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Biomedical subjects

M Kawata

Publications and source records attributed to M Kawata.

At least 19 recordsLinked to original sources
PubMed1992

Development of peptide- and tyrosine hydroxylase-containing neurons in the fetal spinal cord transplanted into the anterior chamber of the eye of adult rats.

Fetal rat spinal cord transplanted into the anterior chamber of the eye of an adult rat was immunohistochemically stained using antisera to substance P (SP), neuropeptide Y (NPY), methionine-enkephalin (ENK), vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP) and tyrosine hydroxylase (TH), and distributional changes of peptide- and enzyme-containing neurons 1, 2 and 4 weeks after transplantation were investigated. To examine the effect of colchicine on immunoreactivity, unilateral eyes of these adult host rats received intraocular colchicine treatment. Without colchicine treatment, numerous SP- and CGRP-immunoreactive (IR) neurons were observed in the graft 1 week after transplantation, and their immunoreactivity gradually decreased up to 4 weeks after transplantation. NPY-, ENK-and VIP-IR neurons first appeared in the graft 2 weeks after transplantation. Four weeks after transplantation, the immunoreactivity of NPY and ENK decreased significantly, whereas VIP-IR neurons showed the same intensity as that observed at 2 weeks after transplantation. TH-IR neurons, on the other hand, were seen at every stage, but their immunoreactivity was constant all the time. After colchicine treatment, the number of SP-, NPY-, ENK- and CGRP-IR neurons appeared to increase, while that of VIP- and TH-IR neurons did not change significantly. The distribution patterns of the peptide- and enzyme-containing fibers differed from each other. In the analysis of serial sections stained with 5 peptides (SP, NPY, ENK, VIP, CGRP), fibers containing these peptides were found to be densely accumulated in specific areas of the transplanted spinal cord. The present findings demonstrated that most of the peptide- and enzyme-containing neuron systems in the transplanted spinal cord showed similar distribution patterns and development to those in the normal spinal cord, but that some displayed different distribution.

Animals↗
PubMed1992

Nuclear localization of estrogen receptor-immunoreactivity in the preoptic area of female rats and its reduction by intraventricular colchicine treatment.

The subcellular localization of estrogen receptor (ER) was investigated in the preoptic area of ovariectomized female rats by electron microscopic immunohistochemistry, using a monoclonal antibody to ER. ER-immunoreactivity was localized in the nuclei of neurons of the periventricular preoptic nucleus (Pe) and the medial preoptic area (MPA). ER-immunoreactivity had a speckled pattern in the nucleus, but was not observed in the nucleolus or cytoplasm. After intraventricular colchicine treatment, ER-immunoreactivity within the nucleus was reduced drastically in neurons of the Pe and the MPA. The possible mechanism by which colchicine alters ER-immunoreactivity is mentioned.

Animals↗
PubMed1992

Changes of chemoarchitectural organization of the rat spinal cord following ventral and dorsal root transection.

Time-related changes in the distribution of chemical messengers in the rat spinal cord following the transection of dorsal and ventral roots were observed by using immunohistochemistry for the following antigens: microtubule-associated protein 2 (MAP2), calcitonin gene-related peptide (CGRP), substance P (SP), galanin (Gal), Met-enkephalin (Enk), neuropeptide Y (NPY), and serotonin (5-HT). To investigate dendrocytoarchitectonic organizational changes, morphometric analyses were performed on both the gray and the white matter of tissue samples stained with MAP2 antiserum. A significant reduction in the area of gray matter on the lesioned side was seen from 1 to 24 weeks postoperation, and progressive changes in the shape of the gray matter were also observed. CGRP-immunoreactive fibers were reduced in number in the posterior horn after root transection, except in the lateral part of lamina I. In contrast, CGRP immunoreactivity in the anterior horn cells of the ipsilateral side was increased early after transection, but later it progressively decreased. Root transection also caused significant reduction in the number of SP-immunoreactive fibers in the posterior horn, but no changes were seen in the anterior horn. Gal immunoreactivity was also affected by root transection, and it changed in a similar way to CGRP immunoreactivity. 5-HT-immunoreactive fibers were increased in the posterior horn after transection, and later decreased. In the anterior horn, there were no changes in the intensity or distribution pattern of 5-HT-immunoreactive nerve fibers following root transection. Enk and NPY immunoreactivity in the anterior and posterior horns was not affected by root transection up to 24 weeks postoperative. These results show that spinal root transection caused significant changes in the chemoarchitectural organization of nerve fibers containing certain types of chemical messengers, such as CGRP, SP, Gal, and 5-HT, in addition to altering dendritic geometry in the spinal cord.

