Biomedical subjects

K Kitamura

Publications and source records attributed to K Kitamura.

At least 217 records · Page 12Linked to original sources

PubMed1999

Cyclic AMP-dependent synthesis and release of adrenomedullin and proadrenomedullin N-terminal 20 peptide in cultured bovine adrenal chromaffin cells.

Adrenomedullin and proadrenomedullin N-terminal 20 peptide are peptides with multiple physiological functions and are most abundant in adrenal medulla. We studied whether the cAMP-dependent pathway is involved in the regulation of synthesis and release of adrenomedullin and proadrenomedullin N-terminal 20 peptide in cultured bovine adrenal chromaffin cells. Exposure of the cells to dibutyryl cAMP (dbcAMP) increased a progressive accumulation of immunoreactive-adrenomedullin and immunoreactive-proadrenomedullin N-terminal 20 peptide in the extracellular medium, while reciprocally decreasing their cellular content in a time-dependent manner. The decrease of levels of both peptides in the cells was much greater in extent than the increase of the peptides in the medium. H89, an inhibitor of cAMP-dependent protein kinase attenuated these changes, induced by dbcAMP. The resulting changes by dbcAMP and H89 were similar to those of chromogranin B, a marker peptide of chromaffin granule. Northern blot analysis showed that the mRNA encoding these peptides, detected as a band of 1.6 kb, was decreased by the treatment with dbcAMP. The effect of dbcAMP on mRNA was attenuated by H89, and was reversible as the decreased mRNA level caused by dbcAMP could be returned to control levels by culturing cells after removal of dbcAMP. These results suggest that the cAMP-dependent protein kinase pathway stimulates the release of adrenomedullin and proadrenomedullin N-terminal 20 peptide, whereas it lowers synthesis of these peptides via the reduction of their transcript level.

Adrenal Medulla↗

PubMed1999

Cell fate analysis of teloblasts in the Tubifex embryo by intracellular injection of HRP.

As in other clitellate annelids, embryonic development in the oligochaete Tubifex is characterized by the generation of five bilateral pairs of teloblasts (designated M, N, O, P and Q), which serve as embryonic stem cells to produce germ bands on either side of the embryo. A large part of the tissues comprising body segments has been assigned to the progenies of the teloblasts; however, the developmental fate of each teloblast has been inferred only from its initial position in the embryo. In the present study, the fate of the progenies of each teloblast was followed by means of intracellular injection of a tracer enzyme, horseradish peroxidase. Cell fate maps for teloblasts in the Tubifex embryo were constructed. M teloblasts gave rise to nearly all of the mesodermal tissues, which included circular and longitudinal muscles, coelomic walls, nephridia (in segments VII and VIII) and primordial germ cells (in segments X and XI). Although few in number, M teloblasts also contributed cells to the ventral ganglion. Similarly, each of the ectoteloblasts, N, O, P and Q, made a topographically characteristic contribution to the ectodermal tissues such as the nervous system (i.e. ganglionic cells and peripheral neurones) and epidermis, all of which exhibited a segmentally repeated distribution pattern. The P and Q teloblasts uniquely gave rise to additional ectodermal tissues, namely ventral and dorsal setal sacs, respectively. Furthermore, O teloblasts made a contribution to the nephridiopores in segments VII and VIII as well. These results confirm the previously held view that ectoteloblasts and mesoteloblasts are the main source of ectodermal and mesodermal segmental tissues, respectively, but also suggest that all of the teloblasts produce more types of tissue than has previously been thought.

Animals↗

PubMed1999

Evaluation of inner ear histology and auditory brainstem response in Wriggle Mouse Sagami.

