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Biomedical subjects

M Kojima

Publications and source records attributed to M Kojima.

At least 163 records · Page 9Linked to original sources
PubMed2000

HNF-4 plays a pivotal role in the liver-specific transcription of the chipmunk HP-25 gene.

The gene for chipmunk hibernation-specific protein HP-25 is expressed specifically in the liver. To understand the transcriptional regulation of HP-25 gene expression, we isolated its genomic clones, and characterized its structural organization and 5' flanking region. The gene spans approximately 7 kb and consists of three exons. The transcription start site, as determined by primer extension analysis, is located at 113 bp upstream of the translation initiation codon. Transient transfection studies in HepG2 cells revealed that the 80 bp 5' flanking sequence was sufficient for the liver-specific promoter activity. In a gel retardation assay using HepG2 nuclear extracts, the 5' flanking sequence from -74 to -46 showed a shifted band. All cDNA clones isolated by a yeast one-hybrid system for a protein capable of binding to this 5' flanking sequence encoded HNF-4. HNF-4 synthesized in vitro bound to this sequence in a gel retardation assay. Furthermore, supershift assays with anti-(HNF-4) Ig confirmed that the protein in HepG2 or chipmunk liver nuclear extracts that bound to this sequence was HNF-4. When transfected into HeLa cells, HNF-4 transactivated transcription from the HP-25 gene promoter, and mutation of the HNF-4 binding site abolished transactivation by HNF-4, indicating that HNF-4 plays an important role in HP-25 gene expression.

Amino Acid Sequence↗
PubMed2000

Pathology of a dissecting intracranial aneurysm.

The pathological findings of six autopsy cases of dissecting intracranial aneurysm are studied. Clinically, all cases exhibited systemic hypertension or left ventricular hypertrophy. Macroscopically, all cases exhibited rupture of the vertebral artery and subarachnoid hemorrhage. Two types of lesion were present. First, all cases showed the formation of a dilatated pseudoaneurysm with widespread disruption of the entire arterial wall, which was composed of thin adventitia. Second, a medial disruption of the arterial wall and subadventitial dissecting hemorrhage, which formed a false lumen and stenosis of the 'true' lumen of the artery, was also found. However, these lesions were found to be connected to the site of rupture. The autopsy cases within 1 day of onset of intracranial dissecting aneurysm showed the formation of fibrin thrombus, a marked degree of leukocyte infiltration and necrosis of the arterial wall at the site of the lesion. The cases that survived more than 1 week showed smooth muscle cell proliferation, macrophage accumulation and lymphocytic infiltration. No arteriosclerosis was found in any lesion studied. These data suggest that the disruption of the entire arterial wall might initially occur and cause medial disruption and subadventitial hemorrhage. Hypertension and arteriosclerosis might function as causal and protective factors in the pathogenesis of dissecting intracranial aneurysms, respectively.

Adult↗
PubMed2000

Reactive follicular hyperplasia in the lymph node lesions from systemic lupus erythematosus patients: a clinicopathological and immunohistological study of 21 cases.

To clarify the clinicopathological and immunohistological findings of reactive follicular hyperplasia in systemic lupus erythematosus (SLE) lymphadenopathy, we examined 21 such cases, including four males and 17 females. Three main patterns could be delineated: pattern A, histological features of Castleman's disease (n = 6); pattern B, follicular hyperplasia with pronounced arborizing vasculature in the paracortex resembling T-zone dysplasia with hyperplastic follicles (n = 6); and pattern C, follicular hyperplasia without any other specific findings (n = 9). The patients who showed patterns A and B on histology were all female with a median age of 36 years, and presented with the lymphadenopathy within 4 months, some before a definitive diagnosis could be made. The group with pattern C included four males and five females with an age ranging from 20 to 58 years (mean, 37 years). In seven of them, the lymphadenopathy was noted 6 months or more after the therapy had been initiated. In a virological study, a small to moderate number of the lymphoid cells were positive for the Epstein-Barr virus-encoded small RNA in five of 10 cases examined. Human herpesvius 8 was not detected in the four cases examined by polymerase chain reaction and immunohistochemistry. The present study demonstrated that SLE lymphadenopathy showed histological variety and occasionally represented histopathological findings of multicentric Castleman's disease or findings similar to T-zone dysplasia with hyperplastic follicles in the biopsied specimens. We emphasize that careful attention to these morphological features, together with clinical and laboratory examinations, should allow a firm diagnosis of SLE to be made, providing information that is pertinent to the treatment of the disease. Moreover, disarray of the follicular dendritic cell (FDC) network, which could be easily detected by immunohistochemistry, was found in approximately 60% of our series. SLE lymphadenopathy should be listed as one of the diseases occasionally associated with disarray of the FDC network, although its clinicopathological significance remains unclear.

