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Biomedical subjects

C R Valeri

Publications and source records attributed to C R Valeri.

At least 217 records · Page 12Linked to original sources
PubMed1984

Antiinflammatory agents inhibit microvascular permeability induced by leukotrienes and by stimulated human neutrophils.

One pathologic change common to the inflammatory process is loss of microvessel membrane integrity which results in edema. Polymorphonuclear leukocytes (PMN) are primary contributors to the development of edema because they cause tissue injury which alters vascular permeability and hemodynamics. The aim of this study was to assess the influence of arachidonic acid metabolites generated by activation of human PMN on the in vivo microvascular preparation of the hamster cheek pouch. Fluorescein-labeled dextran MW: 150,000 was used to assess microvascular permeability. Human PMN were activated with arachidonic acid (AA) and the calcium ionophore A23187, and the supernatant retained for testing. Topical application of the PMN supernatant, purified LTD4 or LTB4 resulted in marked extravasation of macromolecules from post-capillary venules of control hamsters. The extravasation was reduced when hamsters were pretreated with indomethacin (5 mg/kg), imidazole (25 mg/kg), ketoconazole (10 mg/kg), 13-azaprostanoic acid (30 mg/kg), FPL 55712 (1 mg/kg) and dimethylthiourea (500 mg/kg). The interpretation of the results suggests that the increased vascular permeability induced by PMN secretions may be mediated in part by the thromboxane pathway.

Animals↗
PubMed1984

The production of granulocyte-monocyte colony-stimulating activity by isolated human T lymphocyte subpopulations.

Isolated human T lymphocyte subpopulations were obtained by fluorescence-activated cell sorting using the murine monoclonal antibodies, OKT4 and OKT8. The capabilities of the isolated lymphocytes to produce granulocyte-monocyte colony-stimulating activity (CSA) in response to mitogen challenge were assessed by in vitro assays employing light density nonadherent bone marrow cells. Essentially, no CSA production was noted by any isolated T lymphocyte population [OKT4 positive (+) or OKT8 positive (+)] cultured alone or following the addition of 10(4) autologous monocytes/ml. When phytohemagglutinin (PHA) alone was added, OKT4+ lymphocytes elaborated small amounts of CSA. With the addition of concanavalin A (Con-A) alone, both OKT4+ and OKT8+ cells were able to produce modest amounts of CSA. Significantly enhanced CSA production was observed when either OKT4+ or OKT8+ lymphocytes were coincubated with autologous monocytes in the presence of mitogen. We conclude that highly purified T lymphocyte subpopulations, free of monocytes as assessed by nonspecific esterase staining, can elaborate small amounts of CSA in response to PHA or Con-A challenge. A synergistic augmentation of CSA production was noted with coincubation of sorted lymphocytes and autologous monocytes in the presence of mitogen. Finally, our results suggest that the ability of T lymphocytes to make CSA is not exclusively limited to either the OKT4+ or OKT8+ defined subsets.

Antibodies, Monoclonal↗
PubMed1984

Platelet size and age determine platelet function independently.

This study was undertaken to examine the interaction of platelet size and age in determining in vitro platelet function. Baboon megakaryocytes were labeled in vivo by the injection of 75Se-methionine. Blood was collected when the label was predominantly associated with younger platelets (day 2) and with older platelets (day 9). Size-dependent platelet subpopulations were prepared on both days by counterflow centrifugation. The reactivity of each platelet subpopulation was determined on both days by measuring thrombin-induced aggregation. Platelets were fixed after partial aggregation had occurred by the addition of EDTA/formalin. After removal of the aggregated platelets by differential centrifugation, the supernatant medium was assayed for remaining platelets and 75Se radioactivity. Comparing day 2 and day 9, no significant difference was seen in the rate of aggregation of a given subpopulation. However, aggregation was more rapid in the larger platelet fractions than in the smaller ones on both days. A greater percentage of the 75Se radioactivity appeared in the platelet aggregates on day 2 than on day 9. This effect was independent of platelet size, as it occurred to a similar extent in the unfractionated platelets and in each of the size-dependent platelet subpopulations. The data indicate that young platelets are more active than older platelets. This study demonstrates that size and age are both determinants of platelet function, but by independent mechanisms.

