Clinical and economic implications of false-positive heparin-induced thrombocytopenia immunoassays: utility of the 4T score.

Heparin-induced thrombocytopenia (HIT) is a prothrombotic condition induced by platelet-activating IgG antibodies that recognize PF4/heparin complexes. Diagnosis of HIT relies on enzyme immunologic assays (EIAs) and functional assays [serotonin release assay (SRA)]. Our institution uses a latex immunoturbidimetric assay (LIA), which has shown a positive-predictive value (PPV) of 55.6%, and a negative-predictive value (NPV) of 99.7%. The low PPV of EIAs/LIAs, in combination with the clinical delay in obtaining results of a SRA, commonly leads to a false-positive diagnosis of HIT and inappropriate treatment. We performed a single-institution retrospective study at a large tertiary center to assess patient management decisions and economic costs following a false-positive HIT (LIA) test. This study found an 89.5% incidence of false-positive HIT (LIA) tests. 97.4% of patients underwent anticoagulation changes. 69.6% of patients were switched to argatroban. Of patients with a false-positive HIT immunoassay (LIA), 42 (40.7%) patients were on a prophylactic dose of anticoagulation at the time of HIT (LIA) positivity, of which 22 (52.4%) were switched to full anticoagulation with either argatroban or fondaparinux. Of the 22 patients switched to full anticoagulation, 15 (68%) had low-probability 4T scores. Seven (8.8%) of patients had bleeding events after HIT (LIA) positivity. All seven patients were switched to argatroban from a full-dose heparin anticoagulation. Five of the seven patients were considered major bleeds. Utilization of argatroban incurred substantial costs, estimated at approximately $73 000 for false-positive HIT cases. False-positive HIT (LIA) tests contribute to unwarranted anticoagulation changes, increased bleeding risks, and substantial healthcare costs. Incorporating the 4T score into diagnostic algorithms may help mitigate these risks by guiding appropriate clinical decisions. Future research should focus on refining diagnostic approaches and standardizing management strategies to improve patient outcomes and cost-effectiveness in HIT diagnosis and management.

Assessment of serum symmetric dimethylarginine and creatinine concentrations in cats with urethral obstruction.

OBJECTIVES: The aims of this study were to evaluate serum symmetric dimethylarginine (SDMA) and creatinine concentrations in cats with urethral obstruction pre- and post-decompression of the obstruction, and to determine if pre-decompression values were predictive of post-decompression renal function, as measured by SDMA and creatinine. METHODS: This was a prospective observational study. Twenty-five client-owned cats with urethral obstruction were hospitalized for decompression of the obstruction. Serum SDMA and creatinine were prospectively assessed at presentation, 24 h post-decompression and 5-20 days post-decompression. Urinalysis and culture were assessed at presentation and at the final follow-up. Exclusion criteria included positive urine culture, reobstruction or failure to obtain required samples. RESULTS: Mean SDMA concentration dropped by 41.8% from an initial pre-decompression concentration of 17.6 µg/dl to 10.3 µg/dl 24 h post-decompression (P <0.001). The mean creatinine value dropped by 38.4% from an initial pre-decompression concentration of 2.5 mg/dl to 1.5 mg/dl 24 h post-decompression (P <0.001). There was no association between SDMA concentration at initial presentation and SDMA concentration 5-20 days after urethral catheterization (Spearman's ρ = 0.205, P = 0.314). Creatinine concentration upon initial presentation was associated with the 5-20 day values after urethral catheterization (Spearman's ρ = 0.583, P <0.002). Twenty percent of cases were excluded due to bacterial growth on initial urine culture. SDMA and creatinine concentrations were significantly higher in these cases (median 59 µg/dl and 10.9 mg/dl, respectively) compared with those with negative cultures (median 14 µg/dl and 1.6 mg/dl [P <0.002 and P <0.001], respectively). CONCLUSIONS AND RELEVANCE: Both SDMA and creatinine decreased significantly after urethral catheterization, suggesting that renal function post-decompression cannot be predicted by the pre-decompression concentrations of these values.

Assessment of ADMA, IMA, and Vitamin A and E Levels in Patients with Acne Vulgaris.

