Parity violation constraints using cosmic microwave background polarization spectra from 2006 and 2007 observations by the QUaD polarimeter

We constrain parity-violating interactions to the surface of last scattering using spectra from the QUaD experiment's second and third seasons of observations by searching for a possible systematic rotation of the polarization directions of cosmic microwave background photons. We measure the rotation angle due to such a possible "cosmological birefringence" to be 0.55 degrees +/-0.82 degrees (random) +/-0.5 degrees (systematic) using QUaD's 100 and 150 GHz temperature-curl and gradient-curl spectra over the spectra over the multipole range 200<l<2000, consistent with null, and constrain Lorentz-violating interactions to <2 x 10;{-43} GeV (68% confidence limit). This is the best constraint to date on electrodynamic parity violation on cosmological scales.

Application of flowcell technology for monitoring biofilm development and cellulose degradation in leachate and rumen systems

In this study, a flat plate flowcell was modified to provide a reactor system that could maintain anaerobic, cellulolytic biofilms while providing the data needed to carry out a chemical oxygen demand mass balance to determine the cellulose digestion rates. The results showed that biofilms could be observed to grow and develop on cellulose particle surfaces from both anaerobic digester leachate and rumen fluid inocula. The observations suggest that the architecture of rumen and leachate derived biofilms may be significantly different with rumen derived organisms forming stable, dense biofilms while the leachate derived organisms formed less tenacious surface attachments. This experiment has indicated the utility of flowcells in the study of anaerobic biofilms.

The effect of biomass density on cellulose solubilisation rates

The aim of this work was to compare the impact of inoculation density on the rate of cellulose hydrolysis by a rumen derived culture with that of a microbial enrichment from an organic waste anaerobic digester. The results showed a linear relationship between the mass of biomass at the start of the first order degradation phase (Xo) and the first order hydrolysis rate (r) for both rumen inoculated and leachate inoculated cellulose digestions and that the slopes of these relationships were not distinguishable. This suggested that differences in the microbial community, media and other environmental factors had a lesser impact on the hydrolysis rate compared to the effect of the number of cells in the system. This could be of great importance to industrial applications of anaerobic digestion technologies as it suggested that if cells densities in the waste treatment digesters could be boosted to match those seen in the rumen, then the rates of the cellulose hydrolysis would rise.

A survey of the relative abundance of specific groups of cellulose degrading bacteria in anaerobic environments using fluorescencein situhybridization

AIMS

The utility of fluorescence in situ hybridization (FISH) for detecting uncultured micro-organisms in environmental samples has been shown in numerous habitats. In this study a suite of three FISH probes for cellulolytic bacteria is described and their efficacy is demonstrated by quantifying the relative abundance of the target micro-organisms in a range of industrial biomass samples.

METHODS AND RESULTS

The probes were designed from data derived from an artificial landfill leachate reactor study and 16S rRNA gene databases. The original biomass sample proved to be well described by the three probes targeting a total of 51% of the bacterial (EUBMIX targeted) cells in quantitative FISH experiments.

CONCLUSIONS

Three probes were developed and applied to samples from a range of industrial digesters. The CSTG1244 probe, specific for organisms closely related to Clostridium stercorarium, were observed in the widest range of samples (7 of the 19 samples tested). The CTH216a FISH probe, specific for organisms closely related to Clostridium thermocellum, described the highest proportion of the bacterial population within any one sample (46% in an anaerobically digested sludge sample). Finally, the BCE216a probe, specific for organisms closely related to Bacteroides cellulosolvens, achieved the lowest level of hybridisation of the three probes tested.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrates that the three groups of anaerobic cellulolytic micro-organisms were present in different bioreactors but at variable abundances ranging from low (where other organisms would have been responsible for cellulolysis) to high. We showed the potential of using group specific FISH probes and quantitative FISH in environmental studies. The utility of using newly designed FISH probes was demonstrated by their ability to detect and quantify the target bacterial groups in samples from a range of industrial wastewater digesters.

Abdominopelvic mesh compartmentalization reduces the complications of radiotherapy in children: a preliminary report

AIM

The aim of this report was to assess the effects of radiotherapy (RT) in children with abdominopelvic tumours in whom a biodegradable (Polyglactin 910) mesh had been inserted prior to commencement of radiotherapy.

METHODS

Retrospective analysis was carried out of four patients with abdominopelvic tumours who underwent radiotherapy between 2000 and 2002 as part of their management.

