Ladislav Horak

Chalcogenide glasses and fibers for applications in medicine

Chalcogenide glasses based on suplhides and selenides are very promising materials for various photonic applications, particularly for applications in medicine. Most of current optical fibers have been developed form ultrapure silica. While silica glasses are suitable for optical components in telecommunications they exhibit high losses beyond 2 micrometers - a wavelength range important for clinical practice. Thus special glass materials 9from which fibers could be drawn) should be developed for optical power transmission beyond 2 micrometers . The investigation and preparation of vitreous materials that include sulphide, selenide and selenide- tellurite glass systems together with fluoride and heavy metal oxide glasses on the base of ZrF4, HfF4 and GeO2, TeO2, PbO, respectively are being pursued in our laboratory. This research is aimed at the development of both passive and active (rare-earth doped) optical fibers. In this contribution we concentrate on the doping of chalcogenide glasses by rare earth elements (Er, Pr, Nd). Although the major role of these glasses is assumed in the development of laser power delivery systems for applications in surgery, dentistry, dermatology and ophthalmology, they can equally be used for the diagnostics of human tissues. An example of colon tissue autofluorescence will be given.

Open lung surgery with Nd-YAG Laser

We report on nineteen patients who successfully underwent open lung performance with a Nd-YAG laser in the period December 1987 to August 1988. Reasons for laser operations were lung metastases (twelve cases), lung fibrosis (five patients), one lung cyst and one tuberculoma. We used the Nd-YAG laser in non-contact mode, with focus hand-piece spot size of 1.5 mm, a continual 1064 nm wavelength and a power output 90 W. In these nineteen cases we performed 35 laser photoablations of lung tissue. All patients healed without any serious complications. The major advantage of Nd-YAG laser beam in open lung surgery is in the rapid sealing effect of small airways and of blood vessels up to 3 mm. The Nd-YAG laser seems to be very suitable for operations in lung periphery.

Lesser curve photoseromyolysis with the Nd-YAG laser

We confirmed in animal experiments that the Nd-YAG laser can be used to replace conventional surgical techniques for duodenal ulcer disease—lesser curve seromyotomy, as proposed by Taylor. The experiments suggest that the operative time may be halved using the laser. We confirmed that the ideal laser parameters for this technique were: wavelength 1319nm and power output 15 W, using a contact sapphire tip, with repeated pulses of 0.25 s. Histological studies were performed to show the effect of the laser on the stomach wall and on the vagus nerve. It was shown that the pH was elevated from 1.3 to 6.9 or even higher.The first successful operation on man with this technique was performed in May 1989.

Peroperative optical autofluorescence biopsy--verification of its diagnostic potential.

The authors tested the diagnostic potential of the portable autofluorescence optical system that was developed in the preoperative evaluation of resection margins, and thus of the resection line safety in patients with low-positioned colorectal carcinoma. A total of 217 spectral measurements of the fluorescence properties of normal (117) and malignant (100) tissues in 19 patients with colorectal carcinoma were accomplished. The measured spectra thus acquired were then evaluated using logistic regression. Using the principal component method, the authors selected the 30 and 40 most significant wavelengths, respectively, which they then used to construct the logistic model. The model met the basic criteria of statistical significance. The classification power of the model was 79.7% (for 30 wavelengths) and 82.5% (for 40). Statistical discrimination was 0.88 and 0.91, respectively. These results confirm that the optical setup that we selected is suitable for the peroperative testing of the distal resection line. It is capable of differentiating with 90% confidence pathological tissue and thus of reliably guiding further histological processing.

Photodynamic Therapy of Human Colorectal Carcinoma Cell Line

Colorectal cancer is one of the most common cancers in Europe and North America and it is the most common gastrointestinal carcinoma. The population in the Czech Republic has a higher incidence of colorectal carcinoma compared to other countries. Efforts are underway to develop better screening strategies and novel therapies to improve patient survival rates. Despite all efforts, colorectal cancer remains one of the leading causes of death from cancer. Photodynamic therapy (PDT) is an established modality for the treatment of various diseases. The PDT procedure involves the administration of a photosensitizer followed by illumination. The anti-tumor effects result from direct killing of malignant cells, shutting down of the tumors vasculature, and the promotion of an immune response. In our experiment, we examined the effects of phototherapy with disulfonated hydroxyaluminum phthalocyanine (Al(OH)S2Pc) on the growth of colorectal carcinoma cells, in an effort to offer a new treatment modality for patients with this disease.

