Semisynthetic polymyxins with potent antibacterial activity and reduced kidney cell toxicity

The growing incidence of infections caused by multi-drug resistant Gram-negative bacteria has led to an increased use of last-resort antibiotics such as the polymyxins. Polymyxin therapy is limited by toxicity concerns, most notably nephrotoxicity. Recently we reported the development of a novel class of semisynthetic polymyxins with reduced toxicity wherein the N-terminal lipid and diaminobutyric acid residue are replaced by a cysteine-linked lipid featuring a reductively labile disulfide bond. In the present study we further explored the potential of this approach by also varying the amino acid residue directly adjacent to the polymyxin macrocycle. This led to the identification of new semisynthetic polymyxins that maintain the potent antibacterial activity of the clinically used polymyxin B while exhibiting a further reduction in toxicity toward human proximal tubule epithelial cells. Furthermore, these new polymyxins were found to effectively synergize with novobiocin, rifampicin, and erythromycin against mcr-positive, polymyxin resistant E. coli.

BQ788 reveals glial ETB receptor modulation of neuronal cholinergic and nitrergic pathways to inhibit intestinal motility: Linked to postoperative ileus

BACKGROUND AND PURPOSE

ET-1 signalling modulates intestinal motility and inflammation, but the role of ET-1/ETB receptor signalling is poorly understood. Enteric glia modulate normal motility and inflammation. We investigated whether glial ETB signalling regulates neural-motor pathways of intestinal motility and inflammation.

EXPERIMENTAL APPROACH

We studied ETB signalling using: ETB drugs (ET-1, SaTX, BQ788), activity-dependent stimulation of neurons (high K+ -depolarization, EFS), gliotoxins, Tg (Ednrb-EGFP)EP59Gsat/Mmucd mice, cell-specific mRNA in Sox10CreERT2 ;Rpl22-HAflx or ChATCre ;Rpl22-HAflx mice, Sox10CreERT2 ::GCaMP5g-tdT, Wnt1Cre2 ::GCaMP5g-tdT mice, muscle tension recordings, fluid-induced peristalsis, ET-1 expression, qPCR, western blots, 3-D LSM-immunofluorescence co-labelling studies in LMMP-CM and a postoperative ileus (POI) model of intestinal inflammation.

KEY RESULTS

In the muscularis externa ETB receptor is expressed exclusively in glia. ET-1 is expressed in RiboTag (ChAT)-neurons, isolated ganglia and intra-ganglionic varicose-nerve fibres co-labelled with peripherin or SP. ET-1 release provides activity-dependent glial ETB receptor modulation of Ca2+ waves in neural evoked glial responses. BQ788 reveals amplification of glial and neuronal Ca2+ responses and excitatory cholinergic contractions, sensitive to L-NAME. Gliotoxins disrupt SaTX-induced glial-Ca2+ waves and prevent BQ788 amplification of contractions. The ETB receptor is linked to inhibition of contractions and peristalsis. Inflammation causes glial ETB up-regulation, SaTX-hypersensitivity and glial amplification of ETB signalling. In vivo BQ788 (i.p., 1 mg·kg-1 ) attenuates intestinal inflammation in POI.

CONCLUSION AND IMPLICATIONS

Enteric glial ET-1/ETB signalling provides dual modulation of neural-motor circuits to inhibit motility. It inhibits excitatory cholinergic and stimulates inhibitory nitrergic motor pathways. Amplification of glial ETB receptors is linked to muscularis externa inflammation and possibly pathogenic mechanisms of POI.

Can a shock-induced phonon up-pumping model relate to impact sensitivity of molecular crystals, polymorphs and cocrystals?

Impact sensitivity engineering of high-energy molecular crystals requires accurate predictive models. For this purpose, the promising multi-phonon based approach is selected, assessing a bit more its strengths and weaknesses. Presently used with high-quality phonon calculations of 22 molecular crystals, using a physics-based criterion to determine the phonon bath extent, the resulting intrinsic shock sensitivity index (SSI) is compared to the most common marker of impact sensitivity, h 50, as determined from drop-weight impact tests. Selecting a data subset from experiments performed under very similar conditions (2.5 kg hammer with grit and 30-40 mg samples), the model can predict h 50 values for mono-molecular crystals with very good accuracy, including the ability to discriminate the polymorphs of HMX and CL20. This very good agreement validates an initial indirect up-pumping mechanism occurring under these conditions, where the doorway modes also interact with the phonon bath. However, the phonon bath criterion for mono-molecular crystals does not transfer well to cocrystals. Owing to the vibrational coupling of the co-molecules, it seems a broader phonon bath should be considered. Additionally recalling experimental uncertainty and various experimental factors affecting h 50 values for a given compounds, we recommend that the density of the sample, granularity and morphology be systematically considered and reported along with measurements, which will in turn allow for more systematic data and predictive capabilities for sensitivity models.

Unpacking Land Degradation Neutrality (LDN), An Emerging Paradigm to Conserve Land Systems’ Sustainability in the 21st Century? Meta-analysis of Challenges and Opportunities

The UN Sustainable Development Goals specifically note the growing importance of land degradation management and mitigation strategies, advocating for global collaboration and innovative research and policy outlook. In this reflective summary, we synthesize the current worldview (post-2000) on land degradation neutrality (LDN), an emerging concept in the field of environmental sustainability that advocates a dynamic balance between degradation and restoration, to ensure no net loss in productive land resources. We first introduce the LDN Causal Framework (theoretical framework of LDN), followed by the Logic Model – guideline for on-ground LDN method implementation (comprising preparatory activities, followed by Integrated Land Use Planning (ILUP), and LDN Response Hierarchy (Avoid-Reduce-Reverse)). We draw attention to growing concerns about LDN technical problems: restore vs. rehabilitate; selecting indicator variables, and establishing a baseline. In the final section, we reflect on the social-ecological aspect of LDN – harnessing participatory action (multi-stakeholder engagement) and gender mainstreaming. Overall, LDN presents an umbrella vision for environmental regeneration and land capital management, that requires seamless integration of natural with social sciences, the policy with law, and requires strategic community mobilization.

