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Biomedical subjects

C R Valeri

Publications and source records attributed to C R Valeri.

At least 235 records · Page 13Linked to original sources
PubMed1983

Platelet size does not correlate with platelet age.

The relationship between platelet size and in vivo aging was investigated in the baboon using size-dependent platelet subpopulations separated by counterflow centrifugation. The separation characteristics, size, lactate dehydrogenase (LDH) activity, and dense-body content of the baboon platelet subpopulations were similar to those previously observed in studies of human platelets. Three independent labeling techniques were used: (1) in vivo labeling with 75Se-methionine, (2) in vitro labeling with 51Cr, and (3) in vivo labeling with 14C-serotonin. Maximal incorporation of all three labels showed a close correlation between the mean platelet volume (MPV) of each fraction and the platelet radioactivity. The onset of incorporation and rate of accumulation of 75Se-methionine were comparable in all fractions when corrected for differences in volume, suggesting that platelet size heterogeneity was present from the time of release of the platelets from the bone marrow. Survival studies using 51Cr and 14C-serotonin showed no translocation of the label from one fraction to another in the circulation over time. In vivo survival values for the three radionuclides showed a slight but significant correlation between the lifespan and the MPV of the fractions. The data suggest that large platelets were not younger platelets, but rather platelets with a longer life-span. Platelet size heterogeneity is the result of production factors in the bone marrow and not maturation in the circulation.

Animals↗
PubMed1982

Platelet--arterial synthetic graft interaction and its modification.

We compared the in vivo platelet reactivity of two commonly used clinical grafts, Dacron and expanded polytetrafluoroethylene (PTFE), with that of a control autogenous artery graft and assessed whether platelet reactivity was modified by the platelet-antiaggregating agent prostacyclin (PGI2) (epoprostenol). Grafts were randomly placed into the carotid arteries of 21 baboons. Platelets labeled with indium 111 were infused within one hour after implantation graft for gamma camera scanning of platelet uptake. The accumulation of platelets on Dacron grafts began almost immediately after injection and reached a peak after one to two hours. The PTFE and control autogenous artery grafts accumulated comparable small amounts of platelets. Prostacyclin was then infused in a second series of baboons with Dacron grafts, at a rate of 150 to 200 ng/kg/min. It prevented the usual platelet uptake when administered concomitant with graft implantation and reduced previously established platelet activity.

Animals↗
PubMed1982

Size dependent platelet subpopulations: relationship of platelet volume to ultrastructure, enzymatic activity, and function.

A method for the separation of platelets on the basis of their size has been developed using counterflow centrifugation. Platelets were separated, free of plasma proteins and other cells, into seven subpopulations. The smallest-sized platelets, designated as Fraction 1, had a mean platelet volume (MPV) of 3.94 +/- 0.60 micrometer 3 (SD). Each successive fraction had a progressively larger MPV. The MPV for the largest-sized platelets, designated Fraction 7, was 8.19 +/- 0.64 micrometer 3. The MPV for the original platelets prior to fractionation was 6.57 +/- 0.61 micrometer 3. The mean density of Fraction 1 platelets was 1.067 +/- 0.002 g/cm3, while Fraction 7 had a mean density of 1.072 +/- 0.001 g/cm3. Transmission electron microscopy demonstrated that Fraction 1 had 4.3 +/- 0.9 dense bodies per platelet, and Fraction 7 had 12.6 +/- 2.4 dense bodies per platelet. Platelet LDH activity showed that the Fraction 1 platelets had 4.77 +/- 0.92 iu per 10(10) platelets; Fraction 7 platelets had 14.88 +/- 1.23 iu per 10(10) platelets. The LDH activity in the platelets before separation into subpopulations was 9.47 +/- 1.45 iu per 10(10) platelets. Platelet function was measured by ADP-induced aggregation, serotonin uptake, and thrombin-induced release. Progressively more rapid and more complete aggregation was observed as the platelet size increased over the seven fractions. Serotonin uptake was 4.2 times greater in the Fraction 7 platelets than in the Fraction 1 platelets. Quantitative release of serotonin following thrombin stimulation was significantly greater in the larger-sized platelets than in the smaller-sized platelets. The observed differences in platelet aggregation, dense body content, LDH activity, and serotonin uptake and release suggest that large platelets may be functionally more important than smaller platelets.

Adult↗
PubMed1982

A new approach to washing red blood cells frozen with a high concentration of glycerol in a special freezing container.