BACKGROUND: Acne vulgaris is a common skin disease in adolescents known to be associated with oxidative stress. However, the number of studies in which oxidative stress and antioxidants are evaluated together is limited. AIMS: In this study, we aimed to investigate L-arginine/nitric oxide (NO) pathway metabolites, ischemia-modified albumin (IMA), and vitamin A and E levels in patients with acne and its association with disease severity. PATIENTS/METHODS: Ninety patients with acne and 30 healthy adults were included in the study. The serum levels ofL-arjinin, L-arginine metabolites, IMA, and vitamins A and E measured in the patient and control groups. RESULTS: Asymmetric dimethylarginine (ADMA), LNG -monomethyl-L-arginine (L-NMMA) and symmetric dimethylarginine (SDMA), and IMA levels were significantly higher in the patients with acne than in the control group (P Ë‚ .05). The L-arginine/ADMA ratio and citrulline and vitamin A levels were significantly lower in patients with acne than those of the controls (P Ë‚ .05). ADMA and IMA plasma levels were increased in parallel with the disease severity (P Ë‚ .05). L-arginine/ADMA ratio, L-arginine, citrulline, and vitamin A plasma levels decreased as the disease became severe (P Ë‚ .05). Although L-arginine and vitamin E levels were lower in the patient group compared to the control group, the difference was not statistically significant (P Ëƒ .05). CONCLUSION: These results suggest that IMA and L-arginine-NO pathway associated with ischemia and oxidative stress may play an important role in the pathogenesis and progression of acne vulgaris.

Assessment of serum symmetric dimethylarginine and creatinine concentrations in hyperthyroid cats before and after a fixed dose of orally administered radioiodine.

BACKGROUND: Serum symmetric dimethylarginine (SDMA) is a sensitive renal biomarker for detecting early chronic kidney disease (CKD) in nonhyperthyroid cats, but knowledge regarding its performance in hyperthyroid cats remains limited. OBJECTIVES: To determine the relationship between serum SDMA, creatinine and total thyroxine (TT4) concentrations in hyperthyroid cats before (T0) and 3 months after (T1) receiving a PO fixed dose of radioiodine. ANIMALS: Eighty client-owned hyperthyroid cats. METHODS: Prospective cohort study. Serum TT4, and SDMA, creatinine concentrations, and urine specific gravity were measured at T0 and T1. Nonparametric tests were used to determine the relationship among SDMA, and creatinine and TT4 concentrations. Agreement between SDMA and creatinine regarding CKD staging at both time points was assessed using Goodman and Kruskal's gamma statistic. RESULTS: Mean serum SDMA concentration increased after treatment of hyperthyroidism. However, 21 of 75 cats experienced a decrease in SDMA between T0 and T1, whereas creatinine decreased in only 2 cats. A moderate correlation between SDMA and creatinine was seen at T1 (r = 0.53; P < .001) but not at T0 (r = 0.13; P = .25). Where assessable at T1, poor agreement was observed between SDMA and creatinine and CKD stage (Goodman and Kruskal's gamma 0.20; P = .29). CONCLUSIONS AND CLINICAL IMPORTANCE: Discordant outcomes between SDMA and creatinine after radioiodine treatment in cats with hyperthyroidism suggest extrarenal factors may interfere with the reliability of SDMA to adequately reflect renal function. As a result, SDMA should not be interpreted in isolation in hyperthyroid cats treated with radioiodine.

Assessment of Endothelial Dysfunction with Methylated Arginines and L-arginine in Cadmium-Exposed People: a Pilot Study.

BACKGROUND: Workers can be exposed to cadmium (Cd) in various industries. On the other hand, another potential source for Cd exposure is the food chain and smoking. Environmental pollution to Cd plays an important role in the development of atherosclerosis. Asymmetric dimethyl arginine (ADMA) levels promote the development of endothelial dysfunction and atherosclerosis-related diseases such as hypertension, acute coronary syndrome, congestive heart failure, and peripheral vascular diseases. The aim of this study is to evaluate the cardiovascular risks of non-symptomatic cadmium-exposed workers and to promote the value of methylated arginines in screening of toxic exposures. METHODS: A total 176 participants were included in the study which has been separated as control group (n = 79) and Cd-exposed group (n = 94). Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used for toxicological analysis of Cd levels. Also, liquid Chromatography-Mass Spectrometry (LC-MS/MS) was used for levels of methylated arginines such as ADMA, symmetric dimethylarginine (SDMA), NG-monomethyl-L-arginine (L-NM-MA), homoarginine, and citrulline. RESULTS: Statistically significant differences were observed for control and Cd-exposed groups, respectively as follows: Cd levels (0.25 ± 0.13 µg/L and 1.33 ± 0.61 µg/L), ADMA (0.16 ± 0.04 µmol/L and 0.22 ± 0.11 µmol/L), SDMA (0.21 ± 0.06 µmol/L and 0.27 ± 0.07 µmol/L), L-NMMA(0.02 ± 0.01 µmol/L and 0.03 ± 0.01µmol/L), and arginine/ADMA levels (695.82 ± 620.63 and 478.30 ± 432.61). CONCLUSIONS: Our results suggest that workers chronically exposed to Cd showed imbalances in endothelial parameters.

