[Stress fractures of the femoral neck due to step aerobics--case report]. / Stressfraktur des Schenkelhalses durch Step Aerobic-Kasuistik.

With the rising public interest in physical fitness an increasing number of stress reactions of the bone are diagnosed. Commonly known in competitive athletes, they are increasingly seen in recreational sports. Stress reactions of the bone are a disorder between the loading force and the capability to compensate. Stress fractures with displacement of the bone are more rarely diagnosed due to improved diagnostic means. Stress fractures of the medial femoral neck in young athletes are uncommon. We are reporting the case of a beginning tension type stress fracture of the medial femoral neck of a 29 year old female recreational athlete after excessive stepping and step aerobic at a fitness center.

Escherichia coli peptide binding protein OppA has a preference for positively charged peptides.

The Escherichia coli peptide binding protein OppA is an essential component of the oligopeptide transporter Opp. Based on studies on its orthologue from Salmonella typhimurium, it has been proposed that OppA binds peptides between two and five amino acids long, with no apparent sequence selectivity. Here, we studied peptide binding to E. coli OppA directly and show that the protein has an unexpected preference for basic peptides. OppA was expressed in the periplasm, where it bound to available peptides. The protein was purified in complex with tightly bound peptides. The crystal structure (up to 2.0 Å) of OppA liganded with the peptides indicated that the protein has a preference for peptides containing a lysine. Mass spectrometry analysis of the bound peptides showed that peptides between two and five amino acids long bind to the protein and indeed hinted at a preference for positively charged peptides. The preference of OppA for peptides with basic residues, in particular lysines, was corroborated by binding studies with peptides of defined sequence using isothermal titration calorimetry and intrinsic protein fluorescence titration. The protein bound tripeptides and tetrapeptides containing positively charged residues with high affinity, whereas related peptides without lysines/arginines were bound with low affinity. A structure of OppA in an open conformation in the absence of ligands was also determined to 2.0 Å, revealing that the initial binding site displays a negative surface charge, consistent with the observed preference for positively charged peptides. Taken together, E. coli OppA appears to have a preference for basic peptides.

[Paget's disease of the proximal ulna--a rare monostotic manifestation]. / Morbus Paget der proximalen Ulna--eine seltene monostotische Manifestation.

Bone changes of the upper extremity are rare manifestations of the M. Paget disease. Most frequently the disease affects the lower extremities, the pelvis followed by the calvarium and others. The rare asymptomatic, monostotic manifestation of Paget's disease of the left proximal ulnae of a 59 year old woman and the way of diagnosis is described. Symptomatic skeletal lesions are detected by radiological examination, bone scintigraphy reveals asymptomatic lesions. Laboratory tests (Alkaline serum phosphatase, Hydroxyproline in urine) monitor the activity of the disease.