Moving forward with COVID-19: Future research prospects of wastewater-based epidemiology methodologies and applications

Wastewater-based epidemiology (WBE) has been demonstrated for its great potential in tracking of coronavirus disease 2019 (COVID-19) transmission among populations despite some inherent methodological limitations. These include non-optimized sampling approaches and analytical methods; stability of viruses in sewer systems; partitioning/retention in biofilms; and the singular and inaccurate back-calculation step to predict the number of infected individuals in the community. Future research is expected to (1) standardize best practices in wastewater sampling, analysis and data reporting protocols for the sensitive and reproducible detection of viruses in wastewater; (2) understand the in-sewer viral stability and partitioning under the impacts of dynamic wastewater flow, properties, chemicals, biofilms and sediments; and (3) achieve smart wastewater surveillance with artificial intelligence and big data models. Further specific research is essential in the monitoring of other viral pathogens with pandemic potential and subcatchment applications to maximize the benefits of WBE beyond COVID-19.

In-sewer decay and partitioning of Campylobacter jejuni and Campylobacter coli and implications for their wastewater surveillance

Campylobacter jejuni and coli are two main pathogenic species inducing diarrhoeal diseases in humans, which are responsible for the loss of 33 million lives each year. Current Campylobacter infections are mainly monitored by clinical surveillance which is often limited to individuals seeking treatment, resulting in under-reporting of disease prevalence and untimely indicators of community outbreaks. Wastewater-based epidemiology (WBE) has been developed and employed for the wastewater surveillance of pathogenic viruses and bacteria. Monitoring the temporal changes of pathogen concentration in wastewater allows the early detection of disease outbreaks in a community. However, studies investigating the WBE back-estimation of Campylobacter spp. are rare. Essential factors including the analytical recovery efficiency, the decay rate, the effect of in-sewer transport, and the correlation between the wastewater concentration and the infections in communities are lacking to support wastewater surveillance. This study carried out experiments to investigate the recovery of Campylobacter jejuni and coli from wastewater and the decay under different simulated sewer reactor conditions. It was found that the recovery of Campylobacter spp. from wastewater varied with their concentrations in wastewater and depended on the detection limit of quantification methods. The concentration reduction of Campylobacter. jejuni and coli in sewers followed a two-phase reduction model, and the faster concentration reduction during the first phase is mainly due to their partitioning onto sewer biofilms. The total decay of Campylobacter. jejuni and coli varied in different types of sewer reactors, i.e. rising main vs. gravity sewer. In addition, the sensitivity analysis for WBE back-estimation of Campylobacter suggested that the first-phase decay rate constant (k₁) and the turning time point (t₁) are determining factors and their impacts increased with the hydraulic retention time of wastewater.

Effects of sewer biofilms on the degradability of carbapenems in wastewater using laboratory scale bioreactors

Carbapenems are last-resort antibiotics used to treat bacterial infections unsuccessfully treated by most common categories of antibiotics in humans. Most of their dosage is secreted unchanged as waste, thereby making its way into the urban water system. There are two major knowledge gaps addressed in this study to gain a better understanding of the effects of their residual concentrations on the environment and environmental microbiome: development of a UHPLC-MS/MS method of detection and quantification from raw domestic wastewater via direct injection and study of their stability in sewer environment during the transportation from domestic sewers to wastewater treatment plants. The UHPLC-MS/MS method was developed for four carbapenems: meropenem, doripenem, biapenem and ertapenem, and validation was performed in the range of 0.5-10 μg/L for all analytes, with limit of detection (LOD) and limit of quantification (LOQ) values ranging from 0.2-0.5 μg/L and 0.8-1.6 μg/L respectively. Laboratory scale rising main (RM) and gravity sewer (GS) bioreactors were employed to culture mature biofilms with real wastewater as the feed. Batch tests were conducted in RM and GS sewer bioreactors fed with carbapenem-spiked wastewater to evaluate the stability of carbapenems and compared against those in a control reactor (CTL) without sewer biofilms, over a duration of 12 h. Significantly higher degradation was observed for all carbapenems in RM and GS reactors (60 - 80%) as opposed to CTL reactor (5 - 15%), which indicates that sewer biofilms play a significant role in the degradation. First order kinetics model was applied to the concentration data along with Friedman's test and Dunn's multiple comparisons analysis to establish degradation patterns and differences in the degradation observed in sewer reactors. As per Friedman's test, there was a statistically significant difference in the degradation of carbapenems observed depending on the reactor type (p = 0.0017 - 0.0289). The results from Dunn's test indicate that the degradation in the CTL reactor was statistically different from that observed in either RM (p = 0.0033 - 0.1088) or GS (p = 0.0162 - 0.1088), with the latter two showing insignificant difference in the degradation rates observed (p = 0.2850 - 0.5930). The findings contribute to the understanding about the fate of carbapenems in urban wastewater and the potential application of wastewater-based epidemiology.

