Increased signal in the proximal patellar tendon: normal or pathologic?

OBJECTIVE

To determine the clinical significance of T2 signal hyperintensity in the proximal patellar tendon seen on MRI of the knee.

MATERIALS AND METHODS

MRIs of 100 patients who underwent MRI of the knee between 1 May 2018 and 15 July 2018 were retrospectively evaluated. All examinations were performed on 3-Tesla MRI scanners with a dedicated knee coil and in accordance with our institution's standard knee MRI protocol. The presence of increased T2 signal was assessed on both sagittal and axial T2-weighted fat-saturated images. The amount of increased signal in the proximal patellar tendon on T2-weighted images was characterized as: none, mild, moderate, or severe. A corresponding chart review of the referring physicians' notes was performed to determine the presence of clinical symptoms of patellar tendinopathy. Patellar tendinopathy was considered present if the clinical notes described tenderness on palpation of the inferior patellar pole, infrapatellar tenderness, or patellar tendinosis/tendinitis.

RESULTS

The majority (66%) of knee MRIs demonstrated the presence of increased T2 signal in the proximal patellar tendon. Only 4.5% of these patients had associated clinical findings of patellar tendinopathy.

CONCLUSION

Although increased T2 signal in the proximal patellar tendon is a common finding, only in rare cases are there associated clinical symptoms. Thus, increased T2 signal in the proximal patellar tendon may not be a pathological finding in the absence of clinical findings of patellar tendinopathy.

Elbow Arthroplasty: From Normal to Failure

Total elbow arthroplasty is currently an established surgical treatment for several pathologies of the elbow. Although initially used primarily in the treatment of rheumatoid arthritis, indications for total elbow arthroplasty have expanded and now include trauma, primary and secondary osteoarthritis, fracture nonunion, and following neoplasm resection. Desired outcomes of elbow arthroplasty include decreasing patient pain, restoration of function and mobility, and prevention of or treatment for instability. In comparison with total elbow arthroplasty, radial head replacements are most commonly performed following trauma. An additional technique, capitellar resurfacing arthroplasty, was developed in an effort to prevent early-onset osteoarthritis secondary to altered elbow biomechanics following radial head replacement. Complications of these surgeries include loosening, fracture, instability and dissociation, bushing wear, and particle disease.

Outcomes of Demineralized Bone Matrix Enriched with Concentrated Bone Marrow Aspirate in Lumbar Fusion

BACKGROUND

Multiple studies have demonstrated that a significant amount of variability exists in various demineralized bone matrix (DBM) formulations, which casts doubts on its reliability in consistently promoting fusion. Bone marrow aspirate (BMA) is a cellular based graft that contains mesenchymal stem cells (MSCs) and growth factors can confer osteogenic and osteoinductive potential to DBM. The goal of this study was to describe the outcome of DBM enriched with concentrated BMA in patients undergoing combined lumbar interbody and posterolateral fusion.

METHODS

Eighty patients with a minimum of 12 months of follow-up were evaluated. Fusion and rates of complication were evaluated. Functional outcomes were assessed based on the modified Odom's criteria. Multiple logistic regression analysis was used to examine the effects of independent variables on fusion outcome.

RESULTS

The overall rate of solid fusion (i.e patients with both solid posterolateral and interbody fusion) was 81.3% (65/80). Specifically, the radiographic evidence of solid posterolateral and interbody fusions were 81.3% (65/80) and 92.5% (74/80), respectively. Seven (8.75%) patients developed hardware-related complications, 2 (2.5%) patients developed a postoperative infection and 2 (2.5%) patients developed clinical pseudarthrosis. Charlson comorbidity index (CCI) scores of 3 and 4 were associated with non-solid unions (CCI-3, p = 0.048; CCI-4, p = 0.03). Excellent or good outcomes were achieved in 58 (72.5%) patients.

CONCLUSIONS

Patients undergoing lumbar fusion using an enriched bone graft containing concentrated BMA added to DBM can achieve successful fusion with relatively low complications and good functional outcomes. Despite these findings, more studies with higher level of evidence are needed to better understand the efficacy of this promising graft option.

