Imaging tumors of the patella

BACKGROUND

Patellar tumors are rare; only a few series have been described in the literature and radiographic diagnosis can be challenging. We reviewed all patellar tumors at one institution and reviewed the literature.

MATERIALS AND METHODS

In an evaluation of the database at one institution from 1916 to 2009, 23,000 bone tumors were found. Of these, 41 involved the patella. All had imaging studies and microscopic diagnostic confirmation. All medical records, imaging studies, and pathology were reviewed.

RESULTS

There were 15 females and 26 males, ranging from 8 to 68 years old (average 30). There were 30 benign tumors; eight giant cell tumors, eight chondroblastomas, seven osteoid osteomas, two aneurysmal bone cysts, two ganglions, one each of chondroma, exostosis, and hemangioma. There were 11 malignant tumors: five hemangioendotheliomas, three metastases, one lymphoma, one plasmacytoma, and one angiosarcoma.

CONCLUSION

Patellar tumors are rare and usually benign. As the patella is an apophysis, the most frequent lesions are giant cell tumor in the adult and chondroblastoma in children. Osteoid osteomas were frequent in our series and easily diagnosed. Metastases are the most frequent malignant diagnoses in the literature; in our series malignant vascular tumors were more common. These lesions are often easily analyzed on radiographs. CT and MR define better the cortex, soft tissue extension, and fluid levels. This study presents the imaging patterns of the more common patellar tumors in order to help the radiologist when confronted with a lesion in this location.

Novel POMGNT1 point mutations and intragenic rearrangements associated with muscle-eye-brain disease

Congenital muscular dystrophies due to defects in genes encoding proteins involved in α-dystroglycan (α-DG) glycosylation are a heterogeneous group of muscle disorders variably associated with central nervous system and eye abnormalities. One of the more severe is muscle-eye-brain disease (MEB). Mutations in genes coding for proven or putative glycosyltransferases (POMT1, POMT2, POMGnT1, fukutin, FKRP, and LARGE), the DPM3 gene encoding a DOL-P-Man synthase subunit, and the DAG1 gene encoding α-dystroglycan, have been associated with altered α-DG glycosylation.

We report new POMGnT1 mutations and evaluate protein expression in 3 patients and 2 foetuses with variably severe MEB features. We identify two new point mutations (c.643 C > T, c.1863delC), one new intragenic rearrangement (deletion of exons 2–8), and a new intron retention (between exons 21 and 22) resulting from a known point mutation c.1895 + 1 G > T. Our study provides further evidence that rearrangements of the POMGnT1 gene are relatively common. Importantly, if heterozygous, they can be missed on standard genomic DNA sequencing. POMGNT1 protein analysis in 3 patients showed that the severity of the phenotype does not correlate with protein expression. Cerebral MRI is important for identifying MEB and α-dystroglycanopathy phenotypes in children and foetuses, and hence for directing the genetic analysis.

Single-molecule mechanical unfolding of amyloidogenic beta2-microglobulin: the force-spectroscopy approach

The recombinant production of a novel chimeric polyprotein is described. The new protein contains either wild-type beta(2)-microglobulin (beta(2)m) or its truncated variant (DeltaN6 beta(2)m) (see picture). Structural characterization is achieved by means of single-molecule force spectroscopy studies of specific beta(2)m regions which could be involved in amyloidogenesis.

Micro/Nanoscale Parallel Patterning of Functional Biomolecules, Organic Fluorophores and Colloidal Nanocrystals

We describe the design and optimization of a reliable strategy that combines self-assembly and lithographic techniques, leading to very precise micro-/nanopositioning of biomolecules for the realization of micro- and nanoarrays of functional DNA and antibodies. Moreover, based on the covalent immobilization of stable and versatile SAMs of programmable chemical reactivity, this approach constitutes a general platform for the parallel site-specific deposition of a wide range of molecules such as organic fluorophores and water-soluble colloidal nanocrystals. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11671-009-9386-7) contains supplementary material, which is available to authorized users.

