Can diffusion kurtosis imaging improve the sensitivity and specificity of detecting microstructural alterations in brain tissue chronically after experimental stroke? Comparisons with diffusion tensor imaging and histology

Imaging techniques that provide detailed insights into structural tissue changes after stroke can vitalize development of treatment strategies and diagnosis of disease. Diffusion-weighted MRI has been playing an important role in this regard. Diffusion kurtosis imaging (DKI), a recent addition to this repertoire, has opened up further possibilities in extending our knowledge about structural tissue changes related to injury as well as plasticity. In this study we sought to discern the microstructural alterations characterized by changes in diffusion tensor imaging (DTI) and DKI parameters at a chronic time point after experimental stroke. Of particular interest was the question of whether DKI parameters provide additional information in comparison to DTI parameters in understanding structural tissue changes, and if so, what their histological origins could be. Region-of-interest analysis and a data-driven approach to identify tissue abnormality were adopted to compare DTI- and DKI-based parameters in post mortem rat brain tissue, which were compared against immunohistochemistry of various cellular characteristics. The unilateral infarcted area encompassed the ventrolateral cortex and the lateral striatum. Results from region-of-interest analysis in the lesion borderzone and contralateral tissue revealed significant differences in DTI and DKI parameters between ipsi- and contralateral sensorimotor cortex, corpus callosum, internal capsule and striatum. This was reflected by a significant reduction in ipsilateral mean diffusivity (MD) and fractional anisotropy (FA) values, accompanied by significant increases in kurtosis parameters in these regions. Data-driven analysis to identify tissue abnormality revealed that the use of kurtosis-based parameters improved the detection of tissue changes in comparison with FA and MD, both in terms of dynamic range and in being able to detect changes to which DTI parameters were insensitive. This was observed in gray as well as white matter. Comparison against immunohistochemical stainings divulged no straightforward correlation between diffusion-based parameters and individual neuronal, glial or inflammatory tissue features. Our study demonstrates that DKI allows sensitive detection of structural tissue changes that reflect post-stroke tissue remodeling. However, our data also highlights the generic difficulty in unambiguously asserting specific causal relationships between tissue status and MR diffusion parameters.

Investigating the antiproliferative activity of quinoline-5,8-diones and styrylquinolinecarboxylic acids on tumor cell lines

The structure-activity relationships of new quinoline based compounds were investigated. Quinoline-5,8-dione and styrylquinoline scaffolds were used for the design of potentially active compounds. The novel analogues had comparable antiproliferative activity to cisplatin when evaluated in a bioassay against the P388 leukemia cell line. However, these compounds appeared far less efficient against SK-N-MC neuroepithelioma cells. Analogues without the 5,8-dione structure but containing the 8-carboxylic acid group were also found to induce antiproliferative activity. Hydrophobicity as measured by HPLC did not correlate with antiproliferative activity.

Surgery for body packing in the Caribbean: a retrospective study of 70 patients

BACKGROUND

Body packing is a way to deliver packages of drugs hidden in body cavities, across international borders. This may cause mechanical bowel obstruction and intoxication leading to emergency surgery. The objective of this retrospective study is to evaluate pre-, per- and postoperative characteristics of body packing and its complications and prognosis after surgery.

METHODS

Medical information was obtained from 70 patients diagnosed with Body Packer syndrome who underwent surgery for body packing in the period of July 2001-July 2005 at the St. Elisabeth hospital, Curaçao, the Netherlands Antilles.

RESULTS

Wound infection occurred in 32.9% and fascia dehiscence in 2.9%. Most procedures were enterotomies. One patient had a re-laparotomy for Hartmann's procedure because of an anastomotic leak and three other patients had a partial small bowel resection. The creation of a stoma was only needed in one patient. One patient died of postoperative DIC. In six patients packages were left behind, not requiring re-operation.

CONCLUSIONS

Bowel obstruction and symptoms of intoxication are clear indications for surgery in body packing patients. In our study there was a low mortality and stoma placement rate, we did find a remarkable high amount of wound infection but no evidence for a higher incidence of fascia dehiscence in comparison with elective gastrointestinal surgery. In surgery for bodypacking a mandatory postoperative x-ray is indicated. A prospective trial is needed to assess more information about possible predictive factors of postoperative complications and mortality after surgery for body packing.

