Material differentiation by dual energy CT: initial experience

The aim of this study was to assess the feasibility of a differentiation of iodine from other materials and of different body tissues using dual energy CT. Ten patients were scanned on a SOMATOM Definition Dual Source CT (DSCT; Siemens, Forchheim, Germany) system in dual energy mode at tube voltages of 140 and 80 kVp and a ratio of 1:3 between tube currents. Weighted CT Dose Index ranged between 7 and 8 mGy, remaining markedly below reference dose values for the respective body regions. Image post-processing with three-material decomposition was applied to differentiate iodine or collagen from other tissue. The results showed that a differentiation and depiction of contrast material distribution is possible in the brain, the lung, the liver and the kidneys with or without the underlying tissue of the organ. In angiographies, bone structures can be removed from the dataset to ease the evaluation of the vessels. The differentiation of collagen makes it possible to depict tendons and ligaments. Dual energy CT offers a more specific tissue characterization in CT and can improve the assessment of vascular disease. Further studies are required to draw conclusions on the diagnostic value of the individual applications.     

Catabolic Properties of Microdissected Human Endosteal Bone Lining Cells

Bone lining cells cover >80% of endosteal surfaces of human cancellous bone. Current research assigns to them a dual role: (1) as a biological membrane regulating exchange of substrates between the bone fluid compartment and the extracellular fluid of bone marrow and (2) as a signaling link between the osteocytic network as mechanical receptor and the osteoclastic cell pool for local induction of bone resorption. Furthermore, a catabolic role has been considered. We therefore examined the presence of matrix-metalloproteinases (MMPs) and their physiological tissue inhibitors (TIMPs) as putative proteolytic elements. Firstly, human cancellous bone from 60 patients was examined by immunofluorescence with antibodies against MMPs and TIMPs. Secondly, we applied laser-assisted microdissection (LMD) to isolate bone lining cells from frozen sections of human trabecular bone. mRNA analysis was performed using a single-cell PCR protocol. Three laser microdissection systems were tested: the new generation of Leica LMD and P.A.L.M. laser pressure catapulting (LPC) were compared to P.A.L.M. laser microdissection and micromanipulation (LMM). In a few pooled cell profiles, mRNA of MMP13, MMP14, TIMP1, and CBFA-1 was clearly detected. By immunofluorescence MMP13 and -14 as well as TIMP1 and -2 were strongly present in lining cells, while MMP2, TIMP3, and TIMP4 showed weak or negative signals. Although the functional impact of these enzymatic components remains open, there is additional evidence for a catabolic function of lining cells. The new diode-laser microdissection with LMD and LPC proved to be especially suitable to gain new insights into the properties of bone lining cells.     

Recent experience with percutaneous endoscopic gastrostomy/jejunostomy (PEG/J) for enteral nutrition

Background: Enteral feeding is the preferred means of nutritional support in patients unable to eat orally. Jejunal-placed feeding tubes are often considered optimal for this purpose. Successful administration of such tube feedings depends on the method of placement and the size of the tube. Herein we review our experience with endoscopically placed jejunal feeding tubes. Methods: Thirteen percutaneous endoscopic gastrostomy/jejunostomy (PEG/J) tubes were placed in 13 patients at the Emory University hospital by one surgeon. Indications for jejunal placement included aspiration in five patients and suspicion of increased reflux susceptibility in eight patients. Insertion of an 8.5-Fr nasobiliary tube was attempted in nine patients using the technique described by Coates and MacFadyen. A 12-Fr tube was placed in four patients using a technique that took advantage of previously placed PEG tubes. Results: Initial placement was successful in all but one patient. Nine tube-related complications occurred in seven patients. These included six tube occlusions, one tube site infection, one peristomal leak, and one tube perforation that required replacement. Five of six tube occlusions (83%) occurred in the smaller 8.5-Fr. tubes. There was one non–tube-related death. Conclusions: PEG/J insertion can be performed successfully and safely in most patients. Long-term tube patency is, however, dependent on the use of tubes with a large diameter; thus, modalities that enable placement of larger-sized tubes are preferable. Further technical developments are needed to facilitate the endoscopic insertion of larger jejunostomy tubes. Received: 1 May 1999/Accepted: 14 March 2000/Online publication: 25 April 2000     

Long-term mortality in patients with thrombosis of the inferior vena cava, iliac and femoral veins.

OBJECTIVES: To assess the long-term mortality in patients with thrombosis of the vena cava, iliac and femoral veins. DESIGN: Registry study. MATERIALS: Between 1992 and 2000, 212 consecutive patients with acute pelvic vein thrombosis diagnosed by duplex sonography were examined by magnetic resonance imaging (MRI) to determine the most proximal extent of the thrombus. MRI revealed a thrombosis in the inferior vena cava in 46 patients (22%), in the iliac vein in 142 patients (67%), and in the femoral vein in 24 patients (11%). METHODS: The vital status of the patients was investigated in April 2004 using the Austrian National Registry and the Cause of Death Register. RESULTS: A total of 211 patients of the original 212 patients were monitored over a mean follow-up period of 91 months. Seventy-two of 211 patients (34%) had died. There was no significant difference in the long-term mortality, the survival period or the occurrence of fatal pulmonary embolism (PE) between previously diagnosed vena cava, iliac vein, or femoral vein thrombosis. CONCLUSIONS: Extension of a thrombus into the inferior caval vein in patients considered to have a pelvic vein thrombosis has no impact on long-term mortality or the development of fatal PE compared to those patients with thrombus limited to more distal veins.     

