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Biomedical subjects

H Iwashita

Publications and source records attributed to H Iwashita.

At least 19 recordsLinked to original sources
PubMed2004

In vivo transfer of a neuronal nitric oxide synthase expression vector into the rat bladder by electroporation.

OBJECTIVE: To investigate the possibility of in vivo gene transfer by attempting to transfer the neuronal nitric oxide synthase (nNOS) gene into rat bladder using electroporation. MATERIALS AND METHODS: The bladder was exposed through an abdominal midline incision in 8-week-old male rats. Plasmid DNA of the marker genes green fluorescent protein (GFP) and luciferase, and the nNOS gene, was then injected into the subserosal space of the bladder and electroporation applied. At 72 h after gene transfer, GFP and luciferase were assayed in the isolated bladder and immunohistochemical staining used to detect nNOS; NO(x) released from isolated bladder strips was also assessed using microdialysis and high-performance liquid chromatography. RESULTS: From the luciferase assay, 45 V, 1 Hz, 50 ms and eight pulses were selected as the optimum conditions for electroporation. Bladder specimens with GFP genes injected by electroporation showed bright and numerous sites of GFP expression in the smooth muscle layer. In rats with the nNOS gene injected by electroporation there was marked nNOS immunoreactivity, and NO(x) released from bladder strips was significantly greater than in the control groups. CONCLUSIONS: These results suggest that electroporation is a useful technique for in vivo gene transfer into rat bladder smooth muscles, and that the nNOS gene transferred by this procedure functionally expresses and contributes to NO production.

Animals↗
PubMed2001

Role of gob-5 in mucus overproduction and airway hyperresponsiveness in asthma.

Airway hyperresponsiveness (AHR), goblet cell metaplasia, and mucus overproduction are important features of bronchial asthma. To elucidate the molecular mechanisms behind these pulmonary pathologies, we examined for genes preferentially expressed in the lungs of a murine model of allergic asthma by using suppression subtractive hybridization (SSH). We identified a gene called gob-5 that had a selective expression pattern in the airway epithelium with AHR. Here, we show that gob-5, a member of the calcium-activated chloride channel family, is a key molecule in the induction of murine asthma. Intratracheal administration of adenovirus-expressing antisense gob-5 RNA into AHR-model mice efficiently suppressed the asthma phenotype, including AHR and mucus overproduction. In contrast, overexpression of gob-5 in airway epithelia by using an adenoviral vector exacerbated the asthma phenotype. Introduction of either gob-5 or hCLCA1, the human counterpart of gob-5, into the human mucoepidermoid cell line NCI-H292 induced mucus production as well as MUC5AC expression. Our results indicated that gob-5 may play a critical role in murine asthma, and its human counterpart hCLCA1 is therefore a potential target for asthma therapy.

Animals↗
PubMed1998

Hypoxemia decreases the shivering threshold in rabbits anesthetized with 0.2 minimum alveolar anesthetic concentration isoflurane.

UNLABELLED: Shivering has been proposed as an etiology of postoperative hypoxemia. The difficulty with this theory is that hypoxemia inhibits shivering in unanesthetized cats, rats, and humans. However, anesthesia inhibits many protective reflexes, including the ventilatory response to hypoxemia. We therefore tested the hypothesis that arterial hypoxemia fails to inhibit shivering in lightly anesthetized rabbits. Rabbits were intubated and instrumented during exposure to surgical concentrations of anesthesia, and anesthesia was then maintained with 0.2 minimum alveolar anesthetic concentration isoflurane. The core was cooled at a rate of 2-3 degrees C/h by perfusing water at 10 degrees C through a colonic thermode. Core temperatures were recorded from the distal esophagus. Sustained, vigorous shivering was considered physiologically significant. The core temperature that triggering significant shivering identified the thermoregulatory threshold for this response. Arterial blood was sampled for gas analysis at the shivering threshold in each rabbit. Hypoxemia linearly reduced the shivering threshold from 36.7 degrees C at 130 mm Hg to 35.4 degrees C at 50 mm Hg (threshold = PaO2.0.019 + 34.3; r2 = 0.49). We failed to confirm our hypothesis: instead, even mild hypoxemia reduced the shivering threshold >1 C. A 1 C decrease in the shivering threshold is likely to prevent or stop most postoperative shivering because it exceeds the reduction produced by many effective anti-shivering drugs. These data do not support the theory that shivering causes postoperative hypoxemia. IMPLICATIONS: Shivering has been proposed as an etiology of postoperative hypoxemia. Our data, in contrast, show that mild hypoxemia inhibits shivering. Shivering is thus unlikely to be a cause of postoperative hypoxemia.

