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At least 1,459 records · Page 81Linked to original sources
PubMed1999

Adult-onset asthma and occupational exposures.

OBJECTIVES: This study examined certain occupational exposures and the risk for adult-onset asthma. METHODS: A nested case-referent study of adult-onset asthma was performed on a random population sample (N=15813), aged 21 to 51 years. Cases for the study included 2 groups: subjects reporting "physician-diagnosed" asthma (N=251) and a broader "asthma" group (N=362). The "asthma" group consisted of subjects with "physician-diagnosed" asthma (N=251) and subjects reporting asthma-like symptoms without having "physician-diagnosed" asthma (N=111). The referents (N=2044) were randomly selected from the whole population sample. The case-referent sample was investigated with a comprehensive questionnaire about occupational exposures, asthma, respiratory symptoms, smoking, and atopy. Odds ratios were calculated with stratification for gender, year of diagnosis, and birth year. RESULTS: The highest odds ratio for "physician-diagnosed" asthma was associated with exposure to flour dust [odds ratio (OR) 2.8, 95% confidence interval (95% CI) 1.5-5.2] and the occupational handling of resin-based paints (isocyanates) (OR 3.0, 95% CI 1.6-5.9). Exposure to welding fumes, textile dust, and work with glues containing acrylates was also associated with an increased odds ratio for "physician-diagnosed" asthma. Including persons with asthma-like symptoms (ie, the asthma group) showed similar results. CONCLUSION: This population-based case-referent study from Sweden indicates that occupational exposure to acrylate-based compounds and welding fumes is associated with increased risk for adult-onset asthma.

Adult↗
PubMed1992

UV curing adhesives for medical device assembly.

UV cured medical-grade aerobic adhesives yield the same structural bond strength as thermal, sonic, or solvent welding. Solvents are recognized as having a potential for negative health and environmental effects. Substrate limitations have historically restricted medical device design when using sonic or thermal welding techniques. UV curing aerobic adhesives clearly represent a significant advance for an industry in which product reliability and user safety are a requisite.

Acrylic Resins↗
PubMed1999

Photodynamic tissue adhesion with chlorin(e6) protein conjugates.

PURPOSE: To test the hypothesis that a photodynamic laser-activated tissue solder would perform better in sealing scleral incisions when the photosensitizer was covalently linked to the protein than when it was noncovalently mixed. METHODS: Conjugates and mixtures were prepared between the photosensitizer chlorin(e6) and various proteins (albumin, fibrinogen, and gelatin) in different ratios and used to weld penetrating scleral incisions made in human cadaveric eyes. A blue-green (488-514 nm) argon laser activated the adhesive, and the strength of the closure was measured by increasing the intraocular pressure until the wound showed leakage. RESULTS: Both covalent conjugates and noncovalent mixtures showed a light dose-dependent increase in leaking pressure. A preparation of albumin chlorin(e6) conjugate with additional albumin added (2.5 protein to chlorin(e6) molar ratio) showed significantly higher weld strength than other protein conjugates and mixtures. CONCLUSIONS: This is the first report of dye-protein conjugates as tissue solders. These conjugates may have applications in ophthalmology.

Chlorophyllides↗
PubMed2000

CO2 and Nd:YAG laser-assisted nerve repair: a study of bonding strength and thermal damage.

To improve the laser welding procedure, a comparative study was undertaken to investigate the acute bonding strength and the thermal damage following CO2 and Nd:YAG laser-assisted nerve repair, performed with and without the use of blood and/or albumin as a solder. The strongest welds were produced with the CO2 laser using albumin as a solder. Thermal damage was minimal with the CO2 laser, whereas the damage with the Nd:YAG laser was substantial. The high bonding strength combined with minimal thermal damage of the nerve following repair with the CO2 laser with the use of albumin justify further investigations using this technique in in vivo studies.

Animals↗
PubMed2000

Clinical trials of Chitra band material.

Stainless steel band material was developed and tested for physico-chemical mechanical toxicological and in-vitro evaluation in dogs, at the Sree Chitra Thirunal Medical Institute, Trivandrum. Weld strength and tensile strength were measured with the Instron testing machine. A clinical pilot study was conducted at College of Dental Surgery, Manipal on 150 patients earlier. In the present study, Chitra bands were cemented on upper and lower molars on one side and Dentaurum bands on the other side, as controls in the same patient. The band was allocated to right and left molars at random. The study was a double blind trial. Thus fifty cases had Chitra bands on the left side and fifty on the tight side. Hundred cases were treated with fixed appliance treatment. The age, sex and technique of treatment were recorded. The spot welder and the cement used were also noted. The patients were recalled every month for nine months and the findings entered in the initial and follow-up proforma by another Orthodontist, making it a blind study. Loose bands, broken bands, broken tubes, broken welds, plaque accumulation, gingival bleeding and gingivitis were noted. The findings will be presented and the clinical applicability of Chitra Band Material discussed.

