Investigation of fire regime dynamics and modeling of burn area over India for the twenty-first century

The characteristics of the vegetation fire (VF) regime are strongly influenced by geographical variables such as regional physiographic settings, location, and climate. Understanding the VF regime is extremely important for managing and mitigating the impacts of fires on ecosystems, communities, and human activities in forest fire-prone regions. The present study thereby aimed to explore the potential effects of the confounding factors on VF in India to offer actionable and achievable solutions for mitigating this concurring environmental issue sustainably. A global burn area (250 m) data (Fire-CCIv5.1) and fire radiative power (FRP) were used to investigate the dynamics of VF across seven different divisions in India. The study also used the maximum and minimum temperatures, precipitation, population density, and intensity of human modification to model forest burn areas (including grassland). The Coupled Model Intercomparison Project-6 (CMIP6) was used to predict the burn area for 2030 and 2050 future climate scenarios. The present study accounted for a sizable increasing trend of VF during 2001-2019 period. The highest increasing trend was found in central India (513 and 343 km2 year-1 in the forest and crop fire, respectively), followed by southern India (364 km2 year-1 in forest fire), and upper Indo-Gangetic plain (128 km2 year-1 in crop fire). The FRP has varied significantly across the divisions, with the north-eastern Himalayas exhibiting the highest FRP hotspot. The maximum and minimum temperatures have the greatest influence on forest fires, according to Random Forest (RF) modeling. The estimated pre-monsoonal burn area for 2050 and 2050 future scenarios suggested a more frequent forest fire occurrence across India, particularly in southern and central India. A comprehensive forest fire control policy is therefore essential to safeguard and conserve forest cover in the regions, affected by forest fire periodically.

Multi-omics analysis identifies potential microbial and metabolite diagnostic biomarkers of bacterial vaginosis

BACKGROUND

Bacterial vaginosis (BV) is a common clinical manifestation of a perturbed vaginal ecology associated with adverse sexual and reproductive health outcomes if left untreated. The existing diagnostic modalities are either cumbersome or require skilled expertise, warranting alternate tests. Application of machine-learning tools to heterogeneous and high-dimensional multi-omics datasets finds promising potential in data integration and may aid biomarker discovery.

OBJECTIVES

The present study aimed to evaluate the potential of the microbiome and metabolome-derived biomarkers in BV diagnosis. Interpretable machine-learning algorithms were used to evaluate the utility of an integrated-omics-derived classification model.

METHODS

Vaginal samples obtained from reproductive-age group women with (n = 40) and without BV (n = 40) were subjected to 16S rRNA amplicon sequencing and LC-MS-based metabolomics. The vaginal microbiome and metabolome were characterized, and machine-learning analysis was performed to build a classification model using biomarkers with the highest diagnostic accuracy.

RESULTS

Microbiome-based diagnostic model exhibited a ROC-AUC (10-fold CV) of 0.84 ± 0.21 and accuracy of 0.79 ± 0.18, and important features were Aerococcus spp., Mycoplasma hominis, Sneathia spp., Lactobacillus spp., Prevotella spp., Gardnerella spp. and Fannyhessea vaginae. The metabolome-derived model displayed superior performance with a ROC-AUC of 0.97 ± 0.07 and an accuracy of 0.92 ± 0.08. Beta-leucine, methylimidazole acetaldehyde, dimethylethanolamine, L-arginine and beta cortol were among key predictive metabolites for BV. A predictive model combining both microbial and metabolite features exhibited a high ROC-AUC of 0.97 ± 0.07 and accuracy of 0.94 ± 0.08 with diagnostic performance only slightly superior to the metabolite-based model.

CONCLUSION

Application of machine-learning tools to multi-omics datasets aid biomarker discovery with high predictive performance. Metabolome-derived classification models were observed to have superior diagnostic performance in predicting BV than microbiome-based biomarkers.

Energy inequality and air pollution nexus in India

Energy usage, inequality, and their impacts are deeply intertwined, especially in India. Every year, cooking using biomass-based solid fuel usage causes death to tens of thousands of Indians, specifically, economically unprivileged people. Solid fuel burning has been known as one of the prominent sources of ambient PM_2.5 (particulate matter with an aerodynamic diameter of <2.5 μm) concentration in the atmosphere. Thus, limiting the PM_2.5 emission from biomass-based cooking fuel through the transition to LPG has gained priority. The government report in India indicates that nearly 8 million households became beneficiaries of the LPG connection through the PMUY scheme till 2019. The transition to clean cooking fuel may have an influence on the ambient PM_2.5 concentration. In this study, to explore the nexus between energy inequality and air pollution, we investigated the present status of clean fuel usage in India and its drivers, including the impact of such a massive transition to cleaner fuel on ambient air quality, with a specific focus on PM_2.5. The results show an improvement of 15 % in LPG usage from 2015 to 2019 in India., Yet the majority of poorer (>60 %) and poorest communities (>90 %) still use solid biomass as the cooking fuel. No significant correlation (r = 0.036; p-value ≫ 0.05) was obtained between LPG usage and ambient PM_2.5 concentration suggesting the influence of other confounding factors which might subdue the anticipated effect of the usage of clean fuel. The analysis suggests, despite the successful launching of the PMUY, the low LPG usage pattern among the poor, because of the lack of an effective subsidy policy, might jeopardize the effort to fix the standard of ambient air as per WHO.

Antimicrobial resistance in bacteria isolated from the poultry production system in Nepal

SETTING

Twenty poultry farms in five provinces of Nepal were selected for studying bacterial pathogens and their antimicrobial resistance (AMR) patterns.

OBJECTIVE

To document the proportion of cloacal swabs collected from 3,230 broiler and 3,230 layer chickens from September to December 2021 that grew isolates of Escherichia coli, Enterococcus spp. and Salmonella spp. along with their AMR patterns.

DESIGN

This was a cross-sectional descriptive study.

RESULTS

In broiler birds, Enterococcus spp., Salmonella spp. and E. coli were identified in respectively 36%, 39% and 63% of swabs. In layer birds, Enterococcus spp., Salmonella spp. and E. coli were identified in respectively 31%, 48% and 60% of swabs. For both bird types, there was variation in bacterial prevalence between the regions. For all three bacterial isolates, the lowest antimicrobial resistance was found with amikacin. For the other nine antibiotics tested, >50% of bacterial isolates showed resistance; between 60% and 90% of isolates showed resistance to ciprofloxacin and trimethoprim-sulfamethoxazole. Multidrug resistance ranged from 45% to 46% for Salmonella spp., 37-44% for E. coli and 13-17% for Enterococcus spp.

CONCLUSION

This study shows that a large proportion of poultry in Nepal are infected with potentially pathogenic bacteria, and these are frequently resistant to commonly used antibiotics. Nepal urgently needs to implement corrective measures.

Early second-trimester three-dimensional transvaginal neurosonography of fetal midbrain and hindbrain: normative data and technical aspects

OBJECTIVES

To provide a detailed description of the sonographic appearance and development of various fetal structures of the midbrain and hindbrain (MBHB) during the early second trimester, and to evaluate the impact of the frequency of the transvaginal sonography (TVS) transducer on the early recognition of these structures.

METHODS

This was a retrospective analysis of three-dimensional volumetric datasets of the MBHB from apparently normal fetuses at 14-19 gestational weeks, acquired by TVS in the midsagittal view through the posterior fontanelle. Using a multiplanar approach, we measured the tectal thickness and length, aqueductal thickness, tegmental thickness and width and height of the Blake's pouch (BP) neck. In addition, we assessed the existence of early vermian fissures, the linear shape of the brainstem and the components of the fastigium. The correlation between gestational age according to last menstrual period and sonographic measurements of MBHB structures was evaluated using Pearson's correlation (r). A subanalysis was performed to assess the performance of a 5-9-MHz vs a 6-12-MHz TVS transducer in visualizing the MBHB structures in the early second trimester.

