5,912 research outputs found
Minimal inhibitory concentrations of sulbactam/ampicillin against drug sensitive and drug resistant isolates of Mycobacterium tuberculosis
A total of 92 isolates of Mycobacteriurn tuberculosis consisting of equal numbers of
sensitive and resistant strains was tested for their susceptibility to sulbactam and
ampicillin (in the ratio of 1:2) on Lowenstein-Jensen (LJ) and 7H11 agar media. The
geometric mean MIC was 63.97 μg/ml for the drug sensitive strains and 65.92 μg/ml
for the resistant strains, and the overall mean was 65.01 μg/ml. The high MIC on LJ
medium could be attributed to the higher protein content which resulted in greater
binding of sulbactam/ampicillin. On the other hand, the geometric mean MIC on
7H11 medium was 26.73 μg/ml for sensitive strains and 23.82 μg/ml for resistant
strains; the overall mean being 25.23 μg/ml. Although these MlCs of sulbactamampicillin
are higher than those reported earlier, they can be easily achieved in
serum. Further studies on experimental tuberculosis and in humans will be needed
to prove the efficacy of sulbactam/ampicillin in the treatment of patients with
multidrug resistant tuberculosis
Evaluation of the BACTEC radiometric method in the early diagnosis of tuberculosis
A comparison of the BACTEC radiometric method with the conventional culture and drug
susceptibility testing methods on isolates from clinical specimens in pulmonary and extrapulmonary
tuberculosis, childhood TB and TB in HIV-infected individuals was undertaken. In the case of
pulmonary TB, the rate of isolation of positive cultures was significantly faster with the BACTEC
method, with 87 per cent of the positives being obtained by 7 days, and 96 per cent by 14 days.
However, while there was no difference in the total number of positive cultures by the two methods
in smear positive pulmonary tuberculosis, in smear negative pulmonary TB, the BACTEC method
yielded more number of positive cultures. In extrapulmonary TB, HIV-TB and childhood TB,
although the BACTEC method did not yield additional positives, the detection of positives was
considerably faster than by the conventional methods, in which the degree of growth was also scanty.
The agreement in drug susceptibility tests was 94 per cent for streptomycin and isoniazid, 99 per cent
for rifampicin and 91 per cent for ethambutol. Further, most of the drug susceptibility test results
became available within 8 days by the BACTEC method. By facilitating early diagnosis, the BACTEC
method may prove to be cost effective in a population with a high prevalence of tuberculosis,
particularly in the extrapulmonary and paucibacillary forms of the disease
Domino tilings and the six-vertex model at its free fermion point
At the free-fermion point, the six-vertex model with domain wall boundary
conditions (DWBC) can be related to the Aztec diamond, a domino tiling problem.
We study the mapping on the level of complete statistics for general domains
and boundary conditions. This is obtained by associating to both models a set
of non-intersecting lines in the Lindstroem-Gessel-Viennot (LGV) scheme. One of
the consequence for DWBC is that the boundaries of the ordered phases are
described by the Airy process in the thermodynamic limit.Comment: 14 pages, 8 figure
Immune response & modulation of immune response induced in the guineapigs by Mycobacterium avium complex (MAC) & M. fortuitum complex isolates from different sources in the south Indian BCG trial area
A total of 139 guineapigs were used to study the immune response and its modulation induced by
Mycobacterium avium complex (MAC) and M. fortuitum complex strains obtained from different
sources in the south Indian BCG trial area. The guineapigs were divided into groups and some were
directly sensitised/immunised with different MAC strains, M. fortuitum complex strain or BCG and
others were sensitised with MAC or M. fortuitum complex and then immunised with BCG. The
resulting delayed type hypersensitivity (DTH) response in the different groups of guineapigs was
studied by skin tests using PPD-RT23 and PPD-B, and protective response was studied by challenging
the guineapigs with a south Indian low virulent strain of M. tuberculosis and enumerating the
bacilli in spleen at different points of time. The 3 strains of MAC induced similar low levels of DTH
to PPD-RT23 but much higher and varying levels of DTH to PPD-B. MAC strains from soil and
sputum induced different levels of immune modulation during subsequent immunisation with BCG
on the DTH response to PPD-RT23 and PPD-B. At 2 wk after challenge, 23.8, 81 and 90.5 per cent
protection was induced by the standard strain, soil isolate and sputum isolate of MAC, respectively,
while 33.3 per cent protection was induced by the M. fortuitum complex strain compared to the
protection induced by BCG alone. Prior exposure to MAC or M. fortuitum complex did not have
any modulatory effect on the protective immunity due to BCG at this time point. However, at 6
wk after challenge, while the guineapigs immunised with BCG were protected, modulation of the
protective response resulting from BCG was observed in the guineapigs sensitised with MAC and
M. fortuitum from soil
Evaluation of Procedures for Isolation of Nontuberculous Mycobacteria from Soil and Water
Six methods of decontamination each for the isolation of mycobacteria from soil and water were compared.
