Spongy Matrix Research Articles

Ameloblastoma of the mandible with cervical lymph node metastasis

Ameloblastoma is an uncommon, slowgrowing, odontogenic epithelial tumor. This lesion is thought to originate from precursor cells of the tooth follicle, and invades the spongy trabecular matrix of the mandible and maxilla. It extends with finger-like projections, making complete resection difficult with curettage or conservative local excision1 Although histologically benign, the tumor may invade local structures; metastases to regional nodes or distant sites such as lung, liver, and skin, although reported, are rare. Because of its invasive characteristics, this tumor is capable of causing significant disfigurement and morbidity. On rare occasions individuals succumb to this disease, more often when it occurs in the maxilla. There have been nine reported cases of ameloblastoma with cervical lymph node metastasis.2*3 This case serves to emphasize the potentially recurrent, aggressive nature of this tumor, despite seemingly adequate resection.

Solution of hollow fibre bioreactor design equations for zero-order limit of Michaelis-Menten kinetics

The mass balance equations for hollow fibre bioreactors have been solved for the zero-order limit of the Michaelis-Menten kinetics. As in the case of first-order reactions, the membrane and spongy matrix equations can be decoupled from the overall set of equations. For the case of the substrate remaining constant everywhere in the reactor a solution in terms of hypergeometric series is possible. For the substrate exhaustion case the extinction radius is a non-linear function of the system parameters and thus the equations have to be solved by numerical methods.

The solution of hollow fiber bioreactor design equations.

A methodology for simplifying the solution procedure for hollow fiber bioreactor design equations has been described. Such a procedure facilitates decoupling of membrane and spongy matrix equations from the tube side equations. The equivalence between the reduced equations and the hemodialyzer problem has been explicitly obtained.

Topography of methanogenic subpopulations in a microbial consortium adapting to thermophilic conditions

Summary: The microanatomy of a granular, methanogenic, microbial consortium (granule) was investigated by applying histochemical chemical techniques and light microscopy. The granules were obtained from a full-scale, mesophilic, upflow anaerobic-sludge blanket (UASB) bioreactor and were inoculated into laboratory-scale counterparts with a defined Substrate in which they were maintained for several weeks before shifting to thermophilic conditions. Samples for analysis were collected from the original inoculum, and from the laboratory-scale bioreactors before and after the temperature shift. Four months after this shift, the basic architectural plan of the granules was found to comprise a core or medulla, and a peripheral zone or cortex bounded by denser layers, and a spongy matrix formed by microbes and intercellular material. Also, five methanogenic subpopulations known to occur in these 4-month thermophilic granules were mapped to elucidate their spatial arrangement using immunofluorescence with antibody probes of predefined specificity spectra on histologic thin sections. Each subpopulation showed a distinctive distribution pattern; e.g. elongated surface and inner colonies for the methanogen antigenically related to Methanobacterium thermoautotrophicum ΔH, packets and cellular cords for the methanosarcina related to Methanosarcina thermophila TM1, bundles for Methanothrix rods, and dense or sparse lawns for the methanogens antigenically related to Methanobrevibacter arboriphilus AZ and Methanobrevibacter smithii ALI, respectively. These features were absent from, or much less developed in, the original inoculum granules, and before the temperature shift or even 1 week thereafter. All granules showed the same basic architecture involving a cortex and a medulla, but the inner texture of the mesophilic granules was considerably more compact than that of the 4-month thermophilic granules. Thus, the topography of methanogenic subpopulations and some structural details of the 4-month thermophilic granules Seem to be the result of adaptation to enrivonmental factors such as temperature, the same way as the array of methanogenic species and their numbers were found to be in previous work.

The contribution of flour components to the structure of injera, an Ethiopian fermented bread made from tef ( Eragrostis tef)

Injera, a pancake-like fermented bread prepared from white or red tef ( Eragrostis tef ) flour, is the traditional staple food of Ethiopia. The fate of the major components of the bran and endosperm during the two-stage fermentation and baking has been examined by light and electron microscopy. Angular starch granules released from compound grains during milling showed a range of erosion effects typical of enzymic degradation during fermentation. The appearances of bran and embryo fragments, cell walls and protein bodies were unaffected by fermentation or baking. Microorganisms, the natural contaminants of tef grains, produced strands of fibrillar material during fermentation that bound the flour particles together. Apart from the presence of polyphenolic material in the testa cells of red tef, no structural differences were observed between red and white grain during the preparation of Injera, The portion of dough that was thinned, boiled and returned to the mixture for the second fermentation period contained swollen gelatinised starch. During cooking, the starch within the injera was totally gelatinised to form a steam-leavened, spongy starch matrix, in which fragments of bran and embryo, micro-organisms and organelles were embedded. The protein bodies played no role in the formation of the matrix-gas bubble interface.