RESULTS

Sixty brain volumes were included in the study, obtained at a mean gestational age of 16.2 weeks (range, 14.1-19.0 weeks), with a transverse cerebellar diameter range of 13.0-19.8 mm. We found a strong correlation between gestational age and all MBHB measurements, with the exception of the tectal, tegmental and aqueductal thicknesses, for which the correlation was moderate. There was good-to-excellent intraobserver and moderate-to-good interobserver correlation for most MBHB measurements. We observed that the BP neck was patent in all fetuses between 14 and 18 weeks with decreasing diameter, and that the aqueductal thickness was significantly smaller at ≥ 18 weeks compared with at < 16 weeks. The early vermian fissures and the linear shape of the brainstem were present in all fetuses from 14 weeks. We found that, in the early second trimester, the horizontal arm of the presumed 'fastigium' evolves from the fourth ventricular choroid plexus and not the posterior vermis, indicating that this is not the fastigium. Standard- and high-resolution TVS transducers performed similarly in the assessment of MBHB anatomy.

CONCLUSION

Detailed early second-trimester assessment of the MBHB is feasible by transvaginal neurosonography and provides reference data which may help in the early detection of brain pathology involving the MBHB. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Water quality assessment of the Ganges River during COVID-19 lockdown

Ganges River water quality was assessed to record the changes due to the nation-wide pandemic lockdown. Satellite-based (Sentinel-2) water quality analysis before and during lockdown was performed for seven selected locations spread across the entire stretch of the Ganges (Rishikesh-Dimond Harbour). Results revealed that due to the lockdown, the water quality of the Ganges improved with reference to specific water quality parameters, but the improvements were region specific. Along the entire stretch of Ganges, only the Haridwar site showed improvement to an extent of being potable as per the threshold set by the Central Pollution Control Board, New Delhi, India. A 55% decline in turbidity at that site during the lockdown was attributed to the abrupt halt in pilgrimage activities. Absorption by chromophoric dissolved organic matter which is an indicator of organic pollution declined all along the Ganges stretch with a maximum decline at the downstream location of Diamond Harbour. Restricted discharge of industrial effluent, urban pollution, sewage from hotels, lodges, and spiritual dwellings along the Ganges are some of the reasons behind such declines. No significant change in the geographic trend of chlorophyll-a was observed. The findings of this study highlight the importance of regular monitoring of the changes in the Ganges water quality using Sentinel-2 data to further isolate the anthropogenic impact, as India continues the phase-wise opening amidst the pandemic.

Revisiting the levels of Aerosol Optical Depth in south-southeast Asia, Europe and USA amid the COVID-19 pandemic using satellite observations

The countries around the world are dealing with air quality issues for decades due to their mode of production and energy usages. The outbreak of COVID-19 as a pandemic and consequent global economic shutdown, for the first time, provided a base for the real-time experiment of the effect of reduced emissions across the globe in abetting the air pollution issue. The present study dealt with the changes in Aerosol Optical Depth (AOD), a marker of air pollution, because of global economic shutdown due to the coronavirus pandemic. The study considered the countries in south and south-east Asia (SSEA), Europe and the USA for their extended period of lockdown due to coronavirus pandemic. Daily Aerosol Optical Depth (AOD) from Moderate-resolution imaging spectroradiometer (MODIS) and tropospheric column density of NO₂ and SO₂ from Ozone monitoring instrument (OMI) sensors, including meteorological data such as wind speed (WS) and relative humidity (RH) were analyzed during the pre-lockdown (2017-2019) and lockdown periods (2020). The average AOD, NO₂ and SO₂ during the lockdown period were statistically compared with their pre-lockdown average using Wilcoxon-signed-paired-rank test. The accuracy of the MODIS-derived AOD, including the changing pattern of AOD due to lockdown was estimated using AERONET data. The weekly anomaly of AOD, NO₂ and SO₂ was used for analyzing the space-time variation of aerosol load as restrictions were imposed by the concerned countries at the different points of time. Additionally, a random forest-based regression (RF) model was used to examine the effects of meteorological and emission parameters on the spatial variation of AOD. A significant reduction of AOD (-20%) was obtained for majority of the areas in SSEA, Europe and USA during the lockdown period. Yet, the clusters of increased AOD (30-60%) was obtained in the south-east part of SSEA, the western part of Europe and US regions. NO₂ reductions were measured up to 20-40%, while SO₂ emission increased up to 30% for a majority of areas in these regions. A notable space-time variation was observed in weekly anomaly. We found the evidence of the formation of new particles for causing high AOD under high RH and low WS, aided by the downward vertical wind flow. The RF model showed a distinguishable relative importance of emission and meteorological factors among these regions to account for the spatial variability of AOD. Our findings suggest that the continued lockdown might provide a temporary solution to air pollution; however, to combat persistent air quality issues, it needs switching over to the cleaner mode of production and energy. The findings of this study, thus, advocated for alternative energy policy at the global scale.

All cause 30 readmission in patients with history of sudden cardiac arrest

Background

Sudden cardiac arrest (SCA) remains a significant cause of morbidity and mortality. Current evidence on readmission rates and causes after SCA are scarce.

Purpose

To describe patient characteristics, predictors of readmission and outcomes patients with history of sudden cardiac arrest and 30-day readmission

Methods

We analyzed the National Readmission Database for years 2016 and 2017 to identify all patients with initial diagnosis of SCA and 30 days readmission after the initial event. We analyzed baseline characteristics and looked into predictors, outcomes and diagnoses of re-admission.

Results

We identified 79,844 patients with an initial diagnosis of SCA that were discharged alive after index admission. Of those 14,387 (18.01%) had one readmission and 3,978 (4.99%) had more than one readmission. The mean age was 64 years and 41.3% were females. Hypertension, dyslipidemia, diabetes, CAD, CHF and CKD were present in 76.5%, 42.4%, 46.3%, 50.4%, 62.3% and 43.5% respectively. Overall mortality was 9.1% and length of stay 7.8 days. (Table 1). Congestive heart failure was the predominant diagnosis for readmission (Figure). Female sex (HR=0.93; p=0.004) was the only independent risk factor for all cause readmission.

Conclusions

Patients with history of SCA that have a 30-day readmission have significantly more comorbidities and length of day. Congestive heart failure is the predominant diagnosis for readmission

Funding Acknowledgement

Type of funding source: None

Higher rates of early initiation of breastfeeding associated with health facility delivery in Nepal

Background

Initiation of breastfeeding within one hour from birth is one of the five key essential newborn care messages, implemented along with birth preparedness package since 2008. This study aimed to determine the trend of early initiation of breastfeeding (EIBF) and to assess the effect of health facility delivery on EIBF in Nepal.

Methods

We analyzed the data from the last four nationally representative Nepal Demographic and Health Surveys (NDHS) conducted in 2001,2006,2011 and 2016. Data on the early initiation of breastfeeding was obtained from the mothers of infants born within 24 months prior to the survey. The explanatory variable was the place of delivery, dichotomized as either the health facility, or home delivery. Survey year had a significant interaction with the place of delivery. Multivariable logistic regression was conducted separately on pooled samples before (NDHS 2001 and 2006) and after (NDHS 2011 and 2016) the program implementation. Adjusted odds ratio (AOR) with 95% confidence interval (CI) for EIBF was calculated after adjusting for predetermined covariates.

