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Biomedical subjects

T Sadamoto

Publications and source records attributed to T Sadamoto.

At least 19 recordsLinked to original sources
PubMed2001

Ductular morphogenesis and functional polarization of normal human biliary epithelial cells in three-dimensional culture.

BACKGROUND/AIMS: The understanding of the physiology and function of human biliary epithelial cells (hBEC) has been improved by studies in monolayer culture systems. The aim was to develop a polarized model to elucidate the mechanisms of ductular morphogenesis and functional differentiation of hBEC. METHODS: The morphological, phenotypic and functional properties of hBEC cultured as three-dimensional aggregates in collagen gel were assessed in medium supplemented with (or without) human hepatocyte growth factor (hHGF) and foetal bovine serum. RESULTS: In the absence of added mitogens and serum, cells maintained as morphologically polarized aggregates, organized around a central lumen, were positive for phenotypic markers of biliary epithelium and negative for markers of other cell types. Functional markers, gamma-glutamyl-transferase, anion exchanger-2, responses to gamma interferon and forskolin induced secretion, were preserved. hHGF increased both the size and number of aggregates and induced hBEC to invade the gel and lumena forming anastomosing networks of cells. CONCLUSIONS: Collagen gel culture in the absence of added growth factors and serum provides a model for analysis of the polarized functions of hBEC. The formation of poorly organized cords of cells in response to hHGF suggests that collagen gel culture may provide a model for the investigation of atypical ductular morphogenesis of the human biliary tract.

Adult↗
PubMed2001

Reflex responses in plasma catecholamines caused by static contraction of skeletal muscle.

To examine a hypothesis of whether static muscle contraction produces a release of catecholamines from the adrenal medulla via reflex stimulation of preganglionic adrenal sympathetic nerve activity induced by receptors in the contracting muscle, we compared the reflex responses in a concentration of epinephrine (Ep) and norepinephrine (NEp) in arterial plasma during static contraction and during a mechanical stretch of the hindlimb triceps surae muscle in anesthetized cats. Static contraction was evoked by electrically stimulating the peripheral ends of the cut L(7) and S(1) ventral roots at 20 or 40 Hz. Mean arterial pressure (MAP) and heart rate (HR) increased 23 +/- 3.1 mmHg and 19 +/- 4.3 beats/min during static contraction. Ep in arterial plasma increased 0.18 +/- 0.072 ng/ml over the control of 0.14 +/- 0.051 ng/ml within 1 min from the onset of static contraction, and NEp increased 0.47 +/- 0.087 ng/ml over the control of 0.71 +/- 0.108 ng/ml. Following a neuromuscular blockade, although the same ventral root stimulation failed to produce the cardiovascular and plasma catecholamine responses, the mechanical stretch of the muscle increased MAP, HR, and plasma Ep, but not plasma NEp. With bilateral adrenalectomy, the baseline Ep became negligible (0.012 +/- 0.001 ng/ml) and the baseline NEp was lowered to 0.52 +/- 0.109 ng/ml. Neither static contraction nor mechanical stretch produced significant responses in plasma Ep and NEp following the adrenalectomy. These results suggest that static muscle contraction augments preganglionic adrenal sympathetic nerve activity, which in turn secretes epinephrine from the adrenal medulla into plasma. A muscle mechanoreflex from the contracting muscle may play a role in stimulation of the adrenal sympathetic nerve activity.

Adrenal Medulla↗
PubMed2000

Attenuated cardiovascular adjustment to sustained static exercise after carbohydrate loading.

We examined whether a higher plasma lactic acid (LA) concentration resulting from carbohydrate (CHO)-loading affects the cardiovascular responses to exercise through a greater activation of LA-induced metaboreflex. Before and after CHO-loading, LA concentration, mean arterial blood pressure (MAP), heart rate (HR), cardiac output (CO), rating perceived exertion (RPE), and integrated electromyogram (iEMG) of the vastus lateralis were studied during a sustained static knee extension of single legs in 16 volunteers. The CHO-loading comprised an exhaustive bout of one-legged cycling (73+/-3% of maximal oxygen uptake for 130-160 min) and consuming a low-CHO diet for 2-3 days and a high-CHO diet for the next 3 days. In the leg that performed the exercise (the experimental leg), the LA concentration after CHO-loading was significantly increased, but the magnitude of MAP, HR, and CO responses during static exercise was significantly decreased in parallel with a significant reduction of RPE and iEMG. In the control leg, there were no changes in the variables before and after CHO-loading. These results suggest that the increased LA concentration resulting from CHO-loading did not affect the cardiovascular adjustment to the sustained exercise. Other mechanisms related to the reduction of RPE and iEMG seem to be responsible for the attenuated cardiovascular responses observed in the experimental leg after CHO-loading.

