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S Kamiyama

Publications and source records attributed to S Kamiyama.

At least 19 recordsLinked to original sources
PubMed1999

Poor renal accumulation of 99mTc-DMSA in idiopathic tubular proteinuria.

In Japanese patients idiopathic tubular proteinuria presents mainly as asymptomatic tubular low molecular weight proteinuria. This disease has recently been shown to resemble Dent's disease which is characterized by tubular proteinuria, hypercalciuria, rickets and eventual renal failure. We report on 4 children with idiopathic tubular proteinuria. Although they had normal renal function, as evidenced by serum creatinine or creatinine clearance, they had very poor renal accumulation of 99mTc-DMSA and the presence of large amounts of tracer in the bladder. Additionally, the patient with the largest amounts of tubular proteinuria had the poorest renal accumulation of the 4 patients. The renal accumulation of tracer decreased with time from a maximum at 10 min after injection. These findings demonstrate that the tracer, once taken to be confined to the proximal tubular cells, is immediately excreted to the tubular lumen. We suggest that poor renal accumulation of 99mTc-DMSA is very important in elucidating the mechanism of idiopathic tubular proteinuria, and that 99mTc-DMSA renoscintigraphy is useful in the evaluation of the patient's renal function over time.

Adolescent↗
PubMed1998

Inhibitory effects of lipid oxidation on the activity of plasma lecithin-cholesterol acyltransferase.

We investigated the effects of free radical generation on the esterification of cholesterol by lecithin-cholesterol acyltransferase (LCAT). A water-soluble free radical initiator, 2,2'-azobis-amidinopropane dihydrochloride (AAPH), inhibited the activity of plasma LCAT as a function of the incubation time after its addition. When a small amount of oxidized HDL was added to plasma, LCAT activity was dose-dependently inhibited. To identify the effects of HDL oxidation on LCAT activity, a purified enzyme and cofactor in a vesicle solution (an artificial substrate) were used. i) LCAT activity was inhibited by the oxidation of substrate vesicles, this inhibition being related to the degree of oxidation. ii) This inhibition was observed even if apolipoprotein A-I was not oxidized. iii) Oxidized phosphatidylcholine, but not oxidized cholesterol, in the vesicles affected LCAT activity. iv) The addition of 0-40% of oxidized vesicles to normal substrate vesicles resulted in the activity of LCAT being inhibited in a dose-dependent manner. These results suggest that the esterification of cholesterol by LCAT may be affected by the oxidation of substrate phosphatidylcholine via free radical generation in the plasma.

Cholesterol↗
PubMed1998

Urinary output changes in racemic ethylamphetamine and optical activity discrimination in rat urine by HPLC analysis.

