Breath biomarkers of pediatric malaria: reproducibility and response to antimalarial therapy.

BACKGROUND: Many insect-borne pathogens appear to manipulate the odors of their hosts in ways that influence vector behaviors. In our prior work, we identified characteristic changes in volatile emissions of cultured Plasmodium falciparum parasites in vitro and during natural human falciparum malaria. In the current study, we prospectively evaluate the reproducibility of these findings in an independent cohort of children in Blantyre, Malawi. METHODS: We enrolled febrile children under evaluation for malaria and collected breath from children with and without malaria, as well as healthy controls. Using gas-chromatography/mass spectrometry, we characterized breath volatiles associated with malaria. By repeated sampling of children with malaria before and after antimalarial use, we determined how breath profiles respond to treatment. In addition, we investigated the stage-specificity of biomarkers through correlation with asexual and sexual stage parasitemia. RESULTS: Our data provide robust evidence that P. falciparum infection leads to specific, reproducible changes in breath compounds. While no individual compound served as adequate classifier in isolation, selected volatiles together yielded high sensitivity for diagnosis of malaria. Overall, the results of our predictive models suggest the presence of volatile signatures that reproducibly predict malaria infection status and determine response to therapy, even in cases of low parasitemia.

Effect of the Melicoccus bijugatus leaf and fruit extracts and acidic solvents on the antimicrobial properties of chitosan-starch films.

AIM: Analysing the antimicrobial activity-against food-borne micro-organisms-of modified chitosan-starch films using formic and acetic acid as chitosan solvents and Melicoccus bijugatus leaves and fruit extracts. METHODS AND RESULTS: The films' antimicrobial activity against mesophilic aerobic bacteria, total coliform and fungi were also analysed, in accordance with the Mexican Official Norms (NOM-092-SSA1-1994, NOM-111-SSA1-1994 and NOM-113-SSA1-1994). The pH values of the films and extracts were measured, and the volatile compounds of the extracts and two films were determined by Gas Chromatography-Mass Spectrometry (GC-MS) considering the relationship among the type of compounds, extracts concentration, films' pH and the antimicrobial activity against bacteria and fungi. The best results are obtained by films with formic acid and 10% (v/v) of leaf and fruit extracts, in comparison with untreated chitosan-starch films. CONCLUSIONS: The extracts' compounds improved the films' antimicrobial capacity and inhibited the growth of micro-organisms with no previous sterilization required. It is correlated to the pH of the media, the combination of solvent/extract used and its concentration. SIGNIFICANCE AND IMPACT OF THE STUDY: This is one of the few researches where the antimicrobial activity of M. bijugatus extracts is studied. It was found that the presence of these extracts is capable of improving the antimicrobial activities of chitosan-starch films. The performance of the modified films suggests their potential application as novel food packaging materials and encourages further research.

Predictors of mortality in acute hospitalised COVID-19 pneumonia patients: A retrospective cohort study at two tertiary-level hospitals in Zambia.

BACKGROUND: The global COVID-19 pandemic has resulted in increased acute hospitalisations, a high demand for intensive care and high in-hospital mortality, placing a huge burden on healthcare systems. OBJECTIVES: To assess in-hospital mortality outcomes and associated factors in acute hospitalised COVID-19 pneumonia patients in Zambia. METHODS: We performed a retrospective cohort review of patients admitted to two tertiary-level hospitals in Zambia from 1 March 2020 to 28 February 2021. We examined the factors (demographic, clinical and laboratory) that were associated with in-hospital mortality using multivariate logistic analysis. Adjusted odds ratios with their 95% confidence intervals (CIs) are reported. RESULTS: Of 350 patients, 59.4% were aged ≥55 years and 52.6% were male. The commonest comorbidities were hypertension, diabetes mellitus (DM), HIV/AIDS and chronic kidney disease (49.6%, 28.5%, 22.0% and 8.1%, respectively). The overall in-hospital mortality rate was 42.6%, and mortality was significantly increased in patients aged ≥55 years (52.0% v. 48.0%) and in those with DM (52.1% v. 47.9%), cardiac disease (68.0% v. 32.0%), a Quick Sequential (Sepsis-Related) Organ Failure Assessment (q-SOFA) score ≥2 (75.4% v. 24.6%), and admission blood glucose levels ≥7.0 mmol/L (66.3% v. 33.7%). Compared with patients who survived, who spent a median (interquartile range) of 6 (3 - 10) days in hospital, the median time between admission and death in those who died was 2.5 (1 - 6) days. In multivariate logistic analysis, age ≥55 years, a q-SOFA score ≥2 and a random blood sugar level ≥7.0 mmol/L were predictors of in-hospital mortality, with adjusted odds ratios of 1.54 (95% CI 1.09 - 2.17), 2.17 (95% CI 1.40 - 3.38) and 1.65 (95% CI 1.18 - 2.30), respectively. Raised serum creatinine was not associated with in-hospital COVID-19 mortality after adjusting for other confounders. CONCLUSIONS: This study highlights that high in-hospital COVID-19 mortality was associated with a high q-SOFA score, hyperglycaemia on admission and older age. The study reinforces the need to invest in emergency healthcare services for optimal management of COVID-19 patients presenting with high q-SOFA scores in resource-limited countries.

