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.

Sequence-independent inhibition of RNA transcription by DNA dumbbells and other decoys

DNA dumbbells are stable, short segments of double-stranded DNA with closed nucleotide loops on each end, conferring resistance to exonucleases. Dumbbells may be designed to interact with transcription factors in a sequence-specific manner. The internal based paired sequence of DNA dumbbells in this study contains the X-box, a positive regulatory motif found in all MHC class II DRA promoters. In electrophoretic mobility shift assays (EMSAs), dumbbells and other oligonucleotides ('decoys') with the core X-box sequence were found to compete with the native strand for binding to X-box binding proteins (including RFX1). However, only the X-box dumbbell was capable of forming detectable complexes with such proteins using EMSA. In a model cell system, dumbbells were tested for their ability to block RFX1VP16 activation of a plasmid containing multiple repeats of the X-box linked to the CAT gene. While it appeared that dumbbells could block this activation, the effect was non-specific. This and further evidence suggests an inhibition of transcription, most likely via an interaction with the general transcriptional machinery.

Oligonucleotide-mediated inhibition of CD28 expression induces human T cell hyporesponsiveness and manifests impaired contact hypersensitivity in mice

Ligation of CD28 provides a costimulatory signal essential for Ag-mediated T cell activation via the TCR. Blocking CD28 ligation can inhibit cytokine expression and elicits a state of T cell hyporesponsiveness. In this study, we examined the effect of inhibiting CD28 expression on in vitro and in vivo T cell responses. To address this, we have synthesized a series of G-rich phosphorothioate oligonucleotides that inhibited activation-induced transcription and cell surface expression of CD28 on human T cells. CD28 blockade was selective, as expression of other activation-induced receptors was unaffected by oligonucleotide treatment. Using strategic changes to base composition, we identified a minimal 12-mer sequence, containing two sets of four contiguous guanosines separated by 3 to 5 bases, which conferred activity in vitro. Furthermore, inhibition of CD28 expression mediated by one representative active oligonucleotide, GR1, resulted in a concomitant dose-dependent diminution of anti-CD3/PMA-induced cytokine (IL-2, IFN-gamma, IL-8) production. Inhibition of IL-2 synthesis was dependent on CD28 expression, as GR1 failed to abrogate activated IL-2 production in a CD28-deficient T cell line, HUT 78. The inhibitory activity of GR1 reduced T cell proliferative responses in MLR and induced Ag-specific T cell hyporesponsiveness to alloantigens. Finally, s.c. administration of GR1 impaired in vivo contact hypersensitivity responses in mice and was associated with substantially decreased CD28 and IFN-gamma mRNA expression in lymph node cells. Collectively, our studies show the tolerogenic potential of oligonucleotide-mediated CD28 inhibition on T cell activation, in vitro and in vivo.

Oligonucleotide-mediated inhibition of CD28 expression induces human T cell hyporesponsiveness and manifests impaired contact hypersensitivity in mice

Ligation of CD28 provides a costimulatory signal essential for Ag-mediated T cell activation via the TCR. Blocking CD28 ligation can inhibit cytokine expression and elicits a state of T cell hyporesponsiveness. In this study, we examined the effect of inhibiting CD28 expression on in vitro and in vivo T cell responses. To address this, we have synthesized a series of G-rich phosphorothioate oligonucleotides that inhibited activation-induced transcription and cell surface expression of CD28 on human T cells. CD28 blockade was selective, as expression of other activation-induced receptors was unaffected by oligonucleotide treatment. Using strategic changes to base composition, we identified a minimal 12-mer sequence, containing two sets of four contiguous guanosines separated by 3 to 5 bases, which conferred activity in vitro. Furthermore, inhibition of CD28 expression mediated by one representative active oligonucleotide, GR1, resulted in a concomitant dose-dependent diminution of anti-CD3/PMA-induced cytokine (IL-2, IFN-gamma, IL-8) production. Inhibition of IL-2 synthesis was dependent on CD28 expression, as GR1 failed to abrogate activated IL-2 production in a CD28-deficient T cell line, HUT 78. The inhibitory activity of GR1 reduced T cell proliferative responses in MLR and induced Ag-specific T cell hyporesponsiveness to alloantigens. Finally, s.c. administration of GR1 impaired in vivo contact hypersensitivity responses in mice and was associated with substantially decreased CD28 and IFN-gamma mRNA expression in lymph node cells. Collectively, our studies show the tolerogenic potential of oligonucleotide-mediated CD28 inhibition on T cell activation, in vitro and in vivo.

