Varied Immune Response to FVIII: Presence of Proteolytic Antibodies Directed to Factor VIII in Different Human Pathologies

The versatility of antibodies is demonstrated by the various functions that they mediate such as neutralization, agglutination, fixation of the complement and its activation, and activation of effector cells. In addition to this plethora of functions, antibodies are capable of expressing enzymatic activity. Antibodies with catalytic function are a result of the productive interplay between the highly evolved machinery of the immune system and the chemical framework used to induce them (antigens). Catalytic antibodies are immunoglobulins with an ability to catalyze the reactions involving the antigen for which they are specific. Catalytic immunoglobulins of the IgM and IgG isotypes have been detected in the serum of healthy donors. In addition, catalytic immunoglobulins of the IgA isotype have been detected in the milk of healthy mothers. Conversely, antigen-specific hydrolytic antibodies have been reported in a number of inflammatory, autoimmune, and neoplastic disorders. The pathophysiological occurrence and relevance of catalytic antibodies remains a debated issue. Through the description of the hydrolysis of coagulation factor VIII as model target antigen, we propose that catalytic antibodies directed to the coagulation factor VIII may play a beneficial or a deleterious role depending on the immuno-inflammatory condition under which they occur.

Alveolar macrophages as accessory cells for human gamma delta T cells activated by Mycobacterium tuberculosis.

Alveolar macrophages form the first line of defense against inhaled droplets containing Mycobacterium tuberculosis by controlling mycobacterial growth and regulating T cell responses. CD4+ and gamma delta T cells, two major T cell subsets activated by M. tuberculosis, require accessory cells for activation. However, the ability of alveolar macrophages to function as accessory cells for T cell activation remains controversial. We sought to determine the ability of alveolar macrophages to serve as accessory cells for resting (HLA-DR-, IL-2R-) and activated (HLA-DR+, IL-2R+) gamma delta T cells in response to M. tuberculosis and its Ag, and to compare accessory cell function for gamma delta T cells of alveolar macrophages and blood monocytes obtained from the same donor. Alveolar macrophages were found to serve as accessory cells for both resting and activated gamma delta T cells in response to M. tuberculosis Ag. At high alveolar macrophage to T cell ratios (> 3:1), however, expansion of resting gamma delta T cells was inhibited by alveolar macrophages. The inhibition of resting gamma delta T cells by alveolar macrophages was dose-dependent, required their presence during the first 24 h, and was partially overcome by IL-2. Alveolar macrophages did not inhibit activated gamma delta T cells even at high accessory cell to T cell ratios, and alveolar macrophages functioned as well as monocytes as accessory cells. Monocytes were not inhibitory for either resting or activated gamma delta T cells. These findings support the following model. In the normal alveolus the alveolar macrophage to T cell ratio is > or = 9:1, and therefore the threshold for resting gamma delta T cell activation is likely to be high. Once a nonspecific inflammatory response occurs, such as after invasion by M. tuberculosis, this ratio is altered, favoring gamma delta T cell activation by alveolar macrophages.

Mechanism of lectin-cell interactions: thermodynamic and kinetic analysis of the binding of winged bean acidic lectin (WBA II) to human erythrocytes

In order to identify the forces involved in the binding and to understand the mechanism involved, equilibrium and kinetic studies were performed on the binding of the winged bean acidic lectin to human erythrocytes. The magnitudes of delta S and delta H were positive and negative respectively, an observation differing markedly from the lectin-simple sugar interactions where delta S and delta H are generally negative. Analysis of the sign and magnitudes of these values indicate that ionic and hydrogen bonded interactions prevail over hydrophobic interactions resulting in net -ve delta H (-37.12 kJ.mol-1) and +ve delta S (14.4 J.mole-1 K-1 at 20 degrees C), thereby suggesting that this entropy driven reaction also reflects conformational changes in the lectin and/or the receptor. Presence of two kinds of receptors for WBA II on erythrocytes, as observed by equilibrium studies, is consistent with the biexponential dissociation rate constants (at 20 degrees C K1 = 1.67 x 10(-3) M-1 sec-1 and K2 = 11.1 x 10(-3) M-1 sec-1). These two rate constants differed by an order of magnitude accounting for the difference in the association constants of the two receptors of WBA II. However, the association process remains monoexponential suggesting no observable difference in the association rates of the lectin molecule with both the receptors, under the experimental conditions studied. The thermodynamic parameters calculated from kinetic data correlate well with those observed by equilibrium. A two-step binding mechanism is proposed based on the kinetic parameters for WBA II-receptor interaction

