Biomedical subjects

M Taniguchi

Publications and source records attributed to M Taniguchi.

At least 361 records · Page 20Linked to original sources

PubMed1997

Disruption of semaphorin III/D gene causes severe abnormality in peripheral nerve projection.

The molecules of the collapsin/semaphorin gene family have been thought to play an essential role in axon guidance during development. Semaphorin III/D is a member of this family, has been shown to repel dorsal root ganglion (DRG) axons in vitro, and has been implicated in the patterning of sensory afferents in the spinal cord. Although semaphorin III/D mRNA is expressed in a wide variety of neural and nonneural tissues in vivo, the role played by semaphorin III/D in regions other than the spinal cord is not known. Here, we show that mice homozygous for a targeted mutation in semaphorin III/D show severe abnormality in peripheral nerve projection. This abnormality is seen in the trigeminal, facial, vagus, accessory, and glossopharyngeal nerves but not in the oculomotor nerve. These results suggest that semaphorin III/D functions as a selective repellent in vivo.

Afferent Pathways↗

PubMed1997

Neuropilin-semaphorin III/D-mediated chemorepulsive signals play a crucial role in peripheral nerve projection in mice.

Neuropilin is a neuronal cell surface protein and has been shown to function as a receptor for a secreted protein, semaphorin III/D, that can induce neuronal growth cone collapse and repulsion of neurites in vitro. The roles of neuropilin in vivo, however, are unknown. Here, we report that neuropilin-deficient mutant mice produced by targeted disruption of the neuropilin gene show severe abnormalities in the trajectory of efferent fibers of the PNS. We also describe that neuropilin-deprived dorsal root ganglion neurons are perfectly protected from growth cone collapse elicited by semaphorin III/D. Our results indicate that neuropilin-semaphorin III/D-mediated chemorepulsive signals play a major role in guidance of PNS efferents.

Animals↗

PubMed1997

The role of mel-18, a mammalian Polycomb group gene, during IL-7-dependent proliferation of lymphocyte precursors.

mel-18 is a mammalian homolog of Drosophila melanogaster Polycomb group genes. Mice lacking the mel-18 gene show a posterior transformation of the axial skeleton, severe combined immunodeficiency, and a food-passing disturbance in the lower intestine due to hypertrophy of the smooth muscle layer. In this study, the severe combined immunodeficiency observed in mel-18 mutant mice is correlated with the impaired mitotic response of lymphocyte precursors upon interleukin-7 stimulation. Strikingly, the axial skeleton and lymphoid phenotypes are identical in both mel-18 and bmi-1 mutants, indicating that the Mel-18 and Bmi-1 gene products might act in the same genetic cascade. These results suggest that mammalian Polycomb group gene products are involved in cell cycle progression in the immune system.

Animals↗

PubMed1997

Epigallocatechin gallate-induced histamine release in patients with green tea-induced asthma.

BACKGROUND AND OBJECTIVE: Epigallocatechin gallate is the causative agent of green tea-induced asthma. To determine whether an IgE-mediated mechanism plays a pathogenetic role in this disorder, we measured histamine release after in vitro exposure to epigallocatechin gallate. METHODS: Subjects included eight patients (four men and four women) with green tea-induced asthma, who had been diagnosed by skin test and inhalation challenge, and eight controls (four asthmatic subjects with no previous exposure tea dust and four healthy volunteers). Heparinized whole blood samples were taken and incubated with epigallocatechin gallate at various concentrations (final concentration range, 0.003 to 300 micrograms/mL) for 30 minutes at 37 degrees C. After centrifugation, histamine was measured in the cell-free supernatants by radioimmunoassay. Histamine release was expressed as a percentage of total histamine. A result higher than 10% was considered positive. RESULTS: In one of the tea-sensitive patients, epigallocatechin gallate did not cause histamine release. Five of the other seven patients (71%) demonstrated a positive, dose-dependent histamine release to epigallocatechin gallate. In asthmatic and normal controls, histamine release was not observed at any epigallocatechin gallate concentration. Furthermore, a significant correlation was noted between the maximum percentage histamine release and the threshold epigallocatechin gallate concentration for intradermal skin testing. CONCLUSION: These results indicate that an IgE-mediated response is the basis for green tea-induced asthma.

