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Biomedical subjects

R A Gruppo

Publications and source records attributed to R A Gruppo.

6 recordsLinked to original sources
PubMed1992

Induction of immune tolerance in patients with hemophilia A and inhibitors.

Infusions of factor VIII at 50-100 U/kg were administered "on demand" for bleeding episodes, or once weekly, in eight patients (aged 3-20 years) with hemophilia A and historically high titer inhibitors to factor VIII. Inhibitors were eliminated and immunologic tolerance to factor VIII occurred in five of the eight patients within 5-31 months. Four patients had minimal anamnestic responses upon starting factor VIII infusions. One patient, who continued on weekly factor VIII after appearance of the inhibitor, had a continued rise in titer for 10 weeks, followed by a gradual decrease and elimination of the inhibitor at 24 months. Three patients had marked anamnestic rises in the inhibitor levels (204-2150 BU) at the start of the factor VIII infusions, followed by a slow fall and eventual suppression of the inhibitor titers to less than 15 BU. The administration of IgG, cyclophosphamide, and prednisone was only partially successful at enhancing inhibitor suppression in two of the highest responding patients. This less intensive factor VIII infusion program appeared as effective, better tolerated, and less costly than other more intensive protocols utilizing daily factor VIII for inducing immune tolerance in hemophilia patients with inhibitors.

Adolescent↗
PubMed1991

Influence of plasma and red cell factors on the rheologic properties of oxygenated sickle blood during clinical steady state.

Yield stress is a sensitive index of blood fluidity at low shear stress. Using a method that measured the stress required to cause motion of a thin sedimenting layer of red cells, we found significant elevations of yield stress in patients with homozygous sickle cell anemia during clinical steady state. Mixing studies of sickle cells in normal plasma and buffered saline and of normal red cells in sickle plasma showed (1) that the increased yield stress of sickle blood was not due to differences between sickle and normal plasma factors and (2) that yield stress of sickle cells was not increased in the absence of plasma proteins. Multivariate regression analysis was performed to determine the dependence of sickle blood yield stress on several red cell and plasma factors. The yield stress measurements were normalized for differences in plasma fibrinogen concentration. Other factors studied included cell density, fetal hemoglobin concentration, alpha globin genotype, cell deformability as measured by high shear viscosity, and fibronectin and von Willebrand factor concentrations. Cell density was the primary determinant of yield stress. Measurements of yield stress on density fractionated sickle cells confirmed that the increased yield stress of sickle blood was due to the dense sickle erythrocyte. We conclude that the increased yield stress of sickle blood during clinical steady state was due to an abnormal interaction between the dense sickle cell membrane and plasma protein(s).

Adolescent↗
PubMed1989

Evaluation of the yield stress of normal blood as a function of fibrinogen concentration and hematocrit.

The yield stress is a sensitive index of blood fluidity at low shear. Seven healthy adults were studied at hematocrits varying between 40 and 80% and fibrinogen concentrations from 0.0 to 0.935 g/dl. Multivariable analysis was used to determine the functional dependence of yield stress on hematocrit and fibrinogen level. The major findings from this analysis include a decreasing effect of fibrinogen at high concentrations (saturation effect), a relative insensitivity of yield stress to fibrinogen at low concentration (threshold effect), and a strong interaction between the effects of hematocrit and fibrinogen concentration on yield stress. Our results give the normal range of yield stress for a given value of fibrinogen and hematocrit and can be used to predict the effect of reductions in hematocrit or fibrinogen on the yield stress of normal blood.

Adult↗
PubMed1988

Transient myeloproliferative disorder and acute nonlymphoblastic leukemia in Down syndrome.

Two infants with Down syndrome had transient myeloproliferative disorder (TMD) during the neonatal period and subsequently acute nonlymphoblastic leukemia (ANLL). Histochemically, the blast cells in TMD were indistinguishable from those in ANLL. Only the constitutional chromosome (trisomy 21) was found in TMD, whereas new cytogenetic abnormalities emerged in ANLL. A mixed growth pattern in stem cell cultures during TMD suggested the existence of an abnormal clone that might be responsible for the evolution into ANLL at a later date. Serial cytogenetic studies and culture studies of peripheral blood cells may help to understand the pathophysiology and risk of ANLL in patients with TMD.

Acute Disease↗
PubMed1977

Bone marrow cellularity determination: comparison of the biopsy, aspirate, and buffy coat.

Bone marrow biopsies (244) performed with a Jamshidi needle were evaluated in 53 children with leukemia or aplastic anemia. Adequate specimens were obtained in 85%. Results of cellularity estimated by biopsy were compared to the cellularity of the aspirate versus volumetric determination of the myeloid-erythroid layer (buffy coat). A wide discrepancy was noted between marrow cellularity confirmed by biopsy versus the aspirate or buffy coat. The greatest variance was seen in the hypercellular or normocellular marrows, as estimated by biopsy, in which 39% were misinterpreted as moderately or severely hypocellular by aspirate. Volumetric measurement of buffy coat was least acceptable for estimating cellularity. Thus the biopsy has proved to be an important and reliable indicator of bone marrow cellularity.

Anemia, Aplastic↗