The cytoplasmic domain of Alzheimer's amyloid precursor protein is phosphorylated at Thr654, Ser655, and Thr668 in adult rat brain and cultured cells

BACKGROUND

The cytoplasmic domain of the Alzheimer's disease amyloid precursor protein (APP) is phosphorylated in vitro at Thr654 and Ser655, and both in vitro and in intact cells at Thr668 (numbering for APP695 isoform).

MATERIALS AND METHODS

We have developed phosphorylation state-specific antibodies to each of the sites, and we have used these to analyze the phosphorylation of APP in adult rat brain and in cultured cell lines.

RESULTS

We demonstrate that all three sites in APP are phosphorylated in adult rat brain. Phosphorylation at Thr654, Ser655, and Thr668 was also observed in several cultured cell lines. In PC12 cells, phosphorylation at Ser655 was increased more than 10-fold by treatment with okadaic acid, a specific inhibitor of protein phosphatases 1 and 2A, but was not affected by activators of protein kinase C. In HeLa cells, phosphorylation at Thr668 was regulated in a cell cycle-dependent manner with near-stoichiometric phosphorylation being observed at the G2/M phase of the cell cycle. In general, phosphorylation at Ser655 was found to be highest in mature APP isoforms, whereas phosphorylation of Thr668 was highest in immature APP isoforms in cultured cells.

CONCLUSIONS

The results demonstrate that phosphorylation of the cytoplasmic domain of APP occurs at Thr654, Ser655, and Thr668 under physiological conditions. The further characterization of APP phosphorylation using phosphorylation-specific antibodies may help in the elucidation of the biological function of APP.

Regional cerebral blood flow in lacunar infarction

Ten cases of lacunar infarction, 10 cases of nonlacunar cerebral thrombosis, and 8 healthy controls who did not have risk factors of cerebrovascular diseases were studied. Subcortical cystic infarctions with a diameter of less than 1.5 cm were classified as lacunar infarction and the other cerebral thrombosis were classified as nonlacunar cerebral thrombosis. Cerebral blood flow examination by Xenon computed tomography (CT) method was performed within 14 days after the onset of stroke. Stable Xenon was inhaled for 3 minutes and CT scan was taken once before the inhalation, 3 times during the inhalation, and 5 times in the washout phase. Regional blood flows in the infarcted area, around the infarcted area, and in the cerebral cortex and the cerebral white matter where the influence of the infarction was considered to be little were measured before and after intravenous injection of 17 mg/kg acetazolamide. In the lacunar infarction, the blood flow in the cerebral cortex where the influence of the infarction was considered to be little was decreased and the cerebrovascular dilatory reserve capacity in the cerebral cortex and the cerebral white matter was decreased. Arteriolosclerosis is considered to be the basic cause of lacunar infarction.

Effects of sodium ozagrel on hemostatic markers and cerebral blood flow in lacunar infarction

The present study was designed to examine the effects of sodium ozagrel on hemostatic markers and cerebral blood flow in lacunar infarction. Ten cases of lacunar infarction in which sodium ozagrel was given (administered group), 10 cases of lacunar infarction in which sodium ozagrel was not given (nonadministered group), and 10 age-matched controls in which cerebrovascular diseases were absent but risk factors were similar to those of the patients (control group) were studied. Intravenous infusion of 80 mg of sodium ozagrel was done twice a day for 2 weeks. Platelet factor 4, beta-thromboglobulin, and fibrinopeptide A were significantly higher in the administered and nonadministered groups than in the control group at the time of admission. Platelet factor 4, beta-thromboglobulin, fibrinopeptide A, and thromboxane B2 were decreased significantly by the administration of sodium ozagrel. The blood flow in the cerebral cortex was significantly lower in the administered and nonadministered groups than in the control group. The blood flows around the infarcted area, in the cerebral cortex, and in the cerebral white matter were significantly increased by the administration of sodium ozagrel. Sodium ozagrel is considered to decrease platelet aggregation and increase cerebral blood flow by decreasing thromboxane A2, which has a platelet-aggregating and a vasoconstricting action. Sodium ozagrel is considered to be effective in the acute phase of lacunar infarction.