Adult↗

PubMed1997

Long-term recording of olfactory and vomeronasal stimulant-induced waves from the turtle main olfactory bulb and accessory olfactory bulb.

Recording of stimulant-induced waves (bulbar responses) from the main olfactory bulb is a useful tool for measuring quantitative stable olfactory responses. There is a good relationship between the olfactory bulbar response, olfactory nerve response and electroolfactogram (EOG), suggesting that the bulbar response reflects events in receptor cells. The modern whole-cell recording technique offers direct information on olfactory transduction in single cells, but it requires long experimental periods and many animals. On the other hand, analysis of bulbar responses provides useful information and requires the use of few animals. For example, we found that cAMP-increasing and IP3-increasing odorants were not distinctly received by the turtle olfactory organ by measuring olfactory bulbar responses and analyzed with a multidimensional scaling from about 60 animals. However, to record similar odor responses from isolated turtle olfactory neurons, at least 200 animals would be necessary. Bulbar responses are recorded with electrodes implanted into or located on the main olfactory bulb. When electrodes are located on the olfactory bulb surface, it is possible to record stable responses over a period of 3 days. These methods were applied successfully to the accessory olfactory bulb. In this paper, we describe the protocols used for recording of the stimulant-induced waves from the main and accessory olfactory bulb.

Adaptation, Physiological↗

PubMed1997

Modulation of circadian expression of D-site binding protein by the schedule of parenteral nutrition in rat liver.

The aim of this study was to investigate the changes in the circadian rhythm of the expression of liver-specific genes caused by different schedules of parenteral nutrition (PN). Rats received PN continuously throughout the day or intermittently during the night or day for 7 days. They were examined for gene expression of D-site binding protein (DBP), albumin, and cytochrome P450 cholesterol 7alpha-hydroxylase (CYP7) in the liver. The nocturnal PN group showed circadian expression of DBP messenger RNA (mRNA) and protein with a peak at 10 PM, in the same manner as the control rats receiving normal chow feeding. However, the diurnal PN group showed inverted expression of DBP mRNA and protein with a peak at 10 AM. CYP7 mRNA levels exhibited good synchronization with the levels of DBP mRNA in all groups, whereas albumin mRNA levels did not show such synchronization. Gel mobility-shift assay disclosed that the binding activity of the nuclear extracts to the CYP7 gene promoter was changed by the PN schedule in accordance with the expression of CYP7 mRNA. The PN schedule modulates the circadian rhythm of DBP expression and may have an effect on hepatic bile acid formation through transcriptional regulation of the CYP7 gene.

Albumins↗

PubMed1997

Anterior skull base surgery for secondary malignancies in retinoblastoma survivors: report of two cases.

With the improved survival rate of patients with retinoblastoma, the incidence of second malignancies has become substantial. We had two retinoblastoma survivors with secondary malignancies in the naso-ethmoidal complex, one a 21-year-old man with anaplastic carcinoma and the other a 16-year-old girl with malignant fibrous histiocytoma. They underwent repeated craniofacial surgery. Secondary malignancies arising at the nose and ethmoidal cells often invade the anterior skull base. The introduction of skull base surgery has provided wider surgical margins and increased the resultant likelihood of cure. Both patients have so far shown no evidence of recurrence.

Case Reports↗

PubMed1997

Epidural anesthesia enhances sympathetic nerve activity in the unanesthetized segments in cats.

