Induction of a NOTCH3 Lehman syndrome mutation in osteocytes causes osteopenia in male C57BL/6J mice

Lateral Meningocele or Lehman Syndrome (LMS) is associated with NOTCH3 mutations causing deletions of the PEST domain and a gain-of-NOTCH3 function. We demonstrated that Notch3em1Ecan mice harboring Notch3 mutations analogous to those found in LMS are osteopenic because of enhanced bone resorption. To determine the contribution of specific cell lineages to the phenotype, we created a conditional-by-inversion (Notch3COIN) model termed Notch3em2Ecan in which Cre recombination generates a Notch3INV allele expressing a NOTCH3 mutant lacking the PEST domain. Germ line Notch3COIN inversion caused osteopenia and phenocopied the Notch3em1Ecan mutant, validating the model. To induce the mutation in osteocytes, smooth muscle and endothelial cells, Notch3COIN mice were bred with mice expressing Cre from the Dmp1, Sm22a and Cdh5 promoters, respectively, creating experimental mice harboring Notch3INV alleles in Cre-expressing cells and control littermates harboring Notch3COIN alleles. Notch3COIN inversion in osteocytes led to femoral and vertebral cancellous bone osteopenia, whereas Notch3COIN inversion in mural Sm22a or endothelial Cdh5-expressing cells did not result in a skeletal phenotype. In conclusion, introduction of the LMS mutation in osteocytes but not in vascular cells causes osteopenia and phenocopies Notch3em1Ecan global mutant mice.

Role of nuclear factor of activated T cells in chondrogenesis osteogenesis and osteochondroma formation

PURPOSE

Nuclear factor of activated T cells (NFATc) are transcription factors that play a function in the immune response and in osteoclast differentiation. In the present work, we define the function of NFATc2 in chondrogenic and osteogenic cells.

METHODS

Nfatc2^loxP/loxP and Nfatc1^loxP/loxP;Nfatc2^loxP/loxP conditional mice were crossed with Prx1-Cre transgenics to inactivate Nfatc2 singly and with Nfatc1. Femurs and vertebrae were examined by microcomputed tomography (µCT) X-Ray images and histology and analyzed for the presence of osteochondromas.

RESULTS

µCT demonstrated that Prx1-Cre;Nfatc2^∆/∆ female mice had transient osteopenia and male mice did not have a cancellous or a cortical bone phenotype when compared to control mice. In contrast, the dual inactivation of Nfatc1 and Nfatc2 in Prx1-expressing cells resulted in cancellous osteopenia and small bones at 1 month of age in both sexes. Nfatc1;Nfatc2 deleted mice exhibited a ~ 50% decrease in bone volume and connectivity. Total bone area, periosteal and endocortical bone perimeters and femoral length were reduced indicating smaller bones. As the mice matured, the shortening of the femoral length persisted, but the osteopenic phenotype resolved and cancellous femoral bone of 4-month-old Nfatc1;Nfatc2 deleted mice was not different from controls although male mice had vertebral osteopenia. In addition, Nfatc1;Nfatc2 deleted mice displayed distortion of the distal metaphysis and, as they matured, the articular presence of mineralized tumors with the appearance of osteochondromas.

CONCLUSION

Our studies reveal that NFATc1 and NFATc2 are necessary for optimal bone homeostasis and the suppression of osteochondroma formation.

Comparative transcriptome analysis of inner blood-retinal barrier and blood-brain barrier in rats

Although retinal microvessels (RMVs) and brain microvessels (BMVs) are closely related in their developmental and share similar blood-neural barriers, studies have reported markedly different responses to stressors such as diabetes. Therefore, we hypothesized that RMVs and BMVs will display substantial differences in gene expression levels even though they are of the same embryological origin. In this study, both RMVs and BMVs were mechanically isolated from rats. Full retinal and brain tissue samples (RT, BT) were collected for comparisons. Total RNA extracted from these four groups were processed on Affymetrix rat 2.0 microarray Chips. The transcriptional profiles of these tissues were then analyzed. In the present paper we looked at differentially expressed genes (DEGs) in RMVs (against RT) and BMVs (against BT) using a rather conservative threshold value of ≥  ± twofold change and a false discovery rate corrected for multiple comparisons (p < 0.05). In RMVs a total of 1559 DEGs were found, of which 1004 genes were higher expressed in RMVs than in RT. Moreover, 4244 DEGs between BMVs and BT were identified, of which 1956 genes were ≥ twofold enriched in BMVs. Using these DEGs, we comprehensively analyzed the actual expression levels and highlighted their involvement in critical functional structures in RMVs and BMVs, such as junctional complex, transporters and signaling pathways. Our work provides for the first time the transcriptional profiles of rat RMVs and BMVs. These results may help to understand why retina and brain microvasculature show different susceptibilities to stressors, and they might even provide new insight for pharmacological interventions.

[The use of sunglasses during leisure time and work : Lack of prevention of sun-induced eye damage]

OBJECTIVE

This study aimed at collecting representative national data on the use of sunglasses on sunny summer days during leisure time or work as well as identifying population and professional groups with a pronounced lack of preventive measures to avoid sun-induced eye damage.

MATERIAL AND METHODS

Within the representative National Cancer Aid Monitoring, data on the use of sunglasses during leisure time was assessed among 3000 individuals aged 14-45 years in 2015, as well as on the use during outdoor work among 485 workers aged 14-45 years in 2016. Associations between the use of sunglasses and sociodemographic characteristics were assessed with the χ²-test. Additionally, descriptive and bivariate methods were used to assess connections between the use of sunglasses at work and each professional group.

RESULTS

While more than half of the general population normally or often wear sunglasses on a sunny summer day, only one third of outdoor workers do so. While approximately every seventh individual surveyed never wears sunglasses during leisure time, among outdoor workers it is one out of three. The use during leisure time increases with age.

DISCUSSION

Use of sunglasses during work could be supported by targeted information on UV-induced eye damage by ophthalmologists and company physicians with additional support from accident insurances and employers. Concerning preventive measures occupational groups such as landscapers, farmers and bricklayers who are strongly exposed to sunlight but rarely wear sunglasses are important groups.

Der aktuelle Stellenwert von PUVA- und UVA-1-Therapie als sichere und wirksame Therapieoptionen bei zahlreichen Hautkrankheiten

Sonnenlicht wurde von vielen Kulturvölkern schon vor langer Zeit zu gesundheitlichen Zwecken genutzt. Schon damals wurden photosensibilisierende Pflanzenbestandteile topisch oder systemisch angewendet, bevor die Haut dem Sonnenlicht ausgesetzt wurde. Nach Jahrzehnten der erfolgreichen Anwendung haben sich PUVA- und UVA-1-Phototherapie heute als sichere und effektive Standardoptionen zur Behandlung zahlreicher Dermatosen etabliert, wobei die UVA-1-Therapie in der Regel nur von spezialisierten Zentren angeboten wird. Unter Berücksichtigung internationaler Empfehlungen soll zur Minimierung des Langzeitrisikos die Anzahl der PUVA-Behandlungen in der Regel 200 – 250 nicht übersteigen. Bei einer Überschreitung dieser Zahl ist die Indikation für weitere PUVA-Behandlungen besonders kritisch abzuwägen. Daneben sind dann auch engmaschige Hautkrebsvorsorgeuntersuchungen erforderlich. Um eine noch bessere Risiko-Nutzen-Abwägung sowie Anwendungssicherheit für die Patienten zu gewährleisten, bedarf es weiterer Langzeit-Ergebnisse.