Assessment of symmetric dimethylarginine as a biomarker of renal function in hyperthyroid cats treated with radioiodine.

BACKGROUND: Measurement of serum creatinine (sCr) and urea nitrogen fail to detect decreased renal function in many hyperthyroid cats because of low muscle mass and glomerular hyperfiltration of affected cats. Serum symmetric dimethylarginine (sSDMA) is an earlier and more sensitive renal biomarker than sCr. OBJECTIVE: Evaluate sSDMA as a biomarker of renal function in hyperthyroid cats before (T0) and 1 month after (T1) radioiodine (131 I) treatment. ANIMALS: Forty-seven client-owned hyperthyroid nonazotemic cats were evaluated at T0 and T1. METHODS: A prospective study in which sCr and sSDMA concentrations were determined in 47 hyperthyroid cats at T0 and at T1. Glomerular filtration rate (GFR) was estimated at T0 and T1 in 10 of these 47 cats using plasma exogenous creatinine clearance test. RESULTS: Serum SDMA was elevated (>14 µg/dL) in 6 of 47 cats at T0 and normalized after treatment in 4 of those cats. All cats remained nonazotemic after treatment. In 10 cats in which GFR was measured, correlation between GFR and sSDMA was low and not significant (τb = -0.35, P = .17 at T0 and τb = -.22, P = .41 at T1), whereas correlation between GFR and sCr was moderate and significant (τb = -0.52, P < .05 at T0 and τb = -.53, P = <.05 at T1). CONCLUSIONS AND CLINICAL IMPORTANCE: Careful interpretation of mildly increased sSDMA with normal sCr in hyperthyroid cats is warranted as sSDMA values might normalize after resolution of hyperthyroidism in some cats. In this population of hyperthyroid cats, sSDMA was poorly correlated with GFR.

Free Pentosidine Assessment Based on Fluorescence Measurements in Spent Dialysate.

The aim of this study was to primarily explore the relationship between free pentosidine and the fluorescence properties of spent dialysate, and also to develop a model to assess the levels of free pentosidine in spent dialysate based on the fluorescence measurements. First, 40 patients (20 females and 20 males) were examined during 40 dialysis sessions. High-pressure liquid chromatography (HPLC) was used to measure the free pentosidine concentrations from the spent dialysate. The full fluorescence spectra of the spent dialysates were recorded and single- and multi-wavelength (MW) models were developed. The average free pentosidine concentrations in the spent dialysate measured by HPLC at the start and end of the dialysis session were (mean ± SD) 4.25 ± 3.11 and 0.94 ± 0.69 µg/L respectively. The removal ratios (RRs) between RR_lab and RR_MW were statistically similar (p > 0.2). The concentration of free pentosidine and the RR can therefore be estimated from the spent dialysate when utilising fluorescence measurements.

Gas-phase structural characterization of neuropeptides Y Y1 receptor antagonists using mass spectrometry: Orbitrap vs triple quadrupole.

Collision induced dissociation of triple quadrupole mass spectrometer (CID-QqQ) and high-energy collision dissociation (HCD) of Orbitrap were compared for four neuropeptides Y Y1 (NPY Y1) receptor antagonists and showed similar qualitative fragmentation and structural information. Orbitrap high resolution and high mass accuracy HCD fragmentation spectra allowed unambiguous identification of product ions in the range 0.04-4.25 ppm. Orbitrap mass spectrometry showed abundant analyte-specific product ions also observed on CID-QqQ. These results show the suitability of these product ions for use in quantitative analysis by MRM mode. In addition, it was found that all compounds could be determined at levels >1 µg L-1 using the QqQ instrument and that the detection limits for this analyzer ranged from 0.02 to 0.6 µg L-1. Overall, the results obtained from experiments acquired in QqQ show a good agreement with those acquired from the Orbitrap instrument allowing the use of this relatively inexpensive technique (QqQ) for accurate quantification of these compounds in clinical and academic applications.