Late antenatal care initiation and neonatal outcomes in an ethnically diverse maternal cohort

Background

Ethnic minority status and maternal socio-economic deprivation are linked to delayed access to health care during pregnancy. The link between late antenatal care initiation and neonatal outcomes in settings with high ethnic diversity and social disadvantage is seldom explored. This study examined associations between late antenatal care initiation (first antenatal appointment >12 weeks gestation) and neonatal outcomes of preterm birth (<37 weeks gestation) and low birth weight (<2500 g) in an ethnically diverse socially disadvantaged maternal cohort.

Methods

A retrospective cross sectional study using routinely collected anonymous data of singleton births between April 2007 - March 2016 from a large UK National Health Service maternity unit in an ethnically diverse, socially disadvantaged area. Univariate and multivariate logistic regression models were used to examine the associations between late antenatal care initiation and prevalence of preterm birth and low birth weight.

Results

Of the 46,307 singleton births recorded, more than one third (34.8%) were to mothers from Black African, Black Caribbean, Indian, Pakistani, and Bangladeshi mothers. Gestational week at first antenatal appointment was available for 99.31% births among which 79.2% had their first appointment at ≤ 12 weeks, 12% at 13-20 weeks, and 8.8% at > 20 weeks. Mothers who booked at 13+ weeks were significantly more likely to have a preterm and/or low birth weight baby. Compared to mothers who booked at ≤ 12 weeks, those booking at > 20 weeks were 4.08 times (95% CI: 3.29,5.07) as likely to have an extremely preterm baby (<28 weeks of gestation) and 3.12 (CI 2.66, 3.67) times as likely to have a baby born with extremely low birthweight (<1500g).

Conclusions

Mothers in ethnically diverse socially deprived areas who started antenatal care late were at increased risk of adverse neonatal outcomes. Targeted intervention programmes and services are needed to support these mothers.

Key messages

Oral Health in the Population Assessment of Tobacco and Health Study

Tobacco use is a well-established risk factor for multiple adverse oral conditions. Few nationally representative oral health data sets encompass the current diversity of tobacco and nicotine products. This investigation examines the validity of oral health measures in the Population Assessment of Tobacco and Health (PATH) Study to assess relationships between tobacco use and oral health. Cross-sectional data from PATH Study wave 4 (N = 33,643 US adults, collected 2016-2018) were used to obtain estimates for 6 self-reported oral conditions (e.g., bone loss around teeth, tooth extractions) and compared with analogous estimates from the National Health and Nutrition Examination Survey (NHANES) cycle 2017-2018 (N = 5,856). Within the PATH Study, associations were calculated between tobacco use status and lifetime and past 12-mo experience of adverse oral conditions using survey-weighted multivariable logistic regression. Nationally representative estimates of oral conditions between the PATH Study and NHANES were similar (e.g., ever-experience of bone loss around teeth: PATH Study 15.2%, 95% CI, 14.4%-15.9%; NHANES 16.6%, 95% CI, 14.9%-18.4%). In the PATH Study, combustible tobacco smoking was consistently associated with lifetime and past 12-mo experience of adverse oral health (e.g., exclusive cigarette smoking vs. never tobacco use, adjusted odds ratio [AOR] for loose teeth in past 12 mo: 2.02; 95% CI, 1.52-2.69). Exclusive smokeless tobacco use was associated with greater odds of loose teeth (AOR, 1.93; 95% CI, 1.15-3.26) and lifetime precancerous lesions (AOR, 3.85; 95% CI, 1.73-8.57). Use of other noncigarette products (e.g., pipes) was inconsistently associated with oral health outcomes. PATH Study oral health measures closely align with self-reported measures from NHANES and are internally concurrent. Observed associations with tobacco use and the ability to examine emerging tobacco products support application of PATH Study data in dental research, particularly to examine potential oral health effects of novel tobacco products and longitudinal changes in tobacco use behaviors.

Enhanced decay of coronaviruses in sewers with domestic wastewater

Recent outbreaks caused by coronaviruses and their supposed potential fecal-oral transmission highlight the need for understanding the survival of infectious coronavirus in domestic sewers. To date, the survivability and decay of coronaviruses were predominately studied using small volumes of wastewater (normally 5-30 mL) in vials (in-vial tests). However, real sewers are more complicated than bulk wastewater (wastewater matrix only), in particular the presence of sewer biofilms and different operational conditions. This study investigated the decay of infectious human coronavirus 229E (HCoV-229E) and feline infectious peritonitis virus (FIPV), two typical surrogate coronaviruses, in laboratory-scale reactors mimicking the gravity (GS, gravity-driven sewers) and rising main sewers (RM, pressurized sewers) with and without sewer biofilms. The in-sewer decay of both coronaviruses was greatly enhanced in comparison to those reported in bulk wastewater through in-vial tests. 99% of HCoV-229E and FIPV decayed within 2 h under either GS or RM conditions with biofilms, in contrast to 6-10 h without biofilms. There is limited difference in the decay of HCoV and FIPV in reactors operated as RM or GS, with the T₉₀ and T₉₉ difference of 7-10 min and 14-20 min, respectively. The decay of both coronaviruses in sewer biofilm reactors can be simulated by biphasic first-order kinetic models, with the first-order rate constant 2-4 times higher during the first phase than the second phase. The decay of infectious HCoV and FIPV was significantly faster in the reactors with sewer biofilms than in the reactors without biofilms, suggesting an enhanced decay of these surrogate viruses due to the presence of biofilms and related processes. The mechanism of biofilms in virus adsorption and potential inactivation remains unclear and requires future investigations. The results indicate that the survivability of infectious coronaviruses detected using bulk wastewater overestimated the infectivity risk of coronavirus during wastewater transportations in sewers or the downstream treatment.