We report here on a new approach to washing red blood cells frozen with a high concentration of glycerol in a special freezing container. The wash solution consists of a 150-ml volume of 12% sodium chloride and 2 liters of 0.9% sodium chloride-0.2% glucose-25 mEq/l disodium phosphate. Both the Haemonetics Blood Processor 115 and the IBM Blood Processor 2991 have been used with this protocol, with similar results. The in vitro recovery of red blood cells frozen with 8.6M glycerol was 89%, and that of red blood cells frozen with 6.2M glycerol was 93%. The 24-hour posttransfusion survival values averaged 88% for eight units of outdated-rejuvenated previously frozen red blood cells washed by this protocol and stored at 4 degrees C for 3 days before autotransfusion.

Blood Preservation↗
PubMed1982

Cryopreservation of platelets isolated with the IBM 2997 blood cell separator: a rapid and simplified approach.

The equivalent of 5-7 units of platelets, isolated from a single donor with the IBM Blood Cell Processor 2997 using a dual stage separation chamber, was frozen with the cryoprotectant dimethylsulfoxide (DMSO). The DMSO-saline solution was added directly to the platelets, and the platelets were frozen in a polyvinyl chloride plastic bag by storage in a -80 degrees C mechanical freezer. Washing the thawed platelets with a phosphate-buffered sodium chloride-dextrose solution, pH of 5.0, removed about 95% of the DMSO. In vitro freeze-thaw-wash recovery was 80%, and in vivo 51Cr platelet recovery was 31%. Platelet dense body granules were well maintained after freezing, thawing, and washing. This is a safe and effective method of platelet cryopreservation which can be performed in less time than other currently used methods.

Adolescent↗
PubMed1982

Inhibition of permeability edema with imidazole.

Acute respiratory failure (ARF) with permeability edema and increased physiologic shunting (QS/QT) occurs after complement activation. Leukocytes aggregate, become entrapped in the lungs, and release vasotoxic agents. This study of 31 sheep infused with zymosan-activated plasma (ZAP) tests the hypothesis tha thromboxane (Tx) A2, a proaggregator and bronchoconstrictor, is an intermediate in complement-induced ARF. Group I animals (n = 11) were untreated controls. An imidazole infusion, 25 mg/kg . hr was started 1 hour before a ZAP infusion in group II (n = 10). Prostacyclin (PGi2) was given to group III sheep (n = 10) in a dose of 100 ng/kg . min 3- minutes before the ZAP infusion. Within 5 minutes ZAP led to a decrease in the leukocyte count to 2900/mm3 (P less than 0.001), a rise in plasma TxB2 concentration (the stable degradation product of TxA2) from 14 to 246 pg/ml (P less than 0.001), a rise in lymph TxB2 from 24 to 609 pg/ml (P less than 0.001), a rise in QS/QT from 13% to 31% (P less than 0.01), and a rise in mean pulmonary arterial pressure from 17 to 43 mm Hg. Both imidazole and PGI2 prevented the increase in TxB2 and QS/QT and limited the increases in MPAP to 25 and 30 mm Hg, respectively--values below those of untreated controls (P less than 0.05). Imidazole, but not PGI2, prevented the increase in lymph flow, which in controls increased from 2.8 +/- 8.5 ml/30 min (P less than 0.01), and lymph albumin clearance, which increased from 2.2 to 6.0 ml/30 min (P less than 0.01). The high lymph concentrations of TxA2 suggest a pulmonary site of production, and its bronchoconstrictive action may account for the increase in QS/QT. However, TxA2 is only partially responsible for the pulmonary hypertension and is apparently unrelated to changes in permeability. The protective action of infused imidazole against increased permeability appears to be independent of its inhibition of Tx synthetase.

Animals↗
PubMed1981

Sedimentation behavior of activated human granulocytes. Aggregation and volume effects.

Human peripheral blood granulocytes (PMNs) obtained from normal adults were studied by an analytical gravity sedimentation system. Exposure of PMNs to endotoxin-activated serum (EAS) in a Ficoll density gradient containing Hank's balanced salt solution with calcium and magnesium produced significantly different sedimentation patterns compared to those from granulocytes exposed to normal serum under the same conditions. Experiments were performed to determine whether changes in granulocyte density, volume, shape, or aggregation were responsible for the sedimentation pattern of granulocytes exposed to EAS. The altered gravity sedimentation behavior of endotoxin-activated granulocytes was abolished when calcium and magnesium were not present in the Ficoll density gradient. Granulocyte aggregation was inhibited by the absence of calcium and magnesium in the medium during granulocyte stimulation, whereas the changes in granulocyte shape and volume associated with granulocyte stimulation were not affected. The data indicate that the altered granulocyte sedimentation pattern in the presence of EAS and calcium and magnesium was produced by granulocyte aggregation and not by changes in granulocyte volume or shape.

