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At least 1,423 records · Page 79Linked to original sources
PubMed2002

Ultrasonic shear coagulation of main hilar vessels: A 4-year experience of 23 pediatric laparoscopic splenectomies without staples.

BACKGROUND: Ultrasonic shears (LCS) are used increasingly for laparoscopic splenectomy. So far however, all investigators use vascular staplers or clips for section of the main splenic artery and vein. METHODS: After several trials the authors started to use the ultrasonic triple welding technique in open surgery to occlude major vessels of 5 to 8 mm by 10-mm LCS. In June 1997 the authors introduced triple welding into laparoscopic splenectomy to mobilize the complete spleen by LCS. RESULTS: There was no hemorrhage in 23 laparoscopic splenectomies performed exclusively by LCS and no complications except 1 port site hernia. CONCLUSIONS: Laparoscopic splenectomy entirely by reusable LCS without clips and stapler is a safe, simple, and inexpensive technique. Moreover, the policy of "leaving nothing back" is an attractive strategy in endoscopic pediatric surgery.

Adolescent↗
PubMed2000

łGradation of sideropneumoconiosis.

Pathological-anatomical analyses of biopsy and autopsy samples of 43 men with anamnestically established occupational exposure to welding fumes showed in 38 specimens (88%) characteristic alterations of varying degrees of sidero pneumokonioses. Based on recurrent histological findings of increase and activation of iron storing macrophages (siderophages) and varying degrees of fibrosis, sidero pneumokonioses are classified into three grades. Intraindividually and also toporegionally different degrees may well be present. Based on morphological criteria of the three grades, seven samples were classified as grade I, 21 specimens as grade II, and 10 samples as grade III. The results show that exposure to welding fumes may well cause pulmonary alterations reaching an impairment level, depending on length, extent and special circumstances of the respective exposure. In cases of so-called welders lungs, an obliging statement in an expert's opinion on the degree of functional impairment, however, can only be given when histological findings, detailed information on the occupational history and clinical functional parameters are combined.

Autopsy↗
PubMed2000

Laser-assisted myringoplasty--technical aspects.

At lower power, lasers fuse collagen fibres and weld tissues. Welded collagen fibres make a solid bond and allow tissue growth along the bonded edges. Our aim was to study applicability of lasers in myringoplasty. We used a KTP-532 laser in outpatient myringoplasty. The laser beam was delivered through a micromanipulator connected to a microscope or through a 200-400-micron silica fibre. The perichondrium was used for transplantant and harvested from the tragus. The margins of the perforation in the eardrum were evaporated, with the laser operating in a continuous mode at 2-4 W. The middle ear was filled with gelfilm to provide support for the transplant. The perichondrium was placed under the margins of the tympanic membrane and lazed at low power (0.2-1.5 W) in continuous mode. In pale tissues, venous blood, methylene blue or fluorescein was used to enhance the tissue admittance of laser energy. Surgical failures were linked to thermal tissue damage due to excessive energy during lazing. In two cases, visibility via microscope into the anterior edge was not complete and the transplantant did not adhere in the relatively limited area. One patient had epidermal growth under the tympanic membrane and developed local cholesteatoma. Laser-assisted myringoplasty provides several advantages over traditional myringoplasty: it is minimally invasive, no manipulation of the ossicles is needed and it is convenient in anterior perforations, where it can be done endoscopically. We prefer a fibre delivery system to a micromanipulator, as lazing with endoscopes is possible and thermal damage is easier to prevent.

Cholesteatoma, Middle Ear↗
PubMed1977

Performance of the piezoelectric microbalance respirable aerosol sensor.

A battery-portable respirable aerosol sensor has been experimentally evaluated. Calibration procedures are described. For instruments calibrated with welding smoke, test results show agreement within +/- 15% of parallel filter samples for 10 laboratory and industrial aerosols including welding and tobacco smoke, oil mist, cotton and asbestos mill dusts, powdered metal and walnut shell dusts, and atmospheric urban aerosol in the 0.05-5.5 mg/m3 range. Results show that an average of several piezobalance measurements can accurately simulate a time-integrated filter sample in many industrial environments.

