Clusters of intramembrane particles associated with binding sites for alpha-bungarotoxin in cultured chick myotubes

Developing chick myotubes in tissue culture were freeze-fractured to yield complementary replicas of large areas of membrane. Regions of muscle fibers with high concentrations of acetylcholine receptors were identified by binding of fluorescent-labeled alpha-bungarotoxin. Membranes in such regions contained clusters of large (100 A Diam) angular particles, similar in appearance to particles found in postsynaptic membranes of cholinergic synapses. Particles appeared in apposing areas of cytoplasmic and external leaflets but were more prevalent in the cytoplasmic leaflet. The areas of high particle concentration were coextensive with the fluorescence due to bound toxin. Treatment of cultures with tetrodotoxin increased the size of fluorescent spots and areas of high concentration of particles relative to those found in control cultures. In muscle cultures grown in the presence of spinal cord explants, some neurites contacted and innervated nearby myotubes. Intense fluorescence due to binding or alpha-bungarotoxin was present at portions of such neurite-myotube contacts. At these same portions, a high concentration of large angular particles was present in the sarcolemma adjacent to the neurite. In addition, an ordered arrangement of large particles was seen in the cytoplasmic leaflet of the neuronal plasmalemma directly apposing the muscle. The possible significance of these arrangements is discussed. Clusters on myotubes tended to be larger (contain more particles) when they occurred in groups, defined as three or more clusters with an intercluster distance of less than 0.5 micrometers. Clusters were also larger in myotubes treated with tetrodotoxin and in myotubes adjacent to some neurites in nerve-muscle cocultures. Several depressions containing particles similar to those in the clusters were found in the sarcolemma. The implications of these depressions are discussed in light of current theories of incorporation of proteins into cell membranes.

Buspirone: an anxiolytic without sedative effect

Twelve volunteers with a complaint of chronic insomnia participated in a placebo-controlled, double-blind, crossover study of the effects of buspirone t.i.d. on sleep pattern and daytime function. The drug was tested alone and in combination with flurazepam or triazolam. Buspirone alone did not impair objective measures of daytime wakefulness or performance. Impaired alertness was seen the day after bedtime administration of flurazepam but not after triazolam; buspirone did not alter these effects. Buspirone did not affect the Multiple Sleep Latency Test, a sensitive measure of changes in daytime alertness.

Induction of acetylcholine receptors in muscle cultures

Acetylcholine receptors in muscle cells differentiated in vitro were monitored by using 125 I-alpha-bungarotoxin. The number of cholinergic receptors was increased 4-8 fold in 2 days due to inhibition of spontaneous contraction of the muscle fibers. The inhibition of this activity, whether mediated through tetrodotoxin, lidocaine or D-600, did not affect the biochemical differentiation of muscle, as represented by creatine-phosphokinase and acetylcholinesterase activity. "Induction" of receptors by tetrodotoxin was inhibited by cycloheximide, actinomycin-D, or 5-bromotubericidine. Dystrophic muscle responded in vitro to inhibition of contraction similar to normal tissue.

Age-related alterations of NMDA-receptor properties in the mouse forebrain: partial restoration by chronic phosphatidylserune treatment

The effect of aging on the properties of N-methyl-D-aspartate (NMDA) receptors in the forebrain of female NMRI mice was investigated using the antagonist [3H]MK-801 as radioligand. Compared to young (3 months) mice, aged (20 months) mice showed changes of the properties of the NMDA receptor at three different levels: (1) the density was reduced by about 35%; (2) the efficacy of L-glutamate and glycine for stimulating specific [3H]MK-801 binding was enhanced, probably because more NMDA receptor-associated ion channels are closed under baseline conditions in the aged brain; (3) the affinity of L-glutamate and glycine to its binding sites at the NMDA receptor complex was also enhanced. Chronic treatment of aged mice with phosphatidylserine (20 mg/kg, i.p., once daily) for three weeks completely normalized enhanced efficacy and affinity of L-glutamate and glycine and elevated NMDA receptor density by approximately 25%. These findings are consistent with the assumptions that deficits of the NMDA receptor are one of the mechanisms of age-related cognitive impairment and that the beneficial effects of phosphatidylserine treatment on cognitive deficits of aged individuals might be partially due to the effects of this drug on age-related NMDA receptor deficits.

