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Biomedical subjects

M Ozaki

Publications and source records attributed to M Ozaki.

At least 73 records · Page 4Linked to original sources
PubMed2000

Resistance to endotoxin shock in transgenic mice overexpressing endothelial nitric oxide synthase.

BACKGROUND: Nitric oxide (NO) plays a central role in the pathogenesis of septic shock. However, the role of the NO produced by endothelial NO synthase (eNOS) in septic shock is still unclear. We examined the effect of chronic eNOS overexpression and the role of eNOS-derived NO in lipopolysaccharide (LPS)-induced septic shock using eNOS transgenic (Tg) mice. METHODS AND RESULTS: LPS was intraperitoneally injected into Tg and control mice. No differences existed in the peak plasma nitrate and nitrate levels induced by LPS between the 2 genotypes. In LPS-treated control mice, blood pressure progressively declined and reached 60% of basal levels (from 97+/-3 to 59+/-3 mm Hg) 24 hours after LPS injection. In contrast, the blood pressure of LPS-treated Tg mice fell only 15% from basal levels (from 84+/-4 to 71+/-4 mm Hg) after the first 6 hours and, thereafter, it remained at this level. LPS-induced increases in the expression of the mRNA of both vascular cell adhesion molecule-1 and intracellular adhesion molecule-1 in the lungs were significantly lower in Tg mice than in control mice. LPS-induced pulmonary leukocyte infiltration and increases in lung water content were also significantly attenuated in Tg mice. Histological examination revealed that lung injury after LPS injection was milder in Tg mice. Furthermore, Tg mice exhibited enhanced survival from LPS-induced septic shock compared with control mice. CONCLUSIONS: Chronic eNOS overexpression in the endothelium of mice resulted in resistance to LPS-induced hypotension, lung injury, and death. These effects are associated with the reduced vascular reactivity to NO and the reduced anti-inflammatory effects of NO.

Animals↗
PubMed2000

"Deep-forehead" temperature correlates well with blood temperature.

PURPOSE: To evaluate the accuracy and precision of "deep-forehead" temperature with rectal, esophageal, and tympanic membrane temperatures, compared with blood temperature. METHODS: We studied 41 ASA physical status 1 or 2 patients undergoing abdominal and thoracic surgery scheduled to require at least three hours. "Deep-forehead" temperature was measured using a Coretemp thermometer (Terumo, Tokyo, Japan). Blood temperature was measured with a thermistor of a pulmonary artery. Rectal, tympanic membrane, and distal esophageal temperatures were measured with thermocouples. All temperatures were recorded at 20 min intervals after the induction of anesthesia. We considered blood temperature as the reference value. Temperatures at the other four sites were compared with blood temperature using correlation, regression, and Bland and Altman analyses. We determined accuracy (mean difference between reference and test temperatures) and precision (standard deviation of the difference) of 0.5 degrees C to be clinically acceptable. RESULTS: "Deep-forehead" temperature correlated well with blood temperature as well as other temperatures, the determination coefficients (r2) being 0.85 in each case. The bias for the "deep-forehead" temperature was 0.0 degrees C, which was the same as tympanic membrane temperature and was smaller than rectal and esophageal temperatures. The standard deviation of the differences for the "deep-forehead" temperature was 0.3 degrees C, which was the same as rectal temperature. CONCLUSIONS: We have demonstrated that the "deep-forehead" temperature has excellent accuracy and clinically sufficient precision as well as other three core temperatures, compared with blood temperature.

Aged↗
PubMed2000

Anti-insulin receptor autoantibodies in a patient with type B insulin resistance and fasting hypoglycemia.

