PubMed Health⌕ Search

Biomedical subjects

N Takaoka

Publications and source records attributed to N Takaoka.

15 recordsLinked to original sources
PubMed2001

Noble-gas-rich chondrules in an enstatite meteorite.

Chondrules are silicate spherules that are found in abundance in the most primitive class of meteorites, the chondrites. Chondrules are believed to have formed by rapid cooling of silicate melt early in the history of the Solar System, and their properties should reflect the composition of (and physical conditions in) the solar nebula at the time when the Sun and planets were forming. It is usually believed that chondrules lost all their noble gases at the time of melting. Here we report the discovery of significant amounts of trapped noble gases in chondrules in the enstatite chondrite Yamato-791790, which consists of highly reduced minerals. The elemental ratios 36Ar/132Xe and 84Kr/132Xe are similar to those of 'subsolar' gas, which has the highest 36Ar/132Xe ratio after that of solar-type noble gases. The most plausible explanation for the high noble-gas concentration and the characteristic elemental ratios is that solar gases were implanted into the chondrule precursor material, followed by incomplete loss of the implanted gases through diffusion over time.

Journal Article↗
PubMed2001

A novel missense mutation in human lactate dehydrogenase B-subunit gene.

Reduced activity of serum lactate dehydrogenase (LDH; EC 1.1.1.27) was found in a male medical student during practical examinations of his own blood. Serum LDH isoenzyme pattern showed reductions in activities of the isoenzymes with lower subunit A/B ratios such as LDH1 and LDH2. These findings were indicative of a partial LDH-B subunit deficiency, which was confirmed in erythrocyte hemolysates by Western blotting. Polymerase chain reaction (PCR)-based DNA sequence analysis of the LDH-B subunit gene revealed a heterozygous nucleotide change: a guanine to adenine substitution in codon 69 (GGG --> GAG) at the third exon of the LDH-B subunit gene that resulted in a glycine to glutamic acid substitution (G69E). The mutation was confirmed by PCR-restriction fragment length polymorphism (RFLP) analysis using a mismatched primer to introduce a new NcoI restriction site. The same heterozygous mutation was found in his mother but not in other family members. This mutation involves a residue belonging to alphaC helix in LDH-B subunit protein molecule that functions as an interface for other subunits.

Adult↗
PubMed1999

Promoter analysis of the membrane protein gp64 gene of the cellular slime mold Polysphondylium pallidum.

We cloned a genomic fragment of the membrane protein gp64 gene of the cellular slime mold Polysphondylium pallidum by inverse PCR. Primer extension analysis identified a major transcription start site 65 bp upstream of the translation start codon. The promoter region of the gp64 gene contains sequences homologous to a TATA box at position -47 to -37 and to an initiator (Inr, PyPyCAPyPyPyPy) at position -3 to +5 from the transcription start site. Successively truncated segments of the promoter were tested for their ability to drive expression of the beta-galactosidase reporter gene in transformed cells; also the difference in activity between growth conditions was compared. The results indicated that there are two positive vegetative regulatory elements extending between -187 and -62 bp from the transcription start site of the gp64 promoter; also their activity was two to three times higher in the cells grown with bacteria in shaken suspension than in the cells grown in an axenic medium.

Animals↗
PubMed1997

[A case of Wilson-Mikity syndrome with marked and monoclonal elevation of IgM in blood].

Wilson-Mikity syndrome, a chronic respiratory insufficiency occurring in premature newborn infants, is known to show an elevation of serum IgM, but its etiology is obscure. We studied the immunological properties of IgM in a female infant of this syndrome, whose IgM in cord blood was very high level at 639.1 mg/dl with monoclonal elevation. The IgM bound to protein(s) in human umbilical venous endothelial cells and in human lung tissue. However, IgMs from this patient after recovery, from patient's mother and from another normal newborn did not bind to the proteins. Tissue-binding activity of the patient's IgM may be associated with tissue damages in this syndrome.

Female↗
PubMed1997

[Clinical significance of valvular regurgitation during long-term antihypertensive therapy in patients with mild to moderate essential hypertension].

Changes in valvular function and blood pressure level during long-term pharmacological anti-hypertensive therapy were investigated in patients with mild to moderate essential hypertension. Sixty-seven patients with hypertension (mean [+/-SD] 60 +/- 10 years) were followed up for 5.4 +/- 1.6 years with antihypertensive medication. During the follow-up period, valvular dysfunction was assessed by color Doppler echocardiography. Increased mitral valve regurgitation > or = grade II and/or aortic valve regurgitation > or = grade II were aggravated in 17 patients, whereas the other 50 patients did not reveal any significant changes in valvular functions. Systolic blood pressure and end-systolic wall stress at the end of the follow-up period were higher in the aggravated group (156 +/- 30 mmHg and 79 +/- 23 dyne/cm2) than in the unchanged group (143 +/- 17 mmHg and 63 +/- 18 dyne/cm2). Dimensions of the left atrium and left ventricle at both systole and diastole were enlarged in the aggravated group (37 +/- 4 to 40 +/- 4, 31 +/- 4 to 33 +/- 4 and 48 +/- 3 to 51 +/- 3 mm, respectively), but not in the unchanged group. Nine patients in the aggravated group received additional treatment with imidapril hydrochloride over 6 months in an attempt to further reduce blood pressure levels, resulting in significant improvements in systolic blood pressure (151 +/- 12 to 129 +/- 7 mmHg), diastolic blood pressure (91 +/- 4 to 79 +/- 8 mmHg), left atrial dimension (41 +/- 3 to 39 +/- 3 mm) and left ventricular end-diastolic dimension (49 +/- 4 to 48 +/- 3 mm). Adequate pharmacological intervention can ameliorate valvular dysfunction, left ventricular enlargement and increased ventricular wall stress.

