Reduction of diabetes-induced oxidative stress, fibrotic cytokine expression, and renal dysfunction in protein kinase Cbeta-null mice

Diabetes induces the activation of several protein kinase C (PKC) isoforms in the renal glomeruli. We used PKC-beta(-/-) mice to examine the action of PKC-beta isoforms in diabetes-induced oxidative stress and renal injury at 8 and 24 weeks of disease. Diabetes increased PKC activity in renal cortex of wild-type mice and was significantly reduced (<50% of wild-type) in diabetic PKC-beta(-/-) mice. In wild-type mice, diabetes increased the translocation of PKC-alpha and -beta1 to the membrane, whereas only PKC-alpha was elevated in PKC-beta(-/-) mice. Increases in urinary isoprostane and 8-hydroxydeoxyguanosine, parameters of oxidative stress, in diabetic PKC-beta(-/-) mice were significantly reduced compared with diabetic wild-type mice. Diabetes increased NADPH oxidase activity and the expressions of p47(phox), Nox2, and Nox4 mRNA levels in the renal cortex and were unchanged in diabetic PKC-beta(-/-) mice. Increased expression of endothelin-1 (ET-1), vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-beta, connective tissue growth factor (CTGF), and collagens IV and VI found in diabetic wild-type mice was attenuated in diabetic PKC-beta(-/-) mice. Diabetic PKC-beta(-/-) mice were protected from renal hypertrophy, glomerular enlargement, and hyperfiltration observed in diabetic wild-type mice and had less proteinuria. Lack of PKC-beta can protect against diabetes-induced renal dysfunction, fibrosis, and increased expressions of Nox2 and -4, ET-1, VEGF, TGF-beta, CTGF, and oxidant production.

Silent information regulator 2 (SIRT1) attenuates oxidative stress-induced mesangial cell apoptosis via p53 deacetylation

Oxidative stress-induced apoptosis of renal glomerular cells is an important factor for the development of various kidney diseases. Identification of molecules that modulate this process could lead to the development of new strategies for preventing kidney diseases. In this study, we evaluated whether mammalian silent information regulator 2 (SIRT1), which has been recently identified as a cell survival factor countering various stressors, is a key regulator of oxidative stress-induced mesangial cell apoptosis. Morphological features of apoptotic cell death (nuclear condensation) and the expression of biochemical proapoptotic markers [cleavages of caspase-3 and poly (ADP-ribose) polymerase (PARP)] were assessed in murine mesangial cells (MMCs) exposed to hydrogen peroxide (H(2)O(2)). H(2)O(2) increased mesangial cell apoptosis, predominantly through p53 activation by acetylation, which is a posttranscriptional modification for p53 activation. H(2)O(2)-induced apoptosis was significantly attenuated in SIRT1-overexpressing MMCs, but enhanced in SIRT1-knockdown MMCs. Although SIRT1 did not affect H(2)O(2)-mediated phosphorylation of mitogen-activated protein (MAP) kinase, it interacted with p53 and inhibited H(2)O(2)-mediated p53 acetylation but not phosphorylation in MMCs. Our results indicate that SIRT1 can prevent oxidative stress-induced apoptosis through p53 deacetylation in mesangial cells. Upregulation of SIRT1 may provide a new strategy for preventing kidney glomerular diseases.

Polymorphisms of the protein kinase C-beta gene (PRKCB1) accelerate kidney disease in type 2 diabetes without overt proteinuria

OBJECTIVE

We investigated the contribution of PKC-beta gene (PRKCB1) polymorphisms to diabetic kidney disease in a prospective observational follow-up study.

RESEARCH DESIGN AND METHODS

A total of 364 Japanese subjects with type 2 diabetes without overt proteinuria were enrolled during 1996-1998 and followed until 2004. Five single nucleotide polymorphisms (-1504C/T, -546C/G, -348A/G, -278C/T, and -238C/G) in the promoter region of PRKCB1 were genotyped. The end points were transition from stage to stage of diabetic nephropathy as a time-to-event outcome and the annual decline rate of estimated glomerular filtration rate (eGFR) as a slope-based outcome.

