[18 F]-labeled positron emission tomography ligand for the histamine H4 receptor

We synthesized 5-[¹⁸ F]-fluoro-1H-indol-2-yl)(4-methyl-1-piperazinyl)methanone ([¹⁸ F]5) via a Suzuki approach starting from a protected pinacol borane precursor followed by acidic hydrolysis of the t-Boc protecting group. The non-optimized radiochemical yield was 5.7 ± 1.35%, radiochemical purity was over 99%, and molar activity was 100.7 ± 34.5 GBq/μmol (n = 3). [¹⁸ F]5 was stable in rat plasma for at least 4 h and was evaluated by μPET imaging and biodistribution using a unilateral quinolinic acid rat model of neuroinflammation. The time-activity curve showed that [¹⁸ F]5 entered the brain immediately after intravenous injection and then left it progressively with a very low level reached from 30 min after injection. The biodistribution study showed no difference in the accumulation of [¹⁸ F]5 between the lesioned and intact side of the brain and between control rats and animals pretreated with a saturating dose of JNJ-7777120 as a specific H4R antagonist. Hence, despite its in vitro nanomolar affinity for H4R, and its ability to cross the blood-brain barrier in rats, [¹⁸ F]5 does not appear suitable to image in vivo the receptor by PET.

[The Dutch Personality Inventory for DSM-5 (PID-5-NL): psychometric properties and clinical application]

BACKGROUND

The Dutch Personality Inventory for DSM-5 (PID-5-NL) is the APA recommended questionnaire to assess maladaptive personality traits as defined in the Alternative DSM-5 model of personality disorders.

AIM

To describe of the psychometric qualities of the PID-5-NL, present of normative data and apply the PID-5-NL in clinical practice.

METHOD

The PID-5-NL was administered in a sample of adults from the general population in Flanders (Belgium) and in a sample of patients with a personality disorder in mental health care in the Netherlands. Scores on the PID-5 of a patient with borderline personality disorder are illustrated in a case vignette.

RESULTS

Reliability and validity of the PID-5-NL were satisfactory to good, and comparable with results from international research on the PID-5. It was remarkable that in the current research group, patients scored as low as or even lower than the group from the general population on a number of trait facets.

CONCLUSION

The PID-5-NL questionnaire is a useful tool to gain insight in a straightforward way into a wide range of relevant personality traits for diagnosis and treatment planning; provisional reference groups for the clinical practice in regular mental health care are made available on the basis of this study. Further refinement of the reference groups and further research within patients with externalizing personality problems is recommended.

Design of selective COX-2 inhibitors in the (aza)indazole series. Chemistry, in vitro studies, radiochemistry and evaluations in rats of a [18F] PET tracer

A series of novel derivatives exhibiting high affinity and selectivity towards the COX-2 enzyme in the (aza) indazole series was developed. A short synthetic route involving a bromination/arylation sequence under microwave irradiation and direct C–H activation were established in the indazole and azaindazole series respectively. In vitro assays were conducted and structural modifications were carried out on these scaffolds to furnish compound 16 which exhibited effective COX-2 inhibitory activity, with IC₅₀ values of 0.409 µM and an excellent selectivity versus COX-1. Radiolabeling of this most potent derivative [¹⁸F]16 was achieved after boron ester release and the tracer was evaluated in vivo in a rat model of neuroinflammation. All chemistry, radiochemistry and biological experimental data are discussed.

Design, synthesis and biological evaluation of potent FAAH inhibitors

A new series of 3-carboxamido-5-aryl-isoxazoles was designed, synthesized and evaluated for their biological activity. Different pharmacomodulations have been explored and the lipophilicity of these compounds was assessed. Investigation of the in vitro biological activity led to the identification of 5 compounds as potent FAAH inhibitors, their good FAAH inhibition capacity is probably correlated with their suitable lipophilicity. Specifically, compound 25 showed similar inhibition potency against FAAH in comparison with URB597, one of the most potent FAAH inhibitor known to date.

Making Surgical Care Safer: A Survey on the Implementation of the Checklist by Belgian Surgeons

BACKGROUND

The operating theatre (OT) is a complex environment. The purpose of this survey was to evaluate the implementation of the surgical checklist (SC) at individual level by Belgian Surgeons.

METHODS

A Surgical Checklist Questionnaire (SCQ) related to the use of the SC by individual surgeons was attached to the registration website for the 2015 Belgian Surgical Week. It was a one page long, user friendly document, easy to be filled voluntarily and anonymously.

RESULTS

Among the 206 surgeons who registered, 81 (39%) filled in the SCQ. The SC template proposed by the WHO "Safe Surgery Saves Lives" initiative was used by 91% of the respondents. However, 89% adapted the SC to their local hospital environment, and 87.5% use it personally for their patients. Since implementation, the SC was never adapted in 46%. According to 21% of respondents, an adverse event was avoided thanks to the SC. Amazingly, SC was considered as an administrative burden by 83% despite the same percentage recognized that patients benefited from the SC. Only 28% of respondents got feedback from the use of the SC.

