Histopathology-Based Deep-Learning Predicts Atherosclerotic Lesions in Intravascular Imaging

Background: Optical coherence tomography is a powerful modality to assess atherosclerotic lesions, but detecting lesions in high-resolution OCT is challenging and requires expert knowledge. Deep-learning algorithms can be used to automatically identify atherosclerotic lesions, facilitating identification of patients at risk. We trained a deep-learning algorithm (DeepAD) with co-registered, annotated histopathology to predict atherosclerotic lesions in optical coherence tomography (OCT). Methods: Two datasets were used for training DeepAD: (i) a histopathology data set from 7 autopsy cases with 62 OCT frames and co-registered histopathology for high quality manual annotation and (ii) a clinical data set from 51 patients with 222 OCT frames in which manual annotations were based on clinical expertise only. A U-net based deep convolutional neural network (CNN) ensemble was employed as an atherosclerotic lesion prediction algorithm. Results were analyzed using intersection over union (IOU) for segmentation. Results: DeepAD showed good performance regarding the prediction of atherosclerotic lesions, with a median IOU of 0.68 ± 0.18 for segmentation of atherosclerotic lesions. Detection of calcified lesions yielded an IOU = 0.34. When training the algorithm without histopathology-based annotations, a performance drop of >0.25 IOU was observed. The practical application of DeepAD was evaluated retrospectively in a clinical cohort (n = 11 cases), showing high sensitivity as well as specificity and similar performance when compared to manual expert analysis. Conclusion: Automated detection of atherosclerotic lesions in OCT is improved using a histopathology-based deep-learning algorithm, allowing accurate detection in the clinical setting. An automated decision-support tool based on DeepAD could help in risk prediction and guide interventional treatment decisions.

Sfaira accelerates data and model reuse in single cell genomics

Single-cell RNA-seq datasets are often first analyzed independently without harnessing model fits from previous studies, and are then contextualized with public data sets, requiring time-consuming data wrangling. We address these issues with sfaira, a single-cell data zoo for public data sets paired with a model zoo for executable pre-trained models. The data zoo is designed to facilitate contribution of data sets using ontologies for metadata. We propose an adaption of cross-entropy loss for cell type classification tailored to datasets annotated at different levels of coarseness. We demonstrate the utility of sfaira by training models across anatomic data partitions on 8 million cells.

The International Atomic Energy Agency action plan on radiation protection of patients and staff in interventional procedures: Achieving change in practice

INTRODUCTION

The International Atomic Energy Agency (IAEA) organized the 3rd international conference on radiation protection (RP) of patients in December 2017. This paper presents the conclusions on the interventional procedures (IP) session.

MATERIAL AND METHODS

The IAEA conference was conducted as a series of plenary sessions followed by various thematic sessions. "Radiation protection of patients and staff in interventional procedures" session keynote speakers presented information on: 1) Risk management of skin injuries, 2) Occupational radiation risks and 3) RP for paediatric patients. Then, a summary of the session-related papers was presented by a rapporteur, followed by an open question-and-answer discussion.

RESULTS

Sixty-seven percent (67%) of papers came from Europe. Forty-four percent (44%) were patient studies, 44% were occupational and 12% were combined studies. Occupational studies were mostly on eye lens dosimetry. The rest were on scattered radiation measurements and dose tracking. The majority of patient studies related to patient exposure with only one study on paediatric patients. Automatic patient dose reporting is considered as a first step for dose optimization. Despite efforts, paediatric IP radiation dose data are still scarce. The keynote speakers outlined recent achievements but also challenges in the field. Forecasting technology, task-specific targeted education from educators familiar with the clinical situation, more accurate estimation of lens doses and improved identification of high-risk professional groups are some of the areas they focused on.

CONCLUSIONS

Manufacturers play an important role in making patients safer. Low dose technologies are still expensive and manufacturers should make these affordable in less resourced countries. Automatic patient dose reporting and real-time skin dose map are important for dose optimization. Clinical audit and better QA processes together with more studies on the impact of lens opacities in clinical practice and on paediatric patients are needed.

IAEA experience in communicating radiation risks through the RPOP website

The authors report here their successful experience of communicating information to health professionals, patients and the public on benefits and risks of ionising radiation in medical applications. The approaches used have been based on giving importance to clinical benefits against risks, as well as safety in use against risk of use. Communicating brief messages against catchy questions with positive and pragmatic approach resulted in making website on radiation protection of patients (RPOP) as the top website of the world in this area. Credibility of information has been maintained. The results show immense outreach in 213 countries/territories.

