Stretch stress propels glutamine dependency and glycolysis in optic nerve head astrocytes.

Glaucoma is an optic neuropathy that leads to irreversible blindness, the most common subtype of which is typified by a chronic increase in intraocular pressure that promotes a stretch injury to the optic nerve head. In rodents, the predominant glial cell in this region is the optic nerve head astrocyte that provides axons with metabolic support, likely by releasing lactate produced through astrocytic glycolysis. Our primary hypothesis is that stretching of the optic nerve head astrocytes alters their metabolic activity, thereby advancing glaucoma-associated degeneration by compromising the metabolic support that the astrocytes provide to the axons in the optic nerve head. Metabolic changes in optic nerve head astrocytes were investigated by subjecting them to 24 h of 12% biaxial stretch at 1 Hz then measuring the cells' bioenergetics using a Seahorse XFe24 Analyzer. We observed significant glycolytic and respiratory activity differences between control and stretched cells, including greater extracellular acidification and lower ATP-linked respiration, yet higher maximal respiration and spare capacity in stretched optic nerve head astrocytes. We also determined that both control and stretched optic nerve head astrocytes displayed a dependency for glutamine over pyruvate or long-chain fatty acids for fuel. The increased use of glycolysis as indicated by the extracellular acidification rate, concomitant with a dependency on glutamine, suggests the need to replenish NAD + for continued glycolysis and provision of carbon for TCA cycle intermediates. Stretch alters optic nerve astrocyte bioenergetics to support an increased demand for internal and external energy.

Hot Weather and Suicide Deaths among Older Adults in Hong Kong, 1976-2014: A Retrospective Study.

Findings of the association between hot weather and suicide in a subtropical city such as Hong Kong are inconsistent. This study aimed to revisit the association by identifying meteorological risk factors for older-adult suicides in Hong Kong using a time-series approach. A retrospective study was conducted on older-adult (aged ≥65) suicide deaths in Hong Kong from 1976 to 2014. Suicides were classified into those involving violent methods and those involving nonviolent methods. Meteorological data, including ambient temperature, were retrieved. Transfer function time-series models were fitted. In total, 7314 older-adult suicide deaths involving violent methods and 630 involving nonviolent methods were recorded. For violent-method suicides, a monthly average daily minimum ambient temperature was determined to best predict the monthly rate, and a daily maximum ambient temperature of 30.3 °C was considered the threshold. For suicide deaths involving nonviolent methods, the number of days in a month for which the daily maximum ambient temperature exceeded 32.7 °C could best predict the monthly rate. Higher ambient temperature was associated with more older-adult suicide deaths, both from violent and nonviolent methods. Weather-focused preventive measures for older-adult suicides are necessary, such as the provision of more public air-conditioned areas where older adults can shelter from extreme hot weather.

Glutaminase Activity of L-Asparaginase Contributes to Durable Preclinical Activity against Acute Lymphoblastic Leukemia.

We and others have reported that the anticancer activity of L-asparaginase (ASNase) against asparagine synthetase (ASNS)-positive cell types requires ASNase glutaminase activity, whereas anticancer activity against ASNS-negative cell types does not. Here, we attempted to disentangle the relationship between asparagine metabolism, glutamine metabolism, and downstream pathways that modulate cell viability by testing the hypothesis that ASNase anticancer activity is based on asparagine depletion rather than glutamine depletion per se. We tested ASNase wild-type (ASNaseWT) and its glutaminase-deficient Q59L mutant (ASNaseQ59L) and found that ASNase glutaminase activity contributed to durable anticancer activity against xenografts of the ASNS-negative Sup-B15 leukemia cell line in NOD/SCID gamma mice, whereas asparaginase activity alone yielded a mere growth delay. Our findings suggest that ASNase glutaminase activity is necessary for durable, single-agent anticancer activity in vivo, even against ASNS-negative cancer types.

Self-management of gestational diabetes among Chinese migrants: A qualitative study.

BACKGROUND: Gestational diabetes mellitus is one of the most common complications of pregnancy. Women with Gestational diabetes are at increased risk of serious health outcomes, such as pre-eclampsia, obstructed labor, and the development of Type 2 diabetes later in life. Chinese migrants, the third largest cultural group in Australia, are more likely to develop Gestational diabetes than Australian-born women. However, to date, Gestational diabetes self-management has not been investigated in this population. AIM: To explore the understanding and self-management experiences of Gestational diabetes among Chinese migrants. METHODS: Data were collected through individual semi-structured face-to-face interviews. Participants were recruited from the antenatal clinic at the Royal Prince Alfred Hospital. Interviews were audio-recorded, transcribed verbatim and thematically analyzed. FINDINGS: Although the majority of participants demonstrated a good understanding of Gestational diabetes, some did not understand the principles behind healthcare advice and faced challenges in self-management. Confusion about self-monitoring of blood glucose and fear of insulin were also evident. Participants relied on both formal and informal sources of information. Some had difficulty obtaining adequate support. Cultural influences on self-management included meeting family needs, Chinese diet and use of Chinese medicines. CONCLUSION: To assist Chinese women with Gestational diabetes to better self-manage their condition, there is a need for clinicians to: (1) provide more effective diabetes education to ensure clear understanding of self-management principles; (2) actively elicit and respond to women's confusion and concerns; (3) provide women with adequate practical support; and (4) develop greater cultural awareness.

