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Biomedical subjects

Y Kawakita

Publications and source records attributed to Y Kawakita.

At least 19 recordsLinked to original sources
PubMed2002

Radioiodination of glycoprotein-conjugated liposomes by using the Bolton-Hunter reagent and biodistribution in tumor-bearing mice.

We have developed a suitable radiolabeling method for our new type of glycoprotein-liposome conjugate (GCL), in order to investigate its potential utility as a drug carrier that can target the cellular functions of carbohydrate-binding proteins. In order to obtain radiolabeled GCL with high labeling efficiency, we introduced p-hydroxyphenylpropyl groups into the liposome membrane through the amine moiety of a constitutive phospholipid, dipalmitoylphosphatidylethanolamine (DPPE) by using Bolton-Hunter reagent (BHR). Radioiodination of the introduced tyrosyl groups was performed by the Chloramine-T method. The labeling efficiency of the BHR-treated liposome conjugate was high in comparison with that of the BHR-untreated liposome conjugate. An in vitro inhibition study showed that the binding affinity of 125I-labeled BHR-treated GCL (125I-F3S-BH) with lectin was twice as high as that of untreated conjugate (125I-F3S). The biodistribution of 125I-F3S-BH in mice was considerably different from that of 125I-F3S. 125I-F3S-BH was more rapidly taken up by the liver and was more rapidly excreted from the liver than 125I-F3S. Moreover, 125I-F3S-BH accumulated more rapidly into the kidneys, which resulted a lower radioactivity in the blood circulation at an earlier time point than in the case of 125I-F3S. The characteristics of tumor accumulation of 125I-F3S-BH and 125I-F3S were similar to those in blood. If F3S is to be employed as an in vivo targeting ligand in biodistribution studies, BHR would be a suitable tool for radiolabeling because it allows GCL to retain the biological activity and characteristics of the unmodified conjugate.

Animals↗
PubMed1998

Prenatal diagnosis of Fukuyama type congenital muscular dystrophy in eight Japanese families by haplotype analysis using new markers closest to the gene.

We conducted prenatal diagnosis by haplotype analysis, using newly developed microsatellite markers, in eight Fukuyama type congenital muscular dystrophy (FCMD) families. In addition to six new families, two previously reported families were reexamined by haplotype analysis including detection of an ancestral founder haplotype (138-183-301) for 3 microsatellite markers closest to the FCMD gene, designated D9S2105-D9S2107-D9S172, the distances of which from the FCMD gene are presumed to be approximately 140, approximately 20, and approximately 280 kb, respectively. Five fetuses from five families were diagnosed as nonaffected, and were subsequently confirmed to be healthy. Three fetuses of the other three families were diagnosed as having a high probability of being affected by FCMD. In the prenatal diagnosis conducted for these eight families, the ancestral founder allele was observed in 13 of 16 (81%) FCMD-bearing chromosomes. Detection of the ancestral haplotype facilitated achieving accurate prenatal diagnosis of FCMD. The brains of all three fetuses prenatally diagnosed as FCMD-affected showed the initial stage of cortical dysplasia, strong evidence of FCMD.

Brain↗
PubMed1998

Comparison of amino acid sequence of the C-terminal domain of insulin-responsive glucose transporter (GLUT4) in livestock mammals.

The nucleotide sequence of cDNA coding the 38-amino acid of the C-terminal domain of insulin-responsive glucose transporter (GLUT4) was determined by the method of reverse transcription-polymerase chain reaction in the sheep, goat and pig, and compared with that of bovine which have been shown to have a unique amino acid conversion of Asn508 to His. The deduced amino acid sequence was completely identical in the three species, and did not have the amino acid conversion at position 508. Western blot analysis confirmed that an antiserum raised against a rat C-terminal peptide cross-reacted efficiently with GLUT4 of these livestock mammals.

Amino Acid Sequence↗
PubMed1997

Dietary skim milk powder increases ionized calcium in the small intestine of piglets compared to dietary defatted soybean flour.

Calcium distribution was studied in the small intestine of piglets fed skim milk powder (SMP) or defatted soybean flour (DSF ) to investigate the relationship between calcium availability and its forms. Ionized calcium in duodenal and ileal digesta was measured with a selective calcium electrode that was not affected by changes in pH or sodium, potassium and magnesium concentrations, which simulated the liquid phases of digesta. Eight piglets were fed DSF-based diet or SMP-based diet for 30 d, and duodenal and ileal digesta were collected. Soluble calcium concentrations in the ileum were higher in the SMP-fed group than in the DSF-fed group. The proportion of soluble calcium in higher-molecular-weight fraction (MW > 3000) was significantly greater in the ileum than in the duodenum of the SMP group, but did not differ between these intestinal segments within the DSF group. This proportion was significantly higher in the ileum of the SMP-fed group than in that of the DSF-fed group. In the ileum, ionized calcium concentration was significantly greater in the SMP-fed group than in the DSF-fed group. These results suggest that the increase of calcium in the higher-molecular-weight fraction raises soluble calcium concentration and changes the distribution of calcium in the ileum of the SMP-fed group. The complexes of calcium with higher-molecular-weight ligands may be easily exchangeable with ionized calcium, and the increase in these calcium complexes may consequently enhance the recruitment of ionized calcium, which then can be absorbed.