Justification of diagnostic medical exposures: some practical issues. Report of an International Atomic Energy Agency Consultation

OBJECTIVES

The Radiation Protection of Patients Unit of the International Atomic Energy Agency (IAEA) is concerned about the effectiveness of justification of diagnostic medical exposures. Recent published work and the report of an initial IAEA consultation in the area gave grounds for such concerns. There is a significant level of inappropriate usage, and, in some cases, a poor level of awareness of dose and risk among some key groups involved. This article aims to address this.

METHODS

The IAEA convened a second group of experts in November 2008 to review practical and achievable actions that might lead to more effective justification.

RESULTS

This report summarises the matters that this group considered and the outcome of their deliberations. There is a need for improved communication, both within professions and between professionals on one hand, and between professionals and the patients/public on the other. Coupled with this, the issue of consent to imaging procedures was revisited. The need for good evidence-based referral guidelines or criteria of acceptability was emphasised, as was the need for their global adaptation and dissemination.

CONCLUSION

Clinical audit was regarded as a key tool in ensuring that justification becomes an effective, transparent and accountable part of normal radiological practice. In summary, justification would be facilitated by the "3 As": awareness, appropriateness and audit.

ICRP publication 112. A report of preventing accidental exposures from new external beam radiation therapy technologies

Disseminating the knowledge and lessons learned from accidental exposures is crucial in preventing re-occurrence. This is particularly important in radiation therapy; the only application of radiation in which very high radiation doses are deliberately given to patients to achieve cure or palliation of disease. Lessons from accidental exposures are, therefore, an invaluable resource for revealing vulnerable aspects of the practice of radiotherapy, and for providing guidance for the prevention of future occurrences. These lessons have successfully been applied to avoid catastrophic events with conventional technologies and techniques. Recommendations, for example, include the independent verification of beam calibration and independent calculation of the treatment times and monitor units for external beam radiotherapy, and the monitoring of patients and their clothes immediately after brachytherapy. New technologies are meant to bring substantial improvement to radiation therapy. However, this is often achieved with a considerable increase in complexity, which in turn brings opportunities for new types of human error and problems with equipment. Dissemination of information on these errors or mistakes as soon as it becomes available is crucial in radiation therapy with new technologies. In addition, information on circumstances that almost resulted in serious consequences (near-misses) is also important, as the same type of events may occur elsewhere. Sharing information about near-misses is thus a complementary important aspect of prevention. Lessons from retrospective information are provided in Sections 2 and 4 of this report. Disseminating lessons learned for serious incidents is necessary but not sufficient when dealing with new technologies. It is of utmost importance to be proactive and continually strive to answer questions such as 'What else can go wrong', 'How likely is it?' and 'What kind of cost-effective choices do I have for prevention?'. These questions are addressed in Sections 3 and 5 of this report. Section 6 contains the conclusions and recommendations. This report is expected to be a valuable resource for radiation oncologists, hospital administrators, medical physicists, technologists, dosimetrists, maintenance engineers, radiation safety specialists, and regulators. While the report applies specifically to new external beam therapies, the general principles for prevention are applicable to the broad range of radiotherapy practices where mistakes could result in serious consequences for the patient and practitioner.

A Method of Predicting Workload and Staffing Level for Radiotherapy Treatment Planning as Plan Complexity Changes

When assessing the impact on workload from an expanding number of new patients and increasing treatment complexity, radiotherapy clinics find that oversimplified workload parameters, such as number of patients or number of fields, are not suitable for managing and predicting workload and organisational dimension. Although the basic treatment equivalent concept is available for predicting linear accelerator utilisation, no corresponding parameter has been available for radiotherapy treatment planning. In this study, we derive a simple workload indicator for treatment planning. The dose plan unit (DPU) takes the complexity of the treatment plan into account. Categorising plans according to complexity in their production, and measuring corresponding time for completing the plans in these categories, leads to the following baseline values for workload prediction: 1 DPU (non-computed tomography [CT]), 3 DPU (CT-contour) and 6 DPU (full-CT). The measured average productivity of 0.65 DPU per hour (1 standard deviation, SD = 0.08 DPU), or alternatively 1 DPU = 92 min, for a dosimetrist in this clinic indicates that 79.0 DPU can be produced by each dosimetrist per month within normal working hours. The predictive power of the DPU is shown in terms of using it to quantify the impact on workload in treatment planning of changing treatment protocols for a particular anatomic treatment site.

