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Biomedical subjects

N Yamaguchi

Publications and source records attributed to N Yamaguchi.

At least 307 records · Page 17Linked to original sources
PubMed1995

Implication of L-type Ca2+ channels in noncholinergic adrenal catecholamine secretion by endothelin-1 in vivo.

The aim of the present study was to investigate if either dihydropyridine-sensitive L-type Ca2+ channels or cholinergic receptor-mediated mechanisms are implicated in endothelin-1 (ET)-induced adrenal catecholamine (CA) secretion in anesthetized dogs. ET was locally administered to the left adrenal gland via the left adrenolumbar artery. Plasma CA concentrations in adrenal venous and aortic blood were determined by a high-performance liquid chromatography method. In the control group, local infusion (1 min, 0.5 ml/min) of ET (the fixed total dose of 0.5 microgram given to the gland or approximately 0.0197 microgram/kg of body weight) resulted in a sharp increase in the basal CA output, followed by a rapid decline, and a relatively slow secondary response lasted over a period of 15-30 min. In the second group treated with nifedipine (5 micrograms or approximately 0.207 microgram/kg) similarly administered 10 min before ET infusion, the ET-induced first steep increase in CA output was significantly attenuated by approximately 75% (P < 0.05, n = 6). In dogs similarly receiving either pentolinium (1 mg or approximately 0.041 mg/kg) or atropine (0.5 mg or approximately 0.018 mg/kg), the ET-induced CA response remained unchanged. The results indicate that ET-induced adrenal CA release was largely mediated by the activation of dihydropyridine-sensitive L-type Ca2+ channels. Furthermore, neither nicotinic nor muscarinic receptors were functionally implicated in the CA response to ET. The study suggests the existence of noncholinergic mechanisms involved in the secretory action of ET on the adrenal medulla in the dog in vivo.

Adrenal Glands↗
PubMed1995

Effect of hepatic vagotomy on plasma catecholamines during exercise-induced hypoglycemia.

The existence of a hepatosympathetic reflex active during insulin-induced hypoglycemia has recently been reported. The purpose of the present investigation was to test the hypothesis that the liver, through the afferent innervation of the vagus nerve, contributes to plasma epinephrine and norepinephrine responses during exercise-induced hypoglycemia. Hepatic vagotomized and sham-operated rats were killed at rest or after 30, 60, and 120 min of running exercise (26 m/min, 0% grade). At the end of the 120-min exercise period, liver glycogen, glucose, and insulin levels measured in the portal and peripheral plasma were all significantly reduced (P < 0.05) while epinephrine and norepinephrine concentrations, beta-hydroxybutyrate, lactate, and portal and peripheral glucagon plasma levels were all significantly increased (P < 0.05). However, no significant differences were observed between hepatic vagotomized and sham-operated rats at rest and after exercise for the metabolic and hormonal responses. These results suggest that if a hepatosympathetic reflex is active during an exercise-induced hypoglycemia situation, then this contribution is probably hidden by more important regulatory mechanisms.

3-Hydroxybutyric Acid↗
PubMed1995

Differences in down-regulation of glucocorticoid receptor mRNA by cortisol, prednisolone and dexamethasone in HeLa cells.

Glucocorticoids regulate the levels of their cognate receptors in a number of target tissues and in many different cell lines. We have compared the effect of three glucocorticoids, cortisol and its synthetic derivatives, prednisolone an dexamethasone, on the levels of glucocorticoid receptor (GR) mRNA in HeLa cells. Clinically, the synthetic derivatives are more active in hormonal action and have a longer half-life than cortisol. In the present study, the amounts of GR mRNA in HeLa cells were examined by Northern blot hybridization after treatment with cortisol, prednisolone or dexamethasone. These glucocorticoids decreased GR mRNA levels differently. After 24 h treatment with 1 x 10(-5) M cortisol, GR mRNA levels were only marginally suppressed (90% of the control), while prednisolone and dexamethasone suppressed GR mRNA levels to 67 and 57%, respectively. These differences may relate to the biological activities of these glucocorticoids. In time course studies, GR mRNA levels of the cells treated with cortisol and prednisolone decreased to the minimum levels within 4 h and then recovered gradually, while those treated with dexamethasone reached the minimum level at 8 h and remained suppressed for more than 24 h. These differences may relate to the biological half-lives of these glucocorticoids.

Anti-Inflammatory Agents↗
PubMed1995

Effects of cervical spinal cord stimulation on glucose consumption in patients with posttraumatic prolonged unconsciousness.

