Search PubMed⌕ Search

Biomedical subjects

P Rebulla

Publications and source records attributed to P Rebulla.

At least 127 records · Page 7Linked to original sources
PubMed1979

Membrane abnormalities of pyruvate kinase deficient red cells.

Two experimental systems have been applied to the study of PK-deficient red cells in an attempt to reveal possible membrane abnormalities of these erythrocytes: (1) the glycoprotein self-digestion of intact erythrocytes during in vitro incubation at 37 degrees C; (2) the red cell sensitivity to the lytic action of mouse macrophages. PK-deficient erythrocytes display a more precocious than normal membrane glycoprotein self-digestion and are much more susceptible than normal to the cytotoxic activity of mouse macrophages. This latter effect is more pronounced in young than in old PK-deficient red cells. These observations indicate the existence of membrane abnormality in PK-deficient red cells other than those so far suspected.

Adenosine Triphosphate↗
PubMed1979

Concomitance of an active and an inactive mutant of red cell pyruvate kinase (PK).

A new mutant red cell PK associated with mild chronic haemolytic anaemia is described. The propositus, double heterozygous for a maternal gene coding for a structural abnormal enzyme and a paternal gene coding for a catalitically inactive enzyme, was suitable for an accurate functional characterization of the PK variant since his erythrocytes contained only one active mutant form of this enzyme. The active isoenzyme was characterized by low activity, decreased affinity for phosphoenolpyruvate, incomplete fructose-1,6-diphosphate activation, increased 'zero-time transition temperature', increased stability to guanidine-HCl and storage at +4 degrees C, increased guanosine-5'-diphosphate and cytidine-5'-diphosphate utilization, altered electrophoretic pattern with a single slow-moving component and abnormal isoelectric point. Affinity for ADP, ATP inhibition, optimum pH, molecular weight of the subunits, antigen concentration and immunological properties were in the normal range.

Adult↗
PubMed1978

A new mutant erythrocyte glucosephosphate isomerase (GPI) associated with GSH abnormality.

A case of congenital nonspherocytic haemolytic anaemia associated with a new abnormal glucosephosphate isomerase (GPI), GSH (reduced glutathione) deficiency, and instability and altered carbohydrate membrane composition is reported. The only functional abnormality of the mutant enzyme seems to be a marked instability to heat, urea, and guanidine-HCl. Family studies suggest that the propositus is doubly heterozygous for a maternal gene producing an inactive enzyme and a paternal gene responsible for a structural alteration causing marked lability of the coded enzyme. Experiments of incubation of normal GPI and the propositus's GPI with oxidizing and reducing agents seem to indicate that the abnormality resides in the SH groups of the mutant GPI.

Adolescent↗
PubMed1978

Hereditary pyruvate kinase deficiency: role of the abnormal enzyme in red cell pathophysiology.

Two new mutant Pks, electrophoretically identical but kinetically slightly different, are reported. These two clinically innocuous PK variants, encountered in two non-related subjects, have combined in their daughter to give a fully expressed haemolytic anaemia. The functional abnormalities of the daughter's PK (increased K0.5 PEP, abnormal response to FDP, increased urea and guanidine-HCl stability, abnormal isoelectrofocusing and electrophoretic patterns) were like those of the parents but more pronounced, except for thermostability that was normal in the proband although markedly decreased in both parents. The family examined demonstrates that there is no relationship between in vitro properties of the variant and the severity of haemolysis. The hypothesis is put forward that the cause of haemolysis in PK deficiency may be associated with another defect located in the red cell membrane.

Anemia, Hemolytic↗
PubMed1976

Effects of sulphydryl compounds on abnormal red cell pyruvate kinase.

The effect of some sulphydryl compounds on two new variants of red cell pyruvate kinase (ATP: pyruvate phosphotransferase, PK) is reported. In vitro a striking correction has been obtained of both the qualitative and, in one case, the quantitative defect of red cell PK. In vivo, a correction of the qualitative and quantitative abnormalities has been produced in both patients, with clinical improvement of one of them. These findings, together with the unexpected results in respect to the functional properties of PK found in the affected members of the two families studied, suggest that the PK abnormality is not the cause of the haemolytic anaemia, but an epiphenomenon of a primary unknown defect that apparently involves the red cell thiol groups.

