Reflections on a research initiative aimed at enhancing the role of African languages in education in South Africa

In the South African educational domain, there are an increasing number of initiatives which attempt to address the inequities in the system by providing support in an African language at various levels. Many of these initiatives use translation of texts in various subject areas as a major method of support which necessarily involves terminology development. This article puts forward the argument that although linguistic andconceptual development are inextricably linked, provision of translations, terms and word lists may not be sufficient to encourage ‘deep’ learning of the key concepts in the disciplinary content areas. The challenges arising out of the present educational context in South Africa require a more holistic approach, including language provision and management, professional translation and back translation, more inclusive methodsof terminology development with richer contextualization and the enrichment of teachers’ pedagogic content knowledge. The argument arises out of a re-examination of the findings from research into the development of two multilingual resource books for use by teachers of mathematics and science at secondary school level. These resources were developed in order to facilitate understanding of key concepts in themathematics and science disciplines and will undergo a re-appraisal of the extent of their effectiveness in meeting these aims

Measurement of apolipoprotein E and amyloid β clearance rates in the mouse brain using bolus stable isotope labeling

BACKGROUND: Abnormal proteostasis due to alterations in protein turnover has been postulated to play a central role in several neurodegenerative diseases. Therefore, the development of techniques to quantify protein turnover in the brain is critical for understanding the pathogenic mechanisms of these diseases. We have developed a bolus stable isotope-labeling kinetics (SILK) technique coupled with multiple reaction monitoring mass spectrometry to measure the clearance of proteins in the mouse brain. RESULTS: Cohorts of mice were pulse labeled with (13) C(6)-leucine and the brains were isolated after pre-determined time points. The extent of label incorporation was measured over time using mass spectrometry to measure the ratio of labeled to unlabeled apolipoprotein E (apoE) and amyloid β (Aβ). The fractional clearance rate (FCR) was then calculated by analyzing the time course of disappearance for the labeled protein species. To validate the technique, apoE clearance was measured in mice that overexpress the low-density lipoprotein receptor (LDLR). The FCR in these mice was 2.7-fold faster than wild-type mice. To demonstrate the potential of this technique for understanding the pathogenesis of neurodegenerative disease, we applied our SILK technique to determine the effect of ATP binding cassette A1 (ABCA1) on both apoE and Aβ clearance. ABCA1 had previously been shown to regulate both the amount of apoE in the brain, along with the extent of Aβ deposition, and represents a potential molecular target for lowering brain amyloid levels in Alzheimer's disease patients. The FCR of apoE was increased by 1.9- and 1.5-fold in mice that either lacked or overexpressed ABCA1, respectively. However, ABCA1 had no effect on the FCR of Aβ, suggesting that ABCA1 does not regulate Aβ metabolism in the brain. CONCLUSIONS: Our SILK strategy represents a straightforward, cost-effective, and efficient method to measure the clearance of proteins in the mouse brain. We expect that this technique will be applicable to the study of protein dynamics in the pathogenesis of several neurodegenerative diseases, and could aid in the evaluation of novel therapeutic agents

Understanding patterns of contraceptive use among never married Mexican American women

Background: Non-marital fertility differs considerably by race, ethnicity, and nativity. These differences arise largely from racial and ethnic disparities in contraceptive practices. Empirical work has not assessed the relative importance of the various mechanisms proposed to account for racial, ethnic, and nativity differences in contraceptive behavior among never married women. Objective: Our objective is to describe racial, ethnic, and nativity disparities in contraceptive practices and determine the relative importance of the various mechanisms proposed to explain those disparities among never married, non-cohabiting women. Methods: Pooling data from the 2006‒2010 and 2011‒2013 National Survey of Family Growth (NSFG), we compare the age- and parity-standardized patterns of contraceptive use among never married, non-cohabiting Mexican immigrants, US-born Mexican Americans, Blacks, and Whites. We also examine the extent to which socioeconomic characteristics, access to family planning, and attitudes towards family life give rise to group differences in patterns of contraceptive use. Results: Never married, non-cohabiting Whites are more likely than their minority counterparts to use very effective methods of contraception. Socioeconomic disparities explain some of the group differences in contraceptive practice. Differing levels of access to family planning also explain a significant portion of the difference in contraceptive practice between Whites and Mexican immigrants. Conclusions: Policies aimed at alleviating socioeconomic inequality and differential access to family planning services may be effective at reducing disparities in contraceptive use between White and non-White never married, non-cohabiting women, especially White/Mexican-immigrant differences