Adult↗
PubMed1999

Molecular epidemiological study of a mass outbreak caused by enteropathogenic Escherichia coli O157:H45.

We made a molecular analysis of O157:H45 Escherichia coli isolated from a mass outbreak that occurred in Obihiro City. Using DNA analysis, we confirmed this infection case as a mass outbreak. Although the isolates expressed O157 antigen, they did not produce Vero toxin. We concluded they were enteropathogenic E. coli (EPEC) because they had a bfp gene and an EAF plasmid, and further they exhibited local adherence to HEp-2 cells. We believe this is the first report of a mass outbreak by O157 EPEC, and we suggest that PCR using eae- and bfp-specific primers and HEp-2 adherence assay are useful to identify EPEC.

Disease Outbreaks↗
PubMed1997

Cardiovascular responses during spontaneous overground locomotion in freely moving decerebrate cats.

To examine whether the cerebrum is essential for producing the rapid cardiovascular adjustment at the beginning of overground locomotion, we examined heart rate (HR), mean arterial blood pressure (MAP), and integrated electromyogram (iEMG) of the forelimb triceps brachialis muscle in freely moving decerebrate cats during locomotion. Two to four days after decerebration surgery performed at the level of the precollicular-premammillary body, the animals spontaneously produced coordinated overground locomotion, supporting body weight. HR began to increase immediately before the onset of iEMG, and MAP began to rise almost simultaneously with the iEMG onset. Their increases in HR and MAP (24 +/- 3 beats/min and 22 +/- 4 mmHg) were sustained during locomotion. Sinoaortic denervation (SAD) did not affect the abrupt changes in HR and MAP at the beginning of locomotion (0-4 s from the onset of iEMG), whereas SAD had a contrasting effect during the subsequent period, a decrease in the HR response (9 +/- 1 beats/min) and an increase in the MAP response (30 +/- 3 mmHg). These results suggest that the cerebrum and the rostral part of the diencephalon are not essential for producing the rapid cardiovascular adjustment at the beginning of spontaneous overground locomotion. The arterial baroreflex does not contribute to this rapid adjustment but plays an important role in regulating the cardiovascular responses during the later period of spontaneous locomotion.

Animals↗
PubMed1997

Enzyme immunoassay of glioma cell tenascin secretion and augmentation by tumor necrosis factor-alpha.

Expression of tenascin, an extracellular matrix glycoprotein, was measured in glioma cell lines using a newly established enzyme immunoassay. Secreted tenascin was found at concentrations greater than 800 ng/ml in eight of 14 glioma, three small cell lung carcinoma, two melanoma, and one sarcoma cell lines. The remaining six glioma and other carcinoma cell lines, and cell lines originating from normal tissues demonstrated low levels or no secretion into the supernatant. The glioma cell line, U-251-MG nu/nu, which has almost 100% transplantability in nude mice, had the highest expression level of tenascin among the glioma cell lines examined. Even low secretor glioma cell lines released high concentrations of tenascin, detectable by assaying the NP-40 solubilized cell lysates. Flow cytometric analysis revealed that tenascin was located on both the cell surface and primarily in the cytoplasm of glioma cells. When the glioma cell lines were exposed to tumor necrosis factor-alpha (TNF-alpha), levels of secreted tenascin increased between 36% and 380%, whereas transforming growth factor-beta induced only minimal changes. These results suggest that glioma cell lines may be classified according to the degree of tenascin secretion/expression: high secretor type, low secretor type, and non-expressing type. The increase in tenascin secretion by TNF-alpha suggests that the expression of tenascin in glioma growth and development may be mediated through a cytokine network.