Animals↗
PubMed1993

Scheduled feeding caused activation of dopamine metabolism in the striatum of rats.

The effects of a time-restricted feeding schedule on dopamine (DA) release and its metabolites output in the striatum of freely moving rats were studied. Rats had access to food for only 2 h daily for 7 successive days. On the 1st or 7th day, the extracellular concentrations of DA, 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) in the ventrolateral striatum were measured by in vivo brain microdialysis during 2 h of exposure to food-related stimuli followed by 2 h of access to food. Extracellular concentrations of DA and its metabolites did not change during the period of exposure to food-related stimuli or during feeding on the 1st day. On the 7th day, extracellular DOPAC and HVA concentrations increased significantly during 2 h of feeding, but not during exposure to food-related stimuli, compared with basal levels. Extracellular DA concentration did not change significantly. These results indicate that scheduled feeding caused activation of DA metabolism in the ventrolateral striatum and facilitate feeding-related motor activity in feeding behavior.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

Effects of morphine and D-Ala2-D-Leu5-enkephalin in the seizure-susceptible El mouse.

Opioid agonists were used to investigate the modulation of seizures in the seizure-susceptible El mouse. Morphine and D-Ala2-D-Leu5-enkephalin (DADLE) were injected subcutaneously or intracisternally as prototypic agonists for mu and delta opioid receptors. Systemic or intracisternal injection of both morphine and DADLE decreased the incidence of seizures and the seizure score in El mice in a dose-dependent manner. The anticonvulsant effects of morphine and DADLE were reversed by naloxone (2 mg/kg, s.c.). This implies that opioid agonists have anticonvulsant properties which are mediated by mu and delta opioid receptors. In conclusion, a deficit in endogenous opioid peptides, which act as anticonvulsants may play a significant role in the etiology or pathophysiology of seizures in the El mouse.

Animals↗
PubMed1992

Reduced bone density and major hormones regulating calcium metabolism in anorexia nervosa.

Bone density of lumbar vertebrae (L2 to L4) and the whole body in 29 patients with anorexia nervosa were measured by dual photon absorptiometry, and the results were compared with those of 10 age-matched normal controls. The patients had significantly lower bone mineral density (BMD) in L3 and L2-4 than controls. However, there was no difference in whole-body BMD. L3 and L2-4 BMD was positively correlated with body weight and was negatively correlated with duration of illness and amenorrhea. Patients who had been more active 6 months before the time of the study had significantly higher L3 BMD than the less active patients. Most patients had an abnormally low serum estrogen level, whereas the mean serum levels of thyroid hormone (T3, T4), cortisol, calcitonin, parathyroid hormone and vitamin D were within the normal range. No correlation was found between L3 or L2-4 BMD and the levels of these hormones. These results suggest that severe weight loss, low physical activity, longer duration of amenorrhea and deficiency of estrogen contribute to bone loss in patients with anorexia nervosa, whereas calcium-regulating hormones such as parathyroid hormone, calcitonin and vitamin D are unlikely to be a primary contributor to bone loss.

Adolescent↗
PubMed1990

Developmental and regional alteration of methionine enkephalin-like immunoreactivity in seizure-susceptible E1 mouse brain.

Methionine enkephalin-like immunoreactivity (ME-LI) in the brain of El mice (seizure-susceptible strain) was measured by radioimmunoassay (RIA) to elucidate the relation between seizures and the opioid system. The lyophilized supernatants of tissue extracts were subjected to ME RIA. The concentration of ME-LI in 25-day-old El mice that had no seizures was significantly decreased in the hippocampus. At the age of 50 days when El mice displayed abortive seizures, the levels of ME-LI in both El(+) and nonstimulated El(o) mice were also significantly reduced in the hippocampus and septal area. It was further shown that the ME-LI concentrations in both 150-day-old adult El(+) during interictal periods and El(o) mice were markedly decreased in the cerebral cortex, septal area, and striatum, as compared with the corresponding regions in ddY mice (seizure-nonsusceptible strain; the mother strain of El). The decrease of ME-LI in the El mouse brain was generally compatible with our previous findings concerning the up-regulation of opioid delta receptors in this species. These results suggest that the reduction of ME-LI in the El mouse brain is not due to convulsions, but could be associated with the pathogenesis of seizure diathesis and seizure manifestations in the El mouse.