Common bile duct calculi: updated experience with dissolution with methyl tertiary butyl ether

The authors describe their experience with methyl tertiary butyl ether (MTBE) in a larger series of patients than previously reported in order to acquaint physicians with both its effectiveness for dissolution of common bile duct calculi and the limitations of its use. Ten patients with 13 biliary calculi underwent percutaneous stone dissolution treatment with the experimental cholesterol solvent, MTBE. Three stones completely dissolved within 30 minutes, seven were reduced in size, and three were visibly unaffected. All stones not completely dissolved were easily extracted by means of a stone basket except for one in a patient taken to surgery. Although MTBE perfusion is an effective technique for management of biliary calculi, practitioners should be aware that its use is quite time consuming and its odor difficult to control.     

Superior fixation and less periprosthetic stress-shielding of tibial components with a finned stem versus an I-beam block stem: a randomized RSA and DXA study with minimum 5 years’ follow-up

Background and purpose — The stem on the tibial component of total knee arthroplasty provides mechanical resistance to lift-off, shear forces, and torque. We compared tibial components with finned stems (FS) and I-beam block stems (IS) to assess differences in implant migration.

Patients and methods — In a patient-blinded RCT, 54 patients/knees (15 men) with knee osteoarthritis at a mean age of 77 years (70–90) were randomly allocated to receive tibial components with either a FS (n = 27) or an IS (n = 27). Through 5 to 7 years’ follow-up, implant migration was measured with RSA, periprosthetic bone mineral density (BMD) was measured with DXA, and surgeons reported American Knee Society Score (AKSS).

Results — At minimum 5 years’ follow-up, maximum total point motion (MTPM) was higher (p = 0.04) for IS (1.48?mm, 95% CI 0.81–2.16) than for FS (0.85?mm, CI 0.38–1.32) tibial components. Likewise, total rotation (TR) was higher (p = 0.03) for IS (1.51?, CI 0.78–2.24) than for FS (0.81?, CI 0.36–1.27). Tibial components with IS externally rotated 0.50° (CI –0.06 to 1.06) while FS internally rotated 0.09° (CI –0.20 to 0.38) (p = 0.03). Periprosthetic bone stress-shielding was higher (p < 0.01) up to 2 years’ follow-up for IS compared with FS in the regions medial to the stem (–13% vs. –2%) and posterior to the stem (–13% vs. –2%). Below the stem bone loss was also higher (p = 0.01) for IS compared with FS (–6% vs. +1%) up to 1-year follow-up. Knee score improved similarly in both groups up to 5 years’ follow-up.

Interpretation — Periprosthetic bone stress-shielding medial and posterior to the stem until 2 years, and tibial component migration at 5 years, was less for a finned compared with an I-shaped block stem design.

Trial registration: ClinicalTrials.gov identifier: NCT00175136.     

Stimulus-dependent changes of extracellular glucose in the rat hippocampus determined by in vivo microdialysis

Neuronal activity is tightly coupled with brain energy metabolism; and glucose is an important energy substrate for neurons. The present in vivo microdialysis study was aimed at investigating changes in extracellular glucose concentrations in the rat ventral hippocampus due to exposure to the elevated plus maze. Determination of basal hippocampal glucose and lactate/pyruvate ratio in male Wistar rats was conducted in the home cage using in vivo microdialysis. Rats were exposed to the elevated plus maze, a rodent model of anxiety-related behaviour, or to unspecific stress induced by white noise (95 dB) as a control condition.Basal hippocampal levels of glucose, as determined by zero-net-flux, and the basal lactate/pyruvate ratio were 1.49 ± 0.05 mmol/l and 13.8 ± 1.1, respectively.In rats without manipulation, glucose levels remained constant throughout the experiment (120 min). By contrast, exposure to the elevated plus maze led to a temporary decline in hippocampal glucose (− 33.2 ± 4.4%) which returned to baseline level in the home cage. White noise caused only a non-significant decrease in extracellular glucose level (− 9.3 ± 3.5%). In all groups, the lactate/pyruvate ratio remained unchanged by the experimental procedures. Our microdialysis study demonstrates that exposure to the elevated plus maze induces a transient decrease in extracellular hippocampal glucose concentration. In contrast, an unspecific stimulus did not change hippocampal glucose. The latter suggests that only specific behavioural stimuli increase hippocampal glucose utilization in the ventral hippocampus.     

Work satisfaction and career aspirations of internists working in teaching hospital group practices

This paper presents data on the characteristics, work activities, job-related stress, work satisfaction, and career aspirations of 150 faculty and 595 housestaff physicians who regularly provide continuous primary care in 15 teaching hospital-based group practices. The faculty were young, board-certified generalists; they had been recruited from local training programs and spent the majority of their time seeing patients and supervising housestaff. Job satisfaction among faculty and housestaff was generally high. Dissatisfaction occurred most often with aspects of work over which physicians had little control. Although work-related stress was common, it was not related to job satisfaction. Compared with housestaff in traditional residency programs, housestaff enrolled in special Primary Care Training Programs reported significantly greater job satisfaction. For all housestaff, satisfaction with work in the group practice was consistently associated with decreased interest in subspecialty training. assisted in preparing this report. Received from the Department of Medicine and the School of Public Health, UCLA Center for the Health Sciences. Los Angeles. California. Supported by Grant #59082 from the Robert Wood Johnson Foundation. The views expressed herein do not necessarily represent those of the Robert Wood Johnson Foundation.