Biomedical subjects

C Mukai

Publications and source records attributed to C Mukai.

At least 55 records · Page 3Linked to original sources

PubMed1996

Microgravity induces prostaglandin E2 and interleukin-6 production in normal rat osteoblasts: role in bone demineralization.

It has been suggested that microgravity alters bone metabolism. Evidence for this phenomenon includes the negative calcium balance and decreased bone density in astronauts, as well as, inhibition of bone formation in rats flown for 2 to 3 weeks. However, the specific mechanisms that modulate these changes in microgravity are unknown. The purpose of this study was to clarify the mechanism of microgravity-induced bone demineralization using normal rat osteoblasts obtained from femur marrow cultures. The osteoblasts were cultured for 5 days during a Shuttle-Spacelab flight (STS-65). After collection of the culture medium, the cellular DNA and RNA were fixed on board. Enzyme-immunoassay of the culture medium for prostaglandin E2 (PGE2) indicated that microgravity induced a 4.5- to 136-fold increase in flight samples as compared to the ground control cultures. This increase of PGE2 production was consistent with a 3.3- to 9.5-fold elevation of inducible prostaglandin G/H synthase-2 (PGHS-2) mRNA, quantitated by reverse transcription-polymerase chain reaction (RT-PCR). The mRNA induction for the constitutive isozyme PGHS-1 was less than that for PGHS-2. The interleukin-6 (IL-6) mRNA was also increased (6.4- to 9.3-fold) in microgravity as compared to the ground controls. Since PGE2 and IL-6 are both known to play a role in osteoclast formation and bone resorption, these data provide molecular mechanisms that contribute to our understanding of microgravity-induced alterations in the bone resorption process.

Animals↗

PubMed1996

[Measurement of the common carotid arterial flow during parabolic flight in the anesthetized rat].

To measure the blood flow of a common carotid artery (CCA) during parabolic flight in the rat, we developed an animal double hold box (ADHB) made of styrene expanded form for the anesthetized rat to keep the animal at a proper posture in an aircaft. Twelve anesthetized rats weighing 291-342 g were surgically operated to mount a ultrasound flowmeter probe (1 mm size,1RS:Transonic Systems Inc.) around the right CCA and to insert a catheter into the right axillar artery for blood pressure measurement. These animals were held comfortably in ADHBs which were placed on the rack installed in the aircraft (MU-300). A total of 27 parabolic flights was performed and the blood flow was measured accurately in 9 rats. This special animal holding facility is useful for various types of animal experiments in an aircraft.

Animals↗

PubMed1996

Sympathetic outflow response to muscle during vestibular stimulation in humans.

To observe the effects of caloric vestibular stimulation on muscle sympathetic nerve activity (MSNA) in humans, 14 healthy volunteers were monitored in a supine position by electrocardiogram (ECG), blood pressure (BP), electro-oculogram (EOG). MSNA was monitored by a double recording technique of microneurography from the bilateral tibial nerves. Caloric vestibular stimulation was loaded by injecting 50 ml 44 degrees C warm water and 50 ml 10 degrees C cold water alternately into the external meatus for 1 min. Nystagmus was evoked in all cases by cold stimulation and in some cases by hot stimulation. The nystagmus evoked by cold stimulation was more intense than that by hot stimulation. MSNA was enhanced by either cold or hot stimulation; however, the enhancement mode differed between cold and hot stimulation. Cold stimulation evoked two peaks of MSNA while hot stimulation elicited only one peak. The first peak (404.5 +/- 115.4% with control value set at 100%, mean +/- SE) was estimated to be caused by cold stimulation on the skin of the external meatus while the second peak (379.2 +/- 65.3%) seemed to be the result of vestibular stimulation. With hot stimulation, the response peak of MSNA was 243.3 +/- 28.1%. In general, MSNA was enhanced after vestibular stimulation with MSNA increases was proportional to the stimulated level of the vestibular system.

Adult↗

PubMed1994

[Development of highly stereoselective reactions based on tricarbonyl(eta 6-o-trimethylsilylbenzaldehyde)-chromium(o) complex].

