Assessment of feed and economic efficiency of dairy farms based on multivariate aggregation of partial indicators measured on field.

Many of the metrics used to evaluate farm performance are only partial indicators of farm operations, which are assumed to be best predictors of the whole farm efficiency. The main objective of this work was to identify aggregated multiple indexes of profitability using common partial indicators that are routinely available from individual farms to better support the short-term decision-making processes of the cattle-feeding process. Data were collected from face-to-face interviews with farmers from 90 dairy farms in Italy and used to calculate 16 partial indicators that covered almost all indicators currently used to target feeding and economic efficiency in dairy farms. These partial indicators described feed efficiency, energy utilization, feed costs, milk-to-feed price ratio, income over feed costs, income equal feed cost, money-corrected milk, and bargaining power for feed costs. Calculations of feeding costs were based on lactating cows or the whole herd, and income from milk deliveries was determined with or without considering the milk quality payment. Multivariate factor analysis was then applied to the 16 partial indicators to determine simplified and latent structures. The results indicated that 5 factors explained 70% of the variability. Each of the original partial indicator was associated with all factors in different proportions, as indicated by loading scores from the multivariate factor analysis. Based on the loading scores, we labeled these 5 factors as "economic efficiency," "energy utilization," "break-even point," "milk-to-feed price," and "bargaining power of the farm," in decreasing order of explained communality. The first 3 factors shared 83% of the total communality. Feed efficiency was similarly associated with factor 1 (53% loading) and factor 2 (66% loading). Only factor 4 was significantly affected by farm location. Milk production and herd size had significant effects on factor 1 and factor 2. Our multivariate approach eliminated the problem of multicollinearity of partial indicators, providing simple and effective descriptions of farm feeding economics. The proposed method allowed the evaluation, benchmarking, and ranking of dairy herd performance at the level of single farms and at territorial level with high opportunity to be used or replicated in other areas.

Natural Killer Response and Lipo-Metabolic Profile in Adults with Low HDL-Cholesterol and Mild Hypercholesterolemia: Beneficial Effects of Artichoke Leaf Extract Supplementation.

The aim of the present study is to evaluate the effects of 60-day artichoke leaf extract (ALE) supplementation (250mg, twice daily) on cytokines levels, natural killer cell (NK) response, and lipo-metabolic profile (HDL, LDL, and total-cholesterol, triglycerides (TG), ApoB, ApoA, lipid accumulation product (LAP), glucose, insulin, and homeostasis model assessment of insulin resistance (HOMA-IR)) in twenty adults (9/11 males/females, age=49.10 ± 13.74 years, and BMI=33.12 ± 5.14 kg/m2) with low HDL-C and mild hypercholesterolemia. Hierarchical generalized linear model, adjusted for sex, BMI, and age, has been used to evaluate pre-post treatment changes. A significant increase for HDL-C (ß=0.14, p=0.0008) and MCP-1 (ß=144.77, p=0.004) and a significant decrease for ApoB/ApoA (ß=-0.07, p=0.03), total-C/HDL-C ratio (ß=-0.58, p<0.001), and NK response at stimulus low (ß=0.43, p=0.04), medium (ß=0.40, p<0.001), and high (ß=0.42, p=0.001) have been found. These results support the benefits of ALE supplementation on metabolic profile.

ATOPIC DERMATITIS: IS THERE A ROLE FOR PROBIOTICS?

Atopic dermatitis (AD) is a chronic inflammatory skin disease that commonly presents during early childhood. In the last decades the prevalence of AD has increased, especially in western societies. This frequently relapsing inflammatory condition has a strong impact on the quality of life of patients and families. The recent advances in the understanding of this disease have paved the way for the development of new strategies for the prevention and treatment of AD. Among the new therapeutic options, there is increasing interest in the potential benefit of probiotic supplementation. It has been widely demonstrated that the human microbiota plays a fundamental role not only in the maintenance of intestinal homeostasis through the interaction between microorganisms and the innate immune system, but also in the microbiota-mediated development of adaptive immunity. In addition, several studies have demonstrated that probiotics are able to influence the composition of gut microbiota and may exert immunomodulatory effects. According to these promising results, the possible application of probiotics in the therapeutic management of allergic diseases has been investigated in many studies. In particular, a considerable body of literature has been published analyzing the effects of probiotics on patients with AD. In order to shed light on frequently conflicting results, we reviewed the data regarding the application of probiotics in AD, with the aim to provide a state-of-the-art assessment of the most important studies exploring the role of probiotics both in the prevention and treatment of AD.

