Development of a Web App to Convert Blood Insulin Concentrations among Various Immunoassays Used in Horses

The measurement of the blood insulin concentration, and comparison to cut-offs, is essential in diagnosing insulin dysregulation, a common equine endocrinopathy. However, different insulin assays provide disparate results. We aimed to ease comparison between assays by compiling original and published data into a web app to convert insulin measurements from one assay to another. Data were available for ADVIA Centaur insulin chemiluminescent immunoassay (CLIA), Beckman Coulter insulin radioimmunoassay (RIA), Immulite 1000 CLIA, Immulite 2000 CLIA, Immulite 2000 XPi CLIA, Mercodia equine insulin enzyme-linked immunosorbent assay (ELISA), and Millipore porcine insulin RIA. Linear models were fitted for 13 assay pairs using non-decreasing splines, and integrated into this app. Assay comparisons including data from several studies showed a lower performance. This indicates technical variation between laboratories, which has not been described before, but is relevant when diagnostic measurements and cut-offs are provided by different laboratories. Nevertheless, the models' overall high performance (median r2 = 0.94; range 0.57-1.00) supports their use to interpret results from diagnostic insulin measurements when the reference assay is unavailable, and to compare values obtained from different assays.

Periodontal structures in horses with pituitary pars intermedia dysfunction: A histological evaluation

Introduction

Pituitary pars intermedia dysfunction (PPID) and dental disorders are of major concern in horses older than 15 years. Although PPID in geriatric horses and dental disorders in all age groups are well described, a connection between this endocrine disease and pathological changes in equine dental structures has not yet been investigated. In humans, periodontitis is considered to be a complication of systemic diseases like diabetes mellitus type 2, obesity and various conditions leading to an impaired immune response. In PPID, cross links to insulin and immune dysregulations are proven. The aim of this study was to compare histological findings of the gingiva and the sub gingival periodontal ligament of PPID affected horses with control horses.

Methods

In a case-control morphometric descriptive study, 145 dental locations of 10 PPID affected horses (27.3 ± 2.06 years) were compared with 147 dental locations of 10 controls (21.4 ± 4.12 years). Histological parameters were leukocyte infiltration, keratinization of gingival epithelium, blood vessel supply of the periodontium and structure of cementum.

Results

The distribution and localization of gingival leukocyte infiltrations (LI) in PPID affected horses was more often multifocal to coalescing (p = 0.002) and reached into deeper parts of the periodontium, sometimes down to the sub gingival periodontal ligament (PDL). Aged animals of both groups showed higher prevalence (PPID: OR 1.66; controls: OR 1.15) for severe leukocyte infiltration in the PDL. PPID was not significantly associated with increased LI. The cementum bordering the soft tissue in interdental locations showed four times more irregularities in PPID affected horses than in controls which predisposes for interdental food impaction and periodontal diseases.

Discussion

In summary, multifocal to coalescing leukocytes and irregular cementum are seen more often in PPID than in controls - however our findings mainly reflect an association of older age with periodontal disease.

The Gingiva of Horses With Pituitary Pars Intermedia Dysfunction: A Macroscopic Anatomical Evaluation

Pituitary pars intermedia dysfunction (PPID) is a common neurodegenerative disease mainly in horses older than 15 years. The domestic equine population is following the same demographic change as that seen in humans; it is aging and veterinarians are asked to attend to geriatric horses more frequently. Common problems seen regularly in older equines are dental disorders and especially periodontal disease. As a systemic and endocrine disease, associated with delayed wound healing and impaired immune function, PPID should be considered before major dental treatment in aged equines is started. Possible negative effects of PPID on epithelial tissues could also affect the periodontium. Therefore, the aim of the present study was to identify gross changes in the gingiva associated with PPID. Fourteen horses with clinical signs of PPID and adenoma in the pituitary pars intermedia and 13 controls showing neither clinical signs nor PPID-associated histological changes in the pituitary gland were included. PPID-affected horses (26.9 ± 0.73 years) were significantly older than controls (20.0 ± 1.24 years). In the PPID-affected group, significantly more often an irregular and bulky appearance of the gingival texture was observed, as well as an irregular shape of the gingival margin. Furthermore, the sulcus gingivalis of cheek teeth frequently was deeper than 1 mm. These findings indicate a possible association between age, soft tissue alterations, and PPID and suggest a potential predisposition of PPID-affected horses for periodontal diseases.

[Therapy of bullous pemphigoid in a Warmblood gelding]

A 15-year-old Warmblood gelding was presented with multiple large, ulcerative, and crusty dermal lesions that had been existing for 4 years. Histopathology of a skin biopsy revealed cleft formation at the dermal-epidermal junction beneath the basal cells and above the basement membrane leading to the diagnosis of bullous pemphigoid. Immunosuppressive therapy with dexamethasone and azathioprine was initiated and after 14 weeks full remission of the ulcers was achieved. Scar tissue formation was evident in the areas of the formerly affected lesions. Following medication tapering over a period of 5 months, long-term therapy was continued with a maintenance dose of 0.5 mg/kg azathioprine daily. The ulcerative lesions recurred after 63 weeks of disease stabilization. Additionally, adverse drug reactions (acute laminitis and increased susceptibility to infections) were evident and the gelding was euthanized due to animal welfare considerations.

