Polar vasculosis is associated with better kidney outcome in type 2 diabetes with biopsy-proven diabetic kidney disease: A multicenter cohort study

AIMS/INTRODUCTION

This multicenter cohort study retrospectively assessed the association between polar vasculosis and the progression of diabetic kidney disease (DKD) in type 2 diabetes.

MATERIALS AND METHODS

We enrolled 811 patients with type 2 diabetes, biopsy-proven DKD, and proteinuria (≥0.15 g/g creatinine [g/day]). The association between polar vasculosis and other kidney lesions was explored. The outcome was DKD progression defined as a composite of renal replacement therapy initiation or 50% decline in estimated glomerular filtration rate (eGFR) from baseline.

RESULTS

Of the 811 cases, 677 (83.5%) had polar vasculosis. In multivariate logistic regression analysis, subendothelial widening of the glomerular basement membrane, glomerulomegaly, glomerular class in the Renal Pathology Society classification ≥IIb, vascular lesions, age, eGFR, and hemoglobin A1c were positively associated with polar vasculosis, whereas interstitial fibrosis and tubular atrophy (IFTA) was negatively associated with polar vasculosis. During a median follow-up of 5.2 years, progression of DKD occurred in 322 of 677 (7.4 events/100 person-years) and 79 of 134 (11.4 events/100 person-years) cases with and without polar vasculosis, respectively. Kaplan-Meier analysis showed that polar vasculosis was associated with lower cumulative incidences of DKD progression. Multivariate Cox regression analyses showed that polar vasculosis was associated with a lower risk of DKD progression, regardless of eGFR or proteinuria subgroups. These associations between polar vasculosis and better kidney outcome were unchanged considering all-cause mortality before DKD progression as a competing event.

CONCLUSIONS

This study showed that polar vasculosis of DKD was associated with less advanced IFTA and a better kidney outcome in type 2 diabetes with proteinuria.

Tracing all patients who received insured dialysis treatment in Japan and the present situation of their number of deaths

Background

The survival rate of chronic dialysis patients in Japan remains the highest worldwide, so there is value in presenting Japan’s situation internationally. We examined whether aggregate figures on dialysis patients in the National Database of Health Insurance Claims and Special Health Checkups of Japan (NDB), which contains data on insured procedures of approximately 100 million Japanese residents, complement corresponding figures in the Japanese Society for Dialysis Therapy Renal Data Registry (JRDR).

Methods

Subjects were patients with medical fee points for dialysis recorded in the NDB during 2014–2018. We analyzed annual numbers of dialysis cases, newly initiated dialysis cases– and deaths.

Results

Compared with the JRDR, the NDB had about 6–7% fewer dialysis cases but a similar number of newly initiated dialysis cases. In the NDB, the number of deaths was about 6–10% lower, and the number of hemodialysis cases was lower, while that of peritoneal dialysis cases was higher. The cumulative survival rate at dialysis initiation was approximately 6 percentage points lower in the NDB than in the JRDR, indicating that some patients die at dialysis initiation. Cumulative survival rate by age group was roughly the same between the NDB and JRDR in both sexes.

Conclusion

The use of the NDB enabled us to aggregate data of dialysis patients. With the definition of dialysis patients used in this study, analyses of concomitant medications, comorbidities, surgeries, and therapies will become possible, which will be useful in many future studies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10157-021-02163-z.

Two-year longitudinal trajectory patterns of albuminuria and subsequent rates of end-stage kidney disease and all-cause death: a nationwide cohort study of biopsy-proven diabetic kidney disease

INTRODUCTION

Data on the association between longitudinal trajectory patterns of albuminuria and subsequent end-stage kidney disease (ESKD) and all-cause mortality in diabetic kidney disease (DKD) are sparse.

RESEARCH DESIGN AND METHODS

Drawing on nationally representative data of 329 patients with biopsy-proven DKD and an estimated glomerular filtration rate above 30 mL/min/1.73 m² at the time of biopsy, we used joint latent class mixed models to identify different 2-year trajectory patterns of urine albumin to creatinine ratio (UACR) and assessed subsequent rates of competing events: ESKD and all-cause death.

RESULTS

A total of three trajectory groups of UACR were identified: 'high-increasing' group (n=254; 77.2%), 'high-decreasing' group (n=24; 7.3%), and 'low-stable' group (n=51; 15.5%). The 'low-stable' group had the most favorable risk profile, including the baseline UACR (median (IQR) UACR (mg/g creatinine): 'low-stable', 109 (50-138); 'high-decreasing', 906 (468-1740); 'high-increasing', 1380 (654-2502)), and had the least subsequent risk of ESKD and all-cause death among the groups. Although there were no differences in baseline characteristics between the 'high-decreasing' group and the 'high-increasing' group, the 'high-decreasing' group had better control over blood pressure, blood glucose, and total cholesterol levels during the first 2 years of follow-up, and the incidence rates of subsequent ESKD and all-cause death were lower in the 'high-decreasing' group compared with the 'high-increasing' group (incidence rate of ESKD (per 1000 person-years): 32.7 vs 77.4, p=0.014; incidence rate of all-cause death (per 1000 person-years): 0.0 vs 25.4, p=0.007).

CONCLUSIONS

Dynamic changes in albuminuria are associated with subsequent ESKD and all-cause mortality in DKD. Reduction in albuminuria by improving risk profile may decrease the risk of ESKD and all-cause death.

Serum hemoglobin concentration, as a reflection of renal fibrosis, and risk of renal decline in early-stages of diabetic kidney disease: a nationwide, biopsy-based cohort study

BACKGROUND

Prognosticating disease progression in patients with diabetic kidney disease (DKD) is challenging, especially in the early stages of kidney disease. Anemia can occur in the early stages of kidney disease in diabetes. We therefore postulated that serum hemoglobin concentration, as a reflection of incipient renal tubulointerstitial impairment, can be used as a marker to predict DKD progression.

METHODS

Drawing on nationally representative data of patients with biopsy-proven DKD, 246 patients who had an estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 at renal biopsy were identified: aged 56 (45, 63); 62.6% men; Hb 13.3 (12.0, 14.5) g/dL; eGFR 76.2 (66.6, 88.6) mL/min/1.73 m2; urine albumin-to-creatinine ratio [UACR] 534 (100, 1480) mg/g Crea. Serum hemoglobin concentration were divided into quartiles: ≤12, 12.1-13.3, 13.4-14.5, and ≥14.6 g/dL. The association between serum hemoglobin concentration and the severity of renal pathological lesions was explored. A multivariable Cox regression model was used to estimate the risk of DKD progression (new onset of end-stage kidney disease, 50% reduction of eGFR, or doubling of serum creatinine). The incremental prognostic value of DKD progression by adding serum hemoglobin concentration to the known risk factors of DKD was assessed.

RESULTS

Serum hemoglobin levels negatively correlated with all renal pathological features, especially with the severity of interstitial fibrosis (ρ =-0.52; P < 0.001). During a median follow-up of 4.1 years, 95 developed DKD progression. Adjusting for known risk factors of DKD progression, the hazard ratio in the first, second, and third quartile (the fourth quartile as a reference) were 2.74 (95% CI 1.26-5.97), 2.33 (95% CI 1.07-5.75), and 1.46 (95% CI 0.71-3.64), respectively. Addition of the serum hemoglobin concentration to the known risk factors of DKD progression improved the prognostic value of DKD progression (the global chi-statistics increased from 55.1 to 60.8; P < 0.001).

