Homoleptic complexes of isocyano- and diisocyanobiazulenes with a 12-electron, ligand-based redox capacity.

Oligo- and polyazulenes are attractive π-conjugated building blocks in designing advanced functional materials. Herein, we demonstrate that anchoring one or both isocyanide termini of the redox non-innocent 2,2'-diisocyano-6,6'-biazulenic π-linker (1) to the redox-active [Cr(CO)5] moiety provided a convenient intramolecular redox reference for unambiguously establishing that the 6,6'-biazulenic scaffold undergoes a reversible one-step 2e- reduction governed by reduction potential compression/inversion. Treatment of bis(η6-naphthalene)chromium(0) with six equiv. of 2-isocyano-1,1',3,3'-tetraethoxycarbonyl-6,6'-biazulene (6) or [(OC)5Cr(η1-2,2'-diisocyano-1,1',3,3'-tetraethoxycarbonyl-6,6'-biazulene)] (11) afforded homoleptic Cr(0) complexes 13 and 14 with a 12e- (per molecule) ligand-based reduction capacity at mild E1/2 of -1.29 V and -1.15 V vs. Cp2Fe0/+, respectively. The overall reversible redox capacity varies from 15e- for the mononuclear complex 13 to 21e- for the heptanuclear complex 14. The latter "nanocomplex" has a diameter of ca. 5 nm and features seven Cr(0) centers interlinked with six 2,2'-diisocyano-6,6'-biazulenic bridges. The X-ray structure of [(OC)5Cr(2-isocyano-1,1',3,3'-tetraethoxycarbonyl-6,6'-biazulene)] (7) indicated a 43.5° interplanar angle between the two azulenic moieties. Self-assembly of 11 on a Au(111) substrate afforded an organometallic monolayer film of 11 featuring approximately upright orientation of the 2,2'-diisocyano-6,6'-biazulenic linkers, as evidenced by ellipsometric measurements and the RAIR signature of the C4v-symmetric [(-NC)Cr(CO)5] infrared reporter within 11. Remarkably, comparing the FTIR spectrum of 11 in solution with the RAIR spectrum of 11 adsorbed on Au(111) suggested electronic coupling at a ca. 2 nm distance between the Cr(0) and Au atoms linked by the 2,2'-diisocyano-6,6'-biazulene bridge.

A kinase-independent function of cyclin-dependent kinase 6 promotes outer radial glia expansion and neocortical folding.

The neocortex, the center for higher brain function, first emerged in mammals and has become massively expanded and folded in humans, constituting almost half the volume of the human brain. Primary microcephaly, a developmental disorder in which the brain is smaller than normal at birth, results mainly from there being fewer neurons in the neocortex because of defects in neural progenitor cells (NPCs). Outer radial glia (oRGs), NPCs that are abundant in gyrencephalic species but rare in lissencephalic species, are thought to play key roles in the expansion and folding of the neocortex. However, how oRGs expand, whether they are necessary for neocortical folding, and whether defects in oRGs cause microcephaly remain important questions in the study of brain development, evolution, and disease. Here, we show that oRG expansion in mice, ferrets, and human cerebral organoids requires cyclin-dependent kinase 6 (CDK6), the mutation of which causes primary microcephaly via an unknown mechanism. In a mouse model in which increased Hedgehog signaling expands oRGs and intermediate progenitor cells and induces neocortical folding, CDK6 loss selectively decreased oRGs and abolished neocortical folding. Remarkably, this function of CDK6 in oRG expansion did not require its kinase activity, was not shared by the highly similar CDK4 and CDK2, and was disrupted by the mutation causing microcephaly. Therefore, our results indicate that CDK6 is conserved to promote oRG expansion, that oRGs are necessary for neocortical folding, and that defects in oRG expansion may cause primary microcephaly.

Recent drug discovery success signals renaissance in biophysics.

With a scope that spans the hierarchy of biological organization from molecules and cells to organisms and populations, the discipline of biophysics has been proven to be particularly well suited for connecting the molecular embodiments of human diseases to the medical conditions experienced by patients. Recently, fundamental biophysical research on aberrant proteins involved in maintaining salt and water balance in our lungs, oxygen transport from our lungs to the rest of the body, and the pumping of blood by our hearts have been successfully translated to the creation of transformational new medicines that are radically changing the lives of patients. With these and other emerging discoveries, the field of applied biophysics is experiencing the beginnings of a veritable renaissance era.

Another look at the eigenvalues of a population matrix model.

