Biomedical subjects

M Nakazato

Publications and source records attributed to M Nakazato.

At least 37 records · Page 2Linked to original sources

PubMed2001

Ghrelin in domestic animals: distribution in stomach and its possible role.

Ghrelin, a novel growth-hormone-releasing acylated peptide, was recently isolated from rat and human stomachs. In rat, peripheral or central administration of ghrelin stimulates the secretion of growth hormone (GH) from the pituitary gland. Recent work suggests that ghrelin plays an important role in energy homeostasis, body weight, and food intake. We examined the distribution of cells immunoreactive to ghrelin in the stomachs of domestic animals and rats, using a polyclonal antibody for the N-terminal fragment of rat ghrelin [1-11]. We measured the plasma levels of ghrelin before and after feeding in cows, and GH levels after central administration of ghrelin in Shiba goats, to elucidate the possible role of ghrelin. Immunostained cells were widely distributed from the neck to the base of the oxyntic gland in all animals. The plasma ghrelin concentration in cows decreased significantly 1 h after feeding, and then recovered to pre-feeding levels. Administration of ghrelin into the third ventricle in Shiba goats dramatically increased the plasma GH concentration dose-dependently. These results suggest that ghrelin plays an important role in GH secretion and feeding regulation in domestic animals.

Animals↗

PubMed2001

Uroguanylin level in umbilical cord blood.

BACKGROUND: Uroguanylin is a novel natriuretic and diuretic peptide originally isolated from urine. METHODS: To determine whether uroguanylin has a physiologic role during the perinatal period, uroguanylin levels in umbilical cord plasma obtained at the time of delivery were measured by radioimmunoassay and compared with cord serum osmolality. RESULTS: Mean (+/- SD) cord plasma uroguanylin concentrations (8.8 +/- 2.1 fmol/mL) were higher compared with normal adult values. The extent of maturity, mode of delivery and gender did not appear to influence cord uroguanylin levels. The uroguanylin concentration had a significant positive correlation with cord serum osmolality. CONCLUSION: These findings support some regulatory role of this peptide in perinatal renal and cardiovascular adaptation.

Fetal Blood↗

PubMed2001

A case of late onset cardiac amyloidosis with a new transthyretin variant (lysine 92).

A new transthyretin (TTR) variant (lysine 92), which causes late onset cardiac amyloidosis, is described in a 71-year-old man. The patient at first had syncope due to ventricular tachycardia and was admitted our hospital. Typical findings of cardiac amyloidosis were observed by echocardiography, and a diagnosis of systemic amyloidosis was made by rectal biopsy. The man died approximately 3 years and 6 months after first admission, with gradually worsening congestive heart failure. Pathological examination showed prominent amyloid deposits in the heart and the vascular wall of many organs including the liver, pancreas, kidney, lung, and gastrointestinal tracts. Amyloid protein of transthyretin type was indicated by immunohistochemical study, and DNA sequencing identified a novel mutation in the transthyretin gene encoding 92 glutamine --> lysine. A polymerase chain reaction-induced mutation restriction analysis with a mismatched antisense primer showed that the patient was heterozygous for the TTR Lys92 allele.

Adult↗

PubMed2001

Nucleotide sequence and expression of rat beta-defensin-1: its significance in diabetic rodent models.

beta-Defensins are epithelium-derived antimicrobial peptides that function in the host's innate defense. We identified the first member of the rat beta-defensin family, beta-defensin-1 (BD-1), in the kidney and determined its nucleotide sequence. It was predicted to be a 37-amino-acid peptide. Rat BD-1 mRNA was expressed most abundantly in the kidney, next in skin, tongue, esophagus, and uterus, followed (at low levels) by brain, trachea, stomach, urinary bladder, and ovary. BD-1 gene expression in rat kidney was not increased by lipopolysaccharide administration. BD-1 gene expressions in the kidneys of diabetic rodent models, cholecystokinin-insensitive Otsuka Long-Evans Tokushima Fatty rats, leptin-insensitive obese (fa/fa) Wistar rats, and db/db mice, were significantly lower than those of their lean littermates. BD-1 reduction may be in part responsible for the high incidence of urinary tract infections in diabetes mellitus.

Amino Acid Sequence↗

PubMed2001

Plasma and BAL fluid concentrations of antimicrobial peptides in patients with Mycobacterium avium-intracellulare infection.

