bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance of Ultrawideband Wireless Tags for On-Body Radio Channel Characterisation
Authors: Khan Mohammad Monirujjaman , Abbasi Qammer H. , Alomainy Akram , Hao Yang
Published: August 2012

Experimental characterisation of on-body radio channel for ultrawideband (UWB) wireless active tags is reported in this paper. The aim of this study is to investigate the performance of the commercially available wireless tags on the UWB on-body radio channel characterisation. Measurement campaigns are performed in the chamber and in an indoor environment. Statistical path loss parameters of nine different on-body radio channels for static and dynamic cases are shown and analyzed. Results demonstrated that lognormal distribution provides the best fits for on-body propagation channels path loss model. The path loss was modeled as a function of distance for 34 different receiver locations for propagation along the front part of the body. A reduction of 11.46% path loss exponent is noticed in case of indoor environment as compared to anechoic chamber. In addition, path loss exponent is also extracted for different body parts (trunk, arms, and legs). Second-order channel parameters as fade probability (FP), level crossing rate (LCR), and average fade duration (AFD) are also investigated.
Total Energy of Charged Black Holes in Einstein-Maxwell-Dilaton-Axion Theory
Authors: Korunur Murat , Açıkgöz Irfan
Published: August 2012

We focus on the energy content (including matter and fields) of the Møller energy-momentum complex in the framework of Einstein-Maxwell-Dilaton-Axion (EMDA) theory using teleparallel gravity. We perform the required calculations for some specific charged black hole models, and we find that total energy distributions associated with asymptotically flat black holes are proportional to the gravitational mass. On the other hand, we see that the energy of the asymptotically nonflat black holes diverge in a limiting case.
Hematological Malignancies Escape from NK Cell Innate Immune Surveillance: Mechanisms and Therapeutic Implications
Authors: Farnault Laure , Sanchez Carole , Baier Céline , Le Treut Thérèse , Costello Régis T.
Published: August 2012

Hematological malignancies treatment improved over the last years resulting in increased achievement of complete or partial remission, but unfortunately high relapse rates are still observed. Therefore, sustainment of long-term remission is crucial. Immune system has a key role in tumor surveillance. Natural killer (NK) cells, at the frontier of innate and adaptive immune system, have a central role in tumor cells surveillance as demonstrated in the setting of allogenic stem cell transplantation. Nevertheless, tumor cells develop various mechanisms to escape from NK cells innate immune pressure. Abnormal NK cytolytic functions have been described in nearly all hematological malignancies. We present here various mechanisms involved in the escape of hematological malignancies from NK cells surveillance: NK cells quantitative deficiency and NK cell qualitative deficiency by increased inhibition signaling or decreased activating stimuli. A challenge of immunotherapy is to restore an efficient antitumor response. A combination of classical therapy plus immune modulation strategies will soon become a standard of care for hematological malignancies.
Novel Combination of Impella and Extra Corporeal Membrane Oxygenation as a Bridge to Full Recovery in Fulminant Myocarditis
Authors: Narain Sachin , Paparcuri Gian , Fuhrman Thomas M. , Silverman Richard B. , Peruzzi William T.
Published: July 2012

A 31-year-old male was transferred to our hospital with severe heart failure due to viral myocarditis. He progressed to multiorgan failure requiring intubation and maximal doses of multiple vasopressors. Circulatory support was provided with an Impella device as a bridge to an extracorporeal membrane oxygenation (ECMO) system. On full mechanical cardiovascular support, the patient's hemodynamic status improved and ECMO and Impella were explanted after 48 hours. Three days later, he was extubated and continued on to a full recovery. There are no specific therapies for fulminant myocarditis but first-line treatment is supportive care. ECMO is commonly used in patients with severe heart failure. In severe systolic dysfunction, left ventricular decompression is required to reduce myocardial wall stress, decrease myocardial oxygen requirements, and enhance the chances of recovery. The Impella, an active support system, is less invasive than classical decompressive techniques and is associated with lower requirements for blood products with fewer thromboembolic complications. This is the only case reported of the contemporary use of Impella and ECMO as a bridge to full recovery in an adult with myocarditis. It also presents a novel use of the Impella device in decompressing the left ventricle of an adult patient on ECMO.
A General Latent Class Model for Performance Evaluation of Diagnostic Tests in the Absence of a Gold Standard: An Application to Chagas Disease
Authors: Pereira Gilberto de Araujo , Louzada Francisco , Barbosa Valdirene de Fátima , Ferreira-Silva Márcia Maria , Moraes-Souza Helio
Published: July 2012

