Search PubMed⌕ Search

Biomedical subjects

M Takada

Publications and source records attributed to M Takada.

At least 91 records · Page 5Linked to original sources
PubMed2000

Protection against dopaminergic nigrostriatal cell death by excitatory input ablation.

The importance of enhanced glutamatergic neurotransmission in the basal ganglia and related structures has recently been highlighted in the development of Parkinson's disease. The pedunculopontine tegmental nucleus (PPN) is the major origin of excitatory, glutamatergic input to dopaminergic nigrostriatal neurons of which degeneration is well known to cause Parkinson's disease. Based on the concept that an excitatory mechanism mediated by glutamatergic neurotransmission underlies the pathogenesis of neurodegenerative disorders, we made an attempt to test the hypothesis that removal of the glutamatergic input to the nigrostriatal neurons by PPN lesions might prevent 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced parkinsonism in the macaque monkey. The PPN was lesioned unilaterally with microinjection of kainic acid, and, then, MPTP was administered systemically. In these monkeys, the degree of parkinsonian motor signs was behaviourally evaluated, and the histological changes in the dopaminergic nigrostriatal system were analysed by means of tyrosine hydroxylase immunohistochemistry. The present results revealed that nigrostriatal cell loss and parkinsonian motor deficits were largely attenuated in the MPTP-treated monkey group whose PPN had been lesioned, compared with the control, MPTP-treated monkey group with the PPN intact. This clearly indicates that the onset of MPTP neurotoxicity is suppressed or delayed by experimental ablation of the glutamatergic input to the nigrostriatal neurons. Such a protective action of excitatory input ablation against nigrostriatal cell death defines evidence that nigral excitation driven by the PPN may be implicated in the pathophysiology of Parkinson's disease.

Animals↗
PubMed2000

Impairment of mycophenolate mofetil absorption by iron ion.

OBJECTIVE: We sought to evaluate the effect of iron ion on the absorption of mycophenolate mofetil, which is an immunosuppressive agent. The pharmacokinetics of mycophenolic acid were studied. METHODS: A randomized crossover design with two phases was used. A 7-day washout period separated the two treatment conditions. In the first phase, the volunteers received 1.0 g of mycophenolate mofetil alone (study 1); in the second phase, the volunteers received 1.0 g of mycophenolate mofetil and 2 tablets of iron ion preparations concomitantly (study 2). The serum concentration of mycophenolic acid, which is a pharmacologically active metabolite, was measured by reverse-phase HPLC. RESULTS: The area under the plasma concentration-time curve from 0 to 12 hours and the maximum concentration of mycophenolic acid in study 2 were significantly less than in study 1 (area under the curve, 32.9 +/- 14.7 versus 2.92 +/- 0.883 microg x h/mL, P < .001, maximum concentration, 20.1 +/- 9.21 versus 1.30 +/- 0.367 microg x h/mL, P < .001). CONCLUSIONS: This finding shows that when mycophenolate mofetil and iron ion preparations were administered concomitantly, a remarkable decrease of mycophenolate mofetil absorption was observed. Therefore it seems to be clear that we must avoid the concomitant administration of mycophenolate mofetil and iron ion preparations.

Adult↗
PubMed2000

Phase I and pharmacologic study of docetaxel and irinotecan in advanced non-small-cell lung cancer.

PURPOSE: We conducted a phase I trial of docetaxel, a new antimicrotubule agent, combined with irinotecan (CPT-11), a topoisomerase I inhibitor. The aim was to determine the maximum-tolerated dose (MTD) of docetaxel combined with CPT-11, as well as the dose-limiting toxicities (DLTs) of this combination in advanced non-small-cell lung cancer (NSCLC) patients. PATIENTS AND METHODS: Thirty-two patients with stage IIIB or IV NSCLC were treated at 4-week intervals with docetaxel (60 minutes, day 2) plus CPT-11 (90 minutes, days 1, 8, and 15). The starting doses of docetaxel/CPT-11 were 30/40 mg/m(2), and doses were escalated in 10-mg/m(2) increments until the MTD was reached. RESULTS: The MTD of docetaxel/CPT-11 was 50/60 mg/m(2) (level 5A), or 60/50 mg/m(2) (level 5B). Neutropenia and diarrhea were the DLTs. CPT-11 did not affect the pharmacokinetics of docetaxel. There were 11 (37%) partial responses among 30 patients. The median survival time was 48 weeks, and the 1-year survival rate was 44.9%. CONCLUSION: The combination of docetaxel and CPT-11 seems to be active against NSCLC, with acceptable toxicity. The recommended dose for phase II studies is 50 mg/m(2) of CPT-11 (days 1, 8, and 15) and 50 mg/m(2) of docetaxel (day 2) administered every 28 days.

