Biomedical subjects

T Maeda

Publications and source records attributed to T Maeda.

At least 685 records · Page 38Linked to original sources

PubMed1994

Distribution of free D-serine in vertebrate brains.

Free D-serine distribution in vertebrate brains was investigated. In various brain regions of the lower vertebrate species, carp, frog and chick, free D-serine levels were low. On the contrary, in the mammals, mouse, rat and bull, the contents of free D-serine were high in the forebrain (around 400 nmol/g wet weight, and the ratio of D-serine to L-serine, was D/L = 0.4), and low in the hindbrain. In developing mice, D-serine levels in the cerebrum increased with age and attained the adult level (D/L = 0.40) 8 weeks after birth. In the cerebellum and brain stem, the free D-serine levels increased with age until 2 weeks, followed by a decrease to the adult levels: the D/L ratios remained constant until 2 weeks of age, then decreased to 0.03 in the cerebellum and 0.12 in the brain stem. Free D-serine was shown not to be of microbial origin using germ-free mice. In the rat forebrain, D-serine was evenly distributed in two cerebral regions, namely frontal and occipital lobes. The D/L ratios in other regions of forebrain, hippocampus and hypothalamus, were comparable to the cerebrum (D/L = 0.4), while that in the olfactory bulb was lower (D/L = 0.12). In the rat cerebrum, the D-serine content in the grey matter was significantly higher than that in the white matter. The contents of free D-serine in bovine cerebrum and cerebellum were similar to those in other mammalian brains, but the D/L ratio for bovine cerebral grey matter was lower than that for the cerebral white matter.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Exacerbation of established collagen-induced arthritis in mice treated with an anti-T cell receptor antibody.

OBJECTIVE: To investigate the effect of T cell depletion on established collagen-induced arthritis (CIA) in mice, using monoclonal antibodies (MAb) to T cell receptor alpha/beta (TCR alpha/beta). In addition, experiments using anti-CD3 MAb were performed for comparison. METHODS: CIA was induced in male DBA/1 mice by immunizing them twice with bovine type II collagen (CII). The arthritis score and anti-CII antibody titers were examined serially. Proportions of T cells were determined by fluorescence-activated cell sorter (FACS) analysis on spleen cells or peripheral blood cells. RESULTS: When anti-TCR alpha/beta MAb was injected on the day of CII priming, no arthritis was detected in association with depressed anti-CII antibody titers. Unexpectedly, however, when MAb was given after arthritis was established, a rapid exacerbation of arthritis was observed, which resulted in ankylosis of most joints. Anti-CII antibody titers were not affected. The addition of anti-TCR gamma/delta MAb had no effect on the augmented arthritis. T cell depletion by anti-CD3 MAb during established CIA also caused an enhancement of arthritis, which was, however, weak and only transient. FACS analysis revealed that the early improvement of arthritis after the transient augmentation seen in the mice treated with anti-CD3 MAb paralleled the early recovery of alpha/beta T cells in the periphery. CONCLUSION: The present results support the concept that alpha/beta T cells, in general, may play a regulatory role in the clinical course of murine CIA after disease onset. Therefore, caution is recommended when using intensive T cell-targeted therapy in patients with rheumatoid arthritis.

Animals↗

PubMed1994

Expression of sequences homologous to HTLV-I tax gene in the labial salivary glands of Japanese patients with Sjögren's syndrome.

OBJECTIVE: To address the question of whether the human T cell leukemia virus type I (HTLV-I) gene is associated with the etiology of Sjögren's syndrome (SS). METHODS: RNA expression of HTLV-I gag, pol, env, and tax genes in labial salivary glands (LSGs) from SS patients who were seronegative for antibodies to HTLV-I was examined using reverse transcription and polymerase chain reaction techniques. RESULTS: The HTLV-I tax gene, but not the HTLV-I gag, pol, or env genes, was detected in LSG samples from 4 of 14 patients (29%). The nucleotide sequences of the HTLV-I pXIV region in these 4 patients' LSGs showed 100% homology to the HTLV-I pXIV gene from the MT-2 cell line. CONCLUSION: These findings suggest that products encoding sequences homologous to the HTLV-I pXIV gene in SS patients' LSGs might be candidates for self-antigen and/or lead to activation of autoreactive T lymphocytes through trans-acting transcriptional activation.

Base Sequence↗

PubMed1994

Substance P-immunoreactive and protein gene product 9.5-immunoreactive nerve fibres in bone marrow of rat coccygeal vertebrae.