We studied a patient with systemic lupus erythematosus and type B insulin resistance who showed almost complete normalization of postprandial plasma glucose in 3 months and a transient occurrence of fasting hypoglycemia from day 35 (i.e. the 35th day of hospitalization) to day 77. To determine the clinical relevance of the biological ability of anti-insulin receptor antibodies (anti-IRAb), we made multiple preparations of the patient's dialyzed serum and IgG. Dialyzed serum prepared on day 1 showed 95% inhibition of insulin binding. The binding inhibition was, however, decreased parallel to the normalization of insulin sensitivity. For 2DG uptake, 6.2 microM IgG purified on 3 different days (days 7, 35 and 78, designated IgG-NOV, -JAN, and -FEB, respectively) stimulated 2DG uptake into CHO-hIR at 3.4-, 3.1-, and 1.5-fold, respectively. Phosphotyrosine immunoblotting revealed that apparent insulin receptor autophosphorylation was visible only with IgG-NOV, not with the IgG-JAN or -FEB. Mutation of tyrosine-960 or lysine-1018 of the insulin receptor failed to transduce the IgG's stimulatory effect. IgG-NOV was not able to stimulate the autophosphorylation of the human IGF-I receptor. In the present study, the insulin binding inhibitory activities of the dialyzed sera prepared at different time points were shown to be altered parallel to insulin sensitivity in vivo. Stimulatory activities of the patient's IgG were, however, discordant for the occurrence of fasting hypoglycemia observed in vivo. Other pathogenic factors or mechanisms in addition to the insulin-like action of the anti-IRAb may be also required to fully understand the development of fasting hypoglycemia in type B insulin resistance.

Animals↗
PubMed2000

Chromosaponin I stimulates the sugar taste receptor cells of the blowfly, Phormia regina.

Chromosaponin I (CSI), a gamma-pyronyl-triterpenoid saponin isolated from pea and other leguminous plants, stimulates the growth of roots in a variety of plants. In the present work, we introduce CSI as a sugar taste substance for the blowfly, Phormia regina. The blowfly has taste chemosensilla on the labellum. The sensory receptor cells in the chemosensillum are highly specialized for the tastes of sugar, salt and water, respectively. Application of CSI induced the feeding response of blowflies including full proboscis extension. CSI also induced impulses of the sugar taste receptor cell in the LL-type sensillum. The optimum concentration of CSI in these responses was 0.1 mM which is much lower than that of sucrose. Based on the comparison of dose-response relationships, CSI is 100 times more effective than sucrose in stimulating the sugar taste receptor cells. CSI-induced impulses appeared after a significant latency compared with sucrose. As far as we know, this is the first report describing that a natural saponin induces sugar responses in insects. CSI is a unique saponin because of its bifunctional property in plants and insects.

Animals↗
PubMed2000

Preferential potentiation by nitric oxide of spontaneous inhibitory postsynaptic currents in rat supraoptic neurones.

Magnocellular neurones in the supraoptic nucleus and paraventricular nucleus express mRNA for nitric oxide synthase (NOS) and the expression becomes more prominent when the release of vasopressin or oxytocin is stimulated. It has also been reported that NO donors inhibit the electrical activity of supraoptic nucleus neurones, but the mechanism involved in the inhibition remains unclear. In the present study, to know whether modulation of synaptic inputs into supraoptic neurones is involved in the inhibitory effect of NO, we measured spontaneous excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs) from rat supraoptic nucleus neurones in slice preparations identified under a microscope using the whole-cell mode of the slice-patch-clamp technique. The NO donor, S-nitroso-N-acetylpenicillamine (SNAP), reversibly increased the frequency of spontaneous IPSCs mediated by GABAA receptors, without affecting the amplitude, indicating that NO potentiated IPSCs via a presynaptic mechanism. The NO scavenger, haemoglobin, suppressed the potentiation of IPSCs by SNAP. On the other hand, SNAP did not cause significant effects on EPSCs mediated by non-NMDA glutamate receptors. The membrane permeable analogue of cGMP, 8-bromo cGMP, caused a significant reduction in the frequency and amplitude of both IPSCs and EPSCs. The results suggest that NO preferentially potentiates the inhibitory synaptic inputs into supraoptic nucleus neurones by acting on GABA terminals in the supraoptic nucleus, possibly via a cGMP-independent mechanism. The potentiation may, at least in part, account for the inhibitory action of NO on the neural activity of supraoptic neurones.

