Secondary dune succession on Inhaca Island,Mozambique

Old field succession was studied on coastal dunes supporting tropical evergreen forest on Inhaca Island, Mozambique. Plots of 10×10 m were sited in three early successional stages and in relatively undisturbed forest. Woody species increased in number during succession; leptophylls were most frequent in younger vegetation, whereas microphylls and mesophylls were most frequent in forest. Grasses, shrubs and forbs dominated initially following abandonment, and shrubs persisted as dominants in the three early successional stages. The initial floristic composition model was generally supported by the pattern of species sequences, with many forest species entering early in the succession. Of the few species conforming to the relay floristic model, many were grasses and forbs of the forest understorey. Similarity between plots of equivalent vegetation age indicated that, at least in early succession, there was linearity in the successional pathway; there was no evidence for divergence or multiple pathways. In early succession, no accumulation was detected in either soil organic matter or extractable nutrients, thus providing little support for the facilitation model of succession. It is stressed that the findings are probably scale-dependent.     

IUMS News International Union of Microbiological Societies Newsletter

IUMS NewsInternational Union of Microbiological Societies Newsletter     

Predictors of severe stenosis at invasive coronary angiography in patients with normal myocardial perfusion imaging

Purpose

Normal myocardial perfusion imaging (MPI) is associated with excellent prognosis. However, in patients with persisting symptoms, it may be difficult to determine the patients in whom invasive angiography is justified to rule out false negative MPI. We evaluated predictors for severe stenosis at invasive angiography in patients with persisting symptoms after normal MPI.

Methods

229 consecutive patients with normal MPI, without previous bypass surgery, underwent invasive angiography within 6 months. Older age was defined as >65 years. Multivariable analyses were performed to adjust for differences in baseline variables.

Results

Mean age was 62?±?11 years, 48% were women. Severe stenosis was observed in 34%, and of these patients 60% had single-vessel disease (not left main coronary artery disease). After adjusting for several variables, including diabetes, smoking status, hypertension and hypercholesterolaemia, predictors of severe stenosis were male gender, odds ratio (OR) 2.7 (95% confidence interval (CI) 1.5–4.9), older age, OR 1.9 (95% CI 1.02–3.54) previous PCI, OR 2.0 (95% CI 1.0–4.3) and typical angina, OR 2.5 (95% CI 1.4–4.6).

Conclusions

Increasing age, male gender, previous PCI and typical symptoms are predictors of severe stenosis at invasive coronary angiography in patients with normal MPI. The majority of these patients have single-vessel disease.

     

Quantifying the Precision of Single-Molecule Torque and Twist Measurements Using Allan Variance

Single-molecule manipulation techniques have provided unprecedented insights into the structure, function, interactions, and mechanical properties of biological macromolecules. Recently, the single-molecule toolbox has been expanded by techniques that enable measurements of rotation and torque, such as the optical torque wrench (OTW) and several different implementations of magnetic (torque) tweezers. Although systematic analyses of the position and force precision of single-molecule techniques have attracted considerable attention, their angle and torque precision have been treated in much less detail. Here, we propose Allan deviation as a tool to systematically quantitate angle and torque precision in single-molecule measurements. We apply the Allan variance method to experimental data from our implementations of (electro)magnetic torque tweezers and an OTW and find that both approaches can achieve a torque precision better than 1 pN · nm. The OTW, capable of measuring torque on (sub)millisecond timescales, provides the best torque precision for measurement times$\mathrm{?}$10 s, after which drift becomes a limiting factor. For longer measurement times, magnetic torque tweezers with their superior stability provide the best torque precision. Use of the Allan deviation enables critical assessments of the torque precision as a function of measurement time across different measurement modalities and provides a tool to optimize measurement protocols for a given instrument and application.     

Biomonitoring with the BuzzardButeo buteo in the Netherlands: Heavy metals and sources of variation

The feasibility of using Buzzards found dead as indicators of environmental contamination was tested. Liver, kidney, and tibia specimens were examined for the presence of Cd, Cu, Pb, Mn, and Fe, which were used as markers. All buzzards submitted to the Veterinary Institute in 1992 were examined for cause of death and condition. Results showed that more than half had been poisoned or shot. As the condition of the birds worsened, fat reserves were depleted before protein reserves. Concentrations of the heavy metals rose in liver and kidney as nutrient reserves fell. Since the content of heavy metal per organ was not related to body condition, content was considered a better measure for biomonitoring. The concentrations of Cd, Cu, Pb, Mn, or Fe measured in buzzards were not toxic. In several places buzzards had recently ingested relatively large amounts Cd and/or Pb. Buzzards with high contents of Cd, Cu, Pb, and Mn were found in areas having more than average contamination. The North-South gradient in aerosol deposition and soil content of heavy metals (especially Cd & Pb) was reflected in the Buzzard. We concluded that the Buzzard is a suitable and cost-effective biomonitor, to investigate the bioavailability of ecocontaminants in large areas, to signal gross changes in food webs, and to monitor raptor persecution.     

