What is Known About Critical Congenital Heart Disease Diagnosis and Management Experiences from the Perspectives of Family and Healthcare Providers? A Systematic Integrative Literature Review.

The experience of diagnosis, decision-making and management in critical congenital heart disease is layered with complexity for both families and clinicians. We synthesise the current evidence regarding the family and healthcare provider experience of critical congenital heart disease diagnosis and management. A systematic integrative literature review was conducted by keyword search of online databases, MEDLINE (Ovid), PsycINFO, Cochrane, cumulative index to nursing and allied health literature (CINAHL Plus) and two journals, the Journal of Indigenous Research and Midwifery Journal from 1990. Inclusion and exclusion criteria were applied to search results with citation mining of final included papers to ensure completeness. Two researchers assessed study quality combining three tools. A third researcher reviewed papers where no consensus was reached. Data was coded and analysed in four phases resulting in final refined themes to summarise the findings. Of 1817 unique papers, 22 met the inclusion criteria. The overall quality of the included studies was generally good, apart from three of fair quality. There is little information on the experience of the healthcare provider. Thematic analysis identified three themes relating to the family experience: (1) The diagnosis and treatment of a critical congenital heart disease child significantly impacts parental health and wellbeing. (2) The way that healthcare and information is provided influences parental response and adaptation, and (3) parental responses and adaptation can be influenced by how and when support occurs. The experience of diagnosis and management of a critical congenital heart disease child is stressful and life-changing for families. Further research is needed into the experience of minority and socially deprived families, and of the healthcare provider, to inform potential interventions at the healthcare provider and institutional levels to improve family experience and support.

The application of a new laminitis scoring method to model the rate and pattern of improvement from equine endocrinopathic laminitis in a clinical setting.

BACKGROUND: Endocrinopathic, or hyperinsulinaemia-associated laminitis (HAL) is a common and debilitating equine foot disease, and although no pharmacological treatments are registered, several are under development. To evaluate the effect of such treatments, an accurate and consistent method is needed to track the clinical signs of laminitis over time, and the natural history of the disease, in terms of a 'normal' pattern of improvement, needs to be understood. This study examined the improvement pattern in clinical cases of naturally-occurring HAL subjected to a range of best-practice interventions, using two different scoring methods. Eighty horses and ponies with suspected HAL were enrolled in a study conducted at 16 veterinary practices across Germany. The severity of laminitis was assessed by independent veterinarians using both the traditional Obel method and a modified Obel method developed by Meier and colleagues. Assessments were made on the day of diagnosis (d 0), then on days 4, 9, 14, 25 and 42 during the intervention period. Pain medications were withheld for 24 h prior to clinical examination in all cases. RESULTS: Time to marked improvement from laminitis varied between individuals, but was difficult to monitor accurately using the Obel method, with the median grade being 2/4 on days 0 and 4, then 0/4 from d 9 onwards. More subtle changes could be identified using the Meier method, however, and the median scores were seen to follow the form of an exponential decay model in most horses, improving from 8/12 on d 0, to 0/12 on d 25. Within this composite scoring method, considerable variation was observed in the rate of improvement of individual clinical signs, with the average time taken for each sign to reach a median score of 0 ranging from 4 days (foot lift and weight shifting) to 25 days (gait when turned in a circle) across all 80 horses. CONCLUSIONS: The Meier method provides a reliable and consistent method for monitoring the clinical status of horses with HAL, and despite the variability, the pattern of improvement described here should provide a useful benchmark against which individual cases and new treatments can be assessed.

Maternal right ventricular function, uteroplacental circulation in first trimester and pregnancy outcome in women with congenital heart disease.

