Frontal lobe hypometabolism and depression in Alzheimer's disease

Depression is common in Alzheimer's disease (AD). Clinicoanatomic studies in focal brain injuries and functional imaging studies both in primary depression and in depression secondary to neurologic diseases have demonstrated involvement of the frontal lobe. Frontal involvement has not been established in the depression of AD. We studied the correlation between focal brain metabolic abnormalities and depression in AD. In 53 patients with probable AD of minimal to moderate disability, we assessed the severity of depression using the Neuropsychiatric Inventory and correlated the depression score with regional cerebral glucose metabolism determined by 18F-fluorodeoxyglucose and PET. Depression was present in 19 patients (36%). The depression score correlated significantly with normalized glucose metabolic rates in the bilateral superior frontal and left anterior cingulate cortices. These results indicated an association between depression and decreased activity in the frontal lobe in AD and support frontal involvement, especially in the left side, in depression, irrespective of disease etiology.

Overexpression of the rhoC gene correlates with progression of ductal adenocarcinoma of the pancreas

It has been reported that the rho genes, which consist of a ras-related small GTPase protein family, regulate cytoskeletal structures and have the potential to transform cultured cells. To investigate the biological relevance of the rho genes in pancreatic carcinogenesis, we examined expressions of the rhoA, B and C genes by polymerase chain reaction after reverse transcription (RT-PCR) in 33 cases of ductal adenocarcinoma of the pancreas. In addition, mutations of the K-ras, rhoA, B and C genes were studied in the same series of tumour tissues to correlate with rho gene expressions. The expression levels of the rhoC gene were significantly higher in tumours than in non-malignant portions (P < 0.001). Metastatic lesions overexpressed the rhoC gene compared with primary tumours (P < 0.05). Carcinoma tissues with perineural invasion and lymph node metastasis exhibited significantly higher expressions of the rhoC gene than tumours without these manifestations (P < 0.001 and P < 0.05 respectively). Overexpression of the rhoC gene significantly correlated with poorer prognosis of patients with pancreatic adenocarcinoma (P < 0.05). In contrast, the expression levels of the rhoA and B genes showed no significant relationship with clinicopathological findings. Mutation was not found either in the rhoA, B or C gene sequences examined. K-ras gene mutation, detected in 27 out of 33 (81.8%) cases, did not affect the expression levels in any of the rho genes. These suggest that elevated expression of the rhoC gene may be involved in the progression of pancreatic carcinoma independent of K-ras gene activation.

[Neuropsychiatric features in Dementia with Lewy bodies and Alzheimer's disease]

BACKGROUND AND PURPOSE

Dementia with Lewy bodies (DLB) is commonly accompanied by neuropsychiatric symptoms. Among them, visual hallucinations are reportedly distinguishing DLB from Alzheimer's disease (AD). However, studies that compared frequency of delusions or depression between in DLB and in AD demonstrated conflicting results. Other neuropsychiatric symptoms including aggression, anxiety, and disinhibition have been rarely explored in DLB. In the present study, in order to elucidate the distinctive neuropsychiatric features in DLB, we analyzed neuropsychiatric symptoms in patients with DLB and with AD using data-based materials.

SUBJECTS AND METHODS

Subjects were 15 DLB patients extracted from the Dementia Data Bank in the Hyogo Institute for Aging Brain and Cognitive Disorders, where clinical information of patients with dementia were prospectively assembled with planed, standardized assessments. Both patients groups did not differ in age, education, and duration of illness. The male proportion was significantly greater in the DLB group compared with the AD group (DLB: Male 8, Female 7; AD: Male 27, Female 124, p = 0.008). Patients' neuropsychiatric symptoms were assessed with the Neuropsychiatric Inventory during an interview with a caregiver familiar to the patient's everyday behavior. The Mini-Mental State Examination (MMSE) was used for assessing severity of cognitive impairment.

