Reliability of constant-load treadmill testing in patients with intermittent claudication

AIM

Constant-load treadmill testing is frequently used to estimate walking ability of patients with peripheral arterial disease and to assess changes in functional capacity following therapeutic interventions or through disease progression. The value of this test has frequently been disputed based on doubts concerning its reproducibility. The aim of this study was to investigate the reliability of treadmill testing at a speed of 3 km/h and a constant inclination of 12%.

METHODS

Sixty-eight patients with stable peripheral arterial disease who were familiar with treadmill testing underwent two sessions of walking exercise at 3 km/h and 12% inclination within three weeks. Initial claudication distance (ICD) and maximum walking distance (MWD) on the treadmill as well as reported walking distances on level ground at individual speed were recorded.

RESULTS

Correlation coefficients of 0.8 and within-subject variation coefficients of 15% for ICD and 13% for MWD demonstrated low variability of walking distances between visits. No learning effects were observed. Intra-class correlation coefficients of 0.78 for ICD and 0.83 for MWD proved good reproducibility of treadmill testing. Correlation of measured and reported walking distances was poor.

CONCLUSION

Constant-load treadmill testing at 3km/h and 12% inclination is a well reproducible method to investigate walking capacity of patients with stable intermittent claudication who are familiar with this test method. From treadmill walking distances, no conclusions should be drawn concerning the actual walking range of the patient.

Technical challenges and anatomic anomalies encountered during aortic surgery

Since the introduction of endovascular techniques for the treatment of aortic pathologies, clinical application of these lesser invasive procedures has increased exponentially during the last two decades and changed daily vascular practice completely. Starting in the infra-renal aorta, the indications for endovascular repair have gradually extended to the suprarenal aorta, aortic arch, descending and thoracoabdominal aorta. In addition, other pathologies than aneurysms have been treated by endovascular means, including dissection, traumatic injuries, penetrating aortic ulcer, intramural hematoma and aorto bronchial fistula. With increased application, short-term and longer-term technical failures have developed, in the majority of cases managed by repeat endovascular techniques. However, these complications cannot always be solved by endotechniques, requiring conversion to open surgery. At present there are additional reasons why open surgical repair remains a mainstay in the treatment of complex aortic diseases. Younger patients might choose for traditional surgery because of the unknown durability of complex endovascular reconstructions. Patients with connective tissue disease suffer from vulnerable aortic tissue in which endografts might behave different as compared to degenerative aneurysms. Therefore, the modern vascular surgeon should not only be trained in endovascular procedures but also master the wide spectrum of open surgical techniques. Besides anatomical knowledge and standard vascular handling, the surgeon must be familiar with unusual variations and unexpected situations.

Polymer-Derived Micro-Nano-Structured Si3N4/SiC-CompositeS

Micro-nano-structured Si3N4/SiC-composites were prepared by liquid phase sintering of either amorphous, polymer derived Si-C-N powder or SiC1+x coated OC-Si3N4 powder, followed by gas pressure sintering. The obtained microstructures were investigated by scanning and transmission electron microscopy (SEM, TEM). Nanosized SiC inclusions embedded in microcrystalline Si3N4 grains were analysed by elemental mapping with electron spectroscopie imaging (ESI).

XANES Studies at N and C K-Edge of Compounds in the Ternary System Si-C-N

We report on XANES-investigations at the nitrogen and carbon K-edge of Si-C-N containing solid phases prepared by the reaction of silicon tetrachloride with bis(trimethylsilyl)carbodiimide and annealing the reaction product at temperatures between room temperature (RT) and 1600°C. From the spectra it is possible to evidence the evolution of four phase regions and their different structural increments. We can relate the observed changes of atomic excitations to chemical and structural effects. By that means proposed structural models for the different phases are testified.

