Chronic non-communicable diseases and the challenge of universal health coverage: insights from community-based cardiovascular disease research in urban poor communities in Accra,Ghana

Background

The rising burden of chronic non-communicable diseases in low and middle income countries has major implications on the ability of these countries to achieve universal health coverage. In this paper we discuss the impact of cardiovascular diseases (CVD) on primary healthcare services in urban poor communities in Accra, Ghana.

Methods

We review the evidence on the evolution of universal health coverage in Ghana and the central role of the community-based health planning services (CHPS) programme and the National Health Insurance Scheme in primary health care. We present preliminary findings from a study on community CVD knowledge, experiences, responses and access to services.

Results

The rising burden of NCDs in Ghana will affect the achievement of universal health coverage, particularly in urban areas. There is a significant unmet need for CVD care in the study communities. The provision of primary healthcare services for CVD is not accessible, equitable or responsive to the needs of target communities.

Conclusions

We consider these findings in the context of the primary healthcare system and discuss the challenges and opportunities for strengthening health systems in low and middle-income countries.

     

Direct inhibition of oncogenic KRAS by hydrocarbon-stapled SOS1 helices

Activating mutations in the Kirsten rat sarcoma viral oncogene homolog (KRAS) underlie the pathogenesis and chemoresistance of ∼30% of all human tumors, yet the development of high-affinity inhibitors that target the broad range of KRAS mutants remains a formidable challenge. Here, we report the development and validation of stabilized alpha helices of son of sevenless 1 (SAH-SOS1) as prototype therapeutics that directly inhibit wild-type and mutant forms of KRAS. SAH-SOS1 peptides bound in a sequence-specific manner to KRAS and its mutants, and dose-responsively blocked nucleotide association. Importantly, this functional binding activity correlated with SAH-SOS1 cytotoxicity in cancer cells expressing wild-type or mutant forms of KRAS. The mechanism of action of SAH-SOS1 peptides was demonstrated by sequence-specific down-regulation of the ERK-MAP kinase phosphosignaling cascade in KRAS-driven cancer cells and in a Drosophila melanogaster model of Ras85D^V12 activation. These studies provide evidence for the potential utility of SAH-SOS1 peptides in neutralizing oncogenic KRAS in human cancer.RAS signaling is a critical control point for a host of cellular functions ranging from cellular survival and proliferation to cellular endocytosis and motility (1). The on or off state of RAS is dictated by nucleotide exchange. GTP-bound RAS is the activated form that engages its downstream effectors with high avidity. The endogenous GTPase activity of RAS hydrolyzes GTP to GDP and inactivates signaling. This biochemical process is further regulated by GTPase-activating proteins (GAPs) that impair RAS signaling through increasing endogenous GTPase activity and guanine-nucleotide exchange factors (GEFs) that enhance RAS signaling by facilitating GDP release and, thus, GTP association. Given the central roles of RAS in cellular growth and metabolism, it is not surprising that cancer cells usurp its prosurvival activities to achieve immortality.Activating mutations in KRAS represent the most frequent oncogenic driving force among the RAS homologs K-, N-, and H-RAS, and are associated with poor prognosis and chemoresistance (2). KRAS mutations are present in ∼30% of human tumors and at even higher frequencies in cancers of the pancreas, lung, thyroid gland, colon, and liver. For example, in pancreatic ductal adenocarcinomas (PDAC) that carry a 5-y survival rate of less than 5%, activating KRAS mutations are present in more than 90% of tumors (3). Thus, therapeutic inhibition of RAS is among the highest priority goals of the cancer field. Because oncogenic forms of KRAS typically harbor single-point mutants that stabilize its active GTP-bound form, a host of recent small molecule and peptide development efforts have been aimed at disarming this pathologic biochemical state. The extremely high affinity of KRAS for its GTP substrate has hampered the development of competitive GTP inhibitors. However, a GDP mimetic that covalently modifies the mutant cysteine of KRAS G12C represents a promising approach to plugging the nucleotide-binding site (4). The prototype compound SML-10-70-1 demonstrated antiproliferative effects in the 25–50 μM range, although it did not appear to discriminate between KRAS-dependent and KRAS-independent growth (4). An elegant screening strategy based on covalent engagement of the G12C thiol identified promising inhibitors that target a new allosteric site adjacent to the nucleotide exchange region (5). These compounds not only switched the nucleotide-binding preference of KRAS G12C to GDP over GTP (5), favoring the inactive state, but may also diminish effector interactions, a distinct and complementary RAS-inhibitory activity exploited by another series of small molecules recently identified by in silico screening (6). Compounds that emerged from these molecular tethering and in silico strategies have demonstrated micromolar and submicromolar range antitumor responses in cancer cells driven by KRAS G12C and KRAS G12V, respectively (5, 6).Because the KRAS-GDP to KRAS-GTP transition catalyzed by the GEF, son of sevenless 1 (SOS1), represents the rate-limiting step for nucleotide exchange (7, 8), disrupting the activating SOS1/KRAS protein interaction has also been the focus of drug development efforts (9). A synthetic peptide incorporating select residues of the SOS1 helical interaction motif and structurally stabilized by hydrogen bond surrogate (HBS) chemistry yielded mid- to high-micromolar binders that inhibited wild-type Ras-ERK phosphosignaling (10). Two NMR-based fragment screens independently identified small molecules that also bind to KRAS in the mid- to high-micromolar range and disrupted SOS1-mediated RAS activation (11, 12). However, the effects of these new peptidic and small molecule agents on cancer cell viability were not evaluated (10–12). In an interesting twist, a set of recently described small molecule hits engaged the RAS–SOS1–RAS ternary complex at a unique hydrophobic pocket, activated nucleotide exchange, and perturbed phosphosignaling downstream of RAS (13). Finally, a combinatorial screening approach identified several cyclic peptides with submicromolar RAS-binding activity, but no cellular activity was observed (14). Despite the recent progress in developing small molecules and synthetic peptides to directly target RAS or RAS-SOS1, high-affinity binders with promising cellular activity across the broad spectrum of wild-type and mutant KRAS-driven cancers have remained out of reach. Thus, there is a pressing need for next-generation agents to target and disarm KRAS in human cancer cells.We have previously generated “stapled peptides” modeled after key α-helical interaction domains to disrupt oncogenic protein interactions of the BCL-2 family, p53, β-catenin, and EZH2 pathways (15–18). By sampling alternative staple positions, interrogating cellular uptake, and correlating biochemical function with antitumor activity and mechanism of action, we have generated lead compounds that form the basis for therapeutic development (16, 17, 19, 20). Here, we report the application of all-hydrocarbon stapling to recapitulate the native primary sequence and secondary structure of the RAS-interacting α-helix of SOS1. Our goal was to develop a direct inhibitor that binds the diversity of KRAS mutant forms, impairs nucleotide exchange and, importantly, broadly kills KRAS-mutant cancer cells in a sequence-specific manner by deactivating its downstream phosphosignaling cascade.     

