Protective Mechanisms of Juncus effusus and Carbonized Juncus effusus against D-Galactosamine-Induced Acute Liver Injury in Mice

This study investigated the hepatoprotective effects of Juncus effusus (J. effusus) and Carbonized J. effusus against liver injury caused by D-galactosamine (D-GalN) in mice. J. effusus and Carbonized J. effusus were administered by gavage once daily starting seven days before the D-GalN treatment. The results of the study indicated that J. effusus and Carbonized J. effusus suppressed the D-GalN-induced generation of serum alanine transaminase (ALT), aspartate aminotransferase (AST), hepatic malondialdehyde (MDA) and tumor necrosis factor-alpha (TNF-α) was observed. The values of superoxide dismutase (SOD) exhibited an increase. In addition, J. effusus and Carbonized J. effusus promoted the protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2), NADPH quinone oxidoreductase-1 (NQO-1), heme oxygenase-1 (HO-1) as well as the mRNA expression of Nrf2, HO-1, NQO-1 and Glutamate cysteine ligase catalytic subunit (GCLC). The compressed Carbonized J. effusus demonstrated the optimum impact. These results suggest that J. effusus and Carbonized J. effusus protect against D-GalN-induced acute liver injury through the activation of the Nrf2 pathway.

RNF115/BCA2 deficiency alleviated acute liver injury in mice by promoting autophagy and inhibiting inflammatory response

The E3 ubiquitin ligase RING finger protein 115 (RNF115), also known as breast cancer-associated gene 2 (BCA2), has been linked with the growth of some cancers and immune regulation, which is negatively correlated with prognosis. Here, it is demonstrated that the RNF115 deletion can protect mice from acute liver injury (ALI) induced by the treatment of lipopolysaccharide (LPS)/D-galactosamine (D-GalN), as evidenced by decreased levels of alanine aminotransaminase, aspartate transaminase, inflammatory cytokines (e.g., tumor necrosis factor α and interleukin-6), chemokines (e.g., MCP1/CCL2) and inflammatory cell (e.g., monocytes and neutrophils) infiltration. Moreover, it was found that the autophagy activity in Rnf115-/- livers was increased, which resulted in the removal of damaged mitochondria and hepatocyte apoptosis. However, the administration of adeno-associated virus Rnf115 or autophagy inhibitor 3-MA impaired autophagy and aggravated liver injury in Rnf115-/- mice with ALI. Further experiments proved that RNF115 interacts with LC3B, downregulates LC3B protein levels and cell autophagy. Additionally, Rnf115 deletion inhibited M1 type macrophage activation via NF-κB and Jnk signaling pathways. Elimination of macrophages narrowed the difference in liver damage between Rnf115+/+ and Rnf115-/- mice, indicating that macrophages were linked in the ALI induced by LPS/D-GalN. Collectively, for the first time, we have proved that Rnf115 inactivation ameliorated LPS/D-GalN-induced ALI in mice by promoting autophagy and attenuating inflammatory responses. This study provides new evidence for the involvement of autophagy mechanisms in the protection against acute liver injury.

Dietary docosahexaenoic acid reduces fat deposition and alleviates liver damage induced by D-galactosamine and lipopolysaccharides in Nile tilapia (Oreochromis niloticus)

Liver health is important to maintain survival and growth of fish. Currently, the role of dietary docosahexaenoic acid (DHA) in improving fish liver health is largely unknown. This study investigated the role of DHA supplementation in fat deposition and liver damage caused by D-galactosamine (D-GalN) and lipopolysaccharides (LPS) in Nile tilapia (Oreochromis niloticus). Four diets were formulated as control diet (Con), Con supplemented with 1 % DHA, 2 % DHA and 4 % DHA diets, respectively. The diets were fed to 25 Nile tilapia (2.0 ± 0.1 g, average initial weight) in triplicates for four weeks. After the four weeks, 20 fish in each treatment were randomly selected and injected with a mixture of 500 mg D-GalN and 10 μL LPS per mL to induce acute liver injury. The results showed that the Nile tilapia fed on DHA diets decreased visceral somatic index, liver lipid content and serum and liver triglyceride concentrations than those fed on the Con diet. Moreover, after D-GalN/LPS injection, the fish fed on DHA diets decreased alanine aminotransferase and aspartate transaminase activities in the serum. The results of liver qPCR and transcriptomics assays together showed that the DHA diets feeding improved liver health by downregulating the expression of the genes related to toll-like receptor 4 (TLR4) signaling pathway, inflammation and apoptosis. This study indicates that DHA supplementation in Nile tilapia alleviates the liver damage caused by D-GalN/LPS through increasing lipid catabolism, decreasing lipogenesis, TLR4 signaling pathway, inflammation, and apoptosis. Our study provides novel knowledge on the role of DHA in improving liver health in cultured aquatic animals for sustainable aquaculture.

The Anti-inflammatory Effects of Isoflavonoids from Radix Astragali in Hepatoprotective Potential against LPS/D-gal-induced Acute Liver Injury

Radix Astragali (RA) is an important Traditional Chinese Medicine widely used in the treatment of various diseases, such as pneumonia, atherosclerosis, diabetes, kidney and liver fibrosis. The role of isoflavonoids from RA in the treatment of liver injury remains unclear. The study aimed to explore hepatoprotective and anti-inflammatory effects of isoflavonoids from Astragalus mongholicus. Network pharmacological analysis showed that RA had a multi-target regulating effect on alleviating liver injury and inhibiting inflammation through its active ingredients, among which isoflavones were closely related to its key molecular targets. The anti-inflammatory and liver protection effects of isoflavonoids of RA were investigated using lipopolysaccharide (LPS)-induced RAW 264.7 cells in vitro and LPS/D-galactosamine (D-gal)-induced acute liver injury mice in vivo. The experimental results showed that methylnissolin (ML) and methylnissolin-3-O-β-D-glucoside (MLG) presented more notable anti-inflammatory effects. Both of them suppressed the release of pro-inflammatory cytokines, such as iNOS, COX-2, IL-1β, IL-6, and TNF-α in LPS-stimulated RAW 264.7 cells. In vivo investigation demonstrated that ML markedly meliorated liver injury in LPS/D-gal-induced mice. Western blot results revealed that ML and MLG down-regulated the expression of proinflammatory cytokines via NF-κB signaling pathway. The isoflavonoids, methylnissolin (ML), and methylnissolin-3-O-β-D-glucoside (MLG), play a vital role in the hepatoprotective and anti-inflammatory effects of RA.

Combination of Phycocyanin, Zinc, and Selenium Improves Survival Rate and Inflammation in the Lipopolysaccharide-Galactosamine Mouse Model

Sepsis is related to systemic inflammation and oxidative stress, the primary causes of death in intensive care units. Severe functional abnormalities in numerous organs can arise due to sepsis, with acute lung damage being the most common and significant morbidity. Spirulina, blue-green algae with high protein, vitamins, phycocyanin, and antioxidant content, shows anti-inflammatory properties by decreasing the release of cytokines. In addition, zinc (Zn) and selenium (Se) act as an antioxidant by inhibiting the oxidation of macromolecules, as well as the inhibition of the inflammatory response. The current study aimed to examine the combined properties of Zn, Se, and phycocyanin oligopeptides (ZnSePO) against lipopolysaccharide-D-galactosamine (LPS-GalN)-induced septic lung injury through survival rate, inflammatory, and histopathological changes in Balb/c mice. A total of 30 mice were allocated into three groups: normal control, LPS-GalN (100 ng of LPS plus 8 mg of D-galactosamine), LPS-GalN + ZnSePO (ZnPic, 52.5 µg/mL; SeMet, 0.02 µg/mL; and phycocyanin oligopeptide (PO), 2.00 mg/mL; at 1 h before the injection of LPS-GalN). Lung tissue from mice revealed noticeable inflammatory reactions and typical interstitial fibrosis after the LPS-GalN challenge. LPS-GalN-induced increased mortality rate and levels of IL-1, IL-6, IL-10, TGF-β, TNF-α, and NF-κB in lung tissue. Moreover, treatment of septic mice LPS-GalN + ZnSePO reduced mortality rates and inflammatory responses. ZnSePO considerably influenced tissue cytokine levels, contributing to its capacity to minimize acute lung injury (ALI) and pulmonary inflammation and prevent pulmonary edema formation in LPS-GalN-injected mice. In conclusion, ZnSePO treatment enhanced the survival rate of endotoxemia mice via improving inflammation and oxidative stress, indicating a possible therapeutic effect for patients with septic infections.

