High time resolution measurements of droplet evaporation kinetics and particle crystallisation.

A refined technique for observing the complete evaporation behaviour of free-falling droplets, from droplet generation to complete solvent evaporation, with ultra-high time resolution is introduced and benchmarked. High-resolution phase-delay stroboscopic imaging is employed to simultaneously resolve the evolving droplet morphology, geometric and aerodynamic diameters, throughout the evaporative lifetime with a user-controlled < µs timescale. This allows rapid, complex morphological changes, such as crystallisation events, to be clearly observed and the corresponding mechanisms to be inferred. The dried particles are sampled for offline SEM analysis and the observed morphologies compared to the inflight imaging. Density changes can be calculated directly from the deviation between the geometric and aerodynamic diameters. The full capabilities of the new technique are demonstrated by examination of the different evaporation behaviours and crystallisation mechanisms for aqueous sodium chloride droplets evaporating under different ambient relative humidity (RH) conditions. The crystallisation window, defined as the time taken from initial to complete crystallisation, is shown to be RH dependent, extending from 0.03 s at 20% RH and 0.13 s at 40% RH. The different crystallisation mechanisms observed during the experiments are also clearly reflected in the final structure of the dry particles, with multi-crystal structures produced at low RH compared to single-crystal structures at higher RH. It is anticipated that this technique will unlock measurements which explore the evaporation behaviour and crystallisation mechanisms for rapid, complex droplet drying events, and with increasingly non-ideal solutions, relevant to industrial applications.

Modelling the effect of first-wave COVID-19 on mental health services.

During the first wave of the COVID-19 pandemic it emerged that the nature and magnitude of demand for mental health services was changing. Considerable increases were expected to follow initial lulls as treatment was sought for new and existing conditions following relaxation of 'lockdown' measures. For this to be managed by the various services that constitute a mental health system, it would be necessary to complement such projections with assessments of capacity, in order to understand the propagation of demand and the value of any consequent mitigations. This paper provides an account of exploratory modelling undertaken within a major UK healthcare system during the first wave of the pandemic, when actionable insights were in short supply and decisions were made under much uncertainty. In understanding the impact on post-lockdown operational performance, the objective was to evaluate the efficacy of two considered interventions against a baseline 'do nothing' scenario. In doing so, a versatile and purpose-built discrete time simulation model was developed, calibrated and used by a multi-disciplinary project working group. The solution, representing a multi-node, multi-server queueing network with reneging, is implemented in open-source software and is freely and publicly available.

Step by step: reconstruction of terrestrial animal movement paths by dead-reckoning.

BACKGROUND: Research on wild animal ecology is increasingly employing GPS telemetry in order to determine animal movement. However, GPS systems record position intermittently, providing no information on latent position or track tortuosity. High frequency GPS have high power requirements, which necessitates large batteries (often effectively precluding their use on small animals) or reduced deployment duration. Dead-reckoning is an alternative approach which has the potential to 'fill in the gaps' between less resolute forms of telemetry without incurring the power costs. However, although this method has been used in aquatic environments, no explicit demonstration of terrestrial dead-reckoning has been presented. RESULTS: We perform a simple validation experiment to assess the rate of error accumulation in terrestrial dead-reckoning. In addition, examples of successful implementation of dead-reckoning are given using data from the domestic dog Canus lupus, horse Equus ferus, cow Bos taurus and wild badger Meles meles. CONCLUSIONS: This study documents how terrestrial dead-reckoning can be undertaken, describing derivation of heading from tri-axial accelerometer and tri-axial magnetometer data, correction for hard and soft iron distortions on the magnetometer output, and presenting a novel correction procedure to marry dead-reckoned paths to ground-truthed positions. This study is the first explicit demonstration of terrestrial dead-reckoning, which provides a workable method of deriving the paths of animals on a step-by-step scale. The wider implications of this method for the understanding of animal movement ecology are discussed.