Improved predictions of thermomechanical properties of molecular crystals from energy and dispersion corrected DFT

Thermal stability and pressure-dependent changes are key to molecular crystals and their properties. The determination of their thermal properties from ab initio methods is, however, a challenging task. While the low-frequency phonon spectrum related to intermolecular vibrations remains difficult to describe, the Quasi-Harmonic Approximation (QHA) also induces for molecular crystals a significant volume deviation, which makes their thermal behavior ill-determined. To overcome these difficulties, we consider a pragmatic energy correction (EC) that has long been used for atomic crystals, and we presently report the first ever use for molecular crystals. Applying the QHA in dispersion-corrected density functional theory (DFT-D) calculations with an ab initio parameterized EC, the resulting model can simultaneously and accurately derive thermal and mechanical properties of high-explosive molecular crystals. When compared to experiments, the mean absolute percent error of previous DFT-based thermomechanical models is 12% for mechanical and 31% for thermal properties. Our model performs significantly better and reduces these uncertainties to 4.1% and 9.8%, respectively. In particular, the agreement between our model and experiments for the thermal properties is three times better. This significant improvement greatly benefits the determination of thermomechanical properties such as the Grüneisen parameter and the shock properties. The method has been successfully applied to molecular crystals showing a large diversity of weak intermolecular interactions (β-1,3,5,7-tetranitro-1,3,5,7-tetrazoctane (HMX), α-1,1-diamino-2,2-dinitroethylene (FOX-7), Triaminotrinitrobenzene (TATB), ε-Hexanitrohexaazaisowurtzitane (CL20), and Pentaerythritol tetranitrate (PETN)-I). Due to its accuracy and transferability, our model is expected to work for a large class of computationally designed molecular crystals and co-crystals, providing a basis for a predictive framework.

Half metallicity in Cr substituted Fe2TiSn

Band structure tailoring has been a great avenue to achieve the half-metallic electronic ground state in materials. Applying this approach to the full Heusler alloy Fe₂TiSn, Cr is introduced systematically at Ti site that conforms to the chemical formula \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Fe}}_{2} {\text{Ti}}_{{1 - x}} {\text{Cr}}_{x}$$\end{document}Fe2Ti1-xCrxSn. Compositions so obtained have been investigated for its electronic, magnetic, and electrical transport properties with an aim to observe the half-metallic ferromagnetic ground state, anticipated theoretically for Fe₂CrSn. Our experimental study using synchrotron X-ray diffraction reveals that only compositions with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$x \le$$\end{document}x≤ 0.25 yield phase pure L2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_1$$\end{document}1 cubic structures. The non-magnetic ground state of Fe₂TiSn gets dramatically affected upon inclusion of Cr giving rise to a localized magnetic moment in the background of Ruderman–Kittel–Kasuya–Yosida (RKKY) correlations. The ferromagnetic interactions begin to dominate for x = 0.25 composition. Results of its resistivity and magnetoresistance (MR) measurement point towards a half-metallic ground state. The calculation of exchange coupling parameter, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {J}_{{ij}}$$\end{document}Jij, and orbital projected density of states that indicate a change in hybridization between 3d and 5p orbital, support the observations made from the study of local crystal structure made using the extended X-ray absorption fine structure spectroscopy. Our findings here highlight an interesting prospect of finding half-metallicity via band structure tailoring for wide application in spintronics devices.

T11TS immunotherapy potentiates the repressed calcineurin-NFAT signalling pathway of T cells in Cryptococcus neoformans infected rats: a cue towards T-cell activation for antifungal immunity

AIMS

To examine the modulation of the interacting partners of the calcineurin (CaN)-NFAT pathway in T cells during Cryptococcus neoformans fungal infection and post-T11TS immunotherapy.

METHODS AND RESULTS

Wistar rats were infected with C. neoformans and followed by immunotherapy with immune-potentiator T11TS. T cells were analysed by flow cytometry, immunoblotting and nuclear translocation study. The signalling proteins LCK, FYN, LAT, PLCγ1 and CaN in T cells were regulated by C. neoformans infection resulting in reduced nuclear translocation of NFAT and IL-2 expression. Following T11TS immunotherapy, the expressions of the above-mentioned proteins were boosted and thus resulting in the clearance of C. neoformans from lung and spleen.

CONCLUSIONS

The precise mechanism of suppression of the T-cell function by C. neoformans is still unknown. Previously, we have shown that T11TS positively regulates the function of T cells to abrogate glioma and other immunosuppressive conditions. T11TS immunotherapy increased the expression of the above signalling partners of the CaN-NFAT pathway in T cells and improved nuclear retention of NFAT. As a result, an increased IL-2 expression leads to activation and proliferation of T cells.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results demonstrate the role of T11TS in restoring the CaN-NFAT signalling pathway in T cells. It identifies T11TS as an immunotherapeutic agent with potential clinical outcomes to counteract C. neoformans infection.

Demonstration of Athena X-IFU Compatible 40-Row Time-Division-Multiplexed Readout

Time-division multiplexing (TDM) is the backup readout technology for the X-ray Integral Field Unit (X-IFU), a 3,168-pixel X-ray transition-edge sensor (TES) array that will provide imaging spectroscopy for ESA's Athena satellite mission. X-0IFU design studies are considering readout with a multiplexing factor of up to 40. We present data showing 40-row TDM readout (32 TES rows + 8 repeats of the last row) of TESs that are of the same type as those being planned for X-IFU, using measurement and analysis parameters within the ranges specified for X-IFU. Singlecolumn TDM measurements have best-fit energy resolution of (1.91 ± 0.01) eV for the Al Kα complex (1.5 keV), (2.10 ± 0.02) eV for Ti Kα (4.5 keV), (2.23 ± 0.02) eV for Mn Kα (5.9 keV), (2.40 ± 0.02) eV for Co Kα (6.9 keV), and (3.44 ± 0.04) eV for Br Kα (11.9 keV). Three-column measurements have best-fit resolution of (2.03 ± 0.01) eV for Ti Kα and (2.40 ± 0.01) eV for Co Kα. The degradation due to the multiplexed readout ranges from 0.1 eV at the lower end of the energy range to 0.5 eV at the higher end. The demonstrated performance meets X-IFU's energy-resolution and energy-range requirements. True 40-row TDM readout, without repeated rows, of kilopixel scale arrays of X-IFU-like TESs is now under development.

