Unraveling the underlying mechanisms of reduced amyloidogenic properties in human calcitonin via double mutations.

The therapeutic efficacy of peptide-based drugs is commonly hampered by the intrinsic propensity to aggregation. A notable example is human calcitonin (hCT), a peptide hormone comprising 32 amino acids, which is synthesized and secreted by thyroid gland parafollicular cells (C cells). This hormone plays a vital role in regulating blood calcium levels and upholding bone integrity. Despite its physiological importance, utilizing hCT as a drug is hampered by its inclination to form amyloid. To address this limitation, an alternative is provided by salmon calcitonin (sCT), which possesses a lower aggregation propensity. Although sharing the same disulfide bond at the N terminus as hCT, sCT differs from hCT at a total of 16 amino acid positions. However, due to the dissimilarity in sequences, using sCT as a clinical replacement occasionally results in adverse side effects in patients. Earlier investigations have highlighted the significant roles of Tyr-12 and Asn-17 in inducing the formation of amyloid fibrils. By introducing double mutations at these sites, the ability to hinder aggregation can be significantly augmented. This study delves into the oligomerization and helical structure formation of the hCT double mutant (Y12LN17H hCT, noted as DM hCT), as well as two single mutants (Y12L and N17H), aiming to elucidate the mechanism behind hCT fibrillization. In addition, computational prediction tools were employed again to identify potential substitutes. Although the results yielded were not entirely satisfactory, a comparison between the newly examined and previously found hCT double mutants provides insights into the reduced aggregation propensity of the latter. This research endeavor holds the promise of informing the design of more effective therapeutic peptide drugs in the future.

Hematologic and Serum Biochemical Values Associated With Different Stages of Hospital-Acquired Pressure Injuries in Patients: A Retrospective Study.

PURPOSE: The primary purpose of this study was to determine whether hematologic and serum biochemical values used as indicators of nutritional status, anemia, and/or infection were associated with the risk of hospital-acquired pressure injuries (PIs) and stage of PIs in patients. DESIGN: A retrospective review of medical records. SUBJECTS AND SETTING: Data were collected from medical records including official PI records and PI incident reports of inpatients at a teaching hospital in Taiwan between January 2019 and October 2020. METHODS: We collected demographic variables of the inpatients and their hematologic and serum biochemical values within 1 day of PI occurrence (including the day of PI occurrence), 6 to 7 days before PI occurrence, and 13 to 14 days before PI occurrence. RESULTS: Among the 309 inpatients with official PI records, 105 (34.0%) had Stage 1 PIs, 131 (42.4%) had Stage 2 or 3 PIs, and 73 (23.6%) had unstageable or suspected deep tissue injuries. After controlling for the type of department where PIs occurred and length of hospital stay up to the day of PI occurrence, we found significant differences in levels of hemoglobin (odds ratio [OR] = 0.47, P = .009) within 1 day of PI occurrence and in albumin (OR = 0.30, P = .001) 13 to 14 days before PI occurrence. CONCLUSIONS: Study findings suggest that lower hemoglobin levels on the day of PI occurrence and lower albumin levels 2 weeks before PI occurrence resulted in a significantly higher risk of developing unstageable or suspected deep tissue injuries than of developing Stage 1 PIs.

Klebsiella pneumoniae K2 capsular polysaccharide degradation by a bacteriophage depolymerase does not require trimer formation.

