Biomedical subjects

P Rustagi

Publications and source records attributed to P Rustagi.

6 recordsLinked to original sources

PubMed1998

Increased platelet activation and fibrinogen in Asian Indians. Potential implications for coronary risk.

AIMS: To determine whether Asian Indians (Indians), a group known to have high rates of coronary heart disease, have increased platelet activation and fibrinogen levels relative to white Americans of European origin (whites). METHODS AND RESULTS: Forty healthy, non-smoking Indians, aged 25-45, were matched with 40 healthy whites for age (within 3 years) and gender. Platelet activation was tested in blood exiting a bleeding time wound at 1 and 2 min post-incision (wound-induced activation), as well as in venous blood stimulated in vitro with collagen, using whole blood flow cytometry. Other risk factors, including fibrinogen levels, family history of diabetes or coronary heart disease, fasting insulin and lipid levels, and Lp(a) were also assessed. Fibrinogen levels were higher among Indians than whites, even after adjustment for gender or family history of coronary heart disease (P < 0.05). Indians had higher levels of wound-induced glycoprotein IIb/IIIa binding and platelet secretion (P-selectin expression) than whites, with the greatest differences found when comparing the upper quintile of activation for each group (Ps < 0.05). Indians with a family history of coronary heart disease (n = 15) had higher levels of platelet secretion (wound-induced and in vitro) than Indians without a family history (Ps < 0.05), while the relationship was reversed among whites. Platelet activation measures were not consistently related to other coronary risk factors, while fibrinogen was related to triglyceride and insulin levels among Indians. CONCLUSION: Indians have elevated fibrinogen and platelet activation levels relative to whites. These factors may contribute to the increased coronary risk observed in Indians.

Adult↗

PubMed1996

Biological activity of 26-succinylbryostatin 1.

Bryostatin 1, a macrocyclic lactone, has undergone phase I trials as an anticancer agent. Because of the lipid solubility of this compound it must be delivered either in ethanol or in a PET formulation. During the trial, these vehicles caused a large number of treatment-related side effects. We have synthesized the triethanolamine salt of 26-succinylbryostatin 1 and find that this compound is approx. 100-fold more water soluble than bryostatin 1. Because of the potential for clinical use, we have evaluated the biologic activity of this compound. We find that in a concentration-dependent manner 26-succinylbryostatin 1 is capable of activating protein kinase C (PKC) in vitro and displacing [3H]PDBu from PKC. However, at all concentrations tested the activity was less than the parent compound bryostatin 1. Addition of bryostatin 1 but not 26-succinylbryostatin 1 to U937 leukemic cells in culture stimulated a drop in cytosolic PKC, secondary to translocation of PKC to the membrane. Although 26-succinylbryostatin 1 did not stimulate a drop in the cytosolic levels of PKC, addition to U937 cells activated transcription from an AP-1 enhancer construct and c-Jun protein phosphorylation in a similar fashion to bryostatin 1 and differentiation of U937 cells. Unlike bryostatin 1, 26-succinylbryostatin 1 was unable to cause aggregation of human platelets. Although injection of bryostatin-1 into mice carrying B16 melanoma inhibits tumor growth, there was no significant inhibition of melanoma growth when identical doses of 26-succinylbryostatin 1 were injected. Therefore, 26-succinylbryostatin 1 shares some but not all of the pharmacologic properities of bryostatin 1. This compound can activate protein phosphorylation without lowering cytosolic levels of PKC.

Animals↗

PubMed1996

Multicentric evaluation of heparinase on aPTT, thrombin clotting time and a new PT reagent based on recombinant human tissue factor.

In a multicentric study the influence of heparinase (Hepzyme) was evaluated on activated partial thromboplastin time, thrombin clotting time and prothrombin time using the recombinant human tissue factor and synthetic phospholipid (phosphatidylcholine and phosphatidyl-serine reagent). Hepzyme itself does not have any influence on normal coagulation values of activated partial thromboplastin time (aPTT) and prothrombin time (PT) assays whereas thrombin clotting time was prolonged by 10% (n = 60). In patients treated with unfractionated heparin for recent deep vein thrombosis (n = 47), plasma levels of aPTT, PT and thrombin clotting time (TCT) returned to the normal range in 100%, 97% and 91% after treatment with heparinase, respectively. Plasma samples of patients on coumarin were spiked with 2IU heparin/ml (n = 40) and were treated with heparinase. aPTT returned to baseline levels in 97.5%, PT in 99% and TCT in 69% of the samples. Plasma samples of patients receiving both heparin and coumarin were treated with heparinase (n = 18). aPTT and TCT values were shortened substantially and displayed the prolongation due to the effect of oral anticoagulants. PT values in these patients were also shortened. Freezing of plasma samples after treatment with heparinase resulted in a prolongation of the coagulation times in 15% of PT, 7% of aPTT and not of TCT values. The results show that treatment of plasma samples with heparinase abolishes the effect of unfractionated and low molecular weight heparin in vitro and ex vivo in patients during simultaneous treatment with oral anticoagulants. The use of heparinase may be of significance in patients with concomitant treatment of heparin and oral anticoagulants.

