Incident Cancer Risk in Patients with Incident Type 2 Diabetes Mellitus in Hungary (Part 1).

(1) Background: Patients with type 2 diabetes mellitus (T2DM) are at higher risk of cancer but how these two diseases associate is still debated. The goal of this study was the assessment of the overall incidence of cancer among patients with newly diagnosed T2DM in Hungary. (2) Methods: A nationwide, retrospective, longitudinal study was performed using a Hungarian database. After exclusion of cases of age < 18 years, with gestational diabetes, with polycystic ovary syndrome, and with type 1 and prevalent type 2 diabetes mellitus, the incident T2DM (approx. 50,000 cases yearly) and for comparison, the diabetes-free Hungarian adult population (approx. 7,000,000 cases yearly) was included in the study. The primary endpoints were the overall and site-specific incidence and annual percentage change of the incidence of cancer in both populations. (3) Results: The overall incidence of cancer in patients amounted to 29.4/1000 and 6.6/1000 with or without T2DM, respectively, and the OR (95%CI) of cancer of the T2DM group was 4.32 (4.14-4.53), p < 0.0001. The risk of having cancer was age dependent. The incidence of cancer was declining in the non-diabetic but was unchanged in the T2DM population. The average lag time of diagnosing cancer after the detection of T2DM was 3.86 months. (4) Conclusions: Incident T2DM is associated with a significantly higher overall risk of incident cancer, with a reverse correlation of age. Newly registered T2DM patients were suggested to be screened for cancer within 6 months.

Effectiveness of SARS-CoV-2 primary vaccines and boosters in patients with type 2 diabetes mellitus in Hungary (HUN-VE 4 Study).

INTRODUCTION: Type 2 diabetes mellitus is a risk factor for severe COVID-19 infection and is associated with increased risk of complications. The present study aimed to investigate effectiveness and persistence of different COVID vaccines in persons with or without diabetes during the Delta wave in Hungary. RESEARCH DESIGN AND METHODS: Data sources were the national COVID-19 registry data from the National Public Health Center and the National Health Insurance Fund on the total Hungarian population. The adjusted incidence rate ratios and corresponding 95% CIs were derived from a mixed-effect negative binomial regression model. RESULTS: A population of 672 240 cases with type 2 diabetes and a control group of 2 974 102 non-diabetic persons free from chronic diseases participated. Unvaccinated elderly persons with diabetes had 2.68 (95% CI 2.47 to 2.91) times higher COVID-19-related mortality rate as the 'healthy' controls. Primary immunization effectively equalized the risk of COVID-19 mortality between the two groups. Vaccine effectiveness declined over time, but the booster restored the effectiveness against mortality to over 90%. The adjusted vaccine effectiveness of the primary Pfizer-BioNTech against infection in the 14-120 days of postvaccination period was 71.6 (95% CI 66.3 to 76.1)% in patients aged 65-100 years with type 2 diabetes and 64.52 (95% CI 59.2 to 69.2)% in the controls. Overall, the effectiveness tended to be higher in individuals with diabetes than in controls. The booster vaccines could restore vaccine effectiveness to over 80% concerning risk of infection (eg, patients with diabetes aged 65-100 years: 89.1 (88.1-89.9)% with Pfizer-on-Pfizer, controls 65-100 years old: 86.9 (85.8-88.0)% with Pfizer-on-Pfizer, or patients with diabetes aged 65-100 years: 88.3 (87.2-89.2)% with Pfizer-on-Sinopharm, controls 65-100 years old: 87.8 (86.8-88.7)% with Pfizer-on-Sinopharm). CONCLUSIONS: Our data suggest that people with type 2 diabetes may have even higher health gain when getting vaccinated as compared with non-diabetic persons, eliminating the marked, COVID-19-related excess risk of this population. Boosters could restore protection.

Plasma Levels and Renal Handling of Amino Acids Contribute to Determination of Risk of Mortality or Feed of Ventilation in Patients with COVID-19.

