Evaluating the druggability of TrmD, a potential antibacterial target, through design and microbiological profiling of a series of potent TrmD inhibitors.

The post-transcriptional modifier tRNA-(N1G37) methyltransferase (TrmD) has been proposed to be essential for growth in many Gram-negative and Gram-positive pathogens, however previously reported inhibitors show only weak antibacterial activity. In this work, optimisation of fragment hits resulted in compounds with low nanomolar TrmD inhibition incorporating features designed to enhance bacterial permeability and covering a range of physicochemical space. The resulting lack of significant antibacterial activity suggests that whilst TrmD is highly ligandable, its essentiality and druggability are called into question.

Discovery and structure-activity relationships of a novel oxazolidinone class of bacterial type II topoisomerase inhibitors.

There is an increasingly urgent and unmet medical need for novel antibiotic drugs that tackle infections caused by multidrug-resistant (MDR) pathogens. Novel bacterial type II topoisomerase inhibitors (NBTIs) are of high interest due to limited cross-resistance with fluoroquinolones, however analogues with Gram-negative activity often suffer from hERG channel inhibition. A novel series of bicyclic-oxazolidinone inhibitors of bacterial type II topoisomerase were identified which display potent broad-spectrum anti-bacterial activity, including against MDR strains, along with an encouraging in vitro safety profile. In vivo proof of concept was achieved in a A. baumannii mouse thigh infection model.

Restoring carbapenem efficacy: a novel carbapenem companion targeting metallo-ß-lactamases in carbapenem-resistant Enterobacterales.

BACKGROUND: The dissemination of MBLs compromises effective use of many ß-lactams in the treatment of patients with life-threatening bacterial infections. Predicted global increases in the prevalence of MBL-producing carbapenem-resistant Enterobacterales (CRE) are being realized, yielding infections that are untreatable with existing therapies including newly approved ß-lactam/ß-lactamase inhibitor combinations. Developing MBL inhibitors (MBLIs) now is essential to address the growing threat that MBL-producing CRE pose to patients. METHODS: A novel MBLI series was assessed by susceptibility testing and time-kill assays. Target activity and selectivity was evaluated using bacterial NDM, VIM and IMP enzyme assays and human matrix metallopeptidase enzyme assays, respectively, and cytotoxicity was assessed in HepG2 cells. In vivo efficacy of meropenem/MBLI combinations was evaluated in a mouse thigh infection model using an NDM-1-producing Escherichia coli strain. RESULTS: Combination of MBLIs with carbapenems reduced MICs for NDM/IMP/VIM-producing Enterobacterales by up to 128-fold compared with the carbapenems alone. Supplementation of meropenem with the promising compound 272 reduced the MIC90 from 128 to 0.25 mg/L in a panel of MBL-producing CRE clinical isolates (n = 115). Compound 272 restored the bactericidal activity of meropenem and was non-cytotoxic, potentiating the antimicrobial action of meropenem through specific inhibition of NDM, IMP and VIM. In vivo efficacy was achieved in a mouse thigh infection model with meropenem/272 dosed subcutaneously. CONCLUSIONS: We have developed a series of rationally designed MBLIs that restore activity of carbapenems against NDM/IMP/VIM-producing Enterobacterales. This series warrants further development towards a novel combination therapy that combats antibiotic-resistant organisms, which pose a critical threat to human health.

Team-based care Evaluation and Adoption Model (TEAM) Framework: Supporting the comprehensive evaluation of primary care transformation over time.

OBJECTIVE: To introduce the new Team-based care Evaluation and Adoption Model (TEAM) Framework. QUALITY OF EVIDENCE: The initial TEAM Framework was derived from a series of reviews and consultations with academic and clinical experts. In a parallel process, team-based primary and community care evaluation in Canada was assessed through a structured review of academic literature, followed by a review of policy literature of existing primary care evaluation frameworks. MAIN MESSAGE: The review of academic articles alongside an analysis of policy documents and existing evaluation frameworks in primary care resulted in the development of the 10-dimension TEAM Framework. CONCLUSION: Primary care transformation requires evaluation over time. The TEAM Framework provides a comprehensive framework for assessing evidence needed to support short- and long-term actionable improvements for team-based primary and community care in Canada. This framework will inform the development of an evaluation tool kit for primary care teams.