RESULTS

The DLB group had significantly lower MMSE scores compared with AD group (DLB: 16.2 +/- 5.6, AD: 19.3 +/- 4.4, p = 0.013). None of neuropsychiatric symptoms, however, showed a significant relationship with MMSE scores in the DLB group. Hallucination were present in eight (53.3%) of the DLB group. Visual hallucinations were present in seven patients, and both visual and auditory hallucinations in one patient. The frequency of hallucinations (p < 0.0001) and that of visual hallucinations (p < 0.0001) were significantly greater in the DLB group than in the AD group. There was no significant difference in the frequency of auditory hallucinations. Delusions were present in 11 (73.3%) of the DLB group. Misidentification delusions were present in 11 patients, and persecutory delusions were coexisted in 8 patients. The frequency of delusions and that of persecutory delusions in the DLB group did not significantly differ from the AD group. However, the frequency of misidentification delusions was significantly greater in the DLB group than in the AD group (p < 0.0001). No significant difference was noted in the frequency of other neuropsychiatric symptoms.

CONCLUSIONS

Hallucinations, especially visual hallucinations, and misidentification delusions are helpful diagnostic features of DLB in differentiating from AD.

[Preventive measures against hepatitis B virus infection in nursing schools in Japan]

To clarify the use of preventive measures against Hepatitis B Virus infection among nursing students, questionnaires were mailed to 488 nursing schools throughout Japan (including colleges and junior colleges). Two hundred and sixty-eight nursing schools answered our questionnaire. The results are summarized as follows: 1. Eighty percent of the nursing schools that responded, regularly perform the HBs antigen test, and 70% conduct the HBs antibody test. However, only 29% carry out HB vaccinations. 2. Of the 172 schools (71%) that do not actually perform HB vaccinations, only 4% have a HB vaccination plan for the future. 3. The main reasons why the schools do not carry out HB vaccinations are: 1) high cost (48%), 2) low risk of HBV infection among students (34%), 3) the students are thought to be themselves capable of preventing HBV infection (31%). 4. Eighty percent of the nursing schools conduct an orientation program for their nursing students on how to prevent infection before their practical training at school as well as during their practical training at the hospital. 5. Thirty-five percent of the nursing schools have their own "Prevention of HBV Infection Manual", while some of the others use a manual provided by their training hospital. 6. In answer to the question "Do the instructors ask the students to report any potential risk of infection they encounter during their training in the hospital?", 88 approximately 89% of the schools said that they instruct their students to report all injuries involving a needle stick. Other questions relative to various circumstances were also asked. To the question of whether the school requires the students to report any wounds to their fingers or hands, the rate of "yes" answers was only 33%, although this information is essential to prevent avoidable risk. Conclusion In our investigation we found that the HBs antigen and the HBs antibody tests are both performed in a high proportion in nursing schools. Orientation concerning students' training at the hospital to prevent infection is also provided at a high rate. On the other hand, HB vaccinations are not widely performed. Manuals on the prevention of HBV infection are not used at a high proportion either. Also, the reporting system for students encountering any potential risks of infection is insufficient. We think that a more active prevention system for HBV infection should be organized in every nursing school.

Acetylcholine reactivates latent pseudorabies virus in mice

The latency model of pseudorabies virus (PrV) wild strain, YS-81, in mice was established and latent PrV reactivated with acetylcholine. The latent PrV was reactivated from the trigeminal ganglia with acetylcholine. It was found that this model is useful in investigating the mechanism of latent PrV reactivation by acetylcholine.

Adrenomedullin: a possible autocrine or paracrine inhibitor of hypertrophy of cardiomyocytes

Adrenomedullin (AM), a potent vasodilator peptide, exists in the cardiac ventricle; however, the role of AM in the ventricular tissue remains unknown. In the present study, we investigated the production and secretion of AM in cultured neonatal rat cardiomyocytes, and we examined the effect of AM on de novo protein synthesis in these cells by measuring [14C]phenylalanine incorporation. The cardiomyocytes cultured with serum-free media secreted AM into the media in a time-dependent manner at the rate of 12.2+/-0.5 fmol/10(5) cells/48 hours (mean+/-SEM). Angiotensin II (1 micromol/L) or 10% fetal bovine serum significantly (P<.01) increased the AM secretion by 115% and 305%, respectively. In addition, Northern blot analysis of total RNA extracted from the myocytes disclosed the expression of prepro-AM mRNA of 1.6 kb. Synthetic AM at 1 micromol/L significantly reduced the 10(-6) mol/L angiotensin II- and 10% fetal bovine serum-stimulated [14C]phenylalanine incorporation into the cells, by 16% (P<.05) and 20% (P<.01), respectively. The inhibitory effect of AM on the angiotensin II-stimulated [14C]phenylalanine incorporation was abolished dose-dependently by a calcitonin gene-related peptide receptor antagonist, CGRP(8-37). Furthermore, blockade of the action of endogenous AM by either 10(-6) mol/L CGRP(8-37) or anti-AM monoclonal antibody significantly enhanced the basal and 10(-6) mol/L angiotensin II-stimulated [14C]phenylalanine incorporation. In summary, cultured neonatal rat cardiomyocytes produce and secrete AM, and the secreted AM inhibits the protein synthesis of these cells. Thus, AM may act on cardiomyocytes as an autocrine or a paracrine factor modulating the cardiac growth.