Animals↗
PubMed2000

Association of remnant-like particle cholesterol with coronary artery disease in patients with normal total cholesterol levels.

BACKGROUND: Limited information is available as to whether there is a difference in the association of lipid and fibrinolytic variables with coronary artery disease according to the presence or absence of elevated serum total cholesterol. We examined the levels of various lipid and fibrinolytic variables including remnant-like particle cholesterol (RLP-C). RLP-C is a recently established simple assay method for the estimation of triglyceride-rich lipoprotein remnants. METHODS AND RESULTS: Levels of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), triglyceride, lipoprotein(a), RLP-C, uric acid, blood glucose, tissue plasminogen activator, tissue plasminogen activator inhibitor type 1, antithrombin III, and protein C were measured in 208 patients who underwent diagnostic coronary angiograms. Of these 208 patients, 57 were hypercholesterolemic (> or =220 mg/dL) and 151 were normocholesterolemic. HDL-C showed significant differences between patients with and those without angiographically determined coronary artery stenosis in both hypercholesterolemic and normocholesterolemic patients (P =.0025 and P =.0003, respectively). Both RLP-C and uric acid showed significant differences only in the normocholesterolemic subgroup (P =.0006 and P =.0060, respectively). This difference in uric acid was not significant by multivariable analysis. The ratio of RLP-C/HDL-C was demonstrated to be highly significantly (P <.0001) associated with coronary artery stenosis in patients with normal total cholesterol, whereas there was no statistically significant association in the hypercholesterolemic patient subgroup. CONCLUSIONS: Our current study disclosed that RLP-C levels are strongly associated with coronary artery disease, especially in patients with normal total cholesterol levels. Moreover, RLP-C/HDL-C ratio may be even more significantly associated with the presence of coronary artery stenosis in normocholesterolemic patients.

Adult↗
PubMed2000

Inhibition of the Rac1 GTPase protects against nonlethal ischemia/reperfusion-induced necrosis and apoptosis in vivo.

Reperfusion of ischemic tissue results in the generation of reactive oxygen species that contribute to tissue injury. The sources of reactive oxygen species in reperfused tissue are not fully characterized. We hypothesized that the small GTPase Rac1 mediates the oxidative burst in reperfused tissue and thereby contributes to reperfusion injury. In an in vivo model of mouse hepatic ischemia/reperfusion injury, recombinant adenoviral expression of a dominant negative Rac1 (Rac1N17) completely suppressed the ischemia/reperfusion-induced production of reactive oxygen species and lipid peroxides, activation of nuclear factor-kappa B, and resulted in a significant reduction of acute liver necrosis. Expression of Rac1N17 also suppressed ischemia/reperfusion-induced acute apoptosis. The protection offered by Rac1N17 was also evident in knockout mice deficient for the gp91phox component of the phagocyte NADPH oxidase. This work demonstrates the crucial role of a Rac1-regulated oxidase in mediating the production of injurious reactive oxygen species, which contribute to acute necrotic and apoptotic cell death induced by ischemia/reperfusion in vivo. Targeted inhibition of this oxidase, which is distinct from the phagocyte NADPH oxidase, should provide a new avenue for in vivo therapy aimed at protecting organs at risk from ischemia/reperfusion injury.-Ozaki, M., Deshpande, S. S., Angkeow, P., Bellan, J., Lowenstein, C. J., Dinauer, M. C., Goldschmidt-Clermont, P. J., Irani, K. Inhibition of the Rac1 GTPase protects against nonlethal ischemia/reperfusion-induced necrosis and apoptosis in vivo.

Animals↗
PubMed2000

Rac1 inhibits TNF-alpha-induced endothelial cell apoptosis: dual regulation by reactive oxygen species.

