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Biomedical subjects

H Ishiguro

Publications and source records attributed to H Ishiguro.

At least 163 records · Page 9Linked to original sources

Presence of eight distinct homeobox-containing genes in cnidarians.

Using the polymerase chain reaction, we identified four different homeobox-containing genes in Hydra magnipapillata. Three of them, cnox1-Hm, cnox2-Hm and cnox4-Hm, were equivalent to homeobox genes that had already been identified in other species of cnidarians. cnox5-Hm was a new homeobox gene and was very similar to Mox1 in the mouse. Together with the published data, our results indicate that there are at least eight distinct classes of homeobox genes in cnidarians. These homeobox genes show a maximum of 60 to 77% identity in terms of the amino acid residues in their homeodomains to certain classes of homeobox genes that have been identified in Drosophila.

Amino Acid Sequence↗

Neuron-specific expression of the human dopamine beta-hydroxylase gene requires both the cAMP-response element and a silencer region.

Dopamine beta-hydroxylase (DBH), the enzyme catalyzing the conversion of dopamine to norepinephrine, is specifically expressed in adrenergic and noradrenergic neurons in the central nervous system. DNase I hypersensitive sites were found in the 5'-flanking region of the DBH gene in noradrenergic human neuroblastoma SK-N-BE(2)C cells, but not in DBH-nonexpressing HeLa cells. We report here that the 4.3-kilobase upstream sequence of the human DBH gene confers cell type-specific expression as assessed by transient expression assay. Furthermore, deletional and mutational analyses revealed two genetic regulatory elements required for the regulation of cell type specificity. First, deletion of the cAMP-response element (CRE) abolished > 95% of the transcriptional activity by the DBH upstream promoter, thus implicating the CRE as an essential positive genetic element. Second, deletion of a region between -490 and -263 base pairs resulted in 10-fold increase of reporter gene activity only in HeLa cells, indicating that this region contains a cell-specific silencer. A 13-base pair fragment residing within that region shows 77% sequence identity with the neuron-specific silencer motif recently identified in two neuronal genes, i.e. SCG10 and type II sodium channel genes. We propose that the interplay between the CRE and this neuron-specific silencer region plays an important role in the tissue-specific expression of the DBH gene in noradrenergic cells.

Animals↗

Longitudinal changes of plasma pancreatic enzymes and hormones in experimental pancreatolithiasis in dogs.

Plasma pancreatic enzymes and hormones were longitudinally observed after producing partial obstruction of the major pancreatic duct in dogs to study an initial state of chronic pancreatitis or pancreatolithiasis. Fasting plasma immunoreactive cationic trypsin was elevated during the first six months and then decreased in a subgroup with pancreatic calculi, marked fibrosis, or duct dilatation when compared with the corresponding opposite at the end of the 12-month period. Similar but less prominent changes were found in fasting plasma immunoreactive pancreatic polypeptide (IRPP). Plasma amylase, glucose, or immunoreactive insulin or glucagon (IRG) show no significant variation. Plasma IRG and IRPP responses to intravenous insulin were reduced in the subgroups with marked pancreatic changes towards the end of the 12-month period. These results suggest that plasma pancreatic enzymes and hormones remain elevated as long as pancreatic damage is mild and then start to decline as the damage progresses in chronic pancreatitis or pancreatolithiasis.

Amylases↗

Expression of the large myelin-associated glycoprotein isoform in rat oligodendrocytes around cerebral infarcts.

An immunohistochemical method that uses two specific antisera-distinguishable myelin-associated glycoprotein (MAG) isoforms showed an expression of large MAG isoform (L-MAG) protein in the oligodendrocyte cytoplasms in the white matter around experimental cerebral infarcts produced by occlusion of the left middle cerebral artery in the rat. L-MAG protein also was detected in the white matter on the contralateral side. This protein appears prior to S-MAG protein in myelination and remyelination in the central and peripheral nervous systems, and is believed to function in myelin formation. Because L-MAG protein has been found in the oligodendrocyte cytoplasm only in the early development period, its appearance in this cytoplasm after ischemic insult is evidence of MAG regeneration.

Animals↗

Expression of myelin-associated glycoprotein isoforms after sciatic nerve crush injury in mice.

