Consumer trust in the dairy value chain in China: The role of trustworthiness, the melamine scandal, and the media.

This study provides a deep insight into Chinese consumer trust in the Chinese dairy value chain, as a lack of trust due to the 2008 melamine scandal has been widely recognized as a barrier to the development of the domestic dairy industry in China. Based on face-to-face interviews with 954 Chinese consumers in Beijing, Shanghai, and Shijiazhuang, this study measured consumer trust in farmers, manufacturers, retailers, the government, and third parties. Consumer trust was studied by measuring the effect of beliefs on the trustworthiness of actors (i.e., competence, benevolence, integrity, credibility, and openness), and current experiences regarding the melamine scandal and the media. The results showed that the level of trust in dairy chain actors varied. The government and third parties were relatively highly trusted, whereas retailers were considered less trustworthy. The importance of consumer beliefs about trustworthiness are different among actors. Consumer belief of competence determines trust in farmers and manufacturers. For retailers, the government, and third parties, respectively, benevolence, credibility, and openness are the most important factors. Trust in dairy chain actors is still strongly negatively affected by current experiences regarding the melamine scandal, even though it occurred more than 10 years ago. Using social media to directly provide more information and establish continuous daily communication with consumers could help manufacturers and third parties to strengthen consumer trust.

Effects of aerobic or resistance exercise training on cardiovascular autonomic function of subjects with type 2 diabetes: A pilot study.

BACKGROUND AND AIMS: Both aerobic (AER) and resistance (RES) training improve metabolic control in patients with type 2 diabetes (T2DM). However, information on the effects of these training modalities on cardiovascular autonomic control is limited. Our aim was to compare the effects of AER and RES training on cardiovascular autonomic function in these subjects. METHODS AND RESULTS: Cardiovascular autonomic control was assessed by Power Spectral Analysis (PSA) of Heart Rate Variability (HRV) and baroreceptors function indexes in 30 subjects with T2DM, randomly assigned to aerobic or resistance training for 4 months. In particular, PSA of HRV measured the Low Frequency (LF) and High Frequency (HF) bands of RR variations, expression of prevalent sympathetic and parasympathetic drive, respectively. Furthermore, we measured the correlation occurring between systolic blood pressure and heart rate during a standardized Valsalva maneuver using two indexes, b2 and b4, considered an expression of baroreceptor sensitivity and peripheral vasoactive adaptations during predominant sympathetic and parasympathetic drive, respectively. After training, the LF/HF ratio, which summarizes the sympatho-vagal balance in HRV control, was similarly decreased in the AER and RES groups. After AER, b2 and b4 significantly improved. After RES, changes of b2 were of borderline significance, whereas changes of b4 did not reach statistical significance. However, comparison of changes in baroreceptor sensitivity indexes between groups did not show statistically significant differences. CONCLUSION: Both aerobic and resistance training improve several indices of the autonomic control of the cardiovascular system in patients with T2DM. Although these improvements seem to occur to a similar extent in both training modalities, some differences cannot be ruled out. CLINICAL TRIAL REGISTRATION NUMBER: NCT01182948, clinicaltrials.gov.

Effect of moderate aerobic exercise on sympatho-vagal balance in Type 2 diabetic patients.

