AR-12 Has a Bactericidal Activity and a Synergistic Effect with Gentamicin against Group A Streptococcus

Streptococcus pyogenes (group A Streptococcus (GAS) is an important human pathogen that can cause severe invasive infection, such as necrotizing fasciitis and streptococcal toxic shock syndrome. The mortality rate of streptococcal toxic shock syndrome ranges from 20% to 50% in spite of antibiotics administration. AR-12, a pyrazole derivative, has been reported to inhibit the infection of viruses, intracellular bacteria, and fungi. In this report, we evaluated the bactericidal activities and mechanisms of AR-12 on GAS infection. Our in vitro results showed that AR-12 dose-dependently reduced the GAS growth, and 2.5 μg/mL of AR-12 significantly killed GAS within 2 h. AR-12 caused a remarkable reduction in nucleic acid and protein content of GAS. The expression of heat shock protein DnaK and streptococcal exotoxins was also inhibited by AR-12. Surveys of the GAS architecture by scanning electron microscopy revealed that AR-12-treated GAS displayed incomplete septa and micro-spherical structures protruding out of cell walls. Moreover, the combination of AR-12 and gentamicin had a synergistic antibacterial activity against GAS replication for both in vitro and in vivo infection. Taken together, these novel findings obtained in this study may provide a new therapeutic strategy for invasive GAS infection.

IL-33/ST2 Axis Plays a Protective Effect in Streptococcus pyogenes Infection through Strengthening of the Innate Immunity

Group A Streptococcus (GAS) causes invasive human diseases with the cytokine storm. Interleukin-33 (IL-33)/suppression of tumorigenicity 2 (ST2) axis is known to drive TH2 response, while its effect on GAS infection is unclear. We used an air pouch model to examine the effect of the IL-33/ST2 axis on GAS-induced necrotizing fasciitis. GAS infection induced IL-33 expression in wild-type (WT) C57BL/6 mice, whereas the IL-33- and ST2-knockout mice had higher mortality rates, more severe skin lesions and higher bacterial loads in the air pouches than those of WT mice after infection. Surveys of infiltrating cells in the air pouch of GAS-infected mice at the early stage found that the number and cell viability of infiltrating cells in both gene knockout mice were lower than those of WT mice. The predominant effector cells in GAS-infected air pouches were neutrophils. Absence of the IL-33/ST2 axis enhanced the expression of inflammatory cytokines, but not TH1 or TH2 cytokines, in the air pouch after infection. Using in vitro assays, we found that the IL-33/ST2 axis not only enhanced neutrophil migration but also strengthened the bactericidal activity of both sera and neutrophils. These results suggest that the IL-33/ST2 axis provided the protective effect on GAS infection through enhancing the innate immunity.

Autophagy Drives Galectin-1 Secretion From Tumor-Associated Macrophages Facilitating Hepatocellular Carcinoma Progression

Galectin-1 (Gal-1) is a secretory lectin with pro-tumor activities and is associated strongly with hepatocellular carcinoma (HCC) development. Although Gal-1 is a well-known soluble pro-tumor factor in the tumor microenvironment (TME), the secretion mode of Gal-1 is not clearly defined. On the other hand, in addition to cancer cells, Gal-1 is widely expressed in tumor stromal cells, including tumor-associated macrophages (TAMs). TAMs are a significant component of stromal cells in TME; however, their contributions in producing Gal-1 to TME are still not explored. Here we reveal that TAMs can actively secrete Gal-1 in response to stimuli of HCC cells. Gal-1 produced by TAMs leads to an increase of the systemic level of Gal-1 and HCC tumor growth in mice. Mechanistically, TLR2-dependent secretory autophagy is found to be responsible for Gal-1 secretion from TAMs. Gal-1 acts as a cargo of autophagosomes to fuse with multivesicular bodies via Rab11 and VAMP7-mediated vesicle trafficking before being secreted. This autophagy-regulated Gal-1 secretion in TAMs correlates to poor overall survival and progression-free survival rates of HCC patients. Our findings uncover the secretion mode of Gal-1 via secretory autophagy and highlight the pathological role of TAM-produced Gal-1 in HCC progression.

Autophagy drives plasticity and functional polarization of tumor-associated macrophages

Tumor-associated macrophages (TAMs) are a major component of the tumor microenvironment (TME) and are key cells in regulating tumor development, metastasis, immune responses, inflammation, and chemoresistance. In response to TME stimulation, circulating monocytes are recruited and differentiated as TAMs. Most TAMs are defined as alternatively activated (M2) phenotype to create immunosuppressive TME and support tumor progression. In contrast, classically activated (M1) TAMs can produce pro-inflammatory cytokines and enhance immune responses against tumor development. Autophagy is a conserved catabolic process to control cellular homeostasis and biological function. Emerging evidence reveals crucial contribution of autophagy in modulating TAM plasticity and functional polarization in TME. In this review, we introduce the current understanding of autophagy-regulated TAM function in development of cancer. We focus on how autophagy modulates antigen presentation, LC3-associated phagocytosis, cytokine secretion, inflammasome regulation, recruitment, differentiation, and polarization of TAMs and suggest strategies for potential therapeutics by targeting autophagy in TAMs. We expect this review can provide a new notion of future cancer immunotherapy.

