Serum adenosine deaminase levels in pancreatic diseases

Changes of adenosine deaminase activity in serum and saliva around parturition in sows with and without postpartum dysgalactia syndrome

BACKGROUND

Postpartum dysgalactia syndrome (PDS) is associated with a significantly higher activation of the inflammatory and stress response at parturition than in the healthy sow. Therefore, reliable and possibly non-invasive biomarkers for substantial increases of inflammation are searched to support the PDS diagnosis. This report studies the possible changes of the inflammatory marker enzyme adenosine deaminase (ADA) in serum and saliva of 38 PDS positive sows (PDS+) and 38 healthy sows (PDS-). Sampling was performed every 24 h from 60 h before to 36 h after parturition. Isoenzyme 1 (ADA1) and isoenzyme 2 (ADA2), as well as total ADA (tADA), were measured and their statistical association with several serum and saliva biomarkers of inflammation and stress was investigated.

RESULTS

Compared to a baseline (60 to 36h prepartum), salivary activities of ADA1, ADA2 and tADA increased significantly over time in both PDS+ and PDS- sows, reaching their peaks after parturition. In serum from PDS- sows, no changes were observed over time in either ADA1, ADA2 or tADA. In PDS+ sows, serum ADA2 activity decreased temporarily after parturition followed by a significant increase compared to baseline. ADA1, ADA2 and tADA were all significantly associated with several inflammatory biomarkers and ADA1 in serum was associated with serum cortisol. Although serum activity was higher in PDS+ than in PDS- sows, the differences were not statistically significant. Further, no difference was noted between the groups in the analyses of saliva.

CONCLUSIONS

Salivary ADA1 and ADA2 increased in all sows after parturition, potentially as a response to the postpartum inflammation. However, no difference in the activity of ADA1, ADA2 and tADA were found between PDS+ and PDS- sows indicating inability to diagnose PDS under the conditions described in this report.

Adenosine deaminase inhibition

Adenosine deaminase is a critical enzyme in purine metabolism that regulates intra and extracellular adenosine concentrations by converting it to inosine. Adenosine is an important purine that regulates numerous physiological functions by interacting with its receptors. Adenosine and consequently adenosine deaminase can have pro or anti-inflammatory effects on tissues depending on how much time has passed from the start of the injury. In addition, an increase in adenosine deaminase activity has been reported for various diseases and the significant effect of deaminase inhibition on the clinical course of different diseases has been reported. However, the use of inhibitors is limited to only a few medical indications. Data on the increase of adenosine deaminase activity in different diseases and the impact of its inhibition in various cases have been collected and are discussed in this review. Overall, the evidence shows that many studies have been done to introduce inhibitors, however, in vivo studies have been much less than in vitro, and often have not been expanded for clinical use.

Split aptamer based sensing platform for adenosine deaminase detection by fluorescence resonance energy transfer

In this paper, a split aptamer based fluorescence resonance energy transfer (FRET) platform was constructed for the determination of adenosine deaminase (ADA) activity by using gold nanoclusters (AuNCs) and gold nanoparticles (AuNPs). A single adenosine triphosphate (ATP) aptamer was split into two fragments (referred to as P1 and P2). P1 was covalently attached to the AuNCs at the 5' end (P1-AuNCs), and P2 was labeled with AuNPs at the 3' end (P2-AuNPs). In the presence of ATP, ATP bound with the two fragments with high affinity to link P1-AuNCs and P2-AuNPs together, thus the fluorescence of P1-AuNCs was quenched via FRET from P1-AuNCs to P2-AuNPs. With the addition of ADA, ATP was transformed into inosine triphosphate (ITP), and then P1 and P2 were released to cause the fluorescence recovery of the system. So a split aptamer based FRET platform for ADA detection can be established via the fluorescence intensity change of the system. This platform showed a good linear relationship between the fluorescence intensity and ADA concentration in the range of 2-120 U L^-1, and the limit of detection (LOD) was 0.72 U L^-1. Moreover, the detection of ATP in human serum sample demonstrated the accuracy and applicability of the method for ADA detection in real sample.

