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Biomedical subjects

T Ide

Publications and source records attributed to T Ide.

At least 127 records · Page 7Linked to original sources
PubMed1998

Telomerase activation by hTRT in human normal fibroblasts and hepatocellular carcinomas.

Telomerase is a specialized type of reverse transcriptase which catalyzes the synthesis and extension of telomeric DNA (for review, see ref.1). This enzyme is highly active in most cancer cells, but is inactive in most somatic cells. This striking observation led to the suggestion that telomerase might be important for the continued growth or progression of cancer cells. However, little is known about the molecular mechanism of telomerase activation in cancer cells. Human telomerase reverse transcriptase (hTRT) has recently been identified as a putative human telomerase catalytic subunit. We transfected the gene encoding hTRT into telomerase-negative human normal fibroblast cells and demonstrated that expression of wild-type hTRT induces telomerase activity, whereas hTRT mutants containing mutations in regions conserved among other reverse transcriptases did not. Hepatocellular carcinoma (20 samples) and non-cancerous liver tissues (19 samples) were examined for telomerase activity and expression of hTRT, the human telomerase RNA component (hTR; encoded by TERC) and the human telomerase-associated protein (hTLP1; encoded by TEP1). A significant correlation between hTRT expression and telomerase activity was observed. These results indicate that the hTRT protein is the catalytic subunit of human telomerase, and that it plays a key role in the activation of telomerase in cancer cells.

Amino Acid Sequence↗
PubMed1998

Minimum alveolar anesthetic concentrations for airway occlusion in cats: a new concept of minimum alveolar anesthetic concentration-airway occlusion response.

UNLABELLED: Minimum alveolar anesthetic concentration (MAC) is defined as an end-tidal concentration of inhaled anesthetic required to prevent purposeful movement (positive motor response) in 50% of subjects to somatic noxious stimuli. Although MAC for visceral noxious stimuli has not been well investigated, airway occlusion can be a noxious respiratory stimulus that can induce a visceral sensation of choking. In this study, MAC for airway occlusion (MAC-AOR) was determined during halothane, isoflurane, and sevoflurane anesthesia and compared with the MAC values for somatic noxious stimuli such as toe pinch (MAC-pinch) or tetanic stimulus (MAC-tetanus) in cats. Thirty-four adult cats were used. In 24 cats, the motor responses to three different stimuli (toe pinch, tetanic stimulus, and airway occlusion for 6 min) were observed during inhaled anesthesia and rated as positive or negative. The concentration of an inhaled anesthetic was changed in steps of 0.1%-0.2 vol% until the bracketing procedure (i.e., the highest concentration of inhaled anesthetic permitting a positive motor response and the lowest concentration preventing the response were determined) was completed. In 10 cats, the effect of anesthetic duration on MAC-AOR was also investigated. Each mean MAC (MAC-pinch, MAC-AOR, and MAC-tetanus, respectively) was as follows: halothane 0.99, 1.13, and 1.46; isoflurane 1.50, 1.65, and 2.22; and sevoflurane 3.07, 3.38, and 3.95. The first and last MAC-AOR values determined during 6-h halothane anesthesia were 1.10 and 1.11, respectively. In conclusion, airway occlusion can be a noxious stimulus and can induce an all-or-none type of motor response, depending on the depth of inhalational anesthesia in cats. This phenomenon can permit the introduction a new concept of MAC-AOR. IMPLICATIONS: Airway occlusion can be a noxious visceral stimulus and induce all-or-none type of motor response in cats, depending on the depth of inhalational anesthesia. This permits the introduction of a new concept of minimum alveolar anesthetic concentration airway occlusion response.

Airway Obstruction↗
PubMed1998

The inhibitory influence of pulmonary vagal afferents on respiratory distress induced by airway occlusion in halothane-anesthetized cats.

