Gene network-based and ensemble modeling-based selection of tumor-associated antigens with a predicted low risk of tissue damage for targeted immunotherapy

BACKGROUND

Tumor-associated antigens and their derived peptides constitute an opportunity to design off-the-shelf mainline or adjuvant anti-cancer immunotherapies for a broad array of patients. A performant and rational antigen selection pipeline would lay the foundation for immunotherapy trials with the potential to enhance treatment, tremendously benefiting patients suffering from rare, understudied cancers.

METHODS

We present an experimentally validated, data-driven computational pipeline that selects and ranks antigens in a multipronged approach. In addition to minimizing the risk of immune-related adverse events by selecting antigens based on their expression profile in tumor biopsies and healthy tissues, we incorporated a network analysis-derived antigen indispensability index based on computational modeling results, and candidate immunogenicity predictions from a machine learning ensemble model relying on peptide physicochemical characteristics.

RESULTS

In a model study of uveal melanoma, Human Leukocyte Antigen (HLA) docking simulations and experimental quantification of the peptide-major histocompatibility complex binding affinities confirmed that our approach discriminates between high-binding and low-binding affinity peptides with a performance similar to that of established methodologies. Blinded validation experiments with autologous T-cells yielded peptide stimulation-induced interferon-γ secretion and cytotoxic activity despite high interdonor variability. Dissecting the score contribution of the tested antigens revealed that peptides with the potential to induce cytotoxicity but unsuitable due to potential tissue damage or instability of expression were properly discarded by the computational pipeline.

CONCLUSIONS

In this study, we demonstrate the feasibility of the de novo computational selection of antigens with the capacity to induce an anti-tumor immune response and a predicted low risk of tissue damage. On translation to the clinic, our pipeline supports fast turn-around validation, for example, for adoptive T-cell transfer preparations, in both generalized and personalized antigen-directed immunotherapy settings.

Breaking barriers: NEK2 inhibition shines in multiple myeloma treatment

In their article, Cheng et al.1 reveal that NEK2 loss reshapes the tumor microenvironment, reducing tumor-associated macrophages and decreasing T cell exhaustion. They show that this ultimately favors the immune system's anti-cancer response in multiple myeloma.

Melanoma 2.0. Skin cancer as a paradigm for emerging diagnostic technologies, computational modelling and artificial intelligence

We live in an unprecedented time in oncology. We have accumulated samples and cases in cohorts larger and more complex than ever before. New technologies are available for quantifying solid or liquid samples at the molecular level. At the same time, we are now equipped with the computational power necessary to handle this enormous amount of quantitative data. Computational models are widely used helping us to substantiate and interpret data. Under the label of systems and precision medicine, we are putting all these developments together to improve and personalize the therapy of cancer. In this review, we use melanoma as a paradigm to present the successful application of these technologies but also to discuss possible future developments in patient care linked to them. Melanoma is a paradigmatic case for disruptive improvements in therapies, with a considerable number of metastatic melanoma patients benefiting from novel therapies. Nevertheless, a large proportion of patients does not respond to therapy or suffers from adverse events. Melanoma is an ideal case study to deploy advanced technologies not only due to the medical need but also to some intrinsic features of melanoma as a disease and the skin as an organ. From the perspective of data acquisition, the skin is the ideal organ due to its accessibility and suitability for many kinds of advanced imaging techniques. We put special emphasis on the necessity of computational strategies to integrate multiple sources of quantitative data describing the tumour at different scales and levels.

Single-Molecule RNA Sequencing Reveals IFNγ-Induced Differential Expression of Immune Escape Genes in Merkel Cell Polyomavirus-Positive MCC Cell Lines

Merkel cell carcinoma (MCC) is a rare and highly aggressive cancer, which is mainly caused by genomic integration of the Merkel cell polyomavirus and subsequent expression of a truncated form of its large T antigen. The resulting primary tumor is known to be immunogenic and under constant pressure to escape immune surveillance. Because interferon gamma (IFNγ), a key player of immune response, is secreted by many immune effector cells and has been shown to exert both anti-tumoral and pro-tumoral effects, we studied the transcriptomic response of MCC cells to IFNγ. In particular, immune modulatory effects that may help the tumor evade immune surveillance were of high interest to our investigation. The effect of IFNγ treatment on the transcriptomic program of three MCC cell lines (WaGa, MKL-1, and MKL-2) was analyzed using single-molecule sequencing via the Oxford Nanopore platform. A significant differential expression of several genes was detected across all three cell lines. Subsequent pathway analysis and manual annotation showed a clear upregulation of genes involved in the immune escape of tumor due to IFNγ treatment. The analysis of selected genes on protein level underlined our sequencing results. These findings contribute to a better understanding of immune escape of MCC and may help in clinical treatment of MCC patients. Furthermore, we demonstrate that single-molecule sequencing can be used to assess characteristics of large eukaryotic transcriptomes and thus contribute to a broader access to sequencing data in the community due to its low cost of entry.