Expression of the protein tyrosine phosphatase beta2 gene in mouse erythroleukemia cells induces terminal erythroid differentiation

We have cloned cDNA for protein tyrosine phosphatase beta2, which had been implicated in erythroid differentiation of mouse erythroleukemia cells. Expression of cDNA constructs, in which beta2 cDNA is placed under the control of mouse metallothionein-I promoter, by ZnCl2 converted a significant portion (20 to 38%) of the cells to erythroid-like cells, which is 25-50% of the erythroid differentiation efficiency observed by conventional erythroid-inducing agents. Furthermore, introduction and expression of altered protein tyrosine phosphatase beta2 cDNA constructs designed to produce the enzyme lacking the phosphatase activity inhibited erythroid differentiation by 100-20%, depending upon the concentration of erythroid-inducing agents employed. These results strongly suggest that protein tyrosine phosphatase beta2 is involved in triggering erythroid differentiation in mouse erythroleukemia cells.

In vitro transcription of a poly(dA) x poly(dT)-containing sequence is inhibited by interaction between the template and its transcripts

Transcription of poly(dA) x poly(dT)-containing sequences was investigated in vitro using plasmids carrying a (dA)34 x (dT)34 tract in the coding region of the lacZ gene. The efficiency of transcription of the (dT)34 sequence on the transcribing strand by Escherichia coli RNA polymerase was substantially lower (approximately 60%) than that of the (dA)34 sequence or of the control lacZ gene. Analysis of the transcription process of the (dT)34 sequence by T3 RNA polymerase showed that the transcription was frequently arrested or terminated at the middle as well as immediately proximal of the (dA)34 x (dT)34 tract, and it occurred more prominently following accumulation of transcription products. This inhibition was strongly enhanced by the addition of the oligonucleotide (dT)34 or poly(U) to the reaction mixture, while (dA)34 and the duplex (dA)34 x (dT)34 suppressed the inhibition. A similar transcriptional inhibition was also observed in transcription mediated by T7 RNA polymerase and eukaryotic RNA polymerase II. We also demonstrated RNA x DNA complex formation of the (dA)34 x (dT)34 tract with poly(U), but not with poly(A). These findings strongly suggest that poly(dT)-containing template sequences interact and form a complex with its transcription products, possibly an RNA x DNA triplex, which blocks further transcription. This would explain the instability of the plasmids transcribing mRNAs with poly(U) but not poly(A) tracts and the underrepresentation of poly(U) but not poly(A) tracts in mRNAs.

Central motor conduction time in patients with periventricular lucencies

Central motor conduction time and regional cerebral blood flow were measured before and 20 min after intravenous injection of 17 mg/kg acetazolamide in 10 patients with periventricular lucencies (PVL) and 10 age-matched healthy controls. Central motor conduction time was measured using a magnetic stimulator and regional cerebral blood flow was measured by stable xenon computed tomography method. The central motor conduction time was significantly longer in the patients with PVL than in the healthy controls and was shortened significantly by the intravenous injection of acetazolamide in the patients with PVL. The blood flow not only in the periventricular white matter but also in the cerebral cortex and the cerebral white matter was significantly lower in the patients with PVL than in the healthy controls. The intravenous injection of acetazolamide increased significantly the regional cerebral blood flow except in the PVL areas. The prolongation of the central motor conduction time may be at least partly related with decreased blood flow in the cerebral cortex and cerebral white matter.