We propose a new general Bayesian latent class model for evaluation of the performance of multiple diagnostic tests in situations in which no gold standard test exists based on a computationally intensive approach. The modeling represents an interesting and suitable alternative to models with complex structures that involve the general case of several conditionally independent diagnostic tests, covariates, and strata with different disease prevalences. The technique of stratifying the population according to different disease prevalence rates does not add further marked complexity to the modeling, but it makes the model more flexible and interpretable. To illustrate the general model proposed, we evaluate the performance of six diagnostic screening tests for Chagas disease considering some epidemiological variables. Serology at the time of donation (negative, positive, inconclusive) was considered as a factor of stratification in the model. The general model with stratification of the population performed better in comparison with its concurrents without stratification. The group formed by the testing laboratory Biomanguinhos FIOCRUZ-kit (c-ELISA and rec-ELISA) is the best option in the confirmation process by presenting false-negative rate of 0.0002% from the serial scheme. We are 100% sure that the donor is healthy when these two tests have negative results and he is chagasic when they have positive results.
Pharmacodynamic Interaction ofQuercus infectoriaGalls Extract in Combination with Vancomycin against MRSA Using Microdilution Checkerboard and Time-Kill Assay
Authors: Basri Dayang Fredalina , Khairon Radhiah
Published: July 2012

The galls ofQuercus infectoriaOlivier possess astringent properties which helps in the tightening of the vaginal epithelium in the post-natal period. The present study aimed to observe the time-kill kinetics of the acetone and methanol extracts of gall ofQ. infectoriain combination with vancomycin against two methicillin-resistantStaphylococcus aureus(MRSA) strains; ATCC 33591 and MU 9495 (laboratory-passaged strain). Minimum inhibitory concentration (MIC) of the extracts were determined using microdilution technique whereas the checkerboard and time-kill kinetics were employed to verify the synergistic effects of treatment with vancomycin. The FIC index value of the combinations against both MRSA strains showed that the interaction was synergistic (FIC index<0.5). Time-kill assays showed the bactericidal effect of the combination treatment at 1/8XMIC of the extract and 1/8XMIC of vancomycin, were respectively at7.2±0.28 hr against ATCC 33591 compared to complete attenuation of the growth of the same strain after 8 hr of treatment with vancomycin alone. In conclusion, the combination extracts ofQ. infectoriawith vancomycin were synergistic according to FIC index values. The time-kill curves showed that the interaction was additive with a more rapid killing rate but, which did not differ significantly with vancomycin.
The Interspinous Spacer: A Clinicoanatomical Investigation Using Plastination
Authors: Kaulhausen Thomas , Zarghooni Kourosh , Stein Gregor , Knifka Jutta , Eysel Peer , Koebke Juergen , Sobottke Rolf
Published: August 2012

Purpose. The relatively new and less-invasive therapeutic alternative “interspinous process decompression device (IPD)” is expected to result in improved symptoms of neurogenic intermittent claudication (NIC) caused by lumbar spinal stenosis. The aim of the study was to analyze IPD position particularly regarding damage originating from surgical implantation.Methods. Anatomic assessments were performed on a fresh human cadaver. For the anatomic examination, the lumbar spine was plastinated after implantation of the IPDs. After radiographic control, serial 4 mm thick sections of the block plastinate were cut in the sagittal (L1–L3) and horizontal (L3–L5) planes. The macroanatomical positioning of the implants was then analyzed. The insertion procedure caused only little injury to osteoligamentous or muscular structures. The supraspinous ligament was completely intact, and the interspinous ligaments were not torn as was initially presupposed. No osseous changes at the spinal processes were apparent. Contact of the IPD with the spinous processes was visible, so that sufficient biomechanical limitation of the spinal extension seems likely.Conclusions. Minimally invasive IPD implantation with accurate positioning in the anterior portion of the interspinous place is possible without severe surgical trauma.
Impact of Diabetes and Hyperglycemia on Survival in Advanced Breast Cancer Patients
Authors: Villarreal-Garza Cynthia , Shaw-Dulin Robin , Lara-Medina Fernando , Bacon Ludwing , Rivera Daniel , Urzua Lorena , Aguila Christian , Ramirez-Morales Rebeca , Santamaria Julieta , Bargallo Enrique , Mohar Alejandro , Herrera Luis A.
Published: July 2012

Purpose. We examined the impact of diabetes and hyperglycemia on cancer-specific survival of patients with metastatic or recurrent breast cancer (BC).Methods. We performed a retrospective analysis of 265 patients with advanced BC receiving palliative chemotherapy. BC-specific mortality was compared for diabetic and nondiabetic patients as well as for patients that presented hyperglycemia during treatment.Results. No difference was observed between the diabetic and nondiabetic patients in terms of overall survival (OS). A difference in OS was observed between nondiabetic patients and diabetic patients who had hyperglycemia. The OS was greater in diabetic patients with proper metabolic control than diabetic patients with hyperglycemia. The risk of death was higher in patients with mean glucose levels 130 mg/dL during treatment. Several factors were associated with poor OS: tumor stage, hormone-receptor-negative tumors, HER2 negative disease, multiple metastatic sites, presence of visceral metastases, and mean glucose 130 mg/dL.Conclusion. Elevated glucose levels are associated with a poor outcome in diabetic and nondiabetic patients in contrast to patients with normoglycemic levels, conferring an elevated risk of death. According to these results, clinicians should monitor glucose levels during treatment for advanced breast cancer disease and take action to maintain normal glucose levels.
Role of Intra- and Peritumoral Budding in the Interdisciplinary Management of Rectal Cancer Patients
Authors: Zlobec Inti , Borner Markus , Lugli Alessandro , Inderbitzin Daniel
Published: July 2012