Wriggle Mouse Sagami (WMS) is a spontaneous mutant strain with neuroepithelial defects. These animals are characterized by abnormal movements linked to an autosomal recessive gene. To determine the association between inner ear histology and hearing ability, we assayed these characteristics in mice homozygous and heterozygous for the mutation, as well as in wild-type animals. In homozygotes, the cochlea and saccule degenerated 3 months after birth. Beginning at 3 months of age, and progressing in an age-dependent manner, the organ of Corti disappeared and the number of spiral ganglion cells decreased, starting at the basal turn and moving toward the apical turn. The sensory epithelium became atrophic in the saccule. Three-month-old heterozygotes demonstrated degeneration in the cochlea, not in the saccule. No obvious auditory brainstem evoked response (ABR) was observed at any frequency in homozygotes aged 1 month and older. In contrast, the heterozygotes retained some hearing acuity until the age of 1 month, after which they became deaf. These findings suggest that WMS mice may provide a good model that will be useful in identifying deafness genes in humans.

Animals↗

PubMed1999

Clinical features of paroxysmal positional vertigo presenting combined lesions.

Benign paroxysmal positional vertigo (BPPV) is one of the common vestibular disorders. Canalolithiasis is thought to be a likely lesion. A canalith repositioning procedure (CRP by Epley) generally yields good resolution of vertigo and nystagmus. The authors confirmed the efficacy of this procedure on typical BPPV of the posterior semicircular canal type. We designed a new procedure for BPPV of the lateral canal type, which also yielded satisfactory results. BPPV sometimes presents a nystagmus pattern, which suggests multiple lesions. We have seen eight cases of BPPV showing nystagmus that combines both the posterior and the lateral canal types. Combined CRP was performed on these cases, which again gave good clinical results. Other BPPV cases were associated with central lesions. We must be aware that BPPV may involve multiple canals and may be associated with central lesions.

Aged↗

PubMed1999

Isoflurane inhibits neuronal Ca2+ channels through enhancement of current inactivation.

To help clarify the mechanisms by which volatile anaesthetics act on neuronal Ca2+ channel currents (IBa), the effects of isoflurane were studied on IBa in rat dorsal root ganglion (DRG) cells. Voltage-dependent IBa were pharmacologically subdivided into L-, N- and P/Q-types, and toxin-resistant IBa. At clinically relevant concentrations, isoflurane inhibited the L-, N- and P/Q-types, but not toxin-resistant IBa. The IC50 values for the L-, N- and P/Q-types were 0.7%, 1.3% and 3.0%, respectively (concentrations equivalent to 0.35, 0.68 and 1.46 mmol litre-1 in the aqueous phase). Isoflurane also produced initial transient augmentation of the N-type IBa. Isoflurane shifted the mid-point of the steady-state inactivation curve for the L-, N- and P/Q-type IBa towards negative potentials, and prolonged the time constant of current reactivation. We conclude that isoflurane inhibited L-, N- and P/Q-type IBa in rat DRG neurones by enhancing current inactivation and prolonging recovery time after inactivation. Transient augmentation of the N-type IBa may also form part of the overall actions of isoflurane in DRG neurones.

Anesthetics, Inhalation↗

PubMed1999

Resistance to gap repair of the transposon Tam3 in Antirrhinum majus: a role of the end regions.

The extremely homogeneous organization of the transposon family Tam3 in Antirrhinum majus is in sharp contrast to the heterogeneity of the copies constituting many other transposon families. To address the issue of the Tam3 structural uniformity, we examined two possibilities: (1) recent invasion of Tam3 and (2) failure of gap repair, which is involved in conversion from autonomous forms to defective forms. The phylogenetic analysis of 17 Tam3 copies suggested that the invasion of Tam3 into the Antirrhinum genome occurred at least 5 mya, which is sufficiently long ago to have produced many aberrant copies by gap repair. Thus, we investigated gap repair events at the nivea(recurrens:Tam3) (niv(rec)::Tam3) allele, where Tam3 is actively excised. We show here that the gap repair of de novo somatic Tam3 excision was arrested immediately after initiation of the process. All of the identified gap repair products were short stretches, no longer than 150 bp from the ends. The Tam3 ends have hairpin structures with low free energies. We observed that the gap repair halted within the hairpin structure regions. Such small gap repair products appear to be distributed in the Antirrhinum genome, but are unlikely to be active. Our data strongly suggest that the structural homogeneity of Tam3 was caused by immunity to gap repair at the hairpins in both of the end regions. The frequency of extensive gap repair of de novo excision products in eukaryotic transposons was found to be correlated with the free energies of the secondary structures in the end regions. This fact suggests that the fates of transposon families might depend on the structures of their ends.

