Carbohydrate utilization by the gut microbiome determines host health responsiveness to whole grain type and processing methods

Little is known about how interactions among grain processing, grain type, and carbohydrate utilization (CU) by the microbiome influence the health benefits of whole grains. Therefore, two whole grains - brown rice and whole wheat - and two processing methods - boiling (porridge) and extrusion - were studied for their effects on host metabolic outcomes in mice harboring human microbiomes previously shown in vitro to have high or low CU. Mice carrying either microbiome experienced increases in body weight and glycemia when consuming Western diets supplemented with extruded grains versus porridge. However, mice with the high but not low CU microbiome also gained more weight and fat over time and were less glucose tolerant when consuming extruded grain diets. In high CU microbiome mice, the exacerbated negative health outcomes associated with extrusion were related to altered abundances of Lachnospiraceae and Ruminococcaceae as well as elevated sugar degradation and colonic acetate production. The amplicon sequence variants (ASVs) associated with extruded and porridge diets in this in vivo study were not the same as those identified in our prior in vitro study; however, the predicted functions were highly correlated. In conclusion, mice harboring both high and low CU microbiomes responded to the whole grain diets similarly, except the high CU microbiome mice exhibited exacerbated effects due to excessive acetate production, indicating that CU by the microbiome is linked to host metabolic health outcomes. Our work demonstrates that a greater understanding of food processing effects on the microbiome is necessary for developing foods that promote rather than diminish host health.Abbreviations: CU- carbohydrate utilization; SCFA- short-chain fatty acids; GF- germ-free; HMA, human-microbiome associated; ipGTT- intraperitoneal glucose tolerance test; HOMA-IR- Homeostatic Model Assessment for Insulin Resistance; AUC- area under the glycemia curve; ASV- amplicon sequence variant; lf- low-fat; wd- Western diet; wd_wwp- Western diet containing whole wheat porridge; wd_wwe- Western diet containing whole wheat extrudate; wd_bre- Western diet containing brown rice extrudate; wd_extr- Western diet containing either whole wheat or brown rice extrudate.

The Gut Microbiota Regulates the Metabolic Benefits Mediated by Red Raspberry Polyphenols

Objectives

Red raspberry (RR) polyphenols, including ellagic acid and their gut-derived metabolites, the urolithins, reduce inflammation and improve insulin sensitivity. However, it is unknown whether the gut microbiota is responsible for these health benefits and why certain individuals do not transform ellagic acid into urolithins. Here, we determined the causative role for the microbiome in mediating the health benefits from RR polyphenols using germ-free and conventionalized mouse models of diet-induced obesity. We also tested whether Gordonibacter urolithinfaciens (G. uro), a gut microbe previously shown to metabolize ellagic acid into urolithins, could enhance metabolic benefits when administered as a synbiotic with RR polyphenols.

Methods

RR polyphenols were extracted using a macroporous ion-exchange resin column to remove sugars and fibers. C3H/HeN mice with (CVZ) or without a microbiota (GF) were fed either a low fat (LF), high fat (HF), or HF diet with RR polyphenols (HF + RR) for 12 weeks. For synbiotic studies, GF C57BL/6 mice were given a G. uro deficient-microbiome and then fed either a HF or HF + RR diet plus 20% fructose water with or without G. uro for 7 weeks.

Results

Feeding a HF diet increased body weight and fat mass for both GF and CVZ mice compared to feeding a LF diet (P < 0.05). Feeding a HF diet with RR polyphenols significantly decreased visceral adipose tissue and liver triglycerides (P < 0.05) compared to a HF control diet in CVZ but not GF mice. G. uro administration to mice receiving a HF diet and fructose water significantly reduced body weight, body fat percentage, fasting blood glucose, and subcutaneous adipose tissue mass as well as increased ileal tight junction protein gene expression (P < 0.05) compared to controls. Notably, mice supplemented with both G. uro and RR polyphenols experienced no metabolic improvements compared to controls (P < 0.05).

Conclusions

Our results demonstrate that the microbiome is required for mediating RR polyphenol metabolic benefits. Supplementation of G. uro improved metabolic health; however, those beneficial effects were abrogated in the presence of RR polyphenols. Together, these results highlight the importance of considering specific diet-microbiota interactions when developing foods for preventing and treating obesity-related diseases.

Funding Sources

USDA NIFA.

