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Biomedical subjects

K Nakai

Publications and source records attributed to K Nakai.

At least 217 records · Page 12Linked to original sources
PubMed1995

Difference of myosin heavy chain expression between mesangial cells and vascular smooth muscles.

Contraction of the pre- and postglomerular arteries play an important role in the regulation of glomerular blood flow. Mesangial cells may also be involved in the mechanism of this regulation, but it has not been clarified yet whether or not mesangial cells and vascular smooth muscles show an identical phenotype, especially in terms of their contractile proteins. In this study, in order to elucidate any difference in the cellular phenotypes between mesangial cells and renal vascular smooth muscles, we investigated the localization of myosin heavy chain isoforms using a monoclonal antibody against SM1 and SM2. Both SM1 and SM2 are specific to smooth muscles. SM1 is specifically expressed in smooth muscles from early development and SM2 appears after birth. In normal renal tissues, SM1 and SM2 were expressed only in the smooth muscle cells of the arterioles and small arteries. However, glomerular cells, including mesangial cells, were not stained with either anti-SM1 antibody or anti-SM2 antibody. Localization of SM1 and SM-2 was similar to that of alpha-smooth muscle actin (SM alpha-actin). Staining for SM-1 was not observed in the mesangial areas of renal tissues with glomerular disease. These results clearly indicate that mesangial cells have a different phenotype from that of vascular smooth muscle cells in terms of their contractile proteins.

Fluorescent Antibody Technique↗
PubMed1995

[Intrasellar arachnoid cyst: a case report].

Intrasellar arachnoid cyst is very rare. We report a case of intrasellar arachnoid cyst. A 44-year-old male was admitted for evaluation of his headache and visual disturbance on August 6, 1993. Neurological examination revealed bilateral decreased visual acuity and visual field defect. Endocrinological examination showed panhypopituitarism. Other neurological findings were normal. X-ray film of the skull showed a ballooning dilation of the sella turcica with thinning of the sellar floor. CT scan showed a cystic lesion with CSF-density occupied the sella. After intravenous administration of contrast medium, the cyst showed no enhancement. MRI showed the intrasellar mass had the same characteristics as the surrounding subarachnoid space. Bilateral carotid angiographies demonstrated that the carotid siphons were stretched and displaced laterally, and the A1 portions of the anterior cerebral arteries were raised. We made a diagnosis of intrasellar cystic lesion. On August 18, the sella turcica was opened via the transsphenoidal rhinoseptal approach. The cyst contained CSF-like fluid, and a part of the cyst wall was resected. The cavity was filled with Gelfoam and the sellar floor was repaired with bone flap. Postoperatively, the patient's visual disturbance improved, but diabetis insipidus appeared and required hormonal replacement. The patient was discharged on September 27 with improvement of visual acuity and visual field. Histological examination demonstrated that the cyst wall consisted of thick arachnoidal cells with fibrous connective tissue. The arachnoidal cells with oval nuclei was stained with epithelial membrane antigen. Symptoms, signs and radiological findings of intrasellar arachnoid cyst are similar to those of various sellar lesions including pituitary adenoma, craniopharyngioma, empty sella, Rathke's cleft cyst, epidermoid et al.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[A case of spinal dural arteriovenous fistula associated with normal pressure hydrocephalus].

A 62-year-old male presented with urinary incontinence, gait disturbance and dementia for 6 months. Neurological examination revealed severe paraparesis (1/5), sensory disturbance below Th10, neurogenic bladder and absence of patellar and achilles tendon reflexes. CT scan showed mild brain atrophy and symmetric ventriculomegaly with periventricular lucency. Magnetic resonance imaging (MRI) showed a linear flow void lesion on the dorsal surface on the back of his swollen lower spinal cord. Myelography showed a filling defect and flow disturbance of contrast medium in lower thoracic levels, suggesting the presence of adhesive arachnoiditis. Spinal angiography demonstrated a fistula formation between dural branches of bilateral L4 lumbar arteries and ventral spinal and radicular veins on the surface of the dura mater of L4/5 levels. Considering his past history of repeated lumbar puncture for tuberculous meningitis at the age of 22 years, a diagnosis of acquired spinal dural arteriovenous fistula probably due to repeated lumbar puncture was made. Fistulas were embolized with N-butyl cyanoacrylate. And normal pressure hydrocephalus was treated by ventriculoperitoneal shunt. Follow-up CT scans showed a decrease of the size of the ventricular system. Etiology of acquired spinal arteriovenous fistula has been reported. In the case, repeated lumbar puncture may be a possible cause of arteriovenous fistula in the lower spinal dura mater. However, the reason why it took so long to form a fistula after the lumbar puncture remains to be elucidated. We suggest that an increased protein concentration due to disturbance of cerebrospinal fluid flow might be a cause of normal pressure hydrocephalus (NPH).