Alleles↗

PubMed1999

Number and anatomical extent of lymph node metastases in gastric cancer: analysis using intra-lymph node injection of activated carbon particles (CH40).

BACKGROUND: The long-term survival of 200 patients with gastric cancer who underwent radical gastrectomy was analyzed with respect to the number and anatomical extent of lymph node metastasis. All of the patients received intra-lymph node injection of fine activated carbon particle solution (CH40) during surgery. METHODS: The average number of resected lymph nodes increased in line with the anatomical level of lymph node dissection; 32.5 per patient in D1, 42.3 in D2, 3 and 66.3 in D4. The percentage of blackened lymph nodes without metastasis (42.4%) was slightly higher than that of lymph nodes containing metastasis (37.2%), but the difference was not statistically significant. Of the 200 patients, 61 (30.5%) had microscopic evidence of metastatic lymph node involvement. Twenty-two patients had between one and three metastatic lymph nodes, 19 had between four and nine and 20 patients had more than nine. The 5-year survival rate was 93.1% in patients without lymph node metastasis, 71.9% in patients with 1-8 metastatic nodes, 36.1% in patients with 4-9 nodes and 19.2% in patients with > 9 nodes. RESULTS: The 5-year survival rate according to the anatomical extent of metastatic lymph nodes was 93.1% in n0, 63.1% in n1, 37.9% in n2, 27.8% in n3 and 0% in n4. The number of metastatic lymph nodes and also their anatomical extent were identified as independent prognostic factors for survival by multivariate analysis. CONCLUSION: The number and anatomical extent of metastatic lymph nodes have similar impacts on prognosis in gastric cancer.

Adult↗

PubMed1999

Pseudolymphomatous folliculitis: a clinicopathologic study of 15 cases of cutaneous pseudolymphoma with follicular invasion.

We report the clinical, histopathologic, and immunohistologic features of 15 cases of pseudolymphomatous folliculitis (PLF). The patients comprised seven males and eight females (mean age, 38.6 years; age range, 2-67 years). All patients had dome-shaped or flat-elevated nodules suggestive of cutaneous lymphoid hyperplasias (CLHs). The lesions were solitary in all 15 cases, except in one case with duplex lesions. All lesions were located on the face and measured less than 1.5 cm. In 14 cases with one lesion each, five lesions showed rapid regression after incisional biopsy, whereas the remaining nine underwent excisional biopsy. In the case with duplex lesions, one regressed spontaneously after excisional biopsy of the other. Histopathologically, all PLFs showed dense lymphocytic infiltrates from the dermis to the subcutis simulating cutaneous lymphomas. The walls of hair follicles in all cases were enlarged and irregularly deformed with their epithelium blurred by lymphocytic infiltrates; we called this change "activation" of hair follicles. In nine cases, many atypical lymphocytes were intermingled; three of these cases had been misdiagnosed as cutaneous T-cell lymphoma at other institutions. Immunohistologically, 10 and 5 cases showed predominantly B cells and predominantly T cells, respectively. Remarkably, all lesions showed increased numbers of perifollicular histiocytes expressing anti-S-100 protein and CD1a, and seven lesions showed histiocytes in aggregates. We conclude that PLF is a subset of CLH with characteristic clinical and pathologic features showing perifollicular clustering of T-cell-associated dendritic cells with activation of pilosebaceous units. PLF is an entity to be differentiated from malignant lymphomas and other cutaneous pseudolymphomas.

Adolescent↗

PubMed1999

A case of generalized morphea with a high titer of anti-Borrelia burgdorferi antibodies.

