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- Bottom water
warming along
the pathway of
lower
circumpolar
deep water in
the Pacific
Ocean: Geophysical
Research
Letters, Vol.
33 (14
December
2006), L23613.
Source: Geophysical Research Letters, Vol. 33 (14 December 2006), L23613. - Structures and
spectral
signatures of
protonated
water networks
in
bacteriorhodop
sin.: Proc Natl Acad
Sci U S A,
Vol. 104, No.
17. (24 April
2007), pp.
6980-6985.Netw
orks of
internal water
molecules are
thought to
provide proton
transfer
pathways in
many enzymatic
and
photosynthetic
reactions.
Extremely
broad
absorption
continua
observed in
recent IR
spectroscopic
measurements
on the
photodriven
proton pump
bacteriorhodop
sin (BR)
suggest such
networks may
also serve as
proton storage
and release
sites for
these
reactions. By
combining
electronic
structure
calculations
with molecular
mechanical
force fields,
we examine the
dynamics and
the resulting
IR spectra of
two protonated
water
networks,
H+.(H2O)3 and
H+.(H2O)4, in
the release
pocket of the
initial state
of BR, which
possibly serve
as proton
donors to the
extracellular
surface. For
both network
sizes,
topologically
similar
structures are
found, which
are anchored
at residues
E194 and E204
and stabilized
by additional
hydrogen bonds
from
neighboring
protein side
chains. These
protonated
water networks
assume neither
the classic
Zundel nor
Eigen motives
but prefer
wire-like
topologies.
Upon gauging
calculated IR
spectra of
finite
clusters with
experimental
gas-phase
data, it is
possible to
link spectral
features
computed for
these
chain-like
structures in
the initial
state of the
BR photocycle
to the
measured
absorption
continua, in
particular for
the larger
H+.(H2O)4
network.
Furthermore,
the free
energy of
proton
dislocation
along these
chains is
found to be
within the
range that is
easily
accessible at
room
temperature
because of
fluctuations.
Source: Proc Natl Acad Sci U S A, Vol. 104, No. 17. (24 April 2007), pp. 6980-6985. - PG490-88, a
derivative of
triptolide,
causes tumor
regression and
sensitizes
tumors to
chemotherapy: Mol Cancer
Ther, Vol. 2,
No. 9. (1
September
2003), pp.
855-862.Treatm
ent of solid
tumors with
combinations
of
chemotherapeut
ic agents has
not led to
significant
increases in
long-term
survival.
Recent studies
support a role
for inhibitors
of checkpoint
arrest as a
means to
enhance the
cytotoxicity
of
chemotherapy.
We have shown
previously
that
triptolide
(PG490), an
oxygenated
diterpene
derived from a
Chinese
medicinal
plant, induces
apoptosis in
cultured tumor
cells and
sensitizes
tumor cells to
topoisomerase
inhibitors by
blocking
p53-mediated
induction of
p21. Here we
extend our
studies to a
tumor
xenograft
model and
evaluate the
efficacy and
safety of
PG490-88
(14-succinyl
triptolide
sodium salt),
a
water-soluble
prodrug of
PG490. We also
look at the
combination of
PG490 or
PG490-88 with
CPT-11, a
topoisomerase
I inhibitor,
in cultured
cells and in
the tumor
xenograft
model. We show
that PG490-88
is a safe and
potent
antitumor
agent when
used alone,
causing tumor
regression of
lung and colon
tumor
xenografts. We
also show that
PG490-88 acts
in synergy
with CPT-11 to
cause tumor
regression. A
phase I trial
of PG490-88
for solid
tumors began
recently and
safety and
optimal dosing
data should
accrue within
the next 12
months. Our
findings that
PG490-88
causes tumor
regression and
that it acts
in synergy
with
DNA-damaging
chemotherapeut
ic agents
suggest a role
as an
antineoplastic
agent and
chemosensitize
r for the
treatment of
patients with
solid tumors.
Source: Mol Cancer Ther, Vol. 2, No. 9. (1 September 2003), pp. 855-862. - A numerically
efficient and
stable
algorithm for
animating
water waves: The Visual
Computer, Vol.
18, No. 1.
(February
2002), pp.
41-53.Water
motion can be
realistically
captured by
physically
based fluid
models. We
begin by
presenting a
survey on
fluid
simulation
models that
are based on
fluid dynamics
equations,
from the most
comprehensive
Navier?Stokes
equations to
the simple
wave equation.
We then
present a
model that is
based on the
two-dimensiona
l shallow
water
equations. The
equations are
integrated by
a novel
numericalmetho
d ? the
implicit
semi-Lagrangia
n integration
scheme ? which
allows large
timesteps
while
maintaining
stability, and
which is
described in
detail in this
paper. Gentle
wave motions,
the
superposition
of waves,
drifting
objects, and
obstacles and
boundaries of
various shapes
can be
efficiently
simulated with
this model.
Source: The Visual Computer, Vol. 18, No. 1. (February 2002), pp. 41-53. - Glass
transition and
layering
effects in
confined
water: A
computer
simulation
study: The Journal of
Chemical
Physics, Vol.
113, No. 24.
(2000), pp.
11324-11335.Si
ngle particle
dynamics of
water confined
in a nanopore
is studied
through
computer
molecular
dynamics. The
pore is
modeled to
represent the
average
properties of
a pore of
Vycor glass.
Dynamics is
analyzed at
different
hydration
levels and
upon
supercooling.
At all
hydration
levels and all
temperatures
investigated a
layering
effect is
observed due
to the strong
hydrophilicity
of the
substrate. The
time density
correlators
show, already
at ambient
temperature,
strong
deviations
from the Debye
and the
stretched
exponential
behavior. Both
on decreasing
hydration
level and upon
supercooling
we find
features that
can be related
to the cage
effect typical
of a
supercooled
liquid
undergoing a
kinetic glass
transition.
Nonetheless
the behavior
predicted by
mode coupling
theory can be
observed only
by carrying
out a proper
shell analysis
of the density
correlators.
Water
molecules
within the
first two
layers from
the substrate
are in a
glassy state
already at
ambient
temperature
(bound water).
The remaining
subset of
molecules
(free water)
undergoes a
kinetic glass
transition;
the relaxation
of the density
correlators
agree with the
main
predictions of
the theory.
From our data
we can predict
the
temperature of
structural
arrest of free
water. ©2000
American
Institute of
Physics.
Source: The Journal of Chemical Physics, Vol. 113, No. 24. (2000), pp. 11324-11335.
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