Reproductive activity triggers accelerated male mortality and decreases lifespan: genetic and gene expression determinants in Drosophila

Reproduction and aging evolved to be intimately associated. Experimental selection for early-life reproduction drives the evolution of decreased longevity in Drosophila whereas experimental selection for increased longevity leads to changes in reproduction. Although life history theory offers hypotheses to explain these relationships, the genetic architecture and molecular mechanisms underlying reproduction-longevity associations remain a matter of debate. Here we show that mating triggers accelerated mortality in males and identify hundreds of genes that are modulated upon mating in the fruit fly Drosophila melanogaster. Interrogation of genome-wide gene expression in virgin and recently mated males revealed coherent responses, with biological processes that are upregulated (testis-specific gene expression) or downregulated (metabolism and mitochondria-related functions) upon mating. Furthermore, using a panel of genotypes from the Drosophila Synthetic Population Resource (DSPR) as a source of naturally occurring genetic perturbation, we uncover abundant variation in longevity and reproduction-induced mortality among genotypes. Genotypes displayed more than fourfold variation in longevity and reproduction-induced mortality that can be traced to variation in specific segments of the genome. The data reveal individual variation in sensitivity to reproduction and physiological processes that are enhanced and suppressed upon mating. These results raise the prospect that variation in longevity and age-related traits could be traced to processes that coordinate germline and somatic function.

Quality of life in thalassemia: a comparison of SF-36 results from the thalassemia longitudinal cohort to reported literature and the US norms

Thalassemia is a chronic, inherited blood disorder, which, in its most severe form, causes life-threatening anemia. Advances in treatment have led to increased life expectancy however the need for chronic blood transfusions and chelation therapy remains a significant burden for patients. Our study compared health related quality of life (HRQOL) from the Thalassemia Clinical Research Network's (TCRNs) Thalassemia Longitudinal Cohort (TLC) study to US norms and assessed association with clinical variables. There were 264 patients over age 14 who completed the Medical Outcomes Study 36-Item Short Form Health Survey version 2 (SF36v2) baseline assessment. When compared to US norms, TLC patients had statistically significant (P < 0.05) worse HRQOL on five of the eight subscales (physical functioning, role-physical, general health, social functioning, and role-emotional) and on both summary scales (physical component summary and mental component summary). Women, older patients, and those with more disease complications and side effects from chelation reported lower HRQOL. In general, adolescents and adults with thalassemia report worse HRQOL than the US population, despite contemporary therapy. The SF-36 should become a standard instrument for assessing HRQOL in thalassemia to determine predictors of low HRQOL which may be better addressed by a multidisciplinary team.

[Current concepts for experimental micro-CT in small animals]

The number of publications describing the use of micro-computed tomography (microCT) for preclinical in vivo imaging of small animals has risen considerably within the last few years. The purpose of this review is to familiarize the reader with the basic principles of microCT, to present successful experimental approaches in order of the evaluated organ system, and to highlight limitations that need to be considered when planning microCT-based studies.

Regular-to-chaotic tunneling rates using a fictitious integrable system

We derive a formula predicting dynamical tunneling rates from regular states to the chaotic sea in systems with a mixed phase space. Our approach is based on the introduction of a fictitious integrable system that resembles the regular dynamics within the island. For the standard map and other kicked systems we find agreement with numerical results for all regular states in a regime where resonance-assisted tunneling is not relevant.

Cochrane Skin Group systematic reviews are more methodologically rigorous than other systematic reviews in dermatology

BACKGROUND

The Cochrane collaboration aims to produce high-quality systematic reviews. It is not known whether the methods used in producing Cochrane Skin Group (CSG) reviews result in higher quality reviews than other systematic reviews in dermatology.

OBJECTIVES

To determine how the methodological quality of dermatological CSG reviews published in The Cochrane Library and in peer-reviewed journals compare with non-Cochrane systematic reviews.

METHODS

Two blinded investigators independently assessed review quality using the 10-item Oxman and Guyatt scale.

RESULTS

Thirty-eight systematic reviews (17 Cochrane reviews published in The Cochrane Library, 11 Cochrane reviews published in peer-reviewed journals and 10 non-Cochrane reviews published in peer-reviewed journals) were examined. The Cochrane Library reviews included quality of life (11/17 vs. 1/10, P = 0.014) and adverse outcomes (14/17 vs. 2/10, P = 0.003) more often than non-Cochrane reviews published in peer-reviewed journals. Cochrane reviews published in both peer-reviewed journals and The Cochrane Library were more likely to include comprehensive search strategies (11/11 and 17/17 vs. 6/10, P-values = 0.04 and 0.01), take steps to minimize selection bias (11/11 and 16/17 vs. 3/10, P-values = 0.003 and 0.001) and appropriately assess the validity of all included trials (10/11 and 16/17 vs. 4/10, P-values = 0.04 and 0.007) than non-Cochrane reviews. Overall, Cochrane reviews published both in peer-reviewed journals and in The Cochrane Library were assigned higher quality scores by reviewers than non-Cochrane reviews (median = 6.0 and 6.5 vs. 4.5, P-values = 0.01 and 0.002).

CONCLUSIONS

The Cochrane Library systematic review methodology leads to higher quality reviews on dermatological topics.

Statins and fibrates for preventing melanoma

BACKGROUND

Effective treatment for advanced melanoma is lacking. While no drug therapy currently exists for prevention of melanoma, in vitro, case-control, and animal model evidence suggest that lipid-lowering medications, commonly taken for high cholesterol, might prevent melanoma.

OBJECTIVES

To assess the effects of statin or fibrate lipid-lowering medications on melanoma outcomes.

SEARCH STRATEGY

We searched the Cochrane Skin Group Specialised Register (February 2003), CENTRAL (The Cochrane Library Issue 1, 2005), MEDLINE (to March 2003), EMBASE (to September 2003), CANCERLIT (to October 2002), Web of Science (to May 2003), and reference lists of articles. We approached study investigators and pharmaceutical companies for additional information (published or unpublished studies).

SELECTION CRITERIA

Trials involving random allocation of study participants, where experimental groups used statins or fibrates and participants were enrolled for at least four years of therapy.

DATA COLLECTION AND ANALYSIS

Three authors screened 109 abstracts of articles with titles of possible relevance. We then thoroughly examined the full text of 72 potentially relevant articles. We requested unpublished melanoma outcomes data from the corresponding author of each qualifying trial.

MAIN RESULTS

We identified 16 qualifying randomised controlled trials (RCTs) (seven statin, nine fibrate). Thirteen of these trials (involving 62,197 participants) provided data on incident melanomas (six statin, seven fibrate). A total of 66 melanomas were reported in groups receiving the experimental drug and 86 in groups receiving placebo or other control therapies. For statin trials this translated to an odds ratio of 0.90 (95% confidence interval 0.56 to 1.44) and for fibrate trials an odds ratio of 0.58 (95% confidence interval 0.19 to 1.82). Subgroup analyses failed to show statistically significant differences in melanoma outcomes by gender, melanoma occurrence after two years of participation in trial, stage or histology, or trial funding. Subgroup analysis by type of fibrate or statin also failed to show statistically significant differences, except for the statin subgroup analysis which showed reduced melanoma incidence for lovastatin, based on one trial only (odds ratio 0.52, 95% confidence interval 0.27 to 0.99).

