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Biomedical subjects

D H Yawn

Publications and source records attributed to D H Yawn.

35 records · Page 2Linked to original sources
PubMed1983

Preoperative disseminated intravascular coagulation associated with aortic aneurysms. A prospective study of 76 cases.

A prospective study of 76 preoperative patients with aortic aneurysms was undertaken to determine the true incidence of associated disseminated intravascular coagulation (DIC). Although 39% of the patients showed a notable elevation of the fibrin split products level, only three had thrombocytopenia and a clinical bleeding diathesis, as well. Thus, clinically overt DIC occurred preoperatively in only 4% of the patients. All three patients had extensive aneurysms that involved the thoracoabdominal aorta. Preoperative fibrinogen levels in this series tended to be high-normal or elevated and were not good indicators of underlying excessive fibrinolysis. Hemostatic abnormalities, such as ecchymoses and petechiae, may be the key to the clinical diagnosis of DIC in preoperative patients with aortic aneurysms.

Aged↗
PubMed1981

Trimellitic anhydride Toxicity. A cause of acute multisystem failure.

A person exposed to trimellitic anhydride (TMA) an epoxy resin widely used in industry, experienced respiratory failure, anemia, and gastrointestinal bleeding. A lung biopsy specimen demonstrated intra-alveolar hemorrhage and damage to alveolar lining cells. The patient and six co-workers were examined. Results indicated the presence of hemolytic antibodies directed against TMA-haptenized erythrocytes, IgG, IgA, and IgM antibodies directed against TMA-erythrocyte complexes, and antibodies against TMA-human serum albumin. Antibody levels in the patient were greater than in the co-workers. The elevated antibody levels demonstrate the antigenic potential of TMA. However, the cause of the pulmonary and hematologic damage remains uncertain and may represent either immunologic or direct toxic effects of TMA. In patients with multisystem failure of this nature, occupational hazards should be added to the differential diagnosis.

Adult↗
PubMed1981

Propionibacterium acnes infection following subdural tap.

The case of an infant who had subdural hematomas that became infected with Propionibacterium acnes is reported. This is the second reported case of intracranial Propionibacterium acnes infection resulting from diagnostic or therapeutic manipulation.

Bacterial Infections↗
PubMed1979

Comparison of Brucella abortus and Brucella melitensis infections of mice and their effect on acquired cellular resistance.

By using mice infected with strains of Brucella abortus and Brucella melitensis we examined the histological responses to infection, the relationship of histology to persistence of organisms, and the relation of persistence of organisms to the acquisition of acquired cellular resistance (ACR). Infection with B. abortus resulted in well-formed granulomas in the livers, which persisted for more than 30 days. In contrast, infection with B. melitensis produced microabscesses in the livers which resolved before 30 days. The clearance of organisms from the tissues was also different. A total of 30 days after infection, large numbers of viable bacteria were recovered from the tissues of B. abortus-infected mice whereas bacteria were no longer recoverable from B. melitensis-infected animals. ACR to Listeria monocytogenes, another intracellular pathogen, persisted for more than 30 days in B. abortus-infected mice but waned rapidly in B. melitensis-infected animals. This disappearance of ACR due to B. melitensis paralleled the clearance of bacteria from the tissues.

Animals↗
PubMed1977

Experimentally induced bleomycin sulfate pulmonary toxicity: histopathologic and ultrastructural study in the pheasant.

Morphological alterations in the lungs of pheasants after prolonged high-dosage administration of bleomycin sulfate were studied by light and electron microscopy. Nontreated birds acted as controls, and their lungs showed no abnormalities. Lungs of bleomycin-treated pheasants revealed collapse alternating with overexpansion, marked cuboidalization of atrial epithelium, and incipient interstitial fibrosis. There were neither lymphoplasmacytic or eosinophilic infiltrates, nor evidence of vasculitis. Ultrastructurally, type 1 alveolar epithelial cells were either reactive or conspicuously absent in the air capillaries. Type 2 alveolar epithelial cells appeared hyperplastic with numerous lamellar bodies, many of which extruded into air spaces. Immature fibroblasts were noted in the vicinity of collagen fibrils or amorphous material resembling elastin. No immune deposits were present in basement membranes. These findings are consistent with a direct toxic effect of bleomycin to the pheasant lung rather than a drug hypersensitivity reaction. Reproduction of the bleomycin lesion in a nonmammalian species corroborates even further the high propensity of the drug to affect the lung.

Animals↗
PubMed1972

Structural alteration in isolated rat liver nuclei after removal of template restriction by polyanions.