β-Carotene Protects Mice against Lipopolysaccharide and D-Galactosamine Induced Acute Liver Injury via Regulation of NF-κB, MAPK, and Nrf2 Signaling

Acute liver injury (ALI), posing a serious threaten to our life, has emerged as a public health issue around the world. β-carotene has plenty of pharmacologic effects, such as anti-inflammatory, antioxidant, and antitumor activities. In this study, we focused on studying the protective role and potential molecular mechanisms of β-carotene against D-galactosamine (D-GalN) and lipopolysaccharide (LPS) induced ALI. Our results indicated that β-carotene pretreatment effectively hindered abnormal changes induced by LPS/D-GalN in liver histopathology. Meanwhile, serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were downgraded with β-carotene pretreatment. β-carotene pretreatment also decreased malondialdehyde content and myeloperoxidase activity, increased glutathione peroxidase and superoxide dismutase levels, and reduced the levels of tumor necrosis factor-a (TNF-α) and interleukin 6 (IL-6) in liver tissues. Further investigations found that β-carotene mediated multiple signaling pathways in LPS/D-GalN-induced ALI, inhibiting NF-κB and MAPK signaling and upregulating the expression of Nrf2 and HO-1 proteins. All findings indicate that β-carotene appears to protect mice against LPS/D-GalN induced ALI by reducing oxidative stress and inflammation, possibly via regulating NF-κB, MAPK, and Nrf2 signaling.

Hepatocyte Bcl-3 protects from death-receptor mediated apoptosis and subsequent acute liver failure

Acute liver failure (ALF) is a rare entity but exhibits a high mortality. The mechanisms underlying ALF are not completely understood. The present study explored the role of the hepatic B cell leukemia-3 (Bcl-3), a transcriptional regulator of nuclear factor-kappa B (NF-κB), in two independent models of ALF. We employed a recently developed transgenic mouse model in a C57BL6/J background comparing wild-type (WT) and transgenic littermates with hepatocyte-specific overexpression of Bcl-3 (Bcl-3Hep) in the ALF model of d-galactosamine (d-GalN) and lipopolysaccharide (LPS). Additionally, the apoptosis-inducing CD95 (FAS/APO-1)-ligand was explored. Bcl-3Hep mice exhibited a significant protection from ALF with decreased serum transaminases, decreased activation of the apoptotic caspases 8, 9, and 3, lower rates of oxidative stress, B-cell lymphoma 2 like 1 (BCL2L1/BCL-XL) degradation and accompanying mitochondrial cytochrome c release, and ultimately a decreased mortality rate from d-GalN/LPS compared to WT mice. d-GalN/LPS treatment resulted in a marked inflammatory cytokine release and stimulated the activation of signal transducer and activator of transcription (STAT) 3, c-Jun N-terminal kinases (JNK) and extracellular signal-regulated kinase (ERK) signaling comparably in the hepatic compartment of Bcl-3Hep and WT mice. However, in contrast to the WT, Bcl-3Hep mice showed a diminished rate of IkappaB kinase-beta (IKK-β) degradation, persistent receptor interacting protein kinase (RIPK) 1 function and thus prolonged cytoprotective nuclear factor-kappa B (NF-κB) p65 signaling through increased p65 stability and enhanced transcription. Likewise, Bcl-3 overexpression in hepatocytes protected from ALF with massive hepatocyte apoptosis induced by the anti-FAS antibody Jo2. The protection was also linked to IKK-β stabilization. Overall, our study showed that Bcl-3 rendered hepatocytes more resistant to hepatotoxicity induced by d-GalN/LPS and FAS-ligand. Therefore, Bcl-3 appears to be a critical regulator of the dynamics in ALF through IKK-β.

Fibroblast growth factor 9 attenuates sepsis-induced fulminant hepatitis in mice

Sepsis-induced fulminant hepatitis (FH) is a fatal syndrome that has a worse prognosis in clinical practice. Hence, seeking effective agents for sepsis-induced FH treatment is urgently needed. Fibroblast growth factors (FGFs) are vital for tissue homeostasis and damage repair in various organs including the liver. Our study aims to investigate the protective effects and potential mechanisms of FGF9 on lipopolysaccharide (LPS)/D-galactosamine (D-Gal)-induced FH in mice. We found that pre-treatment with FGF9 exhibited remarkable hepaprotective effects on liver damage caused by LPS/D-Gal, as manifested by the concomitant decrease in mortality and serum aminotransferase activities, and the attenuation of hepatocellular apoptosis and hepatic histopathological abnormalities in LPS/D-Gal-intoxicated mice. We further found that FGF9 alleviated the infiltration of neutrophils into the liver, and decreased the serum levels of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in LPS/D-Gal-challenged mice. These effects can be explained at least in part by the inhibition of NF-κB signaling pathway. Meanwhile, FGF9 enhanced the antioxidative defense system in mice livers by upregulating the expression of NRF-2-related antioxidative enzymes, including glutamate-cysteine ligase catalytic subunit (GCLC), NAD(P)H: quinone oxidoreductase 1 (NQO-1), and heme oxygenase-1 (HO-1). These data indicate that FGF9 represents a promising therapeutic drug for ameliorating sepsis-induced FH via its anti-apoptotic and anti-inflammatory capacities.

Optimization of Metabolic Oligosaccharide Engineering with Ac4GalNAlk and Ac4GlcNAlk by an Engineered Pyrophosphorylase

Metabolic oligosaccharide engineering (MOE) has fundamentally contributed to our understanding of protein glycosylation. Efficient MOE reagents are activated into nucleotide-sugars by cellular biosynthetic machineries, introduced into glycoproteins and traceable by bioorthogonal chemistry. Despite their widespread use, the metabolic fate of many MOE reagents is only beginning to be mapped. While metabolic interconnectivity can affect probe specificity, poor uptake by biosynthetic salvage pathways may impact probe sensitivity and trigger side reactions. Here, we use metabolic engineering to turn the weak alkyne-tagged MOE reagents Ac₄GalNAlk and Ac₄GlcNAlk into efficient chemical tools to probe protein glycosylation. We find that bypassing a metabolic bottleneck with an engineered version of the pyrophosphorylase AGX1 boosts nucleotide-sugar biosynthesis and increases bioorthogonal cell surface labeling by up to two orders of magnitude. A comparison with known azide-tagged MOE reagents reveals major differences in glycoprotein labeling, substantially expanding the toolbox of chemical glycobiology.

Francisella FlmX broadly affects lipopolysaccharide modification and virulence

The outer membrane protects Gram-negative bacteria from the host environment. Lipopolysaccharide (LPS), a major outer membrane constituent, has distinct components (lipid A, core, O-antigen) generated by specialized pathways. In this study, we describe the surprising convergence of these pathways through FlmX, an uncharacterized protein in the intracellular pathogen Francisella. FlmX is in the flippase family, which includes proteins that traffic lipid-linked envelope components across membranes. flmX deficiency causes defects in lipid A modification, core remodeling, and O-antigen addition. We find that an F. tularensis mutant lacking flmX is >1,000,000-fold attenuated. Furthermore, FlmX is required to resist the innate antimicrobial LL-37 and the antibiotic polymyxin. Given FlmX's central role in LPS modification and its conservation in intracellular pathogens Brucella, Coxiella, and Legionella, FlmX may represent a novel drug target whose inhibition could cripple bacterial virulence and sensitize bacteria to innate antimicrobials and antibiotics.

Deletion or inhibition of SphK1 mitigates fulminant hepatic failure by suppressing TNFα-dependent inflammation and apoptosis

Acute liver failure (ALF) causes severe liver dysfunction that can lead to multi-organ failure and death. Previous studies suggest that sphingosine kinase 1 (SphK1) protects against hepatocyte injury, yet not much is still known about its involvement in ALF. This study examines the role of SphK1 in D-galactosamine (GalN)/lipopolysaccharide (LPS)-induced ALF, which is a well-established experimental mouse model that mimics the fulminant hepatitis. Here we report that deletion of SphK1, but not SphK2, dramatically decreased GalN/LPS-induced liver damage, hepatic apoptosis, serum alanine aminotransferase levels, and mortality rate compared to wild-type mice. Whereas GalN/LPS treatment-induced hepatic activation of NF-κB and JNK in wild-type and SphK2-/- mice, these signaling pathways were reduced in SphK1-/- mice. Moreover, repression of ALF in SphK1-/- mice correlated with decreased expression of the pro-inflammatory cytokine TNFα. Adoptive transfer experiments indicated that SphK1 in bone marrow-derived infiltrating immune cells but not in host liver-resident cells, contribute to the development of ALF. Interestingly, LPS-induced TNFα production was drastically suppressed in SphK1-deleted macrophages, whereas IL-10 expression was markedly enhanced, suggesting a switch to the anti-inflammatory phenotype. Finally, treatment with a specific SphK1 inhibitor ameliorated inflammation and protected mice from ALF. Our findings suggest that SphK1 regulates TNFα secretion from macrophages and inhibition or deletion of SphK1 mitigated ALF. Thus, a potent inhibitor of SphK1 could potentially be a therapeutic agent for fulminant hepatitis.