Treatments for Kienböck disease: what the radiologist needs to know

The etiology of Kienböck disease, or avascular necrosis of the lunate, is controversial, and there are a myriad of treatments aimed at correcting the various hypothesized pathologies. Interventions to reduce mechanical stress on the lunate have been used for decades, including radial osteotomy with or without radial shortening, ulnar lengthening and metaphyseal core decompression procedures. However, these procedures require preservation of lunate architecture. Newer procedures to revascularize the lunate bone have emerged in the last 10 years, such as pedicled corticoperiosteal vascularized bone grafting. Once there is collapse of the radiocarpal joint or midcarpal arthrosis, the conventional treatments have included proximal row carpectomy and complete or partial wrist joint arthrodesis. Newer salvage procedures such as lunate excision with autologous or synthetic interposition grafts are now being used when possible. As this disease is relatively rare, radiologists may not be familiar with the expected post-operative radiologic findings and complications, especially of the newer treatments. The goals of this paper are to review the available treatment options and their expected appearance on postoperative imaging, with discussion of possible complications when appropriate.

Implementing the International Health Regulations (2005) in Europe

The adoption of the International Health Regulations (2005) (also referred to as IHR(2005) or the revised Regulations) provides a remarkable new legal tool for the protection of international public health. Upon entry into force on 15 June 2007, Article 2 (‘Purpose and scope‘) provides that the overall focus of the efforts of States Parties (and World Health Organization's efforts) under the revised Regulations will be to prevent, protect against, control and provide a public health response to the international spread of disease in ways that are commensurate with the public health risks and which avoid unnecessary interference with international traffic. Health measures under the revised Regulations will be implemented with respect for travellers’ human rights, with several specific new requirements in this area. To comply with the IHR (2005), States Parties (WHO member states that will be bound by the IHR(2005)) will have to have core public health capacities in disease surveillance and response, as well as additional capacities at designated international ports, airports and land crossings. This unique collective commitment will require close collaboration between WHO and the States Parties, but also intersectoral collaboration within the States themselves, including collaboration among different administrative or governmental levels, a particular issue for federal states, and horizontally across ministries and disciplines. Collaboration among States Parties is a key aspect of the revised Regulations, whether among neighbours, or with trading partners, members of regional economic integration organisations or other regional groups, or simply members of the international community. This collaboration is particularly relevant for the Member States of the European Union.

Implementing the International Health Regulations (2005) in Europe

The adoption of the International Health Regulations (2005) (also referred to as IHR(2005) or the revised Regulations) provides a remarkable new legal tool for the protection of international public health. Upon entry into force on 15 June 2007, Article 2 ('Purpose and scope') provides that the overall focus of the efforts of States Parties (and World Health Organization's efforts under the revised Regulations will be to prevent, protect against, control and provide a public health response to the international spread of disease in ways that are commensurate with the public health risks and which avoid unnecessary interference with international traffic. Health measures under the revised Regulations will be implemented with respect for travellers' human rights, with several specific new requirements in this area. To comply with the IHR(2005), States Parties (WHO member states that will be bound by the IHR(2005)) will have to have core public health capacities in disease surveillance and response, as well as additional capacities at designated international ports, airports and land crossings. This unique collective commitment will require close collaboration between WHO and the States Parties, but also intersectoral collaboration within the States themselves, including collaboration among different administrative or governmental levels, a particular issue for federal states, and horizontally across ministries and disciplines. Collaboration among States Parties is a key aspect of the revised Regulations, whether among neighbours, or with trading partners, members of regional economic integration organisations or other regional groups, or simply members of the international community. This collaboration is particularly relevant for the Member States of the European Union.

The role of histidines 26 and 33 in the structural stabilization of cytochrome c

Comparative studies of the importance of the two histidines of rat cytochrome c that are not ligands of the heme iron, for the stability of the protein, were carried out by site-directed mutagenesis. Histidine 26 was substituted by valine and the resulting effects on the stability of the Met-80-sulfur to heme iron bond to changes in pH and temperature, and of the global stability of the protein to unfolding in urea solutions, were measured. It is suggested that the loss of the hydrogen bond between the His-26 imidazole and the backbone amide of Asn-31 caused the observed decreases in local stability; and that, in addition, the elimination of the hydrogen bond between this imidazole and the carbonyl of Pro-44 resulted in an increase of the mobility of the lower loop (residues 41-47) on the right side of the protein and of its distance from the middle loop (residues 26-31), probably leading to greater hydration of the interior right side of the molecule. These changes resulted in a decrease in the global stability of the protein. Further mutation of Asn-52 to Ile led to a total recovery of the wild-type stability of the sulfur-iron bond, and a partial restoration of the global stability of the protein. Substitution of Phe for His-33 did not alter the sulfur-iron bond but caused a pronounced increase in the global stability of the protein. It is suggested that this effect results from hydrophobic interaction of the Phe-33 side chain with the lower loop on the right side of the protein. Such an interaction also explains the observation that the same mutation reversed the loss of global stability caused by substitution of Val to His-26, but did not restore the strength of the sulfur-iron bond that this mutation had brought about.

