Biomedical subjects

K Shinohara

Publications and source records attributed to K Shinohara.

At least 37 records · Page 2Linked to original sources

PubMed2001

Impairment of maze learning in rats by restricting environmental space.

We previously reported that the restriction of environmental space attenuates spontaneous locomotor activity and hippocampal acetylcholine release. To examine the effect of the restriction of environmental space on spatial learning function, male rats were individually housed in a cylindrical large cage (diameter=35 cm) or small cage (diameter=19 cm) for 5 days. Eight-arm radial maze performance was examined to evaluate spatial learning and memory functions. The task was performed once a day between 21:00 and 22:00 h in the dark phase. Although all rats learned and performed the task, those in the small cage had lower scores and took more trial time than those in the large cage. These results suggest that the restriction of environmental space impairs spatial learning in the dark phase in rats.

Acetylcholine↗

PubMed2001

Remission of acute myeloblastic leukemia after severe pneumonia treated with high-dose methylprednisolone.

We report a case of acute myeloblastic leukemia (AML)-M2 (by French-American-British classification) with t(8;21) (q22:q22) that was complicated with severe pneumonia. The patient tested positive by fluorescence in situ hybridization (FISH) for AML1 splitting and positive by reverse transcriptase polymerase chain reaction (RT-PCR) for chimeric AML1/MTG8 messenger RNA (mRNA), which indicated splitting of the MTG8 gene on chromosome 8 (q22) and the AMLI gene on chromosome 22 (q22). High-dose methylprednisolone was administered, and the leukemic cells disappeared without chemotherapy, although dysplastic hematopoietic cells were observed transiently after the first therapy. After the disappearance of leukemic cells, FISH for AML1 splitting was negative, and real-time PCR results for quantitative chimeric AML1/ MTG8 mRNA were less than the detectable level, however, RT-PCR results for AML1/MTG8 mRNA remained positive. These findings suggest that the patient acquired morphological, cytogenetic. and possibly molecular genetic remission by the synergistic effects of severe infection and high-dose methylprednisolone.

Aged↗

PubMed2001

Evaluation of the relative contribution of p53-mediated pathway in X-ray-induced apoptosis in human leukemic MOLT-4 cells by transfection with a mutant p53 gene at different expression levels.

There are several pathways leading to apoptosis. It is not clear whether cells choose one of them or use multiple processes when they commit to apoptosis. MOLT-4 cells undergo apoptosis after X-irradiation through the p53-dependent pathway and/or ceramide signal. To evaluate the relative contribution of these pathways, we studied effects of the expression of various levels of transfected murine mutant p53 cDNA (TGC-->CGC of codon 173, corresponding to codonl76 in human p53) on the induction of apoptosis in X-irradiated or heated MOLT-4 cells. When survival was determined by the dye-exclusion test at 24 h after irradiation, the percentage of X-ray- or heat-induced dead cells was markedly decreased, depending on the expression level of mutant p53 protein in transfected clones. The appearance of apoptotic cells as determined by morphological changes was also decreased. These inhibitions were almost complete at 24 h after irradiation with X-rays in the case of the highest-expressing clone. p21 WAF1 protein was increased in MOLT-4 cells after X-irradiation, but not in the transfectant. These results suggest that murine mutant p53 protein has a dominant-negative effect against normal p53 in MOLT-4, and that the X-ray-induced apoptosis in MOLT-4 is fully p53-dependent.

Apoptosis↗

PubMed2001

Lipolytic enzyme effect on small low-density lipoprotein particles in women treated with estrogen.