Results

The rate of EIBF increased by 26.5% points (from 32.8% in 2001 to 59.3% in 2016) among infants delivered in a health facility, compared to an increase by 17.1% points (from 29.9% to 47.0%) among home born infants. EIBF increased by 32.5% points before, compared to 49.7% points after BPP. Delivery in a health facility was associated with a higher odd of EIBF in later years (AOR2.3, 95% CI 2.0,2.8), but not in earlier years (AOR1.3, 95% CI 0.9,2.0). Delivery by caesarean section, first-born infant, and lack of maternal education were associated with a lower rate of EIBF in both periods.

Conclusions

Higher EIBF was associated with health facility delivery in Nepal, only after programmatic emphasis on essential newborn care messages. This implies the need for explicit focus on EIBF at birth, particularly when mother is less educated, primiparous or undergoing operative delivery.

Key messages

The rate of initiation of breastfeeding within an hour from birth is increasing in Nepal, with higher rates in health facility delivery, as shown by the recent four nationally representative surveys. Programmatic focus on essential newborn care messages may have contributed to significant association of higher rates of early initiation of breastfeeding when delivered in health facility.

Charge regulation of a surface immersed in an electrolyte solution

In this paper, we investigate theoretically a model of charge regulation of a single charged planar surface immersed in an aqueous electrolyte solution. Assuming that the adsorbed ions are mobile in the charged plane, we formulate a field theory of charge regulation where the numbers of adsorbed ions can be determined consistently by equating the chemical potentials of the adsorbed ions to that of the ions in the bulk. We analyze the mean-field treatment of the model for electrolyte of arbitrary valences, and then beyond, where correlation effects are systematically taken into account in a loop expansion. In particular, we compute exactly various one-loop quantities, including electrostatic potentials, ion distributions, and chemical potentials, not only for symmetric (1, 1) electrolyte but also for asymmetric (2, 1) electrolyte, and make use of these quantities to address charge regulation at the one-loop level. We find that correlation effects give rise to various phase transitions in the adsorption of ions, and present phase diagrams for (1, 1) and (2, 1) electrolytes, whose distinct behaviors suggest that charge regulation, at the one-loop level, is no longer universal but depends crucially on the valency of the ions.

Artificial intelligence in dermatology: the "unsupervised" learning

The potential areas of application of artificial intelligence in dermatology are ever-increasing. With the wide availability of smartphones equipped with high-resolution cameras and impressive processing powers, harnessing these capabilities using machine learning (ML) could open new prospects in the management of dermatological disorders. Du-Harpur et al. have done a commendable job reviewing the utility of artificial intelligence in dermatology in an easily understandable manner by most dermatologists1 .

Trichoscopy of primary cicatricial alopecias: an updated review

Trichoscopy is an emerging technique for the evaluation of various hair and scalp disorders including primary cicatricial alopecias (PCAs). Early diagnosis of PCAs can lead to effective management and trichoscopy could be a useful aid during this process. Multiple studies have reported the trichoscopic features of PCAs, however, a focused review evaluating these disorders with their trichoscopic features is lacking. With the objective of evaluating the trichoscopic findings reported in the literature for various PCAs, we conducted a systematic literature search in PubMed and Embase. The search yielded 310 studies in a total of which 54 studies were included in our review. Majority of these studies originated from the Caucasian or Asian population. Through this review, we provide an overview of the frequent and specific trichoscopic findings in different PCAs with their clinical significance where applicable based on the current knowledge and identify the areas for future research.

Characterisation of emission from open-field burning of crop residue during harvesting period in north-west India

Open-field crop residue burning is one of the important sources of atmospheric pollution in north-west India during the harvesting period. In this work, we studied NO₂ and SO₂ concentrations and physical and chemical properties of aerosols from open-field combustion of rice and wheat residue. NO₂ and SO₂ were analysed using UV-spectrophotometer and ion chromatography (IC) respectively. The aerosol particles were analysed by scan electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX) for their physical dimension (size distribution) and elemental composition, and by IC for their ionic content. The measured concentrations of gases during burning showed rice straw burning spews more NO₂ and SO₂ than wheat straw burning. The calculated size of the particles ranged from 0.26 to 151.09 μm with high standard deviation. The median diameter of 1.64 μm (± 6.9) represented the central tendency of the particles emitted due to this combustion process. Comparative content analysis revealed that rice-borne particles are richer in Na, K, Al, Si and Zn, whereas, wheat-borne particles are more abundant in C, Mg, Fe, P and Cl. The results from IC and SEM-EDX evidenced the presence of fluoride, sulphate, carbonate, chloride, oxides and silicate compounds in particles. The emission of greenhouse gases (GHGs) and aerosols with this particle chemistry increases the atmospheric opacity through the absorption and scattering of incoming radiation at a significant amount in the UV-IR range causing high aerosol optical depth (AOD).

Hypocalcemia and bone mineral density changes following denosumab treatment in end-stage renal disease patients: a meta-analysis of observational studies

The incidence of hypocalcemia and bone mineral density (BMD) changes in end-stage renal disease (ESRD) patients on denosumab remains unclear. We performed this meta-analysis to assess the incidence of denosumab-associated hypocalcemia and effects of denosumab on BMD in ESRD patients. A literature search was conducted using MEDLINE, EMBASE, and Cochrane Database from inception through November 2017 to identify studies evaluating incidence of denosumab-associated hypocalcemia and changes in serum calcium, phosphate, alkaline phosphatase (ALP), parathyroid hormone (PTH), and BMD from baseline to post-treatment course of denosumab in ESRD patients. Study results were pooled and analyzed using a random-effect model. The protocol for this meta-analysis is registered with PROSPERO (International Prospective Register of Systematic Reviews; no. CRD42017081074). Six observational studies with a total of 84 ESRD patients were enrolled. The pooled estimated incidence of hypocalcemia during denosumab treatment was 42% (95% CI 29-55%, I² = 0%). Hypocalcemia occurred approximately 7 to 20 days after the first dose and reached nadir of low calcium levels in the first 2 weeks up to 2 months. However, there were no significant changes in serum calcium or phosphate from baseline to post-treatment course (≥ 3 months after treatment) with mean differences [MDs] of 0.20 mg/dL (95% CI, - 0.30 to 0.69 mg/dL) and - 0.10 mg/dL (95% CI, - 0.70 to 0.49 mg/dL). There were significant reductions in ALP and PTH levels with standardized mean differences (SMDs) of - 0.65 (95% CI - 1.13 to - 0.16) and - 1.89 (95% CI - 3.44 to - 0.34), respectively. There were significant increases in T-scores with MDs of 0.39 (95% CI 0.10 to 0.69) and 0.79 (95% CI 0.60 to 0.98) for lumbar spine and femoral neck, respectively. Our study demonstrates the estimated incidence of denosumab-associated hypocalcemia in dialysis patients of 42%. From baseline to post-treatment course, although there are no differences in serum calcium and phosphate, our findings suggest significant reductions in ALP and PTH and a significant increase in BMD. Currently, denosumab should not be considered as the treatment of choice in ESRD patients until more safety and efficacy data are available.

