The Role of N-Acetylcysteine Supplementation on the Oxidative Stress Levels, Genotoxicity and Lineage Commitment Potential of Ex Vivo Murine Haematopoietic Stem/Progenitor Cells

Objectives

The ex vivo maintenance of haematopoietic stem/progenitor cells (HSPCs) is crucial to ensure a sufficient supply of functional cells for research or therapeutic applications. However, when exposed to reactive oxygen species (ROS) in a normoxic microenvironment, HSPCs exhibit genomic instability which may diminish their quantity and quality. This study aimed to investigate the role of N-acetylcysteine (NAC) supplementation on the oxidative stress levels, genotoxicity and lineage commitment potential of murine haematopoietic stem/progenitor cells (HSPCs).

Methods

This study was carried out at the Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia, between June 2016 and July 2017. Bone marrow cells were isolated from nine mice and cultured in a growth medium. Various concentrations of NAC between 0.125-2 μM were added to the culture for 48 hours; these cells were then compared to non-supplemented cells harvested from the remaining three mice as the control group. A trypan blue exclusion test was performed to determine cell viability, while intracellular ROS levels and genotoxicity were determined by hydroethidine staining and comet assay, respectively. The lineage commitment potential of erythroid, myeloid and pre-B-lymphoid progenitor cells was evaluated via colony-forming cell assay.

Results

NAC supplementation at 0.25, 0.5 and 2 μM significantly increased cell viability (P <0.050), while intracellular ROS levels significantly decreased at 0.25 and 0.5 μM (P <0.050). Moreover, DNA damage was significantly reduced at all NAC concentrations (P <0.050). Finally, the potential lineage commitment of the cells was not significantly affected by NAC supplementation (P >0.050).

Conclusion

The findings of this study indicate that NAC supplementation may potentially overcome the therapeutic limitations of ex vivo-maintained HSPCs.

Tocotrienol-rich fraction from palm oil prevents oxidative damage in diabetic rats

OBJECTIVES

This study was carried out to determine the effects of tocotrienol-rich fraction (TRF) (200 mg/Kg) on biomarkers of oxidative stress on erythrocyte membranes and leukocyte deoxyribonucleic acid (DNA) damage in streptozotocin (STZ)-induced diabetic rats.

METHODS

Male rats (n = 40) were divided randomly into four groups of 10: a normal group; a normal group with TRF; a diabetic group, and a diabetic group with TRF. Following four weeks of treatment, fasting blood glucose (FBG) levels, oxidative stress markers and the antioxidant status of the erythrocytes were measured.

RESULTS

FBG levels for the STZ-induced diabetic rats were significantly increased (P <0.001) when compared to the normal group and erythrocyte malondialdehyde levels were also significantly higher (P <0.0001) in this group. Decreased levels of reduced glutathione and increased levels of oxidised glutathione (P <0.001) were observed in STZ-induced diabetic rats when compared to the control group and diabetic group with TRF. The results of the superoxide dismutase and glutathione peroxidase activities were significantly lower in the STZ-induced diabetic rats than in the normal group (P <0.001). The levels of DNA damage, measured by the tail length and tail moment of the leukocyte, were significantly higher in STZ-induced diabetic (P <0.0001). TRF supplementation managed to normalise the level of DNA damage in diabetic rats treated with TRF.

CONCLUSION

Daily supplementation with 200 mg/Kg of TRF for four weeks was found to reduce levels of oxidative stress markers by inhibiting lipid peroxidation and increasing the levels of antioxidant status in a prevention trial for STZ-induced diabetic rats.

The role of oxidative stress and antioxidants in diabetic complications

Diabetes is considered to be one of the most common chronic diseases worldwide. There is a growing scientific and public interest in connecting oxidative stress with a variety of pathological conditions including diabetes mellitus (DM) as well as other human diseases. Previous experimental and clinical studies report that oxidative stress plays a major role in the pathogenesis and development of complications of both types of DM. However, the exact mechanism by which oxidative stress could contribute to and accelerate the development of complications in diabetic mellitus is only partly known and remains to be clarified. On the one hand, hyperglycemia induces free radicals; on the other hand, it impairs the endogenous antioxidant defense system in patients with diabetes. Endogenous antioxidant defense mechanisms include both enzymatic and non-enzymatic pathways. Their functions in human cells are to counterbalance toxic reactive oxygen species (ROS). Common antioxidants include the vitamins A, C, and E, glutathione (GSH), and the enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GRx). This review describes the importance of endogenous antioxidant defense systems, their relationship to several pathophysiological processes and their possible therapeutic implications in vivo.