UNLABELLED: Although the sensation of dyspnea is common, the mechanisms underlying the sensation have not been fully elucidated. Dyspnea, which is a subjective sensation induced by various respiratory and nonrespiratory stimuli, ranges in intensity from an awareness of difficulty in breathing to an incapacitating state of respiratory distress. It need not be an all or none concept when tolerable; however, intolerable dyspnea is often accompanied by some kind of escape response. In a previous study, we developed a new concept of minimum alveolar anesthetic concentration for airway occlusion (MAC-AOR). Using this model, we assessed the influence of pulmonary vagal afferents on respiratory distress induced by airway occlusion. Adult cats (n = 13) of both sexes weighing 2.7-5.6 kg (3.9 +/- 0.3 kg, mean +/- SE) were anesthetized with halothane and tracheally intubated. After determination of MAC-AOR, anesthesia was maintained with the highest concentration of halothane permitting the positive motor response identified by visual inspection or electromyogram (EMG) of the forearm, usually of the head or extremities. Twisting or jerking of the head was considered a positive response, but twitching or grimacing was not. A slight movement of the shoulder and/or the extremities was not considered positive, nor were coughing, swallowing and chewing, or rigidity recognized as the increase of tonic activity on the forearm EMG. The duration from the start of airway occlusion to the onset of the positive response (DOCCL) was considered as behavioral measures of the tolerable limit of respiratory distress. DOCCL was measured before (Control 1), during, and after (Control 2) lung expansion induced by the injection of the inhaled gas of 5 mL/kg or 10 mL/kg (LE5 or LE10) at functional residual capacity level. Subsequently, 6 of 13 cats received bilateral vagotomies, and the same procedure was repeated at the same concentration as stated above. Then, MAC-AOR after vagotomy was determined again. Before vagotomy, the values of DOCCL during lung expansion (238 +/- 30 s during LE5 and 288 +/- 24 s during LE10) were significantly longer than Control 1 (169 +/- 29 s) and Control 2 (154 +/- 29 s) values (P < 0.01). After vagotomy, the effect of lung expansion on DOCCL was totally abolished. MAC-AOR after vagotomy (1.4% +/- 0.1%) was significantly higher than that before vagotomy (1.1% +/- 0.1%) (P < 0.01). We have demonstrated that vagotomy abolishes the prolongation effect of the lung expansion on DOCCL and increases the value of MAC-AOR in this animal model. These results suggest that pulmonary vagal afferents play an important role in relief of respiratory distress developed during airway occlusion. IMPLICATIONS: In anesthetized cats, we found that lung expansion reduces the tolerable limit to airway occlusion and vagotomy decreased minimum alveolar anesthetic concentration for airway occlusion, which suggests that pulmonary vagal afferents play an important role in relief of respiratory distress.

Afferent Pathways↗
PubMed1998

Propentofylline potentiates induced ischemic tolerance in gerbil hippocampal neurons via adenosine receptor.

The effect of propentofylline, an adenosine uptake inhibitor, on ischemic tolerance was investigated in the gerbil global ischemia model. Propentofylline was administered 24 hours after short preconditioning ischemia, and animals were subjected to 5-minute ischemia 24 hours thereafter. Propentofylline at a dose of 20 mg/kg intraperitoneally, but not at a dose of 10 mg/kg, significantly potentiated the protective effect of preconditioning ischemia in the CA1 hippocampal neurons. This effect was completely abolished by simultaneous administration of theophylline (20 mg/kg), an adenosine receptor blocker. This finding suggests the involvement of adenosine receptor for the development of ischemic tolerance.

Animals↗
PubMed1998

Expression of telomerase catalytic component, telomerase reverse transcriptase, in human gastric carcinomas.

Telomerase activity is believed to be crucial for cellular immortality, which is considered to participate in the development of a majority of human cancers. Human telomerase reverse transcriptase (TERT) has recently been identified as a catalytic subunit of telomerase. We examined the expression of TERT and other telomerase components such as human telomerase RNA component (hTR, encoded by TERC) and human telomerase-associated protein (TEP1) by reverse transcription-polymerase chain reaction in human gastric carcinomas and non-neoplastic mucosa, in addition to measuring the telomerase activity. Of 20 gastric carcinomas examined, 18 (90%) and 18 (90%) showed increased expression of TERT and higher telomerase activity in comparison with corresponding non-neoplastic mucosa, respectively. Increased expression of hTR/TERC was also observed in 15 (75%) of the gastric carcinomas. Immunohistochemically, strong expression of TERT protein was detected in the nuclei of the tumor cells of all carcinoma tissues, while the expression of TERT in non-neoplastic mucosal cells as well as stromal elements (except lymphocytes) was weak or negative. These findings suggest that increased TERT expression associated with telomerase activity may serve as a novel marker for the diagnosis of stomach cancer.

