Now showing items 1-20 of 2324

    • An efficient assay for identification and quantitative evaluation of potential polysialyltransferase inhibitors

      Guo, Xiaoxiao; Malcolm, Jodie R.; Ali, Marrwa M.; Ribeiro Morais, Goreti; Shnyder, Steven D.; Loadman, Paul M.; Patterson, Laurence H.; Falconer, Robert A. (2020-05)
      The polysialyltransferases (polySTs) catalyse the polymerisation of polysialic acid, which plays an important role in tumour metastasis. While assays are available to assess polyST enzyme activity, there is no methodology available specifically optimised for identification and quantitative evaluation of potential polyST inhibitors. The development of an HPLC-fluorescence-based enzyme assay described within includes a comprehensive investigation of assay conditions, including evaluation of metal ion composition, enzyme, substrate and acceptor concentrations, temperature, pH, and tolerance to DMSO, followed by validation using known polyST inhibitors. Thorough analysis of each of the assay components provided a set of optimised conditions. Under these optimised conditions, the experimentally observed Ki value for CMP, a competitive polyST inhibitor, was strongly correlated with the predicted Ki value, based on the classical Cheng-Prusoff equation [average fold error (AFE) = 1.043]. These results indicate that this assay can provide medium-throughput analysis for enzyme inhibitors with high accuracy, through determining the corresponding IC50 values with substrate concentration at the KM, without the need to perform extensive kinetic studies for each compound. In conclusion, an in vitro cell-free assay for accurate assessment of polyST inhibition is described. The utility of the assay for routine identification of potential polyST inhibitors is demonstrated, allowing quantitative measurement of inhibition to be achieved, and exemplified through assessment of full competitive inhibition. Given the considerable and growing interest in the polySTs as important anti-metastatic targets in cancer drug discovery, this is a vital tool to enable preclinical identification and evaluation of novel polyST inhibitors.
    • Outcomes of implementing Team-Based Learning (TBL): the experiences of UK educators

      Nelson, M.; Tweddell, Simon (The Researching, Advancing and Inspiring Student Engagement (RAISE) Network, 2020-05)
      Team-Based Learning (TBL) is a collaborative learning model that refocuses classroom time to solving relevant problems instead of dispensing information. This is accomplished by a pre-class readiness assurance process that promotes accountability to self-directed learning and teamwork. While research related to the student experience with TBL is present in the literature, there is a relative lack of research published on the experiences of academic staff with TBL. Using a qualitative approach and a semi-structured interview format, this study explored the experiences of 26 academic staff in the UK who implemented TBL using a semi-structured interview format. Thematic analysis of interview text yielded five themes related to curriculum design, student outcomes, and the professional development of academic staff.
    • Structural similarity in chiral-achiral multi-component crystals

      Scowen, I.J.; Alomar, T.S.; Munshi, T.; Seaton, Colin C. (2020)
      The creation of multi-component crystals between chiral and achiral components has gained increased interest in recent years. In many cases the overall crystal structure is similar with the creation of a pseudo-inversion centre in the enantiopure case. This allows for the formation of solid solutions between the two extremes, which may have applications within chiral resolution. Utilising a combination of database mining, computational prediction and experimental screening, the frequency of formation for such materials has been investigated showing that for co-crystals this occurs more frequently than for salts, though there is a limited number of samples to draw structural conclusions. Computational modelling indicates the prediction of such systems can be challenging due to the similarities in energy of many crystal structures, so development of tools to design such systems is required to fully utilise these concepts.
    • Re-evaluating cyclosporine A as a hair growth-promoting agent in human scalp hair follicles

      Hawkshaw, N.J.; Haslam, I.S.; Ansell, David M.; Shamalak, A.; Paus, R. (2015-08)
      Cyclosporine A (CsA) has long been recognized as a potent hair growth stimulator in both humans and rodent. The induction of a dose-dependent hypertrichosis is one of the most frequent adverse effects of long-term CsA therapy (Lutz, 1994). However, it is unclear how this immunosuppressant induces hypertrichosis in patients or stimulates hair growth in human scalp skin transplanted on nude mice (Gilhar et al., 1988; Gilhar et al., 1991).
    • Endocrine drivers of photoperiod response