CONCLUSIONS

Serum hemoglobin concentration, which reflects incipient renal fibrosis, can be useful for predicting DKD progression in the early stages of kidney disease.

Renal arteriolar hyalinosis, not intimal thickening in large arteries, is associated with cardiovascular events in people with biopsy-proven diabetic nephropathy

AIMS

Diabetic nephropathy, a pathologically diagnosed microvascular complication of diabetes, is a strong risk factor for cardiovascular events, which mainly involve arteries larger than those affected in diabetic nephropathy. However, the association between diabetic nephropathy pathological findings and cardiovascular events has not been well studied. We aimed to investigate whether the pathological findings in diabetic nephropathy are closely associated with cardiovascular event development.

METHODS

This retrospective cohort study analysed 377 people with type 2 diabetes and biopsy-proven diabetic nephropathy, with a median follow-up of 5.9 years (interquartile range 2.0 to 13.5). We investigated how cardiovascular events were impacted by two vascular diabetic nephropathy lesions, namely arteriolar hyalinosis and arterial intimal thickening, and by glomerular and interstitial lesions.

RESULTS

Of the 377 people with diabetic nephropathy, 331 (88%) and 295 (78%) had arteriolar hyalinosis and arterial intimal thickening, respectively. During the entire follow-up period, those with arteriolar hyalinosis had higher cardiovascular event rates in the crude Kaplan-Meier analysis than those without these lesions (P = 0.005, log-rank test). When fully adjusted for clinically relevant confounders, arteriolar hyalinosis independently predicted cardiovascular events [hazard ratio (HR) 1.99; 95% confidence interval (CI) 1.12, 3.86], but we did not find any relationship between arterial intimal thickening and cardiovascular events (HR 0.89; 95% CI 0.60, 1.37). Additionally, neither glomerular nor interstitial lesions were independently associated with cardiovascular events in the fully adjusted model.

CONCLUSIONS

Arteriolar hyalinosis, but not intimal thickening of large arteries, was strongly associated with cardiovascular events in people with diabetic nephropathy.

Relationship between initial peritoneal dialysis modality and risk of peritonitis

Peritonitis is a critical complication of peritoneal dialysis (PD). Investigators have reported the risk of peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD) versus automated peritoneal dialysis (APD), but the available evidence is predominantly based on observational studies which failed to report on the connection type. Our understanding of the relationship between peritonitis risk and PD modality thus remained insufficient. We studied 285 participants who began PD treatment between 1997 and 2014 at three hospitals in Nara Prefecture in Japan. We matched 106 APD patients with 106 CAPD patients based on their propensity scores. The primary outcome was time to first episode of peritonitis within 3 years after PD commencement. In total, PD peritonitis occurred in 64 patients during the study period. Patients initiated on APD had a lower risk of peritonitis than did those initiated on CAPD in both the unadjusted and adjusted models. The hazard ratio (HR) and 95% confidence interval (CI) for the primary endpoint were 0.30 (0.17–0.53) in the fully adjusted model including connection type. In the matched cohort, APD patients had a significantly lower risk of peritonitis than did CAPD patients (log-rank: p < 0.001, HR 0.32, 95% CI 0.16–0.59). The weighting-adjusted analysis of the inverse probability of treatment yielded a similar result (HR 0.35, 95% CI 0.18–0.67). In conclusion, patients initiated on APD at PD commencement had a reduced risk of peritonitis compared with those initiated on CAPD, suggesting APD may be preferable for prevention of peritonitis among PD patients.

Clinicopathological features of fast eGFR decliners among patients with diabetic nephropathy

INTRODUCTION

The speed of declining kidney function differs among patients with diabetic nephropathy. This study was undertaken to clarify clinical and pathological features that affect the speed of declining kidney function in patients with diabetic nephropathy.

RESEARCH DESIGN AND METHODS

This study was design as multicenter retrospective study. The subjects (377 patients with diabetic nephropathy diagnosed by kidney biopsy at 13 centers in Japan) were classified into three groups based on the estimated glomerular filtration rate (eGFR) declining speed. The eGFR increasing group, the control group, and the eGFR declining group were divided at 0 and 5 mL/min/1.73 m²/year, respectively. Characteristics of clinicopathological findings of declining kidney function were evaluated.

RESULTS

The mean observation period of this study was 6.9 years. The control group, the eGFR increasing group, and the eGFR declining group included 81, 66, and 230 patients, respectively. The incidences of composite kidney events represented by 100 persons/year were 25.8 in the eGFR declining group and 2.0 in the eGFR increasing group. After adjustment for age, sex, systolic blood pressure, hemoglobin, and urinary albumin levels, three clinicopathological findings (urinary albumin levels, presence of nodular lesion, and mesangiolysis) were risk factors for inclusion in the eGFR declining group (the ORs were 1.49, 2.18, and 2.08, respectively). In contrast, the presence of subendothelial space widening and polar vasculosis were characteristic findings for inclusion in the eGFR increasing group (the ORs were 0.53 and 0.41, respectively).

CONCLUSIONS

As well as urinary albumin elevation, nodular lesion and mesangiolysis were characteristic pathological features of patients with fast declining kidney function.

Peritonitis due to Moraxella osloensis: A case report and literature review

A-26-year-old man was admitted to our hospital with diffuse abdominal pain, nausea, and vomiting. He had a history of malignant nephrosclerosis, for which he had been receiving peritoneal dialysis (PD) for the past 14 months. His PD effluent was cloudy and turbid (white blood cell count, 10,528/μL; neutrophils 95.2%). A Gram-negative coccobacillus was isolated from peritoneal fluid culture. However, the organism could not be identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) (Vitek MS, bioMérieux), but was identified as Moraxella osloensis by the 16S rRNA gene sequencing. He was successfully treated with intraperitoneal cefazolin therapy for 3 weeks without removing the intra-abdominal catheter. A literature review revealed three previous case reports all of which were diagnosed by MALDI Biotyper (Bruker Daltonics), suggesting that the identification of M. osloensis may vary depending on the type of MALDI-TOF MS system. In conclusion, we experienced a case of M. osloensis infection in a PD patient, which was successfully treated by antibiotic treatment, without removing the PD catheter.

Nonproteinuric Versus Proteinuric Phenotypes in Diabetic Kidney Disease: A Propensity Score-Matched Analysis of a Nationwide, Biopsy-Based Cohort Study

OBJECTIVE

Clinicopathological characteristics, renal prognosis, and mortality in patients with type 2 diabetes and reduced renal function without overt proteinuria are scarce.

RESEARCH DESIGN AND METHODS

We retrospectively assessed 526 patients with type 2 diabetes and reduced renal function (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m²), who underwent clinical renal biopsy and had follow-up data, from Japan's nationwide multicenter renal biopsy registry. For comparative analyses, we derived one-to-two cohorts of those without proteinuria versus those with proteinuria using propensity score-matching methods addressing the imbalances of age, sex, diabetes duration, and baseline eGFR. The primary end point was progression of chronic kidney disease (CKD) defined as new-onset end-stage renal disease, decrease of eGFR by ≥50%, or doubling of serum creatinine. The secondary end point was all-cause mortality.

