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Biomedical subjects

M Garrido

Publications and source records attributed to M Garrido.

At least 19 recordsLinked to original sources
PubMed1992

A variant of Glanzmann's thrombasthenia which fails to express a GPIIb-IIIa related epitope that is recognized by a specific monoclonal antibody (C17).

Binding of different antibodies to the GPIIb-IIIa complex in resting (AP2, EDU3, C17) or activated platelets (PAC1) was studied by flow cytometry in a patient with a platelet defect involving GPIIb-IIIa related functions. The patient has a mild history of bleeding. Aggregation induced by ADP and collagen were absent but normal response was obtained with ristocetin. Platelets from the patient do not bind fibrinogen. Perfusion studies with flowing blood showed that patient's platelets have a marked impairment in the process of spreading and aggregate formation on vascular subendothelium. Electrophoretic studies in SDS-polyacrylamide gels demonstrated the presence of normal amounts and normal mobility of GPIIb-IIIa. Fibrinogen was present in the patient's platelets (68-74% of controls). The binding of AP2 and EDU3 to patient's resting platelets was normal as assessed by flow cytometry. In contrast, a decreased presence of the C17 antigen (10 fold lower than control platelets) was detected in resting platelets and a markedly reduced binding of PAC1 was found in thrombin activated platelets. These studies suggest that C17 recognizes an epitope of the GPIIb-IIIa in resting platelets that is implicated in the regulation of adhesive and cohesive properties of GPIIb-IIIa. Studies on this patient might be helpful for the understanding of GPIIb-IIIa functions.

Adenosine Diphosphate↗
PubMed1992

Plasma from systemic lupus erythematosus patients with antiphospholipid antibodies promotes platelet aggregation. Studies in a perfusion system.

The possible platelet-aggregating effect of plasma from systemic lupus erythematosus (SLE) patients (n = 19) was investigated under flow conditions. Aliquots of the SLE plasmas with (n = 10) or without (n = 9) anticardiolipin antibodies (ACAs) were added to anticoagulated blood (1:20, vol/vol). Plasma from normal donors was used as a control. Blood was incubated for 15 minutes at 37 degrees C and then perfused through annular chambers containing denuded arterial segments. Perfusions were performed for 10 minutes at a shear rate of 800 sec-1. The interaction of platelets with vessel subendothelium (SE) was morphometrically evaluated in thin sections. In control experiments, the percentage of the SE covered with platelets was 23.6 +/- 4.3% (mean +/- SD). Large aggregates (more than 5 microns in height) covering 11.8 +/- 5.7% of the exposed SE were noted. The deposition of platelets was statistically increased (38.5 +/- 7.6%, p less than 0.01 versus control) in the presence of SLE plasmas with demonstrated antiphospholipid antibodies (APAs). The formation of large aggregates was also augmented (30.3 +/- 5.9%, p less than 0.01 versus control). A similar response was obtained after addition of affinity-purified immunoglobulin G and immunoglobulin M fractions from two patients with ACAs. SLE plasmas with no detectable APAs did not influence the morphometric parameters studied. Results of the present study indicate that the presence of APAs in SLE plasma promotes platelet aggregation under flow conditions. These observations may help to explain the pathophysiology of the thrombotic events occurring in patients with APAs.

Adolescent↗
PubMed1991

Peroxisome proliferation and oxidative stress mediated by activated oxygen species in plant peroxisomes.

The existence of a relationship between clofibrate-induced peroxisome proliferation and oxidative stress mediated by activated oxygen species was studied in intact peroxisomes purified from Pisum sativum L. plants. Incubation of leaves with 1 mM clofibrate produced a remarkable increase in the peroxisomal activity of acyl-CoA oxidase and, to a lesser extent, of xanthine oxidase, whereas there was a nearly complete loss of catalase activity and a decrease in Mn-superoxide dismutase. Ultrastructural studies of intact leaves showed that clofibrate induced a five- and twofold proliferation of the peroxisomal and mitochondrial populations, respectively, in comparison with those in control leaves. Prolonged incubation with clofibrate produced considerable alterations in the ultrastructure of cells. In peroxisomal membranes, the NADH-induced generation of O2- radicals, as well as the lipid peroxidation of membranes, increased as a result of treatment of plants with clofibrate. In intact peroxisomes treated with this hypolipidemic drug, the H2O2 concentration was higher than in peroxisomes from control plants. These results demonstrate that clofibrate stimulates the production of activated oxygen species (O2- and H2O2) inside peroxisomes, as well as the lipid peroxidation of peroxisomal membranes. This effect is concomitant with a decrease of catalase and Mn-SOD activities, the main peroxisomal enzymatic defenses against H2O2 and O2-, and indicates that in the toxicity of clofibrate, at the level of peroxisomes, an oxidative stress mechanism mediated by activated oxygen species is involved.