Animals↗
PubMed1994

Clinicopathological study of proliferating cell nuclear antigen (PCNA) of hepatocytes in primary biliary cirrhosis.

The DNA synthesis activities of hepatocytes in primary biliary cirrhosis (PBC) and other chronic liver diseases and control subjects were examined by staining proliferating cell nuclear antigen (PCNA) with anti-PCNA monoclonal antibody. The number of PCNA-positive cells (PCNA value) was significantly higher in PBC (375 +/- 281 parts per thousand; ppt) than in other chronic liver diseases, i.e., chronic hepatitis (95 +/- 83 ppt), liver cirrhosis (72 +/- 71 ppt), and alcoholic liver disease (73 +/- 56 ppt), and in control subjects (11 +/- 14 ppt). The PCNA value of PBC in stages I-III of Scheuer's classification was remarkably high, while in stage IV it was low. Even in identical, Scheuer's stages, the PCNA value of PBC was higher in patients who were not given ursodeoxycholic acid (UDCA) than in those who received UDCA. In identical patients, the PCNA value was lowered significantly after UDCA treatment. It was concluded that the DNA synthesis activity of PBC in stages I-III was accelerated and that UDCA can alleviate the abnormality in DNA synthesis activity.

Chronic Disease↗
PubMed1993

Glucose ingestion before and during exercise does not enhance performance of daily repeated endurance exercise.

The effect of glucose (Glc) ingestion before and during daily, repeated, prolonged exercise on metabolism and performance was tested. Seven young, healthy males performed cycling exercise in two series, with 1 month interval. Each exercise series consisted of 1 h/day on 3 successive days. On the 3rd day, exercise was continued until exhaustion. The intensity was 73.4 (7.7)% [mean (SD)] of maximal oxygen uptake (VO2max). Glucose (Glc) or placebo (P) drink was ingested 15 min before the start, and at 15 and 45 min of each daily exercise. The total amount of Glc ingested was 43.1 (4.2) g. During exercise, blood Glc concentrations were significantly higher (P < 0.05) when Glc was ingested than when P was ingested [Glc 5.14 (0.32) and P 4.12 (4.17) mmol.l-1 at exhaustion]. However, Glc ingestion did not improve performance time to exhaustion [Glc 92.05 (29.55) and P 98.07 (27.33) min]. Free fatty acid concentrations were significantly lower when Glc was ingested than when P was ingested [Glc 0.63 (0.21) and P 1.39 (0.46) mmol.l-1 at exhaustion]. There were no significant differences in exercise heart rate, VO2, respiratory exchange ratio, blood lactate concentrations or rating of perceived exertion between the conditions nor were there any significant differences in these parameters on different days of exercise. It seems that ingestion of small amounts of Glc does not increase the metabolism of carbohydrate or improve the performance of intensive endurance exercise of poorly trained subjects, even when the exercise is repeated daily.

Adult↗
PubMed1992

Accumulation of allelic loss on arms of chromosomes 13q, 16q and 17p in the advanced stages of human hepatocellular carcinoma.

We examined loss of heterozygosity at 13 loci on 5 chromosomes in hepatocellular carcinomas (HCCs) from 56 patients. In 42 of these cases, regenerative nodules of liver cirrhosis were also analyzed. High frequencies of allelic losses were detected on chromosomes 13q (47%), 16q (40%) and 17p (64%), whereas losses on chromosome 4p and 11p were observed in less than 22% of cases in HCCs. In contrast, LOH was not detected on any loci in cirrhotic nodules. On chromosome 13q, the common region of allelic loss was mapped to the region including the retinoblastoma (RB) locus, by using 8 polymorphic probes. Furthermore, one case with 13q loss had an interstitial deletion of the RB gene, indicating the involvement of inactivation of the RB gene in hepatotumorigenesis. Losses were associated with portal-vein thrombosis or intrahepatic metastasis, increased tumor size, a poorly differentiated phenotype and clinical stage. Losses occurring together on 13q, 16q and 17p were significantly higher in patients in clinical stage IV or histologically poorly differentiated tumors, suggesting that the accumulation of allelic loss occurs in advanced tumors and that patients with multiple allelic losses may have a worse prognosis than those with a single loss.

