Presence of alternative 5' untranslated sequences and identification of cells expressing ctk transcripts in the brain and testis

From a mouse brain cDNA library, two species of the Csk-type tyrosine kinase (ctk) gene containing different 5' untranslated sequences were cloned. Using the common as well as specific nucleotide sequences of the two clones as probes, we examined the expression of ctk in various mouse tissues by Northern blot analysis. The results indicated that both species of ctk were expressed in the brain, testis and bone marrow. By in situ histochemistry of the brain, ctk transcript was detected in neurons throughout the entire brain, especially those of the cortex, the hippocampus and the cerebellum. This distribution pattern is similar to that of the Src family kinases including Yes, Src, Fyn and Lyn. In the testis, the major transcript (0.7 kb) was shorter than that expressed in the brain and the bone marrow (2.0 kb). A subsequent Northern blot analysis of fractionated germ cell populations and in situ histochemistry revealed that the short and long transcripts were expressed in germ cells and somatic cells, respectively, and that the expression level was quantitatively regulated during germ cell development. These results suggest that Ctk is involved in the regulation of neural function and differentiation of male germ cells through interactions with member(s) of the Src family kinases.

[Cerebral blood flow and metabolism in Lafora disease]

An 18-year-old male manifesting intellectual deterioration and negative myoclonus was diagnosed as Lafora disease by the demonstration of Lafora bodies in the skin and muscle biopsy. The cortical evoked potential to electric stimulation of the median nerve at wrist showed the giant SEP, suggesting hyperexcitability of the sensory motor cortex. Cerebral blood flow, and cerebral glucose and oxygen metabolism were investigated by positron emission tomography (PET) in order to clarify the pathophysiological process in Lafora disease. The result showed diffusely decreased cortical glucose metabolic rate and cerebral blood flow, and moderately lowered oxygen metabolic rate. There was no increase in blood flow or glucose and oxygen metabolism in the sensorimotor cortex in spite of the presence of giant SEP. The ratio of the glucose to oxygen metabolism was not different from the mean value obtained from nine normal subjects. Based on these findings and review of the literature, it is unlikely that there is a significant deficit in cortical energy metabolism in patients with Lafora disease and it would be less plausible to have some enzymatic deficits in glucose metabolic process.

Induction of CL100 protein tyrosine phosphatase following transient forebrain ischemia in the rat brain

Protein tyrosine phosphorylation is thought to play an important role in the regulation of neural function. To elucidate the role that protein tyrosine phosphatases (PTPs) may play in the postischemic brain, PTPs expressed in regions of the rat brain vulnerable to transient forebrain ischemia were examined. With the reverse-transcriptase polymerase chain reaction using degenerate primers, three PTPs, STEP, PTP delta, and SH-PTP2, were identified. They were expressed in the hippocampus 12 h after transient ischemia for 20 min. During the reperfusion period, the mRNA levels of these PTPs were not different from those in sham-operated rats. In contrast, a fourfold increase in the mRNA level of CL100 (3CH134), a PTP that is inducible by oxidative stress, was detected by Northern blotting in the hippocampus and cerebral cortex 1 h after the onset of reperfusion. In situ hybridization histochemistry showed a slight increase in the level of CL100 mRNA in neuronal cells in the hippocampus and cortex of postischemic rats compared to control rats. These findings suggest that PTPs play a role in the normal function of the hippocampus and cerebral cortex and demonstrate that ischemia induced CL100 expression.

Crossed cerebellar hypoperfusion indicates the degree of uncoupling between blood flow and metabolism in major cerebral arterial occlusion

BACKGROUND AND PURPOSE

In patients who have major cerebral arterial occlusive disease with low perfusion, a decrease in cerebral metabolism may be reflected by a reduction in contralateral cerebellar blood flow (crossed cerebellar hypoperfusion). This study was done to investigate whether comparison of the extent of cerebral blood flow asymmetry and crossed cerebellar hypoperfusion could be used to estimate the degree of uncoupling of cerebral blood flow and metabolism on the basis of a single blood flow study.