      Helfer, Gisela; Dumbell, R. (2020-04)
      Life in a seasonally variable environment has evolved to interpret the time of year through day length (photoperiod) which is translated into a neurochemical signal. In mammals, the pars tuberalis is a key site where seasonal time signal (melatonin) interfaces and relays photoperiodic information to the hypothalamus via thyrotropin. Recent work has elucidated a potential circannual clock in ‘calendar cells’ of the pars tuberalis. In the hypothalamus, tanycytes are an integral part of the hypothalamic network. Previous studies show the importance of local synthesis of thyroid hormone and retinoic acid in tanycytes. Recently novel downstream neuroendocrine signals, e.g. VGF, FGF21 and chemerin, were identified to govern seasonally appropriate phenotype. Additionally, the hypothalamic-pituitary-growth axis has been implicated in seasonally bodyweight and torpor regulation. Here, we will focus on the endocrine drivers of photoperiod response and highlight novel downstream effects on bodyweight and growth focusing on recent findings from seasonal rodent studies.
    • Oestrogen promotes healing in a bacterial LPS model of delayed cutaneous wound repair

      Crompton, R.; Williams, H.; Ansell, David M.; Campbell, Laura; Holden, K.; Cruickshank, S.; Hardman, M.J. (2016-04)
      Wound infection is a major clinical problem, yet understanding of bacterial host interactions in the skin remains limited. Microbe-derived molecules, known as pathogen-associated molecular patterns, are recognised in barrier tissues by pattern-recognition receptors. In particular, the pathogen-associated molecular pattern, lipopolysaccharide (LPS), a component of microbial cell walls and a specific ligand for Toll-like receptor 4, has been widely used to mimic systemic and local infection across a range of tissues. Here we administered LPS derived from Klebsiella pneumoniae, a species of bacteria that is emerging as a wound-associated pathogen, to full-thickness cutaneous wounds in C57/BL6 mice. Early in healing, LPS-treated wounds displayed increased local apoptosis and reduced proliferation. Subsequent healing progression was delayed with reduced re-epithelialisation, increased proliferation, a heightened inflammatory response and perturbed wound matrix deposition. Our group and others have previously demonstrated the beneficial effects of 17β-estradiol treatment across a range of preclinical wound models. Here we asked whether oestrogen would effectively promote healing in our LPS bacterial infection model. Intriguingly, co-treatment with 17β-estradiol was able to promote re-epithelialisation, dampen inflammation and induce collagen deposition in our LPS-delayed healing model. Collectively, these studies validate K. pneumoniae-derived LPS treatment as a simple yet effective model of bacterial wound infection, while providing the first indication that oestrogen could promote cutaneous healing in the presence of infection, further strengthening the case for its therapeutic use.
    • Wound healing protects against chemotherapy-induced alopecia in young rats via up-regulating interleukin-1β-mediated signaling

      Stojadinovic, O.; Wikramanayake, T.C.; Villasante Fricke, A.C.; Yin, N.C.; Liang, L.; Hinde, E.; Escandon, J.; Tomic-Canic, M.; Ansell, David M.; Paus, R.; et al. (2017-05-30)
      Wound healing is a complex process regulated by various cell types and a plethora of mediators. While interactions between wounded skin and the hair follicles (HFs) could induce HF neogenesis or promote wound healing, it remains unknown whether the wound healing-associated signaling milieu can be manipulated to protect against alopecia, such as chemotherapy-induced alopecia (CIA). Utilizing a well-established neonatal rat model of CIA, we show here that skin wounding protects from alopecia caused by several clinically relevant chemotherapeutic regimens, and that protection is dependent on the time of wounding and hair cycle stage. Gene expression profiling unveiled a significant increase in interleukin-1 beta (IL-1β) mediated signaling by skin wounding. Subsequently, we showed that IL-1β is sufficient and indispensable for mediating the CIA-protective effect. Administration of IL-1β alone to unwounded rats exhibited local CIA protection while IL-1β neutralization abrogated CIA protection by wounding. Mechanistically, IL-1β retarded postnatal HF morphogenesis, making HFs at the wound sites or IL-1β treated areas damage-resistant while the rats developed total alopecia elsewhere. We conclude that wound healing switches the cutaneous cytokine milieu to an IL-1β-dominated state thus retarding HF growth progression and rendering the HFs resistant to chemotherapy agents. In the future, manipulation of HF progression through interfering with the IL-1β signaling milieu may provide therapeutic benefits to a variety of conditions, from prevention of CIA to inhibition of hair growth and treatment of hirsutism.
    • The battle of the bulge: re-evaluating hair follicle stem cells in wound repair