STUDY OBJECTIVES: To investigate the roles of human alpha-defensin (HAD), human beta-defensin (HBD)-1, and HBD-2, novel antimicrobial peptides, in patients with Mycobacterium avium-intracellulare infection (MAI). PATIENTS: The study included 25 patients (10 men) with MAI who visited our hospital between June 1998 and August 1999. MEASUREMENTS AND RESULTS: In patients with pulmonary MAI, we measured HAD and HBD-1, and HBD-2 levels in plasma and in BAL fluid (BALF) by radioimmunoassay. Plasma concentrations of HAD and HBD-2 in those patients were higher than those in control subjects, whereas HBD-1 levels were similar to those in the control subjects. High levels of HAD and HBD-2, but not HBD-1, also were observed in the BALF of MAI patients. There was a positive correlation between HAD and interleukin (IL)-8 concentrations in the BALF of patients with MAI. BALF HBD-2 concentrations also correlated positively with those of plasma HBD-2 and BALF IL-1 beta in MAI patients. Patients with cavity formation on the chest roentgenogram had higher HAD and HBD-2 levels in their BALF than those of patients without cavity formation. Treatment with clarithromycin combined with two or three other antibiotics, including ethambutol, rifampicin, ofloxacin, or ciprofloxacin, for at least 6 months resulted in a significant fall in plasma HBD-2 concentrations in responders, but not in nonresponders. CONCLUSION: Our findings suggest that HAD and HBD-2 may participate in host defense and local remodeling of the respiratory tract in patients with MAI and that plasma HBD-2 levels may be a useful marker of disease activity in patients with pulmonary MAI.

Anti-Bacterial Agents↗

PubMed2001

[Aged onset of amyloidosis caused by transthyretin gene mutations].

We have identified that familial amyloid polyneuropathy with middle age onset results from missense mutations of the transthyretin gene. In the present study, we investigated molecular abnormalities of transthyretin in elderly patients with cardiac amyloidosis or amyloid polyneuropathy, using DNA sequencing and protein sequencing. We detected 5 cases of transthyretin-related cardiac amyloidosis using immunohistochemical techniques. All of them had late-onset, mild or no peripheral neuropathy or autonomic dysfunctions, and no family history. Three had transthyretin Met30 and two transthyretin Ile50. We also found 15 patients with transthyretin-related amyloid polyneuropathy. All of them had late-onset and no contributory family history. Twelve had transthyretin Met30, two transthyretin Ile50, and one transthyretin Ser109. Clinical manifestations and sequencing procedures of six representative patients were also presented. Molecular investigation of transthyretin is needed for elderly patients with etiology-unknown cardiac amyloidosis or amyloid polyneuropathy even if there is no family history of amyloidosis.

Aged↗

PubMed2001

[Determination of sucralose in foods by HPLC].

A method for the determination of sucralose in various foods by RI-HPLC and ion chromatography with a pulsed amperometric detector (PAD-IC) was developed. Chopped or homogenized samples were packed into cellulose tubing with 0.01 mol/L hydrochloric acid containing 10% sodium chloride and were dialyzed against 0.01 mol/L hydrochloric acid for 24 hours. The dialyzate was passed through a Bond Elut ENV cartridge, and the cartridge was washed with 0.2 mol/L NaOH and water. Sucralose was eluted from the cartridge with methanol. The extract was taken to dryness in an evaporator and the residue was re-dissolved in water. Sucralose was separated on an Inertsil ODS-3V column with a mobile phase of acetonitrile-water (15:85) and an RI detector. It was also determined on a CarboPak PA1 column with a mobile phase of 100 mmol/L NaOH-75 mmol/L CH3COONa, using a PAD detector. The recoveries of sucralose from various kinds of foods spiked at 50 micrograms/g and 200 micrograms/g ranged from 88-105%. The detection limit in samples was 10 micrograms/g for RI-HPLC and 1 microgram/g for PAD-IC.

Chromatography, High Pressure Liquid↗

PubMed2001

[Determination of neohesperidin dihydrochalcone in foods].

An HPLC method was developed for the determination of neohesperidin dihydrochalcone (NHDC) in foods. A solid sample was extracted with methanol. The extract was evaporated and the residue was dissolved in methanol-water (2:8) mixture. In the case of fluid sample, the sample solution was prepared by dilution with methanol-water (2:8) mixture. The sample solution was cleaned up on a C18 cartridge. The cartridge was washed with water and methanol-water (3:7) mixture, and NHDC was eluted with methanol-water (7:3) mixture. NHDC in the eluate was separated on an ODS column and determined with a UV detector (282 nm). The identity of NHDC in foods was confirmed by means of HPLC with a photodiode-array detector. The recoveries of NHDC added to various kinds of foods were 75.2-134%. The determination limit of NHDC was 1 microgram/g.

Chalcone↗

PubMed2001

[A role for orexins and melanin-concentrating hormone in the central regulation of feeding behavior].

