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Biomedical subjects

K Ichimura

Publications and source records attributed to K Ichimura.

At least 145 records · Page 8Linked to original sources
PubMed1993

[Surgical approach to the nasal valve stenosis].

Nasal valve, originally defined by Mink (1903), has changed its concept and is now regarded as slit-like opening between the caudal end of the upper lateral cartilage and the septum. Contrary to Caucasians whose smallest area of the nose lies at the nasal valve, the narrowest part of Japanese nose situates at the area between the anterior portion of the inferior turbinate and the septum. Thus, we have fewer chance to experience patients with stenotic nasal valve. Six patients complaining nasal obstruction resulted from nasal valve stenosis, mainly due to dislocated or collapsed upper lateral cartilage, underwent surgery during the last 2 years and a half. Cases of septal deformity, even it it produced valve stenosis, were excluded in this study. Surgical intervention was directed toward reconstruction of normal anatomic relationships, usually by widening the nasal valve angle and preventing collapsibility. Three underwent open rhinoplasty with gull-wing columellar skin incision, whereas 3 others were operated on via transnostril approach. History of midfacial trauma caused us to choose open rhinoplasty for restoring the function and structure. Immediate postoperative result was excellent in the aspect of appearance and subjective data regardless of surgical approach. Open rhinoplasty provided a splendid long-term result without remarkable complications. On the other hand, 2 cases operated via transnostril approach complained recurrence of stuffy nose.

Adult↗
PubMed1993

[Evidence for the presence of endothelium-derived relaxing factor in nasal blood vessels].

It has widely been recognized that the vascular endothelium plays an important role in the regulation of vascular tension. Endothelium-derived relaxing factor (EDRF) is a potent vasodilator produced by vascular endothelial cells in response to acetylcholine (ACh) and a variety of other substances. Recent studies have indicated its pharmacological and biochemical effect on vascular smooth muscle tension. The role of the vascular endothelium in the vasodilatory response to ACh stimulation was studied in isolated mucosa from the canine nasal fossa. (1) In the presence of intact endothelium, dose-dependent relaxation was induced by administration of ACh (10(-8)-10(-5)M) under sustained constriction by methoxamine. (2) After endothelial cell injury had been induced by administration of 15-hydroperoxyeicosa tetraenoic acid (15-HPETE), the relaxing response to ACh was abolished with the induction of contraction. (3) Pretreatment with a cyclo-oxygenase inhibitor (indomethacin) did not change the vasodilatory response to ACh stimulation. These results indicate that endothelium is necessary for relaxation in response to ACh, and suggest the presence of EDRF in vessels of the canine nasal mucosa.

Acetylcholine↗
PubMed1993

[Molecular biological analysis of neurofibromatosis type 2 gene].

Neurofibromatosis type 2 is a hereditary disorder characterized by bilateral vestibular and other schwannomas as well as various other central nervous system neoplasms such as gliomas, meningiomas, and neurofibromas. The region containing the NF2 gene has been localized to 22q12 both by linkage analysis and deletion mapping of NF2-related tumors. Recently a candidate gene, named Merlin, was cloned by means of defining a constitutional interstitial deletion in an NF2 patient. The Merlin gene product belongs to a family of proteins which include moesin, ezrin and radixin, involved in linking the cytoskeleton to the cell membrane. Merlin thus forms a novel class of tumor suppressor genes, and an analysis of its function in vivo and the clinical implications of its loss in schwannoma cells remains to be explored.

Cell Line↗
PubMed1993

Plasma endothelin-1 concentration in the inferior turbinate.

Endothelin (ET)-1 has the most potent vasocontrictive action of any substance known to date. Three milliliters of blood was removed from both the inferior turbinate and from the antecubital vein of six patients who underwent nasal surgery under general anesthesia. After centrifugation of the blood samples, the plasma was sent for radioimmunoassay of the plasma levels of ET-1. The plasma ET-1 level in the nasal blood vasculature was 6.4 +/- 1.0 pg/mL (mean +/- SEM), which was almost equivalent to that found in the antecubital vein (5.3 - 2.7 pg/mL) (N = 6). These values were greater than the normal range (1.5 +/- 0.5 pg/mL) probably because of the effect of general anesthesia. These results indicate that ET-1 is present in similar levels in the blood vessels of the inferior turbinate and the antecubital vein. A hypothesis that adrenaline induces ET production was not confirmed because topically applied adrenaline did not raise the plasma ET-1 level either in the nasal vasculature or in the peripheral vein.

Adult↗
PubMed1992

Constitutional translocation t(4;22) (q12;q12.2) associated with neurofibromatosis type 2.