Chest Trauma Requiring Admission: Differences in Earthquake Victims and other Modes of Injury

Background The April 25, 2015 Nepal earthquake (7.8 Richter scale) followed by May 12, 2015 major aftershock (7.3 Richter scale) killed more than 9,000 people and injured more than 23,000 people. Dhulikhel Hospital situated at Kavre district of Nepal encountered major bulk of Earthquake victims residing at Sindhuplanchowk, Kavre and Dolakha districts during subsequent earthquake events. Objective To distinguish any significant differences in hospital admitted Earthquake and nonEarthquake chest trauma cases. Method Retrospective study was done comparing earthquake with non-earthquake chest trauma cases admitted in Dhulikhel Hospital. Study included parameters like mode of injury, time taken to reach health center, symptoms at presentation, involvement of chest area, presence and site of rib fracture, presence of hemothorax or pneumothorax, spectrum of treatment required, hospital admission days. Result There were total 23 earthquake victims of which 14 (61%) were female and rest of 9(39%) were male whereas out of total 95 non earthquake cases 23(24%) were female and 72 (76%) were male (p< 0.01). Mean age in earthquake victims was 53.73 (SD 18.33, range 19-84) while non earthquake cases was 46.83(SD 16.53, range 11-90), (p >0.05). Major mode of injuries in earthquake victims was hit by objects (82.60%) followed by fall (17.4 %). Incidence of rib fractures was 69.56% in earthquake victims and 85.26 % in non earthquake cases with average of 2-3 ribs in both cases (p>0.05). There was higher rates of pneumothorax in earthquake victims (52.17%) compared to non earthquake cases (30.52%), (p<0.05). There wasn't evidently major differences in incidence of pulmonary contusion, hemothorax and surgical emphysema. The mean duration of hospital admission days in earthquake victims was 7.78 days while non earthquake cases was 5.04 days (p >0.05). The total number of patients requiring chest tube insertion in earthquake victims was 16(69.56%) while that was 29(30.52 %) in non earthquake patients (p <0.01). Conclusion There was preponderance of female gender in earthquake related cases compared to non earthquake cases. Incidence of rib fracture was higher in earthquake victims. In earthquake victims, higher proportion of patient required chest tube drainage compared to non earthquake cases.

Precontoured Clavicular Locking Plate with Broad Lateral End: A Newly Designed Plate for Lateral Third Clavicle Fractures

Introduction: Various treatment modalities are available but no consensus has been reached for optimal treatment of lateral third clavicle fractures. Precontoured locking plates with broad lateral end for multiple screws fixation is a newly designed plate for lateral third clavicle fractures. The objective of our study was to analyse the functional outcomes as well as complications of this technique in a significant number of cases with long follow-up duration.

Materials and Methods: Forty-six patients with distal third clavicle fractures were treated by precontoured clavicular locking plate with broad lateral end. Functional outcomes were assessed on the basis of Constant-Murley Shoulder Outcome Score and University of California, Los Angeles (UCLA) Shoulder Rating Score, active shoulder range of motion, time for fracture union and coraco-clavicular distance.

Results: The mean Constant-Murley score was 92.56±4.47 (range: 79-98) for injured side and 96.22±2.23 (range: 90-100) for normal side with p-Value 0.56. Mean coraco-clavicular distance at final follow-up was 10.52±1.13 mm (range 9.7 to 11.7 mm) in injured side and 10.25±0.98 mm (range 9.6 to 11.2 mm) in normal side. Mean UCLA Shoulder Rating Score was 32.55±2.12 (range: 27-34) for injured side and 33.46±1.88 (range: 31- 35) on normal side with p value 0.58. No major complications that necessitated revision of surgery occurred in our study.

Conclusion: This newly designed plate seemed extremely useful in successful union of lateral third clavicle fractures, with reduced rate of complications like fixation failures, iatrogenic rotator cuff injury, AC joint osteoarthritis and sub-acromial bursitis, with good functional outcomes.

A veil in the oral cavity: report of two cases of oral synechiae

An oral synechia is an adhesion between the maxilla and the mandible; these adhesions can be found at various locations in the oral cavity. The presence of oral synechiae associated with cleft palate represents a rare congenital deformity. Oral synechiae with cleft palate can have serious implications for airway management and feeding in babies, and hence requires early intervention to reduce morbidity. Two cases of congenital oral synechiae accompanied by cleft palate, in which the synechiae veiled the oral cavity restricting a detailed intraoral examination, are reported here.

Titanium Elastic Nailing System (TENS) for Tibia Fractures in Children: Functional Outcomes and Complications

INTRODUCTION

Closed reduction and cast application is still regarded as first line treatment for pediatric tibial fractures. Over the past few decades, management of pediatric tibial fractures has shifted more towards operative intervention because of quicker recovery, shorter rehabilitation period, less immobilization, lack of stiffness of adjoining joints, and less psychological impact to the children. Flexible intramedullary nails not only fulfill the above advantage but also maintain alignment and rotation.

METHODS

This was a retrospective study of pediatric tibial fractures fixed with two titanium elastic nails through proximal ends of bones. Alignment of fracture, any infection, delayed union, non union, limb length discrepancy, motion of knee joint, and fracture union time were measured during follow-up examination.

RESULTS

Forty-five patients were enrolled into the study out of which 28 (62.2%) were male and 17 (37.8%) were female. Average age of patient was 9.48±2.17 years and average time taken to heal the fractures (both clinical and radiological) was 11.17±2.81 weeks. There were 2 (4.4%) of malunion, 4 (8.8%) of delayed union, 3 (6.6%) of limb shortening, 2 (4.4%) of limb lengthening, 6 (13.6%) of nail prominence and skin irritation, 2 (4.4%) of superficial infection at nail entry site and one case of re-fracture.

CONCLUSIONS

Titanium elastic nail fixation is a simple, easy, rapid, reliable and effective method for management of pediatric tibial fractures in patients with operative indications. There may be the chances of complication following the TENS in tibia but these are avoidable as well as manageable with careful precautions.

Close Versus Limited Open Method of Ender's Nail Fixation in Paediatric Femoral Shaft Fractures

INTRODUCTION

There are various surgical options for treating fracture of femoral shaft in children. Here we compare the results of close with limited open method of Ender's nails fixation of femoral shaft fractures in children.

METHODS

We studied 60 children with femoral shaft fractures in age group 5-15 years. Ender's nail fixation was done by close technique in 40 cases and in 20 cases by limited open technique.

RESULTS

The mean operative time was significantly high in limited open group being 64 minutes in comparison to 50 minutes in close group. There was no significant difference between close and limited open groups with respect to time for partial weight bearing and time for full weight bearing. Fracture united sooner in close group as compared to open group. Union was achieved in all patients within a mean of 11 weeks in close group in comparison to 12.4 weeks in open group. According to the Flynn criteria in close group 34 patients had excellent results, 6 had satisfactory and none poor. In limited open group outcome was excellent in 14 patients, satisfactory in 4 patients and 2 had poor result. There was no significant difference in outcome based on Flynn criteria between two groups.

CONCLUSIONS

Though operative time is more and healing is delayed in Ender's nail fixation by limited open technique, there is no statistical difference in final outcome as per Flynn criteria between close and limited open technique of Ender's nail fixation of femoral shaft fractures in children.

