We directly measured curvature elasticity of dipalmitoylphosphatidylcholine multilamellar bilayers close to the chain-melting transition using the method of electric-field-induced bending deformation ...of the cylindrical tubes. The result shows that the bending modulus,
κ
c, decreases remarkably at temperatures close to the melting transition temperature. This reflects a softening of the bilayer resulted from the area fluctuations as predicted theoretically. However, the decrease of
κ
c near the transition is far smaller than that predicted. This is due to the experimental method and the narrow transition width of the multilamellar bilayers. Nevertheless, the result obtained gives direct evidence of the
κ
c reduction predicted for multilamellar membranes in the transition regime. Below about 41°C, almost of all cylindrical tubes cannot response to the electric field, indicating a very large bending rigidity.
The effects of griseolic acid (GA), a cyclic-AMP phosphodiesterase (PDE) inhibitor, and its 8′-pivaloyloxymethyl (POM) ester on intraocular pressure (IOP) in rabbits were investigated. When 50 μ1 of ...1 and 2% GA POM ester solutions were topically applied to one eye in normal rabbits, significant IOP decreases were detected at 2 hrs and at 1 to 5 hrs, respectively. Other than ocular hypotension, no other ocular effects were detected locally even after administration of 2% GA POM ester. A more marked reduction in IOP occurred after the intravitreal injection of the GA POM ester. IOP was also reduced when GA was used in an intravitreal injection but not when it was topically applied. The difference in permeability between GA and GA POM ester across the corneal epithelium may explain why GA failed to reduce IOP following topical administration. GA and the GA POM ester inhibited cAMP PDE in rabbit ciliary body at low concentrations, the I50 being 0.075μM and 2.4μM, respectively, with 0.25pM cAMP as substrate. GA and the GA POM ester markedly increased cAMP levels in vitro in iris-ciliary body specimens. Possibly, GA POM ester or its analogues may represent a new mechanistic class of ocular hypotensive agents.
Using the second-order Coulomb-corrected Volkov function as a continuum state, we derive quantum mechanically analytical formulas for the photoionization rate of hydrogen atoms irradiated by a ...linearly polarized electric field in the tunneling regime. From the analytical formula is directly drawn the important conclusion that the role of the first-order Coulomb correction is to reduce the ionization potential. As a result, the photoionization rate is enhanced compared with that in the absence of the Coulomb correction. In addition, the second-order correction modifies the Keldysh parameter, decreases the binding energy, and increases the photoionization rates relative to those of the first-order Coulomb correction. We estimate the effects of the respective Coulomb corrections on the resonance structure of the photoionization rate, Keldysh parameter, and ponderomotive energy.
Orally administered Madopar (levodopa/benserazide 4:1) dose-dependently antagonized haloperidol-induced (1 mg/kg s.c.) catalepsy in MPP(+)-lesioned mice. Pretreatment with a new selective ...catechol-O-methyltransferase (COMT) inhibitor, tolcapone (30 mg/kg p.o.), slightly potentiated the antagonistic effect of Madopar (15 mg/kg p.o.) on haloperidol-induced catalepsy. The ability of tolcapone to increase the Madopar effect was significantly attenuated by high doses of 3-O-methyldopa (3-OMD) (800 mg/kg i.p.). This might suggest a competitive blockade of the active transport of levodopa through the blood-brain barrier. In conclusion, the inhibitory effect of tolcapone on the O-methylation of levodopa to 3-OMD by COMT is largely due to improved levodopa and dopamine availability in the brain, and to the reduced formation of 3-OMD.
The juxtaoral organ of Chievitz (JOOC) is a normal permanent anatomical structure located within the soft tissue overlying the angle of the mandible in the buccotemporal space. Although the sensory ...organ nature of JOOC, repeatedly mentioned in German publications, has been neglected in the last decade by the American anatomists and pathologists, we incidentally found JOOC‐type squamous epithelium accompanied by Pacinian corpuscles. This fortuitous finding appears to be the first report of the authentic Paciniform nerve endings within JOOC, supporting its mechanosensory function.
An ultrastructural analysis of oral balloon cell nevus of intramucosal type complemented with an immunohistochemical study was performed for the first time. The lesion was composed of large balloon ...cells with an admixture of small nevus cells and melanophages at the periphery. Balloon cells showed cytoplasmic accumulation of vacuoles of varying sizes and the presence of microgranular and vacuolated melanosomes were found. Residual cytoplasm contained no identifiable organelles. A spectrum of transitional forms between balloon cells and conventional nevus cells with microvacuoles was readily observed. Both cells exhibited intense immunoreactivity to multiple melanocytic markers. Ballooning phenomenon was not evident in melanophages containing a large amount of melanosome complex. It can be inferred, from the present and previous observations, that progressive vacuolization of melanosomes in nevomelanocytes may be responsible for the formation of peculiar ballooning appearance, suggesting an aberrant melanogenesis.
We recently reported that hypoxic-ischemic (HI) insult to the brain of 7-d-old rats resulted in a slowly progressive learning and memory disability, which started at around 5 wk after HI, a time ...frame that is representative of human adolescence. The purpose of the present study was to examine whether physical or mental exercises can prevent this late-onset, slowly progressing disability. Wistar rats were subjected to left carotid ligation followed by 2 h of hypoxic stress (8% O2 and 92% N(2) at 33 degrees C). Sham-control rats were subjected to the same procedure without ligation and hypoxic stress. Six weeks after the HI, the animals were divided into four groups: pretraining control, no training control, pretraining HI, and no training HI groups. We used the plus maze, eight-arm radial maze, and choice reaction time task as the rehabilitative training. Sixteen weeks after the HI, the water maze task was performed over 5 d to evaluate spatial learning ability; thereafter, cerebral morphology of the animals was examined. There were no differences in swimming length and latency between the pretraining control and no training control groups. Swimming length and latency in the pretraining HI group were significantly shorter and swifter than those in the no training HI group. The infarct areas on the left cerebral hemisphere were equivalent between pretraining HI and no training HI groups at each sectional slice. Rehabilitative training tasks prevented the neonatal HI-induced late-onset slowly progressive learning and memory disability.
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