Animals↗
PubMed1983

Measurement of the distribution of indium-111 on human plasma proteins using immunoprecipitation.

The distribution of radioactivity on plasma proteins labeled by addition of [111In]oxine to citrated plasma was investigated. Analyses of plasma proteins separated on Sephadex G-200 columns showed that 23-36% of the 111In was associated with proteins with molecular weight greater than 200,000 daltons and the remaining 111In was associated with proteins with molecular weight less than 100,000 daltons, presumably transferrin. Affinity chromatography experiments showed that less than 2% of the radioactivity was associated with albumin. Further identification of the labeled proteins and quantitation of associated radioactivity was performed by precipitating specific proteins with antibodies. These studies showed that the 111In was distributed on transferrin (54-76%), fibrinogen (11-24%), IgM (8-20%), C3 (10-21%), and haptoglobin (3-8%). 111In associated with fibrinogen, IgM, and haptoglobin was over-estimated in some experiments due to binding of 111In-labeled C3 to the antigen-antibody precipitates.

Blood Proteins↗
PubMed1983

Alteration of the electrophoretic mobility of human peripheral blood mononuclear cells following treatment with dimethyl sulfoxide.

Studies have been conducted to determine the effects of DMSO and freezing on the electrophoretic distribution of peripheral blood mononuclear cells. Sodium [51Cr]chromate was used to label the cells, and the distributions of cell number and cell-associated radioactivity were determined. Cells treated with DMSO had a narrower distribution of electrophoretic mobilities when compared with those not treated. DMSO-treated cells also demonstrated a more homogeneous distribution of radioactivity relative to the cell distribution than did the nontreated cells. The freezing of DMSO-treated cells did not result in any additional alteration of electrophoretic pattern compared to DMSO treatment alone. Analysis by linear categorization techniques indicated that the DMSO-treated and nontreated cells were completely distinguished by their electrophoretic behavior.

Blood Preservation↗
PubMed1983

The role of anticoagulation in the measurement of platelet volumes.

The effect of anticoagulation on platelet size stability was studied using blood collected in seven different anticoagulants and stored at room temperature for up to eight hours. The mean platelet volume (MPV) value was most stable in blood collected in 15% ACD and ACD/Na2EDTA. In blood collected in Na2EDTA, K3EDTA, or 11.9% ACD, there was an increase in MPV in the first two hours, after which the MPVs remained stable up to eight hours. Sodium citrate and heparin proved unreliable for the measurement of platelet volume. Platelet counts were stable (less than 5% variation) in all anticoagulants except heparin, which had 16% variation for the eight hours of study. Simultaneously, RBC counts and mean corpuscular volume (MCV) measurements were stable in all seven anticoagulants, with sodium citrate producing the most variation. A negative correlation was observed between MCV and pH of the anticoagulated blood. WBC counts showed less than 3% variation in all anticoagulants except sodium citrate and heparin. Separate experiments demonstrated that electrolyte composition, pH, tonicity, and method of calcium chelation all influenced the stability of the MPV. Of the anticoagulants studied, ACD/Na2 EDTA appeared to provide the best conditions of anticoagulation for both routine clinical and research laboratory measurement of the MPV. It inhibited platelet activation but left the platelets in their normal discoid shape. Platelets could be removed from the anticoagulant and studied in functional assays for up to eight hours after blood drawing. Both platelet counts and MPVs remained stable in blood collected in ACD/Na2 EDTA anticoagulant for up to eight hours at room temperature. In 52 volunteers studied, an inverse correlation (r = -0.72, P less than 0.001) was observed between platelet count and MPV, suggesting that the circulating platelet mass may be a more important indicator of platelet homeostasis than either the platelet count or the mean platelet volume alone.

Adult↗
PubMed1983

Arachidonic acid metabolism by platelets of differing size.

