High-dose enzyme replacement therapy attenuates cerebroventriculomegaly in a mouse model of mucopolysaccharidosis type II.

The natural progression of the severe form of mucopolysaccharidosis II in children is a rapid decline of neurodevelopmental function with hydrocephalus. Recombinant human iduronate-2-sulfatase enzyme replacement therapy (ERT) under a standard regimen seems to have limited effect. Therefore, we determined whether early, high-dose ERT attenuated ventriculomegaly and histologic abnormalities in the brains of IdS-knockout mice. IdS-knockout mice received saline or recombinant human IdS (0.5/1.0/2.0 mg kg(-1)) intravenously once weekly, starting at 4 weeks of age and continuing until 20 weeks. ERT with 2.0 mg kg(-1), but not 0.5 or 1.0 mg kg(-1), significantly attenuated enlarged ventricles, as confirmed by in vivo 7-teslar brain magnetic resonance image (MRI) at 20 weeks. However, neuronal cytoplasmic vacuolization and morphological alteration in the purkinje cells on brain histology and glycosaminoglycan (GAG) levels in brain homogenates were reduced in mice receiving ERT at lower dose than 2.0 mg kg(-1). Additionally, GAG levels significantly correlated with the percent volume ratio of ventricle to whole brain. These results suggested that high-dose systemic ERT started early in life could be a promising therapeutic modality for improving neurologic dysfunction including ventriculomegaly in children with severe Hunter syndrome.

Similar neuroprotective effects of ischemic and hypoxic preconditioning on hypoxia-ischemia in the neonatal rat: a proton MRS study.

The aim of this study was to evaluate the effect of ischemic and hypoxic preconditioning on hypoxia-ischemia (HI) in the neonatal rat. Seven-day-old Sprague-Dawley rats were divided into four groups: control, sham, ischemic preconditioning, and hypoxic preconditioning. Ischemic preconditioning with a 10-min occlusion of the right carotid artery and hypoxic preconditioning with 4-h of hypoxia (8% oxygen) were performed 24-h before HI. For HI, all rats underwent right carotid artery ligature, followed by 2.5-h of hypoxia. Proton magnetic resonance spectroscopy ((1)H MRS) and TUNEL staining were evaluated at 1 and 7 days after HI. At 2 weeks after HI, all rats were sacrificed for morphological analysis. The lipid (Lip), N-acetyl aspartate (NAA), creatine (Cr), and choline-ratios were calculated and compared with TUNEL staining and brain morphologies. Both the ischemic and hypoxic preconditioning groups showed lower Lip/NAA and Lip/Cr ratios and morphological scores, and fewer TUNEL-positive cells than the control and sham groups (P < 0.05). There were no significant differences between the two preconditioning groups. In addition, the ratios correlated with the TUNEL staining and the degrees of morphological changes in all of the groups (P < 0.05). These results suggest that ischemic and hypoxic preconditioning in neonatal rats with HI similarly attenuate brain injury. Moreover, Lip/NAA and Lip/Cr ratios may be used as markers for assessing the extent of brain damage.

Quantitative in vivo detection of brain cell death after hypoxia ischemia using the lipid peak at 1.3 ppm of proton magnetic resonance spectroscopy in neonatal rats.

This study was performed to determine the accuracy of proton magnetic spectroscopy ((1)H-MRS) lipid peak as a noninvasive tool for quantitative in vivo detection of brain cell death. Seven day-old Sprague Dawley rats were subjected to 8% oxygen following a unilateral carotid artery ligation. For treatment, cycloheximide was given immediately after hypoxic ischemia (HI). Lipid peak was measured using (1)H-MRS at 24 hr after HI, and then brains were harvested for fluorocytometric analyses with annexin V/propidium iodide (PI) and fluorescent probe JC-1, and for adenosine-5'-triphosphate (ATP) and lactate. Increased lipid peak at 1.3 ppm measured with (1)H-MRS, apoptotic and necrotic cells, and loss of mitochondrial membrane potential (ΔΨ) at 24 hr after HI were significantly improved with cycloheximide treatment. Significantly reduced brain ATP and increased lactate levels observed at 24 hr after HI showed a tendency to improve without statistical significance with cycloheximide treatment. Lipid peak at 1.3 ppm showed significant positive correlation with both apoptotic and necrotic cells and loss of ΔΨ, and negative correlation with normal live cells. Lipid peak at 1.3 ppm measured by (1)H-MRS might be a sensitive and reliable diagnostic tool for quantitative in vivo detection of brain cell death after HI.