RESULTS

Eighty-two patients with nonproteinuria (urine albumin-to-creatinine ratio [UACR] <300 mg/g) had lower systolic blood pressure and less severe pathological lesions compared with 164 propensity score-matched patients with proteinuria (UACR ≥300 mg/g). After a median follow-up of 1.9 years (interquartile range 0.9-5.0 years) from the date of renal biopsy, the 5-year CKD progression-free survival was 86.6% (95% CI 72.5-93.8) for the nonproteinuric group and 30.3% (95% CI 22.4-38.6) for the proteinuric group (log-rank test P < 0.001). The lower renal risk was consistent across all subgroup analyses. The all-cause mortality was also lower in the nonproteinuric group (log-rank test P = 0.005).

CONCLUSIONS

Patients with nonproteinuric diabetic kidney disease had better-controlled blood pressure and fewer typical morphological changes and were at lower risk of CKD progression and all-cause mortality.

Effect of Aspirin on Cancer Chemoprevention in Japanese Patients With Type 2 Diabetes: 10-Year Observational Follow-up of a Randomized Controlled Trial

OBJECTIVE

This study analyzed the efficacy of low-dose aspirin in cancer chemoprevention in patients with diabetes.

RESEARCH DESIGN AND METHODS

This study was a posttrial follow-up of the Japanese Primary Prevention of Atherosclerosis with Aspirin for Diabetes (JPAD) trial. Participants in the JPAD trial (2,536 Japanese patients with type 2 diabetes and without preexisting cardiovascular disease) were randomly allocated to receive aspirin (81 or 100 mg daily) or no aspirin. After that trial ended in 2008, we followed up with the participants until 2015, with no attempt to change the previously assigned therapy. The primary end point was total cancer incidence. We investigated the effect of low-dose aspirin on cancer incidence.

RESULTS

During the median follow-up period of 10.7 years, a total of 318 cancers occurred. The cancer incidence was not significantly different between the aspirin and no-aspirin groups (log-rank, P = 0.4; hazard ratio [HR], 0.92; 95% CI, 0.73-1.14; P = 0.4). In subgroup analyses, aspirin did not affect cancer incidence in men, women, or participants aged ≥65 years. However, it decreased cancer incidence in participants aged <65 years (log-rank, P = 0.05; HR, 0.67; 95% CI, 0.44-0.99; P = 0.048). After adjusting for sex, hemoglobin A_1c, smoking status, and administration of metformin and statins, aspirin significantly reduced cancer incidence in participants aged <65 years (adjusted HR, 0.66; 95% CI, 0.43-0.99; P = 0.04).

CONCLUSIONS

Low-dose aspirin did not reduce cancer incidence in Japanese patients with type 2 diabetes.

Unforeseen renal pathological findings in a patient with type 2 cardiorenal syndrome who died after 4 years of continuous ambulatory peritoneal dialysis

A man in his 30s with dilated cardiomyopathy was admitted to our hospital with heart failure exacerbation. Despite optimal medical treatment, his renal function progressively declined to end-stage renal failure. Type 2 cardiorenal syndrome (CRS) was diagnosed and continuous ambulatory peritoneal dialysis was started. He died of a brainstem infarction 4 years later. Postmortem renal pathology revealed no significant changes in the glomeruli except for shrinkage, normal arterioles and focal degeneration of the tubules with peritubular fibrosis. This suggests that renal replacement therapy can be withdrawn from some patients with type 2 CRS.

Heart Failure Associated with Metastatic Myocardial Calcification in a Hemodialysis Patient with Progressive Calcification of the Hand

Metastatic myocardial calcification is a frequent cause of heart failure in hemodialysis patients. However, early detection is difficult, often resulting in a poor prognosis. A 47-year-old man with hemodialysis-dependent end-stage renal disease presented with progressive dyspnea. Levels of serum phosphate, calcium, and intact parathyroid hormone were poorly controlled. He developed pain in his right thumb 1 year before presentation, and the pain gradually increased and extended to the entire right hand. Hand radiography 1 month earlier had revealed significant progressive calcification. Echocardiography showed severe, diffuse hypokinesis and pericardial effusion as well as possible anterior myocardial calcification with high echogenicity. Chest computed tomography revealed a severely dilated heart with anterior massive myocardial calcification and a large amount of pericardial effusion, which was not detected on computed tomography performed 20 months earlier. The patient was diagnosed with heart failure associated with metastatic myocardial calcification and died suddenly 2 weeks later. This experience suggests that progressive metastatic calcification of the skin and subcutaneous tissue is useful for predicting myocardial calcification.

[Anti-MuSK antibody-positive myasthenia gravis with nephrotic syndrome: a case report]

A 40-year-old man was admitted to our hospital because of dysarthria, difficulty swallowing, double vision and weakness of both upper extremities. There were no detectable anti-AChR antibodies. He was diagnosed with seronegative myasthenia gravis (SNMG) based on a positive edrophonium test and positive waning on repetitive stimulation. Thereafter serological examination detected anti-muscle-specific kinase (MuSK) antibodies and he was diagnosed with anti-MuSK antibody-positive MG. Three years after the onset, the patient developed rapidly progressing respiratory failure and fever. He was diagnosed with aspiration pneumonia caused by swallowing difficulty. He was treated with mechanical ventilation, plasma exchange and antibiotics. Laboratory tests on admission also demonstrated nephrotic syndrome. Renal biopsy specimens showed diffuse thickening of the basement membrane by PAS and PAM stain, and granular immunofluorescent deposits of IgG4 along the glomerular capillary walls. Therefore, he was also diagnosed with membranous nephropathy in addition to anti-MuSK antibody-positive MG. MG is sometimes complicated with nephrotic syndrome, however there has been no report of anti-MuSK-antibody positive MG complicated with nephrotic syndrome. It has been reported that anti-MuSK-antibodies are IgG4 and that membranous nephropathy is suggested to be an IgG4 mediated disease. Our findings suggest that IgG4 may play an important role in the pathogenesis of our patient.

[Case of anti-glomerular basement membrane antibody nephritis in a patient who was able to withdraw from dialysis and gave birth twice but underwent living renal transplantation due to progression to end-stage renal failure 15 years after onset]

A 34-year-old woman with suspected rapidly progressive glomerulonephritis had been admitted to our hospital in March 1993 at the age of 19 years. Renal biopsy revealed cellular crescent formation in 24 of 26 glomeruli. Serum examination was positive for anti-glomerular basement membrane (GBM) antibody, while pulmonary hemorrhage was absent. Based on these findings, she was diagnosed with anti-GBM antibody nephritis, and treated with corticosteroid pulse therapy and double filtration plasmapheresis (DFPP) in addition to hemodialysis (HD). HD was withdrawn within 2 months. Wishing to have a baby, she had delivery in 1997 and 2000. Subsequently, her renal function gradually decreased, and she underwent an ABO-incompatible living-donor kidney transplant, with her husband as the donor, in March 2008. She has been making good progress after transplantation. Anti-GBM antibody nephritis has a poor prognosis, but renal function was maintained for 15 years in this patient, who responded well to the initial treatment. The underlying disease rarely recurs if transplantation is performed after the patient has become negative for anti-GBM antibody, anti-GBM antibody nephritis therefore seems to be a good indication for treating patients with renal transplantation.