Adult↗
PubMed2000

Comparative study of pulsed dye laser and pneumatic lithotripters for transurethral ureterolithotripsy.

BACKGROUND: Clinical effectiveness and safety of the Swiss Lithoclast (Lithoclast) and the Candela MDL-2000 (MDL) in the treatment of lower ureteral stone were examined retrospectively. METHODS: Eighty-six stones from 66 patients and 26 stones from 20 patients were treated by Lithoclast and MDL, respectively. RESULTS: The stone-free rate on 3-month follow-up was 97% and 95% for the Lithoclast and MDL, respectively (no significant difference). The operation time was significantly shorter for the Lithoclast than for the MDL (90.2+/-50.2 vs 120.4+/-55.1 min; P<0.05). Postoperative analgesics were required significantly less frequently in Lithoclast (10/66 vs 11/20; P<0.01). Postoperative hospital stay was significantly shorter for Lithoclast (8.7+/-5.1 vs 12.1+/-4.2 days; P<0.01). CONCLUSIONS: Swiss Lithoclast is an effective and less invasive modality for endoscopic treatment of lower ureteral stones.

Adult↗
PubMed2000

Transrectal power Doppler imaging in the detection of prostate cancer.

OBJECTIVES: To evaluate the clinical utility of transrectal power Doppler imaging (PDI) of the prostate for detecting prostate cancer in patients with abnormally high serum levels of prostate specific antigen (PSA). PATIENTS AND METHODS: Patients (107) with abnormally high serum PSA levels were assessed using a digital rectal examination (DRE), transrectal ultrasonography (TRUS) and PDI. Any hypervascular lesion on PDI was graded on a scale of 0-3, where grade 1-3 was considered positive and grade 0 negative. Patients were then diagnosed by prostatic needle biopsy and the results compared with the other detection methods. RESULTS: Needle biopsy confirmed prostate cancer in 41 (24%) of the 170 patients. PDI was positive in 68, of whom 40 (59%) had prostate cancer; all those but one having prostate cancer were positive on PDI. Thus, PDI had a high sensitivity of 98% (40/41) and a negative predictive value of 99% (101/102). PDI could have saved a significant number of patients from undergoing unnecessary biopsies, compared with DRE and TRUS (P < 0.001). CONCLUSION: The use of PDI in detecting prostate cancer might reduce the number of unnecessary needle biopsies of the prostate in patients with abnormally high serum PSA levels.

Aged↗
PubMed2000

Rapid turnover of tryptophan hydroxylase is driven by proteasomes in RBL2H3 cells, a serotonin producing mast cell line.

Previously we demonstrated that tryptophan hydroxylase (TPH) undergoes very fast turnover driven by ATP-dependent proteolysis in serotonin producing mast cells [Hasegawa et al. (1995) FEBS Lett. 368, 151-154]. We searched for the major proteases involved in the rapid degradation of TPH in RBL2H3 cells. Among various protease inhibitors tested, proteasome inhibitors MG115, MG101, MG132, and lactacystin effectively inhibited the intracellular degradation of TPH. Administration of the proteasome inhibitors to cultured cells caused more than a 5-fold accumulation of TPH. Administration of the inhibitors together with cycloheximide stabilized the amount of TPH with no appreciable increase or decrease. Although MG-series proteasome inhibitors could inhibit calpain, the involvement of calpain was excluded since the cysteine protease inhibitor E-64-d, which acts on calpain, had no effect. Extracts of RBL2H3 cells were shown to contain a protease that digests TPH in an ATP-dependent manner and is sensitive to proteasome inhibitors. The ubiquitination of TPH could be visualized by Western blot analysis using both anti-TPH and anti-ubiquitin antibodies. Based on these results, we conclude that 26S proteasomes are mainly involved in the degradation of TPH. In the reported amino acid sequences of TPH from various sources including human, rabbit, rat, and mouse, a PEST sequence that is widely shared among short-lived proteins has been recognized. It was noted that the PEST sequence lies within the most conserved portion of the enzyme, the pteridine binding site.

