Biomedical subjects

A Tada

Publications and source records attributed to A Tada.

At least 37 records · Page 2Linked to original sources

PubMed2000

The melanocortin-1 receptor is a key regulator of human cutaneous pigmentation.

The cloning and characterization of the human melanocortin-1 receptor (MC1R) and the demonstration that normal human melanocytes respond to the melanocortins, alpha-melanocyte stimulating hormone (alpha-MSH) and adrenocorticotrophic hormone (ACTH), with increased proliferation and eumelanogenesis had put an end to a long-standing controversy about the role of melanocortins in regulating human cutaneous pigmentation. We have shown that alpha-MSH and ACTH bind the human MC1R with equal affinity, and are equipotent in their mitogenic and melanogenic effects on human melanocytes. We also showed that the activation of the MC1R is important for the melanogenic response of human melanocytes to ultraviolet radiation (UVR). The MC1R is also the principal mediator of the inhibitory effects of agouti signaling protein (ASP) on melanogenesis. Expression of the MC1R is subject to regulation by its own ligands alpha-MSH and ACTH, as well as by UVR and endothelin-1. Recent studies that we conducted on the expression of MC1R variants by human melanocytes and the implications of these variants on the function of the MC1R revealed the following. Human melanocytes homozygous for Arg160Trp mutation in the MC1R demonstrated a significantly reduced response to alpha-MSH. Also, this culture responded poorly to ASP and exhibited an exaggerated cytotoxic response to UVR. Another culture, which was homozygous for Val92Met mutation in the MC1R, demonstrated a normal response to alpha-MSH. Heterozygous mutations that are frequently expressed in various melanocyte cultures did not disrupt MC1R function. These results begin to elucidate the significance of MC1R variants in the function of the receptor. Our data emphasize the significance of a normally functioning MC1R in the response of melanocytes to melanocortins, ASP, and UVR.

Agouti Signaling Protein↗

PubMed2000

[Improvement of a case of broncholithiasis after spontaneous lithoptysis].

A 53-year-old woman was admitted for recurrent hemoptysis and cough. The chest radiograph showed an infiltrative shadow in the left upper region. Chest tomogram and CT scan showed a small calcification and consolidation in the left upper lobe. Fiberoptic bronchoscopy revealed fresh hemorrhage from the left upper bronchus but no broncholith or bleeding point were detected. Since the symptoms had disappeared by 10 days after admission, the patient was discharged and followed up as an outpatient. Three weeks later, she spontaneously expectorated a stone 3 mm in maximum diameter, with an irregular surface. Analysis revealed that the stone's composition was 56% of calcium phosphate and 44% of calcium carbonate. Hemoptysis seemed to have been caused by the broncholith, which had originated as a calcification of a peribronchial lymph node that subsequently eroded its way into the airway. After lithoptysis, no recurrence has been observed.

Bronchi↗

PubMed1999

The melanocortin-1 receptor and human pigmentation.

alpha-Melanocyte stimulating hormone (alpha-MSH) is known to be the main physiologic regulator for integumental pigmentation of various vertebrate species. However, the role of alpha-MSH and related melanocortins in the regulation of human cutaneous pigmentation is only beginning to be understood. Cloning of the melanocortin-1 receptor (MC1R), and the feasibility of establishing normal human epidermal melanocyte cultures have made it possible to demonstrate direct and specific biological effects of alpha-MSH on these cells. It is now recognized that both alpha-MSH and ACTH have similar mitogenic and melanogenic effects on human epidermal melanocytes. These effects are mediated by binding of these hormones to the specific MC1R that recognizes them both with similar affinity. Human MC1R is homologous to its mouse counterpart in that its activation leads to stimulation of eumelanin synthesis. MC1R is also the binding site for agouti signaling protein (ASP), the product of the agouti locus. Human epidermal melanocytes respond to purified recombinant mouse or human ASP, with a reduction in basal tyrosinase activity, and complete abrogation of the mitogenic and melanogenic effects of alpha-MSH. These results suggest that ASP induces pheomelanin synthesis by competing with alpha-MSH for binding to the MC1R. This receptor seems to be subject to regulation by a variety of paracrine and/or autocrine factors that are synthesized in response to exposure of the skin to ultraviolet radiation (UVR). Activation of MC1R seems to be pivotal for UV-induced melanogenesis, since stimulation of the cAMP pathway plays a key role in the melanogenic response of human epidermal melanocytes. The melanogenic response to UVR might be influenced by the presence of allelic variants of the MC1R gene. Allelic variants have been identified and shown to be associated with red hair, poor tanning ability, and possibly melanoma. The possible influence of these variants on the function of the MC1R needs to be investigated, in order to understand the physiological consequence of these mutations. Also, the interaction of alpha-MSH with other factors that are known to affect pigmentation needs to be better understood in order to define the role possible of this hormone and its receptor in acquired human cutaneous hyper- or hypopigmentation.

