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Biomedical subjects

S Amano

Publications and source records attributed to S Amano.

At least 127 records · Page 7Linked to original sources
PubMed1998

In vivo comparison of PET and SPECT radiopharmaceuticals in detecting breast cancer.

UNLABELLED: Various radiopharmaceuticals for breast cancer detection have been used for scintimammography and PET. However, few comparative studies have described the uptake of radiopharmaceuticals as a method of detecting breast cancer. The aim of this study was to assess the radiopharmaceuticals for breast cancer imaging in experimental mice implanted with breast cancer cells. METHODS: Six radiopharmaceuticals were studied: three for PET [18F-fluorodeoxyglucose (FDG), L-18F-alpha-methyltyrosine (FMT) and 11C-methionine (C-Met)] and three for scintimammography [99mTc-tetrofosmin (TF), 99mTc-sestamibi (MIBI) and 201Tl-chloride (Tl)]. Biodistributions of six different tracers in mice implanted with MCF-7 breast cancer cells were studied 1 and 3 hr after injection. RESULTS: Tumor uptake 1 hr after injection was FMT = C-Met > FDG = TF > MIBI = Tl. Thallium-201-chloride showed the highest tumor-to-blood ratio (T/B) among all radiopharmaceuticals because of its fast clearance from circulation. The T/B of the six radionuclides used in this study ranged from 1.26 for C-Met to 12.83 for Tl. Tumor-to-muscle ratio (T/M) revealed FMT = C-Met > FDG > MIBI > TF = Tl. The T/M ranged from 0.20 for TF to 2.29 for FMT. Tumor-to-lung ratio (T/L) varied from 0.45 for TF to 2.41 for FMT. FMT revealed the highest T/L of all six radiopharmaceuticals. CONCLUSION: Among radiopharmaceuticals for PET, FMT seemed to be suitable in detecting MCF-7 tumor; whereas for scintimammography, MIBI, TF and Tl appeared to have almost the same detectability of MCF-7 tumor. The results of this study strongly suggest that FMT may have a potential in breast cancer imaging.

Animals↗
PubMed1997

Changes of immunoreactive neuropeptide Y, somatostatin and corticotropin-releasing factor (CRF) in the brain of a novel epileptic mutant rat, Ihara's genetically epileptic rat (IGER).

Ihara's genetically epileptic rat (IGER) is a rat mutant with genetically scheduled spontaneous convulsions mimicking human limbic seizures. In the present study, the possible changes of three neuropeptides, neuropeptide Y (NPY), somatostatin (SRIF) and corticotropin-releasing factor (CRF), in the brains of IGER were investigated. Increased contents of immunoreactive (IR) NPY were found only in the hippocampus of 2-month IGERs before developing convulsive seizures, while similar increases of IR-NPY were discovered in the striatum and pyriform and entorhinal cortex as well as hippocampus in 8-month IGERs with repetitive seizures. There were no significant differences in the brain contents of IR-SRIF and IR-CRF between IGERs and the controls at both ages. These findings indicate an enhanced rate of NPY synthesis in this experimental model of epilepsy which may play a critical role in the development of epileptogenesis.

Animals↗
PubMed1997

Functional role of endogenous CD14 in lipopolysaccharide-stimulated bone resorption.