RESULTS

During the study (median 6 years), 34 of 364 subjects (9.3%) progressed. Kaplan-Meier estimation revealed that subjects with both T allele at -1054 C/T and G allele at -546 C/G polymorphisms frequently showed transition to advanced stages of diabetic nephropathy (P = 0.015). The annual change rate in eGFR in the subjects with both alleles was also significantly higher than in others (-2.96 +/- 0.62 vs. -1.63 +/- 0.15 ml/min per 1.73 m(2)/year, P = 0.02). The estimated frequency of this risk T-G haplotype was significantly higher in the progressors who showed transition to advanced nephropathy stages (12%) than in the nonprogressors (5%) (odds ratio 2.3 [95% CI 1.0-5.2]), and it was also higher in those with accelerated decline of the Delta eGFR (> or =3 ml/min per 1.73 m(2)/year) than in those without (2.1 [1.1-3.9]).

CONCLUSIONS

Our study indicates that PRKCB1 is a predictor for worsening of kidney disease in Japanese subjects with type 2 diabetes.

N-acetyl-seryl-aspartyl-lysyl-proline inhibits DNA synthesis in human mesangial cells via up-regulation of cell cycle modulators

N-Acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) was originally reported as a natural inhibitor of the proliferation of stem cells. To elucidate whether Ac-SDKP inhibits the proliferation of human mesangial cells, we examined the effect of Ac-SDKP on fetal calf serum (FCS)- or platelet-derived growth factor (PDGF)-BB-induced DNA synthesis and a cell proliferation. Ac-SDKP inhibited PDGF-BB- or FCS-induced DNA synthesis without cellular toxicity. The protein expression of p53 and p27kip1 was significantly increased by Ac-SDKP. Ac-SDKP also up-regulated the PDGF-BB-stimulated expression of p21cip1 and suppressed PDGF-BB-induced cyclin D1 expression. In p53 knock-out human mesangial cells made with small interference RNA, the protein expression of p21cip1 and p27kip1 was also decreased and the inhibitory effect of Ac-SDKP on mesangial proliferation was completely abolished. Ac-SDKP increased the stability of p53 protein as demonstrated by pulse-chase experiment. These results suggest that p53 is the key mediator of Ac-SDKP-induced inhibition of DNA synthesis through the up-regulation of cell cycle modulators, highlighting a potential effect of Ac-SDKP on various progressive renal diseases.

Systemic cholesterol embolization syndrome associated with myeloperoxidase-anti-neutrophil cytoplasmic antibody

A 75-year-old man was transferred to our department because of development of severe renal impairment after coronary artery bypass grafting. Hemodialysis was initiated for postsurgical oliguria and lung congestion. On transfer, he showed systemic purpura rashes and diffuse blue mottlings on his toes with marked eosinophilia and an elevated level of C-reactive protein. Cutaneous biopsy revealed cholesterol crystal embolism and leukocytoclastic vasculitis in dermal arterioles. Myeloperoxidase-anti-neutrophil cytoplasmic antibody titer was increased. Upon oral corticosteroid therapy following intravenous pulse steroid therapy, the purpura dramatically diminished, renal function improved, and hemodialysis was discontinued. Active treatment with corticosteroids may be effective for cholesterol embolization syndrome, particularly when clinical and laboratory manifestations mimic systemic vasculitis.

