Prediction of adverse cardiovascular events in children using artificial intelligence-based electrocardiogram

BACKGROUND

Convolutional neural networks (CNNs) have emerged as a novel method for evaluating heart failure (HF) in adult electrocardiograms (ECGs). However, such CNNs are not applicable to pediatric HF, where abnormal anatomy of congenital heart defects plays an important role. ECG-based CNNs reflecting neurohormonal activation (NHA) may be a useful marker of pediatric HF. This study aimed to develop and validate an ECG-derived marker of pediatric HF that reflects the risk of future cardiovascular events.

METHODS

Based on 21,378 ECGs from 8324 children, a CNN was trained using B-type natriuretic peptide (BNP) and the occurrence of major adverse cardiovascular events (MACEs). The output of the model, or the electrical heart failure indicator (EHFI), was compared with the BNP regarding its ability to predict MACEs in 813 ECGs from 295 children.

RESULTS

EHFI achieved a better area under the curve than BNP in predicting MACEs within 180 days (0.826 versus 0.691, p = 0.03). On Cox univariable analyses, both EHFI and BNP were significantly associated with MACE (log10 EHFI: hazard ratio [HR] = 16.5, p < 0.005 and log10 BNP: HR = 4.4, p < 0.005). The time-dependent average precisions of EHFI in predicting MACEs were 32.4%-67.9% and 1.6-7.5-fold higher than those of BNP in the early period. Additionally, the MACE rate increased monotonically with EHFI, whereas the rate peaked at approximately 100 pg/mL of BNP and decreased in the higher range.

CONCLUSIONS

ECG-derived CNN is a novel marker of HF with different prognostic potential from BNP. CNN-based ECG analysis may provide a new guide for assessing pediatric HF.

Removal of central venous catheter using Evolution® Rotating Dilator

We experienced the first case of a difficult-to-extract central venous catheter removed with a pacemaker lead removal system: a 14-year-old boy with Hirschsprung's disease who had repeated catheter infections that could not be removed by traction. Because the catheter lumen was occluded, a suture was tied around the end of the catheter and the catheter was removed with a rotating dilator.

Hemodynamic simulation of complete transposition of the great arteries for optimal treatment strategies based on its circulatory physiology

Our study aimed to elucidate the role of different shunts and provide novel insights into optimal treatment approaches for complete transposition of the great arteries (TGA), which is characterized by unique and complicated circulatory dynamics. We constructed a computational cardiovascular TGA model and manipulated cardiovascular parameters, such as atrial septal defect (ASD) and patent ductus arteriosus (PDA) sizes, to quantify their effects on oxygenation and hemodynamics. In addition, ASD flow patterns were investigated as innovative indications for balloon atrial septostomy (BAS). Our model of TGA with an intact ventricular septum (TGA-IVS) showed that a large ASD can achieve sufficient mixing for survival without PDA, and the presence of PDA is detrimental to oxygen delivery. A treatment strategy for TGA-IVS that enlarges the ASD as much as possible by BAS and PDA closure would be desirable. In TGA with a ventricular septal defect (TGA-VSD), the VSD allows for higher oxygenation and reduces the detrimental effects of PDA on systemic circulation. In TGA-VSD, both strategies of enlarging the ASD by BAS with a closed PDA and adjusting the PDA in response to pulmonary vascular resistance (PVR) reduction without BAS may be effective. The simulated ASD flow patterns showed that the sharp peak left-to-right flow pattern in systole (σ-wave) reflected the hemodynamically significant ASD size, independent of PDA, VSD, and PVR. The ASD flow pattern visualized by Doppler echocardiography provides clinical insights into the significance of an ASD and indications for BAS, which are not readily apparent through morphological assessment.NEW & NOTEWORTHY Complete transposition of the great arteries (TGA) represents complex and unique circulation that is dependent on blood mixing through multiple interacting shunts. Consequently, the role of each shunt and the treatment strategy remain unclear. We developed a mathematical model of TGA circulation, revealing the significant influence of atrial septal defect (ASD) on oxygenation and hemodynamics. The blood flow pattern through the ASD reflects its hemodynamic impact and helps determine treatment strategies.

Takotsubo cardiomyopathy in a child with single-ventricle disease

Takotsubo cardiomyopathy, a disease that causes transient contractile abnormalities mainly in the left ventricular apex, is rarely reported in children, especially in those with single-ventricle disease. A 4-year-old boy with a single right ventricle was transferred to our hospital following a severe seizure and was diagnosed with takotsubo cardiomyopathy by echocardiography. His cardiac function improved; however, he developed hypoxic-ischemic encephalopathy.

Complete dechlorination of tetrachloroethylene by use of an anaerobic Clostridium bifermentans DPH-1 and zero-valent iron

A laboratory test was conducted to examine the combined effect of an anaerobic Clostridium bifermentans DPH-1 and addition of zero-valent iron (Fe0) on the reductive dechlorination of tetrachloroethylene (PCE). In addition, the dechlorination of cis-1,2-dichloroethylene (cDCE) produced from PCE was examined using Fe0. The cDCE produced was completely dechlorinated to non-toxic end products, mostly, ethylene by a subsequent chemical reductive process. Production of ethylene was dramatically increased with increase of initial cDCE concentration in the range of 10.3 microM to 928 microM (1.0-90 mg l(-1)) and the velocity constant was calculated to be 0.38 day(-1). On the other hand, the combined use of strain DPH-1 and Fe0 showed the most significant effect on the initial PCE dechlorination, but cohesion of Fe0 was found to inhibit the dechlorination rate of PCE. It is thought that phosphoric acid iron contained in a medium forms film on the surface of iron particle, so oxidation of iron is inhibited.