AUTHORS' CONCLUSIONS

The melanoma outcomes data collected in this review of RCTs of statins and fibrates does not exclude the possibility that these drugs prevent melanoma. There was a 10% and 42% reduction for participants on statins and fibrates, respectively, however these results were not statistically significant. Until further evidence is established, limiting exposure to ultraviolet radiation remains the most effective way to reduce the risk of melanoma.

Circadian periodicity of cerebral blood flow revealed by laser-Doppler flowmetry in awake rats: relation to blood pressure and activity

Cardiovascular parameters such as arterial blood pressure (ABP) and heart rate display pronounced circadian variation. The present study was performed to detect whether there is a circadian periodicity in the regulation of cerebral perfusion. Normotensive Sprague-Dawley rats (SDR, approximately 15 wk old) and hypertensive (mREN2)27 transgenic rats (TGR, approximately 12 wk old) were instrumented in the abdominal aorta with a blood pressure sensor coupled to a telemetry system for continuous recording of ABP, heart rate, and locomotor activity. After 5-12 days, a laser-Doppler flow (LDF) probe was attached to the skull by means of a guiding device to measure changes in brain cortical blood flow (CBF). After the animals recovered from anesthesia, measurements were taken for 3-4 days. The time series were analyzed with respect to the midline estimating statistic of rhythm (i.e., mean value of a periodic event after fit to a cosine function), amplitude, and acrophase (i.e., phase angle that corresponds to the peak of a given period) of the 24-h period. The LDF signal displayed a significant circadian rhythm, with the peak occurring at around midnight in SDR and TGR, despite inverse periodicity of ABP in TGR. This finding suggests independence of LDF periodicity from ABP regulation. Furthermore, the acrophase of the LDF was consistently found before the acrophase of the activity. From the present data, it is concluded that there is a circadian periodicity in the regulation of cerebral perfusion that is independent of circadian changes in ABP and probably is also independent of locomotor activity. The presence of a circadian periodicity in CBF may have implications for the occurrence of diurnal alterations in cerebrovascular events in humans.

Experimental approaches to evaluate endothelin-A receptor antagonists

A large body of evidence suggests a substantial role of the endothelin (ET) system in the pathophysiology of a variety of disease states, mainly of the cardiovascular system. Recently bosentan, an ET receptor antagonist, has received approval by the Food and Drug Administration (FDA) for use in pulmonary artery hypertension. The ET system may also be involved in cerebrovascular disorders such as stroke and, most notably, development of cerebral vasospasm following subarachnoid hemorrhage. The pathophysiological mechanisms contributing to the development of a cerebral vasospasm after subarachnoid hemorrhage may be taken as a paradigm to explore mechanisms leading to secondary ischemic brain damages in a variety of insults such as stroke and trauma. The present review provides the evidence to evaluate ET receptor antagonists for potential prophylactic and therapeutic use in patients suffering from subarachnoid hemorrhage. The rationale to develop selective ETA receptor antagonists is given with respect to basic and applied studies. This may be useful to better define the desired profile of action of a given compound, and it may also help to design appropriate preclinical and clinical trials, most desirably in close cooperation with pharmaceutical companies and neurosurgical departments.

Growth/differentiation factor-15 (GDF-15), a novel member of the TGF-beta superfamily, promotes survival of lesioned mesencephalic dopaminergic neurons in vitro and in vivo and is induced in neurons following cortical lesioning

This review summarizes the evidence that GDF-15, a recently discovered member of the TGF-beta superfamily, is a trophic factor for nigral dopamine neurons, both in vitro and in vivo. Specifically, GDF-15 promotes survival and differentiation of embryonic rat dopaminergic neurons, but not of other neuron populations, with the exception of serotonergic raphe neurons. The neurotrophic effect of GDF-15 seems to be direct and not mediated through glial cells. In the rat 6-hydroxydopamine model of parkinsonism GDF-15 rescues intoxicated dopaminergic neurons and abolishes abnormal turning behavior. The most prominent site of synthesis of GDF-15 within the brain is the choroid plexus, which secretes GDF-15 into the cerebrospinal fluid, from where the molecule can penetrate through the ependymal layer into the parenchyma. Analysis of mouse mutants lacking GDF-15 will reveal whether the endogenous factor also has a role in promoting embryonic and protecting lesioned nigral dopamine neurons.

Expression of growth differentiation factor-15/ macrophage inhibitory cytokine-1 (GDF-15/MIC-1) in the perinatal, adult, and injured rat brain

We and others have recently cloned a new member of the transforming growth factor-beta superfamily, growth differentiation factor-15/ macrophage inhibitory cytokine-1 (GDF-15/MIC-1). Using in situ hybridization and immunohistochemistry, we determined the distribution of GDF-15/MIC-1 mRNA and protein in the perinatal and cryolesioned adult rat brain. The choroid plexus epithelium of all ventricles represents the site of strongest and almost exclusive mRNA expression in the normal perinatal and adult brain. The newborn rat brain reveals GDF-15/MIC-1 immunoreactivity (ir) in ependymal cells lining the ventricles, in the striatal subventricular zone, and in populations of nonneural cells of the thalamic/hippocampal lamina affixa, in addition to that in the choroid plexus. Unilateral cryogenic cortical lesioning induced a significant increase of GDF-15/MIC-1 mRNA expression and ir at the lesion site and expression in presumed neurons within the dorsal thalamic area. At the lesion site, GDF-15/MIC-1-producing cells showed immuncytochemical features of neurons, macrophages, and activated microglial cells. Fluorescent microscopy revealed both intra- and extracellular GDF-15/MIC-1 ir. Up-regulation of GDF-15/MIC-1 in activated macrophages (Mstraight phi) is also supported by RT-PCR, ICC, and Western blot experiments showing pronounced induction of GDF-15/MIC-1 expression (mRNA and protein) in retinoic acid/phorbol ester-stimulated human M phi. Our data suggest that 1) GDF-15/MIC-1 is secreted into the cerebrospinal fluid and 2) in the newborn brain may penetrate through the ependymal lining and act on developing neurons and/or glial cells. As a constituent of cells in the lamina affixa, the protein might be involved in the regulation of mesenchyme-epithelial interactions. Finally, GDF-15/MIC-1 may also act within the antiinflammatory cytokine network activated in CNS lesions.

Xenon-induced flow activation in patients with cerebral insult who undergo xenon-enhanced CT blood flow studies

BACKGROUND AND PURPOSE

Stable xenon-enhanced CT ((s)Xe/CT) has gained wide acceptance in the assessment of regional cerebral blood flow (rCBF) in patients with intracranial abnormalities. The aim of this study was to test whether the contrast medium (ie, (s)Xe) itself directly induces relevant changes in rCBF, thereby distorting any valid determination of cerebral perfusion by using (s)Xe/CT.

METHODS

To characterize the degree and temporal dynamics of (s)Xe-induced flow activation, a thermal diffusion (TD)-based microprobe was placed subcortically into the frontal lobe on either hemisphere to assess rCBF (TD-rCBF) continuously in 23 patients (mean age, 55 +/- 18 years) with severe intracranial insult who were undergoing (s)Xe/CT.

