Associations between training characteristics and change in peak oxygen consumption following exercise training in patients with heart failure with preserved ejection fraction

Introduction

In heart failure with preserved ejection fraction (HFpEF), moderate continuous training (MCT) and high-intensity interval training (HIIT) are both effective in increasing peak oxygen uptake (peak V̇O2).

Purpose

The aim of this study was to investigate the association of training characteristics (i.e. average sessions/week, average duration/week, mean intensity) and change in peak V̇O2 following 3 months of MCT and HIIT in patients with HFpEF.

Methods

Among 120 patients who were randomized to MCT (5x40 min/week at 35–50% heart rate reserve [HRR]) or HIIT (3x38 min/week at 80–90% HRR), those who completed 3-month follow-up (N=107) were considered for this analysis. Training duration and heart rates [HR] were recorded with a smartphone application, evaluated with a customized software and manually checked for plausibility. If HR measurements were classified as invalid/unreliable (e.g. very strong fluctuations), patients were excluded from analysis. Intensities were calculated as average % HRR of total sessions in MCT and the average of the highest % HRR values of all intervals in HIIT. Associations between training characteristics and change in peak V̇O2 were evaluated using univariate and multivariate regression analyses. Individual HR-V̇O2 relationships were used to calculate and compare energy expenditure (MET-minutes) in MCT and HIIT.

Results

After excluding 16 patients due to invalid/unreliable HR data, 91 patients (67% female, 69±7 years) were included in this analysis. On average, MCT patients (N=45) performed 4.0±1.2 sessions/week (162±52 min/week) at 47.4±6.7% HRR, while HIIT patients (N=46) performed 2.4±0.8 sessions/week (96±40 min/week) at 81.8±11.8% HRR. Peak V̇O2 was improved by 1.70±2.35 ml/kg/min in MCT and 1.46±2.98 ml/kg/min in HIIT (difference: 0.24 [95% CI, −0.87 to 1.34], p=0.67). The associations between training characteristics and change in peak V̇O2 are shown in Fig.1. Mean % HRR was not significantly associated with the change in peak V̇O2 in the HIIT group, whereas in MCT, mean duration/week and mean intensity were of similar relative importance (standardized coefficients) and explained up to 26% of the variation in change in peak V̇O2 (Table 1). Average weekly MET-minutes above rest were 451±260 for MCT and 389±375 for HIIT (difference: 62 [95% CI, −71 to 195], p=0.36). After adjustment for MET-minutes, the difference in change in peak V̇O2 between groups diminished to 0.09 ml/kg/min (95% CI, −0.97 to 1.16; p=0.98).

Conclusions

Weekly duration and mean % HRR had a similar predictive ability for the change in peak V̇O2 following MCT with, interestingly, lower change in peak V̇O2 with increasing intensity. In HIIT, mean % HRR was not significantly associated with the change in peak V̇O2. After adjusting for energy expenditure, the difference in change in peak V̇O2 between training modes diminished, suggesting that MCT and HIIT were similarly effective.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Commission, Framework Program 7

Effect of exercise training on vascular function and endothelial repair in heart failure with preserved ejection fraction: results from the OptimEx trial

Background

Exercise training improves peak oxygen uptake (VO2) in heart failure with preserved ejection fraction (HFpEF), but the underlying mechanisms are unknown. In other cardiovascular diseases, exercise training improves vascular function and increases levels of circulating endothelium-repairing cells. We aimed to investigate the effects of moderate continuous training (MCT) and high intensity interval training (HIIT) on vascular function and cellular endothelial repair in HFpEF.

