Kidney enlargement and multiple liver cyst formation implicate mutations in PKD1/2 in adult sporadic polycystic kidney disease.

Distinguishing autosomal-dominant polycystic kidney disease (ADPKD) from other inherited renal cystic diseases in patients with adult polycystic kidney disease and no family history is critical for correct treatment and appropriate genetic counseling. However, for patients with no family history, there are no definitive imaging findings that provide an unequivocal ADPKD diagnosis. We analyzed 53 adult polycystic kidney disease patients with no family history. Comprehensive genetic testing was performed using capture-based next-generation sequencing for 69 genes currently known to cause hereditary renal cystic diseases including ADPKD. Through our analysis, 32 patients had PKD1 or PKD2 mutations. Additionally, 3 patients with disease-causing mutations in NPHP4, PKHD1, and OFD1 were diagnosed with an inherited renal cystic disease other than ADPKD. In patients with PKD1 or PKD2 mutations, the prevalence of polycystic liver disease, defined as more than 20 liver cysts, was significantly higher (71.9% vs 33.3%, P = .006), total kidney volume was significantly increased (median, 1580.7 mL vs 791.0 mL, P = .027) and mean arterial pressure was significantly higher (median, 98 mm Hg vs 91 mm Hg, P = .012). The genetic screening approach and clinical features described here are potentially beneficial for optimal management of adult sporadic polycystic kidney disease patients.

Once-weekly teriparatide in hemodialysis patients with hypoparathyroidism and low bone mass: a prospective study.

UNLABELLED: Once-weekly 56.5-µg teriparatide treatment was significantly associated with the increase in lumbar spine bone mineral density at 48 weeks among hemodialysis patients with hypoparathyroidism and low bone mass; however, discontinuation of treatment because of adverse events was frequently observed. Careful monitoring for adverse events should be required. INTRODUCTION: Once-weekly 56.5-µg teriparatide is reportedly effective for treating osteoporotic patients without renal insufficiency. However, little is known about the efficacy and safety of once-weekly teriparatide in hemodialysis patients. METHODS: We conducted a 48-week prospective, observational cohort study including 22 hemodialysis patients aged 20 years or older with hypoparathyroidism and low bone mass who received once-weekly teriparatide at 56.5 µg at a tertiary care hospital between January 2013 and January 2015. Primary outcomes were within-subject percent changes of bone mineral density (BMD) at the lumbar spine, femoral neck, and distal one-third radius at 24 and 48 weeks. Secondary outcomes included percent changes of serum bone turnover markers (osteocalcin, bone-specific alkaline phosphatase (BAP), N-terminal propeptide of procollagen type 1 (P1NP), and tartrate-resistant acid phosphatase 5b (TRAP-5b)). Adverse events were evaluated. RESULTS: The BMD increased at the lumbar spine by 3.3 ± 1.9 % (mean ± SEM) and 3.0 ± 1.8 % at 24 and 48 weeks but not in the femoral neck and distal one-third radius. Serum osteocalcin, BAP, and P1NP increased significantly at 4 weeks, maintaining higher concentrations up to 48 weeks, although TRAP-5b decreased gradually during treatment. The baseline BAP was significantly associated with the 48-week percent change in lumbar spine BMD. Transient hypotension was the most common adverse event. Ten patients discontinued treatment because of adverse events. CONCLUSIONS: Once-weekly teriparatide was associated with increased lumbar spine BMD in hemodialysis patients with hypoparathyroidism and low bone mass. Careful monitoring should be required for treatment of such patients.

Bone histomorphometry in a long-term hemodialysis patient with hypoparathyroidism and sarcoidosis.

A bone biopsy specimen in a long-term hemodialysis patient with sarcoidosis coexisting with severe hypoparathyroidism has demonstrated that a persistent near physiological level of 1,25-dihydroxyvitamin D3 contributes to the preservation of bone remodeling and has the potential to retard the development of vascular calcification and atherosclerosis. Sarcoidosis-related hypercalcemia and hypoparathyroidism, which is characterized by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) overproduction, is rarely seen in hemodialysis patients. Herein, we describe a 60-year-old Japanese woman on hemodialysis for 35 years who presented with malaise and hypercalcemia. Severe hypoparathyroidism without parathyroidectomy and a preserved 1,25(OH)2D3 level were detected. Computed tomography showed bilateral axillary lymphadenopathy and minimal aortic and soft tissue calcification. The axillary node biopsy led to a definite diagnosis of sarcoidosis. A bone biopsy specimen obtained from the right iliac crest showed remodeling of normal lamellar bone with scalloped cement lines and clear double labeling by tetracycline on fluorescence microscopy. Histomorphometric analysis revealed that the bone formation rate was preserved (30.0 %/year), together with a decrease of osteoid volume (5.75 %) and fibrous volume (0 %), indicating that the patient did not have adynamic bone disease and only showed mild disease. This is the first documented case of sarcoidosis-related hypercalcemia associated with severe hypoparathyroidism in a long-term hemodialysis patient who underwent bone histomorphometry. Our findings suggest that, in hemodialysis patients with sarcoidosis coexisting with severe hypoparathyroidism, a persistent near physiological level of 1,25(OH)2D3 contributes to the preservation of bone remodeling and has the potential to retard the development of vascular calcification and atherosclerosis.

