Anti-Trichomonas vaginalis activity of betulinic acid derivatives

Caused by Trichomonas vaginalis, trichomoniasis is the most common non-viral STD worldwide. Currently, metronidazole and tinidazole are the only drugs approved for treatment of the condition. However, problems such as metronidazole-resistant T. vaginalis isolates and allergic reactions have been reported. Based on data previously published by our group, structural changes in betulinic acid (1) were performed, generating three new compounds that were tested for in vitro anti-T.vaginalis activity in this study. Whereas derivative 2 did not demonstrate anti-T. vaginalis activity, derivatives 3 and 4 reduced trophozoite viability by 100%, with MIC values of 50 μM. The structural difference of two compounds was performed only on the C-28 position. Derivative 3 showed low cytotoxicity against Vero cells in 24 h; however, derivative 4 was highly cytotoxic, but efficient when associated with metronidazole in the synergism assay. ROS production by neutrophils was reduced, and derivative 3 showed anti-inflammatory effect. Collectively, the results of this study provide in vitro evidence that betulinic acid derivatives 3 and 4 are potential compounds with anti-T. vaginalis activity.     

Dalbavancin is active in vitro against biofilms formed by dalbavancin-susceptible enterococci

We tested the in vitro activity of dalbavancin, vancomycin and daptomycin against 83 enterococcal isolates in planktonic and biofilm states. The MIC₉₀ for vancomycin-susceptible Enterococcus faecalis was 0.125 and 4 μg/mL for dalbavancin and daptomycin, respectively. For vancomycin-resistant Enterococcus faecium, the MIC₉₀ was >16 and 2 μg/mL for dalbavancin and daptomycin, respectively. Dalbavancin minimum biofilm inhibitory concentrations (MBICs) for vancomycin-susceptible and -resistant isolates were ≤0.25 and >16 μg/mL, respectively. The daptomycin MBIC₉₀ for all isolates was 4 μg/mL. For E. faecalis and E. faecium, dalbavancin minimum biofilm bactericidal concentrations (MBBCs) for vancomycin-susceptible and -resistant isolates were ≤4 and >16 μg/mL, respectively, whereas vancomycin MBBCs were >128 μg/mL for all isolates, and daptomycin MBBC₉₀ values for both species were 128 μg/mL. In summary, dalbavancin exhibited in vitro activity against all tested isolates of vancomycin-susceptible, but not against vancomycin-resistant enterococci; activity was observed in both the planktonic and biofilm states.     

Activity of omadacycline tested against Streptococcus pneumoniae from a global surveillance program (2014)

The activity of omadacycline and comparators when tested against a subset of Streptococcus pneumoniae from US and European regions of a 2014 global surveillance program (304 isolates) are reported. These MIC results were compared to those obtained when testing S. pneumoniae from 2010 surveillance (1,834 isolates). The omadacycline MIC_50/90 for S. pneumoniae (2014) was 0.06/0.06 μg/mL, similar to 2010 (MIC_50/90, 0.06/0.12 μg/mL). The omadacycline MIC₉₀ (0.06–0.12 μg/mL) was similar for the penicillin-susceptible, -intermediate, -resistant, multidrug-resistance (MDR; ≥3 classes), and ceftriaxone nonsusceptible subgroups. Omadacycline MIC₉₀ values were 0.06–0.12 μg/mL for S. pneumoniae from the US and Europe. There was a high degree of resistance with doxycycline, erythromycin and trimethoprim-sulfamethoxazole in both US and EU. For penicillin-resistant S. pneumoniae, resistance to doxycycline and tetracycline in US/Europe was 64.2/61.0% and 63.8/60.5%, respectively, erythromycin 91.2/75.1, and ceftriaxone 7.3/4.0%. The potent activity of omadacycline against S. pneumoniae indicates that omadacycline merits further study in bacterial pneumonia, especially where MDR may be a concern.     