Gallbladder and biliary tract disease in AIDS

Biliary disease occurs in a subset of AIDS patients with CD4 counts of less than 100 per mm3. These patients present with right upper quadrant and epigastric pain, cholestasis, and usually abnormal findings on imaging. In 75% of patients, an associated opportunistic infection can be identified. In patients with biliary disease, pain is often relieved following endoscopic sphincterotomy, whereas cholecystectomy provides pain relief in patients with acalculous cholecystitis.

Neurochemical and morphological responses to acutely and chronically implanted brain microdialysis probes

The purpose of this study was to compare, in rats, brain microdialysis results obtained using microdialysis probes implanted acutely for 2 h versus probes implanted chronically for 24 h in the caudate. Specific comparisons included: (1) dialysate purine and amino acid profiles during cerebral ischemia; (2) diffusional characteristics of the microdialysis probe; and (3) tissue morphology surrounding the probe. During ischemia, the increase in dialysate levels of adenosine, inosine, and hypoxanthine was less pronounced from probes implanted chronically, while dialysate xanthine levels increased to a greater extent. An increase in dialysate amino acid neurotransmitters during cerebral ischemia was observed in the acutely implanted probes within 10 min of the onset of cerebral ischemia; in the chronically implanted probes this increase did not occur until after 50 min of severe ischemia. Both in vitro and in vivo tests revealed a diffusional barrier in chronically implanted probes. Moreover, the tissue surrounding chronically implanted probes exhibited a high degree of inflammation, and fibrin deposits were substantial. In addition, uric acid levels (an indicator of tissue injury) sampled from chronically implanted probes were 7-fold greater than levels sampled from acutely implanted probes. These data raise concerns about the use of chronically implanted microdialysis probes for the measurement of purine and amino acid profiles during cerebral ischemia.

Partial characterization of the rH1 sodium channel protein from rat heart using subtype-specific antibodies

Three subtype-specific antisera were generated against peptides corresponding to portions of the amino terminus, interdomain 1-2, and carboxy terminus of the rH1 sodium channel primary sequence to confirm the expression of this protein in the adult rat heart and to determine selected biochemical properties of this protein that might contribute to its subtype-specific characteristics. All three antisera identify a 240-kD band on Western blots of partially purified cardiac membrane proteins and by immunoprecipitation of iodinated partially purified membrane proteins. Unlike other characterized mammalian sodium channels, no beta subunit is detected in association with the rH1 alpha subunit. The rH1 alpha subunit is a complex sialoglycoprotein as evidenced by its interaction with wheat germ agglutinin-Sepharose and by reduction in its apparent molecular weight after treatment with neuraminidase; deglycosylation with N-glycanase confirms that the rH1 protein contains significantly less carbohydrate than other sodium channel proteins characterized to date (5% versus 25% to 30%). Consistent with electrophysiological studies indicating a role of phosphorylation in channel regulation, the rH1 alpha subunit can be phosphorylated by the catalytic subunit of cAMP-dependent protein kinase A. The possible functional significance of these findings is discussed.

Incidence and outcomes of bloodstream infections among hematopoietic cell transplant recipients from species commonly reported to be in over-the-counter probiotic formulations

BACKGROUND

Probiotic supplementation has been promoted for numerous health conditions; however, safety in immunosuppressed patients is unknown. We evaluated bloodstream infections (BSIs) caused by common probiotic organisms in hematopoietic cell transplant recipients.

METHODS

All blood culture (BC) results from a cohort of hematopoietic cell transplant recipients transplanted at Fred Hutchinson Cancer Research Center in Seattle, Washington, between 2002 and 2011 were reviewed. Patients with at least 1 positive BC for common probiotic organisms (Lactobacillus species, Bifidobacterium species, Streptococcus thermophilus, and Saccharomyces species) within 1 year post hematopoietic cell transplantation (HCT) were considered cases. Data were collected from center databases, which contain archived laboratory data, patient demographics, and clinical summaries.