Risk factors and outcomes of sepsis-associated acute kidney injury in intensive care units in Johannesburg, South Africa.

BACKGROUND: Sepsis-associated acute kidney injury (SA-AKI) has been shown to be a significant contributor to morbidity and mortality in both children and adults with critical illness. In sub-Saharan Africa, there is a lack of information on factors associated with development of SA-AKI and outcomes after intensive care unit (ICU) admission. OBJECTIVES: To assess the rate of SA-AKI, factors associated with its development, and predictors of mortality at 90 days in critically ill patients admitted to the ICU with sepsis. METHODS: This was a prospective observational study conducted at two of the biggest teaching hospitals in Johannesburg, South Africa, from 15 February 2016 to 15 February 2020. The study included consecutive patients with confirmed sepsis who were admitted to the ICU within 24 hours of admission to hospital. The primary outcome of the study was development of SA-AKI (defined according to Kidney Disease Improving Global Outcome (KDIGO) criteria), and secondary outcomes were risk factors for SA-AKI and predictors of mortality at 90 days. Multivariate logistic regression analysis was employed to determine the factors associated with SA-AKI and 90-day mortality. RESULTS: In total, 327 critically ill patients with sepsis admitted to the ICUs were included in the study. The median (interquartile range) age was 39 (30 - 52) years, and 185 patients (56.6%) developed SA-AKI. Of these patients, blacks and whites comprised 91.0% and 6.1%, respectively, and the prevalent comorbidities were HIV/AIDS (19.3%), hypertension (14.2%) and diabetes mellitus (10.1%). Patients with SA-AKI were likely to be older and of male gender, and to have cardiovascular disease, malignancies, hypotension and a low serum albumin level. In multivariate analysis, the predictors of SA-AKI were age ≥55 years (odds ratio (OR) 2.43; 95% confidence interval (CI) 1.27 - 4.65), inotropic support (OR 3.61; 95% CI 2.18 - 5.96) and a low serum albumin level (OR 2.93; 95% CI 1.40 - 6.13). SA-AKI and need for inotropic support were respectively associated with 1.9-fold and 1.7-fold increased mortality at 90 days after ICU admission. CONCLUSION: SA-AKI was found to be frequent in this study in two tertiary hospital ICUs in Johannesburg, and the need for inotropic support predicted mortality after ICU admission.

Field-induced transition within the superconducting state of CeRh2As2.

Materials with multiple superconducting phases are rare. Here, we report the discovery of two-phase unconventional superconductivity in CeRh2As2 Using thermodynamic probes, we establish that the superconducting critical field of its high-field phase is as high as 14 tesla, even though the transition temperature is only 0.26 kelvin. Furthermore, a transition between two different superconducting phases is observed in a c axis magnetic field. Local inversion-symmetry breaking at the cerium sites enables Rashba spin-orbit coupling alternating between the cerium sublayers. The staggered Rashba coupling introduces a layer degree of freedom to which the field-induced transition and high critical field seen in experiment are likely related.

The effect of maize-alfalfa intercropping on the physiological characteristics, nitrogen uptake and yield of maize.

In Northeastern China, the intensive cropping system and increased use of chemical fertilizer has caused severe problems in terms of sustainable agricultural development. Therefore, to improve agricultural sustainability and crop productivity the farming system needs to be modified in the region. A pot experiment was conducted to evaluate the effect of maize-alfalfa intercropping on the physiological characteristics, nitrogen (N) uptake and yield of the maize crops in northeast China in 2017-2018. The study findings showed that intercropping under N fertilization progressively improved the physio-agronomic indices of the maize crop as compared to mono-cropping. The grain yield, 100 seed weight and biomass dry matter of maize crop improved in intercropping when it was practiced with N fertilizer. Furthermore, intercropping with N fertilization increased the chlorophyll content of the maize crop at bell-mouthed, silking, filing and mature stages by 19%, 44%, 12%, and 9% in 2017 and by 23%, 43%, 15%, and 11% in 2018, respectively, as compared with the monocropping system. Unlike monocropping, intercropping with N fertilization increased the photosynthesis rate (14% and 15%), stomatal conductance (74% and 98%) and transpiration rate (74% and 75%) in 2017 and 2018, respectively. However, intercropping reduced intercellular CO2 (Ci ). Moreover, intercropping with N fertilization increased the maize N content of grain and leaves as well as total N uptake by 49%, 31% and 93% in 2017 and 53%, 34% and 132%, respectively, in 2018 as compared to monocropping. In conclusion, our results suggest that maize-alfalfa intercropping with optimal N fertilization provides a practical method for improving growth, yield and N accumulation in the maize crop.

Assessing the potential impact of vector-borne disease transmission following heavy rainfall events: a mathematical framework.