Population matrix models are important tools in resource management, in part because they are used to calculate the finite rate of growth ("dominant eigenvalue"). But understanding how a population matrix model converts life history traits into the finite rate of growth can be tricky. We introduce interactive software ("IsoPOPd") that uses the characteristic equation to display how vital rates (survival and fertility) contribute to the finite rate of growth. Higher-order interactions among vital rates complicate the linkage between a management intervention and a population's growth rate. We illustrate the use of the software for investigating the consequences of three management interventions in a 3-stage model of white-tailed deer (Odocoileus virginianus). The software is applicable to any species with 2- or 3-stages, but the mathematical concepts underlying the software are applicable to a population matrix model of any size. The IsoPOPd software is available at: https://cwhl.vet.cornell.edu/tools/isopopd.

The potency-insolubility conundrum in pharmaceuticals: Mechanism and solution for hepatitis C protease inhibitors.

As compounds are optimized for greater potency during pharmaceutical discovery, their aqueous solubility often decreases, making them less viable as orally-administered drugs. To investigate whether potency and insolubility share a common origin, we examined the structural and thermodynamic properties of telaprevir, a sparingly soluble inhibitor of hepatitis C virus protease. Comparison of the hydrogen bond motifs in crystalline telaprevir with those present in the protease-telaprevir complex revealed striking similarities. Additionally, the thermodynamics of telaprevir dissolution closely resembles those of protein-ligand dissociation. Together, these findings point to a common origin of potency and insolubility rooted in particular amide-amide hydrogen bond patterns. The insolubility of telaprevir is shown by computational analysis to be caused by interactions in the crystal, not unfavorable hydrophobic hydration. Accordingly, competing out the particular amide-amide hydrogen bond motifs in crystalline telaprevir with 4-hydroxybenzoic acid yielded a co-crystalline solid with excellent aqueous dissolution and oral absorption. The analysis suggests a generalizable approach for identifying drug candidate compounds that either can or cannot be rendered orally bioavailable by alteration of their crystalline solid phases, in an approach that provides a pragmatic way to attain substantial enhancements in the success rate of drug discovery and development.

Getting physical to fix pharma.

Powerful technologies allow the synthesis and testing of large numbers of new compounds, but the failure rate of pharmaceutical R&D remains very high. Greater understanding of the fundamental physical chemical behaviour of molecules could be the key to greatly enhancing the success rate of drug discovery.

Predictive and prognostic angiogenic markers in a gynecologic oncology group phase II trial of bevacizumab in recurrent and persistent ovarian or peritoneal cancer.

OBJECTIVE: Potential predictive/prognostic angiogenic markers were prospectively examined in a phase II trial of bevacizumab in epithelial ovarian cancer (EOC)/primary peritoneal cancer (PPC). METHODS: Recurrent/persistent EOC/PPC patients were treated with bevacizumab (15 mg/kg IV q21days) until disease progression. Validated-immunohistochemistry (IHC) assays were performed on pre-cycle 1/4 tumor biopsies for CD31-microvessel density (MVD), VEGF-histoscore (HS), p53-HS, and TSP1 image analysis score (IA). Pre-cycle 1/4 serum and plasma VEGF were quantified using a validated-ELISA. RESULTS: CD31-MVD and serum VEGF, evaluated pre-cycle 1 in 41/61 and 51/61 eligible patients, respectively, did not appear to be correlated. High CD31-MVD, categorized at the median, appeared to be associated with tumor response, a 13-month shorter median survival, and an increased risk of death (unadjusted hazard ratio [HR] = 2.2, 95% confidence interval [CI] = 1.067-4.467). In addition, each standard deviation (SD) increase in CD31-MVD appeared to be associated with worse survival in unadjusted and adjusted analyses. IHC and plasma biomarkers did not change with bevacizumab treatment except for serum VEGF, which appeared to decrease during bevacizumab treatment. This decrease was not associated with response. High pre-cycle 1 serum VEGF, categorized at the median, was associated with 22-month shorter median survival and an increased risk of death (unadjusted HR = 2.7, 95% CI = 1.369-5.191). Categorized p53 appeared to be associated with unadjusted survival and each SD increase in TSP1-IA appeared to be associated with a decreased risk of progression in unadjusted and adjusted analyses. CONCLUSIONS: Despite the limitations in sample size and exploratory nature of the study, angiogenic markers in tumor and serum may provide prognostic value in recurrent/persistent EOC/PPC, and are being prospectively evaluated in the GOG phase III trial of carboplatin, paclitaxel and bevacizumab/placebo in previously untreated EOC/PPC.

Evaluation of measurement uncertainties in human diffusion tensor imaging (DTI)-derived parameters and optimization of clinical DTI protocols with a wild bootstrap analysis.

