PubMed Health⌕ Search

Biomedical subjects

J L David

Publications and source records attributed to J L David.

17 recordsLinked to original sources
PubMed1991

The use of perfluorodecalin in diabetic vitrectomy.

Nine patients were operated on for severe proliferative diabetic retinopathy using a perfluorocarbon liquid, purified perfluorodecalin; 7 patients were operated on for traction-rhegmatogenous retinal detachment, 2 for severe fibrovascular proliferation complicated intraoperatively by iatrogenic holes with surrounding retinal detachment. The intraoperative use of perfluorodecalin allowed flattening of the retina and endophotocoagulation to be carried out easily. Perfluorodecalin was removed at the end of the procedure, and intraocular tamponade was provided by silicone oil in 5 eyes and by a long-acting gas in 4 eyes. Anatomic success was obtained in 8/9 cases with a minimum follow-up of six months; 4 eyes had improved vision, 2 had the same vision, and 3 had decreased vision. The main advantage of intraoperative use of perfluordecalin is to allow easy flattening of the retina and effective endophotocoagulation under optimal visual conditions.

Adult↗
PubMed1990

Hemostasis profile in women taking low-dose oral contraceptives.

Thirty-six young, healthy, nonsmoking women have been selected to check the effect of low-dose oral contraceptives on hemostasis. Two identical groups were treated by Marvelon (a monophasic oral contraceptive containing ethinyl estradiol and desogestrel) or Trigynon (a triphasic oral contraceptive containing ethinyl estradiol and levonorgestrel) for a 6-month period. In the absence, previously controlled, of substantial differences between the effects of each treatment on hemostasis, all the results were pooled at the third and sixth month of the study. The effects of oral contraceptive treatment were as follows: (1) platelet number, platelet aggregating ratio, and plasma beta-thromboglobulin level were not significantly altered, and (2) antithrombin III activity was not reduced despite a slight decrease or antigen concentration. The von Willebrand factor parameters, factor VIII:C, factor VII:C, and clottable fibrinogen were significantly increased. Plasminogen (activity and antigen concentrates) and alpha 2-antiplasmin levels were also significantly increased. Activated partial thromboplastin time and euglobulin lysis time measured after venous occlusion were significantly shortened. Although statistical analysis did not show dramatic changes in all these parameters, some individual extreme values were substantially altered. Therefore we believe that these later values are worthy of cautious consideration for weighing the role that hemostasis factors might play in individual thrombotic risk.

Adult↗
PubMed1990

Heparin-induced thrombocytopenia: a case report.

The authors report a case of heparin-induced thrombocytopenia, in whom massive pulmonary embolism occurred in spite of heparin anticoagulation. Successful pulmonary thrombectomy was carried out under cardiopulmonary bypass, with limitation of platelet clumping during bypass by aggregation inhibitors. This report is a comprehensive contribution to a better understanding of this rare immunoallergic complication of heparin administration, with a high incidence of serious thromboembolic events. The optimal management for cases of unavoidable reexposure to heparin is discussed.

Drug Hypersensitivity↗
PubMed1988

Lectin-like binding of pertussis toxin to a 165-kilodalton Chinese hamster ovary cell glycoprotein.

Chinese hamster ovary (CHO) cells cluster in the presence of pertussis toxin, a response that is correlated with the ADP-ribosylation of a Mr = 41,000 membrane protein by the toxin. A ricin-resistant line of CHO cells (CHO-15B) which specifically lacks the terminal NeuAc----Gal beta 4GlcNAc oligosaccharide sequence on glycoproteins did not cluster in response to pertussis toxin. These cells do contain the Mr = 41,000 protein substrate for the enzymatic activity of the toxin which suggests that pertussis toxin, like certain plant lectins, does not bind to or is not internalized by the CHO-15B cells. There was no evidence of pertussis toxin binding to gangliosides or neutral glycolipids isolated from CHO cells but the toxin bound to a Mr = 165,000 component in N-octyglucoside extracts of CHO cells that had been separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electroblotted to nitrocellulose. Plant lectins from Ricinus communis and Erythina cristagalli detected a similar size band in CHO cells and also did not react with CHO-15B cells. Unlike pertussis toxin, these plant lectins recognized two other major bands in CHO cell extracts and reacted best after sialidase treatment of nitrocellulose transfers containing CHO cell extracts. Conversely, sialidase treatment abolished binding a pertussis toxin and wheat germ agglutinin, a plant lectin that reacts with multivalent sialic acid residues on glycoproteins, to the Mr = 165,000 band. Purified B oligomer of pertussis toxin also uniquely detected a Mr = 165,000 component in CHO cell extracts while the A subunit of pertussis toxin was unreactive. These results indicate that pertussis toxin binds to a CHO cell glycoprotein with N-linked oligosaccharides and that sialic acid contributes to the complementary receptor site for the toxin. In addition, they suggest that a glycoprotein may serve as a cell surface receptor for pertussis toxin and that this interaction is mediated by a lectin-like binding site located on the B oligomer.