Animals↗
PubMed1992

The geranylgeranyl moiety but not the methyl moiety of the smg-25A/rab3A protein is essential for the interactions with membrane and its inhibitory GDP/GTP exchange protein.

The smg-25A/rab3A protein (smg p25A), a member of the small GTP-binding protein superfamily, has a C-terminal structure of Cys-Ala-Cys which is post-translationally processed: both cysteine residues are geranylgeranylated followed by the carboxyl methylation of the C-terminal cysteine residue. We reported previously that this posttranslational processing is essential for the interactions of smg p25A with membrane and its inhibitory GDP/GTP exchange protein, named smg p25A GDP dissociation inhibitor (GDI). In this study, we examined which posttranslational modification of smg p25A is necessary for these interactions. The smg p25A which was not posttranslationally processed was produced in Escherichia coli and purified. This protein was then geranylgeranylated at both of the 2 cysteine residues by use of a bovine brain geranylgeranyltransferase in a cell-free system (recombinant smg p25A-GG). By use of this recombinant smg p25A-GG, its membrane-binding activity and its sensitivity to smg p25A GDI were compared with those of the fully posttranslationally processed form of bovine brain smg p25A (smg p25A-GG-Me) and the posttranslationally unprocessed form of bacterial smg p25A (recombinant smg p25A). The membrane-binding activity and sensitivity to smg p25A GDI were similar between the recombinant smg p25A-GG and smg p25A-GG-Me, although recombinant smg p25A lacked both activities. These results indicate that the geranylgeranyl moiety of smg p25A is essential and sufficient for its interactions with membrane and smg p25A GDI and that the methyl moiety is not essential for these interactions.

Amino Acid Sequence↗
PubMed1992

Semi-quantitative analysis of the effects of estrogen on CGRP- and methionine-enkephalin-immunoreactivity in the periventricular preoptic nucleus and the medial preoptic area of female rats.

The effects of 17 beta-estradiol (E2) on calcitonin gene-related peptide (CGRP)- and methionine-enkephalin (Met-Enk)-immunoreactive (IR) nerve fibers in the periventricular preoptic nucleus (Pe) and the medial preoptic area, including the medial preoptic nucleus (MPN), of the female rat were studied semi-quantitatively by using a computer-based image analysis system. The area occupied by CGRP- and Met-Enk-IR fibers was significantly increased in the Pe and the MPN after 28-day exposure to E2. Computer-based analysis of CGRP- and Met-Enk-IR fibers in an area of 50-microns intervals from the wall of the third ventricle showed a low flat histogram pattern in ovariectomized rats, but E2 treatment caused a diphasic pattern, corresponding to the Pe and the MPN, respectively. Since the Pe and the MPN contain a high population of estrogen receptors, it is suggested that E2 may have an influence on the neuronal configuration of afferent fibers to these areas.

Animals↗
PubMed1992

Preparation and evaluation of Eudragit gels. III: Rectal gel preparations for sustained release of pentoxifylline.

A novel method was established for the preparation of Eudragit S, Eudragit L, and Eudispert high-viscosity (hv) hydrogel and xerogel preparations containing a medicinal component such as pentoxifylline (an agent that improves cerebral microcirculation). A significant correlation was found between the in vitro mean dissolution time and the in vivo mean residence time of pentoxifylline after rectal administration of these preparations in rabbits. Staying properties of the hydrogel and xerogel preparations in the lower part of the rectum were compared with those of polyethylene glycol 2000 and Witepsol S-55 suppositories in rats, with water-insoluble dye. Eudispert hv hydrogel and xerogel preparations have excellent staying properties in the rectum. The efficacy of Eudispert hv xerogel preparations may be reduced by first passage through the liver after oral administration.

