Laser tomography of heterogeneous scattering media using spatial and temporal resolution

Time-resolved tomography is performed in transillumination by using 527 nm picosecond pulses from a passively mode-locked doubled Nd/glass laser and a streak camera to select photons according to their flight time. This work reports on the increase in contrast of a time-resolved profile of a 2 mm radius opaque object embedded in a scattering medium, constituted of diluted milk in a 30 mm thick cell. For spatial analysis, the emerging photons are detected through a 6 mm slit at the outlet face of the cell. Transmission profiles obtained as a function of time show that the contrast is enhanced for the shortest flight times, while the ‘shadow’ of the object is no longer detected after about 100 ps. Moreover, improvements in contrast are studied for different configurations of the model, to analyse separately the role of collimated and scattered photons. It is expected that such a tomographic method based on time-resolved absorption could be applied to imaging for more complex biological structures in the red and near-infra-red range.     

Transoral laser resection of hypopharyngeal liposarcoma

Liposarcomas are rare malignant tumours of the connective tissue. Microscopically they resemble lipomas. They are usually found on the limbs or trunk. Fewer than 40 cases of hypopharyngeal liposarcoma have been reported in the literature. Surgical excision with a cervical or endoscopic approach has been the first-line treatment for these cases. We present a patient with the first documented primary excision via carbon dioxide laser using an entirely transoral approach. This case suggests a new standard of management but also highlights the difficulties with investigation and diagnosis in a rare presentation.     

应用激光电泳技术对MA737小鼠乳腺癌细胞膜表面电荷特性的研究

本工作应用激光多普勒电泳技术对ＭＡ７３７小鼠乳腺癌细胞膜表面电荷特性及高温（４２．５℃）对癌细胞的热效应进行了深入的研究。结果发现，ＭＡ７３７癌细胞的电泳迁移率（ＥＰＭ）明显高于相应正常细胞的ＥＰＭ（约２０％），表明癌细胞表面负电荷增高；实验发现唾液酸可能是ＭＡ７３７癌细胞膜表主要负电基团的来源之一。研究还发现，ＭＡ７３７癌细胞的热敏性比相应的正常细胞强，随高温受热时间的延长，癌细胞的ＥＰＭ呈下降趋势。     

Prevention of hypotony after trabeculectomies with mitomycine

Hypotony with reduced a reduced visual acuity is often seen after trabeculectomy with mitomycine. In this study we describe measures such as reattaching the sleral flap with at least seven nylon sutures and the controlled and delayed use of argon laser suture lysis. With these preventative measures the percentage of hypotonies (IOP 6 mmHg) three months after surgery was reduced from 38 to 15% and chronically reduced visual acuity was reduced from 38 to 5%. With these adaptations in the surgical technique the complication rate of trabeculectomies with mitomycine can be markedly reduced without affecting the mean IOP (10.9 mmHg versus 10.8 mmHg) three months after surgery and the percentage of eyes with IOP 18 mmHg or less without medication (94 versus 91%).     

鼾症手术的探讨

目的 探讨鼾症的常规的悬雍垂腭咽成形术（Ｕｖｕｌｐａｌａ ｔｏｐｈａｒｙｎｇｏｐｌａｓｔｙ ＵＰＰＰ）与激光悬雍垂腭咽成形术（Ｌａｓｅｒ Ｕｖｕｌｏｐａｌａｔｏｐｈａｒｙｎｇｏｐａｓｔｙ,ＬＵＰＰＰ）的优缺点。方法 ＵＰＰＰ加半导体激光或ＣＯ２及ＹＡＧ手术。结果 综合术式共治４０例,随访１年以上,总有效９５％,显效１８例（４５％）,好转２０例（５０％）无效２例（５％）。结论 传统ＵＰＰＰ和ＬＵＰＰ     

Initial treatment of the early stages (I, II) of supraglottic squamous cell carcinoma: partial laryngectomy versus radiotherapy

The purpose of this study was to define the treatment of choice (partial laryngectomy vs radiotherapy) in the early stage of supraglottic squamous cell cancer (ESSC). One hundred and fifteen patients with ESSC were treated with either partial laryngectomy (25 patients) or with radiotherapy(90 patients) between January 1984 and December 1996. All patients had a follow-up of over ¶29 months. Radiotherapy (RT) had a local control rate of 79%, which increased to 90% with salvage surgery, and a high larynx preservation rate (83%). Partial laryngectomy (PL) offered a better initial local control rate of 84%, which increased to 88% with salvage surgery, and functional results were also good (80%). No statistically significant differences were found between RT and PL. RT was less costly, showed better suitability for treatment, produced moderate morbidity and sequelae, and local recurrence was easier to rescue. However, it is a once-only application technique. PL showed higher immediate postoperative morbidity, higher cost and lower suitability for treatment but had fewer sequelae, offered the best initial local control and is multi-applicable. No clear oncological arguments were found in our series to define whether PL or RT is the treatment of choice for ESSC. Both are effective therapies. Secondary factors such as suitability for treatment, morbidity, cost and applicability should be individually evaluated when choosing the type of treatment. As the laser endoscopic approach decreases morbidity and costs and makes the condition more suitable for treatment, it could be the treatment of choice for ESSC, in cases where local tumoral extent and larynx exposure allow radical excision.     