Specific polyanions release DNA template restrictions for DNA synthesis in isolated rat liver nuclei. The degree to which DNA synthesis is enhanced can be correlated with a spectrum of changes in nuclear structure Each polyanion which is effective in the release of template restriction produces a characteristic alteration in nuclear ultrastructure. Polyanions which have no effect on DNA synthesis do not appear to cause any change in nuclear organization or ultrastructure. Parallel measurements of nuclear DNA release and nuclear volume changes also indicate that template-activating polyanions cause remarkable changes in the structural organization of the treated nuclei. These results indicate that DNA template activation involves direct interactions between polyanions and nuclear constituents and suggest the possibility that naturally occurring polyanions might have a role in the control of gene activity

Animals↗
PubMed1967

Morphological and biochemical studies of isolated mitochondria from fetal, neonatal, and adult liver and from neoplastic tissues.

A combined morphological and biochemical investigation of mitochondria from developing and rapidly growing tissues ( tumors, fetal, and very early neonatal rat liver) revealed mitochondria which were deficient in respiratory control, showed no valinomycin induced K(+) accumulation or spontaneous Ca(++) uptake, and were unable to undergo a swelling-contraction cycle. Electron microscopic examination of fetal and neonatal livers and a mammary tumor revealed mitochondria which differed from controls with respect to matrix density and ability to undergo reversible structural changes. The importance of isolation and assay media in interpretation of results is emphasized.

Animals↗
PubMedDate not supplied

Cost comparison of intraoperative autologous versus homologous transfusion.

The cost of autologous transfusions using semiautomated instruments in 52 orthopedic cases, 75 coronary artery bypass graft (CABG) cases, and 218 aortic aneurysm cases was compared to the cost of equal amounts of homologous blood. While none of the orthopedic cases reached cost equivalence (median cost deficit per case, +97), 31 percent of the CABG cases (median cost deficit per case, +61) and 56 percent of the thoracic aortic aneurysm cases (mean cost surplus per case, +30) did so. In most cases, the major orthopedic and CABG procedures do not reach cost equivalence and might be served better by other means of autologous blood recovery. The more expensive semicontinuous flow devices are more cost-effective for higher-yield cases, such as major aortic aneurysm procedures.

Blood Cells↗
PubMedDate not supplied

Effect of profound hypothermia on leukocytes and platelets.

Seventeen patients who underwent aortic arch replacement were subjected to profound hypothermia and circulatory arrest. At maximum cooling, platelet count dropped from 184 +/- 122 to 37 +/- 30 thousand per microliter, and the total leukocytic count fell from 6.27 +/- 4.0 to 1.47 +/- 0.6 thousand per microliter. The thrombocytopenia was partially reversed with rewarming. The total white cell count consistently returned to precooling values or higher (10.5 +/- 4.0). The mechanism for this cold induced phenomenon is not well understood.

Aorta, Thoracic↗
PubMedDate not supplied

Heparin monitoring during cardiopulmonary bypass.

Three procedures have been compared for monitoring heparin in patients undergoing cardiopulmonary bypass: (1) activated clotting time (ACT) (2) protamine titration, and (3) fluorometric substrate assay. The ACT monitors the degree of anticoagulation. It is easy to perform and is relatively inexpensive, however, it does not correlate well with heparin levels and may not accurately predict the protamine dose for neutralization of heparin at the completion of bypass. A protamine titration assay or an assay using a thrombin-sensitive fluorometric substrate measures the heparin level and calculates the protamine requirement at the completion of surgery; however, these assays do not indicate the degree of anticoagulation. The fluorometric assay is the less expensive of the two assay measuring heparin, but it requires an experienced technologist to perform the test.

Cardiopulmonary Bypass↗
PubMedDate not supplied

Viscoelastic measurement of clot formation: a new test of platelet function.

Assessment of platelet function presents a challenge to the investigators in the clinical field. An instrument, Sonoclot, is described which measures changes in the viscoelastic properties (clot impedance on a vibrating probe) of plasma as it is recalcified. Platelet poor plasma (PPP) and platelet rich plasma (PRP) show distinct and characteristic Sonoclot tracings. Tracings of PPP show a lag period and a primary wave. These parameters correspond to recalcification time and fibrin polymerization. Tracings of PRP show, in addition, a secondary wave and a downward wave. These parameters correspond to the incorporation of platelets in the clot and retraction of the clot. The PRP parameters are influenced by the number and quality of the platelets. This instrument was utilized to assess the platelet function in patients after coronary artery bypass surgery (CAB). In 69 patients studied, 20 patients did not have excessive bleeding. The clot impedance tracings in this group were normal. Twenty-four patients had excessive bleeding, normal clot impedance, and coagulation tests indicating the possibility of surgical bleeding. This was confirmed in 22 (92 percent) patients upon exploration to control bleeding. Twenty-five patients had excessive bleeding, normal coagulation tests and abnormal clot impedance suggesting platelet dysfunction. In twenty-one (84 percent) of the patients, transfusion of platelet concentrate controlled the bleeding with corresponding correction of clot impedance. Sonoclot studies are quick and easy to perform, and appear to be a valuable and reliable adjunct in the diagnosis of hemostatic problems after CAB surgery.

Bleeding Time↗