Calf Blood Research Articles

Statistical validation of wavelet transform coherence method to assess the transfer of calf muscle activation to blood pressure during quiet standing.

BackgroundContinuous and discrete wavelet transforms have been established as valid tools to analyze non-stationary and transient signals over Fourier domain methods. Additionally, Fourier transform based coherence methods provide aggregate results but do not provide insights into the changes in coherent behavior over time, hence limiting their utility.MethodsStatistical validation of the wavelet transform coherence (WTC) was conducted with simulated data sets. Time frequency maps of signal coherence between calf muscle electromyography (EMG) and blood pressure (BP) were obtained by WTC to provide further insight into their interdependent time-varying behavior via the skeletal muscle pump during quiet stance. Data were collected from healthy young males (n = 5, 19–28 years) during a quiet stance on a balance platform. Waveforms for EMG and BP were acquired and processed for further analysis.ResultsLow values of bias and standard deviation (< 0.1) were observed and the use of both simulated and real data demonstrated that the WTC method was able to identify time points of significant coherence (> Threshold) and objectively detect existence of interdependent activity between the calf muscle EMG and blood pressure.ConclusionsThe WTC method effectively identified the presence of linear coupling between the EMG and BP signals during quiet standing. Future studies with more human data are needed to establish the exact characteristics of the identified relationship.

Exercise training improves endothelial function in resistance arteries of young prehypertensives

Prehypertension is associated with reduced conduit artery endothelial function and perturbation of oxidant/antioxidant status. It is unknown if endothelial dysfunction persists to resistance arteries and if exercise training effects oxidant/antioxidant balance in young prehypertensives. We examined resistance artery function using venous occlusion plethysmography measurement of forearm (FBF) and calf blood flow (CBF) at rest and during reactive hyperemia, as well as lipid peroxidation (8-iso-PGF2α) and antioxidant capacity (Trolox-equivalent antioxidant capacity; TEAC) before and after exercise intervention or time-control. Forty-three unmedicated prehypertensive and fifteen matched normotensive time-controls met screening requirements and participated in the study (age: 21.1±0.8 years). Prehypertensive subjects were randomly assigned to resistance exercise training (PHRT; n=15), endurance exercise training (PHET; n=13) or time-control groups (PHTC; n=15). Treatment groups exercised 3 days per week for 8 weeks. Peak and total FBF were lower in prehypertensives than normotensives (12.7±1.2 ml/min/100ml tissue and 89.1±7.7 ml/min/100ml tissue vs. 16.3±1.0 ml/min/100ml tissue and 123.3±6.4 ml/min/100ml tissue, respectively; p<0.05). Peak and total CBF were lower in prehypertensives than normotensives (15.3±1.2 ml/min/100ml tissue and 74±8.3 ml/min/100ml tissue vs. 20.9±1.4 ml/min/100ml tissue and 107±9.2 ml/min/100ml tissue, respectively; p<0.05). PHRT and PHET improved humoral measures of Trolox-equivalent antioxidant-capacity (TEAC) (+24% and +30%) and 8-iso-PGF2α (−43% and −40%, respectively; p<0.05). This study provides evidence that young prehypertensives exhibit reduced resistance artery endothelial function and that short term (8weeks) resistance or endurance training are effective in improving resistance artery endothelial function and oxidant/antioxidant balance in young prehypertensives.

A double-blind placebo-controlled cross-over study of the vascular effects of midodrine in neuropathic compared with hyperadrenergic postural tachycardia syndrome