ECEIM consensus statement on equine metabolic syndrome

Equine metabolic syndrome (EMS) is a widely recognized collection of risk factors for endocrinopathic laminitis. The most important of these risk factors is insulin dysregulation (ID). Clinicians and horse owners must recognize the presence of these risk factors so that they can be targeted and controlled to reduce the risk of laminitis attacks. Diagnosis of EMS is based partly on the horse's history and clinical examination findings, and partly on laboratory testing. Several choices of test exist which examine different facets of ID and other related metabolic disturbances. EMS is controlled mainly by dietary strategies and exercise programs that aim to improve insulin regulation and decrease obesity where present. In some cases, pharmacologic aids might be useful. Management of an EMS case is a long‐term strategy requiring diligence and discipline by the horse's carer and support and guidance from their veterinarians.

A Fluorescent Benzo[g]isoquinoline-Based HIF Prolyl Hydroxylase Inhibitor for Cellular Imaging

Prolyl hydroxylation domain (PHD) enzymes catalyze the hydroxylation of the transcription factor hypoxia-inducible factor (HIF) and serve as cellular oxygen sensors. HIF and the PHD enzymes regulate numerous potentially tissue-protective target genes which can adapt cells to metabolic and ischemic stress. We describe a fluorescent PHD inhibitor (1-chloro-4-hydroxybenzo[g]isoquinoline-3-carbonyl)glycine which is suited to fluorescence-based detection assays and for monitoring PHD inhibitors in biological systems. In cell-based assays, application of the fluorescent PHD inhibitor allowed co-localization with a cellular PHD enzyme and led to live cell imaging of processes involved in cellular oxygen sensing.

[Thrombocytopenia in horses]

OBJECTIVE

The retrospective study aimed to evaluate the prevalence of true thrombocytopenia and ethylenediaminetetraacetic acid (EDTA)-induced pseudothrombocytopenia in horses and ponies and to assess the diagnostic and prognostic utility of true thrombocytopenia.

MATERIAL AND METHODS

In 3592 patients (2008-2015) hematological data (ADVIA® 2120, Siemens) were reviewed. Inclusion criteria were platelet counts < 90 x 109/l (EDTA-blood) and/or < 84 x 109/l (citrate blood). Thrombocytopenia was classified as true, EDTA-induced, and questionable. Patients with true thrombocytopenia were assigned to nine groups according to their history and four groups depending on the main diagnosis (inflammatory disorders, neoplasia, non-inflammatory intestinal disease, others). The frequencies of diagnoses were compared to the overall clinic population.

RESULTS

Thrombocytopenia was diagnosed in 123/3592 patients (3.4 %) and classified as true in 60/123 (49 %), EDTA-induced in 6/123 (5 %), and questionable in 57/123 (46 %) of cases. In true thrombocytopenia, the most common reasons for referral were lethargy (23/60, 38 %), fever (19/60, 32 %), and colic (17/60, 28 %). In these patients inflammation, neoplasia, non-inflammatory intestinal disease, and others were diagnosed in 25/60 (42 %), 11/60 (18 %), 10/60 (17 %), and 14/60 (23 %) of cases, respectively. Compared with the overall clinic population, there was an increased frequency of neoplasia (18 % versus 1 %). The mortality rate was significantly higher at 38 % in comparison with the overall population. Remarkably high mortality rates of 32 % and 82 % were observed in patients with inflammatory and neoplastic diseases, respectively.

CONCLUSION AND CLINICAL RELEVANCE

True thrombocytopenia is relatively rare in horses with internal medical conditions and should be verified by measurement in samples with citrate as anticoagulant. Thrombocytopenia is rarely the primary reason for referral and is a negative prognostic factor in neoplastic and inflammatory diseases.

Postoperative complications in equine elective, clean orthopaedic surgery with/without antibiotic prophylaxis

Objective: Retrospective analysis of postoperative complications in equines after clean, orthopaedic surgical procedures in order to detect differences between animals treated with antibiotics and horses without receiving these drugs. Material and methods: Details on 652 patients, surgical procedures and surgery-associated complications were compiled from horses being operated between June 2011 and January 2015. Antibiotic-receiving patients (n = 259) were tested for differences in complication rates and characteristics to controls (n = 393). Results: The total complication rate was 39.1 %. Increased swelling was observed most often (25.6 %), followed by exudation (7.5 %), fever without incisional alterations (2.3 %), suture dehiscence (1.8 %), and seroma (0.8 %). Seven patients (five treated, two controls) developed septic arthritis within a total of 463 arthroscopies (1.5 %). There were no significant differences in the development of postoperative complications, which were seen in 97/259 (37.5 %) antibiotic receiving patients and in 158/393 (40.2 %) controls. The application of perioperative antibiotics was significantly influenced by surgeon (p < 0.0001) and type of surgery (p = 0.0007) and increased with the number of surgical lesions (p = 0.03). In patients undergoing tendovaginoscopy/ bursoscopy, fasciotomy and neurectomy (n = 98), antibiotic prophylaxis was initiated less frequently than in other surgeries, e. g. combinations of surgeries, splint bone extraction, tenotomy, and arthroscopy (n = 554). Conclusion: Severe complications in equine clean orthopaedic surgery are rare and complication rates in patients either receiving perioperative antibiotics or not were not significantly different. Clinical relevance: Based on the results the use of antibiotics appears to be non-essential in uncomplicated elective orthopaedic interventions in the horse.