A new approach to determine vapour pressures and hygroscopicities of aqueous aerosols containing semi-volatile organic compounds.

We present a new approach to study the equilibrium gas-particle partitioning of volatile and semi-volatile organic components in aqueous aerosol, deriving a correlational analysis method that examines and interprets simultaneous and correlated fluctuations in particle size and composition. From this approach, changes in particle size driven by organic component evaporation can be clearly resolved from size changes driven by hygroscopicity and fluctuations in environmental conditions. The approach is used to interpret measurements of the evaporation of semi-volatile organic components from binary aqueous/organic aerosol and the hygroscopic growth of involatile inorganic aerosol. The measurements have been made by the aerosol optical tweezers technique, which allows the simultaneous retrieval of particle size and refractive index with high accuracy. We suggest that this approach will be particularly valuable for investigating the thermodynamic behaviour of mixed component aqueous aerosol and will allow the accurate derivation of solution phase equilibrium properties that are prone to large uncertainties when measurements are made simply of the change in particle size with gas phase relative humidity.

Effects of a PEGylated soluble TNF receptor type 1 (PEG sTNF-RI) on cytokine expression in adjuvant arthritis.

OBJECTIVE: To investigate the effects of TNF blocking therapy on synovial immune activity in rat adjuvant arthritis (AA) by measuring mRNA expression of key macrophage and T cell cytokines during PEG sTNF-RI treatment (10mg/kg) on days 8, 10 and 12. METHODS: Paw volume was assessed every 3-4 days. Ankles were removed for quantitative radiology and histology and synovial membrane removed to determine cytokine mRNA expression using semi-quantitative RT-PCR. T cells in joints were quantified by immunohistochemistry. RESULTS: Paw volume was significantly decreased in rats treated with PEG STNF-RI from days 12 to 17. Histology scores and synovial T cell numbers were reduced on days 13 and 17 and radiology scores significantly reduced on day 13. Expression of synovial TNF, IFN-gamma, IL-17, IL-2 and IL-4 mRNA was unchanged in treated rats and TGF-beta expression was significantly increased at day 13. CONCLUSIONS: PEG sTNF-RI attenuates AA and disease recurs after treatment ceases, similar to human rheumatoid arthritis. Continued TNF production and/or ongoing T cell activity, may explain the recrudescence of disease once treatment is stopped.

The in vivo effects of tumour necrosis factor blockade on the early cell mediated immune events and syndrome expression in rat adjuvant arthritis.

Anti-TNF therapy is effective in rheumatoid arthritis (RA); however, its mechanisms of action are incompletely understood. T cell-driven mechanisms are thought to play an important role in RA and the effects of TNF blockade on these mechanisms are unclear. Adjuvant arthritis (AA) is a T cell dependent model of inflammatory arthritis. The aims of this study were to investigate the effects of TNF blockade on in vivo T cell cytokine expression and to clarify the role of TNF in the inguinal lymph nodes (ILN) in early arthritis. AA was induced in male DA rats. Rats received either 3 mg/kg or 10 mg/kg PEG sTNF-RI at days 0, 2 and 4 postinduction or 10 mg/kg anti-TNF antibody on day of arthritis induction. Control rats received either saline or normal sheep serum. Paw volume was assessed every 3-4 days. Rats were sacrificed on days 0, 6, 13 and 21 postinduction. Ankles were removed for quantitative radiology and histology. Synovium and ILN were removed for cell culture and to determine mRNA expression of cytokines using semiquantitative RT-PCR. TNF and IFN-gamma protein production was measured using a bioassay and an ELISA. TNF blockade did not suppress mRNA expression of T cell cytokines in the ILN of rats in the early phase of AA, suggesting ongoing T cell activity. TNF protein production by ILN cells in culture was reduced in PEG sTNF-RI treated rats, although mRNA expression was increased in the ILN prior to culture. Early administration of PEG sTNF-RI did not attenuate AA, in contrast to an anti-TNF antibody, which suppressed disease. A shorter half-life for the PEG sTNF-RI compared with the anti-TNF antibody or the development of anti-PEG sTNF-RI antibodies may account for these results.

