Biomedical subjects

K Nonaka

Publications and source records attributed to K Nonaka.

317 records · Page 18Linked to original sources

PubMedDate not supplied

Genetic study of the craniofacial growth in male rats by factor scores.

The craniofacial growth of F1 male offspring produced by a complete diallel cross of five strains of rats was observed with the use of cephalometry. Factor analysis was applied to several dimensions of dorsoventral and lateral cephalograms to assess the integration of the craniofacial complex with growth. The first three factors were chosen in each cephalogram, resulting in an explanation of 50.7% and 59.3% of the variation in the dorsoventral and lateral cephalograms, respectively, on an average throughout the period of the experiment, and disclosing that Factor I was associated most closely with the change in the craniofacial growth of rats. A further genetic analysis of the factor scores of each offspring lead to the conclusion that the growth changes of craniofacial width and length were more strongly influenced by the genetic effects; while those of upper jaw, nasal cavity, and pharyngeal part were more strongly influenced by the environmental effects.

Animals↗

PubMedDate not supplied

Systemic study of the hemodynamic effects of sublingual nitroglycerin in unanesthetized dogs.

The cardiovascular effects of nitroglycerin, given sublingually and intravenously in a clinical dose range, were studied in unanesthetized and unrestrained normal dogs. The parameters examined included coronary blood flow, coronary conductance arterial diameter, internal diameter of the left ventricle, blood flow in the aorta and vena cava, diameters of the aorta, carotid, mesenteric, iliac, internal thoracic and pulmonary arteries and vena cava, pressures in the left ventricle, abdominal aorta and pulmonary arteries, organ thickness of the spleen, liver and sartorius muscle, and rate of rise in arterial pressure pulses. It was suggested that nitroglycerin does not dilate the veins in the splanchnic area and hind limb, but efficiently dilates conductance arteries. It was concluded that the therapeutically important effects of nitroglycerin involve the dilatation of conductance arteries, including both coronary and general systemic arteries. The effect of the former would be directly on stenotic lesions in the epicardial large coronary artery, improving blood flow to the ischemic part of the myocardium, whereas the latter might be beneficial for reducing cardiac work and lowering systolic pressure by increasing the Windkessel volume. Therefore, the heart regains its ventricular function and pumps stagnant blood from heart, lungs and veins to the arterial side, resulting in a reduction of the elevated preload to normal levels in anginal patients.

Administration, Sublingual↗

PubMedDate not supplied

The effect of embryo transfer on the intrauterine growth of the mandible in mouse fetuses.

A DDD/Qdj strain of embryos was transferred to the same strain of recipient females to examine the effect of the embryo transfer procedure on the intrauterine growth of the mandible in mouse fetuses. Just after parturition, the litter size and the gestation period were recorded and the mandibular size of the newborn offspring was measured by use of an image analyzing system. The mandibular size of the newborn offspring developed from the transferred embryos was compared with that of the newborn offspring developed from the nontransferred embryos. The following results were obtained: 1) There was no gender difference in the mandibular size of the newborn offspring from either the transferred or nontransferred embryos. 2) An inverse relation between the litter size and the mandibular size of the newborn offspring was observed, while a direct relation between the gestation period and the mandibular size of the newborn offspring was observed. 3) The litter size in the transferred group was smaller than that of the nontransferred group, while the gestation period in the transferred group was longer than that of the non-transferred group. After adjusting for the effects of the litter size and the gestation period on the mandibular size for both groups, the adjusted mandibular size of the newborn offspring in the transferred group was significantly smaller than that of the nontransferred group. Thus, it is concluded that the embryo transfer procedure retards the intrauterine growth of the mandible in mouse fetuses developed from transferred embryos.

Animals↗

PubMedDate not supplied

The effect of four strains of recipients on the intrauterine growth of the mandible in mouse fetuses.

