Bud abortion in tulip bulbs studied by magnetic resonance imaging.

After storage and subsequent planting of flower bulbs, the flower bud frequently appears to be aborted. This physiological aberration is probably caused by a change in the water status of the bulb and may be initiated during storage. The development of bud abortion in tulip bulbs was studied during long-term dry storage of the bulbs at 5 degrees C.

Characterization of the normal cardiac myofiber field in goat measured with MR-diffusion tensor imaging.

Cardiac myofiber orientation is a crucial determinant of the distribution of myocardial wall stress. Myofiber orientation is commonly quantified by helix and transverse angles. Accuracy of reported helix angles is limited.

The quantitation of ADP diffusion gradients across the outer membrane of heart mitochondria in the presence of macromolecules.

We have previously provided evidence that diffusion of metabolites across the porin pores of mitochondrial outer membrane is hindered. A functional consequence of this diffusion limitation is the dynamic compartmentation of ADP in the intermembrane space. These earlier studies were done on isolated mitochondria suspended in isotonic media without macromolecules, in which intermembrane space of mitochondria is enlarged.

Improved subtraction by adiabatic FAIR perfusion imaging.

For pulsed arterial spin labeling techniques (e.g., FAIR), mismatches between the imaging and inversion slice profile result in a nonperfusion-related offset.

Application of magnetic resonance to animal models of cerebral ischemia.

The present review has been compiled to highlight the role of magnetic resonance imaging (MRI) and MR spectroscopy (MRS) for the investigation of cerebral ischemia in the animal experimental field of basic research. We have focused on stroke investigations analyzing the pathomechanisms of the disease evolution and on new advances in both nuclear MR (NMR) methodology or genetic engineering of transgenic animals for the study of complex molecular relationships and causes of the disease. Furthermore, we have tried to include metabolic and genetic aspects, as well as the application of functional imaging, for the investigation of the disturbance or restitution of functional brain activation under pathological conditions as relates to controlled animal experiments.

Exogenous anandamide protects rat brain against acute neuronal injury in vivo.

The endocannabinoid anandamide [N-arachidonoylethanolamine (AEA)] is thought to function as an endogenous protective factor of the brain against acute neuronal damage. However, this has never been tested in an in vivo model of acute brain injury. Here, we show in a longitudinal pharmacological magnetic resonance imaging study that exogenously administered AEA dose-dependently reduced neuronal damage in neonatal rats injected intracerebrally with the Na(+)/K(+)-ATPase inhibitor ouabain.

Neuroprotection by Delta9-tetrahydrocannabinol, the main active compound in marijuana, against ouabain-induced in vivo excitotoxicity.

Excitotoxicity is a paradigm used to explain the biochemical events in both acute neuronal damage and in slowly progressive, neurodegenerative diseases. Here, we show in a longitudinal magnetic resonance imaging study that Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the main active compound in marijuana, reduces neuronal injury in neonatal rats injected intracerebrally with the Na(+)/K(+)-ATPase inhibitor ouabain to elicit excitotoxicity. In the acute phase Delta(9)-THC reduced the volume of cytotoxic edema by 22%.

Single-shot diffusion trace (1)H NMR spectroscopy.

Ignoring diffusion anisotropy can severely hamper the quantitative determination of water and metabolite diffusion in complex tissues. The measurement of the trace of the diffusion tensor provides unambiguous and rotationally invariant ADC values, but usually requires three separate experiments. A single-shot technique developed earlier, originally designed for diffusion trace MR imaging (Mori and van Zijl, Magn Reson Med 1995;33:41-52), was improved and adapted for diffusion trace MR spectroscopy.

Diffusion NMR spectroscopy.

MR offers unique tools for measuring molecular diffusion. This review focuses on the use of diffusion-weighted MR spectroscopy (DW-MRS) to non-invasively quantitate the translational displacement of endogenous metabolites in intact mammalian tissues. Most of the metabolites that are observed by in vivo MRS are predominantly located in the intracellular compartment.

Cerebral metabolism in streptozotocin-diabetic rats: an in vivo magnetic resonance spectroscopy study.

Aims/hypothesis: It is increasingly evident that the brain is another site of diabetic end-organ damage. The pathogenesis has not been fully explained, but seems to involve an interplay between aberrant glucose metabolism and vascular changes. Vascular changes, such as deficits in cerebral blood flow, could compromise cerebral energy metabolism.

Two-voxel localization sequence for in vivo two-dimensional homonuclear correlation spectroscopy.

The combination of localized 2D 1H MR correlation spectroscopy and Hadamard encoding allows the simultaneous acquisition of multiple volumes of interest without an increase in the experimental duration, compared to single-voxel acquisition. In the present study, 2D correlation spectra were acquired simultaneously within 20 to 40 min in two voxels located in each hemisphere of the rat brain. An intervoxel distance of 20% of the voxel size was sufficient to limit spatial contamination.

On the importance of exchangeable NH protons in creatine for the magnetic coupling of creatine methyl protons in skeletal muscle.

The methyl protons of creatine in skeletal muscle exhibit a strong off-resonance magnetization transfer effect. The mechanism of this process is unknown. We previously hypothesized that the exchangeable amide/amino protons of creatine might be involved.

Magnetic coupling between water and creatine protons in human brain and skeletal muscle, as measured using inversion transfer (1)H-MRS.

Using the inversion transfer technique, the possible magnetic coupling between water protons and the protons of low-molecular weight metabolites was investigated in human brain and skeletal muscle at 1.5 T. The localized (1)H-MR spectra were recorded at different times after selective inversion of the water resonance.

Losartan versus enalapril on cerebral edema and proteinuria in stroke-prone hypertensive rats.