COVID-19 infection may lead to serious complications, e.g., need for mechanical ventilation or death in some cases. A retrospective analysis of patients referred to our COVID Emergency Department, indiscriminately, was performed. A routine lab analysis measured amino acids in plasma and urine of patients. Data of surviving and deceased patients and those requiring or not requiring mechanical ventilation were compared, and logistic regression analyses have been performed. Deceased patients were older, had higher blood glucose, potassium, AST, LDH, troponin, d-dimer, hsCRP, procalcitonin, interleukin-6 levels (p < 0.05 for all). They had lower plasma serine, glycine, threonine, tryptophan levels (p < 0.01), higher tyrosine and phenylalanine levels (p < 0.05), and higher fractional excretion of arginine, methionine, and proline (p < 0.05) than survivors. In a regression model, age, severity score of COVID-pneumonia, plasma levels of threonine and phenylalanine were predictors of in-hospital mortality. There was a difference in ventilated vs. non-ventilated patients in CT-scores, glucose, and renal function (p < 0.001). Using logistic regression, CT-score, troponin, plasma level, and fractional excretion of glycine were predictors of ventilation. Plasma levels and renal excretion of certain amino acids are associated with the outcome of COVID-19 infection beside other parameters such as the CT-score or age.

Risk of morbidity and mortality in patients with type 2 diabetes treated with sodium-glucose cotransporter-2 inhibitor and/or dipeptidyl peptidase-4 inhibitor: a nationwide study.

INTRODUCTION: Mortality and disability in diabetes mellitus are determined mostly by cardiovascular complications and cancer. The impact of dipeptidyl peptidase-4 inhibitor (DPP-4i) and sodium-glucose cotransporter-2 inhibitor (SGLT2i) monotherapy or combination on long-term complications of type 2 diabetes mellitus was studied. RESEARCH DESIGN AND METHODS: Patients with type 2 diabetes treated with DPP-4i or SGLT2i during a 3-year period were identified in the database of the National Institute of Health Insurance Fund in Hungary. All-cause mortality, acute myocardial infarction, stroke, hospitalization for heart failure (HHF), lower limb amputation (LLA) and cancer were assessed. Outcomes of add-on SGLT2i to DPP-4i treatment in comparison with switching DPP-4i therapy to SGLT2i were also evaluated. After propensity score matching, survival analysis was performed with a Cox proportional hazards model. RESULTS: After propensity score matching, both SGLT2i and DPP-4i groups included 18 583 patients. All-cause mortality (HR, 0.80; 95% CI 0.68 to 0.94; p=0.0057), HHF (HR, 0.81; 95% CI 0.71 to 0.92; p=0.0018), and risk of cancer (HR, 0.75; 95% CI 0.66 to 0.86; p<0.0001) were lower in the SGLT2i population compared with DPP-4i. Risk of LLA was higher in the SGLT2i group (HR, 1.35; 95% CI 1.03 to 1.77; p=0.0315). SGLT2i in combination with DPP-4i results in lower all-cause mortality (HR, 0.46; 95% CI 0.31 to 0.67; p=0.0001), with a lower trend in stroke, LLA, HHF and cancer, but without any statistical difference. CONCLUSIONS: SGLT2i treatment leads to a lower risk of overall mortality, HHF and cancer when compared with DPP-4i treatment. Adding SGLT2i to DPP-4i instead of switching from DPP-4i to SGLT2i further lowers the risk of all-cause mortality.

Changes of para-, meta- and ortho-tyrosine over time in burned patients.

PURPOSE: Serious burn injury leads to oxidative stress resulting in production of meta- and ortho-tyrosine, while para-tyrosine is the physiological isoform. Our aim was to investigate the metabolism of these tyrosine isoforms following major burn injury. METHODS: Fifteen patients requiring intensive care were followed for 5 consecutive days after major burn injury. Serum and urine concentrations of para-, meta-, and ortho-tyrosine were measured with high performance liquid chromatography. Fifteen healthy matching individuals were invited as control group. RESULTS: Median serum concentration of normal isoform para-tyrosine decreased in burned patients between days 2 and 5 (p < 0.01). Mean meta-, and ortho-tyrosine levels were significantly higher in patients compared to controls in the same time period (p < 0.05). Renal excretion of para-tyrosine increased significantly in our observation period (p < 0.01). CONCLUSIONS: Pathologic isoforms of tyrosine accumulate in serum meanwhile the level of normal isoform decreases possibly due to belated enhanced renal excretion or, to decreased synthesis after major burn injury.