OBJECTIVE: Pregnant women with congenital heart disease (CHD) have an increased risk of abnormal uteroplacental flow, measured from the second trimester onwards, which is associated with pregnancy complications affecting the mother and the fetus. Maternal right ventricular (RV) dysfunction has been suggested as a predisposing factor for impaired uteroplacental flow in these women. The aim of this study was to investigate the association of first-trimester uteroplacental flow measurements with prepregnancy maternal cardiac function and pregnancy complications in women with CHD, with particular focus on the potential role of RV (dys)function. METHODS: This study included 138 pregnant women with CHD from the prospective ZAHARA III study (Zwangerschap bij Aangeboren HARtAfwijkingen; Pregnancy and CHD). Prepregnancy clinical and echocardiographic data were collected. Clinical evaluation, echocardiography (focused on RV function, as assessed by tricuspid annular plane systolic excursion (TAPSE)) and uterine artery (UtA) pulsatility index (PI) measurements were performed at 12, 20 and 32 weeks of gestation. Univariable and multivariable regression analyses were performed to assess the association between prepregnancy variables and UtA-PI during pregnancy. The association between UtA-PI at 12 weeks and cardiovascular, obstetric and neonatal complications was also assessed. RESULTS: On multivariable regression analysis, prepregnancy TAPSE was associated negatively with UtA-PI at 12 weeks of gestation (ß = -0.026; P = 0.036). Women with lower prepregnancy TAPSE (≤ 20 mm vs > 20 mm) had higher UtA-PI at 12 weeks (1.5 ± 0.5 vs 1.2 ± 0.6; P = 0.047). Increased UtA-PI at 12 weeks was associated with obstetric complications (P = 0.003), particularly hypertensive disorders (pregnancy-induced hypertension and pre-eclampsia, P = 0.019 and P = 0.026, respectively). CONCLUSIONS: In women with CHD, RV dysfunction before pregnancy seems to impact placentation, resulting in increased resistance in UtA flow, which is detectable as early as in the first trimester. This, in turn, is associated with pregnancy complications. Early monitoring of uteroplacental flow might be of value in women with CHD with pre-existing subclinical RV dysfunction to identify pregnancies that would benefit from close obstetric surveillance. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

The efficacy and safety of velagliflozin over 16 weeks as a treatment for insulin dysregulation in ponies.

BACKGROUND: A previous six-week (wk) study demonstrated the potential of the sodium-glucose linked transport inhibitor velagliflozin as a novel treatment for equine insulin dysregulation. The present study examined the safety and efficacy of velagliflozin over 16 wk. of treatment, and over 4 wk. of withdrawal. Twenty-four insulin dysregulated ponies were selected, based on their hyper-responsiveness to a diet challenge meal containing 3.8 g non-structural carbohydrates (NSC)/kg bodyweight (BW). Ponies with serum insulin > 90 µIU/mL either 2 or 4 h after feeding were enrolled, and randomly allocated to receive either velagliflozin (0.3 mg/kg BW orally once daily, n = 12), or a placebo (n = 10-12) for 16 wk. The subjects were fed 7.5 g NSC/kg BW/day to maintain a fat body condition. Safety was assessed through daily monitoring, veterinary examination, and the measurement of fasting blood glucose, biochemistry and haematology. Efficacy at reducing post-prandial hyperinsulinemia was assessed using a diet challenge every 8 wk. during treatment and 4 wk. after withdrawal. RESULTS: Velagliflozin was well accepted by all subjects and caused no adverse effects or hypoglycaemia. Post-prandial serum insulin (insulin Cmax) did not change significantly in the control animals over the entire study period (P = 0.101). In contrast, insulin Cmax (mean ± SE) concentrations fell over time in the velagliflozin-treated group from 205 ± 25 µIU/mL in wk. 0, to 119 ± 19 µIU/mL (P = 0.015) and 117 ± 15 µIU/ml (P = 0.029) after 8 and 16 wk. of treatment, respectively. Although the insulin Cmax in this group was not significantly lower than in controls at wk-8 (P = 0.061), it was lower at wk-16 (P = 0.003), and all 12 treated ponies were below the previously-determined risk threshold for laminitis at this time. After 4 wk. withdrawal, the insulin Cmax returned to 199 ± 36 µIU/mL in the treated group, with no rebound effect. CONCLUSIONS: Velagliflozin appears to be a promising and safe treatment for equine insulin dysregulation, bringing post-prandial insulin concentrations below the laminitis risk threshold, albeit without normalising them.

Maternal and neonatal outcomes in women with severe early onset pre-eclampsia before 26 weeks of gestation, a case series.