Animals↗
PubMed2001

Standard anatomical medullary locking (AML) versus tricalcium phosphate-coated AML femoral prostheses.

OBJECTIVES: To compare the preliminary rate and amount of bony ingrowth and calcar resorption between patients receiving either a standard anatomical medullary locking (AML) or a tricalcium phosphate (TCP)-coated AML femoral prosthesis and to compare preliminary clinical results. DESIGN: A prospective, randomized, double-blind clinical trial. SETTING: An acute care tertiary institution. PATIENTS: Between January 1993 and March 1995, 92 patients underwent primary total hip arthroplasty (THA). They were randomized to 2 groups of 46--a control group or a treatment group. Of the 46 subjects enrolled in each group, no significant differences were seen preoperatively with respect to age, sex, diagnosis, clinical and radiographic assessment. Seventy-one patients were followed up for 24 months. INTERVENTIONS: Insertion of either a standard AML femoral implant (control group) or a TCP-coated AML femoral implant (treatment group). OUTCOME MEASURES: The degree of hypertrophy, calcar atrophy and the number of spot welds on standard postoperative radiographs at 6, 12 and 24 months. Clinically, assessment according to the Société internationale de chirurgie orthopédique et de traumatologie (SICOT) scale and a 100-point visual analogue scale (VAS) for pain. RESULTS: There were no prosthetic stem revisions in either group at the 24-month follow-up. Radiographically, bony ingrowth was not significantly different in the TCP-coated stem, by chi2 analysis of the degree of hypertrophy and number of spot welds present. Also by chi2 analysis, the degree of calcar atrophy was not significantly different between groups. The mean VAS score for pain at 24 months was 12.5 for the control and 12.1 for the treatment group. No significant differences were seen in any of the clinical categories of the SICOT Scale over the 24-month interval. CONCLUSION: The objective of TCP-coating--to increase the rate and amount of bony ingrowth while reducing the rate of calcar resorption in non-cemented THA--was not achieved by 24 months postoperatively in our study.

Arthroplasty, Replacement, Hip↗
PubMed2001

[Lasers in dentistry. Part B--Interaction with biological tissues and the effect on the soft tissues of the oral cavity, the hard tissues of the tooth and the dental pulp].

The interaction of laser energy with target tissue is mainly determined by two non operator-dependent factors: the specific wavelength of the laser and the optical properties of the target tissues. Power density, energy density, pulse repetition rate, pulse duration and the mode of energy transferring to the tissue are dictated by the clinician. Combination of these factors enables to control optimal response for the clinical application. Four responses are described when the laser beam hits the target tissue: reflection, absorption, transmission and scattering. Three main mechanisms of interaction between the laser and the biological tissues exist: photothermic, photoacoustic and photochemical. The effect of lasers on the soft tissues of the oral cavity is based on transformation of light energy into thermal energy which, in turn heats the target tissue to produce the desirable effect. In comparison to the scalpel used in surgical procedures, the laser beam is characterized by tissue natural sterility and by minimum bleeding during the surgical procedures due to blood vessels welding. The various effects achieved by the temperature elevation during the laser application on the soft tissue are: I. coagulation and hemostasis II. tissue sterilization III. tissue welding IV. incision and excision V. ablation and vaporization Ablation and melting are the two basic modalities by which the effect of lasers on the hard tissues of the tooth is produced. When discussing the effect of laser on dental hard tissues, the energy absorption in the hydroxyapatite plays a major role in addition to its absorption in water. When laser energy is absorbed in the water of the hard tissues, a rapid volume expansion of the evaporating water occurs as a result of a substantial temperature elevation in the interaction site. Microexplosions are produced causing hard tissue disintegration. If pulp temperatures are raised beyond 5 degrees C level, damage to the dental pulp is irreversible. Histologically, after laser ablation, presence of odontoblastic nuclei is important. Consistency and composition of the intracellular tissue is another factor influencing cell viability. If heat is intensive and exists for an extended time, the consistency of the intracellular ground substance may not be preserved. Accordingly, the application of excessive energy densities has been shown to result in significant damage to pulp tissue and in particular to odontoblasts. Studies showed that the use of Er:YAG laser to treat dental hard tissues is both safe and effective for caries removal, cavity preparation and enamel etching.