Alleles↗
PubMed1992

Cardiovascular reflexes during sustained handgrip exercise: role of muscle fibre composition, potassium and lactate.

Six healthy men performed sustained static handgrip exercise for 2 min at 40% maximal voluntary contraction followed by a 6-min recovery period. Heart rate (fc), arterial blood pressures, and forearm blood flow were measured during rest, exercise, and recovery. Potassium ([K+]) and lactate concentrations in blood from a deep forearm vein were analysed at rest and during recovery. Mean arterial pressure (MAP) and fc declined immediately after exercise and had returned to control levels about 2 min into recovery. The time course of the changes in MAP observed during recovery closely paralleled the changes in [K+] (r = 0.800, P < 0.01), whereas the lactate concentration remained elevated throughout the recovery period. The close relationship between MAP and [K+] was also confirmed by experiments in which a 3-min arterial occlusion period was applied during recovery to the exercised arm by an upper arm cuff. The arterial occlusion affected MAP while fc recovered at almost the same rate as in the control experiment. Muscle biopsies were taken from the brachioradialis muscle and analysed for fibre composition and capillary supply. The MAP at the end of static contraction and the [K+] appearing in the effluent blood immediately after contraction were positively correlated to the relative content of fast twitch (% FT) fibres (r = 0.886 for MAP vs % FT fibres, P < 0.05 and r = 0.878 for [K+] vs % FT fibres, P < 0.05). Capillary to fibre ratio showed an inverse correlation to % FT fibres (r = -0.979, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Insulinopenia as a risk factor in hepatectomy and its resolution by intraportal insulin administration.

Insulopenia is a possible risk factor in hepatectomy, especially since insulin has been recognized to have a significant hepatotrophic effect. In the current study, insulinopenic patients were defined as those who showed abnormally low insulinogenic indexes (less than 0.6) on the oral glucose tolerance test, compared with those in 22 normal volunteers (1.16 +/- 0.57, mean +/- SD). The insulinogenic index represents the ratio of the cumulative enhancement of immunoreactive insulin (IRI) to the glucose level (delta IRI/delta glucose). Surgical outcomes were studied retrospectively in 17 insulinopenic patients who underwent hepatic resections from January 1987 to July 1988. Six of 10 patients in the major hepatic resection group showed postoperative complications, 5 of whom experienced hepatic failure resulting in hospital death. By contrast, all seven patients in the minor resection group tolerated the operations. From August 1988, intraportal insulin was prospectively administered as a posthepatectomy management technique to nine patients, eight of whom were diagnosed as insulinopenic. These patients all tolerated major hepatic resections including four hepatic vascular exclusion procedures with veno-venous bypass. In conclusion, the current study indicates that insulinopenic patients are high-risk candidates for major hepatic resection and that intraportal insulin administration has a beneficial effect on the postoperative management of these patients.

3-Hydroxybutyric Acid↗
PubMed1991

O6-methylguanine-DNA methyltransferase activity in human liver tumors.

Previous studies have shown that in about one-fifth of human tumor cell strains, the activity of O6-methylguanine-DNA methyltransferase (MGMT), which can repair O6-alkylguanine in DNA produced by alkylating agents, is deficient. These strains are termed Mer- cells. To see if there is any human tumor lacking MGMT activity, we measured the MGMT activity in extracts from liver tumors of 21 patients, and compared it to the activity in normal peritumoral tissues derived from the same patients. The MGMT activity was assayed by measuring the 3H radioactivity transferred from the substrate DNA containing [methyl-3H]-labeled O6-methylguanine to an acid-insoluble protein fraction. There was considerable variation in MGMT activity among individual extracts; the interindividual variation was approximately 6-fold in normal liver tissue and much larger in liver tumors. Although in many cases similar high levels of MGMT activity were found both in liver tumors and in the normal counterpart, six tumors had greater than 3-fold less activity compared with the normal liver tissue from the same patient. Liver tumors from two patients did not have any detectable level of MGMT activity by the present method used, in spite of the fact that the corresponding normal liver samples demonstrated significant activities. We also measured in the same tissue extracts the activities of two common enzymes, glutamic pyruvic transaminase (GPT) and lactic dehydrogenase (LDH). The activities of GPT and LDH in the liver tumor samples that showed undetectable levels of MGMT activity were similar to those in the surrounding normal liver tissues. These results may suggest the existence of human Mer- tumors, deficient or very low MGMT activity.