Acute gamma-secretase inhibition of nonhuman primate CNS shifts amyloid precursor protein (APP) metabolism from amyloid-beta production to alternative APP fragments without amyloid-beta rebound

The accumulation of amyloid beta (Aβ) in Alzheimer’s disease is caused by an imbalance of production and clearance, which leads to increased soluble Aβ species and extracellular plaque formation in the brain. Multiple Aβ-lowering therapies are currently in development: an important goal is to characterize the molecular mechanisms of action and effects on physiological processing of Aβ, as well as other amyloid precursor protein (APP) metabolites, in models which approximate human Aβ physiology. To this end, we report the translation of the human in vivo stable-isotope-labeling kinetics (SILK) method to a rhesus monkey cisterna magna ported (CMP) nonhuman primate model, and use the model to test the mechanisms of action of a γ-secretase inhibitor (GSI). A major concern of inhibiting the enzymes which produce Aβ (β- and γ-secretase) is that precursors of Aβ may accumulate and cause a rapid increase in Aβ production when enzyme inhibition discontinues. In this study, the GSI MK-0752 was administered to conscious CMP rhesus monkeys in conjunction with in vivo stable isotope labeling, and dose-dependently reduced newly generated CNS Aβ. In contrast to systemic Aβ metabolism, CNS Aβ production was not increased after the GSI was cleared. These results indicate that most of the CNS APP was metabolized to products other than Aβ, including C-terminal truncated forms of Aβ: 1–14, 1–15 and 1–16; this demonstrates an alternative degradation pathway for CNS amyloid precursor protein during γ-secretase inhibition

Durvalumab with or without tremelimumab in patients with recurrent or metastatic head and neck squamous cell carcinoma: EAGLE, a randomized, open -label phase III study

Background: Targeting the programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) axis has demonstrated clinical benefit in recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC). Combining immunotherapies targeting PD-L1 and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) has shown evidence of additive activity in several tumor types. This phase III study evaluated the efficacy of durvalumab (an anti-PD-L1 monoclonal antibody) or durvalumab plus tremelimumab (an anti-CTLA-4 monoclonal antibody) versus standard of care (SoC) in R/M HNSCC patients. Patients and methods: Patients were randomly assigned to receive 1 : 1 : 1 durvalumab (10 mg/kg every 2 weeks [q2w]), durvalumab plus tremelimumab (durvalumab 20 mg/kg q4w plus tremelimumab 1 mg/kg q4w 4, then durvalumab 10 mg/kg q2w), or SoC (cetuximab, a taxane, methotrexate, or a fluoropyrimidine). The primary end points were overall survival (OS) for durvalumab versus SoC, and OS for durvalumab plus tremelimumab versus SoC. Secondary end points included progression-free survival (PFS), objective response rate, and duration of response. Results: Patients were randomly assigned to receive durvalumab (n 1⁄4 240), durvalumab plus tremelimumab (n 1⁄4 247), or SoC (n 1⁄4 249). No statistically significant improvements in OS were observed for durvalumab versus SoC [hazard ratio (HR): 0.88; 95% confidence interval (CI): 0.72e1.08; P 1⁄4 0.20] or durvalumab plus tremelimumab versus SoC (HR: 1.04; 95% CI: 0.85e1.26; P 1⁄4 0.76). The 12-month survival rates (95% CI) were 37.0% (30.9e43.1), 30.4% (24.7e36.3), and 30.5% (24.7 e36.4) for durvalumab, durvalumab plus tremelimumab, and SoC, respectively. Treatment-related adverse events (trAEs) were consistent with previous reports. The most common trAEs (any grade) were hypothyroidism for durvalumab and durvalumab plus tremelimumab (11.4% and 12.2%, respectively), and anemia (17.5%) for SoC. Grade !3 trAE rates were 10.1%, 16.3%, and 24.2% for durvalumab, durvalumab plus tremelimumab, and SoC, respectively. Conclusion: There were no statistically significant differences in OS for durvalumab or durvalumab plus tremelimumab versus SoC. However, higher survival rates at 12 to 24 months and response rates demonstrate clinical activity for durvalumab