Preclinical monotherapeutic and anti-PD-1 synergistic anti-tumor efficacy of MNC-168, a novel human-derived live biotherapeutic product

e14581

Background: Human gut microbiome has been extensively demonstrated as a critical causative factor in determining the efficacy of cancer immunotherapy. Cumulative clinical evidences indicate the prevalent presence of Enterococcus species in the responder of anti-PD-1 treated patients. We here demonstrated the preclinical anti-tumor efficacy of a novel human derived Enterococcus strain MNC-168. Methods: Using multiple murine syngeneic cold tumor models and in vivo pharmacokinetics mouse model, we characterized the anti-tumor activity and pharmacokinetics of MNC-168 via oral-delivered route in monotherapy and immune checkpoint inhibitor (ICI) anti-mPD-1 combination. Systematic multi-omics analyses and in vitro mechanistic study were conducted to reveal the biomarkers and mode of action of MNC-168. Results: We found MNC-168 significantly and mono-therapeutically counteract tumor development in diverse tumor models, including colorectal cancer (with tumor inhibition ratio of 65.5%), hepatocellular carcinoma (27.4%), fibrosarcoma (33.5%) and renal carcinoma (56.4%). Notably, MNC-168 in combination with anti-mPD-1 synergistically exerted the tumor inhibition ratio up to 68.3-89.2% and significantly reverse anti-mPD-1 non-responsiveness. Integrated multi-omics analyses and in vitro validation study revealed the mechanism by which MNC-168 reinvigorates the immune system through targeting multiple routes, including activating systemic and tumor-resident innate and adaptive immunity, removal of tumor physical barrier, reinforced recruitment of tumor-infiltrating lymphocytes, and maintenance of immuno-stimulant activity via production of immune-simulating metabolites. Activation and boosting of interferon-γ production of CD8 T cells and CD4 T cells are the vital mediators for the anti-tumor ability of MNC-168. In vivo pharmacokinetics study shows that the anti-tumor efficacy of MNC-168 is positively correlated with gut-restricted abundance of MNC-168. Conclusions: MNC-168 is highly potently used as a first-in-class live biotherapeutic product for cancer monotherapy and promoting efficacy of ICI-mediated cancer immunotherapy.

Prebiotic-Induced Anti-tumor Immunity Attenuates Tumor Growth

Growing evidence supports the importance of gut microbiota in the control of tumor growth and response to therapy. Here, we select prebiotics that can enrich bacterial taxa that promote anti-tumor immunity. Addition of the prebiotics inulin or mucin to the diet of C57BL/6 mice induces anti-tumor immune responses and inhibition of BRAF mutant melanoma growth in a subcutaneously implanted syngeneic mouse model. Mucin fails to inhibit tumor growth in germ-free mice, indicating that the gut microbiota is required for the activation of the anti-tumor immune response. Inulin and mucin drive distinct changes in the microbiota, as inulin, but not mucin, limits tumor growth in syngeneic mouse models of colon cancer and NRAS mutant melanoma and enhances the efficacy of a MEK inhibitor against melanoma while delaying the emergence of drug resistance. We highlight the importance of gut microbiota in anti-tumor immunity and the potential therapeutic role for prebiotics in this process.

Stearidonic-Enriched Soybean Oil Modulates Obesity, Glucose Metabolism, and Fatty Acid Profiles Independently of Akkermansia muciniphila

SCOPE

Previous studies have suggested that diets rich in omega-3 and low in omega-6 long-chain polyunsaturated fatty acids (PUFAs) can limit the development of metabolic syndrome (MetS). Transgenic soybeans yielding oils enriched for omega-3 PUFAs represent a new and readily-available option for incorporating omega-3 PUFAs into diets to provide health benefits.

METHODS AND RESULTS

Transgenic soybean oils, enriched for either stearidonic acid (SDA) or eicosapentaenoic acid (EPA), are incorporated into diets to test their effects on limiting the development of MetS in a mouse model of diet-induced obesity. Supplementation with SDA- but not EPA-enriched oils improved features of MetS compared to feeding a control wild-type oil. Because previous studies have linked the gut microorganism Akkermansia muciniphila to the metabolic effects of feeding omega-3 PUFAs, the causal contribution of A. muciniphila to mediating the metabolic benefits provided by SDA-enriched diets is investigated. Although A. muciniphila is not required for SDA-induced metabolic improvements, this microorganism does modulate levels of saturated and mono-unsaturated fatty acids in host adipose tissues.