Aged↗
PubMed1998

In situ mRNA hybridization technique for analysis of human telomerase RNA in gastric precancerous and cancerous lesions.

Telomerase, the ribonucleoprotein enzyme that elongates telomerase, is repressed in normal somatic cells but is reactivated during tumor progression. The purpose of this study was to investigate the localization of human telomerase RNA (hTR) expression in human gastric precancerous and cancerous lesions by using in situ mRNA hybridization (ISH) with avidin-biotin staining. We also examined telomerase activity in these lesions by using hybridization protection assay connected with a telomeric repeat amplification protocol (TRAP/HPA). Analyzed tissue samples were as follows; 132 cases of chronic atrophic gastritis without intestinal metaplasia, 115 incomplete-type intestinal metaplasias, 40 complete-type intestinal metaplasias, 23 hyperplastic polyps, 23 tubular adenomas and 26 adenocarcinomas. In ISH analysis, high levels of hTR expression were observed preferentially in the nuclei at the single-cell level. hTR-expressing cells in carcinomas and adenomas were significantly more frequent than those of the other lesions (P < 0.001). The expression pattern of hTR in carcinoma and adenoma tissues was heterogeneous and similar intratumor heterogeneity was detected in Ki-67 immunoreactivity. Infiltrating lymphocytes in tissue also exhibited high levels of hTR expression. In TRAP/HPA analysis, carcinomas had significantly more frequent positivity for telomerase activity and a higher level of telomerase activity than the other lesions (P < 0.05). However, the amount of telomerase activity did not parallel the expression level of hTR. Our data suggest that hTR expression increases in the early stages of stomach carcinogenesis and that sufficient synthesis of hTR is a prerequisite for telomerase reactivation in tumorigenesis.

Humans↗
PubMed1998

Hypercapnia enhances the development of coughing during continuous infusion of water into the pharynx.

We investigated the effects of increasing CO2 ventilatory drive on the coordination of respiration and reflex swallowing elicited by continuous infusion of distilled water into the pharynx (2.5 ml/min) in 11 normal subjects. Ventilation was monitored using a pneumotachograph and swallowing was recorded by submental electromyogram. The CO2 ventilatory drive was increased by addition of external dead space, while ventilation, the frequency of swallows, and the timing of swallows in relation to the phases of the respiratory cycle were measured at steady-state conditions. We found that the CO2 ventilatory response is not influenced by continuous reflex swallowing but that hypercapnia influences the timing and frequency of these swallows. Signs of aspiration were never observed during continuous infusion of water at eucapnia, but seven of 11 subjects showed laryngeal irritation and/or pending aspiration during hypercapnia, and the incidence of laryngeal irritation was higher the greater the PCO2. Detailed analysis of laryngeal irritations consisting of single coughs in seven subjects revealed that the majority of laryngeal irritations occurred when swallows coincided with expiratory-inspiratory transition or when swallows coincided with inspiration, whereas laryngeal irritation after an expiratory swallow was never observed. These results suggest that the automatic respiratory control system is not influenced by continuous swallowing but that the coordination of swallowing and respiration may be compromised during hypercapnia.

Adult↗
PubMed1998

Effects of negative pressure assisted ventilation on dyspnoeic sensation and breathing pattern.