K2-capsular Klebsiella pneumoniae is a hypervirulent pathogen that causes fatal infections. Here, we describe a phage tailspike protein, named K2-2, that specifically depolymerizes the K2 capsular polysaccharide (CPS) of K. pneumoniae into tetrasaccharide repeating units. Nearly half of the products contained O-acetylation, which was thought crucial to the immunogenicity of CPS. The product-bound structures of this trimeric enzyme revealed intersubunit carbohydrate-binding grooves, each accommodating three tetrasaccharide units of K2 CPS. The catalytic residues and the key interactions responsible for K2 CPS recognition were identified and verified by site-directed mutagenesis. Further biophysical and functional characterization, along with the structure of a tetrameric form of K2-2, demonstrated that the formation of intersubunit catalytic center does not require trimerization, which could be nearly completely disrupted by a single-residue mutation in the C-terminal domain. Our findings regarding the assembly and catalysis of K2-2 provide cues for the development of glycoconjugate vaccines against K. pneumoniae infection. IMPORTANCE: Generating fragments of capsular polysaccharides from pathogenic bacteria with crucial antigenic determinants for vaccine development continues to pose challenges. The significance of the C-terminal region of phage tailspike protein (TSP) in relation to its folding and trimer formation remains largely unexplored. The polysaccharide depolymerase described here demonstrates the ability to depolymerize the K2 CPS of K. pneumoniae into tetrasaccharide fragments while retaining the vital O-acetylation modification crucial for immunogenicity. By carefully characterizing the enzyme, elucidating its three-dimensional structures, conducting site-directed mutagenesis, and assessing the antimicrobial efficacy of the mutant enzymes against K2 K. pneumoniae, we offer valuable insights into the mechanism by which this enzyme recognizes and depolymerizes the K2 CPS. Our findings, particularly the discovery that trimer formation is not required for depolymerizing activity, challenge the current understanding of trimer-dependent TSP activity and highlight the catalytic mechanism of the TSP with an intersubunit catalytic center.

Risk, Predictive, and Preventive Factors for Noninfectious Ventriculitis and External Ventricular Drain Infection.

BACKGROUND: External ventricular drain (EVD) is used for monitoring intracranial pressure or diverting cerebrospinal fluid. However, confirmation of an infection is not immediate and requires obtaining culture results, often leading to the excessive use of antibiotics. This study aimed to compare noninfectious ventriculitis and EVD infection in terms of the risk factors, predictors, prognosis, and effectiveness of care bundle interventions. METHODS: This retrospective study was conducted at a medical center with 1,006 beds in northern Taiwan between January 2018 and July 2022. Standard EVD insertion protocols and care bundles have been implemented since 2018, along with the initiation of chlorhexidine. RESULTS: In total, 742 EVD cases were identified. Noninfectious ventriculitis typically presents with fever approximately 8 days following EVD placement, whereas EVD infection typically manifests as fever after 20 days. Aneurysmal subarachnoid hemorrhage was strongly associated with the development of noninfectious ventriculitis (adjusted odds ratio [OR] 2.6, 95% confidence interval [CI] 1.5-4.4). Alcoholism (adjusted OR 3.5, 95% CI 1.1-12.3) and arteriovenous malformation (adjusted OR 13.1, 95% CI 2.9-58.2) significantly increased the risk of EVD infection. The EVD infection rate significantly decreased from 3.6% (14 of 446) to 1.0% (3 of 219) (p = 0.03) after the implementation of chlorhexidine gluconate bathing. CONCLUSIONS: Aneurysmal subarachnoid hemorrhage or fever with neuroinflammation within 2 weeks of EVD placement is indicative of a higher likelihood of noninfectious ventriculitis. Conversely, patients with arteriovenous malformation, alcoholism, or fever with neuroinflammation occurring after more than 3 weeks of EVD placement are more likely to necessitate antibiotic treatment for EVD infection. Chlorhexidine gluconate bathing decreases EVD infection.

Investigating the inhibitory property of DM hCT on hCT fibrillization via its relevant peptide fragments.

The irreversible aggregation of proteins or peptides greatly limits their bioavailability; therefore, effective inhibition using small molecules or biocompatible materials is very difficult. Human calcitonin (hCT), a hormone polypeptide with 32 residues, is secreted by the C-cells of the thyroid gland. The biological function of this hormone is to regulate calcium and phosphate concentrations in the blood via several different pathways. One of these is to inhibit the activity of osteoclasts; thus, calcitonin could be used to treat osteoporosis and Paget's disease of the bone. However, hCT is prone to aggregation in aqueous solution and forms amyloid fibrils. Salmon and eel calcitonin are currently used as clinical substitutes for hCT. In a previous study, we found that the replacement of two residues at positions 12 and 17 of hCT with amino acids that appear in the salmon sequence can greatly suppress peptide aggregation. The double mutations of hCT (DM hCT) also act as good inhibitors by disrupting wild-type hCT fibrillization, although the inhibition mechanism is not clear. More importantly, we demonstrated that DM hCT is biologically active in interacting with the calcitonin receptor. To further understand the inhibitory effect of DM hCT on hCT fibrillization, we created four relevant peptide fragments based on the DM hCT sequence. Our examination revealed that the formation of a helix of DM hCT was possibly a key component contributing to its inhibitory effect. This finding could help in the development of peptide-based inhibitors and in understanding the aggregation mechanism of hCT.

