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Biomedical subjects

K Katsumata

Publications and source records attributed to K Katsumata.

At least 37 records · Page 2Linked to original sources
PubMed1998

Tissue-specific high-level expression of human endogenous retrovirus-R in the human adrenal cortex.

In an attempt to clarify the biological nature of a human endogenous retrovirus (HERV), HERV-R, which is a single-copy type of HERVs and is conserved as a full-length viral sequence, the expression of HERV-R mRNA in normal autopsied systemic organs was examined by Northern blot analysis. The expression showed different levels among individuals, with the adrenal glands expressing the highest level of HERV-R among all organs tested, except for the placenta. In various adrenal tumors, HERV-R was expressed at high levels in all cortical adenomas but less so in pheochromocytomas. In situ hybridization revealed the expression of HERV-R to be localized in all layers of the adrenal cortex, but not in the medulla. This high-level expression of HERV-R in the adrenal cortex may possibly relate to differentiation and/or steroid production by adrenocortical cells.

Adrenal Cortex↗
PubMed1998

Effect of combination treatment with a vitamin D analog (OCT) and a bisphosphonate (AHPrBP) in a nude mouse model of cancer-associated hypercalcemia.

Hypercalcemia represents one of the important paraneoplastic syndromes affecting morbidity and mortality of cancer patients. We and others have demonstrated that vitamin D analogs with little calcemic activities suppress the transcription of the parathyroid hormone-related peptide (PTHrP) gene, a major humor responsible for cancer hypercalcemia, and thereby prevent the development of hypercalcemic syndrome. The present study was undertaken: to compare the therapeutic efficacy of a vitamin D analog, 22-oxa-1,25-dihydroxyvitamin D3 (OCT), and a bisphosphonate (disodium 3-amino-1-hydroxypropylidene-1,1-bisphosphonate pentahydrate [AHPrBP]), an inhibitor of osteoclastic bone resorption, on cancer-induced hypercalcemia; and to see if the effect could be enhanced by combination treatment, using a nude mouse model implanted with a human pancreas carcinoma (FA-6). After a single intravenous administration, OCT (5 microg/kg of body weight [BW]) was as effective as AHPrBP (10 mg/kg of BW) in lowering blood ionized calcium levels in tumor-bearing nude mice, and their combination further enhanced the therapeutic effect. Although AHPrBP lost its efficacy after repeated injections, OCT was still effective after the third administration. The therapeutic effect of OCT in cancer hypercalcemia was observed in four other human tumors, including another pancreas carcinoma (PAN-7), two squamous cell carcinomas of the lung (KCC-C1 and LC-6), and a squamous carcinoma of the pharynx (PHA-1), all of which elaborated PTHrP into the circulation. Treatment with OCT resulted in a decrease in circulating PTHrP levels by approximately 50% in two representative models. However, the mechanism underlying the antihypercalcemic effect of OCT seemed complex, involving inhibition of PTHrP production, suppression of excessive bone resorption, and an antitumor activity. OCT also markedly inhibited the body weight loss with tumor growth, while AHPrBP, which exhibited a similar antihypercalcemic effect, was less effective than OCT in preventing cachexia. The anticachectic activity of their combination did not exceed that of OCT alone, suggesting a hypercalcemia-dependent as well as an independent mechanism of cancer cachexia. It is concluded that OCT may be useful, either as a single agent or in combination with bisphosphonates, for the treatment of cancer-associated hypercalcemia and cachexia.

Animals↗
PubMed1997

Fragile mitochondrial DNA: the missing link in the apoptotic neuronal cell death in Parkinson's disease.

The oxidative stress theory, the mitochondrial (mt) hypothesis, and the apoptosis hypothesis are proposed as the cause of neuronal cell death in Parkinson's disease (PD). However, the direct link between them has remained unknown. Recently, the mt control of nuclear apoptosis is documented that collapse of mt transmembrane potential due to energy crisis leads to release of apoptotic protease activating-factors into cytosol and subsequently nuclear DNA fragmentation. However, an endogenous factor responsible for the energy crisis under physiological conditions is missing. Here we report the missing factor as that mtDNA in the striatum of a parkinsonian patient fragments into 134 types of deleted pieces, being detected by the total detection system for mtDNA deletion. The system has documented that the mtDNA is extremely susceptible to hydroxyl radical damage, hence to oxidative stress, enough to cause the cellular energy crisis. The extensive fragility of mtDNA in brain stem could link the oxidative stress up with the apoptotic neuronal cell-death of PD.

