Arginine shortage induces replication stress and confers genotoxic resistance by inhibiting histone H4 translation and promoting PCNA ubiquitination

The arginine dependency of cancer cells creates metabolic vulnerability. In this study, we examine the impact of arginine availability on DNA replication and genotoxicity resistance. Using DNA combing assays, we find that limiting extracellular arginine results in the arrest of cancer cells at S phase and a slowing or stalling of DNA replication. The translation of new histone H4 is arginine dependent and influences DNA replication. Increased proliferating cell nuclear antigen (PCNA) occupancy and helicase-like transcription factor (HLTF)-catalyzed PCNA K63-linked polyubiquitination protect arginine-starved cells from DNA damage. Arginine-deprived cancer cells display tolerance to genotoxicity in a PCNA K63-linked polyubiquitination-dependent manner. Our findings highlight the crucial role of extracellular arginine in nutrient-regulated DNA replication and provide potential avenues for the development of cancer treatments.

Arginine shortage induces replication stress and confers genotoxic resistance by inhibiting histone H4 translation and promoting PCNA polyubiquitination

The unique arginine dependencies of cancer cell proliferation and survival creates metabolic vulnerability. Here, we investigate the impact of extracellular arginine availability on DNA replication and genotoxic resistance. Using DNA combing assays, we find that when extracellular arginine is limited, cancer cells are arrested at S-phase and DNA replication forks slow or stall instantly until arginine is re-supplied. The translation of new histone H4 is arginine-dependent and impacts DNA replication and the expression of newly synthesized histone H4 is reduced in the avascular nutrient-poor breast cancer xenograft tumor cores. Furthermore, we demonstrate that increased PCNA occupancy and HLTF-catalyzed PCNA K63-linked polyubiquitination protects arginine-starved cells from hydroxyurea-induced, DNA2-catalyzed nascent strand degradation. Finally, arginine-deprived cancer cells are tolerant to genotoxic insults in a PCNA K63-linked polyubiquitination-dependent manner. Together, these findings reveal that extracellular arginine is the "linchpin" for nutrient-regulated DNA replication. Such information could be leveraged to expand current modalities or design new drug targets against cancer.

Amino acid restriction induces a long non-coding RNA UBA6-AS1 to regulate GCN2-mediated integrated stress response in breast cancer

Oncogene activation, massive proliferation, and increased nutrient demands often result in nutrient and oxygen deprivation in solid tumors including breast cancer (BC), leading to the induction of oxidative stress and endoplasmic reticulum (ER) stress, and subsequently triggering integrated stress response (ISR). To elucidate the role of long non-coding RNAs (lncRNAs) in the ISR of BC, we performed transcriptome analyses and identified a lncRNA, UBA6-AS1, which was upregulated upon amino acid deprivation and ER stress. UBA6-AS1 was preferentially induced in triple-negative BC (TNBC) cells deprived of arginine or glutamine, two critical amino acids required for cancer cell growth, or treated with ER stress inducers. Mechanistically, UBA6-AS1 was regulated through the GCN2/eIF2α/ATF4 pathway, one of the major routes mediating ISR in amino acid sensing. In addition, both in vitro and in vivo assays indicated that UBA6-AS1 promoted TNBC cell survival when cells encountered metabolic stress, implicating a regulatory role of UBA6-AS1 in response to intratumoral metabolic stress during tumor progression. Moreover, PARP1 expression and activity were positively regulated by the GCN2/UBA6-AS1 axis upon amino acid deprivation. In conclusion, our data suggest that UBA6-AS1 is a novel lncRNA regulating ISR upon metabolic stress induction to promote TNBC cell survival. Furthermore, the GCN2-ATF4 axis is important for UBA6-AS1 induction to enhance PARP1 activity and could serve as a marker for the susceptibility of PARP inhibitors in TNBC.

Abstract 3724: BMAL1 rewires mitochondrial metabolism and promotes tumor progress of triple negative breast cancer during insulin resistance

Insulin resistance is a hallmark of metabolic diseases and negatively associated with breast cancer outcomes. While much work has dedicated to circadian dysregulation, metabolic diseases in breast cancer progression, the molecular mechanism connecting all these perspectives together has not yet established. To understand this underlying mechanism, we use in vitro and in vivo insulin-resistant triple-negative breast cancer (TNBC) models, illustrating that insulin resistance in TNBC reciprocally alters mitochondrial respiration and the expression of genes in the circadian rhythm pathway. Furthermore, genetic knockdown of BMAL1, an important circadian transcription factor, ablates key adaptations to insulin resistance, such as increased pyruvate flux, oxygen consumption, and lipid storage. Our in vivo study demonstrates that orthotopically transplanted E0771 mouse breast cancer cells with BMAL1 knocked down grow significantly faster than the parental counterpart in mice fed with the high-fat diet. This new understanding of BMAL1 expands our insights into circadian control of tumor metabolism and may lead to novel treatments for breast cancer.

