Genital herpes has played a more important role than any other sexually transmitted infection in driving HIV prevalence in Africa

Background

Extensive evidence from observational studies suggests a role for genital herpes in the HIV epidemic. A number of herpes vaccines are under development and several trials of the efficacy of HSV-2 treatment with acyclovir in reducing HIV acquisition, transmission, and disease progression have just reported their results or will report their results in the next year. The potential impact of these interventions requires a quantitative assessment of the magnitude of the synergy between HIV and HSV-2 at the population level.

Methods and Findings

A deterministic compartmental model of HIV and HSV-2 dynamics and interactions was constructed. The nature of the epidemiologic synergy was explored qualitatively and quantitatively and compared to other sexually transmitted infections (STIs). The results suggest a more substantial role for HSV-2 in fueling HIV spread in sub-Saharan Africa than other STIs. We estimate that in settings of high HSV-2 prevalence, such as Kisumu, Kenya, more than a quarter of incident HIV infections may have been attributed directly to HSV-2. HSV-2 has also contributed considerably to the onward transmission of HIV by increasing the pool of HIV positive persons in the population and may explain one-third of the differential HIV prevalence among the cities of the Four City study. Conversely, we estimate that HIV had only a small net impact on HSV-2 prevalence.

Conclusions

HSV-2 role as a biological cofactor in HIV acquisition and transmission may have contributed substantially to HIV particularly by facilitating HIV spread among the low-risk population with stable long-term sexual partnerships. This finding suggests that prevention of HSV-2 infection through a prophylactic vaccine may be an effective intervention both in nascent epidemics with high HIV incidence in the high risk groups, and in established epidemics where a large portion of HIV transmission occurs in stable partnerships.     

Identification of the endostyle as a stem cell niche in a colonial chordate

Stem cell populations exist in "niches" that hold them and regulate their fate decisions. Identification and characterization of these niches is essential for understanding stem cell maintenance and tissue regeneration. Here we report on the identification of a novel stem cell niche in Botryllus schlosseri, a colonial urochordate with high stem cell-mediated developmental activities. Using in vivo cell labeling, engraftment, confocal microscopy, and time-lapse imaging, we have identified cells with stemness capabilities in the anterior ventral region of the Botryllus' endostyle. These cells proliferate and migrate to regenerating organs in developing buds and buds of chimeric partners but do not contribute to the germ line. When cells are transplanted from the endostyle region, they contribute to tissue development and induce long-term chimerism in allogeneic tissues. In contrast, cells from other Botryllus' regions do not show comparable stemness capabilities. Cumulatively, these results define the Botryllus' endostyle region as an adult somatic stem cell niche.     

The anti-fibrotic effect of liver growth factor is associated with decreased intrahepatic levels of matrix metalloproteinases 2 and 9 and transforming growth factor beta 1 in bile duct-ligated rats

Liver growth factor (LGF), a mitogen for liver cells, behaves as an anti-fibrotic agent even in extrahepatic sites, but its mechanistic basis is unknown. We aimed to determine the intrahepatic expression pattern of key modulators of liver fibrosis in bile duct-ligated rats (BDL) after injection of LGF. BDL rats received either LGF (4.5 microg/ratXdose, two doses/week, at time 0 or 2 or 5w after operation, depending on the group (BDL+LGF groups, n=20) or saline (BDL+S groups, n=20). Groups were compared in terms of fibrosis (histomorphometry), liver function (aminopyrine breath test), matrix metalloproteinases MMP-2 and MMP-9, transforming growth factor beta 1 (TGF-beta1) and liver endoglin content (Western blotting), and serum tissue inhibitor of metalloproteinases 1 (TIMP-1) levels (ELISA). In BDL+LGF rats, the fibrotic index was significantly lower at 5w, p=0.006, and at 8w, p=0.04, than in BDL+S rats. Liver function values in BDL+LGF rats were higher than those obtained in BDL+S rats (80% at 5w and 79% at 8w, versus 38% and 29%, p<0.01, taking healthy controls as 100%). Notably, in BDL+LGF rats the intrahepatic expression levels of both MMPs were lower at 2w (MMP-2, p=0.03; MMP-9, p=0.05) and 5w (MMP-2, p=0.05, MMP-9, p=0.04). In addition, the hepatic TGF-beta1 level in BDL+LGF rats was lower at 2w (36%, p=0.008), 5w (50%) and 8wk (37%), whereas intrahepatic endoglin expression remained constant in all BDL rats studied. LGF ameliorates liver fibrosis and improves liver function in BDL rats. The LGF-induced anti-fibrotic effect is associated with a decreased hepatic level of MMP-2, MMP-9 and TGF-beta1 in fibrotic rats.     