AIMS: The purpose of the study was to determine long-term cardiovascular autonomic adaptation to moderate endurance aerobic exercise in people with Type 2 diabetes in order to test the hypothesis of an enhanced vagal drive. METHODS: We analysed the power spectral density of heart rate cyclic variations at rest, while lying, and while standing in 12 sedentary, non-smoking, Type 2 diabetic individuals. Testing was performed before and after a 6-month, supervised, progressive, aerobic training programme, twice weekly. Heart rate variability was assessed by autoregressive power spectral analysis (PSA); this method allows reliable quantification of low-frequency (LF) and high-frequency (HF) components, which are considered to be under mainly sympathetic and purely parasympathetic control, respectively. RESULTS: In 10-min electrocardiogram recordings, mean RR intervals values lying and standing were similar before and after physical exercise. Likewise, total heart rate variability, expressed as total power spectral density (PSD), was not altered by exercise. In contrast, on standing, the HF component, expressed in normalized units, was significantly higher (20.1 +/- 4 vs. 30.4 +/- 5, P < 0.01), whereas the LF component was significantly lower (68.1 +/- 7 vs. 49.8 +/- 8, P < 0.01) after exercise; hence, on standing, the LF/HF ratio, reflecting the sympathetic vs. parasympathetic balance, was markedly lower (16.2 +/- 11 vs. 5.2 +/- 3.2, P = 0.003). No significant exercise-related changes in these PSA components were observed on lying. CONCLUSIONS: A twice-weekly, 6-month, moderate, aerobic exercise programme, without a concomitant weight loss diet, is associated with significant improvements in cardiovascular autonomic function in overweight, non-smoking, Type 2 diabetic individuals.

Power spectral analysis of heart rate in hypothyroidism.

OBJECTIVE: The aim of the present study was to evaluate the impact of hypothyroidism on the autonomic regulation of the cardiovascular system by analysing separately sympathetic and parasympathetic influences on the heart. DESIGN: In seven newly diagnosed untreated hypothyroid patients we analysed power spectral density of heart rate cyclic variations at rest, while lying, and while standing. The same protocol was repeated after the induction of stable euthyroidism by levothyroxine (L-T(4)) treatment. The results were also compared with those obtained from seven age-, sex- and body mass index-matched control subjects. METHODS: Heart rate variability was evaluated by autoregressive power spectral analysis (PSA). This method allows reliable quantification of low frequency (LF) and high frequency (HF) components of the heart rate power spectral density. These are considered to be under mainly sympathetic and purely parasympathetic control respectively. In addition, heart rate variations during deep breathing, lying to standing, and Valsalva's manoeuvre were assessed. RESULTS: PSA showed a sharp reduction in the HF (parasympathetic) component in hypothyroid subjects compared with controls (lying, 29.4+/-5.4 vs 47.7+/-6.3 normalized units (NU) (means +/- s.e.m.), P<0.05; standing, 14.0+/-3.5 vs 32.1+/-3.6NU, P<0.005). Conversely, the LF (mainly sympathetic) component was higher in hypothyroid subjects than in controls (lying, 61.6+/-6.4 vs 45.4+/-6.7 NU; standing, 71.7+/-8.0 vs 53.1+/-5.6NU), this difference being significant in the standing position. Hence, the LF/HF ratio, which is considered an index of sympathovagal balance, was increased in hypothyroid subjects while both lying (2.75+/-0.6 vs 1.16+/-0.3; P<0.05) and standing (10.0+/-3.7 vs 1.85+/-0.3; P<0. 02). Total heart rate variability, expressed as total power spectral density, was lower in hypothyroid patients than in control subjects, this difference being significant in the lying position (574+/-126 vs 2302+/-994ms(2), P<0.05). In patients re-examined after L-T(4) therapy, complete normalization of cardiovascular parameters was observed (LF/HF ratio, lying, 1.26+/-0.4; standing, 2.56+/-0.8, both P<0.01 vs baseline values). The response to conventional cardiovascular autonomic tests was not significantly different between hypothyroid patients and healthy controls, and did not change in patients after therapy. CONCLUSIONS: These results suggest that, contrary to the clinical picture, thyroid hormone deficiency is associated with an increased sympathetic influence on the autonomic cardiovascular system. The changes in sympathetic function could be explained by a secondary adaptation to an altered cardiovascular responsiveness.

Comparative assessment of peripheral sympathetic function by postural vasoconstriction arteriolar reflex and sympathetic skin response in NIDDM patients.