MRI assessment of coronary microvascular endothelial nitric oxide synthase function using myocardial T1 mapping.

PURPOSE: Endothelial nitric oxide synthase (eNOS) plays a central role in regulating vascular tone, blood flow, and microvascular permeability. Endothelial dysfunction, including eNOS dysfunction, is an early biomarker of vascular disease. This study aimed to show that myocardial T1 mapping during nitric oxide synthase (NOS) inhibition could assess coronary microvascular eNOS function. METHODS: Wild-type mice, eNOS-/- mice, and wild-type mice fed a high-fat diet underwent T1 mapping at baseline and for 20 min after injection of NG -nitro-L-arginine methyl ester (LNAME), a NOS inhibitor. First-pass perfusion MRI was performed in wild-type mice at baseline and 5 min after LNAME injection. RESULTS: T1 mapping detected an increase in myocardial T1 5 min after an injection of 4 mg/kg LNAME compared with baseline in control mice (T1 = 1515 ± 30 ms with LNAME versus T1 = 1402 ± 30 ms at baseline, P < 0.05). No change in myocardial T1 after LNAME injection was observed in eNOS-/- mice. The change in T1 after LNAME injection was less in high-fat-diet mice (ΔT1 = 31 ± 14 ms at 12 weeks of diet and ΔT1 = 16 ± 17 ms at 18 weeks of diet) compared with mice fed a standard diet (ΔT1 = 113 ± 15 ms), with P < 0.05. First-pass MRI measured similar perfusion at baseline and 5 min after LNAME injection. CONCLUSIONS: NOS inhibition causes an increase in myocardial T1 in healthy mice, and this effect is mediated through eNOS. T1 mapping during NOS inhibition detects coronary microvascular eNOS dysfunction in high-fat-diet mice. T1 mapping during NOS inhibition may be useful in preclinical studies aiming to investigate mechanisms underlying and therapies for coronary microvascular eNOS dysfunction. Magn Reson Med 79:2246-2253, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Renalase Assessment With Regard to Kidney Function, Lipid Disturbances, and Endothelial Dysfunction Parameters in Stable Renal Transplant Recipients.

BACKGROUND: Renal transplant dysfunction has been shown to be independent predictor for premature cardiovascular disease and mortality. Renalase, a flavoprotein secreted by several tissues, including the kidney, has been found to regulate sympathetic tone and blood pressure. The purpose of this secondary analysis was to explore relationships among parameters of endothelial dysfunction, lipids, glomerular filtration rate, and renalase in 2 groups: renal transplant patients with controlled hypertension and healthy volunteers. METHODS: In the parent study, 73 renal transplant recipients and 32 age- and gender-matched controls were enrolled. A fasting sample for endothelial, lipid, and renalase values, along with other clinical parameters, was obtained. RESULTS: We found statistically significant inverse correlation between renalase and estimated glomerular filtration rate ( r = -0.552, P < .001), positive correlation between renalase and creatinine ( r = 0.364, P = .003), total cholesterol ( r = 0.578, P < .001), low-density lipoprotein cholesterol ( r = 0.261, P = .046), and non-high-density lipoprotein cholesterol ( r = 0.327, P = .01). Renalase inversely correlated with hemoglobin ( r = -0.232, P = .032) and positively with white blood cells ( r = 0.233, P = .032). There was a significant difference in plasma renalase with regard to chronic kidney disease stages ( F = 13.346, P < .001) but did not correlate with C-reactive protein. Renalase did not correlate with any of parameters of endothelial dysfunction, C-reactive protein, neither with some demographic data (gender, age, time or type of transplantation, risk factors). There were no differences in renalase concentration with regard to antihypertensive therapy. CONCLUSION: Renalase strongly and inversely correlated with kidney function, positively with creatinine and lipid disturbances. Due to that it is very likely that renalase levels are determined mostly by renal function.

Asymmetric dimethylarginine in the assessment of febrile neutropenia in hematological patients.