The embryo transfer technique is a very useful tool for determining the intrauterine effect of the dam on the prenatal growth of the embryo. In the present study, a DDD/Qdj strain of embryos was transferred to four strains of recipients (DDD/Qdj, C3H/Qdj, C57BL/Qdj, and DBA/1J Sea). The litter size and the gestation period were recorded and the mandibular size of the newborn offspring was measured by an image analyzing system. A comparison among the four strains of recipients was performed to examine the effect of the strain of the recipient on the intrauterine growth of the mandible in mouse fetuses. The following results were obtained. 1) There were no interstrain differences in the litter size and the gestation period among the four strains of recipients. 2) There was an inverse relation between the litter size and the mandibular size, while there was a direct relation between the gestation period and the mandibular size. 3) There was a strong effect of the strain of the recipient on the mandibular size of the newborn offspring. 4) After eliminating these effects of the litter size and the gestation period on the mandibular size, a significant interstrain difference in the adjusted mandibular size of the newborn offspring developed from the DDD/Qdj strain of embryos transferred to the four strains of recipients was found. It is suggested that the four strains of recipients might unequally affect the intrauterine growth of the mandible in the mouse fetuses, which were derived from the same DDD/Qdj strain of transferred embryos.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Genetic and environmental effects on preimplantation development of mouse embryo in vitro.

To examine the degree of the relative contribution of genetic and environmental effects to preimplantation development of mouse embryo in vitro, two-cell stage embryos collected from oviducts of five strains of inbred mice (DDD/Qdj, C3H/Qdj, C57BL/6J Sea, DBA/1J Sea, and BALB/C Sea) were cultivated up to the stage of expanded blastocyst for 72 hr. Both fertility and survival rates were calculated in each recipient and also in each strain. A Student-Newman-Keuls test for both rates showed a significant inter-strain difference and an analysis of variance done to estimate the relative importance of genetic and environmental effects on the preimplantation development of embryo showed a low degree of genetic determination for both rates. It was thus possible to conclude that the environmental effect played a more important role on preimplantation development of mouse embryo in vitro.

Animals↗

PubMedDate not supplied

Intrauterine effect of dam on prenatal development of craniofacial complex of mouse embryo.

Embryo transfer effect and intrauterine effect of the dam on prenatal development of the craniofacial complex of mice embryos were investigated with the use of embryo transfer and cephalostat. DDD strain embryos were transferred to the three strains of recipients (DDD, C57BL, and DBA). The cephalometric observation of newborn offspring developed from transferred embryos was performed just after parturition. Dorso-ventral craniofacial size of newborn offspring was calculated using values of X- and Y-coordinates on a dorsoventral cephalogram. Statistical analysis showed that a significant intergroup difference in craniofacial size between transferred and nontransferred groups as well as a significant inter-strain difference among those of the three strains of recipients were observed. Thus, it was disclosed that embryo transfer technique might retard the prenatal development of craniofacial complex of transferred embryo and that the three strains of recipients contributed unequally to the prenatal development of craniofacial complex of transferred embryo through each of their intrauterine environments as a prenatal maternal effect. These results indicated that the intrauterine environment of the recipient played an important role in the prenatal development of the craniofacial complex of the mice embryo.

Animals↗

PubMedDate not supplied

The effect of dam strain on the craniofacial morphogenesis of CL/Fr mouse fetuses.

The embryo transfer technique and cephalometry were used to investigate the effect of dam strain in intrauterine craniofacial growth and the severity of cleft lip and palate (CLP) in a CLP-susceptible CL/Fr strain of embryos. The CL/Fr strain of embryos at early blastocyst stage was transferred to the same dam strain and to the CLP-resistant C57BL dam strain. On the 18th gestational day, each dam was laparotomized to take out the fetuses. The spontaneous incidence of CLP in the fetuses was checked and a cephalometric observation of the craniofacial complex of each fetus was done just after laparotomy. The dorsoventral craniofacial size of the unaffected fetuses and the severity of CLP i the affected ones were compared between both dam strains. The following results were obtained: 1) The overall craniofacial sizes of the unaffected fetuses observed in the CL/Fr dam strain were significantly smaller than those seen in the C57/BL dam strain. Those of the affected fetuses observed in the CL/Fr dam strain were smaller than those seen in the C57BL dam strain although the interstrain difference was not significant. 20 The dam strain had a highly significant effect on the craniofacial size of the unaffected fetuses. 3) The CLP frequency in the CL/Fr dam strain was significantly higher than that in the C57BL dam strain. 4) The severity of CLP in the affected fetuses observed in the CL/Fr dam strain was significantly more serious than that seen in the C57BL dam strain. These results indicated that the CLP-susceptible CL/Fr dam strain retarded the intrauterine craniofacial growth of the fetuses and that the cleft condition in the affected fetuses observed in the CL/Fr dam strain was more seriously affected than that seen in the CLP-resistant C57BL dam strain. Thus, it can be concluded that the effect of the dam strain played an important role in the craniofacial morphogenesis of the CL/Fr strain of mouse fetuses that developed from the embryo transferred to the CL/Fr and C57BL dam strains along with the genotype of embryos.

