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Biomedical subjects

M Arakawa

Publications and source records attributed to M Arakawa.

At least 37 records · Page 2Linked to original sources
PubMed2001

Expression, roles, receptors, and regulation of osteopontin in the kidney.

Osteopontin (OPN) is a secreted glycoprotein in both phosphorylated and non-phosphorylated forms. It contains an Arg-Gly-Asp cell-binding sequence and a thrombin-cleavage site. OPN is mainly present in the loop of Henle and distal nephrons in normal kidneys in animals and humans. After renal damage, OPN expression may be significantly up-regulated in all tubule segments and glomeruli. Studies utilizing OPN gene-deficient mice, antisense-treated or anti-OPN-treated animals have demonstrated that OPN promotes accumulation of macrophages, and may play a role in macrophage-mediated renal injury, but that the effect may be mild and short-lived. On the other hand, OPN has some renoprotective actions in renal injury, such as increasing tolerance to acute ischemia, inhibiting inducible nitric oxide synthase and suppressing nitric oxide synthesis, reducing cell peroxide levels and promoting the survival of cells exposed to hypoxia, decreasing cell apoptosis and participating in the regeneration of cells. In addition, OPN is associated with renal stones, but whether it acts as a promoter or inhibitor of stone formation is controversial. It has been demonstrated that OPN receptors include two families: integrin and CD44. The OPN integrin receptors include alpha(v)beta(3), alpha(v)beta(1), alpha(v)beta(5) and alpha(9)beta(1), and alpha(4)beta(1). In normal human kidneys, standard CD44 is expressed most dominantly. Different OPN functions are mediated via distinct receptors. Parathyroid hormone, vitamin D(3), calcium, phosphate and some cytokines increase OPN expression in vitro or in vivo, whereas female sex hormones and angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists decrease OPN expression in some renal damage states.

Animals↗
PubMed2001

Real-time observation of hemodynamic changes in glomerular aneurysms induced by anti-Thy-1 antibody.

BACKGROUND: Blood flow in the microvasculature plays a pivotal role in determining the outcome of injury and repair in inflamed tissue. Real-time observation of the kidney microvasculature, including the glomerular capillary tufts, is extremely difficult because of the methodological limitations of currently available microscope optics. In the present study, we attempted to analyze hemodynamic events that occurred in vivo during microvascular regeneration following destruction of the glomerular capillary tuft, functionally and quantitatively by the use of a real-time confocal laser-scanning microscope (CLSM) system. METHODS: A polyethylene catheter was inserted into the carotid artery to allow blood pressure measurement. Mesangiolytic lesions producing microaneurysms were induced by the injection of anti-Thy-1.1 antibody. On days 3 and 7 after antibody injection, we examined hemodynamic changes under an intravital microscope equipped with real-time CLSM in combination with a high-speed CCD video camera. To measure vessel diameter and erythrocyte velocity, rats were injected with fluorescein isothiocyanate (FITC)-labeled dextran and FITC-labeled red blood cells (RBCs). RESULTS: On day 3 of the disease, mean arterial blood pressure was 112 +/- 5 mm Hg, which was significantly higher than that of normal rat or of rats on day 7 (93 +/- 1 and 101 +/- 9 mm Hg, respectively). Within mircroaneurysms on day 3, RBC velocity was greatly suppressed. By day 7, RBC velocity, in glomeruli with normal appearances, recovered to about half of the level seen in normal controls (430.6 +/- 284.7 microm/sec), while in narrowed glomerular tufts, it was still only 104.6 +/- 35.1 microm/sec. CONCLUSIONS: The noninvasive procedure, using CLSM in combination with a high-speed video camera, allowed us to examine hemodynamic events quantitatively and to analyze microvascular architecture three dimensionally in the kidney. It is useful for estimating hemodynamic response and vascular regeneration in vivo and may be promising for clinical application.

Aneurysm↗
PubMed2001

Expression of osteopontin in gentamicin-induced acute tubular necrosis and its recovery process.

