Chemotherapy dose per kilogram lean body mass increased dose-limiting toxicity event in male head and neck cancer with taxane and platinum-based induction therapy.

BACKGROUND: This study aimed to determine whether drug doses per kilogram of lean body mass (LBM) were associated with dose-limiting toxicity (DLT) events in head and neck cancer (HNC) patients. METHODS: This retrospective cohort study included 179 HNC patients who underwent induction chemotherapy (IC) at a medical center from May 1, 2014, to May 31, 2021. HNC patients' characteristics, tumor factors, IC regimen and dose, laboratory data, and body composition factors, including lean body mass (LBM) and skeletal muscle index (SMI), derived from CT, MRI, or PET scan images and drug dose per kilogram LBM were recorded. Dose-limiting toxicity (DLT) events were regarded as the primary outcome. Multivariate logistic regression was used to establish a novel risk score for DLT events by the abovementioned variables. The above-mentioned risk score was validated in another cohort. RESULTS: The overall DLT events during the first cycle of IC for 179 HNC patients was 24%. After stratifying by gender, docetaxel per kilogram LBM > 2.52 mg/kg (adjusted odds ratio [aOR]: 3.18; 95% confidence interval [CI], 1.25-8.09), pre-treatment glutamic pyruvic transaminase (GPT) > 40 U/L (aOR, 2.61; 95% CI, 1.03-6.64), and history of chronic liver diseases (aOR, 3.98; 95% CI, 1.03-15.46) were significant variables in male HNC patients. The DLT events risk was categorized by summation of the above-mentioned risk factors for male HNC patients. Three risk groups were stratified by overall event of 17.6%, 25.8%, and 75%. The above-mentioned risk score had an acceptable discriminatory ability in another validation cohort. CONCLUSIONS: Among male HNC patients treated with IC, docetaxel per kilogram LBM more than 2.52 mg/kg, pre-treatment GPT > 40 U/L, and history of chronic liver disease were significant risk factors for DLT events. Identifying high-risk patients could help physicians prevent severe/fatal complications among HNC patients undergoing IC, especially for the male individuals.

Learning Curve of Upper Aerodigestive Tract Foreign Body Management for Otorhinolaryngology Residents.

INTRODUCTION: Foreign body ingestion is the most common reason for otolaryngology specialist consultations in emergency departments. Among the different types of foreign bodies, fish bones are the most common, particularly in Asian populations. In Taiwan, upper aerodigestive tract foreign bodies (UADT-FBs) are mostly managed by residents in the otorhinolaryngology (ORL) department. Considering the learning curve required for all procedures, different management types between residents, and possible resulting safety issues, this study explored the outcomes of UADT-FB management by residents in different years of ORL training. MATERIALS AND METHODS: The medical records of 2,283 patients who visited Kaohsiung Veterans General Hospital's Emergency Department for UADT-FB during June 2013-August 2019 were retrospectively reviewed. The reviewed data included the demographic data of enrolled patients, outcomes of foreign body management, and follow-up chart records of the patients. RESULTS: Among the 2,283 patients, 1,324 (58%) were found to be negative for foreign bodies, and foreign bodies in 951 (41.7%) were removed immediately. In the negative finding (NF) group, 2 (4.9%) patients were later found to be positive for foreign bodies during follow-up in the outpatient department. One (2.4%) patient developed a deep neck infection and esophageal perforation. The percentage of NFs decreased from 62.58% in residents in the first half of their first year (R1a) to 54% for third-year residents (R3). Comparing R1a with R3, the number needed to harm for retained UADT-FBs after patients visited the emergency department was 12.2. DISCUSSION/CONCLUSION: This study provides data from 1 referral center regarding the management of UADT-FBs. With increasing resident training, the percentage of NFs declined from 62.58 to 54%. Young residents, especially those in the first 6 months of their training, should have senior residents perform a second examination if UADT-FBs are not found in suspected cases.

Replication-dependent and independent mechanisms for the chromosome-coupled persistence of a selfish genome.

