Tenofovir Douche as HIV Preexposure Prophylaxis for Receptive Anal Intercourse: Safety, Acceptability, Pharmacokinetics, and Pharmacodynamics (DREAM 01)

BACKGROUND

Despite highly effective HIV preexposure prophylaxis (PrEP) options, no options provide on-demand, nonsystemic, behaviorally congruent PrEP that many desire. A tenofovir-medicated rectal douche before receptive anal intercourse may provide this option.

METHODS

Three tenofovir rectal douches-220 mg iso-osmolar product A, 660 mg iso-osmolar product B, and 660 mg hypo-osmolar product C-were studied in 21 HIV-negative men who have sex with men. We sampled blood and colorectal tissue to assess safety, acceptability, pharmacokinetics, and pharmacodynamics.

RESULTS

The douches had high acceptability without toxicity. Median plasma tenofovir peak concentrations for all products were several-fold below trough concentrations associated with oral tenofovir disoproxil fumarate (TDF). Median colon tissue mucosal mononuclear cell (MMC) tenofovir-diphosphate concentrations exceeded target concentrations from 1 hour through 3 to 7 days after dosing. For 6-7 days after a single product C dose, MMC tenofovir-diphosphate exceeded concentrations expected with steady-state oral TDF 300 mg on-demand 2-1-1 dosing. Compared to predrug baseline, HIV replication after ex vivo colon tissue HIV challenge demonstrated a concentration-response relationship with 1.9 log10 maximal effect.

CONCLUSIONS

All 3 tenofovir douches achieved tissue tenofovir-diphosphate concentrations and colorectal antiviral effect exceeding oral TDF and with lower systemic tenofovir. Tenofovir douches may provide a single-dose, on-demand, behaviorally congruent PrEP option, and warrant continued development. Clinical Trials Registration . NCT02750540.

Digitally Recording Comfort Observations in the Last Days of Life

Background: 37.5% of deaths in our area occur in hospital. There are known high unmet needs of adult patients dying in hospital, this unmet need can be reduced by using an individualised care plan and specialist palliative care review. Intervention: In 2022 UHSussex developed an electronic comfort observation chart and individualised care plan, with a centralised dashboard allowing Palliative Care Teams (SPCT) to view trends, target interventions, and a rolling prospective audit. Results: 3000 patients have had their care supported with electronic comfort observations (e-comfort obs). Over 72% of all deaths in the Trust in the last 3 months have been on e-comfort obs, with 2/3 of all deaths in the first 12 months on e-comfort obs. The average length of time on e-comfort obs is 4 days resulting in 70,000 sets of e-comfort obs recorded since launch. Seven percent of e-comfort obs record moderate or severe symptoms. We have identified benefits to people who are dying, those important to them, ward staff, SPCT and on a systems level. Conclusion: E-comfort obs can be successfully embedded in a large acute Trust. This development should improve quality of end of life care in our hospitals both for individuals and for future patients, through on-going targeted education and intervention. Further work is needed to develop the system further including integrating data from electronic prescribing.

Development of a radiographic technique for porcine head ballistic research

INTRODUCTION

The porcine model shows structural features comparable to that of humans and are routinely used within research, due to the ethical, legal, and practical use of post-mortem human samples. Methods for obtaining high quality and comparable reference data using standardised acquisition protocols are essential.

METHODS

The decapitated heads of three adult white sows were subjected to radiographic imaging before and after cranial trauma (9 mm, Heckler and Koch MP5). Digital radiographs were generated using a Siemens MULTIX TOP system with an Agfa digital detector, with foam blocks and sandbags as ancillary equipment. An iterative approach was adopted by the authors to generate reproducible radiographic views from two perpendicular angles. Specimens were kept at 5 °C and wrapped in polythene bags to reduce the impact of putrefaction.

RESULTS

Standardised head radiography technique was developed for superior-inferior and lateral views demonstrating porcine anatomy. Key parameters included: automatic exposure control for tube current (∼4 mAs), tube voltage of 73 kVp, 100 cm source to image receptor distance, and an anti-scatter grid. Slight variances in specimen morphology, developmental status, and soft tissue changes did not affect imaging outcomes.