The IKZF1-IRF4/IRF5 Axis Controls Polarization of Myeloma-Associated Macrophages

The bone marrow niche has a pivotal role in progression, survival, and drug resistance of multiple myeloma cells. Therefore, it is important to develop means for targeting the multiple myeloma bone marrow microenvironment. Myeloma-associated macrophages (MAM) in the bone marrow niche are M2 like. They provide nurturing signals to multiple myeloma cells and promote immune escape. Reprogramming M2-like macrophages toward a tumoricidal M1 phenotype represents an intriguing therapeutic strategy. This is especially interesting in view of the successful use of mAbs against multiple myeloma cells, as these therapies hold the potential to trigger macrophage-mediated phagocytosis and cytotoxicity. In this study, we observed that MAMs derived from patients treated with the immunomodulatory drug (IMiD) lenalidomide skewed phenotypically and functionally toward an M1 phenotype. Lenalidomide is known to exert its beneficial effects by modulating the CRBN-CRL4 E3 ligase to ubiquitinate and degrade the transcription factor IKAROS family zinc finger 1 (IKZF1). In M2-like MAMs, we observed enhanced IKZF1 levels that vanished through treatment with lenalidomide, yielding MAMs with a bioenergetic profile, T-cell stimulatory properties, and loss of tumor-promoting capabilities that resemble M1 cells. We also provide evidence that IMiDs interfere epigenetically, via degradation of IKZF1, with IFN regulatory factors 4 and 5, which in turn alters the balance of M1/M2 polarization. We validated our observations in vivo using the Crbn^I391V mouse model that recapitulates the IMiD-triggered IKZF1 degradation. These data show a role for IKZF1 in macrophage polarization and can provide explanations for the clinical benefits observed when combining IMiDs with therapeutic antibodies.See related Spotlight on p. 254.

Mathematical Modelling in Biomedicine: A Primer for the Curious and the Skeptic

In most disciplines of natural sciences and engineering, mathematical and computational modelling are mainstay methods which are usefulness beyond doubt. These disciplines would not have reached today's level of sophistication without an intensive use of mathematical and computational models together with quantitative data. This approach has not been followed in much of molecular biology and biomedicine, however, where qualitative descriptions are accepted as a satisfactory replacement for mathematical rigor and the use of computational models is seen by many as a fringe practice rather than as a powerful scientific method. This position disregards mathematical thinking as having contributed key discoveries in biology for more than a century, e.g., in the connection between genes, inheritance, and evolution or in the mechanisms of enzymatic catalysis. Here, we discuss the role of computational modelling in the arsenal of modern scientific methods in biomedicine. We list frequent misconceptions about mathematical modelling found among biomedical experimentalists and suggest some good practices that can help bridge the cognitive gap between modelers and experimental researchers in biomedicine. This manuscript was written with two readers in mind. Firstly, it is intended for mathematical modelers with a background in physics, mathematics, or engineering who want to jump into biomedicine. We provide them with ideas to motivate the use of mathematical modelling when discussing with experimental partners. Secondly, this is a text for biomedical researchers intrigued with utilizing mathematical modelling to investigate the pathophysiology of human diseases to improve their diagnostics and treatment.