Clinicomicrobiological profile of infective endocarditis in a tertiary care center of Nepal

Background Infective endocarditis is a common problem and data regarding its clinical and microbiological pattern from developing countries are sparse. We studied clinical features and the microbiological pathogens in patients with Infective Endocarditis in our Hospital. Objective To study the clinical profile and microbiological pathogens involved in patients with Infective Endocarditis, admitted under Department of Internal Medicine of B.P Koirala Institute of Health Sciences. Materials and methods A total of 54 patients with history of fever and underlying heart disease were studied. It was a hospital based cross sectional descriptive study done in patients with infective endocarditis presented to us from March 2007 to February 2008 in B.P Koirala Institute of Health Sciences. Results Out of 54 patients, 11 (20.4%) had Dukes definite IE. The male: female ratio was 1.2:1. The mean age of the study group was 27.3 years (range=16-55). In IE group, fever was present in 100% cases (n=11) as it was the inclusion criteria of the study, followed by SOB 81.8% (n=9). History of antibiotic therapy prior to the presentation was present in 36.7 % (n=4) patients. Pallor was the most common sign 63.6% (n=7). Splenomegaly was seen in 18.2% (n=2). Anaemia (Hb<10gm %) in 36.4% (n=4) and microscopic haematuria in 72.3% (n=8) cases. Blood culture positivity was seen in 36.4 %. The most common pathogens were Staphylococcus aureus in 27.3% (n=3) and Acinetobacter species in 9.1% (n=1). Conclusion In our study we found that the clinical spectrum of IE was different from the west in that the majority of patients being young in our study. However, RHD still is the commonest underlying heart disease and Staphylococcus aureus being the commonest isolate. Journal of College of Medical Sciences-Nepal, 2012, Vol-8, No-4, 34-41 DOI: http://dx.doi.org/10.3126/jcmsn.v8i4.8698  

Surgical Management of Cervical Spondylotic Myelopathy

Introduction: The surgical procedure by the anterior, posterior and combined antero-posterior approaches had applied for the treatment of cervical spondylotic myelopathy.  Methods: During the treatment process, all patients were pre-operatively as well post-operatively graded according to Japanese Orthopaedics Association. Several surgical methods such as anterior approach, posterior approach, and combined antero-posterior approach have been addressed for CSM patients, with the choice based on the pathogenesis of the myelopathy. The main indications for surgery were evidence of myelopathy on physical examinations, a JOA score below 13 points help with spinal cord compression observed on plain X-ray, CT scan, MRI studies.  Results: The pre-operative JOA scores were 7.60±1.23 in laminoplasty, 8.30±1.03 in diskectomy and corpectomy and 7.10±1.20 in combined antero-posterior approach patients. At the follow-up after three months the JOA scores were laminoplasty 13.30±1.30, diskectomy and corpectomy 13.55±1.15 and combined antero-posterior 13.50±1.08. The JOA recovery rate averaged, 61.08±11.25% in laminoplasty, 60.67±10.60% in diskectomy and corpectomy and 64.67±10.72% in combined anteroposterior approach. The high- signal intensity changed to normal in 18 out of 28 and no any kyphotic change and instability were found in cervical spine at the follow up.  Conclusions: Patients with OPLL (continuous, segmental and mixed type), stenosis of cervical spinal canal, multilevel cervical spondylosis, large and high ossification of IVDP with stenosis were improved with laminoplasty. Patients with PIVD, CSM with kyphosis, post laminectomy , OPLL herniated type, unstable vertebral alignment, stenosis by osteophytes, were improved with anterior approach . Ossified or deformed OPLL, unstable vertebral with stenosis ,OPLL or OYL with cervical meandearing (swan-neck) were improved with Combined anterior and posterior approach. Keywords: cervical spondylotic mylopathy, anterior cervical diskectomy and fusion, corpectomy.

Surgical management of cervical spondylotic myelopathy

INTRODUCTION

The surgical procedure by the anterior, posterior and combined antero-posterior approaches had applied for the treatment of cervical spondylotic myelopathy.

METHODS

During the treatment process, all patients were pre-operatively as well post-operatively graded according to Japanese Orthopaedics Association. Several surgical methods such as anterior approach, posterior approach, and combined antero-posterior approach have been addressed for CSM patients, with the choice based on the pathogenesis of the myelopathy. The main indications for surgery were evidence of myelopathy on physical examinations, a JOA score below 13 points help with spinal cord compression observed on plain X-ray, CT scan, MRI studies.

RESULTS

The pre-operative JOA scores were 7.60±1.23 in laminoplasty, 8.30±1.03 in diskectomy and corpectomy and 7.10±1.20 in combined antero-posterior approach patients. At the follow-up after three months the JOA scores were laminoplasty 13.30±1.30, diskectomy and corpectomy 13.55±1.15 and combined antero-posterior 13.50±1.08. The JOA recovery rate averaged, 61.08±11.25% in laminoplasty, 60.67±10.60% in diskectomy and corpectomy and 64.67±10.72% in combined antero-posterior approach. The high-signal intensity changed to normal in 18 out of 28 and no any kyphotic change and instability were found in cervical spine at the follow up.

CONCLUSIONS

Patients with OPLL (continuous, segmental and mixed type), stenosis of cervical spinal canal, multilevel cervical spondylosis, large and high ossification of IVDP with stenosis were improved with laminoplasty. Patients with PIVD, CSM with kyphosis, post laminectomy, OPLL herniated type, unstable vertebral alignment, stenosis by osteophytes, were improved with anterior approach. Ossified or deformed OPLL, unstable vertebral with stenosis, OPLL or OYL with cervical meandearing (swan-neck) were improved with Combined anterior and posterior approach.

Effect of haemodynamic and metabolic predictors on echocardiographic left ventricular mass in non-diabetic hypertensive patients

BACKGROUND

Left ventricular hypertrophy is a forerunner of coronary heart disease, congestive cardiac failure, stroke and may also lead to sudden death. Estimation of left ventricular mass by echocardiography offers prognostic information better than the evaluation of traditional cardiovascular risk factors.

OBJECTIVE

The aim of this study was to determine the relative contributions of haemodynamic and metabolic factors affecting left ventricular mass in non-diabetic patients with essential hypertension.

MATERIAL AND METHODS

100 non-diabetic hypertensive patients were taken. The association between age, gender, smoking, alcohol, height, weight, heart rate, clinic blood pressure, fasting blood glucose, lipid profile, haemoglobin, body mass index and stroke volume with LV mass was studied. Left ventricular mass was measured by using standard M-mode echocardiography measurement obtained by way of standard recommended by the American Society of Echocardiography.

RESULTS

Left ventricular mass was analyzed as a continuous variable. In males body mass index (r = .35, p < .004) and stroke volume(r = -.26, p<.039) were significantly correlated with LV mass. In females body weight was significantly related to left ventricular mass(r = .36, p < .02). The independent association between significant factors and left ventricular mass was assessed by stepwise multivariate logistic regression. Body mass index and systolic blood pressure came as independent determinants of left ventricular mass in all patients. A maximum of 13% of left ventricular mass variability could be explained by these two factors.

CONCLUSION

In untreated patients with hypertension patient's body mass index and systolic blood pressure are independent predictors of left ventricular mass after adjustment for other haemodynamic and metabolic factors. They explain a maximum of 13% of left ventricular mass variability. More knowledge is needed about factors that may alter cardiac morphology in the evolution of hypertensive patients.

Prevalence of the metabolic syndrome in acute myocardial infarction and its impact on hospital outcomes

AIMS

To ascertain the prevalence of the metabolic syndrome in patients with acute myocardial infarction; to study the impact of the metabolic syndrome on hospital outcomes; and to find out the association of each component of the metabolic syndrome with acute myocardial infarction (AMI).

SETTING

Coronary care unit, Department of Medicine, B P Koirala Institute of Health Sciences, Dharan, Nepal.

DESIGN

Hospital-based cross-sectional study.

MATERIALS AND METHODS

A total of 84 unselected consecutive patients hospitalized with AMI (diagnosed on the basis of WHO criteria) were categorized according to NCEP ATP III criteria.

STATISTICAL ANALYSIS

Data was analyzed by using the Student's t test and Chi-square test.

RESULTS

Among the 84 AMI patients, 22 (26.19%) fulfilled the criteria for metabolic syndrome. Patients with the metabolic syndrome were older (86% were >50 years of age) and females (27%) were more affected than males (25%). In-hospital case fatality was higher in patients having the metabolic syndrome (5/22) than in those without the syndrome (3/62). Among the five components of the metabolic syndrome, the triglyceride levels had the highest positive predictive value (62%) in AMI; this was followed by fasting blood glucose levels (55%).

