The Influence of Alarm Substance on Feeding in Zebra Danio Fish (Brachydanio rerio)

The effects of alarm substance on feeding behaviour of zebra danio fish (Brachydanio rerio) were tested by offering them high and low densities of enclosed waterfleas (Daphnia magna). Normally the fish attacked high densities of prey, but when exposed to alarm substance they preferred lower and presumably less confusing prey densities — also lowering their feeding rate.     

The effect of acetic acid and specific growth rate on acetic acid tolerance and trehalose content of Saccharomyces cerevisiae

Summary The effects of acetic acid and specific growth rate on acetic acid tolerance and trehalose content of Saccharomyces cerevisiae CBS 2806 were studied using anaerobic chemostat cultures. Cells grown in the presence of acetic acid at a defined specific growth rate showed a higher acetic acid tolerance and a slightly lower trehalose content. Cells grown at a low specific growth rate showed a lower energy demand, a higher acetic acid tolerance, and a higher trehalose content. These results indicate that trehalose plays a growth rate dependent role in the tolerance of S. cerevisiae to acetic acid.     

Direct application of carbendazim and propiconazole at field rates to the external mycelium of three arbuscular mycorrhizal fungi species: effect on 32P transport and succinate dehydrogenase activity

 The influence of the systemic fungicides propiconazole (Tilt 250E) and carbendazim (Bavistin) at field application rates on the functioning of three arbuscular mycorrhizal fungi was studied. Short-term fungal ³²P transport and succinate dehydrogenase (SDH) activity in external hyphae of Glomus intraradices Schenck and Smith, G. claroideum Schenck and Smith and G. invermaium Hall in symbiosis with pea (Pisum sativum L.) were measured. In the experimental system used, the hyphae grew into two root-free hyphal compartments (HCs). The fungicides were applied to each HC 24 days after sowing and ³²P was added to one HC of each pot. Four days later, the fungicide effect on fungal P transport was measured as the difference in ³²P content of treated and untreated plants. SDH activity in fungal hyphae was determined in the HCs given no ³²P. Carbendazim severely inhibited ³²P transport and SDH activity in external hyphae at an application rate of 0.5 μg g^–1 soil. The ergosterol inhibitor propiconazole affected none of these parameters. The fungicides had similar effects on all three fungal species, although P transport efficiency and SDH activity differed markedly between the fungi. Accepted: 12 December 1996     

Concentration-dependent effects of potassium dichromate on the cell cycle

Hexavalent chromium is found to be a strong mutagen, and it also is a potential carcinogen in man. DNA flow cytometry, growth measurements, and determinations of mitotic index show that 1-2 microM K2Cr2O7 produces a prolongation of the G2 phase of the cell cycle in NHIK 3025 cells. By increasing the chromate concentrations (greater than 2 microM K2Cr2O7) the cells are also arrested in G2 phase. We have found, using synchronized cells and measuring cell cycle time, that the most chromate-sensitive part of the cell cycle is S phase. This phase is also somewhat prolonged, and the cells became arrested in early S phase at high toxic K2Cr2O7 concentrations (8 microM). Our results thus indicate that K2Cr2O7 has an effect within S phase--maybe on DNA/RNA synthesis--and also interferes with processes necessary for progression through the G2 phase.     

The use of trout erythrocytes and human lymphocytes for standardization in flow cytometry

A method of standardization of flow cytometric ploidy measurements using trout erythrocytes and human lymphocytes is described. The sources of errors of the ratio between the modal channel number of erythrocytes and lymphocytes were investigated. The sample standard deviation was 0.3%, and the variation between persons of the same sex was approximately 0.5%. A distinct difference (1.82%) between the two sexes indicated that small deviations of DNA content can be detected. The standardization method was applied to the analysis of biopsy specimens from bladder tumors, normal bladder mucosa, and lymphocytes from the same patients. In diploid populations the standard deviation of the DNA indices was 1.5-2% for normal bladder mucosa but approximately 2.5% for tumors. These values indicate that deviations amounting to 4-5% from the diploidy are detectable by a single analysis of one sample.     

The occrrence of vesicular-arbuscular mycorrhiza in barley and wheat grown in some Danish soils with different fertilizer treatments

Summary Soil samples, roots and shoots were collected from barley crops at three locations which had received different combinations of N and P for 10 years, and from long-term fertilizer experiments on barley in a sandy soil and on barley and wheat in a loamy soil.Soils were analysed for available P by an anion exchange resin procedure, roots were examined for intensity of VAM infection, and shoots wee analysed for N and P.Vesicualr-arbuscular mycorrhizal infection was found at all locations. It was most abundant at the three locations with least soil-P and lightest at the two locations high in soil-P. Within loocations an inverse relation was found between soil-P level and intensity of infection. Infection was also intensity. by increasing N-fertilizer. Spore counts from selected samples correlated well with infection intensity. Shoot-P did not differ significantly between treatments in spite of significant differences in soil-P. This points to the significance of vesicular-arbuscular mycorrhiza: a lower soil-P level accompanied by a higher infection intensity seem to counterbalance each other to a certain extent.     