Asymmetric dimethylarginine (ADMA) has been recognized as an independent prognostic factor for sepsis mortality in intensive care units. No data are available on kinetics or prognostic value of ADMA in hematological patients. We evaluated the ability of ADMA to act as a predictor for complicated course of febrile neutropenia, defined as bacteremia and/or septic shock in adult hematological patients receiving intensive chemotherapy. This prospective study included 87 adult hematological patients with febrile neutropenia after an intensive chemotherapy for acute myeloid leukemia (AML) or after an autologous stem cell transplantation (ASCT). Plasma ADMA and serum C-reactive protein (CRP) levels were measured from the onset of fever (d0) and for 2 days (d1-d2) thereafter. The levels of ADMA were stable or had only minimal changes during the study period. There was no difference between the levels at any time-point in patients having complicated course compared to those without it. On the other hand, CRP levels were significantly higher on d1 (p = 0.016) in patients with bacteremia and/or septic shock than in those without. ADMA was not able to differentiate hematological patients with a complicated course from those without complications. Elevated ADMA levels are probably associated with organ dysfunction, which is rare in this group of patients, of whom about 95% can be successfully managed at the hematology ward.

Assessment of collagen quality associated with non-enzymatic cross-links in human bone using Fourier-transform infrared imaging.

Aging and many disease conditions, most notably diabetes, are associated with the accumulation of non-enzymatic cross-links in the bone matrix. The non-enzymatic cross-links, also known as advanced glycation end products (AGEs), occur at the collagen tissue level, where they are associated with reduced plasticity and increased fracture risk. In this study, Fourier-transform infrared (FTIR) imaging was used to detect spectroscopic changes associated with the formation of non-enzymatic cross-links in human bone collagen. Here, the non-enzymatic cross-link profile was investigated in one cohort with an in vitro ribose treatment as well as another cohort with an in vivo bisphosphonate treatment. With FTIR imaging, the two-dimensional (2D) spatial distribution of collagen quality associated with non-enzymatic cross-links was measured through the area ratio of the 1678/1692cm-1 subbands within the amide I peak, termed the non-enzymatic crosslink-ratio (NE-xLR). The NE-xLR increased by 35% in the ribation treatment group in comparison to controls (p<0.005), with interstitial bone tissue being more susceptible to the formation of non-enzymatic cross-links. Ultra high-performance liquid chromatography, fluorescence microscopy, and fluorometric assay confirm a correlation between the non-enzymatic cross-link content and the NE-xLR ratio in the control and ribated groups. High resolution FTIR imaging of the 2D bone microstructure revealed enhanced accumulation of non-enzymatic cross-links in bone regions with higher tissue age (i.e., interstitial bone). This non-enzymatic cross-link ratio (NE-xLR) enables researchers to study not only the overall content of AGEs in the bone but also its spatial distribution, which varies with skeletal aging and diabetes mellitus and provides an additional measure of bone's propensity to fracture.

Assessment of serum asymmetric dimethylarginine levels and left ventricular diastolic function in patients with ankylosing spondylitis.

AIM: To assess left ventricular diastolic functions and serum dimethylarginine (ADMA) concentrations, as well as the effect of different treatment strategies on ADMA concentrations and diastolic function parameters, in patients with ankylosing spondylitis (AS). METHOD: Sixty AS patients and 40 control subjects without classical cardiovascular (CV) risk factors were included in the study. Baseline clinical and echocardiographic variables were obtained. C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and ADMA levels were measured. Spinal mobility, disease activity and functional status were assessed using Bath Ankylosing Spondylitis Metrology Index, Bath Ankylosing Spondylitis Disease Activity Index and Bath Ankylosing Spondylitis Functional Index. RESULTS: CRP, ESR and ADMA levels were significantly higher in the AS group as compared to the control group. Two (5%) control subjects and six (10%) AS patients met the criteria for left ventricular diastolic dysfunction (DD) on conventional Doppler echocardiography, but the difference was not statistically significant (P = 0.36). However, using tissue Doppler imaging, 12 (20%) patients in the AS group and three (8%) subjects in the control group were diagnosed with left ventricular DD (P = 0.08). The anti-tumor necrosis factor (TNF)-α group, conventional therapy group and control group were compared in terms of ADMA, CRP, ESR levels and echocardiographic parameters. ADMA levels were significantly lower in anti-TNF-α group as compared to the conventional therapy group (P < 0.001). In the control group, ADMA levels were significantly lower than both treatment groups (P < 0.001). CONCLUSION: Increased ADMA levels reveal impaired nitric oxide metabolism in a relatively young group of patients with AS, who have no classical CV risk factors. Anti-TNF-α may have beneficial effect on endothelial function in AS patients by reducing ADMA levels.

Assessment of asymmetrical dimethylarginine metabolism in patients with critical illness.