Inhibition of mTOR signaling with rapamycin attenuates renal hypertrophy in the early diabetic mice

Early diabetic nephropathy is characterized by renal hypertrophy that is mainly due to proximal tubular hypertrophy. Mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase, and its signaling has been reported to regulate protein synthesis and cellular growth, specifically, hypertrophy. Therefore, we examined the effect of mTOR signaling on diabetic renal hypertrophy by using the specific inhibitor for mTOR, rapamycin. Ten days after streptozotocin-induced diabetes, mice showed kidney hypertrophy with increases in the phosphorylation of p70S6kinase and the expression of cyclin kinase inhibitors, p21(Cip1) and p27(Kip1), in the kidneys. The intraperitoneal injection of rapamycin (2 mg/kg/day) markedly attenuated the enhanced phosphorylation of p70S6kinase, the increment of cyclin-dependent kinase inhibitors, and renal enlargement without any changes of clinical parameters, including blood glucose, blood pressure, and food intake. Overexpression of a constitutive active form of p70S6kinase resulted in increased cell size of cultured mouse proximal tubule cells; thus, activation of p70S6kinase causes hypertrophy of proximal tubular cells. Our findings suggest that activation of mTOR signaling causes renal hypertrophy at the early stage of diabetes.

Factors associated with frequent remission of microalbuminuria in patients with type 2 diabetes

To estimate the frequency of remission/regression of microalbuminuria and to identify factors affecting such outcomes in Japanese patients with type 2 diabetes, we observed 216 patients with type 2 diabetes and microalbuminuria enrolled during an initial 2-year evaluation period for the next 6 years. Remission was defined as shift to normoalbuminuria and regression as a 50% reduction in urinary albumin excretion rate (AER) from one 2-year period to the next. Reduction of urinary AER was frequent, with a 6-year cumulative incidence of 51% (95% CI 42-60) for remission and 54% (45-63) for regression, whereas the frequency of progression to overt proteinuria was 28% (19-37). Microalbuminuria of short duration, the use of renin-angiotensin system-blocking drugs, and lower tertiles for HbA(1c) (<6.95%) and systolic blood pressure (<129 mmHg) were independently associated with remission or regression in the pooled logistic regression analysis. The results indicate that reduction in urinary AER occurs frequently in Japanese patients with type 2 diabetes. Early detection of microalbuminuria and a multifactorial control may result in improved outcomes for diabetic nephropathy and cardiovascular events.

Use of hydrogen peroxide in combination with nisin, sodium lactate and citric acid for reducing transfer of bacterial pathogens from whole melon surfaces to fresh-cut pieces

Hydrogen peroxide (2.5%) alone or hydrogen peroxide (1%) in combination with nisin (25 microg/ml), sodium lactate (1%), and citric acid (0.5%) (HPLNC) were investigated as potential sanitizers for reducing Escherichia coli O157:H7 or Listeria monocytogenes populations on whole cantaloupe and honeydew melons. Whole cantaloupes inoculated with E. coli O157:H7 and L. monocytogenes at 5.27 and 4.07 log10 CFU/cm2, respectively, and whole honeydew melons inoculated with E. coli O157:H7 and L. monocytogenes at 3.45 and 3.05 log10 CFU/cm2, respectively, were stored at 5 degrees C for 7 days. Antimicrobial washing treatments were applied to inoculated whole melons on days 0 or 7 of storage and surviving bacterial populations and the numbers transferred to fresh-cut pieces were determined. At days 0 and 7 treatment with HPLNC significantly (p<0.05) reduced the numbers of both pathogens, by 3 to 4 log CFU/cm2 on both types of whole melon. Treatment with HPLNC was significantly (p<0.05) more effective than treatment with 2.5% hydrogen peroxide. While fresh-cut pieces prepared from stored whole melons were negative for the pathogens by both direct plating and by enrichment, fresh-cut pieces from cantaloupe melons treated with 2.5% hydrogen peroxide were positive for both pathogens and pieces from honeydew melons were positive for E. coli 0157:H7. The native microflora on fresh-cut melons were also substantially reduced by HPLNC treatment of whole melons. The results suggest that HPLNC could be used to decontaminate whole melon surfaces and so improve the microbial safety and quality of fresh-cut melons.

