Dissolution Of Tissue Research Articles

Inflated wings, tissue autolysis and early death in tissue inhibitor of metalloproteinases mutants of Drosophila

In vertebrates, tissue inhibitors of metalloproteinases (TIMPs) play key roles in extracellular matrix (ECM) homeostasis and growth control. Deletion of the recently cloned Timp gene of Drosophila results in a subviable phenotype. Adult flies display inflated wings similar to integrin mutants, suffer from a bloated gut and progressive dissolution of internal tissues, and die prematurely. Our results demonstrate that the Timp gene product controls selective aspects of ECM function in Drosophila, and suggest that it is involved in cell adhesion/cell signaling pathways. Hence, Drosophila Timp mutants may prove useful as a model system for a wide variety of pathological conditions related to ECM dysregulation.

Tie-2 and angiopoietin-2 expression at the fetal-maternal interface: a receptor ligand model for vascular remodelling.

The blood vessels at the fetal-maternal interface widen dramatically during pregnancy in order to increase blood flow to nourish the developing fetus. This vessel remodelling destroys normal vessel integrity and encompasses the dissolution of vessel muscle and elastic tissue. It also includes the displacement of endothelial cells by fetal trophoblasts that invade the maternal arteries of the uterus. Interaction between the endothelial cell receptor, Tie-2, and its recently discovered antagonist ligand, angiopoietin-2 (Ang-2), has been implicated in the loosening of vessel structure. Using Northern blot hybridization and RNA in-situ hybridization analysis the expression pattern of Tie-2, and Ang-2 in the placenta throughout pregnancy, was investigated. We found Ang-2 expressed in the syncytiotrophoblast during the first trimester. In addition to the expected expression of the Tie-2 receptor in both fetal and maternal endothelial cells, we observed Tie-2 expression in endovascular invasive trophoblasts. These cells of epithelial origin invade the uterine spiral arteries and acquire endothelial cell properties. The temporal- and lineage-specific pattern of expression of Tie-2 and Ang-2 suggests that this receptor-ligand pair functions during the critical phase of development of the fetal vasculature and reworking of the maternal vessels during normal placentation.

Effect of calcium hydroxide on the dissolution of soft tissue on the root canal wall

Calcium hydroxide [Ca(OH)2] paste can aid in the cleaning of a root canal because of its soft tissue-dissolving potential. In this study, we examined with a scanning electron microscope the dissolution by Ca(OH)2 paste of pulpal tissue attached to uninstrumented bovine root canal walls. Extracted bovine anterior teeth were divided into small specimens at the middle portion of the roots. The experimental groups were treated with sodium hypochlorite (NaOCl), Ca(OH)2, or a combination of Ca(OH)2 + NaOCl. The control group was given no treatment. The root canal walls were observed with a scanning electron microscope, and the amount of remaining pulp tissue was compared. The amount of debris was reduced remarkably in the groups treated with NaOCl for > 30 s, or Ca(OH)2 for 7 days. The combination of Ca(OH)2 + NaOCl was more effective than the separate treatments. The results suggest that Ca(OH)2 as a root canal medicine serves as an effective agent in removing tissue debris remaining on the root canal walls.

Microwave dissolution of plant tissue and the subsequent determination of trace lanthanide and actinide elements by inductively coupled plasma-mass spectrometry

Recently there has been much concern about the ability of plants to uptake heavy metals from their surroundings. With the development of instrumental techniques with low detection limits, such as inductively coupled plasma-mass spectrometry (ICP-MS), attention is shifting toward achieving faster and more elegant ways of oxidizing the organic material inherent in environmental samples. Closed-vessel microwave dissolution was compared with conventional methods for the determination of concentrations of cerium, samarium, europium, terbium, uranium, and thorium in a series of samples from the National Institute of Standards and Technology and from fields in Idaho. The ICP-MS technique exhibited detection limits in parts-per-trillion and linear calibration plots over three orders of magnitude for the elements under study. The results obtained by using nitric acid and hydrogen peroxide in a microwave digestion system for the analysis of reference materials showed close agreement with the accepted values. These values were compared with results obtained from dry- and wet-ashing procedures. The findings from an experiment comparing radiometric techniques for the determination of actinide elements to ICP-MS are reported.