Adverse childhood experiences and substance misuse in young people in India: results from the multisite cVEDA cohort

BACKGROUND

Adverse childhood experiences (ACEs) increases vulnerability to externalising disorders such as substance misuse. The study aims to determine the prevalence of ACEs and its association with substance misuse.

METHODS

Data from the Consortium on Vulnerability to Externalising Disorders and Addictions (cVEDA) in India was used (n = 9010). ACEs were evaluated using the World Health Organisation (WHO) Adverse Childhood Experiences International Questionnaire whilst substance misuse was assessed using the WHO Alcohol, Smoking and Substance Involvement Screening Test. A random-effects, two-stage individual patient data meta-analysis explained the associations between ACEs and substance misuse with adjustments for confounders such as sex and family structure.

RESULTS

1 in 2 participants reported child maltreatment ACEs and family level ACEs. Except for sexual abuse, males report more of every individual childhood adversity and are more likely to report misusing substances compared with females (87.3% vs. 12.7%). In adolescents, family level ACEs (adj OR 4.2, 95% CI 1.5-11.7) and collective level ACEs (adj OR 6.6, 95% CI 1.4-31.1) show associations with substance misuse whilst in young adults, child level ACEs such as maltreatment show similar strong associations (adj OR 2.0, 95% CI 1.1-3.5).

CONCLUSION

ACEs such as abuse and domestic violence are strongly associated with substance misuse, most commonly tobacco, in adolescent and young adult males in India. The results suggest enhancing current ACE resilience programmes and 'trauma-informed' approaches to tackling longer-term impact of ACEs in India.

FUNDING

Newton Bhabha Grant jointly funded by the Medical Research Council, UK (MR/N000390/1) and the Indian Council of Medical Research (ICMR/MRC-UK/3/M/2015-NCD-I).

Ethnic minority women’s interactions with antenatal care providers in Europe

Background

Ethnic minority women are at greater risk of maternal morbidity and mortality. Antenatal care reduces risks of adverse maternal and neonatal outcomes and supports a positive transition to motherhood. Important components of quality antenatal care are interactions between women and care providers which are supportive and empowering.

Methods

We conducted a systematic review to identify and synthesise qualitative evidence on ethnic minority women's experiences of accessing antenatal care in European countries. Following a comprehensive search of 8 databases and two-step screening process, we included 27 studies from various European countries. Study findings were coded and synthesised using a ‘best-fit' framework approach.

Findings

Overall women expressed satisfaction with their antenatal care, frequently framed in relation to experiences of maternity care in countries of origin. Women highly valued interactions with antenatal care providers which were supportive and trust-inducing, and when there was continuity of carer to facilitate this. However, studies frequently showed a dichotomy between reported satisfaction with antenatal care and experiences of interactions with care providers which could be discriminatory, stigmatising and disempowering. Some women blamed themselves for negative interactions. Language barriers were frequently identified by women as a factor which hindered their communication with antenatal care providers and the subsequent quality of care received, when suitable interpreters were not available. Negative interactions with antenatal care providers could result in a withdrawal from ongoing antenatal care for some women.

Conclusions

This review highlights the importance of quality interactions between ethnic minority women and antenatal care providers. Policy implications: Antenatal care should be provided in such a way as to facilitate trust, support and effective communication between women and care providers.

Key messages

Positive interactions with care providers form an important element of quality antenatal care for ethnic minority women in Europe. Trust, support and the provision of suitable interpreters, where needed, contribute to positive interactions with antenatal care providers for ethnic minority women in Europe.

Hospital readmissions after catheter ablation for atrial fibrillation among patients with heart failure in the United States

Background

Catheter ablation for atrial fibrillation may improve quality of life and long-term mortality among patients with heart failure.

Purpose

The rates of hospital readmission after catheter ablation for atrial fibrillation among patients with an established diagnosis of heart failure are largely unknown. We aimed to assess the rates and causes of 30-day readmission among patients with heart failure undergoing catheter ablation vs. medical therapy for atrial fibrillation in the United States.

