Screening for hepatocellular carcinoma among adults with HIV/HBV co-infection in Zambia: a pilot study

BACKGROUND AND AIMS

Chronic hepatitis B virus (HBV) infection is the main cause of hepatocellular carcinoma (HCC) in sub-Saharan Africa (SSA). An HCC screening initiative was piloted in an established cohort of individuals co-infected with human immunodeficiency virus (HIV) and HBV on antiretroviral therapy (ART) at two outpatient clinics in Lusaka, Zambia.

METHODS

All patients underwent abdominal ultrasound (AUS) and transient elastography.

RESULTS

Among 279 patients co-infected with HIV/HBV, 165 (59.1%) were men, median age was 34 years [interquartile range (IQR) 28-39 years] and median CD4 count was 246 cells/µL (IQR 112-355 cells/µL) at ART initiation. While 102 (55.7%) individuals had elevated transaminases, 114 (59.7%) had HBV levels >2000 IU/mL and 59 (24.6%) had significant fibrosis. At their first AUS measurement, 75 (26.9%) participants had hepatomegaly and 69 (24.7%) had periportal fibrosis. Five patients had a liver lesion >1 cm, an indication for confirmatory imaging.

CONCLUSIONS

In one of the first HCC screening initiatives in SSA, 2% of patients co-infected with HIV/HBV had significant liver lesions, and one-quarter had findings suggestive of schistosomiasis-induced liver damage.

Value of MRI/CT Image Fusion for Targeting "invisible" Lesions in Stereotactic Microwave Ablation (SMWA) of Malignant Liver Lesions: A Retrospective Analysis

PURPOSE

To assess the technical feasibility of MRI/CT image fusion and completeness of ablation treatment for primary or metastatic liver lesions invisible on contrast-enhanced CT planning scans and outcome in patients treated with stereotactic microwave ablation (SMWA).

MATERIALS AND METHODS

The study was approved by the local ethics committee. Patients who underwent SMWA between January 2015 and December 2018 were retrospectively analyzed. All liver lesions for which MRI/CT fusion was performed due to invisibility on pre-interventional CT planning scans were included and reassessed. The outcome measurement was successful ablation of the lesion at first follow-up imaging.

RESULTS

During the study period, 236 patients underwent 312 SMWAs with ablation of 496 lesions. Twenty-four lesions in 15 patients (mean age, 62 years; range, 43-80 years) were included. Following MRI/CT image fusion, all 24 lesions could be sufficiently localized to perform SMWA. The first follow-up imaging showed complete ablation of 22 lesions. Two initially incompletely ablated lesions were hepatocellular carcinomas and were successfully re-ablated afterwards.

CONCLUSION

SMWA with MRI/CT image fusion is an accurate and safe treatment option for patients with liver lesions not detectable on contrast-enhanced CT planning scans. MRI/CT image fusion may allow more patients with malignant liver lesions to benefit from local ablation treatment even if their lesions are not visible on CT planning examinations.

MRI of cystic fibrosis lung manifestations: sequence evaluation and clinical outcome analysis

AIM

To evaluate different magnetic resonance imaging (MRI) sequences for diagnosis of pulmonary manifestations of cystic fibrosis (CF) in comparison to chest computed tomography (CT), including an extended outcome analysis.

MATERIALS AND METHODS

Twenty-eight patients with CF (15 male, 13 female, mean age 30.5±9.4 years) underwent CT and MRI of the lung. MRI (1.5 T) included different T2- and T1-weighted sequences: breath-hold HASTE (half Fourier acquisition single shot turbo spin echo) and VIBE (volumetric interpolated breath-hold examination, before and after contrast medium administration) sequences and respiratory-triggered PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) sequences with and without fat signal suppression, and perfusion imaging. CT and MRI images were evaluated by the modified Helbich and the Eichinger scoring systems. The clinical follow-up analysis assessed pulmonary exacerbations within 24 months.

