Biomedical subjects

T Yamauchi

Publications and source records attributed to T Yamauchi.

At least 127 records · Page 7Linked to original sources

PubMed2000

Hyperthyroidism in a patient with TSH-producing pituitary adenoma coexisting with thyroid papillary adenocarcinoma.

A 27-year-old woman who presented with a left thyroid nodule was found to have hyperthyroidism caused by a syndrome of inappropriate secretion of TSH. The levels of free T3, free T4 and TSH were 9.50 pg/mL, 4.05 ng/dL and 2.16 microU/mL, respectively. Magnetic resonance imaging of the head revealed a pituitary macroadenoma. The TSH response to TRH stimulation was normal and responses of other anterior pituitary hormones to stimulation tests were also normally preserved. Administration of octreotide with iodine successfully reversed hyperthyroidism prior to total resection of pituitary adenoma, which was followed by hemithyroidectomy of the left thyroid five months later. Histologically, the resected pituitary adenoma was a TSH-producing adenoma (TSH-oma) and the thyroid nodule was a papillary adenocarcinoma. Serum TSH diminished to undetectable levels immediately following pituitary adenomectomy but gradually normalized over nine months. Coexistence of a TSH-oma with thyroid cancer is very rare and only two similar cases have previously been documented. This combination raises the possibility that TSH may be involved in tumorigenesis in the thyroid gland.

Adenocarcinoma, Papillary↗

PubMed2000

Disruption of insulin receptor substrate 2 causes type 2 diabetes because of liver insulin resistance and lack of compensatory beta-cell hyperplasia.

To investigate the role of insulin receptor substrate (IRS)-2 in vivo, we generated IRS-2-deficient mice by gene targeting. Although homozygous IRS-2-deficient mice (IRS-2-/- mice) had a body weight similar to wild-type mice, they progressively developed type 2 diabetes at 10 weeks. IRS-2-/- mice showed insulin resistance and a defect in the insulin-stimulated signaling pathway in liver but not in skeletal muscle. Despite insulin resistance, the amount of beta-cells was reduced to 83% of that in wild-type mice, which was in marked contrast to the 85% increase in the amount of beta-cells in IRS-1-deficient mice (IRS-1-/- mice) to compensate for insulin resistance. Thus, IRS-2 plays a crucial role in the regulation of beta-cell mass. On the other hand, insulin secretion by the same number of cells in response to glucose measured ex vivo was significantly increased in IRS-2-/- mice compared with wild-type mice but was decreased in IRS-1-/- mice. These results suggest that IRS-1 and IRS-2 may play different roles in the regulation of beta-cell mass and the function of individual beta-cells.

Animals↗

PubMed2000

Induction of endothelin-1 expression by glucose: an effect of protein kinase C activation.

Enhanced actions or levels of endothelin-1 (ET-1), a potent vasoconstrictor, have been associated with decreased blood flow in the retina and peripheral nerves of diabetic animals and may be related to the development of pathologies in these tissues. Hyperglycemia has been postulated to increase ET-1 secretion in endothelial cells. We have characterized the mechanism by which elevation of glucose is increasing ET-1 mRNA expression in capillary bovine retinal endothelial cells (BREC) and bovine retinal pericytes (BRPC). Elevation of glucose, but not mannitol, from 5.5 to 25 mmol/l for 3 days increased membranous protein kinase C (PKC) activities and ET-1 mRNA in parallel levels by 2-fold in BREC and BRPC. These effects were reversed by decreasing glucose levels to 5.5 mmol/l for an additional 2 days. Glucose-induced ET-1 overexpression was inhibited by a general PKC inhibitor, GF109203X, and a mitogen-activated protein kinase kinase inhibitor, PD98059, but not by wortmannin, a phosphatidylinositol 3-kinase inhibitor. By immunoblot analysis, PKC-beta2 and -delta isoforms in BREC were significantly increased relative to other isoforms in the membranous fractions when glucose level was increased. Overexpression of PKC-beta1 and -delta isoforms but not PKC-zeta isoform by adenovirus vectors containing the respective cDNA enhanced in parallel PKC activities, proteins, and basal and glucose-induced ET-1 mRNA expression by at least 2-fold. These results showed that enhanced ET-1 expression induced by hyperglycemia in diabetes is partly due to activation of PKC-beta and -delta isoforms, suggesting that inhibition of these PKC isoforms may prevent early changes in diabetic retinopathy and neuropathy.