Optimization of Time- and Code-Division-Multiplexed Readout for Athena X-IFU

Readout of a large, spacecraft-based array of superconducting transition-edge sensors (TESs) requires careful management of the layout area and power dissipation of the cryogenic-circuit components. We present three optimizations of our time- (TDM) and code-division-multiplexing (CDM) systems for the X-ray Integral Field Unit (X-IFU), a several-thousand-pixel-TES array for the planned Athena-satellite mission. The first optimization is a new readout scheme that is a hybrid of CDM and TDM. This C/TDM architecture balances CDM's noise advantage with TDM's layout compactness. The second is a redesign of a component: the shunt resistor that provides a dc-voltage bias to the TESs. A new layout and a thicker Pd-Au resistive layer combine to reduce this resistor's area by more than a factor of 5. Third, we have studied the power dissipated by the first-stage SQUIDs (superconducting quantum-interference devices) and the readout noise versus the critical current of the first-stage SqUIDs. As a result, the X-IFU TDM and C/TDM SQUIDs will have a specified junction critical current of 5 μA. Based on these design optimizations and TDM experiments described by Durkin, et al. (these proceedings), TDM meets all requirements to be X-IFU's backup-readout option. Hybrid C/TDM is another viable option that could save spacecraft resources.

Unraveling the physical properties and superparamagnetism in anti-site disorder controlled Fe2TiSn

With an aim to control the anti-site disorder between Fe and Ti atoms in the full Heusler alloy, Fe[Formula: see text]TiSn, we substitute a small percentage of Ti at Fe site to form the Fe[Formula: see text]Ti[Formula: see text]Sn ([Formula: see text]) series. Using the incident x-rays tuned to the Fe K-edge absorption energy, we record the high resolution synchrotron x-ray diffraction profiles and unambiguously show the reduction in anti-site disorder. In particular, the Fe-Ti anti-site disorder decreases up to an excess Ti content of 0.07; further increase of Ti content leads to disorder between Ti-Sn sites. Detailed characterization vis-á-vis the excess Ti content has been carried out in terms of its thermal and electrical transport, and magnetic properties. Signatures of strong spin fluctuation are seen in all the physical properties reported here. The much disputed high value of the Sommerfeld constant has been shown to be a resultant of such strong spin fluctuations, thus ruling out the long standing controversy of heavy fermionic nature of Fe[Formula: see text]TiSn. Magnetization and the Seebeck coefficient show clear dependence on the disorder. Both dc and ac magnetic measurements reveal the low temperature superparamagnetic nature of this system, comprising of large magnetic clusters [Formula: see text]3 nm in size.

A flexible-molecule force field to model and study hexanitrohexaazaisowurtzitane (CL-20) – polymorphism under extreme conditions

The quantum-chemistry based force field (FF) developed for HMX by Smith and Bharadwaj (SB) [G. D. Smith and R. K. Bharadwaj, J. Phys. Chem. B, 1999, 103(18), 3570–3575] is transferred to another nitramine of different stoichiometry: hexanitrohexaazaisowurtzitane (CL-20 or HNIW). The modification of a single parameter alongside a very small number of add-ons related to carbon–carbon bonds, angles and dihedrals lead to two SB FF variants denoted SB-CL20 and SB-CL20 + CCNN. These flexible-molecule FFs should inherit the predictive capabilities of SB FF. For this purpose, we perform Molecular Dynamics simulations at ambient temperature and selected pressures. The modeled structures of the various CL-20 polymorphs are consistent with experimental data. Focusing on the ε-polymorph, we determine an equation of state which consolidates the general trend underpinned by most published results, and we confirm the increasing stiffness of the crystal under pressures up to 90 GPa. Moreover, we link some subtle pressure-induced changes of the elastic and structural properties to the flexibility and mobility of well-identified nitro groups. Finally, the simulations of the γ ↔ ζ phase transition suggest different multiple-step direct and reverse thermodynamic paths.

The quantum-chemistry based force field developed by Smith and Bharadwaj is transferred to hexanitrohexaazaisowurtzitane (CL20), revealing pressure-induced alterations of ε-CL20.

Nonsmoked Tobacco Addiction Playing a Major Role in Oral Mucosal Changes in Northern Indian Population Over Smoked and Alcohol Use

Background: Oral cavity is prone for myriad of changes with advancing age as well result of environmental and life style related factors like consumption of tobacco (smoke or smokeless) and alcohol. Aim: The aim of this study was to quantify and compare the association of oral mucosal changes (OMC) with nonsmoked tobacco over smoked tobacco and alcohol. Methods: Data of 11,145 subjects from 106 health screening camps, organized in Uttar Pradesh and Rajasthan between April 2015 to June 2017 was analyzed to unveil and determine the mode of addiction and prevalence of OMC. Bivariate and multivariable models were tested for comparison and identification of factors associated with an increasing risk of developing OMC. Results: The primary symptoms were mouth ulcer in 5.6% and trismus (1.0%). The overall proportions of tobacco chewing, smoking and alcohol addiction were 12.5%, 10.7% and 2.5% respectively. The highest prevalence of smoking noted in the age-group 55-64 years (14.4%), for tobacco chewing and alcohol consumption in the age-group 25-34 years was 15.6% and 4.2% respectively ( P < 0.001). The prevalence of mouth ulcers were 20.7% among smokers and 27.8% among tobacco chewers ( P < 0.001) while the percentage of trismus 26.1% among smokers and 53.0% among tobacco chewers ( P < 0.001). Conclusion: Results of this study can be used for creating awareness among the population regarding the hazards of tobacco use. More number of studies needs to be conducted all over India to understand the prevalence and the biologic behavior of these oral premalignant lesions and its progression to invasive diseases.

