Cellular localization of alpha3beta1 integrin isoforms in association with myofibrillogenesis during cardiac myocyte development in culture

The cellular localization of alpha3beta1 integrin isoforms was examined in cultured neonatal myocytes at selected times during development using double immunofluorescence assays. The distribution of alpha3A subunits began as diffuse and patternless, but as the cells matured, the distribution assumed a sarcomeric banding pattern, and alpha3A appeared to be localized in costameres - sarcolemmal regions adjacent to the Z-disks. Alpha-actinin, a component of the Z-disk, was localized in the same intracellular regions. Temporal analysis of the incorporation of the alpha3A subunit and other myofibrillar proteins into sarcomeres revealed that alpha3A was integrated into sarcomeres following incorporation of alpha-actinin and myosin heavy chain (MHC) but prior to that of desmin. This suggests that alpha3A integrins are incorporated into a pre-existing myofibrillar structure, and it is unlikely that alpha3A integrins participate in the initial assembly of myofibrillar proteins. The alpha3B, beta1A and beta1D subunits were also localized in costameres, where they formed alpha3Abeta1A, alpha3Abeta1D and alpha3Bbeta1A heterodimers. The alpha3Bbeta1D heterodimer, however, was not found in cardiac myocytes. The antisera raised against the cytoplasmic domains of alpha3A, alpha3B, beta1A and beta1D caused disruption of sarcomere structure. Thus, the myofibril-extracellular matrix linkages mediated by isoforms of alpha3beta1 integrin may play a crucial role in the stabilization of myofibril assembly and in the maintenance of sarcomere structure. Co-immunoprecipitation experiments revealed that beta1A, but not beta1D, interacts with the Nck signaling protein, suggesting that Nck participates in downstream signaling triggered by beta1A and that the beta1A-mediated signaling pathway is distinct from that of beta1D.

Neoadjuvant therapy in the treatment of high risk rectal carcinoma

The management of rectal cancer remains a challenging and controversial area of surgical oncology. The spectre of local recurrence, with its' poor prognostic and palliative outcomes, is known to be highly dependent on operative technique and to vary widely between surgeons. The roles of radiotherapy and chemotherapy have been the subject of trials for 30 years and yet no consensus on treatment exists. In this review article we will summarise the evolution of radiotherapy and chemoradiation in the treatment of rectal cancer and evaluate the evidence available for the use of "neoadjuvant" chemoradiation. In particular, the role of adjuvant therapies in the setting of total mesorectal excision will be discussed.

Exploring the dynamic information content of a protein NMR structure: comparison of a molecular dynamics simulation with the NMR and X-ray structures of Escherichia coli ribonuclease HI

The multiconformer nature of solution nuclear magnetic resonance (NMR) structures of proteins results from the effects of intramolecular dynamics, spin diffusion and an uneven distribution of structural restraints throughout the molecule. A delineation of the former from the latter two contributions is attempted in this work for an ensemble of 15 NMR structures of the protein Escherichia coli ribonuclease HI (RNase HI). Exploration of the dynamic information content of the NMR ensemble is carried out through correlation with data from two crystal structures and a 1.7-ns molecular dynamics (MD) trajectory of RNase HI in explicit solvent. Assessment of the consistency of the crystal and mean MD structures with nuclear Overhauser effect (NOE) data showed that the NMR ensemble is overall more compatible with the high-resolution (1.48 A) crystal structure than with either the lower-resolution (2.05 A) crystal structure or the MD simulation. Furthermore, the NMR ensemble is found to span more conformational space than the MD simulation for both the backbone and the sidechains of RNase HI. Nonetheless, the backbone conformational variability of both the NMR ensemble and the simulation is especially consistent with NMR relaxation measurements of two loop regions that are putative sites of substrate recognition. Plausible side-chain dynamic information is extracted from the NMR ensemble on the basis of (i) rotamericity and syn-pentane character of variable torsion angles, (ii) comparison of the magnitude of atomic mean-square fluctuations (msf) with those deduced from crystallographic thermal factors, and (iii) comparison of torsion angle conformational behavior in the NMR ensemble and the simulation. Several heterogeneous torsion angles, while adopting non-rotameric/syn-pentane conformations in the NMR ensemble, exist in a unique conformation in the simulation and display low X-ray thermal factors. These torsions are identified as sites whose variability is likely to be an artifact of the NMR structure determination procedure. A number of other torsions show a close correspondence between the conformations sampled in the NMR and MD ensembles, as well as significant correlations among crystallographic thermal factors and atomic msf calculated from the NMR ensemble and the simulation. These results indicate that a significant amount of dynamic information is contained in the NMR ensemble. The relevance of the present findings for the biological function of RNase HI, protein recognition studies, and previous investigations of the motional content of protein NMR structures are discussed.