磷酸钛钾激光声带切除术不同术式的临床特点

目的　探讨支撑喉镜下磷酸钛钾 (potasiumtitaniumphosphate,KTP)激光声带切除术不同术式的选择及愈合过程中的临床特点。方法　选择 76例早期声门型喉癌行KTP激光声带切除术 ,对不同术式术后喉内结构恢复过程、音质变化等进行随访观察记录。结果　Ⅰ型术式 11例 ,3个月后恢复喉的正常结构及功能 ;Ⅱ型术式 5 0例 ,3个月后有声带样粘膜皱襞 (以下称新声带 )形成 ,基本恢复喉的结构 ;Ⅲ型术式 15例 ,6个月后多数形成粘膜隆起 ,但失去运动功能。复发时间集中在术后 2～ 4个月 ,复发率为 6 .7% ,2年及 5年生存率为 10 0 %。结论　KTP激光声带切除术疗效好 ,损伤小。Ⅱ型和Ⅲ型术式在保证根治癌肿的基础上应尽可能保留声带肌。     

YAG激光治疗牙本质过敏症的疗效分析

目的 :为探索治疗牙本质过敏症的新疗法 ,观察激光治疗后过敏齿的临床疗效 .方法 :应用 Nd:YAG激光点射治疗过敏齿 152 1颗 ,其中 °过敏 10 17颗 , °过敏 50 4颗 .结果 :即刻有效率为98.6 8% ;经 3～ 12个月的临床观察 , °过敏痊愈 814颗 (80 .0 4 % ) ,显效 183颗 (17.99% ) ,有效率为98.0 3% ; °过敏痊愈 119颗 (2 3.6 1% ) ,显效 339颗 (6 7.2 6 % ) .结论 :两组总有效率为 95.6 6 %。操作简便 ,无痛苦 ,是一种快速有效的方法     

A comparative study of etching enamel by acid and laser

Acid etching is regarded as one of the main means of providing additional retention in aesthetic dentistry. Alternative methods of achieving bonding to tooth tissue which have been proposed include laser etching. Conflicting results on bond strength to enamel have been reported for laser etching. Here the tensile bond strength of composite resin to acid- and laser-etched enamel was measured and the topographical differences between the surfaces were evaluated using the scanning electron microscope. The laser used was a pulsed Nd-YAG laser at 10 pulses per second with a pulse length of 150s, 80mJ pulse^–1, 1.064m wavelength. The results obtained indicate that the bond strength of laser-etched enamel was significantly lower than that of acid-etched enamel. In this study the difference may be attributable to the chromophore used. Variations in the rate of traverse of the laser tip across the surface did not appear to produce significant alterations in the bond strength.     

The relevance of pulse repetition rate and radiant exposure to the neurophysiological effects of low-intensity laser (820 nm/pulsed wave) irradiation upon skin temperature and antidromic conduction latencies in the human median nerve

The effects of low-intensity near-infra-red laser irradiation (820 nm; 1.5 and 9.0 J cm^–2; pulsed at 12 Hz, 73 Hz and 5 kHz) upon peripheral neurophysiology and skin temperature were investigated using antidromic conduction studies in the human median nerve in vivo. Healthy human volunteers (n = 90) were recruited and allocated randomly to either a control group (n=10) or one of eight experimental groups (two radiant exposures, 1.5 J cm^–2 and 9.0 J cm^–2 at one of three pulse repetition rates, 12 Hz, 73 Hz or 5 kHz, in addition to a placebo group for each radiant exposure;n = 10 all groups). Analysis of variance (ANOVA) demonstrated a significant (p0.05) decrease in skin temperature following irradiation at the lowest radiant exposure (1.5 J cm^–2) combined with pulse repetition rates of 73 Hz and 5 kHz, with the greatest effect at 73 Hz. These changes in skin temperature were coupled with increases in negative peak latency (NPL); ie changes in NPL were inversely related to changes in skin temperature. However, in contrast to the authors' previous findings using continuous wave (CW) laser irradiation, differences in NPL were not found to be significant. These findings, therefore, provide little evidence of the neuro-physiological effects of low-intensity infra-red irradiation at the dosage levels and pulse repetition rates used here.