Revised equations for estimated GFR from serum creatinine in Japan

BACKGROUND

Estimation of glomerular filtration rate (GFR) is limited by differences in creatinine generation among ethnicities. Our previously reported GFR-estimating equations for Japanese had limitations because all participants had a GFR less than 90 mL/min/1.73 m2 and serum creatinine was assayed in different laboratories.

STUDY DESIGN

Diagnostic test study using a prospective cross-sectional design. New equations were developed in 413 participants and validated in 350 participants. All samples were assayed in a central laboratory.

SETTING & PARTICIPANTS

Hospitalized Japanese patients in 80 medical centers. Patients had not participated in the previous study.

REFERENCE TEST

Measured GFR (mGFR) computed from inulin clearance.

INDEX TEST

Estimated GFR (eGFR) by using the modified isotope dilution mass spectrometry (IDMS)-traceable 4-variable Modification of Diet in Renal Disease (MDRD) Study equation using the previous Japanese Society of Nephrology Chronic Kidney Disease Initiative (JSN-CKDI) coefficient of 0.741 (equation 1), the previous JSN-CKDI equation (equation 2), and new equations derived in the development data set: modified MDRD Study using a new Japanese coefficient (equation 3), and a 3-variable Japanese equation (equation 4).

MEASUREMENTS

Performance of equations was assessed by means of bias (eGFR - mGFR), accuracy (percentage of estimates within 15% or 30% of mGFR), root mean squared error, and correlation coefficient.

RESULTS

In the development data set, the new Japanese coefficient was 0.808 (95% confidence interval, 0.728 to 0.829) for the IDMS-MDRD Study equation (equation 3), and the 3-variable Japanese equation (equation 4) was eGFR (mL/min/1.73 m2) = 194 x Serum creatinine(-1.094) x Age(-0.287) x 0.739 (if female). In the validation data set, bias was -1.3 +/- 19.4 versus -5.9 +/- 19.0 mL/min/1.73 m2 (P = 0.002), and accuracy within 30% of mGFR was 73% versus 72% (P = 0.6) for equation 3 versus equation 1 and -2.1 +/- 19.0 versus -7.9 +/- 18.7 mL/min/1.73 m(2) (P < 0.001) and 75% versus 73% (P = 0.06) for equation 4 versus equation 2 (P = 0.06), respectively.

LIMITATION

Most study participants had chronic kidney disease, and some may have had changing GFRs.

CONCLUSION

The new Japanese coefficient for the modified IDMS-MDRD Study equation and the new Japanese equation are more accurate for the Japanese population than the previously reported equations.

Erythropoietin receptor is expressed in rat hippocampal and cerebral cortical neurons, and erythropoietin prevents in vitro glutamate-induced neuronal death

Recently, erythropoietin has been shown to be produced by astrocytes and its production is hypoxia-inducible. In the present study, we demonstrated, using a reverse transcription-polymerase chain reaction assay and immunostaining of the cells, that the erythropoietin receptor was expressed in cultured hippocampal and cerebral cortical neurons of day 19 rat embryo. Erythropoietin protected the cultured neurons from glutamate neurotoxicity. Neurons cultured for seven to 10 days were exposed to glutamate for 15 min and after culture for a further 24 h in the absence of glutamate the neuron survival was assayed. Significant protection was observed with erythropoietin from 3 pM (c. 100 pg/ml) in a dose-dependent manner. The protection was completely reversed by co-application of a soluble erythropoietin receptor, an extracellular domain capable of binding with erythropoietin. For exhibition of the neuroprotective effect, exposure of neurons to erythropoietin approximately 8 h prior to exposure to glutamate was required. Experiments with the inhibitors indicated that RNA and protein syntheses were necessary for the protection. However, exposure to erythropoietin for a short period (5 min or less) was sufficient to elicit the protective effect. The protective effect of erythropoietin was blocked by the simultaneous addition of EGTA. These findings and the previous finding that erythropoietin induces a rapid and transient increase in intracellular Ca2+ concentration in neuronal cells suggest that erythropoietin plays a neuroprotective role in brain injury caused by hypoxia or ischemia and that erythropoietin-induced Ca2+ influx from outside of the cells is a critical initial event yielding an enhanced resistance of the neurons to glutamate toxicity.

Estimation of glomerular filtration rate by the MDRD study equation modified for Japanese patients with chronic kidney disease

BACKGROUND

Accurate estimation of the glomerular filtration rate (GFR) is crucial for the detection of chronic kidney disease (CKD). In clinical practice, GFR is estimated from serum creatinine using the Modification of Diet in Renal Disease (MDRD) study equation or the Cockcroft-Gault (CG) equation instead of the time-consuming method of measured clearance for exogenous markers such as inulin. In the present study, the equations originally developed for a Caucasian population were tested in Japanese CKD patients, and modified with the Japanese coefficient determined by the data.