The large myelin-associated glycoprotein isoform (L-MAG) protein and small myelin-associated glycoprotein isoform (S-MAG) protein were demonstrated after sciatic nerve crush injury in mice by an immunoblotting technique using specific antibodies to the L-MAG protein and the S-MAG protein, respectively. Immunoblots indicated a rapid decrease in expression of both isoform proteins in the crushed sciatic nerves to < 10% of the control side. By 13 d after injury, L-MAG protein expression had quickly recovered to 100% of the control level. Following the increase in L-MAG protein expression, S-MAG protein expression recovered to 100% by 20 d after injury. It has been reported that the developmental maximum expression of L-MAG protein precedes that of S-MAG protein in both central and peripheral nervous system (CNS and PNS). Our previous work demonstrated that L-MAG mRNA was characteristically induced at the time of most active myelination, including remyelination in the CNS. We here have shown the expression of L-MAG protein precedes that of S-MAG protein during active remyelination in the PNS. This suggests that it plays an important role in the early stage of myelin formation.

Animals↗

Comparison of nucleotide sequences from upstream of the DQ52 gene to the S mu region of immunoglobulin heavy-chain gene loci between Suncus murinus, mouse and human.

The nucleotide sequence of a 4621 base pair fragment of DNA, from a position upstream of DSQ52 to the S mu region within immunoglobulin heavy-chain gene loci of Suncus murinus was determined. The sequence contained one D gene, three JH genes and an enhancer. Suncus murinus is an insectivore and is one of the most primitive mammals. Both primates and rodents are thought to have originated from insectivores and to have evolved separately. We also determined the nucleotide sequence of a region between human JH genes and the enhancer which has not previously been reported. Thus, the sequences of the entire region from each of the three species, Suncus murinus, human and mouse are now available. Comparison of the nucleotide sequence of this region between these three species indicated that D and JH genes, consisting of coding and signal regions, are highly conserved. Moreover, although extensive sequence homology in the region between JH and S mu was observed between mouse and human, only core portions of the enhancer region of Suncus murinus exhibited homology to those of mouse and human. Sequence conservation of JH genes in Suncus murinus, mouse and human was observed not only at the amino-acid level, but also at the nucleotide level, including the third letters of the codons. It is suggested that JH genes may play a role in the metabolism of the DNA and/or RNA.

Algorithms↗

Effect of a new synthetic trypsin inhibitor on taurocholate-induced acute pancreatitis in rats.

The effect of a novel synthetic trypsin inhibitor, 4-sulfamoylphenyl 4-guanidinobenzoate methanesulfonate (ONO-3307), on severe acute pancreatitis was studied by changing its timing, frequency, and dose in trypsin-taurocholate-induced acute experimental pancreatitis in rats. Rats were divided into four groups according to difference of ONO-3307 administration: group A, 2 mg/0.5 ml of ONO-3307 s.c. 1 h before and after induction of pancreatitis; group B, 2 mg/0.5 ml s.c. 1 and 3 h after; group C, 4 mg/1 ml s.c. 1 h before; group D, 4 mg/1 ml s.c. 1 h after. The survival rate at 24 h was significantly improved in group A (75% in A vs. 17% in control; p < 0.01) and in group B (57 vs. 29%; p < 0.05), but not in group C or D. Amylase and immunoreactive trypsin in serum and ascites of the treated were significantly lower than those of controls in both groups A and B. The survival rates were improved dose dependently when ONO-3307 was administered 1 h before and after induction of pancreatitis. ONO-3307 showed favorable effects on the initial stage of severe acute pancreatitis when given in divided doses to maintain the effective serum levels.

Acute Disease↗

The effect of somatostatin analogue octreotide on amylase secretion from mouse pancreatic acini.

To clarify whether somatostatin has an inhibitory effect on pancreatic acinar cells, we studied the effect of a long-acting analogue of somatostatin, octreotide, on amylase secretion from isolated mouse pancreatic acini. Octreotide (100 nM) had no inhibitory effects on amylase secretion stimulated by secretin or vasoactive intestinal polypeptide (VIP), while reducing the increase of cyclic adenosine 3',5'-monophosphate (cAMP). On the other hand, octreotide inhibited synergistic amylase secretion induced by secretin or VIP in combination with cholecystokinin (CCK). Octreotide also reduced synergistic amylase secretion by secretin or VIP in combination with calcium ionophore A23187. CCK and A23187 did not alter the increase of cAMP induced by secretin and the inhibitory effect of octreotide on cAMP production. Octreotide did not significantly inhibit amylase secretion stimulated by dibutyryl cAMP (dbcAMP) alone, but reduced synergistic amylase secretion by dbcAMP+A23187. Results obtained above reveal that octreotide has a direct inhibitory effect on amylase secretion from mouse pancreatic acini and probably affects stimulus secretion coupling at a point distal to the production of cAMP, besides inhibiting adenylate cyclase.

