Clostridium perfringens: a rare cause of spondylodiscitis case report and review of the literature.

Presented is a case of a 64-year old male with a unique and yet unreported case of a spondylodiscitis caused by Clostridium perfringens. Becoming symptomatic with massive neurological deficits. Computed tomography (CT) revealed typical signs of spondylodiscitis involving the vertebral body L5 with extensive vacuum phenomenon.

The accuracy and safety of fluoroscopically guided percutaneous pedicle screws in the lumbosacral junction and the lumbar spine: a review of 880 screws.

We undertook a retrospective study investigating the accuracy and safety of percutaneous pedicle screws placed under fluoroscopic guidance in the lumbosacral junction and lumbar spine. The CT scans of patients were chosen from two centres: European patients from University Medical Center Hamburg-Eppendorf, Germany, and Asian patients from the University of Malaya, Malaysia. Screw perforations were classified into grades 0, 1, 2 and 3. A total of 880 percutaneous pedicle screws from 203 patients were analysed: 614 screws from 144 European patients and 266 screws from 59 Asian patients. The mean age of the patients was 58.8 years (16 to 91) and there were 103 men and 100 women. The total rate of perforation was 9.9% (87 screws) with 7.4% grade 1, 2.0% grade 2 and 0.5% grade 3 perforations. The rate of perforation in Europeans was 10.4% and in Asians was 8.6%, with no significant difference between the two (p = 0.42). The rate of perforation was the highest in S1 (19.4%) followed by L5 (14.9%). The accuracy and safety of percutaneous pedicle screw placement are comparable to those cited in the literature for the open method of pedicle screw placement. Greater caution must be taken during the insertion of L5 and S1 percutaneous pedicle screws owing to their more angulated pedicles, the anatomical variations in their vertebral bodies and the morphology of the spinal canal at this location.

[Intraoperative electrophysiological monitoring with evoked potentials]. / Intraoperatives elektrophysiologisches Monitoring mit evozierten Potenzialen.

During the last 30 years intraoperative electrophysiological monitoring (IOEM) has gained increasing importance in monitoring the function of neuronal structures and the intraoperative detection of impending new neurological deficits. The use of IOEM could reduce the incidence of postoperative neurological deficits after various surgical procedures. Motor evoked potentials (MEP) seem to be superior to other methods for many indications regarding monitoring of the central nervous system. During the application of IOEM general anesthesia should be provided by total intravenous anesthesia with propofol with an emphasis on a continuous high opioid dosage. When intraoperative MEP or electromyography guidance is planned, muscle relaxation must be either completely omitted or maintained in a titrated dose range in a steady state. The IOEM can be performed by surgeons, neurologists and neurophysiologists or increasingly more by anesthesiologists. However, to guarantee a safe application and interpretation, sufficient knowledge of the effects of the surgical procedure and pharmacological and physiological influences on the neurophysiological findings are indispensable.

Time-course-dependent microvascular alterations in a model of myeloid leukemia in vivo.

Functional and morphological properties of tumor microcirculation play a pivotal role in tumor progression, metastasis and inefficiency of tumor therapies. Despite enormous insights into tumor angiogenesis in solid tumors, little is known about the time-course-dependent properties of tumor vascularization in hematologic malignancies. The aim of this study was to establish a model of myeloid leukemia, which allows long-term monitoring of tumor progression and associated microcirculation. Red fluorescent protein-transduced human leukemic cell lines (M-07e) were implanted into cranial windows of severe combined immunodeficient mice. Intravital microscopy was performed over 55 days to measure functional (microvascular permeability, tissue perfusion rate and leukocyte-endothelium interactions) and morphological vascular parameters (vessel density, distribution and diameter). Tumor progression was associated with elevated microvascular permeability and an initial angiogenic wave followed by decreased vessel density combined with reduced tissue perfusion due to loss in small vessels and development of heterogenous tumor vascularization. Following altered geometric resistance of microcirculation, leukocyte-endothelium interactions were more frequent without increased leukocyte extravasation. It was concluded that time-dependent alterations of leukemic tumor vascularization exhibit strong similarities to those found in solid tumors. The potential contribution to the development of barriers to drug delivery in leukemic tumors is discussed.

