Tissue transglutaminase is expressed, active, and directly involved in rat dermal wound healing and angiogenesis

Tissue transglutaminase (TG) is an enzyme that stabilizes the structure of tissues by covalently ligating extracellular matrix molecules. Expression and localization of TG are not well established during wound healing. We performed punch biopsy wounds on anesthetized rats and monitored the wound healing process by histological and immunohistochemical methods. The TG antigen and activity are expressed at sites of neovascularization in the provisional fibrin matrix within 24 h of wounding. Endothelial cells, macrophages, and skeletal muscle cells expressed TG throughout the healing process. The TG antigen within the wound was active in vivo based on the detection of isopeptide bonds. The TG antigen increased four- to fivefold by day 3 postwounding and was proteolytically degraded. TG expression occurred in association with TGF-beta, TNF-alpha, IL-6, and VEGF production in the wound. Recombinant TG increased vessel length density (a measure of angiogenesis) when applied topically in rat dorsal skin flap window chambers. We have established that TG is an important tissue stabilizing enzyme that is active during wound healing and can function to promote angiogenesis.

Asymmetric inter- and intramolecular cyclopropanation of alkenes catalyzed by chiral ruthenium porphyrins. Synthesis and crystal structure of a chiral metalloporphyrin carbene complex

Extensive investigations of asymmetric intermolecular cyclopropanation of terminal alkenes with diazoacetates catalyzed by ruthenium porphyrin [Ru(P*)(CO)(EtOH)] (1, H2P = 5,10,15,20-tetrakis[(1S,4R,5R,8S)-1,2,3,4,5,6,7,8-octahydro-1,4:5,8-dimethanoanthracene-9-yl]porphyrin) and the application of catalyst 1 to asymmetric intramolecular cyclopropanation of allylic or homoallylic diazoacetates are described. The intermolecular cyclopropanation of styrene and its derivatives with ethyl diazoacetate afforded the corresponding cyclopropyl esters in up to 98% ee with high trans/cis ratios of up to 36 and extremely high catalyst turnovers of up to 1.1 x 10(4). Examination of the effects of temperature, diazoacetate, solvent, and substituent in the intermolecular cyclopropanation reveals that (i) both enantioselectivity and trans selectivity increase with decreasing temperature, (ii) sterically encumbered diazoacetates N2CHCO2R, such as R = Bu(t), and donor solvents, such as diethyl ether and tetrahydrofuran, are beneficial to the trans selectivity, and (iii) electron-donating para substituents on styrene accelerate the cyclopropanations, with the log(k(X)/k(H)) vs sigma(+) plot for para-substituted styrenes p-X-C6H4CH=CH2 (X = MeO, Me, Cl, CF3) exhibiting good linearity with a small negative rho(+) value of -0.44 +/- 0.09. In the case of intramolecular cyclopropanation, complex 1 promoted the decomposition of a series of allylic diazoacetates to form the cyclopropyl lactones in up to 85% ee, contributing the first efficient metalloporphyrin catalyst for an asymmetric intramolecular cyclopropanation. Both the inter- and intramolecular cyclopropanations were proposed to proceed via a reactive chiral ruthenium carbene intermediate. The enantioselectivities in these processes were rationalized on the basis of the X-ray crystal structures of closely related stable chiral carbene complexes [Ru(P*)(CPh2)] (2) and [Ru(P*)(C(Ph)CO2CH2CH=CH2)] (3) obtained from reactions of complex 1 with N2CPh2 and N2C(Ph)CO2CH2CH=CH2, respectively.

A microtiter plate transglutaminase assay utilizing 5-(biotinamido)pentylamine as substrate

Transglutaminases belong to an important family of enzymes involved in hemostasis, skin formation, and wound healing. We describe a technique for the measurement of transglutaminase activity using polystyrene microtiter plates coated with N,N'-dimethylcasein. The substrate 5-(biotinamido)pentylamine is covalently incorporated into N,N'-dimethylcasein by transglutaminase in a calcium-dependent reaction. The biotinylated product is detected by streptavidin-alkaline phosphatase and quantitated by measuring the absorbance at 405 nm following the addition of p-nitrophenyl phosphate. The assay is sensitive, specific, and linear at plasma factor XIIIa concentrations between 0.08 and 1.25 micrograms/ml and at purified guinea pig liver transglutaminase concentrations between 0.05 and 0.8 microgram/ml. The intra-assay coefficient of variation is less than 8%. The solid-phase assay was used to quantitate the transglutaminase activity in Escherichia coli extracts expressing recombinant factor XIII A-chains and to analyze factor XIIIa inhibitors. This method will facilitate the analysis of structure-function relationships of the transglutaminases using recombinant DNA methods. Furthermore, screening of natural and synthetic factor XIIIa inhibitors will be expedited by this solid-phase microtiter plate assay.