Microbiological and chemical quality of ground beef treated with sodium lactate and sodium chloride during refrigerated storage

The effects of sodium lactate (NaL) and sodium chloride (NaCl), either alone (30 g/kg) or in combination (20+20 g/kg), on the microbiological and chemical quality of raw ground beef during vacuum-packaged storage at 2 degrees C were investigated. The results showed that addition of NaL alone or in combination with NaCl significantly delayed the proliferation of aerobic plate counts, psychrotrophic counts, lactic acid bacteria and Enterobacteriaceae and extended the shelf life of the product up to 15 and 21 days, respectively, versus 8 days only for control. Over the storage time (21 days), NaL maintained the ground beef at almost constant pH, while the pH of control or NaCl-treated samples significantly decreased. Lipid oxidation (TBA value) was not affected by addition of NaL. At storage day 21 however, TBA values of both NaL-treated (0.309) and control (0.318) samples were significantly lower than those of samples treated with NaCl (0.463). The combination of NaCl with NaL significantly reduced the oxidative changes caused by NaCl (0.384 versus 0.463). Therefore, NaL alone or in combination with NaCl could be utilized successfully to reduce the microbial growth, maintain the chemical quality, and extend the shelf life of ground beef during refrigerated storage.

Antioxidant and antimicrobial effects of garlic in chicken sausage

The antioxidant and antimicrobial effects of equivalent concentrations of fresh garlic (FG), garlic powder (GP) and garlic oil (GO) were investigated against lipid oxidation and microbial growth in raw chicken sausage during storage at 3 degrees C. The antioxidant activities were compared to that of a standard synthetic antioxidant; butylated hydroxyanisole (BHA). The initial mean levels of thiobarbituric acid (TBA) value and peroxide value (POV) were 0.140 and 6.32, respectively. However after 21 days of storage, TBA and POV ranged from 0.151 to 4.92, respectively, in FG (50 g/kg) formulated samples to 0.214 and 8.64, respectively, in GO (0.06 g/ kg) formulation. Addition of either garlic or BHA (0.1 g/kg) significantly delayed lipid oxidation when compared with control. The antioxidant activities of the various materials added followed the order FG>GP>BHA>GO. On the other hand, the initial aerobic plate count (APC) in the samples was 4.41 log(10) CFU/g. Addition of FG (30 g/kg) or GP (9 g/kg) significantly reduced the APC and, subsequently, the shelf-life of the product was extended to 21 days. However, addition of GO or BHA resulted in no significant difference in APC when compared with control. Sensory analysis indicated that FG had a significant stronger flavor than the other sausage formulations. The results suggest that fresh garlic and garlic powder, through their combined antioxidant and antimicrobial effects, are potentially useful in preserving meat products.

In vitro effects of Habu snake venom on cultured mesangial cells

BACKGROUND

Habu snake venom (HSV)-induced glomerulonephritis is a unique model showing a progressive course of mesangial proliferation. To elucidate the in vitro effects of HSV, we examined whether HSV itself could have direct effects on the cultured mesangial cells, such as cell proliferation and activation of chemokine gene expression.

METHODS

The incorporation of 5-[(125)I]iodo-2'-deoxyuridine was measured with a gamma-counter, and gene expressions of growth factors, chemokines and cytokines were evaluated by a real time quantitative PCR.

RESULTS

We demonstrated that excessive or continuous HSV stimulation decreased a mesangial cell viability. However, adequate and temporary HSV stimulation induced proliferation of mesangial cells in vitro along with a significant elevation of monocyte chemoattractant protein-1 (MCP-1) mRNA levels. In addition to these in vitro results, we showed that MCP-1 mRNA levels increased in renal cortices of glomerulonephritis induced by HSV. Immunohistochemistry also showed a positive staining for MCP-1 in the marginal area of glomerulus with mesangiolysis.

CONCLUSIONS

These data suggest that HSV itself may elicit direct biological effects on mesangial cells which may participate in pathophysiology of glomerulonephritis induced by HSV.

Levels of MCP-1 and GM-CSF mRNA correlated with inflammatory cytokines mRNA levels in experimental autoimmune myocarditis in rats

Infiltration of monocytes and T cells is known to be an essential trigger for the progression of experimental autoimmune myocarditis (EAM) in rats. Monocyte chemotactic protein-1 (MCP-1) and granulocyte-macrophage colony-stimulating factor (GM-CSF) were shown to mediate the migration of monocytes and T cells into inflammatory sites and to proliferate monocytes. Thus, we evaluated levels of MCP-1 and GM-CSF mRNA in the myocardium of EAM in rats using a real time quantitative PCR method. We also examined the correlation of MCP-1 or GM-CSF mRNA levels with those of inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) in the same lesion. Levels of MCP-1, GM-CSF, TNF-alpha, IL-1beta and IL-6 mRNA increased with the progression of myocarditis which was accompanied by the accumulation of ED-1 positive cells. The MCP-1 and GM-CSF mRNA levels were positively correlated with TNF-alpha, IL-1beta and IL-6 mRNA levels in the same lesion of EAM. We also demonstrated that serum MCP-1 concentrations were increased during the active stage of EAM, and were correlated with MCP-1 mRNA levels in the myocardium of each rat. These findings suggest that elevated MCP-1 and GM-CSF may associate with the migration and proliferation of monocytes/macrophages in EAM. Thus, MCP-1 and GM-CSF may play an important role in the progression of EAM.

CAD/DFF40 nuclease is dispensable for high molecular weight DNA cleavage and stage I chromatin condensation in apoptosis

DNA degradation during apoptotic execution generally occurs at two levels: early as high molecular weight (HMW) fragments and later on as oligonucleosomal fragments. Two nucleases, CAD/CPAN/DFF40 and endonuclease G, can digest nuclear chromatin to produce the oligonucleosomal fragments, and it has been suggested that CAD might be responsible for HMW DNA cleavage. To more clearly define the role of CAD in nuclear disassembly, we have generated CAD(-/-) sublines of chicken DT40 cells in which the entire CAD open reading frame has been deleted. These cells grow normally and undergo apoptosis with kinetics essentially identical to wild type cells. However, they fail to undergo detectable oligonucleosomal fragmentation, proving that CAD is essential for this stage of DNA cleavage, at least in DT40 cells. Other aspects of nuclear disassembly, including HMW DNA cleavage and early stage apoptotic chromatin condensation against the nuclear periphery proceed normally in the absence of CAD. However, the final stages of chromatin condensation and nuclear fragmentation do not occur. Our results demonstrate that CAD is required for complete disassembly of the nucleus during apoptosis and reveal the existence of one or more as yet unidentified second factors responsible for HMW DNA cleavage and the early stages of apoptotic chromatin condensation.

Polyamines of the thermophilic eubacteria belonging to the genera Thermosipho, Thermaerobacter and Caldicellulosiruptor

Cellular polyamines of four new thermophiles located in three early branched eubacterial clades, were investigated for the chemotaxonomic significance of polyamine distribution profiles. The thermophilic anaerobic Thermosipho japonicus, belonging to the order Thermotogales, contained norspermidine, norspermine and thermospermine in addition to spermidine and spermine. The polyamine profile was identical to the polyamine composition of Thermotoga, Fervidobacterium and Petrotoga species of the order. Spermidine, norspermidine, spermine, N4-bis(aminopropyl)spermidine and agmatine were found in thermophilic aerobic Thermaerobacter marianensis. Some differences were observed in the polyamine compositions of the phylogenetically related thermophilic anaerobes, Moorella, Dictyoglomus, Thermoanaerobacterium and Thermoanaerobacter species. Thermophilic anaerobic Caldicellulosiruptor kristianssonii and Caldicellulosiruptor owensensis contained a linear penta-amine, thermopentamine, and two quaternary branched penta-amines, N4-bis(aminopropyl)spermidine and N4-bis(aminopropyl)norspermidine, as the major polyamines. A novel tertiary branched penta-amine, N4-aminopropylspermine, was found in the two Caldicellulosiruptor species.