Previous investigations have focused mainly on the nerve terminals in soft tissues surrounding the vertebrae to determine the source of spinal pain. Our study on rat coccygeal vertebrae compared intramedullary immunostaining for substance P with that of a more generally distributed neural marker, protein gene product 9.5, to suggest another source of spinal pain. Free intramedullary fibres staining for protein gene product 9.5 were rare compared with the abundant staining associated with intramedullary vessels. Shortly after entering the marrow with the nutrient vessels, substance P-immunoreactive fibres parted from the vessels and then proceeded longitudinally and terminated on the end-plates. Other (although fewer) substance P-immunoreactive fibres entered the marrow at enthetic aspects of the vertebrae. The presence of free substance P-immunoreactive fibres innervating endplates and penetrating entheses suggests that they may represent a novel source of spinal pain.

Animals↗

PubMed1994

Free fatty acid liberation and cellular swelling during cerebral ischemia: the role of excitatory amino acids.

We previously demonstrated the occurrence of cellular swelling during cerebral ischemia in vivo using microdialysis. 14C-Sucrose was pre-perfused into the extracellular space (ECS) as an ECS marker, and cellular swelling was detected as an increase in extracellular concentration of 14C-sucrose. In the present study, we examined in rats the time courses of the increase in FFA in relation to the occurrence of cellular swelling, and the role of excitatory amino acids (EAAs) in these events. A pair of microdialysis probes were placed in the hippocampus bilaterally. One probe was perfused with modified Ringer solution containing kynurenic acid (KYN, 10 mM), a broad-spectrum EAA antagonist, and the other with Ringer solution as a control. At 30 minutes after the initiation of perfusion, ischemia was induced by decapitation. The brain was subjected to microwave irradiation at 0-8 minutes after decapitation, and the FFA levels in the dorsal hippocampus were measured by high performance liquid chromatography. The time course of cellular swelling was determined in a separate group of animals using the previously described method. It was found that arachidonic and stearic acids began to demonstrate a rapid increase during the period from 1 to 2 minutes following ischemia induction. The levels of oleic and palmitic acids demonstrated similar but less marked increase. The rate of increase became less rapid after 4 minutes, suggesting a transient rapid increase superimposed on a background slow increase. The rapid increase roughly corresponded in timing to the occurrence of the early cellular swelling.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Localization of [D-Ala2]deltorphin I-like immunoreactivity in perinatal rat respiratory system.

The localization of [D-Ala2]deltorphin I, a delta-opioid receptor ligand, was studied in the lower respiratory tract of developing rats using an immunohistochemical method. [D-Ala2]-like immunoreactive cells were detected first in the principal bronchus as early as embryonic day 16. As embryos grew, positive cells became gradually visible everywhere from principal bronchi to respiratory bronchioles. The density of positive cells reached the highest level on embryonic day 21, but decreased gradually after birth. Positive cells were no longer seen on postnatal day 30 in any region of the airways. No positive cells were ever found in the trachea or alveoli of rats at any age studied. Ultrastructural examination indicated that the immunoreactive cells possessed a similar morphology to serous or Clara cells of the respiratory epithelium. Immunoreaction products tended to locate at the apical cytoplasm of positive cells. The results suggests that [D-Ala2]-like molecule(s) may be expressed transiently in serous cells or Clara cells, or both, of the rat bronchopulmonary tract. Such a molecule may act as a pulmonary growth-promoting or a differentiation-initiating factor in an early period of lung development.

Animals↗

PubMed1994

Hepatic metastasis after laparoscopic cholecystectomy for polypoid gallbladder cancer followed by radical surgery.

While laparoscopic cholecystectomy is being increasingly performed on patients with gallbladder disease, this approach in cases of polypoid lesions in the gallbladder may not always be justified. We report here a case of early development of intrahepatic metastasis after laparoscopic cholecystectomy for polypoid gallbladder cancer; wedge resection of the gallbladder bed and dissection of regional lymph nodes had to be done. When a malignancy of the gallbladder is suspected during preoperative examinations, open cholecystectomy should be done.

Adenocarcinoma, Papillary↗

PubMed1994

Effect of reserpine on 5-hydroxytryptophan (5HTP)-immunoreactive neurons in the rat brain.