RESULTS

All children tolerated radiotherapy well with no evidence of acute or chronic radiation enteritis. One child developed prolonged postoperative ileus and a second child developed infective diarrhoea and fever, not related to radiation.

CONCLUSION

We have highlighted a good tolerance of radiotherapy in children following the insertion of a Polyglactin 910 mesh prior to starting radiation and would recommend further larger studies with longer follow-up to support this.

EFFECTS OF BOTULINUM TOXIN B ON REFRACTORY DETRUSOR OVERACTIVITY: A RANDOMIZED, DOUBLE-BLIND, PLACEBO CONTROLLED, CROSSOVER TRIAL

PURPOSE

Open, observational studies of intradetrusor injections of botulinum toxin for detrusor overactivity have reported beneficial effects. We tested the efficacy and safety of botulinum toxin B for the treatment of the overactive bladder in a randomized, double-blind, placebo controlled crossover trial.

MATERIALS AND METHODS

A total of 20 patients 18 to 80 years old with detrusor overactivity unresponsive to oral antimuscarinic agents participated in the study. They were injected with either placebo (20 ml normal saline) or botulinum toxin B (5,000 IU diluted up to 20 ml) intravesically in a day case setting. After 6 weeks the treatments were crossed over without washout in line with previous findings. The primary outcome was the paired difference in change in average voided volumes. Frequency, incontinence episodes and paired differences in quality of life measured by the King's Health Questionnaire were the secondary outcome measures.

RESULTS

The Wilcoxon signed ranks test was used to test the paired difference in change between treatment phases. Little carryover was noted in the second arm placebo and the placebo data from both arms were included in analysis. There were clinically statistically significant paired differences in the change in average voided volume, urinary frequency and episodes of incontinence between active treatment and placebo (average voided volume: 95% CI difference 16, 122; Z2.5; p = 0.012/weekly frequency: 95% CI -21, -1; Z2.1, p=0.033/weekly incontinence: 95% CI -26, -7; Z3.3; p = 0.001). There were similarly significant paired differences in the change in quality of life affecting 5 domains of the King's Health Questionnaire.

CONCLUSIONS

This double-blind, placebo controlled, crossover study provides evidence of the efficacy of botulinum toxin B in the treatment of overactive bladder. Autonomic side effects were observed in 4 patients. The short duration of action will presumably limit the use to patients who have experienced tachyphylaxis with botulinum toxin A.

Hepatitis C among drug users: consensus guidelines on management in general practice

BACKGROUND

Hepatitis C (HCV) is a common cause of morbidity among patients who attend general practitioners (GPs) in Ireland for methadone maintenance treatment.

AIMS

To describe the development and content of guidelines for the management of HCV among current or former opiate users in the Eastern Regional Health Authority area attending GPs for methadone treatment.

METHODS

The guidelines were produced in five stages: identification of key stakeholders; development of evidence-based draft guidelines; discussion of content; determination of 'Delphi'-facilitated consensus and review by a sample of GPs for whom the guidelines would be intended.

RESULTS

The guidelines contain advice for GPs on all aspects of care of patients at risk of HCV, including general and preventative care, care of other bloodborne and hepatotoxic viruses, and the factors to be considered and appropriate evaluation prior to referring a patient for assessment at a hepatology unit.

CONCLUSIONS

GPs have an important role to play in the care of patients at risk of, or infected with, HCV.

Identification, detection, and spatial resolution of Clostridium populations responsible for cellulose degradation in a methanogenic landfill leachate bioreactor

An anaerobic landfill leachate bioreactor was operated with crystalline cellulose and sterile landfill leachate until a steady state was reached. Cellulose hydrolysis, acidogenesis, and methanogenesis were measured. Microorganisms attached to the cellulose surfaces were hypothesized to be the cellulose hydrolyzers. 16S rRNA gene clone libraries were prepared from this attached fraction and also from the mixed fraction (biomass associated with cellulose particles and in the planktonic phase). Both clone libraries were dominated by Firmicutes phylum sequences (100% of the attached library and 90% of the mixed library), and the majority fell into one of five lineages of the clostridia. Clone group 1 (most closely related to Clostridium stercorarium), clone group 2 (most closely related to Clostridium thermocellum), and clone group 5 (most closely related to Bacteroides cellulosolvens) comprised sequences in Clostridium group III. Clone group 3 sequences were in Clostridium group XIVa (most closely related to Clostridium sp. strain XB90). Clone group 4 sequences were affiliated with a deeply branching clostridial lineage peripherally associated with Clostridium group VI. This monophyletic group comprises a new Clostridium cluster, designated cluster VIa. Specific fluorescence in situ hybridization (FISH) probes for the five groups were designed and synthesized, and it was demonstrated in FISH experiments that bacteria targeted by the probes for clone groups 1, 2, 4, and 5 were very abundant on the surfaces of the cellulose particles and likely the key cellulolytic microorganisms in the landfill bioreactor. The FISH probe for clone group 3 targeted cells in the planktonic phase, and these organisms were hypothesized to be glucose fermenters.