Improved data processing for optical imaging of developing neuronal connectivity in the neonatal mouse barrel cortex

Optical recording methods using voltage-sensitive dyes have proven valuable for the analysis of neuronal networks both in vivo and in vitro. This technique detects membrane potential changes as changes in the absorption or fluorescence of voltage-sensitive dyes incorporated into the cellular plasma membranes. The reliability of the optical recording technique is dependent on the dye-related response being fast enough to follow the electrical activity and of the response being more or less proportional to the amplitude of the membrane potential change. A high spatial resolution can be achieved using an appropriate imaging system and a dye with a response of sufficiently high signal-to-noise ratio. Thus, it is now anticipated that this method will be able to shed more light on the spatio-temporal information processing of neocortical circuitry. While the FUJIX HR Deltaron 1700 optical imaging system offers a reasonably high time (0.6 ms) and space-resolution (7 microm at 10x magnification), one drawback of this system, however, is its relatively poor data processing capabilities. We have therefore developed a protocol to improve the signal-to-noise ratio by modifying the calculation algorithm of the optical data. Consequently, we characterized optical responses in thalamocortical slices to find developmental landmarks of thalamocortical and intracortical connectivity in the neonatal mouse barrel cortex. Successful application of this method has been published on the analysis of thalamocortical glutamatergic connectivity [8].

Detection of DNA cleavage in apoptotic cells

At least two discrete deoxyribonuclease activities can be detected during apoptotic death, one that generates 30- to 500-kilobase pair (kbp) domain-sized fragments and another that mediates internucleosomal DNA degradation. The latter nuclease has been identified as the caspase-activated deoxyribonuclease (CAD)/CPAN, a unique enzyme that is normally inhibited by the regulatory subunit ICAD (inhibitor of CAD)/DFF45 (DNA fragmentation factor). In this chapter, techniques widely used to detect DNA cleavage in apoptotic cells, including pulsed-field gel electrophoresis, conventional agarose gel electrophoresis, and terminal transferase-mediated dUTP nick end-labeling (TUNEL), are briefly reviewed. In addition, the use of ICAD to inhibit apoptosis-associated nuclease activity is illustrated. When properly applied, these techniques are widely applicable to the characterization of apoptotic cells.

Measurements of macromolecule-bound and ultra-filtrable polyamines in rat liver homogenized without buffer

Ultra-filtrable and macromolecule-bound polyamines in rat liver homogenates, made without buffer, were determined, using Potter-Elvehjem homogenizer and commercially available, pressure-aided ultrafiltration device with a membrane pore size that allows passage of particles of molecular weight no larger than 5000. About 90% of polyamines in the liver were shown to be equilibrated with externally added 15N-labeled polyamines, based on the difference in the ratio of the natural to 15N-labeled polyamine in the liver homogenate and the ultrafiltrate. The entire amount of ultrafiltrate in the homogenized liver, required for calculation of the amounts of ultra-filtrable and macromolecule-bound polyamines, was estimated to be about 0.25 g in one gram of the homogenate, using a limited dilution curve of spermine in the ultrafiltrate with phosphate buffered saline and distilled water. With this value, ultra-filtrable polyamines in normal rat liver homogenate were calculated as about 25%, 8%, and 2% of the total amount of putrescine, spermidine, and spermine, respectively. The method was then used to measure ultra-filtrable and macromolecule-bound polyamines in regenerating rat liver homogenates, to examine possible changes of polyamines during cell growth. The method was also applied to measure other ultra-filtrable compounds such as amino acids and inorganic ions in rat liver homogenate.

Two distinct pathways leading to nuclear apoptosis

Apaf-1(-/-) or caspase-3(-/-) cells treated with a variety of apoptosis inducers manifest apoptosis-associated alterations including the translocation of apoptosis-inducing factor (AIF) from mitochondria to nuclei, large scale DNA fragmentation, and initial chromatin condensation (stage I). However, when compared with normal control cells, Apaf-1(-/-) or caspase-3(-/-) cells fail to exhibit oligonucleosomal chromatin digestion and a more advanced pattern of chromatin condensation (stage II). Microinjection of such cells with recombinant AIF only causes peripheral chromatin condensation (stage I), whereas microinjection with activated caspase-3 or its downstream target caspase-activated DNAse (CAD) causes a more pronounced type of chromatin condensation (stage II). Similarly, when added to purified HeLa nuclei, AIF causes stage I chromatin condensation and large-scale DNA fragmentation, whereas CAD induces stage II chromatin condensation and oligonucleosomal DNA degradation. Furthermore, in a cell-free system, concomitant neutralization of AIF and CAD is required to suppress the nuclear DNA loss caused by cytoplasmic extracts from apoptotic wild-type cells. In contrast, AIF depletion alone suffices to suppress the nuclear DNA loss contained in extracts from apoptotic Apaf-1(-/-) or caspase-3(-/-) cells. As a result, at least two redundant parallel pathways may lead to chromatin processing during apoptosis. One of these pathways involves Apaf-1 and caspases, as well as CAD, and leads to oligonucleosomal DNA fragmentation and advanced chromatin condensation. The other pathway, which is caspase-independent, involves AIF and leads to large-scale DNA fragmentation and peripheral chromatin condensation.

Regulation of both apoptosis and cell survival by the v-Src oncoprotein

A number of oncogenes alter the regulation of the cell cycle and cell death, contributing to the altered growth of tumours. Expression of the v-Src oncoprotein in Rat-1 fibroblasts prevented cell cycle exit in response to growth factor withdrawal. Here we investigated whether survival of v-Src transformed cells in low serum is dependent on v-Src activity. We used a temperature sensitive v-Src to study the effect inactivating v-Src on transformed cells growing under low serum conditions. We found when we switched off v-Src the cells died by apoptosis characterised by activation of caspases and the stress-activated kinases, JNK (Jun N-terminal kinase) and p38 MAP (mitogen activated protein) kinase. We were able to prevent cell death by addition of serum or overexpression of Bcl-2. Thus v-Src transformed Rat-1 cells can be protected from apoptosis by serum, v-Src, or Bcl-2. We investigated how v-Src protects from apoptosis under these conditions. Amongst other effects, v-Src activates two kinases which have been shown to protect cells from apoptosis, phosphatidylinositol 3-kinase (PI3-K) and extracellular signal-regulated kinase (ERK1/2). We found that switching off v-Src led to a decrease in the activity of both PI3-K and ERK1/2, however, we found that adding a specific inhibitor of PI3-K (LY294002) to v-Src transformed Rat-1 cells grown in low serum induced apoptosis while a specific ERK kinase (MEK1) inhibitor (PD98059) had no effect. This suggests that v-Src protects from apoptosis under low serum conditions by activating PI3-K.

