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At least 1,783 records · Page 99Linked to original sources
PubMed2003

[Chemical behavior and ecological effects of pollutants acting on root-soil interface].

Root-soil interface is the main entrance of pollutants intruding into plant tissues and the special micro-ecosphere that can result in a series of ecological safety problems. In this review, the concept of root-soil interface is presented and it is suggested that root-soil interface behavior and effects of chemical pollutants should be grouped into two aspects as rhizosphere chemical behavior and ecological effects and root chemical behavior and ecological effects. These two aspects are theoretically discussed according to the latest research advances. Rhizosphere chemical behavior and ecological effects included rhizosphere pH environment and adsorptive behavior, rhizosphere oxidation-reduction behavior, rhizosphere chemical toxicology effects, rhizosphere microbiological effects, and rhizosphere bioenzymatic reaction etc., and root chemical behavior and ecological effects included root exudation, influence of enzymatic systems in roots, disturbance of normal physiological processes, change of cellular structure and function, and interference of structure and function of biological macromolecules. Particular attention should be paid to the significance as well as some problems of research on chemical behavior and ecological effects of pollutants acting root-soil interface in pollution ecology.

Adsorption↗
PubMedDate not supplied

New methods for assessing liver function in infants and children.

Assessment of liver function in infants and children has traditionally relied on static indices of hepatic structure, cellular integrity, or function and are often based on the release of substances from damaged tissues. There has been a rapid development of dynamic tests based on the measurement of substances metabolized or cleared from blood by the liver. These tests, which have been touted to offer a more precise quantitative estimation of hepatic functional capacity, include the measurement of serum bile acids and the hepatic metabolism of xenobiotic compounds such as caffeine and lidocaine. Serum bile acid measurements appear to be reliable indicators of enterohepatic circulation and may be useful in screening for liver disease. It has been observed that caffeine metabolism is decreased in patients with various forms of liver disease in correlating with disease status. Caffeine has the advantage of being well tolerated when administered orally; the saliva level parallels the serum concentration, making a non-invasive test feasible. Lidocaine is metabolized by oxidative de-ethylation to monoethylglycinexylide (MEGX); analysis of MEGX by common laboratory instrumentation makes rapid evaluation of liver function possible. The MEGX values correlated were with pretransplant liver disease assessment. These tests are currently being evaluated at other centers and, if the initial studies are repeated, they offer the hope for reliable dynamic tests of hepatic function.

Adult↗
PubMedDate not supplied

[Highest level of division in classification of organisms. 2. Archaebacteria, eubacteria and eukaryotes].

In three-domain system of organic world archaebacteria are considered as the third form of life alongside with eubacteria and eukaryotes. The author gives brief characteristics of all three groups with special focus on such diagnostic attributes as: plasmatic membrane and cellular wall, flagella, protein transcription, replication, topoisomerases, transcription, translation, glycosylation, chaperons and chaperonins, proteasomes and exosomes, histones, ATP-ases. The three-domain system has been proposed by several scientists but principal ideas were put by C. Woese. The systematics according Woese should reflect contemporary level of our knowledge of organisms. In the historical plan it once had to refuse dividing the organic world into plants and animals but accept the division into prokaryotes and eukaryotes. The science however goes further and turns now to the new level of generalizations based on the molecular aspects of cellular structures and processes. From this point of view, both plants and animals are uniform. As to prokaryotes they appeared to be non-monolithic group because of essentially different transcriptional and translational mechanisms. Therefore the detachment of archaebacteria as an independent group was the important step in the development of systematics. At the same time the three-domain system of organisms is typological and requires correction according to data on phylogenetic relatedness of these groups.

Archaea↗
PubMed1977

Carbon tetrachloride-induced changes in mixed function oxidases and microsomal cytochromes in the rat lung.

