Variable ventilation ages in the equatorial Indian Ocean thermocline during the LGM

Variations of atmospheric CO₂ during the Pleistocene ice-ages have been associated with changes in the drawdown of carbon into the deep-sea. Modelling studies suggest that about one third of the glacial carbon drawdown may not be associated to the deep ocean, but to the thermocline or intermediate ocean. However, the carbon storage capacity of thermocline waters is still poorly constrained. Here we present paired ²³⁰Th/U and ¹⁴C measurements on scleractinian cold-water corals retrieved from ~ 450 m water depth off the Maldives in the Indian Ocean. Based on these measurements we calculate ∆¹⁴C, ∆∆¹⁴C and Benthic-Atmosphere (B_atm) ages in order to understand the ventilation dynamics of the equatorial Indian Ocean thermocline during the Last Glacial Maximum (LGM). Our results demonstrate a radiocarbon depleted thermocline as low as -250 to -345‰ (∆∆¹⁴C), corresponding to ~ 500-2100 years (B_atm) old waters at the LGM compared to ~ 380 years today. More broadly, we show that thermocline ventilation ages are one order of magnitude more variable than previously thought. Such a radiocarbon depleted thermocline can at least partly be explained by variable abyssal upwelling of deep-water masses with elevated respired carbon concentrations. Our results therefore have implications for radiocarbon-only based age models and imply that upper thermocline waters as shallow as 400 m depth can also contribute to some of the glacial carbon drawdown.

Higher incidence of stroke in severe COVID-19 is not associated with a higher burden of arrhythmias: comparison to other types of severe pneumonia

Background

Thromboembolic events, including stroke, are typical complications of COVID-19. Whether arrhythmias, frequently described in severe COVID-19, are disease-specific and thus promote strokes is unclear. We investigated the occurrence of arrhythmias, and stroke during rhythm monitoring in critically ill COVID-19, compared to severe pneumonias of other origin.

Methods

Recruited were 120 critically ill patients requiring mechanical ventilation in three European tertiary hospitals, including n=60 COVID-19, matched according to risk factors for occurrence of arrhythmias to n=60 patients from a retrospective consecutive cohort of severe pneumonias of other origin.

Results

Arrhythmias, mainly atrial fibrillation (AF), were frequent in COVID-19. However, when compared to nonCOVID-19, no difference was observed with respect to ventricular tachycardias (VT) and relevant bradyarrhythmias (VT 10.0 vs. 8.4%, p=ns and asystole 5.0 vs. 3.3%, p=ns) with consequent similar rates of cardiopulmonary resuscitation (6.7 vs. 10.0% p=ns). AF was even more common in nonCOVID-19 (AF 18.3 vs. 43.3%, p=0.003; newly onset AF 10.0 vs. 30.0%, p=0.006) which resulted in higher need for electrical cardioversion (6.7 vs. 20.0%, p=0.029). Despite these findings and comparable rates of therapeutic anticoagulation (TAC), the incidence of stroke was higher in COVID-19 (6.7.% vs. 0.0, p=0.042). These events happened also in absence of AF (50%) and with TAC (50%).

Conclusion

Arrhythmias were common in severe COVID-19, consisting mainly of AF, yet less frequent than in matched pneumonias of other origin. A contrasting higher incidence of stroke independent of arrhythmias observed also with TAC, seems to be an arrhythmia-unrelated disease-specific feature of COVID-19.

Funding Acknowledgement

Type of funding sources: None.

Binding of a TlCl Entity by a Tetragold Tetramercaptothiacalixarene Metalloligand via Metallophilic Interactions

The successive auration of p-tert-butyltetramercaptotetrathiacalix[4]arene, H₄ (MTC[4]), with gold(I) phosphine units was investigated. Through deprotonation with NaOMe, followed by salt metathesis reactions with (PR₃ )AuCl (R=Me, Ph) complexes with two and three [(PR₃ )Au]⁺ moieties could be prepared and isolated, namely [(Ph₃ PAu)₂ H₂ (MTC[4])] and [(Me₃ PAu)₃ H(MTC[4])]. In [(Me₃ PAu)₃ H(MTC[4])] two gold atoms already come close enough to undergo aurophilic interactions. To introduce a fourth [(PR₃ )Au]⁺ entity TlOEt had to be used for the deprotonation, which led to the finding that four gold atoms organised by the (MTC[4])^4- coordination platform are able to bind and stabilize a TlCl entity, yielding [(Me₃ PAu)₄ TlCl(MTC[4])]. As evidenced by structural and theoretical investigations the binding occurs through strong metallophilic interactions, which lead to photoluminescence at low temperatures.

