animals↗
PubMed1986

Agonist-induced isomerization of the alpha 1-adrenergic receptor: kinetic analysis using broken-cell and solubilized preparations.

The affinity of agonists but not antagonists at hepatic membrane alpha 1-adrenergic receptors is temperature dependent; a 100-fold higher affinity is observed at 4 degrees C than at 37 degrees C. The relationship between these two agonist affinity states was investigated by using a strategy that allows the kinetics of this transition to be examined under equilibrium conditions. When competition assays are performed at 37 degrees C for varying intervals and the reaction mixture is then rapidly cooled by freezing, allowed to thaw, and further equilibrated at 4 degrees C, a rapid and progressive decrease (t1/2 of 1-2 min) in agonist affinity occurs, the extent of which is directly related to the incubation time at 37 degrees C. This decrease in agonist affinity is sustained as long as agonist is present but can be reversed by its subsequent removal. In contrast, no change in affinity is seen in identical experiments when antagonists are employed as the competing ligand. High-affinity binding of agonists is also demonstrated in short-term nonequilibrium experiments, indicating that the low-temperature incubations do not induce, but rather stabilize, a receptor conformation of high affinity for agonists. These findings suggest that the predominantly low-affinity binding of agonists to alpha 1-adrenergic receptors demonstrated in equilibrium studies at physiological temperatures may be the result of a ligand-driven decrease in affinity. Since the transition in receptor affinity for agonists occurs not only in broken-cell preparations but also after detergent solubilization of the membrane receptor, it most likely is due to an agonist-induced change in the conformation of the receptor protein per se.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Circulating Fc-receptor blocking factors in IgA nephropathies.

Twenty-one patients with primary IgA nephropathy, 7 patients with Henoch-Schönlein nephritis and 4 patients with IgA nephropathy associated to alcoholic liver cirrhosis were tested for Fc-receptor phagocyte function by measuring the clearance of radiolabelled IgG-sensitized erythrocytes in vivo and the immune phagocytosis by monocytes in vitro. Meanwhile IgG-, IgA-, IgA1-, IgA2-, containing immune complexes, the complement components C3, C4, C3d and the HLA-A, B, DR phenotype were determined. The patients with major urinary abnormalities were well discriminated from those with only minimal hematuria by a defective macrophage function (p less than 0.01) and high levels of IgA immune complexes (p less than 0.02). Since non HLA-A, B, C, DR phenotype was prevalent in patients who had defective Fc-receptor function, whereas a significant correlation was found between Fc-receptor impairment and levels of IgA immune complexes, it appears likely that circulating blocking factors, possibly related to IgA containing immune materials, may impair macrophage function in IgA nephropathies.

Adolescent↗
PubMed1984

Monocyte and macrophage Fc-receptor function in systemic vasculitis with renal involvement.

The Fc-receptor function of macrophages and monocytes was studied in 10 healthy subjects and 10 patients (5 in phase of clinical activity) affected by systemic vasculitis with histological evidence of renal involvement. Macrophage function was detected by measuring the clearance in vivo of IgG-sensitized 51Cr-labelled autologous red blood cells (RBC). In vitro immune phagocytosis of monocytes was analysed as a kinetic phenomenon by incubating IgG-coated RBC with nearly pure suspensions of peripheral monocytes. All 5 patients studied in phase of clinical activity showed a defective Fc-receptor function in both the assays, as compared with normal subjects. Since a good correlation was found between the in vitro and the in vivo methods, the use of this non-invasive in vitro procedure is proposed as a substitute for the radioactive in vivo techniques in monitoring the course of the above disease.

Antigen-Antibody Complex↗
PubMed1983

Interaction between the macrophage system and IgA immune complexes in IgA nephropathy.

In nine patients with IgA nephropathy, the function of the mononuclear phagocyte system was assessed by measuring in vivo clearance of anti-D coated red blood cells (RBC) and in vitro phagocytosis of sensitised RBC by monocytes. A strict correlation was found between in vivo macrophage function and in vitro monocyte phagocytosis. Statistical correlations were also found between in vivo clearance values and IgAIC and C3d values. A defective macrophage and monocyte function affects patients with major signs of clinical activity, highest IgAIC values, signs of complement activation and the most unfavourable clinical course.

Antigen-Antibody Complex↗
PubMed1981

[Influence of thyroid states on PGE2 biosynthesis].

Hyperthyroid and hypothyroid states were induced in the rat by daily injection of 3,3',5-triiodothyronine (T3; 33 microgram/100 g b. wt., ip for 6 days) or by thyroparathyroidectomy, respectively. Control animals underwent only a sham operation or received the T3 vehicle. In these experimental conditions the biosynthesis of PGE2-like substance was determined "in vitro" in the fraction obtained after centrifugation at 80,000xg for 60 min of pooled spleens (5). Assays of PGE2 activity were carried out on rat stomach strip preparations according to Vane (8). In a series of additional experiments the influence of thyroid states on the inhibitory activity exerted by Indomethacin, Oxametacine and Phenylbutazone on PGE2 biosynthesis was also evaluated. The results obtained indicate that the hyperthyroidism induces a significant increase of PGE2 production "in vitro" from added arachidonic acid (100% enhancement above the control values) while thyroparathyroidectomy is unable to interfere with such biosynthetic activity. In addition, the inhibitory effect of Indomethacin, Oxametacine and Phenylbutazone on PGE2 production is not affected by hyperthyroid state whereas hypothyroidism significantly limits the action of the mentioned non-steroid anti-inflammatory agents.

Animals↗
PubMedDate not supplied

Influence of gluten-derived fractions on chemiluminescence production by human neutrophils.