Effect of eradication of Helicobacter pylori on the benign gastric ulcer recurrence--a 24 month follow-up study

OBJECTIVES

To evaluate the effect of eradication of Helicobacter pylori (H. pylori) on the recurrence of benign gastric ulcer (BGU) in the patients with BGU.

METHODS

This study was performed for 40 H. pylori-positive BGU patients cured of BGU and H. pylori eradicated, and for 25 H. pylori-positive patients (non-eradicated group) who were not treated with H. pylori eradication regimen or H. pylori was not eradicated. Four different methods--CLOtest, microscopy of Gram stained mucosal smear, culture and histology of modified Giemsa staining--were taken for identifying colonization of H. pylori before treatment, and 4 weeks after completion of triple therapy. For the control group in which triple therapy was not tried, follow-up gastroscopy was done to confirm the healing of the ulcer. To detect BGU recurrence, the gastroscopy was performed at 6, 12, 18, and 24 months after therapy.

RESULTS

In the non-eradicated group, the BGU recurrence rate was 16% within 6 months, 40% within 1 year, 56% within 18 months and 60% within 2 years. The respective recurrence rates in the 40 patients in whom the bacteria had been eradicated were 0%, 7.5%, 10% and 10% (4 patients), respectively. Among the four BGU-recurred patients in whom H. pylori had been eradicated, one patient was found to have BGU recurring with H. pylori positive again in one year, and another two patients had NSAIDs ingestion history.

CONCLUSION

The eradication of H. pylori in patients with BGU reduces the recurrence of BGU. In addition, the major causes of BGU recurrence look like NSAIDs ingestion and reinfection of H. pylori.

Increased potency of an aptameric G-rich oligonucleotide is associated with novel functional properties of phosphorothioate linkages

We previously showed that inhibition of the expression of CD28 (an essential immune receptor on T cells) mediated by a phosphorothioate (PS)-modified aptameric oligodeoxynucleotide (ODN) sequence, GR1, resulted in reduced T cell responses in vitro and in vivo. Using GR1 sequences differing only in the amount of terminal PS linkages (chimeric SO-ODN), the present study demonstrated that even after a substantial reduction in PS linkages, this 18-mer ODN sequence could still confer functionality in the ODN-mediated inhibition of CD28 expression. We showed that secondary structure and full retention of the ability to form a specific protein-ODN complex and to increase cellular uptake in activated Jurkat T cells were critical parameters in the determination of the magnitude of bioactivity of chimeric SO-ODN. We report that a chimeric SO-ODN with terminal PS linkages that total 9 (ICN 17221) or 12 (ICN 17263) was sufficient to inhibit CD28 expression and suppress in vivo inflammatory ear responses to contact allergen in mice with similar potency to the 17-thioate S-ODN (ICN 16064). Interestingly, all chimeric SO-ODN showed similar in vitro nuclease resistance. These data suggest alternate functional properties for PS linkages, unrelated to nuclease resistance, in enhancing the bioactivity of a G-rich aptamer.

