Biomedical subjects

S Maeda

Publications and source records attributed to S Maeda.

At least 289 records · Page 16Linked to original sources

PubMed1998

Prolonged exercise causes an increase in endothelin-1 production in the heart in rats.

Cardiac myocytes produce endothelin-1 (ET-1). ET-1 has potent positive inotropic and chronotropic effects. We investigated whether production of ET-1 in the heart is altered by prolonged exercise in rats. Rats ran on a treadmill for 45 min. Immediately after this exercise the heart and lungs were quickly removed. Control rats remained at rest during this 45-min period. Expression of preproET-1 mRNA in the heart was markedly higher in the exercised than in the control rats. The peptide level of ET-1 in the heart was also markedly higher in the exercised rats. Expression of endothelin type A- and type B-receptor mRNA and endothelin-converting enzyme mRNA in the heart did not differ between the groups. The peptide level of ET-1 and the preproET-1 mRNA level in the lungs of the exercised rats did not differ from those in the control rats. The present results show that production of ET-1 is markedly increased tissue specifically in the heart by exercise without appreciable changes in endothelin-converting enzyme and endothelin receptor expression. The present study suggests that myocardial ET-1 may participate in modulation of cardiac function during exercise.

Animals↗

PubMed1998

Exercise causes tissue-specific enhancement of endothelin-1 mRNA expression in internal organs.

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide, which also potentiates contractions to norepinephrine in human internal mammary and coronary vessels. Exercise causes a redistribution of blood flow, i.e., the increase in working muscles that is partly attributable to a decrease in visceral blood flow. We hypothesized that exercise causes a tissue-specific increase in ET-1 expression in internal organs. We studied whether exercise affects expression of preproET-1 mRNA in the kidneys and lungs. The rats performed treadmill running (0% grade) for 45 min at a speed of 25 m/min. The plasma concentrations of ET-1, epinephrine, and norepinephrine were greater in the exercise rats than in the sedentary control rats. The expression of preproET-1 mRNA in the kidneys was markedly higher in the exercise rats than in the sedentary control rats, whereas that in the lungs did not differ between the two groups. Therefore, the present study provides a possibility that the exercise-induced increase in production of ET-1 in the kidneys causes vasoconstriction and hence decreases blood flow in the kidneys through its direct vasoconstrictive action and/or its indirect effect of enhancing vasoconstrictions to norepinephrine.

Animals↗

PubMed1998

Apo A-I and apo E concentrations in cerebrospinal fluids of patients with acute meningitis.

It has been demonstrated that apolipoproteins found in cerebrospinal fluid (CSF) play an important role in lipid metabolism in the central nervous system (CNS). Previously we reported that CSF apo A-I levels increased with the severity of neurological damage in poliovirus-infected macaques. In the present study, apo A-I was quantitatively analysed in CSF from patients with or without neurological diseases. In controls, CSF apo A-I level was significantly higher in males; 3.83 (0.40) mg/L, mean (SEM) (n = 19) compared with females, 2.42 (0.26) mg/L (n = 23, P < 0.05). CSF apo A-I concentrations in patients with acute meningitis increased at the active stage, 7.74 (1.78) mg/L (n = 10), but returned to basal concentrations at the convalescent stage 2.72 (0.38) mg/L (n = 10), while the CSF apo A-I level in patients with other neurological diseases remained in the same range as in controls. By contrast, CSF apo E was consistently elevated at either stage of acute meningitis. Furthermore, it was found that the levels of CSF apo A-I, but not of apo E, correlated positively with CSF albumin concentrations. These findings suggest that the CSF apo A-I and apo E have different origins and may play different roles in the lipoprotein metabolism in CNS.

Acute Disease↗

PubMed1998

Characterization of cytoplasmic dynein light-intermediate chain isoforms in rat testis.