The hypothalamus is the most important region in the control of food intake and body weight. The ventromedial 'satiety center' and lateral hypothalamic 'feeding center' have been implicated in the regulation of feeding and energy homeostasis by various studies of brain lesions. Orexins(orexin A and orexin B) and melanin-concentrating hormone (MCH), whose intracerebroventricular injections increase food intake, are localized in the lateral hypothalamus and provide diffuse projections throughout the brain. Orexins and MCH neurons have a coextensive distribution, but are not colocalized. Orexins and MCH may affect feeding behavior through distinct neuronal pathways. We here describe the effect of orexins and MCH on feeding behavior from the physiological, neuroanatomical and molecular studies.

Animals↗

PubMed2001

[Beta-defensins in plasma and bronchoalveolar lavage fluid in patients with non-tuberculous mycobacterium infection].

We measured the levels of beta-defensin 1 and 2 (HBD-1, 2), novel antimicrobial peptides in plasma and in bronchoalveolar lavage fluid (BALF) from patients with with non-tuberculous mycobacterium infection (NTM). Plasma HBD-2 levels in NTM patients before treatment were higher than those in the controls, while the HBD-1 levels were similar to the control levels. High levels of HBD-2, but not of HBD-1, in BALF were also observed in NTM patients. In NTM, a positive correlation was found between HBD-2 levels in BALF and plasma, and also between HBD-2 and IL-1 beta levels in BALF. NTM patients with cavities or ectasia on chest radiography had higher HBD-2 levels in BALF than those without. Plasma HBD-2 levels in NTM patients were markedly decreased after successful treatment, while those of patients with an intractable mycobacterium infection maintained the same high plasma HBD-2 levels as those before treatment. These findings suggest that HBD-2 may participate in the host defense and plasma HBD-2 levels may reflect disease activity in pulmonary NTM.

Biomarkers↗

PubMed2000

Recombinant granulocyte colony-stimulating factor induces production of human neutrophil peptides in lung cancer patients with neutropenia.

Human neutrophil peptides (HNPs) 1, 2 and 3 are antimicrobial peptides localized in the azurophil granules of neutrophils. We investigated the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on the biosynthesis of HNPs 1-3 using a sensitive radioimmunoassay and Northern blot analysis. Seven patients with lung cancer were first treated with various anticancer agents for 3 days (days 1-3) followed by treatment with rhG-CSF (2 microgram/kg weight/day) for 7 days (days 8-14). Chemotherapy caused neutropenia but the neutrophil count increased biphasically between days 8 and 14. Chemotherapy did not change the baseline plasma concentration of HNPs 1-3 (74.1+/-2.1 pmol/ml) but the concentration increased from day 12, 5 days after commencement of rhG-CSF therapy, to reach a peak value of 430.8+/-57.0 pmol/ml on day 15, 1 day after the last administration of rhG-CSF. Baseline HNPs 1-3 content per neutrophil was 0.59+/-0.02 fmol, decreased to 0.30+/-0.07 fmol on day 9, then increased to 0.78+/-0.07 fmol on day 15. Analyses of peripheral blood neutrophils by Northern blot and reverse-phase high-performance liquid chromatography showed that the amounts of HNPs 1-3 mRNA and precursors of HNPs 1-3 markedly increased in response to rhG-CSF. Our results indicate that recombinant hG-CSF does not only increase neutrophil count but stimulates HNPs 1-3 biosynthesis in neutrophils, thus enhancing the host defense system of compromised hosts with neutropenia.

Adenocarcinoma↗

PubMed2000

Class II transactivator suppresses transcription of thyroid-specific genes.

Class II transactivator (CIITA) is the master regulator of MHC class II genes, and mediates their induction by interferon gamma (IFN gamma). To study the role of CIITA in modulating the expression of thyroid-specific genes, we cloned the full-length rat CIITA and use it to transfect a rat thyroid cell line. We found that only one type of CIITA, type IV, is induced in thyroid cells upon IFN gamma stimulation, and that CIITA is capable not only of inducing the expression of MHC genes in the thyroid, but also of differentially suppressing the expression of thyroid-specific genes. These findings suggest new avenues for the development of thyroid autoimmune diseases.

Animals↗

PubMed2000

Both corticotropin releasing factor and neuropeptide Y are involved in the effect of orexin (hypocretin) on the food intake in rats.

Orexin (hypocretin) is a peptide that has been found to stimulate food intake in rats. However, we have recently demonstrated that orexin stimulates the release of corticotropin releasing hormone (CRF) which has been known to decrease the food intake. Therefore, we examined the mechanism of effect of orexin on food intake. Although the other appetite stimulating peptides; neuropeptide Y (NPY), agouti-related peptide (AGRP) and one of the growth hormone releasing secretagogue (GHRP-6) stimulated dose-dependently the food intake during 2 h in the early light period, orexin did not increase significantly the food intake. No significant increase was also observed during 2 h in the early dark period. However, pretreatment with alpha-helical CRF, an antagonist of CRF, or anti-CRF antiserum resulted in significant increase of food intake by orexin. Orexin-stimulated feeding under these conditions was blocked by NPY Y1 receptor antagonist (1229U91). In an 8 h-fasting rat, anti-orexin serum decreased slightly the food intake. These results suggest that effect of orexin on the food intake may be complex because of orexin-CRF and orexin-NPY linkage.