RESULTS

The highest concordance to CT was achieved for the PROPELLER sequences without fat signal suppression (concordance correlation coefficient CCC of the overall modified Helbich score 0.93 and of the overall Eichinger score 0.93). The other sequences had the following concordance: PROPELLER with fat signal suppression (CCCs 0.91 and 0.92), HASTE (CCCs 0.87 and 0.89), VIBE (CCCs 0.84 and 0.85) sequences. In the outcome analysis, the combined MRI analysis of all five sequences and a specific MRI protocol (PROPELLER without fast signal suppression, VIBE sequences, perfusion imaging) reached similar correlations to the number of pulmonary exacerbations as the CT examinations.

CONCLUSION

An optimum lung MRI protocol in patients with CF consists of PROPELLER sequences without fat signal suppression, VIBE sequences, and lung perfusion analysis to enable high diagnostic efficacy and outcome prediction.

Activity-based cost analysis of hepatic tumor ablation using CT-guided high-dose rate brachytherapy or CT-guided radiofrequency ablation in hepatocellular carcinoma

Purpose

To analyse and compare the costs of hepatic tumor ablation with computed tomography (CT)-guided high-dose rate brachytherapy (CT-HDRBT) and CT-guided radiofrequency ablation (CT-RFA) as two alternative minimally invasive treatment options of hepatocellular carcinoma (HCC).

Materials and methods

An activity based process model was created determining working steps and required staff of CT-RFA and CT-HDRBT. Prorated costs of equipment use (purchase, depreciation, and maintenance), costs of staff, and expenditure for disposables were identified in a sample of 20 patients (10 treated by CT-RFA and 10 by CT-HDRBT) and compared. A sensitivity and break even analysis was performed to analyse the dependence of costs on the number of patients treated annually with both methods.

Results

Costs of CT-RFA were nearly stable with mean overall costs of approximately 1909 €, 1847 €, 1816 € and 1801 € per patient when treating 25, 50, 100 or 200 patients annually, as the main factor influencing the costs of this procedure was the single-use RFA probe. Mean costs of CT-HDRBT decreased significantly per patient ablation with a rising number of patients treated annually, with prorated costs of 3442 €, 1962 €, 1222 € and 852 € when treating 25, 50, 100 or 200 patients, due to low costs of single-use disposables compared to high annual fix-costs which proportionally decreased per patient with a higher number of patients treated annually. A break-even between both methods was reached when treating at least 55 patients annually.

Conclusion

Although CT-HDRBT is a more complex procedure with more staff involved, it can be performed at lower costs per patient from the perspective of the medical provider when treating more than 55 patients compared to CT-RFA, mainly due to lower costs for disposables and a decreasing percentage of fixed costs with an increasing number of treatments.

Ultra-low-dose dual-source CT coronary angiography with high pitch: diagnostic yield of a volumetric planning scan and effects on dose reduction and imaging strategy

OBJECTIVE

To evaluate the role of an ultra-low-dose dual-source CT coronary angiography (CTCA) scan with high pitch for delimiting the range of the subsequent standard CTCA scan.

METHODS

30 patients with an indication for CTCA were prospectively examined using a two-scan dual-source CTCA protocol (2.0 × 64.0 × 0.6 mm; pitch, 3.4; rotation time of 280 ms; 100 kV): Scan 1 was acquired with one-fifth of the tube current suggested by the automatic exposure control software [CareDose 4D™ (Siemens Healthcare, Erlangen, Germany) using 100 kV and 370 mAs as a reference] with the scan length from the tracheal bifurcation to the diaphragmatic border. Scan 2 was acquired with standard tube current extending with reduced scan length based on Scan 1. Nine central coronary artery segments were analysed qualitatively on both scans.

RESULTS

Scan 2 (105.1 ± 10.1 mm) was significantly shorter than Scan 1 (127.0 ± 8.7 mm). Image quality scores were significantly better for Scan 2. However, in 5 of 6 (83%) patients with stenotic coronary artery disease, a stenosis was already detected in Scan 1 and in 13 of 24 (54%) patients with non-stenotic coronary arteries, a stenosis was already excluded by Scan 1. Using Scan 2 as reference, the positive- and negative-predictive value of Scan 1 was 83% (5 of 6 patients) and 100% (13 of 13 patients), respectively.

