Effects of nail rigidity on fracture healing

The present study was undertaken to assess the effects of the rigidity of nails on the healing of fractures as evaluated by mechanical strength and rate of bone mineralisation. Ten rats supplied biomechanical data at the start of the experiment and another 100 rats were randomly assigned to 5 groups. In 20 rats no intervention was performed, and they served as a reference group of normal values. Thus, 80 rats underwent a standardised partial osteotomy in the left femur diaphysis prior to manual fracture, reaming and intramedullary nailing. One group received rigid steel nails (group 1) and another, cannulated steel nails (group 2). Group 3 received semi-rigid titanium nails and group 4, soft polyethylene nails. Ten rats in each group were evaluated at 6 and 12 weeks after fracture, and radiographs and callus diameter measurements were performed. Dual-energy X-ray absorptiometry (DEXA) of the bones was performed, and the degree of mineralisation in the callus segment, distal diaphysis and total femur was calculated by the scanner. Subsequently, the bones were tested mechanically by a three-point bending test in a Mini Bionix (MTS) testing system. Radiographs revealed clearly visible fractures at 6 weeks in the intervention groups. At 12 weeks there were no signs of bridging callus in group 4, while the other groups presented scarcely visible osteotomies. The callus area in group 4 was significantly larger at both 6 and 12 weeks than in groups 1–3. In these groups there was a significant decrease in callus area between 6 and 12 weeks. Both maximum bending load, bending rigidity and fracture energy increased significantly in groups 1–3 between 6 and 12 weeks, while bending load and fracture energy increased in group 4. At 6 weeks no significant differences were detected between groups 1–3 in mechanical strength. Group 4 had a significantly reduced maximum bending load and fracture energy at 6 and 12 weeks as well as bending rigidity at 12 weeks. At 12 weeks group 3 had a significantly increased maximum bending load and fracture energy compared with groups 1 and 2. Bone mineral count (BMC) in the callus region in group 4 was significantly reduced at both 6 and 12 weeks. BMC in the callus showed no significant differences between groups 1–3, either at 6 or at 12 weeks. BMC in the distal diaphysis was significantly reduced in groups 1 and 4 compared with group 2 at 12 weeks. Bone mineral density (BMD) in the callus region revealed no significant differences between groups 1–3 at 6 weeks, while at 12 weeks BMD was higher in group 3 than in group 1. BMD in the callus region and total femur in group 4 was significantly reduced at 6 weeks. This study demonstrates that diaphyseal fractures treated with titanium nails with a bending rigidity similar to the intact femur have a higher maximum bending load and fracture energy at 12 weeks than both rigidly or softly nailed fractures. BMD in the callus region was also highest after titanium nailing at 12 weeks. BMD in the distal diaphysis and total femur indicates that the degree of stiffness of the nails have little influence on total bone mineralisation at 12 weeks.     

2-mercaptopropionate,a novel metabolite formed during treatment with 2-mercaptopropionyl-glycine in cystinuria

Summary A new acid thiol, 2-mercaptopropionate, has been identified by GC-MS in urine from cystinuric patients on treatment with 2-mercaptopropionylglycine. The amount excreted was 50–300 µmol/24 h and it was correlated with the oral dose of 2-mercaptopropionyl-glycine. The observation may be of clinical importance as the metabolite could be a potential hazard in oxidation of fatty acids.     

Antibodies against 5-hydroxymethyl-2'-deoxyuridine are associated with lifestyle factors and GSTM1 genotype: a report from the Malm? Diet and Cancer cohort.

Plasma autoantibodies (aAbs) against the oxidized DNA base derivative 5-hydroxymethyl-2'-deoxyuridine (5-HMdU) are potential biomarkers of cancer risk and oxidative stress. We examined their association with a number of cancer risk factors: smoking, alcohol habits, body fatness, and absence of the glutathione S-transferases M1 and T1 (GSTM1 and GSTT1) in a sample from the population-based Malm? Diet and Cancer cohort (Sweden). This was a cross-sectional study of 264 men and 280 women, 46-67 years of age. Anti-5-HMdU aAb concentration was determined by an ELISA. Data on tobacco exposure were collected through a questionnaire. Alcohol consumption was estimated by a modified diet history method. Body fatness was assessed by a bioimpedance method. The absence or presence of genes coding for GSTM1 and GSTT1 was determined in granulocyte DNA by a multiplex PCR technique. aAb titers were significantly greater in those with high alcohol consumption. Current smokers lacking GSTM1, particularly men, had greater aAb titers compared with nonsmokers or persons expressing GSTM1. Body fatness was inversely associated with antibody titers in men. GSTT1 genotype was not associated with aAb titers. Overall, women had higher aAb titers than men. Adjustment for potential confounders (history of chronic diseases, anti-inflammatory medication, and season of blood sampling) did not change the results. Our study shows that a high alcohol consumption, smoking in combination with lack of GSTM1, and low body fatness (in men) is associated with high titers of anti-5-HMdU aAbs in this population.     