Methods

This was a prespecified subanalysis of the Optimizing Exercise Training in Prevention and Treatment of Diastolic Heart Failure randomized trial. HFpEF patients (n=180) were randomized to HIIT, MCT or attention control. At baseline and after 12 weeks, we measured peak VO2, fingertip arterial tonometry (n=109), brachial artery flow-mediated dilation (n=59), aortic pulse wave velocity (n=94), and flow cytometry (n=136) for endothelial progenitor cells (CD45dimCD34+VEGFR2+) and angiogenic T cells (CD3+CD31+CD184+). Changes in these parameters were compared between groups using linear mixed models. Parameters were correlated using Spearman's rho.

Results

At 3 months, we did not observe significant differences between HIIT, MCT and control group regarding changes in vascular function throughout the vascular tree (fingertip arterial tonometry, brachial artery flow-mediated dilation and central arterial stiffness, Table 1) or levels of circulating endothelium-repairing cells (endothelial progenitor cells and angiogenic T cells, Table 1). Results were similar at 12 months and when restricting analysis to patients with at least 70% adherence to training sessions. Patients with higher peak VO2 at baseline had lower numbers of circulating endothelial progenitor cells (rho=−0.22, p=0.011).

Conclusions

In patients with HFpEF, exercise training did not change vascular function or levels of endothelium-repairing cells. Thus, improved vascular function likely does not contribute to the change in peak VO2 after training. These findings are in contrast with the benefits of exercise on vascular function in heart failure with reduced ejection fraction and coronary artery disease.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): EU Framework Programme 7 Table 1

GLP-1 is an independent predictor of long-term mortality in patients with myocardial infarction complicated by cardiogenic shock – a substudy of the IABP-SHOCK II trial

Background

The incretin hormone Glucagon-like-peptide 1 (GLP-1) is a major stimulus for glucose dependent insulin secretion and holds cardioprotective efficacy. This has made the GLP-1 system a preferred target for diabetes therapy. Secretion of GLP-1 happens in response to nutritional but also inflammatory stimuli. Consequently, marked elevation of circulating GLP-1 levels were found in critically ill patients featuring marked association to markers of inflammation.

Purpose

Our study sought to investigate GLP-1 levels in patients with cardiogenic shock (CS) complicating myocardial infarction and a possible prognostic correlation to short- and long-term outcome.

Methods

We serially assessed circulating GLP-1 levels in a prospectively planned biomarker substudy in the IABP-SHOCK II trial. Blood samples were drawn during index PCI and at day 2. The blood was centrifuged immediately, and serum was frozen at −87°C. GLP-1 was measured with a standard ELISA-kit. All-cause mortality at short- (30 days), intermediate- (1 year) and long-term (6 years) follow-up was used for outcome assessment.

Results

In this study we found circulating GLP-1 to be markedly elevated in patients with myocardial infarction complicated by CS (n=172) at time of index PCI. Patients with fatal short-term outcome (n=70) exhibited higher GLP-1 levels (86 [45–130] pM) at ICU admission in comparison to patients with 30-day survival (48 [33–78] pM; p<0.001) (n=102). In repeated measures ANOVA the course of GLP-1 levels between baseline and day 2 showed a significant interaction between survivors and non-survivors (p=0.04). By univariate Cox-regression analysis GLP-1 levels >median were predictive of short- (hazard ratio [HR] 2.43; 95% confidence interval [CI] 1.50–3.94; p<0.001), intermediate- (HR 2.46; 95% CI 1.62–3.76; p<0.001) and long-term (HR 2.12; 95% CI 1.44–3.11; p<0.001) outcome. This association remained after multivariable correction (HR 2.01; 95% CI 1.37–3.07; p<0.001). In a landmark analysis we found a significant higher mortality in patients with GLP-1 levels >median from day 30 to 1 year (HR 2.56; 95% CI 1.08–6.09; p=0.03). In contrast, beyond 1 year up to 6 years no difference has been observed anymore (HR 1.02; 95% CI 0.41–2.58; p=0.96).

