A cyclic undecamer peptide mimics a turn in folded Alzheimer amyloid β and elicits antibodies against oligomeric and fibrillar amyloid and plaques

The 39- to 42-residue amyloid β (Aβ) peptide is deposited in extracellular fibrillar plaques in the brain of patients suffering from Alzheimer's Disease (AD). Vaccination with these peptides seems to be a promising approach to reduce the plaque load but results in a dominant antibody response directed against the N-terminus. Antibodies against the N-terminus will capture Aβ immediately after normal physiological processing of the amyloid precursor protein and therefore will also reduce the levels of non-misfolded Aβ, which might have a physiologically relevant function. Therefore, we have targeted an immune response on a conformational neo-epitope in misfolded amyloid that is formed in advance of Aβ-aggregation. A tetanus toxoid-conjugate of the 11-meric cyclic peptide Aβ(22-28)-YNGK' elicited specific antibodies in Balb/c mice. These antibodies bound strongly to the homologous cyclic peptide-bovine serum albumin conjugate, but not to the homologous linear peptide-conjugate, as detected in vitro by enzyme-linked immunosorbent assay. The antibodies also bound--although more weakly--to Aβ(1-42) oligomers as well as fibrils in this assay. Finally, the antibodies recognized Aβ deposits in AD mouse and human brain tissue as established by immunohistological staining. We propose that the cyclic peptide conjugate might provide a lead towards a vaccine that could be administered before the onset of AD symptoms. Further investigation of this hypothesis requires immunization of transgenic AD model mice.     

Cost effectiveness analysis of clinically driven versus routine laboratory monitoring of antiretroviral therapy in Uganda and Zimbabwe

Background

Despite funding constraints for treatment programmes in Africa, the costs and economic consequences of routine laboratory monitoring for efficacy and toxicity of antiretroviral therapy (ART) have rarely been evaluated.

Methods

Cost-effectiveness analysis was conducted in the DART trial (ISRCTN13968779). Adults in Uganda/Zimbabwe starting ART were randomised to clinically-driven monitoring (CDM) or laboratory and clinical monitoring (LCM); individual patient data on healthcare resource utilisation and outcomes were valued with primary economic costs and utilities. Total costs of first/second-line ART, routine 12-weekly CD4 and biochemistry/haematology tests, additional diagnostic investigations, clinic visits, concomitant medications and hospitalisations were considered from the public healthcare sector perspective. A Markov model was used to extrapolate costs and benefits 20 years beyond the trial.

Results

3316 (1660LCM;1656CDM) symptomatic, immunosuppressed ART-naive adults (median (IQR) age 37 (32,42); CD4 86 (31,139) cells/mm³) were followed for median 4.9 years. LCM had a mean 0.112 year (41 days) survival benefit at an additional mean cost of $765 [95%CI:685,845], translating into an adjusted incremental cost of $7386 [3277,dominated] per life-year gained and $7793 [4442,39179] per quality-adjusted life year gained. Routine toxicity tests were prominent cost-drivers and had no benefit. With 12-weekly CD4 monitoring from year 2 on ART, low-cost second-line ART, but without toxicity monitoring, CD4 test costs need to fall below $3.78 to become cost-effective (<3xper-capita GDP, following WHO benchmarks). CD4 monitoring at current costs as undertaken in DART was not cost-effective in the long-term.

Conclusions

There is no rationale for routine toxicity monitoring, which did not affect outcomes and was costly. Even though beneficial, there is little justification for routine 12-weekly CD4 monitoring of ART at current test costs in low-income African countries. CD4 monitoring, restricted to the second year on ART onwards, could be cost-effective with lower cost second-line therapy and development of a cheaper, ideally point-of-care, CD4 test.     

Cognitive Dysfunction among HIV Positive and HIV Negative Patients with Psychosis in Uganda

Background

Cognitive impairment is an established phenomenon in HIV infected individuals and patients that have psychosis. However there is need to establish the severity of the impairment if patients are co morbid with both conditions.

Aim

To compare cognitive function among HIV positive individuals and HIV negative individuals with psychosis.

Methods

We recruited patients with psychosis at two national referral hospitals. A standardized demographics questionnaire and psychiatric, physical, and laboratory assessments were conducted. Types of psychosis were diagnosed using the Mini International Neuropsychiatric Inventory-PLUS while cognitive functioning was determined using the Mini mental state examination (MMSE) and a neuropsychological test battery. Follow-up assessments on cognitive function and severity of psychiatric illness were performed at 3 and 6 months. Pairwise comparison and multivariable logistic regression analysis were used to determine the differences between the HIV positive and HIV negative individuals.

Results

There were 156 HIV positive and 322 HIV negative participants. The mean age was 33 years for the HIV positive group and 29 years for the HIV negative group (p<0.001). The HIV positive individuals were almost three times (OR = 2.62 CI 95% 1.69–4.06) more likely to be cognitively impaired on the MMSE as well as the following cognitive tests:- WHO-UCLA Auditory Verbal Learning Test (OR 1.79, 95% CI 1.09–2.92), Verbal Fluency (OR 3.42, 95% CI 2.24–5.24), Color Trails 1 (OR 2.03, 95% CI 1.29–3.02) and Color Trails 2 (OR 3.50 95% 2.00–6.10) all p = 0.01. There was improvement in cognitive function at follow up; however the impairment remained higher for the HIV positive group (p<0.001).

Conclusion

Cognitive impairment in psychosis was worsened by HIV infection. Care plans to minimize the effect of this impairment should be structured for the management of individuals with HIV and psychosis.     