Organic electrospun nanofibers as vehicles toward intelligent pheromone dispensers: characterization by laboratory investigations

Organic nanofibers have a history of technical application in various independent fields, including medical technology, filtration technology, and applications of pharmaceuticals via inhalation into the lungs. Very recently, in a joint effort with polymer chemists, agricultural applications have been added to this list of priorities. The aim is finding novel approaches to insect control. Pheromones, dispensed in a quantifiable way, are being used here in disrupting the mating communication between male and female pest insects, e.g. the European grapevine moth Lobesia botrana (Lepidoptera: Tortricidae), where current dispenser technology does not fully meet the high expectations of growers and environmentalists with respect to longevity of constant release, self decomposition, mechanical distribution, renewability as well as sustainability of resources. The methodology of electrospinning is exhaustively covered by Greiner and Wendorff (2007), with technical details reported by Hellmann et al. (2009), Hein et al. (2011), and Hummel et al. (2010). Wind tunnel studies were run within a tunnel with adjustable laminar flow and 0.5 m/sec air velocity. Mass losses of the electrospun fiber bundles were determined with a sensitive analytical balance 2-3 times per week and recorded as time vs. mass change. CLSA experiments were performed with a self developed glass apparatus (Lindner, 2010) based on various suggestions of previous authors. Microgram quantities of volatile pheromone (E,Z)-7,9-Dodecadienylacetate were absorbed on a filter of rigorously purified charcoal and desorbed by repeated micro extraction with a suitable solvent mixture. Aliquots of the solution were subjected to temperature programmed capillary GLC. Retention times were used for identification, whereas the area covered by the pheromone peak originating from a FID detector signal was integrated and compared with a carefully calibrated standard peak. Since these signals were usually in the low nanogram range, several replications were averaged for statistical improvement. - Thermogravimetric analysis between ambient temperature and 500 degrees C provided a series of degradation curves where the diagram contained information on the evaporation of pheromone alone, polymer fiber alone and pheromone included in the fiber.- Microscopic investigations resulted in pictures of nanofibers from which the overall morphology and the fiber dimensions could be quantified. Organic nanofibers loaded with the grapevine moth pheromone have been well characterized by 5 different lab methods, followed by field bioassays reported elsewhere in these communications volumes (HUMMEL et al., 2011). This comprehensive analytical approach to fiber characterization is new and will be further refined. The federal agency JKI Berlin subjected the pheromone loaded organic fibers to various independent toxicological and ecotoxicological tests and found no adverse side effects.

Organic nanofibers containing insect pheromone disruptants: a novel technical approach to controlled release dispensers with potential for process mechanization

Beginning fifty years ago, the search for suitable dispensers containing insect pheromones grew with the availability of these synthetic biotechnical tools. Many economic entomologists and application engineers dearly wish they had the "smart, intelligent and ideal dispenser". More or less suitable approximations are available commercially, but none so far meets all demands. Under economic strictures, novel inexpensive systems would be advantageous with release characteristics tailored to the specific life histories of pest insects, the plants considered and the numerous requirements of growers alike. Simultaneously, their field distribution should be mechanizable and be accomplished by one (or very few) application runs. The dispensers should be biodegradable, biocompatible, sustainably applicable, and they should be based on renewable resources. This report presents first results of a novel organic, electrospun nanofiber dispenser with dimensions in the upper nanometer range. Its load of pheromone can be adjusted to be sufficient for 7 weeks of constant disruptive action in vineyards and can be directed against the European Grape Vine Moth Lobesia botrana (Lepidoptera: Tortricidae) which here serves as a readily available model. Mating disruption in L. botrana and the related Eupoecilia ambiguella is a well studied and developed engineering process. Equally, nanofiber production by electrospinning (for a comprehensive review see Greiner and Wendorff, 2007A, B) is well known and already has numerous applications in filtration technology, air conditioning, and medical wound dressing. Our goal was to bring together and successfully mate these (partly incompatible) technologies via technical tricks of a proprietary nature. Even though the lifetime and effectiveness of currently available nanofibers still must be doubled, the rather complicated system of their production and analysis is known well enough to identify the parameters that need future adjustment. Another challenge is the mechanical distribution of the fibers in the vineyards by suitable machinery. Also, in this respect, certain technical leads are available for future development.

Angiography catheter based bleeding complication at the access site related to neurofibromatosis I

Neurofibromatosis Type I (NF-I) is one of the most common inherited human diseases with an incidence of 1/3000. Besides the cardinal features, all organs or body structures as well as several arterial regions can occasionally be affected. We present an unusual case of an access-site hematoma following percutaneous transluminal coronary angioplasty in a patient suffering from NF-1. After exposure of the vessels, excessive bleeding from surrounding proliferations of supposedly neurofibromatous or ganglioneuromatous tissue was identified as the sole source of the hematoma. Patients with neurofibromatosis are at considerable risk of obtaining catheter interventions over the years. In this group, we strongly recommend an ultrasound examination of the arterial segment where the arterial access is planned. In case of suspicious findings an alternative approach should be preferred to avoid bleeding complications.