Dose escalation of chart in non-small cell lung cancer: is three-dimensional conformal radiation therapy really necessary?

PURPOSE

To evaluate, preclinically, the potential for dose escalation of continuous, hyperfractionated, accelerated radiation therapy (CHART) for non small-cell lung cancer (NSCLC), we examined the strategy of omission of elective nodal irradiation with and without the application of three-dimensional conformal radiation technology (3DCRT).

METHODS AND MATERIALS

2D, conventional therapy plans were designed according to the specifications of CHART for 18 patients with NSCLC (Stages Ib, IIb, IIIa, and IIIb). Further plans were generated with the omission of elective nodal irradiation (ENI) from the treatment portals (2D minus ENI plans [2D-ENI plans]). Both sets were inserted in the patient's planning computed tomographies (CTs). These reconstructed plans were then compared to alternative, three-dimensional treatment plans which had been generated de novo, with the omission of ENI: 3D minus elective nodal irradiation (3D-ENI plans). Dose delivery to the planning target volumes (PTVs) and to the organs at risk were compared between the 3 sets of corresponding plans. The potential for dose escalation of each patient's 2D-ENI and 3D-ENI plan beyond 54 Gy, standard to CHART, was also determined.

RESULTS

PTV coverage was suboptimal in the 2D CHART and the 2D-ENI plans. Only in the 3D-ENI plans did 100% of the PTV get > or = 95% of the dose prescribed (i.e., 51.5 Gy [51.3-52.2]). Using 3D-ENI plans significantly reduced the dose received by the spinal cord, the mean and median doses to the esophagus and the heart. It did not significantly reduce the lung dose when compared to 2D-ENI plans. Escalation of the dose (minimum > or = 1 Gy) with optimal PTV coverage was possible in 55.5% of patients using 3D-ENI, but was possible only in 16.6% when using the 2D-ENI planning strategy.

CONCLUSIONS

3DCRT is fundamental to achieving optimal PTV coverage in NSCLC. A policy of omission of elective nodal irradiation alone (and using 2D technology) will not achieve optimal PTV coverage or dose escalation. 3DCRT with omission of ENI can achieve true escalation of CHART in 55.5% of tumors, depending on their site and N-stage.

What margins should be added to the clinical target volume in radiotherapy treatment planning for lung cancer?

BACKGROUND

The planning target volume in radiotherapy treatment planning takes into account both movements of the clinical target volume (CTV) and set-up deviations.

MATERIALS AND METHODS

A group of patients who received radiotherapy for lung cancer were studied. In order to measure the CTV movements due to respiration and other internal organ motions, fluoroscopy was performed for 20 patients. To study the accuracy and reproducibility of patient and beam set-up, 553 electronic portal images from 20 patients were evaluated. Discrepancies between planned and actual field positions were measured and the systematic and random errors were identified. The combined effect of these geometrical variations was evaluated.

RESULTS

The average CTV movement with quiet respiration was about 2.4 mm in the medio-lateral and dorso-ventral directions. Movement in the cranio-caudal direction was on average 3.9 mm with a range of 0-12 mm. The systematic set-up errors were on average 2.0 mm in the transversal plane and 3.0 mm in the cranio-caudal direction. The random errors can be described by their standard deviations of 3.2 and 2.6 mm. In this study, the combined effect of the two parameters (CTV movement and set-up deviations) varied between 7.5 and 10.3 mm in different anatomical directions.

CONCLUSIONS

In our daily clinical routine, we use a margin of 11 mm in the transversal plane and 15 mm cranially and caudally, also taking into account other unquantified variations and uncertainties.

Improvements in absorbed dose measurements for external radiation therapy using ferrous dosimeter gel and MR imaging (FeMRI)

A ferrous gel, based on ferrous (Fe) sulphate and agarose, was used with a clinical magnetic resonance imaging (MRI) scanner to obtain relative dose distribution data from therapeutic photon and electron beams. The FeMRI gel was scanned using a new MRI acquisition protocol optimized for T1 measurements. Thorough comparisons with silicon semiconductor detector and ionization chamber measurements, as well as with Monte Carlo calculations, were performed in order to quantify the improvements obtained using FeMRI for dose estimations. Most of the relative doses measured with FeMRI were within 2% of the doses measured with other methods. The larger discrepancies (2-4%) found at shallow depths are discussed. The uncertainty in relative dose measurements using FeMRI was significantly improved compared with previously reported results (5-10%, one standard deviation, 1 SD), and is today between 1.6% and 3.3% (depending on dose level, 2 SD). This corresponds to an improvement in the minimum detectable dose (3 SD above background) from approximately 2 Gy to better than 0.6 Gy. The results obtained in this study emphasize the importance of obtaining basic FeMRI dose data before the method is extended to complicated treatment regimes.