Disparity Between Metro-Centric Cancer Care and Rural Outreach in India: Situational Analysis and Future Trends in Context of Developing Countries

Background: Radiation therapy is used in two-third of all patients diagnosed with cancer in any form and it has become an integral part of modern treatment strategies for many types of cancers in recent decade. Semi-urban and rural places in India lack healthcare facilities and so as the cancer care facilities. Aim: To identify the propensity of a metro-centric oncologic care in developing countries undermining the need of availability of facilities in smaller towns and cities. Methods: Data for state-wise population for 2016 and 2026 was projected using cohort component method. For the projection of cancer incidence and prevalence in 2016 and 2026, we assumed that the state-level prevalence and incidence of cancer in the year 2015 will not change over time in 2016. Data collected through telephonic interviews from the radiotherapy centers listed by Atomic Energy Regulatory Board (AERB), India. Further, we assumed few scenarios of cancer incidence and prevalence increase and projected state wise cancer burden in 2026. Results: With almost 70% population of India residing in districts and cities lacking quality health care, the situation of cancer care is much grave. India is currently equipped with only 394 RTU (Radiation Therapy Unit) against requirement of almost 1300 RTU, amounting to 0.38 RTU per million populations as per World Health Organization. The public sponsored healthcare infrastructure for cancer treatment, and research is centralized with all the resources centered in metro/major cities. Eight metro cities of India with a combined population of 140.6 million hold control of 188 RTU under their boundaries. Thus, while habitants of these eight metro cities, constituting only 10.9% of the national population, avail treatment benefit from 38% of total RTU capacity of India, rest of Indian population at 1143.8 million strengths is left prey to the wrath of cancer with just 306 machines at disposal. In comparison, the developed nations as the United States of America, Australia, and the United Kingdom fare far better in RTU availability for treatment of diagnosed cancer patients, with RTU per million population density of 12.45, 10.12 and 5.04 respectively. Similar scenario has been seen in other LMICs in world like Congo, Mongolia, Sudan, Nigeria, Nepal etc. Conclusion: We observed that wide disparity exists in India concerning RTU and cancer facility availability and density per million populations in between metro cities and rest of India and a dire need of improvement to fight against cancer which is very similar to the situation in developing countries.

Reaction Characteristics of Antiprothrombin Antibody on the Activation of Prothrombin (Sheep)

1. Prothrombin was purified by a series of steps and subsequently on DEAE-Cellu- lose chromatography and specific antibody to pure prothrombin was prepared.

2. The effect of Anti-prothrombin antibody was tested on the activation of prothrombin. The generated thrombin was assayed for its clotting function as well as for esterase activity on TAMe (Tosyl-Arginine-Methyl ester) as substrate.

3. Anti-prothrombin antibody inhibits the clotting function of generated thrombin completely but its esterase function is only partially affected.

Possible half-metallicity and variable range hopping transport in Sb-substituted Fe2TiSn Heusler alloys

The investigation of the magnetotransport properties on [Formula: see text] [Formula: see text]Sb _x with 0 [Formula: see text] 0.6 are presented in this paper. The substitution of Sb in place of Sn decreases the anti-site disorder as evident from x-ray diffraction patterns as well as from transport properties measurement. The much-disputed upturn in low temperature electrical resistivity of [Formula: see text]TiSn has been demonstrated to be a result of weak localization induced by anti-site disorder. With increased Sb substitution (⩾25%) the metallic transport behavior of [Formula: see text]TiSn changes to semiconductor-like. At low temperature, carrier transport in such compositions occurs via the variable range hopping mechanism. Moreover, a systematic increase in the anomalous Hall voltage is observed with increasing Sb-content, attributable to a side jump or Berry phase curvature effect. Electrical resistivity in the entire temperature regime hints towards half metallicity of the system. Our ab initio electronic structure calculations using generalised gradient approximation formalism further supports the results of our magnetotransport study.

A tunable coupler for superconducting microwave resonators using a nonlinear kinetic inductance transmission line

We present a tunable coupler scheme that allows us to tune the coupling strength between a feedline and a superconducting resonator in situ over a wide range. In this scheme, we shunt the feedline with a 50-Ω lumped-element nonlinear transmission line made from a 20 nm NbTiN film. By injecting a DC current, the nonlinear kinetic inductance changes and the effective impedance shunting the resonator periodically varies from a short to an open, which tunes the coupling strength and coupling quality factor Qc . We have demonstrated Qc tuning over a factor of 40, between Qc ~ 5.5 × 104 and Qc ~ 2.3 × 106, for a 4.5 GHz resonator by applying a DC current less than 3.3 mA. Our tunable coupler scheme is easy to implement and may find broad applications in superconducting detector and quantum computing/information experiments.