Amino Acid Motifs↗
PubMed2000

Structure of the pig sterol 14alpha-demethylase (CYP51) gene and its expression in the testis and other tissues.

A cDNA coding sterol 14alpha-demethylase (CYP51), which was isolated from a pig liver cDNA, contained a 1,512 bp open reading frame and a 758 bp 3'-untranslated region. The deduced amino acid sequence was 94% identical to those of human and rat CYP51s. The pig CYP51 gene spanned about 21 kb and was divided into 10 exons. The sites of exon-intron junctions were completely identical to those in the human and rat CYP51 genes. Five GC boxes, but not a TATA box, were found in the 5'-flanking region of the gene, and cyclic AMP and sterol responsive elements were also found in this region. The main transcription start site determined with the 5'-RACE method with poly(A)(+) RNA from the liver and testis was located at 143 nucleotides upstream from the initiation codon in both tissues. Northern blot analysis revealed that an approximately 2.4 kb mRNA, which is produced through the use of a polyadenylation signal (AATAAA) located at 740 nucleotides downstream of the stop codon, was expressed in all the tissues examined in pigs: The mRNA levels were much higher in the liver and testis than in the kidney, lung, and epididymis. Furthermore, after the onset of spermatogenesis, a smaller size of mRNA (about 1.8 kb) was found in the testis but not in the epididymis. The 1.8 kb mRNA was produced through the use of an unusual polyadenylation signal (AAGAAA) located at 28 nucleotides downstream of the stop codon.

3' Untranslated Regions↗
PubMed2000

Identification of the cleavage sites of oxidized protein that are susceptible to oxidized protein hydrolase (OPH) in the primary and tertiary structures of the protein.

Amino acid sequences in H(2)O(2)-oxidized bovine serum albumin (BSA) that are susceptible to proteolytic cleavage by oxidized protein hydrolase (OPH) were investigated. When oxidized BSA was treated with OPH, low-molecular-weight fragments (54, 46, 24, 22, 20, and 8 kDa) were produced as analyzed by SDS-PAGE. N-Terminal amino acid sequence analysis of these fragments indicated that oxidized BSA was cleaved by OPH at three major sites, Leu218-Ser219, Tyr410-Thr411, and Phe506-Thr507, at an early stage of the proteolytic degradation. In the three-dimensional structure of BSA deduced by computer modeling, these cleavage sites were found to be located slightly inside the BSA molecule, in positions not easily accessible by OPH. The influence of oxidation on the tertiary structure of BSA was then investigated by hypothetically replacing all the four methionine and two tryptophan residues with their oxidized forms, methionine sulfoxide and N'-formyl-kynurenine, respectively. The three-dimensional structure of the hypothetically oxidized BSA indicated that all the three cleavage sites in the protein could become more exposed to the solvent than in unoxidized BSA. These results suggest that, upon oxidation of BSA, the amino acid sequences that are potentially cleavable by OPH but present inside the molecule become exposed on the surface and susceptible to proteolysis by OPH. This is the first report demonstrating the cleavage sites of oxidized protein by oxidized protein-selective protease, suggesting the possible mechanism of oxidized protein-selective degradation by the enzyme.

Amino Acid Sequence↗
PubMed2000

Circadian waves of expression of the APRR1/TOC1 family of pseudo-response regulators in Arabidopsis thaliana: insight into the plant circadian clock.