Structural and mechanistic analysis of ATPase inhibitors targeting mycobacterial DNA gyrase.

OBJECTIVES: To evaluate the efficacy of two novel compounds against mycobacteria and determine the molecular basis of their action on DNA gyrase using structural and mechanistic approaches. METHODS: Redx03863 and Redx04739 were tested in antibacterial assays, and also against their target, DNA gyrase, using DNA supercoiling and ATPase assays. X-ray crystallography was used to determine the structure of the gyrase B protein ATPase sub-domain from Mycobacterium smegmatis complexed with the aminocoumarin drug novobiocin, and structures of the same domain from Mycobacterium thermoresistibile complexed with novobiocin, and also with Redx03863. RESULTS: Both compounds, Redx03863 and Redx04739, were active against selected Gram-positive and Gram-negative species, with Redx03863 being the more potent, and Redx04739 showing selectivity against M. smegmatis. Both compounds were potent inhibitors of the supercoiling and ATPase reactions of DNA gyrase, but did not appreciably affect the ATP-independent relaxation reaction. The structure of Redx03863 bound to the gyrase B protein ATPase sub-domain from M. thermoresistibile shows that it binds at a site adjacent to the ATP- and novobiocin-binding sites. We found that most of the mutations that we made in the Redx03863-binding pocket, based on the structure, rendered gyrase inactive. CONCLUSIONS: Redx03863 and Redx04739 inhibit gyrase by preventing the binding of ATP. The fact that the Redx03863-binding pocket is distinct from that of novobiocin, coupled with the lack of activity of resistant mutants, suggests that such compounds could have potential to be further exploited as antibiotics.

Design, synthesis and antibacterial properties of pyrimido[4,5-b]indol-8-amine inhibitors of DNA gyrase.

According to the World Health Organization (WHO), approximately 1.7 million deaths per year are caused by tuberculosis infections. Furthermore, it has been predicted that, by 2050, antibacterial resistance will be the cause of approximately 10 million deaths annually if the issue is not tackled. As a result, novel approaches to treating broad-spectrum bacterial infections are of vital importance. During the course of our wider efforts to discover unique methods of targeting multidrug-resistant (MDR) pathogens, we identified a novel series of amide-linked pyrimido[4,5-b]indol-8-amine inhibitors of bacterial type II topoisomerases. Compounds from the series were highly potent against gram-positive bacteria and mycobacteria, with excellent potency being retained against a panel of relevant Mycobacterium tuberculosis drug-resistant clinical isolates.

Novel Bacterial Topoisomerase Inhibitors with Potent Broad-Spectrum Activity against Drug-Resistant Bacteria.

The novel bacterial topoisomerase inhibitor class is an investigational type of antibacterial inhibitor of DNA gyrase and topoisomerase IV that does not have cross-resistance with the quinolones. Here, we report the evaluation of the in vitro properties of a new series of this type of small molecule. Exemplar compounds selectively and potently inhibited the catalytic activities of Escherichia coli DNA gyrase and topoisomerase IV but did not block the DNA breakage-reunion step. Compounds showed broad-spectrum inhibitory activity against a wide range of Gram-positive and Gram-negative pathogens, including biodefence microorganisms and Mycobacterium tuberculosis No cross-resistance with fluoroquinolone-resistant Staphylococcus aureus and E. coli isolates was observed. Measured MIC90 values were 4 and 8 µg/ml against a panel of contemporary multidrug-resistant isolates of Acinetobacter baumannii and E. coli, respectively. In addition, representative compounds exhibited greater antibacterial potency than the quinolones against obligate anaerobic species. Spontaneous mutation rates were low, with frequencies of resistance typically <10-8 against E. coli and A. baumannii at concentrations equivalent to 4-fold the MIC. Compound-resistant E. coli mutants that were isolated following serial passage were characterized by whole-genome sequencing and carried a single Arg38Leu amino acid substitution in the GyrA subunit of DNA gyrase. Preliminary in vitro safety data indicate that the series shows a promising therapeutic index and potential for low human ether-a-go-go-related gene (hERG) inhibition (50% inhibitory concentration [IC50], >100 µM). In summary, the compounds' distinct mechanism of action relative to the fluoroquinolones, whole-cell potency, low potential for resistance development, and favorable in vitro safety profile warrant their continued investigation as potential broad-spectrum antibacterial agents.