Impact of tubulointerstitial lesions on anaemia in patients with biopsy-proven diabetic nephropathy.

AIMS: To investigate the relationship between the progression of anaemia and renal pathological findings in patients with diabetic nephropathy. METHODS: A total of 223 patients with diabetes underwent renal biopsy from 1985 to 2010 and were confirmed to have pure diabetic nephropathy according to the recent classification, of whom 113 (baseline haemoglobin ≥ 11 g/dl) were enrolled in the study. Linear regression analysis was used to estimate the changes in haemoglobin levels during the follow-up period. RESULTS: In a multivariate model adjusted for clinical and histopathological variables, higher interstitial fibrosis and tubular atrophy scores were more strongly associated with a decrease in haemoglobin levels than were lower scores. Compared with an interstitial fibrosis and tubular atrophy score of 0, the standardized coefficients for interstitial fibrosis and tubular atrophy scores of 1, 2 and 3 were 0.20 (95% CI -0.31 to 0.93), 0.34 (95% CI -0.22 to 1.34) and 0.47 (95% CI 0.07 to 1.96), respectively, whereas a higher glomerular class, a higher vascular lesion score and the presence of exudative lesions were not strongly correlated with the decrease in haemoglobin. CONCLUSIONS: Tubulointerstitial lesions that are more advanced are significantly associated with the progression of anaemia in patients with diabetic nephropathy after adjustment for numerous covariates. This finding suggests that tubulointerstitial lesions may be a useful prognostic indicator for anaemia in patients with diabetic nephropathy, and that decreased erythropoietin production attributable to the progression of tubulointerstitial lesions is a major cause of anaemia in these patients.

Cyst infection in autosomal dominant polycystic kidney disease: causative microorganisms and susceptibility to lipid-soluble antibiotics.

Cyst infection is a frequent and serious complication of autosomal dominant polycystic kidney disease (ADPKD). Lipid-soluble antibiotics like fluoroquinolones show good penetration into cysts and are recommended for cyst infection, but causative microorganisms are often resistant to these agents. This study investigated the profile of the microorganisms causing cyst infection in ADPKD, their susceptibility to lipid-soluble antibiotics, and clinical outcomes. This retrospective study reviewed all ADPKD patients admitted to Toranomon Hospital with a diagnosis of cyst infection from January 2004 to March 2014. All patients who underwent cyst drainage and had positive cyst fluid cultures were enrolled. Patients with positive blood cultures who satisfied our criteria for cyst infection or probable infection were also enrolled. There were 99 episodes with positive cyst fluid cultures and 93 episodes with positive blood cultures. The majority of patients were on dialysis. The death rate was high when infection was caused by multiple microorganisms or when there were multiple infected cysts. Gram-negative bacteria accounted for 74-79 % of the isolates in all groups, except for patients with positive hepatic cyst fluid cultures. The susceptibility of Escherichia coli to fluoroquinolones was very low in patients with hepatic cyst infection, especially those with frequent episodes and those with hepatomegaly. Fungi were detected in two episodes. Fluoroquinolone-resistant microorganisms showed a high prevalence in cyst infection. It is important to identify causative microorganisms to avoid the overuse of fluoroquinolones and to improve the outcome of cyst infection in ADPKD.

A case of familial lecithin-cholesterol acyltransferase deficiency on hemodialysis for over 20 years.