The kappa-opioid agonist, asimadoline, alters cytokine gene expression in adjuvant arthritis.

OBJECTIVE: We have previously found that the kappa-opioid agonist, asimadoline, attenuates adjuvant arthritis in a dose-dependent, antagonist-reversible manner. To elucidate possible mechanisms, we investigated the effects of asimadoline (5 mg/kg/day i.p.) or vehicle on in vivo cytokine expression and T-cell recruitment in adjuvant arthritis. METHODS: Arthritis severity was assessed every 3-4 days for 21 days. Rats were killed on days 0, 13 and 21 post-induction and synovial membrane and inguinal lymph nodes were removed for mRNA extraction. Changes in cytokine mRNA expression were measured using reverse transcription-polymerase chain reaction (RT-PCR) and densitometry. T cells in joints were quantified by immunohistochemistry. RESULTS: Asimadoline significantly decreased arthritis severity at day 13, with a concomitant decrease in synovial membrane expression of cytokines interleukin-17 and transforming growth factor-beta (TGF-beta) mRNA at day 13, and no change in T cell numbers in the joints of arthritic rats. By contrast, in the inguinal lymph nodes, expression of tumour necrosis factor was increased at day 13 and TGF-beta mRNA was increased throughout. CONCLUSION: An altered balance, therefore, in the pro- and anti-inflammatory effects of TGF-beta by asimadoline might explain its striking anti-arthritic actions.

Effects of nitric oxide synthase inhibition on ciliary blood flow, aqueous production and intraocular pressure.

A prior study found that inhibition of nitric oxide synthase with L-NAME causes a large, rapid decrease in IOP in anesthetized rabbits. In this follow-up study we sought to determine if this hypotensive effect was due to decreased aqueous production, possibly caused by ciliary vasoconstriction. Two protocols were performed in anesthetized rabbits. In the first protocol, mean arterial pressure (MAP) and IOP were measured by direct cannulation, and aqueous flow was measured by fluorophotometry, before and after L-NAME (5 mg kg(-1), i.v., n = 7). In the second protocol, ciliary blood flow was measured transclerally by laser Doppler flowmetry while MAP was varied mechanically over a wide range before and after L-NAME (5 mg kg(-1), i.v., n = 8). L-NAME caused a significant increase in MAP and decreases in IOP, ciliary blood flow and aqueous flow. L-NAME also caused a significant downward shift in the ciliary pressure-flow relation over the entire pressure range examined. The results indicate that L-NAME causes ciliary vasoconstriction and decreases aqueous production, suggesting that the L-NAME ocular hypotensive effect may be due in part to a blood flow-dependent decrease in aqueous production. However, assuming no uveoscleral outflow and constant episcleral venous pressure and outflow facility, the decrease in aqueous flow accounts for 66% of the drop in IOP, suggesting an additional effect of L-NAME on aqueous outflow.

Urinary ascariasis in a man with hematuria.

We present a case believed to be the first reported North American presentation of Ascaris lumbricoides within the urogenital tract. A young man came to the emergency department because of painless hematuria and having observed a 6-inch worm exit his urethra while urinating. The most common site for A lumbricoides infection is the gastrointestinal tract, specifically the area of the hepatopancreatic ducts. Worldwide, A lumbricoides infections are ubiquitous, but infections outside the alimentary tract are extremely rare.

Cytokine expression and synovial pathology in the initiation and spontaneous resolution phases of adjuvant arthritis: interleukin-17 expression is upregulated in early disease.