In vitro biological evaluation of novel broad-spectrum isothiazolone inhibitors of bacterial type II topoisomerases.

OBJECTIVES: To evaluate the in vitro biological properties of a novel class of isothiazolone inhibitors of the bacterial type II topoisomerases. METHODS: Inhibition of DNA gyrase and topoisomerase IV activity was assessed using DNA supercoiling and decatenation assays. MIC and MBC were determined according to CLSI guidelines. Antibacterial combinations were assessed using a two-dimensional chequerboard MIC method. Spontaneous frequency of resistance was measured at various multiples of the MIC. Resistant mutants were generated by serial passage at subinhibitory concentrations of antibacterials and genetic mutations were determined through whole genome sequencing. Mammalian cytotoxicity was evaluated using the HepG2 cell line. RESULTS: Representative isothiazolone compound REDX04957 and its enantiomers (REDX05967 and REDX05990) showed broad-spectrum bactericidal activity against the ESKAPE organisms, with the exception of Enterococcus spp., as well as against a variety of other human bacterial pathogens. Compounds retained activity against quinolone-resistant strains harbouring GyrA S83L and D87G mutations (MIC ≤4 mg/L). Compounds inhibited the supercoiling activity of wild-type DNA gyrase and the decatenation function of topoisomerase IV. Frequency of resistance of REDX04957 at 4× MIC was <9.1 × 10(-9). Against a panel of recent MDR isolates, REDX05967 demonstrated activity against Acinetobacter baumannii with MIC50 and MIC90 of 16 and 64 mg/L, respectively. Compounds showed a lack of cytotoxicity against HepG2 cells at 128 mg/L. CONCLUSIONS: Isothiazolone compounds show potent activity against Gram-positive and -negative pathogens with a dual targeting mechanism-of-action and a low potential for resistance development, meriting their continued investigation as broad-spectrum antibacterial agents.

Discovery and structure-activity relationships of a novel isothiazolone class of bacterial type II topoisomerase inhibitors.

There is an urgent and unmet medical need for new antibacterial drugs that tackle infections caused by multidrug-resistant (MDR) pathogens. During the course of our wider efforts to discover and exploit novel mechanism of action antibacterials, we have identified a novel series of isothiazolone based inhibitors of bacterial type II topoisomerase. Compounds from the class displayed excellent activity against both Gram-positive and Gram-negative bacteria with encouraging activity against a panel of MDR clinical Escherichia coli isolates when compared to ciprofloxacin. Representative compounds also displayed a promising in vitro safety profile.

Poly(ε-lysine) dendrons as modulators of quorum sensing in Pseudomonas aeruginosa.

The opportunistic pathogen Pseudomonas aeruginosa is a significant contributor to recalcitrant multi-drug resistant infections. In a vigorous search for alternative therapeutic approaches, the communication system used by this bacterium to synchronise the expression of genes involved in pathogenicity has been identified as a potential target. Poly(ε-lysine) dendrons, composed of three branching generations, were examined herein for their anti-virulence potential and ability to disperse within P. a eruginosa biofilms. These hyperbranched macromolecules reduced attachment and biomass production under different nutrient growth conditions, and at concentrations that were not lethal to planktonic cells (0.2, 0.4 and 0.8 mg/mL). Fluorescent labelling revealed the intracellular localisation and cell-penetrating capacity of the dendron, and showed the rapid uptake and release of unexploited dendron from pre-established P. a eruginosa biofilms. Additionally, the dendron induced complete attenuation of LasA protease, a marker of quorum sensing inactivation, by preventing its accumulation in the external environment. This study thus demonstrates the anti-virulence potential of this class of macromolecules, and could represent a novel therapeutic approach for the treatment of antibiotic-resistant P. a eruginosa infections.

Descriptive analysis and evaluation of Health Link referrals to the emergency department before and during the COVID-19 pandemic.

