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PubMed1990

Small-airways dysfunction in never smoking asbestos exposed Danish plumbers.

Among 701 Copenhagen plumbers we examined the lung function of 23 never smokers, who had removed asbestos insulation and intermittently been exposed to high levels of asbestos for about 25 years without being exposed to welding fume. The plumbers had significantly lower TLC, MEF25, MEF50, closing volume and closing capacity in comparison to 23 never smoking electricians without asbestos exposure. There was no reduction in TLCO. Pulmonary clearance of aerosolized 99mTc-DTPA was normal indicating that the asbestos had not induced increases in pulmonary epithelial permeability. However, in 11 of the 23 plumbers the 99mTc-DTPA ventilation scintigrams had a slightly irregular and spotty appearance, which together with the results of the lung function tests are suggestive of small airways' dysfunction. None of the subjects had symptoms or clinical signs of lung disease.

Adult↗
PubMed1982

[Magnetic shielded room to measure very low magnetic and electric fields].

An extraordinary magnetically shielded room was designed and constructed for the Physikalisch-Technische Bundesanstalt Institut Berlin to measure extremely weak magnetic fields of the human body with SQUID-magnetometers. The inner and the outer dimensions of the cube-shaped room are 2.25 m and about 5 m. The shield has 6 magnetic shells of a high-permeability alloy and an inner shell welded of massive copper plates. The total weight of the magnetic alloy is about 10 t and about 5 t for the inner copper shell. The required shielding factor of 1000 for the very low frequencies was greatly surpassed by the real measured value of 10000 (measured without any compensating or idealizing method). With rising frequencies the shielding factor reaches higher values, at 50 Hz more than 100000 and a million for 1000 Hz. First measurements in the shielded room with high-resolution magnetocardiograms (HR MCG) and high-resolution electrocardiograms (HR ECG) showed new methods for non-invasive electrophysiological investigations in man.

Electricity↗
PubMed1990

Incidence of leukaemia and brain tumours in Finnish workers exposed to ELF magnetic fields.

The relative incidence of leukaemia, acute myeloid leukaemia (AML) and central nervous system (CNS) tumours among workers presumably exposed to extremely low frequency (ELF) magnetic fields (MFs) was studied. The study population consisted of all male industrial workers in Finland aged 25 to 64 years during 1971-1980 according to the Population Census in 1970. The occupations were grouped into three exposure categories according to the probability of exposure. The category of "probable" exposure included electrical occupations and the category of "possible" exposure included occupations where electric motors or welding are common. All other occupations were included to the category of "no exposure". Cancer incidence rates in different occupational groups during 1971-1980 were obtained after linking the census records with the national death certificates and the files of the Finnish Cancer Registry. The adjusted relative risks (with 95% confidence limits) in the categories of "probable" and "possible" exposure were for all leukaemia 1.9 (1.0-3.5) and 1.4 (1.1-1.8), for AML 1.5 (0.5-4.7) and 1.4 (0.9-2.1), and for CNS tumours 1.3 (0.7-2.3) and 1.3 (1.0-1.6), respectively. The results are concordant with earlier studies suggesting elevated risk among workers exposed to ELF magnetic fields.

Adult↗
PubMed1993

Accelerometric assessment of osseous union.

Study of the dynamic structure response of the long bone has demonstrated the potential to provide an objective quantitative test of fracture healing. The method described consists of monitoring the propagation of a mechanical wave across the fracture site. This wave--generated by the fall of a steel ball from a constant height on a subcutaneous bony protuberance--was monitored on the side opposite the fracture gap by a light-weight accelerometer and traced on a beam-storage oscilloscope. The signals received were found to correlate linearly with the different stages of the fracture welding, as shown by accepted clinical and radiological practice. It seems feasible that the method, being noninvasive, reproducible, simple, painless, and inexpensive, may be used to measure the parameters of fracture healing that are of clinical and scientific interest.

Child↗
PubMed1995

Analysis of fracture toughness data.

In studies of the fracture toughness of irradiated weld metal, specimens are subjected to an increasing load. The test on any one specimen might be terminated by choice or because the specimen ruptures. Prior to termination, ductile tearing might or might not have occurred. The situation is thus basically one of competing risks, with different types of termination, but there are additional features. The major purpose of statistical analysis is to estimate probabilities concerning the values of "toughness" and crack length. The analysis has been based on a model developed for the joint survivor function of these quantities.

Humans↗
PubMed1991

Valve disruption for in situ vein bypass: use of a new technique.

