DSpace community: 光電生物醫學研究中心

Skin Denervation, Neuropathology, and Neuropathic Pain in a Laser-Induced Focal Neuropathy

title: Skin Denervation, Neuropathology, and Neuropathic Pain in a Laser-Induced Focal Neuropathy abstract: Small-diameter sensory nerves innervating the skin are responsive to noxious stimuli, and an injury to these nerves is presumably related to neuropathic pain. Injury-induced neuropathic pain in animals can be produced by laser irradiation, which usually requires concomitant use of photosensitive dyes, known as the photochemical approach. It is not clear whether laser irradiation alone can induce neuropathic pain. In addition, two issues are important to apply these approaches: the relationship between the extent of laser irradiation and the occurrence of neuropathic pain, and the susceptibility of small-diameter sensory nerves in the skin to laser-induced neuropathic pain. To address these issues, we designed a new model of focal neuropathy by applying a diode laser of 532 nm (100 mW) to the sciatic nerve and evaluated small-diameter nerves by quantifying skin innervation and large-diameter nerves by measuring amplitudes of the compound muscle action potential (CMAP). Immediately after laser irradiation, epineurial vessels were occluded due to the formation of thrombi, and the blood flow through these vessels was markedly reduced. On postoperative day (POD) 2, animals developed characteristic manifestations of neuropathic pain, including spontaneous pain behaviors, thermal hyperalgesia, and mechanical allodynia. These phenomena peaked during PODs 7–21, and lasted for 3–6 weeks. The neuropathology at the irradiated site of the sciatic nerve included a focal area of axonal degeneration surrounded by demyelination and endoneurial edema. The extent of damage to large-diameter motor and sensory nerves after laser irradiation was evaluated by nerve conduction studies. On the irradiated sides, amplitudes of the compound muscle action potentials and sensory nerve action potentials (SNAPs) were reduced to 65.0 % (P < 0.0001) and 42 .5% (P < 0.01) of those on the control sides, respectively. Motor innervation of the neuromuscular junctions (NMJs) on plantar muscles was examined by combined cholinesterase histochemistry and immunohistochemistry. The ratio of innervated NMJs on the operated sides decreased to 76.3% of that on the control side. Skin innervation in the territory of the irradiated sciatic nerves was evaluated by immunohistochemistry with neuronal markers. Among these markers, epidermal nerve densities for protein gene product( PGP) 9.5, calcitonin gene- related peptide (CGRP), and substance P (SP) were significantly lower on the irradiated sides than the control sides with a different degree of loss for each marker (42.1–53.1%, P < 0.05). Results suggest that laser- induced focal neuropathy provides a new system for studying neuropathic pain. With this approach, the extent of nerve injury can be quantified. Both small- diameter epidermal nerves and large-diameter sensory and motor nerves are susceptible to laser-induced injury of different degrees.

Direct Detection of Bacterial Pathogens in Brain Abscesses by Polymerase Chain Reaction Amplification and Sequencing of Partial 16S Ribosomal Deoxyribonucleic Acid Fragments

title: Direct Detection of Bacterial Pathogens in Brain Abscesses by Polymerase Chain Reaction Amplification and Sequencing of Partial 16S Ribosomal Deoxyribonucleic Acid Fragments abstract: Objective: To evaluate the feasibility of detecting bacterial pathogens directly from the clinical brain abscess specimens by polymerase chain reaction (PCR) amplification and sequencing of baterial 16S ribosomal deoxyribonucleic acid (rDNA). Methods: A total of 14 specimens were tested by both culture and PCR amplification, targeting the full-length or a partial region of 16S rDNA. 16S rDNA is known to be conserved in bacteria. Sequencing of partial-length and full -length 16S rDNA was made. The sequence data were compared to known sequences of 16S rDNA in the National Center for Biotechnology Information GenBank by using the Basic Local Alignment Search Tool (BLAST) algorithm. The species with the best match of similarity were regarded as the pathogenic species in the samples. We also developed a Streptococcus- specific multiplex PCR analysis for identifying members of the Streptococcus species, the most common pathogen of brain abscesses. abscesses. Conclusion: Bacterial 16S rDNA sequences provide reliable clues to the identification of unknown pathogens. PCR analysis of 16S rDNA and sequencing may identify pathogens to the species level directly from brain abscesses. This approach is rapid and is useful especially in the identification of slow-growing and fastidious organisms.