      Garcin, C.L.; Ansell, David M. (2017-02)
      The hair follicle has an established role in wound re-epithelialisation, a phenomenon that has been appreciated since at least the first half of the last century. The bulge niche, one location of hair follicle epithelial stem cells has been of particular interest to researchers over recent years, with numerous studies showing its ability to directly contribute to epidermal repair. However, recent work has highlighted other progenitor regions of the hair follicle that appear to act as stem cells during epidermal repair. In addition, several studies within the last 12 months have questioned the importance of the bulge during re-epithelialisation, producing conflicting literature. Here we provide a new model to demonstrate how several important differences in experimental design between studies could account for these seemingly opposing findings, which may have implications for how future studies are conducted.
    • Epithelial-to-mesenchymal stem cell transition in a human organ: Lessons from Lichen Planopilaris

      Imanishi, H.; Answell, David M.; Chéret, J.; Harries, M.; Bertolini, M.; Sepp, N.; Biro, T.; Poblet, E.; Jimenez, F.; Hardman, J.; et al. (2018-03-01)
      Epithelial-to-mesenchymal transition (EMT) is critical for embryonic development and wound healing, and occurs in fibrotic disease and carcinoma. Here, we show that EMT also occurs within the bulge, the epithelial stem cell (eSC) niche of human scalp hair follicles, during the inflammatory permanent alopecia, lichen planopilaris. We show that a molecular EMT signature can be experimentally induced in healthy human eSCs in situ by antagonizing E-cadherin, combined with transforming growth factor-β1, epidermal growth factor, and IFN-γ administration, which to our knowledge has not been reported previously. Moreover, induction of EMT within primary human eSCs can be prevented and even partially reversed ex vivo by peroxisome proliferator−activated receptor-γ agonists, likely through suppression of the transforming growth factor-β signaling pathway. Furthermore, we show that peroxisome proliferator−activated receptor-γ agonists also attenuates the EMT signature even in lesional lichen planopilaris hair follicles ex vivo. We introduce lichen planopilaris as a model disease for pathological EMT in human adult eSCs, report a preclinical assay for therapeutically manipulating eSC EMT within a healthy human (mini-)organ, and show that peroxisome proliferator−activated receptor-γ agonists are promising agents for suppressing and partially reversing EMT in human hair follicles eSCs ex vivo, including in lichen planopilaris.
    • The phylogenetic landscape and nosocomial spread of the multidrug-resistant opportunist Stenotrophomonas maltophilia

      Groschel, M.I.; Meehan, Conor J.; Barilar, I.; Diricks, M.; Gonzaga, A.; Steglich, M.; Conchillo-Solé, O.; Scherer, I.-C.; Mamat, U.; Luz, C.F.; et al. (2020-04)
      Recent studies portend a rising global spread and adaptation of human- or healthcare- associated pathogens. Here, we analyse an international collection of the emerging, multi-drug-resistant, opportunistic pathogen Stenotrophomonas maltophilia from 22 countries to infer population structure and clonality at a global level. We show that the S. maltophilia complex is divided into 23 monophyletic lineages, most of which harbour strains of all degrees of human virulence. Lineage Sm6 comprises the highest rate of human-associated strains, linked to key virulence and resistance genes. Transmission analysis identifies potential outbreak events of genetically closely related strains isolated within days or weeks in the same hospitals.
    • Using a Modified Lymphocyte Genome Sensitivity (LGS) Test or TumorScan Test to Detect Cancer at an Early Stage in Each Individual