Lipopolysaccharide (LPS) is a bacterial cell component that plays multifunctional roles in inflammatory reactions, and one of these roles is that of a powerful stimulator of bone resorption. However, the mechanism by which LPS stimulates bone resorption is not yet understood. In the present study, we show, by using mouse embryonic calvarial cells, that endogenous CD14 and interleukin-1 beta (IL-1 beta) play an important role in the LPS-mediated bone resorption and that interferon-gamma (IFN-gamma) functions as a strong inhibitor of this resorption by suppressing LPS-stimulated expression of CD14 and IL-1 beta genes in the calvarial cells. We observed that LPS-stimulated differentiation of osteoclastic cells and bone resorption were markedly neutralized by anti-mouse CD14 antibody and were clearly inhibited by anti-sense CD14 oligonucleotide treatment. In addition, because LPS stimulated CD14 gene expression in the calvarial cells, these observations demonstrate the precise role of endogenous CD14 in LPS-stimulated differentiation of osteoclastic cells and bone resorption. However, the stimulation of the differentiation of osteoclastic cells and bone resorption was also inhibited by anti-mouse IL-1 beta antibody. Interestingly, anti-sense CD14 oligonucleotide inhibited LPS-stimulated expression of the IL-1 beta gene in the calvarial cells. These observations suggest a functional role of endogenous CD14 in LPS-stimulated expression of the IL-1 beta gene in the cells. Because IFN-gamma is a potent inhibitor of bone resorption stimulated by IL-1, in additional experiments, we examined whether IFN-gamma is able to inhibit LPS-stimulated differentiation of osteoclastic cells and bone resorption. We found that IFN-gamma inhibited these stimulations by suppressing CD14 and IL-1 beta genes in the calvarial cells. The present study thus clearly demonstrates a functional role of endogenous CD14 in LPS-stimulated bone resorption.

Acid Phosphatase↗
PubMed1997

Identification of endogenous substrates for Drosophila calpain from a salt-extracted fraction of Drosophila ovaries.

Drosophila calpain (Dm-calpain) produced in Escherichia coli has a distinct Ca2+-dependent activity. By using a recombinant Dm-calpain, we searched for its substrates occurring in Drosophila ovaries, where Dm-calpain is expressed. Among a number of major proteins, several proteins in a salt-extracted fraction were selectively degraded by Dm-calpain in a Ca2+-dependent manner. The major substrates were identified by microsequencing the lysylendopeptidase-digested proteins. Three ribosomal proteins, the L5, L7, and L8 subunits of the 60S ribosome, were found to be potential Dm-calpain substrates. In addition, the alpha subunit of elongation factor-1 (EF-1alpha), a multi-functional protein involved in both protein synthesis and cytoskeletal regulation, was shown to be cleaved by Dm-calpain into several distinct fragments when expressed as a GST-fusion protein. Endogenous EF-1alpha in ovary extracts was also shown by western blot analysis to be similarly degraded. These observations suggest that Dm-calpain may regulate protein synthesis and cytoskeletal structure through its degradative or processing activity.

Amino Acid Sequence↗
PubMed1997

Premature termination codon mutations in the type VII collagen gene in recessive dystrophic epidermolysis bullosa result in nonsense-mediated mRNA decay and absence of functional protein.

The severe mutilating Hallopeau-Siemens type of recessive dystrophic epidermolysis bullosa (HS-RDEB) is characterized by the absence of anchoring fibrils that consist of type VII collagen. We have previously identified premature termination codon (PTC) mutations in both alleles of the type VII collagen gene (COL7A1) in HS-RDEB patients. In this study we have defined the mechanism by which these mutations elicit their phenotypic consequences in a family. The extent of nonsense-mediated mRNA decay induced by these mutations was assessed by quantitation of the level of expression of the corresponding mRNA from each of the mutant alleles by RT-PCR of parental RNA. The level of expression of the paternal mutant allele with a PTC in exon 2 was approximately 30% of that of the wild-type allele whereas that of the maternal mutant allele with a PTC in exon 104 was reduced to about 80% of the normal allele. Immunoprecipitation of newly synthesized type VII collagen with a monoclonal antibody revealed reduced quantities of alpha1(VII) polypeptides in both parents' cells, whereas their synthesis was entirely absent in the proband's keratinocytes. Thus, a consequence of these premature termination codon mutations in COL7A1 is nonsense-mediated mRNA decay, with a dramatic reduction in type VII collagen synthesis, and the absence of anchoring fibrils in the proband. These results establish a mechanistic link between the presence of premature termination codon mutations in both alleles of COL7A1 and the clinical phenotype of HS-RDEB.