The aim of this study was to understand the immune processes controlling the initiation and spontaneous resolution of adjuvant arthritis (AA). We investigated synovial T-cell recruitment and mRNA expression of IL-17 and other important disease related cytokines, IFN-gamma, IL-2, IL-4, TNF and TGF-beta in inguinal lymph node (ILN) and synovial membrane (SM). Arthritis severity was assessed by a numerical rating score and rats were sacrificed every 3--4 days postadjuvant induction. Further assessment involved quantitative radiology and histology of the ankle joints on each day, and the ILN and SM were removed for RNA extraction. Cytokine mRNA expression was measured using RT-PCR and densitometry. Paraffin sections of rat ankle joints were stained for T-cells (CD3) by immunohistochemistry. In the ILN, there was an increase in IL-17, TNF and IFN-gamma expression in the early stages of disease, with a secondary sustained increase in IFN-gamma expression. In the SM, there was expression of T-cell cytokines in early arthritis (day 13), and prolonged TNF and TGF-beta expression, which reflected disease progression. IL-4 mRNA expression increased in the later stages of AA. Synovial T-cell numbers transiently increased at day 6, and remained high from days 13--28. Increased pro-inflammatory cytokine expression, including IL-17, in the ILN reflects the initiating events in the early stage of disease. IL-17 may therefore play an important role in the pathogenesis of AA. The increase in IL-4 (an anti-inflammatory cytokine) in the SM in the later stages of AA suggests that IL-4 is involved in the spontaneous resolution of AA. The initial increase in IFN-gamma in the ILN may reflect a pro-inflammatory response, while the prolonged secondary increase may indicate activation of regulatory T-cells.

Effects of the peripherally selective kappa-opioid asimadoline, on substance P and CGRP mRNA expression in chronic arthritis of the rat.

We have previously shown that the kappa-opioid agonist, asimadoline, produces time-dependent changes in neuropeptide concentrations in the joints of rats with chronic arthritis. We hypothesized that asimadoline acts on peripheral terminals to modulate substance P (SP) release. To address this hypothesis, here we have examined neuropeptide expression in their source cells in dorsal root ganglia (DRG) that innervate the joint, as well as in non-neuronal tissue, after treatment with asimadoline. We found an increased production of SP and CGRP in untreated chronic arthritic animals which supports our previous finding of increased SP content in the joint. More importantly, the kappa-opioid asimadoline reduced the expression of both SP and calcitonin gene-related peptide-alpha (alpha-CGRP) in DRG cells but had no effect on the very low expression of neuropeptides in non-neuronal tissue. The fact that SP synthesis is attenuated by asimadoline accords with our hypothesis that the increased tissue levels of SP result from kappa-mediated pre-synaptic inhibition of release leading to augmented tissue stores. These in vivo data confirm literature findings that opioids inhibit SP release from peripheral endings of primary afferent fibres.

A dilution immunoassay to measure myosin regulatory light chain phosphorylation.

We examined the quantitation of myosin regulatory light chain phosphorylation (MRLCP) by Western blot and found both offset and saturation errors. The desirable characteristics of an MRLCP assay are that the dynamic range be 60- to 100-fold and that the detection threshold be known and preferably very small relative to total MRLC concentration. No technique examined provided all these characteristics. However, accurate measurements can be obtained by including serial dilutions of the sample to provide a fractional calibration scale in terms of the dephosphorylated light chain and by using interpolation of the phosphorylated band signal intensity to provide values for the relative phosphorylation ratio. We found that this method offers several advantages over methods that rely on signal ratios from single samples: The dilution ratio method is less subject to errors from differences in protein load, it offers estimates of the error in the individual measurement, and has some redundancy that increases the likelihood of obtaining a valid measurement despite gel or membrane artifacts.

The importance of the hypothalamo-hypophyseal-adrenal axis to the anti-inflammatory actions of the kappa-opioid agonist PNU-50,488H in rats with adjuvant arthritis.