Amylases↗

[Familial juvenile parkinsonism with dementia and autonomic failure--a case report].

A case of familial juvenile parkinsonism with dementia, orthostatic hypotension, neurogenic bladder and constipation was reported. He had been in a good health until the age of 28 when a finger tremor occurred on effort to hold hands in a definite position, and disturbances in gait and speech were noted. These symptoms were relieved by levodopa treatment followed by dyskinesia and motor fluctuations. Three years later, he complained of faintness, constipation and urinary frequency. The neurological examination revealed mentally sound male with masked face, tremor and rigidity in his extremities, and short step gait with lateropulsion. Urodynamic study showed uninhibited bladder. In the following years, orthostatic hypotension, dysuria and urinary retention developed gradually. He became mentally loose and was unable to take medicines appropriately. When in the Nishiojiya Byoin National Sanatorium, he tried to snake out the hospital many times. His parents and a brother suffered from Parkinson's disease and juvenile parkinsonism, respectively, suggesting an autosomal dominant inheritance. On admission to our hospital, he was apathetic. He had masked face, bilateral postural tremor, frozen gait and dyskinesia in the right lower extremity. Little bradykinesia or rigidity was noted. His muscle tone and deep tendon reflexes were decreased but neither muscular wasting, weakness, ataxia nor sensory disturbance was observed. Laboratory data including ceruloplasmin, copper, dopamine-beta-hydroxylase and lysosomal enzyme activities were normal except for mild anemia. A cranial CT scan revealed mild cortical atrophy in the frontal and temporal lobes, but nerve conduction study and cortical evoked potentials showed no abnormality. While in the hospital, his mental functions deteriorated to the state of dementia and orthostatic hypotension became apparent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Isolation of a hagfish gene that encodes a complement component.

It has been widely accepted that cyclostomes are the most primitive vertebrates extant with the ability to produce antibodies. We isolated cDNA clones that encode a putative 'antibody' from one of the cyclostomes, Eptatretus burgeri. The amino acid sequence predicted from the nucleotide sequences of the cDNA clones indicated that this gene does actually encode the proteins isolated as hagfish 'antibodies' by various investigators. However, these proteins are not similar to mammalian immunoglobulins but have some characteristics common to complements C3, C4 and C5 in higher vertebrates. We discuss the relationships of the isolated gene for hagfish complement with the mammalian genes for complements C3, C4 and C5. We also discuss the possibility of the presence of antibodies in cyclostomes.

Amino Acid Sequence↗

Plasticity of the sympathetic nervous system innervating the cerebral arteries in rats.

In order to investigate the neuroplasticity of the peripheral sympathetic nervous system innervating the cerebral blood vessels, we observed and traced the sprouting nerve fibers originating in the contralateral superior cervical ganglion (SCG) into the previously denervated cerebral arteries following unilateral excision of the SCG and/or decentralization of the contralateral SCG in young rats (4 weeks old). These nerve fibers were labeled anterogradely with wheat germ agglutinin-horseradish peroxidase or stained immunohistochemically with anti-tyrosine hydroxylase antibody. Eight weeks after the right SCG excision, reinnervating nerve fibers originating in the contralateral ganglion formed a circular pattern of nerve plexus only on the wall of the main cerebral arteries of the circle of Willis in the ganglionectomized side. However, the decentralization of the contralateral SCG, which was performed simultaneously with a unilateral SCG excision, prevented the nerve sprouting into the denervated regions. Unilateral decentralization of SCG itself failed to affect their distribution pattern or their density of nerve fibers originating in the ganglion. It is concluded that in the young rat the outgrowth of the sympathetic nerve fibers into the denervated cerebral arteries was strongly impeded by the disconnection of ganglion cells from the central nervous system, while the decentralization alone could not affect the innervation pattern of the postganglionic fibers which have been already built-up in the cerebral arterial system.

