The experiences of podiatrists prescribing custom foot orthoses and patients using custom foot orthoses for foot pain management in the United Kingdom: A focus group study.

INTRODUCTION: Foot pain can be a significant burden for patients. Custom foot orthoses (CFOs) have been a mainstay in podiatry treatment for foot pain management and improving foot function. However, little is known about podiatrists' experience of prescribing CFOs or patient experience of using foot orthoses (FOs), including CFOs, for foot pain. METHODS: A focus group (FG) discussion with three FOs users (Female = 2 and Male = 1) was conducted in November 2022 within a private podiatry practice. This group represented non-experts from the general local population of individuals with existing or previous foot pain who have personally experienced using either over-the-counter FOs or CFOs. An online FG discussion with five musculoskeletal (MSK) specialist podiatrists (Female = 2 and Male = 3) was also conducted in December 2022. This group represented podiatrists with specialist knowledge in foot biomechanics and clinical experience in CFO provision. The FG discussions were recorded and lasted 49 and 57 min respectively. Transcribed data was manually coded, and a thematic analysis was undertaken to identify patterns within the collected data. RESULTS: The participants in the patient FG detailed mixed experiences of the prescription process and CFOs received, with reports of limited involvement/input in their prescription, the need for frequent adjustments and high costs. The impact on footwear choices, replicability and transferability of CFOs into different types of shoes and technologies to aid design were also highlighted. In the podiatrist FG, lack of confidence in design and manufacture processes, prescription form language, relationship and communication building with manufacturers, variability in the CFOs issued and the need for better student education in CFO provision emerged as key themes. CONCLUSION: Patients and podiatrists shared similar views on CFO provision, namely poor communication with manufacturers leading to dissatisfaction with the CFOs prescribed causing negative impacts on patient experiences. Podiatrists called for greater education at registration level to increase new graduate podiatrist knowledge in CFO design and manufacture and better collaboration with manufacturing companies.

Access to Chronic Pain Services for Adults from Minority Ethnic Groups in the United Kingdom (UK): a Scoping Review.

BACKGROUND: Chronic pain services in the UK are required to provide services which meet the diverse needs of patients, but little is known about the access and use of these services by minority ethnic groups. OBJECTIVE: To assess the available evidence regarding the ethnic profile of adults who access secondary and tertiary chronic pain services in the UK. METHODS: A scoping review was conducted (August 2021-October 2021), comprising comprehensive literature searches using Embase, Medline and CINAHL databases and the grey literature. Studies were included if they reported on (i) access to chronic pain services in secondary and/or tertiary care in the UK, (ii) adults and (iii) stated the ethnicity of the involved participants. Studies were included if published between 2004 and 2021, as demographic data during this period would be broadly representative of the UK population, as per the 2021 UK census. A descriptive synthesis of the extracted data was performed. RESULTS: The search yielded 124 records after duplicates were removed. Following title and abstract screening, 44 full texts were screened, ten of which were included in the review. CONCLUSIONS: This is the first review to explore access to chronic pain services for adults from minority ethnic groups in the UK. Given the limited number of studies that met the inclusion criteria, the review highlights the need for routine collection of ethnicity data using consistent ethnic categories within UK chronic pain services and increased involvement of minority ethnic groups within chronic pain research. Findings should inform future research that aims to improve access to UK chronic pain services for adults from minority ethnic groups.

TTA-P2 is a potent and selective blocker of T-type calcium channels in rat sensory neurons and a novel antinociceptive agent.

Several agents that are preferential T-type calcium (T-channel) blockers have shown promise as being effective in alleviating acute and chronic pain, suggesting an urgent need to identify even more selective and potent T-channel antagonists. We used small, acutely dissociated dorsal root ganglion (DRG) cells of adult rats to study the in vitro effects of 3,5-dichloro-N-[1-(2,2-dimethyl-tetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide (TTA-P2), a derivative of 4-aminomethyl-4-fluoropiperdine, on T currents, as well as other currents known to modulate pain transmission. We found that TTA-P2 potently and reversibly blocked DRG T currents with an IC(50) of 100 nM and stabilized channel in the inactive state, whereas high-voltage-activated calcium and sodium currents were 100- to 1000-fold less sensitive to channel blocking effects. In in vivo studies, we found that intraperitoneal injections of 5 or 7.5 mg/kg TTA-P2 reduced pain responses in mice in phases 1 and 2 of the formalin test. Furthermore, TTA-P2, at 10 mg/kg i.p., selectively and completely reversed thermal hyperalgesia in diabetic rats treated with streptozocin but had no effect on the nociceptive response of healthy animals. The antihyperalgesic effects of TTA-P2 in diabetic rats were completely abolished by administration of oligonucleotide antisense for Ca(V)3.2 isoform of T channels. Thus, TTA-P2 is not only the most potent and selective blocker of T channels in sensory neurons yet described, but it also demonstrates the potential for the pharmacological effectiveness of this approach in addressing altered nociceptive responses in animal models of both inflammatory and neuropathic pain.

Free radical signalling underlies inhibition of CaV3.2 T-type calcium channels by nitrous oxide in the pain pathway.