Autofluorescence spectroscopy of colorectal carcinoma: ex vivo study

Diagnosis established by means of fluorescence spectroscopy is currently used in the field of urology and bronchology. Its major advantage is that it allows the diagnosis of epithelial dysplasia or malignant proliferation even if routine diagnostic endoscopy fails to reveal any macroscopic changes. The authors present results of their observations that deal with fluorescence diagnosis of colorectal carcinoma. They examined the wet microscopic mounts of healthy colon mucosa and compared them to that prepared from colon mucosa affected by adenocarcinoma. The diagnosis of adenocarcinoma was verified by using clinical and histology means. Fluorescence spectra of tissue samples, excited by means of 488 and 514.5 nm lines of Ar ion laser and/or by He-Ne laser line 632.8 nm, have been studied. This study demonstrated differences in both the spectral shape and in the signal intensity (at unchanged spectral shape) of photoluminescence spectra emitted from tissue affected by adenocarcinoma as compared to that of healthy colon mucosa. The results encourage us to continue the study aimed at development of the diagnostic system usable in the clinical practice.

393 POSTER Transrectal stent in endoscopic palliative therapy of malignant stenosis of the rectum

BACKGROUND/AIMS To check the feasibility and safety of endoscopic stent introduction in colorectal cancer therapy. METHODOLOGY A total of 62 patients with inoperable tumors of the rectum and rectosigmoid were treated by introducing stents. Stents were also introduced in 3 patients with advanced prostate tumors obturating (narrowing) the rectum. In 3 cases, the stents were introduced under X-ray control. In all other cases, an endoscopic approach to the stent introduction was employed. RESULTS Stents could not be introduced in 4 patients. In 1 case, the bowel was perforated above the malignant (tumorous) stenosis. In 4 patients, it was necessary to remove the stents because of dislocation. Growth of the tumor into the stent was not experienced. Experience with acute obstruction treatment was minimal as only two patients were treated for this indication. CONCLUSIONS Endoscopic stent introduction is a safe palliative procedure making it possible to improve the quality of life of patients with inoperable tumors of the rectum and rectosigmoid.

