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Biomedical subjects

K Hatta

Publications and source records attributed to K Hatta.

At least 19 recordsLinked to original sources
PubMed2003

Blood endothelin-1 and cold-induced vasodilation in patients with primary Raynauld's phenomenon and workers with vibration-induced white finger.

AIM: Cold water-immersion induces vasoconstriction with an elevation of blood endothelin-1, which is a potent vasoconstrictor peptide, in patients with primary Raynaud's phenomenon (PRP). However, physiological involvement of endothelin-1 in cold-induced vasodilation (CIVD) remains to be elucidated. METHODS: We monitored changes of finger blood flow during cold water (10 degrees C) immersion and assayed blood endothelin-1 in 7 PRP patients and 7 workers with vibration-induced white finger (VWF) and in the respective control subjects. RESULTS: While significant reductions in finger blood flow at 2 min after the immersion were observed in PRP patients and VWF workers, its elevation at 4 min, which was considered to reflect CIVD, was recognized only in PRP patients. In healthy controls, blood endothelin-1 increased at 4 min and returned to the basal level immediately after the immersion. The increase in blood endothelin-1 at 4 min in PRP patients was greater than that in controls, and continued even after the immersion. Conversely, the increase neither at 4 min nor after immersion was seen in VWF workers. Local vascular changes produced by repetitive vibration may be responsible for the attenuated CIVD and unchanged blood endothelin-1 during cold water-immersion in VWF workers. CONCLUSION: Our results showing elevated blood endothelin-1 during and after immersion in PRP contrast with that in VWF suggesting that endothelin-1 is related to sympathetic hyperactivity which is more involved in PRP rather than VWF. It seems unlikely that endothelin-1 is functionally or directly associated with CIVD.

Adult↗
PubMed2001

Involvement of central, but not placental corticotropin releasing hormone (CRH) in heat stress induced immunosuppression during pregnancy.

To clarify whether corticotropin releasing hormone (CRH) and beta-endorphin (betaEP) system mediate maternal immunosuppression in pregnant rats exposed to heat through central or placental pathway, we examined the effects of intravenous (iv) (100 or 500 microg) or intracerebroventricular (icv) (5 microg) administration of CRH receptor antagonist alpha-helical CRH (9-41) on splenic natural killer cell activity (NKCA) as well as betaEP in blood, pituitary lobes, and placenta in pregnant rats at 15 to 16 days gestation. Two-way ANOVA revealed that heat reduced NKCA and elevated blood and pituitary betaEP but did not change placental betaEP. Iv administered 500 microg and icv administered alpha-helical CRH reversed the reduced NKCA and the elevated pituitary betaEP, while iv administration of 100 microg alpha-helical CRH did not. The increased blood betaEP was reversed by iv 100 and 500 microg alpha-helical CRH and icv administration. Both iv and icv administrations reduced placental betaEP independent of heat exposure. Thus, the response of placental betaEP to iv administration of alpha-helical CRH seemed to be stronger than that of pituitary betaEP. These results indicate that alpha-helical CRH which acts on pituitary betaEP antagonizes heat-induced immunosuppression during pregnancy, suggesting that immunosuppression produced by heat stress during pregnancy is mediated by the central CRH system. The placental CRH-betaEP system seems unlikely to be involved in the immunosuppression. Physiologic roles of placental CRH and opioid system should be clarified by future in vitro experiments using placenta specimen including placental immunocyte.

Animals↗
PubMed2001

Slow inhibitory potentials in the teleost Mauthner cell.