Anesthesia, Inhalation↗
PubMed1997

Comparison of distal oesophageal temperature with "deep" and tracheal temperatures.

PURPOSE: To compare distal oesophageal (reference) temperature with "deep-sternal," "deep-forehead," and tracheal temperatures, establishing the accuracy and precision of each. METHODS: We studied 20 patients undergoing general anaesthesia for gynaecological surgery. Their lungs were mechanically ventilated with a circle system, at a fresh-gas flow rate of 6 L.min-1 Respiratory gases were not warmed or humidified. Tracheal temperatures were recorded from a Trachelon tube inserted approximately 21 cm. Deep-body temperatures were measured at the sternum and forehead using a Coretemp thermometer. The principle of the method is to null thermal flux through a cutaneous disk, thus obliterating thermal gradients between the sides of the disk, skin surface, and subcutaneous tissues. Distal oesophageal temperatures were measured from thermocouples incorporated into oesophageal stethoscopes. Tracheal and deep-tissue temperatures were compared with oesophageal temperature using regression and Bland and Altman analyses. RESULTS: Tracheal, sternal, and forehead temperatures correlated similarly with distal oesophageal temperature, correlation coefficients (r2) being 0.7 in each case. The offset (oesophageal temperature minus study site) was considerably larger for tracheal temperature (0.7 degree C) than for the other sites (0.2 degree C). However, the precision was only 0.3 degree C at each site. CONCLUSION: Our data suggest that tracheal temperatures may not be an adequate substitute for conventional core-temperature monitoring sites. In contrast, the accuracy and precision of deep-tissue temperature monitoring at the sternum and forehead was sufficient for clinical use.

Anesthesia, General↗
PubMed1997

I.m. midazolam as premedication produces a concentration-dependent decrease in core temperature in male volunteers.

We tested the hypothesis that premedication with i.m. midazolam decreases core temperature dose-dependently. We studied six male volunteers, in random order, on 3 days: (1) no midazolam administration (control day), (2) midazolam 0.025 mg kg-1 i.m., (3) midazolam 0.075 mg kg-1 i.m. On the first day, subjects were maintained alert during a 30-min control period. On the second and third days, midazolam 0.025 or 0.075 mg kg-1 was administered i.m. Core temperatures were measured at the right tympanic membrane. Four adhesive skin surface probes were fixed on the chest, upper right arm, lateral calf and thigh. Finger tip perfusion was evaluated using forearm minus fingertip and calf minus toe, skin surface temperature gradients. Thirty minutes after midazolam i.m., the level of sedation in the volunteers was assessed. Peripheral venous blood was obtained immediately after the assessment of the level of sedation. Tympanic membrane temperatures after administration of midazolam 0.075 mg kg-1 i.m. were significantly lower than those on the control and midazolam 0.025 mg kg-1 i.m. days at 20 and 30 min. The decreases in tympanic membrane temperatures at 30 min after midazolam i.m. became larger as the volunteers were more deeply sedated. i.m. midazolam produced a concentration-dependent decrease in tympanic membrane temperature at 30 min after midazolam 0.025 and 0.075 mg kg-1 i.m. We conclude that midazolam impaired tonic thermoregulatory vasoconstriction, allowing core-to-peripheral heat redistribution in a dose-dependent manner after i.m. administration.

Adult↗
PubMed1997

Analysis of the stabilization of hen lysozyme by helix macrodipole and charged side chain interaction.

In the N-terminal region of the alpha-helix of the c-type lysozymes, two Asx residues exist at the 18th and 27th positions. Hen lysozyme has Asp18/Asn27 (18D/27N), and we prepared three mutant lysozymes, Asn18/Asn27 (18N/27N), Asn18/Asp27 (18N/27D), and Asp18/Asp27 (18D/27D). The stability of the wild-type (18D/27N) lysozyme supported the existence of a hydrogen bond between the side chain of Asp18 and the amide group at the N1 position in the alpha-helix, while the stability of the 18N/27D lysozyme supported the presence of the capping box between the Ser24 (N-cap) and Asp27 residues. Although electrostatic repulsion was observed between Asp18 and Asp27 residues in 18D/27D lysozyme, the dissociation of each residue contributed to stabilizing the B-helix in 18D/27D lysozyme through hydrogen bonding and charge-helix macrodipole interaction. This is the first evidence that two neighboring negative charges at the N-terminus of the helix both increased the stability of the protein.

