Hepatitis B virus (HBV) genotypes can influence treatment outcome in HBV-monoinfected and human immunodeficiency virus (HIV)/HBV-coinfected patients. Tenofovir disoproxil fumarate (TDF) plays a ...pivotal role in antiretroviral therapy (ART) of HIV/HBV-coinfected patients. The influence of HBV genotypes on the response to antiviral drugs, particularly TDF, is poorly understood.
HIV/HBV-co-infected participants with detectable HBV DNA prior to TDF therapy were selected from the Swiss HIV Cohort Study. HBV genotypes were identified and resistance testing was performed prior to antiviral therapy, and in patients with delayed treatment response (>6 months). The efficacy of TDF to suppress HBV (HBV DNA <20 IU/mL) and the influence of HBV genotypes were determined.
143 HIV/HBV-coinfected participants with detectable HBV DNA were identified. The predominant HBV genotypes were A (82 patients, 57 %); and D (35 patients, 24 %); 20 patients (14 %) were infected with multiple genotypes (3 % A + D and 11 % A + G); and genotypes B, C and E were each present in two patients (1 %). TDF completely suppressed HBV DNA in 131 patients (92 %) within 6 months; and in 12 patients (8 %), HBV DNA suppression was delayed. No HBV resistance mutations to TDF were found in patients with delayed response, but all were infected with HBV genotype A (among these, 5 patients with genotype A + G), and all had previously been exposed to lamivudine.
In HIV/HBV-coinfected patients, infection with multiple HBV genotypes was more frequent than previously reported. The large majority of patients had an undetectable HBV viral load at six months of TDF-containing ART. In patients without viral suppression, no TDF-related resistance mutations were found. The role of specific genotypes and prior lamivudine treatment in the delayed response to TDF warrant further investigation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To assess the prevalence of abnormal testosterone and gonadotropin values in HIV-infected men before and after 2 years of combination antiretroviral therapy (cART).
Multicentre cohort of HIV-infected ...adults.
We identified 139 Caucasian antiretroviral-naive male patients who started zidovudine/ lamivudine-based cART that was virologically successful over a 2 year period. Ninety-seven were randomly chosen and plasma hormone determinations of free testosterone (fT) and luteinizing hormone (LH) at baseline and after 2 years of cART were evaluated.
At baseline 68 patients (70%) had subnormal fT levels. In these, LH levels were low in 44%, normal in 47% and high in 9%. There was a trend for an association between lower CD4+ T-cell counts and hypogonadism. Most participants had normal FSH levels. No significant changes of fT, LH and FSH levels were observed after 2 years of cART.
Low fT levels, mainly with normal or low LH levels and thus indicating secondary hypogonadism, are found in the majority of HIV-infected men and do not resolve during 2 years of successful cART.
We examined the extent of grazing damage to seedlings of white clover (
Trifolium repens) in experimentally fragmented calcareous grasslands. The experimental set-up consisted of 12 blocks ...distributed over three sites. Each block contained one large (4.5 × 4.5 m), one medium (1.5 × 1.5 m) and two small (0.5 × 0.5 m) fragments and corresponding control plots. Fragmentation was maintained by frequently mowing the area between the fragments. A fence around the study sites excluded large herbivores. Seedlings of
T. repens planted in petri dishes were exposed to invertebrate herbivores in fragments and control plots for 2–3 days both in summer and autumn. In summer—unlike autumn—grazing intensity expressed as leaf biomass loss per petri dish and day was 43% lower in fragments than in control plots. Grazing intensity in summer was positively correlated with relative gastropod density (number of individuals from 12 species), but not with relative grasshopper density (number of individuals from 15 species). In autumn, grazing intensity was correlated neither with gastropod nor with grasshopper density. It is suggested that a combination of factors can explain the seasonal difference in fragmentation effect on grazing intensity. Different herbivore species are active at different seasons and/or under different environmental conditions. Furthermore, different herbivore species react differently to the type of grassland fragmentation chosen in the present study. We conclude that fragmentation effects on grazing depend on which of the potential herbivore species react to fragmentation and which of them are active during the investigation period.