Metabolic modeling using statistical and spreadsheet software: Application to the glucose minimal model

Kinetic non-linear metabolic models are used extensively in medical research and increasingly for clinical diagnostic purposes. An example of such a model is the Glucose Minimal Model by Bergman and colleagues [1]. This model is similar to pharmacokinetic/pharmacodynamic models in that like pharmacokinetic/pharmacodynamic models, it is based on a small number of fairly simple ordinary differential equations and it aims to determine how the changing concentration of one blood constituent influences the concentration of another constituent. Although such models may appear prima facie, to be relatively simple, they have gained a reputation of being difficult to fit to data, especially in a consistent and repeatable fashion. Consequently, researchers and clinicians have generally relied on dedicated software packages to do this type of modeling. This article describes the use of statistical and spreadsheet software for fitting the Glucose Minimal Model to data from an insulin modified intravenous glucose tolerance test (IM-IVGTT). A novel aspect of the modeling is that the differential equations that are normally used to describe insulin action and the disposition of plasma glucose are first solved and expressed in their explicit forms so as to facilitate the estimation of Glucose Minimal Model parameters using the nonlinear (nl) optimization procedure within statistical and spreadsheet software. The most important clinical parameter obtained from the Glucose Minimal Model is insulin sensitivity (S_I). Using IM-IVGTT data from 42 horses in one experiment and 48 horses in a second experiment, we demonstrate that estimates of S_I derived from the Glucose Minimal Model fitted to data using STATA and Excel, are highly concordant with S_I estimates obtained using the industry standard software, MinMod Millennium. This work demonstrates that there is potential for statistical and spreadsheet software to be applied to a wide range of kinetic non-linear modeling problems.

Diagnosis and treatment of confirmed and suspected primary hyperparathyroidism in equids: 17 cases (1999-2016)

BACKGROUND

Primary hyperparathyroidism is uncommon in equids.

OBJECTIVES

To describe the diagnostic findings and efficacy of treatment in equids with primary hyperparathyroidism.

STUDY DESIGN

Retrospective case series describing 16 horses and one mule.

METHODS

Cases were identified by retrospective review of records at Cornell University and via an ACVIM listserv query. Inclusion criteria were an equid with hypercalcemia, normal renal function and high parathyroid hormone (PTH) or histopathological diagnosis of a parathyroid adenoma. Equids with normal PTH and PTH-related protein (PTHrP) in the face of hypercalcemia were included as suspect cases.

RESULTS

The most common presenting complaints were weight loss (12/17) and hypercalcemia (10/17). PTH was above reference range in 12/17 cases. Suspected parathyroid tumours were localised in 12/14 equids imaged using ultrasonography alone (2/3), technetium 99m Tc sestamibi scintigraphy alone (1/1) or both modalities (9/10). Three horses did not have imaging performed. Surgical exploration successfully excised tumours in six of 10 cases. Five were located at the thoracic inlet, and surgery resulted in complete cure. One tumour was excised from the thyroid lobe, and the horse remained hypercalcemic. Four other cases explored surgically, four treated medically and three that were not treated also remained hypercalcemic.

MAIN LIMITATIONS

The small study size prohibited statistical analysis.

CONCLUSIONS

Parathyroid adenomas in equids can be successfully localised with ultrasonography and scintigraphy. Surgical excision appears more likely to be successful for single gland disease at the thoracic inlet.