CONCLUSION

The prevalence of the metabolic syndrome is 26.19%; it is associated with high mortality; among its components, the triglyceride level has the highest positive predictive value in AMI patients.

Echocardiographic Evaluation of Diastolic Function in Asymptomatic Type 2 Diabetes

INTRODUCTION:Diabetes mellitus is an established risk factor for congestive cardiac failure in which the diastolic function is impaired earlier than the systolic function and majority of these patients maybe asymptomatic without signs of overt heart failure.METHODS:A cross sectional hospital based study was done which included 100 asymptomatic patients with type 2 diabetes without evidence of coronary artery disease, congestive heart failure, thyroid or overt renal disease. LVDD was evaluated by Doppler echocardiography, which included the valsalva maneuver to unmask the pseudonormal pattern of left ventricular filling. The prevalence of LVDD and the associated risk factors were assessed.RESULTS:LVDD was found in 71 subjects (71%), of whom 60 had impaired relaxation and 11 had a pseudonormal pattern of ventricular filling. Systolic function was normal in all subjects, and there was no correlation between LVDD and indexes of metabolic control. It was also found that age > or =45 years was associated with an almost three times higher risk for the development of diastolic dysfunction in type 2 diabetes. Females were at a two times higher risk of developing diastolic dysfunction than when compared to men. Duration of diabetes > or = two years was associated with a two times higher risk for developing diastolic dysfunction.CONCLUSIONS:LVDD is much more common than previously reported in subjects with well-controlled type 2 diabetes who are free of clinically detectable heart disease. The high prevalence of this phenomenon in this high-risk population suggests that screening for LVDD in type 2 diabetes should include procedures such as the valsalva maneuver to unmask a pseudonormal pattern of ventricular filling.Keywords:diabetes mellitus, diastolic dysfunction, echocardiography, impaired relaxation, pseudonormal

Delayed presentation of acute coronary syndrome: a challenge in its early management

INTRODUCTION

The time of presentation of acute coronary syndrome from the onset of chest pain determines the treatment modality and prognosis. Delayed presentation is associated with a poor outcome. In the present study, we tried to find out the causes of late presentation of ACS in a tertiary care center in the eastern part of Nepal.

METHODS

It was a cross-sectional descriptive study that included 100 consecutive patients with ACS presenting to our institute over a period of 8 months. They were studied for their demographic profile, delay in presentation, the management done at the local centers and their final diagnosis.

RESULTS

We found that patients living within Dharan City reached BPKIHS within 20 hours of the onset of chest pain while those from outside the city who came directly reached within 63 hours. Other patients reached their respective local centers (health posts, district hospitals and private clinics) within 39 hours. The commonest cause of delay was vehicular problem followed by unnecessary delay at the local centers. The work up for chest pain was inadequate in these centers. Late presentation to our institute significantly affected the optimal management.

CONCLUSIONS

We found that significant number of patients with ACS from eastern Nepal presented late in our tertiary care center. In order to improve ACS outcome in this region, we advise equipping the local centers with electrocardiogram machines, improvement in ambulance services and a greater emphasis on coronary artery disease awareness programs as well as initiating preventive measures.

Echocardiographic evaluation of diastolic function in asymptomatic type 2 diabetes

INTRODUCTION

Diabetes mellitus is an established risk factor for congestive cardiac failure in which the diastolic function is impaired earlier than the systolic function and majority of these patients maybe asymptomatic without signs of overt heart failure.

METHODS

A cross sectional hospital based study was done which included 100 asymptomatic patients with type 2 diabetes without evidence of coronary artery disease, congestive heart failure, thyroid or overt renal disease. LVDD was evaluated by Doppler echocardiography, which included the valsalva maneuver to unmask the pseudonormal pattern of left ventricular filling. The prevalence of LVDD and the associated risk factors were assessed.

RESULTS

LVDD was found in 71 subjects (71%), of whom 60 had impaired relaxation and 11 had a pseudonormal pattern of ventricular filling. Systolic function was normal in all subjects, and there was no correlation between LVDD and indexes of metabolic control. It was also found that age > or =45 years was associated with an almost three times higher risk for the development of diastolic dysfunction in type 2 diabetes. Females were at a two times higher risk of developing diastolic dysfunction than when compared to men. Duration of diabetes > or = two years was associated with a two times higher risk for developing diastolic dysfunction.

CONCLUSIONS

LVDD is much more common than previously reported in subjects with well-controlled type 2 diabetes who are free of clinically detectable heart disease. The high prevalence of this phenomenon in this high-risk population suggests that screening for LVDD in type 2 diabetes should include procedures such as the valsalva maneuver to unmask a pseudonormal pattern of ventricular filling.

Association of cardiovascular events with glycosylated haemoglobin in diabetic patients

BACKGROUND

In persons with diabetes, chronic hyperglycemia (assessed by glycosylated hemoglobin level) is related to the development of microvascular disease; however, the relation of glycosylated hemoglobin (HbA1c) to macrovascular disease is less clear.

OBJECTIVE

To study the association of cardiovascular events (CVE) with glycosylated haemoglobin in diabetic patients.

DESIGN

Case control study.

SETTING

B. P. Koirala Institute of Health Sciences (BPKIHS), Dharan, Nepal.

MATERIALS AND METHOD

Fifty diabetic patients with recent cardiovascular events: myocardial infarction (MI) or stroke was included in the study. There were 25 patients of myocardial infarction and 25 patients of stroke. Fifty diabetic patients without cardiovascular events were taken as control.

RESULTS

After adjustment for age, smoking, body mass index, systolic blood pressure and total cholesterol at baseline, level of HbA1c was statistically significant (p = 0.017) among patients with CVE. For MI, level of HbA1c was statistically significant (p = 0.018) while for stroke, level of HbA1c was not significant (p = 0.694). Mean blood glucose also predicted CVE and MI but not stroke in this study (p values = 0.006, 0.006 and 0.670 respectively). Fasting and postprandial plasma glucose was statistically significant in CVE (p values = 0.024 and 0.019 respectively). Urine protein was statistically significant for CVE, MI and stroke (p values = 0.000, 0.032, 0.032 and OR 4.571 (95% CI: 1.963-10.646), 2.667 (95% CI: 1.043-6.815), 2.667 (95% CI: 1.043-6.815) respectively.

LIMITATIONS

Sample size was limited due to time constraint and limited resources. Cases with peripheral artery disease were not included in the study.

CONCLUSION

Glycosylated haemoglobin is associated with cardiovascular events and myocardial infarction but not stroke.

Effect of preload reduction by haemodialysis on doppler indices of diastolic function in patients with end-stage renal disease

OBJECTIVE

To assess the influence of preload reduction by haemodialysis on Doppler echocardiographic indices of cardiac diastolic function.

METHODOLOGY

Parameters of left ventricular diastolic function were measured in patients with end-stage renal disease before and after a single session of haemodialysis. Patients with valvular heart disease, coronary artery disease, cardiomyopathies, pericardial disease and those not in sinus rhythm were excluded from the study.

RESULTS

Seventeen subjects (12 males and 5 females, mean age 48 +/- 16 years) were studied. Over the duration of 3.7 +/- 0.6 hours of haemodialysis, 2.6 +/- 1.3 litres of ultrafiltrate was removed. The comparison of pre and post haemodialysis peak mitral E and A velocities showed a decrease in E velocity (p < 0.01) whereas the change in A velocity was not significant. The E/A ratio decreased significantly (p < 0.05).The decrease in E velocity correlated well with the amount of ultrafiltrate (r = 0.653, p < 0.01). There was a significant increase in isovolumetric relaxation time (p< 0.05) whereas deceleration time did not change (p =0.3).