Animals↗

PubMed2000

Learning categories composed of varying instances: the effect of classification, inference, and structural alignment.

The members of a natural category are not usually identical in their appearance, although at some level they can be described as having features in common. For example, birds have wings, but the actual appearance of their wings varies from one bird to another. To examine the effect of this feature variation on category acquisition, subjects in three experiments were asked to learn categories in which individual features were depicted with several different instances. The results of the experiments indicated that subjects had significant difficulty learning these categories when they were given a standard classification learning task. In contrast, subjects were able to acquire the same categories when they were given an inference learning task, in which they learned the categories by predicting a missing feature of a stimulus given the category label and information about the other features. Finally, subjects who were allowed to compare stimuli during learning were able to learn the categories. These results suggest that a common description of different instances emerges in the process of aligning stimuli.

Attention↗

PubMed2000

Torsade de pointes associated with hypokalemia after anthracycline treatment in a patient with acute lymphocytic leukemia.

Severe dose-dependent anthracycline cardiotoxicity is reported to cause myocardial damage resulting in congestive heart failure. However, torsade de pointes, a life-threatening arrhythmia caused by chronic anthracycline cardiotoxicity, has not been reported previously. A 16-year-old girl who developed torsade de pointes after 6 months of chemotherapy for acute lymphocytic leukemia (French-American-British classification L2) is described. When the patient was readmitted to the hospital because of syncope, peripheral blood and bone marrow analysis indicated a relapse. In addition, the patient was hypokalemic. Twenty-four-hour ambulatory electrocardiographic monitoring demonstrated QT prolongation and an episode of torsade de pointes. The electrocardiographic changes and arrhythmia improved after correction of the hypokalemia. An inverse correlation between leukocyte count and hypokalemia was observed. The patient died from pulmonary hemorrhage. Autopsy examination demonstrated myocardial degeneration consistent with damage induced by antineoplastic antibiotics. The cumulative dose of anthracycline and anthraquinone was less than the conventional dose limit associated with chronic cardiotoxicity, even for children who are more sensitive to anthracyclines. Torsade de pointes can occur in the setting of chronic anthracycline cardiotoxicity. Therefore, children or young adults who are more sensitive to anthracycline need careful observation that includes electrolyte monitoring, especially for potassium.

Adolescent↗

PubMed2000

Abstinence from drink ameliorated cerebral blood flow and vasoreactivity in patients with chronic alcoholism.

High dose ethanol consumption is a risk factor for both ishemic and hemorrhagic cerebrovasucular disease. This link between heavy drinkers and the risk factor of stroke has been considered as hypertension, liver dysfunction, abnormality of platelet function or other unknown mechanisms. Recently some of the experimental study suggest that direct action of ethanol on the inhibition of the synthesis/release of nitric oxide from endothelium and neurons may contribute to this link. Few studies in this field, however, were performed clinically. We examined cerebral blood flow (CBF) and vaso-reactivity in the patients with chronic alcoholism on abstinence from drink. CBF of nine male patients were measured by use of stable Xe-CT method before and after acetazolamide load. Regional CBF increased in second measurement after abstinence, but there were no significant changed statistically. However, %vaso-reactivity in right ACA and MCA significantly improved. We considered that large brain vessels dilated then small vessels could response to acetazolamide.

Acetazolamide↗

PubMed2000

[Clinical studies on renal pelvic and ureteral tumors].

Clinical studies were performed on 35 patients with renal pelvic and/or ureteral cancer treated at Kitano Hospital between 1988 and 1997. They consisted of 17 renal pelvic cancers, 17 ureteral cancers and 1 renal pelvic and ureteral cancer. Twenty-nine patients were males and six were females, and their age ranged from 41 to 82 years old (average: 62.2). Histologically, 34 were transitional cell carcinoma and 1 was adenocarcinoma. Pathological stage of the tumor was pTa in 34.3%, pT1 in 14.3%, pT2 in 11.4%, pT3 in 37.1%, and pT4 in 2.9%, and grade of the tumor G1 in 11.8%, G2 in 58.8% and G3 in 29.4%. Eighteen patients (51%) had or developed bladder cancer, which preceded the diagnosis of cancer of upper urinary tract in 2 cases, coexisted in 4 cases and developed subsequently in 12 cases. The overall cause-specific survival rate was 91.3% at 1 year, 83.8% at 3 years and 79.4% at 5 years. Tumor stage, grade, lymph node metastasis and vascular invasion had impact on survival.

