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LASER-INDUCED EVAPORATION OF (FECP(CO)2[CHCH2C(CN)2C(CN)2CH2]) AND SOME ANALOGOUS COMPOUNDS FOR THEIR MASS-SPECTROMETRIC CHARACTERIZATION
No full textPhotosensitization of urinary stones to improve the lithotripsy with dye and alexandrite laser.
No full textTransurethral laser surgery with a conventional modified resectoscope.
No full textA new 1,800-microns side fiber made of pure silica with laser beam deviation of 82 degrees and divergence of 18 degrees was inserted into a modified transurethral resectoscope and used to treat in vitro some prostates removed during radical prostatectomy. Sterilization of prostatic tissue with a depth of penetration of 12 mm was observed after treatment with 20 W for 2 min. Irradiation with 60 W for 1 min produced vaporization and explosion of the tissue and a depth of penetration of 15 mm. The laser resectoscope was then successfully employed for the treatment of 6 cases of benign prostatic hyperplasia (BPH) as well as in high risk patients with bulky bleeding bladder tumors (4 cases) and with transitional carcinoma of the prostate invading the parenchyma (2 cases). 3 patients with small size BPH underwent only laser irradiation. All others were submitted to traditional transurethral resection followed by laser treatment with Nd: YAG using the same instrument. Our laser resectoscope lowers costs since the side fiber is reusable for 4-5 treatments and brings laser treatment nearer to traditional endoscopic treatment, thereby making its application more comfortable for the urologist
Plasma bubble formation laser induced by holmium: an in vitro study.
No full textOBJECTIVES: To use the elementary physical measurements of temperature and size to prove that the thermal effects produced by the holmium laser's pulses are due to the formation of a plasma bubble. The physical phenomenon related to high temperatures generated during procedures with the holmium laser (holmium:yttrium-aluminum-garnet) was the object of our interest. METHODS: Using a double micrometric slide attached to a 550-microm optic fiber and two thermocouples submerged in water, a series of pulses of 0.8 J at 10 to 30 Hz was delivered from a holmium:yttrium-aluminum-garnet laser, and we recorded temperatures on both frontal and lateral planes. Subsequently, samples of prostatic tissue and small stones were treated with 1.5 J at 20 Hz on both frontal and lateral planes. RESULTS: Treatment with 1.5 J at 30 Hz (frontal plane) and with 1.5 J at 20 Hz (lateral plane) produced the ablation of the structure of the thermocouple at 2 mm and 1 mm, respectively, indicating plasma formation. The dimensions of the bubble after the delivery of 1.5 J at 20 Hz was 2 x 1.5 mm. Coagulation of the prostatic tissue took place at 1 mm from the plasma bubble, on both frontal and lateral planes. CONCLUSIONS: The plasma bubble that forms at the tip of the fiber connected to the holmium:yttrium-aluminum-garnet laser makes it possible to work on stones and soft tissues. The coagulation of the prostatic tissue is caused by the hot water-vapor bubble that forms on the edge of the plasma bubble. During lithotripsy, guidewires and baskets within the expansion area of the plasma bubble risk damage
Photosensitization of cystine stones to induce laser lithotripsy
No full textWe report the preliminary results of laser lithotripsy of cystine stones accomplished in 2 patients with the use of a new method of photosensitization. Transurethral rigid ureterorenoscopy was performed with an 8.5F instrument to reach 0.8 and 1.8 cm. stones located in the right and left lumbar ureters, respectively. A 320 mu. fiber was then inserted and pushed into contact with the stone. Then, 400 preliminary impulses were released from a pulsed dye laser (504 nm) with energy output at 140 mJ. and at a rate of 5 Hz. without any visible modification of the stone structure. The saline solution used as irrigation fluid was then substituted with a 2% solution of rifamycin. Totals of 95 and 152 impulses released at the same energy output previously used were then sufficient to produce a satisfactory fragmentation of the stone in both cases. Sonography and excretory urography showed no alterations of the treated urinary tract in either case. The use of rifamycin in the irrigation fluid is suggested for laser treatment of hard or nonabsorbent stones, since this substance favors optical coupling and lowers the threshold of plasma formation on the surface of the stone
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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