We obtained three kinds of novel cytoplasmic dynein light-intermediate chain (LIC) isoforms from rat testis and brain by reverse transcription polymerase chain reaction (RT-PCR). The primers for RT-PCR were designed according to LIC-2 (LIC 53/55) (15). In one novel isoform, the 42 bp specific sequence named TDL was inserted between 1,106 and 1,107 nucleotides (nts) of LIC-2, whereas the 57 bp sequence corresponding to LIC-2 1,339-1,395 nts (BDL) was absent. The TDL and BDL regions were specifically digested with restriction enzymatic treatment and followed by subcloning of non-digested cDNA band in testis and brain, producing an isoform without TDL and BDL regions. BDL specific RT-PCR of testis cDNA followed by sequencing produced an isoform with two specific regions. By Northern blot hybridization using TDL and BDL specific antisense oligo DNA probe, 4.4, 3.5, and 2.0 kb of signals were detected. With both TDL and BDL probes, the 2.0 kb signal was intensely detected in testis, while the 4.4 kb was defected in brain. This indicates that TDL and BDL are derived from the same size of mRNAs. In situ hybridization method using these probes showed that all seminiferous epithelial cells, especially late pachytene spermatocytes, were positive, indicating that LIC 53/55 isoforms were coexpressed in these cells. These findings indicate that LIC 53/55 isoforms provide a variety of dynein subunits, and thus may regulate the dynein-dependent intracellular transport system.

Alternative Splicing↗

PubMed1998

Localization of cytoplasmic dynein light-intermediate chain mRNA in the rat testis using in situ hybridization.

Expression of cytoplasmic dynein light-intermediate chain mRNA in the rat testis was examined using in situ hybridization. The ribonucleotide probe, referred to the 5' end of open reading frame (6-515 nucleotids) of cytoplasmic dynein light-intermediate chain 53/55 (LIC-2) of the rat brain (Hughes et al., 1995. J. Cell Sci., 108: 17-24), was used. All spermatogenic cells were positive. Pachytene spermatocytes in later stages (after-stage VII) were the most intensely positive and round spermatids were also intense. These findings indicated that all spermatogenic cells may store the light-intermediate chain signal, and spermatocytes may produce it during later stages. The reaction in Sertoli cells was constant in intensity during the spermatogenic cycle, indicating that the light-intermediate chain mRNA signal may have no relation to the stage-dependent organelle transport, and that there may be post-translational regulation of the light-intermediate chain. In interstitium, only a few positive cells were observed. Northern blot hybridization demonstrated that one major band (2.0 kb) and two minor bands (4.4 kb and 3.5 kb) were detected in the testis, while one major band (4.4 kb) and one minor band (3.5 kb) were in the brain. This indicated that there are at least 3 isoforms in cytoplasmic dynein light-intermediate chain 53/55.

Animals↗

PubMed1998

[The change of localization on cytokeratin of uterine cervix and the relationship to the pattern of invasion in cervical cancer].

An immunohistochemical study of 63 cases of uterine cervical cancer was undertaken. It was confirmed that the biological character of the cancer cells derived from the reserve cells changed over the course of invasion. Squamous cell carcinoma had positive keratin antibodies such as CK 10/13 (DE-K 13), CK 14 (NCL-LL 002) and CK 7 (OV-TL 12/30). In invasive squamous cell carcinoma, CK 14 positive cells were piled up and tended to be stained positive by PCNA and laminin. There were two types of staining, one of which revealed CK 14 strongly positive, and the other weakly positive. The first type differed from the second in depth and localization. The cells on the margin of a cluster of cancer cells were stained positive with CK 14 as in normal basal cells. The results obtained suggested: 1) squamous cell carcinoma has not only the character of normal squamous cells, but also that of the cells derived from the cervical glands. 2) cancer cells may develop in accordance with the character of basal cells, and the patterns of invasion change according to the character of basal cells in cancer tissue.

Biomarkers, Tumor↗

PubMed1998

Rapid diagnosis at the outpatient clinic for breast tumors by fine needle aspiration cytology. The utility.

The aim of this study was to emphasize the utility and prove the accuracy of rapid diagnosis at the outpatient clinic for breast tumors by fine needle aspiration cytology [FNAC]. Rapid diagnosis for breast tumors by FNAC is performed on the same day just after mammography and echonography are carried out at our hospital and the result reported to the patients while they are waiting at the outpatient clinic. We evaluated FNAC by rapid diagnosis at the outpatient clinic for 1,786 breast tumors during the last ten years. The cases of no judgement (Class 0) were 11%, negative cases (Class I & II) 72%, suspicious cases (Class III) 7%, and positive cases (Class IV & V) 10%. We experienced only 4 false negative cases and 0 false positive cases among 1,198 cases during the last 5 years, whereas there were 8 false negative cases and 2 false positive cases among 588 cases during the first 5 years. Two false positive cases in the the first 5 years were judged as Class IV, but definitive surgery [mastectomy] was not performed because rapid diagnosis during the operation by frozen section confirmed no malignancy. As a result, all the cases in which mastectomies were performed up to now were confirmed malignant. We emphasize that rapid diagnosis at the outpatient clinic for breast tumors by FNAC is very useful for early detection and treatment and it is very important to consider the histological type of breast tumors by FNAC to prevent misjudgement.