POTS (postural tachycardia syndrome) is a chronic form of OI (orthostatic intolerance). Neuropathic POTS is characterized by decreased adrenergic vasoconstriction, whereas hyperadrenergic POTS exhibits increased adrenergic vasoconstriction. We hypothesized that midodrine, an α1-adrenergic receptor agonist, would increase CVR (calf vascular resistance), decrease C(v) (calf venous capacitance) and decrease orthostatic tachycardia in neuropathic POTS, but not alter haemodynamics in hyperadrenergic POTS. A total of 20 POTS patients (12 neuropathic and eight hyperadrenergic), ages 12-20 years, participated in this randomized placebo-controlled double-blind cross-over study. Of these subjects, 15 were female. POTS subjects received 2 weeks of treatment with midodrine or placebo, with increased dosing from 2.5 to 10 mg three times daily. Following a 7-day drug-washout period, subjects received the cross-over treatment. HR (heart rate), MAP (mean arterial pressure), Q(calf) (calf blood flow) and CVR were measured supine and during 35° HUT (head-up tilt). C(v) was measured supine. In neuropathic POTS, midodrine decreased supine HR, Q(calf) and C(v), while increasing MAP and CVR compared with placebo. During HUT, in neuropathic POTS, midodrine decreased HR, Q(calf) and C(v), while increasing MAP and CVR. In hyperadrenergic POTS, placebo and midodrine both decreased upright HR and increased supine CVR. Placebo also increased supine C(v), compared with midodrine in hyperadrenergic POTS. Therefore midodrine improved postural tachycardia in neuropathic POTS by increasing CVR and decreasing Q(calf) and C(v), whereas these effects were not seen in hyperadrenergic POTS patients who experienced a placebo effect. This suggests that midodrine is probably an effective treatment for neuropathic POTS, but not for hyperadrenergic POTS.

Beta blockers for peripheral arterial disease

Beta (β) blockers are indicated for use in coronary artery disease (CAD). However, optimal therapy for people with CAD accompanied by intermittent claudication has been controversial because of the presumed peripheral haemodynamic consequences of beta blockers, leading to worsening symptoms of intermittent claudication. This is an update of a review first published in 2008. To quantify the potential harmful effects of beta blockers on maximum walking distance, claudication distance, calf blood flow, calf vascular resistance and skin temperature when used in patients with peripheral arterial disease (PAD). For this update, the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched March 2013) and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2013, Issue 2). Randomised controlled trials (RCTs) evaluating the role of both selective (β1) and non-selective (β1 and β2) beta blockers compared with placebo. We excluded trials that compared different types of beta blockers. Primary outcome measures were claudication distance in metres, time to claudication in minutes and maximum walking distance in metres and minutes (as assessed by treadmill).Secondary outcome measures included calf blood flow (mL/100 mL/min), calf vascular resistance and skin temperature (ºC). We included six RCTs that fulfilled the above criteria, with a total of 119 participants. The beta blockers studied were atenolol, propranolol, pindolol and metoprolol. All trials were of poor quality with the drugs administered over a short time (10 days to two months). None of the primary outcomes were reported by more than one study. Similarly, secondary outcome measures, with the exception of vascular resistance (as reported by three studies), were reported, each by only one study. Pooling of such results was deemed inappropriate. None of the trials showed a statistically significant worsening effect of beta blockers on time to claudication, claudication distance and maximal walking distance as measured on a treadmill, nor on calf blood flow, calf vascular resistance and skin temperature, when compared with placebo. No reports described adverse events associated with the beta blockers studied. Currently, no evidence suggests that beta blockers adversely affect walking distance, calf blood flow, calf vascular resistance and skin temperature in people with intermittent claudication. However, because of the lack of large published trials, beta blockers should be used with caution, if clinically indicated.

Is there diurnal variation of the vestibulosympathetic reflex: implications for orthostatic hypotension

Incidences of adverse cardiac events and orthostatic hypotension are associated with diurnal variations. The primary purpose of the present study was to determine if the vestibulosympathetic reflex (VSR) follows a diurnal variation in humans. We hypothesized that the VSR would be attenuated at night based on the relation between melatonin and the VSR. Arterial blood pressure, heart rate, calf blood flow, and muscle sympathetic nerve activity (MSNA) were measured in nine healthy subjects (28 ± 1 yr, 5 men and 4 women) at rest and during head-down rotation. Each subject was tested during the day at 11:34 ± 13 and again at night 22:10 ± 5. MSNA was significantly decreased at night compared with day (8 ± 1 vs. 11 ± 2 bursts/min, respectively, P < 0.02). Heart rate and arterial blood pressure at rest were significantly increased at night compared with day (heart rate: 70 ± 4 vs. 66 ± 4 beats/min and mean arterial blood pressure: 91 ± 2 vs. 87 ± 1 mmHg, respectively). MSNA and hemodynamic responses to head-down rotation were not significantly altered at night compared with day (changes of 3 ± 1 bursts/min and 25 ± 6% for MSNA and calf blood flow, respectively). The data indicate that MSNA at rest decreases during the late evening hours and exhibits a diurnal variation, whereas the VSR does not. In summary, diurnal variation of orthostatic hypotension in humans does not appear to be associated with changes in the VSR and MSNA at rest.