Aerosols↗
PubMed1996

Behaviour, health and integument of four hybrids of laying hens in modified and conventional cages.

1. In 2 trials the health and behaviour of a total of 3552 caged laying hens of 4 hybrids, Dekalb XL, Lohmann Selected Leghorn (LSL) and Shaver 288 in trial 1 and ISA Brown and LSL in trial 2, were studied. The cage designs were Get-away cages (GA) with 15 hens per cage, a special version of the 'Edinburgh modified cage' called 'Modified and enriched cage' (ME) with 4 ISA or 5 Leghorn hens per cage, conventional metal cages with 4 hens per cage without (CO) and with a perch (PC) and conventional plastic cages (PL) with three hens per cage. GA and ME included nests, perches and sandbaths. 2. In the first trial f1p4nest models were used, artificial turf and welded wire floor. In the second trial both nest models were used in GA, while all nests in ME were equipped with artificial turf. In the second trial there were 4 sandbath treatments in ME; no sandbath, sandbath (25 x 50 cm) first opened at 16 weeks of age, sandbath first opened at 26 weeks and double size sandbath (50 x 50 cm) first opened at 16 weeks. Hens in GA were allowed access to the sandbaths from 26 weeks. 3. At 35 and 55 weeks the best plumage condition (feather cover) was found in PL and GA but plumage condition in ME was not significantly inferior than in GA. Hens in GA had the dirtiest plumage and most bumble foot but no toe pad hyperkeratosis. Some toe pad hyperkeratosis occurred in the other systems. Most keel bone lesions were found in systems with perches. The highest mortality was registered in GA. Hens in systems with perches, sandbaths and nests had increased strength of humerus at slaughter. 4. More eggs were laid in nests with artificial turf than in welded wire floor nests. LSL hens laid larger proportions of eggs in the nests (94% and 92% in the two trials) than the other hybrids. Less than 1% of the eggs in ME and 2% in GA were laid in the sandbaths. 5. The use of perches in ME and PC was approximately 30% in the day time. At night the use was 93% in ME and 89% in PC in trial 1 and 96% in ME and 81% in PC in trial 2. 6. Hens in ME with the double sized sandbath both visited the sandbath and performed dust bathing behaviour most, followed by hens in GA, hens in ME with access to the bath from 16 weeks and last, hens in ME with access to the bath from 26 weeks. 7. It is concluded that enrichments of laying cages are used by the hens to a large extent if properly constructed and managed, implying an increased behavioural repertoire of the hens compared with conventional cages. With perches at only one level and with smaller groups of birds, ME provided better hygiene and inspection properties than GA.

Analysis of Variance↗
PubMed1996

A method for measuring the CO2 dead space volume in facial visors and respiratory protective devices in human subjects.

The external CO2 dead space volume (Vd) in facial visors and respiratory protective devices is difficult, but important, to measure in human subjects. The lack of proper methods for its assessment has hampered the development of standards and the improvement of visor and device design. We have improved and evaluated a method for measuring Vd and the mean inspired fraction of CO2 (FI,CO2) in human subjects wearing facial visors or respiratory protective devices. The method is based on indirect measurements of inspiratory volumes using a calibrated respiratory inductive plethysmograph (RIP), and measurements of FCO2 with a mass spectrometer. The accuracy of the RIP method was assessed in eight subjects and its repeatability was studied during nasal and oral breathing, at rest and after bicycle ergometer work. We related the Vd,RIP results to two known external VdS (with the effective Vd equal to the geometric volume; 15 ml and 320 ml), through which the subjects breathed, using RIP and a pneumotachometer (PTM) simultaneously (Vd,RIP and Vd,PTM). The repeatability of Vd and mean FI,CO2 results was determined from duplicate recordings during the wearing of a welding visor. Initial RIP calibration was accepted if the inspiratory tidal volume error was < or = 10%. This resulted in an acceptable Vd,RIP error (< or = 20%; Vd = 320 ml) in six eight subjects. The validation technique allowed us to separate the Vd,RIP error into a volumetric error and an error related to CO2 measurement. Poor RIP volumetric accuracy over the initial portion of inspiration was detrimental to Vd accuracy. Using the welding visor, Vd and mean FI,CO2 were less at rest than after work and less during nasal breathing than during oral breathing. The intra-individual variability of Vd and mean FI,CO2 were lower during nasal breathing than during oral breathing. To summarize, the improved RIP based method can accurately (< or = 20% error) assess Vd and mean FI,CO2 in facial visors and respiratory protective devices in standardized work situations. A meticulous RIP calibration procedure and repeated validations of RIP volume and CO2 measurement accuracy must, however, be applied.

