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").

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").

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.

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.

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.

Significance of urinary type IV collagen in patients with diabetic nephropathy using a highly sensitive one-step sandwich enzyme immunoassay

Urinary concentrations of type IV collagen in patients with diabetic nephropathy were measured by a highly sensitive, one-step sandwich enzyme immunoassay. Samples from 298 patients with noninsulin-dependent diabetes mellitus (NIDDM) and 80 healthy controls were examined. In diabetic patients with macroalbuminuria or renal insufficiency, the concentrations of urinary type IV collagen were significantly higher than those of diabetic patients with normoalbuminuria or healthy controls (P < 0.001). Urinary type IV collagen concentration in diabetic patients with microalbuminuria was significantly higher than that in diabetic patients with normoalbuminuria or that in healthy controls (P < 0.001). In contrast, there were no significant changes in the concentration of serum type IV collagen between microalbuminuric patients and normoalbuminuric patients. The area under the receiver operating characteristic (ROC) curve for the urinary type IV collagen concentration was equivalent to that of urinary albumin. It was concluded that urinary type IV collagen concentration determined using this method might be a useful marker for the early detection of diabetic nephropathy.

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.

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.

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.

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.

Changes of expression of complement 3bi receptors on granulocytes after physical exercise in rats

OBJECTIVE

The purpose of this study was to examine the effects of physical exercise on the expression of clusters of differentiation (CD)11b, CD18 and CD 54 on granulocytes and complement 3bi (C3bi)-dependent functions in rats.

EXPERIMENTAL DESIGN

The rats were separated into two groups: the control group (n = 21) and the training group (n = 14). The rats in the training group were subjected to a program that consisted of swimming 6 days in a week for 7 weeks.

MEASURES

The phagocytic and hydrogen peroxide (H2O2) generating activities and the expression of receptors on granulocytes were measured using flow cytometric techniques.

RESULTS

The acute swimming and the 7 weeks of swim training caused high C3bi-dependent phagocytic activity of granulocytes. Swim training led to an increase of H2O2 generating activity together with C3bi-dependent phagocytosis both immediately after and 24 hrs after the 120 min swimming. The 24 hrs recovery from the 120 min swimming in trained and untrained rats caused an increase of H2O2 generating activity of granulocytes. In the training group, an increase in this activity could be observed immediately after the 120 min swimming exercise. The upregulation of the CI1b on granulocytes was induced by the 120 min of swimming regardless of swim training.

CONCLUSIONS

These results suggest that the increase of C3bi receptor-dependent phagocytosis and H2O2 generating activities induced by the physical exercise might depend on the upregulation of the CD11b that is the component of C3bi receptor.

Immunofluorescence staining of renal biopsy samples in patients with diabetic nephropathy in non-insulin-dependent diabetes mellitus using monoclonal antibody to reduced glycated lysine

This is the first report on immunofluorescence staining of renal biopsy samples in human diabetic nephropathy (DN) using monoclonal antibodies to reduced glycated lysine. In order to detect the localization of glycated lysine in the mesangial matrix and/or the glomerular basement membrane (GBM), we examined immunofluorescence staining using antibodies against reduced glycated lysine in the glomeruli of 16 patients with DN and ten age-matched patients with diffuse mesangial proliferative glomerulonephritis without IgA deposition (DPGN) as controls. In the early stage of DN, immunofluorescence microscopy revealed the presence of intense staining for reduced glycated lysine in the GBM as well as in part of the tubular basement membrane, but not in the mesangial area. In contrast, immunofluorescence microscopy revealed less staining for glycated lysine in the GBM in the advanced stage of DN, and no reaction with any part of the renal tissue in patients with DPGN. It was concluded that detection of reduced glycated lysine in GBM in the early stage of DN might be associated with the initial pathogenesis of this disease.