Conclusions

Elevated plasma levels of GLP-1 are an independent predictor for impaired prognosis in patients with myocardial infarction complicated by CS at short-, intermediate and long-term follow-up. In a landmark analysis this prognostic effect is sustained up to 1 year. The functional relevance of GLP-1 in this context is currently unknown and needs further investigations.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): German Research Foundation (DFG), German Heart Research Foundation

Randomised, cOntrolled Multicentre trial of 26 weeks subcutaneous liraglutide (a glucagon-like peptide-1 receptor Agonist), with or without contiNuous positive airway pressure (CPAP), in patients with type 2 diabetes mellitus (T2DM) and obstructive sleep apnoEa (OSA) (ROMANCE): study protocol assessing the effects of weight loss on the apnea-hypnoea index (AHI)

INTRODUCTION

Obstructive sleep apnoea (OSA) and type 2 diabetes mellitus (T2DM) often occur concurrently, and untreated OSA may potentially amplify the high risk of cardiovascular disease in T2DM. Compliance with continuous positive airway pressure (CPAP), the conventional treatment for OSA, can be poor and considering weight loss is the most effective treatment for OSA. This trial examines whether the glucagon-like peptide-1 receptor agonist liraglutide, a glucose-lowering therapy associated with significant weight loss used in T2DM, can improve the severity and symptoms of OSA.

METHODS AND ANALYSIS

This is an outpatient, single-centred, open-labelled, prospective, phase IV randomised controlled trial in a two-by-two factorial design. One hundred and thirty-two patients with newly diagnosed OSA (apnoea-hypopnoea index (AHI) ≥15 events/hour), and existing obesity and T2DM (glycated haemoglobin (HbA_1c) ≥47 mmol/mol), will be recruited from diabetes and sleep medicine outpatient clinics in primary and secondary care settings across Liverpool. Patients will be allocated equally, using computer-generated random, permuted blocks of unequal sizes, to each of the four treatment arms for 26 weeks: (i) liraglutide (1.8 mg once per day) alone, (ii) liraglutide 1.8 mg once per day with CPAP, (iii) CPAP alone (conventional care) or (iv) no treatment (control). The primary outcome measure is change in OSA severity, determined by AHI. Secondary outcome measures include effects on glycaemic control (glycated haemoglobin (HbA1c)), body weight and quality of life measures. Exploratory measures include measures of physical activity, MRI-derived measures of regional body composition including fat mass (abdominal subcutaneous, visceral, neck and liver fat) and skeletal muscle mass (cross-sectional analysis of thigh), indices of cardiac function (using transthoracic echocardiography) and endothelial function.

ETHICAL APPROVAL

The study has been approved by the North West Liverpool Central Research Ethics Committee (14/NW/1019) and it is being conducted in accordance with the Declaration of Helsinki and Good Clinical Practice.

TRIAL REGISTRATION NUMBERS

ISRCTN16250774. EUDRACT No. 2014-000988-41. UTN U1111-1139-0677.

The effect of methyl and methoxy substituents on dianilines for a thermosetting polyimide system

4,4′-Methylenedianiline (MDA) is widely used in high-temperature polyimide resins, including polymerization of monomer reactants-15. The toxicity of MDA significantly limits the manufacturability using this resin. Modifying the substitution and electronics of MDA could allow for the reduction of toxicity while maintaining the high-performing properties of the materials derived from the modified MDA. The addition of a single methyl substituent, methoxy substituent, location of these substituents, and location of the amine relative to the phenolic bridge were modified as were other non-aniline diamines. Various anilines were condensed with paraformaldehyde under acidic conditions to yield dianilines. These dianilines and diamines were reacted with nadic anhydride and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride in methanol to form the polyamic acid oligomers and heated at elevated temperature to form polyimide oligomers. It was found that the molecular weight of the oligomers derived from MDA alternatives was generally lower than that of MDA oligomers resulting in lower glass transition temperatures ( T gs) and degradation temperatures. Additionally, methoxy substituents further reduce the T g of the polymers versus methyl substituents and reduce the thermal stability of the resin. Methyl-substituted alternatives produced polyimides with similar T gs and degradation temperatures. The toxicity of the MDA alternatives was examined. Although a few were identified with reduced toxicities, the alternatives with properties similar to that of MDA also had high toxicities.