Role of Tyrosine Isomers in Acute and Chronic Diseases Leading to Oxidative Stress - A Review.

Oxidative stress plays a major role in the pathogenesis of a variety of acute and chronic diseases. Measurement of the oxidative stress-related end products may be performed, e.g. that of structural isomers of the physiological para-tyrosine, namely meta- and ortho-tyrosine, that are oxidized derivatives of phenylalanine. Recent data suggest that in sepsis, serum level of meta-tyrosine increases, which peaks on the 2(nd) and 3(rd) days (p<0.05 vs. controls), and the kinetics follows the intensity of the systemic inflammation correlating with serum procalcitonin levels. In a similar study subset, urinary meta-tyrosine excretion correlated with both need of daily insulin dose and the insulin-glucose product in non-diabetic septic cases (p<0.01 for both). Using linear regression model, meta-tyrosine excretion, urinary meta-tyrosine/para-tyrosine, urinary ortho-tyrosine/para-tyrosine and urinary (meta- + orthotyrosine)/ para-tyrosine proved to be markers of carbohydrate homeostasis. In a chronic rodent model, we tried to compensate the abnormal tyrosine isomers using para-tyrosine, the physiological amino acid. Rats were fed a standard high cholesterol-diet, and were given para-tyrosine or vehicle orally. High-cholesterol feeding lead to a significant increase in aortic wall meta-tyrosine content and a decreased vasorelaxation of the aorta to insulin and the glucagon-like peptide-1 analogue, liraglutide, that both could be prevented by administration of para-tyrosine. Concluding, these data suggest that meta- and ortho-tyrosine are potential markers of oxidative stress in acute diseases related to oxidative stress, and may also interfere with insulin action in septic humans. Competition of meta- and ortho-tyrosine by supplementation of para-tyrosine may exert a protective role in oxidative stress-related diseases.

Modeling long-term diabetes and related complications in rats.

INTRODUCTION: Accurate preclinical modeling of diabetic complications such as retinopathy, nephropathy and neuropathy is crucial to enable the development of novel preventative therapies. The aims of this study were to establish a model of long-term diabetes with sustained medium scale hyperglycemia and characterize the pathological changes detectable after 4months, with particular respect to dependence on the degree of hyperglycemia. METHODS: Streptozotocin-induced diabetic CFY rats were subjected to four different insulin substitution protocols to achieve different levels of glycemic control (Diabetic 1-4 groups). Eyes were investigated by ophthalmoscopy, kidney function by urine analysis, and neuropathy by functional tests. Retinal and renal morphological evaluations were performed by histology, immuno-histochemistry and electron microscopy. RESULTS: Rats of the Diabetic 3 group showed massive hyperglycemia-dependent anterior segment neovascularization, enhanced total retinal score and retinal apoptotic cell number, degeneration of dopaminergic amacrine cells, increased glomerular PAS-positivity, altered excreted total protein/creatinine ratio and cold allodynia, parallel with medium scale hyperglycemia (blood glucose level between 22 and 25mmol/L) and satisfying state of health. DISCUSSION: We established a treatment protocol in rats enabling complex investigation of diabetic retinopathy, nephropathy and neuropathy on a long-term period. Clearly hyperglycemic dependent parameters of these complications serve as good outcome measures for preclinical trials. Our results provide a useful basis for designing studies for testing preventative treatments as well as other translational medical research in this field.

Time courses of changes of para-, meta-, and ortho-tyrosine in septic patients: A pilot study.