Anti-protozoal activity of diamine derivatives

Ten N-monoalkylated diamines were synthesized and evaluated for in vitro activities against Trichomonas vaginalis and Giardia lamblia. Several compounds displayed a good inhibition of parasite growth, with MIC less or equal to 20 μg/mL. N-hexadecil-1,4-butanediamine was found to be the most active compound in vitro against T. vaginalis with MIC of 2.5 μg/mL, twice more active in comparison to the reference drug metronidazole (MTZ). Seven of the studied compounds showed a better anti-G. lamblia activity than MTZ.     

Evaluation of anti-diabetic and anti-tumoral activities of bioactive compounds from Phoenix dactylifera L’s leaf: In vitro and in vivo approach

Among various chronic disorders, cancer and diabetes mellitus are the most common disorders. This study was designed to evaluate the effectiveness of hydroalcoholic extract of Phoenix dactylifera L. leaves (HEPdL) in animal models of type II diabetes in vitro/in vivo and in a human melanoma-derived cell line (IGR-39). A liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis was also performed to determine the amount of phenolic and flavonoid compounds in this plant. The physicochemical results by LC–MS/MS analysis of HEPdL showed the presence of 10 phenolic compounds. The in vitro study showed that the extract exhibited a more specific and potent inhibitor of α-glucosidase than α-amylase with an IC₅₀ value of 20 ± 1 μg/mL and 30 ± 0.8 μg/mL, respectively. More importantly, the in vivo study of the postprandial hyperglycemia activity with (20 mg/kg) of HEPdL showed a decrease in plasma glucose levels after 60 min in resemblance to the glucor (acarbose) (50 mg/kg) effect. The oral administration of HEPdL (20 mg/kg) in alloxan-induced diabetic mices for 28 days showed a more significant anti-diabetic activity than that of the drug (50 mg/kg). Moreover, cytotoxicity effects of HEPdL in IGR-39 cancer cell lines were tested by MTT assay. This extract was effective in inhibiting cancer cells growth (IGR-39) at dose 35 and 75 μg/mL. These results confirm ethnopharmacological significance of the plant and could be taken further for the development of an effective pharmaceutical drug against diabetes and cancer.     

Antileishmanial,antioxidant, and cytotoxic activities of Quercus infectoria Olivier extract

Currently, there is no effective vaccine available, and chemotherapy is the main approach for treatment of cutaneous leishmaniasis (CL). During recent decades, studies have demonstrated that a number of plant-derived compounds may act as new therapeutic tools against leishmaniasis. This study was evaluated the antileishmanial, antioxidant, and cytotoxic activities of Quercus infectoria Olivier (oak) extract. The total amount of phenolic and flavonoid compounds was measured in oak extract. High performance liquid chromatography (HPLC) analysis was also performed to determine the amount of quercetin and gallic acid in this plant. This extract (0–80 g/mL) was evaluated in vitro against promastigote and intracellular amastigote forms of Leishmania major (MRHO/IR/75/ER) using MTT assay and in a macro-phage model, respectively. Then oak extract was tested on CL in infected male BALB/c mice with L. major in order to evaluate the antileishmanial activity topically. Moreover, cytotoxicity effects of oak in murine macrophage cells were tested by MTT assay. Antioxidative activity of oak was also determined by the 2,2-diphenyl-1,1-picrylhydrazyl (DPPH) scavenging test. The amount of phenolic and flavonoid compounds in the oak extract was 57.50 and 1.86%, respectively. The amount of quercetin and gallic acid in the oak extract was 0.0064 and 0.22%, respectively. The findings revealed that oak significantly (P < 0.05) inhibited the growth rate of promastigote of (IC₅₀ 12.65 μg/mL) and amastigotes (IC₅₀ 10.31 μg/mL) as a dose-dependent response. In the in vivo assay, after 4 weeks of treatment, 91.6, 66.66, and 50% recovery was observed in the infected mice treated with 20, 10, and 5 mg/kg of oak extract, respectively. After treatment of the infected mice with the concentration of 10 and 20 mg/kg of oak, the mean diameter of lesions, parasite load and mean number of parasites was significantly (P < 0.05) reduced. Selectivity index of greater than 10 for oak revealed that oak extract had no cytotoxic effects on macrophage cells. Moreover, DPPH test demonstrated that radical inhibition occurred at greater power with increasing the concentration of oak. To conclude, the present study showed potent antileishmanial and antioxidant activity of oak extract; whereas this plant had no toxic effect on mammalian cells.     