Acrylic Resins↗
PubMed1992

Preparation and evaluation of Eudragit gels. IV: Rectal gel preparations for sustained release and avoidance of first-pass metabolism of propentofylline.

Formulations of a high-viscosity acrylic resin gel (Eudispert hv) containing propentofylline, a new cerebral microcirculation-improving agent, were prepared and tested for avoidance of the first-pass metabolism of propentofylline through the liver and for sustained release of propentofylline. The absolute bioavailability of propentofylline after oral administration was only 4% in rabbits. The relative bioavailabilities of propentofylline from polyethylene glycol (M(r), 2000) and Witepsol H-15 suppositories were approximately 8- and 16-fold, respectively, compared with oral administration. Furthermore, the absolute bioavailability of propentofylline from Eudispert hv hydrogel and xerogel preparations was approximately 100%. The results indicate that, in principle, drug loss caused by first-pass metabolism may be avoided completely by placing Eudispert hv hydrogel and xerogel formulations in the lower part of the rectum for long periods.

Acrylic Resins↗
PubMed1992

Time-related changes in the labeling pattern of motor and sensory neurons innervating the gastrocnemius muscle, as revealed by the retrograde transport of the cholera toxin B subunit.

Morphological changes in the motor and sensory neurons in the lumbar spinal cord and the dorsal root ganglia were investigated at different survival times following the injection of the B subunit of cholera toxin (CTB) into the medial gastrocnemius muscle. Unconjugated CTB, visualized immunohistochemically, was found to be retrogradely transported through ventral and dorsal roots to motor neurons in the anterior horn, each lamina in the posterior horn, and ganglion cells in the dorsal root ganglia at L3-L6. The largest numbers of labeled motor neurons and ganglion cells were observed 72 h after the injection of CTB. Thereafter, labeled ganglion cells were significantly decreased in number, whereas the amount of labeled motor neurons showed a slight reduction. Motor neurons had extensive dendritic trees filled with CTB, reaching lamina VII and even the pia mater of the lateral funiculus. Labeling was also seen in the posterior horn, but the central and medial parts of laminae II and III had the most extensively labeled varicose fibers, the origin of which was the dorsal root ganglion cells. The results indicate that CTB is taken up by nerve terminals and can serve as a sensitive retrogradely transported marker for identifying neurons that innervate a specific muscle.

Animals↗
PubMed1992

Expression of a human multidrug resistance gene in human ovarian carcinoma cell lines.

To investigate the possible role of the multidrug resistance phenotype to chemoresistance in human ovarian carcinoma, we have analyzed human multidrug resistance gene (mdr 1) expression in 8 human ovarian adenocarcinoma cell lines. An increase in P-glycoprotein level specific to multidrug-resistant tumor cells was not apparently associated with the increase in resistance to vincristine (VCR) or doxorubicin (Adriamycin). Mdr 1 transcripts (4.5 kilobases) were observed in the RNA preparation obtained from only one cell line (SHIN-3) that showed the highest resistance to both drugs in vitro and in vivo. No cell lines showed mdr 1 DNA amplification. These results suggest that the insensitivity of human ovarian carcinoma to chemotherapy could be partly explained by the expression of mdr 1.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

Immunohistochemical and enzymehistochemical studies of peptidergic, aminergic and cholinergic innervation of the lacrimal gland of the monkey (Macaca fuscata).

