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Biomedical subjects

H Ichikawa

Publications and source records attributed to H Ichikawa.

At least 19 recordsLinked to original sources
PubMed1992

Calretinin-immunoreactivity in the oro-facial and pharyngeal regions of the rat.

Calretinin-immunoreactivity (CR-ir) was examined in the rat oro-facial and pharyngeal tissues using an immunofluorescence method. CR-ir was distributed in the entire size range of trigeminal ganglion neurons. CR-ir was also observed in nerve fibers surrounding neuronal cell bodies in autonomic ganglia, and in nerve endings in the lip, tongue, incisal papilla, soft palate, pharynx and epiglottis. CR-immunoreactive nerve endings were all in close proximity to the epithelium, and classified into 2 types; simple (free nerve ending) and taste-bud-related types. In the salivary gland, positive nerve fibers were seen around large excretory ducts. The present study indicates that viscerosensory (probably including gustatory) nerve fibers innervating the oral and pharyngeal tissues contain CR, while somotosensory nerve fibers innervating the facial skin are devoid of CR.

Animals↗
PubMed1992

Sporulation regulatory protein GerE from Bacillus subtilis binds to and can activate or repress transcription from promoters for mother-cell-specific genes.

The mother-cell line of gene expression during sporulation in Bacillus subtilis is a hierarchical cascade consisting of at least four temporally controlled gene sets, the first three of which each contain a regulatory gene for the next gene set in the pathway. gerE, a member of the penultimate gene set, is a regulatory gene whose products is required for the transcriptional activation of genes (coat protein genes cotB and cotC) in the last gene set. The gerE product also influences the expression of other members of the penultimate gene set (coat protein genes cotA and cotD appear to be repressed and activated, respectively). We now report that the purified product of gerE (GerE) is a DNA-binding protein that adheres to the promoters for cotB and cotC. We also show that GerE stimulates cotB and cotC transcription in vitro by RNA polymerase containing the mother-cell sigma factor sigma K. These findings support the view that GerE is a positively acting, regulatory protein whose appearance at a late stage of development directly activates the transcription of genes in the last known temporal class of mother-cell-expressed genes. In addition, GerE stimulates cotD transcription and inhibits cotA transcription in vitro by sigma K RNA polymerase, as expected from in vivo studies, and, unexpectedly, profoundly inhibits in vitro transcription of the gene (sigK) that encodes sigma K. The effects of GerE on cotD and sigK transcription are just the opposite of the effects exerted by the earlier-appearing, mother-cell regulatory protein spoIIID, suggesting that the ordered appearance of first SpoIIID, then GerE, ensures proper flow of the regulatory cascade controlling gene expression in the mother cell.

Bacillus subtilis↗
PubMed1992

Cytochrome oxidase activity in vagal and glossopharyngeal visceral sensory neurons of the rat: effect of peripheral axotomy.

Cytochrome oxidase (CO) activity, an endogenous metabolic marker, was examined in visceral sensory neurons of the rat nodose and petrosal ganglia by using enzyme histochemistry. In the normal nodose and petrosal ganglia, nerve cells showed various degrees of staining intensity. The population of darkly stained neurons in the nodose ganglion was higher than in the petrosal ganglion. Axotomy of the peripheral axons of these bipolar sensory neurons was used to study potential changes in ganglionic cellular metabolism associated with loss of afferent inputs and/or injury. Peripheral axotomy had a significant effect on CO activity in the nodose ganglion. By 3 days after axotomy, darkly stained neurons decreased in number and lightly stained neurons, which were not observed in the normal ganglion, appeared in the nodose ganglion. At 7 days after axotomy, the average population of these lightly stained neurons increased to 29% in the nodose ganglion. Subsequently, the population decreased so that at 14 days and 21 days, 19% and 7% respectively of neurons were stained lightly. Even at 28 days after axotomy, the lightly stained neurons were still observed. In the petrosal ganglion, no remarkable change was observed at any stage after axotomy. These results suggest that metabolic activity decreases in some nodose neurons after peripheral nerve section.

Animals↗
PubMed1992

Long-distance restriction mapping of the proximal long arm of human chromosome 21 with Not I linking clones.

