Blood flow measurements in rats using four color microspheres during blockade of different vasopressor systems

The use of colored microspheres to adequately evaluate blood flow changes under different circumstances in the same rat has been validated with a maximum of three different colors due to methodological limitations. The aim of the present study was to validate the use of four different colors measuring four repeated blood flow changes in the same rat to assess the role of vasopressor systems in controlling arterial pressure (AP). Red (150,000), white (200,000), yellow (150,000), and blue (200,000) colored microspheres were infused into the left ventricle of 6 male Wistar rats 1) at rest and 2) after vasopressin (aAVP, 10 µg/kg, iv), 3) renin-angiotensin (losartan, 10 mg/kg, iv), and 4) sympathetic system blockade (hexamethonium, 20 mg/kg, iv) to determine blood flow changes. AP was recorded and processed with a data acquisition system (1-kHz sampling frequency). Blood flow changes were quantified by spectrophotometry absorption peaks for colored microsphere components in the tissues evaluated. Administration of aAVP and losartan slightly reduced the AP (-5.7 ± 0.5 and -7.8 ± 1.2 mmHg, respectively), while hexamethonium induced a 52 ± 3 mmHg fall in AP. The aAVP injection increased blood flow in lungs (78%), liver (117%) and skeletal muscle (>150%), while losartan administration enhanced blood flow in heart (126%), lungs (100%), kidneys (80%), and gastrocnemius (75%) and soleus (94%) muscles. Hexamethonium administration reduced only kidney blood flow (50%). In conclusion, four types of colored microspheres can be used to perform four repeated blood flow measurements in the same rat detecting small alterations such as changes in tissues with low blood flow.

Subacute effects of a maximal exercise bout on endothelium-mediated vasodilation in healthy subjects

We evaluated vascular reactivity after a maximal exercise test in order to determine whether the effect of exercise on the circulation persists even after interruption of the exercise. Eleven healthy sedentary volunteers (six women, age 28 ± 5 years) were evaluated before and after (10, 60, and 120 min) a maximal exercise test on a treadmill. Forearm blood flow (FBF) was measured by venous occlusion plethysmography before and during reactive hyperemia (RH). Baseline FBF, analyzed by the area under the curve, increased only at 10 min after exercise (P = 0.01). FBF in response to RH increased both at 10 and 60 min vs baseline (P = 0.004). Total excess flow for RH above baseline showed that vascular reactivity was increased up to 60 min after exercise (mean ± SEM, before: 526.4 ± 48.8; 10 min: 1053.0 ± 168.2; 60 min: 659.4 ± 44.1 ml 100 ml-1 min-1 . s; P = 0.01 and 0.02, respectively, vs before exercise). The changes in FBF were due to increased vascular conductance since mean arterial blood pressure did not change. In a time control group (N = 5, 34 ± 3 years, three women) that did not exercise, FBF and RH did not change significantly (P = 0.07 and 0.7, respectively). These results suggest that the increased vascular reactivity caused by chronic exercise may result, at least in part, from a summation of the subacute effects of successive exercise bouts.

The biological effects of high-pressure gas on the yeast transcriptome

The aim of the present study was to examine the feasibility of DNA microarray technology in an attempt to construct an evaluation system for determining gas toxicity using high-pressure conditions, as it is well known that pressure increases the concentration of a gas. As a first step, we used yeast (Saccharomyces cerevisiae) as the indicator organism and analyzed the mRNA expression profiles after exposure of yeast cells to nitrogen gas. Nitrogen gas was selected as a negative control since this gas has low toxicity. Yeast DNA microarray analysis revealed induction of genes whose products were localized to the membranes, and of genes that are involved in or contribute to energy production. Furthermore, we found that nitrogen gas significantly affected the transport system in the cells. Interestingly, nitrogen gas also resulted in induction of cold-shock responsive genes. These results suggest the possibility of applying yeast DNA microarray to gas bioassays up to 40 MPa. We therefore think that "bioassays" are ideal for use in environmental control and protection studies.