Following its introduction in 1960, the in situ bypass technique has gradually gained acceptance among vascular surgeons. This can be explained, in part, by the lack of a reliable method for rendering vein valves incompetent. Several instruments developed by Skagseth and Hall, Leather and Karmody, and others have been used. Although most are relatively easy to use, one common drawback is the difficulty in controlling rotation of the cutting blade. This is due to insufficient torsional rigidity of the shaft and the lack of a blade plane indicator. Edwards, in 1936, described the consistent orientation of vein valves, whose margins are always parallel to the overlying skin surface. This knowledge facilitates complete midline incision of the valve cusps, provided that the surgeon is able to control the cutting blade. With this fact in mind, we have developed a new set of instruments. They feature satisfactory torsional rigidity, as well as blade plane indicators at the handle. For the endoscopist, the blade plane is made visible by a mark at the tip of each instrument. Precision-manufactured of stainless steel and welded with laser technology, the instruments are suitable for multiple use, which we consider an advantage from an economic, as well as an ecological viewpoint.

Equipment Design↗
PubMed1992

First experimental sutureless end-to-end laser anastomosis of the large bowel. Short-term results.

Completely sutureless end-to-end large bowel anastomoses were successfully created in New Zealand white rabbits (n = 26) by using a low-energy (0.4-W wave of power) Nd:YAG laser to produce welded anastomoses. In this study, the short-term integrity, degree of narrowing, macroscopic appearance, and microscopic findings were compared with those of the conventional interrupted one-layer anastomosis (n = 24) at zero, one, four, and seven days after surgery. Two rabbits in the laser group died from leakage. All remaining animals had an uneventful postoperative course. The bursting pressures in the laser group at zero, one, and four days were lower than those in the control group. The narrowing index of the laser anastomosis was higher than that of the suture anastomosis at four and seven days. However, the laser anastomoses showed fewer adhesions, no instances of bowel obstruction, and histologic healing with less fibrosis. The technique of laser anastomosis presents a promising alternative to suturing in reconstitution of the large bowel.

Anastomosis, Surgical↗
PubMed1989

[Materials science studies on the soldering of different orthodontic wires].

In orthodontic technique both soldering and welding are standard methods for the application of auxiliaries and for the modification of force systems by joining wires of different cross-sections. Two cobalt-chromium alloys (Blue Elgiloy, Crozat) and an austenitic stainless steel alloy (Remanium) were soldered by an electrochemically generated hydrogen-oxygen flame forming an overlapped joint design. For characterization of the soldered joint testing procedures included microhardness tests, metallographic examination, tension-shear tests and surface analysis of the fractured joints by scanning electron microscopy. For any given soldering technique with an overlapped joint design the correct joint length is determined by the ratio t/s = 3 (t = overlapped length; s = diameter of the smaller wire).

Dental Alloys↗
PubMed1995

[A functional orthodontic magnetic appliance (FOMA) after Vardimon. 1. A three-dimensional analysis of the force system of the attractive magnets].

The functional magnetic system (FMS) is a removable functional appliance which induces mandibular advance by means of mandibular and maxillary magnets in an attracting configuration. The maxillary and mandibular plates are each equipped with 2 cylindrically shaped cobalt-samarium magnets, 4 mm in diameter and 3 mm in height, which are welded into stainless steel housings. The force system of this magnetic configuration was analyzed using the orthodontic measurement and simulation system (OMSS). OMSS simulated the mandibular jaw movements by separating the installed magnets vertically, corresponding to a mouth opening of X = -10 mm, transversally (right excursion, +/left excursion, -) at Y = +/- 10 mm and sagittally (anterior displacement, +/posterior displacement, -) at Z = +/- 10 mm. The resulting 2D and 3D force/displacement diagrams elucidate the outstanding centripetal-spatial orientation characteristics of the functional magnetic appliance in reference to the full overlap brought about by the attraction of the mandibular magnet by the maxillary magnet. The maximum centripetal forces reached a value of approximately FY, max = 0.65 N for the vertical attracting force at full overlap of the mandibular and maxillary magnets (X = 0.55 mm, Y = Z = 0 mm), a value of FY, max = 0.65 N for the medial shearing force at a partial transversal overlap Z = 0, Y = +/- 2 mm and Y = +/- 6 mm), and for the sagittal shearing force a value of FZ, max = 1.2 N at a partial sagittal overlap of the magnets (Y = 0 mm, Z = +/- 2 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Cobalt↗
PubMed1998

Comparison of multipole and mean value methods to quantify dust in human lungs: simulating the magnetopneumography procedure.

