Computed TomographyNegative Acute Thalamic Hematoma

A case of acute thalamic hematoma not detected by computed tomography (CT) but unequivocally diagnosed by magnetic resonance imaging (MRI) is presented. A 79-year-old woman presented with acute left hemiparesis. The results of CT obtained on admission as well as on the seventh hospital day were negative for a hematoma. By contrast, serial MRis exhibited chronological changes in the relaxation properties characteristic of acute hematoma in the thalamus . The case illustrates     

Pulmonary histoplasmosis in a Japanese male: Report of a case

(Received for publication on June 23, 1997; accepted on Jan. 6, 1998)     

An immunohistochemical study of copper/zinc superoxide dismutase and manganese superoxide dismutase following focal cerebral ischemia in the rat

We investigated immunohistochemically the localization and changes of copper/zinc superoxide dismutase (CuZn-SOD) and manganese superoxide dismutase (Mn-SOD) in the rat brain following 1 h of middle cerebral artery (MCA) occlusion. In normal brain, immunoreactivity to both SODs was observed in medium-sized neurons in the striatum and in many neurons in the neocortex. Mn-SOD was predominantly stained in cortical interneurons. The immunostaining of both SODs rapidly decreased or disappeared in neurons in the lateral segment of the striatum (ischemic center) 4 h after MCA occlusion, when the neurons were degenerating. Most neurons in the neocortex (ischemic penumbra) decreased their CuZn-SOD immunoreactivity but not Mn-SOD immunoreactivity 4 h after ischemia, when only a few neurons showed histopathological changes. CuZn-SOD immunoreactivity in almost all cortical neurons disappeared 1 day after ischemia, but Mn-SOD immunoreactivity was still preserved in interneurons, when cortical neurons showed typical pathological changes. Some cortical neurons in the boundary zone between normal and infarcted areas showed intense immunostaining to both SODs and glial SOD immunoreactivity appeared after 3 and 7 days. These results suggest that early loss of the scavenging system of free radicals may lead to neuronal damage after ischemic insult, and that induced SODs in the boundary zone between the normal and infarcted areas may act as a defense mechanism against damage.     

Comparison of regional brain volume and glucose metabolism between patients with mild dementia with lewy bodies and those with mild Alzheimer's disease.

The aim of this study was to investigate regional differences between morphologic and functional changes in patients with mild dementia with Lewy bodies (DLB) compared with those with Alzheimer's disease (AD). METHODS: Twenty patients with very mild DLB (mean age, 74.5 y; mean Mini-Mental State Examination [MMSE] score, 24.0), 20 patients with very mild AD (mean age, 74.1 y; mean MMSE score, 24.0), and 20 age- and sex-matched healthy volunteers (normal controls [NC]) underwent both (18)F-FDG PET and 3-dimensional spoiled gradient echo MRI. Fully automatic volumetry of the MRI data was used to obtain whole brain, hippocampal, occipital, and striatal volumes, which were compared with the results of a similar analysis of glucose metabolic data. RESULTS: In DLB patients, volumetric data indicated a significant volume decrease in the striatum, whereas (18)F-FDG PET showed significant glucose metabolic reductions in the temporal, parietal, and frontal areas--including in the occipital lobe--compared with those in the NC group. In contrast, in AD patients, both the hippocampal volume and glucose metabolism were significantly decreased, whereas the occipital volume and metabolism were preserved. CONCLUSION: Comparison of very mild DLB and AD revealed different morphologic and metabolic changes occurring in the medial temporal lobes and the occipital lobe, demonstrating characteristic pathophysiologic differences between these 2 diseases.     

Effect of verapamil on cardiac protein kinase C activity in diabetic rats

We examined the effect of verapamil treatment on cardiac protein kinase C (PKC) activity in streptozocin-induced diabetic rats. Basal cardiac PKC activity in diabetes increased in both cytosolic (by 94%, P < 0.01) and membrane (by 41%, P < 0.05) fractions as compared with that in controls. Subcutaneous administration of 8 mg/kg verapamil twice a day for 8 weeks induced a significant decrease in both cytosolic (by 59%, P < 0.01) and membrane (by 50%, P < 0.01) PKC activity in diabetes as compared with the activity in the non-treated diabetic groups. In contrast, cardiac cytosolic PKC activity in control rats was significantly (P < 0.01) decreased by 41% as compared with that of the non-treated control group without there being any change in membrane PKC activity. Our data demonstrate that verapamil treatment may ameliorate the abnormal activation of cardiac PKC in diabetes.     