Adult↗

PubMed2000

[Traumatic cardiac tamponade due to the nail stabbing].

A 45-year-old man was admitted to our hospital complaining of mild chest pain. The stab wound on the chest was very small and the nail had been completely buried under the skin. Emergency operation was mandatory for cardiac tamponade by the nail stabbing. Contused right ventricular wall was repaired using Teflon felt under cardiopulmonary bypass. It was important to have a suspicion as cardiac tamponade, when the patient showed uncertain hypotension.

Cardiac Tamponade↗

PubMed2000

Medical management of acute bacterial sinusitis. Recommendations of a clinical advisory committee on pediatric and adult sinusitis.

Acute sinusitis is commonly encountered in clinical practice and treated in the primary care setting. The clinician should recognize the subtle clinical presentation of acute bacterial sinusitis and initiate appropriate, aggressive treatment. Other upper respiratory tract disorders can confound the accurate diagnosis and appropriate treatment of sinusitis. Variable patterns of microbial resistance and antibiotic susceptibility and the dissociation between in vitro findings and clinical efficacy are a treatment challenge. This report is a comprehensive review of the pathophysiology and diagnosis of acute sinusitis, infectious agents, treatment methods, antibiotic resistance patterns, and costs associated with the management of sinusitis. Treatment algorithms are presented for adult and pediatric sinusitis.

Acute Disease↗

PubMed2000

Protective effect of bradykinin against glutamate neurotoxicity in cultured rat retinal neurons.

PURPOSE: To identify the localization and expression of bradykinin (BK)-B2 receptors in rat retina and examine the effects of BK on glutamate-induced neurotoxicity using cultured rat retinal neurons. METHODS: An immunohistochemical study using a specific antibody against BK-B2 receptor was performed with rat retina. Primary cultures were obtained from the retina of fetal rats (gestation day 17-19). Expression of BK-B2 receptor mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR) using total RNA obtained from cultured retinal neurons. Cultured cells were exposed to glutamate (1 mM) for 10 minutes and followed by incubation in glutamate-free medium for 1 hour. The effects of BK were assessed by simultaneous application of BK with glutamate. The neurotoxic effects on retinal cultures were quantitatively assessed by the trypan blue exclusion method. RESULTS: Immunohistochemical study demonstrated that BK-B2 receptors were expressed in the ganglion cell, inner nuclear layers, and outer nuclear layers. Furthermore, BK-B2 receptor mRNA expression was observed in cultured retinal neurons. Cell viability was markedly reduced by 10-minute exposure to 1 mM glutamate followed by a 1-hour incubation in glutamate-free medium. Simultaneous application of BK at concentrations of 0.001 to 1 microM with glutamate demonstrated dose-dependent protection against glutamate neurotoxicity. The protective action of BK (1 microM) was inhibited by simultaneous application of BK-B2 receptor antagonist, Hoe140 (1 microM). Furthermore, 1 microM BK had protective effects on neurotoxicity induced by 1 microM ionomycin, a calcium ionophore, and sodium nitroprusside (SNP, 500 microM), a nitric oxide (NO)-generating agent. However, BK did not inhibit neurotoxicity induced by 3-morpholinosydnonimine (SIN-1, 10 microM), an NO and oxygen radical donor. CONCLUSIONS: These results suggest that BK-B2 receptors were distributed in rat retinas and cultured retinal neurons and that BK had a protective action against glutamate neurotoxicity through BK-B2 receptors in cultured retinal neurons. It is suggested that BK-induced protection against glutamate neurotoxicity took place downstream to NO generation and upstream to oxygen radical generation.

Adrenergic beta-Antagonists↗

PubMed2000

Controversies in the medical management of persistent and recurrent acute otitis media. Recommendations of a clinical advisory committee.

