Preserving the Integrity of Oesophageal Stents with Laser Therapy and Argon Plasma Coagulation: An In Vitro Study

. Thermal lasers and argon plasma coagulation are widely used in the treatment of stent overgrowth in patients with advanced oesophageal malignancy. The aim of treatment is to achieve patency while avoiding damage to the prosthesis. This experimental study was designed to determine the power and duration of application that can be safely tolerated by four different types of oesophageal prostheses. Five stents were studied: wall stent; open metal mesh stent (uncovered Ultraflex); covered metal mesh stent (covered Ultraflex); Gianturco (Z-stent); Esophagocoil. Nd-YAG Laser, GaAlAs diode laser and argon plasma coagulation were applied in non-contact mode at gradually increasing power levels and duration and the effects were observed. The use of argon plasma coagulation on Esophagocoil stent seems safe in power settings of 100 W up to 10 s. The diode laser is intermediate in that Gianturco and Esophagocoil stents can withstand pulses of up to 50 W for about 2 s. The Nd-YAG laser is detrimental to most stents at power levels of 20 W. Only the Esophagocoil withstands Nd-YAG pulses of 60 W but only up to 1 s. Wallstent, open and membrane-covered mesh stents perform poorly in that they can only tolerate up to 1.5 s of power at 25 W with the Diode and 1.0 s of power at 20 W with Nd-YAG laser. The use of different thermal modalities on the five stents has indicated safe power limits and duration. Membrane-covered stents are always damaged by thermal laser application unless the membrane is truly transparent. Paper received 23 February 2000; accepted after revision 24 March 2000.     

LED刺激器多焦视网膜电图一阶和二阶反应波形研究

目的研究二极管发光器(LED)的多焦视网膜电图(mfERG)的一阶及二阶波形特点。设计前瞻性、非对照干预研究。研究对象18例(18眼)正常人。方法18眼随机分为两组分别作阴极射线管(CRT)及LED的mfERG检查。LED刺激时间分为1/10(1．7ms)、3/10(5ms)、5/10(8．3ms)、7/10(11．7ms)、10/10(16．7ms)5种。主要指标mfERG总和反应波形特点,P1、N1及N2波形态、振幅密度及潜伏期。结果CRT及LED刺激器mfERG一阶反应波形基本相似；CRT及LED刺激器的mfERG二阶反应波形不同,前者的P1波呈尖峰状,后者的P1波较宽,呈方形,且伴有一个较深的N2波。随着刺激时间的延长,LED刺激器的mfERG一阶及二阶反应中的P1波及N1波的振幅密度增加,潜伏期延长。结论CRT及LED刺激器的mfERG一阶反应波形基本相同,但LED的二阶反应波形更丰富,其可能包涵了更多视网膜内层信息。(眼科,2006,15：351-355)     

Diode array detection of low level co-eluting species in high-performance liquid chromatography

A simple and sensitive method for detecting low levels (0.5 and 1.0%, w/w) of co-eluting species in HPLC has been developed. This method is based on the subtraction of normalized peak up-slope and down-slope spectra from that of the apex. Visual inspection of the resultant “difference spectra” allows for a qualitative judgement regarding the integrity of the peak under consideration.     

二极管阵列检测技术在中药化学分析中的应用

本文简要介绍了二极管阵列检测技术在中药化学分析中的几方面应用实例。峰纯度、色谱峰光谱一致性检测是高效液相色谱分析方法的可靠性和适用性评价的较先进的手段。     

Habituation of human limbic neuronal response to sensory stimulation

Hippocampal, parahippocampal gyrus, and amygdalar neuronal responses to visual and acoustic stimuli were analyzed during trains of several hundred stimulus repetitions as part of an investigation of sensory pathways to medial temporal lobe structures in complex-partial epilepsy patients who were being monitored with depth electrodes. Ten percent of more than 500 single and multiple units tested were responsive to simple sensory stimuli. The majority of the responsive units were recorded in the posterior parahippocampal gyrus (HG) during visual stimulation. Although neurons in pes hippocampi (PH; Ammons's horn) were also responsive to photic stimuli, no visually responsive units were found in amygdala. Very few units were responsive to acoustic stimuli, and these were found only in PH and amygdala, and not in HG. Significant trends of increase or decrease in response amplitude during trains of stimuli were found in all acoustically responsive units. Significant trends of visual response amplitude increase or decrease were found in 20% of PH units, and in 44% of HG units. Mean latencies of acoustically responsive units were longer than those of visually responsive units, and latencies of PH sensory units showing decremental response were longer than nondecremental PH units. Rate of response decrement was usually linear for acoustic responses and exponential for visual responses. The response dynamics of medial temporal lobe neurons are compared with those described in the animal limbic system and are related to habituation of human sensory evoked scalp potentials.     