Possible contributions of the hypothalamo-hypophyseal-adrenal axis to the development of adjuvant-induced arthritis and therapeutic actions of the prototypical kappa-opioid agonist PNU-50,488H (PNU-50) were studied in DA rats. Paw edema, nociception, histological and radiological joint damage, and tumor necrosis factor-alpha release by peritoneal macrophages were measured in adrenalectomized (ADX) and sham-operated (SHO) arthritic animals (drug-treated and untreated groups). Disease developed earlier in ADX rats (paw edema was first apparent 11 days postadjuvant compared with day 13 in SHO animals) and remained more severe in that group. Twice-daily PNU-50 treatment completely prevented the development of edema in the SHO group but was effective in the ADX animals only on day 18. PNU-50 substantially reduced the pooled severity index (combined quantitative edema, histological and radiological assessments) at day 18 in both SHO and ADX rats and to an equal extent. During disease development, the paws of SHO, but not ADX, rats became hyperalgesic; paradoxically, ADX animals were hyperalgesic during PNU-50 treatment, but the drug produced analgesia in SHO animals. Compared with cells harvested from healthy animals, macrophages from arthritic rats released about twice as much tumor necrosis factor-alpha after lipopolysaccharide stimulation. It was concluded that the hypothalamo-hypophyseal-adrenal axis influences the development of adjuvant arthritis and plays a partial role in the therapeutic action of the kappa-agonist PNU-50.

Hyperalgesia due to nerve injury: role of prostaglandins.

The hypothesis that prostaglandins contribute to hyperalgesia resulting from nerve injury was tested in rats in which the sciatic nerve was partially transected on one side. Subcutaneous injection of indomethacin (a classic inhibitor of cyclo-oxygenase) into the affected hindpaw relieved mechanical hyperalgesia for up to 10 days after injection. Subcutaneous injection of meloxicam or SC-58125 (selective inhibitors of cyclo-oxygenase-2) into the affected hindpaw also relieved mechanical hyperalgesia, but with a shorter time-course. Subcutaneous injection of SC-19220 (an EP1 prostaglandin receptor blocker) into the affected hindpaw produced significant relief of mechanical and thermal hyperalgesia. Comparable injections into the contralateral paw or abdomen had no effect on mechanical or thermal hyperalgesia, suggesting that the effects we observed were local rather than systemic. We conclude that prostaglandins, probably prostaglandin E1 or E2, contribute to the peripheral mechanisms underlying hyperalgesia following nerve injury. These data provide further evidence that inflammatory mediators contribute to neuropathic pain, and may warrant further study of peripherally administered non-steroidal anti-inflammatory drugs as a possible treatment for such pain in patients.

Zinc alleviates thermal hyperalgesia due to partial nerve injury.

Zinc has recently been shown to alleviate inflammatory hyperalgesia. In the present study, we showed that intrathecal, intraplantar or systemic injection of zinc chloride significantly relieved thermal hyperalgesia in rats with sciatic nerve injury. Alleviation of thermal hyperalgesia was dose dependent in each case, although higher doses were required for i.p. injections (ED50 = 13.6 nmole) than for intrathecal (ED50 = 0.05 nmole) or intraplantar injections (ED50 = 0.3 nmole). Neither intrathecal nor intraplantar zinc chloride influenced thermal nociception in normal rats without nerve injury. The results provide the first evidence that zinc alleviates neuropathic hyperalgesia.

Involvement of substance P in the anti-inflammatory effects of the peripherally selective kappa-opioid asimadoline and the NK1 antagonist GR205171.

