Left main stem disease in a patient with Takayasu's arteritis.

Takayasu's arteritis is a chronic vasculitis of unknown aetiology involving the aorta and its main branches, the pulmonary and coronary tree. Women are affected more often than men (80 to 90% of the cases) with an age onset between 10 and 40 years. This case report demonstrates the limitations of exercise testing and stress echocardiography in diagnosing the extent of coronary artery disease in patients with inflammatory disease in the left main stem coronary artery. (Neth Heart J 2007;15:260-2.).

Residual dipolar coupling derived orientational constraints on ligand geometry in a 53 kDa protein-ligand complex.

The geometric relationships between ligands and the functional groups that bind ligands in soluble ligand-protein complexes have traditionally been deduced from distance constraints between pairs of NMR active nuclei spanning the ligand-protein interface. Frequently, the steep inverse distance dependence of the nuclear Overhauser effect (NOE), from which the distance constraints are derived, makes identification of sufficient numbers of constraints difficult. In these cases the ability to supplement NOE-derived information with distance-independent angular information can be very important. Here, the observation of residual dipolar couplings from alpha-methyl mannose bound to mannose binding-protein in a dilute liquid crystalline medium has allowed the determination of a bound ligand's average orientation. The 3-fold rotational symmetry of mannose-binding protein defines its orientational tensor and obviates the need to determine experimentally the protein's average orientation. Through superimposition of ligand and protein orientational tensors we describe the binding geometry of alpha-methyl mannose bound to mannose-binding protein. This new method is of general applicability to the study of ligands bound to proteins, and it is of particular interest when neither X-ray crystallography nor NOE techniques can provide sufficient information to describe binding geometries.

Rapid determination of protein folds using residual dipolar couplings.

Over the next few years, various genome projects will sequence many new genes and yield many new gene products. Many of these products will have no known function and little, if any, sequence homology to existing proteins. There is reason to believe that a rapid determination of a protein fold, even at low resolution, can aid in the identification of function and expedite the determination of structure at higher resolution. Recently devised NMR methods of measuring residual dipolar couplings provide one route to the determination of a fold. They do this by allowing the alignment of previously identified secondary structural elements with respect to each other. When combined with constraints involving loops connecting elements or other short-range experimental distance information, a fold is produced. We illustrate this approach to protein fold determination on (15)N-labeled Eschericia coli acyl carrier protein using a limited set of (15)N-(1)H and (1)H-(1)H dipolar couplings. We also illustrate an approach using a more extended set of heteronuclear couplings on a related protein, (13)C, (15)N-labeled NodF protein from Rhizobium leguminosarum.

Molecular symmetry as an aid to geometry determination in ligand protein complexes.

Dipole-dipole couplings between pairs of spin 12 nuclei, which can be measured from NMR spectra in field-ordered media, offer useful constraints on the orientation of various fragments in molecular systems. However, the orientation of fragments relative to a molecule fixed reference frame is often key to complete structure determination. Here, we demonstrate that the symmetry properties of molecular complexes can aid in the definition of a reference frame. It is shown that a threefold rotational symmetry axis dictates the direction and symmetry of the experimentally determined order tensor for alpha-methyl-mannose in fast exchange among the three symmetry-related binding sites of mannose binding protein. This approach facilitates studies of the geometry of the ligand in the protein-ligand complex and also may provide a novel route to structure determination of a homomultimeric protein.

Variation of molecular alignment as a means of resolving orientational ambiguities in protein structures from dipolar couplings.

Residual dipolar couplings for pairs of proximate magnetic nuclei in macromolecules can easily be measured using high-resolution NMR methods when the molecules are dissolved in dilute liquid crystalline media. The resulting couplings can in principle be used to constrain the relative orientation of molecular fragments in macromolecular systems to build a complete structure. However, determination of relative fragment orientations based on a single set of residual dipolar couplings is inherently hindered by the multi-valued nature of the angular dependence of the dipolar interaction. Even with unlimited dipolar data, this gives rise to a fourfold degeneracy in fragment orientations. In this Communication, we demonstrate a procedure based on an order tensor analysis that completely removes this degeneracy by combining residual dipolar coupling measurements from two alignment media. Application is demonstrated on (15)N-(1)H residual dipolar coupling data acquired on the protein zinc rubredoxin from Clostridium pasteurianum dissolved in two different bicelle media.

Hepatic abscesses in elderly patients mimicking metastatic disease.

BACKGROUND: There is considerable overlap between the clinical presentation and radiological appearances of hepatic abscesses and hepatic metastases. The distinction is important given the treatable nature of hepatic abscesses compared with most forms of metastatic disease and the very high morbidity and mortality associated with untreated or missed pyogenic abscesses. AIMS: The aim of this series of case reports is to illustrate this point by presenting the case histories of three elderly patients whose clinical and radiological findings suggested metastatic liver disease, but who were subsequently proven to have liver abscesses. METHODS: A comprehensive review of the clinical and radiological records of three patients. RESULTS: Ultrasound and computer tomography (CT) imaging in all three cases was suggestive of metastatic liver disease. The liver lesions were subsequently proven to be abscesses either by autopsy, needle aspiration or inspection at open surgery. CONCLUSIONS: Liver abscesses can mimic metastatic deposits. Correlation with the white cell count (WCC) can be very helpful. Fine needle aspiration (FNA) of liver lesions should be undertaken, especially if the WCC is elevated.

