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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
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↗
PubMed1991

[Standardization of definitions concerning smoking behavior among Japanese adolescents--results from the Japan Adolescent Smoking Survey (JASS)].

The aim of the Japan Adolescent Smoking Survey (JASS) is to standardize the definitions of smoking behavior among Japanese adolescents together with measurement methods and questionnaires concerned. A study of 9921 school children aged 9 to 18 years in 17 elementary schools, 16 junior high schools and 18 senior high schools in 9 prefectures, was conducted between June and July of 1989, to determine the relationship between actual smoking behavior during the past month or year and the "self-referent label" concerning their smoking status. The main results were as follows: 1) The percentage of those who smoked at least one cigarette during the past month showed a high degree of similarity to the percentage of those who referred to themselves as "regular smokers" or "occasional smokers". 2) Less than 10% of students who identified themselves as "never smokers" or "ex-smokers" smoked at least one cigarette during the past month, while more than 80% of students who referred to themselves as "regular smokers" or "occasional smokers" smoked during the past month. 3) On the whole, those who smoked 20 or more cigarettes during the past month referred to themselves as "regular smokers"; those who smoked between 2 and 19 cigarettes as "occasional smokers"; those who smoked 1 cigarette as "ex-smokers"; those who did not smoke during the past month as "never smokers". 4) The definition where students who smoked one cigarette during the past month are classified as a category of smoker, displayed a high level of sensitivity and specificity for all school-level groups and for both sexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Dentigerous cyst of the maxilla and its image diagnosis.

Dentigerous cysts may grow unnoticed to such extensive sizes as to occupy a considerable portion of the maxillary sinus. As they enlarge, the bony walls overlying the cysts thin out giving rise to an egg shell sensation upon palpation. Three cases of such extensive dentigerous cysts were experienced since 1987. These three cases were used to illustrate the advantages and disadvantages of the following imaging techniques in the preoperative evaluation of these cysts, conventional radiographs, sonography, CT, and MRI.

Adult↗
PubMed1991

[Smoking and alcohol drinking behavior among Japanese adolescents--results from "Japan Know Your Body Study"].

The "Japan Know Your Body Study" (JKYB) is an example of collaborative activities of technology transfer carried out in Japan in several phases. The first phase is a needs assessment and data collection survey and it was administered during 1989. A survey was conducted throughout 9 prefectures in Japan with participation by 49 schools. Subjects were students in elementary, junior and senior high schools who ranged in age from 6 to 18 years. Participants, 12,892 in total, completed a survey on knowledge, attitude and behavior regarding cigarette smoking, alcohol drinking, diet, exercise and so on. The main results concerning cigarette smoking and alcohol drinking behavior were as follows: 1) The percentage of monthly male smokers rose remarkably from 8% in the third grade of junior high school to 37% in the third grade of senior high school, while that of female smokers showed a slow rise from 3% to 15%. The sex difference for smoking behavior was clear among senior high school students. 2) Smoking rates increased in proportion to the numbers of parents, siblings and friends who smoked. Above all, smoking behavior of friends was strongly related. Among senior high school students, for example, 50% of males and 46% of females who had two or more smoking friends were smokers, as compared to 5% of males and 2% of females with no smoking friends. 3) The percentage of monthly drinkers rose at a steady pace from 13% of males and 7% of females in the fifth grade of elementary schools to 59% of males and 50% of females in the third grade of senior high schools. The sex difference for alcohol drinking behavior among senior high school students, while statistically significant, was not as pronounced as that for smoking behavior. These results suggest that tobacco- and alcohol-use prevention programs should be introduced in elementary schools and those programs should include components relating to the social influences of parents, siblings and friends.

Adolescent↗
PubMed1991

Vasoactivity of endothelin in nasal blood vessels.

Endothelin (ET) is a newly described peptide that was isolated from the supernatant of cultured porcine aortic endothelial cells. Among the three isoforms of ET, the originally discovered ET-1 is the only one that exists in vascular endothelium. It is reported to be an extremely potent vasoconstrictor in a variety of blood vessels. Using in vitro bioassay technique, the vasoactivity of ET-1 in both canine and human nasal mucosa was investigated. ET produces a contraction which is slow in onset and sustained in the blood vessels both of the canine and the human nasal mucosa. The threshold of ET-1 in causing contraction was 10(-9) M (dog) and 10(-8) M (human). This response was turned out to be extracellular Ca(2+)-dependent, because either Ca(2+)-free medium or application of nifedipine almost abolished it. A subthreshold concentration of ET-1 enhances exogenously applied noradrenaline (NA)-induced contractions, but not endogenous NA-induced contractions caused by transmural electrical stimulation. As endothelium derived substances, such as ET-1 showed strong vasoactivity, endothelium may play an important role in maintaining vascular tension of the nasal blood vessels along with neural control.

Animals↗
PubMed1990

Binding of Cu(II), Tb(III) and Fe(III) to chicken ovotransferrin. A kinetic study.

