Solvent dependent morphology and 59Co internal field NMR study of Co-aggregates synthesized by a wet chemical method.

Different shapes of Co-aggregates were synthesized via reduction of a Co salt (CoCl2·6H2O) by chemical precipitation using glycerol, ethylene glycol and ethanol as solvents. The effect of solvent on the morphology, fcc or hcp phase-content and the magnetic properties of the synthesized samples were investigated. The Co-aggregates synthesized using glycerol have a dense spherical shape and high saturation magnetization (MS), whereas ethylene glycol leads to formation of flower-shaped spherical aggregates through loose packing of smaller plate-like particles which have a moderate MS value. When ethanol was used as a solvent, a dendritic (leaf like)-shape of the aggregates with the lowest MS value was obtained. The formation of the obtained morphology of the aggregates was explained based on the size of the solvent molecule, the viscosity of the solvent and the number of polar groups (-OH) present in the solvent molecules. The magnetic domain state and domain wall dynamics of all the Co-samples were investigated using 59Co Internal Field Nuclear Magnetic Resonance (IFNMR) spectroscopy at RT and at 77 K. Through the IFNMR spectroscopy, the presence of gain boundaries, single domain particles and multi-domain particles/aggregates with domain walls associated with fcc and hcp phases were identified and quantified. We observed that the use of ethanol facilitates formation of a higher amount of hcp phase in the sample than the use of glycerol or ethylene glycol.

57Fe internal field nuclear magnetic resonance and Mössbauer spectroscopy study of Li-Zn ferrites.

We report the internal field nuclear magnetic resonance (IFNMR) and Mössbauer spectroscopy study of Li-Zn ferrites at RT. The results were supported by the IFNMR data measured at 77 K. As Zn concentration increases the IFNMR echo amplitude decreases and below certain Zn concentration no signal was detected. At RT the echo amplitude vanishes at a lower Zn concentration, whereas at 77 K, the echo amplitude does not vanish completely (except for pure Zn-ferrite). However, in Mössbauer spectroscopy at RT, we have observed magnetically ordered state of all the Li-Zn ferrite samples. This discrepancy could be related to the difference between the time scale of detection of the spins by Mössbauer spectroscopy (10-7-10-10 s) and NMR spectroscopy (10-6 s). Hence, sensitivity of zero-field NMR depends on the magnetic hyperfine field, temperature and abundance of the magnetic cations at the lattice of the spinel ferrites. We have demonstrated that the 'two-equal-pulses' sequence leads to higher echo signal than the spin echo pulse sequence due to the presence of distribution of internal magnetic fields throughout the material. We obtained a limiting value for the fraction of spins needed to produce an echo signal at a particular temperature and at a particular site of the Li-Zn ferrite spinels that can be sensitively detected by pulsed IFNMR technique.

Genetic characterization of the glycoprotein G of Chandipura viruses in India with emphasis on an outbreak of 2015.

Chandipura virus (CHPV) is found to be associated with sporadic encephalitis outbreaks in humans in India since 1965. We report here, the investigation of CHPV activity during the period of June-August 2015 in the state of Gujarat, which revealed 24.44% positivity among 45 referred encephalitis cases. Phylogenetic study of the G gene sequences of strains from Gujarat 2015 along with available sequences of additional strains from different geographical locations and isolation years (1965-2015), indicated the relatedness of the 2015 strain to a group of the CHPV prototype strain of 1965 and the earliest outbreak strains of 2003. Analyses of selection pressure in the G gene revealed positively selected sites within the signal peptide region and a putative CHPV epitope. These results indicate a probable role of G protein-based immune selection and underline the need for continued surveillance to monitor genetic and antigenic variations in the CHPV.

Tunica vaginalis pedicle flap for repair of ruptured testis: A single-center experience with four patients.