Adenosine Triphosphate↗
PubMedDate not supplied

Number of random test cells for antibody detection.

The sensitivity of antibody screening carried out by reacting a serum with random test cells depends on the probability of a given antigen being present in the cell panel. This probability (p) is defined by the formula p = 1-(1-f)n where f is the antigen phenotype frequency and n the number of reacted random cells.

Antibodies↗
PubMedDate not supplied

The preparation of leukocyte-poor red cells for transfusion by a simple cost-effective technique.

A modification of the microaggregate filtration technique for the production of leukocyte-poor red cell concentrate is described. The modified technique, termed 'spin, cool, and filter', removed leukocytes more efficiently from relatively fresh blood than the original microaggregate filtration procedure. The residual leukocyte content of 4- to 9-day-old units processed by the modified procedure averaged less than 0.4 X 10(9) white cells per unit. The microaggregate filtration technique, supplemented by buffy-coat exclusion, removed more than 93 percent of the units' white cells. These red cell products were prepared easily and did not elicit febrile reactions in highly susceptible patients.

Blood Preservation↗
PubMedDate not supplied

Red cell alloantibodies in thalassemia major. Results of an Italian cooperative study.

Clinical and serological data on 1435 Italian thalassemia major patients were collected during a cooperative study involving 19 centers in 10 regions. The main findings were as follows: 18 percent of the patients were under 6 years of age, 63 percent between 6 and 15, and 19 percent over 15. Forty-one percent had undergone splenectomy. Sixty-two percent of the patients were maintained at pretransfusion hemoglobin levels higher than 10 g per dl, 36 percent between 8 and 10 g per dl, and 2 percent below 8 g per dl. Overall, 5.2 percent of the patients had clinically significant red cell alloantibodies (136 alloantibodies in 74 patients). One-half of the immunized patients had more than one and one-fourth had more than two alloantibodies. The specificities of the 136 alloantibodies were almost exclusively confined to the common antigens of the Rh, Kell, Kidd, and Duffy systems, in that decreasing order of frequency. The antibody screening procedure, using a low-ionic-strength solution antiglobulin test against a three-red-cell panel and the patient's own red cells (autocontrol) with a serum to cell ratio of 100 to 1 was shown to be an adequate technique for red cell antibody detection.

Adolescent↗
PubMedDate not supplied

The manual preparation of leukocyte-poor red cells for transfusion by a new filter.

Standard and buffy-coat-depleted red cell concentrates were filtered through a new cellulose acetate filter with a manual procedure. No residual leukocytes could be detected in 19 of the 21 filtered units. Extracellular hemoglobin after red cell filtration and concentration never exceeded 10 mg per unit. No transfusion reaction occurred in 10 recipients with potent lymphocytotoxic antibodies in their serum and histories of febrile transfusion reactions. This filter allows the preparation of leukocyte-poor red cell units with a safe, simple, and effective manual procedure.

Blood Transfusion↗
PubMedDate not supplied

Leukocyte depletion of red cell units at the bedside by transfusion through a new filter.

Standard packed red cell (PRC) units can be depleted of leukocytes and platelets if they are transfused through a blood administration set in which the usual 170-mu filter has been replaced by a leukocyte removal filter (Sepacell R-500). During a 6-month period, 1550 PRC units were transfused through this filter in 611 transfusions to 80 multitransfused patients with thalassemia who had had a patient reaction rate (PRR) of 63 percent and a transfusion reaction rate (TRR) of 13 percent when given standard PRC or buffy-coat-depleted PRC. When given filtered PRC, PRR and TRR became 3.7 percent and 0.5 percent, respectively. The effectiveness of the filter was also evaluated in vitro. By filtering 2 standard PRC units through the same filter, median values (and ranges) for red cell recovery and for residual leukocytes and platelets were 87 percent (83-92), 6.1 X 10(6) (0-100), and 2.7 X 10(9) (0.6-9.7), respectively. Although refinements are needed to improve standardization of the filter and to increase red cell recovery (which is low when 1 unit is filtered through one filter) and blood administration rate, the ability to provide leukocyte-free red cells prepared at the bedside for virtually all recipients appears to be a realistic goal.