METHODS

The abbreviated MDRD study and CG equations were tested in 248 Japanese CKD patients and compared with measured inulin clearance (Cin) and estimated GFR (eGFR). The Japanese coefficient was determined by minimizing the sum of squared errors between eGFR and Cin. Serum creatinine values of the enzyme method in the present study were calibrated to values of the noncompensated Jaffé method by adding 0.207 mg/dl, because the original MDRD study equation was determined by the data for serum creatinine values measured by the noncompensated Jaffé method. The abbreviated MDRD study equation modified with the Japanese coefficient was validated in another set of 269 CKD patients.

RESULTS

There was a significant discrepancy between measured Cin and eGFR by the 1.0xMDRD or CG equations. The MDRD study equation modified with the Japanese coefficient (0.881xMDRD) determined for Japanese CKD patients yielded lower mean difference and higher accuracy for GFR estimation. In particular, in Cin 30-59 ml/min per 1.73 m(2), the mean difference was significantly smaller with the 0.881xMDRD equation than that with the 1.0xMDRD study equation (1.9 vs 7.9 ml/min per 1.73 m(2); P < 0.01), and the accuracy was significantly higher, with 60% vs 39% of the points deviating within 15%, and 97% vs 87% of points within 50%, respectively (both P < 0.01). Validation with the different data set showed the correlation between eGFR and Cin was better with the 0.881xMDRD equation than with the 1.0xMDRD study equation. In Cin less than 60 ml/min per 1.73 m(2), the accuracy was significantly higher, with 85% vs 69% of the points deviating within 50% (P < 0.01), respectively. The mean difference was also significantly smaller (P < 0.01). However, GFR values calculated by the 0.881xMDRD equation were still underestimated in the range of Cin over 60 ml/min per 1.73 m(2).

CONCLUSIONS

Although the Japanese coefficient improves the accuracy of GFR estimation of the original MDRD study equation, a new equation is needed for more accurate estimation of GFR in Japanese patients with CKD stages 3 and 4.

Modification of the CKD epidemiology collaboration (CKD-EPI) equation for Japanese: accuracy and use for population estimates

INTRODUCTION

We previously reported a modification to the Modification of Diet in Renal Disease (MDRD) Study equation for use in Japan. Recently, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) developed a new equation that is more accurate and yields a lower CKD prevalence estimate in the United States than the MDRD Study equation. We modified the CKD-EPI equation for use in Japan, compared its accuracy with the Japanese modification of the MDRD Study equation, and compared the prevalence of CKD in Japan using both equations.

DESIGN

A diagnostic test study comparing the Japanese coefficient-modified CKD-EPI equation and Japanese coefficient-modified MDRD Study equation and a cross-sectional study comparing distribution of estimated glomerular filtration rate and prevalence of CKD in participants in a Japanese annual health check program.

SETTING & PARTICIPANTS

763 Japanese patients (413 for development and 350 for validation) were included. Prevalence estimates were based on 574,024 participants from the annual health check program.

INDEX TEST

Japanese modification of the MDRD Study and CKD-EPI equations.

REFERENCE TEST

Inulin clearance.

RESULTS

The Japanese coefficient of the modified CKD-EPI equation was 0.813 (95% CI, 0.794-0.833). In the validation data set, the modified CKD-EPI equation performed better than the modified MDRD Study equation. Bias (measured GFR [mGFR] - eGFR) was 0.4 +/- 17.8 (SD) versus 1.3 +/- 19.8 mL/min/1.73 m(2) overall, respectively (P = 0.02); 7.3 +/- 20.6 versus 7.8 +/- 22.2 mL/min/1.73 m(2) for participants with mGFR >or=60 mL/min/1.73 m(2), respectively (P < 0.001); and -4.4 +/- 13.8 versus -3.3 +/- 15.6 mL/min/1.73 m(2) for participants with mGFR <60 mL/min/1.73 m(2), respectively (P = 0.5). The modified CKD-EPI equation yields a lower estimated prevalence of CKD than the modified MDRD Study equation (7.9% vs 10.0%), primarily because of a lower estimated prevalence of stage 3 (5.2% vs 7.5%).

LIMITATION

Most study participants had CKD. The study population contained a limited number of participants with mGFR >or=90 mL/min/1.73 m(2).

CONCLUSION

The Japanese coefficient-modified CKD-EPI equation is more accurate than the Japanese coefficient-modified MDRD Study equation and leads to a lower estimated prevalence of CKD in Japan.