OBJECTIVE: To test whether hydrolysis of low-density lipoprotein (LDL) triglyceride by lipolytic enzymes decreases the size of LDL particles in women treated with estrogen replacement. METHODS: Fifteen postmenopausal women received 0.625 mg conjugated equine estrogens daily for 3 months. Plasma concentrations of total cholesterol, triglyceride, and high-density lipoprotein (HDL) cholesterol were measured before and after therapy. We also assayed levels of total, free, and esterified cholesterol, triglyceride, and protein in LDL. Plasma samples were incubated at 37C for 24 hours and LDL fractions were isolated by ultracentrifugation. After LDL samples were further incubated with or without lipoprotein lipase (500, 700, and 1000 ng/mL) at 37C for 24 hours, LDL triglyceride, LDL protein, and the diameter of LDL particles were measured. RESULTS: Estrogen decreased total cholesterol and increased triglyceride and HDL cholesterol in plasma. Estrogen treatment decreased the ratio of cholesteryl ester/protein, whereas the ratio of triglyceride/protein increased. Estrogen decreased LDL particle diameter. Incubation of plasma increased the ratio of LDL triglyceride/protein from 0.40 +/- 0.14 to 0.48 +/- 0.15 (P <.05) and decreased the ratio of LDL cholesteryl ester/protein from 1.17 +/- 0.25 to 1.09 +/- 0.22 (P <.05), but LDL particle diameter did not change. Incubation of LDL with lipoprotein lipase reduced the LDL triglyceride/protein ratio, and decreased the diameter of LDL particles from 25.61 +/- 0.87 nm to 24.89 +/- 0.88 nm (500 ng/mL, P <.05), 24.62 +/- 1.20 nm (700 ng/mL, P <.05), and 24.67 +/- 1.19 nm (1000 ng/mL, P <.05). CONCLUSION: In women treated with estrogen, hydrolysis of triglyceride in LDL particles might be accompanied by reduced particle size.

Cholesterol↗

PubMed2001

Five-year retrospective, multi-institutional pooled analysis of cancer-related outcomes after cryosurgical ablation of the prostate.

OBJECTIVES: To define the potential role of cryosurgical ablation of the prostate (CSAP) as a treatment option for patients with localized prostate carcinoma (PCA), we performed a retrospective outcomes analysis of a large database of patients undergoing CSAP constructed from five institutions and compared this with matching outcomes from contemporary reports of patient outcomes after radiotherapy. METHODS: A total of 975 patients who underwent CSAP as primary therapy from January 1993 to January 1998 with sufficient outcomes data available were identified. Patients were stratified into three groups on the basis of their clinical features. Biochemical-free survival (BFS), post-CSAP biopsy results, and post-CSAP morbidities were calculated and recorded. RESULTS: The median follow-up for all patients was 24 months. The percentages of patients in the low, medium, and high-risk groups were 25%, 34%, and 41%, respectively. For prostate-specific antigen thresholds of less than 0.5 and less than 1.0 ng/mL, the 5-year actuarial BFS ranged from 36% to 61% and 45% to 76%, respectively, depending on the risk category. Overall, the positive biopsy rate was 18%. Morbidities included impotence in 93%, incontinence in 7.5%, rectourethral fistula in 0.5%, and transurethral resection of the prostate in 13% of patients (10% approved warming catheters versus 40% nonapproved). CONCLUSIONS: For each risk group, the 5-year BFS and positive biopsy rate after CSAP was comparable to matching outcomes reported after radiotherapy. Morbidities also seemed comparable, with impotence rates higher and rectal injury rates lower after CSAP than after radiotherapy. These data indicate that CSAP can be performed with low morbidity and can produce cancer-related results comparable to those reported for patients undergoing radiotherapy.

Biomarkers, Tumor↗

PubMed2001

Increase in the number of detectable preoptic glutamic acid decarboxylase 67-immunoreactive cells in immature male rats.

Gonadotropin-releasing hormone (GnRH) neurons are mainly located in the anterior preoptic area (aPOA) and gamma-aminobutyric acid (GABA) is known as a potent regulator of the GnRH neurons. To examine the development of the GABAergic system in the aPOA, immunocytochemistry of glutamic acid decarboxylase 67 (GAD(67)) was performed in immature (postnatal d16, d25 and d30) and mature (postnatal 10 weeks) male rats. All immunocytochemical procedures were simultaneously performed. In the lateral part of the aPOA, the detectable number of GAD(67)-immunoreactive cells was small in the d16 group, but significantly increased in the d25, d30 and mature groups, up to 2.7, 4.8 and 5.7 times the number in the d16 group, respectively. In the diagonal band of Broca (DBB), the number was also small in the d16 group, and significantly increased in the d25, d30 and mature groups upto 1.8, 2.2 and 2.8 times the number in the d16 group, respectively. However, in the cingulate cortex, no significant developmental change was observed. These results suggest that the development of the GABAergic system in the lateral aPOA and the DBB occurs before sexual maturation of male rats.

