Superior dislocation of the patella: a pathognomonic finding and review of literature.

A 59-year-old woman with a painful right knee that became locked in extension after a trivial trauma was seen at the emergency room. This was caused by unloaded hyperextension in bed. She was diagnosed with a superior dislocation of the patella. A closed reduction was performed, but a recurrent episode was seen within a week. An arthroscopy was performed, in which the causative osteophytes were removed. In the 12-month follow-up after treatment, no recurrence was seen. A superior dislocation of the patella is caused by patellofemoral osteophytes that interlock. This can cause a degenerative knee to become locked in extension. Beside interlocking osteophytes of the patella and the distal femur, the superior part of the patella is tilted away from the femur. This is caused by the pull of the patella tendon and the simultaneous relaxation of the quadriceps tendon. This is a pathognomonic finding on radiographs that, to the best of our knowledge, has been identified but not been appreciated as such in previous reports. As illustrated in this report, a superior dislocation of the patella can easily be recognized on physical examination and radiographic imaging alone when familiar with the specific abnormalities. This will reduce unnecessary diagnostic imaging studies and delay in treatment. This case report illustrates a recurrent case of superior dislocation of the patella. We summarize and evaluate previous reports, discuss trauma mechanisms, physical examination, classification, and treatment including recurrent cases. After reading this case report the reader will be able to diagnose a superior dislocation of the patella with near certainty on physical examination and radiographic imaging of the knee alone.

Surface proteomic analysis of osteosarcoma identifies EPHA2 as receptor for targeted drug delivery.

BACKGROUND: Osteosarcoma (OS) is the most common bone tumour in children and adolescents. Despite aggressive therapy regimens, treatment outcomes are unsatisfactory. Targeted delivery of drugs can provide higher effective doses at the site of the tumour, ultimately improving the efficacy of existing therapy. Identification of suitable receptors for drug targeting is an essential step in the design of targeted therapy for OS. METHODS: We conducted a comparative analysis of the surface proteome of human OS cells and osteoblasts using cell surface biotinylation combined with nano-liquid chromatography - tandem mass spectrometry-based proteomics to identify surface proteins specifically upregulated on OS cells. This approach generated an extensive data set from which we selected a candidate to study for its suitability as receptor for targeted treatment delivery to OS. First, surface expression of the ephrin type-A receptor 2 (EPHA2) receptor was confirmed using FACS analysis. Ephrin type-A receptor 2 expression in human tumour tissue was tested using immunohistochemistry. Receptor targeting and internalisation studies were conducted to assess intracellular uptake of targeted modalities via EPHA2. Finally, tissue micro arrays containing cores of human OS tissue were stained using immunohistochemistry and EPHA2 staining was correlated to clinical outcome measures. RESULTS: Using mass spectrometry, a total of 2841 proteins were identified of which 156 were surface proteins significantly upregulated on OS cells compared with human primary osteoblasts. Ephrin type-A receptor 2 was highly upregulated and the most abundant surface protein on OS cells. In addition, EPHA2 was expressed in a vast majority of human OS samples. Ephrin type-A receptor 2 effectively mediates internalisation of targeted adenoviral vectors into OS cells. Patients with EPHA2-positive tumours showed a trend toward inferior overall survival. CONCLUSION: The results presented here suggest that the EPHA2 receptor can be considered an attractive candidate receptor for targeted delivery of therapeutics to OS.

[A painful knee that cannot bend]. / Een pijnlijke knie die niet kan buigen.

A 59-year-old woman was seen at the ER with a painful right knee locked in extension. This was caused by unloaded hyperextension in bed. Interlocking patellofemoral osteophytes and a superior patella dislocation tilted away from the femur were seen on the X-ray, which are both pathognomonic signs of a superior dislocation of the patella.

Transcription of multiple cell wall protein-encoding genes in Saccharomyces cerevisiae is differentially regulated during the cell cycle.

The yeast cell wall consists of an internal skeletal layer and an outside protein layer. The synthesis of both beta-1,3-glucan and chitin, which together from the cell wall skeleton, is cell cycle-regulated. We show here that the expression of five cell wall protein-encoding genes (CWP1, CWP2, SED1, TIP1 and TIR1) is also cell cycle-regulated. TIP1 is expressed in G1 phase, CWP1, CWP2 and TIR1 are expressed in S/G2 phase, and SED1 in M phase. The data suggest that these proteins fulfil distinct functions in the cell wall.

The effect of background illumination on sensitivity to intermittent photic stimulation.

Sensitivity to intermittent photic stimulation (IPS) was tested in 23 photosensitive epileptic subjects under conditions of normal and reduced ambient lighting. Darkening the room to 20 lux did not increase either the incidence of photosensitivity or the effective range of flash frequencies. It is concluded that for routine clinical EEG examination there is no advantage in the current practice of darkening the room during IPS. For exhaustive testing of photosensitivity it is, however, necessary to perform IPS both in light and darkness.