Localization of glycated proteins in the glomeruli of patients with diabetic nephropathy

Glycation of proteins is regarded as one of the major causes of the development and progression of diabetic nephropathy. Based on the numerous reports on experimental models and on our own newly developed techniques, we planned to localize Amadori products and advanced glycation end-products (AGEs), as well as the mRNA expression of cytokines, enzymes and their inhibitors, which are responsible for the expansion of the mesangial areas of the glomeruli. Ten patients with diabetic nephropathy were examined. Patients with immunoglobulin (Ig) A nephropathy and normal portions of the surgically removed kidneys served as controls. Amadori products and AGEs in biopsy specimens were stained by specific monoclonal antibodies, and mRNA expression of the above substances was detected by in situ hybridization. There was a parallel progression in the degree of staining with anti-Amadori product antibody or anti-AGE antibody with the severity of tissue damage in patients with diabetic nephropathy. Patients with IgA nephropathy and normal renal tissues did not show any positive staining with these antibodies. The expression of transforming growth factor beta 1, stromelysin and tissue inhibitor of matrix proteinase 1 in the glomeruli was decreased in diabetic patients with advanced tissue damage, but they were progressively expressed in the advanced stage of IgA nephropathy. It is concluded that Amadori products and of AGEs were formed in parallel in diabetic kidneys. The decrease in the expression of the cytokine and enzymes might be due to altered protein formation associated with glycation.

In situ hybridization of interleukin 6 in diabetic nephropathy

Increased mesangial expansion is one of the most characteristic histological changes in diabetic nephropathy (DN). Although the pathogenesis of DN remains unclear, recent studies associate interleukin (IL) 6 with mesangial proliferative glomerulonephritis. To elucidate the expression and localization of IL-6 mRNA in renal tissues of patients with DN, a high-resolution in situ hybridization using digoxigenin-labeled oligonucleotide was performed. Patients were divided into three groups based on light microscopy findings: mild (group 1), moderate (group 2), and severe (group 3) mesangial expansion. The relationship between the expression of IL-6 mRNA and the degree of glomerular mesangial expansion in DN was examined. Individual cells positive for IL-6 mRNA were observed in glomeruli. These cells were mesangial cells, glomerular epithelial cells, and Bowman's capsule. The signal intensity was strongest in tissues from group 2 but was weak in those from groups 1 and 3. Most cells in the area of mesangial proliferation were strongly stained for IL-6 mRNA, and few positive cells were found in the Kimmelstiel-Wilson nodular lesion. In the interstitium, some tubules, particularly atrophic tubules, and some infiltrating cells were positively stained for IL-6 mRNA. The interstitial expression of IL-6 mRNA correlated significantly with the degree of interstitial injury and was remarkable in tissues from groups 2 and 3. We conclude that IL-6 mRNA is expressed by glomerular resident cells and interstitial cells in the renal tissue of patients with DN and that its expression may be associated with mesangial proliferation and may be involved in the tissue injury of DN.

Urinary albumin fragments as a new clinical parameter for the early detection of diabetic nephropathy

Urinary albumin fragments (uAF) from patients with NIDDM were analyzed as a possible factor in the early discovery of diabetic nephropathy before emergence of microalbuminuria. SDS-PAGE and immunoblot assay were employed for detection of uAF. Samples from 252 patients with NIDDM, 158 patients with non-diabetic diseases, and 48 healthy volunteers were examined; uAF were detected in 139 (55.2%), 94 (59.5%), only one (2.1%), respectively. In diabetic patients with normoalbuminuria, uAF were detected in 48 out of 159 cases (30.2%). Two years after the initial study, 3 of the 17 diabetic patients (17.6%) with normoalbuminuria and uAF showed micro- or macroalbuminuria. It was concluded that detection of uAF might be useful for the early detection of diabetic nephropathy in NIDDM.

Differential distribution of type IV collagen chains in patients with diabetic nephropathy in non-insulin-dependent diabetes mellitus

Thickening of the glomerular basement membrane (GBM) and expansion of the mesangial matrix are hallmarks of human diabetic nephropathy. Renal tissues from 15 patients with type II (non-insulin-dependent) diabetes (NIDDM) were studied by immunofluorescence (IF) and immunogold electron microscopy (IEM) for the distribution of 2 type IV collagen peptides [alpha 3(IV) noncollagenous (NC) domain and alpha 4(IV) NC domain] and 2 classical type IV collagen chains [alpha 1(IV) NC domain and alpha 2(IV) domain]. There was intense staining for alpha 3(IV) NC and alpha 4(IV) NC domain in the GBM but not in the mesangial matrix of patients with overt diabetic nephropathy. In contrast, staining with antibodies to alpha 1(IV) NC and alpha 2(IV) NC domain reacted with mesangial matrix but was significantly decreased in the GBM in the patients with overt diabetic nephropathy. IEM confirmed the IF findings. These data suggest that expansion of the mesangial matrix and thickening of GBM in NIDDM involves separate and distinct type IV collagen components and that the site-specific matrix alterations in NIDDM and type I (insulin-dependent) diabetes are parallel.

