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Biomedical subjects

K Ichimura

Publications and source records attributed to K Ichimura.

At least 109 records · Page 6Linked to original sources
PubMed1996

Auditory brainstem responses in infants and children with anoxic brain damage due to near-suffocation or near-drowning.

We studied auditory brainstem responses (ABRs) of sixteen infants and children with brain damage after anoxic accidents due to near-suffocation or near-drowning. The patients manifested cerebral palsy, mental retardation and/or epilepsy and showed poor responses in the behavioral audiometry. Auditory brainstem responses were abnormal in five of the patients in the near-drowning group (waves I, II and III only were present in three patients and the amplitudes of waves IV and V were low in two patients) but normal in most of the patients in the near-suffocation group. This difference in the ABRs between the two groups suggest that in infants and children anoxic brain damage due to near-drowning might involve not only the cerebral cortex and subcortical white matter but also the upper brainstem and midbrain.

Brain Injuries↗
PubMed1996

Effect of new macrolide roxithromycin upon nasal polyps associated with chronic sinusitis.

We often observe shrinkage of nasal polyps with low-dose long-term macrolide treatment, which was recently developed in Japan for the treatment of intractable chronic sinusitis. In order to assess the efficacy of this treatment for nasal polyps, we administered the new macrolide roxithromycin (RXM) (1 tablet: 150 mg a day) for at least 8 weeks to 20 patients with nasal polyps associated with chronic sinusitis. It was competent in controlling nasal polyp with the overall incidence of improvement being 52%. The combination of RXM with azelastine (1 mg twice/day), an inhibitor of mediator release, was examined in 20 other patients. It augmented the rate of improvement to 68%, but the increase was not significant. The incidence of improvement increased with time after the start of medication in both groups. Smaller polyps were more likely to decrease in size, but some larger polyps also markedly decreased in size. Associated allergic conditions and the extent of eosinophilic infiltration had no relation to the treatment result. We speculate that the mechanism of effectiveness of RXM is through its suppressive potency in cytokine production from inflammatory cells.

Adult↗
PubMed1996

Surgical management of the plunging ranula: a review of seven cases.

We have treated seven patients with a plunging ranula during the past 10 years. All patients underwent surgery via a cervical approach. In two, the ranula reached the anterior neck by passing through a dehiscence in the mylohyoid muscle, while in the other five the plunging ranula passed posteriorly to the mylohyoid muscle. A pseudocyst was extirpated in each patient. Although total sublingual gland excision was not performed in two patients, no recurrence was observed in any patient. Incision of the pseudocyst facilitated subsequent procedures and decreased the incidence of transient facial paralysis. In the presence of a cervical mass without swelling of the oral floor, a cervical approach may still be the method of choice either for the first operation or for salvage surgery after recurrence subsequent to intraoral procedures. It is based on the fact that there may be ectopic sublingual glands residing on the inferior surface of the mylohyoid muscle.

Adolescent↗
PubMed1996

Ontogenic changes in the expression of cytochrome c oxidase subunit I gene in the cerebellar cortex of the perinatal hypothyroid rat.

The thyroid hormone plays a critical role in normal development of the mammalian central nervous system. This study was designed to examine the effect of perinatal hypothyroidism on ontogenic change in cytochrome c oxidase subunit I (COX I) gene expression in the rat cerebellum by using quantitative in situ hybridization histochemistry (ISH). Newborn rats were rendered hypothyroid by continuous administration of methimazole in the mothers' drinking water. The pups were then killed by decapitation on 1, 5, 10, 15, 20, and 30 days after birth (P1, P5, P10, P15, P20, and P30). Their cerebella were removed, and frozen sections were cut and processed for ISH with 35S-labeled RNA probe for COX I messenger RNA. After hybridization, emulsion autoradiography was performed. The numbers of grains within the external granule cell layer, molecular layer, and internal granule cell layer were then counted. A significant decrease in grain density was detected in the hypothyroid animal in all these areas on P5, P10, and P15. On P15, in the molecular layer, a greater hybridization signal was detected in the inner portion than in the outer portion in the euthyroid animal. No such difference was seen in the hypothyroid animal. Daily T4 treatment for 15 days restored the effect of methimazole treatment. The significant effect of perinatal hypothyroidism on COX I gene expression was not detected after P20. These results indicate that altered thyroid states affect the COX I gene expression in the cerebellar cortex during development, suggesting that the COX I gene is one of the key genes regulated by the thyroid hormone and plays an important role in the morphogenetic changes observed in the perinatal hypothyroid cerebellum.