Calcium regulates S-nitrosylation, denitrosylation, and activity of tissue transglutaminase

Nitric oxide (NO) and related molecules play important roles in vascular biology. NO modifies proteins through nitrosylation of free cysteine residues, and such modifications are important in mediating NO's biologic activity. Tissue transglutaminase (tTG) is a sulfhydryl rich protein that is expressed by endothelial cells and secreted into the extracellular matrix (ECM) where it is bound to fibronectin. Tissue TG exhibits a Ca(2+)-dependent transglutaminase activity (TGase) that cross-links proteins involved in wound healing, tissue remodeling, and ECM stabilization. Since tTG is in proximity to sites of NO production, has 18 free cysteine residues, and utilizes a cysteine for catalysis, we investigated the factors that regulated NO binding and tTG activity. We report that TGase activity is regulated by NO through a unique Ca(2+)-dependent mechanism. Tissue TG can be poly-S-nitrosylated by the NO carrier, S-nitrosocysteine (CysNO). In the absence of Ca(2+), up to eight cysteines were nitrosylated without modifying TGase activity. In the presence of Ca(2+), up to 15 cysteines were found to be nitrosylated and this modification resulted in an inhibition of TGase activity. The addition of Ca(2+) to nitrosylated tTG was able to trigger the release of NO groups (i.e. denitrosylation). tTG nitrosylated in the absence of Ca(2+) was 6-fold more susceptible to inhibition by Mg-GTP. When endothelial cells in culture were incubated with tTG and stimulated to produce NO, the exogenous tTG was S-nitrosylated. Furthermore, S-nitrosylated tTG inhibited platelet aggregation induced by ADP. In conclusion, we provide evidence that Ca(2+) regulates the S-nitrosylation and denitrosylation of tTG and thereby TGase activity. These data suggest a novel allosteric role for Ca(2+) in regulating the inhibition of tTG by NO and a novel function for tTG in dispensing NO bioactivity.

Regulation of human tissue transglutaminase function by magnesium-nucleotide complexes. Identification of distinct binding sites for Mg-GTP and Mg-ATP

Tissue transglutaminase (tTG) catalyzes a Ca(2+)-dependent transglutaminase (TGase) activity that stabilizes tissues and a GTP hydrolysis activity that regulates cell receptor signaling. The purpose of this study was to examine the true substrates for nucleotide hydrolysis and the effects of these substrates on modulating the dual enzymatic activities of tTG. We found that Mg-GTP and Mg-ATP are the true substrates of the hydrolysis reaction. tTG hydrolyzed Mg-GTP and Mg-ATP at similar rates and interacted with Mg-ATP (Km = 38 +/- 10 microM) at a 3-fold greater steady-state affinity than with Mg-GTP (Km = 130 +/- 35 microM). In addition, Mg-ATP inhibited GTP hydrolysis (IC50 = 24 microM), whereas 1 mM Mg-GTP reduced ATP hydrolysis by only 20%. Furthermore, the TGase activity of tTG was inhibited by Mg-GTP, Mg-GDP, and Mg-GMP, with IC50 values of 9, 9, and 400 microM, respectively, whereas the Mg-adenine nucleotides were ineffective. Kinetic analysis of the hydrolysis reaction demonstrates the presence of separate binding sites for Mg-GTP and Mg-ATP. Finally, we found that Mg-GTP protected tTG from proteolytic degradation by trypsin, whereas Mg-ATP was ineffective. In conclusion, we report that Mg-GTP and Mg-ATP can bind to distinct sites and serve as substrates for nucleotide hydrolysis. Furthermore, binding of Mg-GTP causes a conformational change and the inhibition of TGase activity, whereas Mg-ATP is ineffective. The implication of these findings in regulating the intracellular and extracellular function of tTG is discussed.

Seroepidemiological survey of hepatitis E in Hong Kong by recombinant-based enzyme immunoassays

The agent that causes the enterally transmitted form of non-A, non-B hepatitis has been cloned and called hepatitis E virus (HEV). We have carried out a seroepidemiological survey on the prevalence of hepatitis E in Hong Kong. In a retrospective study, serum from 394 patients with acute viral hepatitis and 355 healthy subjects was tested for antibodies to HEV (anti-HEV) with a recombinant-based enzyme immunoassay. 65 (16.5%) patients with hepatitis were positive for IgM anti-HEV and 23 (5.8%) were also positive for IgM anti-HEV. Of 18 patients diagnosed as having acute non-A, non-B, non-C hepatitis, 6 were IgM anti-HEV positive. 17 (6%) patients in whom acute hepatitis A was diagnosed were also infected with HEV. None of 70 patients with acute hepatitis B or C or exacerbation of chronic hepatitis B was IgM anti-HEV positive. 57 (16.1%) of the healthy subjects were positive for IgG anti-HEV. The prevalence of IgG anti-HEV was higher in subjects over 20 years old than in younger subjects (24% vs 4%, p < 0.0001). IgG anti-HEV was detected in 26% of subjects who were positive for IgG antibody to HAV and in 7% of those negative for that antibody (p < 0.0001). We demonstrated the validity of the recombinant-based enzyme immunoassays for the diagnosis of hepatitis E. Our results suggest that hepatitis E accounts for a third of non-A, non-B, non-C hepatitis in Hong Kong and that coinfection of hepatitis A and E can occur.