Adenosine Diphosphate Ribose↗
PubMed1988

Comparison of type 2 and type 6 fimbriae of Bordetella pertussis by using agglutinating monoclonal antibodies.

Two types of fimbriae have been identified on the pathogenic gram-negative organism Bordetella pertussis. Monoclonal antibodies to these fimbriae were produced to better understand the role of fimbriae as serotype-specific agglutinogens and to investigate the antigenic relationship between these fimbriae. Three monoclonal antibodies were identified that specifically agglutinated B. pertussis cells containing the U.S. Reference Factor 2 agglutinogen, and six monoclonal antibodies were produced that agglutinated only those strains containing the U.S. Reference Factor 6 agglutinogen. Indirect immunofluorescence studies and immunogold electron microscopy demonstrated that these monoclonal antibodies bind to an outer membrane component on serotype-specific strains of B. pertussis. All of the monoclonal antibodies reacted with native or partially assembled type-specific fimbriae but not with monomeric fimbrial subunits as indicated by Western blot (immunoblot) analysis. The fimbrial agglutinogens recognized by the monoclonal antibodies were also uniquely reactive with either U.S. Reference Factor 2 or 6 antiserum (Eldering agglutinogen 2 or 6 polyclonal antiserum) in an indirect ELISA. No cross-reactivity of the monoclonal antibodies with the unrelated fimbriae was observed in any of the comparative immunological studies. Some of the monoclonal antibodies agglutinated certain strains of B. bronchiseptica, suggesting that this closely related species can contain antigenically similar fimbriae. These monoclonal antibodies should prove useful for further structural and functional analysis of Bordetella fimbriae and for studies on the role that these antigens play in prevention of infection and disease.

Agglutination Tests↗
PubMed1987

Prevention of aorta-coronary bypass graft occlusion. Beneficial effect of ticlopidine on early and late patency rates of venous coronary bypass grafts: a double-blind study.

The efficacy of coronary bypass grafting obviously being linked to graft patency, it is compulsory to look for any innovation that could improve the patency rate. Ticlopidine, an antiplatelet drug, was tested against placebo in a double-blind trial: 173 patients (475 grafts) subjected to venous coronary artery bypass grafting were randomly treated with ticlopidine (250 mg twice daily) or placebo from the second postoperative day for 12 months. Graft patency was assessed by digital angiography on days 10 (99.4% of the patients), 180 (98.2%), and 360 (91.7%). The effect of treatment on platelet aggregation and bleeding time were measured concomitantly; a clear-cut effect was demonstrated at each interval. Intention-to-treat graft-by-graft analysis shows that ticlopidine significantly reduced the graft occlusion rate on day 10 (7.1% versus 13.4%, p less than 0.05), day 180 (15.0% versus 24.0%, p less than 0.02), and day 360 (15.9% versus 26.1%, p less than 0.01). Sequential grafts to the left anterior descending coronary artery, with side-to-side anastomosis to diagonal branch(es), are less frequently occluded than individual grafts. On the contrary, grafts to endarterectomized vessels occlude more frequently. Individual patient-by-patient analysis shows that patency of all grafts at each study time, is more frequent in the ticlopidine group. The difference is significant when one considers patients without sequential or endarterectomized grafts. The difference is also present at each study time: day 10 (84.4% versus 66.7%, p less than 0.05), day 180 (74.4% versus 52.3%, p less than 0.05) and day 360 (75.0% versus 52.5%, p less than 0.05). Results are even more impressive if one excludes from analysis the four patients in the ticlopidine group in whom administration of the drug was delayed. This supports previous suggestions that early therapy is necessary. These results show that graft occlusion occurs mainly in the first 6 postoperative months. The incidence of occlusion is significantly reduced by ticlopidine therapy.

Angiography↗
PubMed1985

Subacute subdural hematoma as the first symptom in a child with hemophilia A.

The authors reported a case of subacute subdural hematoma in a 14-month-old child suffering from mild hemophilia (Factor VIII, activity: 2.5%). Removal of hematoma under the cover of replacement therapy has been performed safely and has led to recovery without any clinical sequelae. Computerized tomography appeared very useful as an atraumatic method of examination in hemophiliacs. Discussion deals with the problems associated with management of intracranial hemorrhages in hemophiliacs and emphasizes the need of prompt adequate medical and surgical treatment to prevent irreversible damage to the brain.

Brain Damage, Chronic↗