Role of heme modulation in inhibition of Atheris, Atractaspis, Causus, Cerastes, Echis, and Macrovipera hemotoxic venom activity

Venomous snake bite and subsequent coagulopathy is a significant source of morbidity and mortality worldwide. The gold standard to treat coagulopathy caused by these venoms is the administration of antivenom; however, despite this therapy, coagulopathy still occurs and recurs. Of interest, our laboratory has demonstrated in vitro and in vivo that coagulopathy-inducing venom exposed to carbon monoxide (CO) is inhibited, potentially by an attached heme. The present investigation sought to determine if venoms derived from snakes of the African genera Atheris, Atractaspis, Causus, Cerastes, Echis, and Macrovipera that have no or limited antivenoms available could be inhibited with CO or with the metheme-inducing agent, O-phenylhydroxylamine (PHA). Assessing changes in coagulation kinetics of human plasma with thrombelastography, venoms were exposed in isolation to CO or PHA. Eight species were found to have procoagulant activity consistent with the generation of human thrombin, while one was likely fibrinogenolytic. All venoms were significantly inhibited by CO/PHA with species-specific variation noted. These data demonstrate indirectly that the heme is likely bound to these disparate venoms as an intermediary modulatory molecule. In conclusion, future investigation is warranted to determine if heme could serve as a potential therapeutic target to be modulated during treatment of envenomation by hemotoxic enzymes.

Repeatability of Oral Sugar Test Results, Glucagon-Like Peptide-1 Measurements, and Serum High-Molecular-Weight Adiponectin Concentrations in Horses

BACKGROUND

Repeatability of the oral sugar test (OST) has not been evaluated.

OBJECTIVES

We hypothesized that OST glucose, insulin, active (aGLP-1) and total (tGLP-1) glucagon-like peptide 1, and high-molecular-weight (HMW) adiponectin results would be repeatable.

ANIMALS

Fifty-three horses from a Tennessee research facility (n = 23) and private practice in Missouri (n = 30), including animals with medical histories of equine metabolic syndrome.

METHODS

Two OSTs were performed 7-14 days apart and plasma glucose and insulin concentrations were measured at 0, 60, and 75 minutes; a positive result was defined as detection of an insulin concentration >45 μU/mL at 60 or 75 minutes. Plasma aGLP-1 and serum tGLP-1 concentrations at 75 minutes and serum HMW adiponectin concentrations at 0 minute were measured in the Missouri group. Bland-Altman analyses were performed.

RESULTS

No adverse events were reported. Bland-Altman analysis indicated mean ± SD bias of 1.5 ± 14.8 μU/mL (95% confidence interval [CI], -27.6 to 30.5 μU/mL) and 1.2 ± 16.1 μU/mL (95% CI, -30.4 to 32.8 μU/mL) for insulin concentrations at 60 and 75 minutes, respectively. There was 91 and 83% agreement in test interpretation between test days for OST insulin results for all horses in the Tennessee and Missouri groups, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

Repeatability of the OST was acceptable when values obtained from Bland-Altman analyses were evaluated, and there was good agreement in binary (negative/positive) test interpretation for insulin concentrations. However, wide 95% CIs were detected for insulin concentrations.

Blood Glucose and Insulin Concentrations after Octreotide Administration in Horses With Insulin Dysregulation

Background

Octreotide is a somatostatin analog that suppresses insulin secretion.

Hypothesis

We hypothesized that octreotide would suppress insulin concentrations in horses and that normal (N) horses and those with insulin dysregulation (ID) would differ significantly in their plasma glucose and insulin responses to administration of octreotide.

Animals

Twelve horses, N = 5, ID = 7.

Methods

Prospective study. An oral sugar test was performed to assign horses to N and ID groups. Octreotide (1.0 μg/kg IV) was then administered, and blood was collected at 0, 5, 10, 15, 20, 25, 30, 45, 60, 75, and 90 minute, and 2, 3, 4, 6, 8, 12, and 24 hour for measurement of glucose and insulin concentrations. Area under the curve (AUC) values were calculated.

Results

Mean AUC values for glucose and insulin did not differ between normal (n = 5) and ID (n = 7) groups after octreotide injection. Significant time (P < .001) effects were detected for glucose and insulin concentrations. A group × time interaction (P = .091) was detected for insulin concentrations after administration of octreotide, but the group (P = .33) effect was not significant.

Conclusions and Clinical Importance

Octreotide suppresses insulin secretion, resulting in hyperglycemia, and then concentrations increase above baseline as glycemic control is restored. Our hypothesis that octreotide causes insulin concentrations to decrease in horses was supported, but differences between N and ID groups did not reach statistical significance when blood glucose and insulin responses were compared. The utility of an octreotide response test remains to be determined.