Alleles↗
PubMed1997

[Effects of topical corticosteroids on subepithelial haze after excimer laser corneal surgery--objective and quantitative method for evaluating haze].

To examine the effectiveness of topical corticosteroids in decreasing subepithelial haze induced by excimer laser keratectomy, we performed excimer laser keratectomy on 24 eyes of 12 albino rabbits using a scanning excimer laser system (EC-5000, NIDEK, Japan). Topical dexamethasone 0.1% was applied topically to 8 corneas after surgery (steroid group), but not to the others (control group). Slit-lamp biomicroscopic examination and objective measurement of scattered light from subepithelial haze were performed before and 2, 4, 8 and 12 weeks after surgery, the rabbits were killed after 2 or 12 weeks and the eyes were examined histologically. In both groups, densitometric values of scattered light intensity increased up to 4 weeks after surgery, and then decreased gradually. However, the values of the steroid group were larger than those of the control group at all stages, and the values of the steroid group at 12 weeks after surgery were similar to preoperative values. There was statistically significant difference in scattered light intensity between the two groups (p < 0.005). Two weeks after surgery, the corneas of the control group showed epithelial hyperplasia and a remarkable increase in activated keratocytes and subepithelial fibrous tissues. However, in the steroid group these light microscopic findings could not be observed. At 12 weeks after surgery, the corneas of the control group retained a small amount of activated keratocytes and fibrous tissues, and those of the steroid group were normal. This study suggests that a short course of topical corticosteroids may be very effective in decreasing subepithelial haze after excimer laser corneal surgery.

Administration, Topical↗
PubMed1997

High performance seizure-monitoring system using a vibration sensor and videotape recording: behavioral analysis of genetically epileptic rats.

A new seizure-monitoring apparatus containing a piezoceramic vibration sensor combined with videotape recording was developed. Behavioral analysis of Ihara's genetically epileptic rat (IGER), which is a recently developed novel mutant with spontaneously limbic-like seizures, was performed using this new device. Twenty 8-month-old male IGERs were monitored continuously for 72 h. Abnormal behaviors were detected by use of a vibration recorder, and epileptic seizures were confirmed by videotape recordings taken synchronously with vibration recording. Representative forms of seizures were generalized convulsions and circling seizures. Generalized convulsions were found in 13 rats, and circling seizures in 7 of 20 animals. Two rats had generalized and circling seizures, and two rats did not have seizures. Although there was no apparent circadian rhythm to the generalized seizures, circling seizures occurred mostly between 1800 and 0800 h. A correlation between the sleep-wake cycle and the occurrence of circling seizures seems likely. Without exception, all the seizure actions were recorded by the vibration recorder and the videotape recorder. To eliminate the risk of a false-negative result, investigators scrutinized the information obtained from the vibration sensor and the videotape recorder. The newly developed seizure-monitoring system was found to facilitate detailed analysis of epileptic seizures in rats.

Animals↗
PubMed1997

Extrasynaptic location of laminin beta 2 chain in developing and adult human skeletal muscle.

We have investigated the distribution of the laminin beta 2 chain (previously s-laminin) in human fetal and adult skeletal muscle and compared it to the distribution of laminin beta 1. Immunoblotting and transfection assays were used to characterize a panel of monoclonal and polyclonal antibodies to the laminin beta 2 chain. We found that laminin beta 1 chain was detected at all times during development from 10 weeks of gestation. Laminin beta 2 chain was first detected in 15 to 22-week-old fetal skeletal muscle as distinct focal immunoreactivity in the sarcolemmal basement membrane area of some myofibers. In the adult skeletal muscle, laminin beta 2 chain immunoreactivity was found along the entire perimeter of each of the individual myofibers in a large series of different muscles studied. Laminin beta 2 chain was similarly found in the skeletal muscle basement membranes in patients with Duchenne and Becker muscular dystrophy. Immunoaffinity chromatography of muscle extracts with a monoclonal antibody to the laminin alpha 2 chain followed by immunoblotting with various antibodies to the beta 2 chain demonstrated the presence of the laminin-4 (alpha 2-beta 2-gamma 1) isoform. Together the present results demonstrate a prominent extrasynaptic localization of laminin beta 2 in the human muscle, suggesting that it may have an important function in the sarcolemmal basement membrane.