The effects of cervical spinal cord stimulation (CSCS) on glucose consumption were examined in two patients with prolonged disturbance of consciousness due to head injuries. Several clinical parameters, including glucose consumption using positron emission tomography (PET) with [18F]2-fluoro-2-deoxy-D-glucose (FDG), were compared before and after CSCS. After a 4-month period of stimulation, one patient (Case 1) regained consciousness and began to speak, but the other patient (Case 2) showed no improvement in consciousness level. Computed tomography and magnetic resonance imaging showed Case 1 had no abnormalities in the thalamus and brainstem and no diffuse brain atrophy. Case 2 had a low density area in the left thalamus and enlargement of the aqueduct with diffuse atrophy of the left cerebral hemisphere. Cerebral blood flow studies and electrophysiological examinations revealed no remarkable change after CSCS. The PET study showed an increase in FDG uptake in the hypothalamus and the thalamus in both patients, but an increase in FDG uptake in the left cingulate gyrus and left frontal lobe was observed only in Case 1. These observations suggest that activation of the ascending reticular activating system, hypothalamus, thalamus, cingulate gyrus, and frontal cortex, and the preservation of the fiber connections between the limbic system and the thalamus and hypothalamus are important for CSCS treatment to improve the level of consciousness.

Adolescent↗
PubMed1995

Relation of family history of cancer and environmental factors to the risk of colorectal cancer: a case-control study.

The relation of a family history of cancer and environmental factors to colorectal cancer was investigated in a case-control study conducted from 1992 to 1994 at 10 medical institutions in Japan using a self-administered questionnaire, and 363 cases of colorectal cancer were compared with 363 controls matched for sex and age. A family history of colorectal cancer was positively associated with colon cancer (odds ratio (OR) = 2.0, 95% confidence interval (CI) 1.03-3.87) and rectal cancer (OR = 2.1 CI 0.94-4.48), but a family history of other cancers did not increase the risk. The proportion of patients with a family history of colorectal cancer within first-degree relatives was 12.4%--appreciably higher than figures previously reported in Japan. On the other hand, the incidence of hereditary non-polyposis colorectal cancer was 1.4%, and lower than previous estimates. Among dietary factors, a western-style diet significantly increased the risk of both colon and and rectal cancer (OR = 2.3 CI 1.30-3.88 and OR = 2.1 CI 1.26-3.63, respectively). Consumption of rice was protective against both colon and rectal cancer (OR = 0.5 CI 0.31-0.82 and OR = 0.3 CI 18-0.65, respectively). Animal meat, oily food, fish, vegetables and fruit were shown to affect the risk, but no statistically significant correlation was found. Among other factors, constipation increased the risk of colon cancer (OR = 2.0 CI 1.02-3.76) and consumption of coffee raised the risk of rectal cancer (OR = 1.7 CI 1.07-2.82). Our findings suggest that a family history of colorectal cancer is an important risk factor for this disease, and does not contradict the hypothesis that the risk of colorectal cancer in Japan may be influenced by westernization of lifestyle. However, we were unable to find conclusive evidence that familial clustering of this disease is strongly affected by environmental factors or genetic diseases such as hereditary non-polyposis colorectal cancer.

Adenocarcinoma↗
PubMed1995

[Squamous cell carcinoma of the lung with high CT number, but without calcification].

Squamous cell carcinoma of the lung was diagnosed in a 64-year-old man. Chest roentgenographic and tomographic examinations did not show areas of high-density in the tumor, but chest CT scan showed diffuse, scattered, high-density nodules in the tumor. Histologic examination did not show calcification, and calcium staining (Kossa method) was negative. Examination of the thin-slice CT, the soft X-ray film, and the resected slice of the lung indicated that the high-density nodules seen in the tumor on the chest CT scan corresponded to markedly fibrotic lesions with severe anthracosis. This case shows that high-density areas on a CT scan may reflect non-calcified lesions.

Calcinosis↗
PubMed1995

[Pulmonary malignant lymphoma associated with bilateral diffuse linear, reticular, and consolidated shadows].

A 72-year-old asymptomatic man was admitted to our hospital with abnormal chest radiographic findings: bilateral diffuse linear, reticular, and consolidated shadows. Malignant lymphoma (diffuse small-cell B-cell lymphoma) was diagnosed histologically after an open lung biopsy and was confirmed by a genetic examination. The lymphoma cells had infiltrated widely in various regions of the lung, including the alveolar spaces and walls, the bronchial and vascular spaces, and the pleura. This diffusion of the lymphoma cells might have accounted for the chest X-ray findings. Malignant pulmonary lymphoma should be included in the differential diagnosis patients with diffuse linear, reticular, and consolidated shadows on chest X-ray films.

