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Biomedical subjects

D Riccardi

Publications and source records attributed to D Riccardi.

At least 37 records · Page 2Linked to original sources
PubMed1997

Relationship of the time of storage and transfusion reactions to platelet concentrates from buffy coats.

BACKGROUND: Transfusion reactions to platelet concentrates prepared from buffy coats (BC-PCs) were reviewed to determine the effect of some variables of BC-PC preparation and storage: time of BC storage before BC-PC preparation (1-2 days); time of BC-PC storage before transfusion (1-5 days); no white cell reduction versus laboratory and bedside BC-PC white cell reduction. STUDY DESIGN AND METHODS: A multiple linear logistic regression model was used by which the relative effect of one variable is expressed as the relative risk of transfusion reaction against a baseline level (1-day storage, no white cell reduction). RESULTS: During the 14 months of study, a total of 2707 BC-PC transfusions were given to 192 patients; 37 reactions (1.4%) were reported in 25 patients (13%). The transfusion reactions were febrile, nonhemolytic in 23 cases; allergic in 5; febrile and allergic in 2; and other in 7. The relative risk of transfusion reaction to BC-PCs prepared from BCs stored for 2 days was 1.98 times that to BC-PCs prepared from BCs stored for 1 day (p = 0.07). The relative risk of transfusion reaction of 5-day-old BC-PCs was 10.7 times that of 1-day-old BC-PCs (p = 0.001). The relative risk of transfusion reactions of BC-PCs white cell-reduced in the laboratory and at the bedside were 0.65 (p = 0.3) and 1.87 (p = 0.1) times, respectively, that of non-white cell-reduced BC-PCs. CONCLUSION: Time of storage seems to be an important variable associated with BC-PC transfusion reaction.

Blood Component Transfusion↗
PubMed1997

Respiratory mechanics in patients with tense cirrhotic ascites.

Lung volumes are decreased by tense ascites and increase after large volume paracentesis (LVP). The overall effect of ascites and LVP on the respiratory function is poorly understood. We studied eight cirrhotic patients with tense ascites before and after LVP. Inspiratory muscle force (maximal transdiaphragmatic pressure (Pdi,max), and the lowest pleural pressure (Pp1,min)) was assessed while the patients were seated. Rib cage and abdominal volume displacements, as well as pleural and gastric pressures were measured during quiet breathing while the patients were supine. Pdi,max and Ppl,min were normal and did not change after LVP (from 84.2+/-19.7 to 85.2+/-17.0 cmH2O and from 68.3+/-19.7 to 74+/-15.9 cmH2O, respectively). The abdominal contribution to the generation of tidal volume was greater than that of the rib cage (79 vs 21%), a pattern which did not change after LVP (73 and 27%). Before LVP, tidal swings both of pleural pressure (Ppl,sw) and transdiaphragmatic pressure (Pdi,sw) were large (15.3+/-4.3 and 18.5+/-3.9 cmH2O, respectively) and the load on inspiratory muscles was increased as a consequence of elevated dynamic elastance of the lung (El,dyn) (11.4+/-2.6 cmH2O x L(-1)) and ("intrinsic") positive end-expiratory pressure (PEEPi) (4.3+/-3.5 cmH2O). LVP reduced the load on the inspiratory muscles, as shown by the significant decrease in Ppl,sw (10.6+/-2.0 cmH2O), Pdi,sw (12.8+/-3.0 cmH2O), El,dyn (10.0+/-2.0 cmH2O x L(-1)) and PEEPi (1.1+/-1.3 cmH2O). The amount of fluid removed was closely related to changes in Ppl,sw and PEEPi. We conclude that the strength of the inspiratory muscles is normal or reduced in seated cirrhotic patients. In the supine position, tense ascites results in an increase in lung elastic load and development of positive end-expiratory pressure, with a consequent overload and increased activation of inspiratory muscles. Large volume paracentesis decreases overloading and activation, but does not change the strength of the inspiratory muscles.

