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Potential toxic effects of chlorination and UV/chlorination in the treatment of hydrochlorothiazide in the water

Mansor NA, Tay KS

Sci Total Environ, 2020 Apr 20;714:136745.
PMID: 31982754 DOI: 10.1016/j.scitotenv.2020.136745

Chlorination is a common disinfection method in water treatment. This method can be converted into an advanced oxidation process by incorporating UV irradiation during water treatment. This study investigated the degradation of hydrochlorothiazide (HCTZ) by chlorination and UV/chlorination in water. HCTZ is a diuretic medication that has been frequently detected in wastewater. For chlorination, the second-order rate constant for the reaction between HCTZ with free available chlorine was found to increase with increasing pH from 5 to 8 due to the increase of the anionic HCTZ fraction. UV/chlorination was found to be more efficient in removing HCTZ as compared with chlorination due to the presence of reactive radical species such as hydroxyl radicals. For transformation by-products, chlorination was found to produce two by-products via chlorination and hydroxylation reactions that occurred at the aromatic ring of HCTZ. For UV/chlorination, an additional by-product formed through a radical reaction at the heterocyclic moiety of HCTZ was detected. Based on the Escherichia coli inhibition study, chlorination and UV/chlorination were found to increase the toxicity of the HCTZ solution. This result indicated that even UV/chlorination showed higher effectiveness in removing HCTZ; however, it also has the potential to generate toxic by-products and effluent.
Degradation of 5,5-diphenylhydantoin by chlorination and UV/chlorination: kinetics, transformation by-products, and toxicity assessment

Mansor NA, Tay KS

Environ Sci Pollut Res Int, 2017 Oct;24(28):22361-22370.
PMID: 28801887 DOI: 10.1007/s11356-017-9892-6

This study investigated the reaction kinetics and mechanism of the degradation of 5,5-diphenylhydantoin (DPH) during conventional chlorination and UV/chlorination. DPH is one of the antiepileptic drugs, which has frequently been detected in the aquatic environment. For chlorination, the second-order rate constant for the reaction between DPH and free active chlorine (FAC) was determined at pH 5 to 8. At pH 6 to 8, the efficiency of chlorination in the removal of DPH was found to be dominated by the reaction involving hypochlorous acid (HOCl). The result also showed that anionic species of DPH was more reactive toward FAC as compared with neutral DPH. For UV/chlorination, the effect of FAC dosage and pH on the degradation of DPH was evaluated. UV/chlorination is a more effective method for removing DPH as compared with conventional chlorination and UV irradiation. The DPH degradation rate was found to increase with increasing FAC concentration. On the other hand, the degradation of DPH was found to be more favorable under the acidic condition. Based on the identified transformation by-products, DPH was found to be degraded through the reaction at imidazolidine-2,4-dione moiety of DPH for both chlorination and UV/chlorination. Toxicity study on the chlorination and UV/chlorination-treated DPH solutions suggested that UV/chlorination is a more efficient method for reducing the toxicity of DPH.
Myelodysplastic syndrome with fibrosis and complex karyotype arising in a patient with essential thrombocythaemia

Mansor NA, Yusof N, Tang YL, Ithnin A, Azma RZ, Tumian NR, et al.

Malays J Pathol, 2018 Aug;40(2):191-197.
PMID: 30173238 MyJurnal

INTRODUCTION: Essential thrombocythaemia (ET) is a chronic myeloproliferative neoplasm (MPN) characterised by persistent thombocytosis. It is an indolent disorder but transformation to myelofibrosis (MF), acute myeloid leukaemia (AML) or myelodyplastic syndrome (MDS) has been reported.
CASE REPORT: We described a patient with ET whose disease evolved into MDS with fibrosis and complex karyotype after 15 years of stable disease. She was asymptomatic and was on hydroxyurea (HU) treatment until recently when she presented with worsening anaemia. Physical examination showed mild splenomegaly. Full blood picture showed leukoerythroblastic picture with presence of 3% circulating blasts and background of dysplastic features such as hypogranular cytoplasm and nuclear hyposegmentation of neutrophils. The bone marrow aspiration was haemodiluted but revealed presence of 6% blast cells, trilineage dysplasia and predominant erythroid precursors (60%). Trephine biopsy showed no excess of blast cells and normal quantity of erythroid precursors, but there was increased in fibrosis (WHO grade 2) and presence of dysmegakaryopoeisis such as nuclear hypolobation, multinucleation and micromegakaryocytes. Cytogenetic study showed complex karyotype; monosomy of chromosome 2, chromosome 5, chromosome 18 and presence of a marker chromosome (42~44, XX,-2,-5,-18,+mar). Fluorescence in situ hybridisation (FISH) showed 5q deletion (CSF1R and EGR1).
CONCLUSION: The findings were consistent with transformation of ET to MDS with fibrosis and complex karyotype. ET progression to MDS is considered rare. The presence of complex karyotype and fibrosis in MDS are associated with unfavourable outcome.
Role of phIGFBP-1 and ultrasound cervical length in predicting pre-term labour

Azlin MI, Bang HK, An LJ, Mohamad SN, Mansor NA, Yee BS, et al.

J Obstet Gynaecol, 2010;30(5):456-9.
PMID: 20604646 DOI: 10.3109/01443615.2010.489162

This prospective observational study was to evaluate the efficacy of combining phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) and transvaginal ultrasound cervical length (CL) compared with either indicator alone in predicting pre-term labour (PTL). Women with singleton pregnancy between 24 and 36 weeks' gestation with evidence of PTL were subjected to phIGFBP-1 and CL tests. Of the 51 women, five were tested positive (phIGFBP-1 positive and CL <2.5 cm) for combination of phIGFBP-1 and CL (four delivered within 1 week), whereas 46 tested negative, of which, only one delivered. A much higher negative predictivity (NP), positive predictivity (PP) and specificity (SP) in the combination test was seen compared with phIGFBP-1 or CL alone (NP: 97.8% vs 97.7% vs 97.1%; PP: 80.0% vs 51.1% and CL 23.5%; SP: 97.8% vs 93.5% vs 71.1%, respectively). The cervical os dilatation of 2 cm with combined positive test (p = 0.001) indicated a higher likelihood of PTL.