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Biomedical subjects

D Suzuki

Publications and source records attributed to D Suzuki.

At least 37 records · Page 2Linked to original sources
PubMed2000

Establishment of efficient reaggregation culture system for gene transfection into immature T cells by retroviral vectors.

To overcome low efficiency of retroviral infection into immature T cells, we modified reaggregation fetal thymus organ culture by closely packed co-culture with virus-producing cells (VPC). The viral vector was constructed in chimeric vector, pMX, with IRES and tailless-rat CD2 as a surface marker of infected cells. A rearranged TCR beta gene (Vbeta8.2) was further inserted into the construct for investigating effect of the introduced gene in T cell development. Using this system, we succeeded to transfer the viral vector into immature thymocytes at a remarkably higher efficiency compared to conventional methods using medium containing retrovirus. Moreover, the introduced TCR beta gene was expressed on thymocytes of RAG2-deficient mice to induce in the transition of CD4-CD8- double-negative (DN) into CD4+CD8+ double-positive (DP) cells by transducing beta-selection signaling. Thus, our modified reaggregation culture system is useful for studying the molecular mechanism of T cell development due to a highly efficient gene transfer into immature T cells.

Animals↗
PubMed2000

Hypovolemic ischemic optic neuropathy.

BACKGROUND: Ischemic optic neuropathy refers to an acute event of ischemia, or decreased blood flow, to the optic nerve resulting in varying degrees of vision loss and visual field defects. Typically this disease affects the elderly population who experience systemic diseases that compromise the blood flow efficiency of the optic nerve head (e.g., giant-cell arteritis, hypertension, diabetes, etc.). However, cases of blood loss to the optic nerve, secondary to traumatic injuries or surgeries, have also been shown to result in ischemic optic neuropathy, regardless of age. It seems that in these cases, the resulting anemia and hypotension play contributing roles in the development of ischemic optic neuropathy. METHODS: A 41-year-old black man came to us with optic nerve head pallor O.S., count-fingers vision O.S., positive afferent pupillary defect O.S., and a central scotoma O.S. after being hospitalized and treated for a stab wound to his left neck that severed his left carotid artery at the bifurcation. RESULTS: This patient had been seen in the Optometry Clinic two years before the stab-wound incident. At that time, he had 20/20 vision in his left eye and no remarkable neurological deficits. His ocular presentation after the traumatic hypovolemic event was probably a direct result of the hypoperfusion to the left optic nerve head. This patient was diagnosed with a hypovolemic, or blood loss-related, ischemic optic neuropathy (O.S.). CONCLUSIONS: Patients who experience large amounts of blood loss due to trauma, surgery, internal bleeding, etc. and report vision loss should be screened for possible optic nerve ischemia. As eye care providers, when we are presented with patients who have optic nerve head atrophy, we should inquire about events that may have precipitated blood loss, potentially triggering ischemic optic neuropathy.

Adult↗
PubMed1999

Glucose degradation product methylglyoxal enhances the production of vascular endothelial growth factor in peritoneal cells: role in the functional and morphological alterations of peritoneal membranes in peritoneal dialysis.

Peritoneal membrane permeability deteriorates in peritoneal dialysis (PD) patients. We test whether glucose degradation products (GDPs) in PD fluids, glyoxal, methylglyoxal and 3-deoxyglucosone, stimulate the production of vascular endothelial growth factor (VEGF), a factor known to enhance vascular permeability and angiogenesis. VEGF increased in cultured rat mesothelial and human endothelial cells exposed to methylglyoxal, but not to glyoxal or 3-deoxyglucosone. VEGF also increased in peritoneal tissue of rats given intraperitoneally methylglyoxal. VEGF and carboxymethyllysine (CML) (formed from GDPs) co-localized immunohistochemically in mesothelial layer and vascular walls of the peritoneal membrane of patients given chronic PD. By contrast, in the peritoneum of non-uremic subjects, VEGF was identified only in vascular walls, in the absence of CML. VEGF production induced by GDPs may play a role in the progressive deterioration of the peritoneal membrane.