AIM-1: a mammalian midbody-associated protein required for cytokinesis

Mitosis is a highly coordinated process that assures the fidelity of chromosome segregation. Errors in this process result in aneuploidy which can lead to cell death or oncogenesis. In this paper we describe a putative mammalian protein kinase, AIM-1 (Aurora and Ipl1-like midbody-associated protein), related to Drosophila Aurora and Saccharomyces cerevisiae Ipl1, both of which are required for chromosome segregation. AIM-1 message and protein accumulate at G2/M phase. The protein localizes at the equator of central spindles during late anaphase and at the midbody during telophase and cytokinesis. Overexpression of kinase-inactive AIM-1 disrupts cleavage furrow formation without affecting nuclear division. Furthermore, cytokinesis frequently fails, resulting in cell polyploidy and subsequent cell death. These results strongly suggest that AIM-1 is required for proper progression of cytokinesis in mammalian cells.

Modular activation of nuclear factor-kappaB transcriptional programs in human diabetic nephropathy

Diabetic nephropathy (DN) is the leading cause of end-stage renal failure and a major risk factor for cardiovascular mortality in diabetic patients. To evaluate the multiple pathogenetic factors implicated in DN, unbiased mRNA expression screening of tubulointerstitial compartments of human renal biopsies was combined with hypothesis-driven pathway analysis. Expression fingerprints obtained from biopsies with histological diagnosis of DN (n = 13) and from control subjects (pretransplant kidney donors [n = 7] and minimal change disease [n = 4]) allowed us to segregate the biopsies by disease state and stage by the specific expression signatures. Functional categorization showed regulation of genes linked to inflammation in progressive DN. Pathway mapping of nuclear factor-kappaB (NF-kappaB), a master transcriptional switch in inflammation, segregated progressive from mild DN and control subjects by showing upregulation of 54 of 138 known NF-kappaB targets. The promoter regions of regulated NF-kappaB targets were analyzed using ModelInspector, and the NF-kappaB module NFKB_IRFF_01 was found to be specifically enriched in progressive disease. Using this module, the induction of eight NFKB_IRFF_01-dependant genes was correctly predicted in progressive DN (B2M, CCL5/RANTES, CXCL10/IP10, EDN1, HLA-A, HLA-B, IFNB1, and VCAM1). The identification of a specific NF-kappaB promoter module activated in the inflammatory stress response of progressive DN has helped to characterize upstream pathways as potential targets for the treatment of progressive renal diseases such as DN.

Abnormal asymmetries in subcortical brain volume in schizophrenia

Subcortical structures, which include the basal ganglia and parts of the limbic system, have key roles in learning, motor control and emotion, but also contribute to higher-order executive functions. Prior studies have reported volumetric alterations in subcortical regions in schizophrenia. Reported results have sometimes been heterogeneous, and few large-scale investigations have been conducted. Moreover, few large-scale studies have assessed asymmetries of subcortical volumes in schizophrenia. Here, as a work completely independent of a study performed by the ENIGMA consortium, we conducted a large-scale multisite study of subcortical volumetric differences between patients with schizophrenia and controls. We also explored the laterality of subcortical regions to identify characteristic similarities and differences between them. T1-weighted images from 1680 healthy individuals and 884 patients with schizophrenia, obtained with 15 imaging protocols at 11 sites, were processed with FreeSurfer. Group differences were calculated for each protocol and meta-analyzed. Compared with controls, patients with schizophrenia demonstrated smaller bilateral hippocampus, amygdala, thalamus and accumbens volumes as well as intracranial volume, but larger bilateral caudate, putamen, pallidum and lateral ventricle volumes. We replicated the rank order of effect sizes for subcortical volumetric changes in schizophrenia reported by the ENIGMA consortium. Further, we revealed leftward asymmetry for thalamus, lateral ventricle, caudate and putamen volumes, and rightward asymmetry for amygdala and hippocampal volumes in both controls and patients with schizophrenia. Also, we demonstrated a schizophrenia-specific leftward asymmetry for pallidum volume. These findings suggest the possibility of aberrant laterality in neural pathways and connectivity patterns related to the pallidum in schizophrenia.

Mass spectrometry proves under-O-glycosylation of glomerular IgA1 in IgA nephropathy

BACKGROUND

The IgA1 molecule, which is predominantly deposited in glomeruli in IgA nephropathy (IgAN), is a unique serum glycoprotein because it has O-glycan side chains in its hinge region. Our study was conducted to investigate the O-glycan structure in the glomerular IgA1 in IgAN.

METHODS

The IgA1 was separated from 290 renal biopsy specimens of 278 IgAN patients and from four serum IgA1 samples (IgAN, 2; control, 2). The variety of O-glycan glycoform was determined by estimating the precise molecular weights of the IgA1 hinge glycopeptides using matrix-assisted laser desorption ionization time of flight mass spectrometry.