Methods

The 2016 Nationwide Readmissions Database was screened for patients with diagnosis of heart failure and atrial fibrillation using the 10th Revision of International Classification of Diseases codes. Patients undergoing catheter ablation for atrial fibrillation were grouped separately from those treated medically for atrial fibrillation. Thirty-day readmissions were assessed for both groups.

Results

The analytical cohort included 749,776 (national estimate of 1,421,673) patients with heart failure and atrial fibrillation. This included 2,204 patients that underwent catheter ablation. Patients treated with catheter ablation had lower 30-day readmissions compared to the medical therapy group (16.8% vs 20.1%, p&lt;0.001). Fifty-five percent of all readmissions among the catheter ablation cohort were related to cardiac events. Heart failure exacerbation (40%) and arrhythmia (36%) were the most common cardiac causes for readmission after catheter ablation (Figure).

Conclusions

In a contemporary nationwide analysis of patients with heart failure and atrial fibrillation, compared to medical therapy those treated with catheter ablation for atrial fibrillation had fewer 30-day readmissions after index hospital discharge. The most common cause for readmission among patients treated with catheter ablation was heart failure exacerbation and arrhythmia.

Causes of readmission

Funding Acknowledgement

Type of funding source: None

Implications of pacemaker implantation after TAVR: insights from the Nationwide Readmissions Database

Introduction

Conduction disturbances after transcatheter aortic valve replacement (TAVR) requiring permanent pacemaker (PPM) implantation are a well-known procedural complication. Data on the effect of post-TAVR PPM implantation on 30-day readmissions is scarce.

Methods

The Nationwide Readmissions Database (NRD) is a nationally representative sample of all US hospitalizations, representing over 35 million discharges. The 2016 NRD was used to identify patients who underwent TAVR and PPM implantation from January to November 2016. Propensity matching was used to balance baseline clinical characteristics.

Results

Of the 44,607 patients who underwent TAVR, 4,878 (10.9%) required permanent pacemaker implantation during their index hospitalization. Patients requiring PPM during their index admission for TAVR had a higher crude median length of stay (LOS) (5d vs. 3d, p&lt;0.001), median cost of index admission ($61,604 vs. $45,513, p&lt;0.001) and rate of 30-day readmission (14.5% vs 11.2%, p&lt;0.001). After 2:1 propensity matching, PPM patients still had a higher median LOS (5d vs. 3d, p&lt;0.001), median cost of index admission ($61,902 vs. $41,162, p&lt;0.001), and rate of 30-day readmission (13.8% vs 11.1%, p=0.003). Patients who received PPM were more likely to be older (81.1 vs 80.3, OR 1.01, CI 1.01–1.02), diabetic (OR 1.27, 1.13–1.44), obese (OR 1.22, 1.05–1.43), and have right (OR 4.35, 3.72–5.09) or left (OR 1.80, 1.51–2.15) bundle branch blocks on multivariate analysis. Causes of readmission in patients with and without PPM were predominantly non-cardiac (62.9% vs 68.0%). Heart failure was the most common cause of readmission for both groups (18.4% vs 14.6%). Median cost of readmissions ($8716 vs $8250, p=0.34) and LOS (4d vs 4d, p=1) were not significantly different during readmissions.

Conclusions

Based on a nationally representative sample, 10.9% of patients undergoing TAVR required PPM implantation during the index hospitalization. Age, diabetes, obesity, and right or left bundle branch blocks were significant predictors of PPM implantation. PPM implantation resulted in significantly higher LOS, costs, and 30-day readmissions on propensity-matched analysis.

Funding Acknowledgement

Type of funding source: None

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Congenital intestinal malrotation presenting in octogenarians: a report of two cases

Malrotation is part of a spectrum of small and large bowel positional and fixational abnormalities caused by the failure of the fetal intestine to complete a 270-degree rotation around the superior mesenteric artery axis. Rarely, it presents in the adult as a cause of acute small bowel obstruction. Chronic symptoms of malrotation in adults are subtle, and include intermittent abdominal pain, nausea and vomiting. We present two cases of malrotation in octogenarian men presenting acutely with small bowel obstruction. Both patients were treated with emergency surgery. In one case the chronic symptoms resolved postoperatively. Malrotation and midgut volvulus should be considered as a rare differential diagnosis for small bowel obstruction in adults. Suspicions should be increased when there is a history of recurrent presentations with similar symptoms.