The yeast 2-micron plasmid epitomizes the evolutionary optimization of selfish extra-chromosomal genomes for stable persistence without jeopardizing their hosts' fitness. Analyses of fluorescence-tagged single-copy reporter plasmids and/or the plasmid partitioning proteins in native and non-native hosts reveal chromosome-hitchhiking as the likely means for plasmid segregation. The contribution of the partitioning system to equal segregation is bipartite- replication-independent and replication-dependent. The former nearly eliminates 'mother bias' (preferential plasmid retention in the mother cell) according to binomial distribution, thus limiting equal segregation of a plasmid pair to 50%. The latter enhances equal segregation of plasmid sisters beyond this level, elevating the plasmid close to chromosome status. Host factors involved in plasmid partitioning can be functionally separated by their participation in the replication-independent and/or replication-dependent steps. In the hitchhiking model, random tethering of a pair of plasmids to chromosomes signifies the replication-independent component of segregation; the symmetric tethering of plasmid sisters to sister chromatids embodies the replication-dependent component. The 2-micron circle broadly resembles the episomes of certain mammalian viruses in its chromosome-associated propagation. This unifying feature among otherwise widely differing selfish genomes suggests their evolutionary convergence to the common logic of exploiting, albeit via distinct molecular mechanisms, host chromosome segregation machineries for self-preservation.

Histone H3-variant Cse4-induced positive DNA supercoiling in the yeast plasmid has implications for a plasmid origin of a chromosome centromere.

The Saccharomyces cerevisiae 2-µm plasmid is a multicopy selfish genome that resides in the nucleus. The genetic organization of the plasmid is optimized for stable, high-copy propagation in host-cell populations. The plasmid's partitioning system poaches host factors, including the centromere-specific histone H3-variant Cse4 and the cohesin complex, enabling replicated plasmid copies to segregate equally in a chromosome-coupled fashion. We have characterized the in vivo chromatin topology of the plasmid partitioning locus STB in its Cse4-associated and Cse4-nonassociated states. We find that the occupancy of Cse4 at STB induces positive DNA supercoiling, with a linking difference (ΔLk) contribution estimated between +1 and +2 units. One plausible explanation for this contrary topology is the presence of a specialized Cse4-containing nucleosome with a right-handed DNA writhe at a functional STB, contrasted by a standard histone H3-containing nucleosome with a left-handed DNA writhe at a nonfunctional STB. The similarities between STB and centromere in their nucleosome signature and DNA topology would be consistent with the potential origin of the unusual point centromere of budding yeast chromosomes from the partitioning locus of an ancestral plasmid.

Topological similarity between the 2µm plasmid partitioning locus and the budding yeast centromere: evidence for a common evolutionary origin?

The partitioning locus STB of the selfish plasmid, the 2µm circle, of Saccharomyces cerevisiae is essential for the propagation of this multi-copy extra-chromosomal DNA element with nearly chromosome-like stability. The functional competence of STB requires the plasmid-coded partitioning proteins Rep1 and Rep2 as well as host-coded proteins. Host factors that associate with STB in a Rep1- and Rep2-dependent manner also interact with centromeres, and play important roles in chromosome segregation. They include the cohesin complex and the centromere-specific histone H3 variant Cse4. The genetically defined point centromere of S. cerevisiae differs starkly from the much more widespread epigenetically specified regional centromeres of eukaryotes. The particularly small size of the S. cerevisiae centromere and the association of chromosome segregation factors with STB raise the possibility of an evolutionary link between these two partitioning loci. The unusual positive supercoiling harboured by the S. cerevisiae centromere and STB in vivo in their functional states, unveiled by recent experiments, bolsters the notion of their potential descent from an ancestral plasmid partitioning locus.

The kinase activity of the Helicobacter pylori Asp-tRNA(Asn)/Glu-tRNA(Gln) amidotransferase is sensitive to distal mutations in its putative ammonia tunnel.

The Helicobacter pylori (Hp) Asp-tRNA(Asn)/Glu-tRNA(Gln) amidotransferase (AdT) plays important roles in indirect aminoacylation and translational fidelity. AdT has two active sites, in two separate subunits. Kinetic studies have suggested that interdomain communication occurs between these subunits; however, this mechanism is not well understood. To explore domain-domain communication in AdT, we adapted an assay and optimized it to kinetically characterize the kinase activity of Hp AdT. This assay was applied to the analysis of a series of point mutations at conserved positions throughout the putative AdT ammonia tunnel that connects the two active sites. Several mutations that caused significant decreases in AdT's kinase activity (reduced by 55-75%) were identified. Mutations at Thr149 (37 Å distal to the GatB kinase active site) and Lys89 (located at the interface of GatA and GatB) were detrimental to AdT's kinase activity, suggesting that these mutations have disrupted interdomain communication between the two active sites. Models of wild-type AdT, a valine mutation at Thr149, and an arginine mutation at Lys89 were subjected to molecular dynamics simulations. A comparison of wild-type, T149V, and K89R AdT simulation results unmasks 59 common residues that are likely involved in connecting the two active sites.