Management of testicular rupture with a large tunical defect may not be feasible without excision of viable tissue. This study describes the use of a vascularized tunica vaginalis flap, without debridement of viable tissue, in four adolescents. Postoperative ultrasound showed good blood flow and 80% volume of the contralateral testis in two cases. Postoperative exam revealed normal exam and ultrasonographic appearance in three patients, the fourth was demonstrated to be small and undescended during evaluation of contralateral testicular torsion. This approach is recommended in cases of large tunical defects, as it avoids the debridement of viable testicular tissue.

Development of a novel rapid micro-neutralization ELISA for the detection of neutralizing antibodies against Chandipura virus.

BACKGROUND: Chandipura virus (CHPV) is a leading cause of acute encephalitis with high mortality in paediatric population in India. A micro-neutralization ELISA (MN-ELISA) assay was developed for the detection of neutralizing antibodies (Nab) against CHPV. This novel method gives read-out in the form of ELISA optical density (OD) values and has a shorter turn-around time (TAT) as compared to the conventional cytopathic effect (CPE)-based neutralization assay (MN-CPE). The assay was developed using an Indian strain of CHPV. During the development of the assay different parameters such as cell count, dilution of primary and secondary antibodies and time point for the test termination were optimized. The new and conventional assays were run in parallel where known positive and negative human serum samples were used as test controls. The conventional MN-CPE was terminated at 48h post-infection (p.i.) and stained with Amido black, while in the new assay, MN-ELISA was terminated at pre-determined 18h p.i. and the infected cells were fixed with acetone, followed by in-situ ELISA. Results of both the assays were compared. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the new test was 100% when compared with the conventional MN-CPE method as a 'gold standard'. The MN-ELISA showed two-fold higher antibody titer in one sample and one sample was additionally positive than MN-CPE ELISA. CONCLUSION: The MN-ELISA is rapid, more sensitive and read-out of results is by measurement of OD, which could be more accurate than manual observation of reduction in CPE. This novel test could be used as an alternative to the conventional MN-CPE based assay in sero-surveillance and in future vaccine studies.

Diagnostic potential of monoclonal antibodies against the capsid protein of chikungunya virus for detection of recent infection.

Chikungunya fever is self-limiting. However, neurological and hemorrhagic complications have been seen in recent outbreaks. The clinical manifestations of this disease are similar to those of dengue virus infection, indicating the need for differential diagnosis in areas such as India, which are endemic for both viruses. The aim of the present study was to develop monoclonal antibodies (MAbs) against Chikungunya virus (CHIKV) and assess their use in MAb-based IgM capture ELISA (MAC ELISA). The ELISA detects CHIKV-specific IgM antibodies, a marker of recent infection, in a patient's serum. One IgG1 and two IgM isotype hybrids were obtained. All of the subclones derived from the IgG1 hybrid recognized the C protein of CHIKV. The anti-C MAb ClVE4/D9 was the most promising as a detector antibody in MAC ELISA (C-MAb ELISA) yielding higher positive-to-negative (P/N) ratios. When compared with the CHIKV MAC ELISA kit developed by the National Institute of Virology (NIV), Pune (NIV MAC ELISA), the sensitivity of the test was 87.01 % with 100 % specificity. The positive and negative predictive values (PPV and NPV) were 100 % and 94.47 %, respectively. In precision testing, standard deviation (SD) and coefficient of variation (% CV) values of the C-MAb ELISA were within acceptable limits. The C-MAb ELISA detected anti-CHIKV IgM in serum of patients up to five months after the onset of infection, indicating that anti-C MAbs have strong potential for use in MAC ELISA to detect recent CHIKV infection.

Study of molecular dynamics and cross relaxation in tetramethylammonium hexafluorophosphate (CH(3))(4)NPF(6) by (1)H and (19)F NMR.

(CH(3))(4)NPF(6) is studied by NMR measurements to understand the internal motions and cross relaxation mechanism between the heterogeneous nuclei. The spin lattice relaxation times (T(1)) are measured for (1)H and (19)F nuclei, at three (11.4, 16.1 and 21.34 MHz) Larmor frequencies in the temperature range 350-50K and (1)H NMR second moment measurements at 7 MHz in the temperature range 300-100K employing home made pulsed and wide-line NMR spectrometers. (1)H NMR results are attributed to the simultaneous reorientations of both methyl and tetramethylammonium groups and motional parameters are evaluated. (19)F NMR results are attributed to cross relaxation between proton and fluorine and motional parameters for the PF(6) group reorientation are evaluated.