Adult↗
PubMed2000

Experimental allergic conjunctivitis in guinea pigs induced by Japanese cedar pollen.

We report a new experimental allergic conjunctivitis with Japanese cedar pollen as antigen in guinea pigs, and the immunological characteristics of this model were also elucidated. Allergic conjunctivitis was developed by immunization in guinea pigs with a mixture containing Japanese cedar pollen and killed Bordetella pertussis. When local application of Japanese cedar pollen suspension 14 d after systemic immunization was performed every 3d, remarkable conjunctivitis was observed from 20 to 35 d. Increase in vascular permeability and decrease in histamine contents of the conjunctiva were also observed after local application of antigen. Passive cutaneous anaphylactic (PCA) reactions revealed that both IgG- and IgE-rich antibodies were produced in this model. Chlorpheniramine, ketotifen and levocabastine were effective in inhibiting cedar pollen-induced conjunctivitis. Although a high concentration was needed, tranilast and amlexanox also showed significant inhibition of conjunctivitis induced by cedar pollen.

Animals↗
PubMed2000

Mixed carcinoid-adenocarcinoma of the liver.

A 61-year-old man with a mixed carcinoid-adenocarcinoma of the liver is described. Microscopic examination of the lesion showed a differentiated adenocarcinoma with distinct carcinoid components that stained positively for argyrophil. The tumor cells contained serotonin granules on immunohistochemical studies. Detailed examination disclosed no primary tumor in the gastrointestinal tract or in any other organ. Resection was considered impractical because there were multiple tumors. The patient received chemotherapy six times (cisplatin 60 mg/m2, epirubicin 40 mg/ m2 per month). The multiple tumors gradually shrank. At the time of this writing, the patient is still alive. To our knowledge, this is the first reported case of mixed carcinoid-adenocarcinoma of the liver.

Adenocarcinoma↗
PubMed2000

[Brain lesion in congenital myotonic dystrophy].

Congenital myotonic dystrophy (CMyD) affects the brain, causing mental changes and psychomotor retardation. However, the pathophysiology of the brain dysfunctions in CMyD remain to be clarified. We described two cases of CMyD with brain abnormalities. Case 1 was diagnosed as having ventricular dilation at 17 days after birth, and died at 3 years and 6 months. Case 2 was diagnosed as having ventricular dilation at birth, and died at 1 year and 3 months. Pathologically, both cases showed remote hypoxic ischemic brain damage and leptomeningeal glioneuronal heterotopia (LGH). In our patients, the white matter changes may have been caused by perinatal asphyxia, and LGH by embryological abnormalities. Taken our data and those of previous reports together, it is suggested that cerebral abnormalities in CMyD are ascribed to both hypoxic ischemic changes and histogenetic abnormalities.

Asphyxia Neonatorum↗
PubMed1999

Dose-dependent transduction of vesicular stomatitis virus G protein-pseudotyped retrovirus vector into human solid tumor cell lines and murine fibroblasts.

We examined the transduction efficiency of a VSV-G (vesicular stomatitis virus G protein)-pseudotyped vector encoding beta-galactosidase (lacZ) into human solid tumor cell lines and murine fibroblasts, compared with that of an amphotropic vector carrying the same RNA sequence. The ratio of cells transduced with the VSV-G-pseudotyped vector corresponded closely to 1 - e(-m.o.i.), as predicted from a Poisson distribution of transduction to the entire cellular population, while this was not the case for the amphotropic vector. Here m.o.i. (multiplicity of infection) is defined as the ratio of input infectious units (titrated on the corresponding cell line) to the number of cells used for the transduction. At high m.o.i.s (values greater than 3), the VSV-G-pseudotyped vector transduced approximately 95% of the culture population of all cell lines examined. The transduction efficiency of the amphotropic vector, however, was not dose-dependent and reached a plateau or even decreased, especially at high m.o.i.; this may be attributable at least in part to the presence of envelope protein and noninfectious particles that compete for the receptor of infectious amphotropic virus. The copy number of integrated vector proviral DNA and the expression level of lacZ increased almost linearly with the dose of the VSV-G-pseudotyed vector, which could readily achieve multiple transduction of more than 10 copies per cell and afforded about 100-fold more transgene product than could be achieved with the amphotropic vector. These features of both the VSV-G-pseudotyped vector and the amphotropic vector were essentially unaffected by purification using centrifugation. These properties of the vector should be highly advantageous for gene transfer into entire populations of human tumor cell lines at a designed dosage.

Animals↗
PubMed1999

Corticostriatal and corticosubthalamic input zones from the presupplementary motor area in the macaque monkey: comparison with the input zones from the supplementary motor area.