Expression of xyrA gene encoding for D-Xylose reductase of Candida tropicalis and production of xylitol in Escherichia coli

The D-Xylose reductase (XR) gene (xyrA) of Candida tropicalis IFO 0618 was expressed in Escherichia coli JM109. The enzymatic properties of each recombinant XR such as the Km value for D-xylose and NADPH, the substrate specificity for other sugars and the optimal pH were essentially the same as those of the corresponding enzyme of C. tropicalis. The recombinant XR was more heat-stable than C. tropicalis XR at 60 degrees C. E. coli, expressing the xyrA gene, successfully converted D-xylose to xylitol. When D-xylose (50 g/l) and D-glucose (5 g/l) were added to IPTG-induced cells, 13.3 g/l of xylitol was produced during 20 h of cultivation.

Transport of Clostridium bifermentans DPH-1 through the laboratory column can be explained by two-region model for bioremediation

Transport of Clostridium bifermentans DPH-1 was characterized from laboratory-made column tests using fully saturated Toyoura sand. The conventional transport models were fitted to the column test results to investigate the applicability of prediction and assessment of bacterial transport in actual subsurface or ground water. Laboratory column tests confirmed that the transport characteristics of Clostridium bifermentans DPH-1 in activating tetrachloroethylene dechlorination could be described by mobile-immobile two-region model. The parameters of two-region model i.e. peclet number, retardation factor, fraction rate of mobile water and stanton number were characterized by fitting results. These parameters were also justified by a verification experiment. Two-region model parameters suggested that bacterial injection into the ground at a large concentration is difficult for rehabilitation of widely dispersed contaminated ground water.

Lactobacillus casei strain Shirota suppresses serum immunoglobulin E and immunoglobulin G1 responses and systemic anaphylaxis in a food allergy model

BACKGROUND

Our previous study using allergen-sensitized murine splenocyte cultures has shown that Lactobacillus casei strain Shirota (LcS), a lactic acid bacterium widely used as a starter for fermented milk products, suppresses IgE production through promoting a dominant Th1-type response mediated by IL-12 induction.

OBJECTIVE

We tried to evaluate the ability of LcS to suppress both IgE response and allergic reactions in vivo using a food allergy model with ovalbumin-specific T cell receptor transgenic (OVA-TCR-Tg) mice.

METHODS

The ability of heat-killed LcS to induce IL-12 in serum was tested. OVA-TCR-Tg mice were fed a diet containing OVA for 4 weeks and injected with LcS intraperitoneally three times in the first week of this period. Cytokine and antibody secretion by splenocytes, and serum IgE and IgG1 responses were examined. The inhibitory effect of LcS on systemic anaphylaxis induced by intravenous challenge of OVA-fed OVA-TCR-Tg mice with OVA was also tested.

RESULTS

Intraperitoneal injection of LcS induced an IL-12 response in the serum of OVA-TCR-Tg mice. In the food allergy model, LcS administration skewed the pattern of cytokine production by splenocytes toward Th1 dominance, and suppressed IgE and IgG1 secretion by splenocytes. The ability of LcS to modulate cytokine production was blocked by anti-IL-12 antibody treatment. LcS also inhibited serum OVA-specific IgE and IgG1 responses and diminished systemic anaphylaxis.

CONCLUSION

LcS administration suppresses IgE and IgG1 responses and systemic allergic reactions in a food allergy model, suggesting a possible use of this lactic acid bacterium in preventing food allergy.

The production of D-xylose by enzymatic hydrolysis of agricultural wastes

Agricultural wastes, rich in D-xylose content, were hydrolyzed using the mixed crude enzymes produced by Penicillium sp. AHT-1 and Rhizomucor pusillus HHT-1. Shells of pistachio, peanut, walnut, chestnut, barley brans and sunflower seed peels, were used as raw or pretreated forms. Pretreatment was performed by milling or steam explosion. Enzymatic hydrolysis after steam explosion was more effective than milling processing. More than 13 g of D-xylose was produced from 100 g of milled pistachio shells, walnut shells, sunflower seed peels and peanut shells (less than 0.5 mm size) by the action of mixed enzyme solutions. A maximum of 36 g of D-xylose was produced from 100 g of milled pistachio shells when mixed enzyme solution, containing 3,000 U and 33 U per g of substrate with xylanase and beta-xyosidase activities, respectively, was applied. The ratio of the enzymatic hydrolysis as compared to acid hydrolysis in this finding was 100%.

Physicochemical properties of a novel alpha-L-arabinofuranosidase from Rhizomucor pusillus HHT-1

The zygomycete fungus Rhizomucor pusillus HHT-1, cultured on L(+)arabinose as a sole carbon source, produced extracellular alpha-L-arabinofuranosidase. The enzyme was purified by (NH4)2SO4 fractionation, gel filtration, and ion exchange chromatography. The molecular mass of this monomeric enzyme was 88 kDa. The native enzyme had a pI of 4.2 and displayed a pH optimum and stability of 4.0 and 7.0-10.0, respectively. The temperature optimum was 65 degrees C, and it was stable up to 70 degrees C. The Km and Vmax for p-nitrophenyl alpha-L-arabinofuranoside were 0.59 mM and 387 micromol x min(-1) x mg(-1) protein, respectively. Activity was not stimulated by metal cofactors. The N-terminal amino acid sequence did not show any similarity to other arabinofuranosidases. Higher hydrolytic activity was recorded with pnitrophenyl alpha-L-arabinofuranoside, arabinotriose, and sugar beet arabinan; lower hydrolytic activity was recorded with oat-spelt xylan and arabinogalactan, indicating specificity for the low molecular mass L(+)-arabinose containing oligosaccharides with furanoside configuration.