Control of C. elegans larval development by neuronal expression of a TGF-beta homolog

The Caenorhabditis elegans dauer larva is specialized for dispersal without growth and is formed under conditions of overcrowding and limited food. The daf-7 gene, required for transducing environmental cues that support continuous development with plentiful food, encodes a transforming growth factor-beta (TGF-beta) superfamily member. A daf-7 reporter construct is expressed in the ASI chemosensory neurons. Dauer-inducing pheromone inhibits daf-7 expression and promotes dauer formation, whereas food reactivates daf-7 expression and promotes recovery from the dauer state. When the food/pheromone ratio is high, the level of daf-7 mRNA peaks during the L1 larval stage, when commitment to non-dauer development is made.

The binding mode of an E-64 analog to the active site of cathepsin B

Two binding modes of the isobutyl-NH-Eps-Leu-Pro inhibitor to cathepsin B have been proposed. Molecular docking using an empirical force field was carried out to distinguish between the two modes. The search began with manual docking, followed by random perturbations of the docking conformation and cycles of Monte Carlo minimization. Finally, molecular dynamics was carried out for the most favorable docking conformations. The present calculations predict that the isobutyl-NH-Eps-Leu-Pro inhibitor preferentially binds to the S' rather than the S subsites of cathepsin B. The S' binding mode prediction is supported by the X-ray crystal structure of cathepsin B bound to a closely related ethyl-O-Eps-Ile-Pro inhibitor, which was found to bind in the S'subsite with the C-terminal epoxy ring carbon making a covalent bond to the sulfur atom of Cys29. This agreement, in turn, validates our docking strategy. Furthermore, the calculations provide evidence that the dominant contribution to the total stabilization energy of the enzyme-inhibitor complex stems from the strong electrostatic interaction between the negatively charged C-terminal carboxylate group of the ligand and the positively charged imidazolium rings of His110 and His111. The latter are stabilized and held in an optimal orientation for interactions with the C-terminal end of the ligand through a salt bridge between the side chains of His110 and Asp22. By comparison with the crystal structure, some insight into the specificity of the epoxyldipeptide family towards cathepsin B inhibition has been extracted. Both the characteristics of the enzyme (e.g. subsite size and hydrophobicity) as well as the nature of the inhibitor influence the selectivity of an inhibitor towards an enzyme.

Positive charge at position 549 is essential for phosphatidylinositol 4,5-bisphosphate-hydrolyzing but not phosphatidylinositol-hydrolyzing activities of human phospholipase C delta1

Point mutagenesis, phosphatidylinositol (PI), and phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis assays and equilibrium centrifugation PIP2 assays were used to study the functional roles of four highly conserved arginine residues in the Y region of human phospholipase C delta1 (PLCdelta1) (Arg-527, -549, -556, -701). Most of the mutant enzymes were either partially defective or fully active in their abilities to catalyze the hydrolysis of PI or PIP2. However, upon substitution of Arg-549 by glycine or histidine, the mutant enzyme was defective in its ability to catalyze the hydrolysis of PIP2, but it is still able to hydrolyze PI. Replacing Arg-549 with lysine had little effect on the level of PI and PIP2 hydrolytic activities of the mutant enzyme. The residual PIP2 hydrolyzing activity of R549H is highly dependent on pH. R549H showed 5-10% of the PIP2-hydrolyzing activity of the native enzyme between pH 5 and 7 and nondetectable PIP2-hydrolyzing activity at pH 8. The PIP2-hydrolyzing activity of R549G was not detectable at all pH values. Kinetic analysis of PLCdelta1-catalyzed PIP2 hydrolysis revealed that the micellar dissociation constant Ks and interfacial Michaelis constant Km were similar in the native, R549K, and R549H enzymes; but the specific activity at the saturated substrate mole fraction and infinite level of substrate (Vmax) of the R549H mutant were reduced by a factor of 15. PIP2 competitively inhibits the native enzyme to hydrolyze PI at both pH 7 and 8. However, PIP2 inhibits R549H only at pH 7.0 and does not inhibit R549G at either pH. Taken together, these results suggest that positive charge at position 549 of PLCdelta1 protein is essential for the enzyme to recognize and catalyze the hydrolysis of PIP2 but not PI.