Although negative pressure assisted ventilation with an assist-control mode may have a potential therapeutic role in the treatment of severe dyspnoea, the effects of negative pressure assisted ventilation with the assist-control mode on dyspnoea and breathing patterns have not been examined. We examined the effects of negative pressure assisted ventilation with the assist-control mode on dyspnoea and breathing patterns produced by a combination of resistive loading and hypercapnia in nine healthy subjects breathing spontaneously. Subjects were asked to rate their sensation of respiratory discomfort using a visual analogue scale. Negative pressure assisted ventilation caused a significant reduction in sensation of respiratory discomfort from a visual analogue scale score of 74 (55-91) (median (range)) before negative pressure assisted ventilation to 34 (15-53) during negative pressure assisted ventilation (p<0.01). During negative pressure assisted ventilation, there were significant changes in breathing patterns characterized by an increase in tidal volume and a decrease in respiratory frequency, while neither minute ventilation nor end-tidal carbon dioxide tension changed. Our results indicate that negative pressure assisted ventilation with the assist-control mode is effective in relief of dyspnoea and that negative pressure assisted ventilation influences the control of breathing to minimize respiratory discomfort.

Adult↗
PubMed1998

A novel insulin sensitizer acts as a coligand for peroxisome proliferator-activated receptor-alpha (PPAR-alpha) and PPAR-gamma: effect of PPAR-alpha activation on abnormal lipid metabolism in liver of Zucker fatty rats.

We investigated the biological activity of a novel thiazolidinedione (TZD) derivative, KRP-297, and the molecular basis of this activity. When administered to obese Zucker fatty rats (obese rats) at 10 mg/kg for 2 weeks, KRP-297, unlike BRL-49,653, restored reduced lipid oxidation, that is, CO2 and ketone body production from [14C]palmitic acid, in the liver by 39% (P < 0.05) and 57% (P < 0.01), respectively. KRP-297 was also significantly more effective than BRL-49,653 in the inhibition of enhanced lipogenesis and triglyceride accumulation in the liver. To understand the molecular basis of the biological effects of KRP-297, we examined the effect on peroxisome proliferator-activated receptor (PPAR) isoforms, which may play key roles in lipid metabolism. Unlike classical TZD derivatives, KRP-297 activated both PPAR-alpha and PPAR-gamma, with median effective concentrations of 1.0 and 0.8 micromol/l, respectively. Moreover, radiolabeled [3H]KRP-297 bound directly to PPAR-alpha and PPAR-gamma with dissociation constants of 228 and 326 nmol/l, respectively. Concomitantly, KRP-297, but not BRL-49,653, increased the mRNA and the activity (1.5-fold [P < 0.01] and 1.8-fold [P < 0.05], respectively) of acyl-CoA oxidase, which has been reported to be regulated by PPAR-alpha, in the liver. By contrast, KRP-297 (P < 0.05) was less potent than BRL-49,653 (P < 0.01) in inducing the PPAR-gamma-regulated aP2 gene mRNA expression in the adipose tissues. These results suggest that PPAR-alpha agonism has a protective effect against abnormal lipid metabolism in liver of obese rats.

Acyl-CoA Oxidase↗
PubMed1998

Negative-strand HCV RNA was not detected in bone marrow cells of patients with HCV infection.

To determine whether hepatitis C virus (HCV) replicates in bone marrow, we investigated positive- and negative-strand HCV RNA in bone marrow cells and fluids, and sera from patients with HCV infection. The study population consisted of 15 patients positive for antibodies to HCV (anti-HCV). Positive- and negative-strands HCV RNA were detected using highly strand-specific rTth reverse transcription-polymerase chain reaction (rTth RT-PCR) followed by Southern blotting analysis. Positive-strand HCV RNA was detected in 12 (80%) serum samples, in 13 (86.7%) bone marrow fluid specimens, and in 6 (40.0%) bone marrow cell samples. Negative-strand HCV RNA was detected in 9 (60.0%) serum samples, 11 (91.7%) fluid specimens, while it was not detected in bone marrow cells. The absence of negative-strand HCV RNA in bone marrow cells suggested that HCV does not replicate in these cells. Negative-strand HCV RNA detected in serum and bone marrow fluid samples may have been due to contamination with circulating HCV RNA from hepatocytes.

