Catecholamine release in heat-stressed Antarctic fish causes proton extrusion by the red cells

Two species of Antarctic fish were stressed by moving them from seawater at -1 degrees C to seawater at 10 degrees C and holding them for a period of 10 min. The active cryopelagic species Pagothenia borchgrevinki maintained heart rate while in the benthic species Trematomus bernacchii there was an increase in heart rate. Blood pressure did not change in either species. Both species released catecholamines into the circulation as a consequence of the stress. P. borchgrevinki released the greater amounts, having mean plasma concentrations of 177 +/- 54 nmol.l(-1) noradrenaline and 263 +/- 131 nmol.l(-1) adrenaline at 10 min. Pla.sma noradrenaline concentrations rose to 47 +/- 14 nmol.l(-1) and adrenaline to 73 +/- 28 nmol.l(-1) in T. bernacchii. Blood from P. borchgrevinki was tonometered in the presence of isoprenaline. A fall in extracellular pH suggests the presence of a Na+/H+ antiporter on the red cell membrane, the first demonstration of this in an Antarctic fish. Treatment with the beta-adrenergic antagonist drug sotalol inhibited swelling of red blood cells taken from temperature-stressed P. borchgrevinki, suggesting that the antiporter responds to endogenous catecholamines.

A comparison of methods to identify open-lung PEEP

Purpose: Many methods exist in the literature for identifying PEEP to set in ARDS patients following a lung recruitment maneuver (RM). We compared ten published parameters for setting PEEP following a RM. Methods: Lung injury was induced by bilateral lung lavage in 14 female Dorset sheep, yielding a PaO(2) 100-150 mmHg at F(I)O(2) 1.0 and PEEP 5 cmH(2)O. A quasi-static P-V curve was then performed using the supersyringe method; PEEP was set to 20 cmH(2)O and a RM performed with pressure control ventilation (inspiratory pressure set to 40-50 cmH(2)O), until PaO(2) + PaCO(2) > 400 mmHg. Following the RM, a decremental PEEP trial was performed. The PEEP was decreased in 1 cmH(2)O steps every 5 min until 15 cmH(2)O was reached. Parameters measured during the decremental PEEP trial were compared with parameters obtained from the P-V curve. Results: For setting PEEP, maximum dynamic tidal respiratory compliance, maximum PaO(2), maximum PaO(2) + PaCO(2), and minimum shunt calculated during the decremental PEEP trial, and the lower Pflex and point of maximal compliance increase on the inflation limb of the P-V curve (Pmci,i) were statistically indistinguishable. The PEEP value obtained using the deflation upper Pflex and the point of maximal compliance decrease on the deflation limb were significantly higher, and the true inflection point on the inflation limb and minimum PaCO(2) were significantly lower than the other variables. Conclusion: In this animal model of ARDS, dynamic tidal respiratory compliance, maximum PaO(2), maximum PaO(2) + PaCO(2), minimum shunt, inflation lower Pflex and Pmci,i yield similar values for PEEP following a recruitment maneuver.

Cardiovascular responses to noradrenaline microinjection in the ventrolateral periaqueductal gray of unanesthetized rats

The periaqueductal gray area (PAG) is a mesencephalic area involved in cardiovascular modulation. Noradrenaline (NA), a neurotransmitter involved in central blood pressure control, is present in the rat PAG. We report here on the cardiovascular effects caused by NA microinjection into the ventrolateral PAG (vlPAG) of unanesthetized rats and the peripheral mechanism involved in their mediation. NA microinjection in the vlPAG of unanesthetized rats evoked dose-related pressor and bradycardiac responses. No significant cardiovascular responses were observed in urethane-anesthetized rats. The pressor response was potentiated by pretreatment with the ganglion blocker pentolinium (5 or 10 mg/kg, intravenously). Pretreatment with the vasopressin antagonist dTyr(CH(2))(5) (Me)AVP (50 mu g/kg, intravenously) blocked the pressor response evoked by the NA microinjection into the vlPAG. Additionally, circulating vasopressin content was found to be significantly increased after NA microinjection in the vlPAG. The results suggest that activation of noradrenergic synapses within the vlPAG modulates vasopressin release in unanesthetized rats. (c) 2007 Wiley-Liss, Inc.