Resting-state functional brain networks in adults with a new diagnosis of focal epilepsy

OBJECTIVES

Newly diagnosed focal epilepsy (NDfE) is rarely studied, particularly using advanced neuroimaging techniques. Many patients with NDfE experience cognitive impairments, particularly with respect to memory, sustained attention, mental flexibility, and executive functioning. Cognitive impairments have been related to alterations in resting-state functional brain networks in patients with neurological disorders. In the present study, we investigated whether patients with NDfE had altered connectivity in large-scale functional networks using resting-state functional MRI.

METHODS

We recruited 27 adults with NDfE and 36 age- and sex-matched healthy controls. Resting-state functional MRI was analyzed using the Functional Connectivity Toolbox (CONN). We investigate reproducibly determined large-scale functional networks, including the default mode, salience, fronto-parietal attention, sensorimotor, and language networks using a seed-based approach. Network comparisons between patients and controls were thresholded using a FDR cluster-level correction approach.

RESULTS

We found no significant differences in functional connectivity between seeds within the default mode, salience, sensorimotor, and language networks and other regions of the brain between patients and controls. However, patients with NDfE had significantly reduced connectivity between intraparietal seeds within the fronto-parietal attention network and predominantly frontal and temporal cortical regions relative to controls; this finding was demonstrated including and excluding the patients with brain lesions. No common alteration in brain structure was observed in patients using voxel-based morphometry. Findings were not influenced by treatment outcome at 1 year.

CONCLUSIONS

Patients with focal epilepsy have brain functional connectivity alterations at diagnosis. Functional brain abnormalities are not necessarily a consequence of the chronicity of epilepsy and are present when seizures first emerge.

Amorphous Copolyesters Containing Monomers Derived from Bisphenols

Amorphous copolyesters based on combinations of ethylene glycol (EG) and 1,4-cyclohexanedimethanol (CHDM) as diols with terephthalic acid have excellent properties, such as toughness, clarity, and chemical resistance and are well known commercial polymers. Several different hydoxyethoxylated bisphenols were copolymerized into the backbone of these amorphous copolyesters in order to raise the glass transition temperature (Tg). The incorporation of bis[4-(2-hydroxyethoxy)phenyl]sulfone (SEO-2) into the amorphous copolyester backbone led to significant Tg increase and improvement in resistance to lipids. Melt viscosity and other mechanical and physical properties were unchanged by the addition of SEO-2.

[High fat diet-induced molecular and physiological dysfunction of the urinary bladder]

BACKGROUND

Obesity with its multiple comorbidities has become a global pandemia. We here report on the pathophysiological aspects of obesity-associated urinary bladder dysfunctions.

MATERIAL AND METHODS

Our results are based on multiple in vitro and in vivo studies including a high fat diet (HFD) rat animal model of which the details are given in the cited publications.

RESULTS

In cultured human detrusor muscle cells, obesity-related pathophysiological mechanisms were directly induced by the saturated free fatty acid palmitate. In HFD animals, we found serious fibrosis of the bladder wall and downregulation of the muscarinic M3-receptor leading to diminished contractility of the urinary bladder. Bariatric surgical intervention (sleeve gastrectomy) reversed the fibrosis.

CONCLUSION

Our results support the relevance of obesity for urological bladder dysfunction. The epidemic dimension of obesity with its steadily growing number of cases requires a re-evaluation of this pathological condition in the urological context.

Metabolically healthy and unhealthy obesity: differential effects on myocardial function according to metabolic syndrome, rather than obesity

BACKGROUND

The term 'metabolically healthy obese (MHO)' is distinguished using body mass index (BMI), yet BMI is a poor index of adiposity. Some epidemiological data suggest that MHO carries a lower risk of cardiovascular disease (CVD) or mortality than being normal weight yet metabolically unhealthy.

