Electromyographic investigation of unstable patella before and after its realignment operation

Background:

Patellar dislocations are either due to superolateral contracture of the soft tissue or imbalance of the power between the vastus medialis (VM) and the vastus lateralis (VL). The imbalance of muscle power as an etiology of patellar dislocation has not been studied. Hence, we studied the recurrent, habitual and permanent dislocations of the patella with an electromyogram (EMG) of the vastus medialis, vastus lateralis, and pes anserinus, before and after realignment operations, to document the muscle imbalance and effectiveness of the realignment operation.

Materials and Methods:

An electromyographic investigation was carried out on the vastus medialis and vastus lateralis in nine recurrent, 20 habitual, and 13 permanent dislocations of the patella, before and after their realignment operations. Pes anserinus transposition, which acted as a medial stabilizer of the patella, was also investigated with an EMG study, to understand its role on patellar stability at 0°, 30°, 60°, 90°, 120°, 150°, and full flexion of the knee. The age of the patients varied from nine to 30 (mean 15) years. There were 24 males and 18 females. Twenty-six patellar dislocations were on the right and 16 were on the left side.

Results:

Electromyographic pictures reveal subnormal activity of the vastus medialis in all types of dislocations and similar activities of the vastus lateralis in permanent and habitual dislocations recorded pre operatively, which recovered to almost normal values postoperatively, at the mean one-year follow-up. Pes anserinus, which was used for medial stabilization of the patella after its realignment, maintained normal EMG activity before and after the operation.

Conclusion:

This study is significant for understanding the imbalance of muscle activities in patients with an unstable patella, which can be rectified without recurrence after pes anserinus transposition.     

Selective breeding for extremes in open-field activity of mice entails a differentiation of hippocampal mossy fibers

The brains of mice selectively bred for differential locomotor activity in an open field (DeFrieset al., Behav. Genet. 8:3–13, 1978) were analyzed for selection-dependent changes in the size of synaptic fields at the midseptotemporal level of the hippocampus. Timm-stained areas of all hippocampal fields from both left and right hippocampi were measured on five horizontal sections from the midseptotemporal level. The sample included 25 mice from two replicate lines, each one consisting of a high (HI); a low (LO), and a control line (CTL). The main selection effect was an enlargement of the intrainfrapyramidal mossy fiber (IIP-MF) projection in both HI lines by about 70% compared to LO and CTL mice (p<.0001), while other mossy fiber fields did not show differences. These findings confirm that genetic variations of the IIP-MF projection influence hippocampal processes mediating exploratory activities. This article is part of a M.D. thesis submitted to the Medical Faculty of the University of Zürich by the first author. We are deeply saddened by her untimely death.     

Swimming navigation,open-field activity,and extrapolation behavior of two inbred mouse strains with Robertsonian translocation of chromosomes 8 and 17

Female mice from inbred strains carrying a Robertsonian translocation (nine CBARb and eight C57BL/6Rb) were compared with animals from their respective strains (seven CBA and nine C57BL/6) first in open-field activity (two exposures of 10-min duration), then during 5 days (with six trials each) in Morris' swimming navigation test, and finally, in their ability to extrapolate the future position of a food reward being moved slowly out of their reach. ANOVA (strain and translocation) revealed significant effects of Robertsonian translocations (Rb) in swimming navigation,Rb mice being impaired primarily in the initial phases of acquisition and during the first trials of platform reversal and the impairment being stronger in C57BL/6 mice. In the open field,Rb mice were as active as the normal strains but showed significantly increased path tortuosity and moved slightly faster. In the extrapolation task,Rb mice showed above-chance levels in moving to the target indicated by the disappearance of the stimulus, while normal mice chose at chance levels, but the translocation effects were not statistically significant. These data indicate that telocentric fusion of chromosomes may entail behavioral alterations, perhaps by subtle changes in neurotransmitters or limbic circuitry. The expression of such alterations, however, can be remarkably strain dependent.     

Reducing overdiagnosis by polygenic risk-stratified screening: findings from the Finnish section of the ERSPC

Background:

We derived estimates of overdiagnosis by polygenic risk groups and examined whether polygenic risk-stratified screening for prostate cancer reduces overdiagnosis.

Methods:

We calculated the polygenic risk score based on genotypes of 66 known prostate cancer loci for 4967 men from the Finnish section of the European Randomised Study of Screening for Prostate Cancer. We stratified the 72 072 men in the trial into those with polygenic risk below and above the median. Using a maximum likelihood method based on interval cancers, we estimated the mean sojourn time (MST) and episode sensitivity. For each polygenic risk group, we estimated the proportion of screen-detected cancers that are likely to be overdiagnosed from the difference between the observed and expected number of screen-detected cancers.

Results:

Of the prostate cancers, 74% occurred among men with polygenic risk above population median. The sensitivity was 0.55 (95% confidence interval (CI) 0.45–0.65) and MST 6.3 (95% CI 4.2–8.3) years. The overall overdiagnosis was 42% (95% CI 37–52) of the screen-detected cancers, with 58% (95% CI 54–65) in men with the lower and 37% (95% CI 31–47) in those with higher polygenic risk.

Conclusion:

Targeting screening to men at higher polygenic risk could reduce the proportion of cancers overdiagnosed.     

Arterial remodelling in Fabry disease

Aim : The enzymatic defect in Fabry disease results in the slow systemic deposition of uncleaved glycosphingolipids in the lysosomes of vascular endothelium and smooth muscle cells, leading to ischaemic strokes, cardiomyopathy and renal failure. Whereas it is known that Fabry disease affects small blood vessels, little is known about its effects on peripheral large arteries. We therefore set out to compare parameters of arterial wall structure and function in a cohort of patients with Fabry disease and an age-matched control group. Methods : Large artery phenotype was non-invasively investigated in 21 hemizygous patients with Fabry disease and 24 age-matched male controls. Common carotid and radial artery diameter, intima-media thickness (IMT) and distensibility were determined with high-definition echotracking systems and aplanation tonometry. Results : Patients with Fabry disease had a significant twofold increase in radial artery IMT and distensibility, independent of body surface area, age and mean blood pressure. In both groups, older age at the time of examination was significantly associated with larger radial artery IMT. The relationship between age and radial IMT was 2.3-fold higher in patients with Fabry disease than in controls ( p > 0.01). Carotid IMT was mildly but significantly increased in patients with Fabry disease (+18%), whereas distensibility was unchanged.
Conclusion : This study presents evidence of a major increase in arterial wall thickness and distensibility, measurable at the site of a medium-sized artery, in a cohort of patients with classic Fabry disease.