A simple clinical method to measure the optic disc size in glaucoma

PURPOSE

The cup-to-disc ratio is a widely used clinical measure of optic nerve damage in the management of glaucoma patients and those suspected of having glaucoma. Knowledge of the optic disc size allows for a better assessment of the clinical significance of the cup-to-disc ratio. In this study, two optical methods-slit-lamp biomicroscopy and confocal scanning laser ophthalmoscopy-were used to measure the vertical disc diameter as an indirect measure of optic disc size. The aim was to provide a simple and clinically useful examination technique in the management of glaucoma.

METHODS

The vertical optic disc diameter was measured with aspheric lenses (Volk 60, 78, and 90 D, and Nikon 60 and 90 D) using slit-lamp biomicroscopy in 25 emmetropic normal volunteers. The average of three readings was determined for each of the lenses and the measurements were correlated with the magnification-corrected diameter measured with the Heidelberg Retina Tomograph.

RESULTS

The mean vertical disc diameter of the group, as measured with the Heidelberg Retina Tomograph, was 1.81 +/- 0.18 mm. Results obtained with the lower-power lenses correlated best with the Heidelberg Retina Tomograph measurements (for example, Volk 60 D: r = 0.80, p = 0.0001, 95% confidence interval 1.76-1.85 mm), whereas the 90-D correlation was the weakest (for example, Volk 90 D: r = 0.59. p = 0.002, 95% confidence interval 1.75-1.87 mm). With the Volk 60-D lens, the "best fit" equation for estimating disc diameter, in millimetres, is Y = 0.85X + 0.06, where Y is the Heidelberg Retina Tomograph value and X is the slit-lamp biomicroscopy measurement.

CONCLUSION

Using these formulae, the clinician is able to estimate the optic disc diameter with sufficient accuracy to allow clinical decisions to be made in the evaluation of patients with glaucoma, without recourse to expensive technology.

Colour Doppler imaging in giant cell (temporal) arteritis: serial examination and comparison with non-arteritic anterior ischaemic optic neuropathy

The ophthalmological manifestations of giant cell arteritis (GCA) present a difficult diagnostic and management problem to the ophthalmologist. The orbital circulation is frequently involved in the disease process. The effects of GCA on orbital blood flow assessed by colour Doppler imaging (CDI) were investigated in this study. Serial CDI examinations of the orbital blood vessels were performed (at presentation, 2 days, 1 week and at 1 month) on 7 patients with GCA. CDI examination at presentation was also performed on 4 patients with non-arteritic anterior ischaemic optic neuropathy (AION) for comparison. Blood flow could not be detected in up to three arteries in the affected (ipsilateral) orbit of 6 GCA patients at presentation. Five of these patients were also found to have undetectable blood flow in the posterior ciliary arteries of the contralateral orbit. Serial CDI examination revealed blood flow alterations in arteritic patients despite treatment. Return of blood flow to normal was slow, and related to the clinical features. By contrast, only 1 of the patients with non-arteritic AION showed undetectable blood flow in a posterior ciliary artery. GCA leads to widespread and prolonged alterations in orbital blood flow. CDI allows the detection and monitoring of such alterations in orbital blood flow, which correlate with the clinical features of GCA. Serial CDI examinations in GCA may be used to aid management decisions.

Gestational diabetes in Singaporean women: use of the glucose challenge test as a screening test and identification of high risk factors

In this study, 1141 antenatal women attending 9 Government polyclinics were screened between 24 and 28 weeks of gestation for gestational diabetes mellitus (GDM) using the glucose challenge test (GCT). An attempt was made to determine whether 7.2 mmol/l or 7.8 mmol/l was an effective cut-off point as an indicator for GDM. The women with GCT levels of > or = 7.2 mmol/l had an oral glucose tolerance test (OGTT) for confirmation of GDM. The results showed that 420 (36.8%) had GCT levels > or = 7.2 mmol/l, including 299 (26.2%) with GCT levels of > or = 7.8 mmol/l. Of the 190 OGTT carried out, 8 (4.2%) were confirmed to have GDM, all of whom had GCT levels of > or = 7.8 mmol/l, indicating that a GCT level of 7.8 mmol/l was the effective cut-off point. Univariate analysis showed that epidemiological features associated with a raised GCT > or = 7.8 mmol/l were, older age that is 30 years and above, Chinese ethnic group, maternal obesity (body mass index > or = 25) and history of > or = 4 pregnancies. Multivariate analysis using stepwise logistic regression, showed that factors significantly and independently associated with raised GCT levels were older age, Chinese ethnic group and maternal obesity. All antenatal women should be screened for GDM using the GCT, and those with levels of > or = 7.8 mmol/l should be subjected to the OGTT for confirmation.