Graft rejection in the xenogeneic transplantation of mice: diagnosis with in vivo MR imaging using the homing trait of macrophages.

BACKGROUND: To evaluate the feasibility of magnetic resonance (MR) imaging to depict the in vivo recruitment of superparamagnetic iron oxide (SPIO)-labeled macrophages and to diagnose graft rejection in xenogeneic transplantation. METHODS: We transplanted the trachea of SD rat (xenogeneic) or C3H/HeN mouse (syngeneic) into the left thighs of six male C3H/HeN mice. The SPIO-labeled macrophage was administered through the tail vein 2 days (acute) or 14 days (chronic) after transplantation in each group. The left thighs of the mice were imaged on a 4.7-T MR scanner 24 h after macrophage administration. We evaluated the extent and pattern of the susceptibility effect (macrophage distribution) and compared them in the two groups. The MR findings were then correlated with the histopathologic results. We also measured in both groups the monocyte chemoattractant protein (MCP)-1 level before and 2 days, 2 weeks, and 4 weeks after transplantation. RESULTS: The band-shaped lower signal intensity (SI) zone was noted around the graft in the acute and chronic phases of xenogeneic group and in the acute phase of syngeneic group, but it was not noted in the chronic phase of syngeneic transplantation. The lower SI zone corresponded to the distribution of SPIO-labeled macrophages on histopathological analyses. On histologic examination, the severe inflammation developed around the xenogeneic graft, but only slightly around the syngeneic graft. MCP-1 was elevated 2 days after transplantation in both groups, but then gradually decreased in the syngeneic group; in xenogenic group, the MCP-1 value decreased by week 2 but then increased by week 4. CONCLUSIONS: This study demonstrates that the homing of intravenously administered SPIO-labeled macrophages can be monitored on MR imaging and is correlated with the MCP-1 level and the histopathologic findings of the xenograft rejection.

Neuroprotective effects of growth hormone against hypoxic-ischemic brain injury in neonatal rats: 1H magnetic resonance spectroscopic study.

Using 1H-MRS, we evaluated the effects of growth hormone (GH) as a caspase inhibitor on hypoxic-ischemic injury in neonatal rat brains. The right common carotid arteries of rats were ligated, allowed to recover for 3 hr, and exposed to 8% oxygen for 2 hr. GH was given just prior to HI insult and animals were divided into four groups: control, intracerebroventricular (ICV), intracerebroventricular/intraperitoneal (ICV/IP), and intraperitoneal (IP). Localized in vivo 1H-MRS and TUNEL staining were performed 24 hr after HI injury. Lipid/N-acetyl aspartate (NAA) and lipid/creatine (Cr) ratios were used as apoptotic markers. Gross morphologic changes at 2 weeks were used to evaluate the effects of GH. The lipid/NAA ratio was lower in the ICV and ICV/IP groups than in the control, and the lipid/Cr ratio was lower in the ICV group than in the control. The number of TUNEL positive cells was decreased in the ICV and ICV/IP groups, and the degree of morphologic change indicative of brain injury was lower in the ICV group and somewhat lower in the ICV/IP group. The degree of morphologic change correlated with the lipid/NAA and lipid/Cr ratios. These findings suggest that GH exerts neuroprotective effects in cerebral hypoxic-ischemic injury.

MR imaging of in vivo recruitment of iron oxide-labeled macrophages in experimentally induced soft-tissue infection in mice.