Aging↗

PubMed2001

Circadian and photic regulation of cryptochrome mRNAs in the rat pineal gland.

Expressions of Cry1 and Cry2 mRNA in the rat pineal gland were examined by Northern blot. The levels of Cry1 and Cry2 transcript had a marked circadian rhythm with peaks at circadian time (CT) 20 in constant darkness. But the amplitude of the Cry1 rhythm was higher than that of the Cry2 rhythm. Furthermore, a significant increase in Cry1 mRNA levels was caused by light pulse given at CT 16 but not at CT 4, but the expression of Cry2 was not significantly induced by light pulses given at either CT 4 or CT 16. These results suggest that Cry1 in the pineal gland is regulated by photic and circadian information but Cry2 is only regulated by circadian information.

Animals↗

PubMed2001

Effect of estrogen on the expression of Cry1 and Cry2 mRNAs in the suprachiasmatic nucleus of female rats.

To determine whether estrogen has an effect on clock genes in the suprachiasmatic nucleus (SCN), we examined the effect of estrogen on the expression of Cry1 and Cry2 mRNAs in the SCN of female rats. Ovariectomized rats were injected with 20 microg 17beta-estradiol at zeitgeber time (ZT) 6 and ZT 18 and killed 24 h after the treatment. Northern blot revealed that the expression of Cry2 mRNA was significantly decreased in the SCN of estrogen-treated rats at both time points [correction]. But estrogen did not affect Cry1 mRNA levels in the SCN at any ZT. These results suggested that Cry1 and Cry2 mRNAs in the SCN were differently regulated by estrogen.

Animals↗

PubMed2001

Menstrual and circadian variations in time perception in healthy women and women with premenstrual syndrome.

A time production test was performed in seven normal females and seven females with premenstrual syndrome (PMS). We used a time production test for six time intervals (6, 12, 24, 36, 48, 60 s). Time production tests were performed at 08:00, 14:00 and 20:00 h in the follicular, early luteal and late luteal phases (LLP), respectively. The results are as follows. (1) Normal females showed diurnal variations in time production only in the follicular phase (FP). In this phase, they overproduced time at 08:00 h suggesting that the interval clock in normal females was slowest in the morning. (2) Normal females showed menstrual variations in time production only at 20:00 h. They overproduced time in the LLP suggesting that the interval clock in normal females was slowest in the LLP. (3) Neither diurnal nor menstrual variation was found in PMS subjects at any menstrual stage or at any time of the day. These results suggest that the interval timing system in normal females is under the control of ovarian steroid hormones and the circadian clock, but the control of ovarian steroid hormone or the circadian clock does not operate in PMS subjects.

Adolescent↗

PubMed2001

Influences of cholinergic neurotoxin ethylcholine aziridinium ion on circadian rhythms in rats.

To investigate whether damages of cholinergic neurons in the brain produce aging-like changes in circadian rhythms, we examined the influences of intracerebroventricular injection of cholinergic neurotoxin ethylcholine aziridinium ion (AF64A, 5 nmol/5 microl) on circadian rhythms in rats, by measuring locomotor activity and body temperature with the automatic behavioral measurement system combined with the telemetry. Daily rhythms in locomotor activity and body temperature were observed in AF64A-treated rats under a 12:12 h light:dark (LD) cycle, however, in AF64A-treated rats, the amplitude of activity and temperature rhythms was significantly decreased, the phase of the both rhythms was advanced and the amount of activity was decreased, compared with control rats. Locomotor activity and body temperature also showed a circadian rhythm in AF64A-treated rats under the constant dark condition with the period similar to that in the control rats. The present findings are in accordance with the observation in aged animals in which cholinergic hypofunction are often observed, suggesting that hypofunctions of the cholinergic systems in the brain might be involved in aging-like changes in the circadian rhythms.