We report on a female patient with bilateral acoustic neurinomas and other tumors in the central nervous system (neurofibromatosis type 2: NF2) and the constitutional translocation, t(4;22) (q12;q12.2). The precise identification of the translocation breakpoint (q12.2) on chromosome 22 implies the refined localization of a gene responsible for NF2, and would provide a clue to its molecular characterization and to the isolation of the gene. Chromosomes of a paraspinal neurinoma from the patient were also analyzed, and the same karyotype as seen in cultured peripheral lymphocytes was found. The patient's father was also a carrier of the translocation, but he had no clinical symptoms of NF2, nor did other relatives. Several explanations are offered for the different expression of the translocation between the patient and her father.

Adult↗
PubMed1992

Effects of inorganic iodide, epidermal growth factor and phorbol ester on hormone synthesis by porcine thyroid follicles cultured in suspension.

Porcine thyroid follicles cultured in suspension for 96 h synthesized and secreted thyroid hormones in the presence of thyrotropin (TSH). The secretion of newly synthesized hormones was assessed by determining the contents of thyroxine (T4) and triiodothyronine (T3) in the media and by paperchromatographic analysis of 125I-labelled hormones in the media where the follicles were cultured in the presence and absence of inhibitors of hormone synthesis. The hormone synthesis and secretion was modified by exogenously added NaI (0.1-100 microM). The maximal response was obtained at 1 microM. Thyroid peroxidase (TPO) activity in the cultured follicles with TSH for 96 h was dose-dependently inhibited by NaI. One hundred microM of NaI completely inhibited TSH-induced TPO activity. Moreover, both epidermal growth factor (EGF: 10(-9) and 10(-8) M) and phorbol 12-myristate 13-acetate (PMA: 10(-8) and 10(-7) M) inhibited de novo hormone synthesis. An induction of TPO activity by TSH was also inhibited by either agent. These data provide direct evidences that thyroid hormone synthesis is regulated by NaI as well as TSH at least in part via regulation of TPO activity and also that both EGF and PMA are inhibitory on thyroid hormone formation.

Animals↗
PubMed1992

Peritumoral cerebral edema in meningiomas: the role of the tumor-brain interface.

We investigated the role of the tumor-brain interface in the production of peritumoral cerebral edema in meningiomas by analysing the size, shape, histological type and location of the tumor, and radiological and operative findings. Our results suggest that changes of the boundary zone between the tumor and the brain such as the disappearance of the subarachnoid space, cortical thinning or loss, and possibly partial loss of the arachnoid membrane are the most important factors in edema production, and that multiple other factors determine the morphological changes which occur at the tumor-brain interface.

Adult↗
PubMed1992

Effects of epidermal growth factor, phorbol ester, and retinoic acid on hormone synthesis and morphology in porcine thyroid follicles cultured in collagen gel.

Epidermal growth factor (EGF), phorbol esters (PEs), and retinoic acid (RA) inhibit differentiated functions of thyrocytes. In the present study the inhibitory effects of these growth-promoting factors on hormone synthesis were studied in thyroid follicles cultured in type-I collagen gel, and morphologic alteration by these factors was examined by light and electron microscopy (EM). Porcine open thyroid follicles obtained by treatment with 0.1% collagenase were embedded in collagen gel and cultured in Ham's F12 medium supplemented with 6H (insulin, hydrocortisone, somatostatin, transferrin, glycyl-his-lys, and thyrotropin) + 0.5% fetal bovine serum (FBS). After 1 week these open follicles developed to closed follicles, and the medium was changed to one containing 6H + 0.5% FBS + 0.1 microM sodium iodide (NaI). Some media were supplemented with either EGF, phorbol 12-myristate 13-acetate (PMA), or all-trans RA. The closed follicles retained ability for hormone synthesis for 2 weeks after the medium change in the presence of 6H + FBS + NaI. The amounts of T4 and T3 secreted into the culture medium from day 9 to day 12 after the medium change were 60% and 45% of those from day 0 to day 4, respectively. EGF reduced production of T4 and T3 by 61% and 69%, respectively; PMA, by 87% and 99%; and RA, by 55% and 44%. In the medium supplemented with 6H + 0.5% FBS, the follicles exhibited intact polarity. Apical surfaces with microvilli were oriented to the follicular lumen and tight junctions were on the apical side of cell-to-cell contacts. Desmosomes were found on both the apical and basal halves of the cell contacts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[The effect of endothelin on neurotransmitter regulation of vascular tension in the nasal mucosa].

