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Biomedical subjects

K Ichimura

Publications and source records attributed to K Ichimura.

At least 163 records · Page 9Linked to original sources
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↗
PubMed1989

Dissociation and auto-oxidation of hemerythrin induced by SH-modification: a kinetic study.

Hemerythrin from Siphonosoma cumanense has a trimeric structure consisting of identical subunits, which have no cooperativity nor Bohr effect on oxygen-binding. The trimer was dissociated into its monomers by the modification of the SH group of its cysteines with p-chloromercuriphenylsulfonic acid (PCMPS), which was monitored by stopped-flow of both spectrophotomeric and small angle X-ray scattering methods. The results showed that the process involved sequential modification of the SH groups, dissociation into monomers, and auto-oxidation of ferrous iron in the active center. The modification of the SH groups with PCMPS followed second-order kinetics with a rate constant of 1.8 M-1.s-1. The dissociation and auto-oxidation followed first-order kinetics with rate constants of 4 X 10(-3) s-1 and 5 X 10(-4) s-1, respectively. The obtained rate of auto-oxidation was much faster than that in the native state. These findings lead to the conclusion that the trimeric state of S. cumanense hemerythrin is necessary to prevent auto-oxidation.

Animals↗
PubMed1989

Negative cooperativity of chicken ovotransferrin on Al(III)-binding.

Chicken ovotransferrin, an iron binding protein, has two metal binding sites (amino (N) and carboxy (C) terminal sites). It binds Cu(II), Al(III), Co(II), and other metals, as well as Fe(III). In this study, the selectivity and cooperativity of the N and C sites on Al(III), Co(II), and Tb(III) binding were investigated. Metals were classified into two groups according to their site preference. Co(II) and Al(III) bound to the N site more preferably than to the C site, whereas Tb(III) bound to the C site more preferably. On Fe(III) binding, the binding constant of Fe(III) becomes larger when the other site is already occupied. Thus, positive cooperativity is seen. In the present study, the binding cooperativities of Co(II), Tb(III), and Al(III) as to the N and C sites were investigated. On Co(II) and Tb(III) binding, no cooperativity was observed, as in the case of Cu(II) [Yamamura, T. et al. (1985) in Proteins of Iron Storage and Transport (Spik, G., Montreuil, J., Crichton, R.R., & Mazurier, J., eds.) pp. 53-56, Elsevier Science Publ. B.V., Amsterdam]. In contrast, negative cooperativity was observed on Al(III) binding. Based on a model proposed by Yamamura et al. [Yamamura, T. et al. (1985) ibid.], the ratio of the binding constants, KC/KN, and the stacking coefficient, Kst, were estimated. KC/KN is 2.2 +/- 0.4 for the Tb(III) ion, 0.5 +/- 0.1 for the Co(II) ion, and 0.12 +/- 0.02 for the Al(III) ion. Kst (= 1 in a non-cooperative case) is 0.98 +/- 0.02 for the Tb(III) ion, 1.03 +/- 0.02 for the Co(II) ion, and 0.55 +/- 0.22 for the Al(III) ion.

Aluminum↗
PubMed1989

[Effects of periodontopathic bacterial components on phagocytic activity of rat peritoneal macrophages. Examination using ELISA].

This study examined the phagocytic activity of rat peritoneal resident macrophages to determine the movement of macrophages in local inflammation in periodontal disease. We studied phagocytic activity by enzymelinked immunosorbent assay (ELISA) and used the peroxidase-anti-peroxidase soluble complex (PAP; soluble immune complex) as a marker in. We also determined the basic conditions of this examination and studied the effects of bacterial components and the supernatants of sonicated periodontopathic bacterias. We obtained the number of applied macrophages, the concentration of PAP to use and the incubation time. The phagocytic activity of macrophages was enhanced significantly by the bacterial components lipopolysaccharide (LPS) and muramyldipeptide (MDP). Phagocytic activity was also enhanced by the addition of the supernatant of sonicated Bacteroides gingivalis at 40 micrograms/ml (concentration of protein) and significantly suppressed at 320 micrograms/ml. Moreover, activity was significantly enhanced by the supernatant of sonicated Capnocytophaga suputigena at 40 micrograms/ml and 160 micrograms/ml, and suppressed by the supernatant of Fusobacterium nucleatum at a low concentration of protein (5 micrograms/ml). These results suggested that LPS of gram-negative bacteria's endotoxicity and MDP on pivotal structure of peptidoglycans, which are bacterial cell surface components, exerted an effect on phagocytic activity. It was further indicated that the phagocytic activity of macrophages varied with the effects of each periodontopathic bacteria.