Autism Spectrum Disorder: the Present Perspective

The last decade has witnessed a surge of awareness about autism among the public and professionals. Much revealing research is being done on this issue and the knowledge base has improved substantially and a set of professionals are specializing on the subject, focusing on its causative factors and management. Autism being a disorder stemming from early childhood and the prevalence rate rising alarmingly over the years, Pediatricians are expected to play a vital role in early detection and early intervention in management of the problem. But, unfortunately, autism is not yet considered to be under the purview of pediatricians. As pediatricians, we are often perplexed when faced with such a different child in our office and either overlook the problem or hurry to hand him over to a psychiatrist, not trying to really identify and understand the problem as a medical entity ourselves. Hence better awareness among pediatricians is the need of the day. As specialists have worked with autism over the decades, it has become clear that: autism is a disorder that involves early development, presently there is no medical answer to autism, and the only management strategy hinges largely on effective training. The earlier the training begins the better it is for the child. It is of paramount importance to start training and bring about changes by the time the child is 18 months old. This throws up interesting new challenges to the profession of pediatrics. To identify the early warning signs of autism, it is important that Pediatricians are able to recognize the signs and symptoms of autistic spectrum disorders (ASD), have a strategy for assessing them systematically, be familiar with available tools for screening as well as developmental and educational resources.DOI: http://dx.doi.org/10.3126/jcmsn.v10i3.12775 Journal of College of Medical Sciences-Nepal, 2014, Vol-10, No-3, 37-47

Ecoepidemics overcoming the species barrier and being subject to harvesting

An ecoepidemiological model in which the disease can be transmitted from one population to another one is considered. Linear harvesting on all the populations is considered. By means of numerical simulations, the role of the epidemiological parameters as well as that of harvesting are investigated. Some relevant consequences of harvesting on the system dynamics are discovered.

Dynamics of a robust photo-induced insulator-metal transition driven by coherent and broad-band light in epitaxial films of La(0.625-y)Pr(y)Ca(0.375)MnO(3)

A dramatic drop of ≈5 orders of magnitude in the resistance (R) of La(0.175)Pr(0.45)Ca(0.375)MnO(3) epitaxial films upon exposure to optical photons derived from both continuous and pulsed lasers, as well as broad-band sources at temperatures (T) < 30 K is reported. The strength of change is a sensitive function of both the incident photon flux and temperature. Under isothermal conditions the photo-generated low resistance state persists eternally after removal of light. This non-equilibrium state is metallic, as revealed by the positive dR/dT for T ≤ T(p) (≈120 K). This electrically conducting state is presumably ferromagnetic as T(p) coincides with the temperature where a weak ferromagnetism sets in on cooling the insulating film from room temperature. To rule out the possibility of photon-induced local heating of the sample as a mechanism of the observed effects, photo-illumination experiments were performed under identical conditions on thin films of two non-charge-ordered manganites deposited on substrates of similar thermal conductivity. Our model for the observed transition encompasses a global charge-ordered state in which ferromagnetic metallic clusters of fraction p much less than the critical fraction p(c) for percolation exists at low temperatures. Photo-induced melting of the charge-ordered state increases this fraction beyond p(c) in a cumulative manner as successive pulses of light fall on the sample.

Microalbuminuria: An inexpensive, non invasive bedside tool to predict outcome in critically ill patients

This study was conducted to evaluate whether microalbuminuria on admission and after 24 hrs of admission to intensive care unit (ICU) predicts outcome as well as the Acute Physiology and Chronic Health Evaluation (APACHE) II severity illness score, the current accepted method of doing so. The study was carried out in a 20 bed mixed medical-surgical ICU of a tertiary care hospital. Of 525 consecutive adult patients with ICU stay of more than 24 hrs, 238 were included for the study. Patients with pregnancy, menstruation, anuria, macroscopic hematuria, urinary tract infection, marked proteinuria due to renal and post-renal structural diseases, were excluded. Spot urine samples were collected on admission to ICU and 24 hrs thereafter. Urine albumincreatinine ratio (ACR) was measured on ICU admission (ACR1) and after 24 hrs (ACR2) and expressed in mg/g. Patient demographics were noted on admission. For disease severity scoring, APACHE II scores were calculated. Each patient was followed up throughout their ICU stay for a maximum of 28 days and the following outcome data were obtained: ICU length of stay and ICU mortality. Of the 238 patients, 196 survived while 42 patients died in the ICU. Non-survivors had a significantly higher median ACR2 [162.7 mg/g (IQR 69.5-344.3)] in comparison to the survivors who had a median ACR2 = 54.4 mg/g (IQR 19.0-129.1) (P< 0.0001). The median ACR1 [161.0 mg/g (IQR 29.0-369.3)] of non-survivors was higher than the median ACR1 [80.4 mg/g (IQR 35.1-167.6)] of survivors but failed to reach statistical significance (P= 0.0948). In a receiver operating characteristic curve (ROC) analysis, ACR2 emerged as the best indicator of mortality [(area under curve (AUC) of ACR2 = 0.71 > AUC (ACR1) =0.58 > AUC (ΔACR) =0.55] similar to the currently used APACHE II scores (AUC = 0.78) (P=0.3). At a cutoff of 101 mg/g, ACR2 had a sensitivity of 69%, specificity of 67%, positive predictive value of 31% and a negative predictive value of 91% for predicting mortality in the critically ill patients. Absence of significant microalbuminuria at 24 hrs of ICU admission may help to predict survival in the ICU.

A study of coupling interactions in finite arbitrarily-shaped grooves in electromagnetic scattering problem

A study of coupling between finite number of general-shaped grooves in electromagnetic plane-wave scattering problem is presented. The formulation for a single groove [1] is extended to two grooves. The importance of inclusion of coupling interaction between two grooves in scattering analysis is presented and its dependence on the grooves separation distance and the angle of incident of the electromagnetic field is demonstrated quantitatively. For larger angle of incident and smaller separation distance between grooves indicate larger discrepancy between between simulation results with and without inclusion of the coupling effects. Although the results presented here considers two grooves, the formulation can be extended to arbitrary number of grooves.

Polaronic pseudogap in the metallic phase of La(0.625)Ca(0.375)MnO(3) thin films

The electronic density of states (DOS) of La(0.625)Ca(0.375)MnO(3) (LCMO) strain-free epitaxial thin films with an insulator-metal transition temperature (T(IM)) of 250 K was probed using variable-temperature scanning tunneling microscopy and spectroscopy. We find a depression in the DOS with a finite zero bias conductance (ZBC) signifying a pseudogap in the 78-310 K temperature range. With cooling, the ZBC is found to increase, indicating an increased DOS near E(F). We interpret the pseudogap as a signature of Jahn-Teller polarons while the ZBC change, in agreement with the bulk insulator-metal transition, optical Drude peak and photoemission experiments, indicates the presence of free carriers at the Fermi energy in the metallic phase. The free carriers are discussed in terms of correlated polaronic states.