RESULTS

The peak distribution of IgA1 hinge glycopeptides clearly shifted to lesser molecular weights in both glomerular and serum IgA1 in IgAN compared with the serum IgA1 of controls. In the five major peaks of IgA1 hinge glycopeptides in each sample, the numbers of carbohydrates composing O-glycans (GalNAc, Gal, and NANA) in the deposited and serum IgA1 in IgAN patients were significantly fewer than those in the serum IgA1 in the control groups.

CONCLUSION

The O-glycan side chains in the hinge of the glomerular IgA1 were highly underglycosylated in IgAN. These results indicate that the decreased sialylation and galactosylation of the IgA1 hinge glycopeptides play a crucial role in its glomerular deposition in IgAN.

Implication of an increased oxidative stress in the formation of advanced glycation end products in patients with end-stage renal failure

Recent studies have demonstrated a marked increase in the level of advanced glycation end products (AGEs) in the plasma, skin and amyloid fibrils of hemodialysis (HD) patients. The presence of AGEs in (beta2m) forming amyloid fibrils has been established in a previous immunochemical study relying on a monoclonal anti-AGE antibody. In the present study, Western blot analysis and immunohistochemistry reveal that the epitope recognized by this antibody is N epsilon-(carboxymethyl)lysine (CML) and that CML is one of the AGE structures present in amyloid fibrils. Thus, two AGE structures, CML and pentosidine, are now recognized in dialysis-related amyloidosis. AGE accumulation in uremia is not accounted for by elevated glucose levels. Since CML and pentosidine formation are closely linked to oxidative processes, we tested the hypothesis that a high oxidative stress enhanced AGE formation in HD patients. We focused on ascorbic acid (AA) because AA is easily oxidized under oxidative stress and its oxidized form (oxiAA) is a source of CML and pentosidine. In vitro incubation of beta2m with AA under atmospheric oxygen resulted in: (1) the rapid appearance of characteristic physicochemical properties of AGEs (brown color, fluorescence, polymerization tendency); (2) the transformation of beta2m into AGE-modified beta2m recognized by a specific monoclonal antibody; and (3) the accelerated formation of CML in beta2m and beta2m-peptide, recognized by mass spectrometry. A similar in vitro incubation of human serum albumin disclosed a parallel production of pentosidine measured by high-performance liquid chromatographic assay. In HD patients, the degree of AA oxidation, assessed as the ratio of oxiAA to total ascorbate, was more than twice as high as that of normal subjects (0.87 +/- 0.16 vs. 0.35 +/- 0.11, P < 0.0001), suggesting the presence of an increased oxidative stress. Interestingly, plasma level of oxiAA was correlated with the plasma levels of protein linked (P < 0.01, r2 = 0.25) and free (P < 0.05, r2 = 0.22) pentosidine. Altogether these results demonstrate that AGE, that is, CML and pentosidine, production is accelerated under oxidative stress, even in the absence of glucose. They suggest that, in uremia, CML and pentosidine production is determined both by an increased oxidative stress and the availability of precursors such as oxiAA. Finally, both CML and pentosidine contribute to the AGEs present in dialysis-related amyloid fibrils.

Generation of a new cystatin C-based estimating equation for glomerular filtration rate by use of 7 assays standardized to the international calibrator

BACKGROUND

Many different cystatin C-based equations exist for estimating glomerular filtration rate. Major reasons for this are the previous lack of an international cystatin C calibrator and the nonequivalence of results from different cystatin C assays.

METHODS

Use of the recently introduced certified reference material, ERM-DA471/IFCC, and further work to achieve high agreement and equivalence of 7 commercially available cystatin C assays allowed a substantial decrease of the CV of the assays, as defined by their performance in an external quality assessment for clinical laboratory investigations. By use of 2 of these assays and a population of 4690 subjects, with large subpopulations of children and Asian and Caucasian adults, with their GFR determined by either renal or plasma inulin clearance or plasma iohexol clearance, we attempted to produce a virtually assay-independent simple cystatin C-based equation for estimation of GFR.

RESULTS

We developed a simple cystatin C-based equation for estimation of GFR comprising only 2 variables, cystatin C concentration and age. No terms for race and sex are required for optimal diagnostic performance. The equation, [Formula: see text] is also biologically oriented, with 1 term for the theoretical renal clearance of small molecules and 1 constant for extrarenal clearance of cystatin C.

CONCLUSIONS

A virtually assay-independent simple cystatin C-based and biologically oriented equation for estimation of GFR, without terms for sex and race, was produced.

GFR estimation using standardized serum cystatin C in Japan

BACKGROUND

Recently, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) developed glomerular filtration rate (GFR)-estimating equations based on standardized serum cystatin C (CKD-EPI(cys)) and standardized serum creatinine plus standardized serum cystatin C (CKD-EPI(cr-cys)). We developed new GFR-estimating equations based on standardized cystatin C for a Japanese population and compared their accuracy with the CKD-EPI equations.