Immunization with a streptococcal multiple-epitope recombinant protein protects mice against invasive group A streptococcal infection

Streptococcus pyogenes (group A Streptococcus; GAS) causes clinical diseases, including pharyngitis, scarlet fever, impetigo, necrotizing fasciitis and streptococcal toxic shock syndrome. A number of group A streptococcus vaccine candidates have been developed, but only one 26-valent recombinant M protein vaccine has entered clinical trials. Differing from the design of a 26-valent recombinant M protein vaccine, we provide here a vaccination using the polyvalence epitope recombinant FSBM protein (rFSBM), which contains four different epitopes, including the fibronectin-binding repeats domain of streptococcal fibronectin binding protein Sfb1, the C-terminal immunogenic segment of streptolysin S, the C3-binding motif of streptococcal pyrogenic exotoxin B, and the C-terminal conserved segment of M protein. Vaccination with the rFSBM protein successfully prevented mortality and skin lesions caused by several emm strains of GAS infection. Anti-FSBM antibodies collected from the rFSBM-immunized mice were able to opsonize at least six emm strains and can neutralize the hemolytic activity of streptolysin S. Furthermore, the internalization of GAS into nonphagocytic cells is also reduced by anti-FSBM serum. These findings suggest that rFSBM can be applied as a vaccine candidate to prevent different emm strains of GAS infection.

Application of the C3-binding motif of streptococcal pyrogenic exotoxin B to protect mice from invasive group a streptococcal infection

Group A streptococcus (GAS) is an important human pathogen that produces several extracellular exotoxins to facilitate invasion and infection. Streptococcal pyrogenic exotoxin B (SPE B) has been demonstrated to be an important virulence factor of GAS. Our previous studies indicate that SPE B cleaves complement 3 (C3) and inhibits the activation of complement pathways. In this study, we constructed and expressed recombinant fragments of SPE B to examine the C3-binding site of SPE B. Using enzyme-linked immunosorbent assays and pull-down assays, we found that the C-terminal domain, containing amino-acid residues 345–398, of SPE B was the major binding site of human serum C3. We further identified a major, Ala³⁷⁶-Pro³⁹⁸, and a minor C3-binding motif, Gly³⁴⁶-Gly³⁶⁰, that both mediated the binding of C3 complement. Immunization with the C3-binding motifs protected mice against challenge with a lethal dose of non-invasive M49 strain GAS but not invasive M1 strains. To achieve higher efficiency against invasive M1 GAS infection, a combination of synthetic peptides derived from C-terminal epitope of streptolysin S (SLSpp) and from the major C3-binding motif of SPE B (PP6, Ala³⁷⁶-Pro³⁹⁸) was used to elicit specific immune response to those two important streptococcal exotoxins. Death rates and the severity of skin lesions decreased significantly in PP6/SLSpp-immunized mice that were infected with invasive M1 strains of GAS. These results indicate a combination of the C3-binding motif of SPE B and the protective epitope of SLS could be used as a subunit vaccine against invasive M1 strains group A streptococcal infection.

Determining antibody-binding site of streptococcal pyrogenic exotoxin B to protect mice from group a streptococcus infection

Streptococcal pyrogenic exotoxin B (SPE B), a cysteine protease, is an important virulence factor in group A streptococcal (GAS) infection. SPE B binds and cleaves antibody isotypes and further impairs the immune system by inhibiting complement activation. In this study, we examined the antibody-binding site of SPE B and used it to block SPE B actions during GAS infection. We constructed different segments of the spe B gene and induced them to express different recombinant fragments of SPE B. Using an enzyme-linked immunosorbent assay (ELISA), we found that residues 345–398 of the C-terminal domain of SPE B (rSPE B_345–398), but not the N-terminal domain, was the major binding site for antibody isotypes. Using a competitive ELISA, we also found that rSPE B_345–398 bound to the Fc portion of IgG. The in vitro functional assays indicate that rSPE B_345–398 not only interfered with cleavage of antibody isotypes but also interfered with SPE B-induced inhibition of complement activation. Immunization of BALB/c mice using rSPE B_345–398 was able to induce production of a high titer of anti-rSPE B_345–398 antibodies and efficiently protected mice from GAS-induced death. These findings suggest that SPE B uses its C-terminal domain to bind the Fc portion of IgG and that immunization of mice with this binding domain (rSPE B_345–398) could protect mice from GAS infection.