OBJECTIVE: To describe the maternal and neonatal outcomes and prolongation of pregnancies with severe early onset pre-eclampsia before 26 weeks of gestation. DESIGN: Nationwide case series. SETTING: All Dutch tertiary perinatal care centres. POPULATION: All women diagnosed with severe pre-eclampsia who delivered between 22 and 26 weeks of gestation in a tertiary perinatal care centre in the Netherlands, between 2008 and 2014. METHODS: Women were identified through computerised hospital databases. Data were collected from medical records. MAIN OUTCOME MEASURES: Maternal complications [HELLP (haemolysis, elevated liver enzyme levels, and low platelet levels) syndrome, eclampsia, pulmonary oedema, cerebrovascular incidents, hepatic capsular rupture, placenta abruption, renal failure, and maternal death], neonatal survival and complications (intraventricular haemorrhage, retinopathy of prematurity, necrotising enterocolitis, bronchopulmonary dysplasia, and sepsis), and outcome of subsequent pregnancies (recurrent pre-eclampsia, premature delivery, and neonatal survival). RESULTS: We studied 133 women, delivering 140 children. Maternal complications occurred frequently (54%). Deterioration of HELLP syndrome during expectant care occurred in 48%, after 4 days. Median prolongation was 5 days (range: 0-25 days). Neonatal survival was poor (19%), and was worse (6.6%) if the mother was admitted before 24 weeks of gestation. Complications occurred frequently among survivors (84%). After active support, neonatal survival was comparable with the survival of spontaneous premature neonates (54%). Pre-eclampsia recurred in 31%, at a mean gestational age of 32 weeks and 6 days. CONCLUSIONS: Considering the limits of prolongation, women need to be counselled carefully, weighing the high risk for maternal complications versus limited neonatal survival and/or extreme prematurity and its sequelae. The positive prospects regarding maternal and neonatal outcome in future pregnancies can supplement counselling. TWEETABLE ABSTRACT: Severe early onset pre-eclampsia comes with high maternal complication rates and poor neonatal survival.

Uteroplacental Doppler flow and pregnancy outcome in women with tetralogy of Fallot.

OBJECTIVE: Pregnancy in women with surgically corrected tetralogy of Fallot (ToF) is associated with cardiac, obstetric and neonatal complications. We compared uteroplacental Doppler flow (UDF) measurements and pregnancy outcome in women with ToF and in healthy women and aimed to assess whether a relationship exists between cardiac function and UDF in women with ToF. METHODS: We evaluated prospectively pregnant women with ToF and healthy pregnant women from the ZAHARA studies. Clinical evaluation, standardized echocardiography and UDF measurements were performed at 20 and 32 weeks' gestation. RESULTS: We included 62 women with ToF and 69 healthy controls. Cardiac complications, mostly arrhythmia, occurred in 8.1% of women with ToF. There was a higher incidence of small-for-gestational age (21.0% vs 4.4%, P = 0.004) and low birth weight (16.1% vs 2.9%, P = 0.009) in the group of women with ToF than in healthy controls. In women with ToF, early diastolic notching of uterine artery waveform at 20 and 32 weeks occurred more frequently (9.8% vs 1.5%, P = 0.034 and 7.0% vs 0%, P = 0.025, respectively) and the umbilical artery pulsatility index at 32 weeks was higher (1.02 ± 0.20 vs 0.94 ± 0.17, P = 0.015) than in healthy controls. Right ventricular function parameters prepregnancy and at 20 weeks' gestation were significantly associated with abnormal UDF. UDF parameters were associated with adverse neonatal outcome. CONCLUSION: The majority of women with surgically corrected ToF tolerate pregnancy well. However, UDF indices are more frequently abnormal in these women, suggesting impaired placentation. The association of impaired right ventricular function parameters with abnormal UDF suggests that cardiac dysfunction contributes to defective placentation or placental perfusion mismatch and may explain the increased incidence of obstetric and neonatal complications. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Equine hyperinsulinemia: investigation of the enteroinsular axis during insulin dysregulation.

Compared with some other species, insulin dysregulation in equids is poorly understood. However, hyperinsulinemia causes laminitis, a significant and often lethal disease affecting the pedal bone/hoof wall attachment site. Until recently, hyperinsulinemia has been considered a counterregulatory response to insulin resistance (IR), but there is growing evidence to support a gastrointestinal etiology. Incretin hormones released from the proximal intestine, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide, augment insulin secretion in several species but require investigation in horses. This study investigated peripheral and gut-derived factors impacting insulin secretion by comparing the response to intravenous (iv) and oral d-glucose. Oral and iv tests were performed in 22 ponies previously shown to be insulin dysregulated, of which only 15 were classified as IR (iv test). In a more detailed study, nine different ponies received four treatments: d-glucose orally, d-glucose iv, oats, and commercial grain mix. Insulin, glucose, and incretin concentrations were measured before and after each treatment. All nine ponies showed similar iv responses, but five were markedly hyperresponsive to oral d-glucose and four were not. Insulin responsiveness to oral d-glucose was strongly associated with blood glucose concentrations and oral glucose bioavailability, presumably driven by glucose absorption/distribution, as there was no difference in glucose clearance rates. Insulin was also positively associated with the active amide of GLP-1 following d-glucose and grain. This study has confirmed a functional enteroinsular axis in ponies that likely contributes to insulin dysregulation that may predispose them to laminitis. Moreover, iv tests for IR are not reliable predictors of the oral response to dietary nonstructural carbohydrate.