Antihypertensive effects exerted by enalapril in mild to moderate hypertension are not associated with changes in the circulating levels of nitric oxide-related markers

The antihypertensive effects of angiotensin-converting enzyme inhibitors (ACEi) are explained, at least in part, by enhanced bradykinin-dependent nitric oxide (NO) formation and decreased angiotensin II-induced oxidative stress and vasoconstriction. We examined for the first time whether treatment with enalapril increases the plasma levels of markers of NO formation and decreases oxidative stress in mild to moderate hypertensive patients. Eighteen untreated hypertensive patients were treated with enalapril 10 mg/day (n = 10) or 20 mg/day (n = 8) for 60 days. Eighteen normotensive healthy controls were followed for the same period. Venous blood samples were collected at baseline and after 30/60 days of treatment with enalapril. Plasma NOx (nitrites + nitrates) concentrations were determined by using the Griess reaction. Plasma nitrite and whole blood nitrite concentrations were determined by using an ozone-based chemiluminescence assay. Plasma thiobarbituric acid-reactive species (TBARS) and 8-isoprostane concentrations were determined by a fluorimetric method and by ELISA, respectively. Treatment with enalapril decreased blood pressure in hypertensive patients. However, we found no significant changes in plasma NOx, nitrite, whole blood nitrite, and in the levels of markers of oxidative stress in both normotensive controls and hypertensive patients treated with enalapril. Our data show that enalapril 10-20 mg/day does not affect the concentrations of relevant markers of NO formation or markers of oxidative stress in mild to moderately hypertensive subjects, despite satisfactory blood pressure control. Our findings do not rule out the possibility that ACEi may produce such effects in more severely hypertensive patients treated with higher doses of ACEi.

Associations between human liver and kidney cadmium content and immunochemically detected CYP4A11 apoprotein

This present study was undertaken to assess potential effects of cadmium on CYP4A11 apoprotein in human liver and kidney as detected by Western blotting using a highly specific anti-peptide antibody. Liver and kidney cortex samples were autopsy specimens of 37 individuals (26 mates and I I females) whose ages ranged from 3 to 89 years. All were Caucasians who had not been exposed to cadmium in the workplace. Reduced CYP4A11 apoprotein levels were found in chronic hepatitis samples and in liver samples showing fatty changes. In contrast, increased CYP4A11 apoprotein levels were found in liver samples having higher cadmium content compared to the lower cadmium content samples. Increased CYP4A11 levels were also found in liver samples from female donors, compared to male donors; the difference being attributable to higher female liver cadmium burden. In distinction to liver, lowered CYP4A11 levels were seen in the kidney cortex samples which have high cadmium content, It is proposed here that the difference between the absolute cadmium burden of the liver and kidney samples may be responsible for the different patterns of expression of CYP4A11 in these two tissues. Further, since cadmium exposure may be associated with derangement in blood pressure control, it is interesting to note the possible relationship between altered CYP4A11-dependent production of arachidonic acid hydroxy and epoxy metabolites in kidney cortex and altered control of blood pressure. Our findings provide a possible link between these observations. (C) 2002 Elsevier Science Inc. All rights reserved.

Desenvolvimento de um plano de manutenção preventiva na rede de distribuição de água de Lisboa

O presente relatório de estágio enquadra-se no âmbito do trabalho final de Mestrado do curso de Engenharia Civil, área de especialização em Hidráulica, do Instituto Superior de Engenharia de Lisboa, e incide na temática dos sistemas de distribuição de água. O estágio decorreu na empresa EPAL – Empresa Portuguesa das Águas Livres, S.A., e teve como objecto o desenvolvimento de um plano de manutenção preventiva para a rede de distribuição de água de Lisboa. Devido à crescente complexidade dos sistemas de abastecimento de água e à grande dispersão territorial dos diversos órgãos integrados na rede, surge a necessidade de desenvolver um sistema que permita simplificar o planeamento e a gestão das intervenções de inspecção e manutenção preventiva dos órgãos. Para esse efeito, recorreu-se a um software SIG (Sistema de Informação Geográfica) para proceder à sectorização da rede de distribuição de água em pequenos grupos (Polígonos), constituídos por um número determinado de órgãos de manobra e segurança. Esta metodologia permite organizar as intervenções em pequenos grupos e optimizar as rotinas de Inspecção diárias. No decorrer do estágio efectuou-se ainda um levantamento dos procedimentos de inspecção e manutenção dos diversos órgãos integrados na rede de distribuição de água de Lisboa, quer por acompanhamento de actividades com as equipas de inspecção, quer por recolha de recomendações junto dos fabricantes dos órgãos. Este levantamento permitiu elaborar fichas de procedimento para as actividades de inspecção e manutenção preventiva dos diversos órgãos, afim de serem usadas como referência pelos trabalhadores.