CONCLUSIONS

In this survey, the number of adverse event avoided thanks to the use of the SC demonstrates that SC -represents a simple strategy for addressing surgical patient safety in OT. Nevertheless, SC is still considered by many surgeons as an additional administrative burden and/or as just another gimmick. Further studies are needed to understand why some surgeons are still not willing to adapt to a changing safety culture.

In vitro expansion of U87-MG human glioblastoma cells under hypoxic conditions affects glucose metabolism and subsequent in vivo growth

Hypoxia is a characteristic feature of solid tumors leading to the over expression of hypoxia-inducible factor (HIF)-1α protein and therefore to a specific cellular behavior. However, even though the oxygen tension in tumors is low (<5 %), most of the cell lines used in cancer studies are grown under 21 % oxygen tension. This work focuses on the impact of oxygen conditions during in vitro cell culture on glucose metabolism using 1-(13)C-glucose. Growing U87-MG glioma cells under hypoxic conditions leads to a two- to threefold reduction of labeled glutamine and an accumulation of fructose. However, under both hypoxic and normoxic conditions, glucose is used for de novo synthesis of pyrimidine since the (13)C label is found both in the uracil and ribose moieties. Labeling of the ribose ring demonstrates that U87-MG glioma cells use the reversible branch of the non-oxidative pentose phosphate pathway. Interestingly, stereotactic implantation of U87-MG cells grown under normoxia or mild hypoxia within the striatum of nude mice led to differential growth; the cells grown under hypoxia retaining an imprint of the oxygen adaptation as their development is then slowed down.

Modeling nigrostriatal degeneration in organotypic cultures, a new ex vivo model of Parkinson's disease

Parkinson's disease (PD) is the second most frequent neurodegenerative disorder afflicting 2% of the population older than 65 years worldwide. Recently, brain organotypic slices have been used to model neurodegenerative disorders, including PD. They conserve brain three-dimensional architecture, synaptic connectivity and its microenvironment. This model has allowed researchers a simple and rapid method to observe cellular interactions and mechanisms. In the present study, we developed an organotypic PD model from rat brains that includes all the areas involved in the nigrostriatal pathway in a single slice preparation, without using neurotoxins to induce the dopaminergic lesion. The mechanical transection of the nigrostriatal pathway obtained during slice preparation induced PD-like histopathology. Progressive nigrostriatal degeneration was monitored combining innovative approaches, such as diffusion tensor magnetic resonance imaging (DT-RMI) to follow fiber degeneration and mass spectrometry to quantify striatal dopamine content, together with bright-field and fluorescence microscopy imaging. A substantia nigra dopaminergic cell number decrease was observed by immunohistochemistry against rat tyrosine hydroxylase (TH) reaching 80% after 2 days in culture associated with a 30% decrease of striatal TH-positive fiber density, a 15% loss of striatal dopamine content quantified by mass spectrometry and a 70% reduction of nigrostriatal fiber fractional anisotropy quantified by DT-RMI. In addition, a significant decline of medium spiny neuron density was observed from days 7 to 16. These sagittal organotypic slices could be used to study the early stage of PD, namely dopaminergic degeneration, and the late stage of the pathology with dopaminergic and GABAergic neuron loss. This novel model might improve the understanding of PD and may represent a promising tool to refine the evaluation of new therapeutic approaches.

3-Carboxamido-5-aryl-isoxazoles as new CB2 agonists for the treatment of colitis

Recent investigations showed that anandamide, the main endogenous ligand of CB1 and CB2 cannabinoid receptors, possesses analgesic, antidepressant and anti-inflammatory effects. In the perspective to treat inflammatory bowel disease (IBD), our approach was to develop new selective CB2 receptor agonists without psychotropic side effects associated to CB1 receptors. In this purpose, a new series of 3-carboxamido-5-aryl-isoxazoles, never described previously as CB2 receptor agonists, was designed, synthesized and evaluated for their biological activity. The pharmacological results have identified great selective CB2 agonists with in vivo anti-inflammatory activity in a DSS-induced acute colitis mouse model.

Perfluorocarbon-loaded lipid nanocapsules as oxygen sensors for tumor tissue pO₂ assessment

The assessment of tumor oxygenation is a crucial factor in cancer therapy and may be carried out using fluorine MRI once fluorine probes have been distributed within the tumor. However, the deposit of those highly fluorinated compounds often jeopardizes anatomical image quality and requires emulsification of the probes. Due to the high density and the high lipophilicity of perfluorocarbons, nanoemulsion of these molecules usually requires high-energy processes. In the present work, we discuss the synthesis and the physico-chemical characterization of perfluorocarbon nanocapsules using a low-energy phase-inversion process. The nanocapsules were tested on a mouse tumor brain model to assess oxygenation.

Susceptibility gradient quantization by MRI signal response mapping (SIRMA) to dephaser

PURPOSE

Susceptibility effects are a very efficient source of contrast in magnetic resonance imaging. However, detection is hampered by the fact the induced contrast is negative. In this work, the SIgnal Response MApping (SIRMA) to dephaser method is proposed to map susceptibility gradient to improve visualization.