BACKGROUND: Critically ill patients experience metabolic disorders including hypercatabolic state and hyperglycaemia, and these are associated with poor outcome. Hyperglycaemia and asymmetrical dimethylarginine (ADMA) are reported to have significant influences on endothelial dysfunction. The aim of this study was to examine the relationship between plasma ADMA and related arginine metabolism in patients with critical illness. MATERIALS AND METHOSDS: Two venous blood samples (EDTA) (104 patients), on admission and follow-up sample in the last day in intensive care unit (ICU) (died or discharge sample median 7, interquartile range (IQR) 6-8, range 5-15). Plasma ADMA, arginine, homoarginine and SDMA were measured by high-performance liquid chromatography (HPLC). RESULT: ADMA (P < 0·01) and SDMA (P < 0·05) were elevated, and homoarginine was decreased (P < 0·05) in nonsurvivors and was directly associated with predicted mortality rate (P < 0·05 and P < 0·001), Sequential Organ Failure Assessment (SOFA) (P < 0·05, P < 0·001), ICU stay (P < 0·05, P < 0·001) and mortality (P < 0·01, P < 0·05). ADMA was directly associated with SDMA (P < 0·001), albumin (P < 0·05), ICU stay and mortality (P < 0·01). SDMA was directly associated with creatinine (P < 0·001) and Acute physiology and Chronic Health Evaluation II score (P < 0·001). In the follow-up measurements, there was a significant decrease in SOFA score (P < 0·01), homoarginine (P < 0·01), aminotransferase (P < 0·01), Laboratory Glucose (P < 0·01) and albumin (P < 0·01). In contrast, there was an increase in arginine (P < 0·01), ADMA (P < 0·01), ADMA:SDMA ratio (P < 0·01) and the norepinephrine administration (P < 0·01). CONCLUSION: In the present longitudinal study, ADMA metabolism was altered in patients with critical illness and was associated with disease severity and mortality.

[Heparin-induced thrombocytopenia type II (HIT II) : A medical-economic view]. / Die heparininduzierte Thrombozytopenie (HIT II) : Eine medizinökonomische Betrachtung.

BACKGROUND: In the context of inpatient and increasingly ambulatory thrombosis prophylaxis, heparins have been recognised as standard therapy for decades. In addition to the therapeutic benefit, therapy with heparins also entails the risk of undesirable side effects, such as bleeding and thrombocytopenia. Heparin-induced thrombocytopenia (HIT II) is deemed a serious side effect. AIM: In the following work, HIT II is subjected to a medico-economic consideration (treatment, pharmaceuticals, subsequent costs due to possible complications) and, with regard to a possible HIT II prophylaxis, aspects of increasingly respected patient safety are also considered. METHODS: In the context of a literature search the active ingredients argatroban and danaparoid, which are approved for HIT II treatment, were evaluated. RESULTS: HIT II - especially in combination with thromboembolic complications - represents a medical-economic burden for the hospital. Although this is only an orientation guide, it shows that HIT II syndrome is not adequately cost-covered by the G­DRG system. An early thrombosis prophylaxis with argatroban/danaparoid for HIT II risk patients should therefore be taken into account for medical-related as well as patient safety-relevant aspects. According to experience, the pharmaceutical supply for these medically needed products (anticoagulants) should be ensured for reasons of patient safety. CONCLUSION: The risk of an immunological response to heparin therapy is known. Within the context of increased patient safety, thrombosis prophylaxis should be issued with a risk-adjusted prophylaxis.

Fitness costs restrict niche expansion by generalist niche-constructing pathogens.

We investigated the molecular and ecological mechanisms involved in niche expansion, or generalism, versus specialization in sympatric plant pathogens. Nopaline-type and octopine-type Agrobacterium tumefaciens engineer distinct niches in their plant hosts that provide different nutrients: nopaline or octopine, respectively. Previous studies revealed that nopaline-type pathogens may expand their niche to also assimilate octopine in the presence of nopaline, but consequences of this phenomenon on pathogen dynamics in planta were not known. Here, we provided molecular insight into how the transport protein NocT can bind octopine as well as nopaline, contributing to niche expansion. We further showed that despite the ability for niche expansion, nopaline-type pathogens had no competitive advantage over octopine-type pathogens in co-infected plants. We also demonstrated that a single nucleotide polymorphism in the nocR gene was sufficient to allow octopine assimilation by nopaline-type strains even in absence of nopaline. The evolved nocR bacteria had higher fitness than their ancestor in octopine-rich transgenic plants but lower fitness in tumors induced by octopine-type pathogens. Overall, this work elucidates the specialization of A. tumefaciens to particular opine niches and explains why generalists do not always spread despite the advantage associated with broader nutritional niches.