Immunohistochemical studies of proliferating cell nuclear antigen and cathepsin D in transitional cell carcinoma of the urinary bladder

Immunohistochemical staining for proliferating cell nuclear antigen (PCNA) and cathepsin D was performed on 60 transitional cell carcinoma (TCC) specimens from 60 patients with bladder cancer. The percentage of PCNA-positive cells (PCNA-labelling index) was determined by counting 500 or 1,000 cells, and cathepsin D expression was graded according to the extent of immunoreactivity to anti-cathepsin D antibody. The PCNA-labelling index was significantly higher in high-grade and high-stage tumors compared to that in low-grade and low-stage tumors. Cathepsin D was highly positive in grade-1 tumors. In contrast, 82% of grade-3 tumors and 76% of advanced tumors showed negative or low reactivity to anti-cathepsin D. Groups of high PCNA-labelling index and negative cathepsin D had significantly poorer prognoses compared to those of the low PCNA group and cathepsin D highly positive group, respectively, in univariate analyses. However, neither of these two factors were independent prognostic factors in multivariate analyses. These results suggest that the PCNA-labelling index and cathepsin D expression may indicate the malignant potential of TCC and may be able to provide additional information for predicting survival when stratifying for grade of bladder cancer.

Induction of rat hepatic cytochrome P450 2B subfamily by azidophenobarbital, as a possible photoaffinity probe for the putative phenobarbital receptor: comparative study with modified phenobarbitals with different functional groups

To study the specific target to which phenobarbital (PB) binds, resulting in the induction of cytochrome P450, we prepared two azido-PBs (AZPBs) as photoaffinity ligands. The azido substituent was introduced at the para- or meta-position of the PB aromatic ring. In this study, we estimated the utility of these compounds by examining their inducing activities in vivo in rats. Induction was assessed by immunoblotting with anti-CYP2B1/2 antibody and measuring testosterone-metabolizing activity, using hepatic microsomes. Administration of p-AZPB to rats increased hepatic CYP2B1/2 protein and testosterone 16beta-hydroxylase activity, although the effects were less than those of unmodified PB. m-AZPB showed no effect in the induction of CYP2B1/2. To assess the specificity of the effects of substituents, we compared the inducing activities of p/m-nitro-PBs, p/m-amino-PBs, and p/m-hydroxy-PBs with those of AZPBs. The results showed that p-nitro-PB, m-amino-PB, and p-hydroxy-PB were also potent inducers for CYP2B1/2, with lower activity than that of unmodified PB, whereas the other three isomers had no effect. These results suggest that 1) the absence of any substituents on the aromatic ring of PB is needed for maximal inducing activity and 2) substitution at the meta-position of the PB aromatic ring tends to reduce effectiveness as an inducer more than does substitution at the para-position. Because p-amino-PB and p-acetylamino-PB, the minor and major metabolites of p-AZPB, respectively, were without effect in the induction of CYP2B1/2, the effect of p-AZPB was considered to be due to the unchanged compound itself. The present study demonstrates that, based on the weak but positive ability to induce CYP2B1/2, p-AZPB may be a useful tool for identifying the putative PB receptor.