Photodynamic Therapy of Oral Dysplasia with Topical 5-Aminolevulinic Acid and Light-Emitting Diode Array

title: Photodynamic Therapy of Oral Dysplasia with Topical 5-Aminolevulinic Acid and Light-Emitting Diode Array abstract: Background and Objectives: In Taiwan, more than two million people have the betel quid (BQ) chewing habit which is a risk factor related to premalignant lesion and squamous cell carcinoma of oral cavity. We developed a light-emitting diode (LED) array combined with topical 5- aminolevulinic acid (ALA) for photodynamic therapy (PDT) and evaluated its effectiveness for the treatment of oral lesions. Study Design/Materials and Methods: We compared the ALA-PDT effect of the homemadeLEDarray to that of a commercial light source on cultured Ca9-22 human gingival carcinoma cells and the DMBA-induced hamster buccal pouch carcinoma model. Furthermore, we treated several patients having an oral lesion using a topical ALA delivery system and the LED array . Results: TheLEDarray light source was as effective as the commercial light source for ALA-PDT in cultured Ca9-22 cells with LD50 of 4.5 and 4.3 J/cm2, respectively, using an MTT assay. This light source was also effective in the DMBA- induced hamster buccal pouch carcinoma model, and in the patients of oral leukoplakia. Conclusions: ALA-PDT is effective for premalignant lesions such as mucosal dysplasia and carcinoma in situ of oral cavity. Good results could be obtained by using the homemade LED array as light source. The LED array has the advantages of low cost, high reliability, and portability. It is safe, convenient and easy to use for the treatment of oral dysplasia. Lasers Surg . Med. 34:18–24, 2004.

Delta-Aminolaevulinic Acid Mediated Photodynamic Antimicrobial Chemotherapy on Pseudomonas Aeruginosa Planktonic and Biofilm Cultures

title: Delta-Aminolaevulinic Acid Mediated Photodynamic Antimicrobial Chemotherapy on Pseudomonas Aeruginosa Planktonic and Biofilm Cultures abstract: To demonstrate photodynamic antimicrobial chemotherapy (PACT ) against planktonic and biofilm cultures of Pseudomonas aeruginosa, using photoporphyrin IX which could be endogenously synthesized by administrating delta- aminolaevulinic acid (delta-ALA), and a light emitted diode( LED) array to photoactivate the photosensitizer. P. aeruginosa suspended cells or biofilms, grown on a rotating disk reactor, were treated by different concentrations of delta-ALA in the dark for 1 h, followed by LED irradiation for various time. Regrowth experiments were conducted by placed PACT-treated disks back to a sterile reactor. Viable cells were determined by serial dilution and plate counts. Both P. aeruginosa planktonic and biofilm cells were inhibited by PACT with light doses or photosensitizer concentrations increasing. Treatments of planktonic cells with 10 mM delta-ALA and incident dose 240 J cm(-2) or 7. 5 mM ALA and incident dose 360 J cm(-2) led to completely photoinactivation. No viable biofilm cells were found after treatment of 20 mM delta-ALA and incident dose 240 J cm(-2). However, regrowth was observed once PACT-treated biofilms were put back to a sterile reactor. Regrowth could be prevented only if biofilm samples were treated PACT twice. delta-ALA-mediated PACT on P. aeruginosa planktonic and biofilm cells was effective, though the detailed mechanism still required further investigation. (C) 2004 Elsevier B.V. All rights reserved.