Nitrous oxide (N2O, laughing gas) has been used as an anaesthetic and analgesic for almost two centuries, but its cellular targets remain unclear. Here, we present a molecular mechanism of nitrous oxide's selective inhibition of CaV3.2 low-voltage-activated (T-type) calcium channels in pain pathways. Using site-directed mutagenesis and metal chelators such as diethylenetriamine pentaacetic acid and deferoxamine, we reveal that a unique histidine at position 191 of CaV3.2 participates in a critical metal binding site, which may in turn interact with N2O to produce reactive oxygen species (ROS). These free radicals are then likely to oxidize H191 of CaV3.2 in a localized metal-catalysed oxidation reaction. Evidence of hydrogen peroxide and free radical intermediates is given in that N2O inhibition of CaV3.2 channels is attenuated when H2O2 is neutralized by catalase. We also use the adrenochrome test as an indicator of ROS in vitro in the presence of N2O and iron. Ensuing in vivo studies indicate that mice lacking CaV3.2 channels display decreased analgesia to N2O in response to formalin-induced inflammatory pain. Furthermore, a superoxide dismutase and catalase mimetic, EUK-134, diminished pain responses to formalin in wild-type mice, but EUK-134 and N2O analgesia were not additive. This suggests that reduced ROS levels led to decreased inflammation, but without the presence of ROS, N2O was not able to provide additional analgesia. These findings reveal a novel mechanism of interaction between N2O and ion channels, furthering our understanding of this widely used analgesic in pain processing.

The NapF protein of the Escherichia coli periplasmic nitrate reductase system: demonstration of a cytoplasmic location and interaction with the catalytic subunit, NapA.

The periplasmic nitrate reductase of Escherichia coli is important during anaerobic growth in low-nitrate environments. The nap operon encoding this nitrate reductase comprises seven genes including a gene, napF, that encodes a putative cytoplasmic iron-sulphur protein of uncertain subcellular location and function. In this study, N-terminal sequence analysis, cell fractionation coupled with immunoblotting and construction of LacZ and PhoA fusion proteins were used together to establish that NapF is located in the E. coli cytoplasm. A bacterial two-hybrid protein-protein interaction system was used to demonstrate that NapF interacted in the cytoplasm with the terminal oxidoreductase NapA, but that it did not self-associate or interact with other electron-transport components of the Nap system, NapC, NapG or NapH, or with another cytoplasmic component, NapD. NapF, purified as a His(6)-tagged protein, exhibited spectral properties characteristic of an iron-sulphur protein. This protein was able to pull down NapA from soluble extracts of E. coli. A growth-based assay for NapF function in intact cell cultures was developed and applied to assess the effect of mutation of a number of conserved amino acids. It emerged that neither a highly conserved N-terminal double-arginine motif, nor a conserved proline motif, is essential for NapF-dependent growth. The combined data indicate that NapF plays one or more currently unidentified roles in the post-translational modification of NapA prior to the export of folded NapA via the twin-arginine translocation pathway into the periplasm.

Properties of the periplasmic nitrate reductases from Paracoccus pantotrophus and Escherichia coli after growth in tungsten-supplemented media.

Paracoccus pantotrophus grown anaerobically under denitrifying conditions expressed similar levels of the periplasmic nitrate reductase (NAP) when cultured in molybdate- or tungstate-containing media. A native PAGE gel stained for nitrate reductase activity revealed that only NapA from molybdate-grown cells displayed readily detectable nitrate reductase activity. Further kinetic analysis showed that the periplasmic fraction from cells grown on molybdate (3 microM) reduced nitrate at a rate of V(max)=3.41+/-0.16 micromol [NO(3)(-)] min(-1) mg(-1) with an affinity for nitrate of K(m)=0.24+/-0.05 mM and was heat-stable up to 50 degrees C. In contrast, the periplasmic fraction obtained from cells cultured in media supplemented with tungstate (100 microM) reduced nitrate at a much slower rate, with much lower affinity (V(max)=0.05+/-0.002 micromol [NO(3)(-)] min(-1) mg(-1) and K(m)=3.91+/-0.45 mM) and was labile during prolonged incubation at >20 degrees C. Nitrate-dependent growth of Escherichia coli strains expressing only nitrate reductase A was inhibited by sub-mM concentrations of tungstate in the medium. In contrast, a strain expressing only NAP was only partially inhibited by 10 mM tungstate. However, none of the above experimental approaches revealed evidence that tungsten could replace molybdenum at the active site of E. coli NapA. The combined data show that tungsten can function at the active site of some, but not all, molybdoenzymes from mesophilic bacteria.

Respiratory detoxification of nitric oxide by the cytochrome c nitrite reductase of Escherichia coli.

Nitric oxide is a key element in host defense against invasive pathogens. The periplasmic cytochrome c nitrite reductase (NrfA) of Escherichia coli catalyzes the respiratory reduction of nitrite, but in vitro studies have shown that it can also reduce nitric oxide. The physiological significance of the latter reaction in vivo has never been assessed. In this study the reduction of nitric oxide by Escherichia coli was measured in strains active or deficient in periplasmic nitrite reduction. Nrf(+) cells, harvested from cultures grown anaerobically, possessed a nitric-oxide reductase activity with physiological electron donation of 60 nmol min(-1) x mg dry wt(-1), and an in vivo turnover number of NrfA of 390 NO* s(-1) was calculated. Nitric-oxide reductase activity could not be detected in Nrf(-) strains. Comparison of the anaerobic growth of Nrf(+) and Nrf(-) strains revealed a higher sensitivity to nitric oxide in the NrfA(-) strains. A higher sensitivity to the nitrosating agent S-nitroso-N-acetyl penicillamine (SNAP) was also observed in agar plate disk-diffusion assays. Oxygen respiration by E. coli was also more sensitive to nitric oxide in the Nrf(-) strains compared with the Nrf(+) parent strain. The results demonstrate that active periplasmic cytochrome c nitrite reductase can confer the capacity for nitric oxide reduction and detoxification on E. coli. Genomic analysis of many pathogenic enteric bacteria reveals the presence of nrf genes. The present study raises the possibility that this reflects an important role for the cytochrome c nitrite reductase in nitric oxide management in oxygen-limited environments.