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Biomedical subjects

M Nakata

Publications and source records attributed to M Nakata.

At least 235 records · Page 13Linked to original sources
PubMed1991

Why are most GABA agonists not effective antiepileptic drugs?

The role of the GABAergic system in the induction and control of seizures remains elusive despite considerable research. In this report, the action of GABA agonists and antagonists is investigated both iontophoretically and intravenously on the trigeminal nucleus model. This technique permitted us to differentiate the direct effect of these drugs on the trigeminal neurons from the action on neurons elsewhere in the central nervous system which impinge on the trigeminal neurons.

Animals↗
PubMed1991

Afferent connections of the neurons in the Forel's field of H in cat.

An anatomico-physiological analysis was made to elucidate afferent connections of the neurons in the Forel's field of H (FFH) by horseradish peroxidase retrograde tracing technique and by evoked potential technique. 1) The FFH neurons receive fibers from the neocortex (layer V) and brainstem reticular formations. 2) Physiological projections from the mesencephalic reticular formation to the FFH as well as to the motor cortex were ipsilateral, but those from the pons and medulla oblongata were bilateral. 3) These data will suggest that the FFH neurons are in junction of the cortico-reticular connections and play an important role in the maintenance of an epileptic excitability of the neocortical system as suggested by Jinnai and Mukawa.

Afferent Pathways↗
PubMed1991

Quantitative assessment of quality of digitized portal images: receiver operating characteristic analysis applied to imaging in radiation therapy.

An objective and quantitative method for the evaluation of the quality of megavoltage portal images was developed by applying receiver operating characteristic analysis. On the basis of therapeutic use of portal images, setup errors were employed as "signals" in this experimental study that compared the original portal films with digitized images. Six readers observed 104 portal images of a chest phantom, half of which were "abnormal" (ie, had setup errors). Digital images (2,048 x 2,048 matrix) were enhanced by means of histogram equalization and then printed with a laser printer for observation. The readers showed a higher discrimination capacity with the digitally enhanced images, although a statistically significant improvement was not demonstrated. The present method of assessment of image quality proved to be both simple and clinically reasonable.

Humans↗
PubMed1991

Differential action of amitriptyline on neurons in the trigeminal nucleus.

We studied the effect of amitriptyline (AMI) on neurons in the spinal trigeminal nucleus caudalis in cats anesthetized with alpha-chloralose. The IV injection of 1.0 to 4.0 mg/kg AMI had a differential effect on the inhibitory mechanisms controlling the responses of these neurons. AMI significantly enhanced the segmental inhibition (SI) of wide dynamic range (WDR) neurons but had little or no effect on low-threshold mechanoceptive neurons. AMI also facilitated the SI of some nociceptive specific (NS) neurons and the periventricular inhibition of some WDR and NS neurons, but these effects were not statistically significant. Our observations suggest that AMI exerts its antineuralgic effect by enhancing the ability of SI to prevent excessive firing of WDR neurons. This supports the notion that neuropathic pain is caused by dysfunction of inhibitory mechanisms in the CNS.

Action Potentials↗
PubMed1991

Changes in levels of arachidonic acid metabolites in blood and bronchoalveolar lavage fluid after warm ischemia-reperfusion of lung.

The purpose of this study was to evaluate the role of arachidonic acid metabolites in the reimplantation response after lung transplantation in mongrel dogs. The left lung was used and two groups were studied. Group I underwent hilar stripping, while Group II underwent hilar stripping plus warm ischemia for 60 min., achieved by clamping the left pulmonary artery and veins. We measured the lung wet to dry weight ratio (W/D ratio), total pulmonary vascular resistance (TPVR), and blood and bronchoalveolar lavage fluid (BALF) levels of leukotriene B4 and C4 (LTB4,C4) and thromboxane B2 (TXB2). These parameters were measured periodically for 7 days after reperfusion. In group II, the W/D ratio and TPVR were significantly increased in comparison with Group I. The blood LTC4 level was elevated immediately after reperfusion, and BALF level of LTC4 also rose subsequently. These levels changed concomitantly with the W/D ratio. The above results suggest that arachidonic acid metabolism plays an important role in the reimplantation response, especially in pulmonary edema.

