Low-artifact intravascular devices: MR imaging evaluation

Flow-phantom magnetic resonance (MR) imaging, with use of both spin-echo (SE) and gradient-echo (GRE) techniques at 1.5 T, was performed on the percutaneous Greenfield (beta-III titanium alloy [TMA wire]), Amplatz (MP32-N alloy), and Simon nitinol filters and TMA wire facsimiles of the bird's nest, Gunther, new retrievable, and Amplatz vena caval filters. SE imaging allowed detection of thrombi as small as 5 X 5 mm trapped within the percutaneous Greenfield, Simon nitinol, and TMA-wire facsimile filters; with the MP32-N Amplatz filter, a larger volume of thrombus (10 X 20-mm clots) was necessary for clot detection. GRE imaging allowed detection of intraluminal tilting of the percutaneous Greenfield and facsimile Amplatz (TMA-wire) filters. GRE imaging was useful for demonstrating postfilter turbulence due to clots, which was greatest for the Amplatz filter. Imaging of facsimile vascular devices made of tantalum or TMA wire did not cause the severe "black-hole" MR artifacts typical of the stainless-steel devices. SE and GRE imaging were very useful for determining caval patency in two patients with previously placed Mobin-Uddin filters. Noninvasive MR evaluation of blood vessels in the presence of a variety of low-artifact intravascular devices appears feasible.     

Differential expression of CD11b/CD18 (Mo1) and myeloperoxidase genes during myeloid differentiation

During the course of differentiation of early human myeloid cells toward monocytes and granulocytes, cell surface expression of the cell adhesion molecule, CD11b/CD18 (Mo1) increases dramatically and expression of myeloperoxidase (MPO), a bacteriocidal enzyme, decreases markedly. Using the inducible promyelocytic cell line HL-60 as a model, we studied the mRNA expression of these genes. Differentiation of these cells along both a monocytic and a granulocytic pathway demonstrated that the mRNA levels of the two subunits of CD11b/CD18 increased in a pattern temporally and quantitatively similar to the increase in cell surface expression of this heterodimer. In contrast, the expression of MPO mRNA decreased in a temporal and quantitative pattern similar to the known decrease in MPO protein during differentiation, suggesting that regulation of these myeloid-specific proteins may occur at the level of mRNA expression. These findings have important implications with regard to the nature of the block in differentiation in acute nonlymphocytic leukemia and the regulation of myeloid gene expression.     

In Vitro Elution of Daptomycin by a Synthetic Crystallic Semihydrate Form of Calcium Sulfate,Stimulan