Tryptophan-galactosylamine conjugates inhibit and disaggregate amyloid fibrils of Aβ42 and hIAPP peptides while reducing their toxicity

Self-assembly of proteins into amyloid fibrils is a hallmark of various diseases, including Alzheimer's disease (AD) and Type-2 diabetes Mellitus (T2DM). Aggregation of specific peptides, like Aβ42 in AD and hIAPP in T2DM, causes cellular dysfunction resulting in the respective pathology. While these amyloidogenic proteins lack sequence homology, they all contain aromatic amino acids in their hydrophobic core that play a major role in their self-assembly. Targeting these aromatic residues by small molecules may be an attractive approach for inhibiting amyloid aggregation. Here, various biochemical and biophysical techniques revealed that a panel of tryptophan-galactosylamine conjugates significantly inhibit fibril formation of Aβ42 and hIAPP, and disassemble their pre-formed fibrils in a dose-dependent manner. They are also not toxic to mammalian cells and can reduce the cytotoxicity induced by Aβ42 and hIAPP aggregates. These tryptophan-galactosylamine conjugates can therefore serve as a scaffold for the development of therapeutics towards AD and T2DM.

Characterization and distribution of sialic acids in human testicular seminoma

Aberrant content of sialic acids (Sias) has been observed in various human cancer types in different organs. Sias have been implicated in cancerous transformation, invasiveness and metastasis, and in the escaping of cancer cells from immune surveillance. Indeed, Sias are commonly regarded as important biomarkers to distinguish cancer cells from their healthy counterparts. However, scarce and not exhaustive investigations have been performed on Sia content in testicular cancers and, in particular, in seminoma, one of the most common malignant testicular tumors. Hence, the aim of this study was to investigate the content and distribution of Sias with different glycosidic linkage, namely α2,3 and α2,6 galactose- or N-acetyl-galactosamine-linked Sias and polymeric Sia (polySia), in the germinal and stromal components of human testes affected by seminoma compared to normal testicular tissue. Structural changes in seminoma tissue were examined using hematoxylin-eosin staining. α2,3 and α2,6 linked Sias were evaluated by lectin histochemistry (Maackia amurensis agglutinin (MAA) and Sambucus nigra agglutinin (SNA)), while confocal immunofluorescence was used for polySia detection. Histopathological findings in seminoma tissue included loss of seminiferous tubules replaced by clusters of uniform polygonal cells with a clear cytoplasm, bundles of fibrotic tissue, numerous microvessels and some atrophic tubules. The content of α2,3 and α2,6 linked Sias was lost in almost all seminoma components respect to normal tissue, with the exception of microvessels in which it was higher. On the contrary, polySia level was increased in all the seminoma components compared to normal testicular tissue. Our findings suggest that an aberrant content of different Sias might have important and differential roles in seminoma development and progression. In particular, polySia might be implicated in seminoma progression by promoting cancer invasiveness and regulating the cross-talk between cancer cells, reactive stroma and vessels. Thus, the possibility that polySia might represent an important biomarker for seminoma deserves further investigation.

Barbaloin loaded polydopamine-polylactide-TPGS (PLA-TPGS) nanoparticles against gastric cancer as a targeted drug delivery system: Studies in vitro and in vivo

Gastric cancer is the third leading cause of cancer-associated death worldwide. Although a decrease in its incidence is observed, gastric cancer still poses a major clinical challenge due to poor prognosis and limited treatments. Barbaloin (BBL) is a main medicinal composition of the Chinese traditional medicine aloe vera. BBL has various bioactivities, including anti-oxidant, anti-inflammatory and anti-tumor properties. Polydopamine (pD)-based surface modification is easy to functionalize polymeric nanoparticles (NPs) surfaces with ligands and/or additional polymeric layers. In the present study, BBL-loaded formulations was developed with pD-modified NPs, which was synthesized by polylactide-TPGS (PLA-TPGS) (pD-PLA-TPGS/NPs). And galactosamine (Gal) was conjugated on the prepared NPs (Gal-pD-PLA-TPGS/NPs) for targeting the gastric cancer cells. Here, we found that BBL-loaded Gal-pD-PLA-TPGS/NPs showed the highest cellular uptake efficacy in gastric cancer cells. Gal-pD-PLA-TPGS/NPs more significantly reduced the gastric cancer cell viability. Further, greater apoptosis, autophagy and ROS generation was induced by Gal-pD-PLA-TPGS/NPs in gastric cancer cells. Additionally, compared to the other two NPs, Gal-pD-PLA-TPGS/NPs most markedly decreased ATP levels in gastric cancer cells. In vivo, Gal-pD-PLA-TPGS/NPs were specifically targeted to tumor site. Moreover, Gal-pD-PLA-TPGS/NPs exhibited the most anti-tumor effects, as evidenced by the lowest tumor volume and tumor weight. Of note, there was no significant difference was observed in body and liver weight, as well as the histological changes in major organs isolated from each group of mice. Together, the findings indicated that BBL-loaded Gal-pD-PLA-TPGS/NPs could be targeted to gastric cancer cells to suppress tumor progression without toxicity.

IRF3 is an important molecule in the UII/UT system and mediates immune inflammatory injury in acute liver failure

The urotensin II/urotensin receptor (UII/UT) system can mediate inflammatory liver injury in acute liver failure (ALF); however; the related mechanism is not clear. In this study, we confirmed that lipopolysaccharide/D-galactosamine (LPS/D-GalN) induced up-regulation of liver interferon regulatory factor 3 (IRF3) in ALF mice, whereas the UT antagonist urantide inhibited the up-regulated liver IRF3. LPS stimulation induced IRF3 transcription and nuclear translocation and promoted the secretion of interleukin-6 (IL-6), interferon (IFN)-β, and IFN-γ in Kupffer cells (KCs); these effects in LPS-stimulated KCs were inhibited by urantide. Knockdown of IRF3 using an adenovirus expressing an IRF3 shRNA inhibited IFN-β transcription and secretion as well as tumor necrosis factor (TNF)-α and IL-1β secretion from LPS-stimulated KCs; additionally, IL-10 transcription and secretion were promoted in response to LPS. However, LPS-stimulated TNF-α and IL-1β mRNA was not affected in the KCs. The IRF3 shRNA also did not have a significant effect on the NF-κB p65 subunit and p38MAPK protein phosphorylation levels in the nuclei of LPS-stimulated KCs. Therefore, IRF3 expression and activation depended on the signal transduction of the UII/UT system, and played important roles in UII/UT-mediated immune inflammatory injury in the liver but did not affect NF-κB and p38 MAPK activity.

Transferase Activity of Lactobacillal and Bifidobacterial β-Galactosidases with Various Sugars as Galactosyl Acceptors

The β-galactosidases from Lactobacillus reuteri L103 (Lreuβgal), Lactobacillus delbrueckii subsp. bulgaricus DSM 20081 (Lbulβgal), and Bifidobacterium breve DSM 20281 (Bbreβgal-I and Bbreβgal-II) were investigated in detail with respect to their propensity to transfer galactosyl moieties onto lactose, its hydrolysis products D-glucose and D-galactose, and certain sugar acceptors such as N-acetyl-D-glucosamine (GlcNAc), N-acetyl-D-galactosamine (GalNAc), and L-fucose (Fuc) under defined, initial velocity conditions. The rate constants or partitioning ratios (kNu/kwater) determined for these different acceptors (termed nucleophiles, Nu) were used as a measure for the ability of a certain substance to act as a galactosyl acceptor of these β-galactosidases. When using Lbulβgal or Bbreβgal-II, the galactosyl transfer to GlcNAc was 6 and 10 times higher than that to lactose, respectively. With lactose and GlcNAc used in equimolar substrate concentrations, Lbulβgal and Bbreβgal-II catalyzed the formation of N-acetyl-allolactosamine with the highest yields of 41 and 24%, respectively, as calculated from the initial GlcNAc concentration.