RESULTS

In 35, the (s)Xe/CT studies TD-rCBF rose from 25 +/- 17 mL/100 g per minute (range, 5-42 mL/100 g per minute) before (s)Xe administration to 28 +/- 21 mL/100 g per minute (range, 6-46 mL/100 g per minute) after arterial (s)Xe saturation was reached. Analysis of the flow activation curve showed a logarithmic shape with an increase in TD-rCBF between 3% and 7% within the first 76 seconds of (s)Xe wash-in (12% after 190 seconds) and showed no further augmentation until the end of the blood flow study.

CONCLUSION

The observed (s)Xe-induced rCBF activation, which showed significant inter- and intraindividual variability, might lead to overestimation of rCBF in patients with severe intracranial insult. The obtained flow activation curve provides essential information that may allow subsequent refinement of the methodology, aiming to further minimize the influence of (s)Xe-induced rCBF activation on rCBF calculations when using (s)Xe/CT technology.

Time course of apoptotic cell death after experimental neurotrauma

Traumatic or ischemic brain injury may give rise to the development of secondary brain damage. In the present study the time course of TUNEL staining which is widely used to delineate apoptotic reaction pattern was followed after experimental neurotrauma in order to test the hypothesis that apoptotic cell death may be involved in the development of secondary brain damage. Neurotrauma was induced in male Wistar rats by applying a cold probe to the exposed dura over the temporo-parietal cortex. Animals were sacrificed between 1 and 72 hours after trauma and coronal sections prepared from the lesioned area and adjacent tissue. The TUNEL staining was employed to detect DNA-fragmentation and conventional HE staining of sequential slices to delineate the extent of the lesion. Occurrence of positively stained cells was detected by a computer-based quantification system and stored on hard disk. TUNEL-positive nuclei were observed as early as one hour after lesion and peaked at 3 hours. There after, the number of cells detected decreased steadily. Histological examination revealed two different types of morphology in TUNEL-positive cells. A small proportion termed type I-cells displayed additional signs of apoptotic cell death such as nuclear condensation and fragmentation while type-II were considered to undergo necrotic cell death. Thus, TUNEL staining proved to be an unspecific marker of apoptotic cell death in the present study. Nevertheless, the data suggest that apoptotic cell death does not contribute substantially to the final extent of cold induced brain tissue damage.

Specific pattern of growth factor distribution in chronic subdural hematoma (CSH): evidence for an angiogenic disease

BACKGROUND

The aim of this prospective study was to evaluate the significance of growth factors as determinants of the pathological degree of neovascularisation found in the parietal neomembrane of chronic subdural hematoma (CSH). Thus far the pathogenesis of the vascularisation has not been elucidated.

METHOD

The concentrations of growth factors, i.e. vascular endothelial derived growth factor (VEGF), basic fibroblast growth factor (bFGF) and platelet derived growth factor (PDGF) were determined using ELISA technique in hematoma fluid and serum of 20 patients with uni- or bilateral CSH. For comparison, growth factor concentrations were determined in cerebrospinal fluid (CSF) of patients undergoing diagnostic myelography.

FINDINGS

Concentrations of VEGF and bFGF were significantly (p < 0.001) increased in the hematoma fluid as compared with serum (VEGFh = 8.142 pg/ml, bFGFh = 8.7 pg/ml versus VEGFS = 368 pg/ml, bFGF, = 1.8 pg/ml). In contrast, PDGF concentration was significantly (p < 0.001) lower in the hematoma (PDGFh = 3,456 pg/ml versus PDGF, = 31,937 pg/ml). The serum levels for VEGF, bFGF and PDGF in CSH patients lay within the range of normal volunteers. No growth factors were found in normal CSF.

INTERPRETATION

These results reveal a specific distribution pattern of growth factors in CSH patients. This pattern suggests that CSH may be considered a member of the angiogenic disease family.

Day-night variation in the in vitro contractility of aorta and mesenteric and renal arteries in transgenic hypertensive rats

TGR(mREN2)27 (TGR) rats develop severe hypertension and an inverted circadian blood pressure profile with peak blood pressure in the day-time rest phase. The present study investigated the in vitro responsiveness of different arteries of TGR rats during day and night. Twelve-week-old TGR rats and normotensive Sprague-Dawley (SPRD) controls, synchronized to 12h light, 12h dark (LD 12:12) (light 07:00-19:00), were killed at 09:00 (during rest) and 21:00 (during activity), and endothelium-dependent relaxation by acetylcholine and vascular contraction by angiotensin II were studied by measuring isometric force in ring segments of abdominal aorta and mesenteric and renal arteries. In SPRD rats, consistent day-night variation was found, with greater responses to angiotensin II during the daytime rest span. In TGR rats, biological time-dependent differences were found in the renal vasculature, but not in the aorta and mesenteric artery. Relaxation of SPRD rat aorta and mesenteric artery by acetylcholine was greater at 09:00, whereas in TGR rats, day-night variation was absent (mesenteric artery) or inverted (aorta). In conclusion, based on the study of two time points, day-night variation in vascular contractility of aorta and mesenteric artery is blunted in TGR rats, whereas renal artery segments showed an unchanged day-night pattern compared to SPRD controls.

Bedside monitoring of cerebral blood flow by transcranial thermo-dye-dilution technique in patients suffering from severe traumatic brain injury or subarachnoid hemorrhage

Bedside measurement of cerebral blood flow (CBF) represents an important feature in monitoring of neurointensive care patients which is hard to establish. Therefore, we adopted a recently described thermo-dye-dilution-based approach for monitoring CBF in patients suffering from severe cerebral insults, that is, traumatic brain injury (TBI) or subarachnoid hemorrhage (SAH). Combined fiberoptic-thermistor catheters were placed in one jugular venous bulb and in the abdominal aorta of 16 patients. Following central venous injection of a 50-mL bolus of precooled indocyanine green (ICG) solution, CBF was determined as a function of the mean transit times of coldness and dye. In addition, measurements of CBF using stable xenon-enhanced computerized tomography (sXe-CT) were simultaneously performed in 10 patients. A total of 272 thermo-dye-dilution measurements yielded 196 valid results, with CBF ranging from 26.2 to 144.8 mL 100 g(-1) min(-1). Reproducibility was fairly good, with the standard deviation within sets of repeated measurements being 6.3 mL 100 g(-1) min(-1) and 9.4 as the mean coefficient of variation. Simultaneously obtained values with sXe-CT displayed a good correlation (r = 0.843, p < 0.01); however, the thermo-dye-dilution method consistently overestimated CBF. Data analysis using the Bland and Altman methodology revealed a large bias of 45.7 mL 100 g(-1) min(-1) with a +/- 2 SD range of 37 mL 100 g(-1) min(-1), indicating a rather poor agreement. The thermo-dye-dilution method proved a reasonably reproducible technique, enabling repeated long-term bedside measurements of CBF in neurointensive care patients with a minimum of time effort. However, a high failure rate was also noted, and consistent overestimation of perfusion was observed in comparison to sXe-CT measurements. Although the thermo-dye-dilution technique has been successfully validated in patients with normal neurovascular function, its applicability for bedside monitoring of CBF appears uncertain in patients suffering from severe TBI or SAH.