METHODS

We used positron emission tomography before and after reconstructive vascular surgery to evaluate regional blood flow and oxygen metabolism in the cerebral and cerebellar cortexes of 11 patients with major cerebral arterial occlusive disease.

RESULTS

Preoperatively these patients had cortical blood flow asymmetry in the middle cerebral artery territory. The degree of crossed cerebellar hypoperfusion had no relation to the extent of cerebral blood flow asymmetry but was significantly correlated with the extent of asymmetry in cerebral oxygen metabolism. The preoperative extent of asymmetry in the cerebral oxygen extraction fraction and the postoperative improvement of asymmetry in cerebral blood flow were correlated with the preoperative difference between the severity of cerebral blood flow asymmetry and crossed cerebellar hypoperfusion.

CONCLUSIONS

The difference between the extent of cerebral blood flow asymmetry and crossed cerebellar hypoperfusion can be used to estimate the degree of uncoupling between blood flow and metabolism, which can in turn predict the postoperative improvement of cerebral blood flow asymmetry. We suggest that this approach may be a simple means of estimating the relative uncoupling between blood flow and metabolism from a single blood flow study in patients who have major cerebral arterial occlusive disease with low perfusion.

Callosal atrophy in patients with lacunar infarction and extensive leukoaraiosis. An indicator of cognitive impairment

BACKGROUND AND PURPOSE

It is unclear why only some patients with lacunar infarction and radiological evidence of diffuse white matter abnormalities have dementia. The purpose of this study is to investigate the value of callosal atrophy as an indicator of cognitive impairment.

METHODS

We used magnetic resonance imaging to evaluate 11 right-handed male patients with lacunar infarction and extensive white matter hypodensities on computed tomography (8 with dementia and 3 without dementia). The midsagittal corpus callosum area on T1-weighted images was compared with the IQ determined by the Wechsler Adult Intelligence Scale. The relation between these parameters and cerebral oxygen metabolism measured with positron emission tomography was also evaluated in the 8 patients with dementia.

RESULTS

All patients showed diffuse high-intensity areas in the bilateral hemispheric white matter on T2-weighted images. Compared with 19 age- and sex-matched right-handed normal control subjects, the patients had a significantly smaller callosal area. The severity of callosal atrophy, which varied from mild to severe, was significantly related to the total IQ. In the 8 demented patients, the total callosal area was significantly correlated with the mean level of oxygen metabolism in the cerebral white matter.

CONCLUSIONS

In patients with lacunar infarction and diffuse white matter abnormalities, the presence of callosal atrophy may indicate cognitive impairment. Callosal atrophy may reflect the severity and extent of white matter damage associated with a decrease in oxygen metabolism, which may determine the severity of intellectual decline.

Olivopontocerebellar atrophy studied by positron emission tomography and magnetic resonance imaging

We examined 9 patients with olivopontocerebellar atrophy (OPCA) using positron emission tomography and magnetic resonance imaging (MRI). Regional cerebral blood flow and oxygen metabolism were compared with the findings in 10 normal age-matched volunteers. The volumes of the basis pontis and the cerebellar hemispheres were quantitated by MRI to assess the relationship between morphological changes of the pons or cerebellum and the cerebellar circulation and metabolism. In the patients with OPCA, cerebellar hemispheric blood flow and oxygen metabolism were significantly lower than in the normal volunteers. Pontine volume showed a significant correlation with the cerebellar blood flow and the metabolic rate of oxygen. In contrast, the cerebellar hemispheric volume showed no correlation with either of these parameters. Our results suggest that the disruption of pontocerebellar pathway may contribute to the reduction of both blood flow and oxygen metabolism in the cerebellum of OPCA and that detection of cerebellar circulatory impairment without marked cerebellar atrophy by neuroimaging may be suggestive of OPCA.