Bilayered microelectrodes based on electrochemically deposited MnO2/polypyrrole towards fast charge transport kinetics for micro-supercapacitors

Micro-supercapacitors (MSCs) are promising power solution facilities for miniaturized portable electronic devices. Microfabrication of on-chip MSC with high specific capacitance and high energy density is still a great challenge. Herein, we report a high-performance MnO₂/polypyrrole (PPy) microelectrode based MSC (MnO₂/PPy-MSC) by modern micromachining technology. Interdigital Au micro current collectors were obtained by photolithography, physical vapor deposition and lift off. A layer of PPy was electrochemically deposited on Au current collectors followed by deposition of urchin-like MnO₂ micro/nanostructures. The electrochemical performance of MnO₂/PPy-MSC was explored employing LiClO₄/PVA gel electrolyte. The assembled MSC demonstrated a high areal capacitance of 13 mF cm⁻², an energy density of 1.07 × 10⁻³ mW h cm⁻² and a power density of 0.53 mW cm⁻². In addition, the MnO₂/PPy-MSC showed an improved cycling stability, retaining 84% of the initial capacitance after 5000 CV cycles at a scan rate of 500 mV s⁻¹. Our proposed strategy provides a versatile and promising method for the fabrication of high-performance MSCs with large-scale applications.

Micro-supercapacitors (MSCs) are promising power solution facilities for miniaturized portable electronic devices.     

Ambulatory blood pressure monitoring and management of hypertension at a cardiac clinic in Kumasi Metropolis,Ghana

Ambulatory blood pressure monitoring (ABPM) is considered a good intervention strategy to avoid misdiagnosis of hypertension and allow for targeted treatment of patients with hypertension. This study sought to assess the contribution of ABPM to blood pressure (BP) control and antihypertensive therapy at a cardiac clinic in Ghana. Medical records of 97 patients, aged 18‐85 years (mean 55), were reviewed. Among patients with clinic BP (CBP) and ambulatory BP recorded on the same day, we assessed for the different hypertension phenotypes, CBP control 6 months following ABPM, and changes to antihypertensive therapy after review of the ABPM records in patients with controlled and uncontrolled ambulatory BP. From the clinic and ambulatory BP records measured at baseline, the proportion of patients with white‐coat uncontrolled hypertension (WUCH) was 19.5% (17/87) and those with masked uncontrolled hypertension (MUCH) was 16.1% (n = 14). A significant reduction in average systolic CBP in the overall cohort (−6.2 mm Hg, P < .01) and in the uncontrolled subgroup (−8.8 mm Hg, P < .001) at follow‐up was observed. After review of the ABPM records, 51.7% of the patients on treatment had changes made in their antihypertensive therapy. Antihypertensive therapy was deintensified or left unchanged in majority of the patients with WUCH and sustained controlled hypertension. In patients with MUCH and true uncontrolled hypertension (TUCH), therapy was intensified. In conclusion, ABPM improved clinical decision‐making for antihypertensive therapy and BP control. ABPM should therefore be used more often in hypertension and cardiac clinics in low/middle‐income countries for optimal care.     

