PubMed Health⌕ Search

Biomedical subjects

A Utsumi

Publications and source records attributed to A Utsumi.

At least 19 recordsLinked to original sources
PubMed2006

Molecular level damages of low power pulsed laser radiation in a marine bacterium Pseudoalteromonas carrageenovora.

AIM: To study the molecular level damages in a marine bacterium, Pseudoalteromonas carrageenovora, exposed to low power pulsed laser radiation from an Nd:YAG laser. METHODS AND RESULTS: The laser damages in bacterial DNA were monitored by studying the formation of apurinic/apyrimidinic (AP) sites. Molecular probe kits were used for this purpose. Occurrence of lesions in the cell walls was monitored under a transmission electron microscope (TEM). The results showed that laser radiation significantly increased the number of AP sites in the bacterial DNA. This increase corresponded to the laser fluence (J cm(-2)) and to the duration of laser irradiation. TEM observation showed the occurrence of lesions in bacterial cell walls upon laser irradiation. CONCLUSIONS: It is concluded that bacteria exposed to laser irradiation suffers DNA damages and resulted in broken cell walls. These events led to bacterial mortality. These are in addition to the mechanisms reported earlier such as the photochemical reactions occurring inside the cells upon exposure to low power laser. SIGNIFICANCE AND IMPACT OF THE STUDY: These results help us to understand the mechanisms of bacterial mortality on exposure to low power pulsed laser irradiation and are useful in formulating a laser treatment strategy to kill bacteria.

Cell Wall↗
PubMed2001

Laboratory evaluation of a microangioscope for potential percutaneous cerebrovascular applications.

A laboratory-based study of the physical and performance characteristics of a new 0.25-mm-thin microangioscope was performed. The microangioscope tested was compatible with currently available microcatheters, but its tip was considerably stiff and of limited radiopacity. Poor image quality and difficult image interpretation were further drawbacks. Intensive efforts are directed at addressing current limitations and testing further innovations that could pave the way for future performance in neurovascular endoscopy.

Angiography↗
PubMed2000

Tyrosine hydroxylase gene microsatellite polymorphism associated with insulin resistance in depressive disorder.

A high association between type 2 diabetes mellitus and depressive illness has been reported. Insulin resistance during depressive illness might contribute to the linkage between depression and type 2 diabetes. To determine whether the genetic polymorphisms of the tyrosine hydroxylase ([TH] HUMTH01) and insulin (INS-VNTR) genes contribute to insulin resistance in depressive illness, we analyzed the association between the polymorphisms and insulin resistance in 41 Japanese patients with depressive disorder, 204 normal control subjects, 161 cohort subjects with normal glucose tolerance (NGT) and without depressive symptomatology, and 59 NGT subjects with depressive symptomatology. The depressive patients had a significantly lower insulin sensitivity index (SI) than the control subjects (P= .016). Depressive NGT subjects had a significantly higher homeostasis model assessment (HOMA) insulin resistance index [HOMA(R)] than the nondepressive NGT subjects (P < .0001). The depressive patients and NGT subjects had more HUMTH01 allele 7 (TH7) than the controls and nondepressive NGT subjects. SI was significantly lower in patients with the TH7/7 homozygote versus patients with the other genotypes and the controls. TH7 was associated with higher HOMA(R) as compared with the other alleles in the NGT subjects. Insulin resistance was associated with depressive disorders. The HUMTH01 and INS-VNTR were associated with insulin resistance and depressive symptoms.

Adult↗
PubMed1999

Insulin resistance in patients with depression and its changes in the clinical course of depression: a report on three cases using the minimal model analysis.

It has been reported that depression and diabetes mellitus often occur together, and insulin resistance has been observed in patients with depression. For further understanding of the relationship of depression to insulin resistance, three patients with depression were given the oral glucose tolerance test (OGTT) and the frequently sampled intravenous glucose tolerance test (FSIGT) with minimal model analysis before and after antidepressant treatment. Depressive patients showed decreased glucose tolerance, enhanced insulin secretion, and diminished insulin sensitively during OGTT and FSIGT. These abnormalities were resolved after their recovery from depression without changes in body weight or diet.