TNF-alpha alters visfatin and adiponectin levels in human fat.

Adiponectin and visfatin are newly discovered adipokines that are strongly expressed in human visceral adipose tissue. To identify new regulatory mechanisms in fat, the effect of TNF-alpha (TNF) on adiponectin, on its two receptors, and on visfatin was investigated by incubating human visceral adipose tissue from patients without diabetes mellitus with TNF for 24, 48 and 72 hours. The mRNA expression of visfatin, adiponectin, and its two receptors, as well as the protein expression of adiponectin were determined. A decrease of adiponectin mRNA expression of 97% after incubation with TNF (5.75 nmol/l) for 24 hours, a decrease of 91% after 48 hours, and a decrease of 96% after 72 hours were measured. The reduction of protein expression was measured to be 42% after 24 hours, 28% after 48 hours, and 39% after 72 hours of incubation with TNF (5.75 nmol/l). The mRNA level of adiponectin receptor 1 (AdipoR1) was elevated about 72% after 48 hours of incubation and 67% after 72 hours of incubation, whereas the mRNA expression of adiponectin receptor 2 (AdipoR2) was not altered significantly. The visfatin mRNA level was found to be highly increased by 255% after 24 hours and 335% after 48 hours and 341% after 72 hours of incubation with TNF (5.75 nmol/l). Our results support the concept of visceral adipose tissue as an endocrine organ. We demonstrate that TNF has regulatory functions on adiponectin, AdipoR1 and on visfatin in human visceral adipose tissue. TNF levels are elevated in states of obesity and insulin resistance. Due to this fact TNF could be the reason that there is a decrease in the level of adiponectin, whereas there is an increase in the level of visfatin in states of obesity and insulin resistance.

[Urgent indications for spinal surgery in patients with rheumatoid inflammation]. / Dringliche Operationsindi- kationen an der Wirbelsäule bei entzündlichen rheumatischen Krankheiten.

The urgency of spinal procedures for rheumatoid inflammatory disease is presented in three typical spinal involvements. Characteristic connections between rheumatoid arthritis and the cervical spine, spinal fractures in ankylosing spondylitis and the occurrence of bacterial spondylodiscitis as a side effect of immunosuppression are discussed.

Neural driven angiogenesis by overexpression of nerve growth factor.

Mechanisms regulating angiogenesis are crucial in adjusting tissue perfusion on metabolic demands. We demonstrate that overexpression of nerve growth factor (NGF) in brown adipose tissue (BAT) of NGF-transgenic mice elevates both mRNA and protein levels of vascular endothelial growth factor (VEGF) and VEGF-receptors. Increased vascular permeability, leukocyte-endothelial interactions (LEI), and tissue perfusion were measured using intravital microscopy. NGF-stimulation of adipocytes and endothelial cells elevates mRNA expression of VEGF and its receptors, an effect blocked by NGF neutralizing antibodies. These data suggest an activation of angiogenesis as a result of both: stimulation of adipozytes and direct mitogenic effects on endothelial cells. The increased nerve density associated with vessels strengthened our hypothesis that tissue perfusion is regulated by neural control of vessels and that the interaction between the NGF and VEGF systems is the critical driver for the activated angiogenic process. The interaction of VEGF- and NGF-systems gives new insights into neural control of organ vascularization and perfusion.

Femur window--a new approach to microcirculation of living bone in situ.