Estrogen and raloxifene, a selective estrogen receptor modulator, ameliorate renal damage in db/db mice

Despite the potentially protective effects of estrogen on bone and cardiovascular tissue as well as against kidney diseases, its effects on diabetic nephropathy are unknown. Here, we examined the therapeutic effectiveness of 17beta-estradiol and raloxifene, a selective estrogen receptor modulator, for preventing functional and histological alterations in the kidneys of db/db mice, a model of type 2 diabetes. In the first experiment, ovariectomized female db/db mice were treated with 17beta-estradiol for 8 weeks. The treatment significantly ameliorated albuminuria, attenuated weight gain, and reduced hyperglycemia in diabetic ovariectomized db/db mice. Histologically, the increases in mesangial area and the accumulation of fibronectin were significantly inhibited by 17beta-estradiol. In the second experiment, mice were administered vehicle or raloxifene hydrochloride (3 mg/kg/day) for 8 weeks. Raloxifene significantly reduced mesangial expansion and fibronectin accumulation in db/db mice, but in contrast to 17beta-estradiol, it failed to affect body weight or hyperglycemia. An in vitro experiment further demonstrated that raloxifene inhibited transforming growth factor beta-1-induced fibronectin transcription and AP-1 activity. Thus, our findings suggest that raloxifene, which lacks the harmful effects of estrogen, is useful for the treatment of diabetic nephropathy.

Combined efficacy of nisin and pediocin with sodium lactate, citric acid, phytic acid, and potassium sorbate and EDTA in reducing the Listeria monocytogenes population of inoculated fresh-cut produce

The inability of chlorine to completely inactivate human bacterial pathogens on whole and fresh-cut produce suggests a need for other antimicrobial washing treatments. Nisin (50 microg/ml) and pediocin (100 AU/ml) individually or in combination with sodium lactate (2%), potassium sorbate (0.02%), phytic acid (0.02%), and citric acid (10 mM) were tested as possible sanitizer treatments for reducing the population of Listeria monocytogenes on cabbage, broccoli, and mung bean sprouts. Cabbage, broccoli, and mung bean sprouts were inoculated with a five-strain cocktail of L. monocytogenes at 4.61, 4.34, and 4.67 log CFU/g, respectively. Inoculated produce was left at room temperature (25 degrees C) for up to 4 h before antimicrobial treatment. Washing treatments were applied to inoculated produce for 1 min, and surviving bacterial populations were determined. When tested alone, all compounds resulted in 2.20- to 4.35-log reductions of L. monocytogenes on mung bean, cabbage, and broccoli, respectively. The combination treatments nisin-phytic acid and nisin-pediocin-phytic acid caused significant (P < 0.05) reductions of L. monocytogenes on cabbage and broccoli but not on mung bean sprouts. Pediocin treatment alone or in combination with any of the organic acid tested was more effective in reducing L. monocytogenes populations than the nisin treatment alone. Although none of the combination treatments completely eliminated the pathogen on the produce, the results suggest that some of the treatments evaluated in this study can be used to improve the microbial safety of fresh-cut cabbage, broccoli, and mung bean sprouts.

N-acetyl-seryl-aspartyl-lysyl-proline prevents renal insufficiency and mesangial matrix expansion in diabetic db/db mice

We have previously reported that N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), which is a tetrapeptide hydrolyzed by ACE, inhibits the transforming growth factor-beta (TGF-beta)-induced expression of extracellular matrix proteins via inhibition of the Smad signaling in human mesangial cells. To test in vivo the antifibrotic efficacy of Ac-SDKP, we examined whether long-term Ac-SDKP treatment can prevent renal insufficiency and glomerulosclerosis in diabetic db/db mice. Diabetic db/db mice or nondiabetic db/m mice were treated with Ac-SDKP for 8 weeks using osmotic minipumps. The treatment with Ac-SDKP increased plasma Ac-SDKP concentrations by approximately threefold in both groups but did not affect the blood glucose levels. Histologically, the increased glomerular surface area, mesangial matrix expansion, and overproduction of extracellular matrix proteins in db/db mice were significantly inhibited by Ac-SDKP. Furthermore, Ac-SDKP treatment normalized the increased plasma creatinine value in db/db mice, whereas the albuminuria in Ac-SDKP-treated db/db mice was somewhat decreased as compared with nontreated db/db mice, although the difference was not statistically significant. In addition, the nuclear translocation of Smad3 was inhibited by Ac-SDKP. These results demonstrate that long-term Ac-SDKP treatment ameliorates renal insufficiency and glomerulosclerosis in db/db mice via inhibition of TGF-beta/Smad pathway, suggesting that Ac-SDKP could be useful in the treatment of diabetic nephropathy.