Plasma concentrations of antipsychotic drugs in psychiatric inpatients

In current psychiatric therapy, two or more kinds of antipsychotic drugs are usually prescribed in Japan. However, there are few data on the therapeutic plasma concentrations of antipsychotic drugs or on the correlation between the daily dose and the plasma concentration, in cases where several antipsychotic drugs had been prescribed for each patient. We measured the therapeutic plasma concentrations of 9 antipsychotic drugs in 24 psychiatric inpatients during a 6-month period. They were treated with fixed dosages of antipsychotic drugs. Plasma samples were collected early in the morning once a month, and the concentrations of antipsychotic drugs were determined by gas chromatography with nitrogen phosphorus detection, high-performance liquid chromatography (HPLC) with fluorescence detection and HPLC with UV detection. The plasma levels of chlorpromazine, levomepromazine, thioridazine, haloperidol, bromperidol, zotepine, oxypertine, sulpiride and sultopride were 21.8-92.4, 31.7-156, 101-203, 16.4-56.2, 2.72-11.7, 13.6-84.0, 29.9-80.4, 70.1-1,120 and 35.7-2,990 ng/ml, respectively. A linear correlation between the daily dose and the plasma concentration was noted for sultopride, levomepromazine, sulpiride, haloperidol, chlorpromazine and zotepine.

Distribution of drugs in various tissues in a brain dead man

We examined the distribution of drugs in a 49-year-old brain-dead man. Our objective was to determine the possibility of diagnosing how and at what point the patient became brain dead. The presence of mepivacaine, pentazocine, lidocaine and thiamylal in various tissues, including seven regions of the brain were confirmed, using gas chromatography/mass spectrometry. Tissue-to-blood concentration ratios of mepivacaine, pentazocine and lidocaine in the brain were higher than these ratios in other tissues, while ratios of thiamylal were lower. Therefore, cerebral blood flow was likely to have ceased between the administration of the former drugs and that of the latter drug, in agreement with clinical records. Among seven regions of the brain, the ratios of the former three drugs were high in occipital and parietal lobes, and were low in the cerebellum and medulla oblongata. On the other hand, the ratios of the latter drug were high in the cerebellum and the medulla oblongata. Therefore, cerebral blood flow presumably ceased first in occipital and parietal lobes, and last in the cerebellum and the medulla oblongata. Based on these results, assessment of concentrations of drugs in human tissues, including various regions of brain is useful to determine the time and progression of brain death.

Orthotopic ossification of the spinal ligaments of Zucker fatty rats: a possible animal model for ossification of the human posterior longitudinal ligament

Ossification of the posterior longitudinal ligament is a human genetic disease in which pathological ectopic ossification of the spinal ligaments develops. This leads to myelopathy or radiculopathy due to compression of the spinal cord. In this study, we investigated the histological features of orthotopic ossification of the spinal ligaments of senile Zucker fatty rats. A remarkably high incidence of orthotopic ossification was observed mainly in the thoracic spinal ligaments as compared with controls. The histopathological findings were similar to those for ossification of the human posterior longitudinal ligament. Bone morphogenetic proteins and activins, which exert their effects by way of specific type-I and type-II serine/threonine kinase receptors, play important roles in the formation of bone and cartilage. In the spinal ligaments of Zucker fatty rats, bone morphogenetic protein receptors and activin receptors were immunohistochemically detected around the ossified foci in a manner similar to that previously shown for the ossified tissue from patients who had ossification of the posterior longitudinal ligament. Thus, bone morphogenetic proteins and activin receptors might play important roles in orthotopic ossification of the spinal ligaments of Zucker fatty rats as well as in ossification of the posterior longitudinal ligament of humans. In addition, bone morphogenetic protein-receptor-IA was expressed in the nonossified ligament, suggesting that the spinal ligaments, of the rats may have a predisposition to orthotopic ossification. In the controls, no expression of bone morphogenetic protein receptors or of activin receptors was observed. In conclusion, there is a great degree of similarity between orthotopic ossification of the spinal ligaments of Zucker fatty rats and ossification of the posterior longitudinal ligament of humans. Thus, the rats provide a useful animal model for the study of ossification of the human posterior longitudinal ligament.