Antibodies against the extracellular domain of human Notch1 receptor reveal the critical role of epidermal-growth-factor-like repeats 25-26 in ligand binding and receptor activation

The Notch signalling pathway is implicated in a wide variety of cellular processes throughout metazoan development. Although the downstream mechanism of Notch signalling has been extensively studied, the details of its ligand-mediated receptor activation are not clearly understood. Although the role of Notch ELRs EGF (epidermal growth factor)-like-repeats] 11-12 in ligand binding is known, recent studies have suggested interactions within different ELRs of the Notch receptor whose significance remains to be understood. Here, we report critical inter-domain interactions between human Notch1 ELRs 21-30 and the ELRs 11-15 that are modulated by calcium. Surface plasmon resonance analysis revealed that the interaction between ELRs 21-30 and ELRs 11-15 is similar to 10-fold stronger than that between ELRs 11-15 and the ligands. Although there was no interaction between Notch 1 ELRs 21-30 and the ligands in vitro, addition of pre-clustered Jagged1Fc resulted in the dissociation of the preformed complex between ELRs 21-30 and 11-15, suggesting that inter-domain interactions compete for ligand binding. Furthermore, the antibodies against ELRs 21-30 inhibited ligand binding to the full-length Notch1 and subsequent receptor activation, with the antibodies against ELRs 25-26 being the most effective. These results suggest that the ELRs 25-26 represent a cryptic ligand-binding site which becomes exposed only upon the presence of the ligand. Thus, using specific antibodies against various domains of the Notch1 receptor, we demonstrate that, although ELRs 11-12 are the principal ligand-binding site, the ELRs 25-26 serve as a secondary binding site and play an important role in receptor activation.

Non-invasive human breath sensor

In this paper, the design and development of a novel low-cost, non-invasive type sensor suitable for human breath sensing is reported. It can be used to detect respiratory disorders like bronchial asthma by analyzing the recorded breathing pattern. Though there are devices like spirometer to diagnose asthma, they are very inconvenient for patient's use because patients are made to exhale air through mouth forcefully. Presently developed sensor will overcome this limitation and is helpful in the diagnosis of respiratory related abnormalities. Polyvinylidene fluoride (PVDF) film in cantilever configuration is used as a sensing element to form the breath sensor. Two identical sensors are mounted on a spectacle frame, such that the tidal flow of inhaled and exhale air will impinge on sensor, for sensing the breathing patterns. These patterns are recorded, filtered, analyzed and displayed using CRO. Further the sensor is calibrated using a U-tube water manometer. The added advantage of piezoelectric type sensing element is that it is self powered without the need of any external power source.

A landscape-level assessment of Asian elephant habitat, its population and elephant-human conflict in the Anamalai hill ranges of southern Western Ghats, India