Significance of high levels of serum IgA and IgA-class circulating immune complexes (IgA-CIC) in patients with non-insulin-dependent diabetes mellitus

Significance of serum IgA and IgA-class circulating immune complexes (IgA-CIC) elevation in patients with non-insulin-dependent diabetes mellitus (NIDDM) was described. Seventeen patients with NIDDM and 17 patients with diffuse mesangial proliferative glomerulonephritis without deposition of IgA (DPGN) as controls were examined. The levels of serum IgA in patients with NIDDM were significantly higher than those in patients with DPGN (p < or = 0.01). The levels of IgA-CIC in patients with NIDDM were also significantly higher than those in patients with DPGN (p < or = 0.01). Production of IgA derived from B cells and the proportion of IgA bearing B cells in patients with NIDDM were not significantly higher than those in patients with DPGN. Furthermore, the levels of IgA in pharyngeal washings from diabetic patients were not significantly higher than those for DPGN patients. Duration of diabetes, the level of HbA1c, and the presence of hypertension, microalbuminuria, or retinopathy showed no significant correlations with the levels of serum IgA or IgA-CIC in patients with NIDDM. It was postulated that the elevations of serum IgA and IgA-CIC were based on subclinical infection of the mucosa and/or deterioration of IgA clearance in patients with NIDDM.

Measurement of the extracellular matrix in glomeruli from patients with diabetic nephropathy using an automatic image analyzer

To elucidate the characteristics of glycoproteins in the mesangial matrix in glomeruli from patients with diabetic nephropathy (DN) in non-insulin-dependent diabetes mellitus (NIDDM), we examined periodic acid-Shiff (PAS) and immunofluorescence staining of types III (III-C), IV (IV-C), V (V-C) and VI (VI-C) collagen, fibronectin (FN), fibrinogen (FBG) and laminin (LN) in the glomeruli of 16 patients with DN and 12 patients with diffuse proliferative glomerulonephritis (DPGN). The percentage of positively staining areas in the glomeruli were calculated using an automatic image analyzer. The percentages of areas positive for PAS, III-C, IV-C, V-C, VI-C or FN in DN were significantly greater than those in DPGN. Moreover, the percentages of PAS-positive areas were significantly correlated with not only IV-C-positive areas, but also FN-positive areas in patients with DN. The percentages of PAS-positive areas were also significantly correlated with the levels of serum creatinine and the degree of proteinuria in these patients. It was concluded that mesangial expansion in this disease might be associated mainly with an increase in IV-C and FN. These changes appear to affect the deterioration of renal function and the appearance of proteinuria, and vice versa.

Genetic predisposing factors in non-insulin dependent diabetes with persistent albuminuria

We designed this study to elucidate a possible involvement of genetic factors which influence the progression of renal dysfunction in patients with non-insulin dependent diabetes mellitus (NIDDM). A total of 328 patients was randomly selected in the Tokai University Hospital. They had been cared for in our hospital as NIDDM for the past five years, until April, 1989. Fifty-six patients with persistent albuminuria, and an equal number of patients without persistent albuminuria were included in this study. No significant differences were observed between the two groups in terms of age, estimated period of illness, blood pressure, body-mass index, HbAlc, blood glucose, total cholesterol, triglyceride level and mean blood pressure. The family histories obtained by questionnaires revealed that there might be some genetic predisposing factors leading to the onset of nephropathy in patients with NIDDM, especially in cases with paternal high blood pressure. It is suggested that paternal hypertension might be related to the development of nephropathy in patients with NIDDM.

