[Evaluation of the efficiency of the zero-dose-C-arm navigation approach]

BACKGROUND

The efficiency and success of computer-assisted fluoroscopic navigation systems mainly depend on the quality of the process of image acquisition: obtaining the correct view of anatomic structures, relative orientation of multiplanar X-ray images and the necessary amount of radiation dose. These systems may be optimised by using a system called zero-dose c-arm navigation (ZDCAN). We investigate whether the available computer-assisted systems may be used to navigate the c-arm before image acquisition to obtain X-ray images with maximised accuracy and minimal radiation exposure.

METHODS

Based on position data of an optical tracking system combined with statistical deformable bone models, ZDCAN is able to generate a real-time preview of expected X-ray images of the lower extremities without using radiation. We performed a cadaver study on six full-body specimens comparing the zero-dose approach to conventional positioning of the c-arm in order to evaluate efficiency and accuracy. Eight users acquired two perpendicular X-ray images of the hip, the knee and the femoral diaphysis.

RESULTS

The number of X-ray images required to get a satisfying picture could be reduced to seven using the zero-dose approach; the conventional approach needed 11 images. The mean time did not differ significantly. Regarding the image quality, using ZDCAN quasi-orthogonality could be reached while the conventional approach showed a large variation of the relative orientation.

CONCLUSION

Using ZDCAN, the amount of radiation can be reduced by requiring less X-ray images as well as reaching better accuracy.

Association of rheumatoid arthritis with Mdm2 SNP309 and genetic evidence for an allele-specific interaction between MDM2 and p53 P72R variants: a case control study

OBJECTIVE

This study examines two common, functional, single nucleotide polymorphisms (SNP) in the genes coding the human homolog of murine-double-minute-2 (MDM2) and p53 in patients with rheumatoid arthritis (RA) based on the hypothesis that p53 may be an important negative regulator of the pro-inflammatory transcription factor nuclear factor kappa b (NFKappaB).

METHODS

Genomic DNA was obtained from 221 patients with RA who fulfilled at least 4 ACR criteria and from 521 healthy controls. Mdm2 SNP309 and p53 P72R were genotyped by polymerase chain reaction and restriction enzyme analysis.

RESULTS

In RA patients the frequencies of the mdm2 SNP309 G allele and both G-containing genotypes were significantly reduced (G allele: OR: 0.75, 95% CI: 0.59-0.95, p=0.016; genotype TG: OR: 0.71, 95% CI: 0.50-1.00; genotype GG: OR. 0.58, 95% CI: 0.34-0.99; both: p=0.049). Concerning p53 P72R, no differences in allele or genotype frequencies were detected. A combined analysis of both polymorphisms revealed a significant interaction between them (p=0.046). In individuals carrying >1 p53 72R allele, MDM2 had a protective effect, whereas in individuals homozygous for p53 72P, MDM2 had the opposite effect.

CONCLUSION

The function of MDM2 depends on the p53 P72R genotype, resulting in either an increased or reduced risk for RA. We suggest that in most cases MDM2 stabilizes the conformation of p53, whereas in p53 PP-positive subjects MDM2 supports the degradation of p53.

FDG uptake is a surrogate marker for defining the optimal biological dose of the mTOR inhibitor everolimus in vivo

This study aimed to test whether [¹⁸F]fluoro-D-glucose (FDG) uptake of tumours measured by positron emission tomography (PET) can be used as surrogate marker to define the optimal biological dose (OBD) of mTOR inhibitors in vivo. Everolimus at 0.05, 0.5, 5 and 15 mg kg⁻¹ per day was administered to gastric cancer xenograft-bearing mice for 23 days and FDG uptake of tumours was measured using PET from day 1 to day 8. To provide standard comparators for FDG uptake, tumour volume, S6 protein phosphorylation, Ki-67 staining and everolimus blood levels were evaluated. Everolimus blood levels increased in a dose-dependent manner but antitumour activity of everolimus reached a plateau at doses ⩾5 mg kg⁻¹ per day (tumour volume treated vs control (T/C): 51% for 5 mg kg⁻¹ per day and 57% for 15 mg kg⁻¹ per day). Correspondingly, doses ⩾5 mg kg⁻¹ per day led to a significant reduction in FDG uptake of tumours. Dose escalation above 5 mg kg⁻¹ per day did not reduce FDG uptake any further (FDG uptake T/C: 49% for 5 mg kg⁻¹ per day and 52% for 15 mg kg⁻¹ per day). Differences in S6 protein phosphorylation and Ki-67 index reflected tumour volume and changes in FDG uptake but did not reach statistical significance. In conclusion, FDG uptake might serve as a surrogate marker for dose finding studies for mTOR inhibitors in (pre)clinical trials.