Aging↗
PubMed1996

[Investigation of "anosmic zones" associated with nasal allergy].

Twenty-seven nasal allergy patients suffering from olfactory disturbance were evaluated in this study. The intravenous olfaction test yielded almost normal responses in 27 cases. The standard olfactory acuity test, however, showed that the mean thresholds of detection of each odor were almost the same, while the mean thresholds of recognition of odors A and E were higher than those of the other odors. Douek has reported selective olfactory loss in patients with vasomotor rhinitis including allergic rhinitis and proposed the concept of "anosmic zones". By modifying the definition of "anosmic zones" in order to use it for the results of T & T olfactometry, we identified 8 patients who exhibited anosmic zones among 27 subjects. These results were inconsistent with the proposed mechanism that nasal obstruction causes olfactory disturbance in patients suffering from nasal allergy. Therefore, the specific factors related to nasal allergy may influence olfaction. We speculate that the pathological changes in the olfactory mucosa may induce secondary abnormalities in olfactory transduction, particularly at the point of signal transduction in olfactory cells. Other possibilities to explain anosmic zones were also discussed.

Adolescent↗
PubMed1996

Epidermal growth factor receptor expression in oligodendroglial tumors.

A series of 13 oligodendrogliomas (WHO grade II) and 20 anaplastic oligodendrogliomas (WHO grade III) was studied for gene amplification and expression of the epidermal growth factor receptor gene (EGFR). EGFR gene amplification was found in only one case of anaplastic oligodendroglioma, which additionally showed a deletion/rearrangement at the 5' end of the gene. Northern blot analysis, however, revealed increases of EGFR mRNA expression relative to non-neoplastic control brain in 6 of 13 oligodendrogliomas and 10 of 18 anaplastic oligodendrogliomas. All cases with increased mRNA expression showed strong immunoreactivity for EGFR protein. Our findings thus indicate that increased expression of EGFR mRNA and protein is common in low-grade and high-grade oligodendroglial tumors and in the vast majority of cases is not caused by gene amplification.

Adolescent↗
PubMed1996

[A case of middle cranial fossa meningioma extending into the infratemporal fossa: an approach to the pterygoid extension of the sphenoid sinus via the infratemporal fossa].

A case of middle cranial fossa meningioma extending into infratemporal fossa and the pterygoid process is presented. The patient had a sphenoid sinus extending inferolaterally into the pterygoid process, which is known as pterygoid extension of the sphenoid sinus. This type of variation of the sphenoid sinus allowed a safe and well-oriented approach to the pterygoid process via the infratemporal fossa. The tumor extending into the pterygoid process was removed successfully without damaging any surrounding structures, e.g. maxillary nerve or Vidian nerve. However, pterygoid extension of the sinus is seen in only 40% of cases. Therefore, close preoperative examination with bone window CT scan is mandatory before employing this approach.

Cranial Fossa, Posterior↗
PubMed1996

Free colon transfer: a versatile method for reconstruction of pharyngoesophageal defects with a large pharyngostoma.

Free transverse colon transfers based on the middle colic vessels were used to reconstruct a pharyngoesophageal defect in 9 patients. In all patients, cancer invaded up to the oropharynx. Resection resulted in a larger pharyngostoma than normally seen following standard total pharyngolaryngoesophagectomy. In such cases, it can be difficult to achieve good swallowing function after reconstruction using the free jejunal transfer. This mainly results from a significant discrepancy between the diameter of the pharyngostoma and that of the jejunum. Compared to the jejunum, the transverse colon has a larger diameter with a longer vascular pedicle and can provide a longer, straight intestinal tube, facilitating easy passage of a food bolus. In our series, all transfers survived well and all patients had good swallowing function postoperatively. We consider that a free colon transfer is more suitable than a free jejunal transfer for pharyngoesophageal reconstruction in patients with a large pharyngostoma.

Aged↗
PubMed1995

Amplification at 12q13-14 in human malignant gliomas is frequently accompanied by loss of heterozygosity at loci proximal and distal to the amplification site.