BACKGROUND: The processes of osteogenesis, bone remodelling, fracture repair and metastasis to bone are determined by complex sequential interactions involving cellular and microcirculatory parameters. Consequently studies targeting the analysis of microcirculatory parameters on such processes should mostly respect these complex conditions. However these conditions could not yet be achieved in vitro and therefore techniques that allow a long-term observation of functional and structural parameters of microcirculation in bone in vivo at a high spatial resolution are needed to monitor dynamic events, such as fracture healing, bone remodelling and tumor metastasis. METHODS: We developed a bone chamber implant (femur window) for long-term intravital microscopy of pre-existing bone and its microcirculation at an orthotopic site in mice preserving the mechanical properties of bone. After bone chamber implantation vascular density, vessel diameter, vessel perfusion, vascular permeability and leukocyte-endothelial interactions (LEIs) in femoral bone tissue of c57-black mice (n=11) were measured quantitatively over 12 days using intravital fluorescence microscopy. Furthermore a model for bone defect healing and bone metastasis in the femur window was tested. RESULTS: Microvascular permeability and LEIs showed initially high values after chamber implantation followed by a significant decrease to a steady state at day 6 and 12, whereas structural parameters remained unaltered. Bone defect healing and tumor growth was observed over 12 and 90 days respectively. CONCLUSION: The new femur window design allows a long-term analysis of structural and functional properties of bone and its microcirculation quantitatively at a high spatial resolution. Altered functional parameters of microcirculation after surgical procedures and their time dependent return to a steady state underline the necessity of long-term observations to achieve unaltered microcirculatory parameters. Dissection of the complex interactions between bone and microcirculation enables us to evaluate physiological and pathological processes of bone and may give new insights especially in dynamic events e.g. fracture healing, bone remodeling and tumor metastasis.

Met326Ile aminoacid polymorphism in the human p85 alpha gene has no major impact on early insulin signaling in type 2 diabetes.

Class I alpha phosphatidylinositol (PI) 3-kinase is an important enzyme in the early insulin signaling cascade, and plays a key role in insulin-mediated glucose transport. Despite extensive investigation, the genes responsible for the development of the common forms of type 2 diabetes remain unknown. This study was performed to identify variants in the coding region of p85 alpha, the regulatory subunit of PI 3-kinase. Fibroblasts from skin biopsies from type 2 diabetics and controls were established to address this issue. P85 alpha cDNA was sequenced, and a single point mutation at codon 326 was found. This mutation resulted in a homozygous missense amino acid change Met --> Ile in one subject with type 2 diabetes and heterozygous variant in two other diabetic patients and one with severe insulin resistance. Interestingly, those patients revealed an impaired insulin-mediated insulin receptor substrate (IRS)-1 binding to p85 alpha without any alteration in IRS-2/p85 alpha association. Furthermore, IRS-1, IRS-2, p85 alpha and MAPK protein contents were not significantly changed, and neither were MAPK or Akt phosphorylation. We conclude from our data that this variant may have only minor impact on signaling events; however, in combination with variants in other genes encoding signaling proteins, this may have a functional impact on early insulin signaling.

A new model of primary human adipocytes reveals reduced early insulin signalling in type 2 diabetes.

The aim of this study was to establish a diabetic model of primary human adipocytes for investigating potential defects in early insulin signalling. Specimens of human subcutaneous adipose tissue were obtained during orthopaedic surgical procedures. Preadipocytes were isolated and differentiated to adipocytes. Western blot analysis and immunoprecipitation were performed to determine protein content of IRS-1, IRS-2, p85, phosphorylation of IRS-1, IRS-2, Akt and MAPK as well as association between p85 and IRS-1/IRS-2. In addition to short-term insulin stimulation, the effect of hyperinsulinaemia was investigated by treating cells with insulin over a period of 36 hours. We found a significantly reduced basal expression of IRS-1 (54 +/- 15%) in adipocytes from type 2 diabetic subjects compared to controls with a further significant reduction in expression after long-term treatment (30 +/- 12%) compared to short-term treatment. IRS-2 expression also showed a significant reduction under hyperinsulinaemic conditions (20 +/- 2%) in diabetics vs. controls. Furthermore, long-term treatment with insulin in diabetic adipocytes led to a significant reduction in the phosphorylation of IRS-1(68 +/- 11%), IRS-2 (82 +/- 11%), Akt (42 +/- 2%), and MAPK (92 +/- 12%) and in the subsequent association between p85 to IRS-1 and IRS-2 (100 +/- 16% and 96 +/- 12%) in comparison to controls. Investigating glucose uptake diabetic adipocytes revealed a significant reduction of 90 +/- 2%. In this study, we were able to establish a new diabetic model of primary human adipocytes. A defect in early insulin signalling in type 2 diabetic patients under hyperinsulinaemic conditions was determined. These results might help to give further insights in early insulin action; additionally, this human model represents a useful target for the study of new therapeutic approaches.

Therapeutic dose of HIV-1 protease inhibitor saquinavir does not permanently influence early insulin signaling.