A 69-year-old male had noticed pruritus on the back for the previous 3-4 years and cutaneous sclerosis with swelling of the dorsum of the neck had developed in the last one and a half years. However, he had never complained of Raynaud's phenomenon of the fingers, dry mouth, or dry eyes. At this first visit to our hospital, he complained of erythematous cutaneous sclerosis with swelling of the dorsum of the neck. Histopathological findings biopsied from the neck showed epidermal hyperplasia with elongation of rete ridges and homogeneous and fibromatous changes of the dermis with dense perivascular cell infiltration consisting of mononuclear cells or lymphocytes with several nests of incontinentia pigmenti. However, there were no sclerotic changes in blood vessels in the upper dermis biopsied from the forearm skin, although slightly homogeneous and fibromatous changes of the dermis were seen. In the clinical course, the cutaneous sclerotic change enlarged to extend to the bottom of the cheek, forearm, and lower legs. These clinical features and histopathological findings led to the diagnosis of generalized morphea. Hematologic examination showed positive anti-Borrelia burgdorferi IgM antibodies, although there were no positive anti-Borrelia burgdorferi IgG antibodies. These results revealed that there can be a close association of localized scleroderma with Borrelia burgdorferi and that generalized morphea may also represent a Borrelia infection.

Aged↗

PubMed1999

Endothelin-B receptors activate Galpha13.

Endothelin (ET) receptors activate heterotrimeric G proteins that are members of the Gi, Gq, and Gs families but may also activate members of other families such as Galpha12/13. Galpha13 has multiple complex cellular effects that are similar to those of ET. We studied the ability of ET receptors to activate Galpha13 using an assay for G protein alpha-chain activation that is based on the fact that an activated (GTP-bound) alpha-chain is resistant to trypsinization compared with an inactive (GDP-bound) alpha-chain. Nonhydrolyzable guanine nucleotides and AlMgF protected Galpha13 from degradation by trypsin. In membranes from human embryonic kidney 293 cells that coexpress ETB receptors and alpha13, ET-3 and 5'-guanylylimidodiphosphate [Gpp(NH)p] increased the protection of alpha13 compared with Gpp(NH)p alone. The specificity of ETB receptor-alpha13 coupling was documented by showing that beta2 receptors and isoproterenol or ETA receptors and ET-1 did not activate alpha13 and that a specific antagonist for ETB receptors blocked ET-3-dependent activation of alpha13.

Cell Line↗

PubMed1999

Marked increase of guanylin secretion in response to salt loading in the rat small intestine.

Guanylin and uroguanylin are intestinal peptides that stimulate guanylate cyclase C and cause chloride secretion. These peptides show topological instability due to two disulfide bonds. The disulfide bonds were reduced and S-carboxymethylated to cleave the bonds and obtain stable and sole derivatives. We established a new and reliable RIA system for the stable derivatives from both peptides. With the use of this system, the response of the peptides to salt loading of the rat small intestine was evaluated. The lumen of the small intestines of Sprague-Dawley rats was perfused in vivo with Krebs-Ringer solution containing different concentrations of salt or mannitol. Mature guanylin, proguanylin, and mature uroguanylin were found in the perfusate in the basal state. The highest salt loading (200 mM NaCl for 20 min) increased the guanylin secretion about threefold (1.9 +/- 0.2 vs. 5.4 +/- 0.5 pmol/min), with the effect lasting for 60 min. The uroguanylin secretion was less affected. Hyperosmolar mannitol also caused a significant but smaller increase of guanylin secretion. Increased guanylin could lead to increased salt and water secretion of the intestine; thus members of the guanylin family have potential roles in the regulation of water and salt metabolism in the small intestine.

Amino Acid Sequence↗

PubMed1999

Choledochal cyst associated with polycystic kidney disease: report of a case.

We report a very rare case of type I choledochal cyst associated with a polycystic kidney disease. A 48-year-old female had been dependent on hemodialysis for chronic renal failure due to polycystic kidney disease and was incidentally diagnosed to have a dilated common bile duct by an ultrasonography. An endoscopic retrograde cholangiopancreatography showed a spindle-shaped, dilated common bile duct (type I choledochal cyst) without visualization of the pancreatic duct. She underwent a resection of the choledochal cyst. Intraoperative cholangiography showed no reflux of contrast medium into the pancreatic duct. Amylase level of the aspirated bile from the bile duct was not elevated. In the case of choledochal cyst combined with renal fibropolycystic disease, pancreaticobiliary maljunction may not contribute to the etiology of choledochal cyst. In such cases, management of choledochal cyst is still controversial and requires further discussion.