Scopolamine abolishes cerebral blood flow response to somatosensory stimulation in anesthetized cats: PET study

The effect of the cholinergic blocker, scopolamine on the cerebral blood flow (CBF) response to vibrotactile stimulation of a fore paw was studied using high-resolution positron emission tomography and H2 15O in 5 pentobarbital-anesthetized cats. Before scopolamine injection, the CBF response to the stimulation was found in the contralateral somatosensory cortex (mean ratio (contralateral/ipsilateral) control: stimulated 1.02 +/- 0.02: 1.17 +/- 0.05; P < 0.01). After intravenous injection of scopolamine (0.35 mg/kg), the CBF response was abolished. However, the cerebral metabolic rate of glucose (CMRGlu) response to the same stimulation was unchanged after scopolamine injection in the same cats. We concluded that scopolamine abolishes the CBF response but not neuronal response to stimulation. We suggest that cholinergic mechanisms may play an important role for mediating CBF coupling to neuronal activity during physiological stimulation.

Epidural venous system (meningorachidian venous plexus) in juvenile amyotrophy of distal upper extremity: assessment with GD-DTPA enhanced volumetric MR study

The epidural venous system (meningorachidian venous plexus) was analyzed utilizing gadolinium-diethylenetriamine pentaacetic acid (DTPA) (Gd-DTPA) enhanced volumetric magnetic resonance (MR) images in 11 patients with focal cervical spinal cord atrophy, clinically consistent with juvenile amyotrophy of distal upper extremity. In our series, all of the patients showed unusual posterior epidural venous enhancement at the C5-6 level, suggesting posterior epidural venous dilatation. Three patients also showed prominent dilatation of cervico-thoracic epidural veins surrounding the thecal sac. These MR findings were also demonstrated by spinal phlebography. Gd-DTPA enhanced MR images, especially high resolutional volumetric MR images, were efficient for evaluating these vessels. The observation of meningorachidian venous plexus along the disease course should be necessary for searching the pathogenesis of this disease.

Impaired stereoacuity due to a lesion in the left pulvinar

A right-handed patient with a haematoma in the left pulvinar showed impaired stereoacuity. In contrast with previous reports, he did not show peripheral visual extinction or prolonged reaction times for targets on the side contralateral to the lesion.

Dissociation between contingent negative variation and Bereitschaftspotential in a patient with cerebellar efferent lesion

Contingent negative variation (CNV) and Bereitschaftspotential (BP) were from the scalp in a patient with a discrete infarct in the mesial tegmentum of the midbrain involving the decussation of the superior cerebellar peduncle. Bereitschaftspotential in association with hand movements was completely absent while CNV was normally present at the frontocentral midline. This indicates that CNV is, as opposed to BP, generated without cerebro-cerebellar interactivation, suggesting different generating mechanisms.

Altered cerebral energy metabolism in Alzheimer's disease: a PET study

In an effort to better understand the metabolic basis for the reported decreases in regional cerebral cortex glucose metabolism in patients with Alzheimer's disease, glucose utilization oxygen consumption and regional cerebral blood flow were examined.

METHODS

Nine patients with Alzheimer's disease and nine age-matched normal controls were imaged using 18F-labeled deoxyglucose and 15O-labeled gases.

RESULTS

Regional analysis of the cerebral metabolic rate of glucose (CMRglu), cerebral metabolic rate of oxygen (CMRO2) and cerebral blood flow (CBF) revealed that these values were significantly low in the frontal, parietal and temporal regions. The parietotemporal region had an abnormally high metabolic ratio (CMRO2/CMRglu), while the frontal, sensorimotor and occipital visual cortices had a metabolic ratio similar to that of the normal controls.

CONCLUSIONS

These findings suggest that the abnormal parietotemporal metabolism in Alzheimer's disease involves a metabolic shift from glycolytic to oxidative metabolism. This impairment of glucose degradation may be the basis for synoptic dysfunction underlying the impairment observed in Alzheimer's disease.

