Thromboxane synthetase inhibition in acute focal cerebral ischemia in cats

✓ The purpose of this investigation was to study the effects of a selective thromboxane A2 (TXA2) synthetase inhibitor (TSI) upon the evolution of cerebral infarction in the cat. Adult cats, lightly anesthetized with nitrous oxide, underwent right middle cerebral artery (MCA) occlusion for 4 hours followed by a 2-hour period of reperfusion before sacrifice. Ten cats received 3 mg/kg TSI intravenously immediately before, and 10 cats received 3 mg/kg TSI intravenously immediately after MCA occlusion. Ten cats were used as controls receiving no treatment. The bleeding time was determined at baseline and at the end of each experiment. Electroencephalographic (EEG) recordings were obtained before and after MCA clipping and MCA release, and at hourly intervals thereafter. Regional cerebral blood flow (rCBF) was measured using the xenon-133 (133Xe) clearance technique before and after MCA occlusion, after MCA reopening, and before terminating each experiment. Thirty minutes before each cat was sacrificed, Evans blue dye and sodium fluorescein were given intravenously. The animals were then perfused with colloidal carbon and the brains removed and evaluated for midline shift, Evans blue dye and sodium fluorescein extravasation, carbon staining, and infarct size. The bleeding time, arterial blood pressure, rCBF changes, brain swelling, and vital dye extravasation were not statistically different between the three treatment groups. The EEG changes, carbon staining, and infarct size differences between the three groups also failed to reach statistical significance, but there was a suggestion that these parameters were adversely affected in the cats pretreated with TSI. Ten additional cats undergoing MCA occlusion and reperfusion were used for pharmacological studies. Five of them received 3 mg/kg TSI intravenously immediately after MCA occlusion, and serial drug and thromboxane B2 (TXB2) levels (a stable metabolite of TXA2) were determined. Another five cats were not treated and serial TXB2 levels were obtained. Production of TXA2 was inhibited by 95% in cats receiving TSI. In conclusion, thromboxane synthetase inhibition failed to modify favorably the evolution of cerebral infarction. When TSI was given before MCA occlusion, cerebral infarction tended to be more extensive.

Immunophenotypic characterization of acute leukemia by immunocytology

The potential for specific immunophenotypic characterization of the acute leukemias has been enhanced greatly by the development of monoclonal antibodies. Currently, this immunologic data is obtained most commonly by flow cytometric analysis or cellular cytotoxicity assays. The former is an expensive technic that lacks morphologic evaluation unless cell sorting is performed. The latter precludes morphologic assessment by the nature of the assay. The authors have developed an immunostaining procedure utilizing cytospin preparations and immunoperoxidase methods that are relatively inexpensive and allow simultaneous assessment of the immunologic markers and cellular morphology. Although a comparison of flow cytometry and immunocytology revealed quantitative differences for individual cell surface markers, the "qualitative" immunologic phenotype of the leukemic population was virtually identical by the two technics.

A comparative study of the use of fluorescein and the Doppler device in the determination of intestinal viability

Fluorescein is a reliable indicator of mucosal viability in dogs. This fact is probably applicable to humans. The Doppler device was not a reliable predictor of intestinal nonviability, and in the instance of mesenteric venous occlusion, with ischemic intestine, it was totally inaccurate in assessing intestinal viability. Short segments of intestine failing to take up fluorescein stain will retain viability, owing to the lesser nutrient requirements of resting smooth muscle. However, segments should not be used for anastomoses, since the mucosa will, to some degree be ischemic.

Isolation of prostacyclin from whole blood

A method was development for the isolation of prostacyclin (PGI2) from whole blood in a fraction suitable for high pressure liquid chromatography (HPLC) separation of PGI2 and 6-keto-prostaglandin F1 alpha (6-K-PGF1 alpha). Prostacyclin was stabilized in whole blood by rapidly raising the pH to 10 with Na2CO3 and cooling the samples to 0 degree C. Under these conditions, 2.9% hydrolysis was observed after 20 min. Reverse phase extraction columns were used to directly extract both PGI2 and 6-K-PGF1 alpha from the alkaline plasma with recoveries of greater than 95% using an acetonitrile/2mM Na2B4O7, pH 10, 40/60 elution solvent mixture. An additional 1.7% hydrolysis was found during the column extraction procedure. Final separation of PGI2 and 6-K-PGF1 alpha was performed with HPLC using an alkaline solvent system. This method is capable of rapidly and efficiently extracting and separating PGI2 and 6-K-PGF1 alpha from whole blood or plasma. It introduces less than 5% hydrolysis of PGI2, thus providing a means of applying highly sensitive 6-K-PGF1 alpha assays to the determination of PGI2 levels in physiological samples.