Meta-analysis of mortality in dialysis patients with an implantable cardioverter defibrillator

Patients receiving dialysis are at high risk for sudden cardiac death. Although clinical trials have shown that implantable cardioverter-defibrillators (ICDs) are effective in improving survival in a variety of populations, dialysis patients have been routinely excluded from these analyses. The purpose of this meta-analysis was to synthesize the available evidence regarding the effectiveness of ICD therapy in patients receiving dialysis. Medline, EMBASE, Web of Science, and Google Scholar were searched for pertinent studies published from 1999 to 2008. In addition, hand searches of the relevant annual scientific sessions and major scientific meetings in North America and Europe from 2000 to 2008 were performed. All clinical reports describing outcomes of ICD therapy in relation to renal function were eligible. Four investigators independently extracted the data in a standardized manner. Seven studies were identified, with a total of 2,516 patients and 89 patients receiving dialysis. Despite having ICDs, patients receiving dialysis had a 2.7-fold higher mortality compared with those not receiving dialysis. The results were similar in fixed- and random-effects models. Comparing patients receiving dialysis and those with chronic kidney disease but not receiving dialysis, there was no significant difference in mortality (risk ratio 1.62, 95% confidence interval 0.84 to 3.14). No evidence of publication bias was found. In conclusion, this meta-analysis suggests that even in those with ICDs, there is still a 2.7-fold increased mortality risk in patients who receive dialysis compared with those who do not. Beta blockers may be less cardioprotective in patients with ICDs who are on dialysis.

Risk of developing severe sepsis after acute kidney injury: a population-based cohort study

Introduction

Sepsis has been a factor of acute kidney injury (AKI); however, little is known about dialysis-requiring AKI and the risk of severe sepsis after survival to discharge.

Methods

We conducted a population-based cohort study based on the Taiwan National Health Insurance Research Database from 1999 to 2009. We identified patients with AKI requiring dialysis during hospitalization and survived for at least 90 days after discharge, and matched them with those without AKI according to age, sex, and concurrent diabetes. The primary outcome was severe sepsis, defined as sepsis with a diagnosis of acute organ dysfunction. Individuals who recovered enough to survive without acute dialysis were further analyzed.

Results

We identified 2983 individuals (mean age, 62 years; median follow-up, 3.96 years) with dialysis-requiring AKI and 11,932 matched controls. The incidence rate of severe sepsis was 6.84 and 2.32 per 100 person-years among individuals with dialysis-requiring AKI and without AKI in the index hospitalization, respectively. Dialysis-requiring AKI patients had a higher risk of developing de novo severe sepsis than the non-AKI group. In subgroup analysis, even individuals with recovery from dialysis-requiring AKI were at high risk of developing severe sepsis.

Conclusions

AKI is an independent risk factor for severe sepsis. Even patients who recovered from AKI had a high risk of long-term severe sepsis.

C-terminal deletion of human tissue transglutaminase enhances magnesium-dependent GTP/ATPase activity

Tissue transglutaminase (tTG) exhibits a magnesium-dependent GTP/ATPase activity that is involved in the regulation of the cell cycle and cell receptor signaling. The portion of the molecule involved in GTP/ATP hydrolysis is unknown. We expressed and purified a series of C-terminal truncation mutants of human tTG as glutathione S-transferase fusion proteins (DeltaS538, DeltaE447, DeltaP345, DeltaC290, DeltaV228, and DeltaF185) to determine the effect on GTP/ATPase activity. The truncation of the C terminus did not change significantly the apparent Km value for either GTP or ATP. In contrast, the Kcat value for GTP was increased by 4.6- and 3-fold for the DeltaS538 and DeltaE447 mutants, respectively. The DeltaP345 mutant had the highest hydrolysis activity with a 34-fold increase. The hydrolysis activity then declined to 8.1-, 8.7-, and 1. 9-fold for the DeltaC290, DeltaV228, and DeltaF185 mutants, respectively. The Kcat for ATP changed in parallel with the GTPase results. Thin layer chromatography analysis of the hydrolysis reaction products revealed that ATP was rapidly converted to ADP followed by a much slower conversion of ADP to AMP when incubated with wild type tTG or the DeltaP345 mutant. There was a substantial decrease in the calcium-dependent TGase activity when the last 149 amino acid residues were deleted from the C terminus. Less than 5% of the TGase activity was detected for the DeltaS538 and DeltaE447 mutants. In conclusion, we have located the ATP and GTP hydrolytic domain to amino acid residues 1-185. The C terminus functions to inhibit the expression of endogenous GTP/ATPase activity of tTG, and the potential role of the C terminus in modulating this activity is discussed.