In vivo recordings from Mauthner cells in adult zebrafish (Danio rerio) and goldfish (Carassius auratus) preparations with potassium chloride filled electrodes revealed a new class of long-lasting synaptic events in these cells. Their decay time constant ranged from 20 to 80ms, which is about 20 times longer than that of previously identified fast glycinergic inhibitory postsynaptic potentials in this neuron. The average time to peak of these slow events ranged from 1 to 6ms. We demonstrated that they are also inhibitory since (i) they were resistant to antagonists of the excitatory glutamatergic receptors; (ii) their amplitude was increased following chloride loading of the Mauthner cell; (iii) their reversal potential was the same as that of fast, glycinergic inhibitory postsynaptic potentials; and (iv) they produced an inhibitory shunt of the cell's membrane resistance. Furthermore, as with the fast inhibitory postsynaptic potentials, the decay time of the slow events is voltage dependent, increasing when the Mauthner cell is depolarized. However, these inhibitory postsynaptic potentials had a different pharmacological profile to the fast glycinergic ones. That is, they persisted in the presence of strychnine at doses that abolished the fast ones and they were more sensitive to bicuculline. These data are compatible with the notion that these inhibitory postsynaptic potentials are mediated by activation of a different inhibitory receptor type, and may be GABAergic. In addition, the decay time constant of the fast inhibitory postsynaptic current was shorter than the first of the two components that contribute to the bi-exponential decay reported previously for miniature inhibitory postsynaptic currents in Mauthner cells of larval zebrafish. This suggests developmental modifications and/or a switch in the assembly of glycine receptor subtypes. While amplitude distributions of the fast miniature inhibitory postsynaptic potentials recorded in the presence of tetrodotoxin generally could fit with a single Gaussian function, the amplitude histograms of slow miniature events were skewed, often with multiple nearly equally spaced peaks, consistent with the synchronous release of several quantal units. These previously undescribed slow unitary inhibitory postsynaptic potentials contribute to inhibitory synaptic noise recorded in the Mauthner cells. Specifically, autocorrelation analysis revealed gamma-like rhythms (30-80Hz) in each of two phases, characterized as "noisy" and "quiet", and dominated by the fast and slow inhibitory postsynaptic potentials, respectively. The major frequencies of these two states were significantly different (i.e. around 90 and 40Hz, respectively), suggesting that the fast and slow inhibitory postsynaptic potentials are derived from different inhibitory networks. Chloride-filled Mauthner cells gradually hyperpolarized in the presence of tetrodotoxin, reflecting the effect of ongoing activity in the interneurons that produce the slow events. We conclude that this new class of inhibitory postsynaptic potentials contributes to the tonic inhibition which controls the Mauthner cell's excitability. In physiological conditions, this regulatory influence is expressed as a continuous shunt of this neuron's input resistance and responsiveness to sensory inputs.

2-Amino-5-phosphonovalerate↗
PubMed2001

The association between intravenous haloperidol and prolonged QT interval.

Although intravenous haloperidol (HAL) is an effective medication that is often prescribed to treat agitation, several instances of torsade de pointes or prolonged QT interval have been reported. To investigate the association between intravenous HAL and QT prolongation and between intravenous HAL and ventricular tachyarrhythmia, a cross-sectional cohort study was performed that included measuring corrected QT intervals (QTc) on an emergency basis before intravenous HAL and continuously monitoring electrocardiographic (ECG) findings after intravenous HAL. During a 2-month period, 47 patients received intravenous injections to control psychotic disruptive behavior. According to clinical practice, patients were divided as follows. The FZ-alone group was treated with intravenous flunitrazepam (FZ), and the FZ-plus-HAL group received intravenous FZ followed by intravenous HAL. Although the difference in the mean QTc immediately after intravenous FZ between the two groups was not significant, the mean QTc after 8 hours in the FZ-plus-HAL group was longer than that in the FZ-alone group (p < 0.001). Four patients in the FZ-plus-HAL group had a QTc of more than 500 msec after 8 hours. The change in QTc during 8 hours significantly differed between the two groups (t = 2.64, p > 0.05). Furthermore, the change in QTc was moderately correlated with the dose of intravenous HAL, as evidenced by a coefficient of correlation of 0.48 (p < 0.001). However, ventricular tachyarrhythmia was not detected among 307 patients within a 1-year period, although the ECG was continuously monitored for at least 8 hours after intravenous HAL. The modest nature of QTc prolongation and the apparent absence of ventricular tachyarrhythmia under continuous ECG monitoring indicate that QTc prolongation associated with intravenous HAL is not necessarily dangerous. However, in an emergency situation, clinicians cannot exclude patients predisposed to torsade de pointes, such as those with inherited ion channel disorders. Therefore, clinicians should be aware of the association between intravenous HAL and QT prolongation.

Adult↗
PubMed2001

Significantly rapid relief from steroid-resistant nephrotic syndrome by LDL apheresis compared with steroid monotherapy.

Rapid amelioration of hypercholesterolemia by LDL apheresis (LDL-A) was performed for long-standing nephrotic syndrome (NS) with hyperlipidemia due to focal segmental glomerulosclerosis (FGS) and the clinical data and prognosis were compared between LDL-A-treated and nontreated groups. Seventeen steroid-resistant NS patients treated with LDL-A (LDL-A group) and 10 NS patients treated with steroids only (steroid-monotherapy (SM) group) were compared. Serum cholesterol and phospholipid levels were significantly lowered only in the LDL-A group (p < 0.01, respectively). The LDL-A group showed a significant decrease of urinary protein (UP, p < 0.01) and increase of serum albumin (p < 0.05). Average time needed to achieve a decrease of UP to less than nephrotic range (< 3.5 g/day) was significantly shorter in the LDL-A group than in the SM group (p < 0.01). Although this is not a prospective study, it is highly expected that a rapid improvement of hypercholesterolemia by LDL-A in steroid-resistant NS will provide more rapid relief from NS than steroid therapy alone.