The effects of gliadin and glyc-gli on leukocyte chemiluminescence response were assessed in vitro. A dose-dependent increase in chemiluminescence response of neutrophils stimulated by zymosan was observed by using gliadin at concentrations ranging between 1 and 20 micrograms. By increasing glyc-gli concentration, a bimodal response was observed with an enhancement up to 50 micrograms/ml, followed by suppressive effects, which were again dose-dependent. The possible implications of these findings in human pathology are discussed.

Celiac Disease↗
PubMedDate not supplied

A solid phase enzyme immunoassay for the measurement of urinary albumin and the detection of microalbuminuria.

A test for the measurement of trace urinary albumin concentrations, which is suitable for the detection of microalbuminuria, was developed. The technique is an indirect enzyme-linked assay (ELISA) in which a fixed amount of anti-albumin antibody is placed into polystyrene tubes coated with human albumin, together with the urine sample to be tested. The albumin in the test specimen competes with the solid-phase albumin for binding to the added antibody. The test is precise (inter- and intra-assay coefficients of variation were 8.2% and 7.8%, respectively), accurate (mean recovery 102-106% for two human albumin preparations), and sensitive (detection limit 0.9 micrograms/ml). These characteristics are not dissimilar from those of the radioimmunoassay reported in the literature, with the advantages of being completely safe, easy to perform, and not requiring expensive equipment. Using this assay the urinary albumin excretion in 20 normal subjects was found to be 2.5 +/- 2.2 micrograms/min (range 0.9-7.5 micrograms/min) after 8 hours of bed rest and 4.5 +/- 5.7 micrograms/min (range 1.5-2.0 micrograms/min) after 8 hours of moderate physical activity.

Adult↗
PubMedDate not supplied

[Anti-GM1 and anti-sulphatide antibodies in systemic idiopathic vasculitis, systemic lupus erythematosus and mixed cryoglobulinaemia: Serum detection and clinical and electrophysiologic correlations].

BACKGROUND: In the last two decades increasing interest has been focused on the association between autoimmune polyneuropathies and high titers of anti-nervous serum autoantibodies. High titer of IgG anti-GM1 antibody could be detected in Guillain Barre' syndrome and in chronic painful axonal sensory immune-mediated polyneuropathy. The possible occurrence of anti-nervous autoantibodies in autoimmune diseases not limited to the nervous system is still under study. METHODS: We evaluated 29 patients with systemic lupus erythematosus (SLE), 19 with biopsy-proven renal involvement, 28 patients with mixed IgM-K/IgG polyclonal cryoglobulinaemia (18 with glomerulonephritis) and 19 with small-sized vessel ANCA-associated vasculitis (12 with renal involvement) by using a sensitive immunoenzyme method of autoantibody detection. RESULTS: Compared to controls (1/176+/-1/205; 1:204+/-1:103), we found a significant increase in plasma IgM and IgG anti-GM1 titers (1:643+/-1:531; 1:444+/-1:309) in SLE patients (p<0.0001). We also found IgM (1:3032+/-1:2844) and IgG (1:1560) anti-sulphatide titers to be higher than the control group (p<0.0001). Mean plasma IgM and IgG anti-GM1 titers of the cryoglobulinaemic patients were 1:524+/-1:403 and 1:501+/-1:415, respectively, once again higher than the controls (p<0.0001). Mean plasma IgM and IgG anti-sulphatide titers in this group were 1:1864+/-1:1189 and 1:1350 (p<0.0001). We found idiopathic systemic vasculitis patients to have significantly increased levels of anti-sulphatides IgG class autoantibodies (1:1400; p<0.0001). We found no correlation with the serologic markers for vasculitis or the clinical or histologic extent of renal involvement. Electrophysiologic studies revealed that in 38% of SLE patients (p<0.005), 61% of cryoglobulinaemic patients (p<0.01) and 42% of ANCA-related vasculitic patients (p<0.01) the abnormal titers of antineuronal antibodies were associated with clinical or subclinical evidence of neuropathy. CONCLUSIONS: In patients with systemic idiopathic or secondary vasculitis anti-GM1 and anti-sulphatide antibodies can frequently be found. Their presence should prompt an accurate neurological examination because these serologic abnormalities are significantly associated with neurologic, often subclinical, involvement. Antineuronal reactivity might be the epiphenomenon of primary phylogistic damage, which exposes normally segregated neuronal epitopes or be directly involved in triggering neurological injury.

Antibodies↗
PubMedDate not supplied

[Role of food antigens and alcohol in idiopathic nephritis with IgA deposits].

It is generally thought that antigens inducing the formation of IgA immune complexes in primary IgA nephropathy and responsible for mesangial immune deposits are of infectious and alimentary origin. To investigate the possible role of alimentary antigens in eliciting the IgA mucosal immune response we studied the reactivity and the formation of mesangial IgA deposits in rodents following different experimental conditions: a) on gluten-free diet and oral immunization with gliadin; b) on gluten and soya free diet and oral immunization with soya; c) on chronic alcoholic intoxication. We found that oral immunization with gliadin induced the formation of mesangial deposits of IgA similar to those observed in human primary IgA nephropathy. On the contrary, oral immunization with soya failed to induce the formation of similar immune deposits even though the lectin components in soya and in gliadin are similar. Chronic ethanol intoxication induced an increase in serum IgA against alimentary antigens suggesting an increase in intestinal permeability due to alcohol. Mean times we observed significant IgA mesangial deposits. Our experimental data suggest that alimentary antigens can play a significant role in inducing primary IgA nephropathy.

Alcoholism↗