CONCLUSION

The technique and positioning proposed in this study allows for the acquisition of high quality and reproducible radiographic images for comparable ballistic research datasets. Specimen positioning and centring of the primary beam may be applied across porcine breeds, although individual radiographic parameters may differ according to equipment specifications and specimen size.

IMPLICATIONS FOR PRACTICE

Development of a reproducible radiographic technique of porcine heads in forensic and veterinary research.

Can retrospectively fusing SPECT to CT images reduce radiation doses in myocardial perfusion imaging?

INTRODUCTION

To establish if the CT dataset acquired during the stress element of myocardial perfusion imaging can be fused to the subsequent rest scan to reduce radiation doses from these procedures.

METHODS

86 rest scans were processed and evaluated using a self-designed project specific tool. Recording processing time, the time between the two data sets selected for fusion and assessing radiographic reports to ensure produced images were of diagnostic quality.

RESULTS

70% of fused scans were acquired 6-7 days apart; the mean (SD) processing time was calculated as 2.03 (0.36) minutes. The Pearson's correlation between these two variables was determined to be 0.22, showing a slight positive correlation although not statistically significant. 100% of the images produced were of diagnostic quality.

CONCLUSION

Rest scans can be fused to a previously acquired CT, careful consideration should be given when positioning the patient and to the time interval between acquiring the two data sets, departmental guidelines can assist with this. Staff training may also be beneficial to ensure staff can assess if data sets are fusible prior to completing a scan.

IMPLICATIONS FOR PRACTICE

This data provides evidence that retrospective fusion can reduce patient radiation doses in myocardial perfusion imaging without compromising diagnostic outcomes. Dose optimisation is an essential part of the ionising radiation (medical exposure) regulations therefore retrospective fusion should be considered in practice to ensure departmental compliance, although it is noteworthy this study is solely based in a single centred one camera department.

Short Communication: Identification of equine corticotropin-like intermediate lobe peptide (CLIP) binding to an adrenocortipcotrophic hormone (ACTH) assay capture antibody

A chemiluminescent immunoassay is commonly employed to measure adrenocorticotrophic hormone (ACTH) concentrations to assist pituitary pars intermedia dysfunction diagnosis. In a previous study, seasonally-dependent assay cross-reactivity to endogenous equine corticotropin-like intermediate lobe peptide (CLIP, ACTH 18-39) was suspected. The present study aimed to demonstrate binding of endogenous equine CLIP to the capture antibody of the ACTH chemiluminescent immunoassay. Liquid chromatography - mass spectrometry (LCMS) methods were optimised to identify selected ions from synthetic human ACTH, α-melanocyte stimulating hormone (α-MSH, ACTH 1-17) and CLIP. Synthetic ACTH and CLIP bound to the capture antibody of the chemiluminescent ACTH assay, but α-MSH did not. Equine endogenous CLIP was detected by LCMS in pony plasma taken in the autumn and could be eluted from the capture antibody of the ACTH chemiluminescent immunoassay. Further research is required to enable quantification of CLIP. Equine CLIP may alter measured ACTH concentrations in vivo.

Gut dysbiosis and inflammatory blood markers precede HIV with limited changes after early seroconversion

BACKGROUND

Alterations in the gut microbiome have been associated with HIV infection, but the relative impact of HIV versus other factors on the gut microbiome has been difficult to determine in cross-sectional studies.

METHODS

To address this, we examined the gut microbiome, serum metabolome, and cytokines longitudinally within 27 individuals before and during acute HIV using samples collected from several ongoing cohort studies. Matched control participants (n=28) from the same cohort studies without HIV but at similar behavioral risk were used for comparison.

FINDINGS

We identified few changes in the microbiome during acute HIV infection, but did find alterations in serum metabolites involving secondary bile acid (lithocholate sulfate, glycocholenate sulfate) and amino acid metabolism (3-methyl-2-oxovalerate, serine, cysteine, N-acetylputrescine). Greater microbiome differences, including decreased Bacteroides spp and increased Megasphaera elsdenii, were seen when comparing pre-HIV infection visits to matched at-risk controls. Those who acquired HIV also had elevated inflammatory cytokines (TNF-α, B cell activating factor, IL-8) and bioactive lipids (palmitoyl-sphingosine-phosphoethanolamide and glycerophosphoinositol) prior to HIV acquisition compared to matched controls.