Differential regulation of angiotensin II-induced expression of connective tissue growth factor by protein kinase C isoforms in the myocardium

Protein kinase C (PKC) and angiotensin II (AngII) can regulate cardiac function in pathological conditions such as in diabetes or ischemic heart disease. We have reported that expression of connective tissue growth factor (CTGF) is increased in the myocardium of diabetic mice. Now we showed that the increase in CTGF expression in cardiac tissues of streptozotocin-induced diabetic rats was reversed by captopril and islet cell transplantation. Infusion of AngII in rats increased CTGF mRNA expression by 15-fold, which was completely inhibited by co-infusion with AT1 receptor antagonist, candesartan. Similarly, incubation of cultured cardiomyocytes with AngII increased CTGF mRNA expression by 2-fold, which was blocked by candesartan and a general PKC inhibitor, GF109203X. The role of PKC isoform-dependent action was further studied using adenoviral vector-mediated gene transfer of dominant negative (dn) PKC or wild type PKC isoforms. Expression of dnPKCalpha, -epsilon, and -zeta isoforms suppressed AngII-induced CTGF expression in cardiomyocytes. In contrast, expression of dominant negative PKCdelta significantly increased AngII-induced CTGF expression, whereas expression of wild type PKCdelta inhibited this induction. This inhibitory effect was further confirmed in the myocardium of transgenic mice with cardiomyocyte-specific overexpression of PKCdelta (deltaTg mice). Thus, AngII can regulate CTGF expression in cardiomyocytes through a PKC activation-mediated pathway in an isoform-selective manner both in physiological and diabetic states and may contribute to the development of cardiac fibrosis in diabetic cardiomyopathy.

Effectiveness of irradiation treatments in inactivating Listeria monocytogenes on fresh vegetables at refrigeration temperature

Ionizing radiation can be effective in controlling the growth of food spoilage and foodborne pathogenic bacteria. This study reports on an investigation of the effectiveness of irradiation treatment to eliminate Listeria monocytogenes on laboratory-inoculated broccoli, cabbage, tomatoes, and mung bean sprouts. Irradiation of broccoli and mung bean sprouts at 1.0 kGy resulted in reductions of approximately 4.88 and 4.57 log CFU/g, respectively, of a five-strain cocktail of L. monocytogenes. Reductions of approximately 5.25 and 4.14 log CFU/g were found with cabbage and tomato, respectively, at a similar dose. The appearance, color, texture, taste, and overall acceptability did not undergo significant changes after 7 days of postirradiation storage at 4 degrees C, in comparison with control samples. Therefore, low-dose ionizing radiation treatment could be an effective method for eliminating L. monocytogenes on fresh and fresh-cut produce.

Development of a novel microbial sensor with baker's yeast cells for monitoring temperature control during cold food chain

A novel microbial sensor containing a commercial baker's yeast with a high freeze tolerance was developed for visibly detecting inappropriate temperature control of food. When the yeast cells fermented glucose, the resulting gas production triggered the microbial sensor. The biosensor was a simple, small bag containing a solution of yeast cells, yeast extract, glucose, and glycerol sealed up with multilayer transparent film with barriers against oxygen and humidity. Fine adjustment of gas productivity in the biosensor at low temperatures was achieved by changing either or both concentrations of glucose and yeast cells. Moreover, the amount of time that food was exposed to inappropriate temperatures could be deduced by the amount of gas produced in the biosensor. The biosensor was stable without any functional loss for up to 1 week in frozen storage. The biosensor could offer a useful tool for securing food safety by maintaining low-temperature control in every stage from farm to fork, including during transportation, in the store, and at home.