METHODS

In conventional gradient echo acquisitions, the echo formation of susceptibility affected spins is shifted in k-space, the shift being proportional to the susceptibility gradient. Susceptibility gradients map can be produced by measuring this induced shifts. The SIRMA method measures these shifts from a series of dephased images collected with additional incremental dephasers. These additional dephasers correspond either to a slice refocusing gradient offset or to a reconstruction window off-centering. The signal intensity profile as a function of the additional dephaser was determined on a pixel-by-pixel basis from the ensemble of dephased images. Susceptibility affected voxels presented a signal response profile maximum shifted compared to nonaffected voxels ones. Shift magnitude and sign were measured for each pixel to determine susceptibility gradients and produce a susceptibility gradient map.

RESULTS

In vitro experiments demonstrated the ability of the method to map gradient inhomogeneities induced by a cylinder. Quantization accuracy was evaluated comparing SIRMA images and simulations performed on the well-characterized air filled cylinder model. Performances of the SIRMA method, evaluated in vitro on cylinders filled with various superparamagnetic iron oxide SPIO concentrations, showed limited influence of acquisition parameters. Robustness of the method was then assessed in vivo after an infusion of SPIO-loaded nanocapsules into the rat brain using a convection-enhanced drug delivery approach. The region of massive susceptibility gradient induced by the SPIO-loaded nanocapsules was clearly delineated on SIRMA maps and images were compared to T2* weighted images, Susceptibility Gradient Map (SGM), and histological Perl's staining slice. The potential for quantitative evaluation of SPIO distribution volume was demonstrated.

CONCLUSIONS

The proposed method is a promising technique for a wide range of applications especially in molecular or cellular imaging with respect to its quantitative nature and its computational simplicity.

Evaluating SPIO-labelled cell MR efficiency by three-dimensional quantitative T2* MRI

An in vitro MR-assay for superparamagnetic iron oxide (SPIO) particle cell labelling assessment via three-dimensional quantitative T(2) (*) MR microscopy was proposed. On high-resolution images, and due to the high susceptibility difference between the particles and the surrounding medium, SPIO internalized in cells induces signal loss which may be counted and measured on T(2) (*) maps. The increase in both labelled cell percentage and the average perturbation volume with an added amount of iron in the incubation medium proved that intracellular iron uptake is dependent upon the initial concentration of incubation iron. It also proved that the observed increases in total cellular iron uptake measured by inductively coupled plasma optical emission spectroscopy are due to both an increase in the iron mass per cell and also an increase in labelled cell concentration. MR results were compared with Prussian blue staining histology. The sensitivity of the MR methodology was then used to distinguish labelling differences for two different types of particle coating. The MRI-assay we proposed is a compulsory tool to optimize labelling efficiency in order to improve in vivo cell detection. Key parameters for detection, such as the percentage of cell labelling, the effect on the image for a given amount of internalized iron and labelling distribution among a cell population, are easily obtained. The comparison of different contrast agents for labelling one cell type, the assessment of one type of contrast agent for labelling different cell types and/or the evaluation of labelling strategies, are possible without having recourse to classical methods, and provide improved accuracy, since the principle is based on intracellular relaxivity.

Volumetric assessment of myocardial viability in rats using 3D double contrast enhanced T1 and T2-weighted MRI

OBJECTIVE

Volumetric evaluation of the myocardial viability post-infarction in rats using 3D in vivo MR imaging at 7 T using injection of an extracellular paramagnetic contrast agent and intravascular superparamagnetic iron oxide nanoparticles in the same imaging session.

MATERIALS AND METHODS

Five hours after induction of permanent myocardial infarction in rats (n=6), 3D in vivo T1- and T2-weighted MR Imaging was performed prior to and after Gd-DOTA injection (0.2 mmol/kg) and prior to and after nanoparticle injection (5 mg Fe/kg) to assess infarct size and myocardial viability.

RESULTS

3D MR Imaging using a successive contrast agent injection showed a difference of infarct size after Gd-DOTA injection on T1-weighted images compared to the one measured on T2-weighted images after Gd-DOTA and nanoparticle injection.

CONCLUSION

The use of 3D T1- and T2-weighted MR Imaging using a double contrast agents protocol made possible the accurate characterization of myocardial infarction volume and allowed the detection of myocardial viability post-infarction in rats.

Prenatal evaluation of kidney function in mice using dynamic contrast-enhanced magnetic resonance imaging

Glomerular differentiation starts as soon as embryonic stage 12 in mice and suggests that kidneys may be functional at this stage. Dynamic contrast-enhanced magnetic resonance microscopy, a noninvasive imaging technique, was used to assess renal function establishment in utero. Indeed, in adults (n = 3), an intravenous injection of gadolinium-DOTA induced in a first step a massive and rapid drop in kidney signal intensity followed, in a second step, by a drop in bladder signal intensity. The delay in signal changes between kidney and bladder reflected glomerular filtration. Pregnant mice underwent anatomical and dynamic contrast-enhanced magnetic resonance microscopy on postcoital days 12-13 (n = 2), 13-14 (n = 1), 14-15 (n = 3), 15-16 (n = 2), 16-17 (n = 3), 17-18 (n = 3), and 18-19 (n = 1). Kidneys and bladder were unambiguously depicted prior to contrast agent injection on stage 15-16 embryos. Contrast agent injection allowed kidney, detection as early as stage 12-13 but not bladder. Kinetics of signal changes demonstrated that glomerular filtration is established at embryonic stage 15-16 in mice. Thus, anatomical and dynamic contrast-enhanced magnetic resonance microscopy may be a powerful noninvasive method for in vivo prenatal developmental and functional studies.