Composition and properties of the sexual agglutinins of the flagellated green alga Chlamydomonas eugametos.

Sexual interaction between gametes of opposite mating type (mt) of the unicellular green alga Chlamydomonas eugametos starts with agglutination of the cells via particular glycoproteins on the flagellar surface. Purification of these socalled agglutinins was achieved by a three-step procedure consisting of, successively, gel filtration, anion-exchange chromatography, and high-performance gel filtration. The amino-acid and sugar compositions of both agglutinins showed a high degree of similarity; the most prominent amino acids were hydroxyproline, serine and glycine, and the main sugars were arabinose and galactose. The carbohydrate portions represented about half of the molecular mass of both agglutinins. Using high-performance gel filtration, a calibration curve was constructed for high-molecular-mass compounds from which the Stokes' radius of the sexual agglutinins could be estimated. The mt (+) agglutinin had a Stokes' radius of 39 nm and a sedimentation coefficient of 9.3 S. From these data its molecular mass was estimated to be 1.2·10(6). The corresponding data for the mt (-) agglutinin were 38 nm, 9.7 S and 1.3·10(6), respectively. The biological activity of both agglutinins was destroyed by mild periodate treatment. Treatment with specific glycosidases had a differential effect on the biological activity of the agglutinins. These observations indicate that carbohydrate side-chains are needed for biological activity and perhaps are responsible for the specifity of the sexual agglutinins. A comparison of both agglutinins is given and their possible structure is discussed in relation to their amino-acid and sugar compositions.

Domain conservation in several volvocalean cell wall proteins.

Based on our previous work demonstrating that (SerPro)x epitopes are common to extensin-like cell wall proteins in Chlamydomonas' reinhardtii, we looked for similar proteins in the distantly related species C. eugametos. Using a polyclonal antiserum against a (SerPro)10 oligopeptide, we found distinct sets of stage-specific polypeptides immunoprecipitated from in vitro translations of C. eugametos RNA. Screening of a C. eugametos cDNA expression library with the antiserum led to the isolation of a cDNA (WP6) encoding a (SerPro)x-rich multidomain wall protein. Analysis of a similarly selected cDNA (VSP-3) from a C. reinhardtii cDNA expression library revealed that it also coded for a (SerPro)x-rich multidomain wall protein. The C-terminal rod domains of VSP-3 and WP6 are highly homologous, while the N-terminal domains are dissimilar; however, the N-terminal domain of VSP-3 is homologous to the globular domain of a cell wall protein from Volvox carteri. Exon shuffling might be responsible for this example of domain conservation over 350 million years of volvocalean cell wall protein evolution.

Sex-specific binding and inactivation of agglutination factor in Chlamydomonas eugametos.

Gametes of opposite mating type (mt (+) and mt (-)) of the green alga Chlamydomonas eugametos agglutinate via their flagella as a prelude to sexual fusion. To quantitate sexual agglutination, an in vitro assay has been developed using (35)S-labeled flagella and the isolated mt (-)agglutination factor. It is shown that not only isolated flagella, but also the mt (-)agglutination factor rapidly bind to the flagella of intact gametes of the opposite mating type. This confirms the role of the mt (-)agglutination factor in determining the sexual agglutinability of mt (-)gametes. As a function of binding, the agglutinative power of the flagella of both mating types is destroyed by a temperature-sensitive process. Likewise, the mt (-)agglutination factor can be completely inactivated.

The contribution of the O-glycosylated protein Pir2p/Hsp150 to the construction of the yeast cell wall in wild-type cells and beta 1,6-glucan-deficient mutants.

The cell wall of yeast contains a major structural unit, consisting of a cell wall protein (CWP) attached via a glycosylphosphatidylinositol (GPI)-derived structure to beta 1,6-glucan, which is linked in turn to beta 1, 3-glucan. When isolated cells walls were digested with beta 1,6-glucanase, 16% of all CWPs remained insoluble, suggesting an alternative linkage between CWPs and structural cell wall components that does not involve beta 1,6-glucan. The beta 1,6-glucanase-resistant protein fraction contained the recently identified GPI-lacking, O-glycosylated Pir-CWPs, including Pir2p/Hsp150. Evidence is presented that Pir2p/Hsp150 is attached to beta 1,3-glucan through an alkali-sensitive linkage, without beta 1,6-glucan as an interconnecting moiety. In beta 1,6-glucan-deficient mutants, the beta 1,6-glucanase-resistant protein fraction increased from 16% to over 80%. This was accompanied by increased incorporation of Pir2p/Hsp150. It is argued that this is part of a more general compensatory mechanism in response to cell wall weakening caused by low levels of beta 1,6-glucan.