Adult↗
PubMed1997

[A case of adult-onset neurenteric cyst presenting as chronic progressive muscular atrophy in lower legs].

A 50-year-old man was admitted, because of motor weakness of the lower limbs, dysesthesia of the left lower extremity, and anuresis. He had an episode of pain in his gluteal region 17 years ago, and then, no abnormalities were detected including myelography in a hospital, followed by slowly progressive muscular atrophy of his lower legs. At 50 years of age, dysuria appeared. He was diagnosed as having neurogenic bladder by urologists, and was admitted to our hospital. On admission, abnormal neurologic findings included: severe muscular atrophy in his lower legs, pes cavus, dysesthesia at the left S1 level, and autonomic bladder. Magnetic resonance imaging (MRI) showed mass lesion involving lower conus and cauda equina. After resection, pathological study revealed the mass was a neurenteric cyst. It is said that the neurenteric cyst causes an asymmetrical and sequential loss of specific neurological functions, with a subsequent return of these functions in the reverse order. That mechanism is not clear. However, in our case, the course of the illness was slowly progressive. We speculate that, because of the cyst's adhesion to cauda equina and perforation through the cyst by a nerve root, the cyst was fixed and caused slowly progressive neurological deficits in proportion to increase of the cyst's size. Our report suggests that a neurenteric cyst, involving the lower conus and cauda equina, can produce severe muscular atrophy in the lower legs.

Age Factors↗
PubMed1997

[An adult case of Williams-Campbell syndrome associated with pulmonary hypertension and a severe decrease in ventilatory response].

Williams-Campbell syndrome is a unique form of bronchiectasis caused by a congenital defect in bronchial cartilage, and is rare in Japan. A 34-year-old man was admitted to our hospital with a fever, and a productive cough. Arterial blood gas analysis revealed severe type II-respiratory failure. Many thin-walled cystic shadows (5-60 mm in diameter) were present in the entire lung field. Pulmonary function tests revealed obstructive impairment. Bronchograms demonstrated cystic bronchiectasis, with ballooning on inspiration and collapse on expiration, characteristic of Williams-Campbell syndrome. Despite severe hypoxia, he did not suffer from dyspnea. We examined ventilatory response to hypercapnea (HCVR) and hypoxia (HVR), and both HCVR and HVR were abnormal. In addition, the mean pulmonary artery pressure was 26 mmHg, indicating pulmonary hypertension.

Adult↗
PubMed1996

Primary sequences of rat mu-calpain large and small subunits are, respectively, moderately and highly similar to those of human.

cDNAs for rat mu-calpain large subunit and the calpain small subunit were cloned and sequenced. The large subunit encodes 713 amino-acid residues, which includes one deletion compared to that of human. The overall similarity is 89% to human mu-type, which is slightly lower than those compared between other types of calpain large subunits of rat and human (93-94%). On the other hand, the small subunit showed high conservation, being 94.0% identical to that of human. With these sequences, primary structures of all rat calpain subunits that have been considered to exist were completely elucidated.

Amino Acid Sequence↗
PubMed1996

Reactive oxygen intermediates increase vascular endothelial growth factor expression in vitro and in vivo.