STUDY DESIGN

Accuracy of diagnostic test study.

SETTING & PARTICIPANTS

413 (development data set) and 350 individuals (validation data set).

INDEX TEST

CKD-EPI(cys); CKD-EPI(cr-cys); modifications to CKD-EPI(cys) and CKD-EPI(cr-cys) using Japanese coefficients; and newly developed Japanese eGFR equations based on standardized serum cystatin C (Eq(cys)), cystatin C with a nonrenal factor reflecting hypothesized extrarenal elimination (Eq(cys+nonrenal)), and creatinine in combination with cystatin C (Eq(cr-cys)). Standardized cystatin C values were determined by a colloidal gold immunoassay traceable to the international certified reference material ERM-DA471/IFCC.

REFERENCE TEST

Measured GFR by inulin renal clearance.

RESULTS

In a development data set, we calculated Japanese coefficients for CKD-EPI(cys) and CKD-EPI(cr-cys) of 0.977 (95% CI, 0.853-1.002) and 0.908 (95% CI, 0.889-0.928), respectively. In a validation data set, we compared CKD-EPI(cys), Eq(cys), and Eq(cys+nonrenal) with each other. Bias and accuracy were not significantly different among the 3 equations. The precision of CKD-EPI(cys) was significantly better than for Eq(cys) (P = 0.007) and not significantly different from Eq(cys+nonrenal) (P = 0.6). We then compared 0.908 × CKD-EPI(cr-cys), Eq(cr-cys), and Eq(average) (the average value of Eq(cr) [previous Japanese equation based on standardized serum creatinine] and Eq(cys+nonrenal)) with each other in the validation data set. Bias and accuracy were not significantly different among the 3 equations. The precision of 0.908 × CKD-EPI(cr-cys) was significantly better than for Eq(cr-cys) (P = 0.004) and not significantly different from Eq(average) (P = 0.06).

LIMITATIONS

Limited number of participants with measured GFR >90 mL/min/1.73 m(2). Extrarenal elimination of cystatin C was not measured.

CONCLUSIONS

CKD-EPI(cys) performed well in Japanese individuals, suggesting that equations based on serum cystatin C could be used in patients with different races without modification. Accounting for extrarenal elimination of cystatin C may improve the performance of estimating equations.

Prevalence of chronic kidney disease (CKD) in the Japanese general population predicted by the MDRD equation modified by a Japanese coefficient

BACKGROUND

The number of patients with end-stage renal disease (ESRD) in Japan has continuously increased in the past three decades. In 2005, 36,063 patients whose average age was 66 years entered a new dialysis program. This large number of ESRD patients could be just the tip of the iceberg of an increasing number of patients with chronic kidney disease (CKD). However, to date, a nationwide epidemiological study has not been conducted yet to survey the CKD population.

METHODS

Data for 527,594 (male, 211,034; female, 316,560) participants were obtained from the general adult population aged over 20 years who received annual health check programs in 2000-2004, from seven different prefectures in Japan: Hokkaido, Fukushima, Ibaraki, Tokyo, Osaka, Fukuoka, and Okinawa prefectures. The glomerular filtration rate (GFR) for each participant was estimated from the serum creatinine values, using the abbreviated Modification of Diet in Renal Disease (MDRD) study equation modified by the Japanese coefficient.

RESULTS

The prevalences of CKD stage 3 in the study population, stratified by age groups of 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, and 80-89 years, were 1.4%, 3.6%, 10.8%, 15.9%, 31.8%, 44.0%, and 59.1%, respectively, predicting 19.1 million patients with stage 3 CKD in the Japanese general adult population of 103.2 million in 2004. CKD stage 4 + 5 was predicted in 200,000 patients in the Japanese general adult population. Comorbidity of hypertension, diabetes, and proteinuria increased as the estimated GFR (eGFR) decreased. The prevalence of concurrent CKD was significantly higher in hypertensive and diabetic populations than in the study population overall when CKD was defined as being present with an eGFR of less than 40 ml/min per 1.73 m(2) instead of less than 60 ml/min per 1.73 m(2).

CONCLUSIONS

About 20% of the Japanese adult population (i.e., approximately 19 million people) are predicted to have stage 3 to 5 CKD, as defined by a GFR of less than 60 ml/min per 1.73 m(2).