[Intraoperative neuromonitoring for prevention of neurological complications in aortic surgery]

AIM

Stroke and paraplegia are devastating complications of thoracic and thoracoabdominal aortic surgery. The aim of this study was to analyse the value of transcranial Doppler ultrasound (TCD), electroencephalogram (EEG) and motor-evoked potentials (MEP) in preventing neurological complications. Moreover, the principles, technology and surgical protocols are described.

PATIENTS AND METHODS

In 2009, 22 patients (4 females, 18 males) underwent thoracic or thoracoabdominal open aortic repair. We performed 2 arches with descending aortic replacement, 5 arches with TAAA repair, 2 type II, 9 type III, 3 type IV and one type V TAAA aortic repair. In 6 patients, the neuromonitoring included TCD, EEG and MEPs. In 15 patients only MEP monitoring was necessary. In one patient who was operated on in an emergency setting, neuromonitoring was not performed. The surgical approach was a left thoracotomy in 3 and a left thoracolaparotomy in 19 patients. The surgical protocol included cerebrospinal fluid drainage (n=22), moderate (n=19) or deep hypothermia (n=2), and extracorporeal circulation (n=21) with retrograde aortic perfusion and selective cerebral and/or viscerorenal perfusion.

RESULTS

In 21 patients, the neuromonitoring could be established successfully. Using TCD and EEG, a relevant cerebral ischaemia during supraaortic clamping was excluded. With a mean distal arterial pressure of 60 mmHg, the MEPs remained adequate in 15 patients (68.2%). Increasing of the blood pressure restored the MEPs in one patient. In 5 patients (22.7%), a reimplantation of segmental arteries (n=4) or of the left subclavian artery (n=1) re-established spinal cord perfusion, as indicated by restored MEPs. We had no absent MEPs at the end of the procedures. Delayed paraparesis developed in 2 patients with a haemodynamic instability during the postoperative course. Paraplegia was not observed.

CONCLUSION

TCD, EEG and MEPs are reliable techniques to unmask cerebral or spinal cord ischaemia during aortic surgery. Immediate operative strategies based on neuromonitoring information prevent neurological complications in aortic surgery.

Clinical benefit of hydroxyapatite-coated pins compared with stainless steel pins in external fixation at the wrist: a randomised prospective study

BACKGROUND

The purpose of this study was to determine the clinical benefit of hydroxyapatite (HA)-coated pins compared with standard stainless steel pins in external fixators applied for unstable fractures of the distal radius.

METHODS

A total of 40 patients (160 pins) with unstable wrist fractures were randomised for uniplanar fixator treatment with the use of identically designed, commercially available pins either composed of stainless steel (steel group) (n = 20) or coated by hydroxyapatite (HA group) (n = 20). Each pin site was clinically evaluated concerning erythema and grade of drainage as well as pain intensity (numeric rating scale (NRS) 0–10) and, additionally, radiological assessment was performed concerning pin-loosening/infection as well as fracture healing at T1 (Ø18 days), T2 (Ø44 days) and T3 (Ø65 days). In case of pintrack complication, the patient was followed continuously. The need for intensified pin-site care, oral or intravenous antibiotic medication, re-admission for additional surgery and premature fixator removal was documented. Bone mineral density (BMD) was determined by dual energy X-ray absorptiometry. At fixator removal (T2), the pin-extraction strength was measured by the use of an electronic torque wrench.

RESULTS

Two pin-track infections requiring daily pin-site care and oral antibiotics occurred in the HA group (2.6%) compared with four in the steel group (5.3%) (p = 0.601) and although a trend towards a superior performance of HA pins was detectable, the majority of clinical pin-site-parameters were comparable in both groups. At the end of the fixator therapy, the HA group showed a non-significant lower rate of loose pins (n(steel group) = 9; n(HA group) = 6; p = 0.864) and both hydroxyapatite-coated pins showed at the radius a significantly stronger pin-bone bonding measured by the torque wrench (p(proximal radius pin) = 0.007; p(distal radius pin) = 0.031). Except for elderly patients of the steel group (p = 0.018), all demographic-, health- and injury-related data including BMD were not correlated to any type of pin-site complication in both groups (p > 0.05). Since all fracture healed uneventfully without any type of additional surgery, the number of patients suffering clinically relevant pin-related complications showed no significant difference between both groups (p = 0.707).