Treatment of the tricarbonyl(eta 6-o-trimethylsilylbenzaldehyde)chromium (O) complex with cyclic silyl enol ether species under the Mukaiyama condition resulted in highly stereoselective formation of syn-aldol products, whereas the aldol reaction with O-silyl ketene O,S-acetals afforded the corresponding anti-products in a highly stereoselective manner. The tricarbonyl(eta 6-o-trimethylsilyl-benzaldehyde)chromium(O) complex has also emerged as an excellent substrate for highly regio- and stereoselective construction of cis-3,5-isoxazolidine derivatives in the 1,3-dipolar cycloaddition reaction. By taking advantage of our newly developed aldol reaction, we have succeeded in highly stereocontroled syntheses of some biologically active compounds such as C-13 side chains of taxol and taxotère, the N-terminal amino acid of nikkomycin B and Bx, and antitumor styryllactones: goniofufurone, goniotriol, and goniothalenol.

Molecular Conformation↗

PubMed1993

Echocardiograms during six hours of bedrest at head-down and head-up tilt and during space flight.

Left ventricular end-diastolic volume increased after 4 1/2 to 6 hours of space flight, but was significantly decreased after 5 to 6 days of space flight. To determine the role of acute gravitational effects in this phenomenon, responses to a 6-hour bedrest model of 0 gravity (G; 5 degrees head-down tilt) were compared with those of fractional gravity loads of 1/6 G, 1/3 G, and 2/3 G by using head-up tilts of 10 degrees, 20 degrees, and 42 degrees, respectively. On 4 different days, six healthy male subjects were tilted at one of the four angles for 6 hours. Cardiac dimensions and volumes were determined from two-dimensional and M-mode echocardiograms in the left lateral decubitus position at control (0), 2, 4, and 6 hours. Stroke volume decreased with time (P < .05) for all tilt angles when compared with control. Ejection fraction (EF) at -5 degrees was greater than at +20 degrees and +42 degrees (not significant); EF at +10 degrees was greater than at +42 degrees (not significant). For the tilt angles of -5 degrees, +10 degrees, and +20 degrees, mean heart rate decreased during the first 2 hours, and returned to control or was slightly elevated above control (+20 degrees) by 6 hours (not significant). At the +42 degrees angle of tilt, heart rate was increased above control at hours 2, 4, and 6. There were no significant differences in cardiac output at any time point for any tilt angle.(ABSTRACT TRUNCATED AT 250 WORDS)

Bed Rest↗

PubMed1993

Congenital ankyloglossia with deviation of the epiglottis and larynx: symptoms and respiratory function in adults.

We operated on 38 adult patients with congenital ankyloglossia with deviation of the epiglottis and larynx. The results were as follows. 1) Most patients had Angle's class III malocclusion, irregular alignment of the upper teeth, and high hard palate. 2) Fifty percent of the patients in our study population had obstructive respiratory failure. Their vital capacity increased significantly after the operation, but changes of forced expiratory volume in 1 second were not prominent. 3) Subjective symptoms of this disease were stiffness of the shoulders, a cold feeling in the extremities, an obstructed feeling in the throat, insomnia, fatigue, dry skin, irritability and/or anxiety, and nervousness. These improved postoperatively. 4) Objective symptoms included snoring, muscle cramps, difficulty in playing wind instruments, hoarseness, and incorrect articulation. The objective symptoms, except for incorrect articulation, improved postoperatively.

Adult↗

PubMed1992

Digit sucking.

Explore the source record for details and available documents.

Female↗

PubMed1991

Orthostatic function during a stand test before and after head-up or head-down bedrest.