The relationship between mean platelet volume (MPV) and platelet arachidonic acid metabolism was examined by studying the ability of human platelets of different size to incorporate and metabolize tritiated arachidonic acid ([3H]AA). Platelet phospholipids were labelled with [3H]AA and the platelets were then fractionated into size-dependent subpopulations by counterflow centrifugation. The incorporation of [3H]AA increased through the fractions proportional to the MPV. After thrombin stimulation the per cent of total 3H-radioactivity released from the platelets decreased as the MPV increased. However, fractionation of the released 3H-radioactivity by HPLC (high performance liquid chromatography) demonstrated that MPV had no significant influence on the per cent of total platelet 3H-radioactivity released as cyclooxygenase products or as HETE (12-hydroxyeicosatetraenoic acid) but that the release of unmetabolized [3H]AA decreased as MPV increased. In separate experiments using unlabelled platelets the absolute release of thromboxane B2 (TXB2) after collagen- and thrombin-induced aggregation was measured by radioimmunoassay and was found to increase in proportion to the MPV. These results demonstrate that the release of arachidonic acid metabolites is qualitatively similar in platelets of different size. However, the absolute ability of platelets to incorporate arachidonic acid, convert it to active metabolites and release them is proportional to their volume. The ability of platelets to release unmetabolized arachidonic acid varies inversely with their MPV.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1983

An integrated liquid-frozen blood banking system.

Frozen red cells have been field-tested at the Mobile Fleet Hospital deployed at 29 Palms, Calif., and at Bridgeport, Calif., and at the PACOM Blood Program Office, Okinawa, Japan, to evaluate the feasibility of using these products to support the US Navy and Marines in combat areas. We studied both nonrejuvenated and rejuvenated cryopreserved red cell concentrates. Red cells stored at 4 degrees C in CPD or CPDA-1 for 3-6 days (nonrejuvenated), and red cells stored at 4 degrees C in CPD for 22-26 days or in CPDA-1 for 36-38 days before biochemical modification (rejuvenated), were frozen with 40% w/v glycerol at -80 degrees C. A multiple-bag collection system with a 600 or 800 ml primary bag was used for blood collection, and the primary bag was used for processing from preparation of the red cell concentrate through prewash dilution. The thawed red cells were washed with 1.5 liters of a sodium chloride-glucose-phosphate solution. As part of this feasibility study, frozen red cells were shipped by air in dry ice (-79 degrees C), and previously frozen washed red cells were shipped in wet ice (4 degrees C). In vitro red cell recovery values were at least 90%. After postwash storage at 4 degrees C for as long as 3 days, the red cells had 24-hour posttransfusion survivals of at least 70%, normal or slightly impaired oxygen transport function, and minimal hemolysis.

Blood Banks↗
PubMed1983

Thromboxane mediation of cardiovascular dysfunction following aspiration.

Acid aspiration leads to an inflammatory response characterized by the activation and pulmonary entrapment of platelets and while blood cells (WBCs. We speculate that thromboxane (Tx) produced by these activated cells alters lung permeability and diminishes cardiac performance. The lungs of dogs were aspirated with 0.1N HCl (3 ml/Kg). Within 30 minutes in six untreated controls, cardiac index (CI) decreased from 121 to 104 ml/min . kg (P less than ).05), mean arterial pressure decreased from 142 to 120 mm Hg (P less than 0.05), Pao2 decreased from 91 to 73 mm Hg (P less than 0.05), and TxB2 levels increased from 70 to 130 pg/ml (P less than 0.05). Pulmonary WBC sequestration occurred after 2 hours, while at 21/2 hours edema fluid was noted in the endotracheal tube. Six dogs were treated with infusion of the imidazole derivative ketoconazole 1 hour after aspiration (2.5 mg/kg bolus followed by 10 mg/kg . hr for 2 hours). After 30 to 60 minutes of treatment, CI rose from 106 to 143 ml/min . kg (P less than 0.05), TxB2 decreased from 130 to 70 pg/ml (P less than 0.05). At 21/2 hours, plasma from treated animals used to incubate a papillary muscle led to developed tension 8% higher than that in controls (P less than 0.05). Sequestration of WBC was not observed. After 4 hours, 24 ml endotracheal edema fluid was collected in contrast to 127 ml in controls (P less than 0.05). A hamster cheek pouch used for bioassay of microvascular permeability yielded 78 leakage sites/cm2 with control edema fluid and 26/cm2 with fluid from treated animals (P less than 0.05). The importance of WBC Tx synthesis in the induction of permeability was tested by stimulation of isolated WBCs with ionophore in the presence or absence of ketoconazole (0.4 Microgram/ml). Ketoconazole reduced the number of leakage sites in the hamster cheek pouch from 196/cm2 noted in controls to 28/cm2 (P less than 0.05). These data support our hypothesis that Tx directly or indirectly lead to cardiac depression and WBC-mediated permeability.