OBJECTIVES: Sepsis is associated with oxidative stress. Due to oxidative stress, three tyrosine isoforms, para-, meta-, and ortho-tyrosine (p-, m-, and o-Tyr), can be formed non-enzymatically in smaller amounts. p-Tyr is mainly formed physiologically in the kidneys through the activity of the phenylalanine hydroxylase enzyme. The three tyrosine isoforms may undergo different renal handling. METHODS: Twenty septic patients were involved in the study and 25 healthy individuals served as controls. Blood and urine levels of p-, m-, and o-Tyr were measured on admission and four consecutive days. RESULTS: Serum m-Tyr levels were higher in septic patients than in controls on days 2 (P = 0.031) and 3 (P = 0.035). Serum p-Tyr levels were lower in the cases than in controls on days 1 (P = 0.005) and 2 (P = 0.040), and subsequently normalized due to a day-by-day elevation (P = 0.002). The tendency of urinary m-Tyr concentration was decreasing (P = 0.041), while that of urinary p-Tyr concentration was increasing (P = 0.001). Fractional excretion of m-Tyr (FEm-Tyr) showed a decreasing tendency (P = 0.009), and was, on all days, higher than FEp-Tyr, which remained near-normal, less than 4%. Procalcitonin showed significant correlation with FEm-Tyr (r = 0.454; P < 0.001). DISCUSSION: Our data suggest that the oxidative stress marker m-Tyr and physiologic p-Tyr may be handled differently in septic patients. The excretion of m-Tyr correlates with inflammation. m-Tyr may be actively secreted or produced in the kidney in some patients, whereas the decreased serum level of p-Tyr is a consequence of diminished renal production and not of renal loss.

Insulin Therapy of Nondiabetic Septic Patients Is Predicted by para-Tyrosine/Phenylalanine Ratio and by Hydroxyl Radical-Derived Products of Phenylalanine.

Hydroxyl radical converts Phe to para-, meta-, and ortho-Tyr (p-Tyr, m-Tyr, o-Tyr), while Phe is converted enzymatically to p-Tyr in the kidney and could serve as substrate for gluconeogenesis. Pathological isoforms m- and o-Tyr are supposed to be involved in development of hormone resistances. Role of Phe and the three Tyr isoforms in influencing insulin need was examined in 25 nondiabetic septic patients. Daily insulin dose (DID) and insulin-glucose product (IGP) were calculated. Serum and urinary levels of Phe and Tyr isoforms were determined using a rpHPLC-method. Urinary m-Tyr/p-Tyr ratio was higher in patients with DID and IGP over median compared to those below median (P = 0.005 and P = 0.01, resp.). Urinary m-Tyr and m-Tyr/p-Tyr ratio showed positive correlation with DID (P = 0.009 and P = 0.023, resp.) and with IGP (P = 0.004 and P = 0.008, resp.). Serum Phe was a negative predictor, while serum p-Tyr/Phe ratio was positive predictor of both DID and IGP. Urinary m-Tyr and urinary m-Tyr/p-Tyr, o-Tyr/p-Tyr, and (m-Tyr+o-Tyr)/p-Tyr ratios were positive predictors of both DID and IGP. Phe and Tyr isoforms have a predictive role in carbohydrate metabolism of nondiabetic septic patients. Phe may serve as substrate for renal gluconeogenesis via enzymatically produced p-Tyr, while hydroxyl radical derived Phe products may interfere with insulin action.

Para-Tyrosine Supplementation Improves Insulin- and Liraglutide- Induced Vasorelaxation in Cholesterol-Fed Rats.