Arteriovenous Fistula↗
PubMed1995

ST-segment/heart rate loop analysis on treadmill exercise testing can provide diagnostic and prognostic information in patients with stable effort angina.

BACKGROUND: In the assessment of myocardial ischemia and its severity using treadmill exercise testing (TMET), the magnitude of ST-segment depression is conventionally used. It is often difficult to distinguish false-positive from true ST-segment depression and to assess the severity of coronary artery disease (CAD). The purpose of the present study was to assess the ability of ST-segment/heart rate loop (ST/HR loop) analysis to provide diagnostic and prognostic information in patients with stable effort angina. METHODS: ST/HR loop analysis was studied in 118 patients with stable effort angina without previous myocardial infarction who were taking medication. ST/HR loop patterns were classified into four types: type A (n = 38), simple clockwise rotation; type B (n = 34), clockwise rotation with quick ST recovery in the first half; type C (n = 21), ST-segment depression that recovered at a constant rate; and type D (n = 25), simple counter-clockwise rotation. The control group consisted of 40 patients who had no ST-segment depression but were proved to have significant stenosis on coronary angiography. The ST/HR loop types were compared with (1) the conventional TMET parameters, (2) findings of coronary angiography, (3) severity of ischemia evaluated by exercise thallium-201 myocardial single-photon emission computed tomography (exercise TI-201 myocardial SPECT), and (4) short-term prognosis by follow-up study. RESULTS: The value of the simple heart-rate-adjusted ST-segment depression index (delta ST/HR index) in the type A group (6.1 +/- 5.8 microV/bpm) was higher (P < 0.05) than in the type C and D groups (2.7 +/- 2.0 microV/bpm and 1.7 +/- 1.2 microV/bpm, respectively). In the type A group, 68% of the patients had multiple diseased coronary arteries. In the type D group, 88% of the patients had either no significant coronary artery stenosis or significant stenosis in a single coronary artery. The ischemic size calculated by exercise TI-201 myocardial SPECT was higher (P < 0.05) in the type A group (47.6 +/- 24.6%) than in the type B, C, and D groups (21.4 +/- 16.6%, 14.9 +/- 15.8% and 7.8 +/- 7.4%, respectively). During the follow-up study nine cardiac events occurred in the type A group, three in the type B group, and one in the type C group. The prognosis of the type A patients was significantly worse than that of the type D and control patients (P < 0.01). CONCLUSION: We conclude that the ST/HR loop analysis is a simple and useful parameter for providing diagnostic and prognostic information for patients with stable effort angina.

Aged↗
PubMed1995

[Angiotensin-I converting enzyme].

Angiotensin I-converting enzyme (ACE) converts the largely inactive decapeptide angiotensin I to the active octapeptide angiotensin II. ACE is a key component of the renin-angiotensin system that has long been suspected to play a role in the pathogenesis of hypertension and cardiovascular disease. The ACE gene spans 21 kilobases and consists of 26 exons, and two different mRNAs and endothelial and testicular ACE are transcribed from the ACE gene. Circulating ACE probably originates from proteolytic cleavage of the hydrophobic anchor and passive leakage of the membrane-bound enzyme. Normal serum ACE by spectrophotometric assay is very low (8.3-21.4 microliters/ml). The abnormally elevated ACE levels is indeed a diagnostic aid in sarcoidosis. The ACE gene has 287 base pair insertion/deletion polymorphism in intron 16. The ACE deletion polymorphism appears to be associated with increased risk for myocardial infarction in the Caucasian and Japanese population. Recently in multicenter clinical trials (SAVE), administration of inhibitors of ACE were shown to decrease cardiac events after myocardial infarction.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

[The newly developed algorithm for signal-averaging ECG of P wave].

