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At least 1,297 records · Page 72Linked to original sources
PubMed1985

Unusual structural features and assembly of gap and pleated septate junctions in embryonic cockroach CNS.

Junctional assembly in the developing CNS in cockroach embryos has been studied during the last half of neurogenesis. Atypical linear tracts of gap junctions are found to develop between attenuated cytoplasmic glial cell processes and their overlying perineurial cells during the last third of development. During both perineurial and glial gap-junctional formation, 13 nm E face (EF) intramembrane particles (IMPs), such as are characteristic of arthropod gap junctions, are seen initially as free IMPs; these then become arranged in loose irregular clusters or alignments and finally are aggregated in plaques. P face ridges (or EF grooves), typical of tight junctions, are found on the same perineurial membrane face as assembling gap-junctional PF pits (or EF particles). Pleated separate junctions also develop between adjacent perineurial processes during the last third of embryogenesis; these form by the apparent migration of individual 8 nm PF IMPs into meandering rows, which then become aligned in numerous orderly parallel stacks. Although all these junctions occur on the same perineurial membrane face, the IMPs that form the different junctional types never appear to be confused during junctional assembly. The cues to signal the advent of these precise patterns, however, are unknown.

Animals↗
PubMed1989

Human macrophage-mediated cytotoxicity of Schistosoma mansoni. Functional and structural features of the effector cells.

Human monocytes were purified from peripheral blood and cultured in vitro on hydrophobic membranes. Such cells developed into mature tissue-type macrophages after approximately 1 week in culture. During this maturation period the macrophages developed a potent cytotoxic mechanism whereby they could kill the schistosomula of Schistosoma mansoni in standard in vitro cytotoxicity assays. Cytological and ultrastructural studies of the cells grown in vitro indicated that macrophages developed many of the classical histological and ultrastructural features of 'activated' cells with ruffled plasma membranes and significant increases in rough endoplasmic reticulum and Golgi vesicles. Effective cytotoxicity depended upon contact of the effector cells and their parasite target. Further, experiments using metabolic inhibitors indicated that cytotoxicity was dependent upon protein synthesis. Initial results point to the macrophage factor being distinct from some of the better-characterised macrophage secretory products such as tumour necrosis factor, proteases and products of oxygen metabolism.

Animals↗
PubMed1995

Structural features of tracheal tube biofilm formed during prolonged mechanical ventilation.

The dissemination of tracheal tube biofilm into the mechanically ventilated lung has been proposed as a contributory factor in the pathogenesis of ventilator-associated pneumonia. In the present study, conventional light microscopy, confocal laser scanning microscopy, and scanning electron microscopy were used to examine luminal tracheal tube biofilm in tubes from ten consecutive medical intensive care patients. Biofilms also were cultured. No tube contained a predominantly microbial aggregate. Microorganisms were either dispersed throughout the biofilm or restricted to the most superficial layer. Neutrophil polymorphonuclear cells were present in all biofilms in a pattern suggesting that a layering or stratification had taken place. The distribution of neutrophils and microorganisms was consistent with a progressive accretion of respiratory secretions, rather than formation of a predominantly microbial biofilm.

Adult↗
PubMed2006

Specific structural features of syndecans and heparan sulfate chains are needed for cell signaling.

The syndecans, heparan sulfate proteoglycans, are abundant molecules associated with the cell surface and extracellular matrix and consist of a protein core to which heparan sulfate chains are covalently attached. Each of the syndecan core proteins has a short cytoplasmic domain that binds cytosolic regulatory factors. The syndecans also contain highly conserved transmembrane domains and extracellular domains for which important activities are becoming known. These protein domains locate the syndecan on cell surface sites during development and tumor formation where they interact with other receptors to regulate signaling and cytoskeletal organization. The functions of cell surface heparan sulfate proteoglycan have been centered on the role of heparan sulfate chains, located on the outer side of the cell surface, in the binding of a wide array of ligands, including extracellular matrix proteins and soluble growth factors. More recently, the core proteins of the syndecan family transmembrane proteoglycans have also been shown to be involved in cell signaling through interaction with integrins and tyrosine kinase receptors.

Animals↗
PubMed1989

A comparison of structural features of the walls of coronary arteries from 10 different species.