DNA topoisomerase IIalpha interacts with CAD nuclease and is involved in chromatin condensation during apoptotic execution

Apoptotic execution is characterized by dramatic changes in nuclear structure accompanied by cleavage of nuclear proteins by caspases (reviewed in [1]). Cell-free extracts have proved useful for the identification and functional characterization of activities involved in apoptotic execution [2-4] and for the identification of proteins cleaved by caspases [5]. More recent studies have suggested that nuclear disassembly is driven largely by factors activated downstream of caspases [6]. One such factor, the caspase-activated DNase, CAD/CPAN/DFF40 [4,7,8] (CAD) can induce apoptotic chromatin condensation in isolated HeLa cell nuclei in the absence of other cytosolic factors [6,8]. As chromatin condensation occurs even when CAD activity is inhibited, however, CAD cannot be the sole morphogenetic factor triggered by caspases [6]. Here we show that DNA topoisomerase IIalpha (Topo IIalpha), which is essential for both condensation and segregation of daughter chromosomes in mitosis [9], also functions during apoptotic execution. Simultaneous inhibition of Topo IIalpha and caspases completely abolishes apoptotic chromatin condensation. In addition, we show that CAD binds to Topo IIalpha, and that their association enhances the decatenation activity of Topo IIalpha in vitro.

Formation of spindle poles by dynein/dynactin-dependent transport of NuMA

NuMA is a large nuclear protein whose relocation to the spindle poles is required for bipolar mitotic spindle assembly. We show here that this process depends on directed NuMA transport toward microtubule minus ends powered by cytoplasmic dynein and its activator dynactin. Upon nuclear envelope breakdown, large cytoplasmic aggregates of green fluorescent protein (GFP)-tagged NuMA stream poleward along spindle fibers in association with the actin-related protein 1 (Arp1) protein of the dynactin complex and cytoplasmic dynein. Immunoprecipitations and gel filtration demonstrate the assembly of a reversible, mitosis-specific complex of NuMA with dynein and dynactin. NuMA transport is required for spindle pole assembly and maintenance, since disruption of the dynactin complex (by increasing the amount of the dynamitin subunit) or dynein function (with an antibody) strongly inhibits NuMA translocation and accumulation and disrupts spindle pole assembly.

Differential localization of ICAD-L and ICAD-S in cells due to removal of a C-terminal NLS from ICAD-L by alternative splicing

CAD/CPAN/DFF40 is an apoptotic nuclease that is associated with the regulatory subunit ICAD/DFF in healthy cells. ICAD has two forms, ICAD-L/DFF45 and ICAD-S/DFF35, which are transcribed from a single gene by alternative splicing. They differ at the C-terminus: 70 amino acids of ICAD-L are replaced by 4 different amino acids in ICAD-S. We previously showed that both transfected and endogenous ICAD-L are nuclear; however, the localization of ICAD and CAD remains controversial and an important issue to clarify. Here we present the evidence that ICAD-L is nuclear due to the presence of an autonomous nuclear localization signal located in the C-terminal 20 amino acids. This NLS is missing from ICAD-S, which is distributed throughout the cell. We also showed that a GFP:CAD fusion protein is located in the nucleus of transfected cells.

Probing the interaction between N(1),N(4)-dibenzylputrescine and tRNA through (15)N NMR: biological implications

NMR spectroscopy was used to characterize the binding properties of polyamines to Escherichia coli tRNA. The (15)N NMR spectra of three (15)N-enriched N-substituted putrescine derivatives (DMP, DEP and DBP) were recorded in the presence of tRNA, and the spin relaxation times of the nitrogen nuclei were measured. From these data, the activation parameters for the rotational correlation times of the (15)N nuclei were determined. The present data indicate that the nature of the amino substituents does play a relevant role in controlling the polyamine-tRNA interaction. This study also provides a rationale for the in vivo antiproliferative effect of DBP against tumoral cells.

Adaptive internal state space construction method for reinforcement learning of a real-world agent

One of the difficulties encountered in the application of the reinforcement learning to real-world problems is the construction of a discrete state space from a continuous sensory input signal. In the absence of a priori knowledge about the task, a straightforward approach to this problem is to discretize the input space into a grid, and to use a lookup table. However, this method suffers from the curse of dimensionality. Some studies use continuous function approximators such as neural networks instead of lookup tables. However, when global basis functions such as sigmoid functions are used, convergence cannot be guaranteed. To overcome this problem, we propose a method in which local basis functions are incrementally assigned depending on the task requirement. Initially, only one basis function is allocated over the entire space. The basis function is divided according to the statistical property of locally weighted temporal difference error (TD error) of the value function. We applied this method to an autonomous robot collision avoidance problem, and evaluated the validity of the algorithm in simulation. The proposed algorithm, which we call adaptive basis division (ABD) algorithm, achieved the task using a smaller number of basis functions than the conventional methods. Moreover, we applied the method to a goal-directed navigation problem of a real mobile robot. The action strategy was learned using a database of sensor data, and it was then used for navigation of a real machine. The robot reached the goal using a smaller number of internal states than with the conventional methods.

Role of factors downstream of caspases in nuclear disassembly during apoptotic execution

We used cytoplasmic extracts from chicken DU249 cells at various stages along the apoptotic pathway to analyse the events of apoptotic execution. So-called S/M extracts from morphologically normal 'committed-stage' cells induce apoptotic morphology and DNA cleavage in substrate nuclei. These apoptotic changes appear to require the function of multiple caspases (cysteine aspartases, a specialized class of proteases) acting in parallel. Extracts from 'execution-stage' apoptotic cells induce apoptotic events in added nuclei in a caspase-independent manner. Biochemical fractionation of these extracts reveals that a column fraction enriched in endogenous active caspases is unable to induce DNA fragmentation or chromatin condensation in substrate nuclei, whereas a caspase-depleted fraction induces both changes. 'Execution-stage' extracts contain an ICAD/DFF45-inhibitable nuclease resembling CAD, plus another activity that is required for the apoptotic chromatin condensation. 'Committed-stage' S/M extracts lack these downstream activities. These observations reveal that caspases act in an executive fashion, serving to activate downstream factors that disassemble the nucleus rather than disassembling it themselves. They also suggest that activation of the downstream factors (rather than the caspases) is the critical event that occurs at the transition from the latent to the execution phase of apoptosis.

Primary structure of rat spermidine synthase: an example of refining the cDNA-derived amino acid sequence

The primary structure of rat spermidine synthase having the N-terminal acetylated methionine and 98.7% homology with that of the mouse enzyme is presented using a limited amount of the homogeneous enzyme. The study strategy was principally to compare the molecular masses of liberated peptides determined by three specific cleavage methods with those expected from known cDNA-derived amino acid sequences of mouse and human enzymes using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF-MS). The cleavage methods involved two enzymatic methods using lysylendopeptidase and arginylendopeptidase, and a chemical method for cleaving at the cysteine residue using 2-nitro-5-thiocyanobenzoic acid. Their usefulness was clearly demonstrated. Column-switching semimicro reversed-phase HPLC, which permits application of the entire reaction mixture, was useful for collecting a small amount of peptides containing the N-terminal amino acid, to confirm acetylation of the N-terminal methionine by MALDI TOF-MS. It was necessary in this approach to examine the amino acid sequence of certain peptides. The Edman method was used for the sequence analysis, and this will be replaced by an improved MALDI TOF-MS now available in a few laboratories.