By immunohistochemistry of rat brain in conjunction with a specific antibody against 5-hydroxytryptophan (5HTP), we examined immunoreactivity to 5HTP in neurons, from which 5-hydroxytryptamine (5HT; serotonin) was depleted by reserpine treatment. The distribution patterns of 5HTP-positive neurons overlapped with those of 5HT neurons. Treatment with reserpine (5 mg/kg, 90 min before death) caused a complete suppression of 5HT-positive staining, but 5HTP-immunostaining remained in perikarya of the nuclei raphe dorsalis, centralis superior and obscurus. Treatment with reserpine (25 mg/kg, 90 min before death) suppressed the 5HTP-immunoreaction in certain perikarya (e.g. of the nucleus raphe dorsalis) and fibres; however, 5HTP-immunostaining remained in perikarya of the nuclei centralis superior and raphe obscurus. This suggests that these neurons synthesize more 5HTP by a process which appears to be stimulated by reserpine.

5-Hydroxytryptophan↗

PubMed1994

Hepatic regeneration following right lobectomy: estimation of regenerative capacity.

The regenerative capacity of the liver was assessed using a volumetric method on computed tomography in 21 adults: 16 underwent a standard right hepatic lobectomy for hepatocellular carcinoma, there were hepatic metastases in 3 others, and 2 suffered from other diseases. The patients' ages ranged from 33 to 68 years with a mean age of 57.0 years. The regeneration rate was expressed as the rate of the volume increase of the remnant left lobe compared with the preoperative volume of the left lobe. A univariate regression analysis showed that the portal pressure had a highly inverse correlation with the regeneration rate of the liver (r = -0.4753, P = 0.0397), while a multiple regression analysis demonstrated the correlation between the portal pressure, age, and the regeneration rate (multiple r = 0.5640). The regeneration rate of the normal liver (97.6 +/- 53.5%) was significantly higher than that of the chronic hepatitic (43.0 +/- 40.7%), and also tended to be higher than that of the cirrhotic liver (51.5 +/- 13.2%). However, there were no differences between chronic hepatitic and cirrhotic livers. The portal pressure before hepatectomy of the normal liver (149 +/- 19 mmH2O) was significantly lower than those of chronic hepatitic (188 +/- 38 mmH2O) and cirrhotic (245 +/- 78 mmH2O) livers. We thus conclude that the regenerative capacity of the liver following a right hepatic lobectomy could be estimated on the basis of both portal pressure and age. The regenerative capacity was also influenced by underlying liver diseases.

Adult↗

PubMed1994

Dense innervation of human radicular dental pulp as revealed by immunocytochemistry for protein gene-product 9.5.

Protein gene-product 9.5 (PGP 9.5) is a novel neurone-specific protein. At light- and electron-microscopic levels, human radicular dental pulp was heavily innervated by PGP 9.5 nerve fibres. Thick nerve bundles showing intense PGP 9.5 immunoreactivity ascended in the centre of the pulp, with some nerve fibres extending from the trunk towards the peripheral pulp at regular intervals. However, the fibres did not form a plexus (of Raschkow) beneath the odontoblast cell layer. The PGP 9.5-positive nerve fibres penetrated into the predentine and dentine beyond the odontoblast cell layer where some nerves terminated. In the predentine, PGP 9.5-positive nerve fibres were densely distributed. In tangential sections along the pulpodentinal border, the nerve fibres ran in contact with odontoblast processes. Immunoelectron microscopy revealed that all nerve fibres were immunoreactive for PGP 9.5 in the radicular predentine and dentine, and terminated in contact with the odontoblast cell processes. The distribution pattern and terminal formation of predentinal and dentinal nerves were identical to those of coronal pulp, as reported previously. The dense innervation in radicular dental pulp, overlooked in previous reports, might be responsible for dentine hypersensitivity.

Adolescent↗

PubMed1994

Hepatic injury and lethal shock in galactosamine-sensitized mice induced by the superantigen staphylococcal enterotoxin B.

BACKGROUND/AIMS: Staphylococcal enterotoxin B (SEB) acts as a superantigen binding to class II major histocompatibility complex proteins, and this complex stimulates T cells. The aim of this study was to investigate the pathogenic effects of SEB on hepatic injury and lethal shock in mice. METHODS: SEB was administered to D-galactosamine (GalN)-sensitized mice, and the degree of liver injury and levels of circulating cytokines were determined. In vitro cytokine production in response to SEB was also investigated. RESULTS: Intraperitoneal administration of SEB (50 micrograms) caused lethal shock (50% mortality) associated with massive hepatic necrosis in GalN-sensitized mice, with no mortality on injection of up to 100 micrograms SEB alone. Within 2 hours after injection of SEB, serum tumor necrosis factor alpha (TNF-alpha) levels reached a peak, followed by high levels of serum interferon-gamma (IFN-gamma) up to 10 hours after injection. Passive immunization with anti-TNF-alpha/beta-neutralizing monoclonal antibody (mAb) protected GalN-sensitized mice from the lethal effects of SEB, with less protection with anti-IFN-gamma-neutralizing mAb. SEB induced the production of TNF-alpha and IFN-gamma in a dose-dependent manner from splenic mononuclear cells in vitro. CONCLUSIONS: The results show that SEB contributes to lethal shock associated with severe hepatic injury in GalN-sensitized mice and suggest that TNF-alpha and IFN-gamma produced in response to SEB may be mediators of the lethal toxicity and hepatotoxicity of SEB.