Streptococcus pneumoniae is the predominant bacterial pathogen associated with acute otitis media (AOM), causing an estimated 7 million cases annually in the United States. Bacterial resistance should be considered when selecting an antimicrobial agent for otitis media. Significant increases in drug-resistant S pneumoniae are documented worldwide, and less than 50% of S pneumoniae strains are fully susceptible to penicillin in some regions of the United States. Although amoxicillin is recommended for uncomplicated AOM, treatment guidelines should be flexible and adaptable, taking into consideration local and regional susceptibility patterns, the age of the patient, the frequency of prior infections, and the response to prior therapy. Resistant organisms are more prevalent in children younger than 2 years of age and in those who have recurrent or persistent AOM. Overdiagnosing AOM, selecting inappropriate empiric therapy, or both, leads to overuse and misuse of antibiotics and causes increased drug resistance. This article reviews persistent and recurrent AOM and discusses the pitfalls of diagnosis and the practical limitations of current treatment recommendations.

Acute Disease↗

PubMed2000

[Thoracoscopic major lung resection using a newly developed instrument retraction system and a voice-controlled robot].

We report a case of thoracoscopic major lung resection using a newly-developed instrument retraction system and a voice-controlled robot for lung cancer in a 72-year-old woman. The patient was referred to our department for further examination of an abnormal shadow on chest x-ray. A chest computed tomographic scan indicated a suspicion of malignancy. Bronchoscopic brush cytology revealed a lung cancer. Thoracoscopic middle lobectomy of the right lung with dissection of the mediastinal lymphnodes was successfully performed without a human assistance with no complications. The postoperative course was uneventful. Thoracoscopic major lung resection using an instrument retraction system and a voice-controlled robot may be feasible in selected cases.

Adenocarcinoma↗

PubMed2000

Clinico-epidemiology of hepatitis B viral infection in Northeastern Thailand.

Hepatitis B viral (HBV) infection is a common disease world wide. A study of clinico-epidemiology of HBV infection was conducted in 381 patients who seropositive for hepatitis B surface antigen (HBsAg) in Srinagarind Hospital, Khon Kaen University, Northeastern Thailand, during August 1997 to December 1998. 293 males, 88 females and their mean age was 30.96 +/- 12.78 years with a range from 15 to 77 years. The clinical features of acute hepatitis, chronic hepatitis, liver cirrhosis, hepatocellular carcinoma (HCC) and asymptomatic carrier were 2.36, 34.12, 4.99, 1.05 and 57.48% of cases. Possible routes for HBV transmission were family history of hepatitis, tattooing, intravenous drug addict and blood transfusion in 20.3, 11.3, 8.2 and 6.9% of cases, respectively. Signs of chronic liver disease were common in liver cirrhosis and HCC. Acute fulminating hepatitis was not found in this study.

Adolescent↗

PubMed2000

Ampullectomy of carcinoma of the papilla of vater in an elderly patient without jaundice.

A 79 year-old woman was admitted to Aioi City Hospital for a closer examination of hepatic dysfunction. A filling defect was observed at the distal end of the intrapancreatic common bile duct by computed tomography combined with drip infusion cholangiography. The diagnosis of adenoma with dysplasia at the papilla of Vater was obtained by a biopsy performed during duodenoscopy. As a result, we performed an ampullectomy. Histologic examination revealed a papillary adenocarcinoma which partly extended just beyond the muscle of Oddi. The patient made an uneventful recovery and was discharged on the 35th postoperative day. Here, based upon our experience, we discuss such problems as the accuracy of preoperative diagnosis and the indications for ampullectomy.

Adenocarcinoma, Papillary↗

PubMed2000

Improvement of interstitial cystitis symptoms and problems that developed during treatment with oral IPD-1151T.

PURPOSE: We examined the efficacy of Suplatast Tosilatedouble dagger (IPD-1151T), a new immunoregulator that suppresses helper T cell mediated allergic responses, including IgE production and eosinophilic inflammation for treating patients with interstitial cystitis. MATERIALS AND METHODS: A total of 14 women (average age 43.7 years) with interstitial cystitis, which was nonulcerative in 13 and ulcerative in 1, were treated with 300 mg. IPD-1151T orally daily for 12 months. All patients received laboratory assessments, including hematology (eosinophils and CD20 positive cells) and serum chemistry (IgE, and interleukin-4 (IL-4) and 5, and immunohistochemical analyses of urine leukocytes (CD45RO positive cells as a T cell marker) before treatment. These parameters were also measured 4 and 12 months after continuous treatment. The voiding chart, and interstitial cystitis symptom and problem indexes were evaluated before and after IPD-1151T treatment. RESULTS: IPD-1151T treatment for 1 year resulted in a significantly increased bladder capacity and decreased symptoms, such as urinary urgency, frequency and lower abdominal pain, in patients with nonulcerative interstitial cystitis. These effects also correlated with a reduction in blood eosinophils, CD20 positive cells and IgE, and urine CD45RO positive memory T cells. No major side effects were observed. CONCLUSIONS: Our study suggests that immunological responses are involved in the development of interstitial cystitis symptoms. IPD-1151T could be a new oral agent for treatment of voiding symptoms and bladder pain in patients with interstitial cystitis.