[Case of autosomal dominant polycystic kidney disease associated with congenital hepatic fibrosis]

A 31-year-old man was admitted to the hospital because of a low-grade fever, general malaise, nausea, vomiting, and a poor appetite. On admission his renal function was severely deteriorated (serum creatinine 16.12 mg/dl, BUN 163 mg/dl), and he had severe anemia (Hb 7.5 g/dl) and thrombocytopenia (67,000/microl). A radiological examination revealed the presence of multiple cysts in his kidneys bilaterally. The patient was diagnosed as having end-stage renal disease due to polycystic kidney disease, and hemodialysis was started on the day of admission. After the initiation of hemodialysis, his symptoms and laboratory tests improved, except for anemia and thrombocytopenia. He was noted to have marked splenomegaly and dilation of the portal vein, raising the suspicion of portal hypertension as the cause of the splenomegaly and pancytopenia. To treat his pancytopenia (anemia and thrombocytopenia) and to determine the reason for his portal hypertension, a splenectomy and open-wedge biopsy of the liver were performed. Histological findings in the liver included extensive fibrosis of the portal areas with an excess of moderately dilated bile ducts, compatible with a diagnosis of congenital hepatic fibrosis. After splenectomy, his red blood cell and platelet counts returned to normal, and he was discharged on maintenance dialysis. Congenital hepatic fibrosis is often associated with autosomal recessive polycystic kidney disease (ARPKD), but not with autosomal dominant polycystic kidney disease (ADPKD). However, both his mother and older brother had multiple renal cysts, indicating that this was an unusual case of ADPKD complicated by congenital hepatic fibrosis.

Menadione-catalyzed luminol chemiluminescence assay for the rapid detection of viable bacteria in foods under aerobic conditions

A menadione-catalyzed luminol chemiluminescence assay was developed for the rapid detection and estimation of viable bacteria in foods. The principle of this assay is based on the extracellular menadione-catalyzed active oxygen spieces (O2- and H2O2) generated by the activity of NAD(P)H:menadione oxidoreductase in viable cells. This luminol chemiluminescence assay requires 10 min for the incubation of cells with menadione and then 2 s for the measurement of chemiluminescence intensity after an injection of luminol solution without the treatment of cell lysis. This method was evaluated using liquid food samples of milk, vegetable juice, green tea, and coffee spiked with Escherichia coli ATCC 25922. The study result revealed that E. coli contamination at 1 to 10 CFU/ml in these foods could be detected after incubation at 37 degrees C for 7 h in an enrichment medium; however, the green tea and coffee samples requires filtration. This method could be a useful tool for the rapid evaluation of microbial food contamination.

Survival of Escherichia coli O157:H7, Salmonella enteritidis, Staphylococcus aureus, and Listeria monocytogenes in Kimchi

The survival of gram-positive and gram-negative foodborne pathogens in both commercial and laboratory-prepared kimchi (a traditional fermented food widely consumed in Japan) was investigated. It was found that Escherichia coli O157:H7, Salmonella Enteritidis, Staphylococcus aureus, and Listeria monocytogenes could survive in both commercial and laboratory-prepared kimchi inoculated with these pathogens and incubated at 10 degrees C for 7 days. However, when incubation was prolonged, the S. aureus level decreased rapidly from the initial inoculum level to the minimum detectable level within 12 days, whereas Salmonella Enteritidis and L. monocytogenes took 16 days to reach similar levels in commercial kimchi. On the other hand, E. coli O157:H7 remained at high levels throughout the incubation period. For laboratory-prepared kimchi, the S. aureus level decreased rapidly from the initial inoculum level to the minimum detectable level within 12 days, and L. monocytogenes took 20 days to reach a similar level. E. coli O157:H7 and Salmonella Enteritidis remained at high levels throughout the incubation period. The results of this study suggest that the contamination of kimchi with E. coli O157:H7, Salmonella Enteritidis, S. aureus, or L. monocytogenes at any stage of production or marketing could pose a potential risk.

