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PubMed1993

Argon laser-welded bovine heterograft anastomoses.

UNLABELLED: This study evaluated the strength of laser-welded arteriovenous shunts established using St. Jude BioPolyMeric vascular grafts. The arterial anastomoses of the biological graft were laser welded with and without the addition of soluble collagen or fibrin sealant. In four dogs, 16 arteriovenous grafts were implanted between the femoral artery and vein or the carotid artery and jugular vein using a 6 cm long, 4 mm internal diameter prosthesis. The 16 arterial anastomoses were evenly divided into four groups: sutured control, laser welded (LW), LW with soluble collagen applied immediately before and during welding, and LW with fibrin sealant applied after welding. All arterial control and venous anastomoses were sutured using continuous 6-0 polypropylene suture. All LW anastomoses were initially divided into six 5 mm long segments using six evenly spaced 6-0 polypropylene stay sutures. Each segment was laser welded using 15 to 18 5-sec pulses of the 0.5 W (7.5 W/cm 2) argon laser energy delivered via a 300 mum fiber while cooling the tissue with slow-drip saline irrigation. Blood flow was established and maintained through each anastomosis for 1 h. The vessels were then controlled, and anastomotic bursting pressure was determined with infusion of heparinized blood. RESULTS: An additional hemostatic suture was required in 3 LW anastomoses (2 LW, 1 LW with collagen). Mean bursting pressures (mm Hg) of the arterial anastomoses were as follows: sutured controls 165 +/- 159, LW 144 +/- 58, LW and collagen 93 +/- 47, LW and fibrin sealant 181 +/- 45.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1997

Carbon dioxide laser tissue welding: an alternative technique for tubal anastomosis?

Microsurgical tubal anastomosis is the gold standard for treatment of tubal occlusion. The present study was performed to establish the feasibility of tubal anastomosis by welding tissue with a defocused CO2-laser beam during laparotomy and with an endoscope. In an animal experiment, 70 white New Zealand rabbits were randomized in 2 study groups (E1, E2) and 3 control groups (C1, C2, C3) as follows: C1, 10 animals, no operation, as controls for the efficiency of the insemination technique; C2, 5 animals, spontaneous healing after tubal segment resection, to quantify spontaneous recanalization of the tube; C3, 15 animals, microsurgical end-to-end adaption after tubal segment resection; E1, 20 animals, laser welded anastomosis after segment resection via laparotomy; E2, 20 animals, laparoscopic laser welded anastomosis after segment resection. The pregnancy rate in C1 was 80%. None of the animals in C2 but 60% of the rabbits in C3 conceived. After sutureless anastomosis by laser welding 50% of the laparotomized, and 40% of the laparoscopically operated group became pregnant. Morphological examination of the oviducts after relaparotomy showed comparable patency rates of 70% in C3, 70% in E1, and 65% in E2. Whereas no dehiscence of anastomoses was observed in C3, 20% of the welded tubes in E1 and 22.5% in E2 were dehiscent. Tubal anastomosis took approximately three times as long laparoscopically as during laparotomy. Thus, laser welding as a sutureless alternative technique of tubal anastomosis should be viewed critically. A reduction of sutures through laser-assisted anastomosis might, however, be considered.

Anastomosis, Surgical↗
PubMedDate not supplied

Laser vascular welding in biologic grafts.

This study evaluated the possibility and efficacy of laser welding in biologic vascular grafts. Grafts were anastomosed to 21 canine peripheral (femoral and/or carotid) arteries or coronary arteries with a Nd-YAG laser using the contact method. The laser welds were fashioned using 1-1.5 W power for 1-3 sec. The grafts used were heparinized canine carotid artery cross-linked with polyepoxy compounds. The welding was a success in 92% (22/24) of the peripheral artery and 83% (5/6) of the coronary artery procedures. The early patency rate was 100%. The anastomotic sites were strong enough to withstand high pressure (more than 300 mmHg of arterial pressure). Histologic examination was performed on days 0 and 3, 1 week, 3 weeks, or more than 1 month postoperatively to compare the progression of healing. The laser welded sites had a smooth external surface and minimal damage of the internal layer, with minimal inflammatory response and no pathologic granulation. The welded sites fused strongly after 1 postoperative week. In conclusion, an Nd-YAG laser, using a contact method, could successfully weld peripheral and coronary arteries to biologic vascular grafts.