Small-diameter compliant arterial graft prosthesis: Design concept of coaxial double tubular graft and its fabrication

To minimize compliance mismatch between native artery and arterial graft prosthesis over the entire pressure regions, we proposed a coaxial double tubular artificial graft which consists of an enhanced compliant inner tube and a less compliant outer tube, both of which were fabricated using well-controlled multiply micropored segmented polyurethane (SPU) films. Double tubular grafts were coaxially assembled by inserting the inner tube into the outer tube. First, the pressure-diameter (P-D) relationship of canine common carotid arteries, which exhibited a "J" curve, was determined as a targeted artery. Two determinant variables, the pressure-induced distensibility of each tube and the intertubular space distance, were defined and formulated in several models of coaxial double tubular SPU grafts, which had various intertubular space distances, micropore densities, and wall thicknesses. The distensibility of the inner tube determined the distensibility in the low-pressure regions, which was adjusted using wall thickness and microporosity. Thinner films with higher porosities resulted in a high pressure-induced distensibility. On the other hand, a low pressure-induced distensibility in the high-pressure regions was realized using an outer tube with a thicker wall and lower microporosity. The transition point from low- to high-pressure regions was determined by the intertubular distance using the theoretical values. On the basis of these results, we presented a prototype model of a coaxial double tubular graft that exhibited well-matched compliance with canine carotid artery.

In vitro dehalogenation of tetrachloroethylene (PCE) by cell-free extracts of Clostridium bifermentans DPH-1

Cell-free extracts of Clostridium bifermentans DPH-1 catalyzed tetrachloroethylene (PCE) dechlorination. PCE degradation was stimulated by addition of a variety of electron donors. Ethanol (0.61 mM) was the most effective electron donor for PCE dechlorination. Maximum activity was recorded at 30 degrees C and pH 7.5. Addition of NADH as a cofactor stimulated enzymatic activity but the activity was not stimulated by addition of metal ions. When the cell-free enzyme extract was incubated in the presence of titanium citrate as a reducing agent, the dehalogenase was rapidly inactivated by propyl iodide (0.5 mM). The activity of propyliodide-reacted enzyme was restored by illumination with a 250 W lamp. The dehalogenase activity was also inhibited by cyanide. The substrate spectrum of activity included trichloroethylene (TCE), cis-1,2-dichloroethylene (cDCE), trans-dichloroethylene, 1,1-dichloroethylene, 1,2-dichloroethane, and 1,1,2-trichloroethane. The highest rate of degradation of the chlorinated aliphatic compounds was achieved with PCE, and PCE was principally degraded via TCE to cDCE. Results indicate that the dehalogenase could play a vital role in the breakdown of PCE as well as a variety of other chlorinated aliphatic compounds.

Purification, cloning, and sequencing of an enzyme mediating the reductive dechlorination of tetrachloroethylene (PCE) from Clostridium bifermentans DPH-1

An enzyme mediating the reductive dechlorination of tetrachloroethylene (PCE) from cell-free extracts of Clostridium bifermentans DPH-1 was purified, cloned, and sequenced. The enzyme catalyzed the reductive dechlorination of PCE to cis-1,2-dichloroethylene via trichloroethylene, at a Vmax and Km of 73 nmol/mg protein and 12 microM, respectively. Maximal activity was recorded at 35 degrees C and pH 7.5. Enzymatic activity was independent of metal ions but was oxygen sensitive. A mixture of propyl iodide and titanium citrate caused a light-reversible inhibition of enzymatic activity suggesting the involvement of a corrinoid cofactor. The molecular mass of the native enzyme was estimated to be approximately 70 kDa. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption ionization-time of flight/mass spectrometry (MALDI-TOF/MS) revealed molecular masses of approximately 35 kDa and 35.7 kDa, respectively. A broad spectrum of chlorinated aliphatic compounds (PCE, trichloroethylene, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1,1-dichloroethylene, 1,2-dichloropropane, and 1,1,2-trichloroethane) was degraded. With degenerate primers designed from the N-terminal sequence (27 amino acid residues), a partial sequence (81 bp) of the encoding gene was amplified by polymerase chain reaction (PCR) and sequenced. Southern analysis of C. bifermentans genomic DNA using the PCR product as a probe revealed restriction fragment bands. A 5.0 kb ClaI fragment, harboring the relevant gene (designated pceC) was cloned (pDEHAL5) and the complete nucleotide sequence of pceC was determined. The gene showed homology mainly with microbial membrane proteins and no homology with any known dehalogenase, suggesting a distinct PCE dehalogenase.

Methanocalculus pumilus sp. nov., a heavy-metal-tolerant methanogen isolated from a waste-disposal site

A mesophilic hydrogenotrophic methanogen, strain MHT-1T, was isolated from the leachate of a sea-based site for solid waste disposal (the port of Osaka, Japan). Strain MHT-1T was found to be an irregular coccus and was able to use H2/CO2 and formate as energy sources. Acetate was required for growth. The optimum temperature and pH for growth were 35 degrees C and 6.5-7.5, respectively. Strain MHT-1T was resistant to high concentrations of several heavy metals such as CdCl2 and CuSO4. The G+C content of the DNA was 51.9 mol%. Analysis of the 16S rRNA gene revealed that the isolate was a member of the genus Methanocalculus but distinct from its nearest neighbour, Methanocalculus halotolerans, there being a sequence similarity of 98.9%. DNA-DNA hybridization analysis revealed 51% relatedness with the DNA of M. halotolerans strain SEBR 4845T. The optimum NaCl concentration was 1.0%, whereas the optimum in M. halotolerans was 5.0%. A new species, Methanocalculus pumilus, is proposed for strain MHT-1T. The type strain is MHT-1T (= DSM 12632T = JCM 10627T).