RESULTS

A total of 19/3796 (0.5%) patients developed a BSI from one of these organisms within 1 year post HCT; no Bifidobacterium species or S. thermophilus were identified. Cases had a median age of 49 years (interquartile range [IQR]: 39-53), and the majority were allogeneic hematopoietic cell transplant recipients (14/19, 74%). Most positive BCs were Lactobacillus species (18/19) and occurred at a median of 84 days (IQR: 34-127) post transplant. The incidence rate of Lactobacillus bacteremia was 1.62 cases per 100,000 patient-days; the highest rate occurred within 100 days post transplant (3.3 per 100,000 patient-days). Eight patients (44%) were diagnosed with acute graft-versus-host disease of the gut prior to the development of bacteremia. No mortality was attributable to any of these infections.

CONCLUSION

Organisms frequently incorporated in available over-the-counter probiotics are infrequent causes of bacteremia after HCT. Studies evaluating the use of probiotics among high-risk patients are needed.

Sodium channel distribution within the rabbit atrioventricular node as analysed by confocal microscopy

1. Paired 20 microns thick sections of fresh frozen tissue taken from the frontal plane of the rabbit atrioventricular (AV) nodal region were processed for histology and immunohistochemistry. Confocal microscopy was used to image the distribution of sodium channels using IgG (R12) developed against a highly conserved sequence in the interdomain 3-4 region of cloned sodium channels. 2. In ventricular and atrial cells, sodium channel immunofluorescence was localized to lateral membranes and T-tubules. In the open AV node, levels of sodium channel immunofluorescence in the transitional cell zone and in the lower nodal cell tract were comparable to that found in the atrial and ventricular myocardium. 3. In the enclosed AV node a gradation of sodium channel immunofluorescence is present such that peripherally located circumferential transitional cells display high levels of immunofluorescence, comparable to that of atrial and ventricular myocardium, while centrally located midnodal cells display decreased levels of or no immunofluorescence. 4. In order to correlate the distribution of sodium channels with the distribution of gap junctions, we used IgG directed against the carboxyl terminus of connexin43 (CT-360). Ventricular cell immunofluorescence was localized primarily to the intercalated disk region, while in the AV node, the pattern of distribution was found to be similar to that of sodium channels. 5. The reduced levels of and/or absence of immunofluorescence in the midnodal cell region indicates a paucity of sodium channel and connexin43 protein expression in this region of the AV node that would favour slow impulse conduction.

Risperidone for aggression and self-injurious behavior in adults with mental retardation

Risperidone has proven efficacy with reduced likelihood of causing extrapyramidal symptoms in the treatment of schizophrenia. Initial work suggests its utility in the management of aggression and self injury in patients with mental retardation. The use of risperidone in eight adult patients with moderate to profound mental retardation is described. Risperidone in these individuals was associated with significant reduction in aggression and self injurious behavior. Side effects were primarily those of sedation and restlessness. These cases illustrate the possible utility of risperidone in the treatment of aggression and self injury in adult patients with moderate to profound mental retardation.

Hrp12, a novel heat-responsive, tissue-specific, phosphorylated protein isolated from mouse liver

Previous studies from this laboratory identified a 28-kd nonreducible protein, liver-derived immunoinhibitory factor (LDIF) from the mouse liver. Isolation of this protein resulted in the co-purification of another unique protein called heat responsive protein 12 kd (Hrp12). In contrast to LDIF, Hrp12 was totally reducible to a protein of 12 kd suggesting a dimer. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) purification, followed by sequencing of an in situ cyanogen bromide digest of membrane bound Hrp12, yielded an internal 20-amino acid polypeptide. Degenerate oligonucleotides made from this peptide were used to screen a murine liver complementary DNA (cDNA) library. A 1240-bp cDNA clone was obtained with an internal 521-bp open reading frame (ORF). Sequence analysis of the 173-amino acid ORF of mouse Hrp12 showed a high degree of homology with a 99 amino acid rat liver-kidney perchloric acid-soluble protein (LKPS) and a 136-amino acid perchloric acid soluble rat protein (PSP). Transcripts for Hrp12 were mainly restricted to the liver and kidney in mouse and man. The protein was estimated to be approximately 0.8% of the total liver-soluble cytosolic protein. A zoo-blot probed at moderate stringency with labeled cDNA revealed a strong conservation of the gene in all of the mammalian species tested. Analysis of the protein structure of Hrp12 revealed motifs predicted to be targets for protein kinase C (PKC). More importantly, purified mouse Hrp12 could be phosphorylated in vitro with PKC. The protein had significant similarity to DnaK heat shock protein (Hsp)70 and contained a 54-amino acid stretch with sequence similarity to Hsp90. This prompted us to investigate the heat shock response of Hrp12. Isolated hepatocytes and hepatoma cells were exposed to different heat shock temperatures (39.5 degrees C, 42.5 degrees C, and 44.5 degrees C); and then total RNA was extracted and Northern analysis carried out. The message for this novel protein responded atypically to heat shock. Although the steady-state level of the message increased after heat shock, a marked oscillatory pattern was superimposed on it. In contrast, the steady-state levels of Hsp90 and Hsp70 messenger RNA (mRNA) were found to respond to heat shock in the expected manner. Finally, the amount of Hrp12 protein was also found to increase after heat shock in a manner that was consistent with heat-responsive proteins.

