Neurofibromatosis 1 (NF1) is an autosomal dominant tumor predisposition
syndrome in which affected individuals have a greatly increased risk of
developing malignant peripheral nerve sheath tumors (MPNSTs). These
cancers are difficult to detect and have a poor prognosis. Because
patients may present to specialists from widely differing disciplines,
the association with NF1 is often not appreciated, and there is no
cohesive pattern of care. A multidisciplinary group of 33 clinicians
and scientists with specialist knowledge in MPNST and NF1 reviewed the
current published and unpublished data in this field, and distilled
their collective experience to produce a consensus summary on MPNST in
NF1. The known clinical, pathological, and genetic information on MPNST
in NF1 was collated, and a database was established to record
information in a uniform manner. Subgroups with a higher risk of
developing MPNST were identified within the NF1 population. The
consortium formulated proposals and guidelines for clinical and
pathological diagnosis, surgical management, and medical treatment of
MPNST in individuals with NF1. A multidisciplinary team approach to the
management of this complex disorder is advocated. Progress can be made
by adopting the guidelines proposed by this consortium and by
widespread dissemination of standardized information. Collaborative
research should be promoted with the aim of harnessing advances in
molecular genetics to develop targeted therapies for MPNST in people
with NF1.

https://cancerres.aacrjournals.org/content/canres/62/5/1573.full.pdf

International consensus statement on malignant peripheral nerve sheath tumors in neurofibromatosis.

Secondary thickening in pteridophytes.-The known cases of secondary thickening in recent Pteridophyta have been brought together by HILL23 in a useful resume. After stating the criteria for secondary growth, Botrychium, which has a distinct cambium, and Ophioglossum, which lacks a definite layer, are described, followed by Angiopteris and Marattia, in which a cambium forms a few xylem elements. CORMACK'S observations on the secondary wood in the nodes of Equisetum are cited, though no reference is made to the cambium in the young cone as reported by J]FFREY.24 The other cases of secondary growth include Psilotum, Selaginella spinulosa, and several species of Isoetes, especially I. hystrix, which may show a cambium outside the vascular cylinder.-M. A.

The Cell Wall

Poliovirus RNA replicative complexes are associated with cytoplasmic membranous structures that accumulate during viral infection. These membranes were immunoisolated by using a monoclonal antibody against the viral nonstructural protein 2C. Biochemical analysis of the isolated membranes revealed that several organelles of the host cell (lysosomes, trans-Golgi stack and trans-Golgi network, and endoplasmic reticulum) contributed to the virus-induced membranous structures. Electron microscopy of infected cells preserved by high-pressure freezing revealed that the virus-induced membranes contain double lipid bilayers that surround apparently cytosolic material. Immunolabeling experiments showed that poliovirus proteins 2C and 3D were localized to the same membranes as the cellular markers tested. The morphological and biochemical data are consistent with the hypothesis that autophagy or a similar host process is involved in the formation of the poliovirus-induced membranes.

Cellular origin and ultrastructure of membranes induced during poliovirus infection

Publisher Summary This chapter discusses the endocrine cells of the gastric mucosa. On ultrastructural and histochemical grounds, non-enterochromaffin (EC) endocrine cells of the gastrointestinal mucosa were classified as four or six independent cell types. Six distinct types of endocrine cells were added to the well-known EC cells. Staining patterns in light and electron microscopy amine histochemistry, and/or immunohistochemistry confirm the existence of this manifold population of endocrine cells. So far, biochemical and functional studies support the existence of four endocrine products, namely, 5-hydroxytryptamine (5HT), gastrin, histamine, and gastro glucagon. Thus, based on morphological evidence, more hormones than those presently reported are to be expected from the gastric mucosa. The interaction between endocrine cells and stimuli coming from the lumen or from blood and the nervous system; both the hypothesis of a direct interaction of luminal stimuli with the endocrine cell and a more complex mechanism involves specialized receptors and local or long central reflexes must be considered. The close dependence of most digestive functions on gastrointestinal hormones, the behavior of gastrointestinal endocrine cells in some digestive diseases associated with severe functional derangements such as peptic ulcer, malabsorption, pancreatitis, and the sequelae of surgical procedures affecting the alimentary canal—should be extensively investigated.

Endocrine Cells of the Gastric Mucosa

The role of cytoplasmic membranes in poliovirus biosynthesis.