Expression of a non-inactivating K+ channel driven by a rat heat shock promoter increased the resting potential in Aplysia silent neurons

We assessed the role of a non-inactivating K+ channel (aKv5.1) in the resting potential by overexpressing this channel by heat shock in the neurons. A reporter gene lacZ linked to a promoter region spanning from the -285 to the +88 base of the rat HSP70ib gene was induced 62.5-fold when this DNA construct was microinjected into the neurons of the marine mollusk Aplysia and treated with heat shock at 30 degrees C for 3 h. Using this efficient induction system, we induced the expression of aKv5.1 by heat shock in cultured, electrically silent neurons of Aplysia and examined its effect on the resting potential. The channel expression increased the resting potential by approximately 10 mV. This increase was specific to heat shock induction and abolished by treatment with TEA, a specific K+ channel blocker. These results provide the direct evidence that a low voltage-activated, non-inactivating K+ channel can contribute to the resting potential.

Ribavirin polarizes human T cell responses towards a Type 1 cytokine profile

BACKGROUND/AIMS

The therapeutic benefit of ribavirin, a nucleoside analog, in the treatment of chronic HCV infection is seen even in the absence of any apparent direct antiviral effect. We surmised that ribavirin may act by eliciting altered virus-specific immune responses. Because antiviral immunity is predominantly mediated by cytotoxic T cells and antiviral cytokines, we sought to determine whether ribavirin could promote antiviral (Type 1) cytokine expression in human T cells.

METHODS

Isolated human T cells were activated in vitro with enterotoxin B or with phorbol ester plus ionomycin. Cytokine ELISAs were performed on culture supernatants, cytokine mRNA was detected following RT-polymerase chain reaction of T cell RNA, and T cell proliferation measured using MTT assay.

RESULTS

Ribavirin enhanced a Type 1 (IL-2, IFNgamma, TNFalpha) while suppressing a Type 2 cytokine response (IL-4, IL-5 and IL-10), at the level of both protein and mRNA expression. Ribavirin mediated comparable effects on cytokine expression both following activation of specific T cell subpopulations with superantigen and following activation of a larger percentage of T cells via pharmacologic means. The in vitro effect on cytokine expression following ribavirin treatment was comparable in both CD4+ or CD8+ T cell subsets and was observed in a dose range that promoted T cell proliferation.

CONCLUSIONS

These data support the view that ribavirin promotes a Type 1 cytokine-mediated immune response, a property which may account in part for its ability to enhance the antiviral activity of interferon-alpha in the treatment of chronic HCV infection.

Differential localization and activity of the A- and B-forms of the human progesterone receptor using green fluorescent protein chimeras

Subcellular localization and transcriptional activity of green fluorescent protein-progesterone receptor A and B chimeras (GFP-PRA and GFP-PRB) were examined in living mammalian cells. Both GFP-PRA and B chimeras were found to be similar in transcriptional activity compared with their non-GFP counterparts. GFP-PRA and PRA were both weakly active, while GFP-PRB and PRB gave a 20- to 40-fold induction using a reporter gene containing the full-length mouse mammary tumor virus long-terminal repeat linked to the luciferase gene (pLTRluc). Using fluorescence microscopy, nuclear/cytoplasmic distributions for the unliganded and hormone activated forms of GFP-PRA and GFP-PRB were characterized. The two forms of the receptor were found to have distinct intracellular distributions; GFP-PRA was found to be more nuclear than GFP-PRB in four cell lines examined. The causes for and implications of this differential localization of the A and B forms of the human PR are discussed.

Tomographic reconstruction of the retina using a confocal scanning laser ophthalmoscope

Retinal imaging with a confocal scanning laser ophthalmoscope (cSLO) involves scanning a small laser beam over the retina and constructing an image from the reflected light. By applying the confocal principle, tomographic images can be produced. However, the thickness of such slices, when compared with the retinal thickness, is too large to give useful 3D retinal images. In this study an algorithm has been developed which fits a double Gaussian curve to the axial intensity profiles generated from a stack of image slices. The underlying assumption is that the laser light has mainly been reflected by two structures in the retina, the internal limiting membrane and the retinal pigment epithelium. From the fitted curve, topographic images and novel thickness images of the retina can be generated. The technique has been applied to three normal volunteers and seven patients with macular pathology (cystoid macular oedema and macular hole) demonstrating the clinical value of the technique. The improvement in accuracy achieved by using a double rather than a single Gaussian is also demonstrated.

