Use of natural experimental studies to evaluate 20mph speed limits in two major UK cities.

INTRODUCTION: Reductions in traffic speed can potentially offer multiple health and public health benefits. In 2016, implementation of 20mph (30kph) speed limit interventions began in Edinburgh (city-wide) and Belfast (city centre). The aims of this paper are to describe 1) the broad theoretical approach and design of two natural experimental studies to evaluate the 20mph speed limits in Edinburgh and Belfast and 2) how these studies allowed us to test and explore theoretical mechanisms of 20mph speed limit interventions. METHODS: The evaluation consisted of several work packages, each with different research foci, including the political decision-making processes that led to the schemes, their implementation processes, outcomes (including traffic speed, perceptions of safety, and casualties) and cost effectiveness. We used a combination of routinely and locally collected quantitative data and primary quantitative and qualitative data. RESULTS: The evaluation identified many contextual factors influencing the likelihood of 20mph speed limits reaching the political agenda. There were substantial differences between the two sites in several aspects related to implementation. Reductions in speed resulted in significant reductions in collisions and casualties, particularly in Edinburgh, which had higher average speed at baseline. The monetary value of collisions and casualties prevented are likely to exceed the costs of the intervention and thus the overall balance of costs and benefits is likely to be favourable. CONCLUSIONS: Innovative study designs, including natural experiments, are important for assessing the impact of 'real world' public health interventions. Using multiple methods, this project enabled a deeper understanding of not only the effects of the intervention but the factors that explain how and why the intervention and the effects did or did not occur. Importantly it has shown that 20mph speed limits can lead to reductions in speed, collisions and casualties, and are therefore an effective public health intervention.

A simple tool for comparing benefits and 'costs' of COVID-19 exit strategies.

BACKGROUND: Governments and health policymakers are now looking for strategies to lift the COVID-19 lockdown, while reducing risk to the public. METHODS: We propose the population attributable risk (PAR) as an established epidemiological tool that could support decision-making through quickly estimating the main benefits and costs of various exit strategies. RESULTS: We demonstrate the feasibility of use of PAR using pandemic data, that were publicly available in mid-May 2020 from Scotland and the US, to estimate the proportion of COVID-19 hospital admissions which might be avoided, and the proportion of adverse labour market effects - for various scenarios - based on maintaining the lockdown for those of certain ages with and without comorbidities. CONCLUSION: These calculations could be refined and applied in different countries to inform important COVID-19 policy decisions, using routinely collected data.

Sensitivity and specificity of time resolved point dose measurements for patient specific quality assurance.

This study aimed to quantify the sensitivity and specificity of time-resolved point dose measurements. Criteria were defined to assess whether errors would cause a clinically relevant dose deviation during patient treatment. The sensitivity and specificity were determined based on verification measurements of five error-free plans and 84 intentional error plans. Receiver operator characteristic analysis was conducted to quantify the efficiency of the method. In addition, the specificity of the method was investigated in more detail by assessing its ability to identify different error modes. For measurements made at planning target volume locations, a moderate sensitivity (65% ± 13%), specificity (76% ± 12%), and an area under the curve (AUC) equal to 0.77 were obtained for a quality control (QC) acceptance criterion of 2%. Measurements made at organ at risk (OAR) locations had high sensitivity (80% ± 20%), but low specificity (54% ± 13%), and an AUC equal to 0.70. The low specificity for OAR locations could be traced to the impact of a small couch tilt on measurement locations at larger distances from the isocentre, resulting in increased shielding by multi-leaf collimator (MLC) leaves. Further analysis showed that output errors and errors affecting the penumbra region can be resolved on a per measurement basis with moderate to high sensitivity (100% and 67% for errors in output, and in the penumbra region, respectively) and high specificity (77% and 85% for errors in output, and in the penumbra region, respectively). This can potentially result in saving time investigating failing QC measurements.

Nicolau Syndrome (Embolia Cutis Medicamentosa): A Rare and Poorly Recognized Iatrogenic Cause of Cutaneous Thrombotic Vasculopathy.