1H NMR study of internal motions and quantum rotational tunneling in (CH3)4NGeCl3.

(CH3)4NGeCl3 is prepared, characterized and studied using 1H NMR spin lattice relaxation time and second moment to understand the internal motions and quantum rotational tunneling. Proton second moment is measured at 7 MHz as function of temperature in the range 300-77 K and spin lattice relaxation time (T1) is measured at two Larmor frequencies, as a function of temperature in the range 270-17 K employing a homemade wide-line/pulsed NMR spectrometers. T1 data are analyzed in two temperature regions using relevant theoretical models. The relaxation in the higher temperatures (270-115 K) is attributed to the hindered reorientations of symmetric groups (CH3 and (CH3)4N). Broad asymmetric T1 minima observed below 115 K down to 17 K are attributed to quantum rotational tunneling of the inequivalent methyl groups.

Study of molecular reorientation and quantum rotational tunneling in tetramethylammonium selenate by 1H NMR.

1H NMR spin-lattice relaxation time measurements have been carried out in [(CH3)4N]2SeO4 in the temperature range 389-6.6 K to understand the possible phase transitions, internal motions and quantum rotational tunneling. A broad T1 minimum observed around 280 K is attributed to the simultaneous motions of CH3 and (CH3)4N groups. Magnetization recovery is found to be stretched exponential below 72 K with varying stretched exponent. Low-temperature T1 behavior is interpreted in terms of methyl groups undergoing quantum rotational tunneling.

Growth of respiratory syncytial virus in mink lung epithelial cells.

Mink lung epithelial cells (Mv-1-Lu) were tested for their ability to support the growth and serial passage of respiratory syncytial virus (RSV) in vitro. Indian isolates of RSV induced distinctive cytopathic effect with typical rounding of cells followed by detachment with more than 50 per cent cells showing bright fluorescence using anti-RSV monoclonal antibodies in immunofluorescence test. Serial passage of RSV was possible in Mv-1-Lu cells without loss of sensitivity of the cells for virus growth. Titration of cell associated virus and virus released in the supernatant indicated that 60 per cent of the virus was released in the supernatant, and 40 per cent remained cell associated. Transmission electron microscopic studies of negatively stained RSV particles and ultra-thin sections of RSV infected Mv-1-Lu cells showed roughly spherical particles with club shaped projections, budding from the cytoplasmic membrane. These results indicate that Mv-1-Lu cell line is suitable for the growth and propagation of RSV.

Simultaneous flow cytometric analysis of cell surface markers and telomere length: analysis of human tonsilar B cells.

Telomere Flow FISH is a recently developed method which allows the measurement of telomere length in purified subsets of cells using flow cytometry. However, the harsh conditions required for flow FISH have precluded its use with conventional cell surface staining, thus limiting its utility for large scale clinical studies. We have now developed a method which permits simultaneous analysis of cell surface markers along with telomere length estimation by flow cytometry. This new assay employs the covalent crosslinking of monoclonal antibodies conjugated with a heat stable fluorochrome to the cell surface prior to flow FISH. Using this technique we have confirmed that human germinal center B cells (IgD(-)/CD38(+)) have dramatically longer telomeres than pre-germinal center founder B cells (IgD(+)/CD38(+)). This approach simplifies the analysis of complex cell populations and will facilitate widespread investigation of telomere length in health and disease states.

Ig V gene mutation status and CD38 expression as novel prognostic indicators in chronic lymphocytic leukemia.