The value of multiple free-flow studies in men with lower urinary tract symptoms

OBJECTIVE

To assess the variability of free-flow studies in men presenting with lower urinary tract symptoms (LUTS) suggestive of benign prostatic obstruction (BPO) and to determine the sensitivity, specificity and predictive values of consecutive measurements of maximum flow rate for the presence of bladder outlet obstruction (BOO) at several threshold values.

PATIENTS AND METHODS

The value of multiple free-flow studies was assessed in 165 men presenting with LUTS suggestive of BPO. Each patient was requested to void four times into a uroflowmeter and the voided volume and post-void residual urine volume (PVR) were also measured. The variability of the maximum flow rate (Qmax), voided volume and PVR between consecutive voids was assessed. In addition, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of various thresholds of Qmax for the presence of BOO were calculated for each consecutive void.

RESULTS

The mean Qmax on void 1 was 10.2 mL/s and the mean maximum value for Qmax between voids 1 and 2 was 12.5 mL/s. For voids 1, 2 and 3, the mean maximum Qmax was 13.9 mL/s and for voids 1 to 4 it was 15.2 mL/s. There were no significant changes in PVR among any of these voids. There was a statistically significant, although small, decrease in voided volume between voids 1 to 3 and voids 1 to 4. The specificity and PPV of Qmax for BOO increased with each subsequent void, such that using a threshold value for Qmax of 10 mL/s on the fourth void, the specificity and PPV for BOO were 96% and 93%, respectively.

CONCLUSIONS

There was a significant increase in Qmax with each successive void when men with LUTS suggestive of BPO performed multiple free-flow measurements and consequently, single free-flow measurements substantially underestimated the maximum Qmax that these patients achieved. The specificity and PPV of Qmax for BOO can be improved considerably by performing multiple free-flow studies and by carefully selecting an appropriate threshold value (although whether pressure-flow studies are unnecessary will depend on what level of specificity and PPV is deemed acceptable in clinical practice). These findings should be considered if free-flow studies are to be used as the basis for deciding the clinical management of men with LUTS and may be particularly useful for urologists with limited facilities for pressure-flow studies.

The significance of terminal dribbling in men with lower urinary tract symptoms

OBJECTIVE

To determine the relationship between the symptom of terminal dribbling, objective evidence of terminal dribbling on recordings of uroflow, benign prostatic enlargement (BPE) and bladder outlet obstruction (BOO) in men with lower urinary tract symptoms (LUTS).

PATIENTS AND METHODS

The prevalence of the symptom of terminal dribbling was determined from a symptom questionnaire completed by 165 men presenting with LUTS. Objective evidence of terminal dribbling during voiding was assessed from uroflow recordings and prostate volume was measured by transrectal ultrasonography. Combined pressure-flow studies were performed to determine the presence or absence of BOO.

RESULTS

There was relatively poor agreement between the symptom of terminal dribbling and objective evidence of its presence; 48% of the patients who reported terminal dribbling most or all of the time showed no objective evidence of terminal dribbling on uroflowmetry. The symptom of terminal dribbling was not significantly related to the presence of BOO (P = 0.74) and the group-specific urethral resistance factor (URA) did not differ significantly (P = 0.79) between those men who complained of terminal dribbling and those who did not (median URA 33 and 31 cmH2O, respectively). However, objective evidence of terminal dribbling on uroflow traces was significantly related to BOO (P < 0.001) and those patients with objective evidence of terminal dribbling had higher values of URA (median 39 compared with 28 cmH2O). Objective terminal dribbling had a specificity of 92% and positive predictive value of 88% for the presence of BOO. Neither the symptom of terminal dribbling nor objective evidence of its presence were significantly related to prostatic enlargement.

CONCLUSION

While the symptom of terminal dribbling is probably not related to BOO or prostatic enlargement, objective evidence of terminal dribbling on flow curve recording is specific for BOO and as such, its presence could potentially be of value in the assessment of men with LUTS.