A case of insulin-secreting tumor successfully treated with diazoxide

A 72-year-old patient was referred to our hospital because of a hypoglycemic crisis possibly due to an insulin secreting-tumor. Although its localization was assumed to be at the head of the pancreas as assessed by transhepatic venography with sampling, no mass lesion was detected by selective angiography, ultrasound, computerized axial tomography, magnetic resonance imaging and 67Ga-citrate scan. The patient was treated with diazoxide, because of poor localization and his age, insulin secretion was improved after both 30 and 60 min in the 75 g oral glucose tolerance test. The total amount of urinary C-peptide excretion decreased from 70.8 to 29.2 mcg/day. Thereafter, no hypoglycemic symptoms were observed during his admission. No side effects except mild liver damage were observed.

Significance of levels of circulating IgA-class immune complex in discriminant analysis of patients with IgA nephropathy before renal biopsy

Discriminant analysis of clinical markers including circulating IgA-class immune complex (IgA-CIC) before renal biopsy in patients with IgA nephropathy is described. Fifty-six patients with IgA nephropathy (IgA nephropathy group) and 54 patients with other primary chronic glomerulonephritis (non-IgA nephropathy group) were examined. Discriminant analysis was applied to separate these two groups by using 21 clinical markers including levels of IgA-CIC. The levels of IgA-CIC in sera were measured by a solid-phase anti-C3 Facb enzyme immunoassay (EIA). Among these clinical markers, the levels of serum IgA, IgA-CIC and creatinine, and the degree of microhematuria in the IgA nephropathy group were significantly higher than those in the non-IgA nephropathy group. Contributions of IgA and IgA-CIC to the classification were very high and both had almost the same effect. The correct classification rate was 80.00% using five clinical markers: serum IgA, microhematuria, IgA-CIC, serum creatinine, and blood urea nitrogen. It was shown that the levels of serum IgA and IgA-CIC were major markers for the clinical diagnosis of patients with IgA nephropathy. It was concluded that discriminant analysis before renal biopsy was useful for the diagnosis of IgA nephropathy.

Fibrinolysis in patients with diabetic nephropathy determined by plasmin-alpha 2 plasmin inhibitor complexes in plasma

Activation of fibrinolysis in patients with diabetic nephropathy was determined by the plasma levels of plasmin-alpha 2 plasmin inhibitor complexes (alpha 2PIC) using a one-step sandwich enzyme immunoassay (EIA). Plasma levels of alpha 2PIC in diabetic patients with persistent proteinuria were significantly higher than those in diabetic patients without proteinuria, patients with chronic glomerulonephritis, and healthy adults. Plasma levels of alpha 2PIC in diabetic patients with intermittent proteinuria were also significantly higher than those of diabetic patients without proteinuria, patients with chronic glomerulonephritis, and healthy adults. Diabetic patients have been suggested to have a hypercoagulable state. The findings obtained from this study indicated that activation of fibrinolysis might counteract the hypercoagulable state in patients with diabetic nephropathy.

Eleven distinct VH gene families and additional patterns of sequence variation suggest a high degree of immunoglobulin gene complexity in a lower vertebrate, Xenopus laevis

Lower vertebrate species, including Xenopus laevis, exhibit restricted antibody diversity relative to higher vertebrates. We have analyzed more than 180 VH gene-containing recombinant clones from an unamplified spleen cDNA library by selective sequencing of JH and CH positive clones following iterative hybridization screening with family-specific VH probes, 11 unique families of VH genes, each associated with a unique genomic Southern blot hybridization pattern, are described and compared. Considerable variation in the number of hybridizing components detected by each probe is evident. The nucleotide sequence difference between VH families is as great as, if not more than, that reported in other systems, including representatives of the mammalian, avian, and elasmobranch lineages. Some Xenopus Ig gene families encode alternative amino acids at positions that are otherwise invariant or very rarely substituted in known Igs. Furthermore, variations in complementarity determining region sequences among members of the same gene family and high degrees of DH and JH region complexity are described, suggesting that in at least this lower vertebrate species, the diversity of expressed Ig VH genes is not restricted.

Systemic toxicity of botulinum toxin by intramuscular injection in the monkey

Botulinum toxin (Oculinum) was injected intramuscularly into eight monkeys. The LD50 dose is estimated to be approximately 39 U/kg body weight. The lowest dose that caused systemic toxicity, 33 U/kg, was close to the fatal dose range, 38-42 U/kg.

An interview with David Suzuki [by Charlotte Gray]

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