Inhibition of group A streptococcal infection by Melaleuca alternifolia (tea tree) oil concentrate in the murine model

AIMS

To investigate the effect of a water-soluble Melaleuca alternifolia concentrate (MAC) on group A streptococcus (GAS; Streptococcus pyogenes)-induced necrotizing fasciitis.

METHODS AND RESULTS

MAC pretreatment (1% and 2% v/v) was able to protect mice from GAS infection in an air pouch model. GAS-induced mouse death and skin injury were inhibited dose dependently by MAC. Administration of MAC at 6 h post-GAS infection partially delayed mouse death. Surveys of the exudates of the air pouch of MAC-treated mice revealed that the survival of infiltrating cells was prolonged, the bacteria were eliminated, and the production of inflammatory cytokines was inhibited. MAC could directly inhibit the growth of GAS in vitro, and the minimal inhibitory concentration (MIC) of MAC for GAS was determined as 0.05% v/v using the time-kill assay. Furthermore, a sub-MIC dose of MAC not only enhanced the bactericidal activity of RAW264.7 macrophage cells against GAS but also increased susceptibility of GAS for blood clearance.

CONCLUSIONS

These results suggest that MAC may inhibit GAS-induced skin damage and mouse death by directly inhibiting GAS growth and enhancing the bactericidal activity of macrophages.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results provide scientific data on the use of MAC for the treatment of GAS-induced necrotizing fasciitis in the murine model.

Concanavalin A protects mice from a lethal inoculation of intragastric Klebsiella pneumoniae and reduces the induced liver damage

Intragastric inoculation of Klebsiella pneumoniae can cause invasive diseases, including necrosis of liver tissues and bacteremia. The effect of concanavalin A (ConA) on K. pneumoniae was tested. Pretreatment with ConA was able to protect mice from K. pneumoniae infection in an intragastric model. K. pneumoniae-induced mouse death and liver injury such as liver necrosis, as well as blood levels of aspartate aminotransferase and alanine aminotransferase, were inhibited in a dose-dependent manner by ConA. ConA administered intravenously as late as 24 h after K. pneumoniae inoculation was still protective. In an in vitro assay, ConA was able to bind K. pneumoniae cells directly and further agglutinate them but had no effect on their in vitro growth. Surveys of bacterial counts of ConA-treated mice revealed that the bacteria were eliminated effectively in both blood and liver tissues. Furthermore, the bactericidal activity of macrophages against K. pneumoniae was also enhanced in a dose-dependent manner by ConA in an in vitro culture. These data suggest that ConA is a potentially therapeutic agent for K. pneumoniae-induced liver infection.

Streptococcal pyrogenic exotoxin B cleaves properdin and inhibits complement-mediated opsonophagocytosis

Streptococcal pyrogenic exotoxin B (SPE B), a cysteine protease, is an important virulence factor in group A streptococcal (GAS) infection. The reduction of phagocytic activity by SPE B may help prevent bacteria from being ingested. In this study, we investigated the mechanism SPE B uses to enable bacteria to resist opsonophagocytosis. Using Western blotting and an affinity column immobilized with SPE B, we found that both SPE B and C192S, an SPE B mutant lacking protease activity, bound to serum properdin, and that SPE B, but not C192S, degraded serum properdin. Further study showed that SPE B-treated, but not C192S-treated, serum blocked the alternative complement pathway. Reconstitution of properdin into SPE B-treated serum unblocked the alternative pathway. GAS opsonized with SPE B-treated serum was more resistant to neutrophil killing than GAS opsonized with C192S-treated or normal serum. These results suggest that a novel SPE B mechanism, one which degrades serum properdin, enables GAS to resist opsonophagocytosis.

Intracellular alkalinization in dexamethasone-induced thymocyte apoptosis

Glucocorticoid can induce apoptosis of thymocytes, but its mechanism is not clear yet. In this study, we reported that dexamethasone-induced apoptosis was associated with intracellular alkalinization. Dexamethasone induced a higher percentage of apoptosis in 138 mM than in 50 mM NaCl, total abrogation of apoptosis was noted in NaCl-depleted culture medium. Highest apoptotic rate was observed in medium with pH 7.2, whereas it was partially and completely inhibited at pH 6.5 and pH 6.0, respectively. Intracellular pH was higher in pre-apoptotic thymocytes than non-apoptotic ones. The Na+/H+ antiporter inhibitor of 5-(N,N'-dimethyl)-amiloride inhibited the dexamethasone-induced increase in pHi and apoptosis of thymocytes. Glucocorticoid antagonist RU486 also blocked the dexamethasone-induced effect. Furthermore, the apoptosis and increase in intracellular pH induced by dexamethasone were inhibited by cycloheximide, actinomycin D. It seems that intracellular pH is increased during the development of thymocyte apoptosis and inhibiting its increment would retard the rate of progression to cell death.