PROBIOTICS AND INFLAMMATORY BOWEL DISEASES.

Intestinal microbiota is composed by symbiotic innocuous bacteria and potential pathogens also called pathobionts. Even if the mechanism of action of intestinal bacteria remain still unknown, specific microbial species seem to have important role in the maintenance of immunological equilibrium in the gut through the direct interaction with immune cells. Some studies have found a dysregulated interaction between the intestinal bacteria, the gut barrier, and the intestinal associated immune system in Inflammatory Bowel Disease (IBD) patients and in the pathogenesis of these pathologies. In IBD patients some Butyrate producing bacteria, as Faecalibacterium Prausnitzii, are under represented and this could be related with their chronic inflammatory state.

Evaluation of the effects of a probiotic supplementation with respect to placebo on intestinal microflora and secretory IgA production, during antibiotic therapy, in children affected by recurrent airway infections and skin symptoms.

Antibiotic therapy, especially in pediatric patients, is often associated with significant modifications of the gut microflora, which can lead to intestinal dysbiosis and influence intestinal physiology and immune system functionality. Herein we report the results from a double blind controlled clinical trial in 77 pediatric patients affected by recurrent airway infections, receiving antibiotic therapy with amoxicillin and clavulanic acid. A group was treated with an oral probiotic preparation composed of Lactobacillus paracasei ssp.paracasei CRL-431, Bifidobacterium BB-12, Streptococcus thermophilus TH-4 and a fructooligosaccharide (FOS) during and after antibiotic therapy for seven days, while the other group received placebo. The study revealed a reduction in the Clostridia population, with a contemporary increase in Bifidobacteria and Lactobacilli in fecal samples in the probiotic group and an increase in the Enterobacteria population in the placebo group. Moreover, there was a decreasing trend in secretory IgA production in the probiotic group. Some relevant, but not statistically significant probiotic supplementation effects were identified.

FRETS-VWF73 rather than CBA assay reflects ADAMTS13 proteolytic activity in acquired thrombotic thrombocytopenic purpura patients.

Collagen-binding activity (CBA) and FRETS-VWF73 assays are widely adopted methods for the measurement of the plasmatic activity of ADAMTS13, the von Willebrand factor (VWF) cleaving-protease. Accurately assessing the severe deficiency of ADAMTS13 is important in the management of thrombotic thrombocytopenic purpura (TTP). However, non-concordant results between the two assays have been reported in a small but relevant percentage of TTP cases. We investigated whether CBA or FRETS-VWF73 assay reflects ADAMTS13 proteolytic activity in acquired TTP patients with non-concordant measurements. Twenty plasma samples with non-concordant ADAMTS13 activity results, <10% using FRETS-VWF73 and ≥20% using CBA, and 11 samples with concordant results, <10% using either FRETS-VWF73 and CBA assays, were analysed. FRETS-VWF73 was performed in the presence of 1.5 M urea. ADAMTS13 activities were also measured under flow conditions and the VWF multimer pattern was defined in order to verify the presence of ultra-large VWF due to ADAMTS13 deficiency. In FRETS-VWF73 assay with 1.5 M urea, ADAMTS13 activity significantly increased in roughly 50% of the samples with non-concordant results, whereas it remained undetectable in all samples with concordant measurements. Under flow conditions, all tested samples showed reduced ADAMTS13 activity. Finally, samples with non-concordant results showed a ratio of high molecular weight VWF multimers higher than normal. Our results support the use of FRETS-VWF73 over CBA assay for the assessment of ADAMTS13 severe deficiency and indicate urea as one cause of the observed differences.

Measurement and prevalence of circulating ADAMTS13-specific immune complexes in autoimmune thrombotic thrombocytopenic purpura.

