Inhibition of heme oxygenase-1 interferes with the transforming activity of the Kaposi sarcoma herpesvirus-encoded G protein-coupled receptor

Heme oxygenase-1 (HO-1), the inducible enzyme responsible for the rate-limiting step in the heme catabolism, is expressed in AIDS-Kaposi sarcoma (KS) lesions. Its expression is up-regulated by the Kaposi sarcoma-associated herpesvirus (KSHV) in endothelial cells, but the mechanisms underlying KSHV-induced HO-1 expression are still unknown. In this study we investigated whether the oncogenic G protein-coupled receptor (KSHV-GPCR or vGPCR), one of the key KSHV genes involved in KS development, activated HO-1 expression. Here we show that vGPCR induces HO-1 mRNA and protein levels in fibroblasts and endothelial cells. Moreover, targeted knock-down gene expression of HO-1 by small hairpin RNA and chemical inhibition of HO-1 enzymatic activity by tin protoporphyrin IX (SnPP), impaired vGPCR-induced survival, proliferation, transformation, and vascular endothelial growth factor (VEGF)-A expression. vGPCR-expressing cells implanted in the dorsal flank of nude mice developed tumors with elevated HO-1 expression and activity. Chronic administration of SnPP to the implanted mice, under conditions that effectively blocked HO-1 activity and VEGF-A expression in the transplanted cells, strikingly reduced tumor growth, without apparent side effects. On the contrary, administration of the HO-1 inducer cobalt protoporphyrin (CoPP) further enhanced vGPCR-induced tumor growth. These data postulate HO-1 as an important mediator of vGPCR-induced tumor growth and suggest that inhibition of intratumoral HO-1 activity by SnPP may be a potential therapeutic strategy.     

Bacteriocin production, plasmid content and plasmid location of enterocin P structural gene in enterococci isolated from food sources

AIMS: To characterize bacteriocin production, antimicrobial spectrum and plasmid content in bacteriocinogenic enterococci from foods. METHODS AND RESULTS: Bacteriocinogenic Enterococcus faecium (14 isolates) and Enterococcus faecalis (three isolates) showed two different patterns of bacteriocin production in liquid broth: exponential-phase and stationary-phase production. Bacteriocin concentrates from all enterococci were inactivated by trypsin, but seldom by heat (100-117 degrees C), extremes of pH (2.0 to 9.0) or reducing agents (such as dithiothreitol). All bacteriocin concentrates were active against Listeria innocua and Listeria monocytogenes, and most were also active against many Ent. faecalis and Ent. faecium isolates. Enterococci clustered in three main groups according to their plasmid content (which included plasmids from 2.0 to 53 kb). Several isolates from different foods showed almost identical plasmid profiles. The enterocin P structural gene (entP) was detected by hybridization on plasmids of c. 19, 26 and/or 35-38 kb. CONCLUSIONS: Enterococci from food show different patterns of bacteriocin production and different plasmid content in spite of carrying similar bacteriocin-encoding genes. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides information on the diversity of bacteriocinogenic enterococci from food sources carrying apparently similar enterocin genes.     

The molecular epidemiology of Stenotrophomonas maltophilia bacteraemia in a tertiary referral hospital in the United Arab Emirates 2000–2004

Background

Methicillin-resistant Staphylococcus aureus (MRSA) has become increasingly prevalent worldwide since it was first reported in a British hospital. The prevalence however, varies markedly in hospitals in the same country, and from one country to another. We therefore sought to document comprehensively the prevalence and antimicrobial susceptibility pattern of MRSA isolates in Trinidad and Tobago.

Methods

All Staphylococcus aureus isolates encountered in routine clinical specimens received at major hospitals in the country between 2000 and 2001 were identified morphologically and biochemically by standard laboratory procedures including latex agglutination test (Staphaurex Plus; Murex Diagnostics Ltd; Dartford, England); tube coagulase test with rabbit plasma (Becton, Dickinson & Co; Sparks, MD, USA), and DNase test using DNase agar (Oxoid Ltd; Basingstoke, Hampshire, England). MRSA screening was performed using Mueller-Hinton agar containing 6 μg oxacillin and 4% NaCl, latex agglutination test (Denka Seiken Co. Ltd, Tokyo, Japan) and E-test system (AB Biodisk, Solna, Sweden). Susceptibility to antimicrobial agents was determined by the modified Kirby Bauer disc diffusion method while methicillin MICs were determined with E-test system.