The intimal thickness of the coronary arteries of humans less than 20 years of age was compared with that 9 other species. It was found that humans were unique amongst the species studied in showing substantial intimal thickening at an early age. The intimal thickening was associated with defects of the internal elastic lamina (IEL), which in humans were not repaired, but which in other species were associated with an effective reduplication of the IEL. This reformed IEL appeared in other species to form a significant obstruction to the diffusion of macromolecules from the lumen into the arterial wall, but did not do so in humans. Preliminary observations also indicated that the endothelial cells were closely associated with a well-formed elastin membrane in other species, and formed a continuous inner lining for the arterial wall. In human coronary arteries with substantial intimal thickening, the endothelium was incomplete, with many bare areas.

Adolescent↗
PubMed2004

[Structural features of GR6 gene and its expression in colorectal neoplasm].

OBJECTIVE: To determine the characteristics of GR6 gene and putative GR6 protein, and to evaluate the expression of GR6 gene in colorectal cancer and normal mucosa. METHODS: Bioinformatic software and databases were applied to analyze the characteristics of GR6 gene and putative GR6 protein. Semi-quantitative RT-PCR was used to detect the expression of GR6 gene in colorectal carcinoma, adenoma and normal mucosa. RESULT: GR6 gene, encoding putative GR6 protein, consisted of 3 exons and contained 4 CpG islands by sequence analysis. It was predicted that putative GR6 protein included one protein kinase C phosphorylation site, one casein kinase II phosphorylation site, and three N-myristoylation sites. PSORT II software analysis predicted that putative GR6 protein was located in nucleus (reliability: 76.7%). At the level of mRNA, the expression of GR6 gene was high in normal mucosa, moderate in mucosa adjacent to cancer and adenoma tissue, low in colorectal carcinoma tissue. Significant differences were demonstrated between normal mucosa and adenoma (P<0.05), normal mucosa and carcinoma (P<0.01). CONCLUSION: The putative GR6 protein, encoded by GR6 gene may predictably function as an important nuclear signal transduction molecule. Decreased expression of GR6 gene may play an important role in the initiation and promotion of colorectal neoplasia.

Amino Acid Sequence↗
PubMed2003

Tax and M1 peptide/HLA-A2-specific Fabs and T cell receptors recognize nonidentical structural features on peptide/HLA-A2 complexes.

Both TCRs and Ab molecules are capable of MHC-restricted recognition of peptide/MHC complexes. However, such MHC restriction is the predominant mode of recognition by T cells, but is extremely rare for B cells. The present study asks whether the dichotomy in Ag recognition modes of T and B cells could be due to fundamental differences in the methods by which TCRs and Abs recognize peptide/MHC complexes. We have compared MHC and peptide recognition by panels of CTL lines specific for the Tax and M1 peptides presented by HLA-A2 plus Tax and M1 peptide/HLA-A2-specific human Fabs that were selected from a naive phage display library. Collectively, the results indicate both striking similarities and important differences between Fab and TCR recognition of MHC and peptide components of the Tax and M1/HLA-A2 complexes. These findings suggest that these two classes of immunoreceptors have solved the problem of specific recognition of peptide/MHC complexes by nonidentical mechanisms. This conclusion is important in part because it indicates that Ab engineering approaches could produce second-generation Ab molecules that more closely mimic TCR fine specificity. Such efforts may produce more efficacious diagnostic and therapeutic agents.

Amino Acid Substitution↗
PubMed2002

Structural features of nucleoli in blood, leukemic, lymphoma and myeloma cells.

At present, it seems clear that the nucleolus is multifunctional and represents one of the key cell organelles that participate directly or indirectly in cell resting, proliferation, differentiation and maturation states, and possibly also in programmed cell death. Thus, the morphology and cytochemistry of nucleoli may represent a very useful tool not only for the evaluation of nucleolar biosynthetic activities but also for the evaluation of various cell states under physiological, experimental and pathological conditions.

Blood Cells↗
PubMed1999

[Age-specific structural features of the nasal septum in children].

Hearing was studied in 20 and 34 patients with subclinical and initial renal failure (RF), respectively. RF was secondary to chronic glomerulonephritis, chronic pyelonephritis, renal polycystosis (29, 24 and 1 patients, respectively). Hearing function was assessed at tonal threshold, suprathreshold and speech audiometry, ultrasound investigations. It was found that one third of the patients had bilateral symmetric hearing disorder of neurosensory hypoacusis type. The affection was not severe but involved both peripheral and central compartments of the acoustic analyzer. High-frequency sound sensitivity suffered most of all. There was a rise in hearing thresholds by air and bone conductivity at frequencies 12-18 kHz. This rise was the only marker of affected acoustic analyzer in 39% of the examinees. 12% of the patients demonstrated elevated hearing thresholds combined with elevated ultrasound thresholds, low differential threshold of sound intensity and abnormal threshold adaptation.

Adolescent↗