We trace the 34-year history of a member of the first Japanese family in which lecithin-cholesterol acyltransferase (LCAT) deficiency was diagnosed. Marriage between cousins with low LCAT activity was responsible for familial LCAT deficiency (FLD). In 1976, a 27-year-old Japanese man was noted to have FLD based on proteinuria, hematuria, grayish corneal opacity and low LCAT activity (9.83%). Genetic analysis showed insertion of G-G-C coding glycine at codon 141. Total cholesterol (C) was low at 108 mg/dl and the ratio of C-ester to total C was very low (12%), while the lecithin (phosphatidylcholine) level was very high (97.3%). When his serum creatinine reached 2.6 mg/dl at the age of 41 years (in 1991), renal biopsy was performed. This showed expansion of the mesangial matrix and irregularly thickened capillary walls with a bubble-like appearance because of lipid deposits consisting of two components (partly lucent vacuolated areas and partly deeply osmiophilic areas). Magnification of the latter deposits showed curvilinear and serpiginous striated membranous structure. Hemodialysis was started in 1990 and has been continued for over 20 years until August 2010. Clinical problems have included AV shunt failure requiring 4 operations and 13 percutaneous transcatheter angioplasty procedures, as well as episodes of hemolytic anemia that subsided after infusion of fresh frozen plasma. Cardiovascular events have not yet occurred, although severe calcification of abdominal aorta has been detected by computed tomography.

Hepatitis C virus-related kidney disease: various histological patterns.

BACKGROUND: Although hepatitis C virus (HCV) infection is known to be associated with Type 2 cryoglobulinemic glomerulopathy (CG), only a few reports about other types of nephropathy have been published. METHODS: 68 HCV antibody positive patients in whom renal biopsy had been performed for persistent proteinuria, hematuria, and/or renal dysfunction between 1992 and 2008 at our institute were included. The histological, clinical and laboratory characteristics including the age, gender, hypertension, diabetes mellitus, liver histology (chronic hepatitis or liver cirrhosis), HCV-RNA, HCV genotype, splenomegaly, gastroesophageal varices, serum creatinine, hemoglobin, platelet count, rheumatoid factor, cryoglobulin, IgG, IgA, IgM, CH50, C3, C4, creatinine clearance, 24-h protein excretion, and hematuria, between their nephropathy with and without immune deposition were compared. RESULTS: Nephropathy was classified into two groups based on the detection of immune deposits by immunofluorescence microscopy: i.e., a positive group (n = 39) and a negative group (n = 29). The former group was further classified into three types of nephropathy: IgG dominant group (n = 10) (including membranous nephropathy (MN)), IgA dominant group (n = 20) (including IgA nephropathy (IgAN)), membranoproliferative glomerulonephritis (MPGN) (IgA type)), and IgM dominant group (n = 9) (MPGN apart from the IgA type). The latter group included diabetic nephropathy (n = 13), focal glomerular sclerosis (n = 4), and benign nephrosclerosis (n = 3), malignant nephrosclerosis (n = 1), tubulointerstitial nephritis (TIN) (n = 2), minimal change nephrotic syndrome (n = 1), cast nephropathy (n = 1), granulomatous TIN (n = 1), and others (n = 3). An increased serum IgM level, hypocomplementemia, splenomegaly, thrombocytopenia, liver cirrhosis, hematuria, and a high HCV RNA level were features of patients with MPGN of IgM dominant group (consistent with "CG"). CONCLUSIONS: Our results showed various histological patterns of HCV-related kidney disease and the specificity of CG, and revealed that a minority of HCV patients (n = 7) presented typical CG, while IgAN, MN, and diabetic nephropathy were more frequent.

[Redo-operation for the cusp perforation 5 years after aortic valve replacement with stentless bioprosthesis; report of a case].

A 31-year-old male presented with increase of aortic valve regurgitation 5 years after implantation of Prima Plus Stentless bioprosthesis in a bicuspid aortic valve. He underwent redo aortic valve replacement with a mechanical valve concomitant with replacement of the ascending aorta. Pathological examination of the explanted stentless valve presented no inflammatory cell infiltration. The prosthetic valve regurgitation was considered to be due to small injury at the 1st operation.

The long-term survival rate of catecholamine-resistant septic shock in Japanese patients who received vasopressin therapy.

BACKGROUND: Septic shock is associated with vasopressin deficiency and hypersensitivity to its exogenous administration. The aim of this study is to review the 28-day survival rate, hemodynamic and renal effects of vasopressin therapy in refractory septic shock Japanese patients. METHODS: 55 Japanese patients experiencing catecholamine-resistant septic shock were treated with vasopressin. Hemodynamic alterations and the serum concentrations of aspartate aminotransferase, total bilirubin and creatinine clearance were evaluated following vasopressin treatment. RESULTS: In both, survivors and non-surviving patients, treatment with vasopressin resulted in a significantly increase in mean arterial pressure, hourly urine output, and a significant decrease in heart rate and total pressor dosage requirements. Creatinine clearance was significantly increased only in survivors. There were no significant changes in the serum concentrations of aspartate aminotransferase and total bilirubin. The 28-day survival rate was 45% (25 patients). CONCLUSIONS: In Japanese septic shock patients, vasopressin infusion improved hemodynamic status and reduced catecholamine requirement, and 28-day survival rate was 45%.

