Surgical instrumentation for the in vivo determination of human lumbar spinal segment stiffness and viscoelasticity

The definition of spinal instability is still controversial. For this reason, it is essential to better understand the difference in biomechanical behaviour between healthy and degenerated human spinal segments in vivo. A novel computer-assisted instrument was developed with the objective to characterize the biomechanical parameters of the spinal segment. Investigation of the viscoelastic properties as well as the dynamic spinal stiffness was performed during a minimally invasive procedure (microdiscectomy) on five patients. Measurements were performed intraoperatively and the protocol consisted of a dynamic part, where spinal stiffness was computed, and a static part, where force relaxation of the segment under constant elongation was studied. The repeatability of the measurement procedure was demonstrated with five replicated tests. The spinal segment tissues were found to have viscoelastic properties. Preliminary tests confirmed a decrease in stiffness after decompression surgery. Patients with non-relaxed muscles showed higher stiffness and relaxation rate compared to patients with relaxed muscles, which can be explained by the contraction and relaxation reflex of muscles under fast and then static elongation. The results show the usefulness of the biomechanical characterization of the human lumbar spinal segment to improve the understanding of the contribution of individual anatomical structures to spinal stability.     

Volumetric intravascular ultrasound imaging to illustrate the extent of coronary plaque burden in type 2 diabetic patients

BACKGROUND: Although angiography is the gold standard for coronary imaging, its efficacy in outlining diffuse coronary atherosclerosis in diabetic patients remains questionable. We aimed to compare quantitative cineangiographic analysis (QCA) with three-dimensional intravascular ultrasound (IVUS) imaging in type 2 diabetic patients with coronary artery disease. METHODS: IVUS runs of 104 significant coronary lesions in 88 diabetic patients were performed. Arterial remodeling index was calculated as vessel area at minimal lumen area divided by mean reference vessel area. RESULTS: No difference between the two analysis modes was shown for lesion length and minimal lumen diameter, whereas a significant discrepancy between QCA and IVUS was found for diameter stenosis (10 +/- 9% vs. 41 +/- 8%; P<.001) and vessel diameter (3.01 +/- 0.66 vs. 4.53 +/- 0.70 mm; P<.001). A significant difference on arterial remodeling at lesion site was found between insulin-treated diabetic patients and non-insulin-treated diabetic patients (remodeling index: 0.98 +/- 0.16 vs. 1.07 +/- 0.21; P=.04). CONCLUSIONS: Coronary angiographic diagnosis in diabetic patients may be distorted due to a large plaque burden over longer vessel segments and the resulting absence of plaque-free reference segments. This distortion was found to be more pronounced in QCA analysis requiring a reference diameter, whereas volumetric IVUS imaging illustrated coronary artery dimensions more accurately according to anatomic structures. Constrictive arterial remodeling was observed more frequently in type 2 diabetic patients treated with insulin.     

Differential diagnosis of benign and malign pancreatic masses with 18F-fluordeoxyglucose-positron emission tomography recorded with a dual-head coincidence gamma camera