Evidence for functional roles of Crk-II in insulin and epidermal growth factor signaling in Rat-1 fibroblasts overexpressing insulin receptors

We examined the potential role of Crk-II in insulin and epidermal growth factor (EGF) signaling in Rat-1 fibroblasts overexpressing insulin receptors. Crk is an SH2 and SH3 domain-containing adaptor protein that has been reported to associate with p130cas, paxillin, c-cbl, c-abl, Sos, and C3G in vitro. Insulin- and EGF-induced association of Crk-II with these molecules was assessed by immunoblotting of anti-Crk-II precipitates in Rat-1 fibroblasts overexpressing insulin receptors. Neither insulin nor EGF treatment induced Crk-II association with either Sos or C3G. Basal tyrosine phosphorylation of c-abl and its constitutive association with Crk-II were not further increased by insulin or EGF. p130cas and paxillin were heavily tyrosine phosphorylated in the basal state. Both insulin and EGF stimulated their dephosphorylation, followed by p130cas-Crk-II dissociation and paxillin-Crk-II association, although the magnitude of these effects was greater with insulin than with EGF. Interestingly, EGF, but not insulin, stimulated tyrosine phosphorylation of c-cbl and its association with Crk-II. To investigate the functional roles of Crk-II in mitogenesis and cytoskeletal rearrangement, we performed microinjection analysis. Cellular microinjection of anti-Crk-II antibody inhibited EGF-induced, but not insulin-induced, DNA synthesis. Insulin, but not EGF, stimulated cytoskeletal rearrangement in the cells, and microinjection of anti-Crk-II antibody effectively inhibited insulin-induced membrane ruffling, suggesting that Crk-II is involved in insulin-induced cytoskeletal rearrangement. These results indicate that Crk-II functions as a multifunctional adaptor molecule linking insulin and EGF receptors to their downstream signals. The presence of c-cbl-Crk-II association may partly determine the signal specificities initiated by insulin and EGF.

Regional cerebral glucose metabolism in dementia with Lewy bodies and Alzheimer's disease: a comparative study using positron emission tomography

Regional cerebral metabolic rate of glucose (rCMRglc) was studied in 19 patients with a clinical diagnosis of dementia with Lewy bodies (DLB) and 19 patients with a clinical diagnosis of Alzheimer's disease (AD), using [18F]fluorodeoxyglucose ([18F]FDG) and positron emission tomography (PET). The two groups were matched with age, gender, disease duration and severity of cognitive disturbances. In 'dementia with Lewy bodies' (DLB) patients, when compared with AD patients, significant rCMRglc decreases were distributed in the temporo-parieto-occipital association cortices and the cerebellar hemispheres. In contrast, the medial temporal and cingulate rCMRglc were significantly lower in AD patients than those in DLB patients. These different regional emphases of glucose hypometabolism are consistent with the pathological and neurochemical differences between DLB and AD and explain the different clinical features of the two diseases.

Smad6 inhibits signalling by the TGF-beta superfamily

SMAD proteins have been identified as signalling mediators of the TGF-beta superfamily, which is involved in a range of biological activities including cell growth, morphogenesis, development and immune responses. Smad1, Smad2, Smad3 and Smad5 are ligand-specific: Smadl and Smad5 transduce signals from bone morphogenetic proteins, and Smad2 and Smad3 mediate signalling by TGF-beta and activin, whereas Smad4 acts as a common signalling component. For example, Smad2 is phosphorylated by the TGF-beta type I receptor upon ligand binding, forms a heteromer with Smad4, and then translocates into the nucleus where it activates transcription. Here we report the isolation of Smad6 in the mouse. Smad6 is quite different in structure from the other SMAD proteins, and forms stable associations with type I receptors. Smad6 interferes with the phosphorylation of Smad2 and the subsequent heteromerization with Smad4, but does not inhibit the activity of Smad3. Smad6 also inhibits the phosphorylation of Smad1 that is induced by the bone morphogenetic protein type IB receptor. These data indicate that signals of the TGF-beta superfamily are regulated both positively and negatively by members of the SMAD family.

[Objective evaluation of selective peripheral denervation for spasmodic torticollis]

The authors evaluated the results of selective peripheral denervation (SPD) of posterior rami of the cervical spinal nerves and/or the accessory nerve for spasmodic torticollis. Five patients underwent seven operations in total and the results were evaluated with the modified Tsui's score which was used in the clinical trial of botulinum toxin (BTX) for torticollis in Japan. The preoperative score was 10.8 +/- 2.2 (mean +/- S.D.) and the postoperative score was 1.4 +/- 1.7. The score changes indicated the effects of the operation as "excellent" in four cases and "good" in one case. These results indicate that SPD is superior to BTX in terms of control of symptoms in spasmodic torticollis. After the initial operation, however, two patients showed the so-called "mole-hitting game phenomenon" in which normal muscles develop abnormal contraction after denervation of abnormal muscles. This forced us to perform the second operations. Although this phenomenon was first described in botulinum toxin treatment, this is probably the first report in surgically denervated cases.