Animals↗
PubMed1991

[Detection of the new tumor marker MUSE 11 antigen in sera of pancreatic cancer patients: a comparison with sialyl SSEA-I antigen].

Using sera from patients with pancreatic cancer and chronic pancreatitis, we measured the level of the adenocarcinoma-associated antigen MUSE 11. A comparative study between levels of MUSE 11 and levels of sialyl SSEA-1 antigen (SLX) was also carried out. With respect to the MUSE 11 antigen, positive incidence was found in 17 out of 26 pancreatic cancer patients (65%), and in 1 out of 13 chronic pancreatitis patients (8%). Similar results were obtained from the assay of SLX levels. However, no correlation was found between the two markers. Out of 9 samples which showed MUSE 11 negative, three were positive for SLX. Out of 13 samples showing SLX negative, seven were positive for MUSE 11. Twenty out of 26 (77%) cases showed positive results for either antigen. These data suggest that the MUSE 11 antigen may be useful for the diagnosis of pancreatic cancers.

Adult↗
PubMed1991

[The examination of DNA strand breaks induced by peplomycin-using non-radioactive in situ nick translation method].

In situ nick translation (ISNT) is a method to detect DNA single strand break (nick) at each cellular level. In this study, peplomycin (PEP)-induced DNA strand breaks and its repair were examined using non-radioactive ISNT method. Human fibroblasts were cultured with various concentrations of PEP for different durations, and then DNA strand breaks were evaluated by ISNT method. The signal intensity of DNA strand breaks of the PEP-treated fibroblasts was increased in a dose dependent manner. At the fixed concentration of PEP, it reached to a maximum level after 10 min. of culture and remained unchanged for at least 24 hours. In addition, DNA strand breaks induced by PEP was rapidly repaired in 10 min. after washing. Thus, the non-radioactive ISNT is thought to be a quick, sensitive and specific method not only to detect DNA strand breaks but also to observe its repair.

Bleomycin↗
PubMed1991

[Two-dimensional and Doppler echocardiographic evaluation of intrauterine blood flow dynamics in the fetuses with a ventricular septal defect].

In nine fetuses with ventricular septal defect (VSD), intracardiac blood flow was observed with color Doppler ultrasound. Interventricular shunt velocity, maximum systolic velocity in the ascending aorta and pulmonary artery, trans-atrioventricular blood flow velocity, and the flow pattern in the inferior vena cava were also measured with pulsed Doppler ultrasound. The cardio-thoracic ratio and ejection fraction were measured by B- and M-mood ultrasound. In all four fetuses with isolated VSD a bidirectional shunt was demonstrated. In the three normal developed fetuses time analysis showed a right (RT)-to-left (LT) shunt during systole and a LT-to-RT during diastole with maximum systolic velocities of 61cm/s, 42cm/s and 68cm/s. In the five fetuses with complexed cardiac malformation, two fetuses had a unidirectional shunt and three fetuses had a bidirectional shunt, which was a LT-to-RT during systole and a RT-to-LT during diastole. These studies indicate that although the systolic pressure in the right ventricle is slightly higher than that in the left, the pressure is almost the same in both ventricles. The presence of unidirectional shunting or a different time relationship from that of normal fetuses in bidirectional shunting would necessitate a careful check for other cardiac malformations.

Blood Circulation↗
PubMed1991

[The stomatognathic function in a case of hemifacial hypertrophy--findings of mandibular movement].

We have been treating a girl with hemifacial hypertrophy since she was 5 years 8 months old. We analyzed her stomatognathic function, the dentition and occlusion, X-ray findings of TMJ, tooth contact and measurements of mandibular movement, at 9 years 2 months. The results were as follows: 1. The maxillary dental arch was almost symmetrical, but the mandibular one was complicatedly distorted in the up and down directions, and largely shifted to the left side. As a result the patient was able to occlude in the severe cross-bite condition of the area from incisors to left molars. 2. The patient had many tooth contact points on the right side and few on the left side when she bit at the intercuspal position and at the both lateral excursions. 3. From the analysis of the mandibular movements on the protrusion, lateral excursion and maximum open and close positions, it was suspected that the shift of right condyle was much less than the left one, and showed as almost rotating movement. 4. It could be concluded that the patient was accustomed to having more tooth contacts in the right dentition than in the left one because of the hypertrophy of the right half of mandible, so that she could only masticate with the right teeth also the anterior displacement of disk with reduction was resulted on the right condyle and the asymmetrical mandibular movement was noted.