In vitro action of carboxyfullerene

Fullerene compounds have avid reactivity with free radicals and are regarded as 'radical sponges'. The trimalonic acid derivative of fullerene is one of the water-soluble compounds that has been synthesized and found to be an effective antioxidant both in vivo and in vitro. Carboxyfullerene has been shown to be effective in the treatment of both Gram-positive and -negative infections, although its mode of action is poorly understood. We determined the MIC and minimal bactericidal concentration of carboxyfullerene for 20 isolates, including Staphylococcus spp., Streptococcus spp., Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Klebsiella pneumoniae. We further investigated the action of carboxyfullerene using transmission electron microscopy (TEM), anticarboxyfullerene antibody binding assay and a membrane perturbation assay. All Gram-positive species were inhibited by < or = 50 mg/L of carboxyfullerene, whereas Gram-negative species were not inhibited, even at 500 mg/L carboxyfullerene. Bactericidal activity was demonstrated only for Gram-positive species, particularly for Streptococcus pyogenes A-20, which was killed rapidly. Intercalation of carboxyfullerene into the cell wall of staphylococci and streptococci was demonstrated by TEM and anti-carboxyfullerene binding assay. Damage to the cell membrane in Gram-positive, but not Gram-negative, bacteria was confirmed by the membrane perturbation assay. These findings indicate that the action of carboxyfullerene on Gram-positive bacteria is achieved by insertion into the cell wall and destruction of membrane integrity.

Development of hematogenous pneumococcal meningitis in adult mice: the role of TNF-alpha

Bacterial penetration across the blood-brain barrier (BBB) into the central nervous system is the first step in development of meningitis. The role of tumor necrosis factor-alpha (TNF-alpha) in the penetration process was examined with peripheral infection of Streptococcus pneumoniae type 6. After intraperitoneal infection of S. pneumoniae type 6, the BBB opening was increased continuously from 6 h and the mice died of septic shock within 36 h due to bacterial overgrowth. The bacteria crossed the BBB and began to deposit in brain at 6 h post infection. There was strong staining of TNF-alpha on blood vessels of brain from 6 h to 24 h post infection. Anti-TNF-alpha antibody blocked both the BBB opening and the entrance of circulatory S. pneumoniae type 6 into brain, indicating that TNF-alpha played an important role in controlling the opening of BBB. Furthermore, an adult murine model of hematogenous pneumococcal meningitis was developed that is based on opening of the BBB by TNF-alpha and controlling the degree of bacteremia by cefazolin antibiotic. In conclusion, hematogenous meningitis developed as TNF-alpha initiated BBB opening, peripheral bacteria entered into the brain and formed bacterial emboli, and then progressed to meningitis.

Inhibition of group A streptococcus infection by carboxyfullerene

The effect of a water-soluble trimalonic acid derivative of fullerene, carboxyfullerene, against Streptococcus pyogenes infection was tested. Pretreatment with carboxyfullerene was able to protect mice from S. pyogenes infection in an air pouch model. S. pyogenes-induced death and skin injury were inhibited dose dependently by carboxyfullerene. Administration of carboxyfullerene via the peritoneum and air pouch at 3 h post-S. pyogenes infection was able to protect 33% of mice from death. Surveys of exudates of the air pouch of carboxyfullerene-treated mice revealed that survival of infiltrating neutrophils was prolonged and that the bacteria were eliminated as a result of enhanced bactericidal activity of the neutrophils. Furthermore, carboxyfullerene was able to directly inhibit in vitro growth of S. pyogenes. These data suggest that carboxyfullerene can be considered an antimicrobial agent for group A streptococcus infection.

Tumour necrosis factor-alpha causes an increase in blood-brain barrier permeability during sepsis

Blood-brain barrier (BBB) permeability during sepsis with Escherichia coli or Streptococcus pneumoniae was examined in a mouse model and measured by a circulating beta-galactosidase tracer. The leakage of brain microvascular vessels during sepsis was confirmed by transmission electron microscopic examination of brain tissues stained with horseradish peroxidase. The increase of BBB permeability induced by E. coli and S. pneumoniae, which was maximal at 3 h and 12 h after injection, respectively, was transient because of rapid clearance of the bacteria from the blood. Tumour necrosis factor-alpha (TNF-alpha) was stained on microvascular vessels of the brain during sepsis and intravenous injection of recombinant TNF-alpha also increased the BBB permeability. The increase in BBB permeability induced by either E. coli or S. pneumoniae could be inhibited by anti-TNF-alpha antibody. It was concluded that circulating TNF-alpha generated during sepsis induced the increase in BBB permeability.