CONCLUSION

Together, these findings support the utilization of SDA-enriched diets to modulate weight gain, glucose metabolism, and fatty acid profiles of liver and adipose tissue.

Red Raspberry Polyphenols Attenuate High-Fat Diet-Driven Activation of NLRP3 Inflammasome and its Paracrine Suppression of Adipogenesis via Histone Modifications

SCOPE

The authors aim to investigate the mechanisms by which red raspberry (RR) polyphenolic fractions regulate obesity and inflammation with an emphasis on the crosstalk between adipose tissue macrophages (ATM) and adipocyte progenitors.

METHODS AND RESULTS

C57BL/6 male mice are fed either a high-fat (HF) diet or an HF diet supplemented with a RR polyphenolic fraction from whole fruit, pulp, or seed. Supplementation with pulp significantly increases energy expenditure and reduces HF-diet-induced obesity and insulin resistance. The pulp, and to a lesser extent, whole polyphenols, decreases the recruitment of ATM, activation of the nod-like receptor protein 3 (NLRP3) inflammasome, and adipocyte hypertrophy, which is associated with epigenetic modulation of adipogenesis (e.g., H3K27Ac, H3K9Ac). Results from an IL-1β reporter assay in J774 macrophages recapitulate the inhibitory role of RR polyphenols on NLRP3 inflammasome activation. Using conditioned media from macrophages, it is demonstrated that RR polyphenols reverse the IL-1β-mediated epigenetic suppression of H3K27Ac in adipocyte progenitor cells.

CONCLUSIONS

RR polyphenols from pulp and whole fruit serve as an inhibitor for NLRP3 inflammasome activation and an epigenetic modifier to regulate adipogenesis, which confers resistance against diet-induced obesity and metabolic dysfunction.

Urolithin A, a Gut Metabolite, Improves Insulin Sensitivity Through Augmentation of Mitochondrial Function and Biogenesis

OBJECTIVE

Urolithin A (UroA) is a major metabolite of ellagic acid produced following microbial catabolism in the gut. Emerging evidence has suggested that UroA modulates energy metabolism in various cells. However, UroA's physiological functions related to obesity and insulin resistance remain unclear.

METHODS

Male mice were intraperitoneally administrated either UroA or dimethyl sulfoxide (vehicle) along with a high-fat diet for 12 weeks. Insulin sensitivity was evaluated via glucose and insulin tolerance tests and acute insulin signaling. The effects of UroA on hepatic triglyceride accumulation, adipocyte size, mitochondrial DNA content, and proinflammatory gene expressions were determined. The impact of UroA on macrophage polarization and mitochondrial respiration were assessed in bone marrow-derived macrophages.

RESULTS

Administration of UroA (1) improved systemic insulin sensitivity, (2) attenuated triglyceride accumulation and elevated mitochondrial biogenesis in the liver, (3) reduced adipocyte hypertrophy and macrophage infiltration into the adipose tissue, and (4) altered M1/M2 polarization in peritoneal macrophages. In addition, UroA favored macrophage M2 polarization and mitochondrial respiration in bone marrow-derived macrophages.

CONCLUSIONS

UroA plays a direct role in improving systemic insulin sensitivity independent of its parental compounds. This work supports UroA's role in the metabolic benefits of ellagic acid-rich foods and highlights the significance of its microbial transformation in the gut.

Topological magnon insulator with a Kekulé bond modulation

We examine the combined effects of a Kekulé coupling texture (KC) and a Dzyaloshinskii-Moriya interaction (DMI) in a two-dimensional ferromagnetic honeycomb lattice. By analyzing the gap closing conditions and the inversions of the bulk bands, we identify the parameter range in which the system behaves as a trivial or a nontrivial topological magnon insulator. We find four topological phases in terms of the KC parameter and the DMI strength. We present the bulk-edge correspondence for the magnons in a honeycomb lattice with an armchair or a zigzag boundary. Furthermore, we find Tamm-like edge states due to the intrinsic on-site interactions along the boundary sites. Our results may have significant implications to magnon transport properties in the 2D magnets at low temperatures.