Utility of salivary melatonin measurements in the assessment of the pineal physiology in newborn infants

SubjectsThe aim of this study was to assess whether salivary melatonin could be used as a reliable alternative to serum melatonin to study the pineal physiology in newborn infants.Design and methodsThe 95 newborn infants were allocated to four groups according to the time of sampling (09–11 am, 03–05 pm, 09–11 pm, and 03–05 am).ResultsThe median melatonin levels in serum and saliva were not significantly different between groups: median (interquartile range), 18.4 pg/mL (13.9–26.0 pg/mL) and 10.6 pg/mL (7.5–14.9 pg/mL); 13.3 pg/mL (11.5–19.0 pg/mL) and 9.1 pg/mL (7.8–14.2 pg/mL); 16.0 pg/mL (12.4–18.7 pg/mL) and 12.3 pg/mL (8.2–16.8 pg/mL); 13.0 pg/mL (8.8–27.4 pg/mL) and 11.2 pg/mL (7.7–16.6 pg/mL) for groups 1, 2, 3, and 4, respectively (p > 0.05). The results revealed a highly significant correlation between the serum and salivary melatonin levels (Pearson's correlation coefficient, r = 0.763; P < 0.001).ConclusionMelatonin levels in saliva reflect those in serum at any time of the day and like serum melatonin levels do not increase at night.     

Amelioratory effect of flavonoids rich Pergularia daemia extract against CFA induced arthritic rats

PurposePergularia daemia Forsk. (Asclepiadaceae) is a traditionally reported medicinal herb used to treat joint pain and arthritis. However, there are no scientific reports about anti-arthritic activity of P. daemia methanolic extract on rats as animal model. This study identifies bioactive compounds present in the P. daemia methanolic extract and evaluates its anti-arthritic potential in CFA induced arthritic rats.Methods and resultsPhytoconstituents of P. daemia extract were examined using LC-ESI/MS method. Anti-arthritic activity of P. daemia extract was determined by various biochemical experiments (RF, ESR and CRP), ultrasonography and histological analysis. LC-ESI/MS analysis resulted in the identification of major flavonoids compounds such as formononetin, qurecetin, chrysoeriol, taxifolin and naringenin. Serum biomarker analysis, after the treatment with PDME (500 mg/kg b.w.) revealed that the hemoglobin (11.84 ± 0.42 g/dL) and RBC (8.38 ± 0.67 million/mm³) levels were significantly increased whereas WBC (8.91 ± 0.38 thousands/mm³), RF (17.94 ± 0.45 IU/mL), ESR (7.91 ± 0.12 mm/h) and CRP (22.56 ± 0.26 mg/L) levels were decreased when compared with the CFA induced arthritic control group. Histology results revealed that treatment with PDME has resulted in significant prevention against bony destruction by decreasing soft tissue swelling and narrowing of joint spaces (250 and 500 mg/kg b.w.).ConclusionAnti-arthritic effect of P. daemia might be due to the presence of these bioactive flavonoids. These findings lend pharmacological support to the reported folkloric use of P. daemia in the treatment and management of painful, arthritic inflammatory conditions.     

Hair growth promoting activity of cedrol isolated from the leaves of Platycladus orientalis

Platycladus orientalis (L.) Franco is traditionally known to potentiate hair growth promotion. However, there has been no report on its main active ingredient responsible for the hair growth activity. In the current work, cedrol as a major constituent from P. orientalis was evaluated for its potential on hair growth in vivo. Different concentrations of cedrol (10, 20 and 30 mg/mL) were applied topically over the shaved skin of C57BL/6 mice and monitored for 21 days. Results indicated that cedrol significantly promoted hair growth in a dose-dependent manner, particularly for the female mice. Both male and female mice groups treated with 30 mg/mL cedrol required shorter time than the blank control and 2% minoxidil groups at different growth stages. Compared with the blank control (8.87 mm) and 2% minoxidil (9.94 mm) groups at 21 days, the hair length of female mice treated with 30 mg/mL cedrol showed a remarkable increase with the value of 11.07 mm. Hair in male and female mice groups treated with 30 mg/mL cedrol was heavier than the 2% minoxidil (38.2 and 35.9 mg, respectively) groups with the weight of 42.6 and 45.2 mg, respectively. Further observation of the hair follicle demonstrated that cedrol exerted a remarkable effect on the hair follicle length. These findings suggested that cedrol may be the main active ingredient of P. orientalis and have the potential of becoming a new hair growth promoter.     