Nicolau syndrome is a rare form of iatrogenic cutaneous necrosis which affects injection sites. Although classically associated with intramuscular injections, it may develop after subcutaneous or other routes of parenteral drug administration. Clinically, it manifests as necrotic ulcers that often develop in a background of erythematous and livedoid reticular patches. The histopathologic characteristics of Nicolau syndrome are poorly documented in the dermatopathology literature and features only rarely as one of the obscure causes of cutaneous thrombotic vasculopathy. We report a case of Nicolau syndrome developing secondary to subcutaneous injection of cyclizine to familiarize the clinicians and pathologists to this unusual condition. Given that it is potentially avoidable, pathologists should alert the clinicians to the possibility of Nicolau syndrome when a skin biopsy from an injection site shows signs of extensive thrombotic vasculopathy.

UK Renal Registry 18th Annual Report: Chapter 8 Haemoglobin, Ferritin and Erythropoietin amongst UK Adult Dialysis Patients in 2014: National and Centre-specific Analyses.

In the UK in 2014: The median haemoglobin (Hb) of patients at the time of starting dialysis was 100 g/L with 50% of patients having a Hb 5100 g/L. The median Hb in patients starting haemodialysis (HD) was 97 g/L (IQR 87-106) and in patients starting peritoneal dialysis (PD) was 108 g/L (IQR 100-117). At start of dialysis, 54% of patients presenting early had Hb 5100 g/L whilst only 33% of patients presenting late had Hb 5100 g/L. The median Hb of prevalent patients on HD was 111 g/L with an IQR of 103-120 g/L. The median Hb of prevalent patients on PD was 112 g/L with an IQR of 103-121 g/L. 81% of HD patients and 83% of PD patients had Hb 5100 g/L. 58% of HD patients and 56% of PD patients had Hb 5100 and 4120 g/L. The median ferritin in HD patients was 432 mg/L (IQR 274­631) and 95% of HD patients had a ferritin 5100 mg/L. The median ferritin in PD patients was 292 mg/L (IQR 168­479) with 88% of PD patients having a ferritin 5100 mg/L. In England, Wales and Northern Ireland in 2014: The median erythropoietin stimulating agent (ESA) dose was higher for HD than PD patients (7,333 vs. 4,148 IU/week).

Revised Baux Score and updated Charlson comorbidity index are independently associated with mortality in burns intensive care patients.

PURPOSE: The purpose of the current study was to utilise established scoring systems to analyse the association of (i) burn injury severity, (ii) comorbid status and (iii) associated systemic physiological disturbance with inpatient mortality in patients with severe burn injuries admitted to intensive care. METHODS: Case notes of all patients with acute thermal injuries affecting ≥15% total body surface area (TBSA) admitted to the Burns Intensive Care Unit (BICU) at Chelsea and Westminster Hospital during a 10-year period were retrospectively reviewed. Revised Baux Score, Belgian Outcome in Burn Injury (BOBI) Score, Abbreviated Burn Severity Index (ABSI), APACHE II Score, Sequential Organ Failure Assessment (SOFA) Score and Updated Charlson Comorbidity Index (CCI) were computed for each patient and analysed for association with inpatient mortality. RESULTS: Ninety mechanically ventilated patients (median age 45.7 years, median % TBSA burned 36.5%) were included. 72 patients had full thickness burns and 35 patients had inhalational injuries. Forty-four patients died in hospital while 46 survived to discharge. In a multivariate logistic regression model, only the Revised Baux Score (p<0.001) and updated CCI (p=0.014) were independently associated with mortality. This gave a ROC curve with area under the curve of 0.920. On multivariate cox regression survival analysis, only the Revised Baux Score (p<0.001) and the updated CCI (p=0.004) were independently associated with shorter time to death. CONCLUSION: Our data suggest that the Revised Baux Score and the updated CCI are independently associated with inpatient mortality in patients admitted to intensive care with burn injuries affecting ≥15% TBSA. This emphasises the importance of comorbidities in the prognosis of patients with severe burn injuries.

UK Renal Registry 17th Annual Report: Chapter 7 Haemoglobin, Ferritin and Erythropoietin amongst UK Adult Dialysis Patients in 2013: National and Centre-specific Analyses.