CONCLUSION

An ultra-low-dose CTCA planning scan enables a reliable scan length reduction of the following standard CTCA scan and allows for correct diagnosis in a substantial proportion of patients.

ADVANCES IN KNOWLEDGE

Further dose reductions are possible owing to a change in the individual patient's imaging strategy as a prior ultra-low-dose CTCA scan may already rule out the presence of a stenosis or may lead to a direct transferal to an invasive catheter procedure.

MRI-guided and CT-guided cervical nerve root infiltration therapy: a cost comparison

PURPOSE

To evaluate and compare the costs of MRI-guided and CT-guided cervical nerve root infiltration for the minimally invasive treatment of radicular neck pain.

MATERIALS AND METHODS

Between September 2009 and April 2012, 22 patients (9 men, 13 women; mean age: 48.2 years) underwent MRI-guided (1.0 Tesla, Panorama HFO, Philips) single-site periradicular cervical nerve root infiltration with 40 mg triamcinolone acetonide. A further 64 patients (34 men, 30 women; mean age: 50.3 years) were treated under CT fluoroscopic guidance (Somatom Definition 64, Siemens). The mean overall costs were calculated as the sum of the prorated costs of equipment use (purchase, depreciation, maintenance, and energy costs), personnel costs and expenditure for disposables that were identified for MRI- and CT-guided procedures. Additionally, the cost of ultrasound guidance was calculated.

RESULTS

The mean intervention time was 24.9 min. (range: 12 - 36 min.) for MRI-guided infiltration and 19.7 min. (range: 5 - 54 min.) for CT-guided infiltration. The average total costs per patient were EUR 240 for MRI-guided interventions and EUR 124 for CT-guided interventions. These were (MRI/CT guidance) EUR 150/60 for equipment use, EUR 46/40 for personnel, and EUR 44/25 for disposables. The mean overall cost of ultrasound guidance was EUR 76.

CONCLUSION

Cervical nerve root infiltration using MRI guidance is still about twice as expensive as infiltration using CT guidance. However, since it does not involve radiation exposure for patients and personnel, MRI-guided nerve root infiltration may become a promising alternative to the CT-guided procedure, especially since a further price decrease is expected for MRI devices and MR-compatible disposables. In contrast, ultrasound remains the less expensive method for nerve root infiltration guidance.

Optical imaging of breast cancer using hemodynamic changes induced by valsalva maneuver

PURPOSE

To investigate whether changes in hemodynamics induced by Valsalva maneuver can be exploited for detecting and characterizing breast lesions by optical mammography.

MATERIALS AND METHODS

30 women underwent optical imaging of the breast using a DYNOT 232 system and performing Valsalva maneuvers prior to biopsy. Changes in light absorption due to changes in oxyhemoglobin and deoxyhemoglobin concentrations were recorded volumetrically and in a time-resolved manner. The parameters full width at half maximum (FWHM), time to ten (TTT), and peak amplitude (PA) of the reconstructed concentration time curves yielded color-coded maps of the breast which were separately evaluated by two experienced readers for detection rate, degree of visibility, and detection of additional lesions. ROC analysis was performed with the evaluation results.

RESULTS

10 patients were excluded from analysis due to artifacts or inadequately performed Valsalva maneuver. The resulting 20 patients showed a clear increase in oxygenated and deoxygenated hemoglobin concentration after the onset of the Valsalva maneuver. ROC analysis yielded AUC values (0.393 - 0.779) that did not differ from random probabilities. The highest AUC values were obtained for FWHM (AUC: 0.779, detection rates [60 - 70 %], identification of additional lesions [55 - 70 %]). PA analysis had the highest detection rate (70 - 90 %) but also the highest identification of false-positive additional lesions (80 - 90 %). The concordance rates of the two readers for malignant lesions were satisfactory (0.524 - 1.0).