Individual Intake of Free-Choice Mineral Mix by Grazing Beef Cows May Be Less Than Typical Formulation Assumptions and Form of Selenium in Mineral Mix Affects Blood Se Concentrations of Cows and Their Suckling Calves

The objectives of this study were to determine (1) the individual ad libitum intake of mineral mix by beef cows managed under a year-long, fall-calving, forage-based production regimen and (2) if Se form in the mineral mix affected the blood Se concentrations of cows and suckling calves. Twenty-four late-gestation (6 to 8 months) Angus-cross cows (2.7 ± 0.8 years; body weight [BW] = 585 ± 58 kg) were blocked by BW and randomly assigned (n = 8) to a mineral supplement treatment (TRT) containing 35 ppm Se as either inorganic (ISe; sodium selenite), organic (OSe; Sel-Plex®), or a 1:1 combination of ISe/OSe (MIX). Cows commonly grazed a 10.1-ha predominately tall fescue pasture and had individual ad libitum access to TRT using in-pasture Calan gates. Cows calved from August to November and calves had common ad libitum access to creep feed and a mineral supplement that lacked Se. Cow jugular blood was taken at 28-day intervals (13 periods) and calf blood was taken with cows from birth through weaning. Individual cow mineral mix (mean = 54.0 ± 7.0 g/day, range = 97.3 to 27.9 ± 7.4 g/day) and Se (mean = 1.82 ± 0.25 mg/day, range = 3.31 to 0.95 ± 0.25 mg/day) intakes were affected by period (P < 0.0001), but not by cow Se TRT (P > 0.30). Cow blood Se (0.109 to 0.229 ± 0.01 μg/mL) was affected (P < 0.002) by period, Se form, and their interaction, with ISe < MIX for periods 8 and 11, ISe < OSe for all periods except period 1, and MIX < OSe for periods 2 to 4, 7, 8, 10, and 12. Calf blood Se (in micrograms Se per milliliter) was correlated with cow blood Se and affected (P < 0.0001) by cow Se TRT, with ISe (0.07 to 0.11) < MIX (0.10 to 0.15) = OSe (0.16 to 0.19). These data reveal that (1) mean supplemental ad libitum cow mineral intake was 36% less than the typical formulation intake expectations (85 g/day) and, correspondingly, mean supplemental Se intake was 33% less than that allowed by the FDA and (2) cow Se TRT differentially affected both cow and calf blood Se concentrations, resulting in adequate concentrations for all cows but inadequate concentrations for ISe calves.

Hemodynamic Responses to Resistance Exercise With Restricted Blood Flow in Young and Older Men

Exercise with blood flow restriction promotes significant improvements, and it has been considered an attractive exercise strategy, especially for older individuals. However, the acute cardiovascular responses to resistance exercise with blood flow restriction (BFR) are not fully known. The purpose of this study was to evaluate the hemodynamic responses during resistance exercise with BFR in young and older individuals. We compared hemodynamic responses in 15 young (30 ± 3 years) and 12 older (66 ± 7 years) subjects during low-intensity resistance biceps curl exercise with (BFR-RE) or without (RE) BFR in a random and crossover design. Heart rate (HR), mean blood pressure (MBP), calf blood flow (CBF), and calf vascular resistance (CVR) were evaluated. Both groups presented similar values at baseline. Compared with RE, HR and MBP were higher during BFR-RE for both the groups, and these changes were maintained during the recovery period. In both the groups, BFR-RE elicited larger decreases in CBF and increased CVR. Both groups showed a significant increase in double product during BFR-RE. In conclusion, resistance exercise with BFR elicits greater hemodynamic changes in healthy young and older subjects, with responses of similar magnitudes in both groups. The safety of BFR in clinical practice demands further study in vulnerable populations.