Adolescent↗
PubMed1997

Hydrogen-exchange kinetics of reduced alpha-lactalbumin bound to the chaperonin GroEL.

alpha-Lactalbumin in which all the disulfide bonds are fully reduced (RLA) is known to bind strongly to the chaperonin GroEL. Although RLA is more unfolded than the native state and the molten globule state of alpha-lactalbumin, the CD spectrum of RLA in the far-UV region shows that RLA is not fully unfolded but has an appreciable amount of secondary structure. To investigate whether the secondary structure elements present in RLA are responsible for the recognition of RLA by GroEL or not, we have examined the hydrogen-exchange kinetics of RLA in the presence and absence of GroEL. Our results show that the hydrogen-exchange kinetics of RLA bound to GroEL is identical to that of free RLA. This implies that the secondary structure elements in RLA are not important for the recognition by GroEL, but the unstructured parts of RLA that are not relevant to the stability of the secondary structure provide strong recognition sites of RLA.

Chaperonin 60↗
PubMed1997

Suppressed cardiac and electroencephalographic arousal on apnea/hypopnea termination in elderly patients with cerebral infarction.

The goal of the present investigation is to show the clinical significance of arousal response at termination of apnea/hypopnea in patients with sleep apnea syndrome (SAS) after cerebral infarction. We polygraphically assessed "cardiac arousal," which is defined as an abrupt increase in heart rate at a termination of sleep apnea/hypopnea, and electroencephalographic (EEG) arousal. There were six elderly subjects, bedridden after cerebral infarction, with SAS aged 71-87 years (mean 72.3 years) and 11 age-matched patients with SAS aged 61-78 years (mean 62.3 years) as controls. The following sleep parameters were measured: number of apneas per hour (apnea index [AI]), number of hypopneas per hour (hypopnea index [HI]), summation of the two (apnea/hypopnea index [AHI]), and duration in which nocturnal oxygen saturation was decreased below 90% (duration of SaO2 < 90%). We calculated the ratio of apnea/hypopnea per hour with cardiac arousal to total apnea/hypopneas (XI) (% cardiac arousal [XI/AHI x 100]) and the ratio of that with EEG arousal (YI) (% EEG arousal [YI/AHI x 100]). Between the two groups, we found no significant difference in body mass index, the ratio of central apnea to total apnea/hypopnea, AHI, duration of apnea/hypopnea, lowest SaO2, and duration of SaO2 < 90%. Compared with controls, % cardiac and % EEG arousals were significantly lower in patients with cerebral infarction. In contrast, the ratio of HI to AHI was significantly higher in patients with cerebral infarction than in control subjects. Our findings indicate that cardiac and EEG arousals at termination of apnea/hypopnea are significantly suppressed in elderly patients with SAS after cerebral infarction, which may provide useful information on the pathophysiology of SAS in patients with cerebrovascular disease.

Aged↗
PubMed1997

[Clinical analysis of adjuvant chemotherapy using 5-fluorouracil, leucovorin and cis-diamminedichloroplatinum for patients with advanced and recurrent gastric cancer].

The chemotherapy combining 5-FU, CDDP, and LV was conducted in 17 patients with advanced and recurrent gastric cancer. The regimen consisted of 5-FU (by continual infusion 600 mg/m2/day for 5 days), CDDP (low-dose consecutive drip infusion, 2 hours 20 mg/m2/day for 3 days) and LV (by bolus infusion 20 mg/ m2/day for 5 days). Advanced gastric cancer was found in 12 cases (operation performed in 9 cases and 7 cases resectable) and recurrent in 5 cases. Macroscopic judgment of efficacy in 10 recurrent and inoperable cases revealed CR in 1 patient, PR in 5 patients, NL in 2, and PD in 2 patients. The overall response rate was 60.0%. There were 7 resectable cases, 4 PR patients, 1 MR and 2 NC patients. The overall response rate was 57.1%. Operations were done in 9 of 12 patients with advanced gastric cancer. The histological effects in 7 cases with resectable cases were as follows: 1 patient of grade 0, 2 patients of grade 1a, 3 patients of grade 1b, and 1 patient of grade 2. The main adverse reactions were gastrointestinal symptoms, but in 3 cases thrombocytopenia was found. This chemotherapy for advanced and recurrent gastric cancer shows excellent clinical efficacy.

Adenocarcinoma↗
PubMed1997

[Endogenous retroviruses in autoimmune diseases].

Endogenous retroviruses (ERVs) and those related genes are thought to be originated from integration of infectious retroviruses to germ cells or evolved from transposable genetic elements. Some of them can make biological effects on activities of hosts, by promoting the expression of flanking genes or producing certain regulatory proteins. If those mechanisms occur on cells in immune networks, immunological dysregulation including autoimmunity will develop. ERVs can also produce proteins serving as auto-antigens, followed by autoimmune responses. In this article, studies up to date on ERVs of animals and humans are shortly reviewed, related to immunological disorders to autoimmune diseases, showing some examples.