Citation Format: Cassandra A. Ramos, Ching Ouyang, Yue Qi, Yiyin Chung, Chun-Ting Cheng, Mark A. LaBarge, Victoria L. Seewasldt, David K. Ann. BMAL1 rewires mitochondrial metabolism and promotes tumor progress of triple negative breast cancer during insulin resistance [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3724.

Abstract P1-05-10: lncRNA UBA6-AS1 participates in the integrated stress response of breast cancer

Breast cancer is the most prevalent malignant neoplasm among women worldwide and in Taiwan, and the incidence of breast cancer has been increasing over the past years. Accumulating studies has shown that multiple stress responses are activated in breast cancer. Oncogene activation, massive proliferation and increased nutrient demands often result in nutrient and oxygen deprivation, which triggers integrated stress response (ISR) in tumor cells. ISR dictates the cellular adaptive signaling in response to the intrinsic and extrinsic stresses, which lead to endoplasmic reticulum (ER) stress and cytosolic stress. Delineating the regulatory mechanisms of ISR may help us understand how cancer cells adapt and survive under stressed condition.

To elucidate the role of long non-coding RNAs (lncRNAs) in the ISR of breast cancer, we have performed a two-step human lncRNA RNA interference (RNAi) screening coupled with cell viability assays in a breast cancer cell line MDA-MB-231 under glucose deprivation to induce extrinsic metabolic stress. A novel lncRNA, UBA6-AS1, was identified to be upregulated to promote breast cancer cell death upon glucose deprivation. Besides of glucose deprivation, UBA6-AS1 was also induced by the deprivation of amino acids including glutamine and arginine in several breast cancer cell lines, suggesting that the upregulation of UBA6-AS1 was a universal metabolic stress event. We also found that UBA6-AS1 expression was increased upon the administration of ER stress inducers, tunicamycin (Tm) and thapsigargin (Tg) in breast cancer cells, implicating a potential role of UBA6-AS1 in harmonizing the nutrient and ER stresses. Moreover, after analyzing the genomic position and sequence of UBA6-AS1, activating transcription factor 4 (ATF4), a critical regulator in the ISR coordinating nutrient and ER stress signaling for controlling cell survival and stress adaption, has been predicted to be the regulator of UBA6-AS1 upon the induction of nutrient stress, further supporting the role of UBA6-AS1 participating in the ISR of breast cancer cells.

Depletion of UBA6-AS1 rendered breast cancer cells more resistant to nutrient deprivation, and the opposite results were observed when UBA6-AS1 was overexpressed, indicating that UBA6-AS1 may participate in the regulation of breast cancer cell survival under metabolic stress. To investigate the function of UBA6-AS1, RNA-sequencing (RNA-seq) was performed to profile gene expression in breast cancer cells overexpressing UBA6-AS1. The RNA-seq analysis revealed that the top 10 enriched biological processes were mostly related to apoptosis or programmed cell death in the UBA6-AS1 overexpressing cells, suggesting that the up-regulation of UBA6-AS1 may induce apoptosis in response to metabolic stress.

In the future, we will focus on the molecular mechanism of the regulation and function of UBA6-AS1 as well as its biological role and association with breast cancer progression.

Citation Format: Yi-Zhen Wu, Yi-Hsuan Chen, Chun-Ting Cheng, Kevin Chi, Tse-Chun Kuo, Hsing-Jien Kung, David Kong Ann, Ching-Ying Kuo. lncRNA UBA6-AS1 participates in the integrated stress response of breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-05-10.

Abstract P1-05-03: Phosphorylation of KAP1 Serine 473 regulates mitochondrial dynamics through miR-20b under metabolic stress in breast cancer

Cancer has been considered a metabolic disease in recent years. Compared to normal cells, cancer cells rewire metabolic pathways to sustain their outgrowth. While growing fast, cancer cells in the core region of a solid tumor encounter metabolic stress induced by hypoxia and insufficient nutrition, and mitochondrial dynamics has a profound effect on the survival of cancer cells. However, how mitochondrial dynamics affects cancer cell survival under metabolic stress has not been fully elucidated.