Screening for Pancreatic Cancer: Current Status and Future Directions

Pancreatic ductal adenocarcinoma is a lethal disease for a multitude of reasons, including difficulty of early detection, early metastatic spread, and absence of more effective therapies. Even with the advent of newer systemic therapies, the 1-year survival for metastatic disease ranges from 17–23% and 5-year survival is <5%. This necessitates an urgent need for the development of more effective modalities for early detection, particularly due to the long latent period between the genomic cellular changes and the development of metastatic disease. Currently available biochemical and molecular markers have significant potential; however, they require further clinical validation. Endoscopic ultrasound is one of the most sensitive modalities used to both screen and sample lesions, but is limited to use in high-risk patients due to its invasive nature and associated risks. Although clinically meaningful progress has been made in screening the high-risk cohorts in terms of detection of pancreatic ductal adenocarcinoma, intraductal papillary mucinous neoplasms, and mucinous cystic neoplasms, leading to early diagnosis and treatment, nonselective population-based screening is not yet available for widespread use. Currently there is no consensus on the most appropriate screening protocol for early pancreatic cancer detection. In this review, we focus on understanding the potential role of molecular and radiogenomic markers in the early detection of pancreatic cancer.

Cattle naturally infected by Eurytrema coelomaticum: Relation between adenosine deaminase activity and zinc levels

The enzyme adenosine deaminase (ADA) is critical for modulating the immune system, and in the presence of zinc, its activity is catalyzed. The aim of this study was to evaluate the ADA activity in pancreas of cattle naturally infected by Eurytrema coelomaticum in relation to the results of zinc levels, pathological findings and parasite load. For this study 51 slaughtered cattle were used. The animals were divided into two groups: Group A consisting of animals naturally infected by E. coelomaticum (n=33) and Group B of uninfected animals (n=18). Blood and pancreas were collected of each animal for analysis of zinc and ADA, respectively. Infected cattle showed a reduction on seric levels of zinc, and decreased ADA activity in the pancreas (P>0.05). A positive correlation between zinc levels and ADA activity was observed. Thus, high parasite load and severity of histopathologic lesions affect the ADA activity in pancreas, as well as the zinc levels in serum of infected animals (negative correlation between these variables). Therefore, we can conclude that cattle infected by E. coelomaticum have low ADA activity in pancreas, which can be directly related to zinc reduction, responsible for ADA activation and catalyzes.

Purification and characterization of the enzymes involved in nicotinamide adenine dinucleotide degradation by Penicillium brevicompactum NRC 829

The present study was conducted to investigate a new pathway for the degradation of nicotinamide adenine dinucleotide (NAD) by Penicillium brevicompactum NRC 829 extracts. Enzymes involved in the hydrolysis of NAD, i.e. alkaline phosphatase, aminohydrolase and glycohydrolase were determined. Alkaline phosphatase was found to catalyse the sequential hydrolysis of two phosphate moieties of NAD molecule to nicotinamide riboside plus adenosine. Adenosine was then deaminated by aminohydrolase to inosine and ammonia. While glycohydrolase catalyzed the hydrolysis of the nicotinamide-ribosidic bond of NAD+ to produce nicotinamide and ADP-ribose in equimolar amounts, enzyme purification through a 3-step purification procedure revealed the existence of two peaks of alkaline phosphatases, and one peak contained deaminase and glycohydrolase activities. NAD deaminase was purified to homogeneity as estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis with an apparent molecular mass of 91 kDa. Characterization and determination of some of NAD aminohydrolase kinetic properties were conducted due to its biological role in the regulation of cellular NAD level. The results also revealed that NAD did not exert its feedback control on nicotinamide amidase produced by P. brevicompactum.

No association between serum adenosine deaminase activity and disease activity in Crohn's disease

BACKGROUND

Adenosine deaminase activity is proposed as a marker of inflammation in some inflammatory conditions.

AIMS

To investigate the association of serum adenosine deaminase activity and disease activity in Crohn's disease patients.

METHODS

In a cross-sectional study, 30 consecutive known cases of Crohn's disease (15 with active disease and 15 in remission) referring to a university hospital in Tehran (Iran) and 15 age- and gender-matched healthy controls were studied. Disease activity was assessed using the Crohn's disease activity index (cutoff >150). Total serum adenosine deaminase activity, C-reactive protein, erythrocyte sedimentation rate, and fecal calprotectin were evaluated in patients. Serum adenosine deaminase activity was measured in controls.

RESULTS

Mean age of the patients was 36.8 ± 12.6 years, and 56.7 % were male. Serum adenosine deaminase activity in patients with active disease, patients in remission, and controls was 12.3 ± 5.9, 14.6 ± 6.2, and 11.9 ± 6.4 U/L, respectively (P = 0.458). Compared with patients in remission, those with active disease had higher erythrocyte sedimentation rate (40.4 ± 30.6 vs. 16.9 ± 16.0 mm/h, P = 0.014) and higher frequency of positive C-reactive protein (66.6 vs. 13.3 %, P = 0.004) and positive fecal calprotectin tests (86.6 vs. 33.3 %, P = 0.004). Serum adenosine deaminase activity was not correlated with erythrocyte sedimentation rate (r = 0.05, P = 0.761) and was not different between patients with positive and negative C-reactive protein (12.2 ± 5.4 vs. 14.2 ± 6.5 U/L, P = 0.393) and fecal calprotectin tests (11.7 ± 5.3 vs. 16.0 ± 6.5 U/L, P = 0.063).