BACKGROUND: The formation of ADAMTS13-specific circulating immune complexes (CICs) may be a pathophysiologic mechanism in autoimmune thrombotic thrombocytopenic purpura (TTP), but has not been systematically investigated. OBJECTIVES: (a) To develop an assay for ADAMTS13-specific CICs; (b) to evaluate their prevalence in autoimmune TTP; and (c) to assess their association with ADAMTS13-related measurements and clinical features in autoimmune TTP patients. PATIENTS/METHODS: We developed and validated an ELISA method for ADAMTS13-specific CICs. ADAMTS13-specific CICs were searched for in 55 patients with autoimmune TTP from the Milan TTP Registry (URL:http://www.ttpdatabase.org/) and 28 controls. The associations between ADAMTS13-specific CIC levels and ADAMTS13 activity, antigen, anti-ADAMTS13 IgGs and acute TTP clinical features were assessed by multivariate linear regression. RESULTS: Intra- and inter-assay coefficients of variation of the new test were 5.3 and 9.6%. In 36 patients with severe ADAMTS13 deficiency and anti-ADAMTS13 autoantibodies, the prevalence of ADAMTS13-specific CICs was 47% (n = 17; 95% confidence interval [CI], 32-63%). ADAMTS13-specific CICs were detected also in seven of 19 (37%; 95% CI, 19-59%) patients with reduced ADAMTS13 activity, but apparently negative anti-ADAMTS13 autoantibodies. ADAMTS13-specific CICs were not associated with ADAMTS13 activity, antigen or anti-ADAMTS13 IgGs. In patients with acute TTP, increasing levels of ADAMTS13-specific CICs were associated with a higher number of plasma-exchange procedures required to attain remission (per 0.1 increase in normalized OD values, beta, 2.9; 95% CI, -0.7 to 6.5). CONCLUSIONS: Approximately one to two-thirds of patients with autoimmune TTP display ADAMTS13-specific CICs. A thorough investigation of the prognostic relevance of ADAMTS13-specific CIC levels in autoimmune TTP is warranted.

Next-generation sequencing study finds an excess of rare, coding single-nucleotide variants of ADAMTS13 in patients with deep vein thrombosis.

BACKGROUND: The considerable genetic predisposition to deep vein thrombosis (DVT) is only partially accounted for by known genetic risk variants. Rare single-nucleotide variants (SNVs) of the coding areas of hemostatic genes may explain part of this missing heritability. The ADAMTS13 and VWF genes encode two interconnected proteins with fundamental hemostatic functions, the disruption of which may result in thrombosis. OBJECTIVES: To study the distribution and burden of rare coding SNVs of ADAMTS13 and VWF found by sequencing in cases and controls of DVT. PATIENTS/METHODS: The protein-coding areas of 186 hemostatic/proinflammatory genes were sequenced by next-generation technology in 94 thrombophilia-negative patients with DVT and 98 controls. Gene-specific information on ADAMTS13 and VWF was used to study the association between DVT and rare coding SNVs of the two genes. RESULTS: More than 70 billion base pairs of raw sequence data were produced to sequence the 700-kb target area with a median redundancy of × 45 in 192 individuals. Most of the 4366 SNVs identified were rare and non-synonymous, indicating pathogenetic potential. Rare (frequency of < 1%) and low-frequency (< 5%) coding SNVs of ADAMTS13 were associated with DVT (prevalence 17% vs. 4%; odds ratio [OR] 4.8 and 95% confidence interval [CI] 1.6-15.0 for rare coding; prevalence 36% vs. 23%, OR 1.9 and 95% CI 1.0-3.5 for low-frequency coding). Patients with rare coding SNVs of ADAMTS13 had lower plasma levels of ADAMTS-13 activity than patients without them. SNVs of VWF were not associated with DVT. CONCLUSIONS: We found an excess of rare coding SNVs of the ADAMTS13 gene in patients with DVT.

Outcome of oral provocation test in egg-sensitive children receiving semi-fat hard cheese Grana Padano PDO (protected designation of origin) containing, or not, lysozyme.