Animals↗

PubMed1994

Prevention of preeclampsia with calcium supplementation and vitamin D3 in an antenatal protocol.

OBJECTIVES: Using an angiotensin sensitivity test we carried out a prospective study in an attempt to predict the possible onset of preeclampsia and to prevent it by calcium supplementation (elemental calcium 156 or 312 mg/day per os) and treatment with vitamin D3 (0.5 micrograms/3 day per os). METHOD: We used a study design in which 666 singleton pregnant women were managed with conventional antenatal care and 210 singleton pregnant women were managed with a protocol, together with conventional antenatal care. RESULT: Of the 666 women managed conventionally, 113 (16.9%) developed preeclampsia. However, the incidence of preeclampsia in the 210 women managed on the protocol was lower, at 10.9%. CONCLUSION: Our findings indicate that this protocol for the prediction and prevention of preeclampsia is useful for pregnant women at high risk of developing preeclampsia.

Adult↗

PubMed1994

Penetration by bull spermatozoa into the zona pellucida of dead bovine oocytes recovered from frozen-thawed ovaries.

The present study was carried out to determine if the zona pellucida of dead bovine oocytes obtained from ovaries stored at -196 degrees C could be used to assess penetrability of capacitated bull spermatozoa. Follicular oocytes were recovered from bovine ovaries which were frozen slowly in a box containing dry ice, plunged into liquid nitrogen, and thawed at 37 degrees C. The dead oocytes were inseminated with various concentrations of spermatozoa preincubated for 0 to 4 h. Sperm penetration rates of the dead oocytes were significantly altered by sperm concentration and preincubation time. Dead and living oocytes matured in vitro (control) gave similar patterns of penetrability based on sperm preincubation time. When sperm concentration was increased, the rate of multiple sperm penetration into the dead oocytes also increased significantly, but the rate of penetration into living oocytes did not alter significantly. All dead oocytes from ovaries stored at -196 degrees C for 1 d to 3 mo were penetrated at similar rates by spermatozoa preincubated for 1-h. Thus, we conclude that dead follicular oocytes recovered from frozen ovaries are useful for the assessment of sperm capacitation and/or the acrosome reaction in cattle.

Journal Article↗

PubMed1994

Human cardiovascular and vestibular responses in long minutes and low +Gz loading by short arm centrifuge.

1.4 G, 1.7 G, and 2.0 G of +Gz and 60 minutes centrifugation was adopted to 20 healthy male subjects using 1.8 m radius centrifuge equipped to Nihon University School of Medicine. G was applied from lower G, considering G training effect for the subjects. Effects on performance decline and side effects of such a short-arm centrifugation were especially observed in the experiments, because this size of centrifuge could be used in space station in future for a strong countermeasure of cardiovascular deconditioning, demineralization from bone, etc. G training effect was observed same as higher and rapid G acceleration in fighter pilot. Subjects suffered from many types of discomfort; such as sensation of heaviness of diaphragm, cold sweat, nausea, irritable feeling, arrhythmia, tachycardia, rapid decrease of blood pressure, which sometimes caused interruption of G load. As 2.0 G and 60 minutes centrifugation seemed very tough load to the subjects, there should be necessary some G suit or other countermeasure, if we apply a higher G and/or longer G duration. Performance decline due to the load commonly continued for 1 hour or so. Side effects were observed in relation to neuro-vestibular, cardio-vascular, and autonomic nervous system.

Adult↗

PubMed1994

Roles of endogenous cholinergic neurons in the induction of long-term potentiation at hippocampal mossy fiber synapses.