Role of the DExH motif of the Japanese encephalitis virus and hepatitis C virus NS3 proteins in the ATPase and RNA helicase activities

The role of the conserved DExH motif of the Japanese encephalitis virus (JEV) NS3 protein in the ATPase and RNA helicase activities was compared with that of the hepatitis C virus (HCV) NS3 protein. In the DExH motif of JEV NS3, Asp-285 and Glu-286 were essential for both ATPase and RNA helicase activities. Cys-287 was critical for the RNA helicase activity of JEV NS3 but not for ATPase activity. A His-288-to-Ala substitution in the DExH motif of HCV NS3 resulted in an increase in ATPase activity which was suppressed by poly(U). In contrast, alanine substitution at the same site in JEV NS3 did not increase basal ATPase activity which remained to be stimulated by poly(U). Thus, the mutational effect at His in motif II was different in the HCV and JEV NS3 proteins. Mutagenesis at His-288 of JEV NS3 revealed that His was the most preferable amino acid for ATPase activity and Ala, Gly, Asn, Gln, Ser, or Arg could partly substitute for it. However, any other mutation at His-288 completely disrupted the RNA helicase activity of JEV NS3. The results suggest that Cys-287 and His-288 are essential residues especially for the RNA helicase activity of JEV NS3 and the ATPase and helicase activities are separable enzymatic functions.

Serum IgE response to orally ingested antigen: a novel IgE response model with allergen-specific T-cell receptor transgenic mice

BACKGROUND

The mechanism by which orally ingested allergens elicit an IgE response remains unclear because there are few animal models available for investigation of this response.

OBJECTIVE

We tried to develop a murine model suitable for investigation of the IgE response to orally ingested allergens, which would allow us to identify T cells that could promote IgE production.

METHODS

Ovalbumin (OVA)-specific T-cell receptor transgenic mice were fed a diet containing OVA, and both the serum antibody response and cytokine production by splenocytes were examined.

RESULTS

Oral administration of OVA to transgenic mice led to an increase in the levels of both antigen-specific IgE and total IgE in the sera. Subsequent intravenous challenge of OVA-fed transgenic mice with OVA resulted in anaphylactic shock. Analysis of cytokine production by splenocytes revealed that high IL-4-producing T cells appeared in the spleen 1 week after the start of feeding the OVA diet. T cells from these mice were found to promote IgE secretion by BALB/c B cells in vitro. This helper activity and the levels of IL-4 secretion were diminished after long-term feeding. These findings suggest the possibility that the orally ingested antigen elicited a response by a subpopulation of T cells that produce high levels of T(H2)-type cytokines and that promote IgE secretion, and these same T cells were tolerized by the orally ingested antigen.

CONCLUSION

This experimental model with transgenic mice may be a useful tool for further studies of the cellular and molecular mechanisms of the T-cell and IgE responses to orally ingested antigens.

Development of a xylitol biosensor composed of xylitol dehydrogenase and diaphorase

In preparation for the development of a xylitol biosensor, the xylitol dehydrogenase of Candida tropicalis IFO 0618 was partially purified and characterized. The optimal pH and temperature of the xylitol dehydrogenase were pH 8.0 and 50 degrees C, respectively. Of the various alcohols tested, xylitol was the most rapidly oxidized, with sorbitol and ribitol being reduced at 65% and 58% of the xylitol rate. The enzyme was completely inactive on arabitol, xylose, glucose, glycerol, and ethanol. The enzyme's xylitol oxidation favored the use of NAD+ (7.9 U/mg) over NADP+ (0.2 U/mg) as electron acceptor, while the reverse reaction, D-xylulose reduction, favored NADPH (7.7 U/mg) over NADH (0.2 U/mg) as electron donor. The K(m) values for xylitol and NAD+ were 49.8 mM and 38.2 microM, respectively. For the generation of the xylitol biosensor, the above xylitol dehydrogenase and a diaphorase were immobilized on bromocyan-activated sephallose. The gel was then attached on a dissolved oxygen electrode. In the presence of vitamin K3, NAD+ and phosphate buffer, the biosensor recorded a linear response to xylitol concentration up to 3 mM. The reaction was stable after 15 min. When the biosensor was applied to a flow injection system, optimal operation pH and temperature were 8.0 and 30 degrees C, respectively. The strengths and limitations of the xylitol biosensor are its high affinity for NAD+, slow reaction time, narrow linear range of detection, and moderate affinity for xylitol.

Identification and characterization of the RNA helicase activity of Japanese encephalitis virus NS3 protein

The NS3 protein of Japanese encephalitis virus (JEV) contains motifs typical of RNA helicase/NTPase but no RNA helicase activity has been reported for this protein. To identify and characterize the RNA helicase activity of JEV NS3, a truncated form of the protein with a His-tag was expressed in Escherichia coli and purified. The purified JEV NS3 protein showed an RNA helicase activity, which was dependent on divalent cations and ATP. An Asp-285-to-Ala substitution in motif II of the JEV NS3 protein abolished the ATPase and RNA helicase activities. These results indicate that the C-terminal 457 residues are sufficient to exhibit the RNA helicase activity of JEV NS3.

Isolation and characterization of a tetrachloroethylene dechlorinating bacterium, Clostridium bifermentans DPH-1

A tetrachloroethylene (PCE)-degrading gram-positive, endospore forming, anaerobic bacterium, strain DPH-1, was isolated from a contaminated site. The organism was identified as Clostridium bifermentans by 16S rRNA gene sequence analysis and based on its physiological characteristics. Strain DPH-1 could dechlorinate high concentrations of PCE (0.9 mM), via trichloroethylene (TCE) to cis-1,2-dichloroethylene (cDCE) at a rate of 0.43 micromol/h.mg protein, as well as a number of other halogenated aliphatic compounds.

Effect of heavy metals on the growth of a methanogen in pure culture and coculture with a sulfate-reducing bacterium

The sensitivity of a methanogen and sulfate-reducing bacterium isolated from a sea-based landfill site to Cd2+ and Cu2+ was studied. Methanogens and sulfate-reducing bacteria in leachates of the waste disposal site were enumerated using the MPN method. Methanobacterium thermoautotrophicum KHT-2, isolated from the leachate, could not grow at 0.5 mM Cd2+ or 1.0 mM Cu2+. Desulfotomaculum sp. RHT-3, isolated from the same leachate, was able to insolubilize 3.0 mM Cd2+ or 2.0 mM Cu2+ by production of hydrogen sulfide. When strains KHT-2 and RHT-3 were cultured together in the presence of the heavy metals, strain KHT-2 could grow at high heavy metal concentrations after insolubilization of the metals by strain RHT-3.