Simultaneous visualization of the yellow and green forms of the green fluorescent protein in living cells

In this study we sought to develop a method for the co-localization of proteins in living cells utilizing the enhanced green fluorescent protein (EGFP) and a red-shifted EGFP variant, EYFP (enhanced yellow fluorescent protein). EYFP was expressed as an unsubstituted molecule while EGFP was fused to NF1 (EGFP-NF1), a transcription factor found exclusively in the nucleus. The Leica TCS SP laser scanning confocal microscope was used. This microscope allows the user to monitor the emitted light at defined wavelengths owing to the presence of a monochrometer in the emission light path. pEGFP-NF1 and pEYFP were co-expressed in the same cell and excited with the 476-nm and 488-nm argon laser lines. To separate the EYFP and EGFP fluorescence, EGFP-NF1 emission was recorded between 496 and 505 nm. These wavelengths are on the left shoulder of the EGFP emission peak and exclude most of the EYFP fluorescence. The EYFP emission was followed between 670 and 754 nm, utilizing the tail of EYFP emission that extends well beyond that for EGFP. Under these conditions we obtained excellent discrimination between EYFP fluorescence and EGFP-NF1 emission. These observations demonstrate that EYFP- and EGFP-substituted chimeras can be used for simultaneous detection in living cells.

Prediction of an anti-IgE binding site on IgE

A combination of computation techniques have been used to determine the binding site and amino acid residues on IgE that are critical for binding to a therapeutic anti-IgE. Homology modeling was used to model parts of IgE and of an antibody that binds to IgE. Docking simulations using shape descriptions were then carried out using the models to determine which residues in the IgE are involved in the binding interaction. The anti-IgE has been determined to bind close to some of the residues that are believed to be in the Fc(epsilon)RI receptor site on IgE, therefore preventing IgE from binding to Fc(epsilon)RI on mast cells and basophils and causing the release of pharmacologic mediators from these cells. Experiments have been suggested to verify the binding site and the residues involved in binding to anti-IgE.

Undescended testes: incidence in 1,002 consecutive male infants and outcome at 1 year of age

In a study of 1,002 consecutive Malaysian male newborns, 48 (4.8%) were found to have undescended testes (UDT). The rate and laterality of the UDT were associated with lower birth weight (P < 0.001) and prematurity (P < 0.001). Boys with UDT were also more likely to have other congenital abnormalities of the external genitalia, the commonest being hydrocele. No correlation between UDT and maternal age, birth order, social class, or mode of delivery was demonstrated in this study. Although 26/34 (76.5%) of UDT achieved full spontaneous descent by 1 year of age, 1.1% of all infants whose testes remained undescended required regular long-term follow-up with surgical referral and correction at an appropriate time. A premature infant with UDT is more likely to achieve full testicular descent at 1 year of age than a term infant.