Animals↗

Pancreatic stone predominantly composed of fatty acid calcium.

A 41-year-old man with chronic pancreatitis and pancreatic stones predominantly composed of fatty acid calcium is reported. He had complained of occasional abdominal pain for 10 years and visited the hospital because of a severe attack of abdominal pain. Laboratory data supported a diagnosis of pancreatitis. Computed tomography (CT) showed a high-density area in the head of the pancreas, and the CT number of this high-density area was lower than usual for pancreatic stones. Ultrasonography and endoscopic retrograde pancreatography showed a cystic lesion with small pancreatic stones in the head of the pancreas and irregular dilatation of the main pancreatic duct. Pancreaticojejunostomy and resection of pancreatic cyst were carried out for repeated episodes of abdominal pain under the diagnosis of chronic pancreatitis. The pancreatic stones obtained at surgery were proved to be mainly composed of fatty acid calcium after analysis of chemical composition of the stones. Fatty acid calcium was sometimes found in the biliary stones but never in the pancreatic stones.

Adult↗

Relationship between endothelin and thromboxane A2 in rat liver microcirculation.

In our previous study, we determined changes in hepatic blood flow using a Laser Doppler blood flow meter after i.v. injection of endothelin-1 (ET-1) or endothelin-3 (ET-3) at 2 nmol/kg in rats and found that ET-3 caused greater decreases in blood flow than ET-1. In the present study, we determined how the arachidonic acid cascade, mainly thromboxane A2 (TXA2), is related to ET-1 and ET-3 using indomethacin (INDO), which inhibits the biosynthesis of prostaglandin (PG), and OKY-046, a selective inhibitor of TXA2 synthesis. In the first series of experiments, ET-1 and ET-3 were administered after inhibiting the biosynthesis of PG by s.c. injection of 2 mg/kg of INDO. While INDO failed to inhibit the slight decrease in hepatic blood flow induced by ET-1, it significantly inhibited the marked decrease in hepatic blood flow elicited by ET-3. In the next series of experiments, ET-1 and ET-3 were administered after administration of 20 mg/kg of OKY-046. OKY-046 showed no effects in animals treated with ET-1, as in those pre-treated with INDO, while it significantly inhibited the decreases in hepatic blood flow induced by ET-3. These findings suggest that ET-1 decreases hepatic blood flow due to its direct effects although to a lesser extent than ET-3, while ET-3 does so due not only to its direct effects but also to TXA2-mediated effects. It is therefore likely that in addition to ET family peptides, PG-mediated mechanisms are involved in the regulation of hepatic microcirculation by ETs.

Animals↗

ET-3 sensitive reduction of tissue blood flow in rat liver.

Changes in gastric mucosal and hepatic tissue blood flow were simultaneously determined using a laser-Doppler blood flow meter in rats given i.v. injection of endothelin-1 (ET-1) and endothelin-3 (ET-3), both at 2 nmol/kg. Gastric mucosal blood flow decreased significantly after administration of ET-1 compared to after administration of ET-3. Decreases in blood flow due to ET-1 were reversed by pre-treatment with 10 mg/kg of BQ-123 (sodium salt), an ETA receptor antagonist, to levels comparable to those induced by ET-3, but BQ-123 had no effects on decreases in blood flow due to ET-3. On the other hand, decreases in hepatic tissue blood flow by ET-3 were significant compared to those by ET-1. Decreases in hepatic tissue blood flow due to ET-1 were slightly inhibited by pre-treatment with 10 mg/kg of BQ-123, but it had no effect at all on decreases due to ET-3. These findings indicate that decreases in gastric mucosal blood flow are mainly caused by ET-1 via ETA receptors inhibited by BQ-123, while decreases in hepatic tissue blood flow are caused mainly by ET-3 via non-ETA receptors not inhibited by BQ-123. The fact that ET-3 decreases blood flow more significantly than ET-1 suggests the involvement of ET-3 selective receptors (ETc). The findings obtained in the present study indicate that complex mechanisms are involved in the regulation of tissue blood flow by ET, with different receptor subtypes and ET family peptides being involved according to the type of tissue.

Animals↗

Carbohydrate binding specificity of monoclonal antibodies raised against lactose-protein Maillard adducts.