Potential future clinical applications for the GPIIb/IIIa antagonist, abciximab in thrombosis, vascular and oncological indications

Abciximab (ReoPro) is a mouse-human chimeric monoclonal antibody Fab fragment of the parent murine monoclonal antibody 7E3, and was the first of these agents approved for use as adjunct therapy for the prevention of cardiac ischemic complications in patients undergoing percutaneous coronary intervention (PCI). Abciximab binds with high avidity to both the non-activated and activated form of the GPIIb/IIIa receptor of platelets, the major adhesion receptor involved in aggregation. Additional cardiovascular indications for abciximab are unstable angina, carotid stenting, ischemic stroke and peripheral vascular diseases. Abciximab also interacts with two other integrin receptors; the a av b b3 receptor, which is present in low numbers on platelets but in high density on activated endothelial and smooth muscle cells, and a aMb b2 integrin which is present on activated leukocytes. Cell types that express integrins GPIIb/IIIa and a av b b3 such as platelets, endothelial and tumor cells have been implicated in angiogenesis, tumor growth and metastasis. Since abciximab interacts with high avidity to integrins GPIIb/IIIa and a av b b3, it is reasonable to assume that it may possess anti-angiogenic properties in angiogenesis-related diseases, as well as anti-metastastatic properties in case of disseminating tumors expressing the target integrin receptors.

Relationship between Diet Quality, Physical Activity and Health-Related Quality of Life in Older Adults: Findings from 2007-2014 National Health and Nutrition Examination Survey

BACKGROUND

A growing body of research shows that diet quality and physical activity (PA) are associated with health-related quality of life (HRQOL). However, no study to date has assessed this association using the Healthy Eating Index-2015 as a measure of diet quality. Furthermore, few studies have examined the association between PA dose and HRQOL among a nationally representative sample of older adults.

OBJECTIVES

To investigate the relationship between diet quality, physical activity, and HRQOL.

DESIGN

A cross-sectional analysis was conducted using data obtained from 5,311 adults aged 60+ years who took part in the National Health and Nutrition Examination Survey between 2007 and 2014.

MEASUREMENTS

HRQOL was assessed by general health status, and number of physically unhealthy days, mentally unhealthy days, and inactive days in past 30 days. Diet quality was assessed by the Healthy Eating Index-2015 using data generated by two 24-hour dietary recalls. PA was measured by the Global Physical Activity Questionnaire. Multivariate logistic/or linear regression models were used to examine the association between diet quality, PA and HRQOL controlling for confounders and accounting for complex sampling.

RESULTS

Approximately half of the participants (55.2%) were women, 45.1% met current PA recommendations, 65% had less healthful diets according to the Healthy Eating Index-2015. Diet quality was associated with HROQL. For every 1-point diet quality score increase, the likelihood of respondents rating their general health as being excellent/good increased by 3% (OR=1.03, 95%CI: 1.02, 1.04), and number of inactive days (β =-0.03, 95%CI: -0.05, 0.00) and mental unhealthy days (β =-0.03, 95%CI: -0.05, -0.01) declined by 0.03 days. PA was associated with all HROQL measures and respondents with high PA levels reported better general health (OR=3.53, 95%CI: 2.69, 4.63), fewer inactive days (β =-1.53, 95%CI: -2.11, -0.95), fewer physical unhealthy days (β =-1.88, 95%CI: -2.74, -1.02) than individuals with low PA levels but not fewer mentally unhealthy days.