      Anderson, Diana; Najafzadeh, Mojgan; Scally, Andy J.; Jacob, B.K.; Griffith, John; Chaha, R.; Linforth, R.; Soussaline, M.; Soussaline, F. (2019-01-03)
      Our previous case-control study observed isolated lymphocytes from 208 individuals and determined the differences in the sensitivity to genomic damage of lymphocytes derived from cancer patients, pre/suspect cancer patients and healthy volunteers using the Comet assay (Anderson et al, 2014). We adapted the LGS technique using a slightly different method and examined 700 more blood samples from 598 patients with cancer or suspected cancer and 102 healthy individuals. To help increase the sensitivity of the test and detect cancer at the level of each individual, we joined with the IMSTAR team who analysed our cells with their fully automated Pathfinder™ cell reader-analyser system. With this reading and analysis system 4,000 to 10,000 cells were able to be read per slide. The new test which is called TumorScan is a highly sensitive test to detect any cancer at an early stage through the response of the white blood cells to UV treatment. These patient blood samples have also been collected at the stage before confirming diagnosis and treatment. There were four of these individuals with cancer who had received anti-cancer treatment. The results from these patients showed a reverse pattern compared to non-treated cancer patients and followed the pattern seen in healthy individuals. The results are consistent with the early results as reported in the above 2014 paper. Given the results from these samples were in a particularly challenging subgroup, whose cancer status was difficult to distinguish, the data suggest that the technique using the TumorScan system could exceed the area under the ROC curve >93% obtained in the earlier study on a group basis, whereas this present study was to detect cancer at an early stage in each individual.
    • ROS-induced Oxidative Damage in Lymphocytes Ex Vivo/in Vitro From Healthy Individuals and MGUS Patients: Protection by Myricetin Bulk and Nanoforms

      Akhtar, Shabana; Najafzadeh, Mojgan; Isreb, Mohammad; Newton, L.; Gopalan, Rajendran C.; Anderson, Diana (2020-04)
      We investigated the protective role of myricetin bulk and nanoforms, against reactive oxygen species (ROS)-induced oxidative stress caused by hydrogen peroxide and tertiary-butyl hydro peroxide in lymphocytes in vitro from healthy individuals and those from pre-cancerous patients suffering with monoclonal gammopathy of undetermined significance (MGUS). The change in intracellular reactive oxygen species was measured once cells were treated with myricetin bulk forms and nanoforms with and without either hydrogen peroxide or tertiary-butyl hydro peroxide co-supplementation. The direct and indirect antioxidant activity of myricetin was spectrofluometrically measured using the fluorescent dye 2',7'-dichlorofluorescin diacetate and using the Comet assay, respectively. Hydrogen peroxide (50 µM) and tertiary-butyl hydro peroxide (300 µM) induced a higher level of reactive oxygen species-related DNA damage and strand breaks. Addition of myricetin nanoform (20 µM) and bulk (10 µM) form could, however, significantly prevent hydrogen peroxide- and tertiary-butyl hydro peroxide-induced oxidative imbalances and the nanoform was more effective. Glutathione levels were also quantified using a non-fluorescent dye. Results suggest that myricetin treatment had no significant effect on the cellular antioxidant enzyme, glutathione. The current study also investigates the effect of myricetin on the induction of double-strand breaks by staining the gamma-H2AX foci immunocytochemically. It was observed that myricetin does not induce double-strand breaks at basal levels rather demonstrated a protective effect.
    • Oxidised LDL activates blood platelets through CD36/NOX2-mediated inhibition of the cGMP/protein kinase G signalling cascade

      Magwenzi, S.; Woodward, C.; Wraith, K.S.; Aburima, A.; Raslan, Z.; Jones, Huw S.; McNeil, C.; Wheatcroft, S.; Yuldasheva, N.; Febbriao, M.; et al. (2015-04-23)
      Oxidized low-density lipoprotein (oxLDL) promotes unregulated platelet activation in dyslipidemic disorders. Although oxLDL stimulates activatory signaling, it is unclear how these events drive accelerated thrombosis. Here, we describe a mechanism for oxLDL-mediated platelet hyperactivity that requires generation of reactive oxygen species (ROS). Under arterial flow, oxLDL triggered sustained generation of platelet intracellular ROS, which was blocked by CD36 inhibitors, mimicked by CD36-specific oxidized phospholipids, and ablated in CD36(-/-) murine platelets. oxLDL-induced ROS generation was blocked by the reduced NAD phosphate oxidase 2 (NOX2) inhibitor, gp91ds-tat, and absent in NOX2(-/-) mice. The synthesis of ROS by oxLDL/CD36 required Src-family kinases and protein kinase C (PKC)-dependent phosphorylation and activation of NOX2. In functional assays, oxLDL abolished guanosine 3',5'-cyclic monophosphate (cGMP)-mediated signaling and inhibited platelet aggregation and arrest under flow. This was prevented by either pharmacologic inhibition of NOX2 in human platelets or genetic ablation of NOX2 in murine platelets. Platelets from hyperlipidemic mice were also found to have a diminished sensitivity to cGMP when tested ex vivo, a phenotype that was corrected by infusion of gp91ds-tat into the mice. This study demonstrates that oxLDL and hyperlipidemia stimulate the generation of NOX2-derived ROS through a CD36-PKC pathway and may promote platelet hyperactivity through modulation of cGMP signaling.
    • Physiologically relevant screening of polyphenol-rich commercial preparations for bioactivity in vascular endothelial cells and application to healthy volunteers: A viable workflow and a cautionary tale.