Roles of amino acids in the Escherichia coli octaprenyl diphosphate synthase active site probed by structure-guided site-directed mutagenesis.

Octaprenyl diphosphate synthase (OPPS) catalyzes consecutive condensation reactions of farnesyl diphosphate (FPP) with five molecules of isopentenyl diphosphates (IPP) to generate C(40) octaprenyl diphosphate, which constitutes the side chain of ubiquinone or menaquinone. To understand the roles of active site amino acids in substrate binding and catalysis, we conducted site-directed mutagenesis studies with Escherichia coli OPPS. In conclusion, D85 is the most important residue in the first DDXXD motif for both FPP and IPP binding through an H-bond network involving R93 and R94, respectively, whereas R94, K45, R48, and H77 are responsible for IPP binding by providing H-bonds and ionic interactions. K170 and T171 may stabilize the farnesyl carbocation intermediate to facilitate the reaction, whereas R93 and K225 may stabilize the catalytic base (MgPP(i)) for H(R) proton abstraction after IPP condensation. K225 and K235 in a flexible loop may interact with FPP when the enzyme becomes a closed conformation, which is therefore crucial for catalysis. Q208 is near the hydrophobic part of IPP and is important for IPP binding and catalysis.

Recognition of tRNAGln by Helicobacter pylori GluRS2--a tRNAGln-specific glutamyl-tRNA synthetase.

Accurate aminoacylation of tRNAs by the aminoacyl-tRNA synthetases (aaRSs) plays a critical role in protein translation. However, some of the aaRSs are missing in many microorganisms. Helicobacter pylori does not have a glutaminyl-tRNA synthetase (GlnRS) but has two divergent glutamyl-tRNA synthetases: GluRS1 and GluRS2. Like a canonical GluRS, GluRS1 aminoacylates tRNA(Glu1) and tRNA(Glu2). In contrast, GluRS2 only misacylates tRNA(Gln) to form Glu-tRNA(Gln). It is not clear how GluRS2 achieves specific recognition of tRNA(Gln) while rejecting the two H. pylori tRNA(Glu) isoacceptors. Here, we show that GluRS2 recognizes major identity elements clustered in the tRNA(Gln) acceptor stem. Mutations in the tRNA anticodon or at the discriminator base had little to no impact on enzyme specificity and activity.

Trends in inpatient female urinary incontinence surgery and costs in Taiwan, 1997-2011.

OBJECTIVE: To explore the factors influencing the trends in incidence and cost for female inpatient urinary incontinence (UI) surgery from 1997 to 2011. MATERIALS AND METHODS: A dataset of one million individuals was randomly drawn from the nationwide National Health Insurance claim database covering Taiwan's population from 1997 to 2011. The participants consisted of women aged ≥20 years who underwent UI surgery. We evaluated the trends of inpatient UI incidence, the medical cost of UI surgery, and the number of UI surgeries performed from 1997 to 2011. RESULTS: A total of 1517 women underwent inpatient UI surgery from 1997 to 2011. Among these patients, the age-standardized incidence of UI surgery gradually trended upward from 1997 to 2010 but decreased in 2011. The trends were similar for medical costs, including annual inpatient cost, total medical service cost, and surgery fees. The annual inpatient cost had doubled in 2011 compared with that in 1997. However, physician visit fees, ward fees, and anesthesia fees started decreasing from 2005. The length of hospital stay and medication fees decreased during the 15-year study period. Surgeries by doctor specialty, hospital accreditation level, and patient age were stable for the study period. CONCLUSION: The trends of age-standardized incidence of UI surgery, annual inpatient cost, total inpatient cost, and surgery fees increased significantly from 1997 to 2009, and abruptly decreased from 2010 to 2011. Long-term observation evaluating the impact of Diagnosis-Related Group payment system in Taiwan is warranted to verify in the future.

Risk factors for urinary incontinence among women aged 60 or over with hypertension in Taiwan.

