Growth responses of Escherichia coli and Myxococcus xanthus on agar gel substrates with different levels of stiffness

Bacteria colonize surfaces responding to the physicochemical properties of substrates. A systematic study was carried out with growing single bacterial colonies on the surface of agar media to decipher the interaction between bacterial growth and substrate stiffness. We investigated the growth kinetics of wild-type Escherichia coli, non-motile E. coli, and Myxococcus xanthus, cultured on semi-solid agar substrates containing different amounts of nutrient and agar. We found that substrate stiffness, which was controlled by agar concentration, modulates the growth of motile bacteria, such as wild-type E. coli and M. xanthus, independently of the nutrient level, but does not affect the growth response of non-motile E. coli. Interestingly, growth of M. xanthus moving with type IV pili correlates negatively with the substrate stiffness in contrast to wild-type E. coli propelled by flagella. The present study demonstrates that the type of surface motility is a key  determinant of the growth response of bacteria to substrate stiffness, and has potential application to the design of surfaces that prevent or promote biofilm formation.Key words: Bacterial colonization, substrate stiffness, surface motility, swarming, Escherichia coli, Myxococcus xanthus

Severe recurrent nocturnal hypoglycemia during chemotherapy with 6-mercaptopurine in a child with acute lymphoblastic leukemia

Various endocrine dysfunctions occur during chemotherapy, including hypoglycemia. However, reports of hypoglycemia associated with 6-mercaptopurine (6-MP) are rare. Herein, we report an 8-year-old boy with severe symptomatic hypoglycemia likely due to 6-MP during chemotherapy. He had been diagnosed with acute lymphoblastic leukemia 3 years previously and was in the maintenance chemotherapy period. Treatment included oral dexamethasone, methotrexate, and 6-MP, of which only 6-MP was administered daily. Hypoglycemic symptoms appeared mainly at dawn, and his serum glucose dropped to a minimum of 37 mg/dL. Laboratory findings showed nothing specific other than increased serum cortisol, free fatty acids, ketone, alanine aminotransferase, and aspartate aminotransferase. Under the hypothesis of hypoglycemia due to chemotherapy drugs, we changed the time of 6-MP from evening to morning and recommended him to ingest carbohydrate-rich foods before bedtime. Hypoglycemia improved dramatically, and there was no further episode during the remaining maintenance chemotherapy period. To the best of our knowledge, this is the first report of this type of hypoglycemia occurring in an Asian child including Korean

Clinical characteristics and treatment modalities of vulvovaginal atrophy in genitourinary syndrome of menopause

Background: Genitourinary syndrome of menopause (GSM) causes symptoms such as vaginal dryness, dysuria, repetitive urinary tract infection and urinary urgency may affect daily activities, sexual relationships, and overall quality of life. The aim of the study was to provide the clinical characteristics of VVA patients in South Korea and the effectiveness as well as complications of the currently used low dose estrogen vaginal suppository.Methods: 52 women who has visited the outpatient gynecology clinic of the National Health Insurance Service Ilsan Hospital from January 2018 to December 2019 were recruited as study subjects. For the analysis of the clinical characteristics, subjective symptoms described by the patient’s own words such as vaginal dryness, pain, dysuria, dyspareunia, or no symptoms at all were included. Objective signs such as thinning of vaginal rugae, mucosal dryness, and mucosal fragility and the presence of petechiae were recorded.Results: Vaginal dryness was the most common complaint (92.3%). Thinning of the vaginal rugae was the most commonly noted objective sign (73.1%). Of the 52 subjects, 31 (59.6%) refrained from using the low dose estrogen vaginal suppository. The most common reason for not being able to use the suppository was the inability to insert the suppository (32.3%).Conclusions: Although patient-reported symptoms and clinical objectivity through physical examination are two components in diagnosing VVA, further study is warranted for a more objective and discriminatory diagnosis criteria for VVA. As the only available treatment modality was low dose vaginal estrogen suppository, comparison with other treatment modalities were not available

Reduction formulae from the factorization Theorem of Littlewood-Richardson polynomials by King, Tollu and Toumazet

The factorization theorem by King, Tollu and Toumazet gives four different reduction formulae of Littlewood-Richardson coefficients. One of them is the classical reduction formula of the first type while others are new. Moreover, the classical reduction formula of the second type is not a special case of KTT theorem. We give combinatorial proofs of reduction formulae in terms of tableaux or hives. The proofs for the cases $r=1, 2, n-2$ in terms of tableaux and the proof for the classical reduction formula of the second type in terms of hives are new

Alpha-tocopherol exerts protective function against the mucotoxicity of particulate matter in amphibian and human goblet cells

Exposure to particulate matter (PM) in ambient air is known to increase the risk of cardiovascular disorders and mortality. The cytotoxicity of PM is mainly due to the abnormal increase of reactive oxygen species (ROS), which damage cellular components such as DNA, RNA, and proteins. The correlation between PM exposure and human disorders, including mortality, is based on long-term exposure. In this study we have investigated acute responses of mucus-secreting goblet cells upon exposure to PM derived from a heavy diesel engine. To this end, we employed the mucociliary epithelium of amphibian embryos and human Calu-3 cells to examine PM mucotoxicity. Our data suggest that acute exposure to PM significantly impairs mucus secretion and results in the accumulation of mucus vesicles in the cytoplasm of goblet cells. RNA-seq analysis revealed that acute responses to PM exposure significantly altered gene expression patterns; however, known regulators of mucus production and the secretory pathway were not significantly altered. Interestingly, pretreatment with alpha-tocopherol nearly recovered the hyposecretion of mucus from both amphibian and human goblet cells. We believe this study demonstrates the mucotoxicity of PM and the protective function of alpha-tocopherol on mucotoxicity caused by acute PM exposure from heavy diesel engines