Network- and systems-based re-engineering of dendritic cells with non-coding RNAs for cancer immunotherapy

Dendritic cells (DCs) are professional antigen-presenting cells that induce and regulate adaptive immunity by presenting antigens to T cells. Due to their coordinative role in adaptive immune responses, DCs have been used as cell-based therapeutic vaccination against cancer. The capacity of DCs to induce a therapeutic immune response can be enhanced by re-wiring of cellular signalling pathways with microRNAs (miRNAs). Methods: Since the activation and maturation of DCs is controlled by an interconnected signalling network, we deploy an approach that combines RNA sequencing data and systems biology methods to delineate miRNA-based strategies that enhance DC-elicited immune responses. Results: Through RNA sequencing of IKKβ-matured DCs that are currently being tested in a clinical trial on therapeutic anti-cancer vaccination, we identified 44 differentially expressed miRNAs. According to a network analysis, most of these miRNAs regulate targets that are linked to immune pathways, such as cytokine and interleukin signalling. We employed a network topology-oriented scoring model to rank the miRNAs, analysed their impact on immunogenic potency of DCs, and identified dozens of promising miRNA candidates, with miR-15a and miR-16 as the top ones. The results of our analysis are presented in a database that constitutes a tool to identify DC-relevant miRNA-gene interactions with therapeutic potential (https://www.synmirapy.net/dc-optimization). Conclusions: Our approach enables the systematic analysis and identification of functional miRNA-gene interactions that can be experimentally tested for improving DC immunogenic potency.

Curatopes Melanoma: A Database of Predicted T-cell Epitopes from Overly Expressed Proteins in Metastatic Cutaneous Melanoma

Therapeutic anticancer vaccination has been adapted as an immunotherapy in several solid tumors. However, the selection of promising candidates from the total quantity of possible epitopes poses a challenge to clinicians and bioinformaticians alike, and very few epitopes have been tested in experimental or clinical settings to validate their efficacy. Here, we present a comprehensive database of predicted nonmutated peptide epitopes derived from genes that are overly expressed in a group of 32 melanoma biopsies compared with healthy tissues and that were filtered against expression in a curated list of survival-critical tissues. We hypothesize that these "self-tolerant" epitopes have two desirable properties: they do not depend on mutations, being immediately applicable to a large patient collective, and they potentially cause fewer autoimmune reactions. To support epitope selection, we provide an aggregated score of expected therapeutic efficiency as a shortlist mechanism. The database has applications in facilitating epitope selection and trial design and is freely accessible at https://www.curatopes.com. SIGNIFICANCE: A database is presented that predicts and scores antitumor T-cell epitopes, with a focus on tolerability and avoidance of severe autoimmunity, offering a supplementary epitope set for further investigation in immunotherapy.

Agreement among equine veterinarians and between equine veterinarians and inertial sensor system during clinical examination of hindlimb lameness in horses

BACKGROUND

Hindlimb lameness evaluation is known to be challenging. Experience is essential for the ability of equine veterinarians to detect lameness. Nevertheless, even an experienced veterinarian is still subject to bias. Objective lameness detecting methods have been established to aid veterinarians.

OBJECTIVES

1) To estimate the effect of experience on the interobserver agreement and the agreement between a body-mounted inertial sensor system (BMISS) and veterinarians on detecting hindlimb lameness, and 2) to estimate the agreement between the BMISS and highly experienced veterinarians on change in lameness after diagnostic analgesia.

STUDY DESIGN

Cross-sectional study.

METHODS

Twenty-six horses with hindlimb lameness were evaluated in clinical conditions by clinicians and simultaneously measured by the BMISS. Videos of their lameness examination were recorded and shown to 13 veterinarians from three groups of varying experience for evaluation. The interobserver agreement and the agreement between veterinarians and the BMISS were calculated.

RESULTS

Interobserver agreement from all three groups was recorded as 'fair'. The strength of agreement between veterinarians and BMISS was 'fair' for the highly experienced group, 'slight to fair' for the moderately experienced group and 'slight' in the inexperienced group. The BMISS and the highly experienced veterinarians declared a 'strong' agreement in assigning an improvement in lameness after diagnostic analgesia.

MAIN LIMITATIONS

Lameness evaluation through video viewing might be more challenging for some evaluators than live situations.

CONCLUSIONS

Given the task of evaluating videos of horses trotting in a straight line, the more experienced veterinarians did not show more reliability than those with less experience. Due to 1) the moderate agreement between the BMISS and clinicians (highly experienced and moderately experienced) in the live clinical evaluation in determining hindlimb lameness, and 2) the strong association between the BMISS and highly experienced veterinarians in determining improvement of lameness after anaesthesia, therefore the use of the BMISS as a supporting tool for veterinarians is encouraged.