PURPOSE: Lysozyme, obtained from egg white, is a potential food allergen used in the dairy industry to prevent late blowing of the loaf caused by the outgrowth of clostridial spores (Cl. butyricum and Cl. tyrobutyricum) during cheese aging. The aim of this study was to evaluate the possible correlation between egg protein allergy in pediatric age and sensitization to egg lysozyme, used for the preparation of Grana Padano cheese. METHODS: The tolerability of Grana Padano cheese has been evaluated in pediatric patients allergic to egg proteins through an oral provocation test with increasing amounts of cheese containing, or not, lysozyme at 12 and 24 months of aging. RESULTS: When lysozyme-sensitized children received 12-months aged and lysozyme-containing cheese, several immediate and late adverse reactions such as itching, abdominal pain, vomiting, nausea, dermatitis, rhinitis, bronchial asthma, urticaria, and angioedema were seen in 5 out of 21 subjects; only 1 out of 21 children showed an adverse reaction after challenge with 24-months-ripened lysozyme-containing cheese. CONCLUSIONS: There is a possible relationship between the severity of allergic reactions and the lysozyme-specific IgE level in blood. In particular vomiting, hypotension, and abdominal pain were present when IgE level was higher than 7 kU/L. A ripening time of 24 months may reduce allergy problems when lysozyme-containing cheese is given to sensitized subjects, probably due to the hydrolysis of antigenic epitopes during aging.

ADAMTS-13 activity and autoantibodies classes and subclasses as prognostic predictors in acquired thrombotic thrombocytopenic purpura.

BACKGROUND: Thrombotic thrombocytopenic purpura (TTP) is a rare life-threatening disease. Of surviving patients, 45% develops an exacerbation or a late recurrence. Severe ADAMTS-13 deficiency, both during the acute episode and remission, is a well-established predictor of recurrence. The predictive value of anti-ADAMTS-13 antibodies, their inhibitory activity and Ig class subtype for disease recurrence is still to be established. OBJECTIVES: To analyze ADAMTS-13-related biomarkers (ADAMTS-13 and anti-ADAMTS-13 immunoglobulins, classes and subclasses) and their potential relationship with prognosis. PATIENTS/METHODS: In 115 patients with TTP, we assessed the association between levels of these biomarkers and the severity of acute episodes; we analysed also the hazard ratio (HR) and 95% confidence interval (CI) of recurrence in association with biomarkers levels retrieved at the previous acute episode or during remission, using Cox regression models. RESULTS: During the acute phase, higher IgA, IgG1 and IgG3 titers showed the strongest association with acute episode severity. In the survival analyzes, the only biomarker significantly associated with a high hazard of recurrence after an acute episode was the presence of IgG. Conversly, low ADAMTS-13 activity or antigen levels (<10%), the presence of ADAMTS-13 inhibitor or IgG during remission were all significantly associated with a higher hazard of recurrence. CONCLUSIONS: Both the Ig class and subclass are of predictive value for acute episode severity in patients with TTP. Although markers that could predict the risk of recurrence in the acute phase are limited, a thorough assessment of ADAMTS-13-related parameters during remission is warranted.

B lymphocyte subsets and their functional activity in the early months of life.

In the present study we evaluated B-cell subsets and their functional development in 74 newborns from birth to 6 months of life. Moreover, we evaluated natural antibody production in vitro. The results documented a predominance of naive B-lymphocytes at all time-points evaluated, decreasing from birth to 6 months (p=0.009). The percentages of CD27+IgD+ and CD27+IgDneg memory B-cells were very low at birth and significantly increased only at 6 months (p=0.02 and p less than 0.001, respectively). We found a significant increase only in in vitro stimulated IgG production at 6 months as compared to birth (p less than 0.001). Moreover, a lower secretion of anti-Pn IgM antibodies up to 6 months of age, as compared to controls was observed. Our results underline that the susceptibility and severe course of infection in the neonate can be attributed, at least in part, to the lack of pre-existing immunological memory and competent adaptive immunity.

[Probiotics and children: is an integration useful in allergic diseases?]. / Probiotici e bambini: è utile un'integrazione nei casi di allergia?

Recent studies report that some probiotic strains are able to improve allergic diseases. For this reason, we would verify tolerability and efficacy of a industrial preparation of Lactobacillus paracasei (11,688; Proge Farm, Italy) and Lactobacillus salivarius (11,794; Proge Farm, Italy) and value their "in vitro" immunomodulatory effect. We know that, after birth, there's a persistence of Th2 immune response that predisposes to atopy, whereas commensal bacteria are able to induce a Th1 immune response that counter-balances the original response. The "in vivo" study was set up with the recruitment of 20 atopic pediatric patients treated 30 days with 2 doses of Fiorilac (Sharper, Italy), a preparation of the two strains in the proportion of 1:12. Only one patient referred significant improvements of atopic disease, 19 patients reported a good tolerability to the product and 3 patients had a regularization of intestinal function. Immunological tests showed an increase of Th1 immune response as in CD4+ lymphocytes percentage as of IL-12 and IL-10 cytokines production and a significant increase of natural killer (NK) activity, which predisposes to an active response to viral infections and neoplastic transformations.