Effect of calcium hydroxide paste dressing on uninstrumented root canal wall

Dissolution of soft tissues on the uninstrumented root canal wall by an intracanal dressing of calcium hydroxide paste was examined by scanning electron microscopy (SEM). The roots of human extracted teeth were split longitudinally into halves, and the pulp tissue was removed by forceps. Then, the halves were divided randomly into three groups. Specimens in the control group were given no treatment. Specimens of the 1-wk group were stored for 7 days in calcium hydroxide-saline paste under the condition of 100% humidity and 37 degrees C. Specimens of the 4-wk group were stored for 28 days in the same manner, but washed and replaced into new paste every week. Root canal walls of these specimens were compared under a scanning electron microscope. A layer of odontoblasts was observed in the control group, whereas it had disappeared completely in the 1- and 4-wk groups. However, the predentin remained almost intact in the 1-wk group, and although the surface was eroded, in the 4-wk group. It was found that calcium hydroxide paste dressing could dissolve the odontoblastic cell layer, but had little effect on predentin.

Determination of arsenic in plant tissue using a slurry sampling graphite furnace

Abstract Commonly used methods of arsenic (As) determination in plant material require dissolution of tissue in strong acids prior to analysis. Progress in the graphite furnace atomic absorption spectrometry (GFAAS) technique has made the determination of metals in solid samples possible. This study was undertaken to evaluate the possibility of As determination directly in ground plant tissue using GFAAS. The Perkin‐Elmer Model 4100 ZL atomic absorption spectrometer with Zeeman background correction and AS‐70 autosampler has been used for analysis. Spinach (Spinacia oleracea) and com (Zea mays L.) tissues samples containing various As levels were used as test materials. Before injection of the plant slurry into the furnace, the ultrasonic agitator was used to mix the slurry in the autosampler cup to assure uniform distribution of plant powder in the whole volume of liquid. The furnace program contained a pyrolysis step using palladium as the modifier. The GFAAS method was compared with the hydride generat...

Role of cytokines and inflammatory mediators in tissue destruction.

Colonization or emergence of microbial pathogens may result in tissue destruction by activation of one or more of five distinct host degradative pathways (matrix metalloproteinase pathway, plasminogen-dependent pathway, phagocytic pathway, PMN-serine proteinase pathway and osteoclastic bone resorption) or by direct cleavage of extracellular matrix constituents by microbial proteinases. Activation of endogenous destructive pathways may be mediated by immune responses resulting in expression of degradative cellular phenotypes among both immigrant and resident cell populations. In addition, expression of degradative phenotypes may be triggered by direct influences on host cells of microbial products (LPS, enzymes, toxins). A body of evidence suggests that each of these mechanisms involves local production of proinflammatory cytokines and growth factors. The matrix metalloproteinase pathway is centrally involved in dissolution of all unmineralized connective tissues and perhaps in resorption of bone as well. The matrix metalloproteinase family consists of nine or more genetically distinct Zn++ endopeptidases which collectively cleave all of the constituents of the extracellular matrix. Recent studies have uncovered many essential elements of a complex, but still incomplete, regulatory network that governs tissue destruction. Proinflammatory cytokines and growth factors induce signalling pathways several of which are dependent on protein kinase C and result in transient expression of the transcription factors c-jun and c-fos. Initiation of transcription of most matrix metalloproteinase genes requires binding of the transcription factor AP-1 (c-jun/c-fos) to a specific promoter sequence but attainment of maximal transcription rates is dependent on interaction with other promoter elements as well. Several matrix metalloproteinases have been detected in crevicular fluids and tissues of inflamed human gingiva as have the proinflammatory cytokines (IL-1 and TNF-alpha) which regulate their transcription. Although the mere presence of enzymes and cytokines does not necessarily impart function per se, these observations suggest that some level of spatial or temporal linkage exists between metalloproteinase/cytokine expression and gingival inflammation.

Spontaneous reaction for acid dissolution of biological tissues in closed vessels.

Spontaneous reaction for acid dissolution of biological tissues in closed vessels.