INTERPRETATION

Longitudinal sampling identified pre-existing microbiome differences in participants with acute HIV compared to matched control participants observed over the same period. These data highlight the importance of increasing understanding of the role of the microbiome in HIV susceptibility.

FUNDING

This work was supported by NIH/NIAID (K08AI124979; P30AI117943), NIH/NIDA (U01DA036267; U01DA036939; U01DA036926; U24DA044554), and NIH/NIMH (P30MH058107; R34MH105272).

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Delivering evidence-based interventions for type 1 diabetes in the virtual world - A review of UK practice during the SARS-CoV-2 pandemic

AIMS

This review considers the impact of the SARS-CoV-2 pandemic on access to interventions for those living with type 1 diabetes and discusses the solutions which have been considered and actioned to ensure ongoing access care.

METHODS

We performed a focussed review of the published literature, and the guidelines for changes that have been effected during the pandemic. We also drew from expert recommendations and information about local practice changes for areas where formal data have not been published.

RESULTS

Evidence based interventions which support the achievement of improved glucose levels and/or reduction in hypoglycaemia include group structured education to support self-management, insulin pump therapy and continuous glucose monitoring. The SARS-CoV-2 pandemic had impacted the ability of diabetes services to deliver these intervention. Multiple adaptations have been put in place - transition to online delivery of education and care, and usage of diabetes technology.

CONCLUSIONS

Although various adaptations have been made during the pandemic that have positively influenced uptake of services, there are many areas of delivery that need immediate improvement in the UK. We recommend a proactive approach in recognising the digital divide and inequity in distribution of these changes and we recommend introducing measures to reduce them.

Radiography of human dry bones: A reflective account with recommendations for practice

INTRODUCTION

This study presents the reflective account of a large-scale radiographic survey of medieval and post-medieval long bones from St Albans, United Kingdom. As a practicing diagnostic radiographer and archaeologist, the author sought to apply experiential learning to generate recommendations for archaeological and forensic radiography practice. The purpose of the imaging was to identify Harris lines for biological stress, however this reflective piece concerns the adaptation of clinical radiographic technique for human dry bones.

METHODS

Imaging took place over five sessions in early 2021 with the assistance of an osteoarchaeologist. Radiography followed standard clinical views (anterior-posterior and medio-lateral) of femora, humeri, radii and tibiae using a digital radiography system. A workplace diary was used to record challenges, solutions and musings related to radiographic technique. The Rolfe, Freshwater and Jasper reflective model was applied to collate and present findings.

RESULTS

A total of 502 radiographs of 426 long bones (92 individuals) were acquired. A multidisciplinary team was found to be essential for correct identification of anatomy, laterality and orientation of remains during the survey. Anterior-posterior views were easiest to achieve, with medio-lateral imaging requiring considerably more effort. Radiolucent sponge supports were necessary, although fragmented remains were often impossible to position accurately. Hands-on experience of human bones improved the author's knowledge and confidence with osteology.

CONCLUSION

Although limited to selective long bones of archaeological context and personal experience, the findings of this study have direct applications for forensic radiography practice. This includes use of a multidisciplinary team, robust workflow with integrated failsafe checks, consistent imaging approach and the application of radiolucent sponge supports.

IMPLICATIONS FOR PRACTICE

Recommendations within this study may contribute towards a comprehensive guide for radiographic technique for human dry bones.

Feasibility of using his bundle pacing with boston scientific generators

Introduction

His bundle pacing (HBP) aims to deliver physiological activation of the ventricles via the native His-Purkinje conduction system. A challenge of HBP is the limited market of implantation tools, pacing leads and specifically designed pacing algorithms.

Purpose

Over the last three years both Medtronic (MDT) and Boston Scientific (BSC) generators have been used for HBP in a large tertiary centre. We examined whether there was any difference between lead parameters and battery longevity depending on the type of manufacturer used.

Methods

Patients implanted with a MDT Select Secure model 3830 lead were included in this retrospective study. Data collected included HBP thresholds (analysed at 1ms pulse width) at implant and at the most recent device check, HBP percentages and battery longevity (months). Battery longevity were calculated by adding duration of follow up and estimated battery life at last follow up.