Clofibrate↗
PubMed1991

Evaluation of the transfusion effectiveness of various platelet concentrates by means of an in vitro perfusion technique.

An in vitro perfusion technique was used for the assessment of the effectiveness of platelet concentrates (PCs) administered to patients with bone marrow failure. Denuded rabbit arterial segments mounted in annular chambers were exposed to nonanticoagulated blood drawn directly from the antecubital vein. This perfusion system allows the direct visualization of platelet-subendothelium interactions. The deposition of platelets on exposed subendothelium and the presence of fibrin were evaluated morphometrically. Perfusions were performed before and 10 and 120 minutes after the transfusion of PCs that had been obtained by apheresis and administered immediately after collection (A) or separated by centrifugation of blood units and transfused 24 hours after storage at 22 degrees C (B) or 4 degrees C (C). Bleeding times were also determined systematically. The deposition of platelets on the subendothelium increased significantly (p less than 0.01) 10 minutes after transfusions of A and B PCs, but the presence of fibrin did not differ from pretransfusion values. Two hours after the administration of A or B PCs, the improvement of platelet deposition persisted. By then, the presence of fibrin increased markedly (p less than 0.01). The deposition of platelets was not modified after the transfusion of C PCs, but the presence of fibrin was augmented significantly at both posttransfusion times. Comparisons between bleeding times and morphometric results pointed to a possible role of fibrin formation in contributing to primary hemostasis.

Bleeding Time↗
PubMed1991

Comparison between human umbilical artery and rabbit abdominal aorta as substrata for platelet adhesion and platelet thrombus formation under flow conditions.

Rabbit abdominal aortas and human umbilical arteries are currently used as substrata for the study of platelet adhesion and aggregate formation under flow conditions. Using immunohistochemical and ultrastructural methods, we have analyzed both vessel surfaces. The reactivity towards platelets of the subendothelium (SE) exposed on these vessels after mechanical or enzymatic digestion (alpha-chymotrypsin) was morphometrically quantified and the nature of the interaction studied in the electron microscope. After mechanical damage, the ultrastructural study of rabbit aortas showed a clearly defined internal elastic lamina (IEL). In contrast, umbilical vessels lacked a consistent IEL and masses of amorphous material often located deeper in the media were the main constitutents of the SE. Immunohistochemical labeling of the von Willebrand factor bound to both types of vessel differed considerably. Quantification of platelet interactions after perfusion of citrated blood showed qualitative differences between mechanically damaged rabbit or human vessels. Enzymatic digestion produced a more thrombogenic surface on rabbit aortas (p less than 0.01 vs. nondigested), but decreased their reactivity towards platelets on umbilical arteries (p less than 0.01 vs. nondigested). The ultrastructural study of the interacting platelets revealed that aggregates, when present, were found on the extracellular matrix underlying endothelial cells of rabbit aortas, but interacting with fibrillar structures probably derived from cell elements of the media in the case of umbilical arteries. These findings indicate that rabbit aortas and umbilical arteries possess structural characteristics that result in different thrombogenic properties with respect to circulating platelets.

Aorta, Abdominal↗
PubMed1990

[Effects of the treatment with human recombinant erythropoietin on primary hemostasis in uremic patients].

The effect of human recombinant erythropoietin (r-EPO) on primary hemostasia was studied in 9 patients undergoing hemodialysis. The analysis was performed before and after the hematocrit reached a value of 30%. The most important complications observed during the study period were a death for acute myocardial infarction in a patient with previous severe ischemic cardiopathy and a thrombosis of the venous line. The bleeding time shortened in four patients although the mean value did not change significantly. Platelet count showed a non significant increase. There was a significant improvement in in vitro platelet aggregability with ADP (p less than 0.05), arachidonic acid (p less than 0.05), adrenaline (p less than 0.05), and ristocetin (p less than 0.05) as well as in the parameters that quantify the interaction between platelets and subendothelium in in vitro experiments using perfused models (p less than 0.05). There were no significant changes in coagulation and fibrinolysis tests. The treatment with r-EPO improved primary hemostasia in uremic patients. This beneficial effect was due to the increased hematocrit and to the improvement of platelet function induced by r-EPO.

Adult↗
PubMed1990

Uremic platelets have a functional defect affecting the interaction of von Willebrand factor with glycoprotein IIb-IIIa.