Reactive oxygen species (ROS) have been implicated as mediators of tumor necrosis factor-alpha (TNF) -induced apoptosis. In addition to leading to cell death, ROS can also promote cell growth and/or survival. We investigated these two roles of ROS in TNF-induced endothelial cell apoptosis. Human umbilical vein endothelial cells (HUVECs) stimulated with TNF produced an intracellular burst of ROS. Adenoviral-mediated gene transfer of a dominant negative form of the small GTPase Rac1 (Rac1N17) partially suppressed the TNF-induced oxidative burst without affecting TNF-induced mitochondrial ROS production. HUVECs were protected from TNF-induced apoptosis. Expression of Rac1N17 blocked TNF-induced activation of nuclear factor-kappa B (NF-kappaB), increased activity of caspase-3, and markedly augmented endothelial cell susceptibility to TNF-induced apoptosis. Direct inhibition of NF-kappaB through adenoviral expression of the super repressor form of inhibitor of kappaBalpha (I-kappaB S32/36A) also increased susceptibility of HUVECs to TNF-induced apoptosis. Rotenone, a mitochondrial electron transport chain inhibitor, suppressed TNF-induced mitochondrial ROS production, proteolytic cleavage of procaspase-3, and apoptosis. These findings show that Rac1 is an important regulator of TNF-induced ROS production in endothelial cells. Moreover, they suggest that Rac1-dependent ROS, directly or indirectly, lead to protection against TNF-induced death, whereas mitochondrial-derived ROS promote TNF-induced apoptosis.

Adenoviridae↗
PubMed2000

Comparison of infrared thermometer with thermocouple for monitoring skin temperature.

OBJECTIVE: To test the hypothesis that the infrared thermometer (Genius) is comparably useful with thermocouples that are routinely used for skin temperature monitoring. DESIGN: Prospective, controlled, not blinded study. SETTING: Operating room of a university hospital. SUBJECTS: Ten healthy male volunteers. INTERVENTIONS: Volunteers were minimally clothed and were initially warmed by a forced air warmer until they became vasodilated at the finger and the foot for approximately 30 mins. Subsequently, they were kept in the room with no blanket. MEASUREMENTS AND MAIN RESULTS: Skin temperatures were measured continuously with the Mon-a-Therm thermocouple and were also measured with the Genius thermometer just before and after the warming and subsequently every 10 mins for 70 mins. Forearm and finger-tip skin temperatures and skin-surface temperature gradients (from arm to finger and from calf to toe) measured by the Genius thermometer were compared with those measured by the Mon-a-Therm thermocouple using linear regression and Bland and Altman statistics. Forearm temperature and finger-tip temperature ranged from approximately 31 degrees to approximately 36.5 degrees C (87.8-97.7 degrees F) and approximately 22.5 degrees to approximately 36 degrees C (72.5-96.8 degrees F), respectively. Gradients (from arm to finger and from calf to toe) ranged from approximately -3 degrees to approximately 10 degrees C (26.6-50.0 degrees F) and approximately -3 degrees to approximately 11 degrees C (26.6-51.8 degrees F), respectively. Correlations between the temperatures measured by the Genius thermometer and those by the Mon-a-Therm thermocouple were similar and reliable. The correlation coefficients were as follows: 0.78 at forearm, 0.97 at finger-tip, and 0.97 at skin-surface temperature gradients. CONCLUSIONS: The infrared thermometer with a special probe is useful to measure the change of skin-surface temperatures and to evaluate the severity of shock in patients.

Adult↗
PubMed2000

Alfentanil reduces the febrile response to interleukin-2 in humans.