Animals↗

PubMedDate not supplied

The strain effect of dam on intrauterine incisal growth in mouse fetuses.

The embryo transfer technique was carried out to examine the strain effect of dams on the intrauterine incisal growth of mouse fetuses. A mean of nine DDD/Qdj embryos was transferred to each female recipient of the four strains (DDD/Qdj, C3H/Qdjl C57BL/Qdj, and DBA/IJ Sea). The dam's weight, the litter size, the gestation period and the newborn offspring weight were recorded. The mandibular incisal size of the newborn offspring was measured two-dimensionally by means of an image analyzing system. Statistical analyses of the incisal size of the DDD/Qdj newborn offspring delivered from the four strains of recipients showed the following results: 1) There were significant interstrain differences in the dam's weight and the newborn offspring weight, but not in the litter size and the gestation period among the four strains of recipients. 2) There was an inverse relation between the litter size and the mandibular incisal size while there were direct relations between the dam's weight and the mandibular incisal size, and between the newborn offspring weight and the mandibular incisal size. 3) There was a significant strain effect of the dam on the mandibular incisal size of the newborn offspring. 4) After eliminating the effects of the litter size, the gestation period, and the newborn offspring weight on the mandibular incisal size of the DDD/Qdj newborn offspring developed in the four strains of dams, a significant interstrain difference in the adjusted mandibular incisal size was found (C3H/Qdj > DBA/IJ Sea > C57BL/Qdj > DDD/Qdj), suggesting that the uteri of the C3H/Qdj strain of dams provided a more suitable environment for the intrauterine incisal growth than those of the other three strains of dams. Thus, it is concluded that the strain effect of dam played an important role in the intrauterine incisal growth of mouse fetuses.

Animals↗

PubMedDate not supplied

A genetic study of dentin growth in the mandibular second and third molars of male mice.

Although the influence of genetic and environmental factors on the completed crown size of mandibular molars in mice is well known, such influence on the growth process of the mandibular second and third molars of mice has not yet been clarified. The purpose of the present study is to examine the growth pattern of the dentinal formation and evaluate the relative contributions of both genetic and environmental factors to longitudinal dentin formation by the use of the partial diallel cross-genetic approach, the time-marking method and a computerized image measurement system. The following results were obtained: 1) the onset of dentinal formation in the second molar was on the 6-9th day after birth, while that of the third molar was on the 9-12th day after birth; 2) the best fitted growth curve of the dentinal formation for the first molar was the fifth order polynomial equation, while for the second molar the fourth order polynomial equation was best, and for the third molar the third order polynomial equation was best; 3) maternal effect strongly influenced the second and the third molar dentin growth at an early stage of postnatal growth. Thus, it could be concluded that the dentinal formation growth pattern differed among the three kinds of mouse molars while maternal environmental factors, in addition to genetic factors, played an important role in the mouse second and third molar dentin growth during the early stage of postnatal growth.

Analysis of Variance↗

PubMedDate not supplied

A longitudinal study of the postnatal maternal effect on the craniofacial growth of mouse offspring by cross-nursing.