To evaluate compensatory sympathetic excitation during epidural anesthesia, we measured cardiac and renal sympathetic nerve activity during thoracic or lumbar epidural anesthesia in cats. Thirteen cats were divided into three groups: five cats received thoracic epidural anesthesia, five received lumbar epidural anesthesia, and three received lumbar epidural anesthesia after the carotid sinus and vagoaortic nerves were severed (denervated lumbar group). Heart rate (HR), mean arterial pressure (MAP), and cardiac and renal sympathetic nerve activity were measured repeatedly after administration of a single dose of 0.1 mL/kg of 1% lidocaine via the epidural catheter. Epidural solution spread from a median of C-8 to T-6 in the thoracic epidural group, T-8 to L-3 in the lumbar epidural group, and T-7 to L-3 in the denervated lumbar group. During thoracic epidural anesthesia, HR, MAP, and cardiac sympathetic nerve activity decreased, while renal nerve activity increased. Similarly, HR, MAP, and renal sympathetic nerve activity decreased during lumbar epidural anesthesia, and cardiac activity increased. In the denervated lumbar group, HR, MAP, and renal sympathetic nerve activity decreased but cardiac activity remained unchanged. Sympathetic nerve activity in corresponding unanesthetized segments increased during thoracic or lumbar epidural anesthesia in association with significant decreases in MAP and HR. After severance of the carotid sinus and vagoaortic nerves, the absence of sympathetic excitation in the unanesthetized segments during lumbar epidural anesthesia suggests that the compensatory response is produced by the baroreceptor reflex response to anesthesia-induced hypotension.

Anesthesia, Epidural↗

PubMed1997

Subtemporal keyhole approach to the suprasellar and petroclival region: microanatomic considerations and clinical application.

OBJECTIVE: To minimize surgical invasiveness, the keyhole concept is applied to the subtemporal approach. METHODS: Anatomic features were studied in 14 sides of adult cadaver heads, and the technique was used in 162 interventions. Although most of the lesions treated were 3 cm in size or smaller, larger lesions were also treated using this technique. In some cases, if needed, an endoscope-assisted microsurgical technique was used. RESULTS: The cadaveric study provided intimate experience with the microsurgical anatomy of the approach. The 162 consecutive patients who were operated on harbored various types of lesions; the most recent 43 consecutive interventions were investigated in detail. The complications encountered included five cases of permanent cranial nerve palsy, two cases of cerebrospinal leakage, two cases of short memory disturbance, two cases of seizure, and one case each of hemiplegia and incoordination, transient hearing loss and tinnitus, and consciousness deterioration and hemiplegia. CONCLUSION: With careful patient selection, the subtemporal keyhole approach diminishes tissue traumatization considerably and has proven to provide sufficient operating space in the suprasellar area. When this approach is combined with the cranial base technique, the petroclival region can also be treated. However, the subtemporal keyhole approach requires deliberate preoperative planning for each patient, as well as for each surgeon.

Adolescent↗

PubMed1997

Role of radiosurgery in the management of cavernous sinus meningiomas.

OBJECTIVE: To provide our early experience and philosophy in the utility of radiosurgery in the management of cavernous sinus meningiomas. METHODS: Twenty-five consecutive cases with cavernous sinus meningiomas treated between 1990 and 1995 were reviewed. Three cases were treated with gamma-knife radiosurgery, 15 with preceding surgery and gamma knife, 7 with surgery. Mean follow-up following radiosurgery and surgery were 34.8 and 25.4 months, respectively. RESULTS: The 5-year actuarial tumor control rate following radiosurgery was 85.7% and tumor remission rate was 61.4%. Permanent neurological deterioration after radiosurgery was seen in 1 case (5.9%), whereas newly developed or worsened neurological deficits permanently persisted in 59.1% of patients after surgery. There was a clear correlation between surgical radicality and postoperative morbidity rate. CONCLUSIONS: Gamma-knife radiosurgery is a valuable addition to surgical removal in the treatment of cavernous sinus meningiomas. Combination of non-radical resection and subsequent radiosurgery is recommended to improve treatment-associated morbidity.

Adult↗

PubMed1997

Early nonpolypoid colorectal cancer: radiographic diagnosis of depth of invasion.