Aged↗
PubMed1991

[Positive rate of serum anti-HCV in various liver diseases and the clinico-pathological study of chronic liver disease in alcoholics].

The aim of this study was to elucidate the positive rate of serum anti-HCV in alcoholic (with negative HBsAg and without blood transfusion history) and non-alcoholic (type-B and type-NANB) patients with chronic liver diseases. The clinico-pathological difference between anti-HCV positive and negative alcoholic patients was also investigated. Anti-HCV (Chiron C-100-3) was assayed with Ortho EIA kit in 196 patients. Liver function tests and the histological findings were evaluated in 111 cases of chronic hepatitis (CH) and 39 of liver cirrhosis (LC). Following results were obtained. [1] Positive rate of serum anti-HCV in alcoholic patients was 40% in CH, 36% in LC and 100% in hepatocellular carcinoma. In non-alcoholic type-NANB group, it was 75%, 68% and 69%, respectively. [2] Serum GGT/ALT ratio was higher in anti-HCV negative patients than positive patients both in CH and LC alcoholics. In non-alcoholic group, it was higher in type-NANB patients than type-B patients. [3] Among the histological findings in CH alcoholics, lymph follicles in the portal area were characteristic in anti-HCV positive patients, while these were not seen in negative patients. [4] In LC alcoholics, regenerative nodules were irregular in size in anti-HCV positive patients, while these were even and small in negative patients. [5] Serum HCV-RNA was detected in two out of 14 anti-HCV negative patients. [6] A female alcoholic patient who showed positive serum anti-HCV and negative HCV-RNA was presented. [7] For the evaluation of the influence of HCV in alcoholics, further studies have to be continued with more sensitive HCV markers.

Adult↗
PubMed1991

[Influence of hepatitis C virus on the alcoholic liver diseases].

In order to know the influence of hepatitis C virus (HCV) on the alcoholic liver diseases (ALD), 124 patients with ALD were divided into two groups by positive or negative anti-HCV, and differences of histological findings, laboratory data, evolution of histopathology and liver disease of those who developed hepatocellular carcinoma (HCC) between both groups were investigated. There were 31 patients (25%) in the anti-HCV positive group and 93 patients (75%) in the negative group. Histologically, viral changes were seen in most patients (55%) of the positive group, whereas those were seen in a few patients (15%) of the negative group. The patients of the positive group showed higher serum adenosine deaminase levels compared with those of the negative group. However, as regards the evolution of histopathology, amount of alcohol consumed seemed to be more responsible than positive anti-HCV. Three out of 6 patients with HCC were anti-HCV positive cirrhotics, although there were three anti-HCV negative HCC patients: one with cirrhosis and two with hepatic fibrosis.

Adenosine Deaminase↗
PubMed1991

[Studies on the mode of progression of alcoholic liver disease].

In order to elucidate the mode of progression of alcoholic liver disease, relationships among the drinking style, laboratory data, anti-HCV antibody and histological changes were investigated on 36 patients in whom the liver biopsy was repeatedly done. Following results were obtained (1) In the group of continuous drinking over 100g ethanol per day, histological progression was found in 11 of 13 patients (85%) regardless of positive anti-HCV. On the other hand, in the group of abstinence or temperance less than 60g daily alcohol intake, histological improvement was found in 6 of 11 patients (55%). (2) Histological improvement was predominantly seen by abstinence or temperance in the cases with lower levels of serum IgA and adenosine deaminase (ADA) on hospitalization and those with rapid decrease in serum gamma-GTP after hospitalization. In conclusion, the amount of ethanol was considered to be the most important factor to affect on a progression of alcoholic liver diseases. Assessment of laboratory data such as IgA and ADA on hospitalization and change in gamma-GTP after hospitalization were also thought to be useful in foreseeing the prognosis of alcoholic liver disease.

Alcohol Drinking↗