The kinetics of binding of Cu(II), Tb(III) and Fe(III) to ovotransferrin have been investigated using the stopped-flow technique. Rate constants for the second-order reaction, k+, were determined by monitoring the absorbance change upon formation of the metal-transferrin complex in time range of milliseconds to seconds. The N and C sites appeared to bind a particular metal ion with the same rate; thus, average formation rate constants k+ (average) were 2.4 x 10(4) M-1 s-1 and 8.3 x 10(4) M-1 s-1 for Cu(II) and Tb(III) respectively. Site preference (N site for Cu(II) and C site for Tb(III] is then mainly due to the difference in dissociation rate constant for the metals. Fe(III) binding from Fe-nitrilotriacetate complex to apo-ovotransferrin was found to be more rapid, giving an average formation rate constant k+ (average) of 5 x 10(5) M-1 s-1, which was followed by a slow increase in absorbance at 465 nm. This slow process has an apparent rate constant in the range 3 s-1 to 0.5 s-1, depending upon the degree of Fe(III) saturation. The variation in the rate of the second phase is thought to reflect the difference in the rate of a conformational change for monoferric and diferric ovotransferrins. Monoferric ovotransferrin changes its conformation more rapidly (3.4 s-1) than diferric ovotransferrin (0.52 s-1). A further absorbance decrease was observed over a period of several minutes; this could be assigned to release of NTA from the complex, as suggested by Honda et al. (1980).

Animals↗
PubMed1990

Cavernous angioma with encapsulated intracerebral hematoma: report of two cases.

Two cases of a cavernous angioma with an encapsulated intracerebral hematoma are presented. In both instances, computed tomography scan showed a ringlike appearance with a nodular lesion. Cerebral angiograms of the two cases, however, were normal. The preoperative diagnosis for both cases was a brain neoplasm. The diagnostic problems that this type of vascular malformation presents and its role in the development of the encapsulated hematoma are discussed.

Adult↗
PubMed1990

[Relationship between development of periodontitis and macrophage's defensive power against infection in rats fed a high-sucrose diet].

As mononuclear phagocytes have been implicated as important cellular elements in the process of bone resorption, we decided to study the relevancy of macrophage (M phi) activities to bone resorption. In this study, we investigated the phagocytic activity and activities of lysosomal enzymes of peritoneal resident M phi from rats fed a high-sucrose diet (Diet 2000) to appreciate the effects of Diet 2000 on systemic and local factors. Minkin et al. have postulated that bone-derived chemotactic factors were released from foci undergoing resorption. And so, we examined the effects of the supernatant from alveolar bone cultures (Bone-sup) prepared from rats fed Diet 2000 on the activities of glycogen induced peritoneal M phi. As a result we observed mild alveolar bone resorption with slight inflammation when the rats were fed Diet 2000 for six months. In the periodontal tissue, we found inflammatory cell infiltration, destruction of the periodontal ligament, and lacunae in the alveolar bone due to resorption. The phagocytic activity of M phi treated with Bone-sups was suppressed before the periodontal tissue, which is inflammatory condition such as alveolar bone resorption. Furthermore the phagocytic activity of resident M phi taken from rats on the Diet 2000 was suppressed. After one month of the Diet 2000, the activity of acid phosphatase (AcP), a lysosomal enzyme of M phi, was suppressed, but by six months it was enhanced. The activity of beta-N-acetyl-D-glucosaminidase (NAG), another lysosomal enzyme of M phi, was suppressed over the total period of Diet 2000 before the periodontal tissue was destroyed. These findings suggest that the capacity for defense against infection by M phi is suppressed when periodontitis is initiated by Diet 2000 feeding and that M phi activities are influenced by some factors elaborated by cells in the alveolar bone.

Alveolar Bone Loss↗
PubMed1990

[Surgical anatomy of the so-called dangerous frontal sinus (Boenninghaus)].

Surgically dangerous type of frontal sinus was first reported by Boenninghaus in 1923. The present study concerns with the types and incidence of the dangerous frontal sinus as investigated by axial scans of HRCT. A total of 286 adult and 33 infant cases was included. The anterior end of the olfactory groove was first classified into three types, i.e., normal type, obliterated type (obliterated by cancellous bone) and dangerous type (with Recessus cristae galli and Torus olfactorius). In the adult, the incidences of these types are, 67.2, 18.5 and 14.3%. In the infant, incidences are 42.4, 51.5 and 6.1%. In the adult, the incidences do not differ in sex and sides. The dangerous type was classified into moderate and severe according to the depth of Recessus cristae galli, those with 1.5-2.9 mm depth are moderate and those over 3.0 mm are severe. The moderate dangerous type was seen in 30 sides and severe in 46 sides. In addition to the depth of Recessus cristae galli, distances from Torus olfactorius to the anterior sinus wall and the frontal skin surface were also included. These distances tend to be larger in male.

Adolescent↗
PubMed1990

Retrovirus-like particles in human thymomas.

The pathogenesis of thymoma is unclear. In this study retrovirus-like particles in human thymomas were detected by electron microscopy. Forty-two thymomas; 25 without complications and 17 associated with autoimmune disorders such as myasthenia gravis (13), systemic lupus erythematosus (1), polymyositis (1), Sjögren's syndrome (1), and pure red cell anemia (1), were examined. Thymic tissues from 9 infants suffering from congenital heart diseases and 7 hyperplastic thymuses obtained from myasthenic patients served as controls. The retrovirus-like particles were observed in 37.0% of thymomas without complications; 50.0% of thymomas associated with myasthenia gravis and other autoimmune disorders; 62.5% of thymuses associated with myasthenia gravis; and 33.3% of thymuses from infants with heart disease. The envelopes, including the central cores of the retrovirus-like particles, had diameters ranging from 70 to 460 nm, depending on the source of the specimen. The retrovirus-like particles were located in the cytoplasm, vacuoles, vesicles and lumens of the endoplasmic reticula of epithelial and/or plasma cells. Some retrovirus-like particles were seen budding from plasma membranes. These observations suggest that the retrovirus-like particles in thymomas might be an activated form of retrovirus originating in normal thymic tissue.

Heart Defects, Congenital↗