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Biomedical subjects

M Nakajima

Publications and source records attributed to M Nakajima.

At least 307 records · Page 17Linked to original sources
PubMed1999

[A successful surgical case of billowing mitral leaflet syndrome (Barlow syndrome) combined with severe mitral regurgitation].

We report a successful surgical case of billowing mitral leaflet syndrome combined with severe mitral regurgitation. A 45-year-old man suffered from congestive heart failure and admitted our institution for precise examination. A heart murmur was pointed out by a medical examination at his high school, and mitral valve prolapse was detected by echocardiography at 23 year of age. No medication was applied because he showed no symptom. From 44 year of age, he noted palpitation on exercise. Holter monitor showed blocked PAC and Wenckebach A-V block, and transesophageal echocardiography indicated severe mitral regurgitation due to the billowing of voluminous both leaflets. At his operation, we recognized the billowing of both leaflets with torn chordae, and size of the mitral valve orifice was 8.5 x 5 cm. The huge mitral valve was replaced with a CarboMedics 31M prosthetic valve by plicating mattress stitches of native mitral annulus. Histopathologic findings showed accumulation of acid mucopolysaccharide. Postoperative echocardiography showed reduction of the left ventricular volume and preservation of the left ventricular function. Relatively slow progression of the billowing mitral leaflet syndrome did not cause apparent symptoms of heart failure in this patient. Therefore, proper selection of the procedure and timing of surgical treatments might be important for successful long-term results after operation of the billowing mitral leaflet syndrome.

Cardiac Surgical Procedures↗
PubMed1999

[A successful case of simultaneous operation of aortic arch aneurysm and left lung cancer].

We report a simultaneous operated case of a 73-year-old man with aortic arch aneurysm and squamous cell carcinoma of the lung. Via median sternotomy, aneurysmectomy and graft replacement was performed under hypothermic circulatory arrest and selective brain perfusion. After changing the position, left upper lobectomy with lymph node dissection was performed via left posterolateral thoracotomy. In spite of using cardiopulmonary bypass, hemostasis was easy, and there was no complication through intra-operative to post-operative course. The cases of simultaneous operation of thoracic aortic aneurysm and lung cancer are rare, and only 3 cases have been reported in Japan. Under careful selection of the patients, simultaneous operations can be performed safely.

Aged↗
PubMed1999

Three-shell head model constructed from scalp geometry for electroencephalogram dipole localization.

One of the most sophisticated methods of dipole localization from (electroencephalograms) is based on a multi-compartment head model, which consists of the scalp, skull, cerebrospinal fluid (CSF) and brain cortex. The CSF layer in normal subjects is thin and can be ignored in dipole localization to good approximation. This multi-shell model is called the SSB (scalp-skull-brain) head model. The SSB head model is constructed from magnetic resonance imaging (MRI) or X-ray computed tomography slices of the head. These image slices, however, are not easy to obtain. The present paper presents a simple method for constructing the SSB head model only from the geometrical shape of the scalp, which is easily measured with a three-dimensional digitizer. We have derived a relationship between the head structure and the geometry of the head from statistical analysis of MRI slices of 12 normal subjects. The average estimation errors of the outer and inner boundaries of the skull were 1.2 and 2.2 mm, respectively. The head model thus estimated is called the sSSB (statistical SSB) model.

Adult↗
PubMed1999

Generation of rhythmical ingestive activities of the trigeminal, facial, and hypoglossal motoneurons in in vitro CNS preparations isolated from rats and mice.

The central pattern generator (CPG) for masticatory movements has been located in the medial bulbar reticular formation, by using cortically induced rhythmical jaw and tongue movements as a model. To analyze how stationary input from the cortex is transformed into rhythmical output in the neuronal population comprising the CPG, rhythmical neural activities representing rhythmical food ingestive movements were experimentally induced in vitro. Bath-application of N-methyl-D-aspartate (NMDA) induced rhythmical activities in the trigeminal (V), facial (VII) and hypoglossal (XII) nerves of in vitro brainstem-spinal cord preparations isolated from newborn rats and mice. This paper will review evidence for the notion that (1) the rhythmical XII nerve activity represents rhythmical sucking movements; (2) the population of neurons critically involved in the rhythm generation of the XII nerve is localized in the ventromedial medulla oblongata on both sides, and can induce rhythmical XII nerve activity on the same side independently of each other; (3) the rhythmical activities in the V, VII, and XII motoneurons are induced by separate CPGs, which are located segmentally at the respective level of the V motor, VII, and XII nuclei. In addition, rhythmical masticatory-like EMG activity of jaw muscles can be induced by repetitive stimulation of the pyramidal tract in the in vitro brainstem isolated from adult mice together with the oral-facial structures. We propose that the in vitro brainstem preparation is a useful tool for longitudinal analysis of postnatal development of the central pattern generation of food ingestive movements, including conversion from sucking to mastication.