OBJECTIVE: Manifestation of intraoperative fever is impaired by volatile anesthetics and muscle relaxants. Opioids are common anesthetic adjuvants and remain the dominant treatment for postoperative surgical pain and sedation of critically ill patients. The effect of opioids on normal thermoregulatory control is well established. However, the extent to which these drugs might inhibit fever remains unknown. Accordingly, we tested the hypothesis that relatively low plasma concentrations of the mu-receptor agonist alfentanil reduce fever magnitude. DESIGN: Prospective, randomized, crossover study. SETTING: Outcomes Research Laboratory, at the Department of Anesthesia and Perioperative Care, University of California, San Francisco. PATIENTS: Eight healthy male volunteers, aged 25-31 yrs, each studied on three separate days. INTERVENTION: Each volunteer was given an intravenous injection of 30 IU/g interleukin (IL)-2, followed 2 hrs later by 70 IU/g. One hour after the second dose, the volunteers were randomly assigned to three doses of alfentanil: a) none (control); b) a target plasma concentration of 100 ng/mL; and c) a target concentration of 200 ng/mL. Opioid administration continued for 5 hrs. METHODS AND MAIN RESULTS: Alfentanil significantly reduced the febrile response to pyrogen, decreasing integrated tympanic membrane temperatures from 7.5+/-2.2 degrees C x hr on the control day, to 4.9+/-1.5 degrees C x hr with 100 ng/mL alfentanil, and to 5.1+/-1.7 degrees C x hr with 200 ng/mL alfentanil (p = .011). Peak temperatures were also significantly reduced from 38.5+/-0.4 degrees C on the control day, to 38.0+/-0.4 degrees C on the 100 ng/mL-alfentanil day and 38.0+/-0.6 degrees C on the 200-ng/mL day (p = .019). Plasma cytokine concentrations increased after IL-2 administration, roughly in proportion to the elevation in core temperature. However, cytokine concentrations did not differ significantly among the treatment groups. CONCLUSION: Alfentanil significantly reduced the febrile response to IL-2 administration. However, the reduction was comparable at plasma concentrations near 100 and 200 ng/mL. These data indicate that concentrations of opioids commonly observed in critical care patients significantly inhibit the manifestation of fever.

Adult↗
PubMed2000

Comparison of endothelium-dependent relaxation in carotid arteries from Japanese white and Watanabe heritable hyperlipidemic rabbits.

Modifications by atherosclerosis of endothelium-dependent and -independent relaxations were evaluated in carotid arteries isolated from Watanabe heritable hyperlipidemic (WHHL; age 20-29 months) and age-matched Japanese white (JW) rabbits. Marked, patchy atherosclerotic lesions were observed in all WHHL rabbit arteries. Endothelium-dependent relaxations induced by acetylcholine, partly depressed by N(G)-nitro-L-arginine (L-NA), were significantly inhibited in the WHHL rabbit arteries with atherosclerosis, compared with those in the arteries without atherosclerotic lesions from JW and WHHL rabbits. No difference was observed in the relaxation caused by superoxide dismutase in these arteries. Conversely, endothelium-dependent relaxations by substance P were greater in the arteries with and without atherosclerosis from WHHL rabbits than in the arteries from JW rabbits. Endothelium-independent relaxations elicited by sodium nitroprusside and 2,2-(hydroxynitrosohydrazino)bis-ethanamine (NOC18) did not differ in the arteries from JW and WHHL rabbits. The responses to acetylcholine and substance P of JW rabbit arteries with the endothelium were not attenuated by treatment with pertussis toxin. L-NA-resistant, endothelium-dependent relaxations by substance P were almost abolished by charybdotoxin, and atherosclerosis did not alter the response. It is concluded that endothelial functions, evaluated by substance P, in rabbit carotid arteries are not impaired by atherosclerosis and by long exposure to hyperlipidemia in vivo. Dysfunction of muscarinic receptors may be involved in the depressed response to acetylcholine. As far as the arteries used in the present study are concerned, responses mediated possibly by endothelium-derived hyperpolarizing factor (EDHF) are unlikely to be modulated by atherosclerosis.

Acetylcholine↗
PubMed2000

Surface and flexoelectric polarization in a nematic liquid crystal directly measured by a pyroelectric technique

An alternative, pyroelectric effect based technique was developed for the direct measurement of the surface polarization in homogeneously and homeotropically oriented nematic cells as well as for the measurement of the flexoelectric polarization in hybrid aligned nematic cells. The pyroelectric response was measured with a modulated beam of a diode laser, absorbed by a dye incorporated in a standard liquid crystal 4-pentyl- 4(')-cyanobiphenyl. The dye provided a gradient of the temperature increment along the cell normal, which allowed for the separation of pyroelectric contributions from both the opposite surfaces and the bulk. The signs and absolute magnitude of the polarizations mentioned have been found over the entire temperature range of the nematic phase.

