Catherine E. Huggins

The intrinsic resistance of female hearts to an ischemic insult is abrogated in primary cardiac hypertrophy.

Important sex differences in cardiovascular disease outcomes exist, including conditions of hypertrophic cardiomyopathy and cardiac ischemia. Studies of sex differences in the extent to which load-independent (primary) hypertrophy modulates the response to ischemia-reperfusion (I/R) damage have not been characterized. We have previously described a model of primary genetic cardiac hypertrophy, the hypertrophic heart rat (HHR). In this study the sex differences in HHR cardiac function and responses to I/R [compared to control normal heart rat (NHR)] were investigated ex vivo. The ventricular weight index was markedly increased in HHR female (7.82 +/- 0.49 vs. 4.80 +/- 0.10 mg/g; P < 0.05) and male (5.76 +/- 0.22 vs. 4.62 +/- 0.07 mg/g; P < 0.05) hearts. Female hearts of both strains exhibited a reduced basal contractility compared with strain-matched males [maximum first derivative of pressure (dP/dt(max)): NHR, 4,036 +/- 171 vs. 4,258 +/- 152 mmHg/s; and HHR, 3,974 +/- 160 vs. 4,540 +/- 259 mmHg/s; P < 0.05]. HHR hearts were more susceptible to I/R (I = 25 min, and R = 30 min) injury than NHR hearts (decreased functional recovery, and increased lactate dehydrogenase efflux). Female NHR hearts exhibited a significantly greater recovery (dP/dt(max)) post-I/R relative to male NHR (95.0 +/- 12.2% vs. 60.5 +/- 9.4%), a resistance to postischemic dysfunction not evident in female HHR (29.0 +/- 5.6% vs. 25.9 +/- 6.3%). Ventricular fibrillation was suppressed, and expression levels of Akt and ERK1/2 were selectively elevated in female NHR hearts. Thus the occurrence of load-independent primary cardiac hypertrophy undermines the intrinsic resistance of female hearts to I/R insult, with the observed abrogation of endogenous cardioprotective signaling pathways consistent with a potential mechanistic role in this loss of protection.

Elevated intracardiac angiotensin II leads to cardiac hypertrophy and mechanical dysfunction in normotensive mice

Introduction Angiotensin II (Ang II) is known to induce cardiac growth and modulate myocardial contractility. It has been reported that elevated levels of endogenous Ang II contribute to the development of cardiac hypertrophy in hypertensives. However, the long-term functional effects of cardiac exposure to Ang II in normotensives is unclear. A recently developed transgenic mouse (TG1306/1R), in which cardiac-specific overproduction of Ang II produces primary hypertrophy, provides a new experimental model for investigation of this phenotype. The aim of the present study was to use this model to investigate whether there is a functional deficit in primary hypertrophy that may predispose to cardiac failure and sudden death. We hypothesised that primary cardiac hypertrophy is associated with mechanical dysfunction in the basal state. Methods Normotensive heterozygous TG1306/1R mice harbouring multiple copies of a cardiac-specific rat angiotensinogen gene were studied at age 30—40 weeks and compared with age-matched wild-type littermates. Left ventricular function was measured ex vivo in bicarbonate buffer-perfused, Langendorffmounted hearts ( at a perfusion pressure of 80 mmHg, 37°C) using a fluid-filled PVC balloon interfaced to a pressure transducer and digital data acquisition system. Results There was no difference in the mean (±SEM) intrinsic heart rate of TG1306/1R and wild-type control mice (357.4±11.8 vs. 367.5±20.9 bpm, n=9 & 7). Under standardised end-diastolic pressure conditions, TG1306/1R hearts exhibited a significant reduction in peak developed pressure (132.2±9.4 vs. 161.5±3.1 mmHg, n=9 & 7, p<0.05) and maximum rate of pressure development (3566.7±323.7 vs. 4486.3±109.4 mmHg, n=9 & 7, p<0.05). TG1306/1R mice show a significant correlation between incidence of arrhythmia and increasing heart size (Spearmans correlation coefficient 0.61). Conclusion These data demonstrate that chronic in vivo exposure to elevated levels of intra-cardiac Ang II is associated with significant contractile abnormalities evident in the ex vivo intact heart. Our findings suggest that endogenous overproduction of cardiac Ang II, independent of changes in blood pressure, is sufficient to induce ventricular remodelling that culminates in impaired cardiac function which may precede failure.

Effect of increasing dietary calcium through supplements and dairy food on body weight and body composition: a meta-analysis of randomised controlled trials.

