The effect of different bearing surfaces on metal ion levels in urine following 28 mm metal-on-metal and 28 mm metal-on-polyethylene total hip arthroplasty.

BACKGROUND AND AIMS: Recent advancements in manufacturing technology have enabled more precise tolerances and surface finishes using metal-on-metal bearing surfaces in total hip arthroplasty. The aim of this study was to compare the level of metal ions in urine after implantation of a 28-mm metal-on-metal bearing manufactured from high-carbon wrought alloy and a 28-mm metal-on-polyethylene bearing. MATERIAL AND METHODS: A total of 92 total hip arthroplasty patients were prospectively randomized into two groups: those receiving metal-on-metal bearings and those receiving metal-on-polyethylene bearings. Chromium, cobalt, and molybdenum ion levels in urine were measured preoperatively and at 1 year and 2 years postoperatively. RESULTS: In the metal-on-polyethylene group, there was a slight increase in mean chromium and cobalt concentrations at 2-year follow-up compared to the preoperative level (p = 0.02 for both chromium and cobalt). In the metal-on-metal group, there was a 15-fold increase in chromium and a 26-fold increase in cobalt at 2-year follow-up compared to the preoperative level (p < 0.001 for both chromium and cobalt). However, the quantity of chromium and cobalt in urine from the metal-on-metal group was not higher at 2-year follow-up than at 1-year follow-up (p = 0.5 and p = 0.6, respectively). CONCLUSIONS: The 28-mm metal-on-metal bearings yield chromium and cobalt concentrations in urine that can be higher than those recommended for occupational exposure. However, our results also indicate that a steady state in wear and ion production using metal-on-metal total hip arthroplasty can occur.

[Symptoms and musculo-skeletal changes among personnel of the State Police exposed to mechanical risk]. / Sintomi ed alterazioni muscolo-scheletriche in personale della Polizia di Stato esposto a rischio biomeccanico.

The aim of this present study was to inquire about spine morfo-functional alterations among policemen with jobs regarded as potentially hazardous, in order to identify preclinical alterations of column and to plan adequate preventive measures. A physiopathologic and working anamnesis was carried out by means of questionnaire about personal data, jobs, reported rachidian symptomatology and presence of orthopedic diseases, given to policemen on duty in Bari. Every chosen worker was subject to orthopedic and neurological examination, radiography of column, Formetric tridimensional examination, telethermography of spine. We stratified the sample on the basis of age and job. Under the jobs we individuated 4 biomechanical hazardous activities, performed separately or together: driving motorcycle, driving car, flying helicopter, video terminal use. The whole sample, formed by 211 subjects, all male, had the average age of 39 years (Standard Deviation: +/- 4). About the reported rachidian symptomatology, only 41 (17, 98%) subjects were asymptomatical, contrary to clinical results, that were normal in almost the entire sample, with the exception of 3 workers (1, 31%), who had neurological clinical alterations. Structural alterations were checked by radiography among 64, 9% of subjects. The Formetric examination found alterations in different tract of rachis, also coexiting between each other. The telethermographic changes affected 63,99% of the sample and involved especially the lumbar tract (38,86%), dorsal region (18%) and cervical zone (7,1%). The relative frequency of dorsal tract increased with growing of age. The morfo-functional changes of the sample seem to depend rather on the performed job, than on degenerative process of age, partly because the average age of the sample is not much elevated and because the enlistment in Italian Police Force is subordinated to verification of optimum conditions, also characterized by absence of anomaly of column. The absence of clinical alteration, in contrast to reported rachidian symptomatology by 82,02% of subjects and with discovered objectivity, demands more clinical attention in presence of symptomatology and proposes supplementary non-invasive techiniques of investigation, as the telethermography and the formetric tridimensional examination.

Aggregation kinetics of thermal double donors in silicon.

A general kinetic model based on accurate density-functional-theoretic total-energy calculations is introduced to describe the aggregation kinetics of oxygen-related thermal double donors (TDD's) in silicon. The calculated kinetics, which incorporates the reactions of associations, dissociations, and isomerizations of all relevant oxygen complexes, is in agreement with experimental annealing studies. The aggregation of TDD's takes place through parallel-consecutive reactions where both mobile oxygen dimers and fast migrating chainlike TDD's capture interstitial oxygen atoms.

Structures of thermal double donors in silicon

Accurate total-energy calculations are used to study the structures and formation energies of oxygen chains as models for thermal double donors (TDD's) in Si. We find that the first three TDD's (TDD0-TDD2) consist of one four-member ring, with one or two adjacent interstitial O atoms. These metastable TDD's form bistable negative-U systems with the corresponding stable, electrically inactive staggered structures. The TDD3-TDD7 structures are found to consist of four-member rings with adjacent interstitial O atoms at both ends. The TDD's with a central "di-Y-lid" core are found to become energetically competitive with the four-member ring TDD's only for clusters larger than ten O atoms.