Umbilical cord asymmetric dimethylarginine levels and ultrasound assessment of carotid arteries in neonates born small for gestational age.

BACKGROUND: To examine asymmetric dimethylarginine (ADMA) level as an endothelial function parameter in addition to ultrasonographic evaluation of carotid arteries in babies born small for gestational age (SGA). METHODS: Twenty-six neonates born SGA and 34 appropriate for gestational age (AGA) controls were included in the study. The serum levels of ADMA were measured. Intima-media thickness (cIMT) and resistive index (cRI) of the both carotid arteries were determined by ultrasonography. RESULTS: The mean ADMA level was higher in SGA neonates compared to AGAs (16 267.7 ± 6050 versus 12 810.2 ± 3302 ng/L; p = 0.01). The mean cIMT (0.34 ± 0.02 versus 0.31 ± 0.03 mm; p = 0.001) and cRI (0.66 ± 0.07 versus 0.61 ± 0.04, p = 0.003) were also higher in SGAs. Serum ADMA levels were positively correlated to the mean cIMT (r = 0.41, p = 0.001). Although there was a weak correlation between cIMT and mean cRI (r = 0.26, p = 0.04), no correlation was found between ADMA and mean cRI (r = 0.17, p = 0.18). CONCLUSIONS: Neonates born SGA have elevated cord blood ADMA level in addition to thicker IMT and higher RI of carotid arteries at birth. ADMA was correlated to cIMT, suggesting that higher ADMA levels might influence vascular health in later life in these neonates.

Eficacia y seguridad del uso de l-arginina en pacientes con defecto del ciclo de la urea / Efficacy and safety of the use of l-arginine in patients with a defect in the urea cycle

INTRODUCCIÓN: La presente evaluación de tecnología sanitaria muestra la evidencia científica encontrada acerca del uso L-arginina (ARG) en pacientes con defectos del ciclo de la urea (DCU). Los DCU son desórdenes metabólicos caracterizados por la deficiencia de una de las seis enzimas que componen el ciclo de la urea: N-acetilglutamato sintentaza (NAGS), Carbomoil fosfato sintestasa (CPS), Ornitina transcarbamilasa (OTC), Ácido argininosuccínico sintetaza (ASS), Ácido argininosuccínico liasa (ASL), y Arginasa (ARGI). Los DCU que afectan el inicio del ciclo de la urea (NAGS, CPS, OTC) están generalmente asociados con elevaciones marcadas de amonio, mientras que los DCU más distales (ASS, ASL, ARGI) son menos propensos a desarrollar episodios de hiperamonemia. TECNOLOGÍA SANITARIA DE INTERÉS: La L-arginina (ARG) es un aminoácido considerado semi-esencial o condicionalmente esencial en los humanos. Además, es uno de los aminoácidos más versátiles metabólicamente, y es utilizado como precursor para la síntesis de urea, óxido nítrico, poliaminos, prolina, glutamato, creatina, y agmantina (Morris 2006) . Las fuentes principales de ARG son las proteínas dietarías, el recambio proteico, y la síntesis endógena de ARG. METODOLOGÍA: Se realizó una búsqueda de literatura científica en relación a la eficacia y seguridad del uso de la L-arginina (ARG) en pacientes pediátricos con defectos del ciclo de la urea (DCU). Se dio preferencia a guías de práctica clínica, revisiones sistemáticas con o sin meta-análisis y ensayos clínicos aleatorizados. Asimismo, se consideró extraer información con una estrategia de "bola de nieve" mediante la revisión de las referencias bibliográficas de las guías de práctica clínica, revisiones sistemáticas, estudios primarios, estudios descriptivos y revisiones narrativas encontradas, relevantes a la pregunta PICO a evaluar. La búsqueda de la literatura se realizó en las bases de datos The National Library of Medicine (Pubmed), The Web of Science, y Cochrane Library. Asimismo, se buscó información en los metabuscadores Epistemonikos, y Translating Research into Practice (TRIPDATABASE). RESULTADOS: Específicamente, la búsqueda de guías de prácticas clínicas se realizó en las páginas de internet de la National Institute for Health and Care Excellence (NICE); y The National Guideline of Clearinghouse (NGC), el repositorio creado por la Agencia para la Investigación en Salud y Calidad (AHRQ). Finalmente, se hizo una búsqueda en la página de registro de ensayos clínicos www.clinicaltrials.gov, para identificar estudios primarios en elaboración o que no hayan sido publicados aún. Se realizó la búsqueda bibliográfica y de evidencia científica que sustente el uso de la L-arginina (ARG) en pacientes pediátricos con defecto del ciclo de la urea (DCU). La evidencia encontrada que evalúa el uso de ARG en pacientes con DCU es escasa. Se ha identificado evidencia proveniente de dos guías de práctica clínica (GPC) y un estudio observacional. Las GPC incluidas recomiendan el uso de ARG intravenosa, en una concentración que varía de 250-400 mg/kg/día, dentro del protocolo de tratamiento de pacientes con DCU con niveles de amonio plasmático por encima de 100 µmol/L. En el caso del estudio observacional descrito, en los pacientes que recibieron suplementos de ARG vía oral, los resultados muestran una reducción significativa de los niveles de amonio en sangre, y una disminución considerable de la frecuencia de episodios de hiperamonemia. Así como un aumento en los niveles de L-arginina plasmática, y la talla. Sin embargo, se debe tener en cuenta que este estudio observacional tiene baja validez en relación a si los efectos observados de deben al uso de ARG. Ante la escasez de evidencia científica sólida proveniente de ensayos clínicos aleatorizados y controlados que sustenten la eficacia y seguridad del uso de ARG en pacientes con DCU, se recurre a la opinión de especialistas en pediatría. Así, los expertos, en línea con lo observado en la escasa evidencia presentada en el presente dictamen, reportan que aquellos pacientes pediátricos que no reciban tratamiento van a presentar secuelas neurológicas irreversibles ocasionadas por la intoxicación de amonio, además, deficiencia de L-arginina, la cual deriva en una inadecuada síntesis de proteínas, por ende, un inadecuado metabolismo muscular, regeneración celular, mala cicatrización, caída de cabello, entre otros. Asimismo, los especialistas mencionan que, si la hiperamonemia no es tratada a tiempo, esta puede derivar en coma y muerte. CONCLUSIÓN: El Instituto de Evaluación de Tecnologías en Salud e Investigación ­ IETSI, aprueba el uso de L-arginina en pacientes con desórdenes del ciclo de la urea, según lo establecido en el Anexo N° 01. La vigencia del presente dictamen preliminar es de dos años a partir de la fecha de publicación. Asimismo, se estable que el efecto del uso de ARG se evaluará con los datos de los pacientes que hayan recibido en el tratamiento en EsSalud, por el tiempo autorizado para determinar su impacto. Con esta información se realizará una reevaluación del medicamento, incluyendo una evaluación económica al terminar la vigencia del este dictamen.