Characterization and detection of experimental rat gliomas using magnetic resonance imaging

Two different experimental rat brain tumours (F98 glioma and 9L glioma) were characterized using T1 and T2, apparent diffusion coefficient (ADC) and magnetization transfer ratio (MTR). Even though both tumours appeared homogenous at the early stage of growth, significant differences were measured for all parametric images between tumours and normal brain tissue. Irrespective of the sequence used, tumour lesion/normal parenchyma contrast for the non-infiltrative 9L was twice that of the infiltrative F98 glioma. The use of spin preparation via an inversion pulse in a fast spin echo sequence increases contrast by a factor of 20-30.

Therapeutic efficacy study of novel 5-FU-loaded PMM 2.1.2-based microspheres on C6 glioma

The aim of this study was to evaluate the potential of poly(methylidene malonate 2.1.2) as a new drug delivery system to the central nervous system. 5-Fluorouracil microspheres were formulated by an emulsion-extraction method, and evaluated on a C6 glioma model. Twenty-seven Sprague-Dawley female rats underwent implantation of various C6 cell concentrations. Magnetic resonance imaging was performed at day 10 to control the setting of the tumor, by using a T2-weighted sequence. At day 12, 18 animals received blank or 5-FU-loaded microspheres, while 9 animals were not implanted and constituted the controls. Thereafter, MRI was performed twice a week to follow the tumor growth. In 12 animals, an alloimmune rejection of the tumor was observed, showing the limitations of the C6 glioma model. When tumor developed, no relationship was observed between the number of C6 cells injected and the tumor volume. 5-FU microsphere efficacy could statistically be demonstrated by significantly improving the median survival of C6 glioma-bearing animals and also by decreasing tumor burden.

High field magnetic resonance imaging evaluation of superparamagnetic iron oxide nanoparticles in a permanent rat myocardial infarction

RATIONALE AND OBJECTIVES

The purpose of this study was to evaluate superparamagnetic iron oxide (SPIO) nanoparticles to discriminate infarcted from normal tissue after myocardial infarction using high field MR imaging (7 tesla).

MATERIALS AND METHODS

Permanent myocardial infarction was induced in rats. SPIO nanoparticles (1 mg Fe/kg) were assessed with T1-weighted gradient echo sequence to visualize the myocardial infarction 48 hours after ligature (n = 6). Furthermore, MR Imaging was performed using a T2-weighted RARE sequence and nanoparticles were injected (5 or 10 mg Fe/kg) on 36 rats 5, 24 or 48 hours after infarction.

RESULTS

No changes in contrast between normal and infarcted myocardium was observed after nanoparticle injection on T1-weighted images. However, nanoparticles induced a significant contrast increase between normal and infarcted myocardium on T2-weighted images whatever the delay between infarction and imaging (2.99 +/- 1.66 preinjection vs. 7.82 +/- 1.96 after SPIO injection at a dose of 5 mg Fe/kg 5 hours postinfarction, P = 0.0001).

CONCLUSIONS

Nanoparticle injection made it possible to discriminate normal from infarcted myocardium on T2-weighted images. However, the high magnetic field prevented the visualization of the T1 effect of SPIO nanoparticles.

In utero time-course assessment of mouse embryo development using high resolution magnetic resonance imaging

Magnetic resonance microscopy, a non-invasive imaging technique was used for a longitudinal follow-up of mouse embryonic development in utero and for the assessment of embryonic kidney function using 50 nm magnetite dextran particles. Even though the morphologic proton images obtained were still far from classical histological slices quality, an in-plan resolution of 195 microm was achieved for a slice thickness of 800 microm. Mouse embryos sub-structures such as the fourth ventricle, the mesencephalic vesicle, the aorta or the liver can be revealed as early as E11/12. Heart, diaphragm, spinal cord, third, fourth and lateral ventricles were unambiguously seen at E13/14; whereas skeleton, tail, kidney and digit can only be seen from E15/16. Kidney and bladder were certainly identified from E16 on. MR microscopy offers a possibility for in utero phenotyping of mice and can therefore be a powerful tool for post-genomic applications.