Connections of the hippocampal formation in humans: I. The mossy fiber pathway

The hippocampal formation has been one of the most extensively studied cortical regions in rats, yet little is known about the anatomical connections of the hippocampus in primates, especially humans. With the use of an antibody against the calcium-binding protein, calbindin-D28K, in normal autopsy tissue and the neuronal tracers biocytin or biotinylated dextrans in in vitro slice preparations from tissue removed during surgery for intractable epilepsy, we examined the human hippocampal mossy fiber pathway. The injections of biocytin into the dentate granule cell layer labeled neurons in a Golgi-like manner, revealing the presence of basal dendrites on about 30% of the granule cells. The granule cell axons, the mossy fibers, initially formed a diffuse plexus of fibers in the polymorphic layer before organizing into fiber fascicles in the hilar pyramidal region. These fiber fascicles were much more prominent rostrally than caudally. Within the hilus and proximal portions of the extrahilar CA3 field, the mossy fibers ran through the pyramidal cell layer, and while near the transition to field CA2, the fibers turned superficially and crossed the pyramidal layer to run in the stratum lucidum. All of these features, seen following injections of tracer into hippocampal slices from the brains of epileptics, were confirmed by calbindin-staining of mossy fibers in normal brains. Biocytin-labeled mossy fiber axons revealed two characteristic types of enlargements: small varicosities and larger expansions. The expansions were found throughout the neuropil and were highly irregular, diaminobenzidine-dense profiles that had pleiomorphic modes of attachment to the parent axon. Electron microscopic images of these biocytin labeled expansions revealed that they were large synaptic boutons bearing asymmetric synapses. This study indicates that the human mossy fiber pathway shows some minor deviations from the rodent brain but little difference from monkeys. We argue that these changes mirror a phylogenetic growth of the CA3 pyramidal neurons (subfield CA3c) into the hilus rather than an evolutionary change of the mossy fiber pathway. This growth of subfield CA3c and the increase in mossy fibers running through the pyramidal layer (and a presumed accompanying increase in proximal basal dendritic contacts) may reflect a growing role of the projection from the dentate granule cells to subfield CA3c and from there to field CA1 in the primate hippocampus.

Connections of the hippocampal formation in humans: II. The endfolial fiber pathway

We investigated the anatomical connections of the pyramidal neurons located within the hilar region of the dentate gyrus of the human hippocampus, neurons which do not have a rodent equivalent. The myeloarchitectural patterns of the human hippocampus indicated the presence of a distinct fiber pathway, the endfolial fiber pathway, in the stratum oriens of the hilus and field CA3. By using the fluorescent lipophilic dye DiI in formalin-fixed human hippocampal tissue, we demonstrated that this is a continuous fiber pathway between the deep hilar region and CA2. This fiber pathway did not enter the fimbria or alveus along the entire distance of the traced pathway and ran exclusively in the stratum oriens of the hilus and CA3. Tracing studies with biocytin in in vitro human hippocampal slices indicated that the hilar and CA3 pyramidal neurons contributed to this pathway. Out distally in field CA3, the long transverse fibers became short and choppy, suggesting that they were beginning to move out of the plane of the tissue slice. Numerous fibers from this pathway were seen crossing the pyramidal layer. Based on comparative studies, we propose that the endfolial fiber system is a component of the hilar Schaffer collateral system in humans. The presence of a significant Schaffer collateral system from the pyramidal neurons in the hilar region would indicate that these neurons are anatomically related to the CA3 pyramidal neurons. Therefore, we suggest the inclusion of the human hilar pyramidal neurons within Lorente de No's field CA3 and, in particular, within subfield CA3c.

Accuracy and precision of NMR relaxation experiments and MD simulations for characterizing protein dynamics

Model-free parameters obtained from nuclear magnetic resonance (NMR) relaxation experiments and molecular dynamics (MD) simulations commonly are used to describe the intramolecular dynamical properties of proteins. To assess the relative accuracy and precision of experimental and simulated model-free parameters, three independent data sets derived from backbone 15N NMR relaxation experiments and two independent data sets derived from MD simulations of Escherichia-coli ribonuclease HI are compared. The widths of the distributions of the differences between the order parameters for pairs of NMR data sets are congruent with the uncertainties derived from statistical analyses of individual data sets; thus, current protocols for analyzing NMR data encapsulate random uncertainties appropriately. Large differences in order parameters for certain residues are attributed to systematic differences between samples for intralaboratory comparisons and unknown, possibly magnetic field-dependent, experimental effects for interlaboratory comparisons. The widths of distributions of the differences between the order parameters for two NMR sets are similar to widths of distributions for an NMR and an MD set or for two MD sets. The linear correlations between the order parameters for an MD set and an NMR set are within the range of correlations observed between pairs of NMR sets. These comparisons suggest that the NMR and MD generalized order parameters for the backbone amide N-H bond vectors are of comparable accuracy for residues exhibiting motions on a fast time scale (< 100 ps). Large discrepancies between NMR and MD order parameters for certain residues are attributed to the occurrence of "rare" motional events over the simulation trajectories, the disruption of an element of secondary structure in one of the simulations, and lack of consensus among the experimental data sets. Consequently, (easily detectable) severe distortions of local protein structure and infrequent motional events in MD simulations appear to be the most serious artifacts affecting the accuracy and precision, respectively, of MD order parameters relative to NMR values. In addition, MD order parameters for motions on a fast (< 100 ps) timescale are more precisely determined than their NMR counterparts, thereby permitting more detailed dynamic characterization of biologically important residues by MD simulation than is sometimes possible by experimental methods. Proteins 28:481-493, 1997.