Palliative care needs at different phases in the illness trajectory: a survey study in patients with cancer.

Despite the growing consensus on the benefits of initiating palliative care early in the disease trajectory, it remains unclear at what point palliative care needs emerge. This study investigates quality of life and unmet palliative care needs at three phases in the cancer trajectory, curative, life-prolonging and most advanced (prognosis <6 months/no further disease-modifying treatment). We collected self-reported data from 620 patients with cancer in the University Hospital of Ghent, Belgium. They completed a questionnaire on quality of life (using the EORTC QLQ-C30) and unmet care needs within the domains of palliative care. We used European reference values of the EORTC QLQ-C30 to compare the mean scores with a norm group. The groups further on in the cancer trajectory reported statistically and clinically poorer functioning compared with earlier phases, also when controlled for the effects of sex, age or type of cancer. Higher symptom burdens for fatigue, pain, dyspnoea and appetite loss were found in groups further into the trajectory, p < .001. Patients in the curative phase experienced physical symptoms and had clinically worse functioning than a European reference group. This paper demonstrates the ongoing need for oncologists to address the broader palliative care needs of patients from diagnosis onwards.

Prolonged hyperinsulinemia increases the production of inflammatory cytokines in equine digital lamellae but not in striated muscle.

Hyperinsulinemia is the key feature of equine metabolic syndrome (EMS) which leads to debilitating sequelae. Hyperinsulinemia-associated laminitis (HAL) is one of the major sequelae of EMS, although the pathophysiological mechanisms are not well elucidated. Using an equine model, we hypothesized that expression of inflammatory markers would be increased in digital lamellae and striated muscle following prolonged hyperinsulinemia. Healthy Standardbred horses (5.4 ± 1.9 years) were alternately assigned to a prolonged euglycemic-hyperinsulinemic clamp (pEHC) or control group (n = 4 per group). Following a 48 h pEHC or a 48 h infusion of a balanced electrolyte solution (controls), biopsies were collected from digital lamellar tissue, skeletal muscle and cardiac muscle were obtained. All hyperinsulinemic horses developed laminitis regardless of previous health status at enrollment. Protein expression was quantified via Western blotting. A significant (P < 0.05) upregulation of the protein expression of heat shock protein 90 (HSP90), alpha 2 macroglobulin (A2M) and fibrinogen (α, ß isoforms), as well as inflammatory cytokines including interleukin-1ß were detected in digital lamellae following prolonged hyperinsulinemia. In contrast, protein expression of cytokines and acute phase proteins in heart and skeletal muscle was unchanged following hyperinsulinemia. Upregulation of inflammatory cytokines and acute phase proteins in digital lamellae during prolonged hyperinsulinemia may reveal potential biomarkers and novel therapeutic targets for equine endocrinopathic laminitis. Further, the lack of increase of inflammatory proteins and acute phase proteins in striated muscle following prolonged hyperinsulinemia may highlight potential anti-inflammatory and cardioprotective mechanisms in these insulin-sensitive tissues.

Evaluation of antenatal umbilical coiling index at 16-21 weeks of gestation as a predictor of trisomy 21 and other chromosomal defects.

OBJECTIVES: To determine whether there is an association between sonographically assessed hyper- or hypocoiling of the umbilical cord and the presence of trisomy 21, to provide reference values for the antenatal umbilical coiling index (aUCI) at a gestational age of 16-21 weeks and to determine whether these measurements are reliable and reproducible. METHODS: This was a prospective study of 737 pregnancies in which the aUCI was measured between 16 and 21 weeks of gestation by ultrasound at the time of amniocentesis. The aUCI was calculated as the reciprocal value of the mean length of one complete coil in centimeters. We created reference curves and studied the relationship with trisomy 21 and other chromosomal defects. In 30 pregnancies we studied the intra- and interobserver variation in measurements using Bland-Altman plots with associated 95% limits of agreement and intraclass correlation coefficients. RESULTS: aUCI was found to be non-linearly related to gestational age at 16-21 weeks and reference curves were created for the mean aUCI and the 2.3(rd) , 10(th) , 90(th) and 97.7(th) percentiles. There was no significant difference in aUCI values between the reference group (n = 714) and cases with trisomy 21 (n = 16) or other aneuploidies (n = 7) (one-way ANOVA, P = 0.716). There was good intra- and interobserver agreement in aUCI measurements. CONCLUSIONS: The aUCI can be measured reliably and varies according to gestational age at 16-21 weeks. The aUCI was not significantly associated with trisomy 21 or other chromosomal defects.