Evaluation of fasudil hydrochloride treatment for wandering symptoms in cerebrovascular dementia with 31P-magnetic resonance spectroscopy and Xe-computed tomography

This is the first report on the evaluation of treatment with fasudil hydrochloride, a novel intracellular calcium antagonist, for wandering symptoms in patients with cerebrovascular dementia by using 31P-magnetic resonance spectroscopy (MRS) and Xe-computed tomography (CT). The subjects studied were two patients with cerebrovascular dementia who had had frequent wandering episodes. The clinical diagnosis was Binswanger-type cerebral infarction in patient 1 and sequelae of cerebral bleeding and multiple lacunar infarctions in patient 2. Treatment with fasudil at 30 or 60 mg/day was given orally for 8 weeks. The wandering symptoms disappeared in both patients during the treatment and reappeared a few days after discontinuation of the treatment. Mental tests indicated that memory was mildly improved during the treatment. Pretreatment 31P-MRS findings revealed decreases in relative signal intensities of phosphomonoester and phosphodiesters and an increase in that of mean adenosine triphosphates. After treatment, these findings disappeared. The regional cerebral blood flow values by Xe-CT in both patients did not show significant changes from before treatment to the values after treatment. These results suggest that the efficacy of fasudil for the wandering symptoms and mental function observed in our patients may have been related to a direct effect on intracellular energy metabolism.

Histologic investigation of hollow implants retrieved for psychological reasons

OBJECTIVE

The purpose of this study was to radiologically, histologically, and histometrically evaluate bone in the hollow portion of three implants retrieved for psychological reasons.

STUDY DESIGN

Three hollow implants retrieved from two patients were studied. We investigated the radiologic and histologic changes of these implants with the use of radiographs, light microscopy, image processing, and fluorescent microscopy.

RESULTS

There were no radiologic and histologic degeneration around the implants. Histometric analysis of the hollow indicated that the average percentage of bone contact rate was 33.5% in case 1, 74.5% in case 2, and 18.4% in case 3; the average percentage of bone filling was 25.1%, 33.9%, and 6.6%, respectively. There was a great variation among the three cases in bone to implant contact and bone filling.

CONCLUSION

The hollow portion in case 1 that penetrated into the maxillary sinus was encapsulated with fibrous tissue. The amount of bone tissue in the hollow portion seems to depend on the initial bone quality of the recipient sites.

N-Shc: a neural-specific adapter molecule that mediates signaling from neurotrophin/Trk to Ras/MAPK pathway

Shc has been implicated in a variety of growth factor- and cytokine receptor-signaling through its specific binding to phosphotyrosine residues of the activated receptors. In neuronal cells, such as PC12, Shc has been shown to be involved in Ras-dependent MAP kinase activation following Trk receptor stimulation with NGF. While the ubiquitous role of Shc as an adaptor molecule in signal transduction is increasing in both neuronal and non-neuronal cells and tissues, the expression level of Shc is surprisingly low in the brain. We demonstrated here the isolation of a neural-specific member of the Shc family. This novel protein, named N-Shc (neuronal Shc), contains two potential phosphotyrosine-binding domains, PTB and SH2, and is expressed exclusively in the brain; whereas Shc is present in all other non-neuronal tissues. As in Shc, N-Shc can bind activated EGF receptor, become tyrosine phosphorylated, and form a complex with Grb2 adapter protein following EGF stimulation. Furthermore, N-Shc can bind activated TrkB receptor following the stimulation with brain-derived neurotrophic factor (BDNF), which is the most abundant neurotrophin in the brain. These data suggest that N-Shc, rather than Shc, mediates neurotrophin and other neuronal signalings in the central nervous system.

Active leprosy treated effectively with ofloxacin

The patient is a 25-year-old Filipino who showed polymorphous eruptions over the whole body, right ulnar nerve paresis, polyneuropathy and hypalgesia in the area of eruptions. Because the biopsy specimen showed foam cells, histiocytes, epithelioid cells, many Mycobacterium leprae and no giant cells, the diagnosis of borderline-lepromatous (BL) type was made. The symptoms were improved by the administration of 300 mg/day ofloxacin. Because the monotherapy using ofloxacin has been reported to be effective in all 5 previously reported cases of BL type leprosy, it may be recommended for a larger number of leprosy cases.