Atrial natriuretic peptide stability

ObjectiveAtrial natriuretic peptide (ANP) is a key regulator in the homeostasis of water excretion and has emerged as an important prognostic marker for symptomatic chronic heart failure (CHF). The stability of ANP represents a crucial factor in assessing its use as a cardiac biomarker. Accordingly, we assessed the stability of ANP in blood samples collected from healthy controls and CHF subjects for a 12 month period.MethodsBlood samples from 10 healthy controls and 12 symptomatic CHF subjects with left ventricular systolic dysfunction were drawn. Determination of plasma ANP was performed by a standardized radioimmunoassay protocol.ResultsThe ANP levels of healthy subjects were 68.5 ± 11.6 pg/mL at baseline and 69.9 ± 17.2 pg/mL at 12 months (p = 0.71). The ANP concentrations of CHF subjects were 199.25 ± 44.8 pg/mL at baseline and 197.83 ± 47.4 pg/mL at 12 months (p = 0.70) respectively.ConclusionANP is a stable molecule with no evidence of degradation when stored at ? 80 °C.     

Bactericidal activity of garenoxacin against in vitro biofilm formed by nontypeable Haemophilus influenzae

Using β-lactamase-negative ampicillin (ABPC)-susceptible (BLNAS) and β-lactamase-negative ABPC-resistant (BLNAR) nontypeable Haemophilus influenzae (NTHi) strains isolated from otological patients, colony biofilm was prepared on membrane filter substrates. Bactericidal activities of garenoxacin (GRNX), levofloxacin (LVFX), cefditoren (CDTR), and clavulanic acid/amoxicillin (CVA/AMPC) were examined by counting viable cells after drug exposure to biofilm cells for 6 and 24 h and by observation under a scanning electron microscope (SEM). After exposure of biofilm to the 100-fold MIC of GRNX or LVFX for 24 h, GRNX and LVFX showed potent bactericidal activity (?log₁₀ CFU/ml, ≥5.1). In this case, the drug-exposure AUC, exposure concentration × 24 μg h/ml, was 64–128 % for GRNX and 121 % for LVFX of free AUC at the clinical dosage in humans, respectively. CDTR and CVA/AMPC at 100-fold MIC exhibited little bactericidal activity against biofilm cells. Under an SEM, after exposure of BLNAS and BLNAR biofilms to GRNX or LVFX, most of the biofilm matrices were transformed. Quinolones such as GRNX show potent bactericidal activity against biofilm-forming NTHi at the usual clinical dosage.     

Chemical composition,efficacy and safety of Pistacia vera (var. Fandoghi) to inactivate protoscoleces during hydatid cyst surgery