BACKGROUND: There is controversy regarding the exact localization and roles of osteopontin (OPN), a multipotential chemokine, in renal injury. There is little information on the expression and role of OPN in gentamicin-induced acute tubular necrosis (ATN) and its recovery process. METHODS: A severe ATN model was made using male Wistar rats by injecting gentamicin (150 mg/kg/day) for five days and limiting the provision of water. The expression and localization of OPN mRNA and protein, ED1 as a macrophage marker, proliferating cellular nuclear antigen (PCNA), CD44 as an OPN receptor, megalin as a proximal tubule marker, and their relationships to each other were examined from the early tubular necrotic period to the late recovery period by Northern blotting, in situ hybridization, and double immunohistochemical staining. RESULTS: In the gentamicin group, OPN mRNA and protein were expressed in only the PCNA-positive proliferating cortical distal tubules, not in the necrotic proximal tubules, until day 6 after the first administration, but were found markedly in PCNA-positive regenerative proximal and distal tubules on days 10, 15, and 30. The localization of PCNA-positive cells was almost always accompanied with the up-regulated expression of OPN using quantitative analysis (P < 0.01). CD44 expression was markedly up-regulated in the renal cortical tubular epithelium from days 6 to 30. In the control group, no expression of OPN and CD44 in the cortical area was found throughout the experimental period. CONCLUSIONS: These results suggested that OPN is related to the proliferation and regeneration of tubular epithelial cells after tubular damage.

Animals↗
PubMed2001

Novel glomerular lipoprotein deposits associated with apolipoprotein E2 homozygosity.

BACKGROUND: Hyperlipoproteinemia is occasionally associated with severe glomerular injury caused by abnormal accumulation of lipid in glomeruli, which occurs in conditions such as lipoprotein glomerulopathy (LPG). This study investigates the cases of two siblings with homozygous apolipoprotein (apo) E2 who show unique histologic features, massive proteinuria, and dysbetalipoproteinemia. METHODS: Histologic studies were performed using renal biopsy specimens. Plasma lipoproteins were extensively characterized. The exons of the apo E genes were sequenced to avoid missing any mutations. RESULTS: Histologically, the siblings' condition resembled LPG by light microscopy studies. Electron microscopy studies revealed large lipoid deposits in the paramesangium, subendothelium, and subepithelium of the glomeruli, which were different from LPG in terms of not forming the layered structure resembling a fingerprint even in large lipoprotein thrombi, and mesangial foam cells. Immunohistochemically, the lipoid deposits contained apo E and apo B. These patients did not have either diabetic nephropathy or other known forms of glomerulonephritis. The sequence of exons of the apo E genes revealed homozygosity for apo E2 in both cases. CONCLUSION: The extensive lipoprotein deposition in glomeruli, which resembles LPG, can also occur in apo E2 homozygous individuals, but in a distinct fashion. Because the two cases were siblings, they may have other shared alleles, in addition to the apo E2 allele, that negatively affect processing of lipoproteins and lead to abnormal accumulation of lipoprotein deposits in glomeruli.

Amino Acid Sequence↗
PubMed2001

Different effects of St John's wort on the pharmacokinetics of simvastatin and pravastatin.

OBJECTIVE: St John's Wort, a widely used herbal product, is an inducer of CYP3A4 and it decreases blood concentrations of CYP3A4 substrates. The effects of St John's Wort on the pharmacokinetics of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors simvastatin (an inactive lactone pro-drug) and pravastatin were determined in this study. METHODS: Sixteen healthy male subjects (n = 8 in group 1 and n = 8 in group 2) took a St John's Wort caplet (300 mg) or matching placebo three times a day for 14 days in a double-blind, crossover study. On day 14, a single oral dose of 10 mg simvastatin and 20 mg pravastatin was given to subjects in group 1 and group 2, respectively. Blood samples were obtained during a 24-hour period after the administration of each drug. RESULTS: Repeated St John's Wort treatment tended to lower plasma simvastatin concentration and significantly (P <.05) lowered concentrations of simvastatin hydroxy acid, its active metabolite. The peak concentration in plasma (ratio, 0.72 of placebo) of simvastatin hydroxy acid tended to be decreased and its area under the plasma concentration-time curve between time zero and 24 hours after administration (ratio, 0.48 of placebo) was significantly decreased (P <.05) by St John's Wort. On the other hand, St John's Wort did not influence plasma pravastatin concentration. No significant differences were observed in the elimination half-life of simvastatin or pravastatin between the placebo and St John's Wort trials. CONCLUSIONS: This study showed that St John's Wort decreases plasma concentrations of simvastatin but not of pravastatin. Because simvastatin is extensively metabolized by CYP3A4 in the intestinal wall and liver, which are induced by St John's Wort, it is likely that this interaction is partly caused by the enhancement of the CYP3A4-mediated first-pass metabolism of simvastatin in the small intestine and liver.