Animals↗
PubMed1990

Ventricular enlargement in normal weight bulimia.

Cranial computed tomography (CT) scans of 17 patients with bulimia were compared with those of 21 age- and sex-matched controls. The ventricular brain ratio (VBR) of the bulimics was 7.29, which was significantly greater than the 4.55 seen in controls. However, no correlation was found between VBRs and clinical variables, endocrine or metabolic parameters.

Adolescent↗
PubMed1990

Insulin sensitivity in patients with anorexia nervosa and bulimia.

Insulin sensitivity was studied using the euglycemic insulin clamp technique in 5 female patients with anorexia nervosa and 4 females with bulimia. The results were compared with those of 15 male patients with non-insulin-dependent diabetes mellitus. Euglycemic insulin clamp is performed for 2 h using the Biostator, during which time insulin was infused at a rate of 0.77 mU kg-1 min-1. Fasting plasma glucose and immunoreactive insulin tended to be lower in patients with anorexia nervosa than in those with bulimia (69.8 +/- 6.7 vs 75.9 +/- 7.7 mg/dl, and 5.9 +/- 2.0 vs 9.8 +/- 3.4 U/ml). The mean metabolic clearance rate (MCR) was 9.2 +/- 3.9 ml kg-1 min-1 for patients with anorexia nervosa, 5.1 +/- 2.2 ml kg-1 min-1 for patients with bulimia, and 3.8 +/- 0.3 ml kg-1 min-1 for patients with diabetes mellitus. However, one anorectic had a significantly high MCR. One anorectic and 3 bulimics had a significantly low MCR. These results suggest that insulin sensitivity varied in patients with anorexia nervosa, whereas it tended to decrease in some patients with bulimia but not to the same degree as in patients with diabetes mellitus.

Adult↗
PubMed1989

Alteration of opioid receptors in seizure-susceptible El mouse brain.

The distribution density of opioid receptors in the brain of El mice (seizure-susceptible strain) was examined to determine the relation between seizures and the opioid system. Saturation curves and Scatchard plots of [3H]2-D-alanine-5-D-leucine enkephalin binding revealed that the opioid delta receptor density in adult El mice during interictal periods was significantly increased in the cerebral cortex, hippocampus, and septal area. It was further shown that the concentration of such receptors in 25-day-old El mice that had no seizures was also significantly increased in the hippocampus and septal area, with no changes in apparent affinities, as compared with in the corresponding regions in ddY mice (seizure-nonsusceptible strain; the mother strain of El). Such up-regulation of opioid receptors in the El mouse brain could result from deficits in endogenous opioid peptides, which could be associated with the pathogenesis of seizure diathesis in the El mouse.

Animals↗
PubMed1989

Alterations in polyadenylic acid-containing messenger RNA synthesis of brain polysomes after seizures of seizure-susceptible E1 mice.

The effect of seizures on synthesis of the polyadenylic acid (poly(A]-containing messenger RNA (mRNA) isolated from brain polysomes in a genetically seizure-susceptible E1 mouse was studied in vivo. The seizure in the E1 mice was induced by tossed-up stimulation. Immediately after the seizure ceased, the labeled orotic acid was injected into the brain. The incorporation rates of labeled orotic acid into poly(A)-containing mRNA isolated from polysomes are represented as the specific radioactivity (SR) (dpm/mg RNA) and the relative specific radioactivity (RSR) (dpm/mg RNA/dpm/mumoles of acid soluble uridine-5'-monophosphate (UMP]. Both the rates were reduced to 70% in SR and 65% in RSR at 1 h after the seizures. This reduction was gradually recovered to the level of interictal E1 mice at 6 h. The seizure-induced alterations are not attributable to the difference in the uridine nucleotide pool because the SR of UMP was not significantly affected by the seizure. The peak of labeled poly(A)-containing mRNA by analysis of gel electrophoresis displaced towards a lower molecular weight at 1 h after the seizures. The RNA showed a higher ratio of AMP and UMP per GMP and CMP in nucleotide composition, implying that this RNA is identical with DNA. These results suggest that the temporary decrease found in cytoplasmic mRNA synthesis induced by the seizures of E1 mice appears to be a result of impaired transcriptional processes in heterogeneous nuclear RNA synthesis and that the smaller mRNA coding for protein associated with seizures is newly synthesized during the postictal period.

Animals↗