Krüppel-associated box-associated protein-1 (KAP1), also known as TRIM28, is a transcriptional co-regulator participating in multiple cellular physiological processes. The post-translational modifications of KAP1 play an essential role in regulating its function. We have previously demonstrated that KAP1 mRNA is highly expressed in concomitant with the upregulation of genes involving in glycolysis and oxidative phosphorylation in breast cancer. Furthermore, KAP1 is phosphorylated at Serine 473 (pS473) upon the induction of nutrient stresses via reactive oxygen species (ROS)-p38 MAPK signaling in breast cancer cells. The S473 phosphorylation of KAP1 reduces the expression of mitochondrial outer membrane protein mitofusin 2 (MFN2), which prevents the hyperfusion of mitochondria and the overproduction of ROS under nutrient deprivation. However, the mechanism of how KAP1 regulates the expression of MFN2 remains unclear.

We have engineered a KAP1-deficient MDA-MB-231 cell line and re-expressed KAP1 S473 wild-type (WT), S473A (phosphorylation-defective) or S473D (phosphorylation-mimic) mutants. By analyzing the mRNA expression profiles from these cell lines, several microRNAs (miRNAs) were shown to be upregulated in the KAP1 S473D-expressing cells, which implied that pS473-KAP1 may regulate MFN2 expression through miRNA.

Using several miRNA target prediction algorithms, miR-20b was predicted to target the 3’-untranslated region (UTR) of MFN2 mRNA, and the sequence of target site was conserved through evolution. By performing MFN2 3’UTR dual luciferase reporter assays, we have confirmed that MFN2 3’UTRwas targeted by miR-20b and regulated by the phosphorylation status at S473 of KAP1. Also, miR-20b expression was upregulated upon glucose deprivation and both MFN2 mRNA and protein levels declined in breast cancercells overexpressed with miR-20b mimics. In addition, KAP1 S473D, rather than S473A-expressing cells produced more miR-20b under glucose depletion condition and MFN2 expression levels were inversely correlated with miR-20b expression. Moreover, the analysis of The Cancer Genome Atlas (TCGA) breast tumor datasets indicated that there was higher miR-20b but lower MFN2 expression in advanced breast tumors compared with the primary tumors and normal tissues.

In conclusion, these results suggested that the induction of KAP1 S473 phosphorylation under nutrition deprivation inhibited MFN2 by upregulating miR-20b, which prevented mitochondrial hyperfusion and consequently benefited breast cancer cell survival in response to metabolic stress.

Citation Format: Yu-Shu Liu, Chun-Ting Cheng, Ching Ouyang, Ge-Jyun Liu, David Kong Ann, Ching-Ying Kuo. Phosphorylation of KAP1 Serine 473 regulates mitochondrial dynamics through miR-20b under metabolic stress in breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-05-03.

A Non-canonical Function of BMAL1 Metabolically Limits Obesity-Promoted Triple-Negative Breast Cancer

The epidemiological association between disrupted circadian rhythms and metabolic diseases is implicated in increased risk of human breast cancer and poor therapeutic outcomes. To define a metabolic phenotype and the underlying molecular mechanism, we applied chronic insulin treatment (CIT) to an in vitro model of triple-negative breast cancer to directly address how BMAL1, a key circadian transcription factor, regulates cancer cell respiration and governs tumor progression. At the cellular level, BMAL1 suppresses the flexibility of mitochondrial substrate usage and the pyruvate-dependent mitochondrial respiration induced by CIT. We established an animal model of diet-induced obesity/hyperinsulinemia and observed that BMAL1 functions as a tumor suppressor in obese, but not lean, mice. Downregulation of BMAL1 is associated with higher risk of metastasis in human breast tumors. In summary, loss of BMAL1 in tumors confers advantages to cancer cells in both intrinsic mitochondrial metabolism and extrinsic inflammatory tumor microenvironment during pre-diabetic obesity/hyperinsulinemia.

