Influence of screw type on obtained contact area and contact force in a cadaveric subtalar arthrodesis model

The purpose of this study was to compare the compression effect of the 7.0-AO screw and the 6.5 mm Ideal Compression Screw (I.CO.S.) screw in an in vitro subtalar arthodesis model. Six fresh-frozen, human cadaver foot specimens were obtained for analysis. The subtalar joint was opened laterally without affecting the articular surfaces. ATekscan 5051 sensor with a maximum pressure of 250 PSI and a sensel-density of 62 sensel/sq-cm was placed into the joint, which allowed for continuous measurement of the contact area and contact forces achieved by one 7.0 AO-screw, and thereafter by one 6.5 I.CO.S.-screw. When tightening the screw, mean contact area increased by 0.21 cm2 for the AO-screw (p<0.05), and by 0.27 cm2 for the I.CO.S.-screw (p>0.05). When comparing the tightened AO-screw and I.CO.S.-screw, mean contact area increased from 1.40 cm2 to 1.97 cm2 (p<0.05). The mean contact force also increased when tightening the screws. This increase was 7.6 N for the AO-screw (p<0.05) and 14.8 N for the I.CO.S.-screw (p>0.05). When comparing the tightened AO-screw and I.CO.S.-screw, mean contact force increased from 54.9 N to 81.7 N (p<0.05). The obtained results have shown that the design of the screw influences the achieved compression force. The superior compression of the I.CO.S.-screw might be explained by the better gripping and additional compression mechanism of its head. The shape of the head of the cannulated AO-screw, in contrast, may be critical to resist against the weak cortical bone of the calcaneus, i.e. it can sink into soft bone resulting in a loss of compression force.     

Comparative physiology and biochemistry of rat and rabbit urinary bladder

OBJECTIVE: To compare directly the biochemistry and contractile responses of rat and rabbit bladder to different stimuli. Materials and methods Sexually mature male New Zealand White rabbits and Sprague Dawley rats were compared. Each bladder was excised while the animal was anaesthetized; longitudinal bladder strips were cut and then mounted in an organ bath. Tension (2 g) was placed on all strips and each underwent field stimulation (FS) for a total of 20 s at 1-32 Hz, 1 ms and 80 V and was exposed to carbachol (100 micromol/L), ATP (2 mmol/L) and KCl (120 mmol/L). The tension was monitored continually using a polygraph and data stored digitally in a computer. The responses to each stimulus were determined as the maximum tension generated, maximum rate of tension generation and duration to a maximum response. The Ca2+- ATPase activity of the rat and rabbit bladder was determined. Bladder pressures were then predicted from the strip data using Laplace's law and compared with published values. RESULTS: Contractile responses (per unit tissue mass) of rat bladder strips were significantly greater than those of rabbit bladder strips at all frequencies of FS and to carbachol, KCl and ATP. The rate of contractile force generated by rat bladder strips in response to all stimuli were significantly greater than that generated by rabbit strips. Rabbit bladder strips took significantly longer to generate maximum tension than did rat bladder strips in response to pharmacological stimuli. In response to FS, rat strips took significantly longer than rabbit strips to generate maximum tension. Although the predicted rat bladder pressures were significantly greater than those for rabbit, the predicted pressures for both the rat and rabbit were significantly lower than the pressure responses of the isolated whole bladder model. The contractile data correlated well with the Ca2+-ATPase activity data; rat bladder had seven times the enzyme activity of rabbit bladder. CONCLUSION: Per unit mass, rat bladder is capable of generating more than five times the tension of rabbit bladder. Similarly, the rate of tension generation by rat bladder is three to five times greater than that by rabbit bladder. The duration to maximum tension generated in response to FS compared with pharmacological stimuli was affected by the inherent difference in the rate of contractile response to electrical activation compared with agents which diffuse through tissue, and by the difference in size between rat and rabbit bladder smooth muscle cells.     

Characterization of binding sites for a GnRH-agonist (buserelin) in human breast cancer biopsies and their distribution in relation to tumor parameters

Summary Gonadotropin-releasing hormone analogs (GnRH-A) have been added to the armentarium in the therapy of hormone-dependent breast cancer in premenopausal women. The effect of chronic GnRH-A-treatment in premenopausal women is based on the suppression of the hypothalamus-pituitary-ovarian axis and the reduction of sex-steroid serum levels. In addition, a number of experimental and clinical data have been accumulated indicating a direct action of GnRH-A on breast cancer cells and tissue. In this study we analyzed 235 human breast cancer biopsies for specific GnRH-A-binding. We demonstrate high affinity GnRH-A binding sites in human breast cancer tissues. The evaluation of clinical data showed no correlation of the level of GnRH-A-binding with classical tumor parameters.     

Thoracoscopic resection of intra- and extralobar pulmonary sequestration in the first 3 months of life

Background

Thoracoscopic techniques have gained increasing acceptance in pediatric surgery, but experience with newborns and small children is limited. To our knowledge, a series of minimally invasive resection of pulmonary sequestration in newborns has not yet been reported in the literature. We report on 5 patients with pulmonary sequestration thoracoscopically.

Methods

From November 2000 to November 2002, 5 patients underwent thoracoscopic resection of pulmonary sequestration. Ages ranged from 4 to 91 days. Two patients had postnatal pulmonary symptoms. Preoperative diagnosis was dubious in 4 children. There were 4 extralobar and 1 intralobar pulmonary sequestrations.