Diagnosis of equine endocrinopathies: The value of measuring blood glucose during an oral glucose test.

Blood glucose concentration is often measured during an oral glucose test (OGT), but is not thought to aid in diagnosing insulin dysregulation (ID) or pituitary pars intermedia dysfunction (PPID). The aim of this retrospective study was to investigate whether the change in blood glucose concentration during an OGT aligned with indicators of equine metabolic syndrome or PPID, including serum insulin and plasma ACTH concentrations, clinical observations, age, sex, breed type and the test dose. The cohort included 149 horses, miniature horses, and ponies that had undergone an in-feed OGT and clinical examination between 2015 and 2021. The animals were diagnosed as either metabolically healthy, insulin-dysregulated, having PPID or both endocrinopathies. The mean ± standard error increase in blood glucose during the OGT was 3.41 ± 0.21 mM, and this change showed a weak positive correlation with the increase in serum insulin concentration (r = 0.36; P 0.001), body condition score (BCS; r = 0.26; P = 0.002) and cresty neck score (CNS; r = 0.38; P 0.001). The median [interquartile range] increase in blood glucose for miniature horses (5.25 [2.98-6.5] mM), was more than twice that seen in full-sized horses (2.4 [1.33-3.45] mM; P = 0.03). In metabolically healthy animals the increase in blood glucose during an OGT (+2.2 [1-3.5] mM) was smaller (P 0.001) than in animals with ID (+3.8 [2.73-5.33] mM), or both endocrine diseases (+6.1 [3.6-6.85] mM). There was an effect of the dose of dextrose on the blood glucose response, with higher doses yielding larger responses (P 0.001). The variability in these data support that basal and post-prandial blood glucose responses to an OGT are not appropriate as stand-alone diagnostic markers of ID or PPID. However, the association between blood glucose and CNS supports the use of CNS when evaluating animals for ID.

Identification of monoclonal antibodies suitable for blocking IGF-1 receptors in the horse.

Prolonged hyperinsulinemia is thought to be the cause of equine endocrinopathic laminitis, a common and crippling disease of the foot, for which there are no pharmacologic treatments other than pain relief. It has been suggested that insulin causes its effects on the lamellae by activating IGF-1 receptors (IGF-1R), as insulin receptors (InsR) are scarce in this tissue, whereas IGF-1R are abundant and become downregulated after prolonged insulin infusion. As a first step toward confirming this mechanism and beginning to develop a therapeutic anti-IGF-1R monoclonal antibody (mAb) for horses, it was necessary to identify available human IGF-1R mAbs that would recognize equine receptors. Four IGF-1R mAbs were tested using soluble equine IGF-1R, with ELISA and flow cytometry. Frozen equine lamellar and liver tissue was also used in radioligand binding assays. The results demonstrated that only one of the mAbs tested (mAb1) was able to compete effectively with IGF-1 for binding to its receptors in equine lamellar tissue, with an IC50 of 5 to 159 ng/mL. None of the 4 mAbs were able to bind to equine hepatic InsR. This study has generated valuable structure-activity information and has identified a prototype anti-IGF-1R mAb suitable for further development.

Effects of insulin on IGF-1 receptors in equine lamellar tissue in vitro.