Elevated vascular endothelial growth factor (VEGF) levels are required for ocular and tumor angiogenesis in animal models. Ischemic hypoxia is strongly correlated with increased VEGF expression in these systems and is considered a physiologically relevant stimulus. Because ischemic hypoxia is often followed by reperfusion and reactive oxygen intermediate (ROI) generation, we examined the potential role of ROI in the control of VEGF gene expression. Human retinal pigment epithelial cells exposed to superoxide or hydrogen peroxide rapidly increased VEGF mRNA levels. Superoxide-associated mRNA increases were dose dependent, blocked by antioxidants, and associated with elevated VEGF protein levels in conditioned media. Increases in VEGF mRNA levels were also observed in cultured human melanoma and rat glioblastoma cells with superoxide or hydrogen peroxide. Cycloheximide prevented the ROI-associated increases in VEGF mRNA. Transcriptional inhibition with actinomycin D revealed an inducible increase in VEGF mRNA half-life, but nuclear run-on experiments showed no increase in VEGF transcriptional rate. Reoxygenation of human retinal pigment epithelial cells in vitro and ocular reperfusion in vivo increased retinal VEGF mRNA levels. Antioxidants prevented the reperfusion-associated VEGF mRNA increases in retina. We conclude that ROIs increase VEGF gene expression in vitro and during the reperfusion of ischemic retina in vivo. The ROI-associated increases are mediated largely through increases in VEGF mRNA stability.

Animals↗
PubMed1996

Loss of plectin causes epidermolysis bullosa with muscular dystrophy: cDNA cloning and genomic organization.

Plectin is a widely expressed high molecular weight protein that is involved in cytoskeleton-membrane attachment in epithelial cells, muscle, and other tissues. The human autosomal recessive disorder epidermolysis bullosa with muscular dystrophy (MD-EBS) shows epidermal blister formation at the level of the hemidesmosome and is associated with a myopathy of unknown etiology. Here, plectin was found to be absent in skin and cultured keratinocytes from an MD-EBS patient by immunofluorescence and immunoprecipitation, suggesting that plectin is a candidate gene/protein system for MD-EBS mutation. The 14800-bp human plectin cDNA was cloned and sequenced. The predicted 518-kD polypeptide has homology to the actin-binding domain of the dystrophin family at the amino terminus, a central rod domain, and homology to the intermediate filament-associated protein desmoplakin at the carboxyl terminus. The corresponding human gene (PLEC1), consisting of 33 exons spanning >26 kb of genomic DNA was cloned, sequenced, and mapped to chromosomal band 8q24. Homozygosity by descent was observed in the consanguineous MD-EBS family with intragenic plectin polymorphisms. Direct sequencing of PCR-amplified plectin cDNA from the patient's keratinocytes revealed a homozygous 8-bp deletion in exon 32 causing a frameshift and a premature termination codon 42 bp downstream. The clinically unaffected parents of the proband were found to be heterozygous carriers of the mutation. These results establish the molecular basis of MD-EBS in this family and clearly demonstrate the important structural role for plectin in cytoskeleton-membrane adherence in both skin and muscle.

Actins↗
PubMed1996

Prostaglandin E2 stimulates osteoclast formation via endogenous IL-1 beta expressed through protein kinase A.

The present study was conducted to determine whether endogenous IL-1 is involved as a potent mediator of PGE2-stimulated osteoclast formation in 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25-(OH)2D3)-primed calvarial cells from mouse embryos. PGE2 induced IL-1 beta gene expression in the primed calvarial cells. IL-1 beta gene expression was also induced in a dose-dependent manner by forskolin and dibutyryl cAMP. PGE2-induced IL-1 beta gene expression was markedly inhibited by H-89, a potent inhibitor of protein kinase A. On the other hand, osteoclast formation in 1 alpha,25-(OH)2D3-primed calvarial cells was also stimulated by forskolin and dibutyryl cAMP, and their stimulatory effects were dose dependent. H-89 also inhibited PGE2-stimulated osteoclast formation. The presence of the IL-1 beta gene product in the conditioned medium of 1 alpha,25-(OH)2D3-primed calvarial cells treated with PGE2 was proved by the results of an immunoprecipitation assay using anti-mouse IL-1 beta Ab. The addition of anti-mouse IL-1 beta Ab to 1 alpha,25-(OH)2D3 primed calvarial cell cultures markedly inhibited PGE2-stimulated osteoclast formation. The stimulatory effect of conditioned medium of primed calvarial cells treated with PGE2 on osteoclast formation was also inhibited by anti-IL-1 beta Ab pretreatment. Furthermore, we found that endogenous IL-6 is partially involved in PGE2-stimulated osteoclast formation.

