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Biomedical subjects

M Imanishi

Publications and source records attributed to M Imanishi.

At least 19 recordsLinked to original sources
PubMed2006

Decrease in tetrahydrobiopterin as a possible cause of nephropathy in type II diabetic rats.

A decrease in renal synthesis of nitric oxide (NO) in the progression of diabetic nephropathy has been documented. As (6R)-5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor of NO synthase, we investigated whether BH4 deficiency is involved in the pathogenesis of nephropathy. Ten-week-old Otsuka Long-Evans Tokushima Fatty (OLETF) rats were used as a type II diabetic model, and Long-Evans Tokushima Otsuka (LETO) rats as the healthy controls. OLETF rats were orally treated with BH4 (10 mg/kg daily) or with water from 10 to 61 weeks of age. In another experiment, OLETF rats were treated orally with a calcium channel blocker, benidipine (5 mg/kg daily), or with 0.3% carboxymethyl cellulose (nontreated) from 10 to 52 weeks of age. Proteinuria was observed periodically, and at the end of the study, BH4 level and GTP cyclohydrolase I (GTPCH) activity in the kidney were measured. Proteinuria was observed at 13 weeks of age in the OLETF rats, and deteriorated until 61 weeks of age. Supplemental BH4 reduced the proteinuria. At 52 weeks of age, GTPCH activity and the BH4 level were decreased in the plasma and kidneys of OLETF rats, whereas they were significantly higher in the benidipine group than in the nontreated group. Proteinuria was milder in the benidipine group than in the nontreated group, without a concomitant decrease in blood pressure. Histologically observed glomerulosclerosis was mild in the BH4 and benidipine groups. In type II diabetic rats, renal BH4 is considered to play a crucial role in the pathogenesis of diabetic nephropathy. Benidipine was found to preserve BH4 levels, suggesting therapeutic renoprotective effects.

Animals↗
PubMed2005

Single nucleotide polymorphisms in the gene encoding Krüppel-like factor 7 are associated with type 2 diabetes.

AIMS/HYPOTHESIS: Although genetic susceptibility plays an important role in the pathogenesis of type 2 diabetes, most of the genes that influence susceptibility to type 2 diabetes have yet to be identified. Krüppel-like transcription factors are known to play important roles in development and cell differentiation, and have recently been implicated in the pathogenesis of type 2 diabetes. The present study aimed to examine the associations of single nucleotide polymorphisms (SNPs) in genes encoding members of the Krüppel-like-factor (KLF) family with type 2 diabetes in a large cohort of Japanese subjects. METHODS: We genotyped 33 SNP loci found in 12 KLF genes in subjects with type 2 diabetes and in subjects from the general population using the PCR-Invader assay. We also examined the effects of the overexpression of KLF7 on adipogenesis in 3T3-L1 cells. RESULTS: We identified a significant association between an SNP in KLF7 and type 2 diabetes (A vs C: p=0.004 after Bonferroni's correction, odds ratio=1.59, 95% CI 1.27-2.00). The expression of Klf7 decreased in response to the differentiation of 3T3-L1 adipocytes, and the overexpression of KLF7 resulted in significant inhibition of adipogenesis in 3T3-L1 cells. CONCLUSIONS/INTERPRETATION: These results indicate that the gene encoding KLF7 is a novel candidate for conferring genetic susceptibility to type 2 diabetes.

3T3 Cells↗
PubMed2005

A case of acquired smooth muscle hamartoma of the scrotum.

We report a case of acquired smooth muscle hamartoma (ASMH) of tunica dartos, believed to be only the fifth so far reported. A 24-year-old man had a 6-month history of an asymptomatic tight and thickened scrotum. The skin was difficult to pinch. A biopsy specimen from the skin showed increased and proliferated smooth-muscle bundles composed of well-differentiated and uniform spindle cells that showed typical features of acquired smooth muscle hamartoma. Interestingly, dilatations of the lymph vessels were noted in the upper dermis above the proliferated smooth muscles. It has been reported recently that long-standing severe lymphoedema may cause histological features mimicking ASMH. As the present case was not preceded by oedema of the scrotum, we consider this case to be true ASMH.

Adult↗
PubMed2005

Down-regulation of metabotropic glutamate receptor 1alpha in globus pallidus and substantia nigra of parkinsonian monkeys.