CONCLUSIONS

The use of HA-coated pins compared with standard stainless-steel pins in external fixation for unstable wrist fractures yields only a trend towards a superior clinical outcome.

Marfan Syndrome: when to operate TAA(A)s?

Marfan Syndrome is a heritable disorder of connective tissue leading to aortic aneurysms and other cardiovascular complications associated with reduced life expectancy. Marfan patients with thoracic aortic aneurysms (TAAs) or with thoracoabdominal aortic aneurysms (TAAAs) should be treated by means of open surgery, requiring an extensive protocol, including extracorporeal circulation, neuromonitoring and adjunctive modalities to provide organ protection. Then, open surgical repair of TAA(A)s are associated with excellent results. However, in the last time a gradual change to endovascular treatment in Marfan patients is observable. Particularly in patients with an increased surgical risk due to redo sternotomy or thoracotomy, endovascular treatment might be an alternative due to its less invasive approach. Consequently, thoracic endovascular aortic repair comprises a therapeutic alternative in individual situations even in Marfan patients, when the landing zones are safe and appropriate. In cases of failed endovascular therapy, however, conversion to open surgery remains still an option with acceptable results, although the distal and proximal clamping positions change inappropriate with larger extensions due to the aortic stent.

[Retroperitoneal bronchogenic cyst treated by laparoscopic surgery]

The diagnosis of primary retroperitoneal cystic tumors is very infrequent in surgical pathology. We report the case of a 51-year-old woman presenting with an incidental left-sided retroperitoneal mass (32 x 24 mm in diameter) suspected of being an adrenal tumor. Intraoperatively the tumor was identified as a cystic lesion filled with mucous secretion and laparoscopically completely resected. The diagnosis was histopathologically confirmed as a bronchogenic cyst. In this article the laparoscopic removal of such a rare benign congenital aberration resulting from an abnormal budding of the tracheobronchial tree is presented.

Pancreatic graft survival despite partial vascular graft thrombosis due to splenocephalic anastomoses

Thrombotic complications following pancreas transplantation are still the most common cause of nonimmunologic graft loss. The aim of this study was to analyze pancreatic graft function after partial arterial graft thrombosis and the investigation of the pancreatic arterial anatomy with regard to intraparenchymal anastomoses. We retrospectively analyzed the data for 175 consecutive pancreas transplants performed between January 2002 and October 2007. Selective Y-graft angiography was performed in 10 and rubber-milk injection in 5 fresh pancreas specimens. Thrombosis of one leg of the Y-graft was diagnosed in 18 (10.3%) patients. Only one of these patients with thrombosis of the splenic artery required exogenous insulin. Sufficient graft perfusion was demonstrated in all of the remaining grafts. One graft was lost due to acute rejection. In all specimens angiography showed an excellent perfusion of the pancreaticoduodenal arcade, even after selective cannulation of the splenic artery. Arterial collaterals between the gastroduodenal, splenic artery and the superior mesenteric artery were demonstrated. Our results demonstrate that global perfusion of the pancreatic graft and sufficient graft function is sustained after the thrombotic occlusion of one branch of the Y-graft by a complex system of intraparenchymal anastomoses. These anatomical findings may have consequences for resection strategies in pancreas surgery.