Signal-averaged P waves are available to evaluate patients at risk for paroxysmal atrial fibrillation. We developed a new algorithm of P wave triggered signal-averaged ECG applied the cross-correlation technique. Subjects consisted of 13 patients with paroxysmal atrial fibrillation (PAF group) and 12 normal volunteers (NOR group). ECG signals were amplified (5,000 times), filtered with band-pass filter (60-300 Hz) and averaged about 500 beats. The root mean square voltage for the total filtered P wave (P-RMS) and the duration of filtered P wave (FPD) were measured and were compared with those parameters obtained by level-slice P triggered method and R triggered method. The value of P-RMS in the all subjects was significantly higher by the cross-correlation method than that by the level-slice P triggered method (264 msec.microV versus 235 msec.microV, P < 0.001). The value of FPD in the PAF group was also significantly longer by the cross-correlation method than that by the level-slice P triggered method (151 msec versus 146 msec, P < 0.05). In conclusion, the cross-correlation method is suited for assessing P waves by the signal-averaged ECG.

Algorithms↗
PubMed1995

[Deletion polymorphism of the angiotensin I-converting enzyme gene associates with increased risk for ischemic heart diseases in the Japanese].

The Angiotensin I-converting enzyme (ACE) is a key component of the renin-angiotensin system thought to be important in the pathogenesis of hypertension and cardiovascular diseases. Previous studies showed that deletion polymorphism in the the ACE gene might be a risk factor for myocardial infarction in the Caucasian population, but, this finding has not yet been reported in a Japanese population. In this study, a 287 base pair (bp) insertion/deletion polymorphism in intron 16 of the ACE gene was examined by the polymerase chain reaction (PCR) in a cross-sectional study of 100 healthy subjects and 218 patients with ischemic heart diseases (IHD) (70 angina pectoris, 148 myocardial infarction). Polymorphism of the ACE gene was characterized by three genotypes: two deletion alleles (genotype DD), two insertion allele (genotype II) and heterozygotes alleles (genotype ID). No differences could be detected among the three genotypes for total cholesterol, high-density lipoprotein cholesterol, blood pressure and body mass index. The serum ACE activity in each II, ID and DD genotype was 11.4 +/- 2:7 microU/ml, 14.5 +/- 3.5 microU/ml, 16.6 +/- 4.6 microU/ml, respectively. In the population study, genotype DD was significantly associated with IHD when compared with the other two genotypes (ID and II). The frequency of deletion allele was higher (0.56) in the IHD group than in the normal individuals (0.42) (p < 0.05). These frequencies were not varied whether they had classic risk factors or not. Furthermore, coronary multivessel impairment was significantly associated with a deletion allele than with an insertion allele (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Effects on cognitive function and activities of daily living after stereotactic thalamotomy for Parkinson's disease].

Stereotactic thalamotomy was performed in ten patients with Parkinson's disease for the suppression of their tremor. After VL-thalamotomy, contralateral tremor and rigidity disappeared or was significantly reduced. Activities of daily living (ADL) measured by functional independence measure and Parkinson's disability score were improved postoperatively in all patients. There was significant improvement in anxiety index. However, other neuropsychological tests showed no significant change postoperatively. ADL improved after thalamotomy. It is concluded that stereotactic VL-thalamotomy is a useful treatment which improves ADL without cognitive dysfunction.

Activities of Daily Living↗
PubMed1995

[Identification of motor area by transcranial magnetic stimulation using an "eight-figure" coil in patients with motor paralysis].

In patients with motor paralysis, we tried to identify the functional motor area by transcranial magnetic stimulation using an "eight-figure" coil designed by Ueno. Motor evoked potentials (MEPs) were recorded in 7 patients from 50 to 64 years old, and in 5 normal volunteers 26 to 45 years old. They were stimulated at 49 points over an unilateral hand motor area, and at 21 points over a foot motor area, and surface MEPs were recorded on their contralateral thenar muscle and abductor hallucis brevis muscle. In normal volunteers, the optimal eddy current for stimulating the hand motor area was directed anteriorly parallel to the midline, and for stimulating the foot motor area, it was postero-laterally directed with an angle of 45 degrees towards the midline. MEPs could be induced at their muscle contractions during which their thumbs and middle fingers softly touched each other, and their halluxes slightly flexed. In five patients two kinds of amplitude mappings reconstructed from MEPs were obtained at rest or at muscle contraction. A line connecting these two peaks on an amplitude mapping was regarded as an "MEP-motor area". A geographical difference between the MEP-motor area and MRI-motor area (identified by an MRI surface image) was studied at muscle contraction and at rest. In normal subjects the sites of the MEP-motor area and of the MRI-motor area coincided, whereas, in patients with space-occupying lesions near the central sulcus, the MEP-motor areas were located 1 to 2cm posterior to MRI-motor areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Strictureplasty for Crohn's disease in Japan.