BACKGROUND: The diagnosis and management of anaemia in chronic kidney disease and the standards to be achieved have been detailed in the UK Renal Association Anaemia of CKD guidelines. AIMS: To determine the attainment of standards for anaemia management in the UK. METHODS: Quarterly data were obtained for haemoglobin (Hb) and factors that influence Hb from renal centres in England,Wales, Northern Ireland (EW&NI) and the Scottish Renal Registry for the incident and prevalent renal replacement therapy (RRT) cohorts for 2013. RESULTS: In the UK, in 2013,50% of patients commenced dialysis therapy with Hb 5100 g/L (median Hb 100 g/L). Of patients presenting early, 53% started dialysis with Hb 5100 g/L compared to 36% of patients presenting late. The UK median Hb of haemodialysis (HD) & peritoneal dialysis (PD) patients was 112 g/L (inter-quartile range (IQR) 103­120 g/L) and 113 g/L(IQR 103­122 g/L) respectively with 83% of patients having Hb .100 g/L for both treatment modalities. The median ferritin in HD and PD patients was 424 mg/L (IQR 280­616 mg/L) and 285 mg/L (IQR 167­473 mg/L) respectively with the majority of patients achieving ferritin 5100 mg/L.In EW&NI the median ESA dose was higher for HD than PD patients (7,333 vs. 4,000 IU/week). The percentage of patients treated with an ESA and having Hb .120 g/L ranged between centres from 3­29% for HD and from 0­26% for PD. CONCLUSIONS: There continues to be significant variation between centres in the use of iron and ESAi n order to achieve the target Hb (100­120 g/L).

Electrocardiographic features and prevalence of bilateral bundle-branch delay.

BACKGROUND: Definitive diagnosis of bilateral bundle-branch delay/block may be made when catheter-induced right bundle-branch block (RBBB) develops in patients with baseline left bundle-branch (LBB) block. We hypothesized that a RBBB pattern with absent S waves in leads I and aVL will identify bilateral bundle-branch delay/block. METHODS AND RESULTS: Fifty patients developing transient RBBB pattern in lead V1 during right heart catheterization were studied. Patients were grouped according to whether the baseline ECG demonstrated a normal QRS, left fascicular blocks, or LBB block pattern. The RBBB morphologies in each group were compared. The prevalence of bilateral bundle-branch delay/block pattern was examined in our hospital ECG database. All patients with baseline normal QRS complexes (n=30) or left fascicular blocks (4 anterior, 5 posterior) developed a typical RBBB pattern. Among the 11 patients with a baseline LBB block pattern, 7 developed an atypical RBBB pattern with absent S waves in leads I and aVL and the remaining 4 demonstrated a typical RBBB. The absence of S waves in leads I and aVL during RBBB was 100% specific and 64% sensitive for the presence of pre-existing LBB block. Among the consecutive 2253 hospitalized patients with RBBB, 34 (1.5%) had the bilateral bundle-branch delay/block pattern. CONCLUSIONS: An ECG pattern of RBBB in lead V1 with absent S wave in leads I and aVL indicates concomitant LBB delay. Pure RBBB and bifascicular blocks are associated with S waves in leads I and aVL.

Independent effects of systemic and peritoneal inflammation on peritoneal dialysis survival.

Systemic inflammation, as evidenced by elevated inflammatory cytokines, is a feature of advanced renal failure and predicts worse survival. Dialysate IL-6 concentrations associate with variability in peritoneal small solute transport rate (PSTR), which has also been linked to patient survival. Here, we determined the link between systemic and intraperitoneal inflammation with regards to peritoneal membrane function and patient survival as part of the Global Fluid Study, a multinational, multicenter, prospective, combined incident and prevalent cohort study (n=959 patients) with up to 8 years of follow-up. Data collected included patient demographic characteristics, comorbidity, modality, dialysis prescription, and peritoneal membrane function. Dialysate and plasma cytokines were measured by electrochemiluminescence. A total of 426 survival endpoints occurred in 559 incident and 358 prevalent patients from 10 centers in Korea, Canada, and the United Kingdom. On patient entry to the study, systemic and intraperitoneal cytokine networks were dissociated, with evidence of local cytokine production within the peritoneum. After adjustment for multiple covariates, systemic inflammation was associated with age and comorbidity and independently predicted patient survival in both incident and prevalent cohorts. In contrast, intraperitoneal inflammation was the most important determinant of PSTR but did not affect survival. In prevalent patients, the relationship between local inflammation and membrane function persisted but did not account for an increased mortality associated with faster PSTR. These data suggest that systemic and local intraperitoneal inflammation reflect distinct processes and consequences in patients treated with peritoneal dialysis, so their prevention may require different therapeutic approaches; the significance of intraperitoneal inflammation requires further elucidation.