CONCLUSION

Ultrafiltration during haemodialysis causes a rapid reduction in preload. It results in decreased early left ventricular diastolic filling without a change in the atrial phase of filling, hence causing a decrease in calculated E/A ratio.

Hemidiaphragmatic paralysis: a rare complication of cervical herpes zoster

Herpes zoster, a sequel of the reactivation of the varicella zoster virus, usually presents with cutaneous eruptions associated with intense pain and burning sensation in the affected dermatomes. Motor weakness, however, can sometimes complicate herpes zoster. In this report we present a case that had diaphragmatic motor weakness as a sequel of herpes zoster lesions in the neck.

The "third eye"-- a new concept of trans-differentiation of pineal gland into median eye in amphibian tadpoles of Bufo melanostictus

Median third eye was found to develop from transplanted pineal gland of external gill stage tadpoles in the recipient 5 toe stage tadpoles of Bufo melanostictus. Pineal gland along with a bit part of brain tissue of the donor external gill stage tadpole was cut out and transplanted into a pit made between two lateral eyes of 5 toe stage recipient tadpoles. Half of the operated tadpoles were treated with vitamin A (15 IU/ml.) for 15 days. Median "third eye" was found to develop in the both untreated and vitamin A treated tadpoles. However, vitamin A increased the percentage of the development of median eyes. Morphological and histological study revealed that newly transformed median eyes were similar to that of normal functional eyes. A stalk like structure developed which connects the median eye to the brain. The median third eye could not develop when pineal gland of 5 toe stage mature tadpole was transplanted into the tadpole of the same age.

Treatment of visceral leishmaniasis in south-eastern Nepal: decreasing efficacy of sodium stibogluconate and need for a policy to limit further decline

Sodium stibogluconate (SSG) is the first-line therapy for visceral leishmaniasis (VL) in south-eastern Nepal. Recent studies from the neighbouring state of Bihar, India, have shown a dramatic fall in cure rates with treatment failure occurring in up to 65% of VL patients treated with SSG. A prospective study was conducted at a tertiary-level hospital located in south-eastern Nepal from July 1999 to January 2001. Parasitologically proven kala-azar patients with no previous history of treatment for VL were treated with SSG 20 mg/kg/d for 30 d which was extended to 40 d in those with persistent positive parasitology. Of the 110 patients who completed SSG therapy and were assessed at 1 and 6 months, definite cure was achieved in 99 patients (90%) and SSG failure occurred in 11 patients (10%). Except for the presence of hepatomegaly and a lower platelet count there was no clinical or laboratory baseline characteristic associated with treatment failure. A significantly lower cure rate (76%, P = 0.03) was observed in patients from the district of Saptari, which borders the antimony-resistant VL areas of Bihar. The efficacy of SSG as a first-line treatment for VL in south-eastern Nepal was still satisfactory, except for the patients living closer to the antimony-resistant VL areas of India. These findings indicate that the spread of resistance to antimonials is already taking place in Nepal and that a policy to control further spread should be urgently implemented.

Measurement of nucleobase pKa values in model mononucleotides shows RNA-RNA duplexes to be more stable than DNA-DNA duplexes

To understand why the RNA-RNA duplexes in general has a higher thermodynamic stability over the corresponding DNA-DNA duplexes, we have measured the pK(a) values of both nucleoside 3',5'-bis-ethyl phosphates [Etp(d/rN)pEt] and nucleoside 3'-ethyl phosphates [(d/rN)pEt] (N = A, G, C, or T/U), modeling as donors and acceptors of base pairs in duplexes. While the 3',5'-bis-phosphates, Etp(d/rN)pEt, mimic the internucleotidic monomeric units of DNA and RNA, in which the stacking contribution is completely absent, the 3'-ethyl phosphates, (d/rN)pEt, mimic the nucleotide at the 5'-end. The pK(a) values of the nucleobase in each of these model nucleoside phosphates have been determined with low pK(a) error (sigma = +/-0.01 to 0.02) by (1)H NMR (at 500 MHz) with 20-33 different pH measurements for each compound. This study has led us to show the following: (1) All monomeric DNA nucleobases are more basic than the corresponding RNA nucleobases in their respective Etp(d/rN)pEt and (d/rN)pEt. (2) The pK(a) values of the monomeric nucleotide blocks as well as Delta pK(a) values between the donor and acceptor can be used to understand the relative base-pairing strength in the oligomeric duplexes in the RNA and DNA series. (3) The Delta G*(pKa) of the donor and acceptor of the base pair in duplexes enables a qualitative dissection of the relative strength of the base-pairing and stacking in the RNA-RNA over the DNA-DNA duplexes. (4) It is also found that the relative contribution of base-pairing strength and nucleobase stacking in RNA-RNA over DNA-DNA is mutually compensating as the % A-T/U content increases or decreases. This interdependency of stacking and hydrogen bonding can be potentially important in the molecular design of the base-pair mimics to expand the alphabet of the genetic code.

Cross-modulation of the pKa of nucleobases in a single-stranded hexameric-RNA due to tandem electrostatic nearest-neighbor interactions

The pH titration studies (pH 6.7-12.1) in a series of dimeric, trimeric, tetrameric, pentameric, and hexameric oligo-RNA molecules [GpA (2a), GpC (3a), GpApC (5), GpA(1)pA(2)pC (6), GpA(1)pA(2)pA(3)pC (7), GpA(1)pA(2)pA(3)pA(4)pC (8)] have shown that the pK(a) of N(1)-H of 9-guaninyl could be measured not only from its own deltaH8G, but also from the aromatic marker protons of other constituent nucleobases. The relative chemical shift differences [Deltadelta((N)(-)(D))] between the protons in various nucleotide residues in the oligo-RNAs at the neutral (N) and deprotonated (D) states of the guanine moiety show that the generation of the 5'-(9-guanylate ion) in oligo-RNAs 2-8 reduces the stability of the stacked helical RNA conformation owing to the destabilizing anion(G(-))-pi/dipole(Im(delta)(-)) interaction. This destabilizing effect in the deprotonated RNA is, however, opposed by the electrostatically attractive atom-pisigma (major) as well as the anion(G(-))-pi/dipole(Py(delta)(+)) (minor) interactions. Our studies have demonstrated that the electrostatically repulsive anion(G(-))-pi/dipole(Im(delta)(-)) interaction propagates from the first to the third nucleobase quite strongly in the oligo-RNAs 6-8, causing destacking of the helix, and then its effect is gradually reduced, although it is clearly NMR detectable along the RNA chain. Thus, such specific generation of a charge at a single nucleobase moiety allows us to explore the relative strength of stacking within a single-stranded helix. The pK(a) of 5'-Gp residue from its own deltaH8G in the hexameric RNA 8 is found to be 9.76 +/- 0.01; it, however, varies from 9.65 +/- 0.01 to 10.5 +/- 0.07 along the RNA chain as measured from the other marker protons (H2, H8, H5, and H6) of 9-adeninyl and 1-cytosinyl residues. This nucleobase-dependent modulation of pK(a)s (DeltapK(a) +/- 0.9) of 9-guaninyl obtained from other nucleobases in the hexameric RNA 8 represents a difference of ca. 5.1 kJ mol(-)(1), which has been attributed to the variable strength of electrostatic interactions between the electron densities of the involved atoms in the offset stacked nucleobases as well as with that of the phosphates. The chemical implication of this variable pK(a) for guanin-9-yl deprotonation as obtained from all other marker protons of each nucleotide residue within a ssRNA molecule is that it enables us to experimentally understand the variation of the electronic microenvironment around each constituent nucleobase along the RNA chain in a stepwise manner with very high accuracy without having to make any assumption. This means that the pseudoaromaticity of neighboring 9-adeninyl and next-neighbor nucleobases within a polyanionic sugar-phosphate backbone of a ssRNA can vary from one case to another due to cross-modulation of an electronically coupled pi system by a neighboring nucleobase. This modulation may depend on the sequence context, spatial proximity of the negatively charged phosphates, as well as whether the offset stacking is ON or OFF. The net outcome of this electrostatic interaction between the neighbors is creation of new sequence-dependent hybrid nucleobases in an oligo- or polynucleotide whose properties are unlike the monomeric counterpart, which may have considerable biological implications.