Significance of intermittency in men with lower urinary tract symptoms

OBJECTIVES

To determine the relationship between the symptom of intermittency, objective evidence of intermittency on uroflow traces, benign prostatic enlargement, and bladder outlet obstruction (BOO) in men with lower urinary tract symptoms (LUTS).

METHODS

The prevalence of the symptom of intermittency was determined from a symptom questionnaire in 165 men presenting with LUTS. Objective evidence of intermittency during voiding was assessed from uroflow traces, and prostate volume was measured by transrectal ultrasound. Combined pressure-flow studies were performed to determine the presence or absence of BOO.

RESULTS

There was relatively poor agreement between the symptom of intermittency and objective evidence of its presence. Of the 35 patients who reported intermittency most or all of the time, 21 showed no objective evidence of intermittency on uroflowmetry. The symptom of intermittency was not significantly related to the presence of BOO (P = 0.42) and the group-specific urethral resistance factor (URA) did not differ significantly (P = 0.87) between those men who complained of intermittency and those who did not (median URA, 35 versus 32 cm H2O). However, objective evidence of intermittency on uroflow traces was significantly related to BOO (P = 0.016), and those patients with objective evidence of intermittency had higher URA values (median, 43 versus 32 cm H2O). Objective evidence of intermittency had a specificity of 98% and positive predictive value of 92% for the presence of BOO. Neither the symptom of intermittency nor objective evidence of its presence was significantly related to prostate size.

CONCLUSIONS

Although the symptom of intermittency does not seem to be related to BOO or prostate size, objective evidence of intermittency on flow curve traces is specific for outflow obstruction, and as such its presence could potentially be of value in the assessment of men with lower urinary tract symptoms.

Gastric stump carcinoma: a surgical challenge

Gastric stump carcinoma is a carcinoma arising in the stomach remnant following previous gastric resection. It is a distinct disease entity with its unique aetiology and pathogenesis. We report 3 cases of gastric stump carcinoma encountered in the department over the past 5 years and review current literature pertaining to its clinical presentation, aetiology, pathogenesis, treatment strategy and the role of screening endoscopy. The disease is characterised by its late presentation and dismal prognosis and will continue to pose a surgical challenge in the years to come.

The obstructive effect of a urethral catheter

PURPOSE

The effect of a urethral catheter on pressure-flow relationships of the urethra has important implications for the practice to this question in the past in men with benign prostatic hyperplasia. We assessed the obstructive effect of an 8 Ch. urethral catheter in men who presented with lower urinary tract symptoms due to benign prostatic hyperplasia.

MATERIALS AND METHODS

During combined pressure-flow studies 59 men completed 2 voids of similar volume with and without a urethral catheter in situ. Maximum flow rate, detrusor pressure at maximum flow and the group of specific urethral resistance factor were measured and compared between these 2 voids.

RESULTS

There was no significant difference in maximum flow rate between voids (with catheter 9.1 ml. per second versus without catheter 8.6 ml. per second). Although detrusor pressure was significantly greater with the urethral catheter in situ (80 versus 67 cm. water), voids (with catheter 42.1 cm, water versus without catheter 36.6 cm water).

CONCLUSIONS

A 8 Ch. catheter does not appear to have a significant obstructive effect in the urethra. This finding has important implications for the practice and interpretation of pressure-flow studies.

Molecular dynamics simulation of E. coli ribonuclease H1 in solution: correlation with NMR and X-ray data and insights into biological function

A 500 ps molecular dynamics simulation of Escherichia coli RNase H1 in the presence of explicit water molecules has been carried out to aid in the interpretation of NMR N-H backbone model free parameters and X-ray B-factor values of the free enzyme. Both experimental techniques have revealed unusual structural and dynamic features of the protein. Atomic fluctuations (B-factors) and re-orientational motions of the backbone heteronuclear bonds (order parameters) computed from the simulation are compared with results obtained from experiments. Qualitative agreement is obtained between the computed and X-ray B-factors, whereas the agreement between the computed and NMR generalized order parameters is as good as quantitative for most residues. Reasons for significant discrepancies, the physical basis and the plausible biological consequences of the observed protein dynamics are discussed.

