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Biomedical subjects

R Castillo

Publications and source records attributed to R Castillo.

At least 91 records · Page 5Linked to original sources
PubMed1991

Incidence of non-A, non-B hepatitis after screening blood donors for antibodies to hepatitis C virus and surrogate markers.

OBJECTIVE: To compare the effect of screening blood donors for antibodies to hepatitis C virus (anti-HCV) on the incidence of non-A, non-B hepatitis in recipients with that of screening blood donors for antibodies to hepatitis B core antigen (anti-HBc) and elevated alanine aminotransferase levels. DESIGN: Cohort analysis of serum samples from donors and recipients. Recipients were followed for 12 months to determine the occurrence of non-A, non-B hepatitis. SETTING: The blood-transmitted viruses unit and the liver unit of a university teaching hospital. SUBJECTS: A total of 250 patients who had open heart surgery and their 3142 blood donors. MEASUREMENTS: Donor sera were tested for anti-HCV by enzyme-linked immunosorbent assay (ELISA) and, in the event of a positive result, by recombinant immunoblot assay (RIBA). Antibodies to anti-HBc and serum alanine aminotransferase (ALT) levels were also measured. Measurements of anti-HCV and ALT activity in recipients were done before transfusion and at regular intervals during follow-up. MAIN RESULTS: Of the 250 transfusion recipients, 40 developed non-A, non-B hepatitis. Of the 3142 donors, 70 were positive for anti-HCV by ELISA, 440 were positive for anti-HBc, and 177 had alanine aminotransferase levels between 0.67 and 1.33 mukat/L. The sensitivity (87%), specificity (89%), positive predictive value (59%), and negative predictive value (97%) of blood-donor screening were higher for anti-HCV than for anti-HBc (82%, 36%, 21%, and 91%, respectively) and 70%, 29%, and 91%, respectively). The expected number of donors excluded because of the presence of anti-HCV was considerably smaller than that of donors with positive results for surrogate markers of hepatitis. CONCLUSION: Screening blood donors for the presence of anti-HCV is more accurate than screening for surrogate markers (anti-HBc and ALT) and protects more effectively against post-transfusion non-A, non-B hepatitis.

Alanine Transaminase↗
PubMed1991

Hemostatic effect of normal platelet transfusion in severe von Willebrand disease patients.

Platelet von Willebrand factor (vWF) has been suggested to play an important role in the hemostatic process. Clinical and experimental data indicate that bleeding time (BT) and platelet-vessel wall interaction cannot be normalized unless the defect of platelet vWF is also corrected. We have examined the effect of normal platelet concentrate transfusion 1 hour after cryoprecipitate infusion in five type III von Willebrand disease (vWD) patients. The cryoprecipitate infusion attained normal circulating levels of ristocetin cofactor, vWF antigen, and factor VIII activity. In two patients, cryoprecipitate infusion did not modify the BT (greater than 30 minutes), whereas in the remaining three patients BT was only partially corrected (from greater than 30 to 12, 18, and 21 minutes). However, the immediate platelet transfusion completely corrected the BT in four cases, and in one case it shortened the BT to 8.30 minutes (n = 3 to 8 minutes). In the perfusion study, cryoprecipitate infusion only resulted in a slight increase in platelet deposition (surface coverage range: 2.4% to 11.3%), whereas the platelet concentrate transfusion elicited a more marked improvement (range: 8.2% to 26.4%; P less than .02 v post-cryoprecipitate). These results suggest an important in vivo role of the platelet vWF in supporting platelet-vessel wall interaction. They also give support to the occasional addition of normal platelet transfusion to the cryoprecipitate infusion for the control of serious bleeding episodes resistant to cryoprecipitate in severe vWD patients.

Bleeding Time↗
PubMed1991

Immune hemolytic anemia and renal failure associated with rifampicin-dependent antibodies with anti-I specificity.

A 50-year-old woman with primary biliary cirrhosis developed immune hemolytic anemia and renal failure while receiving rifampicin for the treatment of refractory pruritus. Serological studies revealed the presence of rifampicin-dependent antibodies of the IgM class that, when tested against a wide panel of erythrocytes, had anti-I specificity. Subsequently, rifampicin was withdrawn and prednisone treatment instituted, this resulting in a rapid resolution of the hemolysis, whereas hemodialysis was required for recovery of the renal function. A role is suggested for the anti-I specificity of the antibodies in the development of renal failure associated with rifampicin therapy.

Anemia, Hemolytic↗
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

Methotrexate disposition following disruption of the blood-brain barrier.