Effect of high hydrostatic pressure on the barrier properties of polyamide-6 films

Little is known about the barrier properties of polymer films during high pressure processing of prepackaged foods. In order to learn more about this, we examined the influence of high hydrostatic pressure on the permeation of raspberry ketone (dissolved in ethanol/water) through polyamide-6 films at temperatures between 20 and 60ºC. Permeation was lowered by increasing pressure at all temperatures. At 23°C, the increasing pressure sequence 0.1, 50, 100, 150, and 200 MPa correlated with the decreasing permeation coefficients P/(10(9) cm² s-1) of 6.2, 3.8, 3.0, 2.2, and 1.6. Analysis of the permeation kinetics indicated that this effect was due to a reduced diffusion coefficient. Pressure and temperature acted antagonistically to each other. The decrease in permeation at 200 MPa was compensated for by a temperature increase of 20ºC. After release of pressure, the former permeation coefficients were recovered, which suggests that this `pressure effect' is reversible. Taken together, our data revealed no detrimental effects of high hydrostatic pressure on the barrier properties of polymer films.

Effect of intraperitoneally administered hydrolyzed whey protein on blood pressure and renal sodium handling in awake spontaneously hypertensive rats

The present study evaluated the acute effect of the intraperitoneal (ip) administration of a whey protein hydrolysate (WPH) on systolic arterial blood pressure (SBP) and renal sodium handling by conscious spontaneously hypertensive rats (SHR). The ip administration of WPH in a volume of 1 ml dose-dependently lowered the SBP in SHR 2 h after administration at doses of 0.5 g/kg (0.15 M NaCl: 188.5 ± 9.3 mmHg vs WPH: 176.6 ± 4.9 mmHg, N = 8, P = 0.001) and 1.0 g/kg (0.15 M NaCl: 188.5 ± 9.3 mmHg vs WPH: 163.8 ± 5.9 mmHg, N = 8, P = 0.0018). Creatinine clearance decreased significantly (P = 0.0084) in the WPH-treated group (326 ± 67 µL min-1 100 g body weight-1) compared to 0.15 M NaCl-treated (890 ± 26 µL min-1 100 g body weight-1) and captopril-treated (903 ± 72 µL min-1 100 g body weight-1) rats. The ip administration of 1.0 g WPH/kg also decreased fractional sodium excretion to 0.021 ± 0.019% compared to 0.126 ± 0.041 and 0.66 ± 0.015% in 0.15 M NaCl and captopril-treated rats, respectively (P = 0.033). Similarly, the fractional potassium excretion in WPH-treated rats (0.25 ± 0.05%) was significantly lower (P = 0.0063) than in control (0.91 ± 0.15%) and captopril-treated rats (1.24 ± 0.30%), respectively. The present study shows a decreased SBP in SHR after the administration of WPH associated with a rise in tubule sodium reabsorption despite an angiotensin I-converting enzyme (ACE)-inhibiting in vitro activity (IC50 = 0.68 mg/mL). The present findings suggest a pathway involving ACE inhibition but measurements of plasma ACE activity and angiotensin II levels are needed to support this suggestion.

Effects of diet and exercise training on neurovascular control during mental stress in obese women

Since neurovascular control is altered in obese subjects, we hypothesized that weight loss by diet (D) or diet plus exercise training (D + ET) would improve neurovascular control during mental stress in obese women. In a study with a dietary reduction of 600 kcal/day with or without exercise training for 4 months, 53 obese women were subdivided in D (N = 22, 33 ± 1 years, BMI 34 ± 1 kg/m²), D + ET (N = 22, 33 ± 1 years, BMI 33 ± 1 kg/m²), and nonadherent (NA, N = 9, 35 ± 2 years, BMI 33 ± 1 kg/m²) groups. Muscle sympathetic nerve activity (MSNA) was measured by microneurography and forearm blood flow by venous occlusion plethysmography. Mental stress was elicited by a 3-min Stroop color word test. Weight loss was similar between D and D + ET groups (87 ± 2 vs 79 ± 2 and 85 ± 2 vs 76 ± 2 kg, respectively, P < 0.05) with a significant reduction in MSNA during mental stress (58 ± 2 vs 50 ± 2, P = 0.0001, and 59 ± 3 vs 50 ± 2 bursts/100 beats, P = 0.0001, respectively), although the magnitude of the response was unchanged. Forearm vascular conductance during mental stress was significantly increased only in D + ET (2.74 ± 0.22 vs 3.52 ± 0.19 units, P = 0.02). Weight loss reduces MSNA during mental stress in obese women. The increase in forearm vascular conductance after weight loss provides convincing evidence for D + ET interventions as a nonpharmacologic therapy of human obesity.