Correlation between Component Factors of Non-Alcoholic Fatty Liver Disease and Metabolic Syndrome in Nurses: An Observational and Cross-Sectional Study.

This study aimed to understand the correlation between non-alcoholic fatty liver disease (NAFLD) and metabolic syndrome in nurses. Questionnaires were used to eliminate individuals with a daily drinking habit, hepatitis B or C, or incomplete data. A total of 706 valid samples were obtained. The prevalence of NAFLD among nurses was 36.8%. Nurses with a greater age (OR = 1.08, 95% CI: 1.01-1.16), obese BMI (OR = 23.30, 95% CI: 8.88-61.10), overweight BMI (OR = 3.89, 95% CI: 2.15-7.04), waist circumference exceeding the standard (OR = 2.10, 95% CI: 1.14-3.87), fasting blood glucose 100-125 mg/dL (OR = 4.09, 95% CI: 1.19-14.03), and overly low HDL-C (OR = 2.01, 95% CI: 1.05-3.85) were at greater risk of NAFLD. Furthermore, male nurses (OR = 6.42, 95% CI: 1.07-38.70), nurses with triglycerides over 150 mg/dL (OR = 4.80; 95% CI: 1.05-21.95), and nurses with HDL-C lower than the standard (OR = 5.63, 95% CI: 1.35-23.49) were at greater risk of moderate/severe NAFLD. Among younger nurses, those of greater age, male nurses, obese and overweight nurses, and those with a waist circumference exceeding the standard, 100-125 mg/dL, overly low HDL-C, and triglycerides over 150 mg/dL should consider the possibility that they have NAFLD.

Development of Klebsiella pneumoniae Capsule Polysaccharide-Conjugated Vaccine Candidates Using Phage Depolymerases.

Klebsiella pneumoniae is an important pathogen associated with nosocomial infection and has developed increasing resistance to antibiotics such as extended-spectrum ß-lactams and carbapenem. In recent years, K. pneumoniae isolates have emerged as a major cause of global community-acquired infections such as pneumonia and pyogenic liver abscess. Although serotypes K1 and K2 have been identified as the predominant capsular types associated with invasive infections, no K. pneumoniae vaccine is commercially available, probably due to immunogenicity loss in the traditional depolymerization method to obtain capsule polysaccharide (CPS) for the preparation of conjugated vaccine. In this study, we successfully retained immunogenicity by using K1 (K1-ORF34) and K2 (K2-ORF16) CPS depolymerases that were identified from phages to cleave K1 and K2 CPSs into intact structural units of oligosaccharides with intact modifications. The obtained K1 and K2 oligosaccharides were separately conjugated with CRM197 carrier protein to generate CPS-conjugated vaccines. Immunization experiments of mice showed both K1 and K2 CPS-conjugated vaccines induced anti-CPS antibodies with 128-fold and 64-fold increases of bactericidal activities, respectively, compare to mice without vaccinations. Challenge tests indicated that K1 or K2 CPS-conjugated vaccine and divalent vaccine (a mixture of K1 and K2 CPS-conjugated vaccines) protected mice from subsequent infection of K. pneumoniae by the respective capsular type. Thus, we demonstrated K1 and K2 CPS-conjugated vaccines prepared by CPS depolymerases is a promising candidate for developing vaccines against human K. pneumoniae infections.

Closer vein spacing by ectopic expression of nucleotide-binding and leucine-rich repeat proteins in rice leaves.