Arginyl-tRNA-protein transferase activities in crude supernatants of rat tissues

A fluorescent HPLC method for the assay of arginyl-tRNA-protein transferase (R-Transferase) activity was applied to obtain quantitative data of the enzyme activity in rat tissues for the first time. In this assay, the major problem was a significant hydrolysis of the substrate, N-aspartyl-N'-dansylamido-1,4-butanediamine, and the product, N-arginylaspartyl-N'-dansylamido-1,4-butanediamine (ArgAsp(4)DNS) by aminopeptidases in crude samples such as 105000g supernatants (105S) of tissue homogenates. As bestatin inhibited the hydrolysis of ArgAsp(4)DNS, a standard-addition method in the presence of bestatin, using a partially purified R-Transferase preparation from hog kidney as a standard, made it possible to measure directly R-Transferase activities in 105S with a short incubation time and sufficient reliability. It was found by the established method that of 14 tissues examined, stomach was rich in the R-Transferase activity with the highest specific activity, suggesting a target tissue for the future studies on R-Transferase to elucidate its physiological significance.

Preparation and usefulness of some fluorogenic substrates for assay of arginyl-tRNA-protein transferase by HPLC

A series of fluorescent substrates and products was prepared and evaluated for the assay of arginyl-tRNA-protein transferase (arginyltransferase) activity by HPLC. Since N-aspartyl-N'-dansylamido-1,4-butanediamine (Asp(4)DNS) was the most suitable substrate of the compounds tested, which had a three-, four-, or five-methylene-chain interval between Asp or Glu and DNS, the following enzymatic studies were focussed on Asp(4)DNS and its product, N-arginylaspartyl-N'-dansylamido-1,4-butanediamine (ArgAsp(4)DNS). The apparent Km value for Asp(4)DNS was calculated to be 30 microM using a hydroxyapatite-treated arginyltransferase preparation from hog kidney, which was free from any enzyme that might decompose the two compounds. The present HPLC method was shown to be advantageous in reliability and sensitivity compared to the available isotope paper disk method using the hydroxyapatite-treated enzyme preparation and in applicability to crude samples examined using a DEAE-treated arginyltransferase preparation and 105,000g supernatant (105S) from hog kidney. Stepwise elimination of Arg and Asp from ArgAsp(4)DNS was observed with the two crude enzyme solutions, and the elimination of Arg was suppressed by the addition of bestatin, suggesting the participation of certain aminopeptidases. Although Asp(4)DNS was decomposed significantly with 105S, an incubation-time-dependent linear elevation of ArgAsp(4)DNS was maintained for 5 min in the presence of bestatin. Furthermore, an addition-recovery test of the DEAE-treated enzyme preparation for the 105S assured accurate determination of arginyltransferase activity in the 105S under the tentatively established conditions. The present HPLC method, which permits the simultaneous determination of 4-dansylamidobutylamine, Asp(4)DNS, and ArgAsp(4)DNS, was advantageous in measuring arginyltransferase activity and detecting the presence of unfavorable enzyme(s) in samples to ensure accurate determination.

Caspase-mediated cleavage of DNA topoisomerase I at unconventional sites during apoptosis

Previous studies have demonstrated that topoisomerase I is cleaved late during apoptosis, but have not identified the proteases responsible or examined the functional consequences of this cleavage. Here, we have shown that treatment of purified topoisomerase I with caspase-3 resulted in cleavage at DDVD146 downward arrowY and EEED170 downward arrowG, whereas treatment with caspase-6 resulted in cleavage at PEDD123 downward arrowG and EEED170 downward arrowG. After treatment of Jurkat T lymphocytic leukemia cells with anti-Fas antibody or A549 lung cancer cells with topotecan, etoposide, or paclitaxel, the topoisomerase I fragment comigrated with the product that resulted from caspase-3 cleavage at DDVD146 downward arrowY. In contrast, two discrete topoisomerase I fragments that appeared to result from cleavage at DDVD146 downward arrowY and EEED170 downward arrowG were observed after treatment of MDA-MB-468 breast cancer cells with paclitaxel. Topoisomerase I cleavage did not occur in apoptotic MCF-7 cells, which lack caspase-3. Cell fractionation and band depletion studies with the topoisomerase I poison topotecan revealed that the topoisomerase I fragment remains in proximity to the chromatin and retains the ability to bind to and cleave DNA. These observations indicate that topoisomerase I is a substrate of caspase-3 and possibly caspase-6, but is cleaved at sequences that differ from those ordinarily preferred by these enzymes, thereby providing a potential explanation why topoisomerase I cleavage lags behind that of classical caspase substrates such as poly(ADP-ribose) polymerase and lamin B1.

Ionspray ionization-mass spectrometric separation and determination of heptafluorobutyryl derivatives of polyamines

We describe here an application of ionspray ionization-mass spectrometry (IS-MS) for simultaneous determination of putrescine, spermidine, and spermine without the need for coupling with other separation techniques such as high-performance liquid chromatography or capillary electrophoresis. Because it was essential to increase the mass of these compounds to eliminate contaminated low-mass ions, heptafluorobutyryl (HFB) derivatives were chosen. It was found that each HFB-polyamine appeared as a single major cation carrying an ammonium ion in a solution of 50% acetonitrile-water containing 0.5% ammonium acetate at an orifice potential of 20 V. Under these conditions, the three polyamines after addition of 15N-labeled polyamines as internal standards, followed by heptafluorobutylation, were determined simultaneously. It was shown, using a sample injection bulb set between the syringe drive and ionspray probe, that the analysis time for data acquisition was about 3 min and the sensitivity was about 10 fmol. In addition, polyamines in rat liver were determined by this method after simple fractionation with a small column of CM-cellulose with reasonable accuracy and precision. Behaviors of acetylated polyamines were also described, and the results showed that the acetylated polyamines would become additional target compounds in the present method.

Transition from caspase-dependent to caspase-independent mechanisms at the onset of apoptotic execution

We have compared cytoplasmic extracts from chicken DU249 cells at various stages along the apoptotic pathway. Extracts from morphologically normal "committed stage" cells induce apoptotic morphology and DNA cleavage in substrate nuclei but require ongoing caspase activity to do so. In contrast, extracts from frankly apoptotic cells induce apoptotic events in added nuclei in a caspase-independent manner. Biochemical fractionation of these extracts reveals that a column fraction enriched in endogenous active caspases is unable to induce DNA fragmentation or chromatin condensation in substrate nuclei, whereas a caspase-depleted fraction induces both changes. Further characterization of the "execution phase" extracts revealed the presence of an ICAD/DFF45 (inhibitor of caspase-activated DNase/DNA fragmentation factor)- inhibitable nuclease resembling CAD, plus another activity that was required for the apoptotic chromatin condensation. Despite the presence of active caspases, committed stage extracts lacked these downstream activities, suggesting that the caspases and downstream factors are segregated from one another in vivo during the latent phase. These observations not only indicate that caspases act in an executive fashion, serving to activate downstream factors that disassemble the nucleus rather than disassembling it themselves, but they also suggest that activation of the downstream factors (rather than the caspases) is the critical event that occurs at the transition from the latent to active phase of apoptosis.

ICAD/DFF regulator of apoptotic nuclease is nuclear

In nonapoptotic cells, the caspase-activated DNase CAD/CPAN is associated with a regulatory subunit, ICAD/DFF, that binds to it and blocks its enzymatic activity. It has been proposed that a major function of ICAD is to restrain CAD in the cytoplasm in healthy cells. The experiments presented here demonstrate that rather than being cytoplasmic, a GFP-ICAD fusion protein is nuclear in healthy human, pig, and chicken cells. Furthermore, immunoblots using antibodies to murine ICAD confirm the presence of endogenous ICAD and the marker protein DNA topoisomerase I in human nuclei, while tubulin was found solely in the cytosolic fraction. Since ICAD is located in cell nuclei, it is unlikely that the protein functions primarily in the cytoplasm either as an anchor for CAD/CPAN or as a factor that enters the nucleus following caspase cleavage in order to activate resident endonucleases.