Anastomosis, Surgical↗
PubMedDate not supplied

Experimental study on the healing process following laser welding of the cornea.

An experimental study evaluating the application of laser welding of the cornea and the subsequent healing process is presented. The welding of corneal wounds is achieved after staining the cut walls with a solution of the chromophore indocyanine green, and irradiating them with a diode laser (810 nm) operating at low power (60 to 90 mW). The result is a localized heating of the cut, inducing controlled welding of the stromal collagen. In order to optimize this technique and to study the healing process, experimental tests, simulating cataract surgery and penetrating keratoplasty, were performed on rabbits: conventional and laser-induced suturing of corneal wounds were thus compared. A follow-up study 7 to 90 days after surgery was carried out by means of objective and histological examinations, in order to optimize the welding technique and to investigate the subsequent healing process. The analyses of the laser-welded corneas evidenced a faster and more effective restoration of the architecture of the stroma. No thermal damage of the welded stroma was detected, nor were there foreign body reactions or other inflammatory processes.

Animals↗
PubMed2005

Process control of laser conduction welding by thermal imaging measurement with a color camera.

Conduction welding offers an alternative to keyhole welding. Compared with keyhole welding, it is an intrinsically stable process because vaporization phenomena are minimal. However, as with keyhole welding, an on-line process-monitoring system is advantageous for quality assurance to maintain the required penetration depth, which in conduction welding is more sensitive to changes in heat sinking. The maximum penetration is obtained when the surface temperature is just below the boiling point, and so we normally wish to maintain the temperature at this level. We describe a two-color optical system that we have developed for real-time temperature profile measurement of the conduction weld pool. The key feature of the system is the use of a complementary metal-oxide semiconductor standard color camera leading to a simplified low-cost optical setup. We present and discuss the real-time temperature measurement and control performance of the system when a defocused beam from a high power Nd:YAG laser is used on 5 mm thick stainless steel workpieces.

Journal Article↗
PubMed2006

Attachment of Listeria monocytogenes to an austenitic stainless steel after welding and accelerated corrosion treatments.

Austenitic stainless steels, widely used in food processing, undergo microstructural changes during welding, resulting in three distinctive zones: weld metal, heat-affected zone, and base metal. This research was conducted to determine the attachment of Listeria monocytogenes in these three zones before and after exposure to a corrosive environment. All experiments were done with tungsten inert gas welding of type 304 stainless steel. The four welding treatments were large or small beads with high or low heat. After welding, all surfaces were polished to an equivalent surface finish. A 10-microl droplet of an L. monocytogenes suspension was placed on the test surfaces. After 3 h at 23 degrees C, the surfaces were washed and prepared for scanning electron microscopy, which was used to determine attachment of L. monocytogenes by counting cells remaining on each test surface. In general, bacteria were randomly distributed on each surface type. However, differences in surface area of inoculum due to differences in interfacial energy (as manifested by the contact angle) were apparent and required normalization of bacterial count data. There were no differences (P > 0.05) in numbers of bacteria on the three surface zones. However, after exposure to the corrosive medium, numbers of bacteria on the three zones were higher (P < 0.05) than those on the corresponding zones of noncorroded surfaces. For the corroded surfaces, bacterial counts on the base metal were lower (P < 0.05) than those on heat-affected and weld zones.

Bacterial Adhesion↗
PubMed2001

[Effects of laser welding on ceramic fused to metal].