Spatial information at the landscape scale is extremely important for conservation planning, especially in the case of long-ranging vertebrates. The biodiversity-rich Anamalai hill ranges in the Western Ghats of southern India hold a viable population for the long-term conservation of the Asian elephant. Through rapid but extensive field surveys we mapped elephant habitat, corridors, vegetation and land-use patterns, estimated the elephant population density and structure, and assessed elephant-human conflict across this landscape. GIS and remote sensing analyses indicate that elephants are distributed among three blocks over a total area of about 4600 km(2). Approximately 92% remains contiguous because of four corridors; however, under 4000 km2 of this area may be effectively used by elephants. Nine landscape elements were identified, including five natural vegetation types, of which tropical moist deciduous forest is dominant. Population density assessed through the dung count method using line transects covering 275 km of walk across the effective elephant habitat of the landscape yielded a mean density of 1.1 (95% Cl = 0.99-1.2) elephant/km(2). Population structure from direct sighting of elephants showed that adult male elephants constitute just 2.9% and adult females 42.3% of the population with the rest being subadults (27.4%), juveniles (16%) and calves (11.4%). Sex ratios show an increasing skew toward females from juvenile (1:1.8) to sub-adult (1:2.4) and adult (1:14.7) indicating higher mortality of sub-adult and adult males that is most likely due to historical poaching for ivory. A rapid questionnaire survey and secondary data on elephant-human conflict from forest department records reveals that villages in and around the forest divisions on the eastern side of landscape experience higher levels of elephant-human conflict than those on the western side; this seems to relate to a greater degree of habitat fragmentation and percentage farmers cultivating annual crops in the east. We provide several recommendations that could help maintain population viability and reduce elephant-human conflict of the Anamalai elephant landscape. (C) 2013 Deutsche Gesellschaft far Saugetierkunde. Published by Elsevier GmbH. All rights reserved.

Quantifying Vocal Mimicry in the Greater Racket-Tailed Drongo: A Comparison of Automated Methods and Human Assessment

Objective identification and description of mimicked calls is a primary component of any study on avian vocal mimicry but few studies have adopted a quantitative approach. We used spectral feature representations commonly used in human speech analysis in combination with various distance metrics to distinguish between mimicked and non-mimicked calls of the greater racket-tailed drongo, Dicrurus paradiseus and cross-validated the results with human assessment of spectral similarity. We found that the automated method and human subjects performed similarly in terms of the overall number of correct matches of mimicked calls to putative model calls. However, the two methods also misclassified different subsets of calls and we achieved a maximum accuracy of ninety five per cent only when we combined the results of both the methods. This study is the first to use Mel-frequency Cepstral Coefficients and Relative Spectral Amplitude - filtered Linear Predictive Coding coefficients to quantify vocal mimicry. Our findings also suggest that in spite of several advances in automated methods of song analysis, corresponding cross-validation by humans remains essential.

Histone H3K9 acetylation level modulates gene expression and may affect parasite growth in human malaria parasite Plasmodium falciparum

Three-dimensional positioning of the nuclear genome plays an important role in the epigenetic regulation of genes. Although nucleographic domain compartmentalization in the regulation of epigenetic state and gene expression is well established in higher organisms, it remains poorly understood in the pathogenic parasite Plasmodium falciparum. In the present study, we report that two histone tail modifications, H3K9Ac and H3K14Ac, are differentially distributed in the parasite nucleus. We find colocalization of active gene promoters such as Tu1 (tubulin-1 expressed in the asexual stages) with H3K9Ac marks at the nuclear periphery. By contrast, asexual stage inactive gene promoters such as Pfg27 (gametocyte marker) and Pfs28 (ookinete marker) occupy H3K9Ac devoid zones at the nuclear periphery. The histone H3K9 is predominantly acetylated by the PCAF/GCN5 class of lysine acetyltransferases, which is well characterized in the parasite. Interestingly, embelin, a specific inhibitor of PCAF/GCN5 family histone acetyltransferase, selectively decreases total H3K9Ac acetylation levels (but not H3K14Ac levels) around the var gene promoters, leading to the downregulation of var gene expression, suggesting interplay among histone acetylation status, as well as subnuclear compartmentalization of different genes and their activation in the parasites. Finally, we found that embelin inhibited parasitic growth at the low micromolar range, raising the possibility of using histone acetyltransferases as a target for antimalarial therapy.