Adult↗
PubMed1998

Plasma GH responses to GHRH, arginine, L-dopa, pyridostigmine, sequential administrations of GHRH and combined administration of PD and GHRH in Turner's syndrome.

To investigate GH secretory capacities in patients with Turner's syndrome, GHRH, arginine, L-dopa and pyridostigmine (PD) were administered singly and GHRH was administered sequentially for 3 days. In addition, plasma GH and TSH responses to GHRH and TRH after pretreatment with PD were analyzed to investigate whether the hypothalamic cholinergic somatostatinergic system functioned normally. The maximal GH responses to GHRH, L-dopa and PD were significantly smaller in Turner's syndrome (no.=14) than in normal short children (NSC, no.=14). However, there was no difference in plasma GH responses to arginine between the two groups. In ten patients with Turner's syndrome, the plasma GH response to GHRH did not improve even after the sequential 3-day administrations. Although plasma GH and TSH responses to GHRH and TRH were significantly enhanced by the pretreatment of PD in NSC (no.=12), these responses were not enhanced in Turner's syndrome. Plasma GH response to GHRH in Turner's syndrome with normal body fat was still significantly lower than in NSC. It is therefore concluded that somatotroph sensitivity to GHRH is decreased in Turner's syndrome and that this may be due to the primary defects of the somatotrophs rather than to the increased body fat. In addition, the network of cholinergic-somatostatinergic systems seemed to be impaired in these patients, while the activity of hypothalamic somatostatin neurons was thought to be maintained.

Adolescent↗
PubMed1998

Secretory mechanisms of growth hormone (GH)-releasing peptide-, GH-releasing hormone-, and thyrotropin-releasing hormone-induced GH release in patients with acromegaly.

The GH secretory mechanism of GH-releasing hexapeptide (GHRP-6), GHRH, and TRH were studied in vivo and in vitro in seven patients with acromegaly. In an in vivo study, these patients showed clear GH responses to single administration of GHRP (four of four patients), GHRH (seven of seven patients), and TRH (seven of seven patients) and enhanced responses to GHRP plus GHRH (two of four patients) or TRH plus GHRH (six of six patients). In an in vitro dispersed cell study, the majority of patients examined also showed clear GH responses to GHRP (four of four patients), GHRH (six of six patients), and TRH (four of four patients) and an enhanced response to GHRP plus GHRH (three of three patients) or TRH plus GHRH (three of four patients). In one patient (no. 3), GHRP plus forskolin (adenylate cyclase activator), but not GHRP plus phorbol 12-myristate 13-acetate (protein kinase C activator), additively enhanced the GH response. Nordihydroguaiaretic acid (NDGA; inhibitor of arachidonic cascade) inhibited GH release induced by GHRP, TRH, GHRH, TRH plus GHRH, or GHRP plus GHRH, but did not inhibit basal GH secretion. In contrast, NDGA distinctly elevated intracellular cAMP levels in another patient (no. 7) when coadministered with GHRP, GHRH, or GHRP plus GHRH, whereas cAMP levels were not modified by single administration of GHRP and NDGA. The GH response to the combined administration of GHRP and GHRH was synergistic in this patient, but was additive in the other two patients. It is concluded that GHRP, TRH, and GHRH directly stimulate in vivo and in vitro GH release from human somatotropinomas, and GHRP and TRH mainly exert their action through activation of the phosphatidylinositol-protein kinase C pathway, whereas GHRH exerts its action through the adenylate cyclase-protein kinase A pathway. These three agents seem to release GH via the arachidonic cascade.

Acromegaly↗
PubMed1997

Brain-gut induction of heat shock protein (HSP) 70 mRNA by psychophysiological stress in rats.

Restraint water-immersion stress-induced expression of heat shock protein (HSP)70 mRNA in the cerebral cortex and stomach of rats was evaluated by Northern blotting. Cerebral and gastric HSP70 mRNA significantly increased in the 6 h-stressed rats and the amount of mRNA measured as optical densities was highest in the 12 h-stressed rats. These data confirmed our previous observations and suggest that families of HSPs play a salient cytoprotective role in stress-vulnerable organs.