The presence of a galactosamine substituent on the arabinogalactan of Mycobacterium tuberculosis abrogates full maturation of human peripheral blood monocyte-derived dendritic cells and increases secretion of IL-10

Slow-growing and pathogenic Mycobacterium spp. are characterized by the presence of galactosamine (GalN) that modifies the interior branched arabinosyl residues of the arabinogalactan (AG) that is a major heteropolysaccharide cell wall component. The availability of null mutants of the polyprenyl-phospho-N-acetylgalactosaminyl synthase (Rv3631, PpgS) and the (N-acetyl-) galactosaminyl transferase (Rv3779) of Mycobacterium tuberculosis (Mtb) has provided a means to elucidate the role of the GalN substituent of AG in terms of host-pathogen interactions. Comparisons of treating human peripheral blood monocyte-derived dendritic cells (hPMC-DCs) with wild-type, Rv3631 and Rv3779 mutant strains of Mtb revealed increased expression of DC maturation markers, decreased affinity for a soluble DC-SIGN probe, reduced IL-10 secretion and increased TLR-2-mediated NF-κB activation among GalN-deficient Mtb strains compared to GalN-producing strains. Analysis of surface expression of a panel of defined or putative DC-SIGN ligands on both WT strains or either Rv3631 or Rv3779 mutant did not show significant differences suggesting that the role of the GalN substituent of AG may be to modulate access of the bacilli to immunologically-relevant receptor domains on DCs or contribute to higher ordered pathogen associated molecular pattern (PAMP)/pattern recognition receptor (PRR) interactions rather than the GalN-AG components having a direct immunological effect per se.

Synthesis of zwitterionic 1,1'-glycosylphosphodiester: a partial structure of galactosamine-modified Francisella lipid A

Synthesis of a "double glycosidic" phosphodiester comprising anomeric centers of two 2-amino-2-deoxy-sugars is reported. The carbohydrate epitope of Francisella lipid A modified with α-d-galactosamine at the anomerically linked phosphate has been stereoselectively prepared and coupled to maleimide-activated bovine serum albumin via an amide-linked thiol-terminated spacer group. H-Phosphonate and phosphoramidite approaches have been explored for the coupling of 4,6-DTBS-2-azido-protected GalN lactol and peracetylated spacer-equipped reducing βGlcN(1→6)GlcN disaccharide via phosphodiester linkage. Deprotection conditions preserving the integrity of the labile glycosidic zwitterionic phosphodiester were elaborated.

[Dynamic changes of soil amino sugar contents under drying and wetting cycle]

A soil incubation test was conducted to study the quantitative changes of three amino sugars (glucosamine, muramic acid, and galactosamine) derived from microbes under drying and wetting cycle, and to analyze the relative contribution of soil bacteria and fungi to the turnover of soil organic matter by using the measured glucosamine/muramic acid ratio. Under continuous wetting, the degradation of bacteria-derived muramic acid was faster than that of fungi-derived glucosamine, and the degradation rate of galactosamine was the lowest. Drying and wetting cycle altered the degradation characteristics of the three amino sugars. As compared with that under continuous wetting, the degradation rate of bacteria-derived muramic acid at the prophase of drying and wetting was faster than that of fungi-derived glucosamine, and, with the increasing frequency of drying and wetting cycle, the degradation rate of fungi-derived glucosamine was faster than that of bacteria-derived muramic acid. These results indicated that drying and wetting cycle changed the course of the microbial transformation of soil amino sugar-derived nitrogen.

(1)H-MRS can detect aberrant glycosylation in tumour cells: a study of the HeLa cell line

Glycosylation is the most abundant and diverse form of post-translational modification of proteins. Two types of glycans exist in glycoproteins: N-glycans and O-glycans often coexisting in the same protein. O-glycosylation is frequently found on secreted or membrane-bound mucins whose overexpression and structure alterations are associated with many types of cancer. Mucins have several cancer-associated structures, including high levels of Lewis antigens characterized by the presence of terminal fucose. The present study deals with the identification of MR signals from N-acetylgalactosamine and from fucose in HeLa cells by detecting a low-field signal in one-dimensional (1D) spectra assigned to the NH of N-acetylgalactosamine and some cross peaks assigned to fucose in two-dimensional (2D) spectra. The increase of Golgi pH by treatment with ammonium chloride allowed the N-acetylgalactosamine signal assignment to be confirmed. Behaviour of MR peak during cell growth and comparison with studies from literature taken together made it possible to have more insight into the relationship between aberrantly processed mucin and the presence of non-processed N-acetylgalactosamine residues in HeLa cells. Fucose signals, tentatively ascribed to residues bound to galactose and to N-acetylglucosamine, are visible in both intact cell and perchloric acid spectra. Signals assigned to fucose bound to galactose are more evident in ammonium chloride-treated cells where structural changes of mucin-related Lewis antigens are expected as a result of the higher Golgi pH. A common origin for the N-acetylgalactosamine and fucose resonances attributing them to aberrantly processed mucin can be inferred from the present results.

[Amino sugars mineralization and its responses to exogenous substances in black soil of Northeast China]

By the method of intermittent leaching aerobic incubation, this paper studied the mineralization of three kinds of microbes-derived amino sugar (glucosamine, muramic acid, and galactosamine) in black soil of Northeast China, and the responses to glucose addition and glucose plus nitrogen amendment. The mineralization of the amino sugars was compound-specific. During incubation period, the content of muramic acid decreased by 25.4%, while that of glucosamine decreased by 7.1%, suggesting that bacteria-derived muramic acid was more inclined to be mineralized, compared with fungi-originated glucosamine. However, the mineralized amount of glucosamine (68.4 mg x kg(-1)) was greater than that of muramic acid (15.4 mg x kg(-1)). Both glucose addition and glucose plus nitrogen amendment improved the contents of glucosamine and muramic acid significantly, but the effect varied. The mineralization of galactosamine was much slower, and less affected by exogenous substances addition, indicating that galactosamine was more stable in test soil.

Identification and preliminary validation of novel biomarkers of acute hepatic ischaemia/reperfusion injury using dual-platform proteomic/degradomic approaches

Hepatic ischaemia/reperfusion (I/R), a major cause of liver damage associated with multiple trauma, haemorrhagic and septic shock, and liver transplantation, contributes significantly to multiple organ failure. Development of novel sensitive biomarkers that detect early stages of liver damage is vital for effective management and treatment of ischaemic liver injury. By using high-throughput immunoblotting and cation-anion exchange chromatography/reversed-phase liquid chromatography-tandem mass-spectrometry, we identified several hepatic proteins, including argininosuccinate synthase (ASS) and estrogen sulfotransferase (EST-1), which were degraded in the liver and rapidly released into circulation during I/R injury. ASS accumulated in serum within 10 min, reached a steady state at 30 min, and persisted up until 3 h after reperfusion following 30 min of total hepatic ischaemia. EST-1 appeared rapidly in blood and attained maximum within 1 hour followed by a decline at 3 h of reperfusion. No ASS or EST-1 protein was detected in serum of control or sham operated rats. ASS and EST-1 exhibited greater sensitivity and specificity toward I/R liver injury as compared with alanine aminotransferase (ALT), an established marker of hepatocellular necrosis. In contrast, serum ASS and EST-1 were undetectable in rats with chronic alcoholic liver disease, while the levels of ALT protein were significantly increased. In addition, ASS, but not EST-1 or ALT accumulated in blood only 6 h after treatment with hepatotoxic combination of lipopolysaccharide and D-galactosamine. These data demonstrate the utility of ASS and EST-1 as novel sensitive and specific biomarkers of acute liver ischaemic injury for prospective clinical studies.

A self-quenched galactosamine-serum albumin-rhodamineX conjugate: a "smart" fluorescent molecular imaging probe synthesized with clinically applicable material for detecting peritoneal ovarian cancer metastases

PURPOSE

Fluorophore activation after cellular internalization of a targeted fluorescently labeled conjugate is an effective molecular imaging strategy to increase target-to-background ratios. The D-galactose receptor on ovarian cancer cells has been used to target self-quenched avidin-rhodamineX conjugates in which the avidin component binds to D-galactose receptor and the rhodamines are optically activated by dequenching only after cellular internalization. As a nonimmunogenic alternative of avidin, galactosamine-conjugated serum albumin (GmSA) targets the D-galactose receptor with higher binding affinity and has more conjugation sites available for rhodamineX than avidin.

EXPERIMENTAL DESIGN

GmSA was conjugated with 20 rhodamineX molecules (GmSA-20ROX) to create a self-quenching complex, which was compared with a conjugate consisting of GmSA and a single rhodamineX (GmSA-1ROX) in ex vivo chemical activation characteristics, intracellular activation, and in vivo molecular imaging for detecting peritoneal micrometastases of SHIN3 ovarian cancer.