Adjuvants, Immunologic↗

PubMed2000

Clinico-epidemiology of hepatitis C viral infection in northeastern Thailand.

Hepatitis C virus (HCV) is responsible for a large number of cases of chronic liver disease worldwide. A study of clinico-epidemiology of HCV infection was conducted in 214 patients who were seropositive for antibody to HCV (anti-HCV) in Srinagarind Hospital, Khon Kaen University, northeastern Thailand, during August 1997 to December 1998. There were 199 males, 15 females and their mean age was 34.96 +/- 9.75 years with a range from 16 to 72 years. The clinical features of acute hepatitis, chronic hepatitis, liver cirrhosis, hepatocellular carcinoma (HCC) and asymptomatic HCV infection were 2, 115, 15, 2 and 80 cases. Risk factors for HCV acquisition were intravenous drug use (IVDU), tattooing and blood transfusion in 46.7, 32.2 and 18.8% of cases, respectively. 23.36% had a history of multiple risk factors while 28.9% had no history of risk factor exposure.

Adolescent↗

PubMed1999

Alleic variants of human melatonin 1a receptor: function and prevalence in subjects with circadian rhythm sleep disorders.

The human melatonin 1a (hMella) receptor gene was screened for mutations using genomic DNA samples from patients with circadian rhythm sleep disorders and control subjects by single strand conformational polymorphism analysis (SSCP). We found seven mutations, two of which predict amino acid changes R54W and A157V, respectively. The prevalence of the R54W variant and that of the A157V variant were several times more common in non-24-h sleep-wake syndrome subjects than among control subjects, although the incidence was not significant in our study group. When expressed in COS-7 cells, the R54W mutant receptor exhibited significantly reduced B(max) and slightly enhanced affinity (reduced K(d)) compared to the wild type receptor, while the A157V variant receptor showed similar binding characteristics to the wild type. The identification of variants in the hMella receptor will provide a useful tool for analyzing genetic predisposition toward various diseases related to melatonin function and to clarify the physiological role of melatonin receptors in humans.

Alleles↗

PubMed1999

Quantitative analysis of growth-related factors in human pituitary adenomas. Lowered insulin-like growth factor-I and its receptor mRNA in growth hormone-producing adenomas.

To elucidate the contribution of growth factors to the development, growth and behavior of human pituitary adenomas, the authors used competitive reverse transcription-polymerase chain reactions to quantify expression of mRNAs for growth factors extracted from pituitary adenomas. As previously diagnosed by endocrinologic evaluation, the pituitary adenomas in this study consisted of six prolactin-producing, six growth hormone (GH)-producing, four follicle-stimulating hormone producing and six nonfunctioning adenomas. The mRNAs examined included those for platelet-derived growth factor (PDGF) B-chain, transforming growth factor (TGF)-beta1, epidermal growth factor (EGF), basic fibroblast growth factor (bFGF) and insulin-like growth factor (IGF)-I and -II; proliferating cell nuclear antigen (PCNA) as an indicator of cell proliferation; and pituitary-specific transcription factor-1 (Pit-1) which is a nuclear transcription factor expressed in the anterior pituitary. All factors except the last were expressed in all adenomas, and expression of PDGF B-chain, TGF-beta1, EGF, bFGF and IGF-II did not differ between the four adenoma varieties. Pit-1 was expressed only in GH- and prolactin-producing adenomas. PCNA expression also showed no differences. However, IGF-I mRNA in GH-producing adenomas was significantly lower than in prolactin-producing and nonfunctioning adenomas despite high serum IGF-I levels (1121+/-253 ng/ml). The analysis on IGF-I receptor mRNA was significantly lowered in GH-producing adenoma compared with the other types of adenoma. These findings suggest that the attenuation of negative feedback through the pituitary GH-IGF-I axis may be involved in development of GH-producing adenoma.

Adenoma↗