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Circadian regulator BMAL1 rewires metabolism in a chronic insulin-treated TNBC model

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Pyruvate links BMAL1 to mitochondrial bioenergetics

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BMAL1 suppresses tumor proliferation and metastasis in hyperinsulinemic obese mice

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BMAL1 influences tumor microenvironment in high-fat-diet-fed mice

Advanced nanotechnology: An arsenal to enhance immunotherapy in fighting cancer

Cancer remains a major disease process with considerable healthcare and socioeconomic impact worldwide. Unfortunately, standard treatments using chemotherapy often do not effectively control cancer progression or prevent relapse. Over the past decades, the development of targeted therapies has substantially improved outcomes. Recently, immunotherapy has emerged as a new alternative for more effective cancer treatment and may even bring hope of a cure. Cancer immunotherapy functions by reinforcing a patient's immune defense system to fight the disease. Clinically, promising immunotherapy approaches have, however, been limited by unpredictable response and strong adverse effects. A drug delivery system (DDS) that effectively targets tumor and reduces drug exposure to normal tissue would mitigate these limitations. In this regard, nanotechnology has been intensively studied as a DDS for targeting tumors with various oncologic drugs. Several have resulted in improved treatment and outcome. Research has shown that nanoparticle drug delivery technologies can also be applied to immunotherapy. In this review, the current state of nanotechnology will be discussed. Because most cancer immunotherapies approved in recent years are protein drugs, this article will focus on a micellar nanocomplex (MNC) technology, a DDS platform especially suited for targeted delivery of these therapeutics to solid tumors.

Arginine starvation kills tumor cells through aspartate exhaustion and mitochondrial dysfunction

Defective arginine synthesis, due to the silencing of argininosuccinate synthase 1 (ASS1), is a common metabolic vulnerability in cancer, known as arginine auxotrophy. Understanding how arginine depletion kills arginine-auxotrophic cancer cells will facilitate the development of anti-cancer therapeutic strategies. Here we show that depletion of extracellular arginine in arginine-auxotrophic cancer cells causes mitochondrial distress and transcriptional reprogramming. Mechanistically, arginine starvation induces asparagine synthetase (ASNS), depleting these cancer cells of aspartate, and disrupting their malate-aspartate shuttle. Supplementation of aspartate, depletion of mitochondria, and knockdown of ASNS all protect the arginine-starved cells, establishing the causal effects of aspartate depletion and mitochondrial dysfunction on the arginine starvation-induced cell death. Furthermore, dietary arginine restriction reduced tumor growth in a xenograft model of ASS1-deficient breast cancer. Our data challenge the view that ASNS promotes homeostasis, arguing instead that ASNS-induced aspartate depletion promotes cytotoxicity, which can be exploited for anti-cancer therapies.

Autophagic reliance promotes metabolic reprogramming in oncogenic KRAS-driven tumorigenesis

Defects in basal autophagy limit the nutrient supply from recycling of intracellular constituents. Despite our understanding of the prosurvival role of macroautophagy/autophagy, how nutrient deprivation, caused by compromised autophagy, affects oncogenic KRAS-driven tumor progression is poorly understood. Here, we demonstrate that conditional impairment of the autophagy gene Atg5 (atg5-KO) extends the survival of KRASG12V-driven tumor-bearing mice by 38%. atg5-KO tumors spread more slowly during late tumorigenesis, despite a faster onset. atg5-KO tumor cells displayed reduced mitochondrial function and increased mitochondrial fragmentation. Metabolite profiles indicated a deficiency in the nonessential amino acid asparagine despite a compensatory overexpression of ASNS (asparagine synthetase), key enzyme for de novo asparagine synthesis. Inhibition of either autophagy or ASNS reduced KRASG12V-driven tumor cell proliferation, migration, and invasion, which was rescued by asparagine supplementation or knockdown of MFF (mitochondrial fission factor). Finally, these observations were reflected in human cancer-derived data, linking ASNS overexpression with poor clinical outcome in multiple cancers. Together, our data document a widespread yet specific asparagine homeostasis control by autophagy and ASNS, highlighting the previously unrecognized role of autophagy in suppressing the metabolic barriers of low asparagine and excessive mitochondrial fragmentation to permit malignant KRAS-driven tumor progression.