Abnormal folate metabolism and genetic polymorphism of the folate pathway in a child with Down syndrome and neural tube defect

The association of neural tube defects (NTDs) with Down syndrome (trisomy 21) and altered folate metabolism in both mother and affected offspring provide a unique opportunity for insight into the etiologic role of folate deficiency in these congenital anomalies. We describe here the case of a male child with trisomy 21, cervical meningomyelocele, agenesis of corpus callosum, hydrocephaly, cerebellar herniation into the foramen magnum, and shallow posterior cranial fossa. Molecular analysis of the methylenetetrahydrofolate (MTHFR) gene revealed homozygosity for the mutant 677C-->T polymorphism in both the mother and child. The plasma homocysteine of the mother was highly elevated at 25.0 micromol/L and was associated with a low methionine level of 22.1 micromol/L. Her S-adenosylhomocysteine (SAH) level was three times that of reference normal women, resulting in a markedly reduced ratio of S-adenosylmethionine (SAM) to SAH and significant DNA hypomethylation in lymphocytes. The child had low plasma levels of both homocysteine and methionine and a reduced SAM/SAH ratio that was also associated with lymphocyte DNA hypomethylation. In addition, the child had a five-fold increase in cystathionine level relative to normal children, consistent with over-expression of the cystathionine beta synthase gene present on chromosome 21. We suggest that altered folate status plus homozygous mutation in the MTHFR gene in the mother could promote chromosomal instability and meiotic non-disjunction resulting in trisomy 21. Altered folate status and homozygous TT mutation in the MTHFR gene in both mother and child would be expected to increase the risk of neural tube defects. The presence of both trisomy 21 and postclosure NTD in the same child supports the need for an extended periconceptional period of maternal folate supplementation to achieve greater preventive effects for both NTD and trisomy 21.

Drug compliance among hypertensive patients in Kassala, eastern Sudan

A cross-sectional study of hypertensive patients was conducted and drug compliance was estimated. Factors associated with compliance, status of blood pressure control and occurrence of complications were assessed. Compliance was 59.6% as measured with the pill count method. We found 92% of compliant patients had controlled blood pressure in comparison with 18% of non-compliant patients, and 30.1% of the compliant patients had complications in comparison with 46.3% of the non-compliant patients. While the compliance rate was reasonable, 36.8% of patients were non-compliant because they could not afford to buy antihypertensive drugs. Inability to buy drugs was negatively and significantly associated with compliance. These patients experienced uncontrolled blood pressure and other complications.

A characteristic continuous wave Doppler signal in cor triatriatum?

Continuous wave Doppler recordings of the turbulent jet through the restrictive orifice of a left atrial partition in a patient with corrected transposition of the great arteries and cor triatriatum showed alternate bands of high intensity diastolic and low intensity systolic signals with preservation of the normal configuration of the diastolic E and A peaks. It is thought that Doppler studies in cor triatriatum will provide useful complementary haemodynamic information in the echocardiographic diagnosis of this anomaly.

A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation. The involuntary action of the external anal sphincter: histologic study

The histologic changes in the external anal sphincter after internal anal sphincter excision were studied in 20 dogs. An external sphincter biopsy was taken before internal sphincterectomy and 2 weeks and monthly thereafter for 10 months. The excised material was studied microscopically after being stained with hematoxylin and eosin, Verhoeff-van Gieson and succinic dehydrogenase. 70% of external sphincter specimens before internal sphincter excision showed smooth muscle fibers scattered between the striated fibers. These smooth fibers could be responsible for the resting tone of the external sphincter. After internal sphincter excision, characteristic histologic changes could be identified in the external sphincter. From the 2nd week to the 5th month after excision, the external sphincter showed degenerative and hypertrophic changes. From the 6th to the 10th month, there were regeneration of the striated muscle fibers and increase in the number of smooth fibers so that by the 10th month a 'compound' muscle of striated and smooth fibers was identified. Two theories were put forward to explain the smooth fiber preponderance in the external sphincter after internal sphincter excision: mutant and replacement theories. The increased nonstriated element in the external sphincter seems to be a structural-functional adaptation so that the external sphincter takes on the involuntary function of the excised muscle.