Discovery of a New Class of Lipophilic Pyrimidine-Biphenyl Herbicides Using an Integrated Experimental-Computational Approach.

Herbicides are useful tools for managing weeds and promoting food production and sustainable agriculture. In this study, we report on the development of a novel class of lipophilic pyrimidine-biphenyl (PMB) herbicides. Firstly, three PMBs, Ia, IIa, and IIIa, were rationally designed via a scaffold hopping strategy and were determined to inhibit acetohydroxyacid synthase (AHAS). Computational simulation was carried out to investigate the molecular basis for the efficiency of PMBs against AHAS. With a rational binding mode, and the highest in vitro as well as in vivo potency, Ia was identified as a preferable hit. Furthermore, these integrated analyses guided the design of eighteen new PMBs, which were synthesized via a one-step Suzuki-Miyaura cross-coupling reaction. These new PMBs, Iba-ic, were more effective in post-emergence control of grass weeds compared with Ia. Interestingly, six of the PMBs displayed 98-100% inhibition in the control of grass weeds at 750 g ai/ha. Remarkably, Ica exhibited ≥ 80% control against grass weeds at 187.5 g ai/ha. Overall, our comprehensive and systematic investigation revealed that a structurally distinct class of lipophilic PMB herbicides, which pair excellent herbicidal activities with new interactions with AHAS, represent a noteworthy development in the pursuit of sustainable weed control solutions.

Translocation of two-dimensional active polymers through nanopores using Langevin dynamics simulations.

The translocation of polymers through nanopores is a complex process influenced by various factors. In this study, the translocation behavior of a two-dimensional active polymer chain, comprised of a head active Brownian particle (ABP) and a tail passive polymer chain, through a nanopore is studied using Langevin dynamics simulations. Results show that the effect of the self-propulsion force of the ABP on the translocation differs significantly from the driving force inside the pore for traditional polymer translocations. Specifically, the translocation time τ initially increases with increasing the magnitude fs of the self-propulsion force and then decreases with a further increase in fs. A small fs lowers the potential barrier for the translocation and thus promotes slow translocations, whereas a large fs directly pulls the polymer chain through the nanopore following the scaling relation τ ∝ fs-1. Moreover, two asymptotic scaling relations between τ and polymer length N, τ ∝ Nα, are found, with the exponent α of about 2.5 for small fs or long N and the exponent α of about 1.4 for short active polymers with large fs. We discover that the slow rotation of the ABP accelerates the translocation process.

Adsorption of active polymers on attractive nanoparticles.

The adsorption of active polymers on an attractive nanoparticle (NP) is studied using Langevin dynamics simulations. The active polymers consist of an active Brownian particle (ABP) at the head and a subsequent passive polymer chain. The ABP experiences an active force of magnitude Fa. The interactions between the active polymer and NP are modeled as Lennard-Jones potential with a strength εpn. We find the critical adsorption point εpn* increases with increasing the active force Fa. The increment of εpn*, denoted as Δεpn*, due to Fa can be expressed approximately as Δεpn* ∝ Fa2.5 for the restricted rotating active polymer (RRAP) where the rotation of the head ABP is restricted and Δεpn* ∝ Fa1.7 for the freely rotating active polymer (FRAP) where the ABP rotates freely. Meanwhile, the conformation of the adsorbed polymer, such as adsorbed trains on NP and the tail near the ABP, are also dependent on Fa. When the tail near the ABP is short, the adsorption is significantly affected by the active force. However, when the tail is long, the whole polymer can be viewed as a long tail stretched by the active force and unperturbed adsorption monomers. Simulation results show that the active force has a direct and significant effect on εpn* and the structure of the adsorbed active polymers.

Dynamics of a two-dimensional active polymer chain with a rotation-restricted active head.