Characterization of optical activity and simultaneous analysis of racemic ethylamphetamine (EAMP) and its metabolites, as well as the urinary excretion of the optical isomers, were examined in rats by high-performance liquid chromatography (HPLC). Analysis of the optical isomers of EAMP, amphetamine (AMP), para-hydroxy-ethylamphetamine (p-OH-EAMP), and para-hydroxy-amphetamine (p-OH-AMP) was performed within 90 min. The limit of detection was 30 ng for EAMP and AMP, and 60 ng for p-OH-EAMP and p-OH-AMP per 20 microliters injection. After oral administration of racemic EAMP, rat urine specimens were collected at four intervals, 0-4, 4-12, 12-20 and 20-24 h. After administration of 30 mg/kg EAMP, not only each isomer of EAMP, i.e. AMP, p-OH-EAMP and p-OH-AMP, but also an unidentified substance (UI) were detected. The UI was presumed to be 3-hydroxy-4-methoxy-N-EAMP or 3-methoxy-4-hydroxy-N-EAMP by gas chromatographic mass spectrometry (GC-MS) analysis. The d-isomer of EAMP was generally excreted more abundantly than the l-isomer (p < 0.01-0.05). The d-isomer of AMP and p-OH-EAMP was excreted in the first 4 h in a somewhat smaller amount than the l-isomer but thereafter in a greater amount than the l-isomer. The d-isomer of p-OH-AMP was generally excreted in a smaller amount than the l-isomer (p < 0.1-0.05). The total percentages of the dose excreted up to 24 h were 2.65% of the dose of EAMP administered [d: 2.04% and l: 0.61%], AMP 3.15% [d: 1.68% and l: 1.47%], p-OH-EAMP 63.06% [d: 32.68% and l: 30.38%], and p-OH-AMP 2.57% [d: 1.05% and l: 1.52%]. The optical purity ratio (l/d) of EAMP up to 24 h was 0.31, significantly lower than that (1.03) of the original racemic EAMP (p < 0.01). The changes in the excretion of EAMP and AMP indicated a stereoselective disposition, but those of p-OH-EAMP and p-OH-AMP were unremarkable: the d- and the l-isomer of p-OH-EAMP and p-OH-AMP did not differ significantly. The entire amount excreted up to 24 h was about 71.43% of the dose administered; the d-isomer 37.45% and the l-isomer 33.98%. The l/d was 0.91, which was clearly less than that of the original racemic EAMP (p < 0.01). These results suggested stereoselective disposition of EAMP in the rat, and the methods are potentially applicable to identification of the optical activity of EAMP and thereby of methamphetamine abusers.

Amphetamine↗
PubMed1997

Evaluation of five polymorphic microsatellite markers for typing DNA from decomposed human tissues--correlation between the size of the alleles and that of the template DNA.

For PCR-based genotyping using polymorphic microsatellite markers, DNA from decomposed postmortem human tissues was fractionated into six groups according to molecular size. The minimum required amounts of this degraded DNA, for detecting alleles at five microsatellite loci (ACTBP2, CMAG, HUMTH01, CYP19, and LPL) and one minisatellite locus (MCT118) were investigated respectively. The allele patterns were detected by electrophoresis of the PCR products on a 6%-denaturing polyacrylamide gel following silver staining. The detection of alleles for the loci with large allele size required more template DNA with higher molecular size than for that with small allele size. Amounts from 0.3 ng to 5 ng were needed for allele detection on genomic DNA from fresh blood. When the decomposed DNA mixture was used as the template, approximately ten times the amount of genomic DNA was required to detect alleles at the three loci of LPL, CYP19 and HUMTH01, while 24 to 67 times was required for the loci, CMAG, ACTBP2 and MCT118. It was demonstrated that a minimum molecular, size and amount of template DNA was needed for amplifying alleles of the six loci, and degraded DNA less than minimum size in the samples would prevent the detection of the loci which have large allele size.

Alleles↗
PubMed1997

Role of the C-termini of human and chicken plasma retinol-binding proteins.

The most prominent differences between mammalian and non-mammalian vertebrate retinol-binding proteins (RBP) are in the C-terminal sequences. We have cloned and sequenced the cDNA for chicken RBP. Transfected COS cells that transiently expressed mammalian (human) or non-mammalian (chicken) RBP were used to demonstrate that both proteins were able to bind retinol and human transthyretin. However, we observed an increased retinol-independent secretion in cells expressing chicken RBP and reduced ligand-dependent secretion compared to the human protein. It can therefore be concluded that the C-terminal amino acid tail which is missing in chicken RBP compared to human RBP might play a role in retention and ligand-induced secretion.

Amino Acid Sequence↗
PubMed1996

Allele detection and population study in Japanese using two STR loci (CYP19 and HUMTH01).

Allele fragments at two polymorphic short tandem repeat (STR) loci, CYP19 and HUMTH01, were simultaneously amplified in a sample of 200 unrelated Japanese individuals living in the Kanto area, including Tokyo. After electrophoresis in PAG, the new alleles 7, 10, 11, 12, and 13 were detected at the CYP19 locus in Japanese. HUMTH01 allele frequencies in Japanese differed greatly from those reported for Caucasians and Asians living in the US. The polymorphism information content (PIC) in Japanese was calculated as 0.46 for CYP19 and 0.66 for HUMTH01. The power of discrimination (PD) was 0.7 for CYP19 and 0.86 for HUMTH01, and the combined PD was calculated as 0.96. No significant deviations from Hardy-Weinberg equilibrium could be observed for these systems.