Analysis of Pyrrolizidine Alkaloids in Queensland Honey: Using Low Temperature Chromatography to Resolve Stereoisomers and Identify Botanical Sources by UHPLC-MS/MS

Pyrrolizidine alkaloids (PAs) are a diverse group of plant secondary metabolites with known varied toxicity. Consumption of 1,2-unsaturated PAs has been linked to acute and chronic liver damage, carcinogenicity and death, in livestock and humans, making their presence in food of concern to food regulators in Australia and internationally. In this survey, honey samples sourced from markets and shops in Queensland (Australia), were analysed by high-resolution Orbitrap UHPLC-MS/MS for 30 common PAs. Relationships between the occurrence of pyrrolizidine alkaloids and the botanical origin of the honey are essential as pyrrolizidine alkaloid contamination at up to 3300 ng/g were detected. In this study, the predominant alkaloids detected were isomeric PAs, lycopsamine, indicine and intermedine, exhibiting identical MS/MS spectra, along with lesser amounts of each of their N-oxides. Crucially, chromatographic UHPLC conditions were optimised by operation at low temperature (5 °C) to resolve these key isomeric PAs. Such separation of these isomers by UHPLC, enabled the relative proportions of these PAs present in honey to be compared to alkaloid levels in suspect source plants. Overall plant pyrrolizidine alkaloid profiles were compared to those found in honey samples to help identify the most important plants responsible for honey contamination. The native Australian vines of Parsonsia spp. are proposed as a likely contributor to high levels of lycopsamine in many of the honeys surveyed. Botanical origin information such as this, gained via low temperature chromatographic resolution of isomeric PAs, will be very valuable in identifying region of origin for honey samples.

Small bowel obstruction secondary to diaphragmatic herniation following transabdominal cardiac ablation

We report an unusual case of strangulated diaphragmatic hernia secondary to a pericardial ablation, which resulted in necrosis of the incarcerated small bowel. Through a literature search, we have found a limited number of similar cases introducing a case series for this rare but potentially fatal condition.

P6572Sinus arrest post-cardioversion

Introduction

Sinus arrest remains a recognized but likely underreported complication of cardioversion, with incidence ranging widely in the literature, from virtually 0% to 1.5%. After a case of elective cardioversion resulting in the need for ECMO support, we investigated possible risk factors that could help predict adverse outcomes after cardioversion.

Hypothesis

Cardioversion, while generally benign, is not without risks, and further study may help elucidate predictors of morbidity and mortality.

Methods

We retrospectively reviewed data of all patients who underwent cardioversion at three hospitals within the Lifespan health system, Rhode Island Hospital, Newport Hospital, and the Miriam Hospital, between 2000 and 2015. 23 patients who experienced sinus arrest after cardioversion, and characteristics of these patients were compared with those of 3:1 age-and-gender matched controls using binomial logistic regression analysis on Stata.

Results

Of 12,156 patients who underwent cardioversion, 23 patients (57% male, mean age 78±14), or 0.18%, experienced immediate post-cardioversion sinus arrest, defined as absence of sinus activity for greater than five seconds. Compared with 3:1 age-and-gender-matched controls who underwent cardioversion without incident, binomial logistic regression revealed that paroxysmal atrial fibrillation (OR 11.8; 95% CI 1.85–75.72; p=0.009), beta-blocker use (OR 58.0; 95% CI 2.4–1404.48; p=0.013), Amiodarone use (OR 19.9; 95% CI 2.0–198.32; p=0.011), and elevated ventricular rate (CV 0.028; 95% CI 0.0031–0.053; p=0.027) were statistically significant predictors of sinus arrest after cardioversion. Calcium-channel blocker use, Digoxin use, age, gender, PR interval, QRS duration, and corrected QT interval were not significant associations.

Conclusions

Sparse data exists regarding characteristics predisposing patients to adverse outcomes following cardioversion, and further risk stratification is warranted, given the potential for significant morbidity and mortality. Our findings raise questions that demand elucidation, such as whether beta-blockers or Amiodarone should be held prior to cardioversion.

Engineered Protein Polymer-Gold Nanoparticle Hybrid Materials for Small Molecule Delivery

We have fabricated protein polymer-gold nanoparticle (P-GNP) nanocomposites that exhibit enhanced binding and delivery properties of the small hydrophobic molecule drug, curcumin, to the model breast cancer cell line, MCF-7. These hybrid biomaterials are constructed via in situ GNP templated-synthesis with genetically engineered histidine tags. The P-GNP nanocomposites exhibit enhanced small molecule loading, sustained release and increased uptake by MCF-7 cells. When compared to the proteins polymers alone, the P-GNPs demonstrate a greater than 7-fold increase in curcumin binding, a nearly 50% slower release profile and more than 2-fold increase in cellular uptake of curcumin. These results suggest that P-GNP nanocomposites serve as promising candidates for drug delivery vehicles.