Adult↗

PubMed1998

Cloning and expression of mitochondrial capsule selenoprotein gene in the golden hamster.

Mitochondrial capsule selenoprotein (MCS) has been known as a structural protein of the mitochondrial sheath in spermatoza. In the present study, a full-length cDNA encoding the MCS was first isolated from the testes of 10-week-old golden hamsters using a RACE (rapid amplification of cDNA ends) technique and its mRNA expression pattern was investigated from the hamster tissues by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Hamster MCS cDNA was 820 bp long, including 24 bp of the 5'-untranslated region (UTR) and 243 bp of the 3'-UTR, and showed identity of 75.6% and 73.9% with mouse and rat MCS. According to the deduced amino acid (aa) sequence analysis, hamster MCS encoded a polypeptide of 184 aa, including a cysteine- and proline-rich domain which is the characteristic sequences of MCS, and contained 2 in-frame UGA codons for selenocysteine. Hamster MCS also shared aa identity of 64.4% with mouse MCS and contained an Arg-Lys-Ser-Thr-rich region in the N-terminus similar to the mitochondrial targeting signal. On the other hand, according to the RT-PCR analysis using the specific primers for hamster MCS, hamster MCS mRNA was expressed in various tissues as well as the testes. This finding indicates that MCS in hamster may have more than just a function of mitochondrial sheath formation of spermatozoa.

Amino Acid Sequence↗

PubMed1998

Expression pattern of mitochondrial capsule selenoprotein mRNA in the hamster testis.

Mitochondrial capsule selenoprotein (MCS) has been known as a structural protein of the mitochondrial sheath in spermatozoa. In the present study, to determine the expression pattern of MCS mRNA in the hamster testis, northern blot and in situ hybridization analyses using digoxigenin-labeled riboprobes for the hamster MCS were performed in the testes of 10-week-old golden hamsters. According to the northern blot analysis, hamster MCS was detected as a single transcript of about 1 kb in the testis. During spermatogenesis, the hamster MCS mRNA first appeared in step 6 spermatids, gradually increased in round spermatids during spermiogenesis, reached a peak in step 8 spermatids, and persisted a high level until step 13 spermatids. After step 14, the signal began to show a progressive decline in the spermatids and was weakly detected in the tails of step 17 spermatids. However, the signal was not observed in spermatogonia, spermatocytes, Sertoli cells, peritubular myoid cells, and interstitial cells. These findings indicate that hamster MCS is mainly related to the spermiogenesis during spermatogenesis.

Animals↗

PubMed1998

Monoclonal antibody TSd-1 is specific to elongating and matured spermatids in testis of common tree shrew (Tupaia glis).

The monoclonal antibody (MAb), named TSd-1, specific to spermatogenic cells of the common tree shrew (Tupaia glis) was established and characterized using immunohistochemistry and immunoblotting. MAb TSd-1 reacted with elongating and matured spermatids in a stage-dependent manner. TSd-1 recognized a 94 kilodalton (kDa) peptide in the plasma membrane and cytosol. Additionally, an extremely weak 107 kDa band was detected only in the cytosol. The reactions were not detected in round spermatids. In elongating Stage VI spermatids, the plasma membrane and the granular structure within the cytoplasm were intensely positive, and most intense after the appearance of new round spermatids in the lower layer (Stage I). The reactions were observed neither in the other organs of the common tree shrew nor in the testes of other animals, indicating that TSd-1 antigen is specific to the spermatogenic cells of the common tree shrew, and may act on elongating or matured spermatids.

Animals↗

PubMed1998

Geographical variation of mandible size and shape in the Ryukyu wild pig (Sus scrofa riukiuanus).