A new allele of the lurcher gene, lurcher

A new neurological mouse mutation that arose spontaneously in a BALB/cByJ stock displays a semidominant pattern of inheritance. In the heterozygote, this mutation results in an early loss of Purkinje cells in the cerebellum, which is followed by the overt symptom of an ataxic gait first observed at postnatal day 13 (P13). A portion of animals homozygous for the mutation die within P0; the remaining homozygotes die by P25. The mutation maps to mouse Chromosome (Chr) 6 between markers D6Rck314 and D6Rck361, a chromosomal segment that contains the lurcher (Lc) locus. The Lc mutation is also semidominant and has a strikingly similar phenotype. A cross between a new mutant (Nm) heterozygote and an Lc heterozygote yields double heterozygotes, animals that carry both mutations, with a phenotype similar to that of both Nm and Lc homozygotes. The similarity in phenotype, the colocalization of the two loci on mouse Chr 6, and the positive result of the allelism test demonstrate that the new mutation is an allele of the Lc gene. Received: 4 April 1997 / Accepted: 21 April 1997     

APL1, an altered peptide ligand derived from human heat-shock protein 60, increases the frequency of Tregs and its suppressive capacity against antigen responding effector CD4 + T cells from rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by a chronic relapsing-remitting joint inflammation. Perturbations in the balance between CD4?+?T cells producing IL-17 and CD4?+?CD25^highFoxP3?+?Tregs correlate with irreversible bone and cartilage destruction in RA. APL1 is an altered peptide ligand derived from a CD4+ T-cell epitope of human HSP60, an autoantigen expressed in the inflamed synovium, which increases the frequency of CD4?+?CD25^highFoxP3+ Tregs in peripheral blood mononuclear cells from RA patients. The aim of this study was to evaluate the suppressive capacity of Tregs induced by APL1 on proliferation of effector CD4+ T cells using co-culture experiments. Enhanced Treg-mediated suppression was observed in APL1-treated cultures compared with cells cultured only with media. Subsequent analyses using autologous cross-over experiments showed that the enhanced Treg suppression in APL1-treated cultures could reflect increased suppressive function of Tregs against APL1-responsive T cells. On the other hand, APL1-treatment had a significant effect reducing IL-17 levels produced by effector CD4+ T cells. Hence, this peptide has the ability to increase the frequency of Tregs and their suppressive properties whereas effector T cells produce less IL-17. Thus, we propose that APL1 therapy could help to ameliorate the pathogenic Th17/Treg balance in RA patients.     

Biomarker Profiles in Women with PCOS and PCOS Offspring; A Pilot Study

ObjectiveTo study metabolic/inflammatory biomarker risk profiles in women with PCOS and PCOS offspring.DesignCross-sectional comparison of serum biomarkers.SettingUniversity Medical Center Utrecht.PatientsHyperandrogenic PCOS women (HA-PCOS, n = 34), normoandrogenic PCOS women (NA-PCOS, n = 34), non-PCOS reference population (n = 32), PCOS offspring (n = 14, age 6–8 years), and a paedriatic reference population (n = 30).ResultsThe cluster analysis identified leptin, RBP-4, DPP-IV and adiponectin as potential discriminative markers for HA-PCOS with a specifically strong correlation in cases with increased BMI. Leptin (R² = 0.219) and adiponectin (R² = 0.182) showed the strongest correlation with the FAI. When comparing median protein concentrations adult PCOS women with or without hyperandrogenemia, the most profound differences were observed for leptin (P < 0.001), DPP-IV (P = 0.005), and adiponectin (P < 0.001). Adjusting for age, BMI and multiple testing attenuated all differences. In PCOS offspring, MMP-9 (P = 0.001) and S100A8 (P < 0.001) concentrations were significantly higher compared to a healthy matched reference population, even after correcting for age and BMI and adjustment for multiple testing.ConclusionIn this preliminary investigation we observed significant differences in adipocytokines between women with or without hyperandrogenic PCOS and non-PCOS controls, mostly influenced by BMI. Leptin and adiponectin showed the strongest correlation with the FAI in adult women with PCOS. In PCOS offspring other inflammatory biomarkers (MMP-9, S100A8) were increased, suggesting that these children may exhibit increased chronic low-grade inflammation. Additional research is required to confirm results of the current exploratory investigation.