Former data of our workgroup indicated that the accumulation of oxidized amino acids (meta- and ortho-tyrosine) due to oxidative stress may play an important role in the impaired insulininduced vasoactive properties of different arterial segments. There are evidences, that incorporation of these amino acids into cellular proteins leads to certain hormonal resistances, which might be restored by supplementation with the physiologic isoform, para-tyrosine. Rats in the control group were kept on a regular diet, rats in the cholesterol-fed group received high-fat diet, while the third group of rats received high-fat diet with para-tyrosine supplementation for 16 weeks. Plasma cholesterol level was significantly higher in the cholesterol-fed group, while the level of cholesterol in the cholesterol+para-tyrosine group did not differ significantly from that of the controls. Plasma level of insulin after glucose stimulation was decreased in the cholesterol-fed group, while that in the para-tyrosine supplemented group did not differ significantly from the controls. Vascular para-, meta- and ortho-tyrosine content was measured with HPLC. Elevated vascular meta-tyrosine/para-tyrosine ratio of cholesterol fed rats could be avoided by para-tyrosine supplementation. Vascular response of the thoracic aorta to insulin and liraglutide was assessed by a DMT multi-myograph. Cholesterol feeding resulted in vascular insulin-and liraglutide resistance, which was restored by para-tyrosine supplementation. Incorporation of the oxidative stress induced pathological tyrosine isoforms leads to vascular-hormone-resistances. We show that the physiological amino acid para-tyrosine is capable of restoring hypercholesterolemia-induced increased meta-tyrosine content of the vascular wall, thus attenuating functional vascular damage.

Tyrosine isomers and hormonal signaling: A possible role for the hydroxyl free radical in insulin resistance.

Oxidative stress processes play a major role in the development of the complications associated with diabetes and other diseases via non-enzymatic glycation, the hexosamine pathway, the polyol pathway and diacylglycerol-protein kinase C. Oxidative stress may lead to the production of hydroxyl free radicals, which can attack macromolecules, such as lipids, nucleic acids or amino acids. Phenylalanine (Phe) can be enzymatically converted to the physiological para-tyrosine (p-Tyr); however, a hydroxyl free radical attack on Phe may yield meta- and ortho-tyrosine (m- and o-Tyr, respectively) in addition to p-Tyr. Hence, m- and o-Tyr may be regarded as markers of hydroxyl free radical-induced damage. Their accumulation has been described; e.g., this accumulation has been found in the urine of patients with diabetes mellitus (DM) and/or chronic kidney disease, in cataract lenses, in vessel walls, in irradiated food and in amniotic fluid, and it may serve as an indicator of oxidative stress. The use of resveratrol to treat patients with type 2 DM led to a decrease in the urinary excretion of o-Tyr and concomitantly led to an improvement in insulin signaling and insulin sensitivity. Literature data also suggest that m- and o-Tyr may interfere with intracellular signaling. Our group has shown that erythropoietin (EPO) has insulin-like metabolic effects on fat cells in addition to its ability to promote the proliferation of erythroid precursor cells. We have shown that the supplementation of cell culture medium with m- and o-Tyr inhibits erythroblast cell proliferation, which could be ameliorated by p-Tyr. Additionally, in vivo, the o-Tyr/p-Tyr ratio is higher in patients with renal replacement therapy and a greater need for EPO. However, the o-Tyr/p-Tyr ratio was an independent determinant of EPO-resistance indices in our human study. The o-Tyr content of blood vessel walls inversely correlates with insulin- and acetylcholine-induced vasodilation, which could be further impaired by artificial oxidative stress and improved by the use of antioxidants. In rats that receive o-Tyr supplements, decreased vasorelaxation is detected in response to insulin. Additionally, o-Tyr supplementation led to the incorporation of the unnatural amino acid into cellular proteins and caused a decrease in the insulin-induced phosphorylation of endothelial nitric oxide synthase. Our data suggest that m- and o-Tyr may not only be markers of oxidative stress; instead, they may also be incorporated into cellular proteins, leading to resistance to insulin, EPO and acetylcholine.

Exenatide induces aortic vasodilation increasing hydrogen sulphide, carbon monoxide and nitric oxide production.