The dynamics of a two-dimensional active polymer composed of an active Brownian particle (ABP) at the head and a passive polymer chain is investigated using Langevin dynamics simulation. The ABP experiences a self-propulsion force fs and a resistance torque M as the passive polymer chain is bonded to the edge of the ABP. M restricts the rotation of the ABP, and thus the dynamics of the ABP and that of the whole active polymer are influenced significantly. Due to this restriction, the persistence time τr, which characterizes the random rotation of the ABP, is increased significantly and changes non-monotonically with the rotational friction coefficient ηr. Our simulation results show that the effect of M on the dynamics of the active polymer can be characterized mainly by the change of τr. Moreover, the propulsive diffusion coefficient DP of the whole polymer chain originated from the self-propulsion force can be described by a scaling relation DP ∝ fs2τr/N2ηt2 with ηt the translational friction coefficient and N the polymer length. Our results show that the diffusion is promoted by the resistance torque M and τr is a key factor for the diffusion of active polymers.

Changes in Bone Mineral Density After Prophylactic Bilateral Salpingo-Oophorectomy in Carriers of a BRCA Mutation.

Importance: Preventive surgery is strongly recommended for individuals with a BRCA mutation at a young age to prevent ovarian cancer and improve overall survival. The overall effect of early surgical menopause on various health outcomes, including bone health, has not been clearly elucidated. Objective: To evaluate the association of prophylactic bilateral salpingo-oophorectomy with bone mineral density (BMD) loss among individuals with a BRCA mutation. Design, Setting, and Participants: This retrospective cohort study of participants with a BRCA mutation who underwent oophorectomy through the University Health Network, Toronto, Ontario, Canada, recruited participants from January 2000 to May 2013. Eligibility criteria included having a BRCA mutation, at least 1 ovary intact prior to surgery, and no history of any cancer other than breast cancer. Bone mineral density was measured using dual-energy x-ray absorptiometry before and after surgery. Data analysis began in December 2018 and finished in January 2019. Main Outcomes and Measures: The annual change in BMD from baseline to follow-up was calculated for the following 3 anatomical locations: (1) lumbar spine, (2) femoral neck, and (3) total hip. Results: A total of 95 women had both a baseline and postsurgery BMD measurement with a mean (SD) follow-up period of 22.0 (12.7) months. The mean (SD) age at oophorectomy was 48.0 (7.4) years. Among women who were premenopausal at time of surgery (50 [53%]), there was a decrease in BMD from baseline to follow-up across the lumbar spine (annual change, -3.45%; 95% CI, -4.61% to -2.29%), femoral neck (annual change, -2.85%; 95% CI, -3.79% to -1.91%), and total hip (annual change, -2.24%; 95% CI, -3.11% to -1.38%). Self-reported hormone therapy use was associated with significantly less bone loss at the lumbar spine (-2.00% vs -4.69%; P = .02) and total hip (-1.38% vs -3.21; P = .04) compared with no hormone therapy use. Among postmenopausal women at time of surgery (45 [47%]), there was also a significant decrease in BMD across the lumbar spine (annual change, -0.82%; 95% CI, -1.42% to -0.23%) and femoral neck (annual change, -0.68%; 95% CI, -1.33% to -0.04%) but not total hip (annual change, -0.18%; 95% CI, -0.82% to 0.46%). Conclusions and Relevance: This study found that oophorectomy was associated with postoperative bone loss, especially among women who were premenopausal at the time of surgery. Targeted management strategies should include routine BMD assessment and hormone therapy use to improve management of bone health in this population.

Novel imaging modalities for the comparison of bone microarchitecture among HIV+ patients with and without fractures: a pilot study.