PURPOSE: To evaluate the feasibility of magnetic resonance (MR) imaging in depicting in vivo recruitment of iron oxide-labeled macrophages in experimentally induced soft-tissue infection. MATERIALS AND METHODS: The study was performed according to the guidelines of the U.S. National Institutes of Health and recommendations of the committee on animal research. The protocol was approved by the local institutional review committee on animal care. Experimental soft-tissue infection in 12 mice was induced by inoculation with a 5 x 10(7) colony-forming units of Staphylococcus aureus into the left calf. Peritoneal macrophages were harvested from thioglycollate-treated mice, cultured, and labeled with iron oxide in vitro. The iron oxide-labeled macrophage (macrophage group, n = 6) or iron oxide solution (control group, n = 6) was administered through the tail vein. The left calf of the mice was imaged on days 2 and 3 with a 4.7-T MR unit. Changes in relative signal intensity (SI) and pattern of contrast material enhancement (macrophage distribution) were analyzed and compared with histopathologic findings. Statistical analysis was performed with the Wilcoxon matched-pairs signed rank test. RESULTS: On MR images obtained 24 hours after administration of macrophage labeled with iron oxide, a band-shaped lower SI zone was noted in the abscess wall, which corresponded to the distribution of the iron oxide-labeled macrophages at histopathologic examination. The relative SI of the abscess wall significantly decreased after injection of iron oxide-labeled macrophages (median, 0.42) compared with that before injection (median, 1.23) (P = .031). In the control group, the SI change after administration of iron oxide solution was not significant (P = .688). CONCLUSION: Homing of intravenously administered iron oxide-labeled macrophages can be monitored with MR imaging and may provide a tool to investigate interactions between macrophages and the invading pathogens.

Effects of heart transplantation on cerebral metabolic abnormalities in patients with congestive heart failure.

We investigated the serial changes in cerebral metabolites in 34 patients with congestive heart failure before and 2 and 12 months after heart transplantation, using proton magnetic resonance spectroscopy. Regional differences were detected in the recovery of cerebral metabolites after the heart transplantation procedure.

Neonatal hypoglycaemic encephalopathy: diffusion-weighted imaging and proton MR spectroscopy.

We report two infants with neonatal hypoglycaemic encephalopathy who were evaluated with diffusion-weighted imaging (DWI) and proton MR spectroscopy (MRS) as well as conventional MR. As in conventional MR, DWI and proton MRS revealed a predominance of abnormalities in the parieto-occipital lobes and underlying white matter including the splenium of the corpus callosum. In the acute phase of the disease, lesions on DWI showed restricted water diffusion and on DWI the characteristic lesions seemed to be more readily discernible than on conventional MRI. In the chronic phase, DWI demonstrated increased water diffusion in the affected areas showing atrophy on conventional MRI. Proton MRS revealed an increased lactate-lipid peak and a decreased NAA peak in the involved areas. DWI and proton MRS findings appear helpful in evaluating the extent and the presence of neuronal damage early in the course of neonatal hypoglycaemic encephalopathy.

Localized 1H-MR spectroscopy in moyamoya disease before and after revascularization surgery.

OBJECTIVE: To evaluate, using localized proton magnetic resonance spectroscopy ((1)H-MRS), the cerebral metabolic change apparent after revascularization surgery in patients with moyamoya disease. MATERIALS AND METHODS: Sixteen children with moyamoya disease and eight age-matched normal controls underwent MR imaging, MR angiography, conventional angiography, and (99m)Tc- ECD SPECT. Frontal white matter and the basal ganglia of both hemispheres were subjected to localized (1)H-MRS, and after revascularization surgery, four patients underwent follow-up (1)H-MRS. RESULTS: Decreased NAA/Cr ratios (1.35+/-0.14 in patients vs. 1.55+/-0.24 in controls) and Cho/Cr ratios (0.96+/-0.13 in patients vs. 1.10+/-0.11 in controls) were observed in frontal white matter. After revascularization surgery, NAA/Cr and Cho/Cr ratios in this region increased. In the basal ganglia, there is no abnormal metabolic ratios. CONCLUSION: Localized (1)H-MRS revealed abnormal metabolic change in both hemispheres of children with moyamoya disease. Because of its non-invasive nature, (1)H-MRS is potentially useful for the preoperative evaluation of metabolic abnormalities and their postoperative monitoring.