Act1 is a negative regulator in T and B cells via direct inhibition of STAT3

Although Act1 (adaptor for IL-17 receptors) is necessary for IL-17-mediated inflammatory responses, Act1- (but not Il17ra-, Il17rc-, or Il17rb-) deficient mice develop spontaneous SLE- and Sjögren's-like diseases. Here, we show that Act1 functions as a negative regulator in T and B cells via direct inhibition of STAT3. Mass spectrometry analysis detected an Act1-STAT3 complex, deficiency of Act1 (but not Il17ra-, Il17rc-, or Il17rb) results in hyper IL-23- and IL-21-induced STAT3 activation in T and B cells, respectively. IL-23R deletion or blockade of IL-21 ameliorates SLE- and Sjögren's-like diseases in Act1-/- mice. Act1 deficiency results in hyperactivated follicular Th17 cells with elevated IL-21 expression, which promotes T-B cell interaction for B cell expansion and antibody production. Moreover, anti-IL-21 ameliorates the SLE- and Sjögren's-like diseases in Act1-deficient mice. Thus, IL-21 blocking antibody might be an effective therapy for treating SLE- and Sjögren's-like syndrome in patients containing Act1 mutation.

Role of Autophagy in Ovarian Cryopreservation by Vitrification

BACKGROUND

Ovarian cryopreservation by vitrification and transplantation are useful methods to recover female fertility after radiotherapy and chemotherapy. As type II programmed cell death, autophagy plays important roles in ovarian follicle development, ovarian follicle atresia and anti-stress injury.

OBJECTIVE

The potential role of autophagy in ovarian vitrification was investigated.

MATERIALS AND METHODS

Mouse ovaries were cryopreserved by vitrification, and autophagy was treated, after which the ovarian histology was checked, and ovarian follicles were counted. The apoptotic rate was detected by TUNEL, and apoptotic molecular marker cleaved caspase-3 was checked by immunofluorescence and western blot analysis.

RESULTS

Our results suggested that autophagy was increased in the process of vitrification compared with the fresh ovaries (p<0.05). The number of primordial follicles was decreased through inhibiting or over-activating the autophagy by autophagy inhibitor or activator (p<0.05). However, the number of primary follicles, antral follicles and atretic follicles was not significantly different compared with vitrified/warmed groups. The apoptotic rate was significantly increased in the vitrified/warmed, autophagy-inhibiting and over-activating groups compared with the fresh group (p<0.05), and this result was further confirmed by western blot analysis.

CONCLUSIONS

Taken together, autophagy was activated in the ovarian cryopreservation by vitrification and plays a role in a natural adaptive response to cold stress in ovarian cryopreservation by vitrification.

[Prognosis of the central nervous system involvement in patients with hemophagocytic lymphohistiocytosis]

Objective: To investigate the characteristics and prognostic factor of central nervous system (CNS) involvement in patients with hemophagocytic lymphohistiocytosis (HLH) . Methods: From January 2006 to October 2015, 152 patients with HLH, 88 patients had CNS involvement, their clinical data were collected, and survival was analyzed using the Kaplan-Meier life table method, univariate and multivariate Cox regression model analyses were applied to identify the risk factors of prognosis. Results: ①57.9% patients complicated with neurological symptoms, cerebrospinal fluid abnormalities were observed in 37.0% patients, 57.5% patients had abnormal neuroradiology. ②36 patients survived well, 3 patients lost to follow-up, 49 dead, 1 survival patient had epilepsy. ③The 3-year overall survival rate of 88 patients was 44%. ④abnormal CSF and unreceived IT bore a significant, independent adverse prognostic value (P<0.05) . Conclusion: CNS involvement in HLH has a high frequency and poor prognosis, few patients remained neurologic sequelae; abnormal CSF related to poor prognosis, positive intrathecal injections could improve the prognosis.

Analytical study of the edge states in the bosonic Haldane model

We investigate the properties of magnon edge states in a ferromagnetic honeycomb spin lattice with a Dzialozinskii-Moriya interaction (DMI). We derive analytical expressions for the energy spectra and wavefunctions of the edge states localized on the boundaries. By introducing an external on-site potential at the outermost sites, we show that the bosonic band structure is similar to that of the fermionic graphene. We investigate the region in the momentum space where the bosonic edge states are well defined and we analyze the width of the edge state and their dependence with the DMI strength. Our findings extend the predictions using topological arguments and they allow size-dependent confirmation from possible experiments.

[X-linked lymphoproliferative syndrome type 1 complicated with secondary hemophagocytic lymphohistiocytosis and ileal perforation: case report and literature review]

OBJECTIVE

To analyze and summarize the clinical characteristics, laboratory tests and treatment of X-linked lymphoproliferative syndrome type 1 (XLP-1).