Adolescent↗
PubMed2003

Development of a continuous aerosol mass concentration measurement device.

A dynamic aerosol mass concentration measurement device has been developed for personal sampling. Its principle consists in sampling the aerosol on a filter and monitoring the change of pressure drop over time (Delta P). Ensuring that the linearity of the Delta P = f(mass of particles per unit area of filter) relationship has been well established, the change of concentration can be deduced. The response of the system was validated in the laboratory with a 3.5 microm alumina aerosol (mass median diameter) generated inside a 1-m(3) ventilated enclosure. As the theory predicted that the mass sensitivity of the system would vary inversely with the square of the particle diameter, only sufficiently fine aerosols were able to be measured. The system was tested in the field in a mechanical workshop in the vicinity of an arc-welding station. The aerosol produced by welding is indeed particularly well-adapted due to the sub-micronic size of the particles. The device developed, despite this limitation, has numerous advantages over other techniques: robustness, compactness, reliability of calibration, and ease of use.

Aerosols↗
PubMed2003

Impact of coexposure to ozone on the carcinogenic potential of inhaled chromium. 1. effects on retention and on extra- and intracellular distribution.

A health hazard to welders is development of lung cancer. It is believed that this is likely due, in part, to the presence in welding fumes of several hexavalent chromium (Cr[VI]) species, whose solubility depends primarily on which process (i.e., manual metal arc verus metal-inert gas) is used. However, inhalation of Cr alone is uncommon in this setting. Thus, an examination of potential contributions from other coinhalants in creating or enhancing conditions whereby inhaled fume-associated Cr (primarily the insoluble forms) may initiate cancer is critical to increasing our understanding and preventing this particular occupational disease. One major chemical species formed and released during welding is ozone (O3). Though implications of adverse pulmonary effects from individual exposure to Cr or O3 have been investigated, those from simultaneous exposure are unclear. To begin to address whether the carcinogenic potential of insoluble Cr[VI] agents might be enhanced in hosts inhaling mixtures of Cr and O3 versus Cr alone, analyses of total lung Cr burden, Cr retention in lung epithelium and interstitium, and potential shifts in lung cell distribution of Cr from the cytoplasm to nuclei were undertaken in F-344 rats exposed nose-only (5 h/d, 5 d/wk for up to 48 wk) to an extrapolated occupationally relevant level of Cr (360 micrograms Cr/m3 as calcium chromate) alone and in combination with 0.3 ppm O3. Overall, there was only a nominal effect from O3 on Cr retention or on distribution of Cr particles among extracellular sites and within lung cells. However, there were O3-related effects upon mechanisms for clearing the Cr from the deep lung, specifically at the levels of particle uptake and postphagocytic/endocytic processing by macrophages. This O3 exposure-related shift in normal pulmonary clearance might potentially increase the health risk in workers exposed to other insoluble or poorly soluble carcinogenic Cr compounds.

Administration, Inhalation↗
PubMed1990

Laser vascular tissue fusion: development, current status, and future perspectives.