The distribution of nerve fibers containing peptides which include calcitonin gene-related peptide (CGRP), substance P (SP), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) and enzymes of tyrosine hydroxylase (TH) and acetylcholinesterase (AchE) in the lacrimal gland of the monkey (Macaca fuscata) was studied using immunohistochemical and enzymehistochemical methods. We also examined the trigeminal ganglion (TG) and superior cervical ganglion (SCG) using the same methods. All peptide- and enzyme-containing nerve fibers examined in this study were present in the lacrimal gland and a consistent distribution pattern for each substance was found. CGRP-immunoreactive (IR) nerve fibers were mainly distributed around the blood vessels in the interlobular connective tissue. The distribution pattern of SP-IR nerve fibers was similar to that of CGRP-IR nerve fibers, but they were much less in number. NPY-IR nerve fibers were observed mostly around the blood vessels and occasionally in the interstitial stroma between the acini. Numerous VIP-IR nerve fibers were found surrounding the acini, ducts and blood vessels. TH-IR nerve fibers were also been around the blood vessels and in the interstitial stroma between the acini, as were NPY-IR fibers. The highest concentration of acetylcholinesterase (AchE)-positive nerve fibers was present in the acini, ducts and blood vessels, showing a similar distribution to VIP-IR fibers. In the TG, 50% of medium and 30% of small ganglion cells were CGRP-IR cells, while 20% of medium and 25% of small ganglion cells were of the SP-IR types.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase↗
PubMed1992

Estrogen as a growth factor to central nervous cells. Estrogen treatment promotes development of acetylcholinesterase-positive basal forebrain neurons transplanted in the anterior eye chamber.

In a previous report, we demonstrated in vivo ameliorating effects of conjugated estrogen in women suffering from senile dementia-Alzheimer's type. To investigate the effects of estrogen on the growth of cholinergic neurons, the present study was performed using rat cholinergic tissue implanted into the anterior chamber of the eye. Fetal diagonal band tissue containing cholinergic neurons was grafted into the anterior eye chamber of adult female rats that had either been treated or not with 2 mg estradiol valerate injected every 3 days after oophorectomy. Two and four weeks after transplantation, the axonal and/or dendritic growth of cholinergic neurons in the graft was studied using acetylcholinesterase histochemistry. At both times, acetylcholinesterase positive processes were densely distributed in the grafts of estradiol valerate treated rats, while in rats without estradiol valerate treatment acetylcholinesterase positive reaction was essentially localized only on the cell bodies. These findings were more obvious at 2 weeks after transplantation than at 4 weeks. These results suggest that estrogen acts on cholinergic neurons as a growth factor.

Acetylcholinesterase↗
PubMed1992

Microinjection of smg/rap1/Krev-1 p21 into Swiss 3T3 cells induces DNA synthesis and morphological changes.

Microinjection of either Ki-rasVal-12 p21 or the GDP-bound form of Ki-ras p21 plus smg GDP dissociation stimulator (GDS), a stimulatory GDP/GTP exchange protein for Ki-ras p21, smg/rap1/Krev-1 p21, and rho p21, into quiescent Swiss 3T3 cells induced DNA synthesis irrespective of the presence or absence of insulin. The guanosine 5'-(3-O-thio)triphosphate (GTP gamma S)-bound form of smg p21B or the GDP-bound form of smg p21B plus smg GDS also induced DNA synthesis but only in the presence of insulin. Either the GDP-bound form of Ki-ras p21 or the same form of smg p21B alone was inactive, but smg GDS alone was slightly active only in the presence of insulin. The morphology of the cells was analyzed by scanning electron, phase-contrast, and confocal laser scanning microscopies. Ki-rasVal-12 p21 induced membrane ruffling irrespective of the presence or absence of insulin. The GTP gamma S-bound form of smg p21B showed the same effect only in the presence of insulin. Either the GDP-bound form of Ki-ras p21, the same form of smg p21B, or smg GDS alone was inactive. Upon microinjection of Ki-rasVal-12 p21, stress fibers markedly decreased and the cells became round and piled up. In contrast, upon microinjection of the GTP gamma S-bound form of smg p21B, stress fibers did not markedly decrease and the cells neither became round nor piled up. These results indicate that both ras p21 and smg p21 are mitogenic in Swiss 3T3 cells but that their actions are slightly different.

3T3 Cells↗
PubMed1992

Distribution of oxytocin and vasopressin neurons in the diencephalon of the Japanese horseshoe bat, Rhinolophus ferrumequinum. An immunohistochemical study.