BACKGROUND: HIV-infected adults have increased fracture risk. OBJECTIVES: To generate pilot data comparing bone density, structure, and strength between HIV-infected adults with and without a prior fracture. METHODS: Adults with and without a prior fracture after their HIV diagnosis were matched 1:1 based on age, sex, race, and smoking history. Participants underwent dual-energy X-ray absorptiometry (DXA), trabecular bone score (TBS), hip structural analyses (HSA), vertebral fracture assessment (VFA), high-resolution peripheral quantitative tomography (HR-pQCT) and measurement of bone turnover markers. Results were compared between cases and controls, with differences expressed as percentages of control group values. RESULTS: 23 pairs were included. On DXA, cases had lower areal bone mineral density (aBMD) at the total hip (median difference in T-score -0.25, p = 0.04), but not the lumbar spine (median difference in T-score 0.10, p = 0.68). Cases had greater abnormalities in HSA and most HR-pQCT and HSA measures, by up to 15%. VFA revealed two subclinical fractures among cases but none among controls. TBS, CTX, and P1NP levels were similar between groups, with differences of 1.9% (p = 0.90), 9.7% (p = 0.55), and 10.0% (p = 0.24), respectively. For each parameter, we report the median and interquartile range for the absolute and relative difference between cases and controls, the correlation between cases and controls, and our recruitment rates, to inform the design of future studies. CONCLUSIONS: These pilot data suggest potential differences in bone structure, estimated bone strength, and asymptomatic vertebral fractures among HIV-infected adults with and without fracture, warranting further study as markers of fracture risk in HIV.

Bone density and structure in healthy postmenopausal women treated with exemestane for the primary prevention of breast cancer: a nested substudy of the MAP.3 randomised controlled trial.

BACKGROUND: Exemestane can prevent breast cancer in postmenopausal women. Because of potential widespread use, we examined the safety of exemestane on bone health. METHODS: In this nested safety substudy of the MAP.3 trial (a randomised, placebo-controlled, double-blind trial of exemestane 25 mg a day for the primary prevention of breast cancer), we included postmenopausal women from five centres who were eligible to participate in MAP.3, not osteoporotic, not receiving drugs for bone-related disorders, with baseline lumbar spine, total hip, and femoral neck T-scores above -2·0. The primary endpoint was percent change from baseline to 2 years in total volumetric bone mineral density (BMD) at the distal radius by high-resolution peripheral quantitative CT. The primary analysis was per protocol using a non-inferiority margin. This analysis was done earlier than originally planned because of the impending announcement of MAP.3 results and subsequent unmasking of patients to treatment assignment. This study is registered with ClinicalTrials.gov, number NCT01144468, and has been extended to 5 years of unmasked follow-up. FINDINGS: 351 women (176 given exemestane, 175 given placebo; median age 61·3 years [IQR 59·2-64·9]) met our inclusion criteria and completed baseline assessment. At the time of clinical cutoff, 242 women had completed 2-year follow-up (124 given exemestane, 118 given placebo). From baseline to 2 years, the mean percent change in total volumetric BMD at the distal radius was -6·1% (95% CI -7·0 to -5·2) in the exemestane group and -1·8% (-2·4 to -1·2) in the placebo group (difference -4·3%, 95% CI -5·3 to -3·2; p<0·0001). The lower limit of the 95% CI was lower than our non-inferiority margin of negative 4% (one-sided test for non-inferiority p=0·70), meaning the hypothesis that exemestane was inferior could not be rejected. At the distal tibia, the mean percent change in total volumetric BMD from baseline to 2 years was -5·0% (95% CI -5·5 to -4·4) in the exemestane group and -1·3% (-1·7 to -1·0) in the placebo group (difference -3·7%, 95% CI -4·3 to -3·0; p<0·0001). The mean percent change in cortical thickness was -7·9% (SD 7·3) in the exemestane group and -1·1% (5·7) in the placebo group at the distal radius (difference -6·8%, 95% CI -8·5 to -5·0; p<0·0001) and -7·6% (SD 5·9) in the exemestane group and -0·7% (4·9) in the placebo group at the distal tibia (difference -6·9%, -8·4 to -5·5; p<0·0001). Decline in areal BMD, as measured by dual-energy x-ray absorptiometry, in the exemestane group compared with the placebo group occurred at the lumbar spine (-2·4% [95% CI -3·1 to -1·7] exemestane vs -0·5% [-1·1 to 0·2] placebo; difference -1·9%, 95% CI -2·9 to -1·0; p<0·0001), total hip (-1·8% [-2·3 to -1·2] exemestane vs -0·6% [-1·1 to -0·1] placebo; difference -1·2%, -1·9 to -0·4; p=0·004), and femoral neck (-2·4% [-3·2 to -1·7] exemestane vs -0·8% [-1·5 to 0·1] placebo; difference -1·6%, -2·7 to -0·6; p=0·002). INTERPRETATION: 2 years of treatment with exemestane worsens age-related bone loss in postmenopausal women despite calcium and vitamin D supplementation. Women considering exemestane for the primary prevention of breast cancer should weigh their individual risks and benefits. For women taking exemestane, regular bone monitoring plus adequate calcium and vitamin D supplementation are important. To assess the effect of our findings on fracture risk, long-term follow-up is needed. FUNDING: Canadian Breast Cancer Research Alliance (Canadian Institutes of Health Research/Canadian Cancer Society).