A patient with pregnancy-related acute abdomen after hemodialysis for over 18 years.

Because pregnancy is rare in women with end-stage renal disease, dialysis patients have not been reported to present with acute abdominal symptoms related to pregnancy including ectopic pregnancy. A 41-year-old woman treated with hemodialysis for over 18 years was brought to the emergency room at our institution because of acute abdominal pain. Ultrasonography detected an abdominal fluid collection, and her anemia had worsened (hematocrit 18%). Emergency laparoscopic exploration disclosed a hemorrhagic corpus luteum of pregnancy, causing ovarian bleeding on the left. Coagulation of bleeding points was carried out. At this time, pregnancy at 7 weeks of gestation was discovered. After the procedures, hemodialysis frequency was increased to 5 times weekly, and an erythropoietin derivative was administered to maintain a hematocrit above 30%. The patient developed no hypertension. At 33 weeks of gestation, cesarean section was performed because of a decrease in amniotic fluid and frequent late deceleration of the fetal heart rate. A live baby girl weighing 1,422 g was born. The successful pregnancy reflects remarkable progress in dialysis technology. Pregnancy, then, can underlie an acute abdomen in childbearing-age women (14 - 44 years old) undergoing long-term dialysis.

[Surgical treatment for ischemic heart disease].

BACKGROUND: Surgical treatment for ischemic heart disease (IHD) has changed after the administration of off-pump coronary artery bypass grafting (CABG) [OPCAB] and left ventricular restoration (LVR). We studied the development of the treatment and the surgical results. PATIENTS AND METHODS: Since May 2000 when the indication for OPCAB and LVR was defined, surgical treatment for IHD has been performed in 1,251 patients. The age ranged from 32 to 91 (mean 66 +/- 10) years and there were 977 men and 274 women. The elective operation was 1,130 and emergency 121. Definite indication for OPCAB was calcified ascending aorta, significant cerebrovascular disease, hemorrhagic tendency, and single vessel lesion. Conventional CABG (C-CAB) was the first choice and morbidity and surgical results were examined. RESULTS: OPCAB was performed in 297 (29.9%) and combined operation with CABG was required in 258 patients (20.6%). In elective operation, hospital mortality was one in OPCAB and one in C-CAB. In OPCAB and C-CAB, stroke was none and one, and mediastinitis was 0 and 0, respectively. CONCLUSION: The technique for OPCAB is necessary for CABG; however, it is not appropriate to persist with only OPCAB for CABG. Combined operation is often required with CABG and it is essential to perform precise C-CAB.

Multicentric Castleman disease with secondary AA renal amyloidosis, nephrotic syndrome and chronic renal failure, remission after high-dose melphalan and autologous stem cell transplantation.

Multicentric Castleman disease is a systemic lymphoproliferative disease with incomplete understood etiology. The various renal complications of this disease may include minimal change disease, mesangial proliferative glomerulonephritis, membranous glomerulonephritis and nephrotic syndrome, caused by secondary amyloidosis. In several reported cases of localized Castleman disease associated with renal amyloidosis and nephrotic syndrome, resection of organs involved by lymphoid proliferation resulted in complete remission. However, therapy of multicentric Castleman disease with renal amyloidosis is not well-established. We treated a case of a 39-year-old woman with multicentric Castleman disease complicated by nephrotic syndrome caused by secondary AA amyloidosis. The patient underwent autologous peripheral blood stem cell transplantation (auto-PBSCT), achieving complete remission. Autologous stem cell transplantation may be an attractive choice in therapy for refractory multicentric Castleman disease.

A pediatric occurrence of crescentic glomerulonephritis associated with antineutrophil cytoplasmic antibodies and mesangial IgA deposits.