OBJECTIVES

We aimed to undertake a detailed phenotyping of individuals with MHO by using imaging techniques to examine ectopic fat (visceral and liver fat deposition) and myocardial function. We hypothesised that metabolically unhealthy individuals (irrespective of BMI) would have adverse levels of ectopic fat and myocardial dysfunction compared with MHO individuals.

SUBJECTS

Individuals were categorised as non-obese or obese (BMI ⩾30 kg m(-2)) and as metabolically healthy or unhealthy according to the presence or absence of metabolic syndrome.

METHODS

Sixty-seven individuals (mean±s.d.: age 49±11 years) underwent measurement of (i) visceral, subcutaneous and liver fat using magnetic resonance imaging and proton magnetic resonance spectroscopy, (ii) components of metabolic syndrome, (iii) cardiorespiratory fitness and (iv) indices of systolic and diastolic function using tissue Doppler echocardiography.

RESULTS

Cardiorespiratory fitness was similar between all groups; abdominal and visceral fat was highest in the obese groups. Compared with age- and BMI-matched metabolically healthy counterparts, the unhealthy (lean or obese) individuals had higher liver fat and decreased early diastolic strain rate, early diastolic tissue velocity and systolic strain indicative of subclinical systolic and diastolic dysfunction. The magnitude of dysfunction correlated with the number of components of metabolic syndrome but not with BMI or with the degree of ectopic (visceral or liver) fat deposition.

CONCLUSIONS

Myocardial dysfunction appears to be related to poor metabolic health rather than simply BMI or fat mass. These data may partly explain the epidemiological evidence on CVD risk relating to the different obesity phenotypes.

Comparative neuropathology of ovine enterotoxemia produced by Clostridium perfringens type D wild-type strain CN1020 and its genetically modified derivatives

Clostridium perfringens type D causes enterotoxemia in sheep and goats. The disease is mediated by epsilon toxin (ETX), which affects the cerebrovascular endothelium, increasing vascular permeability and leading to cerebral edema. In the present study, we compared the distribution and severity of the cerebrovascular changes induced in lambs by C. perfringens type D strain CN1020, its isogenic etx null mutant, and the ETX-producing complemented mutant. We also applied histochemical and immunohistochemical markers to further characterize the brain lesions induced by ETX. Both ETX-producing strains induced extensive cerebrovascular damage that did not differ significantly between each other in nature, neuroanatomic distribution, or severity. By contrast, lambs inoculated with the etx mutant or sterile, nontoxic culture medium did not develop detectable brain lesions, confirming that the neuropathologic effects observed in these infections are dependent on ETX production. Lambs treated with the wild-type and complemented strains showed perivascular and mural vascular edema, as well as serum albumin extravasation, particularly severe in the cerebral white matter, midbrain, medulla oblongata, and cerebellum. Brains of animals inoculated with the ETX-producing strains showed decreased expression of glial fibrillary acidic protein and increased expression of aquaporin-4 in the end-feet processes of the astrocytes around blood vessels. Early axonal injury was demonstrated with anti-amyloid precursor protein immunohistochemistry. Perivascular accumulation of macrophages/microglia with intracytoplasmic albumin globules was also observed in these animals. This study demonstrates that ETX is responsible for the major cerebrovascular changes in C. perfringens type D-induced disease.

Reliability of measurements of tongue and hand strength and endurance using the Iowa Oral Performance Instrument with elderly adults

PURPOSE

This study investigated the reliability of tongue and hand strength and endurance measurements in old adults using the Iowa Oral Performance Instrument (IOPI).

METHOD

Thirty aged-care residents (6 males and 24 females) aged 79-97 years were tested on four occasions two weeks apart to determine test-retest reliability. The primary outcome measures were isometric anterior and posterior tongue and hand strength (best of three trials) and isometric tongue and hand endurance time at 50% of maximal strength.