Effect of 12 months of whole-body vibration therapy on bone density and structure in postmenopausal women: a randomized trial.

BACKGROUND: Although data from studies in animals demonstrated beneficial effects of whole-body vibration (WBV) therapy on bone, clinical trials in postmenopausal women showed conflicting results. OBJECTIVE: To determine whether WBV improves bone density and structure. DESIGN: A 12-month, single-center, superiority, randomized, controlled trial with 3 parallel groups. (ClinicalTrials.gov registration number: NCT00420940) SETTING: Toronto General Hospital, Ontario, Canada. PARTICIPANTS: 202 healthy postmenopausal women with bone mineral density (BMD) T-scores between -1.0 and -2.5 who were not receiving prescription bone medications. INTERVENTION: Participants were randomly assigned to 1 of 3 groups (1:1:1 ratio) by using a block-randomization scheme and sealed envelopes. They were asked to stand on a low-magnitude (0.3g) 90-Hz or 30-Hz WBV platform for 20 minutes daily or to serve as control participants; all participants received calcium and vitamin D. MEASUREMENTS: Bone outcome assessors, who were blinded to group assignment, determined trabecular volumetric BMD and other measurements of the distal tibia and distal radius with high-resolution peripheral quantitative computed tomography and areal BMD with dual-energy x-ray absorptiometry at baseline and at 12 months. RESULTS: 12 months of WBV therapy had no significant effect on any bone outcomes compared with no WBV therapy. For the primary outcome of tibial trabecular volumetric BMD, mean change from baseline was 0.4 mg/cm(3) (95% CI, -0.4 to 1.2 mg/cm(3)) in the 90-Hz WBV group, -0.1 mg/cm(3) (CI, -1.0 to 0.8 mg/cm(3)) in the 30-Hz WBV group, and -0.2 mg/cm(3) (CI, -1.1 to 0.6 mg/cm(3)) in the control group (P = 0.55). Changes in areal BMD at the femoral neck, total hip, and lumbar spine were also similar among the groups. Overall, low-magnitude WBV at both 90 and 30 Hz was well-tolerated. LIMITATIONS: Adherence to WBV ranged from 65% to 79%. Double-blinding was not possible. CONCLUSION: Whole-body vibration therapy at 0.3g and 90 or 30 Hz for 12 months did not alter BMD or bone structure in postmenopausal women who received calcium and vitamin D supplementation.

Vitamin K supplementation in postmenopausal women with osteopenia (ECKO trial): a randomized controlled trial.