Strictureplasty has recently been advocated in the treatment of obstructive strictures of the small bowel in patients with Crohn's disease. In this group study, results for 69 patients with Crohn's disease who underwent strictureplasty were analyzed by sending questionnaires to 13 institutions belonging to the Research Committee of Inflammatory Bowel Disease of the Japanese Ministry of Health and Welfare. No mortality and anastomotic leakage were observed. Strictureplasties of both the Heineke-Mikulicz and Finney varieties were considered to be safe procedures, even though the sutures had to be applied at the slightly inflammed site. The median follow up was 37 months (range, 0-133 months), and 12 patients needed reoperation. The cumulative 3-year operation-free rate was 92.5% and the 5-year rate was 70.3%. The site of the lesion, the strictureplasty procedure, and previous history of small bowel resection did not significantly influence the operation-free intervals. The cumulative 5-year operation-free rate of the group treated with home elemental enteral nutrition (83.3%) was better than that of the non-treated group (65.3%). Strictureplasty was found to be a safe and effective surgical procedure for high-risk patients with Crohn's disease in whom an appropriate length of bowel should be saved.

Adult↗
PubMed1994

Increase of phosphotyrosine levels in mouse urine and liver during liver regeneration after partial hepatectomy.

To determine how cell proliferation contributes to phosphotyrosine (P-Tyr) level in body we investigated the changes of P-Tyr levels in mouse urine and liver during liver regeneration after partial hepatectomy (PH). After PH, the P-Tyr contents in urine and liver increased approximately 14- and 1.7-fold, respectively, at 2-4 days, and P-Tyr phosphatase activity in liver decreased to 50% at 2 days. These levels returned to the control level at 10 days. After orthovanadate administration, P-Tyr level increased as P-Tyr phosphatase activity decreased. These results suggest that P-Tyr level in liver is reflected in urinary P-Tyr level during liver regeneration, and P-Tyr phosphatase is important in the regulation of P-Tyr level.

Animals↗
PubMed1994

Construction of a novel database containing aberrant splicing mutations of mammalian genes.

To explore the rules for mammalian splice-site selection using a statistical approach, we constructed an aberrant splicing database containing an extensive collection of mammalian genetic disease mutations (90 genes, 209 mutations). From this database, we confirmed that: (1) more than 90% of mutations either destroy or create the splice-site consensus sequences; (2) the number of mutations mapped at individual residues in the splice-site regions roughly correlates to their conservation degrees in the consensus sequences; (3) about half of the observed aberrant splicing is exon skipping, while intron retention is rarely observed; (4) almost all of the major cryptic sites, activated by mutations, are mapped within an about 100-nt region from the authentic splice sites. Furthermore, we found that: (5) mutations are observed more frequently in the 5' splice-site region than in the 3' splice site region; (6) splice sites that are newly created by mutations are located upstream from the authentic splice sites. Hopefully, these observations will be used as rules for constructing a more effective prediction system of exon sequences.

Consensus Sequence↗
PubMed1994

Thallium-201 reinjection images can identify the viable and necrotic myocardium similarly to metabolic imaging with glucose loading 18F-fluorodeoxyglucose (18FDG)-PET.

We compared the usefulness of 18F-fluorodeoxyglucose (18FDG)-PET with glucose loading and thallium-201 (201Tl) reinjection imaging for determining the viability of the myocardium in 21 patients with an old anterior myocardial infarction. We obtained transaxial views during 201Tl reinjection imaging performed 10 minutes after post-exercise injection of 37 MBq 201Tl. PET imaging with 75 g oral glucose loading was performed 60 min after injection of 148 MBq of 18FDG. Wall motion was evaluated by echocardiography. Excellent 18FDG-PET images were obtained in 19 of 21 subjects in whom plasma glucose levels were below 251 mg/dl. The results of 201Tl reinjection imaging and 18FDG-PET imaging were in agreement in 20 of the 21 subjects. Echocardiography demonstrated hypokinesis or akinesis in segments identified as abnormal in imaging studies. Our results showed that 201Tl reinjection imaging identified the viable and necrotic myocardium similarly to metabolic imaging obtained by 18FDG-PET with glucose loading.