Agouti Signaling Protein↗

PubMed1999

Participation of the melanocortin-1 receptor in the UV control of pigmentation.

The cloning of the melanocortin-1 receptor (MC1R) gene from human melanocytes and the demonstration that these cells respond to the melanocortins alpha-melanocyte stimulating hormone (alpha-MSH) and adrenocorticotropic hormone (ACTH) with increased proliferation and melanogenesis have renewed the interest in investigation the physiological role of these hormones in regulating human pigmentation. Alpha-melanocyte stimulating hormone and ACTH are both synthesized in the human epidermis, and their synthesis is upregulated by exposure to ultraviolet radiation (UVR). Activation of the MC1R by ligand binding results in stimulation of cAMP formation, which is a principal mechanism for inducing melanogenesis. The increase in cAMP is required for the pigmentary response of human melanocytes to UVR, and for allowing them to overcome the UVR-induced G1 arrest. Treatment of human melanocytes with alpha-MSH increases eumelanin synthesis, an effect that is expected to enhance photoprotection of the skin. Population studies have revealed more than 20 allelic variants of the MC1R gene. Some of these variants are overexpressed in individuals with skin type I or II, red hair, and poor tanning ability. Future studies will aim at further exploration of the role of these variants in MC1R function, and in determining constitutive human pigmentation, the response to sun exposure, and possibly the susceptibility to skin cancer.

Alleles↗

PubMed1999

Caries risk factors among three-year old children in Chiba, Japan.

In order to predict the factors which affect the occurrence of dental caries in children after the age 18-months, we analyzed the relationship between the increment of the decayed, missing, and filled teeth (dmft) in children from 18-months to three-years of age and caries risk factors. Subjects were 392 infants who received both an 18-month-old check-up and a three-year-old check-up in Chiba city. Stepwise multiple logistic regression analyses were used to analyze the results with the increment of the dmft by various combinations of independent variables (sex, order of birth, sweets intake, beverage intake, tooth brushing and feeding). The most predictive factors for the increment of the dmft in upper anterior and molar were "breast feeding" and "bottle feeding" respectively. From these results, we concluded that bottle feeding and breast feeding were the risk factors for the increment of the dmft from the age of 18-months to three years.

Child, Preschool↗

PubMed1999

Quantification of two aromatic amine mutagens, PBTA-1 and PBTA-2, in the yodo river system.