UNLABELLED: The introduction of HIV-1 protease inhibitor therapy has significantly improved the expectancy and quality of life for HIV-infected patients. Recent reports have highlighted the development of metabolic complications in patients taking protease inhibitors, including abnormalities in glucose metabolism such as impaired glucose tolerance and type 2 diabetes. The mechanisms by which protease inhibitors induce these metabolic syndromes are not well understood. The aim of this study was to determine whether treatment with the HIV-1 protease inhibitor, saquinavir, influences the early insulin signaling cascade in insulin-sensitive cell lines. METHODS: Insulin-stimulated phosphorylation of insulin receptor (IR-beta), insulin receptor substrates (IRS-1 and IRS-2), association of phosphatidylinositol 3-kinase (PI 3-kinase), Ser 473-phosphorylation of Akt and Thr202/Tyr204-phosphorylated p44/42 MAP kinase in 3T3L1 adipocytes and FAO hepatoma cells incubated with increasing concentrations of saquinavir for 24, 36 hours, 2, 3 and 6 days were measured. Results. Phosphorylation of IR-beta, IRS-1 and IRS-2 was not permanently affected by incubation with therapeutic doses (2.5 microM) of saquinavir for 36 hours. After 24 hours we observed an increase of IR-beta and IRS-1 phosphorylation. However, this initial stimulation of IR-beta and IRS-1 phosphorylation was not permanent and did not result in an increased PI 3-kinase association. Phosphorylation of IRS-2 and MAP kinase as well as glucose transport activity was not altered by therapeutic doses. Doses of 10, 25 and 50 microM of saquinavir altered the early insulin signaling events in a dose-dependent manner. However, this effect was primarily due to the cytotoxic effect of higher saquinavir doses. Glucose transport activity was not significantly reduced in 3T3L1 cells treated with 2.5 microM saquinavir in comparison to the control cells stimulated with insulin. CONCLUSION: Early insulin signaling cascade, essential for normal glucose metabolism, is not affected by therapeutic doses of saquinavir. The reduction of insulin-induced phosphorylation in higher concentrations is primarily related to cytotoxic effects. Other mechanisms than early insulin signaling must be primarily responsible for the metabolic alterations during saquinavir therapy.

Tumor oxygenation in hormone-dependent tumors during vascular endothelial growth factor receptor-2 blockade, hormone ablation, and chemotherapy.

Tumor oxygenation is critical for tumor survival as well as for response to therapy, e.g., radiation therapy. Hormone ablation therapy in certain hormone-dependent tumors and antiangiogenic therapy lead to vessel regression and have also shown beneficial effects when combined with radiation therapy. These findings are counterintuitive because vessel regression should reduce oxygen tension (pO2) in tumors, decreasing the effectiveness of radiotherapy. Here we report on the dynamics of pO2 and oxygen consumption in a hormone-dependent tumor following hormone ablation and during treatment with an anti-VEGFR-2 monoclonal antibody (mAb) or a combination of doxorubicin and cyclophosphamide; the latter combination is not known to cause vessel regression at doses used clinically. Androgen-dependent male mouse mammary carcinoma (Shionogi) was implanted into transparent dorsal skin-fold chambers in male severe combined immunodeficient mice. Thirteen days after the tumors were implanted, mice were treated with antiangiogenic therapy (anti-VEGFR-2 mAb, 1.4 mg/30 g body weight), hormone ablation by castration, or doxorubicin (6.5 mg/kg every 7 days) and cyclophosphamide (100 mg/kg every 7 days). A non-invasive in vivo method was used to measure pO2 profiles and to calculate oxygen consumption rates (Q(O2)) in tumors. Tumors treated with anti-VEGFR-2 mAb exhibited vessel regression and became hypoxic. Initial vessel regression was followed by a "second wave" of angiogenesis and increases in both pO2 and Q(O2). Hormone ablation led to tumor regression followed by an increase in pO2 coincident with regrowth. Chemotherapy led to tumor growth arrest characterized by constant Q(O2) and elevated pO2. The increased pO2 during anti-VEGFR-2 mAb and hormone ablation therapy may explain the observed beneficial effects of combining antiangiogenic or hormone therapies with radiation treatment. Thus, understanding the microenvironmental dynamics is critical for optimal scheduling of these treatment modalities.