To evaluate the functional role of endogenous acetylcholine (ACh) in the induction of long-term potentiation (LTP) at mossy fiber-CA3 synapses, the influence of cholinergic hypofunction on it was investigated. Administration of a cholinergic neurotoxin, ethylcholine mustard aziridinium ion (AF64A; 5 nmol, i.c.v.), to guinea pigs one week prior to preparing slices resulted in a significant decrease in the magnitude of LTP, associated with a significant decrease in cholineacetyltransferase (ChAT) activity and the number of ChAT immunoreactive cells in the hippocampal slices. Bath-application of a cholinesterase inhibitor, physostigmine at 0.1 microM and 10 microM, attenuated and augmented, respectively, the magnitude of LTP in slices prepared from vehicle-treated animals (naive slices), whereas that in slices prepared from AF64A-treated animals (lesioned slices) was not significantly affected by physostigmine at any concentration tested. The induction of LTP in naive slices was inhibited or facilitated by a muscarinic M1 antagonist pirenzepine (1 microM) and by an M2 antagonist AF-DX 116 (1 microM) alone, respectively, whereas that in lesioned slices was not significantly changed by either of them. Furthermore, bath-applied carbachol (CCh) at 0.01-10 microM augmented the magnitude of LTP in lesioned slices, whereas the induction of LTP in naive slices was inhibited and facilitated by CCh at 0.01-0.1 microM and 1-10 microM, respectively, as reported previously. Such an augmentation of LTP by CCh was reversed by pirenzepine, but not by AF-DX 116. These observations suggest that AF64A induces the defect in ACh release and the hypofunction of M2 receptors, but not of M1, at least during the induction of LTP at mossy fiber-CA3 synapses.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Inhibitory influence via 5-HT3 receptors on the induction of LTP in mossy fiber-CA3 system of guinea-pig hippocampal slices.

The effects of 5-HT3-receptor-related agents on long-term potentiation (LTP) in the mossy fiber-CA3 system were studied in guinea pig hippocampal slices. 5-HT3 receptor agonists, 1-(m-chlorophenyl)-biguanide (mCPBG) and 2-methyl serotonin (2-Me-5-HT) significantly attenuated the magnitude of LTP of the population spike at 0.3-1 microM and at 10 microM respectively. At these doses neither of these drugs did affect the amplitude of the population spike (PSA) evoked by test stimuli in the absence of tetanic stimulation. The attenuating effect of mCPBG on LTP was reversed by the GABAA receptor antagonist bicuculline. On the other hand, 5-HT3 receptor antagonists ondansetron and granisetron significantly augmented the magnitude of LTP at 1-3 microM and at 0.1-0.3 microM, respectively, without changes in PSA before tetanus. The augmenting effect of granisetron on LTP was partially but significantly reversed by the muscarinic receptor antagonist atropine. These findings suggest that the induction of the LTP in the mossy fiber-CA3 system is inhibited by an activation of 5-HT3 receptors through the facilitation of GABAergic neurons (GABAA receptors) and the inhibition of cholinergic neurons (muscarinic receptors).

Animals↗

PubMed1994

Demonstration of [D-Ala2]deltorphin I-like immunoreactivity in mucosal epithelial cells of the rat gastrointestinal tract.

Using a specific antiserum to [D-Ala2]deltorphin I (DADTI), a delta-opioid receptor ligand, the localization of positive structures was studied in rat gastrointestinal tract by immunocytochemistry. Immunoreactive staining was not detected in the stomach, colon, or neuronal elements of any gastrointestinal tissue. However, positive cells were distributed in the mucosal epithelium of the small intestine, including the duodenum, jejunum, and ileum. The density of positive cells was highest at a proximal part of the jejunum and was gradually decreased toward the duodenum or the distal end of the intestine. These positive cells had spindle-like somata that tended to locate more closely to the lumen compared with nonimmunoreactive cells. Some of the positive cells extended cytoplasmic basal processes toward the lamina propria. Immunoelectron microscopy revealed that positive reaction products occurred within the secretory granules as well as in the cytoplasm. Because these positive granules were frequently observed in the apical cytoplasm beneath the microvilli, it is suggested that the DADTI-like molecule(s) may be secreted to the lumen.

Amino Acid Sequence↗

PubMed1994

Monoamine oxidase: distribution in the cat brain studied by enzyme- and immunohistochemistry: recent progress.

Localization of MAO-containing neurons, fibers and glial cells has been described by recent progress in MAO histochemistry and immunohistochemistry. It does not necessarily correspond to those containing monoamines. MAO-A is demonstrated in many noradrenergic cells, but it is hardly detectable in DA cells. Increase of 5-HT and DA concentration after inhibition of MAO-A indicates the possible existence of MAO-A in such neuronal structures. MAO-A is also undetectable in neurons containing 5-HT, a good substrate for MAO-A. These neurons contain MAO-B. There still remain contradictions to be solved in future. MAO is present in astroglial cells, in which monoamines released in extracellular space may be degraded. In glial cells, MAO may also play a role to regulate concentration of telemethylhistamine and trace amines. Such cells appear to transform MPTP to MPP+, a neurotoxin for nigral DA neurons.

Animals↗