Indigenous rangeland resource management in the mountainous areas of northern Nepal: a case study from the Rasuwa District

Rangelands perform numerous functions that have significant ecological and livelihood values for mountain societies in Nepal. There are no other systems more suitable than indigenous management systems, which have evolved over long periods of time and offer approaches to land use that are suitable to the varying climatic, biophysical conditions and ethnic diversity that characterise Nepal. However, traditional resource management practices have been ignored in the past, which has resulted in conflicts and resource degradation. In this context, a survey was conducted in the Rasuwa District of northern Nepal to identify existing indigenous rangeland management systems, examine the challenges facing the development of sustainable practices and suggest possible strategies for promoting their development. It was concluded from this study that local herders in the Rasuwa District of northern Nepal have developed effective indigenous rangeland management systems that include good grazing and conservation practices. Well organised local institutional arrangements and efficient traditional right and tenure systems have evolved that result in the sustainable use of rangeland resources. However, both internal and external factors are now challenging these traditional systems. Results indicated that to remain sustainable rangeland management systems in northern Nepal will require a clear recognition of indigenous knowledge of rangeland management as well as the integration of indigenous practices and strategies with modern technologies. More attention should be paid to the facilitation of rangeland legislation covering traditional rights and customary tenure, institutional cooperation and collaboration between government and civil society. Co-management and participatory research and development should be initiated on rangeland resources and the improvement of infrastructure and public service systems.

Recombinant erythropoietin and blood transfusion in selected preterm infants

OBJECTIVES

To comprehensively identify preterm infants likely to require blood transfusion and to investigate the effectiveness of recombinant erythropoietin in this high risk subgroup.

DESIGN

Double blind randomised controlled trial.

SETTING

Neonatal Intensive Care Unit, Middlemore Hospital, Auckland, New Zealand.

PATIENTS

Preterm infants < 33 weeks gestation and < 1700 g birth weight meeting specific criteria indicating a high possibility of requiring blood transfusion.

INTERVENTIONS

Predictors of blood transfusion were determined by analysis of preterm infants admitted to a neonatal intensive care unit over a two year period. Using the criteria developed, high risk infants entered the study and received erythropoietin or sham treatment until 34 weeks completed gestation. The sample size was calculated to detect a reduction of one blood transfusion per infant (significance level 5%, power 80%).

RESULTS

The selection criteria had a positive predictive value for transfusion of 91% and a negative predictive value of 94%. Mean birth weights and gestational ages were similar in the two groups. Absolute reticulocyte counts and haemoglobin values were higher in the group receiving erythropoietin. There was no significant difference in the number of blood transfusions received in the treatment and control groups. However, comparing transfusions given to < 1000 g infants after 30 days of age, there were significantly fewer transfusions in the erythropoietin group (mean (SD) 0.5 (0.7) in those receiving erythropoietin and 1.6 (1.1) in the controls). No adverse effects were noted.

CONCLUSIONS

The selection criteria for the study were highly predictive of subsequent transfusion. In the group receiving erythropoietin, a reduction in transfusion requirements was apparent only in the < 1000 g birthweight group after 1 month of age.

Supracostal approach in percutaneous nephrolithotomy: experience with 102 cases

PURPOSE

To assess retrospectively the safety and efficacy of the supracostal approach in percutaneous nephrolithotomy (PCNL).

PATIENTS AND METHODS

Among 862 patients who underwent PCNL between April 1986 and December 1999, supracostal puncture was performed in 102. Their stones were either solitary (66.5%), multiple (15.7%), or staghorn (19.6%). Upper ureteral calculi were the commonest indication (32.4%). The interspace between the 11th and 12th ribs was used in all cases. After tract dilatation with telescopic metal dilators, pneumatic or ultrasound lithotripsy was used for fragmentation.

RESULTS

Complete clearance was achieved in 79.5%. Ten patients (9.8%) had pleural violation in the form of hydrothorax, pneumothorax, or hydropneumothorax. All of these patients were managed successfully by intercostal chest tube drainage.

CONCLUSION

Supracostal puncture in a safe and effective approach with acceptable morbidity in selected cases of staghorn, upper ureteral, and upper caliceal calculi.

Soil, water and nutrient conservation in mountain farming systems: case-study from the Sikkim Himalaya

The Khanikhola watershed in Sikkim is agrarian with about 50% area under rain-fed agriculture representing the conditions of the middle mountains all over the Himalaya. The study was conducted to assess overland flow, soil loss and subsequent nutrient losses from different land uses in the watershed, and identify biotechnological inputs for management of mountain farming systems. Overland flow, soil and nutrient losses were very high from open agricultural (cropped) fields compared to other land uses, and more than 72% of nutrient losses were attributable to agriculture land use. Forests and large cardamom agroforestry conserved more soil compared to other land uses. Interventions, like cultivation of broom grass upon terrace risers, N2-fixing Albizia trees for maintenance of soil fertility and plantation of horticulture trees, have reduced the soil loss (by 22%). Soil and water conservation values (> 80%) of both large cardamom and broom grass were higher compared to other crops. Use of N2-fixing Albizia tree in large cardamom agroforestry and croplands contributed to soil fertility, and increased productivity and yield. Bio-composting of farm resources ensured increase in nutrient availability specially phosphorus in cropped areas. Agricultural practices in mountain areas should be strengthened with more agroforestry components, and cash crops like large cardamom and broom grass in agroforestry provide high economic return and are hydroecologically sustainable.