We have previously shown that kappa-opioids have antiarthritic properties. In this study, using two differently acting drugs (the peripherally selective kappa-agonist, asimadoline, and the NK1-antagonist, GR205171), we have examined possible roles of the neuropeptide substance P (SP) in the pathogenesis and maintenance of experimental arthritis in rats. The anti-inflammatory actions and the time dependence of these drugs were compared, and concentrations of SP determined in joint tissue. In untreated animals, SP levels in ankle joint tissue increased late in the disease (by day 21) but substantially lagged behind development of clinical disease. Prolonged (days 1-21 or days 12-18) but not early, short-term (days 1-3) treatment with the NK1-antagonist GR205171 (1 mg/kg/day i.p.) significantly attenuated joint damage; SP levels showed multiphasic dose dependence over the 21-day treatment. The data suggest that GR205171 antagonizes the action of SP by presynaptic as well as postsynaptic mechanisms. Treatment with asimadoline (5 mg/kg/day i.p. ) produced marked (and sustained) attenuation of the disease with all three time regimes. The effect of asimadoline on SP levels was time dependent: reduction of SP content after 3 days but an increase after 12 or 21 days treatment, paradoxically with clinical improvement in each case. Drug-induced changes in SP content could follow from changed release or synthesis from either neural or immune cells. The results suggest that both drugs have potential therapeutic value at different stages of inflammatory joint disease.

Zinc alleviates thermal hyperalgesia due to partial nerve injury.

Zinc has recently been shown to alleviate inflammatory hyperalgesia. In the present study, we showed that intrathecal, intraplantar or systemic injection of zinc chloride significantly relieved thermal hyperalgesia in rats with sciatic nerve injury. Alleviation of thermal hyperalgesia was dose dependent in each case, although higher doses were required for i.p. injections (ED50 = 13.6 nmol) than for intrathecal (ED50 = 0.05 nmol) or intraplantar injections (ED = 0.3 nmol). Neither intrathecal nor intraplantar zinc chloride influenced thermal nociception in normal rats without nerve injury. The results provide the first evidence that zinc alleviates neuropathic hyperalgesia.

Gender differences in pain.

A literature survey reveals clear evidence of sex differences in the incidence of painful conditions and their severity, both being greater in women. The possible causes of this sexual dimorphism are discussed. Sex-role stereotyping may be relevant and there is evidence to indicate that, perhaps through their roles as carers, women seek and utilize more medical services than men. Less clear-cut evidence for anatomical and physiological differences is reviewed, together with documentation of hormonal (and reproductive cycle) influences on the operation of those systems.

Effect of the peripherally selective kappa-opioid agonist, asimadoline, on adjuvant arthritis.

1. Opioids, though widely used as analgesics, have not been seriously considered as therapy for rheumatoid arthritis. The present study evaluated the dose-effect and time-dependence relationships of a new peripherally selective kappa agonist, asimadoline, in rats with adjuvant arthritis. 2. The arthritis was assessed by a pooled severity index combining the comprehensive criteria of oedema, radiography and histological changes, in the hind limbs. Asimadoline was extremely effective in attenuating joint damage (by up to 80%) when administered parenterally (0.5 to 10 mg kg(-1) day(-1), i.p.) throughout the disease or during its early phase; treatment was less successful if confined to the latter stages. Ten fold higher doses were effective orally. 3. Equimolar doses of a peripherally-selective antagonist, naloxone methiodide, and the kappa-selective antagonist, MR2266, fully reversed the peripheral anti-arthritic effects of asimadoline (5 mg kg(-1) day(-1)), indicating that asimadoline acts through peripheral kappa-opioid receptors. However, an equivalent dose of MR2266 did not fully reverse the anti-arthritic effects of the highest dose of asimadoline (40 mg kg(-1) day(-1)), suggesting a loss of kappa-selectivity at this dose. 4. Asimadoline also exhibited analgesic effects (mechanical nociceptive thresholds) in arthritic but not non-arthritic rats, indicating that inflammation is necessary for asimadoline-induced analgesia. 5. These data confirm our previous findings that kappa-opioids possess anti-arthritic properties and that these effects are mediated via peripheral kappa-receptors. The present results are new in showing that the peripherally acting kappa-opioid agonist, asimadoline, is a potent anti-arthritic agent. Such novel drugs, essentially lacking central side effects, herald new treatments for rheumatoid arthritis.