Adenokarzinom des Pankreas bei einem Warmblutwallach

Gegenstand und Ziel: Der Fallbericht geht auf die klinischen und pathologischen Befunde bei einem Pferd ein, das an einem Adenokarzinom des Pankreas erkrankt war. Material und Methoden: Ein 17 Jahre alter Warmblutwallach wies seit 2 Wochen Diarrhö, Gewichtsverlust und erhöhte Leberwerte im Serum auf. Er wurde in der Klinik vorgestellt, als zusätzlich Fieber auftrat. Nach klinischer, labordiagnostischer und sonographischer Untersuchung erfolgte eine symptomatische Behandlung. Ergebnisse: Das Pferd entwickelte neben der initialen Diarrhö ein zunehmendes Ödem im Unterbrust- und Bauchbereich, einen Aszites und steigende Leberenzymktivitäten. Aufgrund des progressiven Krankheitsverlaufs musste das Tier nach 3 Tagen euthanasiert werden. Die Sektion ergab ein metastasierendes Pankreaskarzinom. Schlussfolgerung: Pankreaskarzinome sind beim Pferd sehr selten und lassen sich intra vitam schwer diagnostizieren. Bei bisher beschriebenen Fällen wurde die Diagnose immer post mortem gestellt. Klinische Relevanz: Bei Lebererkrankungen mit Aszites sollte auch beim Pferd ein Pankreaskarzinom differenzialdiagnostisch in Betracht gezogen werden.

Prevention of equine herpesvirus myeloencephalopathy - Is heparin a novel option? A case report

Equine herpesvirus myeloencephalopathy (EHM) is a severe manifestation of equine herpesvirus 1 (EHV-1) infection. Prevention and treatment of EHM during EHV-1 outbreaks is critical, but no reliable and tested specific medication is available. Due to the thromboischemic nature of EHM and due to the fact that EHV-1 entry in cells is blocked by heparin, it was hypothesized that this compound may be useful in reduction of EHM incidence and severity. Therefore, during an acute EHV-1 outbreak with the neuropathogenic G₂₂₅₄/D₇₅₂ Pol variant, metaphylactic treatment with heparin to prevent EHM was initiated. Clinical signs were present in 61 horses (fever n = 55; EHM n = 8; abortion n = 6). Heparin (25000 IU subcutaneously twice daily for 3 days) was given to 31 febrile horses from day 10 of the outbreak, while the first 30 horses exhibiting fever remained untreated. Treatment outcome was analyzed retrospectively. Heparin-treated horses showed a lower EHM incidence (1/31; 3.2%) than untreated horses (7/30; 23.3%; p = 0.03). Results indicate that heparin may be useful for prevention of EHM during an EHV-1 outbreak. These promising data highlight the need for randomized and possibly blinded studies for the use of heparin in EHV-1 outbreaks.

Multiple hypersensitivities including recurrent airway obstruction, insect bite hypersensitivity, and urticaria in 2 warmblood horse populations

BACKGROUND

Multiple hypersensitivities (MHS) have been described in humans, cats, and dogs, but not horses.

HYPOTHESES

Horses suffering from recurrent airway obstruction (RAO), insect bite hypersensitivity (IBH), or urticaria (URT) will have an increased risk of also being affected by another one of these hypersensitivities. This predisposition for MHS also will be associated with decreased shedding of strongylid eggs in feces and with a single nucleotide polymorphism (SNP BIEC2-224511), previously shown to be associated with RAO.

ANIMALS

The first population (P1) included 119 randomly sampled horses representative of the Swiss sporthorse population; the replication population (P2) included 210 RAO-affected Warmblood horses and 264 RAO-unaffected controls. All horses were Warmbloods, 14 years or older.

METHODS

Associations between disease phenotypes (RAO, IBH, URT, MHS) fecal egg counts, the SNP BIEC2-224511 as well as management and environmental factors were investigated.

RESULTS

In P1, RAO-affected horses had a 13.1 times higher odds ratio (OR) of also suffering from IBH (P = .004). In P2, the respective OR was 7.4 (P = .002) and IBH-affected horses also showed a 7.1 times increased OR of concomitantly suffering from URT (P < .001). IBH, URT, and MHS phenotypes were significantly associated with the absence of nematode eggs in the feces.

CONCLUSIONS AND CLINICAL IMPORTANCE

This is the first report of MHS in horses. Specifically, an increased risk for IBH should be expected in RAO-affected horses.