BACKGROUND: It has been reported that GLP-1 agonist exenatide (exendin-4) decreases blood pressure. The dose-dependent vasodilator effect of exendin-4 has previously been demonstrated, although the precise mechanism is not thoroughly described. Here we have aimed to provide in vitro evidence for the hypothesis that exenatide may decrease central (aortic) blood pressure involving three gasotransmitters, namely nitric oxide (NO) carbon monoxide (CO), and hydrogen sulphide (H2S). METHODS: We determined the vasoactive effect of exenatide on isolated thoracic aortic rings of adult rats. Two millimetre-long vessel segments were placed in a wire myograph and preincubated with inhibitors of the enzymes producing the three gasotransmitters, with inhibitors of reactive oxygen species formation, prostaglandin synthesis, inhibitors of protein kinases, potassium channels or with an inhibitor of the Na+/Ca2+-exchanger. RESULTS: Exenatide caused dose-dependent relaxation of rat thoracic aorta, which was evoked via the GLP-1 receptor and was mediated mainly by H2S but also by NO and CO. Prostaglandins and superoxide free radical also play a part in the relaxation. Inhibition of soluble guanylyl cyclase significantly diminished vasorelaxation. We found that ATP-sensitive-, voltage-gated- and calcium-activated large-conductance potassium channels are also involved in the vasodilation, but that seemingly the inhibition of the KCNQ-type voltage-gated potassium channels resulted in the most remarkable decrease in the rate of vasorelaxation. Inhibition of the Na+/Ca2+-exchanger abolished most of the vasodilation. CONCLUSIONS: Exenatide induces vasodilation in rat thoracic aorta with the contribution of all three gasotransmitters. We provide in vitro evidence for the potential ability of exenatide to lower central (aortic) blood pressure, which could have relevant clinical importance.

Association of plasma ortho-tyrosine/para-tyrosine ratio with responsiveness of erythropoiesis-stimulating agent in dialyzed patients.

Objectives Patients with end-stage renal failure (ESRF) treated with erythropoiesis-stimulating agents (ESAs) are often ESA-hyporesponsive associated with free radical production. Hydroxyl free radical converts phenylalanine into ortho-tyrosine, while physiological isomer para-tyrosine is formed enzymatically, mainly in the kidney. Production of 'para-tyrosine' is decreased in ESRF and it can be replaced by ortho-tyrosine in proteins. Our aim was to study the role of tyrosines in ESA-responsiveness. Methods Four groups of volunteers were involved in our cross-sectional study: healthy volunteers (CONTR; n = 16), patients on hemodialysis without ESA-treatment (non-ESA-HD; n = 8), hemodialyzed patients with ESA-treatment (ESA-HD; n = 40), and patients on continuous peritoneal dialysis (CAPD; n = 21). Plasma ortho-, para-tyrosine, and phenylalanine levels were detected using a high performance liquid chromatography (HPLC)-method. ESA-demand was expressed by ESA-dose, ESA-dose/body weight, and erythropoietin resistance index1 (ERI1, weekly ESA-dose/body weight/hemoglobin). Results We found significantly lower para-tyrosine levels in all groups of dialyzed patients when compared with control subjects, while in contrast ortho-tyrosine levels and ortho-tyrosine/para-tyrosine ratio were comparatively significantly higher in dialyzed patients. Among groups of dialyzed patients the ortho-tyrosine level and ortho-tyrosine/para-tyrosine ratio were significantly higher in ESA-HD than in the non-ESA-HD and CAPD groups. There was a correlation between weekly ESA-dose/body weight, ERI1, and ortho-tyrosine/para-tyrosine ratio (r = 0.441, P = 0.001; r = 0.434, P = 0.001, respectively). Our most important finding was that the ortho-tyrosine/para-tyrosine ratio proved to be an independent predictor of ERI1 (ß = 0.330, P = 0.016). In these multivariate regression models most of the known predictors of ESA-hyporesponsiveness were included. Discussion Our findings may suggest that elevation of the ratio of ortho-tyrosine/para-tyrosine could be responsible for decreased ESA-responsiveness in dialyzed patients.

Salivary proteomic analysis of diabetic patients for possible oral squamous cell carcinoma biomarkers.