PURPOSE: To quantify measurement uncertainties of fractional anisotropy, mean diffusivity, and principal eigenvector orientations in human diffusion tensor imaging (DTI) data acquired with common clinical protocols using a wild bootstrap analysis, and to establish optimal scan protocols for clinical DTI acquisitions. MATERIALS AND METHODS: A group of 13 healthy volunteers were scanned using three commonly used DTI protocols with similar total scan times. Two important parameters-the number of unique diffusion gradient directions (NUDG) and the ratio of the total number of diffusion-weighted (DW) images to the total number of non-DW images (DTIR)-were analyzed in order to investigate their combined effects on uncertainties of DTI-derived parameters, using results from both the Monte Carlo simulation and the wild bootstrap analysis of uncertainties in human DTI data. RESULTS: The wild bootstrap analysis showed that uncertainties in human DTI data are significantly affected by both NUDG and DTIR in many brain regions. These results agree with previous predictions based on error-propagations as well as results from simulations. CONCLUSION: Our results demonstrate that within a clinically feasible DTI scan time of about 10 minutes, a protocol with number of diffusion gradient directions close to 30 provides nearly optimal measurement results when combined with a ratio of the total number of DW images over non-DW images equal to six. Wild bootstrap can serve as a useful tool to quantify the measurement uncertainty from human DTI data.

An optimized wild bootstrap method for evaluation of measurement uncertainties of DTI-derived parameters in human brain.

Evaluation of measurement uncertainties (or errors) in diffusion tensor-derived parameters is essential to quantify the sensitivity and specificity of these quantities as potential surrogate biomarkers for pathophysiological processes with diffusion tensor imaging (DTI). Computational methods such as the Monte Carlo simulation have provided insights into characterization of the measurement uncertainty in DTI. However, due to the complexity of real brain data as well as different sources of variations during the image acquisition, a robust estimator for DTI measurement uncertainty in human brain is required. Recent studies have shown that wild bootstrap, a novel nonparametric statistical method, can potentially provide effective estimations of DTI measurement uncertainties in human brain DTI data. In this study, we further optimized the DTI application of the wild bootstrap method for typical clinical applications. We evaluated the validity of wild bootstrap utilizing numerical simulations with different combinations of DTI protocol parameters and wild bootstrap experimental designs, and quantitatively compared estimates of uncertainties from wild bootstrapping with those from Monte Carlo simulations. Our results demonstrate that a wild bootstrap implementation using at least 1000 wild bootstrap iterations with a type II or type III heteroskedasticity consistent covariance matrix estimator provides robust evaluations of most DTI protocols.

The private sector and HIV/AIDS in Africa: taking stock of 6 years of applied research.

BACKGROUND: Until recently, little was known about the costs of the HIV/AIDS epidemic to businesses in Africa or about business responses to the epidemic. This paper synthesizes the results of a set of studies conducted between 1999 and 2006. METHODS: Data for the studies included were drawn from human resource, financial, and medical records of 16 large companies and from 7 surveys of small, medium-sized, and large companies in South Africa, Uganda, Kenya, Zambia, Ethiopia, and Rwanda. RESULTS: Estimated workforce HIV prevalence ranged from 5 to 37%. The average cost per employee lost to AIDS varied from 0.5 to 5.6 times the average annual compensation of the employee affected. Labor cost increases were estimated at 0.6-10.8% but exceeded 3% at only two of 14 companies. Antiretroviral treatment at a cost of US$360/patient per year was found to have positive financial returns for most but not all companies. Managers of small and medium-sized enterprises (SME) reported low AIDS-related employee attrition, little concern about the impacts of AIDS, and relatively little interest in taking action. AIDS was estimated to increase the average operating costs of SME by less than 1%. CONCLUSION: For most companies, AIDS is causing a moderate increase in labor costs, with costs determined mainly by HIV prevalence, employee skill level, and employment policies. Treatment of HIV-positive employees is a good investment for many large companies. Small companies have less capacity to respond to workforce illness and little concern about it. Research on the effectiveness of workplace interventions is needed.

Public-private partnerships to build human capacity in low income countries: findings from the Pfizer program.