Child↗
PubMed1991

Surface condition of primary teeth after approximal grinding and polishing.

Mesiodistal reduction of primary teeth is necessary in cases with mild or moderate primary crowding, in patients treated with Fränkel appliance type I or II or in those who need to keep a primary molar as long as possible due to congenitally missing premolars. In order to minimize the risks of periodontal destruction and caries, the tooth surface should be polished after grinding. A technique for stripping permanent teeth, recently proven successful in achieving smoother enamel than untreated tooth surfaces, was slightly varied and applied to primary teeth. By means of scanning electron micrographs, it could be shown that application of this technique produces smooth surfaces on primary teeth as well. The procedure is described in detail and cases in which it should be used are presented.

Child↗
PubMed1991

[A comparison of measurements of serum free thyroxine concentration by equilibrium dialysis and ultrafiltration using undiluted serum].

We have examined the clinical usefulness for free thyroxine (FT4) measurement by equilibrium dialysis of undiluted serum and by radio-immunoassay of T4 concentration in the dialysate (ED/RIA). The results were compared with those by ultrafiltration of undiluted serum (UF/RIA), which is believed to offer the best possible approach towards estimation of in vitro serum level of FT4. The precision with both methods was excellent. There was a high degree of correlation of FT4 concentration by both methods (r = 0.831, p less than 0.001, n = 99). FT4 concentration by ED/RIA and UF/RIA methods agreed well for hyperthyroidism, hypothyroidism, normal pregnancy, and for low T4-binding globulin concentration. In nonthyroidal illness (NTI), FT4 levels were all within or above normal for UF/ED method, while some FT4 values in low T4 syndrome were below normal for ED/RIA method. The effect of progressive serum dilution on FT4 concentration was also examined for both methods. There was no fall in FT4 concentration in sera from normal, hyperthyroid patient and in serum with low T4 syndrome for both methods, but in a serum from low T3 syndrome, there was a fall in FT4 concentration by dilution with UF/RIA method, indicating that serum dilution with ED/RIA method might underestimate FT4 concentration in some NTI sera. From these results it is concluded that the present ED/RIA method is adaptable to clinical laboratory use as a reference standard method for FT4 measurement.

Adult↗
PubMed1991

[Chronic subdural hematoma secondary to coagulopathy].

Eleven cases of chronic subdural hematoma (CSH) secondary to coagulopathy were experienced in our department in the last 5 years. They were classified into 4 groups, I: secondary to diffuse metastatic carcinomatosis of the bone marrow (4 cases), II: malignant hematological disease (acute lymphocytic leukemia and myelodysplastic syndrome 1 case each), III: postreplacement of cardiac valves or vein graft having been treated with anticoagulants (warfarin) (3 cases) and IV: chronic renal failure after having been hemodialyzed (2 cases). The outcomes were all good in group III, and there was one good outcome in group IV. However, death was the outcome in all the other cases. Conservative treatment (mannitol and steroid for 2 weeks) was carried out in 4 cases, all of which improved clinically with diminished hematoma. In 9 cases, surgical treatment was attempted by means of burr hole irrigation of the hematoma. Two of them developed intracerebral hematoma, and one developed acute brain swelling. In conclusion, treatment of CSH secondary to coagulopathy should be selected as follows. 1. Conservative treatment is to be the first choice, if conditions allow it. 2. Surgery can be performed by burr hole irrigation when indicated. Precautions should be taken not to injure the inner membrane of the hematoma or the brain proper, and the need for slow decompression should be kept in mind.

Aged↗
PubMed1990

Cloning of cDNA for proteinase 3: a serine protease, antibiotic, and autoantigen from human neutrophils.

