The roles of phospholipid biosynthesis in Candida albicans virulence

Candida albicans is a major human fungal pathogen. A primary goal in studying C. albicans virulence is actually to find the ways to undermine it and prevent disease. The best drug targets are proteins or molecules that are not conserved in humans. For most antimicrobials against bacteria, fungi, or protozoans, the targets are not virulence factors, but rather enzymes that are important for basic growth or survival. It is not imperative that the target be required in all growth conditions, but rather just in the host. An area of research that has shown promising potential for the discovery of new drug targets in several microbal pathogens is in phospholipid biosynthesis. In this dissertation, there are three projects that revolve around studying proteins that may be potential drug targets for C. albicans. 1) inositol biosynthesis was examined.It has been shown in the pathogens Mycobacterium tuberculosis and Trypanosoma brucei that de novo inositol biosynthesis is required for virulence or growth. Therefore, the enzyme required for de novo inositol synthesis was examined for a role in virulence. 2) The phosphatidylserine (PS) synthase gene (CHO1) of S. cerevisiae is conserved in other fungi, and is not conserved in humans. Given that PS is an abundant phospholipid in yeasts, it was hypothesized that it would be important for virulence in the host. 3) Fungi carry homologs of a fungal-specific transcription factor, called Opi1p, that has been shown to be involved in regulating filamentous growth and phospholipid biosynthesis in S. cerevisiae. Its homolog was examined in C. albicans to determine if it regulated these phenotypes in this pathogen because filamentous growth is an important virulence factor.If the CaOpi1p protein were essential for filamentous growth then it might be good drug target as it is not conserved in humans. All three of these projects revolve around phospholipid biosynthesis in C. albicans and each has revealed interesting and sometime surprising aspects of the biology and virulence of this fungus

Recent Outbreak of Dengue in Taiwan

In 1987 a dengue outbreak occurred in southern Taiwan, and it persisted throughout the year 1988. Although some cases were reported yearly since then it did not constitute an epidemic as severe as that of 1988. During the period from November 1987 to 30 June 1993, a total of 5,168 serologically or virologically confirmed cases was detected. Of all the cases, 5,085 were considered locally infected, and 83 imported. The proportions of indigenous cases to imported cases were 527 to unknown in 1987, 4,389 to unknown in 1988, 16 to 19 in 1989, 0 to 10 in 1990, 149 to 26 in 1991, 4 to 19 in 1992, and 0 to 9 in 1993. The sources of the imported cases were Thailand (54 cases=65.1%), Philippines (11=13.3%), Singapore (8=9.6%), Indonesia (5=6%), Malaysia (2=2.4%), Vietnam (1=1.2%), India (1=1.2%) and Sri Lanka (1=1.2%). The dengue viruses were isolated both from mosquitoes and humans. Nine D-1 virus isolates were obtained from female mosquitoes of Aedes aegypti among the nine species of mosquitoes collected in houses in 1987 and 1988. The virus isolates from humans were 298 D-1 and 5 D-2 in 1987, 3,534 D-1, 3 D-4 and 1 D-3 in 1988, 5 D-1, 2 D-2 and 1 D-4 in 1989, 1 D-1 and 1 D-2 in 1990, 16 D-1 and 4 D-3 in 1991, and 2 D-1 and 2 D-3 in 1992

Relationship between Obesity-related Hormone Peptides and Quality of Life in Obese Women among Different Traditional Chinese Medicine Syndrome Groups

AbstractThe aim of this study was to explore the relationship between obesity-related hormone peptides and quality of life in obese women among different traditional Chinese medicine (TCM) syndrome groups (證型 zhèng xíng). 260 obese women met with age between 20 and 65years old and body mass index (BMI) ≧ 27kg/m2, were recruited. The participants filled out a questionnaire on obese TCM syndrome groups, which was designed by professional TCM doctors, and two questionnaires on quality of life (QOL), WHOQOL-BREF Taiwan version and MOS Short Form-12 (SF-12). Data of biochemical characteristics and obesity-related hormone peptides were collected at the same time. According to the responses provided, the obese subjects were classified into spleen deficiency with dampness encumbrance syndrome (脾虛濕阻證 pí xū shī zǔ zhèng; SDD), stomach heat with dampness encumbrance syndrome (胃熱濕阻證 wèi rè shī zǔ zhèng; SHD), liver depression and qi stagnation syndrome (肝鬱氣滯證 gān yù qì zhì zhèng; LDQ), dual spleen-kidney deficiency syndrome (脾腎兩虛證 pí shèn liǎng xū zhèng; SKD), yin deficiency with internal heat syndrome (陰虛內熱證 yīn xū nèi rè zhèng; YDI) and a control group. For physical conditions, SDD group had significantly higher means in weight and BMI compared with the control group. The insulin and leptin levels in SHD group were significantly higher than those in the control group. The LDQ group showed marked decrease in mental condition scores compared with the control group. This study found that obese women in the SDD group were fatter than those in the control group. SHD group might have greater influence on the regulation of obesity-related hormone peptides. The LDQ group had poor QOL than the control group. Analysis of TCM syndrome groups among obese women merits further investigation