Quantitative MR renography using a calibrated internal signal (ERETIC)

To measure MR renograms, cortical and medullary kidney signal intensity evolution is followed after contrast agent injection. To obtain an accurate quantitative signal measurement, the use of a reference signal is necessary to correct the potential MRI system variations in time. The ERETIC method (Electronic Reference To access In vivo Concentrations) provides an electronic reference signal. It is synthesized as an amplitude modulated RF pulse applied during the acquisition. The ERETIC method was as precise as the external tube reference method but presents major advantages like its free adjustability (shape, location and magnitude) to the characteristics of the organ studied as well as its not taking room inside the magnet. Even though ERETIC showed a very good intrinsic stability, systems' variations still affect its signal in the same way as real NMR signals are affected. This method can be easily implemented on any imaging system with two RF channels.

Is magnetic resonance imaging texture analysis a useful tool for cell therapy in vivo monitoring?

Assessment of anti-tumor treatment efficiency is usually done by measuring tumor size. Treatment may however induce changes in the tumor other than tumor size. Magnetic Resonance Imaging Texture Analysis (MRI-TA) is presently used to follow activated lymphocyte cell therapy. We used a 7T microimager to acquire high-resolution MR images of an experimental liver metastasis from colon carcinoma in rats treated (n = 4) or not (n = 3) with a cell therapy product. MRI-TA was then performed with Linear Discriminant Analysis and showed: i) a significant variation of tumor texture with tumor growth and ii) a significant modification in the texture of tumors treated with activated lymphocytes compared with untreated tumors. T2-weighted images or volume calculation did not evidence any difference. MRI-TA appears as a promising method for early detection and follow-up of response to cell therapy.

Therapeutic efficacy of 5-fluorouracil-loaded microspheres on rat glioma: a magnetic resonance imaging study

The aim of this work was to assess the therapeutic efficacy of an intratumoral bolus injection of 5-fluorouracil (FU) compared to that of drug loaded in biodegradable microspheres, for the treatment of brain tumour. Experiments were carried out using a fast-growing C6-glioma rat model. The therapeutic protocols were performed 12 days after the injection of glioma cells. At this stage, the tumours were installed and the mean volume was 13 +/- 2 microl as measured by proton magnetic resonance (MR) imaging. This technique was used for the follow-up of the tumour volume with respect to time and therapy. In terms of rat survival, both therapies induced a significant 50% increase in animal life span (p < 0.05) compared to animals receiving no drug or unloaded microspheres. Whilst no cure was observed, analysis of the MR images showed that the local and sustained delivery of FU slowed the tumour development in the vicinity of the microspheres by a factor of 3, compared with the bolus intratumoral injection.

In vivo quantitative microimaging of rat spinal cord at 7T

In vivo T(2), ADC, and MT properties of the GM and WM of the rat spinal cord were measured at 7T in the cervical region. The GM T(2), T(2GM) = 43.2 +/- 1.0 msec is significantly reduced compared to the WM T(2), T(2WM) = 57.0 +/- 1.6 msec. Diffusion is anisotropic for both GM and WM, with a larger ADC value along the cord axis (ADC(GM//) = 1.05 +/- 0.09 10(-9) m(2)sec(-1) and ADC(WM//) = 1.85 +/- 0.18 10(-9) m(2)sec(-1)) than perpendicular to this plane (ADC(GM)( perpendicular) approximately 0.50 * 10(-9) m(2)sec(-1) and ADC(WM)( perpendicular) approximately 0.18 * 10(-9) m(2)sec(-1)). The MT properties do not significantly differ between the WM and the GM, but allow one to distinguish the thin CSF layer from the WM. DWI with the sensitizing gradient perpendicular to the cord axis leads to the best contrast between GM and WM in the cervical region.

An in-vivo magnetic resonance imaging study of the olfactory bulbectomized rat model of depression

The olfactory bulbectomized (OB) rat is a well-accepted animal model of depression. The present magnetic resonance imaging (MRI) investigation demonstrates alterations in signal intensities in cortical, hippocampal, caudate and amygdaloid regions in OB animals, but not in sham operated controls. Ventricular enlargement was also evident in OB animals. These alterations have implications with regard to the face and construct validity of this model.

High-field quantitative transverse relaxation time, magnetization transfer and apparent water diffusion in experimental rat brain tumour

The potential of quantitative parameter images of transverse relaxation time T(2), apparent diffusion coefficient (ADC) and magnetization transfer ratio (MTR) to characterize experimental brain tumours was studied. Necrosis or haemorrhage can be detected using either MTR, ADC or T(2) (necrosis-MTR reduced by 35%, ADC and T(2) increased respectively by 170% and 100% compared with normal brain tissue; haemorrhage-MTR increased by 60%, ADC and T(2) decreased by 40% and 20%, respectively). Normal brain tissue can only be distinguished from tumour on T(2) and MTR parameter images. However, for small tumours (10 microl), the best contrast is observed with MTR, ca. 30%, whereas for T(2) the contrast is ca. 10%.