Pre-Analytical Conditions in Non-Invasive Prenatal Testing of Cell-Free Fetal RHD

Background

Non-invasive prenatal testing of cell-free fetal DNA (cffDNA) in maternal plasma can predict the fetal RhD type in D negative pregnant women. In Denmark, routine antenatal screening for the fetal RhD gene (RHD) directs the administration of antenatal anti-D prophylaxis only to women who carry an RhD positive fetus. Prophylaxis reduces the risk of immunization that may lead to hemolytic disease of the fetus and the newborn. The reliability of predicting the fetal RhD type depends on pre-analytical factors and assay sensitivity. We evaluated the testing setup in the Capital Region of Denmark, based on data from routine antenatal RHD screening.

Methods

Blood samples were drawn at gestational age 25 weeks. DNA extracted from 1 mL of plasma was analyzed for fetal RHD using a duplex method for exon 7/10. We investigated the effect of blood sample transportation time (n = 110) and ambient outdoor temperatures (n = 1539) on the levels of cffDNA and total DNA. We compared two different quantification methods, the delta Ct method and a universal standard curve. PCR pipetting was compared on two systems (n = 104).

Results

The cffDNA level was unaffected by blood sample transportation for up to 9 days and by ambient outdoor temperatures ranging from -10°C to 28°C during transport. The universal standard curve was applicable for cffDNA quantification. Identical levels of cffDNA were observed using the two automated PCR pipetting systems. We detected a mean of 100 fetal DNA copies/mL at a median gestational age of 25 weeks (range 10–39, n = 1317).

Conclusion

The setup for real-time PCR-based, non-invasive prenatal testing of cffDNA in the Capital Region of Denmark is very robust. Our findings regarding the transportation of blood samples demonstrate the high stability of cffDNA. The applicability of a universal standard curve facilitates easy cffDNA quantification.     

The Use of Biatain Ag in Hard-to-Heal Venous Leg Ulcers: Meta-Analysis of Randomised Controlled Trials

Background

Venous leg ulcers are common, troublesome, and their failure to heal is often related to a heavy bio-burden. Ionized silver has both anti-inflammatory and antimicrobial properties. The ulcer healing properties of the silver releasing foam dressing Biatain Ag has been examined in 4 randomized controlled trials (RCTs).

Aim

To evaluate ulcer healing through a meta-analytic approach after treatment with either Biatain Ag or a non-active dressing.

Patients and Methods

685 subjects with pure or mixed hard-to-heal venous leg ulcers were included in the meta-analysis.

Results

Biatain Ag showed a significant treatment effect (p<0.0001), responder rate (p<0.001), and healing rate (p = 0.002).

Conclusion

The meta-analysis of the 4 RCTs provided statistical significant evidence to support the use of Biatain Ag dressing in treatment of hard-to-heal venous leg ulcers.     

Longitudinal Analysis of CCR5 and CXCR4 Usage in a Cohort of Antiretroviral Therapy-Na?ve Subjects with Progressive HIV-1 Subtype C Infection

HIV-1 subtype C (C-HIV) is responsible for most HIV-1 cases worldwide. Although the pathogenesis of C-HIV is thought to predominantly involve CCR5-restricted (R5) strains, we do not have a firm understanding of how frequently CXCR4-using (X4 and R5X4) variants emerge in subjects with progressive C-HIV infection. Nor do we completely understand the molecular determinants of coreceptor switching by C-HIV variants. Here, we characterized a panel of HIV-1 envelope glycoproteins (Envs) (n = 300) cloned sequentially from plasma of 21 antiretroviral therapy (ART)-naïve subjects who experienced progression from chronic to advanced stages of C-HIV infection, and show that CXCR4-using C-HIV variants emerged in only one individual. Mutagenesis studies and structural models suggest that the evolution of R5 to X4 variants in this subject principally involved acquisition of an “Ile-Gly” insertion in the gp120 V3 loop and replacement of the V3 “Gly-Pro-Gly” crown with a “Gly-Arg-Gly” motif, but that the accumulation of additional gp120 “scaffold” mutations was required for these V3 loop changes to confer functional effects. In this context, either of the V3 loop changes could confer possible transitional R5X4 phenotypes, but when present together they completely abolished CCR5 usage and conferred the X4 phenotype. Our results show that the emergence of CXCR4-using strains is rare in this cohort of untreated individuals with advanced C-HIV infection. In the subject where X4 variants did emerge, alterations in the gp120 V3 loop were necessary but not sufficient to confer CXCR4 usage.