A number of studies have emphasized that the sympathetic nervous system in vascular smooth muscle plays an important role in the regulation of vascular tension. Recently, however, it has been suggested that several factors produced in endothelial cells may affect this regulatory mechanism. We have previously reported that endothelin-1 (ET), a novel potent endothelium-derived vasoconstrictor peptide, increased the contraction of nasal vascular smooth muscle which was caused by administration of noradrenaline (NA) into the bath solution. In this report, using canine nasal mucosa, we studied for additional effects of ET upon the vasoactivity of NA, and that of neuropeptide Y (NPY), which coexists with NA in the sympathetic nerve terminal. The results are as follows: 1) Pretreatment with alpha-adrenoceptor antagonists did not affect the vasoconstriction induced by ET. 2) With simultaneous administration of 10(-5)M NA and 10(-9)ET, the contraction peak was maintained for at least 2.5 hours. 3) Pretreatment with 10(-10)M ET did not affect the contraction induced by 2.7 x 10(-7)M NPY. 4) Pretreatment with 2.7 x 10(-8)M NPY did not affect the contraction induced by 10(-8)M ET. These results suggest that ET may enhance and prolong the vasocontractile response mediated by alpha-adrenoceptors, but may not affect the response to NPY.

Animals↗
PubMed1992

[Comparison of CT and MRI in diagnosis of parapharyngeal tumors].

Recently, the usefulness of CT and MRI in diagnosing parapharyngeal tumors has been established. At the same time, several modalities for these imagings, i.e. plane and enhanced CT, T1, 2 weighted MRI and Gadolinium enhanced MRI, have been developed. We compared the image findings of 12 tumors involving the parapharyngeal space with their operative records. T1 was most suited to diagnosing the sites of origins of tumors because of its superior depiction of the internal carotid artery and parapharyngeal fat. Enhanced CT was also superior in depicting these structures, but in cases where the parapharyngeal fat was diminished, or the parapharyngeal fat had been invaded by malignant tumor, enhanced CT was inferior to T1. The spatial resolution of T2 was poor, T2 was thus not useful in diagnosing the sites of origins of tumors. Because tumor intensity tended to be similar to that of fat in Gadolinium enhanced MRI imaging, Gadolinium was not as useful as T1. In diagnosing the extents of tumors, we examined the depiction of both tumor-fat and tumor-muscle interfaces. With regard to the depiction of the tumor-fat interface, enhanced CT and T1 were most useful. In diagnosing the tumor-muscle interface, Gadolinium enhanced MRI was most suitable. The net result is that MRI is superior to CT.

Adipose Tissue↗
PubMed1991

Asymmetric inclusion by de novo designed proteins: fluorescence probe studies on amphiphilic alpha-helix bundles.

The inclusion feature and supersecondary structure of the de novo designed proteins which are constructed with several amphiphilic alpha-helices and flexible linkage parts were investigated with fluorescence probes. Five types of small proteins (or peptides) have been designed, which are composed of 2, 3, 4, 4, and 6 helices, respectively, and are linked with only linear junctions except for one of 4-helix proteins. All of these proteins have inclusion ability for hydrophobic fluorophores. Further, by the analysis of fluorescence polarization anisotropy, it was suggested that these proteins include guest molecules in compact helix bundles constructed with about 4 helices. Asymmetric inclusion of both monomer and stacked dimer of acridine orange derivatives was found by means of induced circular dichroism except for the 4-helix protein with cross-junction. The chirality of the included dimer proved to be in accordance with the chiral sense of alpha-helical coiled-coil. The 6-helix protein has especially high efficiency in inclusion for any fluorophores examined in this study and brings about a significant blue-shift of maximal emission for 8-anilino-1-naphthalenesulfonate.

Acridine Orange↗
PubMed1991

Cell culture of the intervertebral disc of rats: factors influencing culture, proteoglycan, collagen, and deoxyribonucleic acid synthesis.

To establish cell culture of the nucleus pulposus and anulus fibrosus of rat intervertebral disc, the effects of culture conditions on the growth of cells and the synthesis of DNA, proteoglycan, and collagen were studied. For cell culture of the nucleus pulposus, the use of 3-week-old rats and a medium adjusted to pH 7.0 was optimal. There was almost no difference in growth between cells in Ham's F12 medium and those in Dulbecco's Modified Eagle Medium. In cells isolated from the anulus fibrosus, a medium adjusted to pH 7.0-7.6 was preferable, but irrespective of rat age. Culture cells of the nucleus pulposus were composed of large cells with vacuoles and small polygonal cells. These cells had a slight growth activity and a fair capability of proteoglycan and collagen synthesis. Culture cells of the anulus fibrosus were composed of polygonal and spindle-shape cells, and the growth was more vigorous with the potentials for proteoglycan and collagen synthesis than the nucleus cells.

Age Factors↗
PubMed1991

[Isolated medial orbital wall fracture and late fronto-ethmoidal mucocele].