Enhanced glutamatergic neurotransmission via the subthalamopallidal or subthalamonigral projection seems crucial for developing parkinsonian motor signs. In the present study, the possible changes in the expression of metabotropic glutamate receptors (mGluRs) were examined in the basal ganglia of a primate model for Parkinson's disease. When the patterns of immunohistochemical localization of mGluRs in monkeys administered systemically with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were analysed in comparison with normal controls, we found that expression of mGluR1alpha, but not of other subtypes, was significantly reduced in the internal and external segments of the globus pallidus and the substantia nigra pars reticulata. To elucidate the functional role of mGluR1 in the control of pallidal neuron activity, extracellular unit recordings combined with intrapallidal microinjections of mGluR1-related agents were then performed in normal and parkinsonian monkeys. In normal awake conditions, the spontaneous firing rates of neurons in the pallidal complex were increased by DHPG, a selective agonist of group I mGluRs, whereas they were decreased by AIDA, a selective antagonist of group I mGluRs, or LY367385, a selective antagonist of mGluR1. These electrophysiological data strongly indicate that the excitatory mechanism of pallidal neurons by glutamate is mediated at least partly through mGluR1. The effects of the mGluR1-related agents on neuronal firing in the internal pallidal segment became rather obscure after MPTP treatment. Our results suggest that the specific down-regulation of pallidal and nigral mGluR1alpha in the parkinsonian state may exert a compensatory action to reverse the overactivity of the subthalamic nucleus-derived glutamatergic input that is generated in the disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2001

Multiconnection of identical zinc finger: implication for DNA binding affinity and unit modulation of the three zinc finger domain.

Cys(2)-His(2)-type zinc finger proteins have a tandemly repeated array structure consisting of independent finger modules. They are expected to elevate the DNA binding affinity and specificity by increasing the number of finger modules. To investigate the relation between the number and the DNA binding affinity of the zinc finger, we have designed the two- to four-finger peptides by connecting the central zinc finger (finger 2) of Sp1 with the canonical linker sequence, Thr-Gly-Glu-Lys-Pro. Gel mobility shift assays reveal that the cognate three- and four-finger peptides, Sp1(zf222) and Sp1(zf2222), strongly bind to the predicted target sequences, but the two-finger peptide, Sp1(zf22), does not. Of special interest is the fact that the dissociation constant for Sp1(zf2222) binding to the target DNA is comparable to that for Sp1(zf222). The methylation interference, DNase I and hydroxyl radical footprintings, and circular permutation analyses demonstrate that Sp1(zf2222) binds to its target site with three successive zinc fingers and the binding of the fourth zinc finger is inhibited by DNA bending induced by the binding of the three-finger domain. The present results strongly indicate that the zinc finger protein binds to DNA by the three-finger domain as one binding unit. In addition, this information provides the basis for the design of a novel multifinger protein with high affinity and specificity for long DNA sequences, such as chromosomal DNAs.

Base Sequence↗
PubMed2001

Design of novel zinc finger proteins: towards artificial control of specific gene expression.

In this review, we summarize design strategies for generating proteins with desired sequences such as long contiguous base pairs and diverse sequence specificities based on the nature of Cys(2)-His(2) zinc finger proteins. Recent progress towards artificial DNA binding proteins has been achieved by structure-based design processes and by selection strategies. Indeed, a multi-zinc finger protein with an 18 (or 27)-base pair address, and new zinc finger proteins for diverse DNA target sites (TATA-box and p53 binding site) have been created successfully. Such novel zinc finger proteins will probably be useful tools in molecular biology and potentially in human medicine.

Animals↗
PubMed2001

Organization of inputs from cingulate motor areas to basal ganglia in macaque monkey.

The cingulate motor areas reside within regions lining the cingulate sulcus and are divided into rostral and caudal parts. Recent studies suggest that the rostral and caudal cingulate motor areas participate in distinct aspects of motor function: the former plays a role in higher-order cognitive control of movements, whereas the latter is more directly involved in their execution. Here, we investigated the organization of cingulate motor areas inputs to the basal ganglia in the macaque monkey. Identified forelimb representations of the rostral and caudal cingulate motor areas were injected with different anterograde tracers and the distribution patterns of labelled terminals were analysed in the striatum and the subthalamic nucleus. Corticostriatal inputs from the rostral and caudal cingulate motor areas were located within the rostral striatum, with the highest density in the striatal cell bridges and the ventrolateral portions of the putamen, respectively. There was no substantial overlap between these input zones. Similarly, a certain segregation of input zones from the rostral and caudal cingulate motor areas occurred along the mediolateral axis of the subthalamic nucleus. It has also been revealed that corticostriatal and corticosubthalamic input zones from the rostral cingulate motor area considerably overlapped those from the presupplementary motor area, while the input zones from the caudal cingulate motor area displayed a large overlap with those from the primary motor cortex. The present results indicate that a parallel design underlies motor information processing in the cortico-basal ganglia loop derived from the rostral and caudal cingulate motor areas.