The significance of denaturant titrations of protein stability: a comparison of rat and baker's yeast cytochrome c and their site-directed asparagine-52-to-isoleucine mutants

The residue asparagine-52 of rat cytochrome c and baker's yeast iso-1-cytochrome c was mutated to isoleucine by site-directed mutagenesis, and the unfolding of the wild-type and mutant proteins in urea or guanidinium chloride solutions was studied. Whereas the yeast mutant cytochrome unfolded in 4-7 M urea with a rate constant (k) of 1.7 x 10(-2) s-1, the rat mutant protein unfolded with k = 5.0 x 10(-2) s-1, followed by a slow partial refolding with k = 5.0 x 10(-4) s-1. Denaturant titrations indicated that the mutation increased the stability of the yeast cytochrome by 6.3 kJ (1.5 kcal)/mol, while it decreased that of the rat protein by 11.7 kJ (2.8 kcal)/mol. These results probably reflect structural differences between yeast iso-1 and vertebrate cytochromes c in the vicinity of the Asn-52 side chain.

Foscarnet-resistant herpes simplex virus infection in patients with AIDS

Six human immunodeficiency virus-infected patients had clinical lesions of herpes simplex virus (HSV) type 2 that showed in vitro resistance to foscarnet. In each patient, lesions were unresponsive to foscarnet therapy or developed during daily suppressive foscarnet. Five patients had a history of intermittent or chronic foscarnet use for the management of acyclovir-resistant HSV infection, and 1 was receiving daily foscarnet for suppression of cytomegalovirus retinitis. Seven of 10 foscarnet-resistant isolates from 6 patients were susceptible to acyclovir in vitro, and 1 was of borderline susceptibility. In 3 patients, the administration of acyclovir, either alone or in combination with foscarnet, resulted in healing. Clinically significant resistance to foscarnet may occur in immunosuppressed patients with prior foscarnet exposure. Addition or substitution of acyclovir to foscarnet therapy may be a useful strategy for patients in whom foscarnet resistance is suspected, pending the results of in vitro susceptibility testing.

The reactivity of cytochrome c with soft ligands

The spectral changes caused by binding soft ligands to the cytochrome c iron and their correlation to ligand affinities support the hypothesis that the iron-methionine sulfur bond of this heme protein is enhanced by delocalization of the metal t2g electrons into the empty 3d orbitals of the ligand atom. These findings also explain the unique spectrum of cytochrome c in the far red.

The binding characteristics of the cytochrome c iron

A comparison of the binding properties of myoglobin and cytochrome c shows that the latter, in the reduced state, has an unusually large affinity for ligands, including thioethers. This explains the outstanding stability of the methionine-iron bond of ferrous cytochrome c, and results from the intrinsic ability of the cytochrome c iron to delocalize its electrons into orbitals of the sixth axial ligand.

Isolation and properties of the soluble c-type cytochromes of the dinoflagellate Peridinium cinctum

Four soluble cytochromes of the c type were isolated from the freshwater dinoflagellate Peridinium cinctum collected from Lake Kinneret, Israel. Cytochrome c with alpha-band maximum at 550 nm in the reduced state had a molecular mass of 10,200 Da, pI 7.4, and Em of 278 m V. This cytochrome was active in the respiratory chain of beef heart Keilin-Hartree particles. Cytochrome c-553 had a molecular mass of 13,200 Da, pI 4.9, and Em of 384 m V, and was active in light induced electron transport of Euglena gracilis chloroplast fragments. Cytochrome c-554 had a molecular mass of 13,500 Da, pI 4.4, and Em of 326 m V. This cytochrome was inactive in light induced electron transport but competed with cytochrome c-552 of Euglena in the assay. The acidic cytochrome c-557 was present in very small quantities. The properties of the soluble c-type cytochromes of P. cinctum are compatible with the classification of dinoflagellates as primitive eucaryotes.