The Arabidopsis pseudo-response regulator, APRR1, has a unique structural design containing a pseudo-receiver domain and a C-terminal CONSTANS motif. This protein was originally characterized as a presumed component of the His-to-Asp phosphorelay systems in Arabidopsis thaliana. Recently, it was reported that APRR1 is identical to the TOC1 gene product, a mutational lesion of which affects the periods of many circadian rhythms in Arabidopsis plants. TOC1 is believed to be a component of the presumed circadian clock (or central oscillator). Based on these facts, in this study four more genes, each encoding a member of the APRR1/TOC1 family of pseudo-response regulators were identified and characterized with special reference to circadian rhythms. It was found that all these members of the APRR1/TOC1 family (APRR1, APRR3, APRR5, APRR7, and APRR9) are subjected to a circadian rhythm at the level of transcription. Furthermore, in a given 24 h period, the APRR-mRNAs started accumulating sequentially after dawn with 2-3 h intervals in the order of APRR9-->APRR7-->APRR5-->APRR3-->APRR1. These sequential events of transcription, termed 'circadian waves of APRR1/TOCI', were not significantly affected by the photoperiod conditions, if any (e.g. both long and short days), and the expression of APRR9 was first boosted always after dawn. Among these APRRs, in fact, only the expression of APRR9 was rapidly and transiently induced also by white light, whereas such light responses of others were very dull, if any. These results collectively support the view that these members of the APRR1/TOC1 family are together all involved in an as yet unknown mechanism underlying the Arabidopsis circadian clock. Here we propose that the circadian waves of the APRR1/TOC1 family members are most likely a molecular basis of such a biological clock in higher plants.

Amino Acid Sequence↗
PubMed2000

Doppler resistive index in benign prostatic hyperplasia: correlation with ultrasonic appearance of the prostate and infravesical obstruction.

OBJECTIVE: This study was designed to characterize the resistive index (RI) of prostatic blood flows obtained by transrectal power Doppler sonography (TRPDS) in benign prostatic hyperplasia (BPH). METHOD: In 140 patients with lower urinary tract symptoms, the RI was measured using TRPDS and compared with age and planimetric parameters of the prostate obtained by conventional transrectal sonography. In addition, the RI was related with pressure flow studies. RESULTS: The RI was significantly higher in patients with BPH (0.72+/-0.06, p<0.0001) than those with a normal prostate (0. 64+/-0.04). Although the RI correlated significantly with age and all prostatic planimetric parameters, multiple regression analysis revealed that age and presumed circle area ratio were independent predictors for RI. The RI was also higher in patients with infravesical obstruction than those without (0.74+/-0.06 vs. 0. 70+/-0.05, p<0.005). There was a significant correlation between RI and urodynamic parameters obtained in pressure flow studies. Out of 33 patients with obstruction, 28 (85%) had an RI of 0.7 or more, while 11 out of 24 patients (46%) without obstruction had an RI less than 0.7. CONCLUSION: The RI is promising as a new parameter to estimate the intraprostatic pressure to investigate BPH. Its value to represent urodynamic information during voiding remains to be studied.

Aged↗
PubMed2000

High hurdle of clinical trials to demonstrate efficacy of anticataractogenic drugs.

Recently, the rapid progression of cataract surgical technique has led cataract patients in industrialized countries to ignore the possibilities of drug therapy. Globally, however, it will be impossible in the near future to treat cataract by surgery alone, mainly due to medicoeconomic reasons. Preventative measures must be sought. As one of the these measures, the development of anticataractogenic drugs has reemerged as a focus in the lens research field. Although clinical trials of newly developed drugs are absolutely necessary before they enter the market, they have been considered to be a rather easy task. However, in order to gain accurate and reproducible data from trials, the trial program must be carefully prepared. The numbers of participants to the trial, the selection criteria of the subjects, the objective judgment of cataractous changes, follow-up period, a high technical level for cataract documentation and image analysis are proposed. Although there still remain some difficulties concerning the methods for objective judgment, a scientifically acceptable examination must be conducted.

Animals↗
PubMed2000

The Reykjavik Eye Study--prevalence of lens opacification with reference to identical Japanese studies.