[The Use of Informed Consent in Clinical Nursing Practice]

Obtaining informed consent and ensuring patient autonomy are critical to implementing a patient-centered model of healthcare. Informed consent is a complex process of communication that includes three elements: disclosure, competence in making decisions, and voluntariness. However, individual patient factors, doctor-patient interaction, and cultural issues are known to influence the process of obtaining informed consent. Individual patient factors include the ability of patients to understand and determine their intent; doctor-patient interaction includes communication skills; and cultural issues include the expectations of patients with regard to family involvement in medical decision-making and in decision-making motives. After assessing the relevant influencing factors, healthcare providers typically provide patients with comprehensive information on the benefits and risks of treatment as well as related alternatives. Moreover, healthcare providers typically provide patients with audio/video, Internet, and written information with illustrations based on individual patient needs. In addition to the above, we suggest that healthcare providers proactively adopt the perspective of patients in order to better encourage patients to address questions, to engage with patients in more productive discussions, and to take the initiative to explain and clarify patients' questions in order to minimize anxiety. This approach will help ensure that patients are adequately informed and free from coercion so that they make appropriate healthcare-related decisions. However, even under this optimal situation, healthcare providers must emphasize the needs of their patients and respect their decisions.

A Practical Standardized Composite Nutrition Score Based on Lean Tissue Index: Application in Nutrition Screening and Prediction of Outcome in Hemodialysis Population

OBJECTIVE

Rapid screening and monitoring of nutritional status is mandatory in hemodialysis population because of the increasingly encountered nutritional problems. Considering the limitations of previous composite nutrition scores applied in this population, we tried to develop a standardized composite nutrition score (SCNS) using low lean tissue index as a marker of protein wasting to facilitate clinical screening and monitoring and to predict outcome.

DESIGN AND METHODS

This retrospective cohort used 2 databases of dialysis populations from Taiwan between 2011 and 2014. First database consisting of data from 629 maintenance hemodialysis patients was used to develop the SCNS and the second database containing data from 297 maintenance hemodialysis patients was used to validate this developed score.

RESULTS

SCNS containing albumin, creatinine, potassium, and body mass index was developed from the first database using low lean tissue index as a marker of protein wasting. When applying this score in the original database, significantly higher risk of developing protein wasting was found for patients with lower SCNS (odds ratio 1.38 [middle tertile vs highest tertile, P < .0001] and 2.40 [lowest tertile vs middle tertile, P < .0001]). The risk of death was also shown to be higher for patients with lower SCNS (hazard ratio 4.45 [below median level vs above median level, P < .0001]). These results were validated in the second database.

CONCLUSION

We developed an SCNS consisting of 4 easily available biochemical parameters. This kind of scoring system can be easily applied in different dialysis facilities for screening and monitoring of protein wasting. The wide application of body composition monitor in dialysis population will also facilitate the development of specific nutrition scoring model for individual facility.

Metabolic Stress-Induced Phosphorylation of KAP1 Ser473 Blocks Mitochondrial Fusion in Breast Cancer Cells

Mitochondrial dynamics during nutrient starvation of cancer cells likely exert profound effects on their capability for metastatic progression. Here, we report that KAP1 (TRIM28), a transcriptional coadaptor protein implicated in metastatic progression in breast cancer, is a pivotal regulator of mitochondrial fusion in glucose-starved cancer cells. Diverse metabolic stresses induced Ser473 phosphorylation of KAP1 (pS473-KAP1) in a ROS- and p38-dependent manner. Results from live-cell imaging and molecular studies revealed that during the first 6 to 8 hours of glucose starvation, mitochondria initially underwent extensive fusion, but then subsequently fragmented in a pS473-KAP1-dependent manner. Mechanistic investigations using phosphorylation-defective mutants revealed that KAP1 Ser473 phosphorylation limited mitochondrial hyperfusion in glucose-starved breast cancer cells, as driven by downregulation of the mitofusin protein MFN2, leading to reduced oxidative phosphorylation and ROS production. In clinical specimens of breast cancer, reduced expression of MFN2 corresponded to poor prognosis in patients. In a mouse xenograft model of human breast cancer, there was an association in the core region of tumors between MFN2 downregulation and the presence of highly fragmented mitochondria. Collectively, our results suggest that KAP1 Ser473 phosphorylation acts through MFN2 reduction to restrict mitochondrial hyperfusion, thereby contributing to cancer cell survival under conditions of sustained metabolic stress. Cancer Res; 76(17); 5006-18. ©2016 AACR.