The levels of two aromatic amine mutagens, 2-[2-(acetylamino)-4-[bis(2-methoxyethyl)amino]-5-methoxyphenyl]-5-am ino-7-bromo-4-chloro-2H-benzotriazole (PBTA-1) and 2-[2-(acetylamino-4-[N-(2-cyanoethyl)ethylamino]-5-methoxyphenyl]-5-a mino-7-bromo-4-chloro-2H-benzotriazole (PBTA-2), were quantitatively analyzed in the Yodo River system in Japan. The river water samples were collected at nine sampling sites from the Yodo River system twice or three times between May and July in 1997. PBTA-1 and PBTA-2 in the river water samples were concentrated on blue rayon columns, partially purified by high-performance liquid chromatography (HPLC) on reverse-phase columns, then quantified by HPLC with an electrochemical detector. The amounts of PBTA-1 and PBTA-2 in the water samples were < 0.01-1.91 and < 0.01-2.25 ng/L, respectively. High levels of PBTA-1 and PBTA-2 were detected in the samples collected within 4 km downstream of two sewage plants, which are located along the banks of the Nishitakase River, a tributary of the Yodo River system, and these samples showed stronger mutagenicity in Salmonella typhimurium YG1024 with S9 mix than the other water samples. On the other hand, the river water samples from upstream of the sewage plant were weakly or not mutagenic and PBTA-1 and PBTA-2 were not detected. These results confirmed that a major source of PBTA-1 and PBTA-2 in the Yodo River system is effluent from the sewage plants and that discharged mutagens, including PBTA-1 and PBTA-2, are diluted and/or decomposed while moving down the Yodo River system.

Chromatography, High Pressure Liquid↗

PubMed1999

[Clinical evaluation of new quinolones as antituberculosis drugs].

Compared with the recent rapid advances in the diagnosis of tuberculosis, advances in the treatment of tuberculosis have been quite slow. For example, as long as six months are required for initial treatment, even with addition of pyrazinamide in the first two months to isoniazid, rifampicin, and streptomycin or ethambutol. Moreover, it is not always easy to treat patients who cannot receive standard agents including isoniazid and rifampicin due to adverse effects of these drugs or drug resistance. For these reasons, the development of new agents with potent antituberculosis activities and fewer adverse effects is urgently desired. However, at present, few new antituberculosis agents are being developed, and new quinolones are considered the most promising new antituberculosis agents due to their lack of cross-resistance to previously existing antituberculosis agents, their excellent in vitro and in vivo antituberculous activities, and good pharmacokinetics. We therefore reviewed experimental studies and clinical reports useful for evaluation of potential clinical use of new quinolones as antituberculosis drugs. Our conclusions are summarized below: 1) Of nine new quinolones on the market, ofloxacin, ciprofloxacin, aparfloxacin and levofloxacin have excellent in vitro and in vivo antituberculous activities without cross-resistance to previously existing antituberculosis agents. 2) Ofloxacin appears to be useful clinically for intractable multidrug-resistant tuberculosis. The incidence and severity of adverse effects of ofloxacin were very low on longterm administration. 3) Ofloxacin resistance emerged from two to four months after initiation of administration of ofloxacin, and ofloxacin exhibited cross-resistance to other new quinolones. 4) The usefulness of new quinolones for initial treatment of tuberculosis is unclear. 5) New quinolones should be used to treat patients with drug-resistant tuberculosis and those patients for whom adverse effects have limited the use of standard agents. However, monotherapy with new quinolones is not recommended, due to the significant risk of emergence of quinolone resistance. 6) Not only ofloxacin, ciprofloxacin, sparfloxacin and levofloxacin, which are on the market, but also gatifloxacin, CS-940, Du-6859a and other newly developed new quinolones are candidates for new antituberculosis agents. However, careful study not only of antituberculous activities and pharmacokinetic but also drug interactions and chronic cumulative toxicities due to long-term administration are needed prior to clinical application of these drugs.

Anti-Infective Agents↗

PubMed1999

[Serum soluble interleukin-2 receptor in patients with pulmonary mycobacterial diseases].

Serum soluble interleukin-2 receptor (sIL-2R) levels were measured in patients with untreated pulmonary tuberculosis (24 cases), patients with multidrug-resistant intractable pulmonary tuberculosis (7 cases) and patients with pulmonary non-tuberculous mycobacteriosis (27 cases). Serum sIL-2R levels were elevated in patients with pulmonary mycobacterial diseases and were elevated in untreated pulmonary tuberculosis patients than in other patients. In patients with new tuberculosis, serum sIL-2R levels were higher in patients with extensive lesions. Serum sIL-2R level showed significant positive correlation with serum C-reactive protein level and erythrocyte sedimentation rate, and significant negative correlation with serum albumin level. In patients with intractable tuberculosis and patients with non-tuberculous mycobacteriosis, serum sIL-2R levels were lower than in patients with new tuberculosis. Even in patients with extensive lesions, serum sIL-2R levels were not elevated. Lower levels of serum sIL-2R, marker of immunocompetent cell activity, suggested that immunocompetent cell activity was suppressed in intractable tuberculosis and in non-tuberculous mycobacteriosis.

