Farm work-related injury among middle school students in rural China.

Farm work-related injuries are considered an important issue facing rural area adolescents. However, little research has been done in developing countries, including China. This study evaluated agricultural work-related injuries among Chinese middle school adolescents, focusing on the potential association between farm work hours, sleep patterns, school-related stress, and farm work-related injuries. This cross-sectional study surveyed 1,551 middle school students in Hunan Province who reported working on farms. The surveys assessed their involvement in farm work, sleep patterns, school activities, and farm work-related injuries during a three-month recall period. The cumulative incidence of farm work-related injury was 15.6% among the 1187 students who reported working on a farm. Average days per month farming, number of pesticide applications per month, sleep disturbances, and school-related stress were significantly associated with farm work-related injuries (p < 0.05). Multivariable logistic regression analysis revealed that after adjusting for possible confounding effects of age, gender, and farm work days per month, sleep disturbance (less than 7 hours of sleep: OR = 2.36, 95% CI = 1.07-5.22; awakening at night and having trouble falling back to sleep: OR = 2.70, 95% CI = 1.36-5.37; having nightmares: OR = 2.24, 95% CI = 1.18-4.24) and school-related stress (difficult homework: OR = 2.45, 95% CI = 1.21-4.99; extra homework assigned often by parents: OR = 3.62, 95% CI = 1.88-6.97; and scolded/chastised by parents for poor school performance: OR = 2.53, 95% CI = 1.75-3.65) were statistically significant risk factors for farm work-related injuries (p < 0.05).

Infection in massive bone allografts sterilised by radiation.

Massive bone allografts sterilised by radiation have been used in our hospital since 1985. The 164 consecutive reconstructions which we carried out before December 1990 were in equal part for tumour resections and revision arthroplasties associated with major bone defects. The allografts were used as intercalary or composite graft-prosthesis reconstructions. Fourteen (8.5%) skin sloughs or infections occurred, all but one after operations for malignant tumours. The grafts never appeared to be responsible. Infection after malignant tumour resection most commonly occurred at the knee when preoperative radiation had been used. Twenty-five reconstructions were performed in the presence of infection, which only recurred in one case. Twelve infections were treated, but 2 other patients died for other reasons within a year. One patient had to have an amputation and one had persistent infection. In the other cases, the infection healed. Only two debridements alone were successful. Removal of the graft and replacement with antibiotic-loaded cement was the most effective treatment.

Biodistribution and excretion of a mixed fluorocarbon-hydrocarbon "dowel" emulsion as determined by 19F NMR.

To investigate the biodistribution, possible metabolism and excretion of mixed fluorocarbon-hydrocarbon "dowel" molecules used as stabilizers of fluorocarbon emulsions, we have prepared a 25% w/v emulsion of such a molecule, and quantitatively evaluated, by means of 19F NMR, its behavior in the blood and reticuloendothelial system (RES) of rats. C6F13CH = CHC10H21 (F6H10E) was emulsified using egg yolk phospholipids (EYP). The emulsion (F6H10E/EYP: 25/6% w/v) was injected intravenously into 33 Sprague Dawley female rats at a 3.6 g/kg body weight dose of F6H10E. The animals were sacrificed at regular intervals of time. 24 hours after the injection, 70% of the injected dose was located in the liver, 17% in the spleen, 4% in the lungs, 2% in the kidneys and 2% in the blood. The half-time retention of the dowel molecule in the liver was estimated to be 25 +/- 5 days. None of the 33 treated animals died prior to the planned sacrifice date. The dowel molecule F6H10E proved to be well tolerated, and excreted reasonably fast, without metabolism. This appears to warrant the use of such molecules as stabilizers in injectable fluorocarbon emulsions destined to serve as oxygen carriers, contrast agents or drug delivery systems.

Fluorocarbon emulsions--the stability issue.