Adolescent↗
PubMed2000

Prolonged QT interval in acute psychotic patients.

Some recent clinical studies indicate that hypokalemia is characteristic for acute psychotic patients at the time of emergency admission. As hypokalemia is one of the major causes for prolonged QT interval, it was hypothesized that acute psychotic patients could show prolonged QT interval. Sixty-seven drug-free, acute psychotic patients were evaluated for corrected QT (QTc) interval, as well as demographic and clinical characteristics at the time of emergency admission. The mean QTc interval of psychiatric emergency patients was prolonged, and the mean QTc interval of psychiatric emergency patients was longer than that of psychiatric outpatients (t=5.20, P<0.0001). Age- or gender-related difference, circadian fluctuation of QT interval, medication, concomitant disease, obesity, and serum electrolytes except potassium were not major causes. There was a significant negative correlation as evidenced by a coefficient of correlation of -0.28 (P<0.05). As psychiatric emergency patients often receive parenteral antipsychotics, which may have adverse effects on prolonged QT interval, paying attention to QT interval might have some clinical significance on emergency admission.

Acute Disease↗
PubMed2000

[A case of subclinical Sjögren syndrome associated with high levels of serum IgM, thrombocytopenia and splenomegaly].

A 13-years-old girl was admitted to our hospital with high levels of serum IgM, thrombocytopenia and splenomegaly. Not only IgG but also IgM were found on the surface of platelets by flow-cytometry. Direct Coombs' test was positive, and IgG was also found on the surface of red blood cells. After splenectomy, platelet count was increased and serum IgM was decreased. The biopsy of salivary glands showed infiltration of lymphocytes around the ducts, and Shirmer test revealed slightly decreased secretion of tears, suggesting subclinical Sjögren syndrome.

Adolescent↗
PubMed1999

Tonic inhibition alternates in paired neurons that set direction of fish escape reaction.

Crossed antagonism between activities in neurons subserving alternating movements such as swimming or walking has been described in a number of systems. The role of reciprocal inhibition has been implicated in these activities, but involvement of rhythmic ongoing fluctuations of membrane potential, called synaptic "noise," has not been examined. In the Mauthner (M) cells, which control the direction of escape, this activity is inhibitory. We report that in the zebrafish (Danio rerio), inhibitory synaptic noise exhibits prolonged bursts of rhythmic, inhibitory postsynaptic potentials, which attenuate the M cell's sensibility to excitatory sensory drives. Furthermore, paired intracellular recordings have shown that inhibitory synaptic noise alternates between two distinct states, noisy and quiet, which are out of phase in the two cells. Firing of either M cell resets this pattern by reducing the inhibition in the contralateral one. This suggests that an avoidance reflex in one direction may favor initiation, by the opposite M cell, of a subsequent escape toward a more appropriate location.

Action Potentials↗
PubMed1999

Hypokalemia and agitation in acute psychotic patients.

Hypokalemia is caused partly by intensive exercise. Some evidence suggests that psychological distress may cause hypokalemia. The relationship between the decline of serum potassium concentration and the level of symptoms of acute agitation, which was defined as a total score on a subset of six categories on the 18-item Brief Psychiatric Rating Scale (anxiety, tension, mannerism and posturing, hostility, uncooperativeness, psychomotor excitement), was examined in 313 schizophrenic men, admitted on an emergency basis during a 24-month period. In addition, change in serum potassium concentration after sedation was investigated. Serum potassium concentration in the severely agitated group was lower than that in the mild group. There was a significant correlation between serum potassium concentration and the level of symptoms of acute agitation (r = -0.30, P < 0.0001). Although the decline of serum potassium concentration in the patients who were sufficiently sedated improved within 8 h, that in the patients showing high scores on the acute agitation subset even 8 h after emergency admission was prolonged. Results indicate that sedation improves acute agitation-induced hypokalemia. rights

Acute Disease↗
PubMed1999

Low density lipoprotein apheresis therapy for steroid-resistant nephrotic syndrome. Kansai-FGS-Apheresis Treatment (K-FLAT) Study Group.