Three hybridoma antibodies (L101, L104, and L117) specific for lactose-protein amino carbonyl products (Maillard adducts) were obtained by immunizing mice with the lactose-ovalbumin Maillard adduct and by screening with the lactose-bovine serum albumin (BSA) adduct. They reacted with the Maillard adducts of lactose with several different proteins, but not with the adducts of several other reducing sugars. L101 reacted well with the lactose-BSA adducts formed by 2- to 16-day incubation, whereas L104 and L117 reacted with the advanced stage reaction products but not with the adducts of 2-day incubation. The competitive inhibition of the antibody binding by several mono- and disaccharides showed that lactulose (4-O-beta-D-galactopylanosyl-D-fructose) was the best inhibitor for all three antibodies, and that L104 and L117 were inhibited by methyl-beta-D-galactoside more effectively than L101. These results suggested that different components produced during the progress of the Maillard reaction could be antigenic determinants, and that the carbohydrate moiety including the terminal galactosyl residue played an important role in the antibody binding to the lactose-protein Maillard adducts.

Animals↗

Effect of pravastatin, a potent 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, on survival of AH130 hepatoma-bearing rats.

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor is known to have an inhibitory effect on cell growth in addition to a cholesterol-lowering effect. This study examined the effect of pravastatin, a potent inhibitor of HMG-CoA reductase, on the survival of AH130 hepatoma-bearing rats. Pravastatin (1, 2, or 8 mg/kg body weight) was intraperitoneally injected once a day into tumor-bearing rats. The difference in the survival curves was significant between the controls and the rats treated with 8 mg/kg of pravastatin (P < 0.019 by logrank test) but not between the controls and the rats treated with 1 or 2 mg/kg of the inhibitor. The tumor volume was significantly decreased in the rats treated with 8 mg/kg of pravastatin (P < 0.05). These observations showed that intraperitoneal injection of pravastatin could improve the survival of AH130 hepatoma-bearing rats and had an inhibitory effect on the growth of the ascites form tumor.

Animals↗

Effects of calmodulin inhibitors on amylase secretion from rat pancreatic acini.

To investigate the role of calmodulin in stimulus-secretion coupling in pancreatic acinar cells, we studied the effects of W-7, a calmodulin inhibitor, and KN-62, a specific inhibitor of Ca2+/calmodulin-dependent protein kinase II (Ca2+/CaM kinase II), on amylase secretion from rat pancreatic acini. Calmodulin inhibitor (W-7, 100 microM) and Ca2+/CaM kinase II inhibitor (KN-62, 10 microM) reduced amylase secretion stimulated by cholecystokinin (CCK) or carbachol. W-7 and KN-62 also inhibited amylase secretion stimulated by both calcium ionophore (A23187) and phorbol ester (12-O-tetradecanoylphorbol-13-acetate, TPA). To clarify the role of calmodulin in the interaction of intracellular mediators, pancreatic acini were permeabilized with streptolysin O. Following permeabilization, amylase secretion was stimulated by submicromolar free Ca2+, and this Ca(2+)-dependent amylase secretion was enhanced by guanosine 5'-[gamma-thio]triphosphate (GTP gamma S), TPA or cyclic adenosine 3',5'-monophosphate (cAMP). W-7 and KN-62 had no effects on amylase secretion stimulated by Ca2+ alone, but inhibited the enhancement in Ca(2+)-dependent amylase secretion by GTP gamma S, TPA or cAMP. These data suggest that calmodulin plays an important role in Ca(2+)-dependent amylase secretion from pancreatic acinar cells and in the interaction between Ca2+ and other intracellular messengers.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

Immunohistochemical localization of myelin-associated glycoprotein isoforms during the development in the mouse brain.

The developmental changes in localization of myelin-associated glycoprotein (MAG) isoforms in the mouse brain were demonstrated by an immunohistochemical method using antisera specific to two MAG isoforms. The antiserum to the large isoform of MAG (L-MAG) stained the myelin sheaths and the cytoplasm of oligodendroglia in the active myelinating stage in the mouse central nervous system. However, the antiserum to the small isoform of MAG (S-MAG) stained only myelin sheaths in the adult stage. These findings suggest that L-MAG plays an important role in active myelination.

Animals↗