Interferential electrical stimulation improves peripheral vasodilatation in healthy individuals

Interferential electrical stimulation (IES), which may be linked to greater penetration of deep tissue, may restore blood flow by sympathetic nervous modulation; however, studies have found no association between the frequency and duration of the application and blood flow. We hypothesized that 30 min of IES applied to the ganglion stellate region might improve blood flow redistribution. The purpose of this study was to determine the effect of IES on metaboreflex activation in healthy individuals. Interferential electrical stimulation or a placebo stimulus (same protocol without electrical output) was applied to the stellate ganglion region in eleven healthy subjects (age 25±1.3 years) prior to exercise. Mean blood pressure (MBP), heart rate (HR), calf blood flow (CBF) and calf vascular resistance (CVR) were measured throughout exercise protocols (submaximal static handgrip exercise) and with recovery periods with or without postexercise circulatory occlusion (PECO+ and PECO -, respectively). Muscle metaboreflex control of calf vascular resistance was estimated by subtracting the area under the curve when circulation was occluded from the area under the curve from the AUC without circulatory occlusion. At peak exercise, increases in mean blood pressure were attenuated by IES (p<0.05), and the effect persisted under both the PECO+ and PECO- treatments. IES promoted higher CBF and lower CVR during exercise and recovery. Likewise, IES induced a reduction in the estimated muscle metaboreflex control (placebo, 21±5 units vs. IES, 6±3, p<0.01). Acute application of IES prior to exercise attenuates the increase in blood pressure and vasoconstriction during exercise and metaboreflex activation in healthy subjects.

Effects of Transcranial Direct Current Stimulation on Hemodynamic Responses to Pain

Painful (noxious) stimuli cause increases in heart rate blood pressure, and peripheral vascular resistance. This response is due to a both direct nociceptive reflex responses and conscious pain perception. Transcranial direct current stimulation (tDCS) is effective in modulating pain perception threshold in healthy volunteers and thus might be used to dissociate afferent (skin pain receptors) and efferent (cortical pain perception) components in the response to pain. We examined systemic (heart rate and blood pressure) and regional (calf blood flow/resistance) responses to cold pressor tests at 14, 7, and 0 °C before and after tDCS (active and sham) in 15 volunteers. All hemodynamic responses were graded with temperature (14&lt;7&lt;0 °C, P&lt;0.05). tDCS reduced the perceived pain score, but only at 14 °C (P&lt;0.05). This coincided with a slight reduction in peak heart rate response of ~1–2 beats. However, aside from this, tDCS had no effect on hemodynamic responses. Hence, tDCS may alter the pain perception threshold but this has minimal impact on nociceptive activation of cardiovascular centers.

PM.18 Maternal Resting Peripheral Blood Flow and Tissue Oxygenation in Pregnancies Complicated with Pre-Eclampsia and IUGR

BackgroundPre-eclampsia is characterised by hypertension and proteinuria and associated with systemic hypoperfusion of multiple maternal organs. Intrauterine growth restriction (IUGR) is a recognised complication of pre-eclampsia and the two conditions...

Eccentric-exercise induced inflammation attenuates the vascular responses to mental stress

Mental stress has been identified as a trigger of myocardial infarction (MI), with inflammation and vascular responses to mental stress independently implicated as contributing factors. This study examined whether inflammation moderates the vascular responses to mental stress. Eighteen healthy male participants completed a stress task under two counter balanced conditions. In the exercise condition, a morning bout of eccentric exercise (12×5 repetitions of unilateral eccentric knee extension at 120% intensity of concentric one repetition maximum) was used to increase levels of inflammatory-responsive cytokines during an afternoon stress session scheduled 6h later. In the control condition, participants sat and relaxed for 45min, 6h prior to the afternoon stress session. Forearm blood flow, calf blood flow (measured in the leg which completed the exercise task), blood pressure, heart rate and cardiac output were assessed at rest and in response to mental stress. As expected, interleukin-6 was higher (p=.02) 6h post exercise, i.e., at the start of the stress session, as compared to the no-exercise control condition. Mental stress increased forearm blood flow, calf blood flow, blood pressure, heart rate, and cardiac output in both conditions (p's<.001). Stress-induced calf blood flow was attenuated in the exercise condition compared to the control condition (p<.05) which was not the case for forearm blood flow. This study found that the inflammatory response to eccentric exercise attenuated the vascular responses to mental stress locally at the site of eccentric exercise-induced inflammation. The observed impairment in vascular responses to stress associated with increased levels of inflammation suggests a mechanism through which inflammation might increase the risk for MI.