CONCLUSIONS

Among older adults in this study, eating a healthier diet and being physically active were associated with better general health and reporting fewer physical unhealthy days and inactive days. Study results provide valuable information that could inform policies, programs and interventions designed to improve HRQOL in older adults and reduce potentially preventable health disparities.

Prechallenge antibodies: moderators of infection rate, signs, and symptoms in adults experimentally challenged with rhinovirus type 39

This study determined the influence of serum neutralizing antibody titers on infection rate, symptom manifestations, and provoked signs and pathophysiologies in adults experimentally exposed to rhinovirus type 39 (RV-39). Antibody status was determined for 151 healthy volunteers who were then cloistered in a hotel for 6 days. At the end of the first cloister day, the volunteers were challenged with RV-39 in a median tissue culture infective dose of 100. On each of the 6 days, a nasal examination was performed, symptoms were scored, and objective tests of nasal mucociliary function, nasal airway patency, secretion production, and middle ear pressures were completed. Both subjects and investigators were blinded to the prechallenge serum homotypic antibody titers of the subjects. Four subjects presented with a wild virus and were excluded from the analysis. Of the 147 included subjects, prechallenge serum antibody titers to RV-39 were low (under 2) in 56 subjects, intermediate (2 to 8) in 51 subjects, and high (above 16) in 40 subjects. The high-titer group was significantly different from the low-titer group with respect to viral shedding, symptom load, subjective extent of illness, and secretion production, as well as in the frequency of subjects with abnormal nasal mucociliary clearance and positive middle ear pressures. The study results document that for experimental RV-39 exposure, high levels of homotypic serum neutralizing antibody titers are associated with protection from infection and a lessened degree of disease expression, but not with a reduction of otologic complications.

Inactivation of Bacillus cereus beta-lactamase I by 6 beta-bromopenicillanic acid: kinetics

The kinetics of the inactivation of Bacillus cereus beta-lactamase I by 6 beta-bromopenicillanic acid are described. Loss of beta-lactamase activity is accompanied by a decrease in protein fluorescence, by the appearance of a protein-bound chromophore at 326 nm, and by loss of tritium from 6 alpha-[3H]-6 beta-bromopenicillanic acid. It is shown that all of the above changes probably have the same rate-determining step. The inactivation reaction is competitively inhibited by cephalosporin C, a competitive inhibitor of this enzyme, and by covalently bound clavulanic acid, suggesting that 6 beta-bromopenicillanic acid reacts directly with the beta-lactamase active site. It is proposed that this inhibitor reacts initially as a normal substrate and that the rate-determining step of the inactivation is acylation of the enzyme. A rapid irreversible inactivation reaction rather than normal hydrolysis of the acyl-enzyme then follows acylation; 6 beta-bromopenicillanic acid is thus a suicide substrate.

Interferon-alpha prevents endotoxin-induced mortality in mice

Endotoxins, the lipopolysaccharide (LPS) moieties on the bacterial cell wall, cause many of the pathological features of Gram-negative septicemia. Tumor necrosis factor (TNF), primarily a product of monocyte/macrophages, has been shown to mediate many of the pathophysiological effects of endotoxin. Kupffer cells, the largest macrophage population in the body, release TNF when stimulated by LPS in vitro. A recombinant human hybrid interferon-alpha A/D (rIFN-alpha) markedly inhibited this LPS-elicited TNF production by Kupffer cells. The effects of rIFN-alpha were further tested in C57BL/6 mice receiving a lethal dose (400 micrograms/mouse) of LPS. All LPS-treated mice died within 2 days. Pretreatment with rIFN-alpha 1 h before LPS challenge improved the survival at 3 days to 22% (5/23, p < 0.04). In contrast, rIFN-alpha was more effective when administered 20 min after LPS injection, increasing the survival rate to 81% (13/16, p < 0.0001). TNF mRNA expression in the liver and spleen 50 min after LPS challenge, and plasma TNF 1.5 h after LPS were also reduced by either pretreatment or post-treatment with rIFN-alpha. Subsequently, experiments were carried out to test the efficacy of delayed rIFN-alpha treatment. A significant protective effect was still apparent when rIFN-alpha was administered 6, 10 and even 14 h (81%, 62% and 28% survival, respectively) after LPS challenge when serum TNF levels had already returned to near baseline. These experimental results suggest that rIFN-alpha might have a therapeutic potential for the prevention and treatment of the deleterious effects associated with endotoxemia besides mechanisms initially blocking TNF production.