Coletores de distribuição e sua otimização hidráulica, aplicados a uma instalação de produção de água arrefecida em sistemas de AVAC ( Fórum Picoas)

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica

Health-Related Quality of Life Impact of a Triple Combination of Olmesartan Medoxomil, Amlodipine Besylate and Hydrochlorotiazide in Subjects with Hypertension

BACKGROUND: A post-hoc analysis was performed on the data from a 54 weeks phase III study (ClinicalTrials.gov identifier: NCT00923091) to measure changes in the health-related quality of life (HRQoL) of 2,690 patients aged ≥18 with moderate-to-severe hypertension who received one of six doses of olmesartan/amlodipine/hydrochlorothiazide (OLM/AML/HCTZ), using the MINICHAL and EQ-5D instruments. METHODS: Descriptive statistics were used to assess blood pressure and HRQoL scores over the study period. Analysis of covariance (ANCOVA) was used to identify those factors that could possibly have influenced HRQoL. Linear regression was used to assess the relationship between changes in blood pressure and HRQoL scores. RESULTS: Patients' baseline MINICHAL mood and somatic domains scores were 5.5 and 2.6. Over the study period HRQoL improved as both MINICHAL scores decreased by 31-33%. Patients' baseline EQ-5D index and VAS scores were 0.9 and 73.4 respectively, increasing by 6% and 12% over the study period. Patients' QALY gain over the 54 weeks study period was estimated to be 0.029 QALYs. The ANCOVA showed that changes in patients' HRQoL was likely to have been influenced by patients' achievement of blood pressure control, the amount of concomitant medication and patients' last used dosage strength of antihypertensive. Linear regression showed that blood pressure improvement may have been associated with improved HRQoL. CONCLUSIONS: This study showed that OLM/AML/HCTZ reduced blood pressure and significantly increased blood pressure control whilst improving patients' HRQoL. Achieving blood pressure control, amount of concomitant medication and dosage strength of antihypertensive impacted on patients' HRQoL.

40 K Neon liquid energy storage unit

Cryocoolers have been progressively replacing the use of the stored cryogens in cryogenic chains used for detector cooling, thanks to their higher and higher reliability. However, the mechanical vibrations, the electromagnetic interferences and the temperature fluctuations inherent to their functioning could reduce the sensor’s sensitivity. In order to minimize this problem, compact thermal energy storage units (ESU) are studied, devices able to store thermal energy without significant temperature increase. These devices can be used as a temporary cold source making it possible to turn the cryocooler OFF providing a proper environment for the sensor. A heat switch is responsible for the thermal decoupling of the ESU from the cryocooler’s temperature that increases when turned OFF. In this work, several prototypes working around 40 K were designed, built and characterized. They consist in a low temperature cell that contains the liquid neon connected to an expansion volume at room temperature for gas storage during the liquid evaporation phase. To turn this system insensitive to the gravity direction, the liquid is retained in the low temperature cell by capillary effect in a porous material. Thanks to pressure regulation of the liquid neon bath, 900 J were stored at 40K. The higher latent heat of the liquid and the inexistence of triple point transitions at 40 K turn the pressure control during the evaporation a versatile and compact alternative to an ESU working at the triple point transitions. A quite compact second prototype ESU directly connected to the cryocooler cold finger was tested as a temperature stabilizer. This device was able to stabilize the cryocooler temperature ((≈ 40K ±1 K) despite sudden heat bursts corresponding to twice the cooling power of the cryocooler. This thesis describes the construction of these devices as well as the tests performed. It is also shown that the thermal model developed to predict the thermal behaviour of these devices, implemented as a software,describes quite well the experimental results. Solutions to improve these devices are also proposed.

40 K neon liquid energy storage unit

Cryocoolers have been progressively replacing the use of the stored cryogens in cryogenic chains used for detector cooling, thanks to their higher and higher reliability. However, the mechanical vibrations, the electromagnetic interferences and the temperature fluctuations inherent to their functioning could reduce the sensor’s sensitivity. In order to minimize this problem, compact thermal energy storage units (ESU) are studied, devices able to store thermal energy without significant temperature increase. These devices can be used as a temporary cold source making it possible to turn the cryocooler OFF providing a proper environment for the sensor. A heat switch is responsible for the thermal decoupling of the ESU from the cryocooler’s temperature that increases when turned OFF. In this work, several prototypes working around 40 K were designed, built and characterized. They consist in a low temperature cell that contains the liquid neon connected to an expansion volume at room temperature for gas storage during the liquid evaporation phase. To turn this system insensitive to the gravity direction, the liquid is retained in the low temperature cell by capillary effect in a porous material. Thanks to pressure regulation of the liquid neon bath, 900 J were stored at 40K. The higher latent heat of the liquid and the inexistence of triple point transitions at 40 K turn the pressure control during the evaporation a versatile and compact alternative to an ESU working at the triple point transitions. A quite compact second prototype ESU directly connected to the cryocooler cold finger was tested as a temperature stabilizer. This device was able to stabilize the cryocooler temperature ((≈ 40K ±1 K) despite sudden heat bursts corresponding to twice the cooling power of the cryocooler. This thesis describes the construction of these devices as well as the tests performed. It is also shown that the thermal model developed to predict the thermal behaviour of these devices,implemented as a software, describes quite well the experimental results. Solutions to improve these devices are also proposed.