Agouti-Related Protein↗

PubMed2000

Central effects of neuromedin U in the regulation of energy homeostasis.

Neuromedin U (NMU) is a brain-gut peptide whose peripheral activities are well-understood but whose central actions have yet to be clarified. The recent identification of two NMU receptors in rat brain has provided a springboard for further investigation into its role in the central nervous system. Intracerebroventricular administration of NMU to free-feeding rats decreased food intake and body weight. Conversely, NMU increased gross locomotor activity, body temperature, and heat production. NMU, a potent endogenous anorectic peptide, serves as a catabolic signaling molecule in the brain. Further investigation of the biochemical and physiological functions of NMU will help our better understanding of the mechanisms of energy homeostasis.

Animals↗

PubMed2000

Purification and identification of neuromedin U as an endogenous ligand for an orphan receptor GPR66 (FM3).

GPR66 is an orphan G-protein-coupled receptor (GPCR) whose structure is similar to the ghrelin and motilin receptors. We have tried to purify a natural ligand for GPR66 in rat tissues and identified a 23-amino-acid peptide as the endogenous ligand. Sequence analysis revealed the peptide as neuromedin U (NMU), a smooth-muscle-contracting peptide that was first purified from porcine spinal cord by our group. NMU binds to GPR66-expressing cells with high specificity to induce intracellular calcium mobilization. When NMU was injected intracerebroventricularly (ICV) into rats, it potently suppressed food intake. In contrast, ICV injection of NMU-antibody increased food intake. These results suggest that NMU is a potent endogenous anorexic peptide.

Amino Acid Sequence↗

PubMed2000

Central effects of a novel acylated peptide, ghrelin, on growth hormone release in rats.

Ghrelin, a novel growth-hormone-releasing acylated peptide, was recently isolated from rat stomach by the search of an endogenous ligand to an "orphan" G-protein-coupled-receptor. Ghrelin neuron is present in the arcuate nucleus of rat hypothalamus, but its central effect on growth hormone (GH) release has yet to be clarified. We determined the plasma GH concentration and GH mRNA level in the pituitary in response to central administration of ghrelin. A single intracerebroventricular (ICV) administration of ghrelin to rats increased the plasma GH concentration dose-dependently. A continuous ICV administration of ghrelin via osmotic pump for 12 days increased the plasma GH concentration on day 6, but did not keep the high GH concentration on day 12. The GH mRNA levels in both groups of single and continuous administration of ghrelin were not significantly different from those of controls. A single administration of growth-hormone secretagogue also did not stimulate GH synthesis. Central ghrelin stimulated GH release but did not augment GH synthesis. In addition to gastric ghrelin, hypothalamic ghrelin functions to regulate GH release.

Animals↗

PubMed2000

Distribution of orexin-A and orexin-B (hypocretins) in the rat spinal cord.

Orexin-A and orexin-B (also known as hypocretin-1 and hypocretin-2) are hypothalamic peptides that regulate feeding behavior, energy metabolism, and sleep-wake cycle. We determined the distribution of orexin-A and -B in the rat spinal cord, using sensitive radioimmunoassays and an immunohistochemical technique with three antisera specific for these orexins. Orexins were distributed throughout the spinal cord, and their contents were highest in the cervical region. Orexin fibers were concentrated in lamina I of the dorsal horn and area X surrounding the central canal of the spinal cord. Abundant orexin fibers also were present in the preganglionic sympathetic and parasympathetic cell columns. These findings suggest that orexins in the spinal cord may be involved in the modulation of sensory informations and the autonomic system as neurotransmitters or neuromodulators, both.

Animals↗

PubMed2000

Centrally administered orexin/hypocretin activates HPA axis in rats.

The effects of i.c.v. administration of orexin/hypocretin on plasma ACTH, corticosterone and c-fos mRNA in the paraventricular nucleus (PVN) of the rat were examined. Plasma ACTH levels were markedly increased at 30 min after i.c.v. administration of orexin-A. Plasma corticosterone levels were significantly increased in a dose-related manner 30 min after i.c.v. administration of orexin-A and orexin-B. In situ hybridization histochemistry revealed that the induction of the c-fos mRNA in the parvocellular division of the PVN was increased in a dose-related manner 30 min after i.c.v. administration of orexin-A and orexin-B. These results suggest that central orexin/hypocretin activates hypothalamo-pituitary-adrenal (HPA) axis and may be involved in stress-induced activation of the HPA axis.

Adrenocorticotropic Hormone↗