Human chromosome 21 is the smallest of the 22 autosomes and 2 sex chromosomes. Hybridization of the human repetitive sequence Alu to pulsed-field gel-fractionated Not I-digested genomic DNA from a human-mouse hybrid cell line containing chromosome 21 as the sole human component identified chromosome 21 Not I restriction fragments. A Not I restriction map of regions of the chromosome was constructed, by identifying neighboring Alu bands with Not I linking clones. This approach simplifies the task of physical mapping and avoids ambiguities in Not I fragment assignments that arise from gel-to-gel mobility variations. A contiguous map was constructed with six Not I linking clones that covers at least the proximal one-third of the long arm of chromosome 21 and spans 20 megabases. A more detailed restriction map revealed 11 likely CpG islands in this region and localized 11 additional DNA markers.

Chromosomes, Human, Pair 21↗
PubMed1992

Changes of cytochemical properties in the Golgi apparatus during in vivo differentiation of the ameloblast in developing rat molar tooth germs.

The cytochemical changes of the Golgi stacks occurring concomitantly with cell differentiation were examined in ameloblasts of developing rat molar tooth germs using osmium impregnation and cytochemistry with nicotinamide adenine dinucleotide phosphatase (NADPase), thiamine pyrophosphatase (TPPase), and acid phosphatase (Acpase). NADPase, TPPase, and Acpase activities were already present in the Golgi stacks of the inner enamel epithelial cells, the undifferentiated form of the ameloblast: NADPase activity existed in the medial Golgi cisternae, TPPase activity in the trans Golgi cisternae, and Acpase activity in almost all cisternae and strongly in the trans-most cisterna of the Golgi stack. At this stage, however, osmium deposits after impregnation were not observed in the cisterna of Golgi stacks but were present in some small vesicles. These vesicles were located throughout the cytoplasm. Osmiophilic cisternae in the Golgi stacks were apparent for the first time at the stage when the Golgi apparatus developed and migrated to the region distal to the nucleus with the progression of cell differentiation. These findings indicate that the cis subcompartment of the Golgi apparatus was incomplete in the inner enamel epithelial cells with regard to appearance of its cytochemical property, as compared with the medial and trans subcompartments. It is suggested that the cis compartment of the Golgi stack may be completed only in the last stage of the compartmentalized Golgi organization during differentiation of the ameloblast.

Acid Phosphatase↗
PubMed1992

Role of leukotrienes in gastric mucosal injury induced by ischemia-reperfusion in rats.

This study was designed to clarify the role of leukotrienes (LTs) in gastric injury induced by ischemia-reperfusion in rats. Gastric lesions were produced by clamping of the celiac artery and by reoxygenation following clamping. Administration of AA-861, a lipoxygenase inhibitor, significantly inhibited the increase in the total area of the gastric erosions and the increase in thiobarbituric acid-reactive substances in the gastric mucosa. Administration of YM-638, a peptide LT antagonist, showed protective effects similar to AA-861. These results suggest that the protective effects of AA-861 and YM-638 against ischemia-reperfusion-induced gastric injury were due to their antioxidative action.

Animals↗
PubMed1992

Acute spinal epidural abscess and spinal leptomeningitis: report of 2 cases with comparative neuroradiological and autopsy study.

A 21-year-old male developed back pain, fever, and rapidly progressive quadriparesis. Lumbar tap yielded frank pus which was confirmed on magnetic resonance imaging (MRI) to be located mainly in the cervical epidural space. Conservative antibiotic remedy was partially effective for restoration of the neurological deficits. A 82-year-old female noticed low-back pain which was rapidly accompanied with clouding of consciousness, paraplegia, and sphincter disturbances. Lumbar puncture revealed thick pus which was best depicted on MRI in the thoracolumbar subarachnoid space. At autopsy, spinal subarachnoid abscess or leptomeningitis was confirmed, and a spinal infarction previously unrecognized on MRI was found. Usefulness and shortcomings of MRI in the diagnosis of paraspinal infections are discussed.

Abscess↗
PubMed1992

Distribution of calcitonin gene-related peptide and substance P-immunoreactive nerve fibers and their correlation in the periodontal ligament of the mouse incisor.