BACKGROUND: The ability of health organizations in developing countries to expand access to quality services depends in large part on organizational and human capacity. Capacity building includes professional development of staff, as well as efforts to create working environments conducive to high levels of performance. The current study evaluated an approach to public-private partnership where corporate volunteers give technical assistance to improve organizational and staff performance. From 2003 to 2005, the Pfizer Global Health Fellows program sent 72 employees to work with organizations in 19 countries. This evaluation was designed to assess program impact. METHODS: The researchers administered a survey to 60 Fellows and 48 Pfizer Supervisors. In addition, the team conducted over 100 interviews with partner organization staff and other key informants during site visits in Uganda, Kenya, Ghana, South Africa and India, the five countries where 60% of Fellows were placed. RESULTS: Over three-quarters of Fellowships appear to have imparted skills or enhanced operations of NGOs in HIV/AIDS and other health programs. Overall, 79% of Fellows reported meeting all or most technical assistance goals. Partner organization staff reported that the Fellows provided training to clinical and research personnel; strengthened laboratory, pharmacy, financial control, and human resource management systems; and helped expand Partner organization networks. Local staff also reported the Program changed their work habits and attitudes. The evaluation identified problems in defining goals of Fellowships and matching Organizations with Fellows. Capacity building success also appears related to size and sophistication of partner organization. CONCLUSION: Public expectations have grown regarding the role corporations should play in improving health systems in developing countries. Corporate philanthropy programs based on "donations" of personnel can help build the organizational and human capacity of frontline agencies delivering health services. More attention is needed to measure and compare outcomes of international volunteering programs, and to identify appropriate strategies for expansion.

Private sector provision and financing of AIDS treatment in Africa: current developments.

Despite the rapid expansion of public sector highly active antiretroviral (ARV) treatment programs, the private sector continues to be an important source of services and financing for AIDS treatment in Africa. This article reviews currently available information on private sector initiatives, including recent innovations. Private sector providers continue to offer ARV treatment, although adherence problems resulting from high user fees indicate the need for employer, donor, or insurance support. Employer clinics have reported impressive results in patient recruitment and survival. Health insurers are removing AIDS exclusions and expanding AIDS coverage, in some cases with targeted lower cost policies. Public- or donor-funded ARVs have been used to leverage the expansion of populations treated at employer clinics, and attempts are underway to contract for private sector services using public and donor funds. With both funds and clinical resources stretched to meet AIDS treatment goals in countries with a high prevalence of HIV, further efforts are indicated to leverage private sector resources as part of a national treatment plan.

Treatment of HIV/AIDS at South Africa's largest employers: myth and reality.

OBJECTIVES: To determine what proportion of employees at the largest private-sector companies in South Africa have access to HIV/AIDS care and treatment, including antiretroviral therapy (ART); how many employees are enrolled in disease management programmes; how many are receiving ART; and which approach to the financing and delivery of care is proving most successful at reaching eligible employees. DESIGN: All 64 private-sector and parastatal companies with more than 6000 employees in South Africa were identified and contacted. Those that agreed to participate were interviewed by telephone using a structured questionnaire. RESULTS: Fifty-two companies agreed to participate. Among these companies, 63% of employees had access to employer-sponsored care and treatment for HIV/AIDS. However, access varied widely by sector. Approximately 27% of suspected HIV-positive employees were enrolled in disease management programmes, or 4.4% of the workforce overall. Fewer than 4000 employees in the entire sample were receiving ART. In-house (employer) disease management programmes and independent disease management programmes achieved higher uptake of services than did medical aid schemes. CONCLUSIONS: Publicity by large employers about their treatment programmes should be interpreted cautiously. While there is a high level of access to treatment, uptake of services is low and only a small fraction of employees medically eligible for ART are receiving it.

Nucleotide-binding domains of cystic fibrosis transmembrane conductance regulator, an ABC transporter, catalyze adenylate kinase activity but not ATP hydrolysis.

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel in the ATP-binding cassette (ABC) transporter family. CFTR consists of two transmembrane domains, two nucleotide-binding domains (NBD1 and NBD2), and a regulatory domain. Previous biochemical reports suggest NBD1 is a site of stable nucleotide interaction with low ATPase activity, whereas NBD2 is the site of active ATP hydrolysis. It has also been reported that NBD2 additionally possessed adenylate kinase (AK) activity. Knowledge about the intrinsic biochemical activities of the NBDs is essential to understanding the Cl(-) ion gating mechanism. We find that purified mouse NBD1, human NBD1, and human NBD2 function as adenylate kinases but not as ATPases. AK activity is strictly dependent on the addition of the adenosine monophosphate (AMP) substrate. No liberation of [(33)P]phosphate is observed from the gamma-(33)P-labeled ATP substrate in the presence or absence of AMP. AK activity is intrinsic to both human NBDs, as the Walker A box lysine mutations abolish this activity. At low protein concentration, the NBDs display an initial slower nonlinear phase in AK activity, suggesting that the activity results from homodimerization. Interestingly, the G551D gating mutation has an exaggerated nonlinear phase compared with the wild type and may indicate this mutation affects the ability of NBD1 to dimerize. hNBD1 and hNBD2 mixing experiments resulted in an 8-57-fold synergistic enhancement in AK activity suggesting heterodimer formation, which supports a common theme in ABC transporter models. A CFTR gating mechanism model based on adenylate kinase activity is proposed.