Effect of set-up uncertainties on the dose distribution in the match region of supraclavicular and tangential breast fields

BACKGROUND

The objective of this paper is to illustrate the effect of a gap of 5 mm, an overlap of 5 mm and a perfect match on the dose distribution across the junction of tangential breast fields and adjacent supraclavicular and axillary fields.

MATERIALS AND METHODS

For this purpose film dosimetry was applied to measure relative dose distributions in two sagittal planes in an anthropomorphic breast phantom having cork lungs, simulating a radiation therapy treatment of the breast and adjacent supraclavicular lymph nodes. Two different treatment techniques, an SSD match technique and a geometrically exact isocentric match technique, as routinely applied in the two institutes were examined. The three-dimensional treatment planning system of each institute was used to calculate the dose distribution in the match region of the supraclavicular fields and the two opposing tangential fields. The measured and calculated dose distributions were evaluated and compared along lines in two sagittal planes from the supraclavicular fields down to the tangential fields crossing the match planes. These dose distributions in the match region were extremely dependent on the set-up of the fields.

RESULTS

Although the reproducibility of the film measurements was within 2%, it became clear that the set-up of the fields to achieve a gap of 5 mm, a perfect match or an overlap of 5 mm required a lot of attention, even when using a phantom.

CONCLUSIONS

It can be concluded that in clinical practice, these set-up difficulties do influence the dose distribution in the match region much more than the systematic uncertainties in the dose calculation algorithms of the treatment planning systems and the type of treatment technique.

Respiratory burst activity of phagocytic cells isolated from the mammary glands and blood of camels (Camelus bactrianus)

The oxidative burst activity of phagocytic cells isolated from camel blood and mammary glands was studied using a chemiluminescence (Cl) assay. The polymorphonuclear leucocytes (PMNL) isolated from camel blood mounted a luminol-dependent Cl response upon stimulation with opsonized zymosan or opsonized Staphylococcus aureus. These responses showed an overall similarity to those described in other mammalian species. The leucocytes isolated from the mammary glands mounted Cl responses similar to those observed with blood PMNL but to a lower magnitude. Like the Cl responses of blood cells, the Cl responses induced by mammary gland leucocytes were associated with degranulation and the release of lysosomal enzymes such as myeloperoxidase (MPO).

In vivo determination of the accuracy of field matching in breast cancer irradiation using an electronic portal imaging device

The purpose of this study was to investigate the accuracy of field matching in patients treated by irradiation of the breast and adjacent lymph nodes. Field matching is performed by the radiographers during each session on a match line drawn on the patient's skin. Field edge positions were assessed in the cranial match plane of tangential breast fields and supraclavicular-axillary fields using an electronic portal imaging device and match line markers placed on the skin of the patients. The mean gap/overlap of the four fields for individual patients during each treatment session, derived from 374 marker projections, was +0.5 mm indicating that no systematic gap or overlap was observed. The uncertainty in the position of the four fields with respect to the match plane ranges from 3.1 to 5.1 mm (1 SD) for the individual patients. Gaps and overlaps between fields were also related to an absolute match line position, found by comparison of simulator and portal images, showing a small systematic uncertainty of 2.4 mm and a standard deviation of 3.3 mm. It can be concluded that the use of an electronic portal imaging device in combination with match line markers is a good method to quantify the accuracy of field matching in vivo. The results showed good stability and reproducibility in the field matching region for this treatment technique of breast cancer irradiation.

Isolation and purification of bovine myeloperoxidase from neutrophil granules

Bovine myeloperoxidase (MPO) was isolated and purified from neutrophil granules using protein extraction at pH 4 and gel filtration combined with fast protein liquid chromatography. The extracted protein was identified as MPO based on its absorption spectrum, amino acid composition, peroxidase activity and polypeptide structure. Bovine neutrophils contained three different forms of MPO (I, II and III). When subjected to sodium dodecyl sulphate polyacrylamide gel electrophoresis each of the three purified forms showed two distinct bands corresponding to heavy and light polypeptide chains of approximately 57,000 and 15,000 molecular radius. Amino acid analysis of the three forms showed that there was an overall similarity between them. Slight differences were found between MPO Form III and the other two forms. The three forms of bovine MPO were shown to differ in their specific enzyme activities in a luminol-dependent chemiluminescence assay. MPO Form III showed the highest enzyme activity. The amount recovered during purification of the respective MPO forms varied, with the recovery being highest for MPO I. Our findings suggest that there are intrinsic differences between the three forms of bovine MPO. In terms of their amino acid composition and molecular weight, the bovine MPO closely resembled human and canine MPO.