Results

Of 1,912 S. aureus isolates received, 12.8% were methicillin (oxacillin) resistant. Majority of the isolates were recovered from wound swabs (86.9%) and the least in urine (0.4%) specimens. Highest number of isolates was encountered in the surgical (62.3%) and the least from obstetrics and gynaecology (1.6%) facilities respectively. Large proportions of methicillin sensitive isolates are >85% sensitive to commonly used and available antimicrobials in the country. All MRSA isolates were resistant to ceftriaxone, erythromycin, gentamicin and penicillin but were 100% sensitive to vancomycin, rifampin and chloramphenicol.

Conclusion

There is a progressive increase in MRSA prevalence in the country but the present rate is still low in comparison to values in some other countries. Vancomycin is still the drug of choice for treating multidrug resistant MRSA infections. Further use of molecular studies to monitor the epidemiology of MRSA in these hospitals in the country is highly recommended too.     

Nordihydroguaiaretic acid is a potent in vitro scavenger of peroxynitrite, singlet oxygen, hydroxyl radical, superoxide anion and hypochlorous acid and prevents in vivo ozone-induced tyrosine nitration in lungs

The antioxidant nordihydroguaiaretic acid (NDGA) has recently become well known as a putative anticancer drug. In this paper, it was evaluated the in vitro peroxynitrite (ONOO(-)), singlet oxygen ((1)O(2)), hydroxyl radical (OH(v)), hydrogen peroxide (H(2)O(2)), superoxide anion and hypochlorous acid (HOCl) scavenging capacity of NDGA. It was found that NDGA scavenges: (a) ONOO(-) (IC(50) = 4 +/- 0.94 microM) as efficiently as uric acid; (b) (1)O(2) (IC(50) = 151 +/- 20 microM) more efficiently than dimethyl thiourea, lipoic acid, N-acetyl-cysteine and glutathione; (c) OH(v) (IC(50) = 0.15 +/- 0.02 microM) more efficiently than dimethyl thiourea, uric acid, trolox, dimethyl sulfoxide and mannitol, (d) (IC(50) = 15 +/- 1 microM) more efficiently than N-acetyl-cysteine, glutathione, tempol and deferoxamine and (e) HOCl (IC(50) = 622 +/- 42 microM) as efficiently as lipoic acid and N-acetyl-cysteine. NDGA was unable to scavenge H(2)O(2). In an in vivo study in rats, NDGA was able to prevent ozone-induced tyrosine nitration in lungs. It is concluded that NDGA is a potent in vitro scavenger of ONOO(-), (1)O(2), OH(v), and HOCl and is able to prevent lung tyrosine nitration in vivo.     

新疆杏仁抗突变作用的实验研究

目的:应用小鼠骨髓嗜多染红细胞(PCE)微核检测试验以探讨杏仁抗突变作用。方法:采用小鼠嗜多染红细胞和有核细胞-微核率(MCN‰)检测法,研究它潜在的抗突变性。结果:该结果能表明杏仁对两种阳性对照组分别诱发的较高微核率有明显降低作用,而且特殊环境下嗜多染红细胞比有核细胞具有较高的敏感性,差异均为非常显著(P<0.001)。结论:杏仁有抗突变,保护染色体损伤,促进DNA修复作用。此项研究抗突变性食物开发和医疗保健中具有重要实际意义。     

Identification of plasma protein biomarkers associated with idiopathic pulmonary arterial hypertension