Magnetopneumography (MPG) can quantify the retention of magnetisable particles in the lung acquired, for instance, in welding work. MPG is non-invasive and is used in occupational health, industrial hygiene and lung physiology. Following a brief magnetisation, the remanent magnetic field is mapped with magnetometers outside the thorax. There is no unique analytical inverse solution to this class of magnetostatic problem, and various inverse methods have been proposed. In the present study, the influence of variations in size and shape of the lungs and chest, magnetic measurement noise, positional noise and spatial dust distribution are investigated in five inverse methods. The mean value of the field map, calibrated against a lung phantom, is the commonly used method. Lung and chest size influence the mean value method solutions strongly. Correction for chest size reduces these errors, but bias errors and sensitivity to the deposition pattern remains a problem. A multipolar expansion, including dipolar, quadrupolar and octopolar moments, yields best results overall, provided the single-to-noise ratio is sufficient. This inverse solution is unbiased, requires no calibration with phantom lung models and serves to minimise errors due to inter-individual differences in anatomy and to inhomogeneous retention of inhaled dust.

Dust↗
PubMedDate not supplied

Circaseptan (about-7-day) bioperiodicity--spontaneous and reactive--and the search for pacemakers.

A built-in (genetically determined) about-7-day (circaseptan) period comes to the fore as a desynchronized feature of human time structure in the urinary excretion of 17-ketosteroids by a clinical healthy man: during several years following an endocrine intervention (the self-administration of testosterone suppositories), a circaseptan rhythm (which during the preceding decade had revealed a period of precisely 7 days) deviated slightly, yet with statistical significance, from the environmental week. A second line of evidence for an intrinsic circaseptan component stems from the demonstration of statistically significant differences in timing of a circaseptan rhythm in springtail oviposition. A third line of evidence documents prominent circaseptan rhythmicity after the application of a single stimulus (devoid in itself of any circaseptan information). Such single stimulus induction, amplification and/or synchronization also documents the clinical and biologic importance of built-in circaseptan rhythms that were previously often misinterpreted as being purely reactive: a circaseptan spectral component is remarkably prominent in mammalian organ transplant rejection, both in the clinic and in the laboratory. In the latter case, in the absence of any weekly cycles in hospital routine, including treatment schedules, circaseptan components characterize the rejection of the rat kidney, pancreas and heart. Much additional information here reviewed reveals the occurrence of periods of about 7 days. Their implications for transplant and other chronoimmunology as well as biology in general, and their clinical applications in drug treatment, include the need to weld circaseptan timing to circadian timing and dosing. A dramatic documentation of this need stems from the circumstance that pretreatment for one week with the same total dose of the same substance (a polysaccharide - Lentinan) accelerates or retards cancerous growth (hence shortens or lengthens survival) as a function of interactive circaseptan and circadian rhythms.

17-Ketosteroids↗
PubMed2000

Successful treatments of lung injury and skin burn due to hydrofluoric acid exposure.

Recent growth in the electronics and chemical industries has brought about a progressive increase in the use of hydrofluoric acid (HF), along with the concomitant risk of acute poisoning among HF workers. We report severe cases of inhalation exposure and skin injury which were successfully treated by administering a 5% calcium gluconate solution with a nebulizer and applying 2.5% calcium gluconate jelly, respectively. Case 1: A 52-year old worker used HF for surface treatment after welding stainless steel, and was hospitalized with rapid onset of severe dyspnea. On admission to the critical care medical center he had widespread wheezing and crackles in his lungs. Chest radiograph showed a fine diffuse veiling over both lower pulmonary fields. Severe hypocalcemia with high concentrations of F in serum and urine were disclosed. He was immediately given 5% calcium gluconate solution by intermittent positive-pressure breathing (IPPB), utilizing a nebulizer. On the 21st hospital day, chest film and CT scan did not demonstrate any abnormality. He was discharged very much improved on the 22nd hospital day. Case 2: A 35-year old worker at an electronics factory was admitted to his local hospital with severe skin burn on his face and neck after exposure to 100% HF. Treatment began with immediate copious washing with water for 20 min. Calcium gluconate 2.5% gel (HF burn jelly) was applied to the area as a first-aid measure. Persistent high concentrations of serum and urinary F were disclosed for 2 weeks. After treatment with applications of HF burn jelly, he was confirmed as being completely recovered. The present cases and a review of published data suggest that an adequate method of emergency treatment for accidental HF poisoning is necessary.

Administration, Topical↗
PubMed2006

Magnetic field exposure and neurodegenerative diseases--recent epidemiological studies.

