Heterogeneity of human whole blood platelet subpopulations. III. Density-dependent differences in subcellular constituents

Structurally intact platelet cohorts of differing densities can be isolated from normal subjects by the use of isosmolar arabinogalactan density gradients. Using platelets separated in this fashion, we have studied the density-dependent distribution of four subcellular organelles: mitochondria, lysosomes, dense bodies, and alpha granules. Mitochondria, which are not secreted during platelet release, demonstrate a slow decline in monoamine oxidase activity within the gradient. Lysosomal beta-glucuronidase does not vary significantly with platelet density. In contrast, dense body number and endogenous serotonin content decrease significantly with decreasing platelet density, primarily as the result of differences in the number of storage organelles. Platelet factor 4 content declines rapidly in comparison to lysosomal activities (P less than .001 from bottom to top of the gradient); but beta-thromboglobulin, also an alpha granule component, exhibits considerably less change than platelet factor 4 (P less than .001). Thus, specific platelet subcellular constituents have different density distributions. We postulate that these density differences may be due to differential in vivo loss of selective biochemical constituents from unique subcellular compartments.     

The effect of PGI2 and theophylline on the response of platelets subjected to shear stress

A specially designed rotational viscometer was used to investigate the effects of the antiplatelet agent PGI2 in combination with theophylline on the response of human platelets subjected to shear stress. Samples of citrated platelet-rich plasma (PRP) were exposed to shear stress in the viscometer for a period of 5 min at 23 degrees C. The levels of stress studied ranged from 50 to 300 dynes/sq cm. Pretreatment of the platelets with 0.01 microM PGI2 and 500 microM theophylline before exposure to shear stress caused a large reduction in shear-induced platelet aggregation. However, it was also observed that the PGI2-- theophylline pretreatment concomitantly caused a large increase in shear-induced platelet lysis and serotonin release at stress levels equal to or greater than 150 dynes/sq cm. This observed increase in platelet fragility may have important implications for clinical applications of PGI2. The results are discussed and compared to those obtained in prior work in which platelets were pretreated with acetylsalicylic acid or with PGE1.     

The surgical anatomy of the middle nasal meatus

Summary An exact study was made of the middle nasal meatus in 20 anatomical preparations (left and right) from 10 subjects. Some features (the ethmoidal bulla, the uncinate process of the ethmoidal bone, the openings of the maxillary and frontal sinuses) are relatively constant in their arrangement, but very variable in shape and size. An understanding of these structures is now essential for the practice of endonasal microsurgery.

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De l'anatomie médicochirurgicale du méat nasal moyen

Résumé Une série de 20 préparations anatomiques gauche et droite sur 10 sujets a permis une observation précise du méat nasal moyen. Certains reliefs: la bulle ethmoïdale, le processus uncinatus, les méats des sinus maxillaire et frontal sont relativement fixes dans leur disposition, mais très variables dans leur forme et leurs dimensions. Leur connaissance est maintenant indispensable à tout praticien exerçant la microchirurgie endonasale.

     

Perinatal outcomes in inflammatory bowel disease

Objective: To determine whether inflammatory bowel disease (IBD) is associated with increased risk for adverse perinatal outcome.

Methods: A case–control study of 116 singleton pregnancies with IBD compared to 56?398 singleton controls delivered between 1986 and 2001.

Results: Patients with IBD were slightly older (32.8 vs. 30.6 years, p <?0.001), more likely to be Caucasian or Asian than Black or Latino (92% vs. 57%, p <?0.001) and have private health insurance (33% vs. 3%, p <?0.001). IBD was associated with an increased risk for labor induction (32% vs. 24%, p?=?0.002), chorioamnionitis (7% vs. 3%, p?=?0.04) and Cesarean section (32% vs. 22%, p?=?0.007), but there were no differences in neonatal outcomes. Subgroup analysis demonstrated an increased risk for low birth weight (LBW) in the ulcerative colitis group vs. the Crohn's disease group (19% vs. 0%, p?=?0.002). Patients with prior surgery for IBD had a lower incidence of LBW (0% vs. 12%, p?=?0.03). Flares during pregnancy were associated with an increased risk for preterm delivery (27% vs. 8%, p?=?0.02) and LBW (32% vs. 3%, p?=?0.003).

Conclusion: IBD was an independent risk factor for Cesarean section but there was no increase in adverse perinatal outcome. Crohn's disease, prior IBD surgery and quiescent disease were associated with a lower risk for LBW.     

Image-directed percutaneous biopsies with a biopsy gun

Core tissue for histologic study is believed by many pathologists to be more diagnostic than material from needle aspiration. Recently, a biopsy "gun" has been introduced, which simplifies core biopsies. With this device, 182 biopsies of multiple anatomic sites were performed with ultrasonic, computed tomographic, and fluoroscopic guidance and 18-gauge needles. High-quality histopathologic specimens were obtained in 177 of the biopsies, and diagnostic target tissue was obtained in 167. Only three significant complications occurred: one bleeding complication that required transfusion and two cases of pneumothorax that necessitated placement of chest tubes. The biopsy gun eliminated the disjointed movements of conventional "skinny" needle biopsies, and none of the samples demonstrated significant "crush" artifact or obscuring blood, problems that are commonly associated with manual biopsy techniques. Patient discomfort was decreased with this system compared with that of manual biopsies, and the total procedure time was reduced. Because of these distinct advantages, the authors now use the biopsy gun exclusively for all percutaneous biopsies and recommend that other institutions consider the use of this biopsy method.     

P53 gene mutations in acute myeloid leukemia with 17p monosomy

We looked for mutations of exons 5 to 8 of the P53 gene in 10 patients with acute myeloid leukemia (AML) and 17p monosomy, and 36 patients with AML and no cytogenetic abnormalities of 17p. DNA was analyzed by polymerase chain reaction, single-strand conformation polymorphism analysis, and nucleotide sequencing. Four of the 10 patients with 17p monosomy showed point mutation, single-nucleotide deletion, or insertion in exons 7 or 8. By contrast, only 1 of the 36 patients with AML and no cytogenetic abnormalities of 17p showed a mutation of the P53 gene in exons 5 to 8 (P less than .01). These results suggest that alterations of the P53 gene may have a role in leukemogenesis in some cases of AML. The fact that P53 gene mutations occurred more often in patients with 17p monosomy seems to support the "recessive" model of tumor suppressive activity of the P53 gene rather than the "dominant" model, in which alteration of only one allele is sufficient for the development of malignancy.     

Lipomatous tumors of the liver: evaluation with CT and US

Seven cases of lipomatous masses within the liver parenchyma were demonstrated with computed tomography (CT). Five of these cases were obtained from a retrospective review of 50 cases of renal angiomyolipoma in which the liver was adequately demonstrated. The other two cases were from the files of the Armed Forces Institute of Pathology and had no associated renal lesions. Three of the five cases were associated with tuberous sclerosis. In all seven cases, the fatty tumors appeared on CT scans as a well-defined, 0.8-13-cm mass, with attenuation coefficients of less than -30 HU. On ultrasound studies, the lesions were well circumscribed, highly echogenic, and similar to hemangiomas. While distinctly rare lesions, these lipomatous masses are not as unusual as the literature would indicate. One may anticipate such masses in patients with renal angiomyolipomas and in a relatively high percentage of those with tuberous sclerosis.