A new DNA marker (D4S90) is located terminally on the short arm of chromosome 4, close to the Huntington disease gene

Genetic linkage studies have mapped Huntington's disease (HD) to the distal portion of the short arm of chromosome 4 (4p16.3), 4 cM distal to D4S10 (G8). To date, no definite flanking marker has been identified. A new DNA marker, D4S90 (D5), which maps to the distal region of 4p16.3, is described. The marker was used in a genetic linkage study in the CEPH reference families with seven other markers at 4p16. The study, together with knowledge of the physical map of the region, places D4S90 as the most distal marker, 6 cM from D4S10. A provisional linkage study with HD gave a maximum lod score of 2.14 at a θ of 0.00 and no evidence of linkage disequilibrium. As D4S90 appears to be located terminally, it should play an important role in the accurate mapping and cloning of the HD gene.     

Geitler's “Plattenband” in the diatomSynedra cf.ulna in the light of TEM investigations

The ultrastructure of the diatomSynedra cf.ulna was examined paying special attention to the Plattenband (platelet band). This structure was first described byGeitler in 1948 on the basis of LM observations and denotes a linear array of dictyosomes along the apical axis of the cell. The present investigation confirmsGeitler's observations in all essential details and demonstrates that the dictyosomes are arranged along polarized nuclear extensions running towards the cell poles. Laterally the extensions are accompanied by a number of microtubules. In large cells the total length of the nucleus thus may reach 400 µm and more. Since only the central part of the nucleus is DNA-positive with DAPI and acridine orange, the nuclear nature of the backbone of the Plattenband cannot be recognized by LM techniques. TEM investigation of serial apical and transapical sections, however, prove unambiguously the identity with extended parts of the nucleus.Dedicated to Prof. DrLothar Geitler on the occasion of his 90th birthday.     

Aspects of morphogenesis and function of diatom cell walls with implications for taxonomy

Summary Aspects of morphogenesis and morphology of diatom cell walls are reviewed to highlight functional correlations between wall structures and three-dimensional cytoplasmic activities during the cell cycle. Morphogenesis of the siliceous valve within the silica deposition vesicle is discussed in the light of the dependency on a precisely orchestrated moulding machinery, involving the cytoskeleton, mitochondria, endoplasmic reticulum, spacer vesicles produced by the Golgi apparatus, and the plasmalemma, in combination with adhesion of the cells to parts of the parental wall and localized plasmolyses. Sensitivity of morphogenetic events to fluctuations of external factors has implications for taxonomy.Abbreviations CF cleavage furrows - cPL cleavage plasmalemma - GB girdle bands - LP labiate process - LPA labiate process apparatus - MC microtubule center - mLP macro labiate process - MT microtubule - MTOC microtubules organizing center - PL plasmalemma - SDV silica deposition vesicle - SL SDV membrane - SpV spacer vesicles Dedicated to Professor Peter Sitte on the occasion of his 65th birthday     

Molecular clones of the mouse t complex derived from microdissected metaphase chromosomes

Fragments of the proximal half of mouse chromosome 17 including the t-complex region were microdissected from metaphase spreads. DNA was isolated from a pool of such fragments, and was cloned on microscale. Individual clones were used to probe genomic digests of DNA from a pair of Chinese hamster cell lines with or without mouse chromosome 17, and livers of congenic inbred lines of mice carrying wild-type and/or t-haplotype forms of chromosome 17. The data obtained indicate that 95% of the low copy number microclone inserts recognize DNA sequences present on mouse chromosome 17. It has been possible to use one-third of these clones to identify restriction-fragment-length polymorphisms between wild-type and t-haplotype DNA on a congenic background. These results demonstrate that these clones have been derived from the t-complex or regions closely linked to it. Clones of this type should provide starting points for a molecular analysis of this region of the mouse genome.     

