Photoaffinity cross-linking of F1ATPase from spinach chloroplasts by 3''-arylazido-β-alanyl-8-azido ATP

UV irradiation of the ATPase (CF₁) from spinach chloroplasts in the presence of 3'-arylazido-β-alanyl-8-azido ATP (8,3'-DiN₃ATP) results in a nucleotide-dependent inactivation of the enzyme and in a nucleotide-dependent formation of -β cross-links. The results demonstrate an interfacial localization of the nucleotide binding sites on CF₁.     

Delayed striate cortical activation during spatial attention

Recordings of event-related potentials (ERPs) and event-related magnetic fields (ERMFs) were combined with functional magnetic resonance imaging (fMRI) to study visual cortical activity in humans during spatial attention. While subjects attended selectively to stimulus arrays in one visual field, fMRI revealed stimulus-related activations in the contralateral primary visual cortex and in multiple extrastriate areas. ERP and ERMF recordings showed that attention did not affect the initial evoked response at 60-90 ms poststimulus that was localized to primary cortex, but a similarly localized late response at 140-250 ms was enhanced to attended stimuli. These findings provide evidence that the primary visual cortex participates in the selective processing of attended stimuli by means of delayed feedback from higher visual-cortical areas.     

High Prevalence and High Incidence of Coinfection with Hepatitis B,Hepatitis C,and Syphilis and Low Rate of Effective Vaccination against Hepatitis B in HIV-Positive Men Who Have Sex with Men with Known Date of HIV Seroconversion in Germany

Objectives

Men who have sex with men (MSM) are at higher risk for coinfection with hepatitis B virus (HBV), hepatitis C virus (HCV), and syphilis than the general population. HIV infection and these coinfections accelerate disease progression reciprocally. This study evaluated the prevalence and incidence of these coinfections in HIV1-positive MSM in Germany.

Materials and Methods

As part of a nationwide, multicenter, prospective cohort study of HIV-infected MSM, plasma samples collected yearly were screened for HBsAg and antibodies to HBc, HBs, HCV, and syphilis. Samples with indications of active HBV or HCV infection were confirmed by polymerase chain reaction. Prevalence and incidence of each infection and incidence rates per study participant were calculated, and incidences over 4-year time intervals compared.

Results

This study screened 5,445 samples from 1,843 MSM. Median age at HIV seroconversion was 33 years. Prevalences of active, cleared, and occult HBV, and of active/cleared HCV were 1.7%, 27.1%, 0.2%, and 8.2%, respectively, and 47.5% had been effectively vaccinated against HBV. Prevalence of antibodies to Treponema pallidum and of triple or quadruple sexually transmitted infections (STIs) were 39.6% and 18.9%, respectively. Prevalence of STI, cleared HBV, HBV vaccination, and history of syphilis differed significantly among age groups. Incidences of HBV, HCV, and syphilis were 2.51, 1.54, and 4.06 per 100 person-years, respectively. Incidences of HCV and syphilis increased over time. HCV incidence was significantly higher in MSM coinfected with syphilis and living in Berlin, and syphilis incidence was significantly higher for MSM living in Berlin.

Discussion

Despite extensive HBV vaccination campaigns, fewer than 50% of screened MSM were effectively vaccinated, with a high proportion of HIV-positive MSM coinfected with HBV. High rates of STI coinfections in HIV-positive MSM and increasing incidences emphasize the need for better tailored campaigns for HBV vaccination and STI prevention.     

Entrainment of Human Alpha Oscillations Selectively Enhances Visual Conjunction Search

The functional role of the alpha-rhythm which dominates the human electroencephalogram (EEG) is unclear. It has been related to visual processing, attentional selection and object coherence, respectively. Here we tested the interaction of alpha oscillations of the human brain with visual search tasks that differed in their attentional demands (pre-attentive vs. attentive) and also in the necessity to establish object coherence (conjunction vs. single feature). Between pre- and post-assessment elderly subjects received 20 min/d of repetitive transcranial alternating current stimulation (tACS) over the occipital cortex adjusted to their individual alpha frequency over five consecutive days. Compared to sham the entrained alpha oscillations led to a selective, set size independent improvement in the conjunction search task performance but not in the easy or in the hard feature search task. These findings suggest that cortical alpha oscillations play a specific role in establishing object coherence through suppression of distracting objects.     