Age Factors↗
PubMed1999

Bonding to caries-affected dentin using self-etching primers.

PURPOSE: To evaluate resin bond strengths to caries-affected versus normal dentin using three self-etching primer adhesive systems. MATERIALS AND METHODS: Carious lesions were excavated and then bonded with one of three self-etching primer adhesive systems (Clearfil Liner Bond 2, Clearfil Liner Bond 2V, A.R.T. Bond). A crown was then built up using a resin composite to a height of 4 mm. Five to six serial slabs approximately 0.7 mm thick were sectioned perpendicular to the bonded surface. The bonded caries-affected or normal dentin areas were isolated to create an hourglass configuration with a cross-sectional area of approximately 1 mm2. The specimens were subjected to tensile stress at a crosshead speed of 1.2 mm/min. The bonded interfaces to caries-affected and normal dentin were examined with an SEM. RESULTS: Clearfil Liner Bond 2 and Clearfil Liner Bond 2V produced high bond strengths to normal dentin, but significantly lower bonds than to caries-affected dentin. (P < 0.05). For A.R.T. Bond, there was no statistically significant difference between types of dentin. All three bonding systems produced thin (+/- 0.5-1.5 microns) hybrid layers in normal dentin. When used on caries-affected dentin, all self-etching primer systems produced hybrid layers that were twice as thick as those produced in normal dentin.

Acid Etching, Dental↗
PubMed1999

Correlation of E-cadherin and alpha-catenin expression with differentiation of oral squamous cell carcinoma.

The precise mechanism of disruption of cell-cell adhesion in oral squamous cell carcinomas has yet to be established. We therefore sought to clearly this mechanism by investigating expression of both E-cadherin (E-CD) and alpha-catenin (alpha-CAT), which is an intracellular CD-binding molecule, in squamous cell carcinomas of the tongue, gingiva and floor of the mouth using immunohistochemical and immunoblotting techniques. We found that reduced expression of both E-CD and alpha-CAT occurred more frequently in moderately- and poorly-differentiated carcinomas than in well-differentiated specimens (p < 0.001), and this reduced expression showed no regional specificity. Relatively frequent loss of alpha-CAT expression in poorly-differentiated carcinomas was detected by both immunohistochemical and immunoblotting analyses. These findings suggest that E-CD and alpha-CAT are both important regulators of intercellular adhesion, and that the reduction of these molecules is also linked to the process of tumor dedifferentiation.

Antibodies, Monoclonal↗
PubMed1999

The microtensile bond test: a review.

PURPOSE: The purpose of this review is to describe all of the various modifications of the microtensile bond test in one paper, so that investigators can select the modification that best suits their needs. METHODS: The essence of the microtensile test is the division of resin-bonded teeth into slabs between 0.5 and 1.0 mm thick that are then trimmed in such a manner that tensile force will be concentrated on the bonded interface during testing. Among the many advantages of the technique are that each tooth produces multiple specimens. Further, there is no need for a matrix to limit the bonded surface area, since the area is determined by the dimensions of the trimmed specimens. RESULTS: The various modifications of the microtensile test have been used to measure differences in regional bond strength across occlusal dentin, down the external surface of teeth from crown through roots, down the internal surface of root canals from cervical to apical thirds, as well as to compare normal vs caries-affected occlusal dentin and normal vs sclerotic cervical dentin. The technique is ideal for evaluating the long-term durability of resin-hard-tissue bonds. CONCLUSION: The microtensile test methods offer versatility that cannot be achieved by conventional methods. It is more labor-intensive than conventional testing, but holds great potential for providing insight into the strength of adhesion of restorative materials to clinically relevant sites and substrates.

Dental Bonding↗
PubMed1998

The effect of VIP/PACAP family of peptides on pancreatic blood flow and secretion in conscious dogs.