We have recently reported that a subset of human malignant gliomas shows amplification and overexpression of multiple genes from chromosomal segment 12q13-14, including CDK4, SAS, and MDM2. In the present study we have performed an allelotyping for 16 polymorphic loci spanning both arms of chromosome 12 in a series of 136 gliomas. Allelic deletions were found in 50% (7 of 14) of the malignant gliomas with 12q13-14 amplification and involved loci located on 12q proximal and distal to the amplification site. In contrast, the incidence of allelic loss on chromosome 12 was significantly lower in gliomas without 12q13-14 amplification [14% (11 of 79) in the WHO grade III and IV gliomas, 9% (4 of 43) in the WHO grade I and II gliomas]. The frequent association between 12q13-14 amplification and loss of alleles from 12q is in line with a model suggesting chromosome breakage and deletion as important events in the development of gene amplification.

Alleles↗
PubMed1995

Essentials of surgical treatment for intramasseteric hemangioma.

Although rare, surgical treatment may become necessary for patients with intramasseteric hemangiomas. Possible bleeding, neural injury or postoperative dysfunction are factors limiting surgical approaches. We present the following surgical highpoints for tumors involving the masseter muscles. These include careful preoperative planning with computed tomography and magnetic resonance imaging, as well as a surgical approach that provides adequate exposure for optimal tumor resection and identification of vital anatomic structures. In particular, care must be taken to preserve branches of the facial nerve. In certain cases, preoperative embolization or ligation of vessels feeding tumor helps to minimize blood loss. Whenever possible, complete tumor should be adequately resected with a surrounding margin of normal muscle. Postoperative lymphedema can be minimized by preserving the mandibular periosteum and oral or parenteral use of medication with anti-inflammatory agents. At the University of Tokyo, continuous suction is preferred with a fenestrated drain or pressure dressing with a Penrose drain should be applied to prevent hematoma. Postoperative dysfunction, such as trismus, is prevented by supportive measures.

Adult↗
PubMed1995

Solution X-ray scattering study on the chaperonin GroEL from Escherichia coli.

The molecular architecture of native GroEL has been studied by solution X-ray scattering. The radius of gyration for the native molecule was estimated to be 66.0 A in 50 mM Tris-HCl, 100 mM KCl at pH 7.5 and 25 degrees C. The maximum dimension was estimated to be 170 A, based on the pair distance distribution function. A cylindrical structure or two heptameric rings was found to be the best for native GroEL among structures examined by using a multi-sphere model analysis in which the radius of constituent sphere was 6 A. The results of the model analysis show that the radius of GroEL is 68.0 A and the height is 150.7 A. Unexpectedly, the central penetrating hole through GroEL was not confirmed in the best-fit structure.

Chaperonin 60↗
PubMed1995

Effect of perinatal hypothyroidism on expression of cytochrome c oxidase subunit I gene, which is cloned by differential plaque screening from the cerebellum of newborn rat.

Early development of the central nervous system is influenced by several hormones including thyroid hormone. This study was designed to clone the gene whose expression is changed in association with perinatal hypothyroidism in the rat cerebellum. Rats were sacrificed at 15 day-old postnatal age (P15) and their cerebella were removed. Poly (A)+ RNA was extracted to construct a cDNA library using lambda gt 10 cloning vector. Differential plaque screening was then performed using 32P-labeled antisense cDNA synthesized from poly (A)+ RNA of the methimazole-treated (hypothyroid) P15 rat cerebellum (hypothyroid probe), and of the euthyroid P15 rat cerebellum (euthyroid probe). The clones, which hybridized strongly to the euthyroid probe and weakly or not at all to the hypothyroid probe, were isolated. Sequence analysis of these clones revealed that all isolated clones encode cytochrome c oxidase subunit I (COX I), which is located in the mitochondrial DNA. The decrease in COX I gene expression was not seen in the animals, which received methimazole treatment and daily replacement of thyroid hormone. In situ hybridization detection showed not only overall decrease in COX I gene expression but also change in distribution of hybridization signal in the cerebellar cortex of hypothyroid rat. Such change was not observed in the T4-replaced animals. Based on the evidence that thyroid hormone greatly influences brain development, the results of the present study indicate that the terminal enzyme of mitochondrial respiratory chain, COX I is one of the important target molecules regulated by thyroid hormone in the newborn rat cerebellum.