RESULTS

GmSA-20ROX was five times brighter than GmSA-1ROX when incubated with SHIN3 ovarian cancer cells for 3 h. Submillimeter SHIN3 ovarian cancer implants in the peritoneal cavity were clearly visualized in vivo with spectral fluorescence imaging due to the high tumor-to-background ratio. The sensitivity and specificity of GmSA-20ROX for implant detection were determined by colocalization of the rhodamineX emission with red fluorescent protein expressed constitutively in the SHIN3 tumor implants. Among 336 lesions, sensitivity and specificity were 99%/99%, respectively, for GmSA-20ROX, whereas the results for GmSA-1ROX were only 24%/100% (n = 388), respectively, for lesions approximately 0.8 mm or greater in diameter.

CONCLUSION

Self-quenched GmSA-20ROX is more efficient than previous d-galactose-targeted fluorescent conjugates.

Concentrations of monosaccharides and their amino and alcohol derivatives in human preovulatory follicular fluid

The study purpose was to compare sugar and polyol concentrations in preovulatory ovarian follicular fluid (FF) with those in the circulation. Samples of FF and peripheral venous blood were obtained after an overnight fast from 14 women attending an IVF program. High performance liquid chromatography measurements of seven polyols, two aminohexoses and four hexoses were the main outcome measures. Glucose concentrations in FF and plasma were 2781.26 +/- 205.64 and 4431.25 +/- 65.17 microM, respectively (P < 0.001). Mannose concentration in FF was 38.99 +/- 3.33 microM, significantly lower than plasma concentration (55.38 +/- 2.29 microM; P < 0.001). A concentration gradient from plasma to FF was also significant for glycerol (99.41 +/- 8.47 versus 74.32 +/- 6.54 microM; P < 0.002), galactose (31.69 +/- 1.58 versus 26.73 +/- 1.93 microM; P < 0.01) and galactosamine (11.49 +/- 0.69 versus 6.38 +/- 0.59 microM; P < 0.001). The plasma-to-FF concentration difference was greatest for glucose (1649.99 +/- 204.09 microM). There was a significant correlation between plasma and FF concentrations for galactose and glycerol. This study supports a substantial utilization of glucose by the oocyte/granulosa cells complex, and documents a significant concentration gradient from plasma to FF for glycerol, mannose, galactose and galactosamine. These plasma-FF differences may reflect both utilization of these carbohydrates by the cells of the preovulatory ovarian follicle and/or transport characteristics of these cells.

Hydrogen peroxide derived from amine oxidation mediates the interaction between aminosugars and semicarbazide-sensitive amine oxidase

Semicarbazide-sensitive amine oxidase (SSAO) also functions as a vascular-adhesion protein (VAP-1). The nature of the target site on lymphocytes to which endothelial-cell SSAO/VAP-1 binds is unknown. We have shown that amino sugars (galactosamine, glucosamine and mannosamine), which are not SSAO substrates, can bind to the enzyme as reversible inhibitors. Thus, they serve as a model system in which to study the interaction process. Binding occurred during substrate (benzylamine) oxidation but not when the amino sugar was incubated, for extended periods, with SSAO alone. These results suggest that one, or more of the products of the SSAO-catalysed amine oxidation might be necessary for the inhibitory process to occur. Two of the reaction products of benzylamine oxidation, benzaldehyde and ammonia were found to have no effect on the inhibition of SSAO by galactosamine. Preincubation of the enzyme with galactosamine plus H(2)O(2) was, however, found to result in time-dependent inhibition. This is not a result of the non-enzymic reaction between H(2)O(2) and the amino sugar, since preincubation of galactosamine with H(2)O(2) alone, for extended periods, did not give rise to an inhibitory species. The amount of exogenously added H(2)O(2) necessary for inhibition was very much greater than that formed during substrate oxidation. These results suggest that the H(2)O(2) formed as a product of the SSAO-catalysed oxidation reaction is more efective in promoting the binding of amino sugars.

A metabonomics study of the hepatotoxicants galactosamine, methylene dianiline and clofibrate in rats

The efficacy of high-resolution (1)H nuclear magnetic resonance ((1)H-NMR) spectroscopy-based metabonomics was studied in a model of rat liver toxicity. Hepatotoxicities were induced in male rats using methylene dianiline, clofibrate and galactosamine. Twenty-four-hr urine from days 1 to 5 after treatment were subjected to (1)H-NMR evaluation of the biochemical effects. Blood were also taken at Days 2, 3 and 5 to examine biochemical changes associated with hepatotoxicities, and histopathological changes were evaluated at termination. Increases in liver enzymes were observed in animals treated with methylene dianiline or galactosamine, and histopathological analysis revealed changes associated with hepatobiliary damage and hepatocellular necrosis in methylene dianiline- and galactosamine-treated animals, respectively. Principal component analysis and statistical Spotfire analyses were used to visualize similarities and differences in urine biochemical profiles produced by (1)H-NMR spectra. The biochemical effects of methylene dianiline and galactosamine were characterized by elevated levels of glucose, fructose, beta-hydroxybutyrate, alanine, acetoacetate, lactate and creatine and decreased levels of hippurate, 2-oxoglutarate, citrate, succinate, trimethylamine-N-oxide, taurine and N-acetylglutamate in rat urine. Clofibrate treatment elevated the levels of N-methylnicotinamide and 3,4-dihydroxymandelate and decreased the levels of 2-oxoglutarate and N-acetylaspartate. This work shows that combinations of (1)H-NMR and pattern recognition are powerful tools in the evaluation of the biochemical effects of xenobiotics in liver.

Structure and biosynthesis of free lipid A molecules that replace lipopolysaccharide in Francisella tularensis subsp. novicida

Francisella tularensis subsp. novicida U112 phospholipids, extracted without hydrolysis, consist mainly of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, and two lipid A species, designated A1 and A2. These lipid A species, present in a ratio of 7:1, comprise 15% of the total phospholipids, as judged by 32Pi labeling. Although lipopolysaccharide is detectable in F. tularensis subsp. novicida U112, less than 5% of the total lipid A is covalently linked to it. A1 and A2 were analyzed by electrospray ionization and matrix-assisted laser desorption ionization mass spectrometry, gas chromatography/mass spectrometry, and NMR spectroscopy. Both compounds are disaccharides of glucosamine, acylated with primary 3-hydroxystearoyl chains at positions 2, 3, and 2' and a secondary palmitoyl residue at position 2'. Minor isobaric species and some lipid A molecules containing a 3-hydroxypalmitoyl chain in place of 3-hydroxystearate are also present. The 4'- and 3'-positions of A1 and A2 are not derivatized, and 3-deoxy-d-manno-octulosonic acid (Kdo) is not detectable. The 1-phosphate groups of both A1 and A2 are modified with an alpha-linked galactosamine residue, as shown by NMR spectroscopy and gas chromatography/mass spectrometry. An alpha-linked glucose moiety is attached to the 6'-position of A2. The lipid A released by mild acid hydrolysis of F. tularensis subsp. novicida lipopolysaccharide consists solely of component A1. F. tularensis subsp. novicida mutants lacking the arnT gene do not contain a galactosamine residue on their lipid A. Formation of free lipid A in F. tularensis subsp. novicida might be initiated by an unusual Kdo hydrolase present in the membranes of this organism.

Red potato extract protects from D-galactosamine-induced liver injury in rats

The protective effects of red potato extract (RPE) as to liver damage were determined in D-galactosamine (GalN)-intoxicated rats. Increases in serum aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase activities, all of which were induced by GalN injection, decreased in RPE administered rats, suggesting that RPE acts as a functional food showing anti-hepatotoxicity.

Sequence analyses of fimbriae subunit FimA proteins on Actinomyces naeslundii genospecies 1 and 2 and Actinomyces odontolyticus with variant carbohydrate binding specificities

Background

Actinomyces naeslundii genospecies 1 and 2 express type-2 fimbriae (FimA subunit polymers) with variant Galβ binding specificities and Actinomyces odontolyticus a sialic acid specificity to colonize different oral surfaces. However, the fimbrial nature of the sialic acid binding property and sequence information about FimA proteins from multiple strains are lacking.

Results

Here we have sequenced fimA genes from strains of A.naeslundii genospecies 1 (n = 4) and genospecies 2 (n = 4), both of which harboured variant Galβ-dependent hemagglutination (HA) types, and from A.odontolyticus PK984 with a sialic acid-dependent HA pattern. Three unique subtypes of FimA proteins with 63.8–66.4% sequence identity were present in strains of A. naeslundii genospecies 1 and 2 and A. odontolyticus. The generally high FimA sequence identity (>97.2%) within a genospecies revealed species specific sequences or segments that coincided with binding specificity. All three FimA protein variants contained a signal peptide, pilin motif, E box, proline-rich segment and an LPXTG sorting motif among other conserved segments for secretion, assembly and sorting of fimbrial proteins. The highly conserved pilin, E box and LPXTG motifs are present in fimbriae proteins from other Gram-positive bacteria. Moreover, only strains of genospecies 1 were agglutinated with type-2 fimbriae antisera derived from A. naeslundii genospecies 1 strain 12104, emphasizing that the overall folding of FimA may generate different functionalities. Western blot analyses with FimA antisera revealed monomers and oligomers of FimA in whole cell protein extracts and a purified recombinant FimA preparation, indicating a sortase-independent oligomerization of FimA.