The ‘Antiretrovirals,Sexual Transmission Risk and Attitudes’ (ASTRA) Study. Design,Methods and Participant Characteristics

Life expectancy for people diagnosed with HIV has improved dramatically however the number of new infections in the UK remains high. Understanding patterns of sexual behaviour among people living with diagnosed HIV, and the factors associated with having condom-less sex, is important for informing HIV prevention strategies and clinical care. In addition, in view of the current interest in a policy of early antiretroviral treatment (ART) for all people diagnosed with HIV in the UK, it is of particular importance to assess whether ART use is associated with increased levels of condom-less sex. In this context the ASTRA study was designed to investigate current sexual activity, and attitudes to HIV transmission risk, in a large unselected sample of HIV-infected patients under care in the UK. The study also gathered background information on demographic, socio-economic, lifestyle and disease-related characteristics, and physical and psychological symptoms, in order to identify other key factors impacting on HIV patients and the behaviours which underpin transmission. In this paper we describe the study rationale, design, methods, response rate and the demographic characteristics of the participants. People diagnosed with HIV infection attending 8 UK HIV out-patient clinics in 2011-2012 were invited to participate in the study. Those who agreed to participate completed a confidential, self-administered pen-and-paper questionnaire, and their latest CD4 count and viral load test results were recorded. During the study period, 5112 eligible patients were invited to take part in the study and 3258 completed questionnaires were obtained, representing a response rate of 64% of eligible patients. The study includes 2248 men who have sex with men (MSM), 373 heterosexual men and 637 women. Future results from ASTRA will be a key resource for understanding HIV transmission within the UK, targeting prevention efforts, and informing clinical care of individuals living with HIV.     

Clinical Evaluation of Rega 8: An Updated Genotypic Interpretation System That Significantly Predicts HIV-Therapy Response

Introduction

Clinically evaluating genotypic interpretation systems is essential to provide optimal guidance in designing potent individualized HIV-regimens. This study aimed at investigating the ability of the latest Rega algorithm to predict virological response on a short and longer period.

Materials & Methods

9231 treatment changes episodes were extracted from an integrated patient database. The virological response after 8, 24 and 48 weeks was dichotomized to success and failure. Success was defined as a viral load below 50 copies/ml or alternatively, a 2 log decrease from the baseline viral load at 8 weeks. The predictive ability of Rega version 8 was analysed in comparison with that of previous evaluated version Rega 5 and two other algorithms (ANRS v2011.05 and Stanford HIVdb v6.0.11). A logistic model based on the genotypic susceptibility score was used to predict virological response, and additionally, confounding factors were added to the model. Performance of the models was compared using the area under the ROC curve (AUC) and a Wilcoxon signed-rank test.

Results

Per unit increase of the GSS reported by Rega 8, the odds on having a successful therapy response on week 8 increased significantly by 81% (OR = 1.81, CI = [1.76–1.86]), on week 24 by 73% (OR = 1.73, CI = [1.69–1.78]) and on week 48 by 85% (OR = 1.85, CI = [1.80–1.91]). No significant differences in AUC were found between the performance of Rega 8 and Rega 5, ANRS v2011.05 and Stanford HIVdb v6.0.11, however Rega 8 had the highest sensitivity: 76.9%, 76.5% and 77.2% on 8, 24 and 48 weeks respectively. Inclusion of additional factors increased the performance significantly.

Conclusion

Rega 8 is a significant predictor for virological response with a better sensitivity than previously, and with rules for recently approved drugs. Additional variables should be taken into account to ensure an effective regimen.     

A highly sensitive molecular structural probe applied to in situ biosensing of metabolites using PEDOT:PSS

A large amount of research within organic biosensors is dominated by organic electrochemical transistors (OECTs) that use conducting polymers such as poly(3,4-ethylene dioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS). Despite the recent advances in OECT-based biosensors, the sensing is solely reliant on the amperometric detection of the bioanalytes. This is typically accompanied by large undesirable parasitic electrical signals from the electroactive components in the electrolyte. Herein, we present the use of in situ resonance Raman spectroscopy to probe subtle molecular structural changes of PEDOT:PSS associated with its doping level. We demonstrate how such doping level changes of PEDOT:PSS can be used, for the first time, on operational OECTs for sensitive and selective metabolite sensing while simultaneously performing amperometric detection of the analyte. We test the sensitivity by molecularly sensing a lowest glucose concentration of 0.02 mM in phosphate-buffered saline solution. By changing the electrolyte to cell culture media, the selectivity of in situ resonance Raman spectroscopy is emphasized as it remains unaffected by other electroactive components in the electrolyte. The application of this molecular structural probe highlights the importance of developing biosensing probes that benefit from high sensitivity of the material's structural and electrical properties while being complimentary with the electronic methods of detection.