Inhibition of protein kinase B activity induces cell cycle arrest and apoptosis during early G₁ phase in CHO cells

Inhibition of PKB (protein kinase B) activity using a highly selective PKB inhibitor resulted in inhibition of cell cycle progression only if cells were in early G1 phase at the time of addition of the inhibitor, as demonstrated by time-lapse cinematography. Addition of the inhibitor during mitosis up to 2 h after mitosis resulted in arrest of the cells in early G1 phase, as deduced from the expression of cyclins D and A and incorporation of thymidine. After 24 h of cell cycle arrest, cells expressed the cleaved caspase-3, a central mediator of apoptosis. These results demonstrate that PKB activity in early G1 phase is required to prevent the induction of apoptosis. Using antibodies, it was demonstrated that active PKB translocates to the nucleus during early G1 phase, while an even distribution of PKB was observed through cytoplasm and nucleus during the end of G1 phase.     

Regeneration: The ultimate example of wound healing

The outcome of wound repair in mammals is often characterized by fibrotic scaring. Vertebrates such as zebrafish, frogs, and salamanders not only heal scarlessly, but also can regenerate lost appendages. Decades of study on the process of animal regeneration has produced key insights into the mechanisms of how complex tissue is restored. By examining our current knowledge of regeneration, we can draw parallels with mammalian wound healing to identify the molecular determinants that produce such differing outcomes.     

Reproductive isolation in the saltans group of Drosophila. I. The saltans subgroup

In order to study isolation within the salians subgroup, pair mating crosses involving its 7 species were performed. The results of testing different interspecific combinations varied from complete isolation at the insemination level to the production of fertile hybrids. Some isolation indices are proposed: Ii (isolation index at the insemination level), Fi (isolation index at the fertilization level), Ti (total isolation index), and Ai (average isolation index). A schema of the biological relationships on the basis of the isolation degree is also presented for the 7 species of the subgroup.Part of this study was included in the thesis submitted for the PH.D. degree at the University of São Paulo and was performed during the tenure of a fellowship supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo.     

Fluorescence stopped-flow study of the o-phthaldialdehyde reaction

The fluorogenic reaction involving three species, namely, a primary amine, o-phthaldialdehyde (OPA), and a thiol compound was studied with the fluorescence stopped-flow technique. The results are consistent with the reaction of the amine with a 1:1 adduct of OPA and the thiol compound. The equilibrium constant for the formation of the adduct, OPAME, from OPA and mercaptoethanol (ME) was determined to be 164 m^?1. A survey of the rates of reaction of OPAME with various amino acids demonstrated that with OPA: ME:amine equal to 1:2.4:1 (total OPA concentration 0.5 to 3.0 × 10^?3m), the reaction followed second-order kinetics, with k = 150 to 450 m^?1s^?1 at pH 9.O. The differences in rates are discussed in relation to structural differences between the amines. The reaction, when conducted under conditions of excess OPAME yielded pseudo-first-order kinetics, with rates consistent with the second-order rate constants. The rate of reaction of OPAME with alanine was maximal at pH 10.5–11, and a great excess of ME resulted in a slower rate. Slower rates were also observed if ME was replaced by dithiothreitol or 1-propanethiol.     

Linking ultrastructure and function in four genera of anaerobic ammonium-oxidizing bacteria: cell plan, glycogen storage, and localization of cytochrome C proteins

Anaerobic ammonium oxidation (anammox) is an ecologically and industrially important process and is performed by a clade of deeply branching Planctomycetes. Anammox bacteria possess an intracytoplasmic membrane-bounded organelle, the anammoxosome. In the present study, the ultrastructures of four different genera of anammox bacteria were compared with transmission electron microscopy and electron tomography. The four anammox genera shared a common cell plan and contained glycogen granules. Differences between the four genera included cell size (from 800 to 1,100 nm in diameter), presence or absence of cytoplasmic particles, and presence or absence of pilus-like appendages. Furthermore, cytochrome c proteins were detected exclusively inside the anammoxosome. This detection provides further support for the hypothesis that this organelle is the locus of anammox catabolism.     

Spatial population structure of a specialist leaf-mining moth

1. The spatial structure of natural populations may profoundly influence their dynamics. Depending on the frequency of movements among local populations and the consequent balance between local and regional population processes, earlier work has attempted to classify metapopulations into clear-cut categories, ranging from patchy populations to sets of remnant populations. In an alternative, dichotomous scheme, local populations have been classified as self-sustaining populations generating a surplus of individuals (sources) and those depending on immigration for persistence (sinks). 2. In this paper, we describe the spatial population structure of the leaf-mining moth Tischeria ekebladella, a specialist herbivore of the pedunculate oak Quercus robur. We relate moth dispersal to the distribution of oaks on Wattkast, a small island (5 km(2)) off the south-western coast of Finland. 3. We build a spatially realistic metapopulation model derived from assumptions concerning the behaviour of individual moths, and show that the model is able to explain part of the variation in observed patterns of occurrence and colonization. 4. While the species was always present on large trees, a considerable proportion of the local populations associated with small oaks showed extinction-recolonization dynamics. The vast majority of moth individuals occur on large trees. 5. According to model predictions, the dominance of local vs. regional processes in tree-specific moth dynamics varies drastically across the landscape. Most local populations may be defined broadly as 'sinks', as model simulations suggest that in the absence of immigration, only the largest oaks will sustain viable moth populations. Large trees in areas of high oak density will contribute most to the overall persistence of the metapopulation by acting as sources of moths colonizing other trees. 6. No single 'metapopulation type' will suffice to describe the oak-moth system. Instead, our study supports the notion that real populations are often a mix of earlier identified categories. The level to which local populations may persist after landscape modification will vary across the landscape, and sweeping classifications of metapopulations into single categories will contribute little to understanding how individual local populations contribute to the overall persistence of the system.