Alleles↗
PubMed1996

Inhibitory effects of oxidized low-density lipoprotein on the activity of plasma lecithin: cholesterol acyltransferase.

Lecithin: cholesterol acyltransferase (LCAT) is an enzyme that is important in the cholesterol reverse-transport system by converting the surface cholesterol of high-density lipoprotein (HDL) to cholesterol ester inside HDL. We have investigated changes in plasma LCAT activity induced by oxidized low-density lipoprotein (ox-LDL). (i) LCAT activity was inhibited by the addition of even a small amount of ox-LDL, (ii) This inhibitory effect was dose-dependent and was related to the degree of oxidation of LDL, (iii) As this inhibitory effect was not prevented by antioxidants, it is suggested that it does not occur via oxidation of substrate HDL. These results suggest that cholesterol reverse-transport via HDL may be affected by ox-LDL and they are noteworthy in suggesting a new physiological function for ox-LDL.

Antioxidants↗
PubMed1993

Retroviral gene expression as a possible biomarker of aging.

We examined effects of aging on endogenous retrovirus gene expression of mouse lymphocytes with a hypothesis that it may be a useful biomarker of aging. Mice have endogenous murine leukemia viruses (MuLVs) in their chromosomes. We detected the gene expression of long terminal repeats (LTRs) of MuLVs. Brains, livers and spleens were taken from young (3 months old) and old (27 months old) male C57BL/6 mice. In addition to these control (C) mice, we also determined gene expression in dietary restricted (DR) mice, in which rates of aging are known to be slowed. RNA was extracted from the tissues and converted into cDNA. The MuLV-LTR portion of cDNA was amplified by polymerase chain reaction (PCR). The PCR products were analyzed by agarose gel electrophoresis. Gene expressions of young mice were found to be tissue-specific. Expressed LTRs from brains, livers and spleens were that of 370 base-pairs (bp), those of 370 and 620 bp, and those of 370, 400 and 620 bp, respectively. Old mice of C group, however, decreased tissue specificity: expressed LTRs became those of 370-400 bp in any tissues. In contrast the tissue specific gene expression was conserved in old DR mice which had to get prolonged life span and decreased lymphoma incidence. Thereby, gene expression of endogenous retroviruses appears to change during aging and to be modifiable by life-prolonging DR. It may be therefore used as a biomarker of aging in mice. Humans are known to have similar gene elements like MuLV. The present findings demonstrate a possibility of application of endogenous gene expressions to the epidemiology of aging.

Aging↗
PubMed1993

Energy restriction suppresses microsomal Ca(2+)-ATPase activities in various organs in C57BL/6 female mice in both euthermic and torpor states.

C57BL/6 female mice were fed a daily control diet (n = 5, 3.9 g/day, 95 kcal/week) or ER diet (n = 5, 2.3 g/day, 48 kcal/week) at 1800 h from 6 weeks of age. Telemetry, conducted at 6 months of age, confirmed that all ER mice entered daily torpor (core body temperature less than 31 degrees C) for 6.63 +/- 2.34 h/day while control mice were euthermic (> 35 degrees C). In vitro activities of microsomal Ca(2+)-ATPase were determined in the brain, liver, salivary gland and kidney from these mice at 6 months of age. Assays were performed at three incubation temperatures of 37 degrees C, 31 degrees C and 25 degrees C. In assays at 37 degrees C, the activities of Ca(2+)-ATPase in the brain and salivary gland from ER mice were lower than those in corresponding organs from control mice. The suppression became profound as the incubation temperature decreased. On the other hand, at 37 degrees C Ca(2+)-ATPase activities in the liver and kidney from ER mice were not lower than those in corresponding organs from control mice, but decreased significantly at low temperatures. Microsomal Ca(2+)-ATPase activities thus appeared to be reduced in ER mice, although it remains unknown whether the present results represent reduced in vivo capacities to regulate cytosolic Ca2+ concentrations.