The presence of tumor budding (TuB) at the invasive front of rectal cancers is a valuable indicator of tumor aggressiveness. Tumor buds, typically identified as single cells or small tumor cell clusters detached from the main tumor body, are characterized by loss of cell adhesion, increased migratory, and invasion potential and have been referred to as malignant stem cells. The adverse clinical outcome of patients with a high-grade TuB phenotype has consistently been demonstrated. TuB is a category IIB prognostic factor; it has yet to be investigated in the prospective setting. The value of TuB in oncological and pathological practice goes beyond its use as a simple histomorphological marker of tumor aggressiveness. In this paper, we outline three situations in which the assessment of TuB may have direct implications on treatment within the multidisciplinary management of patients with rectal cancer: (a) patients with TNM stage II (i.e., T3/T4, N0) disease potentially benefitting from adjuvant therapy, (b) patients with early submucosally invasive (T1, sm1-sm3) carcinomas at a high risk of nodal positivity and (c) the role of intratumoral budding assessed in preoperative biopsies as a marker for lymph node and distant metastasis thus potentially aiding the identification of patients suitable for neoadjuvant therapy.
Obesity and Appetite Control
Authors: Suzuki Keisuke , Jayasena Channa N. , Bloom Stephen R.
Published: August 2012

Obesity is one of the major challenges to human health worldwide; however, there are currently no effective pharmacological interventions for obesity. Recent studies have improved our understanding of energy homeostasis by identifying sophisticated neurohumoral networks which convey signals between the brain and gut in order to control food intake. The hypothalamus is a key region which possesses reciprocal connections between the higher cortical centres such as reward-related limbic pathways, and the brainstem. Furthermore, the hypothalamus integrates a number of peripheral signals which modulate food intake and energy expenditure. Gut hormones, such as peptide YY, pancreatic polypeptide, glucagon-like peptide-1, oxyntomodulin, and ghrelin, are modulated by acute food ingestion. In contrast, adiposity signals such as leptin and insulin are implicated in both short- and long-term energy homeostasis. In this paper, we focus on the role of gut hormones and their related neuronal networks (the gut-brain axis) in appetite control, and their potentials as novel therapies for obesity.
Bandwidth Behavior of Closely Spaced Aperture-Coupled Reflectarrays
Authors: Venneri F. , Costanzo S. , Di Massa G.
Published: July 2012

The bandwidth features of reflectarray antennas are analyzed by examining in detail the phase errors due to the compensation mechanism for spatial phase delays. A bandwidth estimation rule is defined, taking into account the combined effects due to the overall antenna geometry and the frequency response of the single reflectarray element. An aperture-coupled reflectarray configuration with reduced interelement spacing is considered as broadband solution for the implementation of small reflectarrays. A 20 GHz aperture-coupled element is synthesized for the design of a 12 diameter reflectarray, showing a simulated 1 dB gain bandwidth of 23%.
Ultrasonic Flaw Imaging via Multipath Exploitation
Authors: Zhang Yimin D. , Shen Xizhong , Demirli Ramazan , Amin Moeness G.
Published: August 2012

We consider ultrasonic imaging for the visualization of flaws in a material. Ultrasonic imaging is a powerful nondestructive testing (NDT) tool which assesses material conditions via the detection, localization, and classification of flaws inside a structure. We utilize reflections of ultrasonic signals which occur when encountering different media and interior boundaries. These reflections can be cast as direct paths to the target corresponding to the virtual sensors appearing on the top and bottom side of the target. Some of these virtual sensors constitute a virtual aperture, whereas in others, the aperture changes with the transmitter position. Exploitations of multipath extended virtual array apertures provide enhanced imaging capability beyond the limitation of traditional multisensor approaches. The waveforms observed at the physical as well as the virtual sensors yield additional measurements corresponding to different aspect angles, thus allowing proper multiview imaging of flaws. We derive the wideband point spread functions for dominant multipaths and show that fusion of physical and virtual sensor data improves the flaw perimeter detection and localization performance. The effectiveness of the proposed multipath exploitation approach is demonstrated using real data.
Plasmonic Modes of Metamaterial-Based Slot Waveguides
Authors: Rukhlenko Ivan D. , Premaratne Malin , Agrawal Govind P.
Published: August 2012

Most metamaterials exhibit pronounced anisotropic properties that are crucial for the understanding of their superior optical behavior, especially when they are integrated into the structure of a plasmonic waveguide. In this paper, we analytically solve the dispersion relation for a slot plasmonic waveguide filled with an anisotropic-stratified metamaterial and reveal that it supports two modes featuring relatively long propagation lengths in the limit of vanishing slot thickness. We classify these modes according to their physical origin and study the variation of their dispersion properties with material parameters.
An Integrated Gateway for Various PHDs in U-Healthcare Environments
Authors: Park KeeHyun , Pak JuGeon
Published: July 2012