Pax genes and the differentiation of hormone-producing endocrine cells in the pancreas

Despite the pivotal role of the pancreas in hormonally-regulated pathways in the body, e.g. glucose homeostasis, the genetic mechanisms defining it have for many years remained largely enigmatic. After years out of the spotlight, pancreas development has once again come to centre stage. To a large extent, this is due to recent advances made through the detailed analysis of transgenic mice which have been engineered to carry mutations in specific developmental control genes. This review specifically focuses on the specification of the endocrine pancreas lineage and in particular on the role of the developmental control genes Pax4 and Pax6 in the generation of specific endocrine cell types. The comparison of various phenotypes of different mouse mutants affecting endocrine development supports a model in which Pax4 and Pax6 are required for the differentiation of certain endocrine cell lineages and implies a potential for acting at different levels of endocrine development.

MRI study of transient cerebral ischemia in the gerbil: interest of T2 mapping

RATIONALE AND OBJECTIVES

The aim of this study was to evaluate the diagnostic use of MRI and, more precisely, the use of quantitative T2 imaging at 7 T for the early detection of neuronal cerebral alterations after transient ischemia in the gerbil.

METHODS

One hundred forty-seven Mongolian gerbils were separated into four groups for which a bicarotid artery occlusion lasted for 4, 6, 8, or 10 minutes, respectively. The animals were scanned before carotid artery occlusion and at 3, 6, 10, 24, and 48 hours and 5 days after the ischemic incident. MR images were acquired on a Bruker Avance DRX300 mini-imaging system.

RESULTS

Our results show that T2 mapping is able to localize brain damage induced by transient ischemia and to detect early perturbations in water content (as early as 6 hours after ischemia).

CONCLUSIONS

T2 measurements in the striata are correlated with the severity of the ischemic incident, since the changes observed on the T2 images are directly proportional to the duration of occlusion.

Improving the detection of low concentration metabolites in magnetic resonance spectroscopy by digital filtering

In vivo detection and quantitation of metabolites is often limited by their low concentration. As far as magnetic resonance spectroscopy (MRS) is concerned, detection and quantitation can be significantly improved by reduction of the observed spectral width (SW). The reduction is limited to the spreading of resonances in the bandwidth unless high performance digital filters are used. Indeed, these filters avoid the folding of unwanted resonances such as water peak into the main frequency spectrum and therefore allow reduction of the spectral width to its optimal value. These filters are now available on most MRS systems but their use is not common even if, as we show in the particular case of proton MRS, a significant increase in signal-to-noise ratio (two-fold factor for SW reduction from 5000 Hz to 1351 Hz) can be achieved. This signal-to-noise improvement allows better quantitation accuracy.

Assessment of induced rat mammary tumour response to chemotherapy using the apparent diffusion coefficient of tissue water as determined by diffusion-weighted 1H-NMR spectroscopy in vivo

Chemosensitivity of N-methyl-N-nitrosourea-induced rat mammary tumours treated with 5-fluorouracil at a dose of 100 mg kg(-1) i.p. was assessed by using diffusion-weighted 1H-MRS to measure the average diffusion coefficient (ADC) of water in the tumour tissue. ADC measurements prior to any therapy correlated positively with necrotic fraction. Tumours with low initial ADC (< 0.95 x 10(9) m2 s(-1)) showed an increase in ADC 7 days after treatment, whereas tumours with a high initial ADC (> 1.2 x 10(9) m2 s(-1)) showed a decrease. All tumours decreased significantly in volume (P < 0.05) 2, 5 and 7 days after treatment. At day 7 post-treatment, tumours with a high pre-treatment ADC started to regrow. The initial ADC value, as well as changes after treatment predict tumour chemosensitivity, which could be clinically relevant.

Gastrulation and homeobox genes in chick embryos

We review the early stages of chick embryogenesis, in particular the formation of the hypoblast, and the ingression of endoderm and mesoderm through the primitive streak. The formation of a trilaminar embryo during gastrulation is accompanied by the specification of body axes. The first axis is already present in the unfertilized egg and runs from the cytoplasmatic animal to the yolk rich vegetal pole. Already within the uterus a second axis conveys bilateral symmetry to the embryo. It extends from a dorsal/anterior to a ventral/posterior position. These axial poles segregate during gastrulation to form the classical coordinates, a dorsal-ventral and an anterior-posterior axis. The establishment of axes is accompanied by the expression of specific combinations of homeobox genes during gastrulation in the chick, as in other metazoa. We review the avian specific information and compare it with findings in other species. A combinatorial homeobox code for the specification of identities during development is discussed.

Segregating expression domains of two goosecoid genes during the transition from gastrulation to neurulation in chick embryos

We report the isolation and characterization of a chicken gene, GSX, containing a homeobox similar to that of the goosecoid gene. The structure of the GSX gene and the deduced GSX protein are highly related to the previously described goosecoid gene. The two homeodomains are 74% identical. In the first few hours of chick embryogenesis, the expression pattern of GSX is similar to GSC, in the posterior margin of the embryo and the young primitive streak. Later during gastrulation, expression of the two genes segregate. GSC is expressed in the anterior part of the primitive streak, then in the node, and finally in the pre-chordal plate. GSX is expressed in the primitive streak excluding the node, and then demarcating the early neural plate around the anterior streak and overlying the pre-chordal plate. We demonstrate that the GSX-positive part of the primitive streak induces gastrulation, while the GSC-expressing part induces neurulation. After full extension of the streak, the fate of cells now characterized by GSX is to undergo neurulation, while those expressing GSC undergo gastrulation. We discuss the effect of a duplicated basic goosecoid identity for the generation of a chordate nervous system in ontogeny and phylogeny.