CONCLUSIONS

In patients with Crohn's disease, serum adenosine deaminase activity is not associated with clinical disease activity or with other inflammation markers and cannot be suggested as an inflammation marker.

Adenosine deaminase biosensor combining cationic conjugated polymer-based FRET with deoxyguanosine-based photoinduced electron transfer

We demonstrated a sensitive and selective adenosine deaminase (ADA) detection by modulating the fluorescence resonance energy transfer (FRET) between cationic conjugated poly(9,9-bis(6'-N,N,N-trimethylammonium) hexyl)fluorine phenylene) (PFP) and the deoxyguanosine-tailored hairpin aptamer. The hairpin aptamer was labeled with a fluorophore FAM at one end and three deoxyguanosines (Gs) at the other end as a quencher. In the absence of ADA, aptamer forms hairpin-like conformation with adenosines making close affinity of Gs and FAM, which results in the weak FRET from PFP to FAM because of FAM fluorescence being quenched by Gs via photoinduced electron transfer (PET). After addition of ADA, adenosine was hydrolyzed by ADA, followed by the release of free aptamer. In this case, FAM being far away from Gs, the strong FRET thus was obtained due to the quenching process being blocked. Therefore, the new strategy based on the FRET ratio enhancement is reasonably used to detect the ADA sensitively, combining the fluorescence signal amplification of conjugated polymers with the initiative signal decreasing by Gs. The detection limit of the ADA assay is 0.3 U/L in both buffer solution and human serum, which is more sensitive than most of those previously documented methods. Importantly, the assay is rapid, homogeneous, and simple without a complicated treating process. The ADA inhibitor, erythro-9-(2-hydroxy-3-nonyl) adenine hydrochloride (EHNA), was also studied based on this assay, and the detection limit of EHNA is 10 pM. This strategy provides a new platform for the detection of other biomolecules and enzymes.

Screening for pancreatic cancer

Even with improved cancer care generally, the incidence and death rate is increasing for pancreatic cancer. Concern exists that a further increase in deaths caused by pancreatic cancer will be seen as other causes of death, such as heart disease and other cancers, decline. Critical exploration of screening high-risk patients as a tool to reduce deaths from pancreatic cancer should be considered. Technological advances and improved understanding of pancreatic cancer biology provides an opportunity to identify and test a panel of early detection biomarkers easily, accurately, and inexpensively measured in blood, urine, stool, or saliva samples. These biomarkers may have additional usefulness in staging, stratification for treatment, establishing prognosis, and assessing response to therapy in this disease. Screening may prove to be one of several strategies to improve outcomes in a disease that has otherwise been difficult to defeat.

Purification and partial characterization of NAD aminohydrolase from Aspergillus oryzae NRRL447

Aspergillus oryzae aminohydrolase free acid phosphodiesterase catalyzes nicotinamide adenine dinucleotide to deamino-NAD and ammonia. The enzyme was purified to homogeneity by a combination of acetone precipitation, anion exchange chromatography and gel filtration chromatography. The enzyme was purified 230.5 fold. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme showed a single protein band of MW 94 kDa. The enzyme displayed maximum activity at pH 5 and 40 °C with NAD as substrate. The enzyme activity appeared to be stable up to 40 °C. The enzyme activity was enhanced slightly by addition of Na⁺ and K⁺, whereas inhibited strongly by addition of Ag⁺, Mn²⁺, Hg²⁺ and Cu²⁺ to the reaction mixtures. The enzyme hydrolyzes several substrates, suggesting a probable non-specific nature. The enzyme catalyzes the hydrolytic cleavage of amino group of NAD, adenosine, AMP, CMP, GMP, adenosine, cytidine and cytosine to the corresponding nucleotides, nucleosides or bases and ammonia. The substrate concentration-activity relationship is the hyperbolic type and the apparent Km and Kcat for the tested substrates were calculated.

Screening for pancreatic cancer: why, how, and who?

