Gd-DTPA has a T₁ shortening effect that enhances the contrast in MRI and is widely used for the clinical evaluation of CNS diseases, though it is not suitable for the detection of cerebral ischemic regions during the superacute stage. Superparamagnetic iron oxide parti-cles have a T₂ shortening effect on relaxation time, reducing signal intensity on T₂-weighted MRI in normal cerebral tissue. From this perspective we tested the feasibility of detecting ischemic lesions during the superacute stage using superparamagnetic iron oxide particles-enhanced MRI.
Male Sprague-Dawley rats were anesthetized using pentobarbital and the left middle cerebral artery was permanently occluded (1t.-PMCAO) using a modified version of the Koizumi method. After 1t.-PMCAO, 100μmoles Fe/kg, 1 ml/kg magnetite, superpar-amagnetic iron oxide particles, (magnetite-injected group, n=9) or physiological saline (vehicle-injected group, n=9) was injected into the femoral vein. T₂-weighted MR images were performed at designated time points immediately after injection of magnetite or vehicle on a 6.34 T MR unit. Additionally, in separate animals coronal sections of the brain were stained with 4 % 2, 3, 5 triphenyl-tetrazolium-chloride (TTC) to confirm the infarct region.
In the magnetite-injected group, a high signal area at the region of It.-MCA was visible within 20 to 30 min following It.-PMCAO, whereas in the vehicle-injected group no high signal ischemic area could be confirmed until 3 h after It.-PMCAO. Infarction was noticed in the TTC staining 3 h following It.-PMCAO.
In this study magnetite injection allowed the detection of ischemia in the occluded MCA area on T₂-weighted MRI during the superacute stage. These results suggest that ischemia during the superacute stage can be evaluated using magnetite enhanced MRI. (J Nippon Med Sch 1998 ; 65 : 201-206)

View full abstract

The purpose of this study was to investigate the functional relation between the thalamus and other cortical regions in patients with thalamic stroke from the view of cerebral blood flow (CBF) and the cerebral metabolic rate of oxygen (CMRO₂) using positron emission tomography (PET). Twenty patients with thalamic stroke (right lesion=8, left lesion=12) and 7 normal controls were studied. Five patients were diagnosed as having thalamic infarction, and 15 (patients were diagnosed) as having thalamic hemorrhage by X-CT and/or MRI scan. Regional cerebral blood flow and cerebral metabolic rate of oxygen were measured by PET using C¹⁵O₂ and ¹⁵O₂ steady state inhalation technique.
In the left thalamic stroke group, CMRO₂ was significantly decreased in the left cingulate, superior frontal, superior temporal, middle temporal, medial occipital, and thalamic regions, compared with the normal control group. In the right thalamic stroke group, CMRO₂ was decreased in the left cingulate, medial occipital, right hippocampal, thalamic, and the bilateral cerebellar regions, compared with the normal control group. In the left thalamic stroke group, CBF was decreased significantly in the left cingulate, middle temporal, hippocampal, thalamic, and right cerebellar regions, compared with the normal control group. In the right thalamic stroke group, CBF was significantly decreased in the right hippocampal, thalamic and left cerebellar regions compared with the normal control group.
These results indicate that CBF and CMRO₂ decrease in some distant regions from thalamic lesions, perhaps due to a disconnection of neuronal fiber. Especially in the left thalamic stroke group, CMRO₂ was decreased in the ipsilateral temporal regions. This result suggests that there are more intimate functional fiber connections between the thalamus and temporal cortex in the left hemisphere than in the right hemisphere. (J Nippon Med Sch 1998; 65 : 207-212)

View full abstract

We assessed the regional cerebral blood flow (rCBF) in 8 patients with subcortical aphasia and 8 patients with subcortical infarction without aphasia using the N-isopropyl-P-[¹²³I]-iodoamphetamine autoradiography (¹²³I-IMP ARG) method. In this study, we evaluated vermis to left cortex ratio of CBF. In cases of Broca's aphasia (N=2), CBF was lower in the posterior frontal regions including Broca's area, and more hypoperfused in the posterior frontal and in the posterior temporal regions, including Wernicke's area of total aphasia (N=2). But, it was not significantly hypoperfused in those regions in the cases of Wernicke's (N=2) and amnestic aphasia (N=2).
In the subcortical aphasia, global CBF in the left cerebarl cortex was lower than taht in the right cerebral cortex. However, in the subcortical infarction group without aphasia there was no difference between CBF in the left cerebral cortex and the right cerebral cortex. We conclude that hypoperfusion in the left cerebral cortex was greater than that in the right cerebral cortex and it was probably due to dysfunction of the left cerebral cortex when subcortical infarction occursed with aphasia. Though some types of aphasia were not relative to the dysfunction of the left cerebral cortex. (J Nippon Med Sch 1998 ; 65: 213-219)