[Methodological approach to regulation of polyamine]

This brief article is dedicated to the late Professor Morizo Ishidate, and concerned in a methodology developed by the author and collaborators, aiming at the regulation of polyamine, especially, the regulation of spermidine synthase. The content is separated in 3 sections. The first section on the development of analytical methods, contains seven items, e.g. fluorometric determination of polyamines by fluorescamine, analysis of naturally occurring polyamines by GC and GC-MS, etc. The second section on the syntheses of needed compounds, contains three items, e.g. syntheses of decarboxylated S-adenosylmethionine which is a substrate for spermidine synthase and its related compounds, syntheses of 15N-enriched polyamines applicable to the preparation of various polyamines, etc. The last section on the studies of aminopropyl transferases, contains three items, e.g. purification of spermidine synthase from mammalian tissues using ATPA-Sepharose, a novel affinity carrier, newly developed inhibitors for the enzymes, etc.

Structural requirement for axonal regeneration-promoting effect of polyamines in cultured rat hippocampal neurons

We have previously found that spermine, spermidine and putrescine promote axonal regeneration following axotomy in cultured rat hippocampal neurons. In the present study, we investigated which part of the polyamine molecule is responsible for the regeneration-promoting effect. Testing the effects of several synthetic analogues revealed that the butanediamine moiety is essential for the activity and the terminal primary amines are necessary for full agonist activity. The structure-activity relationship indicates that the regeneration-promoting effects of polyamines are not associated with NMDA receptors.

Determination of covalently bound hypusine and deoxyhypusine to protein using submilligram of protein samples by HPLC

A sensitive and reliable method for the determination of hypusine and deoxyhypusine in eIF-5A protein, an initiation factor of protein synthesis, was developed. An advantage of this method is the use of N epsilon-(5-aminopentyl)lysine, an analogue of deoxyhypusine, as an internal standard. The application made it possible to determine hypusine in less than a mg of protein samples from cultured HTC cells and rat organs. After acid hydrolysis of protein samples to which had been added the internal standard, the hydrolysates were fractionated by carboxymethyl cellulose column chromatography. Also, diamine fractions containing a few pmol of hypusine and deoxyhypusine were successfully analyzed by a reversed phase HPLC with a fluorescence detection of o-phthalaldehyde. The method was applied for the determination of hypusine and deoxyhypusine in drug-treated HTC cells and normal rat organs. The results from HTC cells were discussed based on the known effects of each drug on hypusine biosynthesis.

Antagonistic effect of N-(3-Aminopropyl)cyclohexylamine on neurotrophic action of spermine in primary cultured rat hippocampal and cerebellar neurons

We previously found that spermine potently promotes the neuronal survival and regeneration of primary cultured brain neurons. N-(3-Aminopropyl)cyclohexylamine (APCHA) was originally developed as a spermine synthase inhibitor. To test if endogenous spermine biosynthesis contributes to neuronal survival and morphogenesis, we examined the effects of APCHA in primary cultured rat hippocampal and cerebellar neurons. APCHA at concentrations up to 10(-6) M did not affect the neuronal survival, but significantly blocked the survival-promoting effect of spermine (10(-8) M). APCHA also blocked the spermine-induced promotion of neurite regeneration following axotomy. Unlike APCHA, another cyclohexylamine derivative trans-4-methylcyclohexylamine did not affect the neurotrophic effect of spermine. These results suggest that in primary cultured brain neurons, APCHA works as a spermine antagonist rather than as a spermine synthesis inhibitor.

Identification of N4-(2-propenal)spermidine as a major reaction product of malondialdehyde and spermidine

The reactivity of malondialdehyde(MDA) with spermidine at the physiological pH was considerably higher than that with putrescine, glycine, lysine, methylamine or dimethylamine, and the major reaction product of MDA-spermidine adduct was identified as N4-(2-propenal)spermidine.

Search for novel ligands selective at a polyamine recognition domain on the N-methyl-D-aspartate receptor complex using membrane binding techniques

Among over 60 polyamine derivatives tested, only N-(3-aminopropyl)octanediamine and bis-(3-aminopropyl)nonanediamine (TE393) markedly inhibited [3H](+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imi ne (MK-801) binding at equilibrium in the presence of added spermidine (SPD) in "non-washed" rat brain synaptic membranes, without affecting that in the absence of added SPD. Although TE393 significantly potentiated [3H]MK-801 binding before equilibrium in the presence of L-glutamic acid (Glu) alone or both Glu and glycine (Gly) added in "Triton-treated" membranes, the putative polyamine antagonists 1,10-decanediamine (DA10) and arcaine invariably inhibited binding irrespective of the addition of agonists. In the absence of added SPD, in addition, TE393 markedly enhanced abilities of both Glu and Gly to potentiate [3H]MK-801 binding before equilibrium. However, TE393 induced a rightward shift of the concentration-response curve of SPD for [3H]MK-801 binding before equilibrium. Moreover, TE393 was effective in potentiating binding of an antagonist but not an agonist radioligand to the NMDA domain and in inhibiting binding of an antagonist but not an agonist radioligand to the Gly domain. The potentiation of NMDA antagonist binding by TE393 occurred in a manner sensitive to prevention by arcaine but not by DA10. These results suggest that TE393 may be a novel ligand at the polyamine domain with an ability to interact with both the NMDA and Gly recognition domains in antagonist-preferring forms.

Enzymatic aminopropylation of certain secondary amines

Two unusual aminopropyl acceptors found in a survey of putrescine binding sites of mammalian spermidine synthase, N-methylputrescine (I) and 4-aminomethylpiperidine (II), were examined for their aminopropyl derivatives. Studies under in vitro incubation conditions suggested that the aminopropyl derivatives of the secondary amine of I and II, N4-methylspermidine (Is) and 1-N-(3-aminopropyl)-4-aminomethylpiperidine (IIs), and of the primary amine of I and II, N8-methylspermidine (Ip) and 4-[N-(3-aminopropyl)aminomethyl]piperidine (IIp), respectively, were biosynthesized by rat spermidine synthase. Studies on the cell culture system of cultured rat hepatoma (HTC) cells treated with alpha-difluoromethylornithine, an ornithine decarboxylase inhibitor, clearly showed the presence of Is and Ip when I was administered, and IIs and IIp when II was administered, with no detection of putrescine or spermidine. These results suggested that mammalian spermidine synthase can transfer the aminopropyl moiety of decarboxylated S-adenosylmethionine to certain secondary amines in living cells.

Structural requirement for neurotrophic activity of spermine in cultured rat hippocampal neurons

We investigated the structure-activity relationship for the neurotrophic activity of spermine by comparing the effects of several synthetic spermine analogues on the survival of cultured rat hippocampal neurons. N,N'-bis(3-aminopropyl)-1,6-hexanediamine and N,N'-bis(3-aminopropyl)-1,3-propanediamine did not promote the neuronal survival, suggesting that the central butanediamine structure is essential for the neurotrophic activity. Furthermore, N1,N12-bis(ethyl)spermine significantly promoted the neuron survival, but its maximum effect was smaller than that of spermine, indicating that two terminal primary amines are required for full agonist activity. The structural requirement for the neurotrophic activity of spermine was different from those for any other reported activities of polyamines.