CONCLUSION

Our study revealed susceptibility to artifacts and a large number of false-positive additional lesions, suggesting that the evaluation of hemodynamic changes after Valsalva maneuver by optical imaging is not a promising method.

Cost comparison of nerve root infiltration of the lumbar spine under MRI and CT guidance

OBJECTIVES

To compare the costs of CT- and MR-guided lumbosacral nerve root infiltration for minimally invasive treatment of low back pain and radicular pain.

METHODS

Ninety patients (54 men, 36 women; mean age, 45.5 ± 12.8 years) underwent MR-guided single-site periradicular lumbosacral nerve root infiltration with 40 mg of triamcinolone acetonide. A further 91 patients (48 men, 43 women; mean age, 59.1 ± 13.8 years) were treated under CT fluoroscopy guidance. Prorated costs of equipment use (purchase, depreciation and maintenance), staff costs based on involvement times and expenditure for disposables were identified for MR- and CT-guided procedures.

RESULTS

Mean intervention time was 20.6 min (14-30 min) for MR-guided and 14.3 min (7-32 min) for CT-guided treatment. The average total costs per patient were €177 for MR-guided and €88 for CT-guided interventions. These consisted of (MR/CT guidance) €93/29 for equipment use, €43/35 for staff and €41/24 for disposables.

CONCLUSIONS

Lumbosacral nerve root infiltration using MRI guidance is still about twice as expensive as infiltration using CT guidance. Given the advantages of no radiation exposure and possible future decrease in prices for MRI devices and MR-compatible injection needles, MR-guided nerve root infiltration may become a promising alternative to the CT-guided procedure.

KEY POINTS

• MR-guided nerve root infiltration therapy is now technically and clinically established. • Costs using MRI guidance are still about double those for CT guidance. • MR guidance involves no radiation exposure to patients and personnel. • MR-guided nerve root infiltration may become a promising alternative to CT.

Glioblastoma multiforme versus solitary supratentorial brain metastasis: differentiation based on morphology and magnetic resonance signal characteristics

PURPOSE

To evaluate the diagnostic potential of a multi-factor analysis of morphometric parameters and magnetic resonance (MR) signal characteristics of a mass and peritumoral area to distinguish solitary supratentorial metastasis from glioblastoma multiforme (GBM).

MATERIALS AND METHODS

MR examinations of 51 patients with histologically proven GBM and 44 with a single supratentorial metastasis were evaluated. A large variety of morphologic criteria and MR signal characteristics in different sequences were analyzed. The data were subjected to logistic regression to investigate their ability to discriminate between GBM and cerebral metastasis. Receiver-operating characteristic (ROC) analysis was used to select an optimal cut-off point for prediction and to assess the predictive value in terms of sensitivity, specificity, and accuracy of the final model.

RESULTS

The logistic regression analysis revealed that the ratio of the maximum diameter of the peritumoral area measured on T2-weighted images (d T2) to the maximum diameter of the enhancing mass area (d T1, post-contrast) is the only useful criterion to distinguish single supratentorial brain metastasis from GBM with a lower ratio favoring GBM (accuracy 68 %, sensitivity 84 % and specificity 45 %). The cut-off point for the ratio d T2/d T1 post-contrast was calculated as 2.35.

CONCLUSION

Measurement of maximum diameters of the peritumoral area in relation to the enhancing mass can be evaluated easily in the clinical routine to discriminate GBM from solitary supratentorial metastasis with an accuracy comparable to that of advanced MRI techniques.

[The balanced scorecard--applications in a radiology department]

The balanced scorecard (BSC) represents a comprehensive management tool for organizations with the aim to focus all activities on a chosen strategy. Targets for various perspectives of the environment such as the customer, financial, process, and potential perspective are linked with concrete measures, and cause-effect relationships between the objectives are analyzed. This article shows that the BSC can also be used for the comprehensive control of a radiology department and thus provides a meaningful contribution in organizing the various diagnostic and treatment services, the management of complex clinical environment and can be of help with the tasks in research and teaching.