The distribution of calcitonin gene-related peptide (CGRP)- and substance P (SP)-immunoreactive (IR) nerve fibers and their correlation in the periodontal ligament of mouse incisors were examined by indirect immunofluorescence. Both CGRP-IR and SP-IR thin nerve fibers were abundant in the apical and middle third of the periodontal ligament. In the lingual portion of the incisal periodontal ligament, these nerve fibers were localized in the alveolar half of the periodontal ligament and were observed as free nerve endings. No CGRP-IR and SP-IR specialized nerve endings, such as Ruffini-like corpuscles, were observed. In the labial periodontal ligament, CGRP-IR and SP-IR nerve fibers ran along the incisal axis. The distribution of CGRP-IR nerve fibers was very similar to that of SP-IR nerve fibers.

Animals↗
PubMed1992

Computer simulation of agglomeration in the Wurster process.

A simplified model for computer simulation of agglomeration in the Wurster coating process was constructed using droplet size distribution and the relation between the size of agglomerates and the number of primary particles composing them experimentally determined. Computer simulations were applied to the cases where a 2.5% aqueous solution of hydroxypropyl cellulose (containing sodium carboxymethyl cellulose of 10% on a dry basis) was sprayed on four kinds of sharply fractionized lactose powders between 32 and 75 microns. With cores larger than 53 microns, the agitation exerted on particles strongly suppressed the growth of agglomerates, but the fraction of produced agglomerates reached about 50%. The smallest droplet size that was contributable to agglomeration (critical droplet size) was estimated to be 37.1-49.0 microns, increasing with core size, and the weight fraction of droplets larger than this critical size was only 0.5-2.7%, decreasing with increase in core size. The production of even such a minor amount of coarse droplets could be responsible for significant agglomeration.

Chemistry, Pharmaceutical↗
PubMed1992

Relationships between biological potency and electronic states of polychlorinated dibenzofurans and polychlorinated biphenyls.

It was found that the differences between the frontier molecular orbital energies (epsilon homo - epsilon lumo = delta epsilon) in polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) have a correlationship with the magnitude of the biological activity which is influenced by both the number and position of chlorine atom substituents on PCDFs and PCBs skeletons. Moreover, it was found that the delta epsilon's values of PCBs are classified into two types which coincide with the well-known classification of PCBs to types of 3-methylcholanthrene and phenobarbital according to their biological activities. The relationship between delta epsilon and biological activity in these xenobiotics suggests that the congeners having small delta epsilon values as 2,3,4,7,8-pentaCDF, 2,3,4,6,7-pentaCDF, 3,4,5,3',4'-pentaCB, and 3,4,5,3',4',5'-hexaCB form stable molecular complexes with an Ah-receptor, e.g. (2,3,4,7,8-PentaCDF-Ah-receptor), while the congeners having large delta epsilon values are strongly suggested to be unstable in a complex formation. Thus, this work presents an explanatory method to help understand the structure-activity relationship of the xenobiotics PCDFs and PCBs.

Animals↗
PubMed1992

[The effects of potassium concentration in reperfusion solution upon myocardial protection].

The effects of potassium in reperfusion solution (RS) and the influence of sodium on this effect were studied. Experimental time course was as followed: 20 min working perfusion, 3 min cardioplegic infusion with St. Thomas Cardioplegic Solution followed by global ischemia for 33 or 35 min at 37.5 degrees C, 15 min early Langendorff reperfusion with several different potassium concentration modified with Krebs Henseleit Bicarbonate Buffer (KHBB) containing 145 mM and 110 mM sodium and 5 min late reperfusion with KHBB, followed by 20 min working perfusion. Potassium in RS possessed bell shaped dose response nature with optimal concentration of 10 mM in the condition of 145 mM sodium but 6 m in the condition of 110 mM in terms of percent recovery of aortic flow. Although higher potassium reperfusion produced less Creatine Kinase leakage.

Animals↗
PubMed1992

Increase in c-fos-like immunoreactivity in the trigeminal nucleus complex after dental treatment.

An immunohistochemical study was made of the temporal changes in the expression of the c-fos oncogene protein in the spinal trigeminal nucleus complex (STNC) after three different types of dental injury. One hour after tooth extraction or pulp exposure, c-fos neurons appeared in the ipsilateral subnucleus caudalis, but there were very few c-fos neurons in the ipsilateral subnuclei oralis and interpolaris, and in the trigeminal main sensory nucleus and contralateral STNC. The great number of c-fos neurons was found 2-4 hours after injury, levels decreased by 8 hours after injury. Twenty-four hours after injury, the number of these neurons in subnucleus caudalis became very small. Shallow cavity preparation, however, did not induce an increase in the number of c-fos neurons at any selected postoperative time in STNC. These results indicate that c-fos neurons appear mainly in subnucleus caudalis very soon after severe dental injury.