Lactobacillus casei inhibits antigen-induced IgE secretion through regulation of cytokine production in murine splenocyte cultures

BACKGROUND

Lactobacillus casei is a nonpathogenic gram-positive bacterium widely used in dairy products and has been shown to enhance the cellular immunity of the host.

METHODS

To examine the inhibitory effect of L. casei on IgE production, splenocytes obtained from ovalbumin (OVA)-primed BALB/c mice were restimulated in vitro with the same antigen in the presence of heat-killed L. casei. The effect of this bacterium on T helper (Th) phenotype development was also examined with naive T cells from OVA-specific T cell receptor-transgenic mice.

RESULTS

L. casei induced IFN-gamma, but inhibited IL-4 and IL-5 secretion, and markedly suppressed total and antigen-specific IgE secretion by OVA-stimulated splenocytes. The inhibitory effect of L. casei on IgE, IL-4, and IL-5 production was partially abrogated by addition of neutralizing antibody to IFN-gamma. Augmented IL-12 production was also observed in the cell cultures containing L. casei, and anti-IL-12 monoclonal antibody completely restored the IgE, IL-4, and IL-5 production to the control levels. The IL-12 augmentation by L. casei was macrophage-dependent. The Th cell development assay showed the ability of L. casei to induce Th1 development preferentially. This effect was also completely blocked by anti-IL-12 antibody.

CONCLUSIONS

This is the first demonstration that a nonpathogenic microorganism, L. casei, can inhibit antigen-induced IgE production through induction of IL-12 secretion by macrophages. The findings suggest a potential use of this organism in preventing IgE-mediated allergy.

Inhibition of Escherichia coli heat-labile enterotoxin by an amino carbonyl product, lactose-alpha-lactalbumin

The inhibition by lactose-alpha-lactalbumin amino carbonyl product of Escherichia coli heat-labile enterotoxin was studied by GM1-ELISA and by assay with CHO-K1 cells. The product dose-dependently inhibited the binding of the enterotoxin to GM1 ganglioside and decreased the morphological change of CHO-K1 cells caused by this toxin. The results suggest that this product may be a receptor analogue in the intestine.

Characterization by Western blotting of mouse intestinal glycoproteins bound by Escherichia coli heat-labile enterotoxin type I

Escherichia coli heat-labile enterotoxin type I (LT-I)-binding galactoproteins, which were not recognized by cholera toxin, were detected in intestinal epithelial cells of BALB/c mouse by Western blotting. Inhibitory studies using lectins and modifications of sugar chain suggest that LT-I recognizes certain mucin-type sugar chains containing the terminal Galbeta1-3GalNAc sugar sequence in the galactoproteins. The terminal sugar sequence is identical to that of GM1 ganglioside, the well-documented functional receptor for LT-I.

Mathematical simulation of unidirectional tissue formation: in vitro transanastomotic endothelialization model

In vitro transanastomotic endothelialization was studied using a mathematical model with the Fisher equation. The Fisher equation is a nonlinear parabolic equation which has a cell migration term and a population growth term. The mathematical model was used to simulate recent experiments performed to investigate quantitatively the unidirectional formation of a bovine endothelial cell monolayer in vitro. The two parameters included in the equation were estimated using a trial and error method in which the calculated solutions of the various values of the two parameters are compared with the experimental data and the best fit pair is adopted: one parameter, D, which represents the unidirectional cell migration rate and the other, k, which represents the population growth rate. The calculated solutions fit the experimental data well. We also simulated the healing of a mechanically disrupted endothelial monolayer sheet. The significance of cellular biomechanics in tissue formation and design of tissue-engineered devices is discussed.

Characteristic expression of GD1 alpha-ganglioside during lactation in murine mammary gland

Cellular proliferation and differentiation in mammary gland are known to be significantly altered during pregnancy and subsequent lactation. To characterize the different stages of mammary gland during pregnancy and lactation, we analyzed the glycosphingolipid compositions in the mammary gland of DDD and ICR mice at several periods of pregnancy and lactation, and found that the ganglioside composition, but not neutral glycosphingolipids, was characteristically altered during the pregnancy and lactation periods. The concentrations of acidic glycosphingolipids, I3SO3-GalCer 1, GM3, GM1a, GM1b and GD1a, were reduced during the course of pregnancy and lactation. GD1 alpha (III6NeuAc alpha,IV3NeuAc alpha-Gg4Cer) was first detected at the mid-period of pregnancy (12 days of pregnancy for ICR mice), increased in concentration at the late-period of pregnancy (GD1 alpha concentration was 100 times higher at 18 days than that at 12 days of pregnancy), and was a major ganglioside comprising 60-70% of the total lipid-bound sialic acid in the mammary gland of ICR and DDD mice at the lactation period, indicating that expression of GD1 alpha is associated with the lactating mammary gland of mice. In fact, GD1 alpha was highly concentrated in the milk fat globule, in which it was a major component.

Mechanism of chromium(VI) toxicity in Escherichia coli: is hydrogen peroxide essential in Cr(VI) toxicity?