Adult↗

PubMed1999

[A case of elderly patient with pulmonary tuberculosis considered to be caused by exogenous reinfection].

A 84-year-old woman presented with chronic febrile illness and anorexia from June 1998. She was diagnosed as pulmonary tuberculosis and was admitted to our hospital in August 1998. Her sputum smear was Gaffky 2, and the type of chest radiograph was b III 3. By family contact examination in August 1998, chest radiological examinations of her husband, a 86-year-old man, showed consolidation in middle lobe, right pleural effusion and two calcified mediastinal lymphnodes. He was diagnosed as pulmonary tuberculosis complicated with pleurisy. He had poor controlled diabetes mellitus. Tubercle bacilli isolated from their sputa showed the same pattern in restriction fragment length polymorphism analysis. Pulmonary tuberculosis of the husband was considered to be caused by exogenous reinfection.

Aged↗

PubMed1998

Crescentic glomerulonephritis developing 3 months after autologous peripheral blood stem cell transplantation for non-Hodgkin's lymphoma.

A 64-year-old woman underwent an ileocecal resection for ileus. The specimen revealed a diffuse large B cell lymphoma. The diagnosis was stage IIA non-Hodgkin's lymphoma. She received chemotherapy with the CHOP-etoposide regimen, resulting in partial remission. High-dose etoposide was used for PBSC mobilization before auto-PBSCT. Conditioning was ranimustine, carboplatin, etoposide and cyclophosphamide. Her renal function deteriorated gradually, starting 3 months post-PBSCT. Eight months post-transplant, serum creatine concentration was 7.1 mg/dl, and BUN was 59.2 mg/dl. Her hemoglobin concentration decreased to 5.3 g/dl, with no evidence of hemolysis. Renal biopsy revealed fibrous crescent formations in glomeruli, and mononuclear cell infiltration in interstitial spaces. Renal injury in this patient differs from BMT nephropathy, which is similar to hemolytic uremic syndrome, and represents another type of late renal injury after PBSCT.

Female↗

PubMed1998

Decreased myocardial 123I-MIBG uptake in Parkinson's disease.

We studied myocardial 123I-metaiodobenzylguanidine (MIBG) accumulation in 12 patients with Parkinson's disease (PD). MIBG is an analog of norepinephrine (NE) and a tracer for sympathetic neuron integrity and function. MIBG uptake of the myocardium was significantly lower in PD than in controls. The heart to mediastinum ratio (H/M) was calculated by using the average count per pixel for the heart and mediastinum. In PD, H/M was lower than in controls (P<0.0001), while the washout ratio of the heart was higher (P<0.001). A decrease in myocardial accumulation of MIBG was observed in the early stage of PD. This suggests that the measurement of MIBG may help the diagnosis of early PD, and the causative factor underlying in PD may be operating the NE neuron as well as dopamine neuron.

3-Iodobenzylguanidine↗

PubMed1998

[Clinical analysis of foreign patients with tuberculosis found in Chugoku-Shikoku area].

In this study, we investigated 45 foreign patients who had been diagnosed as having tuberculosis in Chugoku-Shikoku area during the past 12 years. Regarding regional characteristics, in Hiroshima prefecture an epidemic of tuberculosis was experienced among patients coming from South America, but antituberculous therapy was performed for 87% of the patients because of the high coverage of the health insurance scheme. But in Okayama prefecture, most of the patients were female and came from Asian countries, such as, the Philippines. Antituberculous therapy was not performed for nine patients because of no coverage of the health insurance scheme. In the other prefectures, only a few cases of tuberculosis were experienced, but in Yamaguchi prefecture two of three foreign patients were multidrug-resistant tuberculosis.