Animals↗
PubMed1993

Effects of energy restriction on age-associated changes of DNA methylation in mouse liver.

DNA methylation is known to change with age in several mammalian species. Here we have examined the effect of dietary energy restriction on this age-associated change in liver DNA of C3H/SHN mice. The total 5-methyldeoxycytidine level in the genome decreased slightly soon after energy restriction started. The effect, however, diminished with time and no appreciable difference was detected at middle and old ages. The degree of methylation at the c-myc gene, on the other hand, was not affected by energy restriction at early periods, but the age-dependent alterations at later ages were repressed. This is a new finding to show that DNA methylation is one of the molecular indices of aging affected by energy restriction. It suggests an importance of DNA methylation in the aging process.

Aging↗
PubMed1993

[Optical isomer analysis of ethylamphetamine from human urine and an anorectic drug, Apetinil Depo].

Two analyzed cases of Ethylamphetamine (EAMP) were reported. By using HPLC with a chiral column, racemic (d, l)-EAMP were detected from the urine of a Japanese male and an anorectic drug, which had been possessed by a Thai club hostess. From the urine of the former, d-MAMP, d-AMP and l-MAP were also detected. EAMP is now categorized to be one of psychotropic drugs in Japan, but not under the strict control of Psychostimulants Law. In near future, because of the similar action to stimulant drugs, EAMP will be apprehensive of the abuse in Japan.

Adult↗
PubMed1993

Energy restriction that inhibits cellular proliferation by torpor can decrease susceptibility to spontaneous and asbestos-induced lung tumors in A/J mice.

BACKGROUND: Energy restriction (ER) inhibits various tumors in mice. A/J mice have a very high incidence of lung tumors, that are correlated with elevated levels of pulmonary cell proliferation in this strain. Using A/J mice, we studied the effects of ER on spontaneous and asbestos-induced lung tumors and on labeling indices in the lung as a proximal marker of susceptibility to lung tumors to obtain better understanding of the mechanism of ER in reducing tumorigenesis. EXPERIMENTAL DESIGN: Experiment 1: A/J female mice were instilled intratracheally with asbestos or titanium dioxide or simple saline at 20 weeks of age. At 21 weeks of age, mice of the ER diet group were switched from the control diet (350 kJ/week) to the ER diet (175 kJ/wk) until sacrifice at 105 weeks of age, whereas mice of the control diet group were continued on the control diet. Experiment 2: A/J female mice were begun on ER or control diets at 6 weeks of age. The control and ER mice were kept at 20 to 22 degrees C, whereas mice of another ER group (ER+I) were kept at 30 degrees C until 24 weeks of age. Body temperatures of these mice were monitored by telemetery. RESULTS: The present ER was shown to suppress the development of both asbestos-induced and spontaneous lung tumors. ER mice were confirmed to become torporfic, whereas control and ER+I mice did not. Labeling indices were reduced by ER in the lung as well as in other organs. The reduction of labeling indices was, however, almost recovered by increasing the housing temperature to 30 degrees C. CONCLUSIONS: ER which reduces cellular proliferation in various organs by torpor was shown to inhibit lung tumors. Inhibition of lung tumors by ER is likely to involve a decrease in cell proliferation.

Animals↗
PubMed1992

Specific inhibition of pituitary prolactin production by energy restriction in C3H/SHN female mice.