Estrogen-dependent production of erythropoietin in uterus and its implication in uterine angiogenesis

Although erythropoietin (Epo) has been shown to possess in vitro angiogenic activity, its physiological significance has not been demonstrated. Normally angiogenesis does not occur actively in adults but an exception is the female reproductive organ. In the uterine endometrium, angiogenesis takes place actively for supporting the endometrial growth that occurs during transition from the diestrus to estrous stage. This transition is under control of 17beta-estradiol (E2), an ovarian hormone, and can be mimicked by injection of E2 to ovariectomized (OVX) mouse. Thus, the uterus is a pertinent site to examine the Epo function in angiogenesis. We found that Epo protein and its mRNA were produced in an E2-dependent manner, when the uterus from OVX mouse was cultured in vitro. The de novo protein synthesis was not needed for E2 induction of Epo mRNA. Administration of E2 to OVX mouse induced a rapid and transient increase in Epo mRNA in the uterus. Injection of Epo into the OVX mouse uterine cavity promoted blood vessel formation in the endometrium. Furthermore, injection of the soluble Epo receptor capable of binding with Epo into the uterine cavity of non-OVX mouse in diestrus stage inhibited the endometrial transition to proestrus stage, whereas heat-inactivated soluble Epo receptor allowed the transition to occur. These results, combined with our finding that the endothelial cells in uterine endometrium express Epo receptor, strongly suggest that Epo is an important factor for the E2-dependent cyclical angiogenesis in uterus.

Interstitial vascular rarefaction and reduced VEGF-A expression in human diabetic nephropathy

Diabetic nephropathy (DN) is a frequent complication in patients with diabetes. Although the majority of DN models and human studies have focused on glomeruli, tubulointerstitial damage is a major feature of DN and an important predictor of renal dysfunction. This study sought to investigate molecular markers of pathogenic pathways in the renal interstitium of patients with DN. Microdissected tubulointerstitial compartments from biopsies with established DN and control kidneys were subjected to expression profiling. Analysis of candidate genes, potentially involved in DN on the basis of common hypotheses, identified 49 genes with significantly altered expression levels in established DN in comparison with controls. In contrast to some rodent models, the growth factors vascular endothelial growth factor A (VEGF-A) and epidermal growth factor (EGF) showed a decrease in mRNA expression in DN. This was validated on an independent cohort of patients with DN by real-time reverse transcriptase-PCR. Immunohistochemical staining for VEGF-A and EGF also showed a reduced expression in DN. The decrease of renal VEGF-A expression was associated with a reduction in peritubular capillary densities shown by platelet-endothelial cell adhesion molecule-1/CD31 staining. Furthermore, a significant inverse correlation between VEGF-A and proteinuria, as well as EGF and proteinuria, and a positive correlation between VEGF-A and hypoxia-inducible factor-1alpha mRNA was found. Thus, in human DN, a decrease of VEGF-A, rather than the reported increase as described in some rodent models, may contribute to the progressive disease. These findings and the questions about rodent models in DN raise a note of caution regarding the proposal to inhibit VEGF-A to prevent progression of DN.

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").

HET0016, a potent and selective inhibitor of 20-HETE synthesizing enzyme

The present study examined the inhibitory effects of N-hydroxy-N'-(4-butyl-2-methylphenyl)-formamidine (HET0016) on the renal metabolism of arachidonic acid by cytochrome P450 (CYP) enzymes. HET0016 exhibited a high degree of selectivity in inhibiting the formation of 20-hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE) in rat renal microsomes. The IC(50) value averaged 35+/-4 nM, whereas the IC(50) value for inhibition of the formation of epoxyeicosatrienoic acids by HET0016 averaged 2800+/-300 nM. In human renal microsomes, HET0016 potently inhibited the formation of 20-HETE with an IC(50) value of 8.9+/-2.7 nM. Higher concentrations of HET0016 also inhibited the CYP2C9, CYP2D6 and CYP3A4-catalysed substrates oxidation with IC(50) values of 3300, 83,900 and 71,000 nM. The IC(50) value for HET0016 on cyclo-oxygenase activity was 2300 nM. These results indicate that HET0016 is a potent and selective inhibitor of CYP enzymes responsible for the formation of 20-HETE in man and rat.

A protein kinase C-beta-selective inhibitor ameliorates neural dysfunction in streptozotocin-induced diabetic rats