RESULTS

Changes in the mean between sessions for tongue and hand strength indicated acceptable (< 10%) reliability particularly with familiarisation. The within-subject variation (mean-typical error expressed as a coefficient of variation, CV) indicated higher than acceptable variation for anterior and posterior tongue and hand strength. Intra-class correlations (ICC) indicated moderate to strong reliability for anterior (ICC 0.58-0.77) and posterior (ICC 0.77-0.84) tongue strength and hand strength (ICC 0.79-0.96). No tongue or hand endurance measures were regarded as reliable.

CONCLUSION

These findings indicate that overall tongue and hand strength values demonstrate acceptable reliability in the elderly, especially where familiarisation with the IOPI is provided. Further investigation to reduce sources of variability in tongue endurance measurements is warranted.

Mutational analysis of the tumor-suppressor gene wt1 - detection of a novel homozygous point mutation in sporadic unilateral wilms-tumor

The WT1 gene located on chromosome 11p13, has been identified as the first Wilms' tumor suppressor gene and has been implicated in the development of Wilms' tumor. About 10% of Wilms' tumors analyzed to date carry a mutation and only 6 different point mutations affecting the zinc finger region have been reported. We analyzed the zinc finger coding exons of 38 sporadic Wilms' tumor by SSCP and detected 2 point mutations. One homo/hemizygous mutation, already described in the literature, replaced an arginine in zinc finger II by a stop codon. The other mutation, a replacement of an arginine by a stop codon in zinc finger I, represents a novel mutation.

Canine idiopathic epilepsy: prevalence, risk factors and outcome associated with cluster seizures and status epilepticus

OBJECTIVES

To evaluate the prevalence of cluster seizures and status epilepticus in dogs with idiopathic epilepsy and determine risk factors for cluster seizure frequency, severity and patient outcome.

METHODS

Retrospective review of medical records of 407 dogs with idiopathic epilepsy was made. Follow-up questionnaires were evaluated in cases with cluster seizures.

RESULTS

Mean age at diagnosis of idiopathic epilepsy was 4 years. Cluster seizures were documented in 169 (41%) dogs. German shepherds and boxers were significantly (P=0·04 and 0·01, respectively) more likely to suffer from cluster seizures compared to Labrador retrievers. There was no association between the occurrence of status epilepticus and cluster seizures and frequency and severity of cluster seizures and status epilepticus episodes with age or breed. Intact males were twice as likely (P=0·003) than neutered dogs to suffer from cluster seizures. Intact females had significantly (P=0·007) more frequent cluster seizures than neutered dogs. The median survival time for all dogs with cluster seizures was 95 months. Significantly (P=0·03) more dogs with frequent cluster seizures were euthanased because of the cluster seizures.

CLINICAL SIGNIFICANCE

There was a high prevalence of cluster seizures in dogs with idiopathic epilepsy. Neutering status appears to influence cluster seizure occurrence with intact females more likely to experience more frequent episodes. Euthanasia is associated with frequency of cluster seizure episodes.

ELISPOT assays provide reproducible results among different laboratories for T-cell immune monitoring--even in hands of ELISPOT-inexperienced investigators