Results

Thoracoscopy was performed with 3-mm instruments and 3 to 5 ports. All procedures were completed successfully. The median duration of the operation was 95 minutes (range, 63-117 minutes), and visualization was excellent. Anomalous blood vessels were clipped and/or ligated. Four patients were extubated immediately after the operation, 1, the day after. The postoperative course was uneventful in all children. At follow-up after 14 months (mean; range, 10-19 months), all patients were free of symptoms and had normal chest x-rays.

Conclusion

Thoracoscopy is feasible for resection of intra- and extralobar pulmonary sequestrations during the first 3 months of life.     

Genetic risk estimation by healthcare professionals

OBJECTIVES: To assess whether healthcare professionals correctly incorporate the relevance of a favourable test outcome in a close relative when determining the level of risk for individuals at risk for Huntington's disease. DESIGN AND SETTING: Survey of clinical geneticists and genetic counsellors from 12 centres of clinical genetics (United Kingdom, 6; The Netherlands, 4; Italy, 1; Australia, 1) in May-June 2002. Participants were asked to assess risk of specific individuals in 10 pedigrees, three of which required use of Bayes' theorem. PARTICIPANTS: 71 clinical geneticists and 41 other healthcare professionals involved in genetic counselling. MAIN OUTCOME MEASURES: Proportion of respondents correctly assessing risk in the three target pedigrees; proportion of respondents who were confident of their estimate. RESULTS: 50%-64% of respondents (for the three targets separately) did not include the favourable test information and incorrectly estimated the risks as being about equal to the prior risks; 77%-91% of these respondents were "sure" or "completely sure" that their estimations were correct. Twenty of the 112 respondents correctly estimated the risks for all three target pedigrees. CONCLUSIONS: Clinical geneticists and genetic counsellors frequently use prior risks in situations where Bayes' theorem should be applied, leading to overestimations of the risk for an individual.     

A comparison of two portable dynamometers in the assessment of shoulder and elbow strength

Objectives To compare the practical applicability and measurement properties of a hand-held dynamometer (MicroFET2^®) and a fixed dynamometer (Isobex2.1^®) in determining isometric strength of the shoulder and elbow.Design Muscle strength in four directions (glenohumeral abduction, external rotation and elevation and elbow flexion) was measured using both instruments by two examiners. The assessments were repeated by one of the examiners 3 days later.Setting Leiden University Medical Center.Participants Twenty healthy volunteers.Main outcome measures Time to complete a set of measurements and discomfort were recorded. To determine intra- and inter-observer reliability, intra-class correlation coefficients (ICCs), limits of agreement and smallest detectable difference were computed.Results The time to complete a set of measurements was significantly shorter for the hand-held dynamometer than for the fixed dynamometer in both examiners. The number of subjects reporting discomfort was similar with the two dynamometers. Except for glenohumeral abduction, the forces measured using the hand-held dynamometer were significantly higher than those when using the fixed dynamometer in both examiners. The intra- and inter-observer ICCs for the four directions ranged from 0.82 to 0.98 for both dynamometers. However, the mean differences between replications and the wide limits of agreement suggest substantial bias and variability. For example, for the measurement of shoulder abduction with the fixed dynamometer by one tester (190 N), the results suggest that on 95% of occasions the second tester's measurement would be between 158 and 275 N.Conclusions Although time taken and discomfort should be considered in the selection of dynamometers, due consideration should be given to the significant differences in absolute results. Neither the dynamometers nor the testers can be considered interchangeable. Both the intra- and inter-observer reliability of the two dynamometers were similar, yet both demonstrated systematic bias and variability in the measurements obtained.     

Tarsal navicular stress fractures: radiographic evaluation

Tarsal navicular stress fractures are a potential source of disabling foot pain in physically active individuals. The diagnosis of tarsal navicular stress fracture requires a high index of clinical and radiographic suspicion because the fracture is only rarely evident on routine radiographs or standard tomograms. The radiographic diagnosis of a tarsal navicular stress fracture may require anatomic anteroposterior tomograms or a radionuclide bone scan with plantar views. Radiographic examinations of 23 fractures in 21 patients are evaluated.     

Estrogen as an adjuvant therapy to antipsychotics does not prevent relapse in women suffering from schizophrenia: results of a placebo-controlled double-blind study

The expected therapeutic effect of estrogen as an adjunct treatment to antipsychotics in women suffering from schizophrenia for relapse prevention was to be tested under real-life conditions. A multicenter, randomized, placebo-controlled, double-blind, cross-over study based on an A-B-A-B (and/or B-A-B-A) design was applied. Forty-six hypoestrogenic women with schizophrenia hospitalized for the first time or repeatedly were included in the study. Their average age was 37.9 and they had been suffering from schizophrenia for 8.4 years. During the drug treatment phases, they received a three-phase estrogen-gestagen combination drug (17beta-estradiol+norethisterone acetate) in addition to an antipsychotic drug. Significant effects of the adjuvant hormone replacement therapy on the estradiol levels could be observed, and high and low levels of estradiol prevailed in the active drug and placebo phases, respectively. We did not find any difference either in defined relapse events or in the psychopathology between estradiol replacement and placebo phases. Neither did the required antipsychotic doses or the tolerance data differ between the two phases. Thus, the results of our study do not confirm the hypothesis that a combined estradiol/antipsychotic therapy is superior to an antipsychotic monotherapy for relapse prevention.