Assessment of ADMA, estradiol, and progesterone in severe preeclampsia.

BACKGROUND: Decreased nitrous oxide (NO) levels are crucial factors in severe preeclampsia (sPE), and asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of NO synthetase. Steroid hormones are closely related to the vascular endothelium. This study determined the levels of and correlations between ADMA, estradiol (E2), and progesterone (Pg) in sPE to investigate the roles of these factors in this disease. METHODS: Sixty-two sPE patients (sPE group) were divided into the sPE1 subgroup (28(+1)-32(+0) weeks of pregnancy), the sPE2 subgroup (32(+1)-36(+0) weeks), and the sPE3 subgroup (36(+1)-40(+0) weeks) and 75 normal pregnant women (NC group) were divided into the NC1 subgroup (28(+1)-32(+0) weeks of gestation), the NC2 subgroup (32(+1)-36(+0) weeks), and the NC3 subgroup (36(+1)-40(+0) weeks). Serum and placental ADMA levels were measured by enzyme-linked immunosorbent assay (ELISA), and serum E2 and Pg concentrations were determined by the chemilumineseent immunoassay (CLIA). RESULTS: ADMA concentrations in both the placenta and the maternal serum were significantly higher in the sPE group (p < 0.05). Higher ADMA contents were observed in the placenta relative to the maternal serum (p < 0.05). Serum E2 levels were significantly lower in the sPE group (p < 0.05). For Pg, the only significant difference was observed between the sPE1 and NC1 subgroups (p < 0.05). The Pg/E2 ratios in the sPE groups were significantly higher, with a significant high positive correlation between Pg/E2 ratios and serum ADMA levels. CONCLUSION: Increased serum levels of ADMA in sPE may result from increased secretion from the placenta, and the increased Pg/E2 ratio may play a role in the development of sPE by aggravating ADMA.