Clinical observations and management of a severe equine herpesvirus type 1 outbreak with abortion and encephalomyelitis

Latent equine herpesvirus type 1 (EHV-1) infection is common in horse populations worldwide and estimated to reach a prevalence nearing 90% in some areas. The virus causes acute outbreaks of disease that are characterized by abortion and sporadic cases of myeloencephalopathy (EHM), both severe threats to equine facilities. Different strains vary in their abortigenic and neuropathogenic potential and the simultaneous occurrence of EHM and abortion is rare. In this report, we present clinical observations collected during an EHV-1 outbreak caused by a so-called “neuropathogenic” EHV-1 G₂₂₅₄/D₇₅₂ polymerase (Pol) variant, which has become more prevalent in recent years and is less frequently associated with abortions. In this outbreak with 61 clinically affected horses, 6/7 pregnant mares aborted and 8 horses developed EHM. Three abortions occurred after development of EHM symptoms. Virus detection was performed by nested PCR targeting gB from nasal swabs (11 positive), blood serum (6 positive) and peripheral blood mononuclear cells (9 positive) of a total of 42 horses sampled. All 6 fetuses tested positive for EHV-1 by PCR and 4 by virus isolation. Paired serum neutralization test (SNT) on day 12 and 28 after the index case showed a significant (≥ 4-fold) increase in twelve horses (n = 42; 28.6%). This outbreak with abortions and EHM cases on a single equine facility provided a unique opportunity for the documentation of clinical disease progression as well as diagnostic procedures.

[Select changes in the upper airways of the horse - an overview]

Horses are obligate nasal breathers and depend on patency of their nasal passages. Several dynamic obstructive diseases in the pharyngeal and laryngeal area can be differentiated by high speed treadmill endoscopy and may be responsible for impaired exercise tolerance in the equine athlete. The anatomical specialty of guttural pouches predisposes the horse to species-specific diseases.

Chlamydophila spp. infection in horses with recurrent airway obstruction: similarities to human chronic obstructive disease

Background

Recurrent airway obstruction (RAO) in horses is a naturally occurring dust-induced disease mainly characterized by bronchiolitis which shows histological and pathophysiological similarities to human chronic obstructive pulmonary disease (COPD). In human COPD previous investigations indicated an association with Chlamydophila psittaci infection. The present study was designed (1) to clarify a possible role of this infectious agent in RAO and (2) to investigate the suitability of this equine disorder as a model for human COPD.

Methods

Clinico-pathological parameters of a total of 45 horses (25 horses with clinical signs of RAO and 20 clinically healthy controls) were compared to histological findings in lung tissue samples and infection by Chlamydiaceae using light microscopy, immunohistochemistry, and PCR.

Results

Horses with clinical signs of RAO vs. controls revealed more inflammatory changes in histology (p = 0.01), and a higher detection rate of Chlamydia psittaci antigens in all cells (p < 0.001) and bronchiolar epithelial cells alone (p < 0.001) by immunohistochemistry. The abundance of chlamydial inclusions increased with the severity of disease. PCR was positive in 60% of horses with RAO vs. 45% of the controls (p = 0.316). OmpA sequencing identified Chlamydophila psittaci (n = 9) and Chlamydophila abortus (n = 13) in both groups with no significant differences. Within the group of clinically healthy horses subgroups with no changes (n = 15) and slight inflammation of the small airways (n = 5) were identified. Also in the group of animals with RAO subgroups with slight (n = 16) and severe (n = 9) bronchiolitis could be formed. These four subgroups can be separated in parts by the number of cells positive for Chlamydia psittaci antigens.

Conclusion

Chlamydophila psittaci or abortus were present in the lung of both clinically healthy horses and those with RAO. Immunohistochemistry revealed acute chlamydial infections with inflammation in RAO horses, whereas in clinically healthy animals mostly persistent chlamydial infection and no inflammatory reactions were seen. Stable dust as the known fundamental abiotic factor in RAO is comparable to smoking in human disease. These results show that RAO can be used as a model for human COPD.

Hirninfarkt nach Coil-Embolisation der A. carotis interna zur Behandlung einer Luftsackmykose

Gegenstand und Ziel: Der Fallbericht beschreibt eine ungewöhnliche Komplikation nach Verschluss der A. carotis interna bei einem Pferd mit Luftsackmykose. Material und Methoden: Eine fünfjährige Haflingerstute wurde aufgrund von Epistaxis vorgestellt. Der Patient wurde klinisch, endoskopisch und labordiagnostisch untersucht. Ergebnisse: Die Diagnose lautete Luftsackmykose mit Blutungsanämie. Die Coil- Embolisation der A. carotis interna gelang intraoperativ nur unvollständig. Etwa 14 Stunden nach dem Eingriff kam es zu neurologischen Ausfällen und schließlich zum Tod des Patienten. Bei der Sektion ergab sich ein Hirnödem mit fokalen Nekrosen und Kompression des Stammhirns. Die Veränderungen wurden von Thromben in den Aufzweigungen der A. carotis interna verursacht, die einen ischämischen Hirninfarkt auslösten. Schlussfolgerung: Nach Coil-Embolisation der A. carotis interna können auch beim Pferd durch Thromben bedingte Komplikationen auftreten. Klinische Relevanz: Bei der Coil-Platzierung in Arterien zur Behandlung einer Luftsackmykose sollte der Eingriff erst beendet werden, wenn ein Blutfluss in Richtung Gehirn nicht mehr nachweisbar ist.