High-performance liquid chromatographic analysis of synthetic peptides using derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate

A series of synthetic prothrombin leader sequences (ANKGFLEEX), each having a different C-terminal amino acid, was derivatized with the novel fluorescent-derivatizing agent 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate and analyzed by HPLC. Essentially quantitative yields of derivatized peptides could be routinely obtained with a fast, simple derivatizing procedure. The response was linear over a concentration range of 0.176 to 88.0 nM. Peptides labeled with this highly sensitive derivatizing agent exhibited a mass detection limit in the femtomole range and a concentration detection limit in the picomolar range. Amino acid content of hydrolyzed peptides was carried out using the same reagent in order to evaluate the amino acid composition and to detect any deletion sequences.

Natural antitumor defense system of the murine liver

Murine nonparenchymal liver cells from various genetic strains isolated by collagenase digestion and differential sedimentation contain both lymphocytes and macrophages. Nonparenchymal liver cells as well as spleen cells, mononuclear blood cells, and peritoneal exudate cells from C3HeB/FeJ mice were tested for natural cytotoxicity against YAC-1 (sensitive to NK cells) and P815 (resistant to NK cells) tumor cell lines. Resident peritoneal exudate cells exerted no cytotoxicity against either tumor cell, whereas spleen and mononuclear blood cells lysed only YAC-1. In contrast, nonparenchymal liver cells lysed both YAC-1(4 h) and P815 (18 h) tumor cells. Treatment of nonparenchymal liver cells with anti-asialo GM1 and complement abolished the antitumor activity against both tumor cell lines but not the phagocytic activity. Nonadherent nonparenchymal liver cells exerted greater cytotoxicity against YAC-1 tumor cells but little cytotoxicity against P815 tumor cells when compared with unfractionated cells. Adherent nonparenchymal liver cells (macrophages) from untreated mice exerted no antitumor activity against either tumor cell. In contrast, adherent nonparenchymal liver cells from Corynebacerium parvum treated mice were directly cytotoxic to P815 tumor cells. Spleen cells that are normally not cytotoxic to P815 tumor cells (18 h) became cytotoxic when mixed with adherent nonparenchymal liver cells from untreated mice. These results indicate that the tumoricidal effector cell in nonparenchymal liver cells from untreated mice appears to be the NK cell. Apparently, murine liver macrophages from untreated mice do not have tumoricidal activity per se but can "activate" NK cells to kill tumor cells normally resistant to NK cells.

Glycoprotein characteristics of the sodium channel saxitoxin-binding component from mammalian sarcolemma

The saxitoxin-binding component of the excitable membrane sodium channel exhibits glycoprotein characteristics as evidenced by its specific interaction with various agarose-immobilized lectins. The detergent-solubilized saxitoxin-binding component interacts quantitatively with immobilized wheat germ agglutinin and concanavalin A and fractionally with immobilized Lens culinaris hemagglutinin and Ricinus communis agglutinin. These lectins preferentially bind N-acetylglucosamine and sialic acid (wheat germ agglutinin), mannose (concanavalin A and Lens cunilaris) and galactose (Ricinus communis). Removal of terminal sialic acid residues by neuraminidase markedly decreases binding to immobilized wheat germ agglutinin but uncovers sites capable of interacting with lectins specific for galactose and N-acetylgalactosamine. beta-N-acetylglucosaminidase, an exoglycosidase, has no effect on the binding of the channel protein to wheat germ agglutinin. Similarly, phospholipase C has no effect on binding of the solubilized toxin binding component to this lectin. Neither wheat germ agglutinin nor concanavalin A free in solution alters the number of toxin binding sites or their affinity for toxin. The sodium channel saxitoxin-binding component to wheat germ agglutinin. Similarly, phospholipase C has no effect on binding of the solubilized toxin binding component to this lectin. Neither wheat germ agglutinin nor concanavalin A free in solution alters the number of toxin binding sites or their affinity for toxin. The sodium channel saxitoxin-binding component to wheat germ agglutinin. Similarly, phospholipase C has no effect on binding of the solubilized toxin binding component to this lectin. Neither wheat germ agglutinin nor concanavalin A free in solution alters the number of toxin binding sites or their affinity for toxin. The sodium channel saxitoxin-binding component appears to be a glycoprotein containing terminal sialic acid residues and internal mannose, galactose, N-acetylglucosamine, and N-acetylgalactosamine residues. The toxin binding site is spatially separated from the binding sites for the lectins studied. The effect of these sugar moieties must be considered when evaluating the biophysical parameters of the sodium channel.