The genomic structure of SYCP3, a meiosis-specific gene encoding a protein of the chromosome core

SYCP3 localizes to the lateral elements of the synaptonemal complex and is essential for male meiosis. The genomic structure of SYCP3 consists of nine exons spanning approximately 14 kb. In mouse and rat, but not in hamster, the putative translation start of SYCP3 is present in the first exon. The putative promoter of SYCP3 was also cloned and shown to drive transcription of a reporter gene in somatic cells.

Glycine metabolism in Candida albicans: characterization of the serine hydroxymethyltransferase (SHM1, SHM2) and threonine aldolase (GLY1) genes

Genes encoding the mitochondrial (SHM1) and cytosolic (SHM2) serine hydroxymethyltransferases, and the L-threonine aldolase gene (GLY1) from Candida albicans were cloned and sequenced. All three genes are involved in glycine metabolism. The C. albicans Shm1 protein is 82% identical to that from Saccharomyces cerevisiae and 56% identical to that from Homo sapiens. The corresponding identities for the Shm2 proteins are 68% and 53%. The Gly1 protein shares significant identity with the S. cerevisiae L-threonine aldolase (55%) and also with threonine aldolases from Aeromonas jandiae (36%) and Escherichia coli (36%). Genetic ablation experiments show that GLY1 is a non-essential gene in C. albicans and that L-threonine aldolase plays a lesser role in glycine metabolism than it does in S. cerevisiae. GenBank Accession Nos of the C. albicans SHM1 and SHM2 are AF009965 and AF009966, respectively. Accession No. for C. albicans GLY1 is AF009967.

Toward real-world sequencing by microdevice electrophoresis

We report results using a microdevice for DNA sequencing using samples from chromosome 17, obtained from the Whitehead Institute Center for Genome Research (WICGR) production line. The device had an effective separation distance of 11.5 cm and a lithographically defined injection width of 150 microm. The four-color raw data were processed, base-called by the sequencing software Trout, and compared to the corresponding ABI 377 sequence from WICGR. With a criteria of 99% accuracy, we achieved average continuous reads of 505 bases in 27 min with 3% linear polyacrylamide (LPA) at 150 V/cm, and 460 bases in 22 min with 4% LPA at 200 V/cm at a temperature of 45 degrees C. In the best case, up to 565 bases could be base-called with the same accuracy in <25 min. In some instances, Trout allowed for accurate base-calling down to a resolution R as low as R = 0.35. This may be due in part to the high signal-to-noise ratio of the microdevice. Unlike many results reported on capillary machines, no additional sample cleanup other than ethanol precipitation was required. In addition, DNA fragment biasing (i.e., discrimination against larger fragments) was reduced significantly through the unique sample injection mechanism of the microfabricated device. This led to increased signal strength for long fragments, which is of great importance for the high performance of the microdevice.

Inhibition of Escherichia coli-induced meningitis by carboxyfullerence

The effect of a water-soluble malonic acid derivative of carboxyfullerence (C60) against Escherichia coli-induced meningitis was tested. C60 can protect the mice from E. coli-induced death in a dose-dependent manner. C60 administered intraperitoneally as late as 9 h after E. coli injection was still protective. The C60-treated mice had less tumor necrosis factor alpha and interleukin-1beta production by staining of brain tissue compared to the levels of production for nontreated mice. The E. coli-induced increases in blood-brain barrier permeability and inflammatory neutrophilic infiltration were also inhibited. These data suggest that C60 is a potentially therapeutic agent for bacterial meningitis.

TNFalpha-induced cyclooxygenase 2 not only increases the vasopermeability of blood-brain barrier but also enhances the neutrophil survival in Escherichia coli-induced brain inflammation

In Escherichia coli-induced brain inflammation, cyclooxygenase-2 was induced not only on brain arterioles at 3 h, but also on infiltrating neutrophils at 9 h post-intracerebral injection. Intravenous injection of E. coli or recombinant TNFalpha also induced cyclooxygenase-2 expression on arterioles. Cyclooxygenase-2 and TNFalpha were co-localized on the arterioles as well as the infiltrating neutrophils by serial-section staining, indicating that cyclooxygenase-2 was induced by TNFalpha. NS398 (a cyclooxygenase-2 selective inhibitor) not only inhibited the increase of blood-brain barrier permeability, but also enhanced the apoptosis of the infiltrating neutrophils after E. coli stimulation. This suggests that TNFalpha-stimulated cyclooxygenase-2 induction play an important role on E. coli-induced brain inflammation. Its inhibition would help the resolution of neutrophil-mediated brain inflammation.