Animals↗
PubMed1999

2-Isopropylidenehydrazono-4-oxo-thiazolidin-5-ylacetanilide (OPB-9195) treatment inhibits the development of intimal thickening after balloon injury of rat carotid artery: role of glycoxidation and lipoxidation reactions in vascular tissue damage.

We have pursued the hypothesis that the carbonyl modification of proteins by glycoxidation and lipoxidation reactions plays a role in atherogenesis. Human atherosclerotic tissues with fatty streaks and uremic arteriosclerotic tissues were examined, with specific antibodies, to detect protein adducts formed with carbonyl compounds by glycoxidation or lipoxidation reactions, i.e. advanced glycation end products (AGEs) or glycoxidation products, such as carboxymethyllysine (CML) and pentosidine, and lipoxidation products, such as malondialdehyde (MDA)-lysine and 4-hydroxy-nonenal (HNE)-protein adduct. All the four adducts were identified in the proliferative intima and in macrophage-rich fatty streaks. If the carbonyl modification is not a mere result but is a contributor to atherogenesis, inhibition of glycoxidation and lipoxidation reactions might prevent vascular tissue damage. We tested this hypothesis in rats following balloon injury of their carotid arteries, a model exhibiting a remarkable intimal thickening, which are stained positive for all the four adducts. Oral administration of 2-isopropylidenehydrazono-4-oxo-thiazolidin-5-ylacetanili de (OPB-9195), an inhibitor of both glycoxidation and lipoxidation reactions, in rats following balloon injury effectively prevented the intimal thickening. These data suggest a role for the carbonyl modification of proteins by glycoxidation and lipoxidation reactions in most, if not all, types of vascular tissue damage ('carbonyl stress'), and the usefulness of inhibitors of carbonyl reactions for the treatment of vascular tissue damage.

Aged↗
PubMed1999

Plasma calcium and calcitonin levels in eels fed a high calcium solution or transferred to seawater.

To examine the physiological role of calcitonin (CT) in calcium homeostasis of teleosts, we compared calcium and CT levels in freshwater eels fed a high calcium-consomme solution (Ca2+: 1.25 M; 1 ml/100 g body wt) into the stomach (Experiment I), and in freshwater eels transferred from freshwater to seawater (Experiment II). In experiment I, plasma calcium and CT levels in the high calcium-treated eels rapidly increased (calcium: 2.63 mM at 0 h to 8. 50 mM at 3 h; CT: below detection level at 0 h to 1118.2 pg/ml at 3 h). Plasma calcium and CT levels in the control eels remained below detection level during the 3 h of the experiment. In experiment II, the plasma CT levels did not increase, although the plasma calcium levels increased from 3.23 mM at 0 h to 4.10 mM at 8 h. Therefore, in eels, we demonstrate a correlation between plasma CT and plasma calcium raised by dietary calcium in the consomme form, but it does not participate in the initial processes of seawater adaptation.

Adaptation, Physiological↗
PubMed1999

Serum and urinary concentrations of heparan sulfate in patients with diabetic nephropathy.

BACKGROUND: Heparan sulfate (HS) contributes to the negative charge in the glomerular basement membrane (GBM), which may maintain the GBM charge barrier. Changes in sulfation and/or the concentration of HS may be associated with the development of diabetic nephropathy. METHODS: Using two different antibodies specific for HS chains, one that reacts with the N-sulfated sequences in HS chains (10E4) and the other that reacts with neo-epitope of HS, which occurs after heparitinase digestion of HS chains (3G10), we examined the serum and urinary concentrations of HS by enzyme-linked immunosorbent assay and performed immunohistochemical staining of glomeruli in diabetic patients with and without nephropathy. RESULTS: The level of urinary excretion of 10E4 binding HS/creatinine clearance was significantly reduced in diabetic patients when compared with that in nondiabetic subjects (P < 0.0001), and the level was more decreased in patients with overt nephropathy than in patients without overt nephropathy. No differences or only small differences were found between these groups in serum and urinary 3G10-binding HS and in serum 10E4-binding HS. Immunohistochemical staining with these antibodies was consistent with the findings in the urine. CONCLUSIONS: The results suggest that a decreased HS N-sulfation exists in the urine, which may reflect a structural change or an altered processing of HS within the GBM. Because N-sulfation plays a key role in determining the extent of sulfation within the HS chains, the decreased urinary 10E4-binding HS may have potential implications with regard to the development of diabetic nephropathy.