Animals↗
PubMed1995

[A case of palatal polymorphous low grade adenocarcinoma].

We present a 58-year-old male patient with bilateral cheek swelling and an extraorally protruding tumor who has had deaf mutism since birth. He underwent surgery of the right hard palate 11 years ago. Five years later biopsy was performed for a recurrent lesion diagnosed as pleomorphic adenoma. He refused additional treatment and the size of the tumor subsequently increased slowly. As rapid tumor-growth had been observed since autumn of 1992, he was referred to Tokyo University Hospital. We took meticulous care of this deaf-mute patient, especially from the psychological aspect, which caused him to place great reliance upon us. We performed bilateral maxillectomy with partial resection of the right cheek skin and reconstructed his face and palate successfully using both latissmus dorsi and serratus anterior musculocutaneous free flaps with a rib. Histopathological diagnosis of the tumor was polymorphous low grade adenocarcinoma, which was registered as a definite entity in the WHO Classification in 1991. There was no evidence of local recurrence or metastasis one year postoperatively.

Adenocarcinoma↗
PubMed1994

CDKN2 (p16/MTS1) gene deletion or CDK4 amplification occurs in the majority of glioblastomas.

Forty-six glioblastomas, 16 anaplastic astrocytomas, and 8 astrocytomas were studied for the loss of the CDKN2 (p16/MTS1) gene on 9p. The CDKN2 locus was homozygously deleted in 19 of 46 glioblastomas (41%) and 1 allele was lost in an additional 13 cases (28%). The deleted regions were limited centromerically in some cases by the MTS2 locus and telomerically by the 1063.7 locus. CDKN2 was homozygously deleted in 3 of 16 anaplastic astrocytomas (19%) and 2 further cases showed loss of 1 allele. Amplification of the CDK4 gene was present in 7 of 14 (50%) glioblastomas and 3 of 11 (27%) anaplastic astrocytomas with no losses at the CDKN2 locus as well as in 2 of 32 (6%) glioblastomas with CDKN2 losses. Thus one or more of these two genes were shown to be aberrant in 85% of glioblastomas and 50% of anaplastic astrocytomas. None of the 8 astrocytomas showed abnormalities of these genes.

Alleles↗
PubMed1994

Amplification of multiple genes from chromosomal region 12q13-14 in human malignant gliomas: preliminary mapping of the amplicons shows preferential involvement of CDK4, SAS, and MDM2.

We have investigated 234 tumors of the central nervous system for amplification of 9 different loci from 12q13-14 and report that about 15% of the anaplastic astrocytomas and glioblastomas show amplification at this chromosomal region. The genes most frequently amplified were CDK4 and SAS (18 of 19 cases). MDM2 was coamplified with CDK4 and SAS in 11 tumors while one glioblastoma showed only MDM2 amplification. Some amplicons additionally included GADD153 (9 cases), GLI (6 cases), A2MR (3 cases), and the anonymous locus D12S8 (2 cases). Either MDM2 or CDK4 and SAS showed the highest amplification level in each individual amplicon and amplification of these genes was consistently accompanied by strong overexpression. Our results thus suggest CDK4, SAS, and MDM2 as main targets for the amplification; however, the possibility exists that all amplicons share a common amplified region between MDM2 and CDK4/SAS which might contain one or more as yet unidentified genes.

Astrocytoma↗
PubMed1994

A common region of homozygous deletion in malignant human gliomas lies between the IFN alpha/omega gene cluster and the D9S171 locus.

Deletions of the 9p-localized type-I interferon (IFN) genes and adjacent loci often occur during the development of malignant glioma. We have applied restriction fragment length polymorphism and microsatellite analysis to 12 loci covering this region of 9p and 3 loci on 9q in 74 human glial tumor tissues to define and further localize the smallest region of hemizygous or homozygous deletion common to the tumors. Three regions of homozygous deletion were evident among the panel of tumors; only one of these, however, residing between D9S171 and the IFN alpha/omega gene cluster, was involved in multiple cases (13 glioblastomas). Hemizygous deletion of this same region was observed in an additional 27 tumors. In total these data indicate the frequent inactivation of a novel tumor suppressor gene residing adjacent to and centromeric of the type-I IFN genes in malignant gliomas.

Alleles↗