Increased protein kinase C (PKC) activity has been implicated in the pathogenesis of diabetic retinopathy and nephropathy. However, the role of PKC in diabetic neuropathy remains unclear. The present study was conducted to compare the effect of PKC inhibition by a PKC-beta-selective inhibitor, LY333531 (LY), on diabetic nerve dysfunction with that of an aldose reductase inhibitor, NZ-314 (NZ). Streptozotocin-induced diabetic rats were treated with or without LY and/or NZ for 4 weeks, and motor nerve conduction velocity (MNCV), coefficient of variation of R-R interval (CVR-R), sciatic nerve blood flow (SNBF), peak latencies of oscillatory potentials on electroretinogram, PKC activities in membranous and cytosolic fractions of sciatic nerves, and polyol contents in the tail nerves were measured. Untreated diabetic rats demonstrated delayed MNCV, decreased CVR-R, reduced SNBF, and prolonged peak latencies of oscillatory potentials. Treatment with LY as well as NZ prevented all these deficits in diabetic rats. There were no significant differences in PKC activities in membranous or cytosolic fractions of sciatic nerves between normal and diabetic rats. Treatment with neither LY nor NZ altered PKC activities. Nerve myo-inositol depletion in diabetic rats was ameliorated not only by NZ, but also by LY. These observations suggest that inhibition of PKC-beta by LY may have a beneficial effect in preventing the development of diabetic nerve dysfunction, and that this effect may be mediated through its action on the endoneurial micro-vasculature.

Nucleotide sequence of Escherichia coli K-12 replication origin

From subfragments of an EcoRI fragment (9 kilobase pairs) that contained the replication origin of the Escherichia coli chromosome and had been cloned as a recombinant with a nonreplicating DNA fragment coding for ampicillin resistance, small derivative plasmids were constructed. The smallest of these, pTSO151, contained a segment of 463 base pairs as the chromosomal component. Another plasmid, pSY134, constructed from BamHI digests of the EcoRI fragment and mini-F(pMF21), contained a region of 422 base pairs identical with a corresponding region in pTSO151. We conclude that the replication origin of E. coli chromosome is located within this 422-base-pair segment. The nucleotide sequence of this segment is presented.

Characterization of crustacean hyperglycemic hormone from the crayfish (Procambarus clarkii): multiplicity of molecular forms by stereoinversion and diverse functions

The complete amino acid sequence of two forms of crustacean hyperglycemic hormone (CHH) from the X-organ sinus gland complex of crayfish (Procambarus clarkii) has been determined. There are two variants of P. clarkii CHH (Prc-CHH), I and II, which can be separated by reversed-phase high-performance liquid chromatography (RP-HPLC). Each variant was oxidized by performic acid and then cleaved with lysyl endopeptidase. Intact hormone was also digested with trypsin and endoproteinase Asp-N, successively. The resulting fragments were separated by RP-HPLC and subjected to sequence analyses by a gas-phase sequencer and tandem mass spectrometry. Both variants contain 72 amino acid residues with three disulfide linkages, at positions 7-43, 23-39, and 26-52, and differ from each other by the D/L epimerization of phenylalanine at position 3; Prc-CHH-II contains D-amino acid. Injections of Prc-CHH-I and Prc-CHH-II at a dose of 12.5 pmol resulted in significant increase of hemolymph glucose levels in the crayfish. The hormones are also active in repressing ecdysteroid synthesis at concentrations of 250 mM (Prc-CHH-I) and 25 nM (Prc-CHH-II) in Y-organ culture. These results may indicate that the stereoinversion in the CHH molecule leads to an important alternation in hormonal functions during crustacean development.

Cellular stresses induce the nuclear accumulation of importin alpha and cause a conventional nuclear import block

We report here that importin α accumulates reversibly in the nucleus in response to cellular stresses including UV irradiation, oxidative stress, and heat shock. The nuclear accumulation of importin α appears to be triggered by a collapse in the Ran gradient, resulting in the suppression of the nuclear export of importin α. In addition, nuclear retention and the importin β/Ran-independent import of importin α also facilitate its rapid nuclear accumulation. The findings herein show that the classical nuclear import pathway is down-regulated via the removal of importin α from the cytoplasm in response to stress. Moreover, whereas the nuclear accumulation of heat shock cognate 70 is more sensitive to heat shock than the other stresses, importin α is able to accumulate in the nucleus at all the stress conditions tested. These findings suggest that the stress-induced nuclear accumulation of importin α can be involved in a common physiological response to various stress conditions.

Isolation and structural elucidation of new cyclotetrapeptides, trapoxins A and B, having detransformation activities as antitumor agents

New cyclotetrapeptides, trapoxins A and B were isolated from the culture broth of Helicoma ambiens RF-1023. These compounds exhibit detransformation activities against v-sis oncogene-transformed NIH3T3 cells (sis/NIH3T3) as antitumor agents. The structures were found to be new cyclotetrapeptides, cyclo[(S)-phenylalanyl-(S)-phenylalanyl-(R)-pipecolinyl- (2S,9S)-2-amino-8-oxo-9,10-epoxydecanoyl-] for trapoxin A and cyclo[(S)-phenylalanyl-(S)-phenylalanyl-(R)-prolyl-2- amino-8-oxo-9,10-epoxydecanoyl-] for trapoxin B, by X-ray analysis, mass spectrometric, NMR and chemical studies.