Cellular immunophenotypic studies were performed on a cohort of randomly selected IgM(+) B-chronic lymphocytic leukemia (B-CLL) cases for which Ig V(H) and V(L) gene sequences were available. The cases were categorized based on V gene mutation status and CD38 expression and analyzed for treatment history and survival. The B-CLL cases could be divided into 2 groups. Those patients with unmutated V genes displayed higher percentages of CD38(+) B-CLL cells (>/=30%) than those with mutated V genes that had lower percentages of CD38(+) cells (<30%). Patients in both the unmutated and the >/=30% CD38(+) groups responded poorly to continuous multiregimen chemotherapy (including fludarabine) and had shorter survival. In contrast, the mutated and the <30% CD38(+) groups required minimal or no chemotherapy and had prolonged survival. These observations were true also for those patients who stratified to the Rai intermediate risk category. In the mutated and the <30% CD38(+) groups, males and females were virtually equally distributed, whereas in the unmutated and the >/=30% CD38(+) groups, a marked male predominance was found. Thus, Ig V gene mutation status and the percentages of CD38(+) B-CLL cells appear to be accurate predictors of clinical outcome in B-CLL patients. These parameters, especially CD38 expression that can be analyzed conveniently in most clinical laboratories, should be valuable adjuncts to the present staging systems for predicting the clinical course in individual B-CLL cases. Future evaluations of new therapeutic strategies and drugs should take into account the different natural histories of patients categorized in these manners.

Antiproliferative activity of conditioned medium from lymphocytes of neuroblastoma (NB) patient and inhibition with NB serum.

Neuroblastoma (NB) is a pediatric malignancy and results in high mortality rate. Cellular immunity has been shown to play an important role in killing tumors 'in vitro'. Human lymphocytes were activated in vitro with phytohaemagglutinin (PHA) and the effect of supernatants collected at 24, 48, 72 and 96 h were tested on proliferation of human NB cell line-SK-N-MC and glioma cell line U87-MG. The SK-N-MC cells were observed to be more susceptible to the supernatants compared to U87-MG with higher inhibition of proliferation as evaluated by [3H]thymidine incorporation (P < 0.05 for 24 and 72 h and P < 0.0005 for 48 and 96 h). Conditioned medium from lymphocytes of NB patient collected at 48 and 96 h after activation inhibited proliferation (P < 0.005) of SK-N-MC cells. The presence of serum from NB patient decreased the antiproliferative activity of supernatants from normal lymphocytes and NB patient's autologous lymphocytes (P < 0.01). This preliminary data demonstrates the capability of the activation of lymphocytes from NB patient undergoing aggressive multiagent chemotherapy and controlling proliferation of tumor cells on one hand and the role of serum from NB patient in abrogating to a certain extent the effect of activated immune cells thereby protecting tumor cells, on the other hand. Both these aspects need to considered with equal importance to study mechanisms in designing strategies for immune therapies.

Comparison of oversensing during bradycardia pacing in two types of implantable cardioverter-defibrillator systems.

BACKGROUND: During bradycardia pacing in Ventritex Cadence (Models V-100 and V-110) implantable cardioverter-defibrillators, amplifier gain is maximal and oversensing and false tachyarrhythmia detection have been reported. Newer Ventritex devices (Cadet, Model V-115 and Contour, Model V-145) have a modified automatic gain control that may minimize oversensing. METHODS AND RESULTS: We prospectively studied 50 patients (22 with Cadence, 28 with Cadet or Contour). Electrograms were evaluated for oversensing during bradycardia pacing. The bradycardia pacing refractory period required to prevent oversensing of T waves of paced beats and the time and number of beats required to achieve minimum gain after cessation of pacing were assessed. The bradycardia pacing refractory period could be left at its default setting of 350 ms in only 15 (30%) of 50 patients. The mean bradycardia pacing refractory period required to avoid oversensing of paced T waves was 386+/-32 ms. During pacing, oversensing of nonpaced T waves was seen in 12 (24%) devices, with similar incidence in Cadence devices (18%) and Cadet and Contour devices (29%, p = not significant). The time and number of beats to achieve minimum gain after pacing were longer in Cadence devices (19.0+/-4.5 vs 4.6+/-1.2 sec; 21.3+/-3.3 vs 5.0+/-0.4 beats, both p < 0.001). CONCLUSIONS: The incidence of oversensing at maximum gain is similar in both types of devices, but more rapid changes in autogain levels in the newer devices may reduce the likelihood of false tachyarrhythmia detection.