At present, various scolicidal agents have been used for inactivation of protoscoleces during hydatid cyst surgery, however, they are associated with serious adverse side effects including sclerosing colangititis (biliary tract fibrosis), liver necrosis and methaemoglobinaemia. This investigation was designed to evaluate the chemical composition and in vitro scolicidal effects of Pistacia vera (var. Fandoghi) essential oil against protoscoleces of hydatid cysts and also its toxicity in mice model. The components of the P. vera essential oil were identified by gas chromatography/mass spectroscopy (GC/MS) analysis. Protoscoleces were aseptically aspirated from sheep livers having hydatid cysts. Various concentrations of the essential oil (25–200 μl/mL) were used for 5–30 min. Viability of protoscoleces was confirmed using eosin exclusion test (0.1% eosin staining). In addition, forty male NIH mice were used to determine the acute and sub-acute toxicity of P. vera essential oil for 2 and 14 days, respectively. The main components of P. vera essential oil were limonene (26.21%), α-pinene (18.07%), α-thujene (9.31%) and α-terpinolene (9.28%). Findings of the present study demonstrated that the P. vera essential oil at the concentrations of 100 and 200 μl/mL killed 100% protoscoleces after 10 and 5 min of exposure, respectively. The LD₅₀ values of intraperitoneal injection of the P. vera essential oil was 2.69 ml/kg body weight, and the maximum nonfatal doses were 1.94 ml/kg body weight. No significant difference (P > 0.05) was observed in the clinical chemistry and hematological parameters following oral administrations of P. vera essential oil at the doses 0.1, 0.2, and 0.4 ml/kg for 14 days. The obtained findings demonstrated new chemical composition and promising scolicidal activity of the P. vera with no significant toxicity which might be used as a natural scolicidal agent in hydatid cyst surgery.     

In vitro activity of tedizolid against the Mycobacterium abscessus complex

Infections due to Mycobacterium abscessus carry a poor prognosis since this rapidly growing mycobacterium is intrinsically resistant to most antibiotics. Here, we evaluate the in vitro activity of the new oxazolidinone tedizolid against a collection of 44 M. abscessus clinical isolates. The MIC₅₀s and MIC₉₀s of tedizolid (2 and 8 μg/mL, respectively) were 2- to 16-fold lower than those of linezolid. There was no difference between the 3M. abscessus subspecies. Time-kill assays did not show any bactericidal activity at 4- and 8-fold the MIC. Combination of tedizolid with clarithromycin was synergistic against 1 out of 6 isolates, while indifferent interactions were observed for tedizolid combined with tigecycline, ciprofloxacin, and amikacin.     

Multicenter evaluation of the first automated Elecsys sFlt-1 and PlGF assays in normal pregnancies and preeclampsia

ObjectivesPerformance evaluation of Elecsys® sFlt-1 and PlGF assays.Design and methodsWithin-, between-run, total imprecision, functional sensitivity, inter-laboratory comparison, method comparison and lot-to-lot reproducibility were evaluated.ResultsWithin- and between-run CVs were below 4% for sFlt-1 > 60 and PlGF > 20 pg/mL. Total imprecision CVs were below 4.3%. Functional sensitivity was < 5 pg/mL. Inter-laboratory CVs were < 5%. Elecsys correlated well with Quantikine VEGF-R1 (r = 0.960) and PlGF (r = 0.968). Lot-to-lot comparisons yielded highly correlated results (r > 0.999).In healthy pregnancies, the median levels of sFlt-1 remained constant in first (1107 pg/mL) and second trimesters (1437 pg/mL) but increased in the third trimester (2395 pg/mL), while median PlGF levels increased in the first (30 pg/mL) and second trimesters (279 pg/mL) and peaked at 29 to 32 weeks (626 pg/mL) and decreased thereafter (340 pg/mL). The sFlt-1/PlGF ratio is highest in the first trimester (median: 28) but remained constant in the second (median: 4.7) and third trimesters (median: 5.1).In PE/HELPP samples matched for gestational age the sFlt-1 levels were significantly higher (6894–34,624 pg/mL), whereas PlGF levels were lower (9.2–80 pg/mL) and the median sFlt-1/PlGF ratio is much higher (461; range: 121–2614) than in apparently healthy pregnancies (3.6; range: 0.3–105).ConclusionThe new Roche Elecsys sFlt-1 and PlGF immunoassay showed excellent precision and reliability. There was a clear difference in the Elecsys sFlt-1/PlGF ratio between samples obtained from women with apparently normal pregnancy at the time of blood collection and those diagnosed with PE/HELLP at the same age of gestation.     