Closely similar but nonidentical NH2-terminal amino acid sequences have been reported for a protein or proteins in human neutrophils whose bioactivities is/are diverse (as a serine protease, antibiotic, and Wegener's granulomatosis autoantigen) but that share(s) several features: localization in the azurophil granules, a molecular mass of approximately 29 kD, reactivity with diisopropylfluorophosphate, and the ability to degrade elastin. We previously purified one such entity, termed p29b. Using a monospecific antibody, we have cloned from human bone marrow a cDNA encoding the complete p29b protein in its mature form, along with pre- and pro-sequences. The predicted amino acid sequence agrees closely with the NH2-terminal sequence obtained previously from purified p29b, as well as with sequences newly obtained from CNBr fragments. The primary structure is highly homologous to elastase, cathepsin G, T cell granzymes, and other serine proteases, and shares both the catalytic triad and substrate binding pocket of elastase. Hybridization of the full-length cDNA with restriction enzyme digests of human genomic DNA revealed only one fragment. This suggests that the closely related species described previously are the same, and can be subsumed by the term used for the first-described activity, proteinase 3. Proteinase 3 is more abundant in neutrophils than elastase and has a similar proteolytic profile and specific activity. Thus, proteinase 3 may share the role previously attributed to neutrophil elastase in tissue damage, and has the potential to function as an antimicrobial agent.

Amino Acid Sequence↗
PubMed1990

Constitutive expression of pore-forming protein in peripheral blood gamma/delta T cells: implication for their cytotoxic role in vivo.

The cytotoxic activity and pore-forming protein (PFP) expression of human peripheral blood (PB) gamma/delta T cells were examined. Fresh gamma/delta T cells isolated from PB lymphocytes by fluorescence-activated cell sorting exhibited a substantial natural killer-like cytotoxic activity against K562 target cells and had a high cytotoxic potential triggered by anti-CD3 monoclonal antibody (mAb) against P815 target cells bearing Fc gamma R. Immunocytochemical staining with an anti-PFP mAb revealed that virtually all PB gamma/delta T cells are granular lymphocytes with abundant PFP in their cytoplasmic granules. Constitutive expression of PFP in PB gamma/delta T cells was also demonstrated by Northern blot analysis. These observations support the proposed role of gamma/delta T cells in cytolytic immune surveillance in vivo.

Antibodies, Monoclonal↗
PubMed1990

Interleukin 2 induction of pore-forming protein gene expression in human peripheral blood CD8+ T cells.

Our studies have analyzed pore-forming protein (PFP) mRNA expression in resting and stimulated human peripheral blood CD3- large granular lymphocytes (LGL), CD3+ T cells, and their CD4+ or CD8+ subsets. Signals that stimulate T cells to develop cytotoxic activity (i.e., IL-2 or OKT-3 mAb) led to the induction of PFP mRNA in T cells. The data indicated that IL-2 directly increased PFP mRNA in the CD8+ subset of T cells, in the absence of new DNA or protein synthesis. Abrogation of IL-2-induced PFP mRNA expression and cytotoxic potential of T cells by the anti-p75 IL-2 receptor mAb suggested that low numbers of p75 IL-2 receptors on CD8+ T cells were capable of transducing signals responsible for these IL-2-induced effects. The induction of T cell PFP mRNA via CD3, using OKT-3 mAb, was less rapid but greater than that caused by IL-2; however, a combination of PMA and ionomycin, which bypasses crosslinking of the TCR/CD3 complex, could not mimic this increase in PFP mRNA levels in T cells. The role of second messenger systems in regulating PFP mRNA expression remains to be determined. In contrast, high constitutive PFP mRNA expression was observed in CD3- LGL and these mRNA levels could not be enhanced by stimulation with IL-2. The cytotoxic potential of peripheral blood T cells and LGL induced in response to IL-2 correlated with IL-2-induced PFP mRNA levels in these cells and was consistent with PFP being one of several important molecules involved in the effector function of cytotoxic lymphocytes.

Antibodies, Monoclonal↗