Ascites↗
PubMed1997

Long course and prognostic factors of virus-induced cirrhosis of the liver.

OBJECTIVE: Chronic infection by hepatitis B virus (HBV) and hepatitis C virus (HCV) is now recognized as a major cause of liver cirrhosis. This study was aimed at evaluating the natural history of the disease in a large series of Italian patients with HBV- and HCV-related cirrhosis without portal hypertension at entry. METHODS: The clinical records of 405 patients (233 males, mean age 54 +/- 9 yr) with histologically proven cirrhosis (321 with HCV-related and 84 with HBV-related cirrhosis) and no clinical evidence of portal hypertension at entry were retrospectively examined to evaluate the occurrence of complications and the cumulative mortality rate during follow-up. RESULTS: Patients had a mean follow-up of 8 +/- 3 yr. The cumulative survival rate was 99.1% at 5 yr, 76.8% at 10 yr, and 49.4% at 15 yr. The age-adjusted death rate was 3.14 and 2.84 times higher than in the general Italian population in men and women, respectively. Only the bilirubin level was an independent indicator of survival. Esophageal varices, ascites, jaundice, hemorrhage, hepatic encephalopathy, and hepatocellular carcinoma significantly reduced the survival rate (major complications), whereas thrombocytopenia, diabetes, and cholelithiasis did not affect survival (minor complications). The incidence of hepatocellular carcinoma was similar in patients with either HBV- or HCV-related disease and was quite frequent, especially in males. CONCLUSIONS: This study demonstrates that the course of virus-induced liver cirrhosis is not influenced by the etiology of the disease and that the occurrence of complications significantly shortens life expectancy. The longer survival rate observed in this study is probably due to the fact that cirrhosis was here recognized by liver biopsy in the absence of clinical evidence of portal hypertension.

Bilirubin↗
PubMed1996

Specificity of coupling of muscarinic receptor isoforms to a novel chick inward-rectifying acetylcholine-sensitive K+ channel.

The G-protein-gated inward-rectifying K+ channel GIRK1 has been demonstrated in heart and brain. These tissues also both express the M2, M3, and M4, muscarinic acetylcholine receptors (mAChR) (Gadbut, A.P., and Galper, J.B. (1994),J. Biol. Chem. 269,25823-25829). Only the M2 mAChR has been demonstrated to couple to GIRK1 (Kubo, Y., Reuveny, E., Slesinger, P. A., Jan, Y. N., and Jan, L. Y. (1993) Nature 264, 802-806). In this study we determined the specificity of coupling of the M3 and M4 mAChR to a new GIRK1 cloned from a chick brain cDNA library. This clone codes for a 492-amino acid protein that is 93% identical to rat GIRK1 and is expressed in brain, atrium, and ventricle, but not skeletal muscle. In Xenopus laetis oocytes co-expression of GIRK1 with either the chick M2 or M4 mAChR gave carbamylcholine (10 microm)-stimulated K+ currents of 308 +/-26 nA and 298 +/-29 nA, respectively, which were both Ba2+- and pertussis toxin-sensitive. Activation of the M3 receptor produced 2382 +/-478 nA of current which was insensitive to Ba2+ and pertussis toxin, but was 85% inhabitable by the Cl channel blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid (10-20 microm) consistent with coupling to an endogenous Ca2+-activated Cl- channel via a phosphatidylinositol-dependent mechanism. Co-expression of the cardiac inward rectifier CIR with chick M2 or M4 mAChR and GIRK1 increased currents more than 10-fold, but had no effect on specificity of coupling. These data demonstrate a new function for the M4 mAChR and a high degree of specificity for coupling of each receptor subtype to GIRK1.

Acetylcholine↗
PubMed1996

Quality assurance of clinical transfusion practice by implementation of the privilege of blood prescription and computerized prospective audit of blood requests.