The effects of a single exposure, by gastric intubation or inhalation, to carbon tetrachloride (CCL4) on rat lungs were assessed. By 1 to 7 days, focal areas of alveolar collapse, septal edema, and modification of type II pneumonocytes were observed. By 24 hours after exposure to the toxin, there were no identifiable changes in surfactant levels or distribution. Microsomes obtained from the lungs and prepared for analysis revealed marked decreases in cytochrome P-450 content and P-450-related N-demethylation of dimethylaniline. Only a transient reduction of cytochrome b5 occurred, with a rebound exceeding control values during the period of pulmonary healing. Whether the lung acted as an excretory route (following intubation) or as an absorption path (after inhalation) made little difference. Carbon tetrachloride had no effect on in vitro microsome composition and function unless supplemented with a reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) generating system. Under these circumstances, there was a reduction in both cytochromes b5 and P-450. Our data indicate that a considerable chemical modification of the pulmonary tissues had taken place, with no accompanying easily recognized changes in cellular structure. Furthermore, evidence for the in vitro destruction of pulmonary microsomal cytochromes P-450 and b5, unrelated to peroxidation, is indicated by these findings.

Administration, Oral↗
PubMed1992

Carbohydrates of the cell surface: molecular aspects of glycosyltransferases and their genes.

With the development of monospecific antibodies to transferase proteins as well as cDNA probes to cloned transferase genes, the study of glycosylation and its regulatory mechanisms holds great promise for the future. Here we provide a brief overview of the present knowledge of glycosyltransferases, their primary structure, cellular topography, regulation, and the basis of the genetic polymorphisms as revealed by blood groups.

Animals↗
PubMed2004

Early foetal development of the articular disc in the human temporomandibular joint.

In foetuses of 9 and 10 weeks the articular disc presents a more cellular structure with bands of connective tissue fibres. It is connected with the articular capsule and lateral pterygoid muscle. During weeks 11 and 12 there is an increase in collagenous fibres and fusiform cells are located mainly close to the surface of the disc.

Female↗
PubMed1992

Autoradiographic localization in polychaete embryos of tritiated mesulergine, a selective antagonist of serotonin receptors that inhibits early polychaete development.

Developing embryos of the polychaete Ophryotrochal labronica were exposed to tritiated mesulergine, a selective antagonist of the serotonin receptors 5-HT1c and 5-HT2, that also has significant affinity to dopamine D-2 sites, and the labeling was analyzed by autoradiography. Already at the earliest developmental stages (1-4 cells), numerous silver grains visualizing 3H-mesulergine binding sites and possibly also serotonin receptors were recorded over the cytoplasm, mostly in association with decomposing yolk granules, but few grains were detected over the nuclear region. In advanced pregastrular embryos (3 days) the number of silver grains was greatly increased over nuclei, cell borders and non-yolk cytoplasmic elements, notably in the animal half of the embryos. For newly gastrulated embryos (4 days), more than 90% of the grains appeared over non-yolk cellular structures. Abundant access to serotonin receptors is probably a fundamental condition not only for gastrulation but also for the high mitotic activity of the cleavage period. An indication hereof is the observation that exposure of cleaving polychaete eggs/embryos to unlabeled mesulergine inhibited cytokinesis and chromosome movements, whereas spindle formation and chromosome duplication were unaffected.

Animals↗
PubMed2004

Spectral and lifetime fluorescence imaging microscopies: new modalities of multiphoton microscopy applied to tissue or cell engineering.