STEP61: a member of a family of brain-enriched PTPs is localized to the endoplasmic reticulum

The STEP family of protein tyrosine phosphatases is highly enriched within the CNS. Members of this family are alternatively spliced to produce both transmembrane and cytosolic variants. This manuscript describes the distinctive intracellular distribution and enzymatic activity of the membrane-associated isoform STEP61. Transfection experiments in fibroblasts, as well as subcellular fractionations, sucrose density gradients, immunocytochemical labeling, and electron microscopy in brain tissue, show that STEP61 is an intrinsic membrane protein of striatal neurons and is associated with the endoplasmic reticulum. In addition, structural analysis of the novel N-terminal region of STEP61 reveals several motifs not present in the cytosolic variant STEP46. These include two putative transmembrane domains, two sequences rich in Pro, Glu, Asp, Ser, and Thr (PEST sequences), and two polyproline-rich domains. Like STEP46, STEP61 is enriched in the brain, but the recombinant protein has less enzymatic activity than STEP46. Because STEP46 is contained in its entirety within STEP61 and differs only in the extended N terminus of STEP61, this amino acid sequence is responsible for the association of STEP61 with membrane compartments and may also regulate its enzymatic activity.

Identification of two alternatively spliced transcripts of STEP: a subfamily of brain-enriched protein tyrosine phosphatases

A brain-enriched protein tyrosine phosphatase termed STEP46 (striatal enriched phosphatase) was previously isolated and characterized. Immunological studies with a STEP monoclonal antibody recognized several STEP-immunoreactive proteins, and suggested that additional STEP-related polypeptides existed. This study reports the isolation of two alternatively spliced transcripts of the STEP gene. One of these, STEP20 (with a predicted molecular mass of 20 kDa) was further characterized and found to lack the conserved tyrosine phosphatase domain. Northern analysis detected a 2.8 kb STEP20 message in mouse brain. The second alternatively spliced transcript, STEP61, has a 5'-extended open reading frame that encodes a protein with a predicted molecular mass of 61 kDa and contains a single tyrosine phosphatase domain. The exon-intron organization responsible for the novel STEP20 and STEP61 sequences was determined in the mouse STEP genomic DNA. We propose that the original STEP46, along with STEP20 and STEP61, are members of a brain-enriched subfamily of protein tyrosine phosphatases, and that STEP isoforms may have distinct functions within the central nervous system.

A neuronal protein tyrosine phosphatase induced by nerve growth factor

A new protein tyrosine phosphatase (PC12-PTP1) was identified in nerve growth factor (NGF)-treated PC12 cells. The mRNA level of PC12-PTP1 is increased 9-fold over the initial 8 h of NGF treatment and then decreases dramatically after 24 h of treatment. In rat brain, three transcripts corresponding to 1.5, 2.6, and 3.0 kilobases (kb) in size are detected by Northern blot analysis. Although the 1.5- and 2.6-kb transcripts are present in brain and other tissues, the 3-kb transcript is exclusively expressed in brain and the expression of this transcript alone increases following NGF treatment. PC12-PTP1 is a non-receptor protein tyrosine phosphatase (PTP) with a 50% sequence homology in the phosphatase domain with several other non-receptor PTPs. PC12-PTP1 fusion protein exhibits tyrosine phosphatase activity, and in vitro translation of the PC12-PTP1 transcript produces a major protein of 39 kDa. The data presented suggest that NGF regulates the expression of PC12-PTP1 during periods of neuronal growth and differentiation.

Stemflow: A Source of Nutrients in some Naturally Growing Epiphytic Orchids of the Sikkim Himalaya

A study on five naturally growing epiphytic orchids viz., Bulbophyllum affine Lindl., Coelogyne ochracea Lindl., Otochilus porrecta Lindl., Cirrhopetalum cornutum Lindl. and C. cornutum (var.) was carried out in the subtropical belt of Sikkim Himalaya. Stemflow leachates formed the main source of ammonium-N and nitrate-N for uptake by these orchids. Phosphorus concentration in the tissues of these orchids was high. Phosphate-P from stemflow does not seem to be a regular source of phosphorus for these orchids. Absorption/desorption results indicate that organic-N from stemflow leachates is not utilized by these orchids.