Absorption↗
PubMed1992

Laser hepatorrhaphy in albino rats.

The ability of low-power Nd-YAG laser to weld liver tears was studied in nine albino rats (average body weight 146 g) after induction of 11 liver tears. Laser hepatorrhaphy was successful in ten tears. Haemostasis was achieved with the laser technique in all 11 tears, including the single case of postoperative liver tear dehiscence. Bleeding from the site of a marker stitch was successfully controlled by two additional laser shots in one animal. Histologic studies of successfully welded liver tears were done on the first and third postoperative days.

Animals↗
PubMedDate not supplied

[Return to work of a pacemaker bearing worker: the relationship between health problems and electromagnetic interferences].

The potential effects of electromagnetic fields is a problem that interest the public opinion, as the modern society expose all people to electromagnetic non ionizing radiations. The problem has a particular and important meaning facing the return to normal life and work conditions of a cardiopatic subject bearing a pacemaker (PM) or implantable cardioverter defibrillator (ICD). Electromagnetic interferences can produce temporary or permanent malfunctions in these devices. Checking for the absence of electromagnetic interferences is necessary considering that correct functioning of these medical devices is essential for the life of the bearer. Precautions normally adopted by these subjects are generally adequate to ensure protection from interferences present in life environment; for occupational environment, there is often lack of adequate information, also due to late involving of the doctor specialist in occupational health. This work intends to study in depth a specific job, a carpentry-workshop with welding activities, starting with a case of a PM bearer who asked a doctor specialist in occupational health to evaluate the problems involved in his return to work. Electric and magnetic fields produced by equipments present in the workshop were measured and compared to data supplied by the literature to evaluate the possibility of interactions in the normally functioning of implanted electronic devices. On the basis of our experience, we have found some criterions for specific risk assessement to adopt for the definition of operative protocols for return to work of PM or ICD carriers, also considering the lack of specific procedures and indications for the doctor specialist in occupational health. The collected information and data from the literature suggest that welding can be a risk for a subject with PM; as observed in experimental conditions, electromagnetic radiations can alter particular sensitive devices and those with uncorrected settings.

Electromagnetic Fields↗
PubMed2005

On titanium frameworks and alternative impression techniques in implant dentistry.

PURPOSE: The objectives of this thesis were to compare the clinical and material performance of implant-supported titanium frameworks with gold-alloy frameworks in the edentulous jaw and to test a digitized impression technique to optimize material characteristics and clinical and laboratory procedures. MATERIALS AND METHODS: Two different kinds of laser-welded titanium frameworks and one type of digitized computer numeric controlled (CNC)-milled titanium framework for the edentulous jaw were evaluated and compared with gold-alloy frameworks in two clinical 5-year follow-up studies. The CNC frameworks were also evaluated and compared with gold-alloy frameworks in two experimental studies according to fit, preload, and surface roughness. Furthermore, a digitized photogrammetric technique for recording implant positions in the edentulous jaw was experimentally tested and compared with two conventional impression techniques. RESULTS: Laser-welded titanium frameworks had a lower success rate after 5 years in function than gold-alloy frameworks. The 5-year performance of CNC frameworks was similar to that of gold-alloy frameworks. The fit and precision of implant-supported CNC frameworks was significantly better compared with gold-alloy frameworks. Applications of veneering material did not significantly affect the fit of the titanium frameworks. The preload of CNC frameworks was similar to that of gold-alloy frameworks, both exhibiting significantly decreased preloads after repeated tightening. The preloads of titanium frameworks were similar before and after veneering. Unloaded milled titanium screw sites had significantly rougher surfaces than loaded sites, and loaded gold screws had rougher surfaces than unloaded. No correlation between surface of the screw joints and preload of veneered titanium frameworks was observed. The precision of photogrammetric impressions was comparable to that of conventional impression techniques. CONCLUSIONS: Implant-supported CNC-milled titanium frameworks are a viable alternative to gold-alloy castings in the edentulous jaw, and because a digital platform is used to manufacture these titanium frameworks, photogrammetric impressions can be made.