Astronauts may exhibit orthostatic dysfunction upon returning to 1 g after space flight. Understanding cardiovascular changes at 0 G will provide insights into the mechanisms of the loss of orthostatic tolerance, whether due to space flight or bedrest. Bedrest is one model used to produce cardiovascular changes that are associated with space flight. In the current study, young male adults were placed at -5 degrees, +10, +20, or +42 degrees bedrest (0, 1/6, 1/3, and 2/3g, respectively) for 6 hours on 4 different days. This was preceded and followed by a stand test: 5 minutes in the supine position, and then 5 minutes in the standing position, with the feet 9 inches apart and 6 inches from the wall. Cardiovascular values were measured at 1-minute intervals. Systolic and diastolic pressures were measured using an automated blood pressure device; mean arterial pressure (MAP; mm Hg) was calculated. Heart rate (bpm) and cardiac parameters were measured with a thoracic impedance device. Minute 3, 4, and 5 values were used to determine whether there were time or angle effects. Of six subjects, one reported nausea upon 3 minutes of standing after 6 hours of bedrest at -5 degrees. The same subject was lightheaded in the first minute of standing after 6 hours of bedrest at +10 degrees. Mean heart rate pre-bedrest in the supine position was 63 and increased by 24 bpm on standing. Heart rate post-bedrest in the supine position was 65 and increased by 35 bpm on standing; standing heart rate increased 11 bpm after -5 degrees bedrest. The increases after +10 degrees, +20 degrees, and +42 degrees tilts were 4, 3, and 4 bpm, respectively. Changes in the mean arterial blood pressure were minimal. Results from the stand test pre- and post- 6 hours of bedrest at -5 degrees but not at +10 degrees, +20 degrees, or +42 degrees are similar to those after space flight.

Adult↗

PubMed1991

Ankyloglossia with deviation of the epiglottis and larynx.

We observed ankyloglossia to be usually accompanied by displacement of the epiglottis and larynx. Infants with this disease developed dyspnea and skin and hair abnormalities. In addition, they had other symptoms, such as a dark forehead, a frowning expression, a dark color around the lips, scanty eyebrows, swelling around the palpebrae, harsh respiratory sounds, hard crying, snoring, and frequent yawning. In spite of these abnormalities, they had been considered to be healthy by their pediatricians. Arterial oxygen percent saturation (SaO2) was measured while the infants were asleep, suckling, and awake. The results revealed that their SaO2 was unstable and slightly low. The symptoms and signs of this disease were very similar to those observed in victims of sudden infant death syndrome before their death. Correction of the ankyloglossia and deviation of the epiglottis and larynx resulted in great improvement of these signs as well as a stabilization and increase of SaO2.

Cyanosis↗

PubMed1990

Acute and intermediate cardiovascular responses to zero gravity and to fractional gravity levels induced by head-down or head-up tilt.

Determination of early cardiovascular responses to simulated gravity levels between 0 and 1 G will add knowledge of cardiovascular responses to space flight. Cardiovascular responses to 6 hours in a -5 degrees head-down bedrest model of weightlessness (0 G) were compared to those in head-up tilts of +10 degrees, +20 degrees, and +42 degrees (1/6, 1/3, and 2/3 G, respectively). Six healthy young adult males experienced the four angles on separate days. Impedance cardiography was used to measure thoracic fluid index, cardiac output, stroke volume, and peak flow. Although much intersubject variation occurred, the mean thoracic fluid content at -5 degrees decreased during the first hour and remained decreased; 6-hour values were similar to +10 degrees and +20 degrees. Heart rate decreased the first 2 hours for all angles, then increased, converging at 3-4 hours, and reached control by hour 6. Stroke volume decreased for the first 3 hours at -5 degrees, +10 degrees, +20 degrees; values at all four angles converged at hour 3 and increased in unison thereafter. Cardiac output and peak aortic flow reflected the angle at start of tilt; values at all angles converged by the second hour, decreased through the third hour, and increased thereafter. Pulse pressure decreased for the first 3 hours for angles -5 degrees, +10 degrees, and +20 degrees, converged at the fourth hour, and returned to control. Peak flow at +42 degrees was constant for the first 3 hours and increased thereafter. Blood pressure decreased for the first 2 hours, although the greatest decrease occurred at -5 degrees and +42 degrees; thereafter, values at all angles increased in unison and converged at the fourth hour. Total peripheral resistance increased during the first hour at -5 degrees and +20 degrees and decreased from hour 3 to hours 5-6 at the +42 degrees angle. Cardiovascular values were related to tilt angle for the first 2 hours of tilt, but after hour 3 values at all four angles began to converge, suggesting that cardiovascular homeostatic mechanisms seek a common adapted state regardless of effective gravity level (tilt angle) up to 2/3 G.

Bed Rest↗

PubMed1990

[Experiments of contamination with bacteria while transfusion between the newly developed porous polymer plug and by air needle plug].