We propose an integrated gateway for various personal health devices (PHDs). This gateway receives measurements from various PHDs and conveys them to a remote monitoring server (MS). It provides two kinds of transmission modes: immediate transmission and integrated transmission. The former mode operates if a measurement exceeds a predetermined threshold or in the case of an emergency. In the latter mode, the gateway retains the measurements instead of forwarding them. When the reporting time comes, the gateway extracts all the stored measurements, integrates them into one message, and transmits the integrated message to the MS. Through this mechanism, the transmission overhead can be reduced. On the basis of the proposed gateway, we construct a u-healthcare system comprising an activity monitor, a medication dispenser, and a pulse oximeter. The evaluation results show that the size of separate messages from various PHDs is reduced through the integration process, and the process does not require much time; the integration time is negligible.
Free-Boundary Seepage from Asymmetric Soil Channels
Authors: Carabineanu Adrian
Published: July 2012

We present an inverse method for the study of the seepage from soil channels without lining. We give integral representations of the complex potential, velocity field, stream lines, free phreatic lines, and contour of the channel by means of Levi-Civitá's functionω. For different values of the Taylor coefficients ofω, we calculate numerically the contour of the channel, the phreatic lines, the seepage loss, the velocity field, the stream lines, and the equipotential lines. Examples are given for various symmetric or asymmetric channels, with smooth contours or with angular points.
Entomopathogens Isolated from Invasive Ants and Tests of Their Pathogenicity
Authors: Zarzuela Maria Fernanda Miori de , Leite Luis Garrigós , Marcondes José Eduardo , Campos Ana Eugênia de Carvalho
Published: July 2012

Some ant species cause severe ecological and health impact in urban areas. Many attempts have been tested to control such species, although they do not always succeed. Biological control is an alternative to chemical control and has gained great prominence in research, and fungi and nematodes are among the successful organisms controlling insects. This study aimed to clarify some questions regarding the biological control of ants. Invasive ant species in Brazil had their nests evaluated for the presence of entomopathogens. Isolated entomopathogens were later applied in colonies ofMonomorium floricolaunder laboratory conditions to evaluate their effectiveness and the behavior of the ant colonies after treatment. The entomopathogenic nematodesHeterorhabditissp. andSteinernemasp. and the fungiBeauveria bassiana,Metarhizium anisopliae, andPaecilomycessp. were isolated from the invasive ant nests.M. floricolacolonies treated withSteinernemasp. andHeterorhabditissp. showed a higher mortality of workers than control. The fungusBeauveria bassianacaused higher mortality ofM. floricolaworkers. However, no colony reduction or elimination was observed in any treatment. The defensive behaviors of ants, such as grooming behavior and colony budding, must be considered when using fungi and nematodes for biological control of ants.
Translation Regulation as a Therapeutic Target in Cancer
Authors: Grzmil Michal , Hemmings Brian A.
Published: August 2012

Protein synthesis is a vital cellular process that regulates growth and metabolism. It is controlled via signaling networks in response to environmental changes, including the presence of nutrients, mitogens, or starvation. The phosphorylation state of proteins involved in translation initiation is a limiting factor that regulates the formation or activity of translational complexes. In cancer cells, hyperactivated signaling pathways influence translation, allowing uncontrolled growth and survival. In addition, several components of translation initiation have been found to be mutated, posttranslationally modified, or differentially expressed, and some act as oncogenes in cancer cells. Translational alterations can increase the overall rate of protein synthesis as well as activate regulatory mechanisms leading to the translation of specific messenger RNAs for proteins that promote cancer progression and survival. Many recent studies investigating such mechanisms have produced ideas for therapeutic intervention. This review describes altered mechanisms of protein synthesis in human cancers and discusses therapeutic approaches based on the targeting of translation. Cancer Res; 72(16); 3891–900. ©2012 AACR.
Stroke Mimics Treated with Thrombolysis: Further Evidence on Safety and Distinctive Clinical Features
Authors: Guillan Marta , Alonso-Canovas Araceli , Gonzalez-Valcarcel Jaime , Garcia Barragan Nuria , Garcia Caldentey Juan , Hernandez-Medrano Ignacio , DeFelipe-Mimbrera Alicia , Sanchez-Gonzalez Victor , Terecoasa Elena , Alonso de Leciñana Maria , Masjuan Jaime
Published: July 2012

