C F Zhao | PubMed Health

PubMed2000

The A3 pulley.

The tendon-pulley geometry and gliding resistance with and without the A3 pulley were compared in 6 fresh human cadaver fingers. We measured the x-ray images of the distal A2 pulley-tendon angle and proximal A4 pulley-tendon angle with varying degrees of proximal interphalangeal joint flexion between 0 degrees and 120 degrees before and after A3 pulley resection. The gliding resistance of the flexor digitorum profundus tendon under the A2 pulley was also measured at varying tendon-pulley angles. With the A3 pulley removed, the tendon-pulley angle significantly increased compared with the A3 intact state. The gliding resistance between tendon and pulley quadratically increased as the tendon-pulley angle increase from 0 degrees to 60 degrees. These results indicate that the A3 pulley might serve to reduce tendon-pulley gliding resistance by reducing the tendon-pulley angle during finger flexion.

Biomechanical Phenomena↗

PubMed1997

Two-photon photodynamic therapy.

OBJECTIVE: We demonstrate the use of infrared excitation in conjunction with an efficient two-photon absorbing dye and a photosensitizer in photodynamic therapy. SUMMARY BACKGROUND DATA: An efficient two-photon absorbing dye is excited by short infrared (800 nm) laser pulses, which transfer its energy to the photosensitizer and the photosensitizer, in turn, generates the singlet oxygen. METHODS: A new approach to photodynamic cancer therapy based on the strong two-photon absorption of certain newly developed organic molecules. Near infrared pulsed laser light efficiently excites these molecules which, in turn, transfer the energy to the photosensitizer used in photodynamic therapy. RESULTS: A newly synthesized two-photon absorbing dye 4-[N-(2-hydroxyethyl)-N-(methyl) amino phenyl]-4'-(6-hydroxyhexyl sulfonyl)stilbene (APSS), which exhibits a strong two-photon absorption at 800 nm, and upconverted fluorescence at 520 nm, in solution in the presence of a photosensitizer was found to generate singlet oxygen under infrared excitation (800 nm). The generation of singlet oxygen in a reaction system containing two-photon absorbing dye and photosensitizer under infrared excitation has been chemically detected by using ADPA (9,10-anthracenedipropionic acid) as singlet oxygen detector. CONCLUSIONS: The efficient two-photon absorption of certain chromophores can be used to extend photodynamic therapy to the near infrared spectral region. Whereas the photosensitizer itself may not exhibit two-photon absorption, it could be used in conjunction with one of these new chromophores. The chromophores can act as "photon harvesters" whereby they absorb two photons of near infrared light and transfer the energy to the photosensitizer, which can generate singlet oxygen in the presence of atmospheric oxygen.

Absorption↗