The T cell antigen receptor complex expressed on normal peripheral blood CD4-, CD8- T lymphocytes. A CD3-associated disulfide-linked gamma chain heterodimer.

IL-2-dependent cell lines were established from normal peripheral blood T lymphocytes that express neither CD4 nor CD8 differentiation antigens. CD3+,4-,8- cell lines from 15 different donors failed to react with WT31, an mAb directed against the T cell antigen receptor alpha/beta heterodimer. Anti-Leu-4 mAb was used to isolate the CD3/T cell antigen receptor complex from 125I-labeled CD3+,4-,8- (WT31-) T cells. Using detergent conditions that preserved the CD3/T cell antigen receptor complex, an approximately 90 kD disulfide-linked heterodimer, composed of approximately 45- and approximately 40- (or approximately 37-) kD subunits, was coimmunoprecipitated with the invariant 20-29-kD CD3 complex. Analysis of these components by nonequilibrium pH gradient electrophoresis indicated that the approximately 40-kD and approximately 37-kD subunits were similar, and quite distinct from the more basic approximately 45-kD subunit. None of these three subunits reacted with an antibody directed against a beta chain framework epitope. Heteroantiserum against a T cell receptor gamma chain peptide specifically reacted with both the approximately 37- and approximately 40-kD CD3-associated proteins, but not with the approximately 45-kD subunit. CD3+,4-,8- cells failed to transcribe substantial amounts of functional 1.3-kb beta or 1.6-kb alpha mRNA, but produced abundant 1.6-kb gamma mRNA. Southern blot analysis revealed that these CD3+,4-,8- cell lines rearranged both gamma and beta genes, and indicated that the populations were polyclonal. The expression of a CD3-associated disulfide-linked heterodimer on CD3+,4-,8- T cell lines established from normal, adult peripheral blood contrasts with prior reports describing a CD3-associated non-disulfide-linked heterodimer on CD3+/WT31- cell lines established from thymus and peripheral blood obtained from patients with immunodeficiency diseases. We propose that this discrepancy may be explained by preferential usage of the two C gamma genes in T lymphocytes

Experimental study of the dynamics of D+H2 reactive and inelastic collisions below 1.0 eV relative energy

We report the results of state-to-state dynamics experiments on the D + H2 → HD + H reaction as well as D + H2 → H 2 † + D energy transfer at relative energies of 0.67 and 0.79 eV. Both product state distributions and absolute partial cross sections have been determined, from coherent anti-Stokes Raman scattering (CARS) spectra of the HD and H2 † products recorded under single-collision conditions following pulsed-laser photolysis of DI to generate the D atom reactant. At both energies and for both reactive and inelastic collisions there is a strong dynamical bias against rotational and vibrational excitation of the product. However, at 0.67 eV there is an enhancement of both the relative and absolute yield of HD (v′ = 1), and to a lesser extent H2 (v′ = 1), the only energetically accessible vibrationally excited product states. This may be the result of a Feshbach resonance at ≈ 0.65 eV, just above the v′ = 1 threshold energy. Product quantum state distributions from quasiclassical trajectory calculations are in fairly good agreement with the experimental results, except that they do not show the v′ = 1 enhancement at 0.67 eV. However, the partial cross sections from the trajectory calculations are systematically larger than those measured. © 1989 American Institute of Physics.published_or_final_versio

Ising Model Reprogramming of a Repeat Protein's Equilibrium Unfolding Pathway.

Repeat proteins are formed from units of 20-40 aa that stack together into quasi one-dimensional non-globular structures. This modular repetitive construction means that, unlike globular proteins, a repeat protein's equilibrium folding and thus thermodynamic stability can be analysed using linear Ising models. Typically, homozipper Ising models have been used. These treat the repeat protein as a series of identical interacting subunits (the repeated motifs) that couple together to form the folded protein. However, they cannot describe subunits of differing stabilities. Here we show that a more sophisticated heteropolymer Ising model can be constructed and fitted to two new helix deletion series of consensus tetratricopeptide repeat proteins (CTPRs). This analysis, showing an asymmetric spread of stability between helices within CTPR ensembles, coupled with the Ising model's predictive qualities was then used to guide reprogramming of the unfolding pathway of a variant CTPR protein. The designed behaviour was engineered by introducing destabilising mutations that increased the thermodynamic asymmetry within a CTPR ensemble. The asymmetry caused the terminal α-helix to thermodynamically uncouple from the rest of the protein and preferentially unfold. This produced a specific, highly populated stable intermediate with a putative dimerisation interface. As such it is the first step in designing repeat proteins with function regulated by a conformational switch.C.M. is supported by a BBSRC studentship. B.B.S.R.C Grant E005187/1 and QMUL supported this work and J.J.PThis is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.jmb.2016.02.02

