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Biomedical subjects

G Gauvin

Publications and source records attributed to G Gauvin.

10 recordsLinked to original sources
PubMed1997

Validation of the heat treatment step used in the production of diaspirin crosslinked hemoglobin (DCLHb) for viral inactivation--effect of crosslinking.

Two experiments were performed to assess viral inactivation during the crosslinking and heat treatment steps of the DCLHb manufacturing process. Stroma free hemoglobin (SFHb) collected from a large scale manufacturing lot was tested in a 1:680 scaled down system in which the key parameters used in the manufacturing process were replicated. In the first study Porcine Parvovirus (PPV), a non-enveloped virus, was used to assess inactivation, while in the second study Bovine Viral Diarrhea Virus (BVDV), an enveloped virus, was utilized. In both experiments, the SFHb solution was deoxygenated and an aliquot of virus suspension was added. To initiate the crosslinking reaction, a solution of bis (3,5-dibromosalicyl) fumarate (DBBF) in HEPES buffer was added to the test solution. In both experiments the reaction times and the degree of crosslinking were normal. After crosslinking, the reaction mixtures were heated to 74 +/- 1 degrees C over 30 minutes, held at 74 +/- 1 degrees C for 90 minutes, and cooled to less than 10 degrees C over 30 minutes. In each experiment the degree of crosslinking of final product was 100% and yield of hemoglobin recovery was normal. Samples were removed prior to crosslinking, after crosslinking and before, during and after heat treatment for determination of virus titer and evaluation of key process parameters. The results from these experiments were consistent with those obtained from the full scale manufacturing process for the deoxygenation, crosslinking and the heat treatment step during the production of DCLHb. The results of virus assays showed that crosslinking has no effect on viruses and their subsequent inactivation by heat treatment.

Animals↗
PubMed1984

Heparin monitoring and neutralization during cardiopulmonary bypass using a rapid plasma separator and a fluorometric assay.

Avoidance of over- or underheparinization during cardiopulmonary bypass (CPB) is crucial in preventing bleeding or clotting. Currently no completely satisfactory method is available for measuring heparin levels--a method that would be rapid, inexpensive, specific, and reproducible. We combined the use of two devices, a rapid plasma separator and a fluorometric heparin assay system, in an attempt to satisfy these requirements in 15 patients having CPB during cardiac surgical procedures. The first instrument separates plasma from whole blood using a pneumatic filtration principle, while the heparin assay system measures the effect of heparin on thrombin conversion of a synthetic fluorogenic substrate. Accurate plasma heparin levels can be generated in less than five minutes, and the assays are inexpensive and easy to perform. Performing heparin assays at critical intervals during CPB allowed desired heparin levels to be maintained and the protamine dose for heparin neutralization to be reduced to a minimum. In addition, studies for heparin rebound revealed negligible rebound up to six hours postoperatively despite the reduced doses of protamine. There were no hemorrhagic or clotting complications in the series.

Cardiopulmonary Bypass↗
PubMed1983

A device for rapid plasma separation.

The STATSEP Plasma Separator (Instrumentation Laboratory, Inc, Lexington, MA), a device for rapidly separating plasma from whole blood, generates plasma at the rate of 0.5 ml/min by filtration rather than centrifugation. When plasma was separated by conventional centrifugation or by the plasma separator, there were no clinically significant differences in concentrations of a variety of important analytes in duplicate specimens. In addition, there were no clinically significant differences in measurements of prothrombin times (PT) and partial thromboplastin times (PTT) on plasmas generated by the 2 techniques. This device, therefore, reduces the analytic time of these frequent coagulation tests by 9 min. The above tests were performed on patients with leukemia and with benign and neoplastic elevations of platelet counts, with no differences seen between plasma specimens separated by either technique. Elevated hematocrits, however, require as much as 2 min to produce 0.5 ml of plasma. Both the machine and disposables are inexpensive and easy to operate.

Blood Chemical Analysis↗
PubMed1983

Anticoagulant monitoring and neutralization during open heart surgery--a rapid method for measuring heparin and calculating safe reduced protamine doses.

Confident monitoring of heparin during cardiopulmonary bypass and subsequent neutralization by protamine has been hampered by the absence of an accurate, reproducible, rapid, simple, and specific assay for heparin. By using two new instruments in tandem, one of which produced 0.5 ml of plasma in 1 min and one which specifically measures heparin in 3-4 min, heparin levels are available in approximately 5 min. By performing heparin assays at a variety of intervals, it was demonstrated that 76% of patients receiving common doses of heparin during cardiopulmonary bypass may have plasma levels that are potentially too low. Minimum neutralizing doses of protamine may be calculated using the formula: (estimated blood volume + pump prime volume) X (plasma heparin level/100) X 1.1 + 50. These doses were nearly two-thirds of previous doses and were unassociated with increased bleeding, clotting, or clinically significant heparin rebound.

Biological Assay↗
PubMedDate not supplied

Giant synovial cyst of the calf and thigh in a patient with granulomatous synovitis.

A giant synovial cyst with granulomatous synovitis was removed from the thigh and calf in an 80-year-old woman. The lesion included necrotizing, epitheloid cell granulomata with Langhans' type giant cells. Chest X-ray, tuberculin testing, cultures for Acid Fast bacilli, as well as aerobic, anaerobic and fungal cultures were all negative. The treatment consisted of synovectomy and total knee arthroplasty with an uneventful recovery. A giant calf cyst, usually associated with rheumatoid arthritis, but in this situation, noted in granulomatous synovitis seems not to have been reported previously.

Granuloma↗
PubMedDate not supplied

Measurement of plasma heparin levels using a fluorometric assay.

The performance of a fluorometric heparin assay system was evaluated. The system indirectly measures heparin by its inhibition of thrombin protease action on a synthetic substrate. Our results confirm that within the range of heparin concentrations recommended by the manufacturer, i.e., 0.1-0.8 units/ml, there is an excellent correlation between expected and observed values. Within-day coefficients of variation range from 1% to 2.6%; the between-day coefficient of variation is 6.5. The accuracy of the assay diminishes under 0.1 units/ml. The assay is not influenced by bilirubin, hemolysis, fibrin split products, or lipemia. Results can be generated in less than 5 min. Possible drawbacks are the wide range of acceptability for the supplied heparin standard, and the frequency of pipetting involved.

Fluorometry↗