Animals↗
PubMed1997

[Efficacy of combination chemotherapy with mitoxantrone, vincristine, doxifluridine and prednisolone for recurrence of breast cancer].

We treated fifteen patients with recurrent breast cancer by a combination of mitoxantrone (8 mg/m i.v., day 1), vincristine (1.2 mg/m i.v., day 1), doxifluridine (800 mg/body po, everyday) and prednisolone (30 mg/body po, day 1-7). Cycles were repeated every 3 weeks and all patients received more than 2 cycles. A response to treatment was observed in 9 of 15 evaluable patients (60.0%) with 4 complete remissions and 5 partial remissions. Eight patients were previously exposed to anthracyclines. In 5 of 7 cases with no previous chemotherapy, treatment was effective, and in 4 of 8 cases previous chemotherapy was effective. The toxicity was primarily leucopenia (86.7%), and 9 patients received G-CSF therapy. Other toxicities (alopecia, neurologic and general fatigue) were mild. Two patients with heart failure were recognized and treated with other therapy. This chemotherapy is effective for the treatment of recurrent breast cancer.

Administration, Oral↗
PubMed1997

[Tissue-specific expression of human endogenous retrovirus mRNA and its regulation by cytokines in vitro].

To investigate biological roles of human endogenous retroviruses (ERVs), the author examined the viral mRNA expression in the normal systemic organs in vivo and its regulation by cytokines in cultured cells. The following evidence suggesting biological activities of a human ERV, ERV3, was obtained. First, the ERV3 mRNA was demonstrated at different levels in organs, and at consistently high levels in adrenal glands from all individuals and in all adrenocortical adenomas examined, by Northern hybridization. In situ hybridization revealed that the ERV3 expression was localized in all three layers of the adrenal cortex, but not in the medulla. These results suggest that the ERV3 expression may relate to the cellular differentiation and/or steroid production of adrenocortical cells. Second, the amount of ERV3 mRNA in cultured endothelial cells from human umbilical vein was significantly increased with any of TNF-alpha, IL-1 beta or IL-1 alpha stimulation but decreased with IFN-gamma treatment, by a quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) with competitive PCR. The collective evidence suggests that the ERV3 expression may be upregulated at the inflammatory sites of vessels in vivo, and that the ERV3 expression may, therefore, play certain pathogenic roles in diseases, including collagen and vascular diseases in man.

Adrenal Cortex↗
PubMed1996

Dominant forces in the recognition of a transient folding intermediate of alpha-lactalbumin by GroEL.

GroEL is known to retard the refolding of apo-alpha-lactalbumin by interacting with the molten globule state of the protein. In order to investigate the dominant forces in this interaction, the GroEL-affected kinetic refolding of apo-alpha-lactalbumin from its acidic molten globule state was studied at different temperatures and in the presence of different kinds of monovalent cations at a fixed temperature (25 degrees C), by stopped-flow fluorescence measurements. The binding constant between GroEL and alpha-lactalbumin in the molten globule state was evaluated quantitatively from the kinetic refolding curves in the absence and presence of GroEL. The binding was found to be entropy-driven at room temperature and the heat capacity change for the binding was found to be largely negative (-3.6 kJ mol-1.K-1), indicating that GroEL binds to alpha-lactalbumin through hydrophobic interactions. The study of the effect of different monovalent cations at various ionic strengths shows that the binding is strengthened by electrostatic screening by ions, demonstrating the importance of electrostatic interactions. The relationship of these results with a putative target recognition site of GroEL will be discussed.

Binding Sites↗
PubMed1996

Age-related extensive fragmentation of mitochondrial DNA into minicircles.

In normal human hearts, a progressive age-related fragmentation of mitochondrial (mt) DNA into various-sized deleted (delta) mtDNA up to 358 types was documented by a novel total-detection system for deletions. The delta mtDNA lacking replication origin(s), minicircles, accumulated up to 280 types out of the 358, suggesting a yet unknown replication mechanism in human. Wild-type mtDNA decreased linearly down to 11% of the total with age negatively correlated with delta mtDNA and oxidized nucleoside, 8-hydroxydeoxyguanosine. A remarkable mirror image observed in delta mtDNA size distribution as well implies that random hydroxyl-radical attacks resulted in double-strand break and rejoining of mtDNA as a preferable mechanism to form various delta mtDNA of closed circular duplex. These facts support the 'redox mechanism of aging.'

Adolescent↗