Species identification and some characteristics of coagulase-negative staphylococci isolated from bovine udders

The species of 203 strains of coagulase-negative staphylococci (CNS), isolated from bovine udder quarters was determined; all were tested for hydrophobicity and encapsulation, attributes that may relate to virulence. Twelve species were identified, of which Staphylococcus simulans, (34.5%), S. chromogenes (16.7%), S. epidermidis (13.8%) and S. xylosus (8.9%) were the most frequent. The majority of strains possessed a hydrophilic cell surface. However, strains from two species (S. chromogenes and S. epidermidis) were more hydrophobic than the others. Only five strains were encapsulated (S. xylosus, 3; S. saprophyticus, 1; and S. sciuri, 1). Judging from the low frequencies of hydrophobic and encapsulated strains, and comparing with strains isolated from clinical cases, it is suggested that these properties are not major virulence determinants of CNS.

Bacteriological investigations of clinical mastitis in heifers in Sweden

Bacterial analyses were carried out of 2069 udder secretions, isolated from 1481 heifers with mastitis in eight veterinary districts in Sweden. Streptococci, e.g. Streptococcus dysgalactiae and Str. uberis, dominated the bacterial flora, being isolated from 34.4 and 19.5% respectively of heifers with clinical mastitis occurring from puberty up to 14 d post partum. Bacterial species generally regarded as important pathogens in the summer mastitis complex, e.g. Actinomyces pyogenes, Stuart-Schwan coccus and strictly anaerobic bacteria such as Peptostreptococcus indolicus, Fusobacterium necrophorum and Bacteroides melaninogenicus were isolated at low frequencies (13.2, 6.3, 9.4, 3.8 and 1.3% respectively). When the cases of mastitis studied were restricted to those appearing in heifers pre partum, May 15 to October 14 (summer mastitis), these bacterial species were isolated at higher percentages (27.1, 14.4, 21.4, 13.5 and 5.2% respectively). These figures were, nevertheless, still lower than those published in reports from other countries. Whether considered up to 14 d post partum or only pre partum, there were no significant differences in the frequencies of A. pyogenes isolated at different seasons. There were geographical differences in bacterial incidence, e.g. Staphylococcus aureus was isolated significantly more often in northern regions whereas Str. dysgalactiae was more common in the south. This and other Swedish investigations support the theory that A. pyogenes and strictly anaerobic bacteria are 'secondary invaders' that depend on Str. dysgalactiae to cause a primary infection. It is stressed that the udders of all heifers should be examined daily so that cases of mastitis can be treated immediately.

Adhesive proteins of haemagglutinating Staphylococcus aureus isolated from bovine mastitis

Two proteins derived from the cell wall of Staphylococcus aureus, exhibiting apparent molecular masses of 116 kDa and 145 kDa, were found to bind to human buccal and bovine lactiferous sinus epithelial cells. By using antibodies specific for fibronectin-binding protein of S. aureus of human origin, the 116 kDa protein, but not the 145 kDa protein, was identified as a fibronectin-binding protein. The 145 kDa protein bound to bovine fat globule membranes, human buccal epithelial cells, bovine lactiferous sinus epithelial cells and sheep erythrocytes. The properties of the 145 kDa protein suggest that it is an adhesin with a possible role in the early stages of the development of bovine mastitis.