Is a Routine Chest X-ray Necessary in Every Patient After Percutaneous CT-Guided Lung Biopsy? A Retrospective Review of 278 Cases

PURPOSE

To determine the rate, clinical significance, and predictors of delayed pneumothorax after CT-guided lung biopsy.

METHODS

Medical and imaging records of all patients who underwent CT-guided lung biopsy between January 1, 2012, and January 9, 2015, were reviewed. "Early pneumothorax" was defined as one visualized on CT scan at the time of biopsy, "delayed pneumothorax" as one discovered on the first follow-up chest X-ray (CXR), and "clinically significant pneumothorax" as one requiring chest tube placement.

RESULTS

Three hundred fifty-seven lung biopsies were performed; 79 patients did not have follow-up CXR and were excluded. Out of 278 cases included in the study, early pneumothorax occurred in 109 patients. Follow-up CXRs were available in the remaining 169 patients without early pneumothorax and were obtained 3.1 ± 2.9 h after biopsy. The rate of delayed pneumothorax was 8.6% (24/278). Clinically significant pneumothorax occurred in 10/24 (41.7%) patients with delayed pneumothorax, including one case of tension pneumothorax. Patients with delayed pneumothorax (n = 24) had smaller lesion long axial diameter (18.58 ± 9.84 vs 25.83 ± 17.69 mm, p = 0.005), longer intrapulmonary needle tract (23.45 ± 14.98 vs 14.17 ± 14.49, p = 0.004), and lower FEV1/FVC ratio (53.30 ± 22.47 vs 71.15 ± 13.77, p = 0.015), compared to those without delayed pneumothorax (n = 145). The length of intrapulmonary needle tract was the only independent predictor of delayed pneumothorax (p = 0.008) and symptomatic delayed pneumothorax (p = 0.019).

CONCLUSION

Obtaining a routine follow-up CXR in all patients after CT-guided lung biopsy appears warranted, given the high rate of delayed pneumothorax and large percentage of patients who will require a chest tube. The only independent predictor of (symptomatic) delayed pneumothorax was the length of intrapulmonary needle tract.

In Vivo Development of Transplant Arteriosclerosis in Humanized Mice Reflects Alloantigen Recognition and Peripheral Treg Phenotype of Lung Transplant Recipients

Experimentally, regulatory T cells inhibit rejection. In clinical transplantations, however, it is not known whether T cell regulation is the cause for, or an epiphenomenon of, long-term allograft survival. Here, we study naïve and alloantigen-primed T cell responses of clinical lung transplant recipients in humanized mice. The pericardiophrenic artery procured from human lung grafts was implanted into the aorta of NODrag^-/- /IL-2rγc^-/- mice reconstituted with peripheral blood mononuclear cells (PBMCs) from the respective lung recipient. Naïve or primed allogeneic PBMCs procured 21 days post-lung transplantation with or without enriching for CD4⁺ CD25^high T cells were used. Transplant arteriosclerosis was assessed 28 days later by histology. Mice reconstituted with alloantigen-primed PBMCs showed significantly more severe transplant arteriosclerosis than did mice with naïve PBMCs (p = 0.005). Transplant arteriosclerosis was equally suppressed by enriching for autologous naïve (p = 0.012) or alloantigen-primed regulatory T cells (Tregs) (p = 0.009). Alloantigen priming in clinical lung recipients can be adoptively transferred into a humanized mouse model. Transplant arteriosclerosis elicited by naïve or alloantigen-primed PBMCs can be similarly controlled by potent autologous Tregs. Cellular therapy with expanded autologous Tregs in lung transplantation might be a promising future strategy.

Relevance of flow cytometric enumeration of post-thaw leucocytes: influence of temperature during cell staining on viable cell recovery

BACKGROUND AND OBJECTIVES

Our post-thaw cell recovery rates differed substantially in interlaboratory comparisons of identical samples, potentially due to different temperatures during cell staining.

MATERIALS AND METHODS

Viable CD34(+) cells and leucocyte (WBC) subtypes were quantified by multiparameter single-platform flow cytometry in leucapheresis products collected from 30 adult lymphoma and myeloma patients, and from 10 paediatric patients. After thawing, cells were prepared for analysis within 30 min between thawing and acquisition, at either 4°C or at room temperature.