METHOD

A retrospective study was done in 2012 on an XLP-1 patient to collect the data on clinical manifestation, laboratory examination, gene and protein expression, complications and prognosis. Literatures were reviewed in Pubmed with the key word"X-linked lymphoproliferative syndrome".

RESULT

The patient with persistent high fever, jaundice, abdominal distension, hepatosplenomegaly and lymphadenectasis, rash and suspicious positive family history; the patient eventually died of hemophagocytic lymphohistiocytosis (HLH), with intestinal perforation, intestinal infection and bleeding after being infected with EB virus. This patient with SH2D1A gene exon 1 large fragment of the coding region of the nucleotide deletion and insertion mutations causing missense mutations (p.Leu25Lys) and nonsense mutations (stop codon TAG was inserted after missense mutation so that the protein encoded by the early termination of the 25 amino acids), which led to SAP protein missing. The expression of SAP in his mother was also partly missing. Retrieval of reports on XLP-1 was conducted through literature search (included totally 157 cases) at home and abroad, positive family history accounted for 60.6%(40/66); lymphoma incidence accounted for 49.7%(72/145); low gamma globulin occurred in 24.8%(39/157) of cases; secondary HLH ratio accounted for 43.3%(68/157); XLP-1 in patients with hemorrhagic enteritis and gastritis was low, accounted for only 2.6%(3/116).

CONCLUSION

XLP-1 patients occasionally develop necrotic enteritis complicated with ileal perforation.XLP-1 with large fragment deletion of SH2D1A gene might be associated with serious gastrointestinal manifestations.

Neutral sphingomyelinase 2 is a key factor for PorB-dependent invasion of Neisseria gonorrhoeae

Disseminated gonococcal infection (DGI) is a rare but serious complication caused by the spread of Neisseria gonorrhoeae in the human host. Gonococci associated with DGI mainly express the outer membrane protein PorBIA that binds to the scavenger receptor expressed on endothelial cells (SREC-I) and mediates bacterial uptake. We recently demonstrated that this interaction relies on intact membrane rafts that acquire SREC-I upon attachment of gonococci and initiates the signalling cascade that finally leads to the uptake of gonococci in epithelial cells. In this study, we analysed the role of sphingomyelinases and their breakdown product ceramide. Gonococcal infection induced increased levels of ceramide that was enriched at bacterial attachment sites. Interestingly, neutral but not acid sphingomyelinase was mandatory for PorBIA -mediated invasion into host cells. Neutral sphingomyelinase was required to recruit the PI3 kinase to caveolin and thereby activates the PI3 kinase-dependent downstream signalling leading to bacterial uptake. Thus, this study elucidates the initial signalling processes of bacterial invasion during DGI and demonstrates a novel role for neutral sphingomyelinase in the course of bacterial infections.

Transcriptional landscape and essential genes of Neisseria gonorrhoeae

The WHO has recently classified Neisseria gonorrhoeae as a super-bacterium due to the rapid spread of antibiotic resistant derivatives and an overall dramatic increase in infection incidences. Genome sequencing has identified potential genes, however, little is known about the transcriptional organization and the presence of non-coding RNAs in gonococci. We performed RNA sequencing to define the transcriptome and the transcriptional start sites of all gonococcal genes and operons. Numerous new transcripts including 253 potentially non-coding RNAs transcribed from intergenic regions or antisense to coding genes were identified. Strikingly, strong antisense transcription was detected for the phase-variable opa genes coding for a family of adhesins and invasins in pathogenic Neisseria, that may have regulatory functions. Based on the defined transcriptional start sites, promoter motifs were identified. We further generated and sequenced a high density Tn5 transposon library to predict a core of 827 gonococcal essential genes, 133 of which have no known function. Our combined RNA-Seq and Tn-Seq approach establishes a detailed map of gonococcal genes and defines the first core set of essential gonococcal genes.

Coupled-cluster calculations for the ground and excited states of the spin-half XXZ model

The coupled-cluster method is applied to the spin-1/2 antiferromagnetic XXZ model on a square lattice by employing an approximation which contains two-body long-range correlations and high-order four-body local correlations. Improvement is found for the ground-state energy, the sublattice magnetization and the critical anisotropy when comparing with the approximation including the two-body correlations alone. We also obtain the full excitation spectrum which is in good agreement with the quantum Monte Carlo results and the high-order spin-wave theory.