Spectral and multiphoton imaging is the preferred approach for non-invasive study allowing deeper penetration to image molecular processes in living cells. But currently available fluorescence microscopic techniques based on fluorescence intensity, such as confocal or multiphoton excitation, cannot provide detailed quantitative information about the dynamic of complex cellular structure (molecular interaction). Due to the variation of the probe concentration, photostability, cross-talking, its effects cannot be distinguished in simple intensity images. Therefore, Time Resolved fluorescence image is required to investigate molecular interactions in biological systems. Fluorescence lifetimes are generally absolute, sensitive to environment, independent of the concentration of the probe and allow the use of probes with overlapping spectra but that not have the same fluorescence lifetime. In this work, we present the possibilities that are opened up by Fluorescence Lifetime Imaging Microscopy, firstly to collect images based on fluorescence lifetime contrast of GFP variants used as a reporter of gene expression in chondrocytes and secondly, to measure molecular proximity in erythrocyte (glycophorin/membrane) by Fluorescence Resonance Energy Transfer (FLIM-FRET).

Erythrocytes↗
PubMed2004

[Cellular ultrastructural changes of bone marrow of patients with hemorrhagic fever with renal syndrome].

BACKGROUND: To observe cytopathogenic effect of Hantaan virus (HV) on cultured human bone marrow cells. METHODS: Light and transmission electron microscopy and direct immunofluorescent technique were applied to study cellular structure especially ultrastructural changes of bone marrow cells from patients with Hantaan virus infection. Bone marrow cells of one healthy volunteer were also studied as control. RESULTS: The antigen of HV was found in bone marrow cells of 20 of 27 HFRS patients by the aid of direct immunofluorescent technique. It was found that the granulocytes had the highest percentage of HV antigen positive cells (76%), followed by monocytes (65%), lymphocytes (40%), megakaryocytes (20%) and the lowest was found in erythrocytes (3.7%). The injury of cell membrane after infection with HV was significantly more severe than that in the control group under the light and electron microscopy. CONCLUSION: This study demonstrated that HV could attack human bone marrow cells and cause cytopathogenic effect on them.

Adult↗
PubMed2004

[Differentiation of the colon endocrine cells in mucosal epithelium of humans and some vertebrate animals].

By electron microscopy, the mucosal epithelium of a distal part of the intestine of humans and other vertebrates (Rana temporaria, Lacerta vivipara, Columba livia, rabbit, rat, pig, cow) was examined. On the basis of the variety of cellular structure and the level of specialization of the involved elements a common regularity of ways of differentiation of endocrine cells was revealed. The updating of endocrine cells basically occurs as a result of differentiation of cambial cells through intermediate pre-enteroendocrine forms. Reorganization of exocrine epithelial cells is accomplished through "mixed" exo-endocrine cells. At the lower vertebrate animals the "mixed" cells are met much more frequently than in mammals, including man. In humans the greatest quantity of these cells is observed in the intra-uterine period of development and in cases of pathology. Ways of cytogenesis in endocrine cells are differently manfested in the course of ontogenesis and under broken ability to live.

Animals↗
PubMedDate not supplied

Regulation of connective tissue homeostasis in the skin by mechanical forces.

Mechanical forces come in a variety of different forms and act on many more tissues than the obvious vascular and musculo-skeletal systems. Next to soluble mediators, they have caught our attention as potent regulatory parameters in modifying the metabolism and phenotype of cells. This paper concentrates on the response of the skin to tensile forces and describes the adaptive phenotype of fibroblasts residing in the dermal connective tissue. Work from a number of different groups suggests that tension induces in these cells many biological properties which have been found in pathological conditions, e.g. in fibrotic skin lesions. Mechanical tension can therefore be regarded as an additional important regulatory parameter, which we would like to better understand with respect to mechanosensing cellular structures and specific or shared signaling pathways.

Biomechanical Phenomena↗
PubMed2004

[Morpho-functional changes of splenic autotransplants at the different time intervals after the operation].