A Community-Wide Study of Malaria Reduction: Evaluating Efficacy and User-Acceptance of a Low-Cost Repellent in Northern Ghana

NO MAS (NM) mosquito repellent was evaluated in two farming villages (4 km apart) in the Kassena Nankana district of northern Ghana. We determined its efficacy against local malaria vectors, degree of user acceptance, and its effect on malaria prevalence in households using insecticide-treated bed nets. The average protective efficacy of NM against Anopheles mosquitoes over 9 hours was 89.6%. Controls averaged 86 bites/person/night versus 9 bites/person/night with the use of NM. Use of repellent was associated with a decrease of absolute malaria prevalence by 19.2% in the repellent village and by 6.5% in the control village (45.5 to 26.3, and 29.5 to 23.0, respectively). The user-acceptance rate of NM repellent was 96.1%. Ten percent (10%) of repellent users reported irritation as the main adverse effect during the period. Eighty-five percent (85%) of the users found the odor of NM appealing and 87% reported no inconvenience in applying the repellent daily.     

Early detection of recurrent breast cancer using metabolite profiling

We report on the development of a monitoring test for recurrent breast cancer, using metabolite-profiling methods. Using a combination of nuclear magnetic resonance (NMR) and two-dimensional gas chromatography-mass spectrometry (GC×GC-MS) methods, we analyzed the metabolite profiles of 257 retrospective serial serum samples from 56 previously diagnosed and surgically treated breast cancer patients. One hundred sixteen of the serial samples were from 20 patients with recurrent breast cancer, and 141 samples were from 36 patients with no clinical evidence of the disease during ～6 years of sample collection. NMR and GC×GC-MS data were analyzed by multivariate statistical methods to compare identified metabolite signals between the recurrence samples and those with no evidence of disease. Eleven metabolite markers (seven from NMR and four from GC×GC-MS) were shortlisted from an analysis of all patient samples by using logistic regression and 5-fold cross-validation. A partial least squares discriminant analysis model built using these markers with leave-one-out cross-validation provided a sensitivity of 86% and a specificity of 84% (area under the receiver operating characteristic curve = 0.88). Strikingly, 55% of the patients could be correctly predicted to have recurrence 13 months (on average) before the recurrence was clinically diagnosed, representing a large improvement over the current breast cancer-monitoring assay CA 27.29. To the best of our knowledge, this is the first study to develop and prevalidate a prediction model for early detection of recurrent breast cancer based on metabolic profiles. In particular, the combination of two advanced analytical methods, NMR and MS, provides a powerful approach for the early detection of recurrent breast cancer.     

Normal CD4+ T lymphocyte levels in HIV seronegative individuals in the Manya/Yilo Krobo communities in the Eastern region of Ghana

The goal of this study was to determine the normal levels of CD4+ T lymphocytes in healthy individuals who were HIV seronegative in the Manya and Yilo Krobo Districts of Ghana's Eastern Region. This enabled comparisons with normal CD4 count ranges established by the World Health Organization (WHO). The study population consisted of 249 HIV-seronegative clients from a mobile free Voluntary Counseling and Testing (VCT) service in communities of the two districts during a one-month period. The mean CD4 count of these individuals was 1067 cells/microl with women demonstrating higher baseline CD4 counts than men. This study found a WHO comparable HIV seronegative baseline CD4 count as well as gender-based differences in the CD4 count and CD4/CD8 ratio. Establishment of the adult baseline for the country provides important demographic data and indicates the appropriateness of current global treatment guidelines with regards to CD4 levels in Ghana.     

Torsades de pointes associated with fluoroquinolones: importance of concomitant risk factors

The fluoroquinolone antibiotics sparfloxacin, grepafloxacin, gatifloxacin, and levofloxacin have been reported to cause torsades de pointes. Pre-existing risk factors increase vulnerability to this life-threatening arrhythmia. In a 65-year-old woman with a history of hypertension, coronary artery disease, systemic lupus erythematosus, and osteomyelitis, QTc interval prolongation (605 ms) and torsades de pointes developed after the initiation of levofloxacin, 250 mg intravenously once daily. The patient was hypokalemic and mildly hypomagnesemic before the initiation of levofloxacin and at the time of occurrence of torsades de pointes. The QTc interval decreased to 399 ms within hours of discontinuation of the levofloxacin, after which she had no further arrhythmias. In this and the majority of other published cases of fluoroquinolone-associated torsades de pointes, patients had at least 1 risk factor for the arrhythmia, and most had multiple risk factors. Fluoroquinolone antibiotics should be avoided whenever possible in patients with pre-existing risk factors for torsades de pointes.