[Altered energy metabolism in Alzheimer's disease]

To evaluate the energy metabolic status of Alzheimer's disease, we examined the cerebral arteriovenous differences of glucose, oxygen, lactate, pyruvate, ketone bodies, and free fatty acids and N-isopropyl-p-(123I) iodoamphetamine (IMP) single-photon emission computed tomography in 5 patients with Alzheimer's disease (4 male and 1 female patients; mean age of 64.80 +/- 8.47 years). Compared with 5 age matched normal control subjects (4 males and 1 female; mean age of 63.20 +/- 10.76 years), the patients showed significantly decreased regional cerebral blood flow only in the parietotemporal region. The global cerebral glucose metabolic rate (CMRGlu) had significantly low value, whereas the global cerebral oxygen metabolic rate (CMRO2) was not changed. The metabolic ratio (CMRO2/CMRGlu) was significantly elevated to 9.73 in the patients with Alzheimer's disease, compared with 5.50 in the normal controls. The cerebral metabolic rates of ketone bodies and free fatty acids were unchanged. The cerebral pyruvate output was significantly decreased. The cerebral lactate output became negative, but the decrease did not reach statistical significance. We concluded that the markedly elevated metabolic ratio suggests an altered energy metabolism in Alzheimer's disease.

Regional cerebral blood flow in catatonic schizophrenia

Single photon emission computed tomography (SPECT) with 123I-iodoamphetamine (IMP) as tracer was used to study regional cerebral blood flow (rCBF) distribution in six patients with the catatonic subtype of schizophrenia (DSM-III-R). IMP-SPECT imaging revealed a significant reduction of rCBF in the parietal lobes of both hemispheres. Three-dimensional reconstruction of the SPECT images identified the superior region of the frontoparietal lobe as the most severely affected region. The pattern of rCBF deficits observed in catatonic schizophrenia differs markedly from that seen in 13 patients with other subtypes of schizophrenia and 7 normal control subjects. These observations indicate that parietal lobe dysfunction may be an important component in the pathology of the catatonic subtype of schizophrenia.

Functional brain imaging of a catatonic type of schizophrenia: PET and SPECT studies

A brain imaging study was conducted in the case of a catatonic type of schizophrenia (DSM-IIIR) by applying (i) positron emission tomography (PET) and (ii) single photon emission computed tomography (SPECT). A PET study using [18F]-2-fluoro-2-deoxy-D-glucose revealed a lower glucose utilization in the dorsal frontal and parietal lobes of both cerebral hemispheres. Correlative SPECT studies using [123I]-iodoamphetamine showed a diminished regional cerebral blood flow in similar regions of the cerebral hemisphere. A three-dimensional volume rendering method of the SPECT images (TITAN) identified the dorsal region of the fronto-parietal lobe as the most severely affected region. These patterns of deficits implicated the role of the dorsal frontal and parietal lobes in the pathogenesis of catatonic syndromes.

Hemodilution improves cerebral hemodynamics in internal carotid artery occlusion

BACKGROUND AND PURPOSE

Hemodilution may be a useful form of therapy for patients with carotid occlusive disease and hemodynamic ischemia. Accordingly, we evaluated the effects of hemodilution on cerebral hemodynamics and oxygen metabolism in patients with carotid artery occlusion.

METHODS

Using positron emission tomography, we analyzed regional cerebral blood flow, oxygen extraction fraction, oxygen metabolic rate, and blood volume before and after isovolemic hemodilution in five patients with unilateral internal carotid artery occlusion and minor stroke. Hemodilution was accomplished by phlebotomy of 400 mL and infusion of 400 mL of hydroxyethyl starch.

RESULTS

Before hemodilution, the patients had a significant decrease in blood flow and oxygen transport along with significantly elevated oxygen extraction fraction in the cerebral hemisphere with carotid artery occlusion compared with six control subjects. After hemodilution, the hematocrit and arterial oxygen content decreased from 41.2% and 18.6 mL/dL to 36.3% and 16.5 mL/dL, respectively. Both cerebral blood flow and oxygen transport were increased and oxygen extraction fraction was decreased without any change in oxygen consumption. The degree of increase in blood flow and oxygen transport was positively correlated with the ratio of oxygen extraction fraction to blood volume before hemodilution.