ErbB3 downregulation enhances luminal breast tumor response to antiestrogens.

Aberrant regulation of the erythroblastosis oncogene B (ErbB) family of receptor tyrosine kinases (RTKs) and their ligands is common in human cancers. ErbB3 is required in luminal mammary epithelial cells (MECs) for growth and survival. Since breast cancer phenotypes may reflect biological traits of the MECs from which they originate, we tested the hypothesis that ErbB3 drives luminal breast cancer growth. We found higher ERBB3 expression and more frequent ERBB3 gene copy gains in luminal A/B breast cancers compared with other breast cancer subtypes. In cell culture, ErbB3 increased growth of luminal breast cancer cells. Targeted depletion of ErbB3 with an anti-ErbB3 antibody decreased 3D colony growth, increased apoptosis, and decreased tumor growth in vivo. Treatment of clinical breast tumors with the antiendocrine drug fulvestrant resulted in increased ErbB3 expression and PI3K/mTOR signaling. Depletion of ErbB3 in fulvestrant-treated tumor cells reduced PI3K/mTOR signaling, thus decreasing tumor cell survival and tumor growth. Fulvestrant treatment increased phosphorylation of all ErbB family RTKs; however, phospho-RTK upregulation was not seen in tumors treated with both fulvestrant and anti-ErbB3. These data indicate that upregulation of ErbB3 in luminal breast cancer cells promotes growth, survival, and resistance to fulvestrant, thus suggesting ErbB3 as a target for breast cancer treatment.

Chapter 7 Adequacy of haemodialysis in UK adult patients in 2010: national and centre-specific analyses.

BACKGROUND: Outcome in patients treated with haemodialysis (HD) is influenced by the delivered dose of dialysis. The UK Renal Association (RA) publishes clinical practice guidelines which include recommendations for dialysis dose. The urea reduction ratio (URR) is a widely used measure of dialysis dose. AIM: To determine the extent to which patients received the recommended dose of HD in the UK. METHODS: All seventy-two UK renal centres submitted data to the UK Renal Registry (UKRR). Two groups of patients were included in the analyses: the prevalent patient population on 31st December 2010 and the incident patient population for 2010. Centres returning data on <50% of their patient population or centres with <20 patients were excluded from centre-specific comparisons. RESULTS: Data regarding URR were available from 64 renal centres in the UK. Forty nine centres provided URR data on more than 90% of prevalent patients. The proportion of patients in the UK who met the UK clinical practice guideline for URR (>65%) increased from 56% in 1998 to 86% in 2010. There was persistent variation observed between centres, with 19 centres attaining the RA clinical practice guideline in >90% of patients and 39 centres attaining the guideline in 70-90%. The overall proportion of prevalent patients with a URR >65% has continued to improve over time. CONCLUSIONS: The delivered dose of HD for patients with established renal failure has increased over the last decade. Whilst the majority of UK patients achieved the target URR there was considerable variation between centres in the percentage of patients achieving the guideline.

UK Renal Registry 12th Annual Report (December 2009): chapter 8: adequacy of haemodialysis in UK renal centres in 2008: national and centre-specific analyses.

BACKGROUND: Outcome in patients treated with haemodialysis (HD) is influenced by the delivered dose of dialysis. The UK Renal Association (RA) publishes Clinical Practice Guidelines which include recommendations for dialysis dose. The urea reduction ratio (URR) is a widely used measure of dialysis dose. AIM: To determine the extent to which patients received the recommended dose of HD in the UK. METHODS: Seventy-two renal centres in the UK submit data electronically to the UK Renal Registry (UKRR). Two groups of patients were included in the analyses: the prevalent patient population on 31st December 2008 and the incident patient population for 2008. Centres returning data on <50% of their patient population were excluded from centre-specific comparisons. RESULTS: Data regarding URR were available from 62 renal centres in the UK. Fifty-one centres provided URR data on more than 90% of prevalent patients. There has been an increase from 56% in 1998 to 83% in 2008 in the proportion of patients in the UK who met the UK Clinical Practice Guideline for URR (>65%). There was considerable variation from one centre to another, with 9 centres attaining the RA clinical practice guideline in >90% of patients and 5 centres attaining the standard in <70% of patients. The HD dose (URR) delivered to patients who had just started dialysis treatment was lower than that of patients who had been treated for longer and increased further with time. CONCLUSIONS: The delivered dose of HD for patients with established renal failure has increased over 10 years. Whilst the large majority of patients in the UK achieved the target URR there was considerable variation between centres in the percentage of patients achieving this.