Predicting the impact of natural disasters such as hurricanes on the transmission dynamics of infectious diseases poses significant challenges. In this paper, we put forward a simple modelling framework to investigate the impact of heavy rainfall events (HREs) on mosquito-borne disease transmission in temperate areas of the world such as the southern coastal areas of the USA. In particular, we explore the impact of the timing of HREs relative to the transmission season via analyses that test the sensitivity of HRE-induced epidemics to variation in the effects of rainfall on the dynamics of mosquito breeding capacity, and the intensity and temporal profile of human population displacement patterns. The recent Hurricane Harvey in Texas motivates the simulations reported. Overall, we find that the impact of vector-borne disease transmission is likely to be greater the earlier the HREs occur in the transmission season. Simulations based on data for Hurricane Harvey suggest that the limited impact it had on vector-borne disease transmission was in part because of when it occurred (late August) relative to the local transmission season, and in part because of the mitigating effect of the displacement of people. We also highlight key data gaps related to models of vector-borne disease transmission in the context of natural disasters. This article is part of the theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes'. This issue is linked with the subsequent theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control'.

Cost of tuberculosis diagnosis and treatment from the patient perspective in Lusaka, Zambia.

SETTING: Urban primary health centres in Lusaka, Zambia. OBJECTIVES: 1) To estimate patient costs for tuberculosis (TB) diagnosis and treatment and 2) to identify determinants of patient costs. METHODS: A cross-sectional survey of 103 adult TB patients who had been on treatment for 1-3 months was conducted using a standardised questionnaire. Direct and indirect costs were estimated, converted into US$ and categorised into two time periods: 'pre-diagnosis/care-seeking' and 'post-diagnosis/treatment'. Determinants of patient costs were analysed using multiple linear regression. RESULTS: The median total patient costs for diagnosis and 2 months of treatment was $24.78 (interquartile range 13.56-40.30) per patient--equivalent to 47.8% of patients' median monthly income. Sex, patient delays in seeking care and method of treatment supervision were significant predictors of total patient costs. The total direct costs as a proportion of income were higher for women than men (P < 0.001). Treatment costs incurred by patients on the clinic-based directly observed treatment strategy were more than three times greater than those incurred by patients on the self-administered treatment strategy (P < 0.001). CONCLUSION: Clinic-based treatment supervision posed a significant economic burden on patients. The creation or strengthening of community-based treatment supervision programmes would have the greatest potential impact on reducing patients' TB-related costs.

Sleep duration, timing, variability and measures of adiposity among 8- to 12-year-old children with obesity.

OBJECTIVES: Sleep disruption in laboratory studies increases adiposity and decreases glucose tolerance. However, few epidemiological studies have used objective measures of sleep. This study aims to assess associations between sleep duration, timing and regularity with measures of adiposity. METHODS: This is a cross-sectional study of 188 children with obesity (age: 10.50 ± 1.39 years; body mass index: 29.24 ± 5.04 kg m-2). Nightly sleep duration, bedtime and wake time were measured by multiple-day actigraphy and parent reports. Per cent overweight (per cent over median body mass index for age and sex) was chosen as the primary measure of obesity status. Objective measures of height, weight, waist circumference, blood pressure, fasting blood lipids, glucose, insulin, glycated haemoglobin and C-reactive protein were obtained. Television screen time and total caloric intake were assessed via parent questionnaire. RESULTS: Each hour later in weekday bedtime was associated with an additional 6.17 per cent overweight (95% confidence interval [CI]: 1.42-10.92). Each hour greater in day-to-day variability in weekday bedtime and weekday wake time was associated with an additional 10.20 (95% CI: 0.50-19.91) and 10.02 (95% CI: 1.55-18.50) per cent overweight, respectively. Associations were similar after controlling for other obesity-related behaviours (television screen time, total caloric intake and physical activity.). CONCLUSIONS: Among children with obesity, later bedtime and greater variability in bedtime and wake time are associated with greater adiposity, independent of other obesity-related behaviours. Early bedtime and wake time and consistent day-to-day sleep timing may be strategies to reduce adiposity in high-risk children.

Assessing the quality of HIV/AIDS services at military health facilities in Zambia.

After rapidly scaling up HIV/AIDS-related health services, the Zambian Defence Force (ZDF) has become concerned with assuring their quality. This evaluation assesses provider performance at eight ZDF facilities based on direct observations of 191 antenatal care (ANC) consultations and 175 follow-up consultations for antiretroviral therapy (ART). In addition, 43 ZDF health providers were interviewed about the work environment and service quality. On-the-job performance varied widely: providers completed as few as 0% and as many as 100% of tasks associated with each performance standard. Overall scores averaged 66% (range: 47-93%) for ANC consultations and 60% (range: 37-100%) for ART consultations. Perceptions of the work environment were generally positive, but 57% of providers lack confidence in their clinical skills and 42% think staffing is insufficient. These findings, which point to the unique opportunities and challenges in the military setting, will be used to guide a quality improvement initiative.