Hepatitis C viral load, genotype, and increased risk of developing end-stage renal disease: REVEAL-HCV study

The association between hepatitis C virus (HCV) infection and end-stage renal disease (ESRD) remains controversial without considering the role of HCV viral load and genotype. This study aimed to determine whether HCV RNA level and genotype affect the risk of developing ESRD. Between 1991 and 1992, 19,984 participants aged 30-65 years were enrolled in a community-based prospective cohort study in Taiwan. Chronic HCV infection was defined by detectable HCV viral load. ESRD was determined as the need for chronic dialysis or renal transplantation. Conventional Cox proportional hazard and competing risk models were used to determine the hazard ratio (HR) for ESRD. After a median follow-up of 16.8 years, 204 cases were detected during 319,474 person-years. The incidence rates of ESRD for nonchronically HCV-infected and chronically HCV-infected patients were 60.2 and 194.3 per 100,000 person-years, respectively. The multivariable HR was 2.33 (95% confidence interval [CI] 1.40-3.89) when comparing patients with and without chronic HCV infection. Patients with low and high HCV RNA levels were at higher risk of ESRD than those who were nonchronically HCV-infected (HR, 2.11, 95% CI 1.16-3.86, and HR, 3.06, 95% CI 1.23-7.58; P_trend < 0.001). This association remained robust after taking pre-ESRD death as a competing event for ESRD. Patients with HCV genotype 1 tended to have a higher risk of developing ESRD (HR, 3.60 95% CI 1.83-7.07) compared with nonchronically HCV-infected subjects.

CONCLUSIONS

This study reveals that chronic HCV infection is associated with an increased risk of developing ESRD and suggests that elevated serum levels of HCV RNA (>167,000 IU/mL) and HCV genotype 1 are strong predictors of ESRD, indicating clinical implications for the management of chronic HCV. (Hepatology 2017;66:784-793).

Long-term remote organ consequences following acute kidney injury

Acute kidney injury (AKI) has been a global health epidemic problem with soaring incidence, increased long-term risks for multiple comorbidities and mortality, as well as elevated medical costs. Despite the improvement of patient outcomes following the advancements in preventive and therapeutic strategies, the mortality rates among critically ill patients with AKI remain as high as 40–60 %. The distant organ injury, a direct consequence of deleterious systemic effects, following AKI is an important explanation for this phenomenon. To date, most evidence of remote organ injury in AKI is obtained from animal models. Whereas the observations in humans are from a limited number of participants in a relatively short follow-up period, or just focusing on the cytokine levels rather than clinical solid outcomes. The remote organ injury is caused with four underlying mechanisms: (1) “classical” pattern of acute uremic state; (2) inflammatory nature of the injured kidneys; (3) modulating effect of AKI of the underlying disease process; and (4) healthcare dilemma. While cytokines/chemokines, leukocyte extravasation, oxidative stress, and certain channel dysregulation are the pathways involving in the remote organ damage. In the current review, we summarized the data from experimental studies to clinical outcome studies in the field of organ crosstalk following AKI. Further, the long-term consequences of distant organ-system, including liver, heart, brain, lung, gut, bone, immune system, and malignancy following AKI with temporary dialysis were reviewed and discussed.

Sphingosylphosphocholine reduces the calcium ion requirement for activating tissue transglutaminase

Tissue transglutaminase (tTG) catalyzes a Ca2+-dependent transglutaminase reaction resulting in the formation of gamma-glutamyl-epsilon-lysine bonds and is activated during apoptosis to catalyze the formation of apoptotic body. We investigate whether lipids that are membrane components and involved in cell signaling could modify the Ca2+-dependent activation of tTG. We found that sphingosylphosphocholine (lyso-SM) was the only lipid to activate transglutaminase at low Ca2+ concentrations. In the presence of lyso-SM (125 microM), transglutaminase was detectable at 10 microM Ca2+, whereas in the absence of lyso-SM, similar activity was obtained at 160 microM Ca2+. Furthermore, in the presence of lipid vesicles lyso-SM retained the ability to enhance the Ca2+-dependent activation of tTG. Lyso-SM did not significantly change the Km for the glutamyl and primary amine substrates. However, the Kact for Ca2+ was reduced from 300 microM to 90 microM. Structure-function studies of lyso-SM analogs indicate that phosphocholine group on C1, the free amino group at C2 and a C4-C5 double bond are critical for the activation of transglutaminase activity. This is the first demonstration that a specific sphingolipid could enhance the activity of tTG and could play a role in vivo in activation of the tTG at physiologic Ca2+ levels.

Earlier versus later initiation of renal replacement therapy among critically ill patients with acute kidney injury: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Although the optimal timing of initiation of renal replacement therapy (RRT) in critically ill patients with acute kidney injury has been extensively studied in the past, it is still unclear.

METHODS

In this systematic review, we searched all related randomized controlled trials (RCTs) that directly compared earlier and later RRT published prior to June 25, 2016, from PubMed, MEDLINE, and EMBASE. We extracted the study characteristics and outcomes of all-cause mortality, RRT dependence, and intensive care unit (ICU) and hospital length of stay (LOS).