Effect of moderate hypothermia on experimental severe subarachnoid hemorrhage, as evaluated by apparent diffusion coefficient changes

OBJECTIVE

The aims of this study were to investigate the early changes in the mean apparent diffusion coefficient (ADC) after severe subarachnoid hemorrhage (SAH), as a marker of ischemic damage, and to examine the effects of moderate hypothermia, induced at various time points, on ADC changes.

METHODS

ADC maps were calculated from diffusion-weighted, blipped-epi, spin echo, magnetic resonance imaging sequences (2.35-T BIOSPEC 24/40 scanner; Bruker Medizin Technik GmbH, Karlsruhe, Germany) for 21 anesthetized (0.45-1% halothane, temperature-adjusted/30% oxygen/69% nitrogen) and ventilated Wistar rats. After baseline scanning, bolus injection of 0.5 ml of autologous arterial blood or artificial cerebrospinal fluid (control group), into the cisterna magna, was performed. Serial scanning was performed for 3 hours after injection, using normothermic or hypothermic (32 degrees C) rats. In an additional series of experiments, hypothermia was initiated either immediately or 60 minutes after normothermic SAH. The water contents of the removed brains were calculated using the wet/dry weight method.

RESULTS

The ADC values did not change in the control group but decreased to 88.6+/-5.2% (P < 0.05 versus baseline) after SAH and remained significantly decreased throughout the experiment in normothermia. An injection of blood during hypothermia caused an initial decrease in ADC to 96.1+/-5.6% (P < 0.05 versus baseline); values continuously increased and reached normal levels within 60 minutes. Delayed hypothermia also normalized ADC values within the observation period. The brain water content in the control group was 80.3+/-0.1%, that after SAH in normothermia was 81.1+/-0.7%, and that after SAH in hypothermia was 79.3+/-0.5%.

CONCLUSION

This model of severe SAH in rats causes significant ADC changes, which are reversible by application of moderate hypothermia even when it is induced after a 60-minute delay. These findings support the concept of moderate hypothermia exerting a neuroprotective effect in severe SAH.

Improvement of renal dysfunction in rats with chronic heart failure after myocardial infarction by treatment with the endothelin A receptor antagonist, LU 135252

OBJECTIVE

To investigate the role of an activated endothelin system in the renal dysfunction observed in chronic heart failure after myocardial infarction.

METHODS

In rats with heart failure after myocardial infarction and in sham-operated animals (Sham), we investigated the effect on renal function of long-term oral treatment with the selective endothelin A (ETA) receptor antagonist, LU 135252 (30 mg/kg per day; groups MI/LU and Sham/LU) or placebo (groups MI/P, Sham/P). Only animals with extensive myocardial infarction (at least 46% of the left ventricle) were included in the study. Infarct size was matched between groups MI/P and MI/LU. Endogenous creatinine clearance, fractional sodium excretion, and plasma and urinary concentrations of endothelin were determined 12 weeks after myocardial infarction.

RESULTS

Endogenous creatinine clearance was significantly lower in group MI/P than in group Sham/P (MI/P: 0.64 +/- 0.05, Sham/P: 0.81 +/- 0.04 ml/min per 100 g body weight; P= 0.01 (means +/- SEM)). Treatment with LU 135252 completely prevented the decline in creatinine clearance in rats with chronic myocardial infarction (MI/LU: 0.98 +/- 0.21; Sham/LU: 0.83 +/- 0.10). Fractional sodium and protein excretion did not differ among the four groups. Group MI/P had a marked increase in plasma endothelin concentrations, which was not affected by treatment with LU 135252. Urinary endothelin excretion was significantly lower in group MI/P than in group Sham/P. In the treatment groups, no difference could be observed between animals that had suffered myocardial infarction and the sham-operated group, although LU 135252 markedly increased the urinary excretion of endothelin.

CONCLUSION

Our data demonstrate a restoration of impaired renal function in chronic ischaemic heart failure by treatment with the selective ETA receptor antagonist, LU 135252. These results offer a promising therapeutic option for the treatment of renal insufficiency in patients with chronic heart failure.

Targeting angiogenesis inhibits tumor infiltration and expression of the pro-invasive protein SPARC

The solid growth of high-grade glioma appears to be critically dependent on tumor angiogenesis. It remains unknown, however, whether the diffuse infiltration of glioma cells into healthy adjacent tissue is also dependent on the formation of new tumor vessels. Here, we analyze the relationship between tumor angiogenesis and tumor cell infiltration in an experimental glioma model. C6 cells were implanted into the dorsal skinfold chamber of nude mice, and tumor angiogenesis was monitored by intravital fluorescence videomicroscopy. Glioma infiltration was assessed by the extent of tumor cell invasion into the adjacent chamber tissue and by expression of SPARC, a cellular marker of glioma invasiveness. To test the hypothesis that glioma angiogenesis and glioma infiltration are codependent, we assessed tumor infiltration in both the presence and the absence of the angiogenesis inhibitor SU5416. SU5416 is a selective inhibitor of the VEGF/Flk-1 signal-transduction pathway, a critical pathway implicated in angiogenesis. Control tumors demonstrated both high angiogenic activity and tumor cell invasion accompanied by strong expression of SPARC in invading tumor cells at the tumor-host tissue border. SU5416-treated tumors demonstrated reduced vascular density and vascular surface in the tumor periphery accompanied by marked inhibition of glioma invasion and decreased SPARC expression. A direct effect of SU5416 on glioma cell motility and invasiveness was excluded by in vitro migration and invasion assays. These results suggest a crucial role for glioma-induced angiogenesis as a prerequisite for diffuse tumor invasion and a possible therapeutic role for anti-angiogenic compounds as inhibitors of both solid and diffuse infiltrative tumor growth.

Continuous monitoring of regional cerebral blood flow: experimental and clinical validation of a novel thermal diffusion microprobe

OBJECT

Current clinical neuromonitoring techniques lack adequate surveillance of cerebral perfusion. In this article, a novel thermal diffusion (TD) microprobe is evaluated for the continuous and quantitative assessment of intraparenchymal regional cerebral blood flow (rCBF).

METHODS

To characterize the temporal resolution of this new technique, rCBF measured using the TD microprobe (TD-rCBF) was compared with rCBF levels measured by laser Doppler (LD) flowmetry during standardized variations of CBF in a sheep model. For validation of absolute values, the microprobe was implanted subcortically (20 mm below the level of dura) into 16 brain-injured patients, and TD-rCBF was compared with simultaneous rCBF measurements obtained using stable xenon-enhanced computerized tomography scanning (sXe-rCBF). The two techniques were compared using linear regression analysis as well as the Bland and Altman method. Stable TD-rCBF measurements could be obtained throughout all 3- to 5-hour sheep experiments. During hypercapnia, TD-rCBF increased from 49.3+/-15.8 ml/100 g/min (mean +/- standard deviation) to 119.6+/-47.3 ml/100 g/ min, whereas hypocapnia produced a decline in TD-rCBF from 51.2+/-12.8 ml/100 g/min to 39.3+/-5.6 m/100 g/min. Variations in mean arterial blood pressure revealed an intact autoregulation with pressure limits of approximately 65 mm Hg and approximately 170 mm Hg. After cardiac arrest TD-rCBF declined rapidly to 0 ml/100 g/min. The dynamics of changes in TD-rCBF corresponded well to the dynamics of the LD readings. A comparison of TD-rCBF and sXe-rCBF revealed a good correlation (r = 0.89; p < 0.0001) and a mean difference of 1.1+/-5.2 ml/100 g/min between the two techniques.