UK Renal Registry 12th Annual Report (December 2009): chapter 11: blood pressure profile of prevalent patients receiving dialysis in the UK in 2008: national and centre-specific analyses.

INTRODUCTION: The UK Renal Registry (UKRR) assesses blood pressure (BP) control annually for patients receiving renal replacement therapy (RRT) at renal centres in England, Wales and Northern Ireland. METHODS: Patients alive and receiving RRT on 31st December 2008 with a BP reading in either the fourth or third quarter of 2008 were included. Summary statistics were calculated for each renal centre, nation and primary renal disease (PRD) category. Longitudinal analyses were performed to assess the long-term impact of treatment modality and PRD on BP control for incident and prevalent patients. RESULTS: In 2008, only 26.3% of peritoneal dialysis (PD) and 27.4% of transplant (Tx) patients achieved the Renal Association (RA) guidelines standard of BP <130/80 mmHg. Since the cessation of BP targets for haemodialysis (HD) patients, there has been a reduction (compared to 2007) in the number of HD patients achieving BP <130/80 mmHg. In 2008, 43.1% of patients achieved BP <140/90 mmHg pre-HD and 46.8% BP <130/ 80 mmHg post-HD. BP control varied significantly between renal centres for each treatment modality (p < 0.001). Adjusted mean systolic BP fell significantly during the first year on dialysis (6 mmHg for PD and 8 mmHg for HD). Hypertension was more common in HD patients with vascular disorders such as diabetes and renovascular disease (59.0%) than in patients with glomerulonephritis (51.9%) or tubular disorders (46.7%). CONCLUSIONS: In 2008, a minority of patients on RRT achieved the recommended BP standards. There remained a significant variation in achievement of standards between UK renal centres. Since the removal of specific BP targets for HD patients, there has been an increase in systolic BP pre-and post-HD. BP falls significantly during the first year after starting dialysis and patients with vascular disorders have significantly worse BP control.

UK Renal Registry 11th Annual Report (December 2008): Chapter 8 Adequacy of haemodialysis in UK renal centres in 2007: national and centre-specific analyses.

BACKGROUND: Outcome in patients treated with haemodialysis (HD) is influenced by the delivered dose of dialysis. The UK Renal Association (RA) publishes Clinical Practice Guidelines which include recommendations for dialysis dose. The urea reduction ratio (URR) is a widely used measure of dialysis dose. AIM: To determine the extent to which patients received the recommended dose of HD in the UK. METHODS: Seventy-one renal centres in the UK submit data electronically to the UK Renal Registry (UKRR). Two groups of patients were included in the analyses: the prevalent patient population on 31st December 2007 and the incident patient population for 2007. Centres returning data on <50% of their patient population were excluded from centre-specific comparisons. RESULTS: Data regarding URR were available from 61 renal centres in the UK. Forty six centres provided URR data on more than 90% of prevalent patients. 81% of prevalent HD patients met the UK Clinical Practice Guideline for URR (>65%) in 2007. There has been an increase from 56% in 1998 to 81% in 2007 in the proportion of patients in the UK who achieved a URR >65%. The HD dose (URR) delivered to patients who have just started dialysis treatment is lower than that of patients who have been treated for longer and increases further with time. CONCLUSIONS: The delivered dose of HD for patients with established renal failure has increased over 9 years. There was considerable variation from one centre to another, with 8 centres attaining the RA clinical practice guideline in >90% of patients and 7 centres attaining the standard in <60% of patients.

UK Renal Registry 11th Annual Report (December 2008): Chapter 9 Haemoglobin, ferritin and erythropoietin amongst patients receiving dialysis in the UK in 2007: national and centre-specific analyses.