      Jones, Huw S.; Papageorgiou, M.; Gordon, A.; Ehtesham; Wells, L.K.; Javed, Z.; Greetham, S.; Doyle, B.; Hayes, N.; Rigby, A.; et al. (2020-03)
      This study describes the screening of 13 commercially-available plant extracts for pharmacological activity modulating vascular function using an endothelial cell model. A French maritime pine bark extract (FMPBE) was found to have the greatest effect upon nitric oxide availability in control (181% ± 36% of untreated cells) and dysfunctional cells (132% ± 8% of untreated control cells). In healthy volunteers, the FMPBE increased plasma nitrite concentrations 8 h post-consumption compared to baseline (baseline corrected median 1.71 ± 0.38 (25% IQR) and 4.76 (75% IQR) µM, p < 0.05). This was followed by a placebo-controlled, healthy volunteer study, which showed no effects on plasma nitrite. It was confirmed that different batches of extract had been used in the healthy volunteer studies, and this second batch lacked bioactivity, assessed using the in vitro model. No difference in plasma catechin levels was seen at 8 h following supplementation between the studies (252 ± 194 nM versus 50 ± 64 nM, p > 0.05), however HPLC-UV fingerprinting showed that the new batch had a 5-15% in major constituents (including procyanidins A2, B1 and B2) compared to the original batch. This research describes a robust mechanism for screening bioactive extracts for vascular effects. It also highlights batch variability as a significant limitation when using complex extracts for pharmacological activity, and suggests the use of in vitro systems as a tool to identify this problem in future studies.
    • Effectiveness of short term heat acclimation on intermittent sprint performance with moderately trained females controlling for menstrual cycle phase

      Garrett, A.T.; Dodd, E.; Biddlecombe, V.; Gleadall-Siddall, D.; Burke, R.; Shaw, J.; Bray, J.; Jones, Huw S.; Abt, G.; Gritt, J. (2019-11)
      Introduction: Investigate the effectiveness of short-term heat acclimation (STHA), over 5-days (permissive dehydration), on an intermittent sprint exercise protocol (HST) with females. Controlling for menstrual cycle phase. Materials and Methods: Ten, moderately trained, females (Mean [SD]; age 22.6 [2.7] y; stature 165.3 [6.2] cm; body mass 61.5 [8.7] kg; VO˙ 2 peak 43.9 [8.6] mL·kg−1 ·min−1 ) participated. The HST (31.0◦C; 50%RH) was 9 × 5 min (45-min) of intermittent exercise, based on exercise intensities of female soccer players, using a motorized treadmill and Wattbike. Participants completed HST1 vs. HST2 as a control (C) trial. Followed by 90 min, STHA (no fluid intake), for five consecutive days in 39.5◦C; 60%RH, using controlled-hyperthermia (∼rectal temperature [Tre] 38.5◦C). The HST3 occurred within 1 week after STHA. The HST2 vs HST3 trials were in the luteal phase, using self-reported menstrual questionnaire and plasma 17β-estradiol. Results: Pre (HST2) vs post (HST3) STHA there was a reduction at 45-min in Tre by 0.20◦C (95%CI −0.30 to −0.10◦C; d = 0.77); Tsk (−0.50; −0.90 to −0.10◦C; d = 0.80); and Tb (−0.25; −0.35 to −0.15◦C; d = 0.92). Cardiac frequency reduced at 45-min (−8; −16 to −1 b·min−1 ; d = 1.11) and %PV increased (7.0; −0.4 to 14.5%: d = 1.27). Mean power output increased across all nine maximal sprints by 56W (−26 to 139W; d = 0.69; n = 9). There was limited difference (P > 0.05) for these measures in HST1 vs HST2 C trial. Discussion: Short-term heat acclimation (5-days) using controlled-hyperthermia, leads to physiological adaptation during intermittent exercise in the heat, in moderately trained females when controlling for menstrual cycle phase.
    • The effects of acute interval exercise and strawberry intake on postprandial lipemia