In vitro activation of mononuclear cells by two probiotics: Lactobacillus paracasei I 1688, Lactobacillus salivarius I 1794, and their mixture (PSMIX).

BACKGROUND: Most studies on probiotics have described their effects on the human immune system after ingestion of LAB, but little is known about their effect on in vitro stimulation of human immune cells. AIM OF THE STUDY: Evaluate the "in vitro" activity of Lactobacillus paracasei (I 1688), Lactobacillus salivarius (I 1794), and a commercial mix of the two (PSMIX, Proge Farm), on immune cells from healthy individuals. MATERIALS: Two probiotic strains, Lactobacillus salivarius (I 1794; Proge Farm, Italy) and Lactobacillus paracasei (I 1688; Proge Farm, Italy), which are contained in the functional food ENTEROBACILLI, were evaluated for their ability to stimulate peripheral blood mononuclear cells and modulate surface phenotype and cytokine production. RESULTS: All subjects responded to the bacteria, with different levels of response. The cell populations that showed a significant percent increase were CD4+/CD25+ cells (T-helper activated regulatory cells), CD8+/CD25+ (T-suppressor/cytotoxic activated cells), and CD16+/CD56+ (NK cells) (p<0.05). IL-12 and IFN-gamma in vitro production significantly increased with exposure to probiotics (p<0.05 for both). CONCLUSIONS: This study provides the first evidence that Lactobacillus paracasei and Lactobacillus salivarius are capable of inducing a specific immune response that may be useful in the clinical setting for improving innate and adaptive immune responses.

Reduced free protein S levels in patients with inflammatory bowel disease: prevalence, clinical relevance, and role of anti-protein S antibodies.

We evaluated free plasma levels of protein S, a natural anticoagulant factor, the prevalence of anti-protein S antibodies, a possible cause of protein S deficiency, and their correlation with anti-phospholipid antibodies in 53 patients with inflammatory bowel disease (IBD) and 53 age- and sex-matched controls. Mean free plasma protein S levels (+/- SD) were significantly lower in IBD patients (0.98+/-0.32 IU/ml) than in controls (1.06+/-0.28 IU/ml) (P < 0.05); only one patient showed protein S deficiency. Specific antibodies to protein S were found in four IBD patients (7.5%) and in one control (1.9%) (P = NS). Five IBD patients (9.4%) and none of the controls showed anti-phospholipid antibodies (P < 0.06). No correlation was found between free protein S levels and anti-protein S antibodies or between anti-protein S and anti-phospholipid antibodies. In conclusion, free plasma protein S levels are slightly but significantly decreased in IBD patients. The prevalence of anti-protein S and antiphospholipid antibodies is increased in IBD patients. Anti-protein S antibodies do not appear to determine low protein S levels or to overlap with or belong to anti-phospholipid antibodies.

Liver iron influences the response to interferon alpha therapy in chronic hepatitis C.

OBJECTIVE: To define whether there is any relation between the iron status of patients with hepatitis C virus (HCV) chronic liver disease and their response to interferon therapy. DESIGN: To evaluate the long-term response to 1 year of interferon therapy with addition of phlebotomies after 3 months of treatment if at that time alanine aminotransferase (ALT) had not normalized in a group of patients with HCV-positive chronic liver disease whose iron status had been characterized. SETTING: A northern Italian hospital. PARTICIPANTS: Fifty-eight anti-HCV-positive patients (four HCV-RNA negative) with biopsy proven chronic hepatitis and no evidence of iron overload as indicated by normal transferrin saturation at the time of enrollment in the study. INTERVENTION: Three times a week intramuscular injection of alpha interferon 3 MU for 1 year with addition of phlebotomies (350 ml/week) till iron depletion if after 3 months of interferon therapy ALT had not normalized. RESULTS: A long-term response was observed in 19 of the 52 patients who completed the treatment, four HCV-RNA negative and 15 positive. The four RNA-negative and seven of the 15 RNA-positive long-term responders had been treated with interferon alone, and the other eight also with phlebotomies. At univariate analysis only HCV genotype, gamma-glutamyltranspeptidase and liver iron concentration were significantly associated with response whereas sinusoidal iron deposition was of borderline significance. No association was found with sex, age, duration of disease, histology, Knodell score, transferrin saturation %, serum ferritin, hepatocytic iron score, and portal iron score. HCV-RNA serum levels, measured in 29 patients, did not correlate with response. At multivariate analysis liver iron concentration was still significant and one unit reduction of liver iron concentration (natural logarithm transformed) was associated with 2.95 odds ratio of response. CONCLUSION: These results indicate that iron in the liver is more closely related to response to interferon than the other variables considered, including HCV characteristics.