Longitudinal excitations in quantum antiferromagnets

By extending our recently proposed magnon-density waves to low dimensions, we investigate, using a microscopic many-body approach, the longitudinal excitations of the quasi-one-dimensional (quasi-1d) and quasi-2d Heisenberg antiferromagnetic systems on a bipartite lattice with a general spin quantum number. We obtain the full energy spectrum of the longitudinal mode as a function of the coupling constants in the original lattice Hamiltonian and find that it always has a nonzero energy gap if the ground state has a long-range order and becomes gapless for the pure isotropic 1d model. The numerical value of the minimum gap in our approximation agrees with that of a longitudinal mode observed in the quasi-1d antiferromagnetic compound KCuF3 at low temperature. It will be interesting to compare values of the energy spectrum at other momenta if their experimental results are available.

[Characterization of toxin-antitoxin systems in Mycobacterium tuberculosis]

OBJECTIVE

To characterize the toxin-antitoxin system (TA system) in Mycobacterium tuberculosis, which consist of MazF homologue gene and its upstream gene.

METHODS

Seven M. tuberculosis MazF homologues were induced alone or co-expressed with their upstream genes respectively in Escherichia coli and Mycobacterium smegmatis, to test the toxic effects of the MazF homologues on bacteria growth, and the antitoxic effects of protein encoded by their upstream genes. The RNA cleavage activity of MazF homologous was identified in vitro with Rv0707 mRNA as the substrate. The promoter region of the identified toxin-antitoxin loci in M. tuberculosis was cloned in front of the lacZ reporter gene in pSD5B vector. The promoter activity was measured under the normal or starvation condition.

RESULTS

The growth of either E. coli or M. smegmatis was inhibited by four MazF homologous proteins, among which Rv1102c, Rv1991c and Rv2801c, but not mtPemK, had the RNA cleavage activities. The toxic effects and RNA cleavage activities of Rv1102c, Rv1991c and Rv2801c were inhibited by their corresponding antitoxin Rv1103c, Rv1991a and Rv2801a, respectively. The other three MazF homologues, Rv1942c, Rv0659c and Rv1495, were not toxic to E. coli and M. smegmatis and also could not cleave RNA. It was found that the promoter activities of Rv2801a-2801c and Rv1991a-1991c systems were significantly increased under the complete starvation condition.

CONCLUSION

Our results demonstrated that Rv1103c-1102c, Rv1991a-1991c, Rv2801a-2801c and mtPemI-mtPemK were typical toxin-antitoxin systems in M. tuberculosis. Rv1102c, Rv1991c and Rv2801c were toxin proteins which inhibited cell growth through their RNA cleavage activities, while the mechanism of mtPemK toxin is still unknown. It is possible that Rv2801a-2801c and Rv1991a-1991c systems are involved in the starvation stress response.

Preparation of microporous aluminium anodic oxide film modified Pt nano array electrode and application in direct measurement of nitric oxide release from myocardial cells

A novel method for fabricating a nano array electrode (NAE) by using micropores of aluminium anodic film as templates was investigated. To evaluate the NAE, cyclic scanning of NAE in Fe(CN)6(3-) solution was performed and a sigmoidal shaped voltammogram was obtained. The NAE was designed to measure nitric oxide (NO) in vitro and in vivo. Studies showed that it was a sensitive and selective NO electrochemical sensor. NO release from myocardial cells was directly measured with this NAE and the results were satisfactory.

Determination of sulfur dioxide in vitriol plant wastewater by using a polyNiMe4TAA electrochemically modified Pt microelectrode

A Pt microelectrode modified with nickel(II) polytetramethyldibenzo[b,i]tetraaza[14]annulene was prepared by electropolymerization of nickel(II) tetramethyldibenzo[b,i]tetraaza[14]annulene monomers and applied to determine sulfur dioxide in vitriol plant wastewater. For determination of SO2 with this electrochemically modified Pt microelectrode, the linear range was from 9.6 x 10(-6) to 2.4 x 10(-4) mol L-1, the sensitivity was 1.8 x 10(-4) A L mol-1, the detection limit was calculated to be 4.8 x 10(-6) mol L-1 (S/N = 3), the response time was less than 20 s and the relative standard deviation was found to be 2.1% on analyzing 4.8 x 10(-5) mol L-1 SO2 solution repeatedly (n = 7). These results demonstrated good accuracy compared with those obtained by the conventional iodimetric method.