Protein coding gene trees in ciliates: comparison with rRNA-based phylogenies

We have reexamined the phylogeny of the ciliates using alpha-tubulin and phosphoglycerate kinase gene sequences. For alpha-tubulin, we have compared the amino acid and nucleotide sequences of 20 species representing seven of the nine classes of the phylum (Karyorelictea, Heterotrichea, Hypotrichea, Oligohymenophorea, Colpodea, Nassophorea, and Litostomatea). The phylogenetic tree resembles a bush from which three monophyletic lineages can be distinguished which correspond to the three classes Hypotrichea, Oligohymenophorea, and Litostomatea. For phosphoglycerate kinase, we have compared the amino acid sequences from 7 species representing three classes (Heterotrichea, Hypotrichea, and Oligohymenophorea). The branching pattern is resolved in three deeply separated branches with an early emergence of the heterotrich. Our comparative analysis shows that if alpha-tubulin phylogeny is not informative at the interclass level, the preliminary data from the phosphoglycerate kinase molecule appear more promising. Nevertheless, at low taxonomic level and at the class level, the resolved phylogenetic relationships inferred from both protein and rRNA sequence data are congruent.

Increase of intracellular pH in p53-dependent apoptosis of thymocytes induced by gamma radiation

Irradiation with gamma rays induces apoptosis of thymocytes by a p53-dependent pathway, but its mechanism is not clear. In this study, we report that gamma-ray-induced apoptosis was associated with the intracellular alkalinization of the thymocytes. After exposure to gamma rays, thymocytes underwent apoptosis when cultured in vitro, and the degree of apoptosis was dependent on the incubation period: The longer the incubation period, the greater the number of cells undergoing apoptosis. However, this apoptosis could be inhibited by the acidic condition of the culture. There was a positive correlation between the pHi of thymocytes and the degree of apoptosis. Treatment with gamma radiation induced apoptosis as well as the elevation of the pHi in thymocytes. The intracellular pH was higher in pre-apoptotic thymocytes than in those that did not undergo apoptosis. Furthermore, apoptosis induced by gamma radiation was inhibited by cycloheximide, actinomycin D or the intracellular Ca2+ chelator, TMB-8. The p53 protein is induced after gamma irradiation. Thus it appears that intracellular pH is increased during the gamma-ray-induced p53-dependent apoptosis of thymocytes.

Infiltrated Cells in Experimental Allergic Encephalomyelitis by Additional Intracerebral Injection in Myelin-Basic-Protein-SensitizedB6 Mice

We previously reported that murine experimental allergic encephalomyelitis can be induced by an additional intraperitoneal and intracerebral (i.c.) restimulation in resistant B6 mice after standard immunization with myelin antigens in complete Freund's adjuvant and Bordetella pertussis coadjuvant. Neutrophils infiltrated into perivascular spaces at 12 h, followed by mononuclear cells 24 h after i.c. injection. In this study, we report that the i.c. injection induced the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). The kinetic expression of ICAM-1 or VCAM-1 on brain endothelial cells paralleled the infiltration of neutrophils and mononuclear cells, respectively. The infiltrated lymphocytes also expressed very late antigen-4 (VLA-4) molecules. The microvascular endothelial cells were positive for VCAM-1, whereas the surrounding mononuclear cells were VLA-4 positive. Furthermore, we found a unique subpopulation of cells with characteristics of CD4(-)CD8(-)V(beta)8(+) markers. The kinetic studies of this population showed that these cells were transiently depleted from 12 to 24 h after i.c. challenge (before the development of clinical symptoms) in cervical lymph nodes. These CD4(-)CD8(-)V(beta)8(+) cells can be expanded by in vitro culture with myelin basic protein or IL-2. No significant changes of CD4(+)/CD8(+) cells were noted. CD4(+)CD8(-)CD3(+) cells were also found in brain by double histochemical stains and were the major infiltrating cells at 24 or 48 h after i.c. challenge.

Activation of the Na(+)/H(+) antiporter, Na+/HCO3(-)/CO3(2-) cotransporter, or Cl(-)/HCO3(-) exchanger in spontaneous thymocyte apoptosis

This study was undertaken to define the role of ion transporters on the apoptosis of thymocytes. Culture conditions, such as the ionic strength of NaCl, Ca2+, the buffer system (HCO3-/CO2), and the pH, could influence the spontaneous apoptosis of thymocytes. Depletion of NaCl in the culture medium either delayed or completely inhibited the apoptotic process of thymocytes, while its restoration led to a dose-dependent apoptosis. A high concentration (100 microM) of Ca2+ induced thymocyte apoptosis in the nominal absence of NaCl, whereas a low concentration (10 microM) enhanced apoptosis in the presence of 138 mM NaCl. Thymocytes had a higher spontaneous apoptotic rate in cultures without HCO3-/CO2 than in those with HCO3-/CO2. The thymocyte apoptosis completely ceased in medium at pH 6.0 and was considerably enhanced at pH 7.6. Intracellular pH, determined with the pH-sensitive bis-carboxyethyl carboxyfluorescein probe, was higher in apoptotic thymocytes than in nonapoptotic cells. Spontaneous apoptosis occurred in cells with alkaline intracellular condition, whereas it was considerably retarded in cells under acidified conditions. Amiloride analogue, including 5-(N,N-dimethyl)-amiloride (Na+/H+ antiporter), 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (Cl-/HCO3- exchanger), and 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonic acid (Na+/HCO3-/CO3(2-) cotransporter), inhibited the spontaneous thymocyte apoptosis. In contrast, neither cycloheximide nor actinomycin D had the same effect. In addition, thymocyte apoptosis was enhanced by PMA, but inhibited by forskolin. Taken together, thymocytes cultured in vitro underwent apoptosis with increased intracellular pH via activation of Na+/H+ antiporter, Na+/HCO3-/CO3(2-) cotransporter, or Cl-/HCO3- exchanger. This process does not require de novo protein synthesis.