INTRODUCTION: Metabolic imaging using 18F-fluordeoxyglucose and a ring-positron emission tomography camera is an established method in the differential diagnosis of pancreatic masses. Ring-positron emission tomography cameras, however, are expensive and available in only few specialized centres. The aim of this study was to investigate how far 18F-fluordeoxyglucose scan with a conventional dual-head gamma-camera could differentiate between benign and malign pancreatic masses. MATERIAL AND METHODS: Forty-one patients (male/female: 25/16; mean age: 64.0 years; range: 41-86 years) with a pancreatic mass detected by ultrasound, computed tomography or MRI were included. In all patients 18F-fluordeoxyglucose scan was performed after overnight fasting and injection of 4 mCi 18F-fluordeoxyglucose using an ADAC Vertex MCD dual head gamma-camera (ADAC; Milpitas, California, USA), equipped with a 5/8-inch NaI-crystal. Images were acquired through a 180 degrees grade rotation in the three dimensional mode. The chosen matrix was 128 x 128 x 16, a Butterworthfilter (ADAC) was used and data were transferred into visible sinograms via Fourier-Rebinning. Coronar, sagittal and transversal slices of 3.9 mm thickness each were acquired. Focal tracer enhancement was suspicious for a malignoma and therefore regarded as positive, diffuse or no tracer uptake was suspicious for a benign process and was regarded as negative for cancer. DEFINITION OF GOLD STANDARDS: A diagnosis of cancer had to be confirmed histologically by specimens obtained by 18G-needle biopsy, surgical resection or at autopsy. A diagnosis of an inflammatory mass was considered proven, if no carcinoma could be found histologically in the surgically resected mass or at autopsy, or if there was no progression of the disease during a follow-up of at least 12 months. RESULTS: In 22 patients carcinoma was diagnosed (pancreatic cancer: n=17; endocrine tumour: n=3; carcinoma of the common bile duct: n=2). 18F-fluordeoxyglucose scan showed a focal tracer enhancement in 19 of these 22 patients (sensitivity: 86.4%). False negative results were acquired in two patients with cancer of the common bile duct and in one patient with poorly controlled insulin-dependent diabetes mellitus. In 19 patients the final diagnosis was an inflammatory pancreatic mass. 18F-fluordeoxyglucose scan showed a diffuse tracer enhancement in 15 of these 19 patients (specificity: 78.9%). False positive results were acquired in three patients whose blood tests showed signs of an acute episode of chronic pancreatitis. Positive and negative predictive values of 18F-fluordeoxyglucose scan were 82.6% and 83.3%, respectively. CONCLUSION: 18F-fluordeoxyglucose scan with a conventional dual-head gamma-camera is a highly sensitive and specific method in the differential diagnosis of benign and malign pancreatic masses.     

The impact of early environmental rearing condition on the discriminative stimulus effects and Fos expression induced by cocaine in adult male and female rats

Rationale  A number of environmental manipulations, including maternal separation (MS), have been shown to alter behavioral responses to drugs of abuse. Objectives  This study assessed if MS affected the stimulus and Fos-inducing effects of cocaine. Materials and methods  In experiment 1, male and female Sprague–Dawley rats were exposed to brief maternal separations (BMS), long maternal separations (LMS), or animal facility rearing (AFR) and then trained as adults to discriminate cocaine (10 mg/kg, intraperitoneally) from saline. Following training, generalization tests to novel doses of cocaine and other dopaminergic compounds were performed. Assessments of variations in training dose pretreatment times were also made. In experiment 2, male and female rats exposed to MS conditions were administered cocaine or saline for 14 days, and Fos expression in the mesolimbic system was measured. Results  In males, BMS retarded the acquisition of the cocaine discrimination. Generalization to novel doses of cocaine did not differ among rearing conditions, but the training dose cue lasted longer in LMS. Distinct generalization and ED₅₀ profiles were found between male rearing conditions for all dopamine compounds. While BMS females had higher cocaine ED₅₀ estimates, no other differences were found in females. LMS males and females, as well as AFR females, had significant increases in Fos expression after cocaine in a region-specific manner. No differences were found with other rearing groups. Conclusion  Early environmental variables altered the stimulus effects (in a sex-dependent manner) as well as the neuronal responsiveness to cocaine, which may be mediated by the dopamine system.     

Reversal of acute renal failure by bortezomib-based chemotherapy in patients with multiple myeloma

Paraprotein induced renal failure is a frequent complication of multiple myeloma and is associated with poor survival. Previously, reversal of renal function has been hampered by the lack of fast acting and highly effective myeloma therapy and most patients remained or became dependent on hemodialysis. Here we show reversal of acute paraprotein-induced renal failure by bortezomib-based therapy in 5 out of 8 patients. Improvement of renal function was preceded by a significant reduction in paraprotein concentration in all patients, with improvement in renal function.