Adult↗
PubMed1981

Cardiopulmonary function following transfusion of three red blood cell products in elective abdominal aortic aneurysmectomy.

In order to evaluate the importance of red cell O(2) affinity of transfused blood on cardiac performance and adverse effects of transfusion on lung function, a prospective double-blind protocol was used in 27 patients undergoing abdominal aortic aneurysmectomy. Three types of blood were administered: packed red cells (PC), washed red cells (WC) and high 2,3 DPG red cells (2,3 DPG). An average of 4.5 units of blood was used per patient. Transfusion of 2,3 DPG blood resulted in maintenance of in vivo P(50) during surgery and an increase to 31.2 torr after operation (p < 0.001). An intraoperative fall in in vivo P(50) to 23.2 +/- 2.0 torr was observed in patients who were transfused with PC (p < 0.001) and to 25.1 +/- 2.6 torr with WC (p < 0.005). A fall in body temperature averaging 2.2 C intraoperatively was noticed in all three groups. After operation, in vitro P(50) decreased in patients transfused with PC (p < 0.005) and WC (p < 0.005) while it remained unchanged in the high 2,3 DPG group. This was consistent with the decrease of red cell 2,3 DPG in the PC (p < 0.001) and WC groups (p < 0.01) and maintenance in the 2,3 DPG group. Left ventricular stroke work and volume loading Starling type myocardial performance curves were similar for the three groups. Microaggregates measured by Coulter counting and screen filtration pressure were the same for all three products in samples drawn on both sides of the 40 microm transfusion filter. There was no relationship of transfusion volumes or type of blood product to changes in lung function (physiologic shunting, dynamic compliance and pulmonary arterial pressure) in the three groups of patients. The false negative, beta, error of missing a true 25% difference was less than 10%. It is concluded that 2,3 DPG enriched red cells improved oxygen availability, but that a 4.5 unit transfusion of any of the three blood products did not influence lung function or myocardial performance following aneurysmectomy.

2,3-Diphosphoglycerate↗
PubMed1981

In vitro interactions of 51Cr in human red blood cells and hemolysates.

The intracellular distribution of radioactivity was studied in normal and sickle erythrocytes labeled with sodium 51Cr chromate. Both types of cells had a higher fraction of 51Cr bound to hemoglobin when labeled in the presence of ACD at a pH of 7.09 than when labeled in the presence of CPD at a pH of 5.96. Citrate at a pH of 5.96 or less entered the red blood cells and decreased the 51Cr binding hemoglobin. Binding of 51Cr to hemoglobin within the red cells was also reduced when the ATP and DPG levels in the red blood cells were elevated. Studies with hemoglobin solution showed that 51Cr binding to hemoglobin was influenced by 2,3-DPG, ATP and citrate.

Chlorides↗
PubMed1981

Studies on the in vivo elution of 51Cr from baboon red blood cells.

Four anticoagulant solutions were added to baboon red blood cells prior to labeling with 51Cr to determine how each would influence the distribution of 51Cr within the red blood cells, the loss of 51Cr from the red blood cells after transfusion, and the calculated red cell survival value. The 51Cr label was detected in the hemoglobin and in the low molecular weight compounds within the red blood cells. The elution of 51Cr from labeled baboon red blood cells following transfusion could not be explained by the distribution of 51Cr between hemoglobin and low molecular weight compounds within the red blood cells.

Animals↗
PubMed1981

Plateletpheresis experience with the Haemonetics Blood Processor 30, the IBM Blood Processor 2997, and the Fenwal CS-3000 Blood Processor.

Comparisons were made of the apheresis instruments Haemonetics Blood Processor 30, IBM Blood Processor 2997 and Fenwal CS-3000, for collection of platelets from normal donors. With each instrument the mean recovery was at least 4 x 10(11) platelets per procedure, and each instrument afforded a safe and reliable collection. The Haemonetics Blood Processor gave the lowest recovery of platelets per minute per procedure. The IBM Blood Processor 2997 required the longest time for set-up and priming and processed 1.5 liters more donor blood per collection than the other instruments. The Fenwal CS-3000, which is a computer-controlled instrument, was the least time consuming. The donor suffered a significantly greater drop in platelet count after collection with the IBM Blood Processor 2997 (31%) than after collection with the other instruments (19%), and we were unable to account for this observation.

Blood Platelets↗