Uremic patients have an impaired platelet function that has been related to membrane glycoprotein (GP) abnormalities. Using a perfusion system, we have studied the interaction of normal and uremic platelets with vessel subendothelium (SE) under flow conditions. Reconstituted blood containing washed platelets, purified von Willebrand factor (vWF) (1 U/mL), and normal washed red blood cells was exposed to de-endothelialized rabbit segments for 10 minutes at two different shear rates (800 and 1,600 seconds-1). In some experiments a monoclonal antibody to the GPIIb-IIIa complex (EDU3) was added to the perfusates. With normal platelets, the percentage of the vessel covered by platelets (%CS) was 23.1% +/- 3.7% at 800 seconds-1 and 30% +/- 4.3% at 1,600 seconds-1. Platelets were observed in contact or forming monolayers on vessel SE. EDU3 inhibited the spreading of normal platelets. The %CS (11.1% +/- 3.3%) was statistically decreased (P less than .01) and most of the platelets were observed in contact with the vessel surface. These data indicate that, under flow conditions, the interaction of vWF with GPIIb-IIIa can support the spreading of normal platelets in the absence of exogenous fibrinogen. Under the same experimental conditions, the interaction of uremic platelets with SE was markedly impaired at both shear rates studied (P less than .01 v normal platelets). The presence of EDU3 did not modify the interaction of uremic platelets. These results confirm the impairment of the platelet adhesion observed in uremic patients. Furthermore, they indicate the presence of a functional defect in the interaction of vWF with GPIIb-IIIa. The fact that perfusions with normal and uremic platelets in the presence of an antibody to the GPIIb-IIIa complex did not show any differences gives indirect evidence on a functionally normal interaction vWF/GPIb in uremic patients.

Blood Platelets↗
PubMed1990

[Correlation between IGA from colostrum and serum and IGA is closer than between salivary IGA and total IGA].

Colostrum, serum and saliva were simultaneously obtained from 50 normal mothers. 19-45 years old, 36-72 hours post-delivery. Total IgA level and class-IgA antibodies against 3 common food antigens (lactoglobulin, gliadin and ovalbumin) and 4 types of salmonella (typhi, paratyphi A, B and C) were determined in all samples. The 7 antibodies (Ab) were detected in colostrum, by ELISA, in a higher percentage of samples (88-62%), than in serum (82-34%) and saliva (77-27%). These percentages were higher for food-Ab than for anti-salmonella Ab. The total colostral IgA was close correlated with food-Ab in colostrum (p less than 0.001) and quite poorer with anti-salmonella Ab (p less than 0.05-p less than 0.01). A good correlation was generally also present between Ab from colostrum/serum, but was worse between both secretions (colostrum/saliva). The present results suggest that colostrum specific Ab levels can be predicted, depending on total IgA and the specific Ab from serum.

Adult↗
PubMed1989

Role for platelet von Willebrand factor in supporting platelet-vessel wall interactions in von Willebrand disease.

Twelve infusions of plasma concentrates of von Willebrand factor (vWF) were given to four patients with severe (type III) von Willebrand disease (vWD). Their prolonged bleeding times were either completely or partially corrected after five infusions and had not changed after the remaining seven. In contrast, the low platelet coverage of the subendothelial surface of rabbit aorta perfused with normal washed platelets and red cells resuspended in preinfusion patient plasma was completely or partially corrected in ten instances by replacing preinfusion plasma with postinfusion plasma and remained unchanged in two. Postinfusion improvement in surface coverage was greater than that in bleeding time, suggesting that vWF from normal platelets is needed to support optimal platelet-vessel wall interactions in vWD. This possibility was further explored through other perfusion experiments. The subendothelial surface covered by platelets from an untreated patient with type III vWD (containing no measurable vWF) or from a type IIA vWD patient (containing dysfunctional vWF) resuspended in normal plasma was much smaller than that covered by normal platelets resuspended in normal plasma. These results establish that platelet vWF is important in supporting platelet-vessel wall interactions in vWD and also provide experimental support in favour of the therapeutic transfusion of normal platelets in addition to vWF concentrates to correct the bleeding time in vWD patients.

Blood Platelets↗
PubMed1989

ADFR therapy in the prevention of bone loss after menopause.