Adult↗
PubMed2005

Effects of coupling methods on galvanic corrosion behavior of commercially pure titanium with dental precious alloys.

BACKGROUND: When a dissimilar couple is exposed to corrosive environment, it will normally exhibit a galvanic corrosion. The galvanic corrosion might be influenced by various factors, including type and concentration of electrolyte, surface area ratio between anode and cathode, type of coupling material, and coupling manner. PURPOSE: The purpose of this study was to investigate and compare the galvanic corrosion behavior of commercially pure titanium when coupled with type IV Au alloy, Au-Ag-Pt alloy, and Ag-Au-Pd alloy by different coupling methods. MATERIALS AND METHODS: Couples were prepared by a laser welding or a mechanical adhering method. Electrochemical corrosion studies were conducted in a Ringer's solution at a scanning rate of 0.1 mV/sec in a range from -250 mV to +250 mV with respect to E(OCP). Corrosion parameters (E(OCP), I(CORR), E(CORR)) were obtained. RESULTS: It was found that (i) there was a significant difference between LWC and AJC for three couples (p<0.05), (ii) the crevice line caused all three couples more corrosive than weld joint line, (iii) for both joint, it was found that type (IV) Au alloy exhibited discoloration to some extent. CONCLUSIONS: It is concluded that among the three couples with two different coupling methods, Ti/Ag-Au-Pd couple exhibited best corrosion resistance in a room temperature Ringer's solution.

Corrosion↗
PubMed2005

Relationship between occupational risk factors and severity markers of systemic sclerosis.

OBJECTIVE: To investigate a potential association between occupational risk factors and severity markers of systemic sclerosis (SSc) defined by diffuse cutaneous extent, pulmonary involvement, and immunologic profile, i.e., presence of antitopoisomerase I antibody (anti-topo I). METHODS: Occupational exposures were assessed in 105 patients with SSc from 1998 to 2002. Exposures to silica dust, welding fumes, solvents, and epoxy resins were investigated. A group of 39 exposed SSc patients and a group of 66 unexposed ones were identified and compared according to severity markers of SSc. The stage of cutaneous extent was defined according to the classification of Leroy, as limited scleroderma (lSSc) or diffuse scleroderma (dSSc). Respiratory status was defined by pulmonary function tests and high resolution computed tomography. Immunological profile was determined by the presence of anti-topo I or anticentromere antibodies (ACA). Statistical relationships between occupational exposures and severity markers of SSc were evaluated using a multiple correspondence analysis and Fisher's exact test. RESULTS: Diffuse scleroderma affected mainly patients exposed during their occupational life to toxic agents. There were significant or close to significant associations between toxic exposure and dSSc (p = 0.06), pulmonary involvement (p = 0.10), and negative ACA (p = 0.03). The most incriminated products seemed to be epoxy resins (p = 0.06), white spirit (p = 0.07), aromatic solvents (p = 0.07), and silica coupled to welding fumes (p = 0.10). CONCLUSION: Our results indicate that occupational toxic factors have an influence on the severity of SSc.

Adult↗
PubMed2006

Argon plasma coagulation and the future applications for dual-mode endoscopic probes.

Argon plasma coagulation (APC) is a thermoablative technique increasingly being used in endoscopy. Since its introduction, the flexible APC probe has been employed by endoscopists throughout the world. APC has helped change the endoscopic management of many gastrointestinal (GI) diseases, including hemorrhagic proctitis, watermelon stomach, bleeding peptic ulcer, and colonic varices. Endoscopists and surgeons are creatively combining standard and new electrosurgical techniques with APC. For instance, APC used in combination with piecemeal polypectomy, endoscopic mucosal resection, balloon dilatation for strictures, and plasma welding of bleeding vessels after sclerotherapy injection are among the recent innovative techniques reported. Other emerging innovations using APC that are being considered include endoscopic en bloc resection of mucosal and submucosal tumors of the GI tract, endoscopic mucosal resection supplemented with APC for high-grade dysplasia and early GI cancers, endoscopic repair of anastomotic strictures, and welding GI fistula tracts. As such, endoscopists require more efficient and cost-effective multifunctional thermoablative probes. This review discusses the development and the potential application of dual-mode plasma endoscopic probes in fulfilling these emerging needs.

Argon↗
PubMed1990

Laser balloon angioplasty: potential clinical applications.

