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Biomedical subjects

H Tojo

Publications and source records attributed to H Tojo.

At least 91 records · Page 5Linked to original sources

Targeted disruption of the neurotrophin-3 gene with lacZ induces loss of trkC-positive neurons in sensory ganglia but not in spinal cords.

We have replaced the NT-3 gene with Escherichia coli-derived lacZ gene by means of homologous recombination in embryonic stem cells and thus produced null mutant mice. Mice homozygous for this mutation developed to birth, but most of them could not suck well and died within 2 days after birth. The surviving homozygous mutant mice displayed movement disorder similar to ataxia. The expression of lacZ was widely distributed in the target tissues of peripheral nerves, spinal motor neurons, lumbar dorsal root ganglia and trigeminal ganglia during the prenatal periods. A neuroanatomical examination revealed that there was marked cell reduction present in trigeminal and lumbar dorsal root ganglia in the developing homozygous mutant mice. In these tissues, the expression of trkC, a high-affinity receptor for NT-3, was markedly reduced. In contrast, we did not find any morphological abnormalities, significant cell loss or decreased levels of trkC expression in the motor neurons present in the ventral horn of the spinal cord. These results indicate that the absence of the NT-3 gene leads to a defect in the sensory nervous system, but it may be complemented by other neurotrophins in the motor nervous system during the development.

Animals↗

Dietary alpha-linolenate/linoleate balance influences learning and memory in the senescence-accelerated mouse (SAM).

The senescence-accelerated mouse (SAMP8) is a model of age-related deterioration of memory and learning ability. A semipurified diet supplemented either with safflower oil (rich in linoleate) or with perilla oil (rich in alpha-linolenate) was fed to SAMP8 mouse dams and their pups. The offspring (males from several mothers) at 28 weeks of age were used for behavioral tests. The proportions of n-3 and n-6 highly unsaturated fatty acids in brain phospholipids reflected the n-3/n-6 balance of the diets. The learning and memory abilities of the two dietary groups were tested with the Sidman active avoidance task and the light and dark discrimination learning test. The group given perilla oil showed much greater improvement in learning in the Sidman active avoidance task than did the group fed safflower oil. In the light and dark discrimination learning test, the total number of responses to positive and negative stimuli was lower in those fed perilla oil, and their responses to positive stimuli were higher than to negative stimuli after the 10th session. Consequently, the correct response ratios of discrimination were higher in the perilla oil group than in the safflower oil group. In the open field test, the total amount of locomotor activity during 5 min was lower in the perilla oil group at 7 months of age than in the group fed safflower oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

Expression of whey acidic protein (WAP) genes in tissues other than the mammary gland in normal and transgenic mice expressing mWAP/hGH fusion gene.

Whey acidic protein (WAP) is a major whey protein secreted in rodents' milk. Murine WAP (mWAP) genes have been assumed to be expressed solely in the mammary gland. However, several heterologous genes fused with the mWAP promoter and artificially introduced into animal genomes as transgene were expressed not only in the mammary gland but also in other tissues as well. In the present study, we investigated, by means of the reverse transcription polymerase chain reaction (RT-PCR), the patterns of expression of endogenous WAP genes in tissues of normal mice and in transgenic mice carrying hGH gene coupled to the mWAP promoter sequence. The results revealed that the genes driven by the mWAP promoter, regardless of whether they are endogenous genes or transgenes, were transcribed in a variety of tissues other than the mammary gland of lactating normal female mice, although the expression levels are generally low. The expression of WAP genes in the cerebrum and the liver is regulated, as in the mammary gland, according to the reproductive stages. However, the tissue distribution of endogenous WAP gene expression in mature virgin transgenic female mice was the same as that in lactating normal female mice.

Animals↗

Autonomic hyperreflexia during labour.