Journal Article↗
PubMed2000

[Meningococcemia associated with C7 deficiency].

We report a 20-year-old woman who developed meningococcemia. The patient developed fever, vomiting and skin rash, then was sent to our hospital for shock. Physical and laboratory examination revealed septic shock and DIC. Her blood culture grew Neisseria meningitidis (W135). She recovered promptly with PCG, gabexate mesilate and intensive care for shock. Hemolytic activities of the patient's complement were less than 12/CH50 during the course. Screening for each component of the complements suggested that this patient had deficiency of C7. Meningococcal disease has seldom seen in Japan. Early recognition is essential so that appropriate antibiotic therapy and supportive care can be promptly started because shock and death may ensure within hours after onset of symptoms.

Adult↗
PubMed2000

cGMP-independent inotropic effects of nitric oxide and peroxynitrite donors: potential role for nitrosylation.

Nitric oxide (NO) has concentration-dependent biphasic myocardial contractile effects. We tested the hypothesis, in isolated rat hearts, that NO cardiostimulation is primarily non-cGMP dependent. Infusion of 3-morpholinosydnonimine (SIN-1, 10(-5) M), which may participate in S-nitrosylation (S-NO) via peroxynitrite formation, increased the rate of left ventricular pressure rise (+dP/dt; 19 +/- 4%, P < 0.001, n = 11) without increasing effluent cGMP or cAMP. Superoxide dismutase (SOD; 150 U/ml) blocked SIN-1 cardiostimulation and led to cGMP elaboration. Sodium nitroprusside (10(-10)-10(-7) M), an iron nitrosyl compound, did not augment +dP/dt but increased cGMP approximately eightfold (P < 0.001), whereas diethylamine/NO (DEA/NO; 10(-7) M), a spontaneous NO. donor, increased +dP/dt (5 +/- 2%, P < 0.05, n = 6) without augmenting cGMP. SIN-1 and DEA/NO +dP/dt increase persisted despite guanylyl cyclase inhibition with 1H-(1,2,4)oxadiazolo-(4,3,-a)quinoxalin-1-one (10(-5) M, P < 0.05 for both donors), suggesting a cGMP-independent mechanism. Glutathione (5 x 10(-4) M, n = 15) prevented SIN-1 cardiostimulation, suggesting S-NO formation. SIN-1 also produced SOD-inhibitable cardiostimulation in vivo in mice. Thus peroxynitrite and NO donors can stimulate myocardial contractility independently of guanylyl cyclase activation, suggesting a role for S-NO reactions in NO/peroxynitrite-positive inotropic effects in intact hearts.

Animals↗
PubMed2000

Mechanisms of reduced nitric oxide/cGMP-mediated vasorelaxation in transgenic mice overexpressing endothelial nitric oxide synthase.

NO, constitutively produced by endothelial NO synthase (eNOS), plays a key regulatory role in vascular wall homeostasis. We generated transgenic (Tg) mice overexpressing eNOS in the endothelium and reported the presence of reduced NO-elicited relaxation. The purpose of this study was to clarify mechanisms of the reduced response to NO-mediated vasodilators in eNOS-Tg mice. Thoracic aortas of Tg and control mice were surgically isolated for vasomotor studies. Relaxations to acetylcholine and sodium nitroprusside were significantly reduced in Tg vessels compared with control vessels. Relaxations to atrial natriuretic peptide and 8-bromo-cGMP were also significantly reduced in Tg vessels. Reduced relaxations to these agents were restored by chronic N(G)-nitro-L-arginine methyl ester treatment. Basal cGMP levels of aortas were higher in Tg mice than in control mice, whereas soluble guanylate cyclase (sGC) activity in Tg vessels was approximately 50% of the activity in control vessels. Moreover, cGMP-dependent protein kinase (PKG) protein levels and PKG enzyme activity were decreased in Tg vessels. These observations indicate that chronic overexpression of eNOS in the endothelium resulted in resistance to the NO/cGMP-mediated vasodilators and that at least 2 distinct mechanisms might be involved: one is reduced sGC activity, and the other is a decrease in PKG protein levels. We reported for the first time that increased NO release from the endothelium reduces sGC and PKG activity in mice. These data may provide a new insight into the mechanisms of nitrate tolerance and cross tolerance to nitrovasodilators.