Antineutrophil cytoplasmic antibody-(ANCA) associated glomerulonephritis usually shows histopathologic features of pauciimmune crescentic glomerulonephritis and occurs late in life. We report a 14-year-old Japanese girl presenting with proteinuria, hematuria and mildly elevated serum creatinine. A renal biopsy specimen demonstrated crescentic glomerulonephritis, immunofluorescence showed mesangial IgA staining. Electron microscopic examination disclosed paramesangial deposits. Serum ANCA against myeloperoxidase (MPO) were detected at high titers. Myeloperoxidase-ANCA-related nephritis accompanied by IgA nephropathy is considered rare in childhood and teen years. Yet, if ANCA assays and detailed electron microscopic examination of renal specimens were performed routinely in patients with rapidly progressive glomerulonephritis, the diagnosis might be more frequent in young patients.

Nicotinamide methylation and its relation to NAD synthesis in rat liver tissue culture. Biochemical basis for the physiological activities of 1-methylnicotinamide.

The mode of [14C]nicotinamide conversion to NAD and 1-methylnicotinamide and the effects of exogenous 1-methylnicotinamide on this metabolic conversion were studied using rat liver slices incubated in a chemically defined culture medium. It was shown that at the physiological nicotinamide concentrations tested (11-500 microM), 1-methylnicotinamide is preferentially produced, rather than NAD. Upon increasing nicotinamide concentration to the levels that cause cytotoxicity (1-10 mM and higher), the rate of NAD synthesis dramatically increased and reached a level 6-fold higher than that of 1-methylnicotinamide. A dose-dependent inhibition (up to 60%) of NAD synthesis was seen by the exogenous addition of 1-methylnicotinamide; the degree of inhibition is affected also by the concentration of nicotinamide present as a precursor. A large depletion of intracellular ATP, associated with a marked accumulation of NAD, occurred in slices in response to the addition of high amounts of nicotinamide. However, the loss of ATP was overcome, when nicotinamide was given together with 1-methylnicotinamide. Finally, 1-methylnicotinamide per se was proven active in regulating cell growth by comparing the cytosolic activity of 1-methylnicotinamide oxidation of cultured RLC cells with that of rat liver. Thus, the previously observed growth stimulation of hepatic cells by 1-methylnicotinamide can reasonably been explained by its ATP-sparing effect due to the inhibition of NAD synthesis, a reaction which requires ATP.

Nicotinamide methylation. Tissue distribution, developmental and neoplastic changes.

The distribution of cytosolic activity of nicotinamide:S-adenosylmethionine methyltransferase (nicotinamide methylase, EC 2.1.1.1) in normal tissues from adult rat and mouse and in tumors and the change in the enzyme activity during the development of rat tissues were studied. (1) Rat liver exhibited the highest nicotinamide methylase activity among all adult tissues tested; other rat tissues, like adrenal, pancreas, kidney, brain and mouse tissues, had only less than 15% of the adult rat liver activity. (2) 3 days before birth, fetal liver showed a very low nicotinamide methylase activity (2% of adult rat liver), which, however, increased already 1 day before birth and reached the adult level on the day 28 after birth. (3) In a variety of hepatomas and ascites tumors, an inverse correlation, with some exceptions, between tumor growth rate and nicotinamide methylase activity could be seen. In all hepatomas, with the exception of Morris hepatoma 5123tc, nicotinamide methylase activity was significantly decreased in comparison to normal adult rat liver. The highly malignant Zajdela hepatoma, Yoshida sarcoma, sarcoma 180 and Ehrlich ascites tumor methylated nicotinamide only at a negligibly low rate. (4) Cultured RLC cells (an established rat liver cell line) from the stationary growth phase or G1-arrested RLC cells had about half of the adult rat liver activity, yet the activity was 70% higher than that of the logarithmically growing RLC cells.

3-Aminobenzamide enhances dexamethasone-mediated mouse thymocyte depletion in vivo: implication for a role of poly ADP-ribosylation in the negative selection of immature thymocytes.