We present two cases of automatic hyperreflexia (AH) during labour in women with spinal cord damage, in whom AH developed before and after delivery. The AH was successfully controlled using epidural anaesthesia in Case #1, but failed in Case #2. The blood pressure was controlled with nicardipine. However, overdose of nicardipine produces vasodilation and its side effects include headache, flushing and palpitation similar to AH. Considering these effects, we recommend epidural anaesthesia to control AH, because epidural anaesthesia does not only reduce BP, but also blocks the noxious stimuli and relieves the symptoms of AH. Our experience suggests that the epidural catheter can be placed two to three weeks before the date of predicted childbirth, because the onset of labour in a patient with spinal cord damage is difficult to predict and can proceed very rapidly. Also, the epidural catheter is available after the delivery. We recommended the epidural catheter is maintained for 24-48 hr postpartum.

Adult↗

Oxygen transport and hemodynamics during retrograde whole-body perfusion.

The changes in oxygen transport and hemodynamics during retrograde whole-body extracorporeal perfusion (retro-ECC) were studied in six mongrel dogs. Oxygen consumption during retro-ECC, in which the blood flow rate was set at 25% and 50% of the flow during antegrade extracorporeal perfusion (ante-ECC), respectively, was relatively high compared with that during ante-ECC. These changes were caused by an increase in the oxygen extraction ratio to 71.5% +/- 8.2% and 51.2% +/- 12.4% during retro-ECC/25% and retro-ECC/50%, respectively. Thus, tissue perfusion was apparently well maintained by retrograde perfusion on the basis of the oxygen transport data. However, central venous pressure increased markedly to 29.5 +/- 11.6 mmHg and 56.2 +/- 24.5 mmHg during retro-ECC/25% and retro-ECC/50%, respectively, because of massive venous congestion caused by insufficient arterial return of perfused blood. The great venous compliance and increased systemic vascular resistance were the main causes of circulatory failure during retro-ECC. The risk of serious complications owing to the venous congestion must be considered during retrograde perfusion, especially during the clinical application of retrograde cerebral perfusion.

Animals↗

Effects of matrix proteins and heparin-binding components in fetal bovine serum upon the proliferation of ectoplacental cone cells in mouse blastocysts cultured in vitro.

Trophoblastic invasion of the endometrium is among the events that are crucial for successful implantation and hemochorial placentation. To understand the mechanism underlying the trophoblastic invasion, we investigated effects of fibronectin substratum and heparin-binding components in fetal bovine serum (FBS) upon trophoblast and ectoplacental cone (EPC) cells derived from mouse blastocysts produced by IVF and cultured in vitro. The results demonstrated that 1) in these blastocysts, contact of EPC cells with fibronectin-coated glass substratum in the presence of FBS triggered an outburst of cell proliferation with the eventual differentiation of the EPC cells into secondary giant trophoblast cells and 2) frequencies of blastocysts that exhibited EPC cell proliferation significantly increased if FO medium (modified Eagle's minimum essential medium) was supplemented with FBS depleted of heparin-binding substances (H-FBS). One possible interpretation of the effect of H-FBS is that free fibronectins or related substances in the serum might interfere with EPC cell proliferation, for which the presence of substratum-bound fibronectin is essential. Alternatively, the serum might contain heparin-binding competitive inhibitors of yet unidentified growth factor(s) necessary for EPC cell proliferation.

Animals↗

Effects of orally administered liposomes with soybean-derived sterols and their glucosides on rat body weight.

The effects on Wistar rat body weight were examined after a single subcutaneous (s.c.) or oral (p.o.) administration of dipalmitoylphosphatidylcholine (DPPC) liposomes composed of soybean-derived sterols (SS) and their glucosides (SG) with or without entrapping recombinant human erythropoietin (Epo) for 1 week. Body weight increased significantly after both types of administration compared with the control groups irrespective of the existence of Epo. The neutral lipid concentration in plasma increased with the increase in body weight whereas the total contents of cholesterol and high density lipoprotein cholesterol in the plasma did not change significantly. The SS and SG suspensions following p.o. administration, however, did not alter the body weight. These findings suggest that liposomal SS and SG may be absorbed through the intestinal membrane and induce a change in the uptake of lipid, in contrast to the suspension state. SS in liposomes significantly increased body weight more than SG after p.o. administration.

1,2-Dipalmitoylphosphatidylcholine↗

Molecular analysis of the human fetal-to-adult globin switching.