Chemical and irradiation treatments for killing Escherichia coli O157:H7 on alfalfa, radish, and mung bean seeds

In this study, the effectiveness of dry-heat treatment in combination with chemical treatments (electrolyzed oxidizing [EO] water, califresh-S, 200 ppm of active chlorinated water) with and without sonication in eliminating Escherichia coli O157:H7 on laboratory-inoculated alfalfa, radish, and mung bean seeds was compared with that of dry-heat treatment in combination with irradiation treatment. The treatment of mung bean seeds with EO water in combination with sonication followed by a rinse with sterile distilled water resulted in reductions of approximately 4.0 log10 CFU of E. coli O157:H7 per g. whereas reductions of ca. 1.52 and 2.64 log10 CFU/g were obtained for radish and alfalfa seeds. The maximum reduction (3.70 log10 CFU/g) for mung bean seeds was achieved by treatment with califresh-S and chlorinated water (200 ppm) in combination with sonication and a rinse. The combination of dry heat, hot EO water treatment, and sonication was able to eliminate pathogen populations on mung bean seeds but was unable to eliminate the pathogen on radish and alfalfa seeds. Other chemical treatments used were effective in greatly reducing pathogen populations on radish and alfalfa seeds without compromising the quality of the sprouts, but these treatments did not result in the elimination of pathogens from radish and alfalfa seeds. Moreover, a combination of dry-heat and irradiation treatments was effective in eliminating E. coli O157:H7 on laboratory-inoculated alfalfa, radish, and mung bean seeds. An irradiation dose of 2.0 kGy in combination with dry heat eliminated E. coli O157:H7 completely from alfalfa and mung bean seeds, whereas a 2.5-kGy dose of irradiation was required to eliminate the pathogen completely from radish seeds. Dry heat in combination with irradiation doses of up to 2.0 kGy did not unacceptably decrease the germination percentage for alfalfa seeds or the length of alfalfa sprouts but did decrease the lengths of radish and mung bean sprouts.

Effectiveness of electrolyzed acidic water in killing Escherichia coli O157:H7, Salmonella enteritidis, and Listeria monocytogenes on the surfaces of tomatoes

A study was conducted to evaluate the efficacy of electrolyzed acidic water, 200-ppm chlorine water, and sterile distilled water in killing Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on the surfaces of spot-inoculated tomatoes. Inoculated tomatoes were sprayed with electrolyzed acidic water, 200-ppm chlorine water, and sterile distilled water (control) and rubbed by hand for 40 s. Populations of E. coli O157:H7, Salmonella, and L. monocytogenes in the rinse water and in the peptone wash solution were determined. Treatment with 200-ppm chlorine water and electrolyzed acidic water resulted in 4.87- and 7.85-log10 reductions, respectively, in Escherichia coli O157:H7 counts and 4.69- and 7.46-log10 reductions, respectively, in Salmonella counts. Treatment with 200-ppm chlorine water and electrolyzed acidic water reduced the number of L. monocytogenes by 4.76 and 7.54 log10 CFU per tomato, respectively. This study's findings suggest that electrolyzed acidic water could be useful in controlling pathogenic microorganisms on fresh produce.