CONCLUSIONS

The novel TD microprobe provides a sensitive, continuous, and real-time assessment of intraparenchymal rCBF in absolute flow values that are in good agreement with sXe-rCBF measurements. This study provides the basis for the integration of TD-rCBF into multimodal monitoring of patients who are at risk for secondary brain injury.

Alternative/complementary medicine: wider usage than generally appreciated

OBJECTIVE

To test the hypothesis that there is substantial use of a practitioner of alternative/complementary medicine by patients traditionally considered to be underserved.

DESIGN

Cross-sectional, self-administered survey study.

SETTINGS

Three university hospital-affiliated general ambulatory clinics serving patients of different socioeconomic status and racial origin.

SUBJECTS

Five hundred and thirty-six (93% of those attending) consecutive clinic attendees.

OUTCOME MEASURES

Past use and desired future use of one or more practitioners of five modalities of alternative/complementary medicine and willingness to pay for these modalities out-of-pocket.

RESULTS

Past usage and desired future usage of one or more practitioners of alternative/complementary medicine was comparable at the three clinic sites despite wide differences in socioeconomic status and willingness/ability to pay out-of-pocket for these services. Multivariable analyses revealed lower self-rated health status and female gender (both p < 0.006) but not income, race, age or education as independent, significant predictors of use of a practitioner of alternative/complementary medicine.

CONCLUSION

Usage of alternative/complementary medicine is not confined to any well-circumscribed socioeconomic group and is common in patients often considered to be underserved. Self-assessed lower health status is significantly and independently associated with use of a practitioner of alternative/complementary care.

Targeting angiogenesis inhibits tumor infiltration and expression of the pro-invasive protein SPARC

The solid growth of high-grade glioma appears to be critically dependent on tumor angiogenesis. It remains unknown, however, whether the diffuse infiltration of glioma cells into healthy adjacent tissue is also dependent on the formation of new tumor vessels. Here, we analyze the relationship between tumor angiogenesis and tumor cell infiltration in an experimental glioma model. C6 cells were implanted into the dorsal skinfold chamber of nude mice, and tumor angiogenesis was monitored by intravital fluorescence videomicroscopy. Glioma infiltration was assessed by the extent of tumor cell invasion into the adjacent chamber tissue and by expression of SPARC, a cellular marker of glioma invasiveness. To test the hypothesis that glioma angiogenesis and glioma infiltration are codependent, we assessed tumor infiltration in both the presence and the absence of the angiogenesis inhibitor SU5416. SU5416 is a selective inhibitor of the VEGF/Flk-1 signal-transduction pathway, a critical pathway implicated in angiogenesis. Control tumors demonstrated both high angiogenic activity and tumor cell invasion accompanied by strong expression of SPARC in invading tumor cells at the tumor-host tissue border. SU5416-treated tumors demonstrated reduced vascular density and vascular surface in the tumor periphery accompanied by marked inhibition of glioma invasion and decreased SPARC expression. A direct effect of SU5416 on glioma cell motility and invasiveness was excluded by in vitro migration and invasion assays. These results suggest a crucial role for glioma-induced angiogenesis as a prerequisite for diffuse tumor invasion and a possible therapeutic role for anti-angiogenic compounds as inhibitors of both solid and diffuse infiltrative tumor growth.

Differential glial and vascular expression of endothelins and their receptors in rat brain after neurotrauma

We characterized the time-course, intensity of expression and cellular origin of components of the endothelin (ET) system in the rat brain after a standardized neurotrauma (cryogenic lesion of the parietal cortex). ET mRNAs were expressed at sham level after neurotrauma, whereas immunoreactivity for ET-1 was enhanced in glia and endothelium of the lesioned hemisphere and both hippocampi. The number of ET-3 positive mononuclear cells in the lesion perimeter increased starting at 24h after injury. At 48h after neurotrauma, ET-receptor immunoreactivity was increased in astrocytes. In basilar artery endothelium, ETB-immunoreactivity was reduced at 48h to 72h recovering at 7 days whereas ETA-receptor and ET-peptide immunoreactivities were not altered. In summary, neurotrauma leads to a multicellular stimulation of endothelins in the brain along with a delayed selective loss of vascular ETB-receptors. These changes seem to be posttranscriptional and cell type specific. They favor vasoconstriction increasing the risk of late vasospasm and ischemia.

Measuring VEGF-Flk-1 activity and consequences of VEGF-Flk-1 targeting in vivo using intravital microscopy: clinical applications

Vascular endothelial growth factor (VEGF)-Flk-1/KDR tyrosine kinase signaling pathway plays a pivotal role in tumor angiogenesis. Targeting this angiogenic signaling pathway presents a promising alternative for the treatment of neoplasms. However, recent experimental and clinical studies have suggested that VEGF-Flk-1/KDR activity is unevenly distributed throughout the tumor microvasculature. To further evaluate this phenomenon, the regional differences in VEGF-Flk-1/KDR signaling activities in vivo were studied using intravital fluorescence videomicroscopy in an experimental murine brain tumor model. Regional VEGF-Flk-1/KDR was assessed using the small molecule inhibitor SU5416, which selectively inhibits the tyrosine kinase receptor Flk-1. C(6) glioblastoma cells were implanted into the dorsal skinfold chamber preparation of nude mice. The process of tumor vascularization was repeatedly assessed over 22 days. SU5416 treatment resulted in a significant reduction in tumor vascular density (p<0.05). Regional microvascular evaluation indicated that the magnitude of this antiangiogenic effect was pronounced in the more angiogenic and better vascularized peritumoral areas than in the intratumoral areas of the tumor microvasculature. These results demonstrate regional differences in Flk-1 activity in vivo that may have significant impact on the susceptibility of tumors to compounds that target VEGF-Flk-1/KDR. This finding should be considered in upcoming clinical trials targeting individual signal transduction systems in cancer patients.

Endothelium-dependent and -independent vasoreactivity of rat basilar artery in chronic heart failure

Alterations of vasoreactivity are a well-known phenomenon in chronic heart failure (CHF), and activation of the endogenous endothelin (ET) system is suspected to contribute significantly. Regional differences in alterations of vasoreactivity exist; however, nothing is known about cerebrovascular reactivity in CHF. This is of interest in view of increased stroke risk in CHF. Therefore, 12 weeks after coronary artery ligation to induce CHF in rats, studies of vasoreactivity of the isolated basilar artery (BA) were performed and compared with third-order branches (MA-A3) and the main trunk (MA) of the superior mesenteric artery. Some of the animals received long-term ET-receptor antagonism by 11 weeks of treatment with the selective ET(A)-receptor antagonist LU 135252 or the mixed ET(A)/ET(B)-receptor antagonist bosentan. In rats with CHF, endothelium-dependent relaxation by acetylcholine and A23187 as well as endothelium-independent relaxation by sodium nitroprusside (SNP) was largely unaffected in BA or MA. However, in MA-A3, potency of SNP was diminished without change of maximal effect. ET-1-induced contraction did not differ in arteries from CHF and control rats, either in placeboor ET-receptor antagonist-treated animals. In summary, there was essentially no change of vascular reactivity in similar sized arteries obtained from brain and mesentery. This is in contrast to results on arteries from a variety of vascular regions published previously, thus supporting the concept of organ- and probably time-related changes of vascular function in the development of CHF. The absence of significant alteration of cerebral vasoreactivity may be taken to indicate that changes in cerebral blood flow and increased incidence of ischemic stroke in patients with CHF are caused not by local alterations of vascular function.