PURPOSE: The aim of the study was to compare peripheral sympathetic adrenergic and cholinergic nerve function in NIDDM (non-insulin-dependent diabetes mellitus) patients with various degrees of diabetic neuropathy and neuropathic foot ulceration. The parameters used were postural vasoconstriction arteriolar reflex (VAR) and sympathetic skin response (SSR), respectively. PATIENTS AND METHODS: Forty-seven NIDDM patients were studied. No patients had clinically significant peripheral vascular disease. They were divided according to peripheral somatic neuropathy, assessed by clinical score and vibration perception threshold (VPT). Twenty-two patients showed no significant evidence of peripheral neuropathy and normal VPT (DN-); 15 had signs and symptoms of neuropathy and VPT alteration (DN+); 10 had diabetic neuropathy and foot ulceration (DNU). Twenty-two normal subjects were also examined as a control group. Resting arteriovenous shunt skin blood flow, measured using laser-Doppler flowmetry, and the VAR of the big toe on lowering the foot were studied. Sympathetic skin response was assessed by an EMG apparatus. Autonomic function was also investigated by using standard cardiovascular reflex tests. RESULTS: Resting blood flow values were similar in the three NIDDM groups and in the control group. VAR to foot lowering was significantly impaired in all NIDDM groups by comparison with controls (72.8 +/- 2.1%, mean +/- SEM), this impairment being progressively more pronounced in DN- (58.8 +/- 2.3%, P < 0.001), DN+ (33.3 +/- 3.0%, P < 0.001 versus DN-) and DNU (8.6 +/- 2.7%, P < 0.001 versus DN+). Sympathetic skin response was assessed in 28 patients and was significantly impaired in DN-compared with the control group (2.53 +/- 0.04 versus 2.71 +/- 0.04 log mcV, P < 0.01). This impairment was severe in the DNU compared with the DN+ group (1.36 +/- 0.05 versus 2.26 +/- 0.04 log mcV, P < 0.005). A positive correlation was found between VAR values and SSR (P < 0.001), and these measurements were also closely correlated with several parameters of central autonomic and somatic neuropathy. CONCLUSION: These results indicate that peripheral sympathetic adrenergic and cholinergic fibers simultaneously undergo early alterations in diabetic patients, even when there is no clinical neuropathy. Our data also show almost complete abolition of peripheral sympathetic activity in NIDDM patients with foot ulceration.

Acute effect of insulin on autonomic regulation of the cardiovascular system: a study by heart rate spectral analysis.

Insulin is suggested to have direct effects on the cardiovascular system but these are not well described. We assessed the possible influence of insulin on autonomic control of heart function. A 2-h hyperinsulinaemic euglycaemic clamp was performed in 10 healthy women (mean age 21.7 +/- 1.3 years), at two different insulin infusion rates: 80 mU m-2 and 400 mU m-2 min-1, in 7 and 3 subjects, respectively. Saline alone was infused in 4 controls. Power spectral analysis (PSA) of heart rate was recorded before and after 90-120 min of insulin infusion, as were blood pressure and heart rate. Although there were no significant changes in heart rate or blood pressure, PSA showed marked reductions of high frequency (HF) bands after insulin (2.60 +/- 0.12 vs 2.09 +/- 0.16 log ms2, p < 0.005), as at both low and high infusion rates (2.46 +/- 0.13 to 2.14 +/- 0.23 log ms2, p < 0.05, and 2.92 +/- 0.18 to 1.98 +/- 0.06 log ms2, p < 0.01, respectively). There were no significant changes of low frequency (LF) bands. Densities at LF and HF did not change significantly in control studies. As HF and LF are considered to reflect parasympathetic and mainly sympathetic control respectively, our observation of an increased LF/HF ratio (0.13 +/- 0.10 vs 0.63 +/- 0.13, p < 0.005) may be considered an index of relative sympathetic predominance induced by insulin infusion. We conclude that insulin affects the cardiovascular system, reducing vagal influence on the heart and inducing a relative hypersympathetic tone.

Power spectral analysis of heart rate in hyperthyroidism.