High-density lipoprotein subfractions,apolipoproteins and antipyrine clearance in normal subjects

Summary Serum high density lipoprotein (HDL) subfractions HDL₂ and HDL₃, apolipoproteins, and plasma antipyrine clearance (AP-CL) rate, an index of liver microsomal enzyme activity, were determined in 21 healthy subjects. High HDL cholesterol and HDL₂ cholesterol concentrations and HDL cholesterol/cholesterol and HDL₂/HDL₃ cholesterol ratios were associated with high AP-CL. Phenobarbital enhanced antipyrine elimination and increased the apolipoprotein A-I/A-II ratio. Subjects who had high AP-CL had a more antiatherogenic HDL subfraction and apolipoprotein profile than those with low AP-CL.     

Hip fracture incidence before and after the fluoridation of the public water supply, Rochester, Minnesota.

Recent ecological comparison studies have suggested a positive association between fluoridation and hip fracture. Using data from the Rochester Epidemiology Project, we found the incidence of hip fracture for the 10 years before the fluoridation of the Rochester, Minn, public water supply was 484 per 100,000, compared with 450 per 100,000 in the following 10 years. When the effects of calendar time and age were controlled for, the relative risk associated with fluoridation was 0.63. These ecologic trend data suggest that the fluoridation of public water supplies is not associated with an immediate increase in rates of hip fracture. Further studies of this association at the individual level are clearly required before public policy decisions can be made.     

Cooking fuel smoke and respiratory symptoms among women in low-income areas in Maputo.

The association between exposure to air pollution from cooking fuels and health aspects was studied in Maputo. Mozambique. Almost 1200 randomly selected women residing in the suburbs of Maputo were interviewed and 218 were monitored for air pollution. The fuels most commonly used were wood, charcoal, electricity, and liquified petroleum gas (LPG). Wood users were exposed to significantly higher levels of particulate pollution during cooking time (1200 micrograms/m3) than charcoal users (540 micrograms/m3) and users of modern fuels (LPG and electricity) (200-380 micrograms/m3). Wood users were found to have significantly more cough symptoms than other groups. This association remained significant when controlling for a large number of environmental variables. There was no difference in cough symptoms between charcoal users and users of modern fuels. Other respiratory symptoms such as dyspnea, wheezing, and inhalation and exhalation difficulties were not associated with wood use. Reducing wood use would likely improve acute respiratory health effects in wood users and possibly improve the ambient air pollution conditions in Maputo. To reduce the health impact of wood smoke exposure, it appears that the least costly and quickest method would be to encourage charcoal use to a greater extent, although high carbon monoxide levels would have to be addressed. Turning to modern fuels is beyond the means of most these households in the short term and could not be shown to be more effective.     

Facilitation of ethanol consumption by intracerebroventricular infusions of corticosterone

Male Wistar rats bearing intracerebroventricular (ICV) cannulae and with simultaneous access to 6% ethanol and water were subjected to adrenalectomy (ADX) or sham surgery. ADX decreased ethanol intake. Starting a few days later, the animals received ICV infusions with 100 μg corticosterone acetate (CORT) with 2-to 3-day intervals for 2 weeks. ICV CORT, but not SC CORT at the same dose, restored ethanol consumption in ADX rats to preoperative levels, whereas vehicle infusions (propylene, glycol) did not. Adrenally intact animals, which normally consumed moderate amounts of ethanol (≈0.5 g/kg per day), also showed a robust effect of ICV infusions of CORT, whereas this facilitatory effect was not observed in high consumers (≈3.0 g/kg per day). The suppressive effect of ADX on ethanol intake was not reproduced by concurrent and repeated ICV infusions of intracellular mineralocorticoid (RU 28318) and glucocorticoid (mifepristone) receptor blockers. It is concluded that CORT stimulates alcohol consumption by acting in the brain, probably by way of neuronal membrane mechanisms.