BACKGROUND: In Alberta, Health Link (HL) provides a 24-h, nurse-staffed, phone resource to the public for health-care advice. HL directs callers to either seek care in the emergency department (ED), with a primary care provider or provide self-care at home. This work aims to describe HL ED referrals prior to and during the COVID-19 pandemic. METHODS: Data from January 1, 2018-December 31, 2019, and July 1, 2020-June 30, 2022, were selected. HL calls were categorized as likely appropriate if the patient was referred and presented to the ED within 24 h and had a Canadian Triage and Acuity Scale (CTAS) of 1-3; or a CTAS of 4-5 and the patient was admitted, specialist consulted, or diagnostic imaging or laboratory tests were completed. The primary outcome was the percentage of likely appropriate referrals among all HL ED referrals. RESULTS: In the 2018-2019 and 2020-2022 samples, respectively, there were 845,372 and 832,730 calls. Of the 211,723 and 213,486 ED referrals, only 140,614 (66.4%) and 143,322 (67.1%) presented to an ED. Of these, 84.3 and 86.7 per 100 patient visits were categorized as likely appropriate referrals. Health Link referrals account for 3.2% and 3.8% of all ED visits. IMPACT: HL referrals to the ED represent only a small percentage of all ED visits. Based on our definition, most referrals by HL are likely appropriate. The COVID-19 pandemic does not appear to have altered the rates of calls to HL, the number of HL calls referred to the ED, nor the likely appropriateness of those referrals.

Learnings from Racialized Adolescents and Young Adults with Lived Experiences of Cancer: "It's Okay to Critique the System That Claims to Save Us".

Interest in AYA cancer care has increased globally over the recent past; however, most of this work disproportionately represents white, heterosexual, middle-income, educated, and able-bodied people. There is recognition in the literature that cancer care systems are not structured nor designed to adequately serve people of colour or other equity-denied groups, and the structural racism in the system prevents prevention, treatment, and delivery of care. This work seeks to examine structural racism and the ways that it permeates into the lived experiences of AYAs in their cancer care. This article represents the first phase of an 18-month, patient-oriented, Participatory Action Research project focused on cancer care for racialized AYAs that is situated within a broader program of research focused on transforming cancer care for AYAs. Semi-structured interviews were completed with 18 AYAs who self-identify as racialized, have lived experiences with cancer, and have received treatment in Canada. Following participant review of their transcripts, the transcripts were de-identified, and then coded by three separate authors. Five main themes were identified using thematic analysis, including the need to feel supported through experiences with (in)fertility, be heard and not dismissed, advocate for self and have others advocate for you, be in community, and resist compliance.

Impact of Health Link utilization on emergency department visits.

OBJECTIVES: Our aim was to compare Health Link utilization in urban and rural Alberta by metrics relevant to the ED. METHODS: Data on Health Link callers from January 1, 2018-December 31, 2019 was extracted from the National Ambulatory Care Reporting System, including postal code, location of ED attended, Canadian Triage Acuity Scale (CTAS) assigned at ED, age, and self-identified gender. Usage density (presentations/100/year), patient demographics (age, self-identified gender), and ED metrics (CTAS, investigations, admission) were compared for Health Link ED referrals and direct ED visits. RESULTS: In this period, 900,196 individuals called Health Link, 241,103 were referred to the ED, 58% (140,614) of which presented to the ED within 24 h of their call. These referrals constituted 3.4% of the total ED visit population (4,194,735). Looking at the density of ED utilization, this is greater in rural than urban settings with respect to patients who present directly to the ED (90.9 vs. 36.5 presentations/100/year). There is a sparser density of Health Link ED visits in rural settings than in urban centres (1.5 vs. 1.6). Urban ED presentations were more often triaged as a CTAS 1-3 than a CTAS 4-5 if they had presented after a Health Link referral (76.0% CTAS 1-3) than a direct ED visit (63.0% CTAS 1-3). This effect is greater for rural patients, who also more likely to present as a CTAS 1-3 than a CTAS 4-5 if they were referred through Health Link (61.1% CTAS 1-3) compared to those who directly went to the ED (39.0% CTAS 1-3). CONCLUSIONS: This study on Health Link describes how tele-health can often triage higher acuity patients to appropriately receive ED level care, which may be important for future development of health care and ED infrastructure.