Simple and rapid determination of enflurane in human tissues using gas chromatography and gas chromatography-mass spectrometry

A simple, rapid and reliable method was devised to determine the levels of enflurane in human tissues, using gas chromatography and gas chromatography-mass spectrometry. 1,4-Dioxane was used as an internal standard (I.S.). Enflurane and the I.S. were extracted from 0.25 g of body tissues using an automatic headspace sampler and 1 ml of headspace gas was injected into the gas chromatograph. Enflurane was analyzed qualitatively by gas chromatography-mass spectrometry and quantitatively by gas chromatography with a flame-ionization detector. The calibration curves in all tissues examined were linear in the concentration range 1-100 microg/0.25 g. The lower limit of detection was 200-300 ng/0.25 g. The accuracy and precision of this method were evaluated at two different concentrations, 1 and 20 microg/0.25 g. The coefficient of variation ranged from 3.4-13.4%. We used this method to determine the presence of enflurane in tissues from an autopsied individual who died suddenly during extirpation of a malignant tumor.

Detection of triazolam in skeletal remains buried for 4 years

Analyses of the hypnotic triazolam from the remains of two human skeletons buried underground for 4 years were made for purposes of confirmation. The bone marrow and mummified muscle were digested with 2 M sodium hydroxide, efficiently extracted using a 3-step solvent extraction procedure, and selectively analyzed by gas chromatography/mass spectrometry with the negative ion chemical ionization mode. Estazolam was the internal standard used. Triazolam was detected in all the samples; the concentrations were 0.36 ng/g in the bone marrow of one victim, and 0.37 and 5.5 ng/g in the bone marrow and mummified muscle of the other victim. This method should prove useful for determination of triazolam in extensively decomposed bodies.

Molecular cloning of rat leukemia inhibitory factor receptor alpha-chain gene and its expression during pregnancy

Leukemia inhibitory factor (LIF) is a secreted glycoprotein and a pluripotent growth factor that acts on diverse cell systems. LIF transmits its effects via binding to transmembrane receptors, of which both high- and low-affinity forms have been identified. In this study, we analyzed the structure and expression of rat LIF receptor alpha-chain (rLIFR alpha) cDNA. A full-length clone of the cDNA encoding the membrane-bound form of rLIFR alpha protein was prepared by a combination of LA-PCR and 5' RACE using DNA reverse-transcribed from total RNA isolated from the livers of day-12 and day-14 pregnant rats as templates. The nucleotide sequence of a full-length clone was determined and further confirmed by analysis of shorter DNA fragment prepared by PCR using pfu polymerase. The gene for rLIFR alpha encodes a 1093 amino acid residue protein. The rLIFR alpha protein shows a high degree of similarity to mouse and human LIF receptor alpha-chain protein (89% and 76% amino acid sequence identities, respectively). Only one molecular species of mRNA for the rLIFR alpha gene was detected in the liver and placenta. rLIFR alpha was expressed in liver of both non-pregnant and pregnant rats. The level of mRNA for the rLIFR alpha gene in placenta was maximum on day 16 of pregnancy.

TGF-beta receptor-mediated signalling through Smad2, Smad3 and Smad4

Smad family members are newly identified essential intracellular signalling components of the transforming growth factor-beta (TGF-beta) superfamily. Smad2 and Smad3 are structurally highly similar and mediate TGF-beta signals. Smad4 is distantly related to Smads 2 and 3, and forms a heteromeric complex with Smad2 after TGF-beta or activin stimulation. Here we show that Smad2 and Smad3 interacted with the kinase-deficient TGF-beta type I receptor (TbetaR)-I after it was phosphorylated by TbetaR-II kinase. TGF-beta1 induced phosphorylation of Smad2 and Smad3 in Mv1Lu mink lung epithelial cells. Smad4 was found to be constitutively phosphorylated in Mv1Lu cells, the phosphorylation level remaining unchanged upon TGF-beta1 stimulation. Similar results were obtained using HSC4 cells, which are also growth-inhibited by TGF-beta. Smads 2 and 3 interacted with Smad4 after TbetaR activation in transfected COS cells. In addition, we observed TbetaR-activation-dependent interaction between Smad2 and Smad3. Smads 2, 3 and 4 accumulated in the nucleus upon TGF-beta1 treatment in Mv1Lu cells, and showed a synergistic effect in a transcriptional reporter assay using the TGF-beta-inducible plasminogen activator inhibitor-1 promoter. Dominant-negative Smad3 inhibited the transcriptional synergistic response by Smad2 and Smad4. These data suggest that TGF-beta induces heteromeric complexes of Smads 2, 3 and 4, and their concomitant translocation to the nucleus, which is required for efficient TGF-beta signal transduction.