Treatment of osteoid osteoma using CT-guided radiofrequency ablation versus MR-guided laser ablation: a cost comparison

OBJECTIVE

To compare the costs of CT-guided radiofrequency ablation (RFA) and MR-guided laser ablation (LA) for minimally invasive percutaneous treatment of osteoid osteoma.

MATERIALS AND METHODS

Between November 2005 and October 2011, 20 patients (14 males, 6 females, mean age 20.3±9.1 years) underwent CT-guided RFA and 24 patients (18 males, 6 females; mean age, 23.8±13.8 years) MR-guided LA (open 1.0 Tesla, Panorama HFO, Philips, Best, Netherlands) for osteoid osteoma diagnosed on the basis of clinical presentation and imaging findings. Prorated costs of equipment use (purchase, depreciation, and maintenance), staff costs, and expenditure for disposables were identified for CT-guided RFA and MR-guided LA procedures.

RESULTS

The average total costs per patient were EUR 1762 for CT-guided RFA and EUR 1417 for MR-guided LA. These were (RFA/LA) EUR 92/260 for equipment use, EUR 149/208 for staff, and EUR 870/300 for disposables.

CONCLUSION

MR-guided LA is less expensive than CT-guided RFA for minimally invasive percutaneous ablation of osteoid osteoma. The higher costs of RFA are primarily due to the higher price of the disposable RFA probes.

[Targeted methods for measuring patient satisfaction in a radiological center]

PURPOSE

To investigate two event-oriented methods for evaluating patient satisfaction with radiological services like outpatient computed tomography (CT) examinations.

MATERIALS AND METHODS

159 patients (55% men, 45% women) were asked to complete a questionnaire to provide information about their satisfaction with their examination. At first, patients were asked to spontaneously recall notably positive and negative aspects (so-called "critical incidents", critical incident technique = CIT) of the examination. Subsequently a flow chart containing all single steps of the examination procedure was shown to all patients. They were asked to point out the positive and negative aspects they perceived at each step (so-called sequential incident technique = SIT).

RESULTS

The CIT-based part of the questionnaire yielded 356 comments (183 positive and 173 negative), which were assigned to one of four categories: interaction of staff with patient, procedure and organization, CT examination, and overall setting of the examination. Significantly more detailed comments regarding individual aspects of the CT examination were elicited in the second part of the survey, which was based on the SIT. There were 1413 statements with a significantly higher number of positive comments (n = 939, 66%) versus negative comments (n = 474, 34%; p < 0.001).

CONCLUSION

The critical and sequential incident techniques are suitable to measure the subjective satisfaction with the delivery of radiological services such as CT examinations. Positive comments confirm the adequacy of the existing procedures, while negative comments provide direct information about how service quality can be improved.

High prevalence of the NBN gene mutation c.657-661del5 in Southeast Germany

Nijmegen breakage syndrome (NBS), a rare autosomal recessive chromosomal instability disorder, is caused by mutations in the NBN gene. Most patients known so far are of Slavic origin and carry the major founder mutation c.657-661del5. Due to an unexpectedly high incidence of NBS patients (homozygous for the c.657-661del5 mutation) in a Northeast Bavarian region in Southeast Germany, we estimated the prevalence of this mutation in this area and compared it to another German region. We found a high carrier frequency of 1/176 for the c.657-661del5 mutation among newborns in Northeast Bavaria, while the frequency of the mutation in Berlin was 1/990. We further studied families from a Slavic population isolate, the Sorbs, in the Lusatian region in Northeast Saxony, and revealed a prevalence of the c.657-661del5 mutation of 1/34. Whereas the Slavic origin of the Sorbs has been known, we attribute the surprisingly high frequencies of c.657-661del5 mutation in Bavaria (similar to frequencies of this mutation in various Eastern European countries) to a high percentage of people of Slavic origin in Northeast Bavaria.