Lesson from the Stoichiometry Determination of the Cohesin Complex: A Short Protease Mediated Elution Increases the Recovery from Cross-Linked Antibody-Conjugated Beads

Affinity purification of proteins using antibodies coupled to beads and subsequent mass spectrometric analysis has become a standard technique for the identification of protein complexes. With the recent transfer of the isotope dilution mass spectrometry principle (IDMS) to the field of proteomics, quantitative analysesssuch as the stoichiometry determination of protein complexesshave become achievable. Traditionally proteins were eluted from antibody-conjugated beads using glycine at low pH or using diluted acids such as HCl, TFA, or FA, but elution was often found to be incomplete. Using the cohesin complex and the anaphase promoting complex/cyclosome (APC/C) as examples, we show that a short 15-60 min predigestion with a protease such as LysC (modified on-bead digest termed protease elution) increases the elution efficiency 2- to 3-fold compared to standard acid elution protocols. While longer incubation periodssas performed in standard on-bead digestionsled to partial proteolysis of the cross-linked antibodies, no or only insignificant cleavage was observed after 15-60 min protease mediated elution. Using the protease elution method, we successfully determined the stoichiometry of the cohesin complex by absolute quantification of the four core subunits using LC-SRM analysis and 19 reference peptides generated with the EtEP strategy. Protease elution was 3-fold more efficient compared to HCl elution, but measurements using both elution techniques are in agreement with

In Vivo Human Apolipoprotein E Isoform Fractional Turnover Rates in the CNS

Apolipoprotein E (ApoE) is the strongest genetic risk factor for Alzheimer’s disease and has been implicated in the risk for other neurological disorders. The three common ApoE isoforms (ApoE2, E3, and E4) each differ by a single amino acid, with ApoE4 increasing and ApoE2 decreasing the risk of Alzheimer’s disease (AD). Both the isoform and amount of ApoE in the brain modulate AD pathology by altering the extent of amyloid beta (Aβ) peptide deposition. Therefore, quantifying ApoE isoform production and clearance rates may advance our understanding of the role of ApoE in health and disease. To measure the kinetics of ApoE in the central nervous system (CNS), we applied in vivo stable isotope labeling to quantify the fractional turnover rates of ApoE isoforms in 18 cognitively-normal adults and in ApoE3 and ApoE4 targeted-replacement mice. No isoform-specific differences in CNS ApoE3 and ApoE4 turnover rates were observed when measured in human CSF or mouse brain. However, CNS and peripheral ApoE isoform turnover rates differed substantially, which is consistent with previous reports and suggests that the pathways responsible for ApoE metabolism are different in the CNS and the periphery. We also demonstrate a slower turnover rate for CSF ApoE than that for amyloid beta, another molecule critically important in AD pathogenesis

Novel tau fragments in cerebrospinal fluid: relation to tangle pathology and cognitive decline in Alzheimer's disease