KAPtain in charge of multiple missions: Emerging roles of KAP1

KAP1/TRIM28/TIF1β was identified nearly twenty years ago as a universal transcriptional co-repressor because it interacts with a large KRAB-containing zinc finger protein (KRAB-ZFP) transcription factor family. Many studies demonstrate that KAP1 affects gene expression by regulating the transcription of KRAB-ZFP-specific loci, trans-repressing as a transcriptional co-repressor or epigenetically modulating chromatin structure. Emerging evidence suggests that KAP1 also functions independent of gene regulation by serving as a SUMO/ubiquitin E3 ligase or signaling scaffold protein to mediate signal transduction. KAP1 is subjected to multiple post-translational modifications (PTMs), including serine/tyrosine phosphorylation, SUMOylation, and acetylation, which coordinately regulate KAP1 function and its protein abundance. KAP1 is involved in multiple aspects of cellular activities, including DNA damage response, virus replication, cytokine production and stem cell pluripotency. Moreover, knockout of KAP1 results in embryonic lethality, indicating that KAP1 is crucial for embryonic development and possibly impacts a wide-range of (patho)physiological manifestations. Indeed, studies from conditional knockout mouse models reveal that KAP1-deficiency significantly impairs vital physiological processes, such as immune maturation, stress vulnerability, hepatic metabolism, gamete development and erythropoiesis. In this review, we summarize and evaluate current literatures involving the biochemical and physiological functions of KAP1. In addition, increasing studies on the clinical relevance of KAP1 in cancer will also be discussed.

TGFβ induces "BRCAness" and sensitivity to PARP inhibition in breast cancer by regulating DNA-repair genes

Transforming growth factor beta (TGFβ) proteins are multitasking cytokines, in which high levels at tumor sites generally correlate with poor prognosis in human patients with cancer. Previously, it was reported that TGFβ downregulates the expression of ataxia telangiectasia-mutated (ATM) and mutS homolog 2 (MSH2) in breast cancer cells through an miRNA-mediated mechanism. In this study, expression of a panel of DNA-repair genes was examined, identifying breast cancer 1, early onset (BRCA1) as a target downregulated by TGFβ through the miR181 family. Correlations between the expression levels of TGFβ1 and the miR181/BRCA1 axis were observed in primary breast tumor specimens. By downregulating BRCA1, ATM, and MSH2, TGFβ orchestrates DNA damage response in certain breast cancer cells to induce a "BRCAness" phenotype, including impaired DNA-repair efficiency and synthetic lethality to the inhibition of poly (ADP-ribose) polymerase (PARP). Xenograft tumors with active TGFβ signaling exhibited resistance to the DNA-damaging agent doxorubicin but increased sensitivity to the PARP inhibitor ABT-888. Combination of doxorubicin with ABT-888 significantly improved the treatment efficacy in TGFβ-active tumors. Thus, TGFβ can induce "BRCAness" in certain breast cancers carrying wild-type BRCA genes and enhance the responsiveness to PARP inhibition, and the molecular mechanism behind this is characterized.

IMPLICATIONS

These findings enable better selection of patients with sporadic breast cancer for PARP interventions, which have exhibited beneficial effects in patients carrying BRCA mutations.

Survival and other clinical outcomes of maintenance hemodialysis patients in Taiwan: a 5-year multicenter follow-up study

The increasing aging and diabetes mellitus (DM) patients in dialysis population make the quality maintenance of dialysis an imperative issue. Recently, an increasing number of dialysis centers were run by private dialysis providers, many of which apply quality assurance programs and performance management systems to dialysis care. We studied patients in dialysis facilities in Taiwan run by a private chain to see clinical outcomes of centers operating under these systemic strategies. Hemodialysis patients from January 1, 2008 to December 31, 2012 in 25 dialysis facilities in Taiwan, which received the management and consultation from a dialysis service provider, NephroCare (NC), were included. Data pivotal to quality of dialysis were analyzed. During a 5-year interval, 5161 hemodialysis patients were included. For volume control, the proportion of patients with weight gain ≥4.5% decreases from 41.7% to 30.2%. Mean Kt/V is 1.74 ± 0.28. Mean albumin level is 3.92 ± 0.38 g/dL. Patients with phosphate <5.5 mg/dL is up to 71.8%. The mean hemoglobin level is 10.70 ± 1.40 g/dL. More than 80% of patients have adequate iron status. Further, 73% of patients use native arteriovenous fistula. Hospitalization-free survival rate was 56% at the fifth year. Patient survival rate at the fifth year was 66.4%. Overall clinical performances were maintained very stable in NC facilities from this temporal data analysis. The hospitalization and survival rate also compare favorably with those reported internationally. These results warrant further studies to justify the application of this kind of quality assurance programs and performance management systems in dialysis care.