Cord Blood-Derived Plasma Factor (CBPF) Potentiates the Low Cytokinetic and Immunokinetic Profile of Bone Marrow Cells in Pesticide Victims Suffering from Acquired Aplastic Anaemia (AAA): An in vitro Correlate

Cases of Acquired Aplastic Anaemia (AAA) in patients with a long history of pesticide exposure from agricultural fields have been investigated in our laboratory using an immunological approach. These patients showed moderate to severe degrees of bone marrow aplasia as a result of 9-12 years protracted exposure to pesticides which were mainly comprised of organophosphorous and organochloride compounds. The bone marrow aspirate culture was found to be severely deficient both in terms of differentiation and proliferation, and cell mediated immune function (CMI). We attempted ex vivo manipulation of the bone marrow population of patients in two different protocols: in one, stem cell factor (SCF), interleukin-3 (IL-3), and granulocyte-colony stimulating factor (G-CSF) were administered and, in the second set, cord blood-derived plasma factors (CBPF) were supplemented to evaluate the effects, if any. Simultaneously, two control groups including one for healthy normal control (N) and the second, for non-pesticide induced aplastic anaemia group of patients (NPAA) was also investigated for all the above parameters. Active colony formation and improved cellular immune activity (CMI) was observed more frequently in the CBPF treated group rather than that in the cytokine treated group. Surprisingly, administration of cytokines in the first set and CBPF in the second set triggered CD34 (+) cell generation as revealed through flow cytometric analysis (FACS). The effect was more pronounced in the second set. Investigations carried out with NPAA showed relatively insignificant effects with both cytokine and CBPF set up. The investigations indicated that AAA as induced by pesticides could be therapeutically manipulated by exogenous cytokines and growth factors and, more efficiently, by CBPF by way of immunopotentiation through microenvironmental supplementation.

Local bonding and atomic environments in Ni-catalyzed complex hydrides

The local bonding and atomic environments in the Ni-catalyzed destabilized system LiBH4/MgH2 and the quaternary borohydride-amide phase Li3BN2H8, were studied by x-ray absorption spectroscopy. In both cases the Ni catalyst was introduced as NiCl2 and a qualitative comparison of the Ni K-edge near-edge structure suggests the Ni2+ is reduced to primarily Ni0 after ball milling. The extended fine structure of the Ni K edge indicates that the Ni is coordinated by approximately 3 boron atoms with an interatomic distance of approximately 2.1 A and approximately 11 Ni atoms in a split shell at around 2.5 and 2.8 A. These results, and the lack of long-range order, suggest that the Ni is present as a disordered nanocluster with a local structure similar to that of Ni3B. In the fully hydrogenated phase of LiBH4/MgH2 a small amount Mg2NiHx was also present. Surface calculations performed using density functional theory suggest that the lowest kinetic barrier for H2 chemisorption occurs on the Ni3B(100) surface.

Bax and Bid act in synergy to bring about T11TS-mediated glioma apoptosis via the release of mitochondrial cytochrome c and subsequent caspase activation

The specific apoptotic role of T11TS has been well established in glioma animal models. T11TS specifically induces the glioma cells to die an apoptotic death via immune cross-talk with the two intracranial immune competent cells-microglia and the brain-infiltrating lymphocytes. To unearth the molecular cascades operative within the glioma cells and to some extent in the two interacting immunocytes, we had initiated studies where preliminary findings not only had indicated the involvement of death receptors but had also hinted to the involvement of other apoptotic regulators. Hence, to identify the molecular pathway of apoptosis involving other apoptotic regulators in the three cell types, the cells were studied for the intrinsic apoptotic death regulators that were engaged to maintain the mitochondrial membrane integrity. The proteins that were selected could be divided into three broad classes-the Bcl-2 family of proteins-Bid, Bax and Bcl-2; the guardian of the genome p53 and the proteins downstream of mitochondria-Apaf-1, cytochrome c, caspase-9 and caspase-3. Activated Bid as well as maximal p53 expression was observed in the first dose of T11TS thus dually activating the pro-apoptotic Bax in the first and second dose in the glioma cells. Concurrently, the pro-survival protein Bcl-2's expression level was very much down-regulated in the same two doses favoring the internal microenvironment to proceed for apoptosis. High expression of cytochrome c and Apaf-1 and the presence of active caspase-9 and active caspase-3 in all the T11TS-treated tumor-bearing groups further adjudicated apoptosis of the glioma cells with clear involvement of mitochondrial death pathway in the T11TS-treated animals. Even though expression of the apoptotic regulators remained more or less the same indicating the involvement of mitochondria in the two interacting immunocytes, the intensity of expression of these proteins was much lower than the tumor cells. The present work focuses on the mechanistic approach of how T11TS mediates apoptosis and hence is the first approach of its kind in the field of immunology where the immunotherapeutic molecule's mode of action has been worked out.

Stem cell niche, the microenvironment and immunological crosstalk

The concept of stem cells, their physiological existence, the intricate anatomical localization, the known and the unknown functions, and their exclusive utility for the purpose of regenerative medicine, are all now encompassed within an emergent question, 'how compatible these cells are immunologically?' Indeed, the medical aspects of stem cells are dependent on a large number of queries based on the basic properties of the cells. It has greatly been emphasized to probe into the basic research on stem cells before any successful therapeutic attempts are made. One of the intricate aspects of the adult stem cells is its immunological behavior in relation to the microenvironmental associates, the stromal cells in the presence of a suitable target.