Measurements of antibodies in bodily fluids (e.g., by ELISA) have provided robust and reproducible results for decades and such assays have been validated for monitoring of B-cell immunity. In contrast, measuring T-cell immunity has proven to be a challenge due to the need to test live cells in functional assays ex vivo. Several previous efforts looking into the reproducibility of ex vivo T-cell assays between different laboratories, or even within the same laboratory, have provided rather discouraging results. The hypothesis we tested in this study is that those poor results are due to the lack of assay and data analysis standardization, rather than the inherent complexity of T-cell assays. In this study, 11 laboratories across Europe and the United States were provided identical reagents and were asked to follow the same protocol while testing aliquots of the same three cryopreserved peripheral blood mononuclear cells (PBMC) in an interferon-gamma (IFNgamma) ELISPOT assay measuring the antigen-specific T-cell response to a CMV peptide. All individuals performing the assays were ELISPOT novices. At their first attempt, while three of these individuals failed with the basic logistics of the trial, eight detected the peptide-specific CD8+ T-cells in frequencies approximating the values established by the Reference Laboratory. The data show that ELISPOT assays provide reproducible results among different laboratories when the assay procedure and data analysis is standardized. Since ELISPOT assays have been qualified and validated for regulated studies, they are ideal candidates for robust and reproducible monitoring of T-cell activity in vivo.

169. THE MECHANISM OF SPERMATID MATURATION - A LINK TO TUMOUR SUPPRESSION

To comprehensively uncover novel male fertility regulators, we utilised an unbiased forward genetic screen, ENU mutagenesis. Using this approach, we have identified several novel infertile mouse lines including a male-specific infertile line that we designated ‘Joey’. The mutant Joey mice produced no sperm due to an arrest of male germ cells at the round spermatid stage. The mutation was identified in the RNA binding motif 5 (Rbm5) gene that resulted in an arginine to proline substitution within a highly conserved RNA recognition motif of the protein. The substitution of proline is likely to interfere with RNA binding and/or recognition. In humans, the RBM5 gene maps to a region that is frequently deleted in lung cancers. Ex vivo studies have suggested that RBM5 is a tumour suppressor, apoptosis modulator and RNA splicing regulator. To date, the role of Rbm5 has never been liked to male fertility and the Joey line is the only mouse model of Rbm5 dysfunction. Using our RBM5-specific antibody, we showed that RBM5 is expressed in pachytene spermatocytes and round spermatids. Based on the protein localisation, the proposed role of RBM5 in mRNA processing, the onset of the Joey phenotype, and the site of the identified mutation, we hypothesise that the Rbm5 mutant allele results in a hypomorphic protein, and that RBM5 has an essential role in regulating male germ cell mRNA storage, transport and/or translational regulation of mRNAs that are critical for spermatid maturation. Further, we generated mice compound heterozygous of the Joey Rbm5 mutation and Rbm5 null alleles. We showed that the compound heterozygous males are infertile due to spermatid maturation arrest resembling the Joey mutant males. This result further confirmed the identification of the Rbm5 mutation as a cause of infertility in the Joey mice and a crucial role of Rbm5 in male fertility.

104. LRGUK - A NOVEL GENE INVOLVED IN MALE FERTILITY

Infertility affects a large number of Australian men. The causative factor in many of these cases is likely to be genetic in origin. As such, the identification and characterisation of novel genes involved in male fertility represents an important area of research. We have undertaken an N-ethyl-nitrosourea (ENU) mutagenesis screen to identify novel genes involved in male fertility. From this screen we have identified a mouse line that we have designated ‘Kaos’. Male mice that are homozygous for the Kaos mutation are infertile as a result of severely disrupted spermatogenesis, with Kaos homozygote males containing only 20% of the normal number of elongated spermatids in their testes, when examined by nuclear resistance to Triton X-100 solubilisation. In contrast, Kaos homozygote females are fertile. To identify the Kaos causal mutation, we used a combination of DNA linkage analysis and candidate gene sequencing. A point mutation was identified in exon 14 of the Leucine-rich Repeats and Guanylate Kinase domain containing (Lrguk) gene, which introduces a pre-mature stop codon into the Lrguk coding sequence. The function of the LRGUK protein is currently unknown. However preliminary expression and phenotype analysis suggests that Lrguk may have a role in spermiogenesis (i.e. haploid germ cell development). The deduced LRGUK protein contains several potentially important domains including a Guanylate Kinase-like (GK) domain and a number of leucine-rich repeats. The GK-like domain has some homology to guanylate kinase, a metabolic enzyme involved in purine nucleotide metabolism. Studies are currently underway to determine whether the LRGUK protein possesses guanylate kinase enzyme activity. In other proteins, the GK-like domain has evolved into mediating protein-protein interactions (1), and current studies are also aimed at examining this possibility. These studies should provide insight into the function of LRGUK and its role in spermatogenesis. (1) Montgomery J, et al. (2004). MAGUKs in synapse assembly and function: an emerging view. Cell Mol Life Sci. 61(7–8): 911–929.