The involvement of calcium phosphates in biological mineralization and demineralization processes

Abstract

Crustacea Phyllopoda and Malacostraca: a reappraisal of cephalic and thoracic shield and fold systems and their evolutionary significance

In 1909 Caiman presented the carapace hypothesis, according to which all Crustacea possess or once possessed a carapace fold, formed from the posterior margin of the cephalon. In those Crustacea which have no such free fold but a cephalothoracic shield covering the cephalon and part or the whole of the thorax, this shield was interpreted as a carapace fold fused to the dorsum of the thorax and often overhanging its sides, for example, in lobsters and natantians. When a carapace fold or carapace shield is missing, as, for example, in Anostraca or Syncarida and behind the maxilliped segment in amphipods and isopods, this has been understood to imply that a carapace fold or shield has been lost. The carapace hypothesis has been universally accepted and has influenced the interpretation of Crustacean evolution and inter-relationships. A re-examination of numerous Crustacea, including embryos and larvae, with the application of a variety of histological standard techniques, proved that no cephalic carapace fold is formed in any malacostracan presumed to possess it, or in any notostracan, spinicaudate or laevicaudate branchiopod examined. In the Branchiopoda, when a dorsal fold is formed, it is always attached to a trunk segment. Free dorsal folds in the Malacostraca are always attached to the posterior margin of a thoracic segment, and dorsal cephalothoracic shields are never formed as a result of the fusion of a cephalic carapace fold to the dorsum of the thorax. Instead, the formation of a cephalothoracic shield in the Malacostraca is always due: (i) to the fusion of the 1st thoracic segment to the cephalon in connection with the differentiation of maxillipeds; and (ii) to the obliteration of lateral and dorsal external segment borders in the whole or part of the dorsum of the thorax apparently because of the formation of continuous and unsegmented branchiostegal folds. These folds are always continuous with those of the maxilliped segment and the cephalon. In the Anaspidacea, Amphipoda and Isopoda, which have no branchiostegal folds behind the maxilliped segment, the external segmentation is retained in all segments behind it, and the same is the case with the segments behind the cephalothoracic shield in, for example, mysids and cumaceans. The rule that the number of thoracic malacostracan segments covered by a cephalothoracic shield is identical to the number of segments contributing to the formation of branchiostegal folds has no exceptions. In the light of the failure of the carapace hypothesis, the retention of an external thoracic segmentation represents a plesiomorphic condition and the formation of an only partly segmented or an unsegmented thorax a derived one. The Syncarida, with up to eight free thoracic segments in the Palaeocaridacea and Bathynellacea, then appear to reflect an ancestral condition and are possibly not too far removed from malacostracan ancestors. This permits a new approach to eumalacostracan phylogeny and higher systematics. The reason for many misunderstandings concerning dorsal folds and shields appears to be technical. Observations leading to claims that a carapace foldsensuCaiman exists, or existed, in all Crustacea were to a large extent based on studies of wholemounts, often made after maceration in potassium hydroxyde solutions. This leads to the dissolution of soft tissues so that the dorsal integument comes to consist of only a single sheet of cuticle attached anteriorly to the cephalic region. This may easily give the false impression of representing a true carapace fold. An examination of serial sections of the intact cephalothorax reveals the true topographic inter-relationships.

The influence of soil chemistry on fine root aluminum concentrations and root dynamics in a subalpine Spodosol, Washington State, USA

The relationship between root Al concentrations and Al fractions in the soil solution was examined in a mature Abies amabilis ecosystem in the Cascade Range of Washington State. The naturally acidic soils in these ecosystems lead to high concentrations of aqueous Al in soil solutions and contribute to the biocycling of Al by the A. amabilis/T. mertensiana stand. Root concentrations of Al were very closely related to aqueous Al3+ activities, but poorly correlated with total aqueous Al concentrations. The solution Al/Ca molar ratios followed a seasonal cycle with low values during the fall and high values during the spring. Ratios remained <1 throughout the year in the Oa horizon while they varied between 2 and 14 in the E and Bhs horizons. The vertical distribution of roots and the mortality of fine roots may be linked to the soil solution Al/Ca ratio. Root cation exchange capacity ranged between 180 and 225 μ mol g-1 and the exchangeable Al fraction represented from 12–17% of the total Al content in the root. Evidence for solid-phase co-precipitates of Al with PO4 and oxalate was indicated from selective dissolution of the root tissue. Sufficient quantities of PO4 and oxalate exist in the roots to tie up 20–40% of the Al present in the roots of the Oa and E horizons, but only 9% of that present in the Bhs horizon. Species differences in the distribution of Al between the above-ground and below-ground components may be dictated by these retention processes in the fine roots.