Endothelin b receptor deficiency is associated with an increased rate of neuronal apoptosis in the dentate gyrus

The dentate gyrus retains neuronal proliferative potential throughout life. Using immature endothelin B receptor-deficient (sl/sl) rats, a rabbit model of pneumococcal meningitis and autopsy brains from humans who died from pneumococcal meningitis, we explored the role of endothelin B receptors in physiological and pathological neuronal apoptosis in the dentate gyrus. At postnatal days 3-4, the rate of apoptosis in the dentate gyrus was high in all rats, declining to low levels in wild-type rats (+/+) on days 14 and 22, but remaining high in both homozygous (sl/sl) and heterozygous (sl/+) endothelin B receptor-deficient rats. Increased apoptosis was not significantly compensated for by neuronal proliferation. Hippocampal neuronal cultures also exhibited genotype-dependent apoptosis with the highest rate in neurons from homozygous endothelin B receptor-deficient (sl/sl) rats. In rabbit and human pneumococcal meningitis, increased apoptosis in the dentate gyrus was associated with loss of neuronal endothelin B receptor immunoreactivity. In conclusion, endothelin B receptors appear to act as neuronal survival factors in the dentate gyrus in rodents and man, both during postnatal development and under pathological conditions.

Effects of 30% stable xenon on regional cerebral blood flow in patients with intracranial pathology

Regional cerebral blood flow was assessed continuously in 22 patients with severe intracranial pathology undergoing xenon-enhanced computed tomography by means of an intraparenchymal thermodiffusion based microprobe. Thirty-four blood flow studies were analysed revealing an overall xenon-induced flow activation from about 12%. Regional CBF rose from 25 +/- 17 ml/100 g/min (mean +/- sd; range: 5.2-41.8 ml/100 g/min) before xenon administration to 28 +/- 21 ml/100 g/min (p = 0.012; range: 6.5-46.4 ml/100 g/min) when "steady-state" during xenon "wash-in" was reached. Flow activation curve demonstrated a logarithmic shape with an increase in rCBF between 3% and 7% within the first 90 seconds of xenon "wash-in", 12% after 160 seconds, and showed no further augmentation until the end of the blood flow study after 310 seconds. It is concluded that xenon inhalation leads to flow augmentation in patients with cerebral insult, which does not exceed flow activation obtained in normal subjects. The impact of the results on xenon-enhanced computed tomography cerebral blood flow calculations remains to be established.

Mediators of cerebral edema

The blood-brain barrier (BBB) which is located in the continuous endothelial lining of cerebral blood vessels rigidly controls exchange of water soluble compounds under physiological conditions. Under pathological conditions such as trauma or ischemia, BBB permeability may increase thus allowing plasma constituents to escape into brain tissue. This "opening" of the BBB may, at least in part, be mediated by massive release of autacoids resulting in vasogenic brain edema. Five criteria have to be fulfilled by an individual autacoid to be considered a mediator candidate of cerebral edema: i) a permeability-enhancing action under physiological conditions, ii) a vasodilatory action, iii) the ability to induce vasogenic brain edema, iv) an increase of concentration in the tissue or interstitial fluid under pathological conditions, and v) a decrease of brain edema by specific interference with the release or action of a given autacoid. Among the mediator candidates considered, bradykinin is the only one to meet all criteria. Histamine, arachidonic acid and free radicals including nitric oxide may also be considered mediators of brain edema, but for each of these compounds evidence is less clear than for bradykinin. Although the concept of mediators inducing brain edema is well established by experimental studies, only a bradykinin receptor antagonist has so far gained entrance into clinical evaluation.

Characterization of the contractile and relaxant action of the endothelin-1 precursor, big endothelin-1, in the isolated rat basilar artery

The presence of functional endothelin converting enzyme (ECE) activity in basilar artery ring segments was investigated by measuring the contractile and relaxant effects of big endothelin (ET)-1. Under resting tension conditions cumulative application of big ET1-1 elicited a concentration-related contraction with the concentration-effect curve (CEC) shifted to the right against ET-1 by a factor of 31 and 29 in segments with the endothelium intact or mechanically removed, respectively. Preincubation with the ET(A) receptor antagonist, BQ123, induced an apparently parallel rightwards shift without affecting the maximum contraction. This shift was more pronounced for ET-1 than for big ET-1. With the putative ECE inhibitor phosphoramidon (10(-3) M) in the bath a small rightwards shift of the CEC for big ET-1 was observed in control segments and a more marked one in de-endothelialized segments. In segments precontracted with prostaglandin (PG) F(2alpha) big ET-1 induced a significant although transient relaxation whereas ET-1 did not. However, in the presence of BQ123 both ET-1 and big ET-1 elicited concentration-related relaxation with a significantly higher maximum effect obtained with big ET-1. The potency was 13 fold higher for ET-1, which is markedly less than that found for contraction. The results, therefore, suggest 1) the presence of functional ECE-activity in the rat basilar artery wall, and 2) differences in the functional ECE activity located in the endothelium and media.

Hypertonic saline solution for control of elevated intracranial pressure in patients with exhausted response to mannitol and barbiturates

Critically elevated intracranial pressure (ICP) represents the most important cause of morbidity and mortality in patients suffering from severe traumatic brain injury (TBI) and is a serious complication after subarachnoid hemorrhage (SAH). Thus new strategies for the control of ICP are required. Based on the evidence available hypertonic saline solution (HSS) may be a promising approach. It was therefore the aim of the present study to evaluate in a prospective manner the effects of HSS on ICP and cerebral perfusion pressure (CPP) in patients with therapy-resistant elevation of ICP. A total of 48 bolus infusions of HSS (7.5%, 2 ml kg-1 b.w.; infusion rate 20 ml min-1) were given intravenously (range 1-15 per patient) to 10 patients (age 41 +/- 6 years) with TBI and SAH. Only patients with ICP > 25 mmHg not responding to standard ICP-management protocol and plasma sodium (Na+) concentration < 150 mmol l-1 were included in the study. Within the first hour after HSS application, ICP decreased from 33 +/- 9 mmHg to 19 +/- 6 mmHg (p < 0.05) and further to 18 +/- 5 mmHg at the time of maximum effect (98 +/- 11 min post bolus). Decrease of ICP was accompanied by a rise of CPP from 68 +/- 11 mmHg to 79 +/- 11 mmHg (p < 0.05) after 1 h and further to 81 +/- 11 mmHg at the time of maximum effect. Plasma Na+ concentration was 141 +/- 6 mmol l-1 before and 143 +/- 5 mmol l-1 1 h after HSS bolus. Corresponding values for plasma osmolality were 302 +/- 11 and 308 +/- 12 mOsm l-1. When the ICP lowering effect was transient, subsequent HSS bolus was necessary 163 +/- 54 min after previous dosing. The present results indicate that repeated bolus application of HSS (7.5% NaCl, 2 ml kg-1 b.w.) is an effective measure to decrease ICP which is otherwise refractory to standard therapeutic approaches. Whether or not the therapy scheme is also suited as primary measure for the control of ICP remains to be established.