RESULTS

We identified 51 published relevant studies from 13,468 screened abstracts. Nine RCTs with 1627 participants were included in this meta-analysis. Earlier RRT was not associated with benefits in terms of mortality [relative risk (RR) 0.88, 95% confidence interval (CI) 0.68-1.14, p = 0.33] and RRT dependence (RR 0.81, 95% CI 0.46-1.42, p = 0.46). There were also no significant differences in the ICU and hospital LOS between patients who underwent earlier versus later RRT [standard means difference -0.08 (95% CI -0.26 to 0.09) and -0.11 (95% CI -0.37 to 0.16) day, respectively]. In subgroup analysis, earlier RRT was associated with a reduction in the in-hospital mortality among surgical patients (RR 0.78, 95% CI 0.64-0.96) and patients who underwent continuous renal replacement therapy (CRRT) (RR 0.80, 95% CI 0.67-0.96).

CONCLUSIONS

Compared with later RRT, earlier initiation of RRT did not show beneficial impacts on patient outcomes. However, a lower rate of death was observed among surgical patients and in those who underwent CRRT. The included literature is highly heterogeneous and, therefore, potentially subject to bias. Further high-quality RCT studies are warranted.

Predictors and prevalence of latent tuberculosis infection in patients receiving long-term hemodialysis and peritoneal dialysis

Background

Tuberculosis is a common infectious disease in long-term dialysis patients. The prevalence of latent tuberculosis infection (LTBI) in this population is unclear, particularly in those receiving peritoneal dialysis (PD). This study investigated the prevalence of LTBI in patients receiving either hemodialysis (HD) or PD to determine predictors of LTBI and indeterminate results of interferon-gamma release assay.

Methods

Patients receiving long-term (≥3 months) HD or PD from March 2011 to February 2012 in two medical centers were prospectively enrolled. QuantiFERON-Gold in tube (QFT) test was used to determine the status of LTBI after excluding active tuberculosis. The LTBI prevalence was determined in patients receiving different dialysis modes to obtain predictors of LTBI and QFT-indeterminate results.

Results

Of 427 patients enrolled (124 PD and 303 HD), 91 (21.3%) were QFT-positive, 316 (74.0%) QFT-negative, and 20 (4.7%) QFT-indeterminate. The prevalence of LTBI was similar in the PD and HD groups. Independent predictors of LTBI were old age (OR: 1.034 [1.013–1.056] per year increment), TB history (OR: 6.467 [1.985–21.066]), and current smoker (OR: 2.675 [1.061–6.747]). Factors associated with indeterminate QFT results were HD (OR: 10.535 [1.336–83.093]), dialysis duration (OR: 1.113 [1.015–1.221] per year increment), anemia (OR: 8.760 [1.014–75.651]), and serum albumin level (OR: 0.244 [0.086–0.693] per 1 g/dL increment).

Conclusion

More than one-fifth of dialysis patients have LTBI. The LTBI prevalence is similar in PD and HD patients but is higher in the elderly, current smokers, and those with prior TB history. Such patients require closer follow-up. Repeated or alternative test may be required for malnutrition patients who received long length of HD.

High hepatitis C viral load and genotype 2 are strong predictors of chronic kidney disease

Associations between chronic hepatitis C virus (HCV) infection and chronic kidney disease (CKD) remain controversial. Here we aimed to clarify the association between HCV viral load, genotype, and CKD in 13,805 participants aged 30-65 years enrolled in the REVEAL-HCV Study, a community-based prospective study conducted in 1991-1992. CKD was defined by consecutive proteinuria or an estimated glomerular filtration rate (eGFR) under 60 mL/min/1.73 m². Chronic HCV infection was defined by detectable HCV viral load. Logistic regression models were used to estimate prevalence odds ratio of CKD for chronic HCV infection after adjusting for other risk factors. Compared to non-chronically HCV-infected participants, the adjusted prevalence odds ratio (95% confidence interval) for CKD was significantly increased to 1.91 (1.27-2.88) for chronically HCV-infected participants. Compared to non-chronically HCV-infected participants, the adjusted prevalence odds ratio of CKD was 1.21 (0.54-2.70), 1.40 (0.66-3.00) and 3.44 (1.92-6.14) for chronically HCV-infected participants with low to high tertiles of serum HCV RNA, respectively. The adjusted prevalence odds ratios of CKD were 0.54 (0.17-1.75) for participants with low HCV RNA and genotype 1, 1.80 (0.84-3.87) for those with low HCV RNA and genotype 2, 2.62 (1.11-6.17) for those with high HCV RNA and genotype 1 and 4.99 (2.25-11.06) for those with high HCV RNA and genotype 2, compared with non-chronically HCV-infected participants. Thus, chronic HCV infection is associated with an increased risk of CKD. High HCV viral load and HCV genotype 2 are strong CKD predictors.

Renoprotective effect of combining pentoxifylline with angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker in advanced chronic kidney disease

BACKGROUND/PURPOSE

Several studies have shown the renoprotective effects of pentoxifylline in the treatment of chronic kidney disease (CKD). This study was conducted to examine whether there was an increased benefit of including pentoxifylline with angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB) in the treatment of CKD.