Aproveitamento de energia em sistemas de abastecimento de água

Dissertação de mestrado integrado em Engenharia Civil

Retinal Detachment in Preeclampsia

Preeclampsia is an obstetric disease of unknown cause that affects approximately 5% of pregnant women. The visual system may be affected with variable intensity, being the retinal detachment a rare complication. The retinal detachment in preeclampsia is usually bilateral and serous, and its pathogenesis is related to the choroidal ischemia secondary to an intense arteriolar vasospasm. The majority of patients have complete recovery of vision with clinical management, and surgery is unnecessary. This is a case report of a 27 year old patient who developed the severe form of preeclampsia on her first pregnancy. She had progressive blurred vision, until she could see only shadows. Ophthalmic examination diagnosed spread and bilateral retinal detachment. With blood pressure control at postpartum, the patient had her retina reattached, and recovery of vision.

Exercise testing in hypertensive patients taking different angiotensin-converting enzyme inhibitors

OBJECTIVE: To compare blood pressure response to dynamic exercise in hypertensive patients taking trandolapril or captopril. METHODS: We carried out a prospective, randomized, blinded study with 40 patients with primary hypertension and no other associated disease. The patients were divided into 2 groups (n=20), paired by age, sex, race, and body mass index, and underwent 2 symptom-limited exercise tests on a treadmill before and after 30 days of treatment with captopril (75 to 150 mg/day) or trandolapril (2 to 4 mg/day). RESULTS: The groups were similar prior to treatment (p<0.05), and both drugs reduced blood pressure at rest (p<0.001). During treatment, trandolapril caused a greater increase in functional capacity (+31%) than captopril (+17%; p=0.01) did, and provided better blood pressure control during exercise, observed as a reduction in the variation of systolic blood pressure/MET (trandolapril: 10.7±1.9 mmHg/U vs 7.4±1.2 mmHg/U, p=0.02; captopril: 9.1±1.4 mmHg/U vs 11.4±2.5 mmHg/U, p=0.35), a reduction in peak diastolic blood pressure (trandolapril: 116.8±3.1 mmHg vs 108.1±2.5 mmHg, p=0.003; captopril: 118.2±3.1 mmHg vs 115.8±3.3 mmHg, p=0.35), and a reduction in the interruption of the tests due to excessive elevation in blood pressure (trandolapril: 50% vs 15%, p=0.009; captopril: 50% vs 45%, p=0.32). CONCLUSION: Monotherapy with trandolapril is more effective than that with captopril to control blood pressure during exercise in hypertensive patients.

Influence of pore size distribution on drying behaviour of porous media by a continuous model

Bundle of capillaries, drying kinetics, continuous model, relative permeability, capillary pressure, control volume method

Electronic compliance monitoring in resistant hypertension: the basis for rational therapeutic decisions.

OBJECTIVE: Incomplete compliance is one of several possible causes of uncontrolled hypertension. Yet, non-compliance remains largely unrecognized and is falsely interpreted as treatment resistance, because it is difficult to confirm or exclude objectively. The goal of this study was to evaluate the potential benefits of electronic monitoring of drug compliance in the management of patients with resistant hypertension. METHODS: Forty-one hypertensive patients resistant to a three-drug regimen (average blood pressure 156/ 106 +/- 23/11 mmHg, mean +/- SD) were studied prospectively. They were informed that for the next 2 months, their presently prescribed drugs would be provided in electronic monitors, without any change in treatment, so as to provide the treating physician with a measure of their compliance. Thereafter, patients were offered the possibility of prolonging the monitoring of compliance for another 2 month period, during which treatment was adapted if necessary. RESULTS: Monitoring of compliance alone was associated with a significant improvement of blood pressure at 2 months (145/97 +/- 20/15 mmHg, P < 0.01). During monitoring, blood pressure was normalized (systolic < 140 mmHg or diastolic < 90 mmHg) in one-third of the patients and insufficient compliance was unmasked in another 20%. When analysed according to tertiles of compliance, patients with the lowest compliance exhibited significantly higher achieved diastolic blood pressures (P = 0.04). In 30 patients, compliance was monitored up to 4 months and drug therapy was adapted whenever necessary. In these patients, a further significant decrease in blood pressure was obtained (from 150/100 +/- 18/15 to 143/94 +/- 22/11 mmHg, P = 0.04/0.02). CONCLUSIONS: These results suggest that objective monitoring of compliance using electronic devices may be a useful step in the management of patients with refractory hypertension, as it enables physicians to take rational decisions based on reliable and objective data of drug compliance and hence to improve blood pressure control.