18 research outputs found
Determination of mycophenolic acid in human plasma by ultra performance liquid chromatography tandem mass spectrometry
AbstractA simple, sensitive and high throughput ultra performance liquid chromatography tandem mass spectrometry method has been developed for the determination of mycophenolic acid in human plasma. The method involved simple protein precipitation of MPA along with its deuterated analog as an internal standard (IS) from 50µL of human plasma. The chromatographic analysis was done on Acquity UPLC C18 (100mm×2.1mm, 1.7µm) column under isocratic conditions using acetonitrile and 10mM ammonium formate, pH 3.00 (75:25, v/v) as the mobile phase. A triple quadrupole mass spectrometer operating in the positive ionization mode was used for quantitation. In-source conversion of mycophenolic glucuronide metabolite to the parent drug was selectively controlled by suitable optimization of cone voltage, cone gas flow and desolvation temperature. The method was validated over a wide concentration range of 15–15000ng/mL. The mean extraction recovery for the analyte and IS was >95%. Matrix effect expressed as matrix factors ranged from 0.97 to 1.02. The method was successfully applied to support a bioequivalence study of 500mg mycophenolate mofetil tablet in 72 healthy subjects
Regional variation in the composition and structure of mixed-species bird flocks in the Western Ghats and Sri Lanka
Mixed-species bird flocks are attractive models for the
investigation of geographical variation in animal communities,
as they represent a subset of the avifauna in
most forested regions of the world. Yet studies of the
regional variation in flock size and the composition of
flocks are few, due to the predominance of studies
carried out at single study site. Here, we review nine
studies of mixed-species flocks conducted at 16 sites
along the Western Ghats in India and in Sri Lanka.
We find that flock size varies as much within this
region as it does globally, with observation time being
a confounding variable. Flock composition, however,
is predictably related to elevation. Flocks at high elevations
(>1200 m) in the Western Ghats strongly resemble
flocks at high elevations in the mountain
ranges of Sri Lanka in their composition, especially at
the family level. We compare these flocks to flocks of
other regions and make recommendations on study
methodology that can facilitate comparisons across
studies
Positive relationships between association strength and phenotypic similarity characterize the assembly of mixed-species bird flocks worldwide
Competition theory predicts that local communities should consist of species that are more dissimilar than expected by chance. We find a strikingly different pattern in a multicontinent data set (55 presence-absence matrices from 24 locations) on the composition of mixed-species bird flocks, which are important sub-units of local bird communities the world over. By using null models and randomization tests followed by meta-analysis, we find the association strengths of species in flocks to be strongly related to similarity in body size and foraging behavior and higher for congeneric compared with noncongeneric species pairs. Given the local spatial scales of our individual analyses, differences in the habitat preferences of species are unlikely to have caused these association patterns; the patterns observed are most likely the outcome of species interactions. Extending group-living and social-information-use theory to a heterospecific context, we discuss potential behavioral mechanisms that lead to positive interactions among similar species in flocks, as well as ways in which competition costs are reduced. Our findings highlight the need to consider positive interactions along with competition when seeking to explain community assembly
Roost selection by Indian peafowl (Pavo cristatus) in Gir forest, India
Volume: 93Start Page: 25End Page: 2
Formulation of medium constituents by multiresponse analysis of central composite design to enhance chitinase production in <i>Pantoea dispersa</i>
1123-1131In the present study, a high chitinase
producing strain Pantoea dispersa was isolated from the sea dumps at Bhavnagar, India.
Chitin, urea, CaCl2 and MgSO4.7H2O were
variables used in central composite design for chitinase production. Chitinase,
biomass and pH were the responses used in different models to evaluate individually
fit ones. Quadratic model
was found to be fit for chitinase response
whereas in the case of biomass and pH, linear model was found to be fit
without the effect of others. Chitinase production was optimized with respect
to other responses such as biomass and pH in multiresponse analysis of
response surface design by using desirability approach. In multiresponse analysis,
following medium formulation (g/l), chitin, 15; urea, 0.32; CaCl2, 0.10
and MgSO4.7H2O, 0.08 was found to predict optimum chitinase
production of 482.77 units/ml with overall highest desirability of 0.854 as compared
to other formulation s. The selection of model was done on the basis of hi gh Adjusted
R-squared value and lowered p-value for each model in individual analysis
of
each response. In multiresponse experiment,
it was found that for response chitinase quadratic model and for responses pH
and biomass linear models were well fit. Through desirability analysis, it was found
that in the chitinase production, pH was essential as compared to biomass
in P. dispersa. Endochitinase and chitobiase actvities were also studied