RESULTS

For cell products cryopreserved in conventional freezing medium (10% final DMSO), viable cell recovery was clearly lower after staining at 4°C than at RT. Of all WBC subtypes analysed, CD4(+) T cells showed the lowest median recovery of 4% (4°C) vs. 25% (RT), followed by CD3, CD34 and CD8 cells. The recovery was highest for CD3γδ cells with 44% (4°C) vs. 71% (RT). In the 10 samples cryopreserved in synthetic freezing medium (5% final DMSO), median recovery rates were 89% for viable CD34 (both at 4°C and RT) and 79% (4°C) vs 68% (RT) for WBC.

CONCLUSIONS

The post-thaw environment and, potentially, the cryoprotectant impact the outcome of cell enumeration, and results from the analysis tube may not be representative of the cells infused into a patient.

Effect of Age, Season, Body Condition, and Endocrine Status on Serum Free Cortisol Fraction and Insulin Concentration in Horses

BACKGROUND

Increased free cortisol fraction is associated with insulin dysregulation (ID) in people with Metabolic Syndrome and Cushing's Disease. Free cortisol has not been investigated in equine endocrine disorders.

HYPOTHESES

(1) In healthy horses, sex, age, body condition score (BCS), and season impact free cortisol; (2) free cortisol is increased in horses with Pituitary Pars Intermedia Dysfunction (PPID) or Equine Metabolic Syndrome (EMS).

ANIMALS

Fifty-seven healthy horses; 40 horses and ponies with PPID (n = 20) or EMS (n = 20).

METHODS

Prospective study. Serum collected seasonally from healthy animals and archived serum from PPID and EMS animals was analyzed for insulin, total and free cortisol concentrations, and free cortisol fraction (FCF). Linear mixed models were used to determine effects of age, sex, season, and BCS on hormones in controls. Hormone measurements were compared between disease groups and age- and season-matched controls with t-tests. EMS and hyperinsulinemic PPID animals were combined in an ID (hyperinsulinemia) group.

RESULTS

Free cortisol concentrations were increased in overweight/obese controls (0.3 ± 0.1 μg/dL) compared to lean controls (0.2 ± 0.1 μg/dL; P = .017). Mean FCF was significantly higher in animals with PPID (8.8 ± 5.8 μg/dL, P = .005) or ID (8.8 ± 10.2 μg/dL, P = .039) than controls (5.0 ± 0.9 μg/dL), but total cortisol concentrations were similar (P ≥ .350) (PPID: 4.2 ± 4.3 μg/dL; ID: 5.0 ± 4.5 μg/dL; controls: 4.6 ± 1.7 and 5.1 ± 2.1 μg/dL).

CONCLUSIONS AND CLINICAL IMPORTANCE

Increased FCF is associated with obesity in healthy horses and with ID (hyperinsulinemia) in horses and ponies with endocrine disease. Decreased plasma cortisol-binding capacity could be a component of these endocrine disorders in horses.

Insulin dysregulation

Abnormalities of insulin metabolism include hyperinsulinaemia and insulin resistance, and these problems are collectively referred to as insulin dysregulation in this review. Insulin dysregulation is a key component of equine metabolic syndrome: a collection of endocrine and metabolic abnormalities associated with the development of laminitis in horses, ponies and donkeys. Insulin dysregulation can also accompany prematurity and systemic illness in foals. Causes of insulin resistance are discussed, including pathological conditions of obesity, systemic inflammation and pituitary pars intermedia dysfunction, as well as the physiological responses to stress and pregnancy. Most of the discussion of insulin dysregulation to date has focused on insulin resistance, but there is increasing interest in hyperinsulinaemia itself and insulin responses to feeding. An oral sugar test or in-feed oral glucose tolerance test can be performed to assess insulin responses to dietary carbohydrates, and these tests are now recommended for use in clinical practice. Incretin hormones are likely to play an important role in postprandial hyperinsulinaemia and are the subject of current research. Insulin resistance exacerbates hyperinsulinaemia, and insulin sensitivity can be measured by performing a combined glucose-insulin test or i.v. insulin tolerance test. In both of these tests, exogenous insulin is administered and the rate of glucose uptake into tissues measured. Diagnosis and management of hyperinsulinaemia is recommended to reduce the risk of laminitis. The term insulin dysregulation is introduced here to refer collectively to excessive insulin responses to sugars, fasting hyperinsulinaemia and insulin resistance, which are all components of equine metabolic syndrome.