The calcineurin inhibitor tacrolimus allows the induction of functional CD4CD25 regulatory T cells by rabbit anti-thymocyte globulins

Rabbit anti-thymocyte globulins (rATG) induce CD4(+)CD25(+)forkhead box P3 (FoxP3(+)) regulatory T cells that control alloreactivity. In the present study, we investigated whether rATG convert T cells into functional CD4(+)CD25(+)FoxP3(+)CD127(-/low) regulatory T cells in the presence of drugs that may hamper their induction and function, i.e. calcineurin inhibitors. CD25(neg) T cells were stimulated with rATG or control rabbit immunoglobulin G (rIgG) in the absence and presence of tacrolimus for 24 h. Flow cytometry was performed for CD4, CD25, FoxP3 and CD127 and the function of CD25(+) T cells was examined in suppression assays. MRNA expression profiles were composed to study the underlying mechanisms. After stimulation, the percentage CD4(+)CD25(+)FoxP3(+)CD127(-/low) increased (from 2% to 30%, mean, P < 0.01) and was higher in the rATG samples than in control rIgG samples (2%, P < 0.01). Interestingly, FoxP3(+)T cells were also induced when tacrolimus was present in the rATG cultures. Blockade of the interleukin (IL)-2 pathway did not affect the frequency of rATG-induced FoxP3(+) T cells. The rATG tacrolimus-induced CD25(+) T cells inhibited proliferative responses of alloantigen-stimulated effector T cells as vigorously as rATG-induced and natural CD4(+)CD25(+)FoxP3(+)CD127(-/low) T cells (67% +/- 18% versus 69% +/- 16% versus 45% +/- 20%, mean +/- standard error of the mean, respectively). At the mRNA-expression level, rATG-induced CD25(+) T cells abundantly expressed IL-10, IL-27, interferon (IFN)-gamma, perforin and granzyme B in contrast to natural CD25(+) T cells (all P = 0.03), while FoxP3 was expressed at a lower level (P = 0.03). These mRNA data were confirmed in regulatory T cells from kidney transplant patients. Our findings demonstrate that tacrolimus does not negatively affect the induction, phenotype and function of CD4(+)CD25(+) T cells, suggesting that rATG may induce regulatory T cells in patients who receive tacrolimus maintenance therapy.

A new technique of microvascular suturing: the chopstick rest technique

With the conventional techniques of tying knots during microvascular anastomosis or neural suturing, time may be lost due to various reasons. The loose end of the suture often falls down into the operative field and gets stuck to the surrounding tissues. In the process of retrieving the suture, the surrounding tissues can be picked up together with the suture. When the posterior wall technique [Br J Plast Surg 34 (1981) 47, Plast Reconstr Surg 69 (1982) 139, Microsurgery 8 (1987) 22, J Reconstr Microsurg 15 (1999) 321] is used, the loose end of the suture may be stuck to the backside of the vessel and may be hard to grab. In order to avoid those problems, a new way of tying a microsuture was developed. By avoiding contact of the loose end of the suture to the surrounding tissue at any point during tying, the microvascular anastomosis can be performed quicker and more efficiently.

PCR-mediated genotyping of Candida albicans strains from bone marrow transplant patients

DNA amplification using polymerase chain reaction (PCR) primers aiming at eukaryotic or prokaryotic repetitive DNA motifs enables discrimination between individual Candida albicans isolates. This PCR-mediated DNA fingerprinting procedure was used to monitor yeast colonisation in immune-compromised leukaemia patients (n = 11) who were undergoing bone marrow transplantation (BMT). The leukaemia patients remained colonised by the same strain throughout a 5 month study period, irrespective of intermediate treatment with fungostatics or application of BMT-related therapies. All 11 strains could be identified separately by PCR fingerprinting. This implies that spreading of C. albicans from patient to patient does not seem to occur in this study group, despite the fact that medical employees frequently travel between wards which are in close proximity to other departments harbouring neutropenic patients. Several of the patients (n = 35) were also monitored for C. albicans colonisation and strain typing corroborated the lack of extensive cross-contamination during the study period. The application of PCR-mediated genotyping of fungi in epidemiological analyses and evaluation of hospital hygiene is discussed.

Percutaneous sclerotherapy for arteriovenous malformations of the face in the outpatient clinic

Sclerotherapy for arteriovenous malformations has to be performed under general anaesthesia because of the pain during injection and the need of careful monitoring. Two cases with arteriovenous malformations of the face regions are presented in whom percutaneous sclerotherapy was performed under local anaesthesia in the outpatient clinic. The sessions were uneventful and there was a visible decrease in the overall size and an improvement in skin colour of the lesion could be seen. Sclerotherapy can be used in the outpatient clinic to treat arteriovenous malformations that have a slow flow or a venous outflow that can be compressed to artificially slow the flow during injection.