Dendritic cell vaccination in metastatic uveal melanoma as compassionate treatment: Immunological and clinical responses

e21024

Background: Other than cutaneous melanoma, metastatic uveal melanoma (UM) is minimally responsive to checkpoint inhibitors. The prognosis remains very poor with mortality rates nearly unchanged over the last decades. The recently growing insight that immunotherapy significantly improves outcomes for cancer patients led to a re-emergence of vaccines including dendritic cell (DC) vaccines. Methods: We vaccinated an UM patient in a compassionate use setting and assessed the immunological and clinical responses. Based on this experience we performed individual compassionate treatments in other UM patients using DC loaded by peptide pulsing and/or mRNA transfection (autologous tumor RNA or RNA coding for tumor antigens). Results: The first patient was vaccinated in 2013 after a liver metastasis was resected and checkpoint blockade with ipilimumab was started. In 2014 the patient showed progression in the liver. We continued DC vaccination in shorter intervals and adapted antigen loading (with mRNA coding for an individual GNAQ driver mutation) accompanied by a further cycle of ipilimumab. Therapy resulted in complete remission of liver metastases, but the patient developed new skin metastases. Again the loading of DC was adapted (peptides of passenger mutations predicted after Next-Generation Sequencing) and infusions with pembrolizumab were started. Pathology from some regressing lesions showed a massive T cell infiltration and in parallel GNAQ mutation-specific T cells could be found in the patient’s blood. Skin metastases regressed and the patient is now free of detectable tumor after 65 months. Immune monitoring in the patient’s blood showed a vaccine-induced functional T cell response against the QNAQ-driver mutation. Three of other four patients are also still alive, one in complete remission under DC vaccination in combination with pembrolizumab, two of them showing measurable disease, and one deceased disease related after 28 months, resulting in a median OS of the five patients of 36.4 months. Immune monitoring in one of those patients showed a CD4+ and CD8+ INF-gamma T cell response against the autologous tumor RNA vaccine. No grade 3 or 4 toxicity occurred. Conclusions: The observed prolonged median OS and the fact that 2/5 patients remain disease-free is definitely encouraging. Vaccination immunotherapy with antigen-laden DC is a potential therapeutic option for patients with metastatic uveal melanoma. Combinations with checkpoint inhibitors proved promising, and should be further evaluated in clinical trials.

Internal Fixation of Long Bone Fractures in Farm Animals

This study demonstrates that long bone fracture treatment in food and fibre producing animals is in most cases successful. The greatest disadvantage of such treatment are the costs of the surgery and implants.

Evaluation of a standardised radiographic technique of the equine hoof

Radiography of the equine hoof is often used to obtain a diagnosis. Quantitative interpretation, especially for research purposes requires high quality and accuracy of radiographs. The purpose of this study was to describe and evaluate a radiographic technique for the lateromedial (LM) and the dorsopalmar (DP) view of the equine hoof. Ten radiographs for each view from one cadaver limb and from both front feet in a standing horse were taken in order to assess repeatability of the radiographic technique. The method requires easy to use adjustable and portable equipment and strictly defined external radio opaque markers on the hoof capsule. The digitalised radiographs were processed and analysed with the software package Metron PX, measuring 13 parameters in the LM view and 10 parameters in the DP view, respectively. Results show that with few exceptions measurements of these parameters revealed a coefficient of variation that was smaller than 0.05. It was concluded that this easy to use standardised radiographic technique ensures excellent accuracy and repeatability for both the LM and DP view. Hence, this method provides an adequate tool for quantitative assessment of the equine hoof, inter- and intraindividually.

Surgical management of complete diaphyseal third metacarpal and metatarsal bone fractures: clinical outcome in 10 mature horses and 11 foals

REASONS FOR PERFORMING STUDY

Osteosynthesis of third metacarpal (McIII) and third metatarsal (MtIII) bone fractures in horses is a surgical challenge and complications surrounding the repair are common. Retrospective studies evaluating surgical repair, complications and outcome are necessary to increase knowledge and improve success of long bone fracture repair in the horse.

OBJECTIVES

To evaluate clinical findings, surgical repair, post operative complications and outcome of 10 mature horses and 11 foals with McIII or MtIII fractures that were treated with open reduction and internal fixation (ORIF).

METHODS

Medical records were reviewed and follow-up information obtained by means of radiographs and/or telephone questionnaire.