BACKGROUND: Vitamin K has been widely promoted as a supplement for decreasing bone loss in postmenopausal women, but the long-term benefits and potential harms are unknown. This study was conducted to determine whether daily high-dose vitamin K1 supplementation safely reduces bone loss, bone turnover, and fractures. METHODS AND FINDINGS: This single-center study was designed as a 2-y randomized, placebo-controlled, double-blind trial, extended for earlier participants for up to an additional 2 y because of interest in long-term safety and fractures. A total of 440 postmenopausal women with osteopenia were randomized to either 5 mg of vitamin K1 or placebo daily. Primary outcomes were changes in BMD at the lumbar spine and total hip at 2 y. Secondary outcomes included changes in BMD at other sites and other time points, bone turnover markers, height, fractures, adverse effects, and health-related quality of life. This study has a power of 90% to detect 3% differences in BMD between the two groups. The women in this study were vitamin D replete, with a mean serum 25-hydroxyvitamin D level of 77 nmol/l at baseline. Over 2 y, BMD decreased by -1.28% and -1.22% (p = 0.84) (difference of -0.06%; 95% confidence interval [CI] -0.67% to 0.54%) at the lumbar spine and -0.69% and -0.88% (p = 0.51) (difference of 0.19%; 95% CI -0.37% to 0.75%) at the total hip in the vitamin K and placebo groups, respectively. There were no significant differences in changes in BMD at any site between the two groups over the 2- to 4-y period. Daily vitamin K1 supplementation increased serum vitamin K1 levels by 10-fold, and decreased the percentage of undercarboxylated osteocalcin and total osteocalcin levels (bone formation marker). However, C-telopeptide levels (bone resorption marker) were not significantly different between the two groups. Fewer women in the vitamin K group had clinical fractures (nine versus 20, p = 0.04) and fewer had cancers (three versus 12, p = 0.02). Vitamin K supplements were well-tolerated over the 4-y period. There were no significant differences in adverse effects or health-related quality of life between the two groups. The study was not powered to examine fractures or cancers, and their numbers were small. CONCLUSIONS: Daily 5 mg of vitamin K1 supplementation for 2 to 4 y does not protect against age-related decline in BMD, but may protect against fractures and cancers in postmenopausal women with osteopenia. More studies are needed to further examine the effect of vitamin K on fractures and cancers. TRIAL REGISTRATION: ClinicalTrials.gov (#NCT00150969) and Current Controlled Trials (#ISRCTN61708241).

Cognitive function, fatigue, and menopausal symptoms in women receiving adjuvant chemotherapy for breast cancer.

PURPOSE: There is evidence that cognitive dysfunction, fatigue, and menopausal symptoms may occur in women receiving adjuvant chemotherapy for breast cancer. Here, we determine their incidence and severity, and interrelationships between them and quality of life. PATIENTS AND METHODS: In this study, 110 women receiving adjuvant chemotherapy each nominated a female relative, friend, or neighbor (matched by age) as a control; 100 eligible matched pairs were evaluated. Patients and controls completed the following assessments: the High-Sensitivity Cognitive Screen, and the Functional Assessment of Cancer Therapy-General (FACT-G) quality of life scale with subscales for fatigue (FACT-F) and endocrine symptoms (FACT-ES). They also performed tests of attention and reaction time. RESULTS: Patients and controls were well matched for age and level of education. There was a higher incidence of moderate or severe cognitive impairment in the patient group (16% v 4%; P =.008). Patients experienced much more fatigue than controls (median FACT-F scores, 31 v 46; P <.0001) and more menopausal symptoms (median FACT-ES scores, 58 v 64; P <.0001). Self-reported quality of life of the patients was poorer than for controls, especially in physical and functional domains (median FACT-G scores, 77 v 93; P <.0001). There was strong correlation between fatigue, menopausal symptoms, and quality of life (P <.0001 for each pair), but none were significantly associated with the presence of cognitive dysfunction. CONCLUSION: Adjuvant chemotherapy causes cognitive dysfunction, fatigue, and menopausal symptoms in women with breast cancer. Priority should be given to the study of strategies that might reduce these toxic effects.