Twenty-one cases of isolated medial orbital wall fractures were reported and CT findings by coronal planes were evaluated as to the effects of fractures upon the ethmoidal cells and nasal meati. Three coronal planes, which respectively contain such structures as Agger nasi, Pars membranacea and superior meatus, were selected for the study. The extent of fracture was evaluated by dividing the medial wall into three equal portions, i.e., superior, middle and inferior. The prolapsed volume was evaluated in three classes of occupying 1/3, 2/3 and 3/3 of the ethmoid. The presence of soft tissue density was recorded at the three surfaces, upper, medial and lower, around the prolapsed orbital content. The extent of the fracture was most often seen in such cases as involving all the three divisions in 41.3%. The prolapsed volume occupying 1/3 was seen in 28, 6%, and 2/3 in 23.8%. The presence of soft tissue density was seen in 38.1% of upper surface, in 36.5% of medial, and 11.1% of lower. Summarizing the total effects of the fractures, the coronal plane containing Pars membranacea was most severely damaged followed by the plane of the superior meatus. Two rare cases of fronto-ethmoidal mucoceles, caused by the traumas of 23 and 14 years before respectively, were also included and reported. The ophthalmological prognosis was favorable in 90.5% of cases by observations extending more than 6 months. Five cases were surgically treated including two cases of mucoceles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[The vasoactivity of endothelin in the nasal mucosa].

Endothelin (ET), a novel endothelium-derived vasoconstrictor peptide with 21 amino acid residues, has recently been isolated from the supernatant of cultured porcine aortic endothelial cells. Several authors reported preliminary results demonstrating that ET has a potent contractile action in vascular smooth muscles, but its effect is slightly different in each target tissue. In the present study, we have examined the vasoactivity of ET in human and canine nasal mucosa with in vitro bioassay. The results are as follows. 1) ET induced a slow, and very sustained contraction from 10(-9) M. This response is stronger than that of noradrenaline (NA) and continued for 6-12 hours. 2) Under the sustained contraction by the administration of alpha 1 adrenoceptor agonist (methoxamine), ET induced an additional contractile response. 3) The response of ET depended on the concentration of Ca2+. 4) ET did not affect the contraction of vascular smooth muscle which was caused by the electrical stimulation. 5) ET increased the contraction of vascular smooth muscle which was caused by the administration of NA into the bath solution.

Amino Acid Sequence↗
PubMed1991

[Anatomical study on the sphenoidal sinus and petrous apex cells].

Morphological relation between the sphenoidal sinus and the petrous apex cell was studied using HRCT images obtained by 339 adults and 43 infants. The adults were classified into normal group (without chronic otitis media or its surgery) 237 cases, and otitis group (chronic otitis media or its post. op.), 102 cases. The posterior extent of the sphenoidal sinus was evaluated in reference to the carotid canal, and the petrous apex cells were evaluated by their mode of distribution in the apex. In the normal adults, no evident relation was seen between the posterior extent and the mode of distribution. Although adult normal female showed statistically significant better development of the posterior extent, sinus-cell relation was similar between both sexes. The adult normal group and otitis group behave similarly by sinus-cell relation, i.e., no evident relation, although inhibited mode of distribution was seen by otitis group. When the adult and infant were compared, the sinus-cell relation was similar and the posterior extent suffered underdevelopment by infant. The distance, between the posterior extension of the sphenoidal sinus and the apex cell at the medial-anterior tip of the petrous bone, is between 8-16 mm and the contact of the both separated by thin bony wall (less than 0.5 mm) was seen in 3 adult cases (0.9%). Both the sphenoidal sinus and the petrous apex cells are under genetic influence of variable degree, separate genes seem to be at work, thus effecting no evident relation between the two. Apart from the internal or genetic influence, environmental or outer influence also affects the development of the two, less than the genetic.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Measurement of parapharyngeal space using CT images].

Parapharyngeal space can be defined as a potential space surrounded by deglutitional and masticator muscles and their covering, superficial and middle layer of deep cervical fascia. It is easily recognized in images provided by modern scanning devices, such as CT and MRI. Parapharyngeal space has traditionally been divided by styloid process and fascia of tensor veli palatini muscle (nasopharyngeal level) or fascia of stylopharyngeus muscle (oropharyngeal level) into two compartments, prestyloid and postsyloid spaces. The latter is often called as carotid space. Prestyloid portion exclusively contains fat tissue, which yields hypoabsorption area in CT films and high density area in MRI. In most of papers in radiological journals, the term of parapharyngeal space is regarded as its prestyloid portion which is clearly identified. Axial CT images of 144 patients without any naso- or oropharyngeal lesions were analyzed. Two reference levels of nasopharynx were adopted for the study. The upper level passes through the plane of fossa of Rosenmuller, and the lower reference level transects soft palate. The following parameters of the space were measured; Length and width of the whole space, length and width of prestyloid fatty space, and furthermore, width of pre- and poststyloid space, that were divided by a imaginary line parallel to the axis of the whole space (the upper level); Length and width of the whole space, length of base and height of a triangle of the prestyloid part (the lower level). While parapharyngeal space was symmetrical in the upper level, the rate of asymmetry amounted to a fourth in the lower level.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