Animals↗
PubMed1996

The inhibitory effects of growth hormone-releasing hormone (GHRH)-antagonist on GHRH, L-dopa, and clonidine-induced GH secretion in normal subjects.

The relative inhibitory potency of GHRH-Antagonist (GHRH-Ant) to GHRH(1-44)NH2 and mechanism of L-dopa- or clonidine-induced GH release were studied in seven normal subjects using GHRH-Ant. One hundred micrograms of GHRH-Ant (iv for 75 min) did not inhibit plasma GH responses to bolus injection of 100 micrograms and 10 micrograms GHRH or simultaneous infusion of 5 micrograms GHRH (iv for 75 min). However, 200 micrograms GHRH-Ant (iv for 75 min) significantly inhibited GH release, which was induced by simultaneous infusion of 5 micrograms GHRH. Although 100 micrograms GHRH-Ant could not significantly inhibit L-dopa-induced GH release, 200 micrograms GHRH-Ant almost completely inhibited the response. Similarly, the same dose of GHRH-Ant markedly inhibited the GH-releasing activity of clonidine. It is concluded that the inhibitory potency of GHRH-Ant on GHRH(1-44)NH2 is relatively weak (about 1/60 in molar base), and that L-dopa- or clonidine-induced GH release seems to be mediated by the release of hypothalamic GHRH.

Adult↗
PubMed1996

Plasma GH responses to human GHRH-antagonist in normal subjects.

The effect of GHRH-antagonist [(N-Ac-Tyr1, D-Arg2) GRF-(1-29)-NH2] on plasma GH morning and evening secretion was evaluated in 14 normal subjects (10 males, 4 females, aged 19-25 years). Plasma GH was determined using a high sensitivity IRMA kit (detection limit, 0.006 micrograms/l). After intravenous infusion of GHRH-antagonist (100 micrograms/100 ml saline over 75 min) in the morning, plasma GH remained constant during the 150 min post-infusion (N = 6). In contrast, when GHRH-antagonist was administered in the evening, plasma GH showed a clear and gradual decrease through the initial 90 min and returned to baseline levels at 150 min. Plasma GH values were also significantly lower from 75 min to 135 min when compared to physiological fluctuations in plasma GH (P < 0.05). Other anterior pituitary hormones remained unaffected by GHRH-antagonist. In conclusion, our data suggest that evening basal GH secretion, but not morning GH secretion, is maintained by endogenous GHRH.

Adult↗
PubMed1995

Psychophysiological stress induces heat shock cognate protein (HSC) 70 mRNA in the cerebral cortex and stomach of rats.

Families of 70 kDa heat shock proteins have essential roles in cellular coping to noxious stimuli. However, their roles in psychophysiological stress have not been precisely clarified. We tested our hypothesis that heat shock cognate protein (HSC)70 messenger RNA would increase in stress-vulnerable organs under psychophysiological stress. In control rats, cerebral HSC70 mRNAs were constitutively expressed while gastric HSC70 mRNAs were scarcely identified. Restraint-water immersion stress significantly increased the level of cerebral HSC70 mRNAs for 6 h and 12 h. Stress for 6 h with recovery for 6 h induced more gastric HSC70 mRNA levels than that without recovery, while stress for 12 h expressed the highest gastric HSC70 mRNA levels. Hypothermia, induced by water immersion, excluded a possible role of hyperthermia in inducing HSC70 mRNA. Our results point to a crucial cytoprotective role for families of heat shock proteins in stress-vulnerable brain-gut link in mammals under psychophysiological stress.

Animals↗
PubMed1995

Enhanced plasma GH responses to simultaneous administration of TRH and GHRH in patients with primary hypothyroidism.