Ability of bovine mammary macrophages to enhance proliferation of autologous blood and mammary secretion lymphocytes

Cells were obtained by centrifuging the mammary secretion of healthy udders of 19 cows during the dry-period and during mid-lactation. The suspended cells were incubated in plastic wells. Those adhered cells classified as mammary macrophages were incubated with pokeweed mitogen (PWM). Autologous peripheral blood lymphocytes were added to wells containing untreated macrophage cultures or cultures pretreated with PWM. In seven cows autologous dry-period mammary lymphocytes were added instead of blood lymphocytes. The macrophages + lymphocyte cultures were subjected to the lymphocyte stimulation test (LST). For comparison, peripheral blood lymphocytes and dry-period secretion lymphocytes were also subjected to the LST in the presence of PWM. In all cases, mitogenic responses were higher in pretreated macrophage cultures than in background control cultures. The stimulation indices (SI) showed that PWM-pretreated dry-period mammary macrophages enhanced the proliferation of autologous peripheral blood lymphocytes to a greater extent than did blood lymphocytes plus PWM (49 +/- 10 v. 30 +/- 6; P less than or equal to 0.05). Mammary macrophages taken from the same cows but during midlactation also clearly induced proliferation of autologous peripheral blood lymphocytes but to a lesser extent than dry-period macrophages (16 +/- 2 v. 49 +/- 10; 16 +/- 2 v. 30 +/- 6; P less than or equal to 0.01 and P less than or equal to 0.05). The PWM pretreatment of mammary macrophages increased the proliferation of autologous dry-period mammary lymphocytes by at least a factor of three (28 +/- 8 v. 8 +/- 2 P less than or equal to 0.05). The present results indicate that bovine mammary macrophages pretreated with PWM enhance proliferation as well as modulation of mammary and peripheral blood lymphocytes. The modulation of lymphocyte stimulation as demonstrated here in vitro, has great significance regarding aspects of local immunostimulation related to modern treatment of mastitis.

A preliminary study of uterine derived polymorphonuclear cell function in mares with chronic uterine infections

From 6 mares with chronic uterine infection, polymorphonuclear neutrophils (PMNs) were obtained from the uterus. In order to recover an adequate number of viable PMNs, 0.1% oyster glycogen was infused into the uterus as a mild irritant 12 h prior to the uterine flushing. Phagocytosis and chemotaxis of the uterine derived PMNs were determined. The supernatant from the uterine flushing was compared with autologous serum for its capacity as an opsonin and chemoattractant. There was a significant increase of both phagocytosis and chemotaxis when autologous serum was used compared with the supernatant from the uterine flushing. This study indicates that autologous serum has a greater opsonizing capacity than uterine secretion from mares with chronic uterine infection. Since all mares conceived following this study, the use of oyster glycogen was not considered to have deleterious effect on the uterine mucosa.

Plasminogen activation in the bovine udder

Plasmin is a serin protease with a broad substrate specificity which might cause disintegration of basal membranes, epithelium and surrounding matrix. Plasmin might also elicit degradation of tissue (Mullins & Rohrlich 1983).

Effects of parity and stage of lactation on adenosine triphosphate, somatic cell count and antitrypsin content in cows' milk

Significant effects of parity and stage of lactation were found on ATP content, somatic cell count and antitrypsin content when using morning milk samples from 39 cows over a period of 18 months. A close similarity was evident between variation in ATP and somatic cell count, except during the first 10 d after parturition when the variation in ATP was more pronounced. The same result was obtained in the whole material as well as in a healthy subset. This study shows clearly that parity and stage of lactation must be taken into account when establishing normal values for ATP as an indicator of mastitis.

Studies of defence mechanisms and inflammatory reactions in the bovine teat using a new experimental method

Bovine intramammary infections are usually caused by microorganisms entering through the teat canal. The teat canal normally acts as a mechanical and physiological barrier preventing bacteria from entering the teat cistern. This barrier can be broken, e.g. if the teat end is damaged, making it possible for bacteria to invade the teat cistern. If an infection is established inflammatory reac-tions will occur in the udder.

Comparison of some screening tests for detecting mastitis

Quarter milk samples were analyzed for somatic cell counts, ATP, NAGase, bovine serum albumin, antitrypsin, conductivity, and bacteriological findings. The diagnostic tests were compared with respect to their ability to predict the infection status of a quarter on test day. Predictive ability was evaluated by logistic regression. All components measured increased in the presence of infection. Correlations between components were higher in quarters with pathogens than in quarters free from infection. Predictive ability was highest for ATP, somatic cell counts, and NAGase. Comparisons within udder using ratios from different quarters gave no better prediction than absolute values. For all diagnostic tests except conductivity, combinations of absolute values and interquarter ratios were not better than predictions based on absolute values only. If conductivity is to be used to predict infection status, a combination of absolute value and interquarter evaluation is recommended. Combinations of two diagnostic tests increased the predictive ability in most cases, although the increase was only minor.

