Heparin is a natural proteoglycan that was first described in 1916. In addition to its well characterized effect on blood coagulation, it is becoming clear that heparin also modulates inflammatory processes on several levels, including the interference with leukocyte-endothelium interaction. Anecdotal observations suggest a better clinical outcome of heparin-treated patients with bacterial meningitis. The authors demonstrate that heparin, a glycosaminoglycan, inhibits significantly in the early phase of experimental pneumococcal meningitis the increase of 1) regional cerebral blood flow (125 +/- 18 versus 247 +/- 42%), 2) intracranial pressure (4.5 +/- 2.0 versus 12.1 +/- 2.2 mm Hg), 3) brain edema (brain water content: 78.23 +/- 0.33 versus 79.49 +/- 0.46%), and 4) influx of leukocytes (571 +/- 397 versus 2400 +/- 875 cells/microL) to the cerebrospinal fluid compared with untreated rats. To elucidate the possible mechanism of this observation, the authors investigated for the first time leukocyte rolling in an inflammatory model in brain venules by confocal laser scanning microscopy in vivo. Heparin significantly attenuates leukocyte rolling at 2, 3, and 4 hours (2.8 +/- 1.3 versus 7.9 +/- 3.2/100 microm/min), as well as leukocyte sticking at 4 hours (2.1 +/- 0.4 versus 3.5 +/- 1.0/100 microm/min) after meningitis induction compared with untreated animals. The authors conclude that heparin can modulate acute central nervous system inflammation and, in particular, leukocyte-endothelium interaction, a key process in the cascade of injury in bacterial meningitis. They propose to evaluate further the potential of heparin in central nervous system inflammation in basic and clinical studies.
Diazonium reactions
with carbon nanotubes form optical sp3 defects that can
be used in optical and electrical circuits. We
investigate a direct on-device reaction supported by confined laser
irradiation and present a technique where an arbitrary carbon nanotube
can be preferentially functionalized within a device by matching the
light frequency with its transition energy. An exemplary reaction
was carried out between (9,7) nanotube and 4-bromobenzenediazonium
tetrafluoroborate. The substrate supported nanotubes of multiple semiconducting
chiralities were locally exposed to laser light while monitoring the
reaction kinetics in situ via Raman spectroscopy.
The chiral selectivity of the reaction was confirmed by resonant Raman
spectroscopy, reporting a 10 meV E
22 transition
energy red-shift only of the targeted species. We further demonstrated
this method on a single tube (9,7) electroluminescent device and show
a 25 meV red-shifted emission of the ground state E
11 compared to the emission from the pristine tubes.
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