Results

A total of 31 patients were included for data analysis (58% male and mean age 72 years). 18 patients had MDT generators of which 3 were PPMs, 5 were CRT-Ps and 10 were CRT-Ds. 13 patients had BSC generators of which 5 were PPMs, 5 were CRT-Ps and 3 were CRT-Ds. Mean follow up of the cohort was 12.7±9.02 months.

Mean HBP percentages were 77±37% and 72.2±42.1% for MDT and BSC, respectively (p=0.430). Mean HBP threshold (Volts) at implant was significantly lower with BSC vs MDT (0.85±0.58 vs 1.84±1.06, p=0.01), and similar after follow up (1.01±0.91 vs 1.32±0.73, p=NS). There were no statistically significant differences between mean HBP threshold at implant compared to follow up for both manufacturers.

Interestingly, mean battery longevity for BSC vs MDT generators was significantly higher (136±29.3 vs 90.5±29.1, p<0.001). Longevity was also compared for PPM/CRT-P and CRT-D separately. For PPM/CRT-P, BSC generators had significantly higher longevity as compared to MDT (141.6±33.1 vs 91.6±34.5, p=0.009). This difference was not observed for CRT-Ds between the 2 manufacturers (p=0.068).

Conclusion

Our results suggest HBP with MDT Select Secure 3830 lead is feasible with BSC generators. There is potentially greater battery longevity with BSC compared to MDT generators. Further studies are needed with greater numbers and longer follow up to confirm this finding.

Funding Acknowledgement

Type of funding sources: None.

32 Congenital Arteriovenous Malformation of The Breast Associated with Giant Hairy Naevus: A Case Report

Introduction

An arteriovenous malformation (AVM) is defined as an abnormal connection between arteries and veins, bypassing the capillary system. AVM of the breast is a rare clinical entity, with limited evidence to guide management. We present the case of a congenital AVM of the breast in an otherwise healthy woman, with an interesting presenting complaint.

Case Description

A 38-year-old female presented with a ‘buzzing’ sensation and mastalgia in her left breast. Examination revealed a visible pulsatile linear abnormality with a bruit on auscultation. Duplex ultrasonography demonstrated mixing of the arterial and venous flow, consistent with an AVM. Operative management entailed ultrasound guided identification, ligation and excision of all aneurysmal segments. Histopathologic evaluation demonstrated an AVM with no malignant features. At one year postoperatively, the patient reported complete symptom resolution. Literature review identified nine case reports, including two cases of congenital breast AVM, both treated surgically. Seven cases of iatrogenic AVM were identified, with diagnosis based on duplex ultrasonography and management by surgical ligation in all except one, which resolved spontaneously.

Conclusions

ongenital AVM of the breast is a rare clinical entity. Diagnosis can be established using duplex ultrasonography, while CT and MRI may be useful for preoperative planning. Endovascular management alone is associated with high recurrence rates and surgical excision is the favoured approach where technically feasible without major aesthetic or functional compromise.

Primary, Recall, and Decay Kinetics of SARS-CoV-2 Vaccine Antibody Responses

Studies of two SARS-CoV-2 mRNA vaccines suggested that they yield ∼95% protection from symptomatic infection at least short-term, but important clinical questions remain. It is unclear how vaccine-induced antibody levels quantitatively compare to the wide spectrum induced by natural SARS-CoV-2 infection. Vaccine response kinetics and magnitudes in persons with prior COVID-19 compared to virus-naı̈ve persons are not well-defined. The relative stability of vaccine-induced versus infection-induced antibody levels is unclear. We addressed these issues with longitudinal assessments of vaccinees with and without prior SARS-CoV-2 infection using quantitative enzyme-linked immunosorbent assay (ELISA) of anti-RBD antibodies. SARS-CoV-2-naı̈ve individuals achieved levels similar to mild natural infection after the first vaccination; a second dose generated levels approaching severe natural infection. In persons with prior COVID-19, one dose boosted levels to the high end of severe natural infection even in those who never had robust responses from infection, increasing no further after the second dose. Antiviral neutralizing assessments using a spike-pseudovirus assay revealed that virus-naı̈ve vaccinees did not develop physiologic neutralizing potency until the second dose, while previously infected persons exhibited maximal neutralization after one dose. Finally, antibodies from vaccination waned similarly to natural infection, resulting in an average of ∼90% loss within 90 days. In summary, our findings suggest that two doses are important for quantity and quality of humoral immunity in SARS-CoV-2-naı̈ve persons, while a single dose has maximal effects in those with past infection. Antibodies from vaccination wane with kinetics very similar to that seen after mild natural infection; booster vaccinations will likely be required.