The presupplementary motor area (pre-SMA) is a cortical motor-related area which lies in the medial wall of the frontal lobe, immediately anterior to the supplementary motor area (SMA). This area has been considered to participate in the control of complex forelimb movements in a way different from the SMA. In an attempt to analyze the patterns of projections from the pre-SMA to the basal ganglia, we examined the distributions of pre-SMA inputs in the striatum and the subthalamic nucleus and compared them with the SMA input distributions. To detect morphologically the terminal fields from the pre-SMA and the forelimb region of the SMA, anterograde tracers were injected into such areas that had been identified electrophysiologically in the macaque monkey. Corticostriatal inputs from the pre-SMA were distributed mainly in the striatal cell bridges connecting the rostral aspects of the caudate nucleus and the putamen, as well as in their neighboring striatal portions. These input zones were located, with no substantial overlap, rostral to corticostriatal input zones from the SMA forelimb region. Corticosubthalamic input zones from the pre-SMA were almost localized in the medial aspect of the nucleus, where corticosubthalamic inputs from the SMA forelimb region were also distributed predominantly. However, the major terminal fields from the pre-SMA were centered ventrally to those from the SMA. The present results indicate that the corticostriatal and corticosubthalamic input zones from the pre-SMA appear to be segregated from the SMA-derived input zones. This implies the possibility of parallel processing of motor information from the pre-SMA and SMA in the cortico-basal ganglia circuit.

Animals↗
PubMed1999

Corticostriatal projections from distal and proximal forelimb representations of the monkey primary motor cortex.

Corticostriatal projections from one distal and two proximal subregions in the forelimb representation of the primary motor cortex (MI) were examined in the macaque monkey. The distal and proximal subregions in the anterior bank of the central sulcus (distal and proximal-bank subregions) and the proximal subregion in the surface of the precentral gyrus (proximal-surface subregion) of the MI were identified using intracortical microstimulation. Different anterograde tracers were then injected into two of these three forelimb subregions of the MI. In the ipsilateral putamen, the distribution areas of corticostriatal fibers from the distal, proximal-bank and proximal-surface subregions were arranged from ventrolateral to dorsomedial in this order. These corticostriatal input zones were largely segregated from one another.

Animals↗
PubMed1999

Diagnostic imaging of early gallbladder cancer: retrospective study of 53 cases.

To diagnose early gallbladder carcinoma is difficult but essential to improve the survival of the patients with this cancer. Fifty-three early gallbladder cancers were macroscopically divided into protruding and flat types. The diagnostic devises [ultrasonography (US), computed tomography (CT), and drip infusion cholangiography (DIC)] were compared for their ability of early detection. The specimens were examined cytologically for diagnosis during operation and the p53 protein was investigated. Thirty-three cases were of the protruding type, eighteen of the flat type, and two unclassified. Carcinoma tended to be missed when gallstones were present. Preoperative diagnosis of the flat type was difficult. Tumor location did not always correlate with the preoperative diagnosis. Of the misdiagnosed cases of the protruding type, half were missed with US and CT and were not visualized clearly by DIC. Among the flat type cancers, only three had no abnormal findings by diagnostic imaging. Cytologic examination was effective, and p53 was expressed only in early carcinoma, not in adenoma or dysplasia. Even in the presence of gallstones or cholecystitis, any abnormal findings should make one suspicious of gallbladder cancer. Cytology and p53 expression may be useful for the intraoperative diagnosis, and a combination of diagnostic methods is important.

Adenoma↗
PubMed1999

Comparison of bone mineral density at various skeletal sites with quantitative ultrasound parameters of the calcaneus for assessment of vertebral fractures.

This study investigated the role of quantitative ultrasound (QUS) for evaluation of fracture risk in comparison with bone mineral density (BMD) measurement. Our subjects were postmenopausal Japanese women (n = 260; age, 67 +/- 6.1 years) who were examined for bone densitometry, QUS, and spinal X-ray examination at our department between 1992 and 1996. The subjects were categorized into three groups by the number of atraumatic fractured vertebrae: NF, no vertebral fractures: F1, one vertebral fracture; F2, two or more vertebral fractures. We compared the measured parameters to determine their association with the number of fractured vertebrae. Differences among groups were compared and analyzed by Student's t-test. Odds ratios were also calculated after age adjustment, as well as age and lumbar or calcaneal parameters. Between NF and F1, lumbar BMD and BMD of the Ward's triangle showed more significant differences than other values, while between F1 and F2, whole-body BMD and QUS parameters showed more significant differences. Lumbar BMD also showed the highest age-adjusted odds ratio in differentiating F1 from NF. Although QUS parameters showed no power to differentiate between NF and F1, these values showed higher odds ratios than other measurements for discriminating between F1 and F2. Adjustment for bone density did not totally abolish the association between QUS parameters and vertebral fracture. Additionally, the combination of lumbar BMD and QUS ("stiffness") clearly showed a high power to discriminate NF from F1 + F2. In conclusion, we showed that QUS measurement is effective in evaluating fracture risk in advanced osteoporosis, while lumbar dual X-ray absorptiometry is effective in evaluating risk in early osteoporosis.