Tau is an axonal microtubule-binding protein. Tau pathology in brain and increased tau concentration in the cerebrospinal fluid (CSF) are hallmarks of Alzheimer's disease (AD). Most of tau in CSF is present as fragments. We immunoprecipitated tau from CSF and identified several endogenous peptides ending at amino acid (aa) 123 or 224 using high-resolution mass spectrometry. We raised neo-epitope-specific antibodies against tau fragments specifically ending at aa 123 and 224, respectively. With these antibodies, we performed immunohistochemistry on brain tissue and designed immunoassays measuring N-123, N-224, and x-224 tau. Immunoassays were applied to soluble brain fractions from pathologically confirmed subjects (81 AD patients, 33 controls), CSF from three cross-sectional and two longitudinal cohorts (a total of 133 AD, 38 MCI, 20 MCI-AD, 31 PSP, 15 CBS patients, and 91 controls), and neuronally- and peripherally-derived extracellular vesicles (NDEVs and PDEVs, respectively) in serum from four AD patients and four controls. Anti-tau 224 antibody stained neurofibrillary tangles and neuropil threads, while anti-tau 123 only showed weak cytoplasmic staining in AD. N-224 tau was lower in the AD soluble brain fraction compared to controls, while N-123 tau showed similar levels. N-224 tau was higher in AD compared to controls in all CSF cohorts (p < 0.001), but not N-123 tau. Decrease in cognitive performance and conversion from MCI to AD were associated with increased baseline CSF levels of N-224 tau (p < 0.0001). N-224 tau concentrations in PSP and CBS were significantly lower than in AD (p < 0.0001) and did not correlate to t-tau and p-tau. In a longitudinal cohort, CSF N-224 tau levels were stable over 6 months, with no significant effect of treatment with AChE inhibitors. N-224 tau was present in NDEVs, while N-123 tau showed comparable concentrations in both vesicle types. We suggest that N-123 tau is produced both in CNS and PNS and represents a general marker of tau metabolism, while N-224 tau is neuron-specific, present in the tangles, secreted in CSF, and upregulated in AD, suggesting a link between tau cleavage and propagation, tangle pathology, and cognitive decline

Durvalumab with or without tremelimumab in patients with recurrent or metastatic head and neck squamous cell carcinoma: EAGLE, a randomized, open-label phase III study

Head and neck squamous cell carcinoma (HNSCC) is among the 10 most common cancers worldwide, with increasing incidence.1 Approximately 10% of patients with HNSCC will be diagnosed with metastatic disease, and even when treated early, around half will have disease recurrence.2,3 The platinum-based doublet chemotherapy with cetuximab regimen has been the most widely-used therapy and considered standard of care (SoC) since it was proven effective in 2007 for recurrent/metastatic (R/M) HNSCC in the first-line setting.3,4 However, patients typically progress even after aggressive first-line therapy, and, until recently, the available options (e.g. cetuximab, methotrexate, and taxanes) have delivered limited survival benefits.3 Durvalumab is an immunotherapeutic agent that blocks the interaction between programmed cell death ligand 1 (PD-L1) and its receptors.5 Durvalumab demonstrated encouraging response rates and duration of response (DoR) with a manageable safety profile in patients with HNSCC.6 Although monotherapy agents that block the programmed cell death protein 1 (PD-1)/PD-L1 axis have shown clinical activity, immunotherapy combinations have the potential to improve upon monotherapy activity.7e9 Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and PD-L1/PD-1 pathways have largely non-redundant roles, suggesting that blockade of both could have additive or synergistic effects.10 Indeed, the combination of durvalumab and tremelimumab, an anti-CTLA-4 monoclonal antibody, was explored based on improved efficacy over monotherapy in other solid tumor types.7 This observation, in addition to the activity demonstrated by durvalumab in earlier R/M HNSCC studies, served as the rationale to evaluate durvalumab and tremelimumab in patients with R/M HNSCC. Several studies, including the EAGLE study, were initiated to evaluate combination immunotherapy regimens in various patient groups.11,12 The EAGLE study was the first phase III study to investigate durvalumab and tremelimumab in patients with R/M HNSCC who had progressed after platinumbased therapy. During the conduct of the EAGLE study, anti-PD-1 monoclonal antibodies were approved for use for R/M HNSCC progression following a platinum-based regimen. Treatment with these immunotherapies resulted in a median overall survival (OS) of 7.5e8.4 months.13,14 These immunotherapies are now recommended for second-line treatment as monotherapies for patients with R/M HNSCC.3,13,14 More recently, immunotherapy alone or in combination with platinum-based chemotherapy has shown improvements in OS in the first-line setting, underscoring the clinical utility of immunotherapy in HNSCC.15 Here, we report the results of the randomized phase III EAGLE trial evaluating durvalumab and durvalumab plus tremelimumab versus SoC therapies in patients with R/M HNSCC who have progressed following a platinumcontaining regimen