View full abstract

The purpose of this study was to investigate the biomechanical properties of anterior cruciate ligament (ACL) reconstruction using an absorbable artificial material in rabbits.
Experimental studies were carried out on 58 New Zealand white rabbits.
After total resection of ACL, 22 knees were reconstructed with patella tendons alone (non-augmented group) and 27 knees with patella tendons augmented by polyglactin 910 mesh (augmented group). The animals were sacrificed for biomechanical testing at 0, 2, 4, 6, 8, 12 and 24 weeks, respectively, after the operation .
The stiffness of reconstructed ACL in the augmented group showed a mean of 26.58±5.78N/mm at 8 weeks, and that of the non-augmented group 16.47±11.34N/mm. There were significant differences between the augmented and non-augmented groups (p<0.05).
The ultimate load and energy of the reconstructed ACL were also significantly higher in the augmented group than in the non-augmented group at 8 weeks.
The mean elastic module was higher in the augmented than in the non-augmented group, but the differences were not significant.
The mean tan δ of both groups was significantly higher than that of the normal ACL at 24 weeks.
These results suggests that polyglactin 910 mesh induces earlier maturation of trans-planted patella tendons biomechanically, and may be a useful material for ACL reconstruction. (J Nippon Med Sch 1998 ; 65 : 220-226)

View full abstract

The pleura is not only a mechanical envelope for the lung but also represents a crossroad for the exchange of cells and fluids. We studied ultrastructural differences in the visceral pleura of male mice in a young age group (aged 1 day, 1 week (wk), 2 wks) and an old age group (10 months (mos), 16 mos, 18 mos, 28 mos, and 30 mos), by both scanning and transmission electron microscopy. Surface microvilli (SMV) of mesothelial cells appeared to be sparse at day 1, then gradually increased in density and reached a plateau at approximately 10 mos. The length of the SMV changed in parallel with density which was confirmed by a morphometric study. After 28 mos, the SMV was partially loose, with an irregular and thin appearance. The morphological properties of pleural connective tissues, including collagen, elastin, and fibroblasts, changed in morphology with the changes in mesothelial cells ; the elastic layer beneath mesothelial cells formed at 2wks and was maintained until 28 mos ; collagen bundles increased in volume density throughout life, whereas cellular components including mesothelial cells, fibroblasts, and alveolar epithelial cells became atrophic with aging. From these observations, we concluded that although SMV do not have any known functions in the pleura, they change with age in a manner that likely corresponds to the changes in pleural connective tissue as well as structural changes in lung parenchyma. (J Nippon Med Sch 1998 ; 65 : 227-235)

View full abstract

With the recent development of measurement in intact PTH, increases of hypoparathyroidism and adynamic bone disease have been reported in patients on chronic maintenance dialysis. To clarify the frequency of hypoparathyroidism in maintenance dialysis patients, the present study investigates the relationship between the occurrence of hypoparathyroidism and clinical background, several bone metabolic markers and the bone mineral density.
We divided 298 maintenance dialysis patients (HD 270, CAPD 28) without parathyroidectomy into 4 groups based on intact PTH. Group A was absolutely hypo (intact PTH<60pg/ml), group B was relatively hypo (60≤intact PTH<160), group C was normal (160≤intact PTH<300), and group D was hyperparathyroidic (300≤intact PTH). Groups A and B together accounted for 71.8% of the patients. The mean age in groups A and B was higher than in group D (p<0.05), and the dialysis duration was shorter (p<0.01). The concentration of 1, 25 (OH)2D was significantly higher in groups A and B than in group D (p<0.01), and remarkably higher in group A than in group C. The level of Ca, i-P did not differ among the groups.
In our investigation of bone metabolic markers, group D was found to have significantly higher Al-p, intact-BGP, and P1PC compared with the other 3 groups (p<0.01), and the concentration of intact BGP was lower in group A than in groups B and C (p<0.01). The bone mineral density measured by DEXA did not differ among the groups.
The results suggest that, due to multiple factors, the actual occurrence of hypoparathyroidism in maintenance dialysis patients is higher than the predicted occurrence. (J Nippon Med Sch 1998 ; 65 : 236-240)

View full abstract