Cholangiopancreatography, Endoscopic Retrograde↗

PubMed1999

Corticosteroid-induced pancreatitis in patients with autoimmune bullous disease: case report and prospective study.

Corticosteroid pulse therapy using very high doses may produce corticosteroid-induced pancreatitis (CIP) that is unexpected during conventional oral corticosteroid therapy and may sometimes be fatal. Our goal was to evaluate the relation between pulse corticosteroid administration and pancreatitis. A case of CIP is reported, and a prospective study was performed. Corticosteroid pulse therapy followed by 30 mg prednisolone orally was utilized in 7 hospitalized patients with autoimmune bullous disease, and serum pancreatic enzymes were measured during therapy. The case report revealed reproducible pancreatitis in a dose-dependent manner after 2 corticosteroid regimens. In the prospective study, serum pancreatic enzyme levels increased significantly within several days after pulse therapy, then decreased with tapering of the dose of oral prednisolone. Laboratory pancreatic alterations appear to be induced within days after pulse corticosteroid administration in a dose-dependent manner: less than 25 mg of oral prednisolone may be below threshold to alter the pancreatic enzyme level.

Adrenal Cortex Hormones↗

PubMed1999

Bacterial interdigital scaly erythema (Kitamura): a possible new clinical entity.

Four patients with scaly erythema on their finger webs and sides of their fingers during summer are described. These patients were working in either butcher's shops or a sushi bar, where they handled raw meat, chicken or fish for many hours. The eruptions first appeared as scaly erythema, sometimes accompanied by small pustules, on the second, third and fourth finger webs, and later the erythema extended to the sides of the fingers and palms. Maceration and/or shallow erosion sometimes appeared on the finger webs. Symptoms were usually mild; the patients complained of slight itching, irritation or pain. Direct examination of specimens stained with Parker blue-black ink containing KOH revealed scales containing bacterial granules or filaments. Several species of bacteria were cultured including Corynebacterium sp. Fungus was not detected in either KOH specimens or in cultures. The lesions responded rapidly to topical or oral antibiotics; however, they recurred frequently during hot and humid weather. Hitherto a similar condition has not been described and is possibly a new clinical entity.

Adolescent↗

PubMed1999

Increased plasma proadrenomedullin N-terminal 20 peptide in patients with essential hypertension.

The novel hypotensive peptide, proadrenomedullin N-terminal 20 peptide (PAMP), is processed from the adrenomedullin precursor. Recently, we identified PAMP-12 [PAMP(9-20)] from the porcine adrenal medulla as a major endogenous and biologically active peptide. Using a new, sensitive radioimmunoassay which recognizes the C-terminal region of PAMP-20 [PAMP(1-20)], we investigated the role of PAMP in patients with essential hypertension who had normal renal function, and whether PAMP-12 is present in humans. The mean PAMP plasma concentration, like that of adrenomedullin, was significantly higher in hypertensive [1.51 fmol/mL, standard error of the mean (SEM) 0.09 fmol/mL] than normotensive participants (1.08 fmol/mL, SEM 0.05). The increase in plasma PAMP concentration in patients with organ damage accompanied by hypertension was significantly higher than that in patients without organ damage. The PAMP concentration had a significant positive correlation with mean blood pressure and adrenomedullin concentration. The immunoreactive PAMP in human tissue and plasma was characterized by reverse-phase high-performance liquid chromatography. PAMP-12, as well as PAMP-20, was abundant in the phaeochromocytoma tissue. These findings suggest that PAMP plays some pathophysiological role against the development of essential hypertension.

Adrenomedullin↗

PubMed1999

Centrally administered adrenomedullin increases plasma oxytocin level with induction of c-fos messenger ribonucleic acid in the paraventricular and supraoptic nuclei of the rat.