BACKGROUND: The pathogenic role of hyperlipidemia in long-standing nephrotic syndrome (NS) is known to be responsible for both the progression of glomerulosclerosis and tubulointerstitial injury, especially in focal segmental glomerulosclerosis (FGS). METHODS: Aggressive lipid lowering treatment by low density lipoprotein (LDL) apheresis (LDL-A) using a dextran sulfate cellulose column to treat patients with steroid-resistant or frequently recurrent severe NS was performed first without fixing the protocol in eight patients with FGS and one with minimal change nephrotic syndrome (MCNS). The period of NS before LDL-A, number and average intervals of LDL-A until the end of the therapy, and the prognosis were investigated. Next, a multicenter study with a fixed protocol of LDL-A treatment was designed in combination with steroid therapy for treatment twice a week for three weeks and weekly for six weeks, and was performed in 17 patients with FGS. The effects on the state of NS in addition to the change of urinary eicosanoid metabolites and remission rates were evaluated. RESULTS: In the preliminary study, along with a rapid improvement of hyperlipidemia, a high incidence of remission was achieved by LDL-A performed at relatively short intervals. In the multicenter study with a fixed protocol, there was a significant decrease of urinary protein (P < 0.001) and increase of serum albumin (P < 0.02) as well as a decrease of thromboxane B2 (TXB2) excretion (P < 0.05) after the treatment. Urinary excretion of TXB2 was significantly reduced after LDL-A (P < 0.05). The rate of entering into complete or incomplete remission was 71% with a relatively short duration of nephrotic-range proteinuria using the LDL-A therapy in comparison with steroid therapy alone. CONCLUSION: The rapid improvement of hypercholesterolemia with LDL-A treatment may provide a new approach for a high rate of improvement in the degree of NS in steroid-resistant NS of FGS and MCNS.

Adolescent↗
PubMed1999

The predictive value of benzodiazepine tolerance in persistently aggressive schizophrenia.

The aim of this study was to determine whether benzodiazepine tolerance might provide a predictive marker for persistent aggression in schizophrenia. Seventy-seven male schizophrenic patients newly admitted to our psychiatric intensive care unit due to violent behavior during a 4-month period were examined. As a result, a high dose of benzodiazepine required for sedation or a short duration until regaining consciousness after the initial sedation, was related to severer aggression on waking up after sedation. Despite the small number of subjects examined, a conservative claim can be made that the level of the effect of benzodiazepine required for sedation seems to predict persistent severe aggression in schizophrenia.

Adolescent↗
PubMed1998

Physiological properties of the Mauthner system in the adult zebrafish.

We investigated the morphological and electrophysiological properties of the Mauthner (M-) cell and its networks in the adult zebrafish (Danio rerio) in comparison with those in the goldfish (Carassius auratus). The zebrafish M-cell has an axon cap, a high resistivity structure which surrounds the initial segment of the M-axon, and accounts for an unusual amplification of the fields generated within and around it. Second, extra- and intracellular recordings were performed with microelectrodes. The resting potential was approximately -80 mV with an input resistance of approximately 0.42 M omega. The M-cell extracellular field was large (10-20 mV), close to the axon hillock, and the latency of antidromic spikes short (approximately 0.4 milliseconds), confirming a high conduction velocity in the M-axon. The extrinsic hyperpolarizing potential (EHP), which signals firing of presynaptic cells and collateral inhibition, was markedly lower at frequencies of spinal stimulation > approximately 5/second, suggesting an organization of the recurrent collateral network similar to that in the goldfish. Inhibitory postsynaptic potentials (IPSPs) were highly voltage-dependent; their decay time constant was increased by depolarizations. The presynaptic neurons which are numerous could be identified by their passive hyperpolarizing potential (PHP) produced by the M-spike current. Auditory responses, mediated via mixed synapses (electrical and chemical), had short delays and hence are well suited to trigger the escape reaction. The similarities of their properties indicate that the wealth of information generated over decades in the goldfish can be extrapolated to the zebrafish.

Animals↗
PubMed1998

Natural killer cell activity reduced by microwave exposure during pregnancy is mediated by opioid systems.

