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PubMed1998

[Thorium: analysis and dosimetry of thorium welding electrodes].

The use of thoriated tungsten electrodes may be at the origin of a potential hazard for the personnel involved in the use of electrodes, as well as the general population. To assess this hazard, the electrode radioactivity measurements by alpha and beta counting has been conducted. The radioelements were identified by alpha and gamma spectromety. It appeared that there was a radioactive disequilibrium between thorium-232 (Th-232) and it daughters atoms. Additionally, some thorium 230 (Th-230) belonging to the uranium chain, was present. The chemical separation and the milling processing had affected the radioactive composition and the thorium in the electrodes, doesn't exactly corresponds to natural thorium. Radiation doses were also assessed: film and photoluminescence dosimetry were undertaken. Finally smears method showed a alpha removable area contamination. Even if the hazard is weak. As a matter of fact, it must not be neglected because it was complex, for the thorium was always accompanied by Th-232 progeny, alpha emitters but also beta and gamma emitters.

Humans↗
PubMed1995

New technique for laryngotracheal mucosa transplantation. 'Stamp' welding using indocyanine green dye and albumin interaction with diode laser.

OBJECTIVE: To investigate (1) the possibility of survival of free mucosa "stamp" grafts fixed in the airway with a new technique using indocyanine green-dyed albumin solder activated with a diode laser and (2) the degree of improvement of wound healing in the airway by applying modified microskin transplantation techniques from burn surgery to cover a relatively large wound with a few small pieces of mucosa anchored in place with the previously mentioned technique. DESIGN: Three (one control and two experimental) rectangular (10 x 8 mm) wounds in tracheal mucosa were produced in four experimental animals (dogs) using a carbon dioxide laser. The control wound was left uncovered. In the first experimental wound, a mucosal flap was raised and then fixed in place by a trapdoor flap method. In the second experimental wound, two small (each 2 x 3 mm) autogenous mucosa grafts were anchored onto the surface with indocyanine green-dyed albumin activated with an 810-nm diode laser. Histomorphologically, the postoperative results from three wounds were compared. RESULTS: The experimental wounds were completely covered by regenerated squamous cells in 1 week and by ciliated epithelium in 2 weeks after the operation despite the discrepancy in size of the graft to wound area (1:6.7) covered with the stamp mucosa. No thermal damage from the diode laser was noted in the second experimental wounds. In the control wounds, no coverage was observed at 1 week, and only squamous cells were noted 2 weeks postoperatively. All the wounds had normal ciliated epithelium coverage at 4 weeks. CONCLUSIONS: Transplanted stamp grafts provided similar or better healing than trapdoor flap transplants. This new technique made endoscopic mucosal grafting possible and offers a potential breakthrough in the management of laryngotracheal stenosis.

Albumins↗
PubMed1999

Effect of laser welding with human serum albumin on the expression of P-selectin on platelets.

BACKGROUND AND OBJECTIVE: Artery repair by means of laser energy induces activation of platelets with a risk of thrombosis and local inflammatory reactions. The aim of this study was to investigate the effect of human serum albumin, the most common solder in laser surgery, on platelet activation. STUDY DESIGN/MATERIALS AND METHODS: Platelet activation was evaluated in canine blood by using two-color flow cytometry with a phycoerythrin-labeled antibody to a common platelet marker, glycoprotein IIb/IIIa and fluorescein isothiocyanate-labeled antibody to a platelet activation molecule, P-selectin. Human serum albumin was applied in vitro and in vivo, as a solder during laser reconstruction of canine arteries. RESULTS: In vitro, albumin significantly (P < 0.01) reduces the expression of P-selectin on platelets. This is most likely related to the blockage of P-selectin by albumin, which binds to the platelet surface, as confirmed by flow cytometry with fluorescein isothiocyanate-labeled albumin. In vivo, application of albumin solder tended to result in a lower percentage of P-selectin-expressing platelets in laser-repaired arteries compared to suture-repaired arteries. CONCLUSION: Albumin decreases the percentage of P-selectin-expressing platelets in vitro. Further research may allow the platelet activation inhibiting properties of albumin to be further optimized in vivo.