We measured adult mandibles of Ryukyu wild pigs from Amami-Oshima, Kakeroma, Okinawa, Ishigaki and Iriomote Islands. The size cline was not statistically recognized among the populations of Nansei Islands. The Ishigaki population was significantly larger than Iriomote one in mandible length. Some measurement ratios indicated that the ramus is enlarged laterally and that the body of mandible is dorso-ventrally developed in Ishigaki and Iriomote populations. The Amami-Oshima mandibles were relatively smaller than those of Okinawa and Iriomote populations in length item of body of mandible. These results will contribute to the zoo-archaeology on the historical change of size and shape in the island populations, and to the evolutionary biology on the morphological adaptation of this animal.

Animals↗

PubMed1998

Glucocorticoids possess calcitonin-like antihypercalcemic properties in rats.

The interaction among parathyroid hormone (PTH), calcitonin (CT), and glucocorticoids on blood calcium (Ca) was examined. Prior studies had shown that adrenalectomy (ADX) reduced the fall in blood calcium in rats after parathyroidectomy (PTX). Convincing evidence was provided showing that the ADX effect in PTX rats was due to the loss of corticosterone, the major glucocorticoid in rats; restoring physiological blood levels of corticosterone abolished the ADX effect in PTX rats. The initial attempt of the present study was to explain the failure of ADX or exogenous glucocorticoids to alter serum Ca levels in rats with intact thyroid and parathyroid glands or in thyroidectomized rats with functional parathyroid transplants (PTT). We found, as previously reported, that the 5-h level of serum Ca in rats with parathyroid glands was not affected by s.c. hydrocortisone (cortisol) or by ADX. It was also not affected by thyroparathyroidectomy (TPTX) or after both ADX and TPTX in rats with PTT. These results suggested to us that the glucocorticoid effect to lower serum was inhibited by endogenous parathyroid hormone (PTH) from the parathyroid gland and/or by normal levels of blood Ca. Both of these proposed mechanisms were examined and failed to explain the absence of the ADX effect as well as the glucocorticoid effect in normocalcemic parathyroid-intact rats, because an ADX effect was observed in TPTX rats given hypercalcemic doses of rat or bovine PTH 1-34 or calcitriol. Also, administered cortisol restricted the increased hypercalcemia induced by PTH in ADX-TPTX rats. Expanding on the results in TPTX rats with induced hypercalcemia, we found that neither the ADX effect nor the glucocorticoid effect occurred in thyroid-intact rats with or without functional PTT. These as well as previous results show that: 1. Glucocorticoids, like CT, restrict hypercalcemia in TPTX rats. 2. The ADX effect and its reversal by glucocorticoids in rats with induced hypercalcemia occur only in the absence of the thyroid gland (removal of CT). 3. Glucocorticoids, like CT, lower serum calcium during the hypocalcemia after PTX, an effect that occurs in the presence or absence of the thyroid gland. This study did not reveal why neither ADX nor exogenous glucocorticoids altered serum calcium levels in normocalcemic rats with either intact parathyroid glands or PTT. We conclude that under appropriate conditions, glucocorticoids act in a fashion similar to that of CT in restricting hypercalcemia and in lowering blood Ca.

Adrenalectomy↗

PubMed1998

The N-terminal portion of parathyroid hormone-related protein mediates the inhibition of apical Na+/H+ exchange in opossum kidney cells.

Parathyroid hormone (PTH) and PTH-related protein (PTHrP) can activate a common receptor in several different cell types. Both PTH and N-terminal PTHrP peptides have been shown to acutely inhibit the apical Na+/H+ exchanger in the renal proximal tubule. In this study, the ability of various PTHrP fragments to inhibit apical Na+/H+ exchange was investigated. In addition, the signal transduction events associated with PTHrP inhibition of apical Na+/H+ exchange in polarized OK-P cells were characterized. Both PTHrP-(1-34)NH2 and recombinant full-length PTHrP-(1-141) inhibited apical Na+/H+ exchange activity by approximately 50%. These changes occurred in close temporal association with significant (threefold) increases in cellular cAMP accumulation. PTHrP-(1-34)NH2 had no effect on intracellular Ca2+, inositol phosphate production, or protein kinase C activity. PTHrP peptides, including PTHrP-(38-64)NH2, PTHrP-(67-86)NH2, PTHrP-(102-107)NH2, and PTHrP-(107-139)NH2, which lack the PTH-like N terminus, had no effect on the antiporter activity or cAMP accumulation. The results demonstrate that the N-terminal portion of the PTHrP molecule is responsible for inhibition of the apical Na+/H+ antiporter in OK-P cells.