Role of protein kinase C on the expression of platelet-derived growth factor and endothelin-1 in the retina of diabetic rats and cultured retinal capillary pericytes

Increased expression of endothelin-1 (ET-1) is associated with diabetic retinopathy and vasculopathy, although the molecular explanation has not been defined. The effects of high glucose and protein kinase C (PKC) activation on platelet-derived growth factor (PDGF)-BB and of ET-1 expression in the retina of streptozotocin (STZ)-induced diabetic rats and bovine retinal pericytes (BRPC) were examined. In 4-week diabetic rats, PDGF-B and prepro-ET-1 (ppET-1) mRNA levels increased significantly by 2.8- and 1.9-fold, respectively, as quantified by RT-PCR. Treatment with PKC-beta isoform-specific inhibitor (LY333531) or insulin normalized retinal ET-1 and PDGF-B expression. In BRPC, high glucose levels increased ppET-1 and PDGF-B mRNA expression by 1.7- and 1.9-fold, respectively. The addition of PDGF-BB but not PDGF-AA increased expression of ppET-1 and vascular endothelial growth factor mRNA by 1.6- and 2.1-fold, respectively, with both inhibited by AG1296, a selective PDGF receptor kinase inhibitor. A general PKC inhibitor, GF109203X, suppressed PDGF-BB's induction of ET-1 mRNA. Thus, increased ET-1 expression in diabetic retina could be due to increased expression of PDGF-BB, mediated via PDGF-beta receptors in part by PKC activation. The novel demonstration of elevated expression of PDGF-B and its induction by PKC activation identifies a potential new molecular step in the pathogenesis of diabetic retinopathy.

Calcinated calcium killing of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on the surface of tomatoes

This study was conducted to evaluate the efficacy of calcinated calcium, 200 ppm chlorine water (1% active chlorine), and sterile distilled water in killing Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on the surfaces of spot-inoculated tomatoes. Inoculated tomatoes were sprayed with calcinated calcium, chlorinated water, or sterile distilled water (control) and hand rubbed for 30 s. Populations of E coli O157:H7, Salmonella, and L. monocytogenes in the rinse water and in the residual (0.1% peptone) wash solution were determined. Treatment with 200 ppm chlorine and calcinated calcium resulted in 3.40- and 7.85-log10 reductions of E. coli O157:H7, respectively, and 2.07- and 7.36-log10 reductions of Salmonella, respectively. Treatment with 200 ppm chlorine and calcinated calcium reduced L monocytogenes numbers by 2.27 and 7.59 log10 CFU per tomato, respectively. The findings of this study suggest that calcinated calcium could be useful in controlling pathogenic microorganisms in fresh produce.

Expression of connective tissue growth factor is increased in injured myocardium associated with protein kinase C beta2 activation and diabetes

Protein kinase C (PKC) beta isoform activity is increased in myocardium of diabetic rodents and heart failure patients. Transgenic mice overexpressing PKCbeta2 (PKCbeta2Tg) in the myocardium exhibit cardiomyopathy and cardiac fibrosis. In this study, we characterized the expression of connective tissue growth factor (CTGF) and transforming growth factor beta (TGFbeta) with the development of fibrosis in heart from PKCbeta2Tg mice at 4-16 weeks of age. Heart-to-body weight ratios of transgenic mice increased at 8 and 12 weeks, indicating hypertrophy, and ratios did not differ at 16 weeks. Collagen VI and fibronectin mRNA expression increased in PKCbeta2Tg hearts at 4-12 weeks. Histological examination revealed myocyte hypertrophy and fibrosis in 4- to 16-week PKCbeta2Tg hearts. CTGF expression increased in PKCbeta2Tg hearts at all ages, whereas TGFbeta increased only at 8 and 12 weeks. In 8-week diabetic mouse heart, CTGF and TGFbeta expression increased two- and fourfold, respectively. Similarly, CTGF expression increased in rat hearts at 2-8 weeks of diabetes. This is the first report of increased CTGF expression in myocardium of diabetic rodents suggesting that cardiac injury associated with PKCbeta2 activation, diabetes, or heart failure is marked by increased CTGF expression. CTGF could act independently or together with other cytokines to induce cardiac fibrosis and dysfunction.