Activation of the Na(+)/H(+) antiporter, Na+/HCO3(-)/CO3(2-) cotransporter, or Cl(-)/HCO3(-) exchanger in spontaneous thymocyte apoptosis

This study was undertaken to define the role of ion transporters on the apoptosis of thymocytes. Culture conditions, such as the ionic strength of NaCl, Ca2+, the buffer system (HCO3-/CO2), and the pH, could influence the spontaneous apoptosis of thymocytes. Depletion of NaCl in the culture medium either delayed or completely inhibited the apoptotic process of thymocytes, while its restoration led to a dose-dependent apoptosis. A high concentration (100 microM) of Ca2+ induced thymocyte apoptosis in the nominal absence of NaCl, whereas a low concentration (10 microM) enhanced apoptosis in the presence of 138 mM NaCl. Thymocytes had a higher spontaneous apoptotic rate in cultures without HCO3-/CO2 than in those with HCO3-/CO2. The thymocyte apoptosis completely ceased in medium at pH 6.0 and was considerably enhanced at pH 7.6. Intracellular pH, determined with the pH-sensitive bis-carboxyethyl carboxyfluorescein probe, was higher in apoptotic thymocytes than in nonapoptotic cells. Spontaneous apoptosis occurred in cells with alkaline intracellular condition, whereas it was considerably retarded in cells under acidified conditions. Amiloride analogue, including 5-(N,N-dimethyl)-amiloride (Na+/H+ antiporter), 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (Cl-/HCO3- exchanger), and 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonic acid (Na+/HCO3-/CO3(2-) cotransporter), inhibited the spontaneous thymocyte apoptosis. In contrast, neither cycloheximide nor actinomycin D had the same effect. In addition, thymocyte apoptosis was enhanced by PMA, but inhibited by forskolin. Taken together, thymocytes cultured in vitro underwent apoptosis with increased intracellular pH via activation of Na+/H+ antiporter, Na+/HCO3-/CO3(2-) cotransporter, or Cl-/HCO3- exchanger. This process does not require de novo protein synthesis.

Genetic code deviations in the ciliates: evidence for multiple and independent events

In several species of ciliates, the universal stop codons UAA and UAG are translated into glutamine, while in the euplotids, the glutamine codon usage is normal, but UGA appears to be translated as cysteine. Because the emerging position of this monophyletic group in the eukaryotic lineage is relatively late, this deviant genetic code represents a derived state of the universal code. The question is therefore raised as to how these changes arose within the evolutionary pathways of the phylum. Here, we have investigated the presence of stop codons in alpha tubulin and/or phosphoglycerate kinase gene coding sequences from diverse species of ciliates scattered over the phylogenetic tree constructed from 28S rRNA sequences. In our data set, when deviations occur they correspond to in frame UAA and UAG coding for glutamine. By combining these new data with those previously reported, we show that (i) utilization of UAA and UAG codons occurs to different extents between, but also within, the different classes of ciliates and (ii) the resulting phylogenetic pattern of deviations from the universal code cannot be accounted for by a scenario involving a single transition to the unusual code. Thus, contrary to expectations, deviations from the universal genetic code have arisen independently several times within the phylum.

Evidence for intron capture: an unusual path for the evolution of proteins

Most new genes are thought to evolve from preexisting genes but duplications of entire genes or shuffling of preexisting exons provides only a limited repertoire of new sequences that can be presented to a cell. Only pieces that previously existed can be used in the construction and any further divergence depends on the slow accumulation of mutations. We show here the presence of a small, in-frame intron in a ciliate phosphoglycerate kinase gene and the insertion of an unusually random amino acid sequence at the same position in trypanosome phosphoglycerate kinase. The unusual sequences in trypanosomes were likely to have originally been introns that have been subsequently captured by the protein and have now been incorporated as part of the coding sequence. Via this path a truly unique sequence can be incorporated into an existing protein, leading in time to the evolution of a new, functionally distinct protein.