Adult↗
PubMed1999

Increased carbonyl modification by lipids and carbohydrates in diabetic nephropathy.

BACKGROUND: In diabetic nephropathy (DN), possible mediators of untoward effects of hyperglycemia include the advanced glycation end products (AGEs). Indeed, an AGE, carboxymethyllysine (CML), accumulates in expanded mesangial matrix and nodular lesions. An advanced lipoxidation end product (ALE), malondialdehyde-lysine (MDA-lysine), generated on proteins during lipid peroxidation also accumulates in these lesions. As both ALEs and AGEs are formed by carbonyl amine chemistry between protein and carbonyl compounds derived from autoxidation of lipids and carbohydrates, their colocalization suggests an increased carbonyl modification of proteins. METHODS: To address this hypothesis, human diabetic renal tissues were examined to characterize carbonyl modification of proteins by lipids and carbohydrates: (a) ALEs, MDA-lysine and 4-hydroxynonenal (HNE) protein adduct, derived from lipids, and (b) AGEs, pentosidine and CML, derived from carbohydrates. Furthermore, to elucidate the biological effect of carbonyl modification on primary cultured human and rat mesangial cells, the intracellular protein phosphorylation was examined in the presence of various kinds of carbonyl compounds. RESULTS: The ALE and AGE adducts examined were identified in expanded mesangial matrix and nodular lesions. The exposure of cultured mesangial cells to carbonyl compounds resulted in phosphorylation of tyrosine residues of a number of intracellular proteins. CONCLUSIONS: These data suggest a broad derangement in nonenzymatic biochemistry involving both lipids and carbohydrates exists in diabetic glomerular lesions ("carbonyl stress").

Animals↗
PubMed1999

A sensitive and specific ELISA for plasma pentosidine.

BACKGROUND: Advanced glycation end products are formed by non-enzymatic glycation and oxidation reaction. Pentosidine is a well-known and characterized structure among them, and has been implicated in the pathogenesis of complications associated with chronic renal failure and long-term dialysis, such as dialysis-related amyloidosis and atherosclerosis. METHODS: We established a highly sensitive and specific competitive enzyme-linked immunosorbent assay (ELISA) for plasma pentosidine and applied it to large numbers of plasma samples including haemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) patients. We compared their plasma pentosidine levels determined by the competitive ELISA with those determined by high-performance liquid chromatographic (HPLC) assay currently used. RESULTS: The plasma pentosidine levels determined by the ELISA were correlated well with those determined by sophisticated instrumental HPLC assay, both in non-diabetic and diabetic dialysis patients. Both analyses yielded comparable results, with over 8-fold higher plasma pentosidine levels in HD and CAPD patients, irrespective of the presence or absence of diabetes, as compared to normal subjects and non-uraemic diabetic patients. CONCLUSIONS: The competitive ELISA will provide a rapid and convenient determination of plasma pentosidine content and thus be useful to assess the carbonyl stress in uraemic patients.

Adult↗
PubMed1999

Expression of megsin mRNA, a novel mesangium-predominant gene, in the renal tissues of various glomerular diseases.