RéSUMé: OBJECTIFS: Notre objectif était de comparer l'utilisation de Health Link dans les zones urbaines et rurales de l'Alberta en fonction de paramètres pertinents pour l'urgence. MéTHODES: Les données sur les appelants de Health Link du 1er janvier 2018 au 31 décembre 2019 ont été extraites du Système national d'information sur les soins ambulatoires, y compris le code postal, le lieu de l'urgence fréquentée, l'échelle canadienne de triage et de gravité (ETG) attribuée à l'urgence, l'âge et le sexe auto-identifié. La densité d'utilisation (présentations/100/an), les caractéristiques démographiques des patients (âge, sexe déclaré) et les paramètres des urgences (ETG, investigations, admission) ont été comparés pour les orientations vers les urgences de Health Link et les visites directes aux urgences. RéSULTATS: Au cours de cette période, 900 196 personnes ont appelé Health Link, 241 103 ont été dirigées vers les urgences, dont 58 % (140 614) se sont présentées aux urgences dans les 24 heures suivant leur appel. Ces renvois représentaient 3,4 % du nombre total de visites aux urgences (4 194 735). La densité d'utilisation des urgences est plus élevée dans les zones rurales que dans les zones urbaines en ce qui concerne les patients qui se présentent directement aux urgences (90,9 contre 36,5 présentations/100/an). La densité des visites aux urgences de Health Link est plus faible dans les zones rurales que dans les centres urbains (1,5 contre 1,6). Les patients qui se présentaient aux urgences en milieu urbain étaient plus souvent classés dans l'ETG 1-3 que dans l'ETG 4-5 s'ils avaient été orientés par Health Link (76,0 % ETG 1-3) que s'ils s'étaient rendus directement aux urgences (63,0 % ETG 1-3). Cet effet est plus important pour les patients des zones rurales, qui sont également plus susceptibles de présenter un ÉTG 1-3 qu'un ÉTG 4-5 s'ils ont été orientés par Health Link (61,1 % d'ÉTG 1-3) que s'ils se sont rendus directement aux urgences (39,0 % d'ÉTG 1-3). CONCLUSIONS: Cette étude sur Health Link décrit comment la télésanté permet souvent de trier les patients les plus graves pour qu'ils reçoivent les soins appropriés au niveau des urgences, ce qui peut être important pour le développement futur des infrastructures de soins de santé et des urgences.

Evaluation of Homogentisic Acid, a Prospective Antibacterial Agent Highlighted by the Suitability of Nitisinone in Alkaptonuria 2 (SONIA 2) Clinical Trial.

Despite urgent warnings about the spread of multidrug-resistant bacteria, the antibiotic development pipeline has remained sparsely populated. Naturally occurring antibacterial compounds may provide novel chemical starting points for antibiotic development programs and should be actively sought out. Evaluation of homogentisic acid (HGA), an intermediate in the tyrosine degradation pathway, showed that the compound had innate activity against Gram-positive and Gram-negative bacteria, which was lost following conversion into the degradation product benzoquinone acetic acid (BQA). Anti-staphylococcal activity of HGA can be attributed to effects on bacterial membranes. Despite an absence of haemolytic activity, the compound was cytotoxic to human HepG2 cells. We conclude that the antibacterial activity and in vitro safety profile of HGA render it more suitable for use as a topical agent or for inclusion in a small-molecule medicinal chemistry program.

Access to episodic primary care: a cross-sectional comparison of walk-in clinics and urgent primary care centers in British Columbia.

AIM: This study aimed to identify publicly reported access characteristics for episodic primary care in BC and provided a clinic-level comparison between walk-in clinics and UPCCs. BACKGROUND: Walk-in clinics are non-hospital-based primary care facilities that are designed to operate without appointments and provide increased healthcare access with extended hours. Urgent and Primary Care Centres (UPCCs) were introduced to British Columbia (BC) in 2018 as an additional primary care resource that provided urgent, but not emergent care during extended hours. METHODS: This cross-sectional study used publicly available data from all walk-in clinics and UPCCs in BC. A structured data collection form was used to record access characteristics from clinic websites, including business hours, weekend availability, attachment to a longitudinal family practice, and provision of virtual services. FINDINGS: In total, 268 clinics were included in the analysis (243 walk-in clinics, 25 UPCCs). Of those, 225 walk-in clinics (92.6%) and two UPCCs (8.0%) were attached to a longitudinal family practice. Only 153 (63%) walk-in clinics offered weekend services, compared to 24 (96%) of UPCCs. Walk-in clinics offered the majority (8,968.6/ 78.4%) of their service hours between 08:00 and 17:00, Monday to Friday. UPCCs offered the majority (889.3/ 53.7%) of their service hours after 17:00. CONCLUSION: Most walk-in clinics were associated with a longitudinal family practice and provided the majority of clinic services during typical business hours. More research that includes patient characteristics and care outcomes, analyzed at the clinic level, may be useful to support the optimization of episodic primary healthcare delivery.