To investigate the role of hydrogen peroxide in Cr(VI) toxicity in vivo toward bacterial cells, we examined the effect of Cr(VI), hydrogen peroxide, sodium azide, and mannitol on the viability of Escherichia coli. Bacterial cells were incubated for 1 h with shaking in the presence of Cr(VI), hydrogen peroxide, sodium azide as catalase inhibitor, and/or mannitol as radical scavenger. The colony-forming ability and double-strand DNA degradation were examined. The viability assays revealed that Cr(VI) toxicity depended on hydroxyl radicals generated in the reaction involving hydrogen peroxide and chromium. Moreover, incubation of E. coli cells with 10 mM Cr(VI) and 3 mM hydrogen peroxide caused the degradation of double-strand DNA in vivo, which was suppressed by the addition of mannitol. These results indicated that hydroxyl radicals generated in the incubation degraded DNA of E. coli cells, resulting in cell death. In the absence of added hydrogen peroxide, the intracellular concentration of hydrogen peroxide in E. coli was low (below 1 microM). A catalase-defective strain incubated in the absence of added hydrogen peroxide remained fully viable after 1 h but showed decreased viability after prolonged incubation (4-8 h). The addition of mannitol suppressed this decrease, suggesting that hydroxyl radicals may be involved in the expression of Cr(VI) toxicity even without added hydrogen peroxide.

Xylanase IV, an Exoxylanase of Aeromonas caviae ME-1 Which Produces Xylotetraose as the Only Low-Molecular-Weight Oligosaccharide from Xylan

A novel xylanase (xylanase IV) which produces xylotetraose as the only low-molecular-weight oligosaccharide from oat spelt xylan was isolated from the culture medium of Aeromonas caviae ME-1. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the xylanase IV molecular weight was 41,000. Xylanase IV catalyzed the hydrolysis of oat spelt xylan, producing exclusively xylotetraose. The acid hydrolysate of the product gave d-xylose. The enzyme did not hydrolyze either p-nitrophenyl-(beta)-d-xyloside, small oligosaccharides (xylobiose and xylotetraose), or polysaccharides, such as starch, cellulose, carboxymethyl cellulose, laminarin, and (beta)-1,3-xylan.

Purification and characterization of D-xylose isomerase from Bifidobacterium adolescentis

D-Xylose isomerase was purified to homogeneity from cell-free extracts of Bifidobacterium adolescentis by ammonium sulfate fractionation and chromatographies on DEAE-cellulose and Butyl-Toyopearl. The molecular weight of the purified enzyme was estimated to be 168,000 by gel filtration on TSKgel G-3000SW, and 53,000 on SDS-polyacrylamide gel electrophoresis. The optimum pH was around 7 and the enzyme was stable at pH 7-8. The enzyme required bivalent cations, Mg2+, Co2+, or Mn2+ for the activity, particularly Mn2+ to be best. The enzyme had a pI of 4.3, and the Km for D-xylose was 4 mM. The N-terminal amino acid sequence of the enzyme was not similar to those of D-xylose isomerases from other sources such as Clostridium thermosulfurogenes, Escherichia coli, or Bacillus subtilis.

Enterotoxin-binding glycoproteins in a proteose-peptone fraction of heated bovine milk

The binding of Escherichia coli heat-labile enterotoxin to caseins, whey proteins, milk fat globule membrane, and proteose-peptone fraction from bovine milk was studied by using the Western blot technique. Two toxin-binding glycoproteins, pp16k and pp20k, with molecular weights of 15,500 and 20,000, respectively, were detected only in a proteose-peptone fraction. These glycoproteins were partially purified by ammonium sulfate precipitation and Toyopearl HW 55 gel filtration chromatography. The binding ability to the toxin was destroyed by periodate treatment or beta-galactosidase treatment, indicating that a carbohydrate moiety, particularly a terminal galactosyl residue, was essential for the binding of the toxin. In contrast, the binding ability was not changed by mild acid treatment, and these glycoproteins did not bind cholera toxin, which can bind to ganglioside GM1, suggesting that the carbohydrate structure of the glycoproteins is different from that of GM1. The N-terminal amino acid sequence and immunoblot analysis indicated that the protein moieties of pp16k and pp20k are identical to alpha-lactalbumin and beta-lactoglobulin, respectively. These toxin-binding glycoproteins were not detected in whey proteins isolated from unheated skim milk, suggesting that they are newly generated during heat treatment of skim milk before the preparation of a proteose-peptone fraction.

Escherichia coli heat-labile enterotoxin binds to glycosylated proteins with lactose by amino carbonyl reaction

The binding of Escherichia coli heat-labile enterotoxin (LT) type I to glycosylated proteins with lactose (Gal beta 1-4Glc) by amino carbonyl reaction was studied by the Western blot assay and by the microtiter well binding assay. LT bound to a lactose-alpha-lactalbumin amino carbonyl product (Lac-LA), whereas cholera toxin did not. The binding ability of Lac-LA was abolished by beta-galactosidase treatment, indicating that the terminal galactose is essential for the binding of LT. The binding of LT to Lac-LA was inhibited by galactose and lactose, and most effectively inhibited by lactulose (Gal beta 1-4Fru), which is a structural analog of the Amadori rearrangement product of the amino carbonyl reaction between lactose and an epsilon-amino group of a lysine residue (lactuloselysine). The results suggest that LT recognizes the portion of lactuloselysine in Lac-LA. LT also bound to a melibiose (Gal alpha 1-6Glc)-alpha-lactalbumin amino carbonyl product (Mel-LA), but the binding ability of Mel-LA was weaker than that of Lac-LA, suggesting that the beta 1-4 linked terminal galactose is dispensable but preferable for the binding. Furthermore, LT bound to the amino carbonyl products of lactose with beta-lactoglobulin, caseins, bovine serum albumin, and ovalbumin. These results indicate that LT binds to the amino carbonyl products between proteins and sugars containing the terminal galactose, such as lactose.