Background: Patients who present with symptoms mimicking ischaemic stroke (IS), but have a different diagnosis, are known as stroke mimics (SM). The necessity for rapid administration of intravenous thrombolysis in patients with acute IS may lead to treatment of patients with conditions mimicking stroke. A variable proportion of patients with SM (1.4–14%) are currently treated with intravenous tissue plasminogen activator therapy (IV-tPA). The outcome of these patients is generally favourable and complications are rather infrequent. We aimed to determine the frequency, clinical features and prognosis of SM patients treated with IV-tPA in an experienced stroke centre. Methods: A prospective registry was assembled with patients treated with IV-tPA at our stroke unit from January 2004 to December 2011. We recorded age, gender, baseline National Institutes of Health Stroke Scale (NIHSS) score, treatment delay, vascular risk factors, clinical syndrome and aetiology. We retrospectively analysed the clinical characteristics of SM, safety (symptomatic intracranial haemorrhage and mortality) and outcome measures (modified Rankin Scale at 3 months, mRS) and compared them with IS patients. Results: 621 patients were treated with IV-tPA during the study period, 606 (97.5%) were IS and 15 (2.4%) were SM. The aetiology of SM was somatoform disorders (5), headache and neurological deficits with cerebrospinal fluid lymphocytosis (HaNDL) syndrome (3), herpetic encephalitis (2), glial tumours (2), and migraine with aura, focal seizure and cortical vein thrombosis in single cases. SM were younger (72 ± 14 vs. 53.7 ± 16 years, p < 0.05), had a lower baseline deficit [NIHSS 13 (9–18) vs. 8 (5–10), p < 0.05], fewer vascular risk factors, and left hemisphere symptoms were predominant (80 vs. 52.4%, p < 0.05). Global aphasia without hemiparesis (GAWH) was the presenting symptom in 8 (54%) SM and 44 (7%) IS (p < 0.05). Multimodal computed tomography was performed in 3 SM patients and showed perfusion deficits in 2 of them. No intracranial haemorrhage or disability (functional outcome at 3 months, mRS >2) was recorded in any SM patient. Conclusions: The use of intravenous thrombolysis appears to be safe in our SM patients, and prognosis is universally favourable. Somatoform disorder and HaNDL syndrome were prominent causes, and GAWH the most common presentation. The safety of thrombolysis in SM suggests that delaying or withholding treatment may be inappropriate: the benefit of thrombolysis in case of IS may outweigh the risks of treating an SM. Further studies may assess the future role of multimodal computed tomography in the differential diagnosis between IS and SM.
Cost-effectiveness of antihypertensive treatment. General considerations.
Authors: Russell L B
Published: August 2012

Cost-effectiveness analysis, a set of methods for estimating the costs and health effects of medical interventions, helps decision makers to compare alternative treatments and to decide which interventions are appropriate in which situations. This article outlines some fundamental principles of cost-effectiveness analysis and discusses the characteristics necessary if alternative therapies are to be more cost-effective than traditional drug treatment for hypertension. The discussion focuses primarily on the newer drugs like angiotensin converting enzyme inhibitors, alpha-adrenergic receptor blockers, and calcium antagonists.
Hypertension as a risk factor for renal disease. Review of clinical and epidemiological evidence.
Authors: Whelton P K , Klag M J
Published: August 2012

Renal failure is a well-recognized complication of accelerated and malignant hypertension that can be prevented by appropriate antihypertensive therapy. The risk of renal disease in patients with milder forms of hypertension is less certain. Death certificate, insurance industry, and community-based observational studies provide little information with respect to the risk of kidney damage in the hypertensive patient. Randomized controlled trials of antihypertensive drug therapy provide equivocal results. The strongest evidence in support of the hypothesis that mild hypertension increases the risk of subsequent renal disease comes from analyses of the Hypertension Detection and Follow-up Program and the Medicare End-Stage Renal Disease (ESRD) Program. The risk of blood pressure-related ESRD appears to be especially high in blacks, independent of age, sex, and prevalence of hypertension. Although these results need to be confirmed, the data raise the possibility that the effects of high blood pressure on the kidney are different in blacks than in whites. Based on current trends, it is projected that the number of beneficiaries in the Medicare ESRD Program will continue to increase during the next 30-40 years and that the diagnosis of hypertensive ESRD will become increasingly common. Additional studies to characterize the relation between mild hypertension and subsequent risk of renal disease and to confirm the corresponding benefits of antihypertensive therapy are urgently needed.
Nonpharmacological therapy of hypertension. Commentary on diet and blood pressure.
Authors: Langford H G
Published: August 2012

The use of dietary measures as sole therapy for hypertension has generated much enthusiasm and is supported by epidemiological and anecdotal data but is not substantiated by long-term controlled trials. Dietary measures should be effective in preventing the rise in blood pressure with age in civilized populations, but there are no firm data to substantiate this hypothesis. However, some data do suggest that weight loss and sodium restriction may benefit the drug-treated hypertensive patient. There are strong reasons to consider the use of nonpharmacological measures for the treatment of mild hypertension. Mild hypertension is ubiquitous. Some population subsets have a prevalence of mild hypertension approaching 40%, based on one blood pressure determination, for individuals older than 50 years. Even if the true prevalence is closer to 15%, this is a high proportion of the population in need of drug therapy. If a change in lifestyle could reduce the need for drug therapy by a respectable percentage, then an enormous number of individuals could be spared the necessity of taking antihypertensive medication.
Stimulation of renin release by intrarenal calcium infusion.
Authors: Lahera V , Fiksen-Olsen M J , Romero J C
Published: August 2012

The effects of intrarenal infusions of calcium gluconate (10 and 100 micrograms Ca/kg/min) on renin secretion were studied in anesthetized mongrel dogs. In one group, the two doses of calcium were infused for 30 minutes each (1 ml/min). In a second group, the same doses were administered 30 minutes after the start of infusion of prostaglandin synthesis inhibitors (indomethacin 10 micrograms/kg/min intrarenal or injection of meclofenamate 5 mg/kg i.v. bolus). Mean arterial pressure, renal blood flow, and glomerular filtration rate remained unchanged during the infusion of calcium in both groups. The infusion of 10 micrograms Ca/kg/min increased renin secretion 77% and sodium excretion 123%. During the infusion of 100 micrograms Ca/kg/min, renin secretion was not different from precalcium values, whereas urinary 6-keto-PGF1 alpha, urine flow, sodium, potassium, and calcium excretion rates were increased (p less than 0.05). During the administration of prostaglandin synthesis inhibitors, the urinary 6-keto-PGF1 alpha levels were reduced, and the infusion of 10 micrograms Ca/kg/min failed to increase renin secretion, sodium excretion, or 6-keto-PGF1 alpha excretion rates. The infusion of 100 micrograms Ca/kg/min during prostaglandin synthesis inhibition did not modify urine flow or sodium excretion; however, potassium and calcium excretions increased. It is concluded that 1) the intrarenal infusion of small doses of calcium gluconate is capable of stimulating renin secretion through a prostaglandin-mediated mechanism, and 2) the stimulation of renin secretion as well as the increase in sodium excretion induced by calcium are independent of hemodynamic alterations.
Magnitude, reproducibility, and components of the pressor response to the clinic.
Authors: Elijovich F , Laffer C L
Published: August 2012