Low density lipoproteins and Lovastatin modulate the organ-specific transendothelial migration of primary and metastatic human colon adenocarcinoma cell lines in vitro

Tumor cell arrest and tumor migration are two of the critical steps in the metastatic cascade. We hypothesized that these steps may be facilitated by the low density lipoprotein (LDL)-induced activation of microvessel endothelial cells (MVEC). The purpose of our study was to investigate the biological effects of an LDL-enriched milieu and the effects of the anticholesterol drug Lovastatin on metastatic behavior. The SW480 and SW620 are primary and metastatic human colonic adenocarcinoma cell lines derived from the same patient. We investigated the effect of LDL on adhesion and migration of the two tumor cell lines across human brain, lung, liver and dermal endothelial monolayers. Adhesion and migration assays were done before and after pretreatment of the MVEC or tumor cells with LDL (100 microg/ml) for 24 h. Although metastatic SW620 cells were more adherent to MVEC compared with primary SW480 cells, LDL pretreatment of SW480 and SW620 cells did not affect tumor cell adhesion to MVEC. In contrast, tumor cell migration was significantly increased across endothelial monolayers when MVEC were pretreated with LDL. Transendothelial cell migration was not significantly affected by pretreatment of the tumor cells with LDL. Lovastatin is an inhibitor of HMG-CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis. It has been shown to have anti-tumor activity in vitro. We investigated the effect of Lovastatin on tumor cell kinetics and tumor cell migration across MVEC. Growth curves and migration assays were done before and after pretreatment of the tumor cells with Lovastatin (30 microg/ml). Migration assays were also done after treatment of unstimulated or LDL-stimulated MVEC (100 microg/ml) for 24 h with Lovastatin. Lovastatin inhibited the in vitro growth of the metastatic SW620 cell line to a greater extent than the invasive SW480E cell line. On the other hand, pretreatment of tumor cells with Lovastatin (30 microg/ml) did not suppress transendothelial tumor cell migration of tumor cells. Finally, Lovastatin given to mice effectively suppressed the number of MCA-26 tumor colonies in the liver of Balb/c mice compared with untreated mice.

Stent-guided sphincterotomy

Performing sphincterotomy when either Billroth II gastrectomy or complicated periampullary diverticula are present may increase the risk of complications. In addition a sphincterotomy on the main pancreatic sphincter or the papilla of Santorini presents complicated problems. Stent-guided sphincterotomy has been utilized in 229 patients presenting to our institution from 1983 through 1992. They were performed in 67 patients who had undergone Billroth II gastrectomy, 23 with periampullary diverticula, 57 with pancreas divisum, and 82 with a history of recurrent pancreatitis. To prevent ductal injury or perforation, a stent is first inserted into the biliary or pancreatic duct to guide the sphincterotomy incision. The sphincterotomy is performed using electrocautery current delivered through a "needle knife" sphincterotome. Pancreatitis occurred in 19 patients (8.3%). It was mild in 17 and moderate in two patients. One patient experienced severe hemorrhage requiring surgery. No mortality or perforations occurred. The stent-guided needle knife sphincterotomy approach is an effective technique. It has a low complication rate even in these difficult anatomic conditions. It assures that the incision precisely follows the duct when performing pancreatic sphincterotomy.