Blood↗
PubMedDate not supplied

Inhibition of in vitro adherence of antibody-coated red cells to monocytes by the dialyzable leukocyte extract.

The red cell-monocyte assay (RMA), which has been used to evaluate the clinical significance of red cell (RBC) antibodies, was employed to test the effect of the dialyzable leukocyte extract (DLE) on in vitro adherence to monocytes of human RBCs coated with alloantibodies or autoantibodies. The total association index (TAI) of the RMA, expressing the number of RBCs adhering to or phagocytosed by 100 monocytes, indicated a potent inhibitory activity of DLE in the test system. TAI values of 100.4 +/- 20.1 (mean +/- SD) in the control sample, consisting of RBCs coated in vitro with anti-D, dropped to 4.0 +/- 2.1 when DLE was present in the assay medium at a concentration of 0.5 U per mL. Similar results were obtained with RBCs coated with IgG antibodies in vivo. The inhibition was dose dependent and was associated with a thermolabile component of DLE. This study establishes that DLE can modulate monocyte function by inhibiting the recognition of IgG sensitized red cells.

Cell Adhesion↗
PubMedDate not supplied

Use of IgM monoclonal reagents licensed for tube tests in column agglutination technology.

BACKGROUND: Red cell (RBC) phenotyping using column agglutination technology (CAT) is currently limited by the reagents formulated in the system. To overcome this limitation, it was investigated whether monoclonal IgM reagents licensed for use with tube tests produced valid results with CAT. STUDY DESIGN AND METHODS: Commercial CAT, does not contain antisera, was used to evaluate Procedures A (40 microL of reagent and 10 microL of 4% RBCs) and B (50 microL of reagent and 50 microL of 0.8% RBCs) with or without incubation at room temperature. In Study 1, reagents were tested to determine whether potentiators inhibit the passage of antigen-negative RBCs through the column. In Study 2, CAT sensitivity was measured by the use of potency titrations to define a procedure for each reagent that matched or exceeded that of the tube method. In Study 3, the specificity of each reagent was determined in parallel with the CAT and tube tests. Typing of 1644 samples was performed. RESULTS: Study 1: Free passage was obtained with all reagents. Study 2: Immediate-spin methods using CAT produced the same results as the tube method. Study 3: With 8048 comparisons made, discrepant results were found in 32 transfused patients and in 6 cord blood samples, mainly with Lewis reagents. With comparison of CAT and the standard tube method, complete agreement was obtained with Kell reagents, 99.9-percent agreement with Kidd reagents, and 98.9-percent and 99.4-percent agreement with Lewis reagents. CONCLUSION: Most examined reagents seem suitable for use with CAT.

Aged↗
PubMedDate not supplied

Transfusion reactions in thalassemia. A survey from the Cooleycare programme. The Cooleycare Cooperative Group.

A survey on transfusion reactions in thalassemia was carried out within the COOLEYCARE Programme, a cooperative enterprise aimed at improving quantity and quality of life in thalassemia through a program of quality assurance of treatment delivered to patients. Reactions were reported in 1,225 of 111,590 red cell transfusions (1.1%) given during 40 months (September 1985-December 1987) to 3,755 thalassemics in Italy and Greece. About 90% of red cell units were leukocyte-poor. Filtration was the most commonly used technique for leukocyte removal. Chills, fever, urticaria, headache and chest pain accounted for more than 80% of symptoms reported. Reactions were reported during transfusion in two thirds of cases. Although reactions were reported from 16% of patients, three quarters of reacting patients had no more than 2 reactions in 40 months.

Blood Group Incompatibility↗