24,25-Dihydroxyvitamin D 3↗
PubMed1996

Compound heterozygosity for COL7A1 mutations in twins with dystrophic epidermolysis bullosa: a recessive paternal deletion/insertion mutation and a dominant negative maternal glycine substitution result in a severe phenotype.

We have previously demonstrated genetic linkage between the type VII collagen gene (COL7A1) and the dominant (DDEB) and recessive (RDEB) forms of dystrophic epidermolysis bullosa (DEB) and have subsequently identified pathogenetic mutations in several families. Mutations in DDEB identified thus far are glycine substitutions in the collagenous domain of COL7A1, while the most severe forms of RDEB result from premature termination codon (PTC) mutations on both alleles. In this study, we performed mutation analysis in the COL7A1 gene in twins who displayed a severe DEB phenotype. Mutational analysis revealed a paternal 2-bp deletion/1-bp insertion in exon 56, designated 5103CC-->G, which results in a frameshift and downstream PTC. Analysis of the maternal COL7A1 allele revealed a glycine-to-arginine substitution in exon 91 (G2351R). Careful questioning of the mother revealed that she and her father had a history of shedding of toenails and occasional poorly healing erosions, consistent with a mild form of DDEB. Immunoprecipitation of type VII collagen from fibroblasts of the twins revealed a marked reduction in intracellular protein production, consistent with the drastic reduction in mRNA transcript from the paternal mutant allele, while the majority of polypeptides bearing the glycine substitution appeared to be degraded intracellularly. Thus, the severe RDEB phenotype in the probands results from compound heterozygosity for one glycine substitution and one PTC mutation in COL7A1.

Base Sequence↗
PubMed1996

Development of a novel rat mutant with spontaneous limbic-like seizures.

A new epileptic rat mutant with spontaneous seizures was developed by successive mating and selection from an inherited cataract rat. The procedures for developing the mutant and the symptomatology, electroencephalographic correlates, and neuropathology of the mutant are reported. It is possible that this rat stain will provide a useful animal model for human temporal lobe epilepsy. The seizures of the rat usually begin with face and head myoclonus, followed by rearing, and generalized clonic and tonic convulsions, all of which are symptomatologically the same as limbic seizures. Electrographic recording during generalized convulsive seizures demonstrated that sustained spike discharges emerged at the hippocampus and then propagated to the neocortex. Seizures occurred spontaneously without any artificial stimuli. Furthermore, external stimuli such as auditory, flashing light, or vestibular stimulations could not elicit epileptic attacks. Almost all of the male animals had generalized convulsions, mostly from 5 months after birth, and the frequency of the seizures increased with aging. Generalized convulsions developed in approximately 20% of the female rats. Microdysgenesis, such as abnormal neuronal clustering, neuronal disarrangement, or interruption of pyramidal neurons in the hippocampal formation, was found in the young rats that had not yet had generalized seizures. This microdysgenesis, which is though to be genetically programmed, was very interesting from the aspect of the relationship between structural abnormalities and epileptogenesis in this mutant. In addition to microdysgenesis, there was sprouting of mossy fibers into the inner molecular layer of the dentate gyrus in those adult rats that had repeated generalized convulsions. An increase of glial-fibrillary-acidic-protein-positive astrocytes with thickened and numerous processes, ie, astrogliosis, was also found in the cerebral cortex, amygdala region, and hippocampus of these adult animals. Judging from the characteristics of the symptomatology, electroencephalographic correlates, and neuropathology, this epileptic mutant can be expected to be a useful animal model for studying human temporal lobe epilepsy.

Aging↗