Amperometric ultramicrosensors for peroxynitrite detection and its application toward single myocardial cells

The research studied the concentration variation of peroxynitrite anion (O=N-O-O-) released from cultured neonatal myocardial cells induced by ischemia/reperfusion and studied the protective effect of melatonin on the injury. For this purpose, amperometry peroxynitrite ultramicrosensors (UMS) were fabricated and constructed by electropolymerizing inorganic macromolecular film of tetraaminophthalocyanine manganese(II) and coating chemically with poly(4-vinylpyridine). Under optimum conditions, the UMS showed high selectivity and sensitivity to peroxynitrite determination with a calculated detection limit of 1.8 x 10(-8) mol/L (S/N of 3). The detection of peroxynitrite was based on electrocatalytic reduction of peroxynitrite. The mechanism of catalysis was also discussed. The UMS should be promising for in vivo measurement of peroxynitrite without interference or fouling. Peroxynitrite released from myocardial cells both in the ischemic period and in the reperfusion period was measured directly. This approach may lead to important information for myocardial cells on the mechanism of injury and prospective treatments of medicine such as melatonin.

Measurement of nitric oxide released in the rat heart with an amperometric microsensor

Nitric oxide (NO) plays an important role in various physiological processes, acting either as an intra- and intercellular messenger or as a toxic agent. The detection and quantification of NO have been accomplished by a variety of methodologies. In the present study, real-time production of NO in the rat heart was continuously measured by using a novel copper-platinum microparticle-modified NO electrochemical microsensor. The linearity range of the microsensor is between 8.0 x 10(-8) and 4.8 x 10(-6) mol L-1 and the detection limit is 3.0 x 10(-8) mol L-1. NO release from the rat heart stimulated by the agonists L-arginine and acetylcholine was observed, and the responses were decreased by the NO synthase inhibitor L-N omega-nitroarginine. In addition, the effect of sodium nitroprusside (SNP), a NO donor, was also studied. SNP increases the concentration of NO in the rat heart. The experiments showed that electrochemical detection is suitable for detecting and quantifying NO in biological systems.

[Theoretical analysis of Cu-O bond stretching vibration out of CuO2 plane of bi-system high temperature]

In this article, according to the molecule vibration theory and on the base of simple model, the stretching vibration modes of Cu-O bond out of CuO2 plane were analysed and stretching vibration frequencies were calculated. The calculating result approximately coincided with the result of experimental analysis.

[Analysis of Cu-O bond stretching vibration in CuO2 plane of Bi-system high temperature superconductor]

Infrared absorption spectra of Bi-system high zero resistance temperature (Tc) superconductors were measured. The relation between Cu-O bond stretching vibration in CuO2 plane and superconducting properties of Bi-system high Tc superconductors were analysed and discussed. The result of analysis indicated that the change of absorption peak strength of Cu-O bond stretching vibration was similar to the change of Tc. The reason was related to the coupling between the phonon and free carrier. And according to the theory of molecule vibration, the frequencies of Cu-O bond stretching vibration in CuO2 plane were calculated on the base of simplified model.

[Synthesis of new pyrazoline fluorescent compounds and their IR spectra and fluorescence property]

The Fluorescent compounds of pyrazoline have been used in many field. According to Schellhammer theory, we designed and synthesized five new benzothiazoyl pyrazoline compounds. Their infrared spectra and fluorescent spectra of five compounds were detected. The results showed that five compounds have fluorescence, fluorescence emission wavelength is about 450nm. Effect of different substituents on the fluorescent intensity was investigated.

[Effects of flunarizine and vitamin C on hemodynamics in rat heart subjected to ischemia-reperfusion]

Langendorff perfusion isolated rat heart was subjected to total global ischemia (coronary flow rate is equal to zero) for 10 minutes and reperfusion for 15 minutes. The heart rate (HR), left ventricular developed pressure (LVDP), coronary flow rate (CFR), electrocardiogram (ECG) and the effects of calcium antagonist-flunarizine (FNZ) and/or oxygen free radical scavenger--vitamine C on the above parameters were observed. The results showed that FNZ dilated coronary vessel (P < 0.01) and had a slight negative chronotropic effect, but it had no effect on LVP. Vitamine C did not affect HR, LVP and CFR. The recovery of the product of HR and LVDP-Rate Pressure Product (RPP) in the FNZ + Vit. C group, Vit. C group and FNZ group was significantly higher than that in the control group (P < 0.05) at ten minutes reperfusion. All the results suggest that FNZ and Vit. C may improve the recovery of heart function after reperfusion.