BACKGROUND: The UK Renal Association (RA) and National Institute for Health and Clinical Excellence (NICE) have published Clinical Practice Guidelines which include recommendations for management of anaemia in established renal failure. AIMS: To determine the extent to which the guidelines for anaemia management are met in the UK. METHODS: Quarterly data (haemoglobin (Hb) and factors that influence Hb) extracts from renal centres in England, Wales and Northern Ireland (EWNI), and annual data from the Scottish Renal Registry for incident and prevalent renal replacement therapy (RRT) cohorts for 2007 were analysed by the UK Renal Registry (UKRR). RESULTS: In the UK, in 2007 58% of patients commenced dialysis therapy with Hb > or = 10.0 g/dl (median Hb 10.3 g/dl). Of incident patients 81% and 87% had a Hb > or = 10.0 g/dl by 3 and 6 months of dialysis treatment respectively. The median Hb of haemodialysis (HD) patients was 11.6 g/dl with an interquartile range (IQR) of 10.6-12.6 g/dl. Of HD patients 86% had a Hb > or = 10.0 g/dl. The median Hb of peritoneal dialysis (PD) patients in the UK was 11.9 g/dl (IQR 11.0-12.8 g/dl). 91% of UK PD patients had a Hb > or = 10.0 g/dl. The median ferritin in HD patients in EWNI was 417 microg/L (IQR 270-598) and 95% of HD patients had a ferritin > or = 100 microg/L. The median ferritin in PD patients was 255 microg/L (IQR 143-411) with 85% of PD patients having a ferritin > or = 100 microg/L. In EWNI the mean ESA dose was higher for HD than PD patients (9,300 vs. 6,100 IU/week). CONCLUSIONS: This year for the first time there has been a small fall (from 85.9% in 2006 to 85.6%) in the percentage of HD patients with an Hb of > or = 10 g/dl. This contrasts with previous annual improvements in this figure and is related to implementation of the new Hb Standard which has a target range of 10.5-12.5 g/dl.

UK Renal Registry 11th Annual Report (December 2008): Chapter 11 Blood pressure profile of prevalent patients receiving dialysis in the UK in 2007: national and centre-specific analyses.

INTRODUCTION: Blood pressure (BP) control is assessed annually from patients on Renal Replacement Therapy at renal centres in England, Wales and Northern Ireland by the UK Renal Registry. METHODS: Patients alive and receiving RRT on 31st December 2007 with a BP reading in either the fourth or third quarter of 2007 were included. Summary statistics were calculated for each renal centre, nation and renal disease category. Linear regression analyses were performed for prevalent patients between 2000 and 2007. RESULTS: Significantly more haemodialysis patients achieved the BP standard (44.6% pre-HD and 48.8% post-HD) than peritoneal dialysis (32.8%) or renal transplant patients (26.7%). Median BP fell significantly between 2000 and 2007 for each treatment modality. There was significant variability in BP control between renal centres (p < 0.0001) for haemodialysis and transplant patients. Hypertension was significantly more common in haemodialysis patients with vascular disorders such as diabetes and renovascular disease (56.8%) than in glomerulonephritis (51.0%) or tubular disorders (45.1%). The effect was less prominent in peritoneal dialysis and not evident in transplant patients where few achieved the BP standard. CONCLUSION: A minority of patients on RRT achieved BP standards in 2007. There remained a significant variation in achievement of standards between renal centres.

Reponses of sheep to a vaccination of entodinial or mixed rumen protozoal antigens to reduce rumen protozoal numbers.

Two rumen protozoa vaccine formulations containing either whole fixed Entodinium or mixed rumen protozoa cells were tested on Merino sheep with the aim of decreasing the number and/or activity of protozoa in the rumen. Negative control (no antigen) and positive control (Tetrahymena corlissi antigens) treatments were also included in the experiment. Blood and saliva were sampled to measure the specific immune response. Protozoal numbers in the rumen were monitored by microscopic counts. Vaccination with protozoal formulations resulted in the presence of specific IgG in plasma and saliva, but saliva titres were low. Titres after secondary vaccination were higher (P 0.05) by the vaccination and there was also no difference (P>0.05) between treatments in rumen fluid ammonia-N concentration or wool growth. In vitro studies investigated the binding ability of the antibodies and estimated the amount of antibody required to reduce cell numbers in the rumen. The studies showed that the antibodies did bind to and reduced protozoa numbers, but the amount of antibody generated by vaccination was not enough to produce results in an in vivo system. It is suggested that the vaccine could be improved if specific protozoal antigens are determined and isolated and that improved understanding of the actions of protozoa antibodies in rumen fluid and the relationships between levels of antibodies and numbers of protozoa in the rumen is needed.