Acetylcholine↗

PubMed2001

Melatonin protects fetal rat brain against oxidative mitochondrial damage.

Our objective was to investigate the effects of melatonin on the free radical-induced oxidative damage to mitochondria in fetal rat brain. Female Wistar rats on day 19 of pregnancy were used. Melatonin (10 mg/kg) or vehicle (control) was injected intraperitoneally 60 min prior to laparotomy for removal of the fetuses. The mitochondrial fraction was isolated from the fetal rat brain of each group. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were measured. As indicators of mitochondrial respiratory activity, we determined the respiratory control index (RCI) and the adenosine 5-diphosphate/oxygen (ADP/O) ratio in the presence and absence of 2.5 microM hypoxanthine and 0.02 units/mL xanthine oxidase. Mitochondrial lipid peroxidation was determined by measuring the concentration of thiobarbituric acid reactive substances in fetal brain mitochondria in the presence or absence of 2.5 microM hypoxanthine, 0.02 units/mL xanthine oxidase, and 50 microM FeSO4. The free radical-induced rates of inhibition of mitochondrial RCI and the ADP/O ratio were both significantly lower in the fetal rat brains treated with melatonin compared with those of the controls (RCI, 44.25 +/- 15.02% vs. 25.18 +/- 5.86%, P < 0.01; ADP/O ratio, 50.74 +/- 23.05% vs. 13.90 +/- 7.80%, P < 0.001). The mitochondrial lipid peroxidation induced by free radicals was significantly reduced in the melatonin-treated group compared with the controls (484.2 +/- 147.2%) vs. 337.6 +/- 61.0%, P < 0.01). Pretreatment with melatonin significantly increased the activity of GSH-Px (20.35 +/- 5.27 to 28.93 +/- 11.01 mU/min mg(-1) protein, P < 0.05) in fetal rat brain mitochondria, but the activity of SOD did not change significantly. Results indicate that the administration of melatonin to the pregnant rat may prevent the free radical-induced oxidative mitochondrial damage to fetal rat brain by a direct antioxidant effect and the activation of GSH-Px.

Adenosine Diphosphate↗

PubMed2001

Melatonin stimulates glutathione peroxidase activity in human chorion.

In preeclampsia, placental production of lipid peroxides is abnormally increased, while placental glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities are decreased. Administration of melatonin, a powerful scavenger of oxygen free radicals, also may protect the placenta from free radical-induced damage by increasing the activity of antioxidant enzymes. To test this hypothesis we administered melatonin to pregnant women before they underwent voluntary interruption of pregnancy between 7 and 9 wk of gestation. Melatonin (6 mg) was administered orally at 12:00 hr, and samples of chorion and maternal blood were obtained at the time of the procedure, 1, 2 or 3 hr later. We measured the melatonin concentration in maternal serum and activities of GSH-Px and SOD and levels of melatonin in chorionic homogenates. Melatonin administration was reflected by markedly increased melatonin concentrations in maternal serum and in chorion, with peak levels achieved 1 hr after melatonin administration (serum, 46.87 +/- 10.87 nM/L; chorionic homogenate, 4.36 +/- 1.56 pmol/mg protein). Between 1 and 3 hr after melatonin administration, GSH-Px activity in chorionic homogenates increased significantly (P < 0.001), with peak levels occurring at 3 hr (51.68 +/- 3.22 mU/mg protein per min, 137.3% of GSH-Px activity in untreated control subjects). No significant changes in chorionic SOD activity occurred during the 3-hr post-administration period. These results indicate that exogenous melatonin increases GSH-Px activity in the chorion and thereby may protect indirectly against free radical injury. Melatonin could be useful in treating preeclampsia and possibly other clinical states involving excessive free radical production, such as intrauterine fetal growth retardation and fetal hypoxia.

Abortion, Induced↗

PubMed2001

Melatonin protects against ischemia/reperfusion-induced oxidative damage to mitochondria in fetal rat brain.