METHODS

A single-center retrospective analysis was conducted. A total of 661 Stage 3B-5 CKD patients who received ACEI or ARB treatment were recruited. The patients were divided into the pentoxifylline use group and the no pentoxifylline group. Renal survival analysis of the two groups was compared. Subgroup analysis was performed by dividing the patients into lower [urine protein to creatinine ratio (UPCR)<1 g/g] and higher (UPCR ≥ 1 g/g) proteinuria subgroups.

RESULTS

There was no between-groups difference regarding mortality and cardiovascular events. Addition of pentoxifylline showed a better renal outcome (p = 0.03). The protective effect of add-on pentoxifylline was demonstrated in the higher proteinuria subgroup (p = 0.005). In the multivariate Cox regression model, pentoxifylline use also showed a better renal outcome [hazard ratio (HR): 0.705; 95% confidence interval (CI): 0.498-0.997; p = 0.048]. This effect was more prominent in the higher proteinuria subgroup (HR: 0.602; 95% CI: 0.413-0.877; p = 0.008).

CONCLUSION

In the advanced stages of CKD, patients treated with a combination of pentoxifylline and ACEI or ARB had a better renal outcome than those treated with ACEI or ARB alone. This effect was more prominent in the higher proteinuria subgroup. More large randomized control trials are needed to provide concrete evidence of the add-on effect of pentoxifylline.

Cloning and characterization of two major 3-methylcholanthrene inducible hamster liver cytochrome P450s

We have studied the immunochemical properties of two major 3-methylcholanthrene inducible hamster liver cytochrome P450 isozymes, P450 MC1 and P450 MC4. Immunoblots using specific antibodies against P450 MC1 and P450 MC4 demonstrated that these two P450s were present in very low levels in control hamster livers and were greatly induced by 3-methylcholanthrene treatment. P450 MC1 was immunochemically different from P450 MC4, rat P450c and P450d, and rabbit LM4. The immunorelated polypeptide to P450 MC1 was not present in the control or the 3-methylcholanthrene-treated rat liver microsomes, whereas it was present in two human liver microsomal preparations. On the other hand, P450 MC4 was immunochemically related to rat P450d and rabbit LM4. The immunorelated polypeptide to P450 MC4 was present in the human and 3-methylcholanthrene-treated rat liver microsomes. We also isolated full-length cDNA clones encoding P450 MC1 and P450 MC4 mRNAs from a 3-methylcholanthrene-induced hamster liver cDNA library. The full-length cDNA clones of P450 MC1 and P450 MC4 contained 1771 and 1868 base pairs, which encoded polypeptides of 494 and 513 amino acids, respectively. RNA blot analysis revealed that the mRNAs for P450 MC1 and P450 MC4 were 2100 and 2600 bases in length, respectively. 3-Methylcholanthrene pretreatment increased the P450 MC1 mRNA level by 16-fold and the P450 MC4 mRNA level by 11-fold in the hamster livers. A comparison of the deduced amino acid sequences with other cytochrome P450s revealed that P450 MC1 was most similar to the mouse P450(15) alpha with 75% sequence identity, whereas P450 MC4 shared 87% identity with the rat P450d or mouse P3(450). These results indicated that P450 MC1 was a unique member (CYP2A8) in the P450IIA subfamily, whereas P450 MC4 was the hamster P450IA2.

Nephrologist Follow-Up Care of Patients With Acute Kidney Disease Improves Outcomes: Taiwan Experience

OBJECTIVES

Acute kidney injury (AKI) and acute kidney disease (AKD) are a continuum on a disease spectrum and frequently progress to chronic kidney disease. Benefits of nephrologist subspecialty care during the AKD period after AKI are uncertain.

METHODS

Patients with AKI requiring dialysis who subsequently became dialysis independent and survived for at least 90 days, defined as the AKD period, were identified from the Taiwanese population's health insurance database. Cox proportional hazard models using death as the competing risk before and after propensity-score matching were applied to evaluate various endpoints.

RESULTS

Among a total of 20 260 patients with AKI requiring dialysis who became dialysis independent, only 7550 (37.3%) patients were followed up with by a nephrologist (F/U_nephrol group) during the AKD period. During a mean 4.04 ± 3.56 years of follow-up, the patients in the F/U_nephrol group were more often administered statin, antihypertensives, angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB), diuretics, antiplatelet agents, and antidiabetic agents. The patients in the F/U_nephrol group had a lower mortality rate (hazard ratio [HR] = 0.87, P < .001) and were less likely to have major adverse cardiovascular events (MACE) (subdistribution HR [sHR] = 0.85, P < .001), congestive heart failure (CHF) (sHR = 0.81, P < .001), and severe sepsis (sHR = 0.88, P = .008) according to the Cox proportional model after adjusting for mortality as a competing risk. During the AKD period, an increase in the frequency of nephrology visits was associated with improved outcomes.

CONCLUSIONS

In this population-based cohort, even after weaning off acute dialysis, only a minority of patients visited a nephrologist during the AKD period. We showed that nephrology follow-up is associated with a decrease in MACE, CHF exacerbations, and sepsis, as well as lower mortality; thus it may improve outcomes in patients with AKD.