Composition and ultrastructure of the byssus of Mytilus edulis.

Three regions of the byssus of the marine mussel Mytilus edulis L. are distinct in structural organization at the macroscopic and microscopic level and in amino acid composition. The threads that emanate from the stem at the base of the foot are divided into two regions. The proximal, elastic region has a crimped, densely staining cortex enclosing an interior matrix of spiral fibers, and its amino acid composition reflects protein heterogeneity. The more distal, rigid region has a straight, tubular cortex surrounding an inner matrix of linearly arranged bundles of fibrils and has a composition approximating pure collagen. The plaque, or disc-shaped portion, which mediates attachment to various substrates, is distinguished by a surface matrix of collagen-like fibers similar to those of the thread region and anchored on an inner spongy matrix. Compositional evidence exists for a collagenous component, a catechol-rich protein, and at least one other accessory protein in the plaque.

Transplant glomerulopathy: Evolution of morphologically distinct changes

AbstractTransplant glomerulopathy: Evolution of morphologically distinct changes. The study was undertaken to redefine morphological appearance and clinical implications of the diagnosis of transplant glomerulopathy (TGP). Fifty-seven renal transplant biopsy specimens from thirty patients with the diagnosis of TGP were evaluated. Multiple repeat biopsies in several cases enabled us to follow the pattern of the evolution of the changes. Transplant dysfunction manifested itself 8 days to 13 years post-transplantation by proteinuria and/or elevated creatinine level. The earliest recognizable morphological change was the swelling of endothelial and mesangial cells. This stage was called evolving TGP. The intermediate stage was characterized by enlarged glomeruli with lobular simplification, spongy matrix, and glomerular basement membrane (GBM) deformities. The advanced stage of TGP showed pronounced GBM changes (reduplication, interposition). These light microscopic changes were associated with vascular rejection. Immunofluorescence showed significant glomerular deposition of IgM (83% of biopsies) and fibrinogen (66%). Electron microscopy at an early stage showed subendothelial widening with cellular debris and focal endothelial damage with fibrin deposition. In the advanced stage, complex GBM changes developed as a reparative response to the capillary wall injury. Effacement of foot processes was a constant finding at all stages. In follow-up, twenty-three allografts failed (77%), five patients are stable, and two died due to other causes. TGP has specific morphology with an attendant poor long-term prognosis for the allograft.Glomérulopathie du transplant: Evolution de changements morphologiquement distincts. Cette étude a été entreprise pour redéfinir l'aspect morphologique et les implications cliniques du diagnostic de glomérulopathie du transplant (TGP). Cinquante-sept spécimens biopsiques de transplants rénaux provenant de trente malades porteurs du diagnostic de TGP ont été évaluées. Des biopsies répétées de multiples fois dans plusieurs cas nous ont permis de suivre l'aspect évolutif des modifications. Le dysfonctionnement du transplant se manifestait lui-même de 8 jours à 13 ans après la transplantation par une protéinurie et/ou un niveau de créatinine élevé. La modification morphologique reconnaissable le plus précocement était un gonflement des cellules endothéliales et mésangiales. Ce stade était appelé TGP en apparition. Le stade intermédiaire était caractérisé par des glomérules de taille accrue, avec une simplification lobulaire, une matrice spongieuse, et des déformations de la membrane basale glomérulaire (GBM). Le stade avancé de TGP présentait des modifications prononcées de la GBM (déboublement, interposition). Ces modifications en microscopie optique étaient associées à un rejet vasculaire. L'immunofluorescence révélait des dépôts glomérulaires significatifs d'IgM (83% des biopsies) et de fibrinogène (66%). La microscopie électronique à un stade précoce révélait un épaississement sous-endothélial avec des débris cellulaires et des lésions endothéliales focales avec dépôts de fibrine. Au stade avancé, des modifications complexes de la GBM se développaient à titre de réponse réparative aux altérations de la paroi capillaire. L'effacement des pédicelles était un fait constant à tous les stades. Lors du suivi, vingt trois allogreffes ont échoué (77%), cinq malades sont stables, et deux sont décédées d'autres causes. TGP a une morphologie spécifique avec un pronostic associé à long terme défavorable pour l'allogreffe.