Action Potentials↗
PubMed2001

Immunohistochemical localization of voltage-gated calcium channels in substantia nigra dopamine neurons.

The rhythmic firing of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc) is thought to be mediated by nifedipine-sensitive Ca(2+) channels, although an involvement of omega-conotoxin-sensitive Ca(2+) channels is also suggested. In an attempt to localize such Ca(2+) channels at both the regional and cellular levels, their expression and distribution patterns were immunohistochemically investigated in the rat SNc. The three distinct subtypes of voltage-gated Ca(2+) channels were tested: the class B N-type alpha 1 subunit (CNB1), the class C L-type alpha 1 subunit (CNC1) and the class D L-type alpha 1 subunit (CND1). A large number of SNc neurons showed intense immunoreactivity against CND1 and they were distributed throughout the entire extent. By contrast, many fewer neurons displayed less intense CNC1 immunoreactivity and many of them were located in the lateral aspect of the SNc. No immunoreactivity against CNB1 was detected in the SNc. Moreover, double immunofluorescence analysis in combination with tyrosine hydroxylase staining revealed that virtually all DA neurons were CND1-immunoreactive whereas many DA neurons especially in the medial SNc exhibited only faint or no immunoreactivity against CNC1. Both CNC1 and CND1 were expressed in cell bodies and proximal dendrites of SNc DA neurons, whilst their distal dendrites that penetrated into the substantia nigra pars reticulata expressed CND1 alone. Thus, the ubiquitously and intensely expressed class D alpha 1 subunit of L-type Ca(2+) channels that is sensitive to both nifedipine and omega-conotoxin may be responsible for the pacemaker activity of SNc DA neurons.

Action Potentials↗
PubMed2001

Inhibitory effect of baicalein, a flavonoid in Scutellaria Root, on eotaxin production by human dermal fibroblasts.

Eotaxin is an eosinophil-specific chemokine associated with the recruitment of eosinophils to sites of allergic inflammation. "Saiboku-to" (Formula magnoliae et bupleuri) is a kampo herbal medicine used for the treatment of bronchial asthma in Japan. In this study, we investigated the effects of Scutellaria Root, a major herb in Saiboku-to and its components such as baicalein and baicalin on eotaxin production by IL-4 plus TNF-alpha-stimulated human fibroblasts. An extract of Scutellaria Root markedly inhibited eotaxin production. Four major flavonoids from Scutellaria Root were found to show inhibitory activity on eotaxin production at a concentration of 10 micrograms/ml in the order of baicalein > oroxylin A > baicalin > skullcapflavon II. The inhibitory effect of baicalein was expressed in a dose-dependent manner, and almost 50% inhibition was observed at 1.8 micrograms/ml. Furthermore, baicalein prevented human eotaxin mRNA expression in IL-4 plus TNF-alpha-stimulated human fibroblasts. These results help explain the pharmacological efficacy of Scutellaria Root in the treatment of bronchial asthma since it would suppress eotaxin associated recruitment of eosinophils.

Asthma↗
PubMed2001

Prostaglandin I(2)/E(2) ratios in unilateral renovascular hypertension of different severities.

Differences between prostaglandins I(2) and E(2) in their renal synthesis and pathophysiological roles were investigated in unilateral renovascular hypertension of different severities in 18 patients: 6 with mild stenosis (<75% of the diameter) of the renal artery, 7 with moderate stenosis (75% to 90%), and 5 with severe stenosis (>90%). Before and after aspirin administration (10 mg/kg), renal venous and aortic plasma was assayed for 6-ketoprostaglandin F(1alpha) (instead of prostaglandin I(2)), prostaglandin E(2), and renin activity. In mild or moderate stenosis, the mean 6-ketoprostaglandin F(1alpha) level in renal venous plasma from the stenotic side was not different from that from the normal side or from aortic plasma. Prostaglandin E(2) levels and renin activity in such patients were higher on the stenotic side than on the normal side and higher in venous than in aortic plasma. Aspirin inhibited prostaglandin E(2) synthesis and suppressed renin release from stenotic kidneys and lowered blood pressure as the renin activity decreased in patients with mild or moderate stenosis. In severe stenosis, levels of 6-ketoprostaglandin F(1alpha) and prostaglandin E(2) were higher on the stenotic side than on the normal side and higher in venous than in aortic plasma. Aspirin inhibited the synthesis of both prostaglandins and suppressed renin release from the stenotic kidney. In patients with unilateral renovascular hypertension with mild or moderate stenosis of the renal artery, prostaglandin E(2), rather than I(2), seems to contribute to further acceleration of renin release. Prostaglandin I(2) may increase and participate in further renin release when the stenosis is severe.