We investigated the magnitude of the pressor response to the clinic with ambulatory monitors by comparing blood pressure readings related to the medical visit with all clinic-unrelated readings during the day. One hundred studies were conducted on 51 hypertensive patients who were placed either on placebo (67) or on monotherapy with hydrochlorothiazide, atenolol, or the converting enzyme inhibitors captopril or zofenopril. On placebo, clinic-related systolic (162 +/- 2), diastolic (101 +/- 1), and pulse (61 +/- 2) pressures (mm Hg) were significantly higher than the respective clinic-unrelated values (149 +/- 2, 93 +/- 1, and 56 +/- 1 mm Hg). Heart rates were not different. Despite significant reductions of blood pressure, the same pattern was found during treatment. After initiating the monitoring and while in transit to job or home (initial component of the clinic-related readings), systolic (166 +/- 2 mm Hg) and pulse (64 +/- 2 mm Hg) pressures were higher than those during return to the office the next day (final component, 158 +/- 3 and 58 +/- 2 mm Hg). Blood pressures of both components, however, were significantly higher than the clinic-unrelated ones. In 19 repeat studies carried out 2-24 months apart on placebo, the average pressor response did not change from the first (13 +/- 3/11 +/- 2) to the second (13 +/- 4/11 +/- 2 mm Hg) procedure. No correlation, however, was found between the first and second study responses of individual patients.(ABSTRACT TRUNCATED AT 250 WORDS)
Antihypertensive drugs distinctly modulate the rapid resetting of the baroreceptors.
Authors: de Abreu G R , Salgado H C
Published: August 2012

We investigated the distinct ability of various antihypertensive drugs to modulate the extent (%) of rapid (15 minutes) resetting of the baroreceptors of normotensive rats to hypotensive levels. In one protocol, hemorrhage produced a complete resetting to hypotension in rats chronically treated (6 days) with captopril. Also, hemorrhage produced only partial resetting in rats acutely treated (10-15 minutes before baroreceptor recording) with captopril and in control (untreated) rats (73 +/- 7% and 49 +/- 5%, respectively). In another protocol, all vasodilators produced hypotension in normotensive rats. Nifedipine produced complete (93 +/- 4%) resetting to hypotension, whereas prazosin produced near-maximal (83 +/- 3%) resetting. The remaining drugs studied (phenoxybenzamine, trimethaphan, and MgSO4) induced a partial resetting (63 +/- 7%, 63 +/- 9%, and 50 +/- 5%, respectively) that did not differ significantly from the extent observed with hemorrhage in control (untreated) rats. These results demonstrate that different antihypertensive drugs distinctly modulate rapid baroreceptor resetting to hypotensive levels and that nifedipine and long-term treatment with captopril associated with hemorrhage modulate rapid resetting to hypotension in a more efficient manner.
Reciprocal effects of dexamethasone on vasodilatory responses to arachidonic acid and prostanoids in the isolated perfused rabbit kidney.
Authors: Sessa W C , Lin L , Nasjletti A
Published: August 2012

We reported that dexamethasone treatment of rabbits causes a reduction in renal vasoconstrictor responses to prostaglandin F2 alpha and U46619, an agonist at the thromboxane-endoperoxide receptor, but not to phenylephrine. The purpose of this study was to examine if dexamethasone treatment can affect the renal vasodilatory responses to prostacyclin (PGI2) and prostaglandin E2 (PGE2) in isolated Krebs-perfused kidneys constricted with phenylephrine. In kidneys from dexamethasone-treated rabbits, the vasodilatory response to PGI2 was reduced by 57%, whereas that to PGE2 was converted to a vasoconstrictor response. This effect of dexamethasone appears to be specific in that the renal vasodilatory responses to forskolin and to sodium nitroprusside were not affected by the steroid. Contrasting with the inhibitory effect of dexamethasone on prostanoid-induced renal vasodilation, treatment with dexamethasone augmented the renal vasodilatory response to arachidonic acid; for example, arachidonic acid, at 10 micrograms decreased perfusion pressure by 24.8 +/- 5.4 and 49.0 +/- 5.6 mm Hg in kidneys from vehicle- and dexamethasone-treated rabbits, respectively. The enhanced vasodilatory effect of arachidonic acid could not be attributed to increased renal formation of PGE2 and PGI2. In conclusion, dexamethasone interferes with prostanoid-mediated renal vasodilation, which is not associated with an impairment in renal responsiveness to direct activators of adenylate cyclase and guanylate cyclase. The reciprocal effect of dexamethasone on the renal vascular responses to arachidonic acid and vasodilatory prostanoids are indicative of a previously unrecognized influence of glucocorticoids on the renal arachidonate-prostaglandin system.
Interactions among calcium, sodium, and alcohol intake as determinants of blood pressure.
Authors: Hamet P , Mongeau E , Lambert J , Bellavance F , Daignault-Gélinas M , Ledoux M , Whissell-Cambiotti L
Published: August 2012