We have previously demonstrated immunosuppression including reduced splenic natural killer cell activity (NKCA) in pregnant rats exposed to microwaves produced mainly by their thermal action. To examine the involvement of opioid systems in reduced NKCA in pregnant rats exposed to microwaves at a relatively low level (2 mW/cm2 incident power density at 2450 MHz for 90 min), we assayed beta-endorphin (betaEP) in blood, pituitary lobes, and placenta as well as splenic NKCA in virgin and/or pregnant rats. Although microwaves elevated colonic temperatures by 0.8 degreesC for virgin and 0.9 degreesC for pregnant rats, and betaEP in blood and anterior pituitary lobes (AP) significantly, it did not change blood corticosterone as an index of hypothalamic-pituitary adrenal axis. There were significant interactions between pregnancy and microwave exposure on splenic NKCA, betaEP in both blood and AP, and blood progesterone. Intra-peritoneal administration of opioid receptor antagonist naloxone prior to microwave exposure increased NKCA, blood, and placental betaEP in pregnant rats. Alterations in splenic NKCA, betaEP and progesterone in pregnant rats exposed to microwaves may be due to both thermal and nonthermal actions. These results suggest that NKCA reduced by microwaves during pregnancy is mediated by the pituitary opioid system.

Animals↗
PubMed1998

Abnormal physiological conditions in acute schizophrenic patients on emergency admission: dehydration, hypokalemia, leukocytosis and elevated serum muscle enzymes.

This study investigated varieties and incidence of abnormal physiological conditions in acute schizophrenic patients on emergency. Laboratory data obtained prior to treatment from patients, admitted on an emergency basis during an 18-month period, were evaluated retrospectively, as well as demographics and clinical characteristics. Of 259 male acute schizophrenic patients (ICD-10: F2), 6.9% revealed dehydration, a third had hypokalemia and leukocytosis, and two thirds showed elevated serum muscle enzymes. These percentages were statistically significant compared with those of outpatients. In addition, the former three of these conditions in the F2 group were as frequent as those in alcohol and/or psychoactive substance abusers (ICD-10: F1) on emergency admission, although elevated serum muscle enzymes in the F2 group was less frequent than that in the F1 group. In order to prevent these abnormal physiological conditions from worsening and becoming life-threatening, one fourth of the F2 group [dehydration, 6.9%, severe hypokalemia (< 3.0 mEq/l), 2.3%, and markedly elevated serum muscle enzymes (creatine phosphokinase > 1000 IU/l), 16.5%] required medical management such as fluid therapy and various types of monitoring. In cases of a behavioral emergency, laboratory screening and monitoring of urinary output were essential. Due to their lack of cooperation, case history, physical examination, and initial vital signs did not contribute to detection of their medical condition.

Acute Disease↗
PubMed1998

Central administration of interleukin-1 beta reduces natural killer cell activity in non-pregnant rats, but not in pregnant rats.

To examine responses of natural killer cell activity (NKCA) to interleukin-1 beta (IL-1 beta) during pregnancy, we determined splenic NKCA as well as blood and brain indicators in virgin and pregnant rats (14 or 21 days gestation) with intracerebroventricular (i.c.v.) administration of IL-1 beta. NKCA was reduced and blood beta-endorphin (beta EP) was increased with the progress of pregnancy. I.c.v. administration of IL-1 beta reduced NKCA and corticotropin-releasing hormone (CRH) in the median eminence (ME), and increased beta EP in virgin rats, but did not change any parameters in pregnant rats with 21 days gestation. These data suggest that the immunosuppressive effect of central administration of IL-1 beta is blocked by pregnancy. CRH in the ME and opioid system seem to be involved in the inhibitory effect of pregnancy on IL-1 beta-induced immunosuppression.

Animals↗
PubMed1998

A risk for obstruction of the airways in the parenteral use of levomepromazine with benzodiazepine.

Arrhythmogenic effects of phenothiazines appear to be associated with sudden death, whereas respiratory complications have received little attention. In this report we describe 5 cases with accompanying obstruction of the airways after intramuscular injections of levomepromazine (LPZ), a potent sedative phenothiazine, in combination with intravenous injections of benzodiazepine (BZ) during a 3-month period in a psychiatric intensive care unit. Two out of 5 cases were unpredictable because obstruction of the airways occurred 2 hours or more after the last injection. As compared with patients who received parenteral (intravenous or intramuscular) injections during the same period, the dose of intramuscular LPZ was significantly large in the 5 cases with obstruction of the airways. All 5 of these cases received intramuscular LPZ 0.52 mg/kg or more. In contrast, there was no patient with obstruction of the airways who received only intramuscular LPZ, the combination of LPZ and HDL, or BZ and HDL. The occurrence of obstruction of the airways among patients who received both intramuscular LPZ and intravenous BZ was significantly higher than among patients who received other drug regimes. These preliminary results suggest that the intramuscular use of LPZ with intravenous BZ may be a risk for obstruction of the airways.

Adult↗