Tissue fusion has a number of vascular applications such as making sutureless blood vessel anastomoses and for securing the end points of endarterectomies and dissection planes. Precision of tissue apposition at the time of fusion has been found to be a critical parameter, affecting the rate of healing and tensile strength of tissue welds. Several laser wavelengths can be used to accomplish vascular and other soft tissue fusions. Potential advantages of laser fusion over suture techniques may include healing without foreign body reaction related to sutures and preserved mechanical properties at anastomoses. While preliminary experimental and clinical data are very promising, additional work is needed. This would include determining the mechanism and optimal laser parameters and wavelengths required for vascular tissue fusion. In addition, the characteristics needed to seal uniformly large-diameter arteries and to fashion welds that withstand systemic arterial pressures must be identified. Follow-ups of approximately three years suggest that strong initial primary seals will eliminate significant adverse effects.

Adult↗
PubMed1999

A new instrument for hemostatic vascular management in endoscopic surgery: diode laser (STATLase-SDL) and its handpiece (dual hook).

OBJECTIVE: The authors described experimental data in hemostatic vascular transection using a STATLase-SDL with a 780-865 nm GaA/As diode wavelength and its handpiece, Dual Hook (DH). SUMMARY BACKGROUND DATA: The STATLase-SDL and DH are newly developed devices for endoscopic surgery. It seems that the device has improved hemostatic cutting ability. METHODS: The DH was applied to the abdominal aorta (< 2 mm) of Japanese white rabbits (n = 15) under general anesthesia. Tissue temperature during laser transection and interluminal bursting pressures were measured. Histopathological examinations at the cut end were carried out by hematoxylin-eosin (H&E) and elastica Van Gleson's (EVG) stainings. To investigate short-term effects 11 days postoperatively, the cut ends of the vessels were examined histologically in the heminephrectomy group. RESULTS: The DH hemostatistically cut through arteries up to 2 mm in diameter. Temperatures at the inner hook and in adjunct tissue were higher than 160 degrees C, while that at the outer hook was lower than 80 degrees C. The bursting pressures immediately after transection was 307.2 +/- 35.2 mm Hg at a laser power of 8 W (n = 5), and 295.6 +/- 28.7 mm Hg at 10 W (n = 5). Histological examination of the transected sites on the vessels revealed well-opposed tissue welding of the vascular wall. Absence of fragmentation in the welding of the internal elastic lamina is crucial for closure of the vessel stump. Up to 11 days postoperatively, there were no direct complications related to the use of the DH. CONCLUSIONS: The STATLase-SDL and DH have good hemostatic cutting ability and might be suitable for endoscopic surgery.

Angioscopes↗
PubMed1995

Nephron-sparing laparoscopic surgery: techniques to control the renal pedicle and manage parenchymal bleeding.

Laparoscopic nephron-sparing surgery has been limited by several factors, including problems in the control of the vascular pedicle and the management of parenchymal bleeding. In an effort to improve the efficacy of laparoscopic nephron-sparing surgery, we developed and tested several techniques to control and manage intraoperative renal bleeding while performing 30 laparoscopic anatrophic nephrolithotomies using the porcine model. Control of the renal pedicle and management of bleeding included the use of the following: (1) extracorporeally applied atraumatic vascular pedicle clamp; (2) Argon Beam Coagulator to perform the capsulotomy; (3) electrocautery scissors to perform the nephrotomy; (4) Gelfoam welded to the cut surface of the parenchyma with the argon beam coagulator; (5) Surgicel welded to the outer surface of the kidney with the Coagulator; and (6) laparoscopically applied bolster sutures to further stabilize the renal unit. All animals tolerated the procedure well and survived to their appointed date of sacrifice. We conclude that these techniques may improve the efficacy of laparoscopic renal surgery, including nephron-sparing procedures.

Animals↗
PubMed2002

Molecular epidemiology of VHL gene mutations in renal cell carcinoma patients: relation to dietary and other factors.

