758 research outputs found
Effect of partial pancreatectomy on diabetic status in BALB/c mice.
Pancreatic regeneration after pancreatectomy has been well documented in animal models. However, the phenomenon of pancreatic regeneration in diabetes has not been exploited as yet. We report here the restoration of euglycaemic status in streptozotocin (STZ)-induced diabetic BALB/c mice, after 50% pancreatectomy. We observed that, after pancreatectomy, STZ-diabetic mice showed a rapid improvement in glycaemic status, starting from the 8th postoperative day, and remained normoglycaemic throughout a 90-day follow-up study. STZ-induced diabetic and control non-diabetic BALB/c mice underwent pancreatectomy and were monitored regularly for changes in body weight, plasma glucose and serum insulin concentrations and histological status of the pancreas. All the pancreatectomised animals showed euglycaemic status from about 20 days after operation, whereas a majority (around 70%) of the diabetic, sham-operated animals died of sustained hyperglycaemia by 20-30 days after operation. Examination of the regenerating pancreas indicated nesidioblastotic activity and supported the theory of a ductal origin of islet stem cells. Islets isolated from the regenerating pancreas showed a progressive increase in islet area (1227.9+/-173.2 micrometer(2) on day 5 compared with 2473.8+/-242.0 micrometer(2) by day 20). The increment in insulin concentrations and subsequent decrement in glycaemia of the diabetic pancreatectomised animals indicate islet neogenesis occurring after the operative insult, leading to a normoglycaemic status, probably recapitulating ontogeny. We have shown that induction of a regenerative stimulus (pancreatectomy) in conditions of STZ-induced diabetes may trigger pancreatic regenerative processes, thereby restoring a functional pancreas, in STZ-diabetic mice
Intermediate phase of the one dimensional half-filled Hubbard-Holstein model
We present a detailed numerical study of the Hubbard-Holstein model in one
dimension at half filling, including full finite-frequency quantum phonons. At
half filling, the effects of the electron-phonon and electron-electron
interactions compete, with the Holstein phonon coupling acting as an effective
negative Hubbard onsite interaction U that promotes on-site electron pairs and
a Peierls charge-density wave state. Most previous work on this model has
assumed that only Peierls or U>0 Mott insulator phases are possible at half
filling. However, there has been speculation that a third metallic phase exists
between the Peierls and Mott phases. We present results confirming the
intermediate metallic phase, and show that the Luttinger liquid correlation
exponent K_rho>1 in this region, indicating dominant superconducting pair
correlations. We explore the full phase diagram as a function of onsite Hubbard
U, phonon coupling constant, and phonon frequency.Comment: 4 pages, 4 EPS figures. v2: typos corrected. To appear in Phys. Rev.
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A Self Consistent Field Formulation of Excited State Mean Field Theory
We show that, as in Hartree Fock theory, the orbitals for excited state mean
field theory can be optimized via a self-consistent one-electron equation in
which electron-electron repulsion is accounted for through mean field
operators. In addition to showing that this excited state ansatz is
sufficiently close to a mean field product state to admit a one-electron
formulation, this approach brings the orbital optimization speed to within
roughly a factor of two of ground state mean field theory. The approach
parallels Hartree Fock theory in multiple ways, including the presence of a
commutator condition, a one-electron mean-field working equation, and
acceleration via direct inversion in the iterative subspace. When combined with
a configuration interaction singles Davidson solver for the excitation
coefficients, the self consistent field formulation dramatically reduces the
cost of the theory compared to previous approaches based on quasi-Newton
descent.Comment: 6 pages, 3 tables, 1 figure, plus supplementary materia
Antimicrobial and cytotoxic activity of Streptomyces sp. from Lonar Lake
Antibacterial substances from actinomycetes were isolated from marine environment of Lonar Lake and characterized. Out of the 24 isolates subjected to secondary screening, 12 isolates were active againstBacillus subtilis, 13 against Staphylococcus aureus, 7 against Escherichia coli, 3 against Proteus vulgaris and 4 against Salmonella typhi. Metabolites in the extract of broth of 48 hrgrown Streptomyces spp. culture no.2 proved to have antimicrobial and cytotoxic against human lung carcinoma cell A549
OPTIMIZATION OF FORMULATION OF SOLID DISPERSION OF FUROSEMIDE BY FACTORIAL DESIGN
Objective: The present study aimed to improve the rate of dissolution of furosemide by solid dispersion technique.
Methods: Solid dispersion of furosemide was prepared by using hydrogel isolated from the seeds of Lepidium sativum as a novel carrier by the solvent evaporation method. Solid dispersion was evaluated to study the improvement in the rate of dissolution. Molecular dispersion of furosemide in the novel carrier was studied by DSC and FTIR studies. Solid dispersion was filled in capsules after stability studies and the formulation was optimized by adopting factorial design.
Results: Solid dispersion of furosemide exhibited dissolution improvement from 13.54 % (plain furosemide) to 69.12% (solid dispersion) in the first 60 min. Improvement in dissolution efficiency was found to be retained after stability studies. Capsules were filled with the formulation of solid dispersion using two different grades of lactose-α lactose monohydrate and anhydrous lactose and were found stable after stabilization studies.