This investigation was aimed at the study of splenic autotransplant cytoarchitectonics and cellular structures functional activity 3-60 days after the operation. The studies were carried out in 70 albino male rats including intact animals (n-10) and rats subjected to splenectomy and subsequent spleen heterotopic autotransplantation (n-60). Cryostat sections of transplants were processed for Falc and Cross luminescent-histochemical methods and were stained with hematoxylin and eosin. Biogenic amines content was measured using LUMAM-4 microscope with FMEL-1A spectrofluorimetric device. The number of luminescent cells in periarterial T-dependent zone was found to increase significantly after 7 days, while the unchanged lymphoid nodules were found in the zone of unaltered tissues. At day 15 "intrafollicular" luminescent granulocytes appeared in the newly formed lymphoid nodules. At days 15 to 45 the increased content of biogenic amines was detected in the "intrafollicular" cells, while the significant rise in the amount of amines was seen in the lymphocytes of nodule T-independent zone. It is suggested that the presence of intact nodules in transplant peripheral zone together with an increase in cell numbers in T-dependent zone, are the key events in the development of immune-correction effect of the transplanted spleen during the first two weeks after the operation.

Animals↗
PubMed2004

Role of proteases in the pathophysiology of cardiac disease.

Cardiovascular disease is a major cause of death and thus a great deal of effort has been made in salvaging the diseased myocardium. Although various factors have been identified as possible causes of different cardiac diseases such as heart failure and ischemic heart disease, there is a real need to elucidate their role for the better understanding of the cardiac disease pathology and formulation of strategies for developing newer therapeutic interventions. In view of the intimate involvement of different types of proteases in maintaining cellular structure, the role of proteases in various cardiac diseases has become the focus of recent research. Proteases are present in the cytosol as well as are localized in a number of subcellular organelles in the cell. These are known to use extracellular matrix, cytoskeletal, sarcolemmal, sarcoplasmic reticular, mitochondrial and myofibrillar proteins as substrates. Work from different laboratories using a wide variety of techniques has shown that the activation of proteases causes alterations of a number of specific proteins leading to subcellular remodeling and cardiac dysfunction. Inhibition of protease action by different drugs and agents, therefore, has a clinical relevance and is expected to form a part of new treatment paradigm for improving heart function. This review examines the biochemistry and localization of some of the proteases in the cardiac tissue in addition to identification of the sites of action of some protease inhibitors.

Animals↗
PubMed2004

Neuronal pathway finding: from neurons to initial neural networks.

Neuronal pathway finding is crucial for structured cellular organization and development of neural circuits within the nervous system. Neuronal pathway finding within the visual system has been extensively studied and therefore is used as a model to review existing knowledge regarding concepts of this developmental process. General principles of neuron pathway finding throughout the nervous system exist. Comprehension of these concepts guides neuroscience nurses in gaining an understanding of the developmental course of action, the implications of different anomalies, as well as the theoretical basis and nursing implications of some provocative new therapies being proposed to treat neurodegenerative diseases and neurologic injuries. These therapies have limitations in light of current ethical, developmental, and delivery modes and what is known about the development of neuronal pathways.

Afferent Pathways↗
PubMedDate not supplied

[Effect of aluminum and iron on lipid metabolism in aquatic invertebrates].

Methods of thin-layer, gas-liquid, and liquid chromatography were applied to the study of the effect of various concentrations of aluminum and iron salts on the contents of phospholipids, cholesterol, and fatty acids in the aquatic invertebrate Hydropsyche contubernalis L. (Trichoptera). It was found that the effect of the metals under study on lipid contents in living organisms depended on the composition of the aqueous medium and concentrations of the metals. Aluminum and iron altered the value of the cholesterol-to-phospholipid molar ratio. In the absence of lethal effects, this was indicative of attempts to switch adaptational biochemical mechanisms to stabilize cellular structures.

Aluminum Compounds↗
PubMed2005

Direct tumor damage mechanisms of photodynamic therapy.