Management of the Perforating Colon with Stercoral Peritonitis

AbstractPatients and Method: In the course of the recent 18 years, a total of 137 patients with perforated colon were treated at the Department of Surgery of the Charles University Hospital in Prague 10. All patients with perforation suffered from peritonitis. Perforations accounted for 3% of patients operated on during the same time period at our Clinic for some sort of colon lesions. The most frequent primary pathology to which the perforation could be attributed was either neoplasia (54) or diverticulitis (51) and less frequent were artificial injury (23), ischemic lesion (seven) and ulceration (two). All patients underwent surgery after a short preparatory phase. Results: 44 of our patients died with an average survival time of 6.6 days and their mean age was 75 years. Among all treated subjects, 85 patients experienced some sort of complications. Conclusions: We wish to emphasize that the ultimate decision on the surgical procedure is taken after laparotomy and must weigh several factors such as the extent and duration of peritonitis, character of the causal pathological lesion and its localization, age and the overall physical condition of each individual patient. As far as the circumstances permit, the principal aim of the surgical treatment is to remove the source of infection together with the primary pathological lesion. Preferable are one-stage resection procedures with anastomosis or Hartmanns procedure. It is obvious that local findings and the general state of the patients often contraindicate a radical surgery, and one must resort to a derivative procedure and drainage, or possibly suture. Such operations are of course fraught with a high mortality rate.ZusammenfassungPatienten und Methode: Im Verlauf der letzten 18 Jahre wurden 137 Patienten mit Kolonperforation in der Abteilung für Chirurgie des Universitätsklinikums in Prag operiert. Alle Patienten mit Perforation litten gleichzeitig auch an einer Peritonitis. Bei 3% der operierten Patienten kam es während des gleichen Zeitraums zur Perforation aufgrund verschiedener Kolonläsionen. Die häufigsten Primärerkrankungen, denen die Perforation zugeordnet werden konnte, waren Neoplasien (54) oder Divertikulitis (51) und mit geringerer Inzidenz iatrogene Verletzungen (23), Ischämien (sieben) und Ulzera (zwei). Alle Patienten wurden nach einer kurzen Vorbereitung operiert. Ergebnisse: 44 Patienten verstarben innerhalb einer durchschnittlichen Überlebenszeit von 6,6 Tagen. Ihr Durchschnittsalter lag bei 75 Jahren. Insgesamt kam es bei 85 aller behandelten Patienten zu diversen Komplikationen. Schlussfolgerungen: Wir möchten hervorheben, dass die ultimative Entscheidung der Operationsmethode nach der Laparotomie getroffen wurde und verschiedene Faktoren umfasste wie Dauer der Peritonitis, Art der kausalen Erkrankung und ihre Lokalisation, Alter und Gesamtgesundheitszustand jedes einzelnen Patienten. Soweit es die Umstände erlaubten war die Hauptzielsetzung der Operation die Entfernung der Infektionsquelle zusammen mit dem primären Erkrankungsherd. Die Methode der Wahl sind einseitige Resektionen mit Anastomose oder die Hartmann-Methode. Es liegt auf der Hand, dass lokale Befunde und der generelle Gesundheitszustand der Patienten häufig einen radikalen Eingriff kontraindiziert erscheinen lassen und dass deswegen mehrzeitige Verfahren mit Stuhlableitung und Drainage oder möglicherweise Nahtanlage eingesetzt werden müssen. Diese Eingriffe sind naturgemäß mit einer hohen Mortalitätsrate behaftet.

Invasive leg vein treatment with 1064/1319 Nd:YAG laser: combination with dye laser treatment

More than 2 500 leg veins patients were treated with dye laser / ScleroPlus, Candela, USA / successfully in our clinic and we use this therapy as the basic cosmetics treatment. But especially diameter of leg vein is limiting factor. Very often we have to treat some cases that are not ideal for classical surgical or for dye laser method. We decided to make invasive perivenous laser coagulation. We adapted original Czech 1064/1319 nm Nd:YAG laser / US patent pending /, which is new combine tool, for invasive application. Principe: After we have penetrated the cutis with laser fiber we coagulate leg veins during slowly perivenous motion. Perfect preoperative examination is a condition of success. After 15 months we have very interesting results. Some patients / 15%/ were perfect treated only with this possibility but excellent results are acquired from combination with dye laser.

Special glasses for passive and active IR fibers for medical and biomedical applications

General chemical compositions of prepared glasses with low OH group concentrations are Ge0.25Ga0.10S0.65, Ge0.25Ga0.05As0.05S0.65, (TeO2)x - (PbCl2)1-x with x equals 0.4 to 0.6 and (TeO2)x - (ZnO)1-x with x equals 0.75 to 0.80. Samples doped with 500 to 12000 ppm rare earth in weight were prepared. Rare earth doped glasses are homogeneous when RE concentration is less than 3000 ppm. Heterogeneous inclusions arise beyond 1000 ppm RE when doping is made with chloride or oxide. Electron microscopy, absorption and fluorescence measurements have been made. YAG:Nd. Ar, He-Ne lasers were used for excitation of photoluminescence. The color and optic quality of the tellurite glasses depend on crucible materials. Rare earth doping results in visible defects or inhomogeneities when concentration is larger than 1000 ppm. The chemical composition and the optical absorption of doped and undoped samples was examined. Fluorescence intensity of Pr and Dy is smaller in these HMO glasses than in the sulfide glasses, which results from higher phonon energy and higher OH concentration. Further development is required for future applications.