      O'Doherty, A.F.; Jones, Huw S.; Sathyapalan, T.; Ingle, L.; Carroll, S. (2017-11)
      Purpose: Raised postprandial triglycerides (TAG) and related oxidative stresses are strongly associated with increased cardiovascular disease (CVD) risk. Acute exercise and strawberry ingestion independently ameliorate postprandial lipid excursions and oxidative stress. However, the combined effects of these lifestyle interventions is unknown. We investigated whether acute exercise and strawberry consumption improved postprandial responses to an oral fat tolerance test (OFTT) in overweight/obese males. Methods: Overweight/obese adult males underwent four separate OFTT (73g fat, 33g carbohydrate) with blood sampled at baseline and hourly for 4 h after OFTT. Two OFTT contained 25g freeze-dried strawberries and two contained strawberry flavouring (placebo). Participants performed 40 minutes of submaximal high intensity interval cycling exercise (HIIE) 16 h before one strawberry and one placebo OFTT, and rested before the remaining two OFTT. Serum TAG was analysed and TAG area under curve (AUC) and incremental AUC (iAUC) were calculated. Oxidative stress markers were measured at baseline and 4 h. Differences between conditions (strawberry/placebo and exercise/rest) were assessed using repeated measures ANOVA. Results: Ten males (Age, 31.5 IQR 17.8 years; BMI, 29.9 ±1.8 kg.m-2) completed the study. TAG AUC was 1.5 mmol.4h-1.L-1 lower for the exercise conditions compared to the rest conditions (95% confidence interval [CI]= -2.3 to 0.8, p= 0.001). TAG AUC was not different between the strawberry and placebo conditions (CI= -1.3 to 0.6, p= 0.475). TAG iAUC was 0.5 mmol.4h-1.L-1 greater for the strawberry compared to the placebo conditions (CI= 0.1 to 1.0, p= 0.021). There were no changes in markers of lipid related oxidative stress (P> 0.05). Conclusion: Acute submaximal HIIE appears effective in reducing postprandial lipaemia in overweight/obese adult males. However, strawberry ingestion did not improve postprandial TAG.
    • The dietary flavonol quercetin ameliorates angiotensin II-induced redox signaling imbalance in a human unbilical vein endothelial cell model of endothelial dysfunction via ablation of p47phox expression

      Jones, Huw S.; Gordon, A.; Magwensi, S.G.; Naseem, K.; Atkin, S.L.; Courts, F.L. (Wiley, 2016-04)
      Quercetin is reported to reduce blood pressure in hypertensive but not normotensive humans, but the role of endothelial redox signaling in this phenomenon has not been assessed. This study investigated the effects of physiologically obtainable quercetin concentrations in a human primary cell model of endothelial dysfunction in order to elucidate the mechanism of action of its antihypertensive effects. Angiotensin II (100 nM, 8 h) induced dysfunction, characterized by suppressed nitric oxide availability (85 ± 4% p<0.05) and increased superoxide production (136 ± 5 %, p<0.001). These effects were ablated by an NADPH oxidase inhibitor. Quercetin (3 μM, 8 h) prevented angiotensin II induced changes in nitric oxide and superoxide levels, but no effect upon nitric oxide or superoxide in control cells. The NADPH oxidase subunit p47(phox) was increased at the mRNA and protein levels in angiotensin II-treated cells (130 ± 14% of control, p<0.05), which was ablated by quercetin co-treatment. Protein kinase C activity was increased after angiotensin II treatment (136 ± 51%), however this was unaffected by quercetin co-treatment. Physiologically obtainable quercetin concentrations are capable of ameliorating angiotensin II-induced endothelial nitric oxide and superoxide imbalance via protein kinase C-independent restoration of p47(phox) gene and protein expression.
    • Reduction of diagnostic and treatment delays reduces rifampicin-resistant tuberculosis mortality in Rwanda