Exploring local flexibility/rigidity in psychrophilic and mesophilic carbonic anhydrases

Molecular flexibility and rigidity are required to determine the function and specificity of protein molecules. Some psychrophilic enzymes demonstrate a higher catalytic efficiency at low temperatures, compared to the efficiency demonstrated by their meso/thermophilic homologous. The emerging picture suggests that such enzymes have an improved flexibility of the structural catalytic components, whereas other protein regions far from functional sites may be even more rigid than those of their mesophilic counterparts. To gain a deeper insight in the analysis of the activity-flexibility/rigidity relationship in protein structure, psychrophilic carbonic anhydrase of the Antarctic teleost Chionodraco hamatus has been compared with carbonic anhydrase II of Bos taurus through fluorescence studies, three-dimensional modeling, and activity analyses. Data demonstrated that the cold-adapted enzyme exhibits an increased catalytic efficiency at low and moderate temperatures and, more interestingly, a local flexibility in the region that controls the correct folding of the catalytic architecture, as well as a rigidity in the hydrophobic core. The opposite result was observed in the mesophilic counterpart. These results suggest a clear relationship between the activity and the presence of flexible and rigid protein substructures that may be useful in rational molecular and drug design of a class of enzymes playing a key role in pathologic processes.

Real-time PCR in a plastic chip based on solid state FRET

We show a novel solid state optical detection platform, integrated in a plastic biochip, based on colloidal nanocrystal FRET donors. The approach exploits a "smart" polymeric layer with both optical and biorecognition properties that allows real-time monitoring of biomolecular interactions and quantitative analyses of real-time PCR. The proposed strategy, demonstrated here for DNA detection, may open interesting perspectives for a wide range of applications, such as for proteomic studies.

Molecular characterization of 6 unrelated Italian patients with 5alpha-reductase type 2 deficiency

Steroid 5alpha-reductase (5alphaR) deficiency (OMIM number #264600) is a rare 46,XY disorder of sex differentiation caused by mutations in the 5alphaR type 2 gene (SRD5A2) resulting in dihydrotestosterone deficiency during fetal development. We report on the analysis of the SRD5A2 gene in 6 unrelated 46,XY Italian patients with external genitalia morphology ranging from predominantly female to nearly completely male. Three subjects were seen and assessed at birth, 1 patient was referred to us before puberty, and 2 at postpubertal age. Six different causative mutations (5 missense and 1 nonsense) and a rare polymorphism were identified. Four patients presented homozygous single-base substitutions. These SRD5A2 mutations were located in exon 2 (variant Cys133Gly), exon 4 (Gly196Ser and Ala207Asp) and exon 5 (Tyr235Phe). A fifth subject was a compound heterozygote who carried a nonsense mutation in exon 1 (Trp53X) and a second SRD5A2 alteration in exon 5 (Tyr235Phe). The final patient presented a mutation in only 1 allele (Gly34Trp) together with the Ala49Thr variant. The molecular characterization of these patients made it possible to identify novel mutations and to confirm, before gender assignment or any surgical approach, the suspected 5alphaR deficiency in 2 newborns, 1 of whom had inconclusive hormonal data. 5alphaR deficiency in subjects without parental consanguinity and the presence of compound heterozygotic patients suggest that SRD5A2 mutations carrier frequency may be higher than previously thought.

Metal-enhanced fluorescence of colloidal nanocrystals with nanoscale control

Engineering the spectral properties of fluorophores, such as the enhancement of luminescence intensity, can be achieved through coupling with surface plasmons in metallic nanostructures. This process, referred to as metal-enhanced fluorescence, offers promise for a range of applications, including LEDs, sensor technology, microarrays and single-molecule studies. It becomes even more appealing when applied to colloidal semiconductor nanocrystals, which exhibit size-dependent optical properties, have high photochemical stability, and are characterized by broad excitation spectra and narrow emission bands. Other approaches have relied upon the coupling of fluorophores (typically organic dyes) to random distributions of metallic nanoparticles or nanoscale roughness in metallic films. Here, we develop a new strategy based on the highly reproducible fabrication of ordered arrays of gold nanostructures coupled to CdSe/ZnS nanocrystals dispersed in a polymer blend. We demonstrate the possibility of obtaining precise control and a high spatial selectivity of the fluorescence enhancement process.