Identifying the mechanism of protein loop closure: a molecular dynamics simulation of the Bacillus stearothermophilus LDH loop in solution

The 'loop' involving residues 98-110 in Bacillus stearothermophilus lactate dehydrogenase (BSLDH) is of great interest as substrate-induced 'loop' closure is thought to be rate-limiting and essential in catalyzing the reaction and in determining substrate specificity. Consequently, we have explored the mechanism underlying 'loop' opening in BSLDH through a molecular dynamics simulation at high temperature (1000 K) in the presence of explicit solvent, starting from the X-ray structure of BSLDH complexed with the co-enzyme NAD+ and oxamate at 2.5 A. During the simulation, a significant conformational change occurred, as evidenced by sharp dihedral angle transitions, hydrogen bond breaking and formation and large root mean square deviations from the starting structure; these changes define the criteria for 'loop' opening. The mechanical elements responsible for 'loop' opening, i.e. 'loop' hinges and flap, are defined through a combination of order parameters, dihedral angle changes and their correlations and the dynamical cross-correlation map of atomic displacements for the 'loop' residues. The results indicate that the 'loop' consists of two flexible hinge regions on either side of a relatively rigid three-residue segment that undergoes a significant spatial displacement during 'loop' opening. 'Loop' opening is made possible through an array of correlated dihedral angle changes and intra-'loop' rearrangements of hydrogen-bond interactions. The present findings are compared to previous work related to 'loop' opening and site-directed mutagenesis experiments.

The Abrams-Griffiths nomogram

The treatment of benign prostatic hyperplasia and the definition of bladder-outlet obstruction has preoccupied urologists and researchers in recent years. Bladder-outlet obstruction can be defined only by pressure-flow measurement. Various methods of analysis of pressure-flow data have been proposed. The Abrams-Griffiths nomogram is an easy method of classifying these data to distinguish between the presence or absence of obstruction. Using the values for the maximal flow and the corresponding voiding detrusor pressure a point can be plotted on the nomogram that determines whether the bladder outlet is obstructed, unobstructed, or equivocally obstructed. For those that fall in the equivocal zone, further criteria for the mean slope of the pressure-flow plot and the minimal voiding detrusor pressure are used to determine whether there is obstruction or not. The nomogram's prognostic value in predicting the outcome of prostatectomy has been studied and found to be excellent. The Abrams-Griffiths nomogram can be modified by assigning an Abrams-Griffiths number to each set of pressure-flow data. This number is easy to calculate and use and gives a continuous variable that can be used to evaluate the effects of therapy. Although the Abrams-Griffiths nomogram and number are somewhat simplistic, none of the more complex methods of pressure-flow analysis have been shown to be better predictors of treatment outcome to date.

An unusual presentation of carcinoma of the gallbladder--case report

Unusual modes of presentation of carcinoma of the gallbladder have been described in the literature. However, this is probably the first reported case of carcinoma of the gallbladder presenting with acute large bowel obstruction. This paper also reviews the literature pertaining to the clinical features and current treatment of carcinoma of the gallbladder. It continues to be a discouraging disease characterised by late diagnosis and a poor outcome.

Cholinergic innervation in the human hippocampal formation including the entorhinal cortex

The cholinergic innervation of the hippocampal formation is thought to play an important role in memory processes, but its organization in humans has not been described in detail. We studied the cholinergic innervation of the human hippocampal formation by means of immunohistochemistry with polyclonal antisera directed against acetylcholinesterase (AChE), choline acetyltransferase (ChAT), and the low-affinity (p75) nerve growth factor receptor (NGFR). The density of ChAT-like immunoreactive (ChAT-li) fibers differed substantially among the various regions, in general paralleling the pattern of AChE-li staining. One notable exception was the presence of AChE-li cell bodies. In contrast, ChAT immunoreactivity was associated only with fibers and terminals. NGFR-li staining corresponded closely to the ChAT-li fiber pattern. ChAT-li fibers in the CA fields diffusely filled the stratum pyramidale and extended into the stratum oriens and radiatum as well. The highest density was consistently observed in CA4 and CA3 subfields. Staining decreased from CA4 to CA1 and was substantially less dense in the subicular complex. In the entorhinal cortex, the ChAT- and NGFR-li fiber innervation displayed a laminar pattern, most intense over the nests of cells in layer II. There was a trend towards an age-related reduction in the density of ChAT- and AChE-li fibers and terminals. Nonetheless, we also found a surprisingly conserved NGFR-li innervation and the presence of occasional NGFR-li pyramidal cells, providing evidence of a plastic response in the brains of the elderly patients.