RESULTS

Survival was achieved in 62% of the horses (3 mature/10 foals). On long-term evaluation (> 6 months) 11 horses (2 mature/9 foals) were fit for their intended activity, one mature horse had a chronic low grade lameness, and one foal was lost to follow-up because it was sold. The main fracture types were simple transverse (333%) or simple oblique (28.6%) and 71.4% of the fractures were open, 3 Type I (one mature/2 foals) and 12 type II (7 mature/5 foals). The preoperative assessment revealed inadequate emergency treatment in 10 horses (5 mature/5 foals; 47.6%). Survival rate of horses with open fractures was 12.5% (1/8) in mature and 85.7% (6/7) in foals. Post operative incisional infection (4 mature, 3 foals) was only managed successfully in 2 foals. Fracture instability related to inadequate fracture fixation technique occurred in 4 horses (all mature) and was always associated with unsuccessful outcome.

CONCLUSIONS

Age, bodyweight and infection are strongly associated with outcome in treatment of complete McIII/MtIII fractures.

CLINICAL RELEVANCE

Rigid fixation using plates and screws can be successful in treatment of closed or open, complete diaphyseal McIII/MtIII fractures in mature horses and foals. Instable fixation, infection and a bodyweight > 320 kg are major risk factors for unsuccessful outcome.

Ileal impaction in 22 cows

The clinical signs, diagnosis, treatment and outcome of 22 cows with ileal impaction were investigated using the medical records of bovine patients referred to the Department of Farm Animals, Vetsuisse Faculty, University of Zurich from 1993 to 2003. Only 15 of the cows had signs of colic, which were subtle but slowly increased in severity in some patients. The results of haematological and biochemical analyses were mildly abnormal in only few animals. There was no correlation between the duration of the disorder before admission, the severity of symptoms and the results of the haematological and biochemical analyses. Dilated loops of small intestine in the right dorsal quadrant of the abdomen could be palpated transrectally and imaged via ultrasonography. A definitive diagnosis of ileal impaction was made during exploratory laparotomy by finding the impaction and ruling out other abnormalities. In 19 cows, the obstructing food mass was easily massaged into the caecum, and in three animals an enterotomy was carried out. All cows had an uneventful recovery with no recurrence of the disorder. It is concluded that the cause of the impaction was most likely due to seasonal influences and winter-feeding with a hay based ration. The short and long-term prognosis after surgical intervention was good.

[Do hoof cracks represent a superficial hoof-problem?]

Fifty-four horses with hoof cracks were referred to the Equine Hospital of the University of Zurich, for treatment. The horses were admitted because of lameness or other symptoms caused by the cracks. Deep or complicated quarter cracks were the most common type of cracks diagnosed. Poor conformation and abnormal hoof shape were the most important causes of hoof crack development, whereas injury to the coronary band was a less frequently encountered cause. Effective treatment of this problem includes corrective shoeing, removing horn from the weight-bearing surface as well as from the crack with a Dremel tool and immobilization of the borders of the crack. However, even with such a therapy, the recurrence rate of hoof cracks was with 20% very high.

Ultrasonographic findings in cows with dilatation, torsion and retroflexion of the caecum

Thirty cows with caecal dilatation underwent clinical and ultrasonographic examinations, followed by a right flank laparotomy and surgical correction. The intraoperative findings were compared with the results of the ultrasonographic examination. The appearance, position, dimensions, diameter and nature of the contents of the caecum and proximal and spiral ansa of the colon were determined with a 3.5 MHz linear transducer. The wall of the proximal ansa of the colon and of the dilated caecum closest to the abdominal wall was visible in all the cows and appeared as an echogenic semicircular line immediately adjacent to the peritoneum. The contents of the caecum and of the proximal and spiral ansa of the colon were not visible in 21, 25 and 25 cows, respectively, owing to gas. In the remaining cows, the contents were hypoechogenic to echogenic in appearance. In all of the cows, the dilated caecum was imaged from the right abdominal wall at the level of the tuber coxae. The caecum was imaged from the 12th, 11th and 10th intercostal spaces in 11, five and three cows, respectively. The caecum and proximal ansa of the colon were situated immediately adjacent to the right abdominal wall in 28 cows, but in the other two cows parts of these structures were pushed away from the abdominal wall by the liver or gall bladder. The diameter of the caecum, measured at various sites varied from 7.0 to 25.0 cm. Caecal dilatation was diagnosed on the basis of the results of rectal examinations in 28 of the cows, but in all 30 cows on the basis of the results of the ultrasonographic examinations. Dilatation and caudal displacement of the caecum were diagnosed in 18 cows; dilatation and cranioventral retroflexion of the caecum were diagnosed in six cows, and dilatation and craniodorsal retroflexion of the caecum were diagnosed in two cows. In the four other cows, the direction of the retroflexed caecum could not be determined. The diagnosis of caecal dilatation based on the ultrasonographic findings was confirmed in all the cows during exploratory laparotomy. The results of ultrasonography and exploratory surgery with regard to the position of the dilated and sometimes retroflexed or twisted caecum were in complete agreement in 18 cases, in partial agreement in eight cases, but in four cases did not agree.