The distribution of oxytocin (OXT) and vasopressin (VP) neurons in the diencephalon of the hibernating Japanese horseshoe bat, Rhinolophus ferrumequinum, was immunohistochemically investigated by the avidin-biotin complex method. Magnocellular OXT and VP neurons were localized mainly in the paraventricular nucleus and the supraoptic nucleus. In addition to these main nuclei, both kinds of magnocellular neurons were also found in the periventricular nucleus, perifornical area and lateral hypothalamic area. Extensively distributed parvocellular neurons containing only VP were observed in the rostral and middle portions of the suprachiasmatic nucleus. The size of OXT and VP magnocellular neurons was almost equal in the paraventricular and ventromedial supraoptic nuclei, whereas VP neurons were significantly larger than OXT neurons in the dorsolateral supraoptic nucleus. The OXT and VP cells in the ventral supraoptic nucleus showed a distinctive elliptical shape. Both OXT and VP fibers were distributed in the lateral habenular nucleus, stria medullaris thalami, lateral preoptic area, stria terminalis, and medial and supracapsular part of the bed nucleus of the stria terminalis. Moreover, OXT fibers were found in the substantia nigra, and VP fibers were noted in the nucleus reunions and the paraventricular nucleus of the thalamus.

Animals↗
PubMed1992

Bioavailability study of commercial sustained-release preparations of diclofenac sodium in gastrointestinal physiology regulated-dogs.

The gastrointestinal (GI) physiology of beagle dogs was regulated with a combined-treatment of intramuscular pentagastrin (10 micrograms/kg x 2) and intravenous atropine sulfate (0.02 mg/kg x 1). Here, the gastric acidity, the gastric emptying time and the small intestinal transit time in the regulated-dogs were respectively around pH 2, 0.7h and 4h, approximating those in healthy humans. The superiority of the regulated-dogs over the intact dogs was confirmed in comparative bioavailability studies by using two classes of commercial preparations. Both the conventional tablet and the sustained-release capsule of diclofenac sodium exhibited simple and similar average plasma concentration-time curves of free diclofenac in the intact dogs, while the latter preparation is reported to reveal a bimodal plasma curve of the drug in healthy humans. The regulated-dogs, however, permitted a bimodal average plasma pattern of the drug for the capsules due to an approximation of the GI physiology between humans and these classes of the dogs. The combined-treatment of beagle dogs with pentagastrin and atropine sulfate seems to supply a useful animal model in predicting the absorption characteristics of the sustained-release preparations and poor water-soluble drugs.

Animals↗
PubMed1992

Influence of spinal cord hemisection on the configurational changes in motor and primary afferent neurons and the chemical messenger alterations in the rat lumbar segments.

Cholera toxin B subunit (CTB), a retrograde transport marker, was injected into the rat gastrocnemius muscles, and changes in CTB-labeling pattern of motoneurons and primary afferent neurons at the level L4 and L5 after spinal cord hemisection of the L1 level were observed in conjunction with the alterations of chemical messengers such as serotonin (5-HT), calcitonin gene-related peptide (CGRP), substance P (SP), galanin (Gal), Met-enkephalin (Enk), and neuropeptide Y (NPY). Motoneurons at the L4 and L5 levels on the lesioned side exhibited significant shrinkage of their dendritic arbors without apparent loss of their number throughout all stages from 1 to 12 weeks after the hemisection of the spinal cord. Postoperatively, central processes of neuron of the dorsal root ganglia (DRG) on the lesioned side increased progressively compared to that on the contralateral side with the passage of time. The percentage of CTB-labeled neurons in the DRG has been consistently smaller in number on the lesioned side after the operation, and the difference between sides became more apparent during the later postoperative stages. 5-HT-containing fibers in the anterior and posterior horns on the lesioned side showed a significant decrease in the number, while no apparent changes were observed in the distribution of nerve fibers containing CGRP, SP, Gal, Enk, and NPY.

Afferent Pathways↗