Macroscopic brain architecture changes and white matter pathology in acromegaly: a clinicoradiological study

Although long-term exposure of the brain to increased GH/IGF-1 likely influences cerebral functions, no in vivo studies have been directed towards changes of the brain structure in acromegaly. Here, we used high resolution magnetic resonance images to compare volumes of gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) of forty-four patients with acromegaly to an age and gender matched, healthy control group (n = 44). In addition, white matter lesions (WMLs) were quantified and graded. Patients exhibited larger GM (+3.7% compared with controls, P = 0.018) and WM volumes (+5.1%, P = 0.035) at the expense of CSF. Differences of WML counts between patients and controls were subtle, however, showing more patients in the 21-40 lesions category (P = 0.044). In conclusion, this MRI study provides first evidence that acromegalic patients exhibit disturbances of the macroscopic brain tissue architecture. Furthermore, acromegalic patients may have an increased risk of neurovascular pathology, likely due to secondary metabolic and vascular comorbidities.

Analysis of cell surface proteome changes via label-free, quantitative mass spectrometry

We present a mass spectrometry-based strategy for the specific detection and quantification of cell surface proteome changes. The method is based on the label-free quantification of peptide patterns acquired by high mass accuracy mass spectrometry using new software tools and the cell surface capturing technology that selectively enriches glycopeptides exposed to the cell exterior. The method was applied to monitor dynamic protein changes in the cell surface glycoproteome of Drosophila melanogaster cells. The results led to the construction of a cell surface glycoprotein atlas consisting of 202 cell surface glycoproteins of D. melanogaster Kc167 cells and indicated relative quantitative changes of cell surface glycoproteins in four different cellular states. Furthermore we specifically investigated cell surface proteome changes upon prolonged insulin stimulation. The data revealed insulin-dependent cell surface glycoprotein dynamics, including insulin receptor internalization, and linked these changes to intracellular signaling networks.

Angiotensin inhibition stimulates PPARgamma and the release of visfatin

BACKGROUND

Angiotensin converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARB) exhibit beneficial antidiabetic effects in patients with type 2 diabetes independent of their blood pressure-lowering effects. Some antidiabetic properties of ARB and ACE-I might by exerted by activation of peroxisome proliferator-activated receptor gamma (PPARgamma). However, it is not clear whether this action is drug specific.

MATERIALS AND METHODS

The binding affinity of telmisartan, valsartan, lisinopril, rosiglitazone and angiotensin II to PPARgamma was assessed in a cell-free assay system. PPARgamma signalling was studied in isolated skeletal muscle cells using Western blot analysis of phosphorylated protein kinase B (pAKT) and phosphorylated insulin like growth factor-1 receptor (pILGF-1R). Further, the ability of the drugs under study to stimulate the release of the adipocytokine visfatin was investigated in isolated human adipocytes, skeletal muscle cells, and umbilical vein endothelial cells (HUVEC).

RESULTS

The binding affinity to PPARgamma was highest for telmisartan with a half-maximal effective concentration of 463 nM, followed by lisinopril (2.9 microM) and valsartan (6.2 microM). In skeletal muscle cells phosphorylation of ILGF-1R was 2-fold increased after incubation with telmisartan or valsartan and 1.7-fold with lisinopril. pAKT expression was enhanced after incubation with telmisartan, valsartan and with lisinopril. The release of visfatin from adipocytes was 1.6-fold increased after treatment with lisinopril and about 2.0-fold increased with telmisartan and valsartan. Similar results were obtained in skeletal muscle cells and HUVEC.

CONCLUSIONS

Our data confirm agonism of telmisartan, valsartan and lisinopril on PPARgamma. Pharmacokinetic differences may explain different potencies of PPARgamma stimulation by drugs acting on the renin-angiotensin system in clinical settings.

Porous biodegradable microtubes-based scaffolds for tissue engineering, part I: production and preliminary in vitro evaluation

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PURPOSE

</b></i>we aimed at investigating spinning as a potential technology to produce porous microtubes for constructing scaffolds. Spinning is indeed a well known technique for producing polymeric fibres, also used in the biomedical field, but its applications for tissue engineering purposes has never been deeply investigated. <i><b>

METHOD

</b></i> the behaviour of a multi-phase poly-lactide-caprolactone copolymer based solution was here studied for the production under spinning condition of porous microtubes for patterning planar and three dimensional bioactive systems to be used for tissue regeneration. Obtained non-woven fabrics were tested investigating cells response with fibroblast, osteoblasts and chondrocytes. <i><b>

RESULTS

</b></i>once achieved optimal process parameters, microtubes were produced with a controlled and well diffused porosity which were then used to build two and three dimensional scaffolds. Cytocompatibility tests performed on these scaffolds showed good results on all tested cell models, both qualitatively (SEM imaging) and quantitatively. Particularly, cell proliferation assays by Alamar Blue staining indicated increasing trends with time and comparable values with controls. <i><b>

CONCLUSIONS

</b></i>results hereby described represent a proof of concept of the process developed and its applicability for obtaining microtubes with controlled porosity. Moreover, two and three dimensional scaffolds built from such fibres showed to be very promising substrates for cell adhesion and growth. Finally, the process developed can be taken into GMP qualification and thus scaffolds can be upgraded to medical devices and used for regenerative medicine into human applications.