Hereditary persistence of fetal hemoglobin (HPFH) is a condition characterized by continued expression of the gamma-globin gene in adult life. Analysis of a Japanese HPFH family had revealed that the C-T transition at position -114 within the distal CCAAT box of the gamma-globin gene associated with the HPFH allele. In the vicinity of the distal CCAAT box, other two mutations (-117 C-T, 13 bp del) had been identified in individuals with a HPFH phenotype. Functional analysis of these mutant promoters in erythroid cell lines suggested that the distal CCAAT box works positively in the fetus but negatively in the adult on the expression of the gamma-globin gene. Further study on transgenic mice showed that the -114 mutation was responsible for the elevated expression of the gamma-globin gene in the adult. To elucidate the molecular mechanism underlying the persistent expression of the gamma-globin genes associated with the HPFH mutations, interaction of the mutant promoters with nuclear factors was analyzed. Relevance of the nuclear factor, NFE3, to the gamma-globin regulation was suggested by the affected binding of NFE3 to the altered distal CCAAT boxes with HPFH mutations (-117, -114, 13 bp del).

Adult↗

D-amino-acid oxidase is confined to the lower brain stem and cerebellum in rat brain: regional differentiation of astrocytes.

Based on enzymatic activity, the localization and the identification of D-amino-acid oxidase-containing cells in rat whole brain was systematically studied in serial fixed sections. The oxidase activity was absent or scarce in the forebrain, was confined to the brain stem (midbrain, pons and medulla oblongata) and cerebellum, and its localization was extended to the spinal cord. In the brain stem the oxidase was mainly localized in the tegmentum, particularly in the reticular formation. The intense oxidase reactions were present in the red nucleus, oculomotor nucleus, trochlear nucleus, ventral nucleus of the lateral lemniscus, dorsal and ventral cochlear nuclei, vestibular nuclei, nuclei of posterior funiculus, nucleus of the spinal tract of the trigeminal nerve, lateral reticular nucleus, inferior olivary nucleus, and hypoglossal nucleus. In the cerebellum the activity in the cortex was much more intense than that in the medulla. In all the fields described above, the oxidase-containing cells were exclusively astrocytes including Bergmann glial cells, and neither neuronal components, endothelial cells, oligodendrocytes nor ependymal cells showed oxidase activity. These results indicated that the astrocytes regionally differentiated into two distinct types, one of which expressed oxidase in the midbrain, rhombencephalon and spinal cord, and the other which did not in the forebrain. The localization of the oxidase was inversely correlated with the distribution of free D-serine in mammalian brains (Nagata, Y., Horiike, K. and Maeda, T., Brain Res., 634 (1994) 291-295). Based on the characteristic localization of the oxidase-containing astrocytes, we discussed the physiological role of the oxidase.

Animals↗

Enhanced expression of group II phospholipase A2 in human hepatocellular carcinoma.

Enzyme activity, protein contents, and mRNA contents of group II phospholipase A2 (PLA2) in hepatocellular carcinoma (HCC) surgically obtained from 8 patients were compared with those in either its neighboring liver tissues or control liver tissues. The PLA2 specific activity towards the mixed micelles of 1-palmitoyl-2-oleoyl-phosphatidylglycerol and cholate was significantly greater in the tumor tissues (6.62 +/- 1.46 nmol/min/mg) than those in the surrounding liver tissues (1.33 +/- 0.22 nmol/min/mg) and controls (0.43 +/- 0.04 nmol/min/mg). The results of immunoblot analysis using a specific anti-human group II PLA2 antibody and of Northern blot analysis using a human group II PLA2 cDNA as a probe demonstrated that group II PLA2 was responsible for the increased enzyme activity. The contents of immunoreactive group II PLA2 in the tumor tissues (8.81 +/- 1.24 ng/mg) were significantly higher than those in the surrounding liver tissues (1.74 +/- 0.27 ng/mg); those in the control tissues were below the analytical range of the method used. The group II PLA2 mRNA was also significantly increased in the tumor tissues, compared with that in the surrounding liver tissues, whereas it was not detectable in the controls. This indicates that group II PLA2 in HCC is induced at the pretranslational level.