The aim of the present study was to evaluate the impact of hyperthyroidism on the cardiovascular system by separately analyzing the sympathetic and parasympathetic influences on heart rate. Heart rate variability was evaluated by autoregressive power spectral analysis. This method allows a reliable quantification of the low frequency (LF) and high frequency (HF) components of the heart rate power spectral density; these are considered to be under mainly sympathetic and pure parasympathetic control, respectively. In 10 newly diagnosed untreated hyperthyroid patients with Graves' disease, we analyzed power spectral density of heart rate cyclic variations at rest, while lying, and while standing. In addition, heart rate variations during deep breathing, lying and standing, and Valsalva's maneuver were analyzed. The results were compared to those obtained from 10 age-, sex-, and body mass index-matched control subjects. In 8 hyperthyroid patients, the same evaluation was repeated after the induction of stable euthyroidism by methimazole. Heart rate power spectral analysis showed a sharp reduction of HF components in hyperthyroid subjects compared to controls [lying, 13.3 +/- 4.1 vs. 32.0 +/- 5.6 normalized units (NU; P < 0.01); standing, 6.0 +/- 2.7 vs. 15.0 +/- 4.0 NU (P < 0.01); mean +/- SEM]. On the other hand components were comparable in the 2 groups (lying, 64.0 +/- 6.9 vs. 62.0 +/- 6.5 NU; standing, 77.0 +/- 6.5 vs. 78.0 +/- 5.4 NU). Hence, the LF/HF ratio, which is considered an index of sympathovagal balance, was increased in hyperthyroid subjects while both lying (11.3 +/- 4.5 vs. 3.5 +/- 1.1; P < 0.05) and standing (54.0 +/- 12.6 vs. 9.8 +/- 2.6; P < 0.02). This parameter was positively correlated with both T3 (r = 0.61; P < 0.05) and free T4 (r = 0.63; P < 0.05) serum levels. Among traditional cardiovascular autonomic tests, the reflex response of heart rate during lying to standing was significantly lower in hyperthyroid patients than in controls (1.12 +/- 0.03 vs. 1.31 +/- 0.04; P < 0.002). No statistically significant difference in reflex responses between the two groups was found in deep breathing or Valsalva's maneuver. In the 8 patients reexamined after methimazole treatment, we observed complete normalization of altered cardiovascular parameters, with slight predominance of the vagal component compared with controls. These results suggest that thyroid hormone excess may determine reduced parasympathetic activity and, thus, a relative hypersympathetic tone.

The Verona diabetes study: a population-based survey on known diabetes mellitus prevalence and 5-year all-cause mortality.

This population-based survey aimed to determine the prevalence of known diabetes mellitus on 31 December 1986, and to assess all-cause mortality in the subsequent 5 years (1987-1991) in Verona, Italy. In the study of prevalence, 5996 patients were identified by three independent sources: family physicians, diabetes clinics, and drug prescriptions for diabetes. Mortality was assessed by matching all death certificates of Verona in 1987-1991 with the diabetic cohort. Overall diabetes prevalence was 2.61% (95% confidence interval 2.56-2.67). Prevalence of insulin-dependent and non-insulin-dependent diabetes mellitus was 0.069% (0.059-0.078) and 2.49% (2.43-2.54), respectively. Diabetes prevalence sharply increased after age 35 years up to age 75-79, and finally declined. Prevalence was higher in men up to age 69 years, in women after age 75 years. Of the diabetic cohort 1260 patients (592 men, 668 women) died by 31 December 1991, yielding an overall standardized mortality ratio of 1.46 (CI 1.38-1.54). Even though the differences narrowed with age, mortality rates in the diabetic cohort were higher than in the non-diabetic population at all ages. Women aged 65-74 years showed observed/expected ratio higher than men (2.27, CI 1.92-2.66, vs 1.50, CI 1.30-1.72), while in other age groups the sex-related differences were not significant. Pharmacological treatment of diabetes was associated with an excess mortality, while treatment with diet alone showed an apparent protective effect on mortality (observed/expected ratio 0.73, CI 0.58-0.92).(ABSTRACT TRUNCATED AT 250 WORDS)