Application of Bioimpedance Spectroscopy in Asian Dialysis Patients (ABISAD): serial follow-up and dry weight evaluation

BACKGROUND

Maintenance of the optimal fluid status in hemodialysis patients is still a challenging task in daily clinical practice. A bioelectric impedance technique has been applied for evaluation of hydration status in the dialysis population in recent years, but serial observations of its role in clinical dry weight determination are lacking. In this study, serial follow-up data of a body composition monitor based on bioimpedance spectroscopy (BCM-BIS) applied in dialysis patients were analyzed to define the technique's feasibility, precision and possible role in dry weight determination.

METHODS

BCM-BIS was applied monthly to 194 hemodialysis patients for 6 months. Intra-patient precision was analyzed. Bland-Altman analysis and repeated-measures analysis of variance (ANOVA) were used to define the relationship between the dry weights determined by BCM-BIS and by clinical judgment.

RESULTS

The coefficients of variation (CVs) of fluid parameters were <5%. Serial changes in dry weight differences were compared in groups with different post-dialysis hydration status and dry weight differences decreased gradually. Bland-Altman analysis revealed that the range of these differences was significantly narrower towards the latter part of the study. The upper limit of agreement with 95% confidence interval (CI) was 1.47 L and the lower limit was -3.02 L.

CONCLUSIONS

BCM-BIS is precise and can be easily applied in the clinical setting. Discrepancy between the dry weights determined by BCM-BIS and by clinical judgment significantly decreased during the study. It is sensitive in dry weight determination, especially for those patients with obvious over-hydration (OH) by BCM-BIS. Patients with post-dialysis OH results beyond some critical values (>1.5 L or <-3 L) should be closely monitored.

A CD14 promoter polymorphism is associated with CD14 expression and Chlamydia-stimulated TNFα production

CD14, a pattern recognition receptor on monocyte and macrophage, plays a central role in innate immunity through recognition of bacterial lipopolysaccharide and initiation of inflammatory response. Recently, CD14/-260C>T promoter gene polymorphism has been found to be related to a risk of inflammatory diseases. Our results showed that the C allele frequency among Chinese in Taiwan was lower than those in Western countries. The membrane CD14 expression was significantly higher in TT as compared with CT and CC genotypes (P=0.034, 0.044, respectively). There was a higher level of soluble CD14 in TT and CT genotypes than in CC genotypes. In addition, TNFalpha production in whole blood was significantly higher in TT genotype than in CC genotype after stimulation by Chlamydiae. In conclusion, the single base pair polymorphism of CD14 promoter gene is associated with CD14 expression and Chlamydia-stimulated TNFalpha production, and may thus play some role in the chlamydia-induced inflammatory response.

Synthesis and DNA nicking studies of a novel cyclic peptide: cyclo[Lys-Trp-Lys-Ahx-]

Two novel cyclic tetrapeptides: cyclo[Lys-Tyr-Lys-Ahx-] 7a and cyclo[Lys-Trp-Lys-Ahx-] 7b were synthesized by coupling protected amino acid in solution and the subsequent cyclization effected by the pentafluorophenyl ester method as described in previous papers. These cyclic peptides were designed and synthesized to study their interaction with DNA, based on previous reports that linear peptides Lys-Tyr-Lys and Lys-Trp-Lys could bind to various forms of DNA and cleaved supercoiled DNA at apurinic sites. Ethidium bromide displacement assay showed that the apparent DNA binding constant of linear Lys-Tyr-Lys and cyclic peptide 7a are far below 1 x 10(3) M(-1), whereas those of cyclic peptide 7b and linear Lys-Trp-Lys are 1.9 x 10(4) M(-1) and 9.5 x 10(3) M(-1), respectively. Kinetic studies using agarose gel electrophoresis showed that cyclic peptide 7b and Lys-Trp-Lys possessed DNA nicking activity on natural supercoiled phi X174 DNA with nicking rate of 50.7 and 75.6 pM min(-1) at 65 degrees C, respectively, whereas cyclic peptide 7a and linear Lys-Tyr-Lys were devoid of the corresponding activity. The DNA nicking rate increased significantly with increase in reaction temperature. At reaction temperatures lower than 65 degrees C, the DNA nicking rate of cyclic peptide 7b exceeded that of linear Lys-Trp-Lys. The addition of 1 microM ferrous ion did not give significant enhancement effect on the DNA nicking rate by the peptides. UV irradiation gave a marked rate enhancement on the DNA nicking rate of linear Lys-Trp-Lys and a moderate enhancement on the DNA nicking rate of cyclic peptide 7b.