We have employed SELDI-TOF MS to screen for differentially expressed proteins in plasma samples from 27 patients with idiopathic pulmonary arterial hypertension (IPAH) and 26 healthy controls. One ion (m/z approximately 8600) that was found to be elevated in IPAH was validated by SELDI-TOF MS analysis of a second and separate set of plasma samples comprising 30 IPAH patients and 19 controls. The m/z 8600 was purified from plasma by sequential ion exchange and reverse-phase chromatographies and SDS-PAGE. It was identified, following trypsin digestion, by MS peptide analysis as the complement component, complement 4a (C4a) des Arg. Plasma levels of C4a des Arg measured by ELISA confirmed that the levels were significantly higher (p < 0.0001) in IPAH patients (2.12 +/- 0.27 microg/mL) compared with normal controls (0.53 +/- 0.05 microg/mL). A cut-off level of 0.6 microg/mL correctly classified 92% of IPAH patients and 80% of controls. Further studies will be needed to determine its performance as a diagnostic biomarker, whether used alone or in combination with other biomarkers. Nevertheless, this study demonstrates that putative biomarkers characteristic of IPAH can be identified using a conjoint SELDI-TOF MS - proteomics approach.     

Arbuscular mycorrhizal fungi enhance fruit growth and quality of chile ancho (Capsicum annuum L. cv San Luis) plants exposed to drought

The effect of arbuscular mycorrhizal fungi (AMF) and drought on fruit quality was evaluated in chile ancho (Capsicum annuum L. cv San Luis). AMF treatments were (1) Glomus fasciculatum (AMFG), (2) a fungal species consortium from the forest “Los Tuxtla” in Mexico (AMFT), (3) a fungal species consortium from the Sonorian desert in Mexico (AMFD), and (4) a noninoculated control (NAMF). Plants were exposed to a 26-day drought cycle. Fruit quality was determined by measuring size (length, width, and pedicel length), color, chlorophyll, and carotenoid concentration. Under nondrought conditions, AMFG produced fruits that were 13% wider and 15% longer than the NAMF treatment. Under nondrought conditions, fruit fresh weight was 25% greater in the AMFG treatment compared to the NAMF. Under drought, fruits in the AMFT and AMFD treatments showed fresh weights similar to those in the NAMF treatment not subjected to drought. Fruits of the AMFG treatment subjected to drought showed the same color intensity and chlorophyll content as those of the nondroughted NAMF treatment and carotenoid content increased 1.4 times compared to that in the NAMF not exposed to drought. It is interesting to note that fruits in the AMFD treatment subjected to drought and the NAMF treatment not exposed to drought reached the same size. AMFD treatment increased the concentration of carotenes (1.4 times) under nondrought conditions and the concentration of xanthophylls (1.5 times) under drought when compared to the nondroughted NAMF treatment.     

(Sub)microscopic Plasmodium falciparum gametocytaemia in Kenyan children after treatment with sulphadoxine-pyrimethamine monotherapy or in combination with artesunate

The effects of drugs on Plasmodium falciparum transmission stages may reduce the spread of parasites in the population and contribute to malaria control. Detailed quantitative studies on (sub)microscopic gametocytaemia have become feasible with the availability of real-time Pfs25 quantitative Nucleic Acid Sequence-based Amplification (QT-NASBA), which can be used to detect gametocyte densities above 20 gametocytes per millilitre from in vitro cultures. Gametocyte dynamics were investigated in children with uncomplicated P. falciparum malaria after treatment with sulphadoxine-pyrimethamine (SP) or a combination of SP and artesunate (SP+AS), in a 28-days drug efficacy study. This study demonstrated that gametocyte prevalence in 873 samples from symptomatic Kenyan children was 2.8 times higher by QT-NASBA compared with microscopy. Microscopy-positive cases showed a significant correlation with QT-NASBA for gametocyte density. At enrolment, gametocyte prevalence was 86% by QT-NASBA compared with 22% by microscopy. Gametocytes were detected in 97% of children in at least one blood sample and in 38% of children in all samples obtained during the 28-days follow-up. Both the risk of gametocyte carriage and gametocyte density were considerably higher after treatment with SP compared with SP+AS. Gametocyte prevalence and density decreased with time in the SP+AS group, but not in the SP-treated children. Our data suggest that the potential of malaria transmission remains high even after treatment with artemisinin combination therapy, although prevalence and density of gametocytes is lower after SP+AS.