Estrogens retard bone loss after menopause and constitute the most logical therapy for the prevention of postmenopausal osteoporosis. Estrogens are contraindicated in some circumstances and some postmenopausal women are unwilling to accept them. We have used ADFR therapy as an alternative in the prevention of postmenopausal bone loss. One hundred women in the early postmenopausal period (6-24 months since the last menses) were introduced into the study. 50 were treated with placebo and 50 were treated with ADFR therapy (phosphorus 1.5 gr/day during 3 days, followed by SCT 100 UI/day during 10 days and calcium 1 gr/day). After 77 days without any therapy we repeated the cycles every 3 months. Bone mass was evaluated at the beginning and at 3, 6, 12 and 18 months by dualphoton absorptionmetry lumbar spine. In the control group, the mean spinal BMD decreased 7.31% after 12 months and 6.16% after 18 months (p greater than 0.05). The ADFR group only had a mean spinal BMD decrease of 3.79% and 1.1% after 12 and 18 months respectively (NS). Bone loss was greater in control than in ADFR group after 12 and 18 months (p less than 0.05 at both times). We conclude that phosphorus and calcitonin like ADFR therapy may be a useful alternative to estrogen for the prevention of accelerated bone loss after menopause.

Aged↗
PubMed1989

Calcitonin reserve in healthy women and patients with postmenopausal osteoporosis.

A deficit of immunoreactive calcitonin (iCT) has been found in women with postmenopausal osteoporosis (PM-OP), however, recent studies assessing the monomeric fraction of calcitonin (exCT) do not seem to confirm these findings. We have measured serum levels of iCT by radioimmunoassay (RIA) and exCT (chromatography and RIA) at 0, 5, 10, and 20 minutes after the i.v. infusion of 2 mg calcium/kg body weight in four different groups of women: (1) 12 healthy premenopausal women (HPM), (2) 16 early postmenopausal women (EPM), (3) 16 postmenopausal women within more than 2 years of menopause (LPM), and (4) 24 women with PM-OP. In the HPM group, iCT levels increased significantly 5 and 10 minutes after finishing the calcium infusion (P less than 0.05); this did not occur in the other three groups. The exCT levels in the HPM and LPM groups showed a significantly greater increase than in the EPM and PM-OP groups at 5 minutes (P less than 0.05) and at 10 and 20 minutes (P less than 0.01) after infusion. The behavior of the PM-OP and EPM groups was similar throughout the study. We conclude that there is a calcitonin reserve deficiency in the first years after menopause, which recovers later. This hormone deficiency could explain the accelerated bone loss that takes place at this time of life. The patients with PM-OP also show this deficit, and this may play an ethiopathogenic role in the production of the disease.

Adult↗
PubMed1989

Synthesis, structure and cytostatic activity of a series of N-substituted 3,4-diphenyl-1H-pyrrole-2,5-diones.

A series of N-substituted 3,4-diphenyl-1H-pyrrole-2,5-diones (diphenylmaleimides) (IV) were synthesized and tested for cytostatic activity. Compounds IVa--k were prepared from diphenylmaleic anhydride or its dinitro derivative (V or VI) and the corresponding amine. Compounds IVl--n were obtained by reaction of 3-(p-nitrophenyl)-4-phenyl-1H-pyrrole-2,5-dione potassium salt with the appropriate chloroalkylamine. Hydrogenation of IVl,n gave the the corresponding cis-3-(p-aminophenyl)-4-phenylsuccinimides (VIIIa,b). The structure-cytostatic activity relationship of these compounds is discussed.

Antineoplastic Agents↗
PubMed1989

Uremic plasma after infusion of desmopressin (DDAVP) improves the interaction of normal platelets with vessel subendothelium.

Effects of 1-deamino-8-D-arginine vasopressin (DDAVP; 0.4 microgram/kg iv) were studied in 11 patients with uremia. Bleeding time, platelet retention on glass beads, factor VIII activities, plasma catecholamine levels, and studies on platelet interaction with the subendothelium were performed before, 1 hour after, and 6 hours after DDAVP infusion. Perfusates consisting of normal washed platelets, uremic platelet-poor plasma (u-PPP) and washed red blood cells were perfused through the Baumgartner perfusion system at a shear rate of 800 sec-1. One hour after DDAVP infusion, a shortening in the bleeding time and an increase in platelet retention on glass beads were noticed in these patients (p less than 0.01). Simultaneously, plasma levels of noradrenaline, factor VIII coagulant (FVIII:C), and von Willebrand factor (vWF) activities were statistically increased. Platelet deposition and platelet aggregate formation on subendothelium were consistently increased (p less than 0.05) in perfusions carried out with blood reconstituted with u-PPP obtained 1 hour after DDAVP. The "in vitro" addition of 1 U/ml vWF or 1 U/ml vWF plus 1 U/ml factor VIII to the pretreatment u-PPP had no significant influence on the parameters that quantify platelet-subendothelium interaction. However, after the addition of 10 ng/ml noradrenaline to a similar system containing basal u-PPP, a clear improvement (p less than 0.05) in platelet deposition was noticed. Our results confirm the hemostatic effectiveness of DDAVP in patients with uremia and reveal an increased platelet interaction with subendothelium mediated by a factor present in uremic plasma after DDAVP administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Left ventricular filling in sickle cell anemia.