The mechanism of aberrant GH responses to TRH was indirectly evaluated in 7 patients with primary hypothyroidism. All patients showed GH response to TRH. When TRH was administered together with GHRH, the plasma GH response was much greater than after a single administration of TRH or GHRH (TRH+GHRH vs. TRH or GHRH: max. delta GH, 16.4 +/- 3.2 vs. 5.4 +/- 1.3 or 6.0 +/- 0.8 microgram/L; AUC, 1282.7 +/- 234.7 vs. 384.0 +/- 95.0 or 441.8 +/- 66.2, both P < 0.01). The combined administration of TRH and GHRH caused an additive, but not a synergistic, GH response. In contrast, 8 normal subjects showed neither any plasma GH response to TRH nor enhancement by TRH of GHRH-induced GH response following combined administration. It is concluded that the sites of action of TRH seemed to be different from GHRH in patients with primary hypothyroidism.

Adult↗
PubMed1994

The evaluation of hypothalamic somatostatin tone using pyridostigmine and thyrotropin releasing hormone in patients with acromegaly.

To indirectly evaluate the hypothalamic somatostatin (SS) tone in patients with acromegaly, the effects of pyridostigmine (PD), a cholinesterase inhibitor which can inhibit hypothalamic SS secretion, on TRH-induced TSH secretion and the effects of SMS 201-995 on TSH or GH secretion were studied in acromegalic patients (31-69 yr, n = 10), normal young (21-24 yr, n = 7) and normal old male subjects (62-71 yr, n = 7). After pretreatment with PD (60 mg po, -30 min), normal young subjects showed significantly enhanced TSH responses to TRH (500 micrograms i.v., 0 min) compared to single administration of TRH, whereas normal old and acromegalic patients did not show such enhancement. Plasma TSH response to a single administration of TRH in acromegalic patients was significantly lower than that of normal young and old subjects. Although normal young and old subjects showed significantly enhanced GH responses to GHRH (100 micrograms i.v. at 0 min) after the pretreatment with PD (60 mg, -30 min), no such enhancement was observed in acromegalic patients. In contrast, the decrement in plasma TSH after SMS 201-995 administration was similar between normal subjects (5 young 5 old) and 7 acromegalic patients. Further, the maximal plasma GH decrement after administration was significantly greater in acromegalic patients than in the 5 normal young and 5 old subjects p < 0.01). In conclusion, hypothalamic SS tone does not appear to be elevated in acromegalic patients compared to normal young and probably old subjects.

Acromegaly↗
PubMed1994

Enhanced GH responses to combined administration of GHRP and GHRH in patients with acromegaly.

Plasma GH responses to GH-releasing peptide (GHRP) were studied in 11 patients with active acromegaly. Ten of these patients showed plasma GH increases to GHRP (100 micrograms i.v.), whereas every patient showed GH increases to TRH (500 micrograms i.v.) and GHRH (100 micrograms i.v.). When GHRP was administered together with GHRH to the 10 GHRP responders, plasma GH responses were synergistically enhanced. However, combined administration of GHRP and TRH did not enhance the response. The GH response pattern and mean time to the peak value were similar to TRH but were different from GHRH. There was no correlation in the maximum GH increment between GHRP and TRH or GHRP and GHRH. It is concluded that GHRP stimulated GH release in the majority of acromegaly patients. The mode of action of GHRP might be similar to TRH and different from GHRH, although the sites of action of GHRP seemed to be different from those of TRH and GHRH.

Acromegaly↗
PubMed1993

Anti-HIV (human immunodeficiency virus) activity of sulfated paramylon.

Sulfated derivatives of paramylon, a water-insoluble (1-3)-beta-D-glucan from Euglena gracilis, significantly inhibited the cytopathic effect of human immunodeficiency virus (HIV-1, HIV-2) and the expression of HIV antigen in cultured MT-4, MOLT-4 cells and human peripheral blood mononuclear cells. Native paramylon, N,N-dimethylaminoethyl paramylon, N,N-diethylaminoethyl paramylon, 2-hydroxy-3-trimethylammoniopropyl paramylon chloride, and carboxymethyl paramylon had little or no anti-HIV activity. The anti-HIV activity of the sulfated paramylon derivatives depended on the number of sulfate groups, and the molecular weight. Paramylon sulfate significantly inhibited HIV-1 binding to MT-4 cells. The anti-coagulant activity of the sulfated paramylon derivatives also depended on the number of sulfate groups, but was generally lower than that of dextran sulfate. The results point to the potential of paramylon sulfate in the treatment of HIV infection.