Enzymatic and anatomical changes in abscission zone cells of apple fruits induced by Ethephon

The enhancement of fruit abscission zone formation with ethephon treatment caused an increase in soluble proteins, endo-cellulase, exo-polygalacturonase and peroxidase activities. Exo-cellulase and endo-polygalacturonase did not show any relationship with apple abscission. The separation of cells initiated in the cortex region and progressed towards vascular tissue. Cell separation in the cortex appeared to be due to dissolution of middle lamella but vascular tissues ruptured mechanically.

Development of an automated experimental setup for the study of ionic-exchange kinetics. Application to the ionic adsorption, equilibrium attainment and dissolution of apatite compounds

An ion-selective electrode and microcomputer-based experimental setup for the study of ionic-exchange kinetics between a powdered solid and the solution is described. The equipment is composed of easily available commercial devices and a data acquisition and regularization computer program is presented. The system, especially developed to investigate the ionic adsorption, equilibrium attainment and dissolution of hard mineralized tissues, provides good reliable results by taking into account the volume changes of the reacting solution and the electrode behaviour under different experimental conditions, and by avoiding carbonation of the solution. A second computer program, using the regularized data and the experimental parameters, calculates the quantities of protons consumed and calcium released in the case of equilibrium attainment and dissolution of apatite-like compounds. Finally, typical examples of ion-exchange and dissolution kinetics under constant pH of enamel and synthetic hydroxyapatite are examined.

Infection of the pearl millet (Pennisetum americanum) inflorescence by the downy mildew fungus (Sclerospora graminicola)

Different developmental stages of the inflorescence of pearl millet (Pennisetum americanum) were inoculated with zoospores of the downy mildew fungus (Sclerospora graminicola). Individual florets within a panicle were infected, with resultant malformation of any floral organs that were not fully differentiated at the time of infection. ‘Green‐ear’ symptoms resulting from hyperplasia and hypertrophy of the host tissues were accompanied by both sexual and asexual sporulation of the fungus on the malformed plant parts. No grain set occurred in affected florets, indicating that secondary inoculum was able to cause yield reductions even at late stages in the host development. Infection of differentiated stigmas led to rapid dissolution and necrosis of tissue and prevented colonization by the pathogen. This failure suggests that seeds are unlikely to be infected internally.

Comments on 'Interaction of carbon dioxide laser radiation with ocular tissues' by T.J. Bridges et al

Previous experiments by Bridges et al. (in D.B. Karlin, 1984) on the interaction of carbon dioxide laser radiation with human eye lens tissue have been repeated. Contrary to previous results, it is found that there is a threshold fluence for the vaporization of lens tissue for its phototransection. Its average value is found to be about 26 J/cm/sup 2/ for 10.6- mu m radiation. Beyond this threshold fluence, the depth of incision increases with the interaction time of the laser beam. The possibility of thermal dissolution of cataractous eye lens tissue is explored and it is shown that with the CO/sub 2/ laser this is a high-temperature (270 degrees C) process, which makes it impractical for the removal of cataracts. >

Effects of calcium hydroxide and sodium hypochlorite on the dissolution of necrotic porcine muscle tissue

The dissolving effect of the endodontic medicamentscalcium hydroxide (Ca(OH) 2 ) and sodium hypochlorite (NaOCI) on necrotic tissue was studied. Pieces of necrotic porcine muscular tissue were placed in either a 0.5% NaOCI solution (Dakin's solution), Ca(OH) 2 , mixed with water, or a NaOCI solution following pretreatment in Ca(OH) 2 for various time intervals. The tissue pieces placed in 0.5% NaOCI were not completely dissolved after 12 days. When NaOCI solution was changed every 30 min, the tissue was completely dissolved after 3 h. Pieces placed in Ca(OH) 2 exhibited a marked swelling and a jelly-like consistency. The increase in weight was maintained for 24 h, after which a decrease was noted. After 12 days, the tissue was completely dissolved. Pretreatment with Ca(OH) 2 for 30 min caused the tissue to dissolve in NaOCI within 90 min. Pieces that were pretreated for 24 h or 7 days dissolved within 60 min. As a control, tissue pieces were kept in isotonic saline solution and these were not dissolved after 12 days. Apparently, long-term treatment with Ca(OH) 2 can dissolve necrotic tissue and pretreatment with Ca(OH) 2 can enhance the tissue dissolving effect of NaOCl.