Animals↗
PubMed2000

Identification and functional analysis of mutations in the hepatocyte nuclear factor-1alpha gene in anti-islet autoantibody-negative Japanese patients with type 1 diabetes.

Mutations in the hepatocyte nuclear factor-1alpha (HNF-1alpha) gene are the cause of maturity-onset diabetes of the young type 3 (MODY 3), which is characterized by a severe impairment of insulin secretion and early onset of the disease. Although the majority of patients with type 1 diabetes have type 1A, immune-mediated diabetes, there is a significant percentage of the patients who have no evidence of an autoimmune disorder at the onset of disease. The aim of this study was to estimate the prevalence of MODY 3 in antiislet autoantibody negative patients with type 1 diabetes. From a large population-based sample of unrelated Japanese patients with type 1 diabetes, 28 patients who lacked autoantibodies to glutamic acid decarboxylase, islet cell antigen 512/insulinoma-associated antigen-2, phogrin (phosphate homolog of granules of insulinoma)/insulinoma-associated antigen-2beta, and insulin at the onset of type 1 diabetes were examined by PCR-based direct sequencing of the 10 exons, flanking introns, and the promoter region of the HNF-1alpha gene. Two (7.1%) of 28 autoantibody-negative patients with type 1 diabetes were identified as carrying mutations in the HNF-1alpha gene. One patient carried a frameshift mutation (Pro379fsdelCT) in exon 6, and another patient carried a novel 2-bp substitution at nucleotides +45 (G to A) and +46 (C to A) from the transcriptional site of the promoter region. These mutations were identified in heterozygous form and were not identified in 64 unrelated healthy control subjects or 54 unrelated islet autoantibody-positive patients with type 1 diabetes. Functional analysis of the mutant HNF-1alpha gene indicated that the Pro379fsdelCT mutation had no transcriptional trans-activation activity and acted in a dominant negative manner. The +45/46 GC to AA mutation in the promoter region showed reduced promoter activity by 10-20% compared to the wild-type sequence. In conclusion, about 7% of Japanese diabetic patients lacking antiislet autoantibodies initially classified as having type 1 diabetes could have diabetes caused by mutations in the HNF-1alpha gene.

Adolescent↗
PubMed2000

Characteristics of post-tetanic contraction induced by naloxone in guinea pig ileum.

The characteristics of isolated guinea-pig ileal contractions of basal tension after tetanic stimulation in the presence of a high concentration of naloxone (NLX) [post-tetanic contraction] were investigated. The post-tetanic contraction did not occur in the absence of NLX, but did occur in a concentration-dependent manner in the presence of a high concentration of NLX (5 x 10(-7), 10(-6), 10(-5) and 5 x 10(-5) M), the concentration of which was higher than that required for antagonizing post-tetanic twitch inhibition. The contraction in the presence of 10(-6) M NLX was diminished by washing NLX from the preparation with Krebs-bicarbonate solution. The contraction under 10(-6) M NLX occurred in a frequency-dependent manner (5, 10 and 20 Hz), but not at 0.1 Hz. Tetanic stimulation (5, 10 and 20 Hz) without NLX did not induce this contraction. The post-tetanic contraction with 10(-6) M NLX had a tendency to be antagonized in the presence of 5 x 10(-6) M atropine. Methysergide (5 x 10(-5) M) had no effect on this contraction. Spantide (10(-5) M) largely inhibited the contraction, and indomethacin (5 x 10(-6) M) and tetrodotoxin (5 x 10(-7) M) completely inhibited this contraction. These results indicate that tetanic stimulation in the presence of a high concentration of NLX induces contraction of the ileal muscle due to the release of endogenous ileal contractile substances (substance P, prostaglandins and acetylcholine), and suggests that these contractions are closely linked to the endogenous opioid system induced by tetanic stimulation in the ileum.

Acetylcholine↗