On the basis of the results obtained. three of the six methods for soil and two of the six methods for water were
further evaluated. For both soil and water samples, the method using 3% sodium lauryl sulfate in combination
with 1% NaOH yielded more positives than the other methods
Optimal Quantum Cloning via Stimulated Emission
We show that optimal universal quantum cloning can be realized via stimulated
emission. Universality of the cloning procedure is achieved by choosing systems
that have appropriate symmetries. We first discuss a scheme based on stimulated
emission in certain three-level-systems, e.g. atoms in a cavity. Then we
present a way of realizing optimal universal cloning based on stimulated
parametric down-conversion. This scheme also implements the optimal universal
NOT operation.Comment: 4 pages, 3 figure
Early bactericidal action of pulsed exposure to rifampicin, ethambutol, isoniazid & pyrazinamide in pulmonary tuberculosis patients
The bactericidal action of two therapeutic regimens on Mycobacterium tuberculosis was assessed by
viable counts in serial sputum samples in 49 pulmonary tuberculosis patients being treated with
rifampicin (R), etbambutol (Emb), isoniazid (I) and pyrazinamide (Z) together in a single dose thrice
weekly (REmbIZ3) or with REmb and IZ on alternate days (REmb3IZ3alt). In both groups of patients,
there was a significant reduction (P < 0.02) in the colony forming units (cfu) of M. tuberculosis per
ml of sputum during the first two days of treatment itself. This early bactericidal action (EBA) as well
as the reduction in counts during the subsequent days of treatment were similar (P > 0.2) for both
REmbIZ3 and REmb3IZ3alt regimens indicating that splitting up REmbIZ into REmb on one day and
IZ on the next day in short course chemotherapy (SCC) regimens may not affect the bactericidal action
of the regimens
The Anderson Model out of equilibrium: Time dependent perturbations
The influence of high-frequency fields on quantum transport through a quantum
dot is studied in the low-temperature regime. We generalize the non crossing
approximation for the infinite-U Anderson model to the time-dependent case. The
dc spectral density shows asymmetric Kondo side peaks due to photon-assisted
resonant tunneling. As a consequence we predict an electron-photon pump at zero
bias which is purely based on the Kondo effect. In contrast to the resonant
level model and the time-independent case we observe asymmetric peak amplitudes
in the Coulomb oscillations and the differential conductance versus bias
voltage shows resonant side peaks with a width much smaller than the tunneling
rate. All the effects might be used to clarify the question whether quantum
dots indeed show the Kondo effect.Comment: 13 pages, REVTEX 3.0, 5 figure
Consistency, Amplitudes and Probabilities in Quantum Theory
Quantum theory is formulated as the only consistent way to manipulate
probability amplitudes. The crucial ingredient is a consistency constraint: if
there are two different ways to compute an amplitude the two answers must
agree. This constraint is expressed in the form of functional equations the
solution of which leads to the usual sum and product rules for amplitudes. A
consequence is that the Schrodinger equation must be linear: non-linear
variants of quantum mechanics are inconsistent. The physical interpretation of
the theory is given in terms of a single natural rule. This rule, which does
not itself involve probabilities, is used to obtain a proof of Born's
statistical postulate. Thus, consistency leads to indeterminism.
PACS: 03.65.Bz, 03.65.Ca.Comment: 23 pages, 3 figures (old version did not include the figures
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