Sex differences in sympathetic neural and limb vascular reactivity to mental stress in humans

Mental stress elicits a robust and consistent forearm vasodilation, but vascular reactivity in the calf remains inconsistent. It has been reported that calf vascular responses to MS may be sex dependent. Muscle sympathetic nerve activity (MSNA) is an important contributor to calf blood flow (CBF), yet the relations between sex, limb blood flow, and MSNA reactivity to mental stress have not been explored. We hypothesized that mental stress would elicit more dramatic vasodilation of the limbs in women and that this might be explained by reduced MSNA reactivity and/or blunted sympathetic vascular transduction. We measured heart rate (HR), mean arterial pressure (MAP), CBF, calf vascular conductance (CVC), forearm blood flow (FBF), forearm vascular conductance (FVC), and MSNA concurrently in 18 men (age: 23 ± 2 yr) and 16 women (age: 24 ± 2 yr) during 5 min of supine baseline and 5 min of mental stress. Mental stress elicited similar increases in MAP (Δ10 ± 1 vs. Δ11 ± 1 mmHg), HR (Δ16 ± 2 vs. Δ17 ± 2 beats/min), FBF (Δ81 ± 16% vs. Δ83 ± 15%), and FVC (Δ62 ± 13% vs. Δ65 ± 13%) in men and women, respectively. In contrast, CBF (Δ16 ± 8% vs. Δ37 ± 9%, P = 0.036) and CVC (Δ4 ± 7% vs. Δ24 ± 8%, P = 0.036) responses were exaggerated in women compared with men. Changes in FVC were significantly correlated with changes in CVC in women (r = 0.681, P = 0.004) but not in men. MSNA reactivity to mental stress was not different between men and women; however, changes in CVC were negatively correlated with increases of MSNA in men (r = -0.411, P = 0.045) but not in women. In conclusion, our data suggest different patterns of calf vascular reactivity to mental stress in men and women that might relate, in part, to altered vascular transduction of MSNA.

Pleiotropic neuroprotective and metabolic effects of Actovegin's mode of action

This article reviews the mechanisms of action of Actovegin in the context of its preclinical effects and new concepts in the pharmacological treatment of neurological disorders. Actovegin is an ultrafiltrate of calf blood, composed of more than 200 biological substances. The drug is used for a broad spectrum of diseases, including disturbances of peripheral and cerebral blood circulation, burns, impaired wound healing, radiation-induced damage and diabetic polyneuropathy. Actovegin is composed of small molecules present under normal physiological conditions, therefore pharmacokinetic and pharmacodynamic studies to determine its active substance are not feasible. Preclinical data have revealed that it improves metabolic balance by increasing glucose uptake and improving oxygen uptake under conditions of ischemia. Actovegin also resists the effects of gamma-irradiation and stimulates wound healing. More recent preclinical studies have suggested that anti-oxidative and anti-apoptotic mechanisms of action specifically underlie the neuroprotective properties of Actovegin. The drug has been found to exert these beneficial effects experimentally, in primary rat hippocampal neurons and in an STZ-rat model of diabetic polyneuropathy, while also providing evidence that it positively affects the functional recovery of neurons. Latest data suggest that Actovegin also has a positive influence on the NF-κB pathway, but many molecular and cellular pathways remain unexplored. In particular, Actovegin's influence on neuroplasticity, neurogenesis and neurotrophicity are questions that ideally should be answered by future research. Nevertheless, it is clear that the multifactorial and complex nature of Actovegin underlies its pleiotropic neuroprotective mechanisms of action and positive effect on clinical outcomes.

Buffalo umbilical cord blood collection and hematological comparison with peripheral blood of new born calf and its dam

The present study was carried out to explore the feasibility of umbilical cord blood collection and to compare its hematology with peripheral blood of new born calf and the adult buffalo. Jugular blood samples (7) were collected from new born calf and its dam and umbilical cord blood from passed placenta immediately after placental expulsion. These blood samples were analyzed for 22 hematological parameters. Statistical analysis of 22 hematological parameters from all the 3 sources indicated that 7 parameters, viz. WBC, LYM, MON, NEU, HGB, PLT, PCT % of calf and 12 parameters, viz. WBC, LYM, MON, NEU, EOS, BAS, LY %, NE %, HCT %, MCV, MCH, PCT % of adult blood, respectively, were significantly higher than the cord blood, and 3 parameters, viz. RBC, RDWc %, and MO % of adult blood were significantly lower than that of cord blood. A significant difference between cord blood and calf blood with respect to 7 parameters, viz. WBC, LYM, MON, NEU, HGB, PLT, PCT % proves that cord blood and calf blood are not exactly same regarding their cellular content. This difference in hematological parameters of cord blood may be helpful in immunomodulation so that it can be used in transplantation and represent the neonatal defense system against the earliest encountered pathogens.