Correlation of haloperidol levels between saliva and plasma of acutely ill schizophrenic patients

ObjectiveClinical usefulness of monitoring haloperidol in salivary samples based on plasma:saliva correlation.Design and MethodsPlasma and saliva samples of schizophrenic patients [N = 105] were analyzed by highly sensitive reverse phase liquid chromatographic method to measure haloperidol at 240 nm using UV-PDA detector. Mobile phase consist of acetonitrile and water [50:50], pH 2.5 (0.1% acetic acid and 0.05 M KHPO₄) at flow rate 1.4 mL/min. Method was linear over 3–200 ng/mL.ResultsObserved therapeutic range was 5–19 ng/mL [11.66 ± 3.97] and 17–54 ng/mL [27.52 ± 11.51] for plasma and saliva respectively. Mean S:P was found to be 2.36.ConclusionCurrent study showed significantly high correlation [r = 0.93, p < 0.0001] between haloperidol levels in saliva and plasma with linear relationship. It is therefore concluded that monitoring of salivary concentration can be a clinically beneficial substitute. Patients showing clinical improvement [N = 90] were within salivary concentration range of 17–54 ng/mL, which can be an appropriate steady state monitoring range for haloperidol in saliva.     

Urine post equivalent daily cranberry juice consumption may opsonize uropathogenicity of Escherichia coli

Basic studies have proven that cranberries may prevent urinary tract infections through changing the adhesiveness of Escherichia coli (E. coli) to urothelial cells. Various cranberry preparations, including extract powder, capsules, and juice, have been shown to be effective in clinical and epidemiological research. Because cranberries are most commonly consumed as juice in a diluted concentration, the aim of this study was to investigate whether the equivalent daily dose of cranberry juice is sufficient to modify host urine to change the uropathogenicity of E. coli. Urine from rats taking an equivalent daily dose of cranberry juice has been shown to decrease the capability of E. coli in hemagglutination, urothelium adhesion, nematode killing, and biofilm formation. All these changes occurred after E. coli was incubated in cranberry metabolite-containing urine, defined as urine opsonization. Urine opsonization of E. coli resulted in 40.9 % (p = 0.0038) decrease in hemagglutination ability, 66.7 % (p = 0.0181) decrease in urothelium adhesiveness, 16.7 % (p = 0.0004) increase in the 50 % lethal time in killing nematodes, and 53.9 % (p = 5.9 × 10^?4) decrease in biofilm formation. Thus, an equivalent daily dose of cranberry juice should be considered sufficiently potent to demonstrate urine opsonization in E. coli.     

Diagnostic and prognostic value of serum procalcitonin concentrations in primary lung cancers

ObjectivesProcalcitonin (PCT) is widely used for the diagnosis of bacterial infections. The aim of this study was to evaluate PCT as a tumor and as a prognostic marker in patients with primary lung cancer.Design and methodsWe retrospectively performed a PCT dosage in the frozen serum samples of 147 patients with pulmonary neoplasia for whom a test of neuron-specific enolase (NSE) had been conducted at the time of diagnosis.ResultsWe show that a PCT serum level above 0.15 ng/mL was independently linked to the presence of a neuroendocrine component in the tumor (HR = 5.809 95% CI [1.695–19.908] p: 0005). Thus, median PCT serum levels were significantly more elevated in small-cell lung cancers than in pulmonary adenocarcinomas: 0.33 ng/mL versus 0.07 ng/mL (p < 0.001). However, the diagnostic value of serum PCT levels for diagnosing carcinoma with a neuroendocrine component remains low (sensitivity 63.8%; specificity 71.9%). In this series, serum PCT levels were significantly more elevated in the presence of liver metastases: 0.37 ng/mL versus 0.09 ng/mL in the absence of liver metastasis (p < 0.001). In uni- and multivariate analyses, a serum PCT level above 0.15 ng/mL and the presence of metastases and of sepsis at the time of diagnosis were independent factors of unfavorable prognosis.ConclusionsSerum PCT is elevated in patients with lung cancer with neuroendocrine component or with liver metastases. As a consequence, in this population, PCT has a poor specificity for bacterial infection. At diagnosis, an elevated serum PCT is an independent predictive factor of bad prognosis.     