OBJECTIVES: To analyse the results of recent studies not yet included in a 2003 report of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) on occupational exposure to low-frequency electromagnetic fields as potential risk factor for neurodegenerative diseases. METHODS: A literature search was conducted in the online databases of PubMed, ISI Web of Knowledge, DIMDI and COCHRANE, as well as in specialised databases and journals. Eight studies published between January 2000 and July 2005 were included in the review. RESULTS: The findings of these studies contribute to the evidence of an association between occupational magnetic field exposure and the risk of dementia. Regarding amyotrophic lateral sclerosis, the recent results confirm earlier observations of an association with electric and electronic work and welding. Its relationship with magnetic field exposure remains unsolved. There are only few findings pointing towards an association between magnetic field exposure and Parkinson's disease. CONCLUSIONS: The epidemiological evidence for an association between occupational exposure to low-frequency electromagnetic fields and the risk of dementia has increased during the last five years. The impact of potential confounders should be evaluated in further studies.

Alzheimer Disease↗
PubMed2003

Metallographic structure and hardness of titanium orthodontic brackets.

AIM: To determine the elemental composition, microstructure, and hardness of two different brands of titanium (Ti) orthodontic brackets. MATERIALS AND METHODS: Four specimens of each brand were embedded in epoxy resin and, after metallographic grinding and polishing, were studied under a metallographic microscope. The bonding base morphology of each bracket was studied in as-received brackets by scanning electron microscopy. Energy dispersive x-ray microanalysis (EDS) was used on polished specimens to assess the elemental composition of base and wing bracket components, and the brackets were subjected to metallographic etching to reveal the metallurgical structure. The same specimen surfaces were used for assessment of the Vickers hardness. The results were statistically analyzed by two-way analysis of variance (ANOVA) with the bracket brand and bracket region (base, wing) serving as discriminating variables, whilst further group differences were investigated with Tukey's multiple comparison test at the alpha = 0.05 level of significance. RESULTS: Metallographic imaging revealed that the Orthos2 brackets (Ormco, Glendora, CA, USA) consist of two parts joined together by laser welding, with large gaps along the base wing interface, whereas Rematitan brackets (Dentaurum, Ispringen, Germany) are single-piece appliances. Ti was the only element identified in Rematitan and Orthos2 base materials, while aluminium (Al) and vanadium (V) were also found in the Orthos2 wing component. Metallographic analysis showed the presence of a + b phase for Orthos2 and plate-like grains for Rematitan. The results of the Vickers hardness testing were: Orthos2 (wing): 371 +/- 22, Rematitan (wing): 272 +/- 4, Rematitan (base): 271 +/- 16, Orthos2 (base): 165 +/- 2. CONCLUSION: The findings of the present study suggest that there are significant differences in composition, microstructure and hardness between the two commercial types of Ti brackets tested; the clinical implications of the findings are discussed.

Alloys↗
PubMed2005

Management of an extremely displaced maxillary canine.

CASE REPORT: Aligning a displaced maxillary canine into the dental arch is one of the most complicated problems in orthodontics. In cases of extremely high displacement, the tooth is frequently removed surgically. Because of the upper canines' significance to dental esthetics and functional occlusion, such a decision is a very serious one. This case report illustrates the treatment of an extremely high displaced maxillary canine. CLINICAL FINDINGS: The main diagnosis was the displacement and the retention of tooth 13 (in nearly horizontal position, apical to the neighboring teeth); further diagnoses were: transversal maxillary deficiency with frontal crowding and a distal bite of one premolar in width, a deep bite of 6 mm with contact in the palatal mucosa, mandibular midline deviation of 2.5 mm to the right, lingual eruption of teeth 32 and 42, retroinclination of the maxillary incisors, and retarded eruption of the permanent teeth. THERAPY: Initial treatment with active and functional appliances to correct the distal bite, midline deviation and deep bite. Surgical exposure of the high displaced canine at the age of 14. Onset of cuspid elongation with removable appliances and elastics, further movement with a transpalatinal bar and welded arm, and full alignment of the upper and lower arches with fixed appliances in both jaws. Stabilization of the orthodontic treatment results with retention devices. Duration of treatment: 5 years and 8 months. For the alignment of tooth 13, 2 years and 10 months were required; 1 year and 4 months were necessary with complete fixed appliance. CONCLUSIONS: The aim of this case report was to demonstrate the potential of aligning an extremely displaced canine. Because of the esthetic and functional importance of the upper canines, therapeutic alignment should be initiated, provided there are no indications to the contrary.