Since oral squamous cell carcinoma (OSCC) is one of the most important causes of death worldwide, the prevention and early detection plays a crucial role. Recent epidemiological studies have incriminated diabetes as a risk factor for the development of OSCC, as well as oral premalignant lesions. As for the last 20 years diabetes and oral squamous cell carcinoma rates have been increasing rapidly, therefore a reliable detection method of major saliva proteins as possible biomarkers for OSCC is of key priority. In this study we collected whole saliva samples from patients with diabetes and from healthy subjects. To reduce the risk of failure and to keep the investigation good reproducible, we proposed an examination and saliva collecting technique. The proteins were analyzed using SDS-PAGE and MALDI TOF/TOF mass spectrometry. Our findings show that the expression of Annexin A8, Peroxiredoxin-2 and Tyrosine kinase is elevated by patients having diabetes. All these proteins have been previously described in cancer saliva samples also in OSCC. Our current findings showed that testing saliva may be an effective and reliable method for detecting oral cancer in early stages.

Incorporation of ortho- and meta-tyrosine into cellular proteins leads to erythropoietin-resistance in an erythroid cell line.

BACKGROUND/AIMS: Erythropoietin-resistance is an unsolved concern in the treatment of renal anaemia. We aimed to investigate the possible role of ortho- and meta-tyrosine - the hydroxyl free radical products of L-phenylalanine - in the development of erythropoietin-resistance. METHODS: TF-1 erythroblast cell line was used. Cell concentration was determined on day 1; 2 and 3 by two independent observers simultaneously in Bürker cell counting chambers. Protein concentration was determined with colorimetric method. Para-, ortho- and meta-tyrosine levels were measured using reverse phase-HPLC with fluorescence detection. Using Western blot method activating phosphorylation of STAT5 and ERK1/2 were investigated. RESULTS: We found a time- and concentration-dependent decrease of erythropoietin-induced proliferative activity in case of ortho- and meta-tyrosine treated TF-1 erythroblasts, compared to the para-tyrosine cultured cells. Decreased erythropoietin-response could be regained with a competitive dose of para-tyrosine. Proteins of erythroblasts treated by ortho- or meta-tyrosine had lower para-tyrosine and higher ortho- or meta-tyrosine content. Activating phosphorylation of ERK and STAT5 due to erythropoietin was practically prevented by ortho- or meta-tyrosine treatment. CONCLUSION: According to this study elevated ortho- and meta-tyrosine content of erythroblasts may lead to the dysfunction of intracellular signaling, resulting in erythropoietin-hyporesponsiveness.

Histological diagnosis determines complications of percutaneous renal biopsy: a single-center experience in 353 patients.

BACKGROUND: We studied the connection between complication occurrence related to renal biopsies and histological diagnoses of the biopsy specimen. We also analyzed the distribution of diagnoses in our population. METHODS: We retrospectively studied 353 patients undergoing renal biopsy at the same center. Biopsies were performed after marking the site of puncture by ultrasound imaging. Connection of complications with diagnoses and clinical parameters was evaluated. RESULTS: Complication rate was 44.5% in our study. There was a significantly lower rate of complications in patients with diabetic nephropathy (likelihood ratio, LR = 0.44) or acute tubular necrosis (LR = 0.38), while patients with thin basement membrane syndrome had a more than 6-fold higher risk for development of intrarenal hemorrhage than others. Patients with vasculitis (LR = 2.88) and acute interstitial nephritis (LR = 3.18) have a more than doubled risk for arteriovenous shunts, while in patients with severe arteriosclerosis the prevalence of this complication was lower (LR = 0.46). Arteriovenous shunts developed also at a significantly higher rate in patients with rapidly progressive glomerulonephritis. CONCLUSION: Patients with thin basement membrane syndrome, vasculitis, rapidly progressive glomerulonephritis or acute interstitial nephritis should be observed more carefully after renal biopsy due to the significantly higher risk for certain complications.

Accumulation of renin and imidazolone in peritubular capillary endothelial cells in insulin-resistant hypertensive rats.