Semen characteristics after vasectomy in the ram

The objective of this study was to monitor the changes in semen characteristics in vasectomized rams and to determine if infertility was present 14 days after vasectomy. Experiments were performed using five cross-breed rams, aged between 18 and 30 months. Semen was collected weekly by artificial vagina from 2 months before to 5 months after vasectomy. After sexual rest for 10 days, vasectomy was performed by the cranial midscrotal approach. In all ejaculates the volume, concentration, total sperm number, motility and morphology (normal spermatozoa, loose heads) were determined and sperm viability (SYBR-14/PI) was evaluated in all semen samples collected after vasectomy. In the first ejaculate obtained 14 days post vasectomy all rams showed a significant (P < 0.05) drop in mean volume (from 1.2 to 0.5 mL), total sperm count (from 5176.8 to 51.1 x 10(6)) and morphologically normal sperm (from 84.1 to 15.7%), when compared to the last prevasectomy collection. We could also demonstrate a positive correlation (r = 0.89) between the individual cumulative total number of spermatozoa after vasectomy and the scrotal circumference measured before vasectomy. Sperm motility and viability could never be demonstrated after vasectomy and normal spermatozoa continuously decreased concomitant with an increase in loose heads. On post mortem examination 5 months after surgery, spermatocele formation and multiple sperm granulomas were present in all five rams. Our results show that in the first ejaculate collected by artificial vagina 14 days after vasectomy, no motile and viable spermatozoa could be detected. Despite weekly collections during a 5-month period after sterilization, azoospermia could never be achieved.

Strangulation of the duodenum by the uterus during late pregnancy in two cows

Two Swiss Braunvieh cows in late pregnancy underwent surgery because of a rare form of ileus due to strangulation of the duodenum at its caudal flexure by the gravid uterus. The whole uterus had passed through a gap between the mesoduodenum and duodenum and with increasing weight had led to strangulation of the duodenum. This was possible since the mesoduodenum and both walls of the greater omentum adjacent to its caudal edge were not connected with the duodenum, probably due to a congenital inhibitory malformation. A transsection and an end-to-end anastomosis of the duodenum were necessary in both cases since it was impossible to retract the gravid uterus through the defect. Postoperative recovering was uneventful in both cows, which were discharged after seven and five days respectively and calved normally about two months later.

[Extracorporal shock wave therapy in veterinary medicine]

This article gives a general overview on a new therapy in equine orthopedics. In human medicine extracorporal shock wave therapy (ESWT) is used for lithotripsy of stones of the urologic system and also in orthopedics. In equine medicine the therapy is almost exclusively applied for the treatment of orthopedic problems. The main indications are proximal suspensory desmitis (PSD), lesions of tendons and ligaments, osteoporotic changes and spavin. In this paper the mode of action of shock waves and the different shock wave devices are discussed. Also, some information about an ongoing clinical trial at the Animal Hospital University of Zürich is given.

[Hydrosalpinx in a goat]

A two year old Swiss Alpine goat was referred to our clinic because of sterility. Ultrasound examination revealed a nonechogenic area cranially to the urinary bladder. As hydrometra was suspected, the goat was treated repeatedly with PGF2 alpha. Success of this therapy, however, was unsatisfactory and estrus was therefore induced by progesterone in combination with eCG and the goat mated. As conception failed and ultrasonography remained unchanged, laparoscopy was performed and a fluid filled structure could be located in the region of the right oviduct. After ovariohysterectomy and histo-pathological examination of the genital organs hydrosalpinx was diagnosed on both sides.