We investigated the effects of melatonin on ischemia/reperfusion-induced oxidative damage to mitochondria in fetal rat brain. The utero-ovarian arteries were occluded bilaterally for 20 min in female Wistar rats on day 19 of pregnancy to induce fetal ischemia. Reperfusion was achieved by releasing the occlusion and restoring circulation for 30 min. A sham operation was performed in control rats. Melatonin (10 mg/kg) or vehicle was injected intraperitoneally 60 min prior to occlusion. We measured the respiratory control index (RCI) and the adenosine 5-diphosphate (ADP)/oxygen ratio as indicators of mitochondrial respiratory activity, as well as the concentration of thiobarbituric acid-reactive substances (TBARS) in the mitochondria of fetal brain. Ischemia/reperfusion significantly elevated the concentration of TBARS and significantly reduced the RCI as well as the ADP/oxygen ratio. Melatonin treatment reversed the ischemia/reperfusion-induced reductions in the RCI (2.29 +/- 0.06-2.64 +/- 0.09, P < 0.05) and in the ADP/oxygen ratio (1.48 +/- 0.03-1.57 +/- 0.02, P < 0.05), and also reduced the elevation in concentration of TBARS (11.00 +/- 0.34-7.57 +/- 0.74 nM/mg protein, P < 0.01), resulting in values similar to those in untreated, sham-ischemic animals. The results indicate that administration of melatonin to pregnant rats may prevent ischemia/reperfusion-induced oxidative mitochondrial damage in fetal rat brain.

Adenosine Diphosphate↗

PubMed2001

Melatonin protects against oxidative mitochondrial damage induced in rat placenta by ischemia and reperfusion.

We assessed the effects of melatonin, a powerful scavenger of oxygen free radicals, on ischemia/reperfusion-induced oxidative damage to mitochondria in the rat placenta. In Wistar rats at day 19 of pregnancy, feto-placental ischemia was induced by occluding both utero-ovarian arteries for 20 min. Reperfusion was achieved by releasing the occlusion and restoring circulation for 30 min. Melatonin solution or the vehicle alone was injected intraperitoneally at dose of 10 mg/kg 1 hr before occlusion. Sham-ischemic animals were treated with vehicle. Each group consisted of 10 pregnant rats. We measured placental mitochondrial respiratory control index (RCI; a marker of mitochondrial respiratory activity), the ratio of the added adenosine 5-diphosphate (ADP) concentration to consumption of oxygen during state 3 respiration (ADP/O), and the concentration of thiobarbituric acid reactive substances (TBARS) in each group. RCI and ADP/O were significantly decreased by ischemia/reperfusion, while TBARS were increased. Melatonin prevented these changes. These results indicate that exogenous melatonin protects against ischemia/reperfusion-induced oxidative damage to mitochondria in rat placenta. Melatonin could be useful in treating preeclampsia and possibly other clinical states involving excess free radical production, such as fetal growth restriction and fetal hypoxia.

Adenosine Diphosphate↗

PubMed2001

Melatonin protects against oxidized low-density lipoprotein-induced inhibition of nitric oxide production in human umbilical artery.

We evaluated the antioxidative effect of melatonin on the oxidized low-density lipoprotein (LDL)-induced impairment of nitric oxide (NO) production in human umbilical artery, which may be the prime cause of endothelial dysfunction in pre-eclampsia. Umbilical artery sections with intact endothelium were obtained from healthy pregnant women who were delivered between 37 and 40 wk of gestation. The production of NO in the umbilical arteries was stimulated by adding L-arginine followed by incubation for 60 min. NO concentrations were estimated by measuring nitrite ions (NO(2) using high-performance liquid chromatography. LDL was oxidized by incubation with 5 microM CuSO(4) at 37 degrees C for 4 hr, followed by dialysis at 4 degrees C for 24 hr. Prior to the addition of L-arginine, the segments were treated with native or oxidized LDL (0, 50, 100, 200, 400 microg/mL), or were pre-treated with either mannitol (50 mM) or melatonin (20, 100, 500 microM) before adding oxidized LDL. Changes in L-arginine-induced NO(2)(-) production were expressed as a percentage of NO(2)(-) production at the end of pre-incubation. Treatment with oxidized LDL significantly reduced L-arginine-induced NO(2)(-) production (P<0.05), while NO(2)(-) production did not change by incubation with native LDL. Pre-treatment with melatonin significantly increased NO(2)(-) production that had been decreased by oxidized LDL (P<0.05). Similarly, pre-treatment with mannitol reversed the oxidized LDL-induced reduction in NO(2)(-) production (P<0.05). These results indicate that melatonin protects against oxidized LDL-induced inhibition of NO production in the endothelium of human umbilical arteries, most likely through its ability to scavenge hydroxyl radicals.