Free protein S deficiency is a risk factor for venous thrombosis.

A recent study suggests that protein S deficiency is not a risk factor for venous thrombosis. Since this unexpected finding would have important clinical implications if confirmed, we performed a case-control study with the aim to determine the prevalence of protein S deficiency in patients with thrombosis and in healthy individuals taken from the general population and the relative risk of thrombosis in protein S-deficient patients. Free protein S concentration was measured in 327 consecutive patients with at least one venous thrombotic episode and in 317 age- and sex-matched control individuals. Different normal reference ranges were obtained and adopted for men and women. Protein S deficiency was found in 3.1% (95% CI: 1.5-5.2) of patients and in 1.3% of controls (95% CI: 0.3-2.8). Ten patients and 4 control subjects had protein S deficiency, which determined a relative risk of thrombosis (sex- and age-adjusted odds ratio) of 2.4 (95% CI: 0.8-7.9). When men and women were analyzed separately, the risk was 5.0 (95% CI: 0.6-43.6) and 1.6 (95% CI: 0.4-6.7) respectively. PS-deficient men had more thrombotic episodes than women and later in life. Multivariate analysis established that sex was an independent determinant of the number of episodes, as was age, while PS deficiency was not. However sex and PS deficiency status were both determinants of age at first thrombotic episode.

JAGGED2: a putative Notch ligand expressed in the apical ectodermal ridge and in sites of epithelial-mesenchymal interactions.

The Drosophila Notch gene and its ligands, Delta and Serrate, are involved in cell fate determination in a variety of developing tissues. Recently, several Notch, Delta and Serrate homologues have been identified in vertebrates. We report here the cloning of the human and murine JAGGED2 (JAG2), a Serrate-like gene, and the analysis of its expression pattern during embryogenesis. Jag2 was found to be expressed as early as E9 in the surface ectoderm of the branchial arches and in the apical ectodermal ridge (AER) of the developing limb. At E12.5, Jag2 expression is upregulated in differentiated neurons of the central and peripheral nervous system and in the inner neuroblastic layer of the developing retina. Outside the nervous system, Jag2 is expressed in the developing vibrissae follicles, tooth buds, thymus, submandibular gland and stomach. Our findings suggest the involvement of Jagged2 in the development of the mammalian limb, branchial arches, central and peripheral nervous systems and several tissues whose development depends upon epithelial-mesenchymal interactions.

Sarcoidosis following beta-interferon therapy for multiple myeloma.

Some reports correlate the administration of all forms of interferon with the development or exacerbation of autoimmune phenomena and diseases, including sarcoidosis, because of the strong and complex immune action of interferons. We report on a case of sarcoidosis following beta-interferon treatment for multiple myeloma. Differently from what had been observed in all the 8 previously reported cases of associated multiple myeloma and sarcoidosis, where the plasmacellular malignancy followed the onset of the respiratory disease, in the case of our patient, sarcoidosis arose after multiple myeloma was first diagnosed.

Low levels of the anticoagulant activity of protein C in patients with chronic renal insufficiency: an inhibitor of protein C is present in uremic plasma.

Twenty-nine of 54 uremic patients had low levels of protein C measured as anticoagulant activity, contrasting with normal levels measured as amidolytic activity or antigenic concentration. We demonstrate that this discrepancy is due to the presence of a soluble plasma inhibitor that interferes specifically with the anticoagulant activity of activated protein C. The inhibitor does not interfere with other coagulation assays. It is resistant to diisopropylfluorophosphate, high temperatures and repeated freezing and thawing. It can be dissociated from protein C by anti-protein C antibodies or by dialysis in vitro and in vivo. It binds to positively charged resins and can be eluted with high salt concentrations without losing its inhibitory capacity. The inhibitory effect is correlated with plasma creatinine levels and fluctuates with time.