A synthetic crystallic semihydrate form of calcium sulfate, Stimulan, was evaluated as a biodegradable carrier for the daily in vitro elution of daptomycin. Daptomycin and Stimulan were admixed at a ratio of 95:5. Elution lasted for 28 days. Eluted concentrations peaked on days 1 and 11, when the mean values were 1,320.1 and 949.2 μg/ml, respectively. The lowest eluted concentration was detected on day 28. These results support the application of the system described in experimental models of osteomyelitis.Chronic osteomyelitis is an infection difficult to treat due both to multidrug resistance of common pathogens and to poor penetration of antibiotics into bone (16). Carriers for local delivery of antimicrobials have been developed, attempting to provide locally high concentrations of antibiotics (5). Some newly developed biodegradable carriers have been shown to be very potent for the eradication of experimental osteomyelitis (6, 7). The semihydrate form of calcium sulfate (CaSO₄), commonly known as plaster of Paris, may be applied as a biodegradable system for local drug delivery. It has been used for decades to fill bone cavities resulting from disease, trauma, or surgery (11). It was recently shown to be potent in vitro for the release of vancomycin, teicoplanin, gentamicin, and clindamycin (15). The antimicrobial applied in such an elution system should be active against the most commonly involved pathogens of chronic bone infections, namely, methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative staphylococci (CoNS) (5). Daptomycin, which is a novel lipopeptide antimicrobial with excellent in vitro activity against these isolates (4), may be a candidate for application in a system for local drug delivery.Stimulan (Biocomposites, Keele Science Park, Staffordshire, United Kingdom) is a synthetic biocompatible bone graft material made of calcium sulfate. It is completely reabsorbed and replaced with new bone. It is synthesized at 100% purity with no traces of potentially toxic impurities that have been associated with naturally occurring mineral sources of calcium sulfate. It has been recently shown by our group that moxifloxacin and fusidic acid may be eluted at high concentrations in vitro by using Stimulan as a carrier (11). The purpose of the present study was to develop an in vitro system for daptomycin elution by using Stimulan as a delivery system.Stimulan was mixed with daptomycin (Novartis, Basel, Switzerland) at a ratio 95:5 to a total weight of 3 g. This was put into sterile vials (160 by 100 mm) and left at room temperature for 15 to 30 min for solidification. Five similar vials were prepared. One milliliter of Mueller-Hinton broth (Trec Diagnostic Systems, West Sussex, United Kingdom) was added over the free surface of each mixture and replaced every 24 h. The vials were incubated at 37°C. On each consecutive day, the eluent was removed, transferred to a sterile plastic tube, and replaced with 1 ml of broth. That procedure was repeated until the optical degradation of the prepared mixture. Samples were stored at −70°C until analysis.Concentrations of daptomycin were estimated in duplicate by a modification of the method already described (3). Briefly, 300 μl of sample was mixed with 20 μl of 99% methanol and centrifuged for 10 min at 5,000 rpm and 4°C. Twenty microliters of the supernatant was injected into a high-pressure liquid chromatography system (1100 series; Agilent, Waldbronn, Germany) with the following elution characteristics: a Zorbax Eclipse XDB-C₈ (4.6 by 150 mm, 5 μm) separating column (Agilent Technologies) warmed at 37°C, a mobile phase of 32.6% acetonitrile and 67.4% 0.5% ammonium phosphate buffer at a flow rate of 1.5 ml/min, and UV detection at 214 nm. The retention time of daptomycin was 3.3 min, and it was estimated as micrograms per milliliter by a standard curve created with known concentrations of daptomycin. The lower detection limit was 6.25 μg/ml, and the interday coefficient of variation of the assay was 4.7%. Results were expressed as means ± standard errors. The area under curve (AUC) for each vial was determined by the linear trapezoidal rule.Elution of daptomycin lasted 28 days. Then the prepared mixture was destroyed. Eluted concentrations peaked on days 1 and 11, when the mean concentrations were 1,320.1 and 949.2 μg/ml, respectively. The lowest eluted concentration was detected on day 28, and the mean value was 233.9 μg/ml (Fig. ​(Fig.1).1). This gradual step-down rate of release over the 28 days was consistent for all five replicates. The mean ± standard deviation AUC of daptomycin elution over this 28-day period was 14,542.7 ± 1,925.9 μg · day/ml. Short peaks of daptomycin release were apparent on days 5 and 11. These may be related to the properties of Stimulan.Open in a separate windowFIG. 1.Elution of daptomycin by Stimulan.Daptomycin is a new lipopeptide that has been recently licensed for the management of skin and soft-tissue infections (13). It has excellent intrinsic activity against MRSA and methicillin-resistant CoNS but also vancomycin-resistant enterococci (10). The MICs for 90% of the strains of MRSA, methicillin-resistant CoNS, and vancomycin-resistant enterococcal isolates tested are reported to be 0.78, 0.44, and 0.5 μg/ml, respectively (1, 4). Although the eluted daptomycin concentrations obtained with the system described here are much greater than the above-mentioned MICs for 90% of the strains tested, results should be interpreted with caution, since the kinetics of release apply to an in vitro system and not to in vivo conditions. It should, however, be underscored that eluted levels are considerably greater than the concentrations that are required to eliminate the growth of small-colony variants of S. aureus that are often implicated in chronic bone infections (1).The estimated AUC of elution may be considered indirect evidence of the total amount of drug released (2). The AUC for daptomycin by the elution system presented here is much greater than the AUC required for the management of an experimental thigh infection with MRSA in mice (9).Calcium sulfate has been applied as a carrier for daptomycin in two previous studies. The drug was admixed with CaSO₄ in pellet form. The total time of drug elution was 28 days, but the eluted concentrations were 10- to 100-fold lower than those achieved here (12). Even at a low rate of elution, the drug amounts released inhibited the growth of 10⁴ CFU of two different locally instilled isolates, one of S. aureus and another of S. epidermidis (14).Although the effectiveness of daptomycin has not been evaluated in any prospective randomized clinical trial for the therapy of staphylococcal osteomyelitis, retrospective data favor its application for the management of such infections (8). These favorable clinical prospects, along with the successful in vitro elution of daptomycin from Stimulan reported in the present study, support the application of the biodegradable system described here in experimental models of osteomyelitis.     