Species richness and abundance of vascular plants and several groups of invertebrates (spiders, oribatid mites, diplopods, grasshoppers and bush crickets, ground beetles, butterflies and terrestrial ...gastropods) were recorded in three calcareous grasslands (Nenzlingen, Movelier and Vicques) in the northwestern Swiss Jura mountains. Species richness varied both between taxonomical groups and between sites (species richness ranges: 96-116 vascular plants, 60-66 spiders, 18 oribatid mites at each site, 1-7 diplopods, 10-16 grasshoppers and bush crickets, 19-21 ground beetles, 32-46 butterflies and 15-21 terrestrial gastropods). Species overlap (number of species that occurred at all sites) was relatively large in terrestrial gastropods (59.1%), butterflies (56.5%), vascular plants (53.8%) and grasshoppers (47.1%), but relatively low in orbatid mites (32.3%), spiders (25.0%), ground beetles (18.4%) and diplopods (12.5%). Diversity expressed by the Shannon-Wiener index (H') was compared for five groups of invertebrates. Diversity was largest in spiders and ground beetles and lowest in terrestrial gastropods. Different taxonomical groups had their maximum diversity at different sites: each grassland had the highest diversity in at least one group. The three sites also varied in the abundance of different invertebrate groups. Most groups had the highest densities in Nenzlingen and the lowest densities in Vicques. All three sites contained a high proportion of species listed in the Red Data Book of Switzerland with values averaging 49.5% in grasshoppers and bush crickets, 28.9% in butterflies, 18.9% in vascular plants, 11.2% in terrestrial gastropods, and 6.7% in ground beetles. One spider species (Oxyptila pullata) and two mite species (Epilohmannia cylindrica minima and Pergalumna myrmophila) were recorded for the first time in Switzerland.
Plant-herbivore interactions may change as atmospheric CO
2 concentrations continue to rise. We examined the effects of elevated atmospheric CO
2 and CO
2-exposure chambers on the grazing damage to ...plants, and on the abundances of potential herbivores (terrestrial gastropods and grasshoppers) in a calcareous grassland in the Jura mountains of Switzerland (village of Nenzlingen). Individuals of most plant species examined showed slight grazing damage. However, plots with CO
2 enrichment and plots with ambient atmosphere did not differ in the extent of grazing damage. Similarly, plots with CO
2 enrichment and plots with ambient atmosphere did not differ in either gastropod or grasshopper density. Experimental plots with and without chambers did not differ in the number of gastropods. However, the densities of gastropods and grasshoppers and extent of grazing damage to plants were generally lower in the experimental area than in the grassland outside the experimental field.
Les interactions plante-herbivore pourraient changer avec l'augmentation des concentrations en CO
2 de l'atmosphère. Nous avons étudié les effets d'une élévation du CO
2 atmosphérique sur les dégâts occasionnés aux plantes par le broutage et sur l'abondance d'herbivores potentiels (gastéropodes terrestres et sauterelles) dans une prairie calcaire du Jura suisse (village de Nenzlingen). Les individus de la plupart des espèces végétales étudiées présentent de légers dégâts dus au broutage. Néanmoins, il n'y a pas de différence dans l'étendue des dégâts entre les placettes enrichies en CO
2 et les témoins. De la même manière, les densités de gastéropodes et de sauterelles ne diffèrent pas entre les placettes enrichies en CO
2 et les placettes témoins. Le nombre de gastéropodes ne diffère pas selon que les placettes expérimentales sont équipées de chambres ou non. Cependant, les densités de gastéropodes et de sauterelles ainsi que l'étendue des dégâts sont généralement moins élevées dans la zone expérimentale qu'à l'extérieur de celle-ci.
The feeding behaviour of juveniles of the land snail
Helix pomatia was examined in model plant communities consisting of
Trifolium repens,
Hieracium pilosella,
Bromus erectus and
Prunella vulgaris ...that are common species in extensively managed calcareous grasslands in the Swiss Jura mountains. The plant communities were grown either at ambient (350 ppm) or elevated (600 ppm) CO
2 concentrations. Leaves of
T. repens and
P. vulgaris grown in elevated atmospheric CO
2 had a lower specific leaf area, and leaves of
T. repens had lower percentage N on a dry weight basis than leaves grown under ambient CO
2 concentration. Snails fed on all four plant species, but showed a overwhelming preference for
T. repens (percentages of total biomass consumed were 91.9% at 350 ppm and 97.6% at 600 ppm). The species-specific feeding intensity of juvenile
H. pomatia did not differ between the two treatments. The total dry weight of
T. repens consumed by the snails was marginally greater (
P = 0.06) at elevated CO
2, but there were no significant differences in leaf N or leaf area eaten. These findings are similar to numerous other studies showing that invertebrates increase their consumption of plant material to balance reductions in plant N concentrations at elevated CO
2. The leaf biomass, leaf area and amount of nitrogen consumed of the other three plant species did not differ significantly between the two CO
2 treatments.
Helix pomatia that fed on plants grown at elevated CO
2 atmosphere showed a larger increase in relative wet weight than those that fed on plants from ambient CO
2 conditions. However, the weight gain of
H. pomatia was poorly correlated with amount of plant tissue consumed, so we suggest that the effect of CO
2 on weight gain in
H. pomatia was due to a change in the quality of
T. repens leaves.
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