OBJECTIVE: This study was aimed to investigate the bonding effect of laser welding on ceramic fused to metal. METHODS: Ten laser welded CW-PA ceramo-alloy rods were fused with porcelain at fusion zone. The porcelain-metal bond strength was measured with pull-through test. SEM examination and EDAX analysis were performed. Ten non-welded CW-PA ceramo-alloy pull-rod plates were used as comparison. RESULTS: The results showed that the bond strength of laser welded sample was 41.32 +/- 6.69 MPa, approaching to 45.71 +/- 9.98 MPa of the non-welded sample (P > 0.05). The microscope displayed the interface compacted union of the two phase boundary. There was no change in the elements and their ratio at the fusion zone. CONCLUSION: These results indicate that laser welding does not affect ceramic fused to metal.

Dental Porcelain↗
PubMed1995

Laser welding of everted enterotomies in rats.

OBJECTIVE: To assess the feasibility of welding everted enterotomies with laser. DESIGN: Open study. MATERIAL: 21 Male albino rats (mean weight 152 g). INTERVENTIONS: 28 Full thickness enterotomies (involving 50% to complete circumference of the rat's small intestine) were welded with an Nd-YAG laser non-contact fibre. The bowel ends were everted and held tightly with simple non-toothed forceps during welding. MAIN OUTCOME MEASURE: Success or failure judged by the naked eye. RESULTS: Welding was successful in 14/20 (70%) enterotomies that involved half the circumference of the small bowel but in only 3/8 (38%) when the enterotomy extended further because of inadequate tissue opposition. A new visual end point of welding was noticed. CONCLUSION: Laser welding of everted enterotomies is safe for small enterotomies as judged by the naked eye, but controlled studies are needed before the technique can be tested in humans.

Anastomosis, Surgical↗
PubMed2002

Interstitial pulmonary fibrosis after severe exposure to welding fumes.

BACKGROUND: Interstitial pulmonary fibrosis (IPF) is reported after long term, severe exposure to welding fumes in poorly ventilated workplaces. METHODS: Fifteen welders with IPF were examined--13 in our outpatient clinic--from 1990 to 1997. Occupational histories and examinations, lung function analyses, symptoms and clinical findings, histological analyses in 13 patients partly including SEM/EDX-analyses, chest X-rays, chest computed tomographies were conducted. RESULTS: Duration of work as welders was 28 years and the cumulative dose of welding fumes 221 mg/m(3) x years (median). Lung function studies found pattern of restriction or combined restriction-obstruction, lower diffusion capacity, and reduced blood oxygen tension at exercise. Histologically, patchy interstitial fibrosis was noted. Accumulations of particulate matter typically for welding fume were detected. EDX showed increase of iron load and close topographical relationship to welding fume particles embedded in areas of scattered fibrosis. CONCLUSION: While epidemiological data are limited, it is reasonable to conclude that a causal relationship exists between IPF in welders with long term exposure to high concentrations of welding fumes.

Adult↗
PubMed2006

Immediate hypersensitivity type of occupational laryngitis in a welder exposed to welding fumes of stainless steel.

BACKGROUND: Although upper respiratory symptoms have been reported to occur in welders, occupational laryngitis of immediate hypersensitivity type due to welding fumes of stainless steel has not been previously reported. METHODS: Occupational laryngitis was diagnosed based on the specific challenge test combined with the patient's history of occupational exposure and laryngeal symptoms. RESULTS: During the past few years, a 50-year-old man had started to experience laryngeal symptoms while welding stainless steel. The welding challenge test with stainless steel caused significant changes in the laryngeal status 30 min after challenge: increased erythema, edema, and hoarseness of the voice. The referent inhalation challenge test by welding mild steel was negative. CONCLUSION: The welding of stainless steel should be included in the etiological factors of occupational laryngitis of immediate hypersensitivity type.

Humans↗
PubMed1989

Dye-enhanced laser tissue welding.