DER KLINISCHE FALL: Hämaturie bei einem Hengst

Gegenstand: Ein 13-jähriger Friesenhengst wurde mit reduziertem Allgemeinbefinden, Hämaturie und einer mittelgradigen Anämie vorgestellt. Material und Methoden: Der Patient wurde klinisch, ul- trasonographisch und labordiagnostisch untersucht. Nach der Euthanasie erfolgte eine Sektion inklusive histologischer Untersuchung von Gewebeschnitten. Ergebnisse: Bei der transrektalen Untersuchung konnte eine medizinballgroße, derbe Umfangsvermehrung im Becken des Pferdes ertastet werden. Ultrasonogra- phisch wies die Struktur fokal nierenartiges Gewebe auf, andere Lokalisationen zeigten sich kavernös. Aufgrund der fraglichen Prognose wurden dem Besitzer die Euthanasie und eine Sektion vorgeschlagen. Bei der pathologischen Untersuchung zeigte sich ein 40 x 40 x 30 cm großer Tumor mit Hämatom im Bereich der rechten Niere, die in die Umfangsvermehrung einbezogen war. Durch Ruptur des Bauchfells war der retroperitoneale Raum mit der Bauchhöhle verbunden und es bestand ein Hämaskos. Die linke Niere war unverändert. Bei der histologischen Untersuchung erwies sich die Zubildung als Renalzellkarzinom. Schlussfolgerung: Das Symptom der Hämaturie kann auch beim Pferd durch ernsthafte und lebensbedrohliche Ursachen ausgelöst werden, sodass zur frühzeitigen Diagnosefindung und eventuell möglichen kausalen Therapie unverzüglich weiterführende Untersuchungen veranlasst werden sollten. Klinische Relevanz: Renalzellkarzinome sind bei Pferden selten beschrieben. Zudem wurden sie in der deutschsprachigen Literatur nach Kenntnis der Autoren bei dieser Tierart bislang nicht als Ursache eines Hämaskos genannt.

Second-generation microstimulator

The first-generation injectable microstimulator was glass encased with an external tantalum capacitor electrode. This second-generation device uses a hermetically sealed ceramic case with platinum electrodes. Zener diodes protect the electronics from defibrillation shocks and from electrostatic discharge. The capacitor is sealed inside the case so that it cannot be inadvertently damaged by surgical instruments. This microstimulator, referred to as BION, is the main component of a 255-channel wireless stimulating system. BION devices have been implanted in rats for periods of up to 5 months. Results show benign tissue reactions resulting in identical encapsulation around BION and controls. Stimulation threshold levels did not change significantly over time and ranged between 0.81 to 1.35 mA for all the animals at a 60 micros pulse width. All of the tests performed to date indicate that the BION is safe and effective for long-term human implant. We have elected to develop BION applications by seeking collaboration with the research community through our BION Technology Partnership.

[Percutaneous occlusion of arterial vessels using permanent embolization for the treatment of an air sac hemorrhage in horses. A case report]

This article reports a case of guttural pouch bleeding which was managed successfully by using intravascular embolisation systems to occlude the damaged vessels. Percutaneous catheterisation of the common carotid artery allowed angiographic visualisation of the main head arteries: A. carotis externa, A. carotis interna and A. occipitalis, which showed no abnormalities angiographically. Originating from the A. occipitalis, one artery sent smaller, extensively branching and tortuous vessels to the guttural pouch area. This branching was interpreted as a sign of inflammatory hypervascularization. The artery was occluded by positioning of a detachable balloon distally of the origin of the two small vessels. Insertion of two coils in the A. occipitalis proximally of the origin of this artery completed the embolisation. Occlusion of the distal part was necessary to avoid blood supply to the lesion from the contralateral arterial system via the circle of Willis. The technique used allowed occlusion of a selected head artery without direct surgical intervention in this area. There is no need to remove the implants. After catheterisation, no more episodes of epistaxis occurred. The causing diphtheroid inflammation in the guttural pouch was treated by local infusions of iodine-solutions and resolved completely within 24 days.