Pituitaries were excised from control (C; 95 kcal/week) or energy restricted (ER; 48 kcal/week) female mice of 2, 3, 7, and 18 months of age. The total RNA and relative actin mRNA amounts in the pituitary were significantly greater in C than in ER mice both at 7 and 18 months. Prolactin (PRL) mRNA, standardized with actin mRNA, was significantly less in ER mice of 7 (50%) and 18 (51%) months of age than in age-matched controls, suggestive of specific inhibition of PRL mRNA transcription. Pituitary RNA and actin mRNA increased from 7 to 18 months in C mice but not in ER mice. Similarly, mean pituitary volumes increased between 2 and 18 months in C mice but not in ER mice. PRL mRNA, standardized with actin mRNA, did not change in either C or ER mice 7-18 months of age. All examined C mice of 3, 7, and 18 months of age had estrous cycles but none of the ER mice of the same ages. After 1 month of ER, the pituitary volumes and serum insulin concentrations in 2-month-old female mice were reduced. Thus net reduction of PRL mRNA per pituitary by ER is attributable to decreases in pituitary size and specific inhibition of PRL production, both of which may be due to low estrogen and insulin levels.

Actins↗
PubMed1992

A skin-specific MMTV provirus is stably transmitted by horizontal transmission.

Mouse mammary tumor virus (MMTV) is a retrovirus with a life cycle that remains to be elucidated. In establishing Mtv-4 congenic mice, an extra copy of the MMTV provirus was found specifically in the skin of both sexes of SHN mice but not in C3H/He mice. This extra copy was not, however, found in other normal tissues such as brain, lung, liver, spleen, kidney, uterus, testis, and mammary glands from SHN or C3H/He mice. In the skin of SHN mice, an 11-kb DNA fragment, which approximates in size to the entire MMTV genome, was detected in undigested high-molecular weight DNA. This unique MMTV provirus was shown to be transmitted horizontally from SHN mice to exogenous-MMTV-free C3H/He mice through nursing. The virus is thus concluded to be exogenous. Clusters of MMTV type A particles were found in sebaceous glands by electronmicroscopic examination. The present findings indicates that exogenous MMTV may be stably maintained in the skin as an unintegrated provirus during its life cycle.

Animals↗
PubMed1992

[Identification of optical isomers of methamphetamine and its application to forensic medicine].

In order to identify optical isomers (d and l-) of methamphetamine (MAMP), GC-MS analysis using optically resolvable reagent of N-trifluoroacetyl-L-prolyl chloride (L-TPC) and HPLC analysis using chiral cellulose-based columns were compared. In analysis of d- or l-MAMP (M) of TPC (T) derivatives by the GC-MS, contrary to the expectation that only d(M)-L(T) or l(M)-L(T) could be detected chemically, two diastereomers of d(M)-L(T) and d(M)-D(T) for d-MAMP and two of l(M)-L(T) and l(M)-D(T) for l-MAMP were demonstrated respectively. This results was attributed to a small percentage of D-TPC present in L-TPC. For racemic (dl)-MAMP, none of these four isomers could be individually isolated, and they were detected as two overlapping peaks. In the HPLC analysis using chiral columns, d- and l-isomers of MAMP and amphetamine (AMP) could be clearly isolated with merely one analytical procedure, and the l/d ratio was possible to calculate with facility. From the rats urine administered d- or l-MAMP, only the corresponded optically active form of the administered drug was detected, and when racemic (dl)-MAMP was administered, d-MAMP, l-MAMP and their metabolites AMP were distinctly detected. The l/d ratio calculated from amount of MAMP and AMP excreted in rat urine within 24 hr was not in accordance with that of the administered dl-MAMP (l/d = 1.01): the l/d ratio was 0.45 for MAMP and 0.58 for AMP, and 0.50 for the total of MAMP and AMP. The similar results were observed in case of racemic (dl)-AMP. From several human specimens obtained from the cadavers dead by MAMP poisoning, only d-MAMP and the metabolite d-AMP were detected, and neither l-MAMP or l-AMP were demonstrated. In particular, a high concentration of d-MAMP was detected in gastric contents, brain, lung and liver. From the MAMP powder in possession, only d-MAMP was detected. These results suggest that this chiral column-HPLC procedure could be applied to medicolegal practice and forensic scientific investigation.

Animals↗