      Ngabonziza, J.-C.S.; Habimana, Y.M.; Decroo, T.; Migambi, P.; Dushime, A.; Mazarati, J.B.; Rigouts, L.; Affolabi, D.; Ivan, E.; Meehan, Conor J.; et al. (2020-03-01)
      SETTING: In 2005, in response to the increasing prevalence of rifampicin-resistant tuberculosis (RR-TB) and poor treatment outcomes, Rwanda initiated the programmatic management of RR-TB, including expanded access to systematic rifampicin drug susceptibility testing (DST) and standardised treatment.OBJECTIVE: To describe trends in diagnostic and treatment delays and estimate their effect on RR-TB mortality.DESIGN: Retrospective analysis of individual-level data including 748 (85.4%) of 876 patients diagnosed with RR-TB notified to the World Health Organization between 1 July 2005 and 31 December 2016 in Rwanda. Logistic regression was used to estimate the effect of diagnostic and therapeutic delays on RR-TB mortality.RESULTS: Between 2006 and 2016, the median diagnostic delay significantly decreased from 88 days to 1 day, and the therapeutic delay from 76 days to 3 days. Simultaneously, RR-TB mortality significantly decreased from 30.8% in 2006 to 6.9% in 2016. Total delay in starting multidrug-resistant TB (MDR-TB) treatment of more than 100 days was associated with more than two-fold higher odds for dying. When delays were long, empirical RR-TB treatment initiation was associated with a lower mortality.CONCLUSION: The reduction of diagnostic and treatment delays reduced RR-TB mortality. We anticipate that universal testing for RR-TB, short diagnostic and therapeutic delays and effective standardised MDR-TB treatment will further decrease RR-TB mortality in Rwanda.
    • Structural and reactivity analyses of nitrofurantoin 4 dimethylaminopyridine salt using spectroscopic and density functional theory calculations

      Khan, E.; Shukla, A.; Srivastava, K.; Gangopadhyay, D.; Assi, Khaled H.; Tandon, P.; Vangala, Venu R. (2019-08-09)
      Pharmaceutical salt, nitrofurantoin–4-dimethylaminopyridine (NF-DMAP), along with its native components NF and DMAP are scrutinized by FT-IR and FT-Raman spectroscopy along with density functional theory so that an insight into the H-bond patterns in the respective crystalline lattices can be gained. Two different functionals, B3LYP and wB97X-D, have been used to compare the theoretical results. The FT-IR spectra obtained for NF-DMAP and NF clearly validate the presence of C33–H34⋅⋅⋅O4 and N23–H24⋅⋅⋅N9 hydrogen bonds by shifting in the stretching vibration of –NH and –CH group of DMAP+ towards the lower wavenumber side. To explore the significance of hydrogen bonding, quantum theory of atoms in molecules (QTAIM) has been employed, and the findings suggest that the N23–H24⋅⋅⋅N9 bond is a strong intermolecular hydrogen bond. The decrement in the HOMO-LUMO gap, which is calculated from NF → NF-DMAP, reveals that the active pharmaceutical ingredient is chemically less reactive compared to the salt. The electrophilicity index (ω) profiles for NF and DMAP confirms that NF is acting as electron acceptor while DMAP acts as electron donor. The reactive sites of the salt are plotted by molecular electrostatic potential (MEP) surface and calculated using local reactivity descriptors.
    • Subjective Verticality Is Disrupted by Astigmatic Visual Distortion in Older People

      Elliott, David B.; Black, A.A.; Wood, J.M. (2020-04-15)
      PURPOSE: There is little research evidence to explain why older adults have more problems adapting to new spectacles incorporating astigmatic changes than younger adults. We tested the hypothesis that astigmatic lenses oriented obliquely would lead to errors in verticality perception that are greater for older than younger adults. METHODS: Participants included 12 young (mean ± SD age 25.1 ± 5.0 years) and 12 older (70.2 ± 6.3 years) adults with normal vision. Verticality perception was assessed using a computer-based subjective visual vertical (SVV) task, under static and dynamic (in the presence of a moving peripheral distractor) conditions and when viewing targets through the near refractive correction (control condition), and two forms of astigmatic lenses oriented in the vertical, horizontal, and oblique meridians. RESULTS: The older group demonstrated much greater dynamic SVV errors (e.g., 3.4° for the control condition) than the younger group (1.2°, P = 0.002), larger errors with vertical and horizontal astigmatic lenses (older group 4.1°and 5.2° for toric and magnifier lenses vs. younger group 1.2° and 1.4°, respectively, P < 0.001), and a larger influence of the oblique astigmatic lenses (older group 5.6° vs. younger group 2.1°, P<0.001). CONCLUSIONS: Astigmatic lenses produced little or no errors in SVV in young adults, but large static and dynamic SVV errors in older adults. This indicates a greater reliance on visual input with increased age for SVV, and helps explain why oblique astigmatic refractive corrections can cause dizziness in older patients and why they report greater difficulties adapting to new spectacles with astigmatic changes.