Conclusion

The genus Actinomyces involves a diversity of unique FimA proteins with conserved pilin, E box and LPXTG motifs, depending on subspecies and associated binding specificity. In addition, a sortase independent oligomerization of FimA subunit proteins in solution was indicated.

Activation of mitogen activated protein kinase (MAPK) during D-galactosamine intoxication in the rat liver

A significant increase in plasma glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase was observed 6 h after intraperitoneal administration of D-galactosamine (D-Galn). Three hours after administration of D-Galn, the vitamin C concentration in the liver decreased significantly compared to that in a control group and thereafter the hepatic vitamin C concentration remained at a significantly lower level. Phosphorylated JNK (c-Jun NH2-terminal kinase) and phosphorylated ERK (extracellular signal-regulated kinase) started increasing 3 h after D-Galn treatment and remained at a high level for 6-12 h after the treatment, while phosphorylated p38 MAPK increased significantly 6 h after D-Galn administration. These results indicated that oxidative stress and the activation of JNK and ERK took place almost simultaneously, followed by the activation of p38 MAPK.

Bone marrow progenitors are not the source of expanding oval cells in injured liver

Liver progenitor/oval cells differentiate into hepatocytes and biliary epithelial cells, repopulating the liver when the regenerative capacity of hepatocytes is impaired. Recent studies have shown that hematopoietic bone marrow (BM) stem/progenitor cells can give rise to hepatocytes in diseased/damaged liver. One study has reported that BM cells can transdifferentiate into liver progenitor/oval cells, but it has not been proven that the latter can repopulate the liver. To answer this question, we have lethally irradiated female DPP4(-) mutant F344 rats and transplanted them with 50 million wild-type male F344 BM cells. One month after transplantation, the recipient BM was reconstituted with male hematopoietic cells, determined by quantitative polymerase chain reaction using primers for Y chromosome-specific sry gene. In addition, DPP4(+) cells, single or in clusters and predominantly in the periportal region, were detected in all liver sections of recipient rats. Animals were subjected to the following three different liver injury protocols for activation and expansion of oval cells: D-galactosamine, retrorsine/partial hepatectomy (Rs/PH), and 2-acetylaminofluorene/partial hepatectomy (2-AAF/PH). In all three models, prominent expansion and accumulation of cytokeratin 19-positive (CK-19(+)) oval cells was observed. However, most of the DPP4(+) clusters dispersed over time, and their total number decreased. Very few oval cells (less than 1%) showed double DPP4/CK-19 labeling. None of the small hepatocytic clusters in the Rs/PH or 2-AAF/PH model were comprised of DPP4(+) cells. These data demonstrate that the sources of oval cells and small hepatocytes in the injured liver are endogenous liver progenitors and that they do not arise through transdifferentiation from BM cells.

Cellular addresses; step one in creating a glycocode

In this issue of Chemistry & Biology, a library screening approach reveals at least four types of enzymes that attach galactosamine to build cell surface mucin-type glycoproteins. A better molecular understanding of how these information-carrying oligosaccharides are created sets the stage for designing more selective inhibitors and potential therapeutics.

In vivo and in vitro cytokine modulatory activity of newly synthesised 2-aminotetraline derivatives

In the present study, the protective effect of newly synthesised 2-aminotetralines was investigated in murine models of toxic shock. A few derivatives protected mice against lethality induced by lipopolysaccharide from different bacterial strains and shock induced by staphylococcal enterotoxin B in mice sensitized by D-Galactosamine (D-Galn). Notably, one derivative, S(-)-2-amino-6-fluoro-7-methoxy-1,2,3,4 tetrahydronaphthalene hydrochloride (ST1214), was also effective when administered orally (30 mg kg-1) in a therapeutic regimen. ST1214 markedly inhibited the production of the proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), Interleukin-1beta (IL-1beta), Interleukin-12 (IL-12), interferon-gamma (IFN-gamma), as well as the inflammatory mediator nitric oxide (NO), and concurrently enhanced the production of the anti-inflammatory cytokine IL-10. Moreover, ST1214 dose-dependently reduced TNF-alpha production by human peripheral blood mononuclear cells and promonocytic THP-1 cells in vitro. In the latter, ST1214 was found to inhibit lipopolysaccharide-induced TNF-alpha secretion but not cytokine mRNA accumulation. These results suggest that the mechanism of action of ST1214 involves blockade of posttranscriptional events of TNF-alpha production, apparently independent of p38 and ERK kinase activity. These results show beneficial effects of 2-aminotetralines in murine shock models and indicate a distinct counter-regulatory activity in down-regulating proinflammatory cytokine response, and upregulating IL-10. One derivative, i.e., ST1214, can be regarded as a lead compound in the development of novel drugs effective in anti-inflammatory strategies.

The glycine analogue, aminomethanesulfonic acid, inhibits LPS-induced production of TNF-alpha in isolated rat Kupffer cells and exerts hepatoprotective effects in mice

The activation of Kupffer cells represents a central mechanism of liver injury involving the production of TNF-alpha. It is known that glycine prevents LPS-induced production of TNF-alpha in isolated Kupffer cells. In this study, the possibility that glycine analogues might affect Kupffer cells was investigated. As a result, aminomethanesulfonic acid (AMS) inhibited the production of TNF-alpha in LPS-stimulated Kupffer cells. Furthermore, LPS treatment caused a transient increase in intracellular calcium ([Ca(2+)](i)) which was blunted by AMS. Thus, the addition of AMS is protective against the LPS-induced increase [Ca(2+)](i) and subsequent production of TNF-alpha. Moreover, in vivo studies demonstrated that pretreatment of mice with AMS increased the rate of survival after injection with LPS/d-gal and reduced the TNF-alpha serum level and the mRNA level in the liver. These results indicate that intake of AMS attenuates the LPS-induced hepatotoxicity resulting from activation of Kupffer cells.

d-Hexosaminate production by oxidative fermentation

Microbial production of D-hexosaminate was examined by means of oxidative fermentation with acetic acid bacteria. In most strains of acetic acid bacteria, membrane-bound D-glucosamine dehydrogenase (synonymous with an alternative D-glucose dehydrogenase distinct from quinoprotein D-glucose dehydrogenase) oxidized D-hexosamines to the corresponding D-hexosaminates in a stoichiometric manner. Conversion of D-hexosamines to the corresponding D-hexosaminates was observed with growing cells of acetic acid bacteria, and D-hexosaminate was stably accumulated in the culture medium even though D-hexosamine was exhausted. Since the enzyme responsible is located on the outer surface of the cytoplasmic membrane, and the enzyme activity is linked to the respiratory chain of the organisms, resting cells, dried cells, and immobilized cells of acetic acid bacteria were effective catalysts for D-hexosaminate production. D-Mannosaminate and D-galactosaminate were also prepared for the first time by means of oxidative fermentation, and three different D-hexosaminates were isolated from unreacted substrate by a chromatographic separation. In this paper, D-hexosaminate production by oxidative fermentation carried out mainly with Gluconobacter frateurii IFO 3264 is exemplified as a typical example.

Amino sugar phosphate levels in Giardia change during cyst wall formation

The parasite Giardia intestinalis exists as a trophozoite (vegetative) that infects the human small intestine, and a cyst (infective) that is shed in host faeces. Cyst viability in the environment depends upon a protective cyst wall, which consists of proteins and a unique beta(1-3) GalNAc homopolymer. UDP-GalNAc, the precursor for this polysaccharide, is synthesized from glucose by an enzyme pathway that involves amino sugar phosphate intermediates. Using a novel method of microanalysis by capillary electrophoresis, the levels of amino sugar phosphate intermediates in trophozoites before encystment, during a period of active encystment and after the peak of encystment were measured. These levels were used to deduce metabolic control of amino sugar phosphates associated with encystment. Levels of amino sugar phosphate intermediates increased during encystment, and then decreased to nearly non-encysting levels. The most pronounced increase was in glucosamine 6-phosphate, which is the first substrate unique in this pathway, and which is the positive effector for the pathway's putative rate-controlling enzyme, UDP-GlcNAc pyrophosphorylase. Moreover, more UDP-GalNAc than UDP-GlcNAc, its direct precursor, was detected at 24 h. It is postulated that the enhanced UDP-GalNAc is a result of enhanced synthesis of UDP-GlcNAc by the pyrophosphorylase, and its preferential conversion to UDP-GalNAc. These results suggest that kinetics of amino sugar phosphate synthesis in encysting Giardia favours the direction that supports cyst wall synthesis. The enzymes involved in synthesis of UDP-GalNAc and its conversion to cyst wall might be potential targets for therapeutic inhibitors of Giardia infection.