Mesangial cells play an important role in maintaining a structure and function of the glomerulus and in the pathogenesis of glomerular diseases. Recently, we discovered a new mesangium-predominant gene termed "megsin." Megsin is a novel protein that belongs to the serine protease inhibitor (serpin) superfamily. To elucidate the pathophysiologic role of megsin in the kidney, the expression and localization of megsin mRNA in renal tissues of patients with IgA nephropathy (IgA-N), diabetic nephropathy (DN), minimal change nephrotic syndrome (MCNS), membranous nephropathy (MN), and normal human kidney (NHK) was evaluated by in situ hybridization using digoxigenin-labeled oligonucleotide. Individual cells positive for megsin mRNA were observed only in glomeruli in all renal tissues. Their localization coincided with those of mesangial cells. The percentage of positive cells for megsin mRNA in total glomerular cells was significantly greater in IgA-N than in MCNS, MN, and NHK. It was also significantly greater in DN than in MCNS and NHK. In IgA-N, the percentage of megsin mRNA-positive cells was greater in tissues from those with mesangial cell proliferation and slightly mesangial matrix expansion (periodic acid-Schiff-positive area in the total glomerulus area, <30%; cell number in mesangial matrix area, >30; assessed in cross-sections through their vascular poles) than in tissues from those with severe mesangial matrix expansion (periodic acid-Schiff-positive area in total glomerulus area, >30%; cell number in mesangial matrix area, <30). In conclusion, megsin mRNA was predominantly expressed in glomerular mesangial cells in all renal tissues. The expression of megsin mRNA was upregulated in IgA-N and DN, both of which are diseases accompanied with mesangial cell proliferation and/or mesangial matrix expansion. These data suggest a link of megsin expression to the pathogenesis of IgA-N and DN, two major causes of end-stage renal failure.

Actins↗
PubMed1999

Immunohistochemical evidence for an increased oxidative stress and carbonyl modification of proteins in diabetic glomerular lesions.

Advanced glycation end products (AGE) include a variety of protein adducts whose accumulation has been implicated in tissue damage associated with diabetic nephropathy (DN). It was recently demonstrated that among AGE, glycoxidation products, whose formation is closely linked to oxidation, such as carboxymethyllysine (CML) and pentosidine, accumulate in expanded mesangial matrix and nodular lesions in DN, in colocalization with malondialdehyde-lysine (MDA-lysine), a lipoxidation product, whereas pyrraline, another AGE structure whose deposition is rather independent from oxidative stress, was not found within diabetic glomeruli. Because CML, pentosidine, and MDA-lysine are all formed under oxidative stress by carbonyl amine chemistry between protein amino group and carbonyl compounds, their colocalization suggests a local oxidative stress and increased protein carbonyl modification in diabetic glomerular lesions. To address this hypothesis, human renal tissues from patients with DN or IgA nephropathy were examined with specific antibodies to characterize most, if not all, carbonyl modifications of proteins by autoxidation products of carbohydrates, lipids, and amino acids: CML (derived from carbohydrates, lipids, and amino acid), pentosidine (derived from carbohydrates), MDA-lysine (derived from lipids), 4-hydroxynonenal-protein adduct (derived from lipids), and acrolein-protein adduct (derived from lipids and amino acid). All of the protein adducts were identified in expanded mesangial matrix and nodular lesions in DN. In IgA nephropathy, another primary glomerular disease leading to end-stage renal failure, despite positive staining for MDA-lysine and 4-hydroxynonenal-protein adduct in the expanded mesangial area, CML, pentosidine, and acrolein-protein adduct immunoreactivities were only faint in glomeruli. These data suggest a broad derangement in nonenzymatic biochemistry in diabetic glomerular lesions, and implicate an increased local oxidative stress and carbonyl modification of proteins in diabetic glomerular tissue damage ("carbonyl stress").

Adult↗
PubMed1999

Apolipoprotein E2/E5 variants in lipoprotein glomerulopathy recurred in transplanted kidney.

Lipid abnormalities are associated with various disorders ranging from generalized atherosclerosis to renal diseases, including lipoprotein glomerulopathy that is characterized by glomerular lipoprotein thrombi and causes type III hyperlipoproteinemia, proteinuria, and renal failure. This study examines lipoprotein glomerulopathy, which recurred in a transplanted kidney. Molecular biologic analysis of the patient's apolipoprotein (apo) E gene demonstrated E2/E5 type variants. Immunohistochemical analysis of the diseased kidney demonstrated various lipid peroxidation-specific protein adducts, suggesting a potential role of oxidative stress in this disorder. Recurrence in the transplanted kidney suggested a pathogenic role of extraglomerular humoral component(s) resulting from abnormal lipoprotein metabolism, presumably linked to apo E and other genetic or acquired factor(s). Furthermore, the finding that the patient showed pathologic abnormalities in the transplanted kidney with no clinical signs or symptoms of renal disease indicated that lipoprotein glomerular damage progresses early before any clinical manifestations.