Amino Acid Sequence↗
PubMed1996

A comparison of four infrared tympanic thermometers with tympanic membrane temperatures measured by thermocouples.

PURPOSE: To compare measurements made with four infrared tympanic thermometers (Genius, Thermopit, Quickthermo, and Thermoscan) with those recorded from thermocouples positioned in the contralateral ear. METHODS: Four tympanic thermometers were evaluated in 50 healthy volunteers (12 female and 38 male). Temperatures were measured, in random order, at the right tympanic membrane four times and the highest temperature was considered to be the true value measured by each thermometer. The control temperature was measured at the left tympanic membrane using Mon-a-Therm thermocouples. RESULTS: The tympanic membrane temperature measured by Genius correlated best with the Mon-a-therm measurement (TM) (r = 0.74). The tympanic membrane temperatures measured by Thermopit, Quickthermo, and Thermoscan correlated moderately with TM (r = 0.56, 0.63, and 0.58, respectively). Mean differences between TM and each temperature (TG, TTP, TQ, and TTS) were -0.3, 0.73, 0.42, and -0.3 degrees C, respectively. Likewise standard deviations were 0.33, 0.37, 0.35, and 0.35. CONCLUSION: We conclude that all but the Thermopit (TTP) are similarly useful for the management of patients during anaesthesia.

Adult↗
PubMed1996

Decreased cerebrospinal fluid levels of substance P in Machado-Joseph disease.

To clarify the mechanism of brain impairment in Machado-Joseph disease (MJD), we measured the cerebrospinal fluid (CSF) levels of substance P in 7 patients (mean age 45.7 +/- 12.09 years) with this disease. Four patients had type I and three had type II disease. Findings were compared with those obtained in 14 age-matched controls, 8 patients with Parkinson's disease, 7 patients with multiple system atrophy, and 6 patients with myopathy. The CSF level of substance P was significantly (p = 0.0000) lower in the patients with MJD, being 44.5% of the control value. However, the mean CSF levels of substance P in the patients with Parkinson's disease, multiple system atrophy, or myopathy did not differ significantly from that in the control subjects. The alteration in the CSF level of substance P may be related to the neurological impairment observed in MJD.

Adult↗
PubMed1996

Stabilization of lysozyme by introducing N-glycosylation signal sequence.

We designed mutant lysozymes with N-glycosylation signal sequences (Asn48-Gly49-Thr-50 and Asn87-Ile88-Thr89) by substituting Asp to Asn at positions 48 and 87. When these mutant lysozymes were expressed by using yeast (Saccharomyces cerevisiae) in Burkholder minimum medium, N-glycosylation occurred in both lysozymes. The mutant lysozyme with the oligosaccharide at Asn87 showed a similar character to a reported polymannosyl lysozyme [Nakamura, Takasaki, Kobayashi, and Kato (1993) J. Biol. Chem. 268, 12706-12712; Kato, Takasaki, and Ban (1994) FEBS Lett. 355, 76-80]. As judged from the thermodynamic stabilities of the lysozymes obtained by the guanidine hydrochloride denaturation method, the oligosaccharide-bearing mutant lysozymes were more stable by 0.4-1.6 kcal/mol than the corresponding unglycosylated lysozymes. Therefore, it is suggested that the introduction of an N-glycosylation signal sequence into a protein is an effective means to increase the stability of the protein.

Amino Acid Sequence↗
PubMed1996

Elevated cerebrospinal fluid lactate/pyruvate ratio in Machado-Joseph disease.

To identify the metabolic alterations related to mitochondrial functions in Machado-Joseph disease (MJD), we analyzed the cerebrospinal fluid (CSF) levels of lactate, pyruvate, and citric acid cycle intermediates by high performance liquid chromatography (HPLC) in 7 Japanese patients with that disease and then measured some mitochondrial enzymes. Their mean age was 46 years. Diseased controls were matched by age to the patients studied. The CSF level of lactate was significantly elevated, pyruvate was significantly decreased, and the lactate/pyruvate (L/P) ratio was significantly elevated in the patients with MJD. There were no significant differences of citric acid cycle intermediates of the CSF between the patients and the controls. We measured the native and dichloroacetate (DCA)-activated pyruvate dehydrogenase complex (PDHC) activities, and mitochondrial electron transport activities in 3 patients with MJD, and found these activities to be normal. Therefore, the increased CSF lactate, increased lactate/pyruvate ratio, and decreased pyruvate may reflect the decreased regional cerebral blood flow rather than metabolic derangement of the mitochondria.