BACKGROUND: Peritubular endothelium plays a key role in the development and progression of diabetic and nondiabetic chronic kidney disease. Renal injury in disorders of glucose metabolism may appear as early as in the stage of impaired glucose tolerance (IGT) and is accelerated by hypertension. The aim of our study was to investigate renal histology in rats with hypertension and IGT, with special emphasis on the peritubular endothelium. METHODS: Hypertension and IGT (H/IGT) were provoked in adult male Wistar rats by bilateral administration of methylglyoxal into the ventromedial hypothalamus. Immunohistochemistry with anti-renin and anti-imidazolone antibodies and immunoelectron microscopy with anti-renin antibody were performed. RESULTS: H/IGT rats showed tubulointerstitial fibrosis as well as renin and imidazolone staining in the papillary region. The patterns of immunostaining for renin and imidazolone were similar to that of endothelium. On electron microscopy, peritubular capillary endothelial cells and to a less extent, tubular epithelial cells showed renin positivity. DISCUSSION: Impaired glucose tolerance complicated with hypertension leads to tubulointerstitial fibrosis in rat kidney. Imidazolone deposition and renin production in peritubular capillary endothelial cells may play a role in the development of tubulointerstitial fibrosis.

Resveratrol improves insulin sensitivity, reduces oxidative stress and activates the Akt pathway in type 2 diabetic patients.

Although resveratrol has widely been studied for its potential health benefits, little is known about its metabolic effects in humans. Our aims were to determine whether the polyphenol resveratrol improves insulin sensitivity in type 2 diabetic patients and to gain some insight into the mechanism of its action. After an initial general examination (including blood chemistry), nineteen patients enrolled in the 4-week-long double-blind study were randomly assigned into two groups: a resveratrol group receiving oral 2 × 5 mg resveratrol and a control group receiving placebo. Before and after the second and fourth weeks of the trial, insulin resistance/sensitivity, creatinine-normalised ortho-tyrosine level in urine samples (as a measure of oxidative stress), incretin levels and phosphorylated protein kinase B (pAkt):protein kinase B (Akt) ratio in platelets were assessed and statistically analysed. After the fourth week, resveratrol significantly decreased insulin resistance (homeostasis model of assessment for insulin resistance) and urinary ortho-tyrosine excretion, while it increased the pAkt:Akt ratio in platelets. On the other hand, it had no effect on parameters that relate to ß-cell function (i.e. homeostasis model of assessment of ß-cell function). The present study shows for the first time that resveratrol improves insulin sensitivity in humans, which might be due to a resveratrol-induced decrease in oxidative stress that leads to a more efficient insulin signalling via the Akt pathway.

Effects of mono- and dual blockade of the renin-angiotensin system on markers of cardiovascular status in hypertensive patients with mild and moderate renal failure.

BACKGROUND/AIMS: Dual renin-angiotensin system (RAS) blockade has no more efficiency to decrease cardiovascular mortality than mono-blockade. Our goal was to explore differences between other cardiovascular markers in patients with RAS blockade. METHODS: We analyzed two groups of patients treated with a long-term ACE inhibitor (MONO-group, n = 20) and an ACE inhibitor and angiotensin II receptor blocker (DUAL-group, n = 15). Ambulatory blood pressure monitoring, echocardiography, arterial stiffness and levels of catecholamine, endogenous ouabain (EO), pro-brain natriuretic peptide and more types of urinary albumin measurements were performed. RESULTS: In the DUAL-group, we found significantly better cardiac parameters, but the levels of EO and urinary albumins were similar in both groups. The level of EO correlates with nighttime mean arterial blood pressure (R = 0.556, p = 0.032) and arterial ß-stiffness (R = 0.512, p = 0.042). Urinary immuno-unreactive albumin showed a relationship with diastolic dysfunction of the heart (R = -0.508, p = 0.045) diurnal index of diastolic blood pressure (R = -0.569, p = 0.021) in the MONO-group. CONCLUSION: Cardiac parameters were more prosperous in the DUAL-group, but the levels of EO did not differ between groups. The level of EO correlated with blood pressure and arterial stiffness markers in the MONO-group only. The urinary immuno-unreactive albumin may be a new marker of cardiovascular conditions.