Cell walls were prepared from the yeastlike and mycelial phases (YP and MP) of Histoplasma capsulatum and from Saccharomyces cerevisiae by mechanical disruption and washing Lipids were extracted with methanol-ether, chloroform, and acidified methanol:ether; a final extraction was made with ethylenediamine The lipid contents of H capsulatum YP and MP walls were about the same Qualitative and quantitative analyses were made of the products obtained from treatment of the cell walls, or fractions from them, with weak acid or with enzymatic preparations containing glucanase and chitinase activities YP walls contained much larger quantities of chitin and smaller quantities of mannose and amino acids than the MP walls H capsulatum MP was shown to resemble S cerevisiae by low chitin content and by the presence of a mannose polymer, soluble in ethylenediamine and water H capsulatum MP chitin appeared to be intimately associated with glucose in the wall, since enzymatic hydrolysis of the residue after mild acid hydrolysis of cell walls or fractions from them resulted in the release of glucose and acetylglucosamine; only acetylglucosamine was released from YP walls with such treatment By electron microscopic observations, the unextracted MP cell walls were much thinner than the YP, and neither wall appeared laminated Images

Comparative study of the cell walls of the yeastlike and mycelial phases of Histoplasma capsulatum.

Primary neoplasms of peripheral nerves are usually benign. The tumors have been found in patients in all parts of the world. Generally the patient has a single tumor. A striking difference in the character of peripheral nerve tumors can be found in some of the patients with the genetically determined disorder neurofibromatosis; such patients can have numerous peripheral nerve tumors, bizarre disfiguring tumors, and a greatly increased risk for malignant peripheral nerve tumors when compared to patients without the genetic disorder. Peripheral nerve neoplasms are almost always tumors derived from the nerve sheath cells, not from neoplastic neurons.'.' The exception is the neuroblastoma-ganglioneuroma-pheochromocytoma group of tumors generally found on autonomic nerves in the trunk, not in the extremities. At the end of the description of each tumor a comment indicates how the presence of neurofibromatosis modifies the behavior of the tumor. The nerve sheath tumors can be classified in four general groups: (1) schwannoma, (2) neurofibronia, (3) plexiform neurofibroma, and (4) malignant schwannoma.

Pathology of Nerve Sheath Tumors

Light and electron microscopic studies were done on a carcinoid-islet cell tumor of the duodenum and 8 carcinoid tumors of the ileum which were surgically excised from a patient with achalasia and a duodenal ulcer. By light microscopy, the duodenal tumor resembled both an islet cell tumor and a carcinoid of the type found in tissues of foregut origin; the ileal tumors had the typical characteristics of carcinoids of midgut origin. On electron microscopy, some cells of the duodenal tumor contained small round granules, which resemble the delta cell granules of the normal islets of Langerhans and the granules present in gastric carcinoid tumors. Other cells in the duodenal tumor contained large granules of low electron density. The ileal tumors contained polymorphic elongated secretory granules that were believed to contain serotonin. The association of this duodenal tumor, which had morphological characteristics of both a carcinoid and an islet cell tumor, with multiple carcinoids of the ileum and with a duodenal ulcer can be interpreted as giving further support to the concept that such duodenal tumors are related both to carcinoid and islet cell tumors.

Carcinoid-islet cell tumor of the duodenum and associated multiple carcinoid tumors of the ileum. An electron microscopic study.

Cytoplasmic membrane-bound vesicles in echovirus 12-infected cells.

This paper reports the occurrence of a band of desmosome-like complexes between schwannian loops near the nodes of Ranvier in the myelin sheath of the sciatic nerves of rats. The complexes are characterized by focal widening of the space between adjacent loops and a conspicuous density of the subjacent cytoplasm. These complexes are arranged back-to-back in a row thereby forming a band-like structure. In serial and step-section reconstructions it appears that one such band is present on either side of each nodal gap. Although the function of these complexes is unknown, it is suggested that they may serve to bond together adjacent loops of the Schwann sheath near the point where the myelin sheath is interrupted at the node of Ranvier.

James C. Harkin

Papers

Comparative study of the cell walls of the yeastlike and mycelial phases of Histoplasma capsulatum.

Pathology of Nerve Sheath Tumors

Carcinoid-islet cell tumor of the duodenum and associated multiple carcinoid tumors of the ileum. An electron microscopic study.

Cytoplasmic membrane-bound vesicles in echovirus 12-infected cells.

A series of desmosomal attachments in the schwann sheath of myelinated mammalian nerves