Adult↗
PubMed2001

Membranoproliferative glomerulonephritis associated with hypocomplementemic urticarial vasculitis after complete remission of membranous nephropathy.

A 49-year-old-man developed proteinuria in 1978. He was diagnosed as having membranous nephropathy by renal biopsy and was treated with prednisolone. The proteinuria disappeared completely and the treatment was stopped. In 1995, after complete remission, he developed nephrotic syndrome with chronic urticaria and hypocomplementemia. Renal biopsy revealed membranoproliferative glomerulonephritis (type I) and skin biopsy showed leukocytoclastic vasculitis, which was compatible with hypocomplementemic vasculitis syndrome. Steroid therapy was very effective.

Anti-Inflammatory Agents↗
PubMed2001

The circadian blood pressure rhythm in non-diabetic hemodialysis patients.

This study investigates the circadian blood pressure variation of non-diabetic chronic hemodialysis (HD) patients on both HD and non-HD days as well as the factors affecting diurnal BP variation. Forty-nine HD patients aged 61.8 +/- 12.9 years who were on daytime HD for 97 +/- 68 months were studied. No significant difference was found in every daytime and nighttime BP between the first (HD) and the second (non-HD) day. However, the ratio nighttime/daytime BP was significantly higher on the second day. Each BP diurnal variability pattern was classified as either Dipper (D: the ratio nighttime/daytime mean BP 0.8-0.9), non-dipper (0.9 < ND < 1.0), or inverted dipper (ID > 1.0). More than 75% of the cases were classified as ND (26 cases) or ID (11 cases). The ultrafiltration rate in D was significantly less than that in ND and ID. The difference of plasma renin activity between pre- and post-HD (dRen) was significantly higher in ID than in D and ND. The amount of dialysis (Kt/V) was found to be significantly correlated with nighttime BP fall. Ultrafiltration, dRen and Kt/V were independent factors for the abnormal BP diurnal variability. In conclusion, the decreased nocturnal BP fall seen in non-diabetic HD patients is associated with increased extracellular fluid even in the patients without overt overhydration, whereas relatively insufficient amount of dialysis (low Kt/V) may be another possible cause. The increased dRen observed only in ID patients may reflect occult cardiovascular damage or functional disturbances in aortic and carotid baroreflexes caused by arterial structural changes.

Adult↗
PubMed2001

Determination of optimal blood pressure for patients with IgA nephropathy based on renal histology.

To evaluate the optimal BP control for patients with IgA nephropathy (IgAN) based on the histologic severity of the nephropathy and the degree of renal dysfunction. We analyzed 332 consecutive renal biopsy specimens and clinical data from patients with IgAN. Patients were divided into three groups based on their BP at the time of biopsy: an optimal BP (SBP<120 mmHg and DBP<80 mmHg), a hypertensive BP (SBP > or = 140 mmHg and/or DBP > or = 90 mmHg), and an intermediate BP group. Each biopsy specimen was evaluated for mesangial proliferation, degree of sclerosis and/or hyalinosis of the arterioles and the interlobular artery using a semiquantitative method. Creatinine clearance and the percentage of sclerosed glomeruli were also determined. Both the degree of renal dysfunction and the histologic changes correlated significantly with BP, even in patients with a BP <140/90 mmHg. The patients with an optimal BP at the time of biopsy had significantly less histologic damage with respect to mesangial proliferation and vessel changes than those with an intermediate or hypertensive BP. In the patients with a hypertensive BP, the percentage of sclerotic glomeruli was significantly higher and the creatinine clearance was significantly lower. The optimal BP proposed by the WHO in 1999 prevents histologic evidence of renal damage for patients with IgAN.