Study of two-neutron radioactivity in the decay of 26O

A new technique was developed to measure the lifetimes of neutron unbound nuclei in the picosecond range. The decay of 26O→24O+n+n was examined as it had been predicted to have an appreciable lifetime due to the unique structure of the neutron-rich oxygen isotopes. The half-life of 26O was extracted as 4.5(-1.5)(+1.1)(stat)±3(syst)  ps. This corresponds to 26O having a finite lifetime at an 82% confidence level and, thus, suggests the possibility of two-neutron radioactivity.

When biological scientists become health-care workers: emotional labour in embryology

STUDY QUESTION

Can biological scientists working in medically assisted reproduction (MAR) have a role as health-care workers and, if so, how do they engage in the emotional labour commonly associated with health-care work?

SUMMARY ANSWER

The scientists at Fertility Associates (FA) in New Zealand perform the technical and emotional cares associated with health-care work in an occupationally specific manner, which we refer to as a hybrid care style. Their emotional labour consists of managing difficult patients, 'talking up' bad news, finding strategies to sustain hope and meaning, and 'clicking' or 'not clicking' with individual patients.

WHAT IS KNOWN ALREADY

Effective emotional labour is a key component of patient-centred care and is as important to the experience of high-quality MAR as excellent clinical and scientific technique.

STUDY DESIGN, SIZE, DURATION

This is a qualitative study based on open-ended interviews and ethnographic observations with 14 staff in 2 laboratories conducted over 2 separate periods of 3 weeks duration in 2007. Analysis of fieldnotes and interviews was conducted using thematic analysis and an NVivo qualitative database and compared for consistency across each interviewer.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The participants were consenting biological scientists working in one of the two laboratories. Semi-structured interviews were conducted in 'quiet' work times, and supervised access was allowed to all parts of the laboratories and meeting places. Opportunities for participant review of results and cross comparison of independent analysis by authors increases the faithfulness of fit of this account to laboratory life.

MAIN RESULTS AND THE ROLE OF CHANCE

The study suggests that emotional labour is a part of routinized scientific labour in MAR laboratories for FA.

LIMITATIONS, REASONS FOR CAUTION

This is a qualitative study and thus the findings are not generalizable to populations beyond the study participants.

WIDER IMPLICATIONS OF THE FINDINGS

While little has been published of the emotional component of scientist's working lives, there may be a New Zealand style of doing scientific work in MAR laboratories which is patient centred and which incorporates much higher patient contact and involvement than is experienced in other laboratories.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by a research grant from the University of Otago and was also partly funded by a Marsden Grant administered by the Royal Society of New Zealand.

TRIAL REGISTRATION NUMBER

N/A.

Evidence for the ground-state resonance of 26O

Evidence for the ground state of the neutron-unbound nucleus (26)O was observed for the first time in the single proton-knockout reaction from a 82 MeV/u (27)F beam. Neutrons were measured in coincidence with (24)O fragments. (26)O was determined to be unbound by 150(-150)(+50) keV from the observation of low-energy neutrons. This result agrees with recent shell-model calculations based on microscopic two- and three-nucleon forces.

First observation of ground state dineutron decay: 16Be

We report on the first observation of dineutron emission in the decay of 16Be. A single-proton knockout reaction from a 53  MeV/u 17B beam was used to populate the ground state of 16Be. 16Be is bound with respect to the emission of one neutron and unbound to two-neutron emission. The dineutron character of the decay is evidenced by a small emission angle between the two neutrons. The two-neutron separation energy of 16Be was measured to be 1.35(10) MeV, in good agreement with shell model calculations, using standard interactions for this mass region.

Exploring the low-Z shore of the island of inversion at n=19

The technique of invariant mass spectroscopy has been used to measure, for the first time, the ground state energy of neutron-unbound (28)F, determined to be a resonance in the (27)F+n continuum at 220(50) keV. States in (28)F were populated by the reactions of a 62 MeV/u (29)Ne beam impinging on a 288 mg/cm(2) beryllium target. The measured (28)F ground state energy is in good agreement with USDA/USDB shell model predictions, indicating that pf shell intruder configurations play only a small role in the ground state structure of (28)F and establishing a low-Z boundary of the island of inversion for N=19 isotones.

