Stress analyses of glenoid component designs

Metal backing of glenoid components for total shoulder replacements and the use of bony ingrowth surfaces on these components have recently been introduced. In this study, finite element analyses were performed to determine the stress fields in the natural glenoid and to calculate the change in bone stresses after implantation of glenoid components of various designs. The effects of metal backing, keel geometry, and superior constraint on bone stresses indicate that stress distributions on the natural glenoid corresponded to bone morphology. Metal-backing the glenoid component may cause slight improvement in stress transfer to cortical bone. Altered fin geometry better stabilized the glenoid component. Superior restraints on the component intending to prevent subluxation increase stresses and may cause earlier loosening than encountered with unconstrained components.     

Germline mutations in the neurofibromatosis type 2 tumour suppressor gene

The recent identification of the NF2 tumour suppressor genehas enabled large scale screening for pathological mutationsin the gene. We have sought germline mutations In the NF2 geneby SSCP and heteroduplex analysis of cDNA and genomic DNA samplesfollowed by cloning and sequencing of mutant alleles. In thepresent report we describe 11 putative pathological mutations,including five nonsense mutations, three short insertions ordeletions cauing frameshifts and three missense mutations. Moststop mutations and frameshift mutations were found In Individualsexpressing a severe phenotype while one of the three missensemutations was associated with a mild phenotype. Four unrelatedNF2 patients of the 93 tested were found to have identical nonsensemutations caused by a C to T transition (C169) in a CpG dinucleotide,which is a potential mutational hotspot in the NF2 tumour suppressorgene.     

Aggressive angiomyxoma with gastrointestinal communication: a case report

We report the imaging findings of an abdominal aggressive angiomyxoma, which communicated with the gastrointestinal tract. The literature on this rare tumor is reviewed.     

Stress injury of the distal radial growth plate

We report 21 cases of stress injury of the distal radial growth plate-occurring in gymnasts before skeletal maturity. The injury appears to be caused by inability of the growth plate to withstand rotational and compressive forces. Our observations have confirmed that the skeletal age of gymnasts is retarded, which increases the length of time during which the epiphysis is at risk of damage.     

Are current processes for nuclear emergency management in Europe adequate?

We describe the results of process mapping of nuclear emergency management procedures in four European countries. We find clear differences and explore these in relation to their suitability for building a shared understanding across the emergency management team of the evolving situation and a balanced appreciation of the uncertainties. Our findings indicate that there are some issues that cause concern in that the procedures may run smoothly and efficiently but they may also risk underestimating uncertainty or ignore key issues that have only been identified by a minority of experts or models. We are concerned that they do not facilitate the building of shared mental models that the literature such as that on highly reliable organisations has shown is important.     

Cardioselectivity of alpha-tocopherol analogues, with free radical scavenger activity, in the rat.

MDL74270 (6-acetyloxy-3,4-dihydro-N,N,N,2,5,7, 8-heptamethyl-2H-1-benzopyran-2-ethanaminium, 4-methylbenzenesulfonate) is a quaternary amine analogue of alpha-tocopherol with free radical scavenger properties. Rats were injected iv with [14C]MDL74270 (0.91 mg/kg), and whole blood and heart tissue were sampled. Five min after drug, the heart tissue/blood ratio (T/B) of radioactivity was 3.5, whereas at 1 hr it was 20.1 and remained at this value up to at least 6 hr. After iv administration the t 1/2 of radioactivity in blood was 6.3 hr, but po blood levels could not be quantified. The 0- to 96-hr urinary elimination of radioactivity was 39.9 +/- 5.7% of the dose after iv and only 1.2 +/- 0.4% after po administration, conversely, 44.7 +/- 5.2% was excreted in feces after iv and 79.1 +/- 17.4% after po administration. These results confirmed poor oral absorption of the compound. Tissue distribution of [14C]MDL74270 was compared with that of its tertiary amine analogue [14C]MDL74366 in rat heart, skeletal muscle, brain, and whole blood, after iv administration (1 mg/kg). The heart T/B was above 20, 1-6 hr after [14C]MDL74270, whereas it was less than 2 after [14C]MDL74366. Over the 1- to 6-hr time interval, skeletal muscle T/B varied from 1.8 to 5 compared with 1.5 to 0.6 for [14C] MDL74366. Brain T/B was higher after the tertiary amine compound. Results showed marked cardioselectivity of radioactivity after [14C] MDL74270. Differential centrifugation of heart homogenates showed that radioactivity was equally distributed between the major subcellular fractions studied.(ABSTRACT TRUNCATED AT 250 WORDS)     

The relationship of the transcutaneous oxygen tension, pulse waves and systolic pressures to the risk for limb amputation in patients with peripheral arterial disease and skin ulcers or gangrene.

AIM: Our aim was to determine how the risk associated with presence of low transcutaneous oxygen tension (tcPO2) for subsequent major amputation in patients with skin ulcers or gangrene and peripheral arterial disease, compares with the risks associated with low peripheral pressures and low amplitude of pulse waves. Secondly, we determined whether combination of measurements of oxygen tension with that of the pressures or pulse wave amplitude predicts amputation better than pressure, wave or oxygen tension measurements alone. METHODS: Measurements were carried out to obtain foot tcPO2, ankle and toe pressures, pressure indices, and toe pulse wave amplitude in 75 limbs with skin lesions and arterial disease of 66 patients referred to the vascular laboratory. These variables were related to the risk of a subsequent major amputation during a median time of 4.2 years, using Cox proportional hazards model. RESULTS: Low oxygen tension was associated with increased risk of amputation (relative risks 2.16 and 2.55 for tcPO2 < or = 10 mmHg and < or = 20 mmHg, respectively, P<0.05; relative risk 2.22 for tcPO2 < or = 30 mmHg, P=0.07). The relative risks associated with cutoff values of ankle and toe pressures and pressure indices varied from 2.53 (toe < or = 20 mmHg, P<0.05) to 5.83 (ankle < or = 50 mmHg, P<0.001) and the relative risk associated with low wave amplitude (< or = 4 mm) was 3.41, P<0.01. The cutoff values of tcPO2 became insignificant when included in the models together with each pressure variable or pulse amplitude separately. In contrast, wave amplitude remained significantly associated with increased risk of amputation after controlling for each pressure variable (P<0.05). CONCLUSIONS: TcPO2 < or = 10 mmHg and < or = 20 mmHg are related significantly to increased risk of amputation in patients with skin lesions and arterial disease, but these relative risks are similar in magnitude or smaller than those associated with low cutoff values of pressures, pressure indices or pulse wave amplitude. Low wave amplitude does provide significant information in addition to peripheral pressures with respect to the risk of amputation. On the other hand, low tcPO2 does not provide significant information in addition to peripheral pressures or pulse wave amplitude.