Production of germ line chimera by transfer of primordial germ cells in the domestic chicken (Gallus domesticus)

Blood was collected from Stage 13 to 14 (1) chick embryos. Primordial germ cells (PGCs) were separated from blood cells by Ficoll density gradient centrifugation. One hundred Rhode Island Red PGCs per embryo were transferred to the blood stream of Stage 14 to 15 White Leghorn embryos. Also, one hundred White Leghorn PGCs per embryo were transferred to the blood stream of Stage 14 to 15 Rhode Island Red embryos. Hatched male and female chicks were raised until sexual maturity, and progeny tests were performed by mating these PGC recipients with Rhode Island Red chickens of the opposite sex. Chicks apparently derived from the transferred PGCs, based on the feather color of the chicks, were produced from all 4 possible mating combinations. The present results indicate that the germ line of PGC recipient chickens consists of 2 distinct populations of germ cells.

Production of germline chimeric chickens, with high transmission rate of donor-derived gametes, produced by transfer of primordial germ cells

Germline chimeric chickens were produced by transfer of primordial germ cells from White Leghorn to Barred Plymouth Rock, and vice versa. Blood was collected from stage 13-15 embryos and primordial germ cells were concentrated by Ficoll density gradient centrifugation. Approximately 200 primordial germ cells were injected into the bloodstream through the dorsal aorta of stage 14-15 recipient embryos from which blood had been drawn via the dorsal aorta prior to the injection. Intact embryos were also prepared as recipients for White Leghorns only. The manipulated embryos were cultured in recipient eggshells until hatching. Germline chimerism of the chickens reaching maturity was examined by mating them with Barred Plymouth Rocks and donor-derived offspring were identified based on their feather color. The efficiency of production of germline chimeras was 95% (19/20). When primordial germ cells were transferred from White Leghorn to Barred Plymouth Rock, the average frequency of donor-derived offspring was 81% for three male chimeras (96% for one female chimera), and it was approximately 3.5 times higher for transfer in the opposite direction (23% for 6 male chimeras). Removing blood from recipient embryos prior to primordial germ cell injection enhanced the frequency of donor-derived offspring by 10% in resulting male chimeras. Male chimeras produced donor-derived offspring more frequently (approximately 3.8 times) than female chimeras. Increases, decreases, or no changes were observed in the frequency of donor-derived offspring from the germline chimeras with increasing age.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of new fluorogenic substrates for the rapid and sensitive assay of cathepsin E and cathepsin D

Cathepsin E and cathepsin D are two major intracellular aspartic proteinases implicated in the physiological and pathological degradation of intra- and extracellular proteins. In this study, we designed and constructed highly sensitive synthetic decapeptide substrates for assays of cathepsins E and D based on the known sequence specificities of their cleavage sites. These substrates contain a highly fluorescent (7-methoxycoumarin-4-yl)acetyl (MOCAc) moiety and a quenching 2,4-dinitrophenyl (Dnp) group. When the Phe-Phe bond is cleaved, the fluorescence at an excitation wavelength of 328 nm and emission wavelength of 393 increases due to diminished quenching resulting from the separation of the fluorescent and quenching moieties. The first substrate, MOCAc-Gly-Lys-Pro-Ile-Leu-Phe-Phe-Arg-Le u-Lys(Dnp)gamma-NH2, in which the Lys-Pro combination at positions P5 and P4 was designed for specific interaction with cathepsin E, is hydrolyzed equally well by cathepsins E and D (kcat/Km = 10.9 microM(-1) x s(-1) for cathepsin E and 15.6 microM(-1) x s(-1) for cathepsin D). A very acidic pH optimum o was obtained for both enzymes. The second substrate, MOCAc-Gly-Lys-Pro-Ile-Ile-Phe-Phe-Arg-Le u-Lys(Dnp)gamma-NH2, in which the isoleucine residue at position P2 was meant to increase the specificity for cathepsin E, is also hydrolyzed equally by both enzymes (kcat/Km = 12.2 microM(-1) x s(-1) for cathepsin E and 16.3 microM(-1) x s(-1) for cathepsin D). The kcat/Km values for both substrates are greater than those for the best substrates for cathepsins E and D described so far. Unfortunately, each substrate shows little discrimination between cathepsin E and cathepsin D, suggesting that amino acids at positions far from the cleavage site are important for discrimination between the two enzymes. However, in combination with aspartic proteinase inhibitors, such as pepstatin A and Ascaris pepsin inhibitor, these substrates enable a rapid and sensitive determination of the precise levels of cathepsins E and D in crude cell extracts of various tissues and cells. Thus these substrates represent a potentially valuable tool for routine assays and for mechanistic studies on cathepsins E and D.