Laboratory examinations correlated with severity of dementia

Acetylcholine esterase, alpha 1-antichymotrypsin, homovanillic acid (HVA), 3-methoxy-4-hydroxy-phenylenglycol (MHPG), norepinephrine, dopamine, 5-hydroxy-indolacetic acid (5-HIAA), and gamma-aminobutyric acid (GABA) in the serum and cerebrospinal fluid (CSF) were quantified. Positive wave with the latency about 300 msec (P300) and electroencephalography (EEG) were examined in 10 patients with Alzheimer's disease, 10 patients with vascular dementia, and 10 age-matched healthy controls. Serum alpha 1-antichymotrypsin concentrations were significantly higher in the Alzheimer's disease group than in the vascular dementia and healthy control groups. Homovanillic acid concentrations in CSF were significantly lower in the vascular dementia group than in the Alzheimer's disease and the healthy control groups. A significant positive correlation was present between the mini-mental state examination (MMSE) score (normal range of 24 to 30) and the acetylcholine esterase concentration in the CSF. Significant negative correlations were present between the MMSE score and the P300 latency, between the MMSE score and the MHPG concentration in the CSF, between the MMSE and the norepinephrine concentration in the CSF, and between the MMSE score and the dopamine concentration in the CSF.

[Ipsilateral oculomotor nerve palsy and contralateral downbeat nystagmus due to unilateral paramedian thalamopenduncular infarction--a case report]

A case of midbrain and thalamic infarction which showed complete oculomotor nerve palsy of the ipsilateral eye and monocular downbeat nystagmus, ptosis, upward movement disturbance and adduction disturbance of the contralateral eye was reported. The patient is a 53-year-old woman who was admitted to our hospital because of sudden onset of double vision. Head magnetic resonance imaging showed unilateral midbrain and thalamic infarction. The midbrain lesion was located in the paramedian area and the bilateral ptosis, bilateral upward gaze palsy and adduction disturbance of the contralateral eye were considered to be caused by the lesion involving the unilateral oculomotor nucleus. This case is considered to be important because the association of contralateral monocular downbeat nystagmus is very rare.

Amino acid concentration in dementia of the Alzheimer type and multi-infarct dementia

Amino acids were measured in nine cases of dementia of the Alzheimer type, 10 cases of multi-infarct dementia, and 10 healthy controls. The severity of dementia was examined using mini-mental state test (MMST). Amino acid analysis (41 kinds) in the cerebrospinal fluid (CSF) and serum was performed in the Special Reference Laboratories. In the dementia of the Alzheimer type group, methionine and alanine concentrations in the CSF were significantly increased, and the CSF/serum ratios for both the alanine and glycine concentrations were significantly increased, in comparison with the healthy control group. In the multi-infarct dementia group, glycine, methionine, threonine, phenylalanine, and citrulline concentrations in the CSF were all higher than in the healthy control group. Significant negative correlations were found between the MMST score and the alanine, urea, arginine, and alpha-aminobutyric acid concentrations in the CSF. The number of amino acids which exhibited abnormality in dementia of the Alzheimer type and multi-infarct dementia was greater in the present study than in previous reports.

Evaluation of the peripheral circulatory status of the neonate during homeothermal adjustment by plethysmo-time-interval

The plethysmo-time-interval (PTI) is the time interval between the beginning of the QRS complex on an ECG and the upstroke of the pulse wave on a plethysmogram, as measured by pulse oximetry. In the present study, we investigated homeothermal acclimatization to the extra-uterine environment in human neonates using the Coretemp thermometer and a pulse oximeter. Temperature was measured at three sites: the central deep temperature (CDT) on the upper sternum, the peripheral deep temperature (PDT) on the flat part of the left sole of the foot and the surface temperature (ST) at the side of the abdomen. After delivery, CDT and ST were higher than PDT. The difference between CDT and PDT was large at first, but gradually decreased. PDT, initially in the range of 32.4 +/- 0.28 degrees C, reached a stable value (34.4 +/- 0.41 degrees C) at 2.5 h after delivery. PTI was prolonged in parallel with PDT. The difference between CDT and PDT probably reflected the contraction of skin vessels, particularly the arterioles, which occurs as a body defense mechanism against heat loss. As PTI was prolonged in parallel with PDT, we demonstrated objectively that this catch-up phenomenon of PDT after delivery was affected by the increase in skin blood flow as a result of dilatation of peripheral arterioles. It was concluded that PTI can be used to evaluate the peripheral circulatory status of the neonate, even during homeothermal adjustment after birth, by applying a new principle of pulse oximetry that is widely used in neonatal intensive care units.