Animals↗
PubMed2000

Semi-solid albumin solder improved mechanical properties for laser tissue welding.

BACKGROUND AND OBJECTIVE: A semi-solid albumin solder formulated with hydroxypropylmethylcellulose (HPMC) was designed to improve the characteristics of liquid and solid solders. STUDY DESIGN/MATERIALS AND METHODS: Acute tensile strengths were determined on canine small bowel in vitro by using liquid 50% bovine serum albumin (BSA), semi-solid 48% BSA with HPMC, and solid 60% BSA solder. Long-term healing of liquid and semi-solid solders, compared with a suture control, was evaluated in a porcine skin model, with tensile strength as well as histologic findings obtained on postoperative day 7. RESULTS: Acutely, semi-solid solder demonstrated a significantly (P < 0.05) higher tensile strength when compared with liquid or solid solder. At 7 days, HSA semi-solid and BSA semi-solid had significantly (P < 0.05) higher tensile strength than suture control; however, no differences were seen for liquid or solid solder groups. No differences in histology were appreciable between any of the solder groups in a porcine skin model. CONCLUSION: Acutely and at 7 days, semi-solid solder was stronger than 50% liquid albumin with better handling characteristics.

Animals↗
PubMed2003

Preliminary biocompatibility experiment of polymer films for laser-assisted tissue welding.

BACKGROUND AND OBJECTIVES: The purpose of this study was to examine the impact of a polymer film for liquid solder strength reinforcement on the short term healing of a wound closed by laser-tissue soldering. MATERIALS AND METHODS: Full thickness incisions created on the dorsum of Sprague-Dawley rats were closed by laser-tissue soldering: albumin solder with Indocyanine Green (ICG) dye was inserted between the incision edges and photothermally coagulated with a diode laser. A poly(DL-lactic-co-glycolic acid) (PLGA) polymer film was implanted subcutaneously in the bottom of the incision (controls had no film). Specimens were harvested at 0, 3, 7, and 14 days for breaking strength testing and histological analysis. RESULTS: Breaking strengths of the controls at 0 and 14 days were statistically stronger than the specimens with the implanted films (t-test, P < 0.05). A slight difficulty in apposing the wound edges due to the film presence may have contributed to the low acute strengths. Interference with the wound contraction process by the films possibly contributed to the lower breaking strength at 14 days. Wound histology indicated a mild foreign body reaction to the polymer film material. CONCLUSIONS: The polymer film was well tolerated by the tissue, and the tissue response to the material was consistent with that seen in the literature. The breaking strength differences between control and film-implanted specimens at 0 and 14 days were probably the result of mechanical complications (tissue apposition and wound contraction) due to the presence of the film, and not due to the film material itself. The use of polymer film patches for liquid solder reinforcement and breaking strength enhancement may have certain application specific issues that need to be addressed. Strategies to account for these issues require further research.

Animals↗
PubMed1995

Comparison of laser vascular welding, interrupted sutures, and continuous sutures in growing vascular anastomoses.

BACKGROUND AND OBJECTIVES: The argon laser-assisted vascular anastomosis may solve the problems of conventional sutured anastomosis, such as vascular stenosis and arrest of growth owing to a foreign-body reaction to suture material. STUDY DESIGN/MATERIALS AND METHODS: Twelve argon laser-assisted vascular anastomoses, seven conventional anastomoses with interrupted sutures, and five conventional anastomoses with continuous sutures were performed in 12 young mongrel dogs. RESULTS: Five months later, the external diameter at the anastomosis had increased 70.5% in the laser group, 67.0% in the interrupted suture group, and 22.9% in the continuous suture group. Histological examination of the laser-assisted anastomoses showed almost complete healing, with no granulomatous response around the anastomotic site. In the interrupted suture group, marked scaring and foreign body reactions were observed on the vessel wall at the site of the anastomosis. The continuous suture group showed more remarkable disorientation of the vascular layer and intimal hyperplasia than the interrupted suture group. CONCLUSION: Vascular anastomosis using the argon laser offers advantages over the conventional procedure in growing vessels.