Pancreatic cancer is the fourth most common cause of cancer mortality in the United States, with 5-year survival rates for patients with resectable tumors ranging from 15% to 20%. However, most patients presenting with distant metastases, are not resectable, and have a 5-year survival rate of close to 0%. This demonstrates a need for improved screening to identify pancreatic cancer while the tumor is still localized and amenable to surgical resection. Studies of patients with pancreatic tumors incidentally diagnosed demonstrate longer median survival than tumors discovered only when the patient is symptomatic, suggesting that early detection may improve outcome. Recent evidence from genomic sequencing indicates a 15-year interval for genetic progression of pancreatic cancer from initiation to the metastatic stage, suggesting a sufficient window for early detection. Still, many challenges remain in implementing effective screening. Early diagnosis of pancreatic cancer relies on developing screening methodologies with highly sensitive and specific biomarkers and imaging modalities. It also depends on a better understanding of the risk factors and natural history of the disease to accurately identify high-risk groups that would be best served by screening. This review summarizes our current understanding of the biology of pancreatic cancer relevant to methods available for screening. At this time, given the lack of proven benefit in this disease, screening efforts should probably be undertaken in the context of prospective trials.

Serum adenosine deaminase activity as a predictor of disease severity in ulcerative colitis

BACKGROUND AND AIM

Ulcerative colitis (UC) is a chronic inflammatory disease characterized by recurrent inflammation and ulcerations of colonic mucosa and an inappropriate and delayed healing. Adenosine deaminase (ADA) is a cytoplasmic enzyme involved in the catabolism of purine bases, capable of catalyzing the deamination of adenosine, forming inosine in the result process. Although ADA has been shown to increase in several inflammatory conditions, there are no literature data indicating an alteration in UC.

METHODS

This study evaluated the activity of total ADA in serum of 43 patients with UC and 18 healthy controls. Patients' age, disease duration, drug intake, and other medical history were all noted for each subject. Complete blood count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were determined for both patients and controls. Correlation analysis was also performed between ADA and other inflammation markers of UC.

RESULTS

Serum mean ADA levels were 11.12 ± 2.03 and 7.99 ± 2.04 U/l for patients with UC in active state and in remission and 8.55 ± 2.26 U/l in the healthy control group. Mean serum ADA levels were significantly elevated in active UC patients compared with patients with UC in remission and control groups. Overall accuracy of ADA in determination of active UC was 83.7 with sensitivity 83.3%, specificity 84.2%.

CONCLUSIONS

Serum ADA levels were found to be elevated in UC patients in active state suggesting a partial role of activated T-cell response in the disease pathophysiology. Further randomized controlled studies are warranted to demonstrate the role of ADA in UC patients, with a special interest in specifically targeted therapies against ADA for achieving disease remission.

Elevated adenosine deaminase levels in celiac disease

Celiac disease (CD) is a genetically based chronic inflammatory disorder of the small bowel induced by the dietary gluten and possibly other environmental cofactors. The objective of this study was to investigate the relation of adenosine deaminase (ADA), a cytoplasmic enzyme involved in the catabolism of purine bases, as an index of altered immune response, with adult CD patients. ADA has been shown to increase in several inflammatory conditions, but there is no literature data indicating an alteration in CD. Serum levels of ADA were investigated in newly diagnosed 20 CD patients. ADA levels were compared in patients with CD and in healthy controls. Correlation analysis was also performed between ADA and other serum markers of CD (anti-gliadin and anti-endomysial antibodies) Mean serum ADA levels were significantly elevated in CD patients compared with control group. ROC curve analysis suggested that the optimum ADA level cut-off point for CD was 12.27 U/l. At a cut-off value of 12.27 U/l, the sensitivity was 80% and specificity was 100%. There was no statistically significant correlation between ADA and anti-gliadin and anti-endomisium antibodies. Serum ADA levels elevated significantly in CD patients, suggesting a partial role in activated T-cell response in the disease pathophysiology. ADA can be used as a supportive diagnostic marker in patients with CD.

The blockade of adenosine deaminase ameliorates chronic experimental colitis through the recruitment of adenosine A2A and A3 receptors