Intrapartum ultrasound estimation of total bladder volume

OBJECTIVE

To determine whether real-time ultrasound measurement of multiple linear dimensions of the bladder could be used to estimate total bladder volumes of women in labour.

AIM

To create a simple reproducible formula using ultrasound techniques to help estimate total bladder volumes of women in labour. This may prevent unnecessary catheterisation and conversely, avoid failure to catheterise when indicated, thereby reducing the complications associated with catheterisation and bladder overdistension.

DESIGN

Prospective, observational study of women in labour.

SETTING

Delivery Suite, Obstetric Hospital, University College London Hospitals.

POPULATION

Forty-nine women in labour recommended for catheterisation by their attending midwives.

METHOD

A real-time ultrasound scanner was used to measure bladder diameters in two planes: transverse width and height, and sagittal width and height. A Foley's catheter was inserted and the bladder drained into a graduated bowl under sterile conditions. These values and urine volumes were recorded and a formula for detecting bladder volumes above 300 mL was developed using linear regression methods and the Bland-Altman limits of agreement.

MAIN OUTCOME MEASURE

Sensitivity and specificity of derived formulae in predicting bladder volume from ultrasound measurements. Correctly predicted volumes greater than 300 mL.

RESULTS

Among the 49 women, 36 were nulliparous and 13 were multiparous. All had full-term pregnancies with cephalic presentation and were in active labour with cervical dilatations ranging from 3 to 10 cm. There were no previous caesarean sections among the multiparous women. Thirty-nine women had epidural analgesia. Indications for catheterisation included a palpable bladder per abdomen, or the interval from last urine voided. The catheterised volumes ranged from 30 to 720 mL with a median of 150 mL. The new equation (0.68 x h x d x w) had a sensitivity of 77% (95% CI 46-95%) and specificity of 86% (95% CI 71-95%) for detecting bladder volumes greater than 300 mL. In order to ensure that about 95% of women in need of catheterisation are detected, the above equation was improved using the Bland-Altman limits of agreement. The sensitivity of this final equation (1.74 x h x d x w) was 100% (95% CI 75-100%) and the specificity dropped to 36% (95% CI 21-54%).

CONCLUSION

It is possible to use real-time ultrasound in estimation of total bladder volumes of women in labour. The implications are that all of those normally selected as being in need of catheterisation could be detected, while about a quarter of those women would avoid unnecessary catheterisation.

MUC1 expression, splice variant and short form transcription (MUC1/Z, MUC1/Y) in prostate cell lines and tissue

OBJECTIVE

To detect the expression and transcription pattern of MUC1 in benign and malignant disease, and in two widely studied cell lines, and to investigate the glycosylation of MUC-1 in bone metastasis of prostate cancer, as mucins have been implicated in the progression and behaviour of several cancers.

MATERIALS AND METHODS

RNA extracted from cell lines (DU145 and PC3), five samples of BPH and five samples of prostate cancer was reverse transcribed before amplification of MUC1-specific sequences by polymerase chain reaction. Paraffin-embedded sections were stained for glycosylated MUC1 and MUC1 core epitopes by HMFG1 and B27.29 antibodies, respectively. Steroid-treated cell lines were analysed by fluorescence-activated cell sorting, using the same antibodies.

RESULTS

MUC1, in an under-glycosylated form, was widely expressed in the prostate and in metastatic lesions. MUC1/Z and MUC1/Y RNA were differentially expressed in BPH and prostate cancer, with no detectable expression of splice variant mRNA. This is in contrast to prostate cancer cell line cells (PC3 and DU145), which express splice variant mRNA.

CONCLUSIONS

BPH, prostate cancer and metastatic prostate cancer all express high levels of under-glycosylated MUC1. This may explain the inability of previous studies to detect MUC1 in prostate tissue, as the antibody used was specific for a carbohydrate epitope which is not expressed on the under-glycosylated MUC1.