3-Aminobenzamide (3-ABAm), an inhibitor of poly ADP-ribosylation, was here found to remarkably enhance the dexamethasone (Dex)-mediated depletion of total mouse thymocytes within 24 h post-injection, when given i.p. in combination with Dex. After treatment the total thymocytes were fractionated by Percoll gradient centrifugation into two mitogen-unresponsive (high- and medium-density) and one mitogen-reactive (low-density) subpopulations and these were analyzed for the phenotypic expression of CD4 and CD8 antigens. Treatment with Dex alone most extensively depleted the high- and medium-density thymocytes and also those expressing both CD4 and CD8 double positive (DP) phenotypes in all three subpopulations. The CD4+ and CD8+ single positive (SP) and CD4-CD8- double negative (DN) subsets, in the low-density subpopulation in particular, were most resistant to the Dex-mediated depletion, thus giving rise to an enrichment of SP (2-fold) and particularly DN subset in the medium- and low-density populations (5-fold) recovered. 3-ABAm, which alone increased the total thymocyte number up to 2-fold, had no effect on the distribution of phenotypic subsets. However, the inhibitor, when given in combination with Dex, additionally depleted all four phenotypic subsets up to one-third of the levels with Dex alone, except for those of medium-density subpopulation. Because the non-inhibitor, 3-aminobenzoate, had no potentiating effect, our present results, together with our previous in vitro studies, indicate a role for the DNA repair cofactor poly ADP-ribose in the intrathymic death by apoptosis and depletion of thymocytes, especially those of DP subset in the high-density, functionally immature population.

Methylation of nicotinamide in rat liver cytosol and its correlation with hepatocellular proliferation.

The changes in the activity of nicotinamide: S-adenosylmethionine methyltransferase (nicotinamide methylase) were studied in rat liver which was subjected to different rates of cellular proliferation. The cytosolic enzyme activity increased 3-4-fold in the first 24-48 h after partial hepatectomy and decreased again to the basal levels until 4 days post-operatively, whereas it remained unchanged in the livers of sham-operated animals. A single administration of thioacetamide at a dose of 50-250 mg/kg body weight, a treatment which induces hepatocellular proliferation as well, also enhanced the enzyme activity 2-3-fold 24 h after drug administration. This activity increase was associated with a marked lowering of intracellular NAD content of as much as 50% of the control levels. D-Galactosamine, a known hepatotoxic agent causing acute hepatitis in experimental animals and preventing DNA synthesis in regenerating liver, blocked the activity increase in regenerating rat liver. The rate of 1-methylnicotinamide synthesis, as measured by incubating liver slices in the culture medium supplemented with [14C]nicotinamide as a precursor, was found to be 2-4 times higher in the slices from regenerating liver and thioacetamide-treated rat liver than those from non-proliferating control liver. These results, together with our previous finding on the enhancement by 1-methylnicotinamide of the growth of cultured rat liver cells (Hoshino, J., Kühne, U. and Kröger, H. (1982) Biochem. Biophys. Res. Commun. 105, 1446-1452), support the view that nicotinamide methylase and its product, 1-methyl-nicotinamide, are involved in the control of hepatocellular DNA synthesis and proliferation.

Inhibitory effect of cortisone acetate on the stimulation of rat liver cytosol L-serrine. Pyruvate aminotransferase by dibutyryl adenosine 3,5-monophosphate.

An injection of cortisone acetate at a dose of 5 mg/100 g body weight concomitant with dibutyryl cyclic AMP prevents the increase in the activity of rat liver cytosol serine aminotransferase (L-serine:pyruvate aminotransferase, EC 2.6.1.51) elicited by the nucleotide with a lag of about 2 h. If the glucocorticoid is given 2 h prior to the nucleotide inducer, the lag disappears. The inhibitory effect of cortisone acetate gradually decays and is no longer detectable 12 h following its administration. Theophylline, insulin and glucose at doses which affect significantly the level of tyrosine aminotransferase, have not effect on the level of serine aminotransferase and on the cortisone inhibition. The inhibitory effect of the glucocorticoid on the dibutyryl cyclic AMP-mediated increase in serin aminotransferase diminishes with the age of animall. Increases in the enzyme activity by a single dose of glucagon can also be inhibited by cortisone acetate and actinomycin D as in the case with dibutyryl cyclic AMP as an inducer. The possibility of the existence of a specific inhibitory factor which is formed in response to cortisone acetate is discussed.

Suppression of nuclear ADP-ribosyltransferase activity in Ehrlich ascites tumor cells by 5-azacytidine. Modification of DNA as a cause of suppression.

Exposure of Ehrlich ascites tumor cells to 5-azacytidine for 5 h resulted in a partial loss of ability of DNA to stimulate ADP-ribosyltransferase activity, as assessed in a reconstituted in vitro enzyme system consisting of purified calf thymus enzyme, calf thymus whole histone and DNA isolated from the cells. The degree of suppression in vitro varied depending on the amount of histone and DNA added and it reached a maximum with a value of 83% and 62% of control for DNAs from cells exposed to 10 microM and 30 microM 5-azacytidine, respectively, at a histone/DNA mass ratio of 0.4. In the absence of histone (conditions of auto-ADP-ribosylation of the enzyme), no suppression was detectable.