Survey regarding the clinical practice of cardiac CT in Germany: indications, scanning technique and reporting

PURPOSE

To obtain an overview of the current clinical practice of cardiac computed tomography (CT) in Germany.

MATERIALS AND METHODS

A 30-item questionnaire was mailed to 149 providers of cardiac CT in Germany. The items asked about indications, scanning technique and reporting, data storage, and cost of the examination.

RESULTS

Overall 45 questionnaires could be analyzed (30 %). The majority of centers (76 %, 34 of 45 centers) used CT scanners of the latest generation (at least 64 rows). The most common appropriate indications were exclusion of coronary artery disease (91 %, 41 / 45), coronary anomalies (80 %, 36 / 45), and follow-up after coronary artery bypass grafting (53 %, 24 / 45). Each center examined on average 243 +/- 310 patients in 2007 and the number of centers performing cardiac CT increased significantly in 2007 (p = 0.035) compared with the preceding year. Most used sublingual nitroglycerin (84 %, 38 / 45; median of 2 sprays = 0.8 mg) and/or a beta blocker (86 %, 39 / 44; median of 5 mg IV, median heart rate threshold: 70 beats/min). Many providers used ECG-triggered tube current modulation (65 %, 29 / 44) and/or adjusted the tube current to the body mass index or body weight (63 %, 28 / 44). A median slice thickness of 0.75 mm with a 0.5 mm increment and a 20 cm field-of-view was most commonly used. Source images in orthogonal planes (96 %, 43 / 45), curved MPRs (93 %, 42 / 45), and thin-slice MIPs (69 %, 31 / 45) were used most frequently for interpretation. Extracardiac structures were also evaluated by 84 % of the centers (38 / 45). The mean examination time was 16.2 min and reporting took an average of 28.8 min.

CONCLUSION

Cardiac CT has rapidly become an established procedure with standards regarding indications, scanning technique, and reporting.

Old friends in new constellations--the hematopoetic growth factors G-CSF, GM-CSF, and EPO for the treatment of neurological diseases

Currently, growth factors which have been identified in hematopoiesis and angiogenesis are re-considered as therapeutical agents in a number of neurological diseases, mainly neurodegenerative disorders like Parkinson's Disease, amyotrophic lateral sclerosis (ALS), or cerebrovascular events such as stroke. Among these growth factors, erythropoietin (EPO) and granulocyte colony-stimulating growth factor (G-CSF) are the most prominent. With regard to neurological disease, EPO has been tested in clinical trials for potential use in stroke, schizophrenia, and addiction, G-CSF is currently under clinical investigation for stroke treatment. The major advantage of these growth factors is their well-described pharmacological behavior and their clinical use over several years. A number of mechanisms of action in the CNS have been identified that are probably important for the beneficial action of these factors in animal models of disease, the most relevant relating to neuroprotection, neuroplasticity and stem cell growth and differentiation. In this review, we will discuss the current efforts and prerequisites of novel growth factor therapies for neurodegenerative diseases with regard to their possible mechanism of action on the molecular level and their effects on brain-derived stem cell populations. Additionally, we will describe the necessities for future research before such therapies can be envisioned.

Spatial learning induces predominant downregulation of cytosolic proteins in the rat hippocampus

Spatial learning is known to depend on protein synthesis in the hippocampus. Whereas the role of the hippocampus in spatial memory is established, the biochemical and molecular mechanisms underlying this process are poorly understood. To comprehend the complex pattern of protein expression induced by spatial learning, we analyzed alterations in the rat hippocampus proteome after 7 days of spatial learning in the Morris water maze. Forty Wistar rats were randomized into two groups. Animals of group A learned to localize a hidden platform in the water maze. Animals of group B served as controls and spent exactly the same time in the water maze as animals of group A. However, no platform was used in this test and the rats could not learn to localize the target. After the last trial, hydrophilic proteins from the hippocampus were isolated. A proteome-wide study was performed, based on two-dimensional gel electrophoresis and mass spectrometry. Compared with non-learning animals, 53 (70%) proteins were downregulated and 23 (30%) proteins were upregulated after 7 days in rats with spatial learning. The overall changes in protein expression, as quantified by the induction factor, ranged from -1.62 (downregulation to 62%) to 2.10 (upregulation by 110%) compared with controls (100%). Most identified proteins exhibit known functions in vesicle transport, cytoskeletal architecture, and metabolism as well as neurogenesis. These findings indicate that learning in the Morris water maze has a morphological correlate on the proteome level in the hippocampus.