Partial anatomical and physiological characterization and dissociated cell culture of the nervous system of the marine mollusc Aplysia kurodai

Snail nervous systems are powerful tools for neurobiological studies as the biophysical properties of the giant neurons and their neural circuits can be examined in relation to specific behaviors of animals. The marine mollusc Aplysia californica is particularly useful for analyzing the components of learning and memory at the molecular and cellular levels. Here we partially examined the nervous systems of two species (A. kurodai and A. juliana) commonly found along the Korean coast in comparison with that of A. californica, one of the American marine snails. A. kurodai appeared to be identical to A. californica in both anatomical and physiological properties of the nervous system. A. juliana could be distinguished from A. californica in certain morphological aspects of the nervous system. The hemolymph either from A. kurodai or from A. juliana was required for effectively elongating neurite outgrowth of A. kurodai neurons in dissociated cell culture. The cultured cells retained neuronal properties such as neurite outgrowth, synapse formation, and generation of action potentials. The sensory cells of A. kurodai in dissociated cultures showed a response to serotonin (5-HT) of spike broadening and enhanced membrane excitability as in intact ganglia. Therefore, the nervous system and dissociated neuronal culture of A. kurodai may be useful for studying learning and memory in the context-of well-defined neural circuits of A. californica.

Mutation in the phosphorylation sites of MAP kinase blocks learning-related internalization of apCAM in Aplysia sensory neurons

The synaptic growth that accompanies 5-HT-induced long-term facilitation of the sensory to motor neuron connection in Aplysia is associated with the internalization of apCAM at the surface membrane of the sensory neuron. We have now used epitope tags to examine the fate of each of the two apCAM isoforms (membrane bound and GPI-linked) and find that only the transmembrane form is internalized. This internalization can be blocked by overexpression of transmembrane constructs with a single point mutation in the two MAPK consensus sites, as well as by injection of a specific MAPK antagonist into sensory neurons. These data suggest MAPK phosphorylation at the membrane is important for the internalization of apCAMs and, thus, may represent an early regulatory step in the growth of new synaptic connections that accompanies long-term facilitation.

Grit blasting and the marginal accuracy of two ceramic veneer systems--a pilot study

STATEMENT OF PROBLEM

Margins of ceramic restorations can be damaged during removal of investment materials with grit blasting and result in relatively large marginal discrepancies and excessive marginal discrepancies with greater exposure of cement to the oral environment. Subsequent dissolution of cement can encourage plaque retention, dental caries, and periodontal problems.

PURPOSE

This study compared marginal adaptation of ceramic veneers created by the refractory die technique (R), Dicor glass ceramic technique (D), and effects of grit blasting on their margins.

MATERIAL AND METHODS

Two groups of ceramic veneers were constructed for each system, one without grit blasting (R g and D g) and one with grit blasting (R+g and D+g).

RESULTS

Statistical analyses revealed that grit blasting had a greater effect in reducing marginal accuracy for Dicor ceramic veneers compared with refractory die ceramic veneers.