Animals↗

PubMed1998

Fatal liver cirrhosis and esophageal variceal hemorrhage in a patient with type IIIa glycogen storage disease.

A 45-year-old woman with type IIIa glycogen storage disease (GSD IIIa) died of variceal hemorrhage secondary to liver cirrhosis. The postmortem examination disclosed increased intracellular glycogen in the liver as well as in the heart and skeletal muscle. Although most liver injuries in GSD IIIa have been considered to be non-progressive in adulthood, liver cirrhosis can be a cause of death in some patients.

Diagnosis, Differential↗

PubMed1998

Intraosseous meningioma with a dural defect.

A 56-year-old female presented with a rare intraosseous meningioma associated with an unusual dural defect caused by invasion of the tumor. The underlying dura mater is normal or thickened in most cases of intraosseous meningiomas. Most intraosseous meningiomas are benign histologically, but they should be extirpated before invasion into the subdural space occurs.

Dura Mater↗

PubMed1998

Experimental studies of subjective response to road traffic-induced building vibration.

The road traffic-induced building vibration was recorded continuously for 24 hr in three orthogonal axes outside and inside the building. Several alternative objective methods of quantifying the severity of exposures to whole-body road traffic-induced building vibration are used. The relationship between the results of all objective evaluation methods of vibration-induced by road traffic and the subjective responses to building vibration are compared. It was conducted that the ISO 2631-2 z-axis frequency weighting combined with a measure of vibration dose value (VDV = [integral of a4(t) dt)]1/4 may use a practicable objective evaluation procedure in buildings than L10 percentile vibration levels. It was also cleared that the L10 percentile vibration levels at the ground boundary of the regulation law of Japan Environmental Agency must be low levels.

Building Codes↗

PubMed1998

Whole-body vibration and health effects in the agricultural machinery drivers.

Recently farm mechanization has been widespread and developing rapidly, in particular riding farm machines are increasingly used in paddy fields in Japan. We have no information available on the actual situation regarding whole-body vibration on the seats of these farm machines from the standpoint of labour protection. Measurement and evaluation of whole-body vibration was performed on the seats of popular riding agricultural machineries. Whole-body vibration on the seats of combine harvesters and wheel tractors exceeded exposure limits and the fatigue-decreased proficiency boundary limit of 8 hr and also shortened the reduced comfort boundary limits of ISO 2631 (1985). Some combines, tractors and carieers had only less than one hour exposure duration as compared with the ISO 2631-1 standard (1997). On the other hand a questionnaire was also performed on the subject of agricultural machine operators. Any specific injury or other effects, i.e. low back injuries were not found among the group of operators as compared with those in non-operator farmers. It seems to be difficult to find out the health effects of whole-body vibration itself, because there may be a lot of causes, i.e. working posture, operating heavy materials, in farm working conditions.

Adult↗

PubMed1998

Measurement of hand-transmitted vibration of tapping the long cane for visually handicapped people in Japan.

The long cane can be used as a mobility aid for visually handicapped people. According to a questionnaire completed by Japanese cane users, it seems they are not always satisfied with using long canes for a variety of reasons. In this study, hand-transmitted vibration from the long cane due to tapping the ground was measured because an exposure to repeated shock-type tapping vibration may affect the hand-arm system. A sighted female wearing a blindfold participated. The measurement was carried out in different conditions with three different ground materials both indoor and outdoors. The vibration at three axes of the cane grip and one axis at the wrist were measured. The pinch forces between an index finger and the grip were also measured using a strain gauge in order to observe how the vibration characteristics depend on the changing forces. Measurement, evaluation and assessment were based on the International Standard (ISO 5349). The estimated daily exposure time and the transmissibility were obtained in order to investigate the severity of the hand-transmitted vibration caused by the long cane. It was found that the characteristics of tapping vibration depend on different measurement conditions and the vibration might be associated with a health risk over a long life span.

Adult↗