Anastomosis, Surgical↗
PubMed1987

Review of tissue welding applications in neurosurgery.

New technical advances have made feasible the utilization of low-powered laser energy for constructive applications. Experience with laser bonding of blood vessels, peripheral nerves, and dura has been obtained. These studies are summarized, and the future potential of laser bonding of tissues of the central nervous system is discussed.

Animals↗
PubMed1988

Laser welded vascular anastomosis. Comparison of CO2 and neodym yag laser techniques.

A comparative study was undertaken to investigate the application of a specially adapted microsurgical Neodymium Yag Laser system with a wavelength of 1,319 microns and a CO2 laser system for laser assisted microvascular end-to-end anastomosis (LAMA) of the rat femoral artery. Conventionally sutured anastomoses served as controls. Postoperative investigations included patency tests, light microscopy and tensile strength measurements. Both laser systems seem to be equally suitable for LAMA: The patency rates do not differ from those of sutured anastomoses and formation of microscopically small aneurysms occurred predominantly in control animals and only once in laser groups. The clamp time needed for LAMA was half the time that was needed for sutured anastomoses. Wound healing in all groups was similar with less fibrotic reactions and less foreign body granulomas in laser groups. At all intervals tensile strength was significantly higher for sutured anastomoses while differences between the CO2- and the ND: Yag-laser groups were not statistically significant. Potential applications in urology include microvascular anastomoses in erectile dysfunction, pediatric and reconstructive urology.

Anastomosis, Surgical↗
PubMed2001

Laser welding of vesicovaginal fistula.

The management of vesicovaginal fistula remains a source of debate, despite extensive literature on the subject. It is difficult to prove the superiority of one surgical technique over another by randomized trials, given the variabilities of fistula etiology, the location and clinician expertise. Small epithelized fistulae following conservative treatment and residual or recurrent cases following transabdominal or transvaginal repair pose a therapeutic challenge. A case of a small vesicovaginal fistula following abdominal hysterectomy is presented, in which a successful outcome was achieved using endoscopic Nd-YAG laser fulguration.

Electrocoagulation↗
PubMed2006

The CNS synapse revisited: gaps, adhesive welds, and borders.

Although processes leading up to the point of synapse formation are fairly well understood, the precise sequence of events in which the membranes of two separate cells "lock in" to form a mature synaptic junctional complex is poorly understood. A careful study of the molecules operating at the synapse indicates that their roles are more multifarious than once imagined. In this review we posit that the synapse is a functional organelle with poorly defined boundaries and a complex biochemistry. The role of adhesion molecules, including the integration of their signaling and adhesive properties in the context of synaptic activity is discussed.

Animals↗
PubMed2005

A novel solvent-free method for the manufacture of biodegradable antibiotic-capsules for a long-term drug release using compression sintering and ultrasonic welding techniques.

This report was to develop a novel solvent-free method for the manufacture of biodegradable capsules for a long-term drug delivery. To manufacture an antibiotic capsule, polylactide-polyglycolide copolymers were pre-mixed with vancomycin. The mixture was then injection compression molded to form a cylinder with a cover of 8mm in diameter. After the addition of gentamicin sulfate into the core, an ultrasonic welder was used to seal the capsule. An elution method and an high-performance liquid chromatography assay were employed to characterize the in vitro release rates of the antibiotics over a 30-day period. It was found that biodegradable capsules released high concentration of vancomycin and gentamicin (well above the minimum inhibition concentration) in vitro for the period of time needed to treat bone infection; i.e., 2-4 weeks. A bacterial inhibition test was carried out to determine the relative activity of the released antibiotics. The diameter of the sample inhibition zone ranged from 3 to 18 mm, which is equivalent to 16.7-100% of relative activity. By adopting this novel technique, we will be able to manufacture biodegradable capsules of various medicines for long-term drug delivery.

Anti-Bacterial Agents↗