Genetic analysis of a family affected by congenital myasthenic syndrome due to a Novel mutation in the SLC5A7 gene.

BACKGROUND: Mutations in the SLC5A7 gene cause congenital myasthenia, a rare genetic disorder. Mutation points in the SLC5A7 gene differ among individuals and encompass various genetic variations; however, exon deletion variants have yet to be reported in related cases. This study aims to explore the clinical phenotype and genetic traits of a patient with congenital myasthenic syndrome due to SLC5A7 gene variation and those of their family members. CASE PRESENTATION: We describe a case of a Chinese male with congenital myasthenic syndrome presenting fluctuating limb weakness. Genetic testing revealed a heterozygous deletion mutation spanning exons 1-9 in the SLC5A7 gene. QPCR confirmed a deletion in exon 9 of the SLC5A7 gene in the patient's mother and brother. Clinical symptoms of myasthenia improved following treatment with pyridostigmine. CONCLUSION: Exons 1, 5, and 9 of the SLC5A7 gene encode the choline transporter's transmembrane region. Mutations in these exons can impact the stability and plasma membrane levels of the choline transporter. Thus, a heterozygous deletion in exons 1-9 of the SLC5A7 gene could be the pathogenic cause for this patient. In patients exhibiting fluctuating weakness, positive RNS, and seronegativity for myasthenia gravis antibodies, a detailed family history should be considered, and enhanced genetic testing is recommended to determine the cause.

Total arsenic and speciation analysis of saliva and urine samples from individuals living in a chronic arsenicosis area in China.

BACKGROUND: It is generally acknowledged that the determination of harmful chemical compounds excreted into saliva is useful for assessing their exposure levels. The aim of the present study was to compare the total arsenic and its species in saliva and urine samples collected from the people residing in an arsenic-contaminated area of China and to further verify the feasibility of using salivary arsenic as a new biomarker of arsenic exposure. METHODS: Total arsenic and speciation analyses in urine and saliva samples among 70 residents exposed to arsenic from drinking water in Shanxi, China were carried out by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP/MS). RESULTS: The result showed that, total arsenic concentration in saliva was relatively lower than in urine samples, but it existed a strong positive correlation with total urinary arsenic, drinking water arsenic and different skin lesions. For arsenic metabolism analyses, AsIII, AsV, MMA, and DMA were detected in all of the urine samples with the dominating species of DMA (73.2%). Different with urinary arsenic species, most arsenic species in saliva were not methylated. The major species in saliva was iAs (AsIII + AsV, 76.18%), followed by DMA (13.08%) and MMA (9.13%). And the primary methylation index (PMI), second methylation index (SMI) and proportion of the four different species (AsIII, AsV, MMA, and DMA) in saliva showed no significant positive relationship with that of in urine. CONCLUSIONS: These findings indicated saliva may be used as a useful tool for biological monitoring of total arsenic exposure in the crowd rather than an efficient tool for assessing arsenic metabolism in human body after exposed to arsenic.

Hypermethylation of the Keap1 gene inactivates its function, promotes Nrf2 nuclear accumulation, and is involved in arsenite-induced human keratinocyte transformation.

It is well known that long-term exposure to arsenite leads to human skin cancer, but the underlying mechanisms of carcinogenesis remain obscure. The transcription factor Nrf2-mediated antioxidant response represents a critical cellular defense mechanism; however, emerging data suggest that constitutive activation of Nrf2 is associated with cancer development and chemotherapy resistance. The reasons Nrf2 continuously accumulates in cancer cells remain to be fully understood. By establishing transformed human keratinocyte cells via chronic arsenite treatment, we observed a continuous reduction in reactive oxygen species levels and enhanced levels of Nrf2 and its target antioxidant enzymes in the later stage of arsenite-induced cell transformation. We also revealed that hypermethylation of the Keap1 gene promoter region induced by DNA methyltransferase-3 leading to inactivation of its function was responsible for constitutive activation of Nrf2 and its target enzymes. To validate these observations, the expression of Keap1 protein was restored in arsenite-transformed cells by treatment with a DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine (5-Aza-dC), and protein levels of Nrf2 and colony formation were then determined after these treatments. Results showed that enhancement of Keap1 expression by 5-Aza-dC significantly reduced Nrf2 and its target antioxidant enzyme levels, and that in turn suppressed cell proliferation and colony formation of the transformed cells. Taken together, the present study strongly suggests that loss of Keap1 function by hypermethylation of its promoter region leading to Nrf2 nuclear accumulation appears to play a role in arsenite-induced human keratinocyte transformation.

[Dynamic changes of ROS, MDA and SOD during arsenic-induced neoplastic transformation in human keratinocytes].

OBJECTIVE: To investigate the level of ROS, MDA and SOD in different stages of arsenic-induced neoplastic transformation in human keratinocytes. METHODS: HaCaT human immortalized keratinocytes were continuously exposed to 1.0 µmol/L arsenite for 35 passages. The secretion of active MMP-9, the proliferation rate and doubling time nd colony formation assay in soft agar colony were used to identify the malignant phenotype of the arsenite-exposed HaCaT cells. Then flow cytometry was used to detect the levels of ROS, and the level of MDA and SOD were tested by biochemical method at different passages of arsenite exposure in HaCaT cells. RESULTS: A marked increase in the secretion of active MMP-9 in the arsenic-treated (1.0 µmol/L NaAsO2) cells was observed in comparison to the passage-matched untreated control (0.0 µmol/L NaAsO2) cells at 28 and 35 passages. And compared with 0.0 µmol/L NaAsO2 group, the proliferation rate and doubling time in 1.0 µmol/L NaAsO2 group was much faster at 21 ((64.37 ± 15.92) h) and 28 ((64.04 ± 12.84) h) passages with a significant statistical difference at passage 35 ((54.00 ± 2.35 ) h) (P < 0.05). Furthermore, the long-term arsenite-treated cells formed significantly higher colonies (107 ± 11 in passage 35) in soft agar than control cells (P < 0.05). No obvious regularity changes of ROS and MDA levels were found before 14 passages of arsenite exposure, except for passage 1. Surprisingly, after 14 passages, with the increased passages of exposure to arsenite, both the ROS and MDA levels decreased gradually, the ROS level at passage 35 was significant lower compared to passage 0 (P < 0.05). Conversely, after passage 21, the activity of SOD was obviously enhanced and reached the highest level at passage 35. CONCLUSION: Long-term exposure to low concentrations of inorganic arsenic-induced malignant transformation of HaCaT cells is accompanied by intracellular imbalance between oxidative-antioxidant, which increased expression of SOD and low levels of ROS found in the later-stage of arsenite-induced transformation.

Simultaneous analysis of anthocyanins and flavonols in petals of lotus (Nelumbo) cultivars by high-performance liquid chromatography-photodiode array detection/electrospray ionization mass spectrometry.

A fast and reliable HPLC method for the simultaneous separation of anthocyanins and flavonols in lotus petals was developed based on the study of four candidate solvent systems. Fifteen flavonoids were identified by high-performance liquid chromatography with photodiode array detection/mass spectrometry. Among them, two anthocyanins and nine flavonols were discovered in lotus petals for the first time. This work is valuable for both the hybrid breeding on lotus oriented to flower color and the utilization of lotus petals as functional food materials.