This meta-analysis of randomised controlled trials assessed the effect of Ca on body weight and body composition through supplementation or increasing dairy food intake. Forty-one studies met the inclusion criteria (including fifty-one trial arms; thirty-one with dairy foods (n 2091), twenty with Ca supplements (n 2711). Ca intake was approximately 900 mg/d higher in the supplement groups compared with control. In the dairy group, Ca intake was approximately 1300 mg/d. Ca supplementation did not significantly affect body weight (mean change ( - 0·17, 95% CI - 0·70, 0·37) kg) or body fat (mean change ( - 0·19, 95% CI - 0·51, 0·13) kg) compared to control. Similarly, increased dairy food intake did not affect body weight ( - 0·06, 95% CI - 0·54, 0·43) kg or body fat change ( - 0·36, 95% CI - 0·80, 0·09) kg compared to control. Sub-analyses revealed that dairy supplementation resulted in no change in body weight (nineteen studies, n 1010) ( - 0·32, 95% CI - 0·93, 0·30 kg, P= 0·31), but a greater reduction in body fat (thirteen studies, n 564) ( - 0·96, 95% CI - 1·46, - 0·46 kg, P < 0·001) in the presence of energy restriction over a mean of 4 months compared to control. Increasing dietary Ca intake by 900 mg/d as supplements or increasing dairy intake to approximately 3 servings daily (approximately 1300 mg of Ca/d) is not an effective weight reduction strategy in adults. There is, however, an indication that approximately 3 servings of dairy may facilitate fat loss on weight reduction diets in the short term.

Influence of dietary modifications on the blood pressure response to antihypertensive medication

Identifying dietary modifications that potentiate the blood pressure (BP)-lowering effects of antihypertensive medications and that are practical for free-living people may assist in achieving BP reduction goals. We assessed whether two dietary patterns were effective in lowering BP in persons on antihypertensive therapy and in those not on therapy. Ninety-four participants (38/56 females/males), aged 55·6 (SD 9·9) years, consumed two 4-week dietary regimens in random order (Dietary Approaches to Stop Hypertension (DASH)-type diet and low- Na high-K (LNAHK) diet) with a control diet before each phase. Seated home BP was measured daily for the last 2 weeks in each phase. Participants were grouped based on antihypertensive drug therapy. The LNAHK diet produced a greater fall in systolic BP (SBP) in those on antihypertensive therapy (-6·2 (SD 6·0) mmHg) than in those not on antihypertensive therapy (-2·8 (SD 4·0) mmHg) (P = 0·036), and this was greatest for those on renin-angiotensin system (RAS) blocker therapy (-9·5 (SD 6·4) mmHg) (interaction P = 0·007). The fall in SBP on the DASH-type diet, in those on therapy (overall -1·1 (SD 6·2) mmHg; renin-angiotensin blocker therapy -4·2 (SD 4·7) mmHg), was not as marked as that observed on the LNAHK diet. Dietary modifications are an important part of all hypertension management regimens, and a low-Na and high-K diet enhances the BP-lowering effect of antihypertensive medications, particularly those targeting the RAS.

Energy intake of shift workers compared to fixed day workers: A systematic review and meta-analysis.

ABSTRACT Shift work is an established risk factor for a number of chronic conditions associated with excess energy intake including obesity, cardiovascular disease and type 2 diabetes. This systematic review investigated whether the 24 h energy intake of shift workers differs to that of fixed day workers. Included articles compared energy intake of shift workers (shift included midnight) with fixed day workers. There were 10 367 day workers and 4726 shift workers from 12 studies included in the qualitative analysis and meta-analyses. The standardised mean difference (95% CI) in energy intake between shift and day workers was −0.04 (−0.11, 0.03); I2 = 54%. Qualitative results on macronutrient intakes were conflicting. Reported energy intakes were not different between day workers and shift workers, suggesting that other factors such as circadian misalignment, meal timing, food choice and diurnal variation of energy metabolism at night may be responsible for the increased rates of obesity observed in shift workers. Guidance on health and well-being is required for this at-risk population group.

How does nutritional state change during a subacute admission? Findings and implications for practice.

Background/Objectives:Nutritional status influences patients’ clinical and functional outcomes. The aims were to identify changes in nutritional state during subacute care and associated participant characteristics.Subjects/Methods:A longitudinal study was undertaken with consecutive patients admitted to subacute care wards during a 3-month period. Participants were recruited under a waiver of consent to reflect the usual demographic. Change in classification (malnourished, at risk of malnutrition, well nourished) of the full Mini Nutritional Assessment (full MNA) between admission and discharge was the primary outcome. Weight (kg), mid-arm and calf circumference (cm) change were secondary outcomes. Hand grip strength (kg) and fat-free mass (kg) (assessed using bioelectrical impedance analysis) were measured for a consenting subgroup.Results:Participants (n=248, 36.7% male) had a median age of 80 years and a length of stay of 17 days. On admission, 29.1% were classified as malnourished. By discharge, nutritional classification remained stable for 62.0% of participants (n=132), declined for 10.3% (n=22) and improved for 27.7% (n=59, including 52.5% malnourished on admission). Impaired cognition (odds ratio (OR)=0.169, P=0.002) and higher full MNA score at admission (OR=0.870, P=0.001) reduced odds of improvement in full MNA. There was no change in hand grip strength (n=46), but there was a decline in mean fat-free mass (−1.1 kg, 95% confidence interval: −0.1 to −2.2 kg, P=0.043, n=24).Conclusions:Multidisciplinary care supports the nutritional state of most patients admitted to subacute care. Those with cognitive impairments or at risk of malnutrition were less likely to demonstrate improvement and may benefit from more intensive or tailored nutritional care.