Although it is understood that equine endocrinopathic laminitis can be triggered by high concentrations of insulin, it is unclear whether this represents a direct action on lamellar tissue via insulin receptors (InsR), an interaction with IGF-1 receptors (IGF-1R), or some other, indirect action. This uncertainty is because of the reported scarcity of InsR in lamellar tissue and the low affinity of insulin for equine IGF-1R. In the present study, the effects of insulin and IGF-1 (as a positive control) were examined using lamellar explants isolated from the hooves of healthy horses and incubated in cell culture medium for between 2 min and 48 h. In this system, a low physiological concentration of IGF-1 (10 nM; 1.31 ng/mL) caused a marked increase in the appearance of phosphorylated IGF-1R after 5 min (P < 0.05), and this effect was blocked by a human anti-IGF-1R monoclonal antibody (mAb). However, a high concentration of insulin (10 nM; 1,430 µIU/mL) appeared to cause dephosphorylation of the IGF-1R after 5 min (P < 0.01), 15 min, and 30 min (P < 0.001). Using 3H-thymidine as a marker, it was also demonstrated that insulin and IGF-1-stimulated cell proliferation in lamellar explants over the same concentration range as each other (1-100 nM), implying that each peptide acts via its own receptor (P < 0.001). Conversely, the effect of both peptides could be blocked using a selective anti-IGF-1R mAb (P < 0.001), implying that insulin acts via IGF1-R (either directly or indirectly). Notwithstanding this conundrum, the results demonstrate that insulin acts directly on lamellar tissue and suggest that a therapeutic anti-IGF-1R mAb could be useful in treating or preventing endocrinopathic laminitis.

Equine laminitis: induced by 48 h hyperinsulinaemia in Standardbred horses.

REASONS FOR PERFORMING STUDY: Hyperinsulinaemia is known to induce laminitis experimentally in healthy ponies with no history of the condition. Horses are more insulin sensitive than ponies and whether prolonged hyperinsulinaemia and euglycaemia would have a similar laminitogenic effect requires study. OBJECTIVES: To determine if laminitis results when the prolonged euglycaemic hyperinsulinaemic clamp technique (p-EHC) is applied to clinically normal Standardbred horses, and to monitor hoof wall temperature seeking an association between vascular activity and laminitis development. METHODS: Eight young, clinically normal Standardbred horses were assigned into 4 pairs and within each pair, one was assigned randomly to either treatment (n = 4) or control (n = 4) groups. Treated horses received continuous infusions of insulin and glucose until clinical signs of laminitis developed, at which point the horses were subjected to euthanasia. Control horses received an equivalent volume of a balanced electrolyte infusion for the same period. Hoof wall surface temperature (HWST) was monitored continuously throughout the experimental period. RESULTS: All horses in the treatment group were calculated to have normal insulin sensitivity. All treated horses, and none in the control group, developed laminitis (P = 0.01). Pronounced digital pulses were a feature of the treatment group, while insignificant digital pulses occurred in control horses. HWST was higher and less variable in treated horses once hyperinsulinaemia was established. CONCLUSIONS: Healthy Standardbred horses subjected to prolonged hyperinsulinaemia develop laminitis within 48 h, demonstrating that laminitis in horses can be triggered by insulin. POTENTIAL RELEVANCE: Insulin resistance and the associated hyperinsulinaemia place horses and ponies at risk of developing laminitis. This study demonstrates a need for prompt management of the persistent hyperinsulinaemia seen in some endocrinopathies.

Glucagon-like peptide-1, insulin-like growth factor-1, and adiponectin in insulin-dysregulated ponies: effects of feeding a high nonstructural carbohydrate diet and association with prospective laminitis.

Endocrinopathic laminitis, related to equine metabolic syndrome and insulin dysregulation, causes marked pain and suffering in horses and represents a substantial cost to the horse industry. This study investigated the effect of feeding a diet high in nonstructural carbohydrates on concentrations of active glucagon-like peptide-1 (aGLP-1), total insulin-like growth factor-1 (IGF-1), and high-molecular-weight (HMW) adiponectin, in insulin-dysregulated ponies. Thirty-seven ponies were challenged with this diet for up to 18 d to induce hyperinsulinemia. Hormone concentrations were measured in selected samples on day 2 of the diet challenge period, over 4 h after feeding. Fourteen of the ponies developed mild laminitis induced by the diet challenge. Insulin and glucose responses to the diet have been reported previously. Feeding increased the concentrations of aGLP-1 (P < 0.05) and HMW adiponectin (P < 0.001), but there was no difference between the laminitic and nonlaminitic groups for either hormone. Concentrations of IGF-1 and insulin were inversely related, with IGF-1 being 32% lower in hyperinsulinemic/laminitic ponies compared with nonlaminitic ponies (P = < 0.05). These results indicate that unlike insulin and possibly IGF-1, concentrations of aGLP-1 and HMW adiponectin do not have a strong association with, or play a major role in, the pathogenesis of equine laminitis.

Preliminary analysis of the FAM174A gene suggests it lacks a strong association with equine metabolic syndrome in ponies.