Coronary laser balloon angioplasty (LBA) is a new technique which permits application of heat (generated by the laser source) and pressure (by balloon inflation) to thermally weld tissue during coronary angioplasty (PTCA). The goal of LBA is to achieve a large, smooth arterial lumen, by thermal welding of dissection flaps, elimination of elastic recoil, elimination of vasospasm, reduction in platelet activation, desiccation of thrombus, and inhibition of smooth muscle cell proliferation (Table 1). The LBA system consists of a 50 watt continuous wave Nd:YAG laser with a wavelength of 1060 nm, and a modified coronary balloon angioplasty catheter with a 4.3 French shaft and a PET balloon measuring 20 mm in length and 2.5, 3.0 and 3.5 mm in diameter. For clinical use, laser doses ranging from 250 to 450 joules each are delivered over 20 seconds, to achieve adventitial tissue temperatures of 90 to 110 degrees C. The LBA technique is quite similar to that of conventional PTCA. The LBA catheter is usually positioned over a 0.014" guidewire through an 8 French guiding catheter. Once the laser balloon is in position, the balloon is inflated to a pressure of 4 atmospheres and the programmed laser dose is delivered over 20 seconds, followed by continued balloon inflation for an additional 20 to 40 seconds while the temperature of the arterial wall returns to normal. Conventional PTCA is virtually never necessary to improve lumen appearance and dimensions after LBA. LBA has been shown to be effective in the management of acute failure of PTCA, due to abrupt closure or severe dissection with impaired flow ("impending closure").(ABSTRACT TRUNCATED AT 250 WORDS)

Aneurysm↗
PubMedDate not supplied

Laser fusion of selected dental casting alloys.

Laser-fused precious, nonprecious, and mixed metal welds were investigated for optimum weld energy requirement as determined by tensile strength tests. These strengths were compared to soldered unions. Laser fusion is as good as, or better than, unions created by conventional dental joining methods.

Analysis of Variance↗
PubMed1989

[The work environment and male reproduction].

This review is focused on the connection between environmental factors in the workplace and male reproduction. Infertility is a problem for 10-15 per cent of Danish couples, and little is known about how large a part is played by environmental factors. It is now accepted that exposure by environmental hazards may result in partial or total infertility. The classic examples are exposure to lead, heat and radioactivity. Recent investigations have shown that occupational exposure to chemical substances such as dibromochloropropane and ethylene dibromide may interfere with spermiogenesis. In Denmark studies have been initiated concerning the connection between welding, lead and organic solvents, and the sperm-specimens. The findings of these studies support the hypothesis that, at levels currently accepted at workplaces, lead interferes especially with the sperm-cell concentration. In a few studies exposure to welding fumes have been found to have an adverse effect on sperm cell concentrations. All the investigations cited are marred by methodological problems. Despite these problems, it is internationally recognised that further studies are urgently needed, as are further epidemiological and methodological investigations in this field.

Environmental Exposure↗
PubMed1987

High hydrostatic pressure potentiation of the toxic effects of chromate in cell culture.

Development of hyperbaric welding has created the need for new occupational health standards. We have used cell cultures to investigate effects of high pressure chromate on the toxicity of the welding-fume component, chromate. The results indicate that pressure caused rounding-up of cells and changes in F-actin filaments, and that these effects were related to the extent of high pressure and independent of exposure duration. When exposing the Flow 5000 cells to chromate (1-5 microM) the amount of disrupted F-actin fibers was found to depend on the concentration applied and the duration of exposure. The amount of cell-associated chromate was the same for 1 h exposure at 1 and 150 bar. The fraction of rounded cells after exposure to 1 microM chromate and 100 bar for 18 h was higher than would be expected if the effects were purely additive.

Actins↗
PubMed1978

[Correlation between changes in lungs caused by industrial dusts and the composition of amino acids in blood plasma. I. Experimental animal studies].

Animals, used for experiments, were intoxicated intratracheally with a suspension of grinding, ceramic or welding dust, in a NaCl solution. These studies demonstrated that the ceramic and welding dusts, used in the experiment, showed a rather great biological activity. This has been proved by the increased weight of dried lungs, and increased total content of some aminoacids in lungs, e.g. hydroxyproline, which is thought to be a reliable index of fibrosis of the pulmonary tissue, as well as of the change in the morphological structure of lungs. Parrallel to the mentioned changes of the lungs, the content of free aminoacids in the animals blood plasma has been remarkably reduced. The results described in this paper prove that there is a dependence between the content of aminoacids in the blood plasma and the changes in lungs caused by dust.

Amino Acids↗