Aged↗
PubMed1995

Clinicopathological study of dialysis patients with lupus nephritis.

To determine the clinical characteristics and long-term prognosis of 11 Japanese systemic lupus erythematosus (SLE) patients who were starting dialysis, we studied the clinicopathological findings before dialysis and during the clinical course after dialysis. Patients were divided into three groups: Group A consisting of temporary dialysis patients (n = 5); Group B consisting of early-death patient (n = 1); and Group C consisting of maintenance dialysis patients (n = 6). At the start of dialysis, the progression pattern of renal failure in all Group A patients was either acute exacerbation of chronic renal failure (CRF) or rapidly progressive glomerulonephritis (RPGN). The pattern in Group C was mostly CRF (83%). Three patients from Group A and three from Group C were still alive at the latest follow-up (mean follow-up period was 11.0 years, ranging from 1.8 to 16.2 years) and they showed no signs of clinical or serological activity. Infection was the cause of death in 3 of the 5 patients who died. We suggest that dialysis can be discontinued in patients with SLE who receive dialysis for acute exacerbation of CRF or RPGN. After the initiation of dialysis, patients tend to show diminished SLE activity. Infection is the major contributor to the poor prognosis of SLE patients receiving dialysis.

Adult↗
PubMed1995

Chronic hyperinsulinaemia and hypertension: the role of the sympathetic nervous system.

OBJECTIVE: To determine the implication of the sympathetic nervous system in the relationship observed between insulin resistance and hypertension. DESIGN: Rats were chronically treated with insulin for 12 days by subcutaneously implanted osmotic pumps and given 10% glucose in their drinking water. A separate group of rats also received glucose only, and control rats received tap water. RESULTS: Physiological hyperinsulinaemia (1.5 and 4.5 mU/kg per min insulin) increased mean arterial pressure by approximately 10 mmHg and heart rate by 60 beats/min, and supraphysiological insulinaemia (9 mU/kg per min) did not produce additional haemodynamic effects. Insulin-treated rats developed insulin resistance, as shown by an intravenous glucose-tolerance test. Glucose treatment alone induced intermediate haemodynamic and metabolic responses. Plasma noradrenaline levels rose slightly in insulin-treated rats and were positively correlated with mean arterial pressure but not with insulinaemia, even though insulinaemia was also correlated with mean arterial pressure. The reflex sympathetic activation during hypotension revealed, in the presence of a noradrenaline uptake antagonist, that insulin increases noradrenaline release but also enhances noradrenaline uptake. Chronic hyperinsulinaemia did not alter the sympathetic vascular and cardiac responses, as assessed by the measurement of the second messengers produced by activation of alpha 1- or beta-adrenergic receptor pathways. CONCLUSION: Chronic euglycaemic hyperinsulinaemia seems to modify sympathetic activity through several mechanisms, and this action could participate in the elevation of blood pressure observed in this rat model.

Animals↗
PubMed1995

[A case of renal vein thrombosis and pulmonary embolism associated with diffuse membranous glomerulonephritis: the usefulness of low-molecular-weight heparin and urokinase therapy].

We report a case of renal vein thrombosis (RVT) and pulmonary embolism associated with diffuse membranous glomerulonephritis. A 44-year-old Japanese male was referred to the Nephrology Department with heavy proteinuria. Renal biopsy revealed diffuse membranous glomerulonephritis and we administered PSL 30mg/day and dipyridamole 300mg/day. Three weeks later, he was admitted with severe chest pain, dyspnea and massive proteinuria. RVT and pulmonary embolism were detected on CT scan and perfusion lung scan. After a few days of continuous intravenous unfractionated heparin (UFH) therapy, we used 72 U (anti-FXa)/kg of intravenous low-molecular-weight heparin (LMWH) every 12 hours for 10 days. He also received urokinase at the dose of 120,000 U/day for 4 weeks and long-term therapy with warfarin potassium at the dose of 3 mg/day. One month later, the thrombi in the pulmonary arteries and inferior vena cava disappeared on CT scan and perfusion lung scan. LMWHs have a longer biological half-life and a lower bleeding tendency than UFH for an equivalent antithrombotic effect. This case indicates that intermittent intravenous LMWH administration combined with urokinase is effective against RVT and pulmonary embolism without any side effect.