Advantages of q-PCR as a method of screening for gene targeting in mammalian cells using conventional and whole BAC-based constructs

We evaluate here the use of real-time quantitative PCR (q-PCR) as a method for screening for homologous recombinants generated in mammalian cells from either conventional gene-targeting constructs or whole BAC-based constructs. Using gene-targeted events at different loci, we show that q-PCR is a highly sensitive and accurate method for screening for conventional gene targeting that can reduce the number of clones requiring follow-up screening by Southern blotting. We further compared q-PCR to fluorescent in situ hybridization (FISH) for the detection of gene-targeting events using full-length BAC-based constructs designed to introduce mutations either into one gene or simultaneously into two adjacent genes. We find that although BAC-based constructs appeared to have high rates of homologous recombination when evaluated by FISH, screening by FISH was prone to false positives that were detected by q-PCR. Our results demonstrate the utility of q-PCR as a screening tool for gene targeting and further highlight potential problems with the use of whole BAC-based constructs for homologous recombination.     

Antioxidant Defenses in Fish: Biotic and Abiotic Factors

Oxygen in its molecular state O₂, is essential for many metabolic processes that are vital to aerobic life. Aerobic organisms cannot exist without oxygen, which nevertheless is inherently dangerous to their lives. Like all aerobic organisms, fish are also susceptible to the effects of reactive oxygen and have inherent and effective antioxidant defenses that are well described in the literature. This review investigates the influence of different biotic and abiotic factors (age, phylogenetic position, feeding behavior, environmental factors, oxygen, temperature, presence of xenobiotics) on antioxidant defenses in fish. Studies of antioxidant activity in fish open a number of novel research lines providing greater knowledge of fish physiology, which will benefit various aspects of fish farming and artificial production.     

Secretion of gastric mucus phospholipids in response to beta-adrenergic G protein-coupled receptor activation is mediated by SRC kinase-dependent epidermal growth factor receptor transactivation.

Recent advances in understanding the nature of cellular responses mediated by G protein-coupled receptor (GPCR) activation indicate that integration of the converging regulatory signals into functional cellular pathways requires epidermal growth factor receptor (EGFR) transactivation. In this study, we report that G protein-coupled beta-adrenergic receptor activation leading to stimulation in gastric mucus phospholipid secretion occurs with the involvement of EGFR. Using [14C]choline-labeled gastric mucosal cells in culture, we show that stimulatory effect of beta-adrenergic agonist, isoproterenol, on phospholipid release was subject to a dose-dependent suppression by EGFR kinase inhibitor, PD153035, as well as wortmannin, a specific inhibitor of PI3K. Both inhibitors, moreover, caused the reduction in the gastric mucosal cell phospholipid secretory responses to beta-adrenergic agonist-generated second messenger, cAMP as well as adenyl cyclase activator, forskolin. The gastric mucosal phospholipid secretory responses to isoproterenol, furthermore, were inhibited by PP2, a selective inhibitor of tyrosine kinase Src responsible for ligand-independent EGFR phosphorylation, but not by ERK inhibitor, PD98059. The inhibition of ERK, moreover, did not cause attenuation in phospholipid secretory responses to cAMP and forskolin. The findings underline the central role of EGFR in mediation of gastric mucosal secretory processes, and demonstrate the requirement for Src kinase-dependent EGFR transactivation in regulation of gastric mucosal phospholipid secretion in response to beta-adrenergic GPCR activation.     

Co-production of ice nuclei and xanthan gum by transformed Xanthomonas campestris grown in sugar beet molasses

Two recombinant plasmids, expressing ice nucleation activity, were constructed and named pCPP30inaZ and pCPP38inaZ. They were transferred to the ice-negative, xanthan-producing Xanthomonas campestris pv. campestris by electroporation. The transformants were used for co-production of xanthan gum and ice nuclei from sugar beet molasses. The highest values obtained were 20 g l^–1 and 10¹⁸ ice nuclei ml^–1, respectively. The above values fulfil the criteria for industrial manipulation. This is the first report on co-formation of two products by a transformed X. campestris strain.     

The nature of ABH blood group antigens in human gastric secretion

The origin of blood group ABH activity in human gastric content was investigated. Dialyzed and lyophilized samples of ten individual gastric secretions were assayed for ABH antigen under various conditions. The native activity persisted in delipidated residue of the respective secretions, but was completely missing in the lipid extracts of the analyzed samples. The alkaline degradation of the native and delipidated samples led to total loss of blood group activity of the analyzed materials, but no effect on A-active glycosphingolipid was evolved. Purified glycolipid portion of the lipid extract was lacking ABH activity and was shown to have distinct composition. This fraction contained only glyceroglucolipids and neither sphingosine nor other carbohydrates were present. On the basis of blood group activity assays of the native, delipidated, alkaline degraded samples and also on glycolipid analysis it was established that the ABH blood group activity of stomach secretion originated entirely from the glycoprotein portion of these samples.