Regression of left ventricular hypertrophy after stentless versus conventional aortic valve replacement

The goal of this study was to analyze regression of left ventricular hypertrophy after randomization to conventional biological versus stentless aortic valve replacement. Stentless (Freestyle, Toronto, n = 106) or conventional biological aortic valves (Carpentier-Edwards, n = 74) were evaluated prospectively. Preoperatively there were no differences with regard to aortic valve pathology, left ventricular function, and pressure gradients between the two patient groups. The patient annulus index (13.55 vs. 13.46 mm; NS) measured intraoperatively was used as baseline for further comparison. Postoperatively, left ventricular mass index was 213+/-77 g/m2 (stentless) compared with 202+/-72 (conventional group) g/m2 (NS), whereas after 6 months it was 141+/-41 g/m2 in the stentless and 170+/-43 g/m2 in the conventional group (P<.05). Regression of left ventricular hypertrophy occurs in all patients after aortic valve replacement. Nevertheless, the use of stentless bioprostheses leads to a significant enhancement, which may result in a reduction of the cardiac risk profile for the patient.

Glioma cell migration is associated with glioma-induced angiogenesis in vivo

To simultaneously assess glioma cell invasion and glioma angiogenesis in vivo by non-invasive and quantitative means, DiI-labeled C6 glioma spheroids were implanted into the dorsal skinfold chamber preparation of nude mice (n = 6). Heat-inactivated spheroids served as controls to distinguish between active and passive cell spread. Using multi-fluorescent intravital videomicroscopy, glioma cell migration was analyzed on days 1-4, 6, and 10 and spheroid vascularization was analyzed on days 3, 6, and 10 after implantation. Additionally, C6 glioma spheroids were implanted into the chronic cranial window of nude mice as an orthotopic implantation site (n = 4). In the dorsal skinfold chamber, spheroids were vascularized within 10 days and revealed a tumor-specific microvasculature. In parallel, individual glioma cells detached from the spheroid edge and migrated centrifugally demonstrating an affinity to tumor and host vessels. Glioma cells demonstrated a heterogeneous pattern of their regional migratory activity (0.2-9.6 microm/h) which correlated well with regional glioma angiogenesis (r = 0.733). Using the cranial window, glioma cells spread similarly demonstrating an affinity to the perivascular space of pial/subpial vessels with preference to the arteriolar segments. Intravital fluorescence microscopy represents a versatile technique to assess the complex relationship between glioma-driven angiogenesis and glioma cell invasion.

Endothelin converting enzyme activity in primary rat astrocytes is modulated by endothelin B receptors

Astrocytes express endothelin-1 (ET-1), ET-3, and their receptors, ET(A) and ET(B). We report here that activated astrocytes in vivo also express endothelin converting enzyme-1 (ECE-1). Higher basal ET-1 concentrations in astrocyte media from ET(B)-deficient (sl/sl) versus wildtype (+/+) rats suggested that altered ECE activity may be related to the absence of ET(B) receptors. Quantification of ECE activity in membranes from sl/sl astrocytes yielded a 50% higher conversion compared to +/+ astrocytes, with indistinguishable ECE-1 mRNA and protein levels. Kinetic analysis of ECE activity revealed similar V(max) values in sl/sl and +/+ astrocytes. Enzyme activity was competitively inhibited by phosphoramidon with K(i) values of 0. 6 and 0.3 microM, respectively. The K(m) value of ECE was 0.5 microM in +/+ and 0.2 microM in sl/sl astrocytes. Two-dimensional focussing of astrocytic ECE-1 uncovered heterogeneity of charge and molecular weight. ECE-1 from sl/sl revealed a glycosylation pattern different from +/+ astrocytes. In conclusion, the ET(B) receptor may, via ECE-1 glycosylation, exert a negative feedback on ECE activity in the astrocytic endothelin system.

Endothelin B receptor-deficient rats as a subtraction model to study the cerebral endothelin system

Endothelins, due to their potent vasoactivity and mitogenicity, appear to play an important role in the brain, where all components of the endothelin system, peptides, receptors and converting enzyme, are expressed. To further elucidate the role of the cerebral endothelin system, astrocytes and cerebral vessels from sl/sl rats, devoid of functional endothelin B receptors, have been employed. Astrocytes from sl/sl rats display the following abnormalities as compared to wild-type (+/+) cells: (i) elevated basal extracellular endothelin-1 levels; (ii) exclusive presence of functional endothelin A receptors; (iii) increased extracellular endothelin-1 levels upon endothelin A receptor blockade; (iv) augmented basal endothelin-converting enzyme activity; (v) altered calcium response to endothelin-1. The basilar artery of sl/sl rats shows an enhanced constricting response to endothelin-1 and fails to dilate in response to endothelin-3, shifting the endothelin vasomotor balance to constriction. In conclusion, endothelin B receptors may be essential for restricting extracellular endothelin-1 levels in the brain, as well as for a balanced cerebral vasomotor action of endothelins.

Temporal profile of expression and cellular localization of inducible nitric oxide synthase, interleukin-1beta and interleukin converting enzyme after cryogenic lesion of the rat parietal cortex

We used in situ hybridization, RT PCR and immunohistochemistry to study the time course of expression and the cellular localization of inducible nitric oxide synthase (iNOS) and interleukin-1beta (IL-1beta) during the first 7 days after induction of a standardized cryogenic lesion on the right parietal cortex in male rats. Cryogenic lesion induced iNOS mRNA in the lesioned hemisphere after 6 to 72 h with a maximum (15+/-2 cells/mm2, n=4, p<0.01 vs. sham) at 24 h. Microglia, invading monocytes and granulocytes in and around the lesion expressed iNOS immunoreactivity starting at 12 h and peaking (29+/-10 cells/mm2, n=4, p<0.05 vs. sham) at 24 h after lesion. Induction of IL-1beta mRNA expression was immediate with a peak (9+/-1 cells/mm2, n=4, p<0.01 vs. sham) at 24 h after cryogenic lesion. The number of round cells with IL-1beta immunoreactivity around the lesion was maximal (8+/-2 cells/0.1 mm2, n=3, p<0.01 vs. sham) at 24 h. A weak astrocytic expression of IL-1beta-immunoreactivity was seen in sham animal brains. Astrocytic IL-1beta-expression was significantly increased in the lesion hemisphere and both hippocampi. Interleukin converting enzyme (ICE) was expressed in astrocytes and microglia around the lesion 6 h after injury. The number of ICE immunoreactive cells (8+/-2 cells/0. 1 mm2, n=3, p<0.05 vs. sham) peaked at 72 h after lesion. Neuronal expression of ICE and IL-1beta was seen in the lesion periphery 72 h and 7 days after injury. At this time, morphological features of apoptosis were evident in cells in the lesion periphery. The data indicate an early activation of microglia and monocyte invasion into the lesion hemisphere leading to multicellular expression of iNOS, ICE, and IL-1beta. These events may contribute to the expansion of neuronal damage after brain injury.