44] Human neutrophil degranulation

This chapter describes the techniques for isolating these subcellular organelles from normal, unstimulated human blood neutrophils and for measuring granule exocytosis by activated neutrophils. Neutrophils are wandering, phagocytic white blood cells that are critical to host defenses against bacterial and fungal infections. They are also the first circulating leukocytes to arrive at a site of acute inflammation. Indeed, the extravascular accumulation of these cells in tissues is a fundamental histologic hallmark of the acute inflammatory response. Inflammatory neutrophils are recognized to play a key role in mediating the dissolution and remodeling of connective tissues at sites of inflammation. Neutrophils injure or destroy connective tissue cells and digest or alter extracellular matrix proteins by at least two mechanisms, generation of toxic oxygen metabolites and secretion of proteolytic enzymes. Unlike the monocyte/macrophage family of phagocytes, neutrophils retain a very limited capacity for de novo protein synthesis once they are terminally differentiated and enter the circulation from the bone marrow.

The origin, development and regulation of osteoclasts.

AbstractOsteoclasts, the multinucleated cells primarily responsible for dissolution of bone tissue, form by fusion of precursors that circulate in the bloodstream. A variety of factors have been shown to affect the mature osteoclast and its progenitor cell, such as calcium‐regulating hormones, products of the immune system, and constituents of the arachidonic acid cascade. To date, however, the osteoclast precursor has not been identified. Furthermore, there is limited information on the factors that influence osteoclast development and regulation, reflecting in part the paucity of data on the osteoclast cell surface. Recent progress in understanding osteoclasts formation and function is discussed.

Lead fragments in tissues from wild birds: A cause of misleading analytical results

Seriously damaged eider ducks ( Somateria mollissima) and long-tailed ducks ( Clangula hyemalis) were shot in connection with an oil spill in 1974. Liver and kidney tissues were analyzed for environmental pollutants and lead analysis gave irreproducible results. By means of X-ray photographs, X-ray-dense particles could be observed in the tissues. The foreign particles were extracted by dissolution of the organ tissues in Soluene-350 (Packard Instruments Co. Inc) and then washed with toluene. The insoluble particles consisted of lead and bone splinters of varying size. The form of the former ranged from irregular fragments to dust, and arose by disruption of lead pellets upon collision with bone tissue. Birds shot with lead pellets should not be used for lead determination unless careful X-ray investigations are made prior to the chemical analysis. Determinations should be made on at least two different samples of the tissue examined.

The study of Clinostomum complanatum (Rud., 1814). V. The influences of metacercaria of Clinostomum complanatum on fish.

Microscpopically, the metacercariae of Clinostomum complanatum were encapsulated by a fibrous layer to form a cyst. The cyst wall was composed of connective tissue fibers, chiefly collagen fibers, of the fish in reaction to the infection. There were blood vessels penetrating into the cyst wall and forming a capillary network. These blood vessels might supply the nutritional requirements of the metacercaria and remove the wastes produced by the worms. The metacercaria of C. complanatum got a lot of nutrients from its host for growth and storage. The possible routes of the metacercaria of C. complanatum to get nutrients from its host may be through the digestive tract or by the direct absorption of the covering of the worm from the body fluid of the fish. The morphological feature suggested that the tegument of the metacercaria of C. complanatum possessed the tegumental absorption function. Generally, the metacercariae of C. complanatum lay quiescently in the cyst. No great harm was done to fish unless there were massive numbers. The greatest damage occurred when metacercariae had been activated and migrated out of the body wall of the fish. The process of the excystment and migration of the worms caused the congestion and hemorrhage followed by the serious tissue damage. After the excystment of the metacercaria, the fish tissues around the worm were dissolved. The result indicated that the worm might produce certain enzymes to facilitate the dissolution of fish tissues and cause the death of the fish due to the destruction of the fish body.