[Equine Cushing syndrome (ECS). Case report, review of its diagnosis and therapy and substantial differences from Cushing syndrome in dogs]

Equine and canine Cushing's syndrome, both of which are the result of elevated cortisol levels, show some different pathogenetical and clinical features and require different therapeutical approaches. In older horses the equine Cushing's syndrome (ECS) is not uncommon. Nearly all cases result from excessive hormone production in cells of the pars intermedia of the pituitary. Besides elevated levels of adrenocorticotrope hormone (ACTH), high peripheral levels of pro-opiomelanocortin, beta-endorphines and alpha-melanocyte-stimulating hormone can be measured. In middle-aged and geriatric dogs, Cushing's syndrome is the most frequently diagnosed endocrinologic abnormality. 80-85% of cases are pituitary-dependent and 15-20% are caused by cortisol producing tumors of the adrenals. 90% of pituitary lesions can be identified as adenomas, which are localised in most cases in the pars distalis of the gland, but may occur rarely in the pars intermedia, too. Clinical symptoms in both species are characterised by wasting despite good appetite or polyphagia, reduction of muscle mass with altered fat deposition and lethargy. Whereas polydipsia/polyuria is a very common feature in dogs with Cushing's syndrome, in horses it is almost invariably a sign of concurrent secondary diabetes mellitus. A typical symptom in ECS is a continuously growing haircoat (hirsutism), whereas in canine Cushing's syndrome generalised alopecia may bring the owner to consult a veterinarian. The symptoms and diagnostic procedures in a 33-year-old mare are described. Useful diagnostic tests are reviewed with special attention to species differences in reacting to them. The therapeutic approach with dopamine-agonists such as bromocriptine and pergolide as well as cyproheptadine to ECS is reviewed.

[Demonstration of activity of two potentiated sulfonamides in feces of horses after oral or intravenous administration]

Both, the oral and intravenous application of two trimethoprim-potentiated sulfonamides induced measurable antibacterial activities in the feces of horses. With regard to the risk of antibiotic-induced alterations of the gastrointestinal flora, the route of application of potentiated sulfonamides seems to be of minor importance. The antibiotics used were Sulfadimethoxine/Trimethoprim (Trafigal 30% ad us. vet.) for oral and Sulfadoxine/Trimethoprim (Borgal 24% ad us. vet., both Hoechst AG, Frankfurt) for intravenous application. As recommended, both drugs were given in a dose of 20 mg per kg bodyweight. The detection method is based on a procedure layed down in German laws for sulfonamide residues in meat-samples and has undergone some modifications for the examination of feces.

Equine adenocarcinomas of the large intestine with osseous metaplasia

Large intestinal adenocarcinoma with osseous metaplasia was diagnosed in two horses, a 15-year-old standard bred gelding and a 9-year-old Haflinger mare. Clinically, both animals had displayed weight loss and anaemia. A presumptive diagnosis of abdominal neoplasia was made and the horses were humanely killed. At necropsy, the gelding and the mare were found to have ulcerated tumours growing into the lumen of the caecum and colon, respectively. In the mare, the mass extended through the mesocolon and was evident in the left dorsal and ventral colon. Histopathologically, the tumours consisted of well-differentiated cords of single-layered columnar to cuboidal epithelial cells. Mitotic figures were very uncommon. In both lesions, well-formed bony spicules and osteoid were present in the fibrovascular stroma. The tumours were well-demarcated from surrounding mucosal tissue but had invaded the intestinal wall. Metastases were not observed.

[Susceptibility of bacterial isolates from the equine respiratory tract to trimethoprim, sulfadoxine, sulfadimethoxine and combinations of these compounds]

Using a broth microdilution technique, the in vitro susceptibility of bacterial isolates from the equine respiratory tract to trimethoprim, sulfadoxine, sulfadimethoxine, and combinations of these compounds was determined. The bacterial strains (n = 88) isolated recently from horses with respiratory symptoms belonged to the following species: Streptococcus equi subsp. zooepidemicus (n = 34), Streptococcus equi subsp. equi (n = 22), Staphylococcus aureus (n = 9), Klebsiella pneumoniae (n = 7), Rhodococcus equi (n = 4), Pseudomonas spp. (n = 3) and Escherichia coli (n = 3). In addition, two isolates of Enterobacter spp. and one isolate of Streptococcus equisimilis, Staphylococcus intermedius, Proteus mirabilis and Serratia marcescens were examined. For determination of susceptibility of an organism the following minimal inhibitory concentrations (MIC) were fixed as limiting values: Trimethoprim < or = 0.5 microgram/ml, sulfadoxine < or = 32 micrograms/ml, sulfadimethoxine < or = 32 micrograms/ml, trimethoprim/sulfadoxine < or = 0.5/32 micrograms/ml, trimethoprim/sulfadimethoxine < or = 0.5/32 micrograms/ml. As expected, Rhodococcus-equi-isolates were resistant to the antimicrobials tested. However, most of the clinically more common isolates showed a high degree of susceptibility to the combinations. The fractional inhibitory concentration (FIC) indices indicated synergism of the combination-partners in a wide range. According to these in vitro results, application of trimethoprim/sulfonamide combinations for the initial therapy of equine respiratory tract infections can be recommended.