Freezing↗

PubMed1996

Reversible prolonged skin bleeding time in acute gastrointestinal bleeding presumed due to NSAIDs.

The purpose of this research was to look for a possible mechanism whereby NSAIDs, and particularly ASA, might cause gastrointestinal bleeding. A total of 34 hospitalized GI bleeders and 29 age- and sex-matched controls were studied. Skin bleeding time (SBT) was measured within 6 h of coming to hospital and before any blood products were given. All patients and controls were questioned regarding current NSAID use. This history was supplemented by estimation of serum salicylate and of platelet cyclooxygenase activity to detect unreported current aspirin (ASA) use. Various aspects of platelet function were also tested by lumiaggregation in 28 controls and, after recovery, in 27 of the bleeders. Of 34 bleeders, 26 bled from the upper GI tract, (13 from peptic ulcer) and eight from the lower GI tract, 30 (88%) had a current intake of NSAIDs and of these 22 (73%) used ASA, some in combination with other NSAIDs, whereas 12 of 29 controls were using NSAID's, 11 of which were ASA. SBT in the bleeders was 9.0 +/- 1.02 min versus 4.8 +/- 0.42 min in the controls (p < 0.001). SBT measured 6.6 days later in 28 bleeders was 4.7 +/- 0.22 min (p < 0.0006), and of those tested after recovery all but one had fallen to 6.5 min or less. None had any residual constitutional platelet abnormalities as tested by lumiaggregation. By logistic regression, NSAID intake was strongly associated with prolonged SBT to > 6 min (odds ratio [OR], 16.7; p < 0.0002), whereas NSAID intake (OR 14.6; p < 0.0003) and SBT > 6 min (OR 1.8; p < 0.005) contributed to a bleeding outcome. Almost 90% of GI bleeders had recently consumed NSAIDs, mostly ASA, on an average 15 h before onset of bleeding. Although most of the nonbleeders who had used NSAIDs did not have a prolonged SBT, most of the bleeders who used NSAIDs had an abnormal elevation of SBT, suggesting a possible mechanism for GI bleeding. Retesting approximately 7 days after recovery from bleeding showed normalization of the SBT, indicating that the defect was transient and spontaneously reversible.

Acute Disease↗

PubMed1993

In vivo administration of the anticancer agent bryostatin 1 activates platelets and neutrophils and modulates protein kinase C activity.

Bryostatin 1 is a naturally occurring macrocyclic lactone which when applied to cells in culture activates protein kinase C (PKC). In vivo bryostatin 1 functions as an anticancer agent with activity against murine lymphomas, leukemias, and melanoma. Because all organs and tissues contain PKC, normal cells would also be a likely target for this agent. Here we demonstrate that in vivo administration of bryostatin 1 activates platelets over a dose range of 0.4 to 40 micrograms/kg with half-maximal activation occurring at 3 micrograms/kg and stimulation of neutrophils over a similar dose range. This in vivo activation of neutrophils is associated with a rapid decrease in measurable cytosolic PKC, a finding consistent with translocation of the enzyme to the membrane. In contrast, no statistically significant change in PKC location was found in liver, spleen, brain, or L10A B-cell lymphoma. However, in culture the L10A lymphoma did respond to bryostatin 1 with translocation of PKC. To evaluate whether the lack of effect of bryostatin 1 on PKC in organs was secondary to rapid degradation, we developed a bioassay to measure the levels of bryostatin 1 in the blood. To measure the presence of bryostatin 1, human neutrophils were incubated with plasma from mice given injections of different concentrations of bryostatin 1. Using this assay, bryostatin 1 at levels as low as 60 nM could be measured in the plasma. A time course with this bioassay demonstrated that less than 10% of the bryostatin 1 injected was detectable after 2.5 min. These results demonstrate that bryostatin 1 is capable of activating platelets and neutrophils and modulating PKC in vivo. The lack of effect of bryostatin 1 on specific organs may be secondary to the rapid clearance/degradation of this compound from the blood.

Animals↗

PubMed1989

Missed diagnosis?

Explore the source record for details and available documents.

Borderline Personality Disorder↗