Changes in cerebral blood flow and oxygen metabolism related to magnetic resonance imaging white matter hyperintensities in Alzheimer's disease

We studied changes in cerebral perfusion and oxygen metabolism to elucidate the pathophysiological nature and clinical significance of white matter hyperintensities in Alzheimer's disease (AD).

METHODS

Sixteen AD patients (age 71.6 +/- 3.1 yr) whose T2-weighted MR images showed white matter hyperintensities, and 16 age-matched AD patients (age 71.0 +/- 4.3 yr) without white matter hyperintensities were compared. Regional cerebral blood flow (CBF), oxygen metabolism (CMRO2) and oxygen extraction fraction (OEF) were measured by using (15)O steady-state method and PET.

RESULTS

There was no significant difference in cognitive impairment between the two groups. Compared to the patients without white matter hyperintensities, those with them had significantly low CBF values and significantly high OEF values in all cortical and white matter regions. However, there were no significant differences in CMRO2 values between the two groups. Severity of white matter hyperintensities correlated with the mean cortical and mean white matter OEF.

CONCLUSION

In AD patients, white matter hyperintensities on T2-weighted MR images represent ischemic changes in which oxygen metabolism and function are fairly compensated. These changes are not disease-specific but are age-associated coincidences, as in normal aging with or without vascular risk factors.

Functional importance of heat shock protein 90 associated with insulin receptor on insulin-stimulated mitogenesis

The role of stress proteins on the function of insulin receptor is not well understood. In the rat-1 fibroblasts overexpressing human insulin receptors, heat shock protein (Hsp) 90 was co-immunoprecipitated with insulin receptors and the association was not affected by insulin stimulation. A GST-fusion protein containing the intracellular insulin receptor beta subunit was associated with Hsp 90 in vitro, suggesting the direct interaction of this protein with insulin receptor beta-subunit. Furthermore, microinjection of anti-Hsp 90 antibody into these cells completely inhibited insulin-stimulated mitogenesis. However, neither epidermal growth factor-stimulated nor serum-stimulated mitogenic signal in the cells was affected by the antibody microinjection. These results suggest that Hsp 90 constitutively binds to insulin receptor beta-subunit, which may be necessary for insulin signaling in mitogenesis.

Fatty acid induced insulin resistance in rat-1 fibroblasts overexpressing human insulin receptors: impaired insulin-stimulated mitogen-activated protein kinase activity

Saturated fatty acids cause insulin resistance but the underlying molecular mechanism is still unknown. We examined the effect of saturated nonesterified fatty acids on insulin binding and action in transfected Rat-1 fibroblasts, which over-expressed human insulin receptors. Incubation with 1.0 mmol/l palmitate for 1-4 h did not affect insulin binding, insulin receptor autophosphorylation, insulin-stimulated tyrosine kinase activity toward poly(Glu4:Tyr1), pp185 and Shc phosphorylation and PI3-kinase activity in these cells. However, the dose response curve of insulin-stimulated glucose transport was right-shifted. Palmitate inhibited the maximally insulin-stimulated mitogen activated protein (MAP) kinase activity toward synthetic peptide to 7% that of control. The palmitate treatment influenced neither cytosolic protein kinase A activity nor cAMP levels. These results suggested that 1) palmitate did not inhibit the early steps of insulin action from insulin binding to pp185 or Shc phosphorylation but inhibited insulin-stimulated MAP kinase, and that 2) palmitate decreased insulin sensitivity as manifested by inhibited insulin-stimulated glucose uptake. In conclusion, the mechanism of saturated non-esterified fatty acid induced insulin resistance in glucose uptake may reside at post PI3-kinase or Shc steps, including the level of MAP kinase activation.