Orthopaedic Outreach Program in Uganda: A Strategy to Improve Inequality in Service Delivery between Rural and Urban Communities

Background: Musculoskeletal diseases are on the increase worldwide. Greater than 80% of Ugandans live in rural areas, facing formidable barriers to specialized care. In 1991 the Orthopedics Outreach Program (OOP) was initiated as a plausible solution to the inequity of orthopedic care between the urban and rural disadvantaged populations. This investigation was conducted to evaluate the output, effectiveness, and barriers to access, of the OOP over 13 years.Methods: This was a retrospective analysis to quantify surgical output and effectiveness of the OOP using the outreach record and a cross sectional analysis to assess access and efficacy of the program. Semi-structured and key informant interviews targeted to key actors involved in the OOP were conducted to provide a qualitative assessment of the program.Results: Sixty seven outreach visits were completed, 6,653 patients seen, and 1,071 surgeries performed, at a total cost of US$12,701.00. The cost per patient seen was US$1.91 and US$11.86 per surgery performed. Poverty was uniformly cited as barrier to access, others were, transportation, and lack of awareness. There was unanimous opinion on the worthiness and effectiveness of the OOP, but many operational issues and constraints were cited.Conclusion: The OOP may provide a short and medium term solution to equity and access for orthopedic care in Uganda. There is need to quantify the burden of specific orthopedics conditions. A follow-up analysis assessing operational efficacy and output from 2004 to date, under the African Medical and Research Foundation (AMREF) and Ministry of Health funding is recommended

Increasing dominance of large lianas in Amazonian forests

Ecological orthodoxy suggests that old-growth forests should be close to dynamic equilibrium, but this view has been challenged by recent findings that neotropical forests are accumulating carbon and biomass, possibly in response to the increasing atmospheric concentrations of carbon dioxide. However, it is unclear whether the recent increase in tree biomass has been accompanied by a shift in community composition. Such changes could reduce or enhance the carbon storage potential of old-growth forests in the long term. Here we show that non-fragmented Amazon forests are experiencing a concerted increase in the density, basal area and mean size of woody climbing plants (lianas). Over the last two decades of the twentieth century the dominance of large lianas relative to trees has increased by 1.7–4.6% a year. Lianas enhance tree mortality and suppress tree growth, so their rapid increase implies that the tropical terrestrial carbon sink may shut down sooner than current models suggest. Predictions of future tropical carbon fluxes will need to account for the changing composition and dynamics of supposedly undisturbed forests

Necromass in forests of Madre de Dios, Peru: a comparison between terra firme and lowland forests

Stocks of dead wood or necromass represent an important portion of biomass and nutrients in tropical forests. The objectives of this study were: 1) to evaluate and compare the necromass of "terra firme" and lowlands forests, (2) to study the relationship between necromass, above-ground biomass and wood density, and (3) to estimate the necromass of the department of Madre de Dios, Peru. Stocks of necromass and above-ground biomass were estimated at three different locations using permanent plots and line intercept transects. The average volume of necromass for the three sites was 72.9 m3 ha-1 with an average weight varying between 24.8 and 30.7 Mg ha-1, depending on the estimations of dead wood density used for the calculations. Terra firme forests had significantly higher stocks of necromass than lowland forests. The amount of necromass was 11% of the total above-ground biomass in Madre de Dios forests. The total stock of carbon stored in dead wood for the entire department of Madre de Dios was estimated to be approximately 100 mega tonnes of carbon. This is ten times more than the annual fossil fuel emissions of Peru between 2000 and 2008. The substantial stocks of necromass emphasize the importance of these types of field studies, considering that this component of tropical forest carbon cannot be detected using other methods such as satellite remote sensing

Can the Shape of Nanoparticles Enable the Targeting to Cancer Cells over Healthy Cells?