Adult↗
PubMed2001

Three-dimensional analysis of nephrogenesis in the neonatal rat kidney: light and scanning electron microscopic studies.

In order to clarify the process of renal development more precisely than previously, the present study observed the rat neonatal kidney by scanning electron microscopy (SEM) of KOH digested tissue as well as by light microscopy of plastic sections. In the subcapsular region, aggregation of the mesenchymal cells was closely associated with the upper side of the ureteric duct ampulla. These mesenchymal cells projected a number of fine irregular processes at the basal portion facing the ureteric duct. A spherical cluster transformed from the mesenchymal cell aggregation was found on the lower side of the terminal ampulla, and was differentiated into the renal vesicle. Some cells at the top of the renal vesicle formed a cone-shaped projection and invaded the ureteric duct ampulla, forming a connection with it. In the advanced stage, a shallow transverse cleft appeared on the outer lateral side of the renal vesicle, and a second cleft was formed on the opposite side close to the junction between the renal vesicle and the ampulla. As the two clefts deepened, the vesicle assumed the well-known S-shaped body. In the advanced S-shaped body, the lower limb became cup-shaped, while the segment between the middle and lower limbs of the "S" elongated to form a tubular structure (i.e., the prospective proximal tubule and Henle's loop). The upper limb of the "S" also increased its length to form a distal tubule. The middle limb of the "S", however, was attached firmly to the cup-shaped lower limb (i.e., the prospective renal corpuscle) and was considered to become the macula densa of the mature nephron. In the maturing renal corpuscle, irregularly shaped cells were observed as a sheet-like aggregation at its vascular pole and were continuous with the vascular smooth muscle cells. These findings will help toward a better understanding of the morphological complexities of nephrogenesis.

Animals↗
PubMed2001

[Lung involvement in rapidly progressive glomerulonephritis].

The purpose of this study is to evaluate pulmonary involvement in rapidly progressive glomerulonephritis (RPGN). Of 71 patients in whom RPGN was diagnosed, 32 (45.1%) had pulmonary involvement: 12, alveolar hemorrhage (AH) (16.9%); 10, interstitial pneumonia (IP) (14.1%); four, chronic bronchial lesions (5.6%); two, consolidation (2.8%), and four, old inflammatory lesions (5.6%). Investigation of which organ of the twelve AH patients, the kidney or the lung, was the first to be involved, showed that the lung preceded in one patient, the kidney was first in three, and the lung and kidney occurred at the same time in the other eight. Of the ten IP patients, the lung preceded in eight, the kidney was ahead in two, and lung and kidney were simultaneous in one. Three patients had a history of pneumoconiosis, and two had acute progressive IP. Seventeen (45.9%) of 37 patients who tested positive for antineutrophil cytoplasmic autoantibodies (MPO-ANCA) had lung involvement, and three (30.0%) of the ten patients who tested negative for MPO-ANCA, PR 3-ANCA and anti-GBM antibody also had lung involvement.

Aged↗
PubMed2001

MR imaging underestimates stromal invasion in patients with adenocarcinoma of the uterine cervix.

PURPOSE OF INVESTIGATION: To evaluate magnetic resonance (MR) imaging in assessing the depth of stromal invasion in patients with adenocarcinoma of the uterine cervix. METHODS: Twenty-three women with adenocarcinoma of the cervix underwent T2-weighted and dynamic MR imaging before surgical evaluation. The images were evaluated for the depth of stromal invasion and compared with histological results. RESULTS: Twelve of 23 patients (52%) were correctly diagnosed in agreement with the histological findings. However, the depth of stromal invasion was underestimated in ten patients (44%). In four of nine patients who exhibited scattered type lesions, no lesions were detected by MR imaging, although deep stromal invasion (more than 1/3) was recognized histologically. In contrast, all 11 patients showed cancer lesions in solid type adenocarcinomas with deep stromal invasion. CONCLUSION: MR imaging detected less stromal invasive lesions in adenocarcinoma of the cervix than surgical specimens, and some scattered type adenocarcinomas could not be visualized.