Effects of cyclosporine A and its immunosuppressive or non-immunosuppressive derivatives [D-Ser]8-CsA and Cs9 on mitochondria from different brain regions

We studied the functional properties of isolated brain mitochondria (BM) prepared from total rat brain (BM(total)) or from cerebral subregions under basal and Ca(2+) overload conditions in order to evaluate the effects of cyclosporine A (CsA) in a regiospecific manner. CsA-induced effects were compared with those of two derivatives-the none-immunosuppressive [O-(NH(2)(CH2)(5)NHC(O)CH(2))-D-Ser](8)-CsA (Cs9) and its congener, the immunosuppressive [D-Ser](8)-CsA. The glutamate/malate-dependent state 3 respiration of mitochondria (state 3(glu/mal)) differed in region-specific manner (cortex > striatum = cerebellum > substantia nigra > hippocampus), but was significantly increased by 1μM CsA (+21±5%) in all regions. Ca(2+) overload induced by addition of 20μM Ca(2+) caused a significant decrease of state 3(glu/mal) (-45 to -55%) which was almost completely prevented in the presence of 1μM CsA, 1μM Cs9 or 1μM [D-Ser](8)-CsA. Mitochondrial Ca(2+) accumulation thresholds linked to permeability transition (PT) as well as the rate and completeness of mitochondrial Ca(2+) accumulation differed between different brain regions. For the first time, we provide a detailed, regiospecific analysis of Ca(2+)-dependent properties of brain mitochondria. Regardless of their immunosuppressive impact, CsA and its analogues improved mitochondrial functional properties under control conditions. They also preserved brain mitochondria against Ca(2+) overload-mediated PT and functional impairments. Since Cs9 does not mediate immunosuppression, it might be used as a more specific PT inhibitor than CsA.     

Kidney pathology precedes and predicts the pathological cascade of cerebrovascular lesions in stroke prone rats

Introduction

Human cerebral small vessel disease (CSVD) has been hypothesized to be an age-dependent disease accompanied by similar vascular changes in other organs. SHRSP feature numerous vascular risk factors and may be a valid model of some aspects of human CSVD. Here we compare renal histopathological changes with the brain pathology of spontaneously hypertensive stroke-prone rats (SHRSP).

Material and Methods

We histologically investigated the brains and kidneys of 61 SHRSP at different stages of age (12 to 44 weeks). The brain pathology (aggregated erythrocytes in capillaries and arterioles, microbleeds, microthromboses) and the kidney pathology (aggregated erythrocytes within peritubular capillaries, tubular protein cylinders, glomerulosclerosis) were quantified separately. The prediction of the brain pathology by the kidney pathology was assessed by creating ROC-curves integrating the degree of kidney pathology and age of SHRSP.

Results

Both, brain and kidney pathology, show an age-dependency and proceed in definite stages whereas an aggregation of erythrocytes in capillaries and arterioles, we parsimoniously interpreted as stases, represent the initial finding in both organs. Thus, early renal tubulointerstitial damage characterized by rather few intravasal erythrocyte aggregations and tubular protein cylinders predicts the initial step of SHRSPs'' cerebral vascular pathology marked by accumulated erythrocytes. The combined increase of intravasal erythrocyte aggregations and protein cylinders accompanied by glomerulosclerosis and thrombotic renal microangiopathy in kidneys of older SHRSP predicts the final stages of SHRSPs'' cerebrovascular lesions marked by microbleeds and thrombotic infarcts.

Conclusion

Our results illustrate a close association between structural brain and kidney pathology and support the concept of small vessel disease to be an age-dependent systemic pathology. Further, an improved joined nephrologic and neurologic diagnostic may help to identify patients with CSVD at an early stage.     