Intracarotid drug administration after osmotic blood-brain barrier disruption (BBBD) enhances drug delivery to brain tumors. Despite clinical use, the pharmacokinetics of drugs following BBBD has not been described to date. Since methotrexate exhibits a concentration-toxicity response relationship, methotrexate disposition was determined following BBBD and intracarotid administration in seven patients with nonoperable brain tumors. Following a 1.5-5 g intracarotid methotrexate injection, 12 blood samples and 9 urine collections were obtained. Methotrexate concentrations in serum and urine were determined by fluorescence polarization immunoassay. The serum concentration-time data were best described by a three-compartment model. Systemic and renal clearances were consistent with previous studies. However, a prolonged mean terminal half-life of 51.5 h was observed. Serum methotrexate concentrations at 72 h exceeded 0.1 mumol/L in five of seven patients. Stomatitis occurred in one patient. Relative to previous reports, prolonged methotrexate half-life and cytotoxic methotrexate concentrations were observed in the serum of patients receiving intracarotid methotrexate following BBBD. Due to the prolonged cytotoxic methotrexate concentrations observed, extended leucovorin therapy may be indicated following BBBD and intracarotid methotrexate.

Adult↗
PubMed1991

[The abdominal complications of ventriculoperitoneal diversions].

We report several cases of abdominal complications in hydrocephalus children with ventriculoperitoneal shunts implanted by different ethnology, as well as the pathology produced. The number of children affected was 16, although some of them had suffered more than one complication, making up a total of 25 cases. The most frequent trouble was due to the intraperitoneal catheter fall, followed by intestinal perforation at different levels, allowing the catheter to get out through the anus, abdominal wall or surgical incision. Some intestinal occlusive situations was due to either volvulus or external compression caused by cerebrospinal fluid abdominal pseudocysts, secondary to ventriculoperitoneal shunt. We took different characteristics of this group of patients and studied the different complications in relation with specialized reports by international authors.

Abdomen↗
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

[Microangiopathic thrombotic syndromes in adults: results of treatment with intensive plasmapheresis].

The response to intensive plasmapheresis was evaluated in 13 patients (7 males, 6 females; median age 28 years) with microangiopathic thrombotic syndromes (MTS) who were treated at our center during the last 10 years. The most common initial clinical features were anemia, hemorrhage and neurologic abnormalities. Twelve patients had severe thrombocytopenia and 8 had renal failure. Fourteen plasmapheresis courses were carried out to treat 13 initial episodes and one relapse. The mean volumes of removed plasma and fresh frozen plasma infused at each exchange were 57 ml/kg and 41.7 ml/kg, respectively. Eight patients received antiplatelet drugs and/or corticosteroids. After a mean number of 10.6 exchanges per patient and course, complete remission (CR) was achieved in 7 cases (6 initial episodes and one relapse) and a partial response in 3. Four patients did not respond to therapy and died from progression of the disease. The early institution of plasmapheresis and the rapidity to respond were the only factors significantly associated with the achievement of CR.

Adolescent↗
PubMed1990

Investigation of plasma von Willebrand factor and circulating platelet aggregating activity in mitomycin C-related hemolytic-uremic syndrome.

We have studied the ability of the plasma to induce aggregation of both homologous and heterologous platelets in four patients with hemolytic-uremic syndrome (HUS) associated with chemotherapy with mitomycin C (MMC). Neither platelet aggregation was elicited by patients' plasmas nor the in vitro addition of purified von Willebrand factor (vWF) had any effect on the aggregation pattern. In addition, ristocetin-induced binding of patients' vWF to formaldehyde-fixed platelets was normal, and multimeric vWF analysis revealed a normal structure of patients' plasmatic vWF whatever the clinical stage in which it was studied. These findings suggest that, in spite of the existence of common clinical and biological features in the various forms of HUS, the pathogenesis of MMC-related HUS may be, at least in part, different from that of the other forms of HUS in which both platelet-aggregating activity and alterations in the vWF are found.

Blood Platelets↗
PubMed1990

Hepatitis C virus antibodies in chronic alcoholic patients: association with severity of liver injury.

The prevalence of hepatitis C virus antibody and its relationship to the severity of liver disease in chronic alcoholic patients has been assessed, using a recently developed enzyme immunoassay and confirmed by a recombinant immunoblot assay, in 144 patients (mean age +/- S.D. = 44.4 +/- 11.3 yr) who had consumed greater than 80 gm/day ethanol for greater than 5 yr. Hepatic disease was evaluated by clinical and biochemical studies and by liver biopsy when appropriate. In addition, 76 liver biopsy specimens from these patients were analyzed to determine whether liver lesions were similar in alcoholic patients with and without hepatitis C virus antibodies. According to clinical and histological features alcoholic patients were divided into five groups: normal liver (45 patients), fibrosteatosis (20 patients), alcoholic hepatitis (14 patients), cirrhosis (61 patients) and chronic hepatitis (4 patients). Hepatitis C virus antibodies were present in 35 alcoholic patients (24.3%). The prevalence of hepatitis C virus antibodies correlated with the severity of liver injury: 2.2% in patients without liver disease, 20% in those with fibrosteatosis, 41.4% in those with alcoholic hepatitis and 42.6% in those with cirrhosis. Hepatitis C virus antibodies were found in one of the four patients with chronic hepatitis (p less than 0.001). Furthermore, patients positive for hepatitis C virus antibodies with normal liver or fibrosteatosis showed higher serum bilirubin and gamma-globulin concentrations and lower aminopyrine breath test scores than did patients negative for hepatitis C virus antibodies with normal liver or fibrosteatosis. Similar differences between patients with and without hepatitis C virus antibodies were observed in patients with alcoholic hepatitis or cirrhosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Differential localization of von Willebrand factor, fibronectin and 13-HODE in human endothelial cell cultures.