Radiofrequency catheter ablation of idiopathic left ventricular tachycardia originating in the left anterior fascicle.

Radiofrequency catheter ablation has been used to treat idiopathic left ventricular tachycardia with high success rates. The majority of reported cases have exhibited the typical findings of right bundle branch block morphology with left axis deviation and originate from within or near the left posterior fascicle. We report a case of idiopathic left ventricular tachycardia originating from within or near the left anterior fascicle, which was successfully ablated using a local Purkinje potential as a guide.

Strain analysis and epitope mapping of West Nile virus using monoclonal antibodies.

Monoclonal antibodies (MAbs) against an Indian strain (804994) and an Egyptian strain (E 101) of West Nile virus (WNV) were prepared in mice. Nine MAbs against the 804994 strain and 5 MAbs against E 101 strain were obtained. All 14 MAbs reacted with the envelope (E) protein of WNV in an immunoblot assay. They were tested by an enzyme-linked immunosorbent assay (ELISA) for their cross-reactivity with WNV, Japanese encephalitis virus (JEV) and Dengue-2 virus (DEN-2), and for their reactivity in haemagglutination-inhibition (HAI) test. Based on these results MAbs were broadly grouped into three groups, namely WNV-specific HAI-positive, WNV-JEV cross-reactive HAI-positive, and WNV-JEV cross-reactive HAI-negative MAbs. The antigenic cross-reactivity between twelve WNV strains isolated from different geographical regions and their respective hosts was assessed using these MAbs in HAI and complement fixation (CF) tests. The strain analysis by CF distinguished Indian from South African strains. However, a similarity between some Indian and South African strains in HAI was observed. E 101 strain appeared to have antigenic similarity with Indian as well as South African strains. Overall it appears that antigenically similar strains of WNV are prevalent in India. A single heterogenous domain was apparent on the epitope map of WNV deduced by ELISA additivity test.

Electrical activation during ventricular fibrillation in the subacute and chronic phases of healing canine myocardial infarction.

BACKGROUND: Little information is available regarding the effects of myocardial infarction on the characteristics of ventricular fibrillation (VF). Epicardial activation during VF can be characterized by the cycle length and by the characteristics of activation wave fronts. METHODS AND RESULTS: VF was induced by programmed stimulation in 6 dogs with subacute healing (1 week) myocardial infarction (MI), 5 dogs with chronic (8 week) healing MI, and 6 dogs without MI. Using a plaque electrode array with a 2.5-mm interelectrode distance, 112 electrograms were recorded and 91 vector loops were created for each cycle of VF from either the anterior (infarcted) or lateral (noninfarcted) wall. Direction of maximum epicardial activation was determined at each site for the first 10 cycles of VF (early) and for 10 cycles after 5 seconds of VF (late). Wave front size was determined based on a similarity in epicardial activation directions within a given area and by a statistical analysis that determined the degree of spatial linking at varying distances over the recording plaque. VF cycle length was defined as the mean interval of 10 consecutive local activation times. Differences among groups and differences between the anterior and posterolateral walls were determined by ANOVA. The mean wave front area was significantly larger in the presence of subacute MI (97 +/- 4 mm2, early; 78 +/- 3 mm2, late) or chronic MI (94 +/- 5 mm2, early; 78 +/- 5 mm2, late) than in noninfarcted animals (73 +/- 5 mm2, early; 61 +/- 3 mm2, late). The degree of linking of epicardial activation directions was similar in the three groups at distances of 2.5 and 5.0 mm but was lower at a distance of 7.5 mm among animals without infarction, confirming a smaller wave front size and suggesting less organization of activation. VF cycle length was significantly longer in the presence of infarction (98 +/- 5 ms, normal control animals; 121 +/- 13 ms, subacute MI; 127 +/- 13 ms, chronic MI). VF cycle length was significantly longer over the anterior than the lateral wall in the presence of subacute MI (131 +/- 8 ms, anterior; 109 +/- 5 ms, lateral) or chronic MI (136 +/- 9 ms, anterior; 119 +/- 6 ms, lateral) but not in noninfarcted animals (99 +/- ms, anterior; 97 +/- 5 ms, lateral). The prolongation of VF cycle length among animals with infarction was associated with slower estimated conduction velocities during VF. CONCLUSIONS: During VF, in animals with subacute or chronic healing MI, (1) the size of activation wave fronts is larger, (2) the cycle length of VF is longer, (3) the conduction velocities are slower, and (4) the degree of organization is greater than in control animals. Thus, the characteristics of VF throughout the heart are altered by the presence of regional myocardial infarction. The implications of these findings for the initiation and maintenance of VF in the presence of different underlying myocardial substrates require further study.