Inhibition of Anchorage-Independent Proliferation and G0/G1 Cell-Cycle Regulation in Human Colorectal Carcinoma Cells by 4,7-Dimethoxy-5-Methyl-l,3-Benzodioxole Isolated from the Fruiting Body of Antrodia camphorate

In this study, 4,7-dimethoxy-5-methyl-l,3-benzodioxole (SY-1) was isolated from three different sources of dried fruiting bodies of Antrodia camphorate (AC). AC is a medicinal mushroom that grows on the inner heartwood wall of Cinnamomum kanehirai Hay (Lauraceae), an endemic species that is used in Chinese medicine for its anti-tumor and immunomodulatory properties. In this study, we demonstrated that SY-1 profoundly decreased the proliferation of human colon cancer cells (COLO 205) through G0/G1 cell-cycle arrest (50–150 μM) and induction of apoptosis (>150 μM). Cell-cycle arrest induced by SY-1 was associated with a significant increase in levels of p53, p21/Cip1 and p27/Kip1, and a decrease in cyclins D1, D3 and A. In contrast, SY-1 treatment did not induce significant changes in G0/G1 phase cell-cycle regulatory proteins in normal human colonic epithelial cells (FHC). The cells were cultured in soft agar to evaluate anchorage-independent colony formation, and we found that the number of transformed colonies was significantly reduced in the SY-1-treated COLO 205 cells. These findings demonstrate for the first time that SY-1 inhibits human colon cancer cell proliferation through inhibition of cell growth and anchorage-independent colony formation in soft agar. However, the detailed mechanisms of these processes remain unclear and will require further investigation

Overproduction of Phospholipids by the Kennedy Pathway Leads to Hypervirulence in Candida albicans

Candida albicans is an opportunistic human fungal pathogen that causes life-threatening systemic infections, as well as oral mucosal infections. Phospholipids are crucial for pathogenesis in C. albicans, as disruption of phosphatidylserine (PS) and phosphatidylethanolamine (PE) biosynthesis within the cytidine diphosphate diacylglycerol (CDP-DAG) pathway causes avirulence in a mouse model of systemic infection. The synthesis of PE by this pathway plays a crucial role in virulence, but it was unknown if downstream conversion of PE to phosphatidylcholine (PC) is required for pathogenicity. Therefore, the enzymes responsible for methylating PE to PC, Pem1 and Pem2, were disrupted. The resulting pem1Δ/Δ pem2Δ/Δ mutant was not less virulent in mice, but rather hypervirulent. Since the pem1Δ/Δ pem2Δ/Δ mutant accumulated PE, this led to the hypothesis that increased PE synthesis increases virulence. To test this, the alternative Kennedy pathway for PE/PC synthesis was exploited. This pathway makes PE and PC from exogenous ethanolamine and choline, respectively, using three enzymatic steps. In contrast to Saccharomyces cerevisiae, C. albicans was found to use one enzyme, Ept1, for the final enzymatic step (ethanolamine/cholinephosphotransferase) that generates both PE and PC. EPT1 was overexpressed, which resulted in increases in both PE and PC synthesis. Moreover, the EPT1 overexpression strain is hypervirulent in mice and causes them to succumb to system infection more rapidly than wild-type. In contrast, disruption of EPT1 causes loss of PE and PC synthesis by the Kennedy pathway, and decreased kidney fungal burden during the mouse systemic infection model, indicating a mild loss of virulence. In addition, the ept1Δ/Δ mutant exhibits decreased cytotoxicity against oral epithelial cells in vitro, whereas the EPT1 overexpression strain exhibits increased cytotoxicity. Taken altogether, our data indicate that mutations that result in increased PE synthesis cause greater virulence and mutations that decrease PE synthesis attenuate virulence

Poly (ADP-ribose) polymerase plays an important role in intermittent hypoxia-induced cell death in rat cerebellar granule cells