Erythrocytic antioxidant defense, lipid peroxides level and blood iron, zinc and copper concentrations in dogs naturally infected with Babesia gibsoni

Babesiosis is a common tick borne disease of dogs in tropical and subtropical regions of the world caused by different species of Babesia. The present study aimed to examine erythrocyte lipid peroxide and erythrocytic antioxidant levels in dogs with clinical babesiosis, caused by Babesia gibsoni, and impact of the disease on blood iron, zinc and copper levels. The study was conducted on 10 naturally occurring cases of canine babesiosis with the history of tick infestation, erratic pyrexia, and prolonged illness. Microscopic examination of Giemsa stained peripheral blood smears confirmed B. gibsoni infection in the erythrocytes. Six apparently healthy dogs of different age, sex and breeds, brought for either health checkup or vaccination were used for comparison. Levels of erythrocytic antioxidant enzymes were significantly (P<0.01) higher in sick dogs than those of cytologically negative dogs (catalase: 0.192+/-0.024 units/mg Hb vs 0.074+/-0.004 units/mg Hb; superoxide dismutase: 0.014+/-0.0009 units/mg Hb vs 0.006+/-0.0008 units/mg Hb and lipid peroxide: 6.01+/-0.30 nmol MDA/mg Hb vs 1.89+/-0.10 nmol MDA/mg Hb). The levels of blood micronutrients were significantly low in these dogs (iron: 89.87+/-8.12 microg/g vs 126.44+/-14.65 microg/g; zinc: 3.67+/-1.85 microg/g vs 5.62+/-1.83 microg/g and copper: 0.55+/-0.63 microg/g vs 0.65+/-0.04 microg/g). The study demonstrated oxidative damage in dogs naturally infected with B. gibsoni. Low level of blood iron, zinc and copper seems to have an additional role in the genesis of anaemia and oxidative stress.

Molecular characterization and sequence variability of betasatellites associated with leaf curl disease of kenaf (hibiscus cannabinus L.) from different geographical locations of India

Leaf curl disease of kenaf (Hibiscus cannabinus L.) in India has been found to be associated with begomoviruses and betasatellites. Here, we report the molecular characterization and phylogenetic relationship of the nine isolates of betasatellites obtained from three geographical locations in India. The betasatellites coming from northern and eastern region of India shared 84.3% nucleotide sequence identity and formed two sub-clusters within the main cluster containing different isolates of Cotton leaf curl Multan betasatellite (CLCuMB) isolated in Indian subcontinent. Betasatellites coming from the southern part of India were identified as the isolates of Tomato leaf curl Joydebpur betasatellite and shared 45.2 and 44.9% sequences identity with their counterparts coming from the eastern and northern India, respectively. The present study represents the first report about the association of the leaf curl disease of kenaf with the betasatellites infecting both malvaceous and non-malvaceous crops in India.

Sol-gel synthesized SnO2 nanoparticles and their properties

Sol-gel synthesized SnO2 nanoparticles with an average size of 2.0 nm obtained at 373 K were gradually annealed to 673 K in air for 25 minutes. Sequentially taken transmission electron microscopy (TEM) images showed that particle agglomeration of these non-matrix SnO2 nanocrystals was a very slow process. The blue shifts of the band gap (approximately 2.3 eV) obtained from the optical absorbance spectra were matched with the theoretical results of the size related excitonic binding energies. These calculations also supported the observed slow grain growth. The depth sensitive hardness measurements of the thin films indicated hardness in the range of 5.03 GPa to 6.79 GPa. These undoped and non-matrix SnO2 nanoparticles were also investigated with the X-ray photoelectrons spectroscopy (XPS), atomic force microscope (AFM), X-ray diffraction spectroscopy (XRD), and ac impedance analyzer.

The other side of the coin: beneficiary effect of 'oxidative burst' upsurge with T11TS facilitates the elimination of glioma cells

Free radicals and allied molecules are the potential threats for the cellular components when they are produced in excess amount and cause different pathophysiological disorders including aging. Contrary to their detrimental effects, these molecules, in the other hand, can be utilized by the Phagocytic cells to destroy the abnormal cells and cellular components. Generation of reactive oxygen species (ROS) and nitric oxide (NO) are used as important effector molecules by Phagocytic macrophage/microglia to eliminate neoplastic cells in glioma bearing rat model. The glycoprotein T11TS/SLFA-3, by binding with CD2 receptor of macrophage/microglia, induces the generation of these reactive species when applied in three consecutive doses in glioma bearing animals. The CR3 family receptor CD11b is also correlated with the Phagocytic activity of the cells. The 'controlled' and directed production of ROS and NO by phagocytes induce cell death signals to the glioma cells and resulted in phagocytic destruction and apoptosis. The death signals generated by the free radicals and associated molecules resulted in accumulation of p53 proteins in the glioma cells. This oxidative stress induced p53 protein accumulation in neoplastic cells direct them to die by apoptosis. Therefore, the same oxidative stress causing pathophysiological problems, are used here to destroy the glioma cells by the macrophage/microglia in the delicate CNS tissue.

Clinical management of babesiosis in dogs with homeopathic Crotalus horridus 200C

Homeopathic Crotalus horridus 200C was evaluated in 13 clinical cases of babesiosis in dogs, compared with another 20 clinical cases treated with diminazine. Babesiosis is an important tropical tick-borne haemoprotozoan disease in dogs clinically manifested by anorexia, dehydration, temperature, dullness/depression, diarrhoea/constipation, pale mucosa, hepatomegaly, vomiting/nausea, splenomegaly, distended abdomen/ascites, yellow coloured urine, emaciation/weight loss, and occular discharge. The diagnosis of babesiosis was based on cytological evidence of Babesia gibsoni in freshly prepared blood smears. The dogs were treated with oral C. horridus 200C, 4 pills four times daily for 14 days (n=13) or diminazine aceturate 5 mg/kg single intramuscularly dose (n=20). All the dogs were administered 5% Dextrose normal saline at 60 ml/kg intravenously for 4 days. Initial clinical scores were similar in both groups and showed similar progressive improvement with the two treatments over 14 days. Parasitaemia also improved in both groups, but haematological values showed no change. No untoward reactions were observed. It appears that C. horridus is as effective in causing clinical recovery in moderate cases of canine babesiosis caused by Babesia gibsoni as the standard drug diminazine. Large scale randomized trials are indicated for more conclusive results.