Adult↗
PubMed1999

Carbonyl stress in the pathogenesis of diabetic nephropathy.

Diabetic nephropathy is a major chronic complication of diabetes mellitus and an important cause of increased morbidity and mortality in diabetic patients. Although several lines of evidence have suggested that poor glycemic control undoubtedly plays a significant role, the metabolic events responsible for its development are not understood well. Possible mediators of untowards effects of hyperglycemia include the advanced glycation end products (AGEs). AGEs, carboxymethyllysine and pentosidine, whose formation is closely linked to oxidation, accumulate in the characteristic diabetic glomerular lesions, such as the expanded mesangial matrix and nodular lesions, in co-localization with other oxidation-specific protein adducts, such as malondialdehyde-lysine, 4-hydroxynonenal-protein adduct, and acrolein-protein adduct. These five biomarkers are formed under oxidative stress by carbonyl amine chemistry between protein amino group and carbonyl compounds derived from carbohydrates, lipids, and amino acids. This article focuses on new aspects of the pathology of diabetic nephropathy, implicating an increased oxidative stress and carbonyl modification of proteins by autoxidation products of carbohydrates, lipids, and amino acids in diabetic glomerular tissue damage ("carbonyl stress").

Amino Acids↗
PubMed1998

A mesangium-predominant gene, megsin, is a new serpin upregulated in IgA nephropathy.

Mesangial cells play an important role in maintaining a structure and function of the glomerulus and in the pathogenesis of glomerular diseases. To identify a specific gene expressed in human mesangial cells, we used a rapid large-scale DNA sequencing and computerized data processing to compare the transcripts in cultured human mesangial cells with various different cells and organs. Using this novel approach, we discovered a new mesangium-predominant gene termed "megsin." We obtained a full-length cDNA clone of megsin, which coded for a novel 380-amino acid protein. Amino acid homology search revealed that megsin belonged to the serpin (serine protease inhibitor) superfamily. The amino acid sequences in the reactive loop site of megsin showed characteristic features of functional serpins. Northern blot and reverse-transcribed PCR analyses of various tissues and cells demonstrated that megsin was predominantly expressed in human mesangial cells. In situ hybridization studies showed the megsin expression in the mesangium of normal glomeruli, while it increased in the expanded mesangium of glomeruli from patients with IgA nephropathy with the degree of mesangial proliferation. Here we report a new human mesangium-predominant gene that may function as an inhibitory serpin in normal and abnormal biological processes of glomerulus.

Amino Acid Sequence↗
PubMed1998

Protein-bound acrolein: potential markers for oxidative stress.

Acrolein (CH2==CH---CHO) is known as a ubiquitous pollutant in the environment. Here we show that this notorious aldehyde is not just a pollutant, but also a lipid peroxidation product that could be ubiquitously generated in biological systems. Upon incubation with BSA, acrolein was rapidly incorporated into the protein and generated the protein-linked carbonyl derivative, a putative marker of oxidatively modified proteins under oxidative stress. To verify the presence of protein-bound acrolein in vivo, the mAb (mAb5F6) against the acrolein-modified keyhole limpet hemocyanin was raised. It was found that the acrolein-lysine adduct, Nepsilon-(3-formyl-3, 4-dehydropiperidino)lysine, constitutes an epitope of the antibody. Immunohistochemical analysis of atherosclerotic lesions from a human aorta demonstrated that antigenic materials recognized by mAb5F6 indeed constituted the lesions, in which intense positivity was associated primarily with macrophage-derived foam cells and the thickening neointima of arterial walls. The observations that (i) oxidative modification of low-density lipoprotein with Cu2+ generated the acrolein-low-density lipoprotein adducts and (ii) the iron-catalyzed oxidation of arachidonate in the presence of protein resulted in the formation of antigenic materials suggested that polyunsaturated fatty acids are sources of acrolein that cause the production of protein-bound acrolein. These data suggest that the protein-bound acrolein represents potential markers of oxidative stress and long-term damage to protein in aging, atherosclerosis, and diabetes.