We newly developed a transfusion plug that has an air passage of polymer porous material (I Cap). This porous polymer material theoretical does not pass the infectious microorganisms. We experimented contaminations during the transfusions by I Cap and that using air needles. Trypticated soy broth was used for the experiments. Experiments of transfusion in a dusty environment revealed that the transfusions by air needles got 100% contamination and that by I Cap was 0%. The experiments in a clinic room transfusions also revealed that air needle resulted in 30.3% contamination but on the contrary 0% with the I Cap. Dusty air was flown under high pressure (1.5 atmospheric pressure) through the same filter of I Cap for 30 minutes into the trypticated soy broth. These experiments revealed that the filter did not permeate bacteria and that transfusions with air needle was contaminated with dust.

Air↗

PubMed1989

Acute hemodynamic responses to weightlessness in humans.

As NASA designs space flights requiring prolonged periods of weightlessness for a broader segment of the population, it will be important to know the acute and sustained effects of weightlessness on the cardiovascular system since this information will contribute to understanding of the clinical pharmacology of drugs administered in space. Due to operational constraints on space flights, earliest effects of weightlessness have not been documented. We examined hemodynamic responses of humans to transitions from acceleration to weightlessness during parabolic flight on NASA's KC-135 aircraft. Impedance cardiography data were collected over four sets of 8-10 parabolas, with a brief rest period between sets. Each parabola included a period of 1.8 Gz, then approximately 20 seconds of weightlessness, and finally a period of 1.6 Gz; the cycle repeated almost immediately for the remainder of the set. Subjects were semi-supine (Shuttle launch posture) for the first set, then randomly supine, sitting and standing for each subsequent set. Transition to weightlessness while standing produced decreased heart rate, increased thoracic fluid content, and increased stroke index. Surprisingly, the onset of weightlessness in the semi-supine posture produced little evidence of a headward fluid shift. Heart rate, stroke index, and cardiac index are virtually unchanged after 20 seconds of weightlessness, and thoracic fluid content is slightly decreased. Semi-supine responses run counter to Shuttle crewmember reports of noticeable fluid shift after minutes to hours in orbit. Apparently, the headward fluid shift commences in the semi-supine posture before launch. is augmented by launch acceleration, but briefly interrupted immediately in orbit, then resumes and is completed over the next hours.

Adult↗

PubMed1989

[Use of Rokitamycin dry syrup in cases of upper deep cervical lymphadenitis and otitis media with exudatives].

Dry syrup of Rokitamycin (RKM.DS), a new macrolide antibiotic with 16-membered ring developed by Toyo Jozo Co., Ltd., was used on cases of upper deep cervical lymphadenitis (UDCL) and of otitis media with exudatives (OME) likely caused by chlamydia infections, and its clinical effects were investigated. 1) In four cases of UDCL (C. psittaci infections), daily doses of 20.0-28.6 mg/kg were administered for 10-42 consecutive days and good efficacies were observed with two cases of excellent results and two cases of good results. 2) In one case of OME (C. trachomatis infection) a daily dose of 30.0 mg/kg was administered for 15 consecutive days and good effectiveness was observed. 3) No side effect was observed in any of the cases. From the above results, it became clear that RKM.DS could effectively used as a therapeutic agent for UDCL and OME in children.

Child↗

PubMed1987

GTP-binding proteins in etiolated epicotyls of Pisum sativum (Alaska) seedlings.

Seven fractions of GTP-binding proteins separated by gel filtration of an extract of epicotyls of Pisum sativum seedlings were partially characterized. Seven fractions of GTP-binding proteins tentatively designated GP1 to GP7 had the capacity to be ADP-ribosylated by pertussis toxin. Pooled fractions of GP2 to GP7 showed Km values 2, 20, 50, 10, 3 and 1 nM, respectively. The binding of [35S]GTP gamma S to GTP-binding proteins was prevented competitively in the presence of 0.1 mM GTP and also prevented in the presence of 0.1 mM ATP. Binding of [35S]GTP gamma S to the proteins produced a decrease in their molecular weights.

Adenosine Diphosphate Ribose↗

PubMed1987