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  • Similarly Dilma et al tried to assess the diagnostic

    2024-04-12

    Similarly Dilmaç et al. [16] tried to assess the diagnostic value of adenosine deaminase activity in sputum of patients with pulmonary tuberculosis, their aim was to determine and compare sputum ADA activity in pulmonary tuberculosis, lung cancer and chronic obstructive pulmonary disease (COPD) patients in order to assess its diagnostic value. Dilmaç et al. [16] found that sputum ADA activities in tuberculous group were significantly higher than the other two groups (P<0.01 for lung cancer group, P<0.05 for COPD) and this coincide with our findings. Also there was a significant increase in serum ADA activities in tuberculous patients than bronchogenic carcinoma and chronic obstructive pulmonary disease patients (P<0.05) and this also coincide with the present study. In Thonzonium Bromide to our result, Boonsarngsuk et al. [17] found that BALF ADA had limited value in differentiating pulmonary TB from some other pulmonary diseases. To differentiate TB from solid tumor without endobronchial obstruction, a combination of BALF ADA and TB PCR had marked additive diagnostic value. In the current study the cut off value of sputum ADA was 93.4IU/L, if the value was more than this cut off value the disease was present by 100.0%, while if the value was less than 93.4U/L, the disease was absent by about 93.2%, i.e. the sensitivity of this marker was 100.0%, specificity was 93.2%, positive predictive value was 95% and negative predictive value was 90%. On the other hand the cut off value of serum ADA was 17.9U/L, if the value was more than this cut off value the disease was present by 93.3%, while if the value was less than 17.9U/L, the disease was absent by about 51.0%, the sensitivity of this marker was 93.3%, specificity was 51.0%, positive predictive value was 62% and negative predictive value was 88%. Dimakou et al. [14] used a cut-off level of 16U/L and 5U/L respectively for sputum total ADA and ADA2, sensitivity and specificity were 55.6% and 100% for total ADA and 81.5% and 63.2% for ADA2.
    Conclusion
    Recommendation
    Introduction Adenosine deaminase (ADA, EC 3.5.4.4) catalyzes the irreversible deamination of adenosine to inosine and ammonia. This enzyme has been found in a wide variety of microorganisms, plants, invertebrates and mammals. It is an indispensable enzyme in purine metabolism. In humans, this enzyme is required for B and T-cell development and plays a central role in the maintenance of a competent immune system [1]. Genetic deficiency of ADA results in a disease known as severe combined immunodeficiency disease (SCID), which is characterized by a lack of T- and B-lymphocytes. Children with this disease have no detectable lymphocytes and are subject to recurrent infections [2]. The crystal structure of murine ADA shows that this protein is a zinc metalloenzyme that displays a typical αβ-barrel fold, with eight central β-strands and eight peripheral α-helices [3]. In addition to this central motif, the structure contains five additional α-helices. The catalytic mechanism of deamination has been suggested to proceed by the direct water attack on the C-6 position of the purine ring, resulting in the formation of a tetrahedral intermediate [4] (Fig. 1). Thus, 6-hydroxyl-1,6-dihydropurine riboside (HDPR) and the naturally occurring nucleoside antibiotic, 2′-deoxycoformycin, whose structures mimic the hypothetical tetrahedral transition state intermediate, bind tightly to the enzyme, with Ki of 10−13 and 10−12M, respectively. Adenine deaminase (ADE) and AMP deaminase are enzymes mechanistically related to ADA. ADE is also involved in the purine salvage pathway by deamination of adenine to hypoxanthine and ammonia. AMP deaminase catalyzes the formation of IMP and ammonia from AMP and is involved in regulating adenine nucleotide levels in eukaryotes [5]. Recent phylogenic analysis of amino acid sequences of various gene products suggests that ADAs, ADEs, AMP deaminases, adenosine deaminase-like (ADAL), and adenosine deaminase-related growth factors (ADGF) are a group of proteins that belong to the adenyl-deaminase family [6]. Members of this family share a novel motif consisting of methionine (or iso/leucine), proline, lysine and glycine (MPKG). In addition to this novel motif, the catalytically active residues are highly conserved in all five protein subfamilies.