Animals↗
PubMed1992

[The effects of sodium concentration in reperfusion solution upon myocardial protection].

The effects of several sodium concentrations in reperfusion solution (RS) were studied. Experimental time course was as follows: 20 min working perfusion, 3 min cardioplegic infusion with St. Thomas Cardioplegic Solution followed by global ischemia for 33 min at 37.5 degrees C, 15 min early Langendorff reperfusion with various sodium concentrations modified with Krebs Henseleit Bicarbonate Buffer (KHBB) and 5 min late reperfusion with KHBB, followed by 20 min working perfusion. Percent recoveries of aortic flow and Creatine Kinase leakage showed that 110 mM sodium of RS possessed optimal protective properties with bell shaped dose response characteristics.

Animals↗
PubMed1992

[The effects of osmolarity in reperfusion solution upon myocardial protection].

The effects of several different osmolarity in reperfusion solution were studied. Experimental time course was as follows: 20 min working perfusion, 3 min cardioplegic infusion with St. Thomas Cardioplegic Solution (STS) followed by global ischemia for 33 min at 37.5 degrees C, 15 min early Langendorff reperfusion with different osmolarity by adding sucrose and 5 min late reperfusion with Krebs Henseleit bicarbonate buffer, followed by 20 min working perfusion. Percent recoveries of aortic flow showed that 290 mOsm/L in reperfusion solution possessed optimal protective properties with bell shaped dose response characteristics.

Animals↗
PubMed1991

Calretinin-immunoreactivity in vagal and glossopharyngeal sensory neurons of the rat: distribution and coexistence with putative transmitter agents.

Immunoreactivity for the calcium binding protein, calretinin (calretinin-ir), was demonstrated in cell bodies of vagal and glossopharyngeal sensory ganglia (jugular, petrosal, and nodose ganglia) and in associated nerve fibers. In the jugular and petrosal ganglia, many calretinin-ir neurons were also immunoreactive for calcitonin gene-related peptide and substance P. In the nodose ganglion, most of the calretinin-ir neurons lacked these peptides. None of the calretinin-ir neurons in these ganglia were also immunoreactive for tyrosine hydroxylase.

Animals↗
PubMed1991

Molecular assignment of a translocation breakpoint in acute myeloid leukemia with t(8;21).

An 8;21 translocation is a common chromosome abnormality associated with acute myeloblastic leukemia with maturation (M2 of French-American-British (FAB) classification). We have isolated chromosome 21 Notl linking clones; pulsed field gel electrophoresis analysis with one clone (LL263) detected an altered fragment of Notl-digested leukemic cell DNA carrying t(8;21). The altered fragment was shown to be produced by the 8;21 translocation. The breakpoint in chromosome 21 was located about 13 kb to 100 kb proximal to the LL263 Notl site. Because the LL263 clone has a CpG island and is a short distance from the breakpoint, the clone itself may be considered as a candidate for part of the t(8;21) associated gene.

Acute Disease↗
PubMed1991

The effects of several pharmacologic agents upon postischemic recovery.

Using an isolated working rat heart model, the effects of DL-verapamil, ryanodine, gabexate mesilate (FOY), recombinant human superoxide dismutase (RH-SOD), and coenzyme Q10 upon myocardial protection were evaluated. Under conditions of normothermic ischemia, all these compounds, except RH-SOD, when added to the St. Thomas' cardioplegic solution at an optimal concentration, showed beneficial effects upon functional recovery and enzyme leakage. In contrast, the above compounds, except ryanodine and FOY, failed to improve the protective properties of the St. Thomas' cardioplegic solution under conditions of hypothermic ischemia. Our results indicate that calcium overload via the calcium channel and calcium-induced calcium release from sarcoplasmic reticulum (SR) may contribute to the onset of ischemic-reperfusion injury. However, under conditions of hypothermic ischemia, calcium-induced calcium release from SR plays a dominant role in calcium overload. Furthermore, intracellular calcium overload may activate proteases and result in the acceleration of myocardial injury.

Animals↗