Adenosine modulates immune/inflammatory reactions. This study investigates the expression of adenosine deaminase in the inflamed colon, the effects of adenosine deaminase inhibitors on established colitis, and the recruitment of adenosine receptors by endogenous adenosine after adenosine deaminase blockade. Adenosine deaminase expression was determined by Western blot. The effects of 4-amino-2-(2-hydroxy-1-decyl)pyrazole[3,4-d]pyrimidine (APP; a novel adenosine deaminase inhibitor), erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA; a reference adenosine deaminase inhibitor), dexamethasone, and selective adenosine receptor antagonists were tested in rats with 2,4-dinitrobenzenesulfonic acid-induced colitis. Systemic (food intake, body and spleen weight) and colonic [macroscopic/microscopic damage, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and malondialdehyde (MDA)] inflammatory parameters were assessed. Test drugs were administered intraperitoneally for 6 days, starting at day 5 from colitis induction. Adenosine deaminase was detected in normal colon, and its expression was increased in inflamed tissues. Colitis was associated with decreased food intake and body weight, augmented spleen weight, and increased levels of colonic TNF-α, IL-6, and MDA. APP or EHNA, but not dexamethasone, improved food intake and body weight. APP, EHNA, and dexamethasone counteracted the increments of spleen weight, ameliorated macroscopic and microscopic indexes of inflammation, and reduced TNF-α, IL-6, and MDA levels. The beneficial effects of APP and EHNA on inflammatory parameters were prevented by the pharmacological blockade of A(2A) or A(3) receptors, but not A(1) or A(2B). The present results show that: 1) bowel inflammation is associated with an enhanced adenosine deaminase expression; and 2) the anti-inflammatory actions of adenosine deaminase inhibitors against chronic established colitis depend on the sparing of endogenous adenosine, leading to enhanced A(2A) and A(3) receptor activation.

Evaluation of cerebrospinal fluid adenosine deaminase activity in HIV-seropositive subjects and its association with lactate dehydrogenase and protein levels

The purpose of this study was to investigate the role of ADA as additional marker of HIV infection as well as its association with other biochemical markers. This study included 55 patients, 26 being diagnosed as HIV positive and 29 patients diagnosed as HIV negative. Glucose, total protein, lactate dehydrogenase, and adenosine deaminase (ADA) activity were measured on cerebrospinal fluid (CSF). ADA activity on CSF was statistically different in HIV-seropositive subjects compared with HIV-negative subjects. The sensitivity and specificity of ADA activity on CSF was 50 and 82.76%, respectively. ADA activity was positively correlated with lactate dehydrogenase and protein in patients with HIV positive and it was negatively correlated with glucose levels. ADA determination in CSF could add information about inflammatory processes in patients with HIV infection.

Improved diagnosis of pancreatic adenocarcinoma using haptoglobin and serum amyloid A in a panel screen

BACKGROUND

Timely, accurate diagnosis of pancreatic adenocarcinoma (PA) is hampered by the lack of effective circulating biomarkers. No single test has emerged that improves upon the commonly used biomarker cancer antigen 19-9 (CA 19-9) to discriminate PA from benign conditions effectively. The goals of this study were to validate two acute-phase proteins, haptoglobin and serum amyloid A (SAA), as biomarkers for PA and determine if the combination of haptoglobin, SAA, and CA 19-9 would improve PA diagnosis over CA 19-9 alone.

METHODS

Levels of haptoglobin, SAA, and CA 19-9 were measured in pretreatment sera from 75 PA patients, 32 patients with chronic pancreatitis, 42 patients with other benign pancreatic disease or biliary stricture, and 150 healthy control subjects by enzyme-linked immunosorbent assay or colorimetric binding assay. Relative levels of haptoglobin or SAA were compared between groups using analysis of variance. The diagnostic accuracy of serum haptoglobin and SAA levels were investigated using receiver operating characteristics (ROC) analysis. Using classification tree analysis, an algorithm was developed that used haptoglobin, SAA, and CA 19-9 in a diagnostic screening panel.

RESULTS

Both haptoglobin and SAA were significantly elevated in sera from PA patients compared to healthy control subjects (p<0.0001) and patients with chronic pancreatitis (p=0.01). Haptoglobin was significantly elevated in sera from PA patients relative to patients with other benign diseases (p=0.0015), whereas SAA fell short of significance in the same comparison (p=0.0508). ROC analysis indicated that haptoglobin [area under the curve (AUC)=0.792] was a better diagnostic marker than SAA (AUC=0.691) over multiple threshold cutoffs. Using specific cutoffs that minimized overall misclassification, haptoglobin yielded a sensitivity of 82.7% and a specificity of 71.1%, and SAA yielded a sensitivity of 34.7% and a specificity of 90.2% when discriminating PA cases from all non-PA controls. In the same sample set, CA 19-9 yielded a sensitivity of 77.3% and a specificity of 91.1%. Combining data from haptoglobin, SAA, and CA 19-9 in a diagnostic screening panel improved the overall accuracy when compared to CA 19-9 alone, yielding a sensitivity of 81.3% and a specificity of 95.5%.

CONCLUSIONS

These data demonstrate that haptoglobin and SAA are useful for discriminating PA from benign conditions as well as healthy controls when used in a diagnostic screening panel. This study supports the use of combined biomarkers for improved accuracy in the diagnosis of PA.