[Valgus osteotomy of the subcapital humerus: a reconstructive procedure after post-traumatic malalignement]

AIM

Post-traumatic humerus varus can develop after an insufficient reduction technique. Reduced abduction, anteversion or rotation is seen, often associated with painful impingement. The radiographic sign is a diminished shaft-head angle less than 140 degrees with a consecutive elevation of the greater tubercule above the head rim and a subacromial narrowing. We analysed the data of the Constant score pre- and postcorrectionem.

METHODS

Between 1992 and 1999 we treated 8 patients with post-traumatic humerus varus. The follow-up time lasted for 3 years after the correction procedure. By means of the Constant score we evaluated the pre- and postoperative results. In addition, we measured the radiological changes of the humerus head-shaft angles. Furthermore, we controlled the arm length before and after the corrective osteotomy.

RESULTS

The age at the time of correction averaged 43 years (23 years to 65 years). In 6 patients a closing wedge was performed on the right shoulder and two times on the left side. 2 patients had an additional retrotorsional malalignment, which was corrected by means of derotation. In 5 cases cancellous bone was attached to the osteotomy plane. The average delay between the first and the second operation was 8 months (range from 4 weeks to 12 months). The Constant score improved from 39.5 to 75.5 points. The radiological head-shaft angle increased from 84 degrees to 130 degrees . The arm shortening decreased from 2 cm to less than 1 cm. Osseous consolidation of the osteotomy was established after 8.5 weeks. In one case we saw a pseudarthrotic osteotomy plane and treated it by plate extension and cancellous bone grafting.

CONCLUSION

The valgus osteotomy of the humeral neck is an extra-articular reconstructive procedure to correct a malpositioning between humeral head and shaft. It improves both radiological and clinical results. It is a demanding procedure regarding indication and operative technique.

An integrated, directed mass spectrometric approach for in-depth characterization of complex peptide mixtures

LC-MS/MS has emerged as the method of choice for the identification and quantification of protein sample mixtures. For very complex samples such as complete proteomes, the most commonly used LC-MS/MS method, data-dependent acquisition (DDA) precursor selection, is of limited utility. The limited scan speed of current mass spectrometers along with the highly redundant selection of the most intense precursor ions generates a bias in the pool of identified proteins toward those of higher abundance. A directed LC-MS/MS approach that alleviates the limitations of DDA precursor ion selection by decoupling peak detection and sequencing of selected precursor ions is presented. In the first stage of the strategy, all detectable peptide ion signals are extracted from high resolution LC-MS feature maps or aligned sets of feature maps. The selected features or a subset thereof are subsequently sequenced in sequential, non-redundant directed LC-MS/MS experiments, and the MS/MS data are mapped back to the original LC-MS feature map in a fully automated manner. The strategy, implemented on an LTQ-FT MS platform, allowed the specific sequencing of 2,000 features per analysis and enabled the identification of more than 1,600 phosphorylation sites using a single reversed phase separation dimension without the need for time-consuming prefractionation steps. Compared with conventional DDA LC-MS/MS experiments, a substantially higher number of peptides could be identified from a sample, and this increase was more pronounced for low intensity precursor ions.

First-aid sensor system: new methods for single-point detection and analysis of vital parameters such as pulse and respiration

The paper describes a first aid medical sensor system that is able to detect pulse and respiration. According to an opinion poll 79% of unexperienced first aiders were looking forward to use a system that supports them in first aid situations. Such a device has to be reliable and available in everyday use (e.g. as a keychain or in a first-aid kit). Therefore we investigated a single point sensor that is able to detect both respiration and blood flow at the same point of the body, for instance on the neck. Compared to ECG-derived methods absent pulse due to pulseless electrical activity (PEA) will be recognized as such. Tests have shown that the sensor can also be used to detect deglutition and other body motion sequences.

Insights into linear and rank correlation for material identification in laser-induced breakdown spectroscopy and other spectral techniques

The purpose of this work was to critically assess the potential and limitations of linear and rank correlation methods, not only relevant to laser-induced breakdown spectroscopy (LIBS), but to other spectroscopic techniques as well. Through computer simulations, it was demonstrated that a linear correlation is a more suitable technique for material identification than a rank correlation due to its better stability toward noise and better ability to detect small systematic variations in line intensities. The effect of noise on the results of correlation analysis has been studied. It was found that random noise causes correlation coefficients to be distributed normally, whereas flicker noise (random fluctuations in line intensities) results in a gamma distribution of correlation coefficients. Hence, the distribution of correlation coefficients can be used for detection of the type of noise that dominates correlated spectra. A potential of linear correlation analysis for plasma diagnostics has been demonstrated. It is based on a strong dependence of the linear correlation coefficient upon the line shapes of correlated spectral lines and, consequently, upon plasma parameters (plasma temperature, number densities).

[Laparoscopy in the management of endometrial cancer]

Recent advance in laparoscopy have changed the surgical approach of endometrial cancer patients. The Swissendos Center, Fribourg, in collaboration with AGO (Groupe de travail pour la gynécologie oncologique) and AGE (groupe de travail pour la gynécologie endoscopique) have established a consensus based on the available evidence for the use of laparoscopy in the management of patients with endometrial cancer The main objective was to define Swiss clinical practice guidelines appropriate to the country and consistent with the needs of the physicians.