Adult↗

PubMed2001

Renal insufficiency accelerates atherosclerosis in patients with type 2 diabetes mellitus.

Diabetes mellitus is a strong risk factor for the progression of atherosclerosis. In patients with chronic renal failure on hemodialysis, advanced atherosclerosis is reported to be present. We examined how renal insufficiency affects intima-medial thickness (IMT) of the carotid and femoral arteries in patients with type 2 diabetes mellitus. IMT was measured by B-mode ultrasonography in 115 patients with type 2 diabetes mellitus (65 men, 50 women; 58 +/- 13 years old). The IMT of the carotid and the femoral artery of patients with creatinine clearance less than 80 mL/min (n = 55) were significantly greater than those of patients with creatinine clearance 80 mL/min or greater (n = 60; P < 0.01 and P < 0.05). Linear regression analyses showed that there was a significant negative correlation between creatinine clearance and IMT of the carotid artery (r = -0.330; P < 0.001) and femoral artery (r = -0.336; P < 0.001). Multiple regression analyses revealed that age and creatinine clearance significantly and independently affected the IMT of the carotid artery (R(2) = 0.176; P < 0.0001), and age, duration of diabetes, and smoking affected the IMT of the femoral artery (R(2) = 0.287; P < 0.0001). These findings show that decreased renal function accelerates atherosclerosis in patients with type 2 diabetes mellitus and that chronic renal failure is a significant, independent risk factor for carotid atherosclerosis in these patients.

Age Factors↗

PubMed2001

Ancestral MADS box genes in Sugi, Cryptomeria japonica D. Don (Taxodiaceae), homologous to the B function genes in angiosperms.

In flowering plants, flower organ identity is controlled by the ABC genes, including several MADS box genes. We present two MADS box genes of a conifer, Cryptomeria japonica D. Don. The genes, CjMADS1 and CjMADS2, were related to the angiosperm B function genes which determine the identities of petals and stamens. A phylogenetic analysis showed that these genes form a new clade outside the angiosperm B group, that is, PISTILLATA (PI) and APETALA3 (AP3) lineages. CjMADS1 had a PI-group specific motif and CjMADS2 had AP3-group specific motifs at the C terminal end, respectively. CjMADS1 was expressed in male strobili (or cones) throughout its development, while CjMADS2 was transiently expressed during male strobilus development. The specific expression in the male reproductive organ indicated that the B function is maintained in gymnosperms. Our cladistic analysis suggests that the gene duplication event which generated B function gene lineages predates the divergence of angiosperms and gymnosperms and that the gene duplication which produced the two genes of C. japonica occurred in an ancestral conifer species.

Amino Acid Sequence↗

PubMed2001

Inhibition of the light-independent synthesis of chlorophyll in pine cotyledons at low temperature.

Cotyledons of Japanese black pine (Pinus thunbergii) were yellow when they developed in darkness at 8 degrees C since the light-independent synthesis of chlorophyll was almost completely inhibited in these cotyledons. The level of chlorophyll in dark-grown cotyledons was less than one-twentieth of that in light-grown cotyledons at the same temperature. In the yellow cotyledons, levels of transcripts of cab, rbcS, rbcL and psbA genes were quite high. The large and small subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase were also detected at relatively high levels in yellow cotyledons. However, the accumulation of the two apoproteins of the light-harvesting chlorophyll a/b-binding protein of PSII was limited because of the limited supply of chlorophyll.

Chlorophyll↗