Macropinocytosis is a consequence of oncogenic alterations of cancer cells while most healthy cells are non-macropinocytic. It is currently unclear whether macropinocytic cancer cells can be targeted rather than healthy cells, by adjusting the shape and size of nanoparticles. Herein, the endocytosis of two differently shaped nanoparticles; nanorods and nanospheres are compared in cancer and healthy cells. The cells are breast epithelial cancer cells (MCF7) and breast epithelial healthy cells (MCF10A) and pancreas cancer cells (PANC-1 cells) and non-tumourogenic patient-derived cancer-associated fibroblasts (CAFs). The endocytosis pathway is quantified by a combination of pair correlation microscopy and endocytosis inhibitors. MCF7 cells use clathrin-mediated endocytosis and macropinocytosis to take up the nanorods while MCF10A cells use predominantly clathrin-mediated endocytosis. Based on the comparison of endocytic behavior of cancer and healthy cells, MCF7 cells can be induced to take up more nanorods and suppress the metabolism and endocytosis of nanorods in MCF10A cells. The nanorods allow targeting to breast cancer MCF7 cells and pancreas cancer cells over the healthy cells. This study opens exciting possibilities for shape to target the cancer cells over healthy cells, by adjusting nanoparticle shape

Necromass in forests of Madre de Dios, Peru: A comparison between terra firme and lowland forests

This is the final version of the article. Available from Universidad Nacional Mayor de San Marcos, Facultad de Ciencias Biológicas via the DOI in this record.Stocks of dead wood or necromass represent an important portion of biomass and nutrients in tropical forests. The objectives of this study were: 1) to evaluate and compare the necromass of “terra firme” and lowlands forests, (2) to study the relationship between necromass, above-ground biomass and wood density, and (3) to estimate the necromass of the department of Madre de Dios, Peru. Stocks of necromass and above-ground biomass were estimated at three different locations using permanent plots and line intercept transects. The average volume of necromass for the three sites was 72.9 m3 ha-1 with an average weight varying between 24.8 and 30.7 Mg ha-1, depending on the estimations of dead wood density used for the calculations. Terra firme forests had significantly higher stocks of necromass than lowland forests. The amount of necromass was 11% of the total above-ground biomass in Madre de Dios forests. The total stock of carbon stored in dead wood for the entire department of Madre de Dios was estimated to be approximately 100 mega tonnes of carbon. This is ten times more than the annual fossil fuel emissions of Peru between 2000 and 2008. The substantial stocks of necromass emphasize the importance of these types of field studies, considering that this component of tropical forest carbon cannot be detected using other methods such as satellite remote sensing

Transient Structural Dynamics of Glycogen Phosphorylase from Nonequilibrium Hydrogen/Deuterium-Exchange Mass Spectrometry

This is the final version. Available on open access from the American Chemical Society via the DOI in this recordData Availability: The authors declare that the data supporting the findings of this study are available in this paper and its Supporting Information files. All additional data is available upon reasonable request. Source data are provided with this paper.It remains a major challenge to ascertain the specific structurally dynamic changes that underpin protein functional switching. There is a growing need in molecular biology and drug discovery to complement structural models with the ability to determine the dynamic structural changes that occur as these proteins are regulated and function. The archetypal allosteric enzyme glycogen phosphorylase is a clinical target of great interest to treat type II diabetes and metastatic cancers. Here, we developed a time-resolved nonequilibrium millisecond hydrogen/deuterium-exchange mass spectrometry (HDX-MS) approach capable of precisely locating dynamic structural changes during allosteric activation and inhibition of glycogen phosphorylase. We resolved obligate transient changes in the localized structure that are absent when directly comparing active/inactive states of the enzyme and show that they are common to allosteric activation by AMP and inhibition by caffeine, operating at different sites. This indicates that opposing allosteric regulation by inhibitor and activator ligands is mediated by pathways that intersect with a common structurally dynamic motif. This mass spectrometry approach uniquely stands to discover local transient structural dynamics and could be used broadly to identify features that influence the structural transitions of proteins.UKRIBiotechnology and Biological Sciences Research Council (BBSRC