Procalcitonin and C-reactive protein levels as diagnostic tools in febrile patients admitted to a General Internal Medicine ward

Objective: We study the extent to which procalcitonin (Pro-CT) and/or C-reactive protein (CRP) may be helpful in the early triage of febrile patients admitted to a general internal medicine ward.Methods: This is a prospective, observational study on 62 admitted patients in whom a temperature > 38 °C had been observed the day before inclusion.Results: Neither Pro-CT nor CRP was able to discriminate infectious (or bacterial) diseases from the other etiologies as a group, with an area under the ROC curve of 0.63 (95% CI 0.47–0.79, p = 0.15) for Pro-CT and 0.61, (95CI 0.44–0.78, p = 0.23) for CRP.Sensitivity and specificity for Pro-CT varied between 0.59 and 0.67 for a cut-off point of 0.2 ng/mL and 0.03 and 1 for a cut-off point of 10.0 ng/mL.However, in subgroup analysis, Pro-CT was able to discriminate between infectious and inflammatory diseases (Welch two sample t-test t = 2.39, df = 44.3, p = 0.021).     

Anserine inhibits carnosine degradation but in human serum carnosinase (CN1) is not correlated with histidine dipeptide concentration

BackgroundWe reported an association of a particular allele of the carnosinase (CNDP1 Mannheim) gene with reduced serum carnosinase (CN1) activity and absence of nephropathy in diabetic patients. Carnosine protects against the adverse effects of high glucose levels but serum carnosine concentration was generally low.MethodsWe measured the concentration of two further histidine dipeptides, anserine and homocarnosine, via HPLC. CN1 activity was measured fluorometically and for concentration we developed a capture ELISA.ResultsWe found an association between the CNDP1 Mannheim allele and reduced serum CN1 activity for all three dipeptides but no correlation to serum concentrations although anserine and homocarnosine inhibited carnosinase activity. Patients with liver cirrhosis have low CN1 activity (0.24 ± 0.17 μmol/ml/h, n = 7 males; normal range: 3.2 ± 1.1, n = 104; p < 0.05) and CN1 concentrations (2.3 ± 1.5 μg/ml; normal range: 24.9 ± 8.9, p < 0.05) but surprisingly, histidine dipeptide concentrations in serum are not increased compared to controls.ConclusionsSerum histidine dipeptide concentrations are not correlated to CN1 activity. The protective effect of low CN1 activity might be related either to turnover of CN1 substrates or a protective function of dipeptides might be localized in other tissues.     

Influence of pre-analytical and analytical factors on osteoprotegerin measurements

IntroductionOsteoprotegerin (OPG), an osteoclastogenesis inhibitor implicated in bone remodelling, has emerged as a potential biomarker for cardiovascular disease. In order to implement OPG determination in the clinical laboratory, it is crucial to identify the most appropriate specimen type, preparation and measurement conditions. The present study focuses on identifying the pre-analytical variables that may influence OPG measurements.MethodsSerum and plasma (in EDTA, heparin and citrate) were collected from 45 healthy volunteers (men (n = 21, 46.7%), women (n = 24, 53.3%)). OPG was analysed by ELISA. The influence of the centrifugation speed, the number of freeze–thaw cycles, delay in sample processing, thermo-stability and endogenous interfering agents (haemolysis, triglycerides, bilirubin, cholesterol and RANKL) were studied.ResultsOPG concentrations were significantly lower (p < 0.0001) in serum (1015 ± 357 pg/mL) than in all plasma samples (1314 ± 448 pg/mL in EDTA, 1209 ± 417 pg/mL in heparin and 1260 ± 498 pg/mL in citrate).Increasing centrifugation speed (200 g to 3000 g) did not change serum OPG concentration (p = 0.88). However, OPG concentration significantly increased when centrifuged serum samples were stored at 48 h at room temperature (p < 0.0001). Repeated freeze–thaw cycles did not modify OPG levels until 4 cycles (p < 0.0001). Increasing time before processing the samples (2 h and 6 h) raised OPG concentrations both at room temperature (p < 0.0001) or 4 °C (p < 0.001).Positive concentration-dependent interference of triglycerides was found in the analysed pooled samples; however, OPG concentrations were falsely diminished with haemoglobin interference. Bilirubin, cholesterol and RANKL did not interfere with OPG measurements.