Trans-radial cerebral angiography for stereotactic radiosurgery treatment of arteriovenous malformations.

OBJECTIVES: The popularity of trans-radial access (TRA) for cerebral angiography is growing. Potential benefits of TRA over traditional trans-femoral access (TFA) are multitude. This study aimed to evaluate discharge outcomes and patient opinion of TRA compared to TFA in patients undergoing cerebral angiography prior to stereotactic radiosurgery (SRS) treatment for cerebral arteriovenous malformations. METHODS: Consecutive patients treated at the National Centre for Stereotactic Radiosurgery (Sheffield, United Kingdom) over a 22-month period were included. All patients underwent cerebral angiography with either TRA or TFA as part of treatment planning prior to SRS. TRA patients who had previously undergone TFA in other centres were surveyed for their experience of cerebral angiography using a questionnaire. SRS staff at our centre was approached for their opinion. RESULTS: 492 patients were included (median age = 43 years, 57.5% male, median lesions treated = 1). More patients underwent angiography with TFA (75.2%) than TRA (24.8%). No difference was found in accumulated dose for angiography between the groups (p>0.05). There was 17.6% reduction in overnight stay between TRA and TRF, the proportion of patients requiring overnight admission was higher for the TFA (35.2%) than TRA (17.6%, p<0.05). 101 patients were surveyed, with a response rate of 47%. Most respondents (79%) indicated preference for TRA over TFA. CONCLUSIONS: Use of TRA in pre-SRS cerebral angiography is feasible and improves both patient and staff experience. The adoption of TRA could have important implications for department resources and costs by reducing the proportion of overnight admissions.

Impedimetric sensing of cells on polypyrrole-based conducting polymers.

Polypyrrole (PPy) is a conducting polymer that may be electrochemically generated with the incorporation of any anionic species, including net-negatively charged biological molecules such as proteins and polysaccharides. In this article, dermatan and chloride-loaded PPy films were prepared on gold sputter-coated coverslips and various skin derived cells were studied on them by electrochemical impedance spectroscopy. Impedance spectra in the frequency range 1-100 kHz were either determined at specific times or impedance was monitored continuously at specific frequencies. An equivalent impedance circuit was fitted to the recorded impedance spectra to obtain parameters whose contributions could be mapped to intracellular and intercellular current pathways, and the membrane properties of cells. Results show cell-induced impedance changes were detected over PPy modified electrodes and were dependent on cell density and type, monitoring frequency, material composition, and treatment. Lower cell densities were detected on PPy when compared with bare gold. Keratinocyte confluence, as determined by impedimetric analysis, was reached more rapidly on PPy than on gold. This was consistent with previous, more cumbersome, biochemical assays. Electrical equivalent circuit analysis provided evidence that the technique may be extended to discriminate cell type because of the intracellular and intercellular resistance, and cell membrane capacitance being related to cell morphology.

A novel cell array technique for high-throughput, cell-based analysis.

Microarray technology has burgeoned over the past few years from nucleic acid-based arrays to tissue microarrays (TMAs). This study aimed to develop a technique to incorporate cell lines into an array and to demonstrate the usefulness of this technique by performing immunohistochemistry for beta-catenin. Cell suspensions were prepared from 23 tumor cell lines. These were fixed in formalin, suspended in agar, and embedded in paraffin to produce a cell block. A "tissue microarrayer" was used to remove triplicate, 0.6 mm-cores from each cell block and to transfer these into a recipient paraffin block at precise coordinates. Immunohistochemistry was used to identify cell lines positive for beta-catenin. Cultured cells were successfully incorporated into the microarray, with preservation of cell architecture and even distribution of cells within each core. A total of 18 of 69 cores (26%) were lost in processing. A total of 16 of 23 cell lines were identified as positive for membrane and cytoplasmic beta-catenin, and 6 of 23 were negative. Only one cell line was unscorable because of complete core loss. We have developed a "cell microarray" technique for analyzing antigen expression by immunohistochemistry in multiple cell lines in a single experiment. This novel application of microarrays permits high-throughput, cost-efficient analysis, with the potential to rapidly identify markers with potential diagnostic and therapeutic implications in human disease.

Pyoderma gangrenosum--an unusual differential diagnosis for acute infection.

Pyoderma gangrenosum rarely occurs in the breast and has only previously been reported in the literature in response to trauma. We describe a case occurring spontaneously in the breast that was initially mistaken for an infection.

Tissue microarrays--big potential from small samples (review).

For well over a century, pathologists have used formalin-fixed paraffin-embedded tissues for microscopic examination and subsequent diagnosis of human disease. However, this type of approach is usually limited to the analysis and/or detection of one or two specific features on a single slide from an individual section. This area of histological study has been revolutionised by the development of tissue microarrays (TMAs). This review describes the development and use of TMAs and discusses their possible applications to clinical oncological practice.

Endovascular repair of an inflammatory abdominal aortic aneurysm complicated by aortoduodenal fistulation with an unusual presentation.

Aortoenteric fistulation (AEF) is a well-documented late complication of open abdominal aortic aneurysm (AAA) repair, occurring in between 0.4% and 4% of cases. In the absence of an anastomosis, AEF is likely to be rare after endovascular aneurysm repair (EVAR) and has only recently been described in the literature as a result of mechanical stent failure or migration. We present the case of a 61-year-old man who underwent EVAR for an AAA with a "nonspecific" periaortic inflammatory mass. Six months postoperatively, an AEF developed, presenting with metastatic sepsis followed by septic infective thromboembolization to his right leg, and amputation was necessary. His stent was well positioned and mechanically intact. We emphasize the need for vigilance about the risk of AEF when adopting an endovascular approach to repair the AAA with a nonspecific periaortic inflammatory mass and highlight the need for awareness about the unusual septic manifestations of AEF.

Mk3.5: a modular, multi-frequency successor to the Mk3a EIS/EIT system.

This paper describes the Sheffield Mk3.5 EIT/EIS system which measures both the real and imaginary part of impedance at 30 frequencies between 2 kHz and 1.6 MHz. The system uses eight electrodes with an adjacent drive/receive electrode data acquisition protocol. The system is modular, containing eight identical data acquisition boards, which contain DSPs to generate the drive frequencies and to perform the FFT used for demodulation. The current drive is in three sequentially applied packets, where each packet contains ten summed sine waves. The data acquisition system is interfaced to a host PC through an optically isolated high speed serial link (RS485) running at 2 Mbaud (2 Mbits s(-1)). Measurements on a saline filled tank show that the average signal to noise performance of the system is 40 dB measured across all frequencies and that this figure is independent of frequency of measurement. These results suggest that the current system is 10 dB better in absolute terms than the previous Sheffield (Mk3a) system.

Cole equation modelling to measurements made using an impulse driven transfer impedance system.

Electrical impedance measurements are used to obtain information about a subject, tissue sample or tissue model under test. There are several ways of obtaining these impedance data and thereafter analysing the data to obtain relevant parameters. This paper shows how a completely isolated drive and receive system using current pulses, as opposed to sine waves, achieves good fitted results with resistor-capacitor Cole phantoms.