Guidelines, algorithms and recommendations have been issued in the attempt to ensure appropriateness of transfusion practice, but the results are less than satisfactory, mainly due to the difficulty to turn paper procedures into actual practice. In our hospital we have tried to overcome this difficulty through the implementation of a quality assurance programme which includes giving the privilege of nonurgent blood prescription to a limited number of physicians and a computerized prospective audit of blood requests. The latter is performed through verification of the compliance of blood requests, which are designed to include a patient's laboratory and clinical data, with hospital guidelines for the proper use of blood. In the 12 months since implementation of the computerized prospective audit the transfusion service has evaluated 7884 requests. Of these, 63.4% (n = 4998) were for red blood cells, 21.1% (n = 1664) for platelets and 15.5% (n = 1222) for fresh frozen plasma. The prospective audit showed that 96.8% and 98.1% of requests for red units and platelets were appropriate, respectively. Conversely, approximately 27% of plasma requests did not comply with guidelines, mainly because the evidence of coagulopathy was missing. However, inappropriateness of plasma requests for elective general surgery decreased from 39% at the onset of the programme to 14% in the last trimester considered. Moreover, the evaluation by retrospective audit of the proportion of patients transfused with both red blood cells and plasma in the perioperative period out of those transfused with red blood cells only, as an indicator of unwanted reconstitution of whole blood, showed that this proportion decreased from 47.6% (320/672) in the 12 months before implementation of computerized audit to 37.8% (244/646) in the following 12 months (difference = -9.8%, 95% confidence interval of the difference from -4.5% to -15.1%; P < 0.005 by chi 2 test). Our initial experience, together with the present system, shows that (1) the restriction of nonurgent blood prescription to a group of clinicians more educated in transfusion medicine than average clinicians practicing in a large multispecialty hospital is feasible; (2) prospective audit is a useful tool for assuring the quality of blood requesting.

Algorithms↗
PubMed1996

Impaired cardiovascular autonomic response to passive tilting in cirrhosis with ascites.

The autonomic regulation of cardiovascular function was evaluated in 15 cirrhotic patients with ascites and in 13 healthy subjects by the autoregressive power spectral analysis (PSA) of the intervals between adjacent R waves of the electrocardiogram (RR) interval and arterial pressure variability. Total power, low frequency (LF; index of the sympathetic activity of the heart and circulation), and high frequency (HF; index of vagal tone to the heart) components of the RR interval, systolic, and diastolic arterial pressure were evaluated in the supine position and during passive tilting, together with plasma norepinephrine levels. In the supine position, no significant differences in the PSA data were observed between the control subjects and cirrhotic patients, who had higher plasma norepinephrine levels. In healthy subjects, tilting was associated with an increase in the LF of the RR interval and arterial pressure and a decrease in the HF of the RR interval. In contrast, patients with cirrhosis showed a decrease of both LF and HF. Consequently, the LF/HF ratio significantly increased in healthy subjects, whereas it was unchanged in cirrhotic patients. The LF component of the diastolic pressure also decreased during tilting in cirrhotic patients. Plasma norepinephrine increased after tilting in both groups. These results indicate that the autonomic response to passive tilting is impaired in cirrhotic patients with ascites at both the cardiac and vascular levels, as a result of an altered sympatho-vagal balance, with reduced sympathetic predominance. These alterations occurred despite an appropriate response to the tilting of plasma norepinephrine, pointing to a receptorial or postreceptorial site of the autonomic impairment.

Adult↗
PubMed1996

Ontogeny of the extracellular calcium-sensing receptor in rat kidney.