It has been reported that calcium intake may effectively modulate the expression of hypertension affected by sodium. The present study extends our previous analysis of this calcium-sodium interaction, additionally demonstrating that calcium, sodium, and alcohol intake further contribute to both systolic and diastolic blood pressures in normotensive subjects. Calcium intake was related to lower blood pressure over all ranges of sodium and alcohol intake, and alcohol intake contributed positively and significantly to both systolic and diastolic blood pressures. However, sodium was associated with increased blood pressure only at low calcium intake, particularly in subjects who consumed large amounts of alcohol. This study points to a significant interaction among sodium, calcium, and alcohol intake as determinants of blood pressure, which, together with gender and weight, contribute to 31% of systolic blood pressure and with the addition of age to 36% of the variance in diastolic blood pressure.
Dietary sodium reduction for hypertension prevention and treatment.
Authors: Elmer P J , Grimm R H , Flack J , Laing B
Published: August 2012

Nutritional-nonpharmacological approaches for the treatment and prevention of hypertension are of great interest. Sodium reduction is one of the primary methods recommended for these purposes. The general public is interested in the reduction of dietary sodium intake and has responded with a decrease in table salt use, the purchase of lowered sodium food products, and the use of food labels to help guide food purchases. Countervailing trends in the use of convenience foods and dining out increase the difficulty for individuals to lower sodium intake. Clinical trials that have used sodium reduction alone or in combination with other lifestyle therapies have demonstrated the feasibility of reducing dietary sodium intake from 30% to 50% for up to 4 years, in a variety of populations. Trials that used lifestyle and weight loss interventions have also achieved significant reductions in body weight and alcohol consumption and increases in physical activity. A variety of studies indicate that long-term sodium reduction is feasible and that it is acceptable to patients. No negative consequences of these interventions have been observed, and in some cases improvement in the intake of other nutrients has occurred. Nonpharmacological interventions have resulted in hypertension control in significant proportions of the trial populations. These studies demonstrate that the foregoing types of interventions can significantly contribute to hypertension treatment and prevention.
Experimental hypertension.
Authors: Bohr D F , Dominiczak A F
Published: August 2012

Several interventions are used to induce hypertension in the experimental animal. The three most used interventions are renal ischemia, mineralocorticoid excess, and genetic manipulation. The sequence of events leading from these initiating manipulations to the elevated arterial pressure is being explored to define the mechanism responsible for hypertension. The following mechanisms are currently extensively evaluated: Pressor and depressor factors of renal origin, neurogenic regulation, circulating humoral factors, vessel wall hypertrophy, and membrane transport abnormality. The experimental models of hypertension hold great promise in providing an understanding of the mechanisms and developing effective treatment in clinical hypertension.
Salt sensitivity. Definition, conception, methodology, and long-term issues.
Authors: Sullivan J M
Published: August 2012

Several laboratories have examined the relation between salt intake and blood pressure in both experimental animals and humans. The human studies have used widely varying methodologies and different criteria for sodium sensitivity. Nonetheless, these studies have produced convincing data that the blood pressure of some individuals is far more sensitive to the effects of sodium depletion or loading than that of others. Furthermore, a minority of the population appears to comprise acutely salt-sensitive individuals. Some studies have shown that sodium-sensitive individuals share several characteristics. They include increased forearm vascular resistance, decreased venous compliance, suppressed plasma renin activity, and lower circulating aldosterone concentration. These findings have also been described in the Dahl salt-sensitive rat, which suggest a genetic link in humans as well as the rat. Long-term follow-up of sodium-sensitive and sodium-resistant groups has shown that although blood pressure levels are approximately equal in the two groups during sodium depletion, resumption of a daily sodium intake of about 150 meq results in significantly higher levels of blood pressure and forearm vascular resistance in the sodium-sensitive group. This difference persists for at least 12 months.
Independence of pressure reactivity from pressure levels in Tecumseh, Michigan.
Authors: Julius S , Jones K , Schork N , Johnson E , Krause L , Nazzaro P , Zemva A
Published: August 2012