A phylogenetic analysis based on the gene encoding phosphoglycerate kinase

We have determined the nucleotide sequence of both genomic and complementary DNA (cDNA) for the gene encoding the glycolytic enzyme phosphoglycerate kinase from the ciliated protozoan Tetrahymena thermophila. The amino acid sequence for the enzyme has also been derived from the cDNA sequence. The gene contains an open reading frame of 1260 nucleotides encoding 420 amino acids. Coding sequence in genomic DNA is interrupted by two introns at positions corresponding to introns 3 and 4 in mammalian phosphoglycerate kinase genes. The derived amino acid sequence was used to prepare a phylogeny by aligning the Tetrahymena sequence with 25 other phosphoglycerate kinase amino acid sequences. The Tetrahymena sequence is a typical eukaryotic sequence. There is recognizable and clear homology across species that cover nearly the complete range of life forms. The phylogenetic reconstruction of these sequences generally supports the conclusions that have been reached using rRNA sequences.

Synaptonemal complexes from DNase-treated rat pachytene chromosomes contain (GT)n and LINE/SINE sequences

Purified chromosome cores (synaptonemal complexes) of rat pachytene chromosomes, from which the chromatin is removed by extensive DNase II digestion, retain a residual class of DNA, presumably the bases of chromatin loops. This synaptonemal complex-associated DNA, isolated by proteinase digestion and phenol extraction of purified DNase-treated synaptonemal complexes, and cloned in plasmid vector pEMBL18, has a length distribution of 50-500 bp. From a library of these fragments, 21 fragments were sequenced. Present in this sample are short 40-200-bp segments with greater than 80% identity to "long" and "short" interspersed repeated elements (LINE/SINEs), an excess of GT/CA tandem repeats and a number of unidentified sequences. The LINE/SINE segments may play a role in homology vs. nonhomology recognition during meiosis and the alternating purine-pyrimidine sequences have been implicated in genetic recombination. Their enrichment in synaptonemal complexes may be related to the synapsis and recombination functions of meiosis.

Nutritional status of the water-soluble vitamins in an active Chinese elderly population in Hong Kong

Dietary intakes of thiamine, riboflavin, nicotinic and ascorbic acid, together with the biochemical status of thiamine, riboflavin, pyridoxine and ascorbic acid, were determined in a cluster sample of 419 healthy active elderly subjects aged 60 years and above living in the community. Nicotinic acid intake per 1000 kcal (4.18 MJ) of food energy showed an age-related decrease in men, while women had higher ascorbic acid intakes than men. Between 38 and 98 per cent of this population have intakes of thiamine, riboflavin and nicotinic acid below the UK RDA values. Intakes of ascorbic acid were below the RDA for 17 per cent of men and 9 per cent of women. The prevalence of biochemical deficiency was 8, 14, 11.5 and 24 per cent for thiamine, riboflavin, pyridoxine and ascorbic acid respectively. A significant difference in intakes between groups with blood levels within and below the reference range was seen only for riboflavin, suggesting that factors other than low intake may be more important in contributing to low blood levels for thiamine and ascorbic acid. However, inaccuracies in dietary intake estimations may contribute to the poor correlation.

Effects of substituents on ion-association properties. II. 1H N.M.R. studies of substituted pyridinium and tetraalkylammonium Bis(4-methylbenzene-1,2-dithiolato)cobaltate(III) in non-aqueous solvents

A series of nine compounds containing quaternary ammonium and substituted pyridinium cations and the bis(4-methylbenzene-1,2-dithiolato)cobaltate(III) complex anion have been prepared andtheir ion-pair properties studied by lH n.m.r. spectroscopy. Their concentration association constants in nitrobenzene at 307 K range from 9 to 20. In the pyridinium series of ion pairs, it is concludedfrom the measured isotropic shift ratios that methyl substituents at the meta and para positions favour a geometry where the anion is tilted towards the ring of the cation but the ortho substituents push the anion away from the ring. In the methyltrioctylammonium ion pair, there is linear correlation between the observed isotropic shift of the N-methyl or the N-methylene protons and the dielectric constant of the solvents (E) from 4.56 to 12.3 for the 0.06, 0.09 and 0.12 M solutions. Its implication is discussed in terms of the formation of the ionic clusters of sufficiently large size.

Effects of substituents on ion-association properties. 1H n.m.r. studies of substituted pyridinium tribromo(triphenylphosphine)cobaltate(II) complexes in nitrobenzene

A series of compounds containing substituted pyridinium cations and the tribromo(triphenyl-phosphine)cobaltate(II) complex anion have been prepared and studied by n.m.r. spectroscopy in nitrobenzene at 307 K. It is shown that the electronic and the steric effects of the substituents can affect the ion-association constant. From the measured isotropic shift ratios, it is concluded that two substituents at the meta positions of the pyridine ring move the complex anion away from the ring, whereas a para substituent tends to favour a geometry where the anion is tilted towards the ring.