A sequential scanning of the immune efficiency in astrocytoma (Grade I to Grade Iii), meningioma and secondary glioma patients with and without therapeutic scheduling

PURPOSE

Glioma induces immune suppression. However, data revealing the immune status in glioma patients with sequential therapeutic interventions is missing. Thus, the study aims at evaluating the sequential immune status of glioma bearing patients (Astrocytoma Grade I to Grade III) receiving conventional therapeutic measures. The results were compared with the immune status of metastatic secondary glioma and meningioma patients where there is minimal immune suppression and the effect of therapeutic intervention on the above score.

METHODS

Functional immune parameters of peripheral blood lymphocytes were assayed by CD2 receptors enumeration through E-rosetting and lymphocyte cytotoxicity assay and assessing the generation of reactive oxygen species by NBT assay of peripheral blood macrophages in patient groups bearing Astrocytoma (Grade I to Grade III), meningioma and secondary glioma.

RESULTS

Patients bearing Astrocytoma (all 3 grades) showed maximum immune suppression as compared to the normal subjects, diseased meningioma controls, and secondary glioma. Therapeutic interventions viz. radiotherapy, surgery and radiotherapy after surgery and chemotherapy could not recover the suppressed activity of the CD2 bearing lymphocytes and that of peripheral blood macrophages. However, therapeutic scheduling could recover the functional activity of the CD8 bearing lymphocytes and the CD56 NK cells from that of tumor bearing patients.

CONCLUSION

Astrocytoma and not meningioma is capable of causing immunesuppression. As the tumor progresses from Grade I to Grade III, a linear reduction in the functional efficacy of immunocytes is seen to occur. Radiotherapy, surgery, and chemotherapy also induces an inhibitory effect towards the host immune system. The inhibitory effect of tumor as well as of therapy were mainly directed towards the CD2 bearing lymphocyte population and the peripheral blood macrophage population.

Morphology and size dependent optical properties of CdS nanostructures

CdS nanoparticles with different sizes ranging from 2.5 nm to 300 nm and nanorods with aspect ratio -32 were synthesized by simple solvothermal process with a view to explore the effect of size and shape on the optical properties of these nanoforms. Solvent, temperature and the Cd source played important role in determining the morphologies and sizes of the nanocrystals. Comparative study of the optical properties of these nanoforms showed systematic changes in the optical absorption spectra with the reduction in particle size. Nanorods showed bulk like properties. Photoluminescence and Raman studies were carried out to explore the size and morphology dependent optical properties of the CdS nanoforms.

Why does ethanol induce cellular heat-shock response?

At the time of induction of the periplasmic protein alkaline phosphatase (AP) in Escherichia coli, the presence of ethanol (10% v/v) in the growth medium did not allow the induced AP to be translocated out to the periplasm. The nontransported AP was stored in the cytoplasm as the unfolded precursor form (AP with its amino-terminal signal sequence), which had no enzymatic activity. The presence of 10% v/v ethanol in the growth medium also induced the heat-shock response in E. coli, which was evident from the enhanced syntheses of several heat-shock proteins (HSPs) over their cellular basal levels. These results, in conjunction with our earlier findings on the occurrence of heat-shock response in an AP-signal sequence mutant of E. coli due to the export deficiency of AP precursor, suggest that the membrane protein precursors, stored in the cytoplasm due to the ethanol-mediated inhibition of translocation, behaved to the cells as abnormal proteins, which ultimately triggered the signal for the induction of heat-shock response in E. coli.

Synthesis and Optical Properties of CdS Nanoribbons

Rapid production of single crystalline CdS nanoribbons with hexagonal wurtzite phase has been achieved by thermal evaporation of CdS powder on Si wafers. The flow rate of the carrier (Ar) gas along with the synthesis temperature plays an important role in defining the size and shape of the CdS nanoribbons. Scanning electron and transmission electron microscopic observations revealed the nanoribbons to have a flat end as well as side surfaces which will make it ideal for optoelectronic devices such as nanolasers and light emitting diodes based on individual nanoribbons. The nanoribbons have widths within 200-400 nm and lengths approximately a few hundred micrometers. Room-temperature photoluminescence measurements show green emission centered at approximately 525 nm which may be ascribed to the near band edge emission. The Raman spectra of the CdS nanoribbons show peaks around 304, 609, 915, and 1220 cm(-1) corresponding to the first-, second-, third-, and fourth-order longitudinal optical phonon modes, respectively.

Hepatitis B infection in Eastern Indian families: need for screening of adult siblings and mothers of adult index cases

OBJECTIVES

India, with its 43 million hepatitis B virus (HBV) carriers and absence of any national immunization programme, adds a substantial number of HBV infections to the HBV carrier pool yearly. The aim of this study was to assess the spread of HBV infection in families with an infected member and to identify the family members with the highest risk of infection in our community.

METHODS

A total of 937 serum samples from 215 HBV-infected cases and 722 members of their households were screened prospectively for markers of HBV by commercial enzyme-linked immunosorbent assay.

RESULTS

Among family members, 140 (19.4%) were HBsAg positive and 272 (37.6%) were negative for HBsAg but positive for either anti HBc or anti HBs. There were 145 HBsAg-positive adults among the index cases whose 133 adult siblings, 59 spouses and 59 mothers participated in the study. Interestingly, 28.81% mothers and 28.57% adult siblings of these adult index cases were positive for HBsAg compared with only 8.75% of their spouses (P < 0.001). Only 15.2% of the HBsAg-positive women in the childbearing age group were found to be HBeAg positive.

CONCLUSIONS

Our results suggest that intrafamilial childhood horizontal transmission is important for HBV transmission in our community, and highlight the need for screening of adult siblings and mothers of adult HBsAg carriers in addition to their spouses and children.