We recently cloned extracellular Ca(2+)-sensing receptors (CaRs) from bovine parathyroid and rat kidney that play key roles in Ca2+ homeostasis. Inactivating mutations of the CaR in the inherited human disorder, familial hypocalciuric hypercalcemia, cause reduced responsiveness of the parathyroid to extracellular Ca2+ (Cao2+), as well as abnormally avid renal tubular reabsorption of both Ca2+ and Mg2+ in the distal tubule, suggesting an important role for the CaR in regulating parathyroid hormone (PTH) secretion and renal handling of divalent cations. High Cao2+ also inhibits vasopressinstimulated adenosine 3',5'-cyclic monophosphate accumulation in the medullary thick ascending limb (MTAL) and water reabsorption in the collecting duct (CD) and modulates various other aspects of renal function. The relevance of the CaR to these processes, however, is uncertain. Reduced responsiveness of vasopressin-and PTH-mediated actions on the kidney have been described in the newborn that could potentially reflect effects of the CaR on these aspects of renal function. To define further the role of the CaR in regulating renal function, including the above-mentioned changes during the perinatal period, therefore, we have studied its ontogeny in rat kidney. Northern and Western blot analyses, as well as immunohistochemistry with CaR-specific probes, demonstrate that there is little prenatal expression of the extracellular Ca(2+)-sensing receptor, except in large tubules and branching ureteric buds of developing nephrons. Postnatally, CaR mRNA and protein increase markedly during the 1st wk, related principally to expression of the receptor in the developing TAL and, to a lesser extent, in the CD. The level of expression of the receptor remains nearly constant after postnatal day 14. These results demonstrate that the perinatal increases in expression of CaR mRNA and protein parallel its tissue-specific renal expression. Furthermore, it is possible that some of the previously described changes in renal handling of divalent cations and water in the perinatal and immediate postnatal period are related, in part, to the increasing levels of expression of the CaR and resultant inhibitory effects on the actions of PTH and antidiuretic hormone on the developing nephron.

Aging↗
PubMed1996

Localization of the extracellular Ca(2+)-sensing receptor and PTH/PTHrP receptor in rat kidney.

Using a strategy based on homology to the bovine parathyroid Ca(2+)-sensing receptor previously identified by us (5), we have recently isolated an extracellular, G protein-coupled Ca2+/ polyvalent cation-sensing receptor, RaKCaR (22), from rat kidney. The localization and physiological role(s) of this receptor in the kidney are not well understood. In the present study, we assessed the distribution of mRNAs for RaKCaR and the parathyroid hormone/parathyroid hormone-related protein (PTH/PTHrP) receptor along the rat nephron by in situ hybridization and reverse transcriptase-polymerase chain reaction of microdissected nephron segments. Our results show that transcripts for both receptors coexpress at glomeruli, proximal convoluted tubule, proximal straight tubule, cortical thick ascending limb, distal convoluted tubule, and cortical collecting duct. In addition, RaKCaR (but not PTH/PTHrP receptor) transcripts were found in the medullary thick ascending limb and outer medullary and inner medullary collecting ducts. These findings raise the possibility of roles for RaKCaR not only in the regulation of divalent mineral reabsorption but also in water reabsorption and urinary concentration. Taken together, our results provide new insights in understanding the effects of hypercalcemia on hormone-stimulated salt and water transport.

Animals↗
PubMed1995

Cloning and functional expression of a rat kidney extracellular calcium/polyvalent cation-sensing receptor.

The maintenance of a stable extracellular concentration of ionized calcium depends on the integrated function of a number of specialized cells (e.g., parathyroid and certain kidney epithelial cells). We recently identified another G protein-coupled receptor (BoPCaRI) from bovine parathyroid that responds to changes in extracellular Ca2+ within the millimolar range and provides a key mechanism for regulating the secretion of parathyroid hormone. Using an homology-based strategy, we now report the isolation of a cDNA encoding an extracellular Ca2+/polyvalent cation-sensing receptor (RaKCaR) from rat kidney. The predicted RaKCaR protein shares 92% identity with BoPCaR1 receptor and features a seven membrane-spanning domain, characteristic of the G protein-coupled receptors, which is preceded by a large hydrophilic extracellular NH2 terminus believed to be involved in cation binding. RaKCaR cRNA-injected Xenopus oocytes responded to extracellular Ca2+, Mg2+, Gd3+, and neomycin with characteristic activation of inositol phospholipid-dependent, intracellular Ca(2+)-induced Cl- currents. In rat kidney, Northern analysis revealed RaKCaR transcripts of 4 and 7 kb, and in situ hybridization showed localization primarily in outer medulla and cortical medullary rays. Our results provide important insights into the molecular structure of an extracellular Ca2+/polyvalent cation-sensing receptor in rat kidney and provide another basis on which to understand the role of extracellular divalent cations in regulating kidney function in mineral metabolism.