The effects of anabolic steroids on collagen synthesis in rat skeletal muscle and tendon. A preliminary report.

We measured the activities of prolyl 4-hydroxylase and galactosylhydroxylysyl glucosyltransferase (both enzymes of collagen biosynthesis) and the concentration of hydroxyproline in male rat soleus muscle and Achilles tendon during anabolic steroid treatment at 1 and 3 weeks. The rats were treated using a therapeutic dosage or a dosage that was five times the therapeutic level. After 1 week, the activity of prolyl 4-hydroxylase decreased significantly (P less than 0.01) in both treated groups in the soleus muscle, but the activity of galactosylhydroxylsyl glucosyltransferase decreased significantly (P less than 0.05) only in the group given a therapeutic dose. After 3 weeks, the activities were at the control level. In the Achilles tendon, the activity of prolyl 4-hydroxylase and the hydroxyproline concentration decreased significantly (P less than 0.05) in the group given high doses at 3 weeks. Anabolic steroid treatment seems to have at least a transitory effect on collagen biosynthesis in male rat muscle and tendon; in tendon this effect is seen only with high doses.

Cardiac glycosides in the treatment of experimental overdose with calcium-blocking agents.

The ability of digitalis compounds to counteract calcium antagonist overdose was studied in anesthetized dogs (n = 6, 13.5 +/- 0.7 kg) and isolated trabeculae from human hearts (n = 7). Digitalis caused by increasing intracellular cytosolic Ca2+ concentration through Na+/Ca(2+)-exchange across the cell membrane, was postulated to overcome the detrimental effects of excessive slow calcium-channel blockade. In anesthetized dogs, an infusion of verapamil (40 mg/30 min, i.v.) decreased mean arterial pressure from 88 +/- 6 to 66 +/- 6 mm Hg (P < 0.05), reduced systemic vascular resistance (SVR) from 3838 +/- 916 to 2200 +/- 669 dyne.s/cm5 (P < 0.05), and induced total atrio-ventricular (A-V) block in three animals. Stroke volume (SV) remained unchanged. Administration (i.v.) of NaCl (0.9%, 200 ml) and calcium gluconate (100 mg)--to increase the availability of Na+ and Ca(2+)--together with atropine (0.2 mg)--to block the parasympathetic effects of digoxin on A-V conduction--increased left ventricular contractility (15%) but had no significant effects on blood pressure, SV, or A-V block. Digoxin (0.125 mg) returned sinus rhythm in all dogs and, by increasing SVR (P < 0.05) and left ventricular contractility (P < 0.05), returned arterial pressures to baseline. Because of increased afterload, SV decreased slightly (15%) despite increased cardiac contractility. In experiments with isolated trabeculae from diseased human hearts, TA 3090 (Clentiazem) depressed contractile force and ouabain, another glycoside, restored contractile force within 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Reversibility of the haemodynamic effects of anabolic steroids in rats.

The haemodynamic effects of 6 weeks nandrolone decanoate treatment (total dose 30 mg.kg-1) (SG I, n = 12) and their reversibility were studied in anaesthetised, open-chest male rats exposed to 5 min isoproterenol (2.5 micrograms.kg-1) and CaCl2 (25.0 mg.kg-1) loads. In SG I, the heart weight and its ratio to body weight were greater than in the untreated rats (CG I, n = 13) (p less than 0.05 and p less than 0.01 respectively). The initial heart rate and the inotropic and chronotropic responses to isoproterenol were lower in SG I than in CG I (p less than 0.05 in all cases). Peripheral resistance decreased during both infusions in SG I but remained unaltered in CG I (p less than 0.05). 6 weeks after finishing anabolic steroid treatment (SG II, n = 11), in the CaCl2-test the ejection fraction (p less than 0.05) and stroke index were smaller than in control rats of the same age (CG II, n = 12). Mean aortic pressure was lower in SG II than in CG II. In the CaCl2-test peripheral resistance was initially higher, but decreased during the infusion in SG II while it increased in CG II (p less than 0.05 in both cases). In conclusion, anabolic steroid treatment reversibly reduces the left ventricular response to isoproterenol. It decreases peripheral vascular tone during inotropic loads. Six weeks after the cessation of treatment, the pumping efficiency of the heart is reduced.

[Pneumoconiosis in bauxite miners]. / Pneumoconiosi in minatori di bauxite.

The authors examined a group of 40 miners who were being working at an Apulian bauxite mine, presently inactive. Radiographic findings of pulmonary micronodulation without significant reduction of lung functions were showed in 15 miners. Mineralogical analysis of mine dust samples excluded any presence of more than 1% free silica. As a result of this study hypotheses have been formulated about pathogenesis of this moderated and non-invasive pneumoconiosis, showed in long exposed subjects to low silica content dusts.