Adolescent↗
PubMed2001

Sodium sensitivity of blood pressure appearing before hypertension and related to histological damage in immunoglobulin a nephropathy.

Patients with renal parenchymal disease exhibit sodium-sensitive hypertension. We examined patients with immunoglobulin A (IgA) nephropathy to determine whether this sensitivity appears before hypertension begins and whether this sensitivity is related to histological damage. Thirty-eight patients with IgA nephropathy followed a diet with an ordinary sodium level for 1 week and a sodium-restricted diet for 1 week, in random order, and were divided into 3 groups by their systemic blood pressure on the diet with an ordinary sodium level (optimal, <120/<80 mm Hg, n=15; normal to high-normal, 120 to 139/80 to 89 mm Hg, n=18; hypertensive, >/=140/>/=90 mm Hg, n=5). The sodium sensitivity index was calculated as the reciprocal of the slope of the pressure-natriuresis curve drawn by linkage of 2 datum points obtained during the different diets. The scores for glomerulosclerosis and tubulointerstitial damage were evaluated semiquantitatively. The sensitivity index, glomerulosclerosis score, and score for tubulointerstitial damage were higher in patients with normal to high-normal blood pressure or hypertension than in patients with optimal pressure. The sensitivity index was significantly correlated with glomerulosclerosis (P=0.001) and tubulointerstitial damage (P=0.002). In patients with normal to high-normal pressure, sodium restriction lowered blood pressure to the optimal range and decreased proteinuria. In patients with IgA nephropathy, sodium sensitivity of blood pressure related to renal histological damage appears before hypertension.

Adult↗
PubMed2001

Sodium sensitivity related to albuminuria appearing before hypertension in type 2 diabetic patients.

OBJECTIVE: To find whether sodium sensitivity of blood pressure appears before hypertension and whether the sensitivity is related to diabetic nephropathy, we examined type 2 diabetic patients with normal levels of serum creatinine. RESEARCH DESIGN AND METHODS: A total of 32 patients were divided into three age-matched groups: 11 patients had normoalbuminuria, 12 had microalbuminuria, and 9 had macroalbuminuria. Patients stayed on a diet with ordinary sodium levels for 1 week and a sodium-restricted diet for 1 week, in random order. Urinary excretion of sodium and albumin and systemic blood pressure were measured daily. A pressure-natriuresis curve was drawn by linkage of the two datum points obtained in the steady state during the different diets. We calculated the sodium sensitivity index as the reciprocal of the slope of this curve. RESULTS: The median sodium sensitivity index and the mean blood pressure were higher in micro- and macroalbuminuric patients than in normoalbuminuric patients. Eighteen patients were without hypertension (<140/90 mmHg); of these, 10 had blood pressure readings <130/85 mmHg with ordinary sodium levels. Urinary albumin was correlated with the index but not with blood pressure. For these 10 patients, the index in those with albuminuria was higher than in those with normoalbuminuria. In such patients with albuminuria, sodium restriction decreased albuminuria and blood pressure. CONCLUSIONS: In type 2 diabetic patients with albuminuria but normal levels of serum creatinine, sodium sensitivity of blood pressure appears before hypertension and is related to albuminuria; sodium restriction is one treatment for diabetic nephropath, even without hypertension.

Adult↗
PubMed2000

Inducible expression of a Th2-type CC chemokine thymus- and activation-regulated chemokine by human bronchial epithelial cells.