Assessment of surgeon competency to remove mandibular third molar teeth

There is an increasing demand for methods to objectively assess a surgeon's competence. The purpose of this study is to test two evaluation methods that assess a surgeon's skills in the removal of mandibular third molar teeth. One method uses an objective checklist scale by which twenty components of the operation are judged as correct or incorrect. The second method is a global rating scale, that scores different aspects of performance, such as respect for tissue, number of manoeuvres, knowledge of procedure and instrument handling. Using these two methods, assessors judged the removal of 22 mandibular third molar teeth by 17 different surgeons. Good inter-rater reliability was achieved using both scales. A greater preference was expressed for the global rating scale for assessment and for the objective checklist scale for guiding feedback in training. Scales such as these need to be developed for, and tested on, different surgical procedures in order that credible assessment of surgical skills can be obtained.

Some factors affecting cerebral tissue saturation during obstructive sleep apnoea

Measurement of cerebral tissue saturation during obstructive sleep apnoea (OSA) may provide additional information to conventional peripheral oxygen saturation. Thirteen subjects with OSA (mean apnoea/hypopnoea index 65.7+/-27.9) were monitored using full polysomnography and monitoring of near-infrared cerebral tissue oxygenation index (TOI). One-thousand and thirty-six apnoeas and hypopnoeas were analysed, in terms of duration, sleep stage, arterial oxygen saturation (Sa,O2) dip, minimum Sa,O2, TOI dip and minimum TOI. Cerebral TOI is a measure of cerebral tissue saturation of haemoglobin with oxygen, calculated using near-infrared spatially resolved spectroscopy, which has been shown to have a high specificity for intracranial changes. Decreases in cerebral oxygenation were observed during apnoeas and hypopnoeas. Baseline TOI ranged from 50.1-73.0% and mean apnoea/hypopnoea related TOI dips ranged from 1.43-6.85%. Mean Sa,O2 dips varied from 3.8-21.7%. In regression analysis, factors significantly predicting the magnitude of the TOI dip were Sa,O2 dip, minimum Sa,O2, apnoea duration and rapid eye movement sleep stage. The effect of apnoea duration and sleep stage remained significant after Sa,O2 was included in the regression equation. Near-infrared spectroscopy provides a noninvasive technique for monitoring cerebral tissue saturation during obstructive sleep apnoea.

The champagne angle

A patient's observation led us to investigate whether drinking from a champagne flute required more cranio-cervical extension than drinking from other types of wine glasses. We measured the cranio-cervical extension required by normal volunteers to drink from four different types of glass. The mean [95% confidence intervals] extension from the neutral position required to drain each glass was: narrow flute 40 degrees [35-44]; wide flute 22 degrees [19-25]; wine glass 26 degrees [24-29]; champagne saucer 0 degree [-1-2]. Drinking from the narrow rimmed champagne flute required significantly more extension than the other types of glass (p < 0.001), and 73% of the total available cranio-cervical extension.

Expression of oestrogen receptor beta (ERbeta1) protein in human breast cancer biopsies

Oestrogen action is mediated via specific receptors that act as ligand-activated transcription factors. A monoclonal antibody specific to the C-terminus of human oestrogen receptor beta has been characterized and the prevalence of expression of oestrogen receptor beta protein investigated in a well defined set of breast cancers. Reverse transcription-polymerase chain reaction analysis of RNA from tissue biopsies detected oestrogen receptor beta in all samples examined. The anti-oestrogen receptor beta antibody cross reacted specifically with both long (approximately 59 Kd) and short (approximately 53 Kd) forms of recombinant oestrogen receptor beta. Western blot analysis of breast tumours contained both forms of oestrogen receptor beta protein although in some samples lower molecular weight species (32--45 Kd) were identified. Fifty-one breast cancer biopsies were examined using immunohistochemistry; 41 (80%) were immunopositive for oestrogen receptor alpha, 48 (94%) were immunopositive for oestrogen receptor beta and 38 (74.5%) co-expressed both receptors. Expression of oestrogen receptor beta was exclusively nuclear and occurred in multiple cell types. There was no quantitative relationship between staining for the two ERs although in tumours in which both receptors were present immunoexpression of oestrogen receptor alpha was invariably more intense. The significance of oestrogen receptor beta protein expression in breast cancers to therapy remains to be determined but the availability of a well characterized antibody capable of detecting oestrogen receptor beta in archive material will facilitate the process.