Association of Ki67 index with prognosis for intermediate-grade canine cutaneous mast cell tumours

Intermediate-grade mast cell tumours (MCT) represent a heterogeneous population of tumours. The prognosis for the majority of dogs is excellent following surgical excision, but a minority die because of their disease. A previous study identified Ki67 expression as a predictor of prognosis in all three grades of MCT. The purpose of this study was to validate those results in a new group of dogs, with intermediate-grade MCT only. Ki67 immunohistochemistry was performed on intermediate-grade MCT from 163 dogs with known outcome. Digital microscopy images were taken from each tumour, and an index calculated of Ki67-positive cells. Ki67 index as a binary variable with a cut-off value of 1.8% was confirmed to be associated with prognosis (hazard ratio = 19.1, P < 0.0001) for this cohort of dogs. The 1-year, 2-year and 3-year survival probabilities (with standard errors) of 127 dogs with a Ki67 index <or=1.8% were [0.95 (0.024), similar for all] and for 36 dogs with a Ki67 index >1.8% were 0.54 (0.100), 0.45 (0.101) and 0.33 (0.104), respectively.

Metabolic profile and nitric oxide synthase expression of skeletal muscle fibers are altered in patients with type 1 diabetes

We investigate muscle fiber composition, fiber-specific glycolytic and oxidative enzyme capacity and nitric oxide synthase (NOS) expression in skeletal muscle of patients with type 1 diabetes (T1D) compared to individuals with normal glucose tolerance (NGT). Vastus lateralis muscle was obtained by percutaneous biopsy from 7 T1D patients and 10 healthy controls with similar characteristics. Using cytophotometry, muscle fiber composition and fiber type-specific glycolytic and oxidative enzyme activities were measured in slow oxidative (SO), fast oxidative glycolytic (FOG) and fast glycolytic (FG) fibers. In addition, NOS 1-3 protein expression was mea-sured. The glycolytic fiber fraction was 1.4 fold higher, whereas FOG and SO fiber fractions were significantly reduced by 13.5% and 6.2% in skeletal muscle from T1D patients. Glycolytic enzyme activities and fiber-specific ratio of glycolytic relative to oxidative enzyme activity were significantly higher in all fiber types of T1D patients and correlated with HbA (1c). Expression of NOS1-3 isoforms was reduced in skeletal muscle of T1D subjects. Increased glycolytic enzyme activity in muscle of T1D patients is most likely due to both a higher number of fast glycolytic fibers and a shift towards increased glycolytic metabolism in all fiber types. Alterations in muscle fiber distribution and enzyme activities seem to be due to impaired long-term glycemic control.

Congenital hyposomatotropism in a domestic shorthair cat presenting with congenital corneal oedema

A six-month-old, female, domestic shorthair cat was presented with a history of failure to grow and bilateral corneal opacity caused by corneal oedema. Congenital hyposomatotropism and possible secondary hypothyroidism were diagnosed on the basis of fasting serum levels of insulin-like growth factor-1 and thyroxine levels, respectively. These endocrinopathies are rare in the cat and have not been reported to cause ocular signs. The cat died during investigation of these diseases, and histopathological examination of the eyes showed significantly reduced corneal endothelial cell density and number of corneal epithelial cell layers when compared with age-matched healthy control corneas. These changes were implicated in the development of the corneal oedema.