[Protective effects of flunarizine and vitamin C on isolated rat heart subjected to ischemia-reperfusion injury]

Isolated rat heart was subjected to Langendorff perfusion for 10 minutes of total global ischemia, and reperfusion for 15 minutes. The content of myocardial intracellular calcium, content of oxygen free radical induced lipid peroxide mitabolite-malondialdehyde (MDA), content of Lactic dehydrogenase (LDH) in coronary effluent, and the change of myocardial morphology were studied. The effects of flunarizine(FNZ) and/or vitamin C(Vit C) on the above parameters were observed. The results showed that, at 15 minutes of reperfusion, the contents of myocardial intracellular calcium, of MDA in myocaredium and of LDH in coronary effluent in the FNZ + Vit C group, Vit C group and FNZ group were all lower than those in the control group, and the change of morphology in the three groups was also slighter than that in the control group. When FNZ and Vit C were administered together, the effect was more marked and equivalent to the sum total of the effects of the two drugs. These suggest that both FNZ and Vit C reduce reperfusion injury through suppression of myocardium calcium overload and oxygen free radical damage.

Lack of pharmacokinetic interaction between dipyridamole and zalcitabine in rats

Resistance usually manifests following long-term dideoxynucleoside therapy of HIV-1 infection. This period appears to coincide with reduced dosage regimens. Resistance that is associated with long-term monotherapy may, in part, be due to decreased intracellular drug concentrations. It has been reported that intracellular uptake of the dideoxynucleosides is enhanced by dipyridamole. Hence, dipyridamole may potentially be used to optimize the effects of zalcitabine in HIV-1 antiretroviral "cocktail". The purpose of this study was to characterize the pharmacokinetics of zalcitabine when administered alone and concomitantly with dipyridamole. Also, we determined, indirectly, whether dipyridamole modulated the intracellular uptake of zalcitabine. Rats were intravenously administered either zalcitabine 100 mg/kg alone or with dipyridamole 15 mg/kg. Except renal clearance (CIR), there were no statistically significant differences in the pharmacokinetic parameters including the steady-state volume of distribution and distribution coefficient. Zalcitabine plasma concentrations declined rapidly in a bi-exponential fashion, with a terminal half-life of 1.03 +/- 0.18 hr. alone versus 1.08 +/- 0.22 hr. with dipyridamole. The area under the concentration-time curve was not significantly different with or without dipyridamole. ClR, was 1.42 +/- 0.37 l/hr./kg for zalcitabine alone versus 1.09 +/- 0.28 l/hr./kg with dipyridamole. Our single dose study show that zalcitabine disposition kinetics were not significantly modulated by dipyridamole.

Three-dimensional structure of the porcine gastric H,K-ATPase from negatively stained crystals

A low-resolution three-dimensional model of membrane-bound H,K-ATPase from pig gastric mucosa has been reconstructed by electron microscopy and image processing of two-dimensional crystals in negative stain. The crystal formation is induced by magnesium and vanadate, which stabilize the E2 conformation of the enzyme. The unit cell, with a size of a = b = 123 A, gamma = 90 degrees, has tetragonal p4 symmetry. There are four separate alpha beta protomers within each unit cell. The high-contrast region is limited to the cytoplasmic part of the protein. The total volume of the observed asymmetric protein domain corresponds to a molecular mass of 80-90 kDa. It consists mainly of a large pear-shaped domain measuring 60 x 45 A2, with a height of 50 A as measured perpendicular to the membrane plane. A small stalk segment, 20 A in length, forms a connection to the transmembrane region.

Two-dimensional crystals of membrane-bound gastric H,K-ATPase

Two-dimensional crystallization of membrane-bound H,K-ATPase (EC 3.6.1.36) in vesicle preparations from parietal cells of hog gastric mucosa was induced by an imidazole buffer containing Mg2+ and VO3- ions. A continuous reorganization of the protein molecules started within a few hours by the formation of linear arrays. At later stages confluent two-dimensional crystals were formed. Electron microscopy and image processing showed that these were of a single tetragonal type. The asymmetric unit consisted of one pear-shaped protein domain corresponding to a H,K-ATPase protomer. Through stain-deficient contact regions four adjacent protein units were connected forming a tetrameric structure.