Prospective evaluation and comparison of the direct agglutination test and an rK39-antigen-based dipstick test for the diagnosis of suspected kala-azar in Nepal

The diagnosis of visceral leishmaniasis (kala-azar) remains difficult in rural endemic areas and practical and reliable tests are badly needed. Two serological tests, the Direct Agglutination Test (DAT) and an rK39-antigen-based dipstick test, were compared to parasitological diagnosis in a group of 184 patients presenting at a tertiary care centre in south-eastern Nepal with a history of fever > or = 14 days and splenomegaly; 139 patients had a parasitologically proven kala-azar and 45 patients had a negative parasitological work-up. The rK39 dipstick showed a sensitivity of 97% and a specificity of 71%. The DAT was up to 99% sensitive with a low cut-off titre (1:400) but its specificity did not exceed 82% even with a high cut-off titre (1:51 200). Both tests could be used for screening suspect patients in endemic areas. However, their use as confirmatory tests should be restricted to situations where the proportion of kala-azar among clinical suspect patients is high. The rK39 dipstick is cheaper and easier to use than the DAT and could be used widely provided that both its performance and production remain stable.

Tandem electrostatic effect from the first to the third aglycon in the trimeric RNA owing to the nearest-neighbor interaction

We here show an electrostatic polar-pi interaction from the first to the third aglycon, via the second aglycon, in the ground state in two single stranded trimeric RNAs, 5'-GpA(1)pA(2)-3' (3) and 5'-GpApC-3' (4), as a result of intramolecular nearest neighbor offset-stacking. The experimental evidence in support of this conclusion has been obtained by comparing the pK(a)s of each aglycone in the two trimers with those of guanosine 3'-ethyl phosphate, GpEt (1) and 5'-GpA-3' (2): Thus, the pK(a) of N(1)-H of guanin-9-yl of 5'-GpA(1)pA(2)-3' (3) could be measured by pH titration (pH 7.3-11.6) of its own deltaH8G (pK(a) 9.75 +/- 0.02) as well as from deltaH8A(1) (pK(a) 9.72 +/- 0.02) and deltaH2A(1) (pK(a) 9.83 +/- 0.04) of the neighboring pA(1)p moiety and the deltaH8A(2) (pK(a) 9.83 +/- 0.02) of the terminal pA(2) moiety. Similarly, the pH titration of GpApC (4) shows the pK(a) of N(1)-H of guanin-9-yl from its own deltaH8G (pK(a) 9.88 +/- 0.03) as well as from deltaH8A (pK(a) 9.87 +/- 0.01) of the neighboring pAp moiety, and deltaH5/H6C (pK(a) 9.88 +/- 0.01 and 9.90 +/- 0.01 respectively) of the 3'-terminal cytosin-1-yl. This intramolecular nearest neighbor electrostatic interaction in the single-stranded RNA modulates the pseudoaromaticity of the nearest neighbors by almost total transmission of because they constitute an extended array of offset-stacked coupled aromatic heterocycles within a polyanionic sugar-phosphate backbone at the ground state. The enhanced basicity of Gp residue by ca. 0.6 pK(a) unit in the trimers compared to that of the dimer is a result of the change in the electrostatic microenvironment owing to the nearest neighbors in the former (the nucleobases as well as the phosphates). Thus, the from the 5'-guanylate ion to the 3'-end aglycon via the central adenin-9-yl is 55 to 56 kJ mol(-)(1) in each step through a distance spanning approximately 6.8 A in an unfolded state. As a result, the pK(a) of guanin-9-yl moiety has become 9.25 +/- 0.02 in GpEt (1), 9.17 +/- 0.02 in GpA (2), 9.75 +/- 0.02 in GpApA (3), and 9.88 +/- 0.03 in GpApC (4). This means that guanin-9-yl moiety of trimers 3 and 4 is more basic than in the monomer or the dimer. The net outcome of this electrostatic cross-talk between the two neighboring heterocycles is creation of new hybrid aglycones in an oligo or polynucleotide, whose physicochemical property and the pseudoaromatic character are completely dependent both upon the nearest neighbors, and whether they are stacked or unstacked. Thus, this tunable physicochemical property of an aglycon (an array of the extended genetic code) may have considerable implication in our understanding of the specific ligand binding ability of an aptamer, the pK(a) and the hydrogen bonding ability of nucleic acids in a microenvironment, or in the triplet usage by the anticodon-codon interaction in the protein biosynthesis in the ribosome.

A repertoire of pyridinium-phenyl-methyl cross-talk through a cascade of intramolecular electrostatic interactions

Direct intramolecular cation-pi interaction between phenyl and pyridinium moieties in 1a(+) has been experimentally evidenced through pH-dependent (1)H NMR titration. The basicity of the pyridinyl group (pK(a) 2.9) in 1a can be measured both from the pH-dependent chemical shifts of the pyridinyl protons as well as from the protons of the neighboring phenyl and methyl groups as a result of electrostatic interaction between the phenyl and the pyridinium ion in 1a(+) at the ground state. The net result of this nearest neighbor electrostatic interaction is that the pyridinium moiety in 1a becomes more basic (pK(a) 2.92) compared to that in the standard 2a (pK(a) 2.56) as a consequence of edge-to-face cation (pyridinium)-pi (phenyl) interaction, giving a free energy of stabilization (DeltaDeltaG(o)pKa) of -2.1 kJ mol(-1). The fact that the pH-dependent downfield shifts of the phenyl and methyl protons give the pK(a) of the pyridine moiety of 1a also suggests that the nearest neighbor cation (pyridinium)-pi (phenyl) interaction also steers the CH (methyl)-pi (phenyl) interaction in tandem. This means that the whole pyridine-phenyl-methyl system in 1a(+) is electronically coupled at the ground state, cross-modulating the physicochemical property of the next neighbor by using the electrostatics as the engine, and the origin of this electrostatics is a far away point in the molecule-the pyridinyl-nitrogen. The relative chemical shift changes and the pK(a) differences show that the cation (pyridinium)-pi (phenyl) interaction is indeed more stable (DeltaDeltaG(o)pKa = -2.1 kJ mol(-1)) than that of the CH (methyl)-pi (phenyl) interaction (DeltaDeltaG(o)pKa = -0.8 kJ mol(-1)). Since the pK(a) of the pyridine moiety in 1a is also obtained through the pH-dependent shifts of both phenyl and methyl protons, it suggests that the net electrostatic mediated charge transfer from the phenyl to the pyridinium and its effect on the CH (methyl)-pi (phenyl) interaction corresponds to DeltaG(o)pKa of the pyridinium ion (approximately 17.5 kJ mol(-1)), which means that the aromatic characters of the phenyl and the pyridinium rings in 1a(+) have been cross-modulated owing to the edge-to-face interaction proportional to this DeltaG(o)pKa change.