Adult↗
PubMed1995

Sulfamethoxazole-trimethoprim double-blind, placebo-controlled, crossover trial in Machado-Joseph disease: sulfamethoxazole-trimethoprim increases cerebrospinal fluid level of biopterin.

We performed a double-blind, placebo-controlled, crossover trial of sulfamethoxazole-trimethoprim (S-T) in 8 patients with Machado-Joseph disease (MJD), and measured the blood and cerebrospinal fluid levels of biopterins, biogenic amines or metabolites, and folate. The clinical results were as follows; mild improvements of hyperreflexia of knee jerks and of rigospasticity of the legs during S-T treatment period. In addition, S-T significantly reduced the times of 8 motor activities on the timed tests. The biochemical results showed that basal levels of all biopterins and homovanillic acid in the cerebrospinal fluid (CSF) were reduced to less than half the levels of those of controls with other neurological diseases. After S-T treatment, total and oxidized form of biopterins in the CSF increased significantly. Therefore, S-T may be effective to neurologic deficits through its mechanism of increasing the level of brain biopterins.

Adult↗
PubMed1995

Effect of salt concentration on the pKa of acidic residues in lysozyme.

We determined the pKa values of acidic residues in hen lysozyme by comparing the pH dependency of stability between wild type and mutant lysozymes in which a negative charge is eliminated. In the comparison of the stability between wild type and a mutant lysozyme, the difference in pH titration curve between them could be expressed as a two-state process involving protonation of a single acidic residue. The results strongly indicated that the Aune and Tanford theory of protein denaturation [Aune, K.C. and Tanford, C. (1969) Biochemistry 8, 4579-4585] is applicable to protein stability in solution. On the other hand, the pKa values of acidic residues in the presence of low (5 mM) or high (400 mM) salt concentration were determined by means of two-dimensional NMR. We found that the pKa values obtained from the pH dependency of stability were close to those from the NMR experiment under the high salt condition. Moreover, by comparing pKa values at high salt and low salt concentrations, we could evaluate the dependency of two electrostatic interactions (salt bridge and charge-helix dipole interaction) on salt concentration.

Amino Acids↗
PubMed1995

[Anesthetic management of a patient with cardiac sarcoidosis].

We report the anesthetic management of a patient with cardiac sarcoidosis. Cardiac sarcoidosis is characterized by a high incidence of complete atrioventricular block, right bundle branch block, and ventricular arrhythmias. Cases of sudden death during stable cardiac function have been reported. Therefore, careful anesthetic management is necessary. The patient was premedicated with scopolamine, intramuscularly. Before the induction, he received lidocaine, propranolol, and pentazocine, intravenously. Anesthesia was induced with midazolam and vecuronium, and the trachea was intubated. Anesthesia was maintained with nitrous oxide, sevoflurane in oxygen. Anesthetic method adapted to prevent severe complications including sudden death resulted in good condition of the patient during the perioperative period.

Adult↗
PubMed1994

Decreased cerebrospinal fluid levels of beta-endorphin in Japanese patients with Joseph disease.

We measured the cerebrospinal fluid (CSF) levels of beta-endorphin in 7 Japanese patients with Joseph disease and compared them with control values. The 7 patients included 4 with type I and 3 with type II disease; their mean age was 45.7 +/- 12.09 years. Diseased controls were matched in age to the patients studied. In these patients, CSF beta-endorphin level was significantly lower than in the controls (40% of normal values). An alteration in CSF beta-endorphin level may explain some of the neurological impairment found in Joseph disease.

Adult↗
PubMed1994

A family of McLeod syndrome, masquerading as chorea-acanthocytosis.

A man, aged 52, is reported to show (1) adult onset, (2) progressive orofacial dyskinesia and choreic movements of the extremities, (3) tongue biting, (4) denervation of the peripheral nerves, (5) acanthocytosis, and (6) increased serum creatine kinase, which are characteristic of chorea-acanthocytosis. The Kell blood group examination on erythrocytes disclosed that the propositus had McLeod phenotype, and his mother and one of his sisters were carriers of the McLeod phenotype. Thus, he was diagnosed as having McLeod syndrome. A criterion of exclusion of McLeod phenotype on erythrocytes should be added to the diagnostic criteria of chorea-acanthocytosis. Moreover, chronic neurogenic changes instead of myogenic changes were electromyographically and histopathologically verified in the muscle.

Acanthocytes↗