Vanishing bone disease (Gorham-Stout syndrome): A review of a rare entity

Vanishing bone disease (Gorham-Stout syndrome) is a rare entity of unknown etiology, characterized by destruction of osseous matrix and proliferation of vascular structures, resulting in destruction and absorption of bone. Despite the extensive investigation of the pathogenetic mechanisms of the disease, its etiology hasn’t been clarified and several theories exist. The syndrome can affect one or multiple bones of the patient, including the skull, the upper and lower extremities, the spine and pelvis. The clinical presentation of a patient suffering from vanishing bone disease includes, pain, functional impairment and swelling of the affected region, although asymptomatic cases have been reported, as well as cases in which the diagnosis was made after a pathologic fracture. In this short review we summarize the theories regarding the etiology as well as the clinical presentation, the diagnostic approach and treatment options of this rare disease.     

Importance of establishing radiation protection culture in Radiology Department

The increased use of ionization radiation for diagnostic and therapeutic purposes, the rapid advances in computed tomography as well as the high radiation doses delivered by interventional procedures have raised serious safety and health concerns for both patients and medical staff and have necessitated the establishment of a radiation protection culture (RPC) in every Radiology Department. RPC is a newly introduced concept. The term culture describes the combination of attitudes, beliefs, practices and rules among the professionals, staff and patients regarding to radiation protection. Most of the time, the challenge is to improve rather than to build a RPC. The establishment of a RPC requires continuing education of the staff and professional, effective communication among stakeholders of all levels and implementation of quality assurance programs. The RPC creation is being driven from the highest level. Leadership, professionals and associate societies are recognized to play a vital role in the embedding and promotion of RPC in a Medical Unit. The establishment of a RPC enables the reduction of the radiation dose, enhances radiation risk awareness, minimizes unsafe practices, and improves the quality of a radiation protection program. The purpose of this review paper is to describe the role and highlight the importance of establishing a strong RPC in Radiology Departments with an emphasis on promoting RPC in the Interventional Radiology environment.     

Cutaneous Crohn''s disease mimicking Melkersson–Rosenthal syndrome: treatment with methotrexate

A woman with a 5-year history of unilateral orofacial granulomatosis required repeated evaluations (including sequential colonoscopies) to establish the diagnosis of cutaneous Crohn's disease, a condition that proved responsive to low doses of oral methotrexate administered weekly. To our knowledge this is the first report describing the use of methotrexate for treatment of orofacial granulomatosis caused by underlying Crohn's disease.     

Correlation of acetylcholinesterase activity in the brain and blood of wistar rats acutely infected with Trypanosoma congolense

ObjectiveTo investigate the neurotransmitter enzyme Acetylcholinesterase (AChE) activity in the brain and blood of rats infected with Trypanosoma congolense (T. congo).MethodsPresence and degree of parasitemia was determined daily for each rat by the rapid matching method. AChE activity was determined by preparing a reaction mixture of brain homogenate and whole blood with 5, 5-dithiobisnitrobenzioc acid (DTNB or Ellman's reagent) and Acetylthiocholine (ATC). The increase in absorbance was recorded at 436 nm over 10 min at 2 min intervals. Trypanosome species identification (before inoculation and on day 10 post infection) was done by Polymerase chain reaction using specific primers.ResultsThe AChE activity in the brain and blood decreased significantly as compared with the uninfected control. The AChE activity dropped to 0.32 from 2.20 μmol ACTC min^?1mg protein^?1 in the brain and 4.57 to 0.76 μmol ACTC min-1mg protein^?1 in the blood. The animals treated with Diminaveto at 3.5 mg/kg/d were observed to have recovered significantly from parasitemia and were able to regain AChE activity in the blood but not in the brain as compared to the control groups. We also observed, that progressive parasitemia resulted to alterations in PCV, Hb, RBC, WBC, neurophils, total protein, lymphocytes, monocytes and eosinophil in acute infections of T. congo. Polymerase chain reaction (PCR) of infected blood before inoculation and on day 10 post infection revealed 600 bp on agarose gel electrophoresis.ConclusionsThis finding suggest that decrease in AChE activity increases acetylcholine concentration in the synaptic cleft resulting to neurological failures in impulse transfer in T. congo infection rats.