Corneal subbasal nerve fiber regeneration in myopic patients after laser in situ keratomileusis.

A total of 26 myopic patients (52 eyes) underwent laser in situ keratomileusis. In vivo confocal microscopy revealed that most of the regenerated corneal subbasal nerve fibers in the corneal flap originated from the stump of corneal subbasal nerve fibers outside the ablation zone and extended towards the center of the cornea in all patients. Meanwhile, new fibers were also found to directly regenerate from deep in the stroma in some cases. Approximately 94% of regenerated corneal subbasal nerve fibers (73/78 eyes) regrew vertically into the peripheral central 6-mm circle area 1 month after surgery, 78% (28/36 eyes) grew into the central 3–6 mm area at 2 months, and 23% into the central 3-mm circle area at 3 months. In addition, there was no significant difference in corneal subbasal nerve fiber regenerative capacity between the basic fibroblast growth factor group and the 20% (v/v) deproteinized extract of calf blood group. The majority of corneal subbasal nerve fiber regeneration occurred from the stump of corneal subbasal nerve fibers outside the corneal flap, and the remaining growth occurred deep within the stroma.

Progress on the Design and Development of the Continuous‐Flow Total Artificial Heart

Cleveland Clinic's continuous-flow total artificial heart has one motor and one rotating assembly supported by a hydrodynamic bearing. The right hydraulic output is self regulated by passive axial movement of the rotating assembly to balance itself with the left output. The purpose of this article is to present progress in four areas of development: the automatic speed control system, self-regulation to balance right/left inlet pressures and flows, hemolysis testing using calf blood, and coupled electromagnetics (EMAG) and computational fluid dynamics (CFD) analysis. The relationships between functions of motor power and speed, systemic flow, and systemic vascular resistance (SVR) were used for the sensorless speed control algorithm and demonstrated close correlations. Based on those empirical relationships, systemic flow and SVR were calculated in the system module and showed good correlation with measured pump flow and SVR. The automatic system adjusted the pump's speed to obtain the target flow in response to the calculated SVR. Atrial pressure difference (left minus right atrial pressure) was maintained within ±10 mm Hg for a wide range of SVR/pulmonary vascular resistance ratios, demonstrating a wide margin of self-regulation under fixed-speed mode and 25% sinusoidally modulated speed mode. Hemolysis test results indicated acceptable values (normalized index of hemolysis <0.01 mg/dL). The coupled EMAG/CFD model was validated for use in further device development.

Calf foetal and early life nutrition on grazing conditions: metabolic and endocrine profiles and body composition during the growing phase

The aim of this study was to determine the effect of nutrition during foetal and lactation periods on calf growth and body composition, and their association with changes in metabolic and endocrine profiles during the calf first year of life on purebred (Hereford and Angus) and cross-bred (F1) dam offspring. Forty cross-bred calves and their dams (purebred--PU: Hereford and Angus, and cross-bred--CR: F1) were used in a randomized block design with a factorial arrangement of herbage allowance of native pastures (high: Hi-HA and low: Lo-HA), 4 vs. 2.5 kg dry matter/kg body weight (BW) and dam genotype (PU vs. CR). Calf BW and blood samples were collected monthly from birth to 380±15 days of age, and body composition was estimated by the urea dilution technique at weaning (142±15 days) and 380 days. Calf birthweight did not differ among groups but from birth to 380 days, and BW was reduced (p=0.046) in Lo-PU offspring. Although Lo-CR calves achieved similar BW than Hi-PU and Hi-CR offspring, they showed an increased fat in detriment of lean tissue deposition. At birth, plasma total protein was less (p=0.04), while plasma glucose, insulin or IGF-I tended or were greater (p<0.072) in Hi-HA than Lo-HA calves. Greater (p<0.03) plasma total protein and/or glucose concentrations during the first months of lactation were observed in CR offspring associated with the greater dam milk production. Although glucose concentrations did not differ among calf groups after weaning, plasma insulin was greater (p=0.004) in Hi-PU than other groups at 380 days. Consistent with the reduced BW, Lo-PU offspring presented the lowest (p=0.026) plasma IGF-I from birth to 380 days. Herbage allowance of native grasslands during calf foetal and lactation periods interacted with maternal heterosis to affect, in the short and/or long term, calf BW or body composition, and metabolic and endocrine profiles.