PURPOSE: A population-based cataract epidemiological study, the Reykjavik Eye Study, was conducted to determine the prevalence and characteristics of lens opacities in Iceland. The results were compared with those from previous surveys in Japan to determine the influence of race and environmental factors. METHODS: 1,635 randomly selected residents of Reykjavik, Iceland, were enrolled, and among them, 1,045 responded and took part in the study. The subjects received ophthalmological examination of both the anterior and the posterior segments. Changes in the crystalline lens were examined and photographed under maximal pupillary dilation. Classification of the opacity types and grading of the extent of lens opacificiation were done using a standardized scheme, and the data were analyzed with Student's test, the chi(2) test and the Mantel-Haenszel test. RESULTS: The prevalence of lens opacities in subjects in their 50s, 60s, 70s and in those 80 years and older was 42.7, 61.0, 85.3 and 100%, respectively. Grade II and III lens opacities were found in 2. 2% of subjects in their 50s and in 10.5, 35.9 and 62.3% in their 60s, 70s, and over 80 years, respectively. Cortical opacities predominated in all age groups followed by nuclear opacities; subcapsular opacities, on the other hand, were quite rare. A unique type of opacity, i.e., granular opacity, seldom seen among the Japanese, was found in 6.6% of the Icelandic subjects. CONCLUSIONS: Our results show that cortical opacity is the major type of opacity in Icelandic subjects, although its prevalence was lower than that in the Japanese subjects. Interestingly, the first appearance of lens opacities of grades II and III in Icelanders was delayed by 10 years compared to the Japanese suggesting fewer or less severe risk factors for cataract formation in Iceland.

Aged↗
PubMed2000

Acupuncture on clinical symptoms and urodynamic measurements in spinal-cord-injured patients with detrusor hyperreflexia.

OBJECTIVES: We investigated the possible use of acupuncture for the treatment of urinary incontinence caused by detrusor hyperreflexia in patients with chronic spinal cord injuries. METHODS: A total of 13 patients (11 males, 2 females) suffering from urinary incontinence due to spinal cord injuries were treated by acupuncture, which was carried out with disposable stainless steel needles inserted into the bilateral BL-33 (Zhongliao) points on the skin of the third posterior sacral foramina. Urodynamic studies were also performed before acupuncture, immediately after the 1st acupuncture and 1 week after the 4th acupuncture. In 6 patients, these urodynamic studies were performed again 1 month after the 4th acupuncture. RESULTS: No side effects were recognized throughout the treatment period. Of the 13 patients, incontinence disappeared in 2 (15%) and decreased to 50% or less compared to baseline in a further 6 (46%). Maximum cystometric bladder capacity increased significantly from 76.2 +/- 62.3 to 148.1 +/- 81.5 ml 1 week after the 4th acupuncture (p < 0.01). In the 6 patients in whom cystometry was repeated 1 month after the 4th acupuncture, bladder capacity decreased from 187.5 +/- 90.4 ml 1 week after the 4th acupuncture to 128.3 +/- 93.4 ml. CONCLUSION: In spinal cord injury patients acupuncture could represent another valuable therapeutic alternative to the treatment of urinary incontinence caused by detrusor hyperreflexia.

Acupuncture Therapy↗
PubMed2000

Ghrelin, a novel growth hormone-releasing acylated peptide, is synthesized in a distinct endocrine cell type in the gastrointestinal tracts of rats and humans.

Ghrelin, a novel GH-releasing acylated peptide, was recently isolated from rat stomach. It stimulated the release of GH from the anterior pituitary through the GH secretagogue receptor (GHS-R). Ghrelin messenger RNA and the peptide are present in rat stomach, but its cellular source has yet to be determined. Using two different antibodies against the N- and C-terminal regions of rat ghrelin, we identified ghrelin-producing cells in the gastrointestinal tracts of rats and humans by light and electron microscopic immunohistochemistry and in situ hybridization combined with immunohistochemistry. Ghrelin-immunoreactive cells, which are not enterochromaffin-like cells, D cells, or enterochromaffin cells, accounted for about 20% of the endocrine cell population in rat and human oxyntic glands. Rat ghrelin was present in round, compact, electron-dense granules compatible with those of X/A-like cells whose hormonal product and physiological functions have not previously been clarified. The localization, population, and ultrastructural features of ghrelin-producing cells (Gr cells) indicate that they are X/A-like cells. Ghrelin also was found in enteric endocrine cells of rats and humans. Using two RIAs for the N- and C-terminal regions of ghrelin, we determined its content in the rat gastrointestinal tract. Rat ghrelin was present from the stomach to the colon, with the highest content being in the gastric fundus. Messenger RNAs of ghrelin and GHS-R also were found in these organs. Ghrelin probably functions not only in the control of GH secretion, but also in the regulation of diverse processes of the digestive system. Our findings provide clues to additional, as yet undefined, physiological functions of this novel gastrointestinal hormone.