Evaluation of two human plasma pools as candidate international standard preparations for syphilitic antibodies

A collaborative study was designed to asses two freeze-dried human plasma preparations containing anti-Treponema pallidum antibodies, 05/132 and 05/122, for their suitability as international reference reagents for syphilis serology. Both preparations are intended as replacements of the first international standard (IS) for syphilitic serum antibodies (HS). Samples were tested by eight laboratories using the T. pallidum passive particle agglutination assay (TPPA), the venereal disease research laboratory test (VDRL) and the rapid plasma reagin test (RPR). In addition a range of immunoassays was also used. The outcome of the collaborative study revealed that candidate standard 05/132 contains T. pallidum-specific IgG and IgM and is reactive in VDRL or RPR, and that 05/122 contains T. pallidum-specific IgG but is not reactive in either the VDRL or RPR test. Both 05/132 and 05/122 are reactive in the TPPA. On the basis of these results the Expert Committee on Biological Standardization of the World Health Organization designated 05/132 as the 1st IS for human syphilitic plasma IgG and IgM with a unitage of 3 IU per ampoule relative to HS and 05/122 as the 1st IS for human syphilitic plasma IgG with a unitage of 300 mIU per ampoule relative to 05/132.     

Alien hand syndrome: neural correlates of movements without conscious will

Background

The alien hand syndrome is a striking phenomenon characterized by purposeful and autonomous movements that are not voluntarily initiated. This study aimed to examine neural correlates of this rare neurological disorder in a patient with corticobasal degeneration and alien hand syndrome of the left hand.

Methodology/Principal Findings

We employed functional magnetic resonance imaging to investigate brain responses associated with unwanted movements in a case study. Results revealed that alien hand movements involved a network of brain activations including the primary motor cortex, premotor cortex, precuneus, and right inferior frontal gyrus. Conscious and voluntary movements of the alien hand elicited a similar network of brain responses but lacked an activation of the inferior frontal gyrus. The results demonstrate that alien and unwanted movements may engage similar brain networks than voluntary movements, but also imply different functional contributions of prefrontal areas. Since the inferior frontal gyrus was uniquely activated during alien movements, the results provide further support for a specific role of this brain region in inhibitory control over involuntary motor responses.

Conclusions/Significance

We discuss the outcome of this study as providing evidence for a distributed neural network associated with unwanted movements in alien hand syndrome, including brain regions known to be related to movement execution and planning as well as areas that have been linked to inhibition control (inferior frontal gyrus) and experience of agency (precuneus).     

Cloning, purification, and nucleotide-binding traits of the catalytic subunit A of the V1VO ATPase from Aedes albopictus

The Asian tiger mosquito, Aedes albopictus, is commonly infected by the gregarine parasite Ascogregarina taiwanensis, which develops extracellularly in the midgut of infected larvae. The intracellular trophozoites are usually confined within a parasitophorous vacuole, whose acidification is generated and controlled by the V(1)V(O) ATPase. This proton pump is driven by ATP hydrolysis, catalyzed inside the major subunit A. The subunit A encoding gene of the Aedes albopictus V(1)V(O) ATPase was cloned in pET9d1-His(3) and the recombinant protein, expressed in the Escherichia coli Rosetta 2 (DE3) strain, purified by immobilized metal affinity- and ion-exchange chromatography. The purified protein was soluble and properly folded. Analysis of secondary structure by circular dichroism spectroscopy showed that subunit A comprises 43% alpha-helix, 25% beta-sheet and 40% random coil content. The ability of subunit A of eukaryotic V-ATPases to bind ATP and/or ADP is demonstrated by photoaffinity labeling and fluorescence correlation spectroscopy (FCS). Quantitation of the FCS data indicates that the ADP-analogues bind slightly weaker to subunit A than the ATP-analogues. Tryptophan fluorescence quenching of subunit A after binding of different nucleotides provides evidence for secondary structural alterations in this subunit caused by nucleotide-binding.