Equine metabolic syndrome (EMS) describes a group of risk factors, including obesity and insulin dysregulation (hyperinsulinemia and/or insulin resistance), that can lead to the development of the debilitating hoof disease laminitis. Although the underlying mechanisms of EMS are not fully understood, a genetic component has been reported, and an 11 guanine polymorphism located at the FAM174A gene has been identified as a risk locus for the syndrome in Arabian horses. To examine associations between the FAM174A risk allele and the clinical signs of EMS, the allele was examined in an Australian cohort of ponies (n = 20) with known metabolic status. The 11 guanine polymorphism was identified in only 3 of 13 ponies with EMS, and no significant association could be made between the risk loci and morphometric measurements associated with obesity (BCS [P = 0.21], cresty neck score [P = 0.58], basal triglyceride concentration [P = 0.85], and adiponectin concentration [P = 0.48]), or insulin dysregulation (insulin dysregulation status [P = 0.35] and serum insulin concentration during an oral glucose test [P = 0.44]). These results suggest that the FAM174A 11 guanine homopolymer allele is unlikely to be a singular key gene polymorphism associated with EMS in ponies. However, due to the small number of ponies identified with the polymorphism, further study of the FAM174A risk allele in a larger cohort of horses and ponies of uniform breed would be useful.

Ultrastructural examination of basement membrane pathology in horses with insulin-induced laminitis.

The third phalanx of the equine digit is suspended within the hoof capsule by a specialized interdigitating dermoepidermal layer called the lamellae, which fails during laminitis. Pathology of the basement membrane (BM), which interfaces epidermis and dermis, is evident during acute laminitis. However, BM damage appears to be less prevalent in ponies with the insulin-associated form of laminitis. The aim of the present study was to investigate changes to the ultrastructure and morphometry of the lamellar BM in the acute phase of insulin-induced laminitis in horses. Lamellar tissue from the left forefoot of 3 horses with acute hyperinsulinemic laminitis was examined with transmission electron microscopy and compared with tissue from normal horses. Lamellar BM width and hemidesmosome (HD) density were assessed every 5 µm along ∼200 µm of secondary epidermal lamellar BM. The BM zone of treated horses was extensively disorganized with loss of uniformity of the lamina lucida and lamina densa, fragmentation and disorientation of HDs, and cytoskeletal disengagement of the HDs. The mean (±SD) lamellar BM was twice as wide in treated (0.25 ± 0.05 µm), compared with control (0.14 ± 0.02 µm), horses. The HD density (HDs/µm) was reduced by half in the treatment group (1.88 ± 0.37), compared with controls (3.6 ± 0.13). The reduced number of HDs in horses with laminitis may contribute to the weakening of the dermoepidermal junction and lamellar failure. Disassembly of HDs during excessive cellular proliferation, secondary to hyperinsulinemia, may account for HD loss. Further investigation of the underlying etiopathogenesis of BM dysfunction during hyperinsulinemic laminitis in horses may facilitate an improved understanding of the disease.

Characterization of insulin and IGF-1 receptor binding in equine liver and lamellar tissue: implications for endocrinopathic laminitis.

Although it is well established that equine laminitis can be triggered by extreme hyperinsulinemia, the mechanism of insulin action is not known. High concentrations of insulin lead to separation of the weight-bearing apparatus from the hoof wall and are associated with an increased cycle of cell death and proliferation in the lamellae. Gene expression and immunohistochemistry studies have indicated that the lamellae are sparsely populated with insulin receptors, whereas IGF-1 receptors (IGF-1R) are abundant, suggesting that the action of insulin may be mediated by insulin binding to the IGF-1R. To investigate this possibility, cell membrane fragments containing IGF-1R were extracted from the livers of 6 horses and the lamellae of >50 horses euthanized for nonresearch purposes at an abattoir. Radioligand-binding studies using 125I-IGF-1 and 125I-insulin confirmed an abundance of high-affinity IGF-1R in the liver (KD 0.11 nM, Bmax 223 fmol/mg protein) and lamellae (KD 0.16 nM, Bmax 243 fmol/mg protein). However, the affinity of insulin for binding to the lamellar IGF-1R (Ki 934 nM) was >5,800 fold less than that of IGF-1, suggesting that insulin is unlikely to bind to equine IGF-1R at physiological concentrations. Although insulin receptors could be detected in the liver (KD 0.48 nM, Bmax 123 fmol/mg protein), they were barely detectable in lamellae (estimated Bmax 14 fmol/mg protein). There was no evidence to support the presence of insulin/IGF-1 hybrid receptors in either tissue. These findings suggest that insulin does not act directly through IGF-1 receptors and that an alternative theory is required to explain the mechanism of insulin action in laminitis.