Adult↗
PubMed1995

[Hematologic improvement by alpha-interferon in a case of the 5q- syndrome with basophilia and eosinophilia].

An 82-year-old female was diagnosed as having 5q- syndrome accompanied by basophilia, eosinophilia and thrombocytosis. Since cytogenetic abnormalities other than 5q- were also detected, she was considered to be type B of 5q- syndrome. According to the FAB classification a diagnosis of refractory anemia with excess of blasts (RAEB) was made. She was treated with recombinant interferon alpha 2b, because peripheral blood findings resembled those of chronic myelogenous leukemia. Interferon was effective, and resulted in disappearance of peripheral blasts, normalization of platelet numbers, and improvement of basophilia. These changes were interferon-dependent. After 1 year, cytogenetic studies revealed that about 2/3 of metaphases showed normal karyotype. Twenty months after diagnosis, myeloid blastic crisis occurred and eventually the patient died. However, treatment with interferon in this case might support the usefulness of the drugs for this kind of disease.

Aged↗
PubMed1995

Enhancement of growth of rabbit corneal endothelial cells by PDGF.

The effect of platelet-derived growth factor (PDGF) on the growth of rabbit corneal endothelial cells and the expression of PDGF receptor mRNA in these cells were examined in the present study. When rabbit corneal endothelial cells were cultured in the presence of natural PDGF, recombinant PDGF-BB, and PDGF-AA for 1, 3, and 5 days, natural PDGF and recombinant PDGF-BB enhanced the growth of the endothelial cells, but PDGF-AA did not. This growth promotion was suppressed by anti-PDGF antibody. PDGF enhanced also the incorporation of 3H-thymidine into the cells. When PDGF was combined with epidermal growth factor (EGF), the additive effect was recognized. The expression of the PDGF receptor mRNA was found in the endothelial cells by the polymerase chain reaction (PCR) method. It was concluded from these results that PDGF enhanced the growth of the corneal endothelial cells and that the PDGF receptor mRNA was expressed in these cells. These results suggest that PDGF may regulate corneal endothelial cell growth.

Animals↗
PubMed1995

[Clinical significance of lymphadenopathy in the upper abdomen; ultrasound demonstration].

Little attention has been paid to the ultrasound differentiation of benign abdominal lymphadenopathy from the malignant type. We reviewed 133 ultrasound examinations of 116 patients with lymphadenopathy seen over the upper abdomen and high retroperitoneum to clarify the differences in ultrasound findings of enlarged lymph nodes caused by benign and malignant abdominal diseases. The location, number, internal texture, size, length/thickness ratio of the lymph nodes, and relation with hepatitis virus infection were evaluated. Among 75 patients with benign diseases, 63 patients showed liver dysfunction and 42/65 (65%) showed positive hepatitis C virus antibody (HCV-Ab). Enlarged lymph nodes were seen over the common hepatic artery or hepatoduodenal ligament in 84%. Most patients had fewer than 4 enlarged nodes, and 46 patients had a single enlarged node. The length/thickness ratio of nodules was more than 2.5 in 63%. In 41 patients with malignant diseases, enlarged lymph nodes tended to be more widespread in location, larger in number, and smaller in length/thickness ratio than those of benign diseases. Lymphadenopathy over the common hepatic artery or hepatoduodenal ligament may suggest the presence of chronic active hepatitis, especially relating to HCV infection, even though hepatic sonotexture is normal on ultrasound examination.

Abdomen↗
PubMed1995

Protection of myocardial tissue against deleterious effects of oxygen free radicals by ceruloplasmin.

This study describes the carioprotective effect of ceruloplasmin (CAS 9031-37-2) against oxygen free radical injury, as indicated by several biochemical indicators and some cardiodynamic variables. Isolated rat hearts (n = 4-8, p < 0.05, for each experimental point) in Langendorff preparation were exposed to oxygen free radicals generated by electrolysis (10 mA) in the absence and the presence of 0.25 mumol/l purified ceruloplasmin and denaturated ceruloplasmin, in Krebs-Henseleit perfusion solutions. Biochemical indicators (noradrenaline, malondialdehyde, creatine-kinase, lactate dehydrogenase, aspartate aminotransferase, Ca2+ and Mg2+) as well as the electrocardiogram and the left ventricular pressure (LVP), were altered by oxygen free radicals formation, denoting major cellular and tissular damages in the nontreated hearts. Ceruloplasmin exhibited a cardioprotective effect and prevented the oxygen free radical-induced release of noradrenaline, indicating that it can also protect the sympathetic nerve endings from oxygen free-radical injury. Purified ceruloplasmin, a circulating extracellular antioxidant and oxygen free radical scavenger, seems to be an effective heart protective agent against myocardial and neuronal injuries generated by oxygen free radicals.