CONCLUSIONS

These findings indicate that hemodilution improves oxygen transport as well as blood flow in patients with internal carotid occlusion and decreased perfusion and that this improvement may be more prominent in patients with a severely compromised hemodynamic state. Thus, hemodilution may be useful in patients with hemodynamic ischemia.

Response of post-ischemic myocardium to sympathetic stimulation--relation to local norepinephrine release

Myocardial ischemia interrupts neurotransmission and causes the depression of norepinephrine release. However, the effects of sympathetic nerve stimulation on neurotransmission and norepinephrine release in post-ischemic myocardium are not well defined. We measured regional myocardial length and norepinephrine (NE) release during sympathetic nerve stimulation in anesthetized dogs. Dogs were divided into 2 groups: Group 1 (n = 14); sympathetic nerve stimulation, Group 2 (n = 9); pre-treatment with alpha-blockade yohimbine hydrochloride (0.2 mg/kg) followed by sympathetic nerve stimulation. The left anterior descending artery was occluded for 15 min. Sympathetic nerve stimulation was performed before coronary occlusion and after reperfusion. In group 1, the decrease in systolic shortening in the ischemic region persisted for more than 60 min. Although sympathetic nerve stimulation caused an increase in systolic shortening, it was lower than the pre-ischemic value. NE release from the post-ischemic myocardium remained decreased for 60 min. The decrease in the post-ischemic myocardial response to sympathetic nerve stimulation was associated with diminished NE release. When the cardiac sympathetic nerve was denervated with an epicardial phenol application, NE release decreased even further. In group 2, NE release did not decrease following reperfusion. These results suggest that sympathetic nerve conduction is not completely impaired in post-ischemic myocardium and that pre-synaptic alpha -2 receptors might play an important role in diminished NE release.

Callosal atrophy parallels decreased cortical oxygen metabolism and neuropsychological impairment in Alzheimer's disease

OBJECTIVE

To evaluate the relationship of corpus callosum atrophy to cerebral cortical oxygen metabolism and cognitive function in patients with Alzheimer's disease.

DESIGN

Prospective clinicoradiologic correlation with magnetic resonance imaging and positron emission tomography.

SETTING

A university hospital.

PATIENTS, PARTICIPANTS

Ten right-handed male patients with Alzheimer's disease, aged 46 to 70 years (mean +/- SD 57 +/- 6 years), and 14 age- and sex-matched right-handed control subjects.

MAIN OUTCOME MEASURES

The midsagittal corpus callosum areas (on T1-weighted magnetic resonance images), cerebral metabolic rate of oxygen (measured with positron emission tomography using the oxygen-15 steady-state technique), and the IQs of the Wechsler Adult Intelligence Scale.

RESULTS

Compared with control subjects, the patients had significantly decreased callosal areas with a posterior predominance of the degree of atrophy. The area of anterior and posterior halves of the corpus callosum had a significant correlation with the value of oxygen metabolism in the frontal and parietotemporo-occipital association cortices, respectively. The total area of the corpus callosum was significantly related to the total and verbal IQs of the Wechsler Adult Intelligence Scale.

CONCLUSION

Atrophy of corpus callosum reflects the severity and pattern of cortical damage associated with hypometabolism and cognitive impairment in Alzheimer's disease.

Lack of prolonged cerebral blood flow change after transcranial magnetic stimulation

To study the physiological changes in the human brain induced by transcranial magnetic stimulation (TMS), we measured cerebral blood flow (CBF) before and after TMS in 3 healthy volunteers with positron emission tomography (PET). The intersecting point of the figure-of-eight coil was positioned at C3. TMS was delivered 20-32 times at maximum intensity. CBF measured at 50 sec after the termination of TMS showed no significant change in the cerebral cortex corresponding to C3 or any other area. This finding indicates that the hemodynamic change in the brain induced by TMS, if any, lasts only for a short period.