Conclusion: The dissolution improvement of furosemide was attributed to its molecular dispersion in the novel carrier selected for this study. The recrystallization of furosemide was prevented due to intermolecular interaction between the novel carrier and furosemide. This was confirmed by FTIR. Evaluation of the dissolution data of factorial batches was analyzed by ANOVA. Analysis of the data revealed that selected levels of α lactose monohydrate and anhydrous lactose would be useful to navigate design space
STUDY OF THE FUNCTIONALITY OF A NOVEL SOLUTION BINDER OBTAINED FROM OCIMUM BASILICUM SEEDS: A MECHANISTIC APPROACH
Objective: The aim of the present study was to investigate the functionality of the hydrogel isolated from the seeds of Ocimum basilicum (Gel) as a novel solution binder.
Methods: Paracetamol is known to possess poor manufacturability. Therefore it was selected as a model drug to study the efficiency of Gel as a solution binder. Paracetamol tablets were prepared at gradually increasing compression pressure from the granules prepared by using Gel of various viscosities as a solution binder. Compactibility parameter was calculated to assess the utility of Gel as a novel tablet binder. Optimization of the formulation was done by adopting factorial design as an appropriate DOE. Tablets of factorial batches were evaluated for disintegration time and crushing strength. The effect of viscosity of binder solution used to prepare granulation and compression pressure applied on granulation on the performance of the tablets was confirmed by analyzing the data using ANOVA.
Results: The addition of binder solution to prepare granulation with the viscosity ≥ 19.33 centipoises was found to be suitable to attain desired degree of agglomeration. The crushing strength of the tablets was found to be increased with an increase in compression pressure and an increase in viscosity of binder solution.
Conclusion: The compatibility parameter was observed to be increased as the viscosity of the binder solution added in the formulation was gradually increased. The Gel as a binder material was found to deform plastically at compression pressures 34.48 to 75.85 MPa. This confirmed its functionality as a solution binder in Paracetamol tablet preparation
Temperature-driven transition from the Wigner Crystal to the Bond-Charge-Density Wave in the Quasi-One-Dimensional Quarter-Filled band
It is known that within the interacting electron model Hamiltonian for the
one-dimensional 1/4-filled band, the singlet ground state is a Wigner crystal
only if the nearest neighbor electron-electron repulsion is larger than a
critical value. We show that this critical nearest neighbor Coulomb interaction
is different for each spin subspace, with the critical value decreasing with
increasing spin. As a consequence, with the lowering of temperature, there can
occur a transition from a Wigner crystal charge-ordered state to a spin-Peierls
state that is a Bond-Charge-Density Wave with charge occupancies different from
the Wigner crystal. This transition is possible because spin excitations from
the spin-Peierls state in the 1/4-filled band are necessarily accompanied by
changes in site charge densities. We apply our theory to the 1/4-filled band
quasi-one-dimensional organic charge-transfer solids in general and to 2:1
tetramethyltetrathiafulvalene (TMTTF) and tetramethyltetraselenafulvalene
(TMTSF) cationic salts in particular. We believe that many recent experiments
strongly indicate the Wigner crystal to Bond-Charge-Density Wave transition in
several members of the TMTTF family. We explain the occurrence of two different
antiferromagnetic phases but a single spin-Peierls state in the generic phase
diagram for the 2:1 cationic solids. The antiferromagnetic phases can have
either the Wigner crystal or the Bond-Charge-Spin-Density Wave charge
occupancies. The spin-Peierls state is always a Bond-Charge-Density Wave.Comment: 12 pages, 8 EPS figures. Longer version of previous manuscript.
Contains new numerical data as well as greatly expanded discussio
Temperature-driven transition from the Wigner crystal to the bond-charge-density wave in the quasi-one-dimensional quarter-filled band
It is known that within the interacting electron model Hamiltonian for the one-dimensional 1/4-filled band, the singlet ground state is a Wigner crystal only if the nearest-neighbor electron-electron repulsion is larger than a critical value. We show that this critical nearest-neighbor Coulomb interaction is different for each spin subspace, with the critical value decreasing with increasing spin. As a consequence, with the lowering of temperature, there can occur a transition from a Wigner crystal charge-ordered state to a spin-Peierls state that is a bond-charge-density wave with charge occupancies different from the Wigner crystal. This transition is possible because spin excitations from the spin-Peierls state in the 1/4-filled band are necessarily accompanied by changes in site charge densities. We apply our theory to the 1/4-filled band quasi-one-dimensional organic charge-transfer solids, in general, and to 2:1 tetramethyltetrathiafulvalene (TMTTF) and tetramethyltetraselenafulvalene cationic salts, in particular. We believe that many recent experiments strongly indicate the Wigner crystal to bond-charge-density Wave transition in several members of the TMTTF family. We explain the occurrence of two different antiferromagnetic phases but a single spin-Peierls state in the generic phase diagram for the 2:1 cationic solids. The antiferromagnetic phases can have either the Wigner crystal or the bond-charge-spin-density wave charge occupancies. The spin-Peierls state is always a bond-charge-density wave
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