The use of ondansetron for the treatment of nausea in dogs with vestibular syndrome

Background

Vestibular syndrome is often accompanied by nausea. Drugs currently approved for its treatment have been developed to stop vomiting but not nausea. The efficacy of 5-HT₃ receptor antagonists to reduce nausea has been described for chemotherapy, but not for nausea secondary to vestibular disorders.

Methods

Sixteen dogs with vestibular syndrome-associated nausea were included in the open-label, multicentre study. The intensity of nausea-like behaviour was analysed before ondansetron administration (0.5 mg/kg i.v.) and 2 h afterwards, using a validated 5-point-scale. The occurrence and frequency of salivation, lip licking, restlessness, vocalisation, lethargy, and vomiting were assessed.

Results

All dogs initially showed signs of nausea, whereas only 31% showed vomitus. The intensity of nausea was significantly reduced in all dogs (p ≤ 0.0001) 2 h after ondansetron administration, including the clinical signs of nausea analysed in 11 dogs (salivation [p = 0.0078], lip licking [p = 0.0078], restlessness [p = 0.0039], and lethargy [p = 0.0078]) except for vocalisation (p > 0.9999).

Conclusions

The results provide preliminary evidence of the potential benefit of ondansetron in the treatment of nausea, which was present in all examined dogs. Vomiting was only observed in 5 dogs indicating that nausea can occur separately and should not be perceived only as a preceding stimulation of the vomiting centre.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02931-9.

Brief Report: HIV-1 Seroconversion Is Not Associated With Prolonged Rectal Mucosal Inflammation

OBJECTIVE

Determine the impact of HIV-1 seroconversion on inflammatory cytokines in the rectal mucosa.

SETTING

Secondary analysis of data from men who have sex with men and transgender women who participated in a HIV prevention trial Lima, Peru.

METHODS

From July to December 2017, 605 men who have sex with men and transgender women were screened for rectal gonorrhea/chlamydia (GC/CT). Fifty GC/CT-positive cases were randomly selected and matched with 52 GC/CT-negative controls by age and number of receptive anal intercourse partners in the last month. All participants were HIV-negative at baseline and those with GC/CT at baseline and/or follow-up received appropriate antibiotic therapy. Participants underwent sponge collection of rectal secretions for the measurement of inflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α) and were screened for rectal GC/CT and HIV at baseline, 3 months, and 6 months. Wilcoxon rank-sum tests compared inflammatory cytokine levels between participants diagnosed with HIV during follow-up and persons who remained HIV-negative.

RESULTS

Eight participants were diagnosed with HIV at the 3-month (n = 6) or 6-month (n = 2) visit. The median number of receptive anal intercourse partners in the month before HIV diagnosis was the same for those who acquired HIV and those who did not. There were no significant differences in inflammatory cytokine levels in rectal mucosa between participants who did and did not experience HIV seroconversion at any time point.

CONCLUSIONS

Despite a surge in viral replication during acute infection, findings from this study suggest that there is no prolonged effect of HIV-1 seroconversion on inflammatory cytokine levels in the rectal mucosa.

The effect of myxomatous mitral valve disease severity on packed cell volume in dogs

OBJECTIVES

The aim of this study was to examine whether associations between disease severity and packed cell volume exist in dogs with myxomatous mitral valve disease.

MATERIALS AND METHODS

Data were selected from 289 dogs that had been examined at a research clinic (2004-2017) on multiple occasions (n=1465). American College of Veterinary Internal Medicine stage and echocardiographic measurements were entered in separate multivariable linear mixed effects models with packed cell volume as the dependent variable. Age, breed, sex, weight and blood urea nitrogen concentrations were additionally tested in these analyses to control for patient characteristics.

RESULTS

Packed cell volume (% whole blood) in stages B1 and B2 (B1: 42.62 ±0.27, P=0.001; B2: 41.77± 0.42, P < 0.001) was lower than stage A (44.57 ±0.53). In stage C, packed cell volume was greater than both preclinical stages (C: 43.84 ±0.46). When the administration of loop diuretics was included in statistical models, packed cell volume was inversely related to normalised left ventricular internal diameters (β: -2.37; 95% confidence intervals: -3.49, -1.25; P < 0.001).