Checklist: vertebrate homeobox genes

Up to now around 170 different homeobox genes have been cloned from vertebrate genomes. A compilation of the various isolates from mouse, chick, frog, fish and man is presented in the form of a concise checklist, including the designations from the original publications. Putative homologs from different species are aligned, and key characteristics of embryonic or adult expression domains, as well as mutant phenotypes are briefly indicated.

Developmentally regulated mouse gene NK10 encodes a zinc finger repressor protein with differential DNA-binding domains

Using oligonucleotides complementary to the conserved inter-finger region of a variety of previously described zinc finger-encoding genes, a novel mouse gene was cloned and characterized. The gene is localized on chromosome 8 and comprises five exons. Its corresponding mRNA is developmentally regulated in various tissues and includes an open reading frame encoding a protein of 72,422 daltons. It shares amino-terminal homologies with human KRAB (or FPB) boxes, and contains 13 zinc fingers of the C2-H2 type. The NK10 KRAB domains exhibit repressing activity when tested in GAL4 fusion protein assays. Cloning of putative target sequences revealed that the individual domains differentially contribute to zinc-dependent target DNA binding.

Male germ cell extracts contain proteins binding to the conserved 3'-end of mouse p68 RNA helicase mRNA

The 3'-untranslated regions of human and mouse p68 RNA helicase mRNA are highly conserved, suggesting a functional role of the nucleic acid sequence itself in regulation of p68 RNA helicase expression. Secondary structure evaluations revealed no indications for a predominant folding pattern within the 3'-UTR. To test the potential of the 3'-sequence to serve as a target for specific binding proteins, gel shift assays were performed. In vitro-synthesized RNA was incubated with cytoplasmic as well as nuclear extracts from mouse male germ cells. Evidence was obtained that such specific proteins exist in germ cell extracts. Photo-crosslinking experiments suggested that a 30 kDa protein was involved in these binding events.

Assignment to chromosome 11 of mouse p68 RNA helicase gene (Hlr1) and pseudogene (Hlr1-ps1)

The gene encoding murine p68 RNA helicase (Hlr1) was mapped to the distal portion of mouse chromosome 11 by linkage analysis of DNA restriction length polymorphisms using an interspecific genetic backcross between (C57BL/6J x SPRET/Ei) F1 hybrids and SPRET/Ei mice. A closely related gene (Hlr1-ps1) was identified, isolated, and mapped to the proximal part of the same chromosome. Sequence analysis and PCR results suggest that Hlr1-ps1 is a pseudogene, flanked by DNA stretches similar to mouse insertion element IE118.

[Cardiotoxicity of 5-fluorouracil: a question of formulation]

The cardiotoxicity of 5-fluorouracil (FU) was attributed to degradation compounds present in the injected vials, fluoroacetaldehyde (Facet) and fluoromalonaldehydic acid (FMald). These compounds are formed with time in the basic medium necessary to solubilize FU. FU-NaOH vials were much less cardiotoxic than FU-Tris vials on the isolated perfused rabbit heart model since, in FU-Tris vials, Facet and FMald are stored in stable "depot" forms, which are adducts with Tris, whereas, in FU-NaOH vials, they are extensively chemically transformed. Cardiotoxic fluoroacetate (FAC), arising from Facet metabolization, was found in urine of patients, with a ratio FAC/FU catabolites 10-30 fold lower in patients treated with FU-NaOH than in those treated with FU-Tris.

Chromosomal assignment of three novel mouse genes expressed in testicular cells

The chromosomal positions of three genes that are selectively expressed in mouse testis cells have been identified. These genes include (i) TAZ83, which codes for an early- to mid-pachytene germ cell stage-expressed, cysteine-rich transmembrane protein (cyritestin) with homologies to various snake toxins and guinea pig sperm-egg fusion proteins; (ii) TNZ1, which is expressed in neonatal Leydig cells; and (iii) TAZ4, a testis-specific gene isolated by immunoscreening with antiserum raised against Sertoli cell membranes. Our experimental data, derived from chromosomal in situ hybridizations and RFLP studies of genetic backcrosses, indicate that (i) the TAZ83 (cyritestin) gene maps to chromosome 8, band A2, near the Plat locus; (ii) TNZ1 is located in the proximal region of chromosome 11; and (iii) TAZ4 is located at band D in the distal portion of chromosome 11, near the Hlr1 locus, with a related sequence, TAZ4-rs1, in the proximal part of chromosome 1.