Volatile anesthetics evoke prolonged changes in the proteome of the left ventricule myocardium: defining a molecular basis of cardioprotection?

BACKGROUND

Volatile anesthetics can alter cardiac gene and protein expression. Of those underlying molecular changes in gene and protein expression in the myocardium after exposure to volatile anesthetics that have been identified, some of them have been related to cardioprotection.

METHODS

We used two-dimensional gel electrophoresis and mass spectrometry to identify changes in the protein expression of the left ventricle myocardium of anesthesized rats. We maintained anesthesia for 3 h using isoflurane, sevoflurane or desflurane, respectively, at 1.0 minimum alveolar concentration (MAC) and dissected the left ventricular myocardium either immediately or 72 h after the end of anesthesia.

RESULTS

We found changes of at least twofold in 106 proteins of the more than 1.600 protein spots discriminated in each gel. These differentially expressed proteins are associated with functions in glycolysis, mitochondrial respiration and stress response. No obvious difference could be observed between the patterns of differential expression of the three volatile anesthetics.

CONCLUSION

We provide the first study of post-anesthetic protein expression profiles associated with three common volatile anesthetics. These volatile anesthetics promote a distinct change in the myocardial protein expression profile, whereby changes in the expression pattern still exist 72 h after anesthesia. These proteome changes are closely related to cardioprotection and ischemic preconditioning, indicating a common functional signaling of volatile anesthestics.

Zerebrale Mikrodialyse beim Schlaganfall

Cerebral microdialysis is an invasive technique for neurochemical monitoring that has been established for neuro-critical disorders such as subarachnoid hemorrhage and severe brain injury. We present data on cerebral microdialysis in stroke patients which were obtained in an ongoing study supported by the German Ministry for Education and Research. So far, 50 patients have been included who required critical care due to massive stroke of the middle cerebral artery territory. By correlating the microdialysis results with follow-up CT scans, we could define the neurochemical characteristics of three different brain compartments: (1) noninfarcted brain tissue with normal microdialysis values, (2) brain areas adjacent to the infarct core which were not hypodense in CT scans but caused reversible neurochemical alterations, and (3) the infarct core with massive concentration changes which did not normalize over the measuring period of 3 to 5 days. Microdialysis values averaged over time and correlated with initial PET scans helped to describe neurochemical predictors of a malignant, i.e., life-threatening, space-occupying course of the ischemic stroke. We discuss the value of this method in guiding therapy and predicting clinical outcome in the context of other neurological critical care disorders and describe the pros and cons of cerebral microdialysis as an invasive monitoring technique.

Correlation between local glucose transporter densities and local 3-O-methylglucose transport in rat brain

The present study addresses the question whether local glucose transport kinetics are correlated with local glucose transporter densities in the brain. In 47 brain structures the local rate constants for 3-O-[(14)C]methylglucose (3-O-MG) transport, K(1) and k(2,) were quantified, and local glucose Glut1 and Glut3 transporter densities were determined by immuno-autoradiographic methods. Statistically significant correlations were found between the rate constants for glucose transport and the transporter densities. The correlations were tighter for Glut1 than for Glut3. Inasmuch as 3-O-MG is transported by the same transporter as glucose, these results indicate that the local densities of glucose transporters determine local glucose transport rates in the brain.