Von Willebrand factor (vWF), fibronectin (FN) and 13-hydroxy-octadecadienoic acid (13-HODE) are known to influence the regulation of the adhesive properties of vascular surfaces. In the present study vWF, FN and 13-HODE were comparatively localized in endothelial cells (EC) and in the extracellular matrix (ECM) produced by EC. An indirect immunofluorescent technique was applied to coverslips containing human EC cultures previously fixed and permeabilized following different procedures: A. Alcohol/acetone; B. Paraformaldehyde alone and C. Paraformaldehyde followed by Triton X-100. vWF was observed inside EC (A), on the ECM produced by EC (B) or in EC and ECM (C) depending on the fixation procedures used. FN was mainly localized in the ECM despite the fixation procedures employed. FN was only seen in relation to cell bodies after strong permeabilization (A). Under our experimental conditions 13-HODE was never found in ECM. This latter antigen was observed randomly dispersed in those preparations fixed with alcohol/acetone, indicating that it is probably extracted by this fixative. 13-HODE was detected in granular shaped structures in EC after permeabilization with detergent (C). These results suggest that the cellular localization of vWF and FN is compatible with an adhesive role related to the abluminal side of ECs. 13-HODE was readily observed after mild permeabilization. This finding would be morphologically consistent with its contribution to the regulation of the vessel wall thromboresistance.

Cells, Cultured↗
PubMed1990

Alfentanil potentiates midazolam-induced unconsciousness in subanalgesic doses.

The effects of alfentanil on the midazolam dose-response curve for hypnosis was studied with response to the verbal command as an end point in 95 patients. The analgesic effect of alfentanil was studied by measuring the threshold for pain caused by pressure on the trapezius muscle with the use of a dolorimeter in 21 patients. The study was randomized, double-blind, and performed on the unpremedicated patients with ASA physical status I or II. Alfentanil was found to reduce the midazolam ED50 value for the induction of anesthesia in a dose-dependent fashion. The smallest dose of alfentanil (3 micrograms/kg) that caused a marked shift of the midazolam dose-response curve to the left along the dose axis (from the ED50 of 270 micrograms/kg to the ED50 of 142 micrograms/kg, P less than 0.0005) represents approximately 2% of the alfentanil ED50 for induction of unconsciousness (130 micrograms/kg). Alfentanil (10 micrograms/kg) caused only a tendency for increase in the pain threshold, whereas a dose of 15 micrograms/kg significantly increased the pain threshold by 37% (P less than 0.05). The results demonstrate that alfentanil potentiates the hypnotic effect of midazolam in very small doses. The high potency of alfentanil in this respect, as compared to its analgesic potency, suggests a very specific mechanism of alfentanil-midazolam hypnotic interaction, one that most likely is based on a functional relationship between the GABA receptor-benzodiazepine receptor system and the opioid receptor system in mediation of hypnosis.

Adult↗
PubMed1990

[Update on the role of vascular, plasmatic and cellular components in the regulation of the interaction of platelets with the subendothelium].

The interaction of platelets (Plts) with subendothelium (SE) or with extracellular matrices (ECM) generated by endothelial cells was studied under flow conditions. The role of: a) platelet membrane glycoproteins (GPS) or subunits; b) plasma adhesive proteins such as von Willebrand factor (VWF) and fibronectin (Fn); and c) structural proteins of the SE such as laminin (Lm). Specific antibodies or purified proteins were added to the perfusates. GPS. Monoclonal antibodies (MoAb) directed against distinct epitopes of the GPIIb-IIIa affected in different manner the deposition of platelets. MoAb EDU3 decreased (p less than 0.01) the surface of the vessel covered by platelets (% CS) and increased the presence of platelets in contact (% C) with the SE. MoAb C17 did not modify the % CS but altered the morphological characteristics of the aggregates. A monoclonal antibody against GPIIb, decreased the % CS (p less than 0.01) without influencing % C; VWF. A linear progression of the % CS was observed for VWF levels ranging from 0.1 to 0.6 U/mL. A plateau was reached for concentrations of vWF above 0.6 U/mL; Fn. Perfusions in which blood was reconstituted with Fn-depleted plasma showed the cooperation of this protein facilitating Plt-Plt interaction. No statistical differences were observed in the % CS when ECM were incubated with a MoAb against Fn (3E3); Lm. The % CS decreased statistically (p less than 0.01) when SE or ECM were incubated with an antibody to Lm. These results show the critical role of vascular, plasmatic and cellular components in the maintenance of and adequate platelet function.

Animals↗
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↗