The tris formulation of Fluorouracil is more cardiotoxic than the sodium-salt formulations

The cardiotoxicity of 5-fluorouracil (FU) was attributed to degradation compounds present in the injected vials, fluoroacetaldehyde (Facet) and fluoromalonaldehydic acid (FMald). FU-NaOH vials were much less cardiotoxic than FU-Tris vials on the isolated perfused rabbit heart model since Facet and FMald are stored in stable depot forms in FU-Tris vials whereas, in FU-NaOH vials, they are extensively transformed. Cardiotoxic fluoroacetate (FAG), coming from Facet metabolization, was found in urine of patients, with a ratio FAC /FU catabolites 10-30 fold lower in patients treated with FU-NaOH than in those treated with FU-Tris.

High-level expression in male germ cells of murine P68 RNA helicase mRNA

The complete cDNA coding for mouse P68 RNA helicase was cloned and its nucleotide sequence was determined. The sequence is about 95% identical to the human equivalent. Whereas the 5'-untranslated region is less conserved (71%), the 3'-ends of mouse and human mRNAs are nearly identical. Between stop codon and poly(A)-tail both sequences are 97% conserved. At the level of amino acid sequence, the similarity of both, mouse and human, DEAD box family proteins is as high as 98%. In situ hybridizations using cDNA subfragments as probes revealed a testis-selective expression of P68 RNA helicase mRNA. The signal was restricted to late pachytene spermatocytes and haploid spermatids. Northern blot analyses corroborated these results but suggested that expression of related mRNA species occurs in a variety of other tissues.

Cardiotoxicity of high-dose continuous infusion fluorouracil: a prospective clinical study

PURPOSE

A prospective clinical study was performed to determine the incidence of high-dose continuous intravenous infusion fluorouracil (5FU-CIV) cardiotoxicity.

PATIENTS AND METHODS

Three hundred sixty-seven patients who were given first-cycle high-dose 5FU-CIV were monitored for cardiac function by clinical examination, ECG, and laboratory tests. 5FU-CIV was administered during a 96- or 120-hour period at doses that ranged from 600 to 1,000 mg/m2/d. Associated drugs included cisplatin (56%), mitomycin (12.5%), folinic acid (leucovorin) (7%), and others (14%). Thirty-nine patients (10.5%) received 5FU as a single agent.

RESULTS

5FU-induced cardiac events occurred in 28 patients (7.6%; 95% confidence interval, 4.9% to 10.3%). Nine of them had a history of cardiac disease. Primary tumors included head and neck (n = 13), gastrointestinal (n = 6), breast (n = 3), and others (n = 6). The mean onset time of cardiac symptoms was 3 days (range, 2 to 5). Inaugural symptoms included angina pectoris (n = 18), hypotension (n = 6), hypertension (n = 5), malaise (n = 4), dyspnea (n = 2), arrhythmia (n = 1), or sudden death (n = 1). At 5FU discontinuation, six patients' cardiac symptoms returned to baseline, but 21 patients experienced unstable angina (n = 8), hypotension/cardiovascular collapse (n = 11), pulmonary edema (n = 1), or sudden death (n = 4). The lethality rate was 2.2% (five sudden deaths plus three irreversible collapses). ECG showed repolarization changes (ST segment deviation; T-wave inversion) in 65% and/or diffuse microvoltage in 22% of the patients who presented with cardiac events. Echocardiography showed partial or global hypokinesia in nine of the 16 patients who were examined, and one case of prolonged akinesia. Cardiac enzymes rarely showed an increase (n = 2). In severe but reversible cases, clinical, ECG, and echographic parameters returned to baseline status within 48 hours after the drug discontinuation. A fluorine 19 nuclear magnetic resonance (19F NMR) analysis of urine was performed on 14 patients; six had cardiac symptoms and eight did not. Fluoroacetate (FAC), a known cardiotoxic compound, was detected in all cases.

CONCLUSION

In our study, the incidence of high-dose 5FU-CVI cardiotoxicity was 7.6%. The hypothesis of a toxic cardiomyopathic process requires further confirmation.

Cardiotoxicity of commercial 5-fluorouracil vials stems from the alkaline hydrolysis of this drug

The cardiotoxicity of 5-fluorouracil (FU) was attributed to impurities present in the injected vials. One of these impurities was identified as fluoroacetaldehyde which is metabolised by isolated perfused rabbit hearts into fluoroacetate (FAC), a highly cardiotoxic compound. FAC was also detected in the urine of patients treated with FU. These impurities were found to be degradation products of FU that are formed in the basic medium employed to dissolve this compound. To avoid chemical degradation of this antineoplastic drug, the solution of FU that will be injected should be prepared immediately before use.

Characterization by enriched polyclonal antibodies of developmentally regulated and cell type specific mouse testis antigens

Polyclonal antisera directed against testicular proteins were characterized by immunocytochemistry and Western blot analysis. Antibodies binding to testis-specific, developmentally regulated protein bands were eluted from their antigens and used for further characterization of the developmental profile and cell type-specific expression of two antigens, PSM33 and NNA75. While PSM33 was found to be present in spermatocytes from the late pachytene stage on, NNA75 could be localized in neonatal interstitial cells. NNA75 expression ceases by to postnatal day ten, when first meiosis starts within the seminiferous tubules, thus suggesting an interactive role of Leydig cells during the onset of meiotic divisions.