PURPOSE: To diagnose depth of invasion of early flat and depressed nonpolypoid colorectal cancers with double-contrast barium enema examination. MATERIALS AND METHODS: Ninety-seven early nonpolypoid colorectal cancers, initially identified with colonoscopy, were investigated with double-contrast barium enema examination. Depth of invasion in resected specimens obtained with endoscopic mucosal or surgical resection was determined. Cancer confined to the mucosal layer or with focal extension to the submucosal layer was defined as Ca-m; moderate to massive extension of cancer into the submucosal layer was classified Ca-sm. RESULTS: In flat elevated and depressed cancers, converging folds and semilunar deformity were observed significantly more frequently in Ca-sm than in Ca-m tumors (P < .05 and P < .01, respectively). Sensitivities and specificities of these findings for Ca-sm tumor were 42%, 93% and 86%, 85%, respectively. Deep depression, irregular surface of the depression, and tumor size larger than 20 mm were also predictive findings for depressed Ca-sm tumors (P < .05); the specificity of each was 100%. With use of these radiographic predictors, overall accuracy for diagnosing depth of invasion was 85%. CONCLUSION: Findings on double-contrast barium enema study are highly predictive of depth of invasion of early nonpolypoid colorectal cancer. Radiographic findings of converging folds, semilunar deformity, deep depression, irregular surface of the depression, and tumor size are predictors of Ca-sm tumor.

Adult↗

PubMed1997

A case of favorable dilation of protected left main coronary artery lesion achieved through performance of adjunctive DCA on residual stenosis following use of rotablator.

It is believed that directional coronary atherectomy (DCA) is more suitable than percutaneous transluminal coronary angioplasty for lesions such as severe eccentric lesions, ostial lesions, and branch lesions. However, it remains a fact that lesions that are also highly calcified are often suboptimal, since there may be difficulties such as in insertion of the housing and in sufficient cutting and removal. On the other hand, Rotablator is effective on calcified lesions, but afterward, dilation by balloon angioplasty for residual stenosis becomes necessary in many cases. This is a report of the authors' experience on an interesting case in which favorable dilation of a lesion in the protected left main coronary artery (LMCA) was achieved by using Rotablator after confirmation of a high degree of calcification by means of intravascular ultrasound (IVUS) echocardiograhy, followed by the performance of DCA on the residual stenosis.

Angioplasty, Balloon↗

PubMed1997

Essential roles of the winged helix transcription factor MFH-1 in aortic arch patterning and skeletogenesis.

Mesenchyme Fork Head-1 (MFH-1) is a forkhead (also called winged helix) transcription factor defined by a common 100-amino acid DNA-binding domain. MFH-1 is expressed in non-notochordal mesoderm in the prospective trunk region and in cephalic neural-crest and cephalic mesoderm-derived mesenchymal cells in the prechordal region of early embryos. Subsequently, strong expression is localized in developing cartilaginous tissues, kidney and dorsal aortas. To investigate the developmental roles of MFH-1 during embryogenesis, mice lacking the MFH-1 locus were generated by targeted mutagenesis. MFH-1-deficient mice died embryonically and perinatally, and exhibited interrupted aortic arch and skeletal defects in the neurocranium and the vertebral column. Interruption of the aortic arch seen in the mutant mice was the same as in human congenital anomalies. These results suggest that MFH-1 has indispensable roles during the extensive remodeling of the aortic arch in neural-crest-derived cells and in skeletogenesis in cells derived from the neural crest and the mesoderm.

Animals↗

PubMed1997

Two cases of transiently TSBAb-positive hypothyroidism induced by interferon-alpha therapy for chronic hepatitis C.

A 34-year-old woman and a 54-year-old woman were treated with interferon-alpha (IFN-alpha) for chronic hepatitis C. Three months after the cessation of the IFN-alpha therapy, each patient developed hypothyroidism with the presence of thyroid-stimulation-blocking antibody (TSBAb) and TSH-binding inhibitor immunoglobulin (TBII). These two patients were treated with thyroxine, and both TSBAb and TBII activities gradually decreased. Although both TSBAb and TBII became negative several months after the start of the replacement therapy, the replacement dosage of L-thyroxine could not be reduced. Thyroid biopsies showed that the follicular epitheliums were flattened in both cases with lymphocytic infiltration. These findings suggest that IFN-alpha may induce hypothyroidism and the transient emergence of TSBAb and TBII.

Adult↗

PubMed1997

A pilot study of centrifugal leukocyte apheresis for corticosteroid-resistant active ulcerative colitis.