Distribution of Spongodiscid-Type Radiolarians In Modern Sediments: ABSTRACT

Spongodiscid-type radiolarians have a spongy appearance (foamy or loosely organized skeleton), are discoidal in shape and may or may not have flat extensions (arms) from the central region of the skeleton. They are common in modern sediments, are cosmopolitan in distribution, and range throughout the Phanerozoic. Their significance in modern sediments has not been fully investigated, especially with respect to their ecology. Morphologic characteristics are investigated in this study, especially the type of matrix, spines, outer covering, and internal growth, and how it relates to environmental parameters. Spongodiscid-type distributions in the present oceans are evaluated (1) by using published reports on spongodiscid-types in modern sediments and (2) by observing samples material (SEM End_Page 425------------------------------ and transmitting light microscope) from the Arctic, Bering Sea, Gulf of Mexico, Southern Atlantic, equatorial Pacific, California continental borderlands, Indian and Antarctic Oceans. Three groups of spongodiscid-type radiolarians were identified. (1) Spongotrochus glacialis group (robust spongy matrix, with or without spines, without arms) dominates the polar oceans. The diversity is low and the assemblage can inhabit the waters of the shelf as well as the slope. (2) Stylochlamydium venustum group (spongodiscid-type with distinct pores, spongy matrix, with or without spines, without arms) plus S. glacialis, dominate subarctic assemblages. (3) S. glacialis and spongodiscid-type with arms are found in the equatorial region. The diversity here is much greater than in any of the other ar as. These results are plotted on a world map comparing the distribution of recent spongodiscid-type with surface-water temperature, water temperature at depth 200 and 400 m (656 and 1,312 ft), surface salinity, surface and bottom currents and bottom topography of the world ocean. End_of_Article - Last_Page 426------------

Ultrastructural changes in Caenorhabditis elegans (nematoda) caused by toxic levels of mercury and silver

Mercury toxicity in Caenorhabditis elegans showed as lesions in esophageal muscles and intestinal cells and consisted of degradation of the cytoplasm and the formation of irregularly shaped cytosomes. Specimens intoxicated with silver showed changed cytosomes with a spongy matrix in the intestinal cells and ruffled membranes on the mitochondria of hypodermal cells. General ultrastructural responses reflecting a distress syndrome common to several heavy metals were also noted. The results are discussed with reference to the concept of using free-living nematodes to assist in the diagnosis of the causative toxic heavy metal in a complex.

Morphological Studies on Amaranthus cruentus

ABSTRACTThe morphology of Amaranthus cruentus was studied using scanning election and light microscopy. The A. cruentus seed consists of a single layer of cells which is intimately associated with the perispeim. In the region of the embryo, the seed coat is attached to the endosperm remaining in the mature seed. The major portion of endosperm caps the root. Large, thick‐walled endosperm cells contain spherical bodies embedded in a spongy matrix. The cells of the campylotropous embryo contain material which has properties typical of lipid and lipid complexes as demonstrated by hexane extraction and by staining with osmium tetroxide. Spherical cell bodies, embedded in the lipid‐containing matrix are partially digested by trypsin, thus suggesting they are proteinaceous in nature. Perisperm in the center of the seed contains starch granules in the form of amylopectin, demonstrated by iodine‐potassium iodide stain and α‐amylase digestion.

The growth of tumors in matrix cultures.

Explants of 160 human benign and malignant tumors were cultured on the matrix of human fibrin foam. This fine porous spongy matrix prepared from human fibrinogen is biologically suitable for human tissue cultures without further preparation. Tumor cultures were maintained in the culture from 3 to 21 days. Fifty-five benign tumors preserved the architecture in “mother” fragments but did not proliferate into the matrix. One hundred five malignant tumors showed various degrees of matrix invasion. In the group of 72 gastro-intestinal tract adenocarcinomas the degree of differentiation in biopsy correlated with tumor cell invasion in the matrix culture. The observations suggest that the tumors in matrix cultures express morphologic and biologic characteristics in vitro similar to those in vivo. This method may have potential usefulness in evaluation of tumors in biopsy material as a guide to prognosis and treatment.