Animals↗
PubMed1995

[Arterial oxygen saturation monitoring of sleeping infants by pulse-oximeter--effect of sleeping position on arterial oxygen saturation in infants].

Monitoring of the arterial oxygen saturation (SaO2) in two sleeping infants was reported. They were a couple of female twins and had grown up normally after admission to NICU (Neonatal Intensive Care Unit) for a month. We investigated their SaO2 with the puls-oximeter at the terms between the 2nd and the 10th month. There was no significant difference between SaO2 in prone positions (n = 29) and that in supine positions (n = 30). In the infant with the sniffing conditions, however, SaO2 in prone positions seemed to be slightly lower than that in the healthy conditions. The slightly low SaO2 would give no effects on the healthy infants, but it may cause ALTE (Apparent Life Threatening Event) or death from SIDS (Sudden Infant Death Syndrome) to some infants who are not in good health and/or who are prone to get into ALTEA or SIDS. Especially, in the sniffing condition with hyperthermia, as the oxygen dissociation curve sifts to right and SaO2 degradation appears easily, sudden infant death may be possible to happen in prone position.

Blood Gas Analysis↗
PubMed1995

A possible involvement of sodium channel blockade of class-I-type antiarrhythmic agents in postischemic contractile recovery of isolated, perfused hearts.

The present study was undertaken to test the hypothesis that the degree of sodium channel blockade by class-I-type antiarrhythmic agents accounts for enhancement of postischemic contractile recovery of ischemic/reperfused hearts. Electrophysiological studies showed that the class-I-type antiarrhythmic agents quinidine, disopyramide, procainamide, lidocaine, mexiletine, flecainide and pilsicainide suppressed the Vmax value of the rat left ventricular muscle cell, a marker of sodium channel blockade, in a concentration-dependent manner. Isolated rat hearts were subjected to 35 min of ischemia and 60 min of reperfusion. Postischemic contractile recovery, which was never detected in untreated hearts, was enhanced in hearts pretreated with these antiarrhythmic agents during the last 3 min before ischemia at concentrations ranging from 3 to 300 microM. Tissue Na, but not Ca, accumulation was also detected in the ischemic heart, and tissue Na and Ca accumulation was observed in the reperfused heart, which suggests that sodium overload occurs during ischemia, followed by sodium and calcium overload during reperfusion. The degree of postischemic contractile recovery seen in the presence of these antiarrhythmic agents was inversely related to tissue Na or Ca accumulation after reperfusion, which suggests that class-I-type antiarrhythmic agents inhibit sodium overload occurring in ischemic/reperfused myocardial cells. A close relationship between postischemic contractile recovery of the perfused heart and depression in the Vmax value of the ventricular muscle was also observed. These results suggest that the ability class-I-type antiarrhythmic agents to inhibit myocardial sodium channels plays a significant role in the enhancement of postischemic contractile recovery of the ischemic/reperfused heart.

Animals↗
PubMed1995

[Philadelphia chromosome-negative chronic myelogenous leukemia with trisomy 13].

Trisomy 13, as a sole karyotypic abnormality in acute leukemia, has been reported in several cases. However, in chronic myelogenous leukemia (CML), only two cases with this abnormality were reported so far. We describe herein a 68-year-old case with Philadelphia chromosome-negative CML and trisomy 13. Leukocytosis was pointed out during the treatment for other diseases. After 7 months, abrupt increase in leukocyte count (108,000/microliters) and splenomegaly developed. Decreased neutrophil alkaline phosphatase activity and morphological features fulfilled the diagnostic terms for CML. However, the karyotypic analysis revealed trisomy 13 instead of Philadelphia chromosome, and the BCR gene rearrangement was not detected. In cases with acute leukemia accompanied by trisomy 13, malignant transformation of an immature hematopoietic precursor cell has been suggested by the expression of antigens characteristic of both the myeloid and lymphoid lineage. In a few cases with myelodysplastic syndrome, a multipotent stem cell disorder, trisomy 13 has also been reported. From these standpoints, there might be a possibility that trisomy 13 as a sole abnormality in hematologic disorders would be related to tumorigenesis in the levels of multipotent stem cells.

Aged↗