Multiplexed parallel reaction monitoring targeting histone modifications on the QExactive mass spectrometer.

Histone acetylation and methylation play an important role in the regulation of gene expression. Irregular patterns of histone global acetylation and methylation have frequently been seen in various diseases. Quantitative analysis of these patterns is of high value for the evaluation of disease development and of outcomes from therapeutic treatment. Targeting histone acetylation and methylation by selected reaction monitoring (SRM) is one of the current quantitative methods. Here, we reported the use of the multiplexed parallel reaction monitoring (PRM) method on the QExactive mass spectrometer to target previously known lysine acetylation and methylation sites of histone H3 and H4 for the purpose of establishing precursor-product pairs for SRM. 55 modified peptides among which 29 were H3 K27/K36 modified peptides were detected from 24 targeted precursor ions included in the inclusion list. The identification was carried out directly from the trypsin digests of core histones that were separated without derivatization on a homemade capillary column packed with Waters YMC ODS-AQ reversed phase materials. Besides documenting the higher-energy c-trap dissociation (HCD) MS(2) spectra of previously known histone H3/H4 acetylated and methylated tryptic peptides, we identified novel H3 K18 methylation, H3 K27 monomethyl/acetyl duel modifications, H2B K23 acetylation, and H4 K20 acetylation in mammalian histones. The information gained from these experiments sets the foundation for quantification of histone modifications by targeted mass spectrometry methods directly from core histone samples.

Correlation spectroscopy of minor fluorescent species: signal purification and distribution analysis.

We are performing experiments that use fluorescence resonance energy transfer (FRET) and fluorescence correlation spectroscopy (FCS) to monitor the movement of an individual donor-labeled sliding clamp protein molecule along acceptor-labeled DNA. In addition to the FRET signal sought from the sliding clamp-DNA complexes, the detection channel for FRET contains undesirable signal from free sliding clamp and free DNA. When multiple fluorescent species contribute to a correlation signal, it is difficult or impossible to distinguish between contributions from individual species. As a remedy, we introduce "purified FCS", which uses single molecule burst analysis to select a species of interest and extract the correlation signal for further analysis. We show that by expanding the correlation region around a burst, the correlated signal is retained and the functional forms of FCS fitting equations remain valid. We demonstrate the use of purified FCS in experiments with DNA sliding clamps. We also introduce "single-molecule FCS", which obtains diffusion time estimates for each burst using expanded correlation regions. By monitoring the detachment of weakly-bound 30-mer DNA oligomers from a single-stranded DNA plasmid, we show that single-molecule FCS can distinguish between bursts from species that differ by a factor of 5 in diffusion constant.

Low-dose irradiation alters the transcript profiles of human lymphoblastoid cells including genes associated with cytogenetic radioadaptive response.

Low-dose ionizing radiation alters the gene expression profiles of mammalian cells, yet there is little understanding of the underlying cellular mechanisms responsible for these changes or of their consequences for genomic stability. We investigated the cytogenetic adaptive response of human lymphoblastoid cell lines exposed to 5 cGy (priming dose) followed by 2 Gy (challenge dose) compared to cells that received a single 2-Gy dose to (a) determine how the priming dose influences subsequent gene transcript expression in reproducibly adapting and non-adapting cell lines, and (b) identify gene transcripts that are associated with reductions in the magnitude of chromosomal damage after the challenge dose. The transcript profiles were evaluated using oligonucleotide arrays and RNA obtained 4 h after the challenge dose. A set of 145 genes (false discovery rate = 5%) with transcripts that were affected by the 5-cGy priming dose fell into two categories: (a) a set of common genes that were similarly modulated by the 5-cGy priming dose irrespective of whether the cells subsequently adapted or not and (b) genes with differential transcription in accordance with the cell lines that showed either adaptive or non-adaptive outcomes. The common priming-dose response genes showed up-regulation for protein synthesis genes and down-regulation of metabolic and signal transduction genes (>10-fold differences). The genes associated with subsequent adaptive and non-adaptive outcomes involved DNA repair, stress response, cell cycle control and apoptosis. Our findings support the importance of TP53-related functions in the control of the low-dose cytogenetic radioadaptive response and suggest that certain low-dose-induced alterations in cellular functions are predictive for the risk of subsequent genomic damage.