Adolescent↗

PubMed1998

Endothelin-1 is a paracrine growth factor that modulates melanogenesis of human melanocytes and participates in their responses to ultraviolet radiation.

Endothelin (ET)-1, alpha-melanocyte stimulating hormone (alpha-melanotropin; alpha-MSH), and basic fibroblast growth factor (bFGF) are keratinocyte-derived factors that interact synergistically to stimulate human melanocyte proliferation. ET-1 has a dose-dependent mitogenic effect on human melanocytes and a biphasic effect on melanogenesis: a stimulatory effect at subnanomolar concentrations, and an inhibitory effect at concentrations equal to or higher than 1 nM. Human melanocytes express ET B receptors. Brief treatment of melanocytes with ET-1 caused up-regulation of alpha-MSH receptor mRNA but did not alter ET B receptor mRNA level. ET-1 modulates the response of human melanocytes to UV rays (UVRs). Treatment of melanocytes with 10 nM ET-1 immediately after exposure to UVRs enabled them to overcome the G1 growth arrest. However, ET-1 did not inhibit p53 accumulation or p21(Waf-1/SDI-1/Cip-1) overexpression, nor did it reverse the hypophosphorylated state of pRb or the reduction in Bcl2 level in irradiated melanocytes. These results substantiate the role of ET-1 as a paracrine regulator that modulates the response of human melanocytes to UVRs.

Cell Division↗

PubMed1997

Transforming growth factor beta1 increases the expressions of high molecular weight tropomyosin isoforms and vinculin and suppresses the transformed phenotypes in human lung carcinoma cells.

Exposure of the human lung carcinoma cell line, A549 cells, to transforming growth factor beta1 (TGFbeta1) resulted in an alteration in the morphology from epithelial-like to fibroblastic flat cells. Immunofluorescent study revealed that microfilament organization was partially restored in the TGFbeta1-treated cells. We also investigated the effects of TGFbeta1 on the transformed phenotypes including the anchorage-independent growth and invasive ability of A549 cells and found that the phenotypes were strikingly suppressed in TGFbeta1-treated A549 cells. Accompanying these changes, the levels of the expression of high molecular weight tropomyosin (TM) isoforms, especially TM1 and TM2, were significantly increased in the TGFbeta1-treated cells. The expression level of vinculin was also increased in these cells. These results suggest that the increased tropomyosin and vinculin syntheses may be involved in the suppression of the transformed phenotypes of A549 cells.

Actins↗

PubMed1997

Different sympathetic-parasympathetic interactions on sinus rate and atrioventricular conduction in dog hearts.

We investigated the sympathetic-parasympathetic interactions involved in SA nodal pacemaker activity and AV conductivity in the anesthetized dog heart. Stimulation of the intracardiac parasympathetic nerves to the SA nodal region (SAPS) and stimulation of the intracardiac parasympathetic nerves to the AV nodal region (AVPS) induced negative chronotropic and dromotropic responses, respectively. Cardiac sympathetic stimulation, aminophylline, 3-isobutyl-1-methylxanthine (IBMX, a relatively pure nonselective phosphodiesterase inhibitor) and methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)-p iridine-5-carboxylate (Bay k 8644, a Ca2+ channel agonist) increased sinus rate and decreased AV conduction time. Sympathetic stimulation augmented the negative chronotropic response to SAPS but not the negative dromotropic response to AVPS, IBMX augmented both responses, Bay k 8644 augmented the chronotropic response and attenuated the dromotropic response, and aminophylline did not affect the chronotropic response to SAPS and inhibited the dromotropic response to AVPS. Additionally, when Bay k 8644 directly given via the AV node artery decreased AV conduction time, it attenuated the negative dromotropic response to AVPS and carbachol injected into the AV node artery. These results suggest that the differential sympathetic-parasympathetic interactions on sinus rate and AV conduction are at least partly induced by an interaction between changes in slow inward Ca2+ current or intracellular Ca2+ and the cardiac effects of acetylcholine in the heart in situ.

1-Methyl-3-isobutylxanthine↗

PubMed1997

Agouti signaling protein inhibits melanogenesis and the response of human melanocytes to alpha-melanotropin.