Quantitative analysis of the effects of audio biofeedback on weight-bearing characteristics of persons with transtibial amputation during early prosthetic ambulation

Residual limb recovery after a transtibial amputation depends largely on close monitoring of the weight-bearing activities during the early postoperative stage. Although a biofeedback device, in particular audio biofeedback, was recommended to be used, no quantitative studies regarding its effectiveness in monitoring the weight-bearing activity of a person with amputation were available. In this study, six persons with transtibial amputation were asked to replicate a prescribed amount of weight bearing using a bathroom scale method during their early postoperative ambulatory training. Their weight-bearing characteristics with and without using audio biofeedback were continuously monitored using a load monitoring device and compared with the prescribed load. The results showed that the residual limb would be overloaded using the conventional bathroom scale method during early postoperative ambulatory training if no audio biofeedback was provided. It was demonstrated that audio biofeedback was useful in preventing the residual limb from being overloaded beyond the prescribed load particularly when the prescribed load was low.

Perak, Malaysia, mass poisoning. Tale of the Nine Emperor Gods and rat tail noodles

In October 1988, a series of food poisoning cases occurred in the State of Perak in Malaysia. Most of the victims were children. Ultimately 13 children between the ages of 2.5 and 11 years died. Epidemiological investigations showed that the probable source of the poison was Loh See Fun, a noodles in the shape of a rat's tail. All the deceased ate the noodles from one supplier. Clinical and pathological findings were similar in each case. Postmortem examination was performed in 11 cases. Toxicological examination on organs in 10 cases showed a high concentration of aflatoxin in tissues of the deceased. High levels of boric acid were excreted from most of the victims. Histological examination of the liver in these cases showed necrotic changes found in aflatoxin poisoning. Combination of the epidemiological, clinical, toxicological, and pathological findings pointed to the fact that there was a common toxin or toxins responsible for the deaths. These were thought to be a combination of boric acid and aflatoxin.

Reduction of serum calcium by sodium sulfonated polystyrene resin

Sodium resin has been clinically administered against hyperkalemia widely, but its effects of lowering the serum calcium has never been documented. In our study, 7 patients with chronic renal failure were chosen at random to take sodium resin 30 g per day for 3 days. The sodium resin not only lowered the serum potassium level (p less than 0.05) but also brought down the level of serum calcium (p less than 0.05). The reduced ability of patients with chronic renal failure to absorb calcium from the gastrointestinal tract is well recognized, so its effects of lowering calcium will be more likely to aggravate the serum calcium imbalance further. If sodium resin has to be used for the maintainance of serum potassium in patients with chronic renal failure the serum calcium should be monitored closely in order to lighten the osteodystrophy and secondary hyperparathyroidism.

Skull and photographic superimposition: a new approach using a second party's interpupil distance to extrapolate the magnification factor

The photographic superimposition technique requires an antemortem photograph to be enlarged to life size and the skull to be photographed from the same angle as the antemortem photograph. This paper describes how the magnification factor can be extrapolated by measuring the true interpupil distance of a second person and the photographic interpupil distance of the suspect and the second party. A closed-circuit television (CCTV) system is used to determine quickly the skull photographic angle. We believe these techniques are viable and easy to perform.

Acute thrombosis of Starr-Edwards aortic prosthesis

A case of acute valve thrombosis occurring in a Starr-Edwards aortic prosthesis during the immediate postoperative period is reported. This appears to be the first such case to be reported.

Serum C1q concentrations in rheumatic disorders. Early normalization during treatment of immunologically-mediated vasculitis

Serum C1q concentrations were studied in 78 patients with definite and classical rheumatoid arthritis (RA). No correlation could be made either with disease activity, with erythrocyte sedimentation rate or with rheumatoid factor titers. In contrast to these findings in RA, however, serial determinations of this complement component were of value in predicting the response to therapy in four patients with immunologically-mediated vasculitis. Initially both C1q and C3 were depressed in two patients with SLE, one with cryoglobulinemic purpura and one with HbsAg-positive serum sickness, each with acute vasculitis. Sequential studies following the institution of treatment showed in each case that C1q returned to normal while C3 remained low. These observations suggest that analysis of serum C1q is preferable to C3 in these disorders when used to predict clinical change and the response to treatment.