M-mode echocardiography was performed on 11 normal black subjects and 38 patients with sickle cell anemia while they were at rest to evaluate their left ventricular (LV) systolic and diastolic function. The patients with sickle cell anemia were also evaluated by radionuclide exercise tests and, based on their ejection fraction (EF) response, were separated into 2 groups: a group with a normal EF response to exercise (73 +/- 9%, mean +/- standard deviation) and a group with an abnormal EF response to exercise (53 +/- 9%). Computer-assisted analysis of the M-mode echocardiograms identified abnormalities of diastolic function (impaired left ventricular filling) in patients with sickle cell anemia compared with the normal subjects. The abnormal EF response group had significantly more impaired diastolic function and did less exercise than the normal EF response group. Both groups of patients had a decrease in left ventricular end-diastolic volume during exercise. The patients with sickle cell anemia had abnormalities of systolic and diastolic function on echocardiographic and radionuclide testing. The abnormalities in diastolic and systolic function assumed greater significance at the increased heart rates associated with exercise, accounting for the decrease in left ventricular end-diastolic volume and the abnormal EF response, and contributed to exercise intolerance in patients with sickle cell anemia.

Adult↗
PubMed1988

Ristocetin induces platelet aggregation: a morphological demonstration.

Changes in the morphology of human platelets induced by ristocetin in platelet-rich plasma (PRP) have been analysed at the ultrastructural level by means of a tannic acid procedure. Studies were also undertaken to measure the release of serotonin. Modifications of the aggregation tests induced by apyrase, a monoclonal antibody (Mab) to GPIIb/IIIa and by EDTA were also investigated. Transmission electron microscopy revealed that ristocetin precipitated adhesive proteins on the platelet membrane. An electron-dense deposit was seen within 20 s after ristocetin was added. When experiments were carried out in the aggregometer cuvette during stirring, groups of platelets became activated, changed their shape, and finally aggregated releasing part of their contents. The morphology of aggregates did not differ from those formed in the presence of ADP. Aggregation studies demonstrated that a Mab to GPIIb/IIIa modified the extent and the rate of the aggregation curve when RIPA was performed in citrated platelet-rich plasma (c-PRP), while apyrase modifies the extent, but not the slope, of the curve. Neither the antibody nor apyrase modified RIPA when it was performed in PRP obtained in the presence of EDTA. All this evidence suggests that RIPA in c-PRP, besides reflecting the interaction of GPIb with vWF, may also test other mechanisms of the platelet function including: assembly of GPIIb/IIIa complex, interaction of fibrinogen with this glycoprotein complex, and possibly the release reaction.

Antibodies, Monoclonal↗
PubMed1987

Usefulness of radionuclide ventriculography in assessment of coronary artery spasm.

Provocative tests that permit detection of coronary artery spasm are widely used in patients with ischemic syndromes. To assess the usefulness of radionuclide ventriculography combined with provocative tests for diagnosis of coronary spasm, the left ventricular (LV) response to exercise, hyperventilation and a cold pressor test was determined in 3 groups. Group I included 10 normal subjects; group II, 49 patients with typical effort angina and fixed obstructive coronary artery disease at catheterization; and group III, 19 patients suspected of having vasospastic angina based on clinical and electrocardiographic findings, each of whom had normal coronary angiographic findings. In group I, LV ejection fraction (EF) increased during hyperventilation and exercise testing in 9 of 10 subjects (90%) and failed to decrease 5% in 9 of 10 subjects (90%) during cold testing. In contrast, while 18 of 49 patients (37%) of group II showed LV dysfunction with cold testing and 8% with hyperventilation, all showed abnormal LV function during exercise. Finally, in group III, LVEF increased during exercise, mimicking the response in normal group, while dysfunction was present in 14 of 19 (74%) during hyperventilation and in 17 of 19 (89%) during cold testing. When results of hyperventilation and cold testing were combined, abnormal responses were present in all patients. Thus, radionuclide ventriculography, when performed in association with 3 forms of stress--exercise, hyperventilation and cold testing--allows accurate identification of patients likely to have coronary spasm.

Adult↗