Adult↗
PubMed1998

Effect of emeriamine, an inhibitor of fatty acid oxidation, on metabolic fate of a geometrical isomer of linoleic acid in perfused rat liver.

To estimate the relative significance of exogenous vs. endogenous fatty acids in increasing hepatic triacylglycerol secretion following an inhibition of fatty acid oxidation by emeriamine, livers from 2-d-fasting rats were perfused with or without an inhibitor in the presence of a geometrical isomer of linoleate (linolelaidic acid, trans,trans-9,12-octadecadienoic acid). Emeriamine added to the perfusion medium at 2 h of the recirculating perfusion period caused immediate and complete cessation of ketone body production while it increased triacylglycerol and cholesterol secretion by the liver without affecting uptake of exogenous linolelaidic acid. The increase in the triacylglycerol secretion by emeriamine was accompanied by a marked increase in the proportion of linolelaidic acid in this lipid molecule in the perfusate and in the liver. The calculated amounts of exogenous linolelaidate, compared with those of endogenous fatty acids in the secretory triacylglycerol, suggested that the former compared with the latter contributes more to the drug-mediated increase in triacylglycerol secretion. This drug caused a marked reduction of mitochondrial carnitine palmitoyltransferase activity in perfused liver. These results suggest that a blockade of fatty acid oxidation by emeriamine, through an inhibition of carnitine palmitoyltransferase, diverts predominantly the exogenous free fatty acids from oxidation to the esterification pathway and subsequently stimulates the synthesis and secretion of triacylglycerol-rich lipoproteins.

3-Hydroxybutyric Acid↗
PubMed1998

Reciprocal effects of dietary sesamin on ketogenesis and triacylglycerol secretion by the rat liver.

The effects of dietary sesamin (a mixture of sesamin and episesamin, 1:1, w/w) on ketone body production and lipid secretion were studied in isolated perfused liver from rats given sesamin. Feeding sesamin at the dietary level of 0.2% from 14 to 16 d resulted in an enlargement of liver weight. Ketone body production was significantly elevated in the livers perfused with oleic acid in comparison with those perfused without an exogenous-free fatty acid, and sesamin feeding caused a stimulation of ketone body production, especially when exogenous oleic acid was provided. On the other hand, the ratio of beta-hydroxybutyrate to acetoacetate, an index of mitochondrial redox potential, tended to increase in the livers perfused with oleic acid compared with those without fatty acid, thought it was consistently lowered by dietary sesamin. The cumulative secretion of triacylglycerol, but not of cholesterol, by the livers from sesamin-fed rats was decreased markedly, especially when exogenous oleic acid was provided, suggesting an inverse relationship between the rates of ketogenesis and triacylglycerol secretion. These results suggest that dietary sesamin exerts its hypotriglyceridemic effect at least in part through an enhanced metabolism of exogenous-free fatty acid to oxidation at the expense of esterification in rat liver.

3-Hydroxybutyric Acid↗
PubMed1998

[Telomerase: a new marker for cancer diagnosis].

Telomerase, a ribonucleoprotein reverse transcriptase, is expected to be a new marker for cancer diagnosis since it has been reported that high expression of telomerase activity was detected exclusively in germinal tissues and tumor tissues in human body, which is further evaluated by improvement of quantitative assay procedure for telomerase activity in tissue extract and by development of in situ detection method of telomerase protein component in tissue sections.

Biomarkers, Tumor↗
PubMed1998

[Standardization of hemopoietic colony assay reagents].

Several Japanese Red Cross blood centers have begun cooperating with hospitals in peripheral blood stem cell transplantation research. However, most have not yet standardized their techniques or reagents for that purpose yet. Consequently, wide variations are often observed in data from different blood centers, especially for hemopoietic colony assays. We compared our colony assay reagent set with those in three commercial colony assay kits. The best results were obtained with the kit from a manufacturer referred to here as company A. Although our reagent set obtained lower colony values, the CFU-GM, BFU-E, and total colony values correlated well with those obtained using company A's kit (r = 0.74, 0.80, and 0.97, respectively). Company A's kit gave reproducible results even with the use of different lots, and includes reagents that can be stored for up to two years at -20 degrees C. These features highlighted its advantages as a standard reagent set.