Adenocarcinoma↗
PubMed2001

[Susceptibilities of bacteria isolated from patients with lower respiratory infectious diseases to antibiotics (1999)].

From October 1999 to September 2000, we collected the specimen from 430 patients with lower respiratory tract infections in 17 institutions in Japan, and investigated the susceptibilities of isolated bacteria to various antibacterial agents and antibiotics and patients' characteristics. Of 515 strains that were isolated from specimen (mainly from sputum) and assumed to be bacteria causing in inflammation, 506 strains were investigated. The breakdown of the isolated bacteria were: Staphylococcus aureus 78, Streptococcus pneumoniae 101, Haemophilus influenzae 104, Pseudomonas aeruginosa (non-mucoid) 58, P. aeruginosa (mucoid) 11, Moraxella subgenus Branhamella catarrhalis 41, Klebsiella pneumoniae 18, etc. Of 78 S. aureus strains, those with 4 micrograms/ml or above of MIC of oxacillin (methicillin-resistant S. aureus: MRSA) occupied 57.7%. Vancomycin and arbekacin showed the most potent activities against MRSA without detection of ABK-resistant strain (MIC: 64 micrograms/ml) and decrease of VCM-sensitive strains those were found in 1998. The frequency of S. pneumoniae exhibiting low sensitivity to penicillin (penicillin-intermediate S. pneumoniae: PISP + penicillin-resistant S. pneumoniae: PRSP) decreased to 34.7% from 46.0% in 1998. The frequency of PRSP was 3.0%, being the least number after 1991. Carbapenems showed strong activities against S. pneumoniae. Especially, panipenem inhibited the growth of all 101 strains with MIC of 0.063 microgram/ml. Generally, all drugs showed strong activities against H. influenzae with MIC80s of 4 micrograms/ml or below. MICs of ofloxacin ranged between 0.063 microgram/ml and 4 micrograms/ml in 1998, however, those were 0.125 microgram/ml or below in all H. influenzae in 1999 showing the strongest activity. Tobramycin and ciprofloxacin showed strong activities against P. aeruginosa (both mucoid and non-mucoid) with MIC80s of 1 microgram/ml. Number of isolated P. aeruginosa (mucoid) was little as 11, however, the susceptibilities to all drugs were better than P. aeruginosa (non-mucoid). K. pneumoniae showed good susceptibilities to all drugs except for ampicillin with decreasing of low-sensitive strains compared to those detected in 1998. Also, all drugs generally showed strong activities against M. (B.) catarrhalis. MIC80s of all drugs were 2 micrograms/ml or below. The drug which showed the strongest activity was imipenem inhibiting all 41 strains with MIC of 0.063 microgram/ml. On the patients' characteristics, the number of patients aged 80 years or older who had been increased was decreased in 1999 in the distribution by age. The percentage of the elderly patients aged 70 years or older was 47.0%, which occupied almost a half number of the total patients as in the last year. As for the incidence by disease, bacterial pneumonia and chronic bronchitis were the highest. They were noted in 37.9% and 30.5% of the patients, respectively. In 1999, bronchial asthma was frequently observed as compared in recent years. It was noted in about 10% of the patients which is the same % as in bronchiectasis. We examined the number of strains from these patients with infections before and after administration of antibiotics. In patients with bacterial pneumonia, the number of isolated strains was almost the same between those before and after administration. However, in patients with chronic bronchitis, the number of strains remarkably decreased to less than the half of the total after administration of antibiotics in the last year, but it decreased to 2/3 of the total in 1999. On the administration of antibiotics and isolated bacteria by the day of administration, the bacteria which were isolated more before administration were H. influenzae in 28.4%, S. pneumoniae in 25.7%, M. (B.) catarrhalis in 12.0% and S. aureus in 10.6%. The frequency of S. aureus after administration over 15 days was almost the same as that before administration, but the frequency of P. aeruginosa (both mucoid and non-mucoid) was 36.8% which was higher than that before administration. The frequency of isolated S. pneumoniae was decreased after administration and none of them was isolated after completion of administration. However, that of H. influenzae was decreased to 7.1% after administration within 3 days, and many H. influenzae were isolated after completion of administration as 21.4%.