CCR4 is now known to be selectively expressed in Th2 cells. Since the bronchial epithelium is recognized as an important source of mediators fundamental to the manifestation of respiratory allergic inflammation, we studied the expression of two functional ligands for CCR4, i.e., macrophage-derived chemokine (MDC) and thymus- and activation-regulated chemokine (TARC), in bronchial epithelial cells. The bronchial epithelium of asthmatics and normal subjects expressed TARC protein, and the asthmatics showed more intense expression than the normal subjects. On the other hand, MDC expression was only weakly detected in the asthmatics, but the intensity was not significantly different from that of normal subjects. Combination of TNF-alpha and IL-4 induced expression of TARC protein and mRNA in bronchial epithelial A549 cells, which was slightly up-regulated by IFN-gamma. The enhancement by IFN-gamma was more pronounced in bronchial epithelial BEAS-2B cells, and a maximum production occurred with combination of TNF-alpha, IL-4, and IFN-gamma. On the other hand, MDC was essentially not expressed in any of the cultures. Furthermore, expressions of TARC protein and mRNA were almost completely inhibited by glucocorticoids. These results indicate that the airway epithelium represents an important source of TARC, which potentially plays a role via a paracrine mechanism in the development of allergic respiratory diseases. Furthermore, the beneficial effect of inhaled glucocorticoids on asthma may be at least in part due to their direct inhibitory effect on TARC generation by the bronchial epithelium.

Adult↗
PubMed2000

DNA-bending finger: artificial design of 6-zinc finger peptides with polyglycine linker and induction of DNA bending.

DNA structural changes such as bending play an important role in various biological reactions. Not only protein binding to its specific DNA sequence but also DNA bending induced by the protein is indispensable for unique gene expression. Therefore, an artificial protein that induces a DNA conformational change is interesting as a transcriptional regulator of a specific gene. We created 6-zinc finger proteins, Sp1ZF6(Gly)n (n = 4, 7, 10), by connecting two DNA binding domains of transcription factor Sp1 with flexible polyglycine peptide linkers, and their effects on DNA structure were compared with that of native 3-zinc finger Sp1(530-623). Gel electrophoretic methods revealed that Sp1ZF6(Gly)7 and Sp1ZF6(Gly)10 bind to two distal GC boxes and result in DNA bending. Evidently, the hydroxyl radical footprinting analysis demonstrated that hypersensitive cleavage was observed at the 5'-TA step in the intervening region bound by Sp1ZF6(Gly)7 or Sp1ZF6(Gly)10. The phasing assays strongly suggested that the induced DNA bending was directed toward the major groove and that Sp1ZF6(Gly)7 caused the most drastic directional change in DNA bending. Of special interest are the facts that the newly designed 6-finger peptides Sp1ZF6(Gly)7 and Sp1ZF6(Gly)10 can induce DNA bending at the intervening region of the two distal binding sites and that the linker length between two 3-zinc finger motifs has a crucial effect on the entire DNA-bending direction. Such DNA-bending fingers may be feasible for use as a gene expression regulator based on the structural change in DNA in the future.

Amino Acid Sequence↗
PubMed2000

A cortical motor region that represents the cutaneous back muscles in the macaque monkey.

A cortical motor region that represented the cutaneous muscles on the back was identified on the medial wall of the frontal lobe in the macaque monkey. In this region, neurons responded to somatosensory stimuli such as light touch or squeezing of the back skin, and intracortical microstimulation elicited contraction of the back skin. Such a region was located primarily on the dorsal bank of the cingulate sulcus, corresponding to the dorsal cingulate motor area.

Animals↗
PubMed2000

Preliminary evaluation of [1-11C]octanoate as a PET tracer for studying cerebral ischemia: a PET study in rat and canine models of focal cerebral ischemia.

Octanoate is taken up into the brain and is converted in astrocytes to glutamine through the TCA cycle after beta-oxidation. We speculate that [1-11C]octanoate may be used as a tracer for astroglial functions and/or fatty acid metabolism in the brain and may be useful for studying cerebral ischemia. In the present study we investigated brain distribution of [1-11C]octanoate and compared it with cerebral blood flow (CBF) by using rat and canine models of middle cerebral artery (MCA) occlusion and a high resolution PET. In rats brain distribution of [15O]H2O measured 1-2 h and 5-6 h after insult was compared with that of [1-11C]octanoate measured 3-4 h after insult. Radioactivity ratios of lesioned to normal hemispheres determined with [15O]H2O were lower than those determined with [1-11C]octanoate. These results were confirmed by a study on a canine model of MCA-occlusion. Twenty-four hours after insult, CBF decreased in the MCA-territory of the occluded hemisphere, whereas normal or higher accumulation of [1-11C]octanoate was observed in the ischemic regions. The uptake of [1-11C]octanoate-derived radioactivity therefore increased relative to CBF in the ischemic regions, indicating that [1-11C]octanoate provides functional information different from CBF. In conclusion, we found that [1-11C]octanoate is a potential radiopharmaceutical for studying the pathophysiology of cerebral ischemia.

Animals↗