Diffusion tensor analysis: principles and applications]

Diffusion tensor analysis represents a versatile yet powerful application of magnetic resonance imaging (MRI). Early applications of diffusion weighted imaging(DWI), especially those related to ischemic brain disease were quickly overshadowed by more advanced applications of DTA, namely, those dealing with anisotropy analysis. Considering the array of possibilities, from neuronal tract tracing to neuronal density imaging, DTA is rapidly becoming an indispensable tool not only in neuroscience but also in clinical investigations of the brain.     

Ruptures of arteriovenous malformations in children associated with trivial head trauma

Three cases of ruptured arteriovenous malformations (AVMs) in childhood associated with trivial head trauma are reported. These patients represented 12.5% of 25 consecutive patients with cerebral AVMs. The patients' ages ranged from 5 to 9 years; the patients were younger than their nontraumatic counterparts. The force of the trauma was presumably received in an anteroposterior or posteroanterior direction in all cases. Hematomas accompanying the AVMs were located in the subcortical area of the parietal or temporal lobe and angiographically their feeding arteries were all from the anterior cerebral artery or middle cerebral artery. The possible mechanisms for the rupture of AVMs after trivial head trauma are discussed.     

Fast in vitro movement of outer hair cells in an external electric field: Effect of digitonin, a membrane permeabilizing agent

Isolated outer hair cells from the organ of Corti show elongation and contraction in response to an externally applied ac electric field as well as to a direct current injection into these cells. This is thought to be the basis of the positive feedback mechanism for fine tuning of the mammalian hearing organ. To test whether the mechanical response depends on the intracellular electric field or on the membrane potential, we used digitonin to shunt the membrane resistance. We observed that the application of digitonin abolished the cellular response of the outer hair cells to an ac external electric field (5–30 Hz). Coinciding with the abolition of the cellular response, the nuclear matrix started to oscillate synchronous to the external field, indicating an appreciable increase of the intracellular electric field. If the intracellular electric field was the regulating factor of the motile response, the initiation of the movement of the nuclear matrix would have been accompanied by an enhancement of the cellular movement. Our observation is therefore consistent with the interpretation that the (local) membrane potential, and not the intracellular electric field, regulates the hair cell movement.     

Noninvasive analysis of aldose reductase activities in rat testis: 3-FDG NMR spectroscopy and imaging

Noninvasive investigation of aldose reductase activities in rat testis was performed using 3-fluoro-3-deoxy-D-glucose (3-FDG) and nuclear magnetic resonance (NMR) spectroscopy/imaging. Quantitative determination of testis aldose reductase activities, expressed as the sorbitol index, showed a value similar to that of brain. Sorbitol imaging demonstrated aldose reductase activities in testis to be confined primarily to the central region of this organ. The 3-FDG ¹⁹F NMR method appears to have clinical potential in the evaluation of testicular function, especially that of spermatogenesis, noninvasively.     

Dynorphin A-(1–13) attenuates basal forebrain-lesion-induced amnesia in rats

The effects of dynorphin A-(1–13), an endogenous κ opioid agonist, on basal forebrain (BF)-lesion-induced amnesia in rats were investigated using step-through-type passive avoidance task. The BF was lesioned by injecting the cholinergic neurotoxin ibotenic acid (6 μg/side). The number of rats achieving the cut-off time (600 s) of step-through latency (STL) in BF-lesioned group significantly decreased as compared with that in sham-operated group. Dynorphin A-(1–13) (0.3 μg) significantly increased the number of rats achieving the cut-off time of STL in BF-lesioned rats. These results suggest that dynorphins play an improving role in the impairment of memory processes in BF-lesioned rats.