A cross-nursing experiment was conducted to examine the nursing dam strain effect on the postnatal growth of a newborn mouse offspring by simultaneously using larger DDD strain mice and smaller C57BL strain ones. A periodical cephalometric observation of the postnatal craniofacial growth of the offspring was longitudinally made from birth up to the 100th day of life in addition to measuring the offspring weight. According to multivariate statistical analyses, the following results were obtained: 1) The mean body weight of the DDD offspring cross-nursed by the C57BL dam was significantly lighter than that of the DDD offspring self-nursed by the DDD dam throughout the whole experimental period except at birth and on the 100th day. 2) The mean body weight of the C57BL offspring cross-nursed by the DDD dam was significantly heavier than that of the C57BL offspring self-nursed by the C57BL dam from the 10th day up to the 30th day. 3) There was a significant positive relationship between the offspring weight and the offspring craniofacial size throughout the entire experimental period in the C57BL offspring and from the 10th day up to the 40th day in the DDD offspring. 4) The nursing dam strain effect on the craniofacial size of the DDD offspring was also significant on the 30th, 60th, 80th, and 100th days. The adjusted craniofacial size of the DDD offspring cross-nursed by the C57BL dam was significantly smaller than that of the DDD offspring self-nursed by the DDD dam on the 30th, 60th, 80th, and 100th days. 5) The nursing dam strain effect on the craniofacial size of the C57BL offspring was not significant throughout the whole experimental period. The adjusted craniofacial size of the C57BL offspring cross-nursed by the DDD dam was almost the same as that of the C57BL offspring self-nursed by the C57BL dam throughout the whole experimental period. 6) The fat content of the DDD dam tended to be higher than that of the C57BL dam and the interstrain difference was closed to a significant level (P = 0.06) on the 20th day. The moisture content of the DDD dam tended to be lower than that of the C57BL dam and the interstrain difference was also significant on the 7th day (P < 0.001). Based on these findings, it can thus be concluded that the nursing dam strain effect played an important role in the postnatal somatic growth of the DDD and the C57BL offspring and the craniofacial growth and the DDD offspring.

Animals↗

PubMedDate not supplied

A longitudinal observation of the postnatal craniofacial growth in artificial monozygotic twin mice.

An artificial monozygotic twin mouse produced by bisecting a 16-cell stage embryo with a fine glass-needle and then transferring a pair of demi-embryos together into the right uterus of a pregnant recipient female mouse after a 24 hr in-vitro cultivation allowed us to examine the postnatal growth changes in monozygotic twin mice. With regard to the preimplantational growth process of the embryo, we investigated the success rate of bisecting an embryo into paired demi-embryos, the developmental ability of the bisected demi-embryo up to the early blastocyst, and the production rate of such monozygotic twin mice. The items examined in the postnatal growth process of the monozygotic twin mouse were the growth curve of the twin weight and the craniofacial size of the monozygotic twin mouse by cephalometric observations at the 3rd, 10th, 21st, 42nd, 70th, and 100th postnatal days, respectively. The following results were thus obtained. 1) The success rate of bisecting the 16-cell stage embryos into a paired demi-embryos was 86.1% (2,528/2,936). As a result, 2,301 of 2,528 paired demi-embryos could develop up to blastocysts after 24 hr of in-vitro cultivation (91.0%). 2) In addition 42 of the 394 (10.7%) recipient female mice, which had been transferred as paired demi-embryos and delivered a litter, resulted in 31 singleton mice (7.9%) or 11 paired monozygotic twin mice (2.8%), respectively. 3) The weight of each twin increased rapidly up to the 42nd day but thereafter only increased gradually up to the 100th day. The within-pair difference among each paired monozygotic twin mouse could be observed from after the 21st day until the 100th day. 4) Both the dorsoventral craniofacial size of each twin mouse and the lateral craniofacial size of each monozygotic twin mouse increased rapidly up to the 42nd day and thereafter gradually reached a plateau by the 100th day. Almost no within-pair difference was observed among each paired monozygotic twin mouse after weaning up to the 100th day. Based on these results, it is thus concluded that the craniofacial growth of each paired monozygotic twin mouse more closely resembled the growth pattern than that of the somatic growth, which thus indicated that the craniofacial growth was more greatly controlled by the genetic effect than the somatic growth. Furthermore, these findings thus suggest that an embryo bisection is an essential for producing artificial monozygotic twin mice from paired demi-embryos. Therefore, artificial monozygotic twin mice are considered to be a useful animal model for examining the effect of genetic-environment interaction on either the prenatal dento-craniofacial morphogenesis or the postnatal craniofacial growth in mice.

Animals↗