Carcinoma, Hepatocellular↗

Production of human protein disulfide isomerase by Bacillus brevis.

Human protein disulfide isomerase (PDI; EC 5.3.4.1) was expressed and secreted into the culture medium using Bacillus brevis as host and pNU200 which codes the promoter and signal sequence of major cell wall protein of B. brevis as vector. The accumulation of recombinant human PDI (rhPDI) reached about 5 mg l-1 in the late exponential phase of the bacterial growth. The purified rhPDI was found to be exactly processed at the carboxyl terminus of the signal sequence. It was as active as natural PDI derived from human placenta as determined by its ability to reactivate scrambled ribonuclease that was a fully oxidized mixture containing randomly formed disulfide bonds. The activity was significantly accelerated in the presence of dithiothreitol or a mixture of reduced and oxidized glutathione. These indicate that the characteristics of rhPDI are similar to those reported for mammalian PDI and that it can be used for refolding inactive proteins having incorrect disulfide bonds.

Amino Acid Sequence↗

Melanocytes fail to survive in hair bulbs of the Shiba goat (Capra hircus) with the dominant black-eyed white phenotype.

Dominant black-eyed white phenotypes are one of the most commonly observed traits in domestic animals. Their genetic control mechanisms, however, have not been elucidated. As the first step to approach the problem, we examined histologically the patterns of the distribution of pigment cells in Shiba goats (two each of day-73-postcoitum and day-112-postcoitum fetuses, and a 15-week-old kid) with the dominant black-eyed white phenotype. Melanocytes were present and fully pigmented in the choroid and the sclera of eyes, as well as in dorsal skin epidermis of the fetuses and of the kid. Melanocytes were also found in approximately 6% of the hair bulbs in the fetal dorsal skin, while the rest (94%) lacked them. Hair follicles of the kid did not harbor melanocytes except for some in the early anagen stage. The results suggest that the survival of melanocytes was inhibited specifically in the hair follicles of the Shiba goat with the dominant black-eyed white phenotype and that the ostensibly similar phenotypes in the Shiba goat and in the S1 or W mutants of the mouse, where melanocytes die en route to the hair bulbs, are regulated by different mechanisms.

Animals↗

Increased group II phospholipase A2 in colonic mucosa of patients with Crohn's disease and ulcerative colitis.

The immunochemical protein content of group II phospholipase A2 (PLA2) and PLA2 enzymatic activity were measured for colonic mucosal biopsy samples obtained from patients with either Crohn's disease of the colon or ulcerative colitis, and control patients without inflammatory bowel disease. Immunoreactive group II PLA2 (IR-PLA2 II) content and PLA2 activity in actively inflamed colonic mucosa of Crohn's disease patients were significantly higher than those in inactively inflamed mucosa of Crohn's disease patients and the colonic mucosa of controls. IR-PLA2 II content and PLA2 activity in severely inflamed mucosa of ulcerative colitis patients were significantly higher than those in the colonic mucosa of the controls. Mucosal PLA2 enzymatic activity was closely correlated with mucosal IR-PLA2 II content in patients with Crohn's disease and ulcerative colitis. These results suggest that an increase in PLA2 enzymatic activity in inflamed colonic mucosa of Crohn's disease and ulcerative colitis was mainly attributed to increased protein content of group II PLA2, and that an increase in mucosal group II PLA2 may be involved in the pathogenesis of intestinal inflammation of Crohn's disease and ulcerative colitis.

Adolescent↗

Changes in endogenous growth hormone secretion and onset of puberty in transgenic rats expressing human growth hormone gene.

A chimeric gene comprising murine whey acidic protein (mWAP) and human growth hormone (hGH) was used to produce transgenic rats that express hGH and secrete it into the blood. Two lines of transgenic rats carrying the mWAP/hGH construct were established: Line 1 was characterized by relatively high levels of serum hGH, and Line 2 had relatively low levels. The secretory profiles of rat GH (rGH) as well as hGH, the transgene product, were obtained in transgenic males and females of Line 2; both hGH and rGH serum levels were flattened with no episodic fluctuations, and the overall mean concentration of rGH was significantly lower than in normal littermates. Although the animals of Line 1 showed an accelerated increase in growth rate, those of Line 2 did not. Nevertheless, the onset of puberty in females, as assessed by vaginal opening and occurrence of first ovulation, advanced by 7-8 days in both Lines of animals. Accordingly, the body weight at puberty of Line 2 transgenic females was much lower than that of normal littermates, indicating that continuous hGH expression could induce precocious puberty without enhancing the growth rate.