The double catalytic triad, Cys25-His159-Asp158 and Cys25-His159-Asn175, in papain catalysis: role of Asp158 and Asn175

The 1.65 A X-ray structure of papain, which exhibits a Cys25-His159-Asn175 triad, does not correspond to the catalytically active ion pair state since Cys25 is oxidized to cysteic acid and His159 is predominantly neutral. Thus, stochastic boundary molecular dynamics simulations starting from the 1.65 A X-ray structure of papain have been performed for Cys25 and His159 in the SH-ImH+, SH-Im, S(-)-ImH+ and S(-)-Im states and for Asp158 mutated to Asn, Glu and Gly in the ion pair state. By comparing the resulting averaged structures and analyzing the trajectories of certain interatomic distances, important differences in the active-site geometry of papain have been found. In particular, the initial Cys25(S-)-His159(ImH+)-Asn175(C = O) triad found in the X-ray structure is retained in all the structures except the wild type and Asp158-->Asn ion pair states where there is a conformational transition to form the triad, Cys25(S-)-His159(ImH+)-Asp158(COO-). Both triads, Cys25(S-)-His159(ImH+)-Asp158(COO-) and Cys25(S-)-His159(ImH+)-Asn175(C = O) are postulated to participate in catalysis and their roles are discussed. Thus, catalysis does not take place from a single steric position but a two-state mechanism.

Effect of ethanol on prostaglandin E2 receptor in rat submandibular salivary glands

The dose-dependent effects of acute ethanol treatment on the prostaglandin E2 (PGE2) receptor in submandibular salivary glands was investigated. Rat submandibular-gland segments were preincubated with Dulbecco's modified Eagle's medium in the absence and the presence of various concentrations of ethanol (0.1-5%). After incubation, membranes were prepared and assayed for PGE2 receptor binding using [3H]-PGE2. Ethanol had no effect on receptor binding at concentrations below 1%, but binding was stimulated by higher concentrations. A 30% increase in binding occurred with 2.5% ethanol and 50% with 5% ethanol. This increase was due to an alteration of the binding characteristics. Scatchard analysis of the data from the control and 5% ethanol groups revealed that the ethanol-induced increase in PGE2 receptor binding was mainly due to a 26 and 58% decrease in the dissociation constant (Kd) for the high- and low-affinity binding sites, respectively. A 31% decrease of binding capacity (Bmax) was also observed in the low-affinity binding sites. The results demonstrate that PGE2 receptor binding in submandibular glands is not altered by acute treatment with ethanol at physiological doses. The receptor binding is also relatively stable on pretreatment with 1% ethanol. It is suggested that the increase of receptor binding induced by high concentrations of ethanol may be a spontaneous response to the decrease of PGE2 synthesis in the tissues.

Cigarette smoking reduces human salivary eicosanoids

The effect of cigarette smoking on salivary eicosanoid levels was investigated in 10 smoker and 10 non-smoker volunteers. The smokers consumed an average of 20 cigarettes/day for the past 5 years or longer. The smoking status was validated by salivary cotinine level. Eicosanoids were extracted from saliva with ethanol, and the radioimmunoassay was performed to determine the concentrations of four major eicosanoids, i.e. prostaglandin E2 (PGE2), PGF2 alpha, 6-sulphidopeptide-containing leukotrienes (LTs) and 12-hydroxyeicosatetraenoic acid (12-HETE). The levels of PGE2, PGF2 alpha, and LTs were significantly lower in the saliva of smokers as compared to that of the non-smokers (1.74 +/- 0.32 vs 2.41 +/- 0.64, p = 0.006; 0.36 +/- 0.12 vs 0.54 +/- 0.18, p = 0.04; 2.24 +/- 0.96 vs 4.92 +/- 1.29, p = 0.006; mean +/- SD, ng/ml saliva). No significant differences were found in the levels of 12-HETE between the two groups. The results suggest that cigarette smoking reduces the concentrations of both the cyclooxygenase and 5-lipoxygenase products in saliva.

Disseminated histoplasmosis presenting with ileal perforation in a renal transplant recipient

A renal transplant patient presented with ileal perforation due to histoplasmosis 3 years after transplantation. Mesenteric lymph nodes and lungs were also affected by the disease. She was successfully treated with amphotericin B followed by ketoconazole.