The effects of PACAP-38, PACAP-27, VIP and secretin on pancreatic blood flow were compared with those of meals in five conscious dogs using an ultrasound transit-time blood flow meter. All peptides (1-100 pmol/kg) induced dose-related increases of pancreatic blood flow, and fluid and bicarbonate secretion. Only PACAPs stimulated protein secretion. Both PACAPs at doses which did not stimulate pancreatic secretion, induced significant pancreatic vasodilatation. VIP was less potent than PACAP-38 and PACAP-27 at lower doses (1-25 pmol/kg), but was similar to PACAPs at higher doses. The maximal effects of PACAPs and VIP were comparable to those observed after meals. Secretin was a significant but weak vasodilator. When pancreatic secretion was maximally stimulated by secretin, a reduction of vascular resistance was 75% of postprandial peak levels. PACAP(6-38), a competitive antagonist of PACAP, inhibited pancreatic vascular responses to PACAPs, but not those to VIP and secretin. Its inhibitory effects on protein response to PACAPs were not significant. Atropine inhibited pancreatic protein but not the vascular effect of PACAP-27. Pancreatic vasodilatation by PACAPs appears to be mediated by both PACAP-specific and VIP/PACAP common receptors in dogs. PACAP, like VIP, is a good candidate for a mediator of atropine-resistant vasodilatation of the pancreas.

Animals↗
PubMed1998

Bovine lactoferrin stimulates the phagocytic activity of human neutrophils: identification of its active domain.

Bovine LF (bLF) at concentrations in the range of 50-250 micrograms/ml enhanced the phagocytic activity of human neutrophils as determined by measuring the incorporation of FITC-labeled latex beads by flow cytometry. The stimulatory effect of bLF was not abrogated by hydrolysis with pepsin. Bovine lactoferricin (bLFcin), which is a bactericidal fragment purified from a pepsin hydrolysate of bLF (bLFH), also enhanced the phagocytic activity, whereas, in contrast, the fraction of bLFH depleted of bLFcin showed no stimulatory effect. The phagocytosis-enhancing activity of bLF still remained after washing the neutrophils, following exposure to bLF. Also, bLF pretreatment of the latex beads stimulated their uptake. These results demonstrate that bLF is effective in promoting the phagocytic activity of human neutrophils. This activity appears to be due to its bLFcin domain and may involve dual mechanisms of direct binding to neutrophils and opsonin-like activity.

Animals↗
PubMed1998

Peptidyl human heart chymase inhibitors. 2. Discovery of highly selective difluoromethylene ketone derivatives with Glu at P3 site.

Appropriate structural modification of the difluoromethylene ketone derivatives at both P3 and P' positions led us to the discovery of peptidyl human heart chymase inhibitor 12h which shows potent activity with Ki = 6 nM and high selectivity against closely related serine protease bovine alpha-chymotrypsin (chymotrypsin Ki = > 100 microM). Using the compound 12b, a docking study with human heart chymase was carried out to presume probable interactions.

Animals↗
PubMed1998

Prognostic value of cyclin E and p53 expression in gastric carcinoma.

BACKGROUND: Cyclins and wild-type p53 are prime cell cycle regulators and may be involved in tumorigenesis. Cyclin E is a late G1 cyclin and its abnormalities have been reported in several cancers. The authors investigated the correlation between cyclin E expression and progression of gastric carcinoma. METHODS: The expression of cyclin E and p53 proteins was investigated retrospectively in 116 patients with gastric carcinoma. Immunohistochemical staining of the paraffin sections was performed using monoclonal antibodies to cyclin E and p53. RESULTS: The total cyclin E positive rate was 44.0% (51 of 116) of all cases, 26 of which were strongly positive. Strong cyclin E expression frequently was observed in deeply invasive tumors, tumors with lymph node metastasis, and tumors of advanced stage. The incidence of p53 expression was higher in the cyclin E positive tumors than in the other tumors. With regard to prognosis, patients whose tumors had both strong positivity for cyclin E and positivity for p53 had significantly poorer prognosis. In multivariate analysis, the combined variable of cyclin E and p53 was an independent prognostic indicator together with serosal invasion and tumor size. CONCLUSIONS: These data suggest the cyclin E expression correlates with p53 expression and may contribute to the progression of gastric carcinoma. The combined variable of cyclin E and p53 expression could be a useful prognostic indicator in patients with gastric carcinoma.

Adult↗
PubMed1998

Excess corticotropin releasing hormone-binding protein in the hypothalamic-pituitary-adrenal axis in transgenic mice.