The genes and enzymes for the catabolism of galactitol, D-tagatose, and related carbohydrates in Klebsiella oxytoca M5a1 and other enteric bacteria display convergent evolution

Enteric bacteria (Enteriobacteriaceae) carry on their single chromosome about 4000 genes that all strains have in common (referred to here as "obligatory genes"), and up to 1300 "facultative" genes that vary from strain to strain and from species to species. In closely related species, obligatory and facultative genes are orthologous genes that are found at similar loci. We have analyzed a set of facultative genes involved in the degradation of the carbohydrates galactitol, D-tagatose, D-galactosamine and N-acetyl-galactosamine in various pathogenic and non-pathogenic strains of these bacteria. The four carbohydrates are transported into the cell by phosphotransferase (PTS) uptake systems, and are metabolized by closely related or even identical catabolic enzymes via pathways that share several intermediates. In about 60% of Escherichia coli strains the genes for galactitol degradation map to a gat operon at 46.8 min. In strains of Salmonella enterica, Klebsiella pneumoniae and K. oxytoca, the corresponding gat genes, although orthologous to their E. coli counterparts, are found at 70.7 min, clustered in a regulon together with three tag genes for the degradation of D-tagatose, an isomer of D-fructose. In contrast, in all the E. coli strains tested, this chromosomal site was found to be occupied by an aga/kba gene cluster for the degradation of D-galactosamine and N-acetyl-galactosamine. The aga/kba and the tag genes were paralogous either to the gat cluster or to the fru genes for degradation of D-fructose. Finally, in more then 90% of strains of both Klebsiella species, and in about 5% of the E. coli strains, two operons were found at 46.8 min that comprise paralogous genes for catabolism of the isomers D-arabinitol (genes atl or dal) and ribitol (genes rtl or rbt). In these strains gat genes were invariably absent from this location, and they were totally absent in S. enterica. These results strongly indicate that these various gene clusters and metabolic pathways have been subject to convergent evolution among the Enterobacteriaceae. This apparently involved recent horizontal gene transfer and recombination events, as indicated by major chromosomal rearrangements found in their immediate vicinity.

Lectin-binding sites in newborn human testis

The present investigation has been performed to obtain a complete distributional map of the oligosaccharidic component of the glycoconjugates in the testis of the human newborn. For this purpose seven eight HRP-conjugated lectins (SBA, DBA, PNA, WGA, OOA, UEAI, LTA and ConA) along with enzymatic treatments, were used. The Sertoli cells were characterized by the same sugar residues detected in the testes of adult healthy subject. Beta-N-acetyl-D-galactosamine in the Leydig's cells and a-N- acetyl-D-galactosamine anomer in the spermatogonia seem to be an unique feature of the newborn testis. For this fact SBA and DBA could be considered markers respectively of the Leydig's cells and of the spermatogonia in the newborn testis. Differences in lectin binding, between the newborn and the adult testis as the interstitial tissue and the endothelial cells of the capillary vessels are reported.

Mucin binding mitogenic lectin from freshwater Indian gastropod Belamyia bengalensis: purification and molecular characterization

A lectin was purified from the hemolymph of the freshwater Indian gastropod Belamyia bengalensis. The purification involved successive ion-exchange chromatography on Resource Q and gel filtration on Superose 12 column in FPLC system. Homogeneity of the protein was confirmed by polyacrylamide gel electrophoresis. Belamyia bengalensis lectin (BBL) was a monomeric protein with a molecular weight of 33 kDa as demonstrated by gel filtration and SDS-PAGE. It is a glycoprotein containing 6% total sugar and its activity is highly dependent on Ca(2+). BBL agglutinated human erythrocytes and is a blood group non-specific lectin. It agglutinated animal erythrocytes also. Hapten inhibition studies indicated that BBL shows binding specificity only for N-acetyl-D-glucosamine and N-acetyl-D-galactosamine at a high concentration among the mono- and oligosaccharides tested. Among the glycoproteins used for hemagglutination-inhibition assay, porcine submaxillary mucin was found to be the best inhibitor. Chemical modification studies indicated that Lys, Arg, and Trp are essential for the sugar-binding activity of BBL. Circular dichroism spectra revealed high content of alpha-helical structure in the lectin. BBL is a potent mitogen as it stimulated the T-lymphocyte proliferation, specifically the Th1 subset.

Bilirubin release induced by tumor necrosis factor in combination with galactosamine is toxic to mice

Application of tumor necrosis factor (TNF) in combination with galactosamine (GalN) in mice causes severe apoptosis of hepatocytes, resulting in complete destruction of the liver. Administration of high levels of unconjugated bilirubin and abnormally high production of unconjugated bilirubin have been reported to cause liver damage and are associated with several human pathologies. Serum alanine aminotransferase as well as total and direct bilirubin levels in mice were determined. Bilirubin levels are shown to significantly increase after a challenge with TNF/GalN in mice. Pretreatment with a heme oxygenase-1 inhibitor significantly prevents this release in bilirubin and offers significant protection against TNF/GalN-induced lethality. A correlation between the release of unconjugated bilirubin and the toxicity accompanied with this release is provided.

Small scale rat hepatocyte primary culture with applications for screening hepatoprotective substances

Isolated hepatocytes are known to maintain their physiological functions for over a week when cultured on Matrigel, artificially reconstituted from basement membrane components. Although this culture technique has been frequently used in research on hepatocyte functions, there has been a limitation on its application for small scale experiments due to some technical problems. By using micro-culture plates with 96 round-bottom wells, we succeeded in coating the wells uniformly with Matrigel. When the cultured hepatocytes were treated with either 10 mM, 15 mM, or 20 mM of acetaminophen or 1 mM, 10 mM, or 20 mM of D-galactosamine, the viability of the hepatocytes became 91.1%, 75.3%, 64.7%, and 79.0%, 43.8%, 26.2% of the non-treated control at 48 hours, respectively. Fractionated extracts of Glycyrrhiza glabra L. and Schisandra chinensis Baillon inhibited the action of acetaminophen or D-galactosamine in this model. From these results, we concluded that the microculture system presented here is capable of maintaining the in vivo characteristics of hepatocytes and is suitable for the screening of hepatoprotective substances.

Spherical bodies present within the germinal vesicle of Podarcis sicula previtellogenic oocyte derive from the temporaneous inactivation of ribosomal genes

In the present paper we have investigated the origin of the spherical bodies (SBs) present within the germinal vesicle of about 400 microm previtellogenic oocytes in the lizard Podarcis sicula. In particular, we have attempted to clarify whether they derive from the single, large nucleolus present in early diplotenic oocyte as a consequence of ribosomal gene inactivation. We have, therefore, experimentally induced a decrease in rRNA synthesis by injecting animals with D-galactosamine or by exposing them to low temperatures. The investigations carried out have demonstrated that both treatments induce significant ultrastructural changes in the nucleolar apparatus and in particular fragmentation and the formation of SBs comparable to those observed in germinal vesicle under physiological conditions. These results indicate that the germinal vesicle of Podarcis sicula has a nucleolar apparatus that significantly changes its aspect according to its functional status and reveal that in this species, the time course of rRNA synthesis is peculiar with respect to any other vertebrate oocyte studies so far.

Primary cultures of human hepatocytes as a tool in cytotoxicity studies: cell protection against model toxins by flavonolignans obtained from Silybum marianum

The aim of this study was to evaluate the cytoprotective effects upon primary human hepatocytes of silymarin extract and its main flavonolignans following exposure to the cytotoxic actions of model toxins. The conditions for the hepatocyte intoxication were optimised for allyl alcohol, carbon tetrachloride, D-galactosamine and paracetamol. Silymarin extract, silychristin and silydianin did not exert cytotoxicity (10-100 microM), whereas silybin and isosilybin at higher concentrations and after longer incubation periods were cytotoxic. All main flavonolignans of silymarin tested displayed concentration-dependent cytoprotection against the toxic effects of both allyl alcohol and carbon tetrachloride but neither paracetamol nor galactosamine. The best protection was achieved by silydianin and silychristin and to a lesser degree by silymarin, while silybin and isosilybin were less effective. It is concluded that these differing outcomes result from the varying abilities of the Silybum marianum substances tested to stabilize the cell membrane, exert antioxidant properties and exhibit intrinsic toxicity.