Evidence for a parasite-mediated inhibition of abomasal acid secretion in sheep infected with Ostertagia leptospicularis

The acid secretory capacity of the abomasal mucosa was studied in sheep experimentally infected with Ostertagia leptospicularis. The acidity of the abomasal contents, permanently recorded by a pH probe located inside the abomasum, decreased markedly to mean levels between pH 5 and 6. Subcutaneous administration of histamine or carbachol successfully stimulated acid secretion (pH 3.4). The results indicate that the abomasal mucosa harboured a population of functional parietal cells which were also identified immunohistochemically (H(+)/K(+)-ATPase). Ultrastructural investigation before stimulation revealed that the majority of these cells was in a resting state. Despite high serum gastrin levels, the acid secretion was blocked either at the level of the parietal cell or the enterochromaffin-like cell by an unknown factor, possibly mediated by the parasites. This is the first report of a parietal cell dysfunction associated with a nematode infection in the abomasum. It is suggested that the parasites induce changes in their environment which favour their survival and/or increase their reproduction.

Imaging findings in a cow with a retropharyngeally displaced magnet

This report describes the ultrasonographic and radiographic findings and the treatment of a Swiss Brown cow with a retropharyngeal abscess caused by improper administration of a magnet.

Ultrasonographic findings in five cows before and after treatment of reticular abscesses

Five cows with reticular abscesses were examined clinically, haematologically, radiographically and ultrasonographically. They all had clinical signs typical of traumatic reticuloperitonitis, including chronic indigestion, pyrexia, an absence of or reduced ruminal motility, weight loss and a positive reaction to foreign body test. A haematological examination revealed anaemia, increased concentrations of plasma protein and fibrinogen and a decreased clotting time in the glutaraldehyde test. On the basis of the radiographic examination, a tentative diagnosis of reticular abscess was made in four of the cows, because the reticulum was displaced from the peritoneum or because there was an extensive gas-fluid interface in the reticular region. By ultrasonography, a large reticular abscess with a well developed capsule was visible in each of the cows. The abscess was located between the reticulum and ventral peritoneum in two of them, between the reticulumn and right thoracic wall in two and between the reticulum and spleen in the other cow. A foreign body penetrating the abscess could be visualised ultrasonographically in one cow. In two cows, the abscesses were drained through an ultrasound-guided transcutaneous incision. In the other three cows, the abscess was incised and drained from within the reticulum during a rumenotomy. Ultrasonographic examination revealed that the abscess had been completely evacuated in four cows, but only by about two-thirds in the remaining cow. All the cows were clinically healthy when they were discharged.

[Congenital bile duct cysts and liver fibrosis in a foal]

A three-week-old foal was submitted to the clinic because of a minor traumatic injury at the lower jaw. At admission the foal exhibited diarrhea, a distended abdomen and reduced general condition. These findings could not be associated with the injury. On abdominal radiography decreased abdominal detail and a dorsocaudal displacement of the intestine was present. Ultrasonographically multiple fluid-filled cystic structures of several centimeters in diameter were identified. These cystic structures appeared to be associated with the liver. At laparotomy and at necropsy the liver was markedly enlarged and firm and had large, thin-walled, with a bile-like fluid filled cysts, 4-20 centimeters in diameter. Histological lesions were characterized by proliferation of small bile ducts and of interlobular connective tissue as well as focal subacute cholangitis. Gross and histological findings were considered to be consistent with congenital polycystic liver disease and fibrosis with ascending cholangitis.

[Laminitis in cattle: a literature review]

Worldwide afflictions of the claws belong to the economically important diseases in dairy cattle. The significance of laminitis has gained importance in the last years since the condition is regarded as the most important predisposing factor for the development of lesions such as sole ulcer, white line disease and heel horn erosion. Apart from the clinical stages (acute, subacute, chronic, chronic-recurrent) there is also a subclinical form of laminitis which does not cause lameness. It is characterized by soft yellowish sole and heel horn with haemorrhages in the sole and along the white line. Laminitis is a multifactorial event in which nutrition, genetic disposition and the perinatal period, combined with the associated diseases of high-yielding cows, have a particular significance. Currently, two principally different hypotheses on the pathogenesis are discussed. The generally accepted theory bases on a disturbance in the microcirculation of the corium. According to the other theory the circulatory disturbances are secondary to changes which occur in the horn producing cells of the stratum basale of the epidermis. The predisposing factors and the pathogenesis of laminitis are discussed in the light of possible therapeutic and prophylactic measures.