CLINICAL SIGNIFICANCE

Dogs with myxomatous mitral valve disease may develop reductions in packed cell volume as their disease progresses. Although this finding was statistically significant at a population level, it should be noted that the differences described are relatively small. This, along with other causes of variation in packed cell volume, means that changes would be challenging to appreciate within individual patients. Plasma volume depletion following diuretic administration may explain why findings differed in stage C.

Investigation of the transforming growth factor-beta 1 signalling pathway as a possible link between hyperphosphataemia and renal fibrosis in feline chronic kidney disease

•

Chronic kidney disease (CKD) is associated with development of hyperphosphataemia.

•

Severity of renal fibrosis has been correlated with degree of hyperphosphataemia.

•

Transforming growth factor-β1 (TGF-β1) is a major pro-fibrotic mediator in CKD.

•

A phosphate restricted diet did not affect urinary active TGF-β1 excretion in cats.

•

Increased extracellular phosphate had no pro-fibrotic effect on feline renal cells.

Chronic kidney disease (CKD) is common in geriatric cats, and is characterised in the majority of cases by tubulointerstitial inflammation and fibrosis. Hyperphosphataemia is a frequent complication of CKD and is independently associated with severity of renal fibrosis and disease progression. Transforming growth factor-beta 1 (TGF-β1) signalling is thought to be a convergent pathway which mediates the progression of renal fibrosis in CKD. The aims of this study were to explore the interaction between increased extracellular phosphate and the TGF-β1 signalling pathway by investigating: (a) the effect of a commercially available, phosphate-restricted, diet on urinary TGF-β1 excretion in cats with CKD; and (b) the role of increased extracellular phosphate in regulating proliferation, apoptosis, and expression of genes related to TGF-β1 signalling and extracellular matrix (ECM) production in feline proximal tubular epithelial cells (FPTEC) and cortical fibroblasts from cats with azotaemic CKD (CKD-FCF).

The dietary intervention study revealed no effect of dietary phosphate restriction on urinary active TGF-β1 excretion after 4–8 weeks (P = 0.98), despite significantly decreasing serum phosphate (P < 0.001). There was no effect of increased growth media phosphate concentration (from 0.95 mM to 2 mM and 3.5 mM) on proliferation (P = 0.99) and apoptotic activity in FPTEC (P = 0.22), or expression of genes related to ECM production and the TGF-β1 signalling pathway in FPTEC and CKD-FCF (P > 0.05). These findings suggest the beneficial effects of dietary phosphate restriction on progression of feline CKD may not occur through modulation of renal TGF-β1 production, and do not support a direct pro-fibrotic effect of increased extracellular phosphate on feline renal cells.

The new age of renal biomarkers: does SDMA solve all of our problems?

Within clinical small animal practice, diagnosis of both chronic kidney disease and acute kidney injury is common. To assess renal function, measurement of glomerular filtration rate is considered the gold standard. Currently, routine tests of kidney function include surrogate markers of glomerular filtration rate such as serum creatinine, and urea, each with their own limitations, whilst urine protein to creatinine ratio gives an indication of glomerular and tubular handling of protein, and urine specific gravity information about urine concentrating ability by the kidney. These parameters are used together with historical and physical examination data to give a diagnosis of kidney disease following which creatinine, proteinuria and blood pressure are used to stage chronic kidney disease and, together with urine output, grade acute kidney injury according to the International Renal Interest Society. However, there has been much concern that creatinine is insensitive when used to indicate early decline in renal function and this has highlighted the need for additional methods of diagnosing and monitoring these patients, with the potential to allow earlier therapeutic intervention. Symmetric dimethylarginine is a novel biomarker, which has been shown to perform as a surrogate marker of glomerular filtration rate in small animals. This article will review current research on symmetric dimethylarginine and the ways in which it may be utilised in small animal practice; current research supports the use of symmetric dimethylarginine as a screening test for detection of early chronic kidney disease according to International Renal Interest Society guidelines, but further research is required in to the usefulness of symmetric dimethylarginine as a tool for monitoring disease and the effect of non-renal influences.