Effects of a supplement containing chromium and magnesium on morphometric measurements, resting glucose, insulin concentrations and insulin sensitivity in laminitic obese horses

REASONS FOR PERFORMING STUDY

Obesity and insulin resistance are risk factors for laminitis in equids and supplements containing chromium and magnesium might improve insulin sensitivity.

HYPOTHESIS

A supplement containing chromium, magnesium and other nutraceuticals would alter morphometric measurements, blood variables, and insulin sensitivity in laminitic obese horses.

METHODS

Twelve previously laminitic obese (body condition score ≥ 7/9) horses were randomly allocated to treatment (n = 6) and control (n = 6) groups and 2 obese horses with clinical laminitis were included in the treatment group. Treated animals received 56 g supplement with 0.25 kg oats once daily for 16 weeks. The supplement contained chromium (5 mg/day as yeast), magnesium (8.8 g/day as oxide/proteinate), and other nutraceuticals. Insulin-modified frequently sampled i.v. glucose tolerance tests were performed with hay provided at 0, 8 and 16 weeks, and insulin sensitivity was estimated by minimal model analysis. Physical measurements were collected at the same points. Horses were not exercised.

RESULTS

Hyperinsulinaemia (>30 µu/ml) was detected in 12 of 14 horses prior to treatment. Glucose and insulin data from one mare with clinical laminitis were excluded because of persistent pain. Mean ± s.d. insulin sensitivity was 0.64 ± 0.62 × 10(-4) l/min/mu prior to treatment for the remaining 13 horses. Time and treatment × time effects were not significant for any of the variables examined, with the exception of resting insulin concentrations, which significantly increased over time (P = 0.018). Health status remained the same.

CONCLUSIONS

The supplement containing chromium and magnesium evaluated in this study did not alter morphometric measurements, blood variables, resting insulin concentrations or insulin sensitivity in laminitic obese horses.

POTENTIAL RELEVANCE

Additional research is required to determine the appropriate use of chromium and magnesium supplements in horses.

Effects of endotoxaemia and carbohydrate overload on glucose and insulin dynamics and the development of laminitis in horses

REASONS FOR PERFORMING STUDY

Insulin resistance (IR) is a risk factor for pasture-associated laminitis in equids and alimentary carbohydrate overload may trigger laminitis. Whether glucose metabolism responses to carbohydrate overload are more pronounced in insulin-resistant horses requires further study.

HYPOTHESIS

Horses pretreated with endotoxin to alter insulin sensitivity differ significantly in their glucose and insulin responses to carbohydrate overload.

METHODS

Horses (n=24) were divided into 3 groups. A lipopolysaccharide (LPS; n=8) group that received endotoxin as an 8 h 7.5 ng/kg bwt/h i.v. continuous rate infusion, an oligofructose (OF; n=8) group that received an infusion of saline followed by 5 g/kg bwt OF via nasogastric intubation, and a LPS/OF (n=8) group that received LPS followed 16 h later by OF. Glucose and insulin dynamics were evaluated at -24 h and 48 h using the frequently sampled i.v. glucose tolerance test and minimal model analysis. Physical examinations and haematology were performed and the severity of laminitis assessed.

RESULTS

Horses receiving LPS developed leucopenia and both LPS and OF induced clinical signs consistent with systemic inflammation. Insulin sensitivity significantly decreased (P < 0.001) over time, but responses did not differ significantly among groups. Time (P < 0.001) and treatment x time (P = 0.038) effects were detected for the acute insulin response to glucose, with mean values significantly increasing in LPS and LPS/OF groups, but not the OF group. Five horses in the LPS/OF group developed clinical laminitis compared with 0 and 2 horses in the LPS and OF groups, respectively.

CONCLUSIONS

Endotoxaemia and carbohydrate overload reduce insulin sensitivity in horses. Endotoxin pretreatment does not affect the alterations in glucose metabolism induced by carbohydrate overload.

POTENTIAL RELEVANCE

Insulin sensitivity decreases after carbohydrate overload in horses, which may be relevant to the development of pasture-associated laminitis.