Adult↗
PubMed1995

Relations among heart rate, immediate memory, and time estimation under two different instructions.

The present study was done to elucidate the relations among heart rate, digit memory, and time estimation under two different instructions, standard and evaluative. 60 women heard and recalled 8 digits. Subjects reproduced 4-, 8-, and 16-sec. durations of a buzzer and also estimated the durations. Data were discussed in terms of the hypothesis of an inverted U-shaped relationship between arousal and performance. These data suggest relations among the three variables which were influenced by two different instructions.

Adolescent↗
PubMed1994

Pyruvic acid production by an F1-ATPase-defective mutant of Escherichia coli W1485lip2.

An F1-ATPase-defective mutant, TBLA-1, was constructed by the transduction of a defective gene for the alpha subunit of F1-ATPase, atpA401, into Escherichia coli W1485lip2, a lipoic acid-requiring pyruvic acid producer. The pyruvic acid production of the strain TBLA-1 was found to be improved markedly compared with that of strain W1485lip2. In cultures using a jar fermentor, the strain W1485lip2 consumed 50 g/liter of glucose and produced 25 g/liter of pyruvic acid after culture for 32h, while strain TBLA-1 consumed the same amount of glucose, and produced more than 30 g/liter of pyruvic acid in a 24-h culture. A revertant, No. 63-1, derived from the strain TBLA-1, had a normal level of F1-ATPase activity, and showed a similar pattern of pyruvic acid production to that of strain W1485lip2.

Escherichia coli↗
PubMed1993

[Respiratory changes in the blood flow pattern of the superior vena cava in patients with chronic obstructive pulmonary diseases].

Blood flow patterns in the superior vena cava (SVC) obtained from 20 elderly cases of COPD (aged 60-81) were compared with those from 24 elderly normal subjects (aged 61-80). The peak flow velocity and duration of two major antegrade flows during systole and diastole (S & D wave) were both qualitatively and quantitatively assessed with pulsed Doppler echocardiography. While peak flow velocity and duration of the S and D waves increased during inspiration and decreased during expiration in normal subjects, respiratory variations of these antegrade waves were extremely greater in patients with COPD with augmented and/or fused antegrade waves during inspiration, and there decrease was associated with an upward shift above the zero level during expiration. The duration of the D wave was significantly longer in COPD patients than in normal subjects and also revealed a significantly positive correlation with FEV1.0%. These findings suggest that SVC flow pattern is useful for the assessment of early right ventricular dysfunction in patients with COPD, but further clinical studies are required to confirm this thesis.

Aged↗
PubMed1991

[Hypertrophic cardiomyopathy associated with anomalous origin of the left coronary artery from the right sinus of valsalva].

A 47 year old Japanese male with exertional shortness of breath, cardiac murmur and ECG abnormalities was examined with invasive and non-invasive cardiology techniques that disclosed hypertrophic cardiomyopathy, and the anomalous origin of the left coronary artery from the right sinus of Valsalva. Although both situations have been known to cause sudden death especially under a state of strenuous physical stress, his exercise thallium scintigraphy performed with the symptom limited maximal test did not uncover any significant myocardial ischemia or exercise induced malignant arrhythmias. This is a very rare association of two distinctly identified clinical situations highly indicative of a likelihood of sudden cardiac death. Therefore, careful observation is needed.

Cardiac Catheterization↗
PubMed1988

Comparison of the effects of benzodiazepine and nonbenzodiazepine anxiolytics on mouse-killing behavior in rats.

The present study investigated the effects of nonbenzodiazepine anxiolytics on mouse-killing behavior in rats, compared with the effects of benzodiazepine anxiolytics. Mouse-killing behavior was induced by bilateral olfactory bulbectomy. The following drugs were administered intraperitoneally: chlordiazepoxide, diazepam, ethyl loflazepate, fludiazepam, zopiclone, suriclone, and CL 218,872. Among these drugs, suriclone (ED50 = 1.3 mg/kg) and fludiazepam (ED50 = 5.9 mg/kg) showed potent suppressive effects. Diazepam, ethyl loflazepate, and CL 218,872 showed only weak actions on mouse-killing behavior.

Aggression↗
PubMed1988

Characteristics of coping behavior of rats exposed to a long-term hardly escapable aversive stimulus: a possible depression model.

The purpose of the present study was to induce a state of depression including both the elements of behavioral despair and chronic stress. Therefore, this study was performed under the hypothesis that a long-term exposure of rats to the experimental situation of difficult to escape from foot-shock in a Skinner box might produce animals with a state of depression containing both the elements. Male Wistar strain rats were trained to press a lever to escape from foot-shock under a fixed ratio (FR) schedule. After the training, rats were exposed daily to a schedule consisting of 20 trials (the early 10 trials, FR 5; the later 10 trials, FR 20) once a day. The exposure resulted in reduction of the number of lever presses and successful escape in FR 20. Only the animals whose number of escapes, reduced to under 20% in FR 20 were treated with psychotropic drugs once a day for 4 days. The results showed that the reduced number of escapes was most improved by antidepressants (imipramine or mianserin), but not by haloperidol and methamphetamine. Although subchronic treatment with chlordiazepoxide partially recovered the reduced escape, the efficiency of lever pressing to escape from foot-shock was lower than that with the antidepressants. The results of the present study suggest that the behavioral suppression observed in this study might include characteristics similar to a state of depression.

Adaptation, Psychological↗