Acrolein↗
PubMed1998

Follow-up study on urinary type IV collagen in patients with early stage diabetic nephropathy.

Type IV collagen is a major component released from the glomerular and tubular basement membranes. To investigate the alteration of renal type IV collagen turnover in early stage diabetic nephropathy, urinary type IV collagen was measured by a highly sensitive one-step sandwich enzyme immunoassay (EIA). Urinary samples were obtained from 94 diabetic patients without overt proteinuria. Among those patients, 61 were normoalbuminuric and 33 patients were in the microalbuminuric group. Levels of urinary type IV collagen were serially examined at the start of this study and again one year later. The levels of urinary type IV collagen in patients in the microalbuminuric group were significantly higher than those in the normoalbuminuric group (P < 0.01). There was a significant correlation between the concentration of urinary albumin and urinary type IV collagen in both groups (P < 0.05). Twenty-eight patients (45.3%) in the normoalbuminuric group who showed an abnormal elevation of urinary type IV collagen in comparison to the reference range of normal healthy adults (normal range; less than 3.5 microg/g x Cr). Seven (25%) out of these 28 normoalbuminuric patients with increased urinary type IV collagen progressed to the microalbuminuric group one year later. The levels of urinary type IV collagen in such patients were significantly increased. In the 21 patients who stayed within the normoalbuminuric group, the urinary type IV collagen levels were significantly decreased one year later. It appears that the levels of urinary type IV collagen might reflect ongoing alteration of the extracellular matrix (ECM) turnover and might define more specifically the early stage diabetic nephropathy than the detection of microalbuminuria. It is concluded that the serial measurement of urinary type IV collagen can be a useful marker for detecting renal injury in diabetes.

Adult↗
PubMed1997

In situ hybridization studies of matrix metalloproteinase-3, tissue inhibitor of metalloproteinase-1 and type IV collagen in diabetic nephropathy.

Progressive expansion of the mesangial matrix is one of the most characteristic histological features of diabetic nephropathy (DN). To determine the balance between the turnover and degradation of extracellular matrix (ECM) in renal tissue of patients with DN, we examined the expression of matrix metalloproteinase-3 (MMP-3), tissue inhibitor of metalloproteinase-1 (TIMP-1) and type IV collagen (IV-C) mRNAs using a high-resolution in situ hybridization. Patients were divided into three grades: mild (grade I), moderate (grade II) and severe (grade III) mesangial expansion and tubulointerstitial injury. The relationship between the expression of these mRNAs and degree of glomerular mesangial expansion and interstitial injury was also examined. Cells positive for each mRNA were observed in glomerular resident cells, including glomerular mesangial, epithelial and endothelial cells and cells of Bowman's capsule. A number of tubular epithelial cells and some infiltrating cells in the interstitium also expressed these mRNAs. The expression of MMP-3 mRNA and TIMP-1 mRNA was strongest in glomeruli of grade I and inversely correlated with mesangial expansion. In contrast, the expression of all three types of mRNA was correlated with the degree of interstitial injury. Our results indicate that IV-C, MMP-3 and TIMP-1 mRNAs are expressed in glomerular resident cells, tubular epithelial cells and infiltrating cells in renal tissue of DN, and suggest that their expression changes with the degree of mesangial expansion and interstitial injury. Altered expression of MMP-3 and TIMP-1 may be associated with the progression of DN.

Adult↗
PubMed1997

A diabetic case with hemoglobin J-Meerut and low HbA1C levels.

A diabetic patient with hemoglobin (Hb) J-Meerut and low HbA1C levels is reported. An automatic glycohemoglobin analyzer used for the determination of HbA1C revealed an abnormal peak of the peripheral blood obtained from a Japanese female with diabetes. She showed a lower HbA1C level (3.7%) than expected from her fasting plasma glucose (172 mg/dl). High performance liquid chromatography and isoelectric focusing indicated that her abnormal hemoglobin was Hb J-Meerut [alpha 120(H3)Ala-->Glu] and it accounted for 28.3% of the total hemoglobin. Abnormal hemoglobinemia should be considered when a major discrepancy between the levels of HbA1C and fasting plasma glucose is observed.

Blood Glucose↗