Long-term room temperature stability of ready-to-use concentrated fluorocarbon emulsions is necessary in order to fully exploit the therapeutic potential of fluorocarbons. Consequently, considerable efforts have been directed at investigating the physical nature of such emulsions, the mechanisms which lead to their degradation and the means of counteracting these. The particles which constitute typical fluorocarbon/egg yolk phospholipid emulsions have been identified to be surfactant-coated fluorocarbon droplets and lipid vesicles. Better understanding has been gained on the formation, structure and evolution of these particles during processing and storage. This has led to optimized formulations and processing, better control of emulsion characteristics and significantly improved stability. Molecular diffusion (Ostwald ripening or transcondensation) has been shown to be the maun mechanism of degradation when particles are less than 1 micron in diameter, even for the highly concentrated (volume fraction of fluorocarbon up to 50%) second generation fluorocarbon emulsions. Significant emulsion stabilization has been accomplished by adding fluorochemicals which are both less volatile and less water soluble, and nevertheless have an organ dwell time acceptable for intravascular use. The rate of molecular diffusion can also be reduced by decreasing the fluorocarbon/water interfacial tension; this was effectively achieved with appropriate, well-defined fluorinated surfactants. A further, novel means of stabilizing fluorocarbon-in-water emulsions makes use of mixed fluorocarbon-hydrocarbon amphiphiles which act as molecular dowels to reinforce the adhesion between the fluorocarbon phase and the lipophilic zone of the surfactant film. Both long-term room temperature stability, and particle-size control over a large range of diameter, have been achieved by applying this principle. All in all it can be said that the challenge of producing injectable fluorocarbon emulsions with long-term room temperature particle size stability has been met.

Biodistribution of mixed fluorocarbon-hydrocarbon dowel molecules used as stabilizers of fluorocarbon emulsions: a quantitative study by fluorine nuclear magnetic resonance (NMR).

19F NMR spectroscopy was used to determine quantitatively the organ distribution and organ retention time in rats of the mixed fluorocarbon-hydrocarbon dowel molecule C6F13CH = CHC10H21 (F6H10E), which stabilizes highly concentrated injectable fluorocarbon emulsions destined for in vivo oxygen transport and delivery. The only fluorine resonances detected in the 19F NMR spectra of the organs analyzed were those of the F6H10E dowel itself, indicating that metabolites, if present, have very low concentrations (< 10(-4) M, limit of our assay). The F6H10E content in the liver peaked 1 day after administration (7 days for the spleen). At a dose of 3.6 g/kg body weight, the half-life of F6H10E in the liver was 25 +/- 5 days.

[One stage revision of infected total hip replacements with replacement of bone loss by allografts. Study of 90 cases of which 46 used bone allografts]. / Remplacements en un temps des prothèses totales de hanches infectées et reconstructions osseuses par allogreffes. Etude de 90 reprises dont 46 avec allogreffes osseuses.

We usually manage infected total hip replacements by a one stage revision. We have reviewed 90 cases operated on before 1988. Notable bone loss was frequently encountered and reconstructed using allografts. In all cases complete surgical debridement was performed and a cemented total hip replacement implanted. Bone allografts were used in 46 cases. Systemic antibiotics and antibiotic loaded cement were utilised. There were 17 failures (19%); one patient died soon after operation, there were 8 obvious infections (9%), 1 hip was thought to be infected although the prosthesis was not loose, and 7 femoral prostheses became loose of which 3 were due to mechanical failure and the remainder had no obvious explanation. Infection with staphylococcus aureus and pseudomonas had a statistical correlation with failure, but other factors including the preoperative status and the use of allografts did not appear to influence the result. Allograft femoral heads from the bone bank were found to be reliable for reconstruction of the acetabulum and small femoral defects. With major femoral bone loss we preferred massive irradiated cortical allografts. The quality of the bone reconstruction was probably the most important factor in the good functional results observed in 79% of cases. Effective surgical debridement and an appropriate antibiotic regime will allow a successful one stage revision procedure. The use of allografts gave a reliable reconstruction of the bone loss and was not associated with an increased rate of failure.