Finding Primary Care-Repurposing Physician Registration Data to Generate a Regionally Accurate List of Primary Care Clinics: Development and Validation of an Open-Source Algorithm.

BACKGROUND: Some Canadians have limited access to longitudinal primary care, despite its known advantages for population health. Current initiatives to transform primary care aim to increase access to team-based primary care clinics. However, many regions lack a reliable method to enumerate clinics, limiting estimates of clinical capacity and ongoing access gaps. A region-based complete clinic list is needed to effectively describe clinic characteristics and to compare primary care outcomes at the clinic level. OBJECTIVE: The objective of this study is to show how publicly available data sources, including the provincial physician license registry, can be used to generate a verifiable, region-wide list of primary care clinics in British Columbia, Canada, using a process named the Clinic List Algorithm (CLA). METHODS: The CLA has 10 steps: (1) collect data sets, (2) develop clinic inclusion and exclusion criteria, (3) process data sets, (4) consolidate data sets, (5) transform from list of physicians to initial list of clinics, (6) add additional metadata, (7) create working lists, (8) verify working lists, (9) consolidate working lists, and (10) adjust processing steps based on learnings. RESULTS: The College of Physicians and Surgeons of British Columbia Registry contained 13,726 physicians, at 2915 unique addresses, 6942 (50.58%) of whom were family physicians (FPs) licensed to practice in British Columbia. The CLA identified 1239 addresses where primary care was delivered by 4262 (61.39%) FPs. Of the included addresses, 84.50% (n=1047) were in urban locations, and there was a median of 2 (IQR 2-4, range 1-23) FPs at each unique address. CONCLUSIONS: The CLA provides a region-wide description of primary care clinics that improves on simple counts of primary care providers or self-report lists. It identifies the number and location of primary care clinics and excludes primary care providers who are likely not providing community-based primary care. Such information may be useful for estimates of capacity of primary care, as well as for policy planning and research in regions engaged in primary care evaluation or transformation.

Effects of sex and exercise training on ß-adrenoreceptor-mediated opposition of evoked sympathetic vasoconstriction in resting and contracting muscle of rats.

This study investigated the hypothesis that ß-adrenoreceptor-mediated inhibition of sympathetic vasoconstriction would be enhanced in female compared with male rats, and that endurance exercise training would augment ß-adrenoreceptor-mediated inhibition of sympathetic vasoconstriction in male and female rats. Sprague-Dawley rats were randomized into sedentary (male: n = 7; female: n = 8) and exercise-trained (male: n = 9; female: n = 9) groups. Following 4 wk of exercise training or being sedentary, rats were anesthetized and surgically instrumented for stimulation of the lumbar sympathetic chain, muscle contraction and measurement of arterial blood pressure and femoral artery blood flow (FBF). Femoral vascular conductance (FVC) was calculated as FBF/mean arterial pressure. The percentage change of FVC in response to sympathetic stimulation delivered at 2 and 5 Hz was measured at rest and during contraction of the triceps surae muscles before and after ß-adrenoreceptor blockade (propranolol: 0.075 mg·kg-1 iv). We found that, at rest, ß-adrenoreceptor blockade decreased (main effect of drug, 2 Hz: P < 0.001; 5 Hz: P < 0.001) sympathetic vasoconstriction. During contraction, sympathetic vasoconstrictor responsiveness was lower (main effect of sex, 2 Hz: P = 0.001; 5 Hz: P = 0.023) in female compared with male rats, and sympatholysis was enhanced (main effect of sex, 2 Hz: P = 0.001; 5 Hz: P < 0.001) in female rats. ß-adrenoreceptor blockade decreased (main effect of drug, 2 Hz: P = 0.049; 5 Hz: P < 0.001) evoked sympathetic vasoconstriction in contracting muscle. The present study demonstrated that ß-adrenoreceptors do not blunt sympathetic vasoconstriction in resting or contracting skeletal muscle of male or female rats. Sympatholysis was enhanced in female rats; however, this was not attributable to ß-adrenoreceptor-mediated blunting of sympathetic vasoconstriction.NEW & NOTEWORTHY ß-adrenoreceptors do not inhibit sympathetic vasoconstriction in resting or contracting muscle of male or female rats, regardless of training status. Sympatholysis was enhanced in female, compared to male rats; however, ß-adrenoreceptors were not responsible for the enhanced sympatholysis. These findings indicate that ß-adrenoreceptors do not contribute to the regulation of sympathetic vasoconstriction in resting and contracting skeletal muscle and suggest that ß-adrenoreceptors do not underlie sex differences in the neural control of the circulation.