KEY MESSAGE: Elevated expression of nucleotide-binding and leucine-rich repeat proteins led to closer vein spacing and higher vein density in rice leaves. To feed the growing global population and mitigate the negative effects of climate change, there is a need to improve the photosynthetic capacity and efficiency of major crops such as rice to enhance grain yield potential. Alterations in internal leaf morphology and cellular architecture are needed to underpin some of these improvements. One of the targets is to generate a "Kranz-like" anatomy in leaves that includes decreased interveinal spacing close to that in C4 plant species. As C4 photosynthesis has evolved from C3 photosynthesis independently in multiple lineages, the genes required to facilitate C4 may already be present in the rice genome. The Taiwan Rice Insertional Mutants (TRIM) population offers the advantage of gain-of-function phenotype trapping, which accelerates the identification of rice gene function. In the present study, we screened the TRIM population to determine the extent to which genetic plasticity can alter vein density (VD) in rice. Close vein spacing mutant 1 (CVS1), identified from a VD screening of approximately 17,000 TRIM lines, conferred heritable high leaf VD. Increased vein number in CVS1 was confirmed to be associated with activated expression of two nucleotide-binding and leucine-rich repeat (NB-LRR) proteins. Overexpression of the two NB-LRR genes individually in rice recapitulates the high VD phenotype, due mainly to reduced interveinal mesophyll cell (M cell) number, length, bulliform cell size and thus interveinal distance. Our studies demonstrate that the trait of high VD in rice can be achieved by elevated expression of NB-LRR proteins limited to no yield penalty.

Meta-Analysis Comparing Menstrual Regularity and Dysmenorrhea of Women Working Rotating Shifts and Fixed Day Shifts.

Background: Rotating shift work can cause abnormalities in their endocrine system. We conducted a meta-analysis to gain a better understanding of the differences between women working rotating shifts and fixed day shifts in menstrual regularity and dysmenorrhea. Methods: We searched for studies containing relevant keywords that were published between 1990 and 2019 in the Cochrane Library, EBSCO (including the Cumulative Index to Nursing and Allied Health Literature [CINAHL]), MEDLINE, and ProQuest. Data analysis was performed using the software package Comprehensive Meta-Analysis (CMA) Version 3.0. Results: A total of 14 studies met our selection criteria. The pooled odds ratio (OR) comparing the menstrual irregularity of women working rotating shifts and fixed day shifts was 1.35 (95% confidence interval [CI]: 1.28-1.42, p < 0.001). The pooled OR of the women aged 30 years or older was 1.35 (95% CI: 1.28-1.42, p < 0.001); and for the women under 30 years old, the pooled OR was 1.66 (95% CI: 1.13-2.44, p = 0.010). The pooled OR comparing the dysmenorrhea occurrence among women working rotating shifts and fixed day shifts was 1.51 (95% CI: 0.87-2.62, p = 0.139). The pooled OR of the women aged 30 years or older was 2.35 (95% CI: 1.63-3.39, p < 0.001); and for the women under 30 years old, the pooled OR was 1.20 (95% CI: 0.61-2.33, p = 0.601). Conclusions: The results indicate that regardless of age, women working rotating shifts were more likely to experience menstrual irregularity than those working fixed day shifts. With regard to dysmenorrhea, among women aged 30 years or older, those working rotating shifts were also more likely to experience dysmenorrhea than those working fixed day shifts.

Meta-Analysis of Changes in Sleep Quality of Women with Breast Cancer before and after Therapy.

Cancer treatments may affect the sleep quality and even future quality of life of women with breast cancer. A meta-analysis was performed to understand the changes in the sleep quality of women with breast cancer during their treatment period. In a systematic literature review in compliance with the PRISMA guidelines, we searched for articles published between 2000 and 2018 in databases. A total of 12 study articles were included. The standardized mean differences of the pooling effect size of sleep quality between the period before treatment and 1-8 weeks, 9-16 weeks, 17-24 weeks, and 25-56 weeks after the commencement of treatment were -0.020, -0.162, 0.075, and 0.216, respectively. Although the differences were not statistically significant, in view of the heterogeneity among the studies, we conducted further analysis using a linear mixed effect model. The overall results indicated poorer sleep quality as time passed from the start of the first treatment (p = 0.014). The results of this study revealed that patients experienced better sleep quality in the initial months after the beginning of treatment; however, their sleep quality became poorer between 4 months to approximately 1 year after the beginning of treatment, compared with the sleep quality before treatment, and continued to decline rather than improve during the follow-up period.