Animals↗
PubMed1983

Ischemia of the limb stimulates thromboxane production and myocardial depression.

Thromboxane A2 is thought to be an important mediator of cardiopulmonary dysfunction, hence stimuli that effect synthesis of this prostanoid are of major interest. In this study, the thesis that ischemia of the limb is a significant stimulus to thromboxane A2 synthesis and the generation of a circulating negative inotrope is tested. Twelve healthy volunteers, taking no medications and ranging in age from 21 to 29 years, underwent inflation of an arm cuff to either 70 or 220 millimeters of mercury for ten minutes. Immediately after deflation of the cuff from 220 millimeters of mercury, the stable degradation product of thromboxane A2, thromboxane B2, rose from a base line plasma level of 34 +/- 6 picograms per milliliter (mean +/- SEM) to 70 +/- 18 picograms per milliliter. In contrast, deflation from a cuff pressure of 70 millimeters of mercury resulted in a lower thromboxane B2 level of 26 +/- 9 picograms per milliliter (p less than 0.05). Plasma obtained before and after inflation of the cuff to 220 millimeters of mercury was used to bathe a rat papillary muscle. Developed tension fell from a base line of 2.80 +/- 0.19 to 2.44 +/- 0.17 grams (p less than 0.01). There was no significant change in developed tension induced by plasma harvested after the cuff was inflated to 70 millimeters of mercury. The base line plasma level of 6-keto-prostaglandin F1 alpha, the hydrolysis product of prostacyclin, was 46 picograms per milliliter; the plasma serotonin, 51 nanograms per milliliter; the platelet serotonin, 1.02 micrograms per 10(9) platelets; platelet count, 220,000 per cubic millimeter, and white blood count, 6,094 per cubic millimeter. These values did not change significantly with cuff inflation to either 220 or 70 millimeters of mercury. The results show that ischemia of the limb leads to thromboxane A2 production. Possible adverse cardiac effects related to this event are suggested by the bioassay demonstrating that circulating plasma with high levels of thromboxane B2 is associated with the depression of tension of an isolated rat papillary muscle.

Adult↗
PubMed1983

Horse red blood cells frozen with 20% (w/v) glycerol and stored at -150 C for five years.

When equine RBC were frozen with 20% (w/v) glycerol and stored at -150 C for as long as 5 years, there were no adverse effects on freeze-thaw or freeze-thaw-wash recovery or oxygen transport function. The manner in which the glycerol was added to, and removed from, the equine RBC was shown to be an important consideration in ensuring optimal freeze-thaw-wash recovery values.

Animals↗
PubMed1983

Platelet size as a determinant of platelet function.

The relationship between MPV and platelet function was studied in human platelet subpopulations separated on the basis of size and counterflow centrifugation. The original platelet population and five size-dependent platelet fractions were suspended in buffer or autologous PPP at a platelet count of 2 x 10(8)/ml. Collagen (10 micrograms/ml)-induced aggregation showed a significant negative correlation between MPV and onset of aggregation and positive correlations between the MPV and the rate of extent of aggregation. Thrombin stimulation (1 U/ml) demonstrated similar relationships between MPV and the rate of extent of aggregation. In contrast, ristocetin-induced platelet agglutination occurred at a similar rate and extent in all fractions. To quantitate further the differential response of the platelets, we measured the content and release of ATP and beta-TG. There was a significant correlation between MPV and both ATP and beta-TG content, and a progressive increase in the absolute release of ATP and beta-TG was associated with the increase in MPV through the fractions after stimulation. However, the percent release of total ATP and beta-TG was similar in all fractions. Our data indicate that the intrinsic function of platelets of different sizes is similar but that the absolute ability of platelets to affect their environment, as measured by aggregation and total release of granular content, correlates with their size.

Adenosine Triphosphate↗