Aged↗
PubMed1999

Phase I/II study of weekly irinotecan and concurrent radiation therapy for locally advanced non-small cell lung cancer.

A study was undertaken to determine the maximum tolerated dose, the dose-limiting toxicities, and the response rate of irinotecan administered weekly with concurrent thoracic radiation therapy in patients with locally advanced non-small-cell lung cancer. In a phase I/II clinical trial, patients with histologically documented, surgically unresectable stage IIIA or IIIB non-small cell lung cancer (NSCLC) were enrolled. Irinotecan was administered as a 90 min intravenous infusion once weekly for 6 weeks. The starting dose was 30 mg m(-2) and dose escalation was done in 15 mg m(-2) increments. Dose-limiting toxicity was defined as grade 3 nonhaematologic toxicity (excluding nausea, vomiting and alopecia) or grade 4 haematologic toxicity according to the WHO criteria. Radiation was delivered to the primary tumour and regional lymph nodes (40 Gy), followed by a boost to the primary tumour (20 Gy). Twenty-seven patients were entered into this study at three irinotecan dose levels (30, 45 and 60 mg m(-2)). Twenty-six eligible patients were evaluated for toxic effects and clinical outcome. Severe oesophagitis, pneumonitis, and diarrhoea occurred at 45 and 60 mg m(-2). Three of the five patients given 60 mg m(-2) developed grade 3 or 4 oesophagitis and pneumonitis. In addition, one patient died of pneumonitis after completing therapy at 45 mg m(-2) in the phase II study. The objective response rate was 76.9% (95% CI, 53.0-88.9%). Oesophagitis, pneumonitis, and diarrhoea are the dose-limiting toxicities of weekly irinotecan combined with thoracic irradiation. The maximum tolerated dose and the dose for the phase II study were 60 and 45 mg m(-2) wk(-1), respectively. This combined therapy for locally advanced non-small cell lung cancer is promising and shows acceptable toxicity.

Adenocarcinoma↗
PubMed1999

Comparison of endoscopic features of early-stage squamous cell lung cancer and histological findings.

Seventy cases with early-stage central-type squamous cell carcinoma were treated surgically between 1984 and 1993 in seven participating institutes. We classified endoscopic features of early-stage central-type squamous cell carcinoma into three types (hypertrophic type, nodular type and polypoid type). After surgery we investigated the relationship between endoscopic features and both the area of superficial extent and depth of carcinoma invasion based on histopathological investigations of the surgical specimens. In 66.7% of the hypertrophic type lesions cancer cells did not invade into the cartilaginous layer, and only 4.8% of this type showed tumour invasion beyond the bronchial cartilage. On the other hand, a few nodular and polypoid type cases showed in-situ carcinoma or carcinoma with invasion from the subepithelial layer to the muscle layer, and in approximately 20% the these types we observed carcinoma invasion beyond the cartilaginous layer, which was not suitable for photodynamic therapy. Also, concerning the greatest dimension 24 out of 35 lesions (68.6%) less than 10 mm in the greatest dimension were evaluated as either in-situ carcinoma or micro-invasive tumour within the muscle layer. The endoscopic features can provide a basis for the determination of therapeutic strategy in early-stage central-type lung cancer.

Aged↗
PubMed1999

Retrovirus vectors designed for efficient transduction of cytotoxic or cytostatic genes.

It is difficult to establish stable packaging cell lines producing retrovirus vectors for the expression of anti-oncogenes with cytotoxic or cytostatic potential, because these genes would also affect the growth of the packaging cell lines. To overcome this problem, we designed a transcriptional unit pBabeLPL for vector RNA production, in which the transcription of the exogenous genes is completely suppressed by the presence of a preceding insertion containing the puromycin resistance gene (puro) and a poly(A) addition signal. This insertion is flanked by a tandem pair of loxP, and is designed to be excised after the introduction of Cre recombinase, when transcription of the exogenous gene will be started from the 5'-LTR. The transcriptional unit car- rying LacZ or p53 as the exogenous gene was introduced into a previously constructed prepackaging cell lines PtG-S2, in which the expression of VSV-G is also designed to be initiated by the introduction of Cre recombinase, while the gag-pol gene is expressed continuously. After the introduction of Cre recombinase by an adenovirus vector, LacZ- or p53-expressing VSV-G-pseudotyped retrovirus vectors with the designed structure were produced at high virus titers. The p53 virus was shown to be able to transduce p53 into the entire population of several human cancer cell lines and to induce their growth arrest at the G1 phase, indicating that this vector-producing system will be advantageous for human gene therapy.

Adenoviridae↗