Extraction and determination of adenosine 5'-triphosphate in bovine milk by the firefly luciferase assay

The release of ATP from somatic cells in milk with the detergent Triton X-100 was optimized for assay with firefly luciferase. A small volume of milk (40 microliters) is added to 0.8 ml of 0.2% Triton X-100 in 100 mM Tris, 4 mm EDTA, pH 7.8. After approximately 1 min, 0.2 ml of luciferase reagent is added and the emission of light is measured in a luminometer. Results are calibrated with an ATP standard. This single method gave high yields of ATP from somatic cells in milk without interference from bacterial ATP. Extracts could be stored or transported prior to assay without deterioration of results. A close correlation was found between somatic cell count and ATP in milk samples collected at a farm as well as in milk samples from a cow with experimental mastitis. Results are promising for future use for diagnosis of mastitis but further work and field testing has to be done before it can be used on a wider scale.

[Serratia-mastitis in cows as a herd problem]

Clinical mastitis with infection of Serratia marcescens occurred in a tied-up dairy herd in Sweden on a scale widely exceeding what has hitherto been reported in veterinary literature. The herd contained 37 milking cows before the disease period but only 14 at slaughter 21 months later in spite of some recruitment. A very large number of mastitis cases, usually rather mild and of short duration, had then occurred--during one single month not less than 47 cases. Hardly any cow escaped the disease. Instead, the single cows fell ill at short intervals with mastitis in the same quarter as previously or in another quarter. Antibiotic therapy in clinical cases, dry cow therapy and teat dipping had no obvious effect. Serratia marcescens was isolated in all 14 slaughtered cows in one or more quarters. The morphological changes were remarkably mild. Isolated Serratia strains revealed no distinctive marks compared with ordinary saprophytic strains in laboratory tests. Serratia-contaminated sawdust used as litter was possibly the source of infection and the milking machine possibly the tool for the transmission of bacteria to the udder, in the latter case by the aspiration of contaminated sawdust when the claw was attached or detached, or it fell off during milking. The pathogenicity of the bacteria and the susceptibility of the cows to udder infection may have been increased.

The interference between coagulase negative staphylococci and Corynebacterium bovis and the common udder pathogens in the lactating cow

In these experiments it was studied whether the presence of the low pathogenic coagulase negative staphylococci or Corynebacterium bovis in the lactating bovine udder would have a protective effect against some of the common udder pathogens such as Staphylococcus aureus, the streptococci and the Gram negative bacteria.

Characterization and response to mitogens of mammary lymphocytes from the bovine dry-period secretion

From bovine mammary secretion during the dry period, the total number of cells was between 1.2 and 5.9 X 10(6)/ml. A mean of 35% of these cells were classified as lymphocytes and approximately 85% of them could be isolated by the Ficoll-isopac method. Centrifugation separated 6% of the cells into the fat; 5% of them were lymphocytes. About 47% of the lymphocytes bound Helix pomatia agglutinin, a T-cells marker, while the proportion of Ig-bearing cells was approximately 28%. The mammary lymphocytes were stimulated by the lectins phytohaemagglutinin, pokeweed mitogen, concanavalin A and by lipopolysaccharide from Salmonella typhimurium. The stimulation indices of mammary lymphocytes were generally lower than those for peripheral blood lymphocytes from the same animals. The background values, i.e. counts/min of lymphocytes incubated without mitogen, were often higher for lymphocytes isolated from mammary secretion than from blood.

Occurrence and characterization of "avium-like" Mycobacteria isolated from animals in Sweden

431 cultures of "avium-like" mycobacteria (ALM) were isolated from wild and domestic animals during 1974--76 at the National Veterinary Institute, Stockholm. Of these, 50 isolates from pigs were studied by growth-chromogenicity, pathogenicity, and biochemical tests. Furthermore, thin-layer chromathography was performed, and on some isolates serotyping. All 50 isolates belonged to Runyon's group III and were pathogenic for chicken; none was capable of splitting oleic acid from Tween 80. 47 gave tellurite reduction within a period of three days; one was arylsulphatase-positive after three days and a further four after 14 days. The biological and biochemical tests permit assignation of the 50 isolates to the M. avium-intracellulare complex. The lipid patterns of the isolates examined were analysed by thin-layer chromatography. Thirty-five of the isolates showed a lipid pattern similar to that of A 2 of the fowl reference strain; three belonged to lipid type A 1 and four to A 3. Eight could not be typed. Of 22 isolates, 14 could be assigned to M. avium serotypes.