Antimicrobial Properties of Gallium(III)- and Iron(III)-Loaded Polysaccharides Affecting the Growth of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, In Vitro.

Antimicrobial resistance (AMR) has become a global concern as many bacterial species have developed resistance to commonly prescribed antibiotics, making them ineffective to treatments. One type of antibiotics, gallium(III) compounds, stands out as possible candidates due to their unique "Trojan horse" mechanism to tackle bacterial growth, by substituting iron(III) in the metabolic cycles of bacteria. In this study, we tested three polysaccharides (carboxymethyl cellulose (CMC), alginate, and pectin) as the binding and delivery agent for gallium on three bacteria (Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus) with a potential bioresponsive delivery mode. Two types of analysis on bacterial growth (minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC)) were carried out while iron(III)-loaded polysaccharide samples were also tested for comparison. The results suggested that gallium showed an improved inhibitory activity on bacterial growth, in particular gallium(III)-loaded carboxymethyl cellulose (Ga-CMC) sample showing an inhibiting effect on growth for all three tested bacteria. At the MIC for all three bacteria, Ga-CMC showed no cytotoxicity effect on human dermal neonatal fibroblasts (HDNF). Therefore, these bioresponsive gallium(III) polysaccharide compounds show significant potential to be developed as the next-generation antibacterial agents with controlled release capability.

ß-Adrenoreceptors do not oppose sympathetic vasoconstriction in resting and contracting skeletal muscle of male rats.

Sympathetic nervous system (SNS) vasoconstriction is primarily achieved through the binding of norepinephrine (NE) to α-adrenoreceptors. However, NE may also bind to ß-adrenoreceptors and cause vasodilation that may oppose/blunt SNS-mediated vasoconstriction. Therefore, this study investigated the hypothesis that ß-adrenoreceptor-mediated vasodilation opposes evoked vasoconstriction in resting and contracting skeletal muscle. Male (n = 9) Sprague-Dawley rats were anesthetized and surgically instrumented for stimulation of the lumbar sympathetic chain and measurement of arterial blood pressure and femoral artery blood flow. The percentage change of femoral vascular conductance in response to sympathetic chain stimulation delivered at 2 and 5 Hz was determined at rest and during triceps surae skeletal muscle contraction before (control) and after ß-adrenoreceptor blockade (propranolol; 0.075 mg·kg-1, intravenously). ß-Adrenoreceptor blockade did not alter (P > 0.05) baseline hemodynamics or the hyperemic response to exercise. At the 2 Hz stimulation frequency, sympathetic vasoconstriction was similar (P > 0.05) in control and ß-blockade conditions in resting (control, -34% ± 6%; ß-blockade, -33% ± 8%) and contracting (control, -16% ± 6%; ß-blockade, -14% ± 7%) muscle. At the 5 Hz stimulation frequency, sympathetic vasoconstrictor responsiveness was reduced (main effect of drug, P < 0.05) following ß-blockade (rest: control, -52% ± 7%; ß-blockade, -51% ± 9%; contraction: control, -32% ± 11%; ß-blockade, -29% ± 13%). Novelty These data indicate that ß-adrenoreceptor blockade did not augment sympathetic vasoconstriction at rest or during exercise. The study demonstrates that ß-adrenoreceptors do not oppose evoked sympathetic vasoconstriction in resting or contracting skeletal muscle or contribute to functional sympatholysis.