Animals↗
PubMed2000

Ghrelin strongly stimulates growth hormone release in humans.

Ghrelin is a recently identified endogenous ligand for the GH secretagogue receptor and is involved in a novel system for regulating GH release. However, little is known about its GH-releasing activity and other endocrine effects in humans. To address this issue, we studied the GH, ACTH, cortisol, PRL, LH, FSH, and TSH responses to synthetic human ghrelin. In four normal male adults (28-37 yr), iv ghrelin administration released GH in a dose-dependent manner and 0.2, 1.0, and 5.0 microg/kg ghrelin produced 43.3 +/- 6.0, 81.5 +/- 12.7, and 107.0 +/- 10.7 ng/mL of the GH peak values at 30 min, respectively. ACTH, cortisol, and PRL levels were also elevated after ghrelin injection, while the lowest dose (0.2 microg/kg) resulted in only minimum peak values of these hormones (22.8 +/- 3.0 pg/mL, 9.4 +/- 1.9 microg/dL, and 4.6 +/- 0.6 ng/mL, respectively). There were no significant changes in LH, FSH, or TSH levels. This is the first study showing evidence that ghrelin strongly stimulates GH release in humans.

Adrenocorticotropic Hormone↗
PubMed2000

Development of a simple and efficient method for transformation of buckwheat plants (Fagopyrum esculentum) using Agrobacterium tumefaciens.

Apical meristems of seedlings of buckwheat (Fagopyrum esculentum var. Shinano No. 1) were pricked with a needle and inoculated with Agrobacterium tumefaciens (LBA4404, pBI121). The inoculated seedlings were grown to maturation and allowed to pollinate randomly to set the seeds (T1 plants). The transformation efficiency of the T1 plants was estimated by germination in the presence of geneticin (20 microg/ml) and by detection of beta-glucuronidase (GUS) gene with PCR, indicating that 36% and 70% of the T1 plants were transformed, respectively. Four plants taking on a mutated morphology were selected from T1 plants which were transformed with the method using A. tumefaciens harboring a modified pBI121 for plasmid rescue. Southern blot analysis of plasmids rescued from the 4 T1 plants demonstrated that each plasmid contained a different flanking DNA of the buckwheat genome, an evidence that T-DNA was integrated in different sites of the genomic DNA among the 4 T1 plants.

Agrobacterium tumefaciens↗
PubMed2000

Magnesium removal impairs the regulatory role of rat endothelium.

Vascular endothelium has been shown to play an important role in the regulation of vascular tone and, hence, impairment of the endothelium may induce hypertension. Although magnesium (Mg) deficiency could induce hypertension, the role of Mg on the endothelium is unclear. We examined the effects of Mg removal on endothelium-dependent and -independent responses using ring preparations of femoral arteries obtained from spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). Norepinephrine (10(-9)-10(-4) M) evoked concentration-dependent contractions in arteries with endothelium. The maximal response was greater in SHR than in WKY. Removal of external Mg augmented the contraction in WKY but not in SHR. As a result, the contraction obtained in arteries with endothelium was identical in the two groups. Removal of the endothelium enhanced the contraction in both strains, with a greater response occurring in WKY than in SHR in Krebs, but not in Mg-free, solution. As a result, in arteries without endothelium, the contractions were identical in WKY and SHR both in Krebs and Mg-free solutions. Acetylcholine (10(-9)-10(-4) M) evoked concentration-dependent relaxation in arteries with, but not in those without, endothelium obtained from WKY and SHR. The relaxation did not differ between the two strains, nor was it altered by Mg removal. Thus, Mg removal impairs inhibitory function of the endothelium against contraction induced by norepinephrine, without affecting endothelium-dependent relaxation in response to acetylcholine, in the rat femoral artery. The effect of Mg removal is not apparent in SHR. The fact that after removal of external Mg the contraction in response to norepinephrine in arteries with endothelium is identical in WKY and SHR suggests that a normotensive artery with Mg deficiency may mimic a hypertensive artery through endothelial impairment.

Acetylcholine↗