Amino Acid Sequence↗
PubMed1995

Blunted natriuretic response to low-dose brain natriuretic peptide infusion in nonazotemic cirrhotic patients with ascites and avid sodium retention.

Patients with cirrhosis and ascites have high plasma levels of atrial (ANP) and brain (BNP) natriuretic peptides, two cardiac hormones released by the atria and ventricles, respectively. We evaluated renal hemodynamics, sodium excretion, and intrarenal sodium handling (lithium clearance method) in seven cirrhotic patients with ascites and avid sodium retention before, during, and after the infusion of synthetic human BNP, at the dose of 4 pmol/kg.min for 1 hour, which has been shown to increase renal plasma flow, glomerular filtration rate (GFR), and sodium excretion in healthy subjects without affecting systemic hemodynamics. Plasma BNP levels were 7.31 +/- 0.85 pmol/L in baseline conditions, and increased to 33.60 +/- 2.96 pmol/L at the end of the infusion (P < .01 vs. baseline). Urinary excretion of guanosine 3',5'-cyclic monophosphate (cGMP) also significantly increased during the infusion, indicating stimulation of natriuretic peptide receptors by BNP. BNP administration did not modify renal plasma flow, GFR, sodium excretion or tubular sodium reabsorption to any appreciable extent. Arterial pressure heart rate, plasma norepinephrine, and plasma renin activity (PRA) where also unchanged, whereas plasma aldosterone concentration showed a significant, 35% reduction at the end of the postinfusion period, ruling out the possibility that BNP-induced vasodilation might be responsible for failure of the peptide to induce a natriuretic response. Overactivity of antinatriuretic factors is probably the main determinant of the blunted natriuretic effect of BNP in these patients.

Adult↗
PubMed1994

Biosynthesis of platelet-activating factor and its 1O-acyl analogue by liver fat-storing cells.

BACKGROUND/AIMS: Platelet-activating factor (PAF) is an important mediator of proinflammatory cell-to-cell interactions with powerful vasoactive properties. We evaluated the biosynthesis of PAF by cultured human fat-storing cells (FSC), liver-specific pericytes involved in the inflammatory and fibrogenic process of liver tissue. METHODS: PAF synthesis was evaluated by measuring [3H]acetate incorporation under basal conditions and upon stimulation with A23187, thrombin, and lipopolysaccharide. Further analysis of PAF species synthesized by FSC was performed using gas chromatography/mass spectrometry. RESULTS: All stimuli induced a significant increase of basal PAF synthesis by FSC. Further analysis showed that > 50% of the newly synthesized PAF species was secreted whereas the remaining fraction was cell-associated. PAF species produced by FSC were able to induce aggregation of rabbit washed platelets with an effectiveness correspondent to 10(-9) mol/L authentic PAF. Gas chromatography/mass spectrometry analysis revealed that a large percentage (74%) of PAF-like lipids synthesized by FSC consisted of 1O-acyl PAF. Finally, stimulation of FSC with PAF caused an increase in cytosolic free calcium, thus suggesting a possible involvement of this pericyte in the well-known effects of PAF on portal pressure. CONCLUSIONS: These results expand the available knowledge concerning the role of PAF in conditions characterized by extensive activation and damage of the liver sinusoidal endothelium and decreased hepatic scavenger activity.