The effects of intracerebroventricular (i.c.v.) administration of adrenomedullin (AM) on plasma oxytocin (OXT), c-Fos protein (Fos), and c-fos messenger RNA (mRNA) in the paraventricular (PVN) and supraoptic nuclei (SON) of the rat were investigated using RIA for OXT, immunohistochemistry for Fos, and in situ hybridization histochemistry for c-Fos mRNA. Central administration of AM caused a significant increase in the plasma OXT level. Intracerebroventricular administration of AM caused a marked induction of Fos-like immunoreactivity (LI) in the PVN and in the dorsal parts of the SON. In the PVN and SON, OXT-LI cells predominantly exhibited nuclear Fos-LI in comparison with arginine vasopressin-LI cells. In situ hybridization histochemistry revealed that the induction of c-fos mRNA in the PVN and SON was increased in a dose-related manner 30 min after i.c.v. administration of AM. This induction was reduced by pretreatment with the AM receptor antagonist, human AM-(22-52)-NH2. These results suggest that central AM is responsible for activating the neurosecretory cells in the PVN and SON via selective AM receptors, and that AM stimulates the secretion of OXT by activating hypothalamic OXT-producing cells.

Adrenomedullin↗

PubMed1999

Mouse Pitx2 deficiency leads to anomalies of the ventral body wall, heart, extra- and periocular mesoderm and right pulmonary isomerism.

Pitx2, a bicoid-related homeobox gene, is involved in Rieger's syndrome and the left-right (L-R) asymmetrical pattern formation in body plan. In order to define the genomic structure and roles of Pitx2, we analyzed the genomic structure and generated Pitx2-deficient mice with the lacZ gene in the homeobox-containing exon of Pitx2. We were able to show that among three isoforms of Pitx2, Pitx2c shows asymmetrical expression whereas Pitx2a, Pitx2b and Pitx2c show symmetrical expression. In Pitx2(-)(/)(-) embryos there was an increase in mesodermal cells in the distal end of the left lateral body wall and an amnion continuous with the lateral body wall thickened in its mesodermal layer. These changes resulted in a failure of ventral body wall closure. In lung and heart in which Pitx2 is expressed asymmetrically, right pulmonary isomerism, atrioventricular canals with prominent swelling, and juxtaposition of the atrium were detected. The hearts failed to develop tricuspid and mitral valves and a common atrioventricular valve forms. Further, dysgenesis of the Pitx2(-)(/)(-) extraocular muscle and thickening of the mesothelial layer of cornea were observed in the ocular system where Pitx2 is expressed symmetrically, and these resulted in enophthalmos. The present study shows that Pitx2 expressed in various sites participates in morphogenesis through three types of actions: the involvement of asymmetric Pitx2 expression in the entire morphogenetic process of L-R asymmetric organs; the involvement of asymmetric Pitx2 expression in the regional morphogenesis of asymmetric organs; and finally the involvement of symmetric Pitx2 expression in the regional morphogenesis of symmetric organs.

Animals↗

PubMed1999

Mechanisms mediating the vasorelaxing action of eugenol, a pungent oil, on rabbit arterial tissue.

The inhibitory actions of eugenol on intracellular Ca2+ concentration ([Ca2+]i) and the contractions induced by excess extracellular K+ concentration ([K+]o) in rabbit thoracic aorta were investigated. Application of excess [K+]o solution (30-90 mM) produced contraction and increased the intensity of the Ca2+ fluorescence signal. Pretreatment with eugenol (> or =0.1 mM) reduced both the amplitude of contraction and the intensity of the Ca2+ fluorescence signal, but the contraction was more strongly affected than the [Ca2+]i. Application of eugenol (0.3 mM) to tissue precontracted by 90 mM [K+]o solution (immediately after the removal of the 90 mM [K+]o solution) slowed the decay of the [Ca2+]i signal, but it did not change the rate of relaxation. Carbonyl cyanide m-chlorophenylhydrozone (10 microM), a mitochondrial metabolic inhibitor, produced a reduction in tension despite a slight increase in [Ca2+]i when applied to muscle precontracted by 90 mM [K+]o solution. These results indicate that eugenol relaxes the rabbit thoracic aorta while suppressing the Ca2+-sensitivity and both the uptake and extrusion mechanisms for Ca2+. To judge from the similarities between its actions and those of metabolic inhibitors, eugenol may produce its actions at least partly through metabolic inhibition.

Animals↗