Stability and stabilization of fluorocarbon emulsions destined for injection.

The factors that have an impact on the stability, and the mechanisms of degradation of fluorocarbon emulsions suited for intravascular use, are briefly reviewed. Various ways of prolonging shelf stability are discussed. The effectiveness of perfluoroalkylated surfactants and/or co-surfactants as stabilizers is demonstrated. New means of stabilizing fluorocarbon-in-water emulsions using molecular dowels are presented.

Drop size stability assessment of fluorocarbon emulsions.

The aging of fluorocarbon emulsions prepared with natural egg yolk phospholipids (EYP) has been studied and a linear variation (r2 greater than 0.95) of the mean average volume of the droplets with time has been observed. The slope of the experimental lines, called "Stability Parameter, S" can thus be taken as a representation of the rate of aging of the emulsions. Examples are given of use of parameter S to assess the effect of formulation and processing parameters on the stability of diverse fluorocarbon emulsions. S is a useful tool to compare emulsions and ascertain any factors of stabilization/destabilization.

Histological patterns of bone and articular tissues after orthopaedic reconstructive surgery (artificial joint implants).

Revision surgery after failures of joint replacements leads to histological studies on joint and bone tissues close to the implanted material. Aspectic loosening is the main complication. The surgical pathologist has to identify wear debris (metal, polyethylene, polymethylmethacrylate, chiefly) which promotes a histiocytic granuloma. Some surgical procedures such as cup or resurfacing arthroplasties create a new articular surface and a bone remodeling or necrosis. Cemented joint prostheses show various membrane structures between bone and the cement mantle while there is an association of bone resorption and formation. Non-cemented, porous-coated joint prostheses induce little bone ingrowth, even in satisfactory clinical results. Mechanical factors are predominant in massive limb prostheses. For silicone elastomer implants or artificial ligaments, wear of material promotes many tissular reactions. Often used bone grafts show little creeping substitution process in case of homografts, even well-incorporated on X-rays. More retrieval specimen studies are necessary to delineate precise topographical histological lesions, including non-loosened joint implants.

Fluorocarbon/lecithin emulsions: identification of EYP-coated fluorocarbon droplets and fluorocarbon-empty vesicles by freeze-fracture electron microscopy.

Freeze-fracture has been used to examine perfluorodecalin/egg yolk phospholipid emulsions (70:8, w/v%) destined to be used as injectable oxygen carriers. The fluorocarbon displays a specific granular aspect upon freeze-fracture which makes it readily recognizable and allows the distinction between two populations of objects on the micrographs: fluorocarbon droplets and water-filled lipid vesicles.

Prevention of deep vein thrombosis after hip replacement: randomised comparison between unfractionated heparin and low molecular weight heparin.

OBJECTIVE: To evaluate the efficacy and safety of two subcutaneous prophylactic regimens for postoperative deep vein thrombosis after total hip replacement. DESIGN: Prospective open randomised multicentre trial. SETTING: 28 European departments of orthopaedic surgery. INTERVENTION: All patients had bilateral phlebography 10 days after surgery. 31 patients receiving low molecular weight heparin and 29 receiving unfractionated heparin were excluded from the efficacy analysis for various reasons. PATIENTS: 349 patients undergoing total hip replacement between September 1988 and May 1989. 174 patients received subcutaneously a low molecular weight heparin (Fraxiparine) with anti-factor Xa activity of 41 IU/kg/day for three days, then 62 IU/kg/day from day 4 to day 10. 175 patients received subcutaneous unfractionated heparin at intervals of eight hours; doses were adjusted to maintain the activated thromboplastin time at two to five seconds above control values. MAIN OUTCOME MEASURE: Total incidence of deep vein thrombosis and incidence of proximal deep vein thrombosis on bilateral phlebography. RESULTS: The total incidence of deep vein thrombosis was 16% in patients receiving unfractionated heparin and 12.6% in patients receiving low molecular weight heparin (p = 0.45), and the incidence of thrombosis of the proximal veins was 13.1% and 2.9% respectively (p less than 0.001). Four patients receiving unfractionated heparin and one receiving low molecular weight heparin developed pulmonary embolism. The incidence of bleeding complications was low and comparable in the two groups. CONCLUSION: Low molecular weight heparin is at least as effective as unfractionated heparin in preventing deep vein thrombosis and is more effective at preventing thrombosis of the proximal veins in patients undergoing hip replacement. Low molecular weight heparin is not more likely to cause bleeding complications and is simpler to give than unfractionated heparin.