Carcinogenic chemicals act through DNA damage and mitogenic effects. No established mechanism explains the cancer preventive effects, if any, of food items, such as vegetables and fruit. If such data were available, preferably on tumor-initiating genes, the evidence for the protective effects would become stronger. The von Hipple-Lindau (VHL) gene is the tumor suppressor gene predisposing to both sporadic renal cell carcinoma (RCC) and von Hippel-Lindau disease. We have earlier analyzed VHL mutations in RCCs from 102 Swedish patients identified in a case-control study and here examine associations between patient characteristics, including dietary habits and mutations, considering the type of mutation. The results are given as odds ratios (OR), separately for smokers and all patients. In univariate analysis, consumption of vegetables and citrus fruit decreased the frequency of VHL mutations among smokers and citrus fruit among all patients. In multivariate analysis of smokers' characteristics, welding fumes showed a risk of 5.63 for multiple VHL mutations. In smokers, citrus fruit decreased the OR of GC to AT mutations to 0.13 and that of multiple mutations to 0.17; vegetables decreased the OR for single mutations to 0.22. Among all subjects, welding fumes were a risk factor and citrus fruit a protective factor. Additionally, an intake of selenium protected against multiple mutations. The present results provide evidence that the intake of vegetables, selenium and particularly of citrus fruit protects the renal VHL gene from mutational insults that may be endogenous or common in a population. Even though most of the associations are biologically plausible, and vegetables and fruit were an a priori hypothesis, fortuitous results cannot be ruled out in this relatively small study.

Adult↗
PubMed2006

The influence of occupational exposure on male reproductive function.

Recently, many studies have found a decrease in semen quality which has increased the focus on male reproductive health. Occupational hazards are by far the best documented in reproductive epidemiological research. Generally, occupational exposures have been divided into physical exposures (heat and radiation), chemical exposures (solvents and pesticides), psychological exposures (distress), exposure to metals and welding. The recent and/or most important epidemiological studies exploring the effect of occupational exposures on semen quality and fecundity, the ability to conceive, are reviewed. The evidence for an adverse effect on male reproduction of several occupational and environmental exposures and toxicants, such as heat, ionizing radiation, inorganic lead, dibromochloropropane, ethylene dibromide, some ethylene glycol ethers, carbon disulfide and welding operations, is strongly supported in well-designed epidemiological studies. For other agents, the association is only suspected or suggested and needs further evaluation before conclusions can be drawn. It is also important to bear in mind that many workers in the non-Western world still are exposed to substances that are banned in the Western world, sometimes in high concentrations.

Fertilization↗
PubMed2005

Immediate replacement removable partial dentures with cobalt-chromium frameworks: rationale, technology and a case report.

The advantages of removable partial dentures with cobalt-chromium frameworks over those made entirely of acrylic resin, in oral health and hygiene, are well documented. However, in cases where teeth are to be extracted for fitting the removable partial denture, a difficulty arises because of the need to test the fit of the removable partial denture framework. The advent of two modern technologies-- laser welding and metal bonding agents -- make it possible to test the fit of the major part of the framework prior to adding additional metal components to support artificial teeth. A case is described in which the four lower incisors were extracted. The main part of the framework was constructed and its fit tested. A second casting was laser-welded to the lingual plate of the first casting to support the artificial incisor teeth. This technique avoids the need to make an acrylic resin temporary denture but incurs the cost of the additional technical work and so the advantages may be considered to be economically neutral.

Adult↗
PubMed2006

Syncrystallization: a technique for temporization of immediately loaded implants with metal-reinforced acrylic resin restorations.