Recreational myocardial infarction legacy of the 1990s.

Cocaine is a common drug of abuse with a potential lethal cardiac toxicity. Although cocaine abuse has reached epidemic proportions, the number of cardiovascular complications observed clinically remains low. Over 30% of men and 20% of women between the ages of 26 and 34 have used cocaine at least once. Moreover, more than 30 million Americans have used cocaine at some time, and more than five million are regular abusers. Chest pain is one of the most common reasons for cocaine users to seek medical attention. Over 64,000 patients are evaluated annually for cocaine-related chest pain, of whom more than 57% are admitted to hospital for possible myocardial ischaemia, at an annual cost of more than $83 million.

A usual presentation of an unusual diagnosis.

Chest pain is one of the most common acute medical emergencies and a significant proportion of cases will manifest in one of the acute coronary syndromes. We report a case in which an intermittent non-specific chest pain led to the detection of primary mediastinal large B-cell lymphoma.

Imaging of a non-coronary sinus of Valsalva aneurysm with transthoracic echocardiography and multi-slice computed tomography.

A 46-year-old female with a giant aneurysm of the non-coronary sinus of Valsalva, associated with moderate aortic valve regurgitation, is described. The aneurysm was detected by echocardiography in a patient who was complaining of paroxysmal palpitations. The patient was accepted for aneurysmectomy. In this case report the possible aetiologies and clinical aspects of the aneurysm are reviewed. Treatment and the role of multi-sliced computed tomography (MSCT) in heart disease are discussed.

Role of echocardiography in the diagnosis and management of infective endocarditis.

Infective endocarditis is one of the most common causes of serious infection and carries a high risk of morbidity and mortality. It represents the fourth leading cause of life-threatening infections after urosepsis, pneumonia, and intra-abdominal sepsis. There is still a continuous rise in the incidence of infective endocarditis, with a rate of about 20,000 new cases in the United States alone. This rise in incidence of infective endocarditis is mainly caused by increasing numbers of intravenous drug abusers, patients with artificial valves and elderly patients. In this paper, we will briefly review the crucial role of echocardiography in the diagnosis and management of infective endocarditis.

Coexistence of a bradycardia- and tachycardia-dependent bundle branch block.

Aberrant ventricular conduction is a rare phenomenon as compared with the more frequently occurring antrioventricular conduction disturbances. It leads to widening of the QRS complex, which is either due to a complete or functional block in one of the bundle branches or a block within the intramyocardial conduction system itself. Mechanisms that are potentially involved in the genesis of aberrant ventricular conduction are sudden shortening of cycle length (tachycardia-dependent phase III), antegrade block with retrograde concealed conduction, or bradycardia-dependent block (enhanced phase IV). In this paper, we present a patient with aberrant ventricular conduction with the occurrence of a tachycardia-dependent, as well as a bradycardia-dependent bundle branch block, which is an even rarer phenomenon.

Arrhythmogenic right ventricular dysplasia as a possible cause of sudden cardiac death: a case report and clinical review.

Sudden cardiac death can be described as an unexplained natural death due to a cardiac cause. It occurs within a short period, one hour or less, after onset of symptoms in a person without any prior medical history. Among the many causes of unexplained sudden cardiac death, we would like to specifically discuss arrhythmogenic right ventricular dysplasia as a rare cause in otherwise healthy and usually young individuals.

Massive congenital bidirectional coronary arteriovenous malformation presenting with signs and symptoms of congestive heart failure in an adult: a case report and review of the literature.

Congenital anomalies of the coronary arteries are relatively rare. Mostly asymptomatic, however, some can cause problems, as heart failure, myocardial ischemia, and ventricular arrhythmia, and are associated with risk of complications, such as endocarditis and coronary rupture or sudden death. A case of a 69-year-old man with complaints of tiredness, dyspnea, and palpitation due to coronary artery fistula is presented with a review of the literature.

Staff radiation doses to the lower extremities in interventional radiology.

The purpose of this study was to investigate the radiation doses to the lower extremities in interventional radiology suites and evaluate the benefit of installation of protective lead shielding. After an alarmingly increased dose to the lower extremity in a preliminary study, nine interventional radiologists wore thermoluminescent dosimeters (TLDs) just above the ankle, over a 4-week period. Two different interventional suites were used with Siemens undercouch fluoroscopy systems. A range of procedures was carried out including angiography, embolization, venous access, drainages, and biopsies. A second identical 4-week study was then performed after the installation of a 0.25-mm lead curtain on the working side of each interventional table. Equivalent doses for all nine radiologists were calculated. One radiologist exceeded the monthly dose limit for a Category B worker (12.5 mSv) for both lower extremities before lead shield placement but not afterward. The averages of both lower extremities showed a statistically significant dose reduction of 64% (p < 0.004) after shield placement. The left lower extremity received a higher dose than the right, 6.49 vs. 4.57 mSv, an increase by a factor of 1.42. Interventional radiology is here to stay but the benefits of interventional radiology should never distract us from the important issue of radiation protection. All possible measures should be taken to optimize working conditions for staff. This study showed a significant lower limb extremity dose reduction with the use of a protective lead curtain. This curtain should be used routinely on all C-arm interventional radiologic equipment.