Colony-Forming Units Assay↗
PubMed1998

New method to measure telomerase activity by transcription-mediated amplification and hybridization protection assay.

Telomerase is a ribonucleoprotein complex that uses RNA as a template for the addition of telomeric repeats. The development of the telomeric repeat amplification protocol (TRAP), a sensitive PCR-based assay, has facilitated the detection of telomerase activity in small tissue and tumor samples. Telomerase activity is expected to be a new diagnostic and prognostic marker of human cancer. In this study, we applied a non-PCR-based transcription-mediated amplification (TMA) and hybridization protection assay (HPA) to the measurement of telomerase activity by modification of both primers in TMA. We demonstrated that the modified TMA can detect and measure telomerase activity. TMA/HPA is as sensitive and reproducible as conventional TRAP, but is both faster and easier to perform. Furthermore, we found that TMA/HPA was influenced minimally by TRAP inhibitors that may come from clinical samples. TMA/HPA, which is easy, rapid, and applicable to a high-throughput format, should be clinically useful for the detection and monitoring of telomerase activity.

Carcinoma, Hepatocellular↗
PubMed1997

Abnormal telomere dynamics of B-lymphoblastoid cell strains from Werner's syndrome patients transformed by Epstein-Barr virus.

The characteristics of B-lymphoblastoid cell strains transformed by Epstein-Barr virus (EBV) from normal individuals and Werner's syndrome (WRN) patients were compared. We continuously passaged cell strains from 28 WRN patients and 20 normal individuals for about 2 years corresponding to over 160 population doubling levels (PDLs). First, the WRN mutation significantly suppressed the immortalization: all the 28 cell strains from WRN patients, as well as 15 out of 20 cell strains from normal individuals, died out before 160 PDLs mostly without developing a significant telomerase activity. The remaining five cell strains from normal individuals became moderately/strongly telomerase-positive and, three of them were apparently immortalized with an infinitively proliferating activity. Second, the monitoring of the telomere length of both normal and WRN cell strains during the culture period suggests that the WRN gene mutation causes abnormal dynamics of the telomere: (1) a significant proportion of WRN cell strains showed drastic shortening or lengthening of telomere lengths during cell passages compared with normal cell strains, and (2) WRN cell strains terminated their life-span at a wide range of telomere length (between 3.5 and 18.5 Kbp), whereas normal cell strains terminated within a narrow telomere length range (between 5.5 and 9 Kbp). The chromosomal aberration characteristic of WRN cells, including translocation was confirmed in our experiment. We discussed the correlation between the chromosomal instability, abnormal telomere dynamics and inability of immortalization of the WRN B-lymphobloastoid cell strains.

B-Lymphocytes↗
PubMed1997

Decrease in amplified telomeric sequences and induction of senescence markers by introduction of human chromosome 7 or its segments in SUSM-1.

Introduction of human chromosome 7 by microcell-mediated chromosome transfer suppresses indefinite division of SUSM-1, an in vitro established human fibroblast line. This cell line has unusually long telomeric sequences although it lacks detectable telomerase activity. Thus, we examined whether such telomeric sequences change upon introduction of chromosome 7 or its segments. In the microcell hybrids that stopped dividing by introduction of chromosome 7, the telomeric sequences were found to be lost or markedly diminished. Introduction of various fragments (2-40 Mb) of chromosome 7 contained in radiation hybrids gave similar results. On the other hand, the telomeric sequences were not altered significantly in the unsuppressed hybrids, a revertant of one suppressed clone, or subclones of SUSM-1 used as controls. In the suppressed microcell hybrids, the distribution of a mortality marker, mortalin, was changed to the cytosolic type of mortal cells from the immortal type of perinuclear fibres. Also, senescence-associated beta-galactosidase was induced to a level similar to that of normally senesced diploid fibroblasts. These results suggest that human chromosome 7 induces senescence in SUSM-1 by suppressing its telomere maintenance mechanism, which does not depend on telomerase.

Animals↗