The decreased oxygen uptake during progressive exercise in ischemia-induced heart failure is due to reduced cardiac output rate

We tested the hypothesis that the inability to increase cardiac output during exercise would explain the decreased rate of oxygen uptake (VO2) in recent onset, ischemia-induced heart failure rats. Nine normal control rats and 6 rats with ischemic heart failure were studied. Myocardial infarction was induced by coronary ligation. VO2 was measured during a ramp protocol test on a treadmill using a metabolic mask. Cardiac output was measured with a flow probe placed around the ascending aorta. Left ventricular end-diastolic pressure was higher in ischemic heart failure rats compared with normal control rats (17 ± 0.4 vs 8 ± 0.8 mmHg, P = 0.0001). Resting cardiac index (CI) tended to be lower in ischemic heart failure rats (P = 0.07). Resting heart rate (HR) and stroke volume index (SVI) did not differ significantly between ischemic heart failure rats and normal control rats. Peak VO2 was lower in ischemic heart failure rats (73.72 ± 7.37 vs 109.02 ± 27.87 mL min-1 kg-1, P = 0.005). The VO2 and CI responses during exercise were significantly lower in ischemic heart failure rats than in normal control rats. The temporal response of SVI, but not of HR, was significantly lower in ischemic heart failure rats than in normal control rats. Peak CI, HR, and SVI were lower in ischemic heart failure rats. The reduction in VO2 response during incremental exercise in an ischemic model of heart failure is due to the decreased cardiac output response, largely caused by depressed stroke volume kinetics.

Development of project cash flow forecasting process

Process management refers to improving the key functions of a company. The main functions of the case company - project management, procurement, finance, and human resource - use their own separate systems. The case company is in the process of changing its software. Different functions will use the same system in the future. This software change causes changes in some of the company’s processes. Project cash flow forecasting process is one of the changing processes. Cash flow forecasting ensures the sufficiency of money and prepares for possible changes in the future. This will help to ensure the company’s viability. The purpose of the research is to describe a new project cash flow forecasting process. In addition, the aim is to analyze the impacts of the process change, with regard to the project control department’s workload and resources through the process measurement, and how the impacts take the department’s future operations into account. The research is based on process management. Processes, their descriptions, and the way the process management uses the information, are discussed in the theory part of this research. The theory part is based on literature and articles. Project cash flow and forecasting-related benefits are also discussed. After this, the project cash flow forecasting as-is and to-be processes are described by utilizing information, obtained from the theoretical part, as well as the know-how of the project control department’s personnel. Written descriptions and cross-functional flowcharts are used for descriptions. Process measurement is based on interviews with the personnel – mainly cost controllers and department managers. The process change and the integration of two processes will allow work time for other things, for example, analysis of costs. In addition to the quality of the cash flow information will improve compared to the as-is process. Analyzing the department’s other main processes, department’s roles, and their responsibilities should be checked and redesigned. This way, there will be an opportunity to achieve the best possible efficiency and cost savings.

Sodium taste threshold in children and its relationship to blood pressure

Popular science has emphasized the risks of high sodium intake and many studies have confirmed that salt intake is closely related to hypertension. The present mini-review summarizes experiments about salt taste sensitivity and its relationship with blood pressure (BP) and other variables of clinical and familial relevance. Children and adolescents from control parents (N = 72) or with at least one essential hypertensive (EHT) parent (N = 51) were investigated. Maternal questionnaires on eating habits and vomiting episodes were collected. Offspring, anthropometric, BP, and salt taste sensitivity values were recorded and blood samples analyzed. Most mothers declared that they added "little salt" when cooking. Salt taste sensitivity was inversely correlated with systolic BP (SBP) in control youngsters (r = -0.33; P = 0.015). In the EHT group, SBP values were similar to control and a lower salt taste sensitivity threshold. Obese offspring of EHT parents showed higher SBP and C-reactive protein values but no differences in renin-angiotensin-aldosterone system activity. Salt taste sensitivity was correlated with SBP only in the non-obese EHT group (N = 41; r = 0.37; P = 0.02). Salt taste sensitivity was correlated with SBP in healthy, normotensive children and adolescents whose mothers reported significant vomiting during the first trimester (N = 18; r = -0.66; P < 0.005), but not in "non-vomiter offspring" (N = 54; r = -0.18; nonsignificant). There is evidence for a linkage between high blood pressure, salt intake and sensitivity, perinatal environment and obesity, with potential physiopathological implications in humans. This relationship has not been studied comprehensively using homogeneous methods and therefore more research is needed in this field.