Corticosteroids are effective in bringing about a clinical remission in patients with ulcerative colitis. However, in severely relapsed cases, corticosteroids are not always effective even when a high dosage is administered. In addition, the long-term use of corticosteroids often causes serious side effects. Therefore, an alternative treatment for active ulcerative colitis is necessary in order to avoid these clinical problems. In the present pilot study, the efficacy of leukocytapheresis using a centrifugal procedure was evaluated for corticosteroid-resistant, active ulcerative colitis. Fourteen patients with corticosteroid-resistant severely active ulcerative colitis were treated by leukocytapheresis. Thirteen patients (92.9%) achieved clinical remission within 4 weeks after the apheresis, and remained in remission for 8 months on average without any additional corticosteroid therapy. In the remaining patient, in whom remission was not induced, a total colectomy was performed immediately after the fourth course of leukocytapheresis. No significant side effects were noticed throughout the therapy. Both colonoscopic and histological examinations confirmed the beneficial effect of this procedure in terms of the reduction of severe inflammation of the affected colon. We found that the expression of two adhesion molecules, L-selectin and VLA4a, on the surface of peripheral leukocytes was decreased after this new therapy.

Adrenal Cortex Hormones↗

PubMed1997

[Changes in tissue and blood polyamines during N-butyl-N-(4-hydroxybutyl) nitrosamine-induced bladder carcinogenesis in rats].

BACKGROUND: Polyamine are recognized as cell growth factors. We studied in order to determine whether alterations in the levels of tissue and blood polyamines were useful biochemical markers for bladder tumor. METHODS: The concentrations of three polyamines, diamine, spermidine and spermine, in urinary bladder and blood were determined during N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN)-induced bladder carcinogenesis in male F344 rats. At 5 weeks of age, rats were given 0.05% BBN in the drinking water for 20 weeks. RESULTS: BBN induced bladder hyperplasia in 4 of 5 rats at 8 weeks, papillomas in 2 of 5 rats at 12 weeks, and transitional cell carcinoma in all the rats by 20 weeks. The levels of total polyamine in both bladder and blood of the rats during 12-20 weeks were significantly higher than those of the control animals given water alone. The elevation of total polyamine was mainly due to the increase of spermidine of the three polyamines, which was coincident with the incidence of bladder tumors. CONCLUSION: The results indicated that the polyamines are excellent biochemical markers for bladder tumors.

Animals↗

PubMed1997

[Changes in tissue and blood polyamine levels following chemotherapy in rats with urinary bladder carcinoma induced by N-butyl-N-(4-hydroxybutyl) nitosamine in rats].

BACKGROUND: Polyamines are recognized as cell growth factors. We attempted to determine whether alterations in the levels of tissue and blood polyamines were useful biochemical makers for monitoring the efficacy of the chemotherapy for bladder tumors. METHODS: The concentrations of three polyamines of diamine, spermidine and spermine in urinary bladder and blood were determined in male F344 rats with urinary bladder carcinoma induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN), following chemotherapy with cisplatin, methotrexate and pirarubicin. RESULTS: Bladder carcinoma was observed in 5 of 20 rats of the chemotherapeutic group, and 16 of 20 rats of the control group given saline alone. The levels of spermidine, spermine and total polyamine in both bladder and blood of the treated rats were significantly lower than those of the control rats. CONCLUSION: The study suggested that the levels of tissue and blood polyamines could be used as biochemical markers for monitoring the efficacy of the chemotherapy for bladder tumors.

Animals↗

PubMed1997

The mode of action of UK-2A and UK-3A, novel antifungal antibiotics from Streptomyces sp. 517-02.

UK-2A and UK-3A are structural relatives of antimycins, which were isolated as antifungal antibiotics with little cytotoxicity that demonstrated inhibition of respiratory activity. They halve the cellular respiration of yeast within 4-5 minutes and the intracellular ATP content within 2-5 minutes. Moreover, they inhibited the yeast mitochondrial respiration using beta-hydroxybutyrate and succinate as a respiratory substrate, but no inhibition was observed using ascorbate-reduced tetramethyl p-phenylenediamine as the substrate. The site of respiratory inhibition of UK-2A and UK-3A was thought to be the cytochrome bc1 complex in the mitochondrial electron transport chain of yeast cells. They also inhibited the mitochondrial respiration of rat liver. It has been suggested that intact animal cells might have some system to defend themselves from the actions of UK-2A and UK-3A.

Adenosine Triphosphate↗