Relationship between job satisfaction and sleep quality of female shift-working nurses: using shift type as moderator variable.

This study was to investigate the impact of job satisfaction as the independent variable and the type of shift as the moderator variable on the sleep quality of female shift-working nurses. The Minnesota Satisfaction Questionnaire (MSQ) short form and the Pittsburgh Sleep Quality Index (PSQI) were used as evaluation tools. The subjects in the study were female shift-working nurses from teaching hospitals in northern Taiwan. A total of 178 valid questionnaires were recovered. A hierarchical multiple regression (HMR) was used to test for the moderating effect of shift type. The results demonstrated that there was a negative correlation between the total score for general job satisfaction and the Global PSQI scores. The Global PSQI scores were higher for nurses working night shifts than for those working day and evening shifts. HMR showed significant variances in the interaction between general job satisfaction of female shift-working nurses and the day/night shift as well as the evening/night shift. The type of shift had a moderating effect on the ways in which general job satisfaction impacts sleep quality. Furthermore, the moderating effect of night shift on the impact of job satisfaction on sleep quality was weaker in nurses working the night shift.

Pseudaminic Acid on Exopolysaccharide of Acinetobacter baumannii Plays a Critical Role in Phage-Assisted Preparation of Glycoconjugate Vaccine with High Antigenicity.

Pseudaminic acid (Pse) has been known for participating in crucial bacterial virulence and thus is an attractive target in the development of glycoconjugate vaccine. Particularly, this therapeutic alternative was suggested to be a potential solution against antibiotic resistant Acinetobacter baumannii that poses a serious global health threat. Also, Pse was found to be involved in the exopolysaccharide (EPS) of mild antibiotic resistant A. baumannii strain 54149 ( Ab-54149) of which specific glycosyl linkage can be depolymerized by phage ΦAB6 tailspike protein (ΦAB6TSP). In this study, we found that the antibodies induced by Ab-54149 EPS was capable of recognizing a range of EPS of other clinical A. baumannii strains, and deemed as a great potential material for vaccination. To efficiently acquire homogeneous EPS-derived oligosaccharide with significant immunogenic activity for the production of glycoconjugate, we used the ΦAB6TSP for the fragmentation of Ab-54149 EPS instead of chemical methods. Moreover, insight into the ligand binding characterization of ΦAB6TSP suggested the branched Pse on the Ab-54149 EPS served as a recognition site of ΦAB6TSP. The serum boosted by ΦAB6TSP-digested product and carrier protein CRM197 conjugate complex displayed specific sensitivity toward Ab-54149 EPS with bacterial killing activity. Strikingly, Pse is an ideal epitope with strong antigenicity, profiting the application of the probe for pathogen detection and glyco-based vaccine.

Counter-current chromatography using hexane/surfactant-containing water solvent systems.

We developed a n-hexane/surfactant-containing water solvent system in counter-current chromatography (CCC) in order to separate hydrophobic compounds. By using the upper phase as the mobile phase, we have separated steroid samples. Retention times of steroids progesterone and delta4-androstene-3,17-dione increased slightly by increasing the concentration below the critical micellar concentration (CMC) of surfactant sodium 1-heptanesulfonate. However, the retention times increased drastically while the SHS concentrations were above the CMC. The partition of these two steroids in the two phases was significantly dependent on the interaction with micelles. Aromatic hydrocarbons were not retained by the lower phase no matter what the surfactant concentrations were. Their hydrophobic interaction with n-hexane greatly exceeded that with the micellar solution. The retention times of esters, however, were only slightly affected by the surfactant addition even above the CMC. The weaker interaction between esters and the micellar solution was probably due to their higher polarity. The micellar solvent systems provide an alternative way for hydrophobic sample separations in CCC, but the performance is limited.