Role of nitric oxide and prostaglandin in the maintenance of cortical and renal medullary blood flow

This study was undertaken in anesthetized dogs to evaluate the relative participation of prostaglandins (PGs) and nitric oxide (NO) in the maintenance of total renal blood flow (TRBF), and renal medullary blood flow (RMBF). It was hypothesized that the inhibition of NO should impair cortical and medullary circulation because of the synthesis of this compound in the endothelial cells of these two territories. In contrast, under normal conditions of perfusion pressure PG synthesis is confined to the renal medulla. Hence PG inhibition should predominantly impair the medullary circulation. The initial administration of 25 µM kg-1 min-1 NG-nitro-L-arginine methyl ester produced a significant 26% decrease in TRBF and a concomitant 34% fall in RMBF, while the subsequent inhibition of PGs with 5 mg/kg meclofenamate further reduced TRBF by 33% and RMBF by 89%. In contrast, the initial administration of meclofenamate failed to change TRBF, while decreasing RMBF by 49%. The subsequent blockade of NO decreased TRBF by 35% without further altering RMBF. These results indicate that initial PG synthesis inhibition predominantly alters the medullary circulation, whereas NO inhibition decreases both cortical and medullary flow. This latter change induced by NO renders cortical and RMBF susceptible to a further decrease by PG inhibition. However, the decrease in medullary circulation produced by NO inhibition is not further enhanced by subsequent PG inhibition.

Is persistent hypotension after transient cardiogenic shock associated with an inflammatory response?

We evaluated the recovery of cardiovascular function after transient cardiogenic shock. Cardiac tamponade was performed for 1 h and post-shock data were collected in 5 domestic large white female pigs (43 ± 5 kg) for 6 h. The control group (N = 5) was observed for 6 h after 1 h of resting. During 1 h of cardiac tamponade, experimental animals evolved a low perfusion status with a higher lactate level (8.0 ± 2.2 vs 1.9 ± 0.9 mEq/L), lower standard base excess (-7.3 ± 3.3 vs 2.0 ± 0.9 mEq/L), lower urinary output (0.9 ± 0.9 vs 3.0 ± 1.4 mL·kg-1·h-1), lower mixed venous saturation, higher ileum partial pressure of CO2-end tidal CO2 (EtCO2) gap and a lower cardiac index than the control group. Throughout the 6-h recovery phase after cardiac tamponade, tamponade animals developed significant tachycardia with preserved cardiac index, resulting in a lower left ventricular stroke work, suggesting possible myocardial dysfunction. Vascular dysfunction was present with persistent systemic hypotension as well as persistent pulmonary hypertension. In contrast, oliguria, hyperlactatemia and metabolic acidosis were corrected by the 6th hour. The inflammatory characteristics were an elevated core temperature and increased plasma levels of interleukin-6 in the tamponade group compared to the control group. We conclude that cardiovascular recovery after a transient and severe low flow systemic state was incomplete. Vascular dysfunction persisted up to 6 h after release of tamponade. These inflammatory characteristics may also indicate that inflammatory activation is a possible pathway involved in the pathogenesis of cardiogenic shock.

Flow rate, pH and calcium concentration of saliva of children and adolescents with type 1 diabetes mellitus

Alterations in salivary parameters may increase the caries risk in diabetic children, but, contradictory data on this issue have been reported. The aims of this study were to compare salivary parameters (flow rate, pH and calcium concentration) between healthy and type 1 diabetes mellitus (T1DM) individuals. The sample consisted of 7- to 18-year-old individuals divided into two groups: 30 subjects with T1DM (group A) and 30 healthy control subjects (group B). Fasting glucose levels were determined. Unstimulated and stimulated saliva was collected. The pH of unstimulated saliva was measured with paper strips and an electrode. Calcium concentrations in stimulated saliva were determined with a selective electrode. Group A individuals had inadequate blood glucose control (HbA1C >9%), with means ± SD unstimulated salivary flow rate of 0.15 ± 0.1 mL/min compared to 0.36 ± 0.2 mL/min for group B (P < 0.01). Stimulated salivary flow rate was similar by both groups and above 2.0 mL/min. Saliva pH was 6.0 ± 0.8 for group A and significantly different from 7.0 ± 0.6 for group B (P < 0.01). Salivary calcium was 14.7 ± 8.1 mg/L for group A and significantly higher than 9.9 ± 6.4 mg/L for group B (P < 0.01). Except for elevated calcium concentrations in saliva, salivary parameters favoring caries such as low saliva pH and unstimulated salivary flow rate were observed in T1DM individuals.