Acetates↗
PubMed1994

Ultrastructural, histochemical and electrophysiological study of calf gallbladder epithelium.

Calf (Bos taurus) gallbladder, contrary to that of most mammalian, does not concentrate bile. It is to be ascertained whether this phenomenon is the result of a lack of fluid absorption or a balance between the latter and fluid secretion. To this end we began a characterization of bovine gallbladder epithelium by means of electron microscopy, immunocytochemistry, enzymatic activity and electrophysiological measurements. We also partially characterized bile content. The ultrastructural examination showed that surface epithelial cells have the general structure that is observed in absorptive epithelia. Mucous secretory activity is also evident. Moreover, two distinct types of secreting cells line the glands in the lamina propria and contribute to the production of an abundant secretion. The cell surface shows a marked reactivity with the anti-alkaline phosphatase serum. Most of the activity of alkaline phosphatase and L-gamma-glutamyltransferase is found at the apical side of the epithelium. Electrophysiological parameters indicate that this is a low resistance epithelium. Therefore, coexistence of features typical of absorptive epithelia and the inability of concentrating bile suggest that, in this organ, fluid absorption and secretion are both present.

Alkaline Phosphatase↗
PubMed1993

Cloning and characterization of an extracellular Ca(2+)-sensing receptor from bovine parathyroid.

Maintenance of a stable internal environment within complex organisms requires specialized cells that sense changes in the extracellular concentration of specific ions (such as Ca2+). Although the molecular nature of such ion sensors is unknown, parathyroid cells possess a cell surface Ca(2+)-sensing mechanism that also recognizes trivalent and polyvalent cations (such as neomycin) and couples by changes in phosphoinositide turnover and cytosolic Ca2+ to regulation of parathyroid hormone secretion. The latter restores normocalcaemia by acting on kidney and bone. We now report the cloning of complementary DNA encoding an extracellular Ca(2+)-sensing receptor from bovine parathyroid with pharmacological and functional properties nearly identical to those of the native receptor. The novel approximately 120K receptor shares limited similarity with the metabotropic glutamate receptors and features a large extracellular domain, containing clusters of acidic amino-acid residues possibly involved in calcium binding, coupled to a seven-membrane-spanning domain like those in the G-protein-coupled receptor superfamily.

Amino Acid Sequence↗
PubMed1993

Platelet concentrates from buffy coats: improved conditions for preparation and evaluation in routine clinical use.

Since 1990, platelet concentrates prepared by soft centrifugation of buffy-coat pools diluted with a glucose-free, commercially available crystalloid solution (BC-PC) are the first choice product for all platelet recipients in our institution. Numerous in vitro and in vivo observations from our own and other laboratories indicate that BC-PC compare favorably to PC prepared from platelet-rich plasma (PRP). In the present in vitro study we evaluated traditional and bottom-and-top bags and modified centrifugation conditions with the aim of increasing in vitro platelet yield in BC-PC. This was 14-18% higher compared with our previous protocol when prolonged centrifugation and bottom-and-top bags were used. In addition, we evaluated post-transfusion platelet count increments in 42 unselected adult hematological patients routinely transfused with 703 1-5 day-old BC-PC pools. Transfusion data were managed with PLATELET, an MS-DOS compatible program which includes automated calculation of transfusion efficacy and periodic patient reports. Mean pre-, 1 h and 24 h post-transfusion platelet counts were 16, 38 and 28x10 9/L, respectively. Mean 1 h and 24 h post-transfusion platelet count increments, expressed as percentage of expected, were 40 and 24%, respectively. These data were similar to those obtained previously in 189 unselected hematological patients given 2432 PRP-PC transfusions (mean 1 h post-transfusion increment 46% of expected). The present in vitro study confirms that similar platelet yields can be obtained with the BC and PRP methods. In vivo findings show that also in routine conditions post-transfusion increments of PRP-PC and BC-PC are similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