[Demonstration of two trimethoprim/sulfonamide combinations in bronchoalveolar lavage fluid of horses and determination of blood levels]

Five healthy horses were given a sulfadoxine/trimethoprim combination (Borgal, Hoechst AG) i.v. on day 1. The next ten days the horses got once a day a sulfadimethoxine/trimethoprim combination orally (Trafigal, Hoechst AG). The doses were given as recommended. One horse received no medicaments for control. On each horse six bronchoalveolar lavages were performed. Blood samples were taken to calculate blood levels and elimination half lives. To determine the amount of substances in lavage fluid and plasma the high performance liquid chromatography (HPLC) was used. Regularly low quantities of sulfonamides and trimethoprim were detected in lavage-samples. The mean plasma concentration (n = 4) of sulfadoxine and trimethoprim 30 min after i.v. administration was 71.6 and 1.13 micrograms/g respectively. 24 h after injection the sulfadoxine blood level was 3.0 micrograms/g, while trimethoprim was no longer detectable. The average elimination half lives of sulfadoxine and trimethoprim were 7.94 h and 1.35 h respectively. 8 h after oral application (n = 5) the highest mean sulfadimethoxine blood levels of 53.8 micrograms/g were measured. The elimination half life of sulfadimethoxine was 9.77 h. Two hours after feeding the drug the first blood samples were taken. They already contained the highest mean trimethoprim concentration of 0.32 microgram/g plasma.

Cluster formation in a symmetrical network: a dynamical system for the description of the suppression among non-immune T lymphocytes and its application to the effects of immunization

A mathematical model has been developed for the description of the suppressive regulation between polyclonally activated normal and immune T cells. The model assumes reversible cell-cell interactions to interpret results from limiting dilution experiments performed to determine the frequencies of precursor cells for antigen-specific T effector lymphocytes and to analyse mechanisms regulating the maturation of precursor into effector T cells. In particular, the model deals with the changes induced in the T lymphocytes population following immunization with antigens. In these limiting dilution experiments, T cells are placed in cultures at varying cell numbers with all other essential culture constituents kept in excess. After polyclonal activation of the T cells in culture they are supplied with growth and maturation factors so that they form daughter clones of functionally active T effector cells. The typical result observed was that effector T cells develop in cultures at low cell input but that this development is totally suppressed at high cell numbers. This result suggested that, at high cell numbers, the effector T cells are exposed to a sufficient number of other T cells of appropriate specificity to permit suppressive interactions. Whereas this is the case for non-immune T cells, T cells after immunization develop into effector cells both at high as well as at low cell concentrations, though with efficiencies less than proportional to their number of precursors. Our mathematical model is made up of a set of first order autonomous ordinary differential equations in many variables permitting the calculations of numbers of free cells and of cells engaged in cellular clusters of varying sizes. Free cells can develop into effector cells whereas cells engaged in clusters cannot. We calculate the consequences of several reasonable hypotheses concerning the effects of immunization. We consider the possibility that immunization modifies the growth behavior of the antigen-specific cells to permit an increased or accelerated clonal expansion in culture. Alternatively, we consider the possibility that immunization changes the interaction strength between cells specific for the immunizing antigen and other cells. Thirdly, we have connected both behaviors by calculating the case of an inverse relationship between growth rates and intensities of interaction between cells. Our model has been inspired by the symmetrical network model and can be interpreted in this framework. It proposes that immune regulation is a consequence of idiotype-anti-idiotype interactions.(ABSTRACT TRUNCATED AT 400 WORDS)

Quantitative studies on T cell diversity. IV. Mathematical analysis of multiple limiting populations of effector and suppressor T cells

Limiting dilution (LD) analyses of polyclonally activated T cells yielded results suggesting the existence of multiple paired populations of effector and suppressor precursors for a number of different T cell functions and specificities analyzed. These populations occur at graded frequencies and suppression occurs within a pair but not between pairs. In this paper, we establish the mathematical basis for the interpretation of these multi-component limiting dilution results. First, we derive equations for a number of mathematical models and identify one model that both makes biological sense and can be used to reproduce experimental data. Second, within this model, we identify parameters such as the frequency of suppressive cells and the number of suppressive cells required for suppression. The results suggest that within each paired population, suppressor precursors are 20 times more frequent that effector precursors. Furthermore, a similar but variable excess of suppressor cells is required for suppression to become effective. Together with the high frequency (1/50-1/500) of most effector T cell precursors previously reported, the results suggest that up to 40% of the T cells can become involved in suppression of an antigen-specific effector T cell population. These studies may provide exact estimates for predictions to be tested in experiments on immune regulation.

Quantitative studies on T cell diversity. III. Limiting dilution analysis of precursor cells for T helper cells reactive to xenogeneic erythrocytes