A device for enhancing the visibility of the tip of a glass micropipette: Application in neuroanatomy

In neuroanatomical tract tracing glass micropipettes are used to make small injections of tracer in the brain. A problem is that, due to the poor visibility of the tip, the tip of a micropipette often breaks during filling with tracer solution. Therefore, a device was developed to enhance the visibility of the tip of glass micropipettes. The device is based on the principle that light of a light emitting diode (LED) is transmitted through the glass of the wall to the tip of a micropipette. Here, light converges and gives a brightly illuminated spot. In this set up micropipettes can be positioned accurately into a vial with tracer solution even without microscopic guidance.     

Innovative wavelengths in endodontic treatment

BACKGROUND AND OBJECTIVES: The sanitation of the root canal system and the adjacent dentin has always been a key requirement for successful endodontics. In recent years, various laser systems have provided a major contribution to this aim, namely the Nd:YAG-, the 810 nm Diode-, the Er:YAG-, and the Er,Cr:YSGG laser. Numerous studies could prove their efficiency within the endodontic procedure. Recently, two new wavelengths have been introduced to the field of oral laser applications: The KTP laser emitting at 532 nm and the 980 nm diode laser. The present in vitro investigation was performed to evaluate the effects of these laser systems focusing on their antibacterial effect in deep layers of dentin and their impact on the root canal dentin. STUDY DESIGN/MATERIALS AND METHODS: Two-hundred slices of root dentin with a thickness of 1 mm were obtained by longitudinal cuts of freshly extracted human premolars. The samples were steam sterilized and subsequently inoculated with a suspension of either Escherichia coli or Enterococcus faecalis. After the incubation, the samples were randomly assigned to the two different laser systems tested. Each laser group consisted of two different operational settings and a control. The dentinal samples underwent "indirect" laser irradiation through the dentin from the bacteria-free side and were then subjected to a classical quantitative microbiologic evaluation. To assess the temperature increase during the irradiation procedure, additional measurements were carried out using a thermocouple. To assess the impacts on the root canal walls, 20 additional samples underwent laser irradiation at two different settings and were subjected to scanning electron microscopy. RESULTS: Microbiology indicated that both laser systems were capable of significant reductions in both test strains. At an effective output power of 1 W, E. coli was reduced by at least 3 log steps in most of the samples by the tested wavelengths, with the best results for the KTP laser showing complete eradication of E. coli in 75% of the samples. E. faecalis, a stubborn invader of the root canal, showed minor changes in bacterial count at 1 W. Using the higher setting of 1.5 W, significant reductions of E. coli were again observed with both laser systems, where the lasers were capable of complete eradication of E. faecalis to a significant extent. There was no significant relation between the temperature increase and the bactericidal effect. CONCLUSIONS: The present study demonstrates that both wavelengths investigated could be suitable for the disinfection of even the deeper layers of dentin and equal the results achieved by established wavelengths in state-of-the-art endodontics.     

Non-ablative 1,450-nm diode laser treatment of striae distensae

BACKGROUND AND OBJECTIVES: Striae distensae are dermal scars with flattening and atrophy of the epidermis. Successful treatment of these stretch marks has been disappointing. The non-ablative 1,450-nm diode laser has been shown to improve atrophic scars and may be expected to improve striae. As yet, no study has been published to document the effects of this laser on striae. Our aim is to evaluate the efficacy of the 1,450-nm diode laser in the treatment of striae rubra and striae alba in Asian patients with skin types 4-6. STUDY DESIGN/MATERIALS AND METHODS: Striae on one half of the body in 11 patients were treated with the 1,450-nm diode laser with cryogen cooling spray with the other half serving as a control. The following parameters were used: 6 mm spot size and dynamic cooling device (DCD) for 40 milliseconds to protect the epidermis. Patients were randomly assigned to receive either 4, 8, or 12 J/cm2. A total of three treatments were given at 6-week intervals. The following sites were treated: abdomen, arms, back, buttocks, and thighs. Two patients had striae rubra and nine striae alba. Clinical photographs were taken before and after each treatment and analysis was undertaken through photographic evaluation by non-treating physicians. RESULTS: At 2 months after the last treatment, no patients showed any noticeable improvement in the striae on the treated side compared to baseline and to the control areas. Side effects were limited to transient erythema and postinflammatory hyperpigmentation (PIH), which occurred in seven (64%) patients. CONCLUSIONS: The non-ablative 1,450-nm diode laser is not useful in the treatment of striae in patients with skin types 4, 5, and 6.     

Transscleral diode laser therapy for cyclodialysis cleft induced hypotony

In order to evaluate the efficacy of transscleral diode laser therapy for treatment of cyclodialysis cleft associated with ocular hypotony, transscleral diode laser therapy was used in two patients with cyclodialysis cleft. It was applied over the cleft area in two rows of 14 applications in a post-traumatic patient and of 8 applications in a post-trabeculectomy patient at a power setting of 2500 mW and duration of 2000 msec. The clefts were closed with restoration of normal intraocular pressure and recovery of visual function in both patients. Transscleral diode laser therapy seems to be a safe, simple and non-invasive method for closure of the cyclodialysis clefts, especially in patients inappropriate for argon laser photocoagulation and those with opaque cornea.