Platelet-bound IgG in systemic lupus erythematosus with and without thrombocytopenia

A new assay for IgG bound to autologous platelets is described, in which IgG is dissociated from platelets washed at low pH, then measured by radioimmunoassay. Platelet-bound IgG was found to be elevated in thrombocytopenic patients with SLE and reduced in non-thrombocytopenic patients with this disease. There was a close inverse correlation of platelet-bound IgG and platelet count. Immune complexes did not interfere with the assay.

Morphology and cytochemistry of "microgranular" acute promyelocytic leukemia (FAB M3m)

Three cases of a newly recognized "microgranular" variant of acute promyelocytic leukemia (FAB M3) are described. This poor-prognosis variant is easily confused with myelomonocytic (M4) or monocytic (M5) leukemia, but is associated with disseminated intravascular coagulation as is "hypergranular" M3. Such patients may be inappropriately treated unless the promyelocytic nature of the leukemia is recognized.

Alternate chromogens as substitutes for benzidine for myeloperoxidase cytochemistry

Myeloperoxidase staining methods for classification of leukemias have traditionally employed benzidine dihydrochloride as the chromogen. Recent Occupational Safety and Health Administration regulations have classified benzidine as a carcinogen, which severely restricts its use in the clinical laboratory. Twenty-two specimens from normal control subjects and leukemia patients, previously classified by FAB criteria, were stained with benzidine and two alternate chromogens, diaminobenzidine and Hanker-Yates reagent (p-phenylenediamine and pyrocatechol). In a random, blind fashion, three experienced observers scored the stains from each case according to quality of smear, degree of peroxidase positivity, tinctorial distinction between nucleus and cytoplasm, and overall acceptability of the stain. All three observers rated the substitute chromogens as adequate for routine myeloperoxidase cytochemical staining. It is concluded that either of the methods studied would have clinical utility and can substitute for benzidine as a myeloperoxidase chromogen.

The contrecoup phenomenon. Reappraisal of a classic problem

We describe briefly and comment upon the salient strengths and limitations of the major published theories that purport to explain the mechanism of contrecoup cerebrocortical contusions. Through the application of mechanical principles, we then present a modification, clarification, and expansion of selected aspects of several theories. Our final formulation emphasizes the injurious potential of nonuniform compressive stress and the relationship between brain lag and rotationally induced injury. The resulting theory remains faithful to the laws of physics while explaining the location and distribution of cerebrocortical contusions opposite the site of a moving head impact.

Six-year program shows benefits of shared laboratory services

The VA Hospital in Columbia, MO, and the University of Missouri Medical Center conduct the largest shared laboratory service in the VA hospital system. Sharing has enabled these institutions to eliminate unnecessary duplication of resources, develop new laboratory capabilities in subspecialties, handle additional routine procedures, better use the expertise of senior staff pathologists, develop uniform standards, enhance quality assessment, and expand training programs.

Ultrastructure of chick tendon fibroblast with special reference to secretory mechanism

Electron-microscope study of chick tendon fibroblast revealed a constant ultrastructural finding of a microtubular-microfibrillar system and an intimate relationship which existed between the microtubular-microfibrillar system and secretory vacuoles. Additionally, the data from this study suggest a mechanism by which newly synthesized collagen molecules are transported and secreted into the extracellular space to be organized into mature collagen.

Inflammatory carcinoma of the breast

Fifty-eight patients with clinical inflammatory breast carcinoma and 15 patients with "occult" inflammatory cancer (dermal lymphatic carcinomatosis without clinical inflammation) are grouped and reviewed to determine whether diagnosis is pathologic or clinical. All cases represent a retrospective study of records from the Ellis Fischel State Cancer Hospital, Columbia, Missouri. Lesions of clinically apparent and occult inflammatory carcinoma demonstrate similar gross and microscopic growth patterns, histologic types, axillary involvement and early widespread metastases. Regardless of pathologic evidence of dermal lymphatic tumor, patients with clinical inflammation had rapid deterioration. Cases with only a pathological diagnosis were slightly less fulminant in progression. Either clinical or pathologic criteria justify use of the term "inflammatory breast carcinoma" to indicate short-term prognosis despite available treatment.

A three-dimensional study of endometrial mitochondria during the menstrual cycle

Three-dimensional reconstruction of endometrial mitochondria during the menstrual cycle in the woman has produced three mitochondrial populations. These populations are seen to change in size, in number, and in complexity of structure as the menstrual cycle progresses. Through reconstruction and statistical analysis, morphologic data seem to support histochemical data relating to anaerobic and aerobic metabolism in endometrial gland cells.

Evolution of human cytogenetics: an encyclopedic essay. III. The second decade after 1956: banding techiques

Unequivocal establishment of the correct diploid chromosome number in 1956 started the modern era of human cytogenetics. The next impetus came when the peripheral blood leukocyte culture technique for the chromosome preparation was described in 1960. Discovery of special staining procedures - banding techniques - in early seventies not only saved it from early senescence but played decisive roles in broadening the horizons of modern human cytogenetics.