Lack of obvious influence of PLLA nanofibers on the gene expression of BMP-2 and VEGF during growth and differentiation of human mesenchymal stem cells

Growth factors like bone morphogenetic protein 2 (BMP-2) and vascular endothelial growth factor (VEGF) play an important role in bone remodeling and fracture repair. Therefore, with respect to tissue engineering, an artificial graft should have no negative impact on the expression of these factors. In this context, the aim of this study was to analyze the impact of poly(L-lactic acid) (PLLA) nanofibers on VEGF and BMP-2 gene expression during the time course of human mesenchymal stem cell (hMSC) differentiation towards osteoblasts. PLLA matrices were seeded with hMSCs and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of VEGF and BMP-2. Furthermore, BMP-2–enwoven PLLA nanofibers were used in order to elucidate whether initial down-regulation of growth factor expression could be compensated. Although there was a great interpatient variability with respect to the expression of VEGF and BMP-2, PLLA nanofibers tend to result in a down-regulation in BMP-2 expression during the early phase of cultivation. This effect was diminished in the case of VEGF gene expression. The initial down-regulation was overcome when BMP-2 was directly incorporated into the PLLA nanofibers by electrospinning. Furthermore, the incorporation of BMP-2 into the PLLA nanofibers resulted in an increase in VEGF gene expression. Summarized, the results indicate that the PLLA nanofibers have little effect on growth factor production. An enhancement in gene expression of BMP-2 and VEGF can be achieved by an incorporation of BMP-2 into the PLLA nanofibers.

Genetically engineered attenuated measles virus specifically infects and kills primary multiple myeloma cells

The applicability of cytoreductive treatment of malignant diseases using recombinant viruses strongly depends on specific recognition of surface receptors to target exclusively neoplastic cells. A recently generated monoclonal antibody (mAb), Wue-1, specifically detects CD138(+) multiple myeloma (MM) cells. In this study, a haemagglutinin (H) protein that was receptor-blinded (i.e. did not bind to CD46 and CD150) was genetically re-engineered by fusing it to a single-chain antibody fragment (scFv) derived from the Wue-1 mAb open reading frame (scFv-Wue), resulting in the recombinant retargeted measles virus (MV)-Wue. MV-Wue efficiently targeted and fully replicated in primary MM cells, reaching titres similar to those seen with non-retargeted viruses. In agreement with its altered receptor specificity, infection of target cells was no longer dependent on CD150 or CD46, but was restricted to cells that had been labelled with Wue-1 mAb. Importantly, infection with MV-Wue rapidly induced apoptosis in CD138(+) malignant plasma cell targets. MV-Wue is the first fully retargeted MV using the restricted interaction between Wue-1 mAb and primary MM cells specifically to infect, replicate in and deplete malignant plasma cells.

High-energy phosphate metabolism in the exercising muscle of patients with peripheral arterial disease

Patients with peripheral arterial disease (PAD) suffer from impaired muscle function due to insufficient oxygen supply during exercise, mitochondrial damages, unfavourable muscle fibre type distribution and impaired exercise tolerance. These factors influence the symptoms as well as the quality of life in PAD patients and are closely connected to failures of high-energy phosphate metabolism. At onset of muscle exercise, the mitochondrial capacity cannot match the increased demand. The oxygen supply via blood flow must be increased. Meanwhile, anaerobic glycolysis and internal stores of oxygen like mixed venous blood and myoglobin as well as internal stores of high-energy phosphates like phosphocreatine (PCr) are adducted for the provision of additional adenosine-triphosphate (ATP), which is consumed by the ATPase at the myofibrils in order to fuel muscle contraction. Since the ATP production is insufficient, this phase (anaerobic phase) is characterized by a progressive decrease in PCr, which can be accurately measured by phosphorus 31 magnetic resonance spectroscopy (31p MRS). If the oxygen supply is improved, the mitochondrial capacity can match the increased metabolic demand. This phase is the aerobic phase, which is indicated by a steady-state of PCr hydrolysis. In PAD patients or experimental models of peripheral ischemia, the anaerobic phase is prolonged or does not pass into the aerobic phase resulting in exercise abortion. This review summarizes the results of 31p MRS studies investigating the high-energy phosphate metabolism during ischemic exercise in healthy humans and during ramp or incremental exercise in PAD patients.

Herpes simplex vegetans: atypical genital herpes infection with prominent plasma cell infiltration in B-cell chronic lymphocytic leukemia

SUMMARY

Herpes simplex vegetans is a rare disorder even in immunocompromised patients. It typically affects patients with HIV or myeloproliferative diseases.The atypical cutaneous lesions show papillomatous vegetations in varying locations. Histologically the lesions show pseudoepitheliomatous hyperplasia of squamous epithelium, plasma cell infiltration and are positive for HSV 1 and/or HSV 2. Herpes simplex vegetans often responds poorly to treatment in immunocom-promised patients.