Tonic and reflex cardiovascular autonomic control in trained-female rats

The effects of exercise training on cardiovascular and autonomic functions were investigated in female rats. After an aerobic exercise training period (treadmill: 5 days/week for 8 weeks), conscious female Wistar (2 to 3 months) sedentary (S, N = 7) or trained rats (T, N = 7) were cannulated for direct arterial pressure (AP) recording in the non-ovulatory phases. Vagal (VT) and sympathetic tonus (ST) were evaluated by vagal (atropine) and sympathetic (propranolol) blockade. Baroreflex sensitivity was evaluated by the heart rate responses induced by AP changes. Cardiopulmonary reflex was measured by the bradycardic and hypotensive responses to serotonin. Resting bradycardia was observed in T (332 ± 7 bpm) compared with S animals (357 ± 10 bpm), whereas AP did not differ between groups. T animals exhibited depressed VT and ST (32 ± 7 and 15 ± 4 bpm) compared to S animals (55 ± 5 and 39 ± 10 bpm). The baroreflex and cardiopulmonary bradycardic responses were lower in T (-1.01 ± 0.27 bpm/mmHg and -17 ± 6 bpm) than in the S group (-1.47 ± 0.3 bpm/mmHg and -41 ± 9 bpm). Significant correlations were observed between VT and baroreflex (r = -0.72) and cardiopulmonary (r = -0.76) bradycardic responses. These data show that exercise training in healthy female rats induced resting bradycardia that was probably due to a reduced cardiac ST. Additionally, trained female rats presented attenuated bradycardic responses to baro- and cardiopulmonary receptor stimulation that were associated, at least in part, with exercise training-induced cardiac vagal reduction.

Control of respiration in fish, amphibians and reptiles

Fish and amphibians utilise a suction/force pump to ventilate gills or lungs, with the respiratory muscles innervated by cranial nerves, while reptiles have a thoracic, aspiratory pump innervated by spinal nerves. However, fish can recruit a hypobranchial pump for active jaw occlusion during hypoxia, using feeding muscles innervated by anterior spinal nerves. This same pump is used to ventilate the air-breathing organ in air-breathing fishes. Some reptiles retain a buccal force pump for use during hypoxia or exercise. All vertebrates have respiratory rhythm generators (RRG) located in the brainstem. In cyclostomes and possibly jawed fishes, this may comprise elements of the trigeminal nucleus, though in the latter group RRG neurons have been located in the reticular formation. In air-breathing fishes and amphibians, there may be separate RRG for gill and lung ventilation. There is some evidence for multiple RRG in reptiles. Both amphibians and reptiles show episodic breathing patterns that may be centrally generated, though they do respond to changes in oxygen supply. Fish and larval amphibians have chemoreceptors sensitive to oxygen partial pressure located on the gills. Hypoxia induces increased ventilation and a reflex bradycardia and may trigger aquatic surface respiration or air-breathing, though these latter activities also respond to behavioural cues. Adult amphibians and reptiles have peripheral chemoreceptors located on the carotid arteries and central chemoreceptors sensitive to blood carbon dioxide levels. Lung perfusion may be regulated by cardiac shunting and lung ventilation stimulates lung stretch receptors.

Effects of different levels of positive airway pressure on breathing pattern and heart rate variability after coronary artery bypass grafting surgery

The application of continuous positive airway pressure (CPAP) produces important hemodynamic alterations, which can influence breathing pattern (BP) and heart rate variability (HRV). The aim of this study was to evaluate the effects of different levels of CPAP on postoperative BP and HRV after coronary artery bypass grafting (CABG) surgery and the impact of CABG surgery on these variables. Eighteen patients undergoing CABG were evaluated postoperatively during spontaneous breathing (SB) and application of four levels of CPAP applied in random order: sham (3 cmH2O), 5 cmH2O, 8 cmH2O, and 12 cmH2O. HRV was analyzed in time and frequency domains and by nonlinear methods and BP was analyzed in different variables (breathing frequency, inspiratory tidal volume, inspiratory and expiratory time, total breath time, fractional inspiratory time, percent rib cage inspiratory contribution to tidal volume, phase relation during inspiration, phase relation during expiration). There was significant postoperative impairment in HRV and BP after CABG surgery compared to the preoperative period and improvement of DFAα1, DFAα2 and SD2 indexes, and ventilatory variables during postoperative CPAP application, with a greater effect when 8 and 12 cmH2O were applied. A positive correlation (P < 0.05 and r = 0.64; Spearman) was found between DFAα1 and inspiratory time to the delta of 12 cmH2O and SB of HRV and respiratory values. Acute application of CPAP was able to alter cardiac autonomic nervous system control and BP of patients undergoing CABG surgery and 8 and 12 cmH2O of CPAP provided the best performance of pulmonary and cardiac autonomic functions.