In mouse follicular melanocytes, the switch between eumelanin and pheomelanin synthesis is regulated by the extension locus, which encodes the melanocortin-1 receptor (MC1R) and the agouti locus, which encodes a novel paracrine-signaling molecule that inhibits binding of melanocortins to the MC1R. Human melanocytes express the MC1R and respond to melanotropins with increased proliferation and eumelanogenesis, but a potential role for the human homolog of agouti-signaling protein, ASIP, in human pigmentation has not been investigated. Here we report that ASIP blocked the binding of alpha-melanocyte-stimulating hormone (alpha-MSH) to the MC1R and inhibited the effects of alpha-MSH on human melanocytes. Treatment of human melanocytes with 1 nM-10 nM recombinant mouse or human ASIP blocked the stimulatory effects of alpha-MSH on cAMP accumulation, tyrosinase activity, and cell proliferation. In the absence of exogenous alpha-MSH, ASIP inhibited basal levels of tyrosinase activity and cell proliferation and reduced the level of immunoreactive tyrosinase-related protein-1 (TRP-1) without significantly altering the level of immunoreactive tyrosinase. In addition, ASIP blocked the stimulatory effects of forskolin or dibutyryl cAMP, agents that act downstream from the MC1R, on tyrosinase activity and cell proliferation. These results demonstrate that the functional relationship between the agouti and MC1R gene products is similar in mice and humans and suggest a potential physiologic role for ASIP in regulation of human pigmentation.

Agouti Signaling Protein↗

PubMed1997

[Successful treatment for advanced and refractory chronic lymphocytic leukemia with fludarabine phosphate].

53-year-old man with chronic lymphocytic leukemia resistant to alkylating agent containing regimens, was treated with fludarabine phosphate. Hematological data before the administration of fludarabine phosphate was as follows: RBC 216 x 10(4)/microliter, Hb 7.7 g/dl, WBC 69,400/microliter (lymphocyte 96%), PLT 0.2 x 10(4)/microliter. Bone marrow was fully occupied with lymphocytes. Red blood cells and platelets transfusions were frequently required. Fludarabine phosphate was administered at a dose of 40 mg (23 mg/m2) intravenously for 5 days every 4 weeks. After the start of the therapy, peripheral lymphocyte counts were markedly decreased and recovery of normal hematopoiesis was observed in bone marrow. Any transfusions were no longer necessary. Fludarabine phosphate may be active even for advanced, refractory and terminal stage chronic lymphocytic leukemia.

Antineoplastic Agents↗

PubMed1996

32P-Postlabeling analysis of a DNA adduct, an N2-acetyl derivative of guanine, formed in vitro by methylglyoxal and hydrogen peroxide in combination.

Methylglyoxal is a direct-acting mutagen in Salmonella typhimurium TA100 and its mutagenicity is markedly enhanced in the presence of hydrogen peroxide. In addition, a mixture of methylglyoxal and hydrogen peroxide reacts with 2'-deoxyguanosine to form N2-acetyl-2'-deoxyguanosine. We examined whether the guanine residues in DNA were acetylated by methylglyoxal in the presence of hydrogen peroxide using the 32P-postlabeling method. First, N2-acetyl-2'-deoxyguanosine 3'-monophosphate and N2-acetyl-2'-deoxyguanosine 3,5'-diphosphate were chemically synthesized as standard compounds for the analysis. Then calf thymus DNA (3.24 micromol) was treated with methylglyoxal (64.8 micromol) at pH 7.4 for 3 h at 37 degrees C, and subsequently with hydrogen peroxide (64.8 micromol) at 37 degrees C for 2 h. The adduct formation was analyzed using HPLC in combination with the 32P-postlabeling method under the standard conditions. N2-Acetyl-2'-deoxyguanosine was detected at levels of 2/10(6) nucleotides in double-stranded DNA and 1/10(5) nucleotides in single-stranded DNA. The estimated limit of detection by our method was 3 per 10(8) nucleotides.

Acetylation↗