Are we really as good as we think we are?

Differences are examined in assessment and self-assessment scores, in oral and maxillofacial surgery trainees and MSc postgraduates, following the surgical removal of lower third molar teeth. This study found evidence of a surprising and worrying over-rating of their own surgical skills by many trainees and postgraduates.

Right and left ventricular long-axis function in the fetus using angular M-mode

OBJECTIVE

Long-axis function is determined by the longitudinally oriented myocardial fibers. Postnatally, conventional M-mode is used to assess tricuspid and mitral valve ring movements in relation to the cardiac apex. During fetal life, this is precluded by variable fetal position. We assessed the feasibility of determining right and left ventricular long-axis function in the fetus.

METHODS

A prospective, pilot study. The four-chamber view obtained during routine fetal echocardiography was recorded in a cineloop to which B-mode guided M-mode echocardiography was applied using angular M-mode. This allowed retrospective and correct placement of the cursor line from cardiac apex to tricuspid or mitral valve rings. M-mode tracings of the valve ring movements in relation to the apex were derived from the originally stored loop. Data from 18 fetuses (17-29 weeks of gestation) were available for analysis. Total excursion of the valve rings was measured offline. A second cursor line was simultaneously placed in the left ventricular outflow tract during color flow mapping for timing purposes (n = 6).

RESULTS

Right and left ventricular long-axis recordings were obtained in 18 and 14 cases, respectively. Total right ventricular excursion was 5.2 mm (SD, 0.9 mm) (range, 3.9-7.2 mm). Total left ventricular free wall excursion was 4.5 mm (SD, 1.1 mm) (range, 3.0-6.8 mm). For paired data, the mean of differences (right ventricle-left ventricle) was 0.8 mm (95% confidence interval 0.5-1.2). The valve rings moved towards the apex during systole (shortening) and away from it during diastole (lengthening). Peak downward movement coincided with cessation of aortic flow and diastolic lengthening with flow through the atrioventricular valves.

CONCLUSION

Long-axis function in the fetus is feasible if M-mode angle correction is used. There was no clinically significant difference between tricuspid and mitral valve excursions. The pattern of atrioventricular valve movement is coordinate and similar to that of adults. Long-axis function offers a new avenue to study systolic and diastolic function in the fetus.

Assessment of cardiac risk before peripheral vascular surgery: a comparison of myocardial perfusion imaging and long axis echocardiography at rest

OBJECTIVE

To compare resting long axis echocardiography with adenosine thallium-201 emission tomography in detecting myocardial ischaemic abnormalities and surgical related risk in patients before peripheral vascular surgery.

DESIGN

A prospective and blinded pre-operative examination of resting left ventricular minor and long axes and myocardial perfusion during adenosine vasodilation using thallium-201 emission tomography.

SETTING

A tertiary referral centre for cardiac and vascular disease equipped with invasive, non-invasive and surgical facilities.

SUBJECTS

65 patients (40 male) with significant peripheral vascular disease, mean age 63+/-10 (S.D.) years, and 21 normal subjects of similar age.

RESULTS

Thallium-201 myocardial perfusion tomography was abnormal in 50/65 patients; 27 had fixed, 23 reversible abnormalities (19 of whom had both). Long axis was considered abnormal if one or more of two systolic long axis disturbances, reduced extent of total excursion <1 cm at any of the three (left, septal and posterior left ventricular) sites or prolonged shortening >1 mm after A2, and two diastolic abnormalities, delayed onset of lengthening >80 ms after A2 or reduced peak lengthening velocity <4.5 cm/s, was present. Long axis score (maximum 12) was based on the presence or absence of these four disturbances at each of the three sites. Myocardial perfusion imaging with thallium-201 classified the patients into three different groups according to their liability to low, moderate or high surgical risk (summed stress perfusion score of 36). Thirteen of 50 patients were identified as subjects at high surgical risk, with a perfusion score of 22/36 and below. Twelve of these demonstrated significantly greater impairment of systolic and diastolic long axis function, compared to those at low surgical risk, with a total long axis echo score of 6/12 or more. Seventeen of 18 patients identified as being at low surgical risk, with a perfusion score of 32/36 and above, had total long axis score of less than 6/12. The remaining 19 moderate risk patients had a wide range of long axis scores. In the 65 patients studied there were two post-operative deaths, one post-discharge death due to cerebrovascular accident, and one due to renal failure.