Stroke-prone spontaneously hypertensive rats (SHRSP), subjected to high NaCl, show severe hypertension, organ damage, and early death. Preventive treatment with angiotensin II type 1 (AT1) receptor antagonists is known to be effective. Previously, we found that angiotensin converting enzyme (ACE) inhibition could reduce cerebral edema when treatment was started after manifestation of either proteinuria or cerebral edema.

Post-mortem high-resolution MRI of the spinal cord in multiple sclerosis: a correlative study with conventional MRI, histopathology and clinical phenotype.

We used high-resolution MRI to study the post-mortem appearance of spinal cord multiple sclerosis in relation to histopathology and low-resolution images. Fifty-nine 3 cm long formalin-fixed spinal cord specimens from 19 multiple sclerosis patients and three controls were studied. Clinical characteristics of each patient were reviewed.

Monitoring water content in deforming intervertebral disc tissue by finite element analysis of MRI data.

Mechanical loading, occurring during normal daily life, causes fluid to be expelled from intervertebral discs. Excessive fluid loss during heavy loading might make the disc more vulnerable to damage. In this study, fluid loss was investigated in vitro through monitoring the loss of MRI signal intensity in four bovine coccygeal intervertebral discs, compressed at 2000 N during 1.

Myelin/oligodendrocyte glycoprotein-induced autoimmune encephalomyelitis in common marmosets: the encephalitogenic T cell epitope pMOG24-36 is presented by a monomorphic MHC class II molecule.

Immunization of common marmosets (Callithrix jacchus) with a single dose of human myelin in CFA, without administration of Bordetella pertussis, induces a form of autoimmune encephalomyelitis (EAE) resembling in its clinical and pathological expression multiple sclerosis in humans. The EAE incidence in our outbred marmoset colony is 100%. This study was undertaken to assess the genetic and immunological basis of the high EAE susceptibility.

1H and (31)P magnetization transfer studies of hindleg muscle in wild-type and creatine kinase-deficient mice.

The authors addressed the hypothesis that interactions with creatine kinase (CK) play a role in the off-resonance magnetization transfer (MT) effect of creatine in skeletal muscle. Toward that aim, (1)H MT studies were done on hindleg muscle in wild-type mice and in transgenic mice, lacking cytoplasmic CK and/or mitochondrial CK. The (1)H MT effect was essentially identical in wild-type muscle and the two single CK knock-out muscles, while moderately decreased in tissue lacking both CK isoforms.

In vivo glucose detection by homonuclear spectral editing.

A frequency-selective multiple-quantum-coherence spectral editing pulse sequence, Ssel-MQC, was implemented for the detection of the betaH1-glucose resonance at 4.63 ppm in rat brain in vivo. Unwanted signal suppression and glucose coherence transfer pathway selection were performed with magnetic field gradients.

In vivo (31)P-NMR diffusion spectroscopy of ATP and phosphocreatine in rat skeletal muscle.

The aim of this study was to measure the diffusion of ATP and phosphocreatine (PCr) in intact rat skeletal muscle, using (31)P-NMR. The acquisition of the diffusion-sensitized spectra was optimized in terms of the signal-to-noise ratio for ATP by using a frequency-selective stimulated echo sequence in combination with adiabatic radio-frequency pulses and surface coil signal excitation and reception. Diffusion restriction was studied by measuring the apparent diffusion coefficients of ATP and PCr as a function of the diffusion time.

Direct evidence for the control of mitochondrial respiration by mitochondrial creatine kinase in oxidative muscle cells in situ.

The efficiency of stimulation of mitochondrial respiration in permeabilized muscle cells by ADP produced at different intracellular sites, e.g. cytosolic or mitochondrial intermembrane space, was evaluated in wild-type and creatine kinase (CK)-deficient mice.

NMR spectroscopic evaluation of cerebral metabolism in hydrocephalus: a review.

Cerebral ischemia contributes to cerebral damage in hydrocephalus. Many studies have reported changes in cerebral blood flow and metabolism, supporting this hypothesis. Magnetic resonance spectroscopy (MRS) enables us to investigate cerebral metabolism in a non-invasive and longitudinal manner, thereby providing a promising way of evaluating pathophysiological changes in experimental and clinical hydrocephalus.

Phosphorylation state of red and white muscle in tilapia during graded hypoxia: an in vivo (31)P-NMR study.

The aim of this study was to measure the energetic consequences of hypoxia in different types of skeletal muscle within a single tilapia species (n = 5). To that aim, 81.0 MHz (31)P-nuclear magnetic resonance (NMR) spectra were collected, alternately, from three surface coils placed adjacent to the tissues of interest (dorsal white muscle, ventral white muscle, and lateral red muscle) during a graded hypoxia load over 6 h followed by a 5-h recovery period.

Correlation between tissue depolarizations and damage in focal ischemic rat brain.

Ischemia-induced depolarizations may play a key role in the development of cerebral ischemic injury. Our goal was to assess the relationship between tissue depolarizations and tissue damage in focal ischemia. We performed multi-electrode cortical direct current (DC) potential recording and, subsequently, diffusion-weighted and T(2)-weighted magnetic resonance imaging (MRI) in rats after i) cortical application of KCl, and ii) permanent and transient middle cerebral artery (MCA)-occlusion in rats.

Cerebral metabolism in experimental hydrocephalus: an in vivo 1H and 31P magnetic resonance spectroscopy study.

Object: Brain damage in patients with hydrocephalus is caused by mechanical forces and cerebral ischemia. The severity and localization of impaired cerebral blood flow and metabolism are still largely unknown. Magnetic resonance (MR) spectroscopy offers the opportunity to investigate cerebral energy metabolism and neuronal damage noninvasively and longitudinally.