Purification and Characterization of Aeromonas caviae ME-1 Xylanase V, Which Produces Exclusively Xylobiose from Xylan

A xylanase, which produces exclusively xylobiose from oat spelt and birch xylans, was isolated from the culture medium of Aeromonas caviae ME-1. The enzyme (xylanase V) was purified by ammonium sulfate fractionation, hydrophobic interaction, and ion-exchange and gel filtration chromatographies. The homogeneity of the final preparation was demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and agarose gel electrofocusing. The molecular mass and isoelectric point of the xylanase were 46 kDa and 5.4, respectively. Xylanase V had a maximum activity at a pH of 6.8 and at a temperature between 30 and 37°C. It was relatively stable at a pH between 5.0 and 8.6 and a temperature between 25 and 37°C. When soluble birch xylan was used as the substrate, the enzyme had a K m and V max of 2 mg/ml and 182 μmol of xylose equivalent liberated · min -1 · mg of protein -1 , respectively. By the action of xylanase V on xylans (from oat spelt and birch), only one product corresponding to xylobiose was observed by thin-layer chromatography. The xylanase V putative product was confirmed to be xylobiose by acid and enzymatic hydrolyses. The xylanase had neither β-xylosidase, α- l -arabinofuranosidase, cellulase, nor β-1,3-xylanase activities. Xylotriose was the shortest substrate which the enzyme could attack. These findings suggest that xylanase V is a novel enzyme that cleaves a xylobiose unit from one of the ends of xylans, probably by an exomechanism.

NAD(P)H-dependent chromium (VI) reductase of Pseudomonas ambigua G-1: a Cr(V) intermediate is formed during the reduction of Cr(VI) to Cr(III)

An NAD(P)H-dependent Cr(VI) reductase (molecular weight = 65,000) was purified from a Cr(VI)-resistant bacterium, Pseudomonas ambigua G-1. Stoichiometric analysis of the enzymatic reaction showed that the enzyme catalyzed the reduction of 1 mol of Cr(VI) to Cr(III) while consuming 3 mol of NADH as an electron donor. Chromium(VI) was reduced to Cr(V) by one equivalent NADH molecule in the absence of the enzyme. Electron spin resonance analysis showed that Cr(V) species (g = 1.979) was formed during the enzymatic reduction. The amount of Cr(V) species formed was about 10 times larger than that of the nonezymatic reduction. These findings show that the Cr(VI) reductase reduced Cr(VI) to Cr(III) with at least two reaction steps via Cr(V) as an intermediate.

Isometric biaxial tension of smooth muscle in isolated cylindrical segments of rabbit arteries

Biaxial tension developed in the common carotid and femoral arteries of rabbits by the activation of smooth muscle was determined in vitro using cylindrical segments. While the smooth muscle was stimulated with 10(-5) M norepinephrine, the intraluminal pressure and axial force were measured under isometric conditions, i.e., keeping the diameter and length constant. The development of the active tension in the axial direction was roughly proportional to that in the circumferential direction. The ratio of the axial stress response to the circumferential one was positively correlated to the ratio of the axial stretch to the circumferential one. The axial response was larger than expected from the histological observation that the smooth muscle cells align almost circumferentially. This means that although smooth muscle cells are oriented almost circumferentially, the extracellular matrix transmitted the smooth muscle constriction force not only in the circumferential direction, but also in the longitudinal direction under isometric conditions.

Blood rheology in the endotoxin-administered rabbits

The effects of endotoxin on blood rheology were studied in rabbits. Non-treated six rabbits (Group A) were used to obtain control data. Thirteen rabbits who were administered 0.1 mg of endotoxin three times at intervals of 3 days were divided into two groups; seven rabbits (Group B) were injected with 1 ml saline solution as the vehicle for endotoxin at 7 days after the final administration of endotoxin, while the remaining six rabbits (Group C) were administered endotoxin at 0.2 mg/kg on the same day. Blood was sampled from the femoral artery 120 min after the final treatment. Blood viscosity was measured at a shear rate of 150 s-1 at 37 degrees C using a cone-plate viscometer. The passage time for a 5% red blood cell suspension and that for plasma were determined by filtration; the former represents erythrocyte deformability while the latter is related to plasma fluidity. The hematocrit, whole blood viscosity and erythrocyte deformability did not show significant differences among these three groups. The ratio of hematocrit to whole blood viscosity is considered to be an index of oxygen delivery from the hemorheologic point. This index did not show significant difference either. A good correlation was observed between whole blood viscosity and hematocrit in Group A, but not in the endotoxin-treated groups. The plasma fluidity was lower in Groups B and C than in Group A. These data indicate that plasma fluidity and the hematocrit-viscosity relationship are affected in endotoxin-treated rabbits, although blood viscosity, erythrocyte deformability and oxygen delivery hardly changed.

A selective thromboxane synthetase inhibitor, OKY-046, fails to improve blood rheology in endotoxin-shocked rabbits

Effects of a selective thromboxane synthetase inhibitor, (E)-3-[4-(1-imidazolylmethyl)phenyl]-2-propenoic acid hydrochloride monohydrate (OKY-046), were studied hemorheologically in endotoxin shocked-rabbits. The animals were intravenously administrated with 0.1 mg of endotoxin 3 times at intervals of 3 days. At 7 days after the last endotoxin injection, endotoxin (0.2 mg.kg(-1)) was intravenously administrated to induce a shock. OKY-046 (30 mg.kg(-1)) was administrated after hypotension was developed by the endotoxin treatment and, then, it was continuously injected at 0.03 mg.kg(-1).min(-1). Blood pressure remained unchanged and hypotensive was maintained during the treatment with OKY-046. Blood was sampled from the femoral artery 15 (before the administration of OKY-046), 45, and 120 minutes after the final administration of endotoxin. Pa(O)(2) increased, and Pa(CO)(2), arterial pH, and base excess (BE) decreased during the endotoxin shock. The decrease of pH and BE was prevented by the administration of OKY-046. In the endotoxin-shocked animals, hematocrit, whole blood viscosity, erythrocyte deformability, plasma fluidity, and the ratio of hematocrit to whole blood viscosity showed no significant differences between the OKY-046 treated animals and non-treated ones. These data show that a selective thromboxane synthetase inhibitor (OKY-046) does not improve the blood rheology during endotoxin shock, although it seems to prevent the acidosis in some extent.