Peritoneal dialysis patients have higher prevalence of gastrointestinal symptoms than hemodialysis patients

OBJECTIVE Malnutrition is common in dialysis patients and is attributed to decreased food intake, and/or chronic systemic inflammation linked to dialysis-related comorbidities and complications. This study aimed to determine the prevalence of gastrointestinal (GI) symptoms in dialysis patients and whether this impacts food intake. DESIGN Cross-sectional study. SETTING Tertiary teaching hospital. PARTICIPANTS All consenting hospital peritoneal dialysis (PD) and hemodialysis (HD) patients. METHODS Patients were interviewed by a dietitian regarding the prevalence and impact of GI symptoms (nausea, vomiting, bloating, early satiety, diarrhea, heartburn, fatigue, and weight changes). Serum levels of albumin were measured, and the use of medication known to cause GI symptoms was recorded. MAIN OUTCOME MEASURE Presence of GI symptoms. RESULTS The PD (n = 122) and HD (n = 172) groups were similar in age, gender, and presence of diabetes. Serum albumin levels were lower for those on PD compared with HD (3.2 vs. 3.5 g/dL, P < .001). Eighty-five percent of the patients on PD reported at least 1 GI symptom, compared with 51% on HD. Compared with HD, more PD patients reported that GI symptoms were related to the onset of dialysis (55% vs. 12%, P < .001). A greater number of PD patients (compared with HD patients) reported a decrease in food intake (53% vs. 14%, P < .001) and that they had attempted dietary changes to alleviate symptoms (34% vs. 9%, P < .001). CONCLUSION These results should influence dietetic educational practice. In addition to the provision of adequate protein and energy, dialysis patients should be counselled regarding the management of GI symptoms and monitored for the prevalence and severity of these symptoms.

Dietary fish oil is antihypertrophic but does not enhance postischemic myocardial function in female mice

Clinically and experimentally, a case for omega-3 polyunsaturated fatty acid (PUFA) cardioprotection in females has not been clearly established. The goal of this study was to investigate whether dietary omega-3 PUFA supplementation could provide ischemic protection in female mice with an underlying genetic predisposition to cardiac hypertrophy. Mature female transgenic mice (TG) with cardiac-specific overexpression of angiotensinogen that develop normotensive cardiac hypertrophy and littermate wild-type (WT) mice were fed a fish oil-derived diet (FO) or PUFA-matched control diet (CTR) for 4 wk. Myocardial membrane lipids, ex vivo cardiac performance (intraventricular balloon) after global no-flow ischemia and reperfusion (15/30 min), and reperfusion arrhythmia incidence were assessed. FO diet suppressed cardiac growth by 5% and 10% in WT and TG, respectively (P < 0.001). The extent of mechanical recovery [rate-pressure product (RPP) = beats/min x mmHg] of FO-fed WT and TG hearts was similar (50 +/- 7% vs. 45 +/- 12%, 30 min reperfusion), and this was not significantly different from CTR-fed WT or TG. To evaluate whether systemic estrogen was masking a protective effect of the FO diet, the responses of ovariectomized (OVX) WT and TG mice to FO dietary intervention were assessed. The extent of mechanical recovery of FO-fed OVX WT and TG (RPP, 50 +/- 4% vs. 64 +/- 8%) was not enhanced compared with CTR-fed mice (RPP, 60 +/- 11% vs. 80 +/- 8%, P = 0.335). Dietary FO did not suppress the incidence of reperfusion arrhythmias in WT or TG hearts (ovary-intact mice or OVX). Our findings indicate a lack of cardioprotective effect of dietary FO in females, determined by assessment of mechanical and arrhythmic activity postischemia in a murine ex vivo heart model.

Insulin pump therapy in children and adolescents: Changes in dietary habits, composition and quality of life

Continuous subcutaneous insulin infusion (CSII) can improve glycaemic control and dietary flexibility compared with conventional insulin therapies. There is little information on whether users are utilising this increased dietary flexibility, and whether dietary quality is affected.

Iodine status in Melbourne adults in the early 1990s and 2007–08

Objective: To investigate the iodine status of Melbourne adults in 1992–94 and 2007–08, and to assess dietary iodine intake to enable comparison with recommended Nutrient Reference Values.