Effects of intravenous L-dopa on P300 and regional cerebral blood flow in parkinsonism

The P300 and regional cerebral blood flow were measured before and after intravenous injection of L-dopa in 10 patients with idiopathic Parkinson's disease and 10 patients with vascular parkinsonism. The P300 was measured with an evoked potential recorder using an oddball paradigm and the regional cerebral blood flow was measured using the stable xenon computed tomography method. The P300 latency was significantly longer and the regional cerebral blood flow in the cerebral cortex and basal ganglia was significantly lower in the Parkinson's disease group and the vascular parkinsonism group than in the age-matched healthy control group. The intravenous injection of L-dopa improved these abnormalities significantly in the Parkinson's disease group but did not improve these abnormalities in the vascular parkinsonism group. Cognitive function is considered to be impaired in Parkinson's disease and vascular parkinsonism and L-dopa is considered to improve it in Parkinson's disease.

Histologic study of failed hollow implants

Nine hollow dental implants that were removed from patients were examined histologically to determine whether there was a common mechanism of failure with this implant design. When a hollow implant showed saucerized bone loss at the neck portion radiologically, the hollow portion was divided histologically into soft tissue and bone tissue. In advanced cases, stratified flattened epithelium that had invaded the hollow and the dead space at the top was observed. The condition of bone tissue located in the bottom of the basket can be adversely affected by an unfavorable crown-root ratio. The presence of an empty basket may cause fracture of the basket portion. The hollow portion can foster the growth of pathogenic bacteria. The hollow-type implant may not be suitable for immediate placement because surrounding soft tissues can invade the basket immediately.

Construction of highly extensive polymorphic DNA libraries by in-gel competitive reassociation procedure

Differential genomic DNA libraries between two mouse strains and from two human individuals were constructed by means of the in-gel competitive reassociation (IGCR) procedure, a procedure developed for cloning altered anonymous restriction fragments. The libraries were highly enriched in RFLP fragments, approximately 60 and 40% for the mouse and human libraries, respectively, and, more importantly, maintained most of the original complexities of the RFLP fragments. Therefore, differential genomic DNA libraries constructed by the IGCR procedure, particularly for human genomic DNA, should offer highly extensive sources for polymorphic DNA sequences necessary for a variety of genome analyses, including studies on the origin and mechanism of biological diversity among the same species.

[A case showing recurrence of myelopathy and optic nerve disturbance accompanied by pusturosis palmaris et plantaris and positive anticardiolipin antibody]

The patient is a 62-year-old woman who was admitted to our hospital with chief complaints of paresthesia in the four extremities and the trunk and gait disturbance in February 1993. Habitual abortions and left retrobulbar optic neuritis were present in the past history. She had been suffering from pusturosis palmaris et plantaris for 10 years. On admission, weakness of the distal muscles in the right upper extremity and severe disturbance of the deep sensations in the bilateral lower extremities and the right upper extremity were present. With the progress of the neurological symptoms, pusturosis palmaris et plantaris progressed. After the admission, the neurological symptoms became better by the administration of corticosteroid hormone medicine. After that, myelopathy and left optic nerve disturbance relapsed and IgG anti-cardiolipin antibody in the serum was present. The neurological symptom, pusturosis palmaris et plantaris and positive IgG anti-cardiolipin antibody in the serum may be caused by immunological mechanism. Anti-phospholipid antibodies such as IgG anti-cardiolipin antibody in the serum should be examined in patients with clinical multiple sclerosis like our case.