For vascular anastomosis, use of topical photosensitizing dye enhances selective delivery of laser energy to target tissue, thus reducing the amount of collateral thermal injury and threshold power required for welding. For fluorescein isothiocyanate (FITC)--stained rabbit aorta in vitro, the threshold for tissue blanching was 15 seconds of 100 mW exposure of cw argon ion laser compared with 15 seconds at 300 mW for unstained tissue. The threshold power density needed for argon laser welding of abdominal aortotomies in rabbits in vivo was 3.8 W/cm2 with FITC and 7.6 W/cm2 without the dye. However, bursting pressures for the two groups (164 mm Hg with FITC, 147 mm Hg without FITC) were not significantly different. Histology revealed decreased collateral thermal damage in FITC-enhanced welds. Use of photosensitizing dyes for tissue welding is feasible and may allow arterial welding with lower power laser systems and cause less thermal trauma by lowering threshold power levels.

Animals↗
PubMed1985

Exposure in welding of high nickel alloy.

Nickel (Ni) levels in air during welding of high-Ni alloy (75% Ni) were very high (mean 0.44 mg/m3, range 0.07-1.1 mg/m3; 20 person-days of measurements). In six welders the Ni level in urine after four weeks of vacation was slightly but statistically significantly enhanced as compared to ten unexposed controls (means 8.7 vs 5.1 micrograms/l; P less than 0.005). The level on Monday mornings increased somewhat during a period of six weeks of high-Ni alloy welding (mean 13 micrograms/l; P less than 0.05). The level was slightly higher Thursday afternoon (mean 18 micrograms/l; P less than 0.0001). The data indicate the existence of a very slow pool of Ni in the body in addition to a faster one. There was no correlation between Ni levels in air and urine. Thus, in spite of the very high Ni levels in air, urinary Ni levels were thus of little use for biological monitoring of exposure and risk during high-Ni alloy welding. All eleven welders studied reported one or more symptoms (irritation of upper airways, headache, tiredness) as occurring more often (P less than 0.006) during high-Ni welding than when welding ordinary stainless steel. Lung-functions studies were normal.

Adult↗
PubMed1994

Chromosome damage in lymphocytes of stainless steel welders related to past and current exposure to manual metal arc welding fumes.

Cytogenetic damage was studied in lymphocytes from 42 welders using the manual metal arc (MMA) method on stainless steel (SS). A detailed characterization of previous exposure by job interviews, and for current exposure with personal air sampling and biological monitoring of chromium (Cr) and nickel (Ni) in blood and urine, was done for 32 of these welders. A subgroup of 20 welders was studied before and after 1-4 months of MMA/SS welding. A matched reference group I, and a larger reference group II were established for comparison. A significant increase in chromatid breaks (1.4 vs. 0.9 and 0.8 for group I and II) and for cells with aberrations (2.2 vs. 1.6 in group II) was found in the welders. An even larger difference was found when comparing non-smoking welders with their non-smoking referents. No synergistic effect between smoking and MMA/SS welding fumes was observed for any type of aberrations. Current welding fume exposure during the week before sampling was not associated with increases in any type of cytogenetic damage. The results indicated that the increase in chromatid breaks was associated with cumulated welding fume exposure for more than a year, and with not using respirators. Exposure to MMA/SS welding fumes for up to 4 months gave a slight, but significant increase in chromatid breaks when using the welders as their own referents. However, when using matched referents in the study after exposure, no difference was found between these welders and their matched referents. No differences between the groups were observed in the DNA synthesis and repair-inhibited cultures or for SCE.

Adult↗
PubMed2005

A comprehensive study on neurobehavior, neurotransmitters and lymphocyte subsets alteration of Chinese manganese welding workers.