CONCLUSION

The combination of both systolic and diastolic long axis disturbances in patients with peripheral vascular disease can be used to predict the thallium assessment of surgical risk. Long axis echocardiography may thus have value as a screening test before non-cardiac surgery as well as providing a means of monitoring myocardial perfusion.

Incremental importance of peak-exercise plasma levels of endothelin-1 and natriuretic peptides in chronic heart failure

Chronic heart failure (CHF) studies investigating the clinical, hemodynamic, and therapeutic importance of endothelin-1 (ET-1), atrial natriuretic peptide (ANP), and brain natriuretic peptide (BNP) are largely based on resting plasma levels, which may vary with prior exertion and postprandial status. This study investigated the importance of peak-exercise plasma levels of ET-1, ANP, and BNP in the assessment of left ventricular (LV) systolic function. Thirty-six male-patients ages 58 +/- 10 (mean +/- SD ) with NYHA class I-IV CHF due to coronary artery disease or idiopathic dilated cardiomyopathy were enrolled. LV systolic function was assessed by echocardiography and radionuclide ventriculography. Resting and peak cardiopulmonary exercise venous blood sampling and treadmill exercise testing were performed in the fasting state. Resting plasma levels of ET-1, ANP, and BNP were elevated compared with reference laboratory normal values. Exercise induced significant (p < 0.0001) increase in plasma levels of ET-1, ANP, and BNP. On univariate analysis peak-exercise plasma levels of ET-1, ANP, and BNP were more closely related to echocardiographically determined LV end-diastolic diameter and end-systolic diameter than their resting values. Multiple step-wise regression models identified resting and peak-exercise plasma levels of ET-1 and ANP but only the resting BNP as independent predictors of LV dimensions and systolic function. Peak exercise plasma levels of ANP and ET-1 are potentially more reliable and important than their resting levels as markers of LV systolic dysfunction and LV dimensions in patients with heart failure.

Cross sectional study of primary care groups in London: association of measures of socioeconomic and health status with hospital admission rates

OBJECTIVES

To calculate socioeconomic and health status measures for the primary care groups in London and to examine the association between these measures and hospital admission rates.

DESIGN

Cross sectional study.

SETTING

66 primary care groups in London, total list size 8.0 million people.

MAIN OUTCOME MEASURES

Elective and emergency standardised hospital admission ratios; standardised admission rates for diabetes and asthma.

RESULTS

Standardised hospital admission ratios varied from 74 to 116 for total admissions and from 50 to 124 for emergency admissions. Directly standardised admission rates for asthma varied from 152 to 801 per 100 000 (mean 364) and for diabetes from 235 to 1034 per 100 000 (mean 538). There were large differences in the mortality, socioeconomic, and general practice characteristics of the primary care groups. Hospital admission rates were significantly correlated with many of the measures of chronic illness and deprivation. The strongest correlations were with disability living allowance (R=0.64 for total admissions and R=0.62 for emergency admissions, P<0.0001). Practice characteristics were less strongly associated with hospital admission rates.

CONCLUSIONS

It is feasible to produce a range of socioeconomic, health status, and practice measures for primary care groups for use in needs assessment and in planning and monitoring health services. These measures show that primary care groups have highly variable patient and practice characteristics and that hospital admission rates are associated with chronic illness and deprivation. These variations will need to be taken into account when assessing performance.

Correlation between bovine milk somatic cell count and polymorphonuclear leukocyte level for samples of bulk milk and milk from individual cows

The influence of various factors on the concentrations of polymorphonuclear neutrophilic leukocytes (PMN) in milk samples from bulk tanks and individual cows was investigated. While somatic cell counts (SCC) and PMN level were in both cases significantly correlated, lower correlation coefficients were found between SCC and PMN for samples of bulk tank milks than for milk samples from individual cows. Furthermore, plots of PMN concentrations versus SCC showed great variability in PMN in milk samples of similar total SCC. One factor that may lead to variability in bulk tank PMN levels was shown to be increased proportions of high SCC milk in the bulk tank mixture, which result in relatively high PMN levels without excessive elevation of total SCC. In milk samples from individual cows, it was found that there was also a significant seasonal influence on milk PMN content, with milk from cows calving in the spring having, at SCC > 160,000 cells/ ml, higher proportions of PMN in the total milk SCC than milk from autumn calving cows. The results of this study suggest that the concentration of PMN may be a useful indicator of herd status in bulk tank monitoring schemes.