Animals↗
PubMed1993

Plasma GH response to the sequential 3 day administrations of GHRH followed by arginine infusion in patients with idiopathic GH deficiency and normal short children.

To study the site of lesions in idiopathic growth hormone (GH) deficiency (IGHD), growth hormone releasing hormone (GHRH) was administered sequentially for 3 days to 19 patients with IGHD, 3 patients with GH deficiency (GHD) secondary to hypothalamic tumors, and 7 normal short children (NSC). GHRH (100 micrograms) was injected as a bolus on days 1 and 3, and was infused over 60 min on day 2. Of 19 patients with IGHD, 6 showed an improved GH response (group A), 5 a decreased response (group B) and the remaining 8 an unchanged response (group C) to sequential administration of GHRH. The response was unchanged in patients with secondary GHD or NSC. There was no significant correlation between the patterns of GH response and the findings on pituitary MR images or the delivery state at birth in IGHD patients. Ten patients with IGHD (4 of group A; 3 each of groups B & C) and 2 NSC showed much greater GH responses to arginine (0.5 g/kg i.v. for 30 min) injected with preceding GHRH than to arginine injected without preceding GHRH. These results indicate that hypothalamic lesions were primarily responsible for GH deficiency in about 60% of the patients with IGHD (groups A and B), and group C might have more severe hypothalamo-pituitary damages than the other groups. Hypothalamic somatostatin neurons seems to be functioning to a degree even in severe IGHD patients.

Adolescent↗
PubMed1992

Plasma growth hormone (GH) responses to corticotropin-releasing hormone in patients with acromegaly--the effect of dexamethasone pretreatment and the comparison with GH responses to thyrotropin-releasing hormone, gonadotropin-releasing hormone and GH-releasing hormone.

It has been reported that paradoxical GH responses to corticotropin-releasing hormone (CRH) occur in only few patients with acromegaly. However, we have observed such responses in 7 of 14 active acromegalic patients. Therefore, we have studied the GH responses to thyrotropin-releasing hormone (TRH) (500 micrograms, iv), gonadotropin-releasing hormone (LHRH) (100 micrograms, iv) and GH-releasing hormone (GHRH) (100 micrograms, iv) in these patients to examine the relationships between the GH responses to CRH and the responses to these hypothalamic hormones. Further, these patients received human CRH (1-41) NH2 (100 micrograms, iv) with or without dexamethasone (Dex) pretreatment (1 mg/100 ml saline, iv, from -30 to +30 min) to study the mechanism of CRH-induced GH secretion, and a perifusion experiment was performed using adenoma tissue obtained at surgery from one patient (10(-7) M CRH and TRH were added) to elucidate whether CRH acts directly at the pituitary level. Aberrant GH responses induced by CRH were found in 7 of 14 (50%) acromegalic patients (TRH responders: 10/13, 77%; LHRH responders: 2/9, 22%; GHRH responders: 10/12, 83%). In these patients, percent GH increment induced by CRH ranged from 81 to 144% (Mean +/- SE, 118 +/- 8%), and the GH peak (19 +/- 3 min) appeared as early as after TRH (23 +/- 4 min, N = 10).(ABSTRACT TRUNCATED AT 250 WORDS)

Acromegaly↗
PubMed1992

Simultaneous administration of TRH and sulpiride caused additive but not synergistic PRL responses in normal subjects.

In order to study the mode of action of TRH and sulpiride in man, we administered TRH (500 micrograms, iv) and sulpiride (DA D2 receptor antagonist, 100 mg, im) simultaneously to 6 normal females (20-21 yr). Normal females showed significantly greater PRL increments and AUC in response to the combined administration compared to a single administration of each agent (P < 0.05-0.01), while the increment and AUC in response to the combination did not exceed the sum of those responses to a single administration. In contrast, the combined administration of TRH and sulpiride did not elicit an enhanced response of plasma TSH. These results indicate that the sites of action of TRH and sulpiride might be different from each other, and these agents work additively with no interaction in human lactotrophs.

Adult↗