Increased cerebral glucose utilization and decreased glucose transporter Glut1 during chronic hyperglycemia in rat brain

Whereas acute hyperglycemia has been shown to result in an unchanged local cerebral glucose utilization (LCGU) the changes of LCGU during chronic hyperglycemia are a matter of dispute. The present study had three aims: (1) To compare the effects of acute and chronic hyperglycemia on LCGU and to investigate in vivo the lactate level as a potential indicator of glycolytic flux. (2) To investigate local changes in brain Glut1 and/or Glut3 glucose transporter densities during chronic hyperglycemia. (3) To analyze the relationship between LCGU and local Glut densities during chronic hyperglycemia. To induce chronic hyperglycemia in rats steptozotocin was given i.p. and experiments were performed 3 weeks later. LCGU was measured by the 2-[14C]deoxyglucose method and intraparenchymal lactate concentration by MR-spectroscopy. Local densities of the glucose transport proteins were determined by immunoautoradiographic methods. During chronic hyperglycemia weighted average of LCGU increased by 13.9% whereas it remained unchanged during acute hyperglycemia. The cerebral lactate/choline ratio was increased by 143% during chronic hyperglycemia. The average density of glucose transporters Glut1 decreased by 7.5%. Local densities of Glut1 were decreased in 12 of 28 brain structures. Glut3 remained unchanged. Positive correlations were found between LCGU and local Glut densities during control conditions and during chronic hyperglycemia. It was concluded that (1) Chronic, but not acute hyperglycemia is followed by an increased LCGU. (2) The capacity to transport glucose is decreased during chronic hyperglycemia. (3) Increased LCGU and decreased densities of Glut1 are matched on a local level.

Brain water content, glucose transporter densities and glucose utilization after 3 days of water deprivation in the rat

After 3 days of water deprivation, the following parameters were measured in rats: (i) brain water content (apparent diffusion coefficient); (ii) local cerebral glucose utilization (LCGU) ([14C]deoxyglucose method) and (iii) densities of glucose transporters Glut1 and Glut3 (immunoautoradiography). The results show that brain water content is maintained after water deprivation. Densities of glucose transporters Glut1 and Glut3 increased in parallel to increased LCGU in some of the osmoregulatory structures indicating a long-term local adaptation of glucose transporters to LCGU.

Local transport kinetics of glucose during acute and chronic nicotine infusion in rat brains

Acute and chronic infusion of nicotine is known to result in a distinct increase in local cerebral glucose utilization (LCGU) in several brain structures. The present study addresses the question whether this increase in LCGU is paralleled by a local change in glucose transport in rat brain. Nicotine was infused either acutely for 3 hours or chronically by osmotic minipumps for one week. Local rate constants for glucose transport were measured in brain cryosections using the 3-O-[14C]methylglucose method. Local rate constants K1 and k2 were lower in part of the brain structures during acute (-10% to -20%) and in nearly all structures during chronic (-39% to -41%) nicotine. The finding of a decreased glucose transport during chronic nicotine was confirmed by additional experiments of 3-O-[14C]methylglucose transfer in an epithelial cell culture. It is concluded that acute and chronic nicotine infusion results in decreased glucose transport although LCGU is either unchanged or increased.

Decreased glucose transporter densities, rate constants and glucose utilization in visual structures of rat brain during chronic visual deprivation

The question was investigated whether local changes in glucose transporter densities and transport kinetics can occur when local cerebral glucose utilization (LCGU) is decreased in some brain structures. Unilateral visual deprivation was induced by monocular enucleation in 25 rats. After 1 week, the contralateral structures of the visual system were analyzed for (1) densities of glucose transporters Glut1 and Glut3 (immunoautoradiography), (2) LCGU (2-[14C]deoxyglucose method) and (3) local rate constants (3-O[14C]methylglucose method). The ipsilateral structures served as controls. During chronic visual deprivation Glut1 and Glut3 densities, LCGU and rate constants were significantly decreased in some structures of the visual system and remained unchanged in others. These results indicate a moderate degree of downregulation of glucose transporters, LCGU and rate constants in the visual system during visual deprivation.