Splenic T cells exposed to concanavalin A (Con A), and subsequently to factors produced by rat spleen cells in response to Con A (Con A sup), acquire the ability to function as helper T (TH) cells in response to xenogeneic erythrocytes (RBC). Help is measured as the reconstitution of the plaque-forming cell response of a spleen cell population depleted of T cells by treatment with anti-Thy-1 serum and complement. We propose that precursor TH cells differentiate during the in vitro treatment into mature TH cells. As differentiation occurs under limiting dilution conditions, an estimation of the precursor frequency should in principle be possible. However, a single-hit Poisson distribution does not fit our data. Instead, we observe, dependent on the T cell concentration, three separate "peaks" of response. In many experiments, using sheep, horse, and chicken RBC as antigens, we reproducibly find these "peaks" at 40-190, 600-3,000, and 20,000-100,000 T cells, placed into limiting dilution cultures, respectively. By various experiments we can show that the helper activity is not due to passively transferred rat factors, but to the titrated cells themselves. The active cell is a T cell that appears to function in an antigen-specific way and to require direct cell contact to do so. It thus resembles the classical helper T cell. As we find precursor TH cells already at very low concentrations of T cells, we titrated the range between 0 and 100 T cells/well carefully. The bent shape of the titration curves does not always allow a statistically satisfying regression analysis, and we therefore cannot estimate precise precursor frequencies from every experiment. However, a common sense argument can be made that these frequencies must be on the order of 1/10-1/100 T cells. We propose that the limiting dilution curves obtained in this system most likely reflect fundamentally important cellular interactions that regulate immunological effector functions. We favor a concept of independently interacting sets of helper and suppressor T cells of various frequencies, but other models are possible.

Reducing postischemic damage by temporary modification of reperfusate calcium, potassium, pH, and osmolarity

This study was designed to determine if ischemic damage could be reduced by modifying blood composition upon reperfusion. After control data had been obtained in seven dogs on prolonged cardiopulmonary bypass, 71 dogs underwent 1 hour of ischemic arrest with topical hypothermia (left ventricular temperature 16 degrees C). We measured left ventricular performance (isovolumetric function curves), compliance (intraventricular balloon), blood flow (microspheres), metabolism (oxygen consumption), and water content (wet/dry weights) before and 30 minutes after ischemia. The initial reperfusate was 500 cc of oxygenated blood given over a period of 5 minutes. Without temporary reperfusate modification, postischemic left ventricular performance was depressed 40% +/- 3%, compliance fell 50% +/- 12%, water content rose 2.5% +/- 0.1%, and left ventricular blood flow and oxygen uptake increased only minimally when cardiac work was increased (function curve). These deleterious changes were reduced significantly, but not prevented, by the following isolated reperfusate modifications: (1) lowering amount of ionic calcium available for cell entry, (2) raising pH to 7.8 to counteract acidosis, (3) raising potassium level to maintain arrest and reduce metabolic demands, and (4) increasing osmolarity (mannitol, 360 mOsm) to counteract edema. In contrast, by combining these modifications to achieve a hypocalcemic, hyperkalemic, alkalotic, and hyperosmolar blood perfusate, it was possible to attain 104% +/- 1% recovery of myocardial performance, 80% +/- 1% restoration of compliance, 60% less postischemic edema, and near-normal augmentation of left ventricular flow and oxygen uptake to meet increasing needs.

Superiority of blood cardioplegia over asanguinous cardioplegia--an experimental and clinical study

This study compares experimental and clinical results using both an asanguinous and sanguinous vehicle for delivering the cardioplegic solution. Animals receiving blood cardioplegia had better left ventricular function after unclamping, significantly less post-ischemic myocardial edema, and a better ability to augment flow and oxygen consumption. Patients receiving blood cardioplegia had also better myocardial performance with high cardiac outputs and lower left atrial pressure, and showed less evidence of myocardial damage. We conclude that oxygenation of the cardioplegic solution provides superior myocardial protection to that seen when the same solution is used in an asanguinous vehicle.

Regional myocardial blood flow after hypothermic arrest and cardioplegia

Malperfusion due to increased coronary vascular resistance is presumably one of the factors responsible for incomplete functional recovery of the heart after aortic cross-clamping. Myocaridal blood flow (MBF, radioactive microspheres) was measured before and after 60 min of hypothermic ischemia in 16 dogs on cardiopulmonary bypass. After ischemia the hearts were reperfused for 30 min. MBF was measured in the empty beating heart and in the isovolumetrically contracting ventricle loaded with enddiastolic volumes (EDV) of 10, 20 and 30 ml (intraventricular latex balloon).

Advantages of intermittent blood cardioplegia over intermittent ischemia during prolonged hypothermic aortic clamping

Ten dogs underwent 2 hours of hypothermic (22 degrees C) aortic clamping. Arrest was produced by ischemia in five dogs, with 150 ml of 22 degrees C unmodified blood reperfused every 20 minutes. Five others underwent cardioplegic arrest (500 cc pH 7.8 blood containing 30 mEq/L KCl, 0.6 mEq/L Ca++) with 150 ml of blood cardioplegia solution replenished each 20 minutes. Seven additional dogs underwent 4 hours of continuous coronary perfusion without ischemia. Continuous coronary perfusion did not change myocardial ATP or water content, but reduced left ventricular contractility (maximum positive dP/dt, peak systolic pressure) 16% (P < 0.05) and decreased left ventricular compliance moderately (50%). Hypothermic ischemic arrest reduced myocardial ATP 39% (P < 0.05), raised myocardial water 3.2% (P < 0.05), reduced compliance 83% (P < 0.05), and depressed left ventricular performance 64% (P < 0.05), despite intermittent reinfusion of unmodified blood each 20 minutes. In contrast, blood cardioplegia reduced postischemic left ventricular compliance only slightly 17%, P < 0.05) and resulted in normal postischemic ATP, water, and contractility.