Glucagon-like peptide-2: A potential role in equine insulin dysregulation.

BACKGROUND: Equine insulin dysregulation (ID) is a common and poorly understood disorder that increases the risk of laminitis. Recent data show that the condition may be associated with alteration of the enteroinsular axis and enhanced glucose bioavailability. Upregulation of glucagon-like peptide-2 (GLP-2), an intestinotrophic peptide, leads to enhanced nutrient uptake and metabolic dysfunction in other species. OBJECTIVES: The study aimed to 1) determine whether GLP-2 is differentially expressed in insulin-dysregulated ponies, compared with healthy ponies, and 2) confirm intestinal expression of the GLP-2 receptor in horses (eGLP-2R). STUDY DESIGN: Cohort study. METHODS: Fasting and post-prandial GLP-2 concentrations were measured in archived plasma samples obtained from 25 mixed-breed ponies during two feeding studies. Measurements were undertaken with an ELISA that was validated for equine use as part of the current study. Ponies were designated as healthy or insulin-dysregulated based on an oral glucose test, and the results were compared between groups. The gene expression of the eGLP-2R was determined with polymerase chain reaction. RESULTS: Basal, fasted plasma GLP-2 concentrations were higher in ponies with ID, compared with healthy ponies. Grazing increased GLP-2 in healthy, but not in insulin-dysregulated, ponies. The eGLP-2R gene was expressed in the small intestine and pancreas. MAIN LIMITATIONS: The study was performed with a relatively small sample size. The specificity of the GLP-2 assay could not be determined due to the lack of equine-specific assay standards. CONCLUSIONS: This study has demonstrated that GLP-2 may be important in the pathogenesis of equine ID and suggests that the eGLP-2R may be a novel therapeutic target for the treatment of equine ID.

The oral glucose test predicts laminitis risk in ponies fed a diet high in nonstructural carbohydrates.

The aim of this study was to investigate the relationship between laminitis development in ponies and insulin/glucose concentrations in response to the oral glucose test (OGT) and a dietary challenge high in nonstructural carbohydrates (NSCs). After undergoing an OGT (1 g dextrose/kg BW in feed), 37 ponies with 2-h serum insulin concentrations ranging from 22 to 1,133 µIU/mL were subjected to a diet challenge period (DCP), consuming 12 g NSC/kg BW/d for up to 18 d. Insulin and glucose responses were measured on day 2 of the DCP. Clinical laminitis was diagnosed by blinded experts and confirmed radiographically. Basal ACTH levels and clinical signs were assessed to investigate concurrent putative pituitary pars intermedia dysfunction (PPID). The diet induced Obel grade 1 or 2 laminitis in 14 ponies (38%). The ponies that developed laminitis had higher maximum concentrations of blood glucose (P = 0.04) and serum insulin (P = 0.02) in response to the diet. The geometric mean (95% CI) blood glucose concentration for laminitis cases was 14.9 (12.9-17.2) mM, compared to 10.7 (9.2-12.5) mM for ponies who did not develop laminitis. Similarly, the geometric mean (95% CI) for serum insulin was 396 (301-520) µIU/mL for laminitis cases, compared to 216 (148-316) µIU/mL for ponies who did not develop laminitis. Laminitis incidence was likewise associated with insulin concentrations measured during the OGT. Laminitis occurred at frequencies of 0% (0/7) if postdextrose insulin (µIU/mL) was <50; 35% (8/23) if insulin was 50 to 195; and 86% (6/7) if insulin was >195 µIU/mL. Basal ACTH concentrations were above seasonally accepted reference ranges in 16/37 ponies, and 8 of these animals (50%) developed laminitis. This included all 5 ponies in the study that had clinical signs of PPID (100%). In contrast, hyperinsulinemia and laminitis occurred in only 3/11 ponies (27%) with elevated ACTH concentrations and no clinical signs of PPID (P = 0.009). Thus, laminitis occurrence was associated with higher glucose and insulin responses to both the OGT and challenge diet, and the frequency of laminitis can be predicted based on insulin and glucose hyperresponsiveness to these oral carbohydrate challenges.