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Biomedical subjects

D Riccardi

Publications and source records attributed to D Riccardi.

41 records · Page 3Linked to original sources
PubMed1989

Evaluation of platelet concentrates prepared from buffy coats and stored in a glucose-free crystalloid medium.

Comparison was made between platelet concentrates prepared from pools of buffy coats removed from standard blood donations and stored in a glucose-free, commercially available crystalloid solution (BC-PCs) and standard platelet concentrates prepared from platelet-rich plasma (PRP-PCs). Platelet yield in BC-PCs and PRP-PCs was 59 and 75 percent of donated platelets, respectively. The number of total white cells in 1 BC-PC unit, prepared from a pool of 7 buffy coats, was 21 x 10(6), i.e., 50 times lower than that of 7 units of PRP-PCs. The in vitro values of adequate platelet quality were maintained for 10 days in BC-PCs stored in 1000-mL polyolefin bags. Prolonged bleeding times were reduced or corrected in three of three thrombocytopenic leukemic patients evaluated before and after transfusion of stored BC-PCs. Pretransfusion and 1- and 24-hour posttransfusion median platelet counts in 57 leukemic recipients during 4 months of routine transfusion of BC-PCs (n = 93) were 14, 35, and 27 x 10(9) per L, while those of PRP-PCs (n = 246) were 13, 37, and 31 x 10(9) per L, respectively. No reactions to BC-PCs were reported, but a 1.3 percent rate of reaction to PRP-PC transfusions was reported. This study indicates that BC-PCs are a good alternative to PRP-PCs for platelet support of thrombocytopenic patients.

Adult↗
PubMedDate not supplied

The many roles of the calcium-sensing receptor in health and disease.

The physiological relevance of calcium in many vital processes requires that its concentration in extracellular fluids be kept within a narrow range. The near-constancy of this parameter emphasizes the remarkable sensitivity of cells sensing changes in extracellular calcium concentration to minimal fluctuations (< 2%) and the level of sophistication of the homeostatic system (1). The identification of a cell surface, Ca2+ (polyvalent cation)-sensing receptor (CaR), has shed considerable light on the molecular aspects of hypercalcemia on cell function (2). Activation of the receptor by calcium triggers an intracellular cascade of second messengers producing a variety of biological effects, many of which have yet to be understood. This suggests, for the first time, that Ca2+ can exert its effects in a hormone-like fashion without crossing the plasma membrane. The demonstration that inherited genetic disorders of Ca2+ homeostasis are associated with mutations that reduce or enhance responsiveness of the receptor to extracellular Ca2+ concentration clearly proposes CaR as the main regulator of divalent mineral ion excretion (3). This hypothesis is confirmed by the assessment of the presence of the receptor in all regions involved in Ca2+ homeostasis (e.g., parathyroid glands, kidney, calcitonin-secreting C cells, bone-derived cell lines, and intestine) (1,4-8). Recently, the receptor has also been found in regions not normally involved in mineral ion metabolism, such as the brain, eye, stomach, and pancreas (9-13). This clearly indicates a much broader relevance of CaR in the maintenance of local ionic homeostasis and, possibly, in the involvement in vital processes such as the regulation of cell fate.

Animals↗
PubMedDate not supplied

Quality assessment of transfusion practice in elective surgery.

A program of quality assurance (QA) was adopted to improve blood transfusion practice in elective surgery at a large urban hospital. For this purpose, a cooperative multidisciplinary group was formed, key indicators were identified, and an organization was set up. Data collected by this organization in the 1-year period needed for implementation of the program indicated that blood misuse was common practice. In fact, overrequest, overtransfusion, excessive reconstitution of whole blood (i.e., concurrent transfusion of red cells and fresh-frozen plasma), and underuse of predeposit were found in all ten surgical departments of the hospital. In a pilot study, data were collected from one surgical department during and after the implementation phase of the QA program; comparison of these data showed a postimplementation reduction of about two thirds in overtransfusion, whereas overrequest, reconstitution of whole blood, and predeposit rates remained unchanged. These results prompted continuation of the program in order to reach a definitive evaluation of its effectiveness.

Blood Transfusion↗
PubMedDate not supplied

Cell surface, Ca2+(cation)-sensing receptor(s): one or many?

In mammals Ca2+ concentration in the extracellular fluids ([Ca2+]o) is essential for a number of vital processes varying from bone mineralization to blood coagulation, regulation of enzymatic processes, modulation of permeability and excitability of plasma membranes. For this reason [Ca2+]o is under strict control of a complex homeostatic system that includes parathyroid glands, kidneys, bones and intestine. The extracellular Ca(2+)-sensing receptor (CaR) is an essential component of this system, regulating parathyroid hormone secretion, calcium (and magnesium) excretion by the kidney, bone remodeling and Ca2+ reabsorption by the gastrointestinal tract. Structurally, the CaR is a novel member of a growing G protein-coupled receptor superfamily, which includes metabotropic glutamate receptors (mGluRs) [1], [gamma]-aminoisobutyric acid (GABA-B) receptors [2] and vomeronasal organ receptors [3]. Initially identified from bovine parathyroid glands [4], within the 5 years following its identification CaR presence has rapidly been identified as extending to organs where the link with mineral ion metabolism has not been elucidated (i.e. brain, stomach, eye, skin and many other epithelial cells) (see [5] for review). The role of the receptor in these regions is largely unknown, but it appears to be somewhat related to phenomena such as chemotaxis, cell proliferation and programmed cell death. This review will describe the discovery of a novel class of ion-sensing receptor(s), receptor-effector coupling and the roles of the CaR inside and outside the Ca2+o homeostatic system.

Animals↗