Adenovirus 12-mediated down-regulation of the major histocompatibility complex (MHC) class I promoter: identification of a negative regulatory element responsive to Ad12 E1A

In highly oncogenic adenovirus (Ad) 12-transformed cells, major histocompatibility complex (MHC) class I gene expression is down-regulated by the products of the viral E1A oncogene at the level of initiation of transcription. However, class I gene expression is unaltered or elevated in non-oncogenic Ad2- or Ad5-transformed cells. These changes in class I expression may permit Ad12-transformed cells to escape host immune surveillance and elicit tumour formation. Here we show that the 2kb of 5' flanking region of the mouse H-2Kb class I gene is sufficient to mediate down-regulation of transcription driven from homologous or heterologous (HSV thymidine kinase) basal promoter elements in cells expressing Ad12 E1A, but not in Ad2 E1A-expressing cells. Deletion analysis of the 2kb region showed that sequences from -1.18 to -1.44kb (relative to the cap site) were a target for Ad12 E1A-mediated transcriptional down-regulation. Deletion of this entire region from the 2kb flanking sequence of the H-2Kb gene abolished Ad12 E1A-mediated down-regulation of transcription. Computer analysis of the -1.18 to -1.44kb sequence identified two 6/7bp matches with the AP-1 transcription factor consensus sequence and two matches with the pig MHC class I PD1 repressor element. Gel retardation analysis using overlapping DNA fragments derived from the -1.18 to -1.44kb sequence revealed several DNA:protein complexes formed using nuclear extract derived from Ad12-, but not from Ad2- or Ad5-transformed cells. Some of these DNA:protein complexes were also present, but at lower levels, in nuclear extracts from untransformed rat cells suggesting the possible involvement of cellular factors in the mechanism of down-regulation mediated by Ad12 E1A. A binding site for the AP-1 factor failed to compete for protein binding to fragments within the -1.18 to -1.44 sequence, while the PD1 site competed for binding only in the -1.15 to -1.23 region. These results indicate that novel factors (as well as a previously identified class I repressor, PD1) may be involved in Ad12 E1A-mediated down-regulation of MHC class I transcription.

A protein tyrosine phosphatase expressed within dopaminoceptive neurons of the basal ganglia and related structures

Immunocytochemical and biochemical studies were conducted to characterize a brain-specific protein tyrosine phosphatase, designated STEP for striatal enriched phosphatase. STEP immunoreactivity was most intense in select regions of the CNS receiving a dopaminergic input, and was localized to cell bodies, dendrites, and axonal processes. Western blot analyses of rat brain homogenates revealed a triplet of polypeptides with relative mobilities (M(r)) of 46 kDa, 37 kDa, and 33 kDa enriched within the striatum. Phase separation of protein homogenates by Triton X-114 extraction indicated that this triplet was enriched in soluble but not membrane fractions. Affinity-purified STEP fusion protein exhibited phosphatase activity while a mutated form of the STEP fusion protein (Cys300Ser) showed no demonstrable phosphatase activity.

Molecular analysis of the recA gene of Agrobacterium tumefaciens C58

The complete nucleotide sequence of the Agrobacterium tumefaciens recA gene was determined. A comparison of the translated open reading frame of the gene with other known recA sequences revealed significant sequence conservation. However, unlike its Escherichia coli equivalent, A. tumefaciens recA lacks the upstream 'SOS box', suggesting a different mechanism of regulation for this gene.

Protein growth factor(s) from C6 glioma cells that promote the growth of murine hybridomas

C6 glioma cell conditioned medium (C6CM) has been used as a growth supplement for murine hybridomas. At 10% C6CM has been found to increase cell proliferation by 3-4-fold. This effect is observed in the presence of saturating concentration of FCS. Clonal growth is also enhanced 6.7-fold. No growth promoting effect is seen on murine myelomas or spleen cells. The factor(s) appear to be protein in nature.

Expression of a marrow stroma and thymus-associated antigen (ST3) in the rat brain: comparison with Thy-1

Cells of the immunohemopoietic and nervous systems express certain molecules that generally are not found in other tissues. One example is the 'ST3' antigen, which is present on the major population of fibroblastoid cells grown from rat bone marrow, but is not detected on adherent cells from most peripheral organs (e.g. lung). An immunohistological survey revealed ST3 also in the thymic cortex, the glomerular mesangial area, and the brain. Because this pattern of distribution is similar to that described for Thy-1, we compared the localization of the two antigens in the adult rat brain and found that there were areas where it was congruent and others where it was distinct. Staining for ST3 was absent from the white matter, but was especially notable in discrete layers of the frontal, orbital, parietal, and cingulate cortices, the substantia nigra, the inferior olivary nuclei, and the deep molecular layer of the cerebellum, as well as other scattered regions in the gray matter. This is in contrast to Thy-1, which stained more diffusely throughout the gray zones. In further experiments using primary brain cell cultures, ST3 was demonstrated on neurons, but not on oligodendrocytes or astrocytes. Similarly, it was found on the surface of cells of the PC12 neuronal line, but not on the C6 astrocytoma. This restricted distribution on a subpopulation of neurons raises the possibility that the ST3 epitope might be part of a cell interaction molecule of the marrow stroma, thymus, and brain.

Exact ray paths in bent waveguides

We present here the Lagrangian formalism for studying the ray paths in cylindrically symmetric media. We have used the analysis to obtain the exact ray paths in bent slabs as well as in bent fibers with a separable profile.