Adolescent↗
PubMed2001

The three-dimensional structure of the neonatal mouse kidney as revealed by scanning electron microscopy after KOH treatment.

The shape and arrangement of the developing nephrons were studied three-dimensionally by scanning electron microscopy (SEM) of the neonatal mouse kidney. The specimens were treated with the KOH digestion method in order to remove extracellular connective tissue components, thus enabling the direct observation of the developing nephrons at various stages. At the subcapsular region of the renal cortex, the ureteric ducts were observed as branched tubules with terminal swellings or ampullae. Newly formed blood vessels were often associated with terminals of these ureteric ducts. The cup-shaped renal corpuscles had aggregations of mesangial cells with blood vessels in the groove. At the vascular pole of mature nephrons, extraglomerular mesangial cells were observed as a cellular sheet, which was continuous with the smooth muscle layer of afferent and efferent blood vessels. The present study also demonstrated the shape of the immature podocytes in relation to the endothelial morphology of glomerular capillaries.

Aging↗
PubMed2001

[Characterization of cryoglobulin, M protein, low molecular weight IgM in a patient with chronic hepatitis C and type II mixed cryoglobulinemia].

The common extrahepatic manifestation of hepatitis C virus(HCV) infection is mixed cryoglobulinemia. We have analyzed serum cryoglobulin, IgM and various antibody activities from a patient with chronic hepatitis C and type II cryoglobulinemia. Cryoprecipitates were consisted of polyclonal IgG and monoclonal IgM-kappa with rheumatoid factor activity. About 20% of total IgM was found to be low molecular weight IgM by gel-filtration and SDS-PAGE. The anti-streptolysin O(ASO) activity measured by Latex agglutination method was found to be markedly elevated despite normal activity by Rantz-Randell method. The patient's serum has revealed to react against bovine gamma globulin, which crosslinked streptolysin O to Latex particles, in a nonspecific manner. Phenotypic analysis of the surface markers on abnormal lymphoid cells from peripheral blood and bone marrow showed monoclonal expansion of B-cell lineage by flow cytometry. The patient was treated with interferon-alpha, which resulted in an improvement of liver dysfunction, decreased amounts of cryoglobulin and IgM. It was concluded that the patient has suffered from lymphoproliferative disorder, namely HCV infection-associated primary macroglobulinemia.

Aged↗
PubMed2000

Characterization and chromosomal mapping of a novel human gene, ANKHZN.

Ankhzn (ankyrin repeats hooked to a zinc finger motif) was originally isolated by means of the gene trap method, as a novel cytoplasmic protein on mouse embryonic stem cells. The Ankhzn protein is ubiquitously expressed in a spatiotemporal-specific manner and is located on endosomes. In the present study, we have cloned human ANKHZN cDNA by PCR using candidate EST clones exhibiting a high homology to mouse Ankhzn cDNA. The human ANKHZN cDNA encoded a 1166aa protein exhibiting 84.9% identity to the mouse one. The size of the transcript was found to be about 7kb on a Northern blot analysis, and ANKHZN mRNA was found to be ubiquitously expressed in human tissues on RT-PCR analysis. Western blot analysis showed that a 130kDa protein was detected at various levels in human tissues and also present in both membrane and soluble fractions obtained on subcellular fractionation. Human ANKHZN is a single copy gene consisting of predicted 25 exons in the human genome, and has been mapped to human chromosome 17p13 by radiation hybrid panel and fluorescence in-situ hybridization.

Amino Acid Sequence↗