Adult↗
PubMed1994

Estradiol-17 beta regulates the induction of VCAM-1 mRNA expression by interleukin-1 beta in human umbilical vein endothelial cells.

We examined the effect of estradiol-17 beta on the expression of vascular cell adhesion molecule-1 (VCAM-1), an adhesion molecule, in human umbilical vascular endothelial cells. After preincubation with estradiol-17 beta for 24 hours, cells were treated for 4 h with 0.5 micrograms/ml recombinant human interleukin-1 beta. The RNase protection assay was performed using an [alpha-32P]-labeled 121 base pair VCAM-1 cRNA probe. Preincubation with estradiol-17 beta (250 or 500 pg/ml) suppressed the induction of VCAM-1 mRNA expression by interleukin-1 beta. VCAM-1 staining with a monoclonal antibody decreased when cells were incubated with estradiol-17 beta at 250 and 500 pg/ml, while staining was detectable when cells were treated with interleukin-1 beta at 0.5 micrograms/ml. In conclusion, estradiol-17 beta regulates the induction of VCAM-1 gene expression by interleukin-1 beta in human umbilical vein endothelial cells.

Antibodies, Monoclonal↗
PubMed1994

Regeneration of norepinephrine-containing fibers in occipital cortex of adult cats.

Regeneration of norepinephrine (NE)-containing nerve fibers in occipital cortex of adult cats was studied using morphological and biochemical methods. Initially, degeneration of cortical NE fibers was induced by direct infusion of 6-hydroxydopamine (6-OHDA) for a week. Cortical reinnervation by NE fibers continuously proceeded throughout 52 weeks, the longest survival period studied, after stopping 6-OHDA infusion. The rate of the reinnervation was slower in mature cortex than that obtained earlier in immature cortex. The present results indicate that the regenerative ability of the central NE neurons is universal, not limited to the immature brain. It is implied that the central NE neurons are equipped with a transmitter-specific repair mechanism throughout life.

Animals↗
PubMed1994

Enhancement of in vitro prostaglandin E2 production by mouse fibrosarcoma cells after co-culture with various anti-tumour effector cells.

We have previously reported that an increase in the production of immunosuppressive prostaglandin E2 by a QR tumour (QR-32) is accompanied by progressive growth of the tumour in syngeneic C57BL/6 mice. In order to determine what kinds of cell and factor(s) enable QR-32 cells to promote PGE2 production, we investigated the amounts of PGE2 in the supernatant of QR-32 cells by co-culturing them with various anti-tumour effector cells. Significantly high levels of PGE2 production were observed when the QR-32 cells were co-cultured with lymphokine-activated killer (LAK) cells, natural killer (NK) cells, polymorphonuclear (PMN) leucocytes and streptococcal preparation (OK432)-activated or resident peritoneal macrophages (activated and resident macrophages). On the other hand, PGE2 production was not increased when QR-32 cells were co-cultured with cytotoxic T lymphocytes (CTLs) specific to QR-32 cells. The high levels of PGE2 production were partially or totally inhibited by the presence of radical scavengers such as superoxide dismutase (SOD), catalase and mannitol, although the cytotoxicity of LAK cells was not. We also exposed QR-32 cells to human recombinant cytokines and the growth factors which are produced when anti-tumour effector cells come in contact with tumour cells. Significant PGE2 production by QR-32 cells was observed when the cells were treated with interferon alpha (IFN-alpha), tumour necrosis factor alpha (TNF-alpha) and transforming growth factor beta (TGF-beta) (all P < 0.001). These results suggest that oxygen radicals produced by anti-tumour effector cells and inflammatory cytokines provoke QR-32 cells to produce large amounts of immunosuppressive PGE2.

Animals↗
PubMed1994

Gnome--an Internet-based sequence analysis tool.

Gnome (GenomeNet Open Mail-service Environment) is a sequence analysis tool that enables an end-user to make use of several Internet- (mainly e-mail) based services with an easy-to-use graphical user interface. Users can conduct homology and motif searches, and database-entry retrieval against the latest databases by emitting search requests to and receiving their results form a search-server by e-mail. The search results are viewed and managed efficiently with this system. The Macintosh and X (Motif) versions of the Gnome client and the UNIX version of the Gnome server are available to academic users free of charge.

Computer Communication Networks↗