Summary. The purpose of this study was to elucidate the effect of neuraminidase on circulating platelets in rats and the pathogenesis of this effect. Injection of bacterial, purified bacterial and viral neuraminidase caused thrombocytopenia of various degrees. Thrombocytopenia was less pronounced in rats given viral neuraminidase and in splenectomized animals. A dose‐response effect was seen only with purified bacterial neuraminidase injected intravenously. Ultrastructural studies of blood platelets were performed after injection of neuraminidase. Fifteen minutes after injecting neuraminidase, before a definite fall in the count, platelets showed evidence of structural damage such as irregular shapes, centripetal migration and fusion of granules and bleb formation. The structural alterations were progressive, reaching a maximum at about 2–4 hr. At no time were large platelet aggregates observed in the circulating blood. Four hours after injection of neuraminidase, when the platelet count dropped significantly, many platelets had normal ultrastructurc. By 24 hr, the majority of circulating platelets appeared normal; however, the splenic sinusoids and macrophages contained platelets with the same structural abnormalities seen in the circulation 15 min to 2 hr after injection of neuraminidase. We conclude that neuraminidase alters the platelet membrane resulting in its rapid and permanent removal by the reticuloendothelial system.
Bone marrow specimens from four cases of pure monocytic leukaemia (Schilling type) and three cases of myelo-monocytic leukaemia (Naegeli type) were examined by electron microscopy. The hallmark of the monoblasts and more mature monocytoid forms was the extreme nuclear irregularity with frequent nuclear bridges and blebs. Abundant cytoplasm with a serrated margin, dense granules, numerous pinocytic vesicles and vacuoles, frequent peri-nuclear fibrillar bands and a well-developed Golgi zone served as additional criteria for identifjring monoblasts. Various stages in the maturation of monoblasts were observed. Stem cells possessed a large round nucleus which became extremely folded with increasing maturity. The gradual appearance of condensed chromatin paralleled this nuclear polymorphism. The fine structure of these monoblasts was compared with that of myeloblasts to point out distinguishing features. It is felt that ultrastructural analysis can be of value in separating pure monocytic leukaemia from myelo-monocytic leukaemia.Reschad & Schilling-Torgau (1913) first described monocytic leukaemia. Downey later separated monocytic leukaemia into two types-a pure monocytic leukaemia which he termed Schilling typeand a mixed myelo-monocytic which he termed Naegeli type (Downey, 1938; Watkins & Hall, 1940). The diagnosis of monocytic leukaemia is based on the presence of large numbers of monocytoid as well as related blast forms. In the pure form, these comprise over 60% of the white blood cells (Wintrobe, 1967;Clough, 1932). At present, despite special stains, there is occasional difficulty with light microscopy in differentiating pure monocytic from myelo-monocytic leukaemia. In fact, some maintain that the true incidence of pure monocytic leukaemia is much higher than usually reported, due to misdiagnosis as myelo-monocytic leukaemia (Osgood, 1969).To date, there have only been fragmentary reports on the ultrastructure of monocytic leukaemia (Freeman
Abstract— Nuclei from adult rat brains isolated with isotonic sucrose were incubated with [3H]leucine and later purified by centrifugation through hypertonic sucrose solutions. It was found that under these conditions, tritiated leucine was incorporated into TCA precipitable material. Protein synthesis was impaired if the nuclei were treated with the nonionic detergent Triton X‐100 or hypertonic sucrose. The presence of puromycin or cycloheximide markedly inhibited the incorporation of the radioactive amino acid. Actinomycin D and RNase did not have any effect on the incorporation. Autoradiography indicated the presence of labelled material within the nuclei and not in cytoplasmic contaminants. Glial nuclei were more actively involved in protein synthesis than neuronal nuclei.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.