Biochemical characterization of unidentified microaerophilic cocci isolated from heifer and dry-cow mastitis

Thirty-nine strains of gram-positive microaerophilic cocci isolated from cases of heifer and dry-cow mastitis were biochemically characterized with the API 50E and API-ZYM test kit systems, gas-liquid chromatography for analysis of end products of glucose metabolism, and anaerobic biochemical tests (L. V. Holdeman, E. P. Cato, and W. E. C. Moore, Anaerobe Laboratory Manual, Virginia Polytechnic Institute, Blacksburg, 1977). Strains were screened for production of a variety of extracellular enzymes on substrate-containing agar plates and for hemolysin and coagulase production. Antibiotic susceptibility and sensitivity tests were also performed. The microaerophilic cocci displayed homogeneity with respect to the majority of the biochemical tests used; i.e., greater than or equal to 90% of the strains were consistently positive or negative in any one test and probably represent one species. All produced deoxyribonuclease, ribonuclease, and hyaluronidase, and 92% were positive for chondroitin sulfatase. Catalase and coagulase tests were negative. Greening was observed on bovine blood agar. Acetic and succinic acids were produced by all strains as the only detectable products of glucose metabolism. The strains were susceptible to penicillin G, cefoxitin, doxycycline, and chloramphenicol and were resistant to clindamycin, novobiocin, and metronidazole. Their taxonomic position remains unclear.

Phage heterogeneity of coagulase-negative staphylococci isolated in the United States and Sweden from bovine milk

A Swedish bovine and a Dutch human phage set for coagulase-negative staphylococci were used to phage type coagulase-negative staphylococci isolated from bovine milk from Minnesota dairy herds. A comparison was also made of the deoxyribonuclease activity of coagulase-negative staphylococci isolated from bovine milk in Sweden and Minnesota. Of 133 Minnesota isolates, only one could be typed with the Swedish set and one by the Dutch set, whereas of 218 Swedish strains, 49 could be typed with the Swedish set and 7 by the Dutch set. A larger number of coagulase-negative isolates from Sweden were deoxyribonuclease positive (35%) than were the similar isolates from Minnesota (12%). These findings substantiate the marked heterogeneity of coagulase-negative staphylococci isolated from bovine udders. Results presented point to the usefulness of establishing regional phage sets for epidemiological investigations of coagulase-negative staphylococci in cattle. It is anticipated that at a later stage the regional phage sets will be coordinated internationally.

Immunoglobulin-binding structure on bovine group G streptococci different from type III Fc receptors on human group G streptococci

The immunoglobulin G (IgG)-binding capacity of 54 group G streptococci of human and bovine origin was investigated. Of 20 human strains, 17 carried a surface component which could combine with human IgG and bovine IgG1 and IgG2. Inhibition experiments with unlabeled human IgG and with a panel of animal sera revealed that the same surface component was involved in the binding of human as well as bovine immunoglobulins. Of 16 beta-hemolytic bovine group G streptococci, 13 reacted with human IgG but not with bovine IgG1 or IgG2. This binding structure was different from the type III Fc reactivity found in human group G streptococci. All human strains, including the three IgG Fc-nonreactive strains, fermented trehalose, in contrast to all bovine beta-hemolytic strains, which were negative. Immunoglobulin Fc reactivity is thus a feature not only of human strains but also of some bovine strains.

Phage typing of coagulase-negative staphylococci

218 bovine and 116 human strains of coagulase-negative staphylococci and 46 bovine Staphylococcus aureus strains were typed with the Verhoef-phage set for human staphylococci and the Holmberg-set for bovine staphylococci. 22.5% of the bovine strains were lysed by the bovine phages and only 3.2% by the human phages. None of the bovine Staph. aureus strains could be typed. 21% of the human strains tested were lysed by the human phages and only 5.2% by the bovine phages. These results clearly demonstrate the need of separate phage sets for the typing of bovine and human coagulase-negative staphylococci.

The invasiveness of Staphylococcus aureus and Staphylococcus epidermidis for the mammary gland of the mouse

The invasiveness of Staphylococcus aureus and Staphylococcus epidermidis for the mammary gland of the mouse was assessed by contaminating the damaged teats of suckling mice and sampling the mammary glands for the contaminating organism 48 hours later. Using this test system Staphylococcus aureus strain BB invaded 17 of 40 glands (42.5 %) and Staphylococcus epidermidis strain 279 invaded 2 of 40 glands (5.0 %). The histopathological changes in glands infected with Staphylococcus aureus were more severe than in those infected with Staphylococcus epidermidis.