Sympathetic Activation and Vasoregulation in Response to Carbohydrate Ingestion in Patients With Congestive Heart Failure

BackgroundIn normal individuals, carbohydrate ingestion increases sympathetic vasoconstrictor activity but causes net vasodilatation in the same vascular bed. This study quantified the effects of carbohydrate ingestion on muscle sympathetic nerve activity (MSNA) and vasoregulation in patients with congestive heart failure (CHF). We hypothesized that high resting levels of MSNA in patients with CHF would blunt further increases in MSNA following carbohydrate ingestion and that their sympathetic activation would restrain vasodilatation. MethodsEleven patients with treated severe CHF and 11 age- and body mass index–matched normal controls (NCs) were studied for 2 hours after a high-carbohydrate meal. MSNA was measured by peroneal microneurography and calf blood flow by venous occlusion plethysmography. ResultsPatients with CHF had higher (P < 0.03) baseline MSNA (67 ± 4.0 bursts/100 beats) than NCs (51 ± 5.8 bursts/100 beats) and lower (P < 0.001) baroreflex sensitivity (2.1 ± 0.58 ms/mm Hg) than NCs (7.4 ± 1.2 ms/mm Hg). Carbohydrate ingestion was associated with a significant increase in MSNA (P < 0.05) and calf blood flow (P < 0.01) with unchanged blood pressure in CHF patients. The magnitude of responses in CHF patients was not significantly different from that in NCs, but vasodilatation was delayed significantly (by 30 minutes). ConclusionsDespite considerable resting sympathoexcitation and reduced baroreflex sensitivity, patients with CHF exhibited further increases in MSNA after carbohydrate ingestion, achieving levels similar to those after myocardial infarction. They also had temporally delayed vasodilatation, which could contribute to cachexia and muscle weakness in CHF patients. These observations suggest that high-carbohydrate meals may adversely affect CHF patients via altered autonomic tone and blood-flow patterns.

Neuroprotection in vascular dementia: A future path

The burden of cognitive disorders is likely to increase over the coming years due to both increased longevity and altered risk factor patterns, arising from changes in lifestyle, healthcare and society. Vascular dementia with its underlying heterogeneous pathology, is a challenge for clinicians, and is frequently further aggravated by overlap with other neurodegenerative processes. Current Alzheimer's disease drugs have had limited clinical efficacy in treating vascular dementia and none have been approved by major regulatory authorities specifically for this disease. Moving forward, a valid choice may be a multimodal therapy, as has already been successfully proven in Alzheimer's disease. Actovegin, a hemodialysate derived from calf blood, has been shown to have effects on a variety of cellular processes and a recent experimental study has revealed its neuroprotective mechanisms of action. These data, coupled with positive results from clinical trials in mixed dementia populations, have served as a foundation for the design of a new trial investigating the efficacy and disease-modifying effects of Actovegin in post-stroke cognitive impairment.

Effect of a simulated functional magnetic resonance imaging (fMRI) scanner on resting and exercise‐induced changes in cardiovascular (CV) function

fMRI scanning confounds real‐time recordings of brain neural and CV recordings and can produce claustrophobia‐induced anxiety. As such, separate data collection sessions are often required and the assumption made that resting and reflex‐mediated changes in CV function are consistent. This study determined if a simulated fMRI scanner affects cardiovascular function at rest, during isometric handgrip exercise (IHG) and a period of post‐exercise ischemia (PEI). On separate days, 9 healthy participants (4M/5F, 21 ± 1 years) had heart rate (HR), mean arterial pressure (MAP), and calf blood flow (CBF) measured while supine on a standard lab bed or a simulated fMRI scanner. After ~10 min of rest they performed a 90s IHG at 40% maximum force followed by 2 min of PEI (no exercise). Heart rate variability indices (HRV) and calf vascular resistance (CVR) were calculated to estimate autonomic innervation to the heart and blood vessels. At rest, CBF was lower and CVR higher (both, p&lt;0.05) in the simulated fMRI scanner with no differences in resting HR, MAP, or HRV. No differences in the CV responses to IHG or PEI were observed between conditions. These data suggest that the fMRI environment increased resting sympathetic vasoconstriction to the calf but did not influence the CV response to IHG or PEI.