The relation between blood pressure level and reactivity to mental arithmetic and isometric exercise was investigated in 169 men and 120 women (average age, 32.3 years) from the village of Tecumseh, Mich. In the entire population, the correlation between baseline blood pressure and blood pressure response to both stressors was not significant. Blood pressure reactivity to both stressors was not increased in participants with borderline hypertension (one clinic reading of more than 140 mm Hg systolic and/or 90 mm Hg diastolic). When subjects were classified according to blood pressure response (below and above the 80th percentile), the hyperreactors to mental and physical stress had normal baseline blood pressure values. The hyperreactors also had clinic-to-home blood pressure differences similar to those of the rest of the population. Participants who had borderline hypertension at age 32 years had significantly elevated blood pressures at ages 5, 8, 12, 21, and 22 years. Those who were hyperreactors at age 32 years had normal blood pressures as children and young adults. Results of the present study lend no support to an association between higher blood pressures and blood pressure hyperreactivity. Study participants in Tecumseh will be recalled for future examinations. The independence of blood pressure levels from blood pressure reactivity offers a unique opportunity to prospectively evaluate their separate effects on cardiovascular morbidity.
Stress and sodium intake in neural control of renal function in hypertension.
Authors: DiBona G F
Published: August 2012

The interaction between genetic and environmental factors is important in the pathophysiology of hypertension. By examining the effects of two environmental factors--acute psychoemotional stress and dietary sodium intake--in rats with genetic hypertension, an important influence on central neural mechanisms governing the renal sympathetic neural control of renal function has been demonstrated. Additional studies of the central opioid systems have demonstrated an important role of opioid peptides in modulating the renal functional responses to acute psychoemotional stress. The observed renal functional alterations--antidiuresis, antinatriuresis, and renal vasoconstriction--are known to be capable of contributing to the initiation, development, and maintenance of the hypertensive process.
Are some antihypertensive therapies more efficacious than others in preventing complications and prolonging life?
Authors: Tifft C P , Chobanian A V
Published: August 2012

Antihypertensive therapy has been used for almost 35 years to reduce blood pressure and prevent morbidity and mortality related to the hypertensive state. Malignant, severe, and moderate hypertension have all been shown to be worthy of drug treatment, but controversy remains as to the degree of benefit that is achievable by treating milder hypertension. A variety of clinical trials have demonstrated that antihypertensive therapy reduces the incidence of stroke, congestive heart failure, and left ventricular hypertrophy and the progression in severity of hypertension. The benefits with respect to prevention of coronary heart disease (CHD) have been much less impressive. Thiazide diuretics have been the base therapy for the bulk of the hypertensive subjects studied to date who have not demonstrated reduced incidence of CHD. Therapy with beta-blockers has the potential for reducing CHD, but an analysis of four studies finds only two with positive results. On the other hand, since that study found reduced total mortality as well as CHD compared with thiazide diuretic, its findings cannot be ignored. Other questions deserving further investigation include how other antihypertensive therapies compare with respect to the risk reduction found with thiazide diuretics and beta-blockers, the optimal posttreatment blood pressure, whether persons with mild hypertension benefit from therapy, whether women should be treated differently, and whether atherosclerosis may be affected by specific antihypertensive therapies.
Local hormonal factors (intracrine, autocrine, and paracrine) in hypertension.
Authors: Carretero O A , Scicli A G
Published: August 2012

Vasoactive hormones acting as endocrine, neuroendocrine, or local hormonal systems (intracrine, autocrine, and paracrine) are an important component of the many factors that regulate blood pressure. Hypertension may be the result of an alteration in the balance between vasodepressor and vasopressor hormonal systems. Changes in this balance could be due to genetic factors such as mutations in one of the genes of the vasoactive system or environmental factors that alter the synthesis and release of one or more vasoactive hormones. Endocrine and neuroendocrine vasopressor hormonal systems, such as the renin-angiotensin system and catecholamines, play a well-established and important role in the regulation of blood pressure and the pathogenesis of some secondary forms of hypertension. The blockade of such systems has already resulted in effective antihypertensive treatment. The role of local hormonal systems is less well established; however, recent evidence suggests they also play an important role in the regulation of blood pressure and the pathogenesis of hypertension. Some vasopressor hormonal systems, such as the renin-angiotensin system, can act as both endocrine or local hormonal systems. Work using transgenic rats harboring the mouse Ren-2 gene has conclusively demonstrated that the renin-angiotensin system, acting as a local hormonal system, has the capability to cause severe hypertension. Whether this model of experimental hypertension mimics any type of human hypertension is not known. Vasodepressor hormones such as kinins, prostaglandins, and endothelium-derived relaxing factor (EDRF) act mainly as local hormonal systems, with the notable exception of atrial natriuretic factor, which may act as both an endocrine and a local hormone. The tissue kallikrein-kinin system, acting either directly or via paracrine eicosanoids or EDRF, participates in local regulation of the circulation, renal function, and the acute antihypertensive effect of angiotensin converting enzyme inhibitors. A restriction fragment length polymorphism (RFLP) that distinguishes the kallikrein gene family of a strain of spontaneously hypertensive rats (SHR) from normotensive Brown Norway rats has been identified. In a set of 32 recombinant inbred strains derived from these SHR and Brown Norway strains, the RFLP marking the kallikrein gene family of SHR cosegregated with an increase in blood pressure. Also, in a study of Utah families it was found that a dominant-allele kallikrein gene expressed as high urinary kallikrein excretion was associated with a decreased risk of essential hypertension. In conclusion, vasopressor and vasodepressor hormones, acting not only as endocrine but also as local hormones, play an important role in the regulation of blood pressure and the pathogenesis of hypertension.(ABSTRACT TRUNCATED AT 400 WORDS)