Photodynamic therapy (PDT) is a clinically approved and rapidly developing cancer treatment regimen. It is a minimally invasive two-stage procedure that requires administration of a photosensitizing agent followed by illumination of the tumor with visible light usually generated by laser sources. A third component of PDT is molecular oxygen which is required for the most effective antitumor effects. In the presence of the latter, light of an appropriate wavelength excites the photosensitizer thereby producing cytotoxic intermediates that damage cellular structures. PDT has been approved in many countries for the treatment of lung, esophageal, bladder, skin and head and neck cancers. The antitumor effects of this treatment result from the combination of direct tumor cell photodamage, destruction of tumor vasculature and activation of an immune response. The mechanisms of the direct photodamage of tumor cells, the signaling pathways that lead to apoptosis or survival of sublethaly damaged cells, and potential novel strategies of improving the antitumor efficacy of PDT are discussed.

Animals↗
PubMed2004

Magnetic resonance imaging of mean values and anisotropy of electrical conductivity in the human brain.

The conductivity distribution in the human brain is difficult to obtain by conventional impedance tomography methods, in which currents are applied via surface electrodes. In this study, we obtained images of anisotropic conductivity in the human brain using diffusion magnetic resonance imaging (MRI). Diffusion-weighted images of the brain were acquired by a 1.5 T MRI system using an echo planar imaging sequence. Motion-probing gradients (MPGs) were applied with 25 arrayed b-factors up to 5000 s/mm2. The fast and slow diffusion components were estimated by fitting a biexponential attenuation function to the measured signals. The effective conductivities in each direction were calculated from the fast diffusion components. The mean conductivities of the cortex, the corpus callosum, and the internal capsule were 0.10 +/- 0.03 S/m, 0.12 +/- 0.02 S/m, and 0.08 +/- 0.01 S/m, respectively. Tissues with highly anisotropic cellular structures, such as the corpus callosum and the internal capsule, exhibited high anisotropy in conductivity. The anisotropy indices in the cortex, the corpus callosum, and the internal capsule were 0.07 +/- 0.03, 0.60 +/- 0.07, and 0.65 +/- 0.05, respectively.

Anisotropy↗
PubMed2005

Gastrointestinal stromal tumors. A multicenter experience.

The report presents 200 cases of gastrointestinal stromal tumors (GIST). The material originated from six diagnostic centers in Poland and was reclassified according to the current criteria. Among lesions other than GISTs, 14 were identified as smooth muscle tumors and seven as neural tumors. GISTs were located in the stomach (51-63.3% of the investigated series), small intestine (27.4-33.8%), colon (approximately 4.5%), abdominal cavity, i.e. in the peritoneum and omentum (6%), and in the retroperitoneal space (2.5%). A slight predominance of women was noted (53-56%). The age of the patients ranged between 14 and 93 years of life, with the mean age of 62.4 years. Individuals younger than 45 years of age accounted for 10% of the group. In ten patients (five of them less than 45 years of life), multiple tumors were detected, their number ranging from two to less than 20; these individuals constituted 5% of the entire series. Moderately and highly aggressive tumors predominated. In the series, when multiple tumors were excluded, a total of 24 epithelioid GISTs (12%) were observed; of this number, 13 were situated in the stomach, six--in the small intestine, two--in the abdominal cavity and another two in the retroperitoneal space. Synchronic tumors observed in patients with GISTs were seen in seven patients, including an adenocarcinoma of the colon, two adenocarcinomas of the stomach, a carcinoid tumor of the small intestine, a pheochromocytoma of the retroperitoneal space, an anaplastic lymphoma and a disseminated squamous cell carcinoma. In immunohistochemical reactions (CD117, CD34, SMA, S-100, DES), attention was focused on the immunoreactivity of small GISTs, below 2 cm in size, and of multiple tumors. Immunohistochemical reactions were equally differentiated as to their presence and intensity in small tumors and in highly aggressive lesions above 5-10 cm in size. In multiple GISTs, immunohistochemical tests strongly indicated the heterogeneity of neoplastic cells, which, nevertheless, showed no consistent association with the location of the tumor, its aggressiveness, cellular structure or a tendency to form multiple foci.

Adolescent↗