OBJECTIVE: To assess the associated risk factors and the prevalence of urinary incontinence (UI) among women with hypertension (H/T) aged 60 or over in Taiwan. MATERIALS AND METHODS: A total of 2410 women aged 60 or over were selected by a multistage random sampling method and a total of 1519 women completed the face-to-face interviews. Only women who answered "yes" to the question "Do you have H/T?" were included in the H/T sample. The factors were assessed by frequency and Pearson's χ(2) test using a significance level of p < 0.05. Logistic regression was used to investigate the significance of dichotomous dependent variables. RESULTS: A total of 39.7% (602 women) interviewees had H/T, among which 39.9% (240 women) had UI symptoms. The prevalence of UI among women aged 60 or over with or without H/T was significantly different (p = 0.006). Risk factors were age [odds ratio (OR) = 1.043, 95% confidence interval (CI) 1.016-1.071, per year], diabetes mellitus (DM) (OR = 1.653, 95% CI 1.105-2.474), previous urinary diseases (OR = 3.462, 95% CI 2.260-5.301), and body mass index (BMI; OR = 1.060, 95% CI 1.012-1.110, per unit). There was no significant association between UI and drug allergy, smoking, hysterectomy, hormone therapy, or gynecological surgery. CONCLUSION: UI can be a frequent and annoying problem for aged women. In women with H/T, UI is significantly related to risk factors such as age, DM, BMI, and urinary diseases. In addition, BMI is considered a key risk factor for H/T. Therefore, effective control of BMI would help in controlling H/T and UI in aged women.

The partitioning and copy number control systems of the selfish yeast plasmid: an optimized molecular design for stable persistence in host cells.

The multi-copy 2 micron plasmid of Saccharomyces cerevisiae, a resident of the nucleus, is remarkable for its high chromosome-like stability. The plasmid does not appear to contribute to the fitness of the host, nor does it impose a significant metabolic burden on the host at its steady state copy number. The plasmid may be viewed as a highly optimized selfish DNA element whose genome design is devoted entirely towards efficient replication, equal segregation and copy number maintenance. A partitioning system comprised of two plasmid coded proteins, Rep1 and Rep2, and a partitioning locus STB is responsible for equal or nearly equal segregation of plasmid molecules to mother and daughter cells. Current evidence supports a model in which the Rep-STB system promotes the physical association of the plasmid with chromosomes and thus plasmid segregation by a hitchhiking mechanism. The Flp site-specific recombination system housed by the plasmid plays a critical role in maintaining steady state plasmid copy number. A decrease in plasmid population due to rare missegregation events is rectified by plasmid amplification via a recombination induced rolling circle replication mechanism. Appropriate plasmid amplification, without runaway increase in copy number, is ensured by positive and negative regulation of FLP gene expression by plasmid coded proteins and by the control of Flp level/activity through host mediated post-translational modification(s) of Flp. The Flp system has been successfully utilized to understand mechanisms of site-specific recombination, to bring about directed genetic alterations for addressing fundamental problems in biology, and as a tool in biotechnological applications.

Molecular oxygen dependent steps in fatty acid oxidation by cyclooxygenase-1.

The mechanism by which cyclooxygenase-1 (COX-1), a heme- and tyrosyl radical-containing enzyme, catalyzes the regio- and stereospecific oxygenation of polyunsaturated fatty acids to prostaglandin or hydroperoxide products has not been understood. Steady-state kinetic studies conducted with the native substrate arachidonic acid and the slower substrate linoleic acid are described here. Second-order rate constants, kcat/KM for fatty acid and O2, are found to depend upon the concentration of the other cosubstrate. Competitive oxygen kinetic isotope effects (18O KIEs) kcat/KM(16,16O2)/kcat/KM(18,16O2) reveal that a peroxyl radical is formed in or before the first kinetically irreversible step. Together, the results indicate that the oxygenase reaction occurs by a sequential mechanism which most likely involves reversible abstraction of a hydrogen atom from the fatty acid prior to the trapping of the delocalized substrate radical by O2. The identity of the first kinetically irreversible step, subsequent to forming the peroxyl radical, is also discussed in the context of the magnitude of the oxygen kinetic isotope effects as well as the behavior of kcat/KM(O2) in response to changing solvent pH, pD, and viscosity.