Accelerated versus standard initiation of renal replacement therapy for critically ill patients with acute kidney injury: a systematic review and meta-analysis of RCT studies

BACKGROUND

Acute kidney injury (AKI) is a common yet possibly fatal complication among critically ill patients in intensive care units (ICU). Although renal replacement therapy (RRT) is an important supportive management for severe AKI patients, the optimal timing of RRT initiation for these patients is still unclear.

METHODS

In this systematic review, we searched all relevant randomized controlled trials (RCTs) that directly compared accelerated with standard initiation of RRT from PUBMED, MEDLINE, EMBASE, and Cnki.net published prior to July, 20, 2020. We extracted study characteristics and outcomes of being free of dialysis, dialysis dependence and mortality. We rated the certainty of evidence according to Cochrane methods and the GRADE approach.

RESULTS

We identified 56 published relevant studies from 1071 screened abstracts. Ten RCTs with 4753 critically ill AKI patients in intensive care unit (ICU) were included in this meta-analysis. In our study, accelerated and standard RRT group were not associated with all-cause mortality (log odds-ratio [OR]: - 0.04, 95% confidence intervals [CI] - 0.16 to 0.07, p = 0.46) and free of dialysis (log OR: - 0.03, 95% CI - 0.14 to 0.09, p = 0.65). In the subgroup analyses, accelerated RRT group was significantly associated with lower risk of all-cause mortality in the surgical ICU and for those who received continuous renal replacement therapy (CRRT). In addition, patients in these two subgroups had higher chances of being eventually dialysis-free. However, accelerated initiation of RRT augmented the risk of dialysis dependence in the subgroups of patients treated with non-CRRT modality and whose Sequential Organ Failure Assessment (SOFA) score were more than 11.

CONCLUSIONS

In this meta-analysis, critically ill patients with severe AKI would benefit from accelerated RRT initiation regarding all-cause mortality and being eventually free of dialysis only if they were surgical ICU patients or if they underwent CRRT treatment. However, the risk of dialysis dependence was increased in the accelerated RRT group when those patients used non-CRRT modality or had high SOFA scores. All the literatures reviewed in this study were highly heterogeneous and potentially subject to biases. Trial registration CRD42020201466, Sep 07, 2020. https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=201466 .

New-Onset Diabetes After Acute Kidney Injury Requiring Dialysis

OBJECTIVE

Acute kidney injury (AKI) is related to a high prevalence of insulin resistance. However, information is lacking on the sequelae of further metabolic change among AKI requiring dialysis in patients who could be weaned off dialysis (acute kidney disease [AKD]).

RESEARCH DESIGN AND METHODS

Using the National Health Insurance Research Database from 2000 to 2010, with the exclusion of those with diabetes at the start, we identified 3,307 subjects with AKD and 9,921 matched control subjects from 963,037 hospitalized patients for the comparison of the outcomes, including new-onset diabetes and all-cause mortality.

RESULTS

Within the median follow-up period of 5.99 years, AKD patients had a higher incidence of new-onset diabetes than the matched control patients (5.16% vs. 4.17% per person-year, P = 0.001). AKD patients were at higher risk of mortality than control patients (adjusted hazard ratio [aHR] 1.27 [95% CI 1.18-1.36], P < 0.001). With mortality as a competing risk, a Cox proportional hazards analysis showed that AKD patients had a higher risk of subsequent diabetes (subhazard ratio [sHR] 1.18 [95% CI 1.07-1.30], P < 0.001) compared with the matched control patients. Subgroup analysis showed that patients with baseline hypertension (aHR 1.15 [95% CI 1.04-1.28]), hyperlipidemia (aHR 1.23 [95% CI 1.02-1.48]), and gout (aHR 1.23 [95% CI 1.03-1.46]) had increased odds of developing new-onset diabetes during follow-up.

CONCLUSIONS

Patients who experienced AKI had a higher incidence of developing new-onset diabetes and mortality. This observation adds evidence regarding potential metabolic dysregulation after AKI.

Serum Urate and Risk of Chronic Kidney Disease: A Mendelian Randomization Study Using Taiwan Biobank

OBJECTIVE

To evaluate the association between serum urate and risk of incident chronic kidney disease (CKD) and to assess whether serum urate plays a causal role in CKD.

PATIENTS AND METHODS

We conducted a prospective cohort study and Mendelian randomization analysis that analyzed longitudinal data from the Taiwan Biobank between January 1, 2012, and December 31, 2021.

RESULTS

A total of 34,831 individuals met the inclusion criteria, of which 4697 (13.5%) had hyperuricemia. After a median (interquartile range) follow-up of 4.1 (3.1-4.9) years, 429 participants developed CKD. After adjustment for age, sex, and comorbid conditions, each mg/dL increase in serum urate was associated with a 15% higher risk of incident CKD (HR, 1.15; 95% CI, 1.08 to 1.24; P<.001). The genetic risk score and seven Mendelian randomization methods revealed no significant association between serum urate levels and the risk of incident CKD (HR, 1.03; 95% CI, 0.72 to 1.46; P=0.89; all P>.05 for 7 Mendelian randomization methods).