An evaluation of an in vivo local sound speed estimation technique by the crossed beam method

An in vivo local sound speed estimation technique, using the crossed beam method, has been proposed and its applicability was evaluated. At first, the potential of this technique was studied by a mapping simulation using the ray tracing technique followed by an experiment with a cylindrical agar phantom. The simulation result showed that an exact measurement of local sound speed values was difficult, but the sound speed information for the local region (its relative magnitude to the surrounding medium) was emphasized as a refraction mapping pattern. The experimental results agreed well with the calculation results. Furthermore, a clinical application was performed, using the clinical system (modified electronic linear scanner), on two liver tumor patients.

Structural and compositional difference in the neutral glycolipids between epithelial and non-epithelial tissue of the mouse small intestine

Five major neutral glycolipids, GL-1-GL-5, were isolated from the mouse small intestine. Their structures and distribution were determined by permethylation analysis, sequential degradation with exoglycosidases and/or immunohistochemistry. The molar ratio of GL-1, GL-2, GL-3, GL-4 and Gl-5 in the whole small intestine was 1:0.04:0.03:0.42:0.02. The structures of GL-1 and GL-4 present in epithelial cells were reported previously to be glucosyl ceramide and asialo GM1, respectively (Umesaki, Y., Suzuki, A., Kasama, T., Tohyama, K., Mutai, M. and Yamakawa, T. (1981) J. Biochem. 90, 1731-1738). GL-5, also present in the epithelial cells, was fucosyl asialo GM1, and fucose was shown to be linked to terminal galactose of asialo GM1 in the manner of alpha(1-2) bond. GL-2 and GL-3, present in the residual tissue after scraping the mucosa, were determined to be globoside and Forssman glycolipid, respectively. Both globoside and Forssman glycolipid of the non-epithelial tissue had non-hydroxy fatty acid (C16-C24) in combination with sphingosine (C18) as the ceramide components, in contrast with the ceramide structures of the epithelial glycolipids, which contained alpha-hydroxy fatty acids in combination with phytosphingosine. Immunohistochemical staining using anti-glycolipid antibodies confirmed the distribution of asialo GM1 and fucosyl asialo GM1, and Forssman glycolipid in the epithelial and non-epithelial tissue, respectively.

Change of hematocrit and blood viscosity in cholesterol-fed rabbits

In the cholesterol-fed rabbits, we observed that the whole blood viscosity was maintained at the normal level in spite of the decrease in hematocrit. This phenomenon suggests that there exists some visco-regulatory mechanism, and we could simulate it by a simple integration type model.

Response of femoral arteries to norepinephrine following endotoxicosis

Relation between hypotension caused by endotoxin and the vascular response to norepinephrine was studied in rabbits following bolus injection of endotoxin (2 mg/kg). Seven rabbits were used as the nontreated, control animals (group I). Twelve endotoxin-shocked rabbits were divided into two groups from their hypotensive patterns: gradual hypotension group (group II, five animals) and immediate hypotension group (group III, seven animals). In group II, the mean arterial blood pressure decreased by less than 10% within 5 min after the administration of endotoxin, while the blood pressure immediately dropped over 40% in group III. No significant difference in blood pressure was observed between these two groups at 30, 60, and 240 min after the administration of endotoxin. Femoral arteries were resected from these animals 4 hr after the endotoxin treatment and were used to determine the vascular stiffness and contractile diameter response to 10(-5) M of norepinephrine. The diameter response was not significantly different at each pressure between 0 and 200 mm Hg between groups I and II or between groups I and III. However, the diameter response in the pressure range between 20 and 110 mm Hg was significantly higher in group III than in group II. The maximum diameter response was also significantly higher in group III than in group II. However, there was no significant difference in the wall stiffness between these two groups. These data show that the hypotensive response to endotoxin might be related to the vascular contractile response to norepinephrine.

Uniform strain hypothesis and thin-walled theory in arterial mechanics

The authors (1987), and Chuong and Fung (1986) have shown that the strain and stress distributions in the arterial wall should be more uniform than those calculated on the basis of the conventional assumption that there is no stress over the cross-section of the arterial wall when all external force is removed (zero initial stress hypothesis). Instead of this assumption, the authors have proposed a new hypothesis that the circumferential strain uniformly distributes through the wall thickness at a physiologically normal loading, and named it 'uniform strain hypothesis'. Their results suggest the validity of the thin-walled theory in the vascular mechanics. This paper shows that if the uniform strain hypothesis is applied, the thin-walled theory can be used to accurately determine the constants included in the strain energy density function which describes the mechanical properties of the arterial wall. There were, however, significant differences in the values of the constants between the thin-walled theory and the thick-walled theory if assuming the conventional zero initial stress hypothesis.

Effects of elastase on the stiffness and elastic properties of arterial walls in cholesterol-fed rabbits

The effect of cholesterol feeding and elastase administration on the arterial stiffness and elastic properties was investigated in rabbits by pressure-diameter tests on excised thoracic aortas, common carotid and femoral arteries. Rabbits in groups RA and RB were fed 1% cholesterol diet for 14 weeks. Groups RC and RD were fed the cholesterol diet for the first 7 weeks, and then given regular chow for the last 7 weeks. In addition, rabbits in groups RB and RC were administered elastase daily for the last 7 weeks. Rabbits in group RE were fed the regular chow for 14 weeks and served as the control group. The arterial stiffness and the elastic modulus of wall material in the RA rabbits were generally higher than those in the control rabbits. Administration of elastase and/or feeding of the regression diet decreased the wall stiffness and elastic modulus significantly, although the effect of elastase did not appear clearly when used in combination with the regression diet. The cholesterol feeding decreased the ratio of thickness to wall radius, whereas the ratio was more or less increased by the elastase administration and/or the regression diet.