Corticotropin-releasing hormone (CRH) is the primary hypothalamic releasing factor that mediates the mammalian stress response. The CRH-binding protein (CRH-BP) is secreted from corticotropes, the pituitary CRH target cells, suggesting that the CRH-BP may modulate hypothalamic-pituitary-adrenal (HPA) axis activity by preventing CRH receptor stimulation. Transgenic mice were generated that constitutively express elevated levels of CRH-BP in the anterior pituitary gland. RNA and protein analyses confirmed the elevation of pituitary CRH-BP. Basal plasma concentrations of corticosterone and adrenocorticotropin hormone (ACTH) are unchanged, and a normal pattern of increased corticosterone and ACTH was observed after restraint stress. However, CRH and vasopressin (AVP) mRNA levels in the transgenic mice are increased by 82 and 35%, respectively, to compensate for the excess CRH-BP, consistent with the idea that CRH-BP levels are important for homeostasis. The transgenic mice exhibit increased activity in standard behavioral tests, and an altered circadian pattern of food intake which may be due to transgene expression in the brain. Alterations in CRH and AVP in response to elevated pituitary CRH-BP clearly demonstrate that regulation of CRH-BP is important in the function of the HPA axis.

Adrenocorticotropic Hormone↗
PubMed1998

Serum matrix metalloproteinase-2 and its density in men with prostate cancer as a new predictor of disease extension.

We examined whether the serum matrix metalloproteinase-2 (MMP-2) level and MMP-2 density could be predictors of the development and extension of prostate cancer. Serum samples were collected before any clinical treatment from 98 patients with prostate cancer and from 76 patients with benign prostatic hyperplasia (BPH). Control sera were obtained from 70 healthy men. The serum level of MMP-2 was determined by 1-step enzyme immunoassay. A newly defined MMP-2 density parameter was determined by dividing the serum level of MMP-2 by the prostate volume, which was measured by ultrasonography. The mean serum level of MMP-2 in prostate cancer patients was significantly higher than in the control and BPH groups. Furthermore, the serum MMP-2 levels in prostate cancer patients with metastasis were highly elevated compared with those without metastases. The MMP-2 density in pathologically organ-confined prostate cancer was significantly higher than that in BPH. There was a statistically significant difference in the MMP-2 density between pT2N0M0 and pT1N0M0 prostate cancers. Moreover, the serum MMP-2 level correlated well with the clinical course of prostate cancer with bone metastasis. Our results suggest that MMP-2 plays an important role in the development and extension of prostate cancer and that the serum level of MMP-2 and the MMP-2 density indicate prostate cancer extension and are, therefore, useful for the followup of prostate cancer patients.

Aged↗
PubMed1998

Comparison of corticomotoneuronal EPSPs and macro-MUPs in amyotrophic lateral sclerosis.

We correlated the size of the corticomotoneuronal excitatory postsynaptic potential (CM-EPSP) arising in a single spinal motor neuron with the function of the target motor unit as measured by conventional and macro EMG in early amyotrophic lateral sclerosis (ALS). Macro motor unit potentials (macro-MUPs) were recorded from a surface electrode after spike-triggered averaging in the extensor digitorum communis muscle. The size of the CM-EPSP projecting to the same motor unit was measured from changes in the firing probability of single motor units induced by transcranial magnetic stimulation using peristimulus time histograms. In controls, the amplitudes of CM-EPSPs and macro-MUPs correlated inversely, probably reflecting a lower input resistance of larger spinal motoneurons. In ALS the amplitude of macro-MUPs did not correlate with that of CM-EPSPs and one third of normal ALS motor units had a reduced or temporally dispersed CM-EPSP. The findings indicate primary dysfunction of the corticomotoneuronal projection system in ALS that is independent of functional changes of spinal motoneurons.

Action Potentials↗
PubMed1998

Developmental toxicity of indium chloride by intravenous or oral administration in rats.

Pregnant rats were treated with a single intravenous or oral administration of indium chloride (InCl3) on day 9 of pregnancy and their fetuses were examined for growth and malformation on day 20 of pregnancy. By intravenous administration, fetal weight was significantly decreased and the incidences of fetal mortality and malformation were significantly increased at 0.4 mg In/kg. Fetal malformations of the tail and digits, e.g., kinked tail, brachyury, and oligodactyly, were observed at high incidences. By oral administration, similar tendencies in the fetal effects were observed, but there were no significant differences compared to the control even at 300 mg In/kg. Indium concentrations in the serum of pregnant rats showed low bioavailability of indium by oral administration. It was concluded from these results that indium showed teratogenicity in rats. Oral treatment with indium may be developmentally toxic at 300 mg In/kg, but this is difficult to state with certainty given the limited number of animals that were used in this study.

Abnormalities, Drug-Induced↗