The neurotoxicity of manganese has been demonstrated by many researches. But few reports have been found on its immunotoxicity in manganese-exposed workers. Here we selected welding workers (aged 34 years) as Mn-exposed subjects. They have been exposed to manganese for 16 years. The control group was from a flour plant. The average concentrations of Mn, Cd, Fe and Ni in work place were 138.40 +/- 11.60 microg/m3, 581.40 +/- 45.32 microg/m3, 3.84 +/- 0.53 microg/m3 and 12.64 +/- 2.80 ng/m3, respectively. Blood Mn (4.84 mug/dl) of welding workers was higher than that of the control group (1.92 microg/dl). Neurobehavioral core test battery (NCTB) recommended by WHO was conducted on the subjects and found that the scores of negative emotions, such as confusion-bewilderment, depression-dejection, fatigue-inertia, and tension-anxiety, were higher in welding workers. Visual simple reaction time and the fast simple reaction time were shorter than that of the control group. The numbers of digital span, forward digital span, backward digital span and digital symbol decreased in welding workers compared with control group. Monoamine neurotransmitters and their metabolism substances in urine were tested by HPLC-ultraviolet. NE, E, MHPG, HVA, DA, DOPAC and 5-HT in the urine of Mn-exposed group had no significant changes while 5-HIAA in Mn-exposed group had significantly decreased compared with that of the control group. Lymphocyte subsets of the subjects were determined by Flow Cytometer. CD3+ T cell, CD4+CD8- T cell, CD4-CD8+ T cell, CD4+CD45RO- "virgin" lymphocytes, CD4+CD45RO+ "memory" lymphocytes, and CD3-CD19+ B cell had no significant changes compared with the control group. The results showed that long-term exposure to manganese in welding might have adverse effects on mood state, neurobehavior, and peripheral neurotransmitters. However, they had no effects on lymphocyte subsets parameters.

Adult↗
PubMed2006

Effects of repeated welding fumes exposure on the histological structure and mucins of nasal respiratory mucosa in rats.

To investigate the effects of welding fumes on the histological structure and properties of mucins of the nasal respiratory mucosa, Sprague-Dawley rats were exposed to manual metal arc-stainless steel (MMA-SS) welding fumes at a concentration of 56-76 mg/m3 total suspended particulates for 2 h per day in an inhalation chamber for 90 days. Experimental animals were sacrificed at 2 h, 15, 30, 60 and 90 days after exposure. Loss of cilia, desquamation of epithelial cells, mucigenous epithelial cells and destruction of nasal septal glands were observed frequently in the welding fumes-exposed groups. These changes became more severe as the exposure continued. The amount of neutral mucins in goblet cells in the welding fumes-exposed group had a tendency to increase, the amount of sulfomucins decreased, while the sialomucins increased as the exposure continued. Mucinogenic epithelial cells, not visible in the control group, contained minimal to small amounts of neutral mucins. In the dorsal septal glands, neutral mucins not visible in the control group appeared, and neutral mucins in the ventral septal glands increased slightly. These results indicate that the observed changes in the properties of mucins due to inhalation of welding fumes may play roles in protection against toxicants.

Animals↗
PubMed1996

Dural closure with laser tissue welding.

This study investigates the use of tissue-soldering techniques to substitute or reinforce traditional suture closure of dural incisions. Fresh human cadaveric dura was incised and subsequently closed by use of three techniques: (1) conventional interrupted suture with 4-0 silk (n = 25), (2) laser solder reinforced suture closure (n = 25), and (3) laser solder closure alone (n = 25). Anastomosis tensile strength and hydrostatic leak pressures were measured. Dural repair was also performed in 15 live Lewis rats. Dural closure was accomplished with 9-0 Prolene sutures (n = 5), laser-reinforced suture closure (n = 5), and laser solder closure alone (n = 5). Histologic examination of the closure immediately after soldering and 2 weeks later was performed. Suture closure alone had the lowest leak pressure, 9.4 +/- 1.7 mm Hg, and an intermediate break point, 13.3 +/- 2.1 Kgf/cm2. Measurements with laser solder alone revealed a mean leak pressure of 26.2 +/- 3.7 mm Hg and a break point of 4.6 +/- 1.4 Kgf/cm2. Solder-reinforced suture closure leak pressure measured 64.0 +/- 6.7 mm Hg and 21.4 +/- 2.4 Kgf/cm2. There was a statistically significant increase in leak pressure and tensile strength in the closures performed with laser weld reinforcement of traditional suture technique (p = 0.0001). Dural closure with laser tissue welding alone provided an immediate leak-free closure, but with poor tensile strength. Histologic examination of welded dura and underlying brain tissue showed no evidence of thermal injury in four of five animals studied. Laser welding may significantly decrease the incidence of cerebrospinal fluid leak after dural closure. In addition, laser tissue welding also makes dural closure possible where space constraints make traditional suture closure difficult.