Capillary electrophoresis separation of autocondensation glycation products of glucosamine

Glucosamine nonenzymatically forms autocondensation glycation products under physiological conditions. Many studies have reported the effectiveness of oral doses of glucosamine alone or in combination with the galactosamine containing chondroitin in treating osteoarthritis. However, none of these studies has considered whether it is the glucosamine itself and/or one or more of its autocondensation products that exert this effect. A capillary electrophoresis method was developed to monitor the nonenzymatic formation of autocondensation glycation products of glucosamine, galactosamine, and mannosamine under physiological conditions. Major components were detected and separated by CE with a UV detector. The effects of concentration and incubation time on product species were determined. The method described is simple, rapid, and effective.

Metabolic profiling of the effects of D-galactosamine in liver spheroids using (1)H NMR and MAS-NMR spectroscopy

We report here the combined application of (1)H magic angle spinning (MAS) and high-resolution NMR spectroscopy and pattern recognition methods to study the effects of a model toxin (D-galactosamine) in liver spheroid cultures. (1)H NMR spectra of metabolic profiles of spheroids showed closer similarities to intact liver spectra than those of isolated hepatocytes, suggesting their superiority as an in vitro model system. Batches of spheroids were prepared from male Sprague Dawley rat livers and incubated in control hepatocyte medium or medium containing D-galactosamine (4 or 20 mM) for 4 or 24 h. Intact spheroids were packed into rotors and analyzed using MAS-NMR spectroscopy or homogenized and analyzed using conventional (1)H NMR spectroscopy. Principal components analysis, (PCA), of the NMR data revealed separation of control and D-galactosamine-treated spheroids based on changes in the concentrations of the triglycerides and elevations in cholesterol and esters. The absence of cholesterol in hepatocytes and the relative under-representation of the lipid resonances offer an important advantage of spheroids over hepatocytes for the (1)H NMR studies of fatty liver. Orthogonal signal correction (OSC) was used as a data filter to remove non-dose-dependent variation from the NMR spectra, improving the classification of treated spheroids and controls. This work shows that useful metabolic information can be obtained on drug toxicity by the use of combined MAS-NMR and high-resolution NMR of liver spheroids and that such studies may enhance the validation of in vitro techniques against in vivo models for metabolic profiling.

Biosynthesis of tunicamycin and metabolic origin of the 11-carbon dialdose sugar, tunicamine

Tunicamycin is a reversible inhibitor of polyprenol-phosphate: N-acetylhexosamine-1-phosphate translocases and is produced by several Streptomyces species. We have examined tunicamycin biosynthesis, an important but poorly characterized biosynthetic pathway. Biosynthetic precursors have been identified by incorporating radioactive and stable isotopes, and by determining the labeling pattern using electrospray ionization-collision induced dissociation-mass spectrometry (ESI-CID-MS), and proton, deuterium, and C-13 nuclear magnetic resonance (NMR) spectroscopy. Preparation and analysis of [uracil-5-(2)H]-labeled tunicamycin established the complete ESI-CID-MS fragmentation pathway for the major components of the tunicamycin complex. Competitive metabolic experiments indicate that 7 deuteriums incorporate into tunicamycin from [6,6'-(2)H,(2)H]-labeled D-glucose, 6 of which arise from D-GlcNAc and 1 from uridine and/or D-ribose. Inverse correlation NMR experiments (heteronuclear single-quantum coherence (HSQC)) of (13)C-labeled tunicamycin enriched from D-[1-(13)C]glucose suggest that the unique tunicamine 11-carbon dialdose sugar backbone arises from a 5-carbon furanose precursor derived from uridine and a 6-carbon N-acetylamino-pyranose precursor derived from UDP-D-N-acetylglucosamine. The equivalent incorporation of (13)C into both the alpha-1" and beta-11' anomeric carbons of tunicamycin supports a direct biosynthesis via 6-carbon metabolism. It also indicates that the tunicamine motif and the alpha-1"-linked GlcNAc residue are both derived from the same metabolic pool of UDP-GlcNAc, without significant differential metabolic processing. A biosynthetic pathway is therefore proposed for tunicamycin for the first time: an initial formation of the 11-carbon tunicamine sugar motif from uridine and UDP-GlcNAc via uridine-5'-aldehyde and UDP-4-keto-6-ene-N-acetylhexosamine, respectively, and subsequent formation of the anomeric-to-anomeric alpha, beta-1",11'-glycosidic bond.

Bacterial peptidoglycan-associated lipoprotein is released into the bloodstream in gram-negative sepsis and causes inflammation and death in mice

Gram-negative bacterial sepsis commonly causes organ dysfunction and death in humans. Although circulating bacterial toxins trigger inflammation in sepsis, little is known about the composition of bacterial products released into the blood during sepsis or the contribution of various bacterial components to the pathogenesis of sepsis. We have shown that diverse Gram-negative bacteria release bacterial peptidoglycan-associated lipoprotein (PAL) into serum. The present studies explored release of PAL into the blood during sepsis and tested the hypothesis that PAL contributes to bacterial virulence and inflammation in Gram-negative sepsis. Released PAL was detected in the blood of 94% of mice following cecal ligation and puncture. Picomolar to nanomolar levels of PAL stimulated macrophages and splenocytes from lipopolysaccharide-hyporesponsive (C3H/HeJ) mice. Injection of PAL into C3H/HeJ mice stimulated production of serum cytokines and increased pulmonary and myocardial expression of inflammatory markers. PAL caused death in sensitized C3H/HeJ mice. Mutant Escherichia coli bacteria with reduced levels of PAL or truncated PAL were less virulent than wild-type bacteria, as indicated by higher survival rates and lower circulating levels of interleukin 6 and bacteria in a model of peritonitis in lipopolysaccharide-responsive mice. The studies suggest that PAL may be an important bacterial mediator of Gram-negative sepsis.

Several polylactosamine-modifying glycosyltransferases also use internal GalNAcbeta1-4GlcNAc units of synthetic saccharides as acceptors

The GalNAcbeta1-4GlcNAc determinant (LdN) occurs in some human and bovine glycoconjugates and also in lower vertebrates and invertebrates. It has been found in unsubstituted as well as terminally substituted forms at the distal end of conjugated glycans, but it has not been reported previously at truly internal positions of polylactosamine chains. Here, we describe enzyme-assisted conversion of LdNbeta1-OR oligosaccharides into GlcNAcbeta1-3GalNAcbeta1-4GlcNAcbeta1-OR. The extension reactions, catalyzed by human serum, were modeled after analogous beta3-GlcNAc transfer processes that generate GlcNAcbeta1-3Galbeta1-4GlcNAcbeta1-OR. The newly synthesized GlcNAcbeta1-3GalNAc linkages were unambiguously identified by nuclear magnetic resonance data, including the appropriate long-range correlations in heteronuclear multiple bond correlation spectra. The novel GlcNAcbeta1-3'LdN determinant proved to be a functional acceptor for several mammalian glycosyltransferases, suggesting that human polylactosamines may contain internal LdN units in many distinct forms. The GlcNAcbeta1-3'LdN determinant was unusually resistant toward jackbean beta-N-acetylhexosaminidase; the slow degradation should lead to a convenient method for the search of putative internal LdN determinants in natural polylactosamine chains.

The role of progenitor cells in repair of liver injury and in liver transplantation

There are three levels of cells in the hepatic lineage that respond to injury or carcinogenesis: the mature hepatocyte, the ductular "bipolar" progenitor cell, and a putative periductular stem cell. Hepatocytes are numerous, and respond rapidly to liver cell loss by one or two cell cycles but can only produce other hepatocytes. The ductular progenitor cells are less numerous, may proliferate for more cycles than hepatocytes, and are generally considered "bipolar," i.e., they can give rise to biliary cells or hepatocytes. Periductular stem cells are rare in the liver, have a very long proliferation potential, and may be multipotent. Extrahepatic (bone marrow) origin of the periductular stem cells is supported by recent data showing that hepatocytes may express genetic markers of donor hematopoietic cells after bone marrow transplantation. These different regenerative cells with variations in potential for proliferation and differentiation may provide different sources of cells for liver transplantation: hepatocytes for treatment of acute liver damage, liver progenitor cell lines for liver-directed gene therapy, and bone marrow-derived cells for chronic long-term liver replacement. A limiting factor in the success of liver cell transplantation is the condition of the hepatic microenvironment in which the cells must proliferate and set up housekeeping.