CONCLUSION

This prospective, population-based cohort study showed that elevated serum urate is a significant risk factor for incident CKD; however, Mendelian randomization analyses failed to provide evidence that serum urate had a causal effect on CKD in the East Asian population.

Purification and characterization of recombinant human coagulant factor XIII A-chains expressed in E. coli

The purpose of this study was to develop an Escherichia coli expression system to facilitate study of the structure and function of blood coagulation factor XIII (FXIII) A-chains. We engineered an NcoI site into the full-length FXIII A-chain cDNA and subcloned it into pKK233-2 expression vector. A low level of full-length FXIII A-chain and a 30-kDa FXIII A-chain-related antigen were expressed in the JM 105 strain of E. coli. Protein sequencing of the 30-kDa protein demonstrated that it was synthesized by internal translation starting at either Met474 or Met475. We mutated the internal ribosome-binding sequences from AGGA to TGGT (pKF13A2 construct) and found that it yielded a 30-fold increase in the production of full-length FXIII A-chains. JM105 harboring pKF13A2 produced 20 mg of soluble FXIII A-chains antigen from 1 liter culture in TB medium. The recombinant FXIII A-chain was readily purified to homogeneity through PEG fractionation, Q-Sepharose, and mono-P column chromatography with a 2100-fold increase in specific activity and a yield of 150 to 200 micrograms of FXIII A-chains per liter of culture. The purified FXIII A-chains behaved as a dimer on gel filtration analysis, were thrombin- and calcium-activated, cross-linked fibrin, and bound to fibrin to the same extent as purified plasma FXIII A-chains and recombinant FXIII A-chains purified from yeast. These results document that FXIII A-chains can be readily expressed and purified from E. coli culture and that they retained properties similar to those of purified human factor XIII A-chains.(ABSTRACT TRUNCATED AT 250 WORDS)

Risk of sepsis in patients with primary aldosteronism

BACKGROUND

The interaction between hyperaldosteronism and immune dysfunction has been reported and glucocorticoid co-secretion is frequently found in primary aldosteronism (PA). The aforementioned conditions raise the possibility of the infection risk; however, clinical episodes of sepsis have not been reported in PA.

METHODS

Using Taiwan's National Health Insurance Research Database between 1997 and 2009, we identified PA and aldosterone-producing adenoma (APA) matched with essential hypertension (EH) at a 1:1 ratio by propensity scores. The incidences of sepsis and mortality after the index date were evaluated, and the risk factors of outcomes were identified using adjusted Cox proportional hazards models and taking mortality as a competing risk.

RESULTS

We enrolled 2448 patients with PA (male, 46.08%; mean age, 48.4 years). There were 875 patients who could be ascertained as APA. Taking mortality as the competing risk, APA patients had a lower incidence of sepsis than their matched EH patients (hazard ratio (HR) 0.29; P < 0.001) after target treatments. Patients receiving adrenalectomy showed a benefit of decreasing the risk of sepsis (PA vs EH, HR 0.14, P = 0.001; APA vs EH, HR 0.16, P = 0.003), but mineralocorticoid receptor antagonist treatment may differ. Compared with matched control cohorts, patients with APA had a lower risk of all-cause mortality (PA, adjusted HR 0.84, P = 0.050; APA, adjusted HR 0.31, P < 0.001) after target treatments.

CONCLUSIONS

Our study demonstrated that patients with PA/APA who underwent adrenalectomy could attenuate the risk of sepsis compared with their matched EH patients. We further found that APA patients with target treatments could decrease all-cause mortality compared with EH patients.

Effects of Statin Use in Advanced Chronic Kidney Disease Patients

Although statin treatment is recommended for patients with chronic kidney disease (CKD) stages I⁻IV, its potential benefits have not been reported in advanced CKD patients. Non-diabetic patients with advanced CKD (pre-dialysis patients, estimated glomerular filtration rate <15 mL/min/1.73 m²) were enrolled from a National Health Insurance Research Database with a population of 23 million. Statin users and non-users were matched using propensity scoring and analyzed using Cox proportional hazards models, taking mortality as a competing risk with subsequent end-stage renal disease (ESRD) and statin doses as time-dependent variables. A total of 2551 statin users and 7653 matched statin non-users were identified from a total 14,452 patients with advanced CKD. Taking mortality as a competing risk, statin use did not increase the risk of new-onset diabetes mellitus (NODM) or decrease the risk of de novo major adverse cardiovascular events (MACE), but reduced all-cause mortality (hazard ratio (HR) = 0.59 [95% CI 0.42⁻0.84], p = 0.004) and sepsis-related mortality (HR = 0.53 [95% CI 0.32⁻0.87], p = 0.012). For advanced CKD patients, statin was neither associated with increased risks of developing NODM, nor with decreased risk of de novo MACE occurrence, but with a reduced risk of all-cause mortality, mainly septic deaths.