Patellofemoral Pain : Where does the pain come from?

My thesis is about patellofemoral pain (PFP), a common knee complaint among physically active young individuals. It is also known as ’anterior knee pain’, ’retropatellar chondropathy’ or more recently suggested ‘theatre or moviegoers knee’. PFP is characterized by retropatellar pain (behind the kneecap) or peripatellar pain (around the kneecap), specifically during knee loading activities, like running, cycling, squatting, stair climbing, and/or during prolonged sitting with the knees flexed in 90 degrees. The majority of people with PFP are treated conservatively with exercise therapy, but the effect of exercise therapy is still unknown. Therefore, this thesis assessed the effects of exercise therapy and aimed to point out the most effective exercise strategy. However, despite the application of a variety of treatment modalities, a substantial group of patients has persistent complaints. The pathophysiology of PFP is considered to be multifactorial, but still widely unknown. Therefore, emphasis has been placed on unraveling the pathophysiology of PFP with advanced MRI techniques. For years it has been suggested that cartilage plays an important role, but this thesis suggests otherwise. Furthermore, an innovative MRI method was developed to study blood perfusion of the patella. It might be that vascular problems are present in patients with knee pain during watching a movie or visiting the theatre in particular. Or maybe, there are no differences between patients and control subjects on MRI, but only differences in pain perception as has been suggested previously......

The Euler Spiral of Rat Whiskers

This paper reports on an analytical study of the intrinsic shapes of 523 whiskers from 15 rats. We show that the variety of whiskers on a rat’s cheek, each of which has different lengths and shapes, can be described by a simple mathematical equation such that each whisker is represented as an interval on the Euler spiral. When all the representative curves of mystacial vibrissae for a single rat are assembled together, they span an interval extending from one coiled domain of the Euler Spiral to the other. We additionally find that each whisker makes nearly the same angle of 47 with the normal to the spherical virtual surface formed by the tips of whiskers, which constitutes the rat’s tactile sensory shroud or ‘search-space’. The implications of the linear curvature model for gaining insight into relationships between growth, form and function are discussed

Obesity-induced chronic inflammation in C57Bl6J mice, a novel risk factor in the progression of renal AA amyloidosis?

Background: Compelling evidence links obesity induced systemic inflammation to the development of chronic kidney disease (CKD). This systemic inflammation may result from exacerbated adipose inflammation. Besides the known detrimental effects of typical pro-inflammatory factors secreted by the adipose tissue (TNF-α, MCP-1 and IL-6) on the kidney, we hypothesize the enhanced obesity-induced secretion of serum amyloid A (SAA), an acute inflammatory protein, to play a key role in aggravating obesity-induced CKD. Methods: Groups of male C57Bl/6J mice (n = 99 in total) were fed a low (10% lard) or high (45% lard) fat diet for a maximum of 52 weeks. Mice were sacrificed after 24, 40 and 52 weeks. Whole blood samples, kidneys and adipose tissues were collected. The development of adipose and renal tissue inflammation was assessed on gene expression and protein level. Adipocytokine levels were measured in plasma samples. Results: A distinct inflammatory phenotype was observed in the adipose tissue of HFD mice prior to renal inflammation, which was associated with an early systemic elevation of TNF-α, leptin and SAA (1A-C). With aging, sclerotic lesions appeared in the kidney, the extent of which was severely aggravated by HFD feeding. Lesions exhibited typical amyloid characteristics (2A) and pathological severity positively correlated with bodyweight (2B). Interestingly, more SAA protein was detected in lesions of HFD mice. Conclusion: Our data suggest a causal link between obesity induced chronic inflammation and AA amyloidosis in C57Bl/6J mice. Though future studies are necessary to prove this causal link and to determine its relevance for the human situation, obesity may hence be considered a risk factor for the development and progression of renal AA amyloidosis in the course of CKD. (Figure Presented)

Patellofemoral alignment and geometry and early signs of osteoarthritis are associated in patellofemoral pain population

Background: Patellofemoral pain (PFP) patients show increased prevalence of patellar malalignment. Structural and alignment abnormalities of the patellofemoral joint (PFJ) may play a role in development of PFP and patellofemoral osteoarthritis (PFOA). Objectives: Evaluating associations of patellofemoral alignment and femoral geometry with bony and cartilaginous abnormalities in PFP patients and healthy control subjects. Methods: Data from a case-control study were used (64 PFP subjects, 70 control subjects, 57% female, age 23.2 (6.4)). Alignment and femoral geometry measu

Quantitative DCE-MRI demonstrates increased blood perfusion in Hoffa’s fat pad signal abnormalities in knee osteoarthritis, but not in patellofemoral pain

Objective: Infrapatellar fat pad (IPFP) fat-suppressed T2 (T2FS) hyperintense regions on MRI are an important imaging feature of knee osteoarthritis (OA) and are thought to represent inflammation. These regions are also common in non-OA subjects, and may not always be linked to inflammation. Our aim was to evaluate quantitative blood perfusion parameters, as surrogate measure of inflammation, within T2FS-hyperintense regions in patients with OA, with patellofemoral pain (PFP) (supposed OA precursor), and control subjects. Methods: Twenty-two knee OA patients, 35 PFP patients and 43 healthy controls were included and underwent MRI, comprising T2 and DCE-MRI sequences. T2FS-hyperintense IPFP regions were delineated and a reference region was drawn in adjacent IPFP tissue with normal signal intensity. After fitting the extended Tofts pharmacokinetic model, quantitative DCE-MRI perfusion parameters were compared between the two regions within subjects in each subgroup, using a paired Wilcoxon signed-rank test. Results: T2FS-hyperintense IPFP regions were present in 16 of 22 (73%) OA patients, 13 of 35 (37%) PFP patients, and 14 of 43 (33%) controls. DCE-MRI perfusion parameters were significantly different between regions with and without a T2FS-hyperintense signal in OA patients, demonstrating higher Ktrans compared to normal IFPF tissue (0.039 min−1 versus 0.025 min−1, p = 0.017) and higher Ve (0.157 versus 0.119, p = 0.010). For PFP patients and controls no significant differences were found. Conclusions: IPFP T2FS-hyperintense regions are associated with higher perfusion in knee OA patients in contrast to identically appearing regions in PFP patients and controls, pointing towards an inflammatory pathogenesis in OA only. Key Points: • Morphologically identical appearing T2FS-hyperintense infrapatellar fat pad regions show different perfusion in healthy subjects, subjects with patellofemoral pain, and subjects with knee osteoarthritis. • Elevated DCE-MRI perfusion parameters within T2FS-hyperintense infrapatellar fat pad regions in patients with osteoarthritis suggest an inflammatory pathogenesis in osteoarthritis, but not in patellofemoral pain and healthy subjects

Предсказание торсионных углов в аминокислотных последовательностях белков на основе байесовской процедуры распознавания на цепях Маркова

Запропоновано процедуру розпізнавання торсіонних кутів, утворених C^α атомами чотирьох сусідніх амінокислотних залишків. Отримана послідовність кутів використовується для побудови просторової структури білка на решітці Z³.Torsion angles defined on C^α atoms of four neighbouring residues are predicted using Bayesian pattern recognition procedure on non-stationary Markov chains. The predicted sequence of torsion angles is used for constructing protein 3-dimensional structure on Z³