[A new trochanteric osteotomy method for a postero-lateral approach of the hip (330 operations with posterior transosseus and paramuscular curved approach]. / Une nouvelle trochantérotomie pour l'abord postéro-externe de la hanche (330 interventions avec abord arciforme postérieur, trans-osseux et para-musculaire).

The authors studied a series of 330 Total hip replacements with 6 months to 4 years follow-up, in order to define a new trans-trochanteric approach. The procedure, with a two slope trochanterotomy, is a curved posterolateral approach. The shell bone, with attachment of Mm gluteus, M. vastus lateralis and M. piriformis is pushed forward. The other pelvic-trochanteric muscles stay with the femoral shaft. Two revisions (0.6 per cent) had to be performed because a faulty accomplishment of the trochanteric osteotomy. The trochanteric fusion was always achieved. One third of the hips was stable at one month post-op and 95 per cent at 6 months. This approach is a variable of the conventional transtrochanteric approach and it seems to decrease markedly its disadvantages.

[Efficacy and tolerance of low molecular weight heparin in the prevention of deep venous thrombosis during non-emergent total hip arthroplasty. A prospective, multicenter trial]. / Efficacité et tolérance d'une héparine de bas poids moléculaire dans la prévention des thromboses veineuses profondes lors des arthroplasties totales de hanche réglées. Essai prospectif, multicentrique.

A multicenter prospective trial was conducted on 149 patients to test the efficacy and tolerance of low molecular weight heparin (LMWH) in the preventive treatment of deep venous thrombosis consecutive to total hip arthroplastic surgery. An original dose-adjusted protocol was tested, whereby the patients were injected a single dose of LMWH daily, determined on a weight and operation date basis; the prophylactic efficacy of this protocol was assessed by bilateral phlebography performed systematically on the 10th postoperative day. Only 12.9% of patients developed deep venous thrombosis of the lower extremities, and the thrombus formation site was proximal in 3.6% of cases. These rates are low compared with published data and considering the diagnostic criterion used. The low incidence of premature treatment withdrawal and hemorrhagic complication (2%) cases is indicative of the good tolerance of this preventive treatment.

Bone allografts sterilised by irradiation. Biological properties, procurement and results of 150 massive allografts.

Massive bone allografts from cadavers have been sterilised by gamma-radiation from radioactive cobalt at a dose of 25,000 gray (Gy). The biological effects of radiation are discussed. Human cortical bone showed an acceptable 20% decrease in strength on bending tests after 27,000 Gy irradiation, but higher doses are more damaging and should be avoided. The procurement protocol used at the Cochin Hospital is described, and the importance of dosimetry and record-keeping emphasised. The clinical results of 150 massive bone allografts are reported. The infection rate was low. The evolution of the graft in each type of reconstruction is analysed and appears to be comparable to nonirradiated allografts. Very few complications occurred after composite reconstructions in the lower limb. Pelvic reconstructions had the highest complication rate, but most were not related to the use of the allograft.

[The use of coral in bone surgery. Results following 4 years of utilization]. / Utilisation du corail en chirurgie osseuse. Résultats après 4 ans d'utilisation.

The authors have used Porites coral as a bone substitute in more than 200 patients since 1985, initially for reconstruction after craniotomy or removal of graft from the iliac crest. Encouraging results have prompted wider use. No complications have occurred. The biological properties of coral are described. It is easily available and appears to be a promising bone substitute.