Child↗
PubMed1998

[Cold deformation elements for attaching an implantable hearing aid transducer to ear ossicles or perilymph].

Development and short-term implantation results of the Tübingen implantable hearing aid (TI = Tübingen implant) have been presented. The TI is designed for patients with sensorineural hearing loss due to a malfunction of the cochlear amplifier. This can be identified by the presence of positive recruitment and the absence of TEOAE (transitory evoked otoacoustic emissions). The Tübingen implant functions in two ways: it allows electronic amplification of the auditory signal and electromechanical signal transduction into a micromechanical vibratory stimulus. There are two paths by which vibratory stimulus reaches the cochlea: (1) directly through a perforation in the stapes foot plate into the perilymph or (2) via the ossicular chain. Made of pure titanium, the casing of the helium-tight welded transducer includes the piezoelectric actuator. An implantable manipulator device is designed for transducer positioning and anchoring in the mastoid cavity. Usually, the transducer probe tip is directly coupled to the body of the incus. This functions without a special coupling device by utilization of an Erbium-YAG laser. Special anatomical situations or the loss of incus and/or stapes suprastructure, however, requires coupling of the vibratory signal to other points of the ossicular chain or to the perilymph. A major problem, however, was an intraoperative, irreversible link between the titanium probe tip and coupling elements. To overcome this problem, the coupling elements were made of gold. A crimp technique was developed, allowing the surgeon to induce cold deformation of the gold. The cold deformation technique (crimp) results in an irreversible coupling between the titanium probe tip and the golden coupling element.

Cochlear Implantation↗
PubMed2003

Development of analytical procedures for determination of total chromium by quadrupole ICP-MS and high-resolution ICP-MS, and hexavalent chromium by HPLC-ICP-MS, in different materials used in the automotive industry.

A European directive was recently adopted limiting the use of hazardous substances such as Pb, Hg, Cd, and Cr(VI) in vehicle manufacturing. From July 2003 a maximum of 2 g Cr(VI) will be authorised per vehicle in corrosion-preventing coatings of key components. As no standardised procedures are available to check if produced vehicles are in agreement with this directive, the objective of this work was to develop analytical procedures for total chromium and Cr(VI) determination in these materials. The first step of this study was to optimise digestion procedures for total chromium determination in plastic and metallic materials by inductively coupled plasma mass spectrometry (ICP-MS). High resolution (HR) ICP-MS was used to examine the influence of polyatomic interferences on the detection of the (52)Cr(+) and (53)Cr(+) isotopes. If there was strong interference with m/ z 52 for plastic materials, it was possible to use quadrupole ICP-MS for m/ z 53 if digestions were performed with HNO(3)+H(2)O(2). This mixture was also necessary for digestion of chromium from metallic materials. Extraction procedures in alkaline medium (NH(4)(+)/NH(3) buffer solution at pH 8.9) assisted by sonication were developed for determining Cr(VI) in four different corrosion-preventing coatings by HPLC-ICP-MS. After optimisation and validation with the only solid reference material certified for its Cr(VI) content (BCR 545; welding dusts), the efficiency of this extraction procedure for screw coatings was compared with that described in the EN ISO 3613 standard generally used in routine laboratories. For coatings comprising zinc and aluminium passivated in depth with chromium oxides the extraction procedure developed herein enabled determination of higher Cr(VI) concentrations. This was also observed for the screw covered with a chromium passivant layer on zinc-nickel. For coating comprising a chromium passivant layer on alkaline zinc the standardized extraction procedure was more efficient. In the case of painted metallic plate, because of a reactive matrix towards Cr(VI), its extraction without degradation was difficult to perform.

Journal Article↗
PubMed1996

MRI in children receiving total parenteral nutrition.

Cranial MRI was obtained in 13 of a group of 57 children receiving long-term parenteral nutrition, who were being investigated for hypermanganasaemia. Increased signal intensity on T1-weighted images has been reported in adult patients on long-term parenteral nutrition and with encephalopathy following chronic manganese exposure in are welding. It has been postulated that these changes are due to deposition of the paramagnetic trace element manganese. In excess manganese is hepato- and neurotoxic and we present the correlation of whole blood manganese levels with imaging findings. The age range of our patients was 6 months to 10 years, and the duration of therapy 3 months to 10 years. In 7 children we found characteristic increased signal intensity on T1-weighted images, with no abnormality on T2-weighted images. All patients had elevated whole blood manganese levels, suggesting that the basis for this abnormality is indeed deposition of manganese within the tissues.

Brain↗