BACKGROUND: Rigid temporization has been recognized to have a significant impact on the peri-implant tissue response in immediate implant loading since it reduces the mechanical stress exerted on each implant. PURPOSE: A successful protocol for immediate loading of multiple implants depends on an adequate fixation and immobility of the implants to prevent the risk of micromovements in relation to the surrounding bone. The objective of this article was to evaluate a prosthetic concept for an accelerated rigid splinting of multiple implants for same-day immediate loading with metal-reinforced provisional restorations using a technique of welding temporary implant abutments with a prefabricated titanium bar directly in the oral cavity (syncrystallization). MATERIALS AND METHODS: Between June 2004 and January 2005, immediate loading of threaded implants with a metal- reinforced acrylic resin provisional restoration at stage 1 surgery was evaluated in 40 consecutive patients. A total of 192 implants were placed in selected edentulous or partially edentulous patients using the syncrystallization technique. Once the titanium bar was welded intraorally to the abutments, opaque was applied and the provisional restoration was relined and screw-retained the same day. In addition, a comparison of deformations and stress distributions in implant-supported, metal-reinforced and nonmetal-reinforced resin provisional restorations was analyzed in the edentulous mandible by a three-dimensional finite element model (FEM). RESULTS: All of the 192 rigidly temporized immediately loaded implants osseointegrated. An implant success rate of 100% was achieved over a period of 6 months postplacement. No fracture or luting cement failure of the provisional restoration occurred during the observation time. Compared to mere acrylic superstructures, a significant reduction of deformation and strain within metal-reinforced provisional restorations was detected by FEM analysis. CONCLUSION: The results of this study indicate that the syncrystallization technique allows an expedite and adequate rigid splinting of multiple immediately loaded implants. The advantages of the technique are: (1) reduction of treatment time for immediate temporization at stage 1 surgery; (2) predictable fixation and immobility of implants in the early stages of bone healing; and (3) less time for repairing provisional restorations as a result of no or rare fracture.

Acrylic Resins↗
PubMed2002

Dosimetric characteristics of the DRAXIMAGE model LS-1 1-125 interstitial brachytherapy source design: a Monte Carlo investigation.

(Received 5 June 2001; accepted for publication 26 December 2001; published 19 March 2002) We have used Monte Carlo photon transport simulations to evaluate dosimetric characteristics of a new 125I seed, the DRAXIMAGE BrachySeed (model LS-1) source for interstitial brachytherapy and to calculate the dosimetric parameters recommended by the AAPM Task Group 43 (TG-43). To eliminate thick end welds, preformed closed-ended Ti shells are welded together near the transverse plane. The radioactivity is localized near the seed ends in order to maximize isotropy at typical prescription distances. Transmission radiography reveals that its internal components can move by as much as 200 microm under the influence of gravitational forces affecting the dose-rate constant and relative dose distribution by as much as 5% and 10%, respectively. However, the clinical dose distribution can be well represented by a weighted average of dose distributions corresponding to three different orientation-dependent internal geometry configurations. This average dose distribution agrees closely (within 1% at 1 cm) with that derived from the geometry specified by the vendor model (seed components uniformly spaced), from which the recommended relative dosimetry parameters were derived. An average dose-rate constant of 0.935 cGy h(-1) U(-1) is recommended for clinical application and values of 0.919, 0.963, and 0.920 for vertical orientation, horizontal orientation, and the vendor specified geometries, respectively. The NIST wide-angle free-air chamber realization of the air-kerma strength primary standard, SKN99, was explicitly simulated. We show that the output of Ag characteristic x rays is about half that of the model 6711 source resulting in a relative dose distribution between that of the model 6711 source and pure 125I x-ray emitters. Finally, it is demonstrated that the TG-43 point-source formalism more accurately estimates solid-angle weighted dose at small distances if one uses a radial dose function data prepared using a point-source, rather than line-source, geometry factor.

Air↗
PubMed1989

Manganese induced parkinsonism: an outbreak due to an unrepaired ventilation control system in a ferromanganese smelter.

Several cases of parkinsonism were found in a ferromanganese smelter after the ventilation system had broken down and had not been repaired for eight months in 1985. To determine the aetiology and prevalence of parkinsonism, 132 workers were submitted to thorough medical examination and estimated air concentrations of carbon monoxide and manganese at different worksites. Only six of eight workers performing electrode fixation or welding during 1985 developed parkinsonism. They were exposed for 30 minutes each day, seven days a week, to high concentrations of air manganese (greater than 28.8 mg/m3). There was a consistent trend between the index of exposure to manganese and signs and symptoms exhibited by extrapyramidal systems. After repair of the ventilation system, the air concentration of manganese during electrode fixation and welding decreased to less than 4.4 mg/m3; furthermore, no new cases of parkinsonism have been observed. Workers with parkinsonism recovered partially after removal from original worksites and treatment with levodopa. It is concluded that the outbreak resulted from exposure to high concentrations of manganese fumes through the breakdown of the ventilation system.

Adult↗