Age Factors↗

[Increased serum alkaline phosphatase induced by DT-5061, an oral contraceptive, in rats].

DT-5061, a steroid oral contraceptive which contains norethisterone (NET) and ethinyl estradiol (EE) in a ratio of 100:7, was administered orally to rats for 14 days in order to investigate a possible origin of the increased serum alkaline phosphatase (ALP). Increased serum total ALP was noted in rats receiving DT-5061 at 5.35 mg/kg/day or EE at 0.35 mg/kg/day. Electrophoresis of serum ALP revealed that both liver and bone-type ALP isozymes were increased in the DT-5061 5.35 mg/kg and EE 0.35 mg/kg groups, and the ratio of increase in the liver-type was greater than that in the bone-type although the increase in concentration of the bone-type was greater as compared to the liver-type. ALP level in the liver was elevated together with an increase in liver weight, consistently with the increased serum liver-type isozyme. However, neither histological changes indicative of cholestasis nor increase in serum leucine aminopeptidase, bilirubin, GOT or GPT were seen. No changes were observed in bone ALP activity; hence inconsistent with the increased serum bone-type isozyme. From these results, it is considered that the increased serum ALP induced by this drug was due to the increased liver-type isozyme induced in the liver and to the increased bone-type isozyme, and among the ingredients of this oral contraceptive, EE was mainly involved in the increased serum ALP induced by this drug.

Administration, Oral↗

[Effects of adrenalectomy on the increased serum alkaline phosphatase activity induced by DT-5061, an oral contraceptive, in rats].

DT-5061, a steroid oral contraceptive which contains norethisterone (NET) and ethinyl estradiol (EE) was administered orally to adrenalectomized rats for 3 days to investigate involvement of the adrenals in the increased serum alkaline phosphatase (ALP). In addition, corticosterone or aldosterone were administered to the adrenalectomized rats to examine their effects on serum ALP. Increases in serum total ALP, liver-type and bone-type ALP isozymes were observed in rats with intact adrenals following administration of DT-5061, but these responses were not noted in adrenalectomized rats. Increases in liver weight and ALP activity in the liver after administration of the drug were reduced but not abolished in the adrenalectomized rats. The adrenalectomized rats receiving corticosterone showed increases in serum total ALP, liver-type ALP isozyme and liver weight but did not exhibit any increase in bone-type ALP isozyme. On the other hand, aldosterone did not increase and even reduced serum ALP although ALP activity in the liver was increased in the adrenalectomized rats.

Adrenal Glands↗

[A case of vertebral metastasis revealed by incomplete spinal analgesia for cesarean section].

A 36-year-old woman was scheduled for Cesarean section under spinal anesthesia. She was a carrier of hepatitis-B-virus and diabetic. She was complaining of low back pain. Spinal anesthesia was performed in the left lateral decubitus position. Because lumbar puncture in the midline was difficult, left paramedian approach was tried. Then she began to complain of right leg pain. Another attempt was made at other site, but her pain was not relieved. After confirming drop of blood-tinged cerebrospinal fluid, 0.3% dibucaine 2.0 ml was injected. Sensory anesthesia was assessed by pin-prick, but anesthesia was not effective. Then epidural catheter was inserted at Th12-L1 using median approach. She received 1.0% lidocaine 15 ml. However, sensory anesthesia was insufficient (Th4-Th12). Therefore O2-N2O was administered in addition to regional anesthesia. After the delivery, she still complained of low back pain. Later examination revealed metastatic bone tumor of L2 from hepatoma. This case suggests that in a patient with such incomplete spinal or epidural anesthesia and neurological finding, vertebral metastatic tumor should be ruled out.

Adult↗