Animals↗
PubMed2003

Recovery from manual metal arc-stainless steel welding-fume exposure induced lung fibrosis in Sprague-Dawley rats.

Welders with radiographic pneumoconiosis abnormalities have exhibited a gradual clearing of the X-ray identified effects following removal from exposure. In some cases, the pulmonary fibrosis associated with welding fumes appears in a more severe form in welders. Accordingly, to investigate the disease and recovery process of pneumoconiosis induced by welding-fume exposure, rats were exposed to welding fumes with concentrations of 63.6+/-4.1 mg/m(3) (low dose) and 107.1+/-6.3 mg/m(3) (high dose) of total suspended particulate for 2 h per day in an inhalation chamber for a total of 2 h or 15, 30, 60 or 90 days. Thereafter, the rats were no longer exposed and allowed to recover from the welding fume-induced lung fibrosis for 90 days. When compared to the unexposed control group, the lung weights significantly increased in both the low- and high-dose rats from day 15 to 90. A histopathological examination combined with fibrosis-specific staining revealed that the lungs from the low-dose rats did not exhibit any significant progressive fibrotic changes. Whereas, the lungs from the high-dose rats exhibited early delicate fibrosis from day 15, which progressed into the perivascular and peribronchiolar regions by day 30. Interstitial fibrosis appeared at day 60 and became prominent by day 90, along with the additional appearance of pleural fibrosis. Recovery, evaluated based on the body and lung weights and a histopathological examination, was observed in both the high and low-dose rats that were exposed up to 30 days. The rats exposed for 60-90 days at the low dose also recovered from the fibrosis, yet the rats exposed for 60-90 days at the high dose did not fully recover. Consequently, recovery from pneumoconiosis induced by welding-fume exposure was observed when the degree of exposure was short-term and moderate.

Air Pollutants, Occupational↗
PubMed1998

Freshly generated stainless steel welding fume induces greater lung inflammation in rats as compared to aged fume.

It has been previously reported that both short- and long-lived reactive oxygen species (ROS) are present on the surface of freshly generated fumes. The objective of this study was to determine if freshly formed welding fume induces greater lung inflammation and injury in rats due to the presence of reactive oxygen species than aged welding fume. Fume was collected during gas metal arc welding using a stainless steel consumable electrode and found to be of respirable size with a mean diameter of 0.77 microm +/- 0.48. Male CD/VAF rats were dosed intratracheally with the welding fume 30 min (fresh) and 1 and 7 days (aged) after fume collection at a dose of 1.0 mg/100 g b wt. Bronchoalveolar lavage (BAL) was performed 24 h post-instillation. Lung injury and inflammation were assessed by measuring the concentration of neutrophils, albumin, lactate dehydrogenase (LDH), and glucosaminidase (GLU) in the recovered BAL fluid. More neutrophils and enhanced GLU activity were observed for the 'fresh' group as compared to both 'aged' groups (P < 0.05). Slight, but not significant, elevations were seen in albumin content and LDH activity for the 'fresh' group as compared to the 'aged' groups. No significant differences were observed for any of the parameters when fume aged for 1 and 7 days were compared. When the 'fresh' and 'aged' fumes (12.5, 25, and 50 microg/ml) were suspended in dichlorofluorescin (15 microM), a probe which becomes fluorescent when oxidized, the concentration-dependent increases in fluorescence were greater for the 'fresh' fume versus the 'aged' fumes. We have demonstrated that freshly generated stainless steel welding fume induces greater lung inflammation than 'aged' fume. This is likely due to a higher concentration of ROS on fresh fume surfaces.

Air Pollutants, Occupational↗