Effect of increased drive-train stimulus intensity on dispersion of ventricular refractoriness.

BACKGROUND: Most studies evaluating the effects of high-intensity drive-train (S1) stimulation on the measurement of the ventricular effective refractory period (VERP) demonstrated a shortening of the VERP. Because this effect may be due to the local release of catecholamines, VERP shortening would be expected to occur only near the site of stimulation. Local shortening in the VERP should then result in an increased dispersion of refractoriness during high-intensity drive-train stimulation. Thus, this study evaluated the spatial distribution of the VERP shortening resulting from high-intensity S1 stimulation and its effect on dispersion of refractoriness. METHODS AND RESULTS: Three groups of patients were studied. In group 1, 10 subjects without structural heart disease had VERP determinations performed at the right ventricular apex (RVA) and outflow tract (RVOT) while the S1 site was changed to evaluate the effects of low-intensity S1 stimulation on the measured VERP. In group 2, the effect of high-intensity S1 stimulation on the VERP was studied 0, 7, 14, and 21 mm away from the S1 site to measure the spatial distribution of VERP shortening and the effect on dispersion of refractoriness; 10 additional subjects without structural heart disease made up group 2. Because increased dispersion of refractoriness may be deleterious in certain clinical situations, the effect of high-intensity S1 stimulation was studied in group 3, which comprised 10 subjects with chronically implanted transvenous defibrillators; noninvasive measurements of the VERP through the chronic lead were made while the S1 stimulus intensity was varied from low to high intensity. All VERP determinations were performed during continuous pacing by use of an incremental method and a low stimulus intensity for the extrastimulus. In group 1, the RVA VERPs were 218 +/- 9 and 214 +/- 10 ms when the S1 site was the RVA and RVOT, respectively (P = NS). The RVOT VERPs were also unchanged when the S1 site was changed from the RVOT to the RVA. In group 2, high-intensity S1 changed the VERP from 224 +/- 8 (at twice the threshold) to 203 +/- 10 ms (P < .01), 220 +/- 11 to 209 +/- 12 ms (P < .01), 222 +/- 12 to 221 +/- 12 ms, and 220 +/- 11 to 221 +/- 11 ms at 0, 7, 14, and 21 mm away from the S1 site, respectively. High-intensity S1 stimulation led to an increase in the dispersion of refractoriness from 13 +/- 4 to 22 +/- 9 ms (P = .006). In group 3, high-intensity S1 stimulation shortened the VERP from 309 +/- 23 to 285 +/- 30 ms (P = .0003). CONCLUSIONS: Low-intensity S1 stimulation has no significant effect on the VERP. High-intensity S1 stimulation shortens the refractory period maximally at the site of stimulation; the VERP shortening dissipates between 7 and 14 mm away from the site of S1 stimulation, resulting in an increased dispersion of refractoriness. The local VERP shortening with high-intensity stimulation is noted in patients with chronically implanted defibrillator leads, which may have implications for the mechanism of proarrhythmia during high-intensity stimulation.