Animals↗
PubMed1989

[The role of high-resolution CT in evaluating disease of the posterior tympanum].

The posterior tympanum consists of several irregular eminences, ridges, and sinuses. These sinuses do not communicate with the mastoid air cell system, and cholesteatoma and/or granulation tissue prefer to fill them. This area cannot be visualized with ease by the usual surgical approach, and is thus quite important for surgeons. Recent developments in high-resolution computed tomography (HRCT) allow more than ever precise identification of subtle changes in the posterior tympanum. Axial HRCT sections provide essential information for the preoperative evaluation of the posterior tympanum. The performance of surgeons has been promoted both in evaluation and treatment planning of patient with suspected posterior tympanic lesions. HRCT findings were compared with the operative findings in 52 patients (54 ears) who had the operation for chronic otitis media. Important findings by HRCT diagnosis of posterior tympanum are as follows: (1) Bone destruction in the posterosuperior part of the tympanic anulus and in the lateral wall of the facial sinus are the important findings for the diagnosis of invasion of cholesteatoma in the posterior tympanum. (2) Similarly important finding is the bone destruction of the pyramidal eminence. This was found in 6 of 9 cases with cholesteatomas extending into the sinus tympani. (3) The soft tissue density in the posterior tympanum does not necessarily indicate pathological processes. Effusion in the posterior tympanum is imaged as soft tissue density, and can not be differentiated from cholesteatoma or granulation by present HRCT.

Adolescent↗
PubMed1989

[Superstructure of stapes: an analysis by high-resolution computed tomography].

High-resolution Computed Tomography (HRCT) of the temporal bone has now become a routine test for the diagnosis of various temporal bone lesions. Correct assessment of such minute structures as ossicles, especially stapes, is important in the pre-operative HRCT evaluation. On the other hand, analysis for the reliability of HRCT findings has not been done, including the superstructure of the stapes. A retrospectively study was done in order to assess the availability of HRCT findings in axial overlapping scans in 226 ears, with respect to the superstructures of stapes. The study was concerned with the analysis of HRCTs of 148 normal ears, 71 ears of chronic otitis media and 7 ears of ossicular abnormalities. HRCT findings were compared to those of surgeries in pathological cases. The present study revealed that the superstructures of stapes are noted in 70% when the stapes surrounded by air. The major limitations in the proper analysis of stapes by HRCT are partial volume averaging and effects of soft tissue silhouetting, this is especially so when the stapes is surrounded by soft tissue density.

Chronic Disease↗
PubMed1989

Auto-oxidation of Lingula unguis and Siphonosoma cumanense hemerythrins induced by some perturbants.

Auto-oxidation of human adult hemoglobin and Siphonosoma cumanense and Lingula unguis hemerythrins were investigated in the presence and absence of perturbants. In the presence of urea, there were no drastic increases in auto-oxidation rates for the three proteins. In contrast, thiocyanate and laurate enhanced the auto-oxidation rates remarkably. In the presence of thiol reagents such as PCMB and NEM, auto-oxidation rates were enhanced with dissociation into subunit, but not enhanced so much with SH-modification only. Thus oligomerization is probably necessary to protect auto-oxidation.

Animals↗
PubMed1988

Postjunctional alpha 2-adrenoceptors in blood vessels of human nasal mucosa.

Human nasal mucosa has various types of blood vessels and is a good tissue for demonstrating receptors for many vasoactive substances, including alpha-adrenoceptors. In contrast to the large contractile response induced by alpha 1-agonists, our studies have shown that alpha 2-agonists produce a small maximal contraction. This alpha 2-induced response was easily blocked by alpha 1-antagonists, indicating that it is evoked, at least partially, by the stimulation of alpha 1-adrenoceptors. Noradrenaline (NA)-induced contractions could not be abolished by either alpha 1- or alpha 2-antagonists alone, but were almost completely blocked by the combination of both antagonists. This suggests the presence of postjunctional alpha 2-adrenoceptors. The low-maximal responsiveness to alpha 2-agonists and calcium independency of NA-induced contractions were distinct from our former results obtained on canine nasal specimens.

Adrenergic alpha-Agonists↗