<p>Abstract</p> <p>Background</p> <p>Episodic cessation of airflow during sleep in patients with sleep apnea syndrome results in intermittent hypoxia (IH). Our aim was to investigate the effects of IH on cerebellar granule cells and to identify the mechanism of IH-induced cell death.</p> <p>Methods</p> <p>Cerebellar granule cells were freshly prepared from neonatal Sprague-Dawley rats. IH was created by culturing the cerebellar granule cells in the incubators with oscillating O₂concentration at 20% and 5% every 30 min for 1-4 days. The results of this study are based on image analysis using a confocal microscope and associated software. Cellular oxidative stress increased with increase in IH. In addition, the occurrence of cell death (apoptosis and necrosis) increased as the duration of IH increased, but decreased in the presence of an iron chelator (phenanthroline) or poly (ADP-ribose) polymerase (PARP) inhibitors [3-aminobenzamide (3-AB) and DPQ]. The fluorescence of caspase-3 remained the same regardless of the duration of IH, and Western blots did not detect activation of caspase-3. However, IH increased the ratio of apoptosis-inducing factor (AIF) translocation to the nucleus, while PARP inhibitors (3-AB) reduced this ratio.</p> <p>Results</p> <p>According to our findings, IH increased oxidative stress and subsequently leading to cell death. This effect was at least partially mediated by PARP activation, resulting in ATP depletion, calpain activation leading to AIF translocation to the nucleus.</p> <p>Conclusions</p> <p>We suggest that IH induces cell death in rat primary cerebellar granule cells by stimulating oxidative stress PARP-mediated calpain and AIF activation.</p

Vitamin D level regulates serum lipids discrepantly in adults with and without dyslipidemia

Vitamin D deficiency is associated with hyperlipidemia, but it r emains unclear whether vitamin D supplementation reduces serum lipid levels. The aims of this study were to investigate the associations between increased serum 25-hydroxyvitamin D (25(OH)D) concentrations and lipid levels and identify the characteristics of people with or without lipid reduction associated with increased 25(OH)D levels. The medical records of 118 individuals (53 men; mean age, 54.4 ± 10.6 years) whose serum 25(OH)D levels increased between 2 consecutive measurements were retrospectively reviewed. People with increased 25(OH)D levels (from 22.7 (17.6–29.2) to 32.1 (25.6–36.8) mg/dL; P < 0.01) had a significant reduction in serum levels of triglycerides (TG s) (from 111.0 (80–164) to 104.5 (73–142) mg/dL; P < 0.01) and total cholesterol (TC) (from 187.5 (155–213) to 181.0 (150–210) mg/dL; P < 0.05). The individuals who responded to vitamin D (≥10% reduction in TG or TC levels) exhibited significantly higher baseline TG a nd TC levels than those who did not. Only patients with hyperlipidemia (not those without hyperlipidemia) at baseline exhibited significantly reduced TG and TC levels at fol low-up. However, increasing serum 25(OH)D concentrations were significantly correlated with decreasing lipid levels in individuals with baseline 25(OH)D levels less than 30 ng/mL and in individuals aged 50–65 years (not in patients younger than 50 years or older than 65 years). In conclusion, increasing serum 25(OH)D concentrations may be potentially helpful for the treatment of hyperlipidemia in people with vitamin D deficiency

Analyzing 13 Years of Cetacean Strandings: Multiple Stressors to Cetaceans in Taiwanese Waters and Their Implications for Conservation and Future Research

This study summarizes the postmortem investigations of 73 cetaceans stranded on the coast of Taiwan between 2001 and 2013, including 51 Delphinidae, 17 Kogiidae, 3 Ziphiidae, 1 Physeteridae, and 1 Balaenopteridae. Of these, eight (11%) were categorized into direct human-related strandings, including fisheries interaction (bycatch), vessel collision and other anthropogenic-related pathology. Gastrointestinal foreign bodies were found in eight individuals (11%). Most of the bacteria isolated from stranded dolphins were zoonotic pathogens including extended-spectrum β-lactamases Escherichia coli, which indicates waste pollution from land. Severe parasite infestation was found in 36 of the cases (49%), which suggests that the